Frontotemporal dementia presentation in patients with heterozygous p.H157Y variant of TREM2

BACKGROUND

The triggering receptor expressed on myeloid cell 2 (TREM2) is a major regulator of neuroinflammatory processes in neurodegeneration. To date, the p.H157Y variant of TREM2 has been reported only in patients with Alzheimer's disease. Here, we report three patients with frontotemporal dementia (FTD) from three unrelated families with heterozygous p.H157Y variant of TREM2: two patients from Colombian families (study 1) and a third Mexican origin case from the USA (study 2).

METHODS

To determine if the p.H157Y variant might be associated with a specific FTD presentation, we compared in each study the cases with age-matched, sex-matched and education-matched groups-a healthy control group (HC) and a group with FTD with neither TREM2 mutations nor family antecedents (Ng-FTD and Ng-FTD-MND).

RESULTS

The two Colombian cases presented with early behavioural changes, greater impairments in general cognition and executive function compared with both HC and Ng-FTD groups. These patients also exhibited brain atrophy in areas characteristic of FTD. Furthermore, TREM2 cases showed increased atrophy compared with Ng-FTD in frontal, temporal, parietal, precuneus, basal ganglia, parahippocampal/hippocampal and cerebellar regions. The Mexican case presented with FTD and motor neuron disease (MND), showing grey matter reduction in basal ganglia and thalamus, and extensive TDP-43 type B pathology.

CONCLUSION

In all TREM2 cases, multiple atrophy peaks overlapped with the maximum peaks of TREM2 gene expression in crucial brain regions including frontal, temporal, thalamic and basal ganglia areas. These results provide the first report of an FTD presentation potentially associated with the p.H157Y variant with exacerbated neurocognitive impairments.

Genetic overlap between cortical brain morphometry and frontotemporal dementia risk

Frontotemporal dementia (FTD) has a complex genetic etiology, where the precise mechanisms underlying the selective vulnerability of brain regions remain unknown. We leveraged summary-based data from genome-wide association studies (GWAS) and performed LD score regression to estimate pairwise genetic correlations between FTD risk and cortical brain imaging. Then, we isolated specific genomic loci with a shared etiology between FTD and brain structure. We also performed functional annotation, summary-data-based Mendelian randomization for eQTL using human peripheral blood and brain tissue data, and evaluated the gene expression in mice targeted brain regions to better understand the dynamics of the FTD candidate genes. Pairwise genetic correlation estimates between FTD and brain morphology measures were high but not statistically significant. We identified 5 brain regions with a strong genetic correlation (rg > 0.45) with FTD risk. Functional annotation identified 8 protein-coding genes. Building upon these findings, we show in a mouse model of FTD that cortical N-ethylmaleimide sensitive factor (NSF) expression decreases with age. Our results highlight the molecular and genetic overlap between brain morphology and higher risk for FTD, specifically for the right inferior parietal surface area and right medial orbitofrontal cortical thickness. In addition, our findings implicate NSF gene expression in the etiology of FTD.

Systematic Review: microRNAs as Potential Biomarkers in Mild Cognitive Impairment Diagnosis

The rate of progression from Mild Cognitive Impairment (MCI) to Alzheimer's disease (AD) is estimated at >10% per year, reaching up to 80-90% after 6 years. MCI is considered an indicator of early-stage AD. In this context, the diagnostic screening of MCI is crucial for detecting individuals at high risk of AD before they progress and manifest further severe symptoms. Typically, MCI has been determined using neuropsychological assessment tools such as the Montreal Cognitive Assessment (MoCA) or Mini-Mental Status Examination (MMSE). Unfortunately, other diagnostic methods are not available or are unable to identify MCI in its early stages. Therefore, identifying new biomarkers for MCI diagnosis and prognosis is a significant challenge. In this framework, miRNAs in serum, plasma, and other body fluids have emerged as a promising source of biomarkers for MCI and AD-related cognitive impairments. Interestingly, miRNAs can regulate several signaling pathways via multiple and diverse targets in response to pathophysiological stimuli. This systematic review aims to describe the current state of the art regarding AD-related target genes modulated by differentially expressed miRNAs in peripheral fluids samples in MCI subjects to identify potential miRNA biomarkers in the early stages of AD. We found 30 articles that described five miRNA expression profiles from peripheral fluid in MCI subjects, showing possible candidates for miRNA biomarkers that may be followed up as fluid biomarkers or therapeutic targets of early-stage AD. However, additional research is needed to validate these miRNAs and characterize the precise neuropathological mechanisms.

Cardiotoxic Effects of the Antineoplastic Doxorubicin in a Model of Metabolic Syndrome: Oxidative Stress and Transporter Expression in the Heart

ABSTRACT

The aim of the present work was to examine whether metabolic syndrome-like conditions in rats with fructose (F) overload modify the cardiotoxic effects induced by doxorubicin (DOX) and whether the treatment altered the expression of P-gp, breast cancer resistance protein, and organic cation/carnitine transporters in the heart. Male Sprague-Dawley rats received either tap water (control group [C]; n = 16) or water with F 10% wt/vol (n = 16) during 8 weeks. Three days before being killed, the animals received a single dose of DOX (6 mg/kg, ip, md) (C-DOX and F-DOX groups) or vehicle (VEH; ISS 1 mL/kg BW; ip) (C-VEH and F-VEH groups) (n = 8 per group). F overload enhanced thiobarbituric acid-reactive substance levels in the left ventricle, and DOX injection further increased those values. DOX did not alter thiobarbituric acid-reactive substance production in C animals. DOX caused a decrease of 30% in the ejection fraction and a nearly 40% reduction in the fractional shortening in F animals, but not in C rats. Cardiac tissue levels of P-gp decreased by about 30% in F rats compared with the C groups. DOX did not modify cardiac P-gp expression. Breast cancer resistance protein and organic cation/carnitine transporter (OCTN 1/2/3) protein levels did not change with either F or DOX. It is suggested that DOX could cause greater cardiotoxicity in rats receiving F, probably due to enhanced cardiac lipid peroxidation and lower expression of cardiac P-gp. These results support the hypothesis that the cardiotoxicity of DOX could be increased under metabolic syndrome-like conditions or in other health disorders that involve cardiovascular risk factors.

Dietary Phosphorus to Protein Ratio for the Mexican Population with Chronic Kidney Disease

OBJECTIVE

Hyperphosphatemia is a major contributor to poor outcomes among cases of chronic kidney disease. Considering that foods with high protein content are major sources of phosphorus, a more suitable dietary phosphorus measure is the phosphorus to protein ratio. However, Mexican phosphorus to protein ratio tables do not exist. This article aims to estimate the phosphorus to protein ratio in foods commonly used by the Mexican population and to establish its usefulness in the selection of foods for patients with chronic kidney disease.

METHODS

Six tables with the phosphorus to protein ratio were developed from different data sources concerning Mexican animal food composition.

RESULTS

Egg whites have the best phosphorus to protein ratio. Partially skimmed milk has the lowest ratio among dairy products. Dairy products have high phosphorus to protein ratio variability. Red meat products have a ratio with an average of 9 mg/g. The phosphorus to protein ratio varies considerably for seafood (1.2-38.3 mg/g).

CONCLUSIONS

The phosphorus to protein ratio could be a good strategy to choose each food during chronic kidney disease dietary treatment for the Mexican population.

Thyroid disorders and nitric oxide in cardiovascular adaptation to hypovolemia

This study aimed to investigate whether nitric oxide participates in the cardiovascular function and haemodynamic adaptation to acute haemorrhage in animals with thyroid disorders. Sprague-Dawley rats aged 2months old treated with T3 (hyper, 20μg/100g body weight) or 0.02% methimazole (hypo, w/v) during 28days were pre-treated with N(G) nitro-l-arginine methyl ester (L-NAME) and submitted to 20% blood loss. Heart function was evaluated by echocardiography. Measurements of arterial blood pressure, heart rate, nitric oxide synthase activity and protein levels were performed. We found that hypo decreased fractional shortening and ejection fraction and increased left ventricle internal diameter. Hyper decreased ventricle diameter and no changes in cardiac contractility. Haemorrhage elicited a hypotension of similar magnitude within 10min. Then, this parameter was stabilized at about 30-40min and maintained until finalized, 120min. L-NAME rats showed that the immediate hypotension would be independent of nitric oxide. Nitric oxide synthase inhibition blunted the changes of heart rate induced by blood loss. Hyper and hypo had lower atrial enzyme activity associated with a decreased enzyme isoform in hypo. In ventricle, hyper and hypo had a higher enzyme activity, which was not correlated with changes in protein levels. Haemorrhage induced an increased heart nitric oxide production. We concluded that thyroid disorders were associated with hypertrophic remodelling which impacted differently on cardiac function and its adaptation to a hypovolemia. Hypovolemia triggered a nitric oxide synthase activation modulating the heart function to maintain haemodynamic homeostasis. This involvement depends on a specific enzyme isoform, cardiac chamber and thyroid state.