Abstract: Objective To investigate theeffect of miR-24 and S100A8 in exosomes of an in vitro kidney stone cell model on kidney stone disease and the underlying mechanism. Methods Human proximal tubular epithelial HKC-8 cells were used to establish a kidney stone cell model in vitro. HKC-8 cells were divided into four groups: the control group, the model group, the miR-24mimic + model group (miR-24 mimic was transfected into the cells of the model group), and the mimic NC + model group (mimic NC was transfected into the cells of the model group). Bioinformatics analysis was performed to analyze the relationship of miR-24 and S100A8 3′-UTR by using TargetScan v7. 2. Dual luciferase reporter assay was used to verify the direct interactions between miR-24 and S100A8 3′-UTR. Exosomes were extracted. The levels of miR-24 in exosomes was determined by qPCR. Western blotting was used to determine the protein expression levels of CD9, CD63 and S100A8 in exosomes, and the protein expression levels of PINK1, Parkin and Cytochrome C (Cyt-C) in cells. The levels of inflammatory cytokines TNF-α, IL-1β and IL-6 in cell supernatants and malondialdehyde ( MDA) in cells were determined by ELISA. The levels of reactive oxygenspecies ( ROS) were determined by DCFH-DA fluorescent dye method. Results Dual luciferasereporter assays had proved a direct interactions between miR-24 and S100A8 3′-UTR. miR-24 wasdown-regulated and S100A8 was up-regulated in the exosomes of the Model group (P< 0. 05), the expression levels of mitophagy markers of PINK1, Parkin and Cytochrome C were up-regulated (P<0. 05), the intracellular ROS and MDA levels were up-regulated (P< 0. 05), TNF-α, IL-1β andIL-6 were up-regulated in cell supernatants in the Model group ( P < 0. 05) when compared withthose in the Control group. The above indexes were all partially reversed in the miR-24 mimic + Model group (P< 0. 05), while there had been no significant difference in the mimic NC + Model group(P > 0. 05) when compared with those in the Model group. Conclusion MiR-24 was down-regulated and as “spongy” of S100A8 in exosomes of kidney stone cell model to up-regulate S100A8 expression, enhance mitochondrial damage and promote kidney stone disease.

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