Aldosterone synthase gene polymorphism in alimentary obesity, metabolic syndrome components, some secondary forms of arterial hypertension, pathology of the adrenals glands core (literature review)
Journal Title: Актуальна інфектологія - Year 2017, Vol 13, Issue 5
Abstract
Hormonal factors of adrenal origin belong to the pathophysiological mechanisms of the formation and progression of arterial hypertension (AH) and should be considered while developing differentiated approaches to the treatment and prevention of hypertensive states, their primary, secondary and resistant forms. The first thing we should point up is aldosterone (AL), enzyme aldosterone synthase (AS), which takes a direct part in the formation of this hormone, as well as gene polymorphisms of AS, which have not only molecular genetic, but also differential diagnostic and therapeutic significance for secondary forms of arterial hypertension, abdominal obesity (AO), metabolic syndrome (MS), adrenal pathology and other endocrine disorders. AL is a steroid (mineralocorticoid) hormone of the adrenal cortex, which is synthesized from cholesterol (CH), mainly in the glomerular zone of the adrenal glands, is released under the action of angiotensin II (A II) and potassium ions (K+). AL activity is mediated through the corresponding mineralocorticoid receptors (MKR). The particular importance in AH and MS development belongs to AL activation and MKR density in adipocytes, this phenomenon is accompanied by increased expression of pro-inflammatory cytokines, leptin, an adipogenic effect, and the inhibition of MCR activity is accompanied by increased production of adiponectin, which is more pronounced in patients with AH. Aldosterone synthase, a mitochondrial human enzyme encoded by the CYP11B2 gene (cytochrome P450, family 11, subfamily B, polypeptide 2) is located on the 8th chromosome. AS belongs to the superfamily of cytochrome P450 and regulates the synthesis of AL hormone. The CYP11B2 gene encodes the key enzyme for the synthesis of AL 18-hydroxylase. In scientific papers, single nucleotide polymorphism (SNP) of AS gene is often studied, such as 5312T, Intron 2, Lys-173/Arg; T-344C, 3097 C/A. 227 SNP of the AS gene were identified in different populations. Europeans, Asians, Africans and North Americans were among them and were genotyped by CYP11B2. To date, there is ample evidence that fatty tissue (FT), apart from a source of energy, is an active endocrine organ that plays a key role in maintaining homeostasis and participating in the pathogenesis of a number of diseases. Its excess is accompanied by hyperactivation of tissue renin-angiotensin-aldosterone system (RAAS), strengthening of local and systemic synthesis of AL and the emergence of secondary aldosteronism. AL, in its turn, has a direct effect on FT due to increased MKR density expressed on adipocytes surface, leading to acceleration in the maturation of the latter and a further increase in FT. Getting into the systemic blood circulation and effecting other organs, the excess AL promotes the development of insulin resistance, atherosclerosis, the progression of systemic inflammatory reactions. MKR activation in FT plays not only the key role in sodium reabsorption by kidneys and the control of BP, but also in the differentiation of preadipocytes into mature adipocytes in FT, induction of inflammation and hyperproduction of cytokines — tumor necrotic factor alpha (TNF-α), monocyte chemotactic protein (MCP-1) and interleukin 6 (IL-6) in the white FT, a decrease in the thermogenic activity and transcription of the uncoupling protein-1 (UCP-1) in brown FT. MCR hyperactivation was detected in mice with AO (obese db/db mice), associated with increased BMI in humans and contributes to the development of IR and associated with AO cardiovascular diseases. The gene polymorphism of AS may be a marker of aggravated pregnancy, the presence of gestational hypertension or pre-eclampsia. Some studies found that AS gene polymorphism can affect plasma glucose levels. AS gene polymorphism was not associated with the progression of diabetic nephropathy (DN), but is associated with AH in persons with type 2 diabetes mellitus. National authors conclude about the association of the genotype TT(-344) of the gene CYP11B2 with the risk of MS among residents of the North-West region of Russia. The carrier of 344T allele of AS gene in patients with AO was associated with an increased risk of hypertension development. The features of AS gene polymorphism and blood levels in acromegaly have been studied, and the allelic polymorphism of AS and chymase genes (CMA) has been analyzed to identify the possible association of alleles of these genes with secondary hypertension and hyperaldosteronism in Russians. The congenital defects of the enzymatic activity of AS are of undoubted interest. AS gene is a promising candidate gene in the European and Asian populations for a number of secondary forms of hypertension, MS, diabetes mellitus, abdominal obesity, renal pathology, diabetic nephropathy, gestational hypertension. Genotyping of AS gene polymorphisms can be useful in differential diagnostic in patients with secondary forms of arterial hypertension, hypertension with low plasma renin activity, renovascular and resistant hypertension, adrenal tumors, primary and secondary hyperaldosteronism, aldosteromas, imaginary excess of mineralcorticoids syndrome, congenital hyperplasia of adrenal cortex. The advantages and disadvantages of the therapeutic use of MCR antagonists and the prospects for the administration of aldosterone synthase inhibitors among various categories of patients are considered. Carrying out the genotyping of patients by the CYP11B2 gene before therapy starting will allow take into account the genetic factors of sensitivity to drug in patients with the phenomenon of arterial hypertension and endocrine disorders. New AS inhibitors will not only effectively reduce blood pressure, but also will be able to prevent the development of adverse humoral and hormonal changes, what will prolong the life of patients and will help to reduce the level of total mortality from this pathology.
Authors and Affiliations
S. N. Koval, D. K. Miloslavsky, I. A. Snegurskaya, O. V. Mysnichenko, M. Yu. Penkova
Keywords
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- EP ID EP224869
- DOI 10.22141/2224-0721.13.5.2017.110026
- Views 98
- Downloads 0
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