Association of polymorphisms in TNF-α, IL-1ß, GSTM and GSTT genes with apical periodontitis: is there a link with herpesviral infection?

AIM: To investigate the possible association between TNFα (-308 G/A) and IL-1ß (-511 C/T) single nucleotide polymorphisms (SNPs) and GSTT and GSTM deletion polymorphisms and risk of apical periodontitis (AP) development, and determine the association of different genotypes with the presence of herpesviral infection in AP. METHODOLOGY: The study included 120 periapical lesions and 200 control samples. Gene polymorphism analysis was performed using either polymerase chain reaction (PCR) or PCR/ restriction fragment length polymorphism (RFLP). Relative gene expression of TNF-α and IL-1ß was analysed using reverse transcriptase - real-time PCR. The presence of Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) was assessed by nested PCR. Chi-square and Fisher's exact tests and logistic regression analyses were done for polymorphisms, whilst Mann-Whitney U-test was performed for the expression analysis. The expected frequency of variants was analysed by the Hardy-Weinberg equilibrium test. RESULTS: TNF-α (-308 G/A) SNP increased AP susceptibility for heterozygous (odds ratio (OR) = 1.72, 95% confidence interval (CI) = 1.06-2.80, P = 0.027) and homozygous (OR = 8.55, 95% CI = 1.77-41.36, P < 0.001) carriers of the variant A allele. On the other hand, IL-1ß (-511 C/T) polymorphism exerted a protective effect both in heterozygotes (OR = 0.540, 95% CI = 0.332-0.880, P = 0.013) and homozygotes (OR = 0.114, 95% CI = 0.026-0.501, P < 0.001). In addition, GSTM1 and GSTT1 null genotypes separately, as well as concomitantly, were associated with an increased risk for AP development (P < 0.001). The null GSTT1 genotype increased approximately twice the risk of Epstein-Barr infection (EBV) in AP (OR = 2.17, 95% CI = 1-4.71, P = 0.048), whilst TNF-α SNP decreased it, both in heterozygotes (OR = 0.20, 95% CI = 0.08-0.48, P < 0.001) and AA homozygotes (OR = 0.07, 95% CI = 0.01-0.37, P = 0.001). CONCLUSIONS: GSTM and GSTT deletion polymorphisms, as well as TNFα (-308 G/A) SNP, are associated with increased risk, whereas IL-1ß (-511 C/T) polymorphism decreases the risk of AP development. GSTT and TNFα polymorphisms also appear to modulate the risk of EBV infection in Serbian patients with AP.

Genetic and epigenetic alterations in the tumour, tumour margins, and normal buccal mucosa of patients with oral cancer.

Despite adequate surgical resection, oral squamous cell carcinoma (OSCC) shows a high rate of recurrence and metastasis, which could be explained by the presence of molecular alterations in seemingly normal tumour margins and the entire oral mucosa. The aims of this study were (1) to assess the presence of gene amplification (c-Myc and HER2) and promoter methylation (p14 and p16) in the tumours, tumour margins, and unaffected oral mucosa of 40 OSCC patients, and (2) to evaluate the possibility of using these alterations as prognostic markers. c-Myc and HER2 genes were quantified by means of real-time PCR (qPCR), and p14 and p16 methylation status was determined by methylation-specific PCR (MSP PCR). All tissues examined exhibited molecular alterations in various proportions. Tumour tissues, as expected, showed the highest prevalence of alterations, while oral mucosa showed the lowest. Multiple alterations (co-alterations) in tumours and tumour margins were significantly more frequent than in unaffected oral mucosa (P<0.001 and P=0.027, respectively). HER2 amplification in margin tissue (P<0.001) and swabs (P=0.013), as well as the existence of three co-alterations in margins (P=0.001) and macroscopically unaffected oral mucosa (P<0.001) were correlated with shorter disease-specific survival.

Levels of oxidative stress biomarkers and bone resorption regulators in apical periodontitis lesions infected by Epstein-Barr virus.

AIM: To investigate whether apical periodontitis lesions infected by Epstein-Barr virus (EBV) exhibit higher levels of oxidative stress biomarkers [8-hydroxydeoxyguanosine (8-OHdG) and oxidized glutathione (GSSG)] and bone resorption regulators [receptor activator of nuclear factor (NF-κB) ligand (RANKL) and osteoprotegerin (OPG)] compared to EBV-negative periapical lesions and healthy pulp tissues. METHODOLOGY: The experimental group consisted of 30 EBV-positive and 30 EBV-negative periapical lesions collected in conjunction with apicoectomy. The pulp tissues of 20 impacted third molars were used as healthy controls. The qualitative and quantitative analysis of EBV was performed by nested and real-time polymerase chain reaction (PCR), respectively. The levels of RANKL and OPG were analysed by reverse transcriptase real-time PCR. The levels of 8-OHdG and GSSG were determined by enzyme-linked immunosorbent assay (ELISA). Mann-Whitney U-test and Spearman's correlation were used for statistical analysis. RESULTS: The levels of RANKL, OPG, 8-OHdG and GSSG were significantly higher in apical periodontitis lesions compared to healthy pulp controls (P = 0.001, P < 0.001, P < 0.001 and P < 0.05, respectively). RANKL and OPG mRNA expression was significantly higher in EBV-positive compared to EBV-negative periapical lesions (P < 0.05). There was no significant correlation between EBV copy numbers and levels of RANKL, OPG, 8OH-dG and GSSG in apical periodontitis. CONCLUSION: Levels of bone resorption regulators and oxidative stress biomarkers were increased in apical periodontitis compared to healthy pulp tissues. EBV-positive periapical lesions exhibited higher levels of RANKL and OPG compared to EBV-negative periapical lesions. EBV may contribute to progression of apical periodontitis via enhanced production of bone resorption regulators.

The amplification of c-erb-B2 in cancer-free surgical margins is a predictor of poor outcome in oral squamous cell carcinoma.

The tumour subtype, TNM classification, and histopathological data are sometimes not sufficient for understanding and assessing the behaviour of oral cancers. In an attempt to find additional markers of tumour biology and behaviour, this study sought to determine the incidence and consequently the relevance of c-erb-B2, c-Myc, and H-ras gene alterations in tumour-free margins of oral squamous cell carcinoma (OSCC). Fifty samples of OSCC were analyzed for c-erb-B2 and c-Myc amplification by real-time polymerase chain reaction and for H-ras point mutations by sequencing. A relatively high incidence of genetic lesions was detected: 22% of cases had c-erb-B2 and 30% had c-Myc amplification, whilst only 12% harboured H-ras mutations. Kaplan-Meier analysis and the log-rank test showed statistically significant differences in 5-year survival rates and relapse between patients with tumour margins positive for c-erb-B2 amplification and those with margins that were negative (P=0.002). H-ras and c-Myc alterations could not be associated with tumour behaviour. Molecular analysis of margins, targeting cancer genes, could identify additional, independent predictors of risk and outcome in OSCC.