The association of serum anti-PLA2R antibody and glomerular PLA2R antigen staining with clinical manifestations and outcomes in membranous nephropathy.

BACKGROUND: Phospholipase A2 receptor (PLA2R)-associated membranous nephropathy (MN) was manifested as seropositive for PLA2R antibodies (SAb) and/or glomerular PLA2R antigens' (GAg) deposits. According to the test of SAb and GAg, PLA2R-associated MN can be divided into SAb + /GAg-, SAb-/GAg + , and SAb + /GAg + groups. The clinical characteristics and outcomes of the three groups need to be further evaluated. METHODS: 184 PLA2R-associated MN patients were enrolled. SAb was measured by enzyme-linked immunosorbent assay with a cut-off value of 14 RU/mL. GAg was detected by immunofluorescence using a paraffin section of renal biopsy samples. Clinical characteristics and the decline of eGFR were compared among the 3 groups. RESULTS: There were 33 SAb + /GAg-, 46 SAb-/GAg +, and 105 SAb + /GAg + PLA2R-associated MN patients reviewed. Clinical characteristics, such as the level of proteinuria, serum albumin, as well as eGFR, were comparable between the SAb + /GAg- and SAb + /GAg + patients. While SAb-/GAg + patients exhibited mild clinical manifestations as evidenced by higher serum albumin (P < 0.001) and lower proteinuria (p = 0.049) compared with SAb + /GAg + patients. After 21.96 ± 7.39 month follow-up, the eGFR decrease was no difference between the SAb + /GAg- and SAb + /GAg + patients. SAb-/GAg + patients had a lower rate of the > 20% eGFR decline as well as a 50% eGFR decline compared with the SAb + /GAg + patients (10.87% vs 30.48%, p = 0.013; 0.00% vs 4.76%, p = 0.324). CONCLUSIONS: Our study showed that the clinical manifestations of SAb + /Gag- patients were the same as those of double-positive patients, while SAb-/GAg + patients exhibited mild clinical manifestations and slower eGFR decline compared to the double-positive patients.

Characteristics of patients with coexisting IgA nephropathy and membranous nephropathy.

BACKGROUND: Coexistence of IgA nephropathy (IgAN) and membranous nephropathy (MN) in the same patient is rare. Few studies have reported the clinical and pathological features of patients with combined IgAN and MN (IgAN-MN). METHODS: The clinico-pathological features, levels of galactose-deficient IgA1 (Gd-IgA1) and autoantibodies against M-type transmembrane phospholipase A2 receptor (anti-PLA2R) in sera were compared among IgAN-MN, IgAN, and MN patients. RESULTS: Twenty-six patients with biopsy-proven IgAN-MN were enrolled. The mean age at biopsy was 43.6 ± 15.9 years, and 65.4% were male. Proteinuria and estimated glomerular filtration rate (eGFR) levels in patients with IgAN-MN were similar to that of MN patients. Compared with the IgAN patients, IgAN-MN patients showed a higher median proteinuria level (4.3 vs. 1.2 g/day, p < .001), and a higher mean eGFR level (101.8 ± 25.4 vs. 78.6 ± 26.9 mL/min/1.73 m2, p < .001). IgAN-MN patients presented with milder pathological lesions than IgAN patients according to the Oxford Classification. IgAN-MN patients had comparable serum levels of Gd-IgA1 with those of IgAN patients (353.4 ± 95.5 vs. 347.0 ± 109.6 U/mL, p = .801). Percentage of IgAN-MN patients with detectable serum levels of anti-PLA2R was lower than that of MN patients (38.5% vs. 68.6%, p = .011). CONCLUSIONS: IgAN-MN patients display similar clinical features to MN patients and milder pathological lesions than IgAN patients. IgAN-MN patients have similar levels of Gd-IgA1 to those of IgAN patients, and a lower proportion of anti-PLA2R than MN patients.

Clinical features of IgA nephropathy with serum ANCA positivity: a retrospective case-control study.

BACKGROUND: The coexistence of IgA nephropathy (IgAN) and antineutrophil cytoplasmic autoantibodies (ANCAs) is relatively rare. Only a few studies have reported the features of these patients. METHODS: We studied the clinical and histological features of 20 ANCA-positive IgAN patients. They were compared with ANCA-negative IgAN patients (n = 40) and ANCA-associated systemic vasculitis (AASV) patients (n = 40) with a randomly selected and matched proportion of crescentic glomeruli. Furthermore, 9 ANCA-positive crescentic IgAN patients out of the 20 cases were compared with two control groups with crescentic nephritis. RESULTS: ANCA-positive IgAN patients showed older age, lower haemoglobin and higher inflammatory indicator levels at baseline, and a higher percentage of general symptoms and pulmonary involvement, compared with ANCA-negative IgAN patients, and were comparable to AASV patients. Histologically, there was a significantly higher percentage of fibrinoid necrosis in glomeruli in ANCA-positive IgAN patients and in AASV patients compared with ANCA-negative IgAN patients (35, 25 and 0%, respectively, P = 0.003). After immunosuppressive therapy, ANCA-positive crescentic IgAN patients were more likely to withdraw from dialysis (75 versus 9.1%, P = 0.03) and not to reach end-stage renal disease within 6 months (11.1 versus 66.7%, P = 0.01) compared with ANCA-negative crescentic IgAN patients. CONCLUSIONS: IgAN patients with ANCA positivity showed more severe clinical and histological features when compared with ANCA-negative IgAN patients and were comparable to AASV patients. However, renal prognosis was relatively better in ANCA-positive crescentic IgAN patients after aggressive immunosuppressive therapy in the short term, compared with ANCA-negative patients.