陈醋抑制草酸钙肾结石的表观遗传调控机制研究

Epidemiological evidence suggests that daily intake of vinegar is associated with a reduced risk of nephrolithiasis. Individuals with daily consumption of vinegar compared to those without have a higher urinary citrate excretion and lower urinary calcium excretion. This evidence indicates dietary vinegar might suppress nephrolithiasis through regulating urinary secretion of citrate and calcium. Using rat model, we found oral administration of vinegar or its principle bioactive component, acetate, reduced renal calcium oxalate (CaOx) crystals formation likely through increased citrate and reduced calcium in urinary excretion, two critical molecules for CaOx crystals formation. Mechanism dissection suggested that vinegar or acetate can suppress the expression Nadc1 and Cldn14, thus enhancing urinary citrate excretion and reducing urinary calcium excretion. However, the mechanism how vinegar or acetate regulate Nadc1 and Cldn14 remains largely unknown. Previous literatures showed that acetate could function as an epigenetic metabolite to regulate gene expression. Our preliminary data also showed vinegar or acetate treatment could increase histone acetylation level and microRNAs that potentially regulate Nadc1 and Cldn14 in CaOx nephrolithiasis rat model. We therefore hypothesize that vinegar of acetate could suppress CaOx nephrolithiasis through influencing urinary citrate and calcium excretion via epigenetic regulations. In the present study, we will further investigate the detail molecular mechanism how vinegar or acetate function via epigenetic regulation of Nadc1 and Cldn14 to suppress the CaOx nephrolithiasis, which will help us to develop a better approach to prevent or suppress CaOx nephrolithiasis.

流行病学调查显示食用陈醋与肾结石形成呈负相关性，日常食醋人群其尿液枸橼酸高于对照人群，尿钙低于对照人群，提示陈醋可能具有调节尿液成分并抑制结石形成的效果。前期结果显示陈醋及其主成分醋酸可通过抑制肾小管Nadc1和Cldn14表达增加尿枸橼酸并减少尿钙排泄，从而抑制了大鼠肾脏草酸钙晶体形成。然而陈醋中的醋酸如何调控Nadc1和Cldn14影响草酸钙结石形成的机制仍未阐明。既往研究报道醋酸可通过表观遗传调控方式调节基因的表达，我们前期结果也显示陈醋或醋酸干预可增加肾小管组蛋白乙酰化水平及相关miRNA表达，推测陈醋中醋酸可通过上调肾小管组蛋白乙酰化水平及miRNA表达从而抑制了Nadc1和Cldn14的表达，改善了尿枸橼酸及钙排泄最终减少草酸钙结石的形成。本项目拟进一步阐明陈醋及醋酸抑制草酸钙结石形成的表观遗传调控机制，证实上述设想的正确性，为陈醋预防草酸钙结石形成及复发提供理论和实验基础。

全国流行病学调查显示日常食用陈醋与肾结石形成呈负相关，然而其具体机制仍不明确。本项目通过体外及体内实验探寻陈醋及其主要成分醋酸的抗结石作用。实验结果显示日常喝醋人群尿枸橼酸（一种可以抑制结石形成的物质）明显高于对照人群，而尿钙（一种促进结石形成的物质）明显低于对照人群。动物实验发现：服用陈醋或者5%醋酸后，尿液成分改善，肾脏草酸钙晶体沉积减少。在进一步分子机制研究中，细胞及动物实验结果表明陈醋中的醋酸，可以促进肾小管细胞的组蛋白H3K9及H3K27的乙酰化水平，随后激活了microRNA-130a-3p，-148b-3p和-374b-5p的表达，从而分别抑制了位于肾近端小管的Nadc1枸橼酸转运体，以及位于髓袢的Cldn14钙离子转运体，进而减少了肾脏枸橼酸重吸收并增加了钙重吸收，导致了尿液中枸橼酸含量增加以及减少了尿钙的排泄，最终抑制了尿液中草酸钙晶体的形成。本项目最终证实了陈醋可通过表观遗传调控作用影响尿枸橼酸及尿钙的排泄从而抑制肾结石形成及复发。