- Browse by Subject
Browsing by Subject "Antiretroviral agents"
Now showing 1 - 5 of 5
Results Per Page
Sort Options
Item Dual regulation of voltage- and ligand-gated calcium channels by collapsin response mediator protein 2(2013-10-07) Brittain, Joel Matthew; Khanna, Rajesh; Cummins, Theodore R.; Oxford, G. S.; Quilliam, Lawrence; Thurmond, Debbie C.Synaptic transmission is coordinated by a litany of protein-protein interactions that rely on the proper localization and function of pre- and post-synaptic Ca2+ channels. The axonal guidance/specification collapsin response mediator protein-2 (CRMP-2) was identified as a potential partner of the pre-synaptic N-type voltage-gated Ca2+ channel (CaV2.2). CRMP-2 bound directly to CaV2.2 in two regions; the channel domain I-II intracellular loop and the distal C-terminus. Both proteins co-localized within presynaptic sites in hippocampal neurons. Overexpression in hippocampal neurons of a CRMP-2 protein fused to EGFP caused a significant increase in Ca2+ channel current density whereas lentivirus-mediated CRMP-2 knockdown abolished this effect. Cell surface biotinylation studies showed an increased number of CaV2.2 at the cell surface in CRMP-2–overexpressing neurons. Both activity- and CRMP-2-phosphoryation altered the interaction between CaV2.2 and CRMP-2. I identified a CRMP-2-derived peptide (called CBD3) that bound CaV2.2 and effectively disrupted the interaction between CaV2.2 and CRMP-2. CBD3 peptide fused to the HIV TAT protein (TAT-CBD3) decreased neuropeptide release from sensory neurons and excitatory synaptic transmission in dorsal horn neurons, and reversed neuropathic hypersensitivity produced by an antiretroviral drug. Unchecked Ca2+ influx via N-methyl-D-aspartate receptors (NMDARs) has been linked to activation of neurotoxic cascades culminating in cell death (i.e. excitotoxicity). CRMP-2 was suggested to affect NMDAR trafficking and possibly involved in neuronal survival following excitotoxicity. Based upon these studies, I hypothesized that a peptide from CRMP2 could preserve neurons in the face of excitotoxic challenges. Lentiviral–mediated CRMP2 knockdown or treatment with TAT-CBD3 blocked neuronal death following glutamate exposure likely via blunting toxicity from NMDAR-mediated delayed calcium deregulation. TAT-CBD3 induced internalization of the NMDAR subunit NR2B in dendritic spines without altering somal surface expression. TAT-CBD3 reduced NMDA-mediated Ca2+-influx and currents in cultured neurons. The presented work validates CRMP-2 as a novel modulator of pre- and post-synaptic Ca2+ channels and provides evidence that the TAT-CBD3 peptide could be useful as a potential therapeutic for both chronic neuropathic pain and excitotoxicity following stroke or other neuronal insults.Item Real-world use and outcomes of dolutegravir-containing antiretroviral therapy in HIV and tuberculosis co-infection: a site survey and cohort study in sub-Saharan Africa(Wiley, 2022) Romo, Matthew L.; Brazier, Ellen; Mahambou-Nsondé, Dominique; De Waal, Reneé; Sekaggya-Wiltshire, Christine; Chimbetete, Cleophas; Muyindike, Winnie R.; Murenzi, Gad; Kunzekwenyika, Cordelia; Tiendrebeogo, Thierry; Muhairwe, Josephine A.; Lelo, Patricia; Dzudie, Anastase; Twizere, Christelle; Rafael, Idiovino; Ezechi, Oliver C.; Diero, Lameck; Yotebieng, Marcel; Fenner, Lukas; Wools-Kaloustian, Kara K.; Shah, N. Sarita; Nash, Denis; International epidemiology Databases to Evaluate AIDS (IeDEA); Medicine, School of MedicineIntroduction: Dolutegravir is being scaled up globally as part of antiretroviral therapy (ART), but for people with HIV and tuberculosis co-infection, its use is complicated by a drug-drug interaction with rifampicin requiring an additional daily dose of dolutegravir. This represents a disadvantage over efavirenz, which does not have a major drug-drug interaction with rifampicin. We sought to describe HIV clinic practices for prescribing concomitant dolutegravir and rifampicin, and characterize virologic outcomes among patients with tuberculosis co-infection receiving dolutegravir or efavirenz. Methods: Within the four sub-Saharan Africa regions of the International epidemiology Databases to Evaluate AIDS consortium, we conducted a site survey (2021) and a cohort study (2015-2021). The cohort study used routine clinical data and included patients newly initiating or already receiving dolutegravir or efavirenz at the time of tuberculosis diagnosis. Patients were followed from tuberculosis diagnosis until viral suppression (<1000 copies/ml), a competing event (switching ART regimen; loss to program/death) or administrative censoring at 12 months. Results: In the survey, 86 of 90 (96%) HIV clinics in 18 countries reported prescribing dolutegravir to patients who were receiving rifampicin as part of tuberculosis treatment, with 77 (90%) reporting that they use twice-daily dosing of dolutegravir, of which 74 (96%) reported having 50 mg tablets available to accommodate twice-daily dosing. The cohort study included 3563 patients in 11 countries, with 67% newly or recently initiating ART. Among patients receiving dolutegravir (n = 465), the cumulative incidence of viral suppression was 58.9% (95% confidence interval [CI]: 54.3-63.3%), switching ART regimen was 4.1% (95% CI: 2.6-6.2%) and loss to program/death was 23.4% (95% CI: 19.7-27.4%). Patients receiving dolutegravir had improved viral suppression compared with patients receiving efavirenz who had a tuberculosis diagnosis before site dolutegravir availability (adjusted subdistribution hazard ratio [aSHR]: 1.47, 95% CI: 1.28-1.68) and after site dolutegravir availability (aSHR 1.28, 95% CI: 1.08-1.51). Conclusions: At a programmatic level, dolutegravir was being widely prescribed in sub-Saharan Africa for people with HIV and tuberculosis co-infection with a dose adjustment for the drug-drug interaction with rifampicin. Despite this more complex regimen, our cohort study revealed that dolutegravir did not negatively impact viral suppression.Item Sam68, Stress Granules, and translational control of HIV-1 nef mRNA(2009-06-23T21:33:16Z) Henao-Mejia, Jorge Alejandro; He, Johnny J.; Blum, Janice S.; Roman, Ann; Wek, Ronald C.More than 20 million people have died of AIDS since the early eighties, while nearly 34 millions are currently infected with the HIV. Anti-retroviral therapy (ART) directed at key viral enzymes has changed AIDS from uniformly fatal to a manageable chronic disease. However, ART-associated drug resistance and toxicity have posed a great challenge for long-term management of the disease and have called for development of new therapeutics. In this study, we focused on the viral factor Nef and the host factor Sam68. Nef is a major pathogenic viral determinant for HIV-1, and no therapeutics have been targeted to this factor. Sam68 is indispensible for HIV-1 propagation. We revealed that Sam68 variants were very potent in preventing Nef expression. We found that these effects were associated with their ability to form a macromolecular structure called stress granules (SG). In addition, we demonstrated that these variants bound to nef mRNA in a sequence-specific manner. Furthermore, we showed that these variants co-localized with nef mRNA in SG. Importantly, we validated these findings in the context of HIV-1 infection of its natural target cells and found significant loss of Nef function in these cells. Taken together, these results demonstrate that SG induction and nef mRNA sequestration account for translational suppression of Nef expression and offer a new strategy for development of anti-HIV therapeutics. Sam68 is implicated in a variety of other important cellular processes. Our findings that Sam68 variants were able to induce SG formation prompted us to investigate whether wild-type Sam68 was also recruited to SG. We found that Sam68 was increasingly recruited into SG under oxidative stress, and that its specific domains were involved. However, Sam68 knockdown had no effects on SG assembly, suggesting that Sam68 is not a constitutive component of SG assembly. Lastly, we demonstrated that Sam68 complexed with TIA-1, an essential SG component. Taken together, these results provide direct evidence for the first time that Sam68 is recruited into SG through complexing with TIA-1, and suggest that SG recruitment of Sam68 and ensuing changes in Sam68 physiological functions are part of the host response to external stressful conditions.Item Transfer of intracellular HIV Nef to endothelium causes endothelial dysfunction(2014) Wang, Ting; Pelus, Louis; Clauss, Matthias A.; Yu, Andy; Dent, Alexander L.; Wek, Ronald C.With effective antiretroviral therapy (ART), cardiovascular diseases (CVD), are emerging as a major cause of morbidity and death in the aging population with HIV infection. Although this increase in CVD could be partially explained by the toxic effects of combined anti-retroviral therapy (ART), more recently, HIV infection has emerged as an independent risk factor for CVD. However, it is unclear how HIV can contribute to CVD in patients on ART, when viral titers are low or non-detectable. Here, we provide several lines of evidence that HIV-Nef, produced in infected cells even when virus production is halted by ART, can lead to endothelial activation and dysfunction, and thus may be involved in CVD. We demonstrate that HIV-infected T cell-induced endothelial cell activation requires direct contact as well as functional HIV-Nef. Nef protein from either HIV-infected or Nef-transfected T cells rapidly transfers to endothelial cells while inducing nanotube-like conduits connecting T cells to endothelial cells. This transfer or transfection of endothelial cells results in endothelial apoptosis, ROS generation and release of monocyte attractant protein-1 (MCP-1). A Nef SH3 binding site mutant abolishes Nef-induced apoptosis and ROS formation and reduces MCP-1 production in endothelial cells, suggesting that the Nef SH3 binding site is critical for Nef effects on endothelial cells. Nef induces apoptosis of endothelial cells through both NADPH oxidase- and ROS-dependent mechanisms, while Nef-induced MCP-1 production is NF-kB dependent. Importantly, Nef can be found in CD4 positive and bystander circulating blood cells in patients receiving virally suppressive ART, and in the endothelium of chimeric SIV-infected macaques. Together, these data indicate that Nef could exert pro-atherogenic effects on the endothelium even when HIV infection is controlled and that inhibition of Nef-associated pathways may be promising new therapeutic targets for reducing the risk for cardiovascular disease in the HIV-infected population.Item Viral Load Status Before Switching to Dolutegravir-Containing Antiretroviral Therapy and Associations With Human Immunodeficiency Virus Treatment Outcomes in Sub-Saharan Africa(Oxford University Press, 2022) Romo, Matthew L.; Edwards, Jessie K.; Semeere, Aggrey S.; Musick, Beverly S.; Urassa, Mark; Odhiambo, Francesca; Diero, Lameck; Kasozi, Charles; Murenzi, Gad; Lelo, Patricia; Wyka, Katarzyna; Kelvin, Elizabeth A.; Sohn, Annette H.; Wools-Kaloustian, Kara K.; Nash, Denis; International epidemiology Databases to Evaluate AIDS (IeDEA); Biostatistics, School of Public HealthBackground: Dolutegravir is being rolled out globally as part of preferred antiretroviral therapy (ART) regimens, including among treatment-experienced patients. The role of viral load (VL) testing before switching patients already on ART to a dolutegravir-containing regimen is less clear in real-world settings. Methods: We included patients from the International epidemiology Databases to Evaluate AIDS consortium who switched from a nevirapine- or efavirenz-containing regimen to one with dolutegravir. We used multivariable cause-specific hazards regression to estimate the association of the most recent VL test in the 12 months before switching with subsequent outcomes. Results: We included 36 393 patients at 37 sites in 5 countries (Democratic Republic of the Congo, Kenya, Rwanda, Tanzania, Uganda) who switched to dolutegravir from July 2017 through February 2020, with a median follow-up of approximately 11 months. Compared with those who switched with a VL <200 copies/mL, patients without a recent VL test or with a preswitch VL ≥1000 copies/mL had significantly increased hazards of an incident VL ≥1000 copies/mL (adjusted hazard ratio [aHR], 2.89; 95% confidence interval [CI], 1.99-4.19 and aHR, 6.60; 95% CI, 4.36-9.99, respectively) and pulmonary tuberculosis or a World Health Organization clinical stage 4 event (aHR, 4.78; 95% CI, 2.77-8.24 and aHR, 13.97; 95% CI, 6.62-29.50, respectively). Conclusions: A VL test before switching to dolutegravir may help identify patients who need additional clinical monitoring and/or adherence support. Further surveillance of patients who switched to dolutegravir with an unknown or unsuppressed VL is needed.