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Intestinal ischemia-reperfusion (I/R) injury causes severe illness frequently complicated by remote multiorgan dysfunction and sepsis. Recent studies implicated interleukin-17A (IL-17A) in regulating inflammation, autoimmunity, and I/R injury. Here, we determined whether IL-17A is critical for generation of intestinal I/R injury and subsequent liver and kidney injury. Mice subjected to 30 min of superior mesenteric artery ischemia not only developed severe small intestinal injury (necrosis, apoptosis, and neutrophil infiltration) but also developed significant renal and hepatic injury. We detected large increases in IL-17A in the small intestine, liver, and plasma. IL-17A is critical for generating these injuries, since genetic deletion of IL-17A- or IL-17A-neutralizing antibody treatment markedly protected against intestinal I/R injury and subsequent liver and kidney dysfunction. Intestinal I/R caused greater increases in portal plasma and small intestine IL-17A, suggesting an intestinal source for IL-17A generation. We also observed that intestinal I/R caused rapid small intestinal Paneth cell degranulation and induced murine α-defensin cryptdin-1 expression. Furthermore, genetic or pharmacological depletion of Paneth cells significantly attenuated the intestinal I/R injury as well as hepatic and renal dysfunction. Finally, Paneth cell depletion significantly decreased small intestinal, hepatic, and plasma IL-17A levels after intestinal I/R. Taken together, we propose that Paneth cell-derived IL-17A may play a critical role in intestinal I/R injury as well as extraintestinal organ dysfunction. [ABSTRACT FROM AUTHOR]

Activation of A1 adenosine receptors (ARs) protects against renal ischemia-reperfusion (I/R) injury by reducing necrosis, apoptosis, and inflammation. However, extrarenal side effects (bradycardia, hypotension, and sedation) may limit A1AR agonist therapy for ischemic acute kidney injury. Here, we hypothesized that an allosteric enhancer for A1AR (PD-81723) protects against renal I/R injury without the undesirable side effects of systemic A1AR activation by potentiating the cytoprotective effects of renal adenosine generated locally by ischemia. Pretreatment with PD-81723 produced dose-dependent protection against renal I/R injury in A1AR wild-type mice but not in A1AR-deficient mice. Significant reductions in renal tubular necrosis, neutrophil infiltration, and inflammation as well as tubular apoptosis were observed in A1AR wild-type mice treated with PD-81723. Furthermore, PD-81723 decreased apoptotic cell death in human proximal tubule (HK-2) cells in culture, which was attenuated by a specific A1AR antagonist (8- cyclopentyl-1,3-dipropylxanthine). Mechanistically, PD-81723 induced sphingosine kinase (SK)1 mRNA and protein expression in HK-2 cells and in the mouse kidney. Supporting a critical role of SK1 in A1AR allosteric enhancer-mediated renal protection against renal I/R injury, PD-81723 failed to protect SK1-deficient mice against renal I/R injury. Finally, proximal tubule sphingosine-1-phosphate type 1 receptors (S1P1Rs) are critical for PD-81723-induced renal protection, as mice selectively deficient in renal proximal tubule S1P1Rs (S1P1Rflox/flox PEPCKCre/- mice) were not protected against renal I/R injury with PD-81723 treatment. Taken together, our experiments demonstrate potent renal protection with PD-81723 against I/R injury by reducing necrosis, inflammation, and apoptosis through the induction of renal tubular SK1 and activation of proximal tubule S1P1Rs. Our findings imply that selectively enhancing A1AR activation by locally produced renal adenosine may be a clinically useful therapeutic option to attenuate ischemic acute kidney injury without systemic side effects. [ABSTRACT FROM AUTHOR]

We studied centrifugation-mediated mechanical stress-induced tumor necrosis factor-α (TNF-α) production in the monocyte-like cell line THP-1. The induction of TNF-α by mechanical stress was dependent on the centrifugation speed and produced the highest level of TNF-α after 1 h of stimulation. TNF-α production returned to normal levels after 24 h of stimulation. Mechanical stress also induced Toll-like receptor-2 (TLR2) mRNA in proportion to the expression of TNF-α. The inhibition of TLR2 signaling by dominant negative myeloid differentiation factor 88 (MyD88) blocked TNF-α expression response to mechanical stress. After transient overexpression of TLR2 in HEK-293 cells, mechanical stress induced TNF-α mRNA production. Interestingly, mechanical stress activated the c-Src-dependent TLR2 phosphorylation, which is necessary to induce Ca2+ fluxes. When THP-1 cells were pretreated with BAPTA-AM, thapsigargin, and NiCl2∙6H2O, followed by mechanical stimulation, both TLR2 and TNF-α production were inhibited, indicating that centrifugation-mediated mechanical stress induces both TLR2 and TNF-α production through Ca2+ releases from intracellular Ca2+ stores following TLR2 phosphorylation. In addition, TNF-α treatment in THP-1 cells induced TLR2 production in response to mechanical stress, whereas the preincubation of anti-TNF-α antibody scarcely induced the mechanical stress-mediated production of TLR2, indicating that TNF-α produced by mechanically stimulated THP1 cells affected TLR2 production. We concluded that TNF-α production induced by centrifugation-mediated mechanical stress is dependent on MyD88-dependent TLR2 signaling that is associated with Ca2+ release and that TNF-α production induced by mechanical stress affects TLR2 production. [ABSTRACT FROM AUTHOR]