Combination of factor H mutation and properdin deficiency causes severe C3 glomerulonephritis

Area of Science:

• Immunology
• Nephrology
• Complement System Biology

Background:

• Factor H (fH) and properdin are key regulators of the alternative pathway of complement activation.
• fH inhibits complement activation, while properdin promotes it.
• fH mutations are linked to human kidney diseases, but the role of properdin in these conditions is unclear.

Purpose of the Study:

• To investigate the therapeutic potential of properdin blockade in fH mutation-associated kidney disease.
• To understand the complex role of properdin in the alternative complement pathway in the context of fH deficiency.

Main Methods:

• Utilized an fH-mutant mouse model of C3 glomerulonephritis (C3 GN).
• Employed genetic and pharmacological methods to block properdin activity.
• Analyzed the impact of properdin blockade on complement activation dynamics and kidney pathology.

Main Results:

• Genetic or pharmacological blockade of properdin transformed mild C3 GN into a lethal form in fH-mutant mice.
• The worsened pathology exhibited features similar to human dense deposit disease.
• Properdin blockade altered the dynamics of alternative complement pathway activation differently in fluid and cell-surface phases.

Conclusions:

• In fH mutation-related C3 glomerulopathy, properdin's role is complex and context-dependent.
• Therapeutic strategies targeting the complement system require disease-specific validation.
• The findings underscore the critical influence of alternative complement pathway regulators on kidney disease severity.