Thr399Ile Polymorphisms Research Articles

Toll-like receptor 4 and inducible nitric oxide synthase gene polymorphisms are associated with Type 2 diabetes

Background The toll-like receptor 4 (TLR4) and inducible nitric oxide synthase are proteins from the innate immune system that, when activated, can induce insulin resistance. Polymorphisms in these genes, TLR4 and NOS2, respectively, could affect the immune response, as well as the prevalence of Type 2 diabetes (T2DM). Objective The aim of the present study was to investigate the contribution of four polymorphisms (two from TLR4 and two from NOS2) to susceptibility to T2DM in a southeast Brazilian population. Design A total of 211 patients with T2DM and 200 unrelated controls were genotyped for the Asp299Gly and Thr399Ile polymorphisms of the TLR4 gene and for the insertion (I)/deletion (D) AAAT and (CCTTT)n polymorphisms of the NOS2 promoter gene. Results With regard to the NOS2 promoter region, the data showed that the I allele of the I/D AAAT polymorphism was more prevalent in the T2DM group and that the L/L genotype of the (CCTTT)n polymorphism was also more frequent in the same group. In contrast, the 299Gly allele and the 399Ile allele from the Asp299Gly and Thr399Ile TLR4 gene polymorphisms, respectively, were associated with protection of T2DM. It is believed that the persistence of these genetic variations in human populations may be indicative of a selective advantage in the face of different environmental pressures. Conclusions Genetic variations in the NOS2 gene promoter and TLR4 coding sequence may lead to deleterious and protective effects, respectively, arising from altered function of the innate immune system in patients with T2DM.

TLR4 as a risk factor for periodontal disease: a reappraisal

To determine whether genetic variants of the TLR4 gene are associated with either chronic or aggressive periodontitis. A systematic electronic search of literature was conducted to identify all published studies without any language restriction on the association between TLR4 and periodontal diseases, including chronic periodontitis and aggressive periodontitis. All case-control studies evaluating the TLR4 Asp299Gly and Thr399Ile polymorphisms in chronic or aggressive periodontitis were identified. A meta-analysis of the studies that fulfilled the inclusion criteria was performed. Seven studies comprising 744 chronic periodontitis cases and 855 controls and four studies consisting of a total of 295 aggressive periodontitis cases and 456 controls were included in the meta-analysis. In the pooled analysis, the TLR4 299Gly allele (TLR4+896 A>G) appeared to be a genetic risk factor for susceptibility to chronic periodontitis with a random effects and fixed effects odds ratio (OR) of 1.43 [95% confidence interval (CI):1.04-1.97; p=0.03]. On the other hand, the TLR4 399Ile polymorphism (TLR4+1196 C>T) showed a protective effect against aggressive periodontitis with a random effects OR of 0.29 (95% CI: 0.13-0.61; p=0.001). Our results suggest that the alleles 299Gly and 399Ile in TLR4 can be a potential genetic marker for periodontal disease.

Microsatellite polymorphism in intron 2 of human Toll-like receptor 2 gene is associated with susceptibility to acute pancreatitis in Japan

This study evaluated the association of the polymorphisms in the Toll-like receptor (TLR)2 and TLR4 genes with acute pancreatitis (AP) in Japan. The numbers of guanine-thymine [(GT) n ] repeats in intron 2 of the TLR2 gene were counted in 202 unrelated patients with AP (80 with severe and 122 with mild disease) and in 286 healthy controls, using polymerase chain reaction and Genescan analysis. The alleles were divided into three subclasses: (GT) 16 or less as the S allele; between (GT) 17 and (GT) 22 as the M allele; and (GT) 23 or more as the L allele. Asp299Gly and Thr399Ile polymorphisms in the TLR4 gene were examined by polymerase chain reaction–restriction fragment length polymorphism analysis. Patients with AP had more S alleles ( p < 0.001; odds ratio = 2.37; 95% confidence interval = 1.78–3.17) and fewer M alleles ( p < 0.001; odds ratio = 0.40; 95% confidence interval = 0.31–0.52) than did healthy controls. Genotypes SS and SL were more common, whereas MM and ML were less common in patients with AP. In subgroup analyses, the genotypes including S alleles were more common in patients with severe AP than in controls. No Asp299Gly and Thr399Ile polymorphisms were detected. In conclusion, microsatellite polymorphism in intron 2 of the TLR2 gene was associated with susceptibility to AP and its severity in Japan.

Toll‐Like Receptor 4 +3725 G/C Polymorphism, Helicobacter pylori Seropositivity, and the Risk of Gastric Atrophy and Gastric Cancer in Japanese

Toll-like receptor 4 (TLR4) Asp299Gly and Thr399Ile polymorphisms were reported to be a risk factor of gastric carcinoma or its precursors in Caucasian and Indian population, but these polymorphisms are absent in Japanese. We investigated the associations of TLR4+3725 G/C polymorphism, another functional polymorphism of TLR4, with risk of gastric cancer and gastric atrophy in Japanese. Study subjects were 583 histologically diagnosed gastric cancer patients and age- and sex-matched 1592 control outpatients, who visited Aichi Cancer Center Hospital from 2001 to 2005. Serum anti-H. pylori IgG antibody and pepsinogens were measured to evaluate H. pylori infection and gastric atrophy, respectively. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by a logistic model. Among the seropositive subjects, the age- and sex-adjusted OR of gastric atrophy was 1.17 (95%CI: 0.91-1.50) for G/C, 1.20 (95%CI: 0.76-1.89) for C/C, and 1.18 (95%CI: 0.93-1.49) for G/C+C/C relative to G/G genotype. The age- and sex-adjusted OR of severe gastric atrophy among H. pylori seropositive subjects was 1.43 (95%CI: 0.99-2.06) for G/C, 1.47 (95%CI: 0.76-2.88) for C/C, and 1.43 (95%CI: 1.01-2.04) for G/C+C/C. The OR of gastric cancer compared with gastric atrophy controls was not statistically significant. Our study found that TLR4+3725 G/C polymorphism was a risk factor of severe gastric atrophy in H. pylori seropositive Japanese. Our results underscored the significance of the variations in host innate immunity due to TLR4 polymorphism as genetic predispositions to gastric precancerous lesions in Eastern Asian populations with the same backgrounds.

Toll-like receptor 4 gene polymorphism and early onset of diabetic retinopathy in patients with type 2 diabetes

Toll-like receptor 4 (TLR4) is an important mediator of innate immunity. Type 2 diabetes (DM2) might be associated with changed innate immune response. We investigated whether the polymorphisms in the TLR4 gene are associated with diabetic retinopathy (DR). The study group of 864 patients with DM2 and 420 healthy individuals were genotyped. In the patient group 352 subjects were diagnosed with DR. Out of the remaining 512, 140 had DM2 for ≥ 10 years but no DR. In the DM2 group 7.4% of patients were heterozygous for the Asp299 Gly polymorphism compared with 6.5% controls. For Thr399 Ile polymorphism there were 7.2% heterozygotes vs 6.2% controls. In most cases, the linkage disequilibrium between the minor alleles Gly299 and Ile399 was confirmed. Increased frequency of both heterozygous genotypes was observed in patients with retinopathy (11.2% for the Asp299 Gly). The frequency of the G allele was significantly higher in patients with early onset retinopathy ( n = 80) vs patients without DR (odds ratio = 5.0, and 95% confidence interval = 2.33–10.71). In contrast, in the entire retinopathy group, the odds ratio for the G allele was 1.88 (95% confidence interval = 0.93–3.79). In the multivariate logistic regression analysis, the G allele of Asp299Gly was an independent risk factor of early onset DR ( p < 0.001). In conclusion, our results suggest an association between the Asp299 Gly polymorphism of the TLR4 gene and early onset of DR in the DM2 patients. Thus the G allele may be a predictor of increased risk of retinopathy.

Toll-like receptor 4 Asp299Gly and Thr399Ile polymorphisms in gastric cancer of intestinal and diffuse histotypes.

In the present study we investigated the potential role of Toll-like receptor 4 (TLR-4) Asp299Gly and Thr399Ile polymorphisms as risk factors in the development of gastric cancer. TLR-4 Asp299Gly and Thr399Ile polymorphisms were investigated in 171 Italian patients with sporadic gastric cancer and in 151 controls. Unconditional regression (odds ratio and 95% confidence intervals) were used to investigate the association of the studied polymorphisms with gastric cancer. TLR-4 Thr399Ile polymorphism is linked with an increased susceptibility to gastric cancer (P = 0.023 and hazard ratio = 3.62). No significant association for TLR-4 Asp299Gly polymorphism was found. In the subgroup of patients with intestinal-type gastric cancer, a significant risk of gastric cancer was associated with TLR-4 Thr399Ile genotype (P = 0.006). Our results demonstrated that TLR-4 Thr399Ile polymorphism is linked with an increased susceptibility to gastric cancer. An increased risk for intestinal gastric cancer in carriers of the TLR4 Thr399Ile allele was observed. Future epidemiological studies should consider the possible interactions between proinflammatory genotypes (such as TLR and interleukin-1R polymorphisms) and other risk factors for cancer such as dietary habits and/or exposure to environmental carcinogens.

STUDY OF INFLAMMATORY CYTOKINES AND ENOS GENE POLYMORPHISM IN PREGNANCY INDUCED HYPERTENSION

Evidence showed that, pro inflammatory cytokines and mediators of innate immune responses may involve in the pathogenesis of preeclampsia (PE). Therefore, the present investigation aimed to examine the possible effects of placental TNF-α and TLR4 polymorphisms on PE susceptibility.The placental tissues were collected after delivery from 111 PE and 115 healthy pregnant women. The TNF-α-308G/A (rs1800629), TNF-α-238G/A (rs361525), TLR4 Asp299Gly (rs4986790) and TLR4 Thr399Ile (rs4986791) polymorphisms were genotyped using PCR-RFLP method. Moreover, in-silico analysis was performed to evaluate the potential functions of these polymorphisms.The TNF-α −308 GA genotype was associated with a decreased PE risk. The frequency of TNF-α −238G/A genotypes did not differ between two groups, however, the frequency of TNF-α −238A allele was significantly higher in controls. No relationship between TLR4 Thr399Ile and Asp299Gly polymorphisms and PE was found. In-silico analysis predicted that −308G to A substitution in the TNF-α promoter might lead to different allelic expressions. In addition, TLR4 Asp299Gly polymorphism would result in a major change in the mRNA and protein functions.Our study for the first time presented evidence on the association of the placental TNF-α −308GA genotype and TNF-α −238A allele with decreased risk of PE in an Iranian population.

Polymorphisms of toll-like receptor 2 and 4 genes in Chagas disease

The aim of this study was to test the possible implication of toll-like receptor 2 (TLR2) and TLR4 gene polymorphisms in determining the susceptibility to Chagas' disease. Genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism in 475 individuals from Colombia, 143 seropositive with chagasic cardiomyopathy, 132 seropositive asymptomatic and 200 seronegative. The TLR2 arginine to glutamine substitution at residue 753(Arg753Gln) polymorphism was absent in the groups analyzed. The TLR4 Asp299Gly and Thr399Ile polymorphisms are in linkage disequilibrium and we observed a very low frequency of these polymorphisms in our study population (2.6% and 1.8% respectively). The overall TLR2 and TLR4 alleles and genotype distribution in seronegative and seropositive were not significantly different. We compared the frequencies between asymptomatic patients and those with chagasic cardiomyopathy and we did not observe any significant differences in the distribution of alleles or genotypes. In summary, this study corroborates the low frequency of TLR2 and TLR4 polymorphisms observed in other populations and suggest that these do not play an important role in Chagas' disease. The validation of these findings in independent cohorts is needed to firmly establish a role for TLR2 and TLR4 variants in Chagas' disease.

Toll-Like Receptor 4 Gene Polymorphisms and Preeclampsia: Lack of Association in a Caucasian Population

Preeclampsia is a multifactorial disorder with genetic and environmental components. As Toll-like receptor 4 (TLR4) has an essential role in innate immune response, which is exaggeratedly activated in preeclampsia, our aim was to investigate whether two single nucleotide polymorphisms (SNPs) of the TLR4 gene--Asp299Gly (A896G) and Thr399Ile (C1196T)--are associated with preeclampsia in a Caucasian population from Hungary. In a case-control study, we analyzed blood samples from 180 preeclamptic patients and 172 normotensive, healthy pregnant women with the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method. The linkage disequilibrium (LD) profile of the TLR4 gene was investigated and tag SNPs were identified using data from the International HapMap Project. There were no significant differences in the genotype and allele frequencies of Asp299Gly and Thr399Ile polymorphisms between the two study groups. Additionally, no significant difference was found in the distribution of the estimated haplotypes created by the two polymorphisms between the preeclamptic and the control group. Furthermore, no significant differences were detected in the genotype, allele and haplotype frequencies of Asp299Gly and Thr399Ile TLR4 SNPs between patients with mild and severe preeclampsia, between patients with late and early onset of the disease, or between preeclamptic patients with and without fetal growth restriction. In conclusion, we did not find an association between TLR4 Asp299Gly and Thr399Ile gene polymorphisms and preeclampsia. As the Thr399Ile polymorphism is a highly informative tag SNP of the TLR4 gene, our results suggest that variations in this genomic region are not associated with preeclampsia. Nevertheless, further studies are required with determination of fetal TLR4 genotypes to explore the role of TLR4 gene polymorphisms in the risk of preeclampsia, especially in ethnically different populations.

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 2 and 4 Gene Polymorphisms in Generalized Aggressive Periodontitis

Toll-like receptors (TLRs) recognize exogenous ligands such as lipopolysaccharide and bacterial lipoprotein during the immune responses to pathogens. The aim of the present study was to investigate whether TLR2 and TLR4 gene polymorphisms are related to susceptibility to generalized aggressive periodontitis (GAgP). A total of 245 subjects were included in the present study. Genomic DNA was obtained from the peripheral blood of 90 patients with GAgP and 155 periodontally healthy subjects. Probing depth, clinical attachment loss, plaque accumulation, and bleeding on probing were recorded. The TLR2 gene Arg753Gln and Arg677Trp polymorphisms and TLR4 gene Asp299Gly and Thr399Ile polymorphisms were genotyped by the polymerase chain reaction-restriction fragment length polymorphism method. The data were analyzed by chi2 and Mann-Whitney U tests and logistic regression analysis. There was no significant difference in the distribution of TLR2 and TLR4 genotypes and allele frequencies between GAgP patients and healthy subjects (P > 0.05). The TLR2 753Gln allele was found in 3.9% of the GAgP patients compared to 6.1% in the healthy group. The GAgP patients and healthy subjects did not show homozygosity for the TLR2 mutant alleles. The TLR2 677Trp mutant allele was not found in any of the subjects; 2.2% of the GAgP patients and 2.9% of the periodontally healthy subjects were identified as having the TLR4 299Gly polymorphic allele. With regard to the TLR4 399Ile polymorphic allele, 1.1% of the GAgP patients and 2.3% of the periodontally healthy subjects had this allele. The present study failed to find any significant association between the TLR polymorphisms and GAgP, potentially because of the small sample size. To the best of our knowledge, this was the first study to examine the prevalence of these polymorphisms in a Turkish population with aggressive periodontitis.

Has Toll-Like Receptor 4 Been Prematurely Dismissed as an Inflammatory Bowel Disease Gene? Association Study Combined With Meta-Analysis Shows Strong Evidence for Association

Published association studies of the TLR4 Asp299Gly polymorphism and inflammatory bowel disease (IBD) in caucasian populations have inconsistent results. We tested two TLR4 variants for association with IBD in the New Zealand caucasian population and assessed the cumulative evidence for association of TLR4 Asp299Gly and IBD. The TLR4 Asp299Gly and Thr399Ile polymorphisms were genotyped and tested for case-control frequency differences in a New Zealand white cohort of 389 Crohn's disease (CD) patients, 405 ulcerative colitis (UC) patients, and 416 population controls. Meta-analysis using a random effects model was performed to test whether 299Gly carriage was associated with UC, CD, or phenotypes of CD patients. There were no significant allele or genotype frequency differences between cases and controls or between CD phenotypes in our New Zealand data. Meta-analysis did not identify any significant associations between CD phenotypes and 299Gly carriage. However, meta-analysis demonstrated significantly higher 299Gly carrier frequencies in CD patients (odds ratio 1.45, 95% CI 1.11-1.90) and in IBD patients (odds ratio 1.36, 95% CI 1.01-1.84) compared to controls. The meta-analysis provides evidence that Asp299Gly is associated with CD and IBD in whites. Only the Asp299Gly polymorphism has been consistently genotyped in previous TLR4 studies with IBD patients, therefore other TLR4 variants with stronger associations with IBD may exist. Additional well-powered studies of Asp299Gly and other TLR4 variants are urgently needed.

Association Between Toll-Like Receptor Polymorphisms and the Outcome of Liver Transplantation for Chronic Hepatitis C Virus

Experimental models suggest that immune cells recognize hepatitis C virus (HCV) through toll-like receptor (TLR)-2 and TLR4. We assessed the association between the single nucleotide polymorphism in genes that encode for these receptors and the outcome of liver transplantation for chronic HCV. A historical cohort of 92 liver transplant patients with chronic HCV were screened for TLR2 Arg753Gln and TLR4 Asp299Gly and Thr399Ile polymorphisms. The results were correlated with the predefined composite primary outcome of cirrhosis, retransplantation, and death. Statistical analysis was performed using Kaplan-Meier estimation and Cox proportional hazard model. The mean patient age was 49+/-9 years. Sixty percent were male and 84% were white. Twelve (13%) patients had TLR2 Arg753Gln and 32 (35%) had TLR4 Asp299Gly and/or Thr399Ile polymorphism. During the mean follow-up period of 32 months after liver transplantation, the composite primary outcome occurred in 19 (24%) of 80 patients without TLR2 polymorphism, one (14%) of seven patients with heterozygous TLR2 polymorphism, and in all five (100%) patients with homozygous TLR2 polymorphism (P=0.0007). Time-to-event analysis showed a significant association between homozygous TLR2 polymorphism and the primary outcome (P<0.0001). After adjusting for donor age and azathioprine use, homozygous TLR2 mutation (RR 5.20 [1.65-13.9]; P=0.007) remained associated with the primary outcome. TLR4 polymorphisms were not associated with primary outcome. Homozygous TLR2 Arg753Gln polymorphism is associated with allograft failure and mortality after liver transplantation for chronic HCV. The potential clinical relevance of this observation should encourage studies to assess its biologic mechanism.

Association of TLR4 Polymorphisms with Symptomatic Respiratory Syncytial Virus Infection in High-Risk Infants and Young Children

Respiratory syncytial virus (RSV) is a leading cause of infant mortality worldwide. Although anti-RSV Ab prophylaxis has greatly reduced infant mortality in the United States, there is currently no vaccine or effective antiviral therapy. RSV fusion (F) protein activates cells through TLR4. Two single nucleotide polymorphisms (SNPs) encoding Asp299Gly and Thr399Ile substitutions in the TLR4 ectodomain were previously associated with TLR4 hyporesponsiveness and increased susceptibility to bacterial infection. Prevalence of these SNPs was analyzed in a case series of 105 DNA samples extracted from archived nasal lavage samples from high-risk infants/young children with confirmed RSV disease who participated in two seminal clinical trials for anti-RSV prophylaxis. Frequencies of TLR4 SNPs in the case series were compared with those of literature controls, healthy adults, infants, and young children who presented with symptoms of respiratory infections (but not preselected for high risk for RSV). Both SNPs were highly associated with symptomatic RSV disease in this largely premature population (p < 0.0001), with 89.5% and 87.6% of cases being heterozygous for Asp299Gly and Thr399Ile polymorphisms versus published control frequencies of 10.5% and 6.5%, respectively. The other two control groups had similarly low frequencies. Our data suggest that heterozygosity of these two extracellular TLR4 polymorphisms is highly associated with symptomatic RSV disease in high-risk infants and support a dual role for TLR4 SNPs in prematurity and increased susceptibility to RSV not revealed by analysis of either alone.

Lack of association between chronic periodontitis and the Toll‐like receptor 4 gene polymorphisms in a Czech population

Periodontitis is a bacterially induced chronic inflammatory disease and a major cause of tooth loss among adults. Toll-like receptors are signal molecules essential for the cellular response to bacterial cell wall components. The aim of this study was to investigate relationships between chronic periodontitis and variations in the TLR4 gene. A total of 171 patients with chronic periodontitis and 218 unrelated controls were genotyped for the Asp299Gly (896A>G) and Thr399Ile (1196C>T) polymorphisms of the TLR4 gene. Both variants were in nearly complete linkage disequilibrium. No homozygotes for the less common alleles, 299Gly and 399Thr, respectively, were found. The prevalence of the Asp299Gly and the Thr399Ile heterozygotes was 5.3% and 5.0% in controls, and 7.0% and 7.0% in periodontitis patients. In conclusion, TLR4 gene polymorphisms were not significantly associated with the susceptibility to, or severity of, chronic periodontitis in our population.

Toll-like receptor and antiphospholipid mediated thrombosis: in vivo studies

Objective:A study was undertaken to investigate the in vivo pathogenic role of Toll-like receptor 4 (TLR-4) in the antiphospholipid syndrome (APS) by studying the thrombogenic antiphospholipid (aPL) activity in lipopolysaccharide...

Genotypic analysis of Asp299Gly and Thr399Ile polymorphism of Toll-like receptor 4 in systemic autoimmune diseases of Korean population

Dear Editor, Systemic autoimmune diseases such as rheumatoid arthritis and systemic lupus erythematosus are mainly characterized by chronic inXammation ampliWed by large quantities of proinXammatory cytokines released from immune cells including macrophages and dendritic cells. Although the pathogenesis of autoimmune diseases are largely unknown, adaptive immune responses in various systemic autoimmune diseases can be driven by innate immune system as exempliWed in pathogenic autoantibody production triggered by infectious agents in the pathogenesis of rheumatoid arthritis and systemic lupus erythematosus [1, 2]. Toll-like receptors (TLRs) are phylogenetically conserved receptors expressed on various cells, mainly on macrophages and dendritic cells that recognize pathogen-associated molecular patterns and are key players in cellular innate immunity with an emerging role as a bridge between innate and adaptive immune responses [3]. TLRs, especially TLR4, are predominantly activated by bacterial lipopolysaccharides [4] and by endogenous ligands such as heat shock proteins [5], fragments of hyaluronic acid [6] and Wbronectin [7], which are released by damaged cells. Activation of TLRs Wnally leads to activation of nuclear transcription factors such as NFB via signal transduction involving various intracellular signaling systems and to expression of various inXammatory cytokines. There are two variants of TLR4 gene, Asp299Gly and Thr399Ile; both are present in a putative coreceptor-binding region of TLR-4 and in linkage disequilibrium [8]. The polymorphisms at these two TLR4 variants appeared to be correlated with the susceptibility to gram-negative septic shock [9], the development of atherosclerosis [10] and ischemic stroke [11], and with the host susceptibility to autoimmune process in human [12, 13]. Therefore, aberrant TLR functions, especially TLR4 involved in host defense against Gram-negative bacteria, may alter the response of this receptor to stimulation with LPS and probably endogenous ligands and eventually may induce the loss of self-tolerance and triggering of autoimmune diseases. The expression and function of TLR4 in systemic autoimmune diseases have been studied by diVerent groups, but the frequencies of variant alleles and the clinical signiWcance were diVerent depending on diagnosis or on race [9–14]. The frequencies of TLR4 gene polymorphism in these two alleles among Korean population, is not known. Therefore, we report the frequencies of TLR4 Asp299Gly and Thr399Ile polymorphism in E.-S. Kang Division of Diagnostic Immunology, Department of Laboratory Medicine, Ewha Womans University Mokdong Hospital, College of Medicine, Ewha Womans University, Mokdong, Yangcheongu, Seoul 135-710, South Korea

A stop codon polymorphism of toll-like receptor 5 is associated with a stable course of chronic obstructive lung disease

The etiology of chronic obstructive lung disease (COPD) is unclear. It is supposed to be the product of an exogenous antigenic stimulus, such as tobacco smoke, and an endogenous genetic susceptibility. Toll-like receptors (TLR) are signal molecules, essential for the cellular response to bacterial cell wall components. Lipopolysaccharide (LPS) binds to TLR4 and two different polymorphisms for the TLR4 gene (Asp299Gly and Thr399Ile) have recently been described. TLR5 is the receptor for flagellin, aconstituent of Gram-positive and -negative bacterial flagella. A functional relevant TLR5 polymorphism (TLR5392STOP) has already been identified. The coactivation of both TLR4 and 5 seems to play an important role in the mediation of host-defense mechanisms. We genotyped 138 Caucasian patients with COPD and 135 healthy controls for the TLR5 polymorphism TLR5392STOP respectively for Asp299Gly and Thr399Ile polymorphisms in theTLR4gene. Among COPD patients the prevalence for the TLR5 mutant allele was 9.42% (26/276). The prevalence for each Asp299Gly and Thr399Ile mutant allele was 4.71% (13/276). In the control group the TLR5 mutation prevalence was 5.19% (14/270) (P = 0.138), the prevalence of each TLR4 polymorphism was 2.96% (8/270) (p = 0.279). In the subgroup of 54 patients with a stable course of COPD, defined as less than three hospitalizations over the last three years due to COPD, we found a significant association with the TLR5392STOP gene polymorphism (P = 0.026). These data suggest that the TLR5392STOP polymorphism is associated with a stable course of COPD, whereas TLR4 polymorphisms have no impact neither on the onset nor on the course of COPD.

Lack of genetic association of the Toll-like receptor 4 (TLR4) Asp299Gly and Thr399Ile polymorphisms with spondylarthropathies in a Hungarian population

Bacteria have long been suggested as aetiological factors in the genetically susceptible host in spondylarthropathies, including ankylosing spondylitis (AS) and reactive arthritis (ReA). Variability of the Toll-like receptor 4 (TLR4) gene has been shown to play a role in the inflammatory response to certain bacterial infections. We investigated whether TLR4 Asp299Gly and Thr399Ile polymorphisms contribute to the genetic background of spondylarthropathies in a cohort of Hungarian patients with AS and ReA. DNA was obtained from patients with AS (n=138), ReA (n=91) and ethnically matched healthy controls (n=140). Genotyping was carried out by polymerase chain reaction-restriction fragment length polymorphism analysis and the results were confirmed by direct sequencing. No significant differences in allele or genotype frequencies were observed between controls and either the AS patients or the ReA patients. Clinical characteristics of these groups were unrelated to the presence of any of these polymorphisms. Toll-like receptor 4 Asp299Gly and Thr399Ile polymorphisms do not contribute to disease susceptibility in either AS or ReA. Functional abnormalities of the TLR4 signalling pathway suggested in spondylarthropathies seem not to be genetically determined by these two common polymorphisms.

Microsatelite GT polymorphism in the toll‐like receptor 2 is associated with colorectal cancer

Factors underlying genetic predisposition for development of sporadic colorectal cancer are largely unknown. The fact that this cancer is more common in patients suffering from inflammatory bowel disease raises the question of the relationship between chronic inflammation and cancer. Toll-like receptors 2 (TLR2) and 4 (TLR4) are critical in initiating innate immune response and inflammation toward various bacteria commonly found in the intestine. Recent evidence about the association of polymorphisms in these genes with ulcerative colitis and Crohn's disease, as well as other inflammatory conditions, was the basis for our investigation of their role in sporadic colorectal cancer. We assessed genotype and allele frequencies of TLR2 GT microsatelite polymorphism, TLR2 Arg753Gln, TLR4 Asp299Gly and TLR4 Thr399Ile polymorphisms in 89 colorectal cancer patients and 88 age- and sex-matched controls. The frequency of TLR2 GT microsatelite alleles with 20 and 21 GT repeats was decreased (p = 0.0044 and p = 0.001, respectively), while the frequency of the allele with 31 GT repeats was increased (p = 0.0147) in patients. The mutant allele Asp299Gly of TLR4 gene was slightly more frequent in colorectal cancer patients (p = 0.0269). In conclusion, we report an association of microsatelite GT polymorphisms of TLR2 gene and Asp299Gly polymorphism of the TLR4 gene with sporadic colorectal cancer among Croatians.