Introduction: Growing number of studies suggest that PSGN and glomerular diseases as a strong risk factor for chronic kidney disease (CKD). Earlier studies suggests that the secretory streptococcal antigens such as streptococcal inhibitor of Complement (SIC) have a role in pathogenesis of CKD or End stage renal disease (ESRD) based on serological evidence. In current study, we investigated whether deposits of SIC and its variants such as Distantly related to SIC (DRS) and DRSG (orthologue of DRS) are present in kidney tissues from glomerular disease patients.
Methods: 25 patients diagnosed with glomerular diseases and for control 25 age-matched autopsies whose deaths were unrelated to renal disorders were recruited for this study. Sections of kidney tissues were tested for deposition of SIC, DRS and DRSG by immunofluorescence. Antibodies to these antigens were also tested.
Results: In the glomerular disease study cohort, 28% and 16 % were positive for anti-SIC and anti-DRSG antibodies respectively as opposed to only 4% in the cadaver cohort (p=0.0007 and 0.0182 respectively). Also, a significant number of patients suffering from glomerular diseases (7/25; 28%, p = 0.0488) were positive for deposition of SIC in kidney sections in comparison to cadavers. No significant differences were found for deposition of DRS and DRSG between these cohorts.
Conclusion: This immunohistological and serological study suggests a role for SIC in pathogenesis of glomerular diseases. The findings of the present work strongly favour serology for anti-SIC antibodies as an important tool for poor prognostic marker in the management of glomerular diseases.