Complement regulation in the rat glomerulus: Crry and CD59 regulate complement in glomerular mesangial and...

Area of Science:

• Immunology
• Nephrology
• Cell Biology

Background:

• Complement regulators, including decay accelerating factor, membrane cofactor protein, and CD59, are found in human glomeruli.
• Crry serves as the rodent analog to decay accelerating factor and membrane cofactor protein.
• Understanding complement regulation in glomerular cells is crucial for kidney health.

Purpose of the Study:

• To investigate the presence and function of complement regulators Crry and CD59 in cultured rat glomerular endothelial cells (GEnC) and mesangial cells (MES).
• To elucidate the roles of Crry and CD59 in regulating both the classical and alternative complement pathways in these specific kidney cell types.

Main Methods:

• Immunoprecipitation and Western blotting were used to detect Crry and CD59 proteins in GEnC and MES.
• Northern analysis identified mRNA expression for Crry and CD59.
• Functional assays involved activating complement pathways (classical and alternative) and assessing cytotoxicity upon inhibition of Crry and CD59 using specific antibodies.

Main Results:

• Crry proteins (53, 65, 78 kD) and CD59 (20 kD) were detected in GEnC and MES, with varying expression levels.
• Crry mRNA was present in both cell types, and CD59 mRNA was found in GEnC and whole glomeruli.
• Inhibition of Crry function significantly increased cytotoxicity in both cell types, particularly via the alternative pathway. CD59 inhibition had a minor effect in MES but was functional in GEnC.

Conclusions:

• Crry is a key regulator of the alternative complement pathway in both rat glomerular endothelial and mesangial cells.
• Crry also plays a role in regulating the classical complement pathway in mesangial cells.
• CD59 is functionally active in glomerular endothelial cells but has a limited role in mesangial cells regarding complement regulation.