Nitroblue tetrazolium (NBT) reduction by neutrophilic granulocytes in patients with HTLV-III infection

Neutrophil function and glutathione-peroxidase (GSH-px) activity in healthy individuals after treatment with N-acetyl-L-cysteine

The objective of this study was to evaluate the effect of N-acetyl-L-cysteine (NAC) on neutrophilic functions and as an antioxidant. NAC, 600 mg daily, given orally to healthy individuals for a period of 2 weeks, affected some functions of human neutrophilic granulocytes when tested in vitro. NAC treatment caused a decrease in the production of superoxide anions by stimulated neutrophils and the improvement of their phagocytic capacity although it did not affect their random or chemotactic migration. The level of glutathione peroxidase (GSH-px) in thrombocytes of the NAC-treated individuals was increased in comparison with the activity before treatment. These results suggest that NAC might act as a scavenger of oxygen-derived free radicals released by stimulated neutrophils and thereby protect the tissue against the radical caused injury as well as optimize phagocytosis.

N-acetylcysteine treatment and the risk of toxic reactions to trimethoprim-sulphamethoxazole in primary Pneumocystis carinii prophylaxis in HIV-infected patients

In a randomized double blind placebo controlled trial, HIV sero-positive patients with CD4+ cell count less than 200 x 10(6)/l or an AIDS diagnosis were evaluated for drug reactions to trimethoprim-sulphamethoxazole (TMP-SMX) during treatment, including pretreatment, with N-acetylcysteine (NAC) 800 mg daily or placebo. TMP-SMX (one double-strength tablet containing 160 mg of trimethoprim and 800 mg of sulphamethoxazole) was given three times weekly as primary Pneumocystis carinii (PCP) prophylaxis. Thirty percent (n = 15) of the patients experienced adverse reactions 8-20 (mean 12.7) days after starting with TMP-SMX. At entry, low cysteine and glutathione levels in plasma were found in the HIV-positive patients. Age, sex, CD4+ count, plasma cysteine and glutathione levels were not risk factors for adverse reactions to TMP-SMX. However, concomitant therapy with nucleoside analogues was associated with increased risk for TMP-SMX reactions. Oral NAC 800 mg daily was well tolerated, but replenished neither cysteine nor glutathione levels in plasma. NAC 800 mg/day did not significantly decrease the risk of adverse reactions to TMP-SMX in this study, and could thus not be recommended for this purpose. A prolonged pretreatment period and/or higher dose of NAC may be necessary for clinical effect.

Liver endogenous antioxidant defenses in mice fed AIN-76A diet and infected with murine AIDS

The effects of murine AIDS infection on endogenous antioxidant defenses in mice fed the AIN-76A liquid diet were investigated. C57BL/6 female mice were divided into 2 groups: one group was injected interperitoneally with LP-BM5 murine retrovirus (MAIDS) stock, and the other group served as the non-infected control. Two weeks after the infection, the mice were killed and livers were excised for biochemical analysis of the antioxidant defenses. Liver reduced glutathione (GSH) levels and activities of both cytosolic superoxide dismutase (SOD) and mitochondrial SOD were significantly depressed by MAIDS infection. Activities of glutathione reductase (GR) selenium (Se)-dependent glutathione peroxidase (GPx), catalase and glutathione-S-transferase (GST) toward 1-chloro-2,4-dinitrobenzene (CDNB) were not affected by MAIDS infection. A previous study by this laboratory using the Lieber-DeCarli (L-D) all purpose liquid diet caused a decline in total SOD activity and GPx activity, but not GSH levels. The results suggest that MAIDS infection depresses liver antioxidant defenses; however, MAIDS infection of mice fed the AID-76A liquid diet depresses different liver antioxidant defense parameters when compared to those of the mice fed the L-D all purpose liquid diet.

Antioxidant status and lipid peroxidation in patients infected with HIV

Deficiency in antioxidant micronutrients have been observed in patients with AIDS. These observations concerning only some isolated nutrients demonstrate a defect in zinc, selenium, and glutathione. An increase in free radical production and lipid peroxidation has been also found in these patients, and takes a great importance with recent papers presenting an immunodeficiency and more important an increase in HIV-1 replication secondary to free radicals overproduction. We have assessed different studies, trying to obtain a global view of the antioxidant status of these patients. In adults we observe a progressive decrease for zinc, selenium, and vitamin E with the severity of disease, except that selenium remains normal at stage II. However, the main dramatic decrease concerns carotenoids whose level at stage II is only half the normal value. To understand if these decreases in antioxidant and increases in oxidative stress occur secondary to the aggravation of the disease or, conversely, are responsible for it, we undertook a longitudinal survey of asymptotic patients. The preliminary results of this evaluation are presented. Paradoxically, lipid peroxidation is higher at stage II than at stage IV. This may be consecutive to a more intense overproduction of oxygen free radicals by more viable polymorphonuclear (PMN) at the asymptomatic stage. The free radicals production and lipid peroxidation seem secondary to a direct induction by the virus of PMN stimulation and cytokines secretion. N-Acetyl cysteine or ascorbate have been demonstrated in cell culture to be capable of blocking the expression of HIV-1 after oxidative stress and N-acetyl cysteine inhibits in vitro TNF-induced apoptosis of infected cells. In regard to all these experimental data, few serious and large trials of antioxidants have been conducted in HIV-infected patients, although some preliminary studies using zinc or selenium have been performed. In our opinion it is now time to evaluate in humans the beneficial effect of antioxidants. The more promising candidates for presenting synergistic effects when associated with N-acetyl cysteine seem to be beta-carotene, selenium and zinc.

Imbalance between oxidants and antioxidants in the lungs of HIV-seropositive individuals

Following the initial infection with HIV, there is evidence of immune dysfunction despite an apparent normal clinical state. In the context that the lung is a major site affected by opportunistic infection, and that some components of the immune system are activated during early HIV infection, we hypothesized that there may be activation of alveolar macrophages (AM), a key component of the pulmonary host defense system. Compared to cells from normal individuals, AM of asymptomatic HIV-seropositive (HIV+) individuals (CDC-stage II) spontaneously released significantly more superoxide anion (O2-.) (P < 0.002). The O2-. release by AM of HIV-infected individuals was comparable to the spontaneous O2-.-release by AM of cigarette smokers (P > 0.6), a condition often associated with chronic damage of respiratory tissues. The destructive effects of oxidants are normally suppressed by antioxidant defense systems. Evaluation of the concentrations of glutathione, a major component of the pulmonary antioxidant protective screen, demonstrated that the HIV+ state is also characterized by a significant glutathione deficiency in lung epithelial lining fluid (P < 0.001) and in venous plasma (P < 0.001). This suggests that the alveolar structures of HIV+ individuals are continuously exposed to increased amounts of toxic oxygen radicals without adequate protection, i.e. the reactive oxygen metabolites may cause sufficient tissue damage culminating in interstitial lung disease. Further, since many immune functions are susceptible to injury by extracellular oxidants, the consequences of an unsuppressed oxidant burden in the lung may amplify the extent of local immunocompromise. In addition, since glutathione plays an important role in modulating lymphocyte activation and effector functions independent of its antioxidant activity, the systemic glutathione deficiency may contribute to the progressive global immune dysfunction that characterizes HIV infection.

Oxygen radical release by neutrophils of HIV-infected patients

Neutrophils from asymptomatic HIV-infected patients have an increased Nitroblue tetrazolium (NBT) reduction, that is an increased production of oxygen radicals. Plasma from these patients can activate normal neutrophils to an increased NBT-reduction and the neutrophil activating factor thus seems to be mainly plasma bound. Further, the patients also have increased levels of plasma malondialdehyde and thus an increased lipid peroxidation. Plasma cysteine levels are low, a sign of increased consumption of antioxidants. Treatment of the asymptomatic HIV-infected patients with N-acetylcysteine corrected the plasma cysteine levels and had some beneficial effects, but did not inhibit the increased radical production by the neutrophils.

Correction of glutathione deficiency in the lower respiratory tract of HIV seropositive individuals by glutathione aerosol treatment

BACKGROUND

Concentrations of glutathione, a ubiquitous tripeptide with immune enhancing and antioxidant properties, are decreased in the blood and lung epithelial lining fluid of human immunodeficiency virus (HIV) seropositive individuals. Since the lung is the most common site of infection in those who progress to AIDS it is rational to consider whether it is possible to safely augment glutathione levels in the epithelial lining fluid of HIV seropositive individuals, thus potentially improving local host defence.

METHODS

Purified reduced glutathione was delivered by aerosol to HIV seropositive individuals (n = 14) and the glutathione levels in lung epithelial lining fluid were compared before and at one, two, and three hours after aerosol administration.

RESULTS

Before treatment total glutathione concentrations in the epithelial lining fluid were approximately 60% of controls. After three days of twice daily doses each of 600 mg reduced glutathione, total glutathione levels in the epithelial lining fluid increased and remained in the normal range for at least three hours after treatment. Strikingly, even though > 95% of the glutathione in the aerosol was in its reduced form, the percentage of oxidised glutathione in epithelial lining fluid increased from 5% before treatment to about 40% three hours after treatment, probably reflecting the use of glutathione as an antioxidant in vivo. No adverse effects were observed.

CONCLUSIONS

It is feasible and safe to use aerosolised reduced glutathione to augment the deficient glutathione levels of the lower respiratory tract of HIV seropositive individuals. It is rational to evaluate further the efficacy of this tripeptide in improving host defence in HIV seropositive individuals.

Modification of lymphocyte and monocyte functional activity by polymorphonuclear neutrophils in HIV infection

The aim of this study was to determine whether polymorphonuclear neutrophils (PMN) can modify the immune response in HIV cases. Supernatants of PMN (PMNS) from 33 HIV-infected patients (16 with lymphoadenopathy syndrome, 17 with AIDS-related complex) were tested for their influence on the functional activity of lymphocytes and monocytes from 6 healthy donors. PMNS from another 6 healthy donors comprised a control group. It was found that PMNS from HIV-infected patients, but not from healthy donors, induced suppression of lymphocyte proliferative response and down-regulation of CD8 receptor expression on lymphocytes. Decrease of NK-cell cytotoxicity in the presence of PMNS from HIV-infected patients was the same as that from healthy donors. PMNS did not influence the production of anti-HIV antibody by lymphocytes from HIV-infected patients, as well as non-specific IgG by lymphocytes from healthy donors. PMNS effect on functional activity of lymphocytes was blocked completely after treatment of PMN by catalase and superoxide dismutase. At the same time PMNS from HIV-infected patients but not from healthy donors induced increased production of TNF-alpha by monocytes and up-regulation of monocyte phagocytosis. These effects were independent of catalase and superoxide dismutase and were not abrogated by antibody against IL-1, IL-8, TNF-alpha, IFN-gamma or IFN-alpha.

Multicenter, randomized, placebo-controlled study of ditiocarb (Imuthiol) in human immunodeficiency virus-infected asymptomatic and minimally symptomatic patients. The HIV87 Study Group

Ditiocarb sodium has been reported to reduce the progression of human immunodeficiency virus (HIV) infection. To confirm this therapeutic activity and to evaluate the effect of ditiocarb sodium in the early stages of HIV infection, we conducted a randomized, double-blind, placebo-controlled trial in asymptomatic or minimally symptomatic adults with HIV infection. Patients were followed during a 24 mo period, with a clinical and laboratory evaluation every 4 mo. Of 1333 patients who continued therapy after day 1, 669 were randomized to ditiocarb and 664 to placebo. The two treatment groups were comparable at entry, except for the CD4+ cell count, which was lower in the ditiocarb (median 416/mm3) than in the placebo group (median 458/mm3). Acquired immunodeficiency syndrome (AIDS) developed in 106 patients in the ditiocarb group as compared with 68 in the placebo group; 285 patients progressed to AIDS-related complex (157 ditiocarb, 128 placebo); 55 patients died (34 ditiocarb; 21 placebo). The risk of progression to AIDS, after adjustment for baseline CD4+ cell count, was significantly higher in the ditiocarb than in the placebo group (adjusted relative risk = 1.41; p = 0.027). A decrease in CD4+ cell counts was observed, with no significant difference between the ditiocarb and the placebo group. A positive effect of ditiocarb given in the condition of this study can be excluded. Although previous studies have shown opposite results, this study suggests that the use of ditiocarb in HIV-infected patients should be discontinued.

Reactive oxygen intermediates and human immunodeficiency virus (HIV) infection

HIV infection affects various parts of the immune system, including the CD4+ lymphocytes and mononuclear phagocytes, and causes a progressive immunodeficiency. This renders the patient susceptible to various opportunistic infections and neoplasms. Reactive oxygen intermediates (ROI) are important for the intracellular killing of microorganisms by mononuclear phagocytes and neutrophils. Although data are discrepant, several studies suggest that the generation of ROI is impaired in mononuclear phagocytes, and possibly also in neutrophils, from HIV-infected individuals. This may lead to deficient killing of intracellular microorganisms predisposing the HIV-infected patient to certain opportunistic infections. Recently, in vitro studies have shown that ROI activate the intracellular transcription factor nuclear factor kappa B (NF-kappa B) which stimulates HIV replication. Intracellular antioxidant systems, such as the glutathione system, seem to be of importance for the regulation of ROI levels and thus probably for HIV replication in vitro. However, the role of ROI in regulation of HIV replication in vivo is unknown at present. The role of ROI in HIV infection is thus difficult to assess, both at the cellular and clinical level. Reduced intracellular concentrations of ROI may lead to impaired phagocyte microbicidal functions, thus predisposing HIV-infected patients to various opportunistic infections. On the other hand, increased ROI levels may be associated with a stimulation of HIV replication leading to clinical deterioration.

Mononuclear cells from HIV-infected patients produce factors which enhance functional activity of polymorphonuclear neutrophils from healthy subjects

The influence of mononuclear cell supernatants (MNCS) from nine healthy donors and 35 HIV-infected patients (17 with lymphoadenopathy syndrome (LAS), 15 with ARC and three with AIDS) on functional activity of polymorphonuclear neutrophils (PMN) from healthy donors was investigated. MNC after short-term cultivation (24 h) produced factors which enhanced chemiluminescence (CL) and chemotaxis of PMN. This augmentation did not depend on stimulation of MNC by mitogens (lipopolysaccharide Escherichia coli (LPS) and concanavalin A (Con A)) or on activation of PMN by FMLP. After 48 h of cultivation only MNC stimulated by LPS produced these factors. MNCS from HIV-infected patients provoked a more pronounced augmentation of PMN CL compared with MNCS from healthy subjects. This enhancement was observed in patients at all stages of infection, but was more pronounced in patients with LAS. MNCS impact on PMN CL was not connected with proliferative activity of MNC but was correlated with the level of CD4 cells. It was shown that removal of adherent cells from MNC fraction resulted in decreased MNCS impact. Treatment of MNCS by antibody to IL-1 beta, IL-8, interferon-alpha (IFN-alpha) and tumour necrosis factor-alpha (TNF-alpha) did not decrease MNCS impact on PMN CL.

HIV-induced cysteine deficiency and T-cell dysfunction--a rationale for treatment with N-acetylcysteine

Markedly decreased plasma cystine and cysteine concentrations have been found in HIV-infected patients at all stages of the disease and in SIV-infected rhesus macaques. The elevated glutamate levels found in the same patients aggravate the cysteine deficiency by inhibiting the membrane transport activity for cystine. The intact immune system appears to require a delicate balance between pro-oxidant and antioxidant conditions, maintained by a limited and well-regulated supply of cysteine. This balance is obviously disturbed in HIV infection and may contribute to the pathogenesis of AIDS.

Role of polymorphonuclear leukocytes in infection by retroviruses with emphasis on the human immunodeficiency virus

Neutrophil function is an integral part of the host defense against multiple pathogens. Through phagocytosis and production of toxic substances, these short lived cells aid in the effective elimination of invading microorganisms such as bacterial and fungal targets. Viral infections, and in particular those of the retroviral type, appear to suppress the immune response through direct cytotoxic destruction of immune cells or alteration of the biochemical interactions that are essential for eradicating the foreign agent. In this report, we describe abnormalities of neutrophil number and function consequent to HIV and other retroviral infections. A myriad of mechanisms, either alone or in concert may explain the underlying aberrations.

Increased production of malondialdehyde in patients with HIV infection

The mean plasma content of malondialdehyde (MDA) in 30 patients in different stages of HIV infection was found to be about 30% higher than that in controls. The phenomenon was not correlated to the degree of immunodeficiency and was noted early in the course of the disease. This indicates a higher degree of basal lipid peroxidation, which might contribute to the tissue damage seen in these patients. A new reverse phase liquid chromatography method was used for quantitative measurements of MDA in plasma after reaction of this compound with thiobarbituric acid.