Mesangial C4d Deposits in Early IgA Nephropathy

Area of Science:

• Nephrology
• Immunopathology
• Renal Medicine

Background:

• IgA nephropathy (IgAN) is a common glomerular disease.
• Prognostic value of mesangial C4d deposits is established in IgAN with reduced GFR.
• Limited data exists on C4d deposits in IgAN patients with normal GFR.

Purpose of the Study:

• To investigate the prognostic significance of mesangial C4d deposits in IgA nephropathy patients with normal GFR.
• To assess the association of C4d deposits with treatment response in this patient group.

Main Methods:

• Retrospective cohort study of 190 IgAN patients with GFR ≥ 80 ml/min/1.73 m² at diagnosis.
• Analysis of kidney biopsy paraffin-embedded samples for mesangial C4d deposits.
• Long-term follow-up (median 15 years) assessing clinical outcomes and treatment responses.

Main Results:

• Mesangial C4d deposits were found in 20% of patients.
• C4d-positive patients had higher proteinuria and more nephritic flares at diagnosis.
• C4d-positive patients experienced greater eGFR decline and required more corticosteroid treatments.
• Mesangial C4d deposits independently predicted poorer long-term kidney survival.

Conclusions:

• Mesangial C4d deposits may serve as an early negative prognostic marker in IgAN patients with normal kidney function.
• C4d deposits alone do not predict response to angiotensin blockers or corticosteroids.
• Further research is needed to understand the role of C4d in IgAN pathogenesis and management.