Diazepam-mediated inhibition of human immunodeficiency virus type 1 expression in human brain cells

Neuronal and Non-Neuronal GABA in COVID-19: Relevance for Psychiatry

Infection with SARS-CoV-2, the causative agent of the COVID-19 pandemic, originated in China and quickly spread across the globe. Despite tremendous economic and healthcare devastation, research on this virus has contributed to a better understanding of numerous molecular pathways, including those involving γ-aminobutyric acid (GABA), that will positively impact medical science, including neuropsychiatry, in the post-pandemic era. SARS-CoV-2 primarily enters the host cells through the renin–angiotensin system’s component named angiotensin-converting enzyme-2 (ACE-2). Among its many functions, this protein upregulates GABA, protecting not only the central nervous system but also the endothelia, the pancreas, and the gut microbiota. SARS-CoV-2 binding to ACE-2 usurps the neuronal and non-neuronal GABAergic systems, contributing to the high comorbidity of neuropsychiatric illness with gut dysbiosis and endothelial and metabolic dysfunctions. In this perspective article, we take a closer look at the pathology emerging from the viral hijacking of non-neuronal GABA and summarize potential interventions for restoring these systems.

Repurposing Psychotropic Agents for Viral Disorders: Beyond Covid

Recent reports have highlighted the possible role of the antipsychotic chlorpromazine and the antidepressant fluvoxamine as anti-coronavirus disease 2019 (COVID-19) agents. The objective of this narrative review is to explore what is known about the activity of psychotropic medications against viruses in addition to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). PubMed was queried for "drug repurposing, antiviral activity," and for "antiviral activity" with "psychotropic drugs" and individual agents, through November 2020. Of more than 100 psychotropic agents, 37 drugs, including 27 with a history of pediatric use were identified, which had been studied in the preclinical setting and found to have activity against viruses which are human pathogens. Effects were evaluated by type of virus and by category of psychotropic agent. Activity was identified both against viruses known to cause epidemics such as SARS-CoV-2 and Ebola and against those that are the cause of rare disorders such as Human Papillomatosis Virus-related respiratory papillomatosis. Individual drugs and classes of psychotropics often had activity against multiple viruses, with promiscuity explained by shared viral or cellular targets. Safety profiles of psychotropics may be more tolerable in this context than when they are used long-term in the setting of psychiatric illness. Nonetheless, translation of in vitro results to the clinical arena has been slow. Psychotropic medications as a class deserve further study, including in clinical trials for repurposing as antiviral drugs for children and adults.

Adverse event following live attenuated chikungunya vaccine in a cynomolgus macaque with pre-existing chronic hydrocephalus

A cynomolgus macaque (Macaca fascicularis) with a pre-existing, undiagnosed, subclinical but severe cerebral hydrocephalus was enrolled in a study of long-term immunogenicity of the IRES/CHIK vaccine. The animal began showing signs of neurological dysfunction post-vaccination, which progressed and ultimately resulted in euthanasia. The underlying brain abnormality was revealed at necropsy and was subsequently investigated with gross and microscopic examination. This becomes the first reported case of an adverse event following administration of a live attenuated vaccine and suggests the possibility of an increased susceptibility risk of unwanted adverse outcome associated with vaccination in populations with pre-existing conditions such as hydrocephalus.

Role of microglia in central nervous system infections

The nature of microglia fascinated many prominent researchers in the 19th and early 20th centuries, and in a classic treatise in 1932, Pio del Rio-Hortega formulated a number of concepts regarding the function of these resident macrophages of the brain parenchyma that remain relevant to this day. However, a renaissance of interest in microglia occurred toward the end of the 20th century, fueled by the recognition of their role in neuropathogenesis of infectious agents, such as human immunodeficiency virus type 1, and by what appears to be their participation in other neurodegenerative and neuroinflammatory disorders. During the same period, insights into the physiological and pathological properties of microglia were gained from in vivo and in vitro studies of neurotropic viruses, bacteria, fungi, parasites, and prions, which are reviewed in this article. New concepts that have emerged from these studies include the importance of cytokines and chemokines produced by activated microglia in neurodegenerative and neuroprotective processes and the elegant but astonishingly complex interactions between microglia, astrocytes, lymphocytes, and neurons that underlie these processes. It is proposed that an enhanced understanding of microglia will yield improved therapies of central nervous system infections, since such therapies are, by and large, sorely needed.

NF-kappaB and virus infection: who controls whom

Among the different definitions of viruses, 'pirates of the cell' is one of the most picturesque, but also one of the most appropriate. Viruses have been known for a long time to utilize a variety of strategies to penetrate cells and, once inside, to take over the host nucleic acid and protein synthesis machinery to build up their own components and produce large amounts of viral progeny. As their genomes carry a minimal amount of information, encoding only a few structural and regulatory proteins, viruses are largely dependent on their hosts for survival; however, despite their apparent simplicity, viruses have evolved different replicative strategies that are regulated in a sophisticated manner. During the last years, the study of the elaborate relationship between viruses and their hosts has led to the understanding of how viral pathogens not only are able to alter the host metabolism via their signaling proteins, but are also able to hijack cellular signaling pathways and transcription factors, and control them to their own advantage. In particular, the nuclear factor-kappaB (NF-kappaB) pathway appears to be an attractive target for common human viral pathogens. This review summarizes what is known about the control of NF-kappaB by viruses, and discusses the possible outcome of NF-kappaB activation during viral infection, which may benefit either the host or the pathogen.

Diazepam inhibits HIV-1 Tat-induced migration of human microglia

During HIV-1 encephalitis, the chemotaxis-inducing activity of Tat may enhance the viral life cycle through recruitment of additional susceptible microglial cells to foci of infection. Benzodiazepines (BDZs) readily penetrate the blood-brain barrier and are known to possess anti-inflammatory properties. Pretreatment of human microglial cells with peripheral (Ro5-4864) and mixed (diazepam), but not central (clonazepam), benzodiazepine receptor ligands was found to potently suppress HIV-1 Tat-induced chemotaxis. Application of Tat to microglial cells evokes an increase in intracellular calcium concentration ([Ca(2+)]i) that rapidly desensitizes the cells. Diazepam's inhibitory effect was associated with its ability to block Tat-induced [Ca(2+)]i mobilization. These data support the notion that through their effects on microglia, peripheral BDZ receptor ligands could alter the neuropathogenesis of HIV-1.

Benzodiazepines, glia, and HIV-1 neuropathogenesis

Although the precise mechanisms whereby HIV-1 infection induces neurodegeneration have yet to be determined, a great deal of evidence has incriminated glial cells and the production of proinflammatory mediators in this pathologic process. For this reason, ideal therapeutic agents for the treatment of AIDS dementia would attenuate HIV-1 neuropathogenesis through both direct inhibition of viral expression and suppression of brain cell-produced immune mediators. Benzodiazepines (BDZs), such as Valium, are extensively prescribed drugs for anxiety disorders, which readily cross the blood-brain barrier and have demonstrated immunomodulatory properties. BDZs bind to primary human microglial cells, the principal site of HIV-1 replication in the brain, and inhibit lipopolysaccharide (LPS) induced tumour necrosis factor (TNF-alpha) production by these cells in a concentration-dependent manner. Treatment of HIV-1-infected primary human microglial, as well as mixed glial/neuronal, cell cultures with BDZs inhibits the expression of HIV-1 p24 antigen. BDZ-induced inhibition of HIV-1 expression in chronically infected promonocytic (U1) cells has been found to be associated with decreased activation of the nuclear transcription factor kappa B (NF-kappa B). Because HIV-1 expression is critically dependent on the cellular transcription machinery, inhibition of the activation of transcription factors, which participate in both HIV-1 expression and the production of neurotoxic immune mediators, by BDZ analogs may provide new therapeutic options for AIDS dementia.