Involvement of Epigenetic Promoter DNA Methylation of miR-124 in the Pathogenesis of HIV-1-Associated Neurocognitive Disorders

Intracellular HIV-1 Tat regulator induces epigenetic changes in the DNA methylation landscape

Introduction

The HIV regulatory protein Tat enhances viral transcription and also modifies host gene expression, affecting cell functions like cell cycle and apoptosis. Residual expression of Tat protein is detected in blood and other tissues even under antiretroviral treatment. Cohort studies have indicated that, despite virologic suppression, people with HIV (PWH) are at increased risk of comorbidities linked to chronic inflammation, accelerated immune ageing, and cellular senescence, sometimes associated with abnormal genomic methylation patterns. We analysed whether Tat influences DNA methylation and subsequently impacts the transcriptional signature, contributing to inflammation and accelerated ageing.

Methods

We transfected Jurkat cells with full-length Tat (Tat101), Tat's first exon (Tat72), or an empty vector (TetOFF). We assessed DNA methylation modifications via the Infinium MethylationEPIC array, and we evaluated transcriptomic alterations through RNA-Seq. Methylation levels in gene promoters or body regions were correlated to their expression data, and subsequently, we performed an overrepresentation analysis to identify the biological terms containing differentially methylated and expressed genes.

Results

Tat101 expression caused significant hyper- and hypomethylation changes at individual CpG sites, resulting in slightly global DNA hypermethylation. Methylation changes at gene promoters and bodies resulted in altered gene expression, specifically regulating gene transcription in 5.1% of differentially expressed genes (DEGs) in Tat101- expressing cells. In contrast, Tat72 had a minimal impact on this epigenetic process. The observed differentially methylated and expressed genes were involved in inflammatory responses, lipid antigen presentation, and apoptosis.

Discussion

Tat expression in HIV infection may constitute a key epigenetic modelling actor that contributes to HIV pathogenesis and chronic inflammation. Clinical interventions targeting Tat blockade may reduce chronic inflammation and cellular senescence related to HIV infection comorbidities.

Epigenetic modulation of myeloid cell functions in HIV and SARS-CoV-2 infection

Myeloid cells play a vital role in innate immune responses as they recognize and phagocytose pathogens like viruses, present antigens, produce cytokines, recruit other immune cells to combat infections, and contribute to the attenuation of immune responses to restore homeostasis. Signal integration by pathogen recognition receptors enables myeloid cells to adapt their functions by a network of transcription factors and chromatin remodelers. This review provides a brief overview of the subtypes of myeloid cells and the main epigenetic regulation mechanisms. Special focus is placed on the epigenomic alterations in viral nucleic acids of HIV and SARS-CoV-2 along with the epigenetic changes in the host's myeloid cell compartment. These changes are important as they lead to immune suppression and promote the progression of the disease. Finally, we highlight some promising examples of 'epidrugs' that modulate the epigenome of immune cells and could be used as therapeutics for viral infections.

Impact of Obefazimod on Viral Persistence, Inflammation, and Immune Activation in People With Human Immunodeficiency Virus on Suppressive Antiretroviral Therapy

BACKGROUND

Persistence of viral reservoirs has been observed in people with human immunodeficiency virus (HIV), despite long-term antiretroviral therapy (ART), and likely contributes to chronic immune activation and inflammation. Obefazimod is a novel drug that inhibits human immunodeficiency virus type 1 (HIV-1) replication and reduces inflammation. Here we assess whether obefazimod is safe and might impact HIV-1 persistence, chronic immune activation, and inflammation in ART-suppressed people with HIV.

METHODS

We evaluated obefazimod-related adverse events, changes in cell-associated HIV-1 DNA and RNA, residual viremia, immunophenotype, and inflammation biomarkers in blood and rectal tissue. We compared 24 ART-suppressed people with HIV who received daily doses of 50 mg obefazimod for 12 weeks (n = 13) or 150 mg for 4 weeks (n = 11) and 12 HIV-negative individuals who received 50 mg for 4 weeks.

RESULTS

The 50- and 150-mg doses of obefazimod were safe, although the 150-mg dose showed inferior tolerability. The 150-mg dose reduced HIV-1 DNA (P = .008, median fold change = 0.6) and residual viremia in all individuals with detectable viremia at baseline. Furthermore, obefazimod upregulated miR-124 in all participants and reduced the activation markers CD38, HLA-DR, and PD-1 and several inflammation biomarkers.

CONCLUSIONS

The effect of obefazimod by reducing chronic immune activation and inflammation suggests a potential role for the drug in virus remission strategies involving other compounds that can activate immune cells, such as latency-reversing agents.

Cell Differentiation Agent-2 (CDA-2) Inhibits the Growth and Migration of Saos-2 Cells via miR-124/MAPK1

BACKGROUND

CDA-2 (cell differentiation agent 2), isolated from healthy human urine, exerts antitumor effects in multiple types of cancer cells. However, its role in osteosarcoma has not been studied.

METHODS

The MTT assay was used to examine the cell proliferation rate. A colony formation assay was used to examine cell growth. The Transwell assay was used to examine cell migration ability. A real-time PCR assay was used to examine the expression levels of miR-124 and MAPK1. A Western blot assay was used to examine protein expression levels. MAPK1 was selected as a possible target of miR-124, and the targeting relationship was examined by a luciferase reporter assay.

RESULTS

We revealed that CDA-2 decreased the growth, migration and invasion ability of the osteosarcoma cell line Saos-2. Further study revealed that CDA-2 elevated the expression level of miR-124. MAPK1 was identified as a downstream target of miR-124. Knockdown of miR-124 or overexpression of MAPK1 counteracted CDA-2's effects on cell growth and invasion.

CONCLUSION

Our data revealed that the miR-124/MAPK1 axis mediated CDA-2's function in Saos-2 cells. CDA-2 can be used as a new treatment strategy for osteosarcoma.

A TGFBR2/SMAD2/DNMT1/miR-145 negative regulatory loop is responsible for LPS-induced sepsis

The critical roles of TGFBR2/Smad2 signaling have been established in LPS-induced sepsis, however, the underlying mechanisms by which TGFBR2/Smad2 signaling was regulated in LPS-induced sepsis are still confused. Here, miRNA-based on RNA-sequencing dataset revealed that miR-145 was significantly decreased in human umbilical vein endothelial cells (HUVECs) following LPS treatment. Bioinformatics, luciferase reporter and RNA immune co-precipitation (RIP) assays showed that miR-145 could directly target TGFBR2 and thus inactivated TGFBR2/Smad2 axis. On the contrary, luciferase reporter and chromatin immunoprecipitation (ChIP) analysis showed that Smad2 could directly bind to DNA methyltransferase 1 (DNMT1), the upregulation of which led to miR-145 promoter hypermethylation and downregulation of miR-145 expression, conversely promoting TGFBR2 expression. Notably, knockdown of TGFBR2 partially rescued the inhibition on miR-145 expression induced by LPS treatment. Additionally, we found that knockdown of TGFBR2 or overexpression of miR-145 attenuated LPS-induced sepsis and prolonged the overall survival of septic mice. Furthermore, TGFBR2 overexpression abrogated miR-145 overexpression-mediated attenuation on LPS-induced sepsis. Our results demonstrate the TGFBR2/SMAD2/DNMT1/miR-145 negative regulatory loop is responsible for LPS-induced sepsis.