狗是重要的伴侣动物,也是人类疾病的模型物种。鉴于T细胞在免疫反应中的核心作用,基本了解犬常规T细胞受体(TCR)αβ+T细胞,包括CD4+单阳性(sp)辅助T细胞(Th)和CD8α+sp细胞毒性T细胞亚群,是可用的。然而,犬非常规TCRαβCD4CD8α双阳性(dp)和TCRαβCD4-CD8α-双阴性(dn)T细胞的表征有限。在这项研究中,我们对犬dp和dnT细胞进行了综合分析,并与传统的dp和dnT细胞进行了比较.将健康犬外周血中的TCRαβ+T细胞根据其CD4/CD8α表型分为四个群体(即CD4+sp,CD8α+sp,dp,和dn)和选定的表面标记,通过RT-qPCR分析离体和体外刺激后的转录因子和效应分子。确定了犬dpT细胞的新特征,将先前表征的Th1样表型扩展为Th17样和Th2样特性。总的来说,各种Th细胞相关细胞因子的mRNA表达(即IFNG,IL17A,刺激后dpT细胞中的IL4,IL13)突出了它们的通用免疫潜力。此外,我们证明CD4-CD8α-dn表型在体外刺激期间是稳定的。引人注目的是,发现dnT细胞在刺激后表达最高mRNA水平的2型效应细胞因子(IL4、IL5和IL13)。在蛋白质水平上证实了它们产生IL-4的强能力。在刺激时,非常规dn中产生IL-4的细胞百分比甚至高于常规CD4sp群体。IL1RL1(编码IL-33Rα)的组成型转录进一步支持dnT细胞群内的Th2样性质。这些数据表明dnT细胞在2型免疫中的作用。此外,dnT细胞转录编码共抑制性受体CTLA-4的基因并产生抑制性细胞因子IL-10的高潜力表明该群体具有推定的免疫抑制能力。总之,这项研究揭示了犬非常规T细胞的重要新方面,为进一步研究其效应和/或调节功能提供了基础,以阐明其在健康和疾病中的作用.
The dog is an important companion animal and also serves as model species for human diseases. Given the central role of T cells in immune responses, a basic understanding of canine conventional T cell receptor (TCR)αβ+ T cells, comprising CD4+ single-positive (sp) T helper (Th) and CD8α+ sp cytotoxic T cell subsets, is available. However, characterization of canine non-conventional TCRαβ+ CD4+CD8α+ double-positive (dp) and TCRαβ+ CD4-CD8α- double-negative (dn) T cells is limited. In this study, we performed a comprehensive analysis of canine dp and dn T cells in comparison with their conventional counterparts. TCRαβ+ T cells from peripheral blood of healthy dogs were sorted according to their CD4/CD8α phenotype into four populations (i.e. CD4+ sp, CD8α+ sp, dp, and dn) and selected surface markers, transcription factors and effector molecules were analyzed ex vivo and after in vitro stimulation by RT-qPCR. Novel characteristics of canine dp T cells were identified, expanding the previously characterized Th1-like phenotype to Th17-like and Th2-like properties. Overall, mRNA expression of various Th cell-associated cytokines (i.e. IFNG, IL17A, IL4, IL13) in dp T cells upon stimulation highlights their versatile immunological potential. Furthermore, we demonstrated that the CD4-CD8α- dn phenotype is stable during in vitro stimulation. Strikingly, dn T cells were found to express highest mRNA levels of type 2 effector cytokines (IL4, IL5, and IL13) upon stimulation. Their strong ability to produce IL-4 was confirmed at the protein level. Upon stimulation, the percentage of IL-4-producing cells was even higher in the non-conventional dn than in the conventional CD4+ sp population. Constitutive transcription of IL1RL1 (encoding IL-33Rα) further supports Th2-like properties within the dn T cell population. These data point to a role of dn T cells in type 2 immunity. In addition, the high potential of dn T cells to transcribe the gene encoding the co-inhibitory receptor CTLA-4 and to produce the inhibitory cytokine IL-10 indicates putative immunosuppressive capacity of this population. In summary, this study reveals important novel aspects of canine non-conventional T cells providing the basis for further studies on their effector and/or regulatory functions to elucidate their role in health and disease.