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Anti-Phospholipase A2 Receptor Antibody - Clinical Application for Membranous Nephropathy - Dr. Gawad
1. Anti-Phospholipase A2
Receptor Antibody
Clinical Application for
Membranous Nephropathy
Mohammed Abdel Gawad
Nephrology Specialist
Kidney & Urology Center (KUC)
Alexandria – EGY
drgawad@gmail.com
Mansoura MD Program – 12 / Jan / 2017
2. Steps of Management of MN
Evaluation
of secondary causes
Therapy:
Secondary: Treat the cause
Idiopathic: Specific
Treatment
Kidney Int Suppl. 2012;2:139-274
3. Subepithelial deposits MN
Possible Mechanisms
Glassock RJ. N Engl J Med 2009;361:81-83.
Possible Mechanisms of the Formation of Subepithelial Deposits in Experimental Models of, and Patients with,
Membranous Nephropathy.
1ry MN2ry MN 2ry MN
7. N terminal cysteine rich domain
Fibronectin type II domain
Transmembrane domain
Short intracellular C terminal tail
C type lectin like domains
J Am Soc Nephrol. 2015 Feb;26(2)
N Engl J Med. 2009 Jul 2;361(1)
A major epitope that is recognized
by 90% of human anti-PLA2R
autoantibodies
13. Anti-PLA2R antibodies have been identified in
57, 74, 75, 78, 80, and 82 percent of patients
with primary membranous nephropathy
J Am Soc Nephrol. 2015 Oct;26(10)
Kidney Int. 2013;83(5)
J Am Soc Nephrol. 2012 Oct;23(10)
Clin J Am Soc Nephrol. 2011;6(6)
J Am Soc Nephrol. 2011;22(6)
N Engl J Med. 2011;364(7):689
17. • PLA2R has been detected in the immune
deposits of some patients with secondary MN
due to:
–HCV, HBV
–Neoplasms
–Sarcoidosis
–Other inflammatory & autoimmune
diseases
Am J Nephrol. 2015 ; 41(4-5)
Medicine (Baltimore). 2015 ; 94(30)
18. Secondary MN with positive anti-PLA2R,
how?
Associated conditions may represent a disease-
precipitating “second hit” in a patient
genetically and immunologically predisposed to
develop MN
Anti-PLA2R
Is it only related to Idiopathic MN?
Am J Kidney Dis. 2016 Jul;68(1)
19. Any patient with nephrotic syndrome
who tests positive for anti-PLA2R
is almost certain to have MN
20. Talk Outline
• Molecular character
• anti-PLA2R autoantibodies
– Diagnosis:
• Primary vs Secondary
• Immunoassays used for diagnosis
– Correlation with:
• Disease presentation:
– Proteinuria and disease severity
– Progression of renal failure
• Remission:
– Spontaneous
– Remission after therapy:
» Immunosuppression
» Rituximab
• Relapse
• Post kidney transplantation recurrence
• Glomerular PLA2R antigen detection
• A proposal for serology based approach
29. Indian J Nephrol. 2016 Jul-Aug;26(4)
Association of serum anti-PLA2R
antibodies with proteinuria
30. n = 118
The clinical end point:
increase of serum
creatinine by ≥ 25% and
serum creatinine reaching
≥ 1.3 mg/dl
anti-PLA2R antibody titer
measured within 6 months
of kidney biopsy and prior
to any immunosuppressive
therapy
Clin J Am Soc Nephrol. 2014 Nov 7;9(11)
31. Talk Outline
• Molecular character
• anti-PLA2R autoantibodies
– Diagnosis:
• Primary vs Secondary
• Immunoassays used for diagnosis
– Correlation with:
• Disease presentation:
– Proteinuria and disease severity
– Progression of renal failure
• Remission:
– Spontaneous
– Remission after therapy:
» Immunosuppression
» Rituximab
• Relapse
• Post kidney transplantation recurrence
• Glomerular PLA2R antigen detection
• A proposal for serology based approach
45. Transplantation. 2015 Aug;99(8)
anti-PLA2R levels (cut-off of 45 U/mL) during the
pretransplantation period accurately predicted
pMN recurrence, with a sensitivity of 85.3%,
specificity of 85.1%
47. • Other factors that may affect post Tx recurrence:
– anti-PLA2R antibody titer
– Donor and recipient relatedness, class II major
histocompatibility complex interactions
– Potency of transplant immunosuppression
therapy
Transplantation. 2015;99(8)
Nephrol Dial Transplant. 2014;29(12)
Am J Transplant. 2012;12(1)
Probability of recurrence of MN after kidney Tx
is not only affected by anti-PLA2R antibody
seropositivity level at the time of
transplantation
48. Recurrence of MN after kidney Tx despite a
negative pre-transplantation test result for anti-
PLA2R antibodies
Am J Kidney Dis. 2016 Jul;68(1)
Transplantation. 2013;95(10)
Cause Post-transplantation
anti-PLA2R ab
awakening of memory cells Positive
anti-THSD7A antibodies Negative
De Novo MN Negative
49. Talk Outline
• Molecular character
• anti-PLA2R autoantibodies
– Diagnosis:
• Primary vs Secondary
• Immunoassays used for diagnosis
– Correlation with:
• Disease presentation:
– Proteinuria and disease severity
– Progression of renal failure
• Remission:
– Spontaneous
– Remission after therapy:
» Immunosuppression
» Rituximab
• Relapse
• Post kidney transplantation recurrence
• Glomerular PLA2R antigen detection
• A proposal for serology based approach
58. Kidney Int. 2016 Jun;89(6):1399
This does not support the hypothesis that
antibodies could only be detected once the buffer
capacity of the kidney is exceeded
59. PLA2R deposit in kidney
Is it only related to Idiopathic MN?
Nephrol Dial Transplant. 2013 Jul;28(7)
60. PLA2R deposit in kidney
Is it only related to Idiopathic MN?
J Am Soc Nephrol. 2011;22(6)
Also a few patients with secondary MN to lupus
and cancer have positive PLA2R immunostaining
in kidney biopsy
61. Secondary MN with positive PLA2R in
kidney biopsy, how?
Associated conditions may represent a disease-
precipitating “second hit” in a patient
genetically and immunologically predisposed to
develop MN
PLA2R deposit in kidney
Is it only related to Idiopathic MN?
Am J Kidney Dis. 2016 Jul;68(1)
62. Talk Outline
• Molecular character
• anti-PLA2R autoantibodies
– Diagnosis:
• Primary vs Secondary
• Immunoassays used for diagnosis
– Correlation with:
• Disease presentation:
– Proteinuria and disease severity
– Progression of renal failure
• Remission:
– Spontaneous
– Remission after therapy:
» Immunosuppression
» Rituximab
• Relapse
• Post kidney transplantation recurrence
• Glomerular PLA2R antigen detection
• A proposal for serology based approach
This is important in patients for whom kidney biopsy poses a high risk, such as those needing anticoagulation for thromboembolic disease and patients with a single kidney.
Western blotting, which is both sensitive and very specific for the detection of anti- PLA2R when recombinant human PLA2R is used as the antigen. However, the technique is costly, labor intensive, and impractical for routine clinical use.
compared with the Western blot assay for anti-PLA2R, the commercial IIFA and ELISA tests are highly specific for primary MN versus secondary MN and other forms of glomerular disease, although the ELISA is somewhat less sensitive using the recommended cutoff for positivity.
Although the IIFA is relatively high throughput, anti-PLA2R titers are semiquantitative and observer dependent, and reactivity with other baseline cell antigens may occasionally predispose to equivocal results. It is generally used as an initial screening assay, much like antineutrophil cytoplasmic antibody assays, before proceeding to the highthroughput and more quantitative and specific ELISA.
Control:
50 normal healthy controls,
41 nephrotic disease controls (patients presenting with nephrotic syndrome in which biopsy revealed underlying cause different from IMN
Control:
50 normal healthy controls,
41 nephrotic disease controls (patients presenting with nephrotic syndrome in which biopsy revealed underlying cause different from IMN
Control:
50 normal healthy controls,
41 nephrotic disease controls (patients presenting with nephrotic syndrome in which biopsy revealed underlying cause different from IMN
PLA2R antibody levels associated with clinical disease activity (proteinuria) in
patients with immunosuppressive therapy (n=101) or supportive care (n=32).
Serum levels of PLA2R-Ab were first measured by an indirect immunofluorescence test (8,13). After development of an ELISA (14) by EUROIMMUN AG, we continued measurements of total IgG and IgG4 subclass PLA2R-Ab by ELISA.
the ELISA results were considered positive at a level .20 units/ml for IgG PLA2R-Ab and .0.259 units/ml for IgG4 PLA2R-Ab.
Within 3 months after the start of the immunosuppressive therapy (0 months), proteinuria decreases by 39% and PLA2R antibody levels by 81%. Proteinuria continuously declines during the further follow-up, whereas PLA2R antibody levels remained low.
*P < 0.05, statistically significant difference between the single time point and the start of immunosuppression (0 months
higher anti-PLA2R titers within two years of diagnosis predicted substantially greater progression of kidney function decline over the subsequent five years of follow-up
De Novo:
most likely the result of alloantibodies in the transplant rather than the autoantibodies responsible for recurrent primary MN.
associated with evidence of antibody-mediated rejection and circulating donor specific antibodies.80-82
Whereas IgG4 is usually the dominant or codominant IgG subclass deposited in recurrent MN, the IgG1 subclass predominates in de novo MN.83
Assays for circulating anti-PLA2R antibodies or staining for PLA2R on kidney biopsy specimens almost always gives negative results in patients with de novo MN.84
PLA2R positivity is an ideal tool for differentiating between recurrent and de novo MN in patients in whom the original cause of ESRD was unknown.
a minority of patients who are seropositive for anti-PLA2R antibodies exhibit no staining for PLA2R within the immune deposits of their corresponding biopsy specimens. This may represent masking by autoantibodies of epitopes recognized by the commercial antibody used for IF staining, but has not yet been fully explored.
a minority of patients who are seropositive for anti-PLA2R antibodies exhibit no staining for PLA2R within the immune deposits of their corresponding biopsy specimens. This may represent masking by autoantibodies of epitopes recognized by the commercial antibody used for IF staining, but has not yet been fully explored.