n-n-diacetylcystine and Arteriosclerosis

Inflammatory processes in the arterial wall are important in atherogenesis. The present review discusses the development of DiNAC as a potential new treatment modality for atherosclerosis related diseases. DiNAC, N,N'-diacetyl-L-cystine, is the disulphide dimer of N-acetyl cysteine, NAC. It was selected as an immunomodulating drug candidate due to its ability to modify contact sensitivity/delayed type hypersensitivity (CS/DTH) reactions in vivo. Initial structure-activity relationship (SAR) studies indicated that an intact disulfide bridge was essential for this effect. Antioxidants, like probucol and some close analogs with two sulphurs in close proximity (but not disulphides), were also found to have similar effects on CS/DTH reactions. These antioxidants have antiatherosclerotic effects, while structurally related compounds without sulphurs do not. Therefore, it was hypothesized that DiNAC might also possess antiatherosclerotic effects. This was investigated in WHHL rabbits and mice. In both species, DiNAC had antiatherosclerotic activity similar to that of probucol. The effect of DiNAC was not due to an alteration of lipid metabolism. Impaired endothelium mediated relaxation is known to be associated with atherosclerosis. DiNAC was shown to reverse this process in WHHL rabbits with advanced atherosclerosis, probably due to an action on the vessel wall itself that is not related to the extent of atherosclerosis or to plasma lipid levels. Preliminary data from a clinical investigation in hypercholesterolemic subjects suggest that DiNAC is likely to have similar effects also in patients. Taken together, these findings suggest immunomodulation to be a potential new therapy for atherosclerosis related diseases. DiNAC may represent a new treatment modality for such diseases.

Topics: Adjuvants, Immunologic; Animals; Antioxidants; Arteriosclerosis; Clinical Trials as Topic; Cystine; Drug Evaluation, Preclinical; Endothelium, Vascular; Humans; Hypersensitivity, Delayed; Quantitative Structure-Activity Relationship; Vasodilation

Not all antioxidants reduce atherosclerosis. This may be because atherosclerosis has an autoimmune, inflammatory pathogenesis. As probucol is both an antioxidant and an immunomodulatory drug, it may be the immunomodulatory effect that underlies its ability to reduce atherosclerosis. N,N-Diacetyl-L-cystine is not an antioxidant but is immunomodulatory. In the Watanabe-heritable hyperlipidaemic rabbit model of familial hypercholesterolaemia, N,N-diacetyl-L-cystine treatment does not lower lipid levels but it does reduce atherosclerosis. Immunomodulation may be a new approach to the treatment of atherosclerosis.

Topics: Adjuvants, Immunologic; Animals; Arteriosclerosis; Benzhydryl Compounds; Cystine; Dermatitis, Contact; Mice; Mice, Inbred BALB C; Phenols; Probucol; Rabbits

In this study, we have applied and evaluated a modified cDNA representational difference analysis (RDA) protocol based on magnetic bead technology to study the molecular effects of a candidate drug (N,N'-diacetyl-L-cystine, DiNAC) in a model for atherosclerosis. Alterations in a gene expression profile induced by DiNAC were investigated in a human monocytic cell line (THP-1) differentiated into macrophage-like cells by lipopolysaccharide and further exposed to DiNAC. Three rounds of subtraction have been performed and the difference products from the second and third rounds have been characterized in detail by analysis of over 1000 gene sequences. Two protocols for analysis of the subtraction products have been evaluated, a shotgun approach and size selection of both distinct fragments and band-patterned smear. We demonstrate that in order to obtain a representative view of the most abundant gene fragments, the shotgun procedure is preferred. The obtained sequences were analyzed against the UniGene and Expressed Gene Anatomy Database (EGAD) databases and the results were visualized and analyzed with the ExProView software enabling rapid pair-wise comparison and identification of individual genes or functional groups of genes with altered expression levels. The identified differentially expressed gene sequences were comprised of both genes with known involvement in atherosclerosis or cholesterol biosynthesis and genes previously not implicated in these processes. The applicability of a solid-phase shotgun RDA protocol, combined with virtual chip monitoring, results in new starting points for characterization of novel candidate drugs.

Topics: Arteriosclerosis; Cell Line; Cystine; DNA, Complementary; Gene Expression Profiling; Gene Expression Regulation; Humans; Nucleic Acid Hybridization; Polymerase Chain Reaction; Reproducibility of Results; Reverse Transcriptase Polymerase Chain Reaction; Software

Oxidation of lipoprotein-derived lipids is generally accepted to be important in atherogenesis, and lipophilic antioxidants have been suggested as potential antiatherosclerotic agents. The antiatherogenic effects observed by certain antioxidants, especially probucol, in different animal models support this suggestion. There are however also cases where other lipophilic antioxidants have not been able to support this hypothesis. This has raised the question whether the effects of probucol and similar compounds are mainly due to some other property, unrelated to their antioxidant efficacy. For example, probucol is shown to possess immunomodulatory properties. Immune reactions are known to occur during atherogenesis. We therefore tested the dimer of N-acetylcysteine, DiNAC, which is a disulfide with immunomodulating properties and enhances oxazolone-induced contact sensitivity (CS) reactions in mice, for effects on atherosclerosis. When given to male heritable hyperlipidemic rabbit (WHHL) rabbits from 10 to 22 weeks of age, this compound reduced by 50% thoracic aorta atherosclerosis (p < 0.05), without affecting plasma lipid levels. Here we also show that probucol and a close chemical analog, both known to prevent atherosclerosis in WHHL rabbits, enhance the CS reaction in mice, while two other related antioxidants did not affect the CS reaction. At least one of these is also without effect on atherosclerosis in WHHL rabbits. The results show that DiNAC might represent a new treatment modality for atherosclerosis-related disease, and suggest that some antioxidants may have antiatherosclerotic properties more related to "immunomodulatory" properties than to antioxidant properties in general.

Topics: Acetylcysteine; Adjuvants, Immunologic; Animals; Antioxidants; Arteriosclerosis; Cholesterol; Cystine; Dermatitis, Contact; Disulfides; Male; Mice; Mice, Inbred BALB C; Oxazolone; Probucol; Rabbits; Receptors, LDL; Structure-Activity Relationship; Triglycerides