1 phm142 metabolic biochemistry and immunology ii white cells chemical warfare lecture outline...
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PHM142 Metabolic Biochemistry and Immunology II WHITE CELLS
CHEMICAL WARFARE lecture outline
1) Molecular mechanisms of leukocyte function• Rheumatoid arthritis• CGD disease
2) Eosinophils
3) Macrophages • Function• Growth factors and cytokines• But – macrophage - induced tissue injury• Multiple organ failure, ARDS, sepsis
2Blood CellsType of cell
Red blood cells (erythrocytes)
White blood cells (leukocytes) polymorphonuclear/granular leukocytesNeutrophils (50 60%)Eosinophils (1 4%)
Basophils (0.5 2%)
mononuclear leukocytes
Lymphocytes (20 40%)
Monocytes (2 9%) ( macrophages in extravascular tissue)Killer cells
Megakaryocytes ( platelets)
Main function
Transport O2 and CO2
Destroy invading bacteria
Phagocytose & kill invading antigensDestroy parasites and modulate allergic inflammatory reactionsRelease histamine, serotonin, bradykinin, heparin, and cytokines; converts arachidonic acid to prostaglandins & leukotrienes
(T & B) mediate cytokine release
Phagocytose & kill ingested microbes Kill virally infected cells and tumor cells (offer “natural” immunity as well as adaptive)Initiate blood clotting; also release histamine and serotonin
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Thin sections of the major types of white blood cells (leukocytes) foundin the circulation, showing the variety of internal structures observed.
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Macrophage3
4Molecular mechanisms of neutrophil functionAmer J Med. 109, 33-44 (2000)
Neutrophil membrane electron transport
CYTOSOL
PHAGOSOME MEMBRANE
PHAGOSOME VACUOLE
H2O2
H2O
GSH
GSSG
NADP+
NADPH
Glucose
glucose-6-phosphate
glucose-6-phosphatedehydrogenase
6 P gluconic acid
H2O2 O2.-
O2
NADP+
NADPH
Glucose-6-P
Gluconic acid
NADPHoxidase
Intracellularly in white cells
H2O2 + Cl- HOCl Bactericidalmyeloperoxidase
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2
2
Fe2+
Inflammation or infection
MPO(myeloperoxidase), HOCl(hypochlorite), SOD (superoxide dismutase).
HOCl + red cell GSH = GSH cyclic sulfonamide (biomarker for HOCl formation in vivo that reflects inflammation (oxidant formed by neutrophils))
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Living with a killer: The effects of hypochlorite on mammalian cellsIUMB Life 50,259-266 (2000) ; Chem.Res.Toxicol.21,1011-6 (2008)
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A CGD disease clinical test for the lack of leukocyte respiratory burst.
Oxygen in solution is measured by an O2 electrode
O2 O2.-
H2O2
Fe2+-Cyt b558 Fe3+-Cyt b558
FAD+ FADH2
FAD
NADPH NADP+
Killsbacteria
Superoxide dismutase
No O2 consumption by CGD patient’s leukcoytes.
Oxygen uptake is insensitive to cyanide
Opsonized bacteria or N-formyl methionine peptide
Leukocytes (from normal patient)
O2 l
evel
in s
olut
ion
Time
Leukocyte Respiratory burst byphagosome membr. elect. transport.
superoxide detected by NBT reduction to formazan (blue precipitate).
*
* Made by bacteria; recognized by mammalian cells as foreign.
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Trends in Biochem.Sci. 2, 63 (1977)
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Activation of leukocyte NADPH oxidase (Nox) showing assembly of the enzyme and fusion of the oxidase-containing vesicle with the phagosomal membrane.
Babior, 2000. American Journal of Medicine. 109:33 44.
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NADPH oxidase (Nox)activation
Proton Channel Function
Medicine 79, 170-200 (2000)
b558
+ H+
ProtonChannel
(phosphorylationby kinase)
gp91phox is b558 with proton channel (or K+?)
phox is “phagocyte oxidase”
membrane
Vacuolar space
b558
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bact.
• CGD can kill Bacteria that produce H2O2 and have low catalase activity, e.g., streptococci.• But can’t kill bacteria which have high catalase activity or low H2O2 production, e.g., serratia, nocardia, and aspergillus; fungal, staphylococcus, burkholderia (pneumonia, sepsis).
Chronic Granulomatous Disease (CGD)
NADPH OXIDASE DEFICIENCY
White Cell
0.1 M Chloridein blood
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1. Two-thirds have mutations in gp91phox gene Unable to form H2O2.i.e., no cyanide resistant respiratory burst & don’t live beyond childhoodHave X-linked chromosomal deficiency
Have no cyt. b558 functionb-subunit – 91kD – glycosylated – X chromosome DEFECTa-subunit – 22kD – normal chromosome 16
CGD patients have mutation in p47phox gene (reach adulthood)Have autosomal recessive deficiency
2. CGD patients have no cytosol activating protein that phosphorylates and activates NADPH oxidase which causes translocation of the oxidase from the endoplasmic reticulum to the plasma membrane.
LEUKOCYTE ELECTRON TRANSPORTChronic granulomatous disease (CGD)
Medicine 79, 170 200 (2000); J Leukocyte Biol. 69, 191 6, 2001
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1. Prophylaxis with trimethoprim-sulfamethoxazole and interferon gamma2. Bone marrow transplantation or granulocyte transfusion (with severe
infections)3. Hemopoietic stem cell gene therapy (retrovirus-mediated expression of gp91phox to
reconstitute NADPH oxidase – Dinauer et al., 1999. Blood. 94(3):914-22)..
4. Possible Pharmaceutical Therapy?
Opsin + Chemoattractant
Polystyrene Beads
Glucose oxidase (Fungal)
Glucose + O2 H2O2
THERAPY FOR CGD DISEASE
NADPH oxidase family: tissue locationJ.Biol.Chem 283,16961-16965(2008)
• NOX1 colon>prostate,uterus,breast,macrophage?
• NOX2 phagocyte H2O2 for MPO >> hepatocyte,B lymphocyte, cardiomyocytes,endothelial cells
• NOX3 inner ear,fetal
• NOX4 kidney,blood vessels,cardiomyocytes,endoth.
• NOX5 lymphoid tissue,testis
• Duox1 & 2 (dual oxidase) makes thyroxine hormone and H2O2 for thyroid peroxidase TPO >lung,GI
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leukocytes
Synovium (synovial fluid)
From Am J Med. (2000). 190:33-44
Rheumatoid Arthritis is an autoimmune inflammatory disease that may affect (skin, blood vessels, heart, lungs, muscles-- but principally attacks joints (proliferative synovitis progressing to cartilage destruction/joint ankylosis.
Pathogenesis (unknown etiology):genetic susceptibility; joint damage mediated by leukocytes or exogenous arthritogen (virus, mycobacteria).
Babior, 2000. American Journal of Medicine. 109:33 44.
NSAID Drug therapy for RA or OAIBUPROPHEN COX-1 inhib. 300mg 3 times pd
Cardiovascular & GI bleeding risk,inhib platelets, kidney/liver tox.
ALEVE (Naproxen) 200mg otc ; lasts 12h
• Inhibits inflammation , COX-I and COX-2 inhibitor
• Decrease pain, temp, muscle pain, menstrual cramps
• Lower stroke risk than ibuprofen; high dose risk GI bleed.
VIOXX COX-2 inhibitor for OA,RA 1999 introd.
• 2004 (withdrawn due to heart attack,stroke). Late?
CELEBREX (celecoxib)1998 COX-2 inhibitor 400mg
• low cardiorenal tox, platelet effects & GI bleeding
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Side effects of COX-1 inhibitors• e.g. Aspirin may cause stomach bleeding and risk
GI ulcer formation.
• molecular mechanism of bleeding/ulcers unknown.
• Aspirin causes stomach cell mitochondrial uncoupling and acidosis.
• inhibits COX-1 activity thereby increasing tissue unsat. fatty acid levels and cause acidosis.
• decreases PGE2 levels that protect stomach membr.
• inhibits thromboxane formn. and platelet aggreg. • unsat.fatty acid + PGS attacks protective mucous layer
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Mechanism of NSAID induced GI toxicity
• Stage I NSAIDs decrease intestinal mucosal prostanoids (PGE,TXB2, 6-keto-PGF)
• Mitochondrial uncouplers (e.g.indomethacin,DNP) compromised intestinal barrier). Resp.inhibited
• Stage 2 mild inflammation + aspirin
• Stage 3 histopathology, ulcers and bleeding
• Rat model: ulcers, intestinal inflammation or gastric permeability induced by indomethacin or DNP + Cox inhib (aspirin).
Aliment Pharmacol. Ther. (2000) 14,639-650
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19Rheumatoid Arthritis Therapy
Repetitive hypoxia in joints, and endothelial cells
ATP hydrolysis
Hypoxanthine from ATP
ROS
Reperfusion O2 +endothelial cell xanthine oxidase
ALLOPURINOLinhib.
endothelial cell nitric oxide
peroxynitriteDestruction of joint
Uric acidMonosodium urate crystals in joint
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Anti-Inflammation therapy
• ROS Scavenger Therapy SOD, selenomethionine/Vit E, 5-aminosalicylate, penicillamine:Cu • Macrophage inhibitor therapy: Gold thiomalate or auranofin or zinc or copper salicylate• Prostaglandin Synthetase Inhibitors:-(NSAIDS) COX-1 many cells e.g.aspirin,ibuprofen, but GI bleeding,kidney COX-2 inflammatory cells e.g. VIOXX (withdrawn), CELEBREX but
cardiovascular problems.• “Biologics” antibodies that inhibit inflammatory cytokines e.g.TNF-α• Diet: decrease arachidonate intake (meat), increase omega 3 fatty acids (fish)
decreases bad prostaglandins, decrease Fe intake References: Semin. Arthritis Rheum. 27: 366-70 (1998). Autoimmunity Reviews 7,1-7(2007) Anti-inflammatory Biologics
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EOSINOPHILS: (chemical warfare cont.)
Accumulate in parasite infection, asthma, rheumatoid diseases, Hodgkin’s lymphoma and allergic or inflammatory diseases
1)destroy parasitic worms, tumor cells, fungi and bacteria by forming hypobromite
H2O2 + Br- + H+ HOBr (hypobromite) + H2O
2) cytokine production e.g. PAF, LTC4 unlike neutrophils (leukocytes) .
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Biochem J. 358, 233-239 (2001).
MPO
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MACROPHAGES - chemical warfare function
1) Endocytosis and exocytosis via specific receptors for IgG and C3 coated in bacteria2) H2O2 production by NADPH oxidase to kill mycobacteria3) Arachidonate oxidation to prostaglandin4) Cytokine production - upon activation by PDGF a) lipopolysaccharide (endotoxin) TNF- b) immune system activation BCG infection IL-1 c) inflammation or interferon (IFN-) PAF TGF and arginine nitric oxide kill tumor cells
5) endocytosis and delivery to lysosomes (via scavenger receptor) of oxidised LDL (low density lipoprotein) - can result in transformation to foam cell (the basis of the formation of atherosclerotic plaque)
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24SURGERY TRAUMA
e.g. if intestinal surgery causes prolonged interrupted blood flow (reperfusion injury)
EARLY ORGAN FAILURE if endotoxin from Gram –ve cell wall of Gram-ve bacteria in the intestine crosses gut barrier
Endotoxin releases immune cell growth factors &humoral/cellular mediators (now too late!)
e.g. TNF, IL, arachidonic oxidation production
Attract PMN, macrophages, endothelium cells which further release TNF,NO,H2O2
anaphylactic shock mast cells release histamine
(e.g. ARDS (adult respiratory distress syndrome), hepatitisMultiorgan failure, sudden death
Harrison 2007 “Principles of Medicine”
Tumor Necrosis Factor (TNFα) as the primary trigger for
inflammatory response
Macrophages,monocytes,lymphocytes,keratinocyte
• TNFα incr in chronic inflammatory diseases:
rheumatism,arthritis,encephalitis,tumors Rheumatoid arthritis , psoriasis,Crohn’s disease
• Proinflammatory > antiinflammatory cytokines• Drug therapy: NSAIDs, GC glucocorticoids, Disease Modifying
Antirheumatic Drugs (DMARDs).
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Drug induced hepatocyte cytotoxicity caused by activated immune cells releasing cytokines and reactive oxygen species
(Kupffer cells , macrophages ,neutrophils) i
1) Toxic doses of drugs or chemicals injure hepatocytes. Injured hepatocytes release factors that attract Kupffer cells to specificregions of the liver. 2) Additional mononuclear phagocytes are also recruited from blood and bone marrow precursors. 3) Once localised in the liver, the macrophages become activated by hepatocyte-derived factors of endothelial cells. 4) Activated macrophages and endothelial cells release cytokines e.g.TNFα & platelet activating factor prime & activate Kupffer cells which release Reactive Oxygen Species and more cytokines. 5) Some chemoattractants and cytokines can attract and activate neutrophils that also contribute to hepatocyte injury.
27Macrophages and Tissue Injury
Toxicant
Target tissues
Activated macrophagese.g. Kupffer cells
Mediators
Cytotoxicity Amplification
Model for the role of macrophages in tissue injury by generating inflammatory mediators.
Gold thiomalateGadolinium chloride(macrophage inhibitor)
Tissue Injury
Macrophage killing mechanism
• Macrophages endocytose & present antigens to T cells as foreign substances
• Exocytose (via specific receptors) IgC and C3 coated bacteria
• Produce H2O2 to kill mycobacteria
• Produce cytokines PDGF,PAF,TNFα & β, IL1 convert arginine to NO
• Prevents foam cell formation by endocytosis of oxid. LDL by macrophage oxid LDL & fusion with lysosomes and digestion by cathepsins & Plipases.
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H2O2
MPO
NEUTROPHIL or KUPFFER CELL
DRUG
RadicalH2O2
PeroxidaseDrug
HepatocyteOxidative Stress
NECROSISAPOPTOSIS
DRUGGSHGSor
Ascorbate Cooxidation
LIPID PEROXIDATION
Mitochondria
INFLAMMATION MODEL FOR IDIOSYNCRATIC DRUG TOXICITY (Liver injury, bone marrow agranulocytosis, lung toxicity)
O’Brien et. al. Drug Discovery Today 2005 10, 617-625
30Table 2: Inflammatory mediators implicated in toxicity Toxicant
Mediator Lung Liver
1) Reactive oxygen intermediates Ozone Endotoxin (H2O2, .OH) Asbestos Acetaminophen
Amiodarone Corynebacterium parvum Reactive nitrogen intermediates Bleomycin Galactosamine (peroxynitrite) Carbon tetrachloride
1,2-dichlorobenzenePhenobarbitalEndotoxin
2) Hydrolytic enzymes Endotoxin (collagenase, elastase) Silica 3) Lipids Hyperoxia (leukotrienes, prostaglandins, thromboxanes)
4) IL-1 Cigarette smoke
5) TNF- (mitochondrial toxin, Cadmium chloride Alcohol reactive oxygen species)
Toxicology 160, 111 8 (2001).Ann. Rev. Pharmacol. Toxicol. 35, 655 (1995).
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Table 1: Toxicants whose pathophysiology is thought to be associated with macrophages and inflammatory mediators
Pulmonary toxicants Hepatotoxicants
Ozone AcetaminophenSulfuric acid Carbon tetrachlorideNitrogen dioxide LipopolysaccharideCigarette smoke GalactosamineHyperoxia 1,2-dichlorobenzeneBleomycin CadmiumAmiodarone Allyl alcoholTitanium dioxide EndotoxinSilicaAsbestosCadmium chloride
32Autoimmune disease drug therapy1. Alkylating Agents (anticancer cytostatic drugs) Inhibit cell division of both T cells and B cell (lymphocytes) • Cyclophosphamide, nitrosoureas, platinum compounds Efficient therapy for systemic lupus, autoimmune hemolytic anemias,
Wegener’s
2. Antimetabolites Interfere with synthesis of nucleic acids - a) Folic acid analogues (METHOTREXATE) binds dihydrofolate reductase
and prevents synthesis of tetrahydrofolate. Used in treatment of autoimmune diseases (rheumatoid arthritis) and in transplantations
b)Purine analogues (AZATHIOPRINE, or MYCOPHENOLATE (CellCept) inhib. IMP dehydrogenase and GMP synth. Treatment of autoimmune diseases (Wegeners,psoriasis ) also prevents transplant rejection. Mercaptopurine (leukemia,Crohns).
c)Pyrimidine analogues LEFLUNOMIDE
3. Cytotoxic anticancer e.g. mithramycin, dactinomycin inhibits RNA transcription and DNA replication
4. Biologics: anti-cytokine antibodies • TNFalfa blockers1)Etanercept for RA 2)Infliximab
(remicade) for Crohns disease,colon cancer a chimeric human Fab.
3) Adalimumab (Humira) a humanised monoclonal for colon cancer,macular degen. 4)Stelera NEW for psoriasis, 5 shots p.a.$50K
• Rituximab kills CD20 B cell NH lymphomas,RA • Abatacept,fusion protein inhib.T cell costim.RA
• Avastin (bevacizumab) inhib.VEGF-A (vascular endoth.growth factor) glioblastoma,macular degen.
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T lymphocytes formed in b.m.& mature in thymus
1) T helper cells help B cells mature into plasma cells.
CD4+T cells express CD4 protein on their surface2)19% Cytotoxic T cells destroy viral infective & tumor cells
3)Memory Tcells CD4+(lost in AIDs) or CD8+(cytotoxic)
subset of antigen T cells that persist long after infection.
4) Regulatory T cells (suppressor T cells)
5)Natural killer (NK) largest T cell.Interferons cause
cytotoxic granule release
6) Antigen-presenting cell (APC)
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B cells bursa of fabricius(birds)
• Plasma cells are large B cells exposed to antigens which produce antibodies that bind to microbes. In tissues not plasma.
• Contain rough e.r. & cell rapid apoptosis (short life)
• Memory B cells formed from activ.B cells(long life)
• 23% B-1 cells IgM>IgG in peritoneal & pleural cavities
• B-2 cells
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Immunosuppressants and anti-inflammatories RA
• B cell depleting agents like rituximab
• tocilizumab human monoclonal antibody against IL-6R cytokine
No truly effective therapies exist
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Biomarkers for inflammation diseasePro-inflammatory cytokines
• Elevated CRP,IL-1B,IL-1B,IL-6,IL-8
• Tumor necrosis factor alpha
• c-ANCA antineutrophil cytoplasmic stain
• p-ANCA antineutrophil perinuclear stain
• x-ANCA chronic inflammatory bowel disease
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Biomarkers for determining oxidative stress associated with diseases
• 1) Plasma lipid hydroperoxide
• 2) Oxidative DNA damage DNA 8-OHdQ
• Urinary 8-OHdQ
• Thymine oxidation HMdU
• DNA strand breaks (Comet assay)
• 3) Protein carbonyls using dinitrophenylhydrazine
• Protein oxidation,cysteine,methionine,histidine
• Protein AGEs
• 4) Fructose oxidation forms toxic glyoxal
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Celiac disease (dietary autoimmune)• Small intestine inflammation caused by an immune
reaction to gliadin, a gluten protein, found in wheat,barley,rye (bread).
• Blunting of villi, damage to inner surface , lymphocyte infiltration of crypts.
• Abdominal pain and diarrhea.
• Impaired vitamin uptake (brain,nervous,bone,liver)
• Treatment life long gluten free diet
• 1:>105-1:750 starting middle infancy
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• White blood cells within tissue, have a role in innate and adaptive immunity
• They engulf pathogens and debris via phagocytosis, and move around via amoeboid movement
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• When a pathogen (can be self in this case) is ingested by a macrophage, pathogen proteins attach it to class II MHC
• Macrophage activated to deliver signals to T-cells which produces autocrines and stimulate their own production
• Helper T cells activate B cells which produce antibodies that inhibit the pathogens
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• Results from a loss of immunological tolerance – which is the ability to ignore self-antigens
• T and B lymphocytes that recognize self-antigens are usually destroyed in the Thymus and Bone marrow, respectively, preventing autoimmunity.
• Infection and overstimulation of APCs can break tolerance and induce priming of T-cells
• A combination of genetics and environment are responsible for autoimmune disease
• Human Lymphocyte Antigen (HLA/MHC) is the best predictor as it enhances antigen presentation resulting in increased T-cell activation
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Antibody-mediated (B cells)
• Binding of antigens on the surfaces of B-cells produces antibodies
• Autoantibodies:
– Bind to self-tissue, and activates the complement cascade which targets the self-antigen to be phagocytosed (opsonized) by Macrophages
Cell-mediated (T cells)• Immune cells both kill
cells directly and indirectly via cytokines (PG, NO, etc.)
• Macrophages: – INITIATE the response
as antigen presenting cells
– PARTAKE in killing cells through antibody dependent-dependent cell-mediated cytotoxicity and by releasing cytokines (TNF and IL-1)
– PRESENT SELF-TISSUE TO T CELLS
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II White (Immune) Cells
• THE END
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