HIV-1 Gp120 Protein Research Articles

Curcumin Protects Microglia and Primary Rat Cortical Neurons against HIV-1 gp120-Mediated Inflammation and Apoptosis

Curcumin is a molecule found in turmeric root that has anti-inflammatory, antioxidant, and anti-tumor properties and has been widely used as both an herbal drug and a food additive to treat or prevent neurodegenerative diseases. To explore whether curcumin is able to ameliorate HIV-1-associated neurotoxicity, we treated a murine microglial cell line (N9) and primary rat cortical neurons with curcumin in the presence or absence of neurotoxic HIV-1 gp120 (V3 loop) protein. We found that HIV-1 gp120 profoundly induced N9 cells to produce reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1). HIV-1 gp120 also induced apoptosis of primary rat cortical neurons. Curcumin exerted a powerful inhibitory effect against HIV-1 gp120-induced neuronal damage, reducing the production of ROS, TNF-α and MCP-1 by N9 cells and inhibiting apoptosis of primary rat cortical neurons. Curcumin may exert its biological activities through inhibition of the delayed rectification and transient outward potassium (K+) current, as curcumin effectively reduced HIV-1 gp120-mediated elevation of the delayed rectification and transient outward K+ channel current in neurons. We conclude that HIV-1 gp120 increases ROS, TNF-α and MCP-1 production in microglia, and induces cortical neuron apoptosis by affecting the delayed rectification and transient outward K+ channel current. Curcumin reduces production of ROS and inflammatory mediators in HIV-1-gp120-stimulated microglia, and protects cortical neurons against HIV-1-mediated apoptosis, most likely through inhibition of HIV-1 gp120-induced elevation of the delayed rectification and transient outward K+ current.

The depolymerized fucosylated chondroitin sulfate from sea cucumber potently inhibits HIV replication via interfering with virus entry

Fucosylated chondroitin sulfate (FuCS-1) is a nontoxic and water-soluble depolymerized glycosaminoglycan obtained from the sea cucumber Thelenota ananas. Anti-HIV activities of FuCS-1 were evaluated in the present study. FuCS-1 was effective in blocking laboratory strain HIV-1IIIB entry and replication (4.26μg/mL and 0.73μg/mL, respectively), and inhibiting infection by clinic isolate HIV-1KM018 and HIV-1TC-2 (23.75μg/mL and 31.86μg/mL, respectively) as well as suppressing HIV-1 drug-resistant virus. It also inhibited HIV-2ROD and HIV-2CBL-20 replication (100μg/mL). Notably, FuCS-1 showed highly effective antiviral activity against T-20-resistant strains (EC50 values ranging from 0.76μg/mL to 1.13μg/mL). Further studies indicated that FuCS-1 can potently bind the recombinant HIV-1 gp120 protein, but no inhibition of recombinant HIV-1 reverse transcriptase was observed. In conclusion, FuCS-1 inhibited several strains of HIV-1 replication with different potencies. These results suggest that FuCS-1 may possess great potential to be further developed as novel HIV-1 entry inhibitor for treatment of HIV/AIDS patients, particularly for those infected by T-20-resistant variants.

T-Cell Signaling in HIV-1 Infection

HIV exploits the T-cell signaling network to gain access to downstream cellular components, which serves as effective tools to break the cellular barriers. Multiple host factors and their interaction with viral proteins contribute to the complexity of HIV-1 pathogenesis and disease progression. HIV-1 proteins gp120, Nef, Tat and Vpr alter the T-cell signaling pathways by activating multiple transcription factors including NF-ĸB, Sp1 and AP-1. HIV-1 evades the immune system by developing a multi-pronged strategy. Additionally, HIV-1 encoded proteins influence the apoptosis in the host cell favoring or blocking T-cell apoptosis. Thus, T-cell signaling hijacked by viral proteins accounts for both viral persistence and immune suppression during HIV-1 infection. Here, we summarize past and present studies on HIV-1 T-cell signaling with special focus on the possible role of T cells in facilitating viral infection and pathogenesis

Curcumin protects microglia and primary cortical neurons against HIV-mediated inflammation and apoptosis (P6181)

Abstract Curcumin is a substance in turmeric root with anti-inflammatory, antioxidant, and anti-tumor properties, and has been widely used both as an herbal drug and a food additive to treat or prevent neurodisorders. To explore whether curcumin is able to treat HIV-associated neurocognitive disorders (HAND), we treated murine microglial cell line (N9) and primary rat cortical neurons with curcumin in the presence and absence of HIV gp120 (V3 loop) protein. We found that HIV gp120 profoundly induced N9 cells to produce reactive oxygen species (ROS), tumor necrosis factor-α (TNF-α) and monocyte chemoattractant protein-1 (MCP-1). HIV-1 gp120 also induced apoptosis of primary rat cortical neurons. Curcumin exerted powerful inhibitory effect against gp120-induced neuronal damage, reducing production of ROS, TNF-α and MCP-1 by N9 cells, and inhibiting apoptosis of primary rat cortical neurons. Curcumin may exert its biological activities through inhibition of gp120-mediated rectification and transient outward potassium current, as curcumin effectively reduced gp120-mediated elevation of potassium channel current of neurons. Conclusions: HIV gp120 increases ROS, TNF-α and MCP-1 production in microglia, and induces cortical neuron apoptosis by affecting the voltage-gated potassium channel current. Curcumin protects microglia and cortical neurons against HIV-mediated inflammation and apoptosis, probably through inhibition of gp120-induced elevation of the voltage-gated potassium current.

HIV-1 Gp120 Protein Downregulates Nef Induced IL-6 Release in Immature Dentritic Cells through Interplay of DC-SIGN

HIV-1 replication is a tightly controlled mechanism which demands the interplay of host as well as viral factors. Both gp120 (envelope glycoprotein) and Nef (regulatory protein) have been correlated with the development of AIDS disease in independent studies. In this context, the ability of HIV-1 to utilize immature dentritic cells for transfer of virus is pivotal for early pathogenesis. The presence of C-type lectins on dendritic cells (DCs) like DC-SIGN, are crucial in inducing antiviral immunity to HIV-1. Both gp120 and Nef induce the release of cytokines leading to multiple effects of viral pathogenesis. Our study elucidated for the first time the cross-talk of the signaling mechanism of these two viral proteins in immature monocyte derived dentritic cells (immDCs). Further, gp120 was found to downregulate the IL-6 release by Nef, depending on the interaction with DC-SIGN. A cascade of signaling followed thereafter, including the activation of SOCS-3, to mediate the diminishing effect of gp120. Our results also revealed that the anti-apoptotic signals emanated from Nef was put to halt by gp120 through inhibition of Nef induced STAT3. Thus our results implicate that the signaling generated by gp120 and Nef, undergoes a switch-over mechanism that significantly contributes to the pathogenesis of HIV-1 and widens our view towards the approach on battling the viral infection.

46. HIV-induced epithelial–mesenchymal transition in mucosal epithelium facilitates HPV paracellular penetration

Background The incidence of human papillomavirus (HPV)-associated epithelial lesions in HIV-infected individuals is substantially higher than in HIV-negative individuals. HIV may increase the risk of mucosal HPV infection by induction of an epithelial–mesenchymal transition (EMT) phenotype that leads to reduced epithelial barrier functions. Methods: To model the effect of EMT on HPV entry, we used oral epithelial biopsies, and oral and anal keratinocytes from HIV-infected and HIV-uninfected individuals. EMT was defined as loss of adherens and tight junctions, and induction of vimentin expression. To study epithelial HPV entry we used HPV-16 pseudovirions (PsVs) containing a plasmid expressing red fluorescent protein (RFP). PsV penetration was evaluated using confocal microscopy to detect RFP-generated fluorescence. Results: Compared with oral epithelia from HIV-uninfected individuals, oral epithelia from HIV-infected individuals had reduced adherens and tight junctions and expressed vimentin. Keratinocytes isolated from oral and anal tissues of HIV-infected individuals also showed loss of E-cadherin and induction of vimentin expression. Exposure of oral epithelial cells from HIV-uninfected individuals to HIV and HIV tat, gp120, and nef proteins induced EMT with reduced cell junctions and epithelial polarity, and allowed paracellular passage of HPV-16 PsV. Oral mucosal epithelial tissues treated with HIV tat and gp120 also lost tight junctions and allowed PsV paracellular penetration, leading to PsV entry into basal/parabasal cells. Conclusions: HIV-associated EMT in oral epithelia, and oral and anal keratinocytes leads to impaired barrier function. This facilitates entry of HPV/PsV into basal/parabasal cells, and may contribute to the increased incidence of HPV-associated malignancy in HIV-infected individuals.

Probing interactions of the HIV protein GP120 with lipids and CD4 receptors

HIV viral protein interactions with cellular receptors are vital to the infection process. It is in this context that the HIV GP120 viral envelope protein interactions with lipid bilayers and CD4 receptors have been studied. It was demonstrated that the GP120 protein “sinks” into the lipid bilayer over time, a significant ability when considering its biological role. GP120 can also assemble into larger structures on lipid bilayers and forms unusual micron scale aggregates when preformed complexes are deposited on mica. It is possible to distinguish individual GP120/CD4 complexes when the receptor is reconstituted into the lipid bilayer with the force required to unfold the complex greater than the force required to unfold either of the individual components.

What mAbs Tell Us about Shapes: Multiple Roads Lead to Rome

In this issue of Immunity, Liao etal. (2013) utilize monoclonal antibodies isolated from RV144 vaccinees to gain key insights into the structural vulnerabilities of the V1-V2 loops of HIV gp120 protein and how they might be associated with vaccine efficacy.

Endothelial dysfunction, arterial stiffening, and intima-media thickening in large arteries from HIV-1 transgenic mice.

HIV patients on highly active antiretroviral therapy (HAART) exhibit elevated incidence of cardiovascular disease (CVD), including a higher risk of myocardial infarction and prevalence of atherosclerotic lesions, as well as increases in markers of subclinical atherosclerosis including increased carotid artery intima-media thickness (c-IMT), increased arterial stiffness, and impaired flow-mediated dilation. Both HAART and HIV-infection are independent risk factors for atherosclerosis and myocardial infarction. Studies implicate the HIV proteins tat, gp120, vpu, and nef in early on-set atherosclerosis. The objective of this study was to quantify the role of expression of HIV-1 proteins on the vascular function, biomechanics, and geometry of common carotid arteries and aortas. This study employed NL4-3Δ gag/pol transgenic mice (HIV-Tg), which contain the genetic sequence for the HIV-1 proteins env, tat, nef, rev, vif, vpr, and vpu but lacks the gag and pol genes and reports that HIV-Tg mice have impaired aortic endothelial function, increased c-IMT, and increased arterial stiffness. Further, HIV-Tg arteries show decreased elastin content, increased cathepsin K and cathepsin S activity, and increased mechanical residual stress. Thus, mice that express HIV proteins exhibit pre-clinical markers of atherosclerosis and these markers correlate with changes in markers of vascular remodeling. These findings are consistent with the hypothesis that HIV-proteins, independent of HAART treatment or HIV infection, could play a role in of the development of CVD.

Catechins protect neurons against mitochondrial toxins and HIV proteins via activation of the BDNF pathway.

Currently, there is no effective treatment for neurological complications of infection with the human immunodeficiency virus that persists despite the use of combination antiretroviral therapy. A medium throughput assay was developed for screening neuroprotective compounds using primary mixed neuronal cells and mitochondrial toxin 3-nitropropionic acid. Using this assay, a library of 2,000 compounds was screened. Out of 256 compounds that showed variable degrees of neuroprotection, nine were related to epicatechin, a monomeric flavonoid found in cocoa and green tea leaves that readily crosses the blood-brain barrier. Hence, catechin, epicatechin, and the related compound, epigallocatechin gallate (EGCG) were further screened for their neuroprotective properties against HIV proteins Tat and gp120, and compared to those of resveratrol. Epicatechin and EGCG targets the brain-derived neurotrophic factor (BDNF) and its precursor proBDNF signaling pathways, normalizing both Tat-mediated increases in proapoptotic proBDNF and concomitant Tat-mediated decreases in the mature BDNF protein in hippocampal neurons. Epicatechin and epigallocatechin gallate were more potent than catechin or resveratrol as neuroprotectants. Due to its simpler structure and more efficient blood-brain barrier penetration properties, epicatechin might be the best therapeutic candidate for neurodegenerative diseases including HIV-associated neurocognitive disorders where oxidative stress is an important pathophysiological mechanism.

Anti-HIV activity of semisynthetic derivatives of andrographolide and computational study of HIV-1 gp120 protein binding

Andrographolide, a diterpene lactone of the Andrographis paniculata, displays anti-HIV activity in vitro. A series of andrographolide derivatives have been synthesized and evaluated for their anti-HIV activity in a cell-free virus infectivity assay using TZM-bl cells. As compared to andrographolide, 3-nitrobenzylidene derivative 6 showed higher in vitro anti-HIV activity, whereas 2′,6′-dichloro-nicotinoyl ester derivative 9 showed higher Therapeutic Index. The andrographolide and its derivatives, 6 and 9, inhibited gp120-mediated cell fusion of HL2/3 cells (expressing gp120 on its surface) with TZM-bl cells (expressing CD4 and co-receptors CCR5 & CXCR4). Further, computational studies revealed that these molecules bind to the important residues of V3 loop of gp120. These results suggest that andrographolide derivatives may be promising candidates for prevention of HIV infection.

Structural elements of primary CCR5-using HIV-1 gp120 proteins influencing sensitivity and resistance to the broadly neutralizing monoclonal antibody b12

Structure-guided approaches to HIV-1 vaccine design depend on knowledge of the presentation of neutralizing epitopes on gp120, such as the epitope for the broadly neutralizing mAb b12. Here, we characterized predicted three-dimensional structures of functionally diverse gp120 proteins in their b12-bound conformation, to better understand the gp120 determinants that expose or occlude the b12 epitope. Mapping the gp120–b12 binding interface identified amino acid polymorphisms within the C2, C3, C4 and V5 regions of gp120 associated with augmented b12 binding, and importantly, identified residues in the b12-exclusive binding domain of gp120 that are important for b12 neutralization resistance. Structural studies suggest that these b12 resistance variants promote reduced conformational flexibility in the b12 recognition site, which we show involves structural alterations within the gp120 CD4 binding loop and the V4 loop. Together, our studies provide new mechanistic insights into the gp120 determinants influencing sensitivity and resistance to HIV-1 neutralization by b12.

Human Immunodeficiency Virus Type 1 Alters Brain-Derived Neurotrophic Factor Processing in Neurons

The molecular mechanisms leading to synaptic simplification and neuronal apoptosis in human immunodeficiency virus type 1 (HIV-1)-positive subjects are unknown. The HIV protein gp120 reduced the length of neuronal processes similarly to the proneurotrophin pro-brain-derived neurotrophic factor (proBDNF). Intriguingly, the effects of both proBDNF and gp120 were blocked by inhibitors of the p75 neurotrophin receptor, suggesting that proBDNF and gp120 share a similar mechanism of neurotoxicity. Therefore, we tested the hypothesis that gp120 affects the release of proBDNF. Using rat primary neurons, we observed that gp120 promotes a time-dependent intracellular and extracellular accumulation of proBDNF concomitantly with a decrease in mature BDNF. A similar imbalance in the ratio proBDNF/mature BDNF was confirmed in postmortem brains of HIV-positive subjects cognitively impaired and motor impaired. Therefore, it is conceivable to formulate the hypothesis that HIV neurotoxicity includes a gp120-mediated alteration of BDNF processing. To determine the cellular mechanism whereby gp120 produces an accumulation of proBDNF, we examined the levels of intracellular and extracellular enzymes that proteolytically cleave proBDNF furin and tissue plasminogen, respectively. In rat neurons exposed to gp120, intracellular furin levels decreased before cell death, whereas tissue plasminogen changed only during apoptosis. Our data suggest that HIV, through gp120, reduces proBDNF processing by affecting furin levels, and therefore causes an altered balance between antiapoptotic and proapoptotic neurotrophins. Our studies identify a new mechanism that may explain how HIV promotes neuronal injury.

In silico directed mutagenesis using software for glycosylation sites prediction as a new step in antigen design

Normal 0 false false false /* Style Definitions */ table.MsoNormalTable {mso-style-name:Обычная таблица; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:Times New Roman; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;} In silico directed mutagenesis with the aim to estimate consequences of mutational pressure on number of N- and O-glycosylation sites has been proposed as an important step in antigen design. Using this kind of methodology one is able to estimate probabilities at which N- and O-glycosylation sites can be destroyed and created due to one-step missense mutations in the subsequent gene. Mutational AT-pressure has been simulated in the region of env gene coding for HIV1 gp120. Consequences of 741 amino acid substitutions have been predicted with the help of NetNGlyc 1.0 and NetOGlyc 3.1 software. The probability of O-glycosylation site destruction (2.16%) in HIV1 gp120 protein due to a single missense GC to AT mutation in env gene is higher than the probability of a new site creation (0.40%). The probability of N-glycosylation site destruction in HIV1 gp120 protein is equal to the probability of its creation (5.53%), while the number of N-glycosylation sites which can be created due to a single missense GC to AT mutation in env gene is 1.27 times higher than the number of N-glycosylation sites which can be destroyed.

Accumulation of nuclear and mitochondrial DNA damage in the frontal cortex cells of patients with HIV-associated neurocognitive disorders

Oxidative stress has been suggested to play a key role in the neuropathogenesis of HIV infection. HIV proteins (gp120, Tat) and proinflammatory cytokines can trigger the production of reactive oxygen species (ROS), resulting in DNA and RNA lesions. Among all the lesions induced by ROS, one of the most abundant lesions in DNA and RNA is 8-hydroxydeoxyguanosine (8-oxoG). Here, we studied accumulated DNA oxidative damage induced by ROS in the central nervous system (CNS) in tissue from neuro-AIDS patients. The frontal cortex of autopsy tissue from HIV-1 infected patients was adopted for analysis for HIV-1 subtype, nuclear and mitochondrial DNA lesions by immunofluorescence staining, qPCR and sequencing of PCR cloning. This study provides evidence that HIV infection in the CNS leads to nuclear and mitochondrial genomic DNA damage in the brain. High level of nuclear and mtDNA 8-oxoG damage were identified in the cortex autopsy tissue of HAND patients. Increased accumulation of mtDNA mutations and depletion occurs in brain tissue in a subset of HAND cases, and is significantly different from that observed in control cases. These findings suggest that higher level of ROS in the CNS of HAND patients would contribute to the HIV induced neuro-inflammation and apoptosis of neuronal and glial cells.

Identification and Characterization of an Immunogenic Hybrid Epitope Formed by both HIV gp120 and Human CD4 Proteins

Identification and Characterization of an Immunogenic Hybrid Epitope Formed by both HIV gp120 and Human CD4 Proteins

Cloning and eukaryotic expression of HIV-1B gp120 genes from a patient with AIDS dementia complex

To clone and express the HIV-1B gp120 genes isolated at different organizations from a patient died of AIDS dementia complex (ADC) in eukaryotic cells. Using the genomic DNA isolated from peripheral lymphnodes, choroid plexus and occipital white matter from a patient died of ADC as the template, HIV-1B gp120 gene was amplified with PCR. After sequenced, HIV-1B gp120 was inserted into pcDNA3.1 (+) and recombinant expressing vector gp120/pcDNA3.1 (+) was constructed succeffuly confirming with sequencing. Then expressing vector was transfected into eukaryotic cells U87 using liposome transfection and expression of HIV-1B gp120 gene was assayed with indirect immunofluorescence. HIV-1B gp120 genes isolated from peripheral lymphnodes, choroid plexus and occipital white matter of the ADC patient were successfully cloned and recombinant expressing vector gp120/pcDNA3; 1 (+) could express envelope glycoprotein HIV-1B gp120 in U87 cells. All the HIV-1B gp120 gene isolated at the different organizations of the same ADC patient could express in U87 cells, which may supply a valuable basis for studying the neurotoxicity and neurotoxic mechanism of HIV-1 gp120 protein.

The correlation between pain‐related behaviour and spinal microgliosis in four distinct models of peripheral neuropathy

Peripheral nerve injury is associated with a spinal microglial response that has been correlated with the development of behaviours reflective of neuropathic pain. To examine whether this phenomenon is generalizable to neuropathic pain of non-traumatic aetiology, this study investigated the association between spinal microgliosis and behavioural measures of neuropathic hypersensitivity and pain-related anxiety behaviour in four distinct rat models of peripheral neuropathic pain. These were traumatic neuropathy [L5 spinal nerve transection (SNT)], HIV-related neuropathies (either treatment with the antiretroviral drug Zalcitabine (ddC) or combination of perineural exposure to the HIV-gp120 protein and ddC treatment) and varicella zoster virus (VZV) infection. Persistent mechanical hypersensitivity developed in all 'neuropathic' rats. However, spinal microgliosis, as measured by increased CD11b/c immunohistochemical staining and increased numbers of cells expressing CD11b measured by flow cytometry, was evident in the SNT and to a lesser extent in the HIV neuropathy models but not the VZV model. These results suggest that behavioural hypersensitivity and thigmotaxis can only be linked to a microglial response in certain models of neuropathy.

Comparison of antibodies and carbohydrates to target vaccines to human dendritic cells via DC-SIGN

Vaccine efficacy is improved upon specific delivery to professional antigen (Ag) presenting cells, such as dendritic cells (DCs). Antigenicity and adjuvanticity of vaccine components can be enhanced by encapsulation within nanoparticle (NP) vaccine carriers that are targeted to the human DC-specific C-type lectin receptor DC-SIGN. Here we used two strategies to target vaccines components to DC-SIGN: 1) carbohydrates as natural receptor ligands and 2) receptor-specific antibodies (Abs). To determine the optimal targeting strategy, we coated NP vaccines harboring MHC class I or II-restricted Ags and the TLR ligands (TLRLs) poly I:C and resiquimod with either the DC-SIGN ligands Lewis-X (Lex), mannosylated lipoarabinomannan (ManLAM), glycosylated HIV protein gp120, or three distinct DC-SIGN Abs. Although, because of their lower MW, surface coating of NP vaccines with carbohydrates resulted in a higher number of surface molecules per NP than coating with Abs, NP vaccines carrying Abs were more effectively bound and internalized by human DCs than carriers harboring Lex, ManLAM or gp120. Furthermore, NP vaccines harboring TLRLs triggered significant induction of DC maturation markers when compared to those without TLRLs, irrespective of the targeting moiety. Ab- and gp120-mediated targeting induced equally high levels of proinflammatory cytokines and increased presentation of the MHC class I-restricted epitope. By contrast, presentation of the MHC class II-restricted epitope was more efficient upon Ab-mediated targeting than when using gp120, Lex or ManLAM. From these findings we conclude that receptor-specific Abs are more effective than carbohydrates for DC-targeted vaccination strategies.

Glycosylation Assists Binding of HIV Protein gp120 to Human CD4 Receptor

The role of glycosylation of proteins on its binding affinity is not well understood. Even a monosaccharide (magenta) placed at a glycosylation site can significantly enhance binding of peptides to their receptor. If glycosylated, an HIV protein binds stronger and faster to its primary receptors on human cells.