Back to Search
Start Over
Sepsis induces an increase in thick ascending limb Cox-2 that is TLR4 dependent
- Source :
- The American Journal of Physiology. Oct, 2007, Vol. 293 Issue 4, pF1187, 10 p.
- Publication Year :
- 2007
-
Abstract
- Cyclooxygenase-2 (Cox-2) is an inducible enzyme responsible for the formation of inflammatory prostanoids such as prostaglandins and thromboxane. Its role in the pathophysiology of inflammatory states like sepsis is increasingly recognized. Recently, we demonstrated that sepsis up-regulates the endotoxin receptor Toll-like receptor 4 (TLR4) in rat kidney. Because Cox-2 is one of the downstream products of TLR4 activation, we hypothesized that sepsis-induced changes in renal Cox-2 expression are TLR4 dependent. Indeed, we show that in Sprague-Dawley rats, cecal ligation and puncture (a sepsis model) increases Cox-2 expression in cortical and medullary thick ascending loops (cTAL and mTAL, respectively) as well as inner medullary collecting ducts. These are all sites of increased TLR4 expression during sepsis. To determine the actual dependence on TLR4, we measured Cox-2 expression in wild-type and mutant mice which harbor a TLR4 gene deletion (TLR4-/-). In wild-type mice, sepsis increased Cox-2 expression in proximal tubules, cTAL, and mTAL. In contrast, septic TLR4-/- mice showed no significant increase in cTAL or mTAL Cox-2 expression. Furthermore, renin was absent from juxtaglomerular cells of TLR4-/- mice. We conclude that the dependence of sepsis-induced renal Cox-2 expression on TLR4 is tubule specific. The TLR4-dependent Cox-2 expression is mostly restricted to cortical and medullary thick ascending loops of Henle that characteristically express and secrete Tamm-Horsfall protein. Toll-like receptors; renin; Tamm-Horsfall protein; macula densa; cyclooxygenase
Details
- Language :
- English
- ISSN :
- 00029513
- Volume :
- 293
- Issue :
- 4
- Database :
- Gale General OneFile
- Journal :
- The American Journal of Physiology
- Publication Type :
- Academic Journal
- Accession number :
- edsgcl.181072020