Venugopalan, R. | Search bioRxiv

bioRxiv2025

Spatially-distinct programming of macrophage diversity within the granulomas of Mycobacterium tuberculosis infected nonhuman primates

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is defined by granulomas-- immune aggregates that either contain or support bacterial replication. Macrophages, fundamental components of these lesions, are crucial to TB pathogenesis, yet their phenotypic and functional diversity is incompletely understood. Here, we used single-cell RNA sequencing and immunofluorescence to profile macrophages in lung tissue and granulomas from a nonhuman primate model of early TB. We identified distinct subsets, including embryonic-origin tissue-resident alveolar macrophages and monocyte-derived alveolar and interstitial macrophages, with distinct spatial localization in granulomas. Tissue-resident alveolar macrophages and a subset undergoing epithelial-to-mesenchymal transition accounted for the highest frequency of Mtb-infected cells. Infected cells exhibited differential expression of immune- and migration-associated genes compared to uninfected counterparts, suggesting Mtb either induces or exploits these pathways as a survival strategy. These findings highlight macrophage heterogeneity as a major driver of differential susceptibility to Mtb and provide insights relevant to future immunomodulatory strategies.

immunology↗

bioRxiv2025

The immunometabolic topography of tuberculosis granulomas governs cellular organization and bacterial control

Despite being heavily infiltrated by immune cells, tuberculosis (TB) granulomas often subvert the host response to Mycobacterium tuberculosis (Mtb) infection and support bacterial persistence. We previously discovered that human TB granulomas are enriched for immunosuppressive factors typically associated with tumor-immune evasion, raising the intriguing possibility that they promote tolerance to infection. In this study, our goal was to identify the prime drivers for establishing this tolerogenic niche and to determine if the magnitude of this response correlates with bacterial persistence. To do this, we conducted a multimodal spatial analysis of 52 granulomas from 16 non-human primates (NHP) who were infected with low dose Mtb for 9-12 weeks. Notably, each granulomas bacterial burden was individually quantified allowing us to directly ask how granuloma spatial structure and function relate to infection control. We found that a universal feature of TB granulomas was partitioning of the myeloid core into two distinct metabolic environments, one of which is hypoxic. This hypoxic environment associated with pathologic immune cell states, dysfunctional cellular organization of the granuloma, and a near-complete blockade of lymphocyte infiltration that would be required for a successful host response. The extent of these hypoxia-associated features correlated with worsened bacterial burden. We conclude that hypoxia governs immune cell state and organization within granulomas and is a potent driver of subverted immunity during TB.

immunology↗