The Rectal Mucosal Myeloid Niche in HIV-1 Persistence: Reservoir Support, Viral Sequestration, and Therapeutic...

Persistent HIV-1 reservoirs remain a major barrier to a durable functional cure despite long-term suppressive antiretroviral therapy. Although resting memory CD4⁺ T cells constitute the best-characterized cellular reservoir, tissue microenvironments shape viral persistence and immune clearance. The rectal mucosa represents a specialized tissue niche containing HIV-susceptible target cells, antigen-presenting cells, microbial products, inflammatory cues, and local metabolic signals. Within this setting, myeloid-lineage cells, particularly tissue-resident macrophages and dendritic cells, may contribute to HIV-1 persistence through mechanisms distinct from classical T-cell latency. Here, we review how rectal mucosal macrophages may support HIV-1 persistence through longevity, resistance to apoptosis, metabolic adaptation, epigenetic regulation, and sequestration of virions within virus-containing compartments. We also discuss the dual role of mucosal dendritic cells as sentinels that capture and transfer HIV-1 to CD4⁺ T cells, while considering the limited evidence for inducible proviral persistence in selected anatomical and cellular contexts. Importantly, we further distinguish bona fide reservoir-bearing cells from reservoir-supportive mechanisms, including viral capture, trans-infection, immune suppression, and niche-mediated protection. We also highlight how mucosal dysbiosis, barrier disruption, microbial metabolites, chronic interferon signaling, and immunoregulatory myeloid programs may stabilize HIV-1 persistence in rectal tissues. Integrating intact proviral assays, functional measurements, single-cell profiling, multiplex imaging, and spatial transcriptomics will be critical for defining myeloid-associated persistence and guiding tissue-targeted HIV-1 cure strategies.