Yan Meiling, Chen Kankai, He Li, Li Shuai, Huang Dong, Li Jingbo
Department of Cardiology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
Department of Nephrology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China.
Cell Physiol Biochem. 2018;45(5):2122-2135. doi: 10.1159/000488048. Epub 2018 Mar 7.
BACKGROUND/AIMS: Hyperuricemia is associated with an increased risk for multiple cardiovascular diseases, but the underlying mechanisms remain largely elusive. Calpain-1 is a protease that is implicated in several pathological conditions that affect the heart. The aim of this current study was to test the effects of uric acid (UA) on cardiomyocyte survival and cardiac function and to investigate the role of calpain-1 in the UA-induced effects in the heart and their underlying mechanisms.
In vivo, hyperuricemia was induced by oxonic acid (OA) administration in Sprague-Dawley rats for 16 weeks; TUNEL staining was used to identify apoptotic cells. Left ventricular (LV) sections were stained with Sirius Red to evaluate interstitial fibrosis. Cardiac catheterization was performed to evaluate cardiac function. In vitro, cultured H9c2 cells were incubated with different UA concentrations. MTT assays and flow cytometry were used to evaluate cell viability and apoptosis. All related gene expression levels were analyzed by quantitative real-time PCR (qRT-PCR), and all protein expression levels were analyzed by western blotting.
Hyperuricemia induction in vivo resulted in cellular apoptosis, interstitial fibrosis and diastolic dysfunction in the rat hearts, as well as increased activation of calpain-1 and endoplasmic reticulum (ER) stress, while allopurinol treatment mitigated the above changes. UA administration in vitro increased apoptosis and decreased H9c2 cell viability in a dose-dependent manner. Increased activation of calpain-1 and ER stress was also observed in the groups with high UA levels. Calpain-1 siRNA and the calpain inhibitor CI-III alleviated UA-induced ER stress and apoptosis, while inhibiting ER stress by tauroursodeoxycholic acid (TUDCA) mitigated UA-induced apoptosis without affecting calpain-1 expression or activity.
These findings suggest that UA induces cardiomyocyte apoptosis through activation of calpain-1 and ER stress. These results may provide new insights into the mechanisms of hyperuricemia-associated cardiovascular risks and hopefully identify new treatment targets.
背景/目的：高尿酸血症与多种心血管疾病风险增加相关，但其潜在机制仍大多不明。钙蛋白酶-1是一种蛋白酶，与影响心脏的多种病理状况有关。本研究的目的是测试尿酸（UA）对心肌细胞存活和心脏功能的影响，并研究钙蛋白酶-1在UA诱导的心脏效应中的作用及其潜在机制。
在体内，通过向Sprague-Dawley大鼠给予氧嗪酸钾（OA）16周诱导高尿酸血症；采用TUNEL染色鉴定凋亡细胞。左心室（LV）切片用天狼星红染色以评估间质纤维化。进行心脏导管插入术以评估心脏功能。在体外，将培养的H9c2细胞与不同浓度的UA孵育。采用MTT法和流式细胞术评估细胞活力和凋亡。通过定量实时PCR（qRT-PCR）分析所有相关基因表达水平，通过蛋白质印迹法分析所有蛋白质表达水平。
体内诱导高尿酸血症导致大鼠心脏细胞凋亡、间质纤维化和舒张功能障碍，以及钙蛋白酶-1和内质网（ER）应激的激活增加，而别嘌醇治疗减轻了上述变化。体外给予UA以剂量依赖性方式增加凋亡并降低H9c2细胞活力。在高UA水平组中也观察到钙蛋白酶-1和ER应激的激活增加。钙蛋白酶-1小干扰RNA和钙蛋白酶抑制剂CI-III减轻了UA诱导的ER应激和凋亡，而通过牛磺熊去氧胆酸（TUDCA）抑制ER应激减轻了UA诱导的凋亡，而不影响钙蛋白酶-1的表达或活性。
这些发现表明，UA通过激活钙蛋白酶-1和ER应激诱导心肌细胞凋亡。这些结果可能为高尿酸血症相关心血管风险的机制提供新见解，并有望确定新的治疗靶点。
