Complement 3 is involved in changing the phenotype of human glomerular mesangial cells

Area of Science:

• Nephrology
• Immunology
• Cell Biology

Background:

• Complement activation is implicated in glomerulopathy and chronic kidney disease progression.
• Complement component 3 (C3) is linked to vascular smooth muscle cell synthetic phenotype.
• C3 may induce glomerular injury by stimulating mesangial cell transformation.

Purpose of the Study:

• To investigate the role of C3 in human mesangial cell (HMC) growth and phenotype.
• To determine if C3a influences HMC synthetic or contractile characteristics.
• To assess the impact of C3 inhibition on HMC behavior.

Main Methods:

• Cultured HMCs were analyzed for C3 and C3a receptor expression.
• HMCs were treated with exogenous C3a, and gene expression was measured.
• Small interfering RNA (siRNA) targeting C3 was used to inhibit C3 function.
• Cellular proliferation and gene markers of contractile/synthetic phenotypes were assessed.

Main Results:

• HMCs express C3 and its receptor; C3 expression increases with IFN-gamma and TNF-alpha.
• Exogenous C3a stimulated HMC DNA synthesis and promoted a synthetic phenotype (increased osteopontin, matrix Gla, collagen IV; decreased h-caldesmon, alpha-smooth muscle actin).
• siRNA-mediated C3 inhibition reduced HMC proliferation and reversed the phenotypic shift towards a contractile state.

Conclusions:

• C3 promotes HMC conversion to a synthetic phenotype and stimulates cell growth.
• C3 signaling plays a significant role in regulating mesangial cell phenotype.
• Targeting C3 may offer a therapeutic strategy for mitigating renal disease progression.