A malignant astrocytoma containing simian virus 40 DNA in a macaque infected with simian immunodeficiency virus.

Polyomaviruses have proven oncogenicity in nonhost experimental animals; however, studies concerning the association between human brain tumors and simian and human polyomaviruses have yielded inconclusive results. We examined the relationship of SV40 to a malignant astrocytoma found in the right frontal lobe of a pigtail macaque (Macaca nemestrina) infected with simian immunodeficiency virus (SIV). Consistent with the histologic diagnosis, the tumor was immunoreactive with antibodies to S-100 protein, vimentin, and glial fibrillary acidic protein, but negative for neurofilament protein, synaptophysin, neuron-specific enolase, and chromogranin A. At the time of SIV inoculation, the animal was seropositive for SV40. Polymerase chain reaction assay of tumor DNA, but not normal brain DNA, yielded a 300 base-pair fragment corresponding to the carboxy-terminal coding region (C-terminus) of the large T antigen gene of SV40, suggesting an association with the tumor.

An immunohistologic study of granulomatous inflammation in SIV-infected rhesus monkeys.

We studied granulomatous inflammation in simian AIDS using histologic, immunohistologic, and in situ hybridization techniques. Complete Freund's adjuvant was used to induce granulomas in two control animals and two macaques infected with simian immunodeficiency virus (SIV) and having low peripheral CD4+ T cell counts. Control animals developed large (> 2 cm diameter) epithelioid granulomas containing CD68+ macrophages (m phi s), epithelioid m phi s and multinucleated giant cells (MNGCs), CD4+ and CD8+ T cells, and small perivascular collections of CD20+ B cells. Lymphocytes rarely expressed proliferating cell nuclear antigen (Ki-67), and only rare endothelial cells expressed vascular cell adhesion molecule 1 (VCAM-1). In contrast, SIV+ animals had smaller (< 0.5 cm diameter) epithelioid granulomas characterized by numerous large, dense CD8+, CD20+ lymphocyte aggregates with prominent local division (Ki-67+). Despite low blood CD4+ T cell numbers, there was a substantial CD4+ T cell infiltrate, accompanied by enhanced endothelial VCAM-1 expression. These granulomas contained no detectable SIV antigen or RNA. Thus, in simian AIDS, experimentally induced granulomatous responses are grossly attenuated, yet associated with increased local endothelial-leukocyte signaling and lymphocyte division.

Influence of extracellular matrix in tumor necrosis factor-induced increase in endothelial permeability.

We examined the possibility that alterations of the extracellular matrix (ECM) contribute to the tumor necrosis factor-alpha (TNF-alpha)-induced increase in endothelial monolayer permeability. Endothelial permeability to 125I-labeled albumin was determined using bovine pulmonary microvessel endothelial cell (BPMVE) monolayers grown to confluence on microporous (0.8 microns diam) gelatin- and fibronectin-coated polycarbonate filters. Treatment of BPMVE with TNF-alpha (10(2) to 10(4) U/ml for 4-24 h) produced concentration- and time-dependent increases in endothelial permeability that paralleled the changes in morphology from cobblestone to elongated cells and the formation of prominent intercellular gaps and actin stress fibers. We examined the role of ECM in these changes using filters coated with ECM made by the BPMVE. Fresh BPMVE seeded onto filters coated with ECM produced by TNF-alpha-treated BPMVE had two- to threefold higher 125I-albumin permeability values than BPMVE monolayers seeded onto filters coated with ECM from control cells (P < 0.05). BPMVE seeded onto ECM from TNF-alpha-treated BPMVE also developed intercellular gaps and centralized actin filaments characteristic of the TNF-alpha-treated BPMVE. This effect was not attributable to TNF-alpha adsorbed to ECM. Polyacrylamide gel electrophoresis of ECM extracted from BPMVE treated with TNF-alpha showed decreased fibronectin. These findings suggest that the TNF-alpha-induced increase in endothelial permeability involves the loss of fibronectin and remodeling of the ECM. The increase in endothelial permeability may be secondary to decreased endothelial cell-ECM contacts resulting in elongation of cells and formation of intercellular gaps.

Effects of monensin on selenium status and related factors in genetically hypo- and hyperselenemic growing swine.

Monensin is an ionophoretic antibiotic, which selectively transports alkali metal cations across biological membranes. In growing swine, monensin toxicosis causes acute, degenerative cardiac and skeletal myopathy resembling vitamin E-selenium deficiency. Selenium is an essential trace element incorporated in glutathione peroxidase (GSH-Px), an antioxidant enzyme system that protects subcellular membranes. In our study, we examined the effects of monensin on body weight, Se balance, antioxidant status, and serum concentrations of selected minerals in growing pigs that were genetically hypo- or hyperselenemic (hypo-Se and hyper-Se, respectively). Three groups of eight 8-week-old pigs, each comprised of 4 hypo-Se and 4 hyper-Se pigs (76.4 +/- 3.0 and 106.3 +/- 10.3 ng of Se/ml of serum, respectively), were fed standard diets containing 0.1 mg of supplemental Se/kg of body weight, and either 0, 200, or 400 mg of monensin/kg for a 77-day period, followed by a 28-day monensin withdrawal period. On days 0, 7, 28, 56, 70, and 98, all pigs were weighed and blood was collected for determination of serum GSH-Px, creatine phosphokinase, and aspartate transaminase values, as well as serum concentrations of vitamin E, Se, Ca, Cu, Fe, K, Mg, Na, P, and Zn. Significance of main effects of monensin treatment, genetic Se status, and their interactions was tested by Fisher's variance ratio test, followed by conditional comparison of treatment means with a Bonferroni test. Signs of monensin toxicosis were not observed and monensin consumption had no effect on body weight, or serum creatine phosphokinase, aspartate transaminase, or Se values. However, pigs consuming monensin had consistently higher serum GSH-Px activities, possibly because of increased synthesis of this adaptive antioxidant enzyme. Interactions were not found between monensin and genetic Se status. Hyperselenemic pigs were heavier and had higher serum Se and GSH-Px values than hypo-Se pigs. Furthermore, hypo-Se and hyper-Se pigs were hypo- and hypercupremic, respectively, suggesting genetic regulation of copper status. It is likely that pigs with inadequate antioxidant status (hyposelenemia, hypocupremia) are more susceptible to diseases associated with cellular membrane damage, such as vitamin E-Se deficiency disease and monensin toxicosis.

Genetic analysis of simian virus 40 from brains and kidneys of macaque monkeys.

Simian virus 40 (SV40) was isolated from the brains of three rhesus monkeys and the kidneys of two other rhesus monkeys with simian immunodeficiency virus-induced immunodeficiency. A striking feature of these five cases was the tissue specificity of the SV40 replication. SV40 was also isolated from the kidney of a Taiwanese rock macaque with immunodeficiency probably caused by type D retrovirus infection. Multiple full-length clones were derived from all six fresh SV40 isolates, and two separate regions of their genomes were sequenced: the origin (ori)-enhancer region and the coding region for the carboxy terminus of T antigen (T-ag). None of the 23 clones analyzed had two 72-bp enhancer elements as are present in the commonly used laboratory strain 776 of SV40; 22 of these 23 clones were identical in their ori-enhancer sequences, and these had only a single 72-bp enhancer element. We found no evidence for differences in ori-enhancer sequences associated with tissue-specific SV40 replication. The T-ag coding sequence that was analyzed was identical in all clones from kidney. However, significant variation was observed in the carboxy-terminal region of T-ag in SV40 isolated from brain tissues. This sequence variation was located in a region previously reported to be responsible for SV40 host range in cultured cell lines. Thus, SV40 appears to be an opportunistic pathogen in the setting of simian immunodeficiency virus-induced immunodeficiency, similarly to JC virus in human immunodeficiency virus-infected humans, the enhancer sequence organization generally attributed to SV40 is not representative of natural SV40 isolates, and sequence variation near the carboxy terminus of T-ag may play a role in tissue-specific replication of SV40.

Simian virus 40-induced disease in rhesus monkeys with simian acquired immunodeficiency syndrome.

Simian virus 40 (SV40) disease was diagnosed in four rhesus monkeys that died with SIV-induced acquired immunodeficiency syndrome (AIDS). One juvenile monkey seroconverted for SV40 6 months after inoculation with SIV and developed severe bilateral tubulointerstitial nephritis. In contrast, progressive multifocal leukoencephalopathy (PML) occurred in two adult monkeys that were seropositive for SV40 before SIV inoculation, as well as a third adult that was naturally infected with SIV and seropositive for SV40 5 years before death. Large intranuclear inclusions containing abundant polyomavirus particles were limited to either renal tubular epithelial cells or oligodendrocytes. In situ DNA hybridization for SV40 large T antigen further demonstrated that SV40 nucleic acid was localized to either kidney or brain tissue. By immunohistochemical analysis, areas of central nervous system inflammation and demyelination were shown to contain CD68+ macrophages (gitter cells), aggregates of CD8+ T lymphocytes, and numerous gemistocytic astrocytes that labeled for glial fibrillary acidic protein. These observations indicate that rhesus monkeys with SIV-induced AIDS are predisposed to polyomaviral disease, in which SV40 nucleic acid is observed in renal tissue in primary infections and brain tissue after viral reactivation. Furthermore, this organ-specific replication suggests that tissue-tropic strains of SV40 may develop in immunodeficient monkeys.

Role of platelet-activating factor in mediating tumor necrosis factor alpha-induced pulmonary vasoconstriction and plasma-lymph protein transport.

We assessed the role of platelet-activating factor (PAF) in mediating the pulmonary hemodynamic and lymph flow responses to tumor necrosis factor-alpha (TNF alpha). The effects of the PAF receptor antagonist WEB 2086 on TNF alpha-induced pulmonary vasoconstriction and increased pulmonary transvascular plasma-lymph protein transport were examined. Control (n = 7) and WEB-2086-pretreated (n = 7) sheep prepared with chronic lung lymph fistulas were challenged with recombinant human TNF alpha (12 micrograms/kg over 0.5 h). Ex vivo challenge of platelet-rich plasma (PRP) with 10(-8) M PAF resulted in aggregation of platelets from control TNF-challenged sheep, but not of platelets from WEB-treated sheep similarly challenged with TNF. The control TNF-alpha-challenged sheep developed hemoconcentration, leukopenia, and neutropenia. TNF alpha resulted in increases in pulmonary arterial pressure (Ppa) and pulmonary vascular resistance (PVR) within 15 min, and the values were sustained for the 5-h experiment duration. Pulmonary lymph flow (Qlym) and pulmonary transvascular protein clearance rate (Qlym x lymph-to-plasma protein concentration) were increased within 30 min and remained elevated for 5 h. The WEB-2086-treated sheep developed similar leukopenia and neutropenia after TNF alpha challenge, but the initial increases in Ppa and PVR were significantly reduced (p less than 0.05). However, WEB 2086 did not prevent the threefold increases in Qlym and transvascular protein clearance induced with TNF alpha.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytokine influence on simian immunodeficiency virus replication within primary macrophages. TNF-alpha, but not GMCSF, enhances viral replication on a per-cell basis.

The control of HIV-1 or SIV replication within macrophages is probably influenced by a variety of viral and cellular factors. Of the cellular factors, the authors have studied cytokine influence on SIV replication in vitro utilizing simian alveolar macrophages and uncloned SIVmacMTV, a macrophage-tropic variant. The approach allowed quantification of viral replication on a per-cell basis. As reported for HIV-1 replication in macrophages, TNF-alpha significantly increased SIV production in these macrophage cultures. GMCSF also resulted in marked increases in SIV gag protein in culture supernatants. However, after correcting for differences in total cell numbers and numbers of gag-containing cells in the treated and untreated cultures, GMCSF did not upregulate SIV production on a per-cell basis. IL-6 increased SIV replication little if at all but induced significantly greater cytopathic changes in the treated cultures compared with infected, untreated cultures. In contrast, IFN-gamma greatly decreased replication. Our results for GMCSF, IFN-gamma, and IL-6 are in contrast to previously published reports of cytokine control of HIV-1 growth in target cells, and they stress the importance of cell number analyses and the use of primary cultures in the study of lentiviral replication kinetics in macrophages.

Effect of simian immunodeficiency virus infection on tumor necrosis factor-alpha production by alveolar macrophages.

We studied the release of tumor necrosis factor-alpha (TNF alpha), a vital immunoregulatory cytokine, by alveolar macrophages (M phi s) infected with simian immunodeficiency virus (SIV) in vitro or collected from SIV-infected macaques. For in vitro studies, M phi s were harvested by bronchoalveolar lavage from 5 normal animals and infected in flasks with SIV (10(4)TCID50/2.5 x 10(6) M phi s). After 7 to 10 days, cytopathic effect was prominent and 68 +/- 2% of M phi s were immunoreactive for p27 core protein. Uninfected (control) and SIV-infected M phi s were then cultured for 24 hours in 96-well plates (10(5) M phi s/well) while challenged with lipopolysaccharide (LPS; 100 micrograms/ml). TNF alpha was assayed in culture supernatants by an enzyme-linked immunosorbent assay (detection limit, 50 pg/ml) and results were expressed as pg TNF alpha/ml/10(3) M phi s (mean +/- SEM). TNF alpha was not detected in unstimulated wells. TNF alpha release by control and SIV-infected M phi s was similar (6.6 +/- 0.7 and 7.9 +/- 1.1 pg/ml/10(3) M phi s, respectively). We also studied TNF alpha release by alveolar M phi s from 8 animals infected with SIV (3 asymptomatic, 5 with acquired immune deficiency syndrome virus (AIDS]. One animal with AIDS had p27+ M phi s. Alveolar M phi s from asymptomatic animals released significantly more TNF alpha (10.3 +/- 1.1 pg/ml/10(3) M phi s) than did animals with AIDS or uninfected macaques (5.2 +/- 0.8 and 7.0 +/- 0.6 pg/ml/10(3) M phi s, respectively) (p less than 0.01). However, M phi s from monkeys with AIDS failed to respond to LPS after 7 to 10 days in culture. In summary, in vitro infection with SIV does not cause constitutive TNF alpha release or alter the response of cultured M phi s to LPS. When kept in culture, M phi s collected from asymptomatic, SIV-infected animals retain their response to LPS, whereas M phi s from animals with AIDS lose the capacity to produce TNF alpha. Furthermore, M phi s cytokine production is exaggerated before overt clinical disease, but not as a direct result of infection with SIV.

Recombinant tumor necrosis factor increases pulmonary vascular permeability independent of neutrophils.

We studied the effects of intravenous infusion of recombinant human tumor necrosis factor type alpha (rTNF-alpha; 12 micrograms/kg) on lung fluid balance in sheep prepared with chronic lung lymph fistulas. The role of neutrophils was examined in sheep made neutropenic with hydroxyurea (200 mg/kg for 4 or 5 days) before receiving rTNF-alpha. Infusion of rTNF-alpha resulted in respiratory distress and 3-fold increases in pulmonary arterial pressure and pulmonary vascular resistance within 15 min, indicating intense pulmonary vasoconstriction. Pulmonary lymph flow (i.e., net transvascular fluid filtration rate) and transvascular protein clearance rate (a measure of vascular permeability to protein) increased 2-fold within 30 min. The increased permeability was associated with leukopenia and neutropenia. The pulmonary hypertension and vasoconstriction subsided but fluid filtration and vascular permeability continued to increase. Sheep made neutropenic had similar increases in pulmonary transvascular fluid filtration and vascular permeability. rTNF-alpha also produced concentration-dependent increases in permeability of 125I-labeled albumin across ovine endothelial cell monolayers in the absence of neutrophils or other inflammatory mediators. The results indicate that rTNF-alpha increases pulmonary vascular permeability to protein by an effect on the endothelium.

Adrenocorticotropin-containing neoplastic cells in a pars intermedia adenoma in a horse.

Pituitary-dependent hyperadrenocorticism was diagnosed in a 14-year-old Arabian mare with chronic weight loss, hirsutism, polyuria, and polydipsia. The mare had a stress leukogram, glucosuria, and consistent hyperglycemia. Plasma glucose concentrations were resistant to suppression by insulin. Plasma cortisol concentrations were within normal limits, but did not respond to dexamethasone suppression and had an exaggerated response to ACTH stimulation. At necropsy, a chromophobe adenoma of the pars intermedia of the pituitary gland was found. The zona fasciculata of the adrenal cortex and the pancreatic islets of Langerhans were hypertrophied. An immunohistologic staining technique was used to demonstrate ACTH-containing neoplastic cells in the pituitary mass. These cells released ACTH and other peptides that initiated the chain of endocrinologic events leading to clinical disease.