Deficiency of ß-Arrestin 2 in Dendritic Cells Contributes to Autoimmune Diseases.

Altered migration and immune responses of dendritic cells (DCs) lead to inflammatory and autoimmune diseases. Our studies demonstrated that ß-arrestin 2 deficiency promoted migration and cytokine production of mouse bone marrow-derived DCs. We further found that ß-arrestin 2 directly interacted with Zbtb46, a DC-specific transcription factor. What's more, our results suggested that the interaction between ß-arrestin 2 and Zbtb46 might negatively regulate DC migration. Using RNA sequencing, we indicated that genes CD74, NR4A1, and ZFP36 might be the target genes regulated by the interaction between ß-arrestin 2 and Zbtb46. Mice with selective deficiency of ß-arrestin 2 in DCs developed severer experimental autoimmune encephalomyelitis with more DC infiltration in the CNS and increased IL-6 in serum. In the systemic lupus erythematosus mice model, Arrb2fl/fl Itgax-cre+ mice were prone to exacerbation of lupus nephritis with a higher level of IL-6 and DC accumulation. Taken together, our study identified ß-arrestin 2 as a new regulator of DC migration and immune properties, providing new insights into the mechanisms underlying the development of autoimmune disease.

Critical Role of P2Y12 Receptor in Regulation of Th17 Differentiation and Experimental Autoimmune Encephalomyelitis Pathogenesis.

Adenosine 5'-diphosphate is a key endogenous cell-signaling molecule that can activate P2 purinergic receptor family members. ADP-P2Y signaling is reported to be associated with inflammation, but its function in T cell differentiation and autoimmune diseases pathogenesis is unclear. In this study, we found that the P2Y12 receptor was upregulated in the peripheral immune tissues of experimental autoimmune encephalomyelitis (EAE) mice. Deficiency of P2Y12 led to a reduced peak severity and cumulative disease score in EAE mice, followed by a dramatic reduction of leukocyte infiltration and less extensive demyelination. The percentage of Th17, one of the main pathogenic T cells in EAE, was sharply decreased in P2Y12 knockout mice, accompanied by decreased IL-17A production and a low mRNA level of Th17-related genes. In vitro culture assay further verified that P2Y12 directly regulated Th17 differentiation. More interestingly, clopidogrel and ticagrelor, two P2Y12-specific antagonists, effectively alleviated the disease severity of EAE and inhibited Th17 differentiation both in vivo and in vitro. Further study demonstrated that blocking the P2Y12 receptor also ameliorated the symptoms of 2,4,6-trinitrobenzenesulfonic acid-induced colitis and multiple low-dose streptozocin-induced type 1 diabetes. Our findings not only revealed the critical role of P2Y12 in Th17 differentiation and EAE pathogenesis, but also suggested the promising potential of P2Y12 antagonists in the treatment of autoimmune diseases.

Deficiency of the G protein Gαq ameliorates experimental autoimmune encephalomyelitis with impaired DC-derived IL-6 production and Th17 differentiation.

Many G protein-coupled receptors (GPCRs) are reported to be involved in the pathogenesis of multiple sclerosis (MS), and ~40% of all identified GPCRs rely on the Gαq/11 G protein family to stimulate inositol lipid signaling. However, the function of Gα subunits in MS pathogenesis is still unknown. In this study, we attempted to determine the role of Gαq in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), a well-known mouse model of MS. We discovered that compared with wild-type mice, Gαq-knockout mice exhibited less severe EAE symptoms, with lower clinical scores, reduced leukocyte infiltration and less extensive demyelination. Moreover, a significantly lower percentage of Th17 cells, one of the key players in MS pathogenesis, was observed in Gαq-knockout EAE mice. Studies in vitro demonstrated that deficiency of Gαq in CD4+ T cells directly impaired Th17 differentiation. In addition, deficiency of Gαq significantly impaired DC-derived IL-6 production, thus inhibiting Th17 differentiation and the Gαq-PLCß-PKC and Gαq-MAPKs signaling pathways involved in the reduced IL-6 production by DCs. In summary, our data highlighted the critical role of Gαq in regulating Th17 differentiation and MS pathogenesis.

The Spatio-Temporal Expression Profiles of CD4 + T Cell Differentiation and Function-Related Genes During EAE Pathogenesis.

Multiple sclerosis is a CD4+ T cell-mediated autoimmune disease of the central nervous system. The unbalance of the cytokines and transcription factors critical for CD4+ T cell differentiation and function is probably the main reason that causes MS. We detected the mRNA expression changes of key cytokines and transcription factors which are critical for Th1, Th2, Th17, and Treg cell differentiation and function in different tissues during EAE pathogenesis. We fund that each gene not only has its own featured expression changes, but also has interaction with one another, which composes a network of immunity. Understanding the roles of key cytokines and transcription factors in these processes will help to understand disease pathogenesis and supply indications for disease therapy.

Discovery of BVDU as a promising Drug for autoimmune diseases Therapy by Dendritic-cell-based functional screening.

Dendritic cells (DCs) play a critical role in the pathogenesis of autoimmune diseases including multiple sclerosis, and targeting DCs' cytokines production is an important strategy for autoimmune diseases treatment. By establishing a high-throughput screening system, we analyzed LOPAC drug library to identify drugs that control the secretion of IL-6 by DCs, we selected the most likely candidate drug, BVDU, and found that it affected not only IL-6 production, but also that of IL-12, IL-1ß during the DCs differentiation and maturation. The mechanism studies showed that BVDU treatment restricted the phosphorylation of MAP kinase, which played an important role in DC cytokine production. We further assessed the in vivo therapeutic potentials of BVDU on mouse models including EAE and STZ-induced T1D, and found that BVDU treated EAE mice exhibited significantly lower EAE clinical scores, decreased leukocyte infiltration in central nervous system lesions, and reduced demyelination. As in T1D mice, BVDU treatment also showed promising therapeutic effects based on both alleviated disease symptoms and tissue pathogenesis. More interestingly, the modulating effect of BVDU on IL-6 production was further verified in human primary DCs. The above data supported the promising application of our screen model, and also the potential of BVDU for autoimmune diseases therapy.