Interaction of uromodulin and complement factor H enhances C3b inactivation

Area of Science:

• Nephrology
• Immunology
• Molecular Biology

Background:

• Uromodulin is implicated in chronic kidney diseases and interacts with immune components.
• Complement factor H (CFH) regulates the complement alternative pathway and is linked to renal diseases.

Purpose of the Study:

• To investigate the interaction between uromodulin and CFH in the context of tubulointerstitial injury.
• To determine if uromodulin regulates complement activation through CFH.

Main Methods:

• Immunofluorescence to detect co-localization of uromodulin and CFH in renal tubules.
• Surface plasmon resonance to confirm in vitro binding and determine affinity.
• Identification of CFH binding sites for uromodulin.

Main Results:

• Uromodulin and CFH co-localize in renal tubules.
• Uromodulin binds to CFH with an affinity constant (KD) of 4.07 × 10⁻⁶ M.
• Binding occurs at specific short consensus repeat (SCR) units on CFH (SCR1-4, SCR7, SCR19-20).
• The uromodulin-CFH interaction enhances CFH's cofactor activity in cleaving C3b to iC3b.

Conclusions:

• Uromodulin plays a role in renal tubulointerstitial injury by interacting with and enhancing the function of CFH.
• This interaction modulates complement activation, suggesting a therapeutic target for kidney diseases.