Parthanatos-associated proteins are stimulated intraocularly during development of experimental murine cytomegalovirus retinitis in mice with retrovirus-induced immunosuppression.

The mechanisms that contribute to retinal tissue destruction during the onset and progression of AIDS-related human cytomegalovirus (HCMV) retinitis remain unclear. Evidence for the stimulation of multiple cell death pathways including apoptosis, necroptosis, and pyroptosis during the pathogenesis of experimental murine cytomegalovirus (MCMV) retinitis in mice with retrovirus-induced immunosuppression (MAIDS) has been reported. Parthanatos is a caspase-independent cell death pathway mediated by rapid overactivation of poly (ADP-ribose) polymerase-1 (PARP-1) and distinct from other cell death pathways. Using the MAIDS model of MCMV retinitis, studies were performed to test the hypothesis that intraocular MCMV infection of mice with MAIDS stimulates parthanatos-associated messenger RNAs (mRNAs) and proteins within the eye during the development of retinal necrosis that takes place by 10 days after MCMV infection. MCMV-infected eyes of MAIDS mice exhibited significant stimulation of PARP-1 mRNA and proteins at 3 days after infection but declined thereafter at 6 and 10 days after infection. Additional studies showed the intraocular stimulation of mRNAs or proteins before MCMV retinitis development for two additional participants in parthanatos, polymer of ADP-ribose and poly (ADP-ribose) glycohydrolase. These results provide new evidence for a role for parthanatos during MAIDS-related MCMV retinitis that may also extend to AIDS-related HCMV retinitis.

Glutathione Depletion Is Linked with Th2 Polarization in Mice with a Retrovirus-Induced Immunodeficiency Syndrome, Murine AIDS: Role of Proglutathione Molecules as Immunotherapeutics.

UNLABELLED: Injection of the LP-BM5 murine leukemia virus into mice causes murine AIDS, a disease characterized by many dysfunctions of immunocompetent cells. To establish whether the disease is characterized by glutathione imbalance, reduced glutathione (GSH) and cysteine were quantified in different organs. A marked redox imbalance, consisting of GSH and/or cysteine depletion, was found in the lymphoid organs, such as the spleen and lymph nodes. Moreover, a significant decrease in cysteine and GSH levels in the pancreas and brain, respectively, was measured at 5 weeks postinfection. The Th2 immune response was predominant at all times investigated, as revealed by the expression of Th1/Th2 cytokines. Furthermore, investigation of the activation status of peritoneal macrophages showed that the expression of genetic markers of alternative activation, namely, Fizz1, Ym1, and Arginase1, was induced. Conversely, expression of inducible nitric oxide synthase, a marker of classical activation of macrophages, was detected only when Th1 cytokines were expressed at high levels. In vitro studies revealed that during the very early phases of infection, GSH depletion and the downregulation of interleukin-12 (IL-12) p40 mRNA were correlated with the dose of LP-BM5 used to infect the macrophages. Treatment of LP-BM5-infected mice with N-(N-acetyl-l-cysteinyl)-S-acetylcysteamine (I-152), an N-acetyl-cysteine supplier, restored GSH/cysteine levels in the organs, reduced the expression of alternatively activated macrophage markers, and increased the level of gamma interferon production, while it decreased the levels of Th2 cytokines, such as IL-4 and IL-5. Our findings thus establish a link between GSH deficiency and Th1/Th2 disequilibrium in LP-BM5 infection and indicate that I-152 can be used to restore the GSH level and a balanced Th1/Th2 response in infected mice. IMPORTANCE: The first report of an association between Th2 polarization and alteration of the redox state in LP-BM5 infection is presented. Moreover, it provides evidence that LP-BM5 infection causes a decrease in the thiol content of peritoneal macrophages, which can influence IL-12 production. The restoration of GSH levels by GSH-replenishing molecules can represent a new therapeutic avenue to fight this retroviral infection, as it reestablishes the Th1/Th2 balance. Immunotherapy based on the use of pro-GSH molecules would permit LP-BM5 infection and probably all those viral infections characterized by GSH deficiency and a Th1/Th2 imbalance to be more effectively combated.

Murine immunodeficiency virus-induced peripheral neuropathy and the associated cytokine responses.

Distal symmetrical polyneuropathy is the most common form of HIV infection-associated peripheral neuropathy and is often associated with pain. C57BL/6 (B6) mice infected with LP-BM5, a murine retroviral isolate, develop a severe immunodeficiency syndrome similar to that in humans infected with HIV-1, hence the term murine AIDS. We investigated the induction of peripheral neuropathy after LP-BM5 infection in B6 mice. Infected B6 mice, like HIV-infected humans, exhibited behavioral (increased sensitivity to mechanical and heat stimuli) and pathological (transient loss of intraepidermal nerve fibers) signs of peripheral neuropathy. The levels of viral gag RNA were significantly increased in all tissues tested, including spleen, paw skin, lumbar dorsal root ganglia, and lumbar spinal cord, postinfection (p.i.). Correlated with the development of peripheral neuropathy, the tissue levels of several cytokines, including IFN-γ, IL-1ß, IL-6, and IL-12, were significantly elevated p.i. These increases had cytokine-specific and tissue-specific profiles and kinetics. Further, treatment with the antiretroviral agent zidovudine either significantly reduced or completely reversed the aforementioned behavioral, pathologic, and cytokine changes p.i. These data suggest that LP-BM5 infection is a potential mouse model of HIV-associated distal symmetrical polyneuropathy that can be used for investigating the roles of various cytokines in infection-induced neuropathic pain. Further investigation of this model could give a better understanding of, and lead to more effective treatments for, HIV infection-associated painful peripheral neuropathy.

Mice with disrupted type I protein kinase A anchoring in T cells resist retrovirus-induced immunodeficiency.

Type I protein kinase A (PKA) is targeted to the TCR-proximal signaling machinery by the A-kinase anchoring protein ezrin and negatively regulates T cell immune function through activation of the C-terminal Src kinase. RI anchoring disruptor (RIAD) is a high-affinity competitor peptide that specifically displaces type I PKA from A-kinase anchoring proteins. In this study, we disrupted type I PKA anchoring in peripheral T cells by expressing a soluble ezrin fragment with RIAD inserted in place of the endogenous A-kinase binding domain under the lck distal promoter in mice. Peripheral T cells from mice expressing the RIAD fusion protein (RIAD-transgenic mice) displayed augmented basal and TCR-activated signaling, enhanced T cell responsiveness assessed as IL-2 secretion, and reduced sensitivity to PGE(2)- and cAMP-mediated inhibition of T cell function. Hyperactivation of the cAMP-type I PKA pathway is involved in the T cell dysfunction of HIV infection, as well as murine AIDS, a disease model induced by infection of C57BL/6 mice with LP-BM5, a mixture of attenuated murine leukemia viruses. LP-BM5-infected RIAD-transgenic mice resist progression of murine AIDS and have improved viral control. This underscores the cAMP-type I PKA pathway in T cells as a putative target for therapeutic intervention in immunodeficiency diseases.

A novel role for APOBEC3: susceptibility to sexual transmission of murine acquired immunodeficiency virus (mAIDS) is aggravated in APOBEC3 deficient mice.

BACKGROUND: APOBEC3 proteins are host factors that restrict infection by retroviruses like HIV, MMTV, and MLV and are variably expressed in hematopoietic and non-hematopoietic cells, such as macrophages, lymphocytes, dendritic, and epithelia cells. Previously, we showed that APOBEC3 expressed in mammary epithelia cells function to limit milk-borne transmission of the beta-retrovirus, mouse mammary tumor virus. In this present study, we used APOBEC3 knockout mice and their wild type counterpart to query the role of APOBEC3 in sexual transmission of LP-BM5 MLV - the etiological agent of murine AIDs (mAIDs). RESULTS: We show that mouse APOBEC3 is expressed in murine genital tract tissues and gametes and that genital tract tissue of APOBEC3-deficient mice are more susceptible to infection by LP-BM5 virus. APOBEC3 expressed in genital tract tissues most likely plays a role in decreasing virus transmission via the sexual route, since mice deficient in APOBEC3 gene have higher genitalia and seminal plasma virus load and sexually transmit the virus more efficiently to their partners compared to APOBEC3+ mice. Moreover, we show that female mice sexually infected with LP-BM5 virus transmit the virus to their off-spring in APOBEC3-dependent manner. CONCLUSION: Our data indicate that genital tissue intrinsic APOBEC3 restricts genital tract infection and limits sexual transmission of LP-BM5 virus.

Anaplastic plasmacytomas: relationships to normal memory B cells and plasma cell neoplasms of immunodeficient and autoimmune mice.

Anaplastic plasmacytomas (APCTs) from NFS.V(+) congenic mice and pristane-induced plasmacytic PCTs from BALB/c mice were previously shown to be histologically and molecularly distinct subsets of plasma cell neoplasms (PCNs). Here we extended these comparisons, contrasting primary APCTs and PCTs by gene expression profiling in relation to the expression profiles of normal naïve, germinal centre, and memory B cells and plasma cells. We also sequenced immunoglobulin genes from APCT and APCT-derived cell lines and defined surface phenotypes and chromosomal features of the cell lines by flow cytometry and by spectral karyotyping and fluorescence in situ hybridization. The results indicate that APCTs share many features with normal memory cells and the plasma cell-related neoplasms (PLs) of FASL-deficient mice, suggesting that APCTs and PLs are related and that both derive from memory B cells. Published in 2010 by John Wiley & Sons, Ltd.

Inhibition of premature death by isothiocyanates through immune restoration in LP-BM5 leukemia retrovirus-infected C57BL/6 mice.

The purpose of this study was to determine the effect of isothiocyanates (ITCs) in delaying the progression of the murine immunodeficiency virus to murine AIDS, resulting in increased life span. Furthermore, we investigated the role of ITCs in modulating immune dysfunction caused by LP-BM5 retrovirus infection. Among the tested ITCs, oral administration of sulforaphane (SUL), benzyl isothiocyante (BITC), and phenethyl isothiocyanate (PEITC) showed the inhibition of premature death caused by LP-BM5 retrovirus infection, while indolo[3,2-b] carbazole (ICZ) and indole-3-carbinol (I3C) did not delay the progress of the LP-BM5 retrovirus to murine AIDS. Inhibition of premature death by BITC, PEITC, and SUL could be explained by restoration of the immune system and down regulation of free radicals. Dysfunction of T and B cell mitogenesis caused by retrovirus infection in primary cultured splenocytes has been partially recovered with administration of BITC, PEITC, and SUL. There was a shift from imbalanced cytokine production (increased Th2 and decreased Th1 cell cytokine production) into balanced Th1/Th2 cell secretion of cytokines under administration of these ITCs during the development of murine AIDS. Hepatic vitamin E level was significantly restored by administration of these ITCs, in accordance with reduced hepatic lipid peroxidation levels. This study suggests that certain types of ITCs have beneficial effects in preventing premature death during progression to murine AIDS by restoration of immune dysfunction and removal of excessive free radicals, implying that selective usage of ITCs would be helpful in retarding the progression from HIV infection to AIDS.

Citrobacter-induced colitis in mice with murine acquired immunodeficiency syndrome.

Over the period of a year, colitis was observed in 44 mice raised in a conventional nonspecific pathogen-free colony, 41 of these having concomitant retrovirus-induced murine acquired immunodeficiency syndrome (MAIDS). The lesions varied from bacterial colonization to hyperplasia of colonic mucosa to severe, often fatal, ulceration. Citrobacter rodentium was isolated from the colon and/or liver of 2 mice with colitis. When C57BL/6 mice with or without MAIDS were given graded doses of the bacterium, only those with MAIDS developed colitis, and C rodentium was reisolated from their livers. Thus, mice with MAIDS can develop severe disease following opportunistic infection with an environmental contaminant of the colony that is nonpathogenic for normal adult mice.

Myeloid-derived suppressor cells in murine AIDS inhibit B-cell responses in part via soluble mediators including reactive oxygen and nitrogen species, and TGF-ß.

Monocytic myeloid-derived suppressor cells (M-MDSCs) were increased during LP-BM5 retroviral infection, and were capable of suppressing not only T-cell, but also B-cell responses. In addition to previously demonstrating iNOS- and VISTA-dependent M-MDSC mechanisms, in this paper, we detail how M-MDSCs utilized soluble mediators, including the reactive oxygen and nitrogen species superoxide, peroxynitrite, and nitric oxide, and TGF-ß, to suppress B cells in a predominantly contact-independent manner. Suppression was independent of cysteine-depletion and hydrogen peroxide production. When two major mechanisms of suppression (iNOS and VISTA) were eliminated in double knockout mice, M-MDSCs from LP-BM5-infected mice were able to compensate using other, soluble mechanisms in order to maintain suppression of B cells. The IL-10 producing regulatory B-cell compartment was among the targets of M-MDSC-mediated suppression.

Modulation of tumor necrosis factor and gamma interferon production by cocaine and morphine in aging mice infected with LP-BM5, a murine retrovirus.

The actions of retroviral infections, aging, and cocaine and morphine injection on cytokine production were investigated in C57BL/6 female mice. Retroviral infection with LP-BM5 murine leukemia virus was further developed as a model of murine acquired immunodeficiency syndrome (AIDS). The effects of cocaine and morphine on gamma-interferon (IFN) and tumor necrosis factor (TNF) production in vivo and with isolated spleen cells were measured by a sandwich enzyme-linked immunosorbent assay (ELISA) method. Serum IFN was generally not detected in any group except mice injected with saline and young mice infected with LP-BM5 virus. Splenocytes from mice with murine AIDS produced less IFN when stimulated in vitro by ConA. In aged mice, IFN production by spleen cells was severely suppressed by retroviral infection. Cocaine had a tendency to suppress IFN production by stimulated cells in vitro. Morphine tended to reduce IFN production by spleen cells from retrovirally infected animals. The serum TNF level in mice with murine AIDS was elevated creating higher levels in morphine and morphine plus cocaine treated uninfected mice while cocaine injection eliminated serum TNF. When stimulated in vitro by lipopolysaccharides (LPS), splenocytes from mice with murine AIDS also produced more TNF than uninfected controls. TNF production in vitro and in vivo was significantly increased by retroviral infection. Therefore, results indicate that cocaine and retroviral infection modulate TNF and IFN production.

Cyclo-oxygenase type 2-dependent prostaglandin E2 secretion is involved in retrovirus-induced T-cell dysfunction in mice.

MAIDS (murine AIDS) is caused by infection with the murine leukaemia retrovirus RadLV-Rs and is characterized by a severe immunodeficiency and T-cell anergy combined with a lymphoproliferative disease affecting both B- and T-cells. Hyperactivation of the cAMP-protein kinase A pathway is involved in the T-cell dysfunction of MAIDS and HIV by inhibiting T-cell activation through the T-cell receptor. In the present study, we show that MAIDS involves a strong and selective up-regulation of cyclo-oxygenase type 2 in the CD11b+ subpopulation of T- and B-cells of the lymph nodes, leading to increased levels of PGE2 (prostaglandin E2). PGE2 activates the cAMP pathway through G-protein-coupled receptors. Treatment with cyclo-oxygenase type 2 inhibitors reduces the level of PGE2 and thereby reverses the T-cell anergy, restores the T-cell immune function and ameliorates the lymphoproliferative disease.

Localization of quinolinic acid in the murine AIDS model of retrovirus-induced immunodeficiency: implications for neurotoxicity and dendritic cell immunopathogenesis.

OBJECTIVE AND DESIGN: Using murine AIDS (MAIDS) as a model of retrovirus-induced immunodeficiency, the aims of this study were (1) to determine the cellular source(s) of quinolinic acid (Quin) with regard to its significance as a potential neuroexcitotoxin in AIDS dementia complex, and (2) to characterize the relationship between dendritic cell Quin immunoreactivity and the histopathological changes associated with the progression of disease. METHODS: Mice with MAIDS were sacrificed from 1 to 16 weeks post-infection. Temporal and spatial changes in the in vivo distribution of Quin at the cellular level were determined by carbodiimide-based immunohistochemical methods. RESULTS: Cellular Quin immunoreactivity was chronically elevated in lymphoid tissues of mice with MAIDS. In contrast, no cellular Quin immunoreactivity was visible in the brain parenchyma at any timepoint studied. CONCLUSION: These findings are consistent with the view that select immune cells in the peripheral lymphoid tissues may be the primary source of Quin, which may contribute to neurotoxic complications in retrovirus-induced immunodeficiency syndromes. The predominant Quin immunoreactive cell types changed with the progression of disease. A significant finding was the marked increase in the number of Quin immunoreactive dendritic cells in the early phase of MAIDS, suggesting a relationship between dendritic cells and Quin in retroviral infection.

Changes in 1,25-(OH)2D3 synthesis and its receptor expression in spleen cell subpopulations of mice infected with LPBM5 retrovirus.

This study examines the influence of chronic retroviral infection of mice with a LPBM5 virus mixture on the paracrine system involving immune cells and 1,25-(OH)2D3 in the spleen. Plasma ionized calcium, 25-(OH)D and 1,25-(OH)2D of infected mice were unchanged. In contrast, the specific binding of 1,25-(OH)2D3 to spleen cytosol and the number of monocyte/macrophages expressing 1,25-(OH)2D3 receptors (VDR) were markedly increased. The retroviral infection also influenced the local production of 1,25-(OH)2D3 in the spleen. It did not alter this production in monocyte/macrophages but increased that in isolated T cells. Isolated B cells in control mice did not produce 1,25-(OH)2D3, but they increased the ability of isolated T cells to produce this metabolite during coculture incubations. Infection altered this cell interaction as 1,25-(OH)2D3 production in infected T cells decreased when these cells were cocultured with infected B cells. Thus, chronic retroviral infection alters both the local vitamin D metabolism and VDR expression by immune cells in mice. These findings suggest close local interactions between 1,25-(OH)2D3 and immune system activation during retroviral infection.

Pentoxifylline decreases brain levels of platelet activating factor in murine AIDS.

Tumor necrosis factor-alpha (TNF-alpha) and platelet-activating factor (PAF) have been implicated in the pathogenesis of human immunodeficiency virus (HIV)-associated encephalopathy. The effects of pentoxifylline on brain PAF levels were examined in mice infected with the LP-BM5 murine leukemia virus (MuLV). Seven weeks after viral inoculation, significant increases in serum TNF-alpha and brain PAF levels were observed. One week of treatment with pentoxifylline initiated 6 weeks postinfection significantly reduced both serum TNF-alpha and brain PAF levels. A significant positive correlation was observed between the levels of these substances (r = 0.62; P < 0.01). This study demonstrates that pentoxifylline treatment was effective in decreasing the levels of TNF-alpha in the serum and PAF levels in the brain of mice infected with the LP-BM5 MuLV.

Absence of involvement of nitric oxide in LP-BM5-induced immunodeficiency syndrome.

To examine the role of nitric oxide (NO) in murine AIDS (MAIDS) pathogenesis, we determined NO production and inducible NOS (iNOS) mRNA expression in the macrophages of LP-BM5-infected mice, together with the in vivo effects of L-NAME, a competitive inhibitor of NO synthase. LP-BM5 infection induced neither spontaneous nitrite production nor iNOS mRNA expression. No differences in IFN gamma + LPS-induced nitrite production or iNOS mRNA expression were observed in macrophages, from non-infected or infected mice. Spleen weight, ecotropic MuLV replication, the blood lymphocyte phenotype and proliferative response of splenocytes were not modified by L-NAME. LP-BM5 infection did not increase macrophage NO production and NO production did not appear to protect against LP-BM5-induced immunodeficiency.

Dilated cardiomyopathy in retrovirally infected mice: a novel model for silent viral DCM?

Dilated cardiomyopathy (DCM) is a clinically relevant disease that can occur independently or secondary to other diseases such as HIV infection and AIDS. To study this latter process, we used a model in which mice are infected with the LP-BM5 murine AIDS (MAIDS) retrovirus. Cardiac function of control and infected mice was determined through the in vivo analysis of left ventricular pressure-volume loops. Furthermore, the role of myocarditis was investigated through immunohistochemistry for T-cell, B-cell, and macrophage cardiac infiltrates and Northern blot analysis for tumor necrosis factor (TNF)-alpha and inducible nitric oxide synthase (iNOS). End-systolic and end-diastolic volumes were significantly increased and ventricular stiffness was significantly decreased in infected mice, consistent with DCM; however, no staining for inflammatory cellular infiltrates or TNF-alpha and iNOS was seen. These data support the conclusion that the LP-BM5 HIV model virus causes DCM in the absence of chronic cardiac inflammation. These findings support MAIDS retroviral infection as a new model of idiopathic DCM in which myo-carditis does not occur.

Changes in hepatic lipid composition after infection by LP-BM5 murine leukemia virus causing murine AIDS.

The severe hepatic disorders in patients with acquired immune deficiency syndrome (AIDS) is often attributed to a variety of other factors which could affect hepatic function. To evaluate the mechanism of liver damage in murine AIDS-induced immune-suppressed animal, a murine model of AIDS (MAIDS), caused by infection with LP-BM5 murine leukemia virus was used at a late stage of the disease. Retroviral infection significantly increased hepatic cholesterol, triacylgycerol and the cholesterol/phospholipid ratio. Similarly, the proportions of palmitic, palmitoleic, linoleic, ratios of linoleic to arachidonic and saturated to unsaturated fatty acids were significantly lower while the proportion of oleic, docosatetraenoic and docosahexenoic fatty acids were significantly increased in the retrovirus infected mice. Hepatic dysfunction as evidence by increased serum transaminase levels were also observed in the retrovirus infected animals. The data suggest that the liver damage in murine AIDS is induced by retroviral infection and the desaturase enzymes system necessary to maintain regular balance of the fatty acids in the cells may be affected during retroviral infection.

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.

Murine cytomegalovirus retinitis during MAIDS: Susceptibility correlates with elevated intraocular levels of interleukin-4 mRNA.

PURPOSE: To determine if murine cytomegalovirus (MCMV)-infected eyes of mice with murine acquired immunodeficiency syndrome (MAIDS) that are destined to develop MCMV retinitis display elevated intraocular levels of interleukin-4 (IL-4) mRNA when compared with uninfected eyes of mice with MAIDS and unmanipulated, uninfected, eyes of normal healthy mice. METHODS: Groups of C57BL/6 mice with MAIDS and normal C57BL/6 mice were infected uniocularly with MCMV by subretinal MCMV injection. IL-4 levels in individual spleens collected five days later from groups of MAIDS mice and normal mice were assessed by quantitative ELISA. MCMV-infected eyes and uninfected contralateral eyes from another group of mice with MAIDS were also collected at five days postinfection and individually subjected to competitive RT-PCR assay and real-time RT-PCR assay for detection and quantification of IL-4 mRNA. Unmanipulated eyes from normal C57BL/6 mice served as controls. RESULTS: IL-4 mRNA was detected at a level of 9.7 +/- 3.4 pg mRNA per 1000 ng total RNA in 100% of MCMV-infected eyes of mice with MAIDS by competitive RT-PCR assay, but could not be detected in any of the uninfected eyes of MAIDS mice. In comparison, the more sensitive technique of real-time RT-PCR assay detected copies of IL-4 cDNA in both MCMV-infected eyes and uninfected eyes of MAIDS mice. MCMV-infected eyes showed a 16-fold increase in the number of IL-4 cDNA copies when compared with uninfected eyes. Neither technique detected IL-4 mRNA in unmanipulated eyes of normal mice. As expected, spleen cells from mice with MAIDS expressed significantly greater levels of IL-4 when compared with spleen cells from normal mice. CONCLUSIONS: MCMV-infected mice with MAIDS exhibited an expected preferential activation of Th2 cells as determined by increased levels of IL-4 in spleen cells when compared with spleen cells of normal mice. MCMV-infected eyes destined to develop retinitis during MAIDS also showed increased levels of detectable IL-4 mRNA when compared with uninfected eyes of mice with MAIDS. It is therefore possible that IL-4 synthesis by Th2 CD4+ T cells during retrovirus-induced immunosuppression serves to inhibit the perforin cytotoxic pathway that subsequently allows susceptibility to MCMV retinitis during MAIDS.

Chronic ethanol consumption prior to retrovirus infection alters cytokine production by thymocytes during murine AIDS.

Chronic ethanol (EtOH) consumption may be a cofactor in the development of acquired immune deficiency syndrome (AIDS). As the thymus is an unique site for T cell maturation, we investigated whether thymocytes from EtOH consuming mice were more predisposed to aberrant cytokine production due to retrovirus infection. Adult female C57BL/6 mice were fed 4.5% (v/v) in liquid diet or control liquid diet without EtOH for 10 weeks. All diets contained nutrients at only the recommended daily intake level for mice. Then all mice were infected LP-BM5 retrovirus and were fed control liquid diets without EtOH. The body and thymus weights were not affected by EtOH consumption. However, thymocyte number and proliferation, which had been reduced during murine AIDS, were significantly further reduced by EtOH use. The production of IL-2 and IL-6 by thymocytes, which was lessened during retrovirus infection, were significantly further suppressed by dietary EtOH at 6 weeks postinfection, whereas levels of IL-4 and IFN-gamma by thymocytes, which were elevated during retrovirus infection, were significantly and slightly further increased by EtOH-treated mice prior to retrovirus infection, respectively. These data suggest that dietary EtOH consumption can modulate cytokine production by thymocytes, adversely affecting T cell differentiation, especially during retrovirus infection. These results provide additional evidence that EtOH consumption should be a cofactor during development of AIDS via producing altered cytokine production and then disrupting T cell differentiation.