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.

Evidence for multiple cell death pathways during development of experimental cytomegalovirus retinitis in mice with retrovirus-induced immunosuppression: apoptosis, necroptosis, and pyroptosis.

AIDS-related human cytomegalovirus (HCMV) retinitis remains a major ophthalmologic problem worldwide. Although this sight-threatening disease is well characterized clinically, many pathogenic issues remain unresolved, among them a basic understanding of the relative roles of cell death pathways during development of retinal tissue destruction. Using an established model of experimental murine cytomegalovirus (MCMV) retinitis in mice with retrovirus-induced immunosuppression (MAIDS), we initially investigated MCMV-infected eyes for evidence of apoptosis-associated molecules in mice with MAIDS of 4 weeks' (MAIDS-4) and 10 weeks' (MAIDS-10) duration, which were resistant and susceptible to retinal disease, respectively, but which harbored equivalent amounts of infectious MCMV. Whereas MCMV-infected eyes of MAIDS-4 mice showed little evidence of apoptosis-associated molecules, MCMV-infected eyes of MAIDS-10 mice showed significant amounts of tumor necrosis factor alpha (TNF-α), TNF receptors 1 and 2, active caspase 8, active caspase 3, TNF-related apoptosis-inducing ligand (TRAIL), TRAIL-R(DR5), Fas, and Fas ligand mRNAs and/or proteins, all detected at peak amounts prior to development of most severe retinal disease. Immunohistochemical staining showed macrophages, granulocytes (neutrophils), Müller cells, and microglial cells as TNF-α sources. Remarkably, quantification of apoptosis by terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling (TUNEL) assay suggested that apoptosis contributed minimally to retinal disease in MCMV-infected eyes of MAIDS-10 mice. Subsequent studies demonstrated that MCMV-infected eyes of MAIDS-10 mice, but not MAIDS-4 mice, showed evidence of significant increases in molecules associated with two additional cell death pathways, necroptosis (receptor-interacting protein 1 [RIP1] and RIP3 mRNAs) and pyroptosis (caspase 1, interleukin 1ß [IL-1ß], and IL-18 mRNAs). We conclude that apoptosis, necroptosis, and pyroptosis participate simultaneously during MAIDS-related MCMV retinitis, and all may play a role during AIDS-related HCMV retinitis.

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.

Role of IP-10/CXCL10 in the progression of pancreatitis-like injury in mice after murine retroviral infection.

Exocrinopathy and pancreatitis-like injury were developed in C57BL/6 (B6) mice infected with LP-BM5 murine leukemia virus, which is known to induce murine acquired immunodeficiency syndrome (MAIDS). The role of chemokines, especially CXCL10/interferon (IFN)-gamma-inducible protein 10 (IP-10), a chemokine to attract CXCR3+ T helper 1-type CD4+ T cells, has not been investigated thoroughly in the pathogenesis of pancreatitis. B6 mice were inoculated intraperitoneally with LP-BM5 and then injected every week with either an antibody against IP-10 or a control antibody. Eight weeks after infection, we analyzed the effect of IP-10 neutralization. Anti-IP-10 antibody treatment did not change the generalized lymphadenopathy and hepatosplenomegaly of mice with MAIDS. The treatment significantly reduced the number of IP-10- and CXCR3-positive cells in the mesenteric lymph nodes (mLNs) but not the phenotypes and gross numbers of cells. In contrast, IP-10 neutralization reduced the number of mononuclear cells infiltrating into the pancreas. Anti-IP-10 antibody treatment did not change the numbers of IFN-gamma+ and IL10+ cells in the mLN but significantly reduced their numbers, especially IFN-gamma+ and IL-10+ CD4+ T cells and IFN-gamma+ Mac-1+ cells, in the pancreas. IP-10 neutralization ameliorated the pancreatic lesions of mice with MAIDS probably by blocking the cellular infiltration of CD4+ T cells and IFN-gamma+ Mac-1+ cells into the pancreas at least at 8 wk after infection, suggesting that IP-10 and these cells might play a key role in the development of chronic autoimmune pancreatitis.

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.

Interleukin-2 immunotherapy and AIDS-related cytomegalovirus retinitis.

Cytokines are small proteins produced by T lymphocytes that mediate immune responses. Those produced by the CD4+ Th1 subset induce cell-mediated immunity, whereas those produced by the CD4+ Th2 subset are more efficient at stimulating immunoglobulin production. The goal of cytokine immunotherapy is prevention or reduction of disease progression through stimulation of cell-mediated immunity (i.e., immune reconstitution) by administration of an exogenous Th1 cytokine such as interleukin-2 (IL-2). Cytokine immunotherapy has its origins in cancer immunobiology where IL-2 has been used successfully to manage several human cancers (metastatic melanoma, acute myelogenous leukemia, and metastatic renal cell carcinoma). More recent work has demonstrated cytokine immunotherapy to be effective at improving immune responses in patients with HIV-1 disease. To explore cytokine immunotherapy for sight-threatening AIDS-related human cytomegalovirus (HCMV) retinitis, we developed a mouse model of experimental murine cytomegalovirus (MCMV) retinitis that employs mice with MAIDS, a retrovirus-induced immunodeficiency syndrome. Systemic cytokine immunotherapy with IL-2, but not with interleukin-12 (IL-12), provides absolute protection against MAIDS-related MCMV retinitis by stimulation of the perforin-mediated pathway of cytotoxicity used by natural killer cells and cytotoxic CD8+ T cells to kill virus-infected cells. Our findings warrant additional studies on the use of cytokine immunotherapy for management of HCMV retinitis (and possibly other opportunistic infections) during HIV-1-induced immunodeficiency. We envision systemic cytokine immunotherapy as an altemative or adjunct to traditional antiviral chemotherapy for optimal management of AIDS-related HCMV retinitis.

Susceptibility to murine cytomegalovirus retinitis during progression of MAIDS: correlation with intraocular levels of tumor necrosis factor-alpha and interferon-gamma.

PURPOSE: To correlate tumor necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) synthesis with histopathologic disease and virus replication within murine cytomegalovirus (MCMV)-infected eyes during progression of murine acquired immunodeficiency syndrome (MAIDS). MATERIALS AND METHODS: Groups of normal mice and mice with MAIDS of 2-weeks (MAIDS-2), 4-weeks (MAIDS-4), and 12-weeks (MAIDS-12) duration were infected uniocularly with MCMV by subretinal MCMV injection. MCMV-inoculated eyes from all mice were subjected to histopathologic analysis, quantitative plaque assay, or cytometric bead array analysis for quantification of TNF-alpha and IFN-gamma. RESULTS: Whereas MCMV-inoculated eyes of normal, MAIDS-2, and MAIDS-4 mice were resistant to MCMV retinitis, all MCMV-inoculated eyes of MAIDS-12 mice developed retinitis. Surprisingly, MCMV-inoculated eyes of MAIDS-4 mice without retinitis harbored high amounts of infectious virus at a level equivalent to that of MCMV-inoculated eyes of MAIDS-12 mice that developed retinitis. Intraocular TNF-alpha levels were consistently approximately 50% greater in MCMV-inoculated eyes of MAIDS-12 mice when compared with TNF-alpha levels of normal, MAIDS-2, and MAIDS-4 mice. In contrast, intraocular INF-gamma levels within MCMV-inoculated eyes progressively declined as animals became susceptible to retinitis. CONCLUSIONS: An inverse relationship exists between TNF-alpha and INF-gamma production within MCMV-inoculated eyes during MAIDS evolution that is characterized by an increase in intraocular TNF-alpha levels and a concomitant decrease in intraocular INF-gamma levels. Susceptibility of MCMV-inoculated eyes to virus replication and development of necrotizing retinitis are independent events with susceptibility to MCMV replication preceding susceptibility to MCMV retinitis by several weeks. Time of Th1/Th2 shift in cytokine profile appears to be a crucial event in the pathogenesis of MAIDS-related MCMV retinitis.

Cardiomyopathy in a murine model of AIDS: evidence of reactive nitrogen species and corroboration in human HIV/AIDS cardiac tissues.

OBJECTIVE: Cardiomyopathy and other vascular complications are now recognized as significant components of HIV/AIDS pathogenesis. Although the mechanisms involved in cardiomyopathy are poorly defined, a role for direct retroviral action and/or focal infiltration of activated immune cells have been postulated. Here we investigated mechanisms in retrovirus associated cardiomyopathy using a well-defined mouse model of acquired immunodeficiency. METHODS: Mice were dosed with LPBM5 retrovirus; cardiac performance was assessed by echocardiography followed by tissue collection at 5 and 10 weeks post-infection. RESULTS: Contractile deficits were observed at 5 and 10 weeks post-retrovirus infection and preceded the development of overt immunodeficiency. Selective and widespread cardiac infiltration of CD68+ cells, but not neutrophils, mast cells, or eosinophils was also observed at both 5 and 10 weeks. LPBM5 retrovirus was readily detectable in cardiac samples by RT-PCR. Time dependent increases in cardiac protein nitration (biomarker of reactive nitrogen species) were observed and were correlated to the extent of cardiac dysfunction whereas no changes in NOSII occurred at 5 and 10 weeks. We corroborated the mouse findings using cardiac tissues and clinical findings from human HIV/AIDS autopsies. CONCLUSIONS: These studies demonstrated that cardiac myocyte protein nitration in AIDS related cardiomyopathies, rather than focal immune cell lesions characterize retrovirus associated cardiomyopathies and differentiate them from non-retroviral cardiomyopathies.

Murine cytomegalovirus retinitis during retrovirus-induced immunodeficiency (MAIDS) in mice: interleukin-2 immunotherapy correlates with increased intraocular levels of perforin mRNA.

Mice with a retrovirus-induced immunosuppression (MAIDS) are susceptible to experimental murine cytomegalovirus (MCMV) retinitis, but can be rendered resistant to retinitis by systemic interleukin-2 (IL-2) immunotherapy. Experiments were performed to explore the mechanism by which IL-2 treatment during MAIDS might restore resistance to MCMV retinitis. Whereas 80% of untreated MAIDS mice were susceptible to MCMV retinitis, none (0%) of IL-2-treated MAIDS mice developed necrotizing retinitis. In comparison, 100% of both untreated and IL-2-treated perforin knockout mice (PKO mice) were susceptible to MCMV retinitis, and severity of retinitis and amounts of infectious intraocular MCMV in IL-2-treated PKO mice were equivalent to that in untreated PKO mice. A competitive quantitative RT-PCR assay was used to measure the levels of perforin mRNA within MCMV-infected eyes of immunologically normal mice, untreated MAIDS mice, and IL-2-treated MAIDS mice. Although the level of perforin mRNA within MCMV-infected eyes of untreated MAIDS mice susceptible to retinitis was significantly reduced when compared to the high level found within MCMV-infected eyes of normal mice resistant to retinitis, systemic treatment of MAIDS mice with IL-2 increased perforin mRNA within MCMV-infected eyes to levels found in normal mice. The ability of IL-2 treatment to increase intraocular levels of perforin mRNA diminished with the progression of MAIDS. Our findings support the hypothesis that systemic IL-2 immunotherapy during MAIDS provides protection against MCMV retinitis by upregulation of perforin-mediated cytotoxicity used by cytotoxic lymphocytes to kill virus-infected cells.

Loss of the perforin cytotoxic pathway predisposes mice to experimental cytomegalovirus retinitis.

AIDS-related human cytomegalovirus (HCMV) retinitis continues to be a chronic ophthalmologic problem among human immunodeficiency virus type 1 (HIV-1)-infected patients who do not respond to highly active antiretroviral therapy. Although HCMV retinitis occurs during HIV-1-induced immunosuppression, the precise effector mechanism(s) that fails during the immunopathogenesis of AIDS to allow onset and progression of HCMV retinal disease remains unclear. We therefore performed a series of experiments to explore the relative roles of distinct pathways of lymphocyte-mediated cytotoxicity in either resistance or susceptibility to experimental murine cytomegalovirus (MCMV) retinitis in mice. Whereas mutant C57BL/6 mice deficient in the Fas/FasL cytotoxic pathway (gld mice) were identical to normal C57BL/6 mice and exhibited absolute resistance to retinal necrosis following subretinal MCMV inoculation, knockout C57BL/6 mice deficient in the perforin cytotoxic pathway (PKO mice) were susceptible to MCMV retinitis. Susceptibility of PKO mice to MCMV retinitis correlated with increased ocular MCMV titers when compared with ocular MCMV titers of gld and normal mice. Since mice with retrovirus-induced immunodeficiency syndrome (MAIDS) exhibited a frequency and severity of MCMV retinitis that were equivalent to those observed in PKO mice, we hypothesized that susceptibility to MCMV retinitis during MAIDS correlates with a decrease in the perforin cytotoxic pathway. To test this hypothesis, we developed a quantitative competitive reverse transcription-PCR assay to measure mouse perforin mRNA levels in the splenic T lymphocytes and MCMV-inoculated eyes of normal mice or mice with MAIDS. Perforin mRNA levels in splenic T lymphocytes were significantly decreased during MAIDS, by approximately 100-fold, from perforin mRNA levels in normal mice. Moreover, MCMV-inoculated eyes destined to develop retinitis during MAIDS also showed a significant decrease in perforin mRNA levels from the perforin mRNA levels of MCMV-inoculated eyes of normal mice destined to be resistant to retinitis. As expected, perforin mRNA could not be detected in unmanipulated and uninfected eyes of normal mice. These results provide the first evidence that the perforin cytotoxic pathway is more important than the Fas/FasL cytotoxic pathway in providing resistance to experimental MCMV retinitis and that loss of the perforin cytotoxic pathway predisposes to MCMV retinitis.

Selenium supplementation decreases coxsackievirus heart disease during murine AIDS.

Coxsackievirus B3 (CVB3) induces myocarditis, especially in the immunodeficient or immature. To investigate whether CVB3 induced pronounced cardiomyopathy during the severe immune dysfunction of murine acquired immunodeficiency syndrome (AIDS), female C57BL/6 mice were infected with LP-BM5 retrovirus and then coinfected with CVB3. C57BL/6 mice, essentially resistant to CVB3-induced cardiomyopathy, became susceptible to this cardiomyopathy because of the immune dysfunction caused by murine AIDS. This susceptibility suggests that retrovirus infection causes conditions favoring the CVB3 induction of cardiac lesions. Mice were fed a diet supplemented with selenium (Se) at nine times the recommended daily dose for mice (0.933 mg/ kg of diet). Heart tissues were analyzed histopathologically 12 d after CVB3 challenge. Mice experiencing concurrent retrovirus and CVB3 infection had a high degree of cardiac lesions that were consistent with myopathy compared to that in uninfected mice (p < 0.05). Se supplementation during murine retrovirus infection significantly diminished the pathogenesis caused by concurrent CVB3 infection in mice that had murine AIDS. There was a significant increase in the survival of dually retrovirus and CVB3-infected mice that were fed Se, compared to that of identically treated mice that were not fed Se. Hepatic lipid peroxides were significantly diminished in the Se-supplemented mice as compared to those in immunodeficient mice without supplementation (p

Cocaine injection and coxsackievirus B3 infection increase heart disease during murine AIDS.

Coxsackievirus initiates myocarditis especially in the immunologically deficient or immature. To test whether Coxsackievirus B3 (CVB3) induced pronounced cardiomyopathy during severe immune dysfunction of murine AIDS, female C57BL/6 mice were infected with LP-BM5 retrovirus and superinfected with CVB3. Some were also injected daily with cocaine hydrochloride in 0.9% saline solution (30 mg/kg) intraperitoneally, because cocaine also suppresses cellular immune response. Heart tissue was analyzed histopathologically. Mice experiencing concurrent retrovirus and Coxsackievirus infection had a high degree of cardiac lesions consistent with myopathy compared with findings in uninfected animals (p <.05). Cocaine injection during murine retrovirus infection greatly exacerbated the pathogenesis of Coxsackievirus infection. C57BL/6 mice, essentially resistant to Coxsackievirus-induced cardiomyopathy, became susceptible during the immune dysfunction in murine AIDS. This suggests that retrovirus infection causes conditions favoring Coxsackie-induced cardiac lesions. Interleukin (IL)-2 and IL-4 expression by splenocytes from the dually infected retrovirus and Coxsackievirus group showed no significant differences when the animals were also cocaine treated. However tumor necrosis factor TNF-alpha production was significantly decreased in dually infected retrovirus + Coxsackievirus mice treated with cocaine, compared with findings in various controls (p <.05).

Lanoconazole, a new imidazole antimycotic compound, protects MAIDS mice against encephalitis caused by Cryptococcus neoformans.

The protective effect of a new antifungal compound, lanoconazole, against Cryptococcus neoformans infection in C57BL/6 mice exposed to LP-BM5 murine leukaemia virus (MuLV) (MAIDS mice) was investigated. Mice were infected intratracheally with C. neoformans, strain 613D, 40 days after infection with LP-BM5 MuLV. They were treated orally with various doses of lanoconazole or with fluconazole 10 mg/kg (a positive control) once daily beginning 1 day after the fungal infection and continuing until the end of the experimental period. The number of C. neoformans cells in the lungs and brains of infected mice was determined. Lanoconazole and fluconazole had a similar inhibitory effect on the growth of C. neoformans in the brains and lungs of normal mice. Whereas lanoconazole inhibited the growth of C. neoformans in the brains and lungs of MAIDS mice, the pathogen grew in the brains of MAIDS mice treated with fluconazole. Lanoconazole reduced the number of C. neoformans in the brains of normal mice treated with a type 2 cytokine mixture, whereas fluconazole did not. A predominance of type 2 T-cell responses was demonstrated in MAIDS mice. Splenic T cells from MAIDS mice, but not those from normal mice, released interleukins 4 and 10 into the culture medium when they were stimulated with an anti-CD3 monoclonal antibody. These results suggest that lanoconazole may have the potential to inhibit the growth of C. neoformans in AIDS patients with a predominance of type 2 T-cell responses.

Supplementation with Lactobacillus reuteri or L. acidophilus reduced intestinal shedding of cryptosporidium parvum oocysts in immunodeficient C57BL/6 mice.

The effect of L. acidophilus supplementation to reduce fecal shedding of Cryptosporidium parvum oocysts was compared to L. reuteri using C57BL/6 female mice immunosuppressed by murine leukemia virus (strain LP-BM5) inoculation. After 12 weeks post LP-BM5 inoculation, 15 immunosuppressed mice each were randomly assinged to one of the following treatment groups: historical control (group A), LP-BM5 control (group B), C. parvum (group C), L. reuteri plus C. parvum (group D) or L. acidophilus plus C. parvum (group E). Mice were pre-fed the L. reuteri or L. acidophilus bacteria strains daily for 13 days, challenged with C. parvum oocysts and thereafter fed the specified Lactobacillus regimens daily during the experimental period. Animals supplemented with L. reuteri shed fewer (p<0.05) oocysts on day-7 post C. parvum challenge compared to controls. Mice supplemented with L. acidophilus also shed fewer (p<0.05) oocysts on days 7 and 14 post-challenge compared to controls. Overall, Lactobacillus supplementation reduced C. parvum shedding in the feces but failed to suppress the production of T-helper type 2 cytokines [interleukin-4 (IL-4), IL-8)] which are associated with immunosuppression. Additionally, Lactobacillus supplementation did not restore T-helper type 1 cytokines (interleukin-2 (IL-2) and gamma interferon (IFN-gamma), which are required for recovery from parasitic infections. Altered T-helper types 1 and 2 cytokine production as a consequence of immunodysfunction permitted the development of persistent cryptosporidiosis while mice with intact immune system were refractory to infection with C. parvum. Reduction in shedding of oocysts observed in the Lactobacillus supplemented mice during deminished IL-2 and IFN-gamma production may be mediated by factors released into the intestinal lumen by the Lactobacillus and possibly other host cellular mechanisms. These observations suggest that L. reuteri or L. acidophilus can reduce C. parvum parasite burdens in the intestinal epithelium during cryptosporidiosis and may serve potential benefits as probiotics for host resistance to intestinal parasitic infections. L. acidophilus was more efficacious in reducing fecal shedding than L. reuteri and therefore may also have implication in the therapy of cryptosporidiosis during immunosuppressive states including human AIDS.

Extracellular glutamate levels are chronically elevated in the brains of LP-BM5-infected mice: a mechanism of retrovirus-induced encephalopathy.

Mice infected with the LP-BM5 leukemia retrovirus mixture develop a progressive immunodeficiency with associated behavioral, histological, and neurochemical alterations consistent with glutamatergic hyperactivation. To gain insight into the contribution of excitatory amino acids to the neurodegeneration observed in these mice, their concentrations were measured in the CSF and striatal microdialysates. Glutamate concentrations were significantly elevated in CSF but not plasma as early as 4 weeks postinoculation. Steady-state glutamate levels in striatal microdialysates were increased threefold and could be reduced 40% by application of L-alpha-aminoadipate, an inhibitor of microglial glutamate transport. Stimulation of infected mice with KCl/L-trans-2,4-pyrrolidine dicarboxylate further increased glutamate levels 170-270% above those evoked in control mice. Tetrodotoxin suppressed the depolarization-evoked increase in glutamate by 88% in control mice, but it had only negligible effects in 40% of infected mice. Analysis of glutamate transport and catabolism suggests that abnormal astrocytic function does not contribute to the increase in basal extracellular glutamate levels. These findings are the first direct evidence that infection with an immunodeficiency-inducing retrovirus leads to a chronic elevation of extracellular free glutamate levels in the brain, which contributes to the neurodegenerative and cognitive deficits observed in these mice.

Dehydroepiandrosterone (DHEA) sulfate prevents reduction in tissue vitamin E and increased lipid peroxidation due to murine retrovirus infection of aged mice.

Dietary effects of dehydroepiandrosterone sulfate (DHEAS) supplementation on tissue antioxidants and lipids were investigated in retrovirus infected mice. DHEA is a powerful antioxidant and immunomodulator whose production declines with age. For this study, twenty-four female, 15-month-old C57BL/6 mice were left uninfected while twenty-four were infected with LP-BM5 murine leukemia virus, causing murine AIDS. The retroviral infection caused immune dysfunction and loss of hepatic and cardiac vitamins E and A, resulting in increased lipid peroxides. Treatment with DHEAS at 0.01 or 0.005% in drinking water for 10 weeks post-infection significantly (P < 0.05) lowered lipid peroxidation in both heart and liver tissues. Treatment with DHEAS also largely prevented loss of the antioxidants, such as vitamin E and A, and prevented loss of phospholipid in the hearts and livers of the old uninfected as well as infected mice. This study suggests that DHEAS supplementation reduces damage associated with elevated oxidation due to aging and retrovirus infection.

The encephalopathy associated with murine acquired immunodeficiency syndrome.

Mice infected with the LP-BM5 murine leukemia virus (MuLV) develop an immune deficiency syndrome together with an encephalopathy characterized by impairments in spatial learning and memory. These cognitive deficits are evident before the appearance of neuron loss and lymphoid cell invasion of the brain. Nonetheless, a prominent gliosis and a variety of neurochemical changes precede the development of cognitive deficits. The neurochemical abnormalities include significant decreases in striatal Met-enkephalin and substance P (but not somatostatin), increases in concentrations of quinolinic acid and platelet-activating factor, and alterations in brain fyn kinase. At this stage of the infection, some of these neurochemical changes can be reversed by glutamate receptor antagonists, cytokine inhibitors, and anti-retroviral agents. In later stages of the infection, however, the infected mice develop irreversible neuronal loss, invasion of hematopoietic cells, and increased viral burden in the CNS. In addition, motor-neuron dysfunction (hindlimb paralysis, weakness, and ataxia) and seizures are sometimes observed during the late stages of infection. Thus, the LP-BM5 MuLV-infected mouse is a useful model for studying the chronology of neurodegenerative changes, ranging from reversible neuron dysfunction to irreversible neuron loss, that are associated with retrovirus-induced immunodeficiency.

HIV-1-infection in the CNS. A pathogenesis of some neurological syndromes in the light of recent investigations.

The main factors in the pathogenesis of AIDS-dementia complex (ADC) are analyzed. The author suggests that these factors can be divided into two groups. The "nonspecific" factors present in every immunologic processes manifested by inflammation compose the first group. They are cytotoxic lymphocytes T, the immunoactivation of infected macrophages, cytokines, NO, NOS and iNOS, the increase of the BBB permeability, the accumulation of beta-amyloid precursor protein, excitotoxic amino acids, various and numerous cells adhesion molecules. The second group may contain factors connected with HIV-1 infection of CNS. In the pathogenesis of AIDS an important role is played by toxic glycoproteins gp 120 and gp 41 which are in the coat of HIV-1 virus, nucleotide sequences variability, possibility of various virus replication in various parts of CNS, the participation of lymphokines IL-4 and IL-10, and presence of co-receptors to HIV-1 virus on lymphocytes, macrophages, neurons and microglial cells.

Protective effects of granulocyte colony-stimulating factor on endotoxin shock in mice with retrovirus-induced immunodeficiency syndrome.

Mice with retrovirus-induced murine acquired immunodeficiency syndrome (MAIDS) were hypersensitive to lipopolysaccharide (LPS)-induced lethal shock accompanied by marked elevations of systematic interleukin 1beta (IL-beta) and interferon gamma (IFN-gamma) after LPS challenge. Pretreatment with 10 microg of recombinant human granulocyte colony-stimulating factor (rhG-CSF) protected MAIDS mice from hypersensitivity to LPS-induced lethal shock and this protection was concomitant with suppression of IFN-gamma production.

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.