Solid organ transplantation has significantly improved the survival rate of patients with terminal organ failure. However, its success is often compromised by allograft rejection, a process in which T helper 17 (Th17) cells play a crucial role. These cells facilitate rejection by enhancing neutrophil infiltration into the graft and by activating endothelial cells and fibroblasts. Additionally, Th17 cells can trigger the activation of other T cell types, including Th1, Th2, and CD8+ T cells, further contributing to rejection. An imbalance between Th17 and regulatory T cells (Tregs) is known to promote rejection. To counteract this, immunosuppressive drugs have been developed to inhibit T cell activity and foster transplant tolerance. Another approach involves the adoptive transfer of regulatory cells, such as Tregs and myeloid-derived suppressor cells, to dampen T cell functions. This review primarily focuses on the roles of Th17 cells in rejection and their interactions with other T cell subsets. We also explore various strategies aimed at suppressing T cells to induce tolerance.

Systemic sclerosis (SS) is an autoimmune disease and pathological mechanisms of SS are unclear. In this study, we investigated the role of T cells in the progression of SS using SKG mice and humanized mice. SKG mice have a spontaneous point mutation in ZAP70. We induced scleroderma in SKG mice and a humanized SS mouse model to assess whether T cell-mediated immune responses induce SS. As a result, we found increased dermal thickness, fibrosis, and lymphocyte infiltration in skin tissue in SKG SS mice compared to BALB/c mice (control). Also, blood cytokine level, including IL-4- and IFN-α which are produced by CD4+ T cells via STIM1/STING/STAT6/IRF3 signaling pathways, were increased in SKG mice. Interestingly, skin fibrosis was reduced by inhibiting STING pathway in skin fibroblast.Next, we demonstrated the pathophysiological role of IL-4 and IFN-α in skin fibrosis using a humanized SS mouse model and found increased IL-4- and IFN-α-producing CD4+ T cells and fibrosis. In this study, we found that STING-induced production of IL-4- and type I IFN by CD4+ T cells is a key factor in mouse model and humanized mouse model of SS. Our findings suggest that the STING/STAT6/IRF3 signaling pathways are potential therapeutic targets in SS.

Solid organ transplantation has significantly improved the survival rate of patients with terminal organ failure. However, its success is often compromised by allograft rejection, a process in which T helper 17 (Th17) cells play a crucial role. These cells facilitate rejection by enhancing neutrophil infiltration into the graft and by activating endothelial cells and fibroblasts. Additionally, Th17 cells can trigger the activation of other T cell types, including Th1, Th2, and CD8+ T cells, further contributing to rejection. An imbalance between Th17 and regulatory T cells (Tregs) is known to promote rejection. To counteract this, immunosuppressive drugs have been developed to inhibit T cell activity and foster transplant tolerance. Another approach involves the adoptive transfer of regulatory cells, such as Tregs and myeloid-derived suppressor cells, to dampen T cell functions. This review primarily focuses on the roles of Th17 cells in rejection and their interactions with other T cell subsets. We also explore various strategies aimed at suppressing T cells to induce tolerance.

Solid organ transplantation has significantly improved the survival rate of patients with terminal organ failure. However, its success is often compromised by allograft rejection, a process in which T helper 17 (Th17) cells play a crucial role. These cells facilitate rejection by enhancing neutrophil infiltration into the graft and by activating endothelial cells and fibroblasts. Additionally, Th17 cells can trigger the activation of other T cell types, including Th1, Th2, and CD8+ T cells, further contributing to rejection. An imbalance between Th17 and regulatory T cells (Tregs) is known to promote rejection. To counteract this, immunosuppressive drugs have been developed to inhibit T cell activity and foster transplant tolerance. Another approach involves the adoptive transfer of regulatory cells, such as Tregs and myeloid-derived suppressor cells, to dampen T cell functions. This review primarily focuses on the roles of Th17 cells in rejection and their interactions with other T cell subsets. We also explore various strategies aimed at suppressing T cells to induce tolerance.

Systemic sclerosis (SS) is an autoimmune disease and pathological mechanisms of SS are unclear. In this study, we investigated the role of T cells in the progression of SS using SKG mice and humanized mice. SKG mice have a spontaneous point mutation in ZAP70. We induced scleroderma in SKG mice and a humanized SS mouse model to assess whether T cell-mediated immune responses induce SS. As a result, we found increased dermal thickness, fibrosis, and lymphocyte infiltration in skin tissue in SKG SS mice compared to BALB/c mice (control). Also, blood cytokine level, including IL-4- and IFN-α which are produced by CD4+ T cells via STIM1/STING/STAT6/IRF3 signaling pathways, were increased in SKG mice. Interestingly, skin fibrosis was reduced by inhibiting STING pathway in skin fibroblast.Next, we demonstrated the pathophysiological role of IL-4 and IFN-α in skin fibrosis using a humanized SS mouse model and found increased IL-4- and IFN-α-producing CD4+ T cells and fibrosis. In this study, we found that STING-induced production of IL-4- and type I IFN by CD4+ T cells is a key factor in mouse model and humanized mouse model of SS. Our findings suggest that the STING/STAT6/IRF3 signaling pathways are potential therapeutic targets in SS.

Solid organ transplantation has significantly improved the survival rate of patients with terminal organ failure. However, its success is often compromised by allograft rejection, a process in which T helper 17 (Th17) cells play a crucial role. These cells facilitate rejection by enhancing neutrophil infiltration into the graft and by activating endothelial cells and fibroblasts. Additionally, Th17 cells can trigger the activation of other T cell types, including Th1, Th2, and CD8+ T cells, further contributing to rejection. An imbalance between Th17 and regulatory T cells (Tregs) is known to promote rejection. To counteract this, immunosuppressive drugs have been developed to inhibit T cell activity and foster transplant tolerance. Another approach involves the adoptive transfer of regulatory cells, such as Tregs and myeloid-derived suppressor cells, to dampen T cell functions. This review primarily focuses on the roles of Th17 cells in rejection and their interactions with other T cell subsets. We also explore various strategies aimed at suppressing T cells to induce tolerance.

Systemic sclerosis (SS) is an autoimmune disease and pathological mechanisms of SS are unclear. In this study, we investigated the role of T cells in the progression of SS using SKG mice and humanized mice. SKG mice have a spontaneous point mutation in ZAP70. We induced scleroderma in SKG mice and a humanized SS mouse model to assess whether T cell-mediated immune responses induce SS. As a result, we found increased dermal thickness, fibrosis, and lymphocyte infiltration in skin tissue in SKG SS mice compared to BALB/c mice (control). Also, blood cytokine level, including IL-4- and IFN-α which are produced by CD4+ T cells via STIM1/STING/STAT6/IRF3 signaling pathways, were increased in SKG mice. Interestingly, skin fibrosis was reduced by inhibiting STING pathway in skin fibroblast.Next, we demonstrated the pathophysiological role of IL-4 and IFN-α in skin fibrosis using a humanized SS mouse model and found increased IL-4- and IFN-α-producing CD4+ T cells and fibrosis. In this study, we found that STING-induced production of IL-4- and type I IFN by CD4+ T cells is a key factor in mouse model and humanized mouse model of SS. Our findings suggest that the STING/STAT6/IRF3 signaling pathways are potential therapeutic targets in SS.

Osteoarthritis (OA) involves cartilage degeneration, thereby causing inflammation and pain. Cardiovascular diseases, such as dyslipidemia, are risk factors for OA; however, the mechanism is unclear. We investigated the effect of dyslipidemia on the development of OA. Treatment of cartilage cells with low-density lipoprotein (LDL) enhanced abnormal autophagy but suppressed normal autophagy and reduced the activity of transcription factor EB (TFEB), which is important for the function of lysosomes. Treatment of LDL-exposed chondrocytes with rapamycin, which activates TFEB, restored normal autophagy. Also, LDL enhanced the inflammatory death of chondrocytes, an effect reversed by rapamycin. In an animal model of hyperlipidemia-associated OA, dyslipidemia accelerated the development of OA, an effect reversed by treatment with a statin, an anti-dyslipidemia drug, or rapamycin, which activates TFEB. Dyslipidemia reduced the autophagic flux and induced necroptosis in the cartilage tissue of patients with OA. The levels of triglycerides, LDL, and total cholesterol were increased in patients with OA compared to those without OA. The C-reactive protein level of patients with dyslipidemia was higher than that of those without dyslipidemia after total knee replacement arthroplasty. In conclusion, oxidized LDL, an important risk factor of dyslipidemia, inhibited the activity of TFEB and reduced the autophagic flux, thereby inducing necroptosis in chondrocytes.

Background: Orthotopic liver transplantation is the only option for patients with end-stage liver disease and hepatocellular carcinoma. Post-transplant immunosuppressive therapy is important to prevent graft failure. We investigated the effectiveness of tacrolimus (FK506) and their mechanisms for liver transplant immune tolerance in an outbred rat LT model. Results: To investigate the therapeutic effect of the FK506 on outbred rat LT model, FK506 and postoperative therapy were administered subcutaneously once or twice daily to transplanted rats. Histopathological and immunohistochemical analyses were conducted for all groups. The regulation of inflammatory cytokine signaling in the spleen was analyzed by flow cytometry. FK506 attenuated allograft rejection and increased survival in rat orthotopic liver transplantation models. The FK506-treated group had reduced serum levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase. Furthermore, FK506 decreased the expression of inflammatory cytokines and the activation of pathogenic Th1 and Th17 cells in the liver. Conclusions Taken together, we revealed that FK506 ameliorated strong allograft rejection in outbred liver transplantation model by anti-inflammatory effect and inhibitory peroperty of pathogenic T cells.

Osteoarthritis (OA) is a common degenerative joint disease characterized by breakdown of joint cartilage. Mitochondrial dysfunction of the chondrocyte is a risk factor for OA progression. We examined the therapeutic potential of mitochondrial transplantation for OA. Mitochondria were injected into the knee joint of monosodium iodoacetateinduced OA rats. Chondrocytes from OA rats or patients with OA were cultured to examine mitochondrial function in cellular pathophysiology. Pain, cartilage destruction, and bone loss were improved in mitochondrial transplanted-OA rats. The transcript levels of IL-1β, TNF-α, matrix metallopeptidase 13, and MCP-1 in cartilage were markedly decreased by mitochondrial transplantation. Mitochondrial function, as indicated by membrane potential and oxygen consumption rate, in chondrocytes from OA rats was improved by mitochondrial transplantation. Likewise, the mitochondrial function of chondrocytes from OA patients was improved by coculture with mitochondria. Furthermore, inflammatory cell death was significantly decreased by coculture with mitochondria. Mitochondrial transplantation ameliorated OA progression, which is caused by mitochondrial dysfunction. These results suggest the therapeutic potential of mitochondrial transplantation for OA.