Sonia Marcellini

Acetyl-carnitine deficiency in Aids patients with neurotoxicity on treatment with antiretroviral nucleoside analogues

Objective:A severe dose-limiting axonal peripheral neuropathy may develop in subjects on treatment with the nucleoside analogues didanosine (ddI), zalcitabine (ddC), and stavudine (d4T). The impairment of mitrochondrial DNA synthesis is crucial to the pathogenesis of this disorder although other mechanisms have not been ruled out. The depletion of acetyl-carnitine, which regulates the metabolism and function of peripheral nerves, could contribute to the neurotoxicity of these compounds. Design:Non-randomized, cross-sectional study of selected patients. Methods:We measured the serum levels of acetyl- and total carnitine in 12 subjects with axonal peripheral neuropathy developed on treatment with different regimens of neurotoxic nucleoside analogues (ddI, ddC, d4T). Subjects who did not develop peripheral neuropathy while staying on treatment with ddI (n = 10) or zidovudine (n = 11) served as the control groups. HIV-negative subjects with axonal or demyelinating autoimmune neuropathies (n = 10) and healthy individuals (n = 13) were additional control groups. Results:Subjects experiencing axonal peripheral neuropathy on treatment with ddI, ddC and d4T had significantly reduced levels of acetyl-carnitine in comparison to the control groups. No difference was observed in the levels of total carnitine between study subjects and the control groups. Conclusions:Our results demonstrate that subjects who developed peripheral neuropathy while staying on treatment with ddI, ddC and d4T had acetyl-carnitine deficiency. The normal levels of total carnitine in the study group appear to indicate the specificity of the defect and rule out coexisting relevant nutritional problems. The critical role of acetyl-carnitine for the metabolism and function of the peripheral nerves supports the view that the acetyl-carnitine deficiency found in these subjects may contribute to the neurotoxicity of ddI, ddC and d4T, even though the interference with mitochondrial DNA synthesis is regarded as the main cause of their toxicity.

L-Carnitine Reduces Lymphocyte Apoptosis and Oxidant Stress in HIV-1-Infected Subjects Treated with Zidovudine and Didanosine

Apoptosis is critical to the progression of human immunodeficiency virus-1 (HIV-1) infection. It appears reasonable that antiretroviral therapies may not achieve a full control of the infection in the absence of an impact on apoptosis. We assigned 20 asymptomatic HIV-infected subjects with advanced immunodeficiency to receive either zidovudine (AZT), and didanosine (DDI) or the same regimen plus L-carnitine, a known antiapoptotic drug, for 7 months. Immunologic and virologic parameters were measured at baseline and after 15, 60, 120, and 210 days of treatment. We assessed on each time point the following: (a) the frequency of peripheral blood apoptotic CD4 and CD8 lymphocytes, CD4 and CD8 cells with disrupted mitochondrial membrane potential, and CD4 and CD8 cells undergoing oxidant stress; (b) the expression of the molecular markers of apoptosis Fas and caspase-1; and (c) the expression of p35/cdk-5 regulatory subunit that is involved in regulating cell survival and apoptosis. Absolute CD4 and CD8 counts and plasma viremia were also measured. Apoptotic CD4 and CD8 cells, lymphocytes with disrupted mitochondrial membrane potential, and lymphocytes undergoing oxidant stress were greatly reduced in subjects treated with AZT and DDI plus L-carnitine compared with those who did not receive L-carnitine. Fas and caspase-1 were down-expressed and p35 over-expressed in lymphocytes from patients of the L-carnitine group. No difference was found in CD4 and CD8 counts and viremia between the groups. No toxicity of L-carnitine was recognized. The addition of L-carnitine is safe and allows apoptosis and oxidant stress to be greatly reduced in lymphocytes from subjects treated with AZT and DDI.

Apoptosis and apoptosis-associated perturbations of peripheral blood lymphocytes during HIV infection: comparison between AIDS patients and asymptomatic long-term non-progressors

This study was designed to compare the degree of lymphocyte apoptosis and Fas–Fas ligand (FasL) expression in AIDS patients and long‐term non‐progressors (LTNPs) and correlate these parameters with apoptosis‐associated perturbations in lymphocyte function. LTNPs had a lower frequency of apoptotic CD4+ and CD8+ T cells compared with subjects with AIDS. This correlated with a lower frequency of cells expressing Fas and FasL. The frequency of selected lymphocyte populations exhibiting a disrupted mitochondrial transmembrane potential (ΔΨm) and increased superoxide generation was lower in LTNPs than in patients with AIDS; these abnormalities were associated with lower levels of caspase‐1 activation in LTNPs. The results indicate a significantly reduced level of apoptosis and apoptosis‐associated parameters in LTNPs than in patients developing AIDS. Based on these findings, a crucial role for mitochondria can be predicted in the process of lymphocyte apoptosis during the evolution of AIDS.

Modulation of apoptosis and improved redox metabolism with the use of a new antioxidant formula.

Oxidative stress is involved in the pathogenesis of a wide spectrum of diseases, implicating that strategies directed at counterbalancing oxidative processes could have a role in clinical medicine. There is also an evidence that oxidative stress acts as a major determinant of apoptotic cell death. Many studies have reported favourable effects of antioxidant formulas on several parameters of the oxidant-antioxidant balance, but none of them has focused whether antioxidant formulas could modulate apoptosis. We investigated in 20 healthy individuals the effect of supplementation with a formula containing alpha-tocopherol, alpha-lipoic acid, coenzyme Q(10), carnitines, and selenomethionine, on plasma oxidant status and peroxide levels, erythrocyte antioxidant enzymes, lymphocyte apoptosis, and generation of ROS at the mitochondrial level. Control subjects received only carnitines or an incomplete formula with alpha-tocopherol, alpha-lipoic acid, coenzyme Q(10), and selenomethionine. Supplementation with the complete formula resulted in a significant increase in the plasma antioxidant status that was mirrored by a decrease in blood peroxide levels and a reduced generation of ROS at the mitochondrial level. This was associated with a significant decrease in the frequency of peripheral blood lymphocytes, with either CD4 or CD8 phenotype, undergoing apoptosis. Less consistent results were found when either incomplete formula was used. Our study suggests that supplementation with antioxidant formulas can modulate the process of apoptosis under in vivo conditions. The clinical potential of this strategy in the treatment of diseases with an elevated commitment to apoptosis should be explored.

Apoptosis: mechanisms and relation to AIDS

Infection with the human immunodeficiency virus (HIV) is considered to lead to the acquired immunodeficiency syndrome (AIDS) via the progressive loss of immune competence in the infected host. Recent research has highlighted that HIV may indirectly trigger an active cell suicide process, referred to as programmed cell death or apoptosis, that contributes to the decline in lymphocyte counts throughout the course of HIV infection. We review here the main host- and HIV-related factors actively involved in inducing lymphocyte apoptosis. Among them, the relationships linking HIV, the oxidant/antioxidant balance in the cellular redox system, tumor necrosis factor (TNF) and lymphocyte-associated ceramide generated through the activation of sphingomyelin pathway are receiving growing consideration. Recognizing the importance of apoptosis in AIDS pathogenesis may have a great impact on the design of new strategies for the treatment of the disease. Available data indicate that antioxidant compounds exert antiapoptotic activity. These compounds, in our opinion, should be used in combination regimens with antiretroviral drugs in the treatment of HIV-infected subjects.

5-S-Cysteinyl-dopamine effect on the human dopaminergic neuroblastoma cell line SH-SY5Y

In recent years a catechol-thioether metabolite of dopamine, 5-S-cysteinyl-dopamine, has been identified in certain dopaminergic regions of the brain, notably the Substantia Nigra. 5-S-Cysteinyl-dopamine has received great attention in view of its possible significance as an index of oxidative stress in aging and in neurodegenerative processes, particularly in Parkinsons disease. In the present study the effect of 5-S-cysteinyl-dopamine on human dopaminergic neuroblastoma SH-SY5Y cells is investigated. The substance is highly cytotoxic, even at a concentration as low as 30 microM. Treatment of the cells with 5-S-cysteinyl-dopamine induce the following intracellular responses: a decrease of the mitochondrial transmembrane potential, an increase in reactive oxygen species such as superoxide anion and peroxides, a marked decrease of reduced glutathione and an inhibition of the complex I activity. Caspase-3-like protease activation and oligonucleosomal DNA fragmentation have also been observed. These data are indicative of the onset of apoptotic processes due to 5-S-cysteinyl-dopamine.

Abnormalities of carnitine metabolism in chronic fatigue syndrome.

Carnitine may be involved in the pathogenesis of the chronic fatigue syndrome (CFS). However, no information about the cellular metabolism of carnitine in CFS patients is currently available. Therefore, we aimed to measure the levels of carnitine (total, free and short‐chain) in both peripheral blood lymphocytes (PBLs) and sera from patients with CFS. The serum levels of total, free and short‐chain were comparable in CFS patients, considered as the whole group, to those in healthy control subjects, even though a trend indicating slightly reduced serum concentrations of free carnitine was observed in male patients with CFS. In contrast, the concentrations of total, free and short‐chain carnitine in PBLs from patients with CFS were significantly lower than in cells from healthy controls. Our study indicates that patients with CFS require exogenous carnitine supplementation. The low carnitine concentrations in PBLs from patients with CFS probably reflect the carnitine deficiency occurring in other tissues, including the skeletal muscles. The low cellular concentrations of carnitines may help to explain both the immunological abnormalities and the impaired energy metabolism in skeletal muscles.

Combined antiviral therapy reduces HIV-1 plasma load and improves CD4 counts but does not interfere with ongoing lymphocyte apoptosis.

The progression of HIV-1 disease appears associated with an unregulated Fas-mediated apoptosis of lymphocytes that involves the activation of ICE protease and ceramide generation and antiviral therapy may not be fully effective in the absence of a relevant impact on apoptosis. Six drug-naive HIV-1-infected symptomless patients with advanced immunodeficiency were treated with combined AZT and ddl for 4 months; plasma HIV-1 RNA levels, the counts of CD4 cells, CD4 and CD8 apoptotic lymphocytes, Fas-positive cells and ICE-positive cells, and intracellular ceramide levels were measured at base-line and after 7, 45 and 120 days of treatment. There was a prompt reduction in plasma viremia and a secondary increase in CD4 counts, but the treatment had no impact on apoptotic CD4 and CD8 lymphocytes, Fas-positive cells and ICE-positive cells, and on the intracellular levels of ceramide. A discrepancy exists between the positive impact of combined AZT and ddl treatment on plasma viral load and CD4 counts and the lack of any effect on the process of lymphocyte apoptosis. We suggest to use the measurement of apoptotic lymphocytes as a surrogate marker to predict, in combination with viral load and CD4 counts, a large proportion of the clinical effect of antiviral therapy.

L-Carnitine, a Modulator of Immunometabolic Homeostasis in Subjects Infected with the Human Immunodeficiency Virus

The inexorable decline in the numbers of CD4 T lymphocytes, which have A a central role in the immune response to pathogens, and their association with the loss of cell-mediated immunity are major hallmarks of advancing acquired immunodeficiency syndrome (AIDS).