Interferon regulatory factor 5 gene variants rs2004640 and rs4728142 are associated with carotid intima media thickness but not with cardiovascular events in rheumatoid arthritis

OBJECTIVES

Rheumatoid arthritis (RA) is associated with cardiovascular (CV) morbidity and mortality. Interferon regulatory factor 5 (IRF5) gene polymorphisms rs2004640 and rs4728142 have been associated with autoimmune diseases, but also with atherosclerosis. Differences in IRF5 gene expression can lead to the production of different interferons and might play a role in the atherogenic process in RA.

METHODS

We investigated the effects of IRF5 gene variants rs2004640 and rs4728142 on clinical parameters related to atherosclerosis, such as cIMT (in subgroup n=101), and new CV events (in whole cohort n=353).

RESULTS

For rs2004640, cIMT values at baseline were highest within the group of patients carrying the GG-genotype, followed by GT- and TT- genotypes, which was statistically significant. Over time patients with the TT-genotype had the highest increase in cIMT. For rs4728142 cIMT values were also the highest for patients with the GG-genotype at baseline, but the difference between the groups was not statistically significant. Over time the highest increase in cIMT was in the patients with the AA-genotype. Both rs2004640 and rs4728142 were not associated with new CV events during follow-up.

CONCLUSIONS

IRF5 alleles are associated with changes in cIMT, but not with new CV events in RA. Although these findings implicate a role of the IRF5 transcription pathway in atherosclerosis, IRF5 single nucleotide polymorphisms do not appear to increase the risk of future CV events.

Carrier Detection in Severe (Type III) von Willebrand Disease Using Two Intragenic Restriction Fragment Length Polymorphisms

DNA from a family with a female member affected with severe (type III) vWD was analysed using three restriction enzymes and a partial vWF cDNA probe. Two restriction fragment length polymorphisms (RFLPs) detected with the enzymes Bgl II and Xba I proved to be informative in this family. A 36.0 Kb allele, demonstrated with the enzyme Xba I was rare in the general population but very important in this family for segregation analysis of the alleles and their association with the putative defective chromosome. The propositus was homozygous for the 36.0 Kb Xba I polymorphic band and heterozygous for the Bgl II polymorphism. She was the only member of the family showing this allelic pattern. The linkage of the alleles could be determined because her mother was homozygous for the 9.0 Kb Bgl II polymorphism but heterozygous for the Xba I polymorphism. The segregation of the alleles could be traced to the proband’s son and a niece. The genotypic analysis revealed that her niece could be considered as carrying a defective gene for severe vWD.

Autoantibody Specificities and Type I Interferon Pathway Activation in Idiopathic Inflammatory Myopathies

Myositis is a heterogeneous group of autoimmune diseases, with different pathogenic mechanisms contributing to the different subsets of disease. The aim of this study was to test whether the autoantibody profile in patients with myositis is associated with a type I interferon (IFN) signature, as in patients with systemic lupus erythematous (SLE). Patients with myositis were prospectively enrolled in the study and compared to healthy controls and to patients with SLE. Autoantibody status was analysed using an immunoassay system and immunoprecipitation. Type I IFN activity in whole blood was determined using direct gene expression analysis. Serum IFN-inducing activity was tested using peripheral blood cells from healthy donors. Blocking experiments were performed by neutralizing anti-IFNAR or anti-IFN-α antibodies. Patients were categorized into IFN high and IFN low based on an IFN score. Patients with autoantibodies against RNA-binding proteins had a higher IFN score compared to patients without these antibodies, and the IFN score was related to autoantibody multispecificity. Patients with dermatomyositis (DM) and inclusion body myositis (IBM) had a higher IFN score compared to the other subgroups. Serum type I IFN bioactivity was blocked by neutralizing anti-IFNAR or anti-IFN-α antibodies. To conclude, a high IFN score was not only associated with DM, as previously reported, and IBM, but also with autoantibody monospecificity against several RNA-binding proteins and with autoantibody multispecificity. These studies identify IFN-α in sera as a trigger for activation of the type I IFN pathway in peripheral blood and support IFN-α as a possible target for therapy in these patients.

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 patients' 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.

Sex differences in the human peripheral blood transcriptome

BACKGROUND

Genomes of men and women differ in only a limited number of genes located on the sex chromosomes, whereas the transcriptome is far more sex-specific. Identification of sex-biased gene expression will contribute to understanding the molecular basis of sex-differences in complex traits and common diseases.

RESULTS

Sex differences in the human peripheral blood transcriptome were characterized using microarrays in 5,241 subjects, accounting for menopause status and hormonal contraceptive use. Sex-specific expression was observed for 582 autosomal genes, of which 57.7% was upregulated in women (female-biased genes). Female-biased genes were enriched for several immune system GO categories, genes linked to rheumatoid arthritis (16%) and genes regulated by estrogen (18%). Male-biased genes were enriched for genes linked to renal cancer (9%). Sex-differences in gene expression were smaller in postmenopausal women, larger in women using hormonal contraceptives and not caused by sex-specific eQTLs, confirming the role of estrogen in regulating sex-biased genes.

CONCLUSIONS

This study indicates that sex-bias in gene expression is extensive and may underlie sex-differences in the prevalence of common diseases.

Using biomarkers to predict progression from clinically isolated syndrome to multiple sclerosis

Background

Detection of brain lesions disseminated in space and time by magnetic resonance imaging remains a cornerstone for the diagnosis of clinically definite multiple sclerosis. We have sought to determine if gene expression biomarkers could contribute to the clinical diagnosis of multiple sclerosis.

Methods

We employed expression levels of 30 genes in blood from 199 subjects with multiple sclerosis, 203 subjects with other neurologic disorders, and 114 healthy control subjects to train ratioscore and support vector machine algorithms. Blood samples were obtained from 46 subjects coincident with clinically isolated syndrome who progressed to clinically definite multiple sclerosis determined by conventional methods. Gene expression levels from these subjects were inputted into ratioscore and support vector machine algorithms to determine if these methods also predicted that these subjects would develop multiple sclerosis. Standard calculations of sensitivity and specificity were employed to determine accuracy of these predictions.

Results

Our results demonstrate that ratioscore and support vector machine methods employing input gene transcript levels in blood can accurately identify subjects with clinically isolated syndrome that will progress to multiple sclerosis.

Conclusions

We conclude these approaches may be useful to predict progression from clinically isolated syndrome to multiple sclerosis.

Gene-expression signatures: biomarkers toward diagnosing multiple sclerosis

Identification of biomarkers contributing to disease diagnosis, classification or prognosis could be of considerable utility. For example, primary methods to diagnose multiple sclerosis (MS) include magnetic resonance imaging and detection of immunological abnormalities in cerebrospinal fluid. We determined whether gene-expression differences in blood discriminated MS subjects from comparator groups, and identified panels of ratios that performed with varying degrees of accuracy depending upon complexity of comparator groups. High levels of overall accuracy were achieved by comparing MS with homogeneous comparator groups. Overall accuracy was compromised when MS was compared with a heterogeneous comparator group. Results, validated in independent cohorts, indicate that gene-expression differences in blood accurately exclude or include a diagnosis of MS and suggest that these approaches may provide clinically useful prediction of MS.

Biomarkers and personalised medicine in rheumatoid arthritis: a proposal for interactions between academia, industry and regulatory bodies

Rheumatoid arthritis (RA) is one of the most appropriate conditions for the application of personalised medicine as a high degree of heterogeneity has been recognised, which remains to be explained. Such heterogeneity is also reflected in the large number of treatment targets and options. A growing number of biologics as well as small molecules are already in use and there are promising new drugs in development. In order to make the best use of treatment options, both targeted and non-targeted biomarkers have to be identified and validated. To this aim, new rules are needed for the interaction between academia and industry under regulatory control. Setting up multi-centre biosample collections with clear definition of access, organising early, possibly non-committing discussions with regulatory authorities, and defining a clear route for the validation, qualification and registration of the biomarker-drug combination are some of the more critical areas where effective collaboration between the drug industry, academia and regulators is needed.

Interferon regulatory factor 5 gene variants and pharmacological and clinical outcome of Interferonβ therapy in multiple sclerosis

Interferon-β (IFNβ) therapy is effective in approximately half of the patients with relapsing-remitting multiple sclerosis (RRMS). Clinical non-responders were characterized by an increased expression of IFN response genes before the start of therapy, and a lack of a pharmacologically induced increase in IFN response gene activity. Because Interferon Regulatory Factor 5 (IRF5) is a master regulator of IFN-activity, we carried out a candidate gene study of IRF5 gene variants in relation to the pharmacological and clinical response upon IFNβ treatment. We found that patients with the IRF5 rs2004640-TT and rs47281420-AA genotype exerted a poor pharmacological response to IFNβ compared with patients carrying the respective G-alleles (P=0.0006 and P=0.0023, respectively). Moreover, patients with the rs2004640-TT genotype developed more magnetic resonance imaging (MRI)-based T2 lesions during IFNβ treatment (P=0.003). Accordingly, an association between MRI-based non-responder status and rs2004640-TT genotype was observed (P=0.010). For the rs4728142-AA genotype a trend of an association with more T2 lesions during IFNβ treatment and MRI-based non-responder status was observed (P=0.103 and P=0.154, respectively). The clinical relevance of the rs2004640-TT genotype was validated in an independent cohort wherein a shorter time to first relapse was found (P=0.037). These findings suggest a role for IRF5 gene variation in the pharmacological and clinical outcome of IFNβ therapy that might have relevance as biomarker to predict the response to IFNβ in multiple sclerosis.

Transcript profiling towards personalised medicine in rheumatoid arthritis

Rheumatoid arthritis (RA ) is a chronic inflammatory joint disease that is heterogeneous in nature. The heterogeneity is reflected by the variation in responsiveness to virtually any treatment modality. Since our understanding of the molecular complexity is incomplete and criteria for categorisation are limited, we mainly consider the disease RA as group average. A powerful way to gain insight into the complexity of RA has arisen from DNA microarray technology, which allows an open-ended survey to comprehensively identify the genes and biological pathways that are associated with clinically defined conditions. During the last decade encouraging results have been generated towards the molecular description of complex diseases in general. Here, I describe developments in genomics research that provide a framework to increase our understanding of the pathogenesis and the identification of biomarkers for early diagnosis, prognosis and stratification, aimed at a personal medicine approach in RA .

Type I interferons have no major influence on humoral autoimmunity in rheumatoid arthritis

OBJECTIVE

Type I IFNs have recently been implicated in autoantibody-mediated diseases such as SLE. As half the RA patients display a type I IFN(high) signature, we investigated in a pilot study if type I IFN determines the autoantibody response in RA.

METHODS

Serum and peripheral blood cells were obtained from 52 RA patients, with paired samples before and after infliximab treatment in 21 patients. Additional samples were collected from 8 anti-citrullinated protein antibody (ACPA)-positive individuals without arthritis and from 10 ACPA-negative healthy controls. The type I IFN signature was determined by peripheral blood cell gene expression analysis and quantitative RT-PCR. ACPA IgG and IgM, RF IgM, anti-nucleosome IgM and anti-dsDNA were measured by ELISA.

RESULTS

The type I IFN signature was not related to the presence and titers of ACPA and RF during active disease. TNF blockade induced a similar rise of ANAs, and a similar decrease in RF titers in both groups. ACPA IgG and IgM levels appeared to be down-modulated only in the type I IFN(low) group. These changes were independent of the changes in type I IFN response gene activity after TNF blockade. Furthermore, the ACPA response in individuals without arthritis and inflammation was not related to an increase of type I IFN.

CONCLUSIONS

In this explorative study, type I IFN signature does not appear to have a major impact on the humoral autoimmune response in RA. Replication of these data remains warranted.

B lymphocyte autoimmunity in rheumatoid synovitis is independent of ectopic lymphoid neogenesis

B lymphocyte autoimmunity plays a crucial role in the pathogenesis of rheumatoid arthritis. The local production of autoantibodies and the presence of ectopic lymphoid neogenesis in the rheumatoid synovium suggest that these dedicated microenvironments resembling canonical lymphoid follicles may regulate the initiation and maturation of B cell autoimmunity. In this study, we assessed experimentally the relevance of ectopic lymphoid neogenesis for B cell autoimmunity by a detailed structural, molecular, and serological analysis of seropositive and seronegative human synovitis. We demonstrate that synovial lymphoid neogenesis is a reversible process associated with inflammation which is neither restricted to nor preferentially associated with autoantibody positive rheumatic conditions. Despite the abundant expression of key chemokines and cytokines required for full differentiation toward germinal center reactions, synovial lymphoid neogenesis in rheumatoid arthritis only occasionally progresses toward fully differentiated follicles. In agreement with that observation, we could not detect Ag-driven clonal expansion and affinity maturation of B lymphocytes. Furthermore, ectopic lymphoid neogenesis is not directly associated with local production of anti-citrullinated protein Abs and rheumatoid factor in the rheumatoid joint. Therefore, we conclude that synovial lymphoid neogenesis is not a major determinant of these rheumatoid arthritis-specific autoantibody responses.

Responsiveness to anti-tumour necrosis factor alpha therapy is related to pre-treatment tissue inflammation levels in rheumatoid arthritis patients

OBJECTIVE

The response of rheumatoid arthritis (RA) patients to treatment with neutralising antibodies to tumour necrosis factor alpha (TNFalpha) is highly variable. The underlying mechanism for therapy responsiveness is currently unknown. We therefore evaluated the relationship between baseline molecular profiles of synovial tissues from RA patients and the clinical response to treatment with infliximab.

METHODS

Synovial biopsies were obtained by arthroscopy from 18 RA patients with active disease (28 joint count Disease Activity Score (DAS28) > or = 3.2) before initiation of treatment with infliximab. All patients were on stable methotrexate treatment. Clinical response at 16 weeks was defined as a reduction in DAS28 of > or = 1.2, non-response as reduction in DAS28 < 1.2. Large-scale gene expression profiling using microarrays was performed on synovial tissue samples. To identify biological processes in synovial biopsies that could discriminate between responders and non-responders, we performed pathway analysis on the expression profiles.

RESULTS

A total of 12 patients responded to therapy, while 6 patients failed to fulfil the response criteria. We identified several biological processes, related to inflammation, which were up-regulated in patients who responded to therapy, compared to those who did not show clinical improvement.

CONCLUSION

These results indicate that patients with a high level of tissue inflammation are more likely to benefit from anti-TNFalpha treatment.

CCL5 and CCR5 genotypes modify clinical, radiological and pathological features of multiple sclerosis

Chemokines mediate selective recruitment of leukocyte subsets into the CNS during inflammatory episodes. We hypothesised that functional polymorphisms in CCR5 and CCL5 influence perivascular leukocyte infiltration, inflammation, axonal loss, and remyelination, and disease course. Therefore, we determined genotypes at four possibly functional polymorphisms in CCR5 and CCL5 for 637 patients and 92 brain donors with multiple sclerosis (MS). For a subset of 192 patients, MRI data were available. We found that low-producer allele CCL5-403*G was associated with reduced risk of severe axonal loss, whereas high-producer allele CCL5-403*A was associated with a worse clinical disease course measured by the MS Functional Composite Score and MS Severity Score. Low-producer allele CCR5+303*G was associated with reduced T2 hyperintense and T1 hypointense lesion volumes on MRI, and high-producer allele CCR5+303*A with early age at onset. Furthermore, low-producer allele CCR5Delta32 was associated with reduced T2 lesion volume, lower black hole ratio on MRI, and with a higher percentage of lesions with signs of remyelination, histopathologically. In summary, our multifaceted study supports the notion that polymorphisms in CCL5 and CCR5 modify the course of MS.

Rheumatoid arthritis subtypes identified by genomic profiling of peripheral blood cells: assignment of a type I interferon signature in a subpopulation of patients

BACKGROUND

Rheumatoid arthritis (RA) is a heterogeneous disease with unknown cause.

AIM

To identify peripheral blood (PB) gene expression profiles that may distinguish RA subtypes.

METHODS

Large-scale expression profiling by cDNA microarrays was performed on PB from 35 patients and 15 healthy individuals. Differential gene expression was analysed by significance analysis of microarrays (SAM), followed by gene ontology analysis of the significant genes. Gene set enrichment analysis was applied to identify pathways relevant to disease.

RESULTS

A substantially raised expression of a spectrum of genes involved in immune defence was found in the PB of patients with RA compared with healthy individuals. SAM analysis revealed a highly significant elevated expression of interferon (IFN) type I regulated genes in patients with RA compared with healthy individuals, which was confirmed by gene ontology and pathway analysis, suggesting that this pathway was activated systemically in RA. A quantitative analysis revealed that increased expression of IFN-response genes was characteristic of approximately half of the patients (IFN(high) patients). Application of pathway analysis revealed that the IFN(high) group was largely different from the controls, with evidence for upregulated pathways involved in coagulation and complement cascades, and fatty acid metabolism, while the IFN(low) group was similar to the controls.

CONCLUSION

The IFN type I signature defines a subgroup of patients with RA, with a distinct biomolecular phenotype, characterised by increased activity of the innate defence system, coagulation and complement cascades, and fatty acid metabolism.

A subtype of multiple sclerosis defined by an activated immune defense program

Given the heterogeneous nature of multiple sclerosis (MS), we applied DNA microarray technology to determine whether variability is reflected in peripheral blood (PB) cells. In this study, we studied whole-blood gene expression profiles of 29 patients with relapsing-remitting MS (RRMS) and 25 age- and sex-matched healthy controls. We used microarrays with a complexity of 43K cDNAs. The data were analyzed using sophisticated pathway-level analysis in order to provide insight into the deregulated peripheral immune response programs in MS. We found a remarkable elevated expression of a spectrum of genes known to be involved in immune defense in the PB of MS patients compared to healthy individuals. Cluster analysis revealed that the increased expression of these genes was characteristic for approximately half of the patients. In addition, the gene signature in this group of patients was comparable with a virus response program. We conclude that the transcriptional signature of the PB cells reflects the heterogeneity of MS and defines a sub-population of RRMS patients, who exhibit an activated immune defense program that resembles a virus response program, which is supportive for a link between viruses and MS.

Differentially methylated alleles in a distinct region of the human interleukin-1alpha promoter are associated with allele-specific expression of IL-1alpha in CD4+ T cells

Cytokine secretion profiles of activated T cells are critical for maintaining the immunologic balance between protection and tolerance. In mice, several cytokines have been reported to exhibit monoallelic expression. Previously, we found that the human interleukin-1 alpha (IL1A) gene exhibits a stable allele-specific expression pattern in CD4+ T-cell clones. We investigated whether DNA methylation is involved in the allele-specific expression of IL-1alpha. Here, we show that differential methylation of CpGs in the proximal promoter region is associated with allele-specific expression of IL-1alpha in CD4+ T cells. The differential methylation pattern is already observed in naive T cells. In keratinocytes, which constitutively produce IL-1alpha, the proximal promoter is hypomethylated. CpGs located further upstream and in intron 4 were almost all methylated, irrespective of expression. Treatment of nonexpressing cells and of T-cell clones with 5-aza-2'deoxycytidine induced IL-1alpha expression in the nonexpressing cells and induced expression of the formerly silent allele in T-cell clones. In addition, electrophoretic mobility shift assays showed that methylation of CpGs in the proximal promoter resulted in direct inhibition of binding of nuclear factor(s). Taken together, these results suggest that allele-specific expression of IL-1alpha in CD4+ cells is achieved, at least in part, by differential methylation of the promoter.

[Molecular unraveling of disease by means of DNA-microarrays]

Determination of the human genome sequence and the development of microarray technologies allowing the rapid measurement of all genes in the genome have generated new perspectives for our current biomedical research. Gene expression analysis will make a major contribution to our insight into the underlying biology of disease and will lead to improved methods for diagnostics, prognosis and treatment. Microarray studies create the possiblity to subclassify patients with diseases such as rheumatoid arthritis, diffuse large B-cell lymphoma and breast cancer, with both prognostic and therapeutic consequences. The simultaneous quantification of the activity of all genes in tissues or cells from patients by microarray technology, linked to the clinical parameters, creates a large number of data points, which cannot be analysed without the aid of the advanced application of bioinformatics. As a result, genomic research has become, in part, a bioinformatics discipline that will be integrated with clinical medicine. The microarray technology makes it possible to develop personalized medicine, with a more accurate diagnosis and prognosis for every patient and subsequently a tailored treatment strategy.

Is there a future for TNF promoter polymorphisms?

The in vitro study of TNF promoter polymorphism (SNP) function was stimulated by the numerous case-control (association) studies of the polymorphisms in relation to human disease and the appearance of several studies claiming to show a functional role for these SNPs provided a further impetus to researchers interested in the role of TNF in their disease of interest. In this review we consider case-control studies, concentrating on the autoimmune and inflammatory diseases rheumatoid arthritis, multiple sclerosis, ankylosing spondylitis, and asthma, and on infectious diseases including malaria, hepatitis B and C infection, leprosy and sepsis/septic shock. We also review the available evidence on the functional role of the various TNF promoter polymorphisms. In general, case-control studies have produced mixed results, with little consensus in most cases on whether any TNF polymorphisms are actually associated with disease, although results have been more consistent in the case of infectious diseases, particularly malaria. Functional studies have also produced mixed results but recent work suggests that the much studied -308G/A polymorphism is not functional, while the function of other TNF polymorphisms remains controversial. Studies of the TNF region are increasingly using extended haplotypes that can better capture the variation of the MHC region.

Activation of the STAT1 pathway in rheumatoid arthritis

BACKGROUND

Expression of signal transducer and activator of transcription 1 (STAT1), the mediator of interferon (IFN) signalling, is raised in synovial tissue (ST) from patients with rheumatoid arthritis (RA).

OBJECTIVES

To determine the extent to which this pathway is activated by phosphorylation in RA synovium. Additionally, to investigate the cellular basis of STAT1 activation in RA ST.

METHODS

ST specimens from 12 patients with RA and 14 disease controls (patients with osteoarthritis and reactive arthritis) were analysed by immunohistochemistry, using antibodies to STAT1, tyrosine phosphorylated STAT1, and serine phosphorylated STAT1. Lysates of cultured fibroblast-like synoviocytes stimulated with IFNbeta were analysed by western blotting. Phenotypic characterisation of cells expressing STAT1 in RA ST was performed by double immunolabelling for STAT1 and CD3, CD22, CD55, or CD68.

RESULTS

Raised levels of total STAT1 protein and both its activated tyrosine and serine phosphorylated forms were seen in RA synovium as compared with controls. STAT1 was predominantly abundant in T and B lymphocytes in focal inflammatory infiltrates and in fibroblast-like synoviocytes in the intimal lining layer. Raised levels of STAT1 are sustained in cultured RA compared with OA fibroblast-like synoviocytes, and STAT1 serine and tyrosine phosphorylation is rapidly induced upon stimulation with IFNbeta.

CONCLUSION

These results demonstrate activation of the STAT1 pathway in RA synovium by raised STAT1 protein expression and concomitantly increased tyrosine (701) and serine (727) phosphorylation. High expression of STAT1 is intrinsic to RA fibroblast-like synoviocytes in the intimal lining layer, whereas activation of the pathway by phosphorylation is an active process.

Autoantibodies to cyclic citrullinated peptides predict progression to rheumatoid arthritis in patients with undifferentiated arthritis: a prospective cohort study

OBJECTIVE

Rheumatoid arthritis (RA) is a common, severe, chronic inflammatory joint disease. Since the disease may initially be indistinguishable from other forms of arthritis, early diagnosis can be difficult. Autoantibodies seen in RA can be detected years before clinical symptoms develop. In an inception cohort of patients with recent-onset arthritis, we undertook this study to assess the predictive value of RA-specific autoantibodies to cyclic citrullinated peptides (CCPs) in patients with undifferentiated arthritis (UA).

METHODS

Anti-CCP2 antibody tests were performed at baseline in 936 consecutive, newly referred patients with recent-onset arthritis. Patients who could not be properly classified 2 weeks after inclusion were categorized as having UA. Patients with UA were followed up for 3 years and evaluated for progression of their disease to RA as defined by the American College of Rheumatology (ACR) 1987 revised criteria.

RESULTS

Three hundred eighteen of 936 patients with recent-onset arthritis were classified as having UA and were available for analysis. After 3 years of followup, 127 of 318 UA patients (40%) had been classified as having RA. RA had developed in 63 of 249 patients (25%) with a negative anti-CCP test and in 64 of 69 patients (93%) with a positive anti-CCP test (odds ratio 37.8 [95% confidence interval 13.8-111.9]). Multivariate analysis of the presence of anti-CCP antibodies and parameters from the ACR criteria identified polyarthritis, symmetric arthritis, erosions on radiographs, and anti-CCP antibodies as significant predictors of RA.

CONCLUSION

Testing for anti-CCP antibodies in UA allows accurate prediction of a substantial number of patients who will fulfill the ACR criteria for RA.

Association of autoantibodies to glucose-6-phosphate isomerase with extraarticular complications in rheumatoid arthritis

OBJECTIVE

In the K/BxN mouse model, autoantibodies against glucose-6-phosphate isomerase (GPI) cause arthritis. The relevance of this model for human disease remains a subject of controversy. We set out to determine whether GPI autoantibodies occur in patients with rheumatoid arthritis (RA) and, if so, at what stage of the RA.

METHODS

Using an enzyme-linked immunosorbent assay, serum from 131 RA patients and 28 healthy controls was tested for autoantibodies against recombinant human GPI. Patients were grouped according to disease duration and presence of rheumatoid nodules, rheumatoid vasculitis, and Felty's syndrome, which are extraarticular complications of RA.

RESULTS

Elevated levels of autoantibodies against GPI were present in 5% of patients with uncomplicated RA and 4% of controls. In RA complicated by extraarticular manifestations, anti-GPI antibodies were observed in 18% of patients with rheumatoid nodules, 45% of patients with rheumatoid vasculitis, and 92% of patients with Felty's syndrome.

CONCLUSION

In patients with RA, autoantibodies to GPI are associated with the occurrence of extraarticular complications.

Association between polymorphisms in the human chemokine receptor genes CCR2 and CX3CR1 and rheumatoid arthritis

Cell trafficking into the rheumatoid synovium is thought to play an important role in the inflammation seen in rheumatoid arthritis. Chemokine receptors play a central role in this process, and several common variants are known, including the CCR2 variant, CCR2-64I, and two variants of the CX3CR1 gene, V249I and T280M. All three variants result in functional amino acid substitutions. We studied the association of these chemokine receptor variants with susceptibility to and severity of rheumatoid arthritis in two Dutch patient populations; 282 consecutive rheumatoid arthritis patients from a rheumatology outpatient clinic, and a cohort of 101 female rheumatoid arthritis patients, followed closely for a 12-year period, from whom hand and feet X-rays taken at three year intervals were scored and analyzed in this study. Although there was a trend towards increased severity of disease in patients carrying CX3CR1 variants, this was not independent of known risk factors. We found no evidence for a significant independent role for the CCR2 and CX3CR1 variants in the susceptibility to or severity of rheumatoid arthritis.

Association of polymorphisms of the tumour necrosis factor receptors I and II and rheumatoid arthritis

OBJECTIVE

To assess the role of polymorphisms of the tumour necrosis factor (TNF) receptors, TNF-RI (p55) and TNF-RII (p75) in the susceptibility to and severity of rheumatoid arthritis (RA) in Dutch patients.

METHODS

A total of 319 consecutive RA patients, and a cohort of 90 female RA patients with detailed 12-yr follow-up were genotyped for the TNF-RI exon 1 (+36 A to G) and TNF-RII 3' UTR (+1690 T to C) polymorphisms.

RESULTS

The frequencies of the TNF-RI and TNF-RII polymorphisms were determined in both patient groups and healthy controls, but no significant differences were found. To determine the relationship of these polymorphisms to disease severity, the extent of joint damage in the cohort of 90 female RA patients was analysed. No differences in severity were observed.

CONCLUSION

These TNF-RI and TNF-RII polymorphisms were not found to be associated with susceptibility to or severity of RA in the Dutch population.

Discovery of distinctive gene expression profiles in rheumatoid synovium using cDNA microarray technology: evidence for the existence of multiple pathways of tissue destruction and repair

Rheumatoid arthritis (RA) is a heterogeneous disease. We used cDNA microarray technology to subclassify RA patients and disclose disease pathways in rheumatoid synovium. Hierarchical clustering of gene expression data identified two main groups of tissues (RA-I and RA-II). A total of 121 genes were significantly higher expressed in the RA-I tissues, whereas 39 genes were overexpressed in the RA-II tissues. Among the 121 genes overexpressed in RA-I tissues, a relative majority of nine genes are located on chromosome 6p21.3. An interpretation of biological processes that take place revealed that the gene expression profile in RA-I tissues is indicative for an adaptive immune response. The RA-II group showed expression of genes suggestive for fibroblast dedifferentiation. Within the RA-I group, two subgroups could be distinguished; the RA-Ia group showed predominantly immune-related gene activity, while the RA-Ib group showed an additional higher activity of genes indicative for the classical pathway of complement activation. All tissues except the RA-Ia subgroup showed elevated expression of genes involved in tissue remodeling. These results confirm the heterogeneous nature of RA and suggest the existence of distinct pathogenic mechanisms that contribute to RA. The differences in expression profiles provide opportunities to stratify patients based on molecular criteria.

Human IgG Fc-binding phage antibodies constructed from synovial fluid CD38+ B cells of patients with rheumatoid arthritis show the imprints of an antigen-dependent process of somatic hypermutation and clonal selection

The persistent presence of rheumatoid factors (RFs) in the circulation is a characteristic phenomenon in patients with rheumatoid arthritis (RA). Recent data indicate that RFs associated with seropositive RA are derived from terminally differentiated CD20-, CD38+ plasma cells (PCs) present in synovial fluids of the inflamed joints. These cells were shown to secrete RFs actively and are thought to originate from germinal centre (GC)-like structures present in the inflamed synovium. To obtain a representative image of the structural properties of IgM and IgG RFs associated with RA, phage antibody display libraries were constructed from CD38+ PCs isolated from the inflamed joints of RF-seropositive patients with RA. Subsequently, human IgG Fc-binding monoclonal phage antibodies were selected and analysed. The data suggest that RA-associated RFs are encoded by a diverse set of VL and a more restricted set of VH regions. VH gene family usage of PC-derived IgM- and IgG-RFs was found to be restricted to the VH1 and 3 gene families, with a preference for VH3, and many different VL genes were shown to contribute to RF specificity. Clonally related VH as well as VL sequences were identified, based on the presence of identical CDR3 regions and shared somatic mutations. In this B cell selection process base-pair substitutions as well as deletions of triplets in CDR regions, leaving the transcripts in frame, were involved. Together, these data provide further evidence for an Ag-driven immune response in the terminal differentiation into RF-producing PCs in patients with RA, including expansion of clonally related B cells, selection and isotype switching, all hallmarks of a GC reaction.

Polyreactivity of human IgG Fc-binding phage antibodies constructed from synovial fluid CD38+ B cells of patients with rheumatoid arthritis

Recent data indicate that rheumatoid factors (RFs) that occur in patients with rheumatoid arthritis (RA) are derived from Ig-producing terminally differentiated CD20-, CD38+ plasma cells present in synovial fluids (SFs). Phage antibody display libraries were constructed using CD38+ plasma cells isolated from SFs of two RF-seropositive RA patients. The libraries were enriched for phage antibodies (Phabs) binding to human IgG (HuIgG) Fc fragments and the sequences of their V genes were analysed. These data provided further evidence for an Ag-driven immune response in patients with RA, including expansion of clonally related B cells, selection and isotype switching, all hallmarks of a germinal center reaction. In the present study, the functional characteristics of these HuIgG Fc-binding monoclonal (mo) Phabs were further analysed in order to provide more insight into the specificity of HuIgG Fc-binding Phabs. Remarkably, all HuIgG Fc-binding moPhabs tested (n=48; derived from four different libraries) displayed polyreactivity. Structural analysis of the CDR3 regions revealed characteristic features of polyreactive Igs. Most H chain CDR3 regions harboured tryptophan/tyrosine-rich parts and approximately 60% of the L chain CDR3 regions of both RA patients displayed an identical stretch of amino acids (W/Y-D-S-S). Supportive for a dominant role of VH in specificity, exchange of VL regions with a single VH region yielded moPhabs with similar specificities. All together, the data suggest the presence of an Ag-driven process in the joints of patients with RA, including somatic mutation and clonal selection entailing isotype switching, resulting in the differentiation of B cells into polyreactive RF-secreting plasma cells.

Chronic obstructive pulmonary disease is associated with the -1055 IL-13 promoter polymorphism

IL-13 is strongly implicated in the development of asthma and chronic obstructive pulmonary disease (COPD). We previously identified an IL-13 promoter polymorphism (-1055 C to T) that is associated with allergic asthma. We now report an increased frequency of the -1055 T allele in COPD patients compared to healthy controls (P=0.002) and compared to a second control group consisting of smoking individuals with normal lung function (P=0.01). A closely linked IL-13 exon polymorphism is present at normal allelic frequencies (P=0.3 and 0.4, respectively). In addition, we observed a normal distribution of two IL-4 polymorphisms at positions -590 and +33 (P=0.2 and 0.9, respectively). These results could implicate a functional role for the IL-13 promoter polymorphism in the enhanced risk to develop COPD.

Relationship of polymorphisms of the Interleukin-1 gene cluster to occurrence and severity of rheumatoid arthritis

Interleukin-1 (IL-1) has been implicated in the pathogenesis of rheumatoid arthritis (RA). We investigated whether IotaL-1 gene locus polymorphisms are associated with susceptibility to or severity of RA. Genotyping for IL-1alpha, IL-1beta and IL-1Ra single nucleotide polymorphisms (SNPs) performed in a cross-sectional group of 312 consecutive RA patients (RA-group 1) and a cohort of 94 incident female RA patients (RA-group 2) revealed that the rare IL-1RN + 2017 C allele was significantly increased in RA compared to controls (n = 245). A retrospective analysis in RA-group 1 showed no significant associations between IL-1 genotypes and disease severity. A prospective study in RA-group 2 demonstrated that the extent of joint destruction over 12 years was higher in patients genotyped heterozygous for the IL-1 A + 4845, IL-1B + 3953 and IL-1RN + 5111 SNPs compared to homozygous wildtype patients, although differences did not reach statistical significance. These data indicate that the IL-1RN + 2017 polymorphism is associated with susceptibility to RA.

Tumor necrosis factor-alpha gene polymorphisms in relation to periodontitis

BACKGROUND

Genetic polymorphisms for cytokines have been proposed as potential genetic markers for destructive periodontal disease. The present aim was to investigate 4 bi-allelic polymorphisms in the TNF-alpha gene in relation to susceptibility for and severity of periodontitis. The polymorphisms were all transitions from G to A, 3 in the promoter positions: -376, -308, -238; and one in the first intron at position +489.

METHODS

90 periodontitis patients and 264 reference control subjects were genotyped and frequencies of genotypes and alleles were analyzed. Also genotype frequencies among severe and moderate periodontitis patients were explored, and the % of teeth with 50% bone loss and the % of teeth without any bone loss for patients with the A allele (A+ genotype) and patients without (A- genotype) were compared.

RESULTS

The distributions of genotypes and frequencies of A allele carriage rates for the 4 TNF-alpha polymorphisms were not different between patients and reference controls; Hardy-Weinberg equilibrium criteria were fulfilled. Also the distribution of A+ and A- genotypes, alone or in combinations, were not different for severe periodontitis compared to moderate periodontitis patients. None of the A+ genotypes showed a significant different bone loss pattern compared to A- genotype patients. Smoking status of the patients did not influence the results.

CONCLUSIONS

Genetic polymorphisms in the TNF-alpha gene at positions -376, -308, -238 and +489 could not be identified as susceptibility or severity factors in periodontitis, irrespective of the smoking status of the patients.

Silencer activity of NFATc2 in the interleukin-12 receptor beta 2 proximal promoter in human T helper cells

Interleukin 12 (IL-12) is a potent enhancer of interferon gamma production by activated T cells. The high-affinity IL-12 receptor (IL-12R) is a heterodimer of a beta1 and a beta2 subunit. Expression of the signaling IL-12Rbeta2 chain is usually low, as compared with the more abundant beta1 chain, and may be rate-limiting for IL-12 sensitivity. Little is known about the mechanisms controlling IL-12Rbeta2 gene expression. Reporter gene assays in IL-12Rbeta2-expressing Jurkat cells showed that truncation of the region from -151 to -61 abrogated promoter activity. The proximal promoter region does not contain a typical TATA box, suggesting a role for SP-1. Indeed, mutagenesis of the -63 SP-1 consensus site decreased transcription by 50%. Electrophoretic mobility shift experiments confirmed the binding of SP-1 and SP-3 at this site. In contrast, truncation of -252 to -192 increased promoter activity. Likewise, mutagenesis of the consensus nuclear factor of activated T cells site at -206 increased promoter activity by 70%, suggesting silencer activity of this element. Electrophoretic mobility shift experiments with primary Th (T helper) cells showed the formation of a specific, T-cell receptor-inducible complex at this site that is sensitive to cyclosporin A and supershifted with anti-NFATc2 in both Th1 and Th2 cells. Accordingly, cyclosporin A dose-dependently increased IL-12Rbeta2 mRNA expression. These first data on IL-12Rbeta2 gene regulation indicate a TATA-less promoter, depending on SP-1/SP-3 transcription factors, and a negative regulatory NFAT element at -206. This element may contribute to the overall low level of IL-12Rbeta2 expression on Th cells.

Presence of a population of CD20+, CD38- B lymphocytes with defective proliferative responsiveness in the synovial compartment of patients with rheumatoid arthritis

OBJECTIVE

To provide a comprehensive understanding of the humoral immune response that takes place at the site of inflammation in rheumatoid arthritis (RA), we studied the functional properties of synovial B cells. In particular, the response to various modes of mitogen stimulation was investigated.

METHODS

Purified synovial fluid (SF) B cells were cultured in the presence of CD40 ligand (CD40L)-expressing fibroblasts and cytokines, activated T cells, or phorbol myristate acetate (PMA)/ionomycin. Proliferation was determined by 3H-thymidine incorporation. Release of intracellular calcium was studied by flow cytometry.

RESULTS

The inflamed joints of RA patients contained a population of CD20+,CD38- B cells with dramatically impaired mitogen responsiveness. Although the Ig-producing capacity was intact, these cells failed to proliferate in response to (a) CD40 in the presence of interleukin-2 (IL-2) and IL-10, (b) activated T cells, or (c) stimulation via the B cell receptor. Moreover, SF CD20+,CD38- B cells revealed a defective B cell receptor-induced Ca2+ influx, reminiscent of anergic B cells. Release of intracellular Ca2+ by ionomycin in the presence of the protein kinase C activator PMA did not restore the proliferative capacity. These findings indicate blockades in the proximal and distal intermediates involved in mitogen signaling.

CONCLUSION

SF CD20+,CD38- B cells have functionally impaired proliferative responsiveness. The capacity of these cells to respond to activation by the production of Ig supports the notion that these cells might serve as Ig-producing effector cells and, as such, play a role in the pathophysiology of RA.

Functional analysis of linker-scan mutants spanning the -376, -308, -244, and -238 polymorphic sites of the TNF-alpha promoter

Tumor necrosis factor alpha (TNF-alpha) promoter polymorphisms have been linked to a large number of diseases but studies examining the possible direct functional effects of these polymorphisms have been contradictory. Previous studies compared TNF-alpha promoter constructs containing single nucleotide changes. We have now made a series of mutant constructs in which regions of the TNF-alpha promoter containing suspected functional single nucleotide polymorphisms, including -376, -308, -244 and -238, were replaced by a 10 bp linker scan sequence. These constructs were transiently transfected into the T cell line Jurkat, the B cell line Raji, and the monocytic cell line U937, and tested for basal and induced transcriptional activity. Mutant constructs covering both the -308 and -376 polymorphisms showed no significant differences in either basal or induced transcriptional activity. Constructs covering the -244/-238 region showed a small increase in basal activity in the U937 cell line. These results indicate (i) that the -308 and -376 regions are of no functional relevance for TNF-alpha promoter transcription, and (ii) that the -244/-238 region does not influence transcription in some cell lines but may have some role in transcription in others.

Allele-specific quantification of tumor necrosis factor alpha (TNF) transcription and the role of promoter polymorphisms in rheumatoid arthritis patients and healthy individuals

Interindividual variation in the expression of tumor necrosis factor alpha (TNF) suggests the existence of functionally distinct TNF alleles that could play a role in susceptibility to TNF associated diseases such as rheumatoid arthritis (RA). To determine whether differential expression of TNF alleles exists, the relative contribution of TNF alleles in total TNF RNA production in peripheral blood mononuclear cells (PBMC) of healthy individuals and synovial tissue of RA patients was analyzed. By using a Tai I restriction fragment length polymorphism (RFLP) located at position +489 in the first intron of the gene, the relative contribution of each allele in precursor transcript production in heterozygous individuals could be measured. By means of this method we studied whether differences exist between TNF alleles in TNF pre-mRNA production. The relative contribution of TNF alleles to the non-spliced RNA pool was measured in PBMC of healthy individuals which were stimulated with LPS, PMA and anti-CD3 and anti-CD28 monoclonal antibodies for different time periods. Moreover, synovial biopsy material of RA patients was analyzed. The results of this study do not reveal a difference in the contribution of distinct TNF alleles in TNF pre-mRNA production upon in vitro and physiological stimulation conditions in healthy individuals and RA patients. Since some of the individuals whose PBMC were tested were also heterozygous for either -308, -1031, -863, -857 TNF promoter/enhancer single nucleotide polymorphisms (SNPs), the data argue against functional relevance of these TNF promoter/enhancer SNPs in the regulation of transcription. In conclusion, the data do not provide evidence for the existence of transcriptionally distinct TNF alleles to explain interindividual variation in TNF expression.

Differential requirements for induction of total immunoglobulin and physiological rheumatoid factor production by human peripheral blood B cells

Rheumatoid factors (RFs) are autoantibodies directed against the Fc part of IgG. Considerable evidence exists that there are two classes of RFs, pathological and physiological. Whereas pathological RFs are associated with disease, physiological RFs are considered to be a normal component of the immune response. RF(+) precursor B cells present as part of the B cell repertoire of healthy individuals are held responsible for the production of physiological RFs, which is a transient phenomenon with a clear correlation with an initiating stimulus such as immunization or exposure to an infection. Here we demonstrate a difference in the regulatory control of total Ig and RF production by peripheral blood (PB) B cells of both healthy controls (HC) and patients with rheumatoid arthritis (RA). Highly purified B cells from HC and patients with RA were cocultured with T cells stimulated with immobilized anti-CD3 mAb. Similar to IgM production, IgM-RF production was shown to be dependent on CD40 cross-linking. However, activation of PB B cells in the CD40 system in the presence of IL-2, IL-4, IL-10, combinations of these cytokines or supernatant of anti-CD3-stimulated T cells failed to induce detectable IgM-RF, whereas total IgM production was considerable. From these results we conclude that conditions to activate physiological RF(+) B cells require additional contact besides CD40--CD40L interactions between T and B cells. Since the requirements for RF production were similar using PB B cells from HC and patients with RA it is suggested that the regulatory properties of RF(+) precursors in the PB B cell compartment is equal among these groups. Together, these results indicate that conditions for the induction of total Ig and physiological RFs are different.

Secretion of anti-citrulline-containing peptide antibody by B lymphocytes in rheumatoid arthritis

OBJECTIVE

To understand the regulation of anti-citrulline-containing peptide antibody (anti-CCP) production in rheumatoid arthritis (RA), production of anti-CCP by B cells derived from peripheral blood (PB), bone marrow (BM), and synovial fluid (SF) was examined.

METHODS

Purified PB and SF B cells were isolated by negative selection and then cultured in the absence or presence of L-CD40 ligand cells and interleukin-10 or anti-CD3-activated T cells. Total IgM and IgM-anti-CCP were detected after 14 days of culture by enzyme-linked immunosorbent assay. Enzyme-linked immunospot assays were performed to analyze the frequency of cells that spontaneously produced IgM-anti-CCP in BM and SF B cells.

RESULTS

IgM-anti-CCP autoantibodies were induced in PB B cells from healthy controls and RA patients following coculture with activated T cells or application of the CD40 activation system, whereas no production could be detected when PB B cells were cultured in the absence of a stimulus. SF and BM B cells from anti-CCP-seropositive RA patients, but not anti-CCP-seronegative patients, actively produced IgM-anti-CCP without stimulation. The frequency of spontaneous production of IgM-anti-CCP among the IgM-secreting cells ranged from 2.2% to 25%.

CONCLUSION

These results indicate the presence of B cell precursors for anti-CCP autoantibodies that are able to produce antibodies upon stimulation in the PB B cell repertoire of healthy controls and patients with RA. In contrast, B cells that actively secreted anti-CCP were specifically present in the BM and SF compartment of anti-CCP-seropositive RA patients. The local presence of anti-CCP-secreting cells in the inflamed joints provides evidence for an antigen-driven maturation of CCP-specific B cells at the site of inflammation in RA.

Are differences in interleukin 10 production associated with joint damage?

OBJECTIVE

Constitutive differences between individuals in cytokine production may determine the variation in the course of inflammatory arthritis.

METHODS

The association between interleukin 10 (IL-10) production and joint destruction was studied by comparing IL-10 mRNA content in synovial biopsies from seven patients with destructive joint disease and six patients with non-destructive joint disease. The IL-10 mRNA content was 0.4 +/- 0.6 arbitrary units in erosive joints compared with 2.3 +/- 1.2 arbitrary units in non-erosive joints (P: < 0.03, Mann-Whitney U:-test). As this difference suggested that IL-10 production was associated with joint destruction, we tested whether the IL-10 locus determined the extent of joint damage.

RESULTS

Innate differences in IL-10 production are locus-dependent. In line with these data, we showed that innate differences in IL-10 protein production were also present as differences in IL-10 mRNA levels. We tested if polymorphisms in the promoter of IL-10 were associated with the extent of joint damage.

DISCUSSION

In a cohort study of female rheumatoid arthritis patients followed for 12 yr, the extent of joint destruction differed significantly between patients with different IL-10 genotypes. In patients with the -1082AA genotype who were studied prospectively, the mean increase in radiographic damage score (modified Sharp score of X-rays of hands and feet) during the first 6 yr was 9 +/- 9 per yr vs 19 +/- 16 per yr for patients with the genotype -1082GG (P: < 0.02). In line with these data, cultures of endotoxin-stimulated whole blood from 158 donors showed that the presence of the allele associated with less joint destruction correlated with slightly higher IL-10 production.

CONCLUSIONS

Both the immunogenetic and the synovial biopsies suggest that a variation in IL-10 production is associated with joint destruction.