Dexamethasone and mifepristone increase retroviral infectivity through different mechanisms

Non-Targeted Metabolomic Analysis of Chicken Kidneys in Response to Coronavirus IBV Infection Under Stress Induced by Dexamethasone

Stress in poultry can lead to changes in body metabolism and immunity, which can increase susceptibility to infectious diseases. However, knowledge regarding chicken responses to viral infection under stress is limited. Dexamethasone (Dex) is a synthetic glucocorticoid similar to that secreted by animals under stress conditions, and has been widely used to induce stress in chickens. Herein, we established a stress model in 7-day-old chickens injected with Dex to elucidate the effects of stress on IBV replication in the kidneys. The metabolic changes, immune status and growth of the chickens under stress conditions were comprehensively evaluated. Furthermore, the metabolic profile, weight gain, viral load, serum cholesterol levels, cytokines and peripheral blood lymphocyte ratio were compared in chickens treated with Dex and infected with IBV. An LC-MS/MS-based metabolomics method was used to examine differentially enriched metabolites in the kidneys. A total of 113 metabolites whose abundance was altered after Dex treatment were identified, most of which were lipids and lipid-like molecules. The principal metabolic alterations in chicken kidneys caused by IBV infection included fatty acid, valine, leucine and isoleucine metabolism. Dex treatment before and after IBV infection mainly affected the host’s tryptophan, phenylalanine, amino sugar and nucleotide sugar metabolism. In addition, Dex led to up-regulation of serum cholesterol levels and renal viral load in chickens, and to the inhibition of weight gain, peripheral blood lymphocytes and IL-6 production. We also confirmed that the exogenous cholesterol in DF-1 cells promoted the replication of IBV. However, whether the increase in viral load in kidney tissue is associated with the up-regulation of cholesterol levels induced by Dex must be demonstrated in future experiments. In conclusion, chick growth and immune function were significantly inhibited by Dex. Host cholesterol metabolism and the response to IBV infection are regulated by Dex. This study provides valuable insights into the molecular regulatory mechanisms in poultry stress, and should support further research on the intrinsic link between cholesterol metabolism and IBV replication under stress conditions.

Dexamethasone treatment decreases replication of viral hemorrhagic septicemia virus in Epithelioma papulosum cyprini cells

The expression of Mx1 in EPC cells after treatment with poly(I:C) or infection with viral hemorrhagic septicemia virus (VHSV) was significantly suppressed by treatment with dexamethasone. However, the titer of VHSV did not increase but instead decreased after dexamethasone treatment. This suggests that dexamethasone not only downregulates type I IFN but also affects certain factors that are necessary for VHSV replication. An important effect of HSP90 on replication of RNA viruses and downregulation of HSP90 by glucocorticoids have been reported. In this study, dexamethasone downregulated HSP90α expression in EPC cells that were stimulated with poly(I:C) or infected with VHSV. Furthermore, cells treated with an HSP90 inhibitor, geldanamycin, showed significantly decreased titers of VHSV, suggesting that HSP90 may be an important host component involved in VHSV replication, and HSP90 inhibition might be one of the causes for the observed reduction in viral titer caused by dexamethasone treatment.

Simple viral/minimal piggyBac hybrid vectors for stable production of self-inactivating gamma-retroviruses

Background

Transient production of gamma-retroviruses, including self-inactivating (SIN) retroviruses, is a common method for rapidly generating virus capable of gene delivery. Stable (continuous) production of virus is preferable to transient production for clinical and biotechnology purposes, however, because it allows for significant quantities of a uniform virus to be generated over a prolonged period of time, thus allowing for longitudinal functional studies and quality analysis. Unfortunately, stable production of SIN retroviruses is difficult to achieve.

Results

We describe a novel method to rapidly and cost-effectively create packaging cells capable of continuously producing self-inactivating gamma-retroviruses. We imbedded the SIN proviral construct into a minimal piggyBac transposon vector and then integrated the hybrid vector into packaging cells that already stably expressed the viral gag-pro-pol and envelope genes. Cells that stably produced self-inactivating gamma-retroviruses could be identified (and purified) as early as 3 weeks after initial transfection; these cells produced virus for at least 9 weeks without a decline in titer.

Conclusions

This viral-minimal piggyBac hybrid vector allowed for the rapid generation and purification of packaging cells capable of stably producing self-inactivated gamma-retroviruses. This method can be applied to the large-scale production of viruses for use in research, biotechnology, and potentially, clinical trials.

Is Dysregulation of the HPA-Axis a Core Pathophysiology Mediating Co-Morbid Depression in Neurodegenerative Diseases?

There is increasing evidence of prodromal manifestation of neuropsychiatric symptoms in a variety of neurodegenerative diseases such as Parkinson's disease (PD) and Huntington's disease (HD). These affective symptoms may be observed many years before the core diagnostic symptoms of the neurological condition. It is becoming more apparent that depression is a significant modifying factor of the trajectory of disease progression and even treatment outcomes. It is therefore crucial that we understand the potential pathophysiologies related to the primary condition, which could contribute to the development of depression. The hypothalamic-pituitary-adrenal (HPA)-axis is a key neuroendocrine signaling system involved in physiological homeostasis and stress response. Disturbances of this system lead to severe hormonal imbalances, and the majority of such patients also present with behavioral deficits and/or mood disorders. Dysregulation of the HPA-axis is also strongly implicated in the pathology of major depressive disorder. Consistent with this, antidepressant drugs, such as the selective serotonin reuptake inhibitors have been shown to alter HPA-axis activity. In this review, we will summarize the current state of knowledge regarding HPA-axis pathology in Alzheimer's, PD and HD, differentiating between prodromal and later stages of disease progression when evidence is available. Both clinical and preclinical evidence will be examined, but we highlight animal model studies as being particularly useful for uncovering novel mechanisms of pathology related to co-morbid mood disorders. Finally, we purpose utilizing the preclinical evidence to better inform prospective, intervention studies.

Corticotropin-releasing hormone receptor-1 and 2 activity produces divergent resistance against stress-induced pulmonary Streptococcus pneumoniae infection

Utilizing a murine model of S. pneumoniae infection and restraint stress, we determined how corticotropin releasing hormone (CRH-R) receptors impacts disease. CRH-R1 (antalarmin) and CRH-R2 (astressin2B) antagonists were administered intraperitoneally prior to restraint stress followed by pulmonary S. pneumoniae infection. CRH-R1 inhibition is not protective against pneumococcal disease induced by stress. Conversely, CRH-R2 inhibition attenuates stress-induced bacterial growth and significantly prevented severe sepsis. Neutrophillic responses were associated with CRH receptor-specific disease outcome providing a potential cellular target for stress-induced susceptibility to the development of severe pneumococcal disease. CRH receptor-mediated effects on immune responses could prove valuable for novel therapeutics.

The Neural/Immune Gene Ontology: clipping the Gene Ontology for neurological and immunological systems

BACKGROUND

The Gene Ontology (GO) is used to describe genes and gene products from many organisms. When used for functional annotation of microarray data, GO is often slimmed by editing so that only higher level terms remain. This practice is designed to improve the summarizing of experimental results by grouping high level terms and the statistical power of GO term enrichment analysis. Here, we propose a new approach to editing the gene ontology, clipping, which is the editing of GO according to biological relevance. Creation of a GO subset by clipping is achieved by removing terms (from all hierarchal levels) if they are not functionally relevant to a given domain of interest. Terms that are located in levels higher to relevant terms are kept, thus, biologically irrelevant terms are only removed if they are not parental to terms that are relevant.

RESULTS

Using this approach, we have created the Neural-Immune Gene Ontology (NIGO) subset of GO directed for neurological and immunological systems. We tested the performance of NIGO in extracting knowledge from microarray experiments by conducting functional analysis and comparing the results to those obtained using the full GO and a generic GO slim. NIGO not only improved the statistical scores given to relevant terms, but was also able to retrieve functionally relevant terms that did not pass statistical cutoffs when using the full GO or the slim subset.

CONCLUSIONS

Our results validate the pipeline used to generate NIGO, suggesting it is indeed enriched with terms that are specific to the neural/immune domains. The results suggest that NIGO can enhance the analysis of microarray experiments involving neural and/or immune related systems. They also directly demonstrate the potential such a domain-specific GO has in generating meaningful hypotheses.

Mifepristone increases gamma-retroviral infection efficiency by enhancing the integration of virus into the genome of infected cells

Gamma-retroviruses are commonly used to deliver genes to cells. Previously, we demonstrated that the synthetic anti-glucocorticoid and anti-progestin agent, mifepristone, increased gamma-retroviral infection efficiency in different target cells, independent of viral titer. In this study, we examine how this occurs. We studied the effect of mifepristone on different steps of viral infection (viral entry, viral survival, viral DNA synthesis and retrovirus integration into the host genome) in three distinct retroviral backbones using different virus recognition receptors. We also tested the potential role of glucocorticoid and progesterone receptors in mediating mifepristone's ability to increase gamma-retroviral infectivity. We show that mifepristone increases gamma-retroviral infection efficiency by facilitating viral integration into the host genome and that this effect seems to be due to mifepristone's anti-glucocorticoid, but not its anti-progestin, activity. These results suggest that inhibition of the glucocorticoid receptor enhances retroviral integration into the host genome and indicates that cells may have a natural protection again retroviral infection that may be reduced by glucocorticoid receptor antagonists.