Role of complement in renal tubular damage

Area of Science:

• Nephrology
• Immunology
• Pathology

Background:

• The complement system is crucial in immune responses but can cause tissue damage when dysregulated.
• Tubulointerstitial lesions are a common feature of chronic kidney disease and are associated with poor prognosis.

Purpose of the Study:

• To investigate the deposition patterns of immunoglobulins and complement proteins in the renal tubulointerstitium.
• To determine the association between complement deposition and tubulointerstitial lesions in glomerular diseases.

Main Methods:

• Immunofluorescence microscopy was used to examine serial sections of renal tissue from 45 patients with glomerular diseases and 8 controls.
• Deposition of immunoglobulins and complement proteins (C1q, C3c, C3d, C4, C5-C9, terminal complement complex neoantigens) was assessed.

Main Results:

• Immunoproteins were deposited in the tubular basement membrane and blood vessels.
• Significantly increased staining for C5-C9 was observed in the tubular basement membrane of both disease groups compared to controls.
• Terminal complement complex neoantigen deposition was significantly higher in the group with tubulointerstitial lesions.

Conclusions:

• In situ activation of the complement cascade results in terminal complement complex neoantigen deposition.
• Complement activation in the tubular basal area is a significant pathogenetic mechanism contributing to tubulointerstitial damage.