The relationship between glomerular IgG staining and poor prognostic findings in patients with IgA nephropathy: the data from TSN-GOLD working group

Abstract

Background Galactose-deficient IgA1 (Gd-IgA1) has an increased tendency to form immunocomplexes with IgG in the serum, contributing to IgAN pathogenesis by accumulating in the glomerular mesangium. Several studies showed that glomerular IgG deposition in IgAN is an important cause of mesangial proliferation and glomerular damage. This study aims to determine the association of the positivity of IgG and the intensity of IgG staining with a poor renal prognosis. Methods A total of 943 IgAN patients were included in the study. Glomerular IgG staining negative and positive patients were compared using Oxford classification scores, histopathological evaluations, proteinuria, eGFR, albumin, blood pressures. IgG positive patients were classified as (+), (++), (+++) based on their staining intensity, and the association with the prognostic criteria was also evaluated. Results 81% (n = 764) of the patients were detected as IgG negative, while 19% (n = 179) were positive. Age, gender, body mass index, blood pressure, proteinuria, eGFR, uric acid values were similar in IgG positive and negative patients who underwent biopsy (p > 0.05). Intensity of glomerular IgG positivity was not found to be associated with diastolic and systolic blood pressure, urea, uric acid, age, eGFR, albumin, proteinuria (p > 0.05 for all, r = − 0.084, r = − 0.102, r = − 0.006, r = 0.062, r = 0.014, r = − 0.044, r = − 0.061, r = − 0.066, r = 0.150, respectively). There was no difference for histopathological findings between IgG (+), IgG (++), IgG (+++) groups (for all, p > 0.05). Conclusion Glomerular IgG negativity and positivity detected by routine IFM in IgAN patients is not associated with poor renal prognostic risk factors.

Glomerular IgG deposition predicts kidney disease progression in IgA nephropathy

“…Some researchers have investigated whether the intensity of IgG staining could have an impact on the kidney outcomes in IgAN. In one study, no correlation was found between the intensity of IgG staining and various clinical parameters and Oxford scores in IgAN [ 20 ]. A Japanese cohort study reported an opposite conclusion that the intensity of IgG in the capillary loops was associated with a decrease in eGFR [ 21 ].…”

“…Furthermore, the results of multivariate logistic regression analysis demonstrated that the intensity of IgG deposition was associated with a poorer prognosis of the disease. This suggests that the severity or intensity of IgG deposition in the glomeruli may have an impact on the progression of IgAN and could be considered as a prognostic factor [ 20 ]. The greater potential of IgG deposits to initiate and sustain an inflammatory process may accelerate the progression of IgAN.…”