Toll-like Receptor 4 Gene Asp299Gly Research Articles

Toll-like receptor 4 gene Asp299Gly polymorphism in myocardial infarction: A meta-analysis of 15,148 subjects

It remains controversial regarding the association between toll-like receptor 4 (TLR4) gene Asp299Gly (+896 A/G) polymorphism and myocardial infarction (MI) risk. Thus, a large-scale meta-analysis evaluating the potential association between this gene variant and MI risk is required. PubMed, Embase, Web of Science, CBMdisc, CNKI, and Google Scholar were searched until February 6, 2013. All the statistical tests were performed using Stata 11.0. Nine articles involving 10 studies were included in the final meta-analysis, covering a total of 8299 MI cases and 6849 controls. Overall, no significant association was found between the TLR4 gene Asp299Gly polymorphism and MI risk (G allele vs. A allele: OR=0.95, 95% CI=0.74–1.22, p=0.71; G/G vs. A/A: OR=1.03, 95% CI=0.54–1.98, p=0.93; G/G vs. A/G+A/A: OR=1.05, 95% CI=0.55–2.03, p=0.87; G/G+A/G vs. A/A: OR=0.92, 95% CI=0.75–1.13, p=0.42). In the subgroup analysis based on source of controls, there was also lack of evidence for significant association between the TLR4 gene Asp299Gly polymorphism and MI risk. In summary, the present meta-analysis indicated that the TLR4 gene Asp299Gly polymorphism was not associated with MI risk.

Toll-like receptor 4 gene Asp299Gly polymorphism in ischemic cerebrovascular disease: a meta-analysis

Epidemiological studies have evaluated the association between Toll-like receptor 4 (TLR4) gene Asp299Gly (rs4986790) polymorphism and the risk of ischemic cerebrovascular disease, but the results are inconsistent. In an effort to clarify earlier inconclusive results, a meta-analysis was performed. We searched the PubMed, Web of Science, Embase, Cochrane database, Clinicaltrials.gov, Current Controlled Trials, CNKI, CBMdisc, Chinese Clinical Trial Registry and Google Scholar until up to 20 July 2013. Additionally, hand searching of the references of identified articles was performed. Original observational studies investigating the association between TLR4 gene Asp299Gly polymorphism and ischemic cerebrovascular disease risk were included. All statistical analyses were performed using Stata 11.0. The search strategy identified 1038 potentially relevant articles, seven of which were included in the final meta-analysis, covering a total of 1767 cases and 2785 controls. Overall, no significant association was found between TLR4 gene Asp299Gly polymorphism and ischemic cerebrovascular disease risk (for G allele versus A allele: OR = 0.95, 95% CI = 0.75–1.21, p = 0.69; for G/G+A/G versus A/A: OR = 0.96, 95% CI = 0.75–1.22, p = 0.73). In addition, the similar results were obtained in the sensitivity analysis based on studies with the high quality. In summary, the present meta-analysis indicates that TLR4 gene Asp299Gly polymorphism is not associated with increased ischemic cerebrovascular disease risk.

Interleukin-17 serum levels and TLR4 polymorphisms in ulcerative colitis.

Inflammatory bowel disease, an autoimmune disease, has two clinical manifestations including Crohn's disease and ulcerative colitis (UC). IL-17 has been the target of intensive research in autoimmune diseases. The influence of Toll like receptor 4 (TLR-4) gene polymorphisms on IL-17 production has also been revealed in UC patients and tissue inflammation in mice. To investigate the association between the TLR-4 gene polymorphisms, Asp299Gly and Thr399Ile and IL-17 serum levels with ulcerative colitis. Additionally, we aimed to study modulation effects of forenamed gene polymorphisms on IL-17 serum levels in UC patients and controls. A total of 256 healthy controls and 85 UC patients enrolled in our study. DNA was extracted and PCR-RFLP technique was employed to determine Asp299Gly and Thr399Ile polymorphisms in TLR-4 gene and IL-17 serum levels were measured by ELISA method. There was no significant difference between the frequency of Asp299Gly A>G and Thr399Ile C>T in UC patients and controls. While IL-17 serum levels in UC patients were significantly higher than controls (p=0.003), no significant difference in IL-17 levels between different genotypes existed. Additionally, a significant inverse relationship was observed between hemoglobin level and IL-17 serum levels in UC patients (p=0.039). Increased IL-17 serum levels in our UC patients might be explained through the synergistic activity of IL-17/IL-23 axis and pro-inflammatory cytokines, causing severe clinical outcome in patients with IBD. The prolonged excretion of blood in stool driven by inflammatory process which causes iron metabolism disorder and anemia may elucidate the inverse correlation between hemoglobin and IL-17 serum levels in UC patients. Lack of association between the TLR-4 gene polymorphisms and UC in our study was consistent with the results from other Caucasian populations.

Analysis of TLR4 and TLR2 polymorphisms in inflammatory bowel disease in a Guangxi Zhuang population

To study the polymorphisms of toll-like receptor 4 (TLR4) gene Asp299Gly, Thr399Ile and TLR2 gene Arg753Gln, Arg677Trp and susceptibility to inflammatory bowel disease (IBD) in the Zhuang population from Guangxi, China. A case-control study was performed from February 2007 to October 2011 which included 146 Zhuang patients with IBD in the experimental group and 164 healthy Zhuang subjects who acted as the control group. All patients and healthy subjects were from the Guangxi Zhuang Autonomous Region of China. Genomic DNA was extracted from intestinal tissue by the phenol chloroform method. TLR4 gene Asp299Gly, Thr399Ile and TLR2 gene Arg753Gln, Arg677Trp were amplified by polymerase chain reaction (PCR), and then detected by PCR-restriction fragment length polymorphism (RFLP). The TLR4 gene Asp299Gly was digested using Nco I restriction enzyme, and a single band of 249 bp was observed which showed that it was a wild type (AA). The TLR4 gene Thr399Ile was digested using Hinf Irestriction enzyme and only the wild type (CC) was detected. In addition, the TLR2 gene Arg677Trp was digested using Aci I restriction enzyme and only the wild type (CC) was detected. The TLR2 gene Arg753Gln was digested using Pst I restriction enzyme. Only the wild type (GG) as a single band of 254 bp was observed during RFLP. Overall, no heterozygous or homozygous single nucleotide polymorphism mutations were found in patients with Crohn's disease and ulcerative colitis both in the TLR4 gene Asp299Gly, Thr399Ile and the TLR2 gene Arg677Trp, Arg753Gln in the Zhuang population from the Guangxi Zhuang Autonomous Region of China. The TLR4 gene Asp299Gly, Thr399Ile and TLR2 gene Arg753Gln, Arg677Trp polymorphisms may not be associated with IBD in the Zhuang population from the Guangxi Zhuang Autonomous Region of China.

Associations between variations in the TLR4 gene and incident coronary heart disease (CHD) in middle-aged men and women: Results from the MONICA/KORA Augsburg case-cohort study, 1984–2002

Background: Toll-like receptor 4 (TLR4), the signalling receptor for lipopolysaccharides, is an important member of the innate immunity system. Since several studies have suggested that atherosclerosis might be associated with changes in the innate immune response, and a SNP in the TLR4 gene (Asp299Gly; Kiechl et al, N Engl J Med 2002;347:185–92) was shown to be associated with a decreased risk of atherosclerosis, we sought to investigate the impact of gene variants in the TLR4 gene on incident CHD. Methods: A case-cohort study was conducted in initially healthy, middle-aged men and women based on data from the MONICA/KORA Augsburg studies collected between 1984 and 2002, with a mean FU of 10.2±4.8 years. The present analyses are based on 318 case subjects with incident CHD and 1,727 non-case subjects. Seven SNPs (rs2770150; rs6478317; rs1927911; rs2149356; rs4986791; rs7873784; rs1927906) were systematically selected in the TLR4 gene, and haplotypes were constructed. Results: TLR4 genotype distribution did not significantly differ among subjects with incident CHD and non-case subjects. No significant interactions between any of the SNPs and major cardiovascular risk factors on CHD risk were found. There was no consistent association between the 7 different SNPs within the TLR4 gene and incident CHD in crude and in multivariable adjusted analyses, neither for men and women separately, nor in a model that included all study participants. Conclusions: In contrast to an earlier and smaller prospective study, we could not confirm an association between various SNPs within the TLR4 gene and incident CHD. The presence of various alleles of the TLR4 gene, including Asp299Gly, does not seem to exert a major influence on the progression of atherosclerosis in the general population.

Lack of association of TLR4 gene Asp299Gly and Thr399Ile polymorphisms with rheumatoid arthritis in Chinese Han population of Yunnan Province

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic inflammation of synovium and subsequent joint destruction. Recently, genetic polymorphisms within the toll-like receptor 4 (TLR4) genes have been reported to be associated with RA. To analyze the association between the genetic polymorphisms within TLR4 gene and the susceptibility to RA in Chinese people, two functional variants, Asp299Gly and Thr399Ile, in the TLR4 gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and direct sequencing techniques from 213 RA patients and 247 ethnically matched controls. None polymorphisms of Asp299Gly and Thr399Ile were detected in all RA cases and controls, which indicates that there is no relevance between these two SNPs and RA in the Chinese Han population. Further studies with extended single nucleotide polymorphisms (SNP) should be performed.

NOD2/CARD15 and TLR4 single nucleotide polymorphisms (SNPs) in a cohort population with Inflammatory Bowel Disease from South of Italy: Survey of genotype–phenotype correlations

Background. Diagnosis of Crohn’s disease (CD) and lcerative colitis (UC) are based on well-established clinial and pathological criteria. Recently significant progress as occurred to understand genetic variations associated to athogenic mechanisms and development of predictive risk odels to predicting diseases outcome and responses of conentional therapies. There is evidence that NOD2/CARD15 nd Toll-like receptor 4 (TLR4) mutations are involved in the athogenesis of CD. No analysis of NOD2/CARD15 gene ariants has so far been reported in selected population (paeiatric and adult) coming from two selected regions of the outh of Italy (Sicily and Calabria). Aim. In this study we investigated the single nucleotide olymorphisms (SNPs) of the NOD2/CARD15 gene R702W, G908R and L1007fsinsC), and of the TLR4 gene Asp299Gly and Thr399Ile) in selected population with nflammatory bowel diseases (IBD) coming from South of taly. Methods. DNA was obtained from 133 patients (35% f paediatric patients with medium age 4–15 years old) ith CD, 45 (40% of paediatric patient with medium age -12 years) with UC and 103 healthy controls. Genotypng was performed by PCR-RFLP analysis and by DNA utomatic sequencing. Allele and genotype frequencies of OD2/CARD15 (R702W, G908R and L1007fsinsC) and LR4 (Asp299Gly and Thr399Ile) genetic variants were xamined in CD and UC patients and genotype-phenotype orrelation was performed. Results. The NOD2/CARD15 R702W mutation was sigificantly more frequent in CD (9.8%) than in controls 2.4%, p= 0.001) and in UC (2.3%, p= 0.03). No signifiant difference was found between UC patients and control roup (p= ns). In CD and UC patients, no significant assoiation with G908R variant was found and L1007fsinsC NP showed a significant association with CD (9.8%) comared with controls (2.9%, p= 0.002) or UC patients (2.3%, = 0.01). Moreover in CD patients G908R mutation was ssociated significantly with stenosing phenotype (p= 0.03) nd resective surgery risk (p= 0.003). In the L1007fsinsC hetrozygotes there was a higher frequency of ileal localization 80.7%, p= 0.001) and resective surgery (53.9%, p= 0.01) in espect to CD wild-type patients (ileum 36.8% and resective 3 p s d ease 40 (2008) A41–A118 A45

Rarity of TLR4 Asp299Gly and Thr399Ile Polymorphisms in the Korean Population

PurposeActivation of the innate immune system and chronic low-grade inflammation are thought to be involved in the pathogenesis of atherosclerosis and also thought to be associated with type 2 diabetes and its complications. As a receptor for bacterial lipopolysaccharide and heat-shock proteins, Toll-like receptor 4 (TLR4) is one of the central regulators of the immune response. Recent studies have reported an association between TLR4 polymorphisms and diabetes and its complications in Caucasian populations.Materials and MethodsIn this study, we analyzed the association between TLR4 gene polymorphisms in patients with features of type 2 diabetes and healthy controls in Korea. Two polymorphisms of the TLR4 gene (Asp299Gly and Thr399Ile) were examined in 225 diabetic patients and 153 healthy controls using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and single-strand conformation polymorphism (SSCP).ResultsNo Asp299Gly or Thr399Ile mutations were detected in any of the 378 subjects. Seven subjects from each group who had slightly different SSCP patterns were selected for sequencing, but we found no TLR4 polymorphisms on Exon3. The Asp299Gly and Thr399Ile TLR4 gene polymorphisms were absent in both groups, which was similar to the results for Japanese and Chinese Han subjects.ConclusionOur data and other Asian data suggest that a racial difference can be found in the frequency of the TLR4 polymorphism.

Toll-like receptor 4 gene (Asp299Gly) polymorphism associates with carotid artery elasticity: The cardiovascular risk in young Finns study

Objective Early subclinical markers of atherosclerosis, such as carotid artery intima media thickness (IMT) and elasticity predict future coronary events. The G allele of the Toll-like receptor 4 (TLR-4) gene Asp299Gly polymorphism has been previously associated with decreased development of atherosclerosis and with lower risk of myocardial infractions. We wanted to examine the association of this polymorphism with carotid IMT and compliance in a population of young Finnish Caucasian adults. Methods Carotid artery IMT and elasticity indices of 2201 study subjects who participated in a randomized multicenter study (cardiovascular risk in young Finns study) were measured with ultrasound. The genotyping was performed using the TaqMan 5′-nuclease assay. Results According to multivariate linear regression analysis adjusted with potential confounders, the G allele carriers had significantly higher carotid arterial compliance, measured in increase of luminal diameter percentage in response to blood pressure rise of 10 mmHg, than did the AA homozygotes ( β = 0.099 with 95% CI 0.029–0.169 and p = 0.006). The difference between AA homozygotes and GG homozygotes was even more pronounced ( β = 0.382 with 95% CI 0.119–0.644 and p = 0.004). Variation in the TLR-4 genotype was not related with IMT. The results of the two independent study cohorts of Eastern and Western Finland were in accordance with the results of the whole combined study population. Conclusion The G allele of the TLR-4 gene Asp299Gly polymorphism is associated with increased carotid artery compliance in young adults. This beneficial effect of the G allele may reduce the risk of future cardiovascular events.

TLR4 polymorphism in Iranian patients with brucellosis

Brucellosis is a zoonosis of both public health and economic significance in most developing countries. Polymorphisms in Toll-like receptor-4 (TLR4) have been reported to be associated with a blunted immune response to microbial pathogens. Information regarding any association between genetic variation of TLR4 and susceptibility to brucellosis is not available in the literatures. The main purpose of this research is to evaluate the role of polymorphic alleles of TLR4 gene in susceptibility to brucellosis. In this case-control study, 198 patients with brucellosis and 111 healthy volunteers matched for sex, age and geographic area were evaluated by genotyping for polymorphism in TLR4 gene (Asp299Gly) using amplification refractory mutation system (ARMS)-PCR method. Allele 896G was more prevalent in patients with brucellosis compared to healthy controls (33.6% vs. 20.7%, P=0.000003). Also the frequency of G allele of TLR4 gene was significantly higher in male patients with brucellosis compared to the same sex in control group (36% vs. 21.7%, P=0.00005). Multiple logistic regression analysis demonstrated that male patients heterozygous at allele G gene had a significantly higher risk for brucellosis with an odds ratio of OR 2.89, 95% CI: 1.79-4.69, P<0.0001). This study is the first to show an association between genetic polymorphism in TLR4 gene and susceptibility to brucellosis.

Relationship between In Vitro Lipopolysaccharide-Induced Cytokine Response in Whole Blood, Angiographic In-Stent Restenosis, and Toll-Like Receptor 4 Gene Polymorphisms

In coronary in-stent restenosis (ISR), a substantial contribution of inflammation is assumed. We evaluated the association between polymorphisms in the Toll-like receptor 4 (TLR4) gene and cytokine response after lipopolysaccharide (LPS) challenge and the development of ISR. Patients were included after successful elective stent placement in a native coronary artery and were scheduled for follow-up angiography after 6 months. Quantitative coronary analysis was performed off-line. Patient whole blood was challenged with LPS for 24 h. Baseline and stimulated concentrations of interleukin (IL)-1beta, IL-6, tumor necrosis factor-alpha, and IL-10 were assessed by ELISA. Two cosegregating single-nucleotide polymorphisms in the TLR4 gene (Asp299Gly and Thr399Ile) were analyzed by allele-specific PCR amplification of genomic DNA. A total of 236 consecutive patients were included, and 40 (17%) developed ISR. Median baseline and stimulated cytokine concentrations did not differ between patients with and without ISR. In multivariate analysis, male sex, unstable angina, hypertension, and chronic total occlusion were predictors of ISR. TLR4 genotypes were not associated with baseline or stimulated cytokine concentrations or with angiographic variables at follow-up. In vitro cytokine response to LPS challenge is not increased in patients with ISR. Functionality of the TLR4 Asp299Gly polymorphism could not be demonstrated in this setting, and this polymorphism was not associated with angiographic outcome, calling into question its role in the progression of neointimal tissue growth.

Association between polymorphisms in the Toll-like receptor 4, CD14, andCARD15/NOD2and inflammatory bowel disease in the Greek population

Crohn's disease (CD) and ulcerative colitis (UC) are multifactorial diseases with a significant genetic background. Apart from CARD15/NOD2 gene, evidence is accumulating that molecules related to the innate immune response such as CD14 or Toll-like receptor 4 (TLR4), are involved in their pathogenesis. In further exploring the genetic background of these diseases, we investigated the variations in the CARD15/NOD2 gene (Arg702Trp, Gly908Arg and Leu1007fsinsC), and polymorphisms in the TLR4 gene (Asp299Gly and Thr399Ile) as well as in the promoter of the CD14 gene (T/C at position -159) in Greek patients with CD and UC. DNA was obtained from 120 patients with CD, 85 with UC and 100 healthy individuals. Genotyping was performed by allele specific PCR or by PCR-RFLP analysis. The 299Gly allele frequency of the TLR4 gene and the T allele and TT genotype frequencies of the CD14 promoter were significantly higher in CD patients only compared to healthy individuals (P = 0.026<0.05; P = 0.0048<0.01 and P = 0.047<0.05 respectively). Concerning the NOD2/CARD15 mutations the overall presence in CD patients was significantly higher than that in UC patients or in controls. Additionally, 51.67% of the CD patients were carriers of a TLR4 and/or CD14 polymorphic allele and at least one variant of the NOD2/CARD15, compared to 27% of the UC patients. It should be pointed out that both frequencies significantly increased as compared with the 10% frequency of multiple carriers found in healthy controls. A possible interaction of the NOD2/CARD15 with TLR4 and especially CD14, increased the risk of developing inflammatory bowel disease (IBD). Our results indicate that co-existence of a mutation in either the TLR4 or CD14 gene, and in NOD2/CARD15 is associated with an increased susceptibility to developing CD compared to UC, and to developing either CD or UC compared to healthy individuals.

Variation in the toll-like receptor 4 gene and susceptibility to myocardial infarction

Variation in the gene encoding toll-like receptor 4 (TLR4), a transmembrane receptor that mediates inflammatory responses to bacterial endotoxin, has been associated with susceptibility to atherosclerosis and its complications, such as myocardial infarction (MI), the pathogenesis of which involves inflammation. A recent study has also indicated that TLR4 gene variation influences the effect of statin treatment on reducing atherosclerosis complications. We studied the TLR4 gene Asp299Gly polymorphism in relation to susceptibility to myocardial infarction in a cohort of patients with angiographically documented coronary artery disease, and performed a meta-analysis using data sets from three independent studies. The meta-analysis showed that overall, odds ratio (OR) for MI was 0.73 [95% confidence interval (CI) 0.55-0.96, P=0.024] in 299Gly carriers compared to non-carriers, and there was no evidence of heterogeneity among the sample sets (P=0.679). In our patient cohort, a significant association of 299Gly bearing genotypes with lower susceptibility to myocardial infarction was observed only in patients receiving statin treatment, with 299Gly carriers having an OR of 0.49 (95% CI 0.27-0.78, P=0.015) for MI compared to non-carriers. These results are consistent with the notion that variation in the TLR4 gene contributes to inter-individual variability in susceptibility to coronary ischaemic events, and that TLR4 genotype and statin treatment may have a synergistic effect.

Lack of association between polymorphisms of the toll-like receptor 4 gene and cerebral ischemia.

Toll-like receptor-4 (TLR4), an important mediator of the innate immune response, is expressed in atherosclerotic lesions. The common single nucleotide exchange (Asp299Gly) of the TLR4 gene has been previously reported to impair TLR4 function and to be associated with a decreased risk of carotid atherosclerosis. Therefore, we aimed to detect the potential impact of TLR4 genotypes on the risk of cerebral ischemia. We studied the prevalence of two common polymorphisms of the TLR4 gene (Asp299Gly and Thr399Ile) in 3 independent study populations: (1.) in a cross-sectional study including 769 patients either with type 1 or type 2 diabetes mellitus, of whom 56 (7.2%) had a history of cerebral ischemia (study 1), (2.) a case-control study (study 2) including 128 consecutive patients with cerebral ischemia, mean age 60 +/- 10.9 years and 139 control subjects, and (3.) a case-control study (study 3) including 171 young adults aged < 50 years with cerebral ischemia and 204 control individuals. In all subjects, Asp299Gly and Thr399Ile were detected by restriction length analysis. The prevalence of the TLR4 genotypes was essentially the same between patients with cerebral ischemia and control subjects in all 3 study populations. Furthermore, there was also no association with the subgroup of atherosclerotic stroke in both case-control studies populations. Although TLR4 polymorphisms are associated with a decreased risk of carotid atherosclerotic lesions, our findings indicate that they do not influence the prevalence of cerebral ischemia. This implies that the Asp299Gly TLR4-allele might have a protective role in carotid atherosclerosis, but not in cerebral ischemia.

Monocytes heterozygous for the Asp299Gly and Thr399Ile mutations in the Toll-like receptor 4 gene show no deficit in lipopolysaccharide signalling.

Toll-like receptor 4 (TLR4)-mediated recognition of lipopolysaccharide (LPS) is required for efficient recognition of Gram-negative bacterial infections. Two commonly occurring mutations in the human TLR4 gene (Asp299Gly and Thr399Ile) have recently been shown to be associated with blunted physiological responses to inhaled LPS, and with increased risk of Gram-negative bacteraemia in sepsis patients and reduced risk of atherosclerosis in an Italian population. Here we show that monocytes from individuals heterozygous for both mutations in the TLR4 gene exhibit no deficit in recognition of LPS of Escherichia coli, Neisseria meningitidis, Bacteroides fragilis, Yersinia pestis, Chlamydia trachomatis, Porphyromonas gingivalis, or Pseudomonas aeruginosa. We propose that the relatively high frequency of these mutations in the Caucasian population may reflect modified responses of carriers to alternative TLR4 agonists.