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

Cytokine Networks as Targets for Preventing and Controlling Chagas Heart Disease

Chagas disease, a neglected disease caused by the protozoan Trypanosoma cruzi, is endemic in 21 Latin American countries, affecting 6-8 million people. Increasing numbers of Chagas disease cases have also been reported in non-endemic countries due to migration, contamination via blood transfusions or organ transplantation, characterizing Chagas as an emerging disease in such regions. While most individuals in the chronic phase of Chagas disease remain in an asymptomatic clinical form named indeterminate, approximately 30% of the patients develop a cardiomyopathy that is amongst the deadliest cardiopathies known. The clinical distinctions between the indeterminate and the cardiac clinical forms are associated with different immune responses mediated by innate and adaptive cells. In this review, we present a collection of studies focusing on the human disease, discussing several aspects that demonstrate the association between chemokines, cytokines, and cytotoxic molecules with the distinct clinical outcomes of human infection with Trypanosoma cruzi. In addition, we discuss the role of gene polymorphisms in the transcriptional control of these immunoregulatory molecules. Finally, we discuss the potential application of cytokine expression and gene polymorphisms as markers of susceptibility to developing the severe form of Chagas disease, and as targets for disease control.

IgG Subclass Analysis in Patients with Chagas Disease 4 Years After Benznidazole Treatment

BACKGROUND

In humans, Trypanosoma cruzi infection is controlled by a complex immune response. Immunoglobulin G (IgG) is important for opsonizing blood trypomastigotes, activating the classic complement pathway, and reducing parasitemia. The trypanocidal activity of benznidazole is recognized, but its effects on the prevention and progression of Chagas disease is not well understood OBJECTIVE: We aimed to evaluate the levels of total IgG and cross-specific IgG subclasses in patients with chronic Chagas disease of different clinical forms before and after 4 years of benznidazole treatment.

METHODS

Eight individuals with the indeterminate form and nine with the cardiac form who completed the treatment protocol were evaluated. The levels of total IgG and IgG1, IgG2, IgG3, and IgG4 isotypes were quantified in the serum of each individual using the fluorescent immunosorbent assay. The results are expressed as relative fluorescence unit.

RESULTS

Patients with chronic Chagas disease presented decreased levels of total IgG at 48 months after benznidazole treatment. Increased IgG1 and decreased IgG3 levels were observed in patients with the cardiac form and those with exacerbated clinical forms. In addition, a decrease in the IgG3/IgG1 ratio was observed in individuals with the cardiac form of Chagas disease.

CONCLUSIONS

Benznidazole administration in the chronic phase differentially changes IgG subclasses in patients with cardiac and indeterminate forms, and monitoring the IgG3 level may indicate the possible prognosis to the cardiac form or worsening of the already established clinical form.

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.

Genomic medicine in Chagas disease

Genetic approaches have been proposed for improving the understanding of the causes of differential susceptibility to Trypanosoma cruzi infection and Chagas disease outcome. Polymorphisms in genes involved in the immune/inflammatory response are being studied in order to clarify their possible role in the occurrence or severity of the cardiac and/or gastrointestinal complications. However still today, the number of significant associated genes is limited and the pathophysiological mechanisms underlying this condition are unknown. This article review the information currently available from the published scientific literature regarding the genetic variants of molecules of the immune system and other variants that can contribute to the clinical presentation of the disease. Genomic medicine will improve our knowledge about the molecular basis of Chagas disease, will open new avenues for developing biomarkers of disease progression, new therapeutic strategies to suit the requirements of individual patients, and will contribute to the control of one of the infections with the greatest socio-economic impact in the Americas.

A clinical association between Toll-like receptor 2 Arg753Gln polymorphism with recurrent cystic echinococcosis in postsurgery patients: A case control study

Recurrence of hydatid cysts in cystectomy patients has dramatically remained a serious concern within the surgical community. Predisposing factors for recurrence of hydatid cysts remained to be identified. Toll-like receptor (TLR) plays a pivotal role in bridging between acquired and innate immunity in cystic echinococcosis (CE) infection. 117 CE patients including 66 acute hydatidosis (AH; primary infection) and 51 recurrent hydatidosis (RH; chronic infection), and 117 ethnically matched healthy control (HC) were investigated from endemic regions of Iran in the period of 2015-2018. CE patients were definitely confirmed using histopathological and immunological assays. Genotyping of TLR2 Arg753Gln was carried out by restriction fragment length polymorphism and sequencing. The homozygous mutant-type TLR2 Gln/Gln (A/A) was represented to be associated with the occurrence of RH (P = 0.04) and conferred a 9 fold risk for susceptibility, while the heterozygous mutant-type TLR2 Arg/Gln (G/A) indicated a tendency to be associated with the occurrence of RH (P = 0.07). There was no discrepancy in the frequency of TLR2 Arg753Gln haplotypes between AH patients and HC individuals (P = 0.09). The mutant allele A was observed to be a risk factor for susceptibility to RH patients. Our results point to a clinical association between TLR2 Arg753Gln haplotypes with RH in postoperative patients. It can be inferred that allele G may lead to protection against the CE, while mutant allele A may be a diagnostic hallmark in the screening of RH susceptibility. Nevertheless, further studies with a larger sample size of different ethnic populations are required to authenticate this association.

Susceptibility to HIV-1 infection is influenced by toll like receptor-2 (-196 to -174) polymorphism in a north Indian population

BACKGROUND

Toll like receptors (TLRs) are pattern recognition receptors that recognize molecular patterns of pathogens and play an important role in innate immunity. Recent studies have identified that a single nucleotide polymorphism (SNP) in the TLR gene impairs the response to TLR ligands in some individuals and is associated with susceptibility to various infectious diseases. The present study aimed to investigate the role of four SNPs in the TLR2 gene [-196 to -174 Ins/Del, 2258 G/A (Arg753Gln), 2029 C/T (Arg677Trp) and 1892 C/A (Pro631His)] with respect to susceptibility and progression to HIV-1 in North Indian individuals.

METHODS

The study population consisted of 160 HIV-1 seropositive patients stratified on the basis of disease severity (stages I, II and III) and 270 HIV-1 seronegative individuals. The subjects were genotyped for TLR2 gene polymorphism by polymerase chain reaction restriction fragment length polymorphism.

RESULTS

In the present study, we found that the TLR2 Del mutant genotype [odds ratio (OR) = 2.138; p = 0.001] and allele (OR = 1.562; p = 0.002) was at a higher frequency in patients with HIV-1 infection compared to healthy controls and was significantly associated with the risk of HIV-1 infection and disease susceptibility. Furthermore, we also found that TLR2 Del homozygous genotype was at a lower frequency in stage III (19.35%) compared to stage I (50.87%; OR = 1.901) and stage II (43.05%; OR = 1.514) and was associated with a reduced risk of HIV-1 disease progression.

CONCLUSIONS

The present study reports for the first time that the TLR2-196 to -174 Ins/Del polymorphism is a risk factor for HIV-1 transmission in HIV-1 infected North Indian individuals.

The potential role of toll-like receptor 4 Asp299Gly polymorphism and its association with recurrent cystic echinococcosis in postoperative patients

The study of pathogenesis mechanisms of larval stages in the Taeniidae has recently focused on host genetic factors, particularly toll-like receptor (TLR) variations. However, the potential role of TLR4 polymorphism in hydatidosis has not yet been sufficiently elucidated in postoperative patients. In this case-control investigation, 80 patients from Iran, including 40 with acute hydatidosis (AH) and 40 with recurrent hydatidosis (RH), and 80 ethnically matched controls were evaluated from February 2015 to February 2017. Hydatidosis patients were confirmed using radiological, immunological, and histopathological examinations. Genotyping of Asp299Gly and Thr399Ile of TLR4 single-nucleotide polymorphisms was determined by restriction fragment length polymorphism, sequencing, and phylogenetic strategies. The heterozygous mutant-type TLR4 Asp299Gly genotype indicated a tendency to be associated with the occurrence of RH (P = 0.060) and conferred a 3-fold risk for susceptibility. There was no difference in genotype frequency of Asp299Gly between patients with AH and healthy controls (P = 0.42; OR, 1.82; 95% CI, 0.11-30.1%). Interestingly, a frequency of the G allele (12%: Gly) was observed to be a risk factor for susceptibility to RH patients (P = 0.050; OR, 7.08; 95% CI, 0.97-51.5%). A relative genetic variability of TLR4 Asp299Gly was found in RH patients (haplotype diversity: 0.700) compared to AH patients and healthy controls (Hd: 0.000). The Asp299Gly genotype was dominantly identified in patients with hepatic hydatid cysts. The TLR4 Thr399Ile codon was not detected except in a patient with a pulmonary hydatid cyst. The current findings enhance our knowledge regarding the TLR4 Asp299Gly polymorphism potentially leading to the development of RH, by skewing the immune system towards a Th2 response. Identification of the Asp299Gly codon may be a diagnostic hallmark in RH patients who have undergone unsuccessful postoperative intervention. However, further studies with a higher case number are needed on ethnic population from various geographic regions, in order to confirm this hypothesis.

Association of TLR variants with susceptibility to Plasmodium vivax malaria and parasitemia in the Amazon region of Brazil

BACKGROUND

Plasmodium vivax malaria (Pv-malaria) is still considered a neglected disease despite an alarming number of individuals being infected annually. Malaria pathogenesis occurs with the onset of the vector-parasite-host interaction through the binding of pathogen-associated molecular patterns (PAMPs) and receptors of innate immunity, such as toll-like receptors (TLRs). The triggering of the signaling cascade produces an elevated inflammatory response. Genetic polymorphisms in TLRs are involved in susceptibility or resistance to infection, and the identification of genes involved with Pv-malaria response is important to elucidate the pathogenesis of the disease and may contribute to the formulation of control and elimination tools.

METHODOLOGY/PRINCIPAL FINDINGS

A retrospective case-control study was conducted in an intense transmission area of Pv-malaria in the state of Amazonas, Brazil. Genetic polymorphisms (SNPs) in different TLRs, TIRAP, and CD14 were genotyped by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis in 325 patients infected with P. vivax and 274 healthy individuals without malaria history in the prior 12 months from the same endemic area. Parasite load was determined by qPCR. Simple and multiple logistic/linear regressions were performed to investigate association between the polymorphisms and the occurrence of Pv-malaria and parasitemia. The C/T (TLR5 R392StopCodon) and T/T (TLR9 -1486C/T) genotypes appear to be risk factors for infection by P. vivax (TLR5: C/C vs. C/T [OR: 2.116, 95% CI: 1.054-4.452, p = 0.031]; TLR9: C/C vs. T/T [OR: 1.919, 95% CI: 1.159-3.177, p = 0.010]; respectively). Fever (COEF = 7599.46, 95% CI = 3063.80-12135.12, p = 0.001) and the C/C genotype of TLR9 -1237C/T (COEF = 17006.63, 95% CI = 3472.83-30540.44, p = 0.014) were independently associated with increased parasitemia in patients with Pv-malaria.

CONCLUSIONS

Variants of TLRs may predispose individuals to infection by P. vivax. The TLR5 R392StopCodon and TLR9 -1486C/T variants are associated with susceptibility to Pv-malaria. Furthermore, the TLR9 variant -1237C/C correlates with high parasitemia.

Screening of TNFα, IL-10 and TLR4 single nucleotide polymorphisms in individuals with asymptomatic and chronic cutaneous leishmaniasis in Colombia: a pilot study

BACKGROUND

Clinical manifestations of cutaneous leishmaniasis (CL) caused by Leishmania (Viannia) range from asymptomatic infection to self-limited, or chronic (non-healing) cutaneous lesions. Given the critical role of the immune response in the clinical outcome of CL, it is plausible that functional polymorphisms in immune-related genes contribute to define the clinical manifestations of human infection.

METHODS

DNA samples from a retrospective cohort of individuals from an endemic area of L. V. panamensis transmission in Colombia were used to determine the frequency of SNPs in TNFα, IL-10 and TLR4 genes. DNA samples were obtained from 74 adult participants: 38 patients presenting chronic cutaneous leishmaniasis (CCL) and 36 individuals with asymptomatic infection. Genotyping of TNFα-308G/A, IL-10-819C/T, and TLR4 Asp299Gly and Thr399Ile SNPs, was conducted by PCR-restriction fragment length polymorphisms. Allele, genotype frequencies and associations between SNPs and clinical groups were evaluated.

RESULTS

The A allele in TNFα-308G/A SNP was found more frequently in individuals with asymptomatic infection (16% vs 7%), whereas the CC genotype in IL-10-819 C/T SNP was more frequent in patients with CCL (34% vs. 27% in asymptomatic individuals). No differences in allele frequencies for TLR4 SNPs were found among groups.

CONCLUSION

This study provides a reference base for statistical power calculation and design of association studies of genetic polymorphisms in immune response related-genes and the pathogenesis of infections caused by L. V. panamensis.

Investigation of the role of IL17A gene variants in Chagas disease

Human host genetic factors have been suggested to be determinants of the prevalence and clinical forms of Chagas disease. In this regard, IL-17A is believed to control parasitemia and protect against heart disease. In this work, we assessed whether IL17A gene polymorphisms are related to infection and/or development of the cardiac form of Chagas disease by genotyping for five IL17A SNPs (rs4711998, rs8193036, rs3819024, rs2275913 and rs7747909) in 1171 individuals from a Colombian region endemic for Chagas disease, classified as seronegative (n=595), seropositive asymptomatic (n=175) and chronic Chagas cardiomyopathy (n=401). Our results showed that SNP rs8193036, which is located upstream of the coding region of the gene, was slightly associated with protection against T. cruzi infection (P=0.0170, P(FDR)=0.0851, odds ratio (OR)=0.80, confidence interval (CI)=0.66-0.96) and associated with protection against the development of cardiomyopathy (P=0.0065, P(FDR)=0.0324, OR=0.75, CI=0.60-0.92). This finding suggests that this IL17A polymorphism could be associated with Trypanosoma cruzi infection and the development of chronic cardiomyopathy due to differential expression of cytokine IL-17A.

Chagas disease cardiomyopathy: immunopathology and genetics

Chagas disease, caused by the protozoan Trypanosoma cruzi, is endemic in Latin America and affects ca. 10 million people worldwide. About 30% of Chagas disease patients develop chronic Chagas disease cardiomyopathy (CCC), a particularly lethal inflammatory cardiomyopathy that occurs decades after the initial infection, while most patients remain asymptomatic. Mortality rate is higher than that of noninflammatory cardiomyopathy. CCC heart lesions present a Th1 T-cell-rich myocarditis, with cardiomyocyte hypertrophy and prominent fibrosis. Data suggest that the myocarditis plays a major pathogenetic role in disease progression. Major unmet goals include the thorough understanding of disease pathogenesis and therapeutic targets and identification of prognostic genetic factors. Chagas disease thus remains a neglected disease, with no vaccines or antiparasitic drugs proven efficient in chronically infected adults, when most patients are diagnosed. Both familial aggregation of CCC cases and the fact that only 30% of infected patients develop CCC suggest there might be a genetic component to disease susceptibility. Moreover, previous case-control studies have identified some genes associated to human susceptibility to CCC. In this paper, we will review the immunopathogenesis and genetics of Chagas disease, highlighting studies that shed light on the differential progression of Chagas disease patients to CCC.

The role of TLR4 896 A>G and 1196 C>T in susceptibility to infections: a review and meta-analysis of genetic association studies

Background

Toll-like receptor 4 plays a role in pathogen recognition, and common polymorphisms may alter host susceptibility to infectious diseases.

Purpose

To review the association of two common polymorphisms (TLR4 896A>G and TLR4 1196C>T) with infectious diseases.

Data Sources

We searched PubMed and EMBASE up to March 2013 for pertinent literature in English, and complemented search with references lists of eligible studies.

Study Selection

We included all studies that: reported an infectious outcome; had a case-control design and reported the TLR4 896A>G and/or TLR4 1196C>T genotype frequencies; 59 studies fulfilled these criteria and were analyzed.

Data Extraction

Two authors independently extracted study data.

Data Synthesis

The generalized odds ratio metric (OR_G) was used to quantify the impact of TLR4 variants on disease susceptibility. A meta-analysis was undertaken for outcomes reported in >1 study. Eleven of 37 distinct outcomes were significant. TLR4 896 A>G increased risk for all parasitic infections (OR_G 1.59; 95%CI 1.05-2.42), malaria (1.31; 95%CI 1.04-1.66), brucellosis (2.66; 95%CI 1.66-4.27), cutaneous leishmaniasis (7.22; 95%CI 1.91-27.29), neurocysticercosis (4.39; 95%CI 2.53-7.61), Streptococcus pyogenes tonsillar disease (2.93; 95%CI 1.24-6.93) , typhoid fever (2.51; 95%CI 1.18-5.34) and adult urinary tract infections (1.98; 95%CI 1.04-3.98), but was protective for leprosy (0.36; 95%CI 0.22-0.60). TLR4 1196 C>T effects were similar to TLR4 896 A>G for brucellosis, cutaneous leishmaniasis, leprosy, typhoid fever and S. pyogenes tonsillar disease, and was protective for bacterial vaginosis in pregnancy (0.55; 95%CI 0.31-0.98) and Haemophilus influenzae tonsillar disease (0.42; 95%CI 0.17-1.00). The majority of significant associations were among predominantly Asian populations and significant associations were rare among European populations.

Conclusions

Depending on the type of infection and population, TLR4 polymorphisms are associated with increased, decreased or no difference in infectious disease. This may be due to differential functional expression of TLR4, the co-segregation of TLR4 variants or a favorable inflammatory response.

Association between TLR4 and TLR9 gene polymorphisms with development of pulmonary tuberculosis in Zahedan, southeastern Iran

Some evidence suggests that a variety of genetic factors contribute to development of the tuberculosis (TB). TLR4 and TLR9 have been proposed as susceptibility genes for TB. This study was performed in 124 newly diagnosed TB cases and 149 healthy controls in a TB-endemic region of Iran. The TLR4 genes Asp299Gly, Thr399Ile, and TLR9 gene T-1486C polymorphisms were amplified by polymerase chain reaction (PCR) and then detected by PCR-restriction fragment length polymorphism (RFLP). The frequencies of the mutant alleles of TLR4 Arg299Gly, Thr399Ile, and TLR9 T-1486C polymorphisms were 0.8 versus 0.1, 5.6 versus 3, and 28.6 versus 25.2 in patients and controls, respectively, that were not significant. The synergic effect of TI,II/CC genotypes for TLR4 Thr399Ile and TLR9 T-1486C polymorphisms showed increased risk of PTB susceptibility. In conclusion, no significant relation was found between TLR4 and TLR9 polymorphisms alone and PTB. However, synergic effects of TLR4 Thr399Ile and TLR9-1486T/C polymorphisms might increase risk of PTB.

Pathogenesis of Chagas disease cardiomyopathy

Chagas disease, or American trypanosomiasis, is a parasitic infection caused by the flagellate protozoan Trypanosoma cruzi. Chagas disease is mainly affecting rural populations in Mexico and Central and South America. The World Health Organization estimates that 300 000 new cases of Chagas disease occur every year and approximately 20 000 deaths are attributable to Chagas. However, this organisation classified Chagas disease as a neglected tropical disease. The economic burden of this disease is significant. In many Latin American countries, the direct and indirect costs, including the cost of health care in dollars and loss of productivity, attributable to Chagas disease ranges from $40 million to in excess of $800 million per nation per annum. So, it remains a contemporary public health concern. In chronic phase, mortality is primarily due to the rhythm disturbances and congestive heart failure that result from the chronic inflammatory cardiomyopathy (CCC) due to the persistence presence of parasites in the heart tissue. Mechanisms underlying differential progression to CCC are still incompletely understood. In the last decades immunological proteomic genetic approaches lead to significant results which help to disperse the veil covering the knowledge of the pathogenic process. Here, we reported these significant progresses.

Mannose-binding lectin and Toll-like receptor polymorphisms and Chagas disease in Chile

Mannose-binding lectin (MBL) and Toll-like receptor (TLR) polymorphisms may influence susceptibility and manifestation of Trypanosoma cruzi infection. In northern Chile, we examined 61 asymptomatic patients with chronic Chagas disease (CD), 64 patients with chronic Chagas cardiomyopathy (CCC), and 45 healthy individuals. Low-producer MBL2*B genotypes were more common in CD patients (48%) than healthy individuals (31%; adjusted odds ratio = 2.3, 95% confidence interval = 1.01-5.4, P = 0.047) but did not differ with manifestation. In contrast, the heterozygous Toll-like receptor 4 (TLR4)-deficiency genotype D299G/T399I occurred more frequently in asymptomatic (14.8%) than CCC patients (3.1%; P = 0.02). TLR1-I602S, TLR2-R753Q, TLR6-S249P, and MAL/TIRAP-S180L did not associate with CD or CCC. These findings support the complement system to be involved in defense against Trypanosoma cruzi infection and indicate that curbed TLR4 activation might be beneficial in preventing CCC.

Different patterns of Toll-like receptor 2 polymorphisms in populations of various ethnic and geographic origins

Upon the invasion of the host by microorganisms, innate immunity is triggered through pathogen recognition by pattern recognition receptors (PRRs). Toll-like receptors (TLRs) are the best-studied class of PRRs, and they recognize specific pathogen-associated molecular patterns (PAMPs) from various microorganisms. A large number of studies have shown that genetic variation in TLRs may influence susceptibility to infections. We assessed the genetic variation of TLR2, which encodes one of the most important TLRs, in various populations around the globe and correlated it with changes in the function of the molecule. The three best-known nonsynonymous TLR2 polymorphisms (1892C>A, 2029C>T, and 2258G>A) were assessed in different populations from the main continental masses: Romanians, Vlax-Roma, Dutch (European populations), Han Chinese (East Asia), Dogon, Fulani (Africa), and Trio Indians (America). The 2029C>T polymorphism was absent in both European and non-European populations, with the exception of the Vlax-Roma, suggesting that this polymorphism most likely arose in Indo-Aryan people after migration into South Asia. The 1892C>A polymorphism that was found exclusively in European populations, but not in Asian, African, or American volunteers, probably occurred in proto-Indo-Europeans. Interestingly, 2258G>A was present only in Europeans, including Vlax-Roma, but at a very low frequency. The differential pattern of the TLR2 polymorphisms in various populations may explain some of the differences in susceptibility to infections between these populations.

Very low frequencies of Toll-like receptor 2 supposed-2029T and 2258A (RS5743708) mutant alleles in southern Brazilian critically ill patients: would it be a lack of worldwide-accepted clinical applications of Toll-like receptor 2 variants?

Toll-like receptor 2 (TLR2) is a recognition receptor for the widest repertoire of pathogen-associated molecular patterns. Two polymorphisms of TLR2 could be linked to reduced nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kB) activation and to increased risk of infection (supposed-2029C>T and 2258G>A). We investigated the supposed-2029C>T and 2258G>A TLR2 polymorphisms in 422 critically ill patients of European origin from southern Brazil (295 with sepsis and 127 without sepsis) and reviewed 33 studies on these polymorphisms, conducting a quality assessment with a score system. Among our patients we found only one heterozygote (1/422) for the supposed-2029C>T and none for the 2258G>A (0/422) single nucleotide polymorphism (SNP). We were unable to find a clinical application of supposed-2029T and 2258A allele analyses in our southern Brazilian population. Our review detected that current TLR2 SNP assays had very controversial and contradictory results derived from reports with a variety of investigation quality criteria. We suggest that, if analyzed alone, the supposed-2029C>T and 2258G>A TLR2 SNP are not good candidates for genetic markers in studies that search for direct or indirect clinical applications between genotype and phenotype. Future efforts to improve the knowledge and to provide other simultaneous genetic markers might reveal a more effective TLR2 effect on the susceptibility to infectious diseases.

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.