[Endothelial dysfunction as a pathogenetic factor of sensorineural hearing loss]

Chronic sensorineural hearing loss (SNHL) is a common disease that leads to disability of the population. Despite the many reports devoted to SNHL, the question of the pathogenesis of the disease is still open. Many researchers consider the development of SNHL as a manifestation of microangiopathy. The mechanism of development of microangiopathy in SNHL is multifactorial, but most researchers agree that endothelial dysfunction (ED) triggers a complex of pathological changes in the vessels of the inner ear.

OBJECTIVE

Review of the results of scientific research in recent years on the problem of etiopathogenesis of sensorineural hearing loss from the perspective of endothelial dysfunction in the formation of auditory disorders.

Endothelial dysfunction: developmental mechanisms and therapeutic strategies

Introduction: Every year the importance of the normal functioning of the endothelial layer of the vascular wall in maintaining the health of the body becomes more and more obvious.

The physiological role of the endothelium: The endothelium is a metabolically active organ actively involved in the regulation of hemostasis, modulation of inflammation, maintenance of hemovascular homeostasis, regulation of angiogenesis, vascular tone, and permeability.

Risk factors for the development of endothelial dysfunction: Currently, insufficient bioavailability of nitric oxide is considered the most significant risk factor for endothelial dysfunction.

Mechanisms of development of endothelial dysfunction: The genesis of endothelial dysfunction is a multifactorial process. Among various complex mechanisms, this review examines oxidative stress, inflammation, hyperglycemia, vitamin D deficiency, dyslipidemia, excess visceral fat, hyperhomocysteinemia, hyperuricemia, as well as primary genetic defect of endotheliocytes, as the most common causes in the population underlying the development of endothelial dysfunction.

Markers of endothelial dysfunction in various diseases: This article discusses the main biomarkers of endothelial dysfunction currently used, as well as promising biomarkers in the future for laboratory diagnosis of this pathology.

Therapeutic strategies: Therapeutic approaches to the endothelium in order to prevent or reduce a degree of damage to the vascular wall are briefly described.

Conclusion: Endothelial dysfunction is a typical pathological process involved in the pathogenesis of many diseases. Thus, pharmacological agents with endothelioprotective properties can provide more therapeutic benefits than a drug without such an effect.

To study the dynamics of serum levels of vascular remodeling in patients with hypertension, including in combination with type 2 diabetes mellitus during 12‑month therapy with perindopril A

Aim      To study the dynamics of serum markers for vascular remodeling in patients with arterial hypertension (AH), including AH associated with type 2 diabetes mellitus (DM2) during the 12-month treatment with the angiotensin-converting enzyme (ACE) inhibitor, perindopril A.Material and methods  The study included patients with grade 1-2 AH with or without type 2 DM (30 and 32, respectively). Perindopril A 10 mg/day was administered for the outpatient correction of previous, ineffective antihypertensive therapy. The following biomarkers were measured for all patients at baseline and at 12 months: matrix metalloproteinase-9 (MMP-9), tissue inhibitor of metalloproteinase-1 (TIMP-1), E-selectin, endothelin 1, transforming growth factor β-1 (TGF-β1), and von Willebrand factor (WF). Laboratory tests were performed with enzyme immunoassay.Results After 12 months of the perindopril A (perindopril arginine) 10 mg/day treatment, both groups achieved the goal blood pressure. Evaluation of biomarker dynamics during the perindopril A treatment showed significant decreases in MMP-9, TIMP-1, and endothelin 1 in the AH group; then the level of TIMP-1 returned to normal values (р<0.05). In the AH+DM2 group, the MMP-9 concentration was significantly decreased (р<0.05); the other values did not show any significant differences. In both groups, MMP-9 was significantly decreased (28.6 % (р=0.01) in group 1 and 33.2 % (р=0.00) in group 2. Notably, in none of these groups, did this index reach normal values. Also, there were no significant differences in this index between the groups (р=0.66). It should be noted that the decreases in TIMP-1 were significantly different between the groups (р=0.001). Thus, this biomarker did not significantly decrease in patients with AH and DM2 (р=0.26) whereas in group 1 (AH without DM2), the level of TIMP-1 decreased by 39.3 % and reached the normal range (р=0.005).Conclusion      Concentrations of biomarkers were decreased in both groups. However, in the AH group, there were statistically significant decreases in the markers that reflect processes of fibrosis and vasoconstriction. At the same time in the AH+DM2 group, there was no significant dynamics of the biomarkers, which was most likely due to more pronounced damage of blood vessels. However, the decrease in MMP-9 may indicate an alleviation of fibrotic processes in arterial walls. These results allow a conclusion that the long-term treatment with the ACE inhibitor, perindopril A, may reverse remodeling of the vascular changes that are called "early vascular ageing".r aging".

Indicators of endothelial function and systemic immune inflammatory response in patients with chronic heart failure and coexisting primary hypothyroidism

Chronic heart failure is one of the leading causes of death globally, affecting 1.5 to 2% of the total world population and 2.9 to 3.9% of the total Western European population. Chronic heart failure often progresses rapidly in coexistence with endocrine pathology, namely hypothyroidism, that results in a more rapid development and further progression of endothelial dysfunction and the development of a systemic inflammatory response. The aim of our research was to study the levels of endothelin-1, C-reactive protein, tumor necrosis factor α and their correlation with the levels of thyroid-stimulating hormone, thyroxine in patients with chronic heart failure and coexisting hypothyroidism. There were examined 38 patients with chronic heart failure and coexisting hypothyroidism and 42 patients with chronic heart failure without hypothyroidism. The serum levels of endothelin-1, C-reactive protein, tumor necrosis factor α were determined by the enzyme-linked immunosorbent assay, while the levels of thyroid-stimulating hormone and thyroxine were determined by the electrochemiluminescence immunoassay. In patients with chronic heart failure and coexisting hypothyroidism, the levels of endothelin-1, C-reactive protein, and tumor necrosis factor α were 2.9, 1.5 and 2.27 times higher than those in patients without hypothyroidism. In Group I, there was a moderate positive correlation between the serum levels of endothelin-1 and thyroid-stimulating hormone and a weak negative correlation between the levels of thyroxine and endothelin-1. In Group II, there was a weak correlation between the levels of endothelin-1 and thyroid-stimulating hormone and no correlation between the levels of thyroxine and endothelin-1. In Group I, there was a strong positive correlation between C-reactive protein and thyroid-stimulating hormone levels as well; in Group II, no similar correlation was found. In Group I, there was found a moderate negative correlation between tumor necrosis factor α and thyroxine levels. According to our results, there was a close correlation between the markers of endothelial dysfunction, immune inflammatory response, and single markers of hypothyroidism.

[Markers of endothelial dysfunction in patients with arterial hypertension exposed to occupational irradiation of low intensity]

Aim To study the association between concentrations of endothelial dysfunction (ED) markers and arterial hypertension (AH) in people who were exposed to long-term action of "low-dose" ionizing radiation.Material and methods The study subjects were men of middle age (45-55 years) who were workers of the Siberian Integrated Chemical Plant with the length of service on the shop floor of at least 5 years. The subjects were divided into the main group (n=96) consisting of workers with grade 1-2 AH and the control group (n=48) consisting of arbitrarily healthy workers. Both groups contained workers who had been exposed to long-term occupational low-intensity irradiation (γ-radiation) and those not exposed to this irradiation. The study evaluated risk factors for cardiovascular diseases, presence of concomitant diseases, blood biochemistry (concentrations of glucose, high-sensitivity C-reactive protein (hsCRP), total cholesterol, low-density lipoproteins, high-density lipoproteins, triglycerides, creatinine, and ED markers, including endothelin, angiotensin II, von Willebrand factor, C-type natriuretic peptide, tissue plasminogen activator, tumor necrosis factor α (TNF-α), and homocysteine, major clinical data, total dose of external irradiation, and the content of 239Pu in the body.Results AH was associated primarily with excessive body weight and severity of atherogenic dyslipidemia and homocysteinemia. Higher plasma concentrations of TNF-α and a tendency to increasing hsCRP in the AH group, as distinct from the control group of arbitrarily healthy men, indicated a proinflammatory shift. The ED markers were related with clinical data of AH patients and associated with the lipid profile and increased blood concentrations of inflammatory mediators. The radiation exposure did not change the ED marker array in AH patients, which did not allow recommendation of the studied plasma indexes for detection of vascular endothelial injury in workers with AH of the Siberian Integrated Chemical Plant.Conclusion The study results evidenced the absence of adverse effects of long-term occupational exposure to low-intensity radiation on the vascular endothelium as evaluated by ED markers. In men aged 45-55 years, AH was associated primarily with excessive body weight, homocysteinemia, and atherogenic dyslipidemia.

Endothelial dysfunction: from the particular to the general. Return to the «Old Paradigm»?

The vascular endothelium is a heterogeneous structure with diverse functions, being an active metabolic system. Endothelial cells mediate inflammatory and immune processes, regulate leukocyte adhesion, permeability and vascular tone, participate in the hemostasis system, stimulate the processes of angiogenesis. Endothelial dysfunction can initiate individual disorders, but more often it is a universal link in the pathogenesis of many diseases. Currently, endothelial dysfunction is presented as an imbalance between the production of vasodilating, angioprotective, antiproliferative factors, on the one hand, and vasoconstrictive, prothrombotic, proliferative factors, on the other hand. The manifestations of endothelial dysfunction, the direction and severity of these changes may vary depending on the disease. The review provides examples of combined endothelial disorders in the most studied and common diseases (essential hypertension, type 2 diabetes, systemic diseases of the connective tissue, atherosclerosis, and malignant tumors). Despite the presence of rare cases of isolated endothelial dysfunction, it can be argued that in the absolute majority of diseases, endothelial dysfunction has combined type of violations. The allocation of individual endothelial disorder spectra, typical for a specific disease, is problematic, due to the universality and nonspecificity of the manifestations of endothelial dysfunction. These conclusions allow us to return to the origins of this problem, considering endothelial dysfunction as a holistic concept, not limited to a certain range of its disorders.