natural killer cells in the orchestration of chronic ...journalofimmunologyresearch 5 nk cells...

Review ArticleNatural Killer Cells in the Orchestration of ChronicInflammatory Diseases

Luca Parisi1 Barbara Bassani2 Marco Tremolati1 Elisabetta Gini3

Giampietro Farronato1 and Antonino Bruno2

1Department of Biomedical Surgical and Dental Sciences University of Milan Milan Italy2Scientific and Technological Pole IRCCS MultiMedica Milan Italy3Department of Biotechnology and Life Sciences (DBSV) University of Insubria Varese Italy

Correspondence should be addressed to Luca Parisi lucaparisiunimiit

Received 4 October 2016 Revised 4 January 2017 Accepted 18 January 2017 Published 27 March 2017

Academic Editor Margarete D Bagatini

Copyright copy 2017 Luca Parisi et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Inflammation altered immune cell phenotype and functions are key features shared by diverse chronic diseases includingcardiovascular neurodegenerative diseases diabetes metabolic syndrome and cancer Natural killer cells are innate lymphoidcells primarily involved in the immune system response to non-self -components but their plasticity is largely influenced by thepathological microenvironment Altered NK phenotype and function have been reported in several pathological conditionsbasically related to impaired or enhanced toxicity Here we reviewed and discussed the role of NKs in selected different andldquodistantrdquo chronic diseases cancer diabetes periodontitis and atherosclerosis placing NK cells as crucial orchestrator of thesepathologic conditions

1 Introduction

Inflammation is now considered a crucial hallmark of chronicdisorders including cardiovascular [1] neurodegenerativediseases [2ndash4] diabetes [5 6] metabolic syndrome [7 8]and cancer [9ndash11] Inflammation acts as a relevant orches-trator in their insurgence development and progression[1 2 6 10] Inflammatory cells which comprise cells frominnate ad adaptive immunity are characterized by differentphenotype and functions which involve direct (by con-tact) or distant (by soluble factors) interaction with theirtarget cells [12ndash14] Immune cells form either innate oradaptive immunity given their cellular plasticity have beenreported to acquire an altered phenotype upon differentstimuli This has been described for diverse immune celltype including macrophages (M) neutrophils (N) myeloid-derive-suppressor cells (MDSC) dendritic cells (DC) naturalkiller (NK) cells and T cells [12ndash14] Immune cell alteredfunctions include attenuation of targetingkilling activitiestolerogenicimmunosuppressive behaviour and the acquisi-tion of proangiogenic functions These alterations occurring

at both tissue levels and systemically are finely tuned bythe (chronic) pathological environment Here we focused onNKs as key orchestrator in inflammatory chronic diseasessuch cancer type 1 diabetes periodontitis and atherosclero-sis The aim was to discuss how such very different patholo-gies with diverse aetiology and photogenic mechanismsshare a common and relevant hallmark such inflammationdissecting whether NK cells act as crucial orchestrators in theinduction and progression of the conditions selected

NKs are innate lymphoid cells primarily involved inthe host defence against infection and in the process oftumour immunosurveillance A part from their crucial rolein those processes NK cells are involved in the graft-versus-host disease the regulation of haematopoiesis and exertregulatory effects on the adaptive immune cell counterpart[15] Virus infected and tumour transforming cells sharethe feature of lownull expression of the MHC-I moleculerepresenting one of the mechanisms through which NK cellsare able to recognize targetnon-self -cells Nevertheless thismechanism alone does not trigger cytotoxicity unless it iscombined with the altered expression of other molecules

HindawiJournal of Immunology ResearchVolume 2017 Article ID 4218254 13 pageshttpsdoiorg10115520174218254

2 Journal of Immunology Research

CD56CD16

Cytokines

KIRs

Perforin

Granzymes

NKG2D

CD56dimCD16+

(a)

CD56CD16 NKG2A

TNFs

IFNs

IL‐10

NKG2D

CD56brightCD16minus

(b)

CD56

VEGF

KIRs

NKG2D

CD9

CD49a

PLGFSDF‐1IL‐8

CD56superbrightCD16minus

(c)

Figure 1 Different human NK subsets Three different NK subsets have been characterized on the basis of distinctive surface antigenexpression and described as (a) CD56dimCD16+ that represents the conventional cytotoxic NKs characterized by the high release of perforinand granzymes (b) CD56brightCD16minus that are able to release a large amount of cytokines (c) CD56superbrightCD16minus that are able to produceproangiogenic factors including VEGF IL-8 and SDF-1 and are characterized by the expression of specific surface markers as CD9 andCD49a

on the target cell surface acting as activatory ligands NKcells are equipped with surface receptors that trigger cellactivation (immunoreceptor tyrosine-based activationmotifs(ITAM)) or inhibition (immune tyrosine-based inhibitorymotifs (ITIM)) [16] NK cells also directly contribute toadaptive immune responses interacting with DCs and bytriggering T cell responses Induction of DC maturation toproduce TNF-120572 and IL-12 and upregulation of costimulatoryligands are triggered by NK cells [17] Moreover NK cellsproliferate and acquire cytotoxic activity and the capacityto produce IFN-120574 through the interaction with DCs [18]Apart from activation of other cells of innate immunityNK cells also enhance induction of CD8+ T cell responsesthat is influenced by NK-released IFN-120574 which promotesantigen processing and presentation to T cells and T helpertype 1 (Th1) cell polarization [19] Two major circulatinghuman NK cell subsets have been characterized based onthe expression of surface antigens CD56 an isoform of thehuman neural cell adhesion molecule and CD16 the low-affinity Fc receptor necessary for the antibody-dependentcellular cytotoxicity (ADCC) Peripheral NK cells are pre-dominantly CD56dimCD16+ cytotoxic NK cells acting mainlythrough the release of perforin a membrane pore-formingtoxin and granzyme which activates the apoptotic cascadeon target cells However approximately 5 of circulatingNK cells show a CD56brightCD16minus phenotype These cellscan produce high levels of some cytokines Upon activationCD56brightCD16minus NK cells release IFN-120574 and TNF-120572 andthey kill target cells more efficiently [20]Within the develop-ing decidua a third NK subset is found the decidual NK cell(dNK) dNK cells display a CD56superbrightCD16minus phenotype[21] and are closely linked with vascularization of the deciduain both humans and mice dNK cells physiologically produceVEGF PlGF and IL-8 are poorly cytotoxic and are associatedwith the induction of CD4+ T regulatory (Treg) cells [22 23](Figure 1)

2 Natural Killer Cells and Cancer

Strong evidences suggest that the presence of inflammatorycells within the tumour microenvironment (TME) plays acrucial role in the development andor progression of humancancers [10 12 24ndash27] Among the host-dependent biologicalfeatures of the tumour hallmarks defined by Hanahan andWeinberg [28] there are ldquoevading immune destructionrdquo andldquotumour-promoting inflammationrdquo which together with theimmune orchestration of angiogenesis point out the key roleof the immune system in neoplastic diseases [9 10 12 24]

Alterations in NK cell activity have been describedin different type of cancer and are associated with theinduction of a tolerogenic and lesspoor cytotoxic func-tions with decreased expression of the activatory receptorNKG2D altered degranulation and release of perforin andgranzyme Recently Bruno et al identified a new NK cellsubset in tissue and peripheral blood of non-small-celllung cancer (NSCLC) patients termed respectively tumourinfiltrating (TINKs) and tumour associated (TANKs) NKswhich are able to promote angiogenesis [29 30] NSCLCTINKTANKs are characterized by a decidual like pheno-type CD56brightCD16minusVEGFhighPlGFhighIL-8+IFN-120574low ableto promote endothelial cell migration and induction ofcapillary-like structures [29 30]

Several TME released components including TGF-120573hypoxia and adenosine mostly shared with the decidualtissues are implicated in NK cell response against tumours[31] (Figure 2)

TGF-120573 is one of the numerous TME factors involvedin the induction of immune cell polarization [32] and isexpressed at high levels both in the tumour microenvi-ronment and in the decidua [29] During carcinogenesisTGF-120573 acts as a tumour suppressor by inhibiting tumourcell replication and favouring apoptosis [33 34] while atlater stages of tumour progression it exerts protumourigenic

Journal of Immunology Research 3

CD56

CD16

Cytokines

KIRs

Perforin

Granzymes

NKG2D

Adenosine

Hypoxia

H+

H+H+

H+H+

H+

Acidity

TGF‐120573

TEXOs

CD56

VEGF

KIRs

NKG2D

CD9

CD49a

PLGFSDF‐1IL‐8

O2

O2

O2

O2

Figure 2 Soluble factors within the tumour microenvironment shaping NK cell functions Several molecules and soluble factors within thetumourmicroenvironment including TGF-120573 hypoxia adenosine acidic of the environment and tumour exosomes (TEXOs) can inhibit NKresponse against tumours either by interfering with NK cell directcytokinemediated tumour cell lysis or by supporting tumour angiogenesis

effects that include tumour survival induction of epithelial-mesenchymal transition (EMT) enhanced tumour invasionand immunosuppressive and proangiogenic activities [32ndash34] TGF-120573 has been found to polarize the CD56dimCD16+peripheral NK cells towards a decidual like phenotypedefined asCD56brightCD16minus andKIR+ CD9+ CD49a+ [29 35ndash37] TGF-120573 has been shown to inhibit CD16mediated humanNK cell IFN-120574 production and ADCC though SMAD3[36] Bruno et al demonstrated that TGF-120573 significantlycontributes in the induction of the angiogenic-switch of NK

cells from healthy individuals [30] promoting the inductionof the TINKTANK CD56brightCD16minusVEGFhighPlGFhighIL-8+INF120574low phenotype in vitro

A hypoxic microenvironment is another common featureshared between the decidua and the TME [38 39] Acombination of TGF-120573 hypoxia and 5-aza-21015840-deoxycytidinea demethylating agent has been found to convert FACSsorted peripheral blood CD56dimCD16+NK cells into dNKscharacterized by low cytotoxicity and high expression levelsof VEGF the CD9 dNK marker and KIRs [36]


Adenosine is a soluble immunomodulatory moleculeacting through adenosine receptors expressed on diverseimmune cell type including NK cells [40 41] Up to 20-fold increases in the adenosine content in extracellular fluidof solid carcinomas have been reported [42] Adenosineaccumulation is partially associated with hypoxia and itsrelease in the extracellular environment and can impairNK cell cytolytic activities by decreasing TNF-120572 secretion(following IL-2 stimulation) decreasing cytotoxic granuleexocytosis and attenuating perforin and Fas ligand-mediatedcytotoxic activity as far as cytokine release Most of theseeffects are attributed to stimulation of the cyclic adenosinemonophosphateprotein kinase A (PKA) pathway followingthe binding of adenosine to A2A receptors on NK cells[43]

Recently great interests arise on tumour released vesiclesincluding exosomes in shaping immune cell response [4445] Exosomes are small (40 to 110 nm) membrane vesiclesof endocytic origin which are actively secreted from severalcell types Exosome content includes a variety of biologicallyactive molecules such as proteins mRNAs and miRNAsreflecting the cell of origin They probably mediate a rangeof local and systematic functions including immune stim-ulation or suppression cell-to-cell communication deliv-ery of proteins and genetic material including miRNAtumour immune escape and tumour cell communication[46 47] Tumour derived exosomes appear to regulate NKcells impairing their killing activity by downregulating per-foringranzyme production andor NKG2D ligand expres-sion [48 49] Exosome release could explain the effects oftumours on the polarization of peripheral NK cells towardsTANK phenotype The NKG2DNKG2DL system plays animportant role in tumour immune surveillance [42 48 49]There are convincing evidences that exosomes derived fromdiverse cancer cell lines including mesothelioma breast andprostate cancer cells express NKG2D ligands and therebydownregulate NKG2D expression on NK cells and CD8+ Tcells resulting in impaired cytotoxic effector functions [48ndash50] It has also been shown that leukaemialymphoma T andB cells secrete NKG2D ligand-expressing exosomes with theability to impair the cytotoxic potency of NK and T cells fromhealthy donors [44 45]

Recently STAT5 has been proposed as a key regulatorin NK cells and demonstrated that STAT5 acts as a molec-ular switch from tumour surveillance to tumour promotion[39] Consistent with its function as the major STAT pro-tein downstream of IL-7 IL-2 and IL-15 Gotthardt et alreported STAT5 role in tumour angiogenesis showing thatStat5ΔΔNcr1-iCreTg-Vav-Bcl2 mice displayed an increasedtumour growth compared with wild-type mice [51] In addi-tion production of VEGF by NK cells is higher in STAT5-deficient mice compared with wt-mice To elucidate the roleof VEGF production in NKp46+ cells Gotthardt and col-leagues established VegfaΔΔNcr1-iCreTg mice characterizedby NKp46+VEGFminus cells In v-abl+ tumour RMA-S and A-MuLV-induced leukaemia tumour models they showed asignificant reduction of tumour burden and fewer CD31+blood vessels in tumours

3 Natural Killer Cells in Type 1 Diabetes

Type 1 diabetes (T1D) an autoimmune disease characterizedby almost complete beta cell destruction and hyperglycaemiaaccounts for only about 5ndash10 of all cases of diabeteswhereas its incidence is dramatically increasing worldwideover the last 50 years [52] Different immune cells suchmacrophages and dendritic and T cells have been suggestedto play crucial roles in type 1 diabetes pathogenesis [53ndash55]The contribution of autoreactive T cells to the destruction ofpancreatic 120573 cells as a consequence of an immunologicallymediated destruction of the pancreatic tissues has beenproposed as the key pathogenicmechanisms in type 1 diabetes[56 57] Nevertheless diverse inflammatory cells from bothinnate and adaptive immunity interact with the pancreaticparenchyma supporting the overall inflammatory state inT1D NKs cells represent the major source of IFN-120574 aTh1 proinflammatory cytokine acting as a master regulatorof different immune cell response High release of IFN-120574within the pancreatic tissues inT1Dpatientsmay significantlycontribute to the excessive uncontrolled and unresolvedautoimmune response mediated by autoreactive T cellsWhile NK cell response against autologous pancreatic islethas been reported in vitro [58] contrasting results have beenreported in in vivo models

Two in vivo studies correlate NK cells to diabetes pro-gression In the first study (Figure 3(a)) an in vivo model ofcoxsackievirus B4- (CVB4-) induced diabetes was employedshowing that NK antiviral defence raised by beta cells inresponse to IFNs resulted in a reduced permissiveness toinfection and subsequent natural killer (NK) cell-dependentdeath [59] Another in vivo study (Figure 3(b)) using a T cellreceptor transgenic model where T1D was induced via anti-CTLA-4 mAb treatment revealed that higher frequency ofNK cells exited in aggressive insulitis resulting in b-islet celldestruction [60]

Conversely there are several reports supporting a pro-tective role exerted by NK cells in NOD mice undergoingcomplete Freundrsquos adjuvant (CFA) In this work NODSCIDmice immunizedwith CFA recover its protective effects whenCD3minusDX5+ NKs were adoptively transferred into animalrecipients by downregulating autoreactive T cell response[61] (Figure 3(c))

Whether the murine model employed is relevant for theNK cell behaviour detected in the context of T1D is stilldebated For example NOD mice are characterized by anunusual genetic composition in the genomic regions thatinfluence NK cell activity

The NKG2D activatory receptor has been demonstratedto be overexpressed inNODNKs due to the overexpression ofits Rae-1 ligand Further diverse NK cell inhibitory receptorshave been found to be differentially expressed in NOD miceas compared to C57BL6 control animals [62] Altogetherthese genetic peculiarities may explain the low NKs activitydetected in NODmice [62 63]

Moving to humans (Figure 3(d)) contrasting results havebeen reported as well (Figure 2) Most of them documentedlow number of circulating NK cells in T1D patients [64ndash66] or a functional altered state [67 68] The major concern


NK cells120573‐Pancreatic

cells

Lysis

CVB4

Low NKnumberactivity

(a)

120572-CTLA 4

High NK number

Insulitis

NK cells

Lysis

(b)

NKs

Autoreactive CTL

NODSCID CFA

Inhibition

NK cells

CD3minusDX5+

T cells

(c)

Lower expression of the NCR NKp30 and NKp40KIR2DS3 gene

(d)

Figure 3 Natural killer cells in type1 diabetes Several in vivo studies correlate NK cells to diabetes progression an in vivo model ofcoxsackievirus B4- (CVB4-) induced diabetes showed that NK antiviral defence resulted in a reduced permissiveness to infection andsubsequentNK cell-dependent death (a) Anti-CTLA-4mAb treatment of T cell receptor transgenicmice demonstrated that higher frequencyof NK cells induces aggressive insulitis resulting in b-islet cell destruction (b) A protective role of NK cells was reported in NOD miceundergoing complete Freundrsquos adjuvant (CFA) NODSCID mice immunized with CFA recover its protective effects when CD3minusDX5+ NKsare adoptively transferred into animal recipients by downregulating autoreactive T cell response (c) In human samples lower expressionof the NKp30 and NKp40 was detected in type 1 diabetic patients as compared with control Type 1 diabetic patients display an increasedfrequency of KIR gene haplotypes including the activating KIR2DS3 gene with a genetic interaction between the KIR and HLA complexes(d)

regarding these studies is that even if NK cells were directlyisolated from T1D patients the detection of functionalalteration was performed by assessing NK cell cytolysis onK562 tumour cells

Rodacki et al investigated the frequency and activatorystate of peripheral blood NK cells in individuals with T1Dat different stages (recent versus long-standing onset) [6970] No significant difference between the activatory stateas detected by IFN-120574 and perforin release was observedbetweenNK cells derived from either recent or long-standingT1D patients In contrast lower expression of the NCRNKp30 and NKp40 was detected in NK cell isolated fromlong-standing type 1 as compared with control subjectsFurther gene expression analysis revealed that type 1 dia-betic patients display an increased frequency of KIR genehaplotypes including the activating KIR2DS3 gene with agenetic interaction between the KIR and HLA complexes[69 70]

4 Natural Killer Cells in Periodontitis

Periodontitis defined as the inflammation of the periodon-tium involving the supporting tissues of the teeth affects asmuch as 80 of the middle-aged population by comparisonthe prevalence of aggressive periodontitis reaches up to1ndash15 [71]

The role of NK cells in periodontitis has been poorlyinvestigated however decreasedTh cells and upregulation ofNK cells during CP have been documented [72]

The role of NKs in periodontitis represents a still debatedissue Indeed contrasting results have been reported by usinghuman specimensWhile someof them showed a relationshipbetween NK number phenotype and periodontal state [73ndash76] others reported no significant correlation [73 77]

Relevant increase of CD57 NK cells has been observed byFujita et al and related to periodontal diseases progressionas a consequence of an unresolved immune response withinperiodontal tissues [73ndash76]


P gingivalis

A Actinomycetemcomitans

NKp46

PGE2PGE2MMPs

TNF‐120572 FibroblastsMacrophages

NKs

Osteoblast

Osteoclast

Dendritic cells

IL‐12

NKs

CRACC

Dendritic cells

Cytokines type 1IFN‐120574

F nucleatum

A actinomycetemcomitans

F nucleatum

PGE2

AB E

C

D

osteoprotegerin

Figure 4 Interaction between NK cells and the main bacterial species involved in the pathogenesis of periodontitis Direct recognition ofFusobacterium nucleatum through NKp46 worsts periodontal disease (A) Actinobacillus actinomycetemcomitans stimulate dendritic cellsthat in turn elicit rapid gamma interferon responses by natural killer cells (B) P gingivalis induces a rapidly increase of type 1 cytokineproduction by both dendritic cells and NK cells (C) Aggregatibacter actinomycetemcomitans induces CD2-like receptor activating cytotoxiccells (CRACC) on NK cells via activation of dendritic cells and subsequent interleukin 12 (IL-12) signalling that results in an aggressive (D)NK cell following F nucleatum recognition can release TNF-120572 that on one hand leads to tissue damage by stimulating prostaglandin E2 releasefrommonocytes and fibroblasts and secretion of metalloproteinases that degrade extracellular matrix (ECM) proteins and on the other handinduces osteoclast differentiation and activation by increasing RANKL expression and the suppression of osteoprotegerin a cytokine receptorthat belongs to tumour necrosis factor (TNF) receptor superfamily expression in osteoblasts resulting in alveolar bone resorption (E)

Contrast studies conducted by Fujita et al and Cobb etal revealed relatively low numbers of natural killer cells inchronic gingivitis and periodontitis samples as compared tohealthy subjectsrsquo correlation [73 77]

Conversely in vitro studies have focused on the inter-action between NK cells and the main bacterial speciesinvolved in the pathogenesis of periodontitis (Figure 4) likeA actinomycetemcomitans P gingivalis and F nucleatum[78]

Direct recognition of Fusobacterium nucleatum a gram-negative anaerobe microorganism ubiquitous to the oralcavity [79] by the NK cell natural cytotoxicity receptorNKp46 has been reported to aggravate periodontal disease[78] (Figure 4(A))

Actinobacillus actinomycetemcomitans a gram-negativebacterium which has been associated with severe oral infec-tions [80] has been shown to elicit rapid gamma interferonresponses by natural killer cells via dendritic cell stimulation[81] (Figure 4(B)) Increased type 1 cytokine production byboth dendritic cells and NK cells following exposition to Pgingivalis has been described resulting in increased P gin-givalis-specific IgG2 [81] (Figure 4(C)) Aggregatibacter acti-nomycetemcomitans a gram-negative anaerobic bacteriumstrongly associated with localized aggressive periodontitis

[82] has been reported to indirectly induces CD2-like recep-tor activating cytotoxic cells (CRACC) on NK cells viaactivation of dendritic cells and subsequent IL-12 signalling[83] CRACC induction was reported to be more signifi-cantly pronounced in aggressive than chronic periodontitisand positively correlated with periodontal disease severitysubgingival levels of specific periodontal pathogens and NKcell activation in vivo [83] (Figure 4(D))

Other relevant mechanisms driving NK cell contributionto periodontitis involve ncr1 receptor recognition of stillunknown ligands on F nucleatum surface This interactionresulted in TNF-120572 secretion that on one hand leads totissue damage by stimulating prostaglandin E2 release frommonocytes and fibroblasts secretion of metalloproteinasesthat degrade extracellular matrix (ECM) proteins and on theother hand induces osteoclast differentiation and activationby increasing RANKL expression and the suppression ofosteoprotegerin a cytokine receptor that belongs to tumournecrosis factor (TNF) receptor superfamily expression inosteoblasts resulting in alveolar bone resorption [78] (Fig-ure 4(E))

Several conditions associated with periodontitis havebeen related to alteration inNK cells cytotoxicity A part from


those related to bacterial infections T2DM [67] smokinghabits [84] have been included as related conditions

Fanconi anemia (FA) an autosomal recessive disordercharacterized by progressive pancytopenia and congenitalmalformation of the skeleton [85] periodontitis and gingivi-tis represents common inflammatory states in patients withFA [85] Natural killer (NK) cell numbers and function havebeen reported to be decreased in some FA patients and thiswas associated with impairment in the differentiation processof the NK cells subsets [85 86] Myers et al showed perforinand granzyme reduced content inNKcells fromchildrenwithFA as compared to controls [87]

Zeidel et al reported that smokers without chronicobstructive pulmonary disease (COPD) showed impairedNK cytotoxic activity in peripheral blood and alteration insystemic production of pro- and anti-inflammatory cytokines[84]

A study performed on Papillon-Lefevre syndrome (PLS)an autosomal recessive disorder that exited in aggressiveperiodontitis [88] revealed NK cell anergy as comparedto healthy subjects with impairment of NK cell cytotoxicfunction [89]

5 Natural Killer Cells in Atherosclerosis

Atherosclerosis is a chronic inflammatory disease affectingelastic and large muscular arteries that are characterized bylesions containing cholesterol immune cells smooth musclecells and necrotic cores Macrophages dendritic cells andT cells represent the major immune cells populations withindeveloping lesions even if other immune cell componentsare involved including NK cells [90] Indeed NKs have beenobservedwithin atherosclerotic plaques in humans as far as inmice [91 92] and it has been demonstrated that in advancedatherosclerotic lesions they mostly localized in the necroticcore adjacent tissues deep within plaques and in shoulderregions [90]

It has been suggested that several cytokines and chemok-ines within lesions may be directly involved in NK cellrecruitment towards atherosclerotic plaque Among allmonocyte chemoattractant protein-1 (MCP-1) [93] as well asfractalkine (CX3CL1) has been shown as relevant cytokinesable to enhance NK cell migration and activation result-ing in an increased IFN-120574 release [94] In addition IL-15 IL-12 IL-18 and IFN-120572 which represent major NK cellchemoattractants have been shown to promote atherogenicprocess potentially activating NK cells or promoting theircrosstalk with other immune cells including DC and mono-cytesmacrophages [95ndash97] (Figure 5(a)) NKs have beenshown to participate in atherosclerosis via activatory recep-tors that recognizeMHC-Imolecules (MICAandMICB) [98]and by releasing IFN-120574 a proinflammatory cytokine [99] Inthis context it was demonstrated that oxidized low-densitylipoprotein (LDL) can promote NKdendritic cell crosstalkby activating the CD48-2B4 axis and inducing an increasedproduction of IFN-120574 by NKs [100] (Figure 5(a))

To specifically confirm that NK cells infiltrate the vesselwall and contribute to atherosclerotic promotion and lesiondevelopment several in vivo models have been employed

Whitman et al create a chimeric atherosclerosis-susceptibleLDL receptor null (ldl-rminusminus) mouse model also character-ized by the impairment of NK cell functionality throughthe expression of a transgene encoding for Ly49A Theydemonstrated that even if no difference in either serumtotal cholesterol concentrations or lipoprotein cholesteroldistribution was observed between the two groups of micein Ly49A transgenic group the deficiency of functional NKcells significantly reduced the size of atherosclerosis by 70in cross-sectional analysis of the aortic root and by 38 in theintimal surface of the aortic arch [92 99] (Figure 5(b))

Selathurai et al demonstrated that treatments with anti-Asialo-GM1 inApoE(minusminus)mice resulted inNKcells depletionwithout affecting other lymphocytes ratios associated withreduced atherosclerosis (Figure 5(c))These effects have beenshown to be independent from plasma lipids MoreoverNKs isolated from mouse spleens for adoptive transfer intolymphocyte-deficient ApoE(minusminus)Rag2(minusminus)IL2rg(minusminus) miceconfirmed the proatherogenic activity of NK cells Furtherthe transfer of IFN-120574-deficient NK cells but not granzymeB and perforin-deficient NK cells resulted in an increasedlesion size in the lymphocyte-deficient ApoE(minusminus) mice as inwild-type NK cells Necrotic core was increased by wild-typeNK cells whereas no changes were observed with perforin-and granzyme B-deficient NK cell transfer [98] (Figure 5(d))

Cheng et al showed that combined B T and NKcell deficiency accelerates atherosclerosis in BALBc micedemonstrating the impact of lymphocytes includingNKs onlipoprotein metabolism along with the relevant contributionof lymphocyte subsets in plaque composition in atheroscle-rosis [101]

Recent studies have suggested that not only might thepresence of NKs be considered in atherosclerosis progres-sion but also more importantly their ability to influenceother immune cells should be evaluated Several evidencesdemonstrated that NKs within atherosclerotic plaque areactivated by dendritic cells NK-released cytokines are able inturn to promote DC maturation leading to an exacerbationinflammatory responseNKDC crosstalkmight be envisagedas a potential interaction occurring within atheroscleroticlesions which might worsen disease progression [102] (Fig-ure 5(a)) In fact the crosstalk between activated dendriticcellsmacrophages and NK cells induces IFN-120574 release byNK cells that in turn promotes metalloproteinases (MMPs)secretion from cDCs and MΦ Activated MΦ produce TNF-120572 increasing enhance endothelial cell adhesion moleculesand MMPs can damage the extracellular matrix leading toatherosclerotic plaque destabilization [102] (Figure 5(a))

Indirect evidence that NK cells might contribute toatherosclerotic disease is also provided by clinical obser-vations in atherosclerotic patients Recently in a cohort of124 patients it has been demonstrated that increased NKnumbers were observed in the arm of the study includingthose patients with complications suggesting NK cell directcontribution in atherosclerosis progression [103] Similarly inelderly atherosclerotic patients an increased number of totalcirculating NKs characterized by an impaired cytotoxicitywere shown [104] According to these evidences a significant


IL‐12CD56CD16

KIRs

PerforinGranzymes

NKG2DDendritic cells

Smooth muscle cells

NK cells

Necroticlipidic core

Debris

Cholesterol

Chemoattractants (MCP‐1 CX3CL1 IL‐15 IL‐12 IL‐18 and IFN‐120572)

CD56CD16

KIRsNKG2D

NK cells

OxidizedLDL MMPs Matrix

MΦ

IFN‐120574

IFN‐120574

IFN‐120574

IFN‐120574

(a)

Impairment ofNK functionality

ldl-rminusminusLy49A (Tg) Atherosclerosis

reduction

(b)

120572-Asialo‐GM1

NK depletion

Atherosclerosisattenuation

NK

ApoE(minusminus) mice

cells

(c)

Spleen

ApoE(minusminus)Rag2(minusminus)IL2rg(minusminus) mice Wilde‐type mice

NKcells

NK transfer

Increasedatherosclerosis

(d)

Figure 5 Proatherosclerosis role of natural killer cells NK ability to induce atherosclerosis has been reported in several murinemodels and inhumans Several cytokines and chemokines within atherosclerotic lesions are supposed to promote NK recruitment towards atheroscleroticplaque including monocyte chemoattractant protein-1 (MCP-1) fractalkine (CX3CL1) IL-15 IL-12 IL-18 and IFN-120572 that on one handenhance NK cell migration and on the other hand induce NK activation resulting in an increased IFN-120574 release Moreover these cytokines asfar as oxidized LDL also promote the NK crosstalk with other immune cells that is dendritic cells and macrophages DCs activated NKs byreleasing IL-12 that in turn induce the production of IFN-120574 by NKs that are able to lyse smooth muscle cells In addition IFN-120574 released NKcells that in turn promotemetalloproteinases (MMPs) secretion from cDCs andMΦ (a) In a chimeric atherosclerosis-susceptible low-densitylipoprotein (LDL) receptor null (ldl-rminusminus) mouse model characterized by the impairment of NK cell functionality through the expressionof a transgene encoding for Ly49A it has been demonstrated that even if no difference in either serum total cholesterol concentrations orlipoprotein cholesterol distribution was observed between the two groups of mice in Ly49A transgenic group the deficiency of functionalNK cells significantly reduced the size of atherosclerosis by 70 in cross-sectional analysis of the aortic root and by 38 in the intimalsurface of the aortic arch (b) The administration of anti-Asialo-GM1 antibodies in ApoE(minusminus) mice induces a NK cells depletion leading toan attenuation of atherosclerosis (c) The transfer of NK cells isolated from murine spleen into ApoE(minusminus)Rag2(minusminus)IL2rg(minusminus) induces anenhancement of atherosclerosis (d)


reduction of CD56dim NK cells and a concomitant loss of NKcell function in terms of cytolytic activity were also found inpatients with unstable coronary artery disease (CAD) [105]

6 Conclusion

The contribution of natural killer cells to inflammatorydisease insurgence and progression represent an intriguingtopic for both basic scientists and clinicians It is nowclear that immune cell plasticity within the pathologicalmicroenvironment acts not only at local tissue but also atsystemic levels Several studies performed in different anddistant pathologies like cancer diabetes and dental disordersthat share an inflammatory state as a crucial hallmark showedaltered NK cell activity at both local and systemic levels Thiswill be crucial to propose NK cells as potential circulatingbiomarkers to early detect diverse syndrome andor predictfurther outcome

Some studies here discussed supported the evidence thataltered NK cell activities (enhanceduncontrolled cytolysisversus impaired cytolytic functions) are associated withprotective or deleterious effects This knowledge suggeststhat further studies requiring proper animal models andtranslation into human are necessary to clarify the contribu-tion of NK cells to the progression of inflammatory-relatedpathologies aiming at identifying potential modulators ableto shape NK cells according to the pathological contextFinally considering their direct and indirect (crosstalk withother arms on innate and adaptive immunity) contribution toinflammatory conditions NK cells can be placed as relevantorchestrators in chronic diseases

Abbreviations

ADCC Antibody-dependent cellular cytotoxicityA-MuLV Abelson murine leukaemia virusCD Cluster of differentiationCFA Complete Freundrsquos adjuvantCOPD Chronic obstructive pulmonary diseaseCP Chronic periodontitisCRACC CD2-like receptor activating cytotoxic

cellsCTLA Cytotoxic T-lymphocyte antigenCVB4 Coxsackievirus B4CX3CL1 FractalkineDC Dendritic cellsdNK Decidual NK cellECM Extracellular matrixFA Fanconi anemiaFACS Fluorescence-activated cell sortingHLA Human leukocyte antigenIFN InterferonIL InterleukinITAM Immunoreceptor tyrosine-based

activation motifsITIM Immune tyrosine-based inhibitory motifsKIR Killer cell immunoglobulin-like receptorLDL Low-density lipoproteinLy49A Killer cell lectin-like receptor subfamily A

M MacrophagesMΦ Naıve macrophagesMCP-1 Monocyte chemoattractant protein-1MDSC Myeloid-derive-suppressor cellsMHC Major histocompatibility complexMICA MHC class I polypeptide-related sequence

AMICB MHC class I polypeptide-related sequence

BMMPs MetalloproteinasesmiRNA Micro-RNAmRNA Messenger RNAN NeutrophilsNCR Natural cytotoxicity receptorsNK Natural killerNKG Natural killer groupNOD Nonobese diabeticNODSCID Nonobese diabeticsevere combined

immunodeficiencyNSCLC Non-small-cell lung cancerPKA Protein kinase APlGF Placental growth factorPLS Papillon-Lefevre syndromeRae Retinoic acid early inducibleRANKL Receptor activator of nuclear factor-120581B

ligandRMA-S Rejected an MHC class I-deficient tumour

cell lineSMAD Small mother against decapentaplegicSTAT Signal transducers and activators of

transcriptionTh T helperTANKs Tumour associated natural killer cellsTINKs Tumour infiltrating natural killer cellsTGF Transforming growth factorTME Tumour microenvironmentTNF Tumour necrosis factorTreg T regulatoryT1D Type 1 diabetesT2DM Type 2 diabetes mellitusv-abl Abelson murine leukaemia viral oncogene

homolog 1VEGF Vascular endothelial growth factor

Disclosure

Luca Parisi and Barbara Bassani are co-first authors andGiampietro Farronato and Antonino Bruno are co-lastauthors

Conflicts of Interest

The authors declare that they have no conflicts of interest

Authorsrsquo Contributions

Luca Parisi Barbara Bassani Giampietro Farronato andAntonino Bruno share equal contribution


Acknowledgments

Barbara Bassani and Elisabetta Gini are students of thePhD program in Biotechnology Biosciences and SurgicalTechnologies School in Biological and Medical SciencesUniversity of Insubria Antonino Bruno was a FIRC (Fon-dazione Italiana per la Ricerca sul Cancro) fellow and iscurrently a fellow for Fondazione Umberto Veronesi (FUV)

References

[1] P Libby ldquoInflammation and cardiovascular disease mecha-nismsrdquo The American Journal of Clinical Nutrition vol 83 no2 pp 456Sndash460S 2006

[2] S Amor F Puentes D Baker and P Van Der Valk ldquoInflamma-tion in neurodegenerative diseasesrdquo Immunology vol 129 no 2pp 154ndash169 2010

[3] CKGlass K Saijo BWinnerMCMarchetto and FHGageldquoMechanisms underlying inflammation in neurodegenerationrdquoCell vol 140 no 6 pp 918ndash934 2010

[4] T Wyss-Coray and L Mucke ldquoInflammation in neurodegener-ative diseasemdasha double-edged swordrdquoNeuron vol 35 no 3 pp419ndash432 2002

[5] M Y Donath ldquoTargeting inflammation in the treatment of type2 diabetes time to startrdquoNature Reviews Drug Discovery vol 13no 6 pp 465ndash476 2014

[6] N Esser S Legrand-Poels J Piette A J Scheen and N PaquotldquoInflammation as a link between obesity metabolic syndromeand type 2 diabetesrdquoDiabetes Research andClinical Practice vol105 no 2 pp 141ndash150 2014

[7] K Esposito and D Giugliano ldquoThe metabolic syndrome andinflammation association or causationrdquoNutrition Metabolismand Cardiovascular Diseases vol 14 no 5 pp 228ndash232 2004

[8] R Monteiro and I Azevedo ldquoChronic inflammation in obesityand the metabolic syndromerdquo Mediators of Inflammation vol2010 Article ID 289645 10 pages 2010

[9] F R Balkwill and AMantovani ldquoCancer-related inflammationcommon themes and therapeutic opportunitiesrdquo Seminars inCancer Biology vol 22 no 1 pp 33ndash40 2012

[10] L M Coussens and Z Werb ldquoInflammation and cancerrdquoNature vol 420 no 6917 pp 860ndash867 2002

[11] C I Diakos K A Charles D C McMillan and S J ClarkeldquoCancer-related inflammation and treatment effectivenessrdquoTheLancet Oncology vol 15 no 11 pp e493ndashe503 2014

[12] A Bruno A Pagani L Pulze et al ldquoOrchestration of angiogen-esis by immune cellsrdquo Frontiers in Oncology vol 4 article 1312014

[13] A Mantovani M A Cassatella C Costantini and S JaillonldquoNeutrophils in the activation and regulation of innate andadaptive immunityrdquo Nature Reviews Immunology vol 11 no 8pp 519ndash531 2011

[14] A Sica and AMantovani ldquoMacrophage plasticity and polariza-tion In vivo veritasrdquo Journal of Clinical Investigation vol 122no 3 pp 787ndash795 2012

[15] B R Blazar W J Murphy and M Abedi ldquoAdvances ingraft-versus-host disease biology and therapyrdquo Nature ReviewsImmunology vol 12 no 6 pp 443ndash458 2012

[16] L L Lanier ldquoTurning on natural killer cellsrdquo Journal ofExperimental Medicine vol 191 no 8 pp 1259ndash1262 2000

[17] F Gerosa B Baldani-Guerra C Nisii V Marchesini G Carraand G Trinchieri ldquoReciprocal activating interaction between

natural killer cells and dendritic cellsrdquo Journal of ExperimentalMedicine vol 195 no 3 pp 327ndash333 2002

[18] N C Fernandez A Lozier C Flament et al ldquoDendritic cellsdirectly trigger NK cell functions cross-talk relevant in innateanti-tumor immune responses in vivordquo Nature Medicine vol 5no 4 pp 405ndash411 1999

[19] R Mocikat H Braumuller A Gumy et al ldquoNatural killer cellsactivated by MHC class ILow targets prime dendritic cells toinduce protective CD8 T cell responsesrdquo Immunity vol 19 no4 pp 561ndash569 2003

[20] E Vivier E Tomasello M Baratin T Walzer and S UgolinildquoFunctions of natural killer cellsrdquo Nature Immunology vol 9no 5 pp 503ndash510 2008

[21] P Le Bouteiller ldquoHuman decidual NK cells unique and tightlyregulated effector functions in healthy and pathogen-infectedpregnanciesrdquo Frontiers in Immunology vol 4 article 404 2013

[22] S M Blois B F Klapp and G Barrientos ldquoDecidualization andangiogenesis in early pregnancy unravelling the functions ofDC and NK cellsrdquo Journal of Reproductive Immunology vol 88no 2 pp 86ndash92 2011

[23] J Hanna D Goldman-Wohl Y Hamani et al ldquoDecidual NKcells regulate key developmental processes at the human fetal-maternal interfacerdquo Nature Medicine vol 12 no 9 pp 1065ndash1074 2006

[24] F R Balkwill M Capasso and T Hagemann ldquoThe tumormicroenvironment at a glancerdquo Journal of Cell Science vol 125no 23 pp 5591ndash5596 2012

[25] A Bruno A Pagani E Magnani et al ldquoInflammatory angio-genesis and the tumor microenvironment as targets for cancertherapy and preventionrdquo Cancer Treatment and Research vol159 pp 401ndash426 2014

[26] S M Crusz and F R Balkwill ldquoInflammation and canceradvances and new agentsrdquo Nature Reviews Clinical Oncologyvol 12 no 10 pp 584ndash596 2015

[27] D M Noonan A De Lerma Barbaro N Vannini L Mor-tara and A Albini ldquoInflammation inflammatory cells andangiogenesis decisions and indecisionsrdquo Cancer andMetastasisReviews vol 27 no 1 pp 31ndash40 2008

[28] D Hanahan and R AWeinberg ldquoHallmarks of cancer the nextgenerationrdquo Cell vol 144 no 5 pp 646ndash674 2011

[29] A Bruno G Ferlazzo A Albini and D M Noonan ldquoA thinktank of TINKTANKs tumor-infiltratingtumor-associatednatural killer cells in tumor progression and angiogenesisrdquoJournal of the National Cancer Institute vol 106 no 8 articledju200 2014

[30] A Bruno C Focaccetti A Pagani et al ldquoThe proangiogenicphenotype of natural killer cells in patients with non-small celllung cancerrdquo Neoplasia vol 15 no 2 pp 133ndash142 2013

[31] J Baginska E Viry J Paggetti et al ldquoThe critical role ofthe tumor microenvironment in shaping natural killer cell-mediated anti-tumor immunityrdquo Frontiers in Immunology vol4 article 490 2013

[32] R A Flavell S Sanjabi S H Wrzesinski and P Licona-LimonldquoThe polarization of immune cells in the tumour environmentby TGFbetardquo Nature Reviews Immunology vol 10 no 8 pp554ndash567 2010

[33] H Ikushima and K Miyazono ldquoTGFΒ 2 signalling a complexweb in cancer progressionrdquo Nature Reviews Cancer vol 10 no6 pp 415ndash424 2010

[34] L Yang Y Pang andH LMoses ldquoTGF-120573 and immune cells animportant regulatory axis in the tumor microenvironment and


progressionrdquo Trends in Immunology vol 31 no 6 pp 220ndash2272010

[35] D S Allan B Rybalov G Awong et al ldquoTGF-beta affectsdevelopment and differentiation of human natural killer cellsubsetsrdquo European Journal of Immunology vol 40 no 8 pp2289ndash2295 2010

[36] A S Cerdeira A Rajakumar C M Royle et al ldquoConversion ofperipheral blood NK cells to a decidual NK-like phenotype by acocktail of defined factorsrdquo Journal of Immunology vol 190 no8 pp 3939ndash3948 2013

[37] D B Keskin D S J Allan B Rybalov et al ldquoTGF120573 promotesconversion of CD16+ peripheral blood NK cells into CD16- NKcells with similarities to decidual NK cellsrdquo Proceedings of theNational Academy of Sciences of the United States of Americavol 104 no 9 pp 3378ndash3383 2007

[38] K D Beaman M K Jaiswal G K Katara et al ldquoPregnancy isa model for tumors not transplantationrdquo American Journal ofReproductive Immunology vol 76 no 1 pp 3ndash7 2016

[39] S G Holtan D J Creedon P Haluska and S N MarkovicldquoCancer and pregnancy parallels in growth invasion andimmune modulation and implications for cancer therapeuticagentsrdquo Mayo Clinic Proceedings vol 84 no 11 pp 985ndash10002009

[40] D W Hoskin J S Mader S J Furlong D M Conrad andJ Blay ldquoInhibition of T cell and natural killer cell function byadenosine and its contribution to immune evasion by tumorcells (Review)rdquo International Journal of Oncology vol 32 no3 pp 527ndash535 2008

[41] V Kumar and A Sharma ldquoAdenosine an endogenous mod-ulator of innate immune system with therapeutic potentialrdquoEuropean Journal of Pharmacology vol 616 no 1ndash3 pp 7ndash152009

[42] G Berchem M Z Noman M Bosseler et al ldquoHypoxic tumor-derived microvesicles negatively regulate NK cell functionby a mechanism involving TGF-beta and miR23a transferrdquoOncoimmunology vol 5 no 4 Article ID e1062968 2016

[43] L Antonioli C Blandizzi P Pacher and G Hasko ldquoImmunityinflammation and cancer a leading role for adenosinerdquo NatureReviews Cancer vol 13 no 12 pp 842ndash857 2013

[44] DW Greening S K Gopal R Xu R J Simpson andW ChenldquoExosomes and their roles in immune regulation and cancerrdquoSeminars in Cell and Developmental Biology vol 40 pp 72ndash812015

[45] J Webber V Yeung and A Clayton ldquoExtracellular vesicles asmodulators of the cancer microenvironmentrdquo Seminars in Celland Developmental Biology vol 40 pp 27ndash34 2015

[46] K Denzer M J Kleijmeer H F G Heijnen W Stoorvogeland H J Geuze ldquoExosome from internal vesicle of themultivesicular body to intercellular signaling devicerdquo Journal ofCell Science vol 113 no 19 pp 3365ndash3374 2000

[47] H Valadi K Ekstrom A Bossios M Sjostrand J J Leeand J O Lotvall ldquoExosome-mediated transfer of mRNAs andmicroRNAs is a novel mechanism of genetic exchange betweencellsrdquo Nature Cell Biology vol 9 no 6 pp 654ndash659 2007

[48] A Clayton J P Mitchell J Court S Linnane M D Masonand Z Tabi ldquoHuman tumor-derived exosomes down-modulateNKG2D expressionrdquo Journal of Immunology vol 180 no 11 pp7249ndash7258 2008

[49] A Clayton and Z Tabi ldquoExosomes and the MICA-NKG2Dsystem in cancerrdquo Blood Cells Molecules and Diseases vol 34no 3 pp 206ndash213 2005

[50] L Muller M Mitsuhashi P Simms W E Gooding and TL Whiteside ldquoTumor-derived exosomes regulate expressionof immune function-related genes in human T cell subsetsrdquoScientific Reports vol 6 article 20254 2016

[51] DGotthardt EM Putz E Grundschober et al ldquoSTAT5 is a keyregulator in NK cells and acts as a molecular switch from tumorsurveillance to tumor promotionrdquo Cancer Discovery vol 6 no4 pp 414ndash429 2016

[52] J E Phillips J J Couper M A S Penno et al ldquoType 1 diabetesa disease of developmental originsrdquo Pediatric Diabetes 2016

[53] J Huang Y Xiao A Xu and Z Zhou ldquoNeutrophils in type 1diabetesrdquo Journal of Diabetes Investigation vol 7 no 5 pp 652ndash663 2016

[54] N Van Gassen W Staels E Van Overmeire et al ldquoConcisereview macrophages versatile gatekeepers during pancreaticbeta-cell development injury and regenerationrdquo Stem CellsTranslational Medicine vol 4 no 6 pp 555ndash563 2015

[55] D H Wagner ldquoOf the multiple mechanisms leading to type1 diabetes T cell receptor revision may play a prominent role(is type 1 diabetes more than a single disease)rdquo Clinical ampExperimental Immunology vol 185 no 3 pp 271ndash280 2016

[56] G S Eisenbarth ldquoType I diabetes mellitus A chronic autoim-mune diseaserdquoNew England Journal ofMedicine vol 314 no 21pp 1360ndash1368 1986

[57] M A Kelly M L Rayner C H Mijovic and A H BarnettldquoMolecular aspects of type 1 diabetesrdquoMolecular Pathology vol56 no 1 pp 1ndash10 2003

[58] A G Baxter and M J Smyth ldquoThe role of NK cells inautoimmune diseaserdquo Autoimmunity vol 35 no 1 pp 1ndash142002

[59] M Flodstrom A Maday D Balakrishna M M Cleary AYoshimura and N Sarvetnick ldquoTarget cell defense prevents thedevelopment of diabetes after viral infectionrdquoNature Immunol-ogy vol 3 no 4 pp 373ndash382 2002

[60] L Poirot C Benoist and D Mathis ldquoNatural killer cellsdistinguish innocuous and destructive forms of pancreatic isletautoimmunityrdquo Proceedings of the National Academy of Sciencesof the United States of America vol 101 no 21 pp 8102ndash81072004

[61] I Lee H Qin J Trudeau J Dutz and R Tan ldquoRegulationof autoimmune diabetes by complete Freunds adjuvant ismediated by NK cellsrdquo Journal of Immunology vol 172 no 2pp 937ndash942 2004

[62] L D Poulton M J Smyth C G Hawke et al ldquoCytometric andfunctional analyses of NK and NKT cell deficiencies in NODmicerdquo International Immunology vol 13 no 7 pp 887ndash8962001

[63] S E Johansson H Hall J Bjorklund and P Hoglund ldquoBroadlyimpaired NK cell function in non-obese diabetic mice ispartially restored by NK cell activation in vivo and by IL-12IL-18 in vitrordquo International Immunology vol 16 no 1 pp 1ndash112004

[64] M J Hussain L Alviggi B A Millward R D G Leslie D APyke and D Vergani ldquoEvidence that the reduced number ofnatural killer cells in Type 1 (insulin-dependent) diabetes maybe genetically determinedrdquoDiabetologia vol 30 no 12 pp 907ndash911 1987

[65] M P N Nair E W Lewis and S A Schwartz ldquoImmunoreg-ulatory dysfunctions in type I diabetes natural and antibody-dependent cellular cytotoxic activitiesrdquo Journal of ClinicalImmunology vol 6 no 5 pp 363ndash372 1986


[66] K Negishi NWaldeck G Chandy et al ldquoNatural killer cell andislet killer cell activities in Type 1 (insulin-dependent) diabetesrdquoDiabetologia vol 29 no 6 pp 352ndash357 1986

[67] R Lorini A Moretta A Valtorta et al ldquoCytotoxic activityin children with insulin-dependent diabetes mellitusrdquo DiabetesResearch and Clinical Practice vol 23 no 1 pp 37ndash42 1994

[68] R GWilson J Anderson B K Shenton M DWhite R M RTaylor and G Proud ldquoNatural killer cells in insulin dependentdiabetes mellitusrdquo British Medical Journal vol 293 no 6541 p244 1986

[69] M Rodacki A Milech and J E P D Oliveira ldquoNK cells andtype 1 diabetesrdquo Clinical and Developmental Immunology vol13 no 2-4 pp 101ndash107 2006

[70] M Rodacki B Svoren V Butty et al ldquoAltered natural killer cellsin type 1 diabetic patientsrdquo Diabetes vol 56 no 1 pp 177ndash1852007

[71] G Hajishengallis ldquoPeriodontitis from microbial immune sub-version to systemic inflammationrdquo Nature Reviews Immunol-ogy vol 15 no 1 pp 30ndash44 2015

[72] O A Gonzalez M J Novak S Kirakodu et al ldquoComparativeanalysis of gingival tissue antigen presentation pathways inageing and periodontitisrdquo Journal of Clinical Periodontologyvol 41 no 4 pp 327ndash339 2014

[73] S Fujita H Takahashi H Okabe Y Ozaki Y Hara and I KatoldquoDistribution of natural killer cells in periodontal diseases animmunohistochemical studyrdquo Journal of Periodontology vol63 no 8 pp 686ndash689 1992

[74] W Kopp ldquoDensity and localization of lymphocytes withnatural-killer (NK) cell activity in periodontal biopsy spec-imens from patients with severe periodontitisrdquo Journal ofClinical Periodontology vol 15 no 10 pp 595ndash600 1988

[75] S Stelin H Ramakrishan A Talwar K V Arun and T SKumar ldquoImmunohistological analysis of CD1a langerhans cellsand CD57 natural killer cells in healthy and diseased humangingival tissue a comparative studyrdquo Journal of Indian Societyof Periodontology vol 13 no 3 pp 150ndash154 2009

[76] S EWynne L JWalsh G J Seymour andRN Powell ldquoIn situdemonstration of natural killer (NK) cells in human gingivaltissuerdquo Journal of Periodontology vol 57 no 11 pp 699ndash7021986

[77] CM Cobb O Singla P H Feil F CTheisen and R E SchultzldquoComparison of NK-cell (Leu-7+ and Leu-11b+) populations inclinically healthy gingiva chronic gingivitis and chronic adultperiodontitisrdquo Journal of Periodontal Research vol 24 no 1 pp1ndash7 1989

[78] S Chaushu A Wilensky C Gur et al ldquoDirect recognitionof fusobacterium nucleatum by the NK cell natural cytotox-icity receptor NKp46 aggravates periodontal diseaserdquo PLoSPathogens vol 8 no 3 Article ID e1002601 2012

[79] Y W Han R W Redline M Li L Yin G B Hill and TS McCormick ldquoFusobacterium nucleatum Induces Prematureand Term Stillbirths in Pregnant Mice implication of oralbacteria in preterm birthrdquo Infection and Immunity vol 72 no4 pp 2272ndash2279 2004

[80] J Slots H S Reynolds and R J Genco ldquoActinobacillus acti-nomycetemcomitans in human periodontal disease a cross-sectional microbiological investigationrdquo Infection and Immu-nity vol 29 no 3 pp 1013ndash1020 1980

[81] T Kikuchi C L Hahn S Tanaka S E Barbour H ASchenkein and J G Tew ldquoDendritic cells stimulated with Acti-nobacillus actinomycetemcomitans elicit rapid gamma inter-feron responses by natural killer cellsrdquo Infection and Immunityvol 72 no 9 pp 5089ndash5096 2004

[82] S S Socransky and A D Haffajee ldquoThe bacterial etiology ofdestructive periodontal disease current conceptsrdquo Journal ofPeriodontology vol 63 no 4 pp 322ndash331 1992

[83] B Kramer M Kebschull M Nowak et al ldquoRole of the NKcell-activating receptor CRACC in periodontitisrdquo Infection andImmunity vol 81 no 3 pp 690ndash696 2013

[84] A Zeidel B Beilin I Yardeni E Mayburd G Smirnov andH Bessler ldquoImmune response in asymptomatic smokersrdquo ActaAnaesthesiologica Scandinavica vol 46 no 8 pp 959ndash9642002

[85] A Acikgoz F O Ozden T Fisgin et al ldquoOral and dental find-ings in Fanconirsquos anemiardquo Pediatric Hematology and Oncologyvol 22 no 6 pp 531ndash539 2005

[86] G A Justo M A Bitencourt R Pasquini et al ldquoImmune statusof Fanconi anemia patients decrease in T CD8 and CD56 dimCD16+ NK lymphocytesrdquo Annals of Hematology vol 93 no 5pp 761ndash767 2014

[87] K CMyers J J Bleesing SMDavies et al ldquoImpaired immunefunction in children with Fanconi anaemiardquo British Journal ofHaematology vol 154 no 2 pp 234ndash240 2011

[88] V J Rathod and N V Joshi ldquoPapillon-Lefevre syndrome areport of two casesrdquo Journal of Indian Society of Periodontologyvol 14 no 4 pp 275ndash278 2010

[89] T Lundgren R S Parhar S Renvert and D N TatakisldquoImpaired cytotoxicity in Papillon-Lefevre syndromerdquo Journalof Dental Research vol 84 no 5 pp 414ndash417 2005

[90] Y Li K To P Kanellakis et al ldquoCD4+ natural killer T cellspotently augment aortic root atherosclerosis by perforin-andgranzyme b-dependent cytotoxicityrdquo Circulation Research vol116 no 2 pp 245ndash254 2015

[91] Y V Bobryshev and R S A Lord ldquoIdentification of naturalkiller cells in human atherosclerotic plaquerdquoAtherosclerosis vol180 no 2 pp 423ndash427 2005

[92] S CWhitman D L Rateri S J SzilvassyW Yokoyama and ADaugherty ldquoDepletion of natural killer cell function decreasesatherosclerosis in low-density lipoprotein receptor null micerdquoArteriosclerosis Thrombosis and Vascular Biology vol 24 no6 pp 1049ndash1054 2004

[93] P Allavena G Bianchi D Zhou et al ldquoInduction of naturalkiller cell migration by monocyte chemotactic proteinminus1 minus2and minus3rdquo European Journal of Immunology vol 24 no 12 pp3233ndash3236 1994

[94] H Umehara E T Bloom T Okazaki Y Nagano O Yoshie andT Imai ldquoFractalkine in vascular biology from basic researchto clinical diseaserdquo Arteriosclerosis Thrombosis and VascularBiology vol 24 no 1 pp 34ndash40 2004

[95] D A Chistiakov I A Sobenin A N Orekhov and Y VBobryshev ldquoDendritic cells in atherosclerotic inflammation thecomplexity of functions and the peculiarities of pathophysio-logical effectsrdquo Frontiers in Physiology vol 5 article 00196 2014

[96] Z Mallat A Corbaz A Scoazec et al ldquoInterleukin-18interleukin-18 binding protein signaling modulatesatherosclerotic lesion development and stabilityrdquo Circulationresearch vol 89 no 7 pp E41ndashE45 2001

[97] K Uyemura L L Demer S C Castle et al ldquoCross-regulatoryroles of interleukin (IL)-12 and IL-10 in atherosclerosisrdquo Journalof Clinical Investigation vol 97 no 9 pp 2130ndash2138 1996


[98] A Selathurai V Deswaerte P Kanellakis et al ldquoNatural killer(NK) cells augment atherosclerosis by cytotoxic-dependentmechanismsrdquo Cardiovascular Research vol 102 no 1 pp 128ndash137 2014

[99] M F Linton A S Major and S Fazio ldquoProatherogenic roleforNKcells revealedrdquoArteriosclerosisThrombosis andVascularBiology vol 24 no 6 pp 992ndash994 2004

[100] K Dong J Ge S Gu et al ldquoOx-LDL can enhance theinteraction of mice natural killer cells and dendritic cells via theCD48-2B4 pathwayrdquo Heart and Vessels vol 26 no 6 pp 637ndash645 2011

[101] F Cheng L Twardowski K Reifenberg et al ldquoCombined BT and NK cell deficiency accelerates atherosclerosis in BALBcmicerdquo PLoS One vol 11 no 8 Article ID e0157311 2016

[102] I Bonaccorsi C De Pasquale S Campana et al ldquoNaturalkiller cells in the innate immunity network of atherosclerosisrdquoImmunology Letters vol 168 no 1 pp 51ndash57 2015

[103] K Kotfis J Biernawska M Zegan-Baranska andM ZukowskildquoPeripheral Blood Lymphocyte Subsets (CD4+ CD8+ T CellsNK Cells) in Patients with Cardiovascular and NeurologicalComplications after Carotid Endarterectomyrdquo InternationalJournal of Molecular Sciences vol 16 no 5 pp 10077ndash100942015

[104] H Bruunsgaard A N Pedersen M Schroll P Skinhoj and BK Pedersen ldquoDecreased natural killer cell activity is associatedwith atherosclerosis in elderly humansrdquo Experimental Gerontol-ogy vol 37 no 1 pp 127ndash136 2001

[105] L Jonasson K Backteman and J Ernerudh ldquoLoss of naturalkiller cell activity in patients with coronary artery diseaserdquoAtherosclerosis vol 183 no 2 pp 316ndash321 2005

Submit your manuscripts athttpswwwhindawicom

Stem CellsInternational

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014


MEDIATORSINFLAMMATION

of


Behavioural Neurology

EndocrinologyInternational Journal of



Disease Markers


BioMed Research International

OncologyJournal of



Oxidative Medicine and Cellular Longevity


PPAR Research

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Immunology ResearchHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

ObesityJournal of



Computational and Mathematical Methods in Medicine

OphthalmologyJournal of


Diabetes ResearchJournal of



Research and TreatmentAIDS


Gastroenterology Research and Practice


Parkinsonrsquos Disease

Evidence-Based Complementary and Alternative Medicine

Volume 2014Hindawi Publishing Corporationhttpwwwhindawicom


CD56CD16

Cytokines

KIRs

Perforin

Granzymes

NKG2D

CD56dimCD16+

(a)

CD56CD16 NKG2A

TNFs

IFNs

IL‐10

NKG2D

CD56brightCD16minus

(b)

CD56

VEGF

KIRs

NKG2D

CD9

CD49a

PLGFSDF‐1IL‐8

CD56superbrightCD16minus

(c)

Figure 1 Different human NK subsets Three different NK subsets have been characterized on the basis of distinctive surface antigenexpression and described as (a) CD56dimCD16+ that represents the conventional cytotoxic NKs characterized by the high release of perforinand granzymes (b) CD56brightCD16minus that are able to release a large amount of cytokines (c) CD56superbrightCD16minus that are able to produceproangiogenic factors including VEGF IL-8 and SDF-1 and are characterized by the expression of specific surface markers as CD9 andCD49a

on the target cell surface acting as activatory ligands NKcells are equipped with surface receptors that trigger cellactivation (immunoreceptor tyrosine-based activationmotifs(ITAM)) or inhibition (immune tyrosine-based inhibitorymotifs (ITIM)) [16] NK cells also directly contribute toadaptive immune responses interacting with DCs and bytriggering T cell responses Induction of DC maturation toproduce TNF-120572 and IL-12 and upregulation of costimulatoryligands are triggered by NK cells [17] Moreover NK cellsproliferate and acquire cytotoxic activity and the capacityto produce IFN-120574 through the interaction with DCs [18]Apart from activation of other cells of innate immunityNK cells also enhance induction of CD8+ T cell responsesthat is influenced by NK-released IFN-120574 which promotesantigen processing and presentation to T cells and T helpertype 1 (Th1) cell polarization [19] Two major circulatinghuman NK cell subsets have been characterized based onthe expression of surface antigens CD56 an isoform of thehuman neural cell adhesion molecule and CD16 the low-affinity Fc receptor necessary for the antibody-dependentcellular cytotoxicity (ADCC) Peripheral NK cells are pre-dominantly CD56dimCD16+ cytotoxic NK cells acting mainlythrough the release of perforin a membrane pore-formingtoxin and granzyme which activates the apoptotic cascadeon target cells However approximately 5 of circulatingNK cells show a CD56brightCD16minus phenotype These cellscan produce high levels of some cytokines Upon activationCD56brightCD16minus NK cells release IFN-120574 and TNF-120572 andthey kill target cells more efficiently [20]Within the develop-ing decidua a third NK subset is found the decidual NK cell(dNK) dNK cells display a CD56superbrightCD16minus phenotype[21] and are closely linked with vascularization of the deciduain both humans and mice dNK cells physiologically produceVEGF PlGF and IL-8 are poorly cytotoxic and are associatedwith the induction of CD4+ T regulatory (Treg) cells [22 23](Figure 1)

2 Natural Killer Cells and Cancer

Strong evidences suggest that the presence of inflammatorycells within the tumour microenvironment (TME) plays acrucial role in the development andor progression of humancancers [10 12 24ndash27] Among the host-dependent biologicalfeatures of the tumour hallmarks defined by Hanahan andWeinberg [28] there are ldquoevading immune destructionrdquo andldquotumour-promoting inflammationrdquo which together with theimmune orchestration of angiogenesis point out the key roleof the immune system in neoplastic diseases [9 10 12 24]

Alterations in NK cell activity have been describedin different type of cancer and are associated with theinduction of a tolerogenic and lesspoor cytotoxic func-tions with decreased expression of the activatory receptorNKG2D altered degranulation and release of perforin andgranzyme Recently Bruno et al identified a new NK cellsubset in tissue and peripheral blood of non-small-celllung cancer (NSCLC) patients termed respectively tumourinfiltrating (TINKs) and tumour associated (TANKs) NKswhich are able to promote angiogenesis [29 30] NSCLCTINKTANKs are characterized by a decidual like pheno-type CD56brightCD16minusVEGFhighPlGFhighIL-8+IFN-120574low ableto promote endothelial cell migration and induction ofcapillary-like structures [29 30]

Several TME released components including TGF-120573hypoxia and adenosine mostly shared with the decidualtissues are implicated in NK cell response against tumours[31] (Figure 2)

TGF-120573 is one of the numerous TME factors involvedin the induction of immune cell polarization [32] and isexpressed at high levels both in the tumour microenvi-ronment and in the decidua [29] During carcinogenesisTGF-120573 acts as a tumour suppressor by inhibiting tumourcell replication and favouring apoptosis [33 34] while atlater stages of tumour progression it exerts protumourigenic


CD56

CD16

Cytokines

KIRs

Perforin

Granzymes

NKG2D

Adenosine

Hypoxia

H+

H+H+

H+H+

H+

Acidity

TGF‐120573

TEXOs

CD56

VEGF

KIRs

NKG2D

CD9

CD49a

PLGFSDF‐1IL‐8

O2

O2

O2

O2


















cells

Lysis

CVB4


(a)

120572-CTLA 4

High NK number

Insulitis

NK cells

Lysis

(b)

NKs

Autoreactive CTL

NODSCID CFA

Inhibition

NK cells

CD3minusDX5+

T cells

(c)


(d)










P gingivalis


NKp46

PGE2PGE2MMPs


NKs

Osteoblast

Osteoclast

Dendritic cells

IL‐12

NKs

CRACC

Dendritic cells


F nucleatum


F nucleatum

PGE2

AB E

C

D

osteoprotegerin
























IL‐12CD56CD16

KIRs

PerforinGranzymes


Smooth muscle cells

NK cells


Debris

Cholesterol


CD56CD16

KIRsNKG2D

NK cells


MΦ

IFN‐120574

IFN‐120574

IFN‐120574

IFN‐120574

(a)



reduction

(b)

120572-Asialo‐GM1

NK depletion


NK


cells

(c)

Spleen


NKcells

NK transfer


(d)




6 Conclusion



Abbreviations












Disclosure







Acknowledgments


References




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















CD56

CD16

Cytokines

KIRs

Perforin

Granzymes

NKG2D

Adenosine

Hypoxia

H+

H+H+

H+H+

H+

Acidity

TGF‐120573

TEXOs

CD56

VEGF

KIRs

NKG2D

CD9

CD49a

PLGFSDF‐1IL‐8

O2

O2

O2

O2


















cells

Lysis

CVB4


(a)

120572-CTLA 4

High NK number

Insulitis

NK cells

Lysis

(b)

NKs

Autoreactive CTL

NODSCID CFA

Inhibition

NK cells

CD3minusDX5+

T cells

(c)


(d)










P gingivalis


NKp46

PGE2PGE2MMPs


NKs

Osteoblast

Osteoclast

Dendritic cells

IL‐12

NKs

CRACC

Dendritic cells


F nucleatum


F nucleatum

PGE2

AB E

C

D

osteoprotegerin
























IL‐12CD56CD16

KIRs

PerforinGranzymes


Smooth muscle cells

NK cells


Debris

Cholesterol


CD56CD16

KIRsNKG2D

NK cells


MΦ

IFN‐120574

IFN‐120574

IFN‐120574

IFN‐120574

(a)



reduction

(b)

120572-Asialo‐GM1

NK depletion


NK


cells

(c)

Spleen


NKcells

NK transfer


(d)




6 Conclusion



Abbreviations












Disclosure







Acknowledgments


References




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of





























cells

Lysis

CVB4


(a)

120572-CTLA 4

High NK number

Insulitis

NK cells

Lysis

(b)

NKs

Autoreactive CTL

NODSCID CFA

Inhibition

NK cells

CD3minusDX5+

T cells

(c)


(d)










P gingivalis


NKp46

PGE2PGE2MMPs


NKs

Osteoblast

Osteoclast

Dendritic cells

IL‐12

NKs

CRACC

Dendritic cells


F nucleatum


F nucleatum

PGE2

AB E

C

D

osteoprotegerin
























IL‐12CD56CD16

KIRs

PerforinGranzymes


Smooth muscle cells

NK cells


Debris

Cholesterol


CD56CD16

KIRsNKG2D

NK cells


MΦ

IFN‐120574

IFN‐120574

IFN‐120574

IFN‐120574

(a)



reduction

(b)

120572-Asialo‐GM1

NK depletion


NK


cells

(c)

Spleen


NKcells

NK transfer


(d)




6 Conclusion



Abbreviations












Disclosure







Acknowledgments


References




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















P gingivalis


NKp46

PGE2PGE2MMPs


NKs

Osteoblast

Osteoclast

Dendritic cells

IL‐12

NKs

CRACC

Dendritic cells


F nucleatum


F nucleatum

PGE2

AB E

C

D

osteoprotegerin
























IL‐12CD56CD16

KIRs

PerforinGranzymes


Smooth muscle cells

NK cells


Debris

Cholesterol


CD56CD16

KIRsNKG2D

NK cells


MΦ

IFN‐120574

IFN‐120574

IFN‐120574

IFN‐120574

(a)



reduction

(b)

120572-Asialo‐GM1

NK depletion


NK


cells

(c)

Spleen


NKcells

NK transfer


(d)




6 Conclusion



Abbreviations












Disclosure







Acknowledgments


References




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of































IL‐12CD56CD16

KIRs

PerforinGranzymes


Smooth muscle cells

NK cells


Debris

Cholesterol


CD56CD16

KIRsNKG2D

NK cells


MΦ

IFN‐120574

IFN‐120574

IFN‐120574

IFN‐120574

(a)



reduction

(b)

120572-Asialo‐GM1

NK depletion


NK


cells

(c)

Spleen


NKcells

NK transfer


(d)




6 Conclusion



Abbreviations












Disclosure







Acknowledgments


References




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of


















6 Conclusion



Abbreviations












Disclosure







Acknowledgments


References




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of

















Acknowledgments


References




















































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
































































































of






Disease Markers



OncologyJournal of





PPAR Research



Journal of

ObesityJournal of
















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