The RNA-Binding Protein, Polypyrimidine Tract-Binding Protein 1 (PTBP1) Is a Key Regulator of CD4 T Cell Activation

We have previously shown that the RNA binding protein, polypyrimidine tract-binding protein (PTBP1) plays a critical role in regulating the expression of CD40L in activated CD4 T cells. This is achieved mechanistically through message stabilization at late times of activation as well as by altered distribution of CD40L mRNA within distinct cellular compartments. PTBP1 has been implicated in many different processes, however whether PTBP1 plays a broader role in CD4 T cell activation is not known. To examine this question, experiments were designed to introduce shRNA into primary human CD4 T cells to achieve decreased, but not complete ablation of PTBP1 expression. Analyses of shPTB-expressing CD4 T cells revealed multiple processes including cell proliferation, activation-induced cell death and expression of activation markers and cytokines that were regulated in part by PTBP1 expression. Although there was an overall decrease in the steady-state level of several activation genes, only IL-2 and CD40L appeared to be regulated by PTBP1 at the level of RNA decay suggesting that PTBP1 is critical at different regulatory steps of expression that is gene-specific. Importantly, even though the IL-2 protein levels were reduced in cells with lowered PTBP1, the steady-state level of IL-2 mRNA was significantly higher in these cells suggesting a block at the translational level. Evaluation of T cell activation in shPTB-expressing T cells revealed that PTBP1 was linked primarily to the activation of the PLCγ1/ERK1/2 and the NF-κB pathways. Overall, our results reveal the importance of this critical RNA binding protein in multiple steps of T cell activation.

HIV-1 Envelope Protein gp120 Promotes Proliferation and the Activation of Glycolysis in Glioma Cell

Patients infected with human immunodeficiency virus (HIV) are more prone to developing cancers, including glioblastomas (GBMs). The median survival for HIV positive GBM patients is significantly shorter than for those who are uninfected, despite the fact that they receive the same treatments. The nature of the GBM–HIV association remains poorly understood. In this study, we analyzed the effect of the HIV envelope glycoprotein gp120 on GBM cell proliferation. Specifically, we performed cell cycle, western blot, protein synthesis and metabolomics analysis as well as ATP production and oxygen consumption assays to evaluate proliferation and metabolic pathways in primary human glioma cell line, U87, A172 cells and in the HIVgp120tg/GL261 mouse model. Glioma cells treated with gp120 (100 ng/mL for 7–10 days) showed higher proliferation rates and upregulation in the expression of enolase 2, hexokinase and glyceraldehyde-3-phosphate dehydrogenase when compared to untreated cells. Furthermore, we detected an increase in the activity of pyruvate kinase and a higher glycolytic index in gp120 treated cells. Gp120 treated GBM cells also showed heightened lipid and protein synthesis. Overall, we demonstrate that in glioma cells, the HIV envelope glycoprotein promotes proliferation and activation of glycolysis resulting in increased protein and lipid synthesis.

c-Rel deficiency increases caspase-4 expression and leads to ER stress and necrosis in EBV-transformed cells

LMP1-mediated activation of nuclear factor of kappaB (NF-κB) is critical for the ligand independent proliferation and cell survival of in vitro EBV-transformed lymphoblastoid cell lines (LCLs). Previous experiments revealed that a majority of LMP1-dependent responses are regulated by NF-κB. However, the extent that individual NF-κB family members are required for these responses, in particular, c-Rel, whose expression is restricted to mature hematopoietic cells, remains unclear. Here we report that low c-Rel expression in LCLs derived from a patient with hyper-IgM syndrome (Pt1), resulted in defects in proliferation and cell survival. In contrast to studies that associated loss of NF-κB with increased apoptosis, Pt1 LCLs failed to initiate apoptosis and alternatively underwent autophagy and necrotic cell death. Whereas the proliferation defect appeared linked to a c-Rel-associated decrease in c-myc expression, identified pro-survival and pro-apoptotic targets were expressed at or near control levels consistent with the absence of apoptosis. Ultrastructural examination of Pt1 LCLs revealed a high level of cellular and ER stress that was further supported by gene expression profiling showing the upregulation of several genes involved in stress and inflammation. Apoptosis-independent cell death was accompanied by increased expression of the inflammatory marker, caspase-4. Using gene overexpression and siRNA knockdown we demonstrated that levels of c-Rel directly modulated expression of caspase-4 as well as other ER stress genes. Overall, these findings reveal the importance of c-Rel in maintaining LCL viability and that decreased expression results in ER stress and a default response leading to necrotic cell death.

Gut microbiota profiling in injection drug users with and without HIV-1 infection in Puerto Rico

Introduction

The full extent of interactions between human immunodeficiency virus (HIV) infection, injection drug use, and the human microbiome is unclear. In this study, we examined the microbiomes of HIV-positive and HIV-negative individuals, both drug-injecting and non-injecting, to identify bacterial community changes in response to HIV and drug use. We utilized a well-established cohort of people who inject drugs in Puerto Rico, a region with historically high levels of injection drug use and an HIV incidence rate disproportionately associated with drug use.

Methods

Using amplicon-based 16S rDNA sequencing, we identified amplicon sequence variants (ASVs) that demonstrated significant variations in the composition of microbial communities based on HIV status and drug use.

Results and discussion

Our findings indicate that the HIV-positive group exhibited a higher abundance of ASVs belonging to the genera Prevotella, Alloprevotella, Sutterella, Megasphaera, Fusobacterium, and Mitsuokella. However, Bifidobacteria and Lactobacillus ASVs were more abundant in injectors than in non-injectors. We examined the effect of drug use on the gut microbiome in both HIV-infected and non-infected patients, and found that multiple drug use significantly affected the microbial community composition. Analysis of differential of bacterial taxa revealed an enrichment of Bifidobacterium spp., Faecalibacterium spp., and Lactobacillus spp. in the multiple drug-injecting group. However, in the non-injecting group, Parabacteroides spp., Prevotella spp., Paraprevotella spp., Sutterella spp., and Lachnoclostridium spp. The presence of multiple drug-injecting groups was observed to be more prevalent. Our findings provide detailed insight into ASV-level changes in the microbiome in response to HIV and drug use, suggesting that the effect of HIV status and drug injection may have different effects on microbiome composition and in modulating gut bacterial populations.

Cognitive Intraindividual variability in injection drug use among Hispanic residents of Puerto Rico

Despite a high prevalence of injection drug use (IDU) in Puerto Rico, little is known about how it affects neuropsychological functioning in this population. Investigations of intra-individual variability (IIV) have alluded to its utility as a potential indicator of neural decline. The purpose of this study was to characterize IIV among Hispanic residents of Puerto Rico who engage in IDU. Injectors and non-injectors completed the Neuropsí Atención y Memoria battery. Measures of IIV were calculated for the overall test battery (OTB), the three battery indices, and three domains of attention, memory, and executive functioning. The injector group showed significantly greater IIV than the non-injector group on all measures (OTB, indices, and individual domains). Additionally, injectors showed significantly higher IIV in the domain of executive functioning compared to other cognitive domains and battery indices. In contrast, non-injectors did not show any significant within-group differences on any IIV measures. The higher performance variability observed in the IDU group suggests a negative influence of IDU on cognition, with executive functioning being more susceptible to these effects. These findings support the need for continued investigations into the clinical application of IIV for diagnostic and prognostic purposes in the Hispanic IDU population.

Immune profiling in Puerto Rican injection drug users with and without HIV-1 infection

Antiretroviral therapy has been effective in suppressing HIV viral load and enabling people living with HIV to experience longer, more conventional lives. However, as people living with HIV are living longer, they are developing aging-related diseases prematurely and are more susceptible to comorbidities that have been linked to chronic inflammation. Coincident with HIV infection and aging, drug abuse has also been independently associated with gut dysbiosis, microbial translocation, and inflammation. Here, we hypothesized that injection drug use would exacerbate HIV-induced immune activation and inflammation, thereby intensifying immune dysfunction. We recruited 50 individuals not using injection drugs (36/50 HIV+) and 47 people who inject drugs (PWID, 12/47 HIV+). All but 3 of the HIV+ subjects were on antiretroviral therapy. Plasma immune profiles were characterized by immunoproteomics, and cellular immunophenotypes were assessed using mass cytometry. The immune profiles of HIV+/PWID-, HIV-/PWID+, and HIV+/PWID+ were each significantly different from controls; however, few differences between these groups were detected, and only 3 inflammatory mediators and 2 immune cell populations demonstrated a combinatorial effect of injection drug use and HIV infection. In conclusion, a comprehensive analysis of inflammatory mediators and cell immunophenotypes revealed remarkably similar patterns of immune dysfunction in HIV-infected individuals and in people who inject drugs with and without HIV-1 infection.