Pathogenesis of systemic sclerosis: altered B cell function is the key linking systemic autoimmunity and tissue fibrosis

Sesamol attenuates bleomycin-induced pulmonary toxicity and fibrosis in experimental animals

Sesamol, a lignan obtained from roasted seeds of Sesamum indicum, has high antioxidant and anti-inflammatory activity. In this study, we have investigated the effect of sesamol on Bleomycin (BLM) induced pulmonary toxicity as well as fibrosis in Wistar rats. Lung toxicity was induced by administration of BLM, 0.015 U/g ip, twice weekly for 28 days whereas lung fibrosis was induced by BLM, 0.015 U/g ip, every 5th day for 49 days. Sesamol administration was started 7 days before first dose of BLM in both the models. It was observed that sesamol 50 mg/kg most effectively attenuated pulmonary toxicity by reducing oxidative stress, inflammation and apoptosis. This dose was further evaluated for its anti-fibrotic effect. It was observed that there was a significant reduction in fibrosis. Lung collagen content was markedly reduced. Furthermore, expression of pro-fibrotic proteins, TGF-β/SMAD and α-SMA, was reduced and that of anti-fibrotic protein, AMPK, was markedly increased. Even though the combination of sesamol with pirfenidone exhibited no additional protection than either drug alone, it is evident from our study that our test drug, sesamol is comparable in efficacy to pirfenidone. Thus, sesamol has promising therapeutic potential in treatment of pulmonary toxicity and fibrosis.

Host-Derived Cytotoxic Agents in Chronic Inflammation and Disease Progression

At inflammatory sites, cytotoxic agents are released and generated from invading immune cells and damaged tissue cells. The further fate of the inflammation highly depends on the presence of antagonizing principles that are able to inactivate these host-derived cytotoxic agents. As long as the affected tissues are well equipped with ready-to-use protective mechanisms, no damage by cytotoxic agents occurs and resolution of inflammation is initiated. However, long-lasting and severe immune responses can be associated with the decline, exhaustion, or inactivation of selected antagonizing principles. Hence, cytotoxic agents are only partially inactivated and contribute to damage of yet-unperturbed cells. Consequently, a chronic inflammatory process results. In this vicious circle of permanent cell destruction, not only novel cytotoxic elements but also novel alarmins and antigens are liberated from affected cells. In severe cases, very low protection leads to organ failure, sepsis, and septic shock. In this review, the major classes of host-derived cytotoxic agents (reactive species, oxidized heme proteins and free heme, transition metal ions, serine proteases, matrix metalloproteases, and pro-inflammatory peptides), their corresponding protective principles, and resulting implications on the pathogenesis of diseases are highlighted.

Safety and Efficacy of B-Cell Depletion with Rituximab for the Treatment of Systemic Sclerosis-associated Pulmonary Arterial Hypertension: A Multicenter, Double-Blind, Randomized, Placebo-controlled Trial

Rationale: Systemic sclerosis (SSc)-pulmonary arterial hypertension (PAH) is one of the most prevalent and deadly forms of PAH. B cells may contribute to SSc pathogenesis. Objectives: We investigated the safety and efficacy of B-cell depletion for SSc-PAH. Methods: In an NIH-sponsored, multicenter, double-blinded, randomized, placebo-controlled, proof-of-concept trial, 57 patients with SSc-PAH on stable-dose standard medical therapy received two infusions of 1,000 mg rituximab or placebo administered 2 weeks apart. The primary outcome measure was the change in 6-minute-walk distance (6MWD) at 24 weeks. Secondary endpoints included safety and invasive hemodynamics. We applied a machine learning approach to predict drug responsiveness. Measurements and Main Results: We randomized 57 subjects from 2010 to 2018. In the primary analysis, using data through Week 24, the adjusted mean change in 6MWD at 24 weeks favored the treatment arm but did not reach statistical significance (23.6 ± 11.1 m vs. 0.5 ± 9.7 m; P = 0.12). Although a negative study, when data through Week 48 were also considered, the estimated change in 6MWD at Week 24 was 25.5 ± 8.8 m for rituximab and 0.4 ± 7.4 m for placebo (P = 0.03). Rituximab treatment appeared to be safe and well tolerated. Low levels of RF (rheumatoid factor), IL-12, and IL-17 were sensitive and specific as favorable predictors of a rituximab response as measured by an improved 6MWD (receiver operating characteristic area under the curve, 0.88-0.95). Conclusions: B-cell depletion therapy is a potentially effective and safe adjuvant treatment for SSc-PAH. Future studies in these patients can confirm whether the identified biomarkers predict rituximab responsiveness. Clinical trial registered with www.clinicaltrails.gov (NCT01086540).

Current immunosuppressive and antifibrotic therapies of systemic sclerosis and emerging therapeutic strategies

INTRODUCTION

Systemic sclerosis (SSc) is a rare, difficult to treat disease with profound effects on quality of life and high mortality. Complex and incompletely understood pathophysiologic processes and greatly heterogeneous clinical presentations and outcomes have hampered drug development.

AREAS COVERED

This review summarizes the currently available immunosuppressive and antifibrotic therapies and discusses novel approaches for the treatment of SSc. We reviewed the literature using the MEDLINE and ClinicalTrial.gov databases between May and September 2020.

EXPERT OPINION

Available immunosuppressive and antifibrotic drugs only modestly impact the course of the disease. Most drugs are currently only investigated in the subset of patients with early diffuse cutaneous SSc. In this patient population, hematopoietic stem-cell transplantation is currently the only treatment that has demonstrated reversal of lung involvement, enhanced quality of life and reduced long-term mortality, but carries the risk of short-term treatment-related mortality. A great need to provide better therapeutic options to patients exists also for those patients who have limited cutaneous skin involvement. A better understanding of SSc pathophysiology has enabled the identification of numerous new therapeutic targets. The progress made in the design of clinical trials and outcome parameters will likely result in the improvement of effective management options.

Association between systemic sclerosis and risk of lung cancer: results from a pool of cohort studies and Mendelian randomization analysis

BACKGROUND

Population-based cohort studies have indicated that systemic sclerosis (SSc) may be associated with an increased risk of lung cancer. However, there are few studies that comprehensively investigate their correlation and the causal effect remains unknown.

METHODS

A systematic search of PubMed, Web of Science, Cochrane Library and Embase from the inception dates to December 1, 2019 was carried out. Meta-analysis was performed to calculate odds ratio (OR) and corresponding 95% confidence interval (CI) using random-effects models. Subgroup analyses were performed regarding gender. Two-sample Mendelian randomization (MR) was carried out with summary data from published genome-wide association studies of SSc (Neale Lab, 3871 individuals; UK Biobank, 463,315 individuals) and lung cancer (International Lung Cancer Consortium, 27,209 individuals; UK Biobank, 508,977 individuals). Study-specific estimates were summarized using inverse variance-weighted, weighted median, and MR-Egger method.

RESULTS

Through meta-analysis of 10 population-based cohort studies involving 12,218 patients, we observed a significantly increased risk of lung cancer among patients with SSc (OR 2.80, 95% CI 1.55-5.03). In accordance with subgroup analysis, male patients (OR 4.11, 95% CI 1.92-8.79) had a 1.5-fold higher lung cancer risk compared with female patients (OR 2.73, 95% CI 1.41-5.27). However, using a score of 11 SSc-related single nucleotide polymorphisms (p < 5*10^-8) as instrumental variables, the MR study did not support a causality between SSc and lung cancer (OR 1.001, 95% CI 0.929-1.100, p = 0.800). Specifically, subgroup MR analyses indicated that SSc was not associated with increased risks of non-small-cell lung cancer (OR 1.000, 95% CI 0.999-1.000, p = 0.974), including lung adenocarcinoma (OR 0.996, 95% CI 0.906-1.094, p = 0.927), squamous cell lung carcinoma (OR 1.034, 95% CI 0.937-1.140, p = 0.507), nor small-cell lung cancer (OR 1.000, 95% CI 0.999-1.000, p = 0.837).

CONCLUSIONS

This study indicated an increased risk of lung cancer among patients with SSc by meta-analysis, whereas the MR study did not support a causality between the two diseases. Further studies are warranted to investigate the factors underlying the attribution of SSc to lung cancer risk.

Long-term peritoneal dialysis treatment provokes activation of genes related to adaptive immunity

Permanent irritation of the peritoneum during peritoneal dialysis (PD) treatment leads to local chronic inflammation and subsequently activation of processes driving fibrogenesis in the long-term. The aim of the study was to compare the peritoneal effluent transcriptome of 20 patients treated less and 13 patients treated more than 2 years using microarray analysis. An increased expression of genes associated with an immune response was observed in long-term treated patients with well preserved peritoneal function, when compared to patients treated less than 2 years. From 100 genes highly expressed in long-term patients, a significant up-regulation of six was found by RT-qPCR: LY9 (lymphocyte antigen 9), TNSFR4 (tumor necrosis factor receptor superfamily, member 4), CD 79A (CD79a molecule), CCR7 (chemokine C-C receptor 7), CEACAM1 (carcinoembryonic antigen-related cell adhesion molecule 1) and IL2RA (interleukin 2 receptor alpha chain). Furthermore, the effluent cell population was analysed. A positive relationship between the number of granulocytes and NK cells on one hand, and duration of PD treatment on the other, was shown. We conclude, that the mechanisms of adaptive immunity promoting T helper 2 cells response are activated in the long-term before functional alterations develop. It consequently might trigger the fibrosis promoting processes.

Treatment of systemic sclerosis associated fibrotic manifestations: Current options and future directions

Systemic sclerosis (SSc) is a complicated multisystem disease which is characterized by the highest standardized mortality ratio among all systemic rheumatic diseases with no approved therapies so far. From a pathogenetic point of view it is generally considered that autoimmunity, vasculopathy and fibrosis are the main pathophysiologic processes. In this opinion article/minireview we will discuss current and future options for SSc-related fibrotic manifestations (skin thickening and lung fibrosis). Based on the results of SLS II the best treatment option for skin involvement in SSc is mycophenolate mofetil (MMF). Methotrexate (MTX) is another option which is safe and of low cost but evidence supporting its use is weak. The standard of care for SSc-ILD nowadays is MMF. Patients not responding to MMF could be treated with rituximab (RTX) or cyclophosphamide (CYC) (tocilizumab [TCZ] could be an option as well but only for patients with increased inflammatory markers). Hematopoietic stem cell transplantation (HSCT) could be considered in patients with severe/life-threatening disease who have failed conventional treatment. The most promising therapeutic approach currently been evaluated in phase 3 trials is probably the combination of MMF plus pirfenidone.

Deregulated PSGL-1 Expression in B Cells and Dendritic Cells May Be Implicated in Human Systemic Sclerosis Development

Systemic sclerosis (SSc) is an autoimmune disorder with high morbidity and mortality, is difficult to diagnose early, and has no curative treatment. PSGL-1 is a leukocyte receptor whose deficiency in mice promotes an SSc-like disease. ADAM8, a metalloprotease that cleaves PSGL-1, is implicated in inflammatory processes. Our goal was to evaluate whether PSGL-1 and ADAM8 contribute to the pathogenesis of human SSc. We found that patients with SSc presented increased PSGL-1 expression on monocytes, dendritic cells, and T cells and decreased expression of PSGL-1 on B cells. PSGL-1 on monocytes from SSc patients failed to induce Syk phosphorylation or IL-10 production after interaction with P-selectin. Up to 60% of the IL-10-producing B cells expressed PSGL-1, pointing to a regulatory role for PSGL-1 in B cells, and PSGL-1⁺ B cells from SSc patients had decreased IL-10 production. ADAM8 expression was increased on antigen-presenting cells and T lymphocytes of SSc patients. Patients treated with calcium antagonists had lower levels of ADAM8 on APCs and T lymphocytes. Multivariate analysis indicated that the high percentage of ADAM8-expressing plasmacytoid dendritic cells discriminated patients from healthy donors. High PSGL-1 expression on dendritic cells was associated with the presence of interstitial lung disease.

Pathogenic roles of B lymphocytes in systemic sclerosis

Systemic sclerosis (SSc) is a collagen disease characterized by autoimmunity and excessive extracellular matrix deposition in the skin and visceral organs. Although the pathogenic relationship between systemic autoimmunity and the clinical manifestations of SSc remains unknown, SSc patients show a variety of abnormal immune activation including the production of disease-specific autoantibodies and cytokine production. Many recent studies have demonstrated that immune cells, including T cells, B cells, and macrophages, have a variety of immunological abnormalities in SSc. So far, several groups and our group reported that B cells play a critical role in systemic autoimmunity and disease expression through various functions, such as cytokine production, lymphoid organogenesis, and induction of other immune cell activation in addition to autoantibody production. Recent studies show that B cells from SSc patients demonstrate an up-regulated CD19 expression, a crucial regulator of B cell activation, which induces chronic hyper-reactivity of memory B cells and SSc-specific autoantibody production and also causes fibrosis of several organs. Furthermore, in SSc-model mice, such as tight-skin mice, bleomycin-induced SSc model mice, and DNA topoisomerase I and complete Freund's adjuvant-induced SSc model mice, have abnormal B cell activation which associates with skin and lung fibrosis. Indeed, B cell depletion therapy using anti-CD20 Ab, Rituximab, is considered to one potential beneficial treatment for patients with SSc. However, there is no direct evidence which can explain how B cells, especially autoantigen-reactive B cells, progress or regulate disease manifestations of SSc. Collectively, B cell abnormalities in SSc is most likely participating in fibrosis and tissue damage of SSc. If the relationship between SSc-specific tissue damage and B cell abnormalities is revealed, these findings lead to novel effective therapy for SSc.

The Superficial Dermis May Initiate Keloid Formation: Histological Analysis of the Keloid Dermis at Different Depths

Several studies have reported on certain aspects of the characteristics of different sites within a keloid lesion, but detailed studies on the keloid dermis at different depths within a keloid lesion are scarce. The aim of this study was to investigate the histology of the keloid dermis at different depths. This study included 19 keloid tissue samples that were collected from 19 patients and 19 normal skin samples, which were harvested from subjects without keloids or hypertrophic scar. Samples were studied by light microscopy using routine hematoxylin and eosin histochemical staining, and immunohistochemistry to detect CD20-positive B-lymphocytes and CD3-positive T-lymphocytes. Sirius Red histochemical staining was used to determine the type of collagen in keloid tissue and normal skin samples. The migratory properties of fibroblasts within the keloid dermis at different depths was compared, using an in vitro migration assay. The findings of this study showed that although the papillary and reticular dermis could be clearly distinguished in normal skin, three tissue layers were identified in the keloid dermis. The superficial dermis of keloid was characterized by active fibroblasts and lymphocytes; the middle dermis contained dense extracellular matrix (ECM) with large numbers fibroblasts, and the deep dermis was poorly cellular and characterized by hyalinized collagen bundles. In the keloid samples, from the superficial to the deep dermis, type I collagen increased and type III collagen decreased, and fibroblasts from the superficial dermis of the keloid were found to migrate more rapidly. In conclusion, the findings of this study showed that different depths within the keloid dermis displayed different biological features. The superficial dermis may initiate keloid formation, in which layer intralesional injection of pharmaceuticals and other treatments should be performed for keloid.

Dioscin Exerts Protective Effects Against Crystalline Silica-induced Pulmonary Fibrosis in Mice

Inhalation of crystalline silica particles leads to pulmonary fibrosis, eventually resulting in respiratory failure and death. There are few effective drugs that can delay the progression of this disease; thus, patients with silicosis are usually only offered supportive care. Dioscin, a steroidal saponin, exhibits many biological activities and health benefits including its protective effects against hepatic fibrosis. However, the effect of dioscin on silicosis is unknown.

Methods: We employed experimental mouse mode of silicosis. Different doses of dioscin were gavaged to the animals 1 day after crystalline silica instillation to see the effect of dioscin on crystalline silica induced pulmonary fibrosis. Also, we used RAW264.7 and NIH-3T3 cell lines to explore dioscin effects on macrophages and fibroblasts. Dioscin was also oral treatment but 10 days after crystalline silica instillation to see its effect on established pulmonary fibrosis.

Results: Dioscin treatment reduced pro-inflammation and pro-fibrotic cytokine secretion by modulating innate and adaptive immune responses. It also reduced the recruitment of fibrocytes, protected epithelial cells from crystalline silica injury, inhibited transforming growth factor beta/Smad3 signaling and fibroblast activation. Together, these effects delayed the progression of crystalline silica-induced pulmonary fibrosis. The mechanism by which dioscin treatment alleviated CS-induced inflammation appeared to be via the reduction of macrophage, B lymphocyte, and T lymphocte infiltration into lung. Dioscin inhibits macrophages and fibroblasts from secreting pro-inflammatory cytokines and may also function as a modulator of T helper cells responses, concurrent with attenuated phosphorylation of the apoptosis signal-regulating kinase 1-p38/c-Jun N-terminal kinase pathway. Also, dioscin could block the phosphorylation of Smad3 in fibroblast. Oral treatment of dioscin could also effectively postpone the progression of established silicosis.

Conclusion: Oral treatment dioscin delays crystalline silica-induced pulmonary fibrosis and exerts pulmonary protective effects in mice. Dioscin may be a novel and potent candidate for protection against crystalline silica-induced pulmonary fibrosis.

Transglutaminase 2 in human diseases

Transglutaminase 2 (TG2) is an inducible transamidating acyltransferase that catalyzes Ca(2+)-dependent protein modifications. In addition to being an enzyme, TG2 also serves as a G protein for several seven transmembrane receptors and acts as a co-receptor for integrin β1 and β3 integrins distinguishing it from other members of the transglutaminase family. TG2 is ubiquitously expressed in almost all cell types and all cell compartments, and is also present on the cell surface and gets secreted to the extracellular matrix via non-classical mechanisms. TG2 has been associated with various human diseases including inflammation, cancer, fibrosis, cardiovascular disease, neurodegenerative diseases, celiac disease in which it plays either a protective role, or contributes to the pathogenesis. Thus modulating the biological activities of TG2 in these diseases will have a therapeutic value.

B lymphocytes in systemic sclerosis: Abnormalities and therapeutic targets

Systemic sclerosis (SSc) is a connective tissue disease characterized by excessive extracellular matrix deposition in the skin and visceral organs with an autoimmune background. Although the pathogenic relationship between systemic autoimmunity and the clinical manifestations remains unknown, SSc patients have immunological abnormalities including the production of disease-specific autoantibodies. Recent studies have demonstrated that B cells play a crucial role in systemic autoimmunity and disease expression via various functions in addition to autoantibody production. Recent studies show that B cells from SSc patients demonstrate an upregulated CD19 signaling pathway, which is a crucial regulator of B-cell activation, that induces SSc-specific autoantibody production in SSc. In addition, B cells from SSc patients exhibit an overexpression of CD19. Consistently, in CD19 transgenic mice, CD19 overexpression induces SSc-specific autoantibody production. SSc patients have also intrinsic B-cell abnormalities characterized by chronic hyperreactivity of memory B cells, possibly due to CD19 overexpression. Similarly, B cells from a tight-skin mouse, a genetic model of SSc, show augmented CD19 signaling and chronic hyperreactivity. Furthermore, in bleomycin-induced SSc model mice, endogenous ligands for Toll-like receptors, induced by bleomycin treatment, stimulate B cells to produce various fibrogenic cytokines and autoantibodies. Remarkably, CD19 loss results in inhibition of B-cell hyperreactivity and elimination of autoantibody production, which is associated with improvement of fibrosis. Taken together, altered B-cell function may result in tissue fibrosis, as well as autoimmunity, in SSc. Although further studies and greater understanding are needed, B cells are potential therapeutic target in SSc.

A multicenter, open-label, comparative study of B-cell depletion therapy with Rituximab for systemic sclerosis-associated interstitial lung disease

OBJECTIVES

Rituximab (RTX) may favorably affect lung function and skin fibrosis in patients with systemic sclerosis (SSc). We aimed to assess long-term efficacy and safety of RTX in SSc compared to standard treatment.

METHODS

A total of 51 patients with SSc-associated interstitial lung disease were recruited and treated with RTX (n = 33) or conventional treatment (n = 18). Median follow-up was 4 years (range: 1-7). Conventional treatment consisted of azathioprine (n = 2), methotrexate (n = 6), and mycophenolate mofetil (n = 10).

RESULTS

Patients in the RTX group showed an increase in FVC at 2 years (mean ± SD of FVC: 80.60 ± 21.21 vs 86.90 ± 20.56 at baseline vs 2 years, respectively, p = 0.041 compared to baseline). In sharp contrast, patients in the control group had no change in FVC during the first 2 years of follow-up. At the 7 year time point the remaining patients in the RTX group (n = 5) had higher FVC compared to baseline (mean ± SD of FVC: 91.60 ± 14.81, p = 0.158 compared to baseline) in contrast to patients in the control group (n = 9) where FVC deteriorated (p < 0.01, compared to baseline). Direct comparison between the 2 groups showed a significant benefit for the RTX group in FVC (p = 0.013). Improvement of skin thickening was found in both the RTX and the standard treatment group; however, direct comparison between groups strongly favored RTX at all-time points. Adverse events were comparable between groups.

CONCLUSIONS

Our data indicate that RTX has a beneficial effect on lung function and skin fibrosis in patients with SSc. Randomized controlled studies are highly needed.

B cell depletion therapy upregulates Dkk-1 skin expression in patients with systemic sclerosis: association with enhanced resolution of skin fibrosis

BACKGROUND

Rituximab (RTX) may favorably affect skin and lung fibrosis in patients with systemic sclerosis (SSc); however, the underlying molecular mechanisms remain unknown. We aimed to explore the hypothesis that RTX may mediate its antifibrotic effects by regulating the expression of Dickkopf-1 (Dkk-1), an inhibitor of the Wnt pathway.

METHODS

Fourteen patients with SSc and five healthy subjects were recruited. Dkk-1 expression was immunohistochemically assessed in skin biopsies obtained from 11 patients with SSc (8 treated with RTX and 3 with standard treatment), whereas DKK1 gene expression was assessed in 3 patients prior to and following RTX administration.

RESULTS

In baseline biopsies obtained from all patients with SSc but not in healthy subjects, Dkk-1 was undetectable in skin fibroblasts. Following RTX treatment, four out of eight patients had obvious upregulation of Dkk-1 skin expression. Similarly, RTX treatment correlated with a significant 4.8-fold upregulation of DKK1 gene expression (p = 0.030). In contrast, TGFβ expression in the upper dermis was significantly attenuated following treatment. Moreover, this decreased expression of TGFβ in the skin was significantly more pronounced in the subgroup of patients with Dkk-1 upregulation. In this subgroup TGFβ was downregulated by 50.88 % in contrast to only 15.98 % in patients who did not have Dkk-1 upregulation (p = 0.022).

CONCLUSIONS

This is the first study demonstrating a link between B cell depletion and skin Dkk-1 upregulation in patients with SSc. RTX-mediated B cell depletion may mechanistically function via the recently established TGFβ-Dkk-1 axis in improving skin fibrosis.

Regulatory T Cells Contribute to the Inhibition of Radiation-Induced Acute Lung Inflammation via Bee Venom Phospholipase A₂ in Mice

Bee venom has long been used to treat various inflammatory diseases, such as rheumatoid arthritis and multiple sclerosis. Previously, we reported that bee venom phospholipase A₂ (bvPLA₂) has an anti-inflammatory effect through the induction of regulatory T cells. Radiotherapy is a common anti-cancer method, but often causes adverse effects, such as inflammation. This study was conducted to evaluate the protective effects of bvPLA₂ in radiation-induced acute lung inflammation. Mice were focally irradiated with 75 Gy of X-rays in the lung and administered bvPLA₂ six times after radiation. To evaluate the level of inflammation, the number of immune cells, mRNA level of inflammatory cytokine, and histological changes in the lung were measured. BvPLA₂ treatment reduced the accumulation of immune cells, such as macrophages, neutrophils, lymphocytes, and eosinophils. In addition, bvPLA₂ treatment decreased inflammasome-, chemokine-, cytokine- and fibrosis-related genes' mRNA expression. The histological results also demonstrated the attenuating effect of bvPLA₂ on radiation-induced lung inflammation. Furthermore, regulatory T cell depletion abolished the therapeutic effects of bvPLA₂ in radiation-induced pneumonitis, implicating the anti-inflammatory effects of bvPLA₂ are dependent upon regulatory T cells. These results support the therapeutic potential of bvPLA₂ in radiation pneumonitis and fibrosis treatments.

MicroRNAs as potential targets for progressive pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive and devastating disorder. It is characterized by alveolar epithelial cell injury and activation, infiltration of inflammatory cells, initiation of epithelial mesenchymal transition (EMT), aberrant proliferation and activation of fibroblasts, exaggerated deposition of extracellular matrix (ECM) proteins, and finally leading to the destruction of lung parenchyma. MicroRNAs (miRNAs) are endogenous small non-coding RNA molecules that post-transcriptionally regulate gene expression in diverse biological and pathological processes, including cell proliferation, differentiation, apoptosis and metastasis. As a result, miRNAs have emerged as a major area of biomedical research with relevance to pulmonary fibrosis. In this context, the present review discusses specific patterns of dysregulated miRNAs in patients with IPF. Further, we discuss the current understanding of miRNAs involvement in regulating lung inflammation, TGF-β1-mediated EMT and fibroblast differentiation processes, ECM genes expression, and in the progression of lung fibrosis. The possible future directions that might lead to novel therapeutic strategies for the treatment of pulmonary fibrosis are also reviewed.

The inflammasome accelerates radiation-induced lung inflammation and fibrosis in mice

Although lung inflammation and fibrosis are well-documented dose-limiting side effects of lung irradiation, the mechanisms underlying these pathologies are unknown. An improved mechanistic understanding of radiation-induced pneumonitis is a prerequisite for the development of more effective radiotherapy; this was the rationale for the current study. Mouse lungs were focally irradiated with 75 Gy. The numbers of neutrophils, lymphocytes, macrophages, and total cells in the bronchoalveolar lavage fluid were counted, and pro-inflammatory cytokine levels were measured. Histological analysis and immunohistochemical staining for Tgf-β1 and Cd68 (a macrophage-specific protein) was also performed. After irradiation, mice developed pneumonitis, and exhibited higher numbers of neutrophils, lymphocytes, eosinophils, macrophages, and total cells compared to controls. In addition, inflammasome (Nlrp3, and caspase 1, Il1a, and Il1β), adhesion molecule (Vcam1), and cytokine (Il6) genes were significantly upregulated in the IR group. Cd68 and Tgfb1 proteins were significantly increased after irradiation. Upregulation of Cd68 and Tgfb1 correlates with the onset of radiation-induced pneumonitis and fibrosis. In addition, radiation-induced pneumonitis and fibrosis are accompanied by upregulation of phenotypic markers of inflammasome activity. Our findings have implications for the onset and exacerbation of damage in normal lung tissue.

Cellular interactions in the pathogenesis of interstitial lung diseases

Interstitial lung disease (ILD) encompasses a large and diverse group of pathological conditions that share similar clinical, radiological and pathological manifestations, despite potentially having quite different aetiologies and comorbidities. Idiopathic pulmonary fibrosis (IPF) represents probably the most aggressive form of ILD and systemic sclerosis is a multiorgan fibrotic disease frequently associated with ILD. Although the aetiology of these disorders remains unknown, in this review we analyse the pathogenic mechanisms by cell of interest (fibroblast, fibrocyte, myofibroblast, endothelial and alveolar epithelial cells and immune competent cells). New insights into the complex cellular contributions and interactions will be provided, comparing the role of cell subsets in the pathogenesis of IPF and systemic sclerosis.

Distinct cell populations contribute to the complex pathogenesis of IPF and systemic sclerosis-associated ILDhttp://ow.ly/AjFaz

Abnormal B lymphocyte activation and function in systemic sclerosis

Systemic sclerosis (SSc) is characterized by tissue fibrosis and autoimmunity. Although the pathogenic relationship between autoimmunity and clinical manifestations of SSc remains unknown, SSc patients display abnormal immune responses including the production of disease-specific autoantibodies. Previous studies have demonstrated that B cells play a critical role in systemic autoimmunity and disease expression through various functions such as induction of the activation of other immune cells in addition to autoantibody production. CD19 is a crucial regulator of B cell activation. Recent studies demonstrated that B cells from SSc patients showed an up-regulated CD19 signaling pathway that induced SSc-specific autoantibody production in SSc mouse models. CD19 transgenic mice lost tolerance for autoantigen and generated autoantibodies spontaneously. B cells from SSc patients exhibited an overexpression of CD19 that induced SSc-specific autoantibody production in transgenic mice. Moreover, SSc patients displayed intrinsic B cell abnormalities characterized by chronic hyper-reactivity of memory B cells, which was possibly due to CD19 overexpression. Similarly, B cells from a tight-skin mouse, a genetic model of SSc, showed augmented CD19 signaling. In bleomycin-induced SSc mouse models, endogenous ligands for toll-like receptor 4 induced by bleomycin stimulated B cells to produce various fibrogenic cytokines and autoantibodies. Remarkably, the loss of CD19 resulted in the inhibition of B cell hyper-reactivity and autoantibody production, which are associated with improvements in fibrosis and a parallel decrease in fibrogenic cytokine production by B cells. Taken together, the findings suggest that altered B cell function may result in tissue fibrosis as well as autoimmunity in SSc.

Dermal dendritic cell population and blood vessels are diminished in the skin of systemic sclerosis patients: relationship with fibrosis degree and disease duration

Recent studies have suggested that the number of dermal dendritic cells is altered in the skin of patients with scleroderma and that these cells may have an important role in the pathogenesis of this disease. There is also a belief that insufficient blood flow to the affected organs may also be responsible for the disease. Our aim was to quantify CD34+ cells, factor XIIIa cells, and blood vessels in the skin of patients with systemic sclerosis and to correlate these data with fibrosis degree and duration of disease. Paraffin-embedded skin sections from patients with systemic sclerosis and from healthy subjects were immunolabelled with antibodies against CD34+ and factor XIIIa. Cells and blood vessels were quantified in the papillary and reticular dermis. Both, the number of CD34+ cells and factor XIIIa cells in the skin of patients with systemic sclerosis were reduced. The reduction of these cell types preceded the appearance of intense fibrosis, suggesting that fibrosis is not responsible of this phenomenon. Blood vessel volume and surface density were also reduced in the skin of systemic sclerosis patients. This reduction was also noted early in the evolution of the disease. Our results suggest that CD34+ cells and factor XIIIa cells may contribute to normal regulation of extracellular matrix assembly. We confirmed the observation that capillary density is diminished in scleroderma skin.

Serum B-cell activating factor assessment in a population of Egyptian patients with systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a rare systemic connective tissue disease characterized by abnormal fibroblast proliferation and micro-vascular inflammatory changes.

AIM

To assess serum B-cell activating factor (BAFF) levels in patients with systemic sclerosis and to correlate this with disease features and disease severity.

METHODS

This is a case-control study in which patients with the established diagnosis of SSc were recruited. The diagnosis of SSc was established according to the American Rheumatology Association 1980 criteria for the classification of scleroderma. Patients' assessment included evaluation of skin involvement using the Modified Rodnan score and disease severity using the Medsger score. Twenty-five healthy matching controls were included. The sandwich enzyme-linked immunosorbent assay technique was used for direct assessment of serum BAFF in patients and controls.

RESULTS

The study included 60 patients (54 female and 6 male), with a mean age of 38.18 ± 12.06 years, with mean disease duration of 7.85 ± 4.075 years. Serum BAFF in patients ranged 98.2-5015 pg/mL with mean BAFF 1100 ± 835.4 pg/mL. In controls serum BAFF levels ranged 188.5-2314 pg/mL with mean BAFF 546.1 ± 471.1 pg/mL, showing a statistically significant elevation of serum BAFF levels in SSc patients (P = 0.0001) with insignificant correlation to skin disease or total Medsgar Score of the study population (P > 0.05). Serum BAFF levels showed significant correlation with episodes of pseudo-obstruction and methotrexate (MTX) use in the patients studied (P < 0.05).

CONCLUSION

Serum BAFF levels were significantly elevated in patients with SSc irrespective of disease subtype, disease duration or age of patients. This elevation in serum BAFF significantly related to gastrointestinal track involvement and MTX therapy.

Swimming exercise prevents fibrogenesis in chronic kidney disease by inhibiting the myofibroblast transdifferentiation

Background

The renal function of chronic kidney disease (CKD) patients may be improved by a number of rehabilitative mechanisms. Swimming exercise training was supposed to be beneficial to its recovery.

Methodology/Principal Findings

Doxorubicin-induced CKD (DRCKD) rat model was performed. Swimming training was programmed three days per week, 30 or 60 min per day for a total period of 11 weeks. Serum biochemical and pathological parameters were examined. In DRCKD, hyperlipidemia was observed. Active mesangial cell activation was evidenced by overexpression of PDGFR, P-PDGFR, MMP-2, MMP-9, α-SMA, and CD34 with a huge amount collagen deposition. Apparent myofibroblast transdifferentiation implicating fibrogenesis in the glomerular mesangium, glomerulonephritis and glomeruloscelorosis was observed with highly elevated proteinuria and urinary BUN excretion. The 60-min swimming exercise but not the 30 min equivalent rescued most of the symptoms. To quantify the effectiveness of exercise training, a physical parameter, i.e. “the strenuosity coefficient” or “the myokine releasing coefficient”, was estimated to be 7.154×10⁻³ pg/mL-J.

Conclusions

The 60-min swimming exercise may ameliorate DRCKD by inhibiting the transdifferentiation of myofibroblasts in the glomerular mesangium. Moreover, rehabilitative exercise training to rescue CKD is a personalized remedy. Benefits depend on the duration and strength of exercise, and more importantly, on the individual physiological condition.

Role of MicroRNAs in Fibrosis

Fibrosis is the leading cause of organ dysfunction in diseases such as systemic sclerosis, liver cirrhosis, cardiac fibrosis, progressive kidney disease, and idiopathic pulmonary fibrosis. The hallmark of fibrosis is tissue remodeling with excess deposition of extracellular matrix components, predominantly collagens. Different cell types, cytokines, growth factors, and enzymes interact in complex pathogenic networks with myofibroblasts playing a pivotal role. MicroRNAs are small non-coding RNAs acting as negative regulators of gene expression at the post-transcriptional level. MicroRNAs have been associated with many basic cellular processes as well as with a wide spectrum of diseases, most notably cancer. This review provides a comprehensive overview of microRNAs regulating profibrotic pathways and extracellular matrix synthesis. The potential of miRNA for targeted therapeutic approaches in fibrotic disorders is also discussed.

The pathogenesis of systemic sclerosis revisited

Although infectiological stimuli, environmental factors and genotypic features are known to contribute to the initiation and perpetuation of systemic sclerosis (SSc), its etiology still remains to be enigmatic, and less elusive insights are to be achieved by ongoing and future investigations. Being characterized, however, as chronic autoimmune disease with excessive collagen accumulation in skin, synovia and visceral organs such as lung, heart, and digestive tract along with obliterating angiopathy, the pathophysiology of SSc can be summarized as being based on imbalances of the cellular and humoral immune system, vascular dysfunction and activation of resident connective tissue cells. A complex interplay between these major components manages to establish and maintain the inability of the vasculature to adequately react to the need for dilatation, constriction and growth of new vessels, to cause the increased deposition of extracellular matrix constituents as well as to facilitate immunological disarrangement. Despite parallels to the chicken and egg causality dilemma, all of these account for what later clinicians observe in patients suffering from Raynaud's phenomenon, digital ulcers, sclerodactyly, rigidity of the face, microstomia, sicca syndrome, dyspnea, dry cough, pulmonary hypertension, palpitations, syncopes, renal insufficiency, dysphagia, gastroesophageal reflux, dyspepsia, generalized arthralgias, but also dyspareunia, or erectile dysfunction.

IL-6-induced pathophysiology during pre-eclampsia: potential therapeutic role for magnesium sulfate?

Pre-eclampsia is defined as new onset hypertension with proteinuria during pregnancy. Pre-eclampsia is also characterized by endothelial cell activation and dysfunction and intrauterine growth restriction. Preeclamptic women display a chronic inflammatory response characterized by elevated inflammatory cytokines, circulating monocytes, neutrophils, and T and B lymphocytes secreting autoantibodies that activate the angiotensin II type I receptor (AT1-AA). Although the pathophysiology of pre-eclampsia is becoming more defined, the genesis of the disease is still largely unknown. Furthermore, the only treatment for extreme forms of the disease is bed rest and administration of magnesium sulfate to sustain the pregnancy a few days prior to early delivery of the fetus, which can lead to devastating neurological and physical effects for the newborn. Administration of magnesium sulfate is routinely given without adverse effects. The focus of this review is to discuss the cascade of events leading to cytokines, specifically interleukin-6 (IL-6), in stimulating vasoactive substances such as AT1-AA (Figure 1) and to examine the mechanism whereby administration of magnesium sulfate can be beneficial during pre-eclampsia. One area is to decrease vascular resistance index parameters determined by Doppler velocimetry. Another potential area of benefit with magnesium sulfate administration may be to decrease inflammatory responses or decrease cardiovascular mechanisms stimulated by overexpression of inflammatory cytokines in response to placental ischemia or animal models of elevated IL-6 during pregnancy. Further studies identifying IL-6-driven mechanisms playing a role in the development of hypertension during pregnancy and how administration of magnesium sulfate can suppress them are critical to improve decisions affecting patient care in women with pre-eclampsia. The results of these types of studies will be advantageous to further our knowledge of the pathophysiological ramifications associated with pre-eclampsia and to further therapeutic development for this disease.

Remodeling and homeostasis of the extracellular matrix: implications for fibrotic diseases and cancer

Dynamic remodeling of the extracellular matrix (ECM) is essential for development, wound healing and normal organ homeostasis. Life-threatening pathological conditions arise when ECM remodeling becomes excessive or uncontrolled. In this Perspective, we focus on how ECM remodeling contributes to fibrotic diseases and cancer, which both present challenging obstacles with respect to clinical treatment, to illustrate the importance and complexity of cell-ECM interactions in the pathogenesis of these conditions. Fibrotic diseases, which include pulmonary fibrosis, systemic sclerosis, liver cirrhosis and cardiovascular disease, account for over 45% of deaths in the developed world. ECM remodeling is also crucial for tumor malignancy and metastatic progression, which ultimately cause over 90% of deaths from cancer. Here, we discuss current methodologies and models for understanding and quantifying the impact of environmental cues provided by the ECM on disease progression, and how improving our understanding of ECM remodeling in these pathological conditions is crucial for uncovering novel therapeutic targets and treatment strategies. This can only be achieved through the use of appropriate in vitro and in vivo models to mimic disease, and with technologies that enable accurate monitoring, imaging and quantification of the ECM.

Hypertension in response to placental ischemia during pregnancy: role of B lymphocytes

Preeclampsia is associated with innate inflammatory response resulting in elevated tumor necrosis factor-α, agonistic autoantibodies to the angiotensin II type I receptor, and activation of endothelin 1 (ET-1). This study was designed to determine the role of B-cell depletion, resulting in agonistic autoantibodies to the angiotensin II type I receptor suppression to mediate hypertension via activation of ET-1 in the placental ischemic reduced uterine perfusion pressure (RUPP) rat model of preeclampsia. To achieve this goal we examined the effect of RUPP on mean arterial pressure and ET-1 in the presence and absence of chronically infused rituximab (R; 250 mg/kg), a B-lymphocyte-suppressive agent used clinically to treat autoimmune diseases. Mean arterial pressure was 103±1 mm Hg in normal pregnant (NP) rats; 103±3 mm Hg in NP+R versus 133±2 mm Hg in RUPP rats, and 118±2 mm Hg in RUPP+R rats (P<0.001 vs RUPP controls). B lymphocytes decreased from 6.0±0.5% gated cells in RUPP to 3.7±0.8% gated cells in RUPP+R rats. Importantly, agonistic autoantibodies to the angiotensin II type I receptor decreased from 18±1 bpm in RUPP rats to 10±1 bpm in RUPP+R rats. ET-1 decreased 1.5-fold in kidneys and 4-fold in the placenta (P<0.01) of RUPP+R versus RUPP rats. Media ET-1 excretion from endothelial cells exposed to serum from NP, RUPP, NP+R, or RUPP+R rats was determined. ET-1 from endothelial cells treated with NP serum was 53+13 pg/mg and increased to 75+10 pg/mg with RUPP serum. In contrast, ET-1 secretion decreased in response to B-cell-depleted RUPP serum to 50±8 pg/mg and was unchanged in response to NP+R sera (46±12 pg/mg). These data demonstrate the important roles that B-lymphocyte activation and agonistic autoantibodies to the angiotensin II type I receptors play in the pathophysiology of hypertension in response to placental ischemia.

Gadolinium-promoted precipitation of calcium phosphate is associated with profibrotic activation of RAW 264.7 macrophages

Gadolinium-based contrast agents are now being linked to nephrogenic systemic fibrosis (NSF). The exact mechanism by which gadolinium species act in the pathogenesis of NSF is not fully understood. In this study, we evaluated the effect of gadolinium chloride (GdCl(3)) on the precipitation of calcium phosphate, and examined the role of the gadolinium-containing precipitates in the profibrotic activation of macrophages. In a free-drift system, the induction time was markedly reduced with increasing concentration of GdCl(3), accompanied by alterations of morphology and composition of the precipitates. In complete cell culture medium, the addition of GdCl(3) resulted in formation of particles around 200-300 nm. In an in vitro cellular model with RAW 264.7 macrophages, GdCl(3) increased the production of TGF-beta1 and IL-6 via the activation of PKC and ERK signaling pathway. Our findings demonstrate that GdCl(3) promotes calcium phosphate precipitation and induces profibrotic activation of macrophages.

Association of the C8orf13-BLK region with systemic sclerosis in North-American and European populations

OBJECTIVE

Genetic studies in the systemic sclerosis (SSc), an autoimmune disease that clinically manifests with dermal and internal organ fibrosis and small vessel vasculopathy, have identified multiple susceptibility genes including HLA-class II, PTPN22, IRF5, and STAT4 which have also been associated with other autoimmune diseases, such as systemic lupus erythematosus (SLE). These data suggest that there are common autoimmune disease susceptibility genes. The current report sought to determine if polymorphisms in the C8orf13-BLK region (chromosome 8p23.1-B lymphoid tyrosine kinase), which is associated with SLE, are associated also with SSc.

METHODS

Two variants in the C8orf13-BLK region (rs13277113 & rs2736340) were tested for association with 1050 SSc cases and 694 controls of North Americans of European descent and replicated in a second series 589 SSc cases and 722 controls from Spain.

RESULTS

The "T" allele at rs2736340 variant was associated with SSc in both the U.S. and Spanish case-control series (P = 6.8 x 10(-5), OR 1.27, 95% CI 1.1-1.4). The "A" allele at rs13277113 variant was associated with SSc in the U.S. series only (P = 3.6 x 10(-4), OR 1.32, 95% CI 1.1-1.6) and was significant in the combined analyses of the two series (P = 2.0 x 10(-3); OR 1.20, 95% CI 1.1-1.3). Both variants demonstrated an association with the anti-centromere antibody (P = 2.2 x 10(-6) and P = 5.5 x 10(-4), respectively) and limited SSc (P = 3.3 x 10(-5) and P = 2.9 x 10(-3), respectively) in the combined analysis. Peripheral blood gene expression profiles suggest that B-cell receptor and NFkappaB signaling are dysregulated based on the risk haplotype of these variants.

CONCLUSION

We identify and replicate the association of the C8orf13-BLK region as a novel susceptibility factor for SSc, placing it in the category of common autoimmune disease susceptibility genes.

Ocular manifestations of scleroderma

Systemic sclerosis is a chronic multi-system disorder predominantly affecting the skin, musculoskeletal, gastrointestinal, pulmonary, and renal systems. Although the exact etiology is unknown, recent evidence suggests that immune activation play a pivotal role in the pathogenesis. Ocular involvement in systemic sclerosis has been documented; however, due to the rare nature of the disease, most papers have been single case reports or small case series. This review paper aims to consolidate the findings of previous papers with a view to providing a comprehensive review of the ocular manifestations of systemic sclerosis.

Interleukin (IL)-6 modulates transforming growth factor-beta expression in skin and dermal fibroblasts from IL-6-deficient mice

BACKGROUND

Interleukin (IL-6) and transforming growth factor (TGF)-beta have been shown to play a role in skin development and maintenance.

OBJECTIVES

A link between these two cytokines has yet to be identified and therefore in this study we investigated the modulation of TGF-beta1 and TGF-beta type 2 receptor (TGF-betaR2) by IL-6 in skin.

METHODS

An IL-6 knockout (IL-6KO) fibroblast-populated lattice model and intradermal injections of IL-6 into unwounded IL-6KO mice were used to investigate the direct effects of IL-6 treatment on TGF-beta and TGF-betaR2 expression and to determine the signalling mechanism. In addition, IL-6KO and C57BL/6 control mice were wounded by a 4-mm punch biopsy to monitor expression of TGF-beta1 and TGF-betaR2 within a wound over time. The expression of TGF-beta1 and TGF-betaR2 was assessed by real-time quantitative polymerase chain reaction, enzyme-linked immunosorbent assay and immunohistology.

RESULTS

Recombinant IL-6 treatment of IL-6KO lattices and intradermal injections of IL-6 showed a significant induction of TGF-beta1 mRNA and protein, with TGF-beta1 expression localized in the dermis, while TGF-betaR2 expression was primarily in the epidermis in IL-6KO mice. During healing, the expression of TGF-beta1 and TGF-betaR2 mRNA was significantly greater in unwounded and 7-day-old wounds from wild-type mice; however, protein expression did not differ. Treatment with signal transduction inhibitors indicated that IL-6 modulates TGF-beta through a mitogen-activated protein kinase/extracellular signal-regulated kinase (Mapk/Erk)-dependent mechanism.

CONCLUSION

These studies indicate that IL-6 has the ability to modulate the expression of TGF-beta and TGF-betaR2 to varying degrees in the skin, which may provide a possible mechanism for defining the role of IL-6 in skin maintenance and a new association of IL-6 with TGF-beta in pathologies associated with fibrosis.

Apolipoprotein A-I and its role in lymphocyte cholesterol homeostasis and autoimmunity

OBJECTIVE

The purpose of this study was to determine the effects of an atherogenic diet on immune function in LDLr(-/-), ApoA-I(-/-) mice.

METHODS AND RESULTS

When LDLr(-/-), ApoA-I(-/-) (DKO), and LDLr(-/-) (SKO) mice were fed an atherogenic diet, DKO had larger peripheral lymph nodes (LNs) and spleens compared to SKO mice. LNs were enriched in cholesterol and contain expanded populations of T, B, dendritic cells, and macrophages. Expansion of all classes of LN cells was accompanied by a approximately 1.5-fold increase in T cell proliferation and activation. Plasma antibodies to dsDNA, beta2-glycoprotein I, and oxidized LDL were increased in DKO, similar to levels in diet-fed Fas(lpr/lpr) mice, suggesting the development of an autoimmune phenotype. Both LN enlargement and cellular cholesterol expansion were "prevented" when diet-fed DKO mice were treated with helper dependent adenovirus expressing apoA-I. Independent of the amount of dietary cholesterol, DKO mice consistently showed lower plasma cholesterol than SKO mice, yet greater aortic cholesterol deposition and inflammation.

CONCLUSIONS

ApoA-I prevented cholesterol-associated lymphocyte activation and proliferation in peripheral LN of diet-fed DKO mice. A approximately 1.5-fold increase in T cell activation and proliferation was associated with a approximately 3-fold increase in concentrations of circulating autoantibodies and approximately 2-fold increase in the severity of atherosclerosis suggesting a common link between plasma apoA-I, inflammation, and atherosclerosis.

Cyclophosphamide treatment improves microvessel damage in systemic sclerosis

The objective of this study is to evaluate nailfold videocapillaroscopy changes in scleroderma patients treated regularly on cyclic basis with iloprost and to find associations with clinical, serologic, and pharmacological variables. Forty-nine patients affected by systemic sclerosis (44 women and five men, mean age 52.4 years, mean disease duration 8.0 years, 31 patients with limited cutaneous subset and 18 with diffuse cutaneous form of the disease) underwent two nailfold videocapillaroscopies at a distance of 3 years from each other; the examinations were performed by an operator blinded to clinical features and to drug treatment. Six patients showed an amelioration of nailfold videocapillaroscopic abnormalities who changed from active to early pattern; five of these cases (83.3%) had been given cyclophosphamide therapy and the remaining case methotrexate plus azathioprine. Cyclophosphamide administration was significantly associated with amelioration of nailfold videocapillaroscopic pattern (p<0.001). None of the patients who received cyclophosphamide demonstrated worsening of the microvascular lesions; the progression of nailfold videocapillaroscopic pattern was inversely correlated to cyclophosphamide treatment (p=0.02). In our study, cyclophosphamide treatment demonstrated to be effective for scleroderma microvascular damage as directly observed by nailfold videocapillaroscopy.

Pathogenesis and therapeutic approaches for improved topical treatment in localized scleroderma and systemic sclerosis

SSc is a chronic progressive disorder of unknown aetiology characterized by excess synthesis and deposition of collagen and other extracellular matrix components in a variety of tissues and organs. Localized scleroderma (LS) differs from SSc in that with LS only skin and occasionally subcutaneous tissues are involved. Although rarely life threatening, LS can be disfiguring and disabling and, consequently, can adversely affect quality of life. There is no known effective treatment for LS, and various options, including, as examples, corticosteroids and other immunomodulatory agents, ultraviolet radiation and vitamin D analogues, are of unproven efficacy. Clinical trials evaluating combination therapy such as corticosteroids with MTX or UVA1 exposure with psoralens have not been established as consistently effective. New immunomodulators such as tacrolimus and thalidomide are also being evaluated. A better understanding of the molecular and cellular mechanisms of LS has led to evaluation of new treatments that modulate profibrotic cytokines such as TGF-beta and IL-4, regulate assembly and deposition of extracellular matrix components, and restore Th1/Th2 immune balance by administering IL-12 or IFN-gamma. IFN-gamma acts by directly inhibiting collagen synthesis and by restoring immune balance. In this review, we evaluate current and future treatment options for LS and cutaneous involvement in SSc. Recent advances in therapy focus mainly on anti-fibrotic agents. Delivery of these drugs into the skin as the target tissue might be a key factor in developing more effective and safer therapy.

Deletion of bradykinin B1 receptor reduces renal fibrosis

The Kallikrein-kinin system works through activation of two receptors. One constitutive, named B2 receptor (B2R) and another inducible, denominated B1 receptor (B1R). In renal fibrosis, B2R receptor activation appears to be protective, however B1R participation is unveiled. The aim of this study was to analyze how the deletion of the B1R would modify tissue responses after unilateral ureteral obstruction (UUO). For that, B1R knockout (B1KO) and wild-type mice (B1B2WT) were subjected to UUO and sacrificed at days 1, 5 and 14. Renal dysfunction was assayed by urine proteinuria/creatinine ratio and percentage of tubulointerstitial fibrosis. Kidneys were harvested at day 5 to analyze anti and pro-inflammatory molecules expression by real-time PCR. We demonstrated that at all time points, B1KO mice presented lower proteinuria/creatinine ratio from bladder urine. B1KO protection was reinforced by its lower tubular interstitial fibrosis percentage at day 14 (B1B2WT: 12.16+/-1.53% vs. B1KO: 6.73+/-1.07%, p<0.02). UUO was able to induce B1R expression and its highest transcription was achieved at day 5. At this day, B1KO had significant lower expression of pro-inflammatory molecules such as TGF-beta, MCP-1, OPN and IL-6 and higher anti-inflammatory components, as IL-10 and HO-1. Herein, we observed that B1R deletion may be an important component in renal fibrosis prevention.

Effects of T lymphocytes, interleukin-1, and interleukin-6 on renal fibrosis in canine end-stage renal disease

Canine end-stage renal disease (ESRD) is defined as the almost complete failure of renal function or irreversible destruction and is characterized by extensive glomerular sclerosis, tubular atrophy, interstitial inflammation, and fibrosis. Renal fibrosis is a common pathway leading to kidney failure. Infiltrating immunocytes in the end-stage kidney and several related factors are involved in renal fibrogenesis. A total of 18 renal tissue samples were obtained from canine patients with ESRD using biopsy and necropsy procedures. The extent of renal fibrosis was histopathologically examined by Masson trichrome staining. T-cell and B-cell localization and macrophage lineages were determined by immunohistochemical staining. Additionally, interleukin-1 (IL-1), IL-2, and IL-6 levels in the canine ESRD kidney were immunohistochemically evaluated and compared with expression patterns in the normal kidney. Significant fibrosis and infiltrating immunocytes consistent with lymphocytes were observed. Although the B-cell count was increased in the end-stage kidney, immunostaining patterns disclosed a marked increase in the number of CD3(+) cells. Furthermore, the remarkable increase in IL-1 and IL-6 levels suggests that T cells in the kidneys of dogs with ESRD spontaneously express these cytokines. In this study, the correlation between the degree of renal fibrosis and cytokines in canine ESRD was examined. The present study shows that T lymphocytes and IL-6 play important roles in renal fibrosis.

The therapeutic potential of bone marrow-derived mesenchymal stem cells on hepatic cirrhosis

Hepatic cirrhosis is the end-stage of chronic liver diseases. The majority of patients with hepatic cirrhosis die from life-threatening complications occurring at their earlier ages. Liver transplantation has been the most effective treatment for these patients. Since liver transplantation is critically limited by the shortage of available donor livers, searching for an effective alternative therapy has attracted great interest in preclinical studies. The transplantation of autologous bone marrow-derived mesenchymal stem cells holds great potential for treating hepatic cirrhosis. Mesenchymal stem cells can differentiate to hepatocytes, stimulate the regeneration of endogenous parenchymal cells, and enhance fibrous matrix degradation. Experimental and clinical studies have shown promising beneficial effects. This review is intended to translate the bench study results to the patients' bedside. The potential interventions of mesenchymal stem cells on cirrhosis are illustrated in terms of the cellular and molecular mechanisms of hepatic fibrogenesis.

Association of IL-10 receptor 2 (IL10RB) SNP with systemic sclerosis

Interleukin-10 (IL-10) signaling has been suggested to play a role in systemic sclerosis (SSc). IL10RB codes for IL-10 receptor 2 (IL-10R2), a component shared in receptor complexes for IL-10, IL-22, IL-26 and interferon (IFN)-lambda. In this study, we examined association of IL10RB polymorphism with susceptibility to SSc. Genotype A/A at rs2834167 (47K/K) was significantly increased in diffuse cutaneous SSc (dcSSc) (41.3% in dcSSc, 20.9% in controls, P=0.0018, odds ratio=2.67). A SNP in the 5' flanking region of IL10RB, rs999788, also showed association with dcSSc; however, this association was shown to be secondarily caused by linkage disequilibrium with rs2834167. Significant association was not observed in limited cutaneous SSc (lcSSc). Presence of anti-topoisomerase I antibody was also associated with rs2834167A/A genotype (P=0.0019). Serum IL-10 level was significantly associated with the number of rs2834167A allele (P=0.007). These findings suggested that signaling through IL-10R2 may play a causative role in dcSSc.

Pharmacological blockade of A2A receptors prevents dermal fibrosis in a model of elevated tissue adenosine

Adenosine is a potent modulator of inflammation and tissue repair. We have recently reported that activation of adenosine A(2A) receptors promotes collagen synthesis by human dermal fibroblasts and that blockade or deletion of this receptor in mice protects against bleomycin-induced dermal fibrosis, a murine model of scleroderma. Adenosine deaminase (ADA) is the principal catabolic enzyme for adenosine in vivo, and its deficiency leads to the spontaneous development of pulmonary fibrosis in mice. The aim of this study was to characterize further the contributions of endogenous adenosine and adenosine A(2A) receptors to skin fibrosis. Taking advantage of genetically modified ADA-deficient mice, we herein report a direct fibrogenic effect of adenosine on the skin, in which increased collagen deposition is accompanied by increased levels of key mediators of fibrosis, including transforming growth factor beta1, connective tissue growth factor, and interleukin-13. Pharmacological treatment of ADA-deficient mice with the A(2A) receptor antagonist ZM-241385 prevented the development of dermal fibrosis in this model of elevated tissue adenosine, by reducing dermal collagen content and expression of profibrotic cytokines and growth factors. These data confirm a fibrogenic role for adenosine in the skin and reveal A(2A) receptor antagonists as novel therapeutic agents for the modulation of dermal fibrotic disorders.

Oral tolerance attenuates changes in in vitro lung tissue mechanics and extracellular matrix remodeling induced by chronic allergic inflammation in guinea pigs

Recent studies emphasize the presence of alveolar tissue inflammation in asthma. Immunotherapy has been considered a possible therapeutic strategy for asthma, and its effect on lung tissue had not been previously investigated. Measurements of lung tissue resistance and elastance were obtained before and after both ovalbumin and acetylcholine challenges. Using morphometry, we assessed eosinophil and smooth muscle cell density, as well as collagen and elastic fiber content, in lung tissue from guinea pigs with chronic pulmonary allergic inflammation. Animals received seven inhalations of ovalbumin (1-5 mg/ml; OVA group) or saline (SAL group) during 4 wk. Oral tolerance (OT) was induced by offering ad libitum ovalbumin 2% in sterile drinking water starting with the 1st inhalation (OT1 group) or after the 4th (OT2 group). The ovalbumin-exposed animals presented an increase in baseline and in postchallenge resistance and elastance related to baseline, eosinophil density, and collagen and elastic fiber content in lung tissue compared with controls. Baseline and post-ovalbumin and acetylcholine elastance and resistance, eosinophil density, and collagen and elastic fiber content were attenuated in OT1 and OT2 groups compared with the OVA group. Our results show that inducing oral tolerance attenuates lung tissue mechanics, as well as eosinophilic inflammation and extracellular matrix remodeling induced by chronic inflammation.