microRNA-98 mediated microvascular hyperpermeability during burn shock phase via inhibiting FIH-1

BACKGROUND microRNA is a small non-coding RNA molecule and functions in RNA silencing and post-transcriptional regulation of gene expression. This study was designed to evaluate the role of miR-98 in the development of microvascular permeability and its molecular pathogenesis. METHODS Forty-eight healthy adult Wistar rats were divided into the control group (n = 8) and burn group (n = 40) that inflicted with 30% total body surface area third-degree burn. Groups were processed at 2, 4, 8, 12, and 24 h post-burn. Plasma for vascular endothelial cell culture was collected from control and 12 h post-burn rats. Organic microvascular permeability and serum miR-98 level were measured. In vitro, rat aorta endothelial cells were stimulated with burn serum. Level of miR-98 and protein of hypoxia-inducible factor-1 (HIF-1), factor inhibiting HIF-1α (FIH-1), and tight junction-associated proteins were determined. RESULTS Organic microvascular permeability began to rise at 2 h post-burn and maintained the same character throughout the experiment except in lung tissue that was still rising at 12 h; the serum level of miR-98 was elevated (P < 0.05). In vitro, burn serum stimulation increased rat aorta endothelial monolayer cell permeability as well as upregulated miR-98 expression (P < 0.05). As shown in the result of transfection experiment, miR-98 negatively regulated FIH-1 and tight junction-associated protein expression (P < 0.05). CONCLUSIONS The findings of the present study suggest severe microvascular permeability due to burns; and the underlying mechanism bases on the promotion of miR-98 level to the extent that it activated HIF-1 gene expression, resulting in junction-associated protein deficiency.