Fibrosis In Multiple Organs Research Articles

Targeting CD38-Dependent NAD+ Metabolism to Mitigate Multiple Organ Fibrosis

Synchronous fibrosis in multiple organs is the defining hallmark of systemic sclerosis (SSc), but underlying mechanisms remain poorly understood. Organismal decline in nicotinamide adenine dinucleotide (NAD+), the sole substrate for enzymes critical for cellular metabolism, is implicated in age-related pathologies, and is due to NAD+ consumption catalyzed by CD38. We now show that CD38 is upregulated in SSc skin biopsies, and its levels associate with molecular fibrosis signatures as well as clinical skin fibrosis scores, while key NAD+ -synthesizing enzyme levels are unaltered. Boosting NAD+ via CD38 targeting or by NAD+ precursor supplementation protected older mice from skin and lung fibrosis. Mechanistically, CD38 reduced NAD+ levels and sirtuin activity to augment fibrotic responses, while inhibition of CD38 had the opposite effect. Thus we identify upregulation of CD38 and resulting disrupted NAD+ homeostasis as a fundamental pathogenic mechanism driving fibrosis in SSc, suggesting that CD38 might represent a target for therapy.

Extracellular SPARC cooperates with TGF-β signalling to induce pro-fibrotic activation of systemic sclerosis patient dermal fibroblasts.

ObjectivesSSc is an autoimmune disease characterized by inflammation, vascular injury and excessive fibrosis in multiple organs. Secreted protein acidic and rich in cysteine (SPARC) is a matricellular glycoprotein that regulates processes involved in SSc pathology, such as inflammation and fibrosis. In vivo and in vitro studies have implicated SPARC in SSc, but it is unclear if the pro-fibrotic effects of SPARC on fibroblasts are a result of intracellular signalling or fibroblast interactions with extracellular SPARC hampering further development of SPARC as a potential therapeutic target. This study aimed to analyse the potential role of exogenous SPARC as a regulator of fibrosis in SSc.MethodsDermal fibroblasts from both healthy controls and SSc patients were stimulated with SPARC alone or in combination with TGF-β1, in the absence or presence of a TGF receptor 1 inhibitor. mRNA and protein expression of extracellular matrix components and other fibrosis-related mediators were measured by quantitative PCR and western blot.ResultsExogenous SPARC induced mRNA and protein expression of collagen I, collagen IV, fibronectin 1, TGF-β and SPARC by dermal fibroblasts from SSc patients, but not from healthy controls. Importantly, exogenous SPARC induced the activation of the tyrosine kinase SMAD2 and pro-fibrotic gene expression induced by SPARC in SSc fibroblasts was abrogated by inhibition of TGF-β signalling.ConclusionThese results indicate that exogenous SPARC is an important pro-fibrotic mediator contributing to the pathology driving SSc but in a TGF-β dependent manner. Therefore, SPARC could be a promising therapeutic target for reducing fibrosis in SSc patients, even in late states of the disease.

P1626MicroRNA-21 deteriorates left ventricular reverse remodeling by promoting cardiac fibrosis in non-ischemic cardiomyopathy

Abstract Background Left ventricular reverse remodeling (LVRR) contributes to better outcomes in patients with non-ischemic cardiomyopathy (NICM). It is reported that LVRR is associated with progression of cardiac fibrosis. MicroRNAs (miRs) have emerged as powerful regulators of post-transcriptional gene expression. We focused on miR-21, which plays a key role in pathogenesis of fibrosis in multiple organs. The aim of this study was to clarify the effect of miR-21 on cardiac fibrosis and LVRR in patients with NICM. Methods We measured plasma miR-21 levels in 16 patients with NICM. LVRR was defined as increased LVEF by ≥10% and decreased LV end-diastolic diameter index by ≥10% from baseline data after optimal medication treatment at 1-year of follow-up. Further, we examined miR-21 expression and its potential role in cardiac fibrosis induced by transverse aortic constriction (TAC) in mice and angiotensin II (Ang II) stimulation in neonatal rat cardiomyocytes (NRCMs). Results There were 12 patients without LVRR and 4 patients with LVRR. Plasma miR-21 levels were significantly higher in patients without LVRR compared with those with LVRR. In TAC mice heart, miR-21 levels were significantly increased and programmed cell death 4 (PDCD4), a main target of miR-21, was decreased. In vitro, miR-21 levels were significantly increased and its upstream transcriptional factor, activator protein 1 (AP-1), was activated by Ang II stimulation in NRCMs. After transfection of miR-21 specific inhibitor, PDCD4 levels were upregulated. Furthermore, AP-1 activity, expression of collagen type I, and α-smooth muscle actin levels were significantly decreased after miR-21 inhibition. Conclusions These findings suggested that miR-21/PDCD4/AP-1 feedback loop pathway was involved in LVRR in patients with NICM by promoting cardiac fibrosis. MiR-21 can be the therapeutic target in NICM.

Ephrins and Eph Receptor Signaling in Tissue Repair and Fibrosis.

Fibrosis is a pathological feature of many human diseases that affect multiple organs. The development of anti-fibrotic therapies has been a difficult endeavor due to the complexity of signaling pathways associated with fibrogenic processes, complicating the identification and modulation of specific targets. Evidence suggests that ephrin ligands and Eph receptors are crucial signaling molecules that contribute to physiological wound repair and the development of tissue fibrosis. Here, we discuss recent advances in the understanding of ephrin and Eph signaling in tissue repair and fibrosis. Ephrin-B2 is implicated in fibrosis of multiple organs. Intercepting its signaling may help counteract fibrosis. Ephrins and Eph receptors are candidate mediators of fibrosis. Ephrin-B2, in particular, promotes fibrogenic processes in multiple organs. Thus, therapeutic strategies targeting Ephrin-B2 signaling could yield new ways to treat organ fibrosis.

Galectin-3 Expression in the Left Ventricular Interstitium of Dogs with Chronic Heart Failure: Association with Interstitial Fibrosis

Purpose Accumulation of collagen in the cardiac interstitium termed “reactive interstitial fibrosis (RIF)” occurs in heart failure (HF) with reduced ejection fraction (HFrEF) as well as in HF with preserved EF (HFpEF). This maladaptation leads to increased myocardial stiffness that negatively impacts ventricular filling. RIF also results in poor oxygen diffusion between capillaries and cardiomyocytes leading to cardiomyocyte hypoxia that promotes cellular contractile dysfunction and triggers programmed cell death. The protein galectin-3 (GAL-3) is a member of the lectin family. Increased expression of GAL-3 is implicated in the development of fibrosis in multiple organs including the heart. Elevated levels of GAL-3 are significantly associated with higher risk of death in patients with HF. In this study, we examined whether increased expression of GAL-3 occurs in the LV interstitium of dogs with chronic HF that also manifest increased levels of RIF. Methods Studies were performed in LV tissue obtained from 7 normal (NL) dogs and 7 dogs with coronary microembolization-induced HF. Frozen LV sections, 6 µm in thickness, were used for fluorescence immunostaining with antibodies against myosin heavy chain and GAL-3. DAPI (4′, 6-diamidino-2-phenylindole) was used to stain nuclei. Confocal images of stained sections were obtained with an Olympus Fluoview FV1000 laser scanning biological microscope. From each section, 4-6 fields, each ∼10 mm2, were randomly selected for laser scanning and subsequently used to calculate the percent area occupied by GAL-3 (%aGAL-3) from each field. The percent area occupied by RIF (%aRIF) was also calculated using frozen sections stained with fluorescein-labeled peanut agglutinin. Results In NL dogs, the %aRIF was 3.70 ± 0.07 and %aGAL-3 was 2.40 ± 0.45. In dogs with HF, the %aRIF increased significantly to 13.5 ± 0.57 (p Conclusion The results indicate that in dogs with HF, increased levels of RIF is associated with increased interstitial levels of GAL-3. The findings support the use of this dog model of HF to evaluate the effects of GAL-3 inhibitors for preventing or attenuating RIF that develops during the evolution of HF.

Fibroblast-specific integrin-alpha V differentially regulates type 17 and type 2 driven inflammation and fibrosis.

Fibroproliferative diseases affect a significant proportion of the world's population. Despite this, core mechanisms driving organ fibrosis of diverse etiologies remain ill defined. Recent studies suggest that integrin-alpha V serves as a master driver of fibrosis in multiple organs. Although diverse mechanisms contribute to the progression of fibrosis, TGF-β and IL-13 have emerged as central mediators of fibrosis during type 1/type 17, and type 2 polarized inflammatory responses, respectively. To investigate if integrin-alpha V interactions or signaling is critical to the development of type 2 fibrosis, we analyzed fibroblast-specific integrin-alpha V knockout mice in three type 2-driven inflammatory disease models. While we confirmed a role for integrin-alpha V in type 17-associated fibrosis, integrin-alpha V was not critical to the development of type 2-driven fibrosis. Additionally, our studies support a novel mechanism through which fibroblasts, via integrin-alpha V expression, are capable of regulating immune polarization. We show that when integrin-alpha V is deleted on fibroblasts, initiation of type 17 inflammation is inhibited leading to a deregulation of type 2 inflammation. This mechanism is most evident in a model of severe asthma, which is characterized by a mixed type 2/type 17 inflammatory response. Together, these findings suggest dual targeting of integrin-alpha V and type 2 pathways may be needed to ameliorate fibrosis and prevent rebound of opposing pro-fibrotic and inflammatory mechanisms. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

The Hypomorphic Gata1low Mutation Induces Fibrosis in Multiple Organs

Mice carrying the hypomorphic mutation which reduces the transcription factor GATA1 in megakaryocytes (Gata1low mice), develop by 8-months myelofibrosis a phenotype resembling primary myelofibrosis, the most severe of myeloproliferative neoplasms (Vannucchi et al Blood 2002;100:1123). The high levels of TGF-β expressed by the abnormal Gata1low megakaryocytes that drive myelofibrosis in these mice alter the bone marrow (BM) expression profiling up-regulating expression of the transcription factor c-Jun (Ciaffoni et al BCD 2015; 54:234). Recently, Dr. Weissman reported that c-Jun over-expression in response to TGF-β activation induces in mice fibrosis in multiple organs (Werning et al PNAS 2017, 114, 4757), suggesting that also Gata1low mice may develop multi-organ fibrosis. To test this hypothesis, we compared morphology (by haematoxylin-eosin staining) and fibrosis (reticulin fibres by trichrome Mallory and collagen fibres by Gomory or Sirius Red Picrate staining) of organs from Gata 1low and wild-type (WT) mice at 1-, 8- and 15-months of age (3 mice/group).With age, the organs from WT mice presented histological abnormalities consistent with the mild one expected for being associated with aging and were seldom positive for fibrosis. By contrast, all the organs from Gata1low mice analysed had profound abnormal morphologies with reticulin or collagen fibers detectable, in addition to BM and spleen, in skin, lung, and kidney in an age-specific fashion (Fig 1). Gata1lowskin was thicker than normal and the connective layer presented numerous reticulin strikes already by 1-month and heavily dense connective regions strongly positive for collagen fibres by 8-15 months, resembling the skin from scleroderma patients. In lung, the alveoli had thickened walls with reticulin fibers detectable by 8-months and collagen bundles by 15-months near the bronchus walls. The abnormal morphology of kidney included reduced numbers of glomeruli and poorly organized cortical parenchyma. Reticulin and collagen fibres were observed in the medullary and nephron region by 8- and 15-months, respectively. In heart, cardiomyocytes presented a strong reduction of intercalary disks by 8-months and reticulin fibers were detectable at 15-months, suggesting that this mild fibrosis is driven by lung insufficiency. The liver presented abnormal localization and morphology of hepatocytes and presence of extramedullary hematopoiesis in perisinusoid areas. Sirius Red Picrate staining revealed few reticulin fibres mostly within erythroid islands.To clarify the mechanisms leading to multi-organ fibrosis in Gata1low mice, the transcription signature of 8-months Gata1low BM was compared with that published for murine liver, lung and kidney fibrosis (https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi? token = ijgpwgsyjhwpdoj&acc = GSE89630). Gata1low BM presented abnormal expression of 1724 genes (821 up- and 903 down). Pathway analyses indicated that most of the down genes were in the Gata1 pathway while the most prominent up genes were in the c-Jun, EZH2, SCL and p53 pathways. Some of the gene abnormal in Gata1low BM were also abnormal in liver (64), lung (29) and kidney (432) fibrosis. Only 28 genes were abnormal in more than one organ (25 liver and kidney, 7 lung). These common genes were obvious markers for fibrosis (5 collagen genes, fibronectin, TGF-β) and did not include c-Jun. Among genes up in Gata1low BM, kidney and liver there was lipocalin 2 (LCN2), a growth factor overexpressed in primary myelofibrosis patients (Lu et al Blood 2015;126:972) that exerts positive and negative effects, respectively, on fibrosis in BM and liver. By comparing the plasma levels of LCN2 in Gata1low and WT mice at 8-9 -and 15-17-months (8-29 mice/group), we determined that levels of LNC2 do not change with age in WT mice but increase by 3-fold in old Gata1low mice (p=0.028), explaining why liver was not one of the organs in which the mutants develop fibrosis.In conclusion, in addition to myelofibrosis, Gata1low mice develop fibrosis in skin, lung and kidney but not in heart and liver and represent genetic models for studies on the pathogenesis of fibrosis in multiple organs. Moreover, these results suggest that although the initiation factor(s) for fibrosis in the various organs are likely different, most of them are expressed by Gata1low megakaryocytes highlighting the importance for studies on the secretome profile of these cells. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

IL-17A Promotes Initiation and Development of Intestinal Fibrosis Through EMT.

Intestinal fibrosis is a common complication of Crohn's disease (CD). Its exact mechanism is still unclear, and effective treatments to control or reverse the fibrosis process are unavailable. Epithelial-mesenchymal transition (EMT) may promote intestinal fibrosis by increasing deposition of extracellular matrix protein. IL-17A is a pro-inflammatory cytokine, and it has been shown as a profibrotic factor as its association with fibrosis of multiple organs was reported. To assess the roles of IL-17A and EMT in the initiation and development of intestinal fibrosis and to verify the potential inductive effect of IL-17A on EMT. In this study, we evaluated the expression of IL-17A and EMT-related genes in colonic mucosal biopsy tissues of CD patients and control individuals. Then, we examined the changes of EMT-related genes and fibrosis-related genes of IEC-6 cells which cultured for 72h under increasing concentrations of IL-17A or with TGF-β1, to verify the potential inductive effect of IL-17A on EMT in vitro. We blocked the IL-17A of the mouse model of TNBS-induced experimental intestinal colitis and fibrosis to further verify the potential inductive effect of IL-17A on EMT in vivo. We found the occurrence of EMT and high-level expression of IL-17A in intestinal mucosa of CD patients. Using IEC-6 cells, we showed that IL-17A may induce EMT in intestinal epithelial cells that come with reduced E-cadherin expression and increased expression of vimentin, snail, and α-SMA. We further found that anti-IL-17A treatment alleviated intestinal fibrosis through reducing EMT in mouse intestine. Our study confirmed the involvement of IL-17A in the development of intestinal fibrosis through inducing EMT.

The Antifibrotic Effect of A2B Adenosine Receptor Antagonism in a Mouse Model of Dermal Fibrosis.

Systemic sclerosis (SSc; scleroderma) is a chronic disease that affects the skin and various internal organs. Dermal fibrosis is a major component of this disease. The mechanisms that promote dermal fibrosis remain elusive. Elevations in tissue adenosine levels and the subsequent engagement of the profibrotic A2B adenosine receptor (ADORA2B) have been shown to regulate fibrosis in multiple organs including the lung, kidney, and penis; however, the role of ADORA2B in dermal fibrosis has not been investigated. We undertook this study to test our hypothesis that elevated expression of ADORA2B in the skin drives the development of dermal fibrosis. We assessed the involvement of ADORA2B in the regulation of dermal fibrosis using a well-established mouse model of dermal fibrosis. Using an orally active ADORA2B antagonist, we demonstrated how inhibition of ADORA2B results in reduced dermal fibrosis in 2 distinct experimental models. Finally, using human dermal fibroblasts, we characterized the expression of adenosine receptors. We demonstrated that levels of ADORA2B were significantly elevated in dermal fibrosis and that the therapeutic blockade of this receptor in vivo using an ADORA2B antagonist could reduce the production of profibrotic mediators in the skin and attenuate dermal fibrosis. Antagonism of ADORA2B resulted in reduced numbers of arginase-expressing macrophages and myofibroblasts and in reduced levels of the extracellular matrix proteins fibronectin, collagen, and hyaluronan. These findings identify ADORA2B as a potential profibrotic regulator in dermal fibrosis and suggest that ADORA2B antagonism may be a useful approach for the treatment of SSc.

TLR4-dependent fibroblast activation drives persistent organ fibrosis in skin and lung.

Persistent fibrosis in multiple organs is the hallmark of systemic sclerosis (SSc). Recent genetic and genomic studies implicate TLRs and their damage-associated molecular pattern (DAMP) endogenous ligands in fibrosis. To test the hypothesis that TLR4 and its coreceptor myeloid differentiation 2 (MD2) drive fibrosis persistence, we measured MD2/TLR4 signaling in tissues from patients with fibrotic SSc, and we examined the impact of MD2 targeting using a potentially novel small molecule. Levels of MD2 and TLR4, and a TLR4-responsive gene signature, were enhanced in SSc skin biopsies. We developed a small molecule that selectively blocks MD2, which is uniquely required for TLR4 signaling. Targeting MD2/TLR4 abrogated inducible and constitutive myofibroblast transformation and matrix remodeling in fibroblast monolayers, as well as in 3-D scleroderma skin equivalents and human skin explants. Moreover, the selective TLR4 inhibitor prevented organ fibrosis in several preclinical disease models and mouse strains, and it reversed preexisting fibrosis. Fibroblast-specific deletion of TLR4 in mice afforded substantial protection from skin and lung fibrosis. By comparing experimentally generated fibroblast TLR4 gene signatures with SSc skin biopsy gene expression datasets, we identified a subset of SSc patients displaying an activated TLR4 signature. Together, results from these human and mouse studies implicate MD2/TLR4-dependent fibroblast activation as a key driver of persistent organ fibrosis. The results suggest that SSc patients with high TLR4 activity might show optimal therapeutic response to selective inhibitors of MD2/TLR4 complex formation.

Glucocorticoid receptor expression in resident and hematopoietic cells in IgG4-related disease

AbstractImmunoglobulin G4-related disease is a rare immune-mediated disease characterized by the infiltration of IgG4-positive plasma cells and unique storiform fibrosis of multiple organs. The majority of IgG4-related disease patients respond to glucocorticoids, yet the precise mechanism of their action remains unclear. Pathological sections of the submaxillary gland, kidney, and retroperitoneum from 20 patients in total diagnosed with IgG4-related disease were analyzed for glucocorticoid receptor expression and the cell types expressing glucocorticoid receptor. Strong and abundant expression of glucocorticoid receptor was observed in the submaxillary gland, kidney, and retroperitoneum of IgG4-related disease patients, while glucocorticoid receptor was rarely or only faintly observed in the submaxillary gland of patients with Sjögren's syndrome, radicular cysts and sialolithiasis or in the healthy kidney. Glucocorticoid receptor was mainly expressed in fibro/myofibroblasts, CD4-positive T cells and IgG4-positive plasma cells in the submandibular glands and kidneys of IgG4-related disease patients. The abundant expression of glucocorticoid receptor in various types of cells, including resident fibro/myofibroblasts in IgG4-related disease patients might provide clues to the mechanism of steroid responsiveness in IgG4-related disease patients.

The effect of spironolactone on calcineurin inhibitor induced nephrotoxicity: a multicenter randomized, double-blind, clinical trial (the SPIREN trial)

BackgroundCalcineurin inhibitor induced nephrotoxicity contributes to late allograft failure in kidney transplant patients. Evidence points towards aldosterone to play a role in the development of fibrosis in multiple organs. Animal studies have indicated a beneficial effect of mineralocorticoid receptor antagonists preventing calcineurin inhibitor induced nephrotoxicity. Only few studies have explored this effect in humans. The objective of this study is to evaluate the effect of spironolactone on glomerular filtration rate and fibrosis in kidney transplant patients.MethodProspective, double-blind, randomized, clinical trial including 170 prevalent kidney transplant patients. Patients are randomized to spironolactone 25–50 mg/day or placebo for three years. Primary outcome is glomerular filtration rate evaluated by chrome-EDTA clearance. Secondary outcomes are 24-h protein excretion, amount of interstitial fibrosis in renal allograft biopsies, and cardiovascular events. As an exploratory outcome, we aim to identify markers of fibrosis in blood and urine.DiscussionLong term allograft survival remains a key issue in renal transplantation, partly due to calcineurin inhibitor induced nephrotoxicity. Evidence from animal- and small human studies indicate a beneficial effect of mineralocorticoid receptor antagonism on renal function and fibrosis. This study aims to test this hypothesis in a sufficiently powered randomized clinical trial. Results might influence the future management of long term allograft survival in renal transplantation.Trial registrationClinicalTrials.gov identifier (05/17/2012): NCT01602861. EudraCT number (05/31/2011): 2011–002243-98.

Rapamycin Protects Against Peritendinous Fibrosis Through Activation of Autophagy.

Dysregulation of autophagy plays a pivotal role in fibrosis in multiple organs. However, the role of autophagy in peritendinous fibrosis is not well understood. Here, we hypothesize that autophagy plays a protective role in preventing adhesion formation. In a rat model of tendon injury, we observed dysregulated autophagy during excessive extracellular matrix deposition. Pharmacological induction of autophagy by rapamycin markedly alleviated the severity of peritendinous fibrosis in vivo. In NIH/3T3 fibroblasts and tenocytes, transforming growth factor β1 (TGF-β1) markedly activated myofibroblasts and increased collagen synthesis. Addition of rapamycin activated autophagy, reduced collagen synthesis, and suppressed myofibroblast activation. In vitro experiments also showed that rapamycin decreased cell proliferation and increased the number of cells arrested in G0/G1 phase. However, following pretreatment with the autophagy inhibitor 3-methyladenine (3-MA), rapamycin was unable to repress the fibrotic changes induced by TGF-β1. Autophagy related protein 5 (Atg5) RNA interference in fibroblasts also abolished the protective effects of rapamycin in vitro. In conclusion, our results point to rapamycin as a potential treatment strategy in the prevention of peritendinous fibrosis after tendon injury.

Parathyroid Hormone–Like Hormone Induces Epithelial-to-Mesenchymal Transition of Intestinal Epithelial Cells by Activating the Runt-Related Transcription Factor 2

Epithelial-to-mesenchymal transition (EMT) is a key contributor to fibroblast activation in fibrosis of multiple organs, including the intestine. Parathyroid hormone-like hormone (PTHLH) is an important factor in renal fibrosis and regulates several processes, including EMT. Herein, we investigated the role of PTHLH-induced EMT in intestinal fibrosis associated with Crohn disease. The expression levels of the EMT-related proteins, PTHLH, and parathyroid hormone receptor 1 (PTH1R) in intestinal tissues were determined by immunohistochemistry, and our results revealed that PTHLH and PTH1R were significantly elevated and associated with EMT marker expression. Moreover, neutralizing PTH1R and antagonizing PTHLH bioactivity prevented transforming growth factor-β1-induced EMT. PTH1R can propagate the protein kinase A (PKA) signal and activate downstream nuclear transcription factors, including runt-related transcription factor 2 (Runx2). In addition, lentiviral vector-PTHLH-treated mice were highly sensitive to 2,4,6-trinitrobenzene sulfonic acid, and analysis of the PTHLH-PTH1R axis revealed the involvement of PKA-Runx2 in PTHLH-induced EMT. Our results indicate that PTHLH triggered EMT in intestinal epithelial cells through the PKA-Runx2 pathway, which might serve as a therapeutic target for intestinal fibrosis in Crohn disease.

MicroRNA‐21 and Dicer are dispensable for hepatic stellate cell activation and the development of liver fibrosis

Genetic and pharmacologic manipulation of miR-21 does not inhibit the development of liver fibrosis and liver cancer. Moreover, suppression of microRNA synthesis does not significantly affect HSC phenotype and activation. (Hepatology 2018;67:2414-2429).

Macrophage polarization and function: new prospects for fibrotic disease.

Fibrosis is commonly regarded as a pathological and dynamic process with the hallmarks of chronic inflammation and wound healing. Emerging evidence indicates that heterogeneous monocyte-macrophage lineage cells are indispensable for mounting either pro-fibrotic or anti-fibrotic responses in different stages during fibrotic pathogenesis. This review highlights the evolving roles of macrophage polarization and functions linked to fibrosis in multiple organs. In the future, identifying the molecular and cellular factors that influence the macrophage phenotypic balance may provide novel therapeutic approaches for fibrotic diseases.

A modified graft-versus-host-induced model for systemic sclerosis, with pulmonary fibrosis in Rag2-deficient mice.

Systemic sclerosis (SSc) is a connective tissue disease that results in fibrosis in multiple organs. Various animal models for this disease have been developed, both genetic and induced. One of the induced models, sclerodermatous graft‐versus‐host disease (scl‐GvHD), exhibits the main characteristics of SSc, but involves lethal γ‐irradiation of recipients. We sought to develop a modified scl‐GvHD model. Spleen cells from B10.D2 donor mice were transplanted into immunodeficient Rag‐2 recipients on the BALB/c genetic background. Tissue fibrosis was analyzed at 3 and 9 weeks after transplantation. In addition to serum levels of anti‐Scl‐70 autoantibody and cytokines, tissue inflammation, fibrosis, expression of collagen‐I and α‐smooth muscle actin (α‐SMA), infiltration of leukocytes, mRNA expression of transforming growth factor (TGF)‐β, collagen‐I, α‐SMA, tumor necrosis factor (TNF)‐α, and interleukin (IL)‐6, the classical signal pathway of TGF‐β, Smad‐3, and p‐Smad‐3 expression in tissue were analyzed. Skin thickening and increased collagen synthesis, as well as the manifestation of tissue fibrosis, could be detected in skin, kidney, and lung of modified scl‐GvHD mouse model. Increased serum levels of anti‐Scl‐70 autoantibody, IL‐10, and TGF‐β could be detected. Increased CD4+ T cells and F4/80+ macrophage infiltration were found in skin, kidney, and lung. Gene expression of collagen‐I, TGF‐β, α‐SMA, TNF‐α, and IL‐6 was increased in tissue of the scl‐GvHD model. Moreover, TGF‐β expression and Smad‐3 phosphorylation were detected in skin, kidney, and lung of scl‐GvHD mice. Our data show that spleen cells from B10.D2 donor mice transplanted into immunodeficient Rag‐2 recipients could induce typical fibrosis not only of the skin and kidney but also of lung, which was missing from previous scl‐GvHD models. Thus, the modified scl‐GvHD model might be a promising model to explore the immunologic mechanisms of SSc and may be useful for investigation of new therapies for systemic sclerosis.

Phototherapy in systemic sclerosis: Review.

Systemic scleroderma-also known as systemic sclerosis (SSc)-is a chronic systemic connective tissue disease characterized by collagen deposition in cutaneous and internal organs, leading to skin sclerosis and multiple organ fibrosis. The pathogenesis is complex and remains poorly understood. Treatment is based on organ involvement and requires a multidisciplinary approach. Skin sclerosis can cause disability, leading to decreasing quality of life. Various systemic antifibrotic therapies have been used; however, most have unsatisfactory results. Recently, phototherapy and in particular ultraviolet A (UVA) has been used to treat skin sclerosis in SSc patients with satisfactory results. The main mechanisms include lymphocyte apoptosis, cytokine alteration, inhibition of collagen synthesis and increased collagenase production, and neovascularization, leading to the breakdown of collagen fibrils resulting in skin softening or even healing digital ulcers. Most studies reported that psoralen plus UVA (PUVA) and UVA1 phototherapy improved clinical outcomes vis-à-vis skin sclerosis, joint mobility, ulcers, and histopathology. PUVA and UVA1 phototherapy therefore have potential as an alternative or adjunctive therapy for patients with SSc.

The role of endothelial cells in the vasculopathy of systemic sclerosis: A systematic review.

Systemic sclerosis (SSc) is an autoimmune connective tissue disorder characterized by fibroproliferative vasculopathy, immunological abnormalities and progressive fibrosis of multiple organs including the skin. In this study, all English speaking articles concerning the role of endothelial cells (ECs) in SSc vasculopathy and representing biomarkers are systematically reviewed and categorized according to endothelial cell (EC) (dys)function in SSc. A sensitive search on behalf of the EULAR study group on microcirculation in Rheumatic Diseases was developed in Pubmed, The Cochrane Library and Web of Science to identify articles on SSc vasculopathy and the role of ECs using the following Mesh terms: (systemic sclerosis OR scleroderma) AND pathogenesis AND (endothelial cells OR marker). All selected papers were read and discussed by two independent reviewers. The selection process was based on title, abstract and full text level. Additionally, both reviewers further searched the reference lists of the articles selected for reading on full text level for supplementary papers. These additional articles went through the same selection process. In total 193 resulting articles were selected and the identified biomarkers were categorized according to description of EC (dys)function in SSc. The most representing and reliable biomarkers described by the selected articles were adhesion molecules for EC activation, anti-endothelial cell antibodies for EC apoptosis, vascular endothelial growth factor (VEGF), its receptor VEGFR-2 and endostatin for disturbed angiogenesis, endothelial progenitors cells for defective vasculogenesis, endothelin-1 for disturbed vascular tone control, Von Willebrand factor for coagulopathy and interleukin (IL)-33 for EC-immune system communication. Emerging, relatively new discovered biomarkers described in the selected articles, are VEGF165b, IL-17A and the adipocytokines. Finally, myofibroblasts involved in tissue fibrosis in SSc can derive from ECs or epithelial cells through a process known as endothelial-to-mesenchymal transition. This systematic review emphasizes the growing evidence that SSc is primarily a vascular disease where EC dysfunction is present and prominent in different aspects of cell survival (activation and apoptosis), angiogenesis and vasculogenesis and where disturbed interactions between ECs and various other cells contribute to SSc vasculopathy.

Unifying mechanism for different fibrotic diseases

Fibrotic diseases are not well-understood. They represent a number of different diseases that are characterized by the development of severe organ fibrosis without any obvious cause, such as the devastating diseases idiopathic pulmonary fibrosis (IPF) and scleroderma. These diseases have a poor prognosis comparable with endstage cancer and are uncurable. Given the phenotypic differences, it was assumed that the different fibrotic diseases also have different pathomechanisms. Here, we demonstrate that many endstage fibrotic diseases, including IPF; scleroderma; myelofibrosis; kidney-, pancreas-, and heart-fibrosis; and nonalcoholic steatohepatosis converge in the activation of the AP1 transcription factor c-JUN in the pathologic fibroblasts. Expression of the related AP1 transcription factor FRA2 was restricted to pulmonary artery hypertension. Induction of c-Jun in mice was sufficient to induce severe fibrosis in multiple organs and steatohepatosis, which was dependent on sustained c-Jun expression. Single cell mass cytometry revealed that c-Jun activates multiple signaling pathways in mice, including pAkt and CD47, which were also induced in human disease. αCD47 antibody treatment and VEGF or PI3K inhibition reversed various organ c-Jun-mediated fibroses in vivo. These data suggest that c-JUN is a central molecular mediator of most fibrotic conditions.