Mouse Model Of Systemic Sclerosis Research Articles

PLG nanoparticles target fibroblasts and MARCO+ monocytes to reverse multiorgan fibrosis.

Systemic sclerosis (SSc) is a chronic, multisystem orphan disease with a highly variable clinical course, high mortality rate, and a poorly understood complex pathogenesis. We have identified an important role for a subpopulation of monocytes and macrophages characterized by surface expression of the scavenger receptor macrophage receptor with collagenous structure (MARCO) in chronic inflammation and fibrosis in SSc and in preclinical disease models. We show that MARCO+ monocytes and macrophages accumulate in lesional skin and lung in topographic proximity to activated myofibroblasts in patients with SSc and in the bleomycin-induced mouse model of SSc. Short-term treatment of mice with a potentially novel nanoparticle, poly(lactic-co-glycolic) acid (PLG), which is composed of a carboxylated, FDA-approved, biodegradable polymer and modulates activation and trafficking of MARCO+ inflammatory monocytes, markedly attenuated bleomycin-induced skin and lung inflammation and fibrosis. Mechanistically, in isolated cells in culture, PLG nanoparticles inhibited TGF-dependent fibrotic responses in vitro. Thus, MARCO+ monocytes are potent effector cells of skin and lung fibrosis and can be therapeutically targeted in SSc using PLG nanoparticles.

Tofacitinib and metformin reduce the dermal thickness and fibrosis in mouse model of systemic sclerosis

Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway is important in the process of inflammation and fibrosis. The adenosine 5′-monophosphate-activated protein kinase (AMPK) enzyme can affect JAK/STAT pathway. Tofacitinib is a pan-JAK inhibitör. Metformin activates AMPK enzyme. We aimed to investigate the therapeutic efficacy of tofacitinib and metformin on IL-17 and TGF-β cytokines, skin fibrosis and inflammation in mouse model of systemic sclerosis (SSc). 40 Balb/c female mice were divided into 4 groups: (control, sham (BLM), tofacitinib and metformin). The mice in the tofacitinib group received oral tofacitinib (20 mg/kg/daily) and mice in the metformin group received oral metformin (50 mg/kg/day) for 28 days. At the end of 4th week, all groups of mice were decapitated and tissue samples were taken for analysis. Histopathological analysis of skin tissue was performed, and mRNA expressions of collagen 3A, IL-17 and TGF-β were assessed by real-time PCR and ELISA. Repeated BLM injections had induced dermal fibrosis. Moreover, the tissue levels of collagen 3A, IL-17 and TGF-β were elevated in the BLM group. Tofacitinib and metformin mitigated dermal fibrosis. They reduced dermal thickness and tissue collagen 3A, IL-17 and TGF-β levels. Tofacitinib and metformin demonstrated anti-inflammatory and anti-fibrotic effects in the mouse model of SSc.

Linagliptin ameliorates pulmonary fibrosis in systemic sclerosis mouse model via inhibition of endothelial-to-mesenchymal transition.

Systemic sclerosis (SSc) is a connective tissue disease that often causes pulmonary fibrosis. Dipeptidyl peptidase 4 (DPP4) inhibitor has shown anti-fibrotic properties in various fibrotic diseases. However, only two studies have reported its anti-fibrosis effects in pulmonary fibrosis, and the mechanism is not completely clear. In the present study, we further investigated the protective effects of linagliptin, a highly specific DPP4 inhibitor, on pulmonary fibrosis in SSc mouse model and the potential mechanisms. The results showed that linagliptin ameliorated pulmonary fibrosis in SSc mouse model, as evidenced by improved pathological changes of lung and body weight loss induced by BLM. Linagliptin also reduced BLM-induced oxidative stress, inflammation in lung in vivo. We revealed that linagliptin attenuated BLM-induced endothelial-to-mesenchymal transition (EndMT) in vitro and in vivo. BLM-induced enhanced migration ability of endothelial cells was also alleviated by linagliptin. Moreover, we confirmed that the Akt/mammalian target of rapamycin pathway was involved in BLM-induced EndMT in vivo, which was suppressed by linagliptin. In summary, we further confirmed the therapeutic effects of linagliptin on pulmonary fibrosis in SSc mouse model, which is based on its inhibitory effects on EndMT, oxidative stress, and inflammation.

Therapeutic effects of adipose-derived mesenchymal stem/stromal cells with enhanced migration ability and hepatocyte growth factor secretion by low-molecular-weight heparin treatment in bleomycin-induced mouse models of systemic sclerosis

BackgroundAdipose-derived mesenchymal stem cells (ASCs) have gained attention as a new treatment for systemic sclerosis (SSc). Low-molecular-weight heparin (LMWH) enhances cell function and stimulates the production of hepatocyte growth factor (HGF) in a variety of cells. This study investigated the effects of LMWH on the functions of mouse ASCs (mASCs), and the therapeutic effects of mASCs activated with LMWH (hep-mASCs) in mouse models of SSc.MethodsThe cellular functions of mASCs cultured with different concentrations of LMWH were determined. Mice were divided into four groups: bleomycin (BLM)-induced SSc (BLM-alone), BLM-induced SSc administered with mASCs (BLM-mASC), and BLM-induced SSc administered with mASCs activated with 10 or 100 μg/mL LMWH (BLM-hep-mASC); there were 9 mice per group (n = 9). Skin inflammation and fibrosis were evaluated using histological and biochemical examinations and gene expression levels.ResultsIn vitro assays showed that migration ability and HGF production were significantly higher in hep-mASCs than in mASCs alone. The mRNA expression levels of cell migration factors were significantly upregulated in hep-mASCs compared to those in mASCs alone. The hep-mASCs accumulated in the skin tissues more than mASCs alone. The thickness of skin and hydroxyproline content in BLM-hep-mASC groups were significantly decreased, and the skin mRNA expression levels of interleukin-2, α-smooth muscle actin, transforming growth factor β1, collagen type 1 alpha 1, and tissue inhibitor of metalloproteinase 2 were significantly downregulated compared to those in the BLM-alone group.Conclusionshep-mASCs showed higher anti-inflammatory and anti-fibrotic effects than mASCs alone and may be a promising candidate for SSc treatment.

Progesterone Aggravates Lung Fibrosis in a Mouse Model of Systemic Sclerosis.

BackgroundGender-related factors have explained the higher prevalence of autoimmune diseases in women. Sex hormones play a key role in the immune system and parenchymal cells function; therefore, these hormones can be important in the pathogenesis of autoimmune diseases as a risk or beneficial factor. Lung fibrosis is the main cause of mortality in systemic sclerosis, a female predominant autoimmune disease. The objective of this study was to examine the effect of progesterone on lung fibrosis in a mouse model of systemic sclerosis.MethodsMice with bleomycin-induced lung fibrosis treated with progesterone subcutaneously for 21 and 28 days. Blood was collected for hormone and cytokine measurement at the end of treatment then, skin and lung tissues were harvested for histological assessment, gene expression, cytokine, hydroxyproline, and gelatinase measurement.ResultsTrichrome staining and hydroxyproline measurements showed that progesterone treatment increased the content of collagen in fibrotic and normal lung tissues. Progesterone increased α-SMA (P < 0.01), TGF- β (P < 0.05) and decreased MMP9 (P < 0.05) in fibrotic lung tissues. Also progesterone treatment decreased the gene expression of Col1a2 (P <0.05), Ctgf (P <01), End1 (0.001) in bleomycin- injured lung tissues. The serum level of TNF-α was decreased, but the serum level of cortisol was increased by progesterone treatment in fibrotic mice (P< 0.05).ConclusionOur results showed that progesterone aggravates lung fibrosis in a mouse model of systemic sclerosis.

Mirodenafil ameliorates skin fibrosis in bleomycin-induced mouse model of systemic sclerosis

ABSTRACT Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by fibrosis of the skin and internal organs. Despite the recent advances in the pathogenesis and treatment of SSc, effective therapies for fibrosis caused by SSc have not yet been established. In this study, we investigated the potential role of mirodenafil, a potent phosphodiesterase 5 (PDE5) inhibitor, in the treatment of fibrosis in SSc. We used a bleomycin (BLM)-induced SSc mouse model to mimic the typical features of fibrosis in human SSc and examined the dermal thickness to assess the degree of skin fibrosis after staining with hematoxylin and eosin or Masson’s trichrome stains. The effect of mirodenafil on the expression of profibrotic genes was also analyzed by treating fibroblasts with transforming growth factor (TGF)-β and mirodenafil. We showed that mirodenafil ameliorated dermal fibrosis and downregulated the protein levels of fibrosis markers including COL1A1 and α-SMA in the BLM-induced SSc mouse model. Further, using mouse embryonic fibroblasts and human lung fibroblasts, we demonstrated that the expression of collagen and profibrotic genes was reduced by treatment with mirodenafil. Finally, we showed that mirodenafil inhibited TGF-β-induced phosphorylation of Smad2/3 in fibroblasts, which suggested that this drug may ameliorate fibrosis by suppressing the TGF-β/Smad signaling pathway. Our findings suggest that mirodenafil possesses a therapeutic potential for treating fibrosis in SSc.

Interleukin-31 promotes fibrosis and T helper 2 polarization in systemic sclerosis

Systemic sclerosis (SSc) is a chronic multisystem disorder characterized by fibrosis and autoimmunity. Interleukin (IL)-31 has been implicated in fibrosis and T helper (Th) 2 immune responses, both of which are characteristics of SSc. The exact role of IL-31 in SSc pathogenesis is unclear. Here we show the overexpression of IL-31 and IL-31 receptor A (IL-31RA) in dermal fibroblasts (DFs) from SSc patients. We elucidate the dual role of IL-31 in SSc, where IL-31 directly promotes collagen production in DFs and indirectly enhances Th2 immune responses by increasing pro-Th2 cytokine expression in DFs. Furthermore, blockade of IL-31 with anti-IL-31RA antibody significantly ameliorates fibrosis and Th2 polarization in a mouse model of SSc. Therefore, in addition to defining IL-31 as a mediator of fibrosis and Th2 immune responses in SSc, our study provides a rationale for targeting the IL-31/IL-31RA axis in the treatment of SSc.

003 Anti-fractalkine monoclonal antibody therapy ameliorates murine sclerodermatous chronic graft-versus-host disease

Systemic sclerosis (SSc) is an autoimmune disease characterized by fibrosis and vascular injury of skin and internal organs. Fractalkine (CX3CL1) is a chemokine that is expressed on vascular endothelial cells and functions as an adhesion molecule for CX3CR1-positive leukocytes. Additionally, soluble fractalkine is involved in the migration of CX3CR1-expressing leukocytes into the lesional tissue. We previously reported that the expression of fractalkine and its receptor CX3CR1 was both augmented in SSc patients, and anti-mouse fractalkine monoclonal antibody (mAb) suppressed inflammation, fibrosis, and vascular injury of the skin in bleomycin- or TGF-β/CTGF-induced SSc mouse models.

B Cell Depletion Inhibits Fibrosis via Suppression of Profibrotic Macrophage Differentiation in a Mouse Model of Systemic Sclerosis.

We undertook this study to investigate the effect of B cell depletion on fibrosis in systemic sclerosis (SSc) and its mechanism of action. Mice with bleomycin-induced SSc (BLM-SSc) were treated with anti-CD20 antibody, and skin and lung fibrosis were histopathologically evaluated. T cells and macrophages were cocultured with B cells, and the effect of B cells on their differentiation was assessed by flow cytometry. We also cocultured B cells and monocytes from SSc patients and analyzed the correlation between fibrosis and profibrotic macrophage induction by B cells. B cell depletion inhibited fibrosis in mice with BLM-SSc. B cells from mice with BLM-SSc increased proinflammatory cytokine-producing T cells in coculture. In mice with BLM-SSc, B cell depletion before BLM treatment (pre-depletion) inhibited fibrosis more strongly than B cell depletion after BLM treatment (post-depletion) (P < 0.01). However, the frequencies of proinflammatory T cells were lower in the post-depletion group than in the pre-depletion group. This discrepancy suggests that the effect of B cell depletion on fibrosis cannot be explained by its effect on T cell differentiation. On the other hand, profibrotic macrophages were markedly decreased in the pre-depletion group compared to the post-depletion group (P < 0.05). Furthermore, B cells from mice with BLM-SSc increased profibrotic macrophage differentiation in coculture (P < 0.05). In SSc patients, the extent of profibrotic macrophage induction by B cells correlated with the severity of fibrosis (P < 0.0005). These findings suggest that B cell depletion inhibits tissue fibrosis via suppression of profibrotic macrophage differentiation in mice with BLM-SSc, providing a new rationale for B cell depletion therapy in SSc.

The pan-PPAR agonist lanifibranor reduces development of lung fibrosis and attenuates cardiorespiratory manifestations in a transgenic mouse model of systemic sclerosis

BackgroundThe TβRII∆k-fib transgenic (TG) mouse model of scleroderma replicates key fibrotic and vasculopathic complications of systemic sclerosis through fibroblast-directed upregulation of TGFβ signalling. We have examined peroxisome proliferator-activated receptor (PPAR) pathway perturbation in this model and explored the impact of the pan-PPAR agonist lanifibranor on the cardiorespiratory phenotype.MethodsPPAR pathway gene and protein expression differences from TG and WT sex-matched littermate mice were determined at baseline and following administration of one of two doses of lanifibranor (30 mg/kg or 100 mg/kg) or vehicle administered by daily oral gavage up to 4 weeks. The prevention of bleomycin-induced lung fibrosis and SU5416-induced pulmonary hypertension by lanifibranor was explored.ResultsGene expression data were consistent with the downregulation of the PPAR pathway in the TβRII∆k-fib mouse model. TG mice treated with high-dose lanifibranor demonstrated significant protection from lung fibrosis after bleomycin and from right ventricular hypertrophy following induction of pulmonary hypertension by SU5416, despite no significant change in right ventricular systolic pressure.ConclusionsIn the TβRII∆k-fib mouse strain, treatment with 100 mg/kg lanifibranor reduces the development of lung fibrosis and right ventricular hypertrophy induced by bleomycin or SU5416, respectively. Reduced PPAR activity may contribute to the exaggerated fibroproliferative response to tissue injury in this transgenic model of scleroderma and its pulmonary complications.

Antifibrotic effects and mechanisms of mesenchymal stem cell-derived exosomes in a systemic sclerosis mouse model: Possible contribution of miR-196b-5p

BackgroundSystemic sclerosis (SSc) is a connective tissue disorder characterized by the development of fibrosis in the skin and internal organs. Increasing evidence suggests that mesenchymal stem cells (MSCs) can be used to a treatment for fibrotic diseases. Recent studies have demonstrated that some of the biological effects of MSCs are due to the secretion of exosomes. However, the precise mechanisms underlying MSCs-derived exosomes in skin fibrosis are not well understood. ObjectiveWe aimed to elucidate the effect of MSCs-derived exosomes on skin fibrosis in SSc and the mechanism underlying their inhibitory action on fibrosis. MethodsExosome was collected from MSCs by ultracentrifugation method. We examined the suppressive effect of MSCs-derived exosome on skin fibrosis in bleomycin-induced SSc mouse model. Skin samples from the injected site were collected for further examination, and micro-RNA analysis of MSCs-derived exosome was performed. ResultsInjection of MSCs-derived exosomes significantly inhibited bleomycin-induced dermal fibrosis in mice. MSCs-derived exosomes significantly reduced the amount of collagen and the number of α-SMA+ myofibroblasts and CD68+ macrophages in lesional skin. They also reduced the expression of type I collagen and TGF-β receptor 1 in fibroblasts in vitro. Moreover, micro-RNA analysis revealed that several microRNAs in MSCs-derived exosomes have antifibrotic potential. We confirmed that overexpression of miR-196b-5p in fibroblasts significantly suppressed collagen type I alpha 2 expression. ConclusionThis study demonstrated that inhibition of collagen type I expression by miR-196b-5p in exosomes might be one of the mechanisms by which MSCs suppress skin fibrosis in an SSc mouse model.

TGFβ promotes low IL10-producing ILC2 with profibrotic ability involved in skin fibrosis in systemic sclerosis

ObjectiveInnate lymphoid cells-2 (ILC2) were shown to be involved in the development of lung or hepatic fibrosis. We sought to explore the functional and phenotypic heterogeneity of ILC2 in skin...

Bone morphogenetic protein-7 inhibits endothelial-to-mesenchymal transition in primary human umbilical vein endothelial cells and mouse model of systemic sclerosis via Akt/mTOR/p70S6K pathway

BackgroundSystemic sclerosis (SSc) is an autoimmune inflammatory and vascular disorder that causes tissue fibrosis of the skin and internal organs. Endothelial-to-mesenchymal transition (EndoMT) has been considered an important mechanism in the pathogenesis of vascular remodeling in SSc. Recent studies suggested that bone morphogenic protein 7 (BMP-7) has anti-fibrotic effects in several fibrotic diseases. ObjectivesTo investigate the mechanism of BMP-7 in inhibiting TGF-β-induced EndoMT in systemic sclerosis (SSc). MethodsSkin tissues of both healthy controls and SSc patients were detected the distribution of BMP-7. TGF-β was applied to induce the EndoMT model of human umbilical vein endothelial cells (HUVECs), and bleomycin was used to established the SSc mouse model. After treatment of BMP-7, the protein levels of endothelial specific markers, mesenchymal cell products, transcription factors and Akt signal pathway were examined by western blotting, immunofluorescence or immunohistochemistry both in vivo and in vitro. ResultsThe expression of BMP-7 was decreased in the basal layer of epidermis and dermis of SSc patients. EndoMT in TGF-β-treated HUVECs and skins of SSc mouse model were markedly attenuated after treatment with rh-BMP-7. Moreover, Akt/mTOR/p70S6K phosphorylation was involved in EndoMT and BMP-7 suppressed TGF-β- or bleomycin-induced theses phosphorylation in HUVECs or SSc mouse model. ConclusionBMP-7 reduced the production of TGF-β-induced EndoMT in HUVECs and SSc mouse model through Akt/mTOR/p70S6K signaling pathway. These findings suggested that BMP-7 could be employed as a promising antifibrotic therapy for SSc.

Fli1 deficiency suppresses RALDH1 activity of dermal dendritic cells and related induction of regulatory T cells: a possible role in scleroderma

BackgroundAldehyde dehydrogenase 1 family member A1 (RALDH1)-producing dermal dendritic cells (DCs), a conventional DC subset regulating skin fibrosis, are decreased in the involved skin of patients with systemic sclerosis (SSc). In this study, we investigated the contribution of Fli1 deficiency, a potential predisposing factor of SSc, to the phenotypical alteration of RALDH1-producing dermal DCs by using SSc model mice and SSc skin samples.MethodsBleomycin (BLM)-induced skin fibrosis was generated with Fli1+/− and wild-type mice. The proportions of DC and CD4+ T cell subsets were determined by flow cytometry in the dermis of BLM-treated mice. Fli1 expression in dermal DCs was evaluated by immunofluorescence with skin samples of SSc and healthy control subjects.ResultsRALDH activity of dermal DCs was significantly decreased in BLM-treated Fli1+/− mice compared with BLM-treated wild-type mice, whereas the proportion of CD103−CD11b− dermal DCs, a major DC subset producing RALDH1 in response to BLM injection, was comparable between groups. Relevant to this finding, the proportion of regulatory T cells (Tregs) in the dermis was decreased in BLM-treated Fli1+/− mice relative to BLM-treated wild-type mice, while the proportions of Th1, Th2 and Th17 cells were unaltered. In the involved skin of SSc patients, Fli1 was downregulated in CD11c+ cells, including dermal DCs.ConclusionsFli1 deficiency inhibits RALDH1 activity of CD103−CD11b− dermal DCs and related induction of Tregs in BLM-treated mice. Considering Fli1 reduction in SSc dermal DCs, Fli1deficiency may impair the dermal DC-Treg system, contributing to the development of skin fibrosis in SSc.

Soluble guanylate cyclase stimulator reduced the gastrointestinal fibrosis in bleomycin-induced mouse model of systemic sclerosis

BackgroundSystemic sclerosis (SSc) is a chronic autoimmune-mediated connective tissue disorder. Although the etiology of the disease remains undetermined, SSc is characterized by fibrosis and proliferative vascular lesions of the skin and internal organs. SSc involves the gastrointestinal tract in more than 90 % of patients. Soluble guanylate cyclase (sGC) stimulator is used to treat pulmonary artery hypertension (PAH) and has been shown to inhibit experimental skin fibrosis.MethodsFemale C57BL/6J mice were treated with BLM or normal saline by subcutaneous implantation of osmotic minipump. These mice were sacrificed on day 28 or day 42. Gastrointestinal pathologies were examined by Masson Trichrome staining. The expression of fibrosis-related genes in gastrointestinal tract was analyzed by real-time PCR, and the levels of collagen in the tissue were measured by Sircol collagen assay. To evaluate peristaltic movement, the small intestinal transport (ITR%) was calculated as [dyeing distance × (duodenum − appendix)] − 1 × 100 (%). We treated BLM-treated mice with sGC stimulator or DMSO orally and analyzed them on day 42.ResultsHistological examination revealed that fibrosis from lamina propria to muscularis mucosa in the esophagus was significantly increased in BLM-treated mice, suggesting that BLM induces esophageal hyperproliferative and prefibrotic response in C57BL/6J mice. In addition, the gene expression levels of Col3a1, CCN2, MMP-2, MMP-9, TIMP-1, and TIMP-2 in the esophagus were significantly increased in BLM-treated mice. More severe hyperproliferative and prefibrotic response was observed in the mice sacrificed on day 42 than the mice sacrificed on day 28. The ITR% was found to be significantly lower in BLM-treated mice, suggesting that gastrointestinal peristaltic movement was reduced in BLM-treated mice. Furthermore, we demonstrated that sGC stimulator treatment significantly reduced hyperproliferative and prefibrotic response of esophagus and intestine in BLM-treated mice, by histological examination and Sircol collagen assay.ConclusionsThese findings suggest that BLM induces gastrointestinal hyperproliferative and prefibrotic response in C57BL/6J mice, and treatment with sGC stimulator improves the BLM-induced gastrointestinal lesion.

MicroRNA-30c attenuates fibrosis progression and vascular dysfunction in systemic sclerosis model mice.

Systemic sclerosis (SSc) is characterized by peripheral circulatory disturbance and fibrosis in skin and visceral organs. We recently demonstrated that α2-antiplasmin (α2AP) is elevated in SSc dermal fibroblasts and SSc model mice, and is associated with fibrosis progression and vascular dysfunction. In the present study, we predicted that α2AP could be a target of microRNA-30c (miR-30c) using TargetScan online database, and investigated the effect of miR-30c on the pathogenesis of SSc using a bleomycin-induced SSc model mice. miR-30c attenuated α2AP expression, and prevented the pro-fibrotic changes (increased dermal thickness, collagen deposition, myofibroblast accmulation) and the vascular dysfunction (the reduction of vascular endothelial cells (ECs) and blood flow) in the skin of SSc model mice. Furthermore, miR-30c suppressed pulmonary fibrosis progression in the SSc model mice. miR-30c exerts the anti-fibrotic and anti-angiopathy effects on SSc model mice, and might provide a basis for clinical strategies for SSc.

Butyrate Improves Skin/Lung Fibrosis and Intestinal Dysbiosis in Bleomycin-Induced Mouse Models.

Systemic sclerosis (SSc) is an autoimmune disorder characterized by fibrosis of the skin and internal organs. Despite several studies on SSc treatments, effective treatments for SSc are still lacking. Since evidence suggests an association between intestinal microbiota and SSc, we focused on butyrate, which has beneficial effects in autoimmune diseases as a bacterial metabolite. Here, we investigated the therapeutic potential of sodium butyrate (SB) using a bleomycin-induced fibrosis mouse model of SSc and human dermal fibroblasts (HDFs). SB attenuated bleomycin-induced dermal and lung fibrosis in mice. SB influenced fecal microbiota composition (phyla Actinobacteria and Bacteroidetes, genera Bifidobacterium and Ruminococcus_g2). SB controlled macrophage differentiation in mesenteric lymph nodes, spleen, and bronchoalveolar lavage cells of mice with bleomycin-induced skin fibrosis. Profibrotic and proinflammatory gene expression was suppressed by SB administration in skin. Furthermore, SB inhibited transforming growth factor β1-responsive proinflammatory expression with increased acetylation of histone 3 in HDFs. Subcutaneous SB application had antifibrogenic effects on the skin. Butyrate ameliorated skin and lung fibrosis by improving anti-inflammatory activity in a mouse model of SSc. Butyrate may exhibit indirect and direct anti-fibrogenic action on fibroblasts by regulating macrophage differentiation and inhibition of histone deacetylase 3. These findings suggest butyrate as an SSc treatment.

Mouse Models of Skin Fibrosis.

Systemic sclerosis (SSc) is a rare systemic autoimmune disease associated with a high mortality. The first histopathological hallmarks are vasculopathy and inflammation, followed by fibrosis of the skin and internal organs. The molecular and cellular mechanisms are incompletely understood. Rodent models provide important insights into the pathogenesis of SSc and are a mainstay for the development of novel targeted therapies. Here we describe the mechanistic insights of inducible and genetic models, and also discuss in detail the limitations and pitfalls of the most frequently used SSc mouse models. We also describe protocols for running the established bleomycin-induced scleroderma skin fibrosis model.

From a Designer Drug to the Discovery of Selective Cannabinoid Type 2 Receptor Agonists with Favorable Pharmacokinetic Profiles for the Treatment of Systemic Sclerosis.

Synthetic cannabinoids, as exemplified by SDB-001 (1), bind to both CB1 and CB2 receptors and exert cannabimimetic effects similar to (-)-trans-Δ9-tetrahydrocannabinol, the main psychoactive component present in the cannabis plant. As CB1 receptor ligands were found to have severe adverse psychiatric effects, increased attention was turned to exploiting the potential therapeutic value of the CB2 receptor. In our efforts to discover novel and selective CB2 receptor agonists, 1 was selected as a starting point for hit molecule identification and a class of 1H-pyrazole-3-carboxamide derivatives were thus designed, synthesized, and biologically evaluated. Systematic structure-activity relationship investigations resulted in the identification of the most promising compound 66 as a selective CB2 receptor agonist with favorable pharmacokinetic profiles. Especially, 66 treatment significantly attenuated dermal inflammation and fibrosis in a bleomycin-induced mouse model of systemic sclerosis, supporting that CB2 receptor agonists might serve as potential therapeutics for treating systemic sclerosis.

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

BackgroundJanus 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. ObjectiveTo evaluate the effect of tofacitinib on the modulation of cytokine-producing T and B cells, and proinflammatory cells in a mouse model of SSc. MethodsBleomycin (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. ResultsTofacitinib 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. ConclusionThese 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.