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C3 dependent, C5 independent immune complex glomerulopathy in the mouse
N M Sawtell1, A L Hartman, M A Weiss
1Department of Pathology, University of Cincinnati Medical Center, Ohio.
Summary
Complement component C3, not C5, is crucial for immune complex glomerulopathy development in mice. C3 deficiency prevents kidney injury and alters immune complex localization, suggesting a role in their glomerular basement membrane passage.
Area of Science:
- Immunology
- Nephrology
- Complement System Biology
Background:
- Immune complex glomerulopathy is a kidney disease characterized by inflammation and damage to the glomeruli.
- The complement system, a crucial part of innate immunity, plays a role in various inflammatory conditions, including kidney diseases.
Purpose of the Study:
- To investigate the specific role of complement components, particularly C3 and C5, in a murine model of accelerated immune complex glomerulopathy.
- To determine if complement activation is necessary for the development of proteinuria and glomerular injury in this model.
- To elucidate the influence of complement on the localization and movement of immune complexes within the glomeruli.
Main Methods:
- Utilized C5 deficient mouse strains (DBA/2J, B10.D2oSnJ) and normocomplementemic mice.
- Induced immune complex glomerulopathy via intravenous antigen administration.
- Depleted C3 in some mice using cobra venom factor.
- Assessed proteinuria, glomerular architecture, and immune complex deposition (antigen and antibody) semiquantitatively.
Main Results:
- Both C5 deficient and normocomplementemic mice developed heavy proteinuria and glomerular injury.
- C3-depleted mice failed to develop proteinuria and maintained normal glomerular structure.
- Immune complex deposition was equivalent across groups, but localization differed: subepithelial in C5 deficient/normocomplementemic mice, subendothelial in C3-depleted mice.
- C3-depleted mice showed immune deposits that did not cross the glomerular basement membrane.
Conclusions:
- Glomerular injury in this model is dependent on complement components up to C3, but not C5 or later components.
- C3 plays a significant role in the movement of immune complexes across the glomerular basement membrane.
- Complement mediates injury independently of inflammatory cell infiltration or terminal complement components in this model.