Polymorphism in the 3' UTR of the IL12B gene is associated with Chagas' disease cardiomyopathy

The aim of this study was to investigate the possible influence of a 3' untranslated region (3' UTR) polymorphism of the IL12B gene in susceptibility to Trypanosoma cruzi infection or in the development to cardiomyopathy in Chagas' disease (CD). We determined the IL12B 3' UTR genotypes in a sample of 200 seronegative individuals and 260 serologically positive patients (130 with Chagasic cardiomyopathy and 130 asymptomatic). All individuals are from a Colombian region where T. cruzi infection is endemic. Genotyping was performed by the PCR-restriction fragment length polymorphism (RFLP) method. The overall distribution of the IL12B 3' UTR alleles and genotypes in seronegative compared with seropositive individuals was not statistically significant. Interestingly, we found that the IL12B 3' UTR CC genotype was significantly increased among cardiomyopathic patients when compared to asymptomatic individuals (16% versus 5%; P=0.005; P(c)=0.015; OR=3.39; 95% CI 1.3-9.15). In addition, we observed that the IL12B 3' UTR C allele was present at significantly higher frequency in cardiomyopathic (33% versus 22%; P=0.008; P(c)=0.016; OR=1.69; 95% CI 1.12-2.55) as compared to asymptomatic. Our results suggest that IL12B 3' UTR gene polymorphisms may influence the susceptibility to develop Chagasic cardiomyopathy.     

Genetic polymorphisms in TNFA/TNFR2 genes and Chagas disease in a Colombian endemic population

In this study we investigated the association of functional single nucleotide polymorphisms of tumor necrosis factor-alfa (TNFA) and TNF receptor 2 (TNFR2) genes in determining the susceptibility to Chagas' disease. This study included 313 patients from Colombia serologically positive for Trypanosoma cruzi antigens (cardiomyopathic, N=159; asymptomatic, N=154). Genotypes were determined by polymerase chain reaction (PCR)-restriction fragment length polymorphism method. We found a significant difference in the distribution of the TNFA -1031C (p=0.0153, OR=1.69, CI=1.10-2.58) and -308A (p=0.0002, OR=2.60, CI=1.53-4.39) alleles between cardiomyopathic and asymptomatic subjects. In addition, we observed that the TNFR2 +676T allele was monomorphic in our population. Our results suggest that TNFA -1031C and -308A gene polymorphisms may influence the susceptibility to develop chagasic cardiomyopathy in the population under study.     

HLA and beta-myosin heavy chain do not influence susceptibility to Chagas disease cardiomyopathy

An inflammatory dilated cardiomyopathy occurs in 30% of Chagas' disease patients, chronically infected by Trypanosoma cruzi, while the remaining infected individuals are asymptomatic. Studies have indicated a role for genetic factors in the susceptibility to Chagas' disease cardiomyopathy. In an attempt to identify the genetic factors influencing the development and outcome of Chagas' cardiomyopathy, we compared the frequencies of alleles from two candidate gene loci, class II HLA and a microsatellite marker for the human cardiac beta-myosin heavy chain gene in different clinical groups. Patients were grouped as asymptomatic or with severe or mild cardiomyopathy. The results indicate that the HLA and myosin microsatellite allele profiles in all cardiomyopathy and in asymptomatic groups are similar. In conclusion, these results establish that polymorphism of HLA-DR and -DQ molecules, as well as beta-cardiac myosin, do not influence the susceptibility to different clinical forms of Chagas' disease or the progression to severe Chagas' cardiomyopathy. On the other hand, male sex was identified as a risk factor for progression to the more severe forms of cardiomyopathy (relative risk = 8.75).     

Toll-like receptor 2 and Toll-like receptor 4 polymorphisms in invasive pneumococcal disease

BACKGROUND: Toll-like receptors (TLRs) recognize distinct pathogen-associated molecular patterns and trigger anti-microbial host defense responses. Several in vitro and in vivo studies in mice indicate that TLR2 and TLR4 are involved in the defense against Streptococcus pneumoniae. Studies have revealed associations between polymorphisms in TLRs and human diseases. The effect of polymorphisms in TLR2 and TLR4 in the human defense to S. pneumoniae has not been studied. METHODS: We genotyped 99 Caucasian patients with invasive pneumococcal disease and 178 Caucasian controls for the known R579H, P631H and R753Q polymorphisms in TLR2 and the D299G polymorphism in TLR4 with PCR-RFLP methods. RESULTS: The distribution of the TLR2 R579H, P631H and R753Q and TLR4 D299G variants was not significantly different between the patients and the controls. After stratification of the patient population by age, sex, diagnosis, and mortality no significant differences for the TLR2 R753Q genotype and TLR4 D299G genotype were found between various patient subgroups and between patient subgroups and the control population. It should be mentioned that for the TLR2 polymorphisms neither the control group nor the patient group contains homozygous mutant individuals. CONCLUSION: We found no association between TLR2 and TLR4 polymorphisms and invasive pneumococcal infection.     

Lack of association of Toll-like receptor 2 Arg753Gln with cutaneous leishmaniasis

The aim of the present study was to investigate the frequency of Arg753Gln and Arg677Trp polymorphisms of TLR2 in patients with cutaneous leishmaniasis (CL) compared to healthy controls. The polymorphisms were genotyped by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) and amplification refractory mutation system assay (ARMS-PCR). The results showed that the frequency of Arg753Gln genotype was 14.3% and 10.1% in CL patients and normal controls, respectively. No one in either group was homozygous for the mutation. There was no significant difference in the genotype frequency. In contrast to the results for Arg753Gln polymorphism, we did not detect any case with Arg677Trp polymorphism in either control or patient group. In conclusion the TLR2 mutations are found equally in CL patients and healthy subjects.     

Association between TLR2 and TLR4 Gene Polymorphisms and the Susceptibility to Inflammatory Bowel Disease: A Meta-Analysis

BackgroundThe associations between toll-like receptor 2 (TLR2) and toll-like receptor 4(TLR4) polymorphisms and inflammatory bowel disease (IBD) susceptibility remain controversial. A meta-analysis was performed to assess these associations.MethodsA systematic search was performed to identify all relevant studies relating TLR2 and TLR4 polymorphisms and IBD susceptibility. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. Subgroup analyses were performed by ethnicity and publication quality.ResultsThirty-eight eligible studies, assessing 10970 cases and 7061 controls were included. No TLR2 Arg677Trp polymorphism was found. No significant association was observed between TLR2 Arg753Gln polymorphism and Crohn’s disease (CD) or ulcerative colitis (UC) in all genetic models. Interestingly, TLR4 Asp299Gly polymorphism was significantly associated with increased risk of CD and UC in all genetic models, except for the additive one in CD. In addition, a statistically significant association between TLR4 Asp299Gly polymorphism and IBD was observed among high quality studies evaluating Caucasians, but not Asians. Associations between TLR4 Thr399Ile polymorphisms and CD risk were found only in the allele and dominant models. The TLR4 Thr399Ile polymorphism was associated with UC risk in pooled results as well as subgroup analysis of high quality publications assessing Caucasians, in allele and dominant models.ConclusionsThe meta-analysis provides evidence that TLR2 Arg753Gln is not associated with CD and UC susceptibility in Asians; TLR4 Asp299Gly is associated with CD and UC susceptibility in Caucasians, but not Asians. TLR4 Thr399Ile may be associated with IBD susceptibility in Caucasians only. Additional well-powered studies of Asp299Gly and other TLR4 variants are warranted.     

Relationship of TLR2 and TLR4 gene polymorphism with a penchant for individual urogenital infections

We investigated the population prevalence of polymorphisms of Arg753Gln TLR2gene, and Asp299Gly, Thr399Ile TLR4 genes among people living in the Poltava region, as well as data communication polymorphisms with the presence of diseases caused by urogenital infections. The group of population control was a random sample of residents of the Poltava region (n = 299). The group of patients with urogenital diseases included 156 people. Genotyping of these groups TLR2 Arg753Gln polymorphism and the gene TLR4 Asp299Gly, Thr399Ile was performed using PCR and subsequent restriction analysis. Statistically significant association of allele A ofgene TLR2 (p = 0.0018) and allele G of gene TLR4 (p = 0.085) with the presence of urogenital diseases was confirmed.     

Toll-like receptor 2 and Toll-like receptor 4 polymorphisms and susceptibility to asthma and allergic rhinitis: a case-control analysis

The aim of the study was to investigate whether polymorphisms in genes encoding Toll-like receptors (TLR2 and TLR4) may modify relative risk for development of asthma or allergic rhinitis. The results showed that the genotype and allele frequencies of the TLR2 Arg753Gln and TLR4 Asp299Gly polymorphisms were not significantly different between asthmatic children or allergic rhinitis when compared to controls (p>0.05 for each) or even when compared further with IgE level. However, it was shown that the mutant allele of TLR2 or TLR4 polymorphisms were significantly associated with the moderate-severe group compared to the mild group in both atopic asthmatics and allergic rhinitis group (p>0.001 for each). In conclusion, our study demonstrates a lack of association of TLR2 and TLR4 polymorphisms with asthma and allergic rhinitis but suggests significant association between these genetic variants and the disease severity.     

Levels of anti-M2 and anti-beta1 autoantibodies do not correlate with the degree of heart dysfunction in Chagas' heart disease

Chronic chagasic cardiomyopathy (CCC) is characterized mainly by a dilated cardiomyopathy complicated by frequent and complex ventricular arrhythmias and/or conduction defects. The aim of the present study was to evaluate functional implications of neurotransmitter receptor autoantibodies in vivo. Sera from chagasic patients were used to measure the level of autoantibodies to peptide fragments from the M2 cholinergic and beta1 adrenergic receptors. Optical density values and the frequency of anti-M2 and anti-beta1 antibodies were significantly higher in the indeterminate form and in CCC patients than in normal individuals. There was no correlation between levels of autoantibodies and clinical parameters of ventricular dysfunction, as assessed by echocardiography. Patients presenting with chronotropic insufficiency in exercise test had higher levels of anti-M2 but not anti-beta1 autoantibodies. Although anti-M2 and anti-beta1 antibodies do not appear to play a role in the pathophysiology of the heart failure that accompanies severe CCC, anti-M2 cholinergic autoantibodies may contribute to the pathogenesis of Chagas' disease dysautonomia.     

Atrial natriuretic factor as marker of myocardial compromise in Chagas' disease

This study investigated the evolution of plasma atrial natriuretic factor (ANF) in patients in different stages of Chagas' disease and analyzed its usefulness as prognostic factor of the development of myocardial compromise in asymptomatic chagasic patients. Chagas' disease, a determinant of heart failure, is caused by the parasite Trypanosoma cruzi. A total of 21 chagasic patients were studied: 9 in the asymptomatic stage, 6 with conduction defects (CD), and 6 with chronic heart failure (CHF); and 31 controls: 16 healthy, 6 with CD, and 9 with CHF. Plasma ANF radioimmunoassay (RIA) and complementary studies were performed twice for each patient, with an interval period of 12 months. First sample: chagasic patients showed higher ANF levels in the CHF group than in CD and asymptomatic subjects; second sample: the peptide levels were higher in CHF patients than in the asymptomatic group. In non-chagasic CHF patients, ANF levels were higher than in CD patients and controls in both samples. ANF levels were not able to differentiate chagasic asymptomatic and CD patients from healthy subjects and CD controls; meanwhile, chagasic CHF patients showed lower plasma ANF than their controls. Furthermore, ANF is a sensitive marker capable of detecting gradual impairments in cardiac function in all patients studied.     

Relationship between the TLR2 and TLR4 gene polymorphisms with a predisposition to certain urogenital infections

The distribution of the TLR2 Arg753Gln, TLR4 Asp299Gly and TLR4 Thr399Ile polymorphisms among residents of Poltavsky region was studied. The relationship between these polymorphisms and the presence of diseases caused by urogenital infections was also studied. The population control group was a random sample of residents of Poltavsky region (n = 299); the group of patients with urogenital diseases consisted of 156 individuals. PCR and subsequent restriction analysis were used to enable the genotyping of the following TLR polymorphisms in these groups: Arg753Gln, Asp299Gly, and TLR4 Thr399Ile. We found a statistically significant correlation between the presence of allele A of the TLR2 gene (p = 0.0018) and allele G of the TLR4 gene (p = 0.085) and the presence of urogenital diseases.     

TLR4 and TLR9 polymorphism: Probable role in susceptibility among the population of Bihar for Indian visceral leishmaniasis

Genetic variations in the host TLRs genes play an important role in susceptibility and/or resistance to visceral leishmaniasis by altering the host-pathogen interaction. In this study, we investigated the association between polymorphisms of TLR4 (Asp299Gly, Thr399Ile) and TLR-9 (T-1237C), with susceptibility to visceral leishmaniasis. A bi-directional PCR amplification of specific alleles technique was used to characterize the distribution of TLR4 (Asp299Gly and Thr399Ile) and TLR9 (T-1237C) polymorphisms. A total of 60 samples were randomly selected from confirmed visceral leishmaniasis patients and 24 endemic healthy volunteers. The samples were genotyped and allele frequencies were determined. We observed that TLR4 Asp299Gly and Thr399Ile genotypes were more frequent in visceral leishmaniasis patients (10% and 15% respectively) compared to controls (4.2% and 8.3% respectively). However, the differences were not significant in TLR4 Asp299Gly and Thr399Ile alleles and genotypes. In the case of TLR9, we observed the frequency of T1237C genotype was higher in visceral leishmaniasis patients (43.3%) than in healthy controls (33.3%). Statistically significant differences were observed in TLR9 T1237C alleles and genotypes. We concluded that TLR9 T1237C, but not TLR4, gene polymorphisms can be regarded as contributors to visceral leishmaniasis susceptibility among the Indian population of Bihar state.     

Toll-like receptor polymorphisms and vasculitis susceptibility: meta-analysis and systematic review

The aim of this study was to determine whether toll-like receptor (TLR) polymorphisms confers susceptibility to vasculitis. A literature search was conducted using the PubMed and Embase. A meta-analysis on the associations between the TLR4 Asp299Gly polymorphisms and vasculitis was carried out using allele contrast, dominant, and codominant models and a systematic review of other TLR polymorphisms. Fourteen studies involving 2,064 patients and 2,481 controls were included in this systematic review, which comprised nine on Behcet’s disease (BD), three on giant cell arteritis (GCA), and one on Henoch–Schenlein purpura (HSP). Meta-analysis of six studies showed a significant association between the Gly/Gly+Gly/Asp genotype of the TLR4 Asp299Gly polymorphism and vasculitis and GCA (Odds ratio [OR] = 1.368, 95 % confidence interval [CI] = 1.300–1.815, p = 0.030; OR = 1.523, 95 % CI = 1.099–2.112, p = 0.012). Under a random effects model, the adjusted ORs calculated using the trim and fill technique revealed an association between the Gly/Gly+Gly/Asp genotype of the TLR4 Asp299Gly polymorphism and vasculitis (OR = 1.544, 95 % CI = 1.091–2.185, p < 0.05). Stratification by vasculitis type using the codominant model showed the trend for the association with GCA (OR = 1.569, 95 % CI = 0.970–2.538, p = 0.066). There were three studies on the TLR2 Arg753Gln polymorphism and two on the TLR4 Thr399Ile polymorphism; no association with vasculitis was evident. Among the TLR2, TLR7, and TLR9 polymorphisms included in this review, one Asian study revealed a significant association between the TLR7 rs5743733 and rs3853839 with BD (p = 0.002, 0.036) and one Asian study showed an association of TLR9 rs352140 with BD (p = 0.009). This meta-analysis demonstrates that the TLR4 Asp299Gly polymorphism may confer susceptibility to GCA. The review of published data suggests that other TLR polymorphisms such as TLR7 and TLR9 may play a role in vasculitis.     

Cardioprotective effects of phosphoramidon on myocardial structure and function in murine Chagas' disease

Chagas' disease is an important cause of cardiomyopathy. Endothelin-1, a vasoactive peptide has been implicated in the pathogenesis of chagasic cardiomyopathy. C57BL/6 x 129sv and CD1 mice were thus, infected with trypomastigotes of Trypanosoma cruzi (Brazil strain) and these infected mice were compared with infected mice treated with phosphoramidon. This compound inhibits endothelin-converting enzyme and neutral endopeptidases and does not affect the growth of the parasite in culture. Phosphoramidon was given in a dose of 10mg/kg for the initial 15 days post-infection None of the C57Bl/6 x 129sv mice died as a result of infection. However, there was marked myocardial inflammation and fibrosis in infected, untreated mice. The hearts of the infected, phosphoramidon-treated mice showed significantly less pathology. Cardiac magnetic resonance imaging of infected mice revealed right ventricular dilation that was less severe in those treated with phosphoramidon. Phosphoramidon-treated CD1 mice survived the acute infection. Transthoracic echocardiography demonstrated left ventricular dilation and reduced percent fractional shortening and relative wall thickness. These alterations were also attenuated as a result of phosphoramidon treatment. These data suggest that endothelin-1 contributes to the pathogenesis of chagasic cardiomyopathy and interventions that inhibit the synthesis of endothelin-1 and/or neutral endopeptidase might have a protective effect on myocardial structure and function in murine Chagas' disease.     

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

Background:  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.
Materials and Methods:  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.
Results:  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.
Conclusion:  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.     

R753Q Polymorphism Inhibits Toll-like Receptor (TLR) 2 Tyrosine Phosphorylation,Dimerization with TLR6, and Recruitment of Myeloid Differentiation Primary Response Protein 88

The R753Q polymorphism in the Toll-IL-1 receptor domain of Toll-like receptor 2 (TLR2) has been linked to increased incidence of tuberculosis and other infectious diseases, but the mechanisms by which it affects TLR2 functions are unclear. Here, we studied the impact of the R753Q polymorphism on TLR2 expression, hetero-dimerization with TLR6, tyrosine phosphorylation, and recruitment of myeloid differentiation primary response protein (MyD) 88 and MyD88 adapter-like (Mal). Complementation of HEK293 cells with transfected WT or R753Q TLR2 revealed their comparable total levels and only minimal changes in cell surface expression of the mutant species. Notably, even a 100-fold increase in amounts of transfected R753Q TLR2 versus WT variant did not overcome the compromised ability of the mutant TLR2 to activate nuclear factor κB (NF-κB), indicating that a minimal decrease in cell surface levels of the R753Q TLR2 cannot account for the signaling deficiency. Molecular modeling studies suggested that the R753Q mutation changes the electrostatic potential of the DD loop and results in a discrete movement of the residues critical for protein-protein interactions. Confirming these predictions, biochemical assays demonstrated that R753Q TLR2 exhibits deficient agonist-induced tyrosine phosphorylation, hetero-dimerization with TLR6, and recruitment of Mal and MyD88. These proximal signaling deficiencies correlated with impaired capacities of the R753Q TLR2 to mediate p38 phosphorylation, NF-κB activation, and induction of IL-8 mRNA in transfected HEK293 cells challenged with inactivated Mycobacterium tuberculosis or mycobacterial components. Thus, the R753Q polymorphism renders TLR2 signaling-incompetent by impairing its tyrosine phosphorylation, dimerization with TLR6, and recruitment of Mal and MyD88.     

Toll-like receptor 4 polymorphism impairing lipopolysaccharide signaling in Sus scrofa, and its restricted distribution among Japanese wild boar populations

Toll-like receptor 4 (TLR4) responds to lipid A, the active moiety of lipopolysaccharide from gram-negative bacteria, in cooperation with myeloid differentiation protein-2 and plays a vital role in innate immunity. Polymorphisms in TLR4 are associated with changes in susceptibility to various infectious diseases. We previously found seven amino acid polymorphisms in Sus scrofa TLR4. In this study, we showed by luciferase reporter assay that an alteration from cysteine to tryptophan at position 506 (C506W) caused loss of ability to induce nuclear factor-κB activation after lipid A stimulation. This polymorphism was found only in Japanese wild boar (JWB) populations of S. scrofa. Genotyping of TLR4 in different JWB populations revealed that C506W polymorphism was under pressure from purifying selection in a local population (Tajima's D=-0.98; p<0.05). However, in another population, this polymorphism existed at a frequency such that homozygous animals with the W506 alleles seldom appeared. These findings suggest that the C506W polymorphism is under different types of pressure by natural selection between populations, which may reflect differences in residential pathogens or demographic factors.     

Cell mediated immunity in Chagas' disease. Trypanosoma cruzi antigens induce suppression of the in vitro proliferative response of mononuclear cells.

The partial suppression of the cell-mediated immune response by Trypanosoma cruzi antigens in patients with Chagas' disease is demonstrated in a costimulation assay with T. cruzi antigens and Mycobacterium tuberculosis purified protein derivative (PPD) or Tetanus toxoid (TT). Mononuclear cells from 13 patients with chagasic infection without evidence of heart disease, 10 patients with chagasic cardiomyopathy and 7 healthy blood bank donors were stimulated with antigen A (autoclaved epimastigotes), PPD, TT, PPD + A, PPD + TT and TT + A. The average percentage of suppression induced by costimulation of mononuclear cells with PPD and antigen A was 47.1% in patients with chagasic infection without heart disease (INF), 38.8% in patients with chagasic cardiomyopathy (CDM) and 23.3% in healthy controls. Similar values were observed when living trypomastigotes were used. A costimulatory study with PPD and TT, PPD and A and TT and A was carried out in 8 patients with chagasic infection, in order to evaluate the possibility that this difference could be due to a nonspecific inhibitory effect. The mean suppression induced by TT + PPD was -8.9, with TT + A was 52.7 and with PPD + A was 50.1. The data reported show that T. cruzi antigens induce a specific suppression of the proliferative response of mononuclear cells, that might be relevant to the persistence of the parasite in the host.     

Immunoenzyme assay using micro Dot on nitrocellulose (Dot-ELISA) in the diagnosis of Chagas' disease. I. Comparative study of 2 antigenic preparations of Trypanosoma cruzi

Using the Dot-ELISA technique, two antigenic preparations of Trypanosoma cruzi epimastigote forms have been compared for the diagnosis of Chagas' disease: (1) The cytoplasmic fraction (cytoplasmic antigen) and (2) whole formalin fixed epimastigotes (integral antigen). There was been used sera from 95 chagasic patients with chronic cardiomyopathy, positive conventional serology and either positive or negative xenodiagnosis; 74 subjects with negative conventional serology, and either clinically normal or presenting cardiomyopathy; 74 patients with different diseases including syphilis, toxoplasmosis, leishmaniasis or autoantibodies such as rheumatoid factor and antinuclear antibodies. By defining the diagnostic titers (cut off): 1:512 for cytoplasmic antigen and 1:128 for the integral antigen, a sensitivity of 100% has been obtained with both antigenic preparations, being the specificity of 96% for the former and 100% for the latter when leishmaniasis sera were not included. A comparative study with conventional serology was carried out using 147 sera from a Laboratory of Chagas' diagnosis; Dot-ELISA with cytoplasmic antigen showed co-positivity index of 1.0, co-negativity 0.989 and efficiency of 0.993, and Dot-ELISA with integral antigen 1.0, 0.979 and 0.986 respectively. According to this evaluation, Dot-ELISA using whole formalin fixed epimastigotes might be a practical alternative for the serological diagnosis of Chagas' disease.     

Nasopharyngeal bacterial colonization and gene polymorphisms of mannose-binding lectin and toll-like receptors 2 and 4 in infants

Background

Human nasopharynx is often colonized by potentially pathogenic bacteria. Gene polymorphisms in mannose-binding lectin (MBL), toll-like receptor (TLR) 2 and TLR4 have been reported. The present study aimed to investigate possible association between nasopharyngeal bacterial colonization and gene polymorphisms of MBL, TLR2 and TLR4 in healthy infants.

Methodology/Principal Findings

From August 2008 to June 2010, 489 nasopharyngeal swabs and 412 blood samples were taken from 3-month-old healthy Finnish infants. Semi-quantitative culture was performed and pyrosequencing was used for detection of polymorphisms in MBL structural gene at codons 52, 54, and 57, TLR2 Arg753Gln and TLR4 Asp299Gly. Fifty-nine percent of subjects were culture positive for at least one of the four species: 11% for Streptococcus pneumoniae, 23% for Moraxella catarrhalis, 1% for Haemophilus influenzae and 25% for Staphylococcus aureus. Thirty-two percent of subjects had variant types in MBL, 5% had polymorphism of TLR2, and 18% had polymorphism of TLR4. Colonization rates of S. pneumoniae and S. aureus were significantly higher in infants with variant types of MBL than those with wild type (p = .011 and p = .024). Colonization rates of S. aureus and M. catarrhalis were significantly higher in infants with polymorphisms of TLR2 and of TLR4 than those without (p = .027 and p = .002).

Conclusions

Our study suggests that there is an association between nasopharyngeal bacterial colonization and genetic variation of MBL, TLR2 and TLR4 in young infants. This finding supports a role for these genetic variations in susceptibility of children to respiratory infections.