L-carnitine exerts a nutrigenomic effect via direct modulation of nuclear receptor signaling in adipocytes, hepatocytes and SKMC, demonstrating its nutritional impact

New evidence for gut-muscle axis: Lactic acid bacteria-induced gut microbiota regulates duck meat flavor

The interaction between gut microbiota and muscles through the gut-muscle axis has received increasing attention. This study attempted to address existing research gaps by investigating the effects of gut microbiota on meat flavor. Specifically, lactic acid bacteria were administered to ducks, and the results of e-nose and e-tongue showed significantly enhanced meat flavor in the treatment group. Further analyses using GC-MS revealed an increase in 6 characteristic volatile flavor compounds, including pentanal, hexanal, heptanal, 1-octen-3-ol, 2,3-octanedione, and 2-pentylfuran. Linoleic acid was identified as the key fatty acid that influences meat flavor. Metagenomic and transcriptomic results further confirmed that cecal microbiota affects the duck meat flavor by regulating the metabolic pathways of fatty acids and amino acids, especially ACACB was related to fatty acid biosynthesis and ACAT2, ALDH1A1 with fatty acid degradation. This study sheds light on a novel approach to improving the flavor of animal-derived food.

Regulation of protein O-GlcNAcylation by circadian, metabolic, and cellular signals

O-linked β-N-acetylglucosamine (O-GlcNAcylation) is a dynamic post-translational modification that regulates thousands of proteins and almost all cellular processes. Aberrant O-GlcNAcylation has been associated with numerous diseases, including cancer, neurodegenerative diseases, cardiovascular diseases, and type 2 diabetes. O-GlcNAcylation is highly nutrient-sensitive since it is dependent on UDP-GlcNAc, the end product of the hexosamine biosynthetic pathway (HBP). We previously observed daily rhythmicity of protein O-GlcNAcylation in a Drosophila model that is sensitive to the timing of food consumption. We showed that the circadian clock is pivotal in regulating daily O-GlcNAcylation rhythms given its control of the feeding-fasting cycle and hence nutrient availability. Interestingly, we reported that the circadian clock also modulates daily O-GlcNAcylation rhythm by regulating molecular mechanisms beyond the regulation of food consumption time. A large body of work now indicates that O-GlcNAcylation is likely a generalized cellular status effector as it responds to various cellular signals and conditions, such as ER stress, apoptosis, and infection. In this review, we summarize the metabolic regulation of protein O-GlcNAcylation through nutrient availability, HBP enzymes, and O-GlcNAc processing enzymes. We discuss the emerging roles of circadian clocks in regulating daily O-GlcNAcylation rhythm. Finally, we provide an overview of other cellular signals or conditions that impact O-GlcNAcylation. Many of these cellular pathways are themselves regulated by the clock and/or metabolism. Our review highlights the importance of maintaining optimal O-GlcNAc rhythm by restricting eating activity to the active period under physiological conditions and provides insights into potential therapeutic targets of O-GlcNAc homeostasis under pathological conditions.

Mitochondria and Brain Disease: A Comprehensive Review of Pathological Mechanisms and Therapeutic Opportunities

Mitochondria play a vital role in maintaining cellular energy homeostasis, regulating apoptosis, and controlling redox signaling. Dysfunction of mitochondria has been implicated in the pathogenesis of various brain diseases, including neurodegenerative disorders, stroke, and psychiatric illnesses. This review paper provides a comprehensive overview of the intricate relationship between mitochondria and brain disease, focusing on the underlying pathological mechanisms and exploring potential therapeutic opportunities. The review covers key topics such as mitochondrial DNA mutations, impaired oxidative phosphorylation, mitochondrial dynamics, calcium dysregulation, and reactive oxygen species generation in the context of brain disease. Additionally, it discusses emerging strategies targeting mitochondrial dysfunction, including mitochondrial protective agents, metabolic modulators, and gene therapy approaches. By critically analysing the existing literature and recent advancements, this review aims to enhance our understanding of the multifaceted role of mitochondria in brain disease and shed light on novel therapeutic interventions.

Targeting PPARs for therapy of atherosclerosis: A review

Atherosclerosis, a chief pathogenic factor of cardiovascular disease, is associated with many factors including inflammation, dyslipidemia, and oxidative stress. Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors and are widely expressed with tissue- and cell-specificity. They control multiple genes that are involved in lipid metabolism, inflammatory response, and redox homeostasis. Given the diverse biological functions of PPARs, they have been extensively studied since their discovery in 1990s. Although controversies exist, accumulating evidence have demonstrated that PPAR activation attenuates atherosclerosis. Recent advances are valuable for understanding the mechanisms of action of PPAR activation. This article reviews the recent findings, mainly from the year of 2018 to present, including endogenous molecules in regulation of PPARs, roles of PPARs in atherosclerosis by focusing on lipid metabolism, inflammation, and oxidative stress, and synthesized PPAR modulators. This article provides information valuable for researchers in the field of basic cardiovascular research, for pharmacologists that are interested in developing novel PPAR agonists and antagonists with lower side effects as well as for clinicians.

The Role of l-Carnitine in Mitochondria, Prevention of Metabolic Inflexibility and Disease Initiation

Mitochondria control cellular fate by various mechanisms and are key drivers of cellular metabolism. Although the main function of mitochondria is energy production, they are also involved in cellular detoxification, cellular stabilization, as well as control of ketogenesis and glucogenesis. Conditions like neurodegenerative disease, insulin resistance, endocrine imbalances, liver and kidney disease are intimately linked to metabolic disorders or inflexibility and to mitochondrial dysfunction. Mitochondrial dysfunction due to a relative lack of micronutrients and substrates is implicated in the development of many chronic diseases. l-carnitine is one of the key nutrients for proper mitochondrial function and is notable for its role in fatty acid oxidation. l-carnitine also plays a major part in protecting cellular membranes, preventing fatty acid accumulation, modulating ketogenesis and glucogenesis and in the elimination of toxic metabolites. l-carnitine deficiency has been observed in many diseases including organic acidurias, inborn errors of metabolism, endocrine imbalances, liver and kidney disease. The protective effects of micronutrients targeting mitochondria hold considerable promise for the management of age and metabolic related diseases. Preventing nutrient deficiencies like l-carnitine can be beneficial in maintaining metabolic flexibility via the optimization of mitochondrial function. This paper reviews the critical role of l-carnitine in mitochondrial function, metabolic flexibility and in other pathophysiological cellular mechanisms.

Effects of L-carnitine supplementation in patients with mild-to-moderate COVID-19 disease: a pilot study

BACKGROUND

The present single-center clinical trial was designed to evaluate the potential benefits of L-carnitine supplementation in patients with COVID-19 disease.

METHODS AND PATIENTS

The study was conducted on 75 patients with mild-to-moderate COVID-19 hospitalized in Shahid Beheshti Hospital-Hamadan, IRAN. The participants were randomly divided into intervention (n = 32) and control groups (n = 43). The control group received their standard hospital treatment only. In addition to standard medications, the intervention group received 3000 mg oral L-carnitine daily in three divided doses for five days. The blood samples were collected and para-clinical parameters were measured at the beginning and end of the treatment. Clinical outcomes were also recorded, and data were analyzed using χ² and t-tests.

RESULTS

Higher means of O2 saturation were observed in the intervention rather than in the control group. Mean erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were significantly lower in the intervention group. Furthermore, mean alkaline phosphatase (ALP) activity and lactate dehydrogenase (LDH) were lower in the intervention group. Also, lower mean serum creatine phosphokinase (CPK) was observed in the intervention group. No significant differences were observed in terms of clinical symptoms; however, six patients (14%) in the control group died due to the complications of COVID-19, while all patients in the intervention group survived.

CONCLUSION

Taken together, L-carnitine can be considered as a drug supplement in patients with COVID-19.

[Carnitine chloride reduces the severity of experimental hyperhomocysteinemia and promotes lactate utilization by mitochondrial fraction of the rat epididymis]

Hyperhomocysteinemia is a risk factor for many diseases, including reproductive disorders in men. L-carnitine is used in medical practice to correct impaired bioenergetic conditions; in patients with idiopathic forms of infertility its effects are associated with improvement of the sperm parameters. However, the effect of exogenous L-carnitine on the level of homocysteine in the gonadal tissues, as a risk factor for impaired fertility, has not been investigated yet. The aim of this study was to investigate activity of bioenergetic enzymes in the epididymal mitochondrial fraction, the dynamics of changes in the cytoplasmic and mitochondrial lactate levels and LDH activity, the total carnitine content, as well as the oxidative status of these cells under conditions of oxidative stress caused by hyperhomocysteinemia, and to assess the effect of carnitine chloride on these parameters under conditions of methionine administration to male Wistar rats. Methionine administration to animals for three weeks at a dose of 3 g/kg, resulted in development of the severe forms of hyperhomocysteinemia with serum homocysteine concentrations exceeding 100 μmol/L. This was accompanied by a decrease in the activity of enzymes involved in the bioenergetic processes of the cell: tissue respiration (succinate dehydrogenase) and oxidative phosphorylation (H+-ATPase) in the epididymal head and tail. The change in lactate metabolism included an increase in its level in both the mitochondrial and cytoplasmic fractions of the epididymal head and mitochondria of the epididymal tail, and also simultaneous statistically significant decrease in LDH activity in the mitochondria and cytoplasm of the epididymal head. In male rats with severe hyperhomocysteinemia, an increase in the activity of mitochondrial SOD accompanied by an increase in the carbonylation of mitochondrial proteins in the head and tail of the epididymis was noted. Modeling of hyperhomocysteinemia under conditions of carnitine chloride of administration led to different reactions of the cells of the studied tissues assayed in the epididymal head and tail homogenate. In the epididymal head, carnitine chloride promoted an increase in the mitochondrial lactate concentration and a decrease in the cytoplasmic lactate concentration, as well as an increase in the LDH activity associated with the mitochondrial fraction. These changes were accompanied by an increase in the activity of H+-ATPase in the epididymal, thus suggesting that carnitine chloride stimulated lactate transport of into the mitochondria and its use as an energy substrate under conditions of oxidative stress caused by hyperhomocysteinemia. In the tail tissues, the changes were protective in nature and were associated with a decrease in the formation of oxidatively modified proteins.

L-Carnitine Tartrate Downregulates the ACE2 Receptor and Limits SARS-CoV-2 Infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been responsible for one of the worst pandemics in modern history. Several prevention and treatment strategies have been designed and evaluated in recent months either through the repurposing of existing treatments or the development of new drugs and vaccines. In this study, we show that L-carnitine tartrate supplementation in humans and rodents led to significant decreases of key host dependency factors, notably angiotensin-converting enzyme 2 (ACE2), transmembrane protease serine 2 (TMPRSS2), and Furin, which are responsible for viral attachment, viral spike S-protein cleavage, and priming for viral fusion and entry. Interestingly, pre-treatment of Calu-3, human lung epithelial cells, with L-carnitine tartrate led to a significant and dose-dependent inhibition of the infection by SARS-CoV-2. Infection inhibition coincided with a significant decrease in ACE2 mRNA expression levels. These data suggest that L-carnitine tartrate should be tested with appropriate trials in humans for the possibility to limit SARS-CoV-2 infection.