Mice subcutaneously injected with bleomycin, in an experimental model of human systemic sclerosis, develop cutaneous and lung fibrosis with autoantibody production. CD19 is a general "rheostat" that defines signaling thresholds critical for humoral immune responses, autoimmunity, and cytokine production. To determine the role of CD19 in the bleomycin-induced systemic sclerosis model, we investigated the development of fibrosis and autoimmunity in CD19-deficient mice. Bleomycin-treated wild-type mice exhibited dermal and lung fibrosis, hyper-gamma-globulinemia, autoantibody production, and enhanced serum and skin expression of various cytokines, including fibrogenic interleukin-4, interleukin-6, and transforming growth factor-beta1, all of which were inhibited by CD19 deficiency. Bleomycin treatment enhanced hyaluronan production in the skin, lung, and sera. Addition of hyaluronan, an endogenous ligand for Toll-like receptor (TLR) 2 and TLR4, stimulated B cells to produce various cytokines, primarily through TLR4; CD19 deficiency suppressed this stimulation. These results suggest that bleomycin induces fibrosis by enhancing hyaluronan production, which activates B cells to produce fibrogenic cytokines mainly via TLR4 and induce autoantibody production, and that CD19 deficiency suppresses fibrosis and autoantibody production by inhibiting TLR4 signals.

Among symptom-free subjects, we found that changes in the lid margin and meibomian glands were closely related to aging. Among elderly subjects, changes in the anatomic lid margin and meibomian gland morphology were observed more frequently in men than in women. Tear function showed no association with either changes in the lid margin or function of the meibomian glands.

The high mobility group box 1 protein (HMGB-1)/adcanced glycation end products (RAGE) system is recently shown to play an important part in immune/inflammatory disorders. However, the association of this system in systemic sclerosis (SSc) remains unknown. To determine clinical association of serum levels of HMGB-1 and soluble RAGE (sRAGE) in patients with SSc, sera from 70 patients with SSc and 25 healthy controls were examined by enzyme-linked immunosorbent assay. Sera from Tight-skin mice and bleomycin-induced scleroderma mice, animal models for SSc, were also examined. Skin HMGB-1 and RAGE expression was assessed by immunohistochemistry. Serum HMGB-1 and sRAGE levels in SSc were higher than those in controls. Similarly, HMGB-1 and sRAGE levels in animal SSc models were higher than those in control mice. SSc patients with elevated HMGB-1 and sRAGE levels had more frequent involvement of several organs and immunological abnormalities compared to those with normal levels. Furthermore, HMGB-1 and sRAGE levels correlated positively with modified Rodnan total skin thickness score and negatively with pulmonary function test. HMGB-1 and sRAGE expression in the sclerotic skin was more intense than normal skin. These results suggest that elevated serum HMGB-1 and sRAGE levels are associated with the disease severity and

Mice subcutaneously injected with bleomycin, an experimental model for human systemic sclerosis, develop skin and lung fibrosis, which is mediated by inflammatory cell infiltration. This process is highly regulated by multiple adhesion molecules. To assess the role of adhesion molecules in this pathogenetic process, the bleomycin-induced fibrosis was examined in mice lacking adhesion molecules. In addition, this model does not require antigen sensitization. Therefore, we can exclude the possible role of adhesion molecules on the sensitization phase. L-selectin and/or ICAM-1 deficiency inhibited skin and lung fibrosis with decreased Th2 and Th17 cytokines and increased Th1 cytokines. By contrast, P-selectin deficiency, E-selectin deficiency with or without P-selectin blockade, or PSGL-1 deficiency augmented the fibrosis in parallel with increased Th2 and Th17 cytokines and decreased Th1 cytokines. Furthermore, loss of L-selectin and/or ICAM-1 reduced Th2 and Th17 cell numbers in bronchoalveolar lavage fluid, whereas loss of P-selectin, E-selectin, or PSGL-1 reduced Th1 cell numbers. Moreover, Th1 cells exhibited higher PSGL-1 expression and lower expression of LFA-1, a ligand for ICAM-1, while Th2 and Th17 cells showed higher LFA-1 and lower PSGL-1 expression. This study suggests that L-selectin and ICAM-1 regulate Th2 and Th17 cell accumulation into the skin and lung, leading to the development of fibrosis, and that P-selectin, E-selectin, and PSGL-1 regulate Th1 cell infiltration, resulting in the inhibition of fibrosis.

Objective. Rapamycin, a novel macrolide immunosuppressive drug, is increasingly used as an agent for posttransplant immunosuppression and treatment of autoimmune disease. The molecular mechanism related to rapamycin-mediated immunosuppression is that rapamycin binds to FK-506 binding protein 12, and the formed complex inhibits the function of the mammalian target of rapamycin (mTOR), which in turn reduces protein phosphorylation, cell cycle progression, and cytokine production. The aim of this study was to examine the effect of rapamycin against the development of fibrosis and autoimmunity in 2 different types of systemic sclerosis (SSc) model mice.Methods. Tight skin (TSK/؉) mice and bleomycininduced SSc model mice were used to evaluate the effect of rapamycin on fibrosis and immunologic abnormalities. Furthermore, the antifibrotic effect of rapamycin was assessed using TSK/؉ mouse fibroblasts.Results. Treatment with rapamycin reduced skin fibrosis of TSK/؉ mice and skin and lung fibrosis of bleomycin-induced SSc model mice. The production of fibrogenic cytokines, such as interleukin-4 (IL-4), IL-6, IL-17, and transforming growth factor ␤1, was attenuated by rapamycin. Hypergammaglobulinemia and antitopoisomerase I antibody production were also reduced by rapamycin treatment in TSK/؉ mice. In addition, mTOR expression levels were increased in TSK/؉ mouse fibroblasts compared with those in wild-type mouse fibroblasts. Rapamycin treatment inhibited proliferation and collagen production of TSK/؉ mouse fibroblasts in a dose-dependent manner.Conclusion. This study is the first to show that rapamycin has a significant inhibitory effect on fibrosis in both TSK/؉ and bleomycin-induced SSc model mice. These results suggest that rapamycin might be an attractive candidate for clinical trials in SSc patients.