Polyclonally Derived Alloantigen-Specific T Regulatory Cells Exhibit Target-Specific Suppression and Capture MHC Class II from Dendritic Cells.

Foxp3+ T regulatory (Treg) cells prevent allograft rejection and graft-versus-host disease. Although polyclonal Tregs have been used both in animal models and in humans, the fine specificity of their suppressive function is poorly defined. We have generated mouse recipient-derived alloantigen-specific Tregs in vitro and explored the fine specificity of their suppressive function and their mechanism of action in vitro and in vivo. In vitro, when alloantigen and peptide Ag were both presented on the same dendritic cell, both responses were suppressed by iTregs specific either for the alloantigen or for the peptide Ag. In vivo, iTreg suppression was limited to the cognate Ag, and no bystander suppression was observed when both allo-antigen and peptide Ag were present on the same dendritic cell. In vitro, alloantigen-specific Tregs captured cognate MHC but failed to capture noncognate MHC. Our results demonstrate that a polyclonal population of iTregs generated from naive T cells can mediate highly specific function in vivo and support the view that Treg therapy, even with unselected polyclonal populations, is likely to be target antigen-specific and that bystander responses to self-antigens or to infectious agents are unlikely.

Short-term and long-term outcomes of patients with anti-melanoma differentiation-associated gene 5 antibody-positive dermatomyositis.

OBJECTIVES: Anti-melanoma differentiation-associated gene 5 (MDA5) antibody-positive dermatomyositis (MDA5-DM) is a subtype of dermatomyositis characterized by frequent interstitial lung disease and reduced muscle involvement. This study aimed to determine the short-term and long-term outcomes of patients with MDA5-DM. METHODS: Information on baseline characteristics, treatments, and short-term and long-term outcomes of patients with MDA5-DM including survival, relapse, and the titer of anti-MDA5 antibody, was retrospectively collected. Descriptive statistics regarding clinical outcomes were calculated, and a comparison of clinical parameters between patients with and without relapse was performed. The short-term survival according to the use of Janus kinase inhibitors (JAKi) was also assessed. RESULTS: A total of 154 patients with MDA5-DM were included in the study. Forty patients (25.9%) died during the remission induction phase, with respiratory failure being the most common cause of mortality. Among the 114 patients who survived the remission induction phase, the 5-year cumulative survival and relapse-free survival rates were 96.8% and 77.4%, respectively, and 7.9% of patients achieved complete drug-free remission. Fifty-four patients achieved normalization of anti-MDA5 antibody titers and only two of them relapsed after normalization. In the severe patients, the 6-month survival rate became significantly higher after the emergence of the JAKi treatment compared with before its existence (p= 0.03). CONCLUSIONS: Although relapse often occurs, the long-term survival of MDA5-DM patients who survived the remission induction phase is generally favorable. The status of the anti-MDA5 antibody is associated with relapse. JAKi may improve the survival of refractory patients with severe MDA5-DM.