Clinical features of patients with connective tissue disease with anti-human upstream binding factor antibodies: A single-center retrospective study.

Anti-human upstream-binding factor (anti-hUBF) antibodies have been reported predominantly in patients with connective tissue diseases (CTDs); these have also been reported in patients without CTDs such as hepatocellular carcinoma. Because of the low frequency of expression and few case reports, there is no consensus on the clinical significance of these antibodies. Thus, we aimed to examine the clinical features of patients with anti-hUBF antibodies and analyzed 1042 patients with clinically suspected CTDs. The presence of anti-hUBF antibodies was screened using immunoprecipitation assays. Of the 1042 patients, 19 (1.82%) tested positive for anti-hUBF antibodies; among them, 10 (56%) were diagnosed with undifferentiated CTD (UCTD), six with systemic sclerosis (SSc) and three with other diseases. Five of the 10 patients with UCTD were referred to our hospital with suspected SSc. None of the five patients fulfilled the 2013 American College of Rheumatology/European League Against Rheumatism classification criteria, but three scored seven points, a relatively high score. Six anti-hUBF-positive patients with SSc had a significantly lower modified Rodnan skin score (mRSS) than that of anti-hUBF-negative patients with SSc (2 [0-2] vs 7 [0-49], p < 0.01). Compared with anti-topoisomerase I-positive patients, anti-hUBF-positive patients had a significantly lower mRSS (2 [0-2] vs 13 [0-42], p < 0.01) and lower incidence of scleroderma renal crisis (0 of 6 vs 8 of 184, p < 0.01). Compared with anti-centromere-positive patients, anti-hUBF-positive patients had a higher incidence of interstitial lung disease (ILD), but the difference was not statistically significant (4 of 6 vs 19 of 239). In conclusion, anti-hUBF antibodies were predominantly detected in patients with CTDs and UCTD. In patients with CTDs, SSc exhibited a high ratio, displaying a lower mRSS and higher incidence of ILD. In patients with UCTD, careful follow-up is recommended as they may develop CTDs in the future.

A role for FcγRIIB in the development of murine bleomycin-induced fibrosis.

BACKGROUND: Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by excessive fibrosis. FcγRIIB is a low-affinity receptor for the Fc fragment of IgG. FcγRIIB is expressed on the surface of various leukocyte subsets and signals negative feedback pathways to down-regulate B-cell antigen receptor signaling. OBJECTIVE: The aim of the present study was to investigate the role of FcγRIIB in the development of a murine bleomycin-induced scleroderma model. METHODS: The experimental fibrosis model was generated by the intradermal injection of bleomycin into wild-type (WT) and FcγRIIB-deficient (FcγRIIB-/-) mice. We histologically assessed skin and lung fibrosis as well as inflammatory cell infiltration. Cytokine and chemokine expression levels were measured with RT-PCR. RESULTS: The severity of fibrosis in the skin and lung was significantly worse in FcγRIIB-/- mice than in WT mice. In the skin of bleomycin-treated mice, the numbers of CD8+ T cells, F4/80+ macrophages, MPO+ neutrophils, NK1.1+NK cells, and B220+ B cells were significantly higher in FcγRIIB-/- mice than in WT mice. The expression of TNF-α and IL-1ß was significantly higher in FcγRIIB-/- mice than in WT mice as was the expression of ICAM-1, CXCL2, and CCL3 in the affected skin. An adoptive transfer of splenic leukocytes from FcγRIIB-/- mice into WT mice showed exacerbated skin and lung fibrosis compared to WT mice without an adoptive transfer. CONCLUSION: These results indicate that FcγRIIB plays an inhibitory role in skin and lung fibrosis. Moreover, modulating FcγRIIB signaling has potential as a therapeutic approach for SSc.

Suppression of IL-23-mediated psoriasis-like inflammation by regulatory B cells.

Psoriasis is an inflammatory cutaneous disease mediated by T-cell dependent immune responses; however, B cells are also considered to play an important role its development. Regulatory B cells (Bregs) regulate immune responses negatively through interleukin-10 (IL-10) production. This study aimed to investigate the role of Bregs in IL-23-mediated psoriasis-like inflammation in mice. Psoriasis-like inflammation was induced in B cell-specific phosphatase and tensin homolog (PTEN)-deficient mice, in which Bregs were significantly expanded, and in their controls, by intradermal injection of 20 µL phosphate-buffered saline (PBS) containing 0.5 µg rmIL-23 into one ear, every other day for 16 days. IL-23-mediated psoriasis-like inflammation was suppressed in B cell-specific PTEN-deficient mice along with decreased ear thickness and epidermal thickness on day 15. Moreover, adoptive transfer of B1 B cells suppressed IL-23-mediated psoriasis-like inflammation. rmIL-23-injected B cell-specific PTEN-deficient mice showed expanded regulatory T cells (Tregs) in the spleen and draining lymph nodes along with increased Bregs. Further, T helper (Th) 17 differentiation in the rmIL-23-injected ear was suppressed in B cell-specific PTEN-deficient mice. Overall, these results indicate that increased Bregs suppress IL-23-mediated psoriasis-like inflammation through Treg expansion and inhibition of Th17 differentiation. Thus, targeting Bregs may be a feasible treatment strategy for psoriasis.

Immunomodulating role of the JAKs inhibitor tofacitinib in a mouse model of bleomycin-induced scleroderma.

BACKGROUND: Janus kinase (JAK)-signal transducer and activator of transcription (STAT) was hyperactivated in biopsies from patients with systemic sclerosis (SSc) and in several autoimmune disease models. Tofacitinib, a pan-JAK inhibitor, blocks the downstream signaling of multiple cytokines and has exhibited therapeutic efficacy in various autoimmune diseases, although its immunomodulating property in scleroderma is unclear. OBJECTIVE: To evaluate the effect of tofacitinib on the modulation of cytokine-producing T and B cells, and proinflammatory cells in a mouse model of SSc. METHODS: Bleomycin (BLM)-induced SSc was generated by intradermal injection of BLM or PBS for control. Mice received intraperitoneal tofacitinib (20 mg/kg) or vehicle 3 times per week from day 0-28. Mice were sacrificed at day 28 after the last BLM/PBS injection. RESULTS: Tofacitinib administration significantly alleviated fibrosis of the skin and lungs in scleroderma mouse model. Furthermore, tofacitinib suppressed adaptive and innate immune responses by reducing splenocytes, total lymphocytes, CD4+ T helper cells (especially Th2 and Th17 subtypes), IL-6-producing effector B cells, PDCA-1+ dendritic cells in the spleen, and infiltration of F4/80+, CD206+ and CD163+ macrophages in the skin and lungs. Conversely, tofacitinib increased the proportions of splenic regulatory T and B cells. The mRNA expression of extracellular matrix proteins and fibrogenic cytokines was downregulated by tofacitinib in both the skin and lungs. CONCLUSION: These observations suggest JAK inhibition as a therapeutic approach for the treatment of inflammatory and fibrotic diseases, and highlight the potential of tofacitinib as a promising candidate for treating patients with scleroderma.

BAFF inhibition attenuates fibrosis in scleroderma by modulating the regulatory and effector B cell balance.

Systemic sclerosis (SSc) is an autoimmune disease characterized by skin and lung fibrosis. More than 90% of patients with SSc are positive for autoantibodies. In addition, serum B cell activating factor (BAFF) level is correlated with SSc severity and activity. Thus, B cells are considered to play a pathogenic role in SSc. However, there are two opposing subsets: regulatory B cells (Bregs) and effector B cells (Beffs). Interleukin-10 (IL-10)-producing Bregs negatively regulate the immune response, while IL-6-producing Beffs positively regulate it. Therefore, a protocol that selectively depletes Beffs would represent a potent therapy for SSc. The aims of this study were to investigate the roles of Bregs and Beffs in SSc and to provide a scientific basis for developing a new treatment strategy targeting B cells. A bleomycin-induced scleroderma model was induced in mice with a B cell-specific deficiency in IL-6 or IL-10. We also examined whether BAFF regulates cytokine-producing B cells and its effects on the scleroderma model. IL-6-producing Beffs increased in number and infiltrated the inflamed skin in the scleroderma model. The skin and lung fibrosis was attenuated in B cell-specific IL-6-deficient mice, whereas B cell-specific IL-10-deficient mice showed more severe fibrosis. In addition, BAFF increased Beffs but suppressed Bregs. Furthermore, BAFF antagonist attenuated skin and lung fibrosis in the scleroderma model with reduction of Beffs but not of Bregs. The current study indicates that Beffs play a pathogenic role in the scleroderma model, while Bregs play a protective role. BAFF inhibition is a potential therapeutic strategy for SSc via alteration of B cell balance.

Blockade of p38 Mitogen-Activated Protein Kinase Inhibits Murine Sclerodermatous Chronic Graft-versus-Host Disease.

Bone marrow transplantation (BMT) of B10.D2 mice into sublethally irradiated BALB/c mice across minor histocompatibility loci is a well-established animal model for human sclerodermatous chronic graft-versus-host disease (Scl-cGVHD) and systemic sclerosis (SSc). The p38 mitogen-activated protein kinase (MAPK) pathway is a key regulator of inflammation and cytokine production. Furthermore, the activation of p38 MAPK plays an important role in collagen production in SSc. We investigated the effects of p38 MAPK inhibitor, VX-702, on Scl-cGVHD mice. VX-702 was orally administered to Scl-cGVHD mice from day 7 to 35 after BMT. We compared skin fibrosis of Scl-cGVHD mice between the VX-702-treated group and control group. Allogeneic BMT increased the phosphorylation of p38 MAPK in the skin. The administration of VX-702 attenuated the skin fibrosis of Scl-cGVHD compared to the control mice. Immunohistochemical staining showed that VX-702 suppressed the infiltration of CD4+ T cells, CD8+ T cells, and CD11b+ cells into the dermis of Scl-cGVHD mice compared to the control mice. VX-702 attenuated the mRNA expression of extracellular matrix and fibrogenic cytokines, such as IL-6 and IL-13, in the skin of Scl-cGVHD mice. In addition, VX-702 directly inhibited collagen production from fibroblasts in vitro. VX-702 was shown to be a promising candidate for use in treating patients with Scl-cGVHD and SSc.