ttp, ahus and tma: spectrum of one disease or different ... · spectrum of one disease or different...
TRANSCRIPT
TTP, aHUS and TMA:
Spectrum of One Disease or Different Diseases?
Han-Mou Tsai, M.D.
Hematology, E-Da Hospital
Schistocytes in Microangiopathic Hemolytic Anemia (MAHA)
Thrombotic Thrombocytopenic Purpura: A Brief History of Therapeutic Advances
• Moschcowitz, 1924
– MAHA, thrombocytopenia, neurological deficits and other symptoms
– Widespread arteriolar and capillary thrombi at autopsy
• Byrne et al and Bukowski, 1976
– Plasma transfusion and plasma exchange resulted in high rates of remission and survival
• Rock GA et al, 1991
– Plasma exchange: 80% survival rate at 6 months
– Plasma infusion: 60% survival rate at 6 months
Challenges in TTP
• What causes the disease?
• Why is plasma exchange effective?
• How to improve the outcome?
• How to simply the treatment?
Deficiency of ADAMTS13 in TTP
TTP Treat Rem
Patient plasma
VW
F c
lea
vin
g a
cti
vit
y (
% o
f c
on
tro
l)
Tsai HM & Lien E C-Y, N Engl J Med 1998;339:1585
Random Misc HIT
Control plasma
VW
F c
lea
vin
g a
cti
vit
y (
% o
f c
on
tro
l)
Misc TTP Rem
Patient + normal plasma
VW
F c
lea
vin
g a
cti
vit
y (
% o
f c
on
tro
l)
= 5 cases
= 1 case
Families with Hereditary Deficiency of VWF Cleaving Protease
1 2 0.67 0.57
1 2 3 4 5 6 7
0.06 0.02 0.63 0.60 0.97 0.45 0.64
II
I 1 2
1 2
I
II
B
1 2
1 2 3 4 0.07 0.55 0.55 0.62
0.58 0.59
I
II
C D
1.02 0.61 0.80 1.04 0.63 0.90 0.92 1.09 0.97 1.04 0.53 0.65
0.64 0.05 0.05 0.57 1.01 0.63 0.65 0.06 0.98
0.68
1 1.16
2 1 3 4 6 7 8 9 10 11 13
1 2 3 4 5 6
III
II 5 12
A
0.53 0.51
0.06 0.48
7
I
8 9
Levy G et al, Nature 2001;413:488
Patients of Hereditary TTP and Their Family Members
0.0 0.5 1.0 1.5
Protease level (U/mL)
Normal individuals
Patients and family members
Patient
Obligate carrier
At risk
Not at risk
0.0 0.5 1.0 1.5
Protease level (U/mL)
Levy G et al, Nature 2001;413:488
Signal
PrP MP Disintegrin
TSR
Cys
TSR CUB
Spacer
HEIGHSFGLEHD
1 1427
RGDS
Non-sense
Mis-sense
Deletion/
insertion
Splice
ADAMTS13: Structure And Mutations
Q44X
H96D
R102C
V108M
R193W
T196I L232Q
D235H
718-724del
A250V
S263C
R268P
C311Y P353L
W390X
R398H
Q449X
P457L
C508Y
R528G
1873-4del
I673F
R692C
A732V
2279del
2376-2401del
2549-2550del
C908Y
R910X
C951G
C1024G
R1034X
R1123C R1123H
C1213Y
W1245X
3769-3770insT
R1336W
4143-4144insA
331+1 414+1
686+1
687-2 1244+2
1584+5
R910X
W390C
I79M
S203P
R507Q
A596V C758R
C908S
R1096X
R1060W
2930-5del 3252-3del
29bp-del
Intron12
Levy G et al, Nature 2001 + others
Shear Stress Increases the Adhesive Activity of VWF In TTP Plasma
50
150
200
vW
F R
Cof (%
)
100
0 2500 5000 7500
Shear rate (sec-1)
vWF/TTP
vWF/NP
Tsai HM & Lien EC-Y, N Engl J Med 1998;339:1585
ADAMTS13
Normal circulation
Shear ADAMTS13
vWF ADAMTS13
Platelet Shear Shear
EC
Subendothelial matrix
Subendothelial matrix
EC
Platelet
Unfolded vWF
ADAMTS13 deficiency
vWF
Shear stress
Platelet
Subendothelial matrix
Subendothelial matrix
EC
EC
Subendothelial matrix
Unfolded vWF
At sites of microvascular injury
Shear rate Flow velocity 0
Vessel injury
EC
Subendothelial matrix
Subendothelial matrix
EC
Platelet
VWF
ADAMTS13
Mechanism of Microvascular Thrombosis in ADAMTS13 Deficiency
Tsai HM, Am J Med 2013;126:200-209
vWF
ADAMTS13
Platelet
TTP: Arteriolar and Capillary Thrombosis
Heart Kidney
Tsai HM, Am J Med 2013;126:200-209
Brain Brain
P&F
Impact of ADAMTS13 Discovery
• A molecular basis for the diagnosis of TTP – Distinction from other disorders of MAHA
– Subclinical and incomplete forms of TTP
• An immunological basis for
– Tracking the development of relapse
• A biological basis for plasma therapy – Replenishment of ADAMTS13
– Removal of ADAMTS13 inhibitors (by plasma exchange)
• New directions of therapeutic development
– Immunosuppressive therapy
• Rituximab
• Cyclosporin A
• Proteosome inhibitors (e.g. bortezomab)
• Anti-BAFF (e.g. belimumab)
– Recombinant ADAMTS13
• Non-suppressible variants of ADAMTS13
– Blockers of VWF-platelet binding
• Anti-VWF aptamer (e.g. ARC1799)
• Anti-VWF antibodies (e.g. nanobody ALX-8100
Variable Course of ADAMTS13 Autoimmunity in TTP
1
2
3
ADAMTS13
ADAMTS13 <10%
Symptomatic
Time
AD
AM
TS
13
in
hib
ito
r le
ve
l
Persistent disease
Time
AD
AM
TS
13
in
hib
ito
r le
ve
l
Brief duration
Time
AD
AM
TS
13
in
hib
ito
r le
ve
l
Relapse
Time
AD
AM
TS
13
in
hib
ito
r le
ve
l
A Case of Recurrent and Protracted TTP
Yomtovian R et al, Brit J Haematol 2004;124:787
Rituximab Suppresses ADAMTS13 Inhibitors
Rituximab
Yomtovian R et al, Brit J Haematol 2004;124:787
Sustained Remission of TTP Following Rituximab
Rituximab
Yomtovian R et al, Brit J Haematol 2004;124:787
Early Death of TTP
PEx
EF = 30% Death
Personal unpublished data
Early Relapse and Death
PEx PEx
Personal unpublished data
Inhibitor titer
Death due to Surging ADAMTS13 Inhibitors
Tsai HM, Sem Thromb Hemost 38:469, 2012
Death
Rituximab
Preemptive Rituximab for TTP
Rituximab ≤3 days
from admission, n = 52
Rituximab >3 days
from admission, n = 30 P
Death 2 2 P >0.05
Median No. of PEX to remission
(range) 16 (4–36) 24 (6–40) P = 0.03
Median time to remission from first
infusion, days (range) 10 (2–50) 9 (0–30) P = 0.67
Westwood J-P et al, J Thromb Haemost 2013;11:481
Rituximab ≤3 days
from admission, n = 52
Rituximab >3 days
from admission, n = 30 P
Death 2 2 P >0.05
Median No. of PEX to remission
(range) 16 (4–36) 24 (6–40) P = 0.03
Rituximab ≤3 days
from admission, n = 52
Rituximab >3 days
from admission, n = 30 P
Death 2 2 P >0.05
Consecutive Non-Referral TTP Cases at Montefiore, 1997-2006
HIV- group HIV+ group
Number of cases 26 13
No. of plasma exchange, median (range) 13 (3 – 42) 16 (7 – 39)
Follow-up duration, months, mean (SD) 53 (37) 39 (37)
Number of death (%)
During initial episode (TTP + not TTP)
After remission (TTP + not TTP)
2 (7.7%) (2+0)
2 (8.3%) (1+1)
2 (15.4%) (0+2)
1 (9.1%) (0+2)
Rituximab Decreases the Risk of TTP Relapse
Westwood J-P et al, J Thromb Haemost 2013;11: 481
Relapse-free survival (months)
Pro
po
rtio
n in
re
mis
sio
n
Early rituximab
Late rituximab
Long-Term Outcome of TTP
0 20 40 60 80 100 1200
20
40
60
80
100
HIV-
HIV+
Months
Overa
ll s
urv
ival
%
Overall survival
0 20 40 60 80 100 1200
20
40
60
80
100
HIV-
HIV+
MonthsR
ela
pse-f
ree s
urv
ival
%
Relapse free survival
Tsai HM, Hem Onc Clin NA 2013;27:565
ADAMTS13-Guided Rituximab for Prevention of TTP Relapse
Tsai HM, Hem Onc Clin NA 2013;27:565
No
rma
l ran
ge
Years from rituximab #1
Factors Affecting the Morbidity and Mortality of TTP
Process Consequence Measures
• Vital functions are affected • Death
• Blockers of VWF-platelet binding − Anti-VWF aptamers (e.g. ARC1799)
− Nano anti-VWF A1 (e.g. ALX8100)
• Non-suppressible rADAMTS13 variants
• High and/or persistent ADAMTS13
inhibitor levels
• Protracted course
• Death
• Preemptive rituximab?
• Blockers of VWF-platelet binding
• Non-suppressible rADAMTS13 variants
• Iatrogenic complications (e.g. line
sepsis)
• Increased morbidity
• Death • Specialized catheter team
• Fluctuation of autoimmune B-cell
clones • Relapse • ADAMTS13-guided rituximab
• Unrelated causes
− e.g. HCV liver cirrhosis, HIV
disease, recurrent breast cancer
• Determined by the
concurrent disease • Management of concurrent diseases
Process Consequence Measures
• Vital functions are affected • Death
• Blockers of VWF-platelet binding − Anti-VWF aptamers (e.g. ARC1799)
− Nano anti-VWF A1 (e.g. ALX8100)
• Non-suppressible rADAMTS13 variants
• High and/or persistent ADAMTS13
inhibitor levels
• Protracted course
• Death
• Preemptive rituximab?
• Blockers of VWF-platelet binding
• Non-suppressible rADAMTS13 variants
• Iatrogenic complications (e.g. line
sepsis)
• Increased morbidity
• Death • Specialized catheter team
• Fluctuation of autoimmune B-cell
clones • Relapse • ADAMTS13-guided rituximab
Process Consequence Measures
• Vital functions are affected • Death
• Blockers of VWF-platelet binding − Anti-VWF aptamers (e.g. ARC1799)
− Nano anti-VWF A1 (e.g. ALX8100)
• Non-suppressible rADAMTS13 variants
• High and/or persistent ADAMTS13
inhibitor levels
• Protracted course
• Death
• Preemptive rituximab?
• Blockers of VWF-platelet binding
• Non-suppressible rADAMTS13 variants
• Iatrogenic complications (e.g. line
sepsis)
• Increased morbidity
• Death • Specialized catheter team
Process Consequence Measures
• Vital functions are affected • Death
• Blockers of VWF-platelet binding − Anti-VWF aptamers (e.g. ARC1799)
− Nano anti-VWF A1 (e.g. ALX8100)
• Non-suppressible rADAMTS13 variants
• Persistent ADAMTS13 inhibitor
levels • Protracted course
• Rituximab
• Blockers of VWF-platelet binding
• Non-suppressible rADAMTS13 variants
Process Consequence Measures
• Vital functions are affected • Death
• Blockers of VWF-platelet binding − Anti-VWF aptamers (e.g. ARC1799)
− Nano anti-VWF A1 (e.g. ALX8100)
• Non-suppressible rADAMTS13 variants
Atypical Presentation of TTP
Time
Mic
rova
scu
lar
thro
mb
osi
s Typical course
Thrombocytopenia
MAHA, Neuro. deficits
Coma
Seizures
Death
ADAMTS13 deficiency
Subclinical thrombosis
TIA/stroke
Normal blood counts
Forme fruste
From Tsai HM, in Enclopedia of Human Biology (in press)
How Should TTP Be Defined?
• Clinical definition:
• Pentad: MAHA, platelet, hematuria, neurological deficits, and fever
• Triad: MAHA, platelet, and neurological deficits
• Diad: MAHA and platelet
– Not specific: These complications may result from other disorders
with different etiology or pathogenesis
– Not inclusive: Some patients of TTP do not present with MAHA
and/or thrombocytopenia
• Pathological definition: microvascular thrombosis
– Microvascular thrombosis may result from different causes
– Thrombosis may be few and not detectable, especially in milder
cases
• Molecular definition
A Molecular Definition of TTP
• ADAMTS13 deficiency, with a propensity to develop microvascular thrombosis
• Autoimmune inhibitors
• Genetic mutations
• Clinical presentation
‒ Active thrombosis: ADAMTS13 <10%
• Conventional TTP
− Thrombocytopenia, MAHA, neurologic complications, and other organ dysfunction
• Chronic thrombosis
− MAHA with mild thrombocytopenia or even thrombocytosis
• Incomplete phenotype
− Thrombocytopenia only (often mistaken to be ITP)
− Neuro. defects without thrombocytopenia or MAHA (often mistaken to be CVA)
− Neuro. defects with thrombocytopenia but no MAHA (often mistaken to be CVA)
‒ No active thrombosis (remission): ADAMTS13 is normal, decreased or <10%
• Patients still have the disease during clinical remission and are prone to develop
thrombosis
TTP without ADAMTS13 Deficiency: Difference in Definition
Authors, year No. Severe def. Excl. renal failure Excl. co-morbidity
Tsai et al, 1998 39 100% Yes (Crmax > 2.5) Yes (overall)
Furlan et al, 1998 24 83% Yes (HUS by referral) No
Veyradier et al, 2001 111 89% Yes (HUS by referral) Yes (by referral)
Bohm et al, 2002 22 91% Not indicated No
Rick et al, 2002 50 78% Not indicated No
Zhou et al, 2004 34 100% Yes (Crmax > 2.5) Yes (overall)
Hovinga et al, 2004 396 57% Yes (HUS by referral) Yes (by referral)
Matsumoto et al, 2004 108 52% Yes (HUS by referral) Yes (by referral)
Coppo et al, 2004 46 67% No Yes (by referral)
Peyvandi et al, 2004 100 48% No No
Terrel et al, 2005 70 31% No Yes (by referral)
Kokame et al, 2005 41 80% Not indicated Not indicated
Authors, year No. Severe def. Excl. renal failure
Tsai et al, 1998 39 100% Yes (Crmax >2.5)
Furlan et al, 1998 24 83% Yes (HUS by referral)
Veyradier et al, 2001 111 89% Yes (HUS by referral)
Bohm et al, 2002 22 91% Not indicated
Rick et al, 2002 50 78% Not indicated
Zhou et al, 2004 34 100% Yes (Crmax >2.5)
Hovinga et al, 2004 396 57% Yes (HUS by referral)
Matsumoto et al, 2004 108 52% Yes (HUS by referral)
Coppo et al, 2004 46 67% No
Peyvandi et al, 2004 100 48% No
Terrel et al, 2005 70 31% No
Kokame et al, 2005 41 80% Not indicated
Authors, year No. Severe def.
Tsai et al, 1998 39 100%
Furlan et al, 1998 24 83%
Veyradier et al, 2001 111 89%
Bohm et al, 2002 22 91%
Rick et al, 2002 50 78%
Zhou et al, 2004 34 100%
Hovinga et al, 2004 396 57%
Matsumoto et al, 2004 108 52%
Coppo et al, 2004 46 67%
Peyvandi et al, 2004 100 48%
Terrel et al, 2005 70 31%
Kokame et al, 2005 41 80%
MAHA: Mechanical Injury of Red Blood Cells
RBC fragmentation
Arteriolar
Stenosis
Abnormal
shear stress
Organ
Ischemia/
dysfunction
Vascular devices
−LVAD
−ECMO
−Prosthetic valves
Thrombocytopenia
Thrombotic
Based on Tsai HM, Am J Med 2013;126:200-209
Pathological Basis of MAHA and Thrombocytopenia
Microvascular
Stenosis/thrombosis
DIC, HELLP CAPS, HIT, PNH
Neoplastic metastasis
Autoimmune dis. Infection
Stx-HUS Pneumo-HUS
aHUS, etc.
Adapted from Tsai HM, in Wintrobe’s Clinical Hematology 13/e (in press)
Tumor cells Fibrin clots
TTP
VWF-platelet
thrombosis
Vasculitis
Thrombocytopenia
Red cell fragmentation
shear stress
Thrombotic
Organ dysfunction
Ischemia
Thrombotic
microangiopathy
ADAMTS13 Activity Segregates TTP from aHUS
Crmax >2.5 mg/dL (Excluding 26 cases of hTTP)
Number and % with TTP
Tsai HM, Hem Onc Clin NA 2013;27:565-584
Atypical HUS (vs. typical, E.coli-HUS)
• Sporadic
• No prodrome of hemorrhagic diarrhea
Regulation of Complement Activation
C4, C2 C4b2a (C3 convertase)
C3
Immune complex + C1qC1r2C1s2 or Microbial mannose + MBL/MASP-1, 2, & 3
C5b C5
C5b-9 (MAC)
C6, C7, C8, C9 C5a
C3a C4b2a3b
(C5 convertase)
Alternative pathway CFP
CFB C3bBb, Ba
(C3 convertase) C3b C3bB CFD
C3bBbC3b (C5 convertase)
C3b
C4a, C2a
MCP
THBD
iC3b
CFI CFH
iC5a
iC3a
CPB2a CPB2 Thrombin/
THBD
Cla
ssic
/le
ctin
pat
hw
ay
Tsai HM, Hem Onc Clin NA 2013;27:565-584
CD55
CD59
Genetics of aHUS
Based on
Noris et al, CJASN 2010; 5:1844
Fremeaux-Bacchi et al, CJASN 2013;8:554
Vertical bar = 95% CI
American, N=144
French, N=200
Maga CH et al, Hum Mutat 2010;31:E1445
Italian, N=260
Defective regulation of the alternative complement pathway
Uncontrolled complement activation
Organ dysfunction Ischemia Thrombosis
Thrombocytopenia RBC fragmentation
Shear Stress Stenosis
Stenosis Ischemia
Endothelial injury
C5b-9 (MAC)
C3a, C5a
Vascular permeability
Histamine
release
Tissue edema
Effusions
Pathophysiology of aHUS
Endothelial swelling
Subendothelial expansion
Tsai HM, Hem Onc Clin NA 2013;27:565-584
TTP and aHUS: Different Pathology
aHUS
TTP
Based on Tsai HM, Am J Med 2013;126:200-209
Kidney Kidney Kidney Kidney
Silver stain
Heart Kidney Brain Brain
aHUS: Common Findings at Autopsy
Interstitial edema
Brain
Lung
Heart
Pancreas
Gastrointestinal tract
Mesentery
Skin
Thrombotic
microangiopathy
Kidney
Uncommon in other organs
Cavitary fluids
Pleural effusion
Pericardial effusion
Ascites
Posterior Reversible Encephalopathy Syndrome (PRES)
T2-weighted FLAIR
Purtscher's-like Retinopathy
Clinical Features of aHUS
• Age: Children Adults
• Gender: Female Male
• A systemic disease affecting multiple organs
– Kidney: acute and chronic renal failure
– Hypertension
– CNS: headache, mental change, seizure, retinopathy, focal deficit
– Digestive: abdominal pain, N/V, diarrhea, pancreatitis, DM
– Lung: chest pain, dyspnea, airway wall thickening, pleural effusions,
pulmonary infiltrates, ARDS
– C-V: chest pain, myocardial injury, arrhythmia, CHF, pericardial effusion
– Liver: abnormal liver functions
• Laboratory correlation
– Organ dysfunction does not always correlate with thrombocytopenia
and/or MAHA
Laboratory Diagnosis of aHUS
• Conventional complement tests: C3, C4, CH50, AH50
– Abnormal in 30%
– Not specific for aHUS
• Plasma CFH and CFI protein concentrations
− Decreased in 30% of patients with CFH or CFI mutations
• Mutation analysis (CFH, MCP, CFI, CFB, C3, THBD)
– Abnormal in 40% (sporadic) - 70% (familial)
• CFH antibody
– 5% - 10%
• Skin biopsy?
− Immunodetection of complement activation products
• Measurement of sMAC?
− Technically unreliable
aHUS: Molecular Defects is A Major Determinant of Prognosis
Event: relapse, death or ESRD
Eve
nt
free
su
rviv
al,
%
Time, months
CFH antibodies
MCP
C3
THBD
CFH
No mutations
CFI
Noris M et al, CJASN 2010;5:1844
0 10 20 30 40 50 60 70 80 900
100
200
300
400
PEx
Abd. pain vision
Days after admission
Pla
tele
ts/L
(10
-9)
aHUS: Unpredictable Responses to Plasma Exchange
Death
0 10 20 30 40 50 60 70 80 900
2
4
6
8
10 HD
Days after admission
Cre
ati
nin
e,
mg
/dL
0 10 20 30 40 50 60 70 80 900
2
4
6
8
Days after admission
LD
H (
x10
3),
U/m
LUnconscious
Lessons
• The response to plasma therapy is unpredictable in aHUS
− Response, followed by lack of response
− Response and resolution
− Response, requiring maintenance
− No or partial response
• Improvement in CBC is not always indicative of disease
resolution in aHUS
Eculizumab Replaces Plasma Exchange for Active aHUS
Legendre CM et al, NEJM 2013;368:2169
Active disease, N = 17
Eculizumab Replaces Maintenance Plasma Therapy for aHUS
Legendre CM et al, NEJM 2013;368:2169
Plasma maintenance , N = 20
MAHA with Comorbidity
Crmax >2.5 mg/dL (Excluding 26 cases of hTTP)
Tsai HM, Hem Onc Clin NA 2013;27:565
• HIV infection
• HSCT
• Neoplastic dis.
• Lupus, etc.
Number and % with TTP
Roles of Co-Morbidity in MAHA and Thrombocytopenia
Mechanism Examples
I: Idiopathic
• VWF-platelet aggregation
• Endothelial injury by complement activation
• Endothelial injury by DAGKE mutations
• TTP: ADAMTS13 deficiency: Inhibitors or genetic mutations
• aHUS: Defective complement regulation, genetic or auto-Ab
• DAGKE deficiency (aHUS?)
II: Triggers in patients with pre-existing TTP or aHUS
• TTP:
− ↑VWF secretion, shear stress, ADAMTS13 inhibitors
− ↓ADAMTS13 activity
• Complement activation in aHUS
• Infection, surgery, trauma, pregnancy, IV contrast, hemodialysis
III: Inducers of TTP or aHUS
• ADAMTS13 inhibitors
• Auto-Ab (e.g. CFH antibodies)
• Ticlopidine-TTP; HSCT-TTP, HIV? CTD?
• HSCT-HUS, HIV-HUS? CTD-HUS?
IV: TMA (endothelial injury) via other mechanisms
• Direct toxin cytotoxicity
• Natural Ab binding to T-Ag
• Deprivation of angiogenesis signals
• Malignant hypertension
• Others
• Shiga toxins of E. coli O157:H7 in typical HUS
• Microbial neuraminidase of S. pneumoniae sepsis
• Excessive sVEGFR2/sFlt1 of preeclampsia, anti-VEGF (bevacizumab)
• (A consequence of aHUS)
• (Various drugs?)
V: Other types of pathology
• Fibrin thrombosis
• Vasculitis
• Intravascular tumor cells
• Vascular devices
• DIC, CAPS, HIT, HELLP syndrome of pregnacy, PNH
• Lupus vasculitis, scleroderma crisis, Rocky Mountain spotted fever, anthrax
• Metastatic diseases
• VAD, ECMO, prosthetic heart valves
Mechanism Examples
I: Idiopathic
• VWF-platelet aggregation
• Endothelial injury by complement activation
• Endothelial injury by DAGKE mutations
• TTP: ADAMTS13 deficiency: Inhibitors or genetic mutations
• aHUS: Defective complement regulation, genetic or auto-Ab
• DAGKE deficiency (aHUS?)
II: Triggers in patients with pre-existing TTP or aHUS
• TTP:
− ↑VWF secretion, shear stress, ADAMTS13 inhibitors
− ↓ADAMTS13 activity
• Complement activation in aHUS
• Infection, surgery, trauma, pregnancy, IV contrast, hemodialysis
III: Inducers of TTP or aHUS
• ADAMTS13 inhibitors
• Auto-Ab (e.g. CFH antibodies)
• Ticlopidine-TTP; HSCT-TTP, HIV? CTD?
• HSCT-HUS, HIV-HUS? CTD-HUS?
IV: TMA (endothelial injury) via other mechanisms
• Direct toxin cytotoxicity
• Natural Ab binding to T-Ag
• Deprivation of angiogenesis signals
• Endothelial injury?
• Others
• Shiga toxins of E. coli O157:H7 in typical HUS
• Microbial neuraminidase of S. pneumoniae sepsis
• Excessive sVEGFR2/sFlt1 of preeclampsia, anti-VEGF (bevacizumab)
• CNI inhibitors, malignant hypertension (may be a consequence of aHUS)
• Gemcitabine, cocaine, etc.
Mechanism Examples
I: Idiopathic
• VWF-platelet aggregation
• Endothelial injury by complement activation
• Endothelial injury by DAGKE mutations
• TTP: ADAMTS13 deficiency: Inhibitors or genetic mutations
• aHUS: Defective complement regulation, genetic or auto-Ab
• DAGKE deficiency (aHUS?)
II: Triggers in patients with pre-existing TTP or aHUS
• TTP:
− ↑VWF secretion, shear stress, ADAMTS13 inhibitors
− ↓ADAMTS13 activity
• Complement activation in aHUS
• Infection, surgery, trauma, pregnancy, IV contrast, hemodialysis
III: Inducers of TTP or aHUS
• ADAMTS13 inhibitors
• Auto-Ab (e.g. CFH antibodies)
• Ticlopidine-TTP; HSCT-TTP; HIV? CTD?
• HSCT-HUS; HIV-HUS? CTD-HUS?
Mechanism Examples
I: Idiopathic
• VWF-platelet aggregation
• Endothelial injury by complement activation
• Endothelial injury by DAGKE mutations
• TTP: ADAMTS13 deficiency: Inhibitors or genetic mutations
• aHUS: Defective complement regulation, genetic or auto-Ab
• DAGKE deficiency (aHUS?)
II: Triggers in patients with pre-existing TTP or aHUS
• TTP:
− ↑VWF secretion, shear stress, ADAMTS13 inhibitors
− ↓ADAMTS13 activity
• Complement activation in aHUS
• Infection, surgery, trauma, pregnancy, IV contrast, hemodialysis
Mechanism Examples
I: Idiopathic
• VWF-platelet aggregation
• Endothelial injury by unregulated complement activation
• EC injury by excessive AA-diacyglycerol
• TTP: ADAMTS13 deficiency: Inhibitors or genetic mutations
• aHUS: Defective complement regulation, genetic or auto-Ab
• TMA due to DAGKE mutations (aHUS?)
Atypical HUS after Autologous HSCT
54 year-old female
• Three months after auto-HSCT for myeloma
• Day -9:
– Abdominal pain, vomiting, diarrhea – Mild thromobocytopenia, anemia & azotemia
– Stool: C. difficile + – Tx: metronidazole
• Day -7:
– Seizures, anuric
– Platelet 25x109/L, MAHA
– Thalidomide, acyclovir were discontinued
– PEx for ‘TTP’; HD for ARF
• Day -1: DMS, vomiting, intubated
• Labs at transfer: – Hb 85 g/L, platelet 99x109/L, , LDH 1,271 U/L
– Cr 4.0 mg/dL
– Smear: schistocytes
– ANA, shiga toxin assay, viral cultures: negative
– (ADAMTS13: 60%)
0 20 40 60 80 100
50
100
150
200PEx
Eculizumab
Discharge
Days from admission
Pla
tele
ts/L
(x10
-9)
Slow Recovery of Renal Function during Eculizumab Therapy
0 200 400 600 8000
2
4
6
8
0
20
40
60
80Hemodialysis
Cr
CCr
Eculizumab
Days from admission
Cr,
mg
/dL
CC
r , mL
/min
/1.7
3 m
2
0 200 400 600 8000
50
100
150
200
250
0
100
200
300
400EculizumabPEx
RituximabPlatelet count
CFH Ab
Days from admission
Pla
tele
ts/L
(10
-9) C
FH
Ab
(U/m
L)
Tsai HM, Hem Onc Clin NA 2013;27:565-584
Lessons
• Atypical HUS with anti-CFH may occur after HSCT
‒ Deranged regulation of autoimmunity during post-myeloablation
recovery of the immune system
• Anti-complement therapy may be effective for aHUS after
HSCT
• The recovery of renal function may occur over many months.
• Do not give up hope prematurely and rush the patient to renal
transplantation.
Difference between TTP and aHUS
Disease TTP aHUS
Molecular pathogenesis
• ADAMTS13-inhibitory autoantibodies • Genetic mutations, <5%
• Defective complement regulation Genetic defects Auto-Ab of CFH, 5%-10%
Pathology • Arteriolar and capillary thrombosis comprising VWF and platelets
•Thrombotic microangiopathy Endothelial injury, sub-endothelial widening Thrombosis Abnormal vascular permeability
Mechanisms of organ dysfunction
• Thrombotic ischemia •Thrombotic ischemia • Non-thrombotic ischemia • Interstitial edema
Clinical • Thrombocytopenia precedes MAHA and organ dysfunction • CNS: focal deficits, mental changes, seizures, coma • Cardiac: arrhythmia, heart failure
• Organ dysfunction does not always correlate with thrombocytopenia or MAHA • Renal failure • Hypertension • Tissue edema, fluid accumulation
Diagnosis • ADAMTS13 activity assays • Exclusion of TTP • Exclusion of other TMA or pathology • Clinical features • Laboratory dx: problematic
Treatment • Plasma exchange or infusion • Rituximab immunosuppression • Future: rADAMTS13 proteins Blockers of VWF-platelet binding
• Anti-complement therapy with eculizumab (anti-C5) •Plasma exchange or infusion only when eculizumab is not available • Soluble r-thrombomodulin?
Disease TTP aHUS
Molecular pathogenesis
• ADAMTS13-inhibitory autoantibodies • Genetic mutations, <5%
• Defective complement regulation Genetic defects Auto-Ab of CFH, 5%-10%
Pathology • Arteriolar and capillary thrombosis comprising VWF and platelets
•Thrombotic microangiopathy Endothelial injury, sub-endothelial widening Thrombosis Abnormal vascular permeability
Mechanisms of organ dysfunction
• Thrombotic ischemia •Thrombotic ischemia • Non-thrombotic ischemia • Interstitial edema
Clinical • Thrombocytopenia precedes MAHA and organ dysfunction • CNS: focal deficits, mental changes, seizures, coma • Cardiac: arrhythmia, heart failure
• Organ dysfunction does not always correlate with thrombocytopenia or MAHA • Renal failure • Hypertension • Tissue edema, fluid accumulation
Diagnosis • ADAMTS13 activity assays • Exclusion of TTP by ADAMTS13 assays • Exclusion of other TMA or pathology • Clinical features • Laboratory dx: helpful but problematic
Disease TTP aHUS
Molecular pathogenesis
• ADAMTS13-inhibitory autoantibodies • Genetic mutations, <5%
• Defective complement regulation Genetic defects Auto-Ab of CFH, 5%-10%
Pathology • Arteriolar and capillary thrombosis comprising VWF and platelets
•Thrombotic microangiopathy Endothelial injury, sub-endothelial widening Thrombosis Abnormal vascular permeability
Mechanisms of organ dysfunction
• Thrombotic ischemia •Thrombotic ischemia • Non-thrombotic ischemia • Interstitial edema
Clinical • Thrombocytopenia precedes MAHA and organ dysfunction • CNS: focal deficits, mental changes, seizures, coma • Cardiac: arrhythmia, heart failure
• Organ dysfunction does not always correlate with thrombocytopenia or MAHA • Renal failure • Hypertension • Tissue edema, fluid accumulation
Disease TTP aHUS
Molecular pathogenesis
• ADAMTS13-inhibitory autoantibodies • Genetic mutations, <5%
• Defective complement regulation Genetic defects Auto-Ab of CFH, 5%-10%
Pathology • Arteriolar and capillary thrombosis comprising VWF and platelets
•Thrombotic microangiopathy Endothelial injury, sub-endothelial widening Thrombosis Abnormal vascular permeability
Mechanisms of organ dysfunction
• Thrombotic ischemia •Thrombotic ischemia • Non-thrombotic ischemia • Interstitial edema
Disease TTP aHUS
Molecular pathogenesis
• ADAMTS13-inhibitory autoantibodies • Genetic mutations, <5%
• Defective complement regulation Genetic defects Auto-Ab of CFH, 5%-10%
Pathology • Arteriolar and capillary thrombosis comprising VWF and platelets
•Thrombotic microangiopathy (TMA) Endothelial injury, sub-endothelial widening Thrombosis Abnormal vascular permeability
Disease TTP aHUS
Molecular pathogenesis
• ADAMTS13-inhibitory autoantibodies • Genetic mutations, <5%
• Defective complement regulation Genetic defects Auto-Ab of CFH, 5%-10%
Summary
• Microangiopathic hemolysis is a consequence of red cell injury by
mechanical force.
• In patients without vascular devices, MAHA signifies one of the
following pathological conditions
– Arteriolar VWF-platelet thrombosis of TTP
– Fibrin thrombosis of DIC, HELLP syndrome, or less commonly heparin
induced thrombocytopenia, catastrophic antiphospholipid syndrome, or
paroxysmal nocturnal hemoglobinuria
– Intravascular cancer cells
– Vasculitis, or
– Thrombotic microangiopathy of shiga toxin-HUS, HUS in association with
pneumococcal sepsis, defective complement regulation of the alternative
complement system, (aHUS) or mutations of diacylglycerol kinase epsilon
(DAGKE)
Common Misuse of Diagnostic Terms
• MAHA and thrombocytopenia TTP
• MAHA and thrombocytopenia TMA
• MAHA and thrombocytopenia without ADAMTS13 deficiency TMA
• TTP without ADAMTS13: A term that defies definition
• TTP/HUS: A term that defies definition