Combination therapy with TOF might have the potential to control refractory anti-MDA5 Ab+ DM-ILD.

Objective. B and T lymphocyte attenuator (BTLA), a coreceptor expressed on lymphocytes, was recently described as an inhibitory coreceptor that negatively regulates lymphocyte activation. The purpose of this study was to investigate the role of BTLA in the regulation of immune homeostasis and the pathogenesis of autoimmunity.Methods. We examined the levels of immunoglobulins and autoantibodies to nuclear antigens and the activation status of T cells in BTLA ؊/؊ mice. We also examined histopathologic changes in the organs of BTLA ؊/؊ mice. Results. We observed that BTLA ؊/؊ mice gradually developed hypergammaglobulinemia, antinuclear antibodies, anti-SSA antibodies, anti-double-stranded DNA antibodies, and an increased number of activated CD4؉ T cells in the periphery with age. Lack of BTLA led to spontaneous development of autoimmune hepatitis-like disease characterized by an elevation in the level of transaminases, interface hepatitis, and spotty necrosis of the liver. BTLA ؊/؊ mice also showed inflammatory cell infiltration of multiple organs, including the salivary glands, lungs, and pancreas; these features are similar to those of Sjögren's syndrome, which is a frequent complication of autoimmune hepatitis. Furthermore, the survival rate of BTLA ؊/؊ mice was significantly reduced after the age of 7 months.Conclusion. Our results indicate that BTLA plays an important role in the maintenance of immune tolerance and the prevention of autoimmune diseases.

Recent studies have suggested that statins, the inhibitors for 3-hydroxy-3-methyglutaryl (HMG)-CoA reductase in the mevalonate pathway, exhibit anti-inflammatory effects. However, the immune modulatory effects of statins on the differentiation of CD4(+) T cells and their underlying mechanisms are still largely unknown. To address these issues, we examined the effect of simvastatin and inhibitors for protein farnesylation and geranylgeranylation on the differentiation of IL-17-producing T cells (T(h)17 cells) and Foxp3(+) CD4(+) T cells. Simvastatin inhibited the differentiation of T(h)17 cells through the inhibition of HMG-CoA reductase activity but enhanced the differentiation of Foxp3(+) CD4(+) T cells. Geranylgeranyltransferase I inhibitor, GGTI-298, but not farnesyltransferase inhibitor, FTI-277, mimicked the effects of simvastatin, indicating that the inhibition of protein geranylgeranylation is responsible for the effects. Moreover, Foxp3(+) CD4(+) T cells developed in the presence of transforming growth factor-beta and GGTI-298 functioned as regulatory T cells (Tregs) in in vitro T cell proliferation assay as well as in an autoimmune colitis model. Finally, GGTI-298 induced SOCS3 expression and inhibited IL-6-induced signal transducers and activators of transcription3 phosphorylation in CD4(+) T cells. Taken together, these results indicate that protein geranylgeranylation enhances the differentiation of T(h)17 cells and inhibits the differentiation of Foxp3(+) Tregs partly via the inhibition of SOCS3 expression.

Although innate immune responses are necessary for the initiation of acquired immune responses and the subsequent successful elimination of pathogens, excessive responses occasionally result in lethal endotoxic shock accompanied by a cytokine storm. B and T lymphocyte attenuator (BTLA), a coinhibitory receptor with similarities to cytotoxic T-lymphocyte antigen (CTLA)-4 and programmed death (PD)-1, is expressed in not only B and T cells but also dendritic cells (DCs) and macrophages (Mϕs). Recently, several studies have reported that BTLA-deficient (BTLA −/− ) mice show enhanced pathogen clearance compared with WT mice in early phase of infections. However, the roles of BTLA expressed on innate cells in overwhelming and uncontrolled immune responses remain unclear. Here, we found that BTLA −/− mice were highly susceptible to LPS-induced endotoxic shock. LPS-induced TNF-α and IL-12 production in DCs and Mϕs was significantly enhanced in BTLA −/− mice. BTLA −/− DCs also produced high levels of TNF-α on stimulation with Pam3CSK4 but not poly(I:C) or CpG, suggesting that BTLA functions as an inhibitory molecule on Toll-like receptor signaling at cell surface but not endosome. Moreover, BTLA −/− DCs showed enhanced MyD88- and toll/IL-1R domain-containing adaptor inducing IFN (TRIF)-dependent signaling on LPS stimulation, which is associated with impaired accumulation of Src homology 2-containing protein tyrosine phosphatase in lipid rafts. Finally, we found that an agonistic anti-BTLA antibody rescued mice from LPS-induced endotoxic shock, even if the antibody was given to mice that had developed a sign of endotoxic shock. These results suggest that BTLA directly inhibits LPS responses in DCs and Mϕs and that agonistic agents for BTLA might have therapeutic potential for LPS-induced endotoxic shock.

FDG-PET imaging has limited usefulness for the evaluation of myositis in patients with PM/DM because of its low sensitivity, although it might be useful for detection of malignancy in these patients.