飼糧誘發肥胖迷你豬的心包油特徵

Abstract

白色脂肪組織主要作為儲存身體能量的地方，近年來文獻指出內臟脂肪組織 (Visceral adipose tissue, VAT)具有較高的代謝活性，可以藉釋出 Adiponectin 以及 Interleukin-6 (IL-6)等因子藉由旁分泌或是血管分泌影響周邊組織。內臟脂肪相較於皮下脂肪具有較高的代謝活性，在肥胖患者中內臟脂肪釋放更多的發炎因子進入血液循環中。Epicardial adipose tissue (EAT) 及 Pericardial adipose tissue (PAT)為貼附於心臟周圍及位在心包膜內之脂肪組織。許多文獻指出，EAT及 PAT具有內臟脂肪之特性，且心臟油脂與心血管疾病、血管鈣化及區域發炎反應呈現正相關。因此，在本實驗中會利用飼料誘導李宋豬產生肥胖，並探討健康及肥胖患者中EAT、PAT及 VAT 之特性。 使用來自台大牧場六月齡李宋豬進行實驗，隨機分配成 Control diet (C)及Western diet (W)共 2 組，並進行 6 個月飼料誘導。實驗結束後，W 組相較於 C 組出現血脂異常及心臟纖維化。W組有較多 VAT 及 PAT ; 而 EAT 在兩組之間無明顯差異。 W 組豬隻 VAT 及 PAT 脂肪顆粒主要分佈在大於 10000 μm2，而 C 及 W組之 EAT 則主要分佈在小於 10000 μm2。分析組織脂肪酸組成發現， W 組之 VAT 及 PAT 中 MUFA 增加， EAT 則無。利用脂質過氧化作為氧化壓力之指標， W 組 PAT 及血液相較於 C 組高， EAT 在兩組間則無差異。在 W 組不同脂肪組織中，脂質過氧化程度呈現： PAT> VAT> EAT 之情況。由此可知W組出現循環系統及 PAT 誘導區域性之氧化壓力。以 IL-6 作為發炎之指標， W 組之血液、PAT 及 VAT 顯著高於 C 組。由上述結果得知，餵飼李宋豬高油脂飼料 6 個月後，VAT 及 PAT 會產生功能異常。 豬隻犧牲後取 VAT 及 PAT 進行體外培養並收取培養後之 Conditional medium (CM) 進行後續分析。結果顯示脂質過氧化程度及 IL-6 濃度在 CMPW (W組PAT之CM)及 CMVW (W 組 VAT 之 CM)相較於各自 C 組高。總抗氧化能力分析上，CMP (PAT 之 CM )相較 CMV 低，而 Control 組總抗氧化能力又高於 Western 組。最後，我們進行不同 CM 處理心肌細胞則發現，相較於 Complete medium，不論是Control 或是 Western 組皆會造成心肌細胞凋亡。 綜合以上結果，長期餵飼李宋豬西方飼糧成功誘導肥胖及心臟纖維化產生。分析不同脂肪組織則發現 VAT 及 PAT 產生功能異常，EAT 則無此現象。在 CM分析上則發現，Western 組相較 Control 組含有較高氧化壓力以及 IL-6。分析細胞存活率試驗則發現，相較於 Complete medium ，所有 CM 皆會使細胞存活率降低。

White adipose tissue has been regarded as energy storage tissue. Recently, several studies reported that white adipose tissue exhibits metabolic active properties and secretes bioactive factors, including adiponectin and Interleukin 6 (IL-6), for a crosstalk with other organs by vasocrine or paracrine. Compared with subcutaneous adipose tissue, visceral adipose tissue (VAT) owns highly lipolytic activity and secrets a great amount of pro-inflammatory factors with enhanced adiposity. Epicardial adipose tissue (EAT) and pericardial adipose tissue (PAT) are fat next to heart and share similar characteristics with VAT. Numbers results have proved that excess of PAT and EAT highly is highly associated with cardiovascular disease, artery calicification and local inflammation. To elucidate the link between adipose tissue and cardiac injury induced by obesity, the characteristics of adipose tissues (VAT, PAT and EAT) via our obesity-induced cardiomyopathy minipig model. Six-month-old Lee-Sung minipigs were randomly assigned into two groups: control diet (C) and Western diet (W), for a 6-month experimental period. Compared with C group, W pigs exhibited dyslipidemia and cardiac fibrosis. W pigs had more VAT and PAT than C group, while C and W pigs had a similar amount of EAT. Bigger adipocyte size were observed in PAT and VAT of W pigs (> 10000 μm2) , whereas smaller adipocyte size was found in EAT (< 10000 μm2) . Similar fatty acid composition of VAT and PAT was observed in which monounsaturated fatty acid (MUFA) fraction was upregulated in W pigs, and no difference were observed in EAT between C and W pigs. In TBARS analyzed, an oxidative stress marker defined by lipid per-oxidation, W pigs exhibited higher levels of TBARS in the blood and PAT than C pigs, while no differences were found in the EAT. In W pigs, the TBARS levels were PAT> VAT > EAT, suggesting that systemic and local oxidative stress were induced in W pigs, and the local effect by PAT should considered. IL-6 was applied as the inflammatory marker. Greater IL6 levels were found in the plasma, PAT and VAT of W pigs than those in C pigs. In our results suggesting that high fat diet feeding for 6-month may influence PAT and VAT dysfunction in Lee-Sung minipigs. Adipocytes of VAT and PAT were isolated and cultured in vitro, the conditional medium (CM) were collected for further in vitro study. The composition of CM were analyzed. Higher levels of TBARS and IL-6 were observed in CM from PAT and VAT of W pigs. Compared with complete medium, all CM treatments for 24 hr decreased H9c2 survival rate. CM from PAT exhibited less total antioxidative capacity than that from VAT, and higher antioxidative capacity was observed in C groups. We treated H9c2 with different CM. Compared to complete medium, both C and W groups induced H9c2 cell death. Taken together, long term consumption of Western diet induced obesity and cardiac fibrosis in Lee-Sung minipig. VAT and PAT dysfunction, but not in EAT, were observed in this study. In CM analysis, higher amount of oxidative stress and IL-6 were observed in VAT and PAT of W groups. Comparing with complete medium, all groups of CM decreased cell survival rate.