According to the WHO, 38 million individuals were living with human immunodeficiency virus (HIV), 25.4 million of which were using antiretroviral therapy (ART) at the end of 2019. Despite ART-mediated suppression of viral replication, ART is not a cure and is associated with viral persistence, residual inflammation, and metabolic disturbances. Indeed, due to the presence of viral reservoirs, lifelong ART therapy is required to control viremia and prevent disease progression into acquired immune deficiency syndrome (AIDS). Successful ART treatment allows people living with HIV (PLHIV) to achieve a similar life expectancy to uninfected individuals. However, recent studies have illustrated the presence of increased comorbidities, such as accelerated, premature immune aging, in ART-controlled PLHIV compared to uninfected individuals. Studies suggest that both HIV-infection and ART-treatment lead to mitochondrial dysfunction, ultimately resulting in cellular exhaustion, senescence, and apoptosis. Since mitochondria are essential cellular organelles for energy homeostasis and cellular metabolism, their compromise leads to decreased oxidative phosphorylation (OXPHOS), ATP synthesis, gluconeogenesis, and beta-oxidation, abnormal cell homeostasis, increased oxidative stress, depolarization of the mitochondrial membrane potential, and upregulation of mitochondrial DNA mutations and cellular apoptosis. The progressive mitochondrial damage induced by HIV-infection and ART-treatment likely contributes to accelerated aging, senescence, and cellular dysfunction in PLHIV. This review discusses the connections between mitochondrial compromise and cellular dysfunction associated with HIV- and ART-induced toxicities, providing new insights into how HIV and current ART directly impact mitochondrial functions and contribute to cellular senescence and aging in PLHIV. Identifying this nexus and potential mechanisms may be beneficial in developing improved therapeutics for treating PLHIV.

RUNX1 overlapping RNA (RUNXOR) is a long non-coding RNA and plays a pivotal role in the differentiation of myeloid cells via targeting runt-related transcription factor 1 (RUNX1). We and others have previously reported that myeloid-derived suppressor cells (MDSCs) expand and inhibit host immune responses during chronic viral infections; however, the mechanisms responsible for MDSC differentiation and suppressive functions, in particular the role of RUNXOR–RUNX1, remain unclear. Here, we demonstrated that RUNXOR and RUNX1 expressions are significantly upregulated and associated with elevated levels of immunosuppressive molecules, such as arginase 1 (Arg1), inducible nitric oxide synthase (iNOS), signal transducer and activator of transcription 3 (STAT3), and reactive oxygen species (ROS) in MDSCs during chronic hepatitis C virus (HCV) infection. Mechanistically, we discovered that HCV-associated exosomes (HCV-Exo) can induce the expressions of RUNXOR and RUNX1, which in turn regulates miR-124 expression via STAT3 signaling, thereby promoting MDSC differentiation and suppressive functions. Importantly, overexpression of RUNXOR in healthy CD33⁺ myeloid cells promoted differentiation and suppressive functions of MDSCs. Conversely, silencing RUNXOR or RUNX1 expression in HCV-derived CD33⁺ myeloid cells significantly inhibited their differentiation and expressions of suppressive molecules and improved the function of co-cultured autologous CD4 T cells. Taken together, these results indicate that the RUNXOR–RUNX1–STAT3–miR124 axis enhances the differentiation and suppressive functions of MDSCs and could be a potential target for immunomodulation in conjunction with antiviral therapy during chronic HCV infection.

Eradication of latent human immunodeficiency virus (HIV) infection is a global health challenge. Reactivation of HIV latency and killing of virus-infected cells, the so-called “kick and kill” or “shock and kill” approaches, are a popular strategy for HIV cure. While antiretroviral therapy (ART) halts HIV replication by targeting multiple steps in the HIV life cycle, including viral entry, integration, replication, and production, it cannot get rid of the occult provirus incorporated into the host-cell genome. These latent proviruses are replication-competent and can rebound in cases of ART interruption or cessation. In general, a very small population of cells harbor provirus, serve as reservoirs in ART-controlled HIV subjects, and are capable of expressing little to no HIV RNA or proteins. Beyond the canonical resting memory CD4⁺ T cells, HIV reservoirs also exist within tissue macrophages, myeloid cells, brain microglial cells, gut epithelial cells, and hematopoietic stem cells (HSCs). Despite a lack of active viral production, latently HIV-infected subjects continue to exhibit aberrant cellular signaling and metabolic dysfunction, leading to minor to major cellular and systemic complications or comorbidities. These include genomic DNA damage; telomere attrition; mitochondrial dysfunction; premature aging; and lymphocytic, cardiac, renal, hepatic, or pulmonary dysfunctions. Therefore, the arcane machineries involved in HIV latency and its reversal warrant further studies to identify the cryptic mechanisms of HIV reservoir formation and clearance. In this review, we discuss several molecules and signaling pathways, some of which have dual roles in maintaining or reversing HIV latency and reservoirs, and describe some evolving strategies and possible approaches to eliminate viral reservoirs and, ultimately, cure/eradicate HIV infection.

The interplay between long noncoding RNAs (lncRNAs) and microRNAs (miRNAs) is crucial in the epigenetic regulation of mRNA and protein expression, impacting the development and progression of a plethora of human diseases, such as cancer, cardiovascular disease, inflammatory-associated diseases, and viral infection. Among the many lncRNAs, growth arrest-specific 5 (GAS5) has garnered substantial attention for its evident role in the regulation of significant biological processes such as proliferation, differentiation, senescence, and apoptosis. Through miRNA-mediated signaling pathways, GAS5 modulates disease progression in a cell-type-specific manner, typically by influencing proteins involved in inflammation and cell death. While GAS5 is recognized as a tumor suppressor in cancer, recent reports highlight its broader regulatory capacity in non-cancerous diseases. Its modulation of protein expression through the GAS5/miRNA network has been shown to both mitigate and exacerbate disease, depending on the specific context. Furthermore, the therapeutic potential of GAS5 manipulation, via knockdown or overexpression, offers promising avenues for targeted interventions across human diseases. This review explores the dualistic impacts of the GAS5/miRNA network in conditions such as cancer, cardiovascular disease, viral infections, and inflammatory disorders. Through the evaluation of current evidence, we aim to provide insight into GAS5’s biological functions and its implications for future research and therapeutic development.

Extracellular vesicles (EVs) are membrane-bound particles secreted by most cell types that play a pivotal role in intercellular communication via transporting protein, nucleic acid, lipid, and metabolite cargos. Among EVs, exosomes are a well-characterized subtype, typically ranging from 10–150 nm in diameter and originating from the endosomal pathway via the formation of multivesicular bodies that fuse with the plasma membrane. EVs/exosomes can be isolated from various biological fluids and cultured cells, with production and yield influenced by the cell type and culture conditions. Isolation methods, including ultracentrifugation or density-based ultracentrifugation, tangential flow filtration, size-exclusion chromatography, immunoaffinity and membrane-affinity capture, and recently developed commercial equipment, offer distinct advantages and limitations in terms of purity, scalability, and exosome integrity. Characterization techniques, such as nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), cryogenic electron microscopy (cryo-EM), atomic force microscopy (AFM), Western blotting, flow cytometry, and dynamic light scattering (DLS), assess exosome size, morphology, and biomarker expression. Given their biocompatibility and inherent targeting capabilities across a diverse range of diseases, EVs/exosomes hold clinical promise as diagnostic biomarkers, cell-free therapeutics, drug delivery vehicles, immune modulators, and in regenerative medicine. However, these emerging fields in exosome medicine continue to face challenges in standardizing EV sourcing, production, purification, yield, bio-targeting, drug loading, and drug delivery. While EVs/exosomes represent a rapidly advancing frontier in biomedical science, robust protocols for standardization and scalable production will be essential for their successful translation into clinical applications. This article provides a comprehensive overview of EV/exosome origins, their biological functions, the approaches for their isolation and characterization, and their therapeutic potential.

We have previously demonstrated mitochondrial dysfunction in aging CD4 T cells from antiretroviral therapy (ART)-controlled people living with HIV (PLWH). However, the underlying mechanisms by which CD4 T cells develop mitochondrial dysfunction in PLWH remain unclear. In this study, we sought to elucidate the mechanism(s) of CD4 T cell mitochondrial compromise in ART-controlled PLWH. We first assessed the levels of reactive oxygen species (ROS), and we observed significantly increased cellular and mitochondrial ROS levels in CD4 T cells from PLWH compared to healthy subjects (HS). Furthermore, we observed a significant reduction in the levels of proteins responsible for antioxidant defense (superoxide dismutase 1, SOD1) and ROS-mediated DNA damage repair (apurinic/apyrimidinic endonuclease 1, APE1) in CD4 T cells from PLWH. Importantly, CRISPR/Cas9-mediated knockdown of SOD1 or APE1 in CD4 T cells from HS confirmed their roles in maintaining normal mitochondrial respiration via a p53-mediated pathway. Reconstitution of SOD1 or APE1 in CD4 T cells from PLWH successfully rescued mitochondrial function as evidenced by Seahorse analysis. These results indicate that ROS induces mitochondrial dysfunction, leading to premature T cell aging via dysregulation of SOD1 and APE1 during latent HIV infection.