Inhibition of type I collagen production by dermal fibroblasts upon contact with activated T cells: different sensitivity to inhibition between systemic sclerosis and control fibroblasts

Carcinogenic risk in patients treated with UVA-1 phototherapy: A 5-year retrospective study

BACKGROUND

UVA-1 phototherapy was first used to treat atopic dermatitis and afterwards to several other skin diseases. The contribution of UVA-1 in human photocarcinogenesis, skin photoaging, immune suppression, and hyperpigmentation is now well established. The actual contribution of UVA-1 radiation to the development of malignant melanoma (MM) in humans cannot be excluded.

PURPOSE

The aim of the study is to evaluate the risk of developing skin cancers (non-melanoma skin cancers (NMSCs) and MM) in patients treated with UVA-1 phototherapy with a 5-year dermatological follow-up.

METHODS

We conducted a retrospective cohort study with 31 patients with morphea and atopic dermatitis treated with medium dose UVA-1 phototherapy (34 J/cm2). All enrolled patients underwent an oncologic prevention visit annually with a 5-year follow-up with clinical evaluation of the entire skin surface.

RESULTS

During the 5-year follow-up, we recorded a case of basal cell carcinoma (BCC) in the cervical region and one case of MM on the back (pT1a). In both cases, the patients were female and affected by morphea. The Glogau 3 group is prevalent (42%), which is consistent with moderate to severe aging; the data appear to be compatible with the age.

CONCLUSIONS

This study attests that medium-dose UVA-1 phototherapy does not increase the risk of developing skin tumors and that UVA-1 phototherapy is not a worsening factor of facial photoaging. The main limitation of the study is the small sample size, avoiding to obtain statistically significant values. It was not possible to analyze individually the actual daily sun exposure during the 5-year observation period and to correlate it in terms of time and tumor development. Further studies with large sample sizes will be needed to confirm our data. Our study reaffirms how the dermatological examination performed annually is essential in the follow-up of patients undergoing this type of therapy.

Interrelation Between Fibroblasts and T Cells in Fibrosing Interstitial Lung Diseases

Interstitial lung diseases (ILDs) are a heterogeneous group of diseases characterized by varying degrees of inflammation and fibrosis of the pulmonary interstitium. The interrelations between multiple immune cells and stromal cells participate in the pathogenesis of ILDs. While fibroblasts contribute to the development of ILDs through secreting extracellular matrix and proinflammatory cytokines upon activation, T cells are major mediators of adaptive immunity, as well as inflammation and autoimmune tissue destruction in the lung of ILDs patients. Fibroblasts play important roles in modulating T cell recruitment, differentiation and function and conversely, T cells can balance fibrotic sequelae with protective immunity in the lung. A more precise understanding of the interrelation between fibroblasts and T cells will enable a better future therapeutic design by targeting this interrelationship. Here we highlight recent work on the interactions between fibroblasts and T cells in ILDs, and consider the implications of these interactions in the future development of therapies for ILDs.

Current Concepts on the Pathogenesis of Systemic Sclerosis

From the clinical standpoint, systemic sclerosis (SSc) is characterized by skin and internal organ fibrosis, diffuse fibroproliferative vascular modifications, and autoimmunity. Clinical presentation and course are highly heterogenous and life expectancy variably affected mostly dependent on lung and heart involvement. SSc touches more women than men with differences in disease severity and environmental exposure. Pathogenetic events originate from altered homeostasis favored by genetic predisposition, environmental cues and a variety of endogenous and exogenous triggers. Epigenetic modifications modulate SSc pathogenesis which strikingly associate profound immune-inflammatory dysregulation, abnormal endothelial cell behavior, and cell trans-differentiation into myofibroblasts. SSc myofibroblasts show enhanced survival and enhanced extracellular matrix deposition presenting altered structure and altered physicochemical properties. Additional cell types of likely pathogenic importance are pericytes, platelets, and keratinocytes in conjunction with their relationship with vessel wall cells and fibroblasts. In SSc, the profibrotic milieu is favored by cell signaling initiated in the one hand by transforming growth factor-beta and related cytokines and in the other hand by innate and adaptive type 2 immune responses. Radical oxygen species and invariant receptors sensing danger participate to altered cell behavior. Conventional and SSc-specific T cell subsets modulate both fibroblasts as well as endothelial cell dysfunction. Beside autoantibodies directed against ubiquitous antigens important for enhanced clinical classification, antigen-specific agonistic autoantibodies may have a pathogenic role. Recent studies based on single-cell RNAseq and multi-omics approaches are revealing unforeseen heterogeneity in SSc cell differentiation and functional states. Advances in system biology applied to the wealth of data generated by unbiased screening are allowing to subgroup patients based on distinct pathogenic mechanisms. Deciphering heterogeneity in pathogenic mechanisms will pave the way to highly needed personalized therapeutic approaches.

CD70 Activation Decreases Pulmonary Fibroblast Production of Extracellular Matrix Proteins

Idiopathic pulmonary fibrosis (IPF) is a lethal, medically refractory syndrome characterized by intrapulmonary accumulations of extracellular matrix (ECM) proteins produced by fibroblasts. Activation, clonal expansion, and differentiation of lymphocytes are also frequently present in IPF. Activated T cells are known to exert several effects that promote ECM production, but opposing homeostatic actions, wherein T cells can inhibit fibrosis, are less well understood. We found that CD27, a TNF receptor ubiquitously expressed on naive T cells, is downregulated on CD4 T cells of patients with IPF and that CD70, the sole ligand for CD27, is present on human pulmonary fibroblasts. We hypothesized that cognate engagements between lymphocyte CD27 and fibroblast CD70 could have functional consequences. Accordingly, a series of subsequent studies were conducted to examine the possible role of CD27-CD70 interactions in the regulation of fibrogenesis. Using IB, flow cytometry, RT-PCR, and kinomic assays, we found that fibroblast CD70 expression was inversely correlated with cell density and upregulated by TGF-β1 (transforming growth factor-β1). CD70 agonists, including T-cell-derived soluble CD27, markedly diminished fibroblast collagen and fibronectin synthesis, and these effects were potent enough to also inhibit profibrotic actions of TGF-β1 on ECM production in vitro and in two distinct ex vivo human skin models. CD70 activation was mediated by AKT (protein kinase B) and complex interconnected signaling pathways, and it was abated by prior CD70 knockdown. These results show that the CD70-CD27 axis modulates T-cell-fibroblast interactions and may be an important regulator of fibrosis and wound healing. Fibroblast CD70 could also be a novel target for specific mechanistically based antifibrosis treatments.

The Pathogenesis of Systemic Sclerosis: An Understanding Based on a Common Pathologic Cascade across Multiple Organs and Additional Organ-Specific Pathologies

Systemic sclerosis (SSc) is a multisystem autoimmune and vascular disease resulting in fibrosis of various organs with unknown etiology. Accumulating evidence suggests that a common pathologic cascade across multiple organs and additional organ-specific pathologies underpin SSc development. The common pathologic cascade starts with vascular injury due to autoimmune attacks and unknown environmental factors. After that, dysregulated angiogenesis and defective vasculogenesis promote vascular structural abnormalities, such as capillary loss and arteriolar stenosis, while aberrantly activated endothelial cells facilitate the infiltration of circulating immune cells into perivascular areas of various organs. Arteriolar stenosis directly causes pulmonary arterial hypertension, scleroderma renal crisis and digital ulcers. Chronic inflammation persistently activates interstitial fibroblasts, leading to the irreversible fibrosis of multiple organs. The common pathologic cascade interacts with a variety of modifying factors in each organ, such as keratinocytes and adipocytes in the skin, esophageal stratified squamous epithelia and myenteric nerve system in gastrointestinal tract, vasospasm of arterioles in the heart and kidney, and microaspiration of gastric content in the lung. To better understand SSc pathogenesis and develop new disease-modifying therapies, it is quite important to understand the complex pathogenesis of SSc from the two distinct perspectives, namely the common pathologic cascade and additional organ-specific pathologies.

Bi-directional communication: Conversations between fibroblasts and immune cells in systemic sclerosis

Systemic Sclerosis (SSc) is an autoimmune idiopathic connective tissue disease, characterized by aberrant fibro-proliferative and inflammatory responses, causing fibrosis of multiple organs. In recent years the interactions between innate and adaptive immune cells with resident fibroblasts have been uncovered. Cross-talk between immune and stromal cells mediates activation of stromal cells to myofibroblasts; key cells in the pathophysiology of fibrosis. These cells and their cytokines appear to mediate their effects in both a paracrine and autocrine fashion. This review examines the role of innate and adaptive immune cells in SSc, focusing on recent advances that have illuminated our understanding of ongoing bi-directional communication between immune and stromal cells. Finally, we appraise current and future therapies and how these may be useful in a disease that currently has no specific disease modifying treatment.

Predictors of progression in systemic sclerosis patients with interstitial lung disease

Systemic sclerosis (SSc) is a systemic autoimmune disease affecting multiple organ systems, including the lungs. Interstitial lung disease (ILD) is the leading cause of death in SSc.

There are no valid biomarkers to predict the occurrence of SSc-ILD, although auto-antibodies against anti-topoisomerase I and several inflammatory markers are candidate biomarkers that need further evaluation. Chest auscultation, presence of shortness of breath and pulmonary function testing are important diagnostic tools, but lack sensitivity to detect early ILD. Baseline screening with high-resolution computed tomography (HRCT) is therefore necessary to confirm an SSc-ILD diagnosis. Once diagnosed with SSc-ILD, patients' clinical courses are variable and difficult to predict, although certain patient characteristics and biomarkers are associated with disease progression. It is important to monitor patients with SSc-ILD for signs of disease progression, although there is no consensus about which diagnostic tools to use or how often monitoring should occur. In this article, we review methods used to define and predict disease progression in SSc-ILD.

There is no valid definition of SSc-ILD disease progression, but we suggest that either a decline in forced vital capacity (FVC) from baseline of ≥10%, or a decline in FVC of 5–9% in association with a decline in diffusing capacity of the lung for carbon monoxide of ≥15% represents progression. An increase in the radiographic extent of ILD on HRCT imaging would also signify progression. A time period of 1–2 years is generally used for this definition, but a decline over a longer time period may also reflect clinically relevant disease progression.

Lung function tests and chest imaging help predict who has SSc-associated ILD and whether it will progress. In the absence of standardised methods for doctors, we recommend a strategy that combines both lung function tests and chest imaging.http://bit.ly/2uK9ZD2

T-Cell Proapoptotic and Antifibrotic Activity Against Autologous Skin Fibroblasts in vitro Is Associated With IL-17A Axis Upregulation in Systemic Sclerosis

Background: Systemic sclerosis (SSc) T cells can induce apoptosis of autologous skin fibroblasts in vitro. Th17 cells have been reported to increase in SSc patients, and interleukin-17A (IL-17A) has a profibrotic function. We used a system based on T-cell-autologous fibroblast co-cultures to further investigate a possible role of IL-17A in SSc.

Methods: T cells from diffuse SSc patients were co-cultured with autologous skin fibroblasts. IL17A mRNA was assessed by real-time PCR in co-cultured and control T cells, while IL17RA, CXCL1, CCL2, CCL3, COL1A1, COL3A1, CTGF, TGFBR2, and SMAD3 mRNAs were assessed in co-cultured and control fibroblasts. In subset experiments, co-cultures and control cells were treated with either IL-17A or IL-17A plus anti-IL17 receptor monoclonal antibody (α-IL-17RA mAb). Chemokine and procollagen type I (PCI) production was further investigated at the protein level in cell culture supernatants by multiple suspension immunoassay and sandwich ELISA, respectively. Co-cultured and control fibroblasts were also stained with Annexin V and analyzed by flow cytometry.

Results: T cell–fibroblast co-cultures overexpressed IL17A and IL17RA. Furthermore, co-cultured fibroblasts upregulated IL-17A targets CXCL1, CCL2, and CCL3, while COL1A1, COL3A1, CTGF, and two key effectors of the TGF-β signaling, TGFBR2 and SMAD3, were found downregulated. Consistently, chemokine concentrations were increased in co-culture supernatants, while PCI levels were reduced, especially after stimulation with ectopic IL-17A. Finally, simultaneous α-IL-17RA mAb treatment restored PCI levels and reduced fibroblast apoptosis in IL-17A-stimulated co-cultures.

Conclusion: These data suggest that IL-17A upregulation might play a role in modulating T cell-mediated antifibrotic and proapoptotic effects in co-cultured autologous skin fibroblasts.

Treatment of Systemic Sclerosis-related Interstitial Lung Disease: A Review of Existing and Emerging Therapies

Although interstitial lung disease accounts for the majority of deaths of patients with systemic sclerosis, treatment options for this manifestation of the disease are limited. Few high-quality, randomized, controlled trials exist for systemic sclerosis-related interstitial lung disease, and historically, studies have favored the use of cyclophosphamide. However, the benefit of cyclophosphamide for this disease is tempered by its complex adverse event profile. More recent studies have demonstrated the effectiveness of mycophenolate for systemic sclerosis-related interstitial lung disease, including Scleroderma Lung Study II. This review highlights the findings of this study, which was the first randomized controlled trial to compare cyclophosphamide with mycophenolate for the treatment of systemic sclerosis-related interstitial lung disease. The results reported in this trial suggest that there is no difference in treatment efficacy between mycophenolate and cyclophosphamide; however, mycophenolate appears to be safer and more tolerable than cyclophosphamide. In light of the ongoing advances in our understanding of the pathogenic mechanisms underlying interstitial lung disease in systemic sclerosis, this review also summarizes novel treatment approaches, presenting clinical and preclinical evidence for rituximab, tocilizumab, pirfenidone, and nintedanib, as well as hematopoietic stem cell transplantation and lung transplantation. This review further explores how reaching a consensus on appropriate study end points, as well as trial enrichment criteria, is central to improving our ability to judiciously evaluate the safety and efficacy of emerging experimental therapies for systemic sclerosis-related interstitial lung disease.

Progranulin Overproduction Due to Fli-1 Deficiency Contributes to the Resistance of Dermal Fibroblasts to Tumor Necrosis Factor in Systemic Sclerosis

OBJECTIVE

Progranulin is a growth factor that is active in wound repair and is an antagonist of tumor necrosis factor (TNF) receptors, regulating fibroblast activation, angiogenesis, and inflammation. Because long-standing activation of gene programs related to wound healing is a hallmark of systemic sclerosis (SSc), we sought to investigate the role of progranulin in SSc.

METHODS

Progranulin expression levels in human and murine skin samples were determined by immunohistochemical analysis and quantitative reverse transcription-polymerase chain reaction. The role of progranulin in fibroblast activation was examined using a gene-silencing technique. Progranulin levels in serum obtained from 60 patients with SSc and 16 healthy control subjects were determined by enzyme-linked immunosorbent assay.

RESULTS

Progranulin expression was increased in SSc dermal fibroblasts compared with normal dermal fibroblasts, both in vivo and in vitro. Transcription factor Fli-1, a deficiency of which is involved in the activation of SSc dermal fibroblasts, served as a potent repressor of the progranulin gene, and Fli-1(+/-) mice and bleomycin-treated wild-type mice exhibited up-regulated expression of progranulin in dermal fibroblasts. SSc dermal fibroblasts were resistant to the antifibrotic effect of TNF, but this resistance was reversed by gene silencing of progranulin. Serum progranulin levels were elevated in patients with early diffuse cutaneous SSc (dcSSc), especially in those with inflammatory skin symptoms, and were positively correlated with the C-reactive protein level.

CONCLUSION

Progranulin overproduction due to Fli-1 deficiency may contribute to the constitutive activation of SSc dermal fibroblasts by antagonizing the antifibrotic effect of TNF. Progranulin may also be involved in the inflammatory process associated with progressive skin sclerosis in early dcSSc.

Vasculopathy in scleroderma

Systemic sclerosis (SSc) is a multisystem connective tissue disorder featured by vascular injury and fibrosis of the skin and various internal organs with autoimmune background. Although the pathogenesis of SSc still remains elusive, it is generally accepted that initial vascular injury due to autoimmunity and/or environmental factors causes structural and functional abnormalities of vasculature which eventually result in the constitutive activation of fibroblasts in various organs. Structural alterations consist of destructive vasculopathy (loss of small vessels) and proliferative obliterative vasculopathy (occlusion of arterioles and small arteries with fibro-proliferative change) caused by impaired compensatory vasculogenesis and angiogenesis. Impaired function of SSc vasculature includes the altered expression of cell adhesion molecules predominantly inducing Th2 and Th17 cell infiltration, endothelial dysfunction primarily due to the low availability of nitric oxide, the activated endothelial-to-mesenchymal transition leading to fibro-proliferative vascular change and tissue fibrosis, and the impaired coagulation/fibrinolysis system promoting the formation of intravascular fibrin deposits. Recent new insights into the therapeutic mechanisms of intravenous cyclophosphamide pulse and bosentan and the establishment of a new SSc animal model (Klf5 (+/-);Fli1 (+/-) mice) provide us useful clues to further understand the development of vascular alterations characteristic of SSc. This article overviewed the present understanding of the pathogenesis of SSc vasculopathy.

The role of the acquired immune response in systemic sclerosis

Profound alterations characterize the adaptive immune response in systemic sclerosis, and several layers of evidence support a prominent role exerted by immune cellular effectors and humoral mediators in the pathogenesis of this disease. These include (i) the presence of oligoclonal T cells in tissues undergoing fibrosis consistent with (auto)antigen-specific recruitment, (ii) the preferential expansion of polarized CD4+ and CD8+ T cells producing pro-fibrotic cytokines such as IL-4 and IL-13, (iii) the presence of increased number of cells producing mediators belonging to the IL-17 family, including IL-22, which may drive and participate in inflammatory pathways involving epithelial cells as well as fibroblasts, (iv) the deficient or redirected function of T regulatory cells favoring fibrosis, and (v) the enhanced expression of CD19 and CD21 on naïve B cells, and the upregulation of co-stimulatory molecules in mature B cells, which together with the increased levels of B cell activating factor (BAFF) underlie the propensity to an exaggerated humoral response possibly favoring fibrogenesis. Despite all the progress made in understanding the features of the aberrant immune response in scleroderma, it remains unclear whether the activation of immune effector pathways ultimately drives the disease pathogenesis or rather represents a defective attempt to limit or even reverse excessive extracellular matrix deposition and progressive vasculopathy, the main hallmarks of this disease.

B lymphocytes and B-cell activating factor promote collagen and profibrotic markers expression by dermal fibroblasts in systemic sclerosis

Introduction

B lymphocytes might play a pathogenic role in dermal fibrosis in systemic sclerosis (SSc). B-cell activating factor (BAFF), a key cytokine for B-cell activation, is increased in the serum and the skin of patients with SSc. However, the ability of B cells directly to stimulate dermal fibroblasts and the role of BAFF are not fully understood. We therefore investigated the involvement of B cells and BAFF in the expression of collagen and profibrotic markers by dermal fibroblasts.

Methods

Cocultures of blood B cells from healthy blood donors and normal or SSc dermal fibroblasts stimulated with anti-IgM and BAFF were performed. Alpha-SMA, TIMP1, MMP9, COL1A1, COL1A2, and COL3A1 mRNA expression were determined by quantitative RT-PCR. Soluble collagen, BAFF, IL-6, IL-1β, TGF-β1, and CCL2 protein secretion were assessed.

Results

Coculture of blood B cells and dermal fibroblasts isolated from SSc patients induced IL-6, TGF-β1, CCL2, and collagen secretion, as well as Alpha-SMA, TIMP1, and MMP9 expression in dermal fibroblasts. Transwell assays demonstrated that this induction was dependent on cell-cell contact. Addition of anti-IgM and BAFF to the coculture increased IL-6, CCL2, TGF-β1, and collagen secretion. B cell- and BAFF-induced collagen secretion was highly reduced by anti-TGF-β1 antibodies.

Conclusions

Our results showed for the first time a direct role of B cells on the production of collagen by dermal fibroblasts, which is further enhanced by BAFF. Thus, these results demonstrate a new pathogenic role of B cells and BAFF in fibrosis and systemic sclerosis.

Th17 cells favor inflammatory responses while inhibiting type I collagen deposition by dermal fibroblasts: differential effects in healthy and systemic sclerosis fibroblasts

INTRODUCTION

T helper (Th)-17 cells are increased in systemic sclerosis (SSc). We therefore assessed whether Th17 cells could modulate the inflammatory and fibrotic responses in dermal fibroblasts from healthy donors (HD) and SSc individuals.

METHODS

Fibroblasts were obtained from 14 SSc and 8 HD skin biopsies. Th17 clones were generated from healthy peripheral blood upon enrichment of CC chemokine receptor (CCR)-4/CCR6/CD161 expressing cells. Their cytokine production was assessed by flow cytometry and multiplex beads immunoassay. Fibroblast production of monocyte chemoattractant protein (MCP)-1, interleukin (IL)-8, matrix metalloproteinase (MMP)-1, tissue inhibitor of metalloproteinase (TIMP)-1, MMP-2 and type-I collagen was quantified by enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA), and changes in their transcription levels assessed by real-time PCR. Intracellular signals were dissected by western blot and the use of pharmacological inhibitors. IL-17A, tumor necrosis factor (TNF) and interferon-gamma (IFN-γ) blocking reagents were used to assess the specificity of the observed effects.

RESULTS

IL-17A increased MCP-1, IL-8 and MMP-1 production in a dose-dependent manner while having no effect on type I collagen in HD and SSc fibroblasts both at protein and mRNA levels. Nuclear factor-kappa B (NF-κB) and p38 were preferentially involved in the induction of MCP-1 and IL-8, while MMP-1 was most dependent on c-Jun N-terminal kinase (JNK). Supernatants of activated Th17 clones largely enhanced MCP-1, IL-8 and MMP-1 while strongly inhibiting collagen production. Of note, the production of MCP-1 and IL-8 was higher, while collagen inhibition was lower in SSc compared to HD fibroblasts. The Th17 clone supernatant effects were mostly dependent on additive/synergistic activities between IL-17A, TNF and in part IFN-γ. Importantly, the inhibition of type I collagen production induced by the Th17 clone supernatants was completely abrogated by blockade of IL-17A, TNF and IFN-γ mostly in SSc fibroblasts, revealing an intrinsic resistance to inhibitory signals in SSc.

CONCLUSIONS

Our findings demonstrate that in vitro Th17 cells elicit pro-inflammatory responses while restraining collagen production. Thus, the increased Th17 cell number observed in SSc may impact on the inflammatory component of the disease simultaneously potentially providing a protective role against fibrosis.

Fibrosis and immune dysregulation in systemic sclerosis

Autoimmune and inflammatory phenomena are characteristically present in systemic sclerosis (SSc) and impact on dysregulated fibroblast extracellular matrix deposition, hallmark of the disease in conjunction with fibroproliferative vasculopathy. Oligoclonal T helper 2-like cells are present in the skin and peripheral blood in early diffuse disease. Type 2 cytokines synergize with profibrotic cytokines including transforming growth factor beta, favoring collagen deposition and metalloproteinase inhibition by fibroblasts. Furthermore, chemokine with pro-fibrotic and pro-angiogenic properties are preferentially produced by fibroblasts under the influence of Th2-like cells. The profibrotic monocyte chemotactic protein 1 is also produced by fibroblasts, partially in response to Toll-like receptor 4 (TLR4) recognition, when autoantibodies (autoAb) bind to fibroblast surface. In addition, immune-complex formed by autoAb and ubiquitous antigens including topoisomerase-1 favor the production of interferon-alpha (IFN-α) possibly by interacting with intravesicular TLRs. Consistent with this findings, unbiased gene screening has revealed that SSc peripheral blood cells express genes induced by IFN-α, a characteristic shared with systemic lupus erythematosus and other autoimmune disorders. These findings highlight the complex relationship between adaptive and acquired immune responses, which may participate to the pathogenesis of SSc in manners until now unsuspected, which may help in identifying novel therapeutic targets.

Interstitial lung disease in systemic sclerosis

Interstitial lung disease (ILD) is a common manifestation of systemic sclerosis (SSc) and mainly encountered in patients with diffuse disease and/or anti-topoisomerase 1 antibodies. ILD develops in up to 75% of patients with SSc overall. However, SSc-ILD evolves to end-stage respiratory insufficiency in only a few patients. Initial pulmonary function tests (PFT) with measurement of carbon monoxide diffusing capacity, together with high-resolution computed tomography, allows for early diagnosis of SSc-ILD, before the occurrence of dyspnea. Unlike idiopathic ILD, SSc-ILD corresponds to non-specific interstitial pneumonia in most cases, whereas usual interstitial pneumonia is less frequently encountered. Therefore, the prognosis of SSc-ILD is better than that for idiopathic ILD. Nevertheless, ILD represents one of the two main causes of death in SSc patients. To detect SSc-ILD early, PFT must be repeated regularly, every 6 months to 1 year, depending on disease worsening. Conversely, broncho-alveolar lavage is not needed to evaluate disease activity in SSc-ILD but may be of help in diagnosing opportunistic infection. The treatment of SSc-ILD is not well established. Cyclophosphamide, which has been used for 20 years, has recently been evaluated in two prospective randomized studies that failed to demonstrate a major benefit for lung function. Open studies reported mycophenolate mofetil, azathioprine and rituximab as alternatives to cyclophosphamide. On failure of immunosuppressive agent treatment, lung transplantation can be proposed in the absence of other major organ involvement or severe gastro-esophageal reflux.

[Cytokines and T cell differentiation in systemic sclerosis]

The physiopathology of systemic sclerosis remains unclear within a complex interaction between vasculopathy, perivascular inflammatory infiltrate, extensive tissue fibrosis and auto-immune manifestations. Chronology between vascular disease and adjacent inflammatory cell infiltration is still not yet clarified. There is growing evidence that T cell activation and its cytokine expression play a key role in vascular impairment occurrence and collagen dysregulation. Nevertheless, cytokine descriptions are mainly limited to blood and tissue measurement and the T cells differentiation analysis restricted to the Th1/Th2 balance. The purpose of this review is to establish an exhaustive cartography of cytokines involved in T cell differentiation, regarding the recent advance in T lymphocyte differentiation, including Th9, Th17, Th22 and regulatory T cells (Treg) pathways. This review will focus on Th17, Th22 and Treg differentiation, corresponding to the equilibrium between inflammation and tolerance. Finally, regarding published results in systemic sclerosis, T cells participation appears to be more a Th1/Th2 co-expression than an exclusive Th1 or Th2 polarization. Also, a possible Th22/Treg imbalance is suggested, leading to a Th22 overexpression and likely to tissue inflammation genesis.

Fibrosis in systemic sclerosis

This article reviews current understanding of the pathophysiology of fibrosis in systemic sclerosis. It highlights recent discoveries, insights, and emerging research, and potential opportunities for the development of targeted antifibrotic therapies.

The immunobiology of systemic sclerosis

OBJECTIVES

Systemic sclerosis (SSc) is a chronic connective tissue disease characterized by vascular damage, autoimmunity, and excessive collagen deposition. Despite advances in disease-specific treatment of other rheumatologic diseases, disease-targeted treatment in SSc continues to be elusive. In this review, our goal was to place the contemporary immunobiology of SSc in the perspective of clinical medicine.

METHODS

We performed a PubMed search for the period from 1989 to 2007, using the keyword, "systemic sclerosis," resulting in a total of 9099 publications, including 1252 reviews. Articles were then selected based on their discussion of recent advances in the elusive pathogenesis of SSc. A final total of 259 articles were chosen for the review.

RESULTS

The SSc hallmarks of vascular damage, immunologic activation, and collagen deposition can be traced to 4 major factors: T-cells, fibroblasts, B-cells, and cytokines/chemokines. T-cells are a major component of the infiltrate in skin and lung, exhibiting increased expression of activation markers and showing signs of antigen-driven expansion. Preliminary data indicate that induction of oral tolerance with collagen, a target of SSc T-cell responses, is associated with clinical benefits. Although this suggests that T-cells participate in the pathogenesis of SSc, their precise role and antigen specificity largely remain to be elucidated. Defective numbers and functions of certain T-cell subsets, such as natural killer and gammadelta T-cells, may be involved in the failure to maintain tolerance. Other data suggest that gammadelta T-cells may themselves be effector cells in endothelial cell cytotoxicity. There are several lines of evidence for a pathogenic role of B-cells in SSc, in particular, through the production of autoantibodies. Antibody-dependent cell-mediated cytotoxicity is a primary pathogenic event in an animal model of SSc and is likely to be involved in human SSc. Nonetheless, there is as yet no convincing evidence for the pathogenicity of SSc-specific antibodies. SSc fibroblasts exhibit a specific phenotype characterized not only by excessive collagen production but also by increased responsiveness to and production of cytokines and chemokines. This phenotype is induced by a complex network of cytokines and chemokines but appears to be maintained in the absence of exogenous stimuli via the autocrine production of some of these factors by SSc fibroblasts themselves, particularly transforming growth factor, platelet-derived growth factor, monocyte chemoattractant protein 1, and interleukin-1.

CONCLUSIONS

Significant variations in laboratory data among patients suggest that the pathology reflects a heterogeneous disease. Nonetheless, the possibility of achieving clinical benefits by inducing oral tolerance highlights the importance of characterizing SSc T-cell antigens. It is hoped that the identification of some of the key players in the induction and maintenance of the SSc fibroblast phenotype may yield new disease-targeted treatment regimens for patients with SSc.

[Interstitial lung disease in systemic sclerosis]

INTRODUCTION

Interstitial lung diseases (ILD) in systemic sclerosis (SSc) are mainly encountered in patients with diffuse disease although they may occur less frequently in patients with limited cutaneous disease.

BACKGROUND

In SSc early detection of ILD should be achieved by high resolution computed tomography and pulmonary function tests, including measurement of DLCO. In total up to 75% of patients with SSc develop ILD but it is progressive in only a minority of patients. Unlike idiopathic ILD, SSc associated ILD corresponds to non-specific interstitial pneumonia rather than usual interstitial pneumonia in the majority of cases. This explains the better prognosis of SSc associated ILD compared with idiopathic ILD. Nevertheless ILD represents one of the two main causes of death in SSc.

VIEWPOINT

The treatment of SSc associated ILD is not well established. Anti-fibrosing treatments have failed to demonstrate benefit and cyclophosphamide, which has been used for about 15 years in the treatment of this condition, has recently been evaluated in two prospective randomised studies which showed a significant but modest effect on respiratory function.

CONCLUSION

A subgroup of patients with rapidly progressive ILD might benefit from pulsed intravenous cyclophosphamide combined with prednisone 15 mg daily, but this remains to be confirmed.

Presence of CD4+CD8+ double-positive T cells with very high interleukin-4 production potential in lesional skin of patients with systemic sclerosis

OBJECTIVE

Fibrotic skin changes in systemic sclerosis (SSc) are preceded by the appearance of an inflammatory infiltrate rich in T cells. Since no direct comparison with T cells in normal skin has been performed previously, this study was undertaken to functionally characterize T cells in the skin of patients with early active SSc and in normal skin.

METHODS

We characterized coreceptor expression, T cell receptor (TCR) usage, cytokine production, and helper and cytolytic activity of T cell lines and clones established from skin biopsy specimens from 6 SSc patients and 4 healthy individuals. Immunofluorescence analysis of skin biopsy and peripheral blood samples was performed to confirm the presence of specific subsets in vivo.

RESULTS

A distinct subset expressing both CD4 and CD8alpha/beta coreceptors at high levels (double-positive [DP]) was present in T cell lines from SSc and normal skin. DP T cells actively transcribed both accessory molecules, exerted clonally distributed cytolytic and helper activity, and expressed TCR clonotypes distinct from those in CD4+ or CD8+ single-positive (SP) T cells. In SSc skin, DP T cells produced very high levels of interleukin-4 (IL-4) compared with CD4+ SP T cells. Furthermore, DP T cells were directly identified in SSc skin, thus providing evidence that they are a distinct subset in vivo.

CONCLUSION

The present findings show that T cells with the unusual CD4+CD8+ DP phenotype are present in the skin. Their very high level of IL-4 production in early active SSc may contribute to enhanced extracellular matrix deposition by fibroblasts.

Human T cells stimulate fibroblast-mediated degradation of extracellular matrix in vitro

Several chronic diseases are characterized by inflammation, T cell recruitment and tissue remodelling. We hypothesized that activated T cells may stimulate remodelling of extracellular matrix (ECM) in vitro. Total T cells (CD3+) as well as CD4+ and CD8+ subsets were isolated from peripheral blood and stimulated, after which conditioned media (CM) were obtained. CM was added to human lung fibroblasts in three-dimensional collagen gels and the area of gels was measured daily. Hydroxyproline was determined as a measure of collagen degradation in the gels. Matrix metalloproteinase (MMP) activity in the culture media was analysed by gelatine zymography. Cytokine secretion of stimulated CD4+ and CD8+ T cells was analysed. CD3+ CM augmented collagen gel contraction in a time- and dose-dependent manner (P < 0.0001). CD4+ T cell CM was more potent than CD8+ T cell CM (P < 0.001). CD3+ CM and CD4+ T cell CM, but not CD8+ T cell CM, stimulated fibroblast-mediated collagen degradation and MMP-9 activity. A broad-spectrum MMP-inhibitor added to the culture system inhibited both gel contraction and MMP activity. Activated CD4+ T cells secreted significantly more tumour necrosis factor (TNF) and interleukin (IL)-6 compared to CD8+ T cells. CD3+ CM from patients with chronic obstructive pulmonary disease stimulated fibroblast-mediated collagen gel contraction to the same magnitude as CD3+ CM from healthy controls. In conclusion, activated CD4+ T cells can stimulate fibroblast-mediated degradation of ECM in vitro. This could be a mechanism by which activated T cells stimulate degradation of lung tissue leading to pulmonary emphysema.

Complex regulation of pulmonary inflammation and fibrosis by CCL18

Elevated pulmonary levels of CCL18 have been associated with influx of T lymphocytes, collagen accumulation, and a decline in lung function in pulmonary fibrosis patients. We previously reported that overexpression of CCL18 in mouse lungs triggers selective infiltration of T lymphocytes and moderate lymphocyte-dependent collagen accumulation. We hypothesized that in combination with bleomycin injury, overexpression of CCL18 will worsen the severity of lung inflammation and fibrosis. Mice were infected with a replication-deficient adenovirus encoding CCL18 and then instilled with bleomycin; control mice were challenged with either CCL18 overexpression or bleomycin. Additive effects of CCL18 overexpression and bleomycin injury were observed on pulmonary inflammation, particularly on T-cell infiltration, and increased levels of tumor necrosis factor-alpha, interferon-gamma, matrix metalloproteinase (MMP)-2, and MMP-9. Despite the additive effect on inflammation, CCL18 overexpression unexpectedly attenuated the bleomycin-induced collagen accumulation. Pulmonary levels of active transforming growth factor-beta1 mirrored the changes in collagen levels. Depletion of T cells with antilymphocyte serum or pharmacological inhibition of MMPs with GM6001 abrogated accumulation of collagen and increases in the levels of tumor necrosis factor-alpha, interferon-gamma, and active transforming growth factor-beta1. Thus, CCL18-stimulated T-lymphocytic infiltration is by itself mildly profibrotic to a healthy lung, whereas it partially protects against lung fibrosis in an inflammatory profibrotic pulmonary milieu.

Pamidronate infusion in patients with systemic sclerosis results in changes in blood mononuclear cell cytokine profiles

A single infusion of pamidronate was given to patients with systemic sclerosis (scleroderma, SSc) to assess effects on cytokine production by peripheral blood mononuclear cells (PBMC) and lymphocyte subsets. Eighteen patients with SSc received a single intravenous dose of 60 mg of pamidronate and were followed for 6 months. Assessment of cytokine production [interferon (IFN)-gamma, interleukin (IL)-10, transforming growth factor (TGF)-beta1, tumour necrosis factor (TNF)-alpha and IL-4] by PBMC and lymphocyte subsets by flow cytometry was carried out before and after the pamidronate infusion. Unstimulated PBMC produced increased amounts of IFN-gamma and TNF-alpha and reduced levels of TGF-beta1 for up to 24 weeks after the infusion. gammadelta T cells from patients with SSc were activated in vitro and produced increased IFN-gamma. The effects of pamidronate on modulation of cytokine profiles in patients with SSc may merit future study.

Polarized subsets of human T-helper cells induce distinct patterns of chemokine production by normal and systemic sclerosis dermal fibroblasts

The role of fibroblasts in inflammatory processes and their cross-talk with T cells is increasingly being recognized. Our aim was to explore the capacity of dermal fibroblasts to produce inflammatory chemokines potentially involved in fibrosis occurring in response to contact with polarized human T cells. Our findings indicate that the program of chemokine production by fibroblasts is differentially regulated depending on the T-helper (Th) cell subset used to activate them. Thus, Th1 and Th2 cells preferentially induced production of IFN-γ inducible protein (IP)-10 and IL-8, respectively, whereas monocyte chemoattractant protein (MCP)-1 was equally induced by both subsets at mRNA and protein levels. Neutralization experiments indicated that membrane-associated tumour necrosis factor-α and IL-1 played a major role in the induction of IL-8 and MCP-1 by Th1 and Th2 cells, whereas membrane-associated IFN-γ (present only in Th1 cells) was responsible, at least in part, for the lower IL-8 and higher IP-10 production induced by Th1 cells. The contributions of tumour necrosis factor-α, IL-1 and IFN-α were confirmed when fibroblasts were cultured separated in a semipermeable membrane from living T cells activated by CD3 cross-linking. We observed further differences when we explored signal transduction pathway usage in fibroblasts. Pharmacological inhibition of c-Jun N-terminal kinase and nuclear factor-κB resulted in inhibition of IL-8 mRNA transcription induced by Th1 cells but not that by Th2 cells, whereas inhibition of MEK/ERK (mitogen-activated protein kinase of extracellular signal-regulated kinase/extracellular signal-regulated kinase) and nuclear factor-κB resulted in inhibition of MCP-1 mRNA induced by Th2 but not by Th1 cells. Finally, no distinct differences in chemokine production were observed when the responses to T cell contact or to prototypic Th1 and Th2 cytokines were examined in systemic sclerosis versus normal fibroblasts. These findings indicate that fibroblasts have the potential to participate in shaping the inflammatory response through the activation of flexible programs of chemokine production that depend on the Th subset eliciting their response.

Update on pathophysiology of scleroderma with special reference to immunoinflammatory events

Scleroderma or systemic sclerosis (SSc) is a complex disease in which the vasculopathy and the activation of the immune system with production of inflammatory mediators lead to dysregulated fibroblast activation. The resulting excessive deposition of collagens and other extracellular matrix proteins ends in fibrosis and organ dysfunction. The cause is unknown, but environmental factors are thought to play a role by triggering abnormal responses in genetically susceptible hosts. The recent past has witnessed important advances in the definition of mechanisms that underlie the persistent activation in fibroblasts of genes involved in uncontrolled fibrosis, a hallmark of SSc. These include the preferential production of type 2 T cell cytokines in target organs, the presence of autoantibodies with fibroblast-activating capacities, the production of vasoconstrictive mediators that impact on fibroblast biosynthetic properties, the transforming growth factor-beta-related metabolic signature, and the presence of altered signaling pathways in fibroblasts. Furthermore, while no animal models recapitulate all the features of SSc, they have been instrumental for assessing the relevance of specific processes to the development of fibrosis. More importantly, some of the research findings are leading to therapies that target altered processes with the potential of changing the prognosis of some dismal aspects of the disease.

Pneumopathie infiltrante diffuse de la sclérodermie systémique

Interstitial lung diseases (ILD) associated with systemic sclerosis (SSc) are mainly encountered in patients with diffuse disease, although they may also be seen in patients with limited cutaneous SSc. ILD screening must be performed regularly, with high-resolution computed tomography and pulmonary function tests (TLCO). Up to 75% of patients with diffuse SSc develop a form of ILD. ILD remains stable in most patients and does not worsen. The nonspecific nature of SSc-associated ILD makes it different from idiopathic ILD and helps to explain its better prognosis. Nonetheless, ILD is one of the two leading causes of death in SSc patients. Treatment of SSc-associated ILD is not yet well codified. Antifibrotic treatments have not proved beneficial, and the efficacy of cyclophosphamide, which has been used to treat this condition for 15 years, has been shown to be very limited against SSc-associated ILD. A subgroup of patients with rapidly progressive ILD might benefit from intravenous cyclophosphamide pulses in association with 15 mg/d prednisone.

Physiopathologie de la sclérodermie systémique: état des lieux sur une affection aux multiples facettes

Systemic sclerosis is a rare disease characterized by vascular hyperreactivity and collagen deposition. Endothelial cell, fibroblast and lymphocyte abnormalities have been reported in systemic sclerosis. Fibroblast dysfunction is characterized by uncontrolled activation of the transforming growth factor-beta (TGF-beta) pathway and excess synthesis of both connective tissue growth factor (CTGF) and free radicals. These promote the accumulation of extracellular matrix. Endothelial cells produce excess quantities of endothelin 1 and inducible NO synthase. They also undergo early apoptosis. Oxidative stress appears to play a major role in disease progression. Increased levels of interleukin 4, a profibrotic cytokine, have been detected in plasma and skin of systemic sclerosis patients. Autoantibodies are detectable in the serum of almost all systemic sclerosis patients. Some are directed against well-identified ubiquitous nuclear proteins and have no demonstrated pathogenic role. Other autoantibodies bind to endothelial cells or fibroblasts and may have a pathogenic role.

Thalidomide attenuates the development of fibrosis during post-infarction myocardial remodelling in rats

BACKGROUND

Inflammation plays a pathogenic role in the development of heart failure (HF). The aim of this study was to examine the effect of treatment with the immunomodulating drug thalidomide in a rat model for post-myocardial infarction (MI) HF.

METHODS

Rats were subjected to MI by left coronary artery ligation or sham-operated. Seven days after surgical intervention rats were randomised to treatment with thalidomide or vehicle for 8 weeks.

RESULTS

Our main findings were: (i) thalidomide treatment did not affect cardiac function or the hypertrophic response, as determined by haemodynamic measurements and heart chamber weights, respectively. (ii) HF rats treated with thalidomide had a minor reduction in septum and relative wall thickness (p<0.05), indicating an anti-remodelling effect. (iii) Thalidomide appeared to have immunostimulatory effects on the myocardium as evident by increased MIP-1alpha gene expression (p<0.05). (iv) Treating HF rats with thalidomide reduced myocardial collagen content, as assessed by markedly decreased levels of hydroxyproline ( approximately 40% reduction; p<0.05), accompanied by lower TGF-beta(1) gene expression (p<0.05).

CONCLUSION

Although thalidomide had no effect on cardiac function, our results suggest that intervention with thalidomide may have beneficial effects in post-MI HF by attenuating collagen accumulation and development of myocardial fibrosis.

Proteasome blockade exerts an antifibrotic activity by coordinately down-regulating type I collagen and tissue inhibitor of metalloproteinase-1 and up-regulating metalloproteinase-1 production in human dermal fibroblasts

Tissue fibrosis results when dysregulation of extracellular matrix (ECM) turnover favors deposition of collagen and other ECM proteins over degradation. Fibrosis may then lead to organ dysfunction and pathology as observed in systemic sclerosis (SSc). In the present study, we investigated the antifibrotic properties of proteasome blockade. A dose- and time-dependent reduction in type-I collagen and tissue inhibitor of metalloproteinase-1 (TIMP-1) production was observed in normal fibroblasts exposed to proteasome inhibitors (PI). In the same culture conditions, metalloproteinase-1 (MMP-1) protein and the collagenolytic activity on type I collagen was increased. The steady-state mRNA levels of COL1A1, TIMP-1, and MMP-1 paralleled protein levels. These effects were dominant over the profibrotic properties of TGF-beta and were observed with fibroblasts generated from normal and SSc skin. PI decreased type I collagen mRNA levels with kinetics similar to those observed with DRB, a specific RNA polymerase II inhibitor, thus indicating transcriptional inhibition. Of interest, PI induced c-Jun phosphorylation and c-Jun nuclear accumulation. The specific N-terminal Jun-kinase inhibitor SP-600125 selectively abrogated c-Jun phosphorylation and, in a dose-dependent fashion, the up-regulated synthesis of MMP-1 induced by PI. Finally, PI did not affect fibroblast viability. Thus, the coordinated down-regulation of collagen and TIMP-1 and up-regulation of MMP-1 renders proteasome blockade an attractive strategy for treating conditions as SSc, characterized by excessive fibrosis.

Differential effects of the immunosuppressant FK-506 on human ?2(I) collagen gene expression and transforming growth factor ? signaling in normal and scleroderma fibroblasts

OBJECTIVE

To investigate the effects of FK-506 on the expression of the human alpha2(I) collagen gene and transforming growth factor beta (TGFbeta) signaling in normal and scleroderma fibroblasts.

METHODS

The expression levels of type I procollagen protein and alpha2(I) collagen messenger RNA (mRNA) were analyzed by immunoblotting and Northern blotting, respectively. The promoter activities of alpha2(I) collagen gene and 3TP-Lux were determined by transient transfection assay. Interaction between TGFbeta receptor type I and FK-506 binding protein 12 (FKBP12) was evaluated by immunoprecipitation.

RESULTS

FK-506 did not affect the basal expression of type I procollagen protein or alpha2(I) collagen mRNA, but it significantly reduced the TGFbeta1-induced expression of type I procollagen protein and alpha2(I) collagen mRNA in normal fibroblasts. The effect of FK-506 was regulated posttranscriptionally, but not transcriptionally. In scleroderma fibroblasts, FK-506 significantly reduced the expression of type I procollagen protein and alpha2(I) collagen mRNA through posttranscriptional regulation, but not transcriptional regulation. FK-506 increased the basal activity of the 3TP-Lux promoter, but it did not affect the TGFbeta1-induced promoter activity in normal fibroblasts. In contrast, FK-506 did not affect the basal or the TGFbeta1-induced 3TP-Lux promoter activity in scleroderma fibroblasts. Furthermore, FKBP12, which protects TGFbeta receptor type I from ligand-independent activation by TGFbeta receptor type II, constitutively dissociated from TGFbeta receptor type I in scleroderma fibroblasts.

CONCLUSION

FK-506 inhibits alpha2(I) collagen gene expression by reducing the stability of mRNA without exhibiting its activation effect on TGFbeta signaling in scleroderma fibroblasts.

Systemic sclerosis Th2 cells inhibit collagen production by dermal fibroblasts via membrane-associated tumor necrosis factor alpha

OBJECTIVE

In systemic sclerosis (SSc; scleroderma), T cells infiltrate organs undergoing fibrotic changes and may participate in dysregulated production of collagen by fibroblasts. The objective of this study was to functionally characterize T cells infiltrating skin lesions in early SSc and investigate their capacity to affect production of type I collagen and interstitial collagenase (matrix metalloproteinase 1 [MMP-1]) by dermal fibroblasts.

METHODS

Four-color cytometric analysis was used to characterize subset distribution and production of interferon-gamma (IFN gamma) and interleukin-4 (IL-4) in T cell lines generated from the skin of patients with SSc. T cell clones were generated, and their capacity to modulate collagen and MMP-1 production by fibroblasts derived from patients with SSc and from normal individuals was assessed. Neutralizing reagents were used to identify T cell mediators involved in fibroblast modulation.

RESULTS

The skin of individuals with early-stage SSc contained T cells preferentially producing high levels of IL-4. Cloned CD4+ Th2-like cells inhibited collagen production by normal fibroblasts. Th2 cell-dependent inhibition was, at least in part, contact-dependent, was essentially mediated by tumor necrosis factor alpha (TNF alpha), and was dominant over the enhancement induced by profibrotic IL-4 and transforming growth factor beta cytokines. The simultaneous induction of MMP-1 production confirmed the specificity of these observations. To be inhibitory, Th2 cells required activation by CD3 ligation. Th2 cells were less potent than were Th1 cells in inhibiting collagen production by normal fibroblasts via cell-to-cell interaction, and SSc fibroblasts were resistant to inhibition.

CONCLUSION

These findings indicate that, despite their production of IL-4, Th2 cells reduce type I collagen synthesis by dermal fibroblasts because of the dominant effect of TNF alpha, and suggest that strategies based on TNF alpha blockade aimed at controlling fibrosis in SSc may be unwise.

New insights into the pathogenesis of systemic sclerosis

Systemic sclerosis (SSc) is a connective tissue disorder characterized by vascular abnormalities and excessive collagen synthesis. Extracellular matrix overproduction by fibroblasts results from abnormal interactions among endothelial cells, mononuclear cells (lymphocytes and monocytes) and fibroblasts, in a setting of vascular hyperreactivity and tissue hypoxia. Many autoantibodies have been identified in the sera of SSc patients; some of them are specific to the disease, such as anti-centromere antibodies in limited SSc, anti-topoisomerase 1 and anti-RNA polymerase I/III antibodies in diffuse SSc. Their pathogenetic role(s) remains uncertain. However, genetic, environmental and possibly alloreactive factors might also contribute to disease susceptibility.

Topical noncorticosteroid immunomodulation in the treatment of atopic dermatitis

At present, the first-line drugs for treating atopic dermatitis are topical corticosteroids. They are effective when used short-term; however, long-term use of the corticosteroids is associated with suppressive effects on the connective tissue, seen as skin atrophy or resistance to therapy. Currently, two topical noncorticosteroid immunomodulators tacrolimus (FK506) and pimecrolimus (SDZ ASM 981) are under development, or already on the market in some countries for atopic dermatitis. These two compounds show structural similarity. In T lymphocytes they bind to the same cellular receptor, the FK-binding protein (FKBP) or macrophilin-12. Tacrolimus shows a 3-fold greater affinity to FKBP compared with pimecrolimus. The tacrolimus/ pimecrolimus-FKBP complex further binds to calcineurin, an enzyme vital for the early activation of T cells. The consequence of calcineurin binding is a lack of activation of both T helper cell types 1 and 2. Further effects of these compounds have been suggested on other inflammatory cells, such as Langerhans cells and mast cells/basophils. In contrast to corticosteroids, no suppressive effects on connective tissue cells have been observed. Taken together, treatment of inflammation results in healing of the barrier function of the skin. This again results in reduced bioavailability of the drug, as compared with systemic use. Placebo-controlled studies have shown the efficacy of both tacrolimus (at 0.03 and 0.1%) and pimecrolimus (at 0.6 and 1%). The main adverse event in these studies has been a burning sensation and increased pruritus at the site of application. Typically, these adverse events are observed only during the first days of treatment. Long-term safety studies, of up to one year, have not revealed any new adverse events. So far, long-term use of topical noncorticosteroid compounds has not been associated with signs of immune deficiency. Although there is currently no evidence for clinically relevant, prolonged adverse effects, some of these, such as an increased risk of photocarcinogenesis, need to be monitored. There is evidence from tacrolimus studies that monotherapy results in better long-term results when compared with combination therapy with corticosteroids. Tacrolimus and pimecrolimus could replace topical corticosteroids as the first-line treatment of atopic dermatitis.

Autoantibodies to fibroblasts induce a proadhesive and proinflammatory fibroblast phenotype in patients with systemic sclerosis

OBJECTIVE

Fibroblasts play a major role in the development of systemic sclerosis (SSc), and the occurrence of serum autoantibodies reacting with fibroblast plasma membrane antigens in SSc has been reported. This study was undertaken to investigate whether IgG from SSc sera that react with human fibroblasts modulates the fibroblasts' function.

METHODS

Sera from 69 patients with SSc (28 with limited cutaneous SSc [lcSSc] and 41 with diffuse cutaneous SSc [dcSSc]), 30 patients with sarcoidosis, and 50 matched healthy controls were examined. We evaluated antibody binding to human skin and lung fibroblasts by cell-based enzyme-linked immunosorbent assay (ELISA), indirect immunofluorescence, and flow cytometry. We further investigated the ability of purified IgG to modulate 1) intercellular adhesion molecule 1 (ICAM-1) expression, 2) U937 cell adhesion to fibroblasts, and 3) fibroblast steady-state messenger RNA (mRNA) levels of interleukin-1alpha (IL-1alpha), IL-beta, and IL-6, and IL-6 protein production.

RESULTS

Of 69 SSc sera tested by cell-based ELISA, 58% bound to normal skin and lung fibroblasts. The prevalence of binding was significantly higher in dcSSc than in lcSSc (P < 0.05). Only IgG from SSc sera that were positive for antifibroblast antibody (AFA) induced a dose-dependent up-regulation of ICAM-1 expression and IL-6 production, enhancement of U937 cell adhesion, and increased levels of IL-1alpha, IL-1beta, and IL-6 mRNA in fibroblasts. Up-regulation of ICAM-1 mediated by AFA IgG was inhibited by the addition of IL-1 receptor antagonist, indicating an autocrine activation loop.

CONCLUSION

Our findings confirm the presence of AFAs in SSc sera and demonstrate, for the first time, that autoantibodies reacting with fibroblast surface molecules act as an extrinsic stimulus inducing fibroblast activation in vitro.

Overexpression of monocyte chemoattractant protein 1 in systemic sclerosis: role of platelet-derived growth factor and effects on monocyte chemotaxis and collagen synthesis

OBJECTIVE

In addition to its chemotactic properties, recent evidence suggests that monocyte chemoattractant protein 1 (MCP-1) might participate in the fibrotic process by inducing the secretion of extracellular matrix (ECM) components. Since the factors that initiate the accumulation of inflammatory infiltrates and ECM deposits in systemic sclerosis (SSc) skin lesions are still unknown, this study was undertaken to examine the role of MCP-1 in SSc.

METHODS

In situ hybridization and immunohistochemistry studies for MCP-1 were performed on skin biopsy specimens from patients with SSc and healthy controls. To identify possible stimulators of MCP-1 overexpression in SSc lesions, cultured dermal fibroblasts were incubated with recombinant platelet-derived growth factor (PDGF) and analyzed by real-time polymerase chain reaction (PCR) and enzyme-linked immunosorbent assay. The chemotactic effects of SSc fibroblasts were examined using a modified Boyden chamber assay. To analyze the fibrotic potential of MCP-1, cultured dermal fibroblasts were incubated with recombinant MCP-1, and type I procollagen was measured by radioimmunoassay and real-time PCR.

RESULTS

MCP-1 was expressed by fibroblasts, keratinocytes, and perivascular infiltrates throughout the skin, in involved as well as uninvolved skin areas, from 10 of 11 SSc patients, whereas no expression of MCP-1 was found in healthy controls. Stimulation with PDGF resulted in a significant increase in MCP-1 messenger RNA and protein, with differences between healthy control fibroblasts and fibroblasts from SSc patients. The chemotactic activity for peripheral blood mononuclear cells of SSc fibroblast supernatants increased in a time-dependent manner. Antibodies blocking MCP-1 decreased the chemotactic activity of SSc fibroblasts by a mean +/- SD of 37 +/- 12%. Despite an increase in type I collagen levels over time, no effect of recombinant MCP-1 on the synthesis of type I collagen was observed.

CONCLUSION

These data indicate that MCP-1 might contribute to the initiation of inflammatory infiltrates in SSc. Possible stimuli of MCP-1 in dermal SSc lesions include PDGF, which is known to be expressed in SSc. In contrast to previous findings in fibrotic lung diseases, no effect of MCP-1 on collagen synthesis was observed in SSc dermal fibroblasts in vitro.

Treating systemic sclerosis in 2001

Systemic sclerosis (SS) is characterized by sclerosis of the dermis and internal organs and by vascular abnormalities. Although the pathophysiology of the disease has been partly elucidated, the efficacy of long-term treatments remains limited, with no significant increase in survival in prospective studies. Conventional drug treatments are disappointing in clinical practice, and in a recent prospective randomized study standard-dose D-penicillamine was not more effective than mini-dose D-penicillamine. New long-term treatments are emerging for diffuse SS, including cyclophosphamide for patients with progressive interstitial lung disease or stem cell transplantation for those with early organ involvement. The most effective treatments remain symptomatic, such as angiotensin-converting enzyme inhibitors for acute renal crisis, calcium channel antagonists for Raynaud's phenomenon, and proton pump inhibitors for the complications of gastroesophageal reflux. This review article focuses on long-term treatments that are most likely to be effective and suggests symptomatic treatment strategies tailored to specific organ involvements.

Porphyromonas gingivalis gingipain-R enhances interleukin-8 but decreases gamma interferon-inducible protein 10 production by human gingival fibroblasts in response to T-cell contact

Proteases produced by Porphyromonas gingivalis, an oral pathogen, are considered important virulence factors and may affect the responses of cells equipped with proteinase-activated receptors. The aim of this study was to investigate the effect of the arginine-specific cysteine protease gingipain-R produced by P. gingivalis on chemokine production by human gingival fibroblasts (HGF) and the effect of gingipain-R treatment on the subsequent contact-dependent activation of HGF by T cells. HGF incubated in the presence of purified 47-kDa gingipain-R showed increased levels of interleukin-8 (IL-8) mRNA. Cyclooxygenase-2 (COX-2) mRNA was also induced. Further exposure of HGF to activated T cells resulted in the dose- and time-dependent enhancement of IL-8 transcription and release. T-cell membrane-bound tumor necrosis factor (TNF) was the ligand inducing IL-8 production by HGF, since TNF neutralization abrogated HGF responses to T-cell contact. The enhanced IL-8 release was due, at least in part, to prostaglandin-E(2) production, which was mostly blocked by indomethacin. Gingipain-R proteolytic activity was required since heat inactivation, specific synthetic protease inhibitors, and the natural substrate competitor histatin 5 abrogated its effects. The enhanced production of IL-8 in response to T-cell contact was specific since monocyte chemotactic protein-1 (MCP-1) production was unaffected while interferon-gamma-inducible protein-10 (IP-10) was inhibited. The sum of these activities may result in the recruitment of differential cell types to sites of inflammation since IL-8 preferentially recruits neutrophils and IP-10 attracts activated T cells and may be relevant to the pathogenesis of periodontitis.

IL-12 attenuates bleomycin-induced pulmonary fibrosis

Interleukin (IL)-12 is a potent inducer of interferon (IFN)-gamma. We postulated that IL-12 would attenuate bleomycin-induced pulmonary fibrosis. To test this hypothesis, we administered IL-12 or murine serum albumin to bleomycin-treated mice by daily intraperitoneal injection until day 12. Mice treated with IL-12 demonstrated decreased hydroxyproline levels compared with control treated mice. Furthermore, administration of IL-12 led to a time-dependent increase in both lung and bronchoalveolar lavage fluid IFN-gamma. The antifibrotic effect of IL-12 could be attenuated with simultaneous administration of neutralizing anti-IFN-gamma antibodies. These findings support the notion that IL-12 attenuates bleomycin-induced pulmonary fibrosis via modulation of IFN-gamma production.

Potential contribution of IL-17-producing Th(1)cells to defective repair activity in joint inflammation: partial correction with Th(2)-promoting conditions

To assess the contribution of cell interactions to the production of cytokines and type I collagen, fixed synovium T cell clones were cocultured on synoviocytes and levels of IL-6, LIF and PICP, a marker of type I collagen synthesis measured. Levels of IL-6 and LIF were higher with Th(1)than with Th(0)and Th(2)clones. Levels of PICP were decreased with Th(1)clones and increased with Th(2)clones. IL-17-producing T cells, all Th(1), were among the highest inducers of cytokine and inhibitors of collagen synthesis. Preincubation of clones in Th(1)conditions (IL-12 plus anti-IL-4) increased IL-6 production, whereas Th(2)conditions (IL-4 plus anti-IL-12) strongly inhibited IL-6 production and restored repair activity. As rheumatoid synovium is infiltrated by Th(1)cells, local cell interactions result in a pro-inflammatory pattern with defective repair, which can be reversed at least in part, by a Th(2)pattern.

The role of the immune system in conjunctival wound healing after glaucoma surgery

The immune system has a fundamental role in the development and regulation of ocular healing, which plays an important role in the pathogenesis of most blinding diseases. This review discusses the mechanisms of normal wound healing, describing the animal and fetal wound healing models used to provide further insight into normal wound repair. In particular, conjunctival wound repair after glaucoma filtration surgery will be used to illustrate the contributions that the different components of the immune system make to the healing process. The potential role of macrophages, the possible regulatory effect of lymphocytes, and the important role of growth factors and cytokines in the wound healing reaction are discussed. The significance of the immune system in the pathogenesis of aggressive conjunctival scarring is addressed, particularly assessing the predisposing factors, including drugs, age, and ethnicity. The rationale behind the pharmacological agents currently used to modulate the wound healing response and the effects these drugs have on the function of the immune system are described. Finally, potential new therapeutic approaches to regulating the wound healing response are reported.

T-cell-dependent fibrosis in the mdx dystrophic mouse

In Duchenne muscular dystrophy patients, the pathological hallmark of the disease, namely, the chronic accumulation of sclerotic scar tissue in the interstitial space of skeletal muscle is attributed to manifestation of secondary pathological processes. Such anomalous generation of matrix protein is thought to be driven by the continuous degeneration and regeneration of muscle both in Duchenne Muscular Dystrophy and in the mdx mouse homolog. We examined mdx and the control strain C57bl/10 mice over a range of ages with respect to the amounts of collagen present in muscles and other organs, finding that the mdx have significantly higher collagen content at later time points in their kidney and lung as well as their muscles. Surprisingly, when we bred the mdx mice on the nu/nu background, the time course of fibrogenesis was modified depending on the tissue and the collagen content was significantly different in age-matched mice. Transplantation of normal thymic tissue into the mdx-nu/nu mice replenished their T-cells and concomitantly altered the collagen content in their tissues to levels comparable with those in immunocompetent mdx mice. This suggests that T-cells play a role in the onset of the fibrotic events that undermines the ability of dystrophic muscle to regenerate.