Activation of a non-neuronal cholinergic system in visceral white adipose tissue of obese mice and humans

BACKGROUND AND OBJECTIVES

Since white adipose tissue (WAT) lacks parasympathetic cholinergic innervation, the source of the acetylcholine (ACh) acting on white adipocyte cholinergic receptors is unknown. This study was designed to identify ACh-producing cells in mouse and human visceral WAT and to determine whether a non-neuronal cholinergic system becomes activated in obese inflamed WAT.

METHODS

Mouse epididymal WAT (eWAT) and human omental fat were studied in normal and obese subjects. The expression of the key molecules involved in cholinergic signaling was evaluated by qRT-PCR and western blotting whereas their tissue distribution and cellular localization were investigated by immunohistochemistry, confocal microscopy and in situ hybridization. ACh levels were measured by liquid chromatography/tandem mass spectrometry. The cellular effects of ACh were assessed in cultured human multipotent adipose-derived stem cell (hMADS) adipocytes.

RESULTS

In mouse eWAT, diet-induced obesity modulated the expression of key cholinergic molecular components and, especially, raised the expression of choline acetyltransferase (ChAT), the ACh-synthesizing enzyme, which was chiefly detected in interstitial macrophages, in macrophages forming crown-like structures (CLSs), and in multinucleated giant cells (MGCs). The stromal vascular fraction of obese mouse eWAT contained significantly higher ACh and choline levels than that of control mice. ChAT was undetectable in omental fat from healthy subjects, whereas it was expressed in a number of interstitial macrophages, CLSs, and MGCs from some obese individuals. In hMADS adipocytes stressed with tumor necrosis factor α, ACh, alone or combined with rivastigmine, significantly blunted monocyte chemoattractant protein 1 and interleukin 6 expression, it partially but significantly, restored adiponectin and GLUT4 expression, and promoted glucose uptake.

CONCLUSIONS

In mouse and human visceral WAT, obesity induces activation of a macrophage-dependent non-neuronal cholinergic system that is capable of exerting anti-inflammatory and insulin-sensitizing effects on white adipocytes.

Cellular senescence and frailty: a comprehensive insight into the causal links

Senescent cells may have a prominent role in driving inflammation and frailty. The impact of cellular senescence on frailty varies depending on the assessment tool used, as it is influenced by the criteria or items predominantly affected by senescent cells and the varying weights assigned to these items across different health domains. To address this challenge, we undertook a thorough review of all available studies involving gain- or loss-of-function experiments as well as interventions targeting senescent cells, focusing our attention on those studies that examined outcomes based on the individual frailty phenotype criteria or specific items used to calculate two humans (35 and 70 items) and one mouse (31 items) frailty indexes. Based on the calculation of a simple "evidence score," we found that the burden of senescent cells related to musculoskeletal and cerebral health has the strongest causal link to frailty. We deem that insight into these mechanisms may not only contribute to clarifying the role of cellular senescence in frailty but could additionally provide multiple therapeutic opportunities to help the future development of a desirable personalized therapy in these extremely heterogeneous patients.

BNT162b2 Booster Dose Elicits a Robust Antibody Response in Subjects with Abdominal Obesity and Previous SARS-CoV-2 Infection

Little is known about the long-term durability of the induced immune response in subjects with obesity, particularly in those with an abdominal distribution of adipose tissue. We evaluated SARS-CoV-2-specific antibody responses after BNT162b2 vaccine booster dose, comparing individuals with and without abdominal obesity (AO), discerning between individuals previously infected or not. IgG-TrimericS were measured in 511 subjects at baseline, on the 21st day after vaccine dose 1, and at 1, 3, 6, and 9 months from dose 2, and at 1 and 3 months following the booster dose. To detect SARS-CoV-2 infection, nucleocapsid antibodies were measured at baseline and at the end of the study. Multivariable linear regression evaluated the three-month difference in the absolute variation in IgG-TrimericS levels from booster dose, showing AO and SARS-CoV-2 infection status interactions (p = 0.016). Regardless of possible confounding factors and IgG-TrimericS levels at the booster dose, AO is associated with a higher absolute change in IgG-TrimericS in prior infected individuals (p = 0.0125). In the same regression model, no interaction is highlighted using BMI (p = 0.418). The robust response in the development of antibodies after booster dose, observed in people with AO and previous infection, may support the recommendations to administer a booster dose in this population group.

An amino acid mixture, enriched with Krebs cycle intermediates, enhances extracellular matrix gene expression in cultured human fibroblasts

In the human body, the skin is one of the organs most affected by the aging process. Nutritional approaches aimed to counteract the age-induced decline of extracellular matrix (ECM) deposition could be a valuable tool to decrease the degenerative processes underlying skin aging. Here, we investigated the ability of a six-amino acid plus hyaluronic acid (6AAH) formulation enriched with tricarboxylic acid (TCA) intermediates to stimulate ECM gene expression. To this aim, human BJ fibroblasts were treated with 6AAH alone or plus succinate or malate alone or succinate plus malate (6AAHSM), and mRNA levels of several ECM markers were evaluated. 6AAHSM increased the expression of all the ECM markers significantly above 6AAH alone or plus only succinate or malate. Furthermore, in an in vitro oxidative damage model, 6AAHSM blunted the hydrogen peroxide-induced decline in ECM gene expression. Our data suggest that feeding cells with 6AAH enriched with TCAs could efficiently be employed as a non-pharmacological approach for counteracting skin aging.

Amino acids contribute to adaptive thermogenesis. New insights into the mechanisms of action of recent drugs for metabolic disorders are emerging

Adaptive thermogenesis is the heat production by muscle contractions (shivering thermogenesis) or brown adipose tissue (BAT) and beige fat (non-shivering thermogenesis) in response to external stimuli, including cold exposure. BAT and beige fat communicate with peripheral organs and the brain through a variegate secretory and absorption processes - controlling adipokines, microRNAs, extracellular vesicles, and metabolites - and have received much attention as potential therapeutic targets for managing obesity-related disorders. The sympathetic nervous system and norepinephrine-releasing adipose tissue macrophages (ATM) activate uncoupling protein 1 (UCP1), expressed explicitly in brown and beige adipocytes, dissolving the electrochemical gradient and uncoupling tricarboxylic acid cycle and the electron transport chain from ATP production. Mounting evidence has attracted attention to the multiple effects of dietary and endogenously synthesised amino acids in BAT thermogenesis and metabolic phenotype in animals and humans. However, the mechanisms implicated in these processes have yet to be conclusively characterized. In the present review article, we aim to define the principal investigation areas in this context, including intestinal microbiota constitution, adipose autophagy modulation, and secretome and metabolic fluxes control, which lead to increased brown/beige thermogenesis. Finally, also based on our recent epicardial adipose tissue results, we summarise the evidence supporting the notion that the new dual and triple agonists of glucagon-like peptide-1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP), and glucagon (GCG) receptor - with never before seen weight loss and insulin-sensitizing efficacy - promote thermogenic-like amino acid profiles in BAT with robust heat production and likely trigger sympathetic activation and adaptive thermogenesis by controlling amino acid metabolism and ATM expansion in BAT and beige fat.

Comprehensive longitudinal non-invasive quantification of healthspan and frailty in a large cohort (n = 546) of geriatric C57BL/6 J mice

Frailty is an age-related condition characterized by a multisystem functional decline, increased vulnerability to stressors, and adverse health outcomes. Quantifying the degree of frailty in humans and animals is a health measure useful for translational geroscience research. Two frailty measurements, namely the frailty phenotype (FP) and the clinical frailty index (CFI), have been validated in mice and are frequently applied in preclinical research. However, these two tools are based on different concepts and do not necessarily identify the same mice as frail. In particular, the FP is based on a dichotomous classification that suffers from high sample size requirements and misclassification problems. Based on the monthly longitudinal non-invasive assessment of frailty in a large cohort of mice, here we develop an alternative scoring method, which we called physical function score (PFS), proposed as a continuous variable that resumes into a unique function, the five criteria included in the FP. This score would not only reduce misclassification of frailty but it also makes the two tools, PFS and CFI, integrable to provide an overall measurement of health, named vitality score (VS) in aging mice. VS displays a higher association with mortality than PFS or CFI and correlates with biomarkers related to the accumulation of senescent cells and the epigenetic clock. This longitudinal non-invasive assessment strategy and the VS may help to overcome the different sensitivity in frailty identification, reduce the sample size in longitudinal experiments, and establish the effectiveness of therapeutic/preventive interventions for frailty or other age-related diseases in geriatric animals.

Comparison of Protein- or Amino Acid-Based Supplements in the Rehabilitation of Men with Severe Obesity: A Randomized Controlled Pilot Study

BACKGROUND

Weight loss is associated with a reduction in all body compartments, including muscle mass (MM), and this effect produces a decrease in function and muscle strength. Our objective was to assess the impact of protein or amino acid supplements on MM loss in middle-aged men (age < 65 years) with severe obesity (BMI > 35 kg/m2) during weight loss.

MATERIALS AND METHODS

We conducted a single-site randomized controlled trial (Clinicaltrials.gov NCT05143398) with 40 in-patient male subjects with severe obesity. Participants underwent an intervention program consisting of a low-calorie balanced diet and structured physical activity. They were randomly assigned to 4-week treatment groups: (1) control (CTR, N = 10), (2) protein (P, N = 10), (3) branched-chain amino acid (BCAA, N = 10), and (4) essential amino acid mixture with tricarboxylic acid cycle intermediates (PD-E07, N = 10) supplementation.

RESULTS

Following 4 weeks of intervention, all groups showed similar reductions in body weight compared to baseline. When examining the delta values, a notable increase in muscle mass (MM) was observed in the PD-E07 intervention group [MM (kg): 2.84 ± 3.57; MM (%): 3.63 ± 3.14], in contrast to the CTR group [MM (kg): -2.46 ± 3.04; MM (%): -0.47 ± 2.28], with a statistical significance of p = 0.045 and p = 0.023, respectively. However, the MM values for the P group [MM (kg): -2.75 ± 5.98, p = 0.734; MM (%): -0.44 ± 4.02, p = 0.990] and the BCAA group [MM (kg): -1 ± 3.3, p = 0.734; MM (%): 0.34 ± 2.85, p = 0.956] did not exhibit a statistically significant difference when compared to the CTR group.

CONCLUSIONS

Amino acid-based supplements may effectively mitigate the loss of MM typically observed during weight reduction. Further validation through large-scale studies is necessary.

A balanced formula of essential amino acids promotes brain mitochondrial biogenesis and protects neurons from ischemic insult

Mitochondrial dysfunction plays a key role in the aging process, and aging is a strong risk factor for neurodegenerative diseases or brain injury characterized by impairment of mitochondrial function. Among these, ischemic stroke is one of the leading causes of death and permanent disability worldwide. Pharmacological approaches for its prevention and therapy are limited. Although non-pharmacological interventions such as physical exercise, which promotes brain mitochondrial biogenesis, have been shown to exert preventive effects against ischemic stroke, regular feasibility is complex in older people, and nutraceutical strategies could be valuable alternatives. We show here that dietary supplementation with a balanced essential amino acid mixture (BCAAem) increased mitochondrial biogenesis and the endogenous antioxidant response in the hippocampus of middle-aged mice to an extent comparable to those elicited by treadmill exercise training, suggesting BCAAem as an effective exercise mimetic on brain mitochondrial health and disease prevention. In vitro BCAAem treatment directly exerted mitochondrial biogenic effects and induced antioxidant enzyme expression in primary mouse cortical neurons. Further, exposure to BCAAem protected cortical neurons from the ischemic damage induced by an in vitro model of cerebral ischemia (oxygen-glucose deprivation, OGD). BCAAem-mediated protection against OGD was abolished in the presence of rapamycin, Torin-1, or L-NAME, indicating the requirement of both mTOR and eNOS signaling pathways in the BCAAem effects. We propose BCAAem supplementation as an alternative to physical exercise to prevent brain mitochondrial derangements leading to neurodegeneration and as a nutraceutical intervention aiding recovery after cerebral ischemia in conjunction with conventional drugs.

Role of Portion Size in the Context of a Healthy, Balanced Diet: A Case Study of European Countries

Over the past decades, a generalised increase in food portion sizes has probably contributed to the growing global obesity epidemic. Increasing awareness of appropriate portion sizes could contribute to reversing this trend through better control of calorie intake. In this study, a comparison of standard portion sizes in European countries for various food categories shows a wide variability of their importance for food, nutrient, and energy consumption according to government and institutional websites. On the other hand, the overall averages appear to be largely in line with the values indicated by the Italian Society of Human Nutrition, which is the most comprehensive and detailed document among those evaluated. The exceptions are milk and yoghurt, for which the reference portions in Europe are generally higher, and vegetables and legumes, for which portions are smaller than those reported in the Italian document. Moreover, the portion sizes of staple foods (e.g., pasta and potatoes) vary according to different food traditions. It is reasonable to consider that the creation of harmonised standard reference portions common to the European countries, based on international guidelines and scientific evidence, would significantly contribute to consumers' nutritional education and ability to make informed choices for a healthy diet.

Human Epicardial Adipose Tissue Expresses Glucose-dependent Insulinotropic Polypeptide, Glucagon and Glucagon-Like Peptide 1 Receptors as Potential Targets of Pleiotropic Therapies

BACKGROUND

Human Epicardial Adipose Tissue (EAT) plays a crucial role in the development and progression of coronary artery disease, atrial fibrillation and heart failure. Microscopically, EAT is composed of adipocytes, nerve tissues, inflammatory, stromovascular and immune cells. EAT is a white adipose tissue, albeit it also has brown-fat like or beige fat features. No muscle fascia divides EAT and myocardium; this allows a direct interaction and cross talk between the epicardial fat and the myocardium. Thus, it might be a therapeutic target for pharmaceutical compounds acting on G-Protein-Coupled Receptors, such as those for Glucose-dependent Insulinotropic Polypeptide (GIP), Glucagon (GCG) and Glucagon-Like Peptide-1 (GLP-1), whose selective stimulation with innovative drugs has demonstrated beneficial cardiovascular effects. The precise mechanism of these novel drugs and their tissue and cellular target(s) need to be better understood.

AIM

We evaluate whether human EAT expresses GIP, GCG and GLP-1 receptors and whether their presence is related to EAT transcriptome. We also investigated protein expression and cell type localization specifically for GIPR and GCGR.

METHODS

EAT samples were collected from 33 patients affected by cardiovascular diseases undergoing open heart surgery (90.9% males, age 67.2±10.5 years mean ± SD). Microarray and immunohistochemistry analysis were performed.

RESULTS

Microarray analysis showed that GIPR and GCGR messenger Ribonucleic Acids (mRNAs) are expressed in EAT, beyond confirming the previously found GLP-1(3776±1377 arbitrary unit (A.U.), 17.77±14.91 A.U., and 3.41±2.27 A.U., respectively). The immunohistochemical analysis consistently indicates that GIPR and GCGR are expressed in EAT, mainly in macrophages, isolated and in crown-like structures. In contrast, only some mature adipocytes of different sizes showed cytoplasmic immunostaining, similar to endothelial cells and pericytes in the capillaries and pre-capillary vascular structures. Notably, EAT GIPR is statistically associated with the low expression of genes involved in Free Fatty Acid (FFA) oxidation and transport and those promoting FFA biosynthesis and adipogenesis (p<0.01). EAT GCGR, in turn, is related to genes involved in FFA transport, mitochondrial fatty acid oxidation, and white-to-brown adipocyte differentiation, in addition to genes involved in the reduction of fatty acid biosynthesis and adipogenesis (p<0.01).

CONCLUSIONS

Having reported the expression of the GLP-1 receptor previously, here, we showed that GIPR and GCGR similarly present at mRNA and protein levels in human EAT, particularly in macrophages and partially adipocytes, suggesting these G-protein-coupled receptors as pharmacological targets on the ongoing innovative drugs, which seem cardiometabolically healthy well beyond their effects on glucose and body weight..

Efficacy and tolerability of a specific blend of amino acids in patients with anorexia nervosa treated in a hospital setting: study protocol for a randomized controlled trial

BACKGROUND

Specific blends of essential amino acids (EAA) containing a high percentage of branched-chain amino acids preserves mitochondrial metabolism and higher physical resistance in elderly mice, increasing their survival and improving physical performance and cognitive functions in malnourished elderly patients. However, no study has been yet done on patients with anorexia nervosa (AN) who regain weight with specialized intensive treatment. The present study aims to evaluate the efficacy of supplementation with EAA on the change in lean body mass (LBM) and other physical and psychological outcomes in patients with AN who are undergoing specialist treatment for eating disorders.

METHODS

This is a 13-week randomized, double-blind, placebo-controlled study. Patients will be randomized to either a mixture of a complex blend of EAA and intermediates of the tricarboxylic acid (TCA) cycle (citrate, malate, succinate) supplementation (or placebo) upon admission at the intensive residential and day-hospital treatment for eating disorders. Ninety-two participants with AN aged 16-50 years will be recruited from a specialized intensive treatment of eating disorders. Double-blind assessment will be conducted at baseline (T0) and the end of the 13 weeks of treatment (T1). The study's primary aim is to evaluate the efficacy of supplementation with EAA and TCA intermediates on the change in lean body mass (LBM) with weight restoration in patients with AN who are undergoing specialist treatment for eating disorders. The secondary aims of the study are to assess the effect of dietary supplementation on physical fitness, weight restoration, modification of AN and general psychopathology, and psychosocial impairment.

DISCUSSION

The study's results will inform researchers and clinicians on whether supplementing a mixture of EAA and TCA cycle intermediates will improve the increase of LBM and other important physical and psychological outcomes in patients with AN who regain weight with specialized intensive treatment.

TRIAL REGISTRATION

NCT, NCT05290285. Registered on 22 March 2022.

Dietary essential amino acids for the treatment of heart failure with reduced ejection fraction

AIMS

Heart failure with reduced ejection fraction (HFrEF) is a leading cause of mortality worldwide, requiring novel therapeutic and lifestyle interventions. Metabolic alterations and energy production deficit are hallmarks and thereby promising therapeutic targets for this complex clinical syndrome. We aim to study the molecular mechanisms and effects on cardiac function in rodents with HFrEF of a designer diet in which free essential amino acids - in specifically designed percentages - substituted for protein.

METHODS AND RESULTS

Wild-type mice were subjected to transverse aortic constriction (TAC) to induce left ventricle (LV) pressure overload or sham surgery. Whole body glucose homeostasis was studied with glucose tolerance test, while myocardial dysfunction and fibrosis were measured with echocardiogram and histological analysis. Mitochondrial bioenergetics and morphology were investigated with oxygen consumption rate measurement and electron microscopy evaluation. Circulating and cardiac non-targeted metabolite profiles were analyzed by ultrahigh performance liquid chromatography-tandem mass spectroscopy, while RNA sequencing was used to identify signalling pathways mainly affected. The amino acid-substituted diet shows remarkable preventive and therapeutic effects. This dietary approach corrects the whole-body glucose metabolism and restores the unbalanced metabolic substrate usage - by improving mitochondrial fuel oxidation - in the failing heart. In particular, biochemical, molecular, and genetic approaches suggest that renormalization of branched-chain amino acid oxidation in cardiac tissue, which is suppressed in HFrEF, plays a relevant role. Beyond the changes of systemic metabolism, cell-autonomous processes may explain at least in part the diet's cardioprotective impact.

CONCLUSION

Collectively, these results suggest that manipulation of dietary amino acids, and especially essential amino acids, is a potential adjuvant therapeutic strategy to treat systolic dysfunction and HFrEF in humans.

The density of crown-like structures in epicardial adipose tissue could play a role in cardiovascular diseases

PURPOSE

The visceral fat of patients affected by abdominal obesity is inflamed, and the main histopathologic feature is the high density of crown-like structures (CLS). Epicardial adipose tissue (EAT) is a visceral fat of paramount importance for its relationships with coronary vessels and myocardium. Its inflammation in patients with abdominal obesity could be of clinical relevance, but histopathological studies on CLS density in EAT are lacking. This study aimed to assess the histopathology of EAT biopsies obtained from patients undergoing open-heart surgery.

METHODS

We collected EAT biopsies from 10 patients undergoing open-heart surgery for elective coronary artery bypass grafting (CABG) (n = 5) or valvular replacement (VR) (n = 5). Biopsies were treated for light microscopy and immunohistochemistry. We quantify the CLS density in each EAT sample.

RESULTS

Despite all patients having abdominal obesity, in EAT samples, no CLS were detected in the VR group; in contrast, CLS were detected in the CABG group (about 17 CLS/10⁴ adipocytes vs. 0.0 CLS/10⁴ adipocytes, CABG vs. VR group, respectively). An impressive density of CLS (100 times that of other patients) was found in one patient (LS) in the CABG group that had a relevant anamnestic aspect: relatively rapid increase of weight gain, especially in abdominal adipose tissue, coincident with myocardial infarction.

CONCLUSIONS

CLS density could be an important predictive tool for cardiovascular diseases. Furthermore, the LS case implies a role for timing in weight gain.

LEVEL OF EVIDENCE

No level of evidence; this is a basic science study.

A designer mixture of six amino acids promotes the extracellular matrix gene expression in cultured human fibroblasts

The deterioration of the skin is caused by dermatological disorders, environmental conditions, and ageing processes. One incisive strategy for supervising the skin ageing process is implementing healthy nutrition, preserving a balanced diet and a good supply of food supplements. Here, we compared H-Pro-Hyp-OH peptide, hydrolysed collagen, and an original mixture of six amino acids (we named 6aa)-including glycine, l-alanine, l-proline, l-valine, l-leucine, and l-lysine-effects on the production of extracellular matrix (ECM) components, particularly the elastin, fibronectin, collagen 1, and collagen 4. Treatment of BJ human skin fibroblasts with the 6aa mixture upregulated elastin, fibronectin, and collagen 1 gene expression, without affecting the expression of anti-reactive oxygen species enzymes. Moreover, the mTOR signaling pathway seems to be involved, at least in part. Collectively, these results suggest that the six amino acid mixture exerts beneficial effects in human skin fibroblasts.

Molecular and metabolic effects of extra-virgin olive oil on the cardiovascular gene signature in rodents

BACKGROUND AND AIMS

Overweight and obesity are major risk factors for degenerative diseases, including cardiometabolic disorders and cancer. Research on fat and fatty acids' type is attracting less attention than that on carbohydrates. High adherence to a Mediterranean diet is associated with a better prognosis. One characteristic of the Mediterranean diet is extra-virgin olive oil (EVOO) as the foremost source of dietary fat. EVOO is different from other vegetable oils because it contains peculiar "minor" components, mainly phenolic in nature. Even though olive oil is highly caloric, unrestricted use of olive oil in the PREDIMED trial did not result in weight gain. We sought to study the effects of EVOO in an appropriate mouse model of increased body weight. Furthermore, we explored the biochemical and metabolomic responses to EVOO consumption.

METHODS AND RESULTS

C57BL/6N male mice were weight-matched and fed ad libitum with the following diets, for 16 weeks: 1) saturated fatty acid diet (SFA) or 2) extra-virgin olive oil diet (EVOO), a custom-prepared diet, isocaloric compared to SFA, in which 82% of fat was replaced by high (poly)phenol EVOO. We evaluated glucose homeostasis, serum biochemistry and plasma metabolomics, in addition to cardiac and hepatic gene profile, and mitochondrial respiration rate.

CONCLUSION

Replacing saturated fatty acids (e.g. lard) with EVOO translates into moderate yet beneficial cardiometabolic and hepatic effects. Future research will further clarify the mechanisms of action of EVOO (poly)phenols and their role in a balanced diet.

Front-of-pack (FOP) labelling systems to improve the quality of nutrition information to prevent obesity: NutrInform Battery vs Nutri-Score

Many systems for classifying food products to adequately predict lower all-cause morbidity and mortality have been proposed as front-of-pack (FOP) nutritional labels. Although the efforts and advances that these systems represent for public health must be appreciated, as scientists involved in nutrition research and belonging to diverse Italian nutrition scientific societies, we would like to draw stakeholders' attention to the fact that some FOP labels risk being not correctly informative to consumers' awareness of nutritional food quality. The European Commission has explicitly called for such a nutrition information system to be part of the European "strategy on nutrition, overweight and obesity-related issues" to "facilitate consumer understanding of the contribution or importance of the food to the energy and nutrient content of a diet". Some European countries have adopted the popular French proposal Nutri-Score. However, many critical limits and inadequacies have been identified in this system. As an alternative, we endorse a new enriched informative label-the NutrInform Battery-promoted by the Italian Ministry of Health and deeply studied by the Center for Study and Research on Obesity, Milan University. Therefore, the present position paper limits comparing these two FOP nutritional labels, focusing on the evidence suggesting that the NutrInform Battery can help consumers better than the Nutri-Score system to understand nutritional information, potentially improving dietary choices. LEVEL OF EVIDENCE: II. Evidence was obtained from well-designed controlled trials without randomization.

An original amino acid formula favours in vitro corneal epithelial wound healing by promoting Fn1, ITGB1, and PGC-1α expression

Corneal disorders are frequent, involving most diabetic patients; among its manifestations, they include delayed wound healing. Since maintenance of mitochondrial homeostasis is fundamental for the cell, stimulation of mitochondrial biogenesis represents a unique therapeutic tool for preventing and treating disorders with a deficit in energy metabolism. We have recently demonstrated that a branched-chain amino acid (BCAA)-enriched mixture (BCAAem) supported mitochondrial biogenesis in cardiac and skeletal muscle, reduced liver damage caused by alcohol, and prevented the doxorubicin-dependent mitochondrial damage in cardiomyocytes. The present study aimed to investigate a new amino acid mixture, named six amino acids (6AA), to promote corneal epithelial wound healing by regulating mitochondrial biogenesis. A murine epithelium cell line (TKE2) exposed to this mixture showed increased mitochondrial biogenesis markers, fibronectin 1 (Fn1) and integrin beta 1 (ITGB1) involved in extracellular matrix synthesis and cell migration. Most importantly, the 6AA mixture completely restored the wound in scratch assays, confirming the potential of this new formula in eye disorders like keratopathy. Moreover, our results demonstrate for the first time that peroxisome proliferator-receptor γ coactivator 1 α (PGC-1α) is expressed in TKE2 cells, which controls mitochondrial function and corneal repair process. These results could be relevant for the treatment mainly focused on corneal re-epithelialisation.

Antibody responses to BNT162b2 mRNA vaccine: Infection-naïve individuals with abdominal obesity warrant attention

OBJECTIVE

The excess of visceral adipose tissue might hinder and delay immune response. How people with abdominal obesity (AO) will respond to mRNA vaccines against SARS-CoV-2 is yet to be established. SARS-CoV-2-specific antibody responses were evaluated after the first and second dose of the BNT162b2 mRNA vaccine, comparing the response of individuals with AO with the response of those without, and discerning between individuals with or without prior infection.

METHODS

Immunoglobulin G (IgG)-neutralizing antibodies against the Trimeric complex (IgG-TrimericS) were measured at four time points: at baseline, at day 21 after vaccine dose 1, and at 1 and 3 months after dose 2. Nucleocapsid antibodies were assessed to detect prior SARS-CoV-2 infection. Waist circumference was measured to determine AO.

RESULTS

Between the first and third month after vaccine dose 2, the drop in IgG-TrimericS levels was more remarkable in individuals with AO compared with those without AO (2.44-fold [95% CI: 2.22-2.63] vs. 1.82-fold [95% CI: 1.69-1.92], respectively, p < 0.001). Multivariable linear regression confirmed this result after inclusion of assessed confounders (p < 0.001).

CONCLUSIONS

The waning antibody levels in individuals with AO may further support recent recommendations to offer booster vaccines to adults with high-risk medical conditions, including obesity, and particularly to those with a more prevalent AO phenotype.

Therapeutic Induction of Energy Metabolism Reduces Neural Tissue Damage and Increases Microglia Activation in Severe Spinal Cord Injury

Neural tissue has high metabolic requirements. Following spinal cord injury (SCI), the damaged, tissue suffers from a severe metabolic impairment, which aggravates axonal degeneration and, neuronal loss. Impaired cellular energetic, tricarboxylic acid (TCA) cycle and oxidative, phosphorylation metabolism in neuronal cells has been demonstrated to be a major cause of neural tissue death and regeneration failure following SCI. Therefore, rewiring the spinal cord cell metabolism may be an innovative therapeutic strategy for the treatment of SCI. In this study, we evaluated the therapeutic effect of the recovery of oxidative metabolism in a mouse model of severe contusive SCI. Oral administration of TCA cycle intermediates, co-factors, essential amino acids, and branched-chain amino acids was started 3 days post-injury and continued until the end of the experimental procedures. Metabolomic, immunohistological, and biochemical analyses were performed on the injured spinal cord sections. Administration of metabolic precursors enhanced spinal cord oxidative metabolism. In line with this metabolic shift, we observed the activation of the mTORC1 anabolic pathway, the increase in mitochondrial mass, and ROS defense which effectively prevented the injury-induced neural cell apoptosis in treated animals. Consistently, we found more choline acetyltransferase (ChAT)-expressing motor neurons and increased neurofilament positive corticospinal axons in the spinal cord parenchyma of the treated mice. Interestingly, oral administration of the metabolic precursors increased the number of activated microglia expressing the CD206 marker suggestive of a, pro-resolutive, M2-like phenotype. These molecular and histological modifications observed in treated animals ultimately led to a significant, although partial, improvement of the motor functions. Our data demonstrate that rewiring the cellular metabolism can represent an effective strategy to treat SCI.

Paracetamol: A Review of Guideline Recommendations

Musculoskeletal pain conditions are age-related, leading contributors to chronic pain and pain-related disability, which are expected to rise with the rapid global population aging. Current medical treatments provide only partial relief. Furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) and opioids are effective in young and otherwise healthy individuals but are often contraindicated in elderly and frail patients. As a result of its favorable safety and tolerability record, paracetamol has long been the most common drug for treating pain. Strikingly, recent reports questioned its therapeutic value and safety. This review aims to present guideline recommendations. Paracetamol has been assessed in different conditions and demonstrated therapeutic efficacy on both acute and chronic pain. It is active as a single agent and is additive or synergistic with NSAIDs and opioids, improving their efficacy and safety. However, a lack of significant efficacy and hepatic toxicity have also been reported. Fast dissolving formulations of paracetamol provide superior and more extended pain relief that is similar to intravenous paracetamol. A dose reduction is recommended in patients with liver disease or malnourished. Genotyping may improve efficacy and safety. Within the current trend toward the minimization of opioid analgesia, it is consistently included in multimodal, non-opioid, or opioid-sparing therapies. Paracetamol is being recommended by guidelines as a first or second-line drug for acute pain and chronic pain, especially for patients with limited therapeutic options and for the elderly.

COVID-19 and Hartnup disease: an affair of intestinal amino acid malabsorption

Since the outbreak of COVID-19, clinicians have tried every effort to fight the disease, and multiple drugs have been proposed. However, no proven effective therapies currently exist, and different clinical phenotypes complicate the situation. In clinical practice, many severe or critically ill COVID-19 patients developed gastrointestinal (GI) disturbances, including vomiting, diarrhoea, or abdominal pain, even in the absence of cough and dyspnea. Understanding the mechanism of GI disturbances is warranted for exploring better clinical care for COVID-19 patients. With evidence collected from clinical studies on COVID-19 and basic research on a rare genetic disease (i.e., Hartnup disorder), we put forward a novel hypothesis to elaborate an effective nutritional therapy. We hypothesize that SARS-CoV-2 spike protein, binding to intestinal angiotensin-converting enzyme 2, negatively regulates the absorption of neutral amino acids, and this could explain not only the GI, but also systemic disturbances in COVID-19. Amino acid supplements could be recommended.Level of evidence No level of evidence: Hypothesis article.

Essential amino acid formulations to prevent mitochondrial dysfunction and oxidative stress

PURPOSE OF REVIEW

Both restriction and supplementation of specific amino acids or branched-chain amino acids (BCAAs) are described to improve metabolic homeostasis, energy balance, and health span. This review will discuss the recent findings of the role of amino acid supplements in the regulation of mitochondrial health.

RECENT FINDINGS

A mixture of essential amino acids (EAAs), BCAA enriched mixture, was found to extend healthy life span in elderly mice and prevent multiple diseases associated with an energy deficit, similarly to caloric restriction or fasting-mimicking diets. A growing body of evidence highlights mitochondria as the central target of this supplement: it promotes mitochondrial biogenesis and the activation of antioxidant defence systems in different physiological (e.g., exercise or ageing) or pathological conditions (e.g., sarcopenia, muscular dystrophy, liver steatosis, or impaired cognition). Based on these results, new formulas have been created enriched with Krebs cycle substrates, behaving more efficiently than BCAA enriched mixture.

SUMMARY

EAA-BCAA balanced supplements might be valuable not only for healthy individuals undergoing to energy deficit (e.g., athletes) during strenuous exercise or training but also against diseases characterized by a dysregulated catabolic state or mitochondrial dysfunction, such as age-related disorders. The associated mechanistic processes should be identified as potential pharmacological targets.

The European Association for the Study of Obesity (EASO) Endorses the Milan Charter on Urban Obesity

The Milan Charter on Urban Obesity highlights the challenges of urban environments as a battleground for human health, as cities are often organized to subvert public health goals, and promote rather than prevent the development of obesity and consequent non-communicable diseases. The Charter articulates ten principles which detail actions and strategies through which general practitioners, diverse medical specialists, related healthcare professionals, administrators and healthcare practice managers, policy actors - within health systems and at a national level - along with experts across disciplines, and citizens, can work in cooperation to meet this challenge and improve public health. The Charter urges the adoption of decisions that deliver the following: (i) policies which enable our cities to become healthier and less obesogenic, more supportive of well-being and less health-disruptive in general, and (ii) policies that fully support primary prevention strategies, that address social stigma, and that ensure fair access to treatment for people living with obesity. The Milan Charter on Urban Obesity aims to raise awareness of our shared responsibility for the health of all citizens, and focuses on addressing the health of people living with obesity - not only as a challenge in its own right, but a gateway to other major non-communicable diseases, including cardiovascular diseases, type 2 diabetes, and some cancers.

Manipulation of Dietary Amino Acids Prevents and Reverses Obesity in Mice Through Multiple Mechanisms That Modulate Energy Homeostasis

Reduced activation of energy metabolism increases adiposity in humans and other mammals. Thus, exploring dietary and molecular mechanisms able to improve energy metabolism is of paramount medical importance because such mechanisms can be leveraged as a therapy for obesity and related disorders. Here, we show that a designer protein-deprived diet enriched in free essential amino acids can 1) promote the brown fat thermogenic program and fatty acid oxidation, 2) stimulate uncoupling protein 1 (UCP1)-independent respiration in subcutaneous white fat, 3) change the gut microbiota composition, and 4) prevent and reverse obesity and dysregulated glucose homeostasis in multiple mouse models, prolonging the healthy life span. These effects are independent of unbalanced amino acid ratio, energy consumption, and intestinal calorie absorption. A brown fat-specific activation of the mechanistic target of rapamycin complex 1 seems involved in the diet-induced beneficial effects, as also strengthened by in vitro experiments. Hence, our results suggest that brown and white fat may be targets of specific amino acids to control UCP1-dependent and -independent thermogenesis, thereby contributing to the improvement of metabolic health.

Targeting Multiple Mitochondrial Processes by a Metabolic Modulator Prevents Sarcopenia and Cognitive Decline in SAMP8 Mice

The age-dependent declines of skeletal muscle and cognitive functions often coexist in elderly subjects. The underlying pathophysiological mechanisms share common features of mitochondrial dysfunction, which plays a central role in the development of overt sarcopenia and/or dementia. Dietary supplementation with formulations of essential and branched-chain amino acids (EAA-BCAA) is a promising preventive strategy because it can preserve mitochondrial biogenesis and function. The senescence-accelerated mouse prone 8 (SAMP8) is considered an accurate model of age-related muscular and cognitive alterations. Hence, we aimed to investigate the progression of mitochondrial dysfunctions during muscular and cognitive aging of SAMP8 mice and to study the effects of a novel EAA-BCAA-based metabolic modulator on these changes. We evaluated body condition, motor endurance, and working memory of SAMP8 mice at 5, 9, 12, and 15 months of age. Parallel changes in protein levels of mitochondrial respiratory chain subunits, regulators of mitochondrial biogenesis and dynamics, and the antioxidant response, as well as respiratory complex activities, were measured in the quadriceps femoris and the hippocampus. The same variables were assessed in 12-month-old SAMP8 mice that had received dietary supplementation with the novel EAA-BCAA formulation, containing tricarboxylic acid cycle intermediates and co-factors (PD-0E7, 1.5 mg/kg/body weight/day in drinking water) for 3 months. Contrary to untreated mice, which had a significant molecular and phenotypic impairment, PD-0E7-treated mice showed preserved healthy body condition, muscle weight to body weight ratio, motor endurance, and working memory at 12 months of age. The PD-0E7 mixture increased the protein levels and the enzymatic activities of mitochondrial complex I, II, and IV and the expression of proliferator-activated receptor γ coactivator-1α, optic atrophy protein 1, and nuclear factor, erythroid 2 like 2 in muscles and hippocampi. The mitochondrial amyloid-β-degrading pitrilysin metallopeptidase 1 was upregulated, while amyloid precursor protein was reduced in the hippocampi of PD-0E7 treated mice. In conclusion, we show that a dietary supplement tailored to boost mitochondrial respiration preserves skeletal muscle and hippocampal mitochondrial quality control and health. When administered at the early onset of age-related physical and cognitive decline, this novel metabolic inducer counteracts the deleterious effects of precocious aging in both domains.

Non-invasive investigation of adipose tissue by time domain diffuse optical spectroscopy

The human abdominal region is very heterogeneous and stratified with subcutaneous adipose tissue (SAT) being one of the primary layers. Monitoring this tissue is crucial for diagnostic purposes and to estimate the effects of interventions like caloric restriction or bariatric surgery. However, the layered nature of the abdomen poses a major problem in monitoring the SAT in a non-invasive way by diffuse optics. In this work, we examine the possibility of using multi-distance broadband time domain diffuse optical spectroscopy to assess the human abdomen non-invasively. Broadband absorption and reduced scattering spectra from 600 to 1100 nm were acquired at 1, 2 and 3 cm source-detector distances on ten healthy adult male volunteers, and then analyzed using a homogeneous model as an initial step to understand the origin of the detected signal and how tissue should be modeled to derive quantitative information. The results exhibit a clear influence of the layered nature on the estimated optical properties. Clearly, the underlying muscle makes a relevant contribution in the spectra measured at the largest source-detector distance for thinner subjects related to blood and water absorption. More unexpectedly, also the thin superficial skin layer yields a direct contamination, leading to higher water content and steeper reduced scattering spectra at the shortest distance, as confirmed also by simulations. In conclusion, provided that data analysis properly accounts for the complex tissue structure, diffuse optics may offer great potential for the continuous non-invasive monitoring of abdominal fat.

A Special Amino-Acid Formula Tailored to Boosting Cell Respiration Prevents Mitochondrial Dysfunction and Oxidative Stress Caused by Doxorubicin in Mouse Cardiomyocytes

Anthracycline anticancer drugs, such as doxorubicin (DOX), can induce cardiotoxicity supposed to be related to mitochondrial damage. We have recently demonstrated that a branched-chain amino acid (BCAA)-enriched mixture (BCAAem), supplemented with drinking water to middle-aged mice, was able to promote mitochondrial biogenesis in cardiac and skeletal muscle. To maximally favor and increase oxidative metabolism and mitochondrial function, here we tested a new original formula, composed of essential amino acids, tricarboxylic acid cycle precursors and co-factors (named α5), in HL-1 cardiomyocytes and mice treated with DOX. We measured mitochondrial biogenesis, oxidative stress, and BCAA catabolic pathway. Moreover, the molecular relevance of endothelial nitric oxide synthase (eNOS) and mechanistic/mammalian target of rapamycin complex 1 (mTORC1) was studied in both cardiac tissue and HL-1 cardiomyocytes. Finally, the role of Krüppel-like factor 15 (KLF15), a critical transcriptional regulator of BCAA oxidation and eNOS-mTORC1 signal, was investigated. Our results demonstrate that the α5 mixture prevents the DOX-dependent mitochondrial damage and oxidative stress better than the previous BCAAem, implying a KLF15/eNOS/mTORC1 signaling axis. These results could be relevant for the prevention of cardiotoxicity in the DOX-treated patients.

Blockade of IGF2R improves muscle regeneration and ameliorates Duchenne muscular dystrophy

Duchenne muscular dystrophy (DMD) is a debilitating fatal X-linked muscle disorder. Recent findings indicate that IGFs play a central role in skeletal muscle regeneration and development. Among IGFs, insulinlike growth factor 2 (IGF2) is a key regulator of cell growth, survival, migration and differentiation. The type 2 IGF receptor (IGF2R) modulates circulating and tissue levels of IGF2 by targeting it to lysosomes for degradation. We found that IGF2R and the store-operated Ca2+ channel CD20 share a common hydrophobic binding motif that stabilizes their association. Silencing CD20 decreased myoblast differentiation, whereas blockade of IGF2R increased proliferation and differentiation in myoblasts via the calmodulin/calcineurin/NFAT pathway. Remarkably, anti-IGF2R induced CD20 phosphorylation, leading to the activation of sarcoplasmic/endoplasmic reticulum Ca2+ -ATPase (SERCA) and removal of intracellular Ca2+ . Interestingly, we found that IGF2R expression was increased in dystrophic skeletal muscle of human DMD patients and mdx mice. Blockade of IGF2R by neutralizing antibodies stimulated muscle regeneration, induced force recovery and normalized capillary architecture in dystrophic mdx mice representing an encouraging starting point for the development of new biological therapies for DMD.

From mitochondria to healthy aging: The role of branched-chain amino acids treatment: MATeR a randomized study

RATIONALE

Malnutrition often affects elderly patients and significantly contributes to the reduction in healthy life expectancy, causing high morbidity and mortality. In particular, protein malnutrition is one of the determinants of frailty and sarcopenia in elderly people.

METHODS

To investigate the role of amino acid supplementation in senior patients we performed an open-label randomized trial and administered a particular branched-chain amino acid enriched mixture (BCAAem) or provided diet advice in 155 elderly malnourished patients. They were followed for 2 months, assessing cognitive performance by Mini Mental State Examination (MMSE), muscle mass measured by anthropometry, strength measure by hand grip and performance measured by the Timed Up and Go (TUG) test, the 30 s Chair Sit to Stand (30-s CST) test and the 4 m gait speed test. Moreover we measured oxidative stress in plasma and mitochondrial production of ATP and electron flux in peripheral blood mononuclear cells.

RESULTS

Both groups improved in nutritional status, general health and muscle mass, strength and performance; treatment with BCAAem supplementation was more effective than simple diet advice in increasing MMSE (1.2 increase versus 0.2, p = 0.0171), ATP production (0.43 increase versus -0.1, p = 0.0001), electron flux (0.50 increase versus 0.01, p < 0.0001) and in maintaining low oxidative stress. The amelioration of clinical parameters as MMSE, balance, four meter walking test were associated to increased mitochondrial function.

CONCLUSIONS

Overall, our findings show that sustaining nutritional support might be clinically relevant in increasing physical performance in elderly malnourished patients and that the use of specific BCAAem might ameliorate also cognitive performance thanks to an amelioration of mitochondria bioenergetics.

Supplementation with a selective amino acid formula ameliorates muscular dystrophy in mdx mice

Duchenne muscular dystrophy (DMD) is one of the most common and severe forms of muscular dystrophy. Oxidative myofibre content, muscle vasculature architecture and exercise tolerance are impaired in DMD. Several studies have demonstrated that nutrient supplements ameliorate dystrophic features, thereby enhancing muscle performance. Here, we report that dietary supplementation with a specific branched-chain amino acid-enriched mixture (BCAAem) increased the abundance of oxidative muscle fibres associated with increased muscle endurance in dystrophic mdx mice. Amelioration of the fatigue index in BCAAem-treated mdx mice was caused by a cascade of events in the muscle tissue, which were promoted by endothelial nitric oxide synthase (eNOS) activation and vascular endothelial growth factor (VEGF) expression. VEGF induction led to recruitment of bone marrow (BM)-derived endothelial progenitors (EPs), which increased the capillary density of dystrophic skeletal muscle. Functionally, BCAAem mitigated the dystrophic phenotype of mdx mice without inducing dystrophin protein expression or replacing the dystrophin-associated glycoprotein (DAG) complex in the membrane, which is typically lost in DMD. BCAAem supplementation could be an effective adjuvant strategy in DMD treatment.

A specific amino acid formula prevents alcoholic liver disease in rodents

Chronic alcohol consumption promotes mitochondrial dysfunction, oxidative stress, defective protein metabolism, and fat accumulation in hepatocytes (liver steatosis). Inadequate amino acid metabolism is worsened by protein malnutrition, frequently present in alcohol-consuming patients, with reduced circulating branched-chain amino acids (BCAAs). Here we asked whether dietary supplementation with a specific amino acid mixture, enriched in BCAAs (BCAAem) and able to promote mitochondrial function in muscle of middle-aged rodents, would prevent mitochondrial dysfunction and liver steatosis in Wistar rats fed on a Lieber-DeCarli ethanol (EtOH)-containing liquid diet. Supplementation of BCAAem, unlike a mixture based on the amino acid profile of casein, abrogated the EtOH-induced fat accumulation, mitochondrial impairment, and oxidative stress in liver. These effects of BCAAem were accompanied by normalization of leucine, arginine, and tryptophan levels, which were reduced in liver of EtOH-consuming rats. Moreover, although the EtOH exposure of HepG2 cells reduced mitochondrial DNA, mitochondrial transcription factors, and respiratory chain proteins, the BCAAem but not casein-derived amino acid supplementation halted this mitochondrial toxicity. Nicotinamide adenine dinucleotide levels and sirtuin 1 (Sirt1) expression, as well as endothelial nitric oxide (eNOS) and mammalian/mechanistic target of rapamycin (mTOR) signaling pathways, were downregulated in the EtOH-exposed HepG2 cells. BCAAem reverted these molecular defects and the mitochondrial dysfunction, suggesting that the mitochondrial integrity obtained with the amino acid supplementation could be mediated through a Sirt1-eNOS-mTOR pathway. Thus a dietary activation of the mitochondrial biogenesis and function by a specific amino acid supplement protects against the EtOH toxicity and preserves the liver integrity in mammals. NEW & NOTEWORTHY Dietary supplementation of a specific amino acid formula prevents both fat accumulation and mitochondrial dysfunction in hepatocytes of alcohol-consuming rats. These effects are accompanied also by increased expression of anti-reactive oxygen species genes. The amino acid-protective effects likely reflect activation of sirtuin 1-endothelial nitric oxide synthase-mammalian target of rapamycin pathway able to regulate the cellular energy balance of hepatocytes exposed to chronic, alcoholic damage.

Adipocyte cannabinoid receptor CB1 regulates energy homeostasis and alternatively activated macrophages

Dysregulated adipocyte physiology leads to imbalanced energy storage, obesity, and associated diseases, imposing a costly burden on current health care. Cannabinoid receptor type-1 (CB1) plays a crucial role in controlling energy metabolism through central and peripheral mechanisms. In this work, adipocyte-specific inducible deletion of the CB1 gene (Ati-CB1-KO) was sufficient to protect adult mice from diet-induced obesity and associated metabolic alterations and to reverse the phenotype in already obese mice. Compared with controls, Ati-CB1-KO mice showed decreased body weight, reduced total adiposity, improved insulin sensitivity, enhanced energy expenditure, and fat depot-specific cellular remodeling toward lowered energy storage capacity and browning of white adipocytes. These changes were associated with an increase in alternatively activated macrophages concomitant with enhanced sympathetic tone in adipose tissue. Remarkably, these alterations preceded the appearance of differences in body weight, highlighting the causal relation between the loss of CB1 and the triggering of metabolic reprogramming in adipose tissues. Finally, the lean phenotype of Ati-CB1-KO mice and the increase in alternatively activated macrophages in adipose tissue were also present at thermoneutral conditions. Our data provide compelling evidence for a crosstalk among adipocytes, immune cells, and the sympathetic nervous system (SNS), wherein CB1 plays a key regulatory role.

Amino acid supplements and metabolic health: a potential interplay between intestinal microbiota and systems control

Dietary supplementation of essential amino acids (EAAs) has been shown to promote healthspan. EAAs regulate, in fact, glucose and lipid metabolism and energy balance, increase mitochondrial biogenesis, and maintain immune homeostasis. Basic science and epidemiological results indicate that dietary macronutrient composition affects healthspan through multiple and integrated mechanisms, and their effects are closely related to the metabolic status to which they act. In particular, EAA supplementation can trigger different and even opposite effects depending on the catabolic and anabolic states of the organisms. Among others, gut-associated microbial communities (referred to as gut microbiota) emerged as a major regulator of the host metabolism. Diet and host health influence gut microbiota, and composition of gut microbiota, in turn, controls many aspects of host health, including nutrient metabolism, resistance to infection, and immune signals. Altered communication between the innate immune system and the gut microbiota might contribute to complex diseases. Furthermore, gut microbiota and its impact to host health change largely during different life phases such as lactation, weaning, and aging. Here we will review the accumulating body of knowledge on the impact of dietary EAA supplementation on the host metabolic health and healthspan from a holistic perspective. Moreover, we will focus on the current efforts to establish causal relationships among dietary EAAs, gut microbiota, and health during human development.

Branched-chain amino acids differently modulate catabolic and anabolic states in mammals: a pharmacological point of view

Substantial evidence has been accumulated suggesting that branched-chain amino acid (BCAA) supplementation or BCAA-rich diets have a positive effect on the regulation of body weight, muscle protein synthesis, glucose homeostasis, the ageing process and extend healthspan. Despite these beneficial effects, epidemiological studies have shown that BCAA plasma concentrations and BCAA metabolism are altered in several metabolic disorders, including type 2 diabetes mellitus and cardiovascular diseases. In this review article, we present an overview of the current literature on the different effects of BCAAs in health and disease. We also highlight the results showing the most promising therapeutic effects of dietary BCAA supplementation and discuss how BCAAs can trigger different and even opposite effects, depending on the catabolic and anabolic states of the organisms. Moreover, we consider the effects of BCAAs when metabolism is abnormal, in the presence of a mixture of different anabolic and catabolic signals. These unique pharmacodynamic properties may partially explain some of the markedly different effects found in BCAA supplementation studies. To predict accurately these effects, the overall catabolic/anabolic status of patients should be carefully considered. In wider terms, a correct modulation of metabolic disorders would make nutraceutical interventions with BCAAs more effective.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

A Peculiar Formula of Essential Amino Acids Prevents Rosuvastatin Myopathy in Mice

AIMS

Myopathy, characterized by mitochondrial oxidative stress, occurs in ∼10% of statin-treated patients, and a major risk exists with potent statins such as rosuvastatin (Rvs). We sought to determine whether a peculiar branched-chain amino acid-enriched mixture (BCAAem), found to improve mitochondrial function and reduce oxidative stress in muscle of middle-aged mice, was able to prevent Rvs myopathy.

RESULTS

Dietary supplementation of BCAAem was able to prevent the structural and functional alterations of muscle induced by Rvs in young mice. Rvs-increased plasma 3-methylhistidine (a marker of muscular protein degradation) was prevented by BCAAem. This was obtained without changes of Rvs ability to reduce cholesterol and triglyceride levels in blood. Rather, BCAAem promotes de novo protein synthesis and reduces proteolysis in cultured myotubes. Morphological alterations of C2C12 cells induced by statin were counteracted by amino acids, as were the Rvs-increased atrogin-1 mRNA and protein levels. Moreover, BCAAem maintained mitochondrial mass and density and citrate synthase activity in skeletal muscle of Rvs-treated mice beside oxygen consumption and ATP levels in C2C12 cells exposed to statin. Notably, BCAAem assisted Rvs to reduce oxidative stress and to increase the anti-reactive oxygen species (ROS) defense system in skeletal muscle. Innovation and Conclusions: The complex interplay between proteostasis and antioxidant properties may underlie the mechanism by which a specific amino acid formula preserves mitochondrial efficiency and muscle health in Rvs-treated mice. Strategies aimed at promoting protein balance and controlling mitochondrial ROS level may be used as therapeutics for the treatment of muscular diseases involving mitochondrial dysfunction, such as statin myopathy. Antioxid. Redox Signal. 25, 595-608.

Healthspan and longevity in mammals: a family game for cellular organelles?

Healthy mitochondria are essential generators of cellular energy, while senescent or damaged mitochondria are bioenergetically inefficient and are sources of reactive oxygen species. The mitochondrial life cycle, comprising biogenesis, fusion/fission events and mitophagic elimination, is carefully orchestrated, and age-related decay of the lifecycle contributes to chronic degenerative diseases. Mitochondria make contacts with other cellular organelles in the endomembrane system (endoplasmic reticulum, peroxisomes and lysosomes) whose dynamics are co-regulated and interactions finely tuned to meet the cell requirements and maintain the health of the organism. This review will consider the evidence that mitochondrial biogenesis and quality control, as well as the complex interplay among cellular organelles, may be affected by the aging process(es), with negative consequences for the well being of elderly individuals. Moreover, we propose that nutrients or drugs able to maintain organelle homeostasis may represent novel preventive and/or therapeutic approaches for chronic age-related diseases.

Nitric oxide, interorganelle communication, and energy flow: a novel route to slow aging

The mitochondrial lifecycle (mitochondrial biogenesis, dynamics, and removal by mitophagy) is carefully orchestrated to ensure the efficient generation of cellular energy and to maintain reactive oxygen species (ROS) production within an optimal range for cellular health. Based on latest research, these processes largely depend on mitochondrial interactions with other cell organelles, so that the ER- and peroxisome-mitochondrial connections might intervene in the control of cellular energy flow. Damaged organelles are cleared by autophagic mechanisms to assure the quality and proper function of the intracellular organelle pool. Nitric oxide (NO) generated through the endothelial nitric oxide synthase (eNOS) acts a gas signaling mediator to promote mitochondrial biogenesis and bioenergetics, with a favorable impact in diverse chronic diseases of the elderly. Obesity, diabetes and aging share common pathophysiological mechanisms, including mitochondrial impairment and dysfunctional eNOS. Here we review the evidences that eNOS-dependent mitochondrial biogenesis and quality control, and possibly the complex interplay among cellular organelles, may be affected by metabolic diseases and the aging processes, contributing to reduce healthspan and lifespan. Drugs or nutrients able to sustain the eNOS-NO generating system might contribute to maintain organelle homeostasis and represent novel preventive and/or therapeutic approaches to chronic age-related diseases.

Dietary supplementation with essential amino acids boosts the beneficial effects of rosuvastatin on mouse kidney

The effects of high-potency statins on renal function are controversial. To address the impact of statins on renal morpho-functional aspects, normotensive young mice were treated with rosuvastatin (Rvs). Moreover, because statins may impair mitochondrial function, mice received either dietary supplementation with an amino acid mixture enriched in essential amino acids (EAAm), which we previously demonstrated to increase mitochondrial biogenesis in muscle or an unsupplemented control diet for 1 month. Mitochondrial biogenesis and function, apoptosis, and insulin signaling pathway events were studied, primarily in cortical proximal tubules. By electron microscopy analysis, mitochondria were more abundant and more heterogeneous in size, with dense granules in the inner matrix, in Rvs- and Rvs plus EAAm-treated animals. Rvs administration increased protein kinase B and endothelial nitric oxide synthase phosphorylation, but the mammalian target of rapamycin signaling pathway was not affected. Rvs increased the expression of sirtuin 1, peroxisome proliferator-activated receptor γ coactivator-1α, cytochrome oxidase type IV, cytochrome c, and mitochondrial biogenesis markers. Levels of glucose-regulated protein 75 (Grp75), B-cell lymphoma 2, and cyclin-dependent kinase inhibitor 1 were increased in cortical proximal tubules, and expression of the endoplasmic reticulum-mitochondrial chaperone Grp78 was decreased. EAAm supplementation maintained or enhanced these changes. Rvs promotes mitochondrial biogenesis, with a probable anti-apoptotic effect. EAAm boosts these processes and may contribute to the efficient control of cellular energetics and survival in the mouse kidney. This suggests that appropriate nutritional interventions may enhance the beneficial actions of Rvs, and could potentially prevent chronic renal side effects.

Creatine, L-carnitine, and ω3 polyunsaturated fatty acid supplementation from healthy to diseased skeletal muscle

Myopathies are chronic degenerative pathologies that induce the deterioration of the structure and function of skeletal muscle. So far a definitive therapy has not yet been developed and the main aim of myopathy treatment is to slow the progression of the disease. Current nonpharmacological therapies include rehabilitation, ventilator assistance, and nutritional supplements, all of which aim to delay the onset of the disease and relieve its symptoms. Besides an adequate diet, nutritional supplements could play an important role in the treatment of myopathic patients. Here we review the most recent in vitro and in vivo studies investigating the role supplementation with creatine, L-carnitine, and ω3 PUFAs plays in myopathy treatment. Our results suggest that these dietary supplements could have beneficial effects; nevertheless continued studies are required before they could be recommended as a routine treatment in muscle diseases.

Exercise training induces mitochondrial biogenesis and glucose uptake in subcutaneous adipose tissue through eNOS-dependent mechanisms

Insulin resistance and obesity are associated with a reduction of mitochondrial content in various tissues of mammals. Moreover, a reduced nitric oxide (NO) bioavailability impairs several cellular functions, including mitochondrial biogenesis and insulin-stimulated glucose uptake, two important mechanisms of body adaptation in response to physical exercise. Although these mechanisms have been thoroughly investigated in skeletal muscle and heart, few studies have focused on the effects of exercise on mitochondria and glucose metabolism in adipose tissue. In this study, we compared the in vivo effects of chronic exercise in subcutaneous adipose tissue of wild-type (WT) and endothelial NO synthase (eNOS) knockout (eNOS(-/-)) mice after a swim training period. We then investigated the in vitro effects of NO on mouse 3T3-L1 and human subcutaneous adipose tissue-derived adipocytes after a chronic treatment with an NO donor: diethylenetriamine-NO (DETA-NO). We observed that swim training increases mitochondrial biogenesis, mitochondrial DNA content, and glucose uptake in subcutaneous adipose tissue of WT but not eNOS(-/-) mice. Furthermore, we observed that DETA-NO promotes mitochondrial biogenesis and elongation, glucose uptake, and GLUT4 translocation in cultured murine and human adipocytes. These results point to the crucial role of the eNOS-derived NO in the metabolic adaptation of subcutaneous adipose tissue to exercise training.

Muscle uncoupling protein 3 expression is unchanged by chronic ephedrine/caffeine treatment: results of a double blind, randomised clinical trial in morbidly obese females

Ephedrine/caffeine combination (EC) has been shown to induce a small-to-moderate weight loss in obese patients. Several mechanisms have been proposed, among which an increased thermogenic capacity of skeletal muscle consequent to the EC-induced up-regulation of uncoupling protein 3 (UCP3) gene expression. We did a parallel group double-blind, placebo-controlled, 4-week trial to investigate this hypothesis. Thirteen morbidly obese women (25-52 years of age, body-mass index 48.0±4.0 kg/m2, range 41.1-57.6) were randomly assigned to EC (200/20 mg, n = 6) or to placebo (n = 7) administered three times a day orally, before undergoing bariatric surgery. All individuals had an energy-deficit diet equal to about 70% of resting metabolic rate (RMR) diet (mean 5769±1105 kJ/day). The RMR analysed by intention to treat and the UCP3 (long and short isoform) mRNA levels in rectus abdominis were the primary outcomes. Body weight, plasma levels of adrenaline, noradrenaline, triglycerides, free fatty acids, glycerol, TSH, fT4, and fT3 were assessed, as well as fasting glucose, insulin and HOMA index, at baseline and at the end of treatments. Body weight loss was evident in both groups when compared to baseline values (overall -5.2±3.2%, p<0.0001) without significant differences between the treated groups. EC treatment increased the RMR (+9.2±6.8%, p = 0.020), differently from placebo which was linked to a reduction of RMR (-7.6±6.5%, p = 0.029). No significant differences were seen in other metabolic parameters. Notably, no changes of either UCP3 short or UCP3 long isoform mRNA levels were evident between EC and placebo group. Our study provides evidence that 4-week EC administration resulted in a pronounced thermogenic effect not related to muscle UCP3 gene expression and weight loss in morbidly obese females under controlled conditions.

TRIAL REGISTRATION

ClinicalTrials.gov NCT02048215.

Exercise training boosts eNOS-dependent mitochondrial biogenesis in mouse heart: role in adaptation of glucose metabolism

Endurance exercise training increases cardiac energy metabolism through poorly understood mechanisms. Nitric oxide (NO) produced by endothelial NO synthase (eNOS) in cardiomyocytes contributes to cardiac adaptation. Here we demonstrate that the NO donor diethylenetriamine-NO (DETA-NO) activated mitochondrial biogenesis and function, as assessed by upregulated peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α), nuclear respiratory factor 1, and mitochondrial transcription factor A (Tfam) expression, and by increased mitochondrial DNA content and citrate synthase activity in primary mouse cardiomyocytes. DETA-NO also induced mitochondrial biogenesis and function and enhanced both basal and insulin-stimulated glucose uptake in HL-1 cardiomyocytes. The DETA-NO-mediated effects were suppressed by either PGC-1α or Tfam small-interference RNA in HL-1 cardiomyocytes. Wild-type and eNOS(-/-) mice were subjected to 6 wk graduated swim training. We found that eNOS expression, mitochondrial biogenesis, mitochondrial volume density and number, and both basal and insulin-stimulated glucose uptake were increased in left ventricles of swim-trained wild-type mice. On the contrary, the genetic deletion of eNOS prevented all these adaptive phenomena. Our findings demonstrate that exercise training promotes eNOS-dependent mitochondrial biogenesis in heart, which behaves as an essential step in cardiac glucose transport.

Childhood obesity, overweight and underweight: a study in primary schools in Milan

AIMS

The study aims to assess the prevalence of obesity, overweight and underweight in children enrolled in government primary schools (6-11 years of age) in the city of Milan, Italy.

METHODS

One hundred and nine schools were randomly selected for the study. A cross-sectional study was conducted between March and June 2008. A survey was conducted using 16,588 questionnaires completed by parents. Anthropometric data (reported) of both parents and children and information on levels of physical activity and time children spent watching television (TV) were obtained.

RESULTS

In the total sample, parents are predominantly (75.0 %) of normal weight (M: 55.2 %; F: 79.1 %), 16.8 % are overweight (M: 36.9 %; F: 12.6 %), 4.0 % are obese (M: 6.6 %; F: 3.5 %) and 4.2 % are underweight (M: 1.3 %; F: 4.8 %). Among children, 68.7 % are of normal weight (M: 68.2 %; F: 69.2 %), 14.7 % are overweight (M: 15.3 %; F: 14.2 %), 4 % are obese (M: 4.5 %; F: 3.4 %), 11.8 % are underweight (M: 11.2 %; F: 12.5 %) and 0.8 % are severely thin (M: 0.9 %; F: 0.7 %). Children practice physical activity once or twice/week (48.3 %), three to four times/week (38.9 %) or five to seven times/week (8.9 %), while 3.9 % of children do not do any exercise. Most children (85.3 %) watch TV from 30 min to 2 h/day.

CONCLUSION

Contrary to the reported national average, the study shows the presence of only moderate levels of above-average weight and obesity among children. However, it remains important to monitor this phenomenon to raise awareness and to design programs of prevention throughout the country.

(11)C-meta-hydroxyephedrine PET/CT imaging allows in vivo study of adaptive thermogenesis and white-to-brown fat conversion

Several lines of evidence suggest that novel pharmacological approaches aimed at converting white adipose tissue (WAT) into brown adipose tissue (BAT) may represent an effective therapeutic strategy for obesity and related disorders. ((18))F-fluorodeoxyglucose ((18)F-FDG) is the only positron emission tomography (PET) tracer commonly used to study BAT function, and so far no functional tools have been described to investigate in vivo white-to-brown fat conversion. In this report, we show that the PET tracer (11)C-meta-hydroxyephedrine ((11)C-MHED, a norepinephrine analogue) is a useful tool to investigate the sympathetic nervous system (SNS) activity in BAT of lean and dietary obese mice. Moreover, we demonstrate that (11)C-MHED is a specific marker of the SNS-mediated thermogenesis in typical BAT depots, and that this tracer can detect in vivo WAT to BAT conversion.

Role of Insulin and Free Fatty Acids in the Regulation ofobGene Expression and Plasma Leptin in Normal Rats

OBJECTIVE

It is under debate whether free fatty acids (FFAs) play an independent role in the regulation of adipose cell functions. In this study, we evaluated whether leptin secretion induced by FFA is due directly to an increased FFA availability or whether it is mediated by insulin levels.

RESEARCH METHODS AND PROCEDURES

To test this hypothesis, we compared the effects of six different experimental designs, with different FFA and insulin levels, on plasma leptin: euglycemic clamp, euglycemic clamp + FFA infusion, FFA infusion alone, FFA + somatostatin infusion, somatostatin infusion alone, and saline infusion.

RESULTS

Our results showed that euglycemic clamp, FFA infusion, or both in combination induced a similar increment of circulating leptin (3.31 +/- 0.30, 3.40 +/- 0.90, and 3.35 +/- 0.80 ng/mL, respectively). Moreover, the inhibition of FFA-induced insulin increase by means of somatostatin infusion completely abolished the rise of leptin in response to FFA (1.05 +/- 0.30 vs. 3.40 +/- 0.90 ng/mL, p < 0.001).

DISCUSSION

In conclusion, our data showed that the effects of high FFA levels on plasma leptin were mediated by the rise of insulin concentration. These data confirm a major role for insulin in the regulation of leptin secretion from rat adipose tissue and support the hypothesis that leptin secretion is coupled to net triglyceride synthesis in adipose tissue.