Haplotypes of the IL-1 gene cluster are associated with gastroesophageal reflux disease and Barrett’s esophagus

Functional genetic variations of CYP2C19 promoter from patients with gastroesophageal reflux disease

BACKGROUND

Gastroesophageal reflux disease (GERD) is a chronic, progressive condition, and its prevalence is increasing worldwide. The risk factors for GERD are complex and the pathogenesis of GERD has not been fully elucidated. As acid-suppressive drugs, proton pump inhibitors (PPIs) are commonly used to treat GERD; after being metabolized by CYP2C19 in the human liver, the blood concentration of PPIs gradually decreases. Previous studies have shown that CYP2C19 gene polymorphism leads to considerable individual differences of PPIs in terms of metabolic rate and efficacy.

AIM

To identify potential variations in CYP2C19 promoter from patients (normal metabolizers, NMs, *1/*1) with GERD, verify the activity of promoter with variations in HEK 293T, and analyze the correlation between variations in CYP2C19 promoter and PPI treatment effect for GERD in the Chinese population.

METHODS

A total of 163 patients with sporadic GERD were collected. After diagnostic treatment with PPIs, the symptom score decreased by 50%, but the symptoms did not completely disappear in the study group (n = 82). In the control group (n = 81), the symptoms completely disappeared after treatment. The CYP2C19 genotype of all patients was detected as *1/*1. The PCR and Sanger sequencing were used to identify variations in the CYP2C19 promoter. The luciferase activities of pGL3 basic-CYP2C19 promoters with or without variation were detected by dual-luciferase assay.

RESULTS

Three novel heterozygous variations were identified in the CYP2C19 gene promoters isolated from three NM patients with GERD: g.94761364 T>A, g.94762112 T>A, and g.94762514 G>T. Compared to the wild type, the transcriptional activity of the CYP2C19 promoter with g.94761364 T>A was significantly increased (P = 0.034).

CONCLUSION

The transcriptional activity of the CYP2C19 promoter is significantly increased in the presence of g.94761364 T>A, which may further affect the metabolism and blood concentration of PPIs. This finding provides a new insight for the medication and treatment of GERD patients in the Chinese population.

Interleukin-1A and interleukin-1B gene polymorphisms in gastroesophageal reflux disease

Inflammation may play contradictory roles in the pathogenesis of gastroesophageal reflux disease (GERD): gastritis decreases gastric output and reduces the risk of esophagitis, while interleukins may favor mucosal inflammation. The inflammation may cause esogastric motility changes and thus increase the risk of esophagitis. Considering the genetic influence of inflammatory response, we looked for the genetic polymorphisms of IL-1 in GERD manifested as reflux esophagitis. This is a prospective study carried out in GERD and healthy controls. We assessed in these groups the following single nucleotide polymorphisms (SNPs): IL-1A (rs1800587), IL-1B (rs16944), IL-1B (rs1143634) and the VNTR for IL-1RN. Both groups were similar according to biographical data. Reflux esophagitis was confirmed by endoscopy and where necessary by pH-impedance monitoring. Reflux esophagitis was associated only with the polymorphism rs16944. No other correlations with the other three genetic polymorphisms were detected. These data suggest that the diverging effects of proinflammatory factors on the upper digestive tract may have deleterious effect on GERD. The IL-1B (rs16944) SNP correlates with reflux esophagitis.

Interleukin Gene Variability and Periodontal Bacteria in Patients with Generalized Aggressive Form of Periodontitis

Host genetic predispositions to dysregulated immune response can influence the development of the aggressive form of periodontitis (AgP) through susceptibility to oral dysbiosis and subsequent host-microbe interaction. This case-control study aimed to perform a multilocus analysis of functional variants in selected interleukin (IL) genes in patients with the generalized form of AgP in a homogenous population. Twelve polymorphisms in IL-1 gene cluster, IL-6 and its receptor, IL-10, IL-17A, and IL-18 were determined in 91 AgP patients and 210 controls. Analysis of seven selected periodontal bacteria in subgingival sulci/pockets was performed with a commercial DNA-microarray kit in a subgroup of 76 individuals. The pilot in vitro study included stimulation of peripheral blood monocytes (PBMC) from 20 individuals with periodontal bacteria and measurement of IL-10 levels using the Luminex method. Only the unctional polymorphism IL-10 −1087 A/G (rs1800896) and specific IL-10 haplotypes were associated with the development of the disease (p < 0.05, P_corr > 0.05). Four bacterial species occurred more frequently in AgP than in controls (p < 0.01, P_corr < 0.05). Elevated IL-10 levels were found in AgP patients, carriers of IL-10 −1087GG genotype, and PBMCs stimulated by periodontal bacteria (p < 0.05, P_corr > 0.05). We therefore conclude that a combination of genetic predisposition to the altered expression of IL-10 and the presence of specific periodontal bacteria may contribute to Th1/Th2 balance disruption and AgP development.

Gene-Environment Interactions and the Risk of Barrett's Esophagus in Three US Cohorts

OBJECTIVES

Several single-nucleotide polymorphisms (SNPs) have been associated with Barrett's esophagus (BE) risk. In addition, environmental factors including smoking, alcohol consumption, and heartburn increase BE risk. However, data on potential interactions between these genetic and environmental factors on BE risk are scant. Understanding how genes and environmental risk factors interact may provide key insight into the pathophysiology of BE, and potentially identify opportunities for targeted prevention and treatment. The objectives of this study were to examine the main effects and the potential effect modification between known genetic loci (SNPs) and established environmental risk factors for BE.

METHODS

We performed a nested case-control study using data on 401 incident BE cases and 436 age-matched controls from the Nurses' Health Study, Nurses' Health Study II, and Health Professionals Follow-up Study cohorts, who gave blood and completed biennial questionnaires. Overall, we genotyped 46 SNPs identified in previous BE genome-wide association studies as well as SNPs in candidate genes related to BE susceptibility (i.e., related to excess body fat, fat distribution, factors associated with insulin resistance, and inflammatory mediators). A genetic risk score (GRS) was constructed to evaluate the combined effect of the selected SNPs on BE risk. Interactions between SNPs and BE risk factors were also assessed.

RESULTS

We observed a suggestive, but not statistically significant, association between our GRS and BE risk: a one-allele increase in the unweighted GRS increased the risk of BE by a factor of 1.20 (95% confidence interval = 1.00-1.44; P = 0.057). We did not observe any meaningful multiplicative interactions between smoking, alcohol consumption, or heartburn duration and BE genotypes. When we assessed the joint effect of weighted GRS and BE risk factors, we did not observe any significant interaction with alcohol and heartburn duration, whereas smoking showed a significant multiplicative interaction (P = 0.016).

CONCLUSIONS

Our results suggest that SNPs associated with BE at genome-wide significant levels can be combined into a GRS with a potential positive association with BE risk.

Interleukin-1 Gene Variability and Plasma Levels in Czech Patients with Chronic Periodontitis and Diabetes Mellitus

Recent studies have suggested a bidirectional relationship between chronic periodontitis (CP) and diabetes mellitus (DM). Immunoregulatory factors such as cytokines play an important role in etiopathogenesis of both diseases. The aim of this study was to analyze variability in interleukin-1 (IL-1) gene cluster and IL-1β plasma levels in patients with CP, DM, and a combination of both diseases. A total of 1016 individuals participating in this case-control study—225 healthy controls, 264 patients with CP, 132 with type 1 diabetes (T1DM), and 395 patients with type 2 diabetes (T2DM)—were genotyped using methods based on polymerase chain reaction for IL-1 gene polymorphisms (IL-1A (−889C/T, rs1800587), IL-1B (+3953C/T, rs1143634), and IL-1RN (gene for IL-1 receptor antagonist, IL-1RA, 86 bp tandem repeats in intron 2)). Levels of IL-1β were measured by Luminex methods in subgroups of controls, CP, T1DM + CP, and T2DM + CP subjects. Although no significant associations were found in the genotype and allele frequencies of IL-1A (−889C/T), significant differences in the allele frequencies of IL-1B (+3953C/T) were observed between controls and CP patients (P < 0.05). In T1DM patients, IL-1RN^∗S “short” allele and IL-1RN 12 genotype were significantly less frequent than those in controls (P < 0.01). In haplotype analysis, TTL haplotype decreased the risk of CP development (P < 0.01), whereas CCS and CTL haplotypes (P < 0.01 and P < 0.05) were associated with T1DM. Although IL-1β levels were measured significantly higher in mononuclear cells after stimulation by mitogens, HSP70, or selected periodontal bacteria than in unstimulated cells, IL-1 genotypes did not correlate with circulating IL-1β levels. In the Czech population, significant associations between the IL-1B polymorphism with CP and the IL-1RN variant with T1DM were found. Haplotype analysis suggests that variability in IL-1 gene cluster may be one of the factors in the CP and T1DM pathogenesis, although single variants of these polymorphisms are not substantial for protein production.

Association study of interleukin-1 family, interleukin-6, and its receptor gene polymorphisms in patients with recurrent aphthous stomatitis

BACKGROUND

Recurrent aphthous stomatitis (RAS) is one of the most common oral chronic ulcerative disease in which proinflammatory cytokines such as interleukin-1 (IL-1) and interleukin-6 (IL-6) are thought to play an important role. The aim of this study was to investigate the possible association between polymorphisms in the IL-1 cytokine family, IL-6 or its receptor and RAS in the Czech population.

METHODS

A total of 248 subjects, 184 healthy controls, and 64 patients with RAS were genotyped for IL-1A-889C>T, IL-1B-511C>T, IL-1B+3953C>T, IL-1RN86 bp variable number of tandem repeats (VNTRs) in intron 2, IL-6-597G>A, IL-6-572G>C, IL-6-174G>C, and IL-6R+48992A>C by polymerase chain reaction (PCR) methods.

RESULTS

No significant differences between investigated polymorphisms in healthy subjects and patients with RAS were detected (P>.05). In addition, complex analysis also revealed similar IL-1 or IL-6 haplotype frequencies between both groups (P>.05).

CONCLUSIONS

In conclusion, IL-1 and IL-6 or its receptor gene variants cannot be used as markers for identification of Czech patients with increased risk of recurrent aphthous stomatitis.

Common Variants Confer Susceptibility to Barrett's Esophagus: Insights from the First Genome-Wide Association Studies

Eight loci have been identified by the two genome-wide association studies of Barrett's esophagus that have been conducted to date. Esophageal adenocarcinoma cases were included in the second study following evidence that predisposing genetic variants for this cancer overlap with those for Barrett's esophagus. Genes with roles in embryonic development of the foregut are adjacent to 6 of the loci identified (FOXF1, BARX1, FOXP1, GDF7, TBX5, and ALDH1A2). An additional locus maps to a gene with known oncogenic potential (CREB-regulated transcription coactivator 1), but expression quantitative trait data implicates yet another gene involved in esophageal development (PBX4). These results strongly support a model whereby dysregulation of genes involved in esophageal and thoracic development increases susceptibility to Barrett's esophagus and esophageal adenocarcinoma, probably by reducing anatomical antireflux mechanisms. An additional signal at 6p21 in the major histocompatibility complex also reinforces evidence that immune and inflammatory response to reflux is involved in the development of both diseases. All of the variants identified are intronic or intergenic rather than coding and are presumed to be or to mark regulatory variants. As with genome-wide association studies of other diseases, the functional variants at each locus are yet to be identified and the genes affected need confirming. In this chapter as well as discussing the biology behind each genome-wide association signal, we review the requirements for successfully conducting genome-wide association studies and discuss how progress in understanding the genetic variants that contribute to Barrett's esophagus/esophageal adenocarcinoma susceptibility compares to other cancers.

The Genetics of Barrett's Esophagus: A Familial and Population-Based Perspective

Barrett's esophagus (BE) is intestinal metaplasia of the lower esophagus and a precursor lesion for esophageal adenocarcinoma (EAC). Both are important health issues as they have rising incidences in the Western world. Improving the management of BE relies on understanding the underlying biology of this disease, but the exact biological mechanisms have been difficult to determine. BE is generally thought to be an acquired condition that develops secondarily to chronic gastroesophageal reflux. However, multiple reports of familial clustering of patients with BE and/or EAC suggest a possible inherited predisposition to BE may be driving this condition, at least in a subset of patients. Identifying the genetic variants that predispose to BE in these families would open up the possibility for blood-based screening tests that could inform decision-making in regard to surveillance strategies, particularly for relatives of patients with BE and/or EAC. Perhaps more importantly, understanding the genetic mechanisms that predispose to BE may provide valuable insights into the biology of this condition and potentially identify novel targets for therapeutic intervention. Here we review the current evidence for a genetic predisposition to BE and discuss the potential implications of these findings.

Genetic Biomarkers of Barrett's Esophagus Susceptibility and Progression to Dysplasia and Cancer: A Systematic Review and Meta-Analysis

Barrett's esophagus (BE) is a common and important precursor lesion of esophageal adenocarcinoma (EAC). A third of patients with BE are asymptomatic, and our ability to predict the risk of progression of metaplasia to dysplasia and EAC (and therefore guide management) is limited. There is an urgent need for clinically useful biomarkers of susceptibility to both BE and risk of subsequent progression. This study aims to systematically identify, review, and meta-analyze genetic biomarkers reported to predict both. A systematic review of the PubMed and EMBASE databases was performed in May 2014. Study and evidence quality were appraised using the revised American Society of Clinical Oncology guidelines, and modified Recommendations for Tumor Marker Scores. Meta-analysis was performed for all markers assessed by more than one study. A total of 251 full-text articles were reviewed; 52 were included. A total of 33 germline markers of susceptibility were identified (level of evidence II-III); 17 were included. Five somatic markers of progression were identified; meta-analysis demonstrated significant associations for chromosomal instability (level of evidence II). One somatic marker of progression/relapse following photodynamic therapy was identified. However, a number of failings of methodology and reporting were identified. This is the first systematic review and meta-analysis to evaluate genetic biomarkers of BE susceptibility and risk of progression. While a number of limitations of study quality temper the utility of those markers identified, some-in particular, those identified by genome-wide association studies, and chromosomal instability for progression-appear plausible, although robust validation is required.

IL-1RT1 signaling antagonizes IL-11 induced STAT3 dependent cardiac and antral stomach tumor development through myeloid cell enrichment

IL-1 is key driver of gastric tumorigenesis and is a downstream target of IL-11 signaling. Recently, IL-1 cytokines, particularly IL-1β, have been flagged as therapeutic targets for gastric cancer treatment. Here, we assess the requirement for IL-1 signaling in gastric tumorigenesis. gp130757FF xIL-1RT1-/- mice were generated to determine the pathological consequence of ablated IL-1 signaling in the IL-11 dependent gp130757FF mouse model of gastric tumorigenesis. Gastric lesions in gp130757FF xIL-1RT1-/- mice were increased in incidence and size compared to gp130757FF mice. Proximal gastric lesions originated from the cardiac region and were associated with elevated STAT3 activation, loss of specialized gastric cells and a modulated immune response including increased expression of TNF-α and MDSC associated genes. Administration of IL-11 to IL-1RT1-/- mice showed similar changes to gp130757FF xIL-1RT1-/- mice. Spleens from IL-11 treated wildtype mice showed an enrichment of MDSC and gp130757FF xIL-1RT1-/- mice had increased MDSCs in the stomach compared to gp130757FF mice. Furthermore, crossing TNF-α-/- to gp130757FF mice resulted in reduced lesion size. We conclude that IL-1 signaling antagonizes IL-11/STAT3 mediated pathology and the genetic deletion of IL-1RT1 results in increased tumor burden. We provide evidence that a likely mechanism is due to IL-11/STAT3 dependent enrichment of MDSCs.

Genetic susceptibility to Barrett's oesophagus: Lessons from early studies

Barrett’s oesophagus (BO) is a common condition, predisposing strongly to the development of oesophageal adenocarcinoma (OAC). Consequently, there has been considerable effort to determine the processes involved in the development of BO metaplasia, and ultimately develop markers of patients at risk. Whilst a number of robust acquired risk factors have been identified, a genetic component to these and the apparent increased susceptibility of certain individuals has long been suspected. This has been evidenced in part by linkage studies, but subsequently two recent genome-wide association studies (GWAS) have suggested mechanisms underlying the heritability of BO, as well as providing the first direct evidence at modern levels of statistical significance. This review discusses BO heritability, in addition to that of individual variants and genes reported to be associated with BO to date. Through this, we identify a number of plausible associations, although often tempered by issues of methodology, and discuss the priorities and need for future research.