TLR4 Asp299Gly Polymorphisms Research Articles

Toll-like receptor 4 gene polymorphism modulates phenotypic expression in patients with hereditary hemochromatosis

Clinical penetrance of hereditary hemochromatosis is highly variable. We hypothesized that it might be modified by factors involved in the cellular immune response, such as toll-like receptors (TLRs) or nucleotide oligomerization domain proteins (NODs). Clinical expression of hemochromatosis was assessed as a function of TLR4, TLR9, and NOD2 polymorphisms in 99 homozygous carriers of the HFE C282Y mutation with mild-to-severe iron overload. Thirteen (13%) of the 99 hemochromatosis patients were heterozygous for a TLR4 Asp299Gly polymorphism and 86 (87%) were TLR4 wild-type-only carriers. Clinical expression of hemochromatosis was observed more frequently in carriers of the TLR4 polymorphism (100%) than in TLR4 wild-type carriers (56%, P = 0.002). This was based on higher prevalences of liver disease (92 vs. 45%, P = 0.002) and arthropathy of metacarpophalangeal joints (69 vs. 35%, P = 0.018) in TLR4 polymorphism carriers. The finding was strengthened by the strong association of TLR4 polymorphism with liver fibrosis in the subgroup of 52 patients who underwent a liver biopsy (P = 0.011). The TLR4 polymorphism did, however, not correlate with body iron overload. The study results remained significant in multiple regression analyses after excluding possible confounding effects, such as age, sex, alcohol, or meat intake, and in the subgroup of 84 patients presenting as the first members of their families. TLR4 Asp299Gly polymorphism modulates clinical expression in patients with hereditary hemochromatosis. The polymorphism does not correlate with iron overload suggesting that TLR4 plays a role in an inflammatory process arising from toxic effects of iron accumulation.

Toll‐like receptor 4 Asp299Gly polymorphism in respiratory syncytial virus epidemics

The respiratory syncytial virus (RSV) antigen serves as ligand for Toll-like receptor (TLR) 4 that is a transmembrane signaling receptor in macrophages and dendritic cells. According to current evidence single nucleotide polymorphism involving amino acid 299 influences the susceptibility to severe RSV infections. The Asp299Gly allele has been shown to influence the TLR4-mediated signaling causing conformational change in the extracellular domain that recognizes pathogen-associated molecular patterns. The aim was to study the association between the TLR4 Asp299Gly polymorphism and the susceptibility to severe RSV bronchiolitis in infants. Altogether 312 cases and 356 controls, selected on the basis place of residence, date of birth, gender, and gestation at birth, were studied. When adjusted for multiple dependent variables, no allele or genotype frequency difference was found between the cases and the controls. Post hoc analysis revealed that during the year 2000 epidemics, the Gly299Gly genotype associated with protection against severe RSV and during 2004 epidemics Gly299Gly genotype and 299Gly allele associated with severe RSV. To conclude, we could not confirm the association of the Gly299 allele with severe RSV. This is consistent with the evidence that the susceptibility to severe RSV infection is principally dependent on environmental and constitutional factors. We propose that the risk of severe RSV infection may additionally depend on the interaction between individual TLR4 genotype and the particular RSV group causing bronchiolitis.

Toll-like receptor gene polymorphisms and susceptibility to inflammatory bowel disease in Chinese Han and Caucasian populations

To explore the distribution of Toll-like receptors gene polymorphisms in inflammatory bowel disease (IBD) in Chinese Han patients and Caucasians. The toll-like receptor 2 (TLR2) genes Arg677Trp and Arg753Glu, TLR4 genes Asp299Gly and Thr399Ile, and TLR9 gene 1237T/C polymorphisms were genotypes in 113 patients with IBD and 120 age and gender-matched healthy controls by the analyses of polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). A meta-analysis was performed to test whether TLR4 Asp299Gly and Thr399Ile polymorphisms were associated with ulcerative colitis (UC) or Crohn's disease (CD) susceptibility and whether 299Gly carriage was associated with phenotypes of CD patients in the Caucasian population. We found two carriers of TLR9 1237C in UC patients, one carrier in CD patients and one in healthy controls respectively (CD: P = 0.361; UC: P = 0.569). There was no statistically significant difference in both allelic and genotypic frequencies. The mutant genotypes of TLR2 gene Arg677Trp and Arg753Glu, TLR4 gene Asp299Gly and Thr399Ile were not found in either the IBD patients or the healthy controls. The TLR4 299G allele showed a significant association with CD and UC in Caucasian population (OR = 1.29, 95%CI: 1.08 - 1.54, P = 0.004 and OR = 1.28, 95%CI: 1.08 - 1.51, P = 0.004 respectively). Similar association was detected between T399I polymorphism and susceptibility to IBD (OR = 1.37, 95%CI: 1.12 - 1.68, P = 0.002 and OR = 1.46, 95%CI: 1.13 - 1.88, P = 0.003 respectively). However, no significant association was identified between CD phenotypes and 299Gly carriage. TLR2 genes Arg677Trp and Arg753Glu, TLR4 genes Asp299Gly and Thr399Ile and TLR9 gene 1237T/C polymorphisms are not associated with IBD in Chinese Han patients. In Caucasians, both TLR4 299G and 399I confer a significant risk for developing CD and UC. The contribution of genetic determinants may differ significantly between ethnicities.

S1641 Impact of the TLR4 Asp299Gly Polymorphism on Induction of the Inflammatory Response Following H. pylori Infection

S1641 Impact of the TLR4 Asp299Gly Polymorphism on Induction of the Inflammatory Response Following H. pylori Infection

OC-048 Impact of the TLR4 Asp299gly polymorphism on induction of the inflammatory response followingHelicobacter pyloriinfection

<h3>Introduction</h3> The TLR4 Asp299Gly polymorphism causes immune dysregulation and is associated with unfavourable outcome in <i>H pylori</i> induced gastric cancer. It has been suggested that the polymorphism exerts effects through post-receptor signalling, more readily recruiting TRAM and inducing type I interferon production as opposed to Mal recruitment which activates NF-κB and pro-inflammatory cytokine production. <h3>Methods</h3> Peripheral blood monocytes were isolated from individuals with and without the TLR4 Asp299Gly polymorphism. <i>H pylori</i> LPS was added to the cells and incubated for up to 6 h. RNA was extracted from monocytes and cDNA was synthesised and expression assessed in TLR4 signalling pathway genes. Activation of intermediate signalling steps in the Mal and TRAM pathways were assessed by western blot. <h3>Results</h3> NF-κB gene expression in Asp299Gly polymorphism carriers was elevated after 2–4-h LPS stimulation compared to wildtype individuals. This delayed NF-κB gene expression in carriers of the polymorphism coincided with increased expression of components of the MyD88 independent pathway including IFN-β. <h3>Conclusion</h3> The TLR4 Asp299Gly polymorphism influences downstream signalling and adaptor protein recruitment following LPS stimulation. Carriers of the polymorphism have increased expression of components of the Tram pathway. It is plausible that during <i>H pylori</i> infection, the TLR4 Asp299Gly polymorphism modulates LPS mediated inflammation which directly impacts on clinical outcome in <i>H pylori</i> infection.

The TLR4 ASP299GLY Polymorphism is a Risk Factor for Active Tuberculosis in Caucasian HIV-Infected Patients

Tuberculosis (TB) is a pandemic infectious disease especially frequent in HIV-infected patients. Toll-like receptor (TLR) 4 has been described to play a main role in the innate immunity against TB. In fact, single nucleotide polymorphisms (SNPs) in TLRs may influence AIDS disease progression. The association between two particular SNPs in human TLR4 (Asp299Gly and Thr399Ile) and active TB has been studied in non-HIV Africans with contradictory results. However, studies focusing on the effect of these TLR4 SNPs in active TB within a Caucasian HIV population are lacking. To analyze the association between TLR4 Asp299Gly and Thr399Ile SNPs and active TB, in Caucasian Mediterranean HIV-infected individuals. 468 HIV-infected patients were analyzed. TLR4 genotyping was performed by real-time PCR and melting curve technology. TB was diagnosed in 59 (12,6%) patients. In a bivariate analysis several variables resulted significantly associated with active TB; intravenous drugs use (OR= 2.2; 95% CI [1.2-3.8]), hepatitis C virus (HCV) co-infection (OR= 3.4; 95% CI [1.6-7.1]), CD4 count (p<0.001), HIV viral load (p=0.003), latent TB prophylaxis (OR= 0.3; 95% CI [0.1-0.5]), and TLR4 Asp299Gly (OR= 2.0; 95% CI [1.1-4.2]). No statistical association was found for the TLR4 Thr399Ile. After a multivariate analysis, HCV co-infection (OR= 3.8; 95% CI [2.2-6.5]), baseline CD4 count (OR= 0.996; 95% CI [0.994-0.998]), TLR4 Asp299Gly (OR= 2.57; 95% CI [1.18-5.61]) were independently associated with active TB and inversely with latent TB prophylaxis (OR= 0.24; 95% CI [0.01-0.60]). We describe an independent association between TLR4 Asp299Gly SNP and active TB in Caucasian Mediterranean HIV-infected patients.

The functional Toll-like receptor 4 Asp299Gly polymorphism is associated with lower left ventricular mass in hypertensive women

Background This study investigated the impact of a putative functional TLR4 polymorphism (Asp299Gly) on left ventricular (LV) structure in hypertensive subjects. Methods A sample of 443 patients (266 women and 177 men) was evaluated by clinical history, physical examination, anthropometry, analysis of inflammatory and metabolic parameters, echocardiography and TLR4 Asp299Gly genotyping. In addition, the relationship between the polymorphism and in vitro lipopolysaccharide responsiveness of peripheral blood monocytic cells was also assessed. Results Women carrying the 299Gly allele presented lower posterior wall thickness ( p = 0.01), interventricular septum thickness ( p = 0.04), LV mass ( p = 0.01) and LV mass index ( p = 0.03), as well as a reduced prevalence of LV hypertrophy ( p = 0.002), in comparison to women with the wild-type genotype. These results were confirmed by stepwise and logistic regression analyses adjusted for potential confounders. Conversely, the 299Gly allele did not influence LV structure in men. Furthermore, in vitro assays revealed that monocytes of either men or women heterozygous for the 299Gly allele presented a lower lipopolysaccharide-induced production of interleukin-6, compared to non-carriers. Conclusions The functional TLR4 Asp299Gly polymorphism is associated with lower LV mass in hypertensive women. These findings suggest that interactions among gender, LV remodeling and TLR4 gene variants may occur in hypertensive subjects.

Association between IL-18gene polymorphisms and biopsy-proven giant cell arteritis

IntroductionThe objective was to investigate the potential implication of the IL18 gene promoter polymorphisms in the susceptibility to giant-cell arteritis (GCA).MethodsIn total, 212 patients diagnosed with biopsy-proven GCA were included in this study. DNA from patients and matched controls was obtained from peripheral blood. Samples were genotyped for the IL18-137 G>C (rs187238), the IL18-607 C>A (rs1946518), and the IL18-1297 T>C (rs360719) gene polymorphisms with polymerase chain reaction, by using a predesigned TaqMan allele discrimination assay.ResultsNo significant association between the IL18-137 G>C polymorphism and GCA was found. However, the IL18 -607 allele A was significantly increased in GCA patients compared with controls (47.8% versus 40.9% in patients and controls respectively; P = 0.02; OR, 1.32; 95% CI, 1.04 to 1.69). It was due to an increased frequency of homozygosity for the IL18 -607 A/A genotype in patients with GCA (20.4%) compared with controls (13.4%) (IL18 -607 A/A versus IL18 -607 A/C plus IL18 -607 C/C genotypes: P = 0.04; OR, 1.59; 95% CI, 1.02 to 2.46). Also, the IL18-1297 allele C was significantly increased in GCA patients (30.7%) compared with controls (23.0%) (P = 0.003; OR, 1.48; 95% CI, 1.13 to 1.95). In this regard, an increased susceptibility to GCA was observed in individuals carrying the IL18-1297 C/C or the IL18-1297 C/T genotypes compared with those carrying the IL18-1297 T/T genotype (IL18-1297 C/C plus IL18-1297 T/C versus IL18-1297 T/T genotype in GCA patients compared with controls: P = 0.005; OR, 1.61; 95% CI, 1.15 to 2.25). We also found an additive effect of the IL18 -1297 and -607 polymorphisms with TLR4 Asp299Gly polymorphism. The OR for GCA was 1.95 for combinations of genotypes with one or two risk alleles, whereas carriers of three or more risk alleles have an OR of 3.7.ConclusionsOur results show for the first time an implication of IL18 gene-promoter polymorphisms in the susceptibility to biopsy-proven GCA. In addition, an additive effect between the associated IL18 and TLR4 genetic variants was observed.

Association of TLR4 Asp299Gly and Thr399Ile polymorphisms with Guillain-Barré syndrome in Northern Indian population

Molecular mimicry between Campylobacter jejuni lipopolysaccharide and host gangliosides induces an immune response leading to axonal damage and Guillain-Barré syndrome (GBS). TLR polymorphisms are associated with many autoimmune diseases. The role of the TLR4 gene in GBS susceptibility largely remains unknown. We investigated TLR4 polymorphism in GBS. One hundred and twenty GBS patients and 150 healthy controls were included. TLR4 (Asp299Gly and Thr399Ile) genes were studied by PCR-RFLP. TLR4 (Asp299Gly) polymorphism was significantly associated with GBS ( p, 0.045; OR, 8.75; 95% CI, 1.05–72.88); only acute motor axonal neuropathy (AMAN) was associated with Gly299Gly homozygote ( p, 0.027; OR, 12.40; 95% CI, 1.33–115.77) and Thr399Ile ( p, 0.019; OR, 3.42; 95% CI, 1.22–9.54) heterozygote, and TLR4–399Ile allele ( p, 0.045; OR, 2.63; 95% CI, 1.02–6.75) compared to controls. In conclusion, TLR4 (Asp299Gly) polymorphism is associated with an increased susceptibility to GBS. Besides Asp299Gly, AMAN subtype is also associated with Thr399Ile polymorphism.

Association of the TLR4 Asp299Gly polymorphism with lung function in relation to body mass index

BackgroundPrevious studies have shown conflicting results for the association between TLR4 polymorphism (Asp299Gly) and lung function. We investigated the influence of TLR4 Asp299Gly, a polymorphism, on lung function in a community population.MethodsIn 2003, a cross-sectional survey was conducted to assess the respiratory health of residents living in and around the town of Humboldt, Saskatchewan, Canada. There were 2090 adults age 18-79 years who completed a questionnaire that included a medical and smoking history, as well as socio-economic and lifestyle variables. Genetic information and lung function test measurements were available on 1725 subjects (754 males and 971 females) of the 2090 respondents. These subjects were selected for further analysis to investigate the association between TLR4 Asp299Gly genotype and forced expiratory volume in the first second in liters (FEV1), forced vital capacity in liters (FVC), FEV1/FVC ratio, and forced expiratory flow rate in liters/second (FEF25-75). Multivariable linear regression analysis was used to investigate associations.ResultsAdjusted mean values of FEV1 and FVC were significantly different between TLR4 wild type and TLR4 variant groups [Mean ± S.E.: (TLR4 wild type - FEV1: 3.18 ± 0.02, FVC: 3.95 ± 0.03; TLR4 variant - FEV1: 3.31 ± 0.06, FVC: 4.14 ± 0.07)]. Based on multivariable regression analysis, we observed that body mass index (BMI) was associated with decreased FEV1/FVC ratio and FEF25-75 in TLR4 variant group but not in wild type group.ConclusionBMI may modify the associations of TLR4 Asp299Gly polymorphism with FEV1/FVC ratio and FEF25-75.

Identification of polymorphisms in the Toll-like receptor gene and the association with allergic rhinitis

The TLRs gene encodes the principal innate immunity receptor in humans. The TLR2 Arg753Gln and Arg677Trp polymorphisms have been associated with a reduced response of monocytes and cell lines to challenge with mycobacteria. The TLR4 Asp299Gly and Thr399Ile polymorphisms have been associated with a reduction in the inflammatory responses to lipopolysaccharide in humans. It has been suggested that TLR2 and TLR4 polymorphisms may be associated with allergic responses; thus, we hypothesized that TLR2 and TLR4 polymorphisms may modify the relative risk for development of allergic rhinitis. The Taqman assay and high-resolution melt (HRM) were used for genotyping. We analyzed two single nucleotide polymorphisms (SNPs; 597T>C and 1350T>C) in the TLR2 gene and 1 SNP (4216G>C) in the TLR4 gene. We compared the genotype of these SNPs in patients with allergic rhinitis and controls without allergic rhinitis. We also estimated the haplotype frequencies between the two groups. The genotype and allele frequencies of the 597T>C and 1350T>C SNPs in the TLR2 gene were not significantly different between the patients with allergic rhinitis and controls (P > 0.05). The genotype and allele frequencies of 4216G>C in the TLR4 gene were not significantly different between the patients with allergic rhinitis and controls (P > 0.05). Haplotype analysis of the following two different (597)-(1350) major haplotypes (frequency >0.05) were present in the TLR2 gene: T-C and C-C. The C-C haplotype was positively associated with allergic rhinitis (P = 0.048). Our study suggests that the TLR2 gene polymorphisms might be susceptible to the development of allergic rhinitis. Further functional studies of TLR2 genetics in light of the associations with allergic rhinitis inflammation would help clarify the role of TLR2 genetics in clinical evaluations.

TLR-2 Arg753Gln, TLR-4 Asp299Gly, and TLR-4 Thr399Ile polymorphisms in Henoch Schonlein purpura with and without renal involvement

Infections may trigger or aggravate glomerulonephritidis and renal vasculitis like Henoch Schonlein purpura (HSP). HSP is seen more frequently in patients with familial Mediterranean fever in which TLR-2 Arg753Gln polymorphism frequency is increased. Although renal involvement is the most important factor affecting the prognosis in HSP, it is not known which patients will have renal disease or why some patients have severe renal involvement while some others have mild renal disease. We investigated the role of TLR-2 and TLR-4 polymorphisms on the incidence and severity of renal involvement in HSP patients. We studied HSP patients with and without nephritis (n = 15 for each group) and healthy controls (n = 100). TLR-2 Arg753Gln and TLR-4 Asp299Gly/Thr399Ile polymorphisms were analyzed with polymerase chain reaction-restriction fragment length polymorphism method. The frequency of TLR-2 Arg753Gln, TLR-4 Asp299Gly, and Thr399Ile polymorphisms in healthy controls were 1, 3, and 2%, respectively. The frequencies of these polymorphisms were not different in HSP patients with or without nephritis compared to healthy controls. TLR-2 Arg753Gln, TLR-4 Asp299Gly, and Thr399Ile polymorphisms are not increased in HSP or HSP nephritis patients.

Evaluation of the polymorphism in the Toll-like receptor 4 (TLR4) genes of tympanosclerosis patients

Objective Although eardrum perforations which endure etiopathogenesis for a long-time and middle ear infections are proposed for causing the tympanosclerosis (TS), tympanosclerosis emerges in some chronic otitis media (COM), some of them do not appear although a continuing COM and enduring perforation last. In this study, the effect of the molecular reasons which display genetic differences in TS formation is evaluated; our aim is to determine the Asp299Gly polymorphism frequencies in the TLR4 gene of patients with TS who have COM, and patients who do not. Materials and methods Patients who have undergone COM surgery, were divided into two groups of 50 persons who were selected in accordance with the fact, whether they had TS in their middle ear cavity or not during operation. 100 healthy persons who had similar demographic data, were evaluated as the control group. The DNA isolation was executed by using standard methods with peripheric blood specimen of the diseased group and control group. The Restriction Fragment Length Polymorphism method was used in determining the Asp299Gly allel in the TLR4 gene. Items of 249 bc for the wild tip (Asp) post-restriction enzyme segment wild tip (Asp) allel, and 23 bc and 196 bc post-restriction enzyme segment polymorphic allel (Gly) were obtained. Results TLR4 Asp299Gly polymorphism (10%) was asserted in a total of five specimens in the diseased group with TS. TLR4 Asp299Gly polymorphism was found positive in only one (2%) of the 50 phenomenons in the group without TS. TLR4 Asp299Gly polymorphism was found positive in six (6%) of the 100 phenomenons in the control group. The positive polymorphism in phenomenons with TS was significant in accordance with statistics, when compared with the group without TS ( p < 0.05). However, although the polymorphism rates were higher than the rates of the control group, it was not statistically significant ( p > 0.05). Conclusion TS may not appear in many patients who had undergone middle ear infection, and had perforation for many years. The polymorphism in arteriosclerosis in the TLR4 gene which caused the inflammatory cytokines oscillation recognize the bacterial LPS, was also accused. It is engrossing to find out from the results of our study on a restricted number of patients, and on only one gene, that molecular reasons which display genetic differences can also be effective in forming TS. Serial researches of greater dimensions are required.

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.

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.

S2089 A Loss-of-Function Anionic Trypsinogen (PRSS2) Variant in Japanese Patients with Pancreatic Diseases

PCR-restriction fragment length polymorphism and the Genescan analyses: GT microsatellite polymorphism in the TLR2 gene, Asp299Gly in the TLR4 gene, -260C/T and -550C/T polymorphisms in the CD14 gene. For the TLR2 GT microsatellite polymorphism, we classified alleles into two subclasses, 12-16 GT repeats (S allele) and 17-28 repeats (L allele). Statistical analysis was performed using the Fisher's exact test. Results : The frequencies of the S allele of the TLR2 GT microsatellite polymorphism, the T allele of -260 C/T, and C allele of CD14 -550 C/T were higher in patients with AP (p=0.0006 for the S allele TLR2 GT polymorphism, p = 0.0147 for the -260 T allele, and p = 0.0292 for -550 C allele). No TLR4 Asp299Gly polymorphism was found. The frequency of S allele in the TLR2 GT microsatellite polymorphism was higher in patients with severe AP than those with mild AP. For the other polymorphisms, no differences were observed in subgroups based on severity or etiology of pancreatitis. None of the polymorphisms examined showed significant difference in the distribution of genotypes or alleles between the patients with and without bacterial infection. Conclusions : TLR2 intron 2 GT repeats, CD14 -260 C/T and CD14 -550 C/T polymorphism are associated with AP in Japan.

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.

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.

TLR2 Arg753Gly, TLR4 Asp299Gly and Thr399Ile gene polymorphisms are not associated with chronic periodontitis in a Turkish population

Toll-like receptor (TLR) gene polymorphisms could affect the host's ability to respond to microbial pathogens. In this case-control study, the association of TLR2 and TLR4 gene polymorphisms with chronic periodontitis (CP) was investigated. Genomic DNA was obtained from the peripheral blood of 83 patients with CP and 106 periodontally healthy subjects. The TLR2 Arg753Gly, Arg677Trp and TLR4 Asp299Gly, Thr399Ile gene polymorphisms were genotyped by the polymerase chain reaction-restriction fragment length polymorphism method. The data were analysed by a chi2 test, logistic regression analysis and the Mann-Whitney U test. The 753Gln allele was found in 6.1% of the CP patients as compared with 6.6% in the control group (p>0.05). The frequency of the 299Gly and 399Ile allele was 2.4% and 1.8% in CP patients. For the healthy subjects, the frequency was 2.8% for the 299Gly and 2.5% for the 399Ile allele (p>0.05). None of the CP patients or healthy subjects showed homozygosity for the TLR2 and TLR4 alleles. Percentage of sites with bleeding on probing and plaque were significantly higher in 299Gly-positive patients compared with 299Gly-negative patients (p<0.05). These results showed that the TLR2 and TLR4 gene polymorphisms studied are not associated with susceptibility to CP in Turkish patients.