Occurrence of an activated, profibrotic pattern of gene expression in lung CD8+ T cells from scleroderma patients

Stimulation with type I collagen induces changes in gene expression in peripheral blood mononuclear cells from patients with diffuse cutaneous systemic sclerosis (scleroderma)

An autoantigenic role for collagen type I (CI) has been suggested previously in diffuse cutaneous systemic sclerosis (dcSSc). Whether CI is indeed capable of affecting the immune system in dcSSc is not known. Patients with early (3 years or less) or late (>3 years) dcSSc and healthy controls donated blood. Peripheral blood mononuclear cells (PBMC) were cultured with or without CI, and expression of genes known for their involvement in autoimmune and inflammatory processes was assessed using cDNA arrays; results were confirmed by real-time polymerase chain reaction and enzyme-linked immunosorbent assay for selected genes. Patients with early and late dcSSc were similarly different from healthy controls in basal gene expression. When cultured with CI, PBMC from patients with early dcSSc differed from healthy controls in expression of 34 genes, whereas PBMC from patients with late dcSSc differed from healthy controls in expression of only 29 genes. Direct comparisons of matched PBMC samples cultured with and without CI revealed differences in expression of eight genes in healthy controls, of five genes in patients with early dcSSc, and no differences in patients with late dcSSc. Thus, PBMC from patients with dcSSc respond differently than do PBMC from healthy controls when cultured with CI. Exposure to CI in culture of PBMC from patients in the early stage of dcSSc in contrast to PBMC from patients with late-stage dcSSc evokes a greater degree of activation of immune-related genes, suggesting that CI is more dominant as an autoantigen in early versus late dcSSc.

Immunotherapy of systemic sclerosis

Scleroderma is a multisystem autoimmune disease characterized by an abnormal immune activation associated with the development of underlying vascular and fibrotic disease manifestations. This article highlights the current use of drugs targeting the immune system in scleroderma. Nonselective immunosuppression, and in particular cyclophosphamide, remains the main treatment for progressing skin involvement and active interstitial lung disease. Mycophenolate mofetil is a promising alternative to cyclophosphamide. The use of cyclosporine has been limited by modest efficacy and serious renal toxicity. Newer T-cell (sirolimus and alefacept) and B-cell (rituximab)-targeted therapies have provided some encouraging results in small pilot studies. Hematopoietic stem cell transplantation can be effective for severe fibrotic skin disease, but toxicity remains a concern. Clinical efficacy and safety of antifibrotic treatments (e.g., imatinib) await confirmation. Newer biological agents targeting key molecular or cellular effectors in scleroderma pathogenesis are now available for clinical testing.

Recent advances and opportunities in research on lupus: environmental influences and mechanisms of disease

We summarize research on mechanisms through which environmental agents may affect the pathogenesis of lupus, discuss three exposures that have been the focus of research in this area, and propose recommendations for new research initiatives. We examined studies pertaining to key mechanistic events and specific exposures. Apoptosis leading to increased production or decreased clearance of immunogenic intracellular self-antigens and defective apoptosis of autoreactive immune cells both have been implicated in the loss of self-tolerance. The adjuvant or bystander effect is also needed to produce a sustained autoimmune response. Activation of toll-like receptors is one mechanism through which these effects may occur. Abnormal DNA methylation may contribute to the pathogenesis of lupus. Each of the specific exposures has been shown, in humans or in mice, to act upon one or more of these pathogenic steps. Specific recommendations for the continued advancement of our understanding of environmental influences on lupus and other autoimmune diseases include the development and use of mouse models with varying degrees of penetrance and manifestations of disease, identification of molecular or physiologic targets of specific exposures, development and use of improved exposure assessment methodologies, and multisite collaborations designed to examine understudied environmental exposures in humans.

Granzyme B cleavage of autoantigens in autoimmunity

The systemic autoimmune diseases are a complex group of disorders characterized by elaboration of high titer autoantibodies and immune-mediated damage of tissues. Two striking features of autoimmune rheumatic diseases are their self-sustaining nature and capacity for autoamplification, exemplified by disease flares. These features suggest the presence of a feed-forward cycle in disease propagation, in which immune effector pathways drive the generation/release of autoantigens, which in turn fuel the immune response. There is a growing awareness that structural modification during cytotoxic granule-induced cell death is a frequent and striking feature of autoantigens, and may be an important principle driving disease. This review focuses on granzyme B (GrB)-mediated cleavage of autoantigens including (i) features of GrB cleavage sites within autoantigens, (ii) co-location of cleavage sites with autoimmune epitopes, and (iii) GrB sensitivity of autoantigens in disease-relevant target tissue. The mechanisms whereby GrB-induced changes in autoantigen structure may contribute to the initiation and propagation of autoimmunity are reviewed and reveal that GrB has the potential to create or destroy autoimmune epitopes. As there remains no direct evidence showing a causal function for GrB cleavage of antigens in the generation of autoimmunity, this review highlights important outstanding questions about the function of GrB in autoantigen selection.

Regulation of pulmonary inflammation and fibrosis through expression of integrins alphaVbeta3 and alphaVbeta5 on pulmonary T lymphocytes

OBJECTIVE

Pulmonary diseases associated with fibrosis, including scleroderma lung disease, are characterized by the accumulation of T cells in the lungs. These cells are thought to facilitate lung fibrosis, but the exact mechanisms of their profibrotic action are not clear. Several alphaV-containing integrins, including alphaVbeta3 and alphaVbeta5, have been shown to directly activate transforming growth factor beta (TGFbeta) and promote collagen accumulation. The aim of this study was to investigate whether pulmonary T cells express profibrotic integrins and regulate collagen accumulation.

METHODS

Expression of integrins was assessed by immunohistochemical analysis of lung tissue, by flow cytometry using bronchoalveolar lavage fluid from patients with systemic sclerosis (SSc), and in a CCL18 overexpression animal model of pulmonary T cell infiltration. Experiments in cell cultures were performed to determine whether integrin-expressing T cells are profibrotic in cocultures with pulmonary fibroblasts and, if so, through what possible mechanism.

RESULTS

Lymphocytes and integrin-positive cells were present in the lungs, and pulmonary T cells expressed integrins alphaVbeta3 and alphaVbeta5 in patients with SSc and in the animal model. Systemic administration of neutralizing anti-integrin alphaV antibody or a genetic deficiency of integrin beta3 in the CCL18 overexpression model significantly attenuated CCL18-driven pulmonary lymphocytic infiltration and collagen accumulation. Jurkat T cells overexpressing integrin alphaVbeta3 or integrin alphaVbeta5 in cocultures with primary pulmonary fibroblasts stimulated collagen accumulation and Smad2 nuclear translocation. Neutralizing anti-TGFbeta antibody attenuated the profibrotic effect of integrin-expressing T cells.

CONCLUSION

Pulmonary infiltrating T lymphocytes may express integrins alphaVbeta3 and alphaVbeta5 that are necessary for lymphocytic infiltration and T cell-associated TGFbeta activation and collagen accumulation.

Selective oxidation of DNA topoisomerase 1 induces systemic sclerosis in the mouse

Systemic sclerosis (SSc) is a connective tissue disorder of great clinical heterogeneity. Its pathophysiology remains unclear. Our aim was to evaluate the relative roles of reactive oxygen species (ROS) and of the immune system using an original model of SSc. BALB/c and immunodeficient BALB/c SCID mice were injected s.c. with prooxidative agents (hydroxyl radicals, hypochlorous acid, peroxynitrites, superoxide anions), bleomycin, or PBS everyday for 6 wk. Skin and lung fibrosis were assessed by histological and biochemical methods. Autoantibodies were detected by ELISA. The effects of mouse sera on H(2)O(2) production by endothelial cells and on fibroblast proliferation, and serum concentrations in advanced oxidation protein products (AOPP) were compared with sera from patients with limited or diffuse SSc. We observed that s.c. peroxynitrites induced skin fibrosis and serum anti-CENP-B Abs that characterize limited SSc, whereas hypochlorite or hydroxyl radicals induced cutaneous and lung fibrosis and anti-DNA topoisomerase 1 autoantibodies that characterize human diffuse SSc. Sera from hypochlorite- or hydroxyl radical-treated mice and of patients with diffuse SSc contained high levels of AOPP that triggered endothelial production of H(2)O(2) and fibroblast hyperproliferation. Oxidized topoisomerase 1 recapitulated the effects of whole serum AOPP. SCID mice developed an attenuated form of SSc, demonstrating the synergistic role of the immune system with AOPP in disease propagation. We demonstrate a direct role for ROS in SSc and show that the nature of the ROS dictates the form of SSc. Moreover, this demonstration is the first that shows the specific oxidation of an autoantigen directly participates in the pathogenesis of an autoimmune disease.

Histopathology and bronchoalveolar lavage

Although neither lung biopsy nor bronchoalveolar lavage (BAL) is recommended for routine clinical use in patients with SSc, studies employing lung biopsy material and BAL fluid (BALF) have provided insight into the pathogenesis of scleroderma-associated interstitial lung disease (SSc-ILD). Most often, SSc-ILD is classified as a non-specific interstitial pneumonia, with abundant myofibroblasts and evidence of both epithelial cell and endothelial cell injury. Recently, SSc-ILD fibroblasts have been shown to express reduced levels of the caveolin-1 protein which, in turn, may lead to activation of the signalling molecules associated with increased collagen production and overexpression of alpha-smooth muscle cell actin (alpha-SMA). BALF often contains increased numbers of inflammatory cells as well as myofibroblasts expressing alpha-SMA. Analysis of BALF suggests an imbalance between pro-fibrotic and anti-fibrotic factors, e.g. an overabundance of TGF-beta, connective tissue growth factor (CTGF), PDGF, leucotriene B4, etc. and in some cases a deficiency of hepatocyte growth factor, 15-hydroxyeicosatetraenoic acid (15-HETE), lipoxin A, etc. Until the pathogenesis is fully understood, lung biopsy and BAL will remain useful research tools to better understand the inflammatory and fibrosing processes that underlie SSc-ILD.

Renal ischemia-reperfusion leads to long term infiltration of activated and effector-memory T lymphocytes

It is well-established that significant ischemia-reperfusion injury during kidney transplantation results in increased incidence of long-term fibrosis and rejection. To test for a role of T cell infiltration and activation following ischemic injury, we induced both bilateral and unilateral renal ischemia in mice, followed by reperfusion, and then isolated mononuclear cells. Analysis of these cells by flow cytometry showed that 2 weeks after bilateral ischemia there was a significant increase of CD8(+) T cells. Furthermore, both CD4(+) and CD8(+) T cells infiltrated the injured kidney 6 weeks after unilateral ischemia. These T cells had increased expression of CD69(+) and CD44(hi)CD62L(-), markers of activation and effector-memory, respectively. CD4(+)NK1.1(+) and CD19(+) B cells were decreased in percentage both 6 and 11 weeks after bilateral or unilateral injury. There was a significant upregulation of IL-1beta, IL-6, TNF-alpha, IFN-gamma, MIP-2, and RANTES expression, measured by real-time PCR, 6 weeks after unilateral renal ischemia, further indicating T cell activation. Depletion of CD4(+) and CD8(+) T cells before ischemia caused less medullary damage and reduced kidney IFN-gamma expression, whereas their depletion following ischemia increased kidney IL-1beta; however, depletion of these cells had no effect on histological damage to the kidney. Our study demonstrates that moderate or severe kidney ischemia induces long-term T lymphocyte infiltration and cytokine/chemokine upregulation, leading to kidney structural changes.

Mechanisms of oncostatin M-induced pulmonary inflammation and fibrosis

Oncostatin M (OSM), an IL-6 family cytokine, has been implicated in a number of biological processes including the induction of inflammation and the modulation of extracellular matrix. In this study, we demonstrate that OSM is up-regulated in the bronchoalveolar lavage fluid of patients with idiopathic pulmonary fibrosis and scleroderma, and investigate the pathological consequences of excess OSM in the lungs. Delivery of OSM to the lungs of mice results in a significant recruitment of inflammatory cells, as well as a dose-dependent increase in collagen deposition in the lungs, with pathological correlates to characteristic human interstitial lung disease. To better understand the relationship between OSM-induced inflammation and OSM-induced fibrosis, we used genetically modified mice and show that the fibrotic response is largely independent of B and T lymphocytes, eosinophils, and mast cells. We further explored the mechanisms of OSM-induced inflammation and fibrosis using both protein and genomic array approaches, generating a "fibrotic footprint" for OSM that shows modulation of various matrix metalloproteinases, extracellular matrix components, and cytokines previously implicated in fibrosis. In particular, although the IL-4/IL-13 and TGF-beta pathways have been shown to be important and intertwined of fibrosis, we show that OSM is capable of inducing lung fibrosis independently of these pathways. The demonstration that OSM is a potent mediator of lung inflammation and extracellular matrix accumulation, combined with the up-regulation observed in patients with pulmonary fibrosis, may provide a rationale for therapeutically targeting OSM in human disease.

Scleroderma gene expression and pathway signatures

Gene expression studies in scleroderma have shown large and consistent changes in the gene expression of end-target tissues. These changes reflect the lymphocyte infiltration and pathway deregulation potentially linked to disease pathogenesis. Gene expression in scleroderma also reflects the clinical heterogeneity in the disease and can be used to categorize patients. Contained within these gene expression signatures are groups of genes that could serve as biomarkers for clinical end points and disease activity. The use of mechanism-derived gene expression signatures in scleroderma will provide a better understanding of the deregulated pathways contributing to disease pathogenesis.

Induction of interferon-alpha by scleroderma sera containing autoantibodies to topoisomerase I: association of higher interferon-alpha activity with lung fibrosis

OBJECTIVE

Peripheral blood cells (PBMCs) from some patients with systemic sclerosis (SSc) express an interferon-alpha (IFNalpha) signature. The aim of this study was to determine whether SSc patient sera could induce IFNalpha and whether IFNalpha induction was associated with specific autoantibodies and/or clinical features of the disease.

METHODS

SSc sera containing autoantibodies against either topoisomerase I (anti-topo I; n = 12), nucleolar protein (ANoA; n = 12), or centromeric protein (ACA; n = 13) were cultured with a HeLa nuclear extract and normal PBMCs. In some experiments, different cell extracts or inhibitors of plasmacytoid dendritic cell (DC) activation, Fcgamma receptor II (FcgammaRII), endocytosis, or nucleases were used. IFNalpha was measured by enzyme-linked immunosorbent assay.

RESULTS

Topo I-containing sera induced significantly higher levels of IFNalpha as compared with all other groups. IFNalpha induction was inhibited by anti-blood dendritic cell antigen 2 (90%), anti-CD32 (76%), bafilomycin (99%), and RNase (82%). In contrast, ACAs induced low levels of IFNalpha even when necrotic, apoptotic, or demethylated extracts were used, despite the fact that CENP-B-binding oligonucleotide containing 2 CpG motifs effectively stimulated IFNalpha. IFNalpha production was significantly higher in patients with diffuse SSc (mean +/- SEM 641 +/- 174 pg/ml) than in those with limited SSc (215 +/- 66 pg/ml) as well as in patients with lung fibrosis than in those without.

CONCLUSION

Autoantibody subsets in SSc sera differentially induce IFNalpha and may explain the IFNalpha signature observed in SSc. IFNalpha is induced by plasmacytoid DCs and required uptake of immune complexes through FcgammaRII, endosomal transport, and the presence of RNA, presumably for interaction with Toll-like receptor 7. The higher IFNalpha induction in sera from patients with diffuse SSc than in those with limited SSc as well as in sera from patients with lung fibrosis suggests that IFNalpha may contribute to tissue injury.

Recent advances and opportunities in research on lupus: environmental influences and mechanisms of disease

OBJECTIVES

In this review we summarize research on mechanisms through which environmental agents may affect the pathogenesis of lupus, discuss three exposures that have been the focus of research in this area, and propose recommendations for new research initiatives.

DATA SOURCES AND SYNTHESIS

We examined studies pertaining to key mechanistic events and specific exposures. Apoptosis leading to increased production or decreased clearance of immunogenic intracellular self-antigens and defective apoptosis of autoreactive immune cells both have been implicated in the loss of self-tolerance. The adjuvant or bystander effect is also needed to produce a sustained autoimmune response. Activation of toll-like receptors is one mechanism through which these effects may occur. Abnormal DNA methylation may also contribute to the pathogenesis of lupus. Each of the specific exposures we examined--Epstein-Barr virus, silica, and trichloroethylene--has been shown, in humans or in mice, to act upon one or more of these pathogenic steps. Specific recommendations for the continued advancement of our understanding of environmental influences on lupus and other autoimmune diseases include the development and use of mouse models with varying degrees of penetrance and manifestations of disease, identification of molecular or physiologic targets of specific exposures, development and use of improved exposure assessment methodologies, and multisite collaborations designed to examine understudied environmental exposures in humans.

CONCLUSIONS

The advances made in the past decade concerning our understanding of mechanisms involved in the development of lupus and the influence of environmental agents on this process provide a strong foundation for further developments in this field.

Macrophages produce TGF-beta-induced (beta-ig-h3) following ingestion of apoptotic cells and regulate MMP14 levels and collagen turnover in fibroblasts

Phagocytic clearance of apoptotic cells by macrophages is an essential part in the resolution of inflammation. It coincides with activation of repair mechanisms, including accumulation of extracellular matrix. A possible link between clearance of apoptotic debris and accumulation of extracellular matrix has not been investigated. Production of collagen was measured in primary fibroblasts cocultured with macrophages. Ingestion of apoptotic cells by monocyte-derived macrophages led to up-regulation of collagen. Direct contact between macrophages and fibroblasts was not required for collagen up-regulation. Macrophages produced TGF-beta following ingestion of apoptotic cells, but the levels of this cytokine were lower than those required for a significant up-regulation of collagen. Simultaneously, the levels of TGF-beta-induced (TGFBI), or keratoepithelin/BIGH3, mRNA and protein were increased. In contrast, primary alveolar macrophages stimulated collagen production without exposure to apoptotic cells; there was no further increase in the levels of TGFBI, mRNA or protein, or collagen after ingestion of apoptotic cells. Stimulation of fibroblasts with TGFBI down-regulated MMP14 levels, decreased DNA binding by p53, increased DNA binding by PU.1, and up-regulated collagen protein but not mRNA levels. Overexpression of MMP14 or p53, or small interfering RNA-mediated inhibition of PU.1 led to an increase in MMP14 and a decline in collagen levels, whereas small interfering RNA-mediated inhibition of MMP14 led to elevation of collagen levels. In conclusion, monocyte-derived but not alveolar macrophages produce TGFBI following ingestion of apoptotic cells, leading to the down-regulation of MMP14 levels in fibroblasts through a mechanism involving p53 and PU.1, and to subsequent accumulation of collagen.

T cell polarization identifies distinct clinical phenotypes in scleroderma lung disease

OBJECTIVE

Lung involvement is the leading cause of morbidity and mortality in systemic sclerosis (SSc; scleroderma), and interstitial lung disease (ILD) is the most common pulmonary manifestation. An abnormal profibrotic Th2/Tc2-polarized T cell response is postulated to mediate tissue damage and fibrosis. The aim of this study was to investigate whether a polarized T cell phenotype in SSc is associated with lung disease or other clinical manifestations of SSc.

METHODS

Circulating T cells were characterized by flow cytometry in 62 patients with SSc and 36 healthy control subjects, using antibodies against CD3, CD4, CD8, chemokine receptor CCR5 (Th1/Tc1-specific), and prostaglandin D2 receptor CRTH2 (Th2/Tc2-specific). The ratio between CCR5 and CRTH2 T cell frequencies was used to quantify type 1 (high-ratio) or type 2 (low-ratio) immune polarization.

RESULTS

Patients with SSc exhibited lower CCR5/CRTH2 T cell ratios than those exhibited by control subjects (P<0.0001), indicating a Th2/Tc2-polarized phenotype. Markedly reduced CCR5/CRTH2 T cell ratios were observed in SSc patients with ILD compared with SSc patients without ILD (P<0.0001), particularly in patients with active ILD (P<0.0001) compared with those with stable lung function. Lower CCR5/CRTH2 ratios were strongly associated with a lower value for the percent predicted forced vital capacity (P<0.0001). In patients with an estimated right ventricular systolic pressure>35 mm Hg, suggestive of pulmonary vascular disease, a lower value for the percent predicted diffusing capacity (DLCO) was associated with higher CCR5/CRTH2 T cell ratios (Th1/Tc1) (P=0.009), while in those with right ventricular systolic pressure<35 mm Hg, a lower value for the percent predicted DLCO correlated with lower ratios (Th2/Tc2) (P<0.0001), as observed for ILD.

CONCLUSION

T cell polarization in SSc is strongly associated with specific manifestations of lung disease. Measurement of T cell polarization may represent a valuable tool to monitor disease activity and predict clinical outcomes in SSc patients with lung disease.

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.

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.

Autoimmunity in systemic sclerosis: current concepts

Systemic sclerosis (SSc) is characterized by tissue fibrosis, obliterative microangiopathy, and immune abnormalities. The role of autoimmunity in generating the clinical and pathologic phenotype in SSc remains uncertain. Distinct subsets of antinuclear antibodies are selectively associated with unique disease manifestations but do not have a proven pathogenic role. A new class of autoantibodies recognizing cellular or extracellular matrix antigens has been recognized in SSc patients. They seem to directly activate pathways that may contribute to SSc-specific tissue and vascular damage. Data confirms that activation and polarization of T cells can contribute to a profibrotic environment. Also, activated immune effector cells can promote vascular obliterative damage through direct cytotoxic pathways targeting the endothelium or by inducing proinflammatory molecules. Technologies are emerging to accurately measure the autoantigen-specific T-cell response in SSc patients. Perturbed B-cell homeostasis has been reported in SSc. If confirmed in-vivo, these advances could lead to new disease-modifying therapeutic strategies directed at SSc-specific immune effector pathways.

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.

Increased bleomycin-induced skin fibrosis in mice lacking the Th1-specific transcription factor T-bet

Fibrosis, the pathological hallmark of scleroderma and related conditions, is due to sustained activation of tissue fibroblasts. Accumulating evidence implicates cytokine networks in initiating, and propagating or terminating fibroblast activation, and the specific cytokine phenotype dictates evolution of the fibrotic response toward either resolution or scarring. In particular, cytokines that promote fibroblast proliferation and myofibroblast differentiation and extracellular matrix (ECM) accumulation functionally define a type 2 (Th2) immune response, whereas interferon-gamma, which suppresses diverse fibroblast activities, defines a type 1 (Th1) immune response. It remains unclear what role the balance between Th1 and Th2 cytokines plays in the pathogenesis of fibrosis. Here we used bleomycin-induced skin fibrosis as a murine model for human scleroderma in order to study the fibrotic response in mice lacking T-bet, a transcription factor that is essential for initiating Th1 lineage development of CD4+ T lymphocytes. Spleen cells from T-bet null (T-bet(-/-)) mice exhibited a typical Th2 cytokine profile ex vivo, with elevated production of interleukin-4 (IL-4), IL-5 and IL-13, and diminished production of interferon-gamma. Bleomycin-induced early mast cells and eosinophil accumulation, and eosinophil degranulation, in the lesional tissue were greater in T-bet(-/-) mice than in wild-type control mice. At a later time point, T-bet(-/-) mice developed significantly more extensive dermal and especially hypodermal fibrosis. Elevated TGF-beta expression and intracellular Smad activation were prominent in lesional skin. Infiltrating eosinophils appeared to be an important cellular source of TGF-beta. These results demonstrate that in mice lacking T-bet bleomycin induced exaggerated skin fibrosis, suggesting that T-bet has an important physiologic role in regulation of tissue repair by promoting Th1 immune responses that prevent excessive ECM accumulation.

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.

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.

Systemic sclerosis: hypothesis-driven treatment strategies

We review data from controlled trials and randomised controlled trials to examine the hypothesis for the pathogenesis of systemic sclerosis. Strategies used to treat the vascular complications in systemic sclerosis have so far shown the biggest successes, especially in the management of renal crisis and pulmonary arterial hypertension. Because these drugs have improved function and quality of life and have increased survival rates, they can truly be classified as disease-modifying compounds. Immunosuppressive therapy with cyclophosphamide in particular has also shown evidence of efficacy, and randomised controlled trials of autologous stem-cell transplantation are underway. So far, strategies to reduce or control fibrosis directly (bosentan, interferon gamma, and relaxin) have been disappointing but new strategies against fibrosis based on advanced understanding of the molecular biology of systemic sclerosis hold promise. Treatments against several cardinal features of the disorder simultaneously have not yet been examined but are being considered for future trials.

PKCalpha mediates CCL18-stimulated collagen production in pulmonary fibroblasts

A CC chemokine, CCL18, has been previously reported to stimulate collagen production in pulmonary fibroblasts. This study focused on the role of protein kinase C (PKC) in the profibrotic signaling activated by CCL18 in pulmonary fibroblasts. Of the three PKC isoforms that are predominantly expressed in fibroblasts (PKCalpha, PKCdelta, and PKCepsilon), two isoforms (PKCdelta and PKCepsilon) have been implicated in profibrotic intracellular signaling. The role of PKCalpha-mediated signaling in the regulation of collagen production remains unclear. In this study, PKCalpha was found mostly in the cytoplasm, whereas PKCdelta and PKCepsilon were found mostly in the nucleus of cultured primary pulmonary fibroblasts. In response to stimulation with CCL18, PKCalpha but not PKCdelta or PKCepsilon underwent rapid (within 5-10 min) transient phosphorylation and nuclear translocation. Inhibition with dominant-negative mutants of PKCalpha and ERK2, but not PKCdelta or PKCepsilon, abrogated CCL18-stimulated ERK2 phosphorylation and collagen production. The effect of CCL18 on collagen production and the activity of collagen promoter reporter constructs were also abrogated by a selective pharmacologic inhibitor of PKCalpha Gö6976. Stimulation of fibroblasts with CCL18 caused an increase in intracellular calcium concentration. Consistent with the known calcium dependence of PKCalpha signaling, blocking of the calcium signaling with the intracellular calcium-chelating agent BAPTA led to abrogation of PKCalpha nuclear translocation, ERK2 phosphorylation, and collagen production. These observations suggest that in primary pulmonary fibroblasts, PKCalpha but not PKCdelta or PKCepsilon mediate the profibrotic effect of CCL18. PKCalpha may therefore become a viable target for future antifibrotic therapies.

Essential role of TNF family molecule LIGHT as a cytokine in the pathogenesis of hepatitis

LIGHT is an important costimulatory molecule for T cell immunity. Recent studies have further implicated its role in innate immunity and inflammatory diseases, but its cellular and molecular mechanisms remain elusive. We report here that LIGHT is upregulated and functions as a proinflammatory cytokine in 2 independent experimental hepatitis models, induced by concanavalin A and Listeria monocytogenes. Molecular mutagenesis studies suggest that soluble LIGHT protein produced by cleavage from the cell membrane plays an important role in this effect through the interaction with the lymphotoxin-beta receptor (LTbetaR) but not herpes virus entry mediator. NK1.1+ T cells contribute to the production, but not the cleavage or effector functions, of soluble LIGHT. Importantly, treatment with a mAb that specifically interferes with the LIGHT-LTbetaR interaction protects mice from lethal hepatitis. Our studies thus identify a what we believe to be a novel function of soluble LIGHT in vivo and offer a potential target for therapeutic interventions in hepatic inflammatory diseases.

Bradykinin B2receptor antagonism attenuates inflammation, mast cell infiltration and fibrosis in remote myocardium after infarction in rats

Bradykinin may interfere with myocardial remodelling by promoting inflammation and mast cell activation or, alternatively, by counteracting angiotensin II-dependent collagen accumulation. The aim of the present study was to investigate the role of bradykinin B2 receptor antagonism in inflammatory and mast cell infiltration, fibroplasia and fibrosis accumulation following myocardial infarction (MI). Myocardial infarction was produced by the ligature of the left coronary artery in male Wistar rats that were 10 weeks of age. Immediately after MI, rats received the B2 receptor antagonist Hoe140 (0.5 microg/kg per min, s.c.) or saline over a period of 3 days, 1 week or 4 weeks, constituting three separate groups and their respective controls. Coronal myocardial tissue sections underwent haematoxylin and eosin, Giemsa and picrosirius red staining, as well as immunohistochemistry for alpha-smooth muscle actin (SMA). Morphometric studies were undertaken in three different myocardial regions: MI, remote non-infarcted subendocardium (non-MI SE) and remote non-infarcted interventricular septum (non-MI IVS). The MI size was comparable between Hoe140-treated groups and their respective controls (day 3: 42 +/- 4%, n = 8, vs 43 +/- 3%, n = 6; week 1: 37 +/- 5%, n = 5, vs 39 +/- 2%, n = 5; week 4: 35 +/- 3%, n = 9, vs 36 +/- 3%, n = 7). At day 3, Hoe140 treatment reduced inflammatory cell reaction within the MI (585 +/- 59 vs 995 +/- 170 cells/mm2; P = 0.02), non-MI SE (77 +/- 12 vs 214 +/- 57 cells/mm2; P = 0.02) and non-MI IVS (93 +/- 16 vs 135 +/- 14 cells/mm2; P = 0.03) regions. Mast cells were reduced within the non-MI IVS region (0.8 +/- 0.1 vs 2.5 +/- 0.4 cells/mm2; P = 0.006), but not within the MI region. In non-MI SE, mast cells were rarely found. At week 1, Hoe140 treatment reduced alpha-SMA-positive myofibroblast infiltration within the MI (2535 +/- 383 vs 5636 +/- 968 cells/mm2; P = 0.01) and non-MI SE (222 +/- 33 vs 597 +/- 162 cells/mm2; P = 0.03) regions. In the non-MI IVS region, alpha-SMA-positive myofibroblasts were rarely found. At week 4, Hoe140 treatment reduced collagen volume fraction within the MI (37 +/- 4 vs 53 +/- 4%; P = 0.03), non-MI SE (1.3 +/- 0.2 vs 2.6 +/- 0.3%; P = 0.001) and non-MI IVS (1.1 +/- 0.2 vs 1.8 +/- 0.2%; P = 0.01) regions. Bradykinin promotes inflammation, fibroplasia and fibrosis after MI. Mast cells may have a role in fibrosis deposition through a bradykinin-related mechanism.

Signatures of differentially regulated interferon gene expression and vasculotrophism in the peripheral blood cells of systemic sclerosis patients

OBJECTIVE

To obtain a global view of the immunological alterations occurring in early systemic sclerosis (SSc) by transcriptional profiling of peripheral blood cells (PBCs).

METHODS

Oligonucleotide microarrays were used to compare PBC gene expression profiles in 18 SSc cases (<2 yr duration) and 18 controls matched for race, gender and ethnicity. SSc cases had no prior or current exposure to cytotoxic drugs. PAXgene tubes were used to stabilize RNA during phlebotomy. Changes in gene expression were independently validated by real-time polymerase chain reaction.

RESULTS

SSc PBCs demonstrated differential expression of 18 interferon-inducible genes. Six of these genes were identical to the interferon signature genes in lupus peripheral blood mononuclear cells. Notably, SSc PBCs also had increased expression of allograft inflammatory factor (AIF1) and several selectins and integrins involved in cellular adhesion to the endothelium. Global analysis of 284 known biological pathways revealed that 13 were differentially regulated in SSc PBCs, including two pathways (IL2RB and GATA3) that lead to T(H)2 polarization.

CONCLUSIONS

Transcriptional profiling reliably discriminates between PBCs from SSc and normal donors despite the fact that they represent a heterogeneous cell population. Multiple biological pathways were differentially regulated in SSc PBCs, but a common thread across these pathways was alterations in protein tyrosine kinase 2beta and mitogen-activated protein kinase signalling. Although the SSc PBC gene expression profile demonstrated some parallels with the lupus interferon gene signature, there was also increased expression of transcripts encoding proteins that target PBCs to the endothelium, which might be relevant to the vasculopathy of SSc.

Induction of prolonged infiltration of T lymphocytes and transient T lymphocyte–dependent collagen deposition in mouse lungs following adenoviral gene transfer of CCL18

OBJECTIVE

Levels of CCL18 are elevated in patients with scleroderma lung disease and other fibrotic pulmonary diseases associated with T lymphocyte involvement. We sought to determine whether CCL18 alone can induce pulmonary T lymphocytic infiltration and fibrosis in mouse lungs.

METHODS

An adenovirus vector was constructed and used for CCL18 delivery to mouse lungs in vivo. Immunohistochemical, flow cytometric, and enzyme-linked immunosorbent assay analyses were used to assess the resulting changes.

RESULTS

Overexpression of CCL18 led to massive perivascular and peribronchial infiltration of T lymphocytes. Although the expression of CCL18 peaked on day 7, the infiltration persisted up to day 64 after infection. The infiltrates were negative for proliferating cell nuclear antigen and TUNEL, suggesting the role of cell trafficking, rather than proliferation and apoptosis, in the infiltration dynamics. Patchy destruction of the alveolar architecture and collagen accumulation in association with the infiltrates were also noticed. These changes were infiltration-dependent, rather than CCL18-dependent, since treatment with antilymphocyte serum completely abrogated the CCL18-induced changes. The infiltrates consisted almost exclusively of T lymphocytes that were minimally activated, with a minimal increase in the expression of CD69 and no changes in the expression of CD25, Fas, FasL, or CD40L. There was no increase in total pulmonary levels of profibrotic cytokines transforming growth factor beta1 (TGFbeta1) or interleukin-13, although active TGFbeta1 was present locally in association with the infiltrates and areas of distorted alveolar architecture. Prestimulation of primary T lymphocytes with CCL18 in vitro caused an up-regulation of TGFbeta1 and collagen production in T lymphocyte/fibroblast cocultures.

CONCLUSION

CCL18 promotes selective, long-term pulmonary infiltration of T lymphocytes and infiltration-dependent accumulation of collagen through a TGFbeta1-dependent mechanism.

Expression of oncostatin M and its receptors in normal and cirrhotic human liver

BACKGROUND/AIMS

In the cirrhotic liver, gene expression of the multifunctional cytokine oncostatin M (OSM) is up-regulated, but its cellular origin is unknown. Therefore, we investigated the expression of OSM protein and its specific receptor subunits, OSMRbeta and LIFRbeta in normal and cirrhotic human liver using immunohistochemical and Western blot analysis.

RESULTS

OSM protein was expressed in Kupffer cells, variably in normal liver but consistently in cirrhosis. OSMRbeta was expressed at low level in hepatocytes of all normal livers examined, but in no cirrhotic sample. In contrast, LIFRbeta receptor was expressed weakly in normal livers, but much more intensely in cirrhosis, in reactive ductules, bile duct epithelial cells and perisinusoidal areas. Double immunostaining showed co-localization of LIFRbeta with cytokeratin 7, proliferating cell nuclear antigen (PCNA) and leukemia inhibitory factor (LIF), in bile duct epithelial cells, but not with alpha-smooth muscle actin, a myofibroblast marker.

CONCLUSIONS

In human liver, OSM protein is expressed in Kupffer cells, variably in normals but universally in cirrhosis. The differential expression pattern of OSM and its receptors could allow for differential OSM signaling by alternative utilization of receptors to promote hepatocyte proliferation in acute injury and, with its homologue LIF, for the bile ductular reaction in cirrhosis.

Transplant-related bronchiolitis obliterans (BOS) demonstrates unique cytokine profiles compared to toxicant-induced BOS

Bronchiolitis obliterans (BOS - bronchiolitis obliterans syndrome - clinical diagnosis; CBO-histopathologic diagnosis), is a chronic disease process of fibrosis and cellular deposition in airways, complicating long term survival following lung transplantation. BOS is also the result of sporadic toxicant exposure, with airway signs, symptoms, and histology indistinguishable from allograft rejection. This study establishes a transplant BOS model in MHC-mismatched rats and compares their cytokine profiles and histopathology to that of our established toxicant-induced BOS model. Both models result in lung histopathology similar to human disease. Cytokines and inflammation markers that are elevated in human transplant BOS (TGFbeta, iNOS, IFNgamma) were also elevated significantly in both models. Anti-nuclear antibody was absent from all sera in transplant or toxicant models exhibiting advanced airway pathology. The cytokine osteopontin was highly elevated in BAL early in toxicant-induced BOS, but increased late in the transplant-induced BOS model. The data show that BOS is a disease of a pathologic endpoint that is induced by different triggers and processes. The highly elevated BAL osteopontin early in the toxicant-induced BOS model suggests a need for evaluation in the diagnostic setting.

Scleroderma: from cell and molecular mechanisms to disease models

Scleroderma [also known as systemic sclerosis (SSc)] is a complex autoimmune disease characterised by pathological remodelling of connective tissues. Although the earliest and most frequent manifestations include blood vessel and immunological abnormalities, the systemic and progressive pathology suggests that fundamental interactions between microvascular damage and inflammation are mechanistically linked to obliterative tissue fibrosis. This review will focus on how model systems have provided clues to these relationships and will discuss new data from the study of novel animal disease models. These reveal how vascular damage and leukocyte accumulation generate the molecular cues that control the profiles of soluble mediators, which regulate the aberrant behaviour of mesenchymal cells within connective tissues, and how the dysregulated expression of these components and their differentiation contribute to the persistent fibrogenic response.

BMP-7 opposes TGF-beta1-mediated collagen induction in mouse pulmonary myofibroblasts through Id2

Mesenchymal cells, primarily fibroblasts and myofibroblasts, are the principal matrix-producing cells during pulmonary fibrogenesis. Transforming growth factor (TGF)-beta signaling plays an important role in stimulating the expression of type I collagen of these cells. Bone morphogenetic protein (BMP)-7, a member of the TGF-beta superfamily, has been reported to oppose the fibrogenic activity of TGF-beta1. Here, we have addressed the effects of BMP-7 on the fibrogenic activity of pulmonary myofibroblasts. We first established cell lines from the lungs of transgenic mice harboring the COL1A2 upstream sequence fused to luciferase. They displayed a spindle shape and expressed vimentin and alpha-smooth muscle actin, but not E-cadherin. COL1A2 promoter activity was dose dependently induced by TGF-beta1, which was further augmented by adenoviral overexpression of Smad3, but was downregulated by Smad7. Under the identical condition, adenoviral overexpression of BMP-7 attenuated the TGF-beta1-dependent COL1A2 promoter activity. By immunocytochemistry, the ectopic expression of BMP-7 led to the nuclear localization of phospho-Smad1/5/8 and suppressed that of Smad3. BMP-7 suppressed the expression of mRNAs for COL1A2 and tissue inhibitor of metalloproteinase-2 while increasing those of inhibitors of differentiation (Id) 2 and 3. Ectopic expression of Id2 and Id3 was found to decrease the COL1A2 promoter activity. Finally, BMP-7 and Id2 decreased TGF-beta1-dependent collagen protein secretion. In conclusion, these data demonstrate that BMP-7 antagonizes the TGF-beta1-dependent fibrogenic activity of mouse pulmonary myofibroblastic cells by inducing Id2 and Id3.

Up regulated expression of tumour necrosis factor {alpha} converting enzyme in peripheral monocytes of patients with early systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is accompanied by abnormalities in humoral and cellular immune systems.

OBJECTIVE

To determine the genes specifically expressed in the immune system in SSc by analysis of the gene expression profile of peripheral blood mononuclear cells (PBMC) from patients with SSc, including those treated with haematopoietic stem cell transplantation (HSCT). Additionally, to investigate the clinical significance of the up regulation of tumour necrosis factor alpha (TNFalpha) converting enzyme (TACE).

METHODS

PBMC from patients with SSc (n = 23) and other autoimmune diseases (systemic lupus erythematosus (SLE, n = 16), rheumatoid arthritis (RA, n = 29)), and from disease-free controls (n = 36) were examined. Complementary DNA arrays were used to evaluate gene expression of PBMC, in combination with real time quantitative polymerase chain reactions. TACE protein expression in PBMC was examined by fluorescence activated cell sorter (FACS).

RESULTS

In patients with SSc 118 genes were down regulated after HSCT. Subsequent comparative analysis of SSc without HSCT and healthy controls indicated SSc-specific up regulation for three genes: monocyte chemoattractant protein-3 (p = 0.0015), macrophage inflammatory protein 3alpha (p = 0.0339), and TACE (p = 0.0251). In the FACS analysis, TACE protein was mainly expressed on CD14(+) monocytes both in patients with SSc and controls. TACE expression on CD14(+) cells was significantly increased in patients with early SSc (p = 0.0096), but not in those with chronic SSc, SLE, or RA. TACE protein levels in SSc monocytes correlated with the intracellular CD68 levels (p = 0.0016).

CONCLUSIONS

Up regulation of TACE expression was a unique profile in early SSc, and may affect the function of TNFalpha and other immunoregulatory molecules.

CD8+ T lymphocytes in lung tissue from patients with idiopathic pulmonary fibrosis

Background

Several studies have implicated a role of inflammation in the pathogenesis of lung damage in idiopathic pulmonary fibrosis (IPF). Parenchymal lung damage leads to defects in mechanics and gas exchange and clinically manifests with exertional dyspnea. Investigations of inflammatory cells in IPF have shown that eosinophils, neutrophils and CD₈₊ TLs may be associated with worse prognosis. We wished to investigate by quantitative immunohistochemistry infiltrating macrophages, neutrophils and T lymphocytes (TLs) subpopulations (CD₃₊, CD₄₊ and CD₈₊) in lung tissue of patients with IPF and their correlation with lung function indices and grade of dyspnoea.

Methods

Surgical biopsies of 12 patients with IPF were immunohistochemically stained with mouse monoclonal antibodies (anti-CD₆₈ for macrophages, anti-elastase for neutrophils, and anti-CD₃, anti-CD₄, anti-CD₈ for CD₃₊TLs, CD₄₊TLs, and CD₈₊TLs respectively). The number of positively stained cells was determined by observer-interactive computerized image analysis (SAMBA microscopic image processor). Cell numbers were expressed in percentage of immunopositive nuclear surface in relation to the total nuclear surface of infiltrative cells within the tissue (labeling Index). Correlations were performed between cell numbers and physiological indices [FEV₁, FVC, TLC, DLCO, PaO₂, PaCO₂ and P(A-a)O₂)] as well as dyspnoea scores assessed by the Medical Research Council (MRC) scale.

Results

Elastase positive cells accounted for the 7.04% ± 1.1 of total cells, CD₆₈₊ cells for the 16.6% ± 2, CD₃₊ TLs for the 28.8% ± 7, CD₄₊ TLs for the 14.5 ± 4 and CD₈₊ TLs for the 13.8 ± 4. CD₈₊TLs correlated inversely with FVC % predicted (r_s = -0.67, p = 0.01), TLC % predicted (r_s = -0.68, p = 0.01), DLCO % predicted (r_s = -0.61, p = 0.04), and PaO₂ (r_s = -0.60, p = 0.04). Positive correlations were found between CD₈₊TLs and P(A-a)O₂ (r_s = 0.65, p = 0.02) and CD₈₊TLs and MRC score (r_s = 0.63, p = 0.02). Additionally, CD₆₈₊ cells presented negative correlations with both FVC % predicted (r_s = -0.80, p = 0.002) and FEV₁ % predicted (r_s = -0.68, p = 0.01).

Conclusion

In UIP/IPF tissue infiltrating mononuclear cells and especially CD₈₊ TLs are associated with the grade of dyspnoea and functional parameters of disease severity implicating that they might play a role in its pathogenesis.

CCL18-stimulated upregulation of collagen production in lung fibroblasts requires Sp1 signaling and basal Smad3 activity

A CC chemokine CCL18 stimulates collagen production in pulmonary fibroblasts through an unknown signaling mechanism. In this study, involvement of Sp1 and Smad3 in CCL18 signaling in primary human pulmonary fibroblast cultures was investigated. Phosphorylation of Sp1, DNA-binding by Sp1, and the activity of an Sp1-dependent reporter were all increased in response to CCL18 stimulation. CCL18 did not stimulate a detectable increase in Smad3 phosphorylation or Smad3/4 DNA-binding activity, although some basal phosphorylation and DNA binding by Smad3/4 were noted. Transient overexpression of dominant negative mutants of Sp1 and Smad3 abrogated CCL18-dependent upregulation as well as basal production of collagen. These observations suggested that CCL18 activates collagen production in pulmonary fibroblasts through an Sp1-dependent pathway that also requires basal Smad3 activity. Possible involvement of autocrine TGF-beta in CCL18 signaling was considered. CCL18 stimulated increases in collagen mRNA and protein production without detectable changes in TGF-beta1, -beta2, and -beta3 mRNA or protein levels. Neutralizing anti-TGF-beta antibodies, latency-associated peptide, ALK5-specific inhibitor SD431542, and an inhibitor of the protease-dependent TGF-beta activation aprotinin, each failed to block CCL18-stimulated collagen production. These observations suggest that both CCL18 signaling in pulmonary fibroblasts and basal Smad3 activity are independent of autocrine TGF-beta.

Comparative studies of oncostatin M expression in the tissues of adult rodents

Oncostatin M (OSM), a member of the interleukin-6 family of cytokines, is thought to be expressed mostly by activated T-lymphocytes and monocytes in adult animals. However, here we report specific constitutive tissue expression of OSM in the pancreas, kidney, testes, spleen, stomach, and brain, but not liver or lung, of three adult rodent species.

Advances in the treatment of rheumatic interstitial lung disease

PURPOSE OF REVIEW

Interstitial lung disease frequently complicates the rheumatic diseases. The purpose of this review is to outline recent advances and current concepts regarding the management of these interstitial lung diseases.

RECENT FINDINGS

Several histologic lesions cause interstitial lung disease in rheumatic diseases, including nonspecific interstitial pneumonia, usual interstitial pneumonia, organizing pneumonia, lymphocytic interstitial pneumonia, desquamative interstitial pneumonia, and acute interstitial pneumonia. Although the relative frequency of occurrence of these histopathologic lesions is not definitively established, it seems that nonspecific interstitial pneumonia accounts for a large proportion of rheumatic disease-associated interstitial lung diseases. Although usual interstitial pneumonia generally responds poorly to corticosteroid therapy, other forms of interstitial pneumonia are often steroid responsive and have a more favorable long-term prognosis. Pulmonary hypertension is increasingly recognized as a complication of these interstitial lung diseases. Treatment of pulmonary hypertension in these patients provides clinical benefit and may suppress pulmonary inflammation and fibrosis. Lung transplantation is a treatment option for selected patients with severe pulmonary involvement and limited life expectancy.

SUMMARY

Interstitial lung disease is common in the rheumatic diseases, may be caused by a variety of lesions that respond differently to treatment, and may lead to the development of pulmonary hypertension. Whether the prognosis of interstitial lung disease associated with rheumatic disease is similar to that associated with the idiopathic interstitial pneumonias is not known. Treatment of these interstitial lung diseases should take into account the specific histologic lesion, the activity of the underlying rheumatic disease, and associated pulmonary hypertension, if present. The diagnosis of a rheumatic disease is no longer an absolute contraindication to lung transplantation.