Association between TNF-α, Interleukin-18 Polymorphisms and Risk of Hepatocellular Carcinoma in Egyptian patients

Interleukin-18 in metabolism: From mice physiology to human diseases

Interleukin-18 (IL-18) is a classical member of the IL-1 superfamily of cytokines. As IL-1β, IL-18 precursor is processed by inflammasome/caspase-1 into a mature and biologically active form. IL-18 binds to its specific receptor composed of two chains (IL-18Rα and IL-18Rβ) to trigger a similar intracellular signaling pathway as IL-1, ultimately leading to activation of NF-κB and inflammatory processes. Independently of this IL-1-like signaling, IL-18 also specifically induces IFN-γ production, driving the Th1 immune response. In circulation, IL-18 binds to the IL-18 binding protein (IL-18BP) with high affinity, letting only a small fraction of free IL-18 able to trigger receptor-mediated signaling. In contrast to other IL-1 family members, IL-18 is produced constitutively by different cell types, suggesting implications in normal physiology. If the roles of IL-18 in inflammatory processes and infectious diseases are well described, recent experimental studies in mice have highlighted the action of IL-18 signaling in the control of energy homeostasis, pancreatic islet immunity and liver integrity during nutritional stress. At the same time, clinical observations implicate IL-18 in various metabolic diseases including obesity, type 1 and 2 diabetes and nonalcoholic fatty liver disease (NAFLD)/nonalcoholic steatohepatitis (NASH). In the present review, we summarize and discuss both the physiological actions of IL-18 in metabolism and its potential roles in pathophysiological mechanisms leading to the most common human metabolic disorders, such as obesity, diabetes and NAFLD/NASH.

Evaluation of genetic and epigenetic changes of Tumor Necrosis Factor-Alpha gene in larynx cancer

BACKGROUND

Tumor Necrosis Factor-Alpha (TNF-α) is a proinflammatory cytokine that plays a role in inflammation, which is one of the hallmarks of cancer, and its polymorphic variants have been associated with disease risk in many cancers in the literature. The aim of this study was to investigate four different polymorphic variants, differential methylation and expression status of the TNF-α gene and to determine the associations between these variants and disease risk, and to evaluate the relationship between the results and clinical parameters. We purposed to investigate the genetic and epigenetic alterations of the TNF-α gene in larynx cancer (LC).

MATERIAL AND METHODS

After isolation of DNA/RNA from whole blood, tumor and normal tissue, polymorphic variant alleles differrential expression and methylation levels were analyzed by RFLP, semiquantitative RT-PCR, and restriction enzyme digestion, respectively. TNF-α expression and methylation levels were calculated using BIO1D software. The frequencies of the variants c.-238 G>A (rs361525), c.-857 C>T (rs1799724), c.-863 C>A (rs1800630), and c.-1031 T > C (rs1799964) in the promoter region of TNF-α in LC Turkish patients and healthy individuals were examined using the De-Finetti case-control program. Haplotype frequencies and linkage disequilibrium were analyzed using the SNPStats program.

RESULTS

The frequency of genotype c.-1031 T > C was significantly lower in patients than in healthy individuals [TT vs TC: OR (%95CI) = 7.00 (1.75-27.93), p = 0.003, χ2 = 8.76]. The heterozygous variant of - 857 was associated with recurrence [T vs G: OR (%95CI) = 0.15 (0.02-0.95), p = 0.02, χ2 = 4.86]. For c.-238 G>A, c.-857 C>T, and c.-863 C>A, there was no statistically significant difference between the patient and healthy group in terms of disease risk. A significant association was found between c.-1031 T > C and disease risk of LC. Decreased expression was detected in 46% (23/50) and increased expression in 54% (27/50) of tumor tissue samples compared to the matched normal tissues of patients. Methylation-related loss of expression was detected in 53.3% (16/30) of patients.

CONCLUSION

Our study is the first investigating four different polymorphic regions of the TNF-α promoter region and the expression/methylation status of TNF-α in the same LC patient and healthy cohort. According to our results, the c.-1031 T > C variant was reported to be significantly associated with a reduced risk of LC. In addition, the TNF-α variant c. -857 C>T suggests that it may be a potential biomarker for predicting the recurrence of LC. An association between c. -857 C>T variant and methylation-based expression status was observed.

Inflammasome-Mediated Cytokines: A Key Connection between Obesity-Associated NASH and Liver Cancer Progression

Liver cancer is one of the most lethal malignancies and is commonly diagnosed as hepatocellular carcinoma (HCC), a tumor type that affects about 90% of patients. Non-alcoholic steatohepatitis (NASH) and obesity are both risk factors for this disease. HCC initiation and progression are deeply linked with changes in the hepatic microenvironment, with cytokines playing key roles. The understanding of the pathogenic pathways that connect these disorders to liver cancer remains poor. However, the inflammasome-mediated cytokines associated with both diseases are central actors in liver cancer progression. The release of the pro-inflammatory cytokines IL-1β and IL-18 during inflammasome activation leads to several detrimental effects on the liver microenvironment. Considering the critical crosstalk between obesity, NASH, and HCC, this review will present the connections of IL-1β and IL-18 from obesity-associated NASH with HCC and will discuss approaches to using these cytokines as therapeutic targets against HCC.