Effects of 5,14-HEDGE, a 20-HETE mimetic, on lipopolysaccharide-induced changes in MyD88/TAK1/IKKβ/IκB-α/NF-κB pathway and circulating miR-150, miR-223, and miR-297 levels in a rat model of septic shock.

Abstract

We have previously demonstrated that a stable synthetic analog of 20-hydroxyeicosatetraenoic acid (20-HETE), N-(20-hydroxyeicosa-5[Z],14[Z]-dienoyl)glycine (5,14-HEDGE), which mimics the effects of endogenously produced 20-HETE, prevents vascular hyporeactivity, hypotension, tachycardia, inflammation, and mortality in a rodent model of septic shock. The present study was performed to determine whether decreased renal and cardiovascular expression and activity of myeloid differentiation factor 88 (MyD88)/transforming growth factor-activated kinase 1 (TAK1)/inhibitor of κB (IκB) kinase β (IKKβ)/IκB-α/nuclear factor-κB (NF-κB) pathway and reduced circulating microRNA (miR)-150, miR-223, and miR-297 expression levels participate in the protective effect of 5,14-HEDGE against hypotension, tachycardia, and inflammation in response to systemic administration of lipopolysaccharide (LPS). Conscious male Wistar rats received saline (4ml/kg) or LPS (10mg/kg) at time 0. Blood pressure and heart rate were measured using a tail-cuff device. Separate groups of LPS-treated rats were given 5,14-HEDGE (30mg/kg) 1h after injection of saline or LPS. The rats were killed 4h after LPS challenge and blood, kidney, heart, thoracic aorta, and superior mesenteric artery were collected for measurement of the protein expression. LPS-induced fall in blood pressure and rise in heart rate were associated with increased MyD88 expression and phosphorylation of TAK1 and IκB-α in cytosolic fractions of the tissues. LPS also caused an increase in both unphosphorylated and phosphorylated NF-κB p65 proteins in the cytosolic and nuclear fractions as well as nuclear translocation of NF-κB p65. In addition, serum miR-150, miR-223, and miR-297 expression levels were increased in LPS-treated rats. These effects of LPS were prevented by 5,14-HEDGE. These results suggest that downregulation of MyD88/TAK1/IKKβ/IκB-α/NF-κB pathway as well as decreased circulating miR-150, miR-223, and miR-297 expression levels participate in the protective effect of 5,14-HEDGE against hypotension, tachycardia, and inflammation in the rat model of septic shock.