Genetic variation in angiotensin converting-enzyme affects the white matter integrity and cognitive function of amnestic mild cognitive impairment patients

Association Between Angiotensin-Converting Enzyme (ACE) Gene Insertion/Deletion (I/D) Polymorphism Genotypes With Brain Volume and Hypertension in Alzheimer's Disease-A Retrospective Study

This study investigates the role of the ACE I/D polymorphism in Alzheimer's disease (AD) patients, particularly in relation to hypertension and its influence on brain volume. Seventy-seven AD patients, diagnosed based on Aging and Alzheimer's Association criteria, were enrolled from the Kaohsiung Municipal Ta-Tung Hospital Dementia Cohort. ACE I/D genotypes were identified through polymerase chain reaction, and various factors such as age, sex, education, brain volume, and neuropsychological test scores were analyzed. The results indicated that ACE genotypes, presence of apolipoprotein epsilon 4 (APOEε4), and brain volume did not significantly differ between patients with and without hypertension. While age and sex were associated with gray matter volume, cerebrospinal fluid volume correlated with age, sex, and hypertension. Total cranial volume was linked to sex, and the cerebrospinal fluid-to-total intracranial volume ratio was influenced by sex and education. Overall, ACE I/D genotypes and APOEε4 did not have a significant impact on brain volume in AD patients, regardless of hypertension status. Instead, brain atrophy was associated with sex, age, education, and hypertension. These findings suggest that although ACE may not significantly influence brain volume in AD patients, further large-scale studies are needed to clarify its role in AD pathogenesis.

Sarcopenia as a Risk Factor for Alzheimer's Disease: Genetic and Epigenetic Perspectives

Sarcopenia, defined as the age-associated loss of muscle mass and increased fragility with age, is increasing worldwide. The condition often precedes the development of Alzheimer's disease, thereby decreasing the levels of mobility and physical activity in those affected. Indeed, the loss of muscle mass has, in some studies, been associated with an increased risk of Alzheimer's disease and other dementias. However, a detailed understanding of the interplay between both conditions is not available and needs to be thoroughly addressed. In the following review, we focus on several genes, specifically APOE, BDNF, ACE, FTO, and FNDC5, that have been associated with both conditions. We also discuss the epigenetic regulation of each of these genes along with non-coding RNAs (ncRNAs) that may have a role in the development of both the sarcopenic and Alzheimer's disease phenotypes. Finally, we assert that the application of systems biology will unravel the relationship between sarcopenia and Alzheimer's disease and believe that the prevention of muscle loss in older age will reduce the incidence of debilitating cognitive decline.

Identification of novel diagnostic panel for mild cognitive impairment and Alzheimer's disease: findings based on urine proteomics and machine learning

BACKGROUND

Alzheimer's disease is a prevalent disease with a heavy global burden. Proteomics is the systematic study of proteins and peptides to provide comprehensive descriptions. Aiming to obtain a more accurate and convenient clinical diagnosis, researchers are working for better biomarkers. Urine is more convenient which could reflect the change of disease at an earlier stage. Thus, we conducted a cross-sectional study to investigate novel diagnostic panels.

METHODS

We firstly enrolled participants from China-Japan Friendship Hospital from April 2022 to November 2022, collected urine samples, and conducted an LC-MS/MS analysis. In parallel, clinical data were collected, and clinical examinations were performed. After statistical and bioinformatics analyses, significant risk factors and differential urinary proteins were determined. We attempt to investigate diagnostic panels based on machine learning including LASSO and SVM.

RESULTS

Fifty-seven AD patients, 43 MCI patients, and 62 CN subjects were enrolled. A total of 3366 proteins were identified, and 608 urine proteins were finally included in the analysis. There were 33 significantly differential proteins between the AD and CN groups and 15 significantly differential proteins between the MCI and CN groups. AD diagnostic panel included DDC, CTSC, EHD4, GSTA3, SLC44A4, GNS, GSTA1, ANXA4, PLD3, CTSH, HP, RPS3, CPVL, age, and APOE ε4 with an AUC of 0.9989 in the training test and 0.8824 in the test set while MCI diagnostic panel included TUBB, SUCLG2, PROCR, TCP1, ACE, FLOT2, EHD4, PROZ, C9, SERPINA3, age, and APOE ε4 with an AUC of 0.9985 in the training test and 0.8143 in the test set. Besides, diagnostic proteins were weakly correlated with cognitive functions.

CONCLUSIONS

In conclusion, the procedure is convenient, non-invasive, and useful for diagnosis, which could assist physicians in differentiating AD and MCI from CN.

POLYMORPHISM OF ACE AND AT2R1 GENES AS A GENETIC BACKGROUND FOR DIFFERENT TYPES OF ENCEPHALOPATHIES

OBJECTIVE

The aim: To study the prevalence of ACE I/D and AT2R1 A1166C gene polymorphisms in patients with CTE, SVD, AIE, and PIE and to assess the influence of the presence of a particular genotype of the studied genes on the occurrence and/or progression of encephalopathies.

PATIENTS AND METHODS

Materials and methods: A total of 96 patients with encephalopathies of various genesis (chronic traumatic encephalopathy (CTE) n=26; chronic alcohol-induced encephalopathy (AIE) n=26; microvascular ischemic disease of the brain (or cerebral small vessel disease, (SVD)) n=18; post-infectious encephalopathy (PIE) n=26) were involved in the study. The molecular genetic study was performed in the molecular genetics laboratory of the State Institution «Reference Center for Molecular Diagnostics of the Ministry of Health of Ukraine», Kyiv. Statistical processing of the results was performed using the STATISTICA 10.0 program.

RESULTS

Results: In patients with various types of encephalopathies, probable changes in the frequency distribution of genotypes of polymorphic variants I/D of the ACE gene were established (11.11% vs. 33.33% - carriers of the I/I genotype, 27.78% vs. 50.00% - carriers of the I/D genotype and 61.11% vs. 16.67% - carriers of the D/D genotype) and A1166C of the AT2R1 gene (22.22% vs. 66.67% - carriers of the A/A genotype, 50.00% vs. 25.00% - carriers A/C genotype, 27.78% versus 8.33% - carriers of the C/C genotype) compared to individuals of the control group only in patients with SVD. The presence of the D allele and the D/D genotype of the ACE gene is associated with a statistically significant increase in the risk of SVD development and progression (respectively, 4.2 times (95% CI (1.39-12.72)) and 7.9 (95% CI ( 1.31-47.05)) times). A similar trend was established for the carrier of the C allele of the A1166C polymorphic variant of the AT2R1 gene in patients with SVD: a 4.3-fold increase in the risk of development and progression (95% CI (1.30-13.86). In addition, there is a probable dependence between carrier genotype A/C of the AT2R1 gene and increased risk of PIE and AIE by 4.8 and 5.7 times, respectively.

CONCLUSION

Conclusions: Therefore, results suggest the reasonability to include the I/D of the ACE gene polymorphism investigation in the genetic panel of encephalopathies.

The new mechanism of cognitive decline induced by hypertension: High homocysteine-mediated aberrant DNA methylation

The prevalence and severity of hypertension-induced cognitive impairment increase with the prolonging of hypertension. The mechanisms of cognitive impairment induced by hypertension primarily include cerebral blood flow perfusion imbalance, white and gray matter injury with blood-brain barrier disruption, neuroinflammation and amyloid-beta deposition, genetic polymorphisms and variants, and instability of blood pressure. High homocysteine (HHcy) is an independent risk factor for hypertension that also increases the risk of developing early cognitive impairment. Homocysteine (Hcy) levels increase in patients with cognitive impairment induced by hypertension. This review summarizes a new mechanism whereby HHcy-mediated aberrant DNA methylation and exacerbate hypertension. It involves changes in Hcy-dependent DNA methylation products, such as methionine adenosyltransferase, DNA methyltransferases, S-adenosylmethionine, S-adenosylhomocysteine, and methylenetetrahydrofolate reductase (MTHFR). The mechanism also involves DNA methylation changes in the genes of hypertension patients, such as brain-derived neurotrophic factor, apolipoprotein E4, and estrogen receptor alpha, which contribute to learning, memory, and attention deficits. Studies have shown that methionine (Met) induces hypertension in mice. Moreover, DNA hypermethylation leads to cognitive behavioral changes alongside oligodendroglial and/or myelin deficits in Met-induced mice. Taken together, these studies demonstrate that DNA methylation regulates cognitive dysfunction in patients with hypertension. A better understanding of the function and mechanism underlying the effect of Hcy-dependent DNA methylation on hypertension-induced cognitive impairment will be valuable for early diagnosis, interventions, and prevention of further cognitive defects induced by hypertension.

Effects of quetiapine on behavioral changes and expression of myelin proteins in a chronic alcohol dependence rat model

BACKGROUND

As an atypical antipsychotic drug, quetiapine had been approved for bipolar disorder and for adjunctive therapy in major depressive disorder and schizophrenia. Recently quetiapine has been suggested to be a promising pharmacotherapy for alcohol dependence. This study was performed to determine the effects of quetiapine in rats chronically exposed to ethanol.

METHODS

Rats were exposed to ethanol solution (10 %; v/v) for 6 weeks. Saline or one of three doses of quetiapine (10, 20 or 40 mg/kg/day) was given by oral gavage while ethanol exposure for the next 14 weeks. Performance of learning and memory and withdrawal signs were evaluated. Then immunohistochemistry, western blot, quantitative real-time-PCR and transmission electron microscopy were performed to determine the effects of quetiapine on alterations of brain white matter markers (myelin basic protein, MBP; proteolipid protein, PLP) and morphology caused by chronic ethanol exposure.

RESULTS

Quetiapine treatment significantly alleviated withdrawal signs in the ethanol exposed rats. Chronic ethanol exposure reduced Y-type electric maze scores and the protein/mRNA expression levels of MBP and PLP in the prefrontal cortex and hippocampus, and these effects were reversed by quetiapine treatment. Similar ultrastructure morphological changes were observed.

CONCLUSIONS

Chronic quetiapine treatment alleviated the damage induced by chronic ethanol exposure with regard to learning and memory ability and to brain white matter. Thus, quetiapine appears to be a potentially promising pharmacotherapy for the treatment of alcohol use disorder.

ACE activity in blood and brain axis in an animal model for schizophrenia: Effects of dopaminergic manipulation with antipsychotics and psychostimulants

Objectives: Angiotensin I-converting enzyme (ACE) was initially correlated with schizophrenia (SCZ) in studies showing a correlation of ACE increased enzyme activity with memory impairments. Possible role for ACE in SCZ was also suggested by ACE activity interaction with dopaminergic mechanisms to modulate abnormalities of sensorimotor gating. In addition, we have demonstrated higher ACE activity in blood of SCZ subjects, its implication in cognitive performance in SCZ and its power as a predictor for SCZ diagnosis.Methods: ACE activity was determined in the serum and in selected brain regions of an animal model presenting SCZ-like behaviour, before and after the treatment with typical and atypical antipsychotics, and also in the serum of animals receiving the psychostimulants amphetamine/lisdexamphetamine.Results: Dopaminergic manipulations with antipsychotics and psychostimulants influenced the ACE activity, but with no correlation with the animal blood pressure.Conclusions: The validity of measuring ACE activity in animal blood to predict activity in the CNS, as well as the lack of correlation between the activity and blood pressure, before and after the treatment with antipsychotics, were confirmed here. Correlations of the present findings with data from clinical studies also strengthen the value of this animal model for studying several aspects of SCZ.

Potential Fluid Biomarkers for the Diagnosis of Mild Cognitive Impairment

Mild cognitive impairment (MCI) is characterized by a level of cognitive impairment that is lower than normal for a person’s age, but a higher function than that that observed in a demented person. MCI represents a transitional state between normal aging and dementia disorders, especially Alzheimer’s disease (AD). Much effort has been made towards determining the prognosis of a person with MCI who will convert to AD. It is now clear that cerebrospinal fluid (CSF) levels of Aβ40, Aβ42, total tau and phosphorylated tau are useful for predicting the risk of progression from MCI to AD. This review highlights the advantages of the current blood-based biomarkers in MCI, and discusses some of these challenges, with an emphasis on recent studies to provide an overview of the current state of MCI.