Resistance to intestinal parasites during murine AIDS: role of alcohol and nutrition in immune dysfunction

Phylogeny-directed search for murine leukemia virus-like retroviruses in vertebrate genomes and in patients suffering from myalgic encephalomyelitis/chronic fatigue syndrome and prostate cancer

Gammaretrovirus-like sequences occur in most vertebrate genomes. Murine Leukemia Virus (MLV) like retroviruses (MLLVs) are a subset, which may be pathogenic and spread cross-species. Retroviruses highly similar to MLLVs (xenotropic murine retrovirus related virus (XMRV) and Human Mouse retrovirus-like RetroViruses (HMRVs)) reported from patients suffering from prostate cancer (PC) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) raise the possibility that also humans have been infected. Structurally intact, potentially infectious MLLVs occur in the genomes of some mammals, especially mouse. Mouse MLLVs contain three major groups. One, MERV G3, contained MLVs and XMRV/HMRV. Its presence in mouse DNA, and the abundance of xenotropic MLVs in biologicals, is a source of false positivity. Theoretically, XMRV/HMRV could be one of several MLLV transspecies infections. MLLV pathobiology and diversity indicate optimal strategies for investigating XMRV/HMRV in humans and raise ethical concerns. The alternatives that XMRV/HMRV may give a hard-to-detect “stealth” infection, or that XMRV/HMRV never reached humans, have to be considered.

Drugs of abuse, immune modulation, and AIDS

Illicit drugs such as amphetamines, cocaine, marijuana, and opiates alter immune function and decrease host resistance to microbes in vitro and in experimental animal models. Effects on the immune system may be mediated indirectly as a result of drug interactions in the central nervous system (CNS) or directly through activation of cognate receptors on various immune cell types. For marijuana and opioids, seven-transmembranal G protein-coupled receptors have been identified in the CNS and in the immune system that may play a functionally relevant role in immune modulation. There is accumulating evidence that sigma(1) receptors play a comparable role in cocaine-mediated alteration of immune responses. A mode by which these exogenously introduced substances affects immunity and host resistance may be by perturbing the balance of Th(1) proinflammatory versus Th(2) anti-inflammatory cytokines and lipid bioeffectors. However, while illicit drugs have been documented to alter immune functions in vitro and in animal models, there is a paucity of controlled longitudinal epidemiological studies that definitively correlate immunosuppressive effects with increased incidence of infections or immune disorders in humans, including infection with the human immunodeficiency virus (HIV) or disease progression to AIDS.

Effect of chronic ethanol feeding on 24-hour rhythms of mitogenic responses and lymphocyte subset populations in thymus and spleen of peripubertal male rats

This work analyzes the effect of chronic ethanol feeding on the 24-hour variation of mitogenic responses and lymphocyte subset populations in thymus and spleen. Animals were maintained under a 12:12-hour light/dark photoperiod and they received a liquid diet for 4 weeks, starting on day 35 of life. The ethanol-fed group received a similar diet to controls except that maltose was isocalorically replaced by ethanol. Ethanol replacement provided 36% of the total caloric content of the diet. Rats were killed at 6 time intervals around the clock, beginning at Zeitgeber time (ZT) 1 (ZT 0 = lights on). Under ethanol intake the splenic and thymic weight decreased. In addition, mean values of the thymic, but not of the splenic T cell number decreased, and mean values of the thymic and splenic CD8+ and CD4+CD8+ number increased. Consequently, the thymic T/B ratio and the thymic and splenic CD4+/CD8+ ratio decreased in ethanol-fed rats. At the same time there was a significant increase in the response of the thymic cells to LPS. The ethanol diet modified the 24-hour rhythmicity of thymic and splenic T, B and CD4+CD8+ cells, thymic CD4+ and splenic CD8+ cells, thymic and splenic T/B and CD4+/CD8+ ratios, as well as of mitogenic responses in both tissues. Chronic ethanol administration presumably affects the endogenous clock that modulates the circadian variation of immune responsiveness in growing rats.