The Effect Of Lactobacillus Acidophilus On Expression Of Chemokines RANTES And MCP-1 In Murine Intestinal Mucosa With Ulcerative Colitis

Objective:To investigate the effect of lactobacillus acidophilus on expression of chemokines RANTES and MCP-1 in murine intestinal mucosa with ulcerative colitis and its possible mechanismMethods:Seventy specific pathogen free,7-8 week-old male BALB/c mice (weight 21.0±2.0g), were randomly divided into seven groups as follows:negative control group(normal saline, NS group), positive control group(mesalazine), model control group,low-dose(106CFU/ml),moderate-dose(107CFU/ml) and high-dose (108CFU/ml) lactobacillus acidophilus groups, normal control group,(n=10/group).The normal group mice were only fed with distilled water. Experimental group was induced by drinking 2.5% dextran sulfate sodium (DSS, MW:36000-50000) freely for 7 consecutive days. Before two days,each experimental group of the mice was given normal saline(NS),mesalazine(30.25mg/ml),low-dose(1.0×106CFU/ml),moderate-dose(1.0×107CFU/ml) and high-dose(1.0×108CFU/ml) lactobacillus acidophilus respectively. The model group was given empty needle to insert stomach.To observe each mouse's genenal state of health on experiment procese,daily weight,stool trait and occult blood of all the animals were recorded. After 8 days, the mice of each group were sacrificed. Isolated the whole colon and measure lenth of integrity colon. the whole colon was washed cleanly by cold normal saline, The distal colon,middle colon and proximal colon were obtained respectively. The distal colon specimens for maldehyde fixed, were embedded in paraffin and stained with hematoxylin-eosin (H&E), and the conditions of the mice were observed; The remaining specimens were preserved at-70℃for reverse transcription polymerase chain reaction (RT-PCR). The following indices were used for evaluation:disease activity index (DAI), colon length, histological injury scores;immunohistoch-emistry, and reverse transcription-polymerase chain reaction (RT-PCR) were used to test the content of chemokines RANTES and MCP-1 protein and the level of chemokines RANTES MCP-1 and STAT1 mRNA respectively.Results:1.The genenal conditions and DAI scores in mice were significantly improved in Lactobacillus treatment group and mesalazine treatment group, compared with that in model group and negative group of mice(p<0.05).Compared with model group, the colon length of lactobacillus treatment (high-dose) group was statistically significant(p<0.05).Compared with normal group, it had no statistical significance(p>0.05).2. The histological injury scores in UC mice were higher than normal group's(p<0.05),the scores of lactobacillus treatment group were reduced comparatively, compared with that in model group and negative group of mice(p<0.05), but there were no significance, compared with that in the mesalazine group(p>0.05).3. The protein expression of chemokines RANTES and MCP-1 in UC mice were higher than normal group's(p<0.05), the protein expression of chemokines RANTES and MCP-1 were decreased in Lactobacillus treatment group and mesalazine group, especially the high-dose group(p<0.05). The trends of RANTES and MCP-1 mRNA expression in colonic mucosa of UC mice was consistent with that of the protein expression.The mRNA expression of high-dose lactobacillus group was much better than that low-dose group (p<0.05)4. The mRNA expression of STAT1 was also decreased in lactobacillus treatment group and mesalazine group;compared with lactobacillus treatment group, the inhibition of STATl activation in mesalazine treatment group was better (P<0.05)Conclusion:1. Lactobacillus was effective to treatment of DSS-induced UC in mice, and the effect was related to its dose.2. Lactobacillus had therapeutic effects for mice with acute UC mice. The mechanism may be possibly related to the inhibition of transcription factor STAT1 activation, which in turn leads to lowered expressionof chemokines RANTES and MCP-1 in colonic mucosa.