Cecília Durães

Association Between Cytokine Gene Polymorphisms and Gastric Precancerous Lesions: Systematic Review and Meta-analysis

Polymorphisms within interleukin-1 (IL1) and tumor necrosis factor α (TNFA) gene clusters are associated with an increased risk of gastric cancer. However, their role in gastric precancerous lesions remains poorly understood. Our objective was to perform a meta-analysis of studies addressing the association between IL1B-511, IL1RN variable number of tandem repeat, and TNFA-308 gene polymorphisms and gastric precancerous lesions, including original data from Portugal and Mozambique. Published studies on the association between these cytokine gene polymorphisms and gastric precancerous lesions were identified by systematic review, and estimates of the association were combined using random-effects meta-analysis taking into account new data obtained from Portuguese volunteer shipyard workers (n = 215) and Mozambican dyspeptic patients (n = 96) who underwent endoscopic and pathologic evaluation following the same protocol. Odds ratio (OR) estimates for intestinal metaplasia were 2.83 [95% confidence interval (95% CI), 1.15-6.96] for the IL1RN*22 genotype, 1.86 (95% CI, 1.03-3.36) for IL1B-511 T carriers, and 0.59 (95% CI, 0.12-3.04) for the TNFA-308*AA genotype in the Portuguese sample. All Mozambican subjects with intestinal metaplasia were T carriers for IL1B-511 and none had the 2 allele for IL1RN. In meta-analysis, IL1RN*22 genotype was associated with an increased risk of gastric precancerous lesions (22 versus LL: OR, 2.27; 95% CI, 1.40-3.70; I2 = 26.4%; 12 studies). No such association was found for the IL1B-511 (TT versus CC: OR, 1.34; 95% CI, 0.87-2.07; I2 = 65.7%; 13 studies) or TNFA-308 genotypes (AA versus GG: OR, 0.93; 95% CI, 0.35-2.43; I2 = 0.0%; 7 studies). The IL1RN*22 genotype seems to consistently increase the risk of gastric precancerous lesions, supporting a role for this polymorphism in the early stages of gastric carcinogenesis. Cancer Epidemiol Biomarkers Prev; 19(3); 762–76

A polymorphism in the promoter region of the selenoprotein S gene (SEPS1) contributes to Hashimoto's thyroiditis susceptibility.

CONTEXT The association between selenium and inflammation and the relevance of selenoproteins in follicular thyroid cell physiology have pointed to a putative role of selenoproteins in the pathogenesis of autoimmune thyroid diseases. OBJECTIVE The aim of this study was to evaluate the role of a promoter variation in SEPS1, the selenoprotein S gene, in the risk for developing Hashimotos thyroiditis (HT). DESIGN A case-control study was performed to assess the association of genetic variation in the SEPS1 gene (SEPS1 -105G/A single-nucleotide polymorphism, rs28665122) and HT. SETTING The study was conducted in north Portugal, Porto, in the period of 2007-2013. PATIENTS OR OTHER PARTICIPANTS A total of 997 individuals comprising 481 HT patients and 516 unrelated controls were enrolled in the study. MAIN OUTCOME MEASURES Genetic variants were discriminated by real-time PCR using TaqMan single-nucleotide polymorphism genotyping assays. RESULTS There is a significant association between the SEPS1 -105 GA and AA genotypes and HT [odds ratio (OR) 2.24, confidence interval (CI) 1.67-3.02, P < 5.0 × 10(-7), and OR 2.08, CI 1.09-3.97, P = .0268, respectively]. The A allele carriers are in higher proportion in the patient group than in the control population (46.2% vs 28.1%, P < 5.0 × 10(-7)) with an OR (CI) of 2.22 (1.67-2.97). The proportion of patients carrying the A allele is significantly higher in male patients with HT, representing a 3.94 times increased risk (P = 7.9 × 10(-3)). CONCLUSION Our findings support the existence of a link between SEPS1 promoter genetic variation and HT risk.

Phenotype–genotype profiles in Crohn's disease predicted by genetic markers in autophagy‐related genes (GOIA study II)

Background:About 70 loci are associated with susceptibility to Crohns disease (CD), particularly in pathways of innate immunity, autophagy, and pathogen recognition. Phenotype–genotype associations are inconsistent. Methods:CD susceptibility polymorphisms ATG16L1 rs2241880, ICAM1 rs5498, IL4 rs2070874, IL17F rs763780, IRGM rs13361189, ITLN1 rs2274910, LRRK2 rs11175593, and TLR4 rs4986790 were genotyped in a Portuguese population (511 CD patients, 626 controls) and assessed for association with CD clinical characteristics. Results:There is a significant association of CD with the single nucleotide polymorphisms (SNPs) in ATG16L1 (odds ratio [OR] 1.36 [1.15–1.60], P = 2.7 × 10−4 for allele G), IRGM (OR 1.56 [1.21–1.93], P = 3.9 × 10−4 for allele C), and ITLN1 (OR 1.55 [1.28–1.88], P = 4.9 × 10−6 for allele C). These SNPs are associated with ileal location (OR, respectively, 1.49, 1.52, and 1.70), ileocolonic location (OR, respectively, 1.31, 1.57, and 1.68), and involvement of the upper digestive tract (OR, respectively for ATG16L1 and IRGM, 1.96 and 1.95). The risk genotype GG in ATG16L1 is associated with patients who respond to steroids (OR 1.89), respond to immunosuppressants (OR 1.77), and to biologic therapy (OR 1.89). The SNPs in ITLN1 and IRGM are both associated with a positive response to biologic therapy. The risk for ileal, ileocolonic, and upper digestive tract locations increases with the number of risk alleles (OR for three alleles, respectively, 7.10, 3.54, and 12.07); the OR for positive response to biologic therapy is 3.66. Conclusions:A multilocus approach using autophagy-related genes provides insight into CD phenotype–genotype associations and genetic markers for predicting therapeutic responses.

Tumor Necrosis Factor Alpha Extended Haplotypes and Risk of Gastric Carcinoma

The tumor necrosis factor α (TNFA)-308*A allele has been found to confer an increased risk of gastric carcinoma. Inconsistency in risk estimates across populations lead us to hypothesize about the presence of an alternative causal locus in the same chromosomal region. A suitable approach is to determine the tumor necrosis factor haplotypic structure in order to clarify whether the association between the *A allele and the increased risk of gastric carcinoma is etiologic or secondary to linkage disequilibrium. Firstly, we assessed the association between the TNFA-308G>A polymorphism and the risk of gastric carcinoma in a population from Northern Portugal (508 gastric carcinoma patients, 713 controls); secondly, we genotyped five microsatellite loci (TNFa, b, c, d, e) flanking the TNFA-308G>A locus to establish the haplotypic structure associated with this single-nucleotide polymorphism in cases (122 patients) and controls (169 individuals). We found a significant association between the *A allele and increased risk of gastric carcinoma (odds ratio, 1.7; 95% confidence interval, 1.3-2.2) confirming previous results in our population. Regarding the *A allele–associated haplotypes, the most relevant difference was found for the H1A haplotype present in 33.1% of the cases and 12.5% of the controls. We also observed haplotypes associated with the *A allele that were found only in cases or controls. A population differentiation test showed that the gastric carcinoma and the control groups were significantly different for the *A allele haplotypic structure. This suggests that the association between the TNFA-308G>A polymorphism and increased risk of gastric carcinoma is dependent on linkage disequilibrium with an as yet unidentified locus. (Cancer Epidemiol Biomarkers Prev 2008;17(9):2416–20)

Quantification of mutant E-cadherin using bioimaging analysis of in situ fluorescence microscopy. A new approach to CDH1 missense variants

Missense mutations result in full-length proteins containing an amino acid substitution that can be neutral or deleterious, interfering with the normal conformation, localization, and function of a protein. A striking example is the presence of CDH1 (E-cadherin gene) germline missense variants in hereditary diffuse gastric cancer (HDGC), which represent a clinical burden for genetic counseling and surveillance of mutation carriers and their families. CDH1 missense variants can compromise not only the function of E-cadherin but also its expression pattern. Here, we propose a novel method to characterize E-cadherin signature in order to identify cases with E-cadherin deregulation and functional impairment. The strategy includes a bioimaging pipeline to quantify the expression level and characterize the distribution of the protein from in situ immunofluorescence images. The algorithm computes 1D (dimension intensity) radial and internuclear fluorescence profiles to generate expression outlines and 2D virtual cells representing a typical cell within the populations analyzed. Using this new approach, we verify that cells expressing mutant forms of E-cadherin display fluorescence profiles distinct from those of the wild-type cells. Mutant proteins showed a significantly decrease of fluorescence intensity at the membrane and often abnormal expression peaks in the cytoplasm, reflecting the underlying molecular mechanism of trafficking deregulation. Our results suggest employing this methodology as a complementary approach to evaluate the pathogenicity of E-cadherin missense variants. Moreover, it can be applied to a wide range of proteins and, more importantly, to diseases characterized by aberrant protein expression or trafficking deregulation.

C/EBPα expression is associated with homeostasis of the gastric epithelium and with gastric carcinogenesis

Transcription factors from the CCAAT/enhancer-binding protein (C/EBP) family are fundamental for the control of differentiation and proliferation of many adult tissues. C/EBPα has a crucial role in inducing terminal differentiation and is an established tumor suppressor gene in several cancer models. The objective of this study was to analyze the putative role of C/EBPα in gastric carcinoma (GC). We analyzed the expression of C/EBPα in normal and neoplastic gastric tissues, and assessed the role of C/EBPα on proliferation and differentiation of GC cells. In normal gastric mucosa, C/EBPα is expressed in the foveolar epithelium and co-localizes with the gastric differentiation marker trefoil factor 1 (TFF1). The expression of C/EBPα was found to be lost in 30% of GC cases. To evaluate the role of C/EBPα in cell proliferation and differentiation, we transfected GC cells with a full-length C/EBPα protein. We observed a significant decrease in proliferation in C/EBPα-transfected cells. This was accompanied by a decrease in Cyclin D1, an increase in P27 expression, and an increased expression of TFF1. Finally, we showed that inhibition of the Ras/MAPK pathway leads to increased C/EBPα and TFF1 expression, and decreased cell proliferation and cyclin D1 expression in GC cells. Our results suggest that C/EBPα (together with other members of the C/EBP family) has an active role in the control of differentiation and proliferation in normal gastric mucosa. In GC, loss of C/EBPα may be associated with the switch from a cellular differentiation to a cellular proliferation program, presumably as a consequence of Ras/MAPK pathway activation.

Genetic variants in the IL1A gene region contribute to intestinal-type gastric carcinoma susceptibility in European populations

The most studied genetic susceptibility factors involved in gastric carcinoma (GC) risk are polymorphisms in the inflammation‐linked genes interleukin 1 (IL1) B and IL1RN. Despite the evidence pointing to the IL1 region, definite functional variants reproducible across populations of different genetic background have not been discovered so far. A high density linkage disequilibrium (LD) map of the IL1 gene cluster was established using HapMap to identify haplotype tagSNPs. Eighty‐seven SNPs were genotyped in a Portuguese case‐control study (358 cases, 1,485 controls) for the discovery analysis. A replication study, including a subset of those tagSNPs (43), was performed in an independent analysis (EPIC‐EurGast) containing individuals from 10 European countries (365 cases, 1284 controls). Single SNP and haplotype block associations were determined for GC overall and anatomopathological subtypes. The most robust association was observed for SNP rs17042407, 16Kb upstream of the IL1A gene. Although several other SNP associations were observed, only the inverse association of rs17042407 allele C with GC of the intestinal type was observed in both studies, retaining significance after multiple testing correction (p = 0.0042) in the combined analysis. The haplotype analysis of the IL1A LD block in the combined dataset revealed the association between a common haplotype carrying the rs17042407 variant and GC, particularly of the intestinal type (p = 3.1 × 10−5) and non cardia localisation (p = 4.6 × 10−3). These results confirm the association of IL1 gene variants with GC and reveal a novel SNP and haplotypes in the IL1A region associated with intestinal type GC in European populations.

Association between Polymorphisms in Antioxidant Genes and Inflammatory Bowel Disease

Inflammation is the driving force in inflammatory bowel disease (IBD) and its link to oxidative stress and carcinogenesis has long been accepted. The antioxidant system of the intestinal mucosa in IBD is compromised resulting in increased oxidative injury. This defective antioxidant system may be the result of genetic variants in antioxidant genes, which can represent susceptibility factors for IBD, namely Crohn’s disease (CD) and ulcerative colitis (UC). Single nucleotide polymorphisms (SNPs) in the antioxidant genes SOD2 (rs4880) and GPX1 (rs1050450) were genotyped in a Portuguese population comprising 436 Crohn’s disease and 367 ulcerative colitis patients, and 434 healthy controls. We found that the AA genotype in GPX1 is associated with ulcerative colitis (OR = 1.93, adjusted P-value = 0.037). Moreover, we found nominal significant associations between SOD2 and Crohn’s disease susceptibility and disease subphenotypes but these did not withstand the correction for multiple testing. These findings indicate a possible link between disease phenotypes and antioxidant genes. These results suggest a potential role for antioxidant genes in IBD pathogenesis and should be considered in future association studies.

Common vascular endothelial growth factor variants and risk for posttransplant Kaposi sarcoma.

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IL6-174 G>C Polymorphism (rs1800795) Association with Late Effects of Low Dose Radiation Exposure in the Portuguese Tinea Capitis Cohort.

Head and neck cancers, and cardiovascular disease have been described as late effects of low dose radiation (LDR) exposure, namely in tinea capitis cohorts. In addition to radiation dose, gender and younger age at exposure, the genetic background might be involved in the susceptibility to LDR late effects. The -174 G>C (rs1800795) SNP in IL6 has been associated with cancer and cardiovascular disease, nevertheless this association is still controversial. We assessed the association of the IL6-174 G>C SNP with LDR effects such as thyroid carcinoma, basal cell carcinoma and carotid atherosclerosis in the Portuguese tinea capitis cohort. The IL6-174 G>C SNP was genotyped in 1269 individuals formerly irradiated for tinea capitis. This sampling group included thyroid cancer (n = 36), basal cell carcinoma (n = 113) and cases without thyroid or basal cell carcinoma (1120). A subgroup was assessed for atherosclerosis by ultrasonography (n = 379) and included matched controls (n = 222). Genotypes were discriminated by real-time PCR using a TaqMan SNP genotyping assay. In the irradiated group, we observed that the CC genotype was significantly associated with carotid plaque risk, both in the genotypic (OR = 3.57, CI = 1.60–7.95, p-value = 0.002) and in the recessive (OR = 3.02, CI = 1.42–6.42, p-value = 0.004) models. Irradiation alone was not a risk factor for carotid atherosclerosis. We did not find a significant association of the IL6-174 C allele with thyroid carcinoma or basal cell carcinoma risk. The IL6-174 CC genotype confers a three-fold risk for carotid atherosclerotic disease suggesting it may represent a genetic susceptibility factor in the LDR context.