Epigenetics Meets Immunology: Mechanisms, Crosstalk, and Therapeutic Implications

Background/Objectives: West Nile virus (WNV) remains a significant threat to human health, with no approved antiviral treatments or vaccine available. A better understanding of the molecular mechanisms governing flavivirus–host interactions is needed to identify host regulatory pathways involved in infection. This study aimed to investigate how WNV infection remodels the host miRNA–mRNA regulatory landscape. Methods: WNV-induced changes in host miRNA expression in HEK-293 cells were profiled using miRNA-Seq. Transcriptome-wide host gene expression changes in WNV-infected cells were analysed using RNA-Seq. Gene Ontology and pathway enrichment analyses were conducted using DAVID. Integrated miRNA–mRNA network reconstruction was performed using Cytoscape based on the experimentally validated miRNA–mRNA interactions in miRNet database. Results: WNV infection induced global changes in host miRNA expression, with pathogenic NY99 and non-pathogenic Kunjin strains of the virus producing overlapping and strain-specific alterations in the miRNA landscape. Transcriptome analysis showed strong induction of interferon-related responses and activation of NF-κB and MAPK signalling pathways in the infected cells. In contrast, pathways associated with RNA processing, splicing, and proteasomal degradation were downregulated. Integrated miRNA–mRNA network analysis identified miR-197-3p, miR-301b-3p, miR-129-3p, miR-3662, and miR-128-5p as candidate regulatory hubs involved in WNV-induced transcriptome remodelling. These networks suggested that miRNA-mediated regulation may influence antiviral signalling, apoptosis, and RNA metabolism during infection. Conclusions: These findings suggest that WNV infection broadly remodels host miRNA–mRNA regulatory networks and identifies candidate miRNAs that may contribute to the regulation of antiviral and cellular stress responses. These predicted regulatory interactions provide a foundation for future experimental validation. Full article

Background/Objectives: As important post-transcriptional and epigenetic regulators of gene expression, miRNAs play a pivotal role in modulating host–virus interactions. While prior reviews have addressed either direct miRNA–HIV genome interactions or miRNA-mediated immune modulation in isolation, the integrated dual functionality of these molecules has not been systematically characterized. This review aimed to comprehensively explore how miRNAs that target the HIV-1 genome simultaneously modulate key innate and adaptive host immune signaling pathways. The conceptual novelty of this study is determined not by the identification of previously unknown miRNA-target gene pairs, but by the systemic integration of two regulatory levels (direct inhibition of the viral genome and modulation of the host cell immune signaling pathways) within a unified analytical framework. Such an integrated approach reveals a proviral regulatory network that remains non-obvious when each of these levels is examined separately. Methods: A narrative review was conducted using PubMed, Scopus, Web of Science, and Google Scholar (all years through 2025). In Stage 1, publications reporting experimentally confirmed interactions between host miRNAs and the HIV-1 genome were identified, yielding a curated set of 15 miRNAs. In Stage 2, target genes for each miRNA were retrieved from miRTarBase, TarBase (experimentally validated) and TargetScan 8.0 (in silico predicted). In Stage 3, target genes were manually mapped to key immune signaling pathways (TLR, NF-κB, JAK-STAT). In Stage 4, targeted literature searches were performed for each miRNA–target gene pair to identify direct experimental evidence of interaction. All stages were performed by two independent researchers, with discrepancies resolved by a third. Results: Fifteen host miRNAs with experimentally confirmed binding to the HIV-1 genome were identified, targeting viral genes including nef, pol, vpr, gag, env, vif, and the 3′-UTR. Thirteen of these miRNAs were found to regulate components of major immune pathways. miR-92a-3p, miR-29a/b-3p, miR-150-5p, and miR-125b-5p emerged as the most pleiotropic regulators, simultaneously suppressing TLR signaling (TLR3, TLR7, TLR8, MyD88, TRAF3/6, IRAK1/4), NF-κB components (REL, RELA, NFKB1), JAK-STAT effectors (STAT1–3, STAT5A/B, JAK2), and negative regulators of cytokine signaling (SOCS and PIAS family proteins). miR-133b and miR-196b-5p were found to selectively regulate SOCS/PIAS proteins without involvement in other analyzed pathways, suggesting potential for selective therapeutic targeting. Conclusions: The analyzed miRNAs exhibit functional dualism, acting as direct post-transcriptional suppressors of the HIV-1 genome while simultaneously functioning as epigenetic modulators of host immune signaling. These two modes of action are not independent but together form a conceptual framework of a self-reinforcing proviral regulatory network that, based on the synthesis of published evidence, is proposed to promote viral latency and immune evasion. The identified miRNAs represent promising, albeit complex, targets for novel therapeutic strategies aimed at eliminating latent HIV reservoirs. Full article

Chromatin dynamics are usually modulated by histone epigenetic post-translational modifications, which rapidly and reversibly govern accessibility and transcriptional responsiveness. During microbial infection, this regulatory layer becomes a highly contested interface where host defense mechanisms and pathogen-driven subversion strategies converge and compete. Many infectious agents exploit chromatin to reprogram gene expression, creating cellular environments that are conducive to infection, proliferation, and persistence. Diverse strategies have been described for viruses, bacteria, fungi, protozoa and nematodes, including the direct secretion of acetyltransferases and methyltransferases, interference with host chromatin-binding proteins, subcellular localization of transcriptional factors or epigenetic regulators, and metabolic availability manipulation. Concurrently, host cells activate immune and stress-response genes to mount rapid, adaptable antimicrobial responses. Recent advances in genome-wide, single-cell, and spatial omics profiling have begun to reveal the temporal and cell-type-specific dynamics of the host genome at the core of infection. This review synthesizes current insights into how chromatin is rewired by the major categories of pathogens during infection, highlighting representative case studies across infective agents and the functional consequences for immunity and cell fate. In addition, we discuss emerging techniques for epigenomic and transcriptomic data collection, and the potential of targeted host-directed therapeutic strategies. Chromatin regulation is thus a promising field of study and a possible target for next-generation interventions. Full article

The innate immune system protects against infection and cellular damage by recognizing conserved pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Emerging evidence suggests that aberrant epigenetic modifications—such as altered DNA methylation and histone marks—can serve as immunogenic signals that activate pattern recognition receptor (PRR)-mediated immune surveillance. This review explores the concept that epigenetic marks may function as DAMPs or even mimic PAMPs. I highlight how unmethylated CpG motifs, which are typically suppressed using host methylation, are recognized as foreign via Toll-like receptor 9 (TLR9). I also examine how cytosolic DNA sensors, including cGAS, detect mislocalized or hypomethylated self-DNA resulting from genomic instability. In addition, I discuss how extracellular histones and nucleosomes released during cell death or stress can act as DAMPs that engage TLRs and activate inflammasomes. In the context of cancer, I review how epigenetic dysregulation can induce a “viral mimicry” state, where reactivation of endogenous retroelements produces double-stranded RNA sensed by RIG-I and MDA5, triggering type I interferon responses. Finally, I address open questions and future directions, including how immune recognition of epigenetic alterations might be leveraged for cancer immunotherapy or regulated to prevent autoimmunity. By integrating recent findings, this review underscores the emerging concept of the epigenome as a target of innate immune recognition, bridging the fields of immunology, epigenetics, and cancer biology. Full article