Association between tumor necrosis factor receptor II and familial, but not sporadic, rheumatoid arthritis: evidence for genetic heterogeneity

Macrophage-derived cytokines in pneumonia: Linking cellular immunology and genetics

Macrophages represent the first line of anti-pathogen defense - they encounter invading pathogens to perform the phagocytic activity, to deliver the plethora of pro- and anti-inflammatory cytokines, and to shape the tissue microenvironment. Throughout pneumonia course, alveolar macrophages and infiltrated blood monocytes produce increasing cytokine amounts, which activates the antiviral/antibacterial immunity but can also provoke the risk of the so-called cytokine "storm" and normal tissue damage. Subsequently, the question of how the cytokine spectrum is shaped and balanced in the pneumonia context remains a hot topic in medical immunology, particularly in the COVID19 pandemic era. The diversity in cytokine profiles, involved in pneumonia pathogenesis, is determined by the variations in cytokine-receptor interactions, which may lead to severe cytokine storm and functional decline of particular tissues and organs, for example, cardiovascular and respiratory systems. Cytokines and their receptors form unique profiles in individual patients, depending on the (a) microenvironmental context (comorbidities and associated treatment), (b) lung monocyte heterogeneity, and (c) genetic variations. These multidisciplinary strategies can be proactively considered beforehand and during the pneumonia course and potentially allow the new age of personalized immunotherapy.

Treg cell-based therapies: challenges and perspectives

Cellular therapies using regulatory T (Treg) cells are currently undergoing clinical trials for the treatment of autoimmune diseases, transplant rejection and graft-versus-host disease. In this Review, we discuss the biology of Treg cells and describe new efforts in Treg cell engineering to enhance specificity, stability, functional activity and delivery. Finally, we envision that the success of Treg cell therapy in autoimmunity and transplantation will encourage the clinical use of adoptive Treg cell therapy for non-immune diseases, such as neurological disorders and tissue repair.

SMAC mimetics and RIPK inhibitors as therapeutics for chronic inflammatory diseases

New therapeutic approaches for chronic inflammatory diseases such as inflammatory bowel disease, rheumatoid arthritis, and psoriasis are needed because current treatments are often suboptimal in terms of both efficacy and the risks of serious adverse events. Inhibitor of apoptosis proteins (IAPs) are E3 ubiquitin ligases that inhibit cell death pathways and are themselves inhibited by second mitochondria-derived activator of caspases (SMAC). SMAC mimetics (SMs), small-molecule antagonists of IAPs, are being evaluated as cancer therapies in clinical trials. IAPs are also crucial regulators of inflammatory pathways because they influence both the activation of inflammatory genes and the induction of cell death through the receptor-interacting serine-threonine protein kinases (RIPKs), nuclear factor κB (NF-κB)-inducing kinase, and mitogen-activated protein kinases (MAPKs). Furthermore, there is an increasing interest in specifically targeting the substrates of IAP-mediated ubiquitylation, especially RIPK1, RIPK2, and RIPK3, as druggable nodes in inflammation control. Several studies have revealed an anti-inflammatory potential of RIPK inhibitors that either block inflammatory signaling or block the form of inflammatory cell death known as necroptosis. Expanding research on innate immune signaling through pattern recognition receptors that stimulate proinflammatory NF-κB and MAPK signaling may further contribute to uncovering the complex molecular roles used by IAPs and downstream RIPKs in inflammatory signaling. This may benefit and guide the development of SMs or selective RIPK inhibitors as anti-inflammatory therapeutics for various chronic inflammatory conditions.

Anti-TNF Therapy in Spondyloarthritis and Related Diseases, Impact on the Immune System and Prediction of Treatment Responses

Immune-mediated inflammatory diseases (IMIDs), such as spondyloarthritis (SpA), psoriasis, Crohn's disease (CD), and rheumatoid arthritis (RA) remain challenging illnesses. They often strike at a young age and cause lifelong morbidity, representing a considerable burden for the affected individuals and society. Pioneering studies have revealed the presence of a TNF-dependent proinflammatory cytokine cascade in several IMIDs, and the introduction of anti-TNF therapy 20 years ago has proven effective to reduce inflammation and clinical symptoms in RA, SpA, and other IMID, providing unprecedented clinical benefits and a valid alternative in case of failure or intolerable adverse effects of conventional disease-modifying antirheumatic drugs (DMARDs, for RA) or non-steroidal anti-inflammatory drugs (NSAIDs, for SpA). However, our understanding of how TNF inhibitors (TNFi) affect the immune system in patients is limited. This question is relevant because anti-TNF therapy has been associated with infectious complications. Furthermore, clinical efficacy of TNFi is limited by a high rate of non-responsiveness (30–40%) in RA, SpA, and other IMID, exposing a substantial fraction of patients to side-effects without clinical benefit. Despite the extensive use of TNFi, it is still not possible to determine which patients will respond to TNFi before treatment initiation. The recent introduction of antibodies blocking IL-17 has expanded the therapeutic options for SpA, as well as psoriasis and psoriatic arthritis. It is therefore essential to develop tools to guide treatment decisions for patients affected by SpA and other IMID, both to optimize clinical care and contain health care costs. After a brief overview of the biology of TNF, its receptors and currently used TNFi in the clinics, we summarize the progress that has been made to increase our understanding of the action of TNFi on the immune system in patients. We then summarize efforts dedicated to identify biomarkers that can predict treatment responses to TNFi and we conclude with a section dedicated to the recently introduced inhibitors of IL-17A and IL-23 in SpA and related diseases. The focus of this review is on SpA, however, we also refer to RA on topics for which only limited information is available on SpA in the literature.

Role of TNF-TNF Receptor 2 Signal in Regulatory T Cells and Its Therapeutic Implications

Tumor necrosis factor α (TNFα) is a pleiotropic cytokine which signals through TNF receptor 1 (TNFR1) and TNF receptor 2 (TNFR2). Emerging evidence has demonstrated that TNFR1 is ubiquitously expressed on almost all cells, while TNFR2 exhibits a limited expression, predominantly on regulatory T cells (Tregs). In addition, the signaling pathway by sTNF via TNFR1 mainly triggers pro-inflammatory pathways, and mTNF binding to TNFR2 usually initiates immune modulation and tissue regeneration. TNFα plays a critical role in upregulation or downregulation of Treg activity. Deficiency in TNFR2 signaling is significant in various autoimmune diseases. An ideal therapeutic strategy for autoimmune diseases would be to selectively block the sTNF/TNFR1 signal through the administration of sTNF inhibitors, or using TNFR1 antagonists while keeping the TNFR2 signaling pathway intact. Another promising strategy would be to rely on TNFR2 agonists which could drive the expansion of Tregs and promote tissue regeneration. Design of these therapeutic strategies targeting the TNFR1 or TNFR2 signaling pathways holds promise for the treatment of diverse inflammatory and degenerative diseases.

Immunomodulation of autoimmune arthritis by pro-inflammatory cytokines

Pro-inflammatory cytokines promote autoimmune inflammation and tissue damage, while anti-inflammatory cytokines help resolve inflammation and facilitate tissue repair. Over the past few decades, this general feature of cytokine-mediated events has offered a broad framework to comprehend the pathogenesis of autoimmune and other immune-mediated diseases, and to successfully develop therapeutic approaches for diseases such as rheumatoid arthritis (RA). Anti-tumor necrosis factor-α (TNF-α) therapy is a testimony in support of this endeavor. However, many patients with RA fail to respond to this or other biologics, and some patients may suffer unexpected aggravation of arthritic inflammation or other autoimmune effects. These observations combined with rapid advancements in immunology in regard to newer cytokines and T cell subsets have enforced a re-evaluation of the perceived pathogenic attribute of the pro-inflammatory cytokines. Studies conducted by others and us in experimental models of arthritis involving direct administration of IFN-γ or TNF-α; in vivo neutralization of the cytokine; the use of animals deficient in the cytokine or its receptor; and the impact of the cytokine or anti-cytokine therapy on defined T cell subsets have revealed paradoxical anti-inflammatory and immunoregulatory attributes of these two cytokines. Similar studies in other models of autoimmunity as well as limited studies in arthritis patients have also unveiled the disease-protective effects of these pro-inflammatory cytokines. A major mechanism in this regard is the altered balance between the pathogenic T helper 17 (Th17) and protective T regulatory (Treg) cells in favor of the latter. However, it is essential to consider that this aspect of the pro-inflammatory cytokines is context-dependent such that the dose and timing of intervention, the experimental model of the disease under study, and the differences in individual responsiveness can influence the final outcomes. Nevertheless, the realization that pro-inflammatory cytokines can also be immunoregulatory offers a new perspective in fully understanding the pathogenesis of autoimmune diseases and in designing better therapies for controlling them.

TNF-α gene polymorphisms and expression

Tumor necrosis factor alpha (TNF-α) is a proinflammatory cytokine with an important role in the pathogenesis of several diseases. Its encoding gene is located in the short arm of chromosome 6 in the major histocompatibility complex class III region. Most of the TNF-α gene polymorphisms are located in its promoter region and they are thought to affect the susceptibility and/or severity of different human diseases. This review summarizes the data related to the association between TNF-α gene and its receptor polymorphisms, and the development of autoimmune diseases. Among these polymorphisms the -308G/A TNF-α promotor polymorphism has been associated several times with the the development of autoimmune diseases, however some discrepant results have been recorded. The other TNF-α gene polymorphisms had little or no association with autoimmune diseases. Current results about the molecules controlling TNF-α expression are also presented. The discrepancy between different records could be related partly to either the differences in the ethnic origin or number of the studied individuals, or the abundance and activation of other molecules that interact with the TNF-α promotor region or other elements.

Role of tumor necrosis factor alpha in the pathogenesis of atrial fibrillation: A novel potential therapeutic target?

Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice and a major cause of morbidity and mortality. Although the fundamental mechanisms underlying AF remain incompletely understood, atrial remodeling, including structural, electrical, contractile, and autonomic remodeling, has been demonstrated to contribute to the substrate for AF maintenance. Accumulating evidence shows that tumor necrosis factor alpha (TNF-α) plays exceedingly important roles in atrial remodeling. This article reviews recent advances in the roles of TNF-α in the pathogenesis of AF, elucidates the related mechanisms, and exploits its potential usefulness as a novel therapeutic target.

Expression of TNFα membrane-bound receptors in the peripheral blood mononuclear cells (PMBC) in rheumatoid arthritis patients

OBJECTIVE

To investigate the expression of TNFα membrane-bound receptors: the percentage of cells expressing these receptors and the number of molecules expressed on different immune cell subsets, and to evaluate serum concentrations of soluble TNFα and its receptors (sTNFRI and sTNFRII) in patients with rheumatoid arthritis in acute stage and after response to treatment compared to healthy donors.

METHODS

The objects of the study are peripheral blood mononuclear cells (PBMC) of healthy donors (n=150) and RA patients (n=40) subjected to hospital treatment with either biological agents (Rituximab) or glucocorticosteroids (methylprednisolone). To determine PBMC phenotype antibodies anti-hCD3-APC, anti-hCD19 PECy7, anti-hCD14 FITC (eBioscience), as well as anti-hTNFRI-PE and anti-hTNFRII-PE (R&D Systems) were used. To determine receptor number on the cells Quantibrite PE Beads (BD) were used.

RESULTS

Cells obtained from patients who responded to therapy and achieved disease remission exhibited either an increase in the percentage of TNFRI+ cells or elevated expression density of this receptor type.

CONCLUSION

Subsets of immunocompetent cells from RA patients show variation in the percentage of membrane-bound receptor positive cells and receptor expression density, which influences the development and progression of the pathological processes in RA. Response to therapy and achievement of disease remission are associated with an increase of TNFRI expression.

Associations between functional TNFR2 196 M/R polymorphisms and susceptibility to rheumatoid arthritis: a meta-analysis

Several studies have examined the effects of tumor necrosis factor receptor (TNFR) 1 +38 A/G and TNFR2 196 M/R polymorphisms on susceptibility to RA and have reported conflicting results. The purpose of this study was to examine whether the TNFR1 +38 A/G and TNFR2 196 M/R polymorphisms are associated with RA susceptibility. We performed a literature search using the Medical Literature Analysis and Retrieval System Online and Embase citation indices, and conducted a meta-analysis to examine the association between the TNFR1 +38 A/G and TNFR2 196 M/R polymorphisms and RA. Our meta-analysis included a total of 13 studies from 11 articles, consisting of 11 studies of the TNFR2 polymorphism (2,092 cases and 1,483 controls), and two studies of the TNFR1 polymorphism (672 cases and 288 controls). The meta-analysis revealed a significant association between the TNFR2 196 RR genotype and RA risk (OR 1.737, 95 % CI 1.275-2.367, P = 4.6 × 10(-5)). Stratification by ethnicity indicated an association between the TNFR2 196 RR genotype and RA in Europeans (OR 2.054, 95 % CI 1.305-3.232, P = 0.002), but not in East Asians (OR 1.596, 95 % CI 0.642-3.971, P = 0.314). Analysis using a homozygote contrast model showed the same pattern for the TNFR2 196 RR genotype in a European and East Asian population. However, no association was found between the TNFR1 +36 A/G polymorphism and RA in a European population. Our meta-analysis demonstrated that the functional TNFR2 196 M/R polymorphism is associated with susceptibility to RA in the European population.

TNF Receptor 2 and Disease: Autoimmunity and Regenerative Medicine

The regulatory cytokine tumor necrosis factor (TNF) exerts its effects through two receptors: TNFR1 and TNFR2. Defects in TNFR2 signaling are evident in a variety of autoimmune diseases. One new treatment strategy for autoimmune disease is selective destruction of autoreactive T cells by administration of TNF, TNF inducers, or TNFR2 agonism. A related strategy is to rely on TNFR2 agonism to induce T-regulatory cells (T_regs) that suppress cytotoxic T cells. Targeting TNFR2 as a treatment strategy is likely superior to TNFR1 because of its more limited cellular distribution on T cells, subsets of neurons, and a few other cell types, whereas TNFR1 is expressed throughout the body. This review focuses on TNFR2 expression, structure, and signaling; TNFR2 signaling in autoimmune disease; treatment strategies targeting TNFR2 in autoimmunity; and the potential for TNFR2 to facilitate end organ regeneration.

The methionine 196 arginine polymorphism of the TNF receptor 2 gene (TNFRSF1B) is not associated with worse outcomes in heart failure

Tumor necrosis factor α (TNFα) may contribute to the pathologic process of congestive heart failure (CHF). TNFα signaling occurs through two receptors; TNFR1 (TNFRSF1A) and TNFRII (TNFRSF1B). In humans a single nucleotide polymorphism (rs1061622 in TNFRSF1B exon 6; T587G) encodes two different amino acids (M196R) in the transmembrane region. The 587G allele is associated with greater severity and/or prevalence of some inflammatory diseases, but its role in CHF in unknown. This study sought to test the hypothesis that the 587G allele is associated with a worse outcome or more severe phenotype in CHF. Peripheral blood DNA was isolated and genotyped from 379 heart failure patients enrolled in a genetic outcome study (GRACE); (44.7% ischemic, 70.4% male, 8.5% black race, age 55.6 ± 11.7 yr (SD), LVEF 24.5 ± 8.3%, NYHA 2.53 ± 0.64). Genotyping was performed by PCR-RFLP. Cardiac function was assessed from medical records at study entry. The distribution of genotypes in this population was 54% T/T, 38.4% G/T and 7.7% G/G. Mean LV ejection fraction (T/T 24.4 ± 8.2, T/G 25.0 ± 8.4, G/G 23.3 ± 8.6, n=352, p=ns) and LV end-diastolic dimensions (T/T 6.57 ± 0.93, T/G 6.53 ± 1.0, G/G 6.57 ± 0.78, n=211, p=ns) were comparable in all groups. Transplant-free survival (median 23 months (range 1-62 months) did not vary by genotype (p=0.95). A lack of effect (p=0.74) on transplant-free survival was also observed in a subset of patients with ischemic heart failure (n=169). The TNFRSF1B 587G allele is not associated with the severity of heart failure phenotype or clinical outcomes in patients with chronic CHF.

Signal transduction by tumor necrosis factor receptors

Tumor necrosis factor (TNF) is a key mediator in the inflammatory response which is implicated in the onset of a number of diseases. Research on TNF led to the characterization of the largest family of cytokines known until now, the TNF superfamily, which exert their biological effects through the interaction with transmembrane receptors of the TNFR superfamily. TNF itself exerts its biological effects interacting with two different receptors: TNFR1 and TNFR2. TNFR1 presents a death domain on its intracellular region. In contrast to TNFR1, TNFR2 does not have a death domain. Activation of TNFR1 implies the consecutive formation of two different TNF receptor signalling complexes. Complex I controls the expression of antiapoptotic proteins that prevent the triggering of cell death processes, whereas Complex II triggers cell death processes. TNFR2 only signals for antiapoptotic reactions. However, recent evidence indicates that TNFR2 also signals to induce TRAF2 degradation. TRAF2 is a key mediator in signal transduction of both TNFR1 and TNFR2. Thus, this novel signalling pathway has two important implications: on one hand, it represents an auto regulatory loop for TNFR2; on the other hand, when this signal is triggered TNFR1 activity is modified so that antiapoptotic pathways are inhibited and apoptotic reactions are enhanced.

Tumor necrosis factor-alpha and the roles it plays in homeostatic and degenerative processes within the central nervous system

Tumor Necrosis Factor-alpha (TNF-α) is a prototypic pro-inflammatory cytokine involved in the innate immune response. TNF-α ligation and downstream signaling with one of its cognate receptors, TNF-RI or TNF-RII, modulates fundamental processes in the brain including synapse formation and regulation, neurogenesis, regeneration, and general maintenance of the central nervous system (CNS). During states of chronic neuroinflammation, extensive experimental evidence implicates TNF-α as a key mediator in disease progression, gliosis, demyelination, inflammation, blood-brain-barrier deterioration, and cell death. This review explores the complex roles of TNF-α in the CNS under normal physiologic conditions and during neurodegeneration. We focus our discussion on Multiple Sclerosis, Parkinson's disease, and Alzheimer's disease, relaying the outcomes of preclinical and clinical testing of TNF-α directed therapeutic strategies, and arguing that despite the wealth of functions attributed to this central cytokine, surprisingly little is known about the cell type- and stage-specific roles of TNF-α in these debilitating disorders.

Lack of association between tumour necrosis factor receptor types 1 and 2 gene polymorphism and severe acute alcoholic hepatitis

BACKGROUND/AIMS

Tumour necrosis factor-alpha (TNF-alpha) is involved in the physiopathology of severe acute alcoholic hepatitis (AAH) binding with TNF receptor types TNFR1 and TNFR2, whose serum concentrations are elevated. We studied the role of TNFR1 and TNFR2 gene polymorphism in AAH patients.

METHODS

One hundred and ninety-two patients (58 AAH with Maddrey score >or=32, 44 non-AAH cirrhoses, 90 healthy individuals) were genotyped for A36G TNFR1 and T676G TNFR2 using polymerase chain reaction-restriction fragment length polymorphism technique. Serum sTNFR1 and sTNFR2 were assayed.

RESULTS

The AAH and two control groups did not differ for genotype distribution. In three groups, A (36 TNFR1) and T (676 TNFR2) allelic frequencies were similar, at 0.47, 0.47, 0.44 and 0.78, 0.81, 0.80, respectively. The 36 TNFR1, 676 TFNR2 genotypes did not influence on prognostic scores (Maddrey, Child-Pugh), nor in response to corticosteroids or 6-month survival. sTNFR1 levels were higher in AAH than healthy group (3.07+/-1.14 vs. 1.17+/-0.27 ng/ml, P<0.001) and sTNFR2 levels were higher in AAH than cirrhosis (3.6+/-1.02 vs. 3.1+/-1.03, P<0.05) and healthy groups (3.6+/-1.02 vs. 1.91+/-0.54, P<0.001). However, sTNFR1 and sTNFR2 levels did not vary significantly according to genotypes.

CONCLUSION

These results did not support an association between 36 TNFR1, 676 TNFR2 gene polymorphisms and AAH.

TNF receptor 2 pathway: drug target for autoimmune diseases

Although drug development has advanced for autoimmune diseases, many current therapies are hampered by adverse effects and the frequent destruction or inactivation of healthy cells in addition to pathological cells. Targeted autoimmune therapies capable of eradicating the rare autoreactive immune cells that are responsible for the attack on the body's own cells are yet to be identified. This Review presents a new emerging approach aimed at selectively destroying autoreactive immune cells by specific activation of tumour necrosis factor receptor 2 (TNFR2), which is found on autoreactive and normal T lymphocytes, with the potential of avoiding or reducing the toxicity observed with existing therapies.

Tumor necrosis factor receptor superfamily, member 1B haplotypes increase or decrease the risk of inflammatory bowel diseases in a New Zealand caucasian population

Inflammatory bowel diseases (IBDs) comprising Crohn disease (CD) and ulcerative colitis (UC) are chronic inflammatory conditions with polygenic susceptibility. Interactions between TNF-alpha and TNF-alpha receptor play a fundamental role in inflammatory response. This study investigates the role that selected single nucleotide polymorphisms (SNPs) and haplotypes in the TNF-alpha receptor (TNSFRSF1B) gene play in the risk of IBD in a New Zealand Caucasian population. DNA samples from 388 CD, 405 UC, 27 indeterminate colitis patients, and 293 randomly selected controls, from Canterbury, New Zealand were screened for 3 common SNPs in TNSFRSF1B: rs1061622 (c.676T > C), rs1061624 (c.*1663A > G), and rs3397 (c.*1690T > C), using TaqMan technologies. Carrying the rs1061624 variant decreased the risk of UC in the left colon (OR 0.73, 95% CI = 0.54–1.00) and of being a smoker at diagnosis (OR 0.62; 95% CI = 0.40–0.96). Carrying the rs3397 variant decreased the risk of penetrating CD (OR 0.62, 95% CI = 0.40–0.95). Three marker haplotype analyses revealed highly significant differences between CD patients and control subjects (χ² = 29.9, df = 7, P = .0001) and UC cases and controls (χ² = 46.3, df = 7, P < .0001). We conclude that carrying a 3-marker haplotype in the TNSFRSF1B gene may increase (e.g., haplotype of GGC was 2.9-fold more in the CD or UCpatients) or decrease (e.g., TGT was 0.47-fold less in UC patients) the risk of IBD in a New Zealand Caucasian population.

Contribution of PTPN22 1858T, TNFRII 196R and HLA-shared epitope alleles with rheumatoid factor and anti-citrullinated protein antibodies to very early rheumatoid arthritis diagnosis

OBJECTIVES

To evaluate the predictive value of TNFRII 196R, PTPN22 1858T and HLA-shared epitope (SE) alleles, RFs and anti-citrullinated protein antibodies (ACPAs) for RA diagnosis in a cohort of patients with very early arthritis.

METHODS

We followed up 284 patients who had swelling of at least two joints that had persisted for longer than 4 weeks but had been evolving for <6 months. At 2 yrs, patients were classified as having RA or non-RA rheumatic diseases according to the ACR criteria. Patients were genotyped with respect to TNFRII 196M/R and PTPN22 1858C/T polymorphisms and HLA-SE. The presence of IgA, IgG and IgM RF isotypes and ACPA was sought in sera collected at disease onset.

RESULTS

HLA-SE alleles alone, concomitant presence of TNFRII 196R and PTPN22 1858T alleles, IgA, IgG and IgM RF alone and ACPA were found to be significantly associated with RA diagnosis. Using logistic regression analysis, the concomitant presence of RF and ACPA at disease onset was the best association to predict RA diagnosis. In patients (n = 34) who did not fulfil the ACR criteria for RA at inclusion but who progressed to ACR positivity, the study of the genetic risk markers did not contribute to predict RA diagnosis at 2 yrs.

CONCLUSIONS

PTPN22 1858T, TNFRII 196R and HLA-SE alleles do not improve the predictive value of RF and ACPA for RA diagnosis in our cohort, and do not contribute to an earlier diagnosis in undifferentiated patients initially negative for RF and ACPA.

Recent advances in the genetics of autoimmune diseases

Autoimmune diseases in general are complex genetic diseases where genes and environment interact in unknown ways. In recent years technologies have advanced our knowledge and new genes are being identified very rapidly. We can expect that most genes of major importance for the various autoimmune diseases will be discovered in the coming 5 years. The real challenge comes when we try to understand the mechanisms through which these genes confer disease susceptibility and how the interaction with environment takes place such that clinical expression of the disease results.

Systemic inflammation in COPD: is genetic susceptibility a key factor?

COPD is a multicomponent disease characterized by abnormal inflammatory response of the lungs to noxious particles that is accompanied by systemic effects like weight loss, muscle wasting, reduced functional capacity and impaired health status. A persistent low-grade systemic inflammatory response reflected by enhanced levels of acute phase proteins like C-reactive protein (CRP) and pro-inflammatory cytokines such as tumor necrosis factor (TNF)-alpha, is present in part of the COPD population. The production of inflammatory proteins is partly genetically determined. Several studies have shown that polymorphisms within genes coding for these inflammatory mediators may modulate systemic inflammatory responses. Among all of these genes, the TNF family (TNF-alpha, lymphotoxin (LT)-alph and their receptors TNF-R55 and TNF-R75), interleukin (IL)-6 and CRP gene polymorphisms are the most prominent candidates. However, large carefully designed studies in well-characterized COPD cohorts are required to unravel the exact role of genetic background in the systemic component of this disease.

A functional M196R polymorphism of tumour necrosis factor receptor type 2 is associated with systemic lupus erythematosus: a case-control study and a meta-analysis

OBJECTIVES

To perform a case-control study of a functional M196R polymorphism of tumour necrosis factor receptor type 2 (TNF-RII) in a Japanese population and a meta-analysis of all published reports on the polymorphism to investigate the association of the M196R polymorphism of TNF-RII with systemic lupus erythematosus (SLE).

METHODS

The functional M196R polymorphism of TNF-RII was genotyped by using polymerase chain reaction combined with the subsequent single-strand conformation polymorphism (PCR-SSCP) analysis for screening, followed by nucleotide sequencing for confirmation. A total of 331 patients and 359 controls were subjected to a case-control study. A meta-analysis of the available case-control studies including all published data as well as our own data was performed to investigate the association of the functional M196R polymorphism of TNF-RII with SLE.

RESULTS

Our case-control study did not show any significant association of a functional M196R polymorphism of TNF-RII with SLE, although there was a trend towards association. A meta-analysis of seven case-control studies in eight different ethnic populations including our own showed that 196M/R and 196R/R genotypes combined was significantly associated with an increased risk of SLE (odds ratio (OR) 1.29, 95% confidence interval (CI) 1.04 to 1.60; p = 0.02). Stratification by ethnicity showed a more significant association in Asians, including Japanese, Korean and Vietnamese (OR 1.40, 95% CI 1.10 to 1.78; p = 0.006). The effect of the 196R allele on SLE was not clear in Caucasians.

CONCLUSIONS

The 196R allele of the functional M196R polymorphism of TNF-RII is a risk factor for SLE, especially in the Asian population.

Replication of putative candidate-gene associations with rheumatoid arthritis in >4,000 samples from North America and Sweden: association of susceptibility with PTPN22, CTLA4, and PADI4

Candidate-gene association studies in rheumatoid arthritis (RA) have lead to encouraging yet apparently inconsistent results. One explanation for the inconsistency is insufficient power to detect modest effects in the context of a low prior probability of a true effect. To overcome this limitation, we selected alleles with an increased probability of a disease association, on the basis of a review of the literature on RA and other autoimmune diseases, and tested them for association with RA susceptibility in a sample collection powered to detect modest genetic effects. We tested 17 alleles from 14 genes in 2,370 RA cases and 1,757 controls from the North American Rheumatoid Arthritis Consortium (NARAC) and the Swedish Epidemiological Investigation of Rheumatoid Arthritis (EIRA) collections. We found strong evidence of an association of PTPN22 with the development of anti-citrulline antibody-positive RA (odds ratio [OR] 1.49; P=.00002), using previously untested EIRA samples. We provide support for an association of CTLA4 (CT60 allele, OR 1.23; P=.001) and PADI4 (PADI4_94, OR 1.24; P=.001) with the development of RA, but only in the NARAC cohort. The CTLA4 association is stronger in patients with RA from both cohorts who are seropositive for anti-citrulline antibodies (P=.0006). Exploration of our data set with clinically relevant subsets of RA reveals that PTPN22 is associated with an earlier age at disease onset (P=.004) and that PTPN22 has a stronger effect in males than in females (P=.03). A meta-analysis failed to demonstrate an association of the remaining alleles with RA susceptibility, suggesting that the previously published associations may represent false-positive results. Given the strong statistical power to replicate a true-positive association in this study, our results provide support for PTPN22, CTLA4, and PADI4 as RA susceptibility genes and demonstrate novel associations with clinically relevant subsets of RA.

Genetic basis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a multifactorial disease due to a combination of genetic and environmental factors. Identification of the genetic factors involved in the pathogenesis of RA should open up avenues for developing radical treatment strategies directed at the cause of the disease. The Association de Recherche sur la Polyarthrite (ARP) supports research in this field, in which our group has been involved since 1993. Thanks to this support, considerable progress has been made. Several combinations of susceptibility alleles of various genes are probably involved in the development of RA. Although HLA-DRB1 is the main RA gene, it accounts for only part of the familial risk for RA. HLA-DRB1 alleles are neither necessary nor sufficient to cause the development of RA in a given individual. Several genome scans conducted in populations from France, Japan, North America and UK have confirmed the role of the HLA region and suggested several other susceptibility loci. Association studies support a role for several genes, including TNFR2, PADI4, SLC22A4, RUNX1, and PTPN22. However, the imperfect matching of cases and controls requires that confirmation of these results be obtained. To confirm that a gene confers susceptibility to RA, the association must be replicated in several independent studies and, more importantly, evidence of genetic linkage must be obtained in family studies. The identification of genetic factors conferring susceptibility to RA will open up new avenues toward radical treatments for RA and may help to optimize the diagnostic, prognostic, and pharmacogenetic management of today's patients with RA.

Haplotype analysis of tumour necrosis factor receptor genes in 1p36: no evidence for association with systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease with partially understood aetiology. The 1p36 region has been previously linked with SLE and harbours tumour necrosis factor receptor (TNFR) genes. Functional and genetic data implicate their gene products in SLE and other autoimmune diseases. In all, single-nucleotide polymorphisms (SNPs) across TNFRSF14 (HVEM), and 43 SNPs across the TNFRSF8 (CD30) and TNFRSF1B (CD120B) locus were investigated for linkage disequilibrium (LD) and haplotype analysis in European-Caucasians. Strong LD was observed across HVEM and CD120B, and little LD and recombination across CD30. We also examined the association of SNPs and haplotypes in HVEM, CD30 and CD120B with SLE in European-Caucasians. There was no evidence of association for these genes in 456 European-Caucasian families with SLE from UK. Haplotype tagging SNPs are made known across areas of strong LD, which will facilitate analysis for susceptibility in other diseases.

Genome scan meta-analysis of rheumatoid arthritis

OBJECTIVE

Genome scans for rheumatoid arthritis (RA) have yielded inconsistent results. The absence of replication of linkage might be due to lack of power of individual studies. We performed a genome scan meta-analysis of published data to increase statistical power and to assess evidence for linkage of RA across genome scan studies.

METHODS

Four RA whole-genome scans containing 767 families with 964 sibling pairs were included for the genome scan meta-analysis (GSMA). The GSMA method was applied to pool the results obtained from four genome scans. For each study, 120 genomic bins of approximately 30 centimorgans were defined and ranked according to maximum evidence for linkage within each bin. Bin ranks were weighted and summed across all studies. The summed rank for each bin was assessed empirically for significance using permutation methods.

RESULTS

A total of nine bins lay above the 95% confidence level (P=0.05) and four bins were above the 99% confidence level (P=0.01) in the RA GSMA, suggesting that these bins contain RA-linked loci: bins 6.2, 6.4, 8.1, 18.3, 12.3, 12.2, 1.5, 6.3 and 16.2. The strongest evidence for linkage occurred on chromosome 6p22.3-6p21.1 (bin 6.2), containing the HLA region (P(sumrnk)=0.0000008).

CONCLUSION

This RA GSMA confirmed the evidence for HLA loci as the greatest susceptibility factor to RA and showed evidence for linkage at non-HLA loci, such as chromosomes 1p, 6, 8p, 12, 16 and 18q, across studies. These data may provide a basis to carry out targeted linkage and candidate gene studies, particularly in the regions.

Polymorphism in the tumour necrosis factor receptor II gene is associated with circulating levels of soluble tumour necrosis factor receptors in rheumatoid arthritis

Levels of soluble tumour necrosis factor receptors (sTNFRs) are elevated in the circulation of patients with rheumatoid arthritis (RA). Although these receptors can act as natural inhibitors of tumour necrosis factor-alpha, levels of sTNFRs in RA appear to be insufficient to prevent tumour necrosis factor-alpha induced inflammation. The factors that regulate circulating levels of sTNFRs are unclear, but polymorphisms in the tumour necrosis factor receptor genes may play a role. We investigated the relationship between polymorphisms in the tumour necrosis factor receptor I (TNF-RI) and II (TNF-RII) genes and levels of sTNFRs in two groups of Caucasian RA patients: one with early (disease duration < or = 2 years; n = 103) and one with established disease (disease duration > or = 5 years; n = 151). PCR restriction fragment length polymorphism analysis was used to genotype patients for the A36G polymorphism in the TNF-RI gene and the T676G polymorphism in TNF-RII. Levels of sTNFRs were measured using ELISA. We also isolated T cells from peripheral blood of 58 patients with established RA with known TNF-R genotypes, and release of sTNFRs into the culture medium was measured in cells incubated with or without phytohaemagglutinin. Serum levels of the two sTNFRs (sTNF-RI and sTNF-RII) were positively correlated in both populations, and the level of each sTNFR was significantly higher in the patients with established disease (P < 0.0001). Multiple regression analyses corrected for age, sex and disease duration revealed a significant trend toward decreasing sTNF-RI and sTNF-RII levels across the TNF-RII genotypes (TT > TG > GG) of patients with established disease (P for trend = 0.01 and P for trend = 0.03, respectively). A similar nonsignificant trend was seen for early disease. No relationship with the TNF-RI A36G polymorphism was observed. sTNFRs released by isolated T cells exhibited a similar trend toward decreasing levels according to TNF-RII genotype, although only the association with levels of sTNF-RII was significant. Strong correlations were found between levels of circulating sTNFRs and levels released by T cells in vitro. Our data indicate that the T676G polymorphism in TNF-RII is associated with levels of sTNFRs released from peripheral blood T cells, and with circulating levels of sTNFR in patients with RA.

Rheumatoid arthritis seropositive for the rheumatoid factor is linked to the protein tyrosine phosphatase nonreceptor 22-620W allele

The protein tyrosine phosphatase nonreceptor type 22 (PTPN22) gene encodes for lymphoid tyrosine phosphatase LYP, involved in the negative regulation of early T-cell activation. An association has recently been reported between the PTPN22-620W functional allele and rheumatoid factor-positive (RF+) rheumatoid arthritis (RA), among other autoimmune diseases. Expected linkage proof for consistency cannot be definitely produced by an affected sib-pair (ASP) analysis. Our aim was therefore to search for linkage evidence with the transmission disequilibrium test. DNA from the French Caucasian population was available for two samples of 100 families with one RA patient and both parents, and for 88 RA index cases from RA ASP families. Genotyping was carried out by PCR-restriction fragment length polymorphism. The analysis was performed using the transmission disequilibrium test, genotype relative risk and ASP-based analysis. The transmission disequilibrium test of the PTPN22-620W allele revealed linkage and association for RF+ RA (61% of transmission, P = 0.037). The genotype relative risk showed the risk allele in 34% of RF+ RA patients and in 24% of controls derived from nontransmitted parental chromosomes (P = 0.047, odds ratio = 1.69, 95% confidence interval = 1.03-2.78). The ASP investigation showed no enriched risk allele in RA multiplex families, resulting in a lack of power of ASP analysis, explaining the published negative results. This study is the first to show linkage of PTPN22 to RF+ RA, consistent with PTPN22 as a new RA gene.

Association between the TNFRII 196R allele and diagnosis of rheumatoid arthritis

Tumour necrosis factor (TNF)-α plays a key role in the pathogenesis of rheumatoid arthritis (RA). It binds to two receptors, namely TNF receptor (TNFR)I and TNFRII. Several studies have suggested an association between TNFRII 196R/R genotype and RA. The objective of the present study was to evaluate the predictive value of the TNFRII 196R allele for RA diagnosis and prognosis in a cohort of patients with very early arthritis. We followed up a total of 278 patients recruited from the community, who had swelling of at least two joints that had persisted for longer than 4 weeks but had been evolving for less than 6 months, and who had not received disease-modifying antirheumatic drugs or steroid therapy. At 2 years, patients were classified according to the American College of Rheumatology criteria. All patients were genotyped with respect to TNFRII 196M/R polymorphism. Radiographs of hands and feet (read according to the modified Sharp method) and the Health Assessment Questionnaire were used to quantify structural and functional severity. The cohort of 278 patients was found to include 156 and 122 RA and non-RA patients, respectively. The TNFRII 196R allele was found to be associated with RA (P = 0.002). However, progression of radiographic severity and Health Assessment Questionnaire scores over 1 year did not differ between carriers of the 196R allele and noncarriers. Our findings suggest that the TNFRII 196R allele may be associated with RA diagnosis but that it does not predict early radiographic progression or functional severity in patients with very early, unclassified arthritis.

New classification of HLA-DRB1 alleles supports the shared epitope hypothesis of rheumatoid arthritis susceptibility

OBJECTIVE

The shared epitope hypothesis was formulated to explain the involvement of HLA-DRB1 in rheumatoid arthritis (RA). However, several studies, which considered only the HLA-DRB1 alleles shown to be associated with RA risk, rejected this hypothesis. In this report, we propose that a different classification of HLA-DRB1 alleles be considered, based on the amino acid sequence at position 70-74.

METHODS

The fit of both HLA-DRB1 classifications was tested in 2 groups of RA patients. All subjects were recruited through the European Consortium on Rheumatoid Arthritis Families, and included 100 patients with isolated RA and 132 patients with at least 1 affected sibling.

RESULTS

The new classification produced risk estimates that fit all of the observed data, i.e., the distribution of the HLA-DRB1 genotype in the 2 patient groups, and the distribution of parental alleles shared by affected sibpairs. The risk of developing RA under this new classification depends on whether the RAA sequence occupies position 72-74 but is modulated by the amino acid at position 71 (K confers the highest risk, R an intermediate risk, A and E a lower risk) and by the amino acid at position 70 (Q or R confers a higher risk than D).

CONCLUSION

A new classification based on amino acid sequence allows us to show that the shared epitope RAA sequence at position 72-74 explains the data, with the risk of developing RA modulated by the amino acids at positions 70 and 71.

Understanding the genetic contribution to rheumatoid arthritis

PURPOSE OF REVIEW

The identification of the genetic variants that mediate the risk for susceptibility and severity of rheumatoid arthritis will allow the development of new drug targets and also increase the ability to predict disease course. Technical and methodologic progress has fueled the advances in this field.

RECENT FINDINGS

The second risk factor for rheumatoid arthritis, the PTPN22 polymorphism, has been identified. This genetic variant regulates the threshold of T cell activation. Intriguingly, this variant is a risk factor for diabetes as well. Moreover, it has been shown that multiple genetic variants in one pathway (both in a transcription factor, RUNX-1, as in the transcription factor binding site of RUNX1 in the SLC22A4 gene) can each confer very small risks but by gene-gene interactions can confer a ninefold risk for rheumatoid arthritis. These genetic risk factors have been found to confer risk for multiple autoimmune diseases. Phenotype-genotype interactions were described by the enhanced prevalence of a rheumatoid arthritis-specific autoantibody (anti-cyclic citrullinated peptide antibodies) in rheumatoid arthritis patients that harbor the rheumatoid arthritis-associated human leukocyte antigen class II genes, the shared epitope alleles. An environmental factor, smoking was demonstrated to confer risk for rheumatoid arthritis, especially in patients positive for both shared epitope and rheumatoid arthritis-specific anti-cyclic citrullinated peptide antibodies.

SUMMARY

Two new pathways, T cell receptor signaling and a hematopoietic-specific signal transduction pathway, have been discovered that allow future pharmacologic interventions. The description of the new genetic risk factors and the interaction with environmental triggers as well as phenotypic features are gradually expanding the ability to predict disease susceptibility and course.

The Met-196 -> Arg variation of human tumor necrosis factor receptor 2 (TNFR2) affects TNF-alpha-induced apoptosis by impaired NF-kappaB signaling and target gene expression

Tumor necrosis factor-alpha (TNF-alpha)-induced signaling is pivotally involved in the pathogenesis of chronic inflammatory diseases. A polymorphism in the TNF receptor 2 (TNFR2) gene resulting in a juxtamembrane inversion from methionine (TNFR2(196MET)) to arginine (TNFR2(196ARG)) has been genetically associated with an increased risk for systemic lupus erythematosus and familial rheumatoid arthritis. Albeit the mutation does not affect the TNF binding kinetics of TNFR2, the present study provides evidence that the mutation results in a significantly lower capability to induce TNFR2-mediated NF-kappaB activation. Pretriggering of TNFR2 with a receptor-specific mutein leads to an enhancement of TNFR1-induced apoptosis, which is further increased in cells carrying the TNFR2(196ARG) variant. A diminished induction of NF-kappaB-dependent target genes conveying either anti-apoptotic or pro-inflammatory functions, such as cIAP1, TRAF1, IL-6, or IL-8 is observed. The mutated form TNFR2(196ARG) shows a reduction of inducible TRAF2 recruitment upon TNF-alpha stimulation. The findings suggest a common molecular mechanism for the involvement of the TNFR2(196ARG) variant in the etiopathogenesis of different chronic inflammatory disorders.

Genetic variants in the tumor necrosis factor receptor II gene in patients with multiple sclerosis

Common genetic variants have been shown to influence disease susceptibility, disease course, or both in multiple sclerosis (MS). Several studies have suggested a role for tumor necrosis factor-alpha (TNF-alpha) in the pathogenesis of MS. Recently, it has been reported that the TNF receptor (TNFR) II plays an essential role in the pathology and progression of experimental autoimmune encephalomyelitis, an animal model of MS. To investigate whether TNFR II polymorphisms influence susceptibility and/or clinical progression of MS, genomic DNA of 321 samples of the Austrian Genetics in MS study group and DNA of 174 platelet donors, who served as healthy controls, were genotyped for five polymorphic sites in the TNFR II gene: exon 6 nucleotide (nt) 676*T-->G, exon 6 nt 783*G-->A (both are associated with non-conserved amino acid substitution), exon 10 nt 1663*G-->A, exon 10 nt 1668*T-->G, and exon 10 nt 1690*T-->C (all of which are located in the 3' non-coding region of the gene). We found a significant association between exon 10 nt 1668*T-->G polymorphism and susceptibility to MS. The other investigated nucleotide substitutions were not associated with susceptibility to or clinical parameters in MS.

Dense genome-wide linkage analysis of rheumatoid arthritis, including covariates

OBJECTIVE

Rheumatoid arthritis (RA) is a heterogeneous disease that exhibits a complex genetic component. Previous RA genome scans confirmed the involvement of the HLA region and generated data on suggestive signals at non-HLA regions, albeit with few overlaps in findings between studies. The present study was undertaken to detect potential RA gene regions and to estimate the number of true RA gene regions, taking into account the heterogeneity of RA, through performance of a dense genome scan.

METHODS

In a study of 88 French Caucasian families (105 RA sibpairs), 1,088 microsatellite markers were genotyped (3.3-cM genome scan), and a multipoint model-free linkage analysis was performed. The statistical assessment of the results relied on 10,000 computer simulations. A covariate-based multipoint model-free linkage analysis was performed on the locations of regions with suggestive evidence for linkage.

RESULTS

Involvement of the HLA region was strongly confirmed (P = 6 x 10(-5)), and 19 non-HLA regions showed suggestive evidence for linkage (P < 0.05); 9 of these overlapped with regions suggested in other published RA genome scans. A routine 12-cM genome scan with the same families would have detected only 7 of the 19 regions, including only 4 of the 9 overlapping regions. From the 10,000 computer simulations, we estimated that 8 +/- 4 regions (mean +/- SD) were true-positives. RA covariate-based analysis provided additional linkage evidence for 3 regions, with age at disease onset, erosions, and HLA-DRB1 shared epitope as covariates.

CONCLUSION

The results of this study provide evidence of 19 non-HLA RA gene regions, with an estimate of 8 +/- 4 as true-positives, and provide additional evidence for 3 regions from covariate-based analysis.

Tumour necrosis factor-alpha receptor 1 and 2 polymorphisms in inflammatory bowel disease and their association with response to infliximab

BACKGROUND

The role of tumour necrosis factor-alpha in the pathogenesis of inflammatory bowel disorders is well-known and is underscored by the effectiveness of antitumour necrosis factor-alpha treatment. Tumour necrosis factor-alpha exerts its effect by binding TNFR1 and TNFR2, which genes map to inflammatory bowel disorders susceptibility loci.

AIMS AND METHODS

Since TNFR1 and TNFR2 are good candidate genes for inflammatory bowel disorders, we studied the functional TNFR2T587G and the TNFR1A36G mutation in 344 Crohn's disease and 152 ulcerative colitis patients and investigated the relation with disease phenotypes. An association with response to infliximab was evaluated in 166 Crohn's disease patients.

RESULTS

The TNFR2 587G allele was more frequent in ulcerative colitis compared with controls (P = 0.03). Both single nucleotide polymorphisms were negatively associated with smoking at diagnosis in Crohn's disease (TNFR1A36G odds ratio: 0.614, 95% confidence interval: 0.452, 0.99 and TNFR2T587G odds ratio: 0.572, 95% confidence interval: 0.820, 0.875). There was a positive association between pancolitis and the TNFR1A36G polymorphism in ulcerative colitis (odds ratio: 5.341, 95% confidence interval: 1.484, 19.39). The biological response to infliximab was lower in patients carrying TNFR1 36G (odds ratio: 0.47, 95% confidence interval: 0.234, 0.946).

CONCLUSION

The TNFR2 587G allele was more frequent in ulcerative colitis. Both single nucleotide polymorphisms were negatively associated with smoking in Crohn's disease. A relation between TNFR1A36G and pancolitis was found in ulcerative colitis. There was no clear effect of the polymorphisms on infliximab response although, the TNFR1 minor was associated with a lower response to infliximab.

Tumor necrosis factor receptor II gene polymorphism and severity of rheumatoid arthritis

OBJECTIVE

The gene encoding tumor necrosis factor receptor type II (TNFRII) is a strong candidate in the pathogenesis of rheumatoid arthritis (RA). An association between a single-nucleotide polymorphism (196M/R) in exon 6 of the TNFRII gene and familial RA was recently reported. The present study was undertaken to test the hypothesis that there is an association between this polymorphism and the severity of RA.

METHODS

One hundred two white patients with early RA were included in this prospective study. The French version of the Health Assessment Questionnaire (F-HAQ) and a radiographic damage score (modified Sharp/van der Heijde method) were used to quantify the functional and structural severity of RA at baseline and after 4 years of followup. TNFRII 196M/R polymorphism genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Among the 102 patients with RA, 63 (61.8%) were homozygous for the 196M allele, 36 (35.3%) were heterozygous for alleles 196M and 196R, and 3 (2.9%) were homozygous for the 196R allele. At baseline, the median radiographic and F-HAQ scores did not differ between RA patients who carried the 196R allele and those who did not. After 4 years of followup, the F-HAQ score was higher in RA patients carrying the 196R allele (median 1 [interquartile range (IQR) 0.125, 1.375]) than in noncarriers (0.375 [IQR 0, 1]) (P = 0.02), while the median radiographic score did not differ between RA patients who carried the 196R allele and those who did not.

CONCLUSION

The results of the present study support the hypothesis that there is an association between the TNFRII 196 M/R gene polymorphism and the functional severity of early RA.

ATNFR1genotype with a protective role in familial rheumatoid arthritis

OBJECTIVE

Results of genome scans in rheumatoid arthritis (RA) have suggested that the tumor necrosis factor receptor I (TNFRI) and TNFRII loci (TNFR1 and TNFR2) are susceptibility loci. A TNFR2 polymorphism was found to be associated with familial RA. TNFR1 is mutated in TNFR-associated periodic syndrome (TRAPS). We undertook this study to test the TNFR1 exonic polymorphism closest to the TRAPS mutations site (+36 A/G) for association with RA.

METHODS

DNA samples were available from two groups of the French Caucasian population: 1) 100 families with 1 RA patient and both parents and 2) 86 RA index patients from families with at least 2 siblings with RA (affected sibpairs [ASPs]). The +36 A/G polymorphism of TNFR1 was genotyped by polymerase chain reaction-restriction fragment length polymorphism. The analysis was performed using the transmission disequilibrium test, the genotype relative risk, and a linkage-based test previously described.

RESULTS

A negative association between RA and the +36 A/A genotype, suggested in the first sample (P = 0.084), was demonstrated in the second (ASP RA) sample (odds ratio [OR] 0.465; P = 0.012) and confirmed by the linkage-based test (OR 0.17; P = 0.008). The protective genotype, present in 41% of controls, was less frequent in RA patients: 33% in the first sample, 24% in the ASP RA sample, and 11% in the linkage-derived subgroup. Distribution of both TNFR2 196 R/R and TNFR1 +36 A/A genotypes in the ASP RA sample showed that both suspected genotypes were exclusive.

CONCLUSION

We found evidence for an association between RA and a TNFR1 protective genotype, restricted to familial RA. Distribution of the TNFR2 196 R/R and TNFR1 +36 A/A genotypes in familial RA could suggest an interaction between TNFR1 and TNFR2 in the genetic susceptibility for RA.

Complex genetic predisposition in adult and juvenile rheumatoid arthritis

Background

Rheumatoid arthritis (RA) and juvenile rheumatoid arthritis (JRA) are complex multifactorial diseases caused by environmental influences and an unknown number of predisposing genes. The present study was undertaken in order to investigate association of polymorphisms in candidate genes with RA and JRA in German subjects.

Results

Up to 200 unrelated German RA and JRA patients each and 300–400 healthy controls have been genotyped for HLA-DRB1, TNFa, TNFA -238a/g, TNFA -308a/g, TNFA -857c/t, TNFR1 -609g/t, TNFR1 P12P, TNFR2 del 15bp, IKBL -332a/g, IKBL -132t/a, IKBL C224R, CTLA4 -318c/t, CTLA4 T17A, PTPRC P57P, MIF -173g/c, the MIF and IFNG microsatellites as well as for D17S795, D17S807, D17S1821 by polyacrylamide gel electrophoresis, single-strand conformation polymorphism analysis, restriction fragment length polymorphism analysis or allele specific hybridization. None of the investigated genetic markers is associated with both, RA and JRA, but there are some statistically significant differences between patients and controls that have to be discussed sensibly.

Conclusions

The difficulty in investigating the genetics of complex disorders like RA and JRA may arise from genetic heterogeneity in the clinically defined disease cohorts (and generally limited power of such studies). In addition, several to many genes appear to be involved in the genetic predisposition, each of which exerting only small effects. The number of investigated patients has to be increased to establish the possibility of subdivison of the patients according their clinical symptoms, severity of disease, HLA status and other genetic characteristics.

CARD15 and HLA DRB1 alleles influence susceptibility and disease localization in Crohn's disease

OBJECTIVES

Crohn's disease (CD) is a chronic inflammatory disease of the gut associated with allelic variants of CARD15 and HLA-DRB1 genes. We investigated the prevalence and effects of these variants in a Canadian CD cohort.

METHODS

507 unrelated CD patients were genotyped for the three major CD-associated variants (Arg702Trp, Gly908Arg, and Leu1007fsinsC) and for thirteen HLA-DRB1 alleles.

RESULTS

At least one CARD15 variant was present in 32.5% of the CD patients compared with 20% of controls. The prevalence of CARD15 mutation was similar in both sporadic and familial and Jewish and non-Jewish CD patients. The Gly908Arg variant was significantly higher and the Arg702Trp variant significantly lower in Jewish compared to non-Jewish patients. A positive association between the HLA-DRB1*0103 allele and CD was detected in non-Jewish, familial cases (p = 0.0002), with risk for CD increased by 6.7 fold by the presence of an HLA-DRB1*0103 allele as compared to 1.9 fold and 19 fold by a single or two CARD15 variant alleles, respectively. We show a significant association of ileal involvement with CARD15 variants (OR = 1.8; p = 0.02), HLA-DRB1*0701 (OR = 1.9; p = 0.006) and DRB1*04 (OR = 1.7; p = 0.02) alleles and demonstrate the capacity of combined CARD15 and HLA-DRB1 genotyping to predict ileal disease in CD patients. By contrast, the HLA-DRB1*0103 allele was associated with later age of diagnosis (p = 0.02) and pure colonic disease (p = 0.000013).

CONCLUSIONS

These observations confirm the influence of CARD15 and HLA-DRB1 alleles on both CD susceptibility and site of disease and identify genotyping of these variants as a potential tool for improved diagnosis and risk prediction in CD.

Expression and function of TNF-family proteins and receptors in human osteoblasts

We studied how tumor necrosis-factor (TNF)-family proteins interact with osteoblasts to resolve several controversial points. We measured expression of TNFs, TNF-receptors, and nonsignaling (decoy) TNF receptors in human osteoblasts derived from mesenchymal stem cells and in MG63 human osteosarcoma cells using unamplified mRNA screening, with secondary Western or PCR analysis where indicated, and studied the effects of TNFs on osteoblasts in cell culture. Expression of TNFs and receptors was similar in MG63 cells and osteoblasts. TNF-R1 (p55), TRAIL receptor 1 and 2 (DR4 and 5), and Fas were expressed; RANK was undetectable. TNF-family ligands RANKL, TRAIL, and TNFalpha were expressed, but mRNAs were typically at low levels relative to receptors, suggesting that osteoblastic TNF signals, including RANKL, require specific stimuli. Flow cytometry of MG63 cells confirmed TNFalpha receptors and identified subpopulations with high surface-bound TNFalpha. Decoy receptors expressed included a novel soluble form of TNFRSF25 (formerly DR3 or Apo3), implicated in rheumatoid-arthritis linkage studies, as well as osteoprotegerin, a well-characterized osteoblast protein that binds TRAIL and RANKL, and DcR2, which binds TRAIL. Osteoblast apoptosis was studied using terminal deoxynucleotidyl transferase labeling and annexin V binding. MG63 cells were resistant to apoptosis by exogenous TNFalpha except when grown in media promoting osteoblast-like growth or matrix nodules. However, in media supporting osteoblast-like phenotype, apoptosis was induced by anti-Fas or TNF, in contrast to other studies with human osteoblasts. TRAIL caused cell retraction, supporting functional TRAIL response in cell differentiation, but did not cause apoptosis. We conclude that human osteoblasts have functional receptors for FasL, TNFalpha, TRAIL, but not RANKL, and that osteoblasts are protected by multiple nonsignaling TNF receptors against destruction by TNF-family proteins under conditions favoring cell growth.

Genetics in rheumatoid arthritis

This chapter reviews the latest original research on the genetics of rheumatoid arthritis (RA), with a focus on its relevance for the clinical rheumatologist. The following questions will be dealt with in order to appreciate the recent progress in this field. * Why is a knowledge of genetics useful for an understanding of the pathogenesis of RA? * Is a knowledge of genetic risk factors relevant for day-to-day clinical practice? * What methods are used for identifying genetic risk factors? * Which genetic regions have been identified in susceptibility to RA? * What risk factors have been identified? * What are the future prospects and research agenda?

Gene expression profiling in CD34 cells to identify differences between aplastic anemia patients and healthy volunteers

An immune pathophysiology for acquired aplastic anemia (AA) has been inferred from the responsiveness of the patients to immunosuppressive therapies and experimental laboratory data. To address the transcriptome of hematopoietic cells in AA, we undertook GeneChip analysis of the extremely limited numbers of progenitor and stem cells in the marrow of patients with this disease. We pooled total RNA from highly enriched bone marrow CD34 cells of 36 patients with newly diagnosed AA and 12 healthy volunteers for analysis on oligonucleotide chips. A large number of genes implicated in apoptosis and cell death showed markedly increased expression in AA CD34 cells, and negative proliferation control genes also had increased activity. Conversely, cell cycle progress-enhancing genes showed low expression in AA. Cytokine/chemokine signal transducer genes, stress response genes, and defense/immune response genes were up-regulated, as anticipated from other evidence of the heightened immune activity in AA patients' marrow. In summary, detailed genetic analysis of small numbers of hematopoietic progenitor cells is feasible even in marrow failure states where such cells are present in very small numbers. The gene expression profile of primary human CD34 hematopoietic stem cells from AA was consistent with a stressed, dying, and immunologically activated target cell population. Many of the genes showing differential expression in AA deserve further detailed analysis, including comparison with other marrow failure states and autoimmune disease.

Variations in immune response genes and their associations with multifactorial immune disorders

There are three genetic methods often used for detecting genes contributing to susceptibility or resistance to multifactorial diseases: nonparametric linkage analysis, case-control association analysis, and transmission disequilibrium test. In this review, we present the theoretical basis that the case-control association study has the highest power of detecting disease genes if there is no population stratification between patients and controls. Taking advantage of the high power, we have carried out extensive case-control association analyses of candidate genes for the search of susceptibility genes to rheumatic diseases in the Japanese as well as in some other populations. Several new associations have been disclosed, including those of TNFR2, FCGR2B, and CD19 gene polymorphisms with systemic lupus erythematosus, in addition to some unexpected findings such as the common occurrence of NKG2-C null allele in the healthy population. Genome-wide association studies using single nucleotide polymorphisms (SNPs) or microsatellite polymorphisms have become realistic, and development of new high-throughput and cost-effective SNP typing technologies is urgently needed. At the same time, our observations may indicate that the 'classical' candidate gene approach will remain a strong alternative, even in the age of 'post genome-sequence'.