探討體外與體內lunasin處理對免疫細胞與C57BL/6肥胖小鼠免疫反應之影響

Abstract

流行病學調查顯示，全球肥胖盛行率依然居高不下，而在肥胖過程中，脂肪組織會有免疫細胞浸潤，並伴隨促發炎性細胞激素的分泌，導致生理處於慢性低度發炎狀態，進而造成許多疾病發展，如：代謝症候群、第二型糖尿病、心血管疾病與癌症等。Lunasin為一種子胜肽，存在於許多穀類中，由43個胺基酸組成，目前研究證實lunasin具有抗腫瘤、抗氧化、抗發炎和免疫調節等功能。本實驗目的為探討肥胖狀態下，lunasin的免疫調節效果。體外實驗的部分，在細胞培養時添加leptin或脂肪細胞培養液 (Adipocyte condition medium) 來模擬肥胖微環境，結果顯示在肥胖環境下，lunasin處理能夠促進EL-4 T細胞增殖，增加IL-2和IL-10分泌量，並降低IL-4分泌；而在肥胖因子下，lunasin處理不影響RAW264.7巨噬細胞胞飲及吞噬活性。體內實驗的部分，將小鼠分為五組，分別為低脂 (LF組)、高脂 (HF組)、腹腔注射lunasin 4 or 20 mg/kg體重 (HF-LL及HF-HL組)以及飲食中添加富含lunasin的天然大豆蛋白萃取物 (HF-DL組)(每公斤飼料含有107 mg lunasin)。結果顯示，HF組相較於LF組，小鼠體重、內臟脂肪及脾臟重量顯著較高，而相較於HF組，lunasin處理對體重及脂肪生成沒有影響，但lunasin處理顯著降低脾臟重量，雖然脾臟細胞數目相對減少，然而在Con A刺激下，脾臟細胞的增殖率卻顯著提升。HF組相較於LF組，在LPS刺激下，腹腔巨噬細胞的TNF-α分泌有較高的趨勢，脾臟細胞的IL-6及PGE2分泌則顯著較高，IL-4分泌顯著較低。而腹腔注射lunasin組小鼠脾臟細胞在LPS刺激下，其IL-6與TNF-α分泌有降低的趨勢；而在Con A刺激下，顯著增加IL-2和IL-4分泌量，且有降低IL-1β的趨勢。綜合上述，lunasin具有緩解肥胖造成脾臟腫大的效果，並改善由肥胖造成的淋巴細胞增殖能力降低，且能夠抑制肥胖造成促發炎細胞激素的分泌，並影響T細胞細胞激素的分泌。總結上述，顯示lunasin在肥胖環境下，具有調控免疫細胞生長與細胞激素分泌等免疫調節的作用。其他免疫調節的功能評估，有待後續進一步的探討。

The prevalence of obesity is increasing since 1980s, and obesity becomes a worldwide healthy issue. In adiposity, immune cells infiltrate into adipose tissue and produce pro-inflammatary cytokines caused chronic inflammation. Obesity is associated with the development of metabolic syndrome, type 2 diabetes mellitus, cardiovascular diseases, cancer etc. Lunasin is a seed peptide found in soybean and other seeds. Lunasin consists of 43 amino acid and has been reported multiple biofunctions such as anti-tumor, anti-oxidation, and anti-inflammation effects. However, there is still few information of lunasin affects on metabolic disease. The aim of this study is to explore the immunomodulation of lunasin in obese models in vitro and in vivo. In vitro, the result has shown that lunasin increased EL-4 T cell proliferation, and IL-2 and IL-10 productions induced by phorbol myristate acetate and ionomycin in T cells under obese models of recombinant mouse leptin or adipocyte condition medium (Ad-CM) to mimic the physiological conditions of obesity. However, lunasin did not affect pinocytosis and phagocytosis activity of RAW264.7 cells. In vivo, C57BL/6 mice were divided into five groups: low-fat diet (LF), high-fat diet (HF), intraperitoneal injection with lunasin 4 or 20 mg/kg body weight/day (HF-LL and HF-HL), and lunsin-enriched soy extract in diet (HF-DL) (107 mg lunasin/kg diet) for 8 weeks. The body weight, and the weight of white adipose tissue and spleen in mice of HF group were higher than those in LF group. In contrast, the size of spleen oflunasin groups were smaller than that in HF group. The proliferation of splenocytes of HF-LL group by concanavalin A (Con A) stimulation was higher compared to the HF group. Moreover, lunasin inhibited secretions of IL-6 and TNF-α, and promoted productions of IL-2 and IL-4 in splenocytes by mitogen stimulation. These results suggested that lunasin regulates T cells proliferation and cytokines production in obese models both in vitro and in vivo. Further studies need to investigate and clarify about the mechanisms of action of lunasin on immunomodulation.