Mitochondrial aging : focus on mitochondrial DNA damage in atherosclerosis : a mini-review

Atherosclerosis is a complex disease which can be described as an excessive fibrofatty, proliferative, inflammatory response to damage to the artery wall involving several cell types such as smooth muscle cells, monocyte-derived macrophages, lymphocytes, dendritic cells and platelets. On the other hand, atherosclerosis is a typical age-related degenerative pathology, which is characterized by signs of cell senescence in the arterial wall including reduced cell proliferation, irreversible growth arrest and apoptosis, increased DNA damage, the presence of epigenetic modifications, shortening of telomere length and mitochondrial dysfunction. The most prominent characteristics of mitochondrial aging are their structural alterations and mitochondrial DNA damage. The mechanisms of mitochondrial genome damage in the development of chronic age-related diseases such as atherosclerosis are not yet well understood. This review focuses on the latest findings from studies of those mutations of the mitochondrial genome which may play an important role in the development of atherosclerosis and which are, at the same time, also markers of mitochondrial aging and cell senescence

MtDNA mutations linked with left ventricular hypertrophy

Aim: In left ventricular hypertrophy (LVH), the heart muscle thickens. One third of individuals with LVH never complain of heart problems. However, such patients have a high risk of sudden death. LVH can be caused by arterial atherosclerotic lesions. The linkage of mtDNA mutations 652insG, m.5178C>A, m.3336T>C, m.14459G>A, 652delG, m.14846G>A, m.1555A>G, m.15059G>A, m.3256C>T, m.12315G>A and m.13513G>A with atherosclerosis was described earlier by our laboratory. The aim of the study was to analyze the linkage of these mtDNA mutations with LVH.Methods: DNA from white blood cells was isolated using a phenol-chloroform method. PCR-fragments of DNA contained the region of the investigated mutations. The heteroplasmy level of mtDNA mutations was analyzed using a pyrosequencing-based method developed by our laboratory.Results: We investigated two groups of individuals. One hundred and ninety-four patients with LVH. Two hundred and ten were conventionally healthy. It was found that mtDNA mutation m.5178C>A was significantly associated with LVH. Single nucleotide replacement m.1555A>G was associated with LVH at the level of significance P ≤ 0.1. At the same time m.12315G>A and m.3336T>C were significantly associated with the absence of this pathology. Single nucleotide replacement m.14459G>A was associated with the absence of LVH at the significance level P ≤ 0.1.Conclusion: MtDNA mutations m.5178C>A and m.1555A>G can be used for molecular genetic assessment of the predisposition of individuals to the occurrence of left ventricular hypertrophy. They can also be used for the family analysis of this pathology. Mutations m.12315G>A, m.3336T>C and m.14459G>A can be used in the development of LVH gene therapy methods

The Role of Mitochondrial Mutations in Chronification of Inflammation: Hypothesis and Overview of Own Data

Chronic human diseases, especially age-related disorders, are often associated with chronic inflammation. It is currently not entirely clear what factors are responsible for the sterile inflammatory process becoming chronic in affected tissues. This process implies impairment of the normal resolution of the inflammatory response, when pro-inflammatory cytokine production ceases and tissue repair process begins. The important role of the mitochondria in the correct functioning of innate immune cells is currently well recognized, with mitochondrial signals being an important component of the inflammatory response regulation. In this work, we propose a hypothesis according to which mitochondrial DNA (mtDNA) mutations may play a key role in rendering certain cells prone to prolonged pro-inflammatory activation, therefore contributing to chronification of inflammation. The affected cells become sites of constant pro-inflammatory stimulation. The study of the distribution of atherosclerotic lesions on the surface of the arterial wall samples obtained from deceased patients revealed a focal distribution of lesions corresponding to the distribution of cells with altered morphology that are affected by mtDNA mutations. These observations support the proposed hypothesis and encourage further studies

Association of mitochondrial mutations with the age of patients having atherosclerotic lesions

Mitochondrial genome mutations are associated with different pathologies. Earlier the authors of the study found an association of some mitochondrial genome mutations with atherosclerosis. In the present study, an attempt to analyze a connection of detected mutations with the age of patients with atherosclerosis was made. The investigated sample included 700 individuals, examined by ultrasonography in polyclinics of Moscow and the Moscow region. The sample was divided approximately into two equal parts. The first part included patients with carotid atherosclerosis. The second part included conventionally healthy study participants. In PCR-fragments of individuals' DNA the heteroplasmy level of investigated mutations was quantitatively measured by the method, developed by members of our laboratory on the basis of pyrosequencing technology. According to the obtained results mutations G12315A, G14459A and G15059A were significantly associated with the age of the study participants. The same time one nucleotide replacements A1555G and G14846A correlated negatively with the age at a high level of significance. Thus, in the present study an association of atherogenic mitochondrial genome mutations with age was found. Antiatherogenic mutations were correlated with the age negatively. This prompts a suggestion about common mechanisms of atherogenesis and aging

Some Molecular and Cellular Stress Mechanisms Associated with Neurodegenerative Diseases and Atherosclerosis

Chronic stress is a combination of nonspecific adaptive reactions of the body to the influence of various adverse stress factors which disrupt its homeostasis, and it is also a corresponding state of the organism’s nervous system (or the body in general). We hypothesized that chronic stress may be one of the causes occurence of several molecular and cellular types of stress. We analyzed literary sources and considered most of these types of stress in our review article. We examined genes and mutations of nuclear and mitochondrial genomes and also molecular variants which lead to various types of stress. The end result of chronic stress can be metabolic disturbance in humans and animals, leading to accumulation of reactive oxygen species (ROS), oxidative stress, energy deficiency in cells (due to a decrease in ATP synthesis) and mitochondrial dysfunction. These changes can last for the lifetime and lead to severe pathologies, including neurodegenerative diseases and atherosclerosis. The analysis of literature allowed us to conclude that under the influence of chronic stress, metabolism in the human body can be disrupted, mutations of the mitochondrial and nuclear genome and dysfunction of cells and their compartments can occur. As a result of these processes, oxidative, genotoxic, and cellular stress can occur. Therefore, chronic stress can be one of the causes forthe occurrence and development of neurodegenerative diseases and atherosclerosis. In particular, chronic stress can play a large role in the occurrence and development of oxidative, genotoxic, and cellular types of stress

Potential use of buccal epithelium for genetic diagnosis of atherosclerosis using mtDNA mutations

Aim: The aim of this pilot study was to compare the heteroplasmy levels of specific mitochondrial (mt)DNA mutations in human buccal epithelial and whole blood cells in participants with different degrees of predisposition to atherosclerosis. The potential for buccal epithelium to be used for the genetic diagnosis of atherosclerosis using mtDNA mutations was assessed.Methods: Samples of buccal epithelial and whole blood cells were obtained from 134 donors. DNA was extracted from the samples and subjected to polymerase chain reaction and pyrosequencing. The threshold heteroplasmy levels of the mutations m.12315G>A, m.3336T>C, m.1555А>G, m.13513G>A, and m.3256C>T were analyzed in order to assess the potential for using buccal epithelium and whole blood for the genetic diagnosis of atherosclerosis.Results: The threshold heteroplasmy levels of the assessed mitochondrial mutations did not significantly differ between buccal epithelial and whole blood cells.Conclusion: Buccal epithelial cells may be preferable to whole blood cells for analyzing the association of mitochondrial genome mutations with atherosclerosis

Some Molecular and Cellular Stress Mechanisms Associated with Neurodegenerative Diseases and Atherosclerosis

Chronic stress is a combination of nonspecific adaptive reactions of the body to the influence of various adverse stress factors which disrupt its homeostasis, and it is also a corresponding state of the organism’s nervous system (or the body in general). We hypothesized that chronic stress may be one of the causes occurence of several molecular and cellular types of stress. We analyzed literary sources and considered most of these types of stress in our review article. We examined genes and mutations of nuclear and mitochondrial genomes and also molecular variants which lead to various types of stress. The end result of chronic stress can be metabolic disturbance in humans and animals, leading to accumulation of reactive oxygen species (ROS), oxidative stress, energy deficiency in cells (due to a decrease in ATP synthesis) and mitochondrial dysfunction. These changes can last for the lifetime and lead to severe pathologies, including neurodegenerative diseases and atherosclerosis. The analysis of literature allowed us to conclude that under the influence of chronic stress, metabolism in the human body can be disrupted, mutations of the mitochondrial and nuclear genome and dysfunction of cells and their compartments can occur. As a result of these processes, oxidative, genotoxic, and cellular stress can occur. Therefore, chronic stress can be one of the causes forthe occurrence and development of neurodegenerative diseases and atherosclerosis. In particular, chronic stress can play a large role in the occurrence and development of oxidative, genotoxic, and cellular types of stress

Carotid atherosclerosis-related mutations of mitochondrial DNA do not explain the phenotype of metabolic syndrome

Aim: This study was undertaken to explore the relationship between metabolic syndrome (MetS) and atherosclerosis-related mitochondrial DNA (mtDNA) mutations, since MetS shares conventional and genetic risk factors with atherosclerosis.Methods: The study involved 220 participants; the carotid ultrasonography followed by intima-media thickness (cIMT) measurement was used for quantitative diagnostics of carotid atherosclerosis. The diagnosis of MetS was set according to International Diabetes Federation criteria (IDF-2009). The level of mtDNA heteroplasmy in leukocytes was determined by qPCR. The severity of MetS was estimated on combination of serum HDL cholesterol, triglycerides and fasting glucose, systolic and diastolic blood pressure, and waist circumference measurements.Results: MetS was present in 44 study participants. Ten mtDNA mutations were tested, and m.3336T>C and m.652delG heteroplasmy levels correlated with the clusterization of MetS symptoms, in particular the cardiovascular and metabolic risk factors, of triglyceride and fasting glucose levels. The other mtDNA mutations each only correlated with one symptom (i.e., m.652delG and m.12315G>A-with triglycerides; m.3256C>T, m.1555A>G, and m.15059G>A-with systolic blood pressure; m.14846G>A-with fasting glucose). There was no correlation between integral severity of MetS and cIMT.Conclusion: In this study, the MetS phenotype was not explained directly by atherosclerosis-related mtDNA variants. It is possible to hypothesize that mtDNA-related mechanisms in atherosclerosis and MetS may be different, in spite of the similarity of several phenotypic characteristics

Cybrid Models of Pathological Cell Processes in Different Diseases

Modelling of pathological processes in cells is one of the most sought-after technologies of the 21st century. Using models of such processes may help to study the pathogenetic mechanisms of various diseases. The aim of the present study was to analyse the literature, dedicated to obtaining and investigating cybrid models. Besides, the possibility of modeling pathological processes in cells and treatment of different diseases using the models was evaluated. Methods of obtaining Rho0 cell cultures showed that, during their creation, mainly a standard technique, based on the use of mtDNA replication inhibitors (ethidium bromide), was applied. Cybrid lines were usually obtained by PEG fusion. Most frequently, platelets acted as donors of mitochondria. According to the analysis of the literature data, cybrid cell cultures can be modeled to study the dysfunction of the mitochondrial genome and molecular cellular pathological processes. Such models can be very promising for the development of therapeutic approaches to the treatment of various human diseases