Frank J.T. Staal

CD4 and CD8 T cells with high intracellular glutathione levels are selectively lost as the HIV infection progresses

Maintenance of intracellular glutathione (GSH) levels has been implicated in blocking cytokine-stimulated HIV replication in vitro, in both acute and latent infection models. We demonstrate here that subsets of human peripheral blood mononuclear cells differ substantially in mean GSH levels, as measured on a cell-by-cell basis with the fluorescence-activated cell sorter (FACS): B cells have the lowest GSH levels; T cells are intermediate; and monocytes and macrophages have the highest levels. Furthermore, GSH levels subdivide the CD4 and CD8 T cell subsets into two classes each: high- and low-GSH cells, which cannot be distinguished by cell size or by currently known surface markers. Significantly, the high-GSH T cells are selectively depleted early during the HIV infection, and are effectively missing in all ARC and AIDS patients.

N-Acetylcysteine: Potential for AIDS Therapy

The observations that people infected with HIV suffer not only from an inflammatory stress but also from depleted glutathione levels have led to a general hypothesis that these two are causally related, and that treatment of AIDS should include thiol-replenishment therapy. In particular, inflammatory stimulations are dependent on intracellular thiol levels, as they are potentiated at low glutathione levels (oxidative stress) and inhibited at high glutathione levels. Inflammatory stress may itself lead to decreased levels of glutathione. HIV has taken advantage of inflammatory signals to regulate its own replication; thus, the HIV infection is exacerbated by low levels of glutathione. We have shown that N-acetylcysteine can inhibit inflammatory stimulations, including that of HIV replication. Since N-acetylcysteine can replenish depleted glutathione levels in vivo, we suggest that it be used as an adjunct in the treatment of AIDS.

[17] Redox regulation of activation of NF-κB transcription factor complex: Effects of N-acetylcysteine

Publisher Summary This chapter describes detailed methods on the appropriate cell culture conditions to study the influence of oxidants and antioxidants, the preparation of nuclear protein extracts, and the use of gel retardation assays to detect the presence of activated NF- K B in the nucleus. The chapter also describes a reporter gene-based system to assay whether the DNA-bound NF- K B is transcriptionally active. NF- K B is a heterodimeric transcription factor complex composed, in its classic form, of two DNA-binding subunits: p50 and p65. NF- K B was first identified as a DNA-binding activity specific for the KB motif in the immunoglobin kappa ( K ) enhancer. Cloning of the NF- K B p50 and p65 genes revealed a family of NF- K B/rel proteins that participate in a variety of transcriptionally regulated processes, such as lymphocyte differentiation, responsiveness to cytokines, and embryonic development in Drosophila. NF- K B is present in many cell types in an inactive form in the cytoplasm, bound to a cytoplasmic retention molecule called I- K B (for inhibitor of NF- K B). Nuclear translocation of NF- K B is achieved after stimulation of the cells by many different inducers (cytokines, phorbol esters, viral proteins, oxidants) and presumably involves phosphorylation of I- K B which disrupts its interaction with the p65 NF- K B subunit. The NF- K B complex is then free to migrate to the nucleus and transactivate its various target genes.

Cysteine/Glutathione Deficiency: A Significant and Treatable Corollary of Disease

Glutathione (GSH) deficiency may play a pivotal role in a variety of apparently unrelated clinical conditions and diseases. Orally administered N-acetylcysteine (NAC), which replenishes the cysteine required for GSH synthesis, has been tested in a large number of randomized placebo-controlled trials involving these diseases and conditions. This chapter focused on developing a base of evidence suggesting that NAC administration improves disease by increasing cysteine and/or GSH in a variety of diseases, thereby implying a significant role for GSH deficiency in the clinical basis of many diseases. To develop this base of evidence, we systematically selected studies which considered the hypothesis that the therapeutic efficacy for NAC is an indication that cysteine and/or GSH deficiency is a pathophysiological part of the diseases studied. In this manner we focus this chapter on explaining the biological mechanisms of NAC therapy in a wide variety of disorders and demonstrate its ubiquitous role in improving disease that involves disrupted GSH and/or cysteine metabolism. Electronic supplementary material The online version of this article (10.1007/978-981-10-5311-5_20) contains supplementary material, which is available to authorized users.

Pharmacology, Formulations, and Adverse Effects

Besides understanding the effectiveness of N-acetylcysteine (NAC) for the treatment of disease and its effect on physiological systems, other considerations of NAC are important, including the pharmacology, formulations, and adverse effects of NAC. This chapter will review these important aspects of NAC. Few published trials have examined the pharmacokinetics of NAC. Maximum plasma concentration increases with oral NAC doses (up to 1200 mg has been studied), particularly with sustained-release formulations. Oral and intravenous NAC seems to have similar half-lives (around 6 h). The pharmacokinetics of NAC is altered by chronic liver and renal disease as well as exercise. Clearance is altered in the neonatal period and with dialysis. NAC does not appear to alter the concentration of several common antibiotics, including amoxicillin, cefadroxil, cefpodoxime, doxycycline, and erythromycin. There are many nonprescription forms of NAC that are not regulated, particularly in the United States, which can easily oxidize in its dimeric form (“di-NAC”) which can result in opposite physiological effects. There are several formulations that follow Good Manufacturing Practice standards that are believed to be more stable.

Distinct Subpopulations of Human Peripheral Blood Monocytes Characterized by Absence of the CD14 Surface Marker, and Distinguished by High or Low Intracellular Glutathione

The tripeptide glutathione (GSH) is the most prevalent intracellular thiol [1]. Among its many functions, GSH serves as a reducing agent and an antioxidant, absorbing intracellular reactive oxygen intermediates (ROI) which result from physical or chemical insults to cells [1]. ROI are also believed to be the toxic element of tumor cell cytotoxicity produced in response to tumor necrosis factor (TNF) [2–4]. Indeed, increased intracellular GSH protects otherwise sensitive murine fibroblasts from TNF cytotoxicity, in vitro [5], and N-acetytcysteine (NAC), a synthetic precursor of GSH, abrogates TNF cytotoxicity in rats [3].