Angiotensin-converting enzyme I/D gene polymorphism and risk of multiple sclerosis

Neuropsychiatric Properties of the ACE2/Ang-(1-7)/Mas Pathway: A Brief Review

The current pharmacological strategies for the management of anxiety disorders and depression, serious conditions which are gaining greater prevalence worldwide, depend on only two therapeutic classes of mood-stabilizing drugs: Serotonin Reuptake Inhibitors (SSRIs) and Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs). Although first line agents with proven efficacy, their clinical success in the management of anxiety disorders and depression is still considered highly complex due to the multifaceted nature of such conditions. Several studies have shown a possible therapeutic target could be found in the form of the Angiotensin-Converting Enzyme [ACE] type 2 (ACE2), Angiotensin [Ang]-(1-7) and Mas receptor pathway of the Renin- Angiotensin System (RAS), which as will be discussed, has been described to exhibit promising therapeutic properties for the management of anxiety disorders and depression. In this article, the literature to describe recent findings related to the role of the RAS in anxiety and depression disorders was briefly revised. The literature used covers a time range from 1988 to 2019 and were acquired from the National Center for Biotechnology Information's (NCBI) PubMed search engine. The results demonstrated in this review are promising and encourage the development of new research for the treatment of anxiety and depression disorders focusing on the RAS. In conclusion, the ACE2/Ang-(1-7)/Mas pathway may exhibit anxiolytic and anti-depressive effects through many possible biochemical mechanisms both centrally and peripherally, and result in highly promising mental health benefits which justifies further investigation into this system as a possible new therapeutic target in the management of neuropsychiatric disorders, including any as of yet undescribed risk-benefit analysis compared to currently-implemented pharmacological strategies.

Association between the ACE-I/D polymorphism and nicotine dependence amongst patients with lung cancer

The biologically active peptide angiotensin II is cleaved from angiotensinogen by the renin and the angiotensin-converting enzyme (ACE), an enzymatic cascade known as the renin-angiotensin system (RAS). RAS may be important in the etiology of nicotine dependence by influencing dopaminergic signaling. In the present study, the association between an insertion/deletion (I/D) polymorphism of ACE and nicotine dependence amongst patients with lung cancer was assessed. To date, several studies have shown the relevance of this polymorphic variant in both nicotine dependence and lung cancer. However, the present study is the first to address the potential role of the ACE-I/D polymorphism in nicotine dependence among patients with lung cancer. Genotyping was performed in 305 patients with lung cancer (males/females, 214/91). Significantly more male smokers had the ACE-I allele compared with male non-smokers (44.9 vs. 20.0%; P<0.05). The risk of smoking was ~5-fold higher for males with the ACE-I allele (ACE-II homozygous and ACE-ID heterozygous) vs. ACE-DD homozygous (odds ratio, 5.47; 95% confidence interval, 1.4-21.9; P=0.016). The pack-year smoking history in a subgroup of females with squamous cell carcinoma carrying the ACE-I allele was significantly lower compared with ACE-DD (37.1±14.1 vs. 57.0±29.1; F=4.5; P=0.046). The ACE-I/D polymorphism accounted for 17.6% of the smoking severity in this patient group (β, -0.42; multiple R² change, 0.176; P=0.046). These results suggest that the ACE-I/D polymorphism contributes to the risk of nicotine dependence and smoking severity in lung cancer patients in a sex-specific manner.

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.

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.

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.

Modulation of the kallikrein/kinin system by the angiotensin-converting enzyme inhibitor alleviates experimental autoimmune encephalomyelitis

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system (CNS). Bradykinin is the end-product of the kallikrein/kinin system, which has been recognized as an endogenous target for combating CNS inflammation. Angiotensin-converting enzyme (ACE) inhibitors influence the kallikrein/kinin system and reportedly have immunomodulatory characteristics. The objectives of this study were to determine whether bradykinin is involved in the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of MS, and whether bradykinin control by the ACE inhibitor could be a therapeutic target in MS. The ACE inhibitor enalapril (1·0 or 0·2 mg/kg/day) was administered orally to EAE mice and the serum levels of bradykinin and cytokines in EAE mice were analysed. As a result, the administration of enalapril increased serum bradykinin levels, decreased the clinical and pathological severity of EAE and attenuated interleukin-17-positive cell invasion into the CNS. Additionally, bradykinin receptor antagonist administration reduced the favourable effects of enalapril. Our results suggest that bradykinin is involved in the pathomechanism underlying CNS inflammation in EAE, possibly through inhibiting cell migration into CNS. Control of the kallikrein/kinin system using ACE inhibitors could be a potential therapeutic strategy in MS.

Treatment with angiotensin II receptor blockers is associated with prolonged relapse-free survival, lower relapse rate, and corticosteroid-sparing effect in patients with giant cell arteritis

OBJECTIVE

To determine whether concomitant treatment with angiotensin-converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) is associated with changes in the outcome of patients with giant cell arteritis (GCA).

METHODS

A study cohort of 106 patients with biopsy-proven GCA was longitudinally followed up for 7.8 ± 3.3 years. Patients were stratified according to their treatment with ACEI, ARB, or no ACEI/ARB. Time to first relapse, number of flares, time to achieve a stable prednisone dose <10mg/day and <5mg/day with no relapses, time required to completely discontinue prednisone, cumulative dose of prednisone received during the first year, and concentrations of acute-phase reactants at pre-defined time points (baseline, 6, 12, 18, and 24 months) were compared among the 3 groups. Cox proportional hazards models were performed to adjust for potential confounders.

RESULTS

Patients receiving ARB presented a significantly longer relapse-free survival than patients treated with ACEI or patients not receiving ACEI/ARB (p = 0.02). The adjusted hazard ratio for relapses in patients treated with ARB was 0.32 (95% CI: 0.12-0.81, p = 0.017). In addition, patients who received ARB achieved a prednisone maintenance dose <10mg/day faster than all other patients (p = 0.0002). No significant differences were observed among groups in acute-phase reactant levels during follow-up. However, patients not receiving ACEI/ARB had significantly higher C-reactive protein and haptoglobin concentrations than those receiving ACEI or ARB at various time points.

CONCLUSIONS

Addition of ARB to glucocorticoids is associated with lower relapse rate and more prolonged disease-free survival in patients with GCA.

Blocking angiotensin-converting enzyme induces potent regulatory T cells and modulates TH1- and TH17-mediated autoimmunity

The renin-angiotensin-aldosterone system (RAAS) is a major regulator of blood pressure. The octapeptide angiotensin II (AII) is proteolytically processed from the decapeptide AI by angiotensin-converting enzyme (ACE), and then acts via angiotensin type 1 and type 2 receptors (AT1R and AT2R). Inhibitors of ACE and antagonists of the AT1R are used in the treatment of hypertension, myocardial infarction, and stroke. We now show that the RAAS also plays a major role in autoimmunity, exemplified by multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). Using proteomics, we observed that RAAS is up-regulated in brain lesions of MS. AT1R was induced in myelin-specific CD4+ T cells and monocytes during autoimmune neuroinflammation. Blocking AII production with ACE inhibitors or inhibiting AII signaling with AT1R blockers suppressed autoreactive TH1 and TH17 cells and promoted antigen-specific CD4+FoxP3+ regulatory T cells (Treg cells) with inhibition of the canonical NF-kappaB1 transcription factor complex and activation of the alternative NF-kappaB2 pathway. Treatment with ACE inhibitors induces abundant CD4+FoxP3+ T cells with sufficient potency to reverse paralytic EAE. Modulation of the RAAS with inexpensive, safe pharmaceuticals used by millions worldwide is an attractive therapeutic strategy for application to human autoimmune diseases.

Optimizing Outcomes in Multiple Sclerosis – A Consensus Initiative

Background

Initiation of immunomodulators in patients experiencing a clinically isolated syndrome (CIS) may delay progression to clinically definite MS. However, lack of consensus remains on many issues affecting optimal management of MS.

Method

A panel of 21 MS experts met during 9 meetings to explore key issues in MS and CIS. Meetings addressed 3 phases: 1. CIS definition and diagnosis; 2. initial therapy; and 3. monitoring disease progression and treatment efficacy. Newsletters covering each phase were sent to 5000 U.S.-based neurologists who were invited to participate in an online survey on key issues.

Results

Most panel members agreed that early treatment may minimize neurodegeneration and most would recommend it for patients; that a dose-response relationship exists for beta-interferon therapy; that more aggressive therapy was most effective early in the disease course; and, that MRI has a role in monitoring disease progression. In face of suboptimal response, most would switch patients to a different therapy; while combination therapy would be reserved for those failing monotherapy regimes. Most online survey respondents agreed with these positions.

Conclusions

There was uniform consensus from this panel of MS experts that early initiation of immunomodulator therapy was beneficial for CIS patients.

Multiple sclerosis genetics

Multiple sclerosis (MS) clusters with the so-called complex genetic diseases, a group of common disorders characterized by modest disease risk heritability and multifaceted gene-environment interactions. The major histocompatibility complex (MHC) is the only genomic region consistently associated with MS, and susceptible MHC haplotypes have been identified. Although the MHC does not account for all genetic contribution to MS, the other genetic contributors have been elusive. Microarray gene-expression studies, which also have not identified a major MS locus, have, however, been promising in elucidating some of the possible pathways involved in the disease. Yet, microarray studies thus far have been unable to separate the genetic causes of MS from the expression consequences of MS. The use of new methodologies and technologies to refine the phenotype, such as brain spectroscopy, PET and functional magnetic resonance imaging combined with novel computational tools and a better understanding of the human genome architecture, may help resolve the genetic causes of MS.

Roles of the kallikrein/kinin system in the adaptive immune system

This review deals with the effects of kinins, a family of octa- to decapeptides structurally related to bradykinin (BK), in adaptive immune responses. Herein, we discuss the experimental evidence that kinins may exert influence on multiple players of the immune system (i.e. macrophages, dendritic cells, T and B lymphocytes), and modulate the activation, proliferation, migration and effector functions of these cells. We also give an overview of the possible impact of kinins in human autoimmune diseases and corresponding animal models, with special emphasis on autoimmune neuroinflammation and arthritis. These studies indicate a possible immunomodulatory capacity of kinins beyond our current knowledge of kinin actions regarding the vascular system, and thus the way towards future therapeutic approaches.