Renin-angiotensin system gene polymorphisms as risk factors for multiple sclerosis

Sodium chloride-induced changes in oxidative stress, inflammation, and dysbiosis in experimental multiple sclerosis

Objectives: The high-salt diet (HSD) has been associated with cognitive dysfunction by attacking the cerebral microvasculature, through an adaptive response, initiated in the intestine and mediated by Th17 cells. In the animal model of multiple sclerosis (MS), experimental autoimmune encephalomyelitis (EAE), it has been described that NaCl causes an increase in T cell infiltration in the central nervous system. NaCl also promotes macrophage response and Th17 cell differentiation, worsening the course of the disease. HSD may trigger an activation of the immune system and enhance inflammation. However, certain studies not only do not support this possibility, but support the opposite, as the effect of salt on immune cells may not necessarily be pathogenic. Therefore, this study aimed to evaluate the effect of an over intake of salt in rats with EAE, based on the clinical course, oxidative stress, markers of inflammation and the gut dysbiosis.Methods: 15 Dark Agouti rats were used, which were divided into control group, EAE group and EAE + NaCl group. Daily 0.027 g of NaCl dissolved in 300 μl of H2O was administered through a nasogastric tube for 51 days.Results: NaCl administration produced an improvement in clinical status and a decrease in biomarkers of oxidative stress, inflammation, and dysbiosis.Conclusion: The underlying mechanism by which NaCl causes these effects could involve the renin-angiotensin-aldosterone system (RAAS), which is blocked by high doses of salt.

Exploring AT2R and its polymorphism in different diseases: An approach to develop AT2R as a drug target beyond hypertension

The Angiotensin II type 2 receptor (AT2R) is one of the critical components of the renin-angiotensin system (RAS), which performs diverse functions like inhibiting cell differentiation, cell proliferation, vasodilatation, reduces oxidative stress and inflammation. AT2R is relatively less studied in comparison to other components of RAS despite its uniqueness (sex-linked) and diverse functions. The AT2R is differentially expressed in different tissues, and its gene polymorphisms are associated with several diseases. The molecular mechanism behind the association of AT2R and its gene polymorphisms with the diseases remains to be fully understood, which hinders the development of AT2R as a drug target. Single nucleotide polymorphisms (SNPs) in AT2R are found at different locations (exons, introns, promoter, and UTR regions) and were studied for association with different diseases. There may be different mechanisms behind these associations as some AT2R SNP variants were associated with differential expression, the SNPs (A1675G/A1332G) affect the alternate splicing of AT2R mRNA, A1332G genotype results in shortening of the AT2R mRNA and subsequently defective protein. Few SNPs were found to be associated with the diseases in either females (C4599A) or males (T1334C). Several other SNPs were expected to be associated with other similar/related diseases, but studies have not been done yet. The present review emphasizes on the significance of AT2R and its polymorphisms associated with the diseases to explore the precise role of AT2R in different diseases and the possibility to develop AT2R as a potential drug target.

ACE2, TMPRSS2, and Furin variants and SARS-CoV-2 infection in Madrid, Spain

It has been suggested that some individuals may present genetic susceptibility to SARS-CoV-2 infection, with particular research interest in variants of the ACE2 and TMPRSS2 genes, involved in viral penetration into cells, in different populations and geographic regions, although insufficient information is currently available. This study addresses the apparently reasonable hypothesis that variants of these genes may modulate viral infectivity, making some individuals more vulnerable than others. Through whole-exome sequencing, the frequency of exonic variants of the ACE2, TMPRSS2, and Furin genes was analyzed in relation to presence or absence of SARS-CoV-2 infection in a familial multiple sclerosis cohort including 120 individuals from Madrid. The ACE2 gene showed a low level of polymorphism, and none variant was significantly associated with SARS-CoV-2 infection. These variants have previously been detected in Italy. While TMPRSS2 is highly polymorphic, the variants found do not coincide with those described in other studies, with the exception of rs75603675, which may be associated with SARS-CoV-2 infection. The synonymous variants rs61735792 and rs61735794 showed a significant association with infection. Despite the limited number of patients with SARS-CoV-2 infection, some variants, especially in TMPRSS2, may be associated with COVID-19.

Angiotensin II type 2 receptor gene polymorphisms and serum angiotensin-converting enzyme level in Egyptian children with systemic lupus erythematosus

Background

There are no reports about the association of angiotensin II type 2 receptor ( AT2R) gene polymorphisms and susceptibility to systemic lupus erythematosus (SLE) in children.

Objective

The objective of this research is to study AT2R gene polymorphisms in exon 3 (C1593A) and intron 1 (A1675G) in Egyptian children with SLE and its correlation with disease manifestations and serum angiotensin-converting enzyme (ACE) level.

Methods

Typing of AT2R gene polymorphisms was conducted in 123 children with SLE in comparison with 100 healthy controls using the restriction fragment length polymorphism method.

Results

Significant differences were found between SLE patients and controls for A-containing genotypes (CA + AA) and A-allele frequencies of AT2R in exon 3 (C1593A) ( p = 0.01, odds ratio (OR) = 2.5, 95% confidence interval (CI) = 1.3–5.05; p = 0.01, OR = 2.2, 95% CI = 1.2–4.1, respectively). G-containing genotypes (AG + GG) and G allele of AT2R in intron 1 (A1675G) were more frequent in SLE patients compared to controls ( p = 0.01, OR = 2.3, 95% CI = 1.2–4.5; p = 0.02, OR = 2.1, 95% CI = 1.2–3.7, respectively). Serum ACE level was significantly higher in SLE patients than in controls ( p < 0.001). There was no association between AT2R gene polymorphisms and ACE level in serum. Moreover, there was no association between AT2R gene polymorphisms and SLE clinical manifestations.

Conclusion

AT2R gene polymorphisms can be considered risk factors for SLE development in Egyptian children.

Polymorphisms in the angiotensin I converting enzyme (ACE) gene are associated with multiple sclerosis risk and response to Interferon-β treatment

BACKGROUND

Multiple sclerosis (MS) as a chronic autoimmune demyelinating disorder of the central nervous system has been associated with numerous genetic and environmental factors among them are functional variants within the angiotensin I converting enzyme (ACE) gene.

METHODS

In the present study, we genotyped the rs4359 (C/T) and rs1799752 (Insertion (I)/Deletion (D)) of this gene in 391 MS patients and 380 age- and sex-matched controls.

RESULTS

We found significant overrepresentation of the I allele of the rs1799752 in MS patients compared with healthy subjects (Adjusted P value = 0.03, OR (95% CI) = 1.28 (1.05-1.57). The same allele was associated with MS risk in co-dominant and dominant models (Adjusted P values of 0.007 and 0.002 respectively). The allele and genotype frequencies of the rs4359 were not significantly different between cases and controls. Moreover, the I allele of the rs1799752 was significantly overrepresented in MS patients who were irresponsive to IFN-β compared with healthy subjects (Adjusted P value = 0.04, OR (95% CI) = 1.57 (1.08-2.29)). The same allele was associated with irresponsiveness to IFN-β in dominant model (Adjusted P value = 0.02, OR (95% CI) = 2.32 (1.22-4.42)).

CONCLUSION

The present study provides further evidences for the role of ACE in MS risk or response of patients to IFN-β treatment.

Drugs approved for the treatment of multiple sclerosis: review of their safety profile

INTRODUCTION

Multiple sclerosis (MS) is a chronic immune-mediated inflammatory disorder of the brain and spinal cord characterized by inflammation, demyelination, and axonal degeneration. Area covered: Even though the pharmacological armamentarium for MS treatment is considerably improved in the last 20 years, safety data especially for the second-line and innovative treatments are lacking. In order to analyze the safety profile of drugs used for the treatment of MS, a literature review of pre-marketing, post-marketing studies and case reports was performed. Expert opinion: Nowadays, the numerous drugs approved in the last years for the treatment of MS allow a better control of the disease and a better patient compliance. The main advantages of the new disease-modifying agents for MS (DMTs), in fact, derive from the new oral administration and the prolonged half-life with consequent improvement in compliance compared to first-line therapy which required subcutaneous administrations. However, DMTs can cause serious, sometimes life-threatening or fatal, drug adverse reactions. Due to the lack of safety data and given the recent marketing approval of the last DMTs for MS, observational studies and post-marketing surveillance activities will be necessary in order to improve the knowledge about the safety profile of these drugs and the improvement of their use in clinical practice.

Renin-angiotensin-aldosterone (RAAS): The ubiquitous system for homeostasis and pathologies

Renin-angiotensin-aldosterone system (RAAS) is a vital system of human body, as it maintains plasma sodium concentration, arterial blood pressure and extracellular volume. Kidney-secreted renin enzyme acts on its substrate to form angiotensin II, a versatile effector peptide hormone. Every organ is affected by RAAS activation and the resultant hypertension, cell proliferation, inflammation, and fibrosis. The imbalance of renin and angiotensin II can result in an overwhelming number of chronic and acute diseases. RAAS is influenced by other enzymes, hormones, pumps and signaling pathways, hence, this review discusses important facets of this system, its crosstalk with other crucial factors like estrogen, thyroid, cortisol, kallikrein-kinin system, Wnt/β-catenin signaling, and sodium-potassium pump. The nexus of RAAS with the above-discussed systems was scantily explored before. So, this review furnishes a new perspective in comprehension of inflammation diseases. It is followed by the formulation of hypotheses, which can contribute to better management of an array of pathologies plaguing mankind. Manipulation of RAAS, by bending it towards ACE2 expression can regulate endocrine functions, which can be critical for a number of pathological management. Dietary intervention can restore RAAS to normalcy.

Angiotensin-converting enzyme insertion/deletion gene polymorphism and interferon-β treatment response in multiple sclerosis patients: a preliminary report

We investigated the effect of the functional insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme (ACE) gene on the response to interferon-β (IFN-β) therapy in Croatian and Slovenian patients with multiple sclerosis (MS). A total of 275 IFN-β treated MS patients [162 responders (Rs) and 113 nonresponders (NRs)] were genotyped by PCR. The ACE I/D genotype distribution and allele frequencies did not differ between female Rs and NRs. However, male NRs tended to have a greater prevalence of the DD genotype (P=0.073; odds ratio: 2.64; 95% confidence interval: 0.91-7.60) and a significantly higher frequency of the D allele (P=0.022; odds ratio: 2.43; 95% confidence interval: 1.13-5.20) than male Rs. Multiple forward stepwise regression analysis indicated that the negative response to IFN-β therapy was associated with the ACE-DD genotype in men (β=0.371; multiple R change: 0.132; P=0.009) and a higher pretreatment relapse rate in both men (β=-0.438; multiple R change: 0.135; P=0.015) and women (β=-0.208; multiple R change: 0.042; P=0.034). The ACE I/D polymorphism and pretreatment relapse rate accounted for ∼26.7% of the IFN-β response variability among the men in the sample. Further studies of a larger number of MS patients from different populations are necessary to evaluate these preliminary findings.

Macrophages in neuroinflammation: role of the renin-angiotensin-system

Macrophages are essential players of the innate immune system which are involved in the initiation and progression of various inflammatory and autoimmune diseases including neuroinflammation. In the past few years, it has become increasingly clear that the regulation of macrophage responses by the local tissue milieu is also influenced by mediators which were first discovered as regulators in the nervous or also cardiovascular system. Here, the renin-angiotensin system (RAS) is a major focus of current research. Besides its classical role in blood pressure control, body fluid, and electrolyte homeostasis, the RAS may influence (auto)immune responses, modulate T cells, and particularly act on macrophages via different signaling pathways. Activation of classical RAS pathways including angiotensin (Ang) II and AngII type 1 (AT₁R) receptors may drive pro-inflammatory macrophage responses in neuroinflammation via regulation of chemokines. More recently, alternative RAS pathways were described, such as binding of Ang-(1-7) to its receptor Mas. Signaling via Mas pathways may counteract some of the AngII/AT₁R-mediated effects. In macrophages, the Ang-(1-7)/Mas exerts beneficial effects on neuroinflammation via modulating macrophage polarization, migration, and T cell activation in vitro and in vivo. These data delineate a pivotal role of the RAS in inflammation of the nervous system and identify RAS modulation as a potential new target for immunotherapy with a special focus on macrophages.

The lack of association between angiotensin-converting enzyme gene insertion/deletion polymorphism and nicotine dependence in multiple sclerosis

OBJECTIVE

Blood-borne angiotensin II is generated from angiotensinogen via cleavage by renin and angiotensin-converting enzyme (ACE), an enzymatic cascade known as the renin-angiotensin system (RAS). Several lines of evidence indicate that ACE, beyond its classical role of mediating blood pressure regulation, might contribute to the etiology of substance addictions by influencing dopaminergic signaling. A functional insertion/deletion (I/D) polymorphism of the ACE gene was associated with risk for being a smoker among individuals with depression and with smoking severity in studies comprising patients with depression and healthy controls. Several reports have described significantly increased ACE activity in cerebrospinal fluid and serum among MS patients. Furthermore, in our previous work with MS patients from Croatian and Slovenian populations, we demonstrated that the ACE-I/D polymorphism contributes to an elevated MS risk among male patients. Here we investigated whether the ACE-I/D polymorphism might influence smoking behavior among patients with MS.

PATIENTS AND METHODS

Genotyping was performed in 521 patients (males/females: 139/382) using polymerase chain reaction.

RESULTS

We revealed no significant differences in ACE genotype and allele frequencies between smokers and nonsmokers and no significant association between the ACE-I/D polymorphism and either pack-year smoking history or number of cigarettes smoked daily (p > .05, respectively).

CONCLUSION

The ACE-I/D polymorphism does not contribute either to risk for nicotine dependence or to smoking severity among MS patients. In the context of reports on the ACE-I/D polymorphism and nicotine dependence among healthy controls and patients with depression, we may speculate that the mechanism by which this polymorphism influences nicotine dependence risk differs in MS compared to depression, although not compared to a healthy population. In addition to angiotensin II, other potential ACE substrates, such as substance P and neurotensin, which also influence dopaminergic neurotransmission (and are proposed to be associated with MS), may deserve study in future.