Pharmacological Stimulation of Soluble Guanylate Cyclase Counteracts the Profibrotic Activation of Human Conjunctival Fibroblasts.

Conjunctival fibrosis is a serious clinical concern implicated in a wide spectrum of eye diseases, including outcomes of surgery for pterygium and glaucoma. It is mainly driven by chronic inflammation that stimulates conjunctival fibroblasts to differentiate into myofibroblasts over time, leading to abnormal wound healing and scar formation. Soluble guanylate cyclase (sGC) stimulation was found to suppress transforming growth factor ß (TGFß)-induced myofibroblastic differentiation in various stromal cells such as skin and pulmonary fibroblasts, as well as corneal keratocytes. Here, we evaluated the in vitro effects of stimulation of the sGC enzyme with the cell-permeable pyrazolopyridinylpyrimidine compound BAY 41-2272 in modulating the TGFß1-mediated profibrotic activation of human conjunctival fibroblasts. Cells were pretreated with the sGC stimulator before challenging with recombinant human TGFß1, and subsequently assayed for viability, proliferation, migration, invasiveness, myofibroblast marker expression, and contractile properties. Stimulation of sGC significantly counteracted TGFß1-induced cell proliferation, migration, invasiveness, and acquisition of a myofibroblast-like phenotype, as shown by a significant downregulation of FAP, ACTA2, COL1A1, COL1A2, FN1, MMP2, TIMP1, and TIMP2 mRNA levels, as well as by a significant reduction in α-smooth muscle actin, N-cadherin, COL1A1, and FN-EDA protein expression. In addition, pretreatment with the sGC stimulator was capable of significantly dampening TGFß1-induced acquisition of a contractile phenotype by conjunctival fibroblasts, as well as phosphorylation of Smad3 and release of the proinflammatory cytokines IL-1ß and IL-6. Taken together, our findings are the first to demonstrate the effectiveness of pharmacological sGC stimulation in counteracting conjunctival fibroblast-to-myofibroblast transition, thus providing a promising scientific background to further explore the feasibility of sGC stimulators as potential new adjuvant therapeutic compounds to treat conjunctival fibrotic conditions.

Extracellular Lactic Acidosis of the Tumor Microenvironment Drives Adipocyte-to-Myofibroblast Transition Fueling the Generation of Cancer-Associated Fibroblasts.

Lactic acidosis characterizes the tumor microenvironment (TME) and is involved in the mechanisms leading to cancer progression and dissemination through the reprogramming of tumor and local host cells (e.g., endothelial cells, fibroblasts, and immune cells). Adipose tissue also represents a crucial component of the TME which is receiving increasing attention due to its pro-tumoral activity, however, to date, it is not known whether it could be affected by the acidic TME. Now, emerging evidence from chronic inflammatory and fibrotic diseases underlines that adipocytes may give rise to pathogenic myofibroblast-like cells through the adipocyte-to-myofibroblast transition (AMT). Thus, our study aimed to investigate whether extracellular acidosis could affect the AMT process, sustaining the acquisition by adipocytes of a cancer-associated fibroblast (CAF)-like phenotype with a pro-tumoral activity. To this purpose, human subcutaneous adipose-derived stem cells committed to adipocytes (acADSCs) were cultured under basal (pH 7.4) or lactic acidic (pH 6.7, 10 mM lactate) conditions, and AMT was evaluated with quantitative PCR, immunoblotting, and immunofluorescence analyses. We observed that lactic acidosis significantly impaired the expression of adipocytic markers while inducing myofibroblastic, pro-fibrotic, and pro-inflammatory phenotypes in acADSCs, which are characteristic of AMT reprogramming. Interestingly, the conditioned medium of lactic acidosis-exposed acADSC cultures was able to induce myofibroblastic activation in normal fibroblasts and sustain the proliferation, migration, invasion, and therapy resistance of breast cancer cells in vitro. This study reveals a previously unrecognized relationship between lactic acidosis and the generation of a new CAF-like cell subpopulation from adipocytic precursor cells sustaining tumor malignancy.

The Role of Pro-fibrotic Myofibroblasts in Systemic Sclerosis: From Origin to Therapeutic Targeting.

Systemic sclerosis (SSc, scleroderma) is a complex connective tissue disorder characterized by multisystem clinical manifestations resulting from immune dysregulation/autoimmunity, vasculopathy, and, most notably, progressive fibrosis of the skin and internal organs. In recent years, it has been observed that the main drivers of SSc-related tissue fibrosis are myofibroblasts, a type of mesenchymal cells with both the extracellular matrix-synthesizing features of fibroblasts and the cytoskeletal characteristics of contractile smooth muscle cells. The accumulation and persistent activation of pro-fibrotic myofibroblasts during SSc development and progression result in elevated mechanical stress and reduced matrix plasticity within the affected tissues and may be ascribed to a reduced susceptibility of these cells to pro-apoptotic stimuli, as well as their increased formation from tissue-resident fibroblasts or transition from different cell types. Given the crucial role of myofibroblasts in SSc pathogenesis, finding the way to inhibit myofibroblast differentiation and accumulation by targeting their formation, function, and survival may represent an effective approach to hamper the fibrotic process or even halt or reverse established fibrosis. In this review, we discuss the role of myofibroblasts in SSc-related fibrosis, with a special focus on their cellular origin and the signaling pathways implicated in their formation and persistent activation. Furthermore, we provide an overview of potential therapeutic strategies targeting myofibroblasts that may be able to counteract fibrosis in this pathological condition.

Enthesopathy and involvement of synovio-entheseal complex in systemic sclerosis: an ultrasound pilot study.

OBJECTIVES: SSc is a chronic autoimmune disease characterized by inflammation of the skin and multiple internal organs. Articular involvement is one of the main features of SSc, and typical hallmarks of SpA have been found in SSc patients. The aim of the present study was to estimate the prevalence of entheseal and synovio-entheseal complex (SEC) alterations in a cohort of SSc patients. METHODS: One hundred SSc patients and 25 healthy subjects were included in this cross-sectional study. The enthesis sites of lateral epicondylar common extensor tendons (CET) and the enthesis of the Glasgow Ultrasound Enthesis Scoring System were evaluated. SEC involvement was evaluated only at CET enthesis. RESULTS: In SSc, the Glasgow Ultrasound Enthesis Scoring System score was significantly higher (median 4.0, interquartile range 2.0-7.0) than in controls (median 1.0, interquartile range 0.0-3.0) (P < 0.0001). CET enthesis of SSc patients showed more frequent US B-mode alterations than that of controls (χ2 = 11.47, P = 0.0007 for size; χ2 = 13.79, P = 0.0002 for cortical irregularity, χ2 = 5.24, P = 0.022 for calcification/enthesophytes). Power Doppler US signal at CET enthesis was significantly more frequent in SSc patients than in healthy controls (χ2 = 9.11, P = 0.0025), as was the concomitant SEC involvement (χ2 = 8.52, P = 0.0035). CONCLUSION: These data show that SSc patients frequently present US features of enthesopathy. Moreover, CET enthesopathy was correlated with SEC inflammation, suggesting that entheseal inflammation in SSc may share the same micro-anatomical targets as found in SpA.

Systemic Sclerosis Serum Significantly Impairs the Multi-Step Lymphangiogenic Process: in Vitro Evidence.

In systemic sclerosis (SSc), the possible involvement of lymphatic microcirculation and lymphangiogenesis has traditionally been overshadowed by the greater emphasis placed on dysfunctional blood vascular system and angiogenesis. In the present in vitro study, we explore for the first time whether the SSc microenvironment may interfere with lymphangiogenesis, a complex, multi-step process in which lymphatic microvascular endothelial cells (LMVECs) sprout, migrate, and proliferate to generate new lymphatic capillaries. Normal human adult dermal LMVECs from three donors were treated with serum from SSc patients (n = 8), serum from healthy individuals (n = 8), or recombinant human vascular endothelial growth factor (VEGF)-C as a positive control for lymphangiogenesis. Cell proliferation, Boyden chamber Matrigel chemoinvasion, wound healing capacity, and lymphatic capillary morphogenesis on Geltrex were assayed. VEGF-C serum levels were measured by enzyme-linked immunosorbent assay. Gene and protein expression levels of the lymphangiogenic orchestrators VEGF receptor-3 (VEGFR-3)/Flt-4 and neuropilin-2 (NRP-2) were determined by real-time PCR and Western blotting, respectively. Conditioning with SSc serum significantly inhibited LMVEC proliferation, Matrigel invasion, and wound healing capacity with respect to healthy serum. The ability of LMVECs to form lymphatic tubes on Geltrex was also severely compromised in the presence of SSc serum. VEGF-C levels were comparable in SSc and healthy sera. Treatment with SSc serum resulted in a significant downregulation of both VEGFR-3/Flt-4 and NRP-2 mRNA and protein levels. In SSc, the pathologic environment severely hampers every lymphangiogenesis step, likely through the reduction of pro-lymphangiogenic VEGFR-3/NRP-2 co-receptor signaling. The impairment of the lymphangiogenic process opens a new scenario underlying SSc vascular pathophysiology, which is worth investigating further.

TNF-α/TNF-R System May Represent a Crucial Mediator of Proliferative Synovitis in Hemophilia A.

Hemophilic arthropathy (HA) typically begins with proliferative synovitis that shares some similarities with inflammatory arthritides, in which the proinflammatory cytokine tumor necrosis factor (TNF)-α has a crucial pathogenetic role. Inappropriate release of TNF-α was shown to contribute to arthropathy development following intra-articular bleeding in hemophilic mice. Here, we were interested in determining whether systemic levels of TNF-α and synovial tissue expression of the TNF-α/TNF receptor (TNF-R) system could be increased and related to joint damage in hemophilia A patients with severe HA. Serum levels of TNF-α measured by quantitative enzyme-linked immunosorbent assay (ELISA) were significantly increased in HA patients (n = 67) compared to healthy controls (n = 20). In HA patients, elevated TNF-α levels were significantly associated with the number of hemarthroses, the grade of synovial hypertrophy, and both the clinical World Federation of Hemophilia score and ultrasound score. The expression of TNF-α, TNF-R1, and TNF-R2 was strongly increased in HA synovium (n = 10) compared to the non-inflamed osteoarthritis control synovium (n = 8), as assessed by both immunohistochemistry and Western blotting. Increased protein levels of TNF-α, TNF-R1, and TNF-R2 were retained in vitro by HA fibroblast-like synoviocytes (n = 6) with respect to osteoarthritis control fibroblast-like synoviocytes (n = 6). Stimulation with TNF-α resulted in a significant increase in HA fibroblast-like synoviocyte proliferation quantified by the water-soluble tetrazolium (WST)-1 assay, while it had no relevant effect on osteoarthritis fibroblast-like synoviocytes. Quantification of active/cleaved caspase-3 by ELISA demonstrated that TNF-α did not induce apoptosis either in HA or in osteoarthritis fibroblast-like synoviocytes. The TNF-α/TNF-R system may represent a crucial mediator of proliferative synovitis and, therefore, a new attractive target for the prevention and treatment of joint damage in HA patients. Our findings provide the groundwork for further clinical investigation of anti-TNF-α therapeutic feasibility in hemophiliacs.

Slit2/Robo4 axis may contribute to endothelial cell dysfunction and angiogenesis disturbance in systemic sclerosis.

OBJECTIVE: In systemic sclerosis (SSc), early microvascular injury is followed by impaired angiogenesis and peripheral capillary loss. Here, we investigated the possible contribution of the neurovascular guidance molecule Slit2 and its Roundabout (Robo) receptors to SSc-related endothelial cell dysfunction. METHODS: Circulating Slit2 levels were measured in patients with SSc and healthy controls. Slit2, Robo1 and Robo4 expression was investigated in SSc and healthy skin biopsies and explanted dermal microvascular endothelial cells (MVECs). Slit2/Robo4 function in MVEC angiogenesis was studied by cell viability, wound healing and capillary-like tube formation assays. RESULTS: Circulating Slit2 was significantly increased in either SSc or patients with a very early diagnosis of SSc (VEDOSS) compared with controls. Interestingly, serum Slit2 levels were raised in patients with VEDOSS with nailfold videocapillaroscopy (NVC) abnormalities, while they were similar in VEDOSS with normal NVC and controls. In SSc, Slit2 and Robo4 expression was upregulated in clinically affected skin and explanted MVECs in respect to controls. The angiogenic performance of healthy MVECs was significantly reduced after challenge with recombinant human Slit2 or SSc sera. These inhibitory effects were significantly attenuated when SSc sera were preincubated with an anti-Slit2 blocking antibody. In vitro angiogenesis was severely compromised in SSc-MVECs and could be significantly ameliorated by Slit2 neutralisation or ROBO4 gene silencing. Slit2/Robo4 axis interfered with angiogenesis through the inhibition of Src kinase phosphorylation. CONCLUSIONS: In SSc, increased circulating levels of Slit2 and activation of the Slit2/Robo4 antiangiogenic axis may contribute to peripheral microangiopathy since the very early phase of the disease.

Evidence for a Derangement of the Microvascular System in Patients with a Very Early Diagnosis of Systemic Sclerosis.

OBJECTIVE: To investigate whether patients with a very early diagnosis of systemic sclerosis (VEDOSS) may already present circulating markers and in vitro signs of microvascular dysfunction. METHODS: Serum samples were obtained from 55 patients with systemic sclerosis (SSc), 25 patients with VEDOSS, and 55 matched healthy controls (HC). Serum levels of pan-vascular endothelial growth factor (VEGF) and soluble neuropilin-1 (sNRP-1) were measured by ELISA. Human dermal microvascular endothelial cells (H-MVEC) were cultured and stimulated with SSc, VEDOSS, and HC sera. Protein expression of NRP-1 was analyzed by Western blotting, cell proliferation by 5'-bromodeoxyuridine assay, migration capacity by wound-healing assay, and capillary-like tube formation by Matrigel assay. RESULTS: Serum levels of pan-VEGF were increased in patients with VEDOSS and SSc versus HC (p = 0.05 and p = 0.003, respectively). Serum levels of sNRP-1 were significantly reduced in patients with VEDOSS and SSc compared with controls (p = 0.012 and p = 0.027, respectively). NRP-1 expression was decreased in H-MVEC stimulated with VEDOSS sera (p < 0.001 vs HC). Proliferation was reduced in H-MVEC stimulated either with VEDOSS or SSc sera in comparison with HC sera (p = 0.015 and p = 0.043, respectively). Wound healing was compromised in H-MVEC stimulated with VEDOSS and SSc sera versus HC sera (p < 0.01 for both). Capillarogenesis was decreased in H-MVEC stimulated with VEDOSS sera (p < 0.01) and SSc sera (p < 0.001) compared with cells stimulated with HC sera. CONCLUSION: Similar to patients with SSc, patients with VEDOSS already present biological signs of endothelial dysfunction. Our data demonstrate that VEDOSS sera significantly modify endothelial cell behavior and impair the angiogenic potential of the microvascular system.

Clinical, instrumental, serological and histological findings suggest that hemophilia B may be less severe than hemophilia A.

Recent evidence suggests that patients with severe hemophilia B may have a less severe disease compared to severe hemophilia A. To investigate clinical, radiological, laboratory and histological differences in the arthropathy of severe hemophilia A and hemophilia B, 70 patients with hemophilia A and 35 with hemophilia B with at least one joint bleeding were consecutively enrolled. Joint bleedings (<10, 10-50, >50), regimen of treatment (prophylaxis/on demand), World Federation of Hemophilia, Pettersson and ultrasound scores, serum soluble RANK ligand and osteoprotegerin were assessed in all patients. RANK, RANK ligand and osteoprotegerin expression was evaluated in synovial tissue from 18 hemophilia A and 4 hemophilia B patients. The percentage of patients with either 10-50 or more than 50 hemarthrosis was greater in hemophilia A than in hemophilia B (P<0.001 and P=0.03, respectively), while that with less than 10 hemarthrosis was higher in hemophilia B (P<0.0001). World Federation of Hemophilia (36.6 vs. 20.2; P<0.0001) and ultrasound (10.9 vs. 4.3; P<0.0001) score mean values were significantly higher in hemophilia A patients. Serum osteoprotegerin and soluble RANK ligand were decreased in hemophilia A versus hemophilia B (P<0.0001 and P=0.006, respectively). Osteoprotegerin expression was markedly reduced in synovial tissue from hemophilia A patients. In conclusion, the reduced number of hemarthrosis, the lower World Federation of Hemophilia and ultrasound scores, and higher osteoprotegerin expression in serum and synovial tissue in hemophilia B suggest that hemophilia B is a less severe disease than hemophilia A. Osteoprotegerin reduction seems to play a pivotal role in the progression of arthropathy in hemophilia A.

Decreased expression of neuropilin-1 as a novel key factor contributing to peripheral microvasculopathy and defective angiogenesis in systemic sclerosis.

OBJECTIVES: In systemic sclerosis (SSc), vascular involvement is characterised by vascular endothelial growth factor (VEGF)-A/VEGF receptor (VEGFR) system disturbances. Neuropilin-1 (NRP1), a receptor for both class-3 semaphorins (Sema3s) and VEGF-A, is required for optimal VEGF-A/VEGFR-2 signalling. Here, we investigated the possible involvement of Sema3A/NRP1 axis in SSc. METHODS: Circulating Sema3A and soluble NRP1 (sNRP1) were measured in patients with SSc and controls. NRP1 and Sema3A expression in skin biopsies was evaluated by immunofluorescence and western blotting. NRP1 expression was assessed in SSc and healthy dermal microvascular endothelial cells (SSc-MVECs and H-MVECs), and in SSc and control endothelial progenitor cell (EPC)-derived endothelial cells (ECs). The possible impact of transcription factor Friend leukaemia integration 1 (Fli1) deficiency on endothelial NRP1 expression was investigated by gene silencing. The binding of Fli1 to NRP1 gene promoter was evaluated using chromatin immunoprecipitation. Capillary morphogenesis was performed on Matrigel. RESULTS: Decreased sNRP1 levels in SSc were associated with active and late nailfold videocapillaroscopy patterns and digital ulcers. No difference in Sema3A was found between patients and controls. NRP1 was significantly decreased in SSc-MVECs both ex vivo and in vitro. NRP1 and Fli1 significantly decreased in H-MVECs challenged with SSc sera, while they were not different in SSc and control EPC-derived ECs. Fli1 occupied the NRP1 gene promoter and Fli1 gene silencing reduced NRP1 expression in H-MVECs. NRP1 gene silencing in H-MVECs resulted in a significantly impaired angiogenic capacity comparable to that of cells treated with SSc sera. CONCLUSION: In SSc, NRP1 deficiency may be an additional factor in the perturbed VEGF-A/VEGFR-2 system contributing to peripheral microvasculopathy and defective angiogenesis.

Bosentan blocks the antiangiogenic effects of sera from systemic sclerosis patients: an in vitro study.

OBJECTIVES: In systemic sclerosis (SSc), clinical evidence has shown that Bosentan may foster the regeneration of the peripheral microcirculatory network. The aim of this study was to verify in vitro the influence of Bosentan on the angiogenic performance of dermal microvascular endothelial cells (MVECs) and its possible capacity to counteract the antiangiogenic effects of SSc sera. METHODS: Healthy dermal MVECs were challenged with Bosentan at different concentrations (0.1 µM, 1 µM, 10 µM) or with sera from patients with diffuse cutaneous SSc (n=8) and healthy subjects (n=8), alone or in combination with Bosentan (10 µM). Cell viability and chemoinvasion were determined by WST-1 and Boyden chamber assays, respectively. Angiogenesis was evaluated by capillary morphogenesis on Matrigel. RESULTS: Challenge of dermal MVECs with SSc sera induced a significant reduction in angiogenesis (p<0.005 vs. basal condition; p<0.001 vs. healthy sera). The addition of Bosentan could significantly restore angiogenesis in the presence of SSc sera (p<0.01 vs. SSc sera alone). Healthy sera promoted cell viability which was, instead, significantly reduced with SSc sera (p<0.005 vs. healthy sera). The addition of Bosentan to MVECs challenged with SSc sera significantly increased cell viability (p<0.005 vs. SSc sera alone), reaching levels similar to MVECs treated with healthy sera. Co-incubation of MVECs with Bosentan and SSc sera significantly increased chemoinvasion (p<0.005 vs. SSc sera alone) which was inhibited by SSc sera (<0.001 vs. healthy sera). CONCLUSIONS: Bosentan effectively counteracts the antiangiogenic effects of SSc sera on dermal MVECs and fosters the restoration of a proangiogenic environment.

Disease activity improvement in rheumatoid arthritis treated with tumor necrosis factor-α inhibitors correlates with increased soluble Fas levels.

OBJECTIVE: Rheumatoid arthritis (RA) is characterized by chronic synovial inflammation and hyperplasia. Tumor necrosis factor-α (TNF-α) plays a pivotal role in RA by interfering with the Fas-Fas ligand (FasL) proapoptotic pathway. We investigated the circulating levels of soluble Fas (sFas) and soluble FasL (sFasL), and their possible correlation with disease activity and improvement after anti-TNF-α treatment in RA. METHODS: Serum levels of sFas and sFasL were measured by quantitative ELISA in 52 patients with RA before and after 3 months of anti-TNF-α treatment (adalimumab, n = 32; infliximab, n = 20). Disease activity measures [Disease Activity Score at 28 joints-erythrocyte sedimentation rate (DAS28-ESR), C-reactive protein (CRP)] were recorded before and after treatment. Forty age-matched and sex-matched healthy subjects served as controls. RESULTS: No significant differences in serum sFas levels were detected between anti-TNF-α-naive patients with RA and controls. After anti-TNF-α treatment, serum sFas levels significantly increased in patients with RA compared to both anti-TNF-α-naive patients and controls. Increased sFas levels inversely correlated with disease activity variables (DAS28-ESR: r = -0.739, CRP: r = -0.636, both p < 0.001). No significant differences in sFasL levels were detected in patients with RA before and after anti-TNF-α treatment. CONCLUSION: In RA, an increase in sFas levels closely correlates with improvement in disease activity induced by TNF-α inhibitors, suggesting their ability to modulate Fas-mediated synoviocyte apoptosis.

Decreased expression of the endothelial cell-derived factor EGFL7 in systemic sclerosis: potential contribution to impaired angiogenesis and vasculogenesis.

INTRODUCTION: Microvascular damage and defective angiogenesis and vasculogenesis have a major role in the pathogenesis of systemic sclerosis (SSc). Epidermal growth factor-like domain 7 (EGFL7) is a proangiogenic molecule which is predominantly expressed and secreted by endothelial cells and their progenitors and controls vascular development and integrity. In this study, we investigated the possible involvement of EGFL7 in SSc. METHODS: Serum EGFL7 levels from 60 patients with SSc and 35 age- and sex-matched healthy controls were examined by colorimetric sandwich enzyme-linked immunosorbent assay. The expression of EGFL7 in forearm skin biopsies (n = 16 SSc, n = 10 controls), cultured dermal microvascular endothelial cells (MVECs) (n = 3 SSc, n = 3 controls) and late-outgrowth peripheral blood endothelial progenitor cell (EPC)-derived endothelial cells (n = 15 SSc, n = 8 controls) was investigated by immunofluorescence and Western blotting. RESULTS: Serum EGFL7 levels were detectable in 68.6% of healthy controls and 45% of SSc cases (P < 0.05). Circulating levels of EGFL7 were significantly decreased in SSc patients compared with healthy controls (P = 0.01). Serum levels of EGFL7 were significantly lower in both limited cutaneous SSc and diffuse cutaneous SSc patients than in controls (P = 0.02 and P = 0.04, respectively). In SSc, decreased serum EGFL7 levels were significantly correlated with the severity of nailfold capillary abnormalities. Patients with the most severe capillary changes and digital ulcers had serum EGFL7 levels significantly lower than healthy controls, while the EGFL7 levels did not differ significantly between controls and SSc patients with less capillary damage and lack of digital ulcers. Endothelial EGFL7 expression was strongly downregulated or even almost completely undetectable in SSc-affected dermis compared with controls (P < 0.001). In cultured SSc dermal MVECs and late-outgrowth peripheral blood EPC-derived endothelial cells, EGFL7 was significantly downregulated compared with cells obtained from healthy subjects (P < 0.01 and P < 0.001, respectively). CONCLUSIONS: Our findings suggest that the loss of EGFL7 expression in endothelial cells and their progenitors might play a role in the development and progression of peripheral microvascular damage and the defective vascular repair process characteristic of SSc.

Differential expression of junctional adhesion molecules in different stages of systemic sclerosis.

OBJECTIVE: Systemic sclerosis (SSc) is characterized by early perivascular inflammation, microvascular endothelial cell (MVEC) activation/damage, and defective angiogenesis. Junctional adhesion molecules (JAMs) regulate leukocyte recruitment to sites of inflammation and ischemia-reperfusion injury, vascular permeability, and angiogenesis. This study was undertaken to investigate the possible role of JAMs in SSc pathogenesis. METHODS: JAM-A and JAM-C expression levels in skin biopsy samples from 25 SSc patients and 15 healthy subjects were investigated by immunohistochemistry and Western blotting. Subcellular localization of JAMs in cultured healthy dermal MVECs and SSc MVECs was assessed by confocal microscopy. Serum levels of soluble JAM-A (sJAM-A) and sJAM-C in 64 SSc patients and 32 healthy subjects were examined by enzyme-linked immunosorbent assay. RESULTS: In control skin, constitutive JAM-A expression was observed in MVECs and fibroblasts. In early-stage SSc skin, JAM-A expression was strongly increased in MVECs, fibroblasts, and perivascular inflammatory cells. In late-stage SSc, JAM-A expression was decreased compared with controls. JAM-C was weakly expressed in control and late-stage SSc skin, while it was strongly expressed in MVECs, fibroblasts, and inflammatory cells in early-stage SSc. Surface expression of JAM-A was higher in early-stage SSc MVECs and increased in healthy MVECs stimulated with early-stage SSc sera. JAM-C was cytoplasmic in resting healthy MVECs, while it was recruited to the cell surface upon challenge with early-stage SSc sera. Early-stage SSc MVECs exhibited constitutive surface JAM-C expression. In SSc, increased levels of sJAM-A and sJAM-C correlated with early disease and measures of vascular damage. CONCLUSION: Our findings indicate that JAMs may participate in MVEC activation, inflammatory processes, and impaired angiogenesis in different stages of SSc.

RANK-RANKL-OPG in hemophilic arthropathy: from clinical and imaging diagnosis to histopathology.

OBJECTIVE: Hemarthrosis triggers hemophilic arthropathy, involving the target joints. The histopathogenesis of blood-induced joint damage remains unclear. The triad of receptor activator of nuclear factor-κB (RANK), RANK ligand (RANKL), and osteoprotegerin (OPG; RANK-RANKL-OPG) controls bone turnover. Our aim was to evaluate RANK-RANKL-OPG expression in the synovium of hemophilic patients with severe arthropathy. METHODS: Synovial biopsies were obtained from 18 patients with hemophilic arthropathy and 16 with osteoarthritis (OA) who were undergoing total knee replacement and synovectomy. The severity of hemophilic arthropathy was evaluated according to ultrasonography score, the World Federation of Hemophilia (WFH) orthopedic joint scale, and the radiographic Pettersson score. RANK-RANKL-OPG expression was examined by immunohistochemistry and Western blotting. Serum levels of soluble RANKL (sRANKL) and OPG from an extended group of 67 patients with hemophilic arthropathy and 30 healthy controls were measured by ELISA. RESULTS: The mean ultrasonography, WFH orthopedic joint scale, and Pettersson scores in patients with hemophilic arthropathy indicated severe arthropathy. A decreased expression of OPG was found in hemophilic arthropathy synovium compared with patients with OA. RANK and RANKL immunopositivity was strong in the lining and sublining layers in hemophilic arthropathy synovial tissue. Western blotting confirmed the immunohistological findings. Serum levels of sRANKL and OPG in patients with hemophilia were lower than in healthy controls. CONCLUSION: In hemophilic arthropathy, the synovium highly expressed RANK and RANKL, whereas OPG immunopositivity decreased, suggesting an osteoclastic activation. Low tissue expression of OPG paralleled the serum levels of this protein and the severity of hemophilic arthropathy assessed by ultrasonography, Pettersson, and WFH orthopedic joint scale scores.

Increased serum levels and tissue expression of matrix metalloproteinase-12 in patients with systemic sclerosis: correlation with severity of skin and pulmonary fibrosis and vascular damage.

OBJECTIVE: To determine serum concentrations and tissue expression of matrix metalloproteinase-12 (MMP-12) and their correlation with clinical features in patients with systemic sclerosis (SSc). METHODS: Serum MMP-12 levels from 72 patients with SSc and 42 healthy volunteers were examined by ELISA. Immunohistochemical expression of MMP-12 was analysed in skin biopsies from 20 patients with SSc and 13 healthy subjects and lung biopsies from three patients with SSc-related interstitial lung disease (ILD) and five controls. RESULTS: Circulating levels of MMP-12 were significantly increased in patients with SSc compared with healthy controls. Serum MMP-12 levels were significantly higher in both patients with limited cutaneous SSc and those with diffuse cutaneous SSc than in healthy controls, and correlated positively with the extent of skin involvement. MMP-12 levels were raised in SSc patients with ILD compared with patients without ILD, and correlated with severity of lung restriction. Increased serum levels of MMP-12 were also associated with the presence of digital ulcers and severity of nailfold capillary abnormalities. In contrast to almost undetectable MMP-12 expression in healthy skin, MMP-12 was strongly expressed in keratinocytes, dermal endothelial cells, fibroblasts/myofibroblasts and inflammatory cells in the skin of patients with SSc. Affected lung tissue from patients with SSc-related ILD showed strong MMP-12 expression in capillary vessels, inflammatory cells, alveolar macrophages and fibroblasts in the thickened alveolar septa, while faint expression was observed in normal lung tissue. CONCLUSIONS: MMP-12 levels are increased in patients with SSc and are associated with severity of skin and pulmonary fibrosis and peripheral vascular damage.

Bone marrow-derived mesenchymal stem cells from early diffuse systemic sclerosis exhibit a paracrine machinery and stimulate angiogenesis in vitro.

OBJECTIVE: To characterise bone marrow-derived mesenchymal stem cells (MSCs) from patients with systemic sclerosis (SSc) for the expression of factors implicated in MSC recruitment at sites of injury, angiogenesis and fibrosis. The study also analysed whether the production/release of bioactive mediators by MSCs were affected by stimulation with cytokines found upregulated in SSc serum and tissues, and whether MSCs could modulate dermal microvascular endothelial cell (MVEC) angiogenesis. METHODS: MSCs obtained from five patients with early severe diffuse SSc (SSc-MSCs) and five healthy donors (H-MSCs) were stimulated with vascular endothelial growth factor (VEGF), transforming growth factor ß (TGFß) or stromal cell-derived factor-1 (SDF-1). Transcript and protein levels of SDF-1 and its receptor CXCR4, VEGF, TGFß(1) and receptors TßRI and TßRII were evaluated by quantitative real-time PCR, western blotting and confocal microscopy. VEGF, SDF-1 and TGFß(1) secretion in culture supernatant was measured by ELISA. MVEC capillary morphogenesis was performed on Matrigel with the addition of MSC-conditioned medium. RESULTS: In SSc-MSCs the basal expression of proangiogenic SDF-1/CXCR4 and VEGF was significantly increased compared with H-MSCs. SSc-MSCs constitutively released higher levels of SDF-1 and VEGF. SDF-1/CXCR4 were upregulated after VEGF stimulation and CXCR4 redistributed from the cytoplasm to the cell surface. VEGF was increased by SDF-1 challenge. VEGF, TGFß and SDF-1 stimulation upregulated TGFß(1), TßRI and TßRII in SSc-MSCs. TßRII redistributed from the cytoplasm to focal adhesion contacts. SSc-MSC-conditioned medium showed a greater proangiogenic effect on MVECs than H-MSCs. Experiments with blocking antibodies showed that MSC-derived cytokines were responsible for this potent proangiogenic effect. CONCLUSION: SSc-MSCs constitutively overexpress and release bioactive mediators/proangiogenic factors and potentiate dermal MVEC angiogenesis.

Overexpression of VEGF165b, an inhibitory splice variant of vascular endothelial growth factor, leads to insufficient angiogenesis in patients with systemic sclerosis.

RATIONALE: Systemic sclerosis (SSc) is characterized by widespread microangiopathy, fibrosis, and autoimmunity. Despite the lack of angiogenesis, the expression of vascular endothelial growth factor A (VEGF) was shown to be upregulated in SSc skin and circulation; however, previous studies did not distinguish between proangiogenic VEGF(165) and antiangiogenic VEGF(165)b isoforms, which are generated by alternative splicing in the terminal exon of VEGF pre-RNA. OBJECTIVE: We investigated whether VEGF isoform expression could be altered in skin and circulation of patients with SSc. METHODS AND RESULTS: Here, we show that the endogenous antiangiogenic VEGF(165)b splice variant is selectively overexpressed at both the mRNA and protein levels in SSc skin. Elevated VEGF(165)b expression correlated with increased expression of profibrotic transforming growth factor-ß1 and serine/arginine protein 55 splicing factor in keratinocytes, fibroblasts, endothelial cells, and perivascular inflammatory cells. Circulating levels of VEGF(165)b were significantly higher in patients with SSc than in control subjects. Microvascular endothelial cells (MVECs) isolated from SSc skin expressed and released higher levels of VEGF(165)b than healthy MVECs. Transforming growth factor-ß1 upregulated the expression of VEGF(165)b and serine/arginine protein 55 in both SSc and healthy MVECs. In SSc MVECs, VEGF receptor-2 was overexpressed, but its phosphorylation was impaired. Recombinant VEGF(165)b and SSc-MVEC-conditioned medium inhibited VEGF(165)-mediated VEGF receptor-2 phosphorylation and capillary morphogenesis in healthy MVECs. The addition of anti-VEGF(165)b blocking antibodies abrogated the antiangiogenic effect of SSc-MVEC-conditioned medium. Capillary morphogenesis was severely impaired in SSc MVECs and could be ameliorated by treatment with recombinant VEGF(165) and anti-VEGF(165)b blocking antibodies. CONCLUSIONS: In SSc, a switch from proangiogenic to antiangiogenic VEGF isoforms may have a crucial role in the insufficient angiogenic response to chronic ischemia.