Direct interaction of HIV gp120 with neuronal CXCR4 and CCR5 receptors induces cofilin-actin rod pathology via a cellular prion protein- and NOX-dependent mechanism

Human endogenous retrovirus W family envelope protein (ERVWE1) regulates macroautophagy activation and micromitophagy inhibition via NOXA1 in schizophrenia

The human endogenous retrovirus type W envelope glycoprotein (ERVWE1), located at chromosome 7q21-22, has been implicated in the pathophysiology of schizophrenia. Our previous studies have shown elevated ERVWE1 expression in schizophrenia patients. Growing evidence suggests that autophagy dysfunction contributes to schizophrenia, yet the relationship between ERVWE1 and autophagy remains unclear. In this study, bioinformatics analysis of the human prefrontal cortex RNA microarray dataset (GSE53987) revealed that differentially expressed genes were predominantly enriched in autophagy-related pathways. Clinical data further demonstrated that serum levels of microtubule-associated protein 1 light chain 3β (LC3B), a key marker of macroautophagy, were significantly elevated in schizophrenia patients compared to controls, and positively correlated with ERVWE1 expression. Cellular and molecular experiments suggested that ERVWE1 promoted macroautophagy by increasing the LC3B II/I ratio, enhancing autophagosome formation, and reducing sequestosome 1 (SQSTM1) expression via upregulation of NADPH oxidase activator 1 (NOXA1). Concurrently, NOXA1 downregulated the expression of key micromitophagy-related genes, including PTEN-induced kinase 1 (PINK1), Parkin RBR E3 ubiquitin-protein ligase (Parkin), and the pyruvate dehydrogenase E1 subunit α 1 (PDHA1). As a result, ERVWE1, via NOXA1, inhibited micromitophagy by suppressing the expression of PINK1, Parkin, and PDHA1, thereby leading to impaired production of mitochondrial-derived vesicles (MDVs). Mechanistically, ERVWE1 enhanced NOXA1 transcription by upregulating upstream transcription factor 2 (USF2). In conclusion, ERVWE1 promotes macroautophagy and inhibits micromitophagy through USF2-NOXA1 axis, providing novel mechanistic insight into the role autophagy dysregulation in schizophrenia. These findings suggest that targeting autophagy pathways may offer novel therapeutic strategies for schizophrenia treatment.

Neuropathogenesis of acute HIV: mechanisms, biomarkers, and therapeutic approaches

PURPOSE OF REVIEW

The neuropathogenesis of acute HIV leads to rapid central nervous system (CNS) involvement, characterized by early viral entry, immune activation, and the formation of viral reservoirs. Despite effective antiretroviral therapy (ART), these reservoirs persist, drive neuroinflammation and injury and lead to HIV-associated neurodegenerative disorders (HAND). This review provides an updated synthesis of the mechanisms in acute HIV neuropathogenesis, biomarkers of CNS injury and emerging therapeutic approaches. A deeper understanding of these mechanisms is critical for addressing persistent HAND in ART-treated individuals.

RECENT FINDINGS

Growing evidence now supports the principal role of infected CD4 + T cells in mediating HIV neuroinvasion alongside monocytes, resulting in seeding in perivascular macrophages, pericytes, and adjacent microglia and astrocytes. These reservoirs contribute to ongoing transcriptional activity and viral persistence despite antiretroviral therapy. Neuroinflammation, driven by activated microglia, astrocytes, inflammasomes, and neurotoxic viral proteins, disrupts neuronal homeostasis. Emerging therapies, including latency-reversing agents and transcription inhibitors, show promise in reducing neuroinflammation and reservoir activity.

SUMMARY

Understanding the mechanisms of HIV neuropathogenesis and reservoir persistence has significant implications for developing targeted therapies to mitigate HAND. Strategies to eliminate CNS reservoirs and reduce neuroinflammation should be prioritized to improve long-term cognitive outcomes in people with HIV.

Cofilin(s) and Mitochondria: Function Beyond Actin Dynamics

ADF/cofilins form a family of small, widely expressed actin-binding proteins, regulating actin dynamics in various cellular and physiological processes in all eukaryotes, from yeasts to animals. Changes in the expression of the ADF/cofilin family proteins have been demonstrated under various pathological conditions. The well-established role of cofilin in migration, invasion, epithelial-mesenchymal transition, apoptosis, resistance to radiotherapy and chemotherapy, immune escape, and transcriptional dysregulation in malignant tumors is primarily attributed to its actin-modifying activity. Moreover, drugs targeting this function of cofilin have been developed for cancer treatment. However, its multilevel regulation, highly diverse effects across various pathological conditions, and conflicting data on the functional consequences of altered cofilin expression have prompted us to explore additional roles of cofilin-beyond actin modulation-particularly its involvement in lipid metabolism and mitochondrial homeostasis. Here, we review recent data on the expression of ADF/cofilin family proteins in various pathologies, account for the mutations and post-translational modifications of these proteins and their functional consequences, dwell on the role of K63-type ubiquitination of cofilin for its involvement in lipid metabolism and mitochondrial homeostasis, more specifically, a process of mitochondrial division or mitofission, point out conflicting data in cofilin research, and describe prospects for future studies of cofilin functions.

RETRACTED ARTICLE: The protective effects of apelin-13 in HIV-1 tat- induced macrophage infiltration and BBB impairment

We, the Editors and Publisher of the journal Tissue Barriers, have retracted the following article:Cao, Q., Zeng, W., Nie, J., Ye, Y., & Chen, Y. (2024). The protective effects of apelin-13 in HIV-1 tat- induced macrophage infiltration and BBB impairment. Tissue Barriers. https://doi.org/10.1080/21688370.2024.2392361After publication, the corresponding author requested the withdrawal of the article because none of the listed authors had agreed to the publication of the article. When contacted for further information, only the corresponding author has responded. The corresponding author has provided proof of their affiliation and details of their current email address, which differs from the email address associated with the submission and publication of the article.As determining authorship is core to the integrity of published work, we are therefore retracting the article. The corresponding author listed in this publication has been informed.We have been informed in our decision-making by our editorial policies and the COPE guidelines.The retracted article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted'.

Inhibition of CXCR4: A perspective on miracle fruit seed for Alzheimer's disease treatment

Alzheimer's disease (AD) is the most prevalent type of dementia, and its causes are currently diverse and not fully understood. In a previous study, we discovered that short-term treatment with miracle fruit seed (MFS) had a therapeutic effect on AD model mice, however, the precise mechanism behind the effect remains unclear. In this research, we aimed to establish the efficacy and safety of long-term use of MFS in AD model mice. A variety of cytokines and chemokines have been implicated in the development of AD. Previous studies have validated a correlation between the expression levels of C-X-C chemokine receptor type 4 (CXCR4) and disease severity in AD. In this research, we observed an upregulation of CXCR4 expression in hippocampal tissues in the AD model group, which was then reversed after MFS treatment. Moreover, CXCR4 knockout led to improving cognitive function in AD model mice, and MFS showed the ability to regulate CXCR4 expression. Finally, our findings indicate that CXCR4 knockout and long-term MFS treatment produce comparable effects in treating AD model mice. In conclusion, this research demonstrates that therapeutic efficacy and safety of long-term use of MFS in AD model mice. MFS treatment and the subsequent reduction of CXCR4 expression exhibit a neuroprotective role in the brain, highlighting their potential as therapeutic targets for AD.

ROS Chronicles in HIV Infection: Genesis of Oxidative Stress, Associated Pathologies, and Therapeutic Strategies

Reactive oxygen species (ROS) are widely regarded as signaling molecules and play essential roles in various cellular processes, but when present in excess, they can lead to oxidative stress (OS). Growing evidence suggests that the OS plays a critical role in the pathogenesis of HIV infection and is associated with several comorbidities in HIV-infected individuals. ROS, generated both naturally during mitochondrial oxidative metabolism and as a response to various cellular processes, can trigger host antiviral responses but can also promote viral replication. While the multifaceted roles of ROS in HIV pathophysiology clearly need more investigation, this review paper unravels the mechanisms of OS generation in the context of HIV infections, offering insights into HIV viral protein-mediated and antiretroviral therapy-generated OS. Though the viral protein Tat is significantly attributed to the endogenous cellular increase in ROS post HIV infection, this paper sums up the contribution of other viral proteins in HIV-mediated elicitation of ROS. Given the investigations recognizing the significant role of ROS in the onset and progression of diverse pathologies, the paper also explores the critical function of ROS in the mediation of an of array of pathologies associated with HIV infection and retroviral therapy. HIV patients are observed with disruption to the antioxidant defense system, the antioxidant therapy is gaining focus as a potential therapeutic intervention and is well discussed. While ROS play a significant role in the HIV scenario, further exploratory studies are imperative to identifying alternative therapeutic strategies that could mitigate the toxicities and pathologies associated with ART-induced OS.

α-Synuclein triggers cofilin pathology and dendritic spine impairment via a PrPC-CCR5 dependent pathway

Cognitive dysfunction and dementia are critical symptoms of Lewy Body dementias (LBD). Specifically, alpha-synuclein (αSyn) accumulation in the hippocampus leading to synaptic dysfunction is linked to cognitive deficits in LBD. Here, we investigated the pathological impact of αSyn on hippocampal neurons. We report that either αSyn overexpression or αSyn pre-formed fibrils (PFFs) treatment triggers the formation of cofilin-actin rods, synapse disruptors, in cultured hippocampal neurons and in the hippocampus of synucleinopathy mouse models and of LBD patients. In vivo, cofilin pathology is present concomitantly with synaptic impairment and cognitive dysfunction. Rods generation prompted by αSyn involves the co-action of the cellular prion protein (PrPC) and the chemokine receptor 5 (CCR5). Importantly, we show that CCR5 inhibition, with a clinically relevant peptide antagonist, reverts dendritic spine impairment promoted by αSyn. Collectively, we detail the cellular and molecular mechanism through which αSyn disrupts hippocampal synaptic structure and we identify CCR5 as a novel therapeutic target to prevent synaptic impairment and cognitive dysfunction in LBD.

The chemokine receptor CCR5: multi-faceted hook for HIV-1

Chemokines are cytokines whose primary role is cellular activation and stimulation of leukocyte migration. They perform their various functions by interacting with G protein-coupled cell surface receptors (GPCRs) and are involved in the regulation of many biological processes such as apoptosis, proliferation, angiogenesis, hematopoiesis or organogenesis. They contribute to the maintenance of the homeostasis of lymphocytes and coordinate the function of the immune system. However, chemokines and their receptors are sometimes hijacked by some pathogens to infect the host organism. For a given chemokine receptor, there is a wide structural, organizational and conformational diversity. In this review, we describe the evidence for structural variety reported for the chemokine receptor CCR5, how this variability can be exploited by HIV-1 to infect its target cells and what therapeutic solutions are currently being developed to overcome this problem.

Chemokine Receptor Antagonists Prevent and Reverse Cofilin-Actin Rod Pathology and Protect Synapses in Cultured Rodent and Human iPSC-Derived Neurons

Synapse loss is the principal cause of cognitive decline in Alzheimer's disease (AD) and related disorders (ADRD). Synapse development depends on the intricate dynamics of the neuronal cytoskeleton. Cofilin, the major protein regulating actin dynamics, can be sequestered into cofilactin rods, intra-neurite bundles of cofilin-saturated actin filaments that can disrupt vesicular trafficking and cause synaptic loss. Rods are a brain pathology in human AD and mouse models of AD and ADRD. Eliminating rods is the focus of this paper. One pathway for rod formation is triggered in ~20% of rodent hippocampal neurons by disease-related factors (e.g., soluble oligomers of Amyloid-β (Aβ)) and requires cellular prion protein (PrPC), active NADPH oxidase (NOX), and cytokine/chemokine receptors (CCRs). FDA-approved antagonists of CXCR4 and CCR5 inhibit Aβ-induced rods in both rodent and human neurons with effective concentrations for 50% rod reduction (EC50) of 1-10 nM. Remarkably, two D-amino acid receptor-active peptides (RAP-103 and RAP-310) inhibit Aβ-induced rods with an EC50 of ~1 pM in mouse neurons and ~0.1 pM in human neurons. These peptides are analogs of D-Ala-Peptide T-Amide (DAPTA) and share a pentapeptide sequence (TTNYT) antagonistic to several CCR-dependent responses. RAP-103 does not inhibit neuritogenesis or outgrowth even at 1 µM, >106-fold above its EC50. N-terminal methylation, or D-Thr to D-Ser substitution, decreases the rod-inhibiting potency of RAP-103 by 103-fold, suggesting high target specificity. Neither RAP peptide inhibits neuronal rod formation induced by excitotoxic glutamate, but both inhibit rods induced in human neurons by several PrPC/NOX pathway activators (Aβ, HIV-gp120 protein, and IL-6). Significantly, RAP-103 completely protects against Aβ-induced loss of mature and developing synapses and, at 0.1 nM, reverses rods in both rodent and human neurons (T½ ~ 3 h) even in the continuous presence of Aβ. Thus, this orally available, brain-permeable peptide should be highly effective in reducing rod pathology in multifactorial neurological diseases with mixed proteinopathies acting through PrPC/NOX.

Characterization of a Human Neuronal Culture System for the Study of Cofilin-Actin Rod Pathology

Cofilactin rod pathology, which can initiate synapse loss, has been extensively studied in rodent neurons, hippocampal slices, and in vivo mouse models of human neurodegenerative diseases such as Alzheimer's disease (AD). In these systems, rod formation induced by disease-associated factors, such as soluble oligomers of Amyloid-β (Aβ) in AD, utilizes a pathway requiring cellular prion protein (PrPC), NADPH oxidase (NOX), and cytokine/chemokine receptors (CCR5 and/or CXCR4). However, rod pathways have not been systematically assessed in a human neuronal model. Here, we characterize glutamatergic neurons differentiated from human-induced pluripotent stem cells (iPSCs) for the formation of rods in response to activators of the PrPC-dependent pathway. Optimization of substratum, cell density, and use of glial-conditioned medium yielded a robust system for studying the development of Aβ-induced rods in the absence of glia, suggesting a cell-autonomous pathway. Rod induction in younger neurons requires ectopic expression of PrPC, but this dependency disappears by Day 55. The quantification of proteins within the rod-inducing pathway suggests that increased PrPC and CXCR4 expression may be factors in the doubling of the rod response to Aβ between Days 35 and 55. FDA-approved antagonists to CXCR4 and CCR5 inhibit the rod response. Rods were predominantly observed in dendrites, although severe cytoskeletal disruptions prevented the assignment of over 40% of the rods to either an axon or dendrite. In the absence of glia, a condition in which rods are more readily observed, neurons mature and fire action potentials but do not form functional synapses. However, PSD95-containing dendritic spines associate with axonal regions of pre-synaptic vesicles containing the glutamate transporter, VGLUT1. Thus, our results identified stem cell-derived neurons as a robust model for studying cofilactin rod formation in a human cellular environment and for developing effective therapeutic strategies for the treatment of dementias arising from multiple proteinopathies with different rod initiators.

The Impact of Neurotransmitters on the Neurobiology of Neurodegenerative Diseases

Neurodegenerative diseases affect millions of people worldwide. Neurodegenerative diseases result from progressive damage to nerve cells in the brain or peripheral nervous system connections that are essential for cognition, coordination, strength, sensation, and mobility. Dysfunction of these brain and nerve functions is associated with Alzheimer's disease, Parkinson's disease, Huntington's disease, Amyotrophic lateral sclerosis, and motor neuron disease. In addition to these, 50% of people living with HIV develop a spectrum of cognitive, motor, and/or mood problems collectively referred to as HIV-Associated Neurocognitive Disorders (HAND) despite the widespread use of a combination of antiretroviral therapies. Neuroinflammation and neurotransmitter systems have a pathological correlation and play a critical role in developing neurodegenerative diseases. Each of these diseases has a unique pattern of dysregulation of the neurotransmitter system, which has been attributed to different forms of cell-specific neuronal loss. In this review, we will focus on a discussion of the regulation of dopaminergic and cholinergic systems, which are more commonly disturbed in neurodegenerative disorders. Additionally, we will provide evidence for the hypothesis that disturbances in neurotransmission contribute to the neuronal loss observed in neurodegenerative disorders. Further, we will highlight the critical role of dopamine as a mediator of neuronal injury and loss in the context of NeuroHIV. This review will highlight the need to further investigate neurotransmission systems for their role in the etiology of neurodegenerative disorders.

HIV-1 envelope protein gp120 modulation of glutamate effects on cortical neuronal synapses: implications for HIV-1-associated neuropathogenesis

Despite the introduction of combined antiretroviral therapy (cART) HIV-1 virus persists in the brain in a latent or restricted manner and viral proteins, such as gp120, continue to play a significant disease-inciting role. Gp120 is known to interact with N-methyl-D-aspartate (NMDA) receptors (NMDARs) resulting in neuronal injury. Glutamate is the main excitatory neurotransmitter in the brain and plays an important role in cognitive function and dysregulation of excitatory synaptic transmission impairs neurocognition. It is our hypothesis that gp120 may alter synaptic function via modulating glutamate function from a physiological molecule to a pathophysiological substance. To test this hypothesis, we studied the modulatory effects of gp120 and glutamate on NMDAR-mediated spontaneous excitatory postsynaptic current (sEPSCNMDAR) and dynamic dendritic spine changes in rat cortical neuronal cultures. Our results revealed that gp120 and glutamate each, at low concentrations, had no significant effects on sEPSCNMDAR and dendritic spines, but increased sEPSCNMDAR frequency, decreased numbers of dendritic spines when tested in combination. The observed effects were blocked by either a CXCR4 blocker or an NMDAR antagonist, indicating the involvements of chemokine receptor CXCR4 and NMDARs in gp120 modulation of glutamate effects. These results may imply a potential mechanism for HIV-1-associated neuropathogenesis in the cART era.

Visualizing Cofilin-Actin Filaments by Immunofluorescence and CryoEM: Essential Steps for Observing Cofilactin in Cells

Fluorescence microscopy of cytoskeletal proteins in situ using immunolabeling, fluorescent reagents, or expression of tagged proteins has been a common practice for decades but often with too little regard for what might not be visualized. This is especially true for assembled filamentous actin (F-actin), for which binding of fluorescently labeled phalloidin is taken as the gold standard for its quantification even though it is well known that F-actin saturated with cofilin (cofilactin) binds neither fluorescently labeled phalloidin nor genetically encoded F-actin reporters, such as LifeAct. Here, using expressed fluorescent cofilactin reporters, we show that cofilactin is the major component of some actin-containing structures in both normal and stressed neurons and present various fixation, permeabilization, and cryo-preservation methods for optimizing its observation.

Identification of human immunodeficiency virus -1 E protein-targeting lead compounds by pharmacophore based screening

OBJECTIVES

To identify potential compounds by seeking the knowledge of molecular interactions between human immunodeficiency virus (HIV) glycoprotein (gp) 120 protein and anti-HIV drug (BMS-488043).

METHODS

This study is a computational structure-based drug design study, carried out at University of Taif, Saudi Arabia and African Genome Centre (AGC), Mohammed VI Polytechnic University, Benguerir, Morocco from January 2021 to March 2022. Initially, using the docked structure of gp120 with BMS-488043, a structure-based pharmacophore model was created. The generated model was utilized for virtual screening of the ZINC and ChemBridge database in order to identify hit compounds. To further assess the time-dependent stability of the selected complexes, computer simulation was performed.

RESULTS

From pharmacophore-based screening, 356 hits were obtained from both the database. The docking studies of the retrieved hit compounds reveal that all the compounds fit into the binding site of gp120. However, based on the significant interactions with the crucial residues and docking scores four compounds were suggested as potential hits. MD simulation of ChemBridge14695864 and ZINC06893293 in complex with gp120 suggested that both compounds significantly stabilized the receptor.

CONCLUSION

These findings could aid in the design of effective drugs against HIV by inhibiting the interaction between gp120 and CD4.

Cytoskeletal dysregulation and neurodegenerative disease: Formation, monitoring, and inhibition of cofilin-actin rods

The presence of atypical cytoskeletal dynamics, structures, and associated morphologies is a common theme uniting numerous diseases and developmental disorders. In particular, cytoskeletal dysregulation is a common cellular feature of Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. While the numerous activators and inhibitors of dysregulation present complexities for characterizing these elements as byproducts or initiators of the disease state, it is increasingly clear that a better understanding of these anomalies is critical for advancing the state of knowledge and plan of therapeutic attack. In this review, we focus on the hallmarks of cytoskeletal dysregulation that are associated with cofilin-linked actin regulation, with a particular emphasis on the formation, monitoring, and inhibition of cofilin-actin rods. We also review actin-associated proteins other than cofilin with links to cytoskeleton-associated neurodegenerative processes, recognizing that cofilin-actin rods comprise one strand of a vast web of interactions that occur as a result of cytoskeletal dysregulation. Our aim is to present a current perspective on cytoskeletal dysregulation, connecting recent developments in our understanding with emerging strategies for biosensing and biomimicry that will help shape future directions of the field.

The role of CCR5 in HIV-associated neurocognitive disorders

While combination antiretroviral therapy (cART) has successfully increased the lifespan of individuals infected with HIV, a significant portion of this population remains affected by HIV-associated neurocognitive disorder (HAND). C-C chemokine receptor 5 (CCR5) has been well studied in immune response and as a co-receptor for HIV infection. HIV-infected (HIV⁺) patients experienced mild to significant amelioration of cognitive function when treated with different CCR5 antagonists, including maraviroc and cenicriviroc. Consistent with clinical results, Ccr5 knockout or knockdown rescued cognitive deficits in HIV animal models, with mechanisms of reduced microgliosis and neuroinflammation. Pharmacologic inhibition of CCR5 directly improved cerebral and hippocampal neuronal plasticity and cognitive function. By summarizing the animal and human studies of CCR5 in HIV-associated cognitive deficits, this review aims to provide an overview of the mechanistic role of CCR5 in HAND pathophysiology. This review also discusses the addition of CCR5 antagonists, such as maraviroc, to cART for targeted prevention and treatment of cognitive impairments in patients infected with HIV.

Metabolic Reprogramming in HIV-Associated Neurocognitive Disorders

A significant number of patients infected with HIV-1 suffer from HIV-associated neurocognitive disorders (HAND) such as spatial memory impairments and learning disabilities (SMI-LD). SMI-LD is also observed in patients using combination antiretroviral therapy (cART). Our lab has demonstrated that the HIV-1 protein, gp120, promotes SMI-LD by altering mitochondrial functions and energy production. We have investigated cellular processes upstream of the mitochondrial functions and discovered that gp120 causes metabolic reprogramming. Effectively, the addition of gp120 protein to neuronal cells disrupted the glycolysis pathway at the pyruvate level. Looking for the players involved, we found that gp120 promotes increased expression of polypyrimidine tract binding protein 1 (PTBP1), causing the splicing of pyruvate kinase M (PKM) into PKM1 and PKM2. We have also shown that these events lead to the accumulation of advanced glycation end products (AGEs) and prevent the cleavage of pro-brain-derived neurotrophic factor (pro-BDNF) protein into mature brain-derived neurotrophic factor (BDNF). The accumulation of proBDNF results in signaling that increases the expression of the inducible cAMP early repressor (ICER) protein which then occupies the cAMP response element (CRE)-binding sites within the BDNF promoters II and IV, thus altering normal synaptic plasticity. We reversed these events by adding Tepp-46, which stabilizes the tetrameric form of PKM2. Therefore, we concluded that gp120 reprograms cellular metabolism, causing changes linked to disrupted memory in HIV-infected patients and that preventing the disruption of the metabolism presents a potential cure against HAND progression.

Cofilin and Actin Dynamics: Multiple Modes of Regulation and Their Impacts in Neuronal Development and Degeneration

Proteins of the actin depolymerizing factor (ADF)/cofilin family are ubiquitous among eukaryotes and are essential regulators of actin dynamics and function. Mammalian neurons express cofilin-1 as the major isoform, but ADF and cofilin-2 are also expressed. All isoforms bind preferentially and cooperatively along ADP-subunits in F-actin, affecting the filament helical rotation, and when either alone or when enhanced by other proteins, promotes filament severing and subunit turnover. Although self-regulating cofilin-mediated actin dynamics can drive motility without post-translational regulation, cells utilize many mechanisms to locally control cofilin, including cooperation/competition with other proteins. Newly identified post-translational modifications function with or are independent from the well-established phosphorylation of serine 3 and provide unexplored avenues for isoform specific regulation. Cofilin modulates actin transport and function in the nucleus as well as actin organization associated with mitochondrial fission and mitophagy. Under neuronal stress conditions, cofilin-saturated F-actin fragments can undergo oxidative cross-linking and bundle together to form cofilin-actin rods. Rods form in abundance within neurons around brain ischemic lesions and can be rapidly induced in neurites of most hippocampal and cortical neurons through energy depletion or glutamate-induced excitotoxicity. In ~20% of rodent hippocampal neurons, rods form more slowly in a receptor-mediated process triggered by factors intimately connected to disease-related dementias, e.g., amyloid-β in Alzheimer’s disease. This rod-inducing pathway requires a cellular prion protein, NADPH oxidase, and G-protein coupled receptors, e.g., CXCR4 and CCR5. Here, we will review many aspects of cofilin regulation and its contribution to synaptic loss and pathology of neurodegenerative diseases.

Alzheimer's-Like Pathology at the Crossroads of HIV-Associated Neurological Disorders

Despite the widespread success of combined antiretroviral therapy (cART) in suppressing viremia, the prevalence of human immunodeficiency virus (HIV)-associated neurological disorders (HAND) and associated comorbidities such as Alzheimer’s disease (AD)-like symptomatology is higher among people living with HIV. The pathophysiology of observed deficits in HAND is well understood. However, it has been suggested that it is exacerbated by aging. Epidemiological studies have suggested comparable concentrations of the toxic amyloid protein, amyloid-β42 (Aβ42), in the cerebrospinal fluid (CSF) of HAND patients and in the brains of patients with dementia of the Alzheimer’s type. Apart from abnormal amyloid-β (Aβ) metabolism in AD, a better understanding of the role of similar pathophysiologic processes in HAND could be of substantial value. The pathogenesis of HAND involves either the direct effects of the virus or the effect of viral proteins, such as Tat, Gp120, or Nef, as well as the effects of antiretrovirals on amyloid metabolism and tauopathy, leading, in turn, to synaptodendritic alterations and neuroinflammatory milieu in the brain. Additionally, there is a lack of knowledge regarding the causative or bystander role of Alzheimer’s-like pathology in HAND, which is a barrier to the development of therapeutics for HAND. This review attempts to highlight the cause–effect relationship of Alzheimer’s-like pathology with HAND, attempting to dissect the role of HIV-1, HIV viral proteins, and antiretrovirals in patient samples, animal models, and cell culture model systems. Biomarkers associated with Alzheimer’s-like pathology can serve as a tool to assess the neuronal injury in the brain and the associated cognitive deficits. Understanding the factors contributing to the AD-like pathology associated with HAND could set the stage for the future development of therapeutics aimed at abrogating the disease process.