The neuro-steroid, 3beta androstene 17alpha diol exhibits potent cytotoxic effects on human malignant glioma and lymphoma cells through different programmed cell death pathways

The neuro-steroids 3β-androstene-17α-diol (17α-AED), 3β-androstene-17β-diol (17β-AED), 3β-androstene-7α,-17β-triol (7α-AET) and 3β-androstene-7β,-17β-triol (7β-AET) are metabolites of dehydroepiandrosterone and are produced in neuro-ectodermal tissue. Both epimers of androstenediols (17α-AED and 17β-AED) and androstenetriols (7α-AET and 7β-AET) have markedly different biological functions of their chemical analogue. We investigated the cytotoxic activity of these neuro-steroids on human T98G and U251MG glioblastoma and U937 lymphoma cells. Proliferation studies showed that 17α-AED is the most potent inhibitor, with an IC₅₀ ∼15 μM. For T98G glioma, 90% inhibition was achieved with 25 μM of 17α-AED. Other neuro-steroids tested only marginally suppressed cell proliferation. Reduced cell adherence and viability could be detected after 18 h of 17α-AED exposure. Treatment with 17α-AED induced a significant level of apoptosis in U937 lymphoma cells, but not in the glioma cells. Cytopathology of 17α-AED-treated T98G cells revealed the presence of multiple cytoplasmic vacuoles. Acridine orange staining demonstrated the formation of acidic vesicular organelles in 17α-AED-treated T98G and U251MG, which was inhibited by bafilomycin A1. These findings indicate that 17α-AED bears the most potent cytotoxic activity of the neuro-steroids tested, and the effectiveness may depend on the number of hydroxyls and their position on the androstene molecule. These cytotoxic effects may utilize a non-apoptotic pathway in malignant glioma cells.

Androstenetriol and androstenediol. Protection against lethal radiation and restoration of immunity after radiation injury

Androstenetriol (AET) and Androstenediol (AED) upregulate host immunity, leading to increased resistance against infections. AET augments IL-2, IL-3, IFN gamma levels, and counteracts hydrocortisone immune suppression. AET and AED at a dose of 0.75 mg/- and 8.0 mg/25-g mouse, protected 60 and 70%, respectively, of C57/BL/6J mice irradiated with a lethal dose. These hormones also protected mice irradiated with 6 Gy and infected with a coxsackievirus B4 LD50. AET significantly increased spleen lymphocyte numbers at 7, 14, and 21 days after a 6-Gy exposure. Fluorescent activated cell-sorter analysis of irradiated mice, spleen, and bone marrow showed that AET significantly augmented the myeloid precursor markers, CD11b/Mac-1, and B220 (pan B), as well as the absolute numbers of CD4+/CD8+ cells over the 21 days of testing. Overall, the data are consistent with AET/AED inducing a more rapid recovery of all hematopoietic precursors from the small number of surviving stem cells.

Steroid hormone regulation of antiviral immunity

Recent observations in both humans and animals have demonstrated that stress is immunomodulatory and can alter the pathogenesis of microbial infections to the extent that it may be adverse to health. Stress disrupts homeostasis, and the body responds through endocrine and nervous system interactions in an effort to re-establish the health of the host. However, the resulting physiologic changes associated with stress, such as the rise in serum glucocorticoids (GCs), are implicated in suppression of antiviral immunity. Therefore, it would be of significance to counterregulate stress-mediated immunosuppression during viral infection to improve immune responses and limit virus-mediated damage. The data in this study focus upon the antiglucocorticoid influence of a native steroid hormone that has been shown to augment immune function and protect animals against lethal viral infections. Androstenediol (5-androstene-3 beta,17 beta-diol, AED), a metabolite of dehydroepiandrosterone (DHEA), confers protection against lethal infection with influenza A virus. The protective activity appears to counterbalance the function of the regulatory GCs because AED prevents GC-mediated suppression of IL-1, TNF-alpha, and IL-2 secretion. Furthermore, AED inhibits GC-induced transcription of a GC-sensitive reporter gene.

17 alpha androstenediol inhibition of breast tumor cell proliferation in estrogen receptor-positive and -negative cell lines

Androstene-3beta, 17alpha-diol (17alpha-AED) inhibits DNA synthesis and induces apoptosis in several myeloid cancer cell lines. The purpose of this study was to determine if 17alpha-AED inhibition of human breast carcinoma cell proliferation is dependent on the estrogen or androgen receptor. At concentrations of 12.5 to 50 x 10(-9) M 17alpha-AED inhibited the proliferation of ZR75-1, estrogen receptor-positive (ER+) cells, by 54% to 68%. Further, 17alpha-AED inhibited MDA-MB231, estrogen receptor-negative (ER-) cells, by 33.6% to 56.0%. The inhibitory effect was dose dependent with a minimal effective inhibitory dose at 12.5x10(-9) M for both cell lines. Both 17beta-AED and estradiol potentiate the inhibitory effect of 17alpha-AED on ER+ cells at lower doses (3.13 to 6.25 x 10(-9) M) where 17alpha-AED alone was not inhibitory. The inhibitory action of 17alpha-AED on human mammary carcinomas appears to be independent of either the alpha estrogen or the androgen receptors.

Androstenediol-induced restoration of responsiveness to influenza vaccination in mice

Androstenediol (AED), a metabolite of dehydroepiandrosterone (DHEA) regulates innate and adaptive immune responses. To examine whether AED could effectively reverse the age-associated decline of antiviral immunity, 3-, 10-, and 22-month-old mice were treated with AED-sulfate (AED-S) for 45 days beginning 10 days prior to vaccination. Subsequently, mice were primed and boosted with suboptimal doses of a commercially-available trivalent influenza vaccine. Treatment of 10-month-old animals with AED-S during vaccination increased the titer of circulating antiviral immunoglobulin G to levels comparable with those in 3-month-old mice. Furthermore, AED-S treatment protected 10-month-old animals from intranasal challenge with a lethal dose of influenza virus 21 days after secondary vaccination. Although AED-S treatment of 22-month-old mice did not enhance vaccine responses and failed to protect against lethal challenge, the data from the 10-month-old animals suggest that treatment with AED-S will prevent the early manifestations of immunosenescence.

Androstenediol stimulates myelopoiesis and enhances resistance to infection in gamma-irradiated mice

The ionizing radiation-induced hemopoietic syndrome is characterized by defects in immune function and increased mortality due to infections and hemorrhage. Since the steroid 5-androstene-3beta, 17beta-diol (5-androstenediol, AED) modulates cytokine expression and increases resistance to bacterial and viral infections in rodents, we tested its ability to promote survival after whole-body ionizing radiation in mice. In unirradiated female B6D2F1 mice, sc AED elevated numbers of circulating neutrophils and platelets and induced proliferation of neutrophil progenitors in bone marrow. In mice exposed to whole-body (60)Co gamma-radiation (3 Gy), AED injected 1 h later ameliorated radiation-induced decreases in circulating neutrophils and platelets and marrow granulocyte-macrophage colony-forming cells, but had no effect on total numbers of circulating lymphocytes or erythrocytes. In mice irradiated (0, 1 or 3 Gy) and inoculated four days later with Klebsiella pneumoniae, AED injected 2 h after irradiation enhanced 30-d survival. Injecting AED 24 h before irradiation or 2 h after irradiation increased survival to approximately the same extent. In K. pneumoniae-inoculated mice (irradiated at 3-7 Gy) and uninoculated mice (irradiated at 8-12 Gy), AED (160 mg/kg) injected 24 h before irradiation significantly promoted survival with dose reduction factors (DRFs) of 1.18 and 1.26, respectively. 5-Androstene-3beta-ol-17-one (dehydroepiandrosterone, DHEA) was markedly less efficacious than AED in augmenting survival, indicating specificity. These results demonstrate for the first time that a DHEA-related steroid stimulates myelopoiesis, and ameliorates neutropenia and thrombocytopenia and enhances resistance to infection after exposure of animals to ionizing radiation.

Control of the immune response by DHEA and its metabolites

The 17 keto steroid, Dehydroepiandrosterone (5-androsten-3 beta-17-one, DHEA) has been shown to protect mice from a variety of lethal infections. This includes, but is not limited to, infection with viruses (herpesvirus type 2, coxsackievirus B4-CVB4),bacteria (Enterococcus faecalis, Pseudomonas aeruginosa), and a parasite (Cryptosporidium parvum). We have reported that androstenediol (5-androsten-3 beta-17 beta-diol, beta AED), which is derived from DHEA, is at least 100x more effective in up-regulating systemic resistance against CVB4-infection than its precursor. Furthermore, androstenetriol (5-androstene-3 beta-7 beta-17 beta-triol beta AET) which is formed by 7 beta hydroxylation of beta AED, was more effective against CVB4-infection than its precursor beta AED. Neither steroid however has shown any significant direct antiviral effects. The in-vitro influences of DHEA, beta AED, and beta AET on a mitogen-induced mixed splenocyte proliferation assay were determined. The results showed that DHEA suppressed the proliferation of concanavalin A (Con A) or lipopolysaccharide (LPS) activated cultures in a dose dependent manner. beta AED had little influence on the activation response. However, beta AET potentiated the response to both mitogens significantly above control. The regulation of interleukin-2 and interleukin-3 secretion from Con A-activated lymphocytes was analogous to these observations. These functions were suppressed by DHEA, unaffected by beta AED, and potently increased by beta AET. Moreover, the classic immuno-suppressive effects of hydro-cortisone on Con A-induced lymphocyte proliferation, as well as IL-2 and IL-3 production were unaffected by co-cultured with DHEA and only minimally counteracted by beta AED. In contrast, beta AET significantly counteracted the effect of hydrocortisone when co-cultured together. These results show that while in-vivo, DHEA, beta AED, and beta AET each function in a similar manner. In-vitro, their effects are dramatically different from one another with only beta AET potentiating the cellular response by increasing lymphocyte activation and counteracting the immuno-suppressive activity of hydrocortisone.

Endocrine regulation of murine macrophage function: effects of dehydroepiandrosterone, androstenediol, and androstenetriol

In these studies, the in vitro influences of dehydroepiandrosterone (DHEA), androstenediol (AED), and androstenetriol (AET) on proinflammatory cytokine production from macrophages was examined. From physiologic to pharmacologic doses, DHEA suppressed secretion of each pro-inflammatory cytokine while AED had little influence on the responses. In sharp contrast, AET augmented TNF-alpha and IL-1 secretion while not influencing IL-6 production. Furthermore, the antiglucocorticoid activity of DHEA, AED, and AET was also investigated. Co-culture with AET counteracted the down-regulatory effect of hydrocortisone on LPS-induced TNF-alpha and IL-1 secretion. These data imply that AET is capable of regulating cytokine secretion from macrophages and may function to counterbalance glucocorticoid function.

Endocrine regulation of the immune response to influenza virus infection with a metabolite of DHEA-androstenediol

In these studies the influence of androstenediol on the course of an experimental virus infection was examined. Pretreatment with 320 mg/kg AED protected male mice from lethal influenza virus infection. In addition, AED enhanced antigen-induced trafficking of mononuclear cells into the draining lymph node and augmented antigen-specific activation of helper-T cells, which are important for control of viral pathogenesis. Furthermore, AED prevented the characteristic increase in serum corticosterone noted during influenza A virus infection. Although steroid hormones, at least corticosteroids, typically suppress host immune and inflammatory responses in vivo, these data suggest that AED may function to augment host immune and inflammatory responses in contrast to corticosteroids.

Contrasting effects of alpha- and beta-androstenediol on oncogenic myeloid cell lines in vitro

The in vitro effects of 17 alpha AED, the isomer of 5-androstene-3 beta,17 beta diol (17 beta AED) on the basal growth of murine RAW 264.7, P388D1, and human HL-60 cells were investigated. 17 alpha AED treatment of RAW cells for 48 h reduced total cell number without increasing cell death as detected by trypan blue exclusion. At these doses, DNA synthesis as measured by [3H]thymidine incorporation was suppressed by as much as 65%, P < 0.05. This effect was time- and dose-dependent and reversible on removal of the steroid. Similar results were obtained with P388D1 and human HL-60 cell lines. At 50 nM or above, 17 alpha AED induced apoptosis in RAW cells and HL-60 as detected by transmission electron microscopy and TUNEL assays. By contrast, treating cells with the isomer 17 beta AED had no such effect. These data suggest that the balance between the anti-proliferative effect of 17 alpha AED and the proliferative effects of 17 beta AED may determine the overall level of myelopoiesis.

Antiglucocorticoid function of androstenetriol

The anti-inflammatory and immunosuppressive functions of corticosteroids have been well established and characterized. In contrast, a different group of native steroids, which include dehydroepiandrosterone (DHEA) and two of its metabolites, androstenediol (5-androstene-3 beta-17 beta-diol, AED) and androstenetriol (5-androstene-3 beta-7 beta-17 beta-triol, beta AET), function in vivo to up-regulate host immune response against infections and counteract stress-induced immunosuppression. Indeed, DHEA and particularly, AED and beta AET, have been shown to protect mice from viral, bacterial, and parasitic infections. In vivo, these three hormones are in opposition to the widely demonstrated immunosuppressive action of glucocorticoids, suggesting a possible new immune regulation mechanism. The individual activity in vitro of each of these steroids, i.e. DHEA, AED, and beta AET, on a mitogen-induced mixed splenocyte proliferation assay were determined. The results showed that DHEA suppressed the proliferation of cultures activated with concanavalin A (ConA) or lipopolysaccharide (LPS) in a dose-dependent manner. AED had little influence on the activation response. However, beta AET potentiated the response to both mitogens significantly above control. The regulation of the cytokine secretion, of both interleukin-2 (IL-2) and interleukin-3 (IL-3), from ConA-activated lymphocytes was affected in the same manner. These functions were depressed by DHEA, unaffected by AED, and potently increased by beta AET. Moreover, the classic immunosuppressive effects of hydrocortisone on ConA-induced lymphocyte proliferation, as well as on IL-2 and IL-3 production, were unaffected by being co-cultured with DHEA and only minimally counteracted by AED at high doses. In contrast, co-culturing with beta AET significantly counteracted the immunosuppressive effects of hydrocortisone on lymphocyte proliferation and cytokine production. These data show that in-vivo, DHEA, AED, and beta AET may have some similar functions, while in vitro, their effects are dramatically different from one another. Only beta AET could markedly potentiate the cellular response by increasing lymphocyte activation and counteracting the immnosuppressive activity of hydrocortisone on lymphocyte proliferation and cytokine production.

Regulation of the immune response by dehydroepiandrosterone and its metabolites

Dehydroepiandrosterone (5-androsten-3 beta-ol-17-one, DHEA) has been shown to protect mice from a variety of lethal infections. This includes, but is not limited to, infection with viruses (herpes virus type 2, coxsackie virus B4 (CB4)), bacteria (Enterococcus faecalis, Pseudomonas aeruginosa), and a parasite (Cryptosporidium parvum). We have previously reported that androstenediol (5-androstene-3 beta, 17 beta-diol, AED), derived from DHEA, is at least 100 x more effective in up-regulating systemic resistance against CB4 infection than its precursor. Furthermore, androstenetriol (5-androstene-3 beta,7 beta, 17 beta-triol, AET) which is formed by 7 beta hydroxylation of AED, was more effective against CB4 infection than its precursor, AED. Neither steroid, however, has shown any significant direct antiviral effects. The in vitro influences of DHEA, AED and AET on a mitogen-induced mixed splenocyte proliferation assay were determined. The results showed that DHEA suppressed the proliferation of concanavalin A (ConA)- or lipopolysaccharide-activated cultures in a dose-dependent manner. AED had little influence on the activation response. However, AET potentiated the response to both mitogens significantly above the control level. The regulation of interleukin (IL)-2 and IL-3 secretion from ConA-activated lymphocytes was analogous to these observations. These functions were depressed by DHEA, unaffected by AED, and potently increased by AET. Moreover, the classic immunosuppressive effects of hydrocortisone on ConA-induced lymphocyte proliferation, as well as IL-2 and IL-3 production, were unaffected by co-culture with DHEA and only minimally counteracted by AED. In contrast. AET significantly counteracted the effect of hydrocortisone when co-cultured together. These data show that while DHEA, AED and AET each function in a similar manner in vivo, in vitro their effects are dramatically different from one another with only AET potentiating the cellular response by increasing lymphocyte activation and counteracting the immunosuppressive activity of hydrocortisone.

In vitro potentiation of lymphocyte activation by dehydroepiandrosterone, androstenediol, and androstenetriol

Dehydroepiandrosterone (5-androstene-3 beta-ol-17-one, DHEA) has been shown to protect mice from lethal viral and bacterial infections. However, recently, androstenediol (5-androstene-3 beta-17 beta-diol, AED) and androstenetriol (5-androstene-3 beta-7 beta-triol, AET), metabolites of DHEA, have each shown to be more potent endocrine regulators of the immune response. In contrast to glucocorticosteroids, in vivo, these steroid hormones up-regulated the cellular immune response of the host to limit virus-mediated pathology. These experiments first examined the in vitro influences of DHEA, and AED, or AET on mitogen-stimulated activation of murine lymphocytes. From physiologic to pharmacologic doses, DHEA suppressed proliferation of mixed splenocyte cultures activated with Con A or LPS by 20 to 70% whereas AED had little influence on the response. In sharp contrast, AET potentiated the response with both mitogens to 50 to 70% above control. Analogous to these observations was the regulation of IL-2 and IL-3 secretion from Con A-activated lymphocytes by each of these hormones which again was depressed analyzed. The suppressive effects of hydrocortisone on Con A-induced lymphocyte proliferation and cytokine production were strongly counteracted by coculture with AET. DHEA did not counteract hydrocortisone activity whereas AED showed moderate antiglucocorticoid function.

In vitro potentiation of lymphocyte activation by dehydroepiandrosterone, androstenediol, and androstenetriol

Dehydroepiandrosterone (5-androstene-3 beta-ol-17-one, DHEA) has been shown to protect mice from lethal viral and bacterial infections. However, recently, androstenediol (5-androstene-3 beta-17 beta-diol, AED) and androstenetriol (5-androstene-3 beta-7 beta-triol, AET), metabolites of DHEA, have each shown to be more potent endocrine regulators of the immune response. In contrast to glucocorticosteroids, in vivo, these steroid hormones up-regulated the cellular immune response of the host to limit virus-mediated pathology. These experiments first examined the in vitro influences of DHEA, and AED, or AET on mitogen-stimulated activation of murine lymphocytes. From physiologic to pharmacologic doses, DHEA suppressed proliferation of mixed splenocyte cultures activated with Con A or LPS by 20 to 70% whereas AED had little influence on the response. In sharp contrast, AET potentiated the response with both mitogens to 50 to 70% above control. Analogous to these observations was the regulation of IL-2 and IL-3 secretion from Con A-activated lymphocytes by each of these hormones which again was depressed analyzed. The suppressive effects of hydrocortisone on Con A-induced lymphocyte proliferation and cytokine production were strongly counteracted by coculture with AET. DHEA did not counteract hydrocortisone activity whereas AED showed moderate antiglucocorticoid function.

Mobilization of cutaneous immunity for systemic protection against infections

This laboratory reported that a single subcutaneous (SC) injection of the natural steroid hormone dehydroepiandrosterone (DHEA) resulted in significant protection against a lethal herpes virus type 2 encephalitis or a systemic coxsackievirus B4 infection. Our previous results have shown that SC injection of DHEA resulted in upregulation of the specific host immune response resulting in protection against a lethal infection. This hormone did not have any direct antiviral effects in vitro. Furthermore, results indicate that, in vivo, DHEA is not the agent directly mediating the upregulation of the immune response. In the skin, DHEA is converted to androstenediol (AED) and it, in turn, is converted to androstenetriol; this is a metabolic process which appears unique to the skin. This report demonstrates that SC injection of AED results in markedly greater resistance against both viral and bacterial infection. Both DHEA and AED appear to function by facilitating and upregulating host immune responses via mobilization of cutaneous immunity to obtain systemic protection against infections. Because these steroids are native to the host and are regulated by the central nervous system, it is suggested that they may be an integral element of neuroimmunomodulation.

Androstenediol regulates systemic resistance against lethal infections in mice

We previously reported that subcutaneous injection of DHEA (5-androsten-3 beta-ol-17-one, dehydroepiandrosterone) protected mice from lethal infection. This included both a lethal herpes virus type 2 encephalitis and a lethal systemic coxsackievirus B4 (CB4) infection. Androstenediol (5-androsten-3 beta-17 beta-diol, AED), a metabolic product of DHEA is up to 100 x more effective in regulating systemic resistance against lethal infection with CB 4 than its precursor DHEA. Compared to DHEA, treatment with AED was markedly superior in protecting mice against virus induced myocardiopathy, pancreopathy, and mortality. In addition to its protective effect, AED but not DHEA, induced a 3-4 fold proliferation of the spleen and thymus in virus infected animals; this effect of AED was only seen above a certain threshold dose. Neither steroid, however, has shown any significant direct antiviral effect in vitro; similarly, virus tissues titers in vivo are not affected by the hormones. Additionally, both DHEA and AED protected against a lethal infection with Enterococcus faecalis. These observations demonstrate that the steroid hormones DHEA and AED provide a novel approach for prevention and protection of the host from a variety of infectious diseases.

Clinical variation in X-linked adrenoleukodystrophy: fatty acid and lipid metabolism in cultured fibroblasts

To determine whether the clinical phenotype of ALD correlates with the extent of metabolic abnormality, we investigated VLFA metabolism in cultured fibroblasts from patients with the clinically severe childhood from of ALD and the milder AMN variant. No differences were seen in the content of neutral lipids or phospholipids, in incorporation of [1-14C]lignocerate into cellular lipids, or in the fatty acid composition of fibroblasts from patients with childhood ALD or AMN. [1-14C]Lignocerate oxidation was deficient to a similar extent (35-40% of normal) in both intact fibroblasts and cell homogenates from patients with childhood ALD and AMN. With the use of fibroblast homogenates, oxidation of lignocerate was partially inhibited by various long-chain fatty acids, and residual activity in ALD homogenates was more susceptible to inhibition by palmitate than normal. In the presence of competing palmitate, residual lignocerate oxidative activity in fibroblast homogenates was reduced to 20 +/- 4% of normal in childhood ALD and 24 +/- 2% of normal in AMN. These results indicate that residual VLFA oxidative activity, fatty acid composition, VLFA metabolism, and lipid content of cultured fibroblasts do not correlate with the clinical expression of the ALD gene.

Immunodeficiency as primary phenotype of diabetes mutation db. Studies with coxsackievirus B4

Restriction of food intake (R) in the C57BL/KsJ db/db diabetic mutant mouse prevents phenotypic expression of diabetes, whereas ad libitum feeding (AL) results in spontaneous diabetes. Previous results showed that coxsackievirus B4 (CB4)-infected genetically identical db/db mice with and without diabetes could be distinguished by the levels of CB4-neutralizing antibody and virus-specific antibodies as determined by enzyme-linked immunosorbent assay and the numbers of splenic antibody-forming cells. Our results show that the diabetic genotype db/db R was deficient in total spleen lymphocytes and lymphocyte subsets and was unable to produce agglutinating antibody to sheep erythrocytes (SRBCs) or specific antibody to noninfectious CB4. The db/db AL mutant expressing the diabetic phenotype was not as deficient in spleen cell parameters. The response to noninfectious CB4 was delayed but substantial. The db/db AL mouse was also unique with its higher agglutinating antibody levels after virus infection than its uninfected control or the infected or uninfected db/db R mouse. In vitro SRBC immunization of spleen lymphocytes determined that this enhanced response was largely dependent on the diabetic milieu and was not a property of the cells. Genetic predisposition to diabetes is characterized by immunodeficiency as evident from inadequate levels of antibodies to infectious or noninfectious antigens and absolute and relative deficiency in spleen lymphocyte subsets and total numbers of spleen cells. Phenotypic expression of diabetes results in partial amelioration of the immunodeficiency evident in diabetic genotype db/db R without disease.

Evaluation of virus neutralization antibody levels in diabetic mutant mice

Experiments were designed to determine whether genetic predisposition to diabetes or overt diabetes in the identical genotype had an effect on the level of neutralization antibodies to coxsackievirus B4 (CB4). Quantitation of neutralization antibody (NT) levels against CB4 was performed using both the 50% endpoint procedure and the multivariate Wilcoxon rank sum test. The results of these experiments demonstrate that the use of the multivariate procedure for the analysis of neutralization antibody levels provides both quantitative and qualitative information not evident when only the classical 50% end point procedure is used. Moreover, when comparison on antibody levels between different groups is being considered, the power of the comparison is markedly greater using the multivariate Wilcoxon rank sum test results. The present report provide an illustration of the difference in the qualitative and quantitative information obtained by the end-point procedure and the more comprehensive multivariate procedure for the analysis of neutralization antibody levels in diabetic mutant mice infected with coxsackievirus B4.

Protection against acute lethal viral infections with the native steroid dehydroepiandrosterone (DHEA)

A significant protective effect of a native adrenal steroid, dehydroepiandrosterone (DHEA), was demonstrated in studies of two lethal viral infection models in mice: systemic coxsackievirus B4 and herpes simplex type 2 encephalitis. The steroid was active either by long-term feeding or by a single subcutaneous injection. A closely related steroid, etiocholanolone, was not protective in these models. Histopathological analysis, leukocyte counts, and numbers of spleen antibody forming cells in the coxsackievirus B4 model suggests that DHEA functions by maintaining or potentiating the immune competence of mice otherwise depressed by viral infection. DHEA was not effective in genetically immunodeficient HRS/J hr/hr mice and did not demonstrate antiviral activity in vitro. While the molecular basis for DHEA's effect on the immune system is not known, studies by others suggest that it may counteract the stress related immunosuppressive effects of glucocorticoids stimulated by viral infection. Because DHEA is a native steroid that has been used clinically with minimal side effects, the utility of DHEA in the therapeutic modulation of acute and chronic viral infections including the acquired immune deficiency syndrome deserves intensive study.

Humoral immune response in hereditary and overt diabetes mellitus

The inbred diabetic mutant mouse, C57BL/KsJ db +/db + (db +/db +), spontaneously develops diabetes mellitus when allowed food ad libitum. However, restriction of food intake prevents the expression of this genetic predisposition for diabetes. This experimental design has been used previously to demonstrate a deficient neutralizing antibody response to coxsackievirus B4 (CB4) in mutants with the genetic predisposition only. These observations demonstrate that in the genetically predisposed diabetic mutant, deficient humoral immunity extends further to a general impairment in both total IgM and IgG production after CB4 infection. Furthermore, these mice are unable to produce a virus-specific IgG response but do show a high level of nonspecific antibody suggesting a polyclonal activation following CB4 challenge. In addition, we observed an increase in the number of spleen IgM antibody-forming cells to sheep erythrocytes (SRBC) in the overtly diabetic animal following CB4 infection with little change apparent in the genetically predisposed animal after infection. These results were identical to the changes seen in total spleen cell numbers. Our animal model provides an opportunity to distinguish between the genetic predisposition to diabetes and the overt disease and suggests that some of the immune impairment found prior to diabetes onset may be partially diminished afterwards.

Genetic predisposition to diabetes mellitus is associated with impaired humoral immunity to coxsackievirus B4

Experiments were performed to determine whether genetic predisposition to diabetes mellitus (DM) or clinical DM or both exert an influence on the production of neutralization antibodies to coxsackievirus B4 (CB4). The homozygous diabetic mutant mouse db+/db+, on the inbred C57BL/KsJ genetic background, develops a diabetes-like disease when maintained on ad libitum diet but restriction of excess food intake prevents overt disease. The doubly heterozygote db+/+m or the homozygote +m/+m misty coat color mutant, on the C57BL/KsJ genetic background, do not develop DM and served as controls. Animals infected with one-half a previously determined LD50 of CB4 were bled prior to infection and at 3, 5, 7, 14, 21 days and at 1, 2, 3, 4 and 5 months after infection. Serum neutralization antibody (NA) levels were determined from the percent CB4 plaque reduction. Until 2 months following infection, NA levels were not significant in either of the homozygous diabetic mutant groups, db+/db+. In the diabetic mutant group db+/db+, without overt disease, neutralization of CB4 when observed, was low, short-lived, and apparently not specific. However, in the homozygous diabetic mutants with spontaneous diabetes, CB4 NA became evident at 2 months after infection. By 3 months post-infection, serum NA levels were sufficient to cause 90% virus plaque reduction. These observations demonstrate that hereditary DM as characterized by the mutation diabetes, db, in the C57BL/KsJ mouse, is associated with a marked impaired humoral immune response to a diabetogenic human CB4. Specifically, there is an inability to develop an adequate level of anti-CB4 antibodies. The type and degree of immunological impairment are apparently different prior to and after onset of diabetes mellitus.

Influence of genetic predisposition to diabetes and obesity on mitochondrial function

Inbred mice with the mutation diabetes C57BL/KsJ db+/db+ and the mutation obese C57BL/6J ob/ob displayed a total liver mitochondrial capacity to oxidize glutamate or succinate which was approximately eight times greater than the capacity of the C57BL/6J +/+ control mice. This increase in oxidation capacity was estimated by multiplying the observed twofold increase in each of the following components: total liver weight, the mitochondrial protein content per gram of liver, and glutamate or succinate respiration activity per milligram of liver mitochondrial protein. No significant difference in liver mitochondrial function and capacity for oxidation was observed between db+/db+ and ob/ob mutants, which indicated that these results may be primarily mediated by the genetic factors responsible for obesity and hyperphagia in these mutants, and not by the genetic traits associated with diabetes. These findings may provide a biochemical foundation in support of the thrifty gene hypothesis.

Influence of diabetes mellitus heredity on susceptibility to coxsackievirus B4

Using the criteria of virus susceptibility as defined by the 50 percent lethal dose response and the percent cumulative mortality response it was shown that the diabetic mutation db, located on chromosome 4, exerted a particular influence on the host response to CB4 challenge. Neither the yellow obese mutation Ay on chromosome 2 nor the misty coat color mutation located one centimorgan from the db mutation had the same effect on CB4 response. The obese diabetic mutation ob located on chromosome 6 appeared to enhance susceptibility to CB4. However, the high susceptibility of the inbred C57BL/6J line on which the ob mutation is found was apparently a significant contributing factor to the ob mutant high virus susceptibility. The response to CB4 was also a useful criteria to discern differences in the genetic background of closely related inbred lines. Based on the CB4 LD50 values the C57BL/6J inbred line was the most susceptible while the C57BL/Ks inbred line was the most resistant. However, using the percent cumulative mortality response as an index of host resistance, the C57BL/KsJ was the most susceptible and the C57BL/Ks the least. These findings further support the thesis that genetic predisposition to diabetes mellitus, as characterized by the mutation db on chromosome 4 is associated with a particular susceptibility and host response to coxsackie-virus B4. It also illustrates that under specific conditions, comparison of the response to virus challenge can be used as an indicator of genetic differences between closely related inbred lines.

Dietary hepatic cholesterol elevation: effects on coxsackievirus B infection and inflammation

Mice made hypercholesterolemic (HC) by diet are highly susceptible to coxsackievirus (CV) B5, whereas normal adult animals remain resistant. In attempting to define those dietary-induced physiological changes which contribute to altered resistance, a strong association between accumulation of intrahepatic cholesterol and increased CV B5-induced mortality was demonstrated, with maximum susceptibility to CV coinciding with a 2.5-fold increase in the ratio of hepatic cholesterol to protein. This metabolic imbalance was associated with a lower clearance rate of CV from the blood and liver of C57BL/6 mice, although virus-specific neutralizing antibody production was unaltered. In addition to CV, HC mice were more susceptible to an intravenous inoculation of Listeria monocytogenes in comparison to controls. The macrophage stimulant Corynebacterium parvum failed to increase resistance of HC mice to a high dose of CV B4 and L. monocytogenes and failed to induce the hepatomegaly, splenomegaly, and cellular infiltrate seen in the liver and spleen of normal animals. Furthermore, the peritoneal monocytic infiltrate induced by thioglycolate in normal animals was absent in HC mice. Results from these experiments suggest that decreased resistance to CV in the HC host is attributed to a defect in the nonspecific immune responses of macrophages and monocytes which are of primary importance in resistance to this virus and other infectious agents.

Host factors in Coxsackievirus B4-induced pancreopathy

The diabetogenic potential of the human isolate, Coxsackievirus B4 (CB4) (Edwards) was studied in three inbred mice strains, SWR/J, DBA/2, and C57BL/6. The mice were infected with this agent and evaluated for mortality, pancreatic histopathology, and glucose tolerance. Results showed that the mortality induced by CB4 in these inbred strains differed considerably. There was no evidence of a correlation between virus-induced mortality and virus-induced pancreopathy. Although CB4 (Edwards) was most lethal to C57BL/6 mice, based on the infecting 50 per cent lethal dose (LD50), this mouse strain developed no pancreatic pathology. The most severe pancreopathy, i.e., acinar necrosis with acute interstitial inflammation and islet atrophy, was observed in SWR/J mice, which had an intermediate susceptibility to virus-induced mortality. DBA/2 mice, which displayed the lowest susceptibility to virus-induced lethality, showed less pancreatic pathology (i.e., acute and chronic interstitial inflammation) than SWR/J mice. IN SWR/J mice, virus-mediated alteration in glucose homeostasis was expressed by an increase in glucose tolerance 7 and 21 days after infection. In contrast, C57BL/6 mice showed a tendency toward chemical diabetes at 21 days postinfection. This study suggests that CB4-induced mortality and pancreatic pathology are independent parameters and do not necessarily determine the glucose tolerance of a given host genotype.

Proaggregatory effect of fasting on platelet aggregation in the microcirculation of mice with streptozotocin diabetes

This study investigates whether experimental diabetes alters the ease with which platelet aggregation can be initiated in pial and mesenteric microvessels of the mouse. Aggregation was elicited by exposing microvessels to radiant energy from a mercury lamp in the presence of sodium fluorescein. The time required for this noxious stimulus to initiate aggregation was similar in fed or fasted alloxan diabetics and their controls, and in fed streptozotocin diabetics and their controls, but was significantly shortened in streptozotocin mice fasted for 18 to 24 hours when these animals were compared with either fed or fasted controls. Aggregation was also elicited by puncture of microvessels or by micropunture plus locally applied adenosine 5'-diphosphate. No differences in aggregability were found between either fed or fasted diabetics and their respective controls. In the light plus dye model of injury, the capacity to enhance aggregation at will by fasting streptozotocin diabetics may provide a means by which some of the factors controlling aggregation in this model of diabetes can be identified, enhanced aggregation in other species or in other types of diabetes.

Platelet aggregation in the cerebral and mesenteric microcirculation of mice with genetically determined diabetes

Platelet aggregates were induced in pial arterioles of the following strains of mice with a genetic predisposition for diabetes: ob/ob and db+/db+. Aggregation was compared with that in 6J+/+ mice, the nondiabetic controls for ob/ob animals, and in +m/+m as well as db+/+m, the nondiabetic controls for db+/db+ mice. Aggregation was also induced within mesenteric arterioles of db+/db+ animals and compared with that in db+/+m mice. Aggregation was monitored microscopically, by measuring the time required for a noxious stimulus to initiate aggregation in an injured arteriole. Platelet aggregation was initiated with equal ease in the pial arterioles of ob/ob mice and their 6J+/+ controls. However, the onset of aggregation in the pial arterioles of the db+/db+ group was significantly delayed when compared with the onset in either of the nondiabetic control groups, +m/+m or db+/+m. A similar prolongation in the time required to produce aggregation was also observed in the mesenteric arterioles of the db+/db+ mice when compared with db+/+m controls. The basis for reduced platelet aggregation in the microcirculation of db+/db+ mice is not explained. The results differ from those showing enhanced aggregation in many in vitro studies of platelets from human diabetics and from those of in vivo studies of two other animal models described in the literature. However, not all published studies have reported enhanced aggregation. The delayed aggregation in the present study may provide a basis for analysis of factors that regulate platelet aggregation in diabetes.

Inhibition of host resistance by nutritional hypercholesteremia

Previous experiments showed that nutritionally induced hypercholesteremia in mice caused an increase in susceptibility to coxsackievirus B, with a marked suppression of cellular infiltrates in infected tissues and an increased mortality. The present studies demonstrated that a hypercholesteremic diet was associated with an inhibition in host resistance as measured by susceptibility to Listeria monocytogenes infection and the growth of two transplanted syngeneic murine tumors. Moreover, the ability of Corynebacterium parvum to induce regression of a transplanted methylcholanthrene-induced fibrosarcoma was inhibited in hypercholesteremic hosts, as was the histiocytic infiltration normally accompanying C. parvum inoculation. In contrast, the peritoneal macrophages from C. parvum-treated hypercholesteremic mice were indistinguishable from similarly treated macrophages from normal mice with respect to their in vitro tumoricidal activity and the presence of a cell surface antigen associated with activated macrophages. Hypercholesteremia was also associated with a decreased antibody response to sheep erythrocytes in vivo, but dit not appear to exert a detrimental effect on B- or T-cell blastogenesis when tested in vitro. The findings that the hypercholesteremic diet was associated with an impairment in the host immune response and increased susceptibility to viral, bacterial, and tumor cell challenge are discussed with respect to virus-lipid interactions in the pathogenesis of atherogenesis and diabetes mellitus.

Suppression of aortic elastic tissue autofluorescence for the detection of viral antigen

Suppression of aortic elastic tissue autofluorescence was achieved by employing a modification of Verhoeff's elastic tissue staining procedure. Consquently, coxsackievirus B antigen present in the aortic media was detected by conventional fluorescent antibody staining.

Migration of epithelial cells in the small intestine of mice perorally infected with coxsackievirus B5

The rate of cell migration in the small intestine during enteric viral infections has not been assessed previously. CD-1 mice (33 days old) were infected perorally with 1.0 X 10(8) plague-forming units of coxsackievirus B5 and 12 hr later were injected intraperitoneally with 2 micron Ci of [3H]thymidine/g of body weight. After 2, 12, 24, 48, 60, and 72 hr, mice were killed, and the small intestine was removed. Specimens obtained at each interval were examined by radioautography; similar specimens were titrated for virus by plaque assay in HeLa cells. In mice perorally infected with coxsackievirus B5, epithelial cells migrated from crypt to villus tip in 60 hr, as compared with 48 hr in uninfected control mice and 24 hr previously reported for mice perorally infected with enteric bacteria (e.g., Salmonella typhimurium). Virus was recovered from intestinal tissue, but no inflammatory response in the limina propria was apparent. These observations are consistent with previous report that substrate absorption rates may be altered during viral and bacterial enteric infection.

Coxsackievirus B cardiopathy and angiopathy in the hypercholesterolemic host

Studies on the pathogenic potential of the human cardiotropic enterovirus, coxsackievirus B5, show that this agent localizes and replicates in the aorta of mice. Nutritionally-induced hypercholesterolemia leads to an increased replication and persistence of virus in tissues, specifically the aorta. Coxsackievirus B cardiopathy is markedly augmented in the hypercholesterolemic host, resulting in a persistent cardiomyolysis which is not evident in virus-infected animals with normal cholesterol levels. Pathological changes in the aorta become evident only months after the acute infection, and only in hypercholesterolemic animals previously infected with coxsackievirus B5. Our findings of coxsackievirus B-induced angiopathy and cardiopathy in the hypercholesterolemic host extend the known pathogenic range of these human viruses, and further emphasizes their potential as etiological agents of cardiovascular disease.

Pathophysiological aspects of coxsackievirus B intestinal infection

Our findings reveal that intestinal infection with coxsackie B5 results in decreased intestinal epithelial cell division in association with an increase in carbohydrate (glucose) and amino acid (leucine) absorption in the small intestine. These findings are contrasted with those occurring during Salmonella infection, which results in increased intestinal cell division rate but decreased carbohydrate (glucose) absorption. The changes in intestinal function and physiology that have been described occurred during an asymptomatic viral infection characterized by normal intestinal histology. A reasonable hypothesis is that these pathophysiological changes may be due not only to a variety of local factors but also to hormonal effects induced by systemic spread of coxsackievirus B.

Measurement of intestinal absorption in mice by a double-label radioisotope perfusion technic

The use of the standard chemical technic for measuring intestinal glucose absorption was compared with a new double-label radioisotope technic. Glucose absorption and water flux in the mouse small intestine were measured by both methods. The results indicated that the 2 approaches yield almost identical values. The radioisotope technic utilized [14C] polyethylene glycol to measure water flux and [3H] glucose. The technic was found to be reliable, rapid, and applicable to small samples and other substrates. It is particularly suited to absorption studies in small animals such as the mouse, where sample size is limited. The study also showed that the polyethylene glycol recovery rate from the mouse intestine was 97.8%, indicating that it is a valid absorption marker in this species.

Infection of hypercholesterolemic mice with Coxsackievirus B

Adult male mice were made hypercholesterolemic by a diet high in cholesterol, cholic acid, animal fat, and sucrose. After three months on this diet, animals were infected with 5 X 10(9) plaque-forming units of coxsackievirus B5. Control groups consisted of uninfected hypercholesterolemic mice and infected mice maintained on a standard laboratory diet. Infection in the hypercholesterolemic animals was associated with leukopenia, severe fatty metamorphosis and focal necrosis in the liver, cholelithiasis, ileus, cardiomyolysis, and lack of inflammatory response. These mice died within seven to 14 days. Uninfected hypercholesterolemic animals had lesser degrees of fatty liver and cholelithiasis, and all survived. Infected mice maintained on a standard diet also survived. Titers of virus in representative tissues were lower in the hypercholesterolemic than in the normal mice, an indication that replication of virus was not solely responsible for the lethal outcome of the infections. These experiments demonstrate that hypercholesterolemia may alter host defenses against group B coxsackievirus in the mouse.

Maturation of intestinal defenses against peroral infection with group B coxsackievirus in mice

The intestinal tract of adult mice provides effective protection against peroral infection with group B coxsackievirus. This protective function consists of at least two separate components. One is a barrier effect that prevents virus from passing through the mucosal side of the gut into the circulation. It becomes clearly evident at 18 days of life and is present thereafter. The other is a clearance mechanism that acts to eliminate virus from the enteric tract after infection has occurred. This is first demonstrable at about 14 to 18 days and also persists. The appearance of these protective functions coincides with the known development of enzymatic and morphological changes in the gut associated with the transition from suckling to weanling.

Susceptibility of mice to group B coxsackie virus is influenced by the diabetic gene

A positive correlation was found between genetic predisposition to diabetes in the mouse and susceptibility to group B Coxsackie virus in this host. Male mice of the inbred strain C57BL/Ks and the following genetic variants were used; mice homozygous for the autosomal recessive gene for diabetes (db/db), the phenotypically normal heterozygous (db/+), and the normal mice which lacked the diabetic gene (+/+). The mortality response of the +/+ mice to intraperitoneal inoculation with Coxsackie virus B4 differed from the response of the two genetic variants (db/db and db/+) derived from this strain. The db/+ variant was more susceptible to Coxsackie virus B4 than the parental background strain (+/+). The db/db variant was more susceptible than either of the other genotypes. Pathological findings of the pancreas of the three genotypes during the acute stage of infection closely paralleled the genotypically dependent susceptibility of the host.