A proteomics study reveals a predominant change in MaoB expression in platelets of healthy volunteers after high protein meat diet: relationship to the methylation cycle

The plasma proteome is favorably modified by a high protein diet but not by additional resistance training in older adults: A 17-week randomized controlled trial

Background

The age-related loss of muscle mass significantly contributes to the development of chronic diseases, loss of mobility and dependency on others, yet could be improved by an optimized lifestyle.

Objective

The goal of this randomized controlled trial was to compare the influence of a habitual diet (CON) with either a diet containing the recommended protein intake (RP) or a high protein intake (HP), both with and without strength training, on the plasma proteome in older adults.

Methods

One hundred and thirty-six women and men (65–85 years) were randomly assigned to three intervention groups. CON continued their habitual diet; participants of the HP and RP group consumed either high protein or standard foods. After 6 weeks of dietary intervention, HP and RP groups additionally started a strength training intervention twice per week for 8 weeks. Twenty-four hours dietary recalls were performed every 7–10 days. Body composition was assessed and blood taken. Plasma proteomics were assessed with LC-MS.

Results

Participants of the HP group doubled their baseline protein intake from 0.80 ± 0.31 to 1.63 ± 0.36 g/kg BW/d; RP increased protein intake from 0.89 ± 0.28 to 1.06 ± 0.26 g/kg BW/d. The CON group kept the protein intake stable throughout the study. Combined exercise and HP initiated notable changes, resulting in a reduction in bodyfat and increased muscle mass. Proteomics analyses revealed 14 significantly affected proteins by HP diet, regulating innate immune system, lipid transport and blood coagulation, yet the additional strength training did not elicit further changes.

Conclusions

Combined HP and resistance exercise in healthy older adults seem to induce favorable changes in the body composition. Changes in the plasma proteome due to the high protein diet point to a beneficial impact for the innate immune system, lipid transport and blood coagulation system, all of which are involved in chronic disease development.

Clinical trial registration

The study was registered at ClinicalTrials.gov (NCT04023513).

Healthy diet, depression and quality of life: A narrative review of biological mechanisms and primary prevention opportunities

Unipolar depressive disorder (UDD) affects more than 264 million people worldwide and was projected well before the severe acute respiratory syndrome coronavirus 2 pandemic to be the leading cause of disability-adjusted life years lost in 2030. It is imperative for leading economies to implement preventive strategies targeted towards UDD, given consistent policies are currently lacking. Recently established similarities between the aetiological hypotheses of depression and cardiometabolic diseases are shifting paradigms within this field. It is believed that dietary practices could potentially reduce the incidence of depression; similar to their effects on metabolism. Thus, the aim of this review was to compile current evidence on healthy dietary patterns as suitable contributors towards primary prevention strategies against UDD. Most of the well-known biological mechanisms behind depression have been positively associated with healthful diets and dietary patterns to varying degrees. Interestingly, a common factor of UDD is the production and overall effects of inflammatory cytokines, such as interleukin-6, tumor necrosis factor-α, and C-reactive protein. These compounds have been associated with depressive symptoms, disturbances in neuroendocrine function, leaky gut, monoamine activity and brain function, while also being key factors in the development of cardiometabolic diseases. The Mediterranean diet (MD) in particular, is well supported by first-level evidence regarding its preventive qualities against metabolic and cardiovascular diseases and thus considered a model for healthy eating by various organizations. In one of the few clinical trials investigating these associations, the PREDIMED trial, individuals with diabetes assigned to a MD supplemented with mixed tree nuts experienced a 41% relative risk reduction for developing depression. Lastly, there is a need to include health related quality of life as an indicator of physical and mental well-being, considering its putative associations with depression and suicide risk. Going forward, focusing on clinical trials, using precise nutritional assessments, and identifying nutritional biomarkers which may be related to depression are needed to fully support the implementation of dietary recommendations in the field of psychiatry.

The impact of dietary macronutrient intake on cognitive function and the brain

Macronutrients - carbohydrates, fats, and proteins - supply the nutrients required for optimal functioning. Inadequate intake compromises both physical and brain health. We synthesized research on macronutrients from whole meals on cognitive function in healthy adults and identified underlying mechanisms. Intake of simple carbohydrates ('sugars') is consistently associated with decreased global cognition whereas consumption of complex carbohydrates correlates with successful brain aging and improved memory both in the short- and long-term. Saturated fatty acid intake correlates with decreased memory and learning scores whereas omega-3 intake correlates positively with memory scores. Protein intake boosts executive function and working memory when task-demands are high. Individual differences affecting the macronutrient-cognition relationship are age, physical activity, and glucose metabolism. Neural correlates reflect findings on cognitive functions: cortical thickness and cerebral amyloid burden correlate with sugar intake, inflammatory status and cerebral glucose metabolism correlate with fatty acid intake. Key mechanisms by which dietary macronutrients affect the brain and cognition include glucose and insulin metabolism, neurotransmitter actions, and cerebral oxidation and inflammation. In conclusion, macronutrient intake affects cognitive function both acutely and in the long-term, involving peripheral and central mechanisms. A healthy diet supports brain integrity and functionality, whereas inadequate nutrition compromises it. Studying diet can be key to nutritional recommendations, thereby improving the landscape of mental health and healthy brain aging.

Relationships of Cerebrospinal Fluid Alzheimer's Disease Biomarkers and COMT, DBH, and MAOB Single Nucleotide Polymorphisms

The noradrenergic and dopaminergic systems are affected in Alzheimer’s disease (AD). Polymorphisms in genes encoding enzymes and proteins that are components of these systems can affect products of transcription and translation and lead to altered enzymatic activity and alterations in overall dopamine and noradrenaline levels. Catechol-O-methyltransferase (COMT) and monoamine oxidase B (MAOB) are the enzymes that regulate degradation of dopamine, while dopamine β-hydroxylase (DBH) is involved in synthesis of noradrenaline. COMT Val158Met (rs4680), DBH rs1611115 (also called –1021C/T or –970C/T), and MAOB rs1799836 (also called A644G) polymorphisms have been previously associated with AD. We assessed whether these polymorphisms are associated with cerebrospinal fluid (CSF) AD biomarkers including total tau (t-tau), phosphorylated tau proteins (p-tau₁₈₁, p-tau₁₉₉, and p-tau₂₃₁), amyloid-β₄₂ (Aβ₄₂), and visinin-like protein 1 (VILIP-1) to test possible relationships of specific genotypes and pathological levels of CSF AD biomarkers. The study included 233 subjects: 115 AD, 53 mild cognitive impairment, 54 subjects with other primary causes of dementia, and 11 healthy controls. Significant decrease in Aβ₄₂ levels was found in patients with GG compared to AG COMT Val158Met genotype, while t-tau and p-tau₁₈₁ levels were increased in patients with AA compared to AG COMT Val158Met genotype. Aβ₄₂ levels were also decreased in carriers of A allele in MAO-B rs1799836 polymorphism, while p-tau₁₈₁ levels were increased in carriers of T allele in DBH rs1611115 polymorphism. These results indicate that COMT Val158Met, DBH rs1611115, and MAOB rs1799836 polymorphisms deserve further investigation as genetic markers of AD.

Proteomic signatures of antiplatelet drugs: new approaches to exploring drug effects

Antiplatelet agents represent the mainstay of acute coronary syndrome (ACS) therapy to prevent ischemic events and to improve safety in patients undergoing percutaneous coronary intervention. However, despite the availability of several drugs and the use of dual antiplatelet therapy, the pharmacological response is highly variable with a subset of patients continuing to experience recurrent thrombotic events, revealing a wide variability in platelet response to antiplatelet drugs. Several factors may explain this, including genetic variation and environmental factors. Here we look at the application of proteomic analysis, an approach that provides an integrated readout of these diverse influences.

Targeted mass spectrometry for the analysis of nutritive modulation of catalase and heme oxygenase-1 expression

Comprehensive physiological food assessment requires recording of activity profiles. To elucidate the nutritive regulation of antioxidant enzymes, a generally applicable targeted MS method was established for the expression analysis of catalase and then adapted to heme oxygenase-1. Before tryptic digestion, target proteins were prefractionated by off-gel IEF of stimulated and control cell lysate. Targeted proteome analysis was achieved by LC coupled with scheduled selected reaction monitoring MS using 2 proteotypic peptides per protein and 3-4 transitions per peptide. Relative quantification was performed by stable isotope labeling by amino acids in cell culture (SILAC). The assay showed good correlation with results by Western blot. Linearity, precision, and sensitivity were even improved (LC/SRM vs. Western blot: 3 vs. 1 orders of magnitude, RSD 3.7-13.7% vs. 18.4%, LOD 0.2 vs. 1.6μg/mL). The developed method indicated that coffee does not modulate catalase expression in macrophages (T7cat 103±22%, T17cat 103±16%, p>0.05 vs. control), but leads to a highly significant increase of heme oxygenase-1 expression (T15Ho-1 420±24%, T22Ho-1 364±37%, p<0.001 vs. control, p>0.05 T15Ho-1 vs. T22Ho-1). In regard to multiplex options of the method, targeted proteome analysis can be a valuable tool for the comprehensive analysis of cellular effects of food components.

BIOLOGICAL SIGNIFICANCE

In the present study, targeted mass spectrometry was applied to determine the influence of food components on the expression of antioxidative enzymes. The results implicate that targeted proteomics may develop into a valuable tool in food science and nutrition to determine the physiological effects of nutrients. In contrast to conventional methods for expression analysis, targeted proteome analysis can be applied to monitor the effects of a food component on a broad range of cellular targets in parallel. Additionally, proteins or protein modifications can be addressed which elude immunochemical methods.

A platelet protein biochip rapidly detects an Alzheimer's disease-specific phenotype

Alzheimer's disease (AD), a multifactorial neurodegenerative condition caused by genetic and environmental factors, is diagnosed using neuropsychological tests and brain imaging; molecular diagnostics are not routinely applied. Studies have identified AD-specific cerebrospinal fluid (CSF) biomarkers but sample collection requires invasive lumbar puncture. To identify AD-modulated proteins in easily accessible blood platelets, which share biochemical signatures with neurons, we compared platelet lysates from 62 AD, 24 amnestic mild cognitive impairment (aMCI), 13 vascular dementia (VaD), and 12 Parkinson's disease (PD) patients with those of 112 matched controls by fluorescence two-dimensional differential gel electrophoresis in independent discovery and verification sets. The optimal sum score of four mass spectrometry (MS)-identified proteins yielded a sensitivity of 94 % and a specificity of 89 % (AUC = 0.969, 95 % CI = 0.944-0.994) to differentiate AD patients from healthy controls. To bridge the gap between bench and bedside, we developed a high-throughput multiplex protein biochip with great potential for routine AD screening. For convenience and speed of application, this array combines loading control-assisted protein quantification of monoamine oxidase B and tropomyosin 1 with protein-based genotyping for single nucleotide polymorphisms (SNPs) in the apolipoprotein E and glutathione S-transferase omega 1 genes. Based on minimally invasive blood drawing, this innovative protein biochip enables identification of AD patients with an accuracy of 92 % in a single analytical step in less than 4 h.

Platelets, a reliable source for peripheral Alzheimer's disease biomarkers?

Peripheral biomarkers play an indispensable role in quick and reliable diagnoses of any kind of disease. With the population ageing, the number of people suffering from age-related diseases is expected to rise dramatically over the coming decades. In particular, all types of cognitive deficits, such as Alzheimer's disease, will increase. Alzheimer's disease is characterised mainly by coexistence of amyloid plaques and neurofibrillary tangles in brain. Reliable identification of such molecular characteristics antemortem, however, is problematic due to restricted availability of appropriate sample material and definitive diagnosis is only possible postmortem. Currently, the best molecular biomarkers available for antemortem diagnosis originate from cerebrospinal fluid. Though, this is not convenient for routine diagnosis because of the required invasive lumbar puncture. As a consequence, there is a growing demand for additional peripheral biomarkers in a more readily accessible sample material. Blood platelets, due to shared biochemical properties with neurons, can constitute an attractive alternative as discussed here. This review summarises potential platelet Alzheimer's disease biomarkers, their role, implication, and alteration in the disease. For easy comparison of their performance, the Hedge effect size was calculated whenever data were available.

PIPKIγ targets to the centrosome and restrains centriole duplication

Centriole biogenesis depends on the polo-like kinase (PLK4) and a small group of structural proteins. The spatiotemporal regulation of these proteins at pre-existing centrioles is essential to ensure that centriole duplication occurs once per cell cycle. Here, we report that phosphatidylinositol 4-phosphate 5-kinase type-1 gamma (PIP5K1C, hereafter referred to as PIPKIγ) plays an important role in centriole fidelity. PIPKIγ localized in a ring-like pattern in the intermediate pericentriolar materials around the proximal end of the centriole in G1, S and G2 phases, but not in M phase. This localization was dependent upon an association with centrosomal protein of 152 KDa (CEP152). Without detaining cells in S or M phase, the depletion of PIPKIγ led to centriole amplification in a manner that was dependent upon PLK4 and spindle assembly abnormal protein 6 homolog (SAS6). The expression of exogenous PIPKIγ reduced centriole amplification that occurred as a result of endogenous PIPKIγ depletion, hydroxyurea treatment or PLK4 overexpression, suggesting that PIPKIγ is likely to function at the PLK4 level to restrain centriole duplication. Importantly, we found that PIPKIγ bound to the cryptic polo-box domain of PLK4 and that this binding reduced the kinase activity of PLK4. Together, our findings suggest that PIPKIγ is a novel negative regulator of centriole duplication, which acts by modulating the homeostasis of PLK4 activity.

A combined proteomic and genetic analysis of the highly variable platelet proteome: from plasmatic proteins and SNPs

High biological variation in protein expression represents a major challenge in clinical proteomics. In a study based on 2D-DIGE, we found that the standardised abundance of only a few proteins varied by more than 50%. While some of the highest variable proteins in platelets of 52 healthy elderly were of plasmatic origin, such as albumin or haptoglobin, absence of several other high-abundant plasma proteins strongly suggests that plasma-derived proteins represent an integral part of the platelet proteome. Amongst the highly variable platelet-derived proteins, two spots were both identified as GSTO1 and assigned to either the wild-type or mutant isoform of SNP A140D. Remarkably, when the spots were considered within the respective genotype groups, their CV decreased to about the median variation. Albeit 2D-DIGE allowed correct genotyping, two individuals seemed to be GSTO1*A140 deficient. Probing 2D-Western blots with novel mAb, however, detected A140 protein as additional spot at pH 8.1, caused by the SNPs E155del and E208K. In contrast to previous studies, we show that GSTO1 protein is expressed in vivo, despite the deletion E155. Our data indicate that incorporation of exogenous proteins and genetic polymorphisms of endogenous proteins represent the main source of extreme biological variation in the platelet proteome.

The biometric measurement of alcohol consumption

BACKGROUND

Proper ascertainment of the history of alcohol consumption by an individual is an important component of medical diagnosis of disease and influences the implementation of appropriate treatment strategies that include prescription of medication, as well as intervention for the negative physical and social consequences of hazardous/harmful levels of alcohol consumption. Biological (biometric) diagnostic tests that provide information on current and past quantity and frequency of alcohol consumption by an individual, prior to onset of organ damage, continue to be sought.

METHODS

Platelet monoamine oxidase B (MAO-B) protein was quantitated in 2 populations of subjects who had histories of different levels of alcohol consumption. Levels were assayed by immunoblotting or by ELISA. The development and evaluation of the new ELISA-based measure of platelet MAO-B protein levels is described.

RESULTS

One subject population constituted a nontreatment-seeking, cross-sectional subject sample, and the other population was a longitudinally followed, hospitalized group of subjects. An algorithm combining measures of platelet MAO-B protein with the plasma levels of carbohydrate-deficient transferrin (CDT) and with liver enzymes (aspartate aminotransferase or γ-glutamyltransferase [GGT]) can detect hazardous/harmful alcohol use (HHAU) with the highest sensitivity and specificity in the cross-sectional nontreatment-seeking population. In the treatment-seeking population, low MAO-B protein levels at admission are associated with heavy drinking prior to admission, and these protein levels increase over a period of abstinence from alcohol.

CONCLUSIONS

The platelet MAO-B protein measurement is particularly effective for male alcohol consumers. The combined use of MAO-B protein measures together with measures of CDT and GGT does, however, improve the diagnostic utility of both markers for ascertaining HHAU in women. Furthermore, measurement of changes in platelet MAO-B protein levels during treatment for alcohol dependence may help monitor the success of the treatment program.

Comparative platelet proteome analysis reveals an increase of monoamine oxidase-B protein expression in Alzheimer's disease but not in non-demented Parkinson's disease patients

Monoamine oxidase-B (Mao-B) catalysing the breakdown of the neurotransmitter dopamine, is known to be involved in the pathophysiology of Parkinson's (PD) and Alzheimer's disease (AD). Increased brain Mao-B activity is associated with AD. This alteration can also be seen in platelets, albeit the cause has hitherto remained elusive. To gain a deeper understanding of the etiology of AD, the platelet proteome was characterised, (2D DIGE pH6-9, including Mao-B) from 150 individuals: 34 AD, 13 vascular dementia, 15 non-demented PD patients, 49 matched controls, 18 oldest old and 21 young individuals. One significant change was noted after applying false discovery rate with the upregulation of the Mao-B expression (30% adjusted P value<0.001; effect size 1.31) in AD compared to age- and sex-matched controls. In contrast, Mao-B levels were unchanged in PD to matched controls. Western blot and mRNA analyses verified these findings. Moreover, Mao-B concentration correlated with age in the cognitive healthy individuals (r=0.53; P<0.001) and PD patients but not in those suffering from AD (r=-0.03; P=0.874). Mao-B activity correlated with the increased Mao-B protein expression in AD (r=0.81; P=0.016). We suggest that Mao-B platelet protein level may serve as a biomarker for age-related dementia, especially AD.