Inflammation and carnitine in hemodialysis patients

Effect of L-Carnitine Supplementation on Inflammatory Markers and Serum Glucose in Hemodialysis Children: A Randomized, Placebo-Controlled Clinical Trial

OBJECTIVES

Chronic inflammation is present in a high proportion of the chronic kidney disease (CKD) population, which can increase the risk of cardiovascular disease. Moreover, it is known as the leading cause of death in these patients. In addition, change in glucose metabolism is another common problem among CKD population. In this regard, it was found that insulin resistance and inflammation can perpetuate each other and simultaneously cause atherosclerosis. Because some studies have previously shown the positive effects of L-carnitine on reducing inflammation and controlling blood sugar, in the present study, we examined the effects of L-carnitine supplementation on serum inflammatory markers, fasting blood sugar (FBS), free carnitine (FC), albumin levels, and quality of life score among children on hemodialysis.

METHOD

Twenty-four children on hemodialysis (aged between 6 and 18 years) were enrolled in this randomized clinical trial study. Thereafter, 12 patients received 50 mg/kg of L-carnitine and 12 patients received placebo for a 10-week period. Afterward, we determined serum FC, interleukin-6 (IL-6), high-sensitivity C-reactive protein, FBS, and albumin and Pediatrics Quality of Life scores once at the baseline and once after performing intervention for 10 weeks. Moreover, the one-way repeated measures analysis was used to evaluate the effects of L-carnitine supplementation.

RESULTS

Although oral L-carnitine supplementation led to the decreased high-sensitivity C-reactive protein, this change was not significant compared with the placebo. Also, L-carnitine supplementation has significantly reduced serum levels of IL-6 and FBS, which has also raised serum FC and Pediatrics Quality of Life scores compared with the placebo. Notably, no significant change was observed in serum albumin levels.

CONCLUSION

Given the significant reductions in IL-6 and FBS levels, L-carnitine supplementation appeared to have some positive effects on the inflammation, blood glucose control, and prevention of cardiovascular events in these patients, as well as the improvement of quality of life. In this regard, L-carnitine therapy with a longer duration is recommended to obtain more effective results.

Association of Low Serum l-Carnitine Levels with Peripheral Arterial Stiffness in Patients Who Undergo Kidney Transplantation

l-carnitine is an important co-factor in fatty-acid metabolism, and its deficiency is associated with insulin resistance, which is independently associated with arterial stiffness. This study evaluated the relationship between serum l-carnitine level and peripheral arterial stiffness (PAS) in kidney transplantation (KT). Fasting blood samples were collected from 65 patients who underwent KT. We measured the brachial–ankle pulse wave velocity, and 36 patients (55.4%) had PAS. Patients with PAS had a significantly higher percentage of diabetes (p = 0.001), hypertension (p = 0.033), and metabolic syndrome (p = 0.044); higher waist circumference (p = 0.010), systolic blood pressure (p = 0.002), serum triglyceride level (p = 0.040), insulin level (p = 0.002), and homeostasis model assessment of insulin resistance (p = 0.002); lower high-density lipoprotein cholesterol (p = 0.036) and serum l-carnitine levels (p < 0.001); older age (p = 0.041); and a longer KT duration (p = 0.025) than those without PAS. Statistical analysis revealed an independent association between PAS in KT and KT duration (95% confidence interval (CI): 1.003–1.054, p = 0.029) and serum l-carnitine levels (95% CI: 0.842–0.998, p = 0.044). The area under the receiver operating characteristic curve indicated that the diagnostic power of l-carnitine to predict PAS was 0.789 (95% CI: 0.670–0.881, p < 0.001). Serum-free l-carnitine level is negatively associated with PAS in patients who undergo KT.

Naturally Occurring Compounds: New Potential Weapons against Oxidative Stress in Chronic Kidney Disease

Oxidative stress is a well-described imbalance between the production of reactive oxygen species (ROS) and the antioxidant defense system of cells and tissues. The overproduction of free radicals damages all components of the cell (proteins, lipids, nucleic acids) and modifies their physiological functions. As widely described, this condition is a biochemical hallmark of chronic kidney disease (CKD) and may dramatically influence the progression of renal impairment and the onset/development of major systemic comorbidities including cardiovascular diseases. This state is exacerbated by exposure of the body to uremic toxins and dialysis, a treatment that, although necessary to ensure patients' survival, exposes cells to non-physiological contact with extracorporeal circuits and membranes with consequent mitochondrial and anti-redox cellular system alterations. Therefore, it is undeniable that counteracting oxidative stress machinery is a major pharmacological target in medicine/nephrology. As a consequence, in recent years several new naturally occurring compounds, administered alone or integrated with classical therapies and an appropriate lifestyle, have been proposed as therapeutic tools for CKD patients. In this paper, we reviewed the recent literature regarding the "pioneering" in vivo testing of these agents and their inclusion in small clinical trials performed in patients affected by CKD.

Protective Effects of L-Carnitine Against Delayed Graft Function in Kidney Transplant Recipients: A Pilot, Randomized, Double-Blinded, Placebo-Controlled Clinical Trial

OBJECTIVE

Delayed graft function (DGF) is an early complication after deceased donor kidney transplantation with significant adverse effects on graft outcomes. Ischemia-reperfusion injury during transplantation is a major cause of DGF. Tissue concentrations of carnitine, an antioxidant and regulator of cellular energy supply, decrease in the kidney following ischemia-reperfusion insult. Based on promising animal data, this study evaluated the possible protective effect of L-carnitine against DGF.

DESIGN

This study is a pilot, randomized, double-blind, placebo-controlled clinical trial that was conducted on kidney transplantation patients in kidney transplant ward of Imam Khomeini hospital complex affiliated to Tehran University of Medical Sciences, Tehran, Iran.

SUBJECTS

Patients older than 14 years old undergoing their first kidney transplantation from a deceased donor were evaluated for eligibility to take part in this study. Fifty-six patients were randomly assigned to L-carnitine or placebo groups.

INTERVENTION

During this trial, 3 g of oral L-carnitine or placebo was administered in 3 divided doses each day for 4 consecutive days starting the day before kidney transplantation (i.e., days -1, 0, 1, and 2).

MAIN OUTCOME MEASURE

The need for dialysis within the first week after transplantation, serum creatinine and urine output were assessed daily. After hospital discharge, patients were followed for 3 months regarding organ function.

RESULTS

DGF incidence did not differ between the L-carnitine and placebo groups (18.51% vs. 23.8%, respectively; P = .68). Total allograft failure within 3 months after kidney transplantation happened in 6 patients in the placebo and 1 patient in the L-carnitine group (P = .05).

CONCLUSION

This study showed no protective effects of oral L-carnitine supplementation against DGF occurrence recipients; however, 3-month graft loss was lower in the L-carnitine supplemented group.

Efficacy of L-carnitine supplementation on frailty status and its biomarkers, nutritional status, and physical and cognitive function among prefrail older adults: a double-blind, randomized, placebo-controlled clinical trial

Background

Frailty is a biological syndrome of decreased reserve and resistance to stressors due to decline in multiple physiological systems. Amino acid deficiency, including L-carnitine, has been proposed to be associated with its pathophysiology. Nevertheless, the efficacy of L-carnitine supplementation on frailty status has not been documented. Thus, this study aimed to determine the effect of 10-week L-carnitine supplement (1.5 g/day) on frailty status and its biomarkers and also physical function, cognition, and nutritional status among prefrail older adults in Klang Valley, Malaysia.

Methodology

This study is a randomized, double-blind, placebo-controlled clinical trial conducted among 50 prefrail subjects randomized into two groups (26 in L-carnitine group and 24 in placebo group). Outcome measures include frailty status using Fried criteria and Frailty Index accumulation of deficit, selected frailty biomarkers (interleukin-6, tumor necrosis factor-alpha, and insulin-like growth factor-1), physical function, cognitive function, nutritional status and biochemical profile.

Results

The results indicated that the mean scores of Frailty Index score and hand grip test were significantly improved in subjects supplemented with L-carnitine (P<0.05 for both parameters) as compared to no change in the placebo group. Based on Fried criteria, four subjects (three from the L-carnitine group and one from the control group) transited from prefrail status to robust after the intervention.

Conclusion

L-carnitine supplementation has a favorable effect on the functional status and fatigue in prefrail older adults.

Mitochondria: a new therapeutic target in chronic kidney disease

Cellular metabolic changes during chronic kidney disease (CKD) may induce higher production of oxygen radicals that play a significant role in the progression of renal damage and in the onset of important comorbidities. This condition seems to be in part related to dysfunctional mitochondria that cause an increased electron "leakage" from the respiratory chain during oxidative phosphorylation with a consequent generation of reactive oxygen species (ROS). ROS are highly active molecules that may oxidize proteins, lipids and nucleic acids with a consequent damage of cells and tissues. To mitigate this mitochondria-related functional impairment, a variety of agents (including endogenous and food derived antioxidants, natural plants extracts, mitochondria-targeted molecules) combined with conventional therapies could be employed. However, although the anti-oxidant properties of these substances are well known, their use in clinical practice has been only partially investigated. Additionally, for their correct utilization is extremely important to understand their effects, to identify the correct target of intervention and to minimize adverse effects. Therefore, in this manuscript, we reviewed the characteristics of the available mitochondria-targeted anti-oxidant compounds that could be employed routinely in our nephrology, internal medicine and renal transplant centers. Nevertheless, large clinical trials are needed to provide more definitive information about their use and to assess their overall efficacy or toxicity.

Investigation of inflammatory profile in MSUD patients: benefit of L-carnitine supplementation

Maple Syrup Urine Disease (MSUD) is a metabolic disorder caused by a severe deficiency of the branched-chain α-keto acid dehydrogenase complex activity which leads to the accumulation of branched-chain amino acids (BCAA) leucine (Leu), isoleucine and valine and their respective α-keto-acids in body fluids. The main symptomatology presented by MSUD patients includes ketoacidosis, failure to thrive, poor feeding, apnea, ataxia, seizures, coma, psychomotor delay and mental retardation, but, the neurological pathophysiologic mechanisms are poorly understood. The treatment consists of a low protein diet and a semi-synthetic formula restricted in BCAA and supplemented with essential amino acids. It was verified that MSUD patients present L-carnitine (L-car) deficiency and this compound has demonstrated an antioxidant and anti-inflammatory role in metabolic diseases. Since there are no studies in the literature reporting the inflammatory profile of MSUD patients and the L-car role on the inflammatory response in this disorder, the present study evaluates the effect of L-car supplementation on plasma inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), interferon-gamma (INF-ɣ), and a correlation with malondialdehyde (MDA), as a marker of oxidative damage, and with free L-car plasma levels in treated MSUD patients. Significant increases of IL-1β, IL-6, and INF-ɣ were observed before the treatment with L-car. Moreover, there is a negative correlation between all cytokines tested and L-car concentrations and a positive correlation among the MDA content and IL-1β and IL-6 values. Our data show that L-car supplementation can improve cellular defense against inflammation and oxidative stress in MSUD patients and may represent an additional therapeutic approach to the patients affected by this disease.

Effects of levocarnitine on brachial-ankle pulse wave velocity in hemodialysis patients: a randomized controlled trial

Background and Aims: Atherosclerotic cardiovascular disease is the most common cause of mortality in patients with end-stage kidney disease. Chronic kidney disease patients often exhibit a deficiency in l-carnitine due to loss during hemodialysis (HD). We studied the effects of l-carnitine supplementation on brachial-ankle pulse wave velocity (baPWV), a marker of atherosclerosis, in HD patients. Methods: This was a prospective, open-label, randomized, parallel controlled, multi-center trial testing the anti-atherosclerotic efficacy of oral l-carnitine administration (20 mg/kg/day). HD patients (n = 176, mean age, 67.2 ± 10.3 years old; mean duration of HD, 54 ± 51 months) with plasma free l-carnitine deficiency (<40 μmol/L) were randomly assigned to the oral l-carnitine group (n = 88) or control group (n = 88) and monitored during 12 months of treatment. Results: There were no significant differences in baseline clinical variables between the l-carnitine and control groups. l-carnitine supplementation for 12 months significantly increased total, free, and acyl carnitine levels, and reduced the acyl/free carnitine ratio. The baPWV value decreased from 2085 ± 478 cm/s at baseline to 1972 ± 440 cm/s after six months (p < 0.05) to 1933 ± 363 cm/s after 12 months (p < 0.001) of l-carnitine administration, while no significant changes in baPWV were observed in the control group. Baseline baPWV was the only factor significantly correlated with the decrease in baPWV. Conclusions: l-carnitine supplementation significantly reduced baPWV in HD patients. l-carnitine may be a novel therapeutic strategy for preventing the progression of atherosclerotic cardiovascular disease.

Urinary excretion of L-carnitine, acetyl-L-carnitine, propionyl-L-carnitine and their antioxidant activities after single dose administration of L-carnitine in healthy subjects

The urine excretion of L-carnitine (LC), acetyl-L-carnitine (ALC) and propionyl-Lcarnitine (PLC) and their relations with the antioxidant activities are presently unknown. Liquid L-carnitine (2.0 g) was administered orally as a single dose in 12 healthy subjects. Urine concentrations of LC, ALC and PLC were detected by HPLC. Superoxide dismutase (SOD), total antioxidative capacity (T-AOC), malondialdehyde (MDA) and nitrogen monoxidum (NO) activities were measured by spectrophotometric methods. The 0~2 h, 2~4 h, 4~8 h, 8~12 h, 12~24 h excretion of LC was 53.13±31.36 µmol, 166.93±76.87 µmol, 219.92±76.30 µmol, 100.48±23.89 µmol, 72.07±25.77 µmol, respectively. The excretion of ALC was 29.70±14.43 µmol, 80.59±32.70 µmol, 109.85±49.21 µmol, 58.65±18.55 µmol, and 80.43±35.44 µmol, respectively. The urine concentration of PLC was 6.63±4.50 µmol, 15.33±12.59 µmol, 15.46±6.26 µmol, 13.41±11.66 µmol and 9.67±7.92 µmol, respectively. The accumulated excretion rate of LC was 6.1% within 24h after its administration. There was also an increase in urine concentrations of SOD and T-AOC, and a decrease in NO and MDA. A positive correlation was found between urine concentrations of LC and SOD (r = 0.8277) or T-AOC (r = 0.9547), and a negative correlation was found between urine LC excretions and NO (r = -0.8575) or MDA (r = 0.7085). In conclusion, a single oral LC administration let to a gradual increase in urine L-carnitine excretion which was associated with an increase in urine antioxidant enzymes and the total antioxidant capacities. These data may be useful in designing therapeutic regimens of LC or its analogues in the future.

Prevalence of protein-energy wasting and its various types in Iranian hemodialysis patients: a new classification

BACKGROUND

This study was designed to determine the prevalence of protein-energy wasting (PEW) and its various types in hemodialysis (HD) patients in Tehran, Iran.

METHODS

For this cross-sectional study, 291 HD patients were randomly selected. The nutritional status of the patients was determined by subjective global assessment (SGA) and their dietary intakes were assessed using a 4-day dietary recall. In addition, serum high-sensitive C-reactive protein (hs-CRP) was measured.

RESULTS

The prevalence of mild-to-moderate and severe PEW based on SGA was 60.5% and 1% in Tehran HD patients, respectively. The prevalence of various types of PEW in HD patients was 20.5% type I (inadequate energy or protein intake without inflammation), 65.5% type IIa (inadequate energy or protein intake with inflammation), and 14% type IIb (adequate energy and protein intake with inflammation). Of the total HD patients with no PEW based on SGA, about 3.5% had type 0 normal nutritional status (adequate energy and protein intake without inflammation), 34% had type I normal nutritional status (inadequate energy or protein intake without inflammation), 55.5% had type IIa normal nutritional status (inadequate energy or protein intake with inflammation), and 7% had type IIb normal nutritional status (adequate energy and protein intake with inflammation).

CONCLUSION

PEW in Tehran HD patients is considerably prevalent and PEW type IIa is the most common type. In addition, HD patients with no PEW based on SGA should also be paid attention because they may be in the early stages of inadequate intake of energy and/or protein and inflammation.

Mechanistic contribution of carnitine deficiency to geriatric frailty

Frailty is a geriatric syndrome characterized by muscle weakness, sarcopenia, and fatigue, and is associated with several adverse health outcomes, including disability. Design of therapeutic interventions for geriatric frailty has been challenging and may be because of inadequate understanding of its biological underpinnings. Carnitine is important for energy production in skeletal muscles and there seems to be a negative correlation between advancing age and muscle carnitine levels. Carnitine deficiency may therefore contribute to geriatric frailty. Age-associated carnitine deficiency from a variety of etiologies, including organic cation transporter (OCTN2) mutation and carnitine palmitoyltransferase II (CPT) deficiency, may potentially explain the relationship between carnitine-associated mitochondrial dysfunction and geriatric frailty. Development of therapeutic agents capable of prevention or reversal of carnitine deficiency in older adults may minimize the occurrence of frailty in geriatric populations.

Surface-induced cell signaling events control actin rearrangements and motility

Understanding the interrelationship between material surface properties and the biological response to such materials remains a fundamental scientific challenge, as well as being of considerable practical importance in medicine. Through the use of a homologous series of copolymers of increasing hydrophobicity, we aimed to illuminate the interplay between material surface hydrophobicity and signalling events within cells in contact with this model system. Extending previous work, we hereby unravel key pathways controlling cell motility and the formation of a stellate phenotype, following interaction with polymer-coated surfaces. We reveal a comparative increase in cellular motility with increasing surface hydrophilicity, conjoint with an arrest in cell cycle progression. We also show an anomalous turnover of actin within the cell as a function of changing surface hydrophobicity. Finally, we show that cyclic adenosine monophosphate may be an effector of the cellular phenotype, as its production is increased in response to changes in the surface properties. These results highlight important signaling events which control actin rearrangements and the subsequent motility and its effectors.

The role of inflammatory markers in the cardioprotective effect of L-carnitine in L-NAME-induced hypertension

BACKGROUND

The mechanism(s) underlying the effects of L-carnitine (beta-hydroxy-gamma-N-trimethylammonium-butyrate; LC) in cardiovascular diseases are not well clarified. Previous studies have demonstrated that oxidative stress and inflammation contribute to arterial hypertension, and antioxidant and/or anti-inflammatory therapies have been proposed. We hypothesized that LC might attenuate the hypertensive status through an inhibition of inflammation process.

METHODS

Heart mRNA expression and plasma levels of inflammatory markers, interleukin-1 beta (IL-1 beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha), were measured in rats that were made hypertensive with N(omega)-nitro-L-arginine methyl ester (L-NAME) and subjected to a simultaneous administration of LC. To clarify the role of the renin-angiotensin system (RAS) in this effect of LC, the activity and expression of angiotensin I-converting enzyme (ACE) as well as the expression of angiotensin II type I receptor (AT1R) in the heart were also determined.

RESULTS

LC produced a significant, but not complete, reduction of blood pressure in L-NAME-treated rats. Plasma levels and heart expression of IL-1 beta, IL-6, and TNF-alpha showed an increase in the L-NAME group, which was reversed by LC treatment. The plasma ACE activity was not modified between normotensive and hypertensive rats although LC treatment produced a reduction of these values in the latter. Finally, protein and mRNA expression of ACE and AT1R was enhanced in the heart of L-NAME-treated animals, and LC reversed these values.

CONCLUSIONS

The chronic administration of LC reduces blood pressure and attenuates the inflammatory process associated with arterial hypertension. LC might produce a partial inactivation in the RAS resulting in a reduction in the production and effects of angiotensin II.

The human peripheral blood mononuclear cell proteome responds to a dietary flaxseed-intervention and proteins identified suggest a protective effect in atherosclerosis

Flaxseed is one of the richest sources of lignans that are converted to enterolactone by the intestinal microflora. Enterolactone has been suggested to be the prime active compound mediating atherosclerosis-protective effects that were shown for flaxseed. The effects of a 1-wk intervention with 0.4 g of flaxseed/kg body weight per day on enterolactone plasma levels in seven healthy men revealed that all participants (PAs) responded with enhanced enterolactone plasma levels. Proteome analysis of peripheral blood mononuclear cells (PBMC) from donors before, during, and after the intervention showed that flaxseed consumption affected significantly the steady-state levels of 16 proteins of which four were altered in a similar manner when blood mononuclear cells were exposed ex vivo to enterolactone. Enhanced levels of peroxiredoxin and reduced levels of the long-chain fatty acid beta-oxidation multienzyme complex may be taken as indicators of a reduced oxidative stress whereas reduced levels of glycoprotein IIIa/II could indicate improved protection from thrombotic and inflammatory processes. In conclusion, the blood mononuclear cell proteome responds to dietary flaxseed intake with changes in a number of atherosclerosis-relevant proteins that may be taken as biomarkers of exposure and some of these changes observed can be attributed to the action of the lignan metabolite enterolactone.

L-Carnitine ameliorates methotrexate-induced oxidative organ injury and inhibits leukocyte death

Methotrexate (MTX), a folic acid antagonist widely used for the treatment of a variety of tumors and inflammatory diseases, affects normal tissues that have a high rate of proliferation, including the hematopoietic cells of the bone marrow and the gastrointestinal mucosal cells. To elucidate the role of free radicals and leukocytes in MTX-induced oxidative organ damage and the putative protective effect of L-carnitine (L-Car), Wistar albino rats were administered a single dose of MTX (20 mg/kg) followed by either saline or L-Car (500 mg/kg) for 5 days. After decapitation of the rats, trunk blood was obtained, and the ileum, liver, and kidney were removed for histological examination and for the measurement of malondialdehyde (MDA) and glutathione (GSH) levels, myeloperoxidase (MPO) activity, and collagen content. Our results showed that MTX administration increased the MDA and MPO activities and collagen content and decreased GSH levels in all tissues, while these alterations were reversed in L-Car-treated group. The elevated serum TNF-alpha level observed following MTX treatment was depressed with L-Car. The oxidative burst of neutrophils stimulated by Annexin V was reduced in the saline-treated MTX group, while L-Car abolished this inhibition. Similarly, flow cytometric measurements revealed that leukocyte apoptosis was increased in MTX-treated animals, while L-Car reversed these effects. Severe degeneration of the intestinal mucosa, liver parenchyma, and glomerular and tubular epithelium observed in the saline-treated MTX group was improved by L-Car treatment. These results suggest that L-Car, possibly via its free radical scavenging and antioxidant properties, ameliorates MTX-induced oxidative organ injury and inhibits leukocyte apoptosis. Thus, supplementation with L-Carnitine as an adjuvant therapy may be promising in alleviating the systemic side-effects of chemotherapeutics.

Advances in Carnitine in Chronic Uremia

Carnitine is a conditionally essential metabolite that plays a critical role in cell physiology. Carnitine is necessary for fatty acid transport to sites of beta-oxidation in the mitochondria, where it helps to prevent organic acid accumulation. Because of these key regulatory functions, carnitine represents a crucial determinant of mitochondrial energy metabolism, whose deficiency may lead to metabolic and clinical disturbances. Loss of carnitine through dialytic membranes occurs in maintenance hemodialysis, resulting in potential carnitine depletion and relative increments of esterified carnitine forms. Carnitine supplementation has been shown to counteract such alterations and may be associated with clinical benefit. In particular, carnitine supplementation in patients on hemodialysis may enhance response to erythropoietin, resulting in improved hematologic status. Carnitine was also reported to improve exercise tolerance and intradialytic symptoms. Carnitine supplementation may enhance insulin resistance, inflammatory and antioxidant status, protein balance, lipid profile, and cardiac function. Carnitine administration can be useful for selected patients on dialysis who do not adequately respond to standard therapy.