Human immunodeficiency virus protein Tat induces oligodendrocyte injury by enhancing outward K+ current conducted by KV1.3

The Phosphorylation of Kv1.3: A Modulatory Mechanism for a Multifunctional Ion Channel

The voltage-gated potassium channel Kv1.3 plays a pivotal role in a myriad of biological processes, including cell proliferation, differentiation, and apoptosis. Kv1.3 undergoes fine-tuned regulation, and its altered expression or function correlates with tumorigenesis and cancer progression. Moreover, posttranslational modifications (PTMs), such as phosphorylation, have evolved as rapid switch-like moieties that tightly modulate channel activity. In addition, kinases are promising targets in anticancer therapies. The diverse serine/threonine and tyrosine kinases function on Kv1.3 and the effects of its phosphorylation vary depending on multiple factors. For instance, Kv1.3 regulatory subunits (KCNE4 and Kvβ) can be phosphorylated, increasing the complexity of channel modulation. Scaffold proteins allow the Kv1.3 channelosome and kinase to form protein complexes, thereby favoring the attachment of phosphate groups. This review compiles the network triggers and signaling pathways that culminate in Kv1.3 phosphorylation. Alterations to Kv1.3 expression and its phosphorylation are detailed, emphasizing the importance of this channel as an anticancer target. Overall, further research on Kv1.3 kinase-dependent effects should be addressed to develop effective antineoplastic drugs while minimizing side effects. This promising field encourages basic cancer research while inspiring new therapy development.

Elevated Systemic Inflammation Is Associated with Reduced Corticolimbic White Matter Integrity in Depression

(1) Background: Growing evidence indicates that inflammation can induce neural circuit dysfunction and plays a vital role in the pathogenesis of major depressive disorder (MDD). Nevertheless, whether inflammation affects the integrity of white matter pathways is only beginning to be explored. (2) Methods: We computed quantitative anisotropy (QA) from diffusion magnetic resonance imaging as an index of white matter integrity and regressed QA on C-reactive protein (CRP), controlling for age, sex, and BMI, in 176 participants with MDD. (3) Results: The QA values of several white matter tracts were negatively correlated with CRP concentration (standardized beta coefficient = -0.22, 95%CI = -0.38--0.06, FDR < 0.05). These tracts included the bilateral cortico-striatal tracts, thalamic radiations, inferior longitudinal fasciculi, corpus callosum (the forceps minor portion and the tapetum portion), cingulum bundles, and the left superior longitudinal fasciculus III. Importantly, the association remained robust after regressing up to twelve potential confounders. The bilateral fornix and a small portion of the thalamic radiation showed a positive association with CRP levels, but these associations did not remain significant after adjusting for confounders. (4) Conclusions: Peripheral inflammation may contribute to the etiology of MDD by impacting the microstructural integrity of brain corticolimbic white matter pathways.

The Manifesto of Pharmacoenosis: Merging HIV Pharmacology into Pathocoenosis and Syndemics in Developing Countries

Pathocoenosis and syndemics theories have emerged in the last decades meeting the frequent need of better understanding interconnections and reciprocal influences that coexistent communicable and non-communicable diseases play in a specific population. Nevertheless, the attention to pharmacokinetic and pharmacodynamics interactions of co-administered drugs for co-present diseases is to date limitedly paid to alert against detrimental pharmacological combos. Low and middle-income countries are plagued by the highest burden of HIV, tuberculosis, malaria, and helminthiasis, and they are experiencing an alarming rise in non-communicable disorders. In these settings, co-infections and comorbidities are common, but no tailored prescribing nor clinical trials are used to assess and exploit existing opportunities for the simultaneous and potentially synergistic treatment of intertwined diseases. Pharmacoenosis is the set of interactions that take place within a host as well as within a population due to the compresence of two or more diseases and their respective treatments. This framework should pilot integrated health programmes and routine clinical practice to face drug–drug interaction issues, avoiding negative co-administrations but also exploiting potential favourable ones to make the best out of the worst situations; still, to date, guiding data on the latter possibility is limited. Therefore, in this narrative review, we have briefly described both detrimental and favourable physiopathological interactions between HIV and other common co-occurring pathologies (malaria, tuberculosis, helminths, and cardiovascular disorders), and we have presented examples of advantageous potential pharmacological interactions among the drugs prescribed for these diseases from a pharmacokinetics, pharmacodynamics, and pharmacogenetics standpoint.

IL-17 Inhibits Oligodendrocyte Progenitor Cell Proliferation and Differentiation by Increasing K+ Channel Kv1.3

Interleukin 17 (IL-17) is a signature cytokine of Th17 cells. IL-17 level is significantly increased in inflammatory conditions of the CNS, including but not limited to post-stroke and multiple sclerosis. IL-17 has been detected direct toxicity on oligodendrocyte (Ol) lineage cells and inhibition on oligodendrocyte progenitor cell (OPC) differentiation, and thus promotes myelin damage. The cellular mechanism of IL-17 in CNS inflammatory diseases remains obscure. Voltage-gated K⁺ (Kv) channel 1.3 is the predominant Kv channel in Ol and potentially involved in Ol function and cell cycle regulation. Kv1.3 of T cells involves in immunomodulation of inflammatory progression, but the role of Ol Kv1.3 in inflammation-related pathogenesis has not been fully investigated. We hypothesized that IL-17 induces myelin injury through Kv1.3 activation. To test the hypothesis, we studied the involvement of OPC/Ol Kv1.3 in IL-17-induced Ol/myelin injury in vitro and in vivo. Kv1.3 currents and channel expression gradually decreased during the OPC development. Application of IL-17 to OPC culture increased Kv1.3 expression, leading to a decrease of AKT activation, inhibition of proliferation and myelin basic protein reduction, which were prevented by a specific Kv1.3 blocker 5-(4-phenoxybutoxy) psoralen. IL-17-caused myelin injury was validated in LPC-induced demyelination mouse model, particularly in corpus callosum, which was also mitigated by aforementioned Kv1.3 antagonist. IL-17 altered Kv1.3 expression and resultant inhibitory effects on OPC proliferation and differentiation may by interrupting AKT phosphorylating activation. Taken together, our results suggested that IL-17 impairs remyelination and promotes myelin damage by Kv1.3-mediated Ol/myelin injury. Thus, blockade of Kv1.3 as a potential therapeutic strategy for inflammatory CNS disease may partially attribute to the direct protection on OPC proliferation and differentiation other than immunomodulation.

HIV-induced neuroinflammation inhibits oligodendrocyte maturation via glutamate-dependent activation of the PERK arm of the integrated stress response

Despite combined antiretroviral therapy (cART), HIV-associated neurocognitive disorder (HAND) affects 30-50% of HIV-positive patients. Importantly, persistent white matter pathologies, specifically corpus callosum thinning and disruption of white matter microstructures observed in patients with HAND despite viral control through cART, raise the possibility that HIV infection in the setting of suboptimal cART may perturb oligodendrocyte (OL) maturation, function and/or survival, influencing HAND persistence in the cART era. To examine the effect of HIV infection on OL maturation, we used supernatants of primary human monocyte-derived macrophages infected with HIV (HIV/MDMs) to treat primary cultures of rat oligodendrocyte precursor cells (OPCs) during their differentiation to mature OLs. Using immunostaining for lineage-specific markers, we found that HIV/MDMs significantly inhibited OPC maturation. Based on our previous studies, we examined the potential role of several signaling pathways, including ionotropic glutamate receptors and the integrated stress response (ISR), and found that AMPA receptors (AMPAR)/kainic acid (KA) receptors (KARs) mediated the HIV/MDMs-induced defect in OL maturation. We also found that the treatment of OPC cultures with glutamate or AMPAR/KAR agonists phenocopied this effect. Blocking ISR activation, specifically the PERK arm of the ISR, protected OPCs from HIV/MDMs-mediated inhibition of OL maturation. Further, while glutamate, AMPA, and KA activated the ISR, inhibition of AMPAR/KAR activation prevented ISR induction in OPCs and rescued OL maturation. Collectively, these data identify glutamate signaling via ISR activation as a potential therapeutic pathway to ameliorate white matter pathologies in HAND and highlight the need for further investigation of their contribution to cognitive impairment.

Replicable association between human cytomegalovirus infection and reduced white matter fractional anisotropy in major depressive disorder

Major depressive disorder (MDD) is associated with reductions in white matter microstructural integrity as measured by fractional anisotropy (FA), an index derived from diffusion tensor imaging (DTI). The neurotropic herpesvirus, human cytomegalovirus (HCMV), is a major cause of white matter pathology in immunosuppressed populations but its relationship with FA has never been tested in MDD despite the presence of inflammation and weakened antiviral immunity in a subset of depressed patients. We tested the relationship between FA and HCMV infection in two independent samples consisting of 176 individuals with MDD and 44 healthy controls (HC) (Discovery sample) and 88 participants with MDD and 48 HCs (Replication sample). Equal numbers of HCMV positive (HCMV+) and HCMV negative (HCMV-) groups within each sample were balanced on ten different clinical/demographic variables using propensity score matching. Anti-HCMV IgG antibodies were measured using a solid-phase ELISA. In the Discovery sample, significantly lower FA was observed in the right inferior fronto-occipital fasciculus (IFOF) in HCMV+ participants with MDD compared to HCMV- participants with MDD (cluster size 1316 mm3; pFWE < 0.05, d = -0.58). This association was confirmed in the replication sample by extracting the mean FA from this exact cluster and applying the identical statistical model (p < 0.05, d = -0.45). There was no significant effect of diagnosis or interaction between diagnosis and HCMV in either sample. The effect of chronic HCMV infection on white matter integrity may-in at-risk individuals-contribute to the psychopathology of depression. These findings may provide a novel target of intervention for a subgroup of patients with MDD.

Functional impact of HIV-1 Tat on cells of the CNS and its role in HAND

Human immunodeficiency virus type 1 (HIV-1) transactivator of transcription (Tat) is a potent mediator involved in the development of HIV-1-associated neurocognitive disorders (HAND). Tat is expressed even in the presence of antiretroviral therapy (ART) and is able to enter the central nervous system (CNS) through a variety of ways, where Tat can interact with microglia, astrocytes, brain microvascular endothelial cells, and neurons. The presence of low concentrations of extracellular Tat alone has been shown to lead to dysregulated gene expression, chronic cell activation, inflammation, neurotoxicity, and structural damage in the brain. The reported effects of Tat are dependent in part on the specific HIV-1 subtype and amino acid length of Tat used. HIV-1 subtype B Tat is the most common subtype in North American and therefore, most studies have been focused on subtype B Tat; however, studies have shown many genetic, biologic, and pathologic differences between HIV subtype B and subtype C Tat. This review will focus primarily on subtype B Tat where the full-length protein is 101 amino acids, but will also consider variants of Tat, such as Tat 72 and Tat 86, that have been reported to exhibit a number of distinctive activities with respect to mediating CNS damage and neurotoxicity.

Opioid and neuroHIV Comorbidity - Current and Future Perspectives

With the current national opioid crisis, it is critical to examine the mechanisms underlying pathophysiologic interactions between human immunodeficiency virus (HIV) and opioids in the central nervous system (CNS). Recent advances in experimental models, methodology, and our understanding of disease processes at the molecular and cellular levels reveal opioid-HIV interactions with increasing clarity. However, despite the substantial new insight, the unique impact of opioids on the severity, progression, and prognosis of neuroHIV and HIV-associated neurocognitive disorders (HAND) are not fully understood. In this review, we explore, in detail, what is currently known about mechanisms underlying opioid interactions with HIV, with emphasis on individual HIV-1-expressed gene products at the molecular, cellular and systems levels. Furthermore, we review preclinical and clinical studies with a focus on key considerations when addressing questions of whether opioid-HIV interactive pathogenesis results in unique structural or functional deficits not seen with either disease alone. These considerations include, understanding the combined consequences of HIV-1 genetic variants, host variants, and μ-opioid receptor (MOR) and HIV chemokine co-receptor interactions on the comorbidity. Lastly, we present topics that need to be considered in the future to better understand the unique contributions of opioids to the pathophysiology of neuroHIV. Graphical Abstract Blood-brain barrier and the neurovascular unit. With HIV and opiate co-exposure (represented below the dotted line), there is breakdown of tight junction proteins and increased leakage of paracellular compounds into the brain. Despite this, opiate exposure selectively increases the expression of some efflux transporters, thereby restricting brain penetration of specific drugs.

The versatile Kv channels in the nervous system: actions beyond action potentials

Voltage-gated K+ (Kv) channel opening repolarizes excitable cells by allowing K+ efflux. Over the last two decades, multiple Kv functions in the nervous system have been found to be unrelated to or beyond the immediate control of excitability, such as shaping action potential contours or regulation of inter-spike frequency. These functions include neuronal exocytosis and neurite formation, neuronal cell death, regulation of astrocyte Ca2+, glial cell and glioma proliferation. Some of these functions have been shown to be independent of K+ conduction, that is, they suggest the non-canonical functions of Kv channels. In this review, we focus on neuronal or glial plasmalemmal Kv channel functions which are unrelated to shaping action potentials or immediate control of excitability. Similar functions in other cell types will be discussed to some extent in appropriate contexts.

Untreated Patients Dying With AIDS Have Loss of Neocortical Neurons and Glia Cells

Untreated human immunodeficiency virus (HIV) depletes its host CD4 cells, ultimately leading to acquired immunodeficiency syndrome (AIDS). In brain, the HIV confines itself to astrocytes and microglia, the resident brain macrophages, but does not infect oligodendrocytes and neurons. Nonetheless, cognitive symptoms associated with HIV and AIDS are attributed to loss of axons and white matter damage. We used design-based stereology to estimate the numbers of neocortical neurons and glial cells (astrocytes, oligodendrocytes, and microglia), in a series of 12 patients dying with AIDS before the era of retroviral treatments, and in 13 age-matched control brains. Relative to the control material, there was a 19% loss of neocortical neuron (p = 0.04) and a 29% reduction of oligodendrocytes (p = 0.003) in the patients with AIDS, whereas astrocyte and microglia numbers did not differ between patients and controls. Furthermore, we saw a 17% reduction in mean hemispheric volume in the AIDS group (p = 0.0015), which was driven by neocortical and white matter loss (p < 0.05), while the archicortex, subcortical gray matter, and ventricular volumes were within normal limits. Our results confirm previous reports of neuronal loss in AIDS. The new finding of oligodendrocyte loss supports the proposal that HIV in the brain provokes demyelination and axonal dysfunction and suggests that remyelination treatment strategies may be beneficial to patients suffering from HIV-associated neurocognitive deficits.

Mutant BCL11B in a Patient With a Neurodevelopmental Disorder and T-Cell Abnormalities

Background: BCL11B encodes B-cell lymphoma/leukemia 11B, a transcription factor that participates in the differentiation and migration of neurons and lymphocyte cells. De novo mutations of BCL11B have been associated with neurodevelopmental disorder and immunodeficiency, such as immunodeficiency 49 (IMD49) and intellectual developmental disorder with speech delay, dysmorphic facies, and T-cell abnormalities (IDDSFTA). However, the pathogenesis of the neurodevelopmental disorder and T-cell deficiency is still mysterious. The strategy to distinguish these two diseases in detail is also unclear. Methods: A patient with unique clinical features was identified. Multiple examinations were applied for evaluation. Whole-exome sequencing (WES) and Sanger sequencing were also performed for the identification of the disease-causing mutation. Results: We reported a 17-month-old girl with intellectual disability, speech impairment, and delay in motor development. She presented with mild dysmorphic facial features and weak functional movement. MRI indicated the abnormal myelination of the white matter. Immunological analysis showed normal levels of RTEs and γδT cells but a deficiency of naive T cells. Genetic sequencing identified a de novo heterozygous frameshift mutation c.1192_1196delAGCCC in BCL11B. Conclusions: An IDDSFTA patient of East Asian origin was reported. The unreported neurological display, immunophenotype, and a novel disease-causing mutation of the patient extended the spectrum of clinical features and genotypes of IDDSFTA.

Evaluation of apamin effects on myelination process in C57BL/6 mice model of multiple sclerosis

Multiple sclerosis (MS) is a demyelinating disease that causes chronic inflammation in the central nervous system. The aim of this study was to investigate the effects of apamin administration on myelination process. MS was induced by feeding cuprizone pellets (0.2%) for 6 weeks (demyelination phase) followed by normal feeding for additional 2 weeks (remyelination phase). Briefly, C57BL/6 male mice were randomly divided into six groups. Group 1, received the regular food pellets. Group 2 contained two subgroups of 6 animals each (n = 2 × 6). First group received cuprizone for 6 weeks and the sacrificed while the second group after 6 weeks of cuprizone, received no treatment for additional 2 weeks. Group 3 (co-treatment group) was composed of two subgroups of 6 animals each (n = 2 × 6). Both subgroups received apamin (100 μg/kg) intraperitoneally twice a week for 6 weeks. First subgroup terminated at this time and the second subgroup was fed normal diet for two additional weeks. Group 4 (post-treatment, n = 6) received apamin (100 μg/kg) intraperitoneally twice a week for 2 weeks after cuprizone secession. Groups 5 and 6 (vehicle, n = 6 in each group) received phosphate buffered saline as the vehicle of apamin during demyelination and remyelination phase. At the end of each phase, mice were deeply anesthetized and perfused. Groups 5 and 6 (vehicle) received PBS as the vehicle during both phases. Mice were anesthetized, perfused with PBS through their heart, and their brains were removed. Brain sections stained with luxol fast blue and the images were analyzed. Apamin co-treatment significantly increased the myelin content as compared to the cuprizone group. Also, mild elevation in the myelinated areas was observed with apamin post-treatment in comparison with remyelination phase. Our results revealed that apamin prevents myelin destruction more significantly as compared to remyelination process. This observation explains the possible role of apamin in inhibiting the activation of the microglia cells than stimulation of the oligodendrocytic precursor cells.

White matter loss and oligodendrocyte dysfunction in HIV: A consequence of the infection, the antiretroviral therapy or both?

While the severe cognitive effects of HIV-associated dementia have been reduced by combined antiretroviral therapy (cART), nearly half of HIV-positive (HIV+) patients still suffer from some form of HIV-Associated Neurocognitive Disorders (HAND). While frank neuronal loss has been dramatically reduced in HAND patients, white matter loss, including dramatic thinning of the corpus callosum, and loss of volume and structural integrity of myelin persists despite viral control by cART. It remains unclear whether changes in white matter underlie the clinical manifestation seen in patients or whether they are the result of persistent viral reservoirs, remnant damage from the acute infection, the antiretroviral compounds used to treat HIV, secondary effects due to peripheral toxicities or other associated comorbid conditions. Both HIV infection itself and its treatment with antiretroviral drugs can induce metabolic syndrome, lipodystrophy, atherosclerosis and peripheral neuropathies by increased oxidative stress, induction of the unfolded protein response and dysregulation of lipid metabolism. These virally and/or cART-induced processes can also cause myelin loss in the CNS. This review aims to highlight existing data on the contribution of white matter damage to HAND and explore the mechanisms by which HIV infection and its treatment contribute to persistence of white matter changes in people living with HIV currently on cART.

Aging and HIV-1 alter the function of specific K+ channels in prefrontal cortex pyramidal neurons

The medial prefrontal cortex (mPFC) is a key regulator of neurocognition. The glutamatergic pyramidal neurons are the predominant component of neurons in the mPFC. Aging and HIV profoundly alter the structure and function of mPFC pyramidal neurons, including, but are not limited to, dysregulation of NMDA receptors and voltage-gated calcium channels. Here we assessed the impact of aging and in vivo HIV exposure on the functional activity (firing) of mPFC pyramidal neurons mediated by voltage-gated K⁺ (K_v) channels and inwardly-rectifying K⁺ (K_ir) channels using patch-clamp recording in rat brain slices ex vivo. We found that aging and HIV significantly affect firing in different manners by altering the activity of K_v and likely K_ir channels, associated with changes in membrane properties and the mRNA levels of specific K_v channels. Evoked firing was significantly decreased in mPFC neurons of older (12 month, 12 m) rats compared to younger (6/7 week, 6/7wk) rats, regardless of HIV status. In contrast, firing was significantly increased in neurons from Tg rats compared to non-Tg rats, regardless of age. Aging/HIV-induced alterations in firing were mediated by dysfunctional K_v channels and K_ir channels, which exhibit significant changes in their activity and/or expression induced by aging and HIV exposure in vivo. Collectively, these novel findings demonstrate that aging is associated with a significant decline of mPFC neuronal activity; while long-term HIV exposure in vivo could drive mPFC neurons from over-activation to loss of firing, which could ultimately exacerbate the decline of mPFC neuronal activity.