Genetic variants in the tumor necrosis factor receptor 1 gene in patients with MS

Inflammation and Atherosclerosis: The Role of TNF and TNF Receptors Polymorphisms in Coronary Artery Disease

Inflammation plays an important role in the pathogenesis of atherosclerosis and coronary syndromes; moreover, various lines of evidence suggest that genetic factors contribute significantly to the risk of coronary artery disease (CAD). Through its effects on endothelial function, coagulation, insulin resistance and lipid metabolism, the proinflammatory cytokine TNF could be involved in cardiovascular pathophysiology. The aim of our study is to analyze whether TNF gene promoter (-308 G/A; −857 G/A) and TNF receptor polymorphisms (TNFR1 MspA1 I exon 1 and TNFR2 Nla III exon 6) show involvement in CAD predisposition in a group of Italian patients compared with healthy controls. Genotyping was performed by PCR-RFLP. Consecutive Italian patients with angiographically proven CAD (n= 248) were compared with controls (n=241), matched for age, sex and geographical origins. CAD patients showed a higher frequency of the TNF −308 A allele than healthy controls (p=0.046). After stratification according to risk factors for CAD, our analysis revealed that CAD patients with diabetes (p=0.042) and CAD patients without hypertension (p=0.0495) displayed a higher frequency of the TNF −308 AA genotype compared with healthy controls. Our data stress the inflammatory nature of CAD and show a possible involvement of TNF −308G/A promoter polymorphisms in the predisposition to the development of this disease. The less frequent A allele seems to be a predisposing factor for development of CAD in particular pathological settings associated with the disease itself, such as diabetes.

Late-onset tumor necrosis factor receptor–associated periodic syndrome in multiple sclerosis patients carrying theTNFRSF1A R92Q mutation

OBJECTIVE

Tumor necrosis factor receptor-associated periodic syndrome (TRAPS) is an autosomal-dominantly inherited autoinflammatory disorder caused by mutations in the TNFRSF1A gene. It is characterized by episodes of autoinflammation usually associated with fever, abdominal pain, myalgia, exanthema, arthralgia/arthritis, and ocular involvement. We undertook this study to investigate the prevalence of TRAPS in patients with multiple sclerosis (MS) who reported, in addition to their neurologic symptoms, at least 2 other symptoms compatible with TRAPS.

METHODS

Twenty-five unrelated MS patients were prospectively screened for TNFRSF1A mutations. In addition, blood samples from 365 unrelated MS patients and 407 unrelated Caucasian controls were analyzed to determine the R92Q carrier frequency.

RESULTS

Six of 25 adult MS patients (24%) with symptoms suggestive of TRAPS were found to carry the identical arginine-to-glutamine substitution at amino acid position 92 (R92Q or p.Arg121Gln) encoded by exon 4 of the TNFRSF1A gene. All R92Q heterozygotes had similar symptoms, including arthralgias/arthritis, myalgias, urticarial rash, and severe fatigue, which began before the onset of MS. In 5 of the 6 patients, we could identify family members who had TRAPS symptoms and had inherited the identical mutation. The R92Q exchange was also detected in 17 of 365 unselected MS patients (4.66%) and in 12 of 407 controls (2.95%) (P = 0.112). Three patients were heterozygous carriers of MEFV variants, in 1 patient in combination with the R92Q mutation.

CONCLUSION

Autoinflammatory syndromes and especially late-onset TRAPS should be considered in MS patients who report symptoms such as arthralgias/arthritis, myalgias, urticarial rash, and severe fatigue.

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.

Genetic polymorphisms of apolipoprotein E4 and tumor necrosis factor beta as predisposing factors for increased inflammatory cytokines after cardiopulmonary bypass

OBJECTIVE

Cardiopulmonary bypass induces a rise in cytokines released by activated monocytes. The apolipoprotein E and the tumor necrosis factor beta polymorphisms are risk factors for atherosclerosis. The aim of the study was to investigate whether the genetic variants of apolipoprotein E (APOE*E4) and tumor necrosis factor beta (TNFB*A329G) affect cytokine release after cardiopulmonary bypass.

METHODS

Thirty-eight patients underwent standard coronary artery bypass grafting procedures. Genotyping for APOE*E4 and TNFB*A329G was performed. Concentrations of interleukin 8 and tumor necrosis factor alpha were measured for 48 hours after surgery. Clinical data were collected prospectively.

RESULTS

Fourteen patients (37%) carried the combination non-APOE*E4/wild-type TNFB*A329, 12 patients (32%) showed non-APOE*E4/TNFB*A329G, 9 patients (24%) had APOE*E4/TNFB*A329G, and 3 patients (7%) had APOE*E4/wild-type TNFB*A329. Total amount of tumor necrosis factor alpha was significantly higher in patients carrying the combination APOE*E4/TNFB*A329 than in those carrying non-APOE*E4/wild-type TNFB*A329 (P <.0001). Clinical data were similar except for intubation time and amount of transfusion, which were significantly increased in patients with genetic polymorphisms (P =.022, P =.033).

CONCLUSION

Presence of TNFB*A329G polymorphism in addition to APOE*E4 variant is associated with significantly higher releases of interleukin 8 and tumor necrosis factor alpha, prolonged intubation, and increased transfusion relative to patients without genetic variants. Preoperative determination of APOE/TNFB genotypes in patients undergoing coronary artery bypass grafting may lead to additional perioperative measures to ameliorate systemic inflammatory response.

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.

Pharmacogenetic investigation of the TNF/TNF-receptor system in patients with chronic active Crohn's disease treated with infliximab

Infliximab (anti-TNF-alpha monoclonal antibody) induces remission in 30-40% of Crohn's disease patients. Treatment response is a stable trait. Two cohorts from independent, prospective clinical trials of infliximab in Crohn's disease were studied. Hypotheses were generated in an exploratory cohort (n = 90) and then tested in a confirmatory cohort (n = 444), using a statistical design, which is stable against type 1 and type 2 errors. In the exploratory cohort, the mutant 196Arg allele of TNFR-II (exon 6 polymorphism) and a novel silent polymorphism in exon 2 of TNFR-II were associated with lack of response to infliximab (83.3% in homozygote mutant 196 Arg patients vs 36.9% in heterozygotes and wild-type homozygotes (P = 0.036) and 85.7% in homozygote mutant exon 2 patients vs 36.1% (P = 0.01), respectively). None of the homozygote mutant individuals (0/6) achieved clinical remission, whereas the remission rate was 35.7% (30/84) in wild-type homozygotes and heterozygotes. In the large second cohort, the observed genotype-phenotype associations were not replicated. Other polymorphisms (TNF-alpha promoter -238, -308, -376, -857, -1031, TNF-R-I -609, +36 (exon 1), TNF-R-II 1663, 1690 (3'-UTR)) were not associated with treatment response in both cohorts (P > 0.5). None of the polymorphisms was associated with refractory Crohn's disease itself when compared to healthy controls. In a two-cohort study, a series of polymorphisms in the TNF, the TNF-R-I and in the TNF-R-II genes could be thoroughly excluded as pharmacogenetic markers for a treatment response to infliximab and as etiologic factors for Crohn's disease, respectively. The discrepancy between the two cohorts observed for the TNF-R-II exon 6 and exon 2 polymorphism may point to a weak effect on treatment response but also serves to illustrate the need for a sequential exploratory/confirmatory design in pharmacogenetic studies.

Single-nucleotide polymorphisms in tumor necrosis factor receptor genes: definition of novel haplotypes and racial/ethnic differences

OBJECTIVE

To characterize allele frequencies of known single-nucleotide polymorphisms (SNPs) in tumor necrosis factor receptor (TNFR) genes in African Americans with rheumatoid arthritis (RA), healthy African Americans, and healthy Caucasians.

METHODS

One TNFRSF1B SNP (196 G/T) that influences susceptibility to familial RA in Caucasians and 3 SNPs in the 5' flanking region of the TNFRSF1A gene (-609G/T, -580A/G, and -383A/C) were genotyped in 108 African Americans with RA, 62 healthy African Americans, and 59 healthy Caucasians.

RESULTS

There were no differences in TNFRSF1A allele frequencies between African Americans with RA and healthy African Americans. Allele frequencies were strikingly different, however, between healthy African Americans and healthy Caucasians: 0.13 versus 0.42 for -609T, 0.49 versus 0 for -580G, and 0.14 versus 0 for -383C. We identified 4 novel haplotypes defined by the 3 TNFRSF1A SNPs, the distribution of which was markedly different in healthy Caucasians and healthy African Americans (P = 0.000001 by chi-square test-. The frequencies of the TNFRSF1B 196 genotypes were similar in African Americans with RA and healthy African Americans but differed between healthy African Americans and healthy Caucasians (P = 0.05).

CONCLUSION

Although we observed no associations between known TNFR SNPs or haplotypes and RA, significant racial differences were observed at both loci. Comparison of these data with other published frequencies of TNFRSF1A and TNFRSF1B genotypes according to race suggests that the distribution in African American, Caucasian, and Asian populations differs significantly. These striking racial/ethnic differences in TNFR SNP frequencies may influence the likelihood of familial RA, severe disease, or response to TNF inhibitors and may have important evolutionary implications.

Identifying disease modifying genes in multiple sclerosis

Evidence is mounting that genetic variation influences not only susceptibility to multiple sclerosis (MS), but also its course and severity. Identification of disease modifying genes, however, poses unique challenges, especially on how to classify the course and outcome of the disease in ways that may be relevant to analysis of biological factors that might be influenced by genes. The power of the statistical approaches to detect small effects of individual genes in complex disorders such as MS is problematic, and approaches to estimate power must be appropriate for the data. Nonetheless, using contemporary schemes of classification, genetic variants that influence disease course have been found; in fact, a small number have been confirmed to influence disease course in two or more independent studies. This review addresses strategies relevant to identification of disease modifying genes in MS, and summarizes and critically evaluates the current state of knowledge in this area.

HLA-DR 15 is associated with female sex and younger age at diagnosis in multiple sclerosis

BACKGROUND

The association between multiple sclerosis and class II alleles of the major histocompatibility complex, in particular the DRB1*1501-DQB1*0602 haplotype, is well established but their role in determining specific features of this clinically heterogeneous disease is unknown as few studies involving large sample sizes have been performed.

METHODS

729 patients with multiple sclerosis were typed for the HLA DR15 phenotype. All patients underwent clinical assessment and a detailed evaluation of their clinical records was undertaken.

RESULTS

The presence of DR15 was associated with younger age at diagnosis and female sex but there was no association with disease course (relapsing-remitting or secondary progressive v primary progressive type), disease outcome, specific clinical features (opticospinal v disseminated form), diagnostic certainty (clinically and laboratory supported definite v clinically probable multiple sclerosis), and paraclinical investigations including the presence of oligoclonal bands in the CSF or characteristic abnormalities on MRI imaging of the central nervous system.

CONCLUSION

Even though DR15 carriers are more likely to be female and prone to an earlier disease onset, the results indicate that there is no association with other specific clinical outcomes or laboratory indices examined here. This suggests that DR15 exerts a susceptibility rather than disease modifying effect in multiple sclerosis.

Polymorphisms in the TNF-alpha and TNF-receptor genes in patients with coronary artery disease

BACKGROUND

Coronary artery disease (CAD) is both multifactorial and polygenic in nature. Atheroma formation, the pathological hallmark of CAD, is an inflammatory process, with pro-inflammatory cytokines, such as tumour necrosis factor-alpha (TNF-alpha), having a major role in its pathogenesis. We have therefore investigated whether polymorphisms in the TNF-alpha (- 238 and - 308), TNF receptor 1 (position - 609 and + 10, intron 6) and TNF receptor 2 (position + 422, codon 198) genes show an association with CAD.

MATERIALS AND METHODS

Patients with angiographically proven single vessel (n = 58) and multivessel (n = 122) CAD were compared to patients with angiographically proven normal coronary arteries (n = 79) and volunteers without clinical evidence of CAD (n = 250). Genotyping was performed by PCR-RFLP analysis. For the TNF-alpha polymorphisms, a meta-analysis of all published studies was also undertaken.

RESULTS

No significant differences in allele or genotype frequencies were found between the normal coronary artery group or healthy volunteers and patients with CAD for any of the polymorphisms. There was also no difference in allele frequency between patients with single- and multivessel disease. For the - 308 and - 238 TNRalpha gene polymorphisms, a meta-analysis of our data and previously published studies failed to demonstrate any significant association with CAD.

CONCLUSIONS

Polymorphisms in the TNF-alpha promoter region and TNF-receptor genes are not associated with the development of CAD.

[Multiple sclerosis: pathogenesis and manifestations in children]

Multiple sclerosis (MS) is rare in children and occurs exceptionally before ten years. Sex ratio (girl/boy) is around 2.5 to 3, higher than in adults. Brain stem dysfunction and meningeal symptoms are more commonly first manifestations of the disease than in adults. Optic neuritis is also a frequent early manifestation. The etiology of the disease remains unclear and none of the advanced hypotheses (infectious, genetic, environmental) can by themselves explain its occurrence. There is a genetic susceptibility which is probably linked to many genes leading to a low related risk (less than two). A viral trigger mechanism in a person with a genetic predisposition is possible. New therapies result from a better understanding of the closed immune mechanisms of the disease.