Dysregulated expression of MIG/CXCL9, IP-10/CXCL10 and CXCL16 and their receptors in systemic sclerosis

The Role of PPAR Gamma in Systemic Sclerosis

Fibrosis is recognized as an important feature of many chronic diseases, such as systemic sclerosis (SSc), an autoimmune disease of unknown etiology, characterized by immune dysregulation and vascular injury, followed by progressive fibrosis affecting the skin and multiple internal organs. SSc has a poor prognosis because no therapy has been shown to reverse or arrest the progression of fibrosis, representing a major unmet medical need. Recently, antifibrotic effects of PPARγ ligands have been studied in vitro and in vivo and some theories have emerged leading to new insights. Aberrant PPARγ function seems to be implicated in pathological fibrosis in the skin and lungs. This antifibrotic effect is mainly related to the inhibition of TGF-β/Smad signal transduction but other pathways can be involved. This review focused on recent studies that identified PPARγ as an important novel pathway with critical roles in regulating connective tissue homeostasis, with emphasis on skin and lung fibrosis and its role on systemic sclerosis.

Vascular biomarkers and correlation with peripheral vasculopathy in systemic sclerosis

Vascular disease is a hallmark of systemic sclerosis (SSc). It is present in every patient, being responsible both for the earliest clinical manifestations and the major life-threatening complications of the disease, and thus determining important morbidity and mortality. In SSc, progressive vascular injury leads to vascular tone dysfunction and reduced capillary blood flow, with consequent tissue ischemia and chronic hypoxia. These phenomena are often accompanied by abnormal levels of vascular factors. Microangiopathy in SSc may be easily assessed by nailfold videocapillaroscopy. The variety of derangements detected in the nailfold capillaries is accompanied by abnormal levels of different vascular mediators and appears to be the best evaluable predictor of the development of peripheral vascular complications, such as digital ulcers. The purpose of this review is to summarize in SSc the most relevant vascular biomarkers and the main associations between vascular biomarkers and capillaroscopic parameters and/or the presence of digital ulcers. Vascular biomarkers could become useful predictive factors of vascular damage in SSc, allowing an earlier management of vascular complications.

Interferon-gamma inducible protein-10 as a potential biomarker in localized scleroderma

Introduction

The purpose of this study was to evaluate the presence and levels of interferon-gamma inducible protein-10 (IP-10) in the plasma and skin of pediatric localized scleroderma (LS) patients compared to those of healthy pediatric controls and to determine if IP-10 levels correlate to clinical disease activity measures.

Methods

The presence of IP-10 in the plasma was analyzed using a Luminex panel in 69 pediatric patients with LS and compared to 71 healthy pediatric controls. Of these patients, five had available skin biopsy specimens with concurrent clinical and serological data during the active disease phase, which were used to analyze the presence and location of IP-10 in the skin by immunohistochemistry (IHC).

Results

IP-10 levels were significantly elevated in the plasma of LS patients compared to that of healthy controls and correlated to clinical disease activity measures in LS. Immunohistochemistry staining of IP-10 was present in the dermal infiltrate of LS patients and was similar to that found in psoriasis skin specimens, the positive disease control.

Conclusions

Elevation of IP-10 levels in the plasma compared to those of healthy controls and the presence of IP-10 staining in the affected skin of LS patients indicates that IP-10 is a potential biomarker in LS. Furthermore, significant elevation of IP-10 in LS patients with active versus inactive disease and correlations between IP-10 levels and standardized disease outcome measures of activity in LS strongly suggest that IP-10 may be a biomarker for disease activity in LS.

Role of CXCR3/CXCL10 axis in immune cell recruitment into the small intestine in celiac disease

Lymphocytic infiltration in the lamina propria (LP), which is primarily composed of CD4⁺ Th1 cells and plasma cells, and increased numbers of intraepithelial lymphocytes (IELs), is a characteristic finding in active celiac disease (CD). Signals for this selective cell recruitment have not been fully established. CXCR3 and its ligands, particularly CXCL10, have been suggested to be one of the most relevant pathways in the attraction of cells into inflamed tissues. In addition, CXCR3 is characteristically expressed by Th1 cells. The aim of this work was to investigate the participation of the chemokine CXCL10/CXCR3 axis in CD pathogenesis. A higher concentration of CXCL10 was found in the serum of untreated CD patients. The mRNA levels of CXCL10 and CXCL11 but not CXCL9 were significantly higher in duodenal biopsies from untreated CD patients compared with non-CD controls or treated patients. The results demonstrate that CXCL10 is abundantly produced in untreated CD and reduced in treated patients, and the expression of CXCL10 was found to be correlated with the IFNγ levels in the tissue. Plasma cells and enterocytes were identified as CXCL10-producing cells. Moreover, the CXCL10 expression in intestinal tissues was upregulated by poly I:C and IL-15. IELs, LP T lymphocytes, and plasma cells, which infiltrate the intestinal mucosa in untreated CD, express CXCR3. The CXCR3/CXCL10 signalling axis is overactivated in the small intestinal mucosa in untreated patients, and this finding explains the specific recruitment of the major cell populations that infiltrate the epithelium and the LP in CD.

Constitutively active chemokine CXC receptors

Chemokines are low-molecular-weight, secreted proteins that act as leukocyte-specific chemoattractants. The chemokine family has more than 40 members. Based on the position of two conserved cysteines in the N-terminal domain, chemokines can be divided into the CXC, C, CC, and CX3C subfamilies. The interaction of chemokines with their receptors mediates signaling pathways that play critical roles in cell migration, differentiation, and proliferation. The receptors for chemokines are G protein-coupled receptors (GPCRs), and thus far, seven CXC receptors have been cloned and are designated CXCR1-7. Constitutively active GPCRs are present in several human immune-mediated diseases and in tumors, and they have provided valuable information in understanding the molecular mechanism of GPCR activation. Several constitutively active CXC chemokine receptors include the V6.40A and V6.40N mutants of CXCR1; the D3.49V variant of CXCR2; the N3.35A, N3.35S, and T2.56P mutants of CXCR3; the N3.35 mutation of CXCR4; and the naturally occurring KSHV-GPCR. Here, we review the regulation of CXC chemokine receptor signaling, with a particular focus on the constitutive activation of these receptors and the implications in physiological conditions and in pathogenesis. Understanding the mechanisms behind the constitutive activation of CXC chemokine receptors may aid in pharmaceutical design and the screening of inverse agonists and allosteric modulators for the treatment of autoimmune diseases and cancers.

Chemokine (C-X-C motif) ligand (CXCL)10 in autoimmune diseases

(C-X-C motif) ligand (CXCL)10 (CXCL10) belongs to the ELR(-) CXC subfamily chemokine. CXCL10 exerts its function through binding to chemokine (C-X-C motif) receptor 3 (CXCR3), a seven trans-membrane receptor coupled to G proteins. CXCL10 and its receptor, CXCR3, appear to contribute to the pathogenesis of many autoimmune diseases, organ specific (such as type 1 diabetes, autoimmune thyroiditis, Graves' disease and ophthalmopathy), or systemic (such as rheumatoid arthritis, psoriatic arthritis, systemic lupus erythematosus, mixed cryoglobulinemia, Sjögren syndrome, or systemic sclerosis). The secretion of CXCL10 by cluster of differentiation (CD)4+, CD8+, natural killer (NK) and NK-T cells is dependent on interferon (IFN)-γ, which is itself mediated by the interleukin-12 cytokine family. Under the influence of IFN-γ, CXCL10 is secreted by several cell types including endothelial cells, fibroblasts, keratinocytes, thyrocytes, preadipocytes, etc. Determination of high level of CXCL10 in peripheral fluids is therefore a marker of host immune response, especially T helper (Th)1 orientated T-cells. In tissues, recruited Th1 lymphocytes may be responsible for enhanced IFN-γ and tumor necrosis factor-α production, which in turn stimulates CXCL10 secretion from a variety of cells, therefore creating an amplification feedback loop, and perpetuating the autoimmune process. Further studies are needed to investigate interactions between chemokines and cytokines in the pathogenesis of autoimmune diseases and to evaluate whether CXCL10 is a novel therapeutic target in various autoimmune diseases.

Global chemokine expression in systemic sclerosis (SSc): CCL19 expression correlates with vascular inflammation in SSc skin

OBJECTIVE

To characterise global chemokine expression in systemic sclerosis (SSc) skin in order to better understand the relationship between chemokine expression and vascular inflammation in this disease.

METHODS

We investigated chemokine mRNA expression in the skin through quantitative PCR analysis comparing patients with diffuse cutaneous (dcSSc) or limited cutaneous (lcSSc) disease with healthy controls. We tested correlations between the most regulated chemokines and vascular inflammation and macrophage recruitment. CCL19 expression was examined in human primary immune cells treated with innate immune activators.

RESULTS

The chemokines, CCL18, CCL19 and CXCL13, were upregulated in dcSSc skin, and CCL18 in lcSSc skin. Expression of CCL19 in dcSSc skin correlated with markers of vascular inflammation and macrophage recruitment. Immunofluorescence data showed CCL19 colocalisation with CD163 macrophages in dcSSc skin. In vitro studies on human primary cells demonstrated that CCL19 expression was induced after toll-like receptor activation of peripheral blood mononuclear cells and separated populations of CD14 monocytes.

CONCLUSIONS

CCL18, CCL19 and CXCL13-chemoattractants for macrophage and T cell recruitment-were three of six chemokines with the highest expression in dcSSc skin. Increased CCL19 expression in the skin suggests a role for CCL19 in the recruitment of immune cells to the peripheral tissue. Induction of CCL19 in macrophages but not structural cells indicates a role for skin-resident or recruited immune cells in perivascular inflammation. This study demonstrates that CCL19 is a sensitive marker for the perivascular inflammation and immune cell recruitment seen in dcSSc skin disease.

Interferon-γ promotes vascular remodeling in human microvascular endothelial cells by upregulating endothelin (ET)-1 and transforming growth factor (TGF) β2

Systemic sclerosis (SSc) is a complex disease characterized by vascular alterations, activation of the immune system and tissue fibrosis. Previous studies have implicated activation of the interferon pathways in the pathogenesis of SSc. The goal of this study was to determine whether interferon type I and/or type II could play a pathogenic role in SSc vasculopathy. Human dermal microvascular endothelial cells (HDMVECs) and fibroblasts were obtained from foreskins of healthy newborns. The RT Profiler PCR Array System was utilized to screen for EndoMT genes. Treatment with IFN-α or IFN-γ downregulated Fli1 and VE-cadherin. In contrast, IFN-α and IFN-γ exerted opposite effects on the expression of α-SMA, CTGF, ET-1, and TGFβ2, with IFN-α downregulating and IFN-γ upregulating this set of genes. Blockade of TGFβ signaling normalized IFN-γ-mediated changes in Fli1, VE-cadherin, CTGF, and ET-1 levels, whereas upregulation of α-SMA and TGFβ2 was not affected. Bosentan treatment was more effective than TGFβ blockade in reversing the actions of IFN-γ, including downregulation of α-SMA and TGFβ2, suggesting that activation of the ET-1 pathway plays a main role in the IFN-γ responses in HDMECs. IFN-γ induced expression of selected genes related to endothelial-to-mesenchymal transition (EndoMT), including Snail1, FN1, PAI1, TWIST1, STAT3, RGS2, and components of the WNT pathway. The effect of IFN-γ on EndoMT was mediated via TGFβ2 and ET-1 signaling pathways. This study demonstrates distinct effects of IFN-α and IFN-γ on the biology of vascular endothelial cells. IFN-γ may contribute to abnormal vascular remodeling and fibrogenesis in SSc, partially via induction of EndoMT.

Serum levels of chemokine (C-X-C motif) ligand 9 (CXCL9) are associated with tumor progression and treatment outcome in patients with oral cavity squamous cell carcinoma

OBJECTIVES

The aim of this cohort study was to examine the role of chemokine (C-X-C motif) ligand 9 (CXCL9) on oral cavity squamous cell carcinoma (OSCC).

METHODS

Sera from 181 OSCC patients, 231 healthy individuals, and 50 OSCC tumor samples were enrolled. CXCL9 expression in tissue samples was analyzed by quantitative real-time PCR and immunohistochemistry. CXCL9 serum concentrations were measured by enzyme-linked immunosorbent assay. Effects of CXCL9 on OSCC cell function were investigated by cell proliferation assays, trans-well migration/invasion assays, and RNA interference.

RESULTS

CXCL9 expression was significantly higher than for normal epithelium in the tissue samples. CXCL9 serum concentrations were also significantly higher in OSCC patients compared to those in healthy individuals. Serum CXCL9 levels were significantly higher in OSCC patients with higher pT status, pathological overall stages, tumor depths, and positive bone invasion (P = 0.033, 0.004, 0.041, and 0.002, respectively). Moreover, OSCC patients with higher CXCL9 levels (> 209 pg/mL, median level) before treatment had worse prognoses for overall survival and disease-specific survival (P = 0.0006 and 0.0009, respectively). Multivariate logistic regression analyses also indicated that higher CXCL9 serum levels were an independent prognostic factor for overall survival and disease-free survival (P = 0.003 and 0.004, respectively). The in vitro suppression of CXCL9 expression in SCC25 cells using specific interfering RNAs attenuated cell proliferation, migration and invasiveness.

CONCLUSIONS

Our study demonstrated that CXCL9 is associated with tumor burden and aggressiveness of OSCC tumors and serum level of this ligand may be useful as a prognostic indicator.

Cannabidiol inhibits angiogenesis by multiple mechanisms

BACKGROUND AND PURPOSE

Several studies have demonstrated anti-proliferative and pro-apoptotic actions of cannabinoids on various tumours, together with their anti-angiogenic properties. The non-psychoactive cannabinoid cannabidiol (CBD) effectively inhibits the growth of different types of tumours in vitro and in vivo and down-regulates some pro-angiogenic signals produced by glioma cells. As its anti-angiogenic properties have not been thoroughly investigated to date, and given its very favourable pharmacological and toxicological profile, here, we evaluated the ability of CBD to modulate tumour angiogenesis.

EXPERIMENTAL APPROACH

Firstly, we evaluated the effect of CBD on human umbilical vein endothelial cell (HUVEC) proliferation and viability - through [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and FACS analysis - and in vitro motility - both in a classical Boyden chamber test and in a wound-healing assay. We next investigated CBD effects on different angiogenesis-related proteins released by HUVECs, using an angiogenesis array kit and an ELISA directed at MMP2. Then we evaluated its effects on in vitro angiogenesis in treated HUVECs invading a Matrigel layer and in HUVEC spheroids embedded into collagen gels, and further characterized its effects in vivo using a Matrigel sponge model of angiogenesis in C57/BL6 mice.

KEY RESULTS

CBD induced HUVEC cytostasis without inducing apoptosis, inhibited HUVEC migration, invasion and sprouting in vitro, and angiogenesis in vivo in Matrigel sponges. These effects were associated with the down-modulation of several angiogenesis-related molecules.

CONCLUSIONS AND IMPLICATIONS

This study reveals that CBD inhibits angiogenesis by multiple mechanisms. Its dual effect on both tumour and endothelial cells supports the hypothesis that CBD has potential as an effective agent in cancer therapy.

Correlation of interferon-inducible chemokine plasma levels with disease severity in systemic sclerosis

OBJECTIVE

To measure interferon (IFN)-inducible chemokines in the plasma of patients with systemic sclerosis (SSc) and investigate whether the chemokine levels are correlated with disease severity.

METHODS

Plasma levels of the IFN-inducible chemokines IFNγ-inducible protein 10 (IP-10/CXCL10), IFN-inducible T cell α chemoattractant (I-TAC/CXCL11), and monocyte chemoattractant protein 1 (CCL2) were measured in SSc patients and examined for correlation with the IFN gene expression signature. A composite IFN-inducible chemokine score was generated for chemokines showing a correlation with the IFN gene signature (IP-10 and I-TAC), and this score was compared between 266 patients with SSc enrolled in the Genetics versus Environment in Scleroderma Outcome Study (GENISOS) cohort and 97 matched control subjects. Subsequently, the correlation between the IFN-inducible chemokine score at baseline and markers of disease severity was assessed. In addition, the course of the IFN-inducible chemokine score over time was examined.

RESULTS

The plasma IFN-inducible chemokine score correlated with the IFN gene expression signature, and this score was higher in SSc patients compared to controls. The IFN-inducible chemokine score was also associated with the absence of anti-RNA polymerase III antibodies and presence of anti-U1 RNP antibodies, but not with disease duration, disease type, or other autoantibodies. The chemokine score correlated with concomitantly obtained scores on the Medsger Severity Index for muscle, skin, and lung involvement in SSc, as well as the forced vital capacity, diffusing capacity for carbon monoxide, and creatine kinase levels. The association of the chemokine score with disease severity was independent of the presence of anti-U1 RNP or other potential confounders (age, sex, ethnicity, disease duration, and treatment with immunosuppressive agents). Finally, there was not a significant change in the IFN-inducible chemokine score over time.

CONCLUSION

The IFN-inducible chemokine score is a stable serologic marker of a more severe form of SSc and may be useful for risk stratification of patients, regardless of disease type (limited or diffuse) or duration of disease.

ADAM-10 is overexpressed in rheumatoid arthritis synovial tissue and mediates angiogenesis

OBJECTIVE

To examine the expression of ADAM-10 in rheumatoid arthritis (RA) synovial tissue (ST) and the role it plays in angiogenesis.

METHODS

ADAM-10 expression was determined using immunohistology, Western blotting, and quantitative polymerase chain reaction. In order to examine the role of ADAM-10 in angiogenesis, we performed in vitro Matrigel tube formation and chemotaxis assays using human microvascular endothelial cells (HMVECs) transfected with control or ADAM-10 small interfering RNA (siRNA). To determine whether ADAM-10 plays a role in angiogenesis in the context of RA, we performed Matrigel assays using a coculture system of HMVECs and RA synovial fibroblasts.

RESULTS

Endothelial cells and lining cells within RA ST expressed high levels of ADAM-10 compared with cells within osteoarthritis ST and normal ST. ADAM-10 expression was significantly elevated at the protein and messenger RNA levels in HMVECs and RA synovial fibroblasts stimulated with proinflammatory mediators compared with unstimulated cells. ADAM-10 siRNA-treated HMVECs had decreased endothelial cell tube formation and migration compared with control siRNA-treated HMVECs. In addition, ADAM-10 siRNA-treated HMVECs from the RA synovial fibroblast coculture system had decreased endothelial cell tube formation compared with control siRNA-treated HMVECs.

CONCLUSION

These data show that ADAM-10 is overexpressed in RA and suggest that ADAM-10 may play a role in RA angiogenesis. ADAM-10 may be a potential therapeutic target in inflammatory angiogenic diseases such as RA.

Serum chemokine levels as prognostic markers in patients with early systemic sclerosis: a multicenter, prospective, observational study

OBJECTIVE

To assess the utility of serum chemokine levels as a prognostic indicator of disease progression in systemic sclerosis (SSc) patients with early onset disease.

METHODS

Seventy Japanese patients with early onset SSc presenting with diffuse skin sclerosis and/or interstitial lung disease were registered in a multicenter, observational study. Concentrations of CCL2, CCL5, CXCL8, CXCL9, and CXCL10 in serum samples from all patients were measured using cytometric beads array. In 33 patients, chemokine levels were measured each year for 4 years. The ability of baseline chemokine levels to predict changes in clinical features were evaluated statistically by multiple regression analysis.

RESULTS

At their first visit, serum levels of CCL2, CCL5, CXCL8, CXCL9, and CXCL10 were significantly elevated in patients with SSc compared with healthy controls. There were significant associations between CCL2 and CXCL8 levels and between CXCL9 and CXCL10 levels in patients. The initial serum CXCL8 levels were significantly associated with the HAQ-DI at the fourth year while the %VC of baseline tended to be negatively associated with HAQ-DI at the fourth year. Initial chemokine levels were not associated with other clinical features including skin thickness score and the respiratory function.

CONCLUSION

Serum CXCL8 level may serve as a prognostic indicator of the physical dysfunction in SSc. Further longitudinal studies of larger populations are needed to confirm these findings.

Chemokines in tissue fibrosis

Fibrosis or scarring of diverse organs and tissues is considered as a pathologic consequence of a chronically altered wound healing response which is tightly linked to inflammation and angiogenesis. The recruitment of immune cells, local proliferation of fibroblasts and the consecutive accumulation of extracellular matrix proteins are common pathophysiological hallmarks of tissue fibrosis, irrespective of the organ involved. Chemokines, a family of chemotactic cytokines, appear to be central mediators of the initiation as well as progression of these biological processes. Traditionally chemokines have only been considered to play a critical role in orchestrating the influx of immune cells to sites of tissue injury. However, within the last years, further aspects of chemokine biology including fibroblast activation and angiogenesis have been deciphered in tissue fibrosis of many different organs. Interestingly, certain chemokines appear to mediate common effects in liver, kidney, lung, and skin of various animal models, while others mediate tissue specific effects. These aspects have to be kept in mind when extrapolating data of animal studies to early human trials. Nevertheless, the further understanding of chemokine effects in tissue fibrosis might be an attractive approach for identifying novel therapeutic targets in chronic organ damage associated with high morbidity and mortality. This article is part of a Special Issue entitled: Fibrosis: Translation of basic research to human disease.

Cys-X-Cys ligand 9 might be an immunological factor in the pathogenesis of oral submucous fibrosis and its concomitant oral lichenoid lesion

OBJECTIVES

Oral submucous fibrosis (OSF) is a chronic oral precancerous disease primarily caused by betel quid chewing. Some OSF patients are concomitant with oral lichenoid lesion (OLL), a white-streak lesion with a higher risk for cancerization, in OSF mucosa. Immunological reaction has been considered as one of their common pathogenic mechanisms. Cys-X-Cys ligand 9 (CXCL9) is an important factor to recruit effector neutrophils and lymphocytes in immunological reactions. However, the expression levels of CXCL9 in OSF and OLL remain unclear.

MATERIALS AND METHODS

We investigated the expression levels of CXCL9 in 10 normal buccal mucosa (NBM) samples and 56 OSF concomitant with OLL patients, and evaluated the possible mechanism of CXCL9 on their pathogenesis.

RESULTS

Our results showed NBM demonstrated negative CXCL9 expression. OSF stained positive CXCL9 mainly in the cytoplasm of inflammatory cells and endothelial cells throughout the superficial layer of connective tissue, while its concomitant OLL showed much stronger CXCL9 in all mononuclear cells of subepithelial inflammatory infiltration (p = 0.0006). There was an upregulated trend of CXCL9 expression from NBM to OSF to OLL. However, no significant association between CXCL9 expression and clinicopathologic parameters of patients was found.

CONCLUSIONS

In conclusion, CXCL9 was found for the first time to contribute to the immunological pathogenesis for both OSF and its concomitant OLL, indicating a continuously enhanced intensity of immunoreactivity in their pathogenic process.

CLINICAL RELEVANCE

CXCL9 might be a useful tool to monitor the phase and disease severity of OSF and OLL, and a potential target for further clinical therapy for both lesions.

Potential immunologic targets for treating fibrosis in systemic sclerosis: a review focused on leukocytes and cytokines

OBJECTIVES

Systemic sclerosis (SSc) is a connective tissue disease characterized by tissue fibrosis. Although the pathogenesis remains unclear, a variety of cells contribute to the fibrotic process via interactions with each other and production of various cytokines. Recent literature related to the immunologic pathogenesis and future strategies for treating the fibrosis of SSc are discussed and, especially, this literature-based review that includes the authors' perspective, focused on leukocytes and cytokines.

METHODS

A PubMed search for articles published between January 2005 and January 2012 was conducted using the following keywords: systemic sclerosis, leukocyte, cytokine, growth factor, and chemokine. The reference lists of identified articles were searched for further articles.

RESULTS

Targeting profibrogenic cytokines, including transforming growth factor-β, is still a very active area of research in SSc and most cellular studies have focused on the roles of fibroblasts in SSc. However, a growing number of recent studies indicate a role for B cells in the development of SSc and other autoimmune diseases such as systemic lupus erythematosus. Therefore, B-cell-targeted therapies, including currently available monoclonal antibodies against CD19, CD20, CD22, and B-cell-activating factor, belonging to the tumor necrosis factor family represent possible treatment options. Furthermore, the modulation of T-cell costimulatory molecules such as a recombinant fusion protein of cytotoxic T-lymphocyte antigen-4 may be as effective in SSc as it is in treating other autoimmune diseases. Approaches to antagonize interleukin (IL)-1, IL-6, or IL-17A signaling may also be attractive.

CONCLUSIONS

This review describes recent advances in the treatment of fibrosis in SSc patients focused on immunologic strategies, such as leukocyte- or cytokine-targeted therapies.