Association of functional microsatellites in the human type I collagen alpha2 chain (COL1A2) gene with systemic sclerosis

Histopathological and molecular analysis in dermis and epidermis of patients with systemic and localized scleroderma

OBJECTIVE

Scleroderma has a wide range of clinical manifestations due to vasculopathy, autoimmunity, altered endothelium function, and abnormal fibrosis, which are accused in the pathogenesis of the disease. The aim of this study is to shed light on the pathogenesis of the disease in childhood via dermal immunohistochemical analysis of the cases.

METHODS

A single-blind clinical trial is conducted with evaluation of the tissue samples obtained from patients. The samples are stained with PAS, hematoxylin and eosin, E-Cadherin, Connective tissue growth factor (CTGF), Tunnel, and staining for Transforming growth factor beta 1 (TGF-β1) and evaluated by light microscopy. In addition, both TGF-β1 level and mRNA expression analyses in plasma and tissue samples from patients are performed. A total of 15 patients (systemic, n=8 or localized; n=7) were enrolled in the study.

RESULTS

The mean age of onset of the disease was 9.2±1.2 years, and the mean age of diagnosis was 15.3±3.2 years. Antinuclear antibody (ANA) titer was between 1/160-1/640 in all patients with systemic sclerosis. There was no ANA positivity in patients with localized scleroderma. A total of 22 tissue samples (15 diseased tissues, 7 healthy tissues) were examined. Histopathological examination has shown that two clinically different subgroups have different characteristics at the tissue level.

CONCLUSION

TGF-β1 levels, which play a fundamental role in the pathogenesis of the disease, are found in both plasma and skin have been shown high. This elevation was found particularly in patients with systemic scleroderma to be more pronounced. Also, in patients with localized scleroderma, skin fibroblasts have been shown to limit the pathologic response.

Analysis of differentially expressed genes related to cerebral ischaemia in young rats based on the Gene Expression Omnibus database

BACKGROUND

The incidence rate of cerebral infarction in young people is increasing day by day, the age of onset tends to be younger, and its internal pathogenesis and mechanism are very complicated, which leads to greater difficulties in treatment. Therefore, it is essential to analyze the key pathway that affects the onset of cerebral infarction in young people from the perspective of genetics.

AIM

To compare the differentially expressed genes in the brain tissue of young and aged rats with middle cerebral artery occlusion and to analyse their effect on the key signalling pathway involved in the development of cerebral ischaemia in young rats.

METHODS

The Gene Expression Omnibus 2R online analysis tool was used to analyse the differentially expressed genes in the GSE166162 dataset regarding the development of cerebral ischaemia in young and aged groups of rats. DAVID 6.8 software was further used to filter the differentially expressed genes. These genes were subjected to Gene Ontology (GO) function analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis to determine the key gene pathway that affects the occurrence of cerebral ischaemia in young rats.

RESULTS

Thirty-five differentially expressed genes (such as Igf2, Col1a2, and Sfrp1) were obtained; 73 GO enrichment analysis pathways are mainly involved in biological processes such as drug response, amino acid stimulation response, blood vessel development, various signalling pathways, and enzyme regulation. They are involved in molecular functions such as drug binding, protein binding, dopamine binding, metal ion binding, and dopamine neurotransmitter receptor activity. KEGG pathway enrichment analysis showed a significantly enriched pathway: The cyclic adenosine monophosphate (c-AMP) signalling pathway.

CONCLUSION

The c-AMP signalling pathway might be the key pathway in the intervention of cerebral infarction in young people.

Updates on genetics in systemic sclerosis

Systemic sclerosis (SSc) is a complex disease, in which an interaction of genetic and environmental factors plays an important role in its development and pathogenesis. A number of genetic studies, including candidate gene analysis and genome-wide association study, have found that the associated genetic variants are mainly localized in noncoding regions in the expression quantitative trait locus and influence corresponding gene expression. The gene variants identified as a risk for SSc susceptibility include those associated with innate immunity, adaptive immune response, and cell death, while there are only few SSc-associated genes involved in the fibrotic process or vascular homeostasis. Human leukocyte antigen class II genes are associated with SSc-related autoantibodies rather than SSc itself. Since the pathways between the associated genotype and phenotype are still poorly understood, further investigations using multi-omics technologies are necessary to characterize the complex molecular architecture of SSc, identify biomarkers useful to predict future outcomes and treatment responses, and discover effective drug targets.

Genetic variations at the human growth hormone receptor (GHR) gene locus are associated with idiopathic short stature

GH plays an essential role in the growing child by binding to the growth hormone receptor (GHR) on target cells and regulating multiple growth promoting and metabolic effects. Mutations in the GHR gene coding regions result in GH insensitivity (dwarfism) due to a dysfunctional receptor protein. However, children with idiopathic short stature (ISS) show growth impairment without GH or GHR defects. We hypothesized that decreased expression of the GHR gene may be involved. To test this, we investigated whether common genetic variants (microsatellites, SNPs) in regulatory regions of the GHR gene region were associated with the ISS phenotype. Genotyping of a GT‐repeat microsatellite in the GHR 5′UTR in a Montreal ISS cohort (n = 37 ISS, n = 105 controls) revealed that the incidence of the long/short (L/S) genotype was 3.3× higher in ISS children than controls (P = 0.04, OR = 3.85). In an Italian replication cohort (n = 143 ISS, n = 282 controls), the medium/short (M/S) genotype was 1.9× more frequent in the male ISS than controls (P = 0.017, OR = 2.26). In both ISS cohorts, logistic regression analysis of 27 SNPs showed an association of ISS with rs4292454, while haplotype analysis revealed specific risk haplotypes in the 3′ haploblocks. In contrast, there were no differences in GT genotype frequencies in a cohort of short stature (SS) adults versus controls (CARTaGENE: n = 168 SS, n = 207 controls) and the risk haplotype in the SS cohort was located in the most 5′ haploblock. These data suggest that the variants identified are potentially genetic markers specifically associated with the ISS phenotype.

The role of TGF-β in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common endocrine disorder characterized by chronic oligoanovulation and hyperandrogenism and associated with insulin resistance, type 2 diabetes, and cardiovascular risk. In recent years, genetic studies have linked PCOS to a dinucleotide marker D19S884 in the fibrillin 3 gene. Fibrillins make up the major component of microfibrils in the extracellular matrix (ECM) and interact with molecules in the ECM to regulate transforming growth factor β (TGF-β) signaling. Therefore, variations in fibrillin 3 and subsequent dysregulation of TGF-β may contribute to the pathogenesis of PCOS. Here, we review the evidence from genetic studies supporting the role of TGF-β in PCOS and describe how TGF-β dysregulation may contribute to (1) the fetal origins of PCOS, (2) reproductive abnormalities in PCOS, and (3) cardiovascular and metabolic abnormalities in PCOS.

Mapping QTL affecting a systemic sclerosis-like disorder in a cross between UCD-200 and red jungle fowl chickens

Systemic sclerosis (SSc) or scleroderma is a rare, autoimmune, multi-factorial disease characterized by early microvascular alterations, inflammation, and fibrosis. Chickens from the UCD-200 line develop a hereditary SSc-like disease, showing all the hallmarks of the human disorder, which makes this line a promising model to study genetic factors underlying the disease. A backcross was generated between UCD-200 chickens and its wild ancestor - the red jungle fowl and a genome-scan was performed to identify loci affecting early (21 days of age) and late (175 days of age) ischemic lesions of the comb. A significant difference in frequency of disease was observed between sexes in the BC population, where the homogametic males were more affected than females, and there was evidence for a protective W chromosome effect. Three suggestive disease predisposing loci were mapped to chromosomes 2, 12 and 14. Three orthologues of genes implicated in human SSc are located in the QTL region on chromosome 2, TGFRB1, EXOC2-IRF4 and COL1A2, as well as CCR8, which is more generally related to immune function. IGFBP3 is also located within the QTL on chromosome 2 and earlier studies have showed increased IGFBP3 serum levels in SSc patients. To our knowledge, this study is the first to reveal a potential genetic association between IGFBP3 and SSc. Another gene with an immunological function, SOCS1, is located in the QTL region on chromosome 14. These results illustrate the usefulness of the UCD-200 chicken as a model of human SSc and motivate further in-depth functional studies of the implicated candidate genes.

Annual Medical Costs and Healthcare Resource Use in Patients with Systemic Sclerosis in an Insured Population

Objective.

Systemic sclerosis (SSc) is a chronic autoimmune disease. The objective of our study was to estimate the medical costs and healthcare resource use of subjects with SSc in a large US managed care plan.

Methods.

Subjects at least 18 years of age and with claims-based evidence of SSc (ICD-9-CM code 710.1x) were identified from a health plan database from 2003 through 2008. Subjects were matched to unaffected controls, based on index date, age, sex, geographic region, time on insurance, and comorbidity score. Costs and resource use were identified during the 12-month postindex period. A generalized linear model (GLM) was used to estimate costs, controlling for demographic and clinical characteristics.

Results.

In this study, 1648 subjects with SSc were matched to 4944 controls. Mean overall annual medical costs were higher among SSc subjects than controls ($17,365 vs $5,508; p < 0.001). A GLM model supported these results. Evidence of lung disease, gastrointestinal bleeding, or renal disease increased costs (all p < 0.001). Compared to controls, significantly higher proportions of SSc subjects had postindex ambulatory visits, emergency department visits, and inpatient hospital stays (all p < 0.001).

Conclusion.

Our findings suggest that the medical costs and resource use associated with treating SSc are high (compared to matched controls), and as expected, subjects with serious disease complications experience the highest costs.

Genetic susceptibility to systemic sclerosis from clinical aspect to genetic factor analyses

BACKGROUND

Systemic sclerosis is a rare autoimmune disease mainly characterized by vascular alteration and fibrosis involving skin but also visceral organs such as lungs, digestive tract, and heart. This disease leads to high morbidity and mortality. Its pathogenesis remains unclear, but recent attention has focus on genetic factors.

OBJECTIVE

We first recall the main manifestations associated with systemic sclerosis and leading to its diagnosis and prognosis. Then we propose an overview on human genetics studies, as a number of genetic loci have been identified that appear to be associated with the disease.

METHODS

Articles concerning association studies with candidate genes encoding for extracellular matrix proteins, cytokines, growth factors, chemokines, and proteins involved in vascular tone and immune regulations are presented and discussed.

RESULTS/CONCLUSION

Systemic sclerosis is a multigenic complex disorder. Genetic associations are observed in distinct phenotypes such as the diffuse cutaneous form or the limited form, or in association with specific autoantibody pattern. Promising candidate genes are those involved in pathways that lead to the vascular damage and fibrosis. A better knowledge of crucial mediators involved in systemic sclerosis could in the future provide new therapeutic strategies to control the disease.

Identification of a polycystic ovary syndrome susceptibility variant in fibrillin-3 and association with a metabolic phenotype

CONTEXT

Polycystic ovary syndrome (PCOS), the most common reproductive endocrine disorder of premenopausal women, is also associated with metabolic abnormalities including insulin resistance and an increased risk for diabetes mellitus. We previously mapped a PCOS susceptibility locus to chromosome 19p13.2 near the dinucleotide repeat marker D19S884.

OBJECTIVE

Our objective is to localize the chromosome 19p13.2 PCOS susceptibility locus and determine its impact on metabolic features of PCOS.

DESIGN

Resequencing and family-based association testing were used to examine the effect of sequence variation within 100 kb of D19S884 on the reproductive and metabolic phenotypes of PCOS.

SETTING

The study was conducted in an academic medical center.

SUBJECTS

Genetic analyses were performed on DNA obtained from1723 individuals in 412 families with 412 index cases and 43 affected sisters of predominantly European origin (>94%). Genotype-phenotype associations were assessed in 601 women with PCOS and 168 brothers of affected women.

RESULTS

D19S884 allele 8 (A8) within intron 55 of the fibrillin-3 (FBN3) gene showed the strongest evidence for association with PCOS of 53 variants tested (P(corrected) = 0.0037). A8 was also associated with higher levels of fasting insulin and homeostasis model assessment for insulin resistance in women with PCOS and higher fasting levels of proinsulin and proinsulin/insulin ratio in brothers.

CONCLUSIONS

These findings strongly suggest that A8 of D19S884 is the chromosome 19p13.2 PCOS susceptibility locus. The association of D19S884 with markers of insulin resistance and pancreatic beta-cell dysfunction suggests that the same variant contributes to the reproductive and metabolic abnormalities of PCOS in affected women and their brothers.

Implication de l'interleukine 13 et de son récepteur dans la sclérodermie systémique

PURPOSE

Interleukin 13 is an immunoregulatory cytokine predominantly secreted by activated Th2 cells. It has similar functions with interleukin 4 and they share a common receptor. However, unlike interleukin 4, l'interleukin 13 does not appear to be important in the initial differentiation of CD4 T into Th2-type cells, but rather appears to be necessary in the effector phase of inflammation and fibrosis. This cytokine has been involved in recent works in allergic inflammation and in some fibrotic diseases leading to a scientific interest to analysis the role of interleukin 13 in systemic sclerosis (scleroderma).

MAIN POINTS

Systemic sclerosis is an autoimmune disease characterized by vascular alteration and skin and visceral fibrosis. A genetic background associated with susceptibility is supposed. Knowing the profibrogenic properties of interleukin 13, we asked if polymorphisms located in interleukin 13 and interleukin 13 receptor genes could be associated with systemic sclerosis. We observed significant associations between IL13 and IL13RA2 gene polymorphisms and the disease, particularly the cutaneous diffuse form of the disease.

PERSPECTIVES AND PROJECTS

Results concerning the involvement of interleukin 13 pathway in systemic sclerosis need to be confirmed on another larger population. Functional studies will be done to explain the effect of these associations. We feel that IL13/IL13R pathway is interesting as immunomodulation with the interleukin 13 receptor inhibitor is possible in therapy.

Scleroderma -- news to tell

Scleroderma is a chronic fibrosing disease, in which an early inflammatory reaction precedes the fibrotic response. Systematic analysis of the pathways involved in the development of the disease together with information derived from novel animal models have helped to better understand the mechanisms that trigger and sustain fibrotic reactions.

The genetics of the polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a very common endocrine disorder that has a strong genetic component and is characterized by polycystic ovaries, hyperandrogenemia, and menstrual irregularity. During the past decade, the roles of more than 70 candidate genes have been evaluated for a causal role in PCOS; however, because of genetic and phenotypic heterogeneity and underpowered studies, the results of many of these studies remain inconclusive. Here, the results of the genetic analysis of several candidate genes and gene regions-CYP11A (encoding cytochrome P450, family 11, subfamily A polypeptides), CAPN10 (encoding calpain 10), the insulin gene VNTR (variable number of tandem repeats), and D19S884 (a dinucleotide repeat marker mapping to chromosome 19p13.2)-are discussed in detail. Although past genetic studies of PCOS have yielded only modest results, resources and techniques have been assembled to remedy the major deficits of these early studies, promising that the next few years will be a very exciting and rewarding era for the genetic analysis of PCOS.

Update on pathophysiology of scleroderma with special reference to immunoinflammatory events

Scleroderma or systemic sclerosis (SSc) is a complex disease in which the vasculopathy and the activation of the immune system with production of inflammatory mediators lead to dysregulated fibroblast activation. The resulting excessive deposition of collagens and other extracellular matrix proteins ends in fibrosis and organ dysfunction. The cause is unknown, but environmental factors are thought to play a role by triggering abnormal responses in genetically susceptible hosts. The recent past has witnessed important advances in the definition of mechanisms that underlie the persistent activation in fibroblasts of genes involved in uncontrolled fibrosis, a hallmark of SSc. These include the preferential production of type 2 T cell cytokines in target organs, the presence of autoantibodies with fibroblast-activating capacities, the production of vasoconstrictive mediators that impact on fibroblast biosynthetic properties, the transforming growth factor-beta-related metabolic signature, and the presence of altered signaling pathways in fibroblasts. Furthermore, while no animal models recapitulate all the features of SSc, they have been instrumental for assessing the relevance of specific processes to the development of fibrosis. More importantly, some of the research findings are leading to therapies that target altered processes with the potential of changing the prognosis of some dismal aspects of the disease.

Facteurs de prédisposition génétiques à la fibrose au cours de la sclérodermie systémique

PURPOSE

Physiopathology of systemic sclerosis includes autoimmunity factors, endothelial lesions and abnormal fibrotic process which characterizes this disease in the field of systemic autoimmune disorders. Genetic factors of susceptibility are showed by possibility of familial forms of the disease, Choctaw American Indians homogenous population with high disease prevalence of systemic sclerosis and experimental animal models.

KEY POINTS

We propose a review of the articles published to date in the literature concerning genetical analysis of genes coding for factors potentially involved in the fibrotic process of systemic sclerosis. This includes cytokines (TNF-alpha, interleukin-1, chemokines), growth factors (TGF-beta), extracellular matrix proteins (collagen, fibrillin, fibronectine) and agents acting on vascular tone (angiotensin-converting enzyme and NO synthase).

PERSPECTIVES

Identification of genetic factors involved in the susceptibility to fibrosis of systemic sclerosis would lead to a better understanding of physiopathological mechanisms of this disease and to therapeutic targets using immunomodulation with drugs, such as already performed in rheumatoid arthritis.

Systemic sclerosis: current views of its pathogenesis

Systemic sclerosis (SSc) is an autoimmune disorder of unknown etiology characterized by severe and often progressive cutaneous and visceral fibrosis, pronounced alterations in the microvasculature, and numerous cellular and humoral immune abnormalities. Clinically, SSc is very heterogeneous, encompassing a spectrum ranging from mild limited forms of skin sclerosis with minimal internal organ involvement to severe skin and multiple internal organ fibrosis. Mortality and morbidity in SSc are very high and are directly related to the extent of the fibrotic and microvascular alterations. A better understanding of the pathogenesis of this incurable disorder will help to better target and design effective therapy in the future.

Systemic sclerosis: the susceptible host (genetics and environment)

It is becoming evident that several genetic factors participate in modulating susceptibility to SSc and its clinical manifestations. Some genes that specifically affect ECM metabolism and vascular function may be unique to SSc and scleroderma-related disorders; others, such as those genes involved in regulating immune tolerance, are likely shared with other autoimmune diseases. The effect of genetic variations (or polymorphisms) that are found in most of these genes taken individually will likely have only a small or modest effect on disease risk; only a few genetic variations are expected to be highly penetrant. Moreover, genetic studies in SSc have to deal with the additional issues of heterogeneous phenotypes, low disease prevalence in the general population, and an even greater paucity of multiplex families that makes traditional linkage studies difficult, if not impossible. Alternative approaches include allelic association studies, but conventional case-controls designs may be subject to selection bias and will require large sample sizes if the genes that are under investigation confer only modest (OR = 1.5-2.0) disease risk (Fig. 2). The simultaneous examination of several genes that are biologically relevant to a specific disease process to attain higher aggregate ORs, is one approach that was used in several reports that were cited in this review. The use of family-based controls, such as in the transmission-disequilibrium test (based on assessment of the transmitted or nontransmitted alleles that are associated with disease from heterozygous parents to affected offspring), would provide more robustness to spurious associations from population stratification, but is actually less powerful and efficient than case-control designs. Furthermore, for many late adult-onset diseases the effort required to obtain samples from living parents are for a variety of reasons not trivial. The success of these allelic association-based approaches depends on the identification of likely candidate disease genes (or at least markers in disequilibrium with disease genes), careful definition/ascertainment of disease phenotypes to minimize genetic heterogeneity, and for case-control designs, strategies to account for population stratification or admixture. The identification of candidate genes will be aided by rapid progress in the Human Genome Project and other genome efforts that will eventually identify all human genetic variations. Although this will lead to better understanding of the genes that might be involved in complex diseases, much work is required to understand the basic biology of how disease genotypes become clinical phenotypes. This is especially daunting in complex diseases, such as SSc, where the phenotype (including disease susceptibility and clinical presentation) is influenced by dynamic interactions between genetic variations and environment. Multi-center collaborative efforts with research paradigms that integrate genetic and environmental factors (including sociodemographic variables) will be required to elucidate the contribution of environment and genetics in the pathogenesis of SSc.

The genetics of systemic sclerosis

The etiopathogenesis of systemic sclerosis (SSc) is unclear. With no definitive evidence supporting an environmental cause, recent attention has focused on genetic factors. Familial clustering and ethnic influences have been demonstrated. Human leukocyte antigen (HLA) associations exist but are more related to the presence of particular autoantibodies rather than to the disease. In addition, no single major histocompatibility complex (MHC) allele predisposes to SSc in all ethnic groups. The role of microchimerism in SSc is a novel yet unproven hypothesis that may be related to intergenerational HLA compatibility. Recent studies investigating polymorphisms in genes coding for extracellular matrix proteins and cell-signaling molecules implicate non-MHC areas in SSc pathogenesis. The data reviewed suggest that SSc is a multigenic complex disorder.

Genetic epidemiology: systemic sclerosis

Systemic sclerosis (SSc) is a multisystem connective tissue disease characterised phenotypically by fibrosis and ischaemic atrophy. Its aetiology is most likely multifactorial. A genetic predisposition to the condition is suggested by reports of familial SSc (a positive family history is the strongest risk factor yet identified), by animal models, and by disease-association studies, in which researchers have examined a wide variety of genes including those involved in fibrosis, in vascular function and structure, and in autoimmunity - the relative rarity of SSc has precluded linkage studies, except in the Choctaw Indians. Recent advances in genetic methodologies should further our understanding of this complex disease process.