肥大细胞在急性应激性肠黏膜屏障损伤中的作用机制

摘要

背景:应激所致肠黏膜屏障损伤的机制以及肥大细胞(MC)在其中的作用尚未明确.目的:探讨肠黏膜MC(IMMC)在急性应激性肠黏膜屏障损伤中的作用机制.方法:Sprague-Dawley(SD)大鼠随机分为正常对照组(N组)、应激组(S组),S组给予急性冷束缚应激建立模型,按照应激结束后处死时间进一步分为S2h、S4h、S8h、S16h、S24h组.取回肠末端观察组织病理学改变,以Chiu's评分评估肠黏膜组织损伤程度,以甲苯胺蓝染色计数IMMC,以透射电镜观察肠黏膜组织和IMMC超微结构,以ELISA法检测肠黏膜组织组胺含量.结果:S组的Chiu's评分均显著高于N组(P<0.05),呈先升后降的趋势,以S8h组最高.S2h、S4h 组的IMMC计数显著高于N组(P<0.05),S8h、S16h、S24h 组IMMC计数与N组相比差异无统计学意义(P>0.05).IMMC计数与Chiu's评分无相关性(P>0.05).S组肠黏膜超微结构破坏明显,IMMC胞质大量脱颗粒.S2h、S4h、S8h 组的肠黏膜组织组胺含量较N组显著降低(P<0.05),呈逐渐下降趋势.S16h、S24h 组组胺含量与N组相比差异无统计学意义(P>0.05).肠黏膜组织组胺含量与Chiu's评分呈负相关(P＝0.03).结论:急性应激状态下,IMMC脱颗粒释放炎性介质是导致肠黏膜屏障损伤的重要机制.%Background: The mechanism of stress induced intestinal barrier injury and the mechanistic role of mast cells ( MC ) have not yet been clarified. Aims: To investigate the mechanistic role of intestinal mucosal MC ( IMMC ) in acute stress induced intestinal mucosal barrier injury. Methods: Sprague-Dawley ( SD ) rats were randomly divided into normal control group ( N group ) and stress group ( S group ). Rats in S group were given acute cold/restraint stress and were further divided into S2h, S4h, S8h, S16h and S24h subgroups according to the time point of sacrificing after stress. Histological change of terminal ileum tissue was observed and the degree of damage was evaluated by Chiu s scoring system. IMMC number was counted by toluidine blue staining. The ultrastructure of intestinal tissue and IMMC was observed by transmission electron microscopy. The content of histamine in intestinal tissue was determined by ELISA. Results: Chiu s score in S subgroups was significantly higher than that in N group ( P < 0.05 ), showing a crescendo-decrescendo trend with the highest value occurred in S8h subgroup. Compared with N group, IMMC counts in S2h and S4h subgroups were significantly increased ( P<0.05 ), and no significant difference was found between S8h, S16h, S24h subgroups and N group ( P > 0. 05 ). IMMC count was not correlated with Chiu' s score ( P > 0. 05 ). Severe ultrastructure damage of intestinal mucosa and degranulation of IMMC were observed in S subgroups. The content of histamine in S2h, S4h and S8h subgroups was significantly lower than that in N group ( P < 0.05 ), showing a decrescendo trend. No significant difference was found between S16h, S24h subgroups and N group ( P>0.05 ). The histamine content was negatively correlated with Chiu's score ( P = 0. 03 ). Conclusions: IMMC degranulation with release of inflammatory mediators is an important mechanism of acute stress induced intestinal mucosal barrier injury.