Activation of the aryl hydrocarbon receptor reduces the number of precursor and effector T cells,but preserves thymic CD4CD25Foxp3 regulatory T cells

Aryl hydrocarbon receptor (AhR) activation suppresses immune responses, including allergic sensitization, by increasing the percentage of regulatory (Treg) cells. Furthermore, AhR activation is known to affect thymic precursor T cells. However, the effect of AhR activation on intrathymic CD4⁺CD25⁺Foxp3⁺ Treg cells is unknown. Therefore, we investigated the effect of AhR activation on the percentage and number of CD4⁺CD25⁺Foxp3⁺ Treg cells during allergic sensitization in relevant immunological organs.     

CD4＋CD25＋Treg调节性T细胞及其细胞因子在大鼠动脉粥样硬化中改变的研究

目的 研究CD4＋ CD25＋ Treg调节性T细胞及其分泌的细胞因子在大鼠动脉粥样硬化中的改变.方法 制备动脉粥样硬化模型,取雄性SD大鼠30只,随机分为正常饮食组（A组）10只及高脂饮食组（B组）20只,高脂饮食组再分为对照组与干预组各10只,干预组高脂饲料喂养前腹腔注射抗CD25＋单克隆抗体250μg,A组及对照组腹腔注射大鼠IgG抗体（250μg）,高脂饮食组定期用维生素D腹腔注射.上述各组喂养3个月后,各组随机抽取6只大鼠通过流式细胞学技术检测CD4＋ CD25 ＋Treg细胞及Foxp3＋的表达、检测炎症因子IL-10,IL-1β水平,处死各组大鼠做病理切片.结果 3组中干预组CD4＋ CD25＋ Treg细胞及Foxp3＋表达下降最明显,IL-10水平明显下降,IL-1β水平明显升高,A组CD4＋ CD25＋ Treg细胞及Foxp3＋表达最高,IL-10水平亦最高,IL-1β水平最低.而对照组在干预组及A组之间.结论 动脉粥样硬化形成中CD4＋ CD25＋ Treg调节性T细胞及其分泌的细胞因子受到抑制,而不是CD4＋ CD25＋ Treg调节性T细胞分泌的因子却显著升高,考虑动脉粥样硬化的形成有免疫反应参与.     

The effects of Foxp3-expressing regulatory T cells expanded with CD28 superagonist antibody in DSS-induced mice colitis

Regulatory T (Treg) cells play an important role in the pathogenesis of inflammatory bowel disease (IBD). In the present study, we found that a superagonistic CD28-specific monoclonal antibody (supCD28mAb, D665) could preferentially stimulate expansion of CD4+Foxp3+ Treg cells. Foxp3(EGFP) mice were orally administrated with 3.5% DSS for 5days, and intraperitoneally injected supCD28mAb 1mg/mice in treated group. All of the mice were sacrificed on day 8, and both clinical and histological parameters showed that the severity of colitis was significantly reduced in treated group compared to controls. In treated group, the proportion of CD103, CD152 and CD62L expression on Foxp3+Treg cells in the spleen and mesenteric lymph node were higher than controls. Furthermore, qRT-PCR analysis showed that expression of anti-inflammatory cytokines such as IL-10, TGF-β was significantly increased in treated group. Taken together, our data demonstrated that supCD28mAb targets CD4+Foxp3+Treg cells expansion in vivo, maintains and enhances their regulatory functions, to reduce the damage of colon in dextran sulfate sodium (DSS)-induced mouse colitis by secreting a large amount of IL-10. It represents a major advance towards the therapeutic use of polyclonally activated Treg cells as cellular therapy for treatment of IBD.     

3, 3′-diindolylmethane alleviates steatosis and the progression of NASH partly through shifting the imbalance of Treg/Th17 cells to Treg dominance

This study was designed to discuss the effects of 3, 3′-diindolylmethane (DIM) on methionine–choline-deficient (MCD)-diet induced mouse nonalcoholic steatohepatitis (NASH) and the potential mechanisms. NASH mice were administrated with or without DIM at different concentrations for 8 weeks. Both the in-vivo and in-vitro effects of DIM on Treg/Th17 imbalance during NASH progression were analyzed. The in-vivo blocking of CD25 or IL-17 was performed to respectively deplete respective function of Treg or Th17 subset. Besides, with the assistance of AhR antagonist CH223191 and anti-TLR4 neutralizing antibody, we designed the in-vitro DIM-incubation experiments to discuss the roles of aryl hydrocarbon receptor (AhR) (CYP1A1, CYP1B1) and toll-like receptor 4 (TLR4) on DIM's effects when shifting Treg/Th17 imbalance. Notably, in NASH mouse models, DIM alleviated hepatic steatosis and inflammation, and shifted the Treg/Th17 imbalance from MCD diet-induced Th17 dominance to Treg dominance. In-vitro, DIM not only significantly up-regulated the mRNAs of Foxp3 (Treg-specific) in purified spleen CD4⁺ T cells, but also enhanced the immunosuppressive function of these Treg cells. Besides, DIM significantly up-regulated the proteins of CYP1A1 and CYP1B1 whereas down-regulated those of TLR4 on CD4⁺ T cells from MCD-diet mice. Moreover, blocking AhR attenuated while blocking TLR4 enhanced the effects of DIM when regulating Treg/Th17 imbalance. Conclusively, DIM could be used as a potential therapeutic candidate to treat NASH based on its dramatic induction of Treg dominance to alleviate intra-hepatic inflammation, suggesting us a clue that the dietary cruciferous vegetables (containing abundant DIM) might exist as a protective factor for patients with NASH-related liver diseases.     

Th17/Treg平衡在类风湿关节炎中作用的研究进展

类风湿性关节炎(rheumatoid arthritis,RA)是一种以慢性多关节滑膜炎为主要特征的自身免疫性疾病。虽然目前对于RA的确切发病机制尚不明确,但一般认为和T细胞相关。最近研究发现调节性T细胞(regulatory T cell,Treg)和Th17细胞在RA的发生发展中发挥重要作用。Th17细胞能够分泌促炎症因子IL-17,通过诱导基质金属蛋白酶(ma-trix metallo proteinases,MMPs)和破骨细胞生成,促进骨滑膜炎症、骨和关节损伤;而Treg则通过释放抑制性细胞因子IL-10和TGF-β发挥免疫效应,调控RA中的炎症性免疫应答过程。单独TGF-β作用下诱导初始T细胞分化为Treg,而在TGF-β和IL-6共同作用下诱导初始T细胞分化为Th17细胞,因此,Th17和Treg细胞在特定的细胞因子微环境下可以相互转化。调节Th17/Treg之间的平衡可能成为治疗RA的新方法。该文将对Th17/Treg平衡在RA发生发展中的调节作用作一综述。     

Unexpected modulation of recall B and T cell responses after immunization with rotavirus-like particles in the presence of LT-R192G

LT-R192G, a mutant of the thermolabile enterotoxin of E. coli, is a potent adjuvant of immunization. Immune responses are generally analyzed at the end of protocols including at least 2 administrations, but rarely after a prime. To investigate this point, we compared B and T cell responses in mice after one and two intrarectal immunizations with 2/6 rotavirus-like particles (2/6-VLP) and LT-R192G. After a boost, we found, an unexpected lower B cell expansion measured by flow cytometry, despite a secondary antibody response. We then analyzed CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) and CD4(+)CD25(+)Foxp3(-) helper T cells after in vitro (re)stimulation of mesenteric lymph node cells with the antigen (2/6-VLP), the adjuvant (LT-R192G) or both. 2/6-VLP did not activate CD4(+)CD25(+)Foxp3(-) nor Foxp3(+) T cells from non-immunized and 2/6-VLP immunized mice, whereas they did activate both subsets from mice immunized with 2/6-VLP in the presence of adjuvant. LT-R192G dramatically decreased CD4(+)CD25(+)Foxp3(+) T cells from non-immunized and 2/6-VLP immunized mice but not from mice immunized with 2/6-VLP and adjuvant. Moreover, in this case, LT-R192G increased Foxp3 expression on CD4(+)CD25(+)Foxp3(+) cells, suggesting specific Treg activation during the recall. Finally, when both 2/6-VLP and LT-R192G were used for restimulation, LT-R192G clearly suppressed both 2/6-VLP-specific CD4(+)CD25(+)Foxp3(-) and Foxp3(+) T cells. All together, these results suggest that LT-R192G exerts different effects on CD4(+)CD25(+)Foxp3(+) T cells, depending on a first or a second contact. The unexpected immunomodulation observed during the recall should be considered in designing vaccination protocols.