The pathology of scleroderma vascular disease

Extensive and Persistent Extravascular Dermal Fibrin Deposition Characterizes Systemic Sclerosis

Systemic sclerosis (SSc) is an autoimmune disease characterized by progressive multiorgan fibrosis. While the cause of SSc remains unknown, a perturbed vasculature is considered a critical early step in the pathogenesis. Using fibrinogen as a marker of vascular leakage, we found extensive extravascular fibrinogen deposition in the dermis of both limited and diffuse systemic sclerosis disease, and it was present in both early and late-stage patients. Based on a timed series of excision wounds, retention on the fibrin deposit of the splice variant domain, fibrinogen αEC, indicated a recent event, while fibrin networks lacking the αEC domain were older. Application of this timing tool to SSc revealed considerable heterogeneity in αEC domain distribution providing unique insight into disease activity. Intriguingly, the fibrinogen-αEC domain also accumulated in macrophages. These observations indicate that systemic sclerosis is characterized by ongoing vascular leakage resulting in extensive interstitial fibrin deposition that is either continually replenished and/or there is impaired fibrin clearance. Unresolved fibrin deposition might then incite chronic tissue remodeling.

Sphingosine 1-phosphate receptor-targeted therapeutics in rheumatic diseases

Sphingosine 1-phosphate (S1P), which acts via G protein-coupled S1P receptors (S1PRs), is a bioactive lipid essential for vascular integrity and lymphocyte trafficking. The S1P-S1PR signalling axis is a key component of the inflammatory response in autoimmune rheumatic diseases. Several drugs that target S1PRs have been approved for the treatment of multiple sclerosis and inflammatory bowel disease and are under clinical testing for patients with systemic lupus erythematosus (SLE). Preclinical studies support the hypothesis that targeting the S1P-S1PR axis would be beneficial to patients with SLE, rheumatoid arthritis (RA) and systemic sclerosis (SSc) by reducing pathological inflammation. Whereas most preclinical research and development efforts are focused on reducing lymphocyte trafficking, protective effects of circulating S1P on endothelial S1PRs, which maintain the vascular barrier and enable blood circulation while dampening leukocyte extravasation, have been largely overlooked. In this Review, we take a holistic view of S1P-S1PR signalling in lymphocyte and vascular pathobiology. We focus on the potential of S1PR modulators for the treatment of SLE, RA and SSc and summarize the rationale, pathobiology and evidence from preclinical models and clinical studies. Improved understanding of S1P pathobiology in autoimmune rheumatic diseases and S1PR therapeutic modulation is anticipated to lead to efficacious and safer management of these diseases.

Morphea mimicking facial capillary malformations: Two new cases and review of the literature

Morphea and facial capillary malformations (port-wine stains) are distinct conditions that can affect the pediatric population. Early localized morphea mimicking a capillary malformation is an uncommon clinical presentation. We present two new cases of girls, aged 2 and 3 years, who presented with erythematous patches, initially diagnosed as capillary malformations, which were later diagnosed as morphea. We also performed a literature review, yielding 12 additional cases that underscore that the unusual presentation of morphea may delay correct diagnosis. Although early management of morphea reduces long-term sequelae, it is important to delay laser treatment for selected acquired vascular malformations, until the diagnosis of morphea is excluded.

Change of the microvascularization in systemic sclerosis, a matter of air

Systemic sclerosis (SSc) is a rare complex disease, characterized by microvascular damage, auto-immunity, and fibrosis. Nailfold capillary microscopy (NCM), a safe and noninvasive imaging technique, can be used to visualize specific microvascular alterations in SSc. In this review, we discuss an interesting case of a patient with changes in microvascular pattern on NCM after pulmonary transplantation. We provide an overview of microvascular alterations in systemic sclerosis and the evidence in the literature about the effect of vasoactive and immunomodulation therapy on these vascular changes. We also outline the influence of pulmonal pathology, such as interstitial lung disease and pulmonary arterial hypertension, on the capillaroscopic pattern, and finally, we discuss how NCM could possibly serve as a biomarker of treatment.

Chemical exposure-induced systemic fibrosing disorders: Novel insights into systemic sclerosis etiology and pathogenesis

Numerous drugs and chemical substances are capable of inducing exaggerated tissue fibrotic responses. The vast majority of these agents cause localized fibrotic tissue reactions or fibrosis confined to specific organs. Although much less frequent, chemically-induced systemic fibrotic disorders have been described, sometimes occurring as temporally confined outbreaks. These include the Toxic Oil Syndrome (TOS), the Eosinophilia-Myalgia Syndrome (EMS), and Nephrogenic Systemic Fibrosis (NSF). Although each of these disorders displays some unique characteristics, they all share crucial features with Systemic Sclerosis (SSc), the prototypic idiopathic systemic fibrotic disease, including vasculopathy, chronic inflammatory cell infiltration of affected tissues, and cutaneous and visceral tissue fibrosis. The study of the mechanisms and molecular alterations involved in the development of the chemically-induced systemic fibrotic disorders has provided valuable clues that may allow elucidation of SSc etiology and pathogenesis. Here, we review relevant aspects of the TOS, EMS, and NSF epidemic outbreaks of chemically-induced systemic fibrosing disorders that provide strong support to the hypothesis that SSc is caused by a toxic or biological agent that following its internalization by endothelial cells induces in genetically predisposed individuals a series of molecular alterations that result in the development of SSc clinical and pathological alterations.

Existing and novel biomarkers for precision medicine in systemic sclerosis

The discovery and validation of biomarkers resulting from technological advances in the analysis of genomic, transcriptomic, lipidomic and metabolomic pathways involved in the pathogenesis of complex human diseases have led to the development of personalized and rationally designed approaches for the clinical management of such disorders. Although some of these approaches have been applied to systemic sclerosis (SSc), an unmet need remains for validated, non-invasive biomarkers to aid in the diagnosis of SSc, as well as in the assessment of disease progression and response to therapeutic interventions. Advances in global transcriptomic technology over the past 15 years have enabled the assessment of microRNAs that circulate in the blood of patients and the analysis of the macromolecular content of a diverse group of lipid bilayer membrane-enclosed extracellular vesicles, such as exosomes and other microvesicles, which are released by all cells into the extracellular space and circulation. Such advances have provided new opportunities for the discovery of biomarkers in SSc that could potentially be used to improve the design and evaluation of clinical trials and that will undoubtedly enable the development of personalized and individualized medicine for patients with SSc.

Macrophages Guard Endothelial Lineage by Hindering Endothelial-to-Mesenchymal Transition: Implications for the Pathogenesis of Systemic Sclerosis

The signals that control endothelial plasticity in inflamed tissues have only been partially characterized. For example, it has been shown that inadequate vasculogenesis in systemic sclerosis (SSc) has been associated with an endothelial defect. We used a genetic lineage tracing model to investigate whether endothelial cells die or change phenotypically after fibrosis induction and whether signals released by cells of the innate immune system and in the blood of patients influence their commitment. We observed that in the lineage-tracing transgenic mice Cdh5-CreER^T2::R26R-EYFP, endothelial-derived cells (EdCs) underwent fibrosis after treatment with bleomycin, and EdCs retrieved from the lung showed expression of endothelial-to-mesenchymal transition (EndoMT) markers. Liposome-encapsulated clodronate was used to assess macrophage impact on EdCs. Clodronate treatment affected the number of alternatively activated macrophages in the lung, with upregulated expression of EndoMT markers in lung EdCs. Endothelial fate and function were investigated in vitro upon challenge with serum signals from SSc patients or released by activated macrophages. Sera of SSc patients with anti-Scl70 Abs, at higher risk of visceral organ fibrosis, induced EndoMT and jeopardized endothelial function. In conclusion, EdCs in SSc might be defective because of commitment to a mesenchymal fate, which is sustained by soluble signals in the patient's blood. Macrophages contribute to preserve the endothelial identity of precursor cells. Altered macrophage-dependent plasticity of EdCs could contribute to link vasculopathy with fibrosis.

Linear scleroderma "en coup de sabre" with extensive brain involvement-Clinicopathologic correlations and response to anti-Interleukin-6 therapy

Linear scleroderma “en coup de sabre” (LSES) variant is a cephalic subtype of localized scleroderma that can be associated with extracutaneous stigmata, such as epilepsy, dementia syndromes, as well as focal central nervous system neurologic deficits. While the pathophysiology of cutaneous linear scleroderma includes endothelial cell injury and up regulation of pro-fibrogenic pathways, the basis of LSES-associated neurologic complications is largely unknown. We report a patient with a history of LSES who developed intractable epilepsy and cognitive decline. Magnetic resonance imaging (MRI) of the brain exhibited numerous persistently enhancing brain lesions. Due to progressive neurologic deterioration over a period of 7 years, despite interventional therapy, a brain biopsy was performed. Neuropathologic analysis exhibited acute and chronic cortical ischemia associated with a small vessel lymphocytic vasculitis. Direct immunofluorescent studies showed C5b-9 and IgG deposition on endothelium while indirect immunofluorescent studies demonstrated reactivity of the patient’s serum with the microvasculature of the patient’s own brain tissue and generic human umbilical vein endothelial cells indicative of anti-endothelial cell antibodies. Therapy focusing on damaged endothelium was implemented. The interleukin-6 (IL-6) receptor inhibitor tocilizumab was used and the patient improved dramatically, likely reflecting the drug’s effect on the replenishment of endothelial progenitor cells.

Imbalanced serum levels of Ang1, Ang2 and VEGF in systemic sclerosis: Integrated effects on microvascular reactivity

INTRODUCTION AND AIM

Microangiopathy is a hallmark of systemic sclerosis (SSc). It is a progressive process from an early inflammatory and proangiogenic environment to insufficient microvascular repair with loss of microvessels. The exact underlying mechanisms remain ill-defined. Aim of the study was to investigate whether imbalanced angiopoietins/VEGF serum profile should be related in SSc to the altered microvascular reactivity characterized by aberrant angiogenesis and avascularity.

MATERIALS AND METHODS

Serum levels of Angiopoietin-1 (Ang1), Angiopoietin-2 (Ang2) and VEGF were measured by ELISA in 47 SSc patients and 27 healthy controls. Microvascular alterations were assessed by nailfold videocapillaroscopy (NVC).

RESULTS

Serum concentrations of Ang1 were significantly lower [mean (S.D.): 21516.04 (11,441.035) pg/ml], and Ang2 significantly increased [25,89.55 (934.225) pg/ml] in SSc as compared with the control group [Ang1: 28,457.08 (10,431.905) pg/ml; Ang2: 1556.23 (481.255) pg/ml, p < 0.01, respectively], whereas VEGF did not differ significantly. The ratios of Ang1/Ang2 and Ang1/VEGF were significantly lower in SSc patients (8.346 ± 4.523 and 95.17 ± 75.0, respectively) than in healthy subjects (17.612 ± 6.731 p < 0.000001 and 183.11 ± 137.73; p = 0.004]. Formation of giant capillaries with vascular leakage and collapse was associated with significant increase in VEGF and concomitant Ang1 deficiency. Capillary loss was related to significant increase in VEGF with respect to those with preserved capillary number (395.12 ± 256.27 pg/mL vs. 254.80 ± 213.61 pg/mL) whereas elevated Ang2 levels induced more advanced capillary damage as indicated by the presence of the "Late" NVC pattern.

CONCLUSIONS

We found that serum levels of Ang1, Ang2 and VEGF are differentially expressed in SSc and altered Ang1/Ang2 profile might underlay the aberrant angiogenesis in SSc despite increase in VEGF. For the first time we identified that significant deficiency of Ang1 might be involved in early capillary enlargement, followed by collapse and lack of stable newly-formed vessels in VEGF-enriched environment, whereas Ang2 levels seem to increase later in disease progression and advanced microvascular damage ("Late" NVC pattern).

Histone modifications underlie monocyte dysregulation in patients with systemic sclerosis, underlining the treatment potential of epigenetic targeting

BACKGROUND AND OBJECTIVE

Systemic sclerosis (SSc) is a severe autoimmune disease, in which the pathogenesis is dependent on both genetic and epigenetic factors. Altered gene expression in SSc monocytes, particularly of interferon (IFN)-responsive genes, suggests their involvement in SSc development. We investigated the correlation between epigenetic histone marks and gene expression in SSc monocytes.

METHODS

Chromatin immunoprecipitation followed by sequencing (ChIPseq) for histone marks H3K4me3 and H3K27ac was performed on monocytes of nine healthy controls and 14 patients with SSc. RNA sequencing was performed in parallel to identify aberrantly expressed genes and their correlation with the levels of H3K4me3 and H3K27ac located nearby their transcription start sites. ChIP-qPCR assays were used to verify the role of bromodomain proteins, H3K27ac and STATs on IFN-responsive gene expression.

RESULTS

1046 and 534 genomic loci showed aberrant H3K4me3 and H3K27ac marks, respectively, in SSc monocytes. The expression of 381 genes was directly and significantly proportional to the levels of such chromatin marks present near their transcription start site. Genes correlated to altered histone marks were enriched for immune, IFN and antiviral pathways and presented with recurrent binding sites for IRF and STAT transcription factors at their promoters. IFNα induced the binding of STAT1 and STAT2 at the promoter of two of these genes, while blocking acetylation readers using the bromodomain BET family inhibitor JQ1 suppressed their expression.

CONCLUSION

SSc monocytes have altered chromatin marks correlating with their IFN signature. Enzymes modulating these reversible marks may provide interesting therapeutic targets to restore monocyte homeostasis to treat or even prevent SSc.

Endothelial cell-specific activation of transforming growth factor-β signaling in mice induces cutaneous, visceral, and microvascular fibrosis

In this study, we tested the hypothesis that constitutive endothelial cell-specific activation of TGF-β signaling induces tissue fibrosis and vasculopathy resembling the characteristic fibrotic and vascular alterations of systemic sclerosis. Transgenic mice with inducible expression of a constitutively active TGF-β receptor I specifically in endothelial cells were generated by intercrossing mice harboring a constitutively active TGF-β receptor I with a mouse strain containing the endothelial cell-specific Cdh5 gene promoter directing the tamoxifen-inducible expression of the Cre-ER^T2 cassette. Administration of tamoxifen to these mice would result in constitutive TGF-β activation and signaling confined to endothelial lineage cells. The effects of constitutive TGF-β endothelial cell activation were assessed by histopathological examination of skin and various internal organs, tissue hydroxyproline analysis, and assessment of expression of myofibroblast differentiation and TGF-β signaling genes employing real-time PCR and immunohistochemical staining of lung vessels for endothelial- and myofibroblast-specific proteins. Constitutive TGFβ-1 signaling in endothelial cells resulted in cutaneous and visceral fibrosis with prominent fibrotic involvement of the lungs and severe perivascular and subendothelial fibrosis of small arterioles. A marked increase in the expression of fibrosis-associated genes and of genes indicative of myofibroblast activation was also found. Confocal microscopy of lung vessels showed evidence consistent with the induction of endothelial-to-mesenchymal transition (EndoMT). Taken together, our data indicate that transgenic mice with constitutive endothelial cell-specific activation of TGF-β signaling display severe cutaneous, pulmonary, and microvascular fibrosis resembling the fibrotic and microvascular alterations characteristic of systemic sclerosis.

Plasma endothelial microparticles reflect the extent of capillaroscopic alterations and correlate with the severity of skin involvement in systemic sclerosis

INTRODUCTION AND AIM

Endothelial microparticles (EMPs) are membrane-coated vesicles shed from endothelial cells and are considered markers of the endothelial state. It has been shown that total numbers of circulating EMPs are increased in patients with systemic sclerosis (SSc), but their clinical correlations have not yet been investigated in detail. We aimed to assess possible relationships between circulating EMPs and clinical as well as laboratory features among SSc patients with special attention to possible association with alteration in microvascular morphology objectified on nailfold videocapillaroscopy and clinical signs of microvascular complications.

MATERIALS AND METHODS

The study included 47 SSc patients and 27 age- and sex-matched healthy controls. EMPs were identified with flow cytometry after staining platelet-poor plasma with combinations of fluorescent cell-specific monoclonal antibodies (anti-CD31, -51, -42b, -62E and Annexin V). The following types of EMPs were evaluated: total EMPs (CD31+/CD42b-), activated EMPs (CD62E+/AnnV-,) and apoptotic EMPs (CD62E+/AnnV+ or CD51+). Clinical evaluation of patients was obtained, including nailfold videocapillaroscopy.

RESULTS

All types of EMPs were significantly elevated in SSc patients as compared with healthy controls. We found significant inverse correlation between severity of skin involvement and values of total EMPs (r=-0.32; p=0.02) and their levels tended to be lower in SSc patients with digital ulcers when compared to those without ischaemic skin lesions (p=0.09). Total EMPs and activated EMPs showed correlations with the number of ramified capillaries (r=-0.40 and r=0.37, respectively, p<0.05 for both). Moreover, total EMPs inversely correlated with the severity of capillary loss (r=-0.35, p<0.05) and their levels were significantly lower in patients with late NVC pattern with respect to those with early microangiopathy (p<0.05). On the other hand, active NVC pattern was characterized by strongly elevated levels of activated EMPs when compared to an early vascular alteration (p<0.05).

CONCLUSIONS

Our results suggest that quantity and phenotype of circulating EMPs might indicate on molecular vascular damage with endothelial dysfunction and to reflect progressive loss of capillaries consequencing in microvascular insufficiency in SSc patients.

Vascular Remodelling and Mesenchymal Transition in Systemic Sclerosis

Fibrosis of the skin and of internal organs, autoimmunity, and vascular inflammation are hallmarks of Systemic Sclerosis (SSc). The injury and activation of endothelial cells, with hyperplasia of the intima and eventual obliteration of the vascular lumen, are early features of SSc. Reduced capillary blood flow coupled with deficient angiogenesis leads to chronic hypoxia and tissue ischemia, enforcing a positive feed-forward loop sustaining vascular remodelling, further exacerbated by extracellular matrix accumulation due to fibrosis. Despite numerous developments and a growing number of controlled clinical trials no treatment has been shown so far to alter SSc natural history, outlining the need of further investigation in the molecular pathways involved in the pathogenesis of the disease. We review some processes potentially involved in SSc vasculopathy, with attention to the possible effect of sustained vascular inflammation on the plasticity of vascular cells. Specifically we focus on mesenchymal transition, a key phenomenon in the cardiac and vascular development as well as in the remodelling of injured vessels. Recent work supports the role of transforming growth factor-beta, Wnt, and Notch signaling in these processes. Importantly, endothelial-mesenchymal transition may be reversible, possibly offering novel cues for treatment.

Increased expression of NAPDH oxidase 4 in systemic sclerosis dermal fibroblasts: regulation by transforming growth factor β

OBJECTIVE

Systemic sclerosis (SSc) is characterized by severe and often progressive fibrosis of the skin and multiple internal organs. The mechanisms responsible for these alterations remain obscure, although excessive reactive oxygen species (ROS)-mediated oxidative stress has been implicated. NOX-4 is 1 of 7 isoforms of NADPH oxidase responsible for the generation of ROS. The purpose of this study was to examine NOX-4 expression in skin and cultured dermal fibroblasts from SSc patients and to examine its regulation by transforming growth factor β1 (TGFβ1).

METHODS

NOX-4 was assessed in normal and SSc skin by immunohistologic analysis and in normal and SSc cultured dermal fibroblasts by quantitative polymerase chain reaction analysis, fluorescence microscopy, and Western blotting. ROS levels were assessed by fluorescence measurement of H2 O2 production. Specific kinase inhibitors were used to study the TGFβ1 signaling involved in NOX-4 stimulation. NOX-4 inhibition/down-regulation was induced with a selective NOX-4 small-molecule inhibitor and NOX-4 small interfering RNA (siRNA).

RESULTS

In contrast with normal skin fibroblasts, those from SSc skin showed intense NOX-4 staining. Cultured SSc fibroblasts displayed increased NOX-4 expression. TGFβ1 caused potent NOX-4 protein and messenger RNA stimulation in normal and SSc fibroblasts, which was mediated by the protein kinase Cδ (PKCδ) and Smad2/3 pathways. NOX-4 knockdown in SSc fibroblasts reduced the production of ROS and lowered the expression of type I collagen.

CONCLUSION

NOX-4 expression and production were found to be constitutively elevated in SSc skin and cultured SSc dermal fibroblasts. TGFβ1 stimulated NOX-4 expression in normal and SSc fibroblasts through PKCδ and Smad2/3 signaling pathways. A small-molecule NOX-4 inhibitor decreased collagen and fibronectin production by normal and SSc fibroblasts, and NOX-4 siRNA knockdown reduced ROS and collagen production by SSc fibroblasts. These results demonstrate the involvement of NOX-4 in SSc-associated fibrosis and indicate NOX-4 inhibitors as novel therapeutic approaches for SSc.

[Large vessels vasculopathy in systemic sclerosis]

Vasculopathy in systemic sclerosis is a severe, in many cases irreversible, manifestation that can lead to amputation. While the classical clinical manifestations of the disease have to do with the involvement of microcirculation, proximal vessels of upper and lower limbs can also be affected. This involvement of large vessels may be related to systemic sclerosis, vasculitis or atherosclerotic, and the differential diagnosis is not easy. To conduct a proper and early diagnosis, it is essential to start prompt appropriate treatment. In this review, we examine the involvement of large vessels in scleroderma, an understudied manifestation with important prognostic and therapeutic implications.

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.

Macro- and microvascular disease in systemic sclerosis

Vasculopathy is common in patients with connective tissue disease and can be directly implicated in the pathogenesis of the disease. Systemic sclerosis is an auto-immune multiorgan connective tissue disorder characterized by fibrosis of the skin and visceral organs and vascular disease. Micro- and macro-vessels are a direct target of the disease. In this review, we present the various clinical manifestations of the vasculopathy that can be present in SSc patients, and then discuss the various aspects of the pathophysiology of the vascular disorders.

DNA methylation similarities in genes of black South Africans with systemic lupus erythematosus and systemic sclerosis

Background

Systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) are systemic autoimmune connective tissue diseases that share overlapping clinico-pathological features. It is highly probable that there is an overlap in epigenetic landscapes of both diseases. This study aimed to identify similarities in DNA methylation changes in genes involved in SLE and SSc. Global DNA methylation and twelve genes selected on the basis of their involvement in inflammation, autoimmunity and/or fibrosis were analyzed using PCR arrays in three groups, each of 30 Black South Africans with SLE and SSc, plus 40 healthy control subjects.

Results

Global methylation in both diseases was significantly lower (<25 %) than in healthy subjects (>30 %, p = 0.0000001). In comparison to healthy controls, a similar gene-specific methylation pattern was observed in both SLE and SSc. Three genes, namely; PRF1, ITGAL and FOXP3 were consistently hypermethylated while CDKN2A and CD70 were hypomethylated in both diseases. The other genes (SOCS1, CTGF, THY1, CXCR4, MT1-G, FLI1, and DNMT1) were generally hypomethylated in SLE whereas they were neither hyper- nor hypo-methylated in SSc.

Conclusions

SSc and SLE patients have a higher global hypomethylation than healthy subjects with specific genes being hypomethylated and others hypermethylated. The majority of genes studied were hypomethylated in SLE compared to SSc. In addition to the commonly known hypomethylated genes in SLE and SSc, there are other hypomethylated genes (such as MT-1G and THY-1) that have not previously been investigated in SLE and SSc though are known to be hypermethylated in cancer.

The significance of macrophage polarization subtypes for animal models of tissue fibrosis and human fibrotic diseases

The systemic and organ-specific human fibrotic disorders collectively represent one of the most serious health problems world-wide causing a large proportion of the total world population mortality. The molecular pathways involved in their pathogenesis are complex and despite intensive investigations have not been fully elucidated. Whereas chronic inflammatory cell infiltration is universally present in fibrotic lesions, the central role of monocytes and macrophages as regulators of inflammation and fibrosis has only recently become apparent. However, the precise mechanisms involved in the contribution of monocytes/macrophages to the initiation, establishment, or progression of the fibrotic process remain largely unknown. Several monocyte and macrophage subpopulations have been identified, with certain phenotypes promoting inflammation whereas others display profibrotic effects. Given the unmet need for effective treatments for fibroproliferative diseases and the crucial regulatory role of monocyte/macrophage subpopulations in fibrogenesis, the development of therapeutic strategies that target specific monocyte/macrophage subpopulations has become increasingly attractive. We will provide here an overview of the current understanding of the role of monocyte/macrophage phenotype subpopulations in animal models of tissue fibrosis and in various systemic and organ-specific human fibrotic diseases. Furthermore, we will discuss recent approaches to the design of effective anti-fibrotic therapeutic interventions by targeting the phenotypic differences identified between the various monocyte and macrophage subpopulations.

Interleukin-17A promotes functional activation of systemic sclerosis patient-derived dermal vascular smooth muscle cells by extracellular-regulated protein kinases signalling pathway

INTRODUCTION

Dermal vascular smooth muscle cells (DVSMCs) are important for vascular wall fibrosis in microangiopathy of systemic sclerosis (SSc). T helper 17 cell-associated cytokines, particularly interleukin-17A (IL-17A), have been demonstrated to play a role in the pathogenesis of SSc. However, the effect of IL-17A on the DVSMCs in microangiopathy of SSc has not been established. In the present study, we investigated the effect of IL-17A on the SSc patient-derived DVSMCs.

METHODS

DVSMCs from patients with SSc and healthy subjects were incubated using IL-17A or serum derived from patients with SSc. Subsequently, the proliferation, collagen synthesis and secretion, and migration of DVSMCs were analysed using a cell counting kit-8 (CCK-8), dual-luciferase reporter assay, real-time reverse transcription-polymerase chain reaction (RT-PCR), Western blot, enzyme-linked immunosorbent assay (ELISA) and transwell assay. The protein phosphorylation of signalling pathways in the process of IL-17A-mediated DVSMC activation was investigated and validated by specific signalling pathway inhibitor.

RESULTS

IL-17A and serum from patients with SSc could promote the proliferation, collagen synthesis and secretion, and migration of DVSMCs. IL-17A neutralising antibody could inhibit the IL-17A-induced activation of DVSMCs. Additionally, IL-17A induced the activation of extracellular-regulated protein kinases 1/2 (ERK1/2) in DVSMCs, and ERK1/2 inhibitor could block the IL-17A-elicited activation of DVSMCs.

CONCLUSIONS

Our results suggested that IL-17A derived from patients with SSc might induce the proliferation, collagen synthesis and secretion, and migration of DVSMCs via ERK1/2 signalling pathway, raising the likelihood that IL-17A and ERK1/2 might be promising therapeutic targets for the treatment of SSc-related vasculopathy.

Anti-endothelial cell antibodies in connective tissue diseases associated with pulmonary arterial hypertension

OBJECTIVE

To investigate the prevalence of anti-endothelial cell antibodies (AECA) in connective tissue diseases (CTD) associated with pulmonary arterial hypertension (PAH) and to corroborate the pathologic function of AECA in PAH-associated CTDs.

METHODS

AECA were detected by cellular enzyme-linked immunosorbent assay (ELISA) in sera of 19 PAH-associated CTD patients, 22 CTD patients without PAH involvement, and 20 age- and sex-matched healthy individuals as controls. Using IgG purified from the sera of AECA-positive, AECA-negative, and healthy subjects, the effects of AECA on the expression of ICAM-1 and the chemokine regulated upon activation normal T-cell expressed and secreted (RANTES) in cultured endothelial cells were also evaluated.

RESULTS

A total of 12 of the 19 (63.2%) CTD patients with PAH, 9 of the 22 (40.9%) CTD patients without PAH, and 1 of the 20 (5%) healthy controls were positive for AECA, which were calculated as ELISA ratio (ER) values. ER values in PAH-associated CTD patients were significantly higher than those with CTD without PAH (3.68±2.05 versus 1.67±1.07, P<0.001). IgG purified from AECA-positive sera induced a significantly increased level of ICAM-1 expression after 48 h incubation (795.2±32.5 pg/mL) compared with AECA-negative or healthy control IgG (231.5±27.1 and 192.8±33.4 pg/mL, respectively; P<0.001). In addition, RANTES production by cultured human pulmonary arterial endothelial cells (HPAECs) increased in both a time- and concentration-dependent manner in response to incubation with purified AECA-positive IgG.

CONCLUSIONS

AECA could be involved in CTD and might participate in the pathogenesis of PAH-associated CTD.

Oxidative stress elicits platelet/leukocyte inflammatory interactions via HMGB1: a candidate for microvessel injury in sytemic sclerosis

AIMS

An abnormal generation of reactive oxygen species (ROS) is thought to contribute to systemic sclerosis (SSc), fostering autoimmunity, fibrosis, and vascular inflammation. The function of the prototypic damage-associated molecular pattern, high mobility group box 1 (HMGB1), depends on its redox status. Here we investigate whether oxidative stress regulates the cross-talk between leukocytes and platelets via HMGB1, thus contributing to vessel inflammation in SSc.

RESULTS

The oxidation of HMGB1 amplified its ability to activate neutrophils, as detected assessing the redistribution of primary granule molecules and the transactivation of the β2 integrin chain CD18. Activated platelets are a source of bioactive HMGB1 and via P-selectin stimulated neutrophils to generate ROS. Oxidized extracellular HMGB1, soluble or associated to platelet membrane or to platelet-derived microparticles (PDμPs), further increased leukocyte activation. Leukocyte activation abated in the presence of inhibitors of HMGB1 or of catalase, which catalyzes the dismutation of hydrogen peroxide into water and molecular oxygen. The redistribution of the content of primary granules and the transactivation of β2 integrins characterized blood leukocytes of SSc patients and membrane HMGB1 was significantly higher in patients with pulmonary hypertension or with diffuse SSc. HMGB1(+) microparticles (μPs) purified from SSc patients, but not HMGB1(-) μPs purified from control subjects, activated in vitro healthy neutrophils, and HMGB1 inhibitors reversed the effects of μPs.

INNOVATION AND CONCLUSION

ROS dramatically increase the ability of extracellular HMGB1 to activate blood leukocytes. This event might contribute to maintain the microvascular injury of patients with SSc.

Overlapping gene expression profiles indicative of antigen processing and the interferon pathway characterize inflammatory fibrotic skin diseases

Inflammatory fibrotic disorders have been of high interest both for dermatologists and rheumatologists. Although the phenotypic end stage of this group of diseases is ultimately the same, namely fibrosis, patients present with different clinical features and are often treated with distinct therapeutic modalities. This review addresses whether there is evidence for different underlying molecular pathways in the various inflammatory fibrotic diseases such as localized scleroderma, pediatric lichen sclerosus, adult lichen sclerosus, eosinophilic fasciitis and systemic sclerosis. To investigate this, a large number of gene expression microarray studies performed on skin or fibroblasts from patients with these aforementioned diseases were described, (re-)analysed, and compared. As suspected by the heterogeneous phenotype, most diseases showed unique gene expression features. Intriguingly, a clear overlap was observed between adult and pediatric lichen sclerosus and localized scleroderma, in antigen processing and the interferon pathway. Delineating the cause and consequence of these pathways may generate novel tools to better characterize and more effectively treat these patients.

Novel investigational agents for the treatment of scleroderma

INTRODUCTION

The purpose of this article is to highlight novel therapies that are being used in scleroderma (SSc). Therapeutic interventions in SSc generally target at least one of three ongoing biological processes characteristic of the disease: vasculopathy, autoimmunity and tissue fibrosis. Treatment decisions in SSc are determined by the level of disease activity and the degree of specific organ involvement. Traditional therapy has primarily focused on organ-specific management without clear evidence of overall disease modification.

AREAS COVERED

The authors provide a review of a variety of agents, which are already used for other autoimmune diseases, that are now being used to treat active SSc skin or lung disease, including rituximab, tocilizumab and IVIG. Several agents studied in vitro and in animal models of fibrosis have shown promise, including bortezomib, LPA-1 antagonists, anti-CCN2 therapy, anti-IL-13 and thrombin antagonists. The authors also provide details on targeting intracellular molecular pathways and matricellular proteins, which is another novel area of investigation.

EXPERT OPINION

Combination therapy may be necessary to control the complex biological network active in SSc. Most of the current evidence that suggest benefit of these agents is based on small population studies. Ultimately well-designed clinical trials are required to define the role of these agents in treating SSc.

Role of endothelial to mesenchymal transition in the pathogenesis of the vascular alterations in systemic sclerosis

The pathogenesis of Systemic Sclerosis (SSc) is extremely complex, and despite extensive studies, the exact mechanisms involved are not well understood. Numerous recent studies of early events in SSc pathogenesis have suggested that unknown etiologic factors in a genetically receptive host trigger structural and functional microvascular endothelial cell abnormalities. These alterations result in the attraction, transmigration, and accumulation of immune and inflammatory cells in the perivascular tissues, which in turn induce the phenotypic conversion of endothelial cells and quiescent fibroblasts into activated myofibroblasts, a process known as endothelial to mesenchymal transition or EndoMT. The activated myofibroblasts are the effector cells responsible for the severe and frequently progressive fibrotic process and the fibroproliferative vasculopathy that are the hallmarks of SSc. Thus, according to this hypothesis the endothelial and vascular alterations, which include the phenotypic conversion of endothelial cells into activated myofibroblasts, play a crucial role in the development of the progressive fibrotic process affecting skin and multiple internal organs. The role of endothelial cell and vascular alterations, the potential contribution of endothelial to mesenchymal cell transition in the pathogenesis of the tissue fibrosis, and fibroproliferative vasculopathy in SSc will be reviewed here.

Progression of Nailfold Microvascular Damage and Antinuclear Antibody Pattern in Systemic Sclerosis

Objective.

This study evaluates possible correlations between the pattern of antinuclear antibodies (ANA) on indirect immunofluorescence (IIF) testing and nailfold microangiopathy stage (early, active, and late stage) in systemic sclerosis (SSc). Patients with SSc were followed prospectively to monitor progression of microvascular damage.

Methods.

The ANA pattern on IIF was searched in 42 patients with SSc showing an early pattern of nailfold microangiopathy at baseline, and was followed using nailfold videocapillaroscopy (NVC) for a median time of 91 months.

Results.

Among patients whose microangiopathy showed a rapid progression from early to late pattern on NVC, the IIF pattern was fine-speckled + nucleolar (Scl-70+) in 44%, centromeric in 33%, nucleolar in 11%, and homogeneous in 11% of patients with SSc. Antitopoisomerase I antibodies were significantly more frequent (57%) in patients with late pattern of microangiopathy on NVC. The median time of progression from early to active disease was significantly lower in patients with both fine-speckled + nucleolar and nucleolar ANA positivity. The severity of microangiopathy was higher in patients with the nucleolar pattern on IIF. Patients already showing a slight reduction of capillary number at baseline were likely to have either the nucleolar or the fine-speckled + nucleolar pattern on IIF. Of note, 37% of patients still showing the early microangiopathy pattern on NVC at the end of the followup were ANA-negative.

Conclusion.

ANA-negative patients with SSc display a slower progression of nailfold microangiopathy characterized by the early pattern on NVC. Progression to the late NVC pattern (more advanced stage of microvascular damage) seems to be associated with a different autoantibody pattern on IIF (fine-speckled + nucleolar pattern being the most prevalent).

Muscle-fiber transdifferentiation in an experimental model of respiratory chain myopathy

Introduction

Skeletal muscle fiber composition and muscle energetics are not static and change in muscle disease. This study was performed to determine whether a mitochondrial myopathy is associated with adjustments in skeletal muscle fiber-type composition.

Methods

Ten rats were treated with zidovudine, an antiretroviral nucleoside reverse transcriptase inhibitor that induces a myopathy by interfering with mitochondrial functions. Soleus muscles were examined after 21 weeks of treatment. Ten untreated rats served as controls.

Results

Zidovudine induced a myopathy with mitochondrial DNA depletion, abnormalities in mitochondrial ultrastructure, and reduced cytochrome c oxidase activity. Mitochondrial DNA was disproportionally more diminished in type I compared with type II fibers, whereas atrophy predominated in type II fibers. Compared with those of controls, zidovudine-exposed soleus muscles contained an increased proportion (256%) of type II fibers, whereas neonatal myosin heavy chains remained repressed, indicating fiber-type transformation in the absence of regeneration. Microarray gene-expression analysis confirmed enhanced fast-fiber isoforms, repressed slow-fiber transcripts, and reduced neonatal fiber transcripts in the mitochondrial myopathy. Respiratory chain transcripts were diminished, whereas the enzymes of glycolysis and glycogenolysis were enhanced, indicating a metabolic adjustment from oxidative to glycolytic capacities. A coordinated regulation was found of transcription factors known to orchestrate type II fiber formation (upregulation of MyoD, Six1, Six2, Eya1, and Sox6, and downregulation of myogenin and ERRγ).

Conclusions

The type I to type II fiber transformation in mitochondrial myopathy implicates mitochondrial function as a new regulator of skeletal muscle fiber type.

The pathogenesis, diagnosis and treatment of Raynaud phenomenon

The past 10 years have seen the publication of results from several multicentre clinical trials in primary and systemic sclerosis (SSc)-related Raynaud phenomenon. The publication of these studies has occurred as a result of new insights into the pathogenesis of Raynaud phenomenon, which are directing new treatment approaches, and increased international collaboration between clinicians and scientists. Although the pathogenesis of Raynaud phenomenon is complex, abnormalities of the blood vessel wall, of neural control mechanisms and of intravascular (circulating) factors are known to interact and contribute. Key players relevant in drug development include nitric oxide, endothelin-1, alpha adrenergic receptor activation, abnormal signal transduction in vascular smooth muscle, oxidative stress and platelet activation. The main advances in diagnosis have been a clearer understanding of autoantibodies and of abnormal nailfold capillary patterns as independent predictors of SSc, and widespread use and increased availability of capillaroscopy. The ultimate aim is to translate the advances made in the pathophysiology and early diagnosis into development of treatments to prevent and reverse digital vascular dysfunction and injury. This Review provides an update of the pathogenesis, diagnosis and treatment of Raynaud phenomenon. Current and future treatment approaches are discussed, and some key unanswered questions are highlighted.

Baseline vWF factor predicts the development of elevated pulmonary artery pressure in systemic sclerosis

Objectives. This study aims to examine the utility of von Willebrand factor (vWF) as a biomarker in lcSSc, in particular the ability of vWF to predict the future development of disease manifestations in this disease.

Methods. vWFAg concentrations were measured in the serum of patients with lcSSc at baseline and at 3 years, during the QUINs trial [Prevention of Vascular Damage in Scleroderma with Angiotensin-Converting Enzyme (ACE) Inhibition]. %DL_CO, %KCO, %FVC, pulmonary artery pressure (PAP) estimation by echocardiography, Raynaud’s attack frequency, Raynaud’s severity, digital ulcer frequency, urinary protein excretion, estimated glomerular filtration rate (eGFR), modified Rodnan skin score and Medsger disease activity score were also measured at baseline and 3 years.

Results. Baseline serum vWF concentrations were related to concurrent Medsger disease activity score, %DL_CO, %FVC, urinary protein excretion, eGFR and PAP >30 mmHg. In logistic regression models, baseline serum vWF concentrations were able to predict the future development of elevated PAP by echocardiography (PAP >40 mmHg, P = 0.001).

Conclusions. Pulmonary artery hypertension is a life-threatening complication of lcSSc. vWF is a marker of endothelial cell activation. Raised serum concentrations of vWF in lcSSc increase the risk of developing subsequent elevation in PAP. Therefore screening patients with lcSSc for vWF may identify a group at risk of developing PAH. These patients could potentially be targeted with agents that stabilize the endothelium, e.g. statins.

Dendritic cells: novel players in fibrosis and scleroderma

Dendritic cells are professional antigen-presenting cells that are most studied for their function in mediating T-cell tolerance and T-cell activation. In addition, recent evidence indicates that dendritic cells can regulate the vasculature and function of fibroblast-type cells. The potential contribution of dendritic cells to scleroderma and fibrosis is not well-understood. In this article, we review recent studies as well as describe our own ongoing work that points toward a role for dendritic cells in scleroderma and fibrosis.

The many faces of interleukin-6: the role of IL-6 in inflammation, vasculopathy, and fibrosis in systemic sclerosis

Interleukin-6 is currently attracting significant interest as a potential therapeutic target in systemic sclerosis (SSc). In this paper, the biology of interleukin-6 is reviewed, and the evidence for interleukin-6 dysregulation in SSc is explored. The role of inteleukin-6 classical and trans signalling pathways in SSc relevant phenomena such as chronic inflammation, autoimmunity, endothelial cell dysfunction, and fibrogenesis is discussed. The existing evidence that interventions designed to block interleukin-6 signalling are of therapeutic relevance in SSc is evaluated.

Vascular involvement in systemic sclerosis (scleroderma)

Systemic sclerosis (SSc) is an acquired multiorgan connective tissue disease with variable mortality and morbidity dictated by clinical subset type. The etiology of the basic disease and pathogenesis of the systemic autoimmunity, fibrosis, and fibroproliferative vasculopathy are unknown and debated. In this review, the spectrum of vascular abnormalities and the options currently available to treat the vascular manifestations of SSc are discussed. Also discussed is how the hallmark pathologies (ie, how autoimmunity, vasculopathy, and fibrosis of the disease) might be effected and interconnected with modulatory input from lysophospholipids, sphingosine 1-phosphate, and lysophosphatidic acid.

Bosentan in clinical practice for treating digital and other ischemic ulcers in Spanish patients with systemic sclerosis: IBER-DU cohort study

OBJECTIVE

To describe treatment outcomes and safety experience with bosentan in patients with systemic sclerosis (SSc) and digital ulcers (DU), in a clinical setting in Spain.

METHODS

This was a multicenter, noninterventional retrospective cohort study. Data were collected retrospectively from patients with DU, with or without pulmonary arterial hypertension (PAH), who were initiating bosentan therapy in 2003 (n = 26) or 2004 (n = 41) and followed until May 2005. Data were obtained from centers prescribing bosentan. Relevant measures included number of DU, occurrence of new DU, overall DU clinical status (improved, stabilized, worsened), and bosentan-associated adverse events.

RESULTS

Sixty-seven patients with SSc and DU or other ulcers were included. PAH was also present in 12 patients (18%). At the start of bosentan treatment, the median number of DU per patient was 3.0. The median change in number of DU was -3.6 and -5.0 at 12 and 24 months, respectively. Sixty-eight percent of the patients did not develop any new DU at 12 months. DU clinical status was reported at 12 months for 22 patients: 18 patients (81.8%) improved and 4 (18.2%) stabilized. The median treatment duration was 13.0 months. The main adverse event was increase of aminotransferase, observed in 5 patients (7%), leading to discontinuation of treatment in 3 patients (4.4%).

CONCLUSION

Previously reported results of bosentan efficacy in DU management are reproducible in clinical practice. This efficacy is maintained in the longterm followup. Bosentan treatment was well tolerated and adverse events were comparable with those observed in previous reports.

Endothelial activation and apoptosis mediated by neutrophil-dependent interleukin 6 trans-signalling: a novel target for systemic sclerosis?

Objectives

Systemic sclerosis (SSc) is a connective tissue disease associated with significant morbidity and mortality and generally inadequate treatment. Endothelial cell activation and apoptosis are thought to be pivotal in the pathogenesis of this disease, but the mechanisms that mediate this remain unknown.

Methods

Human dermal microvascular endothelial cells were cultured with healthy control neutrophils in the presence of 25% healthy control or SSc serum for 24 h. Apoptosis was measured by annexin V-FITC binding and endothelial cell activation was measured using an allophycocyanin-conjugated E-selectin antibody. Fluorescence was quantified and localised using confocal microscopy.

Results

SSc serum resulted in significantly increased apoptosis (p=0.006) and E-selectin expression (p=0.00004) in endothelial cells compared with control serum, effects that were critically dependent on the presence of neutrophils. Recombinant interleukin 6 (IL-6) reproduced these findings. Immunodepletion of IL-6 and the use of an IL-6 neutralising antibody decreased the effect of SSc serum on E-selectin expression. Soluble gp130, which specifically blocks IL-6 trans-signalling, negated the effect of SSc serum on both E-selectin expression and apoptosis.

Conclusions

SSc serum induces endothelial cell activation and apoptosis in endothelial cell-neutrophil co-cultures, mediated largely by IL-6 and dependent on the presence of neutrophils. Together with other pathologically relevant effects of IL-6, these data justify further exploration of IL-6 as a therapeutic target in SSc.

Perivascular T-cell infiltration leads to sustained pulmonary artery remodeling after endothelial cell damage

Pulmonary hypertension is a vascular proliferative disease characterized by pulmonary artery remodeling because of dysregulated endothelial and smooth muscle cell proliferation. Although the role of inflammation in the development of the disease is not well-defined, plexogenic lesions in human disease are characterized by perivascular inflammation composed, in part, of T cells. We explored the role of T-cell infiltration on pulmonary vascular remodeling after endothelial cell damage. We induced endothelial cell damage using monocrotaline and isolated the role of T cells by using Rag1(tm1Mom) mice and performing adoptive T-cell transfer. We found that monocrotaline causes pulmonary vascular endothelial cell injury followed by a perivascular inflammatory response. The infiltration of inflammatory cells primarily involves CD4(+) T cells and leads to the progressive muscularization of small (<30 μm) arterioles. Pulmonary vascular proliferative changes were accompanied by progressive and persistent elevations in right ventricular pressure and right ventricular hypertrophy. Supporting the central role of CD4(+) T cells in the inflammatory response, Rag1(tm1Mom) (Rag1(-/-)) mice, which are devoid of T and B cells, were protected from the development of vascular injury when exposed to monocrotaline. The introduction of T cells from control mice into Rag1(-/-) mice reproduced the vascular injury phenotype. These data indicate that after endothelial cell damage, CD4(+) T-cell infiltration participates in pulmonary vascular remodeling. This finding suggests that a CD4(+) T-cell immune response may contribute to the pathogenesis of inflammatory vascular lesions seen in some forms of pulmonary hypertension.

Systemic vasculopathy with altered vasoreactivity in a transgenic mouse model of scleroderma

Introduction

Vasculopathy, including altered vasoreactivity and abnormal large vessel biomechanics, is a hallmark of systemic sclerosis (SSc). However, the pathogenic link with other aspects of the disease is less clear. To assess the potential role of transforming growth factor beta (TGF-β) overactivity in driving these cardiovascular abnormalities, we studied a novel transgenic mouse model characterized by ligand-dependent activation of TGF-β signaling in fibroblasts.

Methods

The transgenic mouse strain Tβ RIIΔk-fib is characterized by balanced ligand-dependent upregulation of TGF-β signaling. Aortic and cardiac tissues were examined with histologic, biochemical, and isolated organ bath studies. Vascular and perivascular architecture was examined by hematoxylin and eosin (H&E) and special stains including immunostaining for TGF-β1 and phospho-Smad2/3 (pSmad2/3). Confirmatory aortic smooth muscle cell proliferation, phenotype, and functional assays, including signaling responses to exogenous TGF-β and endothelin-1, were performed. Aortic ring contractile responses to direct and receptor-mediated stimulation were assessed.

Results

Aortic ring contractility and relaxation were diminished compared with wild-type controls, and this was associated with aortic adventitial fibrosis confirmed histologically and with Sircol assay. TGF-β1 and pSmad 2/3 expression was increased in the adventitia and smooth muscle layer of the aorta. Aortic smooth muscle cells from transgenic animals showed significant upregulation of TGF-β- responsive genes important for cytoskeletal function, such as transgelin and smoothelin, which were then resistant to further stimulation with exogenous TGF-β1. These cells promoted significantly more contraction of free floating type I collagen lattices when compared with the wild-type, but were again resistant to exogenous TGF-β1 stimulation. Aortic ring responses to receptor-mediated contraction were reduced in the transgenic animals. Specifically, bosentan reduced endothelin-mediated contraction in wild-type animals, but had no effect in transgenic animals, and endothelin axis gene expression was altered in transgenic animals. Transgenic mice developed cardiac fibrosis.

Conclusions

The histologic, biochemical, and functional phenotype of this transgenic mouse model of scleroderma offers insight into the altered biomechanical properties previously reported for large elastic arteries in human SSc and suggests a role for perturbed TGF-β and endothelin activity in this process.

Junctional adhesion molecule-A is abnormally expressed in diffuse cutaneous systemic sclerosis skin and mediates myeloid cell adhesion

OBJECTIVE

To investigate the role of junctional adhesion molecule-A (JAM-A) in the pathogenesis of systemic sclerosis (SSc).

METHODS

Biopsy specimens from proximal and distal arm skin and serum were obtained from patients with SSc and normal volunteers. To determine the expression of JAM-A on SSc dermal fibroblasts and in SSc skin, cell surface ELISAs and immunohistology were performed. An ELISA was designed to determine the amount of soluble JAM-A (sJAM-A) in serum. Myeloid U937 cell-SSc dermal fibroblast and skin adhesion assays were performed to determine the role of JAM-A in myeloid cell adhesion.

RESULTS

The stratum granulosum and dermal endothelial cells (ECs) from distal arm SSc skin exhibited significantly decreased expression of JAM-A in comparison with normal volunteers. However, sJAM-A was increased in the serum of patients with SSc compared with normal volunteers. Conversely, JAM-A was increased on the surface of SSc compared with normal dermal fibroblasts. JAM-A accounted for a significant portion of U937 binding to SSc dermal fibroblasts. In addition, JAM-A contributed to U937 adhesion to both distal and proximal SSc skin.

CONCLUSIONS

JAM-A expression is dysregulated in SSc skin. Decreased expression of JAM-A on SSc ECs may result in a reduced response to proangiogenic basic fibroblast growth factor. Increased JAM-A expression on SSc fibroblasts may serve to retain myeloid cells, which in turn secrete angiogenic factors.

Biomarkers in systemic sclerosis

Systemic sclerosis is an autoimmune inflammatory disorder of unknown etiologycharacterized b y pronounced fibroproliferative alterations in the microvasculature, and frequent cellular and humoral immunity abnormalities, culminating in a severe and often progressive fibrotic process. Numerous biomarkers reflecting the three main pathogenetic mechanisms in systemic sclerosis have been described; however, aside from several disease-specific autoantibodies, other biomarkers have not been thoroughly validated and require further study. Thus, there is an unmet need for validated biomarkers for diagnosis, disease classification, and evaluation of organ involvement and therapeutic response in systemic sclerosis.

Mechanisms of vascular damage in systemic sclerosis

Although being classified as autoimmune connective tissue disease, dominant components of the pathophysiology of systemic sclerosis (SSc) consists of mechanisms of vascular damage, which can occur early in the course of the disease. Amongst them are abnormal vasoreactivity, hypoxia, insufficient neoangiogenesis and direct damage of vascular and perivascular cells. They result in a decreased capillary blood flow, and subsequently in clinically overt symptoms such as Raynaud's syndrome and fingertip ulcers. In addition, in active disease vascular pathology can affect various other organs, predominantly the lung, the kidney, the heart but also the gastrointestinal tract. Vascular pathology contributes also significantly to overall morbidity and mortality in SSc patients and reduces life expectancy by at least a decade. Fortunately, molecular biology has revealed a number of underlying pathways on the cellular and subcellular levels, including key factors of the aberrant function of (peri)vascular cells and autoimmune effector cells, the dysregulation of vasoconstrictive molecules and their receptors, the upregulation of intracellular signaling kinases and the altered balance of hypoxia-induced vascular growth factors. This increasing knowledge of vascular pathology in SSc has also resulted in novel therapeutic approaches ranging from endothelin antagonists to application of progenitor cells to counteract this aberrant vascular pathology and to support the repair of the dysfunctional vasculature.

Lymphatic and blood vessels in scleroderma skin, a morphometric analysis

Vascular involvement is frequent in systemic sclerosis, but the role of the lymphatic vasculature is poorly known. Our aim was to evaluate lymphatic vessels in systemic sclerosis skin lesions. We studied skin forearm biopsies of 9 patients with systemic sclerosis and 7 age-matched controls. Lymphatic vessels were labeled with the monoclonal antibody D2-40 and blood vessels with a polyclonal antibody to von Willebrand Factor. All blood and lymphatic vessels present in each section were counted and total area, inner luminal area, and shape factors were measured. The number of blood and lymphatic vessels in papillary dermis was greater and their diameter lower than in reticular dermis both in systemic sclerosis and controls. In the reticular dermis, the number of lymphatic vessels was markedly reduced in systemic sclerosis (4.9 ± 1.1 μm⁻² versus 8.9 ± 1.2 μm⁻²P = .03), and a similar trend was observed in papillary dermis (8.4 ± 3.7 μm⁻² versus 8.1 ± 5.3 μm⁻²). Interestingly, the number of periglandular lymphatics in systemic sclerosis was not different from controls. The inner luminal area (possibly indicating compensatory dilation) of lymphatic vessels, particularly the periglandular ones, was greater in systemic sclerosis than in controls. No differences were observed in the number of blood vessels, but the percentage of blood vessel profiles (without lumen) was significantly less in systemic sclerosis both in papillary and in reticular dermis. In conclusion, our data show that skin lesions in systemic sclerosis are characterized by a selective rarefaction of lymphatic vasculature that spares periglandular vessels and that might have a pathogenic role in the evolution and in the clinical manifestations of the disease.

Bilateral idiopathic avascular necrosis of the scaphoid

Whereas avascular necrosis of the scaphoid after a fracture is well-documented, idiopathic avascular necrosis of the scaphoid (Preiser’s disease) is rare. Little is known of the aetiology of the condition and even less about the best course of management. We describe a rare case of bilateral Preiser’s disease. Possible aetiological factors and a summary of the current concepts of management are discussed.