The correlation analysis of intestinal mucosal barrier function damage with systemic inflammation reaction during severe heatstroke / 中华危重病急救医学

ABSTRACT

Objective To observe the effect of severe heatstroke on intestinal mucosal barrier function,and explore its correlation with systemic inflammatory reaction.Methods The SPF male BALB/c mice were randomly divided into normal control group,40 ℃ heat stress group and 42 ℃ heat stress group,with 6 mice in each group.The mice in normal control group were observed at normal temperature with (25.0 ± 0.5)℃,and the mice in heat stress groups were challenged with a temperature of (35.5 ± 0.5) ℃ and a humidity of (60 ± 5)％ until body temperature increase up to 40 ℃ or 42 ℃ followed by recovering the surroundings temperature to normal temperature for 12 hours.The blood of medial angle of eye of mice in each group was collected for determination of plasma lipopolysaccharide (LPS),tumor necrosis factor-α (TNF-α),interleukin-6 (IL-6) levels,and diamine oxidase (DAO) activity with enzyme linked immunosorbent assay (ELISA).The level of D-lactic acid was determined with ultraviolet spectrophotometer.Then the mice in each group were sacrificed,and mesenteric lymph node (MLN),liver,spleen,lung,kidney tissues,and the blood from portal vein and caval vein were collected for colony count to observe the intestinal bacterial translocation.The ileum tissue was collected for observation of changes in histomorphology and ultrastructure of small intestine mucous membrane with microscope.Pearson linear regression analysis was used to explore the correlation between intestinal mucosal barrier dysfunction and systemic inflammatory response.Results Compared with normal control group,plasma LPS,inflammatory parameters such as TNF-α and IL-6,and gut barrier function parameters such as DAO and D-lactic acid levels as well as the rate of bacterial translocation after heat stress were significantly increased,and the differences were more obvious in 42 ℃ heat stress group [LPS (EU/L)740±50 vs.340±40,TNF-α (ng/L)148.06±36.61 vs.12.89 ± 1.67,IL-6 (ng/L)110.91 ± 9.97 vs.18.02 ± 2.20,DAO (U/L)1 760 ± 400 vs.670± 50,D-lactic acid (mg/L)9.60 ± 1.48 vs.5.08 ± 0.28,rate of bacterial translocation78.6％ (33/42) vs.9.5％ (4/42),all P ＜ 0.01].It was shown by Pearson linear regression analysis that plasma LPS,TNF-α,IL-6 were positively correlated with DAO activity (r values were 0.834,0.808,0.836,respectively) and D-lactic acid (r values were 0.811,0.811,0.800,respectively) in 42 ℃ heat stress group (all P =0.000).It was showed by microscope that the changes in histomorphology and ultrastructure changes in intestinal mucosa were found after heat stress,and was obvious in 42 ℃ heat stress group as followingvillus atrophy and falling off,infiltration of neutrophils and lymphocytes,the microvillus on the surface of mucosa cells were short and small,arranged in disorder,the tight junction between epithelial cells became widen,the mitochondrion and endoplasmic reticulum swelled obviously.Conclusion During the early stage of severe heatstroke,the damage of intestinal mucosal was obvious,and it has close correlation with systemic inflammatory response.