Protective effect of L-carnitine against H(2)O(2)-induced neurotoxicity in neuroblastoma (SH-SY5Y) cells

Effects of L-Carnitine Intake on Exercise-Induced Muscle Damage and Oxidative Stress: A Narrative Scoping Review

Exercise-induced muscle damage results in decreased physical performance that is accompanied by an inflammatory response in muscle tissue. The inflammation process occurs with the infiltration of phagocytes (neutrophils and macrophages) that play a key role in the repair and regeneration of muscle tissue. In this context, high intensity or long-lasting exercise results in the breakdown of cell structures. The removal of cellular debris is performed by infiltrated phagocytes, but with the release of free radicals as collateral products. L-carnitine is a key metabolite in cellular energy metabolism, but at the same time, it exerts antioxidant actions in the neuromuscular system. L-carnitine eliminates reactive oxygen and nitrogen species that, in excess, alter DNA, lipids and proteins, disturbing cell function. Supplementation using L-carnitine results in an increase in serum L-carnitine levels that correlates positively with the decrease in cell alterations induced by oxidative stress situations, such as hypoxia. The present narrative scoping review focuses on the critical evaluation of the efficacy of L-carnitine supplementation on exercise-induced muscle damage, particularly in postexercise inflammatory and oxidative damage. Although both concepts appear associated, only in two studies were evaluated together. In addition, other studies explored the effect of L-carnitine in perception of fatigue and delayed onset of muscle soreness. In view of the studies analyzed and considering the role of L-carnitine in muscle bioenergetics and its antioxidant potential, this supplement could help in postexercise recovery. However, further studies are needed to conclusively clarify the mechanisms underlying these protective effects.

Clinical Evidence of Acetyl-L-Carnitine Efficacy in the Treatment of Acute Ischemic Stroke: A Pilot Clinical Trial

Background. This study was undertaken to evaluate the influence of oral Acetyl-L-carnitine (ALC) in patients with acute ischemic stroke. Methods. Sixty-nine cases with acute ischemic stroke with the onset of symptoms less than 24 hours not candidates for reperfusion therapy were randomly assigned to either the ALC group (1000 mg three times per day for three consecutive days) or the matching placebo group. The study outcomes based on intention-to-treat criteria included the change in the modified Rankin Scale (mRS) and National Institutes of Health Stroke Scale (NIHSS) score from baseline to day 90, as well as the change in serum levels of the inflammatory and oxidative stress biomarkers over the 3-day treatment protocol. Results. The NIHSS score and mRS score on day 90 were improved by 5.82 and 0.94 scores, respectively, in the ALC-treated group compared to 2.83 and 0.11 scores, respectively, in the placebo-treated group, which demonstrated the superiority of ALC relative to placebo. By using the multivariable analysis after adjusting for other variables in the model, compared to the group treated with placebo, patients in the ALC group had lower NIHSS score ( $\beta$ : -2.40, 95% CI: -0.69, -4.10 ( $p=0.007$ )) and mRS score ( $\beta$ : -1.18, 95% CI: -0.52, -1.84 ( $p=0.001$ )) 90 days after the intervention. The percentage of patients with a favourable functional outcome at day 90, defined as mRS scores of 0 or 1, was significantly higher in the ALC group in comparison to the placebo group (52.9% versus 28.6%). Further, over the 3-day treatment protocol, in the patients receiving ALC, the serum levels of proinflammatory biomarkers, including soluble intercellular adhesion molecule-1 (sICAM-1), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), and neuron-specific enolase (NSE), showed a significant decrease, while the serum levels of antioxidant biomarkers, including glutathione peroxidase (GPx), superoxide dismutase (SOD), and total antioxidant capacity (TAC), as well as the total L-carnitine’s level showed a significant increase compared to those in patients receiving placebo indicating significant alteration. Conclusions. Although preliminary, these results suggested that ALC administration during the acute phase of ischemic stroke might be helpful in improving functional and neurological outcomes that are probably linked to its anti-inflammatory and antioxidant properties. Trial Registration. This trial is registered with IRCT20150629022965N17 at Iranian Registry of Clinical Trials (registration date: 25/07/2018).

The Neuroprotective Effect of L-Carnitine against Glyceraldehyde-Induced Metabolic Impairment: Possible Implications in Alzheimer's Disease

Alzheimer’s disease (AD) is a neurodegenerative disorder characterized by progressive cognitive regression and memory loss. Dysfunctions of both glucose metabolism and mitochondrial dynamics have been recognized as the main upstream events of the degenerative processes leading to AD. It has been recently found that correcting cell metabolism by providing alternative substrates can prevent neuronal injury by retaining mitochondrial function and reducing AD marker levels. Here, we induced an AD-like phenotype by using the glycolysis inhibitor glyceraldehyde (GA) and explored whether L-carnitine (4-N-trimethylamino-3-hydroxybutyric acid, LC) could mitigate neuronal damage, both in SH-SY5Y neuroblastoma cells and in rat primary cortical neurons. We have already reported that GA significantly modified AD marker levels; here we demonstrated that GA dramatically compromised cellular bioenergetic status, as revealed by glycolysis and oxygen consumption rate (OCR) evaluation. We found that LC ameliorated cell survival, improved OCR and ATP synthesis, prevented the loss of the mitochondrial membrane potential (Δψ_m) and reduced the formation of reactive oxygen species (ROS). Of note, the beneficial effect of LC did not rely on the glycolytic pathway rescue. Finally, we noticed that LC significantly reduced the increase in pTau levels induced by GA. Overall, these findings suggest that the use of LC can promote cell survival in the setting of the metabolic impairments commonly observed in AD. Our data suggest that LC may act by maintaining mitochondrial function and by reducing the pTau level.

Significance of Levocarnitine Treatment in Dialysis Patients

Carnitine is a naturally occurring amino acid derivative that is involved in the transport of long-chain fatty acids to the mitochondrial matrix. There, these substrates undergo β-oxidation, producing energy. The major sources of carnitine are dietary intake, although carnitine is also endogenously synthesized in the liver and kidney. However, in patients on dialysis, serum carnitine levels progressively fall due to restricted dietary intake and deprivation of endogenous synthesis in the kidney. Furthermore, serum-free carnitine is removed by hemodialysis treatment because the molecular weight of carnitine is small (161 Da) and its protein binding rates are very low. Therefore, the dialysis procedure is a major cause of carnitine deficiency in patients undergoing hemodialysis. This deficiency may contribute to several clinical disorders in such patients. Symptoms of dialysis-related carnitine deficiency include erythropoiesis-stimulating agent-resistant anemia, myopathy, muscle weakness, and intradialytic muscle cramps and hypotension. However, levocarnitine administration might replenish the free carnitine and help to increase carnitine levels in muscle. This article reviews the previous research into levocarnitine therapy in patients on maintenance dialysis for the treatment of renal anemia, cardiac dysfunction, dyslipidemia, and muscle and dialytic symptoms, and it examines the efficacy of the therapeutic approach and related issues.

Effect of L-carnitine on the expression of the apoptotic genes Bcl-2 and Bax

OBJECTIVE

The genes Bcl-2 and Bax play important roles in apoptosis. Many studies have shown that formalin has a strong deleterious effect on male fertility and can induce apoptosis. L-carnitine has been reported to potentially reverse the negative effects of formalin, leading to improved spermatogenesis. In this study, we examined the levels of expression of Bcl-2 and Bax in mice treated with formalin and L-carnitine.

METHODS

Thirty adult BALB/c mice were categorized into three groups. The mice in the control group (n=10) were not injected with any substance. The mice in the second group (n=10) received 10 mg/kg of formalin daily via an intraperitoneal injection, while those in the final group (n=10) were intraperitoneally injected daily with a dose of 10 mg/kg of formalin and 100 mg/kg of L-carnitine. All mice were kept in isolated cages for 31 days.

RESULTS

The expression of Bax was significantly higher in the formalin-treated mice than in the mice of the control group, while the expression of Bcl-2 was significantly lower in the formalin-treated mice than in the control mice. Additionally, relative to control mice, Bcl-2 expression increased and Bax expression decreased in the mice administered both formalin and L-carnitine.

CONCLUSION

In this study, L-carnitine was shown to augment Bcl-2 expression and to reduce Bax expression, indicating that this compound may inhibit apoptosis. Due to its positive effects, L-carnitine can be used as a prophylactic treatment for people who routinely come into direct contact with formalin as an occupational hazard.

Genome-Protecting Compounds as Potential Geroprotectors

Throughout life, organisms are exposed to various exogenous and endogenous factors that cause DNA damages and somatic mutations provoking genomic instability. At a young age, compensatory mechanisms of genome protection are activated to prevent phenotypic and functional changes. However, the increasing stress and age-related deterioration in the functioning of these mechanisms result in damage accumulation, overcoming the functional threshold. This leads to aging and the development of age-related diseases. There are several ways to counteract these changes: 1) prevention of DNA damage through stimulation of antioxidant and detoxification systems, as well as transition metal chelation; 2) regulation of DNA methylation, chromatin structure, non-coding RNA activity and prevention of nuclear architecture alterations; 3) improving DNA damage response and repair; 4) selective removal of damaged non-functional and senescent cells. In the article, we have reviewed data about the effects of various trace elements, vitamins, polyphenols, terpenes, and other phytochemicals, as well as a number of synthetic pharmacological substances in these ways. Most of the compounds demonstrate the geroprotective potential and increase the lifespan in model organisms. However, their genome-protecting effects are non-selective and often are conditioned by hormesis. Consequently, the development of selective drugs targeting genome protection is an advanced direction.

Protective Effects of the Soluble Epoxide Hydrolase Inhibitor 1-Trifluoromethoxyphenyl-3-(1-Propionylpiperidin-4-yl) Urea in a Rat Model of Permanent Middle Cerebral Artery Occlusion

Acute ischemic stroke is a serious disease that endangers human health. In our efforts to develop an effective therapy, we previously showed that the potent, highly selective inhibitor of soluble epoxide hydrolase called 1-trifuoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU) protects the brain against focal ischemia in rats. Here we explored the mechanism of TPPU action by assessing whether it could preserve blood-brain barrier integrity and reduce apoptosis in the brain during permanent middle cerebral artery occlusion in male Sprague-Dawley rats. TPPU administration at the onset of stroke and once daily thereafter led to smaller infarct volume and brain edema as well as milder neurological deficits. TPPU significantly inhibited the activity of soluble epoxide hydrolase and matrix metalloproteases 2 and 9, reducing 14,15-DHET levels, while increasing expression of tight junction proteins. TPPU decreased numbers of apoptotic cells by down-regulating the pro-apoptotic proteins BAX and Caspase-3, while up-regulating the anti-apoptotic protein BCL-2. Our results suggest that TPPU can protect the blood-brain barrier and reduce the apoptosis of brain tissue caused by ischemia.

Exogenous L-Carnitine Promotes Plant Growth and Cell Division by Mitigating Genotoxic Damage of Salt Stress

L-carnitine is a fundamental ammonium compound responsible for energy metabolism in all living organisms. It is an oxidative stress regulator, especially in bacteria and yeast and lipid metabolism in plants. Besides its metabolic functions, l-carnitine has detoxification and antioxidant roles in the cells. Due to the complex interrelationship of l-carnitine between lipid metabolism and salinity dependent oxidative stress, this study investigates the exogenous l-carnitine (1 mM) function on seed germination, cell division and chromosome behaviour in barley seeds (Hordeum vulgare L. cv. Bulbul-89) under different salt stress concentrations (0, 0.25, 0.30 and 0.35 M). The present work showed that l-carnitine pretreatment could not be successful to stimulate cell division on barley seeds under non-stressed conditions compared to stressed conditions. Depending on increasing salinity without pretreatment with l-carnitine, the mitotic index significantly decreased in barley seeds. Pretreatment of barley seeds with l-carnitine under salt stress conditions was found promising as a plant growth promoter and stimulator of mitosis. In addition, pretreatment of barley seeds with l-carnitine alleviated detrimental effects of salt stress on chromosome structure and it protected cells from the genotoxic effects of salt. This may be caused by the antioxidant and protective action of the l-carnitine. Consequently, this study demonstrated that the exogenous application of 1 mM l-carnitine mitigates the harmful effects of salt stress by increasing mitosis and decreasing DNA damage caused by oxidative stress on barley seedlings.

L-Carnitine-Mediated Tumor Cell Protection and Poor Patient Survival Associated with OCTN2 Overexpression in Glioblastoma Multiforme

PURPOSE

Apoptotic dysregulation, redox adaptive mechanisms, and resilience to hypoxia are major causes of glioblastoma (GBM) resistance to therapy. Commonly known as crucial factors in energy metabolism, OCTN2 (SLC22A5) and its substrate L-carnitine (LC) are increasingly recognized as actors in cytoprotection. This study provides a comprehensive expression and survival analysis of the OCTN2/LC system in GBM and clarifies the system's impact on GBM progression.

EXPERIMENTAL DESIGN

OCTN2 expression and LC content were measured in 121 resected human GBM specimens and 10 healthy brain samples and analyzed for prognostic significance. Depending on LC administration, the effects of hypoxic, metabolic, and cytotoxic stress on survival and migration of LN18 GBM cells were further studied in vitro. Finally, an orthotopic mouse model was employed to investigate inhibition of the OCTN2/LC system on in vivo GBM growth.

RESULTS

Compared with healthy brain, OCTN2 expression was increased in primary and even more so in recurrent GBM on mRNA and protein level. High OCTN2 expression was associated with a poor overall patient survival; the unadjusted HR for death was 2.7 (95% CI, 1.47-4.91; P < 0.001). LC administration to GBM cells increased their tolerance toward cytotoxicity, whereas siRNA-mediated OCTN2 silencing led to a loss of tumor cell viability. In line herewith, OCTN2/LC inhibition by meldonium resulted in reduced tumor growth in an orthotopic GBM mouse model.

CONCLUSIONS

Our data indicate a potential role of the OCTN2/LC system in GBM progression and resistance to therapy, and suggests OCTN2 as a prognostic marker in patients with primary GBM.

Protective effects of 2-(2-benzonfuranyl)-2-imidazoline combined with tissue plasminogen activator after embolic stroke in rats

Stroke is the third leading cause of death and disability in developing countries. The effective therapy for acute ischemic stroke is thrombolysis with recombinant tissue plasminogen activator (rt-PA) within 4.5 h of stroke onset. An effective post-ischemic neuroprotectant would extend the advantages of rt-PA, and protect against complications of thrombolysis. We previously reported that 2-(2-benzofuranyl)-2-imidazoline (2-BFI), a newly discovered ligand for high-affinity type 2 imidazoline receptor (I2R), provides neuroprotection against ischemic stroke in rats. Here we investigated the protective effects of 2-BFI in combination with delayed intravenous rt-PA after stroke induced by embolic middle cerebral artery occlusion (eMCAO) in rats. Infarct size was determined using 2,3,5-triphenyltrazolium chloride staining, while neurological deficit was assessed based on neurological score. Numbers of apoptotic cells in vivo were estimated using TUNEL stain, and expression of the pro-apoptotic protein BAX and anti-apoptotic protein BCL-2 were quantified by Western blotting. The results showed that 2-BFI (3 mg/kg) administered at 0.5 h after embolic MCAO combined with rt-PA (10 mg/kg) administered at 6 h reduced brain infarct size, mitigated neurological deficit, decreased the number of TUNEL-positive cells, down-regulated BAX expression, and up-regulated BCL-2 expression. These findings suggest that 2-BFI may extend the therapeutic window of rt-PA to 6 h after embolic stroke onset in rats.

Ziram Delays Pubertal Development of Rat Leydig Cells

Ziram [zinc, bis (dimethyldithiocarbamate)] is an agricultural dithiocarbamate fungicide. By virtual screening, we have identified that ziram is a potential endocrine disruptor. To investigate its effects on pubertal development of Leydig cells, 35-day-old male Sprague Dawley rats orally received ziram (2 or 4 mg/kg/d) for 4 weeks and immature Leydig cells isolated from 35-day-old rat testes were treated with ziram (0.5-50 μM in vitro). Serum hormones, Leydig cell number and specific gene or protein expression levels after in vivo treatment were determined and medium androgen levels were measured as well as apoptosis of Leydig cells after in vitro treatment were determined. In vivo exposure to ziram lowered testosterone and follicle-stimulating hormone levels, and reduced Leydig cell number, and downregulated Leydig cell specific gene or protein expression levels. Ziram exposure in vitro inhibited androgen production and steroidogenic enzyme activities in Leydig cells by downregulating expression levels of P450 cholesterol side cleavage enzyme (Cyp11a1), 3β-hydroxysteroid dehydrogenase 1 (Hsd3b1), 17α-hydroxylase/17,20-lyase (Cyp17a1), and 17β-hydroxysteroid dehydrogenase 3 (Hsd17b3) via downregulating the steroidogenic factor 1 (Nr5a1) at a concentration as low as 5 μM. In conclusion, ziram exposure disrupts Leydig cell development during puberty possibly via downregulating Nr5a1.

Induced pluripotent stem cell-derived conditional medium promotes Leydig cell anti-apoptosis and proliferation via autophagy and Wnt/β-catenin pathway

Leydig cell transplantation is a better alternative in the treatment of androgen-deficient males. The main purpose of this study was to investigate the effects of induced pluripotent stem cell-derived conditioned medium (iPS-CM) on the anti-apoptosis, proliferation and function of immature Leydig cells (ILCs), and illuminate the underlying mechanisms. ILCs were exposed to 200 μmol/L hydrogen peroxide (H2 O2 ) for 24 hours with or without iPS-CM treatments. Cell apoptosis was detected by flow cytometric analysis. Cell proliferation was assessed using cell cycle assays and EdU staining. The steroidogenic enzyme expressions were quantified with Western blotting. The results showed that iPS-CM significantly reduced H2 O2 -induced ILC apoptosis through down-regulation of autophagic and apoptotic proteins LC3-I/II, Beclin-1, P62, P53 and BAX as well as up-regulation of BCL-2, which could be inhibited by LY294002 (25 μmol/L). iPS-CM could also promote ILC proliferation through up-regulation of β-catenin and its target proteins cyclin D1, c-Myc and survivin, but was inhibited by XAV939 (10 μmol/L). The level of bFGF in iPS-CM was higher than that of DMEM-LG. Exogenous bFGF (20 ng/mL) or Wnt signalling agonist lithium chloride (LiCl) (20 mmol/L) added into DMEM-LG could achieve the similar effects of iPS-CM. Meanwhile, iPS-CM could improve the medium testosterone levels and up-regulation of LHCGR, SCARB1, STAR, CYP11A1, HSD3B1, CYP17A1, HSD17B3 and SF-1 in H2 O2 -induced ILCs. In conclusion, iPS-CM could reduce H2 O2 -induced ILC apoptosis through the activation of autophagy, promote proliferation through up-regulation of Wnt/β-catenin pathway and enhance testosterone production through increasing steroidogenic enzyme expressions, which might be used in regenerative medicine for future.

L-carnitine contributes to enhancement of neurogenesis from mesenchymal stem cells through Wnt/β-catenin and PKA pathway

The identification of factors capable of enhancing neurogenesis has great potential for cellular therapies in neurodegenerative diseases. Multiple studies have shown the neuroprotective effects of L-carnitine (LC). This study determined whether neuronal differentiation of rat adipose tissue-derived mesenchymal stem cells (ADSCs) can be activated by LC. In this study, protein kinase A (PKA) and Wnt/β-catenin pathways were detected to show if this activation was due to these pathways. The expression of LC-induced neurogenesis markers in ADSCs was characterized using real-time PCR. ELISA was conducted to assess the expression of cyclic adenosine monophosphate (cAMP) and PKA. The expression of β-catenin, reduced dickkopf1 (DKK1), low-density lipoprotein receptor-related protein 5 (LRP5), Wnt1, and Wnt3a genes as Wnt/β-catenin signaling members were used to detect the Wnt/β-catenin pathway. It was observed that LC could promote neurogenesis in ADSCs as well as expression of some neurogenic markers. Moreover, LC causes to increase the cAMP levels and PKA activity. Treatment of ADSCs with H-89 (dihydrochloride hydrate) as PKA inhibitor significantly inhibited the promotion of neurogenic markers, indicating that the PKA signaling pathway could be involved in neurogenesis induction. Analyses of real-time PCR data showed that the mRNA expressions of β-catenin, DKK1, LRP5c-myc, Wnt1, and Wnt3a were increased in the presence of LC. Therefore, the present study showed that LC promotes ADSCs neurogenesis and the LC-induced neurogenic markers could be due to both the PKA and Wnt/β-catenin signaling pathway. Impact statement Neural tissue has long been believed as incapable of regeneration and the identification of cell types and factors capable of neuronal differentiation has generated intense interest. Mesenchymal stem cells (MSCs) are considered as potential targets for stem cell-based therapy. L-carnitin (LC) as an antioxidant may have neuroprotective effects in oxidative damage and possibly in neurodegenerative disorders. We have tried to evaluate the effect of LC as an antioxidant on the neurogenic differentiation of ADSCs in order to further elucidate the simultaneous effects on the capability of the neural regeneration. In this study, PKA and Wnt/β-catenin signaling pathways were detected to see if LC could also activate these pathways. The results of this study showed that 200 µM LC promoted ADSCs neurogenic differentiation, and that it was correlated with the PKA and Wnt/β-catenin signaling pathways.

Potential therapeutic role of L-carnitine in skeletal muscle oxidative stress and atrophy conditions

The targeting of nutraceutical treatment to skeletal muscle damage is an emerging area of research, driven by the need for new therapies for a range of muscle-associated diseases. L-Carnitine (CARN) is an essential nutrient and plays a key role in mitochondrial β-oxidation and in the ubiquitin-proteasome system regulation. As a dietary supplement to improve athletic performance, CARN has been studied for its potential to enhance β-oxidation. However, CARN effects on myogenesis, mitochondrial activity, and hypertrophy process are not completely elucidated. This in vitro study aims to investigate CARN role on skeletal muscle remodeling, differentiation process, and myotubes formation. We analyzed muscle differentiation and morphological features in C2C12 myoblasts exposed to 5 mM CARN. Our results showed that CARN was able to accelerate C2C12 myotubes formation and induce morphological changes, characterizing the start of hypertrophy process. In addition, CARN improved AKT activation and downstream cellular signaling pathways involved in skeletal muscle atrophy process prevention. Also, CARN positively regulated the pathways involved in oxidative stress defense. In this work, we provide an interesting novel mechanism of the potential therapeutic use of CARN to treat pathological conditions characterized by skeletal muscle morphological and functional impairment, oxidative stress production, and atrophy process in aging.

Protective effect of tomatine against hydrogen peroxide-induced neurotoxicity in neuroblastoma (SH-SY5Y) cells

OBJECTIVES

Reactive oxygen species can induce cell apoptosis, and oxidative stress has been implicated in a variety of neurodegenerative disorders. Tomatine, which is a naturally occurring steroidal glycoalkaloid isolated from Solanum cathayanum, has shown potent anti-oxidant properties.

METHODS

In this study, we used the SH-SY5Y cell line as an in vitro model and investigated the protective effect of tomatine against hydrogen peroxide (H2 O2 )-induced neurotoxicity in SH-SY5Y cells.

KEY FINDINGS

Tomatine might inhibit the release of cellular lactate dehydrogenase, increase anti-oxidant enzyme activity and glutathione content, reverse the downregulated protein expression of the brain-derived neurotrophic factor (BDNF), inhibit expression of Bax and activations of caspase-3 and caspase-9 in H2 O2 -induced SH-SY5Y cells.

CONCLUSIONS

Tomatine exerted beneficially neuroprotective effect on H2 O2 -induced SH-SY5Y cells, mainly enhancing intracellular anti-oxidant enzyme activity and BDNF expression, inhibiting H2 O2 -induced oxidative stress as well as expression of Bax and activations of caspase-3 and caspase-9, alleviating H2 O2 -induced SH-SY5Y cell injury and cell death.

Effect of L-carnitine therapy on patients in maintenance hemodialysis: a systematic review and meta-analysis

BACKGROUND

L-Carnitine has been used as adjuvant therapy in hemodialysis (HD) patients for many years. However, there is controversy whether L-carnitine supplementation is beneficial. Therefore we performed a meta-analysis of randomized controlled trials (RCTs) to assess the effect of L-carnitine on HD patients.

METHODS

RCTs of L-carnitine versus placebo for HD patients were searched from Medline, EMBASE and the Cochrane Central Register of Controlled Trials. We screened relevant studies according to predefined inclusion and exclusion criteria, and performed meta-analyses using Revman 5.1 software.

RESULTS

Meta-analysis showed L-carnitine could not increase the total score of 36-item Short-Form Health Survey Questionnaire (SF-36) (SMD 0.76, 95 % CI -0.13 to 1.65, P = 0.09), and L-carnitine therapy did not improve serum C-reactive protein (SMD -0.37, 95 % CI -0.88 to 0.14, P = 0.16), oxidized low-density lipoprotein (SMD 0.04, 95 % CI -0.43 to 0.50, P = 0.87), albumin (SMD 0.25, 95 % CI -0.31 to 0.81, P = 0.38;), hemoglobin (SMD 0.23, 95 % CI -0.23 to 0.68, P = 0.33), cholesterol (SMD -0.24, 95 % CI -0.71 to 0.24, P = 0.33), triglycerides (SMD 0.02, 95 % CI -0.4 to 0.44, P = 0.91) or parathyroid hormone (SMD 0.21, 95 % CI -0.35 to 0.76, P = 0.46) levels.

CONCLUSIONS

There is no evidence that L-carnitine can improve the inflammation, oxidative stress, nutrition, anemia, dyslipidemia, hyperparathyroidism status or quality of life in HD patients. However, given methodological limitations and lack of hard endpoints, high-quality, long-term randomized trials are required to fully elucidate the clinical value of L-carnitine administration in hemodialysis patients.

Photo-activated porphyrin in combination with antibiotics: therapies against Staphylococci

Staphylococcal infections have become difficult to treat due to antibiotic insensitivity and resistance. Antimicrobial combination therapies may minimize acquisition of resistance and photodynamic therapy is an attractive candidate for these combinations. In this manuscript, we explore combined use of antibiotics and meso-tetra (4-aminophenyl) porphine (TAPP), a cationic porphyrin, for treatment of Staphylococcus aureus contamination. We characterize the antimicrobial activity of photoactivated TAPP and show that activity is largely lost in the presence of a radical scavenger. Importantly, TAPP can be reactivated with continued, albeit attenuated, antibacterial activity. We then show that the antimicrobial activity of illuminated TAPP is additive with chloramphenicol and tobramycin for S. aureus and Escherichia coli, and synergistic for MRSA and Staphylococcus epidermidis. Chloramphenicol+methylene blue, another photosensitizer, also show additivity against S. aureus. In contrast, ceftriaxone and vancomycin do not strongly augment the low level effects of TAPP against S. aureus. Eukaryotic cells exhibit a dose-dependent toxicity with illuminated TAPP. Our results suggest that even sub-minimum inhibitory concentrations of photo-activated TAPP could be used to boost the activity of waning antibiotics. This may play an important role in treatments reliant on antibiotic controlled release systems where augmentation with photo-active agents could extend their efficacy.

L-carnitine exposure and mitochondrial function in human neuronal cells

L-Carnitine is a naturally occurring substance required in mammalian energy metabolism that functions by facilitating long-chain fatty acid entry into cellular mitochondria, thereby delivering substrate for oxidation and subsequent energy production. It has been purposed that L-carnitine may improve and preserve cognitive performance, and may lead to better cognitive aging through the life span, and several controlled human clinical trials with L-carnitine support the hypothesis that this substance has the ability to improve cognitive function. We further hypothesized that, since L-carnitine is an important co-factor of mammalian mitochondrial energy metabolism, acute administration of L-carnitine to human tissue culture cells should result in detectable increases in mitochondrial function. Cultures of SH-SY-5Y human neuroblastoma and 1321N1 human astrocytoma cells grown in 96-well cell culture plates were acutely administered L-carnitine hydrochloride, and then, mitochondrial function was assayed using the colorimetric 2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide inner salt cell assay kit in a VERSAmax tunable microplate reader. Significant increases in mitochondrial function were observed when human neuroblastoma or human astrocytoma cells were exposed to 100 nM (20 μg L-carnitine hydrochloride/L) to 100 μM (20 mg L-carnitine hydrochloride/L) concentrations of L-carnitine hydrochloride in comparison to unexposed cells, whereas no significant positive effects were observed at lower or higher concentrations of L-carnitine hydrochloride. The results of the present study provide insights for how L-carnitine therapy may significantly improve human neuronal function, but we recommend that future studies further explore different derivatives of L-carnitine compounds in different in vitro cell-based systems using different markers of mitochondrial function.

N-acetyl-cysteine prevents toxic oxidative effects induced by IFN-α in human neurons

Currently IFN-α is widely used for effective treatment of viral infections and several malignancies. However, IFN-α can cause neuropsychiatric disturbances and mental impairments, including fatigue, insomnia, depression, irritability and cognitive deficits. Molecular and cellular mechanisms leading to such side-effects are still poorly understood. Neurons seem to be an important target in mediating cellular effects induced by exposure to this cytokine, but so far little is known about IFN-α-induced effects on these cells. We have investigated the ability of IFN-α (2-100 ng/ml) to induce damage and toxicity to the human neuroblastoma SH-SY5Y cell line, commonly used for studying such phenomena, and the mechanisms underlying these effects. After 24 h treatment, IFN-α increased mitochondrial activity, whereas cell density was reduced in a dose- and time-dependent manner. This effect did not depend on reduced cell proliferation, but rather the activation of apoptosis, as revealed by an increased Bax:Bcl-2 mRNA ratio after 72-h IFN-α exposure. At this time-point, IFN-α also reduced the expression of the brain-derived neurotrophic factor gene, and induced an increase in reactive oxygen species (ROS). A co-treatment with N-acetyl-cysteine (NAC; 5 mm), a potent antioxidant and mitochondrial modulator, was able to counteract all of these IFN-α-induced effects. These findings demonstrated that IFN-α induces neurotoxicity and apoptosis that is, in part, very likely due to mitochondrial damages and production of ROS. We suggest that NAC, already tested for the treatment of psychiatric disorders, may be useful to prevent IFN-α-induced central side-effects in a safe and effective way.

Quercetin prevents protein nitration and glycolytic block of proliferation in hydrogen peroxide insulted cultured neuronal precursor cells (NPCs): Implications on CNS regeneration

Survival along with optimal proliferation of neuronal precursors determines the outcomes of the endogenous cellular repair in CNS. Cellular-oxidation based cell death has been described in several neurodegenerative disorders. Therefore, this study was aimed at the identification of the potent targets of oxidative damage to the neuronal precursors and its effective prevention by a natural flavonoid, Quercetin. Neuronal precursor cells (NPCs), Nestin+ and GFAP (Glial fibrillary acidic protein)+ were isolated and cultured from adult rat SVZ (subventricular zone). These cells were challenged with a single dose of H2O2 (50μM) and/or pre-treated with different concentrations of Quercetin. H2O2 severely limited the cellular viability and expansion of the neurospheres. Cellular-oxidation studies revealed reduction in glutathione dependent redox buffering along with depletion of enzymatic cellular antioxidants that might potentiate the nitrite (NO2(-)) and superoxide anion (O2(-)) mediated peroxynitrite (ONOO(-)) formation and irreversible protein nitration. We identified depleted PK-M2 (M2 isoform of pyruvate kinase) activity and apoptosis of NPCs revealed by the genomic DNA fragmentation and elevated PARP (poly ADP ribose polymerase) activity along with increased Caspase activity initiated by severely depolarised mitochondrial membranes. However, the pre-treatment of Quercetin in a dose-response manner prevented these changes and restored the expansion of neurospheres preferably by neutralizing the oxidative conditions and thereby reducing peroxynitrite formation, protein nitration and PK-M2 depletion. Our results unravel the potential interactions of oxidative environment and respiration in the survival and activation of precursors and offer a promise shown by a natural flavonoid in the protective strategy for neuronal precursors of adult brain.

Erythropoietin: new directions for the nervous system

New treatment strategies with erythropoietin (EPO) offer exciting opportunities to prevent the onset and progression of neurodegenerative disorders that currently lack effective therapy and can progress to devastating disability in patients. EPO and its receptor are present in multiple systems of the body and can impact disease progression in the nervous, vascular, and immune systems that ultimately affect disorders such as Alzheimer's disease, Parkinson's disease, retinal injury, stroke, and demyelinating disease. EPO relies upon wingless signaling with Wnt1 and an intimate relationship with the pathways of phosphoinositide 3-kinase (PI 3-K), protein kinase B (Akt), and mammalian target of rapamycin (mTOR). Modulation of these pathways by EPO can govern the apoptotic cascade to control β-catenin, glycogen synthase kinase-3β, mitochondrial permeability, cytochrome c release, and caspase activation. Yet, EPO and each of these downstream pathways require precise biological modulation to avert complications associated with the vascular system, tumorigenesis, and progression of nervous system disorders. Further understanding of the intimate and complex relationship of EPO and the signaling pathways of Wnt, PI 3-K, Akt, and mTOR are critical for the effective clinical translation of these cell pathways into robust treatments for neurodegenerative disorders.

Redox characterization of usnic acid and its cytotoxic effect on human neuron-like cells (SH-SY5Y)

Usnic acid (UA) is the most common and abundant lichenic secondary metabolite with potential therapeutic application. Anti-inflammatory and antitumour properties have already been reported and UA-enriched extracts are widely used to treat several diseases in the folk medicine. First, we performed in silico evaluation of UA interactions with genes/proteins and important compounds for cellular redox balance and NO pathway. Then, we assessed UA redox properties against different reactive species (RS) generated in vitro, and evaluated its action on SH-SY5Y neuronal like cells upon hydrogen peroxide (H(2)O(2)), since no in vitro neurotoxicological data has been reported so far. Total reactive antioxidant potential index (TRAP) showed a significant antioxidant capacity of UA at the highest tested concentration; UA was also effective against hydroxyl radicals and reduced the formation of nitric oxide. In vitro, lipoperoxidation was enhanced by UA and changed the cellular viability at highest concentration of 20μg/mL for 1 and 4h, as well as 2 and 20μg/mL for 24h of treatment, according to MTT reduction assay. Moreover, UA did not display protective effects against H(2)O(2)-induced cell death in any case. Evaluation of intracellular RS production by the DCFH-based assay indicated that UA was able to induce changes in basal RS production at concentration of 20μg/mL for 1h and from 2ng/mL to 20μg/mL for 4 and 24h. In conclusion, UA could display variable redox-active properties, according to different system conditions and/or cellular environment. Moreover, our results suggest that potential neurotoxicological effects of UA should be further studied by additional approaches; for instance, in vivo and clinical studies.