Pathophysiology of systemic sclerosis: current understanding and new insights

Prevalence and predictors of small intestinal bacterial overgrowth in systemic sclerosis: a systematic review and meta-analysis

The reported prevalence of small intestinal bacterial overgrowth (SIBO) among patients with systemic sclerosis (SSc) is highly variable. We conducted this systematic review and meta-analysis to estimate the prevalence and identify predictors of SIBO in SSc by summarizing all of the available data. A comprehensive literature search of the PubMed, Cochrane Library, and EMBASE databases from inception to July 2020 was conducted for studies correlating SIBO with SSc. Studies were screened, and relevant data were extracted and analyzed. The pooled prevalence of SIBO among SSc patients and the odds ratio (OR) of SIBO among SSc patients compared with healthy controls were calculated. Furthermore, predictors of SIBO in SSc were evaluated. Fourteen studies containing 700 SSc patients and 217 healthy controls met the inclusion criteria. The pooled prevalence of SIBO in SSc was 34% (95% CI 27-42%). The OR of SIBO in SSc patients was 12.51 (95% CI 6.51-24.03) compared with the healthy controls. Subgroup analyses showed that the prevalence of SIBO in SSc was higher in studies using the lactulose hydrogen breath test (LHBT) for diagnosis (56%, 95% CI 46-67%) compared with those that used the glucose hydrogen breath test (GHBT) (27%, 95%CI 20-35%) and a jejunal aspirated culture (JAC) (35%, 95%CI 25-51%). The prevalence of SIBO in SSc was higher in studies conducted in Western countries (38%, 95% CI 31-47%) than those conducted in Asian countries (15%, 95%CI 10-23%), and the prevalence of SIBO in the SSc population defined by ACR-EULAR 2013 (50%, 95% CI 0.21-0.79) was higher than the prevalence defined by ACR 1980 (30%, 95% CI 0.17-0.42) or other criteria (32%, 95% CI 0.16-0.48) Moreover, the risk of diarrhea was higher in SSc patients with SIBO than those without SIBO (OR 8.82, 95% CI 4.09-19, P < 0.00001); gender, SSc subset, digital ulcer, and pulmonary fibrosis do not seem to be associated with SIBO in SSc. Antibiotic therapy seems to be effective with SIBO in SSc patients. Approximately one-third of SSc patients tested positive for SIBO with a significantly increased risk over the controls. The prevalence of SIBO in SSc varied according to the SIBO diagnostic test performed, geographic area, and SSc diagnostic criteria. The presence of diarrhea may be a predictor of SIBO in SSc. Antibiotic treatment can lead to eradication of SIBO and gastrointestinal symptomatic improvement in SSc patients. Key Points • The pooled prevalence of SIBO in SSc patients was 34%, which varied according to the SIBO diagnostic test performed, geographic area and SSc diagnostic criteria. • The risk of SIBO in SSc was increased by nearly thirteenfold compared to the healthy controls. • Diarrhoea, but not gender, SSc subset, digital ulcer and pulmonary fibrosis, was associated with SIBO in SSc patients. • For SSc patients with SIBO, antibiotic treatment can lead to eradication of SIBO and gastrointestinal symptomatic improvement.

Nailfold capillaroscopy : a comprehensive review on common findings and clinical usefulness in non-rheumatic disease

Nailfold video-capillaroscopy (NVC) is a useful diagnostic tool, used to early detect abnormalities in micro-circulation, providing a qualitative description of microvascular anomalies in Raynaud's phenomenon. NVC role in the diagnosis of Systemic Sclerosis is well known. In other rheumatic conditions such as connective tissue diseases, vasculitis, and arthritis, the NVC anomalies are often included in a scleroderma like pattern. The use of NVC in non-rheumatic diseases (NRD), with remarkable microvascular damage, as diabetes, is not standardized yet, although several research studies are carrying on. The aim of this article is to provide a resume of published results in order to lay the groundwork for the employment of NVC both in the diagnosis and follow up of microvascular complication in NRD. Furthermore, we mention NVC findings in pathologies without well recognize microvascular damages in their pathogenesis : micro-vessels abnormalities may suggest a different point of view. J. Med. Invest. 68 : 6-14, February, 2021.

CD146/sCD146 in the Pathogenesis and Monitoring of Angiogenic and Inflammatory Diseases

CD146 is a cell adhesion molecule expressed on endothelial cells, as well as on other cells such as mesenchymal stem cells and Th17 lymphocytes. This protein also exists in a soluble form, whereby it can be detected in biological fluids, including the serum or the cerebrospinal fluid (CSF). Some studies have highlighted the significance of CD146 and its soluble form in angiogenesis and inflammation, having been shown to contribute to the pathogenesis of many inflammatory autoimmune diseases, such as systemic sclerosis, mellitus diabetes, rheumatoid arthritis, inflammatory bowel diseases, and multiple sclerosis. In this review, we will focus on how CD146 and sCD146 contribute to the pathogenesis of the aforementioned autoimmune diseases and discuss the relevance of considering it as a biomarker in these pathologies.

Osteitis in Systemic Sclerosis: a nationwide case-control retrospective study (SCLEROS Study)

OBJECTIVE

Systemic sclerosis (SSc) is an autoimmune (AI) connective tissue disorder characterized by skin fibrosis, vasculopathy and dysimmunity. Data regarding osteitis in SSc are scarce.

METHOD

We performed a nationwide multicentre retrospective case-control study including patients with SSc according to the 2013 ACR/EULAR classification, with a diagnosis of osteitis. The objectives of the study were to describe, to characterize, and to identify associated factors for osteitis in patients with SSc.

RESULTS

Forty-eight patients were included. Twenty-six patients (54.1%) had osteitis beneath digital tip ulcers. Physical symptoms included: pain (36/48, 75%), erythema (35/48, 73%), and local warmth (35/48, 73%). Thirty-one (65%) patients had C-reactive protein levels >2 mg/L (8 [2.7 - 44.3] mg/L). On X-ray, CT-scans or MRI, osteitis was characterized by swelling or abscess of soft tissues with acro-osteolysis or lysis in 28 patients (58%). Microbiological sampling was performed in 45 (94%) patients. Most pathogens were Staphylococcus aureus (43.8%); anaerobes and Enterobacteriaceae (29.1%) and Pseudomonas aeruginosa (10.4%). Management comprised antibiotics in 37 (77.1%) patients and/or surgery in 26 (54.2%). Fluoroquinolones were used in 22 (45.8%) patients and amoxicillin + beta-lactamase inhibitor in 7 (14.6%). Six (12.6%) patients relapsed, 6 (12.6%) patients had osteitis recurrence, 15 (32%) sequelae, and 2 patients had septic shock and died.

CONCLUSION

This study confirmed digital tip ulcers as an associated factor for osteitis, and revealed a high rate of functional sequelae. Antimicrobial therapy with oral fluoroquinolone or intravenous amoxicillin and beta-lactamase inhibitor are used as first-line antibiotherapy in SSc patients with osteitis.

Apremilast interferes with the TGFβ1-induced transition of human skin fibroblasts into profibrotic myofibroblasts: in vitro study

OBJECTIVES

Fibroblast-to-myofibroblast transition and extracellular matrix overproduction represent progressive events in chronic inflammatory and fibrotic diseases, in which TGFβ1 is one of the key mediators. Phosphodiesterase 4 (PDE4) acts as a proinflammatory enzyme through the degradation of cyclic adenosine monophosphate and it is overexpressed in skin fibroblasts. The study investigated how apremilast (a PDE4 inhibitor) interferes with the intracellular signalling pathways responsible for the TGFβ1-induced fibroblast-to-myofibroblast transition and profibrotic extracellular matrix protein synthesis.

METHODS

Cultured human skin fibroblasts were stimulated with TGFβ1 (10 ng/ml) alone or combined with apremilast (1 and 10 μM) for 4, 16 and 24 h. Other aliquots of the same cells were previously stimulated with TGFβ1 and then treated with apremilast (1 and 10 μM) for 4, 16 and 24 h, always under stimulation with TGFβ1. Gene and protein expression of αSMA, type I collagen (COL1) and fibronectin were evaluated, together with the activation of small mothers against decapentaplegic 2 and 3 (Smad2/3) and extracellular signal-regulated kinase (Erk1/2) proteins.

RESULTS

Apremilast reduced the TGFβ1-induced increase in αSMA, COL1 and fibronectin gene expression at 4 and 16 h, and protein synthesis at 24 h of treatment in cultured fibroblasts, even for cells already differentiated into myofibroblasts by way of a previous stimulation with TGFβ1. Apremilast inhibited the TGFβ1-induced Smad2/3 and Erk1/2 phosphorylation at 15 and 30 min.

CONCLUSION

Apremilast seems to inhibit in vitro the fibroblast-to-myofibroblast transition and the profibrotic activity induced by TGFβ1 in cultured human skin fibroblasts by downregulating Smad2/3 and Erk1/2 intracellular signalling pathways.

Coexistence of systemic and localized scleroderma: a systematic literature review and observational cohort study

OBJECTIVE

SSc and localized sclerosis (LoS) are considered clinically distinct entities. We describe herein the coexistence of SSc and LoS by both a systematic literature review and an observational cohort study of unselected SSc patients.

METHODS

Original studies documenting the coexistence of SSc and LoS were identified in three electronic databases by means of a systematic literature search according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Additionally, the coexistence of SSc and LoS was studied in a prospective cohort of SSc patients visiting the Ghent University Scleroderma Unit for their yearly follow-up visit between January 2018 and January 2019.

RESULTS

Five studies were finally included for quality appraisal and data extraction. The coexistence of SSc and LoS ranged between 2.4 and 7.4%. RP, scleroderma pattern on nailfold videocapillaroscopy (NVC) and the presence of SSc-specific antibodies were commonly observed in coexistent cases. Additionally, coexistence of SSc and LoS was found in 8/296 (2.7%) consecutive SSc patients of the Ghent University Scleroderma Unit. RP was present in 6/8 coexistent cases; a scleroderma pattern on NVC was observed in all coexistent cases, and SSc-specific antibodies (i.e. cenp-B) were found in 4/8 coexistent cases.

CONCLUSION

This is the first systematic literature review with additional cohort evaluation investigating the coexistence of SSc and LoS. A relatively high overlap of SSc and LoS was revealed, which is peculiar because both are rare diseases.

The effect of trauma care systems on the mortality of injured adult patients: A protocol for systematic review and meta-analysis

PURPOSE

The aim of this study was to have a comprehensive evaluation of the effect of trauma care systems on the mortality of injured adult patients.

MATERIALS AND METHODS

This protocol established in this study has been reported following the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols. Web of Science, PubMed, EMBASE, Scopus, and the Cochrane Library were searched for all clinical trials evaluating the effect of trauma care systems on the mortality of injured adult patients until July 31, 2020. We will use a combination of Medical Subject Heading and free-text terms with various synonyms to search based on the eligibility criteria. Two investigators independently reviewed the included studies and extracted relevant data. The odds ratio (OR) and 95% confidence intervals (CIs) were used as effect estimate. I-square (I) test, substantial heterogeneity, sensitivity analysis, and publication bias assessment will be performed accordingly. Stata 15.0 and Review Manger 5.3 are used for meta-analysis and systematic review.

RESULTS

The results will be published in a peer-reviewed journal.

CONCLUSION

The results of this review will be widely disseminated through peer-reviewed publications and conference presentations. This evidence may also provide a comprehensive evaluation of the effect of trauma care systems on the mortality of injured adult patients.

REGISTRATION NUMBER

INPLASY202080058.

Pericarditis in Systemic Rheumatologic Diseases

PURPOSE OF REVIEW

We review the epidemiology, pathophysiology, and management of pericarditis most commonly complicating autoimmune and autoinflammatory conditions.

RECENT FINDINGS

Typically, pericarditis occurs in the context of a systemic flare of the underlying disease but infrequently, it is the presenting manifestation requiring a high index of suspicion to unravel the indolent cause. Pericardial involvement in rheumatic diseases encompasses a clinical spectrum to include acute, recurrent and incessant pericarditis, constrictive pericarditis, asymptomatic pericardial effusion, and pericardial tamponade. Direct evidence on the pathophysiology of pericarditis in the context of rheumatic diseases is scant. It is theorized that immune perturbations within pericardial tissue result from the underlying central immunopathology of the respective autoimmune or autoinflammatory disease. Pericarditis management depends on acuity, the underlying cause and epidemiological features such as patient's immune status and geographic prevalence of infections such as tuberculosis. Immunosuppressive medications including biologics such as interleukin 1 blockers emerge as possible steroid sparing agents for pericarditis treatment.

Anti-CXCL4 Antibody Reactivity Is Present in Systemic Sclerosis (SSc) and Correlates with the SSc Type I Interferon Signature

Systemic sclerosis (SSc) is characterized by skin/internal organ fibrosis, vasculopathy and autoimmunity. Chemokine (C-X-C motif) ligand 4 (CXCL4) is an SSc biomarker, predicting unfavorable prognosis and lung fibrosis. CXCL4 binds DNA/RNA and favors interferon (IFN)-α production by plasmacytoid dendritic cells (pDCs), contributing to the type I IFN (IFN-I) signature in SSc patients. However, whether CXCL4 is an autoantigen in SSc is unknown. Here, we show that at least half of SSc patients show consistent antibody reactivity to CXCL4. T-cell proliferation to CXCL4, tested in a limited number of patients, correlates with anti-CXCL4 antibody reactivity. Antibodies to CXCL4 mostly correlate with circulating IFN-α levels and are significantly higher in patients with lung fibrosis in two independent SSc cohorts. Antibodies to CXCL4 implement the CXCL4-DNA complex's effect on IFN-α production by pDCs; CXCL4-DNA/RNA complexes stimulate purified human B-cells to become antibody-secreting plasma cells in vitro. These data indicate that CXCL4 is indeed an autoantigen in SSc and suggest that CXCL4, and CXCL4-specific autoantibodies, can fuel a harmful loop: CXCL4-DNA/RNA complexes induce IFN-α in pDCs and direct B-cell stimulation, including the secretion of anti-CXCL4 antibodies. Anti-CXCL4 antibodies may further increase pDC stimulation and IFN-α release in vivo, creating a vicious cycle which sustains the SSc IFN-I signature and general inflammation.

The importance of skin manifestations, serology and nailfold (video)capillaroscopy in morphea and systemic sclerosis: current understanding and new insights

Since the field around morphea and systemic sclerosis (SSc) is evolving rapidly, this review approaches conventional as well as more recent clinical developments from a dermatological point of view. Skin manifestations are critical in sub-classifying these diseases ensuring a correct prognosis for these patients. They can be discretely present, and therefore, diagnosis can be challenging sometimes, implicating a thorough dermatological examination is mandatory. Furthermore, a growing amount of dermatologists perform nailfold videocapillaroscopy (NVC), a more recent reliable non-invasive imaging technique used for in vivo assessment of the microcirculation at the nailfold. After all, specific NVC-changes are present in a majority of patients with SSc. This way, dermatologists not only take part in the diagnosis process through clinical investigation but also through the use of a modern state of the art imaging technique that is becoming the golden standard in SSc multidisciplinary workup. In this review, current understandings for NVC in morphea and SSc are revised. So far, the role of NVC in the diagnosis/prognosis/classification of morphea patients has not been thoroughly investigated to make proper conclusions. As for SSc, it is well known that NVC contributes to the diagnosis and can make a fundamental difference especially when obvious clinical SSc signs are absent. This review emphasizes the (somewhat underestimated) role of dermatologists in the process of diagnosis and follow-up, and thus, the difference we can make for our patients and fellow colleagues in the multidisciplinary workup of SSc and morphea.

The Role of Endogenous Eicosapentaenoic Acid and Docosahexaenoic Acid-Derived Resolvins in Systemic Sclerosis

Resolvins, the member of specialized pro-resolving mediators, are produced from omega-3 polyunsaturated fatty acids as a response to an acute inflammatory process in that termination and resolution of inflammation. In the acute inflammation, these lipid mediators limit polymorphonuclear cells infiltration, proinflammatory cytokine production; promote efferocytosis, and regulate several cell types being important roles in innate and adaptive immunity. Any dysregulation or defect of the resolution phase result in prolonged, persistent inflammation and eventually fibrosis. Resolvins are implicated in the development of various chronic autoimmune diseases. Systemic sclerosis (SSc) is a very complicated, chronic autoimmune disorder proceeding with vasculopathy, inflammation, and fibrosis. Dysregulation of innate and adaptive immunity is another important contributing factor in the pathogenesis of SSc. In this review, we will focus on the different roles of this new family of lipid mediators, characterized by the ability to prevent the spread of inflammation and its chronicity in various ways and how they can control the development of fibrotic diseases like SSc.

Increased expression of the transforming growth factor β–inducible gene HIC-5 in systemic sclerosis skin and fibroblasts: a novel antifibrotic therapeutic target

Objective

SSc is a systemic fibrotic disease affecting skin, numerous internal organs and the microvasculature. The molecular pathogenesis of SSc tissue fibrosis has not been fully elucidated, although TGF-β1 plays a crucial role. The Hic-5 protein encoded by the TGF-β1-inducible HIC-5 gene participates in numerous TGF-β-mediated pathways, however, the role of Hic-5 in SSc fibrosis has not been investigated. The aim of this study was to examine HIC-5 involvement in SSc tissue fibrosis.

Methods

Affected skin from three patients with diffuse SSc and dermal fibroblasts cultured from affected and non-affected SSc skin were examined for HIC-5 and COL1A1 gene expression. Real-time PCR, IF microscopy, western blotting and small interfering RNA–mediated HIC-5 were performed.

Results

HIC-5 and COL1A1 transcripts and Hic-5, type 1 collagen (COL1) and α-smooth muscle actin (α-SMA) protein levels were increased in clinically affected SSc skin compared with normal skin and in cultured dermal fibroblasts from affected SSc skin compared with non-affected skin fibroblasts from the same patients. HIC-5 knockdown caused a marked reduction of COL1 production in SSc dermal fibroblasts.

Conclusion

HIC-5 expression is increased in affected SSc skin compared with skin from normal individuals. Affected SSc skin fibroblasts display increased HIC-5 and COL1A1 expression compared with non-affected skin fibroblasts from the same patients. Hic-5 protein was significantly increased in cultured SSc dermal fibroblasts. HIC-5 mRNA knockdown in SSc fibroblasts caused &gt;50% reduction of COL1 production. Although these are preliminary results owing to the small number of skin samples studied, they indicate that Hic-5 plays a role in the profibrotic activation of SSc dermal fibroblasts and may represent a novel molecular target for antifibrotic therapy in SSc.

Toll-like receptors in mediating pathogenesis in systemic sclerosis

Toll-like receptors (TLRs) are evolutionarily conserved receptors essential for the host defence against pathogens. Both immune and non-immune cells can express TLRs, although at different levels. Systemic sclerosis (SSc) is a chronic disease in which autoimmunity, dysregulated profibrotic mediator release and activation of fibroblasts lead to dysregulated collagen deposition and fibrosis. There is now increasing knowledge that the innate immune system and, in particular, TLRs take a part in SSc pathogenesis. The list of endogenous ligands that can stimulate TLRs in SSc is growing: these ligands represent specific danger-associated molecular patterns (DAMPs), involved either in the initiation or the perpetuation of inflammation, and in the release of factors that sustain the fibrotic process or directly stimulate the cells that produce collagen and the endothelial cells. This review reports evidences concerning TLR signalling involvement in SSc. We report the new DAMPs, as well as the TLR-linked pathways involved in disease, with emphasis on type I interferon signature in SSc, the role of plasmacytoid dendritic cells (pDCs) and platelets. The dissection of the contribution of all these pathways to disease, and their correlation with the disease status, as well as their values as prognostic tools, can help to plan timely intervention and design new drugs for more appropriate therapeutic strategies.

Contribution of Sex and Autoantibodies to Microangiopathy Assessed by Nailfold Videocapillaroscopy in Systemic Sclerosis: A Systematic Review of the Literature

Objective

Microangiopathy and dysregulation of the immune system play important roles in the pathogenesis of systemic sclerosis (SSc). Factors that trigger vascular injury in SSc have not been elucidated so far. We undertook this study to evaluate whether sex or expression of specific antinuclear autoantibodies might associate with the degree of microangiopathy through performance of a systematic review that summarizes what is known about these associations.

Methods

A standardized search of PubMed, Embase, Web of Science, and the Cochrane Library were performed to identify studies that described autoantibodies in SSc patients and microangiopathy and, for the second search, those that described sex and microangiopathy.

Results

We included 11 studies that described the relationship between SSc‐specific autoantibodies and microangiopathy and 6 studies that reported on the association between sex and microangiopathy. Contradictory results were found on the association between SSc‐specific autoantibodies and microangiopathy, and no association was found between sex and microangiopathy based on the current literature.

Conclusion

Based on this review of the literature, we can conclude that sex does not seem to influence degree of microangiopathy in SSc, while results on association between SSc‐specific autoantibodies and degree of microangiopathy were inconclusive.

Analysis of gene expression profiles and protein-protein interaction networks in multiple tissues of systemic sclerosis

Background

Systemic sclerosis (SSc), a multi-organ disorder, is characterized by vascular abnormalities, dysregulation of the immune system, and fibrosis. The mechanisms underlying tissue pathology in SSc have not been entirely understood. This study intended to investigate the common and tissue-specific pathways involved in different tissues of SSc patients.

Methods

An integrative gene expression analysis of ten independent microarray datasets of three tissues was conducted to identify differentially expressed genes (DEGs). DEGs were mapped to the search tool for retrieval of interacting genes (STRING) to acquire protein–protein interaction (PPI) networks. Then, functional clusters in PPI networks were determined. Enrichr, a gene list enrichment analysis tool, was utilized for the functional enrichment of clusters.

Results

A total of 12, 2, and 4 functional clusters from 619, 52, and 119 DEGs were determined in the lung, peripheral blood mononuclear cell (PBMC), and skin tissues, respectively. Analysis revealed that the tumor necrosis factor (TNF) signaling pathway was enriched significantly in the three investigated tissues as a common pathway. In addition, clusters associated with inflammation and immunity were common in the three investigated tissues. However, clusters related to the fibrosis process were common in lung and skin tissues.

Conclusions

Analysis indicated that there were common pathological clusters that contributed to the pathogenesis of SSc in different tissues. Moreover, it seems that the common pathways in distinct tissues stem from a diverse set of genes.

Associations of Vitamin D Receptor Single Nucleotide Polymorphisms with Susceptibility to Systemic Sclerosis

BACKGROUND

This study aims to evaluate whether the Vitamin D receptor (VDR) gene polymorphisms were associated with systemic sclerosis (SSc) in a Chinese Han population.

METHODS

Using a hospital-based case-control study including 100 SSc patients and 100 healthy controls. Single nucleotide polymorphisms (SNPs) in the VDR region were genotyped by the improved multiplex ligase detection reaction (i MLDR) method. Haplotypes were also constructed after linkage disequilibrium (LD) analysis.

RESULTS

Eight SNPs (rs731236 (TaqI), rs2228570 (FokI), rs7975232 (ApaI), rs1544410 (BsmI), rs11574010 (Cdx2), rs739837 (BglI), rs757343 (Tru9I) and rs11168267) were included. There were significant differences between SSc patients and healthy individuals in ApaI and BglI genotype (both adjusted p = 0.008). Through the genotyping, significantly association of SSc were found for: dominant model of ApaI and BglI (both OR (95% CI) = 1.80 (1.03,3.16), p = 0.040). Furthermore, the elevation of erythrocyte sedimentation rate (ESR) had a higher percentage of BglI GT genotype frequency (p = 0.034) and dominant model of ApaI (p = 0.016) in SSc. There was high linkage disequilibrium was detected in BglI and ApaI polymorphisms (r² = 1.0, D' = 1.0), Tru9I and rs11168267 (r² = 0.926, D' = 0.969), respectively. No significant difference were found in these four haplotypes (all p >0.05). The correlation between VD levels and VDR gene polymorphisms was not statistically significant.

CONCLUSIONS

Our preliminary study indicates the ApaI and BglI genotype may possibly have a role in the pathogenesis of SSc patients. Dominant model of ApaI and BglI GT genotype frequency may be associated with the increased risk of ESR.