RÉSUMÉ
BackgroundStudies determined that Th17 cells are important inflammatory cell group in experimental autoimmune uveoretinitis ( EAU ).Interleukin-17 ( IL-17 ),as a marker of Th17,is involved in the occurrence and development of EAU.Mesenchymal stem cells (MSCs) play an immunomodulatory role,mainly by inhibiting the expression of Th17 in a variety of self-autoimmune disease.This is one of the current research focuses.ObjectiveThe present study was to investigate the therapeutic effect of MSCs in EAU and their impact on IL-17 expression in the retina.MethodsMSCs were isolated from the bone marrow of the femurs from 10 SPF Wistar rats and cultured and passaged.The third to fifth generations of cells were used in this experiment.EAU models were induced in 48 6-8 week-old SPF Lewis rats by subcutaneous injection of interphotoreceptor retinoid binding protein (IRBP) R16 peptide emulsified in adjuvant.EAU rats were randomly assigned to the model control group and the MSCs group.MSCs suspension (5×106) of 1 ml was injected via the rat tail vein once a day for 3 consecutive days after immunization,and the same amount of PBS was injected in the model control group in the same manner.Six matched normal Lewis rats were used as the normal control group.The inflammatory response was clinically examined under the slit lamp biomicroscope daily,and the histopathological changes of the retina were examined by hematoxylin and eosin staining on days 9,12,15 and 20.The clinical and histopathological scoring was performed according to the Caspi criteria.Expression of the IL-17 protein in the retina was detected by immunohistochemistry on 9,12,15 and 20days following molding.The use of the animals complied with the Regulations for the Administration of Affairs Concerning Experimental Animals by Tianjin Municipality Science and Technology Commission.Results MSCs showed the fusiform in shape and vortex-like growth.Flow cytometry verified that presented the positive expression for CD29 and CD44 but absent expression for CD45 and CD34.The scores of the anterior segment were significantly lower ( U=2.815,P =0.005 ; U =2.768,P =0.006 ; U =2.900,P =0.004 ; U =2.855,P =0.004 ),and the retinal inflammation scores were lower in the MSCs group than the model control group at various time points ( U =2.345,P =0.019 ; U =2.559,P =0.011 ; U =2.166,P =0.030 ; U =2.373,P =0.018 ).Im mnunochemistry showed that the expressions levels of the IL-17 protein (A value) in the rat retina were 26.47±5.68,77.78± 9.65,47.02±6.68 and 26.59±5.94 in the MSCs group on days 9,12,15 and 20,and those in the control group were 45.34±4.63,105.95± 10.74,64.11 ±9.76 and 37.02±6.51,showing a significant reduction ( t =6.305,P =0.000 ; t =4.799,P =0.001 ; t=3.540,P=0.005;t=2.900,P=0.016). ConclusionsMSCs can inhibit the aggravation of EAU and suppress the expression of IL-17 in ocular tissue.
RÉSUMÉ
Background Studies determined that rapamycin has not only the antibiosis but also suppressing the auto-immunology.The treating effect of rapamycin on experimental autoimmune uveoretinitis (EAU) is still concerned.Objective This work was to investigate the therapeutic effect of rapamycin on EAU and study the effect on the expression of inflammatory cytokines which were secreted by T lymphocyte subgroup in EAU.Methods EAU was induced in 20 SPF male Lewis rats by subcutaneous injection of interphotoreceptor retinoid binding protein (IRBP) R16 peptide emulsified in adjuvant.The rats were randomized into model control group and rapamycin injection group and 10 rats for each group.The rapamycin of 0.2 mg/( kg · d) 0.4 ml was intraperitoneally injected for the consecutive 7 days immediately after modeling,and the equal volume of normal saline solution was used at the same fashion in the model control group and 5 normal matched rats( normal control group).The ocular manifestation of the rats were examined under the slit lamp regularly.The retinal sections of the rats were prepared in the 14 days after modeling for the histopathological examination with hematoxylin and eosin staining.The ocular signs of inflammation and histopathological severity were scored based on the criteria of Caspi.Expression of interferon-γ (IFN-γ) and interleukin-17 (IL-17) in rat retinas were detected by immunohistochemistry.This experiment followed the Regulation for the Administration of Affair Concerning Experimental Animals by Tianjin Municipal Government.Results The scores of ocular signs elevated gradually from 6 through 12 days after modeling and slowly declined after that in the model control group.A same tendency was seen in the rapamycin injection group.The significant differences were seen in the scores of ocular signs between the two groups from 6 to 14 days( P＜0.01 ).The disorder of retinal structure and infiltration of inflammatory cells were seen in the model control group,but the retina layers were normal in the rapamycin injection group.The pathological score was evidently declined in the rapamycin injection group ( 0.90 ± 0.45 ) in comparison with model control group( 3.30±0.48 ) ( t =16.541,P＜0.01 ).The expressions of the IFN-γ and IL-17 in retina located in the outer nuclear layer,inner nuclear layer,internal plexiform layer and retinal ganglion cell layer with the weakened levels(A values) in rapamycin injection group compared with model control group,showing a considerably difference between them ( IFN-γ:21.16±4.23 vs 62.14 ±7.32; IL-17:49.86±6.59 vs 124.85 ±6.33 )(q=33.334,q=56.923,P＜0.01 ).Conclusions Rapamycin down-regulates the expressions of IFN-γ and IL-17 in retina and further eliminates the inflammatory response in the rat with EAU by the suppression of Th1 and Th17 cells function in EAU.