Update on pathophysiology of scleroderma with special reference to immunoinflammatory events

Renal Involvement in Systemic Sclerosis: An Update

BACKGROUND

Systemic sclerosis is an immune-mediated rheumatic disease characterized by vascular abnormalities, tissue fibrosis and autoimmune phenomena.

SUMMARY

Renal disease occurring in patients with systemic sclerosis may have a variable clinicopathological picture. The most specific renal condition associated with systemic sclerosis is scleroderma renal crisis, characterized by acute onset of renal failure and severe hypertension. Although the management of scleroderma renal crisis was revolutionized by the introduction of angiotensin-converting enzyme inhibitors, there is still a significant proportion of patients with poor outcomes. Therefore, research on establishing disease markers (clinical, ultrasonographical and serological) and clear diagnostic criteria, which could limit the risk of developing scleroderma renal crisis and facilitate diagnosis of this complication, is ongoing. Other forms of renal involvement in systemic sclerosis include vasculitis, an isolated reduced glomerular filtration rate in systemic sclerosis, antiphospholipid-associated nephropathy, high intrarenal arterial stiffness and proteinuria. Key Messages: Scleroderma renal crisis is the most specific and life-threatening renal presentation of systemic sclerosis, albeit with declining prevalence. In patients with scleroderma renal crisis, it is mandatory to control blood pressure early with increasing doses of angiotensin-converting enzyme inhibitors, along with other antihypertensive drugs if necessary. There is a strong association between renal involvement and patients' outcomes in systemic sclerosis; consequently, it becomes mandatory to find markers that may be used to identify patients with an especially high risk of scleroderma renal crisis.

Thrombotic Microangiopathies with Rheumatologic Involvement

Thrombotic microangiopathies are heterogeneous disorders characterized by microangiopathic hemolytic anemia with thrombocytopenia and renal injury. There are a variety of causes, including metabolic disorders, infections, medications, complement disorders, pregnancy, malignancy, and autoimmune disorders. This review focuses on renal thrombotic microangiopathy in the setting of rheumatologic diseases. Systemic lupus erythematosus is the most common autoimmune disease associated with thrombotic microangiopathy. Other etiologies include scleroderma renal crisis and antiphospholipid antibody syndrome, which can be primary or secondary to autoimmune diseases including systemic lupus erythematosus. There have also been case reports of thrombotic microangiopathy in the setting of rheumatoid arthritis and dermatomyositis.

T and NK Cell Phenotypic Abnormalities in Systemic Sclerosis: a Cohort Study and a Comprehensive Literature Review

Scleroderma (SSc) is a rare and heterogeneous immune-mediated disease involving the connective tissue and microvasculature whose pathogenesis remains unclear. Data concerning T and natural killer (NK) cell abnormalities and cytokine levels in the peripheral blood (PB) from patients with SSc are scarce, and the results are contradictory. The present study aimed to analyze the changes of T lymphocytes, NK cells, and T helper (Th)-related cytokines in the PB of patients with SSc in comparison to healthy individuals and its relation to disease subtype and stage, organ involvement, and nailfold capillaroscopic changes. A non-random convenience sample of 57 scleroderma patients was utilized. Fifty-five out of the 57 patients studied were women (97 %); 10 patients presented pre-scleroderma (pre-SSc) and 47 SSc: 34 limited cutaneous SSc (lcSSc) and 13 diffuse cutaneous SSc (dcSSc). Patients with SSc were classified in early (n = 7), intermediate (n = 10), and late (n = 30) disease. Blood samples were analyzed by flow cytometry for total T cells, CD4+ and CD8+ T cell subsets, total NK cells, and CD56+low and CD56+high NK cell subsets. T cells were further analyzed for the expression of the CD56 adhesion molecule and activation-related markers (HLA-DR, CD45RO). In addition, the serum levels of Th1-, Th2-, and Th17-related cytokines were measured by flow cytometry. Twenty-five healthy individuals recruited from the blood bank were used as controls. Patients had lower numbers of total lymphocytes and T cells comparing to healthy controls. Both CD4+ and CD8+ T cells were decreased, but differences were statistically significant only for CD8+ and CD8+ CD45RO+ T cells. These alterations were seen in patients with SSc but not in patients with pre-SSc, and, in general, they were more pronounced in patients with dcSSc than in patients with lcSSc, in patients with vascular involvement than in those without, as well as in patients having active and late nailfold capillaroscopic patterns. CD56+ T cells were also decreased in SSc patients, especially in those with active/late capillaroscopic patterns or with severe lung disease. Diminished numbers of circulating NK cells were also observed in patients with lcSSc and in those with early disease. No statistically significant changes were found in serum cytokine levels, as compared with controls. Patients with SSc had major alterations in circulating CD8+ and CD56+ T cells, as well as in NK cells, suggesting that these cells may play a relevant role in SSc pathogenesis, probably operating at different phases and/or at different organs. In addition, the serum levels of Th1, Th2, and Th17 cytokines did not provide useful information for evaluating T cell polarization in SSc.

Evaluating Choroidal Characteristics in Systemic Sclerosis Using Enhanced Depth Imaging Optical Coherence Tomography

PURPOSE

To evaluate choroidal thickness (CT) and investigate the involvement of choroidal circulation in patients with systemic sclerosis (SSc).

METHODS

A total of 120 eyes of 60 SSc patients and 60 eyes of 30 healthy controls were evaluated. CT measurements were performed at the subfoveal region, 1000 µm nasal and 1000 µm temporal to the fovea, using enhanced depth imaging optical coherence tomography. CT measurements were compared between the patients and controls.

RESULTS

The average subfoveal, parafoveal nasal and parafoveal temporal CT were significantly thinner in SSc patients when compared with healthy controls (297.77 ± 60.8 µm vs 339.8 ± 50.4 µm; 267.32 ± 51.1 µm vs 308.65 ± 49.9 µm; 270.63 ± 46.3 µm vs 309.22 ± 42.4 µm, respectively; p<0.001 for all).

CONCLUSIONS

Reduced CT in SSc patients supports the hypothesis of widespread vascular injury, including the ocular microcirculation.

Pathogenesis of Systemic Sclerosis

Systemic scleroderma (SSc) is one of the most complex systemic autoimmune diseases. It targets the vasculature, connective tissue-producing cells (namely fibroblasts/myofibroblasts), and components of the innate and adaptive immune systems. Clinical and pathologic manifestations of SSc are the result of: (1) innate/adaptive immune system abnormalities leading to production of autoantibodies and cell-mediated autoimmunity, (2) microvascular endothelial cell/small vessel fibroproliferative vasculopathy, and (3) fibroblast dysfunction generating excessive accumulation of collagen and other matrix components in skin and internal organs. All three of these processes interact and affect each other. The disease is heterogeneous in its clinical presentation that likely reflects different genetic or triggering factor (i.e., infection or environmental toxin) influences on the immune system, vasculature, and connective tissue cells. The roles played by other ubiquitous molecular entities (such as lysophospholipids, endocannabinoids, and their diverse receptors and vitamin D) in influencing the immune system, vasculature, and connective tissue cells are just beginning to be realized and studied and may provide insights into new therapeutic approaches to treat SSc.

Drug target prediction and repositioning using an integrated network-based approach

The discovery of novel drug targets is a significant challenge in drug development. Although the human genome comprises approximately 30,000 genes, proteins encoded by fewer than 400 are used as drug targets in the treatment of diseases. Therefore, novel drug targets are extremely valuable as the source for first in class drugs. On the other hand, many of the currently known drug targets are functionally pleiotropic and involved in multiple pathologies. Several of them are exploited for treating multiple diseases, which highlights the need for methods to reliably reposition drug targets to new indications. Network-based methods have been successfully applied to prioritize novel disease-associated genes. In recent years, several such algorithms have been developed, some focusing on local network properties only, and others taking the complete network topology into account. Common to all approaches is the understanding that novel disease-associated candidates are in close overall proximity to known disease genes. However, the relevance of these methods to the prediction of novel drug targets has not yet been assessed. Here, we present a network-based approach for the prediction of drug targets for a given disease. The method allows both repositioning drug targets known for other diseases to the given disease and the prediction of unexploited drug targets which are not used for treatment of any disease. Our approach takes as input a disease gene expression signature and a high-quality interaction network and outputs a prioritized list of drug targets. We demonstrate the high performance of our method and highlight the usefulness of the predictions in three case studies. We present novel drug targets for scleroderma and different types of cancer with their underlying biological processes. Furthermore, we demonstrate the ability of our method to identify non-suspected repositioning candidates using diabetes type 1 as an example.

Applications of polymeric adjuvants in studying autoimmune responses and vaccination against infectious diseases

Polymers as an adjuvant are capable of enhancing the vaccine potential against various infectious diseases and also are being used to study the actual autoimmune responses using self-antigen(s) without involving any major immune deviation. Several natural polysaccharides and their derivatives originating from microbes and plants have been tested for their adjuvant potential. Similarly, numerous synthetic polymers including polyelectrolytes, polyesters, polyanhydrides, non-ionic block copolymers and external stimuli responsive polymers have demonstrated adjuvant capacity using different antigens. Adjuvant potential of these polymers mainly depends on their solubility, molecular weight, degree of branching and the conformation of polymeric backbone. These polymers have the ability not only to activate humoral but also cellular immune responses in the host. The depot effect, which involves slow release of antigen over a long duration of time, using different forms (particulate, solution and gel) of polymers, and enhances the co-stimulatory signals for optimal immune activation, is the underlying principle of their adjuvant properties. Possibly, polymers may also interact and activate various toll-like receptors and inflammasomes, thus involving several innate immune system players in the ensuing immune response. Biocompatibility, biodegradability, easy production and purification, and non-toxic properties of most of the polymers make them attractive candidates for substituting conventional adjuvants that have undesirable effects in the host.

Mapping QTL affecting a systemic sclerosis-like disorder in a cross between UCD-200 and red jungle fowl chickens

Systemic sclerosis (SSc) or scleroderma is a rare, autoimmune, multi-factorial disease characterized by early microvascular alterations, inflammation, and fibrosis. Chickens from the UCD-200 line develop a hereditary SSc-like disease, showing all the hallmarks of the human disorder, which makes this line a promising model to study genetic factors underlying the disease. A backcross was generated between UCD-200 chickens and its wild ancestor - the red jungle fowl and a genome-scan was performed to identify loci affecting early (21 days of age) and late (175 days of age) ischemic lesions of the comb. A significant difference in frequency of disease was observed between sexes in the BC population, where the homogametic males were more affected than females, and there was evidence for a protective W chromosome effect. Three suggestive disease predisposing loci were mapped to chromosomes 2, 12 and 14. Three orthologues of genes implicated in human SSc are located in the QTL region on chromosome 2, TGFRB1, EXOC2-IRF4 and COL1A2, as well as CCR8, which is more generally related to immune function. IGFBP3 is also located within the QTL on chromosome 2 and earlier studies have showed increased IGFBP3 serum levels in SSc patients. To our knowledge, this study is the first to reveal a potential genetic association between IGFBP3 and SSc. Another gene with an immunological function, SOCS1, is located in the QTL region on chromosome 14. These results illustrate the usefulness of the UCD-200 chicken as a model of human SSc and motivate further in-depth functional studies of the implicated candidate genes.

Annual Medical Costs and Healthcare Resource Use in Patients with Systemic Sclerosis in an Insured Population

Objective.

Systemic sclerosis (SSc) is a chronic autoimmune disease. The objective of our study was to estimate the medical costs and healthcare resource use of subjects with SSc in a large US managed care plan.

Methods.

Subjects at least 18 years of age and with claims-based evidence of SSc (ICD-9-CM code 710.1x) were identified from a health plan database from 2003 through 2008. Subjects were matched to unaffected controls, based on index date, age, sex, geographic region, time on insurance, and comorbidity score. Costs and resource use were identified during the 12-month postindex period. A generalized linear model (GLM) was used to estimate costs, controlling for demographic and clinical characteristics.

Results.

In this study, 1648 subjects with SSc were matched to 4944 controls. Mean overall annual medical costs were higher among SSc subjects than controls ($17,365 vs $5,508; p < 0.001). A GLM model supported these results. Evidence of lung disease, gastrointestinal bleeding, or renal disease increased costs (all p < 0.001). Compared to controls, significantly higher proportions of SSc subjects had postindex ambulatory visits, emergency department visits, and inpatient hospital stays (all p < 0.001).

Conclusion.

Our findings suggest that the medical costs and resource use associated with treating SSc are high (compared to matched controls), and as expected, subjects with serious disease complications experience the highest costs.

Serum leptin, resistin and TNF-α levels in patients with systemic sclerosis: the role of adipokines in scleroderma

AIM

Systemic sclerosis (SSc) is a chronic fibrotic collagen tissue disease. Leptin's role in regulating immune and inflammatory response has become increasingly evident. Resistin has pro-inflammatory properties and also is associated with inflammatory markers in some rheumatologic diseases. The purpose of this study was to determine serum leptin, resistin and tumor necrosis factor alpha (TNF-α) in SSc patients and evaluate their association with other frequently used laboratory and clinic findings.

METHOD

Sixteen patients were compared with 30 healthy women of similar age and body mass index. Serum leptin, resistin and TNF-α levels were measured by enzyme-linked immunosorbent assay and results were assessed by Mann-Whitney U -test and Spearman's correlation test.

RESULTS

Leptin levels were significantly increased in the SSc group compared to controls (7789.43 ± 1180.72 pg/mL, 1790.55 ± 333.68 pg/mL, P < 0.0001). TNF-α was significantly elevated in patients and it was also positively correlated with leptin (25.30 ± 2.16 pg/mL, 20.95 ± 0.30 pg/mL, P = 0.001), (P = 0.002, r = 0.523). There was no association between leptin, resistin, TNF-α levels and skin score, activity score and disease duration in the SSc patients (P > 0.05).

CONCLUSION

Leptin, resistin and TNF-α levels were found to be higher in SSc in contrast to the control group. These adipokines may have differentiating roles in the pathogenesis of SSc. In order to verify these findings, further clinical studies are needed with larger patient groups.

Fibrosis in systemic sclerosis: common and unique pathobiology

Fibrosis in systemic sclerosis (SSc), a complex polygenic disease associated with autoimmunity and proliferative/obliterative vasculopathy, shares pathobiologic features in common with other fibrosing illnesses, but also has distinguishing characteristics. Fibroblast activation induced by transforming growth factor-β (TGF-β), Wnts and innate immune receptors, along with oxidative stress and reactive oxygen species (ROS) are implicated in pathogenesis. On the other hand, the roles of endothelial-mesenchymal differentiation and bone marrow-derived fibrocytes remain to be established. Fibrotic responses are modulated by transcriptional activators and cofactors, epigenetic factors, and microRNAs that can amplify or inhibit ligand-induced signaling. The nuclear orphan receptor PPAR-γ appears to be important in governing the duration and intensity of fibroblast activation and mesenchymal progenitor cell differentiation, and defects in PPAR-γ expression or function in SSc may underlie the uncontrolled progression of fibrosis. Identifying the perturbations in signaling pathways and cellular differentiation programs responsible for tissue damage and fibrosis in SSc allows their selective targeting using novel compounds, or by innovative uses of already-approved drugs (drug repurposing).

Silicone and scleroderma revisited

Silicone, a synthetic polymer considered to be a biologically inert substance, is used in a multitude of medical products, the most publicly recognized of which are breast implants. Silicone breast implants have been in use since the early 1960s for cosmetic and reconstructive purposes, and reports of autoimmune disease-like syndromes began appearing in the medical literature soon thereafter. Over the previous year, silicone implants have been suggested as playing a role in a new syndrome that encompasses a wide array of immune-related manifestations, termed ASIA ('Autoimmune Syndrome Induced by Adjuvant'). Scleroderma, a relatively rare connective tissue disease with skin manifestations and systemic effects, has also been described in association with silicone implantation and rupture. However, epidemiological studies and meta-analyses have failed to corroborate the clinical impression of silicone-induced scleroderma. The following review describes the mechanisms by which silicone may mediate autoimmunity in general, as well as the evidence for causal associations with more specific autoimmune syndromes in general, and scleroderma in particular.

Epidemiology of systemic sclerosis in a large US managed care population

OBJECTIVE

To estimate the incidence and prevalence of systemic sclerosis (SSc) in a large US managed care organization (MCO) database.

METHODS

Subjects with claims-based evidence of SSc (ICD-9-CM code 710.1x) were identified from a health plan database. Incidence and prevalence for the period 2003-2008 were calculated.

RESULTS

The overall age- and sex-adjusted incidence rate (2003-2008) for SSc was 5.6 cases per 100,000 person-years. The annual prevalence of SSc ranged from 13.5 in 2003 to 18.4 (per 100,000) in 2008.

CONCLUSION

This analysis suggests a higher incidence and lower prevalence of SSc in this MCO than those previously reported for the United States.

Increased frequency of circulating Th22 in addition to Th17 and Th2 lymphocytes in systemic sclerosis: association with interstitial lung disease

INTRODUCTION

T cell abnormalities have been associated with the pathogenesis of systemic sclerosis (SSc). Recently, besides T helper (Th)17 cells, the Th22 subset has been identified in humans. Our purpose was to investigate the pattern of cytokines produced and chemokine-receptors expressed by peripheral blood (PB) Th cells in SSc and healthy donors (HD) focusing on cells producing interleukin (IL)-17 and IL-22 and to identify specific clinical associations.

METHODS

Clinical data and peripheral blood were collected in 33 SSc individuals and 29 HD. IL-17A, IL-22, interferon gamma (IFN-γ), IL-4 production, the chemokine receptors CCR4, CCR6, CCR10, CXCR3 expression and the CD161 Th17 cell marker were assessed by multiparametric flow cytometry in PB CD4+ T cells. Intracellular cytokine accumulation was further investigated in CD4+ T cells expanded in vitro for seven days.

RESULTS

The frequency of Th22, Th17, Th2, but not Th1 cells, was significantly increased in SSc individuals compared to HD. The percentage of CD161+CD4+ T cells was increased in SSc and correlated with the percentage of IL-17A producing cells. Moreover, the expression of the skin- and lung-homing chemokine receptor CCR6 correlated with the frequency of IL-22 and IL-17A-producing cells in SSc but not in HD. Finally, SSc interstitial lung disease (ILD) was strongly associated with higher numbers of IL-22 and, to a lesser extent, IL-17A-producing cells.

CONCLUSIONS

IL-22 and IL-17A-producing T cells with skin- and lung-homing capabilities are characteristically increased in SSc. These findings support the hypothesis that Th22, in addition to Th17 cells, may be involved in pathological processes leading to SSc. While the association between IL-22 producing cells and ILD needs to be assessed in larger cohorts of patients, the increased frequency of Th22 cells appears to be a useful novel biomarker in SSc.

Role of IL-13 in systemic sclerosis

Systemic sclerosis (SSc) has the highest fatality rate among connective tissue diseases and is characterized by vascular damage, inflammation and fibrosis. Currently, no therapy has proven effective in modifying the course of SSc, a reflection of its complex pathogenesis. T cell-derived cytokines have been implicated in the induction of fibrosis. The role of the pro-fibrotic type 2 cytokine IL-13 and its regulation appear to be important in the pathogenesis of SSc and other fibrotic disorders. Recent work has shown that dysregulated production of IL-13 by effector CD8+ T cells is critical for predisposing patients to more severe forms of cutaneous disease and that this dysregulation is associated with defects in the molecular control of IL-13 production, such as increased expression of the transcription factor GATA-3. Silencing of GATA-3 with siRNA significantly reduces IL-13 production by CD8+ T cells from patients. We review these new insights into SSc pathogenesis that will enable establishment of highly relevant biomarkers of immune dysfunction in patients predisposed to develop SSc and open new possibilities for development of more specific diagnosis and treatment.

GATA-3 up-regulation in CD8+ T cells as a biomarker of immune dysfunction in systemic sclerosis, resulting in excessive interleukin-13 production

OBJECTIVE

Despite the importance of interleukin-13 (IL-13) in systemic sclerosis (SSc) and other fibrotic diseases, its mechanisms of action are not understood. We have reported that excessive amounts of IL-13 are produced by peripheral blood effector CD8+ T cells from patients with diffuse cutaneous SSc (dcSSc). The aim of the present study was to establish the molecular basis of IL-13 dysregulation in the pathogenesis of SSc.

METHODS

Quantitative polymerase chain reaction analysis and intracellular staining were used to study the transcription factors that control naive peripheral blood CD8+ T cell differentiation into type 1 and type 2 cytokine-secreting cells. Intracellular staining revealed that GATA-3 levels in freshly isolated naive CD8+ T cells correlated with specific clinical manifestations. We therefore assessed the effects of GATA-3 inhibition on IL-13 production in CD8+ T cells from the SSc patients.

RESULTS

Freshly isolated naive peripheral blood CD8+ T cells expressed high levels of GATA-3 and failed to down-regulate IL-13 production when cultured under type 1-skewing conditions, but maintained adequate levels of interferon-γ production. Cellular GATA-3 levels were significantly higher in patients with dcSSc and early inflammatory disease. Silencing of GATA-3 with small interfering RNA significantly reduced IL-13 production by CD8+ T cells, demonstrating a causal relationship between GATA-3 and IL-13.

CONCLUSION

These results provide important new insights into SSc pathogenesis and suggest that increased GATA-3 expression in CD8+ T cells could be a highly relevant biomarker of immune dysfunction in patients with dcSSc. GATA-3 could be a novel therapeutic target for this currently incurable disease.

Database survey of anti-inflammatory plants in South America: a review

Inflammation is a complex event linked to tissue damage whether by bacteria, physical trauma, chemical, heat or any other phenomenon. This physiological response is coordinated largely by a variety of chemical mediators that are released from the epithelium, the immunocytes and nerves of the lamina propria. However, if the factor that triggers the inflammation persists, the inflammation can become relentless, leading to an intensification of the lesion. The present work is a literature survey of plant extracts from the South American continent that have been reported to show anti-inflammatory activity. This review refers to 63 bacterial families of which the following stood out: Asteraceae, Fabaceae, Euphorbiaceae, Apocynaceae and Celastraceae, with their countries, parts used, types of extract used, model bioassays, organisms tested and their activity.

Fibrosis in systemic sclerosis: emerging concepts and implications for targeted therapy

Systemic sclerosis (SSc) is a complex and incompletely understood disease associated with fibrosis in multiple organs. Recent findings identify transforming growth factor-ß (TGF-ß), Wnt ligands, toll-like receptor-mediated signaling, hypoxia, type I interferon, type 2 immune responses and mechanical stress as extracellular cues that modulate fibroblast function and differentiation, and as potential targets for therapy. Moreover, fibrillin-1 has a major role in storing and regulating the bioavailability of TGF-ß and other cytokines, and fibrillin-1 mutations are implicated in a congenital form of scleroderma called stiff skin syndrome. Fibrosis is due not only to the activation of tissue-resident fibroblasts and their transdifferentiation into myofibroblasts, but also the differentiation of bone marrow-derived fibrocytes, and transition of endothelial and epithelial cells, pericytes and adipocytes into activated mesenchymal cells. These responses are modulated by signaling mediators and microRNAs that amplify or inhibit TGF-ß and Wnt signaling. Gain-of-function and loss-of-function abnormalities of these mediators may account for the characteristic activated phenotype of SSc fibroblasts. The nuclear orphan receptor PPAR-γ plays a particularly important role in limiting the duration and intensity of fibroblast activation and differentiation, and impaired PPAR-γ expression or function in SSc may underlie the uncontrolled progression of fibrosis. Identifying the perturbations in signaling pathways, mediators and differentiation programs that are responsible for SSc tissue damage allows their selective targeting. This in turn opens the door for therapies utilizing novel compounds, or drug repurposing by innovative uses of already-approved drugs. In view of the heterogeneous clinical presentation and unpredictable course of SSc, as well as its complex pathogenesis, only robust clinical trials incorporating the judicious application of biomarkers will be able to clarify the clinical utility of these innovative approaches.

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.

Scleroderma renal crisis: a pathology perspective

Scleroderma renal crisis (SRC) is an infrequent but serious complication of systemic sclerosis (SSc). It is associated with increased vascular permeability, activation of coagulation cascade, and renin secretion, which may lead to the acute renal failure typically associated with accelerated hypertension. The histologic picture of SRC is that of a thrombotic microangiopathy process with prominent small vessel involvement manifesting as myxoid intimal changes, thrombi, onion skin lesions, and/or fibrointimal sclerosis. Renal biopsies play an important role in confirming the clinical diagnosis, excluding overlapping/superimposed diseases that might lead to acute renal failure in SSc patients, helping to predict the clinical outcome and optimizing patient management. Kidney transplantation may be the only treatment option available for a subset of SRC patients who develop end-stage renal failure despite aggressive angiotensin-converting enzyme inhibitor therapy. However, the posttransplant outcome for SSc patients is currently suboptimal compared to the general renal transplant population.

Decreased expression of caveolin 1 in patients with systemic sclerosis: crucial role in the pathogenesis of tissue fibrosis

OBJECTIVE

Recent studies have implicated caveolin 1 in the regulation of transforming growth factor beta (TGFbeta) downstream signaling. Given the crucial role of TGFbeta in the pathogenesis of systemic sclerosis (SSc), we sought to determine whether caveolin 1 is also involved in the pathogenesis of tissue fibrosis in SSc. We analyzed the expression of CAV1 in affected SSc tissues, studied the effects of lack of expression of CAV1 in vitro and in vivo, and analyzed the effects of restoration of caveolin 1 function on the fibrotic phenotype of SSc fibroblasts in vitro.

METHODS

CAV1 expression in tissues was analyzed by immunofluorescence and confocal microscopy. The extent of tissue fibrosis in Cav1-knockout mice was assessed by histologic/histochemical analyses and quantified by hydroxyproline assays. Cav1-null and SSc fibroblast phenotypes and protein production were analyzed by real-time polymerase chain reaction, immunofluorescence, Western blot, and multiplexed enzyme-linked immunosorbent assay techniques. The effects of restoration of caveolin 1 function in SSc fibroblasts in vitro were also examined using a cell-permeable recombinant CAV1 peptide.

RESULTS

CAV1 was markedly decreased in the affected lungs and skin of SSc patients. Cav1-knockout mice developed pulmonary and skin fibrosis. Down-regulation of caveolin 1 was maintained in cultured SSc fibroblasts, and restoration of caveolin 1 function in vitro normalized their phenotype and abrogated TGFbeta stimulation through inhibition of Smad3 activation.

CONCLUSION

Caveolin 1 appears to participate in the pathogenesis of tissue fibrosis in SSc. Restoration of caveolin 1 function by treatment with a cell-permeable peptide corresponding to the CAV1 scaffolding domain may be a novel therapeutic approach in SSc.

Graves' disease associated with primary systemic sclerosis

Graves' disease can be associated with other autoimmune disorders. Primary systemic sclerosis (PSS) is such a disease characterised by multi-organ fibrosis. Abnormal thyroid antibody titres and hypothyroidism as well as hyperthyroidism have been observed in PSS patients. Specific and idiopathic inflammatory disorders are an important differential diagnosis in Graves'orbitopathy (GO). Mycophenolate mofetil (MM) is an immunosuppressive drug which depletes guanosin nucleotides in proliferating B-and T-lymphocytes. We describe the effect of MM on the endocrine orbitopathy of a patient with PSS.

The immunology of fibrosis: innate and adaptive responses

Fibrosis is an important health problem, and its pathogenetic principles are still largely unknown. It can develop either spontaneously, or, more frequently, as a consequence of various underlying diseases. Irrespective of the primary cause, however, fibrotic tissue is always infiltrated by mononuclear immune cells. In most instances the reason for the attraction of these cells to fibrotic tissue and their proliferation remains to be determined; however their cytokine profile shows clear-cut proinflammatory and profibrotic characteristics. In this review, we discuss the innate and adaptive immune reactions associated with the development of fibrosis and the molecular basis of the profibrotic mechanisms taking place in systemic sclerosis (scleroderma), arteriosclerosis and peri-silicone mammary implant fibrosis.

Antifibroblast antibodies in systemic sclerosis induce fibroblasts to produce profibrotic chemokines, with partial exploitation of toll-like receptor 4

OBJECTIVE

Previous studies have revealed the presence of IgG antifibroblast antibodies (AFAs) capable of binding to the surface of fibroblasts in systemic sclerosis (SSc) sera. Since chemokines may directly or indirectly affect the development of fibrosis, this study was undertaken to investigate the production of chemokines induced by AFAs in fibroblasts, and to characterize the signaling pathways and surface molecules involved.

METHODS

AFA-positive and AFA-negative IgG were tested on fibroblasts. Chemokine messenger RNA expression was screened by microarray and quantitative reverse transcription-polymerase chain reaction. Production of CCL2, CXCL8, and CXCL10 proteins was assessed by enzyme-linked immunosorbent assay. Pharmacologic inhibitors were used to study signal transduction, with results assessed by Western blotting and immunofluorescence analysis. Fibroblasts with defective expression of Toll-like receptors (TLRs) and anti-TLR monoclonal antibodies (mAb) were used to assess AFA specificity.

RESULTS

In human fibroblasts, AFA-positive IgG induced the preferential transcription of chemokines with profibrotic and proangiogenic potential, including, but not exclusively, CCL2, CXCL1, CXCL8, CKLF, and ECGF1, which were distinctly different from those induced by interferon-gamma. Levels of CCL2 and CXCL8 proteins were increased in AFA-stimulated fibroblast culture supernatants. AFA binding to fibroblasts resulted in concomitant activation of ERK-1/2, c-Jun, and NF-kappaB. CCL2 production was sensitive to inhibition of both proteasome and JNK, while CXCL8 production was sensitive only to inhibition of proteasome. AFAs failed to up-regulate CCL2 expression in TLR-4-deficient fibroblasts but not in TLR-6- or TLR-2-deficient fibroblasts. Moreover, anti-TLR-4 mAb, but not anti-TLR-2 mAb, partially inhibited the production of CCL2 induced by AFAs in human fibroblasts.

CONCLUSION

Autoantibodies that bind to the surface of fibroblasts may contribute to the pathogenesis of SSc by up-regulating the fibroblast production of profibrotic and proangiogenic chemokines, in a proteasome- and TLR-4-dependent manner.

The constituents of Anisomeles indica and their anti-inflammatory activities

ETHNOPHARMACOLOGICAL RELEVANCE

Anisomeles indica (L.) Kuntze. (Labiatae), popularly known as 'yu-chen-tsao', has been traditionally used as anti-inflammatory agent.

AIM OF THE STUDY

Investigate the chemical constituents from the whole plants of Anisomeles indica, and evaluate their in vitro anti-inflammatory activities.

RESULTS

The combined MeOH extract was successively partitioned with CHCl(3) and n-butanol, then submitted to several column chromatographic, and HPLC purification procedures which led to the isolation of one cembrane-type diterpenoid (3), two benzenoids (4 and 5), five flavonoids (1, 2, 6, 7 and 14), and six phenyl propanoids (8-13). The compounds 1-14 were examined for their inhibitory effects on inflammatory mediator's enhanced production from LPS/IFN-gamma-stimulated macrophages. Among these, ovatodiolide (3) exhibited potent inhibition on NO, TNF-alpha and IL-12 enhanced production at a concentration of 5 microM, followed by pedalitin (1), scutellarein 7-O-beta-d-glucuronide methyl ester (6), and acteoside (12) at 40 microM (P<0.05). Furthermore, 2 microM of 3, and 20 microM of 1 and 6 significantly (P<0.05) arrested the cell cycle of Con A-stimulated spleen cells at the G0/G1 stage.

CONCLUSION

This is the first report on the presence of compounds 1 and 4-13 in this plant and of the potent anti-inflammatory activity of 1, 3, 6 and 12 in vitro. These compounds may account for the use of Anisomeles indica in folk medicine to treat inflammation.

T cells, B cells, and polarized immune response in the pathogenesis of fibrosis and systemic sclerosis

PURPOSE OF REVIEW

A better comprehension of the interactions between cells of the adaptive immune system with fibroblasts and endothelial cells is required to understand abnormal extracellular matrix deposition, development of pathologic fibrosis, and vasculopathy.

RECENT FINDINGS

Skin T cells with high IL-4 production potential and peripheral blood T cells preferentially expressing chemokine receptors associated with Th2 functions are found in individuals with active systemic sclerosis. Animal models indicate that Th2 cells and IL-13 can induce muscular hypertrophy in pulmonary arterial vasculature. In bleomycin-induced fibrosis, B cells produce fibrogenic cytokines upon interaction of an endogenous ligand (hyaluronan) with toll-like receptor-4. In the sclerodermatous graft versus host model, the lack of tumor necrosis factor-production by CD4+ T cells is permissive for fibrosis development. Dermal fibrosis and capillary loss typical of systemic sclerosis can be reversible after high-dose immunosuppression and hematopoietic stem cell transplantation.

SUMMARY

Although immunosuppressive strategies to treat patients with systemic sclerosis and allied conditions are largely disappointing, thus indicating a permissive rather than causative role of immunoinflammatory events characteristic of the disease, new findings stress that cells of the adaptive immune system play important roles in assisting fibrogenesis and vascular abnormalities. This may help in identifying efficacious strategies aimed at their control.

In vivo investigations on anti-fibrotic potential of proteasome inhibition in lung and skin fibrosis

In systemic sclerosis (SSc), a disease characterized by fibrosis of the skin and internal organs, the occurrence of interstitial lung disease is responsible for high morbidity and mortality. We previously demonstrated that proteasome inhibitors (PI) show anti-fibrotic properties in vitro by reducing collagen production and favoring collagen degradation in a c-jun N-terminal kinase (JNK)-dependent manner in human fibroblasts. Therefore, we tested whether PI could control fibrosis development in bleomycin-induced lung injury, which is preceded by massive inflammation. We extended the study to test PI in TSK-1/+ mice, where skin fibrosis develops in the absence of overt inflammation. C57Bl/6 mice received bleomycin intratracheally and were treated or not with PI. Lung inflammation and fibrosis were assessed by histology and quantification of hydroxyproline content, type I collagen mRNA, and TGF-beta at Days 7, 15, and 21, respectively. Histology was used to detect skin fibrosis in TSK-1/+mice. The chymotryptic activity of 20S proteasome was assessed in mice blood. JNK and Smad2 phosphorylation were evaluated by Western blot on lung protein extracts. PI reduced collagen mRNA levels in murine lung fibroblasts, without affecting their viability in vitro. In addition, PI inhibited the chymotryptic activity of proteasome and enhanced JNK and TGF-beta signaling in vivo. PI failed to prevent bleomycin-induced lung inflammation and fibrosis and to attenuate skin fibrosis in TSK-1/+mice. In conclusion, our results provide direct evidence that, despite promising in vitro results, proteasome blockade may not be a strategy easily applicable to control fibrosis development in diseases such as lung fibrosis and scleroderma.

Molecular pathways as novel therapeutic targets in systemic sclerosis

PURPOSE OF REVIEW

Systemic sclerosis is a complex disease characterized by immune/inflammatory, vascular and fibrotic processes. To date, no treatment has proven effective in modifying the course of the disease. Recent studies have begun to yield insights into the nature and interrelationship among these processes, and their cellular and molecular components.

RECENT FINDINGS

Novel intracellular molecular pathways have been characterized that positively or negatively regulate fibroblast responses contributing to the process of fibrosis. These include signaling mediators that specify and amplify transforming growth factor-beta responses, or inhibit collagen stimulation and block these responses in vitro and in animal models. Various gain of function or loss of function abnormalities in these mediators have been identified in systemic sclerosis, and may account for the characteristic activated phenotype of systemic sclerosis fibroblasts.

SUMMARY

The identification of novel signaling pathways and mediators that are altered in systemic sclerosis and contribute to tissue damage allows their selective targeting. This in turn opens the door for novel therapeutic strategies utilizing novel compounds, or innovative ways of using already-approved drugs. In light of the complex pathogenesis of systemic sclerosis, however, only carefully designed clinical trials with appropriate biomarkers and outcome measures will be able to clarify the clinical utility of these innovative approaches.

T cells expressing allograft inflammatory factor 1 display increased chemotaxis and induce a profibrotic phenotype in normal fibroblasts in vitro

OBJECTIVE

Allograft inflammatory factor 1 (AIF-1) was first identified in rat cardiac allografts undergoing chronic rejection. The vasculopathy of chronic allograft rejection is strikingly similar to that seen in patients with systemic sclerosis (SSc). We previously demonstrated AIF-1 expression in inflammatory cells infiltrating skin and lungs from SSc patients, but its role in SSc pathogenesis is unknown. The present study was undertaken to investigate the effects of AIF-1 on T cell migration and production of cytokines capable of modulating normal dermal fibroblast functions.

METHODS

Stably transfected Jurkat T cells expressing 2 AIF-1 splicing variants were prepared, and their migration toward fibroblast monolayers assayed in Transwell cultures. Cytokine production was assessed by real-time polymerase chain reaction (PCR) and multiplex enzyme-linked immunosorbent assay. Fibroblast gene expression was quantified by real-time PCR, and collagen production by Western blot analysis of culture media.

RESULTS

AIF-1 significantly increased Jurkat T cell migration toward fibroblast monolayers. Expression of AIF-1 isoform 2 in Jurkat T cells up-regulated their production of interleukin-4 (IL-4) and IL-17. Conditioned media from AIF-1-expressing clones stimulated synthesis of types I and III collagen and expression of IL-6, transforming growth factor beta, endothelin receptor, and alpha-smooth muscle actin by normal dermal fibroblasts.

CONCLUSION

These results suggest that AIF-1 may participate in the early pathogenesis of SSc by promoting tissue T cell infiltration and production of cytokines capable of inducing the expression of a fibrotic phenotype in normal fibroblasts.

[Pathogenesis of systemic sclerosis]

Systemic sclerosis is a complex multi-systemic disease with a mostly unresolved pathogenesis. Following an inflammatory reaction, overproduction of collagen and other extra-cellular matrix components leads to a characteristic fibrosis. It remains unclear why this overproduction by fibroblasts and myofibroblasts occurs. Micro-vascular disturbances and endothelial cells, as well as immunomodulation and inflammation are central factors. Besides intrinsic influences, such as genetic polymorphisms, multiple mediators with fibrotic effects such as Platelet Derived Growth Factor, Transforming Growth Factor-beta and Connective Tissue Growth Factor have been characterized. These have become targets for innovative therapeutic strategies that might lead to specific treatments for systemic sclerosis.