Background

Serpina3 is a member of the serine protease inhibitor family and is involved in the inflammatory response. In this study, we investigated the effect of Serpina3c on pancreatic function in hypercholesterolemic mice.

Methods

To investigate the role of Serpina3c in hyperlipidaemia, Serpina3c knockout mice were bred with Apoe-knockout mice (on a C57BL/6 background) to generate heterozygous Serpina3c-Apoe double knockout (Serpina3c^+/−/Apoe^+/−) mice and were then bred to obtain homozygotes. C57BL/6, Serpina3c^−/−, Apoe^−/−, and Apoe^−/-Serpina3c^−/− mice were fed normal chow, and Apoe^−/− and Apoe^−/-Serpina3c^−/− mice were fed a high-fat diet (HFD). After feeding for 3 months, the mice were monitored for body weight, blood glucose, glucose tolerance, and insulin tolerance test (ITT). ELISA and immunohistochemistry were used to detect insulin levels and glucagon expression. Immunohistochemical staining for macrophages in the pancreas was also performed. Western blot analysis was performed on pancreatic tissues to detect the protein levels of insulin-associated molecules, the metalloproteinase MMP2, the tissue inhibitor TIMP2 and components of the JNK-related pathway.

Results

Blood glucose levels, glucose tolerance, and ITT were not significantly different among the groups. Serpina3c knockout resulted in blood lipid abnormalities in mice under HFD conditions. Insulin secretion was decreased in Apoe^−/-Serpina3c^−/− mice compared with Apoe^−/− mice under normal chow conditions. In addition, Apoe^−/-Serpina3c^−/− mice exhibited increased insulin and glucagon secretion and expression after three months of HFD feeding, but insulin secretion was decreased in Apoe^−/-Serpina3c^−/− mice compared with Apoe^−/− mice after the fifth month of HFD feeding. Serpina3c knockout increased MMP2 protein levels, whereas TIMP2 levels in the pancreas were decreased. Furthermore, Serpina3c knockout significantly upregulated the number of macrophages in the pancreas under HFD conditions. The JNK/AKT/FOXO1/PDX-1 axis was found to be involved in Serpina3c-regulated insulin secretion.

Conclusion

These novel findings show that Serpina3c could play a protective role in insulin secretion partly through the JNK-related pathway under HFD conditions.

中文翻译：

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Serpina3c 通过 JNK 相关途径防止高脂肪饮食引起的胰腺功能障碍。

背景

Serpina3 是丝氨酸蛋白酶抑制剂家族的成员，参与炎症反应。在这项研究中，我们研究了 Serpina3c 对高胆固醇血症小鼠胰腺功能的影响。

方法

为了研究 Serpina3c 在高脂血症中的作用，将 Serpina3c 基因敲除小鼠与 Apoe 基因敲除小鼠（在 C57BL/6 背景下）饲养以产生杂合 Serpina3c-Apoe 双基因敲除（Serpina3c ^+/- /Apoe ^+/-）小鼠，然后繁殖以获得纯合子。C57BL/6、Serpina3c ^-/-、Apoe ^-/-和Apoe ^-/- Serpina3c ^-/-小鼠喂食正常食物，Apoe ^-/-和Apoe ^-/- Serpina3c ^-/-小鼠被喂食高脂肪饮食（HFD）。喂养3个月后，监测小鼠的体重、血糖、葡萄糖耐量和胰岛素耐量试验（ITT）。ELISA和免疫组织化学用于检测胰岛素水平和胰高血糖素表达。还对胰腺中的巨噬细胞进行了免疫组织化学染色。对胰腺组织进行蛋白质印迹分析，以检测胰岛素相关分子、金属蛋白酶 MMP2、组织抑制剂 TIMP2 和 JNK 相关通路成分的蛋白质水平。

结果

各组之间的血糖水平、葡萄糖耐量和 ITT 没有显着差异。Serpina3c 敲除导致 HFD 条件下小鼠血脂异常。胰岛素分泌是在降低的ApoE ^{- / -} Serpina3c ^{- / -}小鼠与ApoE相比^{/ - -}正常食物情况下的小鼠。此外，APOE ^{- / -} Serpina3c ^{- / -}小鼠表现出3个月HFD喂养后增加的胰岛素和胰高血糖素分泌和表达，但是胰岛素分泌是在降低的ApoE ^{- / -} Serpina3c ^{- / -}小鼠与ApoE相比^{- / -}HFD喂养第五个月后的小鼠。Serpina3c 敲除增加了 MMP2 蛋白水平，而胰腺中的 TIMP2 水平降低。此外，在 HFD 条件下，Serpina3c 敲除显着上调了胰腺中巨噬细胞的数量。发现 JNK/AKT/FOXO1/PDX-1 轴参与 Serpina3c 调节的胰岛素分泌。

结论

这些新发现表明，在 HFD 条件下，Serpina3c 可以部分通过 JNK 相关途径在胰岛素分泌中发挥保护作用。