[HTML][HTML] Altered renal tubular expression of the complement inhibitor Crry permits complement activation after ischemia/reperfusion

JM Thurman, D Ljubanović, PA Royer… - The Journal of …, 2006 - Am Soc Clin Investig
JM Thurman, D Ljubanović, PA Royer, DM Kraus, H Molina, NP Barry, G Proctor, M Levi
The Journal of clinical investigation, 2006Am Soc Clin Investig
Ischemia/reperfusion (I/R) of several organs results in complement activation, but the kidney
is unique in that activation after I/R occurs only via the alternative pathway. We hypothesized
that selective activation of this pathway after renal I/R could occur either because of a loss of
complement inhibition or from increased local synthesis of complement factors. We
examined the relationship between renal complement activation after I/R and the levels and
localization of intrinsic membrane complement inhibitors. We found that loss of polarity of …
Ischemia/reperfusion (I/R) of several organs results in complement activation, but the kidney is unique in that activation after I/R occurs only via the alternative pathway. We hypothesized that selective activation of this pathway after renal I/R could occur either because of a loss of complement inhibition or from increased local synthesis of complement factors. We examined the relationship between renal complement activation after I/R and the levels and localization of intrinsic membrane complement inhibitors. We found that loss of polarity of complement receptor 1–related protein y (Crry) in the tubular epithelium preceded activation of the alternative pathway along the basolateral aspect of the tubular cells. Heterozygous gene-targeted mice that expressed lower amounts of Crry were more sensitive to ischemic injury. Furthermore, inhibition of Crry expressed by proximal tubular epithelial cells in vitro resulted in alternative pathway–mediated injury to the cells. Thus, altered expression of a complement inhibitor within the tubular epithelium appears to be a critical factor permitting activation of the alternative pathway of complement after I/R. Increased C3 mRNA and decreased factor H mRNA were also detected in the outer medulla after I/R, suggesting that altered synthesis of these factors might further contribute to complement activation in this location.
The Journal of Clinical Investigation