| 摘要: | 有機磷農藥陶斯松(Chlorpyrifos, CPF)為使用歷史悠久且用途廣泛之殺蟲劑，近年來研究發現CPF除了神經毒性外，亦會造成體內氧化壓力升高與血糖血脂等生化指標異常。糖尿病(diabetes mellitus, DM)為慢性發炎疾病，當組織器官長期暴露於高血糖環境下，會使氧化壓力升高，引起發炎反應而造成器官損傷。目前研究並不清楚飲食中暴露CPF是否會使高血糖所引起的發炎反應加劇，故本研究使用8週齡雄性C57BL/6J小鼠，以連續五天腹腔注射鏈脲佐菌素(streptozotocin, 50 mg/kg/day)誘發高血糖，探討飲食暴露CPF對於DM小鼠免疫細胞比例以及發炎反應之影響。實驗期間所有小鼠皆給予AIN-93飼料，而CPF暴露組則於飼料中混入不同濃度之CPF，其濃度分別為3.5、7和14 ppm，共進行28天飲食介入。結果顯示，與正常小鼠相比，DM小鼠有較高的血糖和糖化血色素，體重與血漿胰島素濃度則是顯著下降。飲食暴露CPF的DM小鼠，其血液中的調節型T細胞(regulatory T cell, Treg)、輔助型T細胞與胞毒型T細胞比率下降。在脾臟中，DM小鼠暴露CPF後使促凋亡指標Bim及細胞增殖細胞激素IL-2基因表現量提升，且抗凋亡指標Bcl-2基因表現量下降，促發炎細胞激素IL-6及IL-17 mRNA表現量亦提升。此外，飲食暴露CPF會使DM小鼠的副睪脂肪中促發炎型巨噬細胞(inflammatory macrophage, 又稱M1 Mφ)比率上升，且M1 Mφ/抗發炎巨噬細胞(anti-inflammatory macrophage, 又稱M2 Mφ)之比例變高，單核球趨化因子(C-C motif ligand 2, CCL2)、腫瘤壞死因子α (tumor necrosis factor-α)與介白素1β (interleukin-1β)的基因表現提升，而脂聯素(adiponectin)的基因表現量降低；肝臟中則觀察到M1 Mφ比率上升與Treg細胞比率下降，以及CCL2基因表現量提升與乙型轉化生長因子(transforming growth factor-β)的基因表現量下降，但肝臟組織切片並沒有明顯的變化。綜合上述，飲食中暴露CPF 28日，會降低DM小鼠血液與肝臟中Treg比率，促使副睪脂肪與肝臟中的M1 Mφ浸潤，並提升促發炎因子的表現，然而組織形態上並無明顯的變化。
Chlorpyrifos (CPF), an organophosphate pesticide, is widely used to control insects in agriculture and household environments worldwide. In addition to its neurotoxic effects, recent studies indicated that CPF induced oxidative stress, and altered blood glucose and lipid metabolism in vivo. Diabetes mellitus (DM) is a metabolic disorder disease with abnormally high levels of blood glucose. Hyperglycemia induces oxidative stress which leads to inflammation and causes organ injuries. This study investigated the effects of dietary exposure to CPF on immune cell populations and inflammatory responses in C57BL/6 mice with DM. C57BL/6J mice were randomly assigned to five groups with one normal control (N), one DM control (D) and three CPF-exposed DM groups. Hyperglycemia was induced by repeated intraperitoneal injection of streptozotocin (50 mg/kg/day) for 5 consecutive days. The N and D groups were fed the AIN-93 diet, while the remaining DM groups were given a CPF diet containing 3.5, 7, or 14 ppm of CPF throughout a 28-day dietary intervention study. Results showed that DM mice had higher levels of blood sugar and hemoglobin A1c, and lower body weights and plasma insulin concentrations than those of the N group. Compared to the D group, dietary exposure to CPF in DM mice significantly decreased circulating regulatory T cells (Tregs), T helper cells and cytotoxic T cells. In the spleen, CPF-exposure upregulated the gene expressions of Bim and interleukin (IL)-2, as well as downregulated the gene expressions of Bcl-2. Furthermore, the splenic expressions of IL-6 and IL-17 gene were also upregulated. M1 macrophages (Mφ) infiltration into the epididymal fat was observed in CPF exposure groups. The mRNA expressions of C-C motif ligand 2 (CCL2), tumor necrosis factor-α and IL-1β were upregulated, whereas the expression level of adiponectin gene was downregulated in epididymal fat of CPF-exposed mice. CPF exposure groups had higher percentages of M1 Mφ and lower percentages of Tregs in the liver. CPF also upregulated the hepatic gene expressions of CCL2 and IL-1β and downregulated the gene expressions of transforming growth factor-β. However, there were no significant changes in liver histology. These findings suggest that dietary exposure to CPF suppressed the Treg populations in blood and liver, elevated the percentages of M1 Mφ in the liver and adipose tissue, and upregulated the expression of inflammatory genes without affecting liver morphology. |
