Hyperplasia of dermal microvascular pericytes in scleroderma*

TGFβ-mediated inhibition of hypodermal adipocyte progenitor differentiation promotes wound-induced skin fibrosis

Aberrant activation of dermal fibroblasts during wound healing often leads to debilitating fibrotic changes in the skin, such as scleroderma and keloids. However, the underlying cellular and molecular mechanisms remain elusive. Here, we established a wound-induced skin fibrosis (WISF) mouse model in mature adult mice, characterised by excessive deposition of collagen bundles, loss of dermal adipocytes, and enrichment of DPP4+Ly6A+THY1+ hypodermal interstitial adipocyte progenitors (HI-APs) and pericytes, resembling human fibrotic skin diseases. This WISF model exhibited an age-dependent gain of fibrotic characteristics, contrasting with the wound-induced hair neogenesis observed in younger mice. Through comprehensive analyses of the WISF, we delineated a trajectory of fibroblast differentiation that originates from HI-APs. These progenitors highly expressed several extracellular matrix (ECM) genes and exhibited a TGFβ pathway signature. TGFβ was identified as the key signal to inhibit the adipogenic potential and maintain the fibrogenic potential of dermal APs. Additionally, administering a TGFβ receptor inhibitor to wound scar reduced the abundance of ECM-producing APs. Finally, analysis of human scleroderma skin tissues revealed a negative correlation between the expression of AP-, ECM-, and TGFβ pathway-related genes and PPARG. Overall, this study establishes a wound-induced skin fibrosis mouse model and demonstrates that TGFβ-mediated blockage of HI-AP differentiation is crucial for driving fibrotic pathology. Targeting HI-APs and adipogenesis may provide novel avenues for developing disease-modifying therapies for fibrotic skin diseases.

Transcriptomic characterization of lung pericytes in systemic sclerosis-associated pulmonary fibrosis

Systemic sclerosis (SSc) is a chronic disease characterized by fibrosis and vascular abnormalities in the skin and internal organs, including the lung. SSc-associated pulmonary fibrosis (SSc-PF) is the leading cause of death in SSc patients. Pericytes are key regulators of vascular integrity and endothelial function. The role that pericytes play in SSc-PF remains unclear. We compared the transcriptome of pericytes from SSc-PF lungs (SScL) to pericytes from normal lungs (NORML). We identified 1,179 differentially expressed genes in SScL pericytes. Pathways enriched in SScL pericytes included prostaglandin, PI3K-AKT, calcium, and vascular remodeling signaling. Decreased cyclic AMP production and altered phosphorylation of AKT in response to prostaglandin E2 in SScL pericytes demonstrate the functional consequence of changes in the prostaglandin pathway that may contribute to fibrosis. The transcriptomic signature of SSc lung pericytes suggests that they promote vascular dysfunction and contribute to the loss of protection against lung inflammation and fibrosis.

Comparison of vascular endothelial growth factor expression between lesional and non-lesional skin in patients with morphea: a dermoscopy-guided immunohistochemical study

Morphea is an inflammatory fibrosing disease, initiated by vascular injury resulting in increased collagen formation and decreased collagen degradation. This study was designed to evaluate the role of angiogenic vascular endothelial growth factor (VEGF) in the vascular changes which are dermoscopically evident in morphea lesions, compared with that in non-lesional skin, by assessing its expression immunohistochemically on tissue blood vessels. Twenty patients with morphea were subjected to clinical and dermoscopic examinations. Two skin biopsies from lesional and non-lesional skin were obtained and stained with hematoxylin and eosin (H&E) and immunohistochemically with VEGF. Dermoscopic examination showed linear blood vessels in 90% of the lesions. No significant difference in the number of VEGF-stained and unstained blood vessels, was observed between the lesional and non-lesional skin (p = 0.475 and 0.191, respectively). A weak inverse correlation was found between the total number of blood vessels positive for VEGF and the disease duration, (r =  - 0.48; p = 0.032). Significant differences were found between different stages of morphea and total number of blood vessels negative for VEGF, (p = 0.017). In conclusion, VEGF immunostaining, which represents the newly formed blood vessels, showed no difference between lesional and non-lesional skin in patients with morphea. Thus, the dermoscopically observable blood vessels in lesions compared with non-lesional skin are not due to angiogenesis, but rather due to the thinning and atrophy of the overlying epidermis in morphea cases, rendering the blood vessels more obvious.

Exosomes in Systemic Sclerosis: Messengers Between Immune, Vascular and Fibrotic Components?

Systemic sclerosis (SSc) is a rare autoimmune disease, characterized by vasculopathy and fibrosis of the skin and internal organs. This disease is still considered incurable and is associated with a high risk of mortality, which is related to fibrotic events. An early diagnosis is useful for preventing complications, and targeted therapies reduce disease progression and ameliorate patients’ quality of life. Nevertheless, there are no validated biomarkers for early diagnosis with predictive prognostic value. Exosomes are membrane vesicles, transporting proteins and nucleic acids that may be delivered to target cells, which influences cellular behavior. They play important roles in cell–cell communication, both in physiological and pathological conditions, and may be useful as circulating biomarkers. Recent evidences suggest a role for these microvesicles in the three main aspects related to the pathogenesis of SSc (immunity, vascular damage, and fibrosis). Moreover, exosomes are of particular interest in the field of nano-delivery and are used as biological carriers. In this review, we report the latest information concerning SSc pathogenesis, clinical aspects of SSc, and current approaches to the treatment of SSc. Furthermore, we indicate a possible role of exosomes in SSc pathogenesis and suggest their potential use as diagnostic and prognostic biomarkers, as well as therapeutic tools.

Morphea and Eosinophilic Fasciitis: An Update

Morphea, also known as localized scleroderma, encompasses a group of idiopathic sclerotic skin diseases. The spectrum ranges from relatively mild phenotypes, which generally cause few problems besides local discomfort and visible disfigurement, to subtypes with severe complications such as joint contractures and limb length discrepancies. Eosinophilic fasciitis (EF, Shulman syndrome) is often regarded as belonging to the severe end of the morphea spectrum. The exact driving mechanisms behind morphea and EF pathogenesis remain to be elucidated. However, extensive extracellular matrix formation and autoimmune dysfunction are thought to be key pathogenic processes. Likewise, these processes are considered essential in systemic sclerosis (SSc) pathogenesis. In addition, similarities in clinical presentation between morphea and SSc have led to many theories about their relatedness. Importantly, morphea may be differentiated from SSc based on absence of sclerodactyly, Raynaud’s phenomenon, and nailfold capillary changes. The diagnosis of morphea is often based on characteristic clinical findings. Histopathological evaluation of skin biopsies and laboratory tests are not necessary in the majority of morphea cases. However, full-thickness skin biopsies, containing fascia and muscle tissue, are required for the diagnosis of EF. Monitoring of disease activity and damage, especially of subcutaneous involvement, is one of the most challenging aspects of morphea care. Therefore, data harmonization is crucial for optimizing standard care and for comparability of study results. Recently, the localized scleroderma cutaneous assessment tool (LoSCAT) has been developed and validated for morphea. The LoSCAT is currently the most widely reported outcome measure for morphea. Care providers should take disease subtype, degree of activity, depth of involvement, and quality-of-life impairments into account when initiating treatment. In most patients with circumscribed superficial subtypes, treatment with topical therapies suffices. In more widespread disease, UVA1 phototherapy or systemic treatment with methotrexate (MTX), with or without a systemic corticosteroid combination, should be initiated. Disappointingly, few alternatives for MTX have been described and additional research is still needed to optimize treatment for these debilitating conditions. In this review, we present a state-of-the-art flow chart that guides care providers in the treatment of morphea and EF.

Causes and consequences of endoplasmic reticulum stress in rheumatic disease

Rheumatic diseases represent a heterogeneous group of inflammatory conditions, many of which involve chronic activation of both innate and adaptive immune responses by multiple genetic and environmental factors. These immune responses involve the secretion of excessive amounts of cytokines and other signalling mediators by activated immune cells. The endoplasmic reticulum (ER) is the cellular organelle that directs the folding, processing and trafficking of membrane-bound and secreted proteins, including many key components of the immune response. Maintaining homeostasis in the ER is critical to cell function and survival. Consequently, elaborate mechanisms have evolved to sense and respond to ER stress through three main signalling pathways that together comprise the unfolded protein response (UPR). Activation of the UPR can rapidly resolve the accumulation of misfolded proteins, direct permanent changes in the size and function of cells during differentiation, and critically influence the immune response and inflammation. Recognition of the importance of ER stress and UPR signalling pathways in normal and dysregulated immune responses has greatly increased in the past few years. This Review discusses several settings in which ER stress contributes to the pathogenesis of rheumatic diseases and considers some of the therapeutic opportunities that these discoveries provide.

A case of localized bullous scleroderma

Bullous scleroderma is a rare type of the focal form of the disease mainly affecting the skin and characterized by induration and sclerosis foci as well as subepidermal blisters containing a transparent matter. The article describes a case study of bullous scleroderma in an adult woman with localized skin eruptions in the area of the left breast, which were completely regressed after a standard therapy with the use of drugs having an effect on collagen synthesis.

Role of microRNAs in gastrointestinal smooth muscle fibrosis and dysfunction: novel molecular perspectives on the pathophysiology and therapeutic targeting

MicroRNAs (miRNAs) belong to a group of short noncoding RNA molecules with important roles in cellular biology. miRNAs regulate gene expression by repressing translation or degrading the target mRNA. Recently, a growing body of evidence suggests that miRNAs are implicated in many diseases and could be potential biomarkers. Fibrosis and/smooth muscle (SM) dysfunction contributes to the morbidity and mortality associated with several diseases of the gastrointestinal tract (GIT). Currently available therapeutic modalities are unsuccessful in efficiently blocking or reversing fibrosis and/or SM dysfunction. Recent understanding of the role of miRNAs in signaling pathway of fibrogenesis and SM phenotype switch has provided a new insight into translational research. However, much is still unknown about the molecular targets and therapeutic potential of miRNAs in the GIT. This review discusses miRNA biology, pathophysiology of fibrosis, and aging- associated SM dysfunction in relation to the deregulation of miRNAs in the GIT. We also highlight the role of selected miRNAs associated with fibrosis and SM dysfunction-related diseases of the GIT.

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.

Clinical and laboratory features of systemic sclerosis complicated with localized scleroderma

Localized scleroderma (LSc) primarily affects skin, whereas systemic sclerosis (SSc) affects skin and various internal organs. LSc and SSc are considered to be basically different diseases, and there is no transition between them. However, LSc and SSc have several common characteristics, including endothelial cell dysfunction, immune activation, and excess fibrosis of the skin, and there exist several SSc cases complicated with LSc during the course of SSc. Clinical and laboratory characteristics of SSc patients with LSc remain unclear. We investigated the clinical and laboratory features of 8 SSc patients with LSc among 220 SSc patients (3.6%). The types of LSc included plaque (5/8), guttate (2/8), and linear type (1/8). All cases were diagnosed as having SSc within 5 years before or after the appearance of LSc. In three cases of SSc with LSc (37.5%), LSc skin lesions preceded clinical symptoms of SSc. Young age, negative antinuclear antibody, and positive anti-RNA polymerase III antibody were significantly prevalent in SSc patients with LSc. The positivity of anticentromere antibody tended to be prevalent in SSc patients without LSc. No significant difference in the frequency of complications, such as interstitial lung disease, reflux esophagitis, and pulmonary artery hypertension, was observed. The awareness of these characteristic of SSc with LSc are essential to establish an early diagnosis and treatment.

The pathogenesis of systemic sclerosis revisited

Although infectiological stimuli, environmental factors and genotypic features are known to contribute to the initiation and perpetuation of systemic sclerosis (SSc), its etiology still remains to be enigmatic, and less elusive insights are to be achieved by ongoing and future investigations. Being characterized, however, as chronic autoimmune disease with excessive collagen accumulation in skin, synovia and visceral organs such as lung, heart, and digestive tract along with obliterating angiopathy, the pathophysiology of SSc can be summarized as being based on imbalances of the cellular and humoral immune system, vascular dysfunction and activation of resident connective tissue cells. A complex interplay between these major components manages to establish and maintain the inability of the vasculature to adequately react to the need for dilatation, constriction and growth of new vessels, to cause the increased deposition of extracellular matrix constituents as well as to facilitate immunological disarrangement. Despite parallels to the chicken and egg causality dilemma, all of these account for what later clinicians observe in patients suffering from Raynaud's phenomenon, digital ulcers, sclerodactyly, rigidity of the face, microstomia, sicca syndrome, dyspnea, dry cough, pulmonary hypertension, palpitations, syncopes, renal insufficiency, dysphagia, gastroesophageal reflux, dyspepsia, generalized arthralgias, but also dyspareunia, or erectile dysfunction.

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.

Cellular and molecular aspects of vascular dysfunction in systemic sclerosis

Systemic sclerosis (SSc) is characterized by vascular alterations, activation of the immune system and tissue fibrosis. Vascular insufficiency manifests early in the disease, and although there is evidence of an active repair process, capillaries deteriorate and regress. Factors that contribute to the failure of vascular regeneration might include persistent injury, an imbalance between proangiogenic and antiangiogenic mediators, intrinsic abnormal properties of the cellular components of the vessels, and the presence of fibroblast-derived antiangiogenic factors. In addition, circulating dysfunctional endothelial progenitor cells might further exacerbate vessel deterioration. Abnormal expression of transcription factors, including Fra2 and Fli1, has been proposed to contribute to SSc vasculopathy. Fli1 regulates genes that are involved in vessel maturation and stabilization, suggesting that reduced levels of Fli1 in SSc vasculature could contribute to the development of unstable vessels that are prone to regression. Conversely, proliferating endothelial cells and pericytes, in the presence of an appropriate stimulus, might transdifferentiate into collagen-producing cells, and thus contribute to the initiation of fibrosis. Despite progress in treating the symptoms of vascular disease in SSc, the underlying mechanisms remain poorly understood. An improved knowledge of the molecular and cellular pathways that contribute to SSc vasculopathy could help in the design of effective therapies in the future.

Sonographic evaluation of pediatric localized scleroderma: preliminary disease assessment measures

BACKGROUND

Our earlier work in the ultrasonograpy of localized scleroderma (LS) suggests that altered levels of echogenicity and vascularity can be associated with disease activity. Utrasound is clinically benign and readily available, but can be limited by operator dependence. We present our efforts to standardize image acquisition and interpretation of pediatric LS to better evaluate the correlation between specific sonographic findings and disease activity.

METHODS

Several meetings have been held among our multi-center group (LOCUS) to work towards standardizing sonographic technique and image interpretation. Demonstration and experience in image acquisition were conducted at workshop meetings. Following meetings in 2007, an ultrasound measure was developed to standardize evaluation of differences in echogenicity and vascularity. Based upon our initial observations, we have labeled this an ultrasound disease activity measure. This preliminary measure was subsequently evaluated on over 180 scans of pediatric LS lesions. This review suggested that scoring levels should be expanded to better capture the range of observed differences. The revised levels and their definitions were formulated at a February 2009 workshop meeting. We have also developed assessments for scoring changes in tissue thickness and lesion size to better determine if these parameters aid evaluation of disease state.

RESULTS

We have standardized our protocol for acquiring ultrasound images of pediatric LS lesions. A wide range of sonographic differences has been seen in the dermis, hypodermis, and deep tissue layers of active lesions. Preliminary ultrasound assessments have been generated. The disease activity measure scores for altered levels of echogenicity and vascularity in the lesion, and other assessments score for differences in lesion tissue layer thickness and changes in lesion size.

CONCLUSIONS

We describe the range of sonographic differences found in pediatric LS, and present our efforts to standardize ultrasound acquisition and image interpretation for this disease. We present ultrasound measures that may aid evaluation of disease state. These assessments should be considered a work in progress, whose purpose is to facilitate further study in this area. More studies are needed to assess their validity and reliability.

Localized scleroderma and systemic sclerosis: is there a connection?

Excess fibrosis of the skin is a clinical hallmark of both localized scleroderma and systemic sclerosis. Localized scleroderma is generally thought to be a skin-limited disease whereas systemic sclerosis can have a wide range of internal organ involvement. Recent data suggest that a subset of patients with juvenile localized scleroderma can go on to develop systemic involvement of their disease. This raises the question of what the connection is, if any, between localized scleroderma and systemic sclerosis.

Fibrosis in systemic sclerosis

This article reviews current understanding of the pathophysiology of fibrosis in systemic sclerosis. It highlights recent discoveries, insights, and emerging research, and potential opportunities for the development of targeted antifibrotic therapies.

The X chromosome and systemic sclerosis

PURPOSE OF REVIEW

Similar to the majority of autoimmune rheumatic diseases, systemic sclerosis is characterized by a striking female predominance superimposed on a predisposing genetic background. At least two genetic mechanisms have been proposed that play a role in susceptibility to systemic sclerosis; firstly the maintenance of immune tolerance via genes on the X chromosomes and, secondly, fetal microchimerism. Based on these lines of evidence, experimental efforts have been most recently dedicated to investigating the role of X chromosome abnormalities (i.e. monosomy rates and inactivation patterns) in autoimmunity. We will review herein the most recent data on the role of the X chromosome in systemic sclerosis onset and discuss the potential implications.

RECENT FINDINGS

Women with systemic sclerosis manifest an enhanced rate of X monosomic cells in peripheral blood compared with healthy age-matched women. Furthermore, a severely skewed X chromosome inactivation pattern is found in women with systemic sclerosis.

SUMMARY

These observations, reproduced in other female-predominant autoimmune diseases, strongly support the role of the X chromosome in conferring susceptibility to tolerance breakdown and open novel scenarios to emphasize the unknown etiopathogenesis of systemic sclerosis. The implications of these findings will be discussed.

Intermedin: a skin peptide that is downregulated in atopic dermatitis

Intermedin (IMD), also called adrenomedullin-2, is a peptide that belongs to the calcitonin/calcitonin gene-related peptide/amylin peptide family. IMD exerts many effects on the cardiovascular system, gastrointestinal tract, and central nervous system. Here, we analyzed the expression of the IMD peptide in human skin of healthy controls, in biopsies from lesional and non-lesional areas of atopic dermatitis (AD) skin, in cultured human keratinocytes, and in the HaCaT keratinocyte cell line at the transcriptional (quantitative reverse transcription-PCR) and translational (immunohistochemistry) level. IMD messenger RNA (mRNA) and protein could be detected in keratinocytes and human skin. Keratinocytes, nerve fibers, periglandular cells, arterial/arteriolar smooth muscle cells, and pericytes of dermal microvessels were intensely IMD-immunoreactive. The IMD mRNA was, compared to healthy skin, significantly reduced in lesional and non-lesional areas of AD skin. This was accompanied by a reduction of IMD immunoreactivity in pericytes of the upper dermis indicating that skin from AD patients is generally affected, and downregulation of IMD in AD skin is not a secondary phenomenon caused by acute inflammation but is a general characteristic of AD skin. These data further point to a role of IMD expressed by pericytes in conferring higher susceptibility of the skin of AD patients to inflammatory stimuli.

Pericytes from human non-small cell lung carcinomas: An attractive target for anti-angiogenic therapy

Anti-angiogenic strategies have largely focused on endothelial cells and progenitors. However, pericytes are also an important component of vasculature. Perivascular cells from normal tissues have been widely reported, yet have not been extensively studied from human tumors. We have investigated pericytes from tumors of patients with lung cancer, the leader of cancer-related deaths in both men and women. Antibodies and magnetic beads were used to isolate cells from non-small cell lung carcinomas (NSCLC). The morphology of the pericytes was distinct with multiple elongated cytoplasmic extensions. Molecular expression of angiogenic genes was quantified by RT-PCR. Flow cytometric analysis shows that NSCLC pericytes express antigens such NG2 and VEGFR1 and present the ganglioside 3G5. The value of pericytes as models of tumor vasculature was demonstrated in cell-culture-based angiogenesis assays such as tube formation and proliferation. Results show that pericytes from some NSCLC but not all were able to maintain tubes networks on Matrigel. Pericyte function can be influenced by angiogenic growth factors or anti-angiogenic agents. Pericytes displayed invasive action against NSCLC clusters in the absence of other cell types. Perivascular cells contribute to the progression of disease and are an attractive target for anti-angiogenic therapy.

The differential expression of VEGF, VEGFR-2, and GLUT-1 proteins in disease subtypes of systemic sclerosis

Our aim was to evaluate (a) whether there is differential expression of the endothelial regulator vascular endothelial growth factor (VEGF), its receptor (VEGFR-2), and the hypoxia-associated glucose transporter molecule, GLUT-1, in skin biopsies from different disease subtypes of systemic sclerosis (SSc) and (b) whether they associate with dermal calcinosis, a significant complication of SSc. Skin punch biopsies were taken from the forearms of 66 SSc patients including 18 with limited cutaneous disease without calcinosis (lcSSc), 23 with calcinosis (lcSSc/cal), and 25 with diffuse cutaneous disease (dcSSc) and from 12 healthy control subjects. The histological appearance of the skin was graded as G0 (normal), G1 (dermal edema), or G2 or G3 (increasing fibrotic changes). Immunohistochemistry was performed with antibodies to VEGF, VEGFR-2, and GLUT-1. Staining was assessed in the epidermis, microvessels, and fibroblasts. The Kruskal-Wallis 1-way analysis of variance was used to compare the data between disease groups. VEGF protein was located in the epidermis and in dermal endothelial cells, pericytes, fibroblasts, and inflammatory cells. In dcSSc only, there was a significant increase in VEGF staining intensity in the keratinocytes and pericytes and the lowest percentage of microvessels with VEGF-positive endothelial cells. GLUT-1 protein was located in the epidermis, erythrocytes, and perineurium. In both lcSSc/cal and dcSSC, but not lcSSc, there were significant increases in GLUT-1 staining intensity of keratinocytes. We propose that in patients with dcSSc, there is a net increase in unbound VEGF in skin that may account for the raised levels of VEGF in serum reported by others. Increased GLUT-1 expression in lcSSc/cal and dcSSc indicates that hypoxia is an associated factor.

Alterations of Basement Membrane Zone and Cutaneous Microvasculature in Morphea and Extragenital Lichen Sclerosus

The aim of this study was to compare alterations of the basement membrane zone (BMZ) and to visualize changes within the skin vascular network in morphea and extragenital lichen sclerosus with the use of laser scanning confocal microscopy. This work was performed in eight plaques of morphea (three active and five inactive) and eight of lichen sclerosus (three of short duration and five long-lasting). Biopsy specimens from six healthy individuals served as controls. The biopsies were cut into 40-microm-thick sections, labeled with antibodies against beta4-intergin (a lamina lucida marker), collagen IV, and the N-terminal end of collagen VII (lamina densa markers) and C-terminal end of collagen VII (a sublamina densa marker) and studied using laser scanning confocal microscopy. Three-dimensional reconstruction of various regions of the BMZ showed a decreased number and size of the dermal papillae both in morphea and lichen sclerosus compared with normal skin. In morphea, the continuity of the BMZ at the level of lamina lucida, lamina densa, and sublamina densa was preserved whereas in LS numerous invaginations and holes were present in the BMZ at the level of the lamina lucida and lamina densa. Thus the alterations of the BMZ in morphea differ from those in lichen sclerosus. Three-dimensional reconstruction of the skin vascular network showed increased angiogenesis only in the early inflammatory stage of morphea, whereas in inactive morphea and lichen sclerosus various numbers of enlarged vessels were visible. The changes in the vascular network in morphea appear to be related to the activity of the disease.

Shared expression of phenotypic markers in systemic sclerosis indicates a convergence of pericytes and fibroblasts to a myofibroblast lineage in fibrosis

The mechanisms by which microvascular damage leads to dermal fibrosis in diffuse cutaneous systemic sclerosis (dcSSc) are unclear. We hypothesized that microvascular pericytes constitute a cellular link between microvascular damage and fibrosis by transdifferentiating into myofibroblasts. We used a combination of immunohistochemistry and double immunofluorescence labelling of frozen skin biopsies taken from normal and dcSSc patients to determine whether a phenotypic link between pericytes and myofibroblasts exists in dcSSc. Using α-smooth muscle actin, the ED-A splice variant of fibronectin (ED-A FN) and Thy-1 to identify myofibroblasts, we demonstrated the presence of myofibroblasts in fibrotic dcSSc skin. Myofibroblasts were totally absent from control skin, atrophic stage dcSSc skin and non-lesional skin. Using double immunofluorescence labelling, both myofibroblasts and pericytes were shown to express ED-A FN and Thy-1 in dcSSc skin but not in control skin. Proliferating cell nuclear antigen was also expressed by myofibroblasts and pericytes in dcSSc skin while being absent in control skin. These observations suggest that the presence of myofibroblasts may represent a transitional phase during the fibrotic stages of dcSSc and that Thy-1^+ve pericytes participate in the fibrogenic development of dcSSc by synthesizing ED-A FN, which may be associated with a proliferation and transition of pericytes and fibroblasts to myofibroblasts, thus linking microvascular damage and fibrosis.