Platelet-derived miR-92a downregulates cysteine protease inhibitor cystatin C in type II diabetic lower limb ischemia.

The aim of the present study was to investigate the effect of microRNA (miR)-92a on cystatin C expression in patients with type II diabetes and lower limb ischemia. A total of 199 patients diagnosed with type II diabetes were included in the study and divided into three experimental groups: Simple type II diabetes mellitus (T2DM; n=60) group; type II diabetes with light to moderate occlusion (LLI-LM; n=70) group; and the type II diabetes with severe occlusion (LLI-S; n=69) group according to the patient ankle-brachial index score. In addition, 60 healthy individuals were examined as a control population. The expression levels of various biochemical indices were detected, including cystatin C in the peripheral blood. The expression levels of miR-92a and cystatin C mRNA were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and the correlation between miR-92a, cystatin C and the pathological development of type II diabetic lower limb ischemia was analyzed. The protein expression levels of cystatin C were detected using western blot analysis. Bioinformatic analysis indicated that miR-92a was able to downregulate cystatin C expression, and this result was supported by endothelial cell transfection. In the transfection assay, an miR-92a mimic downregulated cystatin C expression, while an miR-92a inhibitor upregulated cystatin C expression. The results of the RT-qPCR indicated that the expression levels of miR-92a in the LLI-S group were reduced compared with those in the T2DM and LLI-LM groups, and significantly lower compared with those in the negative control group. Platelet-derived miR-92a appeared to downregulate cystatin C expression in patients with type II diabetes and lower limb ischemia. Therefore, the combined detection of miR-92a and cystatin C may be useful as a method for clinically screening patients with type II diabetes for lower limb ischemia.