pf-543 and Hypoxia

Sphingosine kinase 1 (Sphk1), a key enzyme responsible for phosphorylating sphingosine into sphingosine1-phosphate (S1P), plays an important role in mediating post-stroke neuroinflammation. However, the pathway and mechanism of the Sphk1-mediated inflammatory response remains unknown. In this study, we found that suppression of Sphk1 decreased IL17 production and relieved neuronal damage induced by microglia in cerebral ischemia reperfusion (IR) or in an in vitro oxygen-glucose deprivation reperfusion (OGDR) system. Inhibition of Sphk1 with an inhibitor or siRNA decreased tumor necrosis factor receptor-associated factor 2 (TRAF2) and nuclear factor-kappa B (NF-κB) sequentially in microglia in response to IR or OGDR. Moreover, we also found that after suppression of TRAF2 or NF-κB by siRNA in microglia, reductions in the downstream molecules NF-κB and IL-17 and in neuronal apoptosis were observed in response to OGDR. Taken together, we hypothesize that Sphk1, TRAF2 and NF-κB form an axis that leads to increased IL-17 and neuronal apoptosis. This axis may be a potential therapeutic target to control neuroinflammation in brain IR.

Topics: Animals; Animals, Newborn; Cells, Cultured; Disease Models, Animal; Encephalitis; Glucose; Hypoxia; Infarction, Middle Cerebral Artery; Interleukin-17; Male; Methanol; Microglia; NF-kappa B; Phosphotransferases (Alcohol Group Acceptor); Pyrrolidines; Rats; Rats, Sprague-Dawley; Reperfusion; Signal Transduction; Sulfones; TNF Receptor-Associated Factor 2

Recent studies have demonstrated that the expression of sphingosine kinase 1, the enzyme that catalyses formation of the bioactive lipid, sphingosine 1-phosphate, is increased in lungs from patients with pulmonary arterial hypertension. In addition, Sk1(-/-) mice are protected from hypoxic-induced pulmonary arterial hypertension. Therefore, we assessed the effect of the sphingosine kinase 1 selective inhibitor, PF-543 and a sphingosine kinase 1/ceramide synthase inhibitor, RB-005 on pulmonary and cardiac remodelling in a mouse hypoxic model of pulmonary arterial hypertension. Administration of the potent sphingosine kinase 1 inhibitor, PF-543 in a mouse hypoxic model of pulmonary hypertension had no effect on vascular remodelling but reduced right ventricular hypertrophy. The latter was associated with a significant reduction in cardiomyocyte death. The protection involves a reduction in the expression of p53 (that promotes cardiomyocyte death) and an increase in the expression of anti-oxidant nuclear factor (erythroid-derived 2)-like 2 (Nrf-2). In contrast, RB-005 lacked effects on right ventricular hypertrophy, suggesting that sphingosine kinase 1 inhibition might be nullified by concurrent inhibition of ceramide synthase. Therefore, our findings with PF-543 suggest an important role for sphingosine kinase 1 in the development of hypertrophy in pulmonary arterial hypertension.

Topics: Animals; Biomarkers; Body Weight; Cells, Cultured; Disease Models, Animal; Enzyme Inhibitors; Female; Heart Ventricles; HEK293 Cells; Humans; Hypertension, Pulmonary; Hypertrophy, Right Ventricular; Hypoxia; Methanol; Mice, Inbred C57BL; Models, Biological; Myocytes, Smooth Muscle; Phosphotransferases (Alcohol Group Acceptor); Piperidines; Pressure; Pulmonary Artery; Pyrrolidines; Signal Transduction; Sulfones; Ventricular Remodeling