ObjectiveTo investigate the effect of interleukin (IL)-23 receptor (IL-23R) overexpression on the balance of T helper 17 (Th17 cells)/regulatory T cells (Treg cells) in experimental autoimmune uveitis (EAU) mice. MethodsTwelve 8-week-old female C57BL/6J mice were randomly divided into LV-Ctrl group and LV-IL-23R group, with 6 mice in each group. Two groups of mice were injected with LV-Ctrl and LV-IL-23Rlentiviruses through the tail vein, respectively; 7 days after injection, the EAU mouse model was established by active immunization with vitamin A-binding protein 1-20 between photoreceptors. Starting from 13 days after immunization, the fundus of the mice was observed by indirect ophthalmoscopy every 2 days and clinical scores were performed; 30 days after immunization, hematoxylin-eosin staining was used to observe the histopathological changes of mouse retina. The levels of IL-17 in serum of the two groups of mice were detected by enzyme-linked immunosorbent assay; the proportion of Th17 cells and Treg cells was detected by flow cytometry. The relative mRNA expression of IL-23R, IL-17, retinoic acid-related orphan receptor γt (RORγt), IL-10 and forkhead transcripyion factor p3 (Foxp3) were detected by real-time quantitative polymerase chain reaction. Comparisons between groups were performed using repeated measures analysis of variance, independent samples Mann-Whitney U test, and independent samples t test. ResultsCompared with the LV-Ctrlgroup, the retinal inflammatory reaction of the LV-IL-23R group was more severe. At 13 days after immunization, there was no significant difference in fundus inflammation scores between LV-IL-23R group and LV-Ctrl group (t=－2.001, P=0.058); 15-29 days after immunization. The fundus inflammation scores of LV-IL-23Rgroup were higher than those of LV-Ctrl group, and the difference was statistically significant (t=－4.429, －6.578, －7.768, －10.183, －6.325, －7.304, －4.841, －6.872; P＜0.001). Histopathological examination showed that the infiltration of inflammatory cells in the fundus increased, the retinal structure was damaged more seriously, and the histopathological score was significantly increased, and the difference was statistically significant (t=－4.339, P=0.001). Compared with the LV-Ctrl group, the relative expression of IL-23RmRNA in the spleen of the LV-IL-23R group was significantly increased, and the difference was statistically significant (Z=2.087, P=0.037). The relative expression of IL-17 and RORγt mRNA increased, while the relative expression of IL-10 and Foxp3 mRNA decreased, and the differences were statistically significant (t=－6.313,－5.922, 4.844, 7.572; P=0.003, 0.004, 0.008, 0.002). Compared with the LV-Ctrl group, the level of IL-17 in the serum of the mice in the LV-IL-23R group was significantly increased, and the difference was statistically significant (t=－5.423, P=0.002); the proportion of Th17 cells in the spleen and lymph nodes was significantly increased, whereas, the proportion of Treg cells was significantly reduced, and the difference was statistically significant (t=－4.290, 3.700; P=0.002, 0.006). ConclusionIL-23R overexpression can promote Th17/Treg imbalance in EAU mice, and aggravate the clinical and pathological manifestations of EAU.
Objective To investigate the effect of peptidoglycan (PGN) on the secretion of pro-inflammatory cytokines by dendritic cells (DCs) and the regulation of T helper 17 (Th17) responses in experimental autoimmune uveitis. Methods Bone marrow cells from naive mice were cultured with granulocyte macrophage-colony-stimulating factor and interleukin (IL)-4 to induce DCs. DCs cultured for six days were randomly divided into two groups: PGNtreated group and control group. The DCs in PGNtreated group were stimulated with PGN and the same volume of phosphate buffered saline was added to the DCs as control group. The relative mRNA expression levels of IL-23, tumor necrotic factor alpha; (TNF-alpha;), IL-6,IL-1beta;were measured by real-time reverse transcriptase polymerase chain reaction (RT-PCR). Peptide fragment of interphotoreceptor retinoidbinding protein (IRBP1-20)specific T cells, which were isolated from the spleen and draining lymph nodes of C57BL/6 mice immunized with IRBP1-20 peptide fragments 13 days earlier, were co-cultured with PGN-treated or untreated DCs, respectively. Total RNA from T cells cocultured for two days were isolated and the relative expression of retinoic acid receptor-related orphan receptor gamma;t (ROR-gamma;t), IL-17, T-box expression in T cells (T-bet), interferon gamma; (IFN-gamma;) mRNA were detected by realtime RT-PCR. On the second, the fifth and the seventh day, the cocultured T cells were analyzed by flow cytometry to detect the percentages of IFN-gamma;, IL-17 positive cells. Results The real-time RT-PCR results revealed that the level of IL-23, IL-1beta;, IL-6, TNF-alpha; mRNA from PGNstimulated DCs were significantly increased compared to the control group (t=-14.363, -5.627, -3.85, -28.151; P＜0.05). The level of RORgamma;t, IL-17 mRNA from the T cells cocultured with PGN-stimulated DCs were greatly increased compared with the control group (t=-5.601, -19.76；P＜0.05). However, the level of T-bet, IFN-gamma; mRNA from the T cells cocultured with PGNstimulated DCs were significantly decreased compared with the control group (t=4.717, 11.207; P＜0.05). Data of flow cytometry showed that at two days, five days, seven days after cocultured with PGN-treated DCs, the percentages of IL-17 positive T cells were increased compared to the control group (t=-2.944, -3.03, -4.81; P＜0.05), and the percentages of IFN-gamma; positive T cells had no remarkable change (t=-1.25, -0.18, -2.16; P＞0.05). Conclusion PGN can promote the secretion of Th17-related cytokines by DCs, which favors proliferation and differentiation of Th17 in experimental autoimmune uveitis.