Fabian A. Mendoza

Strategies for anti-fibrotic therapies.

The fibrotic diseases encompass a wide spectrum of entities including such multisystemic diseases as systemic sclerosis, nephrogenic systemic fibrosis and sclerodermatous graft versus host disease, as well as organ-specific disorders such as pulmonary, liver, and kidney fibrosis. Collectively, given the wide variety of affected organs, the chronic nature of the fibrotic processes, and the large number of individuals suffering their devastating effects, these diseases pose one of the most serious health problems in current medicine and a serious economic burden to society. Despite these considerations there is currently no accepted effective treatment. However, remarkable progress has been achieved in the elucidation of their pathogenesis including the identification of the critical role of myofibroblasts and the determination of molecular mechanisms that result in the transcriptional activation of the genes responsible for the fibrotic process. Here we review the origin of the myofibroblast and discuss the crucial regulatory pathways involving multiple growth factors and cytokines that participate in the pathogenesis of the fibrotic process. Potentially effective therapeutic strategies based upon this new information are considered in detail and the major challenges that remain and their possible solutions are presented. It is expected that translational efforts devoted to convert this new knowledge into novel and effective anti-fibrotic drugs will be forthcoming in the near future. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Endothelial to Mesenchymal Transition (EndoMT) in the Pathogenesis of Human Fibrotic Diseases

Fibrotic diseases encompass a wide spectrum of clinical entities including systemic fibrotic diseases such as systemic sclerosis, sclerodermatous graft versus host disease, nephrogenic systemic fibrosis, and IgG4-associated sclerosing disease, as well as numerous organ-specific disorders including radiation-induced fibrosis, and cardiac, pulmonary, liver, and kidney fibrosis. Although their causative mechanisms are quite diverse, these diseases share the common feature of an uncontrolled and progressive accumulation of fibrous tissue macromolecules in affected organs leading to their dysfunction and ultimate failure. The pathogenesis of fibrotic diseases is complex and despite extensive investigation has remained elusive. Numerous studies have identified myofibroblasts as the cells responsible for the establishment and progression of the fibrotic process. Tissue myofibroblasts in fibrotic diseases originate from several sources including quiescent tissue fibroblasts, circulating CD34+ fibrocytes, and the phenotypic conversion of various cell types including epithelial and endothelial cells into activated myofibroblasts. However, the role of the phenotypic transition of endothelial cells into mesenchymal cells (Endothelial to Mesenchymal Transition or EndoMT) in the pathogenesis of fibrotic disorders has not been fully elucidated. Here, we review the evidence supporting EndoMT’s contribution to human fibrotic disease pathogenesis.

A Prospective Observational Study of Mycophenolate Mofetil Treatment in Progressive Diffuse Cutaneous Systemic Sclerosis of Recent Onset

Objective. A prospective observational study of mycophenolate mofetil (MMF) treatment in patients with diffuse progressive cutaneous systemic sclerosis (SSc) of recent onset. Methods. Twenty-five previously untreated consecutive patients with recent-onset (< 24 mo) diffuse progressive cutaneous SSc received MMF as the only disease-modifying therapy. Modified Rodnan skin score (mRSS) and affected body surface area (BSA) were compared from initiation of MMF to study end. Pulmonary function tests performed at the same institution before therapy and at study end were available in 15 patients. Histopathology and real-time PCR assessment of fibrosis-related gene expression were performed before and after treatment in skin biopsies from 3 patients. Results. At 18.2 ± 8.73 months of MMF therapy (median 2000 mg/day) the mRSS decreased from 24.56 ± 8.62 to 14.52 ± 10.9 (p = 0.0004) and the affected BSA from 36% ± 16% to 14% ± 13.3% (p = 0.00001). Pulmonary function tests remained stable from initiation of MMF to the end of the study. Skin histopathology showed a remarkable reduction in accumulation of fibrotic tissue. Real-time PCR of skin biopsies demonstrated a marked decrease in expression of fibrosis-related genes. Conclusion. Patients with diffuse progressive cutaneous SSc of recent onset treated with MMF experienced marked improvement in skin involvement and stabilization of pulmonary function. Skin biopsies from 3 patients demonstrated histopathological improvement and decreased expression of fibrosis-related genes.

Endothelial Cells Expressing Endothelial and Mesenchymal Cell Gene Products in Lung Tissue From Patients With Systemic Sclerosis-Associated Interstitial Lung Disease.

To examine whether lung endothelial cells (ECs) from patients with systemic sclerosis (SSc)–associated interstitial lung disease (ILD) express mesenchymal cell–specific proteins and gene transcripts, indicative of the occurrence of endothelial‐to‐mesenchymal phenotypic transition (EndoMT).

Endothelial cells expressing endothelial and mesenchymal cell gene products in Systemic Sclerosis‐associated interstitial lung disease lung tissues

To examine whether lung endothelial cells (ECs) from patients with systemic sclerosis (SSc)–associated interstitial lung disease (ILD) express mesenchymal cell–specific proteins and gene transcripts, indicative of the occurrence of endothelial‐to‐mesenchymal phenotypic transition (EndoMT).

Stimulation of Transforming Growth Factor-β1-Induced Endothelial-To-Mesenchymal Transition and Tissue Fibrosis by Endothelin-1 (ET-1): A Novel Profibrotic Effect of ET-1.

TGF-β-induced endothelial-to-mesenchymal transition (EndoMT) is a newly recognized source of profibrotic activated myofibroblasts and has been suggested to play a role in the pathogenesis of various fibrotic processes. Endothelin-1 (ET-1) has been implicated in the development of tissue fibrosis but its participation in TGF-β-induced EndoMT has not been studied. Here we evaluated the role of ET-1 on TGF-β1-induced EndoMT in immunopurified CD31+/CD102+ murine lung microvascular endothelial cells. The expression levels of α-smooth muscle actin (α-SMA), of relevant profibrotic genes, and of various transcription factors involved in the EndoMT process were assessed employing quantitative RT-PCR, immunofluorescence histology and Western blot analysis. TGF-β1 caused potent induction of EndoMT whereas ET-1 alone had a minimal effect. However, ET-1 potentiated TGF-β1-induced EndoMT and TGF-β1-stimulated expression of mesenchymal cell specific and profibrotic genes and proteins. ET-1 also induced expression of the TGF-β receptor 1 and 2 genes, suggesting a plausible autocrine mechanism to potentiate TGF-β-mediated EndoMT and fibrosis. Stimulation of TGF-β1-induced skin and lung fibrosis by ET-1 was confirmed in vivo in an animal model of TGF-β1-induced tissue fibrosis. These results suggest a novel role for ET-1 in the establishment and progression of tissue fibrosis.

Effects of scleroderma antibodies and pooled human immunoglobulin on anal sphincter and colonic smooth muscle function.

BACKGROUND & AIMS Patients with systemic sclerosis (SSc) have impairments in gastrointestinal smooth muscle function. The disorder has been associated with circulating antibodies to cholinergic muscarinic the type-3 receptor (M(3)-R). We investigated whether it is possible to neutralize these antibodies with pooled human IgGs (pooledhIgG). METHODS We studied the effects of IgGs purified from patients with SSc (SScIgGs) on cholinergic nerve stimulation in rat colon tissues. We also examined the effects of SScIgGs on M(3)-R activation by bethanechol (BeCh), M(3)-R occupancy, and receptor binding using immunofluorescence, immunoblot, and enzyme-linked immunosorbent analyses of human internal anal sphincter (IAS) smooth muscle cells, before and after administration of pooledhIgG. Functional displacement of M(3)-R occupancy by the SScIgGs was compared with that of other IgGs during the sustained phase of BeCh-induced contraction of intact smooth muscles from rats. RESULTS SScIgG significantly attenuated neurally mediated contraction and acetylcholine release in rat colon as well as BeCh-induced sustained contraction of the IAS smooth muscle. In immunofluorescence analysis, SScIgG co-localized with M(3)-R. In immunoblot and enzyme-linked immunosorbent analyses, M(3)-R loop-2 peptide and human IAS SMC membrane lysates bound significant amounts of SScIgG, compared with IgGs from healthy individuals and pooledhIgG. Binding was attenuated significantly by application of pooledhIgG, which by itself had no significant effect. Incubation of samples with pooledhIgG, or mixing pooledhIgG with SScIgG before administration to tissues, significantly reduced binding of SScIgG, indicating that pooledhIgG prevents SScIgG blockade of M(3)-R. CONCLUSIONS In studies of rat and human tissues, pooled human IgG prevent and reverses the cholinergic dysfunction associated with the progressive gastrointestinal manifestations of SSc by neutralizing functional M(3)-R antibodies present in the circulation of patients with SSc.

Treatment of rapidly progressive systemic sclerosis: current and futures perspectives

Introduction: Systemic sclerosis (SSc) is a systemic autoimmune disease characterized by severe and often progressive cutaneous, pulmonary, cardiac and gastrointestinal tract fibrosis, cellular and humoral immunologic alterations, and pronounced fibroproliferative vasculopathy. There is no effective SSc disease modifying therapy. Patients with rapidly progressive SSc have poor prognosis with frequent disability and very high mortality. Areas covered: This paper reviews currently available therapeutic approaches for rapidly progressive SSc and discuss novel drugs under study for SSc disease modification. Expert opinion: The extent, severity and rate of progression of SSc skin and internal organ involvement determines the optimal therapeutic interventions for SSc. Cyclophosphamide for progressive SSc-associated interstitial lung disease and mycophenolate for rapidly progressive cutaneous involvement have shown effectiveness. Methotrexate has been used for less severe skin progression and for patients unable to tolerate mycophenolate. Rituximab was shown to induce improvement in SSc-cutaneous and lung involvement. Autologous bone marrow transplantation is reserved for selected cases in whom poor survival risk outweighs the high mortality rate of the procedure. Novel agents capable of modulating fibrotic and inflammatory pathways involved in SSc pathogenesis, including tocilizumab, pirfenidone, tyrosine kinase inhibitors, lipid lysophosphatidic acid 1 and NOX4 inhibitors are currently under development for the treatment of rapidly progressive SSc.

Severe eosinophilic fasciitis: comparison of treatment with d-penicillamine plus corticosteroids vs. corticosteroids alone

Objectives: To compare the therapeutic effectiveness of corticosteroids (CS) alone vs. CS plus d-penicillamine (d-Pen) in severe eosinophilic fasciitis. Method: A long-term prospective non-randomized trial of d-Pen plus CS vs. CS alone in patients with severe eosinophilic fasciitis, defined as clinically apparent cutaneous fibrotic involvement affecting more than 15% body surface area (BSA) or more than 10% BSA with joint flexion contractures. Results: Sixteen patients with severe eosinophilic fasciitis entered the study. Ten patients received d-Pen plus CS and six received CS alone. Affected BSA decreased from an average of 29% to 8.9% in the d-Pen plus CS group compared to a decrease in affected BSA from 28% to 22.83% in the CS-alone group. The reduction in affected BSA in the d-Pen plus CS group was significantly greater than in the CS-alone group (p = 0.038). Clinical improvement occurred in all d-Pen plus CS patients compared to only 33.3% of CS-alone patients (p = 0.008). There was no difference in overall frequency of adverse events between the groups (p = 0.60). The most common adverse event in the d-Pen plus CS group was proteinuria (33.3%). However, proteinuria also occurred in 16.6% in the CS-alone group. Conclusions: Treatment with CS alone failed to induce clinical improvement in the majority of the severe eosinophilic fasciitis patients. By contrast, d-Pen plus CS resulted in significantly greater clinical improvement. These results suggest that initial treatment of severe eosinophilic fasciitis with CS alone is not sufficient for optimal therapeutic response and that addition of an antifibrotic agent results in an improved outcome.

Systemic sclerosis disease modification clinical trials design: Quo vadis?

The purpose of this manuscript is to discuss relevant aspects of clinical trials for Systemic Sclerosis (SSc) and to identify important considerations for the design of SSc disease modification clinical trials. Placebo randomized controlled trials with appropriate identification of SSc patients with diffuse progressive SSc skin involvement of recent onset, along with a rescue strategy for patients with worsening lung and skin involvement are suggested. If change in skin thickening is a major outcome of the study, the selection of patients with recent onset of disease and a predetermined degree of skin involvement are crucial requirements. The trial duration should be of at least 12 months. Sample size calculations should consider differences that exceed the Minimal Important Difference. Other relevant trial designs and potential threats to study validity are also discussed. Previous SSc-disease modifying trials have been beset by high dropout rates. Analyses on the subset of subjects completing the trial or applying the last-observation-carried-forward approach can potentially lead to biased estimates and false conclusions. Strategies for retention of subjects should be included at the design stage and analyses to account for missing data should be performed.