Angiotensin-converting enzyme insertion/deletion polymorphism is not a major determining factor in the development of sporadic Alzheimer disease: evidence from an updated meta-analysis

Utilizing Proteomic Approaches to Uncover the Neuroprotective Effects of ACE Inhibitors: Implications for Alzheimer's Disease Treatment

Two types of angiotensin-converting enzyme (ACE) inhibitors, lisinopril and benazepril HCl, were tested in neuroblastoma cells and found to upregulate low-density lipoprotein-receptor-related protein 1B (LRP1B) and 14-3-3 protein zeta/delta. Additionally, benazepril HCl was found to increase the expression of calreticulin. The upregulation of these proteins by ACE inhibitors may contribute to the amelioration of cognitive deficits in Alzheimer's disease/dementia, as well as the clinically observed deceleration of functional decline in Alzheimer's patients. This discovery suggests that the supplementation of ACE inhibitors may promote neuronal cell survival independently of their antihypertensive effect. Overall, these findings indicate that ACE inhibitors may be a promising avenue for developing effective treatments for Alzheimer's disease.

Angiotensin-converting enzyme polymorphisms AND Alzheimer's disease susceptibility: An updated meta-analysis

Background

Many studies among different ethnic populations suggested that angiotensin converting enzyme (ACE) gene polymorphisms were associated with susceptibility to Alzheimer’s disease (AD). However, the results remained inconclusive. In the present meta-analysis, we aimed to clarify the effect of ACE polymorphisms on AD risk using all available relevant data.

Methods

Systemic literature searches were performed using PubMed, Embase, Alzgene and China National Knowledge Infrastructure (CNKI). Relevant data were abstracted according to predefined criteria.

Results

Totally, 82 independent cohorts from 65 studies were included, focusing on five candidate polymorphisms. For rs1799752 polymorphism, in overall analyses, the insertion (I) allele conferred increased risk to AD compared to the deletion (D) allele (I vs. D: OR = 1.091, 95% CI = 1.007–1.181, p = 0.032); while the I carriers showed increased AD susceptibility compared with the D homozygotes (II + ID vs. DD: OR = 1.131, 95% CI = 1.008–1.270, p = 0.036). However, none of the positive results passed FDR adjustment. In subgroup analysis restricted to late-onset individuals, the associations between rs1799752 polymorphism and AD risk were identified using allelic comparison (OR = 1.154, 95% CI = 1.028–1.295, p = 0.015, FDR = 0.020), homozygotes comparison, dominant model and recessive model (II vs. ID + DD: OR = 1.272, 95% CI = 1.120–1.444, p < 0.001, FDR < 0.001). Nevertheless, no significant association could be revealed after excluding studies not in accordance with Hardy-Weinberg equilibrium (HWE). In North Europeans, but not in East Asians, the I allele demonstrated increased AD susceptibility compared to the D allele (OR = 1.096, 95% CI = 1.021–1.178, p = 0.012, FDR = 0.039). After excluding HWE-deviated cohorts, significant associations were also revealed under homozygotes comparison, additive model (ID vs. DD: OR = 1.266, 95% CI = 1.045–1.534, p = 0.016, FDR = 0.024) and dominant model (II + ID vs. DD: OR = 1.197, 95% CI = 1.062–1.350, p = 0.003, FDR = 0.018) in North Europeans. With regard to rs1800764 polymorphism, significant associations were identified particularly in subgroup of European descent under allelic comparison (T vs. C: OR = 1.063, 95% CI = 1.008–1.120, p = 0.023, FDR = 0.046), additive model and dominant model (TT + TC vs. CC: OR = 1.116, 95% CI = 1.018–1.222, p = 0.019, FDR = 0.046). But after excluding studies not satisfying HWE, all these associations disappeared. No significant associations were detected for rs4343, rs4291 and rs4309 polymorphisms in any genetic model.

Conclusions

Our results suggested the significant but modest associations between rs1799752 polymorphism and risk to AD in North Europeans. While rs4343, rs4291 and rs4309 polymorphisms are unlikely to be major factors in AD development in our research.

Genetic factors associated with the predisposition to late onset Alzheimer's disease

BACKGROUND

Alzheimer's disease is a progressive, irreversible neurodegenerative disorder characterized by loss of memory and cognitive skills. More than 90% of cases are sporadic and have later age of onset. Many studies have shown a genetic predisposition for late onset Alzheimer's disease (LOAD). The most studied genetic predisposition factor is apolipoprotein E gene besides other susceptibility genes involved in vascular pathologies, homocysteine metabolism, and neuronal growth and differentiation such as methylenetetrahydrofolate reductase (MTHFR), angiotensin-converting enzyme (ACE), APOB and brain derived neurotrophic factor (BDNF).

METHODS

In this study Factor V Leiden (G1691A) and H1299R, prothrombin G20210A, Factor XIII V34L, B-fibrinogen -455G>A, PAI-1 5G/4G, HPA1 b/a, MTHFR C677T, MTHFR A1298C, APOE, ACE I/D, BDNF C270T and G196A polymorphisms were evaluated in 100 LOAD patients and 100 age matched healthy controls.

RESULTS

APOE4 allele, MTHFR CC^A1298C and BDNF TT^C270T genotypes were significantly higher in LOAD patients compared to the control group (p < 0.001, p = 0.04, p = 0.03, respectively). There were no significant associations between other genotypes and allele frequencies. Mini-Mental State Examination (MMSE) scores and age at onset of the patients were also evaluated for each and combined genotypes. Age at onset was significantly lowered by about approximately 4 and 5 years in patients carrying BDNF TT^C270T and MTHFR TT^C677T genotypes, respectively.

CONCLUSION

APOE, MTHFR A1298C and BDNF C270T polymorphisms may be associated with LOAD and BDNF and MTHFR alleles may play a role in the age at onset of the LOAD.

Association of mir-196a-2 rs11614913 and mir-149 rs2292832 Polymorphisms With Risk of Cancer: An Updated Meta-Analysis

Background: Accumulating evidence suggests that functional dysregulations of miRNAs, especially miR-196a-2 and miR-149, in cancers could be attributed to polymorphisms in miRNA sequences. This study was aimed at clarifying the association of mir-196a-2 rs11614913 and mir-149 rs2292832 with cancer risk by performing an updated meta-analysis of genetic association studies. Methods: PubMed, Embase, Scopus, and ScienceDirect databases were searched until 9 April 2018 to identify eligible studies. Studies should meet the following criteria to be included in the meta-analysis: evaluation of genetic association between rs11614913 and/or rs2292832 and susceptibility to cancer; A case-control design; Written in English; Availability of sufficient data for estimating odds ratio (OR) and its 95% confidence interval (95%CI). Studies that met the following criteria were excluded: review articles, meta-analysis, abstracts or conference papers; duplicate publications; studies on animals or cell-lines; studies without a case-control design; studies that did not report genotype frequencies. Pooled ORs and 95% CIs were estimated using a total of 111 studies (41,673 cases and 49,570 controls) for mir-196a rs11614913 and 44 studies (15,954 cases and 19,594 controls) for mir-149 rs2292832. Stratified analysis according to quality scores, genotyping method, ethnicity, broad cancer category and cancer type was also performed. Results: Mir-196a-2 rs11614913 T allele was associated with decreased cancer risk in overall population. The association was only significant in Asians but not Caucasians. In subgroup analysis, significant associations were found in high quality studies, gynecological cancers, ovarian, breast, and hepatocellular cancer. Mir-149 rs2292832 was not associated with cancer risk in overall population and there were no differences between Asians and Caucasians. However, the T allele was associated with a decrease risk of gastrointestinal tract cancers under the heterozygote model and an increased risk of colorectal cancer under the recessive model. Conclusions: The present meta-analysis suggests that mir-196a-2 rs11614913 may contribute to the risk of cancer especially in Asians. Mir-149 rs2292832 may modulate the risk of gastrointestinal tract cancers especially colorectal cancer. This study had some limitations such as significant heterogeneity in most contrasts, limited number of studies enrolling Africans or Caucasians ancestry and lack of adjustment for covariates and environmental interactions.

Genetic meta-analysis of diagnosed Alzheimer's disease identifies new risk loci and implicates Aβ, tau, immunity and lipid processing

Risk for late-onset Alzheimer's disease (LOAD), the most prevalent dementia, is partially driven by genetics. To identify LOAD risk loci, we performed a large genome-wide association meta-analysis of clinically diagnosed LOAD (94,437 individuals). We confirm 20 previous LOAD risk loci and identify five new genome-wide loci (IQCK, ACE, ADAM10, ADAMTS1, and WWOX), two of which (ADAM10, ACE) were identified in a recent genome-wide association (GWAS)-by-familial-proxy of Alzheimer's or dementia. Fine-mapping of the human leukocyte antigen (HLA) region confirms the neurological and immune-mediated disease haplotype HLA-DR15 as a risk factor for LOAD. Pathway analysis implicates immunity, lipid metabolism, tau binding proteins, and amyloid precursor protein (APP) metabolism, showing that genetic variants affecting APP and Aβ processing are associated not only with early-onset autosomal dominant Alzheimer's disease but also with LOAD. Analyses of risk genes and pathways show enrichment for rare variants (P = 1.32 × 10-7), indicating that additional rare variants remain to be identified. We also identify important genetic correlations between LOAD and traits such as family history of dementia and education.

Arterial aging mediates the effect of TNF-α and ACE polymorphisms on mental health in elderly individuals: insights from IKARIA study

BACKGROUND

Aging is characterized by an insidious decline in cognitive function. Several genetic and lifestyle factors have been implicated in the increased risk or early onset of dementia.

AIM

We sought to assess the role of tumor necrosis factor (TNF) and angiotensin-converting enzyme (ACE) polymorphisms on the development of impaired mental health in respect to indices of arterial aging in nonagenarian individuals.

DESIGN

178 consecutive subjects above 75 years that permanently inhabit in the island of IKARIA, Greece were recruited.

METHODS

Aortic distensibility (AoD) was calculated and genetic evaluation was performed on the ACE Insertion/Deletion gene polymorphism (intron 16) and the G/A transition (position -308) of the TNF gene. Cognitive function was evaluated using the Mini-mental State Examination (MMSE).

RESULTS

The DD genotype for ACE was independently associated ( b  = -0.44, P = 0.007) with AD while AoD remained an independent determinant of mental status (OR = 1.82, P = 0.036). Interestingly though, when a combined genetic index (GI) was calculated for both genes (ACE and TNF), subjects being double homozygous (DD for ACE and GG for TNF) for these loci presented significantly decreased MMSE (adjusted OR = 0.259, P = 0.033). This GI independently associated with AD (beta coefficient = -0.785, P = 0.002). When AoD was included, GI lost its predictive role (OR = 0.784, P = 0.783) towards MMSE. AoD has marginal indirect mediating effect in the association of the GI with MMSE ( P = 0.07).

CONCLUSION

Vascular aging may modulates the genetic substrate of elderly subjects on the risk for developing dementia.

Association between dementia and vascular disease-associated polymorphisms in a Tunisian population

PURPOSE

Dementia is a multifactorial idiopathic pathology caused by clinical, eDementia is a multifactorial idiopathic pathology caused by clinical, environmental and genetic factors. Hence, its etiology is still unknown. We aimed to evaluate the association between five genetic risk factors for vascular diseases and dementia individually and when gathered in haplotypes.

MATERIALS AND METHOD

We enrolled 200 dementia patients and 300 controls. All subjects were genotyped for vascular diseaseassociated polymorphisms in the genes coding for Apolipoprotein-E (ApoE), angiotensin converting enzyme (ACE) and Paraoxonase-1 (PON1).

RESULTS

The association between dementia risk and all the studied polymorphisms except of PON1-Q192R was found to be significant. Carrying the ApoE e4 allele seems to increase dementia risk by 4.32 fold (p = 0.001). The risk associated with ACE I and PON1-L55M T alleles were lower (2.58 and 2.11 fold, p < 0.001 and p = 0.015, respectively). When combined in haplotypes, these polymorphisms showed a cumulative and synergetic effect. GTICC haplotype appears to be associated with 9-fold dementia risk (p < 0.001), whereas AADTT seems to reduce dementia risk by 80% (p = 0.003).

CONCLUSION

Our results suggest that, ApoE ε4, ACE I and PON1-L55M T alleles are associated with dementia risk whether these polymorphisms were studied separately or gathered in haplotypes. Still, the contribution of each gene to the pathophysiological development of dementia must be more investigated.

Clearance of cerebral Aβ in Alzheimer's disease: reassessing the role of microglia and monocytes

Deficiency in cerebral amyloid β-protein (Aβ) clearance is implicated in the pathogenesis of the common late-onset forms of Alzheimer’s disease (AD). Accumulation of misfolded Aβ in the brain is believed to be a net result of imbalance between its production and removal. This in turn may trigger neuroinflammation, progressive synaptic loss, and ultimately cognitive decline. Clearance of cerebral Aβ is a complex process mediated by various systems and cell types, including vascular transport across the blood–brain barrier, glymphatic drainage, and engulfment and degradation by resident microglia and infiltrating innate immune cells. Recent studies have highlighted a new, unexpected role for peripheral monocytes and macrophages in restricting cerebral Aβ fibrils, and possibly soluble oligomers. In AD transgenic (ADtg) mice, monocyte ablation or inhibition of their migration into the brain exacerbated Aβ pathology, while blood enrichment with monocytes and their increased recruitment to plaque lesion sites greatly diminished Aβ burden. Profound neuroprotective effects in ADtg mice were further achieved through increased cerebral recruitment of myelomonocytes overexpressing Aβ-degrading enzymes. This review summarizes the literature on cellular and molecular mechanisms of cerebral Aβ clearance with an emphasis on the role of peripheral monocytes and macrophages in Aβ removal.

Association between an angiotensin-converting enzyme gene polymorphism and Alzheimer's disease in a Tunisian population

BACKGROUND

The angiotensin-converting enzyme gene (ACE) insertion/deletion (I/D or indel) polymorphism has long been linked to Alzheimer's disease (AD), but the interpretation of established data remains controversial. The aim of this study was to determine whether the angiotensin-converting enzyme is associated with the risk of Alzheimer's disease in Tunisian patients.

METHODS

We analyzed the genotype and allele frequency distribution of the ACE I/D gene polymorphism in 60 Tunisian AD patients and 120 healthy controls.

RESULTS

There is a significantly increased risk of AD in carriers of the D/D genotype (51.67% in patients vs. 31.67% in controls; p = .008, OR = 2.32). The D allele was also more frequently found in patients compared with controls (71.67% vs. 56.25%; p = .003, OR = 2.0). Moreover, as assessed by the Mini-Mental State Examination, patient D/D carriers were more frequently found to score in the severe category of dementia (65%) as compared to the moderate category (32%) or mild category (3%).

CONCLUSIONS

The D/D genotype and D allele of the ACE I/D polymorphism were associated with an increased risk in the development of AD in a Tunisian population. Furthermore, at the time of patient evaluation (average age 75 years), patients suffering with severe dementia were found predominantly in D/D carriers and, conversely, the D/D genotype and D allele were more frequently found in AD patients with severe dementia. These preliminary exploratory results should be confirmed in larger studies and further work is required to explore and interpret possible alternative findings in diverse populations.

Association between ACE polymorphism, cognitive phenotype and APOE E4 allele in a Tunisian population with Alzheimer disease

Angiotensin-converting enzyme (ACE) has shown altered activity in patients with neurological diseases. An insertion/deletion (I/D) polymorphism of the ACE gene encoding angiotensin-converting enzyme has been reported to be associated with the risk for Alzheimer's disease (AD), and is generally considered to be a disorder primarily affecting memory. We conducted a case-control study in a sample composed of 85 sporadic AD patients and 90 age- and sex-matched controls to investigate the possible effect of the polymorphism and cognitive profile. Our data revealed an association between the ACE polymorphism and AD risk. There was a significant difference in the ACE allele or genotype frequencies between cases and controls. The D/D genotype showed an increased risk for AD and in the amnestic group and the effect was independent on ApoE genotypes.