Moreover, tonic S1P2R activation by endogenous S1P places brake on additional S1P generation by reducing SK1 synthesis and activity

Moreover, tonic S1P2R activation by endogenous S1P places brake on additional S1P generation by reducing SK1 synthesis and activity. and attenuated both H2O2-induced necrosis and TNF-was critical in mediating the renoprotective effects of S1P2R inhibition. Finally, induction of SK1 and S1P2R Clemizole hydrochloride in response to renal IR and S1P2R antagonism occurred selectively in renal proximal tubule cells but not in renal endothelial cells. Taken together, these data suggest that S1P2R may be a therapeutic target to attenuate the effects of renal IR injury. AKI is a major clinical complication with high mortality, morbidity, and cost.1,2 Renal ischemia and reperfusion (IR) injury is a major cause of perioperative AKI for patients undergoing surgery involving the kidney, liver, or aorta.3,4 Unfortunately, the severity and incidence of AKI have been increasing, without any improvements in therapy or patient survival over the past 50 years.5 The incidence of renal dysfunction in high-risk patients after major cardiovascular, hepatobiliary, or aortic surgery approaches 70%C80%.3,4,6 Despite continued research searching for renal protective agents, there are no confirmed therapies to reduce AKI in the perioperative setting1,7 Sphingolipids are pleiotropic regulators of kidney physiology that modulate diverse pathways Clemizole hydrochloride of cell death, including necrosis, apoptosis, inflammation, and immunity.8,9 In particular, phosphorylation of sphingosine by sphingosine kinases (SK1 and SK2) leads to the formation of sphingosine 1-phosphate (S1P), a lysophospholipid targeting G-proteinCcoupled receptor that has diverse extracellular as well as intracellular effects.9 Of five G-proteinCcoupled receptors for S1P, activation of endothelial S1P1R receptor (S1P1R) reduces permeability and maintains the integrity of the vascular endothelial cell barrier.10 S1P1R activation also protects against cardiac,11,12 renal,13,14 and hepatic15 IR injury and inflammation. In contrast, S1P2R activation may have the opposite effects, with potentially adverse vascular signaling Clemizole hydrochloride events.16 These previous studies suggest that a balance of S1P1R and S1P2R activation may modulate the tissue response to endogenous and exogenous S1P.17,18 However, unlike the better-characterized role of the S1P1R, the role of the S1P2R in tissue injury secondary to IR remains unclear. Moreover, the direct renal tubular effects of S1P2R activation have never been described. In this study, we Clemizole hydrochloride aimed to test the role of S1P2R in modulating renal injury after IR. Results Pharmacologic Blockade, Genetic Deletion, or Knockdown of S1P2R Protects against Renal IR Injury in Mice We initially tested the effects of selective S1P1R (W146), S1P2R (JTE-013), or S1P3R (CAY10444) RGS21 blockade on renal IR injury in mice (Physique 1A); all drugs were given at a dose of 0.1 mg/kg body wt intraperitoneally 10 minutes before and 30 minutes after renal ischemia. Renal IR caused statistically significant increases in plasma creatinine in all groups. However, blockade of the S1P2R produced significant renal protection against IR injury compared with vehicle-treated mice. Neither S1P1R nor S1P3R antagonist pretreatment affected renal IR injury. We subsequently showed dose-dependent renal protection with JTE-013, 0.05C0.1 mg/kg injected intraperitoneally 10 minutes before and 30 minutes after renal ischemia, which produced maximal renal protection in mice after IR injury (Determine 1B). We also tested whether blockade of S1P2R after renal ischemia guarded against renal IR injury. Figure 1C shows that JTE-013, 0.1 mg/kg, injected intraperitoneally 10 minutes before ischemia or 30 minutes after reperfusion protected against renal IR injury. However, JTE-013 administered 60 minutes after reperfusion did not produce renal protection after IR. Open in a separate window Physique 1. S1P2R activation modulates renal injury after IR. (A) Treatment with a selective S1P2R inhibitor (JTE-013; 0.1 mg/kg interperitoneally 10 minutes before and 30 minutes after renal.