Association of osteopontin regulatory polymorphisms with systemic sclerosis

Neural repair function of osteopontin in stroke and stroke‑related diseases (Review)

Stroke, including hemorrhagic stroke and ischemic stroke, is a common disease of the central nervous system. It is characterized by a high mortality and disability rate and is closely associated with atherosclerosis, hypertension hyperglycemia, atrial fibrillation and unhealthy living habits. The continuous development of surgery and medications has decreased the mortality rate of patients with stroke and has greatly improved the disease prognosis. At present, the direction of clinical treatment and research has gradually shifted to the repair of nerve function after stroke. Osteopontin (OPN) is a widely distributed extracellular matrix protein. Due to its structural characteristics, OPN can be cut and modified into terminal fragments with different functions, which play different roles in various pathophysiological processes, such as formation of tumors, inflammation and autoimmune diseases. It has also become a potential diagnostic and therapeutic marker. In order to comprehensively analyze the specific role of OPN in nerve repair and its relationship with stroke and stroke-related diseases, the following key words were used: 'Osteopontin, stroke, atherosis, neuroplasticity, neural repair'. PubMed, Web of Science and Cochrane articles related to OPN were searched and summarized. The present review describes the OPN structure, isoforms, functions and its neural repair mechanism, and its association with the occurrence and development of stroke and related diseases was explored.

The critical role of osteopontin (OPN) in fibrotic diseases

Fibrosis is a pathological condition characterized by the excessive deposition of extracellular matrix components in tissues and organs, leading to progressive architectural remodelling and contributing to the development of various diseases. Osteopontin (OPN), a highly phosphorylated glycoprotein, has been increasingly recognized for its involvement in the progression of tissue fibrosis. This review provides a comprehensive overview of the genetic and protein structure of OPN and focuses on our current understanding of the role of OPN in the development of fibrosis in the lungs and other tissues. Additionally, special attention is given to the potential of OPN as a biomarker and a novel therapeutic target in the treatment of fibrosis.

Role of Osteopontin as a Potential Biomarker of Pulmonary Arterial Hypertension in Patients with Systemic Sclerosis and Other Connective Tissue Diseases (CTDs)

Pulmonary arterial hypertension (PAH) is a severe complication of connective tissue diseases (CTD). Its early diagnosis is essential to start effective treatment. In the present paper, we aimed to evaluate the role of plasma osteopontin (OPN) as a candidate biomarker of PAH in a cohort of CTD patients. OPN is a pleiotropic protein involved in inflammation and fibrogenesis and, therefore, potentially promising in this specific clinical context. We performed a cross-sectional observational study on a cohort of 113 CTD patients (females N = 101, 89.4%) affected by systemic sclerosis N = 88 (77.9%), mixed connective tissue disease N = 10 (8.8%), overlap syndrome N = 10 (8.8%) or undifferentiated connective tissue disease N = 5 (4.4%). CTD-PAH patients showed significantly higher OPN plasma values than patients with CTD alone (241.0 (188.8–387.2) vs. 200.7 (133.5–281.6) ng/mL; p = 0.03). Although OPN levels were directly correlated with age and inversely with glomerular filtration rate, they remained associated with PAH at multivariate analysis. In conclusion, OPN was significantly associated with PAH among patients with CTD, suggesting it may have a role as a non-invasive disease biomarker of PAH.

Emerging Roles of Matricellular Proteins in Systemic Sclerosis

Systemic sclerosis is a rare chronic heterogenous disease that involves inflammation and vasculopathy, and converges in end-stage development of multisystem tissue fibrosis. The loss of tight spatial distribution and temporal expression of proteins in the extracellular matrix (ECM) leads to progressive organ stiffening, which is a hallmark of fibrotic disease. A group of nonstructural matrix proteins, known as matricellular proteins (MCPs) are implicated in dysregulated processes that drive fibrosis such as ECM remodeling and various cellular behaviors. Accordingly, MCPs have been described in the context of fibrosis in sclerosis (SSc) as predictive disease biomarkers and regulators of ECM synthesis, with promising therapeutic potential. In this present review, an informative summary of major MCPs is presented highlighting their clear correlations to SSc- fibrosis.

Osteopontin at the Crossroads of Inflammation and Tumor Progression

Complex interactions between tumor and host cells regulate systemic tumor dissemination, a process that begins early at the primary tumor site and goes on until tumor cells detach themselves from the tumor mass and start migrating into the blood or lymphatic vessels. Metastatic cells colonize the target organs and are capable of surviving and growing at distant sites. In this context, osteopontin (OPN) appears to be a key determinant of the crosstalk between cancer cells and the host microenvironment, which in turn modulates immune evasion. OPN is overexpressed in several human carcinomas and has been implicated in inflammation, tumor progression, and metastasis. Thus, it represents one of the most attracting targets for cancer therapy. Within the tumor mass, OPN is secreted in various forms either by the tumor itself or by stroma cells, and it can exert either pro- or antitumorigenic effects according to the cell type and tumor microenvironment. Thus, targeting OPN for therapeutic purposes needs to take into account the heterogeneous functions of the multiple OPN forms with regard to cancer formation and progression. In this review, we will describe the role of systemic, tumor-derived, and stroma-derived OPN, highlighting its pivotal role at the crossroads of inflammation and tumor progression.

Association of Osteopontin Gene Polymorphisms with Colorectal Cancer

We investigated the association of the Osteopontin (OPN) (rs9138 and rs1126616) polymorphisms with colorectal cancer (CRC). One hundred CRC patients and 112 healthy individuals were subjected to OPN (rs9138 and rs1126616) genotyping and measurement of OPN protein plasma level. The C allele of OPN rs1126616 and the CC haplotype were significantly higher in CRC patient (p = 0.036, 0.003, respectively). In females, the C allele of OPN rs9318 (A/C) polymorphism was significantly associated with increased CRC risk (p = 0.036). The plasma OPN level >104.35 ng/mL was significantly associated with CRC. Our findings suggest a significant role played by OPN (rs9138 and rs1126616) in colorectal carcinogenesis.

Osteopontin Bridging Innate and Adaptive Immunity in Autoimmune Diseases

Osteopontin (OPN) regulates the immune response at multiple levels. Physiologically, it regulates the host response to infections by driving T helper (Th) polarization and acting on both innate and adaptive immunity; pathologically, it contributes to the development of immune-mediated and inflammatory diseases. In some cases, the mechanisms of these effects have been described, but many aspects of the OPN function remain elusive. This is in part ascribable to the fact that OPN is a complex molecule with several posttranslational modifications and it may act as either an immobilized protein of the extracellular matrix or a soluble cytokine or an intracytoplasmic molecule by binding to a wide variety of molecules including crystals of calcium phosphate, several cell surface receptors, and intracytoplasmic molecules. This review describes the OPN structure, isoforms, and functions and its role in regulating the crosstalk between innate and adaptive immunity in autoimmune diseases.

Genomic and genetic studies of systemic sclerosis: A systematic review

Systemic sclerosis is an autoimmune rheumatic disease characterised by fibrosis, vasculopathy and inflammation. The exact aetiology of SSc remains unknown but evidences show that various genetic factors may be involved. This review aimed to assess HLA alleles/non-HLA polymorphisms, microsatellites and chromosomal abnormalities that have thus far been associated with SSc. PubMed, Embase and Scopus databases were searched up to July 29, 2015 using a combination of search-terms. Articles retrieved were evaluated based on set exclusion and inclusion criteria. A total of 150 publications passed the filters. HLA and non-HLA studies showed that particular alleles in the HLA-DRB1, HLA-DQB1, HLA-DQA1, HLA-DPB1 genes and variants in STAT4, IRF5 and CD247 are frequently associated with SSc. Non-HLA genes analysis was performed using the PANTHER and STRING₁₀ databases. PANTHER classification revealed that inflammation mediated by chemokine and cytokine, interleukin and integrin signalling pathways are among the common extracted pathways associated with SSc. STRING₁₀ analysis showed that NFKB1, CSF3R, STAT4, IFNG, PRL and ILs are the main "hubs" of interaction network of the non-HLA genes associated with SSc. This study gathers data of valid genetic factors associated with SSc and discusses the possible interactions of implicated molecules.

Identification of an Association of TNFAIP3 Polymorphisms With Matrix Metalloproteinase Expression in Fibroblasts in an Integrative Study of Systemic Sclerosis-Associated Genetic and Environmental Factors

OBJECTIVE

Systemic sclerosis (SSc) is a fibrotic disease attributed to both genetic susceptibility and environmental factors. This study was undertaken to investigate the associations between SSc-associated genetic variants and the expression of extracellular matrix (ECM) genes in human fibroblasts stimulated with silica particles in time-course and dose-response experiments.

METHODS

A total of 200 fibroblast strains were examined for ECM gene expression after stimulation with silica particles. The fibroblasts were genetically profiled using Immunochip assays and then subjected to whole-genome genotype imputation. Associations of genotypes and gene expression were first analyzed in a Caucasian cohort and then validated in a meta-analysis combining the results from Caucasian, African American, and Hispanic subjects. A linear mixed model for longitudinal data analysis was used to identify genetic variants associated with the expression of ECM genes, and the associations were validated by using a haplotype-based longitudinal association test on regions that included the loci identified.

RESULTS

The single-nucleotide polymorphism rs58905141 in TNFAIP3 was consistently associated with time-course and/or dose-response expression of MMP3 and MMP1 in the fibroblasts stimulated with silica particles in both the analysis of Caucasian subjects only and the meta-analysis. Results of the haplotype-based analysis validated the association signals.

CONCLUSION

Our findings indicate that a genetic variant of TNFAIP3 is strongly associated with the silica-induced profibrotic response of fibroblasts. In silico functional analysis based on the ENCODE database revealed that rs58905141 might affect the binding activities of the transcription factors for TNFAIP3. This is the first genome-wide study of interactions between genetic and environmental factors in a complex SSc fibroblast model.

Association of SPP1 promoter variants with hip osteoarthritis susceptibility in Chinese population

Three genetic variants in the promoter of SPP1 (secreted phosphoprotein 1) gene have been reported to affect transcriptional activity of SPP1, thus conferring an increased risk for some diseases. To testify if these variants are associated with risk of hip osteoarthritis (OA) as well, we performed a case-control study including 389 hip OA patients and 315 healthy controls. Genotypes of SPP1 were determined by DNA sequencing, and differential expressions of SPP1 in relation with genotypes were evaluated by RT-PCR and ELISA. The results showed that rs17524488 (delG>insG) increased the risk of hip OA, with the adjusted OR 1.48 (95% CI 1.18-1.85, P<0.01) for risk allele insG, 1.90 (95% CI 1.35-2.66, P<0.01) for delG/insG and 2.04 (95% CI 1.20-3.49, P<0.01) for insG/insG respectively. However, as for rs11730582 (T>C), the adjusted ORs were 1.18 (95% CI 0.94-1.49, P=0.148) for allele C, 1.26 (95% CI 0.90-1.75, P=0.158) for TC, and 1.31 (95% CI 0.77-2.24, P=0.293) for CC, indicating no association of rs11730582 with hip OA risk. The variant rs28357094 was not observed in the tested subjects. Furthermore, the delG/insG and insG/insG genotypes of rs17524488 both correlated with higher levels of SPP1 expression in articular cartilage (P<0.01 for all comparisons) as well as in in synovial fluid (P<0.01 for all comparisons) compared with delG/delG, while rs11730582 had no effect on the SPP1 expression (P>0.05 for all comparisons). These results collectively indicate that the genetic variant rs17524488 in SPP1 promoter confers high risk for hip OA in a Chinese population, possibly through enhancing SPP1 expression.

Emerging clinical phenotypes associated with anti-cytokine autoantibodies

Anti-cytokine autoantibodies (AAbs) are frequent and involve a very large panel of cytokines both in healthy subjects and in patients with various pathological conditions. In healthy individuals, anti-cytokine AAbs are described as a part of the natural AAb repertoire and are thought to contribute to the fine regulation of cytokine homeostasis. In some patients, neutralizing AAbs targeting cytokines required for the immune protection against specific microbes may induce acquired immunodeficiency leading to very specific infectious phenotypes. For instance, anti-IFNγ AAbs may induce disseminated non-tuberculous mycobacterial infections; anti-IL-17 AAbs are associated with the development of chronic mucosal candidiasis, and anti-IL-6 AAbs with severe staphylococcal or streptococcal infections. In patients with autoimmune diseases, AAbs directed against pathogenic cytokines are able to influence the course of the diseases. In lupus patients, neutralizing anti-IFNα and anti-TNFα AAbs are associated with a decreased bioactivity of the corresponding cytokine and a lower disease severity. Similarly, anti-IL-1α AAbs are associated with nondestructive forms of chronic polyarthritis. More surprisingly, neutralizing anti-BAFF AAbs are observed in the serum of lupus patients with elevated IFNα signature and higher disease activity. In this review, we summarize the current literature describing the different phenotypes and the main mechanisms associated with the occurrence of anti-cytokine AAbs.

Secreted phosphoprotein 1 is a determinant of lung function development in mice

Secreted phosphoprotein 1 (Spp1) is located within quantitative trait loci associated with lung function that was previously identified by contrasting C3H/HeJ and JF1/Msf mouse strains that have extremely divergent lung function. JF1/Msf mice with diminished lung function had reduced lung SPP1 transcript and protein during the peak stage of alveologenesis (postnatal day [P]14-P28) as compared with C3H/HeJ mice. In addition to a previously identified genetic variant that altered runt-related transcription factor 2 (RUNX2) binding in the Spp1 promoter, we identified another promoter variant in a putative RUNX2 binding site that increased the DNA protein binding. SPP1 induced dose-dependent mouse lung epithelial-15 cell proliferation. Spp1((-/-)) mice have decreased specific total lung capacity/body weight, higher specific compliance, and increased mean airspace chord length (Lm) compared with Spp1((+/+)) mice. Microarray analysis revealed enriched gene ontogeny categories, with numerous genes associated with lung development and/or respiratory disease. Insulin-like growth factor 1, Hedgehog-interacting protein, wingless-related mouse mammary tumor virus integration site 5A, and NOTCH1 transcripts decreased in the lung of P14 Spp1((-/-)) mice as determined by quantitative RT-PCR analysis. SPP1 promotes pneumocyte growth, and mice lacking SPP1 have smaller, more compliant lungs with enlarged airspace (i.e., increased Lm). Microarray analysis suggests a dysregulation of key lung developmental transcripts in gene-targeted Spp1((-/-)) mice, particularly during the peak phase of alveologenesis. In addition to its known roles in lung disease, this study supports SPP1 as a determinant of lung development in mice.

Systemic Sclerosis is a Complex Disease Associated Mainly with Immune Regulatory and Inflammatory Genes

Systemic sclerosis (SSc) is a fibrotic and autoimmune disease characterized clinically by skin and internal organ fibrosis and vascular damage, and serologically by the presence of circulating autoantibodies. Although etiopathogenesis is not yet well understood, the results of numerous genetic association studies support genetic contributions as an important factor to SSc. In this paper, the major genes of SSc are reviewed. The most recent genome-wide association studies (GWAS) are taken into account along with robust candidate gene studies. The literature search was performed on genetic association studies of SSc in PubMed between January 2000 and March 2014 while eligible studies generally had over 600 total participants with replication. A few genetic association studies with related functional changes in SSc patients were also included. A total of forty seven genes or specific genetic regions were reported to be associated with SSc, although some are controversial. These genes include HLA genes, STAT4, CD247, TBX21, PTPN22, TNFSF4, IL23R, IL2RA, IL-21, SCHIP1/IL12A, CD226, BANK1, C8orf13-BLK, PLD4, TLR-2, NLRP1, ATG5, IRF5, IRF8, TNFAIP3, IRAK1, NFKB1, TNIP1, FAS, MIF, HGF, OPN, IL-6, CXCL8, CCR6, CTGF, ITGAM, CAV1, MECP2, SOX5, JAZF1, DNASEIL3, XRCC1, XRCC4, PXK, CSK, GRB10, NOTCH4, RHOB, KIAA0319, PSD3 and PSOR1C1. These genes encode proteins mainly involved in immune regulation and inflammation, and some of them function in transcription, kinase activity, DNA cleavage and repair. The discovery of various SSc-associated genes is important in understanding the genetics of SSc and potential pathogenesis that contribute to the development of this disease.

Current status of systemic sclerosis biomarkers: applications for diagnosis, management and drug development

Systemic sclerosis (SSc) is a clinically heterogeneous orphan disease of unknown etiology and no effective therapy. It is characterized by protean manifestations, an unpredictable disease course and variable outcomes. Clinical manifestations reflect underlying autoimmunity, small vessel vasculopathy and progressive multi-organ fibrosis. Predicting disease progression, pattern and severity of complications and response to therapy in SSc remain major challenges both for the management of patients and for the development of effective disease-modifying therapies. This review summarizes contemporary understanding of novel and emerging biomarkers for SSc. We focus on the development of new classification criteria, the utility of SSc-specific autoantibodies as diagnostic and prognostic markers, and on biomarkers for skin and lung involvement. Finally, we review genome-wide expression analysis as a tool to predict therapeutic responses. We anticipate that the development, validation and application of these biomarkers, singly or more likely in combination, will have a transformative impact in SSc, informing early diagnosis, classification and management, as well as the design, execution and interpretation of clinical trials of novel therapeutic agents.

Is osteopontin involved in cutaneous fibroblast activation? Its hypothetical role in scleroderma pathogenesis

Osteopontin (OPN) is an extracellular matrix protein implicated in bone remodeling, but it presents also pro-inflammatory and pro-fibrotic properties. OPN expression also occurs upon exposure of cells to classical mediators of acute inflammation such as tumor necrosis growth factor alpha (TNF-alpha) and interleukin-1 beta (IL-1beta), as well as fibrogenic cytokines such as transforming growth factor beta (TGF-beta), although a detailed understanding of these regulatory pathways is still unknown. Plasma OPN levels in both limited and diffuse systemic sclerosis patients (lSSc and dSSc) were statistically higher compared to those of control subjects. Immunohistology demonstrated that high TGF-beta levels, alpha smooth muscle actin (alphaSMA) levels and consequently high OPN levels were found in the affected skin of sclerodermic patients (lSSc and dSSc) compared to levels found in healthy skin. In order to better understand how OPN interferes with the fibrotic process, healthy skin fibroblasts were treated for 24 and 48 hours with bleomycin and with endothelin-1 (ET-1) plus TGF-beta in order to induce the fibrogenesis. After 48 hours of stimulation, healthy treated fibroblasts showed statistically increased alphaSMA levels (index of differentiation into myofibroblasts) and simultaneously statistically increased OPN levels compared to healthy untreated ones. This study demonstrates that OPN levels increase simultaneously with the increasing of alphaSMA levels, therefore it is reasonable to hypothesize that OPN interferes in the pathogenesis of Systemic Sclerosis in the early stage of fibroblast differentiation process.

Identification of secreted phosphoprotein 1 gene as a new rheumatoid arthritis susceptibility gene

OBJECTIVE

To evaluate the contribution of the SPP1 rs11439060 and rs9138 polymorphisms, previously reported as autoimmune risk variants, in the rheumatoid arthritis (RA) genetic background according to anti-citrullinated protein antibodies (ACPAs) status of RA individuals.

METHODS

We analysed a total of 11,715 RA cases and 26,493 controls from nine independent cohorts; all individuals were genotyped or had imputed genotypes for SPP1 rs11439060 and rs9138. The effect of the SPP1 rs11439060 and rs9138 risk-allele combination on osteopontin (OPN) expression in macrophages and OPN serum levels was investigated.

RESULTS

We provide evidence for a distinct contribution of SPP1 to RA susceptibility according to ACPA status: the combination of ≥3 SPP1 rs11439060 and rs9138 common alleles was associated mainly with ACPA negativity (p=1.29×10(-5), ORACPA-negative 1.257 (1.135 to 1.394)) and less with ACPA positivity (p=0.0148, ORACPA-positive 1.072 (1.014 to 1.134)). The ORs between these subgroups (ie, ACPA-positive and ACPA-negative) significantly differed (p=7.33×10(-3)). Expression quantitative trait locus analysis revealed an association of the SPP1 risk-allele combination with decreased SPP1 expression in peripheral macrophages from 599 individuals. To corroborate these findings, we found an association of the SPP1 risk-allele combination and low serum level of secreted OPN (p=0.0157), as well as serum level of secreted OPN correlated positively with ACPA production (p=0.005; r=0.483).

CONCLUSIONS

We demonstrate a significant contribution of the combination of SPP1 rs11439060 and rs9138 frequent alleles to risk of RA, the magnitude of the association being greater in patients negative for ACPAs.

Novel investigational agents for the treatment of scleroderma

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

The polymorphisms of osteopontin gene and plasma osteopontin protein levels with susceptibility to colorectal carcinoma

Osteopontin (OPN) plays an important role in the development and progression of some tumors. The polymorphisms of OPN probably change its expression and contribute to interindividual differences of susceptibility to some cancers. The purpose of the present study was to explore the association of rs9138 (+1239; 3'UTR: 3'untranslated regions) and rs1126616 (+750; exon 7) polymorphisms located in the OPN gene with colorectal carcinoma (CRC) susceptibility and to investigate the correlation of the polymorphisms, plasma levels of the OPN protein, clinicopathologic parameters, tumor markers, and lipid. The genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. The plasma levels, tumor markers, and lipid were measured by enzyme-linked immunosorbent assay. The results indicated that genotype AA and AC of rs9138 and CC and CT of rs1126616 were associated with increased risk of CRC. The allelic frequencies of rs9138A, rs1126616C, and the haplotype (A-C) were associated with increased risk of CRC. Although there was no significant difference of plasma levels in various genotypes, increased plasma protein expression in CRC patients compared with controls was found. Our results suggested that the rs9138 and rs1126616 of OPN were associated with CRC risk, and the OPN protein in plasma may be a potential tumor marker of CRC.

An osteopontin promoter polymorphism is associated with aggressiveness in breast cancer

Metastasis-related genes are deregulated in cancer by aberrant expression or splicing. Here, we analyzed polymorphic sites in the osteopontin promoter as potential contributors to aberrant expression in breast cancers. This study comprised 241 breast cancer specimens, for which DNA from normal surrounding tissue was available for 111, and 65 healthy breast samples. The polymorphic site in position -443 of the promoter was associated with tumor grade. As expected, there was no association between promoter single nucleotide polymorphisms (SNPs) and tumor stage or in situ carcinoma versus cancer, as stage and early transformation are determined by the sampling time more than by tumor genetics. In a subset of samples, osteopontin RNA expression levels had previously been obtained. The allelic distribution in positions -443 and -1748 was distinct between high and low expressors, confirming the importance of promoter SNPs. These two sites also form a haplotype. Osteopontin expression has been associated with breast cancer progression, regardless of the histological subtype of the cancer. Remarkably, the polymorphic site at -443, but not -1748 or -1776, showed differences between ER-positive and ER-negative breast cancers and between PR-positive and PR-negative breast cancers, but there was no association with HER2 status. In five cases, the genotype of the tumor was different from the genotype of the host, implying the possibility of somatic mutations in the osteopontin promoter that may affect expression. Our results corroborate that the osteopontin promoter SNPs -443 (rs11730582) and -1748 (rs2728127) are important for gene expression and breast cancer aggressiveness.

Osteopontin promoter polymorphisms are associated with susceptibility to gastric cancer

GOALS

To evaluate the significance of osteopontin (OPN) genotypes in the susceptibility to gastric cancer.

BACKGROUND

The expression of OPN has been correlated with development, invasiveness, metastasis, and survival of gastric cancer, but the role of polymorphisms in the OPN promoter has not been investigated.

STUDY

We enrolled 146 gastric cancer patients and 128 controls. DNA was extracted from peripheral blood leucocytes. Single-nucleotide polymorphisms (SNPs) in the OPN promoter (-66, -156, -443, -616, -1748, and -1776) were analyzed by pyrosequencing and direct sequencing methods. Logistic regression analyses were used to evaluate the associations between SNPs and development of gastric cancer.

RESULTS

SNP -443 C/C and -616 T/T of the OPN promoter were significantly associated with gastric cancer [odds ratio (OR)=2.88; 95% confidence interval (CI), 1.16-7.12 and OR=1.95; 95% CI, 1.35-2.82, respectively]. Analysis of the combined effect of OPN promoter SNPs revealed that the combination of SNP -443 (T/C or C/C) and SNP -616 (T/T or T/G) had the most significant association with gastric cancer (OR=3.95; 95% CI, 1.58-9.90).

CONCLUSIONS

Our results suggest that polymorphisms in the OPN promoter are associated with the development of gastric cancer, and the combination of SNP -443 (T/C or C/C) and -616 (T/T or T/G) most significantly increases susceptibility to gastric cancer.

Variations of the UNC13D gene in patients with autoimmune lymphoproliferative syndrome

Autoimmune lymphoproliferative syndrome (ALPS) is caused by genetic defects decreasing Fas function and is characterized by lymphadenopathy/splenomegaly and expansion of CD4/CD8 double-negative T cells. This latter expansion is absent in the ALPS variant named Dianzani Autoimmune/lymphoproliferative Disease (DALD). In addition to the causative mutations, the genetic background influences ALPS and DALD development. We previously suggested a disease-modifying role for the perforin gene involved in familial hemophagocytic lymphohistiocytosis (FHL). The UNC13D gene codes for Munc13-4, which is involved in perforin secretion and FHL development, and thus, another candidate for a disease-modifying role in ALPS and DALD. In this work, we sequenced UNC13D in 21 ALPS and 20 DALD patients and compared these results with sequences obtained from 61 healthy subjects and 38 multiple sclerosis (MS) patients. We detected four rare missense variations in three heterozygous ALPS patients carrying p.Cys112Ser, p.Val781Ile, and a haplotype comprising both p.Ile848Leu and p.Ala995Pro. Transfection of the mutant cDNAs into HMC-1 cells showed that they decreased granule exocytosis, compared to the wild-type construct. An additional rare missense variation, p.Pro271Ser, was detected in a healthy subject, but this variation did not decrease Munc13-4 function. These data suggest that rare loss-of-function variations of UND13D are risk factors for ALPS development.

Systemic sclerosis: genetics and epigenetics

Systemic sclerosis (SSc) is an autoimmune disease characterized by immune abnormalities, vascular obliteration, excessive extracellular matrix deposition, and fibrosis of the skin and/or internal organs. To date, the exact etiology of this complicated disease remains unknown. Over the past few years, however, the role of genetic susceptibility and epigenetic modifications caused by environmental factors have been intensively studied in relation to the pathogenesis of this disease, and important advances have been made. This review focuses on the recent progress in the field of SSc research, including HLA and non-HLA susceptibility genes identified in genome-wide association studies (GWAS), and aberrant epigenetic modifications of gene loci associated with SSc. HLA genes most closely linked with SSc susceptibility include HLA-A, -B, -C, -DR, -DP and -DQ. A large number of non-HLA genes were also reported. It has also been noted that different genetic variants can be linked to specific clinical patterns. Finally, DNA demethylation of regulatory genes (eNOS, CD40L and CD70), therapeutic effects associated with Trichostatin A (TSA) treatment, and abnormal expression of a large spectrum of microRNAs (miR-21, -31, -146, -503, -145, -29b, etc.) are all observed in SSc. Overall, the findings presented in this review illustrate how both genetic and epigenetic aberrations play important roles in the development of SSc; however, several unanswered questions continue to impede our understanding of this complex disease. Future research should focus on the identification of new biomarkers for early diagnosis and prognosis, which will help improve the clinical outcome of patients with SSc.

The impact of osteopontin gene variations on multiple sclerosis development and progression

Osteopontin is a proinflammatory molecule, modulating TH1 and TH17 responses. Several reports suggest its involvement in multiple sclerosis (MS) pathogenesis. We previously reported that OPN gene variations at the 3' end are a predisposing factor for MS development and evolution. In this paper, we extended our analysis to a gene variation at the 5' end on the -156G > GG single nucleotide polymorphism (SNP) and replicated our previous findings at the 3' end on the +1239A > C SNP. We found that only +1239A > C SNP displayed a statistically significant association with MS development, but both +1239A > C and -156G > GG had an influence on MS progression, since patients homozygous for both +1239A and -156GG alleles displayed slower progression of disability and slower switch to secondary progression than those carrying +1239C and/or -156G and those homozygous for +1239A only. Moreover, patients homozygous for +1239A also displayed a significantly lower relapse rate than those carrying +1239C, which is in line with the established role of OPN in MS relapses.

Hepatocyte growth factor increases osteopontin expression in human osteoblasts through PI3K, Akt, c-Src, and AP-1 signaling pathway

Background

Hepatocyte growth factor (HGF) has been demonstrated to stimulate osteoblast proliferation and participated bone remodeling. Osteopontin (OPN) is a secreted phosphoglycoprotein that belongs to the SIBLING family and is present during bone mineralization. However, the effects of HGF on OPN expression in human osteoblasts are large unknown.

Methodology/Principal Findings

Here we found that HGF induced OPN expression in human osteoblasts dose-dependently. HGF-mediated OPN production was attenuated by c-Met inhibitor and siRNA. Pretreatment of osteoblasts with PI3K inhibitor (Ly294002), Akt inhibitor, c-Src inhibitor (PP2), or AP-1 inhibitor (curcumin) blocked the potentiating action of HGF. Stimulation of osteoblasts with HGF enhanced PI3K, Akt, and c-Src activation. In addition, incubation of cells with HGF also increased c-Jun phosphorylation, AP-1-luciferase activity, and c-Jun binding to the AP-1 element on the OPN promoter. HGF-mediated AP-1-luciferase activity and c-Jun binding to the AP-1 element was reduced by c-Met inhibitor, Ly294002, Akt inhibitor, and PP2.

Conclusions/Significance

Our results suggest that the interaction between HGF and c-Met increases OPN expression in human osteoblasts via the PI3K, Akt, c-Src, c-Jun, and AP-1 signaling pathway.

The role of osteopontin (OPN/SPP1) haplotypes in the susceptibility to Crohn's disease

BACKGROUND

Osteopontin represents a multifunctional molecule playing a pivotal role in chronic inflammatory and autoimmune diseases. Its expression is increased in inflammatory bowel disease (IBD). The aim of our study was to analyze the association of osteopontin (OPN/SPP1) gene variants in a large cohort of IBD patients.

METHODOLOGY/PRINCIPAL FINDINGS

Genomic DNA from 2819 Caucasian individuals (n = 841 patients with Crohn's disease (CD), n = 473 patients with ulcerative colitis (UC), and n = 1505 healthy unrelated controls) was analyzed for nine OPN SNPs (rs2728127, rs2853744, rs11730582, rs11739060, rs28357094, rs4754 = p.Asp80Asp, rs1126616 = p.Ala236Ala, rs1126772 and rs9138). Considering the important role of osteopontin in Th17-mediated diseases, we performed analysis for epistasis with IBD-associated IL23R variants and analyzed serum levels of the Th17 cytokine IL-22. For four OPN SNPs (rs4754, rs1126616, rs1126772 and rs9138), we observed significantly different distributions between male and female CD patients. rs4754 was protective in male CD patients (p = 0.0004, OR = 0.69). None of the other investigated OPN SNPs was associated with CD or UC susceptibility. However, several OPN haplotypes showed significant associations with CD susceptibility. The strongest association was found for a haplotype consisting of the 8 OPN SNPs rs2728127-rs2853744-rs11730582-rs11439060-rs28357094-rs112661-rs1126772-rs9138 (omnibus p-value = 2.07×10⁻⁸). Overall, the mean IL-22 secretion in the combined group of OPN minor allele carriers with CD was significantly lower than that of CD patients with OPN wildtype alleles (p = 3.66×10⁻⁵). There was evidence for weak epistasis between the OPN SNP rs28357094 with the IL23R SNP rs10489629 (p = 4.18×10⁻²) and between OPN SNP rs1126616 and IL23R SNP rs2201841 (p = 4.18×10⁻²) but none of these associations remained significant after Bonferroni correction.

CONCLUSIONS/SIGNIFICANCE

Our study identified OPN haplotypes as modifiers of CD susceptibility, while the combined effects of certain OPN variants may modulate IL-22 secretion.