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Determination of Anti-Phospholipase A2 and Anti-Thrombospondin Type 1 Domain-Containing Protein 7A in Latin Patients
Ligia C Battaini1, Otavio T Ranzani2,3, Lia J Marçal4
1Nephrology Division, University of Sao Paulo, Sao Paulo 04458-020, Brazil.
Abstract:
Primary membranous nephropathy (MN) is caused by antibodies against podocyte antigens, especially the type M receptor of phospholipase A2 (PLA2R) and thrombospondin type-1 domain containing 7 A (THSD7A). This study's aim was the determination of anti-PLA2R, anti-THSD7A serum antibodies, and anti-PLA2R renal tissue staining prevalence in a Latin population with MN, as well as evaluating their role as biomarkers for disease activity. The performance of the two anti-PLA2R serum diagnostic methods-ELISA and indirect immunofluorescence (IFI)-was evaluated for the diagnosis of MN. Fifty-nine patients, including 29 with MN, 18 with lupus membranous nephropathy (LMN) and 12 with focal and segmental glomerulosclerosis (FSGS), were evaluated for serum antibodies. Renal biopsies were also evaluated for the presence of anti-PLA2R staining. Twenty-one patients with MN were followed for 1 year. Patients with LMN and FSGS were negative for both antibodies. All 29 MN patients were negative for anti-THSD7A; 16 MN patients were positive for anti-PLA2R by ELISA and/or IFI, and 3 MN patients were positive for anti-PLA2R only by IFI. Thus, the anti-PLA2R ELISA test demonstrated 45% sensitivity and 97% specificity, while the IFI test showed, respectively, 55% and 100% in our MN patients. Among the 28 MN renal biopsies, 20 presented anti-PLA2R positive staining, corresponding to a 72% sensitivity. Positive correlations were observed between the anti-PLA2R ELISA titer and proteinuria. In conclusion, determination of anti-PLA2R antibodies in the MN Latin population showed similar rates to those reported for other populations. The anti-PLA2R serum levels correlated with MN disease activity.
Insights
This study found that anti-phospholipase A2 receptor (anti-PLA2R) antibodies are prevalent in Latin patients with primary membranous nephropathy (MN). Anti-PLA2R serum levels correlate with MN disease activity, serving as a biomarker.
Area of Science:
- Nephrology
- Immunology
- Pathology
Background:
- Primary membranous nephropathy (MN) is an autoimmune kidney disease.
- Antibodies against podocyte antigens, particularly phospholipase A2 receptor (PLA2R), are key drivers of MN.
- Understanding the prevalence and diagnostic utility of anti-PLA2R antibodies in diverse populations is crucial.
Purpose of the Study:
- To determine the prevalence of anti-PLA2R and anti-THSD7A serum antibodies in a Latin population with MN.
- To assess the diagnostic performance of ELISA and indirect immunofluorescence (IFI) for anti-PLA2R antibodies.
- To evaluate the role of anti-PLA2R antibodies as biomarkers for MN disease activity.
Main Methods:
- Serum samples and renal biopsies from patients with MN, lupus membranous nephropathy (LMN), and focal and segmental glomerulosclerosis (FSGS) were analyzed.
- Detection of anti-PLA2R and anti-THSD7A antibodies was performed using ELISA and IFI.
- Anti-PLA2R staining in renal tissue was assessed via immunofluorescence.
- Correlation between anti-PLA2R antibody titers and proteinuria was examined.
Main Results:
- Anti-THSD7A antibodies were not detected in any MN patients.
- Anti-PLA2R antibodies were detected in 16 out of 29 MN patients by ELISA and/or IFI.
- IFI demonstrated higher sensitivity (55%) than ELISA (45%) for detecting anti-PLA2R antibodies in serum.
- Renal biopsy staining for anti-PLA2R showed 72% sensitivity.
- A positive correlation was observed between anti-PLA2R ELISA titers and proteinuria levels.
Conclusions:
- Anti-PLA2R antibodies are a significant factor in primary MN within the Latin population.
- Both ELISA and IFI are valuable tools for diagnosing MN, with IFI showing higher sensitivity.
- Anti-PLA2R antibody levels serve as reliable biomarkers for monitoring MN disease activity and correlating with proteinuria.
