[Methylation of Regulatory Regions of DNA Repair Genes in Carotid Atherosclerosis].

The status of DNA methylation in the human genome changes during the pathogenesis of common diseases and acts as a predictor of life expectancy. Therefore, it is of interest to investigate the methylation level of regulatory regions of genes responsible for general biological processes that are potentially significant for the development of age-associated diseases. Among them there are genes encoding proteins of DNA repair system, which are characterized by pleiotropic effects. Here, results of the targeted methylation analysis of two regions of the human genome (the promoter of the MLH1 gene and the enhancer near the ATM gene) in different tissues of patients with carotid atherosclerosis are present. Analysis of the methylation profiles of studied genes in various tissues of the same individuals demonstrated marked differences between leukocytes and tissues of the vascular wall. Differences in methylation levels between normal and atherosclerotic tissues of the carotid arteries were revealed only for two studied CpG sites (chr11:108089866 and chr11:108090020, GRCh37/hg19 assembly) in the ATM gene. Based on this, we can assume the involvement of ATM in the development of atherosclerosis. "Overload" of the studied regions with transcription factor binding sites (according to ReMapp2022 data) indicate that the tissue-specific nature of methylation of the regulatory regions of the MLH1 and ATM may be associated with expression levels of these genes in a particular tissue. It has been shown that inter-individual differences in the methylation levels of CpG sites are associated with sufficiently distant nucleotide substitutions.

Changes in DNA methylation profile in liver tissue during progression of HCV-induced fibrosis to hepatocellular carcinoma.

In this study we compared methylation levels of 27,578 CpG sites between paired samples of the tumor and surrounding liver tissues with various degrees of damage (fibrosis, cirrhosis) in HCV-induced hepatocellular carcinoma (HCC) patients, as well as between tumor and normal tissue in non-viral HCC patients, using GSE73003 and GSE37988 data from GEODataSets (https://www.ncbi.nlm.nih.gov/). A significantly lower number of differentially methylated sites (DMS) were found between HCC of non-viral etiology and normal liver tissue, as well as between HCC and fibrosis (32 and 40), than between HCC and cirrhosis (2450 and 2304, respectively, according to GSE73003 and GSE37988 datasets). As the pathological changes in the tissue surrounding the tumor progress, the ratio of hyper-/hypomethylated DMSs in the tumor decreases. Thus, in tumor tissues compared with normal/fibrosis/cirrhosis of the liver, 75/62.5/47.7 % (GSE73003) and 16 % (GSE37988) of CpG sites are hypermethylated, respectively. Persistent hypermethylation of the ZNF154 and ZNF540 genes, as well as CCL20 hypomethylation, were registered in tumor tissue in relation to both liver fibrosis and liver cirrhosis. Protein products of the EDG4, CCL20, GPR109A, and GRM8 genes, whose CpG sites are characterized by changes in DNA methylation level in tumor tissue in the setting of cirrhosis and fibrosis, belong to "Signaling by G-protein-coupled receptors (GPCRs)" category. However, changes in the methylation level of the "driver" genes for oncopathology (АРС, CDKN2B, GSTP1, ELF4, TERT, WT1) are registered in tumor tissue in the setting of liver cirrhosis but not fibrosis. Among the genes hypermethylated in tumor tissue in the setting of liver cirrhosis, the most represented biological pathways are developmental processes, cell-cell signaling, transcription regulation, Wnt-protein binding. Genes hypomethylated in liver tumor tissue in the setting of liver cirrhosis are related to olfactory signal transduction, neuroactive ligand-receptor interaction, keratinization, immune response, inhibition of serine proteases, and zinc metabolism. The genes hypermethylated in the tumor are located at the 7p15.2 locus in the HOXA cluster region, and the hypomethylated CpG sites occupy extended regions of the genome in the gene clusters of olfactory receptors (11p15.4), keratin and keratin-associated proteins (12q13.13, 17q21.2, and 21q22.11), epidermal differentiation complex (1q21.3), and immune system function loci 9p21.3 (IFNA, IFNB1, IFNW1 cluster) and 19q13.41-19q13.42 (KLK, SIGLEC, LILR, KIR clusters). Among the genes of fibrogenesis or DNA repair, cg14143055 (ADAMDEC1) is located in the binding region of the HOX gene family transcription factors (TFs), while cg05921699 (CD79A), cg06196379 (TREM1) and cg10990993 (MLH1) are located in the binding region of the ZNF protein family transcription factor (TF). Thus, the DNA methylation profile in the liver in HCV-induced HCC is unique and differs depending on the degree of surrounding tissue lesion - liver fibrosis or liver cirrhosis.

[IMMUNOGENETICS AND PROGRESSION OF CHRONIC VIRAL HEPATITES].

AIM OF INVESTIGATION: To estimate the role of polymorphic variants of genes IL4 (C-590T), IL4RA (I50V), TNF (G-308A) and SLC1IAI (D543N) in chronic viral hepatitis progression. MATERIAL AND METHODS: Overall 121 patients with chronic viral hepatitis C and B. RESULTS: Study results have demonstrated, that of all investigated polymorphic variants of genes IL4 (C-590T), IL4RA (150V), TNF (G-308A) and SLC11A1 (D543N) in patients with chronic liver diseases of various etiology the <> IL4RA gene variant (II50Val) is associated with HBV-infection chronization. The allele <> gene TNF-α (G-308A) is protective for chronic viral hepatitis and is associated with a low level of production by mononuclear cells of TNF-α and IL-12, high secretion of IL-4 and low degree of collagenopathy in the liver. Genotype <> of IL4 (C-590T) gene is an adverse marker for progression of chronic viral hepatitis B. There was significant correlation of polymorphic variants TNF (G-308A) and IL4 (C-590T) genes with production of the key interleukins, that determine type of immune response (Th-1, Th-2) and products of collagen metabolism that testifies genetic determination of system immune response and collagen formation processes in the liver at chronic viral hepatitis.

[The evaluation of association between polymorphisms of DNA excision repair enzyme genes and risk of malignant tumors development in Siberian Group of Chemical Enterprises workers].

There was analyzed single nucleotide polymorphisms of DNA excision repair enzyme genes hOGG, XPD, XPG, XRCC1 in 98 Siberian Group of Chemical Enterprises cancer patients and 148 healthy donors. No association was observed between the analyzed polymorphisms and malignant tumors in both control and subgroup (under study) of persons exposed to occupational ionizing radiation. Heterozygosis for the genes hOGG and XPD was found to be a protective factor to malignant tumors in exposed persons: the odds ratio = 0.42 (95% CI 0.18-0.98; p = 0.044) for the 326Ser/Cys genotype of the hOGG gene and 0.48 (95% CI 0.23-0.99; p = = 0.047) the 751Lys/Gln genotype of the XPD gene. The data obtained show a possible modifying role of the hOGG and XPD gene polymorphisms for malignant tumors risk in exposed persons.

[Association of immune system gene polymorphisms with quantitative features which are pathogenetically important in chronic viral hepatitis].

Association study was performed for genetic polymorphisms IL4 C(-590)T, IL4RA Ile50Val, TNF G(-308)A, to estimate their effect on quantitative features which are pathogenetically important for chronic viral hepatitis course, i.e. levels of IL4, IL10, IL12, tumor necrosis factor alpha, fibronectin, collagenase, protease inhibitors, macroglobulines, elastases, free and protein-bound hydroxyproline. It has been shown that A allele of TNF G(-308)A polymorphism is associated with decreased TNF-alpha, increased IL4 and IL12, as well as with low level of protein-bound hydroxyproline. In addition, association of CT genotype of IL4 C(-590)T polymorphism and high level of protein-bound hydroxyproline has been identified.

[Genetics factors determining predisposition to chronic course of virus hepatitis and fibrosis in liver].

Polymorphic variants of several genes IL4 C(-590)T, IL4RA Ile50Val, TNF G(-308)A were studied for their association with extent of the disease chronization which is marked by hepatic fibrosis stage. Gradual decrease in A allele frequency of polymorphic marker G(-308)A in TNF gene, from patients with weak fibrosis to patients with cirrhosis. Group of patients with weak fibrosis was characterized by higher frequency of A allele (24.5%) comparing with patients with moderate and pronounced fibrosis (13.4%) and cirrhosis (8.7%). Differences in heterozygous genotype frequencies of IL4 C(-590)T were found between patients with cirrhosis (68.2%) and groups of patients with moderate and marked fibrosis (39.1%).

In vivo effect of selective macrophage suppression on the development of intrahepatic cholestasis in mice.

We studied the role of selective suppression of liver Kupffer cells (gadolinium chloride, 14 mg/kg intravenously) in the development of intrahepatic cholestasis in CBA/C57B1/6 mice after intraperitoneal injection of alpha-naphthylisothiocyanate in a single dose of 200 mg/kg. Pretreatment with gadolinium chloride increased the severity of cholestasis and signs of liver damage. Gadolinium accumulation in the liver peaked after 24 h and was accompanied by a decrease in activities of cathepsin D and cathepsin B and concentration of matrix metalloprotease-2. Our results confirm the hypothesis that normal function of Kupffer cells and extracellular matrix plays an important role in cholestasis. Administration of gadolinium chloride serves as a convenient model to study the side effects, toxicity, and safety of lanthanides as nanoparticles.

Influence of opiate addiction on liver cell damage of patients with viral hepatitis C.

Liver functional tests, cholestasis development and serum acute phase proteins, including a-1-proteinase inhibitor (PI) and albumin level (negative reactant of acute phase proteins), C-reactive protein (CRP) have been studied in the patients with viral hepatitis C (HCV) and/or drug addictive disorders (crude home-made opiates). Narcotic drugs were shown to be responsible for aggravation of cholestasis development in HCV patients with opiate addiction. Decreased albumin concentration in serum was registered in all groups with drug addictive disorders, as a result of modified acute phase reaction.