TLR4 single-nucleotide polymorphisms alter mucosal cytokine and chemokine patterns in Mexican patients with Helicobacter pylori-associated gastroduodenal diseases

Pathomorphological Manifestations and the Course of the Cervical Cancer Disease Determined by Variations in the TLR4 Gene

Cervical cancer (CC) is often associated with human papillomavirus (HPV). Chronic inflammation has been described as one of the triggers of cancer. The immune system fights diseases, including cancer. The genetic polymorphism of pathogen recognition receptors potentially influences the infectious process, development, and disease progression. Many candidate genes SNPs have been contradictory demonstrated to be associated with cervical cancer by association studies, GWAS. TLR4 gene activation can promote antitumor immunity. It can also result in immunosuppression and tumor growth. Our study aimed to investigate eight selected polymorphisms of the TLR4 gene (rs10759932, rs1927906, rs11536898, rs11536865, rs10983755, rs4986790, rs4986791, rs11536897) and to determine the impact of polymorphisms in genotypes and alleles on the pathomorphological characteristics and progression in a group of 172 cervical cancer subjects with stage I-IV. Genotyping was performed by RT-PCR assay. We detected that the CA genotype and A allele of rs11536898 were significantly more frequent in patients with metastases (p = 0.026; p = 0.008). The multivariate logistic regression analysis confirmed this link to be significant. The effect of rs10759932 and rs11536898 on progression-free survival (PFS) and overall survival (OS) has been identified as important. In univariate and multivariate Cox analyses, AA genotype of rs11536898 was a negative prognostic factor for PFS (p = 0.024; p = 0.057, respectively) and OS (p = 0.008; p = 0.042, respectively). Rs11536898 C allele predisposed for longer PFS (univariate and multivariate: p = 0.025; p = 0.048, respectively) and for better OS (univariate and multivariate: p = 0.010; p = 0.043). The worse prognostic factor of rs10759932 in a univariate and multivariate Cox analysis for survival was CC genotype: shorter PFS (p = 0.032) and increased risk of death (p = 0.048; p = 0.015, respectively). The T allele of rs10759932 increased longer PFS (univariate and multivariate: p = 0.048; p = 0.019, respectively) and longer OS (univariate and multivariate: p = 0.037; p = 0.009, respectively). Our study suggests that SNPs rs10759932 and rs11536898 may have the potential to be markers contributing to the assessment of the cervical cancer prognosis. Further studies, preferably with larger groups of different ethnic backgrounds, are needed to confirm the results of the current study.

Small-Molecule Modulators Targeting Toll-like Receptors for Potential Anticancer Therapeutics

Toll-like receptors (TLRs) are key components of the innate immune system and serve as a crucial link between innate and acquired immunity. In addition to immune function, TLRs are involved in other important pathological processes, including tumorigenesis. TLRs have dual regulatory effects on tumor immunity by activating nuclear factor κ-B signaling pathways, which induce tumor immune evasion or enhance the antitumor immune response. Therefore, TLRs have become a popular target for cancer prevention and treatment, and TLR agonists and antagonists offer considerable potential for drug development. The TLR7 agonist imiquimod (1) has been approved by the U.S. Food and Drug Administration as a treatment for malignant skin cancer. Herein, the structure, signaling pathways, and function of the TLR family are summarized, and the structure-activity relationships associated with TLR selective and multitarget modulators and their potential application in tumor therapy are systematically discussed.

Association of TLR4 gene 2026A/G (rs1927914), 896A/G (rs4986790), and 1196C/T (rs4986791) polymorphisms and cancer susceptibility: Meta-analysis and trial sequential analysis

BACKGROUND

This study was performed to assess the association of TLR4 gene 2026A/G (rs1927914), 896A/G (rs4986790), and 1196C/T (rs4986791) polymorphisms and cancer susceptibility based on published case-control studies.

METHODS

Web of Science, PubMed, Embase, CBM, WanFang Data, CNKI, and VIP database were used for article retrieving. Then, these articles were screened according to the study inclusion and exclusion criteria. The data was extracted, and the study quality was evaluated according to the principle of Newcastle-Ottawa Scale. Meta-analysis was performed by RevMan 5.4 and Stata MP-17 software. Trial sequential analysis was performed by TSA 0.9.5.10 Beta software.

RESULTS

Eighty-seven case-control studies including 25,969 cases and 32,119 controls were included in the meta-analysis. The diseases involved in case groups include prostate cancer, lung cancer, gastric cancer, hepatocellular carcinoma, colorectal cancer, etc. A versus G model of rs1927914, A versus G model of rs4986790 and C versus T model of rs4986791 showed that odds ratio (OR) = 1.08, OR = 0.85, and OR = 0.74 respectively. All the 3 comparisons were statistically significant. Sensitivity analysis showed that the results were stable. Publication bias analysis and trial sequential analysis showed that no significant publication bias was found in the results of the meta-analysis, and the probability of false positives was small.

CONCLUSION

People with A allele of rs1927914, G allele of rs4986790, or T allele of rs4986791 have higher risks of cancer. The results of meta-analysis are stable and have less probability of false positives.

An updated systematic review of the association between the TLR4 polymorphism rs4986790 and cancers risk

BACKGROUND

Toll-like receptor 4 (TLR4) is a lipopolysaccharide receptor that may influence tumor progression through inflammatory response and immune response. This complex process mainly occurs within cells. The correlation between TLR4 and neoplasms has been of great interest, but discrepancies remain.

METHODS

We analyze the literature retrieved from five databases (Web of Science, PubMed, Embase, CNKI, and Wan Fang) to assess the intensity of association using odds ratio (ORs) and 95% confidence intervals (95% CI). Meta-regression and subgroup analysis were utilized to find sources of heterogeneity. Publication bias is estimated using contour-enhanced funnel plots, Begg's test, and Egger's test, and we implemented sensitivity analysis to clarify the reliability of the outcomes. We also conducted an evaluation of the sample size using trial sequential analysis (TSA) method.

RESULTS

We found a significant association between rs4986790 and tumors (dominant model: OR [95% CI] = 1.25 [1.11-1.42]; heterozygous model OR [95% CI] = 1.25 [1.11-1.41]; and additive model: OR [95% CI] = 1.25 [1.10-1.41]. Specifically, the rs4986790 minor allele G may increase the risk of gastric cancer (dominant model: OR [95% CI] = 1.62 [1.3-2.03]; heterozygous model: OR [95% CI] = 1.57 [1.24-1.97]; additive model: OR [95% CI] = 1.64 [1.31-2.05] and other tumors (dominant model: OR [95% CI] = 1.36 [1.17-1.57]; heterozygous model: OR [95% CI] = 1.43 [1.25-1.63]; additive model: OR [95% CI] = 1.35 [1.18-1.55]. Further subgroup analysis showed that this association are both present in Caucasian and Asian.

CONCLUSION

The outcomes of our systemic review proved that the TLR4 polymorphism rs4986790 is associated with cancer, especially with gastric cancer, and this strong correlation are evident in Caucasians and Asian.

TAS2R38 polymorphisms, Helicobacter pylori infection and susceptibility to gastric cancer and premalignant gastric lesions

BACKGROUND

Gastric cancer is worldwide the fourth more common cancer type by incidence, and the third by mortality. We analyzed three missense variants of TAS2R38 gene: rs713598 (A49P), rs1726866 (V262A), and rs10246939 (I296V). These variants and their combination in haplotypes (proline, alanine and valine/tasters or alanine, valine and isoleucine/nontasters) and diplotypes are responsible for individual differences in bitter perception. The single-nucleotide polymorphisms and the related phenotypes are known to be associated with susceptibility to Gram-negative bacterial infections, such as Helicobacter pylori , and with risk of various cancer types. An association between intermediate tasters (as defined by TAS2R38 diplotypes) and increased risk of gastric cancer was reported in a Korean population.

METHODS

We analyzed 2616 individuals of Latin American origin, representing the whole spectrum of lesions from gastritis to gastric cancer.

RESULTS

Comparing cancer cases vs. noncancers we observed a decrease in risk associated with heterozygous carriers of rs10246939 ( P  = 0.006) and rs1726866 ( P  = 0.003) when compared with homozygotes of the more common allele. Also, the analysis of diplotypes/phenotypes reflected the same association, with super-tasters showing a borderline increased risk of developing gastric cancer compared to medium-tasters [odds ratio (OR) = 1.63; 95% confidence interval (CI), 1.04-2.56; P  = 0.033]. Also, nontasters showed an increased risk when compared to medium-tasters although not reaching statistical significance (OR = 1.58; 95% CI, 0.80-2.87; P  = 0.203). We also tested the interactions between the TAS2R38 genotypes and H. pylori cagA status in a subset of samples and found no interaction.

CONCLUSION

In conclusion, our results suggest only a modest contribution of TAS2R38 gene genetic variability in gastric cancer etiology.

Induction and Regulation of the Innate Immune Response in Helicobacter pylori Infection

Gastric cancer (GC) is the fifth most common cancer and the fourth most common cause of cancer-related death worldwide. The intestinal type of GC progresses from acute to chronic gastritis, multifocal atrophic gastritis, intestinal metaplasia, dysplasia, and carcinoma. Infection of the stomach by Helicobacter pylori, a Gram-negative bacterium that infects approximately 50% of the world's population, is the causal determinant that initiates the gastric inflammation and then disease progression. In this context, the induction of the innate immune response of gastric epithelial cells and myeloid cells by H. pylori effectors plays a critical role in the outcome of the infection. However, only 1% to 3% of infected patients develop gastric adenocarcinoma, emphasizing that other mechanisms regulate the localized non-specific response, including the gastric microbiota and genetic factors. This review summarizes studies describing the factors that induce and regulate the mucosal innate immune response during H. pylori infection.

Toll-Like Receptor 4 Polymorphisms (896A/G and 1196C/T) as an Indicator of COVID-19 Severity in a Convenience Sample of Egyptian Patients

Background

The clinical spectrum of COVID-19 is extremely variable. Thus, it is likely that the heterogeneity in the genetic make-up of the host may contribute to disease severity. Toll‐like receptor (TLR)-4 plays a vital role in the innate immune response to SARS-CoV-2 infection. The susceptibility of humans to severe COVID-19 concerning TLR-4 single nucleotide polymorphisms (SNPs) has not been well examined.

Objective

The goal of this research was to investigate the association between TLR-4 (Asp299Gly and Thr399Ile) SNPs and COVID-19 severity and progression as well as the cytokine storm in Egyptian patients.

Methods

We genotyped 300 adult COVID-19 Egyptian patients for TLR-4 (Asp299Gly and Thr399Ile) SNPs using PCR-restriction fragment length polymorphism (PCR-RFLP). We also measured interleukin (IL)-6 levels by enzyme-linked immunosorbent assay (ELISA) as an indicator of the cytokine storm.

Results

The minor 299Gly (G) and 399Ile (T) alleles were associated with a significant (P < 0.001) positive risk of severe COVID-19 (OR = 3.14; 95% CI = 2.02–4.88 and OR = 2.75; 95% CI = 1.66–4.57), their frequency in the severe group were 71.8% (84/150) and 70.7% (58/150), respectively. We detected significant differences between TLR-4 (Asp299Gly, Thr399Ile) genotypes with regard to serum levels of IL-6. Levels of IL-6 increased significantly with the presence of the mutant 299Gly (G) and 399Ile (T) alleles to reach the highest levels in the Gly299Gly (GG) and the Ile399Ile (TT) genotypes (170 pg/mL (145–208.25) and 112 pg/mL (24–284.75), respectively).

Conclusion

The TLR-4 (Asp299Gly and Thr399Ile) minor alleles 299Gly (G) and 399Ile (T) are associated with COVID-19 severity, mortality, and the cytokine storm.

Genetic polymorphisms in the cag pathogenicity island of Helicobacter pylori and risk of stomach cancer and high-grade premalignant gastric lesions

Helicobacter pylori (Hp) infects the stomach of about half of the human population and is strongly associated with the risk of gastric cancer (GC) and its premalignant precursors. The cag pathogenicity island (cagPAI) is a region of the Hp genome encoding for key molecular machinery involved in the infection process. Following a sequencing study, we selected 50 genetic polymorphisms located in seven cagPAI genes and tested their associations with the risk of advanced gastric premalignant lesions and GC in 1220 subjects from various Latin American populations showing the whole spectrum of phenotypes from gastritis to GC. We found that three polymorphisms of cagA are associated with the risk of advanced gastric premalignant lesions (incomplete intestinal metaplasia [ie, Type 2 and 3] or dysplasia), and that six polymorphisms located in cagA, cagL and cagI were associated with risk of GC. When corrected for multiple testing none of the associations were statistically significant. However, scores built by integrating the individual polymorphisms were significantly associated with the risk of advanced gastric premalignant lesions and GC. These results have the potential of establishing markers for risk stratification in the general population, in view of targeting Hp eradication to high-risk population groups.

Toll-like receptor 2 and 4 polymorphisms associated with Helicobacter pylori susceptibility and gastric cancer

BACKGROUND/AIMS

Genetic polymorphisms in Toll-like receptors (TLRs) are important influence on gastric lesion development and Helicobacter pylori susceptibility.

MATERIALS AND METHODS

TLR2 rs3804099 and rs3804100 and TLR4 rs10759932 were determined in a total of 400 patients. The association among genotypes and the risk of gastric lesion development and H. pylori susceptibility were evaluated by the odds ratios (ORs) and 95% confidence intervals (95% CIs) from logistic regression analyses.

RESULTS

TLR4 rs10759932, C/C homozygous genotype was associated with an increased risk of premalignant/malignant (OR=2.48, 95% CI=1.96-4.62, p=0.015). The recessive model of TLR4 rs10759932 showed a decreased risk of H. pylori susceptibility (adjusted OR=0.52, 95% CI=0.38-0.82, p=0.046). Meanwhile, the recessive model was associated with an increased risk of non-malignant (OR=3.46, 95% CI=2.25-5.67, p=0.001). In subjects with H. pylori infection, the recessive model was associated with an increased risk of non-malignant (OR=2.28, 95% CI=1.24-3.57, p=0.001) and premalignant/malignant (OR=1.83, 95% CI=1.16-2.84, p=0.027).

CONCLUSION

TLR4 rs10759932, but not TLR2 rs3804099 and rs3804100, was associated with risk of premalignant and/or malignant and H. pylori susceptibility. H. pylori infection seems to contribute to chronic gastritis, and premalignant/malignant supported the development of the premalignant/malignant lesions involved in H. pylori infection that is critical to gastric cancer in Thai patients.

Evaluation of the detection of Toll-like receptors (TLRs) in cancer development and progression in patients with colorectal cancer

Background

Toll-like receptors (TLRs) play essential role in innate and acquired immunity, are expressed in various cell types, and are associated with altered susceptibility to many diseases, and cancers. The aim of this study was to investigate TLR2 (-196 to-174del), TLR4 (Asp299Gly and Thr399Ile) and TLR9 (T1237C and T1486C) gene polymorphisms at risk of colorectal cancer (CRC) development and progression.

Methods

Peripheral blood was obtained from 397 patients with adjuvant (stage II/III, n = 202) and metastatic (n = 195) CRC. Moreover, blood samples from 50 healthy volunteers and 40 patients with adenomatous polyps were also included as control groups. DNA from patients and controls was analyzed using PCR and PCR-RFLP for genotyping functional polymorphism within TLR2, TLR4 and TLR9 genotypes.

Results

TLR2–196 to-174del/del genotype was detected in 76.6% of the patients and was significantly higher that the controls groups (p<0.001). TLR4 Asp299Gly, TLR4 Thr399Ile, TLR9 T1237C and T1486C homozygous genotypes were detected in 70.5%, 70.5%, 61.5% and 61.5% of the patients respectively, and were also significantly higher than that in the control groups (p<0.001). All polymorphisms detected were also significantly associated with the metastatic disease (p<0.001) leading to shorter overall survival (p<0.001); whereas, TLR4 Asp299Gly and Thr399Ile polymorphisms were significantly associated with KRAS mutations.

Conclusions

The detection of higher frequencies of the TLR2, TLR4 and/or TLR9 polymorphisms in CRC patients compared with the control groups highlight the role of these polymorphism in CRC development and cancer progression.

Comprehensive assessment of association between TLR4 gene polymorphisms and cancer risk: a systematic meta-analysis

Previous studies have explored the association between toll-like receptor 4 (TLR4) polymorphisms and risk of various cancers, but the results remained controversial. To obtain an assessment of the effect of TLR4 polymorphisms (rs4986790, rs4986791 and rs11536889) on cancer risk, fifty-five articles (containing 20107 cases and 28244 controls) were recruited for meta-analysis. Our result indicated that two Single Nucleotide Polymorphisms (SNP) in TLR4 were associated with decreased cancer risk for rs4986791: OR = 0.764, 95% CI: 0.652-0.894, P = 0.001 in allele model; OR = 0.769, 95%CI: 0.650-0.909, P = 0.002 in recessive model; OR = 0.505, 95% CI: 0.352-0.726, P = 0.000 in dominant model; for 11536889: OR = 0.927, 95% CI: 0.872–0.984, P = 0.013 in allele model; OR = 0.926, 95% CI: 0.862–0.944,P = 0.034 in recessive model. In terms of subgroup analyses sorted by ethnicity, only polymorphism of rs4986791 had a significant influence on decrease of cancer risk among both Caucasian and Asian populations. The findings suggested that TLR4 polymorphisms may serve as a genetic risk factor for cancers.

The Importance of Toll-like Receptors in NF-κB Signaling Pathway Activation by Helicobacter pylori Infection and the Regulators of this Response

Helicobacter pylori (H. pylori) is a common pathogenic bacterium in the stomach that infects almost half of the population worldwide and is closely related to gastric diseases and some extragastric diseases, including iron-deficiency anemia and idiopathic thrombocytopenic purpura. Both the Maastricht IV/Florence consensus report and the Kyoto global consensus report have proposed the eradication of H. pylori to prevent gastric cancer as H.pylori has been shown to be a major cause of gastric carcinogenesis. The interactions between H. pylori and host receptors induce the release of the proinflammatory cytokines by activating proinflammatory signaling pathways such as nuclear factor kappa B (NF-κB), which plays a central role in inflammation, immune response, and carcinogenesis. Among these receptors, Toll-like receptors (TLRs) are classical pattern recognition receptors in the recognition of H. pylori and the mediation of the host inflammatory and immune responses to H. pylori. TLR polymorphisms also contribute to the clinical consequences of H. pylori infection. In this review, we focus on the functions of TLRs in the NF-κB signaling pathway activated by H. pylori, the regulators modulating this response, and the functions of TLR polymorphisms in H.pylori-related diseases.

Genetic Polymorphisms of TLR4 and MICA are Associated with Severity of Trachoma Disease in Tanzania

Aim

To examine the association of TLR4 Asp299Gly and MICA exon 5 microsatellites polymorphisms with severity of trachoma in a sub-Saharan East Africa population of Tanzanian villagers.

Methods

The samples were genotyped for MICA exon 5 microsatellites and the TLR4 299 A/G polymorphism by Restriction Fragment Length Polymorphism (RFLP), and GeneScan^®, respectively. The association of TLR4 Asp299Gly and MICA exon 5 microsatellites with inflammatory trachoma (TI) and trichiasis (TI) were examined.

Results

The results showed an association between TLR4 and MICA polymorphisms and trachoma disease severity, as well as with protection. TLR4 an allele was significantly associated with inflammatory trachoma (p=0.0410), while the G allele (p=0.0410) was associated with protection.

Conclusion

TLR4 and MICA may modulate the risk of severity to trachoma disease by modulating the immune response to Ct. In addition; the increased frequency of MICA-A9 heterozygote in controls may suggest a positive selection of these alleles in adaptation to environments where Ct is endemic.

Toll-Like Receptor 4 Wild Type Homozygozity of Polymorphisms +896 and +1196 Is Associated with High Gastrin Serum Levels and Peptic Ulcer Risk

Toll-like receptor 4 is a part of the innate immune system and recognizes Helicobacter pylori lipopolysaccharide. The goal of this study was to analyze the role of Toll-like receptor 4 polymorphisms +896 (rs4986790) and +1196 (rs4986791) in the pathogenesis of Helicobacter pylori related gastroduodenal diseases in relation to gastric secretion and inflammation. Toll-like receptor 4 polymorphisms, serum gastrin-17 and pepsinogen I and II concentrations were determined, and gastroscopies with histopathological analyses were performed to 216 dyspeptic patients. As genotype controls, 179 controls and 61 gastric cancer patients were studied. In our study, the Toll-like receptor 4 +896 and +1196 polymorphisms were in total linkage disequilibrium. The homozygous wild types displayed higher gastrin-17 serum concentrations than the mutants (p = 0.001) and this effect was independent of Helicobacter pylori. The homozygous wild types also displayed an increased risk for peptic ulcers (OR: 4.390). Toll-like receptor 4 genotypes did not show any association with Helicobacter pylori positivity or the features of gastric inflammation. Toll-like receptor 4 expression was seen in gastrin and somatostatin expressing cells of antral mucosa by immunohistochemistry. Our results suggest a role for Toll-like receptor 4 in gastric acid regulation and that the Toll-like receptor 4 +896 and +1196 wild type homozygozity increases peptic ulcer risk via gastrin secretion.

Polymorphisms in TLR9 but not in TLR5 increase the risk for duodenal ulcer and alter cytokine expression in the gastric mucosa

Colonization of the gastric mucosa by Helicobacter pylori can lead to peptic ulcer and gastric adenocarcinoma. TLRs are signaling receptors involved in the recognition of microorganisms, and polymorphisms in their genes may influence the innate and adaptive immune response to H. pylori, affecting the clinical outcomes of the infection. We assessed the association between single nucleotide polymorphisms in TLR9 and TLR5 and gastroduodenal diseases. All patients were genotyped by allelic discrimination in regions 1174C>T and 1775A>G of TLR5 and -1237T>C and 2848G>A of TLR9. The 2848A allele of TLR9 was more frequent in duodenal ulcer and showed an association of risk with this pathology. Polymorphisms in TLR5 were not found to be associated with disease. Patients with polymorphisms in TLR9 and TLR5 expressed significantly lower levels of IL-1β and TNF-α, whereas polymorphisms in TLR5 also decreased the expression of IL-6 and IL-10. Our findings suggest that 2848G>A polymorphism in TLR9 increases the risk for the development of duodenal ulcer probably by modifying the inflammatory response to H. pylori infection. This is the first study to show an association of 2848A allele of TLR9 with duodenal ulcer and with altered expression of inflammatory cytokines in the gastric mucosa.

Association of TLR5 gene polymorphisms in ulcerative colitis patients of north India and their role in cytokine homeostasis

Background and Aim

In health, TLR signaling protects the intestinal epithelial barrier and in disease, aberrant TLR signaling stimulates diverse inflammatory responses. Association of TLR polymorphisms is ethnicity dependent but how they impact the complex pathogenesis of IBD is not clearly defined. So we propose to study the status of polymorphisms in TLR family of genes and their effect on cytokines level in UC patients.

Methods

The genotypes of the six loci TLR1-R80T, TLR2-R753Q, TLR3-S258G, TLR5-R392X, TLR5-N592S and TLR6-S249P were determined in 350 controls and 328 UC patients by PCR-RFLP and sequencing. Cytokine levels were measured by ELISA in blood plasma samples. Data were analyzed statistically by SPSS software.

Results

TLR5 variants R392X and N592S showed significant association (p = 0.007, 0.021) with UC patients but TLR 1, 2, 3, 6 variants did not show any association. Unlike other studies carried out in different ethnic groups, TLR 6 (S249P) SNP was universally present in our population irrespective of disease. Genotype-phenotype correlation analysis revealed that the patients having combination of multiple SNPs both in TLR5 and TLR4 gene suffered from severe disease condition and diagnosed at an early age. The level of TNFα (p = 0.004), IL-6 (p = 0.0001) and IFNγ (p = 0.006) significantly increased in patients as compared to controls having wild genotypes for the studied SNPs. However, there was decreased level of TNFα (p = 0.014), IL-6 (p = 0.028) and IFNγ (p = 0.001) in patients carrying TLR5-R392X variant as compared to wild type patients. Patients carrying two simultaneous SNPs D299G in TLR4 gene and N592S in TLR5 gene showed significant decrease in the levels of TNFα (p = 0.011) and IFNγ (p = 0.016).

Conclusion

Polymorphisms in TLR 5 genes were significantly associated with the UC in North Indian population. The cytokine level was significantly modulated in patients with different genotypes of TLR4 and TLR5 SNPs.

Toll-like receptor gene polymorphisms and susceptibility to Epstein-Barr virus-associated and -negative gastric carcinoma in Northern China

BACKGROUND/AIMS

Various polymorphisms in toll-like receptor (TLR) genes have been identified and associated with susceptibility to various malignancies, such as gastric carcinoma (GC), breast cancer, and prostate cancer. However, little is known about the polymorphisms of TLR genes and the susceptibility to GC in Northern China, especially to Epstein-Barr virus-associated GC (EBVaGC). We focused on the association with susceptibility to GC, especially to EBVaGC.

PATIENTS AND METHODS

Polymorphisms of the TLR2, 3, 4, and 9 genes were measured in 52 cases of EBVaGC and 157 cases of EBV-negative GC (EBVnGC). Ninety-four peripheral blood samples from healthy individuals were also examined.

RESULTS

For the TLR2 gene (196 to 174 del), there was no significant difference between the GC group and control group in genotype, but there was a significant difference in the del allele. As for the TLR3 gene (c. 1377C/T), there were significant differences between the GC group and the control group in both genotype and allelic frequency. No SNPs single nucleotide polymorphisms (SNPs) were found in the TLR4 gene at the sites Asp299Gly and Thr399Ile. As for TLR9 1486T/C (rs187084) and C2848T (rs352140), there was also no association between the GC group and control. In all of the indicators, there were no significant differences between EBVaGCs and EBVnGCs.

CONCLUSIONS

The TLR3 gene (c. 1377C/T) polymorphisms and the del allele of the TLR2 gene ( 196 to 174) were both associated with susceptibility to GC in Shangdong Province of Northern China. There was no interaction between EBV and TLR gene polymorphisms in EBVaGC.

Association between TLR4 (+896A/G and +1196C/T) polymorphisms and gastric cancer risk: an updated meta-analysis

BACKGROUND

Toll-like receptor 4 (TLR4) is a receptor of lipopolysaccharide in the signaling transduction of gastric epithelial cell. It plays a pivotal role in activation of innate immunity and pathogen recognition and thus acts as a modulator in the development and progression of gastric cancer. Growing studies explored the association of polymorphisms in TLR4 with susceptibility to gastric cancer, but the results have remained controversial and conflicting. To investigate the effect of two selected TLR4 (+896A/G and +1196C/T) polymorphisms on gastric cancer, we performed a meta-analysis.

METHODS

A comprehensive search was conducted to identify all eligible case-control publications investigating the association between TLR4 polymorphisms and gastric cancer risk. Odds ratios (OR) and corresponding 95% confidence intervals (CI) were used to assess such association.

RESULTS

Up to March 26 2014, 10 published case-control studies from PubMed and EMBase were available, involving a total of 1888 gastric cancer patients and 3433 control subjects. In the overall meta-analyses, a significantly increased gastric cancer risk was detected in TLR4 +896A/G polymorphism (heterozygous model, AG vs. AA: OR = 1.67, 95% CI, 1.39-2.01; additive model, G vs. A: OR = 1.64, 95% CI, 1.37-1.95) and TLR4 +1196C/T polymorphism (heterozygous model, CT vs. CC: OR = 1.42, 95% CI, 1.11-1.81; additive model, T vs. C: OR = 1.36, 95% CI, 1.08-1.72), similar results were obtained in the subgroup analyses of Caucasian, whereas no associations were detected in any genetic models of non-Caucasian.

CONCLUSIONS

The overall results suggest that TLR4 polymorphisms (+896A/G and +1196C/T) may be associated with a significantly increased gastric cancer risk in Caucasian.

Effect of the -2081G/A polymorphism of the TLR4 gene and its interaction with Helicobacter pylori infection on the risk of gastric cancer in Chinese individuals

AIMS

Toll-like receptor 4 (TLR4) plays an important role in gastric carcinoma. Using a case-control study, we analyzed the genotypic distribution of TLR4 rs10983755 (-2081G/A) and rs11536878 in a Chinese population and investigated the effect of their interactions with Helicobacter pylori infection on susceptibility to gastric cancer (GC) and atrophic gastritis (AG).

METHODS

In this study, 409 and 581 cases of GC and AG, respectively, were selected for analyses along with an equal number of matched controls. The TLR4 polymorphisms were genotyped using Sequenom MassARRAY. Serum levels of anti-H. pylori IgG were determined by enzyme-linked immunosorbent assay.

RESULTS

The TLR4-2081G/A polymorphism was negatively associated with GC (AG+AA vs. GG: odds ratio [OR]=0.70, 95% confidence interval [CI]=0.53-0.93, p=0.012). A decreased risk of GC was observed in H. pylori negative and TLR4-2081(AG+AA) genotype subjects [H. pylori(-)/AG+AA vs. H. pylori(+)/GG: OR=0.16, 95% CI=0.09-0.27, p<0.001]. The rs11536878 polymorphism was not associated with GC or AG.

CONCLUSIONS

The TLR4-2081G/A polymorphism seems to affect the risk of gastric carcinogenesis and may to some degree play a protective role against H. pylori infection.

Pattern-recognition receptors and gastric cancer

Chronic inflammation has been associated with an increased risk of several human malignancies, a classic example being gastric adenocarcinoma (GC). Development of GC is known to result from infection of the gastric mucosa by Helicobacter pylori, which initially induces acute inflammation and, in a subset of patients, progresses over time to chronic inflammation, gastric atrophy, intestinal metaplasia, dysplasia, and finally intestinal-type GC. Germ-line encoded receptors known as pattern-recognition receptors (PRRs) are critical for generating mature pro-inflammatory cytokines that are crucial for both Th1 and Th2 responses. Given that H. pylori is initially targeted by PRRs, it is conceivable that dysfunction within genes of this arm of the immune system could modulate the host response against H. pylori infection, and subsequently influence the emergence of GC. Current evidence suggests that Toll-like receptors (TLRs) (TLR2, TLR3, TLR4, TLR5, and TLR9), nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) (NOD1, NOD2, and NLRP3), a C-type lectin receptor (DC-SIGN), and retinoic acid-inducible gene (RIG)-I-like receptors (RIG-I and MDA-5), are involved in both the recognition of H. pylori and gastric carcinogenesis. In addition, polymorphisms in genes involved in the TLR (TLR1, TLR2, TLR4, TLR5, TLR9, and CD14) and NLR (NOD1, NOD2, NLRP3, NLRP12, NLRX1, CASP1, ASC, and CARD8) signaling pathways have been shown to modulate the risk of H. pylori infection, gastric precancerous lesions, and/or GC. Further, the modulation of PRRs has been suggested to suppress H. pylori-induced inflammation and enhance GC cell apoptosis, highlighting their potential relevance in GC therapeutics. In this review, we present current advances in our understanding of the role of the TLR and NLR signaling pathways in the pathogenesis of GC, address the involvement of other recently identified PRRs in GC, and discuss the potential implications of PRRs in GC immunotherapy.

Associations of a TLR4 single-nucleotide polymorphism with H. pylori associated gastric diseases in Iranian patients

OBJECTIVE

Helicobacter pylori (H. pylori) is associated with gastric ulcer and gastric adenocarcinoma. Polymorphisms in the host genes coding for toll-like receptors (TLRs) may influence the innate and adaptive immune response to the infection, affecting the susceptibility to H. pylori or the disease outcomes. But the details and association to different polymorphisms and different clinical expressions in patients infected with H. pylori (different clinical expression of H. pylori infection) remain unclear.

METHODS

A case-control study consisting of 195 patients with H. pylori infection and 241 H. pylori uninfection was conducted. Genomic DNA was extracted and genotypes of TLR4Asp299Gly polymorphism were assessed through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Presence of cagA was evaluated using PCR.

RESULTS

TLR4 (Asp299Gly) G and DG alleles frequency in H. pylori infected population was significantly higher in the chronic gastritis group than in the chronic active gastritis group (P=0.021; OR, 2.409; 95% CI, 1.124-5.162). Grade mononuclear (MN) infiltration in H. pylori infected patients with DG genotype of TLR-4 Asp299Gly increased significantly. CagA positivity was more frequently associated with chronic active gastritis (P=0.017, OR=2.26, 95% CI=1.144-4.462) and grade polymorphonucler (PMN) infiltration.

CONCLUSION

TLR-4 Asp299Gly G allele substitution may be modified pattern of immune response in the gastric mucosa of H. pylori infected patients and may be H. pylori infected patients with gastritis have increased risk for the development of chronic gastritis. CagA positivity may be a risk factor for development of gastritis.

Toll-like receptor 4 single-nucleotide polymorphisms Asp299Gly and Thr399Ile in ovarian cancers

Toll-like receptor (TLR4) 4 is present in numerous cell types and serves as the first point of defense in the innate immune system. Single-nucleotide polymorphisms (SNPs) are present in a number TLR genes and have been associated with various infection and inflammation disorders. Asp299Gly and Thr399Ile, TLR4 SNPs, are associated with tumor progression. In the present study, cases of ovarian cancer were analyzed with regards to Asp299Gly and Thr399Ile of the TLR4 gene. Genotype analysis was performed using DNA from tissue samples from stage I–IV patients with ovarian cancer. DNA from tissue samples was extracted and analyzed by a pyrosequencing method following multiplex polymerase chain reaction. The genotypes of these SNPs were analyzed in the present study in a population of 105 patients, with different types of ovarian cancer, between 2004 and 2012. The allele frequencies for TLR4 Asp299Gly identified in this population were 1.00 (A) and 0.00 (G); for TLR4 Thr399Ile the allele frequencies were; 1.00 (C) and 0.00 (T). For TLR4 Asp299Gly the observed genotype frequency was 1.00 (AA), 0.00 (AG) and 0.0 (GG). In TLR4 Thr399Ile the observed genotype frequencies were 1.00 (CC), 0.00 (CT) and 0.00 (TT). TLR4 Asp299Gly and Thr399Ile alleles were not detected in the patients. These results indicated that the TLR4 299Gly and 399Ile alleles were exhibited at a lower frequency in the ovarian cancer patients that were examined.

Role of gene polymorphisms in gastric cancer and its precursor lesions: Current knowledge and perspectives in Latin American countries

Latin America shows one of the highest incidence rates of gastric cancer in the world, with variations in mortality rates among nations or even within countries belonging to this region. Gastric cancer is the result of a multifactorial complex process, for which a multistep model of carcinogenesis is currently accepted. Additionally to the infection with Helicobacter pylori, that plays a major role, environmental factors as well as genetic susceptibility factors are significant players at different stages in the gastric cancer process. The differences in population origin, demographic structure, socio-economic development, and the impact of globalization lifestyles experienced in Latin America in the last decades, all together offer opportunities for studying in this context the influence of genetic polymorphisms in the susceptibility to gastric cancer. The aim of this article is to discuss current trends on gastric cancer in Latin American countries and to review the available published information about studies of association of gene polymorphisms involved in gastric cancer susceptibility from this region of the world. A total of 40 genes or genomic regions and 69 genetic variants, 58% representing markers involved in inflammatory response, have been used in a number of studies in which predominates a low number of individuals (cases and controls) included. Polymorphisms of IL-1B (-511 C/T, 14 studies; -31 T/C, 10 studies) and IL-1RN (variable number of tandem repeats, 17 studies) are the most represented ones in the reviewed studies. Other genetic variants recently evaluated in large meta-analyses and associated with gastric cancer risk were also analyzed in a few studies [e.g., prostate stem cell antigen (PSCA), CDH1, Survivin]. Further and better analysis centered in gene polymorphisms linked to other covariates, epidemiological studies and the information provided by meta-analyses and genome-wide association studies should help to improve our understanding of gastric cancer etiology in order to develop appropriate health programs in Latin America.

Use of the cockroach antigen model of acute asthma to determine the immunomodulatory role of early exposure to gastrointestinal infection

The increased incidence of asthma over the last 50 years in developed countries has been associated with a decrease in infections acquired early in childhood. These early infections are thought to shape subsequent immune responses. Although there have been multiple clinical associations between gastrointestinal infections and decreased asthma incidence, it has been difficult to move beyond a simple correlation when studying human patients. This section describes an acute asthma model in C57BL/6 mice designed to specifically evaluate the effect of prior gastric Helicobacter colonization and inflammation in a murine model of cockroach allergen-induced asthma.

Polymorphisms of Helicobacter pylori signaling pathway genes and gastric cancer risk in the European Prospective Investigation into Cancer-Eurgast cohort

Helicobacter pylori is a recognized causal factor of noncardia gastric cancer (GC). Lipopolysaccharide and peptidoglycan of this bacterium are recognized by CD14, TLR4 and NOD2 human proteins, while NFKB1 activates the transcription of pro-inflammatory cytokines to elicit an immune response. Single nucleotide polymorphisms (SNPs) in these genes have been associated with GC in different populations. We genotyped 30 SNPs of these genes, in 365 gastric adenocarcinomas and 1,284 matched controls from the European Prospective Investigation into Cancer cohort. The association with GC and its histological and anatomical subtypes was analyzed by logistic regression and corrected for multiple comparisons. Using a log-additive model, we found a significant association between SNPs in CD14, NOD2 and TLR4 with GC risk. However, after applying the multiple comparisons tests only the NOD2 region remained significant (p = 0.009). Analysis according to anatomical subtypes revealed NOD2 and NFKB1 SNPs associated with noncardia GC and CD14 SNPs associated with cardia GC, while analysis according to histological subtypes showed that CD14 was associated with intestinal but not diffuse GC. The multiple comparisons tests confirmed the association of NOD2 with noncardia GC (p = 0.0003) and CD14 with cardia GC (p = 0.01). Haplotype analysis was in agreement with single SNP results for NOD2 and CD14 genes. From these results, we conclude that genetic variation in NOD2 associates with noncardia GC while variation in CD14 is associated with cardia GC.

Association of TLR2 and TLR4 polymorphisms with risk of cancer: a meta-analysis

BACKGROUNDS

The activation of Toll-like receptors (TLRs) may be an important event in the immune evasion of tumor cell. Recently, numerous studies have investigated the associations between TLR2 -196 to -174 del and two SNPs of TLR4 (rs4986790 and rs4986791) and the susceptibility to different types of cancer; however, the results remain conflicting. The aim of this study was to assess the association between TLR2 and TLR4 polymorphisms and cancer risk in a meta-analysis with eligible published studies.

METHODOLOGY/PRINCIPLE FINDINGS

A dataset composed of 14627 cases and 17438 controls from 34 publications were included in a meta-analysis to evaluate the association between overall cancer risk or cancer-specific risk and three SNPs of TLRs (TLR2 -196 to -174 del, TLR4 rs4986790 and rs4986791). The results showed that all of these three polymorphisms were significantly associated with the increased cancer risk (dominant model: OR = 1.64, 95% CI: 1.04-2.60 for TLR2 -196 to -174 del; OR = 1.19, 95% CI: 1.01-1.41 for TLR4 rs4986790; and OR = 1.47, 95% CI: 1.120-1.80 for TLR4 rs4986791; respectively). In stratified analysis, we found the effect of TLR2 -196 to -174 del on cancer risk remained significant in the subgroup of Caucasians and South Asians, but not in East Asians. However, the association between rs4986791 and cancer risk was significant in both South Asians and East Asians, but not in Caucasians. Furthermore, the association between rs4986790 and cancer risk was statistically significant in digestive cancers (dominant model: OR = 1.76, 95% CI: 1.13-2.73) and female-specific cancers (dominant model: OR = 1.50, 95% CI: 1.16-1.94). However, no significant association with risk of digestive system cancers was observed for TLR2 -196 to -174 del and TLR4 rs4986791.

CONCLUSIONS/SIGNIFICANCE

This meta-analysis presented additional evidence for the association between TLR2 and TLR4 polymorphisms and cancer risk. Further well-designed investigations with large sample sizes are required to confirm this conclusion.

TLR4 polymorphisms associated with developing gastric pre-cancer lesions in a Chinese Han population

Helicobacter pylori infection is a risk factor for gastric cancer. In addition, toll-like receptor 4 (TLR4) plays a fundamental role in pathogen recognition and activation of innate immunity. This study investigated the association of TLR4 polymorphisms with a risk of intestinal metaplasia (IM) and intraepithelial neoplasia (IN) in a Chinese Han population. This study analyzed TLR4 gene polymorphisms in 333 patients (IM, 193 cases; IN, 140 cases) and 312 atypia-free controls in a Chinese Han population using a Taqman allelic discrimination assay. The TLR4 single nucleotide polymorphisms +896A/G and +1196C/T were not associated with the risk of IM or IN. However, the single-locus analysis showed that the C allele of TLR4+2856T/C had significantly reduced risk of IM and IN [adjusted odds ratio (OR)=0.42; 95%CI=0.29-0.62 and OR=0.62; 95%CI=0.41-0.93, respectively] compared with the wild-type homozygote (TT). The frequencies of TLR4+2856T/C TC and T carrier were significantly lower in patients with Sydney's slight IM and low grade IN (P<0.01 and P=0.01, respectively), while the TC genotype showed a lower risk of moderate IM compared to healthy controls (P=0.045). In addition, the data revealed that H. pylori infection, heavy alcohol consumption and high salt uptake were associated with a higher susceptibility for developing this neoplasm. TLR4 rs10759932 TC and C carriers were associated with a lower risk in developing precancerous lesions in the stomach in a Chinese Han population.

Should a Toll-like receptor 4 (TLR-4) agonist or antagonist be designed to treat cancer? TLR-4: its expression and effects in the ten most common cancers

Toll-like receptor 4 (TLR-4) is well known for its host innate immunity. Despite the fact that TLR-4 activation confers antitumor responses; emerging evidence suggests that TLR-4 is associated with tumor development and progression. It is now clear that overactivation of TLR-4, through various immune mediators, may cause immune response dysfunction, resulting in tumorigenesis. Different cancers could have different extents of TLR-4 involvement during tumorigenesis or tumor progression. In this review, we focus on infection- and inflammation-related TLR-4 activation in noncancer and cancer cells, as well as on the current evidence about the role of TLR-4 in ten of the most common cancers, viz, head and neck cancer, lung cancer, gastrointestinal cancer, liver cancer, pancreatic cancer, skin cancer, breast cancer, ovarian cancer, cervical cancer, and prostate cancer.

Associations between the four toll-like receptor polymorphisms and the risk of gastric cancer: a meta-analysis

PURPOSE

The association between Toll-like receptor 2 (TLR2) -196 to -174del polymorphism and Toll-like receptor 4 (TLR4) polymorphisms (Asp299Gly, Thr399Ile, and 3725G>C) and gastric cancer risk are still conflicting. For better understanding of the effects of these four polymorphisms on gastric cancer risk, a meta-analysis was performed.

METHODS

An extensive search was performed to identify all case-control studies investigating such associations. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the relationship.

RESULTS

A total of 21 studies (3,436 cases and 4,239 controls) were found to be eligible for meta-analysis. In the overall analysis, a significantly increased risk was observed in TLR4 Asp299Gly polymorphism (G allele vs. A allele: OR=1.84, 95%CI: 1.41, 2.39; GA vs. AA: OR=1.89, 95%CI: 1.43, 2.48; Recessive model: OR=1.90, 95%CI: 1.44, 2.49) and TLR4 Thr399Ile polymorphism (T allele vs. C allele: OR=1.97, 95%CI: 1.22, 3.18; TC vs. CC: OR=1.94, 95%CI: 1.19, 3.15; Recessive model: OR=1.98, 95%CI: 1.21, 3.21), whereas no associations were found in any genetic models of TLR2 -196 to -174del and TLR4 3725G>C polymorphisms. Similar results were found in the subgroup analyses by ethnicity. However, we detected that A allele carriers of the TLR4 Asp299Gly polymorphism might have an increase risk of gastric cancer in the Helicobacter pylori-positive population (G allele vs. A allele: OR=2.01, 95%CI: 1.22, 3.31).

CONCLUSION

The results of this meta-analysis indicate that the TLR4 Asp299Gly and Thr399Ile polymorphisms are risk factors for gastric cancer development.

Positive association between Toll-like receptor 4 gene +896A/G polymorphism and susceptibility to gastric carcinogenesis: a meta-analysis

Several studies have investigated the association between the Toll-like receptor 4 (TLR4) gene +896A/G polymorphism and gastric carcinogenesis, including gastric cancer and precancerous gastric lesions. However, published results are inconsistent. So, we performed a meta-analysis to assess whether the TLR4 +896A/G single-nucleotide polymorphism (SNP) is a risk factor in gastric cancer development. We searched PubMed and Embase databases for studies that reported the odds ratio (OR) and 95 % confidence interval (CI) for the association between the TLR4 +896A/G SNP and the risk of gastric cancer and/or precancerous lesions with the last update of November 2012. Data were analyzed using Review Manager (Version 5.1), and publication bias was estimated. We included 10 study populations, comprising 2,233 cases and 2,849 controls from 8 publications. The pooled OR was 2.00 (95 % CI = 1.59-2.53) for the G allelic model. Analysis stratified by different stages and anatomic sites of neoplasia resulted in a significantly increased risk associated with gastric cancer (OR = 1.87, 95 % CI = 1.44-2.44), especially the non-cardia subtype (OR = 2.03, 95 % CI = 1.51-2.72). Besides, the G allele emerged as a strong risk factor for precancerous gastric lesions (OR = 2.47, 95 % CI = 1.57-3.88). A subsequent subgroup analysis by Helicobacter pylori-positive ratio in cases (>80 %) indicated an enhancement in the association with precancerous lesions (OR = 3.43, 95 % CI = 1.92-6.13). The TLR4 +896A/G SNP is a risk factor in gastric carcinogenesis, especially in H. pylori-infected patients with precancerous lesions.

A 5'-flanking region polymorphism in toll-like receptor 4 is associated with gastric cancer in a Chinese population

Objective

Inflammation induced by H.pylori colonization in the stomach is related to the development of gastric cancer and the genetic variations of the genes involved in the immune responses modify the host response to the infection. The aim of this study was to evaluate whether polymorphisms in the toll-like receptor 4 (TLR4) gene, a key regulator of both innate and adaptive immunity, were related to the susceptibility to gastric cancer in a Chinese population.

Methods

Two variations in the 5′-flanking region of TLR4 (rs1927914 T > C and rs10759932 T > C) were genotyped by using the PCR-restriction fragment length polymorphism (RFLP) assay in a case-control study of 1,053 incident gastric cancer cases and 1,100 cancer-free controls in a Chinese population.

Results

Individuals carrying the C allele of rs10759932 had a significantly reduced risk of gastric cancer (adjusted OR = 0.81; 95%CI = 0.67-0.96), compared with the wild-type homozygote (TT), and the protective effect was not significantly different among subgroups stratified by age, sex, smoking, drinking and H.pylori infection status (P for heterogeneity > 0.05). No significant association was observed between rs1927914 and gastric cancer risk in this study population.

Conclusion

The T to C allele substitution of rs10759932 may play a protective role in gastric carcinogenesis in a Chinese population. Large studies with different ethnic populations are warranted to confirm these findings.

Helicobacter pylori induces increased expression of Toll-like receptors and decreased Toll-interacting protein in gastric mucosa that persists throughout gastric carcinogenesis

BACKGROUND

Toll-like receptors (TLR) are essential for Helicobacter pylori (HP) recognition. Their role in the progression of gastric lesions leading to cancer is not established.

AIM

To evaluate for the first time in humans the expression of TLR2, TLR4, and TLR5, as well as the expression of other related molecules in the entire sequence of gastric lesions.

METHODS

Biopsy samples (n = 80, 48% HP+) from normal mucosa, HP gastritis, metaplasia, dysplasia or adenocarcinoma were obtained from 44 patients. mRNA quantification of TLR2, TLR4, TLR5, Toll-interacting protein (TOLLIP), PPAR-γ, NF-κB, TNF-α, COX-1, COX-2, and CDX-2 was performed by real-time RT-PCR. TLR2, TLR4, and TLR5 protein expression was quantified by immunohistochemistry.

RESULTS

When compared to normal mucosa (1.0 arbitrary unit (AU)), HP gastritis presented higher expression of TLR2 (2.23 ± 0.36 AU), TLR4 (1.92 ± 0.40 AU) and TNF-α (2.14 ± 0.50 AU) and lower TOLLIP and PPARγ expression (0.72 ± 0.12 AU, p < .05 all genes). Metaplasia and dysplasia/carcinoma presented higher expression of TLR2 (1.66 ± 0.46 and 1.48 ± 0.20 AU, respectively, p < .05), lower expression of TOLLIP (0.66 ± 0.09 and 0.52 ± 0.04 AU, p < .05) and PPARγ (0.73 ± 0.12 and 0.63 ± 0.10 AU, p < .05). The significant trend for decrease in TOLLIP and PPARγ was associated with increasing levels of CDX-2 from normal mucosa to carcinoma (p < .05), translating that in diffuse and higher TLRs protein expression (p < .05).

CONCLUSION

Gastric carcinogenesis is associated with decreasing levels of TLRs inhibitors and elevated TLRs levels throughout all the spectrum of lesions. Future studies should investigate if modulation of these receptors activity may influence gastric carcinogenesis and tumor progression.

Time trends in epidemiology of peptic ulcer disease in India over two decades

BACKGROUND

Epidemiology of peptic ulcer disease (PUD) in India differs from that in the West. It may have undergone a change with recent improvement in hygiene and availability of potent antisecretory and ulcerogenic drugs. We therefore tried to assess time-trends in the frequency of PUD over the past two decades.

METHODS

Records of patients with uninvestigated dyspepsia and no alarm symptoms who had undergone upper gastrointestinal endoscopy at our institution during the years 1988 (n = 2,358), 1992 (n = 2,240), 1996 (n = 5,261), 2000 (n = 7,051), 2004 (n = 5,767) and 2008 (n = 7,539) were retrospectively reviewed. The frequencies of duodenal and gastric ulcer disease in these groups were compared.

RESULTS

Of the 30,216 patients (age:41.7±12.7 years, 34 % females) during the six study periods, 2,360 (7.8 %) had PUD. The frequencies of both duodenal ulcer and gastric ulcer showed a decline from 1988 to 2008, i.e. from 12 % to 2.9 % and 4.5 % to 2.7 %, respectively (p-value <0.001 for trend for each). The decline was more marked for duodenal ulcer, and the ratio of duodenal to gastric ulcer declined from 2.7 in 1988 to 1.1 in 2008.

CONCLUSIONS

The epidemiology of PUD in India may have changed in the past two decades with the incidence of duodenal ulcer declining more rapidly than that of gastric ulcer.

Polymorphisms of the TLR2 and TLR4 genes are associated with risk of gastric cancer in a Brazilian population

AIM: To investigate toll-like receptor 2 (TLR2) -196 to -174 del, and TLR4 (+896A/G rs4986790 and +1196C/T rs4986791) polymorphisms at risk of chronic gastritis and gastric cancer in a Brazilian population and association of gastric lesions with risk factors such as smoking, alcohol intake and Helicobacter pylori infection.

METHODS: In this case-control study, polymorphism at TLR2 -196 to -174 del was investigated by using the allele-specific polymerase chain reaction (PCR) method, while the PCR-restriction fragment length polymorphism technique was carried out to identify the TLR4 (rs4986790 and rs4986791) genotypes in 607 Brazilian individuals (208 with chronic gastritis-CG, 174 with gastric cancer-GC and 225 controls -C).

RESULTS: The single nucleotide polymorphisms TLR4+1196C/T was not associated with risk of chronic gastritis or gastric cancer and the homozygous genotypes TLR4+896GG and TLR4+1196TT were absent in the studied population. However, the frequency of TLR2 -196 to -174 ins/del + del/del and TLR4+896AG genotypes was significantly higher (P < 0.01 and P = 0.01, respectively) in the cancer group (33.4% and 11.5%, respectively) than in the control group (16.9% and 4.5%, respectively). It was also observed that the G-C haplotype of the TLR4+896A/G+1196C/T (P = 0.02) and the combination of variant alleles of the TLR2/TLR4+896G (P = 0.02) are associated with susceptibility to gastric cancer. In addition, the multiple logistic regression showed that male gender [odds ratio (OR) = 2.70; 95% CI: 1.66-4.41; P < 0.01], alcohol intake (OR = 2.93; 95% CI: 1.76-4.87; P < 0.01), TLR2 -196 to -174 del (OR = 2.64; 95% CI: 1.56-4.44; P < 0.01) and TLR4+896G (OR = 3.19; 95% CI: 1.34- 7.61; P < 0.01) polymorphisms were associated with a higher susceptibility to developing this neoplasm.

CONCLUSION: Our data indicate that TLR2 -196 to -174 del and TLR4+896G may increase the risk of gastric cancer in a Brazilian population.

Toll-like receptor 4 Asp299Gly and Thr399Ile polymorphisms in cancer: a meta-analysis

Toll-like receptor 4 (TLR4) is critical in the recognition of Gram-negative bacteria serving as a key immune system effector. Recently, a number of case-control studies were conducted to investigate the association between TLR4 gene polymorphism and cancer risk, especially Asp299Gly and Thr399Ile polymorphisms. However, published data were still conflicting. In this paper, we summarized 9463 cancer cases and 10,825 controls from 22 studies and attempted to assess the susceptibility of TLR4 gene polymorphism to cancers by a synthetical meta-analysis. Odds ratios (ORs) with 95% confidence intervals (CIs) were estimated to assess the relationship. Our results suggested that Asp299Gly represented a risk factor on cancers in digestive system (G allele versus A allele, OR=1.64, 95% CI: 1.02-2.64; GA+GG versus AA, OR=1.64, 95% CI: 1.00-2.71) but tend to have a protective effect on prostate cancer (GG versus AA, OR=0.37, 95% CI: 0.14-0.98; GG versus GA+AA, OR=0.37, 95% CI: 0.14-0.98). Thr399Ile polymorphism was significantly associated with an elevated cancer risk in overall analysis (T allele versus C allele, OR=1.72, 95% CI: 1.27-2.33; TC versus CC, OR=1.63, 95% CI: 1.18-2.26; TT+TC versus CC, OR=1.70, 95% CI: 1.24-2.34) and especially in gastrointestinal subgroup (T allele versus C allele, OR=2.01, 95% CI: 1.40-2.89; TC versus CC, OR=1.86, 95% CI: 1.26-2.74; TT+TC versus CC, OR=1.97, 95% CI: 1.35-2.88). Further prospective researches with larger numbers of worldwide participants are warranted to draw comprehensive and true conclusions.

Cytokine and chemokine modification by Toll-like receptor polymorphisms is associated with nasopharyngeal carcinoma

Toll-like receptors (TLR) play a pivotal role in sensing a wide range of pathogens, including bacteria, fungi and viruses. A dysregulation of TLR signaling may increase the risk of developing chronic inflammatory diseases and cancers. The aim of this study was to investigate the association of TLR2 R753Q, TLR4 D299G, and T399I polymorphisms with nasopharyngeal carcinoma (NPC) and to explore the effects of these polymorphisms on cytokine and chemokine expression in NPC biopsies. The genotypes of the three loci among 236 patients with NPC and 287 healthy controls were determined by PCR-RFLP. Cytokines and chemokines mRNA and protein in NPC biopsies were measured by real-time quantitative PCR and ELISA, respectively. Results showed that the combined CT/TT genotype of T399I was associated with increased NPC risk, with an odds ratio of 1.853 (95% confidence interval: 1.184-2.961). Also, individuals with the T allele of T399I showed a 1.842-fold increase in NPC risk compared to those with the T399I C allele (95% confidence interval: 1.213-3.015). Messenger RNA levels of interleukin (IL)-1α, tumor necrosis factor-α and IL-10 were significantly elevated in patients with T399I combined CT/TT genotype; IL-1α and IL-10 protein concentration significantly increased in NPC patients with T399I combined CT/TT genotype compared to those with the T399I CC genotype. Our data suggest that TLR4 T399I modify cytokines and chemokines patterns and play a role in the development of NPC.

TLR4 polymorphisms and disease susceptibility

Toll-like receptors (TLRs) play a central role in the regulation of the host immune system. Each TLR recognizes specific pathogen-associated molecular patterns (PAMPs). TLR4 is one of the well characterized pathogen recognition receptors (PRRs) that recognizes the lipopolysaccharide (LPS) of Gram-negative bacteria, some conserved structures from fungal to mycobacterial pathogens and some endogenous ligands. A complex signaling cascade initiates after the ligand binds to the TLR4 ectodomain, leading to the activation of multiple inflammatory genes. Genetic variations greatly influence immune responses towards pathogenic challenges and disease outcome. In this review, we summarize various reports regarding TLR4 polymorphisms and disease susceptibility.

Increased expression of toll-like receptors (TLR) 2, 4 and 5 in gastric dysplasia

TLRs are important innate immunity receptors. Even though TLR2, 4 and 5 appear to be important for Helicobacter pylori (HP) recognition, their role in the evolution of gastritis to more advanced lesions is still unknown. To compare the expression of TLR2, 4 and 5 in normal gastric mucosa, HP+ gastritis, intestinal metaplasia, dysplasia and adenocarcinoma. Immunohistochemistry for TLR2, 4 and 5 was performed with anti-TLR2-TLR4-TLR5 antibodies in 117 histological samples of normal gastric mucosa (n = 22), HP+ gastritis (n = 20), intestinal metaplasia (n = 33), dysplasia (mucosectomy specimens, n = 20) and intestinal type adenocarcinoma (surgery specimens,n = 22); quantification of expression was performed independently by two pathologists taking into account the percentage of positive epithelial cells and the degree of expression (zero to three score). A statistically significant trend for progressive increase of TLRs expression from normal mucosa to gastric dysplasia was found (mean expression: normal mucosa 0.1; gastritis 1.0; metaplasia 2.2; dysplasia 2.8, p < 0.01). All dysplasia samples presented more than 90% positive epithelial cells with strong expression (2.8;95%CI2.7-3). There was less TLRs expression in carcinomas (TLR2:1.0; TLR4:2.0 and TLR5:1.2, p < 0.05) when compared with dysplasia, with TLR4 being more expressed than TLR2 and 5 in these lesions (p = 0.03). A score of all markers' expression of eight leads to a low (4%) false positive rate in patients with precancerous conditions. Progression of gastric lesions associated with gastric carcinogenesis is associated with increased TLRs expression. Gastric dysplasia presents a high level of TLRs expression, suggesting that these receptors may play a role in adenocarcinoma development.

Impact of Toll-like receptor 4 polymorphisms on risk of cancer

Toll-like receptor 4 (TLR4) is one of the key immune system effectors playing the main role in recognition of viruses and bacteria. Dysregulation of the TLR4 signaling owing to single nucleotide polymorphisms (SNPs) may alter the ligand binding and balance between pro- and anti-inflammatory cytokines, thereby modulating the risk of chronic inflammation and cancer. TLR4 polymorphisms may be associated with at least nine types of cancer. The most intensively investigating TLR4 polymorphisms are Asp299Gly (rs4986790) and Thr399Ile (rs4986791). It seems to be that Asp299Gly and Thr399Ile are related to increased risk of precancerous gastric lesions, and, possibly, gastric cancer. Thr399Ile also may be connected with gallbladder cancer, and both of these polymorphisms apparently have no impact on risk of prostate cancer. However, the data about many SNPs and their associations with different types of cancer are conflicting, and further large, well-designed, comprehensive studies in various populations are necessary for solution of this problem. The short list of TLR4 SNPs for further investigation may include TLR4_896A/G (Asp299Gly, rs4986790), TLR4_1196C/T (Thr399Ile, rs4986791), Thr135Ala, TLR4_1859 G/A (rs11536858), TLR4_2032T/C (rs10116253), TLR4_2437A/G (rs1927914), TLR4_2856T/C (rs10759932), TLR4_3725 G/C (rs11536889), TLR4_7764 G/A (rs1927911), TLR4_11350G/C, TLR4_11912 G/T (rs2149356), TLR4_16649G/C (rs7873784), and TLR4_17050T/C (rs11536891).

Toll-like receptors as therapeutic targets in gastrointestinal diseases

IMPORTANCE OF THE FIELD

Toll-like receptors (TLRs) are innate immunity receptors that recognize several different antigens, initiating immunological/inflammatory responses. Recent evidence associates numerous pathophysiological processes and diseases with dysregulated activation of these receptors, conferring a potential therapeutic value to their modulation.

AREAS COVERED IN THIS REVIEW

The aim of this systematic review that covers literature from the past 10 years is to address the role of TLRs in the pathophysiology of gastrointestinal (GI) diseases as well as the therapeutic potential of modulating TLRs' signaling pathways in GI pathology.

WHAT THE READER WILL GAIN

This review shows that TLRs play an important role in the pathophysiology of several GI diseases and that modulating TLRs signaling pathways may have an enormous therapeutic potential. Different methods for modulation of TLRs' activity in GI tract, with direct agonists/antagonists but also with non-specific substances, like antibiotics or probiotics, are presented.

TAKE HOME MESSAGE

Even though TLRs modulators have been used for therapy in some GI diseases, further research, particularly in humans, is needed in order to establish the precise role of the different TLRs in the diverse GI diseases and to motivate clinical trials that consider TLRs as therapeutic targets in GI pathology.

Genetic association of Toll-like-receptor 4 and tumor necrosis factor-alpha polymorphisms with Plasmodium falciparum blood infection levels

Dysregulated innate immune responses due to inappropriate signaling by Toll-like receptors (TLRs) and aberrant production of pro-inflammatory cytokines are implicated in the immunopathology and disease outcome in Plasmodium falciparum malaria. This study investigates the relationship between polymorphic variability of candidate genes including TLR-2, -4, -9, tumor necrosis factor-alpha and lymphotoxin-alpha and blood infection level in Indian mild malaria patients. Genotyping was carried out by PCR-RFLP and sequencing. Association of parasite load with genotypes was examined using model based and model free approaches. Allele and haplotype based risk assessment for disease severity was performed by stratifying the patients into high and low parasitemic groups on the basis of a threshold value derived by employing a two-component mixture model and expectation-maximization algorithm. The mean parasitemia was significantly increased for variant homozygous genotype (C/C) at TNF-alpha promoter -1031 and major homozygous genotypes encoding Asp/Asp and Thr/Thr at codons 299 and 399, respectively, on TLR4 polypeptide. Individuals harboring combined genotype C/C-Asp/Asp-Thr/Thr on TNF-alpha and TLR4 presented the highest parasite load. The frequencies of variant allele C in TNF-1031 (OR=1.91 with 95% CI=1.24-2.94) and TNF-alpha promoter haplotypes C-C-G-G (OR=1.99 with 95% CI=1.21-3.27) and C-C-G-A (OR=2.96 with 95% CI=1.19-7.37) pertaining to loci TNF-1031/-857/-308/-238 were significantly elevated in the high parasitemic group. On the contrary, the frequencies of variant allele encoding Ile at 399 (OR=0.55 with 95% CI=0.32-0.94) and haplotype corresponding to Gly-Ile (299-399) (OR=0.51 with 95% CI=0.28-0.9) in TLR4 were higher in low parasitemic group. In silico analysis indicate differential binding of transcription factors to TNF-alpha promoter haplotypes and alteration in the surface charge distribution of the TLR4 variant proteins. Our results support a genetic role of TLR4 and TNF-alpha in controlling the blood infection level in mild malaria.