A novel action of palmitoyl-L-carnitine in human vascular endothelial cells

L-Palmitoylcarnitine potentiates plasmin and tPA to inhibit thrombosis

L-Palmitoylcarnitine (L-PC) is an important endogenous fatty acid metabolite. Its classical biological functions are involved in the regulations of membrane molecular dynamics and the β-oxidation of fatty acids. Decreased plasma long-chain acylcarnitines showed the association of venous thrombosis, implying anticoagulant activity of the metabolites and inspiring us to investigate if and how L-PC, a long-chain acylcarnitine, takes part in coagulation. Here we show that L-PC exerted anti-coagulant effects by potentiating the enzymatic activities of plasmin and tissue plasminogen activator (tPA). L-PC directly interacts with plasmin and tPA with an equilibrium dissociation constant (KD) of 6.47 × 10-9 and 4.46 × 10-9 M, respectively, showing high affinities. In mouse model, L-PC administration significantly inhibited FeCl3-induced arterial thrombosis. It also mitigated intracerebral thrombosis and inflammation in a transient middle cerebral artery occlusion (tMCAO) mouse model. L-PC induced little bleeding complications. The results show that L-PC has anti-thrombotic function by potentiating plasmin and tPA.

Oral Pathobiont-Induced Changes in Gut Microbiota Aggravate the Pathology of Nonalcoholic Fatty Liver Disease in Mice

Background & Aims

Periodontitis increases the risk of nonalcoholic fatty liver disease (NAFLD); however, the underlying mechanisms are unclear. Here, we show that gut dysbiosis induced by oral administration of Porphyromonas gingivalis, a representative periodontopathic bacterium, is involved in the aggravation of NAFLD pathology.

Methods

C57BL/6N mice were administered either vehicle, P. gingivalis, or Prevotella intermedia, another periodontopathic bacterium with weaker periodontal pathogenicity, followed by feeding on a choline-deficient, l-amino acid-defined, high-fat diet with 60 kcal% fat and 0.1% methionine (CDAHFD60). The gut microbial communities were analyzed by pyrosequencing the 16S ribosomal RNA genes. Metagenomic analysis was used to determine the relative abundance of the Kyoto Encyclopedia of Genes and Genomes pathways encoded in the gut microbiota. Serum metabolites were analyzed using nuclear magnetic resonance-based metabolomics coupled with multivariate statistical analyses. Hepatic gene expression profiles were analyzed via DNA microarray and quantitative polymerase chain reaction.

Results

CDAHFD60 feeding induced hepatic steatosis, and in combination with bacterial administration, it further aggravated NAFLD pathology, thereby increasing fibrosis. Gene expression analysis of liver samples revealed that genes involved in NAFLD pathology were perturbed, and the two bacteria induced distinct expression profiles. This might be due to quantitative and qualitative differences in the influx of bacterial products in the gut because the serum endotoxin levels, compositions of the gut microbiota, and serum metabolite profiles induced by the ingested P. intermedia and P. gingivalis were different.

Conclusions

Swallowed periodontopathic bacteria aggravate NAFLD pathology, likely due to dysregulation of gene expression by inducing gut dysbiosis and subsequent influx of gut bacteria and/or bacterial products.

Physiology of L-carnitine in plants in light of the knowledge in animals and microorganisms

L-carnitine is present in all living kingdoms where it acts in diverse physiological processes. It is involved in lipid metabolism in animals and yeasts, notably as an essential cofactor of fatty acid intracellular trafficking. Its physiological significance is poorly understood in plants, but L-carnitine may be linked to fatty acid metabolism among other roles. Indeed, carnitine transferases activities and acylcarnitines are measured in plant tissues. Current knowledge of fatty acid trafficking in plants rules out acylcarnitines as intermediates of the peroxisomal and mitochondrial fatty acid metabolism, unlike in animals and yeasts. Instead, acylcarnitines could be involved in plastidial exportation of de novo fatty acid, or importation of fatty acids into the ER, for synthesis of specific glycerolipids. L-carnitine also contributes to cellular maintenance though antioxidant and osmolyte properties in animals and microbes. Recent data indicate similar features in plants, together with modulation of signaling pathways. The biosynthesis of L-carnitine in the plant cell shares similar precursors as in the animal and yeast cells. The elucidation of the biosynthesis pathway of L-carnitine, and the identification of the enzymes involved, is today essential to progress further in the comprehension of its biological significance in plants.

Accumulation of Palmitoylcarnitine and Its Effect on Pro-Inflammatory Pathways and Calcium Influx in Prostate Cancer

BACKGROUND

Acylcarnitines are intermediates of fatty acid oxidation and accumulate as a consequence of the metabolic dysfunction resulting from the insufficient integration between β-oxidation and the tricarboxylic acid (TCA) cycle. The aim of this study was to investigate whether acylcarnitines accumulate in prostate cancer tissue, and whether their biological actions could be similar to those of dihydrotestosterone (DHT), a structurally related compound associated with cancer development.

METHODS

Levels of palmitoylcarnitine (palcar), a C16:00 acylcarnitine, were measured in prostate tissue using LC-MS/MS. The effect of palcar on inflammatory cytokines and calcium (Ca(2+) ) influx was investigated in in vitro models of prostate cancer.

RESULTS

We observed a significantly higher level of palcar in prostate cancerous tissue compared to benign tissue. High levels of palcar have been associated with increased gene expression and secretion of the pro-inflammatory cytokine IL-6 in cancerous PC3 cells, compared to normal PNT1A cells. Furthermore, we found that high levels of palcar induced a rapid Ca(2+) influx in PC3 cells, but not in DU145, BPH-1, or PNT1A cells. This pattern of Ca(2+) influx was also observed in response to DHT. Through the use of whole genome arrays we demonstrated that PNT1A cells exposed to palcar or DHT have a similar biological response.

CONCLUSIONS

This study suggests that palcar might act as a potential mediator for prostate cancer progression through its effect on (i) pro-inflammatory pathways, (ii) Ca(2+) influx, and (iii) DHT-like effects. Further studies need to be undertaken to explore whether this class of compounds has different biological functions at physiological and pathological levels. Prostate 76:1326-1337, 2016. © 2016 The Authors. The Prostate published by Wiley Periodicals, Inc.

Palmitoylcarnitine regulates estrification of lipids and promotes palmitoylation of GAP-43

Palmitoylcarnitine was previously shown to promote differentiation of neuroblastoma NB-2a cells. It was also observed to increase palmitoylation of several proteins and to diminish incorporation of palmitic acid to phospholipids, as well as to affect growth associated protein GAP-43 by decreasing its phosphorylation and interaction with protein kinase C. The present study was focused on influence of palmitoylcarnitine on palmitoylation of GAP-43 and lipid metabolism. Althought palmitoylcarnitine did not significantly affect the total phospholipids and fatty acid content, it increased incorporation of palmitate moiety to triacylglicerides and cholesterol esters, with a decrease of free cholesterol content. The presence of palmitoylcarnitine significantly increased the amount of covalently bound palmitate to GAP-43, which can regulate the signal transduction pathways.

Propionyl-L-carnitine improves hemodynamics and metabolic markers of cardiac perfusion during coronary surgery in diabetic patients

Diabetic hearts are particularly vulnerable to ischemia-reperfusion injury during cardiac surgery. Application of carnitine derivatives could be beneficial not only because of metabolic effects but also by protecting vasculature. This study aimed to evaluate hemodynamic changes associated with propionyl-L-carnitine and L-carnitine administration and its correlation with biochemical markers of cardiac vascular function.

METHODS

Sixty-eight diabetic patients undergoing cardiopulmonary bypass coronary operation were given intravenously 20 mg/kg b.w. L-carnitine (LC), 24 mg/kg b.w. propionyl-L-carnitine (PC), or placebo (Cont). Endothelin and nucleotide metabolites were determined intraoperatively in arterial and coronary sinus blood and heart biopsies.

RESULTS

Cardiac index at 6 and 12 h after cardiopulmonary bypass was significantly higher in PC (3.30 +/- 0.12 and 3.47 +/- 0.15 L/min/m2) as compared to Cont (2.92 +/- 0.13 and 2.91 +/- 0.16 L/min/m2; P = 0.04 and P = 0.01, respectively). Mean pulmonary artery pressure was lower in PC at 6 (20.8 +/- 0.91 mmHg) and 12 h (20.7 +/- 0.81 mmHg) in comparison to Cont (23.5 +/- 0.75 and 23.4 +/- 0.75 mmHg; P = 0.03 and P = 0.02, respectively). Trans-cardiac endothelin difference on reperfusion was higher in Cont (0.33 +/- 0.26 pmol/L) than in LC (-0.61 +/- 0.24 pmol/L, P = 0.012) and tended to be higher than in PC (-0.29 +/- 0.17 pmol/L, P = 0.056). Trans-cardiac hypoxanthine difference after 10 min reperfusion was significantly higher in Cont (6.22 +/- 1.08 micromol/L) in comparison to LC (3.17 +/- 0.66 micromol/L, P = 0.025) and PC (2.36 +/- 0.73 micromol/L, P = 0.006). Myocardial hypoxanthine concentration was lowest in PC.

CONCLUSIONS

Significant improvement of hemodynamics following propionyl-L-carnitine administration in diabetic patients undergoing on-bypass coronary surgery was accompanied by reduced trans-cardiac endothelin difference and rapid hypoxanthine washout during reperfusion suggesting improvement of metabolism or vascular function.

Dual Synergistic Effect: The Effect of Dexamethasone Plus Carnitine on Skin Flap Survival

Dexamethasone has well-known useful effects in dealing with the progression of necrosis. Carnitine is an endogenous cofactor, for having a regulatory action on the energy flow from different oxidative sources. The aim of this study was to determine whether combined local dexamethasone and systemic carnitine administration would result in an additive enhancement of skin flap survival in the rat model. A rectangular (3 cm x 11 cm) dorsal random skin flap was elevated on the rats and then sutured back into its original site with separate sutures. Overall, 40 rats were allocated randomly into 4 groups: Group 1 (control group, n = 10), group 2 (Dexamethasone group, n = 10, 2.5 mg/kg), group 3 (carnitine group, n = 10, 100 mg/kg), group 4 (dexamethasone plus carnitine group, n = 10).The mean flap survival area was 57.50 +/- 5.2% (mean survival area +/- SD) in control group (group 1), 71.5 +/- 4.8% in the dexamethasone group (group 2), 73.0 +/- 5.5% in the carnitine group (group 3), 85.30 +/- 6.1% in the dexamethasone plus carnitine group (group 4). In conclusion, based on the findings of this experimental study, the synergistic effect of carnitine and dexamethasone on skin flap viability is determined.

KB-R7943 reveals possible involvement of Na+-Ca2+ exchanger in elevation of intracellular Ca2+ in rat carotid arterial myocytes

A Na(+)/Ca(2+) exchanger (NCX) is one of the major regulators of intracellular Ca(2+) concentration ([Ca(2+)](i)) in cardiac muscle cells. Although vascular smooth muscle myocytes also express NCX proteins, their functional role has not been clear, mainly due to the lack of specific inhibitors of NCX and relatively low levels of expression of NCX. In the present study, we have examined the involvement of NCX in the Na(+) deficient (0 Na(+)) elevation of [Ca(2+)](i) in rat carotid arterial myocytes using KB-R7943, an inhibitor of NCX. Perfusion with a Na(+)-free bathing solution, prepared by replacement of Na(+) with N-methyl-D-glucamine, induced an elevation of [Ca(2+)](i), which was effectively inhibited by KB-R7943 (IC(50)=3.5 microM). This inhibition was reversed by washout of KB-R7943. In contrast, D600, a blocker of voltage dependent L-type Ca(2+) channels (VDCC), did not affect the 0 Na(+)-induced elevation of [Ca(2+)](i). Treatment of myocytes with ryanodine abolished the elevation of [Ca(2+)](i) caused by caffeine but not that caused by 0 Na(+). Application of Cd(2+), which is known to block NCX as well as VDCC, also significantly inhibited the 0 Na(+) induced elevation. These results suggest that KB-R7943 inhibits the extracellular Na(+) dependent ([Na(+)](o)) change in [Ca(2+)](i) in rat carotid arterial myocytes, which is presumably activated by the reverse mode of NCX.