MC-LR对草鱼肠道显微结构和炎症相关细胞因子表达的影响

Effects of Microcystin-LR on the microstructure and inflammation-related cytokines of intestine in grass carp(Ctenopharyngodon idella)

微囊藻毒素-LR(MC-LR)是蓝藻水华暴发产生的一种毒素,在水生生态系统中广泛分布.为探讨MC-LR对鱼类的肠道免疫毒性,分别对草鱼经腹腔注射不同剂量的MC-LR(25、75和100μg·kg-1),24、48、72和96 h后取样,分别进行组织病理变化和炎症相关细胞因子表达分析.显微结构结果显示,肠道组织病理变化表现为微绒毛结构破坏并伴随淋巴细胞浸润,肠上皮细胞排列紊乱,杯状细胞数目显著增多,粘膜固有层充血,在高剂量组甚至出现粘膜固有层分离的现象,且有剂量和时间效应.采用荧光定量PCR方法检测了炎症相关细胞因子IL-1β、IL-8、IL-10、TNF-α和TGF-β的mRNA转录水平变化.结果显示促炎性细胞因子IL-1β、IL-8和TNF-α表达在低剂量组显著上升,而在高剂量组的表达多被抑制;而抗炎性细胞因子IL-10 mRNA仅在25μg·kg-1BW处理组表达差异变化显著,但在高剂量组表达变化差异不显著,TGF-β1的表达仅在75和100μg·kg-1处理组分别处理72和24 h后显著降低,其他差异不显著.从以上结果推测MC-LR的肠道免疫毒性主要表现为肠黏膜结构的破坏以及产生炎性反应,其中对肠黏膜结构的破坏具有剂量依赖效应.

Microcystin-LR （MC-LR） is one of the toxins generated by the blue-green algae blooms, and it extensively distributes in the aquatic ecosystem. In order to investigate the immune toxicity of MC-LR to intestine, the grass carp （ Ctenopharyngodon idella） individuals were injected intraperitoneally with 25, 75 and 100 μg MC-LR/kg body weight （ μg · kg^-1 ）, respectively, the intestine samples were took for microstructure and expressions of inflammation-related eytokines at 24, 48, 72 and 96 b. The pathological changes of intestinal tissue were characterized by the destruction of microvilli with lymphocytic infiltration, arranging in disorder of intestinal epithelial cells, significantly increasing of the number of goblet ceils, and the congestion of the mucous membrane even the lining of the mueosa being separated in higher doses of groups. The damage was with a time and dose dependent manner. Another, the expressions of inflammation-related cytokines, including interleukin-1β （ IL-1β）, interleukin-8 （ IL-lβ）, tumor necrosis factor a （ TNF-α）, interleukin-lO （1L-10） and transforming growth factor-ill （TGF-fll） in the intestines were investigated by using quantitative real-time PCR （qRT-PCR）. The results of qRT-PCR showed that the pro-inflammation eytokines, including IL-1β, IL-8 and TNF-α, were significantly upregnlated in the low dose of group, however, the expressions were significantly depressed in high dose of groups. Another, the anti-inflammation cytokine, the expressions of IL-10 were significantly upregulated at 24 h in 25 μg.kg^-l body weight group, then significantly depressed, however, the changes of IL-10 mRNA in higherdose groups were not significant. Furthermore, the expressions of TGF^I were significantly downregulated just at 24 and 72 h respectively in 75 and 100 μg·kg-1 BW groups, and the expression of TGF-β 1 in other groups were not significant. Taking together, it was clearly demonstrated that MC-LR could damage the intestine mucosal structure of grass carp with dose independent effects and induced the inflammation reaction.