Comparative Cerebroprotective Potential of d- and l-Carnosine Following Ischemic Stroke in Mice

Excitotoxic Storms of Ischemic Stroke: A Non-neuronal Perspective

Numerous neurological disorders share a fatal pathologic process known as glutamate excitotoxicity. Among which, ischemic stroke is the major cause of mortality and disability worldwide. For a long time, the main idea of developing anti-excitotoxic neuroprotective agents was to block glutamate receptors. Despite this, there has been little successful clinical translation to date. After decades of "neuron-centered" views, a growing number of studies have recently revealed the importance of non-neuronal cells. Glial cells, cerebral microvascular endothelial cells, blood cells, and so forth are extensively engaged in glutamate synthesis, release, reuptake, and metabolism. They also express functional glutamate receptors and can listen and respond for fast synaptic transmission. This broadens the thoughts of developing excitotoxicity antagonists. In this review, the critical contribution of non-neuronal cells in glutamate excitotoxicity during ischemic stroke will be emphasized in detail, and the latest research progress as well as corresponding therapeutic strategies will be updated at length, aiming to reconceptualize glutamate excitotoxicity in a non-neuronal perspective.

Electrophoretic Determination of L-Carnosine in Health Supplements Using an Integrated Lab-on-a-Chip Platform with Contactless Conductivity Detection

The health supplement industry is one of the fastest growing industries in the world, but there is a lack of suitable analytical methods for the determination of active compounds in health supplements such as peptides. The present work describes an implementation of contactless conductivity detection on microchip technology as a new strategy for the electrophoretic determination of L-carnosine in complex health supplement formulations without pre-concentration and derivatization steps. The best results were obtained in the case of +1.00 kV applied for 20 s for injection and +2.75 kV applied for 260 s for the separation step. Under the selected conditions, a linear detector response of 5 × 10-6 to 5 × 10-5 M was achieved. L-carnosine retention time was 61 s. The excellent reproducibility of both migration time and detector response confirmed the high precision of the method. The applicability of the method was demonstrated by the determination of L-carnosine in three different samples of health supplements. The recoveries ranged from 91 to 105%. Subsequent analysis of the samples by CE-UV-VIS and HPLC-DAD confirmed the accuracy of the obtained results.

NK Cells from Human Cytomegalovirus-Seropositive Individuals Have a Distinct Metabolic Profile That Correlates with Elevated mTOR Signaling

CMV can elicit adaptive immune features in both mouse and human NK cells. Mouse Ly49H+ NK cells expand 100- to 1000-fold in response to mouse CMV infection and persist for months after exposure. Human NKG2C+ NK cells also expand after human CMV (HCMV) infection and persist for months. The clonal expansion of adaptive NK cells is likely an energy-intensive process, and the metabolic requirements that support adaptive NK cell expansion and persistence remain largely uncharacterized. We previously reported that NK cells from HCMV-seropositive donors had increased maximum capacity for both glycolysis and mitochondrial oxidative phosphorylation relative to NK cells from HCMV-seronegative donors. In this article, we report an extension of this work in which we analyzed the metabolomes of NK cells from HCMV-seropositive donors with NKG2C+ expansions and NK cells from HCMV seronegative donors without such expansions. NK cells from HCMV+ donors exhibited striking elevations in purine and pyrimidine deoxyribonucleotides, along with moderate increases in plasma membrane components. Mechanistic target of rapamycin (mTOR) is a serine/threonine protein kinase that, as a part of mTOR complex 1 (mTORC1), bridges nutrient signaling to metabolic processes necessary for cell growth. Signaling through mTORC1 induces both nucleotide and lipid synthesis. We observed elevated mTORC1 signaling on activation in both NKG2C- and NKG2C+ NK cells from HCMV+ donors relative to those from HCMV- donors, demonstrating a correlation between higher mTORC1 activity and synthesis of key metabolites for cell growth and division.

Neuroprotective efficacy of N-t-butylhydroxylamine (NtBHA) in transient focal ischemia in rats

The pharmacological or toxicological activities of the degradation products of drug candidates have been unaddressed during the drug development process. Ischemic stroke accounts for 80% of all strokes and is responsible for considerable mortality and disability worldwide. Despite decades of research on neuroprotective agents, tissue plasminogen activators (t-PA), a thrombolytic agent, remains the only approved acute stroke pharmacological therapy. NXY-059, a free radical scavenger, exhibited striking neuroprotective properties in preclinical models and met all the criteria established by the Stroke Academic Industry Roundtable (STAIR) for a neuroprotective agent. In phase 3 clinical trials, NXY-059 exhibited significant neuroprotective effects in one trial (SAINT-I), but not in the second (SAINT-II). Some have hypothesized that N-t-butyl hydroxylamine (NtBHA), a breakdown product of NXY-059 was the actual neuroprotective agent in SAINT-I and that changes to the formulation of NXY-059 to prevent its breakdown to NtBHA in SAINT -II was the reason for the lack of efficacy. We evaluated the neuroprotective effect of NtBHA in N-methyl-D-aspartate (NMDA)-treated primary neurons and in rat focal cerebral ischemia. NtBHA significantly attenuated infarct volume in rat transient focal ischemia, and attenuated NMDA-induced cytotoxicity in primary cortical neurons. NtBHA also reduced free radical generation and exhibited mitochondrial protection.

Trehalose-Carnosine Prevents the Effects of Spinal Cord Injury Through Regulating Acute Inflammation and Zinc(II) Ion Homeostasis

Spinal cord injury (SCI) leads to long-term and permanent motor dysfunctions, and nervous system abnormalities. Injury to the spinal cord triggers a signaling cascade that results in activation of the inflammatory cascade, apoptosis, and Zn(II) ion homeostasis. Trehalose (Tre), a nonreducing disaccharide, and L-carnosine (Car), (β-alanyl-L-histidine), one of the endogenous histidine dipeptides have been recognized to suppress early inflammatory effects, oxidative stress and to possess neuroprotective effects. We report on the effects of the conjugation of Tre with Car (Tre-car) in reducing inflammation in in vitro and in vivo models. The in vitro study was performed using rat pheochromocytoma cells (PC12 cell line). After 24 h, Tre-car, Car, Tre, and Tre + Car mixture treatments, cells were collected and used to investigate Zn²⁺ homeostasis. The in vivo model of SCI was induced by extradural compression of the spinal cord at the T6-T8 levels. After treatments with Tre, Car and Tre-Car conjugate 1 and 6 h after SCI, spinal cord tissue was collected for analysis. In vitro results demonstrated the ionophore effect and chelating features of L-carnosine and its conjugate. In vivo, the Tre-car conjugate treatment counteracted the activation of the early inflammatory cascade, oxidative stress and apoptosis after SCI. The Tre-car conjugate stimulated neurotrophic factors release, and influenced Zn²⁺ homeostasis. We demonstrated that Tre-car, Tre and Car treatments improved tissue recovery after SCI. Tre-car decreased proinflammatory, oxidative stress mediators release, upregulated neurotrophic factors and restored Zn²⁺ homeostasis, suggesting that Tre-car may represent a promising therapeutic agent for counteracting the consequences of SCI.

Fecal Microbiota Transplantation Exerts Neuroprotective Effects in a Mouse Spinal Cord Injury Model by Modulating the Microenvironment at the Lesion Site

The primary traumatic event that causes spinal cord injury (SCI) is followed by a progressive secondary injury featured by vascular disruption and ischemia, inflammatory responses and the release of cytotoxic debris, which collectively add to the hostile microenvironment of the lesioned cord and inhibit tissue regeneration and functional recovery. In a previous study, we reported that fecal microbiota transplantation (FMT) promotes functional recovery in a contusion SCI mouse model; yet whether and how FMT treatment may impact the microenvironment at the injury site are not well known. In the current study, we examined individual niche components and investigated the effects of FMT on microcirculation, inflammation and trophic factor secretion in the spinal cord of SCI mice. FMT treatment significantly improved spinal cord tissue sparing, vascular perfusion and pericyte coverage and blood-spinal cord-barrier (BSCB) integrity, suppressed the activation of microglia and astrocytes, and enhanced the secretion of neurotrophic factors. Suppression of inflammation and upregulation of trophic factors, jointly, may rebalance the niche homeostasis at the injury site and render it favorable for reparative and regenerative processes, eventually leading to functional recovery. Furthermore, microbiota metabolic profiling revealed that amino acids including β-alanine constituted a major part of the differentially detected metabolites between the groups. Supplementation of β-alanine in SCI mice reduced BSCB permeability and increased the number of surviving neurons, suggesting that β-alanine may be one of the mediators of FMT that participates in the modulation and rebalancing of the microenvironment at the injured spinal cord. IMPORTANCE FMT treatment shows a profound impact on the microenvironment that involves microcirculation, blood-spinal cord-barrier, activation of immune cells, and secretion of neurotrophic factors. Analysis of metabolic profiles reveals around 22 differentially detected metabolites between the groups, and β-alanine was further chosen for functional validation experiments. Supplementation of SCI mice with β-alanine significantly improves neuronal survival, and the integrity of blood-spinal cord-barrier at the lesion site, suggesting that β-alanine might be one of the mediators following FMT that has contributed to the recovery.

The Potential Use of Carnosine in Diabetes and Other Afflictions Reported in Long COVID Patients

Carnosine is a dipeptide expressed in both the central nervous system and periphery. Several biological functions have been attributed to carnosine, including as an anti-inflammatory and antioxidant agent, and as a modulator of mitochondrial metabolism. Some of these mechanisms have been implicated in the pathophysiology of coronavirus disease-2019 (COVID-19). COVID-19 is caused by severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2). The clinical manifestation and recovery time for COVID-19 are variable. Some patients are severely affected by SARS-CoV-2 infection and may experience respiratory failure, thromboembolic disease, neurological symptoms, kidney damage, acute pancreatitis, and even death. COVID-19 patients with comorbidities, including diabetes, are at higher risk of death. Mechanisms underlying the dysfunction of the afflicted organs in COVID-19 patients have been discussed, the most common being the so-called cytokine storm. Given the biological effects attributed to carnosine, adjuvant therapy with this dipeptide could be considered as supportive treatment in patients with either COVID-19 or long COVID.

Carnosine suppresses human colorectal cancer cell proliferation by inducing necroptosis and autophagy and reducing angiogenesis

Carnosine (β-alanyl-L-histidine) is found in beef and fish. The present study aimed to investigate the effects of carnosine on the cell proliferation of human colorectal cancer cells. After human colorectal cancer HCT-116 cells were treated carnosine for 72 or 96 h, the cell proliferation, apoptosis, autophagy, necroptosis, angiogenesis and the expression of related regulatory molecules were detected using MTT assays, fluorescence image analysis and RT-qPCR in this study. Treatment of HCT-116 cells with 5, 10 or 15 mM carnosine for 72 or 96 h significantly decreased cell viability (P<0.05). The mRNA expression of β-catenin and transcription factor 4 (Tcf-4) was significantly reduced by 15–23% and 11–80%, respectively (P<0.05). When HCT-116 cells were treated with 15 mM carnosine, the mRNA levels of 1A/1B-light chain 3 and phosphatidylinositol 3-kinase were significantly increased by 235% and 249%, respectively (P<0.05). The mRNA level of Beclin-1 and autophagy levels were significantly increased by 137–141% in HCT-116 cells treated with 5, 10 or 15 mM carnosine (P<0.05). Carnosine (15 mM) also increased reactive oxygen species levels and mixed lineage kinase domain-like protein mRNA expression and depleted ATP levels (P<0.05). The angiogenesis-regulating molecules vascular endothelial growth factor, epidermal growth factor receptor and hypoxia-inducible factor 1-α were all significantly decreased by 10 or 15 mM carnosine treatment. These results showed that carnosine could suppress human colorectal cell proliferation by reducing β-catenin/Tcf-4 signaling, inducing autophagy and necroptosis and inhibiting angiogenesis. It was demonstrated that carnosine is a potential compound from dietary food for the future clinical treatment and/or prevention of colorectal cancer.

Ionophore Ability of Carnosine and Its Trehalose Conjugate Assists Copper Signal in Triggering Brain-Derived Neurotrophic Factor and Vascular Endothelial Growth Factor Activation In Vitro

l-carnosine (β-alanyl-l-histidine) (Car hereafter) is a natural dipeptide widely distributed in mammalian tissues and reaching high concentrations (0.7-2.0 mM) in the brain. The molecular features of the dipeptide underlie the antioxidant, anti-aggregating and metal chelating ability showed in a large number of physiological effects, while the biological mechanisms involved in the protective role found against several diseases cannot be explained on the basis of the above-mentioned properties alone, requiring further research efforts. It has been reported that l-carnosine increases the secretion and expression of various neurotrophic factors and affects copper homeostasis in nervous cells inducing Cu cellular uptake in keeping with the key metal-sensing system. Having in mind this l-carnosine ability, here we report the copper-binding and ionophore ability of l-carnosine to activate tyrosine kinase cascade pathways in PC12 cells and stimulate the expression of BDNF. Furthermore, the study was extended to verify the ability of the dipeptide to favor copper signaling inducing the expression of VEGF. Being aware that the potential protective action of l-carnosine is drastically hampered by its hydrolysis, we also report on the behavior of a conjugate of l-carnosine with trehalose that blocks the carnosinase degradative activity. Overall, our findings describe a copper tuning effect on the ability of l-carnosine and, particularly its conjugate, to activate tyrosine kinase cascade pathways.

Clinical Efficacy and Safety of Non-Cross-Linked Hyaluronic Acid Combined with L-carnosine for Horizontal Neck Wrinkles Treatment

Background Horizontal neck wrinkle formation is gaining more attention among cosmetic practitioners and clients. To date, hyaluronic acid products are one of the most common treatment options for this aesthetic concern. However, different therapeutic strategies should be given to solve the problem due to multiple etiological reasons. Given that oxidative damage plays a critical role in neck wrinkle formation, anti-oxidative compounds are now considered by physicians when making a treatment plan. Aims To evaluate the efficacy and safety of a non-cross-linked hyaluronic acid filler in combination with L-carnosine in treating horizontal neck wrinkles. Methods Thirteen patients with a Wrinkle Assessment Scale (WAS) of 2–5 for horizontal neck wrinkles were treated with L-carnosine-containing non-cross-linked hyaluronic acid. Participants were followed-up for 3 months after treatment. The post-treated WAS scores evaluated by physicians were collected when patient satisfaction was surveyed. Any post-treatment adverse events were recorded. Results With a single injection of the above filler, the physician-evaluated WAS scores improved by at least one score at one month and the improvement kept consistent as far as three months after injection. According to the last follow-up visit, 11/13 patients were satisfied with the treatment effect of their neck wrinkle. Moreover, adverse events were rare after filler injection, except for local complications that were considered common reactions to the filler injection procedure. Conclusion The non-cross-linked hyaluronic acid filler containing L-carnosine is safe and effective for treating horizontal neck wrinkles.

Level of Evidence IV This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.