It is well known that dendritic cells (DCs) play a pivotal role in triggering self-specific responses. Conversely, tolerogenic DCs (tolDCs), a specialized subset, induce tolerance and negatively regulate autoreactive responses. Tofacitinib, a Janus kinase inhibitor developed by Pfizer for treatment of rheumatoid arthritis, is probable to be a promising candidate for inducing tolDCs. The aims of this study were to evaluate the effectiveness of tolDCs induced by tofacitinib in a myelin oligodendrocyte glycoprotein- (MOG-) specific experimental autoimmune encephalomyelitis (EAE) model and to investigate their effects on Th17/Treg balance in the animal model of multiple sclerosis (MS). Our results revealed that tofacitinib-treated DCs maintained a steady semimature phenotype with a low level of proinflammatory cytokines and costimulatory molecules. DCs treated by tofacitinib also induced antigen-specific T cells hyporesponsiveness in a concentration-dependent manner. Upon intravenous injection into EAE mice, MOG pulsed tolDCs significantly dampened disease activity, and adoptive cell therapy (ACT) disturbed Th17/Treg balance with a remarkable decrease of Th1/Th17 cells and an increase in regulatory T cells (Tregs). Overall, DCs modified by tofacitinib exhibited a typical tolerogenic phenotype, and the antigen-specific tolDCs may represent a new avenue of research for the development of future clinical treatments for MS.

Toll-like receptor 3 (TLR3) is a sensor of endogenous cell necrosis during the process of acute inflammation. Interleukin (IL)-1 receptor antagonist (IL-1Ra) is an anti-inflammatory cytokine and can negatively regulate the pathogenesis of inflammation. However, whether and how activation of TLR3 can regulate IL-1Ra expression has not been clarified. Here, we show that poly(I:C) induces IL-1Ra expression in primarily cultured human fibroblast-like synoviocytes and other types of cells. Induction of IL-1Ra by poly(I:C) was dependent on TLR3, but was independent of melanoma differentiation-­associated protein 5 or retinoic acid-inducible gene I. Interferon regulatory factor 3 (IRF3) directly binds to the IL-1Ra promoter and promotes IL-1Ra expression in response to poly(I:C) stimulation. Induction of IL-1Ra by poly(I:C) was abolished by the inhibition of the NF-κB signaling, attenuated by the inhibition of the PI3K-Akt signaling, enhanced by inhibition of the ERK1/2 or MSK1/2 activation, but was independent of the p38 MAPK signaling. Treatment with poly(I:C) or Sendai virus elevated the levels of serum IL-1Ra in wild-type, but not in TLR3^–/– or IRF3^–/– mice. Our findings may provide new insights into the intrinsic anti-inflammatory function of TLR3 and double-stranded RNA-induced IL-Ra expression by TLR3 and its regulation.

BD750, a novel JAK3/STAT5 inhibitor, can inhibit T cell proliferation. This study aims to evaluate whether BD750 can induce tolerogenic dendritic cells (tolDC) and their function in experimental autoimmune encephalitis (EAE) in mice. Following BD750 treatment, lipopolysaccharide (LPS)-induced maturation of DCs, allogeneic T cell proliferation, Th1 and Th17 cell functional differentiation, and STAT5 and AKT activation were determined. The effect of tolDC loaded with antigen peptide on the development and severity of EAE and splenic Th1 and Th17 cell responses was determined. In comparison with LPS-induced mature DCs (mDCs), BD750 treatment induced tolDC with lower expression levels of costimulatory molecules and proinflammatory cytokines and lower levels of STAT5 phosphorylation. TolDC inhibited allogeneic T cell proliferation and reduced Th1 and Th17 responses. Adoptive transfer of tolDC loaded with myelin oligodendrocyte glycoprotein35-55 inhibited the development and severity of EAE in mice, accompanied by reduced numbers of inflammatory infiltrates and decreased levels of demyelination in the spinal cord tissues. In addition, treatment with tolDC loaded with antigen peptide also significantly reduced the frequency of splenic Th1 and Th17 cells in EAE mice. The effects of tolDC were similar to that of JAK/STAT inhibitor CP690550-treated DCs. In conclusion, treatment with BD750 induced tolDC that inhibited proinflammatory T cell immunity in vitro and in vivo. BD750 and tolDC may be valuable for development of new therapies for EAE and other autoimmune diseases.

Three new 11-hydroxyburnamine (1) and rauvoyunnanines A–B (2–3), and fourteen known (4–17) monoterpenoid indole alkaloids were isolated from the total alkaloids extract of Rauvolfia yunnanensis, which exhibited promising immunosuppressive activity on T cell proliferation in preliminary screening. Their structures were determined by analysis of high-resolution electrospray ionization mass (HRESIMS), ultraviolet (UV) and nuclear magnetic resonance (NMR) data, and by comparison with the literature. All the alkaloids were evaluated for inhibitory activity on T cell proliferation. Among them, one new compound (1) and reserpine (6) exhibited moderate immunosuppressive activity, with IC₅₀ values of 5.9 μM and 5.0 μM, respectively.

Background and Purpose: Immunosuppressive drugs have shown great promise in treating autoimmune diseases in recent years. A series of novel oxazole derivatives were screened for their immunosuppressive activity. PO‐322 [1H‐indole‐2,3‐dione 3‐(1,3‐benzoxazol‐2‐ylhydrazone)] was identified as the most effective of these compounds. Here, we have investigated the mechanism(s) underlying the inhibition of T‐cell proliferation in vitro by PO‐322, as well as its effects on the delayed‐type hypersensitivity (DTH) response and imiquimod‐induced dermatitis in vivo.Experimental Approach: T‐cell proliferation and apoptosis were analysed with flow cytometry. Cell viability was assessed with a CCK‐8 assay. Protein kinase activity was assessed by SelectScreen Kinase Profiling Services. The phosphorylation of signal‐regulated molecules was measured by Western blot. Cytokine levels were determined by elisa. The effect of PO‐322 on DTH and imiquimod‐induced dermatitis was evaluated in BALB/c mice.Key Results: PO‐322 inhibited human T‐cell proliferation with anti‐CD3/anti‐CD28 mAbs or alloantigen without significant cytotoxicity. Importantly, PO‐322 was a selective inhibitor of the serum‐ and glucocorticoid‐regulated kinase 1 (SGK1) and decreased NDRG1 phosphorylation but not p70S6K, STAT5, Akt, or ERK1/2 phosphorylation. Furthermore, PO‐322 inhibited IFN‐γ, IL‐6, and IL‐17 expression but not IL‐10 expression. Finally, treatment with PO‐322 was safe and effective for ameliorating the DTH response and imiquimod‐induced dermatitis in mice.Conclusions and Implications: PO‐322 exerted immunosuppressive activity in vitro and in vivo by selectively inhibiting SGK1 activity. PO‐322 represents a potential lead compound for the design and development of new drugs for the treatment of autoimmune diseases.