篩選具有抗肥胖功效的潛力乳酸菌株

Abstract

隨著人類生活水平的提升,肥胖已成為現代人不可忽視的文明病之一。在造成代謝系統失調的同時也提升了第二型糖尿病、心血管疾病和非酒精性脂肪肝等疾病發生風險。目前針對肥胖治療主要分為服用減肥藥或進行減重手術兩種方法，但此二者都會對人體造成一定程度的影響。故近幾年許多研究都在致力於開發更為安全的減肥策略。乳酸菌作為一個普遍運用在人類食品加工的微生物，已在許多動物實驗模型中被證明具有能夠降低血酯、抗發炎、抗肥胖等諸多功效。而益生菌主要歸類於乳酸菌群，更被證明在大量攝取後能夠對人體腸道菌群造成顯著影響，能透過各種途徑調節宿主的能量及代謝平衡，並在影響新陳代謝的情況，具有治療肥胖症狀的潛力。本研究的目的為以3T3-L1細胞和高脂飼料所誘導的SD大鼠為試驗模型，篩選出具有抗肥胖潛力的乳酸菌株，同時評估它們是否有成為益生菌的發展性。根據結果顯示，YPK11和YPK12兩株菌的處理不僅顯著降低成熟脂肪細胞中的脂質含量水平，還下調了脂肪生成相關基因，C/EBPα和PPARγ的表達，並在抑制脂肪堆積的同時還造成了細胞週期的延滯進而影響細胞分化。在益生菌潛力的評估中，這兩株菌在pH 3的酸性環境下具有一定的耐受性，其菌株的代謝物也擁有抗部分病原菌的活性。此外、根據動物實驗的結果顯示，在餵食8週後，高劑量的YPK11顯著減輕了用高脂飼料誘導肥胖的老鼠體重，而血清和肝臟的三酸甘油脂水平也有降低的趨勢，並同時影響了脂肪生成和代謝相關基因，SREBP1c 和 CPT-1的表現。 而通過利用第三代定序技術的腸道菌相分析結果顯示，與一般肥胖對照組的老鼠相比，在充分補充YPK11後能夠顯著改變肥胖鼠的腸道菌群組成。我們的研究表明，YPK11和YPK12 的處理能通過多種機制來影響成熟脂肪細胞中的脂質積累，並能抑制脂肪細胞生成; 而YPK11在動物試驗也表現出其能夠影響肥胖動物模型的腸道菌群並具有抗肥胖的潛力。

With changes in lifestyles, obesity has become a common chronic symptom of modern people. Abnormal or excessive fat accumulation is considered to be the main contributor to obesity, which in turn causes metabolic disorders and the occurrence of various diseases. Probiotics are living microorganisms, mainly lactic acid bacteria (LAB), that can improve human intestinal microbial balance and possess the potential anti-obesity ability by regulating lipid and glucose metabolism. Based on clinical evidence, current anti-obesity drugs are discovered to bring several side effects to the human body; in our study, we aimed to screen potential LAB strains with the anti-obesity ability and determined their effects on high-fat-diet (HFD)-induced obese rat model. During cell differentiation and adipogenesis, 3T3-L1 adipocytes, a widely used cell model in metabolism research, were treated with cell-free extracts (CFE) from two identified LAB strains, YPK11, and YPK12. According to the results, treatments with both strains not only significantly decreased the levels of lipid content in adipocytes but also down-regulated the expression of adipogenic-related genes. Cell cycle arrest and the reduction of cell proliferation rates were also observed in cell cycle assays after CFE treatment. In the subsequent study, the in vivo test was performed to examine the effects of YPK11 and YPK12 on HFD-induced obese rats. After eight weeks of feeding, the administration of high dose YPK11 (1010 CFU in 0.2 mL PBS/kg BW/day) appeared to alleviate body weight gain and adipose tissue amount, whereas the decreasing trend of cholesterol and total triglyceride levels in serum and liver were also observed. Moreover, the results of gut microbiota analysis, performed by third-generation sequencing, indicated that gut microbiota composition changed after feeding the obese rats with sufficient YPK11 compared to the HFD control group. In conclusion, our studies revealed that the treatment of YPK11 and YPK12 affected the lipid accumulation in mature adipocytes by multiple mechanisms and ultimately caused adipogenesis inhibition, while YPK11 also showed potential anti-obesity ability in vivo. Our study provides an opportunity to determine other LAB strains with the same function and bring a different strategy for treating obesity in the future.