Complement-mediated dysfunction of glomerular filtration barrier accelerates progressive renal injury

Area of Science:

• Nephrology
• Immunology
• Complement System

Background:

• Intrarenal complement activation contributes to tubulointerstitial injury in proteinuric nephropathies.
• The complement system, particularly C3, is a potential therapeutic target for kidney disease.

Purpose of the Study:

• To investigate the role of the C3-mediated pathway in promoting renal injury in a protein overload model.
• To determine if proximal tubular cells' exposure to filtered complement triggers an inflammatory response.

Main Methods:

• Utilized C3-deficient mice and wild-type (WT) mice in a protein overload model.
• Employed kidney transplantation between C3-deficient and WT mice.
• Administered angiotensin-converting enzyme inhibitor (lisinopril) to WT mice.

Main Results:

• C3 deficiency significantly protected against interstitial inflammation, tissue damage, podocyte injury, and proteinuria.
• Antiproteinuric treatment reduced C3 accumulation and protected against inflammation and damage.
• Plasma-derived C3 exacerbated glomerular and tubulointerstitial injury more than locally synthesized C3.

Conclusions:

• The presence of C3 increases glomerular filtration barrier susceptibility to injury.
• Ultrafiltered C3 significantly contributes to tubulointerstitial damage in protein overload.
• Combined therapies targeting complement and proteinuria may effectively prevent chronic kidney disease progression.