Systemic sclerosis mortality in the United States: 1979-1998

Distinct genome-wide DNA methylation and gene expression signatures in classical monocytes from African American patients with systemic sclerosis

BACKGROUND

Systemic sclerosis (SSc) is a multisystem autoimmune disorder that has an unclear etiology and disproportionately affects women and African Americans. Despite this, African Americans are dramatically underrepresented in SSc research. Additionally, monocytes show heightened activation in SSc and in African Americans relative to European Americans. In this study, we sought to investigate DNA methylation and gene expression patterns in classical monocytes in a health disparity population.

METHODS

Classical monocytes (CD14+ + CD16-) were FACS-isolated from 34 self-reported African American women. Samples from 12 SSc patients and 12 healthy controls were hybridized on MethylationEPIC BeadChip array, while RNA-seq was performed on 16 SSc patients and 18 healthy controls. Analyses were computed to identify differentially methylated CpGs (DMCs), differentially expressed genes (DEGs), and CpGs associated with changes in gene expression (eQTM analysis).

RESULTS

We observed modest DNA methylation and gene expression differences between cases and controls. The genes harboring the top DMCs, the top DEGs, as well as the top eQTM loci were enriched for metabolic processes. Genes involved in immune processes and pathways showed a weak upregulation in the transcriptomic analysis. While many genes were newly identified, several other have been previously reported as differentially methylated or expressed in different blood cells from patients with SSc, supporting for their potential dysregulation in SSc.

CONCLUSIONS

While contrasting with results found in other blood cell types in largely European-descent groups, the results of this study support that variation in DNA methylation and gene expression exists among different cell types and individuals of different genetic, clinical, social, and environmental backgrounds. This finding supports the importance of including diverse, well-characterized patients to understand the different roles of DNA methylation and gene expression variability in the dysregulation of classical monocytes in diverse populations, which might help explaining the health disparities.

Worsening premature death burden gap from systemic sclerosis in men and black persons: A US nationwide population-based study

Objective

Male sex and black race incur poor prognosis in systemic sclerosis (SSc). There is no nationwide population-based assessment of premature SSc death burden by sex and race.

Methods

This is a population-based study comprising all recorded SSc deaths across the United States. We constructed histograms depicting the number of SSc deaths for each age by sex and race, and calculated the cumulative percent death at each age and the median age of death. We determined the odds ratios for the risk of premature death from SSc by sex and race. We then calculated the percent of total SSc deaths for different age groups by sex and race from 1970 to 2015. We performed chi-square test with Yates's correction and quantified the odds ratio (OR) with 95% confidence interval (CI).

Results

The median age of SSc death was 63 years in males versus 68 years in females, and 57 years in blacks versus 70 years in whites. The odds for SSc death before 65 years age was 1.8 (95% CI, 1.6-2.0) for males compared with females and 5.1 (95% CI, 4.4-6.0) for blacks compared with whites. The higher odds for premature death in males than in females was similar for both races. Differences in the proportions of premature deaths from 1970 to 2015 increased between males and females (-5% to 17%) and between blacks and whites (14% to 36%).

Conclusion

Males and black persons die of SSc at younger ages. The worsening premature death burden gap between the two sexes and races over the last five decades is troublesome.

Trends in Systemic Sclerosis Mortality Over Forty-Eight Years, 1968-2015: A US Population-Based Study

OBJECTIVE

To identify secular trends associated with systemic sclerosis (SSc) mortality over a 48-year period.

METHODS

Using national mortality data compiled by the Centers for Disease Control and Prevention's Wide-Ranging Online Data for Epidemiologic Research, and population data from the US Census Bureau, we calculated an age-standardized mortality rate (ASMR) for SSc and non-SSc (all other causes), and we also calculated the ratio of the SSc ASMR to the non-SSc ASMR for each year from 1968 to 2015. We then used a joinpoint regression model to evaluate mortality trends overall and by sex and race.

RESULTS

From 1968 to 2015, there were 46,798 deaths with SSc recorded as the "underlying" cause of death and 106,058,839 non-SSc deaths. There were an additional 9,063 deaths with SSc recorded as a "contributing" cause of death from 1999 to 2015. Whereas the non-SSc ASMR decreased throughout the 48-year time period, the SSc ASMR increased from 1968 to 2000, followed by decreases each year from 2001 to 2015. The SSc ASMR also decreased for deaths where SSc was a contributing cause from 1999 to 2015. Women and Black persons had higher SSc ASMRs and SSc ASMR to non-SSc ASMR ratios than men and White persons, respectively. Additionally, SSc ASMRs and SSc ASMR to non-SSc ASMR ratios increased at higher rates in women and White persons than in men and Black persons, respectively, during the initial three decades.

CONCLUSION

Mortality attributable to SSc increased from 1968 to 2000, followed by a steady decline from 2001 to 2015. However, SSc mortality relative to non-SSc mortality remains high. SSc mortality has disproportionately changed by sex and race over the 48-year period assessed in the present study.

Differential DNA Methylation Landscape in Skin Fibroblasts from African Americans with Systemic Sclerosis

The etiology and reasons underlying the ethnic disparities in systemic sclerosis (SSc) remain unknown. African Americans are disproportionally affected by SSc and yet are underrepresented in research. The aim of this study was to comprehensively investigate the association of DNA methylation levels with SSc in dermal fibroblasts from patients of African ancestry. Reduced representation bisulfite sequencing (RRBS) was performed on primary dermal fibroblasts from 15 SSc patients and 15 controls of African ancestry, and over 3.8 million CpG sites were tested for differential methylation patterns between cases and controls. The dermal fibroblasts from African American patients exhibited widespread reduced DNA methylation. Differentially methylated CpG sites were most enriched in introns and intergenic regions while depleted in 5' UTR, promoters, and CpG islands. Seventeen genes and eleven promoters showed significant differential methylation, mostly in non-coding RNA genes and pseudogenes. Gene set enrichment analysis (GSEA) and gene ontology (GO) analyses revealed an enrichment of pathways related to interferon signaling and mesenchymal differentiation. The hypomethylation of DLX5 and TMEM140 was accompanied by these genes' overexpression in patients but underexpression for lncRNA MGC12916. These data show that differential methylation occurs in dermal fibroblasts from African American patients with SSc and identifies novel coding and non-coding genes.

The Contribution of Genetics and Epigenetics to Our Understanding of Health Disparities in Rheumatic Diseases

Socioeconomic determinants of health are associated with worse outcomes in the rheumatic diseases and contribute significantly to health disparities. However, genetic and epigenetic risk factors may affect different populations disproportionally and further exacerbate health disparities. We discuss the role of genetics and epigenetics to the health disparities observed in rheumatic diseases. We review concepts of population genetics and natural selection, current genome-wide genetic and epigenetic studies of several autoimmune diseases, and environmental exposures associated with disease risk in different populations. To understand how genomics influence health disparities in the rheumatic diseases, further studies in different populations worldwide are needed.

Exome-Wide Association Analysis Suggests LRP2BP as a Susceptibility Gene for Endothelial Injury in Systemic Sclerosis in the Han Chinese Population

Genetic factors play a key role in the pathogenesis of autoimmune diseases, whereas the disease-causing variants remain largely unknown. Herein, we performed an exome-wide association study of systemic sclerosis in a Han Chinese population. In the discovery stage, 527 patients with systemic sclerosis and 5,024 controls were recruited and genotyped. In the validation study, an independent sample set of 479 patients and 1,096 controls were examined. In total, we found that four independent signals reached genome-wide significance. Among them, rs7574865 (P_combined = 3.87 × 10^-12) located within signal transducer and activator of transcription 4 gene was identified previously using samples of European ancestry. Additionally, another signal including three SNPs in linkage disequilibrium might be unreported susceptibility loci located in the epidermis differentiation complex region. Furthermore, two SNPs located within exon 3 of IGHM (rs45471499, P_combined = 1.15 × 10^-9) and upstream of LRP2BP (rs4317244, P_combined = 4.17 × 10^-8) were found. Moreover, rs4317244 was identified as an expression quantitative trait locus for LRP2BP that regulates tight junctions, cell cycle, and apoptosis in endothelial cell lines. Collectively, our results revealed three signals associated with systemic sclerosis in Han Chinese and suggested the importance of LRP2BP in systemic sclerosis pathogenesis. Given the limited sample size and discrepancies between previous results and our study, further studies in multiethnic populations are required for verification.

Trends in systemic sclerosis and systemic sclerosis-related pulmonary arterial hypertension mortality in the USA

There are limited data nationwide on the burden of systemic sclerosis (SSc)-related mortality. We aimed to determine recent trends in SSc and SSc-related pulmonary arterial hypertension (PAH) mortality overall and across population subgroups.

Using death certificate data from the National Center for Health Statistics, we computed the age-adjusted mortality rates of SSc and SSc-SSc−PAH, a lethal prevailing complication, across demographic groups, geographic regions and comorbid cardiorespiratory conditions, and used Joinpoint regression analysis to calculate the average annual percentage change (APC) in mortality.

From 2003 to 2016, 25 175 death records contained a code for SSc. Decedents were predominantly female (81%) and white (73%), with an average age of 66±14 years. The age-adjusted mortality rate decreased by 3% per year from 6.6 in 2003 to 4.3 per 1 000 000 population in 2016. Also, a decreasing trend was found when SSc was stratified by age, sex, race and geographic region. The prevalence of PAH was 23%. The odds of PAH were highest in female and black decedents, and in decedents with concomitant pulmonary embolism, cardiomyopathy and interstitial lung disease (ILD). SSc−PAH mortality remained stable from 2003 to 2008 then decreased by 3% per year from 2008 to 2016. In decedents with SSc−PAH, among all concomitant comorbidities, the mortality rate associated with ILD had the highest increase (average APC 6%, 95% CI 2%−10%).

The mortality rate from SSc decreased from 2003 to 2016. Decreases in mortality rates were similar across demographic groups and geographic regions. SSc−PAH-related mortality remained stable. The death rate for SSc−ILD and concomitant PAH increased during this period.

While SSc-PAH-related mortality remained stable, SSc-ILD and concomitant PAH mortality increased from 2003 to 2016http://bit.ly/3d9G0pp

HLA and autoantibodies define scleroderma subtypes and risk in African and European Americans and suggest a role for molecular mimicry

Systemic sclerosis (SSc) is a clinically heterogeneous autoimmune disease characterized by mutually exclusive autoantibodies directed against distinct nuclear antigens. We examined HLA associations in SSc and its autoantibody subsets in a large, newly recruited African American (AA) cohort and among European Americans (EA). In the AA population, the African ancestry-predominant HLA-DRB1*08:04 and HLA-DRB1*11:02 alleles were associated with overall SSc risk, and the HLA-DRB1*08:04 allele was strongly associated with the severe antifibrillarin (AFA) antibody subset of SSc (odds ratio = 7.4). These African ancestry-predominant alleles may help explain the increased frequency and severity of SSc among the AA population. In the EA population, the HLA-DPB1*13:01 and HLA-DRB1*07:01 alleles were more strongly associated with antitopoisomerase (ATA) and anticentromere antibody-positive subsets of SSc, respectively, than with overall SSc risk, emphasizing the importance of HLA in defining autoantibody subtypes. The association of the HLA-DPB1*13:01 allele with the ATA⁺ subset of SSc in both AA and EA patients demonstrated a transancestry effect. A direct correlation between SSc prevalence and HLA-DPB1*13:01 allele frequency in multiple populations was observed (r = 0.98, P = 3 × 10^-6). Conditional analysis in the autoantibody subsets of SSc revealed several associated amino acid residues, mostly in the peptide-binding groove of the class II HLA molecules. Using HLA α/β allelic heterodimers, we bioinformatically predicted immunodominant peptides of topoisomerase 1, fibrillarin, and centromere protein A and discovered that they are homologous to viral protein sequences from the Mimiviridae and Phycodnaviridae families. Taken together, these data suggest a possible link between HLA alleles, autoantibodies, and environmental triggers in the pathogenesis of SSc.

Geographic disparity in systemic sclerosis mortality in the United States: 1999–2017

Introduction:

Previous studies reported a progressive decrease in the systemic sclerosis mortality rates in the United States from 1959 to 2002. Identification of areas with clusters of higher mortality rates is important to implement targeted interventions. In this study, we aimed to estimate the mortality rates of scleroderma and to analyze its geographic variability at the state level in the United States.

Methods:

Mortality rates of scleroderma from 1999 to 2017 were obtained from the CDC Wonder Underlying Cause of Death database and its query system, using International Classification of Diseases, Tenth Revision codes. Age-adjusted rates were calculated by state and demographics. A linear regression model was applied to evaluate trends over time.

Results:

Over the period studied, a total of 24,525 deaths had scleroderma as the underlying cause of death. The age-adjusted mortality rate was 3.962 per million (95% CI: 3.912–4.012), decreasing progressively from 4.679 (95%CI: 4.423–4.934) in 1999 to 2.993 (95% CI: 2.817–3.170) per million in 2017. The age-adjusted mortality rate was 5.885 (95% CI: 5.802–5.967) and 1.651 (95% CI: 1.604–1.698) per million in females and males, respectively. Per races, the highest age-adjusted mortality rate was in Blacks or African Americans, at 5.703 per million (95% CI: 5.521–5.885), followed by American Indians or Alaska Native at 5.047 per million (95% CI: 4.428–5.667). Clusters of states with higher and lower mortality rates were identified. South Dakota had the highest whereas Hawaii had the lowest mortality rate.

Conclusion:

We found a trend to a progressive decrease in mortality rates of scleroderma during the years of our study. In addition, we found relevant state-by-state variation in mortality with several geographical clusters with higher mortality rates. Further analyses are warranted in order to better understand the factors associated with the observed geographic disparities.

Deficient Adipogenesis of Scleroderma Patient and Healthy African American Monocytes

Monocytes from systemic sclerosis (SSc, scleroderma) patients and healthy African Americans (AA) are deficient in the regulatory protein caveolin-1 leading to enhanced migration toward chemokines and fibrogenic differentiation. While dermal fibrosis is the hallmark of SSc, loss of subcutaneous adipose tissue is a lesser-known feature. To better understand the etiology of SSc and the predisposition of AA to SSc, we studied the adipogenic potential of SSc and healthy AA monocytes. The ability of SSc and healthy AA monocytes to differentiate into adipocyte-like cells (ALC) is inhibited compared to healthy Caucasian (C) monocytes. We validated that monocyte-derived ALCs are distinct from macrophages by flow cytometry and immunocytochemistry. Like their enhanced fibrogenic differentiation, their inhibited adipogenic differentiation is reversed by the caveolin-1 scaffolding domain peptide (CSD, a surrogate for caveolin-1). The altered differentiation of SSc and healthy AA monocytes is additionally regulated by peroxisome proliferator-activated receptor γ (PPARγ) which is also present at reduced levels in these cells. In vivo studies further support the importance of caveolin-1 and PPARγ in fibrogenesis and adipogenesis. In SSc patients, healthy AA, and mice treated systemically with bleomycin, adipocytes lose caveolin-1 and PPARγ and the subcutaneous adipose layer is diminished. CSD treatment of these mice leads to a reappearance of the caveolin-1+/PPARγ+/FABP4+ subcutaneous adipose layer. Moreover, many of these adipocytes are CD45+, suggesting they are monocyte derived. Tracing experiments with injected EGFP+ monocytes confirm that monocytes contribute to the repair of the adipose layer when it is damaged by bleomycin treatment. Our observations strongly suggest that caveolin-1 and PPARγ work together to maintain a balance between the fibrogenic and adipogenic differentiation of monocytes, that this balance is altered in SSc and in healthy AA, and that monocytes make a major contribution to the repair of the adipose layer.

D1398G Variant of MET Is Associated with Impaired Signaling of Hepatocyte Growth Factor in Alveolar Epithelial Cells and Lung Fibroblasts

Pulmonary fibrosis represents the terminal stage of a diverse group of lung diseases including scleroderma associated interstitial lung disease. The molecular mechanisms underlying the pathogenesis of lung fibrosis are not well understood and there is a great need for more effective treatment for this lethal disease. We recently discovered a small fragment of hepatocyte growth factor (HGF) receptor MET as a peptide designated “M10,” with strong antifibrotic properties. Furthermore, we showed that aspartic acid at position 1398 of MET is essential for M10 generation. The current study was undertaken to investigate the D1398G variant of MET in which aspartic acid at position 1398 was mutated to glycine resulting in loss of M10. We demonstrate that lung fibroblasts, A549, and primary alveolar epithelial cells (AEC) expressing D1398G MET exhibit reduced auto-phosphorylation on tyrosine residues and reduced activation of Ras and MAPK. HGF treatment of scleroderma lung fibroblasts as well as HGF treatment of TGFβ-treated normal lung fibroblasts transfected with wild type MET is associated with decreased collagen, connective tissue growth factor (CTGF, CCN2) and smooth muscle α-actin (SMA). However, HGF has no such effects in cells transfected with MET D1398G. Cisplatin- and FasL-induced apoptosis is significantly reduced in AEC transfected with MET wild type, but not in AEC transfected with MET D1398G. We conclude that the D1398G variant of MET is associated with compromised phosphorylation and impaired HGF signaling in lung fibroblasts and AEC, two cell types implicated in the pathogenesis of pulmonary fibrosis associated with scleroderma. Ongoing studies will explore the frequency of this variant and its relationship to pulmonary outcomes in scleroderma patients.

Genetics of systemic sclerosis: recent advances

Purpose of review

Large-scale and follow-up genetic association studies in systemic sclerosis (SSc) have implicated over 40 regions in disease risk, 15 of which with robust associations. Nevertheless, the causal variants and the functional mechanisms underlying the genetic associations remain elusive, and the reasons for the higher disease burden in African Americans unknown. Incorporating tools from diverse fields is beginning to unveil the role of genetic diversity and regulatory variation in SSc susceptibility. This review will summarize recent advances in SSc genetics, including autoimmune disease overlap, evidence of natural selection, and current progress towards the dissection of the functional role of associated risk variants.

Recent findings

In the past year, multiple large-scale studies reported novel strong and suggestive SSc associations. These results, coupled with the regions shared with other autoimmune diseases, emphasize the role of dysregulation of immune pathways as a key causative factor in SSc pathogenesis. Strong evidence implicates natural selection as a mechanism contributing to the maintenance of some of these SSc alleles in the population. Studies integrating genomic, transcriptomic, and epigenomic datasets in specific cell types to identify causal autoimmune disease variants are emerging.

Summary

The identification and comprehensive understanding of the factors and mechanisms contributing to SSc will contribute to improved diagnosis and disease management.

Recent advances in the genetics of systemic sclerosis: toward biological and clinical significance

Significant advances have been made in understanding the genetic basis of systemic sclerosis (SSc) in recent years. Genomewide association and other large-scale genetic studies have identified 30 largely immunity-related genes which are significantly associated with SSc. We review these studies, along with genomewide expression studies, proteomic studies, genetic mouse models, and insights from rare sclerodermatous diseases. Collectively, these studies have begun to identify pathways that are relevant to SSc pathogenesis. The findings presented in this review illustrate how both genetic and genomic aberrations play important roles in the development of SSc. However, despite these recent discoveries, there remain major gaps between current knowledge of SSc, a unified understanding of pathogenesis, and effective treatment. To this aim, we address the important issue of SSc heterogeneity and discuss how future research needs to address this in order to develop a clearer understanding of this devastating and complex disease.

Enhanced chemokine-receptor expression, function, and signaling in healthy African American and scleroderma-patient monocytes are regulated by caveolin-1

Background

A major health disparity suffered by African Americans (AA) is a predisposition toward fibrotic diseases of the skin, lung, and other organs. We previously showed that healthy AA and scleroderma (systemic sclerosis (SSc)) patient monocytes share biochemical and functional differences from control Caucasian (C) monocytes that may predispose AA to SSc. The central difference is a decrease in caveolin-1. Low caveolin-1 levels promote monocyte migration, their differentiation into fibrocytes, and fibrocyte recruitment into fibrotic tissues. Here we have greatly expanded our studies on the mechanism of action in fibrosis of caveolin-1 in AA and SSc monocytes.

Results

Expression of chemokine receptors (CCR1, CCR2, CCR3) is enhanced in healthy AA monocytes compared to healthy C monocytes and further increased in SSc monocytes. A parallel increase in function occurs assessed by migration toward chemokines MCP-1 and MCP-3. Chemokine-receptor expression and function are inhibited by the caveolin-1 scaffolding domain peptide (CSD) via its action as a surrogate for caveolin-1. Cells bearing chemokine receptors accumulate to high levels in fibrotic lung and skin tissue from SSc patients and from mice treated with bleomycin. This accumulation is almost completely blocked in mice treated with CSD. In signaling studies, Src activation is enhanced in AA monocytes compared to C monocytes and further increased in SSc monocytes. Lyn is also highly activated in SSc monocytes. Src and Lyn activation are inhibited by CSD. Src and Lyn’s roles in monocyte migration were demonstrated using specific inhibitors.

Conclusions

To the best of our knowledge, this is the first report that the expression and function of CCR1, CCR2, and CCR3 are upregulated in monocytes from healthy AA and from SSc patients via molecular mechanisms involving caveolin-1, Src/Lyn, and MEK/ERK. The results suggest that the migration/recruitment of monocytes and fibrocytes into fibrotic tissues, mediated at least in part by CCR1, CCR2, and CCR3, plays a major role in the progression of lung and skin fibrosis and in the predisposition of AA to fibrotic diseases. Our findings further suggest that chemokine receptors and signaling molecules, particularly caveolin-1, that control their expression/function are promising targets for treating fibrotic diseases.

Electronic supplementary material

The online version of this article (doi:10.1186/s13069-015-0028-7) contains supplementary material, which is available to authorized users.

Caveolin-1 deficiency may predispose African Americans to systemic sclerosis-related interstitial lung disease

OBJECTIVE

Interstitial lung disease (ILD) is the leading cause of death in patients with systemic sclerosis (SSc; scleroderma). Although SSc-related ILD is more common and severe in African Americans than in Caucasians, little is known about factors underlying this significant health disparity. The aim of this study was to examine the role that low expression of caveolin-1 might play in susceptibility to ILD among African Americans.

METHODS

Assays of monocyte migration toward stromal cell-derived factor 1 (SDF-1) were performed using monocytes from Caucasian and African American healthy donors and patients with SSc. For fibrocyte differentiation studies, total peripheral blood mononuclear cells were incubated on fibronectin-coated plates. Protein expression was evaluated by immunohistochemistry and Western blotting.

RESULTS

Monocytes from healthy African American donors and those from patients with SSc had low caveolin-1 levels, enhanced migration toward the CXCR4 ligand SDF-1, and enhanced differentiation to fibrocytes. Enhanced migration and differentiation of monocytes from African Americans and patients with SSc appeared to be attributable to the lack of caveolin-1, because restoring caveolin-1 function using a caveolin-1 scaffolding domain peptide inhibited these processes. Although they differed from monocytes from Caucasians, monocytes from both African Americans and patients with SSc were not identical, because SSc monocytes showed major increases from baseline in ERK, JNK, p38, and Smad2/3 activation, while monocytes from African Americans showed only limited ERK activation and no activation of JNK, p38, or Smad2/3. In contrast, SDF-1 exposure caused no additional ERK activation in SSc monocytes but did cause significant additional activation in monocytes from African Americans.

CONCLUSION

African Americans may be predisposed to SSc-related ILD due to low baseline caveolin-1 levels in their monocytes, potentially affecting signaling, migration, and fibrocyte differentiation. The monocytes of African Americans may lack caveolin-1 due to high levels of transforming growth factor β in their blood.

Systemic sclerosis evolution of disease pathomorphosis and survival. Our experience on Italian patients' population and review of the literature

The clinical spectrum and prognosis of systemic sclerosis (SSc) seem to vary among patients' populations recruited during different time periods. In order to verify this possible evolution we investigated the clinico-serological and survival rate in a large Italian SSc series (821 patients; 746 females, 75 males; mean age 53.7±13.9SD years) recruited between 2000 and 2011. The observed findings were compared with previous studies of the world literature.Compared to older Italian SSc series, the present patients' population showed a significantly increased prevalence of limited cutaneous SSc (from 72 to 87.5%; p ≤.0001) and serum anti-centromere antibodies (from 39 to 47,4%; p ≤.001), with a significant reduction of lung (from 81 to 63.7%; p ≤.0001), heart (from 35 to 20.5%; p ≤.0001), and renal involvement (from 10 to 3.8%; p ≤.0001), and skin ulcers (from 54 to 16.5%; p ≤.0001). Cumulative 10th-year survival showed a clear-cut increase (80.7%) compared to our previous series (69.2%). These findings were mirrored by the results of survival studies published during the last five decades, grouped according to the time periods of patients'' recruitment at the referral centers. A clear progression of 10th-year survival rates was detectable, from the 54% median survival of the oldest studies (1935-1974) to 74% and 83.5% of the more recent SSc series, 1976-1999 and after 1999, respectively. In conclusion, the favorable evolution of SSc pathomorphosis and prognosis during the last decades might be related to more diffuse physician/patient awareness of this harmful disease and availability of diagnostic tools, the consequent wider recruitment of patients in the early stages of the disease, as well as to the improved therapeutic strategies.

Derivation and validation of a prediction rule for two-year mortality in early diffuse cutaneous systemic sclerosis

OBJECTIVE

Systemic sclerosis (SSc) is associated with a reduction in life expectancy, but there are no validated prognostic models for determining short-term mortality. The objective of this study was to derive and validate a prediction rule for 2-year mortality in patients with early diffuse cutaneous SSc (dcSSc).

METHODS

We studied a prospectively enrolled cohort of 387 US Caucasian patients with early dcSSc (<2 years from the appearance of the first symptom), randomly divided into a derivation cohort (n = 260) and a validation cohort (n = 127). Predefined baseline predictor variables were analyzed in a stepwise multivariable logistic regression model in order to identify factors independently associated with 2-year all-cause mortality using a cutoff of P < 0.05. We rounded the beta values to the nearest integer and summed the points assigned to each variable in order to stratify patients into low-risk, moderate-risk, and high-risk groups. We then applied this rule to an external validation cohort of 110 Caucasian patients with early dcSSc from a single UK center and compared stratum-specific mortality using chi-square statistics.

RESULTS

Four independent predictor variables (with assigned integer values) comprised the model: age at first visit (points allotted: -1, 0, or 1), skin thickness progression rate (points allotted: 0 or 1), gastrointestinal tract severity (points allotted: 0, 1, or 2), and anemia (points allotted: 0 or 2). The prediction model performed well, with no significant differences between the derivation cohort and the US or UK validation cohorts in the low-risk and moderate-risk groups.

CONCLUSION

We derived a 4-variable prediction rule that can be used to stratify patients with early dcSSc into groups by risk of 2-year mortality, and we validated that prediction rule in US and UK cohorts.

Mortality and survival in systemic sclerosis: systematic review and meta-analysis

OBJECTIVE

To determine the mortality, survival, and causes of death in patients with systemic sclerosis (SSc) through a meta-analysis of the observational studies published up to 2013.

METHODS

We performed a systematic review and meta-analysis of the observational studies in patients with SSc and mortality data from entire cohorts published in MEDLINE and SCOPUS up to July 2013.

RESULTS

A total of 17 studies were included in the mortality meta-analysis from 1964 to 2005 (mid-cohort years), with data from 9239 patients. The overall SMR was 2.72 (95% CI: 1.93-3.83). A total of 43 studies have been included in the survival meta-analysis, reporting data from 13,529 patients. Cumulative survival from onset (first Raynaud's symptom) has been estimated at 87.6% at 5 years and 74.2% at 10 years, from onset (non-Raynaud's first symptom) 84.1% at 5 years and 75.5% at 10 years, and from diagnosis 74.9% at 5 years and 62.5% at 10 years. Pulmonary involvement represented the main cause of death.

CONCLUSIONS

SSc presents a larger mortality than general population (SMR = 2.72). Cumulative survival from diagnosis has been estimated at 74.9% at 5 years and 62.5% at 10 years. Pulmonary involvement represented the main cause of death.

Racial differences between blacks and whites with systemic sclerosis

PURPOSE OF REVIEW

Racial disparities appear to exist in the susceptibility and severity of systemic sclerosis (SSc, scleroderma) and are responsible for a greater health burden in blacks as compared with whites. Disparities in socioeconomic status and access to healthcare do not sufficiently explain the observed differences in prevalence and mortality. It is important to determine whether there might be a biologic basis for the racial disparities observed in SSc.

RECENT FINDINGS

We present data to suggest that the increased susceptibility and severity of SSc in blacks may result in part from an imbalance of profibrotic and antifibrotic factors. Racial differences in the expression of transforming growth factor-β1 (TGF-β1) and caveolin-1, as well as differences in the expression of hepatocyte growth factor and PPAR-γ, have been demonstrated in blacks with SSc, as well as in normal black individuals. A genetic predisposition to fibrosis may account for much of the racial disparities between black and white patients with SSc.

SUMMARY

A better understanding of the biologic basis for the racial disparities observed in SSc may lead to improved therapies, along with the recognition that different therapies may need to be adapted for different groups of patients.

Trends in mortality in patients with systemic sclerosis over 40 years: a systematic review and meta-analysis of cohort studies

OBJECTIVE

SSc is known as the most severe connective tissue disorder, and to be associated with a high mortality risk. Some improvements in therapy for SSc have been achieved in recent years and some preliminary data have suggested an improvement in patient survival. Thus, we set out to determine whether mortality rate in SSc patients has decreased over the past 40 years through a meta-analysis of cohort studies.

METHODS

We performed a systematic review and a meta-analysis of literature in MEDLINE and Embase databases from January 1960 to June 2010. All cohort studies reporting on SSc mortality were analysed. We then calculated pooled standardized mortality ratios (SMRs) of SSc mortality and calculated their changes over time using meta-regression analysis.

RESULTS

Nine studies were included, corresponding to a total of 2691 SSc patients. The pooled SMR was 3.53 [95% CI 3.03, 4.11, P < 0.0001; I(2 )= 93%, P(het) = 0.001]. Mid-cohort year ranged from 1977 to 1995 (before 1980: two studies; 1980-90: five studies; and after 1990: two studies): adjusted meta-regression analysis did not show significant change in SMR over time (P = 0.523). Among 732 deaths, heart involvement was the most frequent cause of deaths (29%) followed by lung involvement.

CONCLUSION

Our results confirm that SSc is a devastating condition as reflected by a pooled SMR of 3.5. Additionally, SMR has not significantly changed over the past 40 years. Further studies are needed to assess the effect of the most recent available therapies on mortality in SSc.

Apoptosis modulation as a promising target for treatment of systemic sclerosis

Diffuse systemic sclerosis (SSc) is a fatal autoimmune disease characterized by an excessive ECM deposition inducing a loss of function of skin and internal organs. Apoptosis is a key mechanism involved in all the stages of the disease: vascular damage, immune dysfunction, and fibrosis. The purpose of this paper is to gather new findings in apoptosis related to SSc, to highlight relations between apoptosis and fibrosis, and to identify new therapeutic targets.

Determinants of work disability in patients with systemic sclerosis: a longitudinal study of the GENISOS cohort

OBJECTIVES

To determine the prevalence, correlates, and predictors of work disability (WD) in the Genetics versus ENvironment In Scleroderma Outcome Study (GENISOS). We hypothesized that WD in systemic sclerosis (SSc) is a function of demographic, clinical, and psychosocial factors.

METHODS

Patients enrolled in the GENISOS cohort were subdivided in 3 groups: work disabled, working, and retired or homemakers. The latter group (n = 29) was excluded from further analysis. We used logistic regression analysis with a forward hierarchical variable selection strategy to investigate the independent correlates of WD at enrollment. Cox regression proportional Hazard's model with a similar variable selection strategy was utilized to determine the predictors of WD in those working at enrollment.

RESULTS

Overall, 284 patients with a mean age of 48.7 years and disease duration of 2.5 (±1.6) years were enrolled into the GENISOS cohort, consisting of 83.5% female, 46.8% white, 28.9% Hispanic, and 20.4% African American. Patients were longitudinally followed in 1438 study visits. At enrollment, 124 patients (43.7%) were work disabled, whereas 131 (46.1%) were working. Lower level of education (P < 0.001), higher Medsger Lung Severity Index (P = 0.012), higher Fatigue Severity Score (P = 0.008), and less social support (P < 0.001) correlated independently with WD. Of those working at baseline, 35 (26.7%) eventually developed WD. Non-white ethnicity (P = 0.038), lower DLCO % predicted value (P = 0.038), and higher Fatigue Severity Score (P = 0.009) at enrollment independently predicted WD on follow-up visits.

CONCLUSIONS

WD is a major problem among SSc patients and its prevalence is substantially higher than other rheumatic conditions. Demographic, clinical, and psychosocial factors correlate with WD cross-sectionally and predict WD longitudinally in these patients.

Gender and ethnicity differences in patients with diffuse systemic sclerosis--analysis from three large randomized clinical trials

OBJECTIVE

Although the incidence of dcSSc is higher in African-American and Hispanic populations compared with European Caucasian patients, it is not clear whether there are differences in subsequent disease course. Also, the potential impact of gender on the disease course of dcSSc is not well defined. Our objective was to assess the course of modified Rodnan skin score (MRSS), HAQ-disability index (HAQ-DI) and forced vital capacity per cent (FVC%) predicted between men vs women and three ethnic groups with dcSSc participating in three randomized clinical trials (RCTs).

METHOD

Data from RCTs (n = 495) were pooled and analysed. Baseline characteristics were compared in men vs women and among ethnic groups. A linear mixed effects model was used to assess the predictors of MRSS, HAQ-DI and FVC%. The primary independent variables were time-in-study and its interaction with gender and ethnicity. The models were adjusted for other covariates that were significant at baseline between gender and ethnicity analyses.

RESULTS

Men had lower HAQI-DI scores compared with women (P < 0.05). Among the three ethnic groups, Caucasians were older, African-Americans had lower FVC% predicted and Hispanics had greater tender joint counts (P < 0.05). The course of MRSS, HAQ-DI and FVC% predicted during the study period was not significantly different between gender and three ethnicities. Time-in-study was an independent predictor of improvement in MRSS and HAQ-DI.

CONCLUSION

Our analysis explores the influence of gender and ethnicity on disease course in RCTs. These findings are relevant to issues of future trial design.

Predictors of interstitial lung disease in early systemic sclerosis: a prospective longitudinal study of the GENISOS cohort

INTRODUCTION

The objective of the present study was to examine the association of baseline demographic and clinical characteristics with sequentially obtained measurements of forced vital capacity (FVC), expressed as a percentage of the predicted value, and to identify predictors of the decline rate in FVC over time in the Genetics versus Environment in Scleroderma Outcome Study (GENISOS).

METHODS

To date, 266 patients have been enrolled in GENISOS, a prospective, observational cohort of patients with early systemic sclerosis. In addition to pulmonary function tests (PFTs), clinical and laboratory data were obtained from each patient. We analyzed 926 FVC measurements utilizing generalized linear mixed models. The predictive significance of baseline variables for the decline rate in FVC was investigated by the interaction term between the variable and the follow-up time within the first 3 years after enrollment as well as throughout the entire follow-up time.

RESULTS

The cohort consisted of 125 white, 54 African American, and 77 Hispanic patients with average disease duration of 2.5 years at enrollment. The mean follow-up time was 3.8 years, ranging up to 11.4 years. A number of baseline variables, including antibody status, African American ethnicity, disease type, baseline PFT values, modified Rodnan Skin Score, fibrosis on chest radiograph, and lung and skin subscores of the Severity Index, were associated with serially measured FVC levels. However, only the presence of anti-topoisomerase I antibodies (ATA) was associated with lower FVC levels (P < 0.001) as well as accelerated decline rate in FVC within the first 3 years of follow-up (P = 0.02). None of the baseline variables predicted the rate of decline in FVC on long-term follow-up. Patients with rapidly progressive ILD, however, were under-represented in the long-term follow-up group because the accelerated rate of decline in FVC was associated with poor survival (P = 0.001).

CONCLUSIONS

Presence of ATA was the only baseline variable associated with differential FVC levels, predicting the rate of decline in FVC within the first 3 years of follow-up. The association of faster decline in FVC with poor survival further emphasizes the need for identification of predictive biomarkers by collection of genetic information and serial blood samples in cohort studies.

Clinical and genetic factors predictive of mortality in early systemic sclerosis

OBJECTIVE

To investigate the clinical and genetic variables at initial presentation that predict survival in the Genetics versus Environment in Scleroderma Outcome Study (GENISOS) cohort.

METHODS

GENISOS is a prospective, observational study of a multiethnic early systemic sclerosis (SSc) cohort. To date, a total of 250 patients have been enrolled. In addition to clinical and laboratory data, electrocardiograms (EKGs), chest radiographs, and pulmonary function tests have been obtained from each patient. A modified Rodnan skin thickness score, HLA class II genotyping, and a Medsger Damage Index also have been collected. We performed multivariable analyses utilizing the Cox regression following a purposeful model building strategy.

RESULTS

The study analyzed 122 white, 47 African American, and 71 Hispanic SSc patients with an average disease duration of 2.6 years at enrollment. At the time of analysis, 52 (20.8%) of the 250 patients had died. In the final multivariable model excluding HLA genes, 7 variables emerged as significant predictors of mortality: age > or =65 years at enrollment, forced vital capacity <50% predicted, clinically significant arrhythmia on EKG, absence of anticentromere antibodies, hypertension, chest radiograph suggestive of pulmonary fibrosis, and low body mass index (BMI). In separate modeling that included HLA genes, HLA alleles DRB1*0802 and DQA1*0501 were significant predictors of mortality in addition to the predictors mentioned above.

CONCLUSION

A limited number of variables collected at presentation, including BMI, are able to predict mortality in patients with early SSc. In addition, some of the HLA genes associated with SSc susceptibility are useful for predicting SSc outcome.

Gastrointestinal manifestations of systemic sclerosis

Systemic sclerosis is a chronic disorder of connective tissue that affects the gastrointestinal tract in more than 80% of patients. Changes in neuromuscular function with progressive fibrosis of smooth muscle within the muscularis propria impair normal motor function, which may secondarily alter transit and nutrient absorption. Esophageal manifestations with gastroesophageal reflux and dysphagia are the most common visceral manifestation of the disease, often requiring more intense acid-suppressive medication. Gastric involvement may lead to gastroparesis, which can be found in up to 50% of patients. Severe small bowel disease can present as chronic intestinal pseudo-obstruction with distended loops of small intestine, bacterial overgrowth, impaired absorption and progressive development of nutritional deficiencies. While not studied as extensively, systemic sclerosis often also affects colorectal function resulting in constipation, diarrhea or fecal incontinence. Nutritional support and prokinetics have been used with some success to manage gastric and small or large bowel involvement in patients with systemic sclerosis. Despite advances in management, significant gastrointestinal manifestations of systemic sclerosis still carry a poor prognosis with a five-year mortality exceeding 50%.

Down-regulation of collagen and connective tissue growth factor expression with hepatocyte growth factor in lung fibroblasts from white scleroderma patients via two signaling pathways

OBJECTIVE

To study the mechanisms by which hepatocyte growth factor (HGF) down-regulates collagen and connective tissue growth factor (CTGF) in scleroderma (systemic sclerosis [SSc]) lung fibroblasts.

METHODS

CTGF, type I collagen, and IkappaBalpha expression, together with MAPK phosphorylation, were studied by immunoblotting of lung fibroblasts derived from white SSc patients. Matrix metalloproteinase 1 (MMP-1) expression in cell culture medium samples was measured by enzyme-linked immunosorbent assay, MMP-1 activity was studied using an MMP-1 assay, and NF-kappaB DNA binding activity was determined using a transcription factor assay.

RESULTS

In lung fibroblasts from white SSc patients, HGF activated MAPK (ERK-1/2) signaling pathways and MMP-1, while it inhibited NF-kappaB and significantly down-regulated CTGF and collagen in a time- and dose-dependent manner. Small interfering RNA (siRNA)-mediated depletion of Grb2 expression disrupted c-Met receptor downstream signaling, which resulted in diminished HGF-induced ERK-1/2 phosphorylation and the recovery of HGF-inhibited expression of MMP-1, NF-kappaB, collagen, and CTGF. The MAPK inhibitor, U0126, blocked MMP-1 activity and restored HGF-inhibited collagen and CTGF accumulation. Inhibition of MMP activity by MMP inhibitor GM1489 and inhibition of MMP-1 expression by siRNA did not prevent HGF-induced ERK-1/2 phosphorylation and NF-kappaB activity, but significantly restored HGF-inhibited collagen and CTGF accumulation. NF-kappaB inhibitor BAY 11-7082 did not interfere with MAPK phosphorylation or MMP-1 expression and activation, but significantly inhibited NF-kappaB DNA binding activity and acted synergistically with HGF to completely diminish the expression of CTGF.

CONCLUSION

In lung fibroblasts from white SSc patients, HGF down-regulates the accumulation of CTGF via MAPK/MMP-1 and NF-kappaB signaling pathways, whereas collagen down-regulation is mediated mainly by a MAPK/MMP-1-dependent pathway.

Systemic sclerosis mortality in the United States: 1999-2002 implications for patient care

OBJECTIVE

To describe the systemic sclerosis mortality rates in the United States between 1999 and 2002, a time period in which a new coding system was used to record deaths, and to describe its implications in patient care.

METHODS

We used the mortality database from the National Center of Health Statistics and with the use of ICD-10 codes for systemic sclerosis calculated death rates by gender, race, age, state, and region for the United States. Death rates are expressed as per million population.

RESULTS

Age-adjusted death rates for systemic sclerosis were 6.8 cases per million in women, 2.1 cases per million in men, and 4.7 cases per million for the whole population. Death rates peaked a decade earlier in the African American population when compared with those in the white population (65-74 vs. 75-84 years of age). Age-adjusted mortality was highest in African American women at 9.5 cases per million.

CONCLUSION

Mortality rates for systemic sclerosis are slightly higher since the implementation of the new disease-specific ICD-10 coding system for recording deaths. Death rates related to systemic sclerosis among the African American population are remarkably higher than those among the white population; this is believed to be related to the more aggressive disease seen in the African American patients and to the disparity of healthcare resources. These findings suggest that earlier and more aggressive treatment is warranted in the African American population, with more frequent follow-up and preventive care.

Impairment of the antifibrotic effect of hepatocyte growth factor in lung fibroblasts from African Americans: possible role in systemic sclerosis

OBJECTIVE

To compare the composition of cytokines in African American and Caucasian patients with systemic sclerosis (SSc; scleroderma) and in healthy individuals, particularly the expression and function of hepatocyte growth factor (HGF).

METHODS

Bronchoalveolar lavage (BAL) fluid samples were analyzed using cytokine array techniques. HGF in plasma and cell culture medium samples was measured by enzyme-linked immunosorbent assay. Connective tissue growth factor (CTGF), type I collagen expression, and c-Met receptor phosphorylation were studied by immunoblotting.

RESULTS

Overall greater expression of cytokines in BAL fluid from African American patients as compared with Caucasian patients was observed. Significant increases in HGF concentrations were detected in BAL fluid, plasma, and fibroblast culture medium from Caucasian SSc patients. In contrast, African American SSc patients did not demonstrate an increase in HGF. Recombinant HGF readily abolished CTGF expression and collagen accumulation in lung fibroblasts isolated from Caucasian SSc patients. Pretreatment of lung fibroblasts with neutralizing anti-c-Met antibody abolished the effects of HGF on CTGF expression and collagen accumulation, suggesting that the antifibrotic activity of HGF is mediated via c-Met receptor tyrosine kinase. Whereas recombinant HGF rapidly induced c-Met receptor phosphorylation in lung fibroblasts from Caucasian patients, c-Met receptor phosphorylation was significantly reduced in lung fibroblasts from African American subjects. Moreover, recombinant HGF failed to prevent CTGF expression and collagen accumulation in lung fibroblasts derived from African American subjects.

CONCLUSION

Ethnic differences exist in terms of antifibrotic HGF expression in lung fibroblasts derived from Caucasian and African American subjects. Reduced levels of HGF as well as a deficiency in c-Met receptor function appear to be present in African American patients with SSc. These findings may explain in part the greater disease severity and worse prognosis observed in African Americans with SSc.

Update on Connective Tissue Diseases in Dermatology

Recent advances in understanding the pathogenesis of autoimmune diseases, including lupus erythematosus, dermatomyositis, and scleroderma, have allowed for reorganization of the classification of these disorders. With these novel stratifications, early identification of rheumatic skin diseases with systemic implications and consistency in designing and executing therapeutic trials will be enhanced. This review will provide a compilation of updates on epidemiology, pathology, evaluation, and classification with a predominant focus on therapeutics, reflecting the growth is this area.