Neurosteroid-mediated regulation of brain innate immunity in HIV/AIDS: DHEA-S suppresses neurovirulence

Effects of Opioid Withdrawal on Psychobiology in People Living with HIV

OBJECTIVE

Many persons with opioid use disorders (OUDs) have HIV disease and experience clinically significant stress after they enroll in abstinence-based treatment and undergo medically assisted withdrawal. We examined whether opioid withdrawal affects virologic control, inflammatory markers, cognition, and mood in persons with an OUD and HIV, and explored whether measures of withdrawal stress, such as activation of the HPA axis, contribute to alterations in immune function, cognition, and mood.

METHOD AND PARTICIPANTS

Study participants were 53 persons with HIV who were admitted for OUD treatment at the City Addiction Hospital in Saint Petersburg, Russian Federation. Participants were examined at admission, at the anticipated peak of withdrawal 3 to 7 days after the last day of a clonidine-based withdrawal process lasting 7 to 14 days, and 3 to 4 weeks after completing withdrawal. At these times, participants received medical exams and were evaluated for symptoms of withdrawal, as well as cognition and mood. Viral load, plasma cortisol, DHEA sulfate ester (DHEA-S), interleukin-6 (IL-6), and soluble CD14 (sCD14) were determined. Multivariable models examined the relationships between markers of HPA activation and the other parameters over time.

RESULTS

HPA activation as indexed by cortisol/DHEA-S ratio increased during withdrawal, as did markers of immune activation, IL-6 and sCD14. There were no significant associations between viral load and indicators of HPA activation. In longitudinal analyses, higher cortisol/DHEA sulfate was related to worse cognition overall, and more mood disturbance. Increase in IL-6 was associated with worse cognitive performance on a learning task. There were no significant associations with sCD14.

CONCLUSIONS

Worsening of cognition and measures of mood disturbance during withdrawal were associated with activation of the HPA axis and some measures of inflammation. Whether repeated episodes of opioid withdrawal have a cumulative impact on long-term HIV outcomes and neurocognition is a topic for further investigation.

Male sex hormones, aging, and inflammation

Adequate levels of androgens (eugonadism), and specifically testosterone, are vital compounds for male quality of life, longevity, and positive health outcomes. Testosterone exerts its effects by binding to the androgen receptor, which is expressed in numerous tissues throughout the body. Significant research has been conducted on the impact of this steroid hormone on skeletal, muscle and adipose tissues and on the cardiovascular, immune, and nervous systems. Testosterone levels have also been studied in relation to the impact of diseases, aging, nutrition and the environment on its circulating levels. Conversely, the impact of testosterone on health has also been evaluated with respect to its cardiac and vascular protective effects, body composition, autoimmunity and all-cause mortality. The male aging process results in decreasing testosterone levels over time. The exact mechanisms and impact of these changes in testosterone levels with age on health- and life-span are still not completely clear. Further research is needed to determine the optimal testosterone and androgen levels to protect from chronic age-related conditions such as frailty and osteoporosis.

Old plasma dilution reduces human biological age: a clinical study

This work extrapolates to humans the previous animal studies on blood heterochronicity and establishes a novel direct measurement of biological age. Our results support the hypothesis that, similar to mice, human aging is driven by age-imposed systemic molecular excess, the attenuation of which reverses biological age, defined in our work as a deregulation (noise) of 10 novel protein biomarkers. The results on biological age are strongly supported by the data, which demonstrates that rounds of therapeutic plasma exchange (TPE) promote a global shift to a younger systemic proteome, including youthfully restored pro-regenerative, anticancer, and apoptotic regulators and a youthful profile of myeloid/lymphoid markers in circulating cells, which have reduced cellular senescence and lower DNA damage. Mechanistically, the circulatory regulators of the JAK-STAT, MAPK, TGF-beta, NF-κB, and Toll-like receptor signaling pathways become more youthfully balanced through normalization of TLR4, which we define as a nodal point of this molecular rejuvenation. The significance of our findings is confirmed through big-data gene expression studies.

Age-related neuroendocrine, cognitive, and behavioral co-morbidities are promoted by HIV-1 Tat expression in male mice

In the U.S. about half of the HIV-infected individuals are aged 50 and older. In men living with HIV, secondary hypogonadism is common and occurs earlier than in seronegative men, and its prevalence increases with age. While the mechanisms(s) are unknown, the HIV-1 trans-activator of transcription (Tat) protein disrupts neuroendocrine function in mice partly by dysregulating mitochondria and neurosteroidogenesis. We hypothesized that conditional Tat expression in middle-aged male transgenic mice [Tat(+)] would promote age-related comorbidities compared to age-matched controls [Tat(−)]. We expected Tat to alter steroid hormone milieu consistent with behavioral deficits. Middle-aged Tat(+) mice had lower circulating testosterone and progesterone than age-matched controls and greater circulating corticosterone and central allopregnanolone than other groups. Young Tat(+) mice had greater circulating progesterone and estradiol-to-testosterone ratios. Older age or Tat exposure increased anxiety-like behavior (open field; elevated plus-maze), increased cognitive errors (radial arm water maze), and reduced grip strength. Young Tat(+), or middle-aged Tat(−), males had higher mechanical nociceptive thresholds than age-matched counterparts. Steroid levels correlated with behaviors. Thus, Tat may contribute to HIV-accelerated aging.

Allopregnanolone and neuroHIV: Potential benefits of neuroendocrine modulation in the era of antiretroviral therapy

Forty years into the HIV pandemic, approximately 50% of infected individuals still suffer from a constellation of neurological disorders collectively known as 'neuroHIV.' Although combination antiretroviral therapy (cART) has been a tremendous success, in its present form, it cannot eradicate HIV. Reservoirs of virus reside within the central nervous system, serving as sources of HIV virotoxins that damage mitochondria and promote neurotoxicity. Although understudied, there is evidence that HIV or the HIV regulatory protein, trans-activator of transcription (Tat), can dysregulate neurosteroid formation potentially contributing to endocrine dysfunction. People living with HIV commonly suffer from endocrine disorders, including hypercortisolemia accompanied by paradoxical adrenal insufficiency upon stress. Age-related comorbidities often onset sooner and with greater magnitude among people living with HIV and are commonly accompanied by hypogonadism. In the post-cART era, these derangements of the hypothalamic-pituitary-adrenal and -gonadal axes are secondary (i.e., relegated to the brain) and indicative of neuroendocrine dysfunction. We review the clinical and preclinical evidence for neuroendocrine dysfunction in HIV, the capacity for hormone therapeutics to play an ameliorative role and the future steroid-based therapeutics that may have efficacy as novel adjunctives to cART.

The Utilization of Dehydroepiandrosterone as a Sexual Hormone Precursor in Premenopausal and Postmenopausal Women: An Overview

Dehydroepiandrosterone (DHEA), and its metabolite, dehydroepiandrosterone sulfate ester (DHEAS), are the most abundant circulating steroid hormones, and are synthesized in the zona reticularis of the adrenal cortex, in the gonads, and in the brain. The precise physiological role of DHEA and DHEAS is not yet fully understood, but these steroid hormones can act as androgens, estrogens, and neurosteroids, and perform many roles in the human body. Since both levels decline with age, use of DHEA supplements have gained more attention due to being advertised as an antidote to aging in postmenopausal women, who may have concerns on age-related diseases and overall well-being. However, current research has not reached an overall consensus on the effects of DHEA on postmenopausal women. This overview is a summary of the current literature, addressing the metabolic pathway for DHEA synthesis and utilization, as well as the effects of DHEA on premenopausal and postmenopausal women with disease states and other factors. As for the therapeutic effects on menopausal syndrome and other age-related diseases, several studies have found that DHEA supplementations can alleviate vasomotor symptoms, preserve the integrity of the immune system, reduce bone loss, and increase muscle mass. Intravaginal DHEA has shown significant beneficial effects in menopausal women with severe vulvovaginal symptoms. On the other hand, DHEA supplements have not shown definitive effects in cardiovascular disease, adrenal insufficiency, insulin sensitivity, and cognition. Due to inadequate sample sizes and treatment durations of current studies, it is difficult to assess the safety and efficacy of DHEA and draw reliable conclusions for the physiological role, the optimal dosage, and the effects on premenopausal and postmenopausal women; therefore, the study of DHEA warrants future investigation. Further research into the roles of these steroid hormones may bring us closer to a therapeutic option in the future.

Infection of Glia by Human Pegivirus Suppresses Peroxisomal and Antiviral Signaling Pathways

Human pegivirus (HPgV) infects peripheral leukocytes but was recently shown to be a neurotropic virus associated with leukoencephalitis in humans. In the present study, we investigated the neural cell tropism of HPgV as well as its effects on host immune responses. HPgV wild type (WT) and a mutant virus with a deletion in the HPgV NS2 gene (ΔNS2) were able to productively infect human astrocytes and microglia but not neurons or an oligodendrocyte-derived cell line. Of note, the ΔNS2 virus replicated better than WT pegivirus in astrocytes, with both viruses being able to subsequently infect and spread in fresh human astrocyte cultures. Infection of human glia by HPgV WT and ΔNS2 viruses resulted in suppression of peroxisome-associated genes, including PEX11B, ABCD1, PEX7, ABCD3, PEX3, and PEX5L, during peak viral production, which was accompanied by reduced expression of IFNB, IRF3, IRF1, and MAVS, particularly in ΔNS2-infected cells. These data were consistent with analyses of brain tissue from patients infected with HPgV in which we observed suppression of peroxisome and type I interferon gene transcripts, including PEX11B, ABCD3, IRF1, and IRF3, with concurrent loss of PMP70 immunoreactivity in glia. Our data indicate that human astrocytes and microglia are permissive to HPgV infection, resulting in peroxisome injury and suppressed antiviral signaling that is influenced by viral diversity. IMPORTANCE Human pegiviruses are detected in 1 to 5% of the general population, principally infecting leukocytes, although their effects on human health remain uncertain. Here, we show that human pegivirus infects specific neural cell types in culture and human brain and, like other neurotropic flaviviruses, causes suppression of peroxisome and antiviral signaling pathways, which could favor ongoing viral infection and perhaps confer susceptibility to the development of neurological disease.

Comparison of the sex hormones' serum level in women with recurrent aphthous stomatitis and healthy population: a cross-sectional study

Background

In this study, we aimed to evaluate the sex hormonal serum level in patients with recurrent aphthous stomatitis and compare them with healthy participants.

Methods

This cross-sectional study was done on patients with recurrent aphthous stomatitis who had referred to Shiraz Dental Faculty, Oral and Maxillofacial Medicine Department during 2018–2019. The non -menopause women with recurrence of at least 3 lesions per year were enrolled in this study. The mean serum level of FSH, LH, PRL (prolactin), testosterone, DHT (Dihydrotestosterone), DHEA-S (Dehydroepiandrosterone sulfate), estradiol and progesterone of 30 participants in each group of case and control were measured and compared. The data were analyzed by SPSS version 18 and independent T-test, Mann–Whitney U test, Spearman’s correlation coefficient test, Chi-square test and Fisher’s test.

Results

The mean serum level of DHEA-S in patients with recurrent aphthous stomatitis (RAS) was significantly lower than the control group (p value = 0.02). In addition to DHEA-S, the mean serum level of testosterone was lower in the evaluation group although this difference was not significant (p value = 0.057). Considering the effect of age on the mean serum level of sex hormones, our results revealed that only DHEA-S mean serum level was decreased by increasing the age of participants in patients with RAS (p value = 0.018). The number of participants with abnormal range of testosterone (p value < 0.0001) and progesterone (p value = 0.037) serum level was significantly more in patients with RAS. The frequency of RAS in a year did not show a significant relationship with the serum level of the evaluated hormones.

Conclusion

The patients with RAS had a lower serum level of DHEA-S. The mean serum level of testosterone and progesterone was significantly abnormal in RAS patients.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12903-021-01812-9.

Microglial HIV-1 Expression: Role in HIV-1 Associated Neurocognitive Disorders

The persistence of HIV-1 viral reservoirs in the brain, despite treatment with combination antiretroviral therapy (cART), remains a critical roadblock for the development of a novel cure strategy for HIV-1. To enhance our understanding of viral reservoirs, two complementary studies were conducted to (1) evaluate the HIV-1 mRNA distribution pattern and major cell type expressing HIV-1 mRNA in the HIV-1 transgenic (Tg) rat, and (2) validate our findings by developing and critically testing a novel biological system to model active HIV-1 infection in the rat. First, a restricted, region-specific HIV-1 mRNA distribution pattern was observed in the HIV-1 Tg rat. Microglia were the predominant cell type expressing HIV-1 mRNA in the HIV-1 Tg rat. Second, we developed and critically tested a novel biological system to model key aspects of HIV-1 by infusing F344/N control rats with chimeric HIV (EcoHIV). In vitro, primary cultured microglia were treated with EcoHIV revealing prominent expression within 24 h of infection. In vivo, EcoHIV expression was observed seven days after stereotaxic injections. Following EcoHIV infection, microglia were the major cell type expressing HIV-1 mRNA, results that are consistent with observations in the HIV-1 Tg rat. Within eight weeks of infection, EcoHIV rats exhibited neurocognitive impairments and synaptic dysfunction, which may result from activation of the NogoA-NgR3/PirB-RhoA signaling pathway and/or neuroinflammation. Collectively, these studies enhance our understanding of HIV-1 viral reservoirs in the brain and offer a novel biological system to model HIV-associated neurocognitive disorders and associated comorbidities (i.e., drug abuse) in rats.

Do Dehydroepiandrosterone (DHEA) and Its Sulfate (DHEAS) Play a Role in the Stress Response in Domestic Animals?

In animal husbandry, stress is often associated with poor health and welfare. Stress occurs when a physiological control system detects a state of real or presumptive threat to the animal's homeostasis or a failure to control a fitness-critical variable. The definition of stress has mostly relied on glucocorticoids measurement, even though glucocorticoids represent one stress-response system, the hypothalamus-pituitary-adrenocortical axis, which is not precise enough as it is also related to metabolic regulation and activated in non-stressful situations (pleasure, excitement, and arousal). The mammal adrenal can synthesize the androgenic steroid dehydroepiandrosterone (DHEA) and its sulfate metabolite (DHEAS), which have been associated to the stress response in several studies performed mostly in humans and laboratory animals. Although the functions of these steroids are not fully understood, available data suggest their antagonistic effects on glucocorticoids and, in humans, their secretion is affected by stress. This review explores the scientific literature on DHEA and DHEAS release in domestic animals in response to stressors of different nature (inflammatory, physical, or social) and duration, and the extra-adrenal contribution to circulating DHEA. Then, the potential use of DHEA in conjunction with cortisol to improve the definition of the stress phenotype in farmed animals is discussed. Although the focus of this review is on farmed animals, examples from other species are reported when available.

Pregnane steroidogenesis is altered by HIV-1 Tat and morphine: Physiological allopregnanolone is protective against neurotoxic and psychomotor effects

Pregnane steroids, particularly allopregnanolone (AlloP), are neuroprotective in response to central insult. While unexplored in vivo, AlloP may confer protection against the neurological dysfunction associated with human immunodeficiency virus type 1 (HIV-1). The HIV-1 regulatory protein, trans-activator of transcription (Tat), is neurotoxic and its expression in mice increases anxiety-like behavior; an effect that can be ameliorated by progesterone, but not when 5α-reduction is blocked. Given that Tat's neurotoxic effects involve mitochondrial dysfunction and can be worsened with opioid exposure, we hypothesized that Tat and/or combined morphine would perturb steroidogenesis in mice, promoting neuronal death, and that exogenous AlloP would rescue these effects. Like other models of neural injury, conditionally inducing HIV-1 Tat in transgenic mice significantly increased the central synthesis of pregnenolone and progesterone's 5α-reduced metabolites, including AlloP, while decreasing central deoxycorticosterone (independent of changes in plasma). Morphine significantly increased brain and plasma concentrations of several steroids (including progesterone, deoxycorticosterone, corticosterone, and their metabolites) likely via activation of the hypothalamic-pituitary-adrenal stress axis. Tat, but not morphine, caused glucocorticoid resistance in primary splenocytes. In neurons, Tat depolarized mitochondrial membrane potential and increased cell death. Physiological concentrations of AlloP (0.1, 1, or 10 nM) reversed these effects. High-concentration AlloP (100 nM) was neurotoxic in combination with morphine. Tat induction in transgenic mice potentiated the psychomotor effects of acute morphine, while exogenous AlloP (1.0 mg/kg, but not 0.5 mg/kg) was ameliorative. Data demonstrate that steroidogenesis is altered by HIV-1 Tat or morphine and that physiological AlloP attenuates resulting neurotoxic and psychomotor effects.

Central intracrine DHEA synthesis in ageing-related neuroinflammation and neurodegeneration: therapeutic potential?

It is a well-known fact that DHEA declines on ageing and that it is linked to ageing-related neurodegeneration, which is characterised by gradual cognitive decline. Although DHEA is also associated with inflammation in the periphery, the link between DHEA and neuroinflammation in this context is less clear. This review drew from different bodies of literature to provide a more comprehensive picture of peripheral vs central endocrine shifts with advanced age—specifically in terms of DHEA. From this, we have formulated the hypothesis that DHEA decline is also linked to neuroinflammation and that increased localised availability of DHEA may have both therapeutic and preventative benefit to limit neurodegeneration. We provide a comprehensive discussion of literature on the potential for extragonadal DHEA synthesis by neuroglial cells and reflect on the feasibility of therapeutic manipulation of localised, central DHEA synthesis.

DHEA in Prenatal and Postnatal Life: Implications for Brain and Behavior

Dehydroepiandrosterone (DHEA) and its sulfated congener (DHEAS) are the principal C₁₉ steroid produced by the adrenal gland in many mammals, including humans. It is secreted in high concentrations during fetal life, but synthesis decreases after birth until, in humans and some other primates, there is a prepubertal surge of DHEA production by the adrenal gland-a phenomenon known as adrenarche. There remains considerable uncertainty about the physiological role of DHEA and DHEAS. Moreover, the origin of the trophic drives that determine the waxing and waning of DHEA synthesis are poorly understood. These gaps in knowledge arise in some measure from the difficulty of understanding mechanistic determinants from observations made opportunistically in humans and primates, and have stimulated a search for other suitable species that exhibit adrenarche- and adrenopause-like changes of adrenal function. DHEA and DHEAS are clearly neuroactive steroids with actions at several neurotransmitter receptors; indeed, DHEA is now known to be also synthesized by many parts of the brain, and this capacity undergoes ontogenic changes, but whether this is dependent or independent of the changes in adrenal synthesis is unknown. In this chapter we review key contributions to this field over the last 50+ years, and speculate on the importance of DHEA for the brain, both during development and for maturation and aging of cerebral function and behavior.

Neurologic disease in feline immunodeficiency virus infection: disease mechanisms and therapeutic interventions for NeuroAIDS

Feline immunodeficiency virus (FIV) is a lentivirus that causes immunosuppression through virus-mediated CD4+ T cell depletion in feline species. FIV infection is complicated by virus-induced disease in the nervous system. FIV enters the brain soon after primary infection and is detected as FIV-encoded RNA, DNA, and proteins in microglia, macrophages, and astrocytes. FIV infection activates neuroinflammatory pathways including cytokines, chemokines, proteases, and ROS with accompanying neuronal injury and loss. Neurobehavioral deficits during FIV infection are manifested as impaired motor and cognitive functions. Several treatment strategies have emerged from studies of FIV neuropathogenesis including the therapeutic benefits of antiretroviral therapies, other protease inhibitors, anti-inflammatory, and neurotrophic compounds. Recently, insulin's antiviral, anti-inflammatory, and neuroprotective effects were investigated in models of lentivirus brain infection. Insulin suppressed HIV-1 replication in human microglia as well as FIV replication of lymphocytes. Insulin treatment diminished cytokine and chemokine activation in HIV-infected microglia while also protecting neurons from HIV-1 Vpr protein-mediated neurotoxicity. Intranasal (IN) insulin delivery for 6 weeks suppressed FIV expression in the brains of treated cats. IN insulin also reduced neuroinflammation and protected neurons in the hippocampus, striatum, and neocortex of FIV-infected animals. These morphological and molecular effects of IN insulin were confirmed by neurobehavioral studies that showed IN insulin-treated FIV-infected animals displayed improved motor and cognitive performance compared to sham-treated FIV-infected animals. Thus, FIV infection of the nervous system provides a valuable comparative in vivo model for discovering and evaluating disease mechanisms as well as developing therapeutic strategies for NeuroAIDS in humans.

Neuroactive Steroids: Receptor Interactions and Responses

Neuroactive steroids (NASs) are naturally occurring steroids, which are synthesized centrally as de novo from cholesterol and are classified as pregnane, androstane, and sulfated neurosteroids (NSs). NASs modulate many processes via interacting with gamma-aminobutyric acid (GABA), N-methyl-d-aspartate, serotonin, voltage-gated calcium channels, voltage-dependent anion channels, α-adrenoreceptors, X-receptors of the liver, transient receptor potential channels, microtubule-associated protein 2, neurotrophin nerve growth factor, and σ1 receptors. Among these, NSs (especially allopregnanolone) have high potency and extensive GABA-A receptors and hence demonstrate anticonvulsant, anesthetic, central cytoprotectant, and baroreflex inhibitory effects. NSs are also involved in mood and learning via serotonin and anti-nociceptive activity via T-type voltage-gated Ca2+ channels. Moreover, they are modulators of mitochondrial function, synaptic plasticity, or regulators of apoptosis, which have a role in neuroprotective via voltage-dependent anion channels receptors. For proper functioning, NASs need to be in their normal level, whereas excess and deficiency may lead to abnormalities. When they are below the normal, NSs could have a part in development of depression, neuro-inflammation, multiple sclerosis, experimental autoimmune encephalitis, epilepsy, and schizophrenia. On the other hand, stress and attention deficit disorder could occur during excessive level. Overall, NASs are very important molecules with major neuropsychiatric activity.

Suppressed oligodendrocyte steroidogenesis in multiple sclerosis: Implications for regulation of neuroinflammation

Multiple sclerosis (MS) is an inflammatory demyelinating disease of the central nervous system (CNS). Neurosteroids are reported to exert anti-inflammatory effects in several neurological disorders. We investigated the expression and actions of the neurosteroid, dehydroepiandrosterone (DHEA), and its more stable 3β-sulphated ester, DHEA-S, in MS and associated experimental models. CNS tissues from patients with MS and animals with experimental autoimmune encephalomyelitis (EAE) displayed reduced DHEA concentrations, accompanied by diminished expression of the DHEA-synthesizing enzyme CYP17A1 in oligodendrocytes (ODCs), in association with increased expression of inflammatory genes including interferon (IFN)-γ and interleukin (IL)-1β. CYP17A1 was expressed variably in different human neural cell types but IFN-γ exposure selectively reduced CYP17A1 detection in ODCs. DHEA-S treatment reduced IL-1β and -6 release from activated human myeloid cells with minimal effect on lymphocyte viability. Animals with EAE receiving DHEA-S treatment showed reduced Il1b and Ifng transcript levels in spinal cord compared to vehicle-treated animals with EAE. DHEA-S treatment also preserved myelin basic protein immunoreactivity and reduced axonal loss in animals with EAE, relative to vehicle-treated EAE animals. Neurobehavioral deficits were reduced in DHEA-S-treated EAE animals compared with vehicle-treated animals with EAE. Thus, CYP17A1 expression in ODCs and its product DHEA were downregulated in the CNS during inflammatory demyelination while DHEA-S provision suppressed neuroinflammation, demyelination, and axonal injury that was evident as improved neurobehavioral performance. These findings indicate that DHEA production is an immunoregulatory pathway within the CNS and its restoration represents a novel treatment approach for neuroinflammatory diseases.

Exploring the potential of natural and synthetic neuroprotective steroids against neurodegenerative disorders: A literature review

Neurodegeneration is a complex process, which leads to progressive brain damage due to loss of neurons. Despite exhaustive research, the cause of neuronal loss in various degenerative disorders is not entirely understood. Neuroprotective steroids constitute an important line of attack, which could play a major role against the common mechanisms associated with various neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. Natural endogenous steroids induce the neuroprotection by protecting the nerve cells from neuronal injury through multiple mechanisms, therefore the structural modifications of the endogenous steroids could be helpful in the generation of new therapeutically useful neuroprotective agents. The review article will keep the readers apprised of the detailed description of natural as well as synthetic neuroprotective steroids from the medicinal chemistry point of view, which would be helpful in drug discovery efforts aimed toward neurodegenerative diseases.

HIV-1 Tat Primes and Activates Microglial NLRP3 Inflammasome-Mediated Neuroinflammation

Neuroinflammation associated with HIV-1 infection is a problem affecting ∼50% of HIV-infected individuals. NLR family pyrin domain containing 3 (NLRP3) inflammasome has been implicated in HIV-induced microglial activation, but the mechanism(s) remain unclear. Because HIV-1 Transactivator of Transcription (Tat) protein continues to be present despite antiretroviral therapy and activates NF-kB, we hypothesized that Tat could prime the NLRP3 inflammasome. We found a dose- and time-dependent induction of NLRP3 expression in microglia exposed to Tat compared with control. Tat exposure also time-dependently increased the mature caspase-1 and IL-1β levels and enhanced the IL-1β secretion. These in vitro findings were validated in archival brain tissues from Simian Immunodeficiency Virus (SIV)-infected and uninfected rhesus macaques. Further validation of NLRP3 priming in vivo involved administration of lipopolysaccharide (LPS) to HIV transgenic (Tg) rats followed by assessment of IL-1β mRNA expression and inflammasome activation (ASC oligomers and mature IL-1β). Intriguingly, LPS potentiated upregulation of IL-1β mRNA and inflammasome activation in HIV-Tg rats compared with the wild-type controls. Interestingly, we found an inverse relationship in the expression of NLRP3 and its negative regulator, miR-223, suggesting a miR-223-mediated mechanism for Tat-induced NLRP3 priming. Furthermore, blockade of NLRP3 resulted in decreased IL-1β secretion. Collectively, these findings suggest a novel role of Tat in priming and activating the NLRP3 inflammasome. Therefore, NLRP3 can be envisioned as a therapeutic target for ameliorating Tat-mediated neuroinflammation.SIGNIFICANCE STATEMENT Despite successful suppression of viremia with increased longevity in the era of combined antiretroviral therapy, chronic inflammation with underlying neurocognitive impairment continues to afflict almost 50% of infected individuals. Viral, bacterial, and cellular products have all been implicated in promoting the chronic inflammation found in these individuals. Understanding the molecular mechanism(s) by which viral proteins such as HIV-1 Transactivator of Transcription (Tat) protein can activate microglia is thus of paramount importance. Herein, we demonstrate a novel role of Tat in priming and activating NLR family pyrin domain containing 3 (NLRP3) inflammasomes in microglial cells and in HIV-Tg rats administered lipopolysaccharide. Targeting NLRP3 inflammasome pathway mediators could thus be developed as therapeutic interventions to alleviate or prevent neuroinflammation and subsequent cognitive impairment in HIV-positive patients.

Feline Immunodeficiency Virus Neuropathogenesis: A Model for HIV-Induced CNS Inflammation and Neurodegeneration

Feline Immunodeficiency virus (FIV), similar to its human analog human immunodeficiency virus (HIV), enters the central nervous system (CNS) soon after infection and establishes a protected viral reservoir. The ensuing inflammation and damage give rise to varying degrees of cognitive decline collectively known as HIV-associated neurocognitive disorders (HAND). Because of the similarities to HIV infection and disease, FIV has provided a useful model for both in vitro and in vivo studies of CNS infection, inflammation and pathology. This mini review summarizes insights gained from studies of early infection, immune cell trafficking, inflammation and the mechanisms of neuropathogenesis. Advances in our understanding of these processes have contributed to the development of therapeutic interventions designed to protect neurons and regulate inflammatory activity.

5α-reduced progestogens ameliorate mood-related behavioral pathology, neurotoxicity, and microgliosis associated with exposure to HIV-1 Tat

Human immunodeficiency virus (HIV) is associated with motor and mood disorders, likely influenced by reactive microgliosis and subsequent neural damage. We have recapitulated aspects of this pathology in mice that conditionally express the neurotoxic HIV-1 regulatory protein, trans-activator of transcription (Tat). Progestogens may attenuate Tat-related behavioral impairments and reduce neurotoxicity in vitro, perhaps via progesterone's 5α-reductase-dependent metabolism to the neuroprotective steroid, allopregnanolone. To test this, ovariectomized female mice that conditionally expressed (or did not express) central HIV-1 Tat were administered vehicle or progesterone (4mg/kg), with or without pretreatment of a 5α-reductase inhibitor (finasteride, 50mg/kg). Tat induction significantly increased anxiety-like behavior in an open field, elevated plus maze and a marble burying task concomitant with elevated protein oxidation in striatum. Progesterone administration attenuated anxiety-like effects in the open field and elevated plus maze, but not in conjunction with finasteride pretreatment. Progesterone also attenuated Tat-promoted protein oxidation in striatum, independent of finasteride pretreatment. Concurrent experiments in vitro revealed Tat (50nM)-mediated reductions in neuronal cell survival over 60h, as well as increased neuronal and microglial intracellular calcium, as assessed via fura-2 AM fluorescence. Co-treatment with allopregnanolone (100nM) attenuated neuronal death in time-lapse imaging and blocked the Tat-induced exacerbation of intracellular calcium in neurons and microglia. Lastly, neuronal-glial co-cultures were labeled for Iba-1 to reveal that Tat increased microglial numbers in vitro and co-treatment with allopregnanolone attenuated this effect. Together, these data support the notion that 5α-reduced pregnane steroids exert protection over the neurotoxic effects of HIV-1 Tat.

HIV protease inhibitors disrupt astrocytic glutamate transporter function and neurobehavioral performance

Objective:

The neurotoxic actions of the HIV protease inhibitors, amprenavir (APV) and lopinavir (LPV) were investigated.

Design:

With combination antiretroviral therapy (cART), HIV-infected persons exhibit neurocognitive impairments, raising the possibility that cART might exert adverse central nervous system (CNS) effects. We examined the effects of LPV and APV using in-vitro and in-vivo assays of CNS function.

Methods:

Gene expression, cell viability and amino-acid levels were measured in human astrocytes, following exposure to APV or LPV. Neurobehavioral performance, amino-acid levels and neuropathology were examined in HIV-1 Vpr transgenic mice after treatment with APV or LPV.

Results:

Excitatory amino-acid transporter-2 (EAAT2) expression was reduced in astrocytes treated with LPV or APV, especially LPV (P < 0.05), which was accompanied by reduced intracellular l-glutamate levels in LPV-treated cells (P < 0.05). Treatment of astrocytes with APV or LPV reduced the expression of proliferating cell nuclear antigen (PCNA) and Ki-67 (P < 0.05) although cell survival was unaffected. Exposure of LPV to astrocytes augmented glutamate-evoked transient rises in [Ca_i] (P < 0.05). Vpr mice treated with LPV showed lower concentrations of l-glutamate, l-aspartate and l-serine in cortex compared with vehicle-treated mice (P < 0.05). Total errors in T-maze assessment were increased in LPV and APV-treated animals (P < 0.05). EAAT2 expression was reduced in the brains of protease inhibitor-treated animals, which was associated with gliosis (P < 0.05).

Conclusion:

These results indicated that contemporary protease inhibitors disrupt astrocyte functions at therapeutic concentrations with enhanced sensitivity to glutamate, which can lead to neurobehavioral impairments. ART neurotoxicity should be considered in future therapeutic regimens for HIV/AIDS.

Neuroprotective properties of dehydroepiandrosterone-sulfate and its relationship to interleukin 6 after aneurysmal subarachnoid hemorrhage: a prospective cohort study

INTRODUCTION

The established neuroprotective property of the sex steroid precursor dehydroepiandrosterone-sulfate (DHEAS) has not yet been investigated in the context of aneurysmal subarachnoid hemorrhage (aSAH). The influence of DHEAS on inflammatory response resulting in modulation of interleukin 6 (IL-6) synthesis has been shown. Here, we evaluate DHEAS serum levels after aSAH (day 0-14) and levels of IL-6 related to functional outcome at discharge and at six months.

METHODS

A complete data set (DHEAS and IL-6 serum levels for days 0, 1, 4, 7, 10 and 14 after aSAH) and outcome assessment at discharge according to modified Rankin Scale score (mRS) was available for 53 patients of the initially screened cohort (n = 109). Outcome assessment six months after aSAH was obtained from 41 patients. Logarithmized levels of DHEAS and IL-6 were related to dichotomized functional outcome either assessed at discharge or at six months. A mixed between-within subjects ANOVA was applied for statistical analysis (SPSS 21.0).

RESULTS

DHEAS and IL-6 levels across time were related to functional outcome. Regarding outcome assessment at discharge and at six months after aSAH, DHEAS levels (transformed to square root for statistical purposes) were considerably higher in patients with favorable outcome (mRS 0-2) (p = .001; p = .020). Inversely, in patients with favorable outcome either at discharge or six months after aSAH, lower IL-6 levels (logarithmized for statistical purposes) were observed across time (both p < .001).

CONCLUSION

We provide new evidence that DHEAS is associated with protective properties resulting in improvement of functional outcome after aSAH, possibly by influencing the inflammatory response after aSAH shown in the decreasing IL-6 serum levels. But the results for outcome six months after SAH are limited due to a high drop-out rate.

Hypothalamic-pituitary-adrenal axis in HIV infection and disease

HIV infection induces hypothalamic-pituitary-adrenal (HPA) axis derangements. Partial glucocorticoid resistance has been observed in a subset of AIDS patients, possibly owing to HIV-induced altered cytokine secretion and action. Because glucocorticoids have immunomodulatory effects, the severity of the HPA axis disorder could play a central role in disease progression. The characteristic phenotype of AIDS patients (visceral obesity, lipodystrophy) may be owing to effects of HIV proteins on the HPA axis, including changes in glucocorticoid and insulin sensitivity of target tissues, as well as altered cytokine production and interaction with the HPA axis, genetic causes, comorbidities, and, possibly, use of antiretroviral agents.

Role of anti-inflammatory compounds in human immunodeficiency virus-1 glycoprotein120-mediated brain inflammation

BACKGROUND

Neuroinflammation is a common immune response associated with brain human immunodeficiency virus-1 (HIV-1) infection. Identifying therapeutic compounds that exhibit better brain permeability and can target signaling pathways involved in inflammation may benefit treatment of HIV-associated neurological complications. The objective of this study was to implement an in vivo model of brain inflammation by intracerebroventricular administration of the HIV-1 viral coat protein gp120 in rats and to examine anti-inflammatory properties of HIV adjuvant therapies such as minocycline, chloroquine and simvastatin.

METHODS

Male Wistar rats were administered a single dose of gp120ADA (500 ng) daily for seven consecutive days, intracerebroventricularly, with or without prior intraperitoneal administration of minocycline, chloroquine or simvastatin. Maraviroc, a CCR5 antagonist, was administered intracerebroventricularly prior to gp120 administration for seven days as control. Real-time qPCR was used to assess gene expression of inflammatory markers in the frontal cortex, hippocampus and striatum. Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) secretion in cerebrospinal fluid (CSF) was measured applying ELISA. Protein expression of mitogen-activated protein kinases (MAPKs) (extracellular signal-related kinase 1/2 (ERK1/2), c-Jun N-terminal kinases (JNKs) and P38 kinases (P38Ks)) was detected using immunoblot analysis. Student's t-test and ANOVA were applied to determine statistical significance.

RESULTS

In gp120ADA-injected rats, mRNA transcripts of interleukin-1β (IL-1β) and inducible nitric oxide synthase (iNOS) were significantly elevated in the frontal cortex, striatum and hippocampus compared to saline or heat-inactivated gp120-injected controls. In CSF, a significant increase in TNF-α and IL-1β was detected. Maraviroc reduced upregulation of these markers suggesting that the interaction of R5-tropic gp120 to CCR5 chemokine receptor is critical for induction of an inflammatory response. Minocycline, chloroquine or simvastatin attenuated upregulation of IL-1β and iNOS transcripts in different brain regions. In CSF, minocycline suppressed TNF-α and IL-1β secretion, whereas chloroquine attenuated IL-1β secretion. In gp120-injected animals, activation of ERK1/2 and JNKs was observed in the hippocampus and ERK1/2 activation was significantly reduced by the anti-inflammatory agents.

CONCLUSIONS

Our data demonstrate that anti-inflammatory compounds can completely or partially reverse gp120-associated brain inflammation through an interaction with MAPK signaling pathways and suggest their potential role in contributing towards the prevention and treatment of HIV-associated neurological complications.

Rapid inflammasome activation in microglia contributes to brain disease in HIV/AIDS

Background

Human immunodeficiency virus type 1(HIV-1) infects and activates innate immune cells in the brain resulting in inflammation and neuronal death with accompanying neurological deficits. Induction of inflammasomes causes cleavage and release of IL-1β and IL-18, representing pathogenic processes that underlie inflammatory diseases although their contribution HIV-associated brain disease is unknown.

Results

Investigation of inflammasome-associated genes revealed that IL-1β, IL-18 and caspase-1 were induced in brains of HIV-infected persons and detected in brain microglial cells. HIV-1 infection induced pro-IL-1β in human microglia at 4 hr post-infection with peak IL-1β release at 24 hr, which was accompanied by intracellular ASC translocation and caspase-1 activation. HIV-dependent release of IL-1β from a human macrophage cell line, THP-1, was inhibited by NLRP3 deficiency and high extracellular [K⁺]. Exposure of microglia to HIV-1 gp120 caused IL-1β production and similarly, HIV-1 envelope pseudotyped viral particles induced IL-1β release, unlike VSV-G pseudotyped particles. Infection of cultured feline macrophages by the related lentivirus, feline immunodeficiency virus (FIV), also resulted in the prompt induction of IL-1β. In vivo FIV infection activated multiple inflammasome-associated genes in microglia, which was accompanied by neuronal loss in cerebral cortex and neurological deficits. Multivariate analyses of data from FIV-infected and uninfected animals disclosed that IL-1β, NLRP3 and caspase-1 expression in cerebral cortex represented key molecular determinants of neurological deficits.

Conclusions

NLRP3 inflammasome activation was an early and integral aspect of lentivirus infection of microglia, which was associated with lentivirus-induced brain disease. Inflammasome activation in the brain might represent a potential target for therapeutic interventions in HIV/AIDS.

HIV replication alters the composition of extrinsic pathway coagulation factors and increases thrombin generation

Background

HIV infection leads to activation of coagulation, which may increase the risk for atherosclerosis and venous thromboembolic disease. We hypothesized that HIV replication increases coagulation potentially through alterations in extrinsic pathway factors.

Methods and Results

Extrinsic pathway factors were measured among a subset of HIV participants from the Strategies for Management of Anti‐Retroviral Therapy (SMART) trial. Thrombin generation was estimated using validated computational modeling based on factor composition. We characterized the effect of antiretroviral therapy (ART) treatment versus the untreated state (HIV replication) via 3 separate analyses: (1) a cross‐sectional comparison of those on and off ART (n=717); (2) a randomized comparison of deferring versus starting ART (n=217); and (3) a randomized comparison of stopping versus continuing ART (n=500). Compared with viral suppression, HIV replication consistently showed short‐term increases in some procoagulants (eg, 15% to 23% higher FVIII; P<0.001) and decreases in key anticoagulants (eg, 5% to 9% lower antithrombin [AT] and 6% to 10% lower protein C; P<0.01). The net effect of HIV replication was to increase coagulation potential (eg, 24% to 48% greater thrombin generation from computational models; P<0.01 for all). The pattern of changes from HIV replication was reversed with ART treatment and consistent across all 3 independent comparisons.

Conclusions

HIV replication leads to complex changes in extrinsic pathway factors, with the net effect of increasing coagulation potential to a degree that may be clinically relevant. The key influence of changes in FVIII and AT suggests that HIV‐related coagulation abnormalities may involve changes in hepatocyte function in the context of systemic inflammation.

Clinical Trial Registration

URL: ClinicalTrials.gov. Unique identifier: NCT00027352.