Circulating alternative pathway complement cleavage factor Bb is associated with vascular lesions and outcomes in IgA...

Area of Science:

• Nephrology
• Immunology
• Complement System Biology

Background:

• Immunoglobulin A nephropathy (IgAN) prognosis is linked to complement alternative pathway (AP) activation.
• The specific role of the Bb fragment in IgAN severity and outcomes remains unclear.

Purpose of the Study:

• To investigate the association between serum Bb fragment concentration at diagnosis and disease activity in IgAN patients.
• To evaluate the predictive value of serum Bb fragment levels for long-term outcomes in IgAN.

Main Methods:

• Retrospective study of 125 biopsy-proven IgAN patients with long-term follow-up.
• Serum Bb fragment levels measured by ELISA at diagnosis.
• Pathology assessed using Oxford classification and global optical score (GOS).

Main Results:

• Higher serum Bb fragment concentration correlated with lower eGFR and worse histopathological indices.
• Elevated Bb fragment levels were associated with increased risk of end-stage kidney disease (ESKD).
• Patients with Bb levels ≥14.3 μg/ml had significantly shorter kidney survival.

Conclusions:

• Serum Bb fragment concentration at diagnosis may serve as a predictive biomarker for long-term IgAN outcomes.
• AP activation, potentially at the endothelial surface, might explain the observed association.
• Further research is warranted to validate these findings and explore Bb fragment's therapeutic potential in IgAN.