George N. Goulielmos

Association of a TRAF1 and a STAT4 gene polymorphism with increased risk for rheumatoid arthritis in a genetically homogeneous population.

Rheumatoid arthritis (RA) is a multifactorial disease that is increasing in incidence worldwide. It is associated with a complex mode of inheritance, with many genes being involved in the development and progression of the disease. Genome-wide association studies in different populations have recently revealed a significant association between a TRAF1/C5 and a STAT4 polymorphism and the development of RA. In the present study we performed a case-control study in the population of the island of Crete, Greece, aiming to replicate the former findings in a genetically homogeneous cohort of patients. We found that mutated allele A or genotypes A/A and G/A of the TRAF1/C5 rs10818488 SNP were more common in individuals with RA than in control individuals (odds ratio [OR]=1.7, 95% confidence interval [CI]=1.35-2.15, and OR=2.22, 95% CI=1.61-3.05, respectively). Similarly, mutated allele T or genotypes T/T and G/T of the STAT4 rs7574865 SNP were also associated with susceptibility to RA (OR=1.9, 95% CI=1.46-2.50, and OR=2.37, 95% CI 1.73-2.25, respectively). Thus, we conclude that mutant alleles or genotypes of both polymorphisms examined are associated with the development of RA in our population.

Investigation of potential non-HLA rheumatoid arthritis susceptibility loci in a European cohort increases the evidence for nine markers.

Background Genetic factors have a substantial role in determining development of rheumatoid arthritis (RA), and are likely to account for 50–60% of disease susceptibility. Genome-wide association studies have identified non-human leucocyte antigen RA susceptibility loci which associate with RA with low-to-moderate risk. Objectives To investigate recently identified RA susceptibility markers using cohorts from six European countries, and perform a meta-analysis including previously published results. Methods 3311 DNA samples were collected from patients from six countries (UK, Germany, France, Greece, Sweden and Denmark). Genotype data or DNA samples for 3709 controls were collected from four countries (not Sweden or Denmark). Eighteen single nucleotide polymorphisms (SNPs) were genotyped using Sequenom MassArray technology. Samples with a >95% success rate and only those SNPs with a genotype success rate of >95% were included in the analysis. Scandinavian patient data were pooled and previously published Swedish control data were accessed as a comparison group. Meta-analysis was used to combine results from this study with all previously published data. Results After quality control, 3209 patients and 3692 controls were included in the study. Eight markers (ie, rs1160542 (AFF3), rs1678542 (KIF5A), rs2476601 (PTPN22), rs3087243 (CTLA4), rs4810485 (CD40), rs5029937 (6q23), rs10760130 (TRAF1/C5) and rs7574865 (STAT4)) were significantly associated with RA by meta-analysis. All 18 markers were associated with RA when previously published studies were incorporated in the analysis. Data from this study increased the significance for association with RA and nine markers. Conclusions In a large European RA cohort further evidence for the association of 18 markers with RA development has been obtained.

Genetic, immunologic, and immunohistochemical analysis of the programmed death 1/programmed death ligand 1 pathway in human systemic lupus erythematosus

OBJECTIVE A putative regulatory intronic polymorphism (PD1.3) in the programmed death 1 (PD-1) gene, a negative regulator of T cells involved in peripheral tolerance, is associated with increased risk for systemic lupus erythematosus (SLE). We undertook this study to determine the expression and function of PD-1 in SLE patients. METHODS We genotyped 289 SLE patients and 256 matched healthy controls for PD1.3 by polymerase chain reaction-restriction fragment length polymorphism analysis. Expression of PD-1 and its ligand, PDL-1, was determined in peripheral blood lymphocytes and in renal biopsy samples by flow cytometry and immunohistochemistry. A crosslinker of PD-1 was used to assess its effects on anti-CD3/anti-CD28-induced T cell proliferation and cytokine production. RESULTS SLE patients had an increased frequency of the PD1.3 polymorphism (30.1%, versus 18.4% in controls; P=0.006), with the risk A allele conferring decreased transcriptional activity in transfected Jurkat cells. Patients homozygous for PD1.3-but not patients heterozygous for PD1.3-had reduced basal and induced PD-1 expression on activated CD4+ T cells. In autologous mixed lymphocyte reactions (AMLRs), SLE patients had defective PD-1 induction on activated CD4+ cells; abnormalities were more pronounced among homozygotes. PD-1 was detected within the glomeruli and renal tubules of lupus nephritis patients, while PDL-1 was expressed by the renal tubules of both patients and controls. PD-1 crosslinking suppressed proliferation and cytokine production in both normal and lupus T cells; addition of serum from patients with active SLE significantly ameliorated this effect on proliferation. CONCLUSION SLE patients display aberrant expression and function of PD-1 attributed to both direct and indirect effects. The expression of PD-1/PDL-1 in renal tissue and during AMLRs suggests an important role in regulating peripheral T cell tolerance.

Vitamin D receptor gene polymorphisms and susceptibility to type 1 diabetes in Crete, Greece

INTRODUCTION Association studies of vitamin D receptor (VDR) polymorphisms and risk of type 1 diabetes (T1D) have produced inconsistent results in different populations, pointing to contribution of additional genetic variants and environmental factors. In this study we investigated the association between four VDR polymorphisms and susceptibility to T1D in Crete, an island with homogenous population and considerably low incidence of T1D. RESULTS AND DISCUSSION We genotyped 100 patients with T1D and 96 controls for the FokI (rs10735810), BsmI (rs1544410), ApaI (rs7975232), and TaqI (rs731236) single nucleotide polymorphisms by polymerase chain reaction and restriction fragment length polymorphism analysis. In all 4 polymorphisms tested, distribution of VDR genotype frequencies differed significantly between patients and controls. Individuals with T1D presented less commonly with FokI F allele (p=0.008; OR 0.52, 95% CI 0.32 to 0.85) and BsmI B allele (p=0.042; OR 0.65, 95% CI 0.44 to 0.97) and more commonly with ApaI A allele (p=0.024; OR 1.61, 95% CI 1.07 to 2.41) and TaqI T allele (p=0.0001; OR 2.24, 95% CI 1.49 to 3.36). CONCLUSION Our findings derived from a homogenous southern European population with low incidence of T1D suggest that FokI, BsmI, ApaI, and TaqI polymorphisms of the VDR gene are associated with T1D prevalence.

Inflammasomes and rheumatic diseases: evolving concepts

The realisation that the production of inflammatory cytokines in inflammatory rheumatic diseases may be induced by non-infectious endogenous signals has encouraged researchers to explore mechanisms of innate immunity and their contribution to the pathogenesis of these diseases. The nucleotide-binding and oligomerisation domain (NOD)-like receptors (NLRs) sense pathogens, products of damaged cells or endogenous metabolites and could potentially be involved in the initiation, amplification and progression of the inflammatory response in rheumatic diseases. NLRs are involved in the regulation of innate immune responses with some of them promoting the activation of inflammatory caspases within multiprotein complexes, called inflammasomes. A typical inflammasome consists of a sensor, an NLR protein, an adaptor protein such as ASC (for apoptosis-associated speck-like protein containing a caspase recruitment domain (CARD)) and an effector protein that is a caspase that activates pro-inflammatory cytokines such as interleukin (IL)1β and IL18. Recent data suggest a role of the inflammasome in the pathogenesis of autoinflammatory as well as inflammatory rheumatic diseases such as juvenile chronic arthritis, adult onset Still disease, rheumatoid arthritis and gout. Modulation of these pathways may be a potential therapeutic target for inflammatory rheumatic diseases.

STAT4: A risk factor for type 1 diabetes?

Genes and mechanisms involved in autoimmune diseases, affecting approximately 5% of human population, remain still obscure but there is accumulating evidence that common genetic factors might predispose to multiple autoimmune disorders. STAT4, a transcription factor transmitting signals induced by several key cytokines, has recently been identified as a genetic risk factor for rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and Sjögrens disease (SD), thus indicating that multiple autoimmune diseases may share common biochemical pathways that lead to immune deregulation. Here we demonstrate for the first time, in a genetically homogeneous population, the association of the STAT4 rs7574865 G/T polymorphism, which has been shown to be associated with these autoimmune diseases, with susceptibility to type 1 diabetes (T1D). The susceptibility is associated with a significant increase of the frequency of the T allele (p = 0.0012, two-tailed chi(2), OR = 1.94, 95% CI = 1.29-2.91) in this single-nucleotide polymorphism (SNP). We also present an indication for association with Wegeners granulomatosis. These findings suggest that this variant form of STAT4 may have a putative key role in the development of a variety of autoimmune diseases, probably because of signaling defects that it causes in the IL-12 pathway.

The TRAF1-C5 region on chromosome 9q33 is associated with multiple autoimmune diseases.

Objectives The TRAF1-C5 locus has recently been identified as a genetic risk factor for rheumatoid arthritis (RA). Since genetic risk factors tend to overlap with several autoimmune diseases, a study was undertaken to investigate whether this region is associated with type 1 diabetes (TID), celiac disease (CD), systemic sclerosis (SSc) and systemic lupus erythematosus (SLE). Methods The most consistently associated SNP, rs10818488, was genotyped in a total of 735 patients with T1D, 1049 with CD, 367 with SSc, 746 with SLE and 3494 ethnically- and geographically-matched healthy individuals. The replication sample set consisted of 99 patients with T1D, 272 with SLE and 482 healthy individuals from Crete. Results A significant association was detected between the rs10818488 A allele and T1D (OR 1.14, p=0.027) and SLE (OR 1.16, p=0.016), which was replicated in 99 patients with T1D, 272 with SLE and 482 controls from Crete (OR 1.64, p=0.002; OR 1.43, p=0.002, respectively). Joint analysis of all patients with T1D (N=961) and all patients with SLE (N=1018) compared with 3976 healthy individuals yielded an allelic common OR of 1.19 (p=0.002) and 1.22 (p=2.6×10−4), respectively. However, combining our dataset with the T1D sample set from the WTCCC resulted in a non-significant association (OR 1.06, p=0.087). In contrast, previously unpublished results from the SLEGEN study showed a significant association of the same allele (OR 1.19, p=0.0038) with an overall effect of 1.22 (p=1.02×10−6) in a total of 1577 patients with SLE and 4215 healthy individuals. Conclusion A significant association was found for the TRAF1-C5 locus in SLE, implying that this region lies in a pathway relevant to multiple autoimmune diseases.

STAT4 gene polymorphism is associated with psoriasis in the genetically homogeneous population of Crete, Greece.

Recent genome-wide association studies (GWAS) of many complex diseases have successfully identified novel susceptibility loci, with many of them being associated with more than one condition. Taking into consideration that different autoimmune diseases may share some common pathogenetic pathways, we hypothesized that STAT4, a susceptibility gene found to be associated with increased risk for systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, Sjögrens syndrome, Wegeners granulomatosis, Crohns disease, and ulcerative colitis may also have a role in psoriasis. Psoriasis is an autoimmune, chronic inflammatory skin disease. Here we performed a case-control study in the population of island of Crete and demonstrated for the first time the association of a STAT4 single nucleotide polymorphism (SNP) with susceptibility to psoriasis, thus suggesting a putative key role of STAT4 in multiple autoimmune diseases. We found that mutated allele T of the STAT4 rs7574865 SNP, which previously was implicated in the predisposition to many autoimmune diseases, were more common in individuals with psoriasis than in controls (p = 0.045, odds ratio = 1.42, 95% confidence interval 1.01-2.00), thus concluding that the polymorphism examined is associated with the development of psoriasis in our population.

TRAF1/C5, eNOS, C1q, but not STAT4 and PTPN22 gene polymorphisms are associated with genetic susceptibility to systemic lupus erythematosus in Turkey

A significant source of variability in the literature on systemic lupus erythematosus (SLE) susceptibility genes has been the inability to replicate genetic findings across different racial or ethnic groups. We investigated whether a single nucleotide polymorphism (SNP) of the STAT4 (rs7574865), PTPN22 (rs2476601), TRAF1/C5 (rs10818488), and C1q (rs292001) genes as well as the 27-bp VNTR polymorphism on intron 4 of eNOS, previously associated with SLE in other populations, are also associated with SLE risk in Turkey. A group of 158 SLE patients and 155 healthy controls were included in this study. A genetic association of the TRAF1/C5, C1q, and eNOS gene polymorphism, but not of STAT4 and PTPN22, was found to confer a degree of risk for SLE. These data highlight the importance of comparative studies in different populations to confirm the previously detected genetic associations.

Gene expression analysis in RA: towards personalized medicine

Gene expression has recently been at the forefront of advance in personalized medicine, notably in the field of cancer and transplantation, providing a rational for a similar approach in rheumatoid arthritis (RA). RA is a prototypic inflammatory autoimmune disease with a poorly understood etiopathogenesis. Inflammation is the main feature of RA; however, many biological processes are involved at different stages of the disease. Gene expression signatures offer management tools to meet the current needs for personalization of RA patient’s care. This review analyses currently available information with respect to RA diagnostic, prognostic and prediction of response to therapy with a view to highlight the abundance of data, whose comparison is often inconclusive due to the mixed use of material source, experimental methodologies and analysis tools, reinforcing the need for harmonization if gene expression signatures are to become a useful clinical tool in personalized medicine for RA patients.