Unraveling the role of MiR-181 in skin fibrosis pathogenesis by targeting NUDT21.

Systemic sclerosis (SSc) is a life-threatening autoimmune disease characterized by widespread fibrosis in the skin and several internal organs. Nudix Hydrolase 21 (NUDT2 or CFIm25) downregulation in fibroblasts is known to play detrimental roles in both skin and lung fibrosis. This study aims to investigate the upstream mechanisms that lead to NUDT21 repression in skin fibrosis. We identified transforming growth factor ß (TGFß1) as the primary cytokine that downregulated NUDT21 in normal skin fibroblasts. In the bleomycin-induced dermal fibrosis model, consistent with the peak activation of TGFß1 at the late fibrotic stage, NUDT21 was downregulated at this stage, and delayed NUDT21 knockdown during this fibrotic phase led to enhanced fibrotic response to bleomycin. Further investigation suggested TGFß downregulated NUDT21 through microRNA (miRNA) 181a and 181b induction. Both miR-181a and miR-181b were elevated in bleomycin-induced skin fibrosis in mice and primary fibroblasts isolated from SSc patients, and they directly targeted NUDT21 and led to its downregulation in skin fibroblasts. Functional studies demonstrated that miR-181a and miR-181b inhibitors attenuated bleomycin-induced skin fibrosis in mice in association with decreased NUDT21 expression, while miR-181a and miR-181b mimics promoted bleomycin-induced fibrosis. Overall, these findings suggest a novel role for miR-181a/b in SSc pathogenesis by repressing NUDT21 expression.

Silica's silent threat: Contributing to skin fibrosis in systemic sclerosis by targeting the HDAC4/Smad2/3 pathway.

Nowadays, silica products are widely used in daily life, especially in skin applications, which inevitably increases the risk of silica exposure in general population. However, inadequate awareness of silica's potential hazards and lack of self-protection are of concern. Systemic sclerosis (SSc) is characterized by progressive tissue fibrosis under environmental and genetic interactions. Silica exposure is considered an important causative factor for SSc, but its pathogenesis remains unclear. Within this study, we showed that lower doses of silica significantly promoted the proliferation, migration, and activation of human skin fibroblasts (HSFs) within 24 h. Silica injected subcutaneously into mice induced and exacerbated skin fibrosis. Notably, silica increased histone deacetylase-4 (HDAC4) expression by inducing its DNA hypomethylation in normal HSFs. The elevated HDAC4 expression was also confirmed in SSc HSFs. Furthermore, HDAC4 was positively correlated with Smad2/3 phosphorylation and COL1, α-SMA, and CTGF expression. The HDAC4 inhibitor LMK235 mitigated silica-induced upregulation of these factors and alleviated skin fibrosis in SSc mice. Taken together, silica induces and exacerbates skin fibrosis in SSc patients by targeting the HDAC4/Smad2/3 pathway. Our findings provide new insights for evaluating the health hazards of silica exposure and identify HDAC4 as a potential interventional target for silica-induced SSc skin fibrosis.

MicroRNA-21a-5p inhibition alleviates systemic sclerosis by targeting STAT3 signaling.

BACKGROUND: MicroRNA (miRNA)-21-5p participates in various biological processes, including cancer and autoimmune diseases. However, its role in the development of fibrosis in the in vivo model of systemic sclerosis (SSc) has not been reported. This study investigated the effects of miRNA-21a-5p overexpression and inhibition on SSc fibrosis using a bleomycin-induced SSc mouse model. METHODS: A murine SSc model was induced by subcutaneously injecting 100 µg bleomycin dissolved in 0.9% NaCl into C57BL/6 mice daily for 5 weeks. On days 14, 21, and 28 from the start of bleomycin injection, 100 µg pre-miRNA-21a-5p or anti-miRNA-21a-5p in 1 mL saline was hydrodynamically injected into the mice. Fibrosis analysis was conducted in lung and skin tissues of SSc mice using hematoxylin and eosin as well as Masson's trichrome staining. Immunohistochemistry was used to examine the expression of inflammatory cytokines, phosphorylated signal transducer and activator of transcription-3 (STAT3) at Y705 or S727, and phosphatase and tensin homologue deleted on chromosome-10 (PTEN) in skin tissues of SSc mice. RESULTS: MiRNA-21a-5p overexpression promoted lung fibrosis in bleomycin-induced SSc mice, inducing infiltration of cells expressing TNF-α, IL-1ß, IL-6, or IL-17, along with STAT3 phosphorylated cells in the lesional skin. Conversely, anti-miRNA-21a-5p injection improved fibrosis in the lung and skin tissues of SSc mice, reducing the infiltration of cells secreting inflammatory cytokines in the skin tissue. In particular, it decreased STAT3-phosphorylated cell infiltration at Y705 and increased the infiltration of PTEN-expressing cells in the skin tissue of SSc mice. CONCLUSION: MiRNA-21a-5p promotes fibrosis in an in vivo murine SSc model, suggesting that its inhibition may be a therapeutic strategy for improving fibrosis in SSc.

Therapeutic management of fibrosis in systemic sclerosis patients - an analysis from the Swiss EUSTAR cohort.

OBJECTIVES: Systemic sclerosis is a chronic autoimmune connective tissue disease leading to microvascular and fibrotic manifestations in multiple organs. Several treatment options and recommendations from different European countries are available. In this study, for which the ambit is Switzerland specifically, we aim to describe the treatment patterns of systemic sclerosis patients with fibrotic manifestations. METHODS: Systemic sclerosis patients were selected from six Swiss tertiary centres recorded in the multicentre, prospective European Scleroderma Trials and Research (EUSTAR) registry. Patients fulfilling the 2013 ACR/EULAR systemic sclerosis classification criteria at baseline were included. To determine the differences in treatment of varying degrees of fibrosis, four groups were identified: (1) patients with a modified Rodnan skin score (mRSS) >0; (2) those with mRSS ≥7; (3) those with interstitial lung disease (SSc-ILD), diagnosed by either chest X-Ray or high-resolution computed tomography; and (4) patients fulfilling one of the additional criteria for extensive interstitial lung disease, defined as interstitial lung disease involvement of >20% in high-resolution computed tomography, dyspnea NYHA-stage 3/4, or a predicted forced vital capacity (FVC) of <70%. RESULTS: A total of 590 patients with systemic sclerosis fulfilled the inclusion criteria. In this cohort, 421 (71.4%) had mRSS >0, of whom 195 (33.1%) had mRSS ≥7; interstitial lung disease was diagnosed in 198 of 456 (43.4%), of whom 106 (18.0 %) showed extensive interstitial lung disease. Regarding non-biologic disease-modifying medications (DMARDs), the most frequently prescribed was methotrexate, followed by hydroxychloroquine and mycophenolate mofetil. Rituximab and tocilizumab were most frequently used among the biologic DMARDs. Specifically, 148/372 (39.8%) of treated patients with skin fibrosis received methotrexate, mycophenolate mofetil or rituximab, and 80/177 (45.2%) with interstitial lung disease received cyclophosphamide, mycophenolate mofetil, tocilizumab or rituximab. Most patients received a proton-pump inhibitor, and few patients underwent hematopoietic stem cell transplantation. CONCLUSION: Overall, in Switzerland, a wide range of medications is prescribed for systemic sclerosis patients. This includes modern, targeted treatments for which randomised controlled clinical trial have been recently reported.

Systemic Scleroderma Induced by Nivolumab in Malignant Melanoma.

BACKGROUND: Immunotherapy using immune checkpoint inhibitors is not devoid of immune-related adverse events (irAEs) including rheumatological conditions. CASE REPORT: We report a rare case of a 47-year-old woman with metastatic melanoma who developed systemic scleroderma after initiating nivolumab. The patient displayed inflammatory arthralgias, morning stiffness, and classical cutaneous manifestations of the disease. Clinical evaluations also revealed carpal tunnel syndrome, cardiac involvement, and dyspnea. RNA-Polymerase III antibodies were positive. Nivolumab, an anti-PD-1 antibody, was considered as a potential trigger for this condition. CONCLUSION: To our knowledge, this is the first case of nivolumab-induced systemic scleroderma in the context of melanoma described in the literature that fulfills the classification criteria of the disease. This case underscores the need for increased awareness of immune-related adverse events in patients receiving immune checkpoint inhibitors, emphasizing timely intervention and further research.

De novo Connective Tissue Disorders as Immune-related Adverse Events.

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment through blocking immunoregulatory pathways, resulting in augmented antitumor responses. However, ICIs can cause inflammatory autoimmune toxicities, known as immune-related adverse events (irAEs). Common rheumatic irAEs include inflammatory arthritis, polymyalgia rheumatica-like symptoms, and myositis. Fewer cases of de novo connective tissue disease as irAEs have been described and have mainly presented with cutaneous manifestations of systemic lupus erythematosus (SLE) and systemic sclerosis (SSc). Treatments include glucocorticoids and steroid-sparing agents such as hydroxychloroquine, mycophenolate mofetil, and methotrexate with improvement of symptoms. In this review, the authors discuss immune-related SLE and SSc and their management.

Skin and lung fibrosis induced by bleomycin in mice: a systematic review.

OBJECTIVE: Scleroderma, or systemic sclerosis (SSc), is a chronic autoimmune connective disease with an unknown etiology and poorly understood pathogenesis. The striking array of autoimmune, vascular, and fibrotic changes that develop in almost all patients makes SSc unique among connective tissue diseases. Although no animal model developed for SSc to date fully represents all features of human disease, some animal models that demonstrate features of SSc may help to better understand the pathogenesis of the disease and to develop new therapeutic options. In this review, we aimed to evaluate skin fibrosis and lung involvement in a bleomycin (BLM)-induced mouse model and to evaluate the differences between studies. METHODS: A systematic literature review (PRISMA guideline) on PubMed and EMBASE (until May 2023, without limits) was performed. A primary literature search was conducted using the PubMed and EMBASE databases for all articles published from 1990 to May 2023. Review articles, human studies, and non-dermatological studies were excluded. Of the 38 non-duplicated studies, 20 articles were included. RESULTS: Among inducible animal models, the BLM-induced SSc is still the most widely used. In recent years, the measurement of tissue thickness between the epidermal-dermal junction and the dermal-adipose tissue junction (dermal layer) has become more widely accepted. CONCLUSIONS: In animal studies, it is important to simultaneously evaluate lung tissues in addition to skin fibrosis induced in mice by subcutaneous BLM application, following the 3R (replacement, reduction, and refinement) principle to avoid cruelty to animals.

Tree shrews as a new animal model for systemic sclerosis research.

Objective: Systemic sclerosis (SSc) is a chronic systemic disease characterized by immune dysregulation and fibrosis for which there is no effective treatment. Animal models are crucial for advancing SSc research. Tree shrews are genetically, anatomically, and immunologically closer to humans than rodents. Thus, the tree shrew model provides a unique opportunity for translational research in SSc. Methods: In this study, a SSc tree shrew model was constructed by subcutaneous injection of different doses of bleomycin (BLM) for 21 days. We assessed the degree of inflammation and fibrosis in the skin and internal organs, and antibodies in serum. Furthermore, RNA sequencing and a series of bioinformatics analyses were performed to analyze the transcriptome changes, hub genes and immune infiltration in the skin tissues of BLM induced SSc tree shrew models. Multiple sequence alignment was utilized to analyze the conservation of selected target genes across multiple species. Results: Subcutaneous injection of BLM successfully induced a SSc model in tree shrew. This model exhibited inflammation and fibrosis in skin and lung, and some developed esophageal fibrosis and secrum autoantibodies including antinuclear antibodies and anti-scleroderma-70 antibody. Using RNA sequencing, we compiled skin transcriptome profiles in SSc tree shrew models. 90 differentially expressed genes (DEGs) were identified, which were mainly enriched in the PPAR signaling pathway, tyrosine metabolic pathway, p53 signaling pathway, ECM receptor interaction and glutathione metabolism, all of which are closely associated with SSc. Immune infiltration analysis identified 20 different types of immune cells infiltrating the skin of the BLM-induced SSc tree shrew models and correlations between those immune cells. By constructing a protein-protein interaction (PPI) network, we identified 10 hub genes that were significantly highly expressed in the skin of the SSc models compared to controls. Furthermore, these genes were confirmed to be highly conserved in tree shrews, humans and mice. Conclusion: This study for the first time comfirmed that tree shrew model of SSc can be used as a novel and promising experimental animal model to study the pathogenesis and translational research in SSc.

Dangui Huoxue Preparation (DHP) Ameliorates Skin Fibrosis, Inflammation, and Vasculopathy in the Bleomycin-Induced Murine Model of Systemic Sclerosis.

Systemic sclerosis (SSc) is an immune-mediated rheumatic disease that is characterized by fibrosis of the skin and internal organs and vasculopathy with poor prognosis. Dangui Huoxue Preparation (DHP) is a clinically effective traditional Chinese herbal formula for the treatment of SSc in the hospital. This study aims to investigate the therapeutic effects and underlying molecular mechanisms of DHP in the treatment of SSc. SSc mice models are induced by bleomycin (BLM). Tissues of DHP group, normal control group, and positive control drug Sanqi Tongshu Capsule (STC) group are collected for inflammation, fibrosis, and vasculopathy. Also, the human dermal fibroblasts (HDF) stimulated with TGF-ß1 are analyzed for in vitro study. The expression levels of MCP-1, IFN-γ, IL-1ß, IL-10, Fizz1, iNOS, and IL12p40, and the mRNA levels of Col1a1, Col1a2, Col3a1, and Col5a1 are significantly decreased in all DHP groups and STC group compare with those in the BLM group. The main drug of DHP inhibits the proliferation and migration of HDF, reduces Ctgf, Itgb3, Itgb5 expression, and also inhibits the Smad3 pathway. In conclusion, DHP can ameliorate SSc skin inflammation, fibrosis, and vasculopathy, possibly suppressing the TGF-ß1/Smad3 signaling pathway through extracellular and intracellular mechanisms.

Efficacy and safety of tocilizumab in Japanese patients with systemic sclerosis and associated interstitial lung disease: A subgroup analysis of a global, randomised, controlled Phase 3 trial.

OBJECTIVES: The aim of this article is to investigate the efficacy and safety of tocilizumab in Japanese patients with systemic sclerosis. METHODS: Post hoc subgroup analysis of a global, randomised, controlled trial in patients treated with weekly tocilizumab 162 mg or placebo subcutaneously in a 48-week double-blind period (tocilizumab and placebo groups) followed by tocilizumab for 48 weeks in an open-label extension (continuous-tocilizumab and placebo-tocilizumab groups). RESULTS: Among 20 patients, 12 were randomised to tocilizumab (all had interstitial lung disease) and eight were randomised to placebo (six had interstitial lung disease). The modified Rodnan skin score improved in both treatment groups. The mean change in percent-predicted forced vital capacity was 3.3% [95% confidence interval (CI), -2.5 to 9.0] for tocilizumab and -3.8% (95% CI, -9.9 to 2.2) for placebo in the double-blind period and 2.0% (95% CI, -0.7 to 4.6) for continuous-tocilizumab and -1.4% (95% CI, -6.7 to 4.0) for placebo-tocilizumab in the open-label extension. Rates of serious adverse events per 100 patient-years were 19.3 for tocilizumab and 26.8 for placebo in the double-blind period and 0.0 for continuous-tocilizumab and 13.6 for placebo-tocilizumab in the open-label period. CONCLUSIONS: The efficacy and safety of tocilizumab in patients with systemic sclerosis were consistent between the Japanese subpopulation and the global trial population.

PPARγ partial agonist LPSF/GQ-16 prevents dermal and pulmonary fibrosis in HOCl-induced systemic sclerosis (SSc) and modulates cytokine production in PBMC of SSc patients.

Thiazolidinediones (TZD) are synthetic molecules that have a range of biological effects, including antifibrotic and anti-inflammatory, and they may represent a promising therapeutic strategy for systemic sclerosis (SSc). The aim of this study was to investigate the immunomodulatory and antifibrotic properties of LPSF/GQ-16, a TZD derivative, in peripheral blood mononuclear cells (PBMC) from SSc patients and in a murine model of SSc HOCl-induced. The PBMC of 20 SSc patients were stimulated with phytohemagglutinin (PHA) and treated with LPSF/GQ-16 for 48 h, later cytokines in the culture supernatants were quantified by sandwich enzyme-linked immunosorbent assay (ELISA) or cytometric bead array (CBA). Experimental SSc was induced by intradermal injections of hypochlorous acid (HOCl) for 6 weeks. HOCl-induced SSc mice received daily treatment with LPSF/GQ-16 (30 mg/kg) through intraperitoneal injections during the same period. Immunological parameters were evaluated by flow cytometry and ELISA, and dermal and pulmonary fibrosis were evaluated by RT-qPCR, hydroxyproline dosage and histopathological analysis. In PBMC cultures, it was possible to observe that LPSF/GQ-16 modulated the secretion of cytokines IL-2 (p < 0.001), IL-4 (p < 0.001), IL-6 (p < 0.001), IL-17A (p = 0.006), TNF (p < 0.001) and IFN-γ (p < 0.001). In addition, treatment with LPSF/GQ-16 in HOCl-induced SSc mice promoted a significant reduction in dermal thickening (p < 0.001), in the accumulation of collagen in the skin (p < 0.001), down-regulated the expression of fibrosis markers in the skin (Col1a1, α-Sma and Tgfß1, p < 0.001 for all) and lungs (Il4 and Il13, p < 0.001 for both), as well as reduced activation of CD4 + T cells (p < 0.001), B cells (p < 0.001) and M2 macrophages (p < 0.001). In conclusion, LPSF/GQ-16 showed immunomodulatory and antifibrotic properties, demonstrating the therapeutic potential of this molecule for SSc.

Antifibrotic effect of apremilast in systemic sclerosis dermal fibroblasts and bleomycin-induced mouse model.

Phosphodiesterase (PDE) 4 inhibitors have been reported to suppress the progression of dermal fibrosis in patients with systemic sclerosis (SSc); however, the precise mechanisms remain to be elucidated. Therefore, we conducted experiments focusing on the antifibrotic and anti-inflammatory effects of apremilast using dermal fibroblasts derived from patients with SSc and an SSc mouse model. Dermal fibroblasts derived from healthy controls and patients with SSc were incubated with apremilast in the presence or absence of 10 ng/ml transforming growth factor (TGF)-ß1 for the measurement of intracellular cAMP levels and evaluation of mRNA and protein expression. A bleomycin-induced dermal fibrosis mouse model was used to evaluate the inhibitory effects of apremilast on the progression of dermal fibrosis. Intracellular cAMP levels were significantly reduced in dermal fibroblasts derived from patients with SSc compared with those derived from healthy controls. Apremilast reduced the mRNA expression of profibrotic markers and the protein expression of type I collagen and Cellular Communication Network Factor 2 (CCN2) in dermal fibroblasts. Additionally, apremilast inhibited the progression of dermal fibrosis in mice, partly by acting on T cells. These results suggest that apremilast may be a potential candidate for treating dermal fibrosis in SSc.

Phenotyping by persistent inflammation in systemic sclerosis associated interstitial lung disease: a EUSTAR database analysis.

BACKGROUND: Systemic sclerosis (SSc) is a heterogeneous disease with frequently associated interstitial lung disease (SSc-ILD). We aimed to determine the prognostic potential of phenotyping patients with SSc and SSc-ILD by inflammation and to describe disease trajectories stratified by inflammation and immunosuppressive treatment. METHODS: Patients from the European Scleroderma Trials and Research (EUSTAR) group cohort were allocated to persistent inflammatory, intermediate and non-inflammatory phenotypes if C-reactive protein (CRP) levels were ≥5 mg/L at ≥80%, at 20-80% and at <20% of visits, respectively. Cox regression models were used to analyse mortality risk and mixed effect models to describe trajectories of FVC and diffusing capacity for carbon monoxide (DLCO) %-predicted stratified by inflammation and immunosuppressive treatment. RESULTS: 2971 patients with SSc and 1171 patients with SSc-ILD had at least three CRP measurements available. Patients with SSc-ILD with a persistent inflammatory phenotype had a 6.7 times higher risk of mortality within 5 years compared with those with a persistent non-inflammatory phenotype (95% CI 3 to 15). In the inflammatory phenotype, FVC %-predicted was declining without (-1.11 (95% CI -2.14 to -0.08)/year), but stable with immunosuppressive treatment (-0.00 (95% CI -0.92 to 0.92)/year). In the non-inflammatory phenotype, patients with and without immunosuppressive treatment had a significant decline in FVC %-predicted, which was more pronounced in those with immunosuppressive treatment (-1.26 (95% CI -1.87 to -0.64) and -0.84 (95% CI -1.35 to -0.33)/year, respectively). CONCLUSIONS: Phenotyping by persistent inflammation provides valuable prognostic information, independent of demographics, disease duration, cutaneous subtype, treatment and SSc-ILD severity. The findings from this study support early immunosuppressive treatment in patients with SSc-ILD with persistent inflammation.

Effect of the Functional VP1 Unique Region of Human Parvovirus B19 in Causing Skin Fibrosis of Systemic Sclerosis.

Human parvovirus B19 (B19V) is a single-stranded non-enveloped DNA virus of the family Parvoviridae that has been associated with various autoimmune disorders. Systemic sclerosis (SSc) is an autoimmune connective tissue disorder with high mortality and has been linked to B19V infection. However, the precise mechanism underlying the B19V contribution to the development of SSc remains uncertain. This study investigated the impacts of the functional B19V-VP1 unique region (VP1u) in macrophages and bleomycin (BLE)-induced SSc mice. Cell experimental data showed that significantly decreased viability and migration of both B19V-VP1u-treated U937 and THP-1 macrophages are detected in the presence of celastrol. Significantly increased MMP9 activity and elevated NF-kB, MMP9, IL-6, TNF-α, and IL-1ß expressions were detected in both B19V-VP1u-treated U937 and THP-1 macrophages. Conversely, celastrol revealed an inhibitory effect on these molecules. Notably, celastrol intervened in this pathogenic process by suppressing the sPLA2 activity of B19V-VP1u and subsequently reducing the inflammatory response. Notably, the administration of B19V-VP1u exacerbated BLE-induced skin fibrosis in mice, with augmented expressions of TGF-ß, IL-6, IL-17A, IL-18, and TNF-α, ultimately leading to α-SMA and collagen I deposits in the dermal regions of BLE-induced SSc mice. Altogether, this study sheds light on parvovirus B19 VP1u linked to scleroderma and aggravated dermal fibrosis.

ACSL4 inhibition prevents macrophage ferroptosis and alleviates fibrosis in bleomycin-induced systemic sclerosis model.

BACKGROUND: Systemic sclerosis (SSc), with unclear pathophysiology, is a paradigmatic rheumatic disease of immunity dysfunction-driven multi-organ inflammation and ultimate fibrosis. Pathogenesis breakthroughs are urgently needed for available treatments halting its unremitting stiffness. This study aims to investigate whether ferroptosis can regulate the progressive SSc fibrosis. METHODS: In vivo, bleomycin (BLM)-induced mice model was subjected to ferroptosis detection using western blotting, malondialdehyde (MDA), and glutathione (GSH) assays. Pharmacological inhibitor of the acyl-CoA synthetase long-chain family member 4 (ACSL4) was utilized to explore its potential therapeutic effects for fibrosis, from histological, biochemical, and molecular analyses. In vitro, bone marrow-derived macrophages (BMDM) were activated into inflammatory phenotype and then the relationship was evaluated between activation level and ferroptosis sensitivity in lipopolysaccharide (LPS) incubation with gradient concentrations. The potential calpain/ACSL4 axis was analyzed after calpain knockdown or over-expression in Raw264.7. RESULTS: Both skin and lung tissue ferroptosis were present in SSc mice with enhanced ACSL4 expression, while ACSL4 inhibition effectively halted fibrosis progressing and provides protection from inflammatory milieu. Meanwhile, a positive regulation relationship between LPS-induced macrophage activity and ferroptosis sensitivity can be observed. After calpain knockdown, both inflammatory macrophage ferroptosis sensitivity and ACSL4 expression decreased, while its over-expression renders ACSL4-envoking condition. Also, calpain pharmacological inhibition reduced both ferroptosis and fibrosis aptitude in mice. CONCLUSIONS: ACSL4 induces inflammatory macrophage ferroptosis to aggravate fibrosis progressing. ACSL4 and its upregulators of calpains may be potential therapeutic targets for BLM model of SSc.

Intravenous immunoglobulins improve skin fibrosis in experimental models of systemic sclerosis.

Systemic sclerosis (SSc) is the most severe systemic autoimmune disease with currently no cure. Intravenous immunoglobulins (IVIg) are an attractive candidate in this disease to counteract inflammation and fibrosis but data are scarce and conflicting. This study, assessed the effects of IVIg in a murine HOCl-induced model of SSc. We showed that IVIg prevented skin inflammation and fibrosis, by mitigating the immune cell infiltration (p = 0.04), proinflammatory cytokines gene overexpression (IL1ß, p = 0.04; TNFα, p = 0.04; IL6, p = 0.05), skin and dermal thickening (p = 0.003 at d21 and p = 0.0003 at d42), the expression markers of fibrosis, such as αSMA (p = 0.031 for mRNA and p = 0.05 for protein), collagen (p = 0.05 for mRNA and p = 0.04 for protein, p = 0.05 for the hydroxyproline content) and fibronectin (p = 0.033 for mRNA). Moreover, IVIg prevented HOCl-induced alterations in splenic cell homeostasis. When administered in curative mode, despite their ability to reduce skin and dermal thickness (p < 0.0001 and p = 0.0002), IVIg showed partial or more mixed effects on skin inflammation and established fibrosis. These data favor further clinical trials in SSc patients on the potential efficiency of early and/or repeated IVIg administration.

Lead generation from N-[benzyl(4-phenylbutyl)carbamoyl]amino acid as a novel LPA1 antagonist for the treatment of systemic sclerosis.

Lysophosphatidic acid (LPA), a bioactive phospholipid, binds to the G protein-coupled LPA1 receptor on the surfaces of immune cells, to promote progression of fibrosis of the skin and organs through inducing infiltration of immune cells into tissues, chemokine production, inflammatory cytokine production, and fibroblast transformation. Anti-fibrotic effects of LPA1 blockade have been reported in animal models of scleroderma and scleroderma patients. In the study reported herein, we identified the novel urea compound 5 as a hit compound with LPA1 antagonist activity from our in-house library and synthesized the lead compound TP0541640 (18) by structural transformation utilizing a structure-based drug design (SBDD) approach. Compound 18 possessed potent in vitro LPA1 antagonist activity and exhibited a dose-dependent inhibitory effect against LPA-induced histamine release in mice. Furthermore, 18 significantly suppressed collagen production and skin thickening in a mouse model of bleomycin-induced skin fibrosis. Herein, we describe the compound design strategies and in vivo studies in greater detail.

A cysteine proteinase inhibitor ALLN alleviates bleomycin-induced skin and lung fibrosis.

BACKGROUND: Systemic sclerosis (SSc) is a connective tissue disease that is characterized by fibrosis in the skin and internal organs, such as the lungs. Activated differentiation of progenitor cells, which are mainly resident fibroblasts, into myofibroblasts is considered a key mechanism underlying the overproduction of extracellular matrix and the resultant tissue fibrosis in SSc. Calpains are members of the Ca2+-dependent cysteine protease family, whose enzymatic activities participate in signal transduction and tissue remodeling, potentially contributing to fibrosis in various organs. However, the roles of calpain in the pathogenesis of SSc remain unknown. This study aimed to examine the anti-fibrotic properties of N-acetyl-Leu-Leu-norleucinal (ALLN), one of the cysteine proteinase inhibitors that primarily inhibit calpain, in vitro and in vivo, to optimally translate into the therapeutic utility in human SSc. METHODS: Normal human dermal and lung fibroblasts pretreated with ALLN were stimulated with recombinant transforming growth factor beta 1 (TGF-ß1), followed by assessment of TGF-ß1/Smad signaling and fibrogenic molecules. RESULTS: ALLN treatment significantly inhibited TGF-ß1-induced phosphorylation and nuclear transport of Smad2/3 in skin and lung fibroblasts. TGF-ß1-dependent increases in α-smooth muscle actin (αSMA), collagen type I, fibronectin 1, and some mesenchymal transcription markers were attenuated by ALLN. Moreover, our findings suggest that ALLN inhibits TGF-ß1-induced mesenchymal transition in human lung epithelial cells. Consistent with these in vitro findings, administering ALLN (3 mg/kg/day) three times a week intraperitoneally remarkably suppressed the development of skin and lung fibrosis in a SSc mouse model induced by daily subcutaneous bleomycin injection. The number of skin- and lung-infiltrating CD3+ T cells decreased in ALLN-treated mice compared with that in control-treated mice. Phosphorylation of Smad3 and/or an increase in αSMA-positive myofibroblasts was significantly inhibited by ALLN treatment on the skin and lungs. However, no adverse effects were observed. CONCLUSIONS: Our results prove that calpains can be a novel therapeutic target for skin and lung fibrosis in SSc, considering its inhibitor ALLN.