Effect of Lactobacillus brevis 119-2 isolated from turnip “Tsuda kabu” on hepatic cholesterol level in cholesterol-administrated rat

In previous in vitro study, we reported potential mechanism of cholesterol-lowering effect of Lactobacillus brevis119-2 (119-2) isolated from turnip “Tsuda kabu” is due to incorporation of cholesterol into 119-2 cell. In this study, we analyzed serum cholesterol and hepatic gene expression of Sprague-Dawley (SD) rat fed diet containing cholesterol with or without 119-2 for 2 weeks, to evaluate the cholesterol-lowering effect of 119-2 in vivo. Serum cholesterol of SD rat fed diet with 119-2 significantly decreased compared to SD rat fed diet without 119-2, and both viable and dead 119-2 indicated the effect. The result of hepatic gene analysis using DNA microarray suggested that potential mechanism of the cholesterol-lowering effect of 119-2 in vivo is inhibiting the activity of 3-hydroxy-3-methylglutaryl-CoA reductase by Insig (insulin induced gene) that is endoplasmic reticulum membrane protein, and catabolizing cholesterol to bile acid by Cyp7a1 (cytochrome P450 a1) that is the rate-limiting enzyme in the synthesis of bile acid from cholesterol. In addition, we concluded feeding 119-2 decreased serum low density lipoprotein (LDL) cholesterol by overexpression of Ldlr (LDL receptor gene). On the other hand, feeding Lactobacillus acidophilus ATCC43121 (ATCC) increased high density lipoprotein (HDL) cholesterol by over expression of Abca1 (ATP binding cassette sub-family A member 1 gene) and Angplt3 (Angiopoietin-like 3). These results suggested that 119-2 decrease the risk of atherosclerosis by serum cholesterol-lowering effect and improving effect of fatty liver and the LH (LDL cholesterol / HDL cholesterol) ratio.在前期体外研究中，我们曾报道从芜菁"Tsuda kabu"中分离得到的短乳杆菌（Lactobacillus brevis）119-2（下称119-2）的降胆固醇潜在机制，为将胆固醇掺入该菌株细胞内。本研究中，我们以饲喂含胆固醇日粮（添加/不添加119-2）2周的斯普拉格-道利（Sprague-Dawley, SD）大鼠为对象，分析其血清胆固醇水平与肝脏基因表达情况，以在体内层面评估119-2的降胆固醇效果。与饲喂不含119-2日粮的SD大鼠相比，饲喂添加119-2日粮的SD大鼠血清胆固醇水平显著降低，且活菌与灭活的119-2均展现出该降胆固醇效果。利用DNA微阵列（DNA microarray）开展的肝脏基因分析结果显示，119-2在体内的降胆固醇潜在机制为：通过内质网膜蛋白胰岛素诱导基因（Insig, insulin induced gene）抑制3-羟基-3-甲基戊二酰辅酶A还原酶的活性，并通过细胞色素P450 a1（Cyp7a1, cytochrome P450 a1，即胆固醇合成胆汁酸过程中的限速酶）将胆固醇代谢为胆汁酸。此外，我们得出结论：饲喂119-2可通过上调低密度脂蛋白受体基因（Ldlr, LDL receptor gene）的表达，降低血清低密度脂蛋白（LDL）胆固醇水平。另一方面，饲喂嗜酸乳杆菌（Lactobacillus acidophilus）ATCC43121（下称ATCC）可通过上调ATP结合盒转运蛋白A亚家族成员1基因（Abca1, ATP binding cassette sub-family A member 1 gene）与血管生成素样3（Angplt3, Angiopoietin-like 3）的表达，提升血清高密度脂蛋白（HDL）胆固醇水平。上述结果表明，119-2可通过降低血清胆固醇水平、改善脂肪肝状况以及调节低密度脂蛋白胆固醇/高密度脂蛋白胆固醇（LH, LDL cholesterol / HDL cholesterol）比值，降低动脉粥样硬化的发病风险。