High dose L-carnitine improves immunologic and metabolic parameters in AIDS patients

Human immunodeficiency virus and antiretroviral therapy-mediated immune cell metabolic dysregulation in children born to HIV-infected women: potential clinical implications

Commencing lifelong antiretroviral therapy (ART) immediately following HIV diagnosis (Option B+) has dramatically improved the health of HIV-infected women and their children, with the majority being of HIV-exposed children born uninfected (HEU). This success has led to an increasing population of HIV-infected women receiving ART during pregnancy and children exposed to ART in utero. Nonetheless, a small proportion of children are still infected with HIV (HEI) each year. HEI children suffer from reduced immunocompetence and host-defence, due to CD4+ T lymphocyte depletion, but also dysregulation of other immune cells including CD8+ T lymphocytes, natural killer (NK) cells, macrophages including B lymphocytes. Furthermore, although HEU children are uninfected, altered immune responses are observed and associated with increased vulnerability to infections. The mechanisms underlying immune dysregulation in HEU children remain poorly described. Building on early studies, emerging data suggests that HIV/ART exposure early in life affects cell metabolic function of HEU children. Prenatal HIV/ART exposure has been associated with dysregulation of mitochondria, including impaired DNA polymerase activity. Furthermore, dysregulation of oxidative phosphorylation (OXPHOS) causes a decreased generation of adenosine triphosphate (ATP) and increased production of reactive oxygen species (ROS), resulting in oxidative stress. These altered metabolic processes can affect immune cell viability and immune responses. Recent studies have indicated that immune-metabolic dysregulation may contribute to HIV-associated pathogenesis and clinical observations associated with HIV and ART exposure in HEU/HEI children. Given the critical role metabolic processes in immune cell functioning, immune-metabolic dysregulation in HEU and HEI children may have implications in effective host-defence responses against pathogens, as well as efficacy of standard ART regimens and future novel HIV cure approaches in HEI children. At the same time, targeting metabolic pathways of immune cells may provide safer and novel approaches for HIV cure strategies. Here, we review the current literature investigating immune-metabolic dysregulation in paediatric HIV pathogenesis.

Clinical Effects of L-Carnitine Supplementation on Physical Performance in Healthy Subjects, the Key to Success in Rehabilitation: A Systematic Review and Meta-Analysis from the Rehabilitation Point of View

L-carnitine supplementation improves body strength, sports endurance and exercise capacity, as well as delaying the onset of fatigue. The aim of this study was to identify the correct dosage of supplementation to obtain improvements in physical performance and evaluate the changes related to L-carnitine supplementation in specific metabolic parameters, such as serum lactate, VO₂, serum total and free carnitine at rest and after physical activities, in healthy subjects. The search was conducted on PubMed, EMBASE, Cochrane Library, Scopus and Web of Science and identified 6404 articles with the keywords: "carnitine" AND "exercises" OR "rehabilitation" OR "physical functional performance" OR "physical activity" OR "sports" OR "health" OR "healthy". A total of 30 publications met the inclusion criteria and were included in the systematic review. The meta-analysis did not show any significant differences in serum lactate values at rest and after exercise in healthy subjects who took L-carnitine supplementation (p > 0.05). On the contrary, L-carnitine administration significantly changed maximal oxygen consumption (VO₂) at rest (p < 0.005), serum free and total carnitine at rest and after exercise (p < 0.001). The dosage of supplementation that obtained a significant change in serum total carnitine was 2 g/dL for 4 weeks at rest, 1 g/dL for 3 weeks after exercise, and in serum free carnitine was 2 g/dL for 3 weeks and 2 g/dL for 4 weeks at rest. Based on our study, serum total and free carnitine at rest and after exercise, and VO₂ at rest could be used to clinically follow individuals during physical activity and rehabilitation programs. Moreover, the supplementation should have a correct dosage to have maximum effect. Other robust trials are needed to find the best dosage to obtain positive results in metabolic parameters and in physical performance.

How Genetics Might Explain the Unusual Link Between Malaria and COVID-19

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-associated coronavirus disease 2019 (COVID-19) pandemic has been the subject of a large number of studies in recent times. Here, starting from the evidence that in Italy, the areas with the lowest number of COVID-19 cases were those with the highest incidence of malaria in the early 1900's, we explore possible inverse relationships between malaria and COVID-19. Indeed, some genetic variants, which have been demonstrated to give an advantage against malaria, can also play a role in the incidence and severity of SARS-CoV-2 infections (e.g., the ACE2 receptor). To verify this scientific hypothesis, we here use public data from whole-genome sequencing (WGS) experiments to extrapolate the genetic information of 46 world populations with matched COVID-19 data. In particular, we focus on 47 genes, including ACE2 and genes which have previously been reported to play a role in malaria. Only common variants (>5%) in at least 30% of the selected populations were considered, and, for this subset, we correlate the intra-population allele frequency with the COVID-19 data (cases/million inhabitants), eventually pinpointing meaningful variants in 6 genes. This study allows us to distinguish between positive and negative correlations, i.e., variants whose frequency significantly increases with increasing or decreasing COVID-19 cases. Finally, we discuss the possible molecular mechanisms associated with these variants and advance potential therapeutic options, which may help fight and/or prevent COVID-19.

Plasma L-Carnitine and L-Lysine Concentrations in HIV-Infected Patients

Background:

Virus infections are associated with significant alterations in host cells amino acids profiles that support biosynthetic demands necessary for production of viral progeny. Amino acids play an important role in the pathogenesis of all virus-related infections both as basic substrates for protein synthesis and as regulators in many metabolic pathways.

Objective:

Our aim was to determine the changes in plasma L-carnitine levels and its amino acid precursor (L-lysine) in HIV-infected patients.

Methods:

We performed a case-control study of 430 HIV-1 infected males (non-vegetarians) without any restriction in the nourishment, before highly active antiretroviral therapy (HAART) and 125 HIV-1 subjects after the introduction of HAART who were periodically monitored in the Municipal Center of HIV/AIDS prophylaxis, Surgut, Russian Federation

Results:

The plasma total (TC) and free (FC) L-carnitine concentrations markedly decreased with the clinical stages of HIV infection. The mean plasma TC, FC and L-lysine levels were significantly lower in asymptomatic stage (A) and advanced CDC stages (B, C) HIV-infected patients compared with our reference values. The total and free L-carnitine and its amino acid precursor concentrations mild increased in HIV-infected subjects after the introduction of HAART.

Our data revealed that L-lysine amino acid and its derivative (TC) levels were negatively correlated with viral load and inversely with CD4 count lymphocytes in the total cohort.

Conclusion:

The study results show that there was evidence for an association between plasma L-carnitine, L-lysine and HIV-1 RNA levels, immunological markers and clinical stages of HIV infection. The obtained data indicate that level changes of these host essential nutritional elements can play an important role in the HIV life cycle. These findings are important for understanding the pathophysiology of HIV infection and must be considered in further research for the development of new approaches in the treatment of the disease.

Carnitine in Human Immunodeficiency Virus Type 1 Infection/Acquired Immune Deficiency Syndrome

There is an increasing body of evidence that subgroups of patients infected with human immunodeficiency virus type 1 possess carnitine deficiency. Secondary carnitine deficiencies in these individuals may result from nutritional deficiencies, gastrointestinal disturbances, renal losses, or shifts in metabolic pathways. However, tissue depletion precipitated by drug toxicities, particularly zidovudine, is a major etiology and concern. Carnitine deficiency may impact on energy and lipid metabolism, causing mitochondrial and immune dysfunction. There are convincing laboratory data showing the in vitro ameliorative effects of L-carnitine supplementation on zidovudine-induced myopathies and lymphocyte function. Studies measuring the impact of L-carnitine supplementation on clinical characteristics are ongoing. (J Child Neurol 1995; 10(Suppl):2540-2544).

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.

Carnitine and septic shock: a review

Most studies have reported reduced carnitine levels in the tissues of patients with sepsis, probably due to increased urinary excretion. Because of the increased utilization of fatty acids and ketone bodies as sources of energy in sepsis, the carnitine deficiency can further impair the fuel metabolism and contribute to the unregulated lipid metabolism in these patients.

Recently, experimental and clinical studies have shown that carnitine and its congeners are able to: (a) downmodulate the spontaneous and endotoxin (LPS)-triggered overproduction of tumor necrosis factor (TNF)-alpha; (b) ameliorate the lipid metabolism; and (c) reduce the severity of illness, accelerate recovery, and, in some cases, improve survival in experimental septic shock.

Many questions concerning the ultimate molecular mechanism of action of these compounds in endotoxaemia are still unanswered. Yet, these compounds may be helpful in patients with sepsis, when associated with conventional therapy, in that they can effectively reduce TNF-alpha levels and ameliorate the host's metabolic processes.

Low levels of short- and medium-chain acylcarnitines in HIV-infected patients

BACKGROUND

Carnitine plays an essential role in fatty acid metabolism, exerts substantial antioxidant action and regulates immune functions. We hypothesized that a disturbed carnitine metabolism could be involved in progression of HIV infection.

MATERIALS AND METHODS

Plasma levels of L-carnitine, its precursors, and short-, medium- and long-chain acylcarnitines were analysed with HPLC/mass spectrometry in HIV-infected patients with various disease severities including patients who acquired Mycobacterium avium complex (MAC) infection. In vitro, we examined the MAC-purified protein derivate (PPD)-induced release of TNF-α and IFN-γ in peripheral blood mononuclear cells (PBMCs) from patients with either high or low plasma levels of acylcarnitines.

RESULTS

Plasma levels of the short-chain (e.g. propionyl-carnitine) and medium-chain (e.g. octanoyl-carnitine) acylcarnitines were reduced in patients with advanced HIV infection. These acylcarnitines gradually decreased in rapid progressors, while minimal changes were observed in the nonprogressors. Plasma levels of propionyl-carnitine and octanoyl-carnitine significantly increased during antiretroviral therapy (ART). However, ART did not restore levels to those observed in healthy controls. Depletion of propionyl-carnitine and octanoyl-carnitine was observed prior to MAC infection, and the release of TNF-α and IFN-γ from PBMC was decreased after stimulation with MAC-PPD in samples from HIV-infected patients with low levels of propionyl-carnitine or octanoyl-carnitine.

CONCLUSIONS

Our findings suggest an association between disturbed acylcarnitine metabolism, immune dysregulation and disease progression in HIV-infected patients. Low levels of propionyl-carnitine and octanoyl-carnitine were associated with increased susceptibility to MAC infection in HIV patients with advanced disease.

L-Carnitine Supplementation Reduces Short-Term Neutrophil-Lymphocyte Ratio in Patients Undergoing Coronary Artery Bypass Grafting

This study aims to investigate whether preoperative L-carnitine supplementation affects the neutrophil-to-lymphocyte ratio (NLR) in patients undergoing coronary artery bypass grafting surgery. The neutrophil-to-lymphocyte ratio is an inflammatory marker that has proven usefulness for predicting postoperative complications in coronary artery bypass surgery. A lot of studies concerning the role of L-carnitine in the immune system have been performed, contradictory results have been reported on its effects on absolute numbers of WBC subtypes. This randomized, double-blinded, placebo-controlled study was conducted among patients scheduled for coronary artery bypass grafting surgery between June 2012 and December 2013 in our cardiovascular surgery clinic. A total of 60 consecutive patients were randomized and divided into 2 groups. The first group received 2 g of L-carnitine in 1000 mL of 0.9% saline solution infused over 24 hours for each of the 3 preoperative days (L-carnitine group, n = 30), or only 1000 mL of 0.9% saline solution for the same time period (placebo group, n = 30). The basal values of leukocyte, neutrophil, lymphocyte counts, and neutrophil to lymphocyte ratio were similar in the 2 groups. After L-carnitine supplementation (just before surgery), leukocyte and neutrophil counts of the L-carnitine group were significantly lower than those of the placebo group (7.7 ± 1.5 versus 9.7 ± 2.6, P < 0.001 and 4.6 ± 1.3 versus 6.5 ± 2.2, P < 0.001). On postoperative day 1, lymphocyte counts were significantly higher in the L-carnitine group (1.1 ± 0.6 versus 0.8 ± 0.9, P < 0.001). Moreover, the increase in NLR was significantly lower in the L-carnitine group at postoperative day 1 (20.7 ± 13.8 versus 10.8 ± 4.1, P < 0.001). Preoperative L-carnitine supplementation may reduce neutrophil-lymphocyte ratio during the early postoperative period of coronary artery bypass grafting surgery.

Potential inhibitory effects of L-carnitine supplementation on tissue advanced glycation end products in patients with hemodialysis

BACKGROUND AND AIMS

Advanced glycation end products (AGEs) contribute to cardiovascular disease in patients with hemodialysis (HD). We have recently found that carnitine levels are inversely associated with skin AGE levels in HD patients. We examined whether L-carnitine supplementation reduced skin AGE levels in HD patients with carnitine deficiency.

METHODS

This was a single-center study. One hundred and two HD patients (total carnitine levels <50 μmol/L) were enrolled and randomized to either oral administration of L-carnitine (900 mg/day) (n=51) or control (n=51). After 6 months, metabolic and inflammatory variables, including serum levels of carnitine, were measured. Skin AGE levels were determined by evaluating skin auto-fluorescence with an AGE-reader.

RESULTS

There were no significant differences of clinical variables at baseline between the control and L-carnitine therapy group. Thirty-two patients did not complete the assessment or treatment of the study. Oral L-carnitine supplementation for 6 months significantly increased low-density lipoprotein cholesterol (LDL-C), triglycerides, total, free, and acyl carnitine levels, while it decreased alanine transaminase, acyl/free carnitine ratio, β₂-microglobulin, and skin AGE values. Change in total carnitine values from baseline (Δtotal carnitine) and Δfree carnitine were inversely associated with Δskin AGE levels in L-carnitine-treated patients (p=0.036 and p=0.016, respectively). In multiple regression analysis, Δfree carnitine was a sole independent determinant of Δskin AGEs (R²=0.178).

CONCLUSIONS

The present study demonstrated that oral L-carnitine supplementation significantly decreased skin AGE levels in HD patients with carnitine deficiency. These observations suggest that supplementation of L-carnitine might be a novel therapeutic strategy for preventing the accumulation of tissue AGEs in carnitine-deficient patients with HD.

In vitro assessment of antiretroviral drugs demonstrates potential for ototoxicity

Several studies have reported an increased incidence of auditory dysfunction among HIV/AIDS patients. We used auditory HEI-OC1 cells in cell viability, flow cytometry and caspases 3/7-activation studies to investigate the potential ototoxicity of fourteen HIV antiretroviral agents: Abacavir, AZT, Delavirdine, Didenosine, Efavirenz, Emtricitabine, Indinavir, Lamivudine, Nefinavir, Nevirapine, Tenofovir, Ritonavir, Stavudine and Zalcitabine, as well as combinations of these agents as used in the common anti-HIV cocktails Atripla™, Combivir™, Epzicom™, Trizivir™, and Truvada™. Our results suggested that most of the single assayed anti-HIV drugs are toxic for HEI-OC1 auditory cells. The cocktails, on the other hand, decreased auditory cells' viability with high significance, with the following severity gradient: Epzicom ∼ Trizivir >> Atripla ∼ Combivir > Truvada. Interestingly, our results suggest that Trizivir- and Epzicom-induced cell death would be mediated by a caspase-independent mechanism. l-Carnitine, a natural micronutrient known to protect HEI-OC1 cells against some ototoxic drugs as well as to decrease neuropathies associated with anti-HIV treatments, increased viability of cells treated with Lamivudine and Tenofovir as well as with the cocktail Atripla, but had only minor effects on cells treated with other drugs and drug combinations. Altogether, these results suggest that some frequently used anti-HIV agents could have deleterious effects on patients' hearing, and provide arguments in favor of additional studies aimed at elucidating the potential ototoxicity of current as well as future anti-HIV drugs.

Carnitine deficiency and its possible risk factors in TB patients: first report

AIM

To assess carnitine serum levels and possible risk factors of its deficiency in patients with TB.

PATIENTS & METHODS

All newly diagnosed TB patients admitted to an infectious diseases ward were recruited. Demographic, clinical and paraclinical characteristics of the patients were collected. Total carnitine serum concentrations were measured. To investigate factors that can predict carnitine deficiency, logistic regression analysis with odds ratio and 95% CI was performed.

RESULTS

The mean ± standard deviation of carnitine serum levels of patients was 43.77 ± 32.92 µmol/l. Carnitine deficiency was detected in 47.7% of the study population. According to the final model of multivariate logistic regression analysis, increased serum triglyceride levels and hypoalbuminemia were identified as predictive factors of carnitine deficiency in TB patients aged over 35 years old.

CONCLUSION

Nearly half of Iranian patients with TB were carnitine-deficient. Increased serum triglyceride levels and hypoalbuminemia were identified as independent risk factors of carnitine deficiency in patients aged over 35 years. Considering malnutrition as a major risk factor of TB and the safety of carnitine supplementation, use of carnitine as an adjunctive modality instead of other standard interventions may show beneficial effects in patients with TB.

Evaluation of serum level of carnitine in HIV-positive individuals and its possible explanatory factors

Aims: This cross-sectional study evaluated the status of serum carnitine level and its possible explanatory factors in Iranian HIV-positive patients. Materials & methods: During a 1-year period, 210 HIV-positive patients older than 18 years of age were enrolled in the study. Serum carnitine concentrations of the patients were measured using radioimmunoassay kits. Probable correlations between the patients’ demographic and clinical characteristics with their serum levels of carnitine were determined in this study. Results: In comparison with normal serum concentration of carnitine in a healthy population, 63.45% of the patients had carnitine deficiency. Receiving antiretroviral regimen, duration of HIV infection, receiving fibrate drugs, serum total cholesterol, fasting blood sugar and serum triglyceride had significant correlations with serum level of carnitine of the patients. Conclusion: The results of the present study showed that carnitine deficiency is prevalent in Iranian HIV/AIDS patients. Nutritional risk assessment of HIV-positive individuals at first visit and in the follow-up is essential.

Potential benefits of carnitine in HIV-positive patients

Carnitine is a nonessential amino acid that has a central role in lipid peroxidation and mitochondrial metabolism. Carnitine deficiency is rare in adult human subjects who have a normal diet and no underlying chronic diseases. Studies have shown that HIV-infected patients are at increased risk of carnitine deficiency due to decreased intake, increased metabolism, gastrointestinal problems, HIV infection itself, concomitant infections, underlying disease, concomitant drugs and antiretroviral therapy. Decreased serum and muscle carnitine content was reported following antiretroviral therapy in HIV-positive patients. The beneficial effects of carnitine on the human immune system, such as prevention of CD4 cell apoptosis, was reported in these patients. Additionally, polyneuropathy, myopathy, lactic acidosis, dyslipidemia and lipodystrophy are complications of antiretroviral therapy that have been proposed to potentially be related to carnitine deficiency and mitochondrial dysfunction. Carnitine may have a significant role in improving some aspects of mitochondrial toxicity induced by an antiretroviral regimen, such as lipodystrophy. Also, there are nearly sufficient data to support the beneficial effects of carnitine in improving the symptoms of lactic acidosis following antiretroviral therapy. According to available data, it is concluded that carnitine may have beneficial effects in the treatment of antiretroviral-induced neuropathy. Most of the evidence supports carnitine supplementation as a treatment strategy rather than prophylaxis for antiretroviralinduced complications. Several studies have shown the prevalence of carnitine deficiency and its role in different aspects of infection and antiretroviral-induced complications in HIV-positive patients, but the probable beneficial effects of carnitine supplementation are not clear in this population. In this review, we have collected and categorized available evidence regarding the potential benefits of carnitine supplementation in HIV-infected individuals.

Randomized phase III clinical trial of a combined treatment with carnitine + celecoxib ± megestrol acetate for patients with cancer-related anorexia/cachexia syndrome

BACKGROUND & AIMS

A phase III, randomized non-inferiority study was carried out to compare a two-drug combination (including nutraceuticals, i.e. antioxidants) with carnitine + celecoxib ± megestrol acetate for the treatment of cancer-related anorexia/cachexia syndrome (CACS): the primary endpoints were increase of lean body mass (LBM) and improvement of total daily physical activity. Secondary endpoint was: increase of physical performance tested by grip strength and 6-min walk test.

METHODS

Sixty eligible patients were randomly assigned to: arm 1, L-carnitine 4 g/day + Celecoxib 300 mg/day or arm 2, L-carnitine 4 g/day + celecoxib 300 mg/day + megestrol acetate 320 mg/day, all orally. All patients received as basic treatment polyphenols 300 mg/day, lipoic acid 300 mg/day, carbocysteine 2.7 g/day, Vitamin E, A, C. Treatment duration was 4 months. Planned sample size was 60 patients.

RESULTS

The results did not show a significant difference between tre atment arms in both primary and secondary endpoints. Analysis of changes from baseline showed that LBM (by dual-energy X-ray absorptiometry and by L3 computed tomography) increased significantly in both arms as well as physical performance assessed by 6MWT. Toxicity was quite negligible and comparable between arms.

CONCLUSIONS

The results of the present study showed a non-inferiority of arm 1 (two-drug combination) vs arm 2 (two-drug combination + megestrol acetate). Therefore, this simple, feasible, effective, safe, low cost with favorable cost-benefit profile, two-drug approach could be suggested in the clinical practice to implement CACS treatment.

L-Carnitine induces recovery of liver lipid metabolism in cancer cachexia

Cancer cachexia causes metabolic alterations with a marked effect on hepatic lipid metabolism. L-Carnitine modulates lipid metabolism and its supplementation has been proposed as a therapeutic strategy in many diseases. In the present study, the effects of L-carnitine supplementation on gene expression and on liver lipid metabolism-related proteins was investigated in cachectic tumour-bearing rats. Wistar rats were assigned to receive 1 g/kg of L-carnitine or saline. After 14 days, supplemented and control animals were assigned to a control (N), control supplemented with L-carnitine (CN), tumour-bearing Walker 256 carcinosarcoma (TB) and tumour-bearing supplemented with L-carnitine (CTB) group. The mRNA expression of carnitine palmitoyltransferase I and II (CPT I and II), microsomal triglyceride transfer protein (MTP), liver fatty acid-binding protein (L-FABP), fatty acid translocase (FAT/CD36), peroxisome proliferator-activated receptor-alpha (PPAR-alpha) and organic cation transporter 2 (OCTN2) was assessed, and the maximal activity of CPT I and II in the liver measured, along with plasma and liver triacylglycerol content. The gene expression of MTP, and CPT I catalytic activity were reduced in TB, who also showed increased liver (150%) and plasma (3.3-fold) triacylglycerol content. L-Carnitine supplementation was able to restore these parameters back to control values (p<0.05). These data show that L-carnitine preserves hepatic lipid metabolism in tumour-bearing animals, suggesting its supplementation to be of potential interest in cachexia.

l-carnitine and cancer cachexia: Clinical and experimental aspects

Cancer cachexia is a multifaceted syndrome characterized, among many symptoms, by extensive muscle wasting. Chronic systemic inflammation, partly triggered and sustained by cytokines, as well as increased oxidative stress contributes to the pathogenesis of this complex metabolic disorder. l-carnitine plays a central role in the metabolism of fatty acids and shows important antioxidant and anti-inflammatory properties. Systemic carnitine depletion has been described in several diseases, and it is characterized by fatigue, muscle weakness, and decreased tolerance to metabolic stress. In cachectic cancer patients, low serum carnitine levels have been reported, and this change has been suggested to play an important contributory role in the development of cachexia. Based on these data, carnitine supplementation has been tested in preliminary studies concerning human cachexia, resulting in improved fatigue and quality of life. We present here a review of clinical and experimental evidence regarding the use of carnitine supplementation in the management of cancer cachexia.

L-Carnitine and intestinal inflammation

The intestinal barrier is one of the most dynamic surfaces of the body. It is here where a single layer of epithelial cells mediates the intricate encounters that occur between the host's immune system and a multitude of potential threats present in the intestinal lumen. Several key factors play an important role in the final outcome of this interaction, including the state of oxidative stress, the level of activation of the immune cells, and the integrity of the epithelial barrier. This chapter describes the main evidence demonstrating the impact that l-carnitine has on each of these factors. These findings, combined with the demonstrated safety profile of l-carnitine, underscore the potential therapeutic value of l-carnitine supplementation in humans suffering from intestinal inflammation and highlight the functional data supporting an association between Crohn's disease and mutations in the l-carnitine transporter genes.

The antioxidant properties of carnitine in vitro

Many of the effects of carnitine are ascribed to its antioxidant properties. The aim of this study was to evaluate the antioxidant properties of carnitine in vitro. Carnitine was found to decolorize ABTS(*+), and to protect fluorescein against bleaching induced by AAPH-derived peroxyl radicals and peroxynitrite, thiol groups against oxidation induced by hydrogen peroxide, peroxyl radicals, hypochlorite and peroxynitrite, and erythrocytes against hemolysis induced by peroxyl radicals and hypochlorite. These results show that carnitine has a direct antioxidant action against physiologically relevant oxidants.

Pro-inflammatory and oxidative stress pathways which compromise sperm motility and survival may be altered by L-carnitine

The testis is an immunologically privileged organ. Sertoli cells can form a blood-testis barrier and protect sperm cells from self-immune system attacks. Spermatogenesis may be inhibited by severe illness, bacterial infections and chronic inflammatory diseases but the mechanism(s) is poorly understood. Our objective is to help in understanding such mechanism(s) to develop protective agents against temporary or permanent testicular dysfunction. Lipopolysaccaride (LPS) is used as a model of animal sepsis while L-carnitine (LCR) is used as a protective agent. A total of 60 male Swiss albino rats were divided into four groups (15/group). The control group received Saline; the 2(nd) group was given LCR (500 mg/kg i.p, once). The third group was treated with LPS (5 mg/kg i.p once) and the fourth group received LCR then LPS after three hours. From each group, five rats were used for histopathological examination. Biochemical parameters were assessed in the remaining ten rats. At the end of the experiment, animals were lightly anaesthetized with ether where blood samples were collected and testes were dissected on ice. Sperm count and motility were evaluated from cauda epididymis in each animal. Also, oxidative stress was evaluated by measuring testicular contents of reduced glutathione (GSH), malondialdehyde (MDA) and 8-hydroxydeoxyguanosine (8-HDG, the DNA adduct for oxidative damage) in testicular DNA. The pro-inflammatory mediator nitric oxide (NO) in addition to lactate dehydrogenase (LDHx) isoenzyme-x activity as an indicator for normal spermatozoal metabolism were assessed in testicular homogenate. Serum interlukin (IL)-2 level was also assessed as a marker for T-helper cell function. The obtained data revealed that LPS induced marked reductions in sperm's count and motility, obstruction in seminiferous tubules, hypospermia and dilated congested blood vessels in testicular sections concomitant with decreased testicular GSH content and LDHx activity. Moreover, the testicular levels of MDA, 8-HDG (in testicular DNA) and NO as well as serum IL-2 level were increased. Administration of LCR before LPS returned both sperm count and motility to normal levels. Also, contents of testicular GSH, MDA, 8-HDG and NO returned back to the corresponding control values. In addition, serum IL-2 level as well as histological abnormalities were markedly improved in LCR + LPS-treated rats. In conclusion, LPS increased proinflammatory and oxidative stress markers in the testis leading to a marked testicular dysfunction. L-carnitine administration ameliorates these effects by antioxidant and/or anti-inflammatory mechanisms suggesting a protective role against male infertility in severely infected or septic patients.

Dietary L-carnitine supplementation increases antigen-specific immunoglobulin G production in broiler chickens

The usefulness of supplementary dietary L-CARNITINE AS AN IMMUNOMODULATOR TO INCREASE ANTIGEN-SPECIFIC ANTIBODY LEVELS WAS ANALYSED IN 2–6-WEEK-OLD BROILERS. THE CHICKENS RECEIVED COMMERCIAL FEEDS EITHER UNSUPPLEMENTED (STARTER FEED 17·8 MG CARNITINE/KG, FINISHER DIET 22·9 MG CARNITINE/KG) OR SUPPLEMENTED WITH l-carnitine (100 mg carnitine/kg added to feed). At 14 d of age, both groups were distributed in equal numbers and sex ratios over two environmentally controlled chambers where temperature (28°) was either reduced immediately to 20°, or gradually to 22° at 36 d of age. Antigen-specific immunoglobulin (Ig)M, IgG, IgA and total Ig responses were measured following two immunizations with bovine serum albumin (BSA). The typical BSA-specific IgM responses followed by IgG responses to the primary immunization were boosted by the secondary immunization. The kinetics of these responses were not altered by l-carnitine treatment. However, BSA-specific total Ig and IgG, but not IgM, responses were significantly increased by dietary l-carnitine supplementation, after both the primary and the secondary immunization. No significant influence of the sex of the chicks or the imposed environmental temperature on Ig responses was found. Temperature treatment and sex, but not l-carnitine supplementation, did significantly influence body-weight gain: cockerels were heavier than females and this became most evident in the second half of the rearing period. Further, lowering the temperature increased body weight. In conclusion, dietary l-carnitine supplementation appeared to be beneficial in enhancing specific humoral responses on vaccination.

Delayed acetyl-l-carnitine administration and its effect on sensory neuronal rescue after peripheral nerve injury

Protection of sensory neurons after peripheral nerve injury is clinically crucial since inadequate sensory recovery is seriously affected by the death of up to 40% of sensory neurons. Immediate acetyl-L-carnitine (ALCAR) treatment eliminates this cell loss, but may not always be clinically feasible, hence we studied the effect of delaying the initiation of ALCAR treatment. Five groups of rats (n=5 per group) underwent unilateral sciatic nerve axotomy. ALCAR treatment (50 mg/kg/day) was initiated immediately, or after delays of 6 h, 24 h or 7 days after injury. A sham-treated group served as control. L4 and L5 dorsal root ganglia were harvested bilaterally 2 weeks after injury and stereological sensory neuron counts were obtained. Immediate sham treatment provided no neuroprotection (25% loss). Cell loss was eliminated when ALCAR was commenced within<or=24 h of axotomy. No statistically significant neuroprotective effect (18% loss) was evident compared to sham when ALCAR administration was initiated 7 days post-axotomy. When commenced within a clinically applicable time frame ALCAR treatment remains highly neuroprotective, potentially improving clinical outcome following peripheral nerve trauma.

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.

Reduction of glutamate levels in HIV-infected subjects treated with acetylcarnitine

The excitotoxic amino acid glutamate, which is elevated in blood and cerebrospinal fluid from subjects with AIDS dementia complex, is crucially implicated in the neurotoxicity of HIV infection. We describe a subject with AIDS dementia complex who showed a significant motor and cognitive improvement after a course of intravenous acetylcarnitine therapy. The clinical improvement was paralleled by a significant reduction of glutamate concentrations in both blood and cerebrospinal fluid. A prospective pilot study confirmed that acetylcarnitine administration resulted indeed to reduce the blood levels of glutamate in AIDS patients treated with acetylcarnitine therapy in order to prevent the neurotoxicity of nucleoside analogs. Even though the mechanisms responsible for the reduction of glutamate concentrations remain to be established, we suggest that acetylcarnitine should be added to the list of drugs under investigation for the treatment of AIDS dementia complex. The anti-apoptotic activity of carnitines and their safety profile further support this view.

L-Carnitine L-tartrate (LCLT) and dehydroepiandrosterone sulfate (DHEAS) affect red and white blood cells in aged Sprague-Dawley rats

Supplementation with either L-carnitine or DHEAS was separately suggested to counteract age-related declines. However, little is known about any interactive effects of these substances, independently promoting mitochondrial energy metabolism, in older individuals. We thus studied the effects of 3 months of daily oral combined supplementation with LCLT and DHEAS on red (RBCs) and white blood cells (WBCs) in male Sprague-Dawley rats by determining RBC and WBC counts, lymphocyte proliferation and interleukin-2 (IL-2) synthesis in spleen lymphocytes after Concanavalin A (ConA) stimulation. Supplementation with LCLT in addition to DHEAS decreased RBCs and increased platelets in the blood of 25-month-old Sprague-Dawley rats, whereas supplementation with DHEAS alone shifted the balance from segmented neutrophile granulocytes to large lymphocytes in differential WBC counts. Based on these results, interactive effects of supplementation with L-carnitine and DHEAS on RBCs and platelets are suggested.

Constitutive or induced elevated levels of l-carnitine correlate with the cytokine and cellular profile of endometriosis

During the past decade, accumulated evidence indicates an association between endometriosis and an alteration of humoral and cell-mediated immunity. While the role of L-carnitine in the regulation of energy metabolism is well established, it is only recently that L-carnitine has been recognized to modify the immune response in mice after in vitro or in vivo treatment. The present study has examined whether administration of L-carnitine to young female mice alters the percentage of immune cells in peritoneal exudates and the uterus as well as the levels of IFN-gamma, TNF-alpha, IL-2, IL-4, IL-6, VEGF, GM-CSF and IGF-I in blood serum, peritoneal fluid and supernatants of uterine cultured cells as tested by immunofluorescence or ELISA techniques, respectively, leading to a pathological disorder resembling human endometriosis. The results showed that, except from infertility, L-carnitine treatment resulted in a significant increase of macrophages and to a lesser degree an increase of T-cells, while elevated levels of IFN-gamma and TNF-alpha were detected in both serum and peritoneal fluid compared to controls. Although levels of L-carnitine measured in mouse serum samples using a radioisotopic method showed an increase as compared to controls, levels of acyl-L-carnitine measured in the murine peritoneal fluid samples showed a decrease similar to that measured in peritoneal fluid samples from patients with endometriosis in stage IV of the disease. These results indicate that L-carnitine administration to female mice alters the cellular and growth factor profile in the uterus and peritoneum towards a phenotypical pathology similar to that of clinical endometriosis.

L-carnitine infusions may suppress serum C-reactive protein and improve nutritional status in maintenance hemodialysis patients

Scattered reports indicate that L-carnitine may suppress proinflammatory cytokines in sick individuals without renal disease and may improve protein synthesis or nitrogen balance either in patients without renal disease or in maintenance hemodialysis (MHD) or chronic peritoneal dialysis patients. We conducted an experimental study in MHD patients to evaluate the effects of L-carnitine treatment on inflammatory and protein-energy nutritional status. MHD patients were assigned to receive intravenous injections of L-carnitine 20 mg/kg (n = 48) or placebo (n = 65) thrice weekly at the end of each hemodialysis treatment for 6 months. The carnitine-treated group showed a statistically significant decrease in serum C-reactive protein and increase in serum albumin and transferrin, blood hemoglobin, and body mass index. Conversely, in the placebo-treated group, a significant decrease was reported for serum albumin, serum transferrin, and body mass index, whereas the other considered measures did not change significantly. These preliminary findings suggest that in MHD patients, L-carnitine therapy may suppress inflammation, particularly among those patients with C-reactive protein > or =3 mg/dL, and may improve protein-energy nutritional status.

Supplementation of L-carnitine in athletes: does it make sense?

Studies in athletes have shown that carnitine supplementation may foster exercise performance. As reported in the majority of studies, an increase in maximal oxygen consumption and a lowering of the respiratory quotient indicate that dietary carnitine has the potential to stimulate lipid metabolism. Treatment with L-carnitine also has been shown to induce a significant postexercise decrease in plasma lactate, which is formed and used continuously under fully aerobic conditions. Data from preliminary studies have indicated that L-carnitine supplementation can attenuate the deleterious effects of hypoxic training and speed up recovery from exercise stress. Recent data have indicated that L-carnitine plays a decisive role in the prevention of cellular damage and favorably affects recovery from exercise stress. Uptake of L-carnitine by blood cells may induce at least three mechanisms: 1) stimulation of hematopoiesis, 2) a dose-dependent inhibition of collagen-induced platelet aggregation, and 3) the prevention of programmed cell death in immune cells. As recently shown, carnitine has direct effects in regulation of gene expression (i.e., carnitine-acyltransferases) and may also exert effects via modulating intracellular fatty acid concentration. Thus there is evidence for a beneficial effect of L-carnitine supplementation in training, competition, and recovery from strenuous exercise and in regenerative athletics.

Carnitine replacement in end-stage renal disease and hemodialysis

In patients with chronic renal failure, not yet undergoing hemodialysis (HD), plasma acylcarnitines accumulate in part due to a decreased renal clearance of esterified carnitine moieties. In these patients, a high acylcarnitine/free-carnitine ratio is usually found in plasma. Patients undergoing maintenance HD, usually present with plasma carnitine insufficiency, due to accumulation of metabolic intermediates combined with impaired carnitine biosynthesis, reduced protein intake and increased removal via HD. Plasma carnitine concentrations rapidly decrease to 40% of baseline level during the dialysis session, with a slow restoration of the carnitine concentration during the interdialytic period, mainly from organs of storage (skeletal muscle). Dietary intake also plays an important role in carnitine homeostasis of HD patients since the prevalence of malnutrition ranges from 18% to 75% of these cases. This could differentially affect various body compartments, with clinical consequences such as impaired muscle function, decreased wound healing, altered ventilatory response, and abnormal immune function. Repeated hemodialytic treatments are associated with decreased carnitine stores in skeletal muscle. The administration of intravenous L-carnitine (LC) postdialysis replenishes the free carnitine removed from the blood and contributes to replenishment of muscle carnitine content. LC supplementation in selected uremic patients may yield clinical benefits by ameliorating several conditions, such as erythropoietin-resistant anemia, decreased cardiac performance, intradialytic hypotension, muscle symptoms, as well as impaired exercise and functional capacities. Furthermore, LC may positively influence the nutritional status of HD patients by promoting a positive protein balance, and by reducing insulin resistance and chronic inflammation, possibly through an effect on leptin resistance.

Carnitines and its congeners: a metabolic pathway to the regulation of immune response and inflammation

Carnitine and its congeners may regulate the immune networks, and their influence on functions of immune cells predominantly or exclusively relies on carnitine-dependent energy production from fatty acids. A reduced pool of carnitines has been demonstrated in either serum or tissues, or both, from patients with a wide spectrum of disorders characterized by unregulated or impaired immune responses ranging from sepsis syndrome to systemic sclerosis, infection with human immunodeficiency virus, and chronic fatigue syndrome. Furthermore, experimental studies have consistently reported that the deranged immune responses and the less efficient inflammation towards infectious organisms associated with aging may be enhanced or modulated by treatment with carnitines. There is also evidence that carnitine deprivation could adversely affect the course of the sepsis syndrome, at least in experimental models, and preliminary studies suggest that carnitine deficiency is ultimately implicated in the pathophysiology of endotoxin-mediated multiple organ failure. Several data indicate that carnitine deficiency is a contributing factor to the progression of infection with human immunodeficiency virus, and carnitine therapy in those patients could counteract the unregulated process of lymphocyte apoptosis and improve CD4 counts. Some case reports have suggested the use of carnitine for the treatment of the severe lactic acidosis that complicates in some patients the use of reverse transcriptase inhibitors.

Role of carnitine in modulating acute-phase protein synthesis in hemodialysis patients

Increased serum levels of C-reactive protein (CRP) in uremic and dialysis patients are associated with low serum prealbumin and albumin concentrations and increased mortality and greater risk of cardiovascular disease. Proinflammatory cytokines may cause malnutrition by increasing protein catabolism. Many studies have shown that L-carnitine supplementation leads to improvements in several conditions seen in uremic patients, including cardiac complications, impaired exercise and functional capacities, muscle symptoms, increased symptomatic intradialytic hypotension, and erythropoietin-resistant anemia. L-carnitine therapy may either suppress the inflammatory response or act independently on both inflammation and appetite and/or anabolic processes. Moreover, L-carnitine may suppress proinflammatory cytokines in sick individuals without renal disease and may improve protein synthesis or nitrogen balance in patients without renal disease and in hemodialysis and peritoneal dialysis patients. In a pilot study, we provided preliminary evidence that treatment with L-carnitine, 20 mg/kg 3 times weekly at the end of each hemodialysis treatment, was associated with a reduction in serum CRP levels and improvement in anabolic status. The improvement or normalization of serum concentrations of serum CRP also was correlated with increased serum concentrations of albumin, transferrin, and blood hemoglobin. The possibility that some or all of these changes may have been caused by improved nutritional intake cannot be ruled out. Further randomized clinical trials will be necessary to confirm the role of L-carnitine as a modulator of inflammatory protein synthesis in hemodialysis patients.

Modulatory Effects of l-Carnitine on Glucocorticoid Receptor Activity

L-carnitine (3-hydroxy-4-N,N,N-trimethylaminobutyrate) is a conditionally essential nutrient with a major role in cellular energy metabolism. It is available in the United States as both a prescription drug and an over-the-counter nutritional supplement. Accumulating evidence from both animal and human studies indicates that pharmacologic doses of L-carnitine (LCAR) have immunomodulatory effects resembling those of glucocorticoids (GC). On the other hand, in contrast to GC, which cause bone loss, LCAR seems to have positive effects on bone metabolism. To explore the molecular bases of this GC-like activity of LCAR, we investigated its effects on glucocorticoid receptor (GR)-modulated cytokine release ex vivo, and on the transcriptional activity, intracellular trafficking, and binding of GR in vitro. At high noncytotoxic doses, LCAR (a) suppressed the lipopolysaccharide-stimulated release of tumor necrosis factor alpha and interleukin-12 from primary human monocytes in a GC-like fashion, (b) stimulated the transcriptional activity of GR on the GC-responsive promoters, (c) triggered nuclear translocation of green fluorescent protein (GFP)-fused GR, and (d) reduced the whole cell binding of [(3)H]-dexamethasone to GR. These results suggest that LCAR is a "nutritional modulator" of the GR, by acting as an agonist-like compound. Since LCAR appears to have positive effects on bone metabolism, in contrast to GC, LCAR may share some of the therapeutic properties of GC, particularly on the immune system, but not their deleterious side effects on some of other organs/tissues. Thus, LCAR is potentially a useful alternative compound of GC in particular therapeutic situations. The clinical and therapeutic implications of these findings, as well as a better understanding of their mechanisms, warrant further research.

Carnitine system in uremic patients: Molecular and clinical aspects

Carnitine is a small water-soluble molecule that is present in almost all animal species. It plays an indispensable role in fatty acid metabolism, where it is involved in the transport of activated fatty acids between different cellular compartments. Uremic patients, as well as patients with chronic renal failure, appear to have abnormal renal handling of carnitine leading to dyslipidemia, lethargy, muscular weakness, hypotension, cardiac dysfunction and arrhythmias, and recurrent cramps. It often is difficult to distinguish these symptoms from similar ones related to uremia and dialysis. Many investigators have advocated L-carnitine supplementation in an attempt to alleviate carnitine deficiencies, and good results from this therapy have been reported. Moreover, several studies have shown that L-carnitine supplementation improves the response to erythropoietin. Chronic inflammation is another particular aspect affecting these patients. Anti-inflammatory properties of L-carnitine in hemodialysis patients have been shown by our group. Treatment with L-carnitine (20 mg/kg, given intravenously at the end of each dialysis session for 6 mo), significantly decreased serum C-reactive protein (CRP) levels, a proinflammatory cytokine known to inhibit erythropoiesis. Moreover, data from published literature are indicative of L-carnitine modulation of the immune system by the activation of glucocorticoid receptors and the modulation of the transcription of glucocorticoid-responsive genes. Our study showed that in these patients, treatment with L-carnitine has been able to improve their body mass index, likely by promoting a positive protein balance. This aspect is strictly correlated with the status of insulin resistance, which is well described in patients with renal diseases. Many studies showed that carnitine allowed mitochondrial fatty acid usage to link to the rate of glucose usage, thus improving insulin resistance. In conclusion, clinical beneficial effects of L-carnitine treatment on patients suffering from renal diseases are supported by molecular evidence involving both inflammatory and metabolic aspects of the disease.

Acetyl-l-carnitine: a pathogenesis based treatment for HIV-associated antiretroviral toxic neuropathy

BACKGROUND

Nucleoside analogue reverse transcriptase inhibitors (NRTI) disrupt neuronal mitochondrial DNA synthesis, impairing energy metabolism and resulting in a distal symmetrical polyneuropathy (DSP), an antiretroviral toxic neuropathy (ATN) that causes significant morbidity in HIV disease. Serum acetyl-l-carnitine (ALCAR) levels are decreased in neuropathy associated with NRTI therapy. ALCAR enhances neurotrophic support of sensory neurons and promotes energy metabolism, potentially causing nerve regeneration and symptom relief.

OBJECTIVE

To assess the efficacy of oral ALCAR (1500 mg twice daily) for up to 33 months in an open cohort of 21 HIV-positive patients with established ATN.

METHODS

Skin biopsies were excised from the leg before ALCAR treatment, at 6-12 month intervals thereafter and from HIV-negative non-neuropathic controls. Fibre types in epidermal, dermal and sweat gland innervation were quantified immunohistochemically.

RESULTS

After 6 month's treatment, mean immunostaining area for small sensory fibres increased (epidermis 100%, P = 0.006; dermis 133%, P < 0.05) by more than that for all fibre types (epidermis 16%, P = 0.04; dermis 49%, P < 0.05; sweat glands 60%, P < 0.001) or for sympathetic fibres (sweat glands 41%, P < 0.0003). Compared with controls, epidermal, dermal and sweat gland innervation reached 92%, 80% and 69%, respectively, after 6 month's treatment. Innervation improvements continued (epidermis and dermis) or stabilized (sweat glands) after 24 month's treatment. Neuropathic grade improved in 76% of patients and remained unchanged in 19%. HIV RNA load, CD4 and CD8 cell counts did not alter significantly throughout the study.

CONCLUSIONS

ALCAR treatment improves symptoms, causes peripheral nerve regeneration and is proposed as a pathogenesis-based treatment for DSP.

l-Carnitine Is a Modulator of the Glucocorticoid Receptor Alpha

L-Carnitine (LC) is a nutrient with an essential role in cellular energy production. At high doses, LC can mimic some of the biological activities of glucocorticoids, particularly immunomodulation. To explore the molecular bases of this property, we tested the influence of LC on glucocorticoid receptor-a (GRalpha) functions. LC reduced the binding capacity of GRalpha, induced its nuclear translocation, and stimulated its transcriptional activity. Moreover, LC suppressed TNFalpha and IL-12 release from human monocytes in glucocorticoid-like fashion. We conclude that pharmacologic doses of LC can activate GRalpha and, via this mechanism, regulate glucocorticoid-responsive genes, potentially sharing some of the biological and therapeutic properties of glucocorticoids.

Low serum carnitine in HIV-infected children on antiretroviral treatment

OBJECTIVE

HIV-infection and antiretroviral therapies are associated with energy dysfunction and lipid metabolism in adults. Our aim was to detect a possible carnitine deficiency in HIV-infected children on antiretroviral treatments. We analysed the relation among serum carnitine, its amino-acid precursors (methionine and lysine), clinical evaluation and antiretroviral therapy.

DESIGN AND SETTING

Cross-sectional study performed in a tertiary care hospital.

SUBJECTS

A total of 79 HIV-infected children on antiretroviral therapy, monitored prospectively in our hospital.

INTERVENTIONS

Antiretroviral therapy included nucleoside analogues plus protease inhibitors and/or non-nucleoside analogues. Carnitine was analysed by an enzymatic-spectrometric procedure, and amino acids by ion exchange chromatography. Reference values of carnitine and amino acids were established in apparently healthy children who underwent presurgical analysis for minor surgery.

RESULTS

Serum free and total carnitine, acylcarnitines, methionine and lysine were significantly lower in HIV-infected children compared with our reference values for similar ages (P<0.0001; Student's t-test). Low carnitine values were observed in 37% of our HIV-infected children. A significantly positive correlation was observed between serum total carnitine and methionine or lysine (P<0.0001 and P=0.005, respectively; Pearson test). No relation was observed between serum carnitine and clinical stage of HIV infection, immunological or nutritional status or lipodystrophy. Free and total carnitine were significantly lower (P=0.002 and 0.033, respectively) in HIV-infected patients on protease inhibitors (N=56) compared with those on other treatments (N=23).

CONCLUSIONS

Low serum carnitine concentration was observed in 37% of our HIV-infected children on antiretroviral therapy. Malabsorption or defective synthesis may also account for the low serum carnitine values detected in these patients.

L-carnitine alleviates alcohol-induced liver damage in rats: role of tumour necrosis factor-alpha

AIMS

Excessive alcohol intake induces hepatic fatty infiltration, which has been suggested to sensitize the liver to further damage. To test this hypothesis, L-carnitine, a constitutional lipotropic compound, was administered to rats chronically treated with ethanol by liquid diet feeding for 10 weeks.

RESULTS

Ethanol administration caused marked steatosis, mild inflammation and elevated plasma alanine aminotransferase and tumour necrosis factor alpha (TNF-alpha) concentrations. Dietary supplementation with L-carnitine significantly reduced all these parameters as well as the hepatic concentration of thiobarbituric acid reactive substances, an indicator of lipid peroxidation products. Pretreatment with L-carnitine also significantly blunted ethanol-induced stimulation of TNF-alpha release by isolated Kupffer cells.

CONCLUSIONS

This study provides direct support for the notion that steatosis sensitizes the liver to further damage and suggests an involvement of TNF-alpha in this process.

L-carnitine: A nutritional modulator of glucocorticoid receptor functions

L-carnitine is an essential nutrient with a major role in cellular energy production. There is evidence that, at high doses, L-carnitine might mimic some of the biological activities of glucocorticoids, especially immunomodulation. To explore the molecular basis of this effect, we tested the influence of L-carnitine on glucocorticoid receptor-alpha (GRalpha) functions. Millimolar concentrations of L-carnitine, which were not cytotoxic in vitro, significantly reduced the whole cell binding of [3H]dexamethasone to GRalpha by decreasing the affinity of this receptor for its steroid ligand. At the same concentrations, L-carnitine was able to trigger nuclear translocation of green fluorescent protein (GFP)-fused human GRalpha and transactivate the glucocorticoid-responsive mouse mammary tumor virus (MMTV) and TAT3 promoters in a dose-dependent fashion. This effect was solely dependent on the presence of glucocorticoid-responsive elements on the promoter and on the expression of functional GRalpha by the cell. Finally, similarly to glucocorticoids, L-carnitine suppressed tumor necrosis factor-alpha (TNFalpha) and interleukin-12 release by human primary monocytes stimulated with lipopolysaccharide ex vivo. Both GRalpha transactivation and cytokine suppression by L-carnitine were abrogated by the GRalpha-antagonist RU 486. Taken together, our results suggest that pharmacological doses of L-carnitine can activate GRalpha and, through this mechanism, regulate glucocorticoid-responsive genes, potentially sharing some of the biological and therapeutic properties of glucocorticoids.

Relative contributions of nutrition and inflammation to clinical outcome in dialysis patients

Protein-energy malnutrition (PEM) is a common phenomenon in maintenance dialysis (MD) patients and a risk factor for poor quality of life and increased morbidity and mortality, including cardiovascular death, in these individuals. The association between undernutrition and adverse outcome in MD patients, which stands in contrast to that seen in the general population, has been referred to as reverse epidemiology. Measures of food intake, body composition tools, nutritional scoring systems, and laboratory values are used to assess the degree of severity of PEM, but no uniform approach is available for rating the overall severity of PEM. Epidemiologic studies suggest that inflammation is a missing link between PEM and poor clinical outcome in MD patients, and the existence of a malnutrition inflammation complex syndrome is suggested in these patients. Inflammation may be due to subclinical and clinically apparent illnesses. Some investigators suggest that PEM may predispose to illness and inflammation. There is a paucity of information concerning the effect of nutritional therapy on morbidity and mortality in MD patients. Interventional studies of the effect of nutritional support on outcome often are difficult to interpret because of small sample sizes, short duration of study, and other limitations. Large-scale, randomized, clinical trials of the effects of nutritional intake, nutritional status, and inflammation on clinical outcome are needed to define better the relationships between these factors in MD patients.

L-carnitine modifies the humoral immune response in mice after in vitro or in vivo treatment

Although the role of L-carnitine (L-Cn) as a cofactor in the oxidation of long-chain fatty acids has been well established, this agent has also been recognized to have an important role in the regulation of carbohydrate metabolism, and consequently, the maintenance of cell membrane structure and cell viability. L-Cn has been reported to reduce the apoptotic levels of CD4+ and CD8+ cells. It has also been demonstrated to interfere with cells of the monocytic lineage by regulating their ability to produce growth factors that ultimately affect both T and B lymphocytic subsets. Therefore, in this study, we examined whether this agent affects the antigenic response of immune cells and determined the relative numbers of immune cells in the murine spleen after in vitro and in vivo treatment. The results showed that L-Cn reduces the relative numbers of CD8+, CD4+ and Ly5+ cells. This observation was consistent in all systems studied including (a) in vitro inoculation of antigen (DNP-HSA) and L-Cn, (b) in vitro priming of spleen cells treated with L-Cn in vivo, and (c) in vivo immunization and L-Cn administration. In all cases, the reduction of T lymphocytes correlated with the decreased production of interleukin-2. L-Cn, however, did not affect the production of specific antibody, which indicates that the observed reduction of Ly5-positive cells is due to cell differentiation of B cells to plasma cells.

Continuous ambulatory peritoneal dialysis (CAPD) adequacy influences serum free carnitine level

OBJECTIVE

An evaluation of serum free carnitine level in CAPD patients in relation to dietary intake, nutritional status and CAPD adequacy and duration.

STUDY DESIGN

Food diaries, nutritional (total body mass, lean body mass, serum level of proteins, carnitine, cholesterol) and adequacy (Kt/V, PCR, tCcr, EN) parameters were obtained in 23 CAPD patients.

RESULTS

Normal carnitine level (41.8+/-6.7 micromol/l) was found in 17 patients being on CAPD through 11.1+/-9.6 months, whereas in 6 persons treated with CAPD through 9.7+/-4.1 months carnitine level was 25.4+/-5.7 micromol/l. Significant differences between low and normal carnitine groups were in tCcr (82.7+/-16.7 v. 65.9+/-13.2 l/wk/1.73 m2 BSA), effluent volume (10.9+/-0.8 v. 9.9+/-1.5 l/day), effluent glucose concentration (729+/-167 v. 530+/-220 mg/dl) and serum globulin level (22.6+/-6.4 v. 29.3+/-4.4 g/l). Significant correlation coefficients (for n = 23) were found between serum carnitine level and effluent volume (r=-0.509) or plasma globulin level (r=+0.522).

CONCLUSION

Patients with higher CAPD adequacy show lower serum free carnitine levels and this is related to higher effluent volumes.