不同聚合度的卡拉胶降解物对人结肠上皮细胞的影响

Effects of Degraded Carrageenan with Different Level of Polymerization on Human Colonic Epithelial Cells

目的:探讨结构因素对卡拉胶降解物安全性的影响。方法:以结肠上皮细胞(Caco-2)为研究对象,通过MTT法检测3种类型的卡拉胶(κ,ι和λ型)在3种聚合度范围内的细胞毒,并通过测定活性氧、NO、TNF-α、IL-8的变化来观察样品对细胞的致炎能力。结果:硫酸基团含量最低的κ-卡拉胶降解物具有最强的细胞毒,而硫酸基团含量最高的λ-卡拉胶细胞毒性最弱。其中κ-卡拉胶低聚物在质量浓度高于200μg/mL时的存活率低于30%,并且这种细胞毒与活性氧的爆发呈明显相关性。同时,κ-卡拉胶低聚物具有最强的促进炎症因子分泌的能力,NO、TNF-α、IL-8都出现了明显的增高。另外,聚合度也是影响卡拉胶细胞毒性和促炎性因子分泌的关键,聚合度越低,毒性越高,炎症因子的分泌量越大。结论:低聚卡拉胶,特别是κ-型卡拉胶能够通过活性氧的爆发造成结肠上皮细胞损伤,并引起大量炎症因子产生。该机制可能会导致卡拉胶低聚物损伤结肠组织,引发结肠溃疡。

Objective： To assess the association between structural information and safety aspect of carrageenan to human colonic epithelial ceils （Caco-2）. Methods： The cytotoxic effect of three forms of carrageenan, known as kappa, iota and lambda with different degree of polymerization （DP） on Caco-2 cells were examined by MTT method. The proinflammatory effect were also evaluated by detecting content of the ROS, NO, IL-8 and TNF-α. Results： Degraded κ- carrageenan with lowest sulfate content showed the highest cytotoxicity against Caco-2, while k type carrageenan which has more sulfate substitute exhibited mild cytotoxic effect. Ceils treated with low molecular weight kappa-carrageenan at concentration〉200 μg/mL exhibited high cytotoxic （survival ratio 〈30%）, and this cytotoxic response was stimulated by ROS. κ-Carrageenan oligosaccharides were more effective than other samples in inducing some inflammatory cytokines. They can evoke significantly more IL-8, TNF-α, NO and ROS release from Caco-2 cells. Molecular weight of degraded carrageenan is another critical factor for induction of cytotoxicity and secretion of inflammatory cytokines. Lower DP of carrageenan correlated to the higher level of IL-8, TNF-α, NO, ROS and toxicity. Conclusion： These results suggest that exposure to low DP carrageenan, especially degraded κ-carrageenan could trigger the injury of colonic epithelial cells by inducing the explosion of ROS and secretion of inflammatory cytokines. These injury and immune response may promote the intestinal ulcerations and induce inflammatory bowel disease.