Effects Of Trichloroethylene On Thl7Cells In Sensitized Balb/c Mice Via Skin

Background Trichloroethylene (TCE) is a chlorinated hydrocarbon commonly usedas an industrial solvent for degreasing metals.Occupational exposure to TCE has beenlinked to the development of ODMLT（Occupational Dermatitis medicamentosa-like oftrichloroethylene) in workers and it has become a serious occupational healthissue.Multiple cell types，cytokines and inflammatory mediators have been shown to beinvolved in the regulation of immunologic and inflammatory processes in ODMLT,as anewly discovered cell，there is little study on Th17cells and its mechanism on ODMLTpatients is largely unknown.Objective To detect the intracellular expression of Th17cells,IL-17and IL-6onTCE-sensitived Balb/c mice of vary groups at different time.To investigate the role ofTh17cells and Th17-related cytokines in the formation progress of ODMLT.To providenewly evidence for the exploration of ODMLT.Methods6~8-week-old female Balb/c mice (weight:around25g) were purchased andacclimatized for a week.Animals were randomly divided into six groups,representingthe control and the treatment groups.All animals were healthy and weighedeverday.Refer to the Guinea Pig Maximization Test (GPMT) to establish TCE-inducedODMLT model,cutaneous reaction score was in judged by “The technical specificationof toxicity identification for chemicals”（The Ministry Of Health Inspection【2005】NO.272）.When the cutaneous reaction score of any animal in the traetment group≥1，it should be judged as positive reaction and in the sensitized group，then others was in non-sensitized group.At the termination of each group,blood was withdrawn from theophthalmic vein,15mm*20mm of back skin was cut and fixed with10%formaldehyde，after the skin sections were made,IL-17and IL-6expression in the skin was detected byimmunohistochemistry staining.the spleen was removed and used for the isolation ofsplenocytes,in order to detect the quality of Th17cells.Serum was isolated from theblood and stored at-80℃and IL-17、IL-6expression in serum was determined byELISA.Data are presented as mean±SD.Comparison of all groups was made with aone-way analysis of avariance ANOVA test with SPSS13.0.A P value less than0.05wasconsidered significant.Results1.Sensitizing rate:Refer to the Guinea Pig Maximization Test (GPMT) to establishTCE-sensitized DMLT model, no red spot or dropsy on skin were observed in the blankcontrol group, parts of the treatment groups observerd skin destruction,under this experimentalcondition,the sensitizing rate is36%.2.Pathologic results of skin： NO inflammation reaction such as granulocyteinfiltration and epidermal thickening was seen in skin tissue of blank controlgroup.While sensitized mice shows significant inflammation changes of the skin, thickening of theepidermis,dropsy and necrosis around the folliculus pili, a large number of neutrophils andinflammatory cells infiltration.3.Results of Th17cells in splenocytes suspension:The number of Th17cells in thesensitized2d and3d groups were obviously higher than the sensitized1d group and theblank control group, the differences between them were significantly different(P＜0.05).Compared with TCE sensitized2d and3d groups,the results of Th17cells in thesensitized7d and14d groups were much lower and the differences achieved statistical significance.4.Results of IL-17in serum:The level of IL-17in serum of1d,2d and3d sensitizedgroups were higher than that of blank control group and the results between them weresignificantly different(P＜0.05).Compared with TCE sensitized1d group,the level ofIL-17in serum were lower in TCE sensitized7d and14d groups,and the differencesbetween them was statistically significant(P＜0.05).In TCE sensitized7d and14dgroup,IL-17level in serum were lower than the TCE sensitized2d and3d groups, thedifference between them were statistically significant(P＜0.05).5.Expression of IL-17in skin tissue:Immunohistochemical study on IL-17showedsignificant(P＜0.05) higher expression of TCE sensitized1d,2d and3d groups than theblank control group, Compared with the TCE sensitized2d group,the TCEnon-sensitized2d group showed lower expression but the sensitized3d group showedhigher effects of IL-17and the results between them were statistically significant(P＜0.05). The TCE non-sensitized3d group and sensitized7d group showed lowerexpression than the sensitized3d group and the results were were statisticallysignificant(P＜0.05).Comparison between the TCE7d sensitized and non-sensitizedwere significantly different(P＜0.05).6.Results of IL-6in serum:The level of IL-6in serum of1d,2d,3d and7d sensitizedgroups were higher than that of blank control group and the results between them weresignificantly different(P＜0.05).Compared with TCE sensitized1d group,the level ofIL-6in serum were lower in TCE non-sensitized1d and7d groups but higher in TCEsensitized2d and3d groups,and the differences between them was statisticallysignificant(P＜0.05).In TCE sensitized3d,7d and14d groups,IL-6level in serum werediffereent with TCE sensitized2d group and the difference between them were statistically significant(P＜0.05),Compared with TCE sensitized3d and7d groups,theirrelated non-sensitized groups and TCE sensitized14d were lower,and the resultsbetween them were statistically significant(P＜0.05).7.Expression of IL-6in skin tissue:Immunohistochemical study on IL-6showedsignificant(P＜0.05) higher expression of TCE sensitized2d,3d and1w groups than theblank control group, Compared with the TCE sensitized1d group,the TCE sensitized3dgroup showed higher effects of IL-6and the results between them were statisticallysignificant(P＜0.05). The TCE non-sensitized2d group and sensitized14d groupshowed lower expression than the sensitized2d group and the results were werestatistically significant(P＜0.05).Compared with the TCE sensitized3d group,the TCEnon-sensitized3d group and the sensitized2w group showed lower effects of IL-6andthe results between them were statistically significant(P＜0.05).Comparison betweenthe TCE7d sensitized and non-sensitized were significantly different(P＜0.05).Conclusion：1.TCE can cause sensitive effect on Balb/c mouce with proper dose,at this experimentcondition, the sensitive rate is36%.2.The level of Th17cells and its related cytokines IL-17、IL-6showed statisticalsignificannce between sensitized and non-sensitized groups, they may participate in theformation of TCE-induced cutaneous sensitized reaction and plays an important role inODMLT.