Background: Which cell populations that determine the fate of bacteria in infectious granulomas remain unclear. Leprosy, a granulomatous disease with a strong genetic predisposition, caused by Mycobacterium leprae infection, exhibits distinct sub-types with varying bacterial load and is considered an outstanding disease model for studying host–pathogen interactions.
Methods: We performed single-cell RNA and immune repertoire sequencing on 11 healthy controls and 20 patients with leprosy, and integrated single-cell data with genome-wide genetic data on leprosy. Multiplex immunohistochemistry, and in vitro and in vivo infection experiments were conducted to confirm the multimodal omics findings.
Findings: Lepromatous leprosy (L-LEP) granulomas with high bacterial burden were characterised by exhausted CD8+ T cells, and high RGS1 expression in CD8+ T cells was associated with L-LEP. By contrast, tuberculoid leprosy (T-LEP) granulomas with low bacterial burden displayed enrichment in resident memory IFNG+ CD8+ T cells (CD8+ Trm) with high GNLY expression. This enrichment was potentially attributable to the communication between IL1B macrophages and CD8+ Trm via CXCL10-CXCR3 signalling. Additionally, IL1B macrophages in L-LEP exhibited antiinflammatory phenotype, with high APOE expression contributing to high bacterial burden. Conversely, IL1B macrophages in T-LEP were distinguished by interferon-γ induced GBP family genes.
Interpretation: The state of IL1B macrophages and functional CD8+ T cells, as well as the relationship between them, is crucial for controlling bacterial persistence within granulomas. These insights may indicate potential targets for host-directed immunotherapy in granulomatous diseases caused by mycobacteria and other intracellular bacteria.
BT - eBioMedicine DO - 10.1016/j.ebiom.2024.105342 LA - ENG M3 - Article N2 -Background: Which cell populations that determine the fate of bacteria in infectious granulomas remain unclear. Leprosy, a granulomatous disease with a strong genetic predisposition, caused by Mycobacterium leprae infection, exhibits distinct sub-types with varying bacterial load and is considered an outstanding disease model for studying host–pathogen interactions.
Methods: We performed single-cell RNA and immune repertoire sequencing on 11 healthy controls and 20 patients with leprosy, and integrated single-cell data with genome-wide genetic data on leprosy. Multiplex immunohistochemistry, and in vitro and in vivo infection experiments were conducted to confirm the multimodal omics findings.
Findings: Lepromatous leprosy (L-LEP) granulomas with high bacterial burden were characterised by exhausted CD8+ T cells, and high RGS1 expression in CD8+ T cells was associated with L-LEP. By contrast, tuberculoid leprosy (T-LEP) granulomas with low bacterial burden displayed enrichment in resident memory IFNG+ CD8+ T cells (CD8+ Trm) with high GNLY expression. This enrichment was potentially attributable to the communication between IL1B macrophages and CD8+ Trm via CXCL10-CXCR3 signalling. Additionally, IL1B macrophages in L-LEP exhibited antiinflammatory phenotype, with high APOE expression contributing to high bacterial burden. Conversely, IL1B macrophages in T-LEP were distinguished by interferon-γ induced GBP family genes.
Interpretation: The state of IL1B macrophages and functional CD8+ T cells, as well as the relationship between them, is crucial for controlling bacterial persistence within granulomas. These insights may indicate potential targets for host-directed immunotherapy in granulomatous diseases caused by mycobacteria and other intracellular bacteria.
PB - Elsevier BV PY - 2024 SP - 1 EP - 19 T2 - eBioMedicine TI - Cellular and molecular determinants of bacterial burden in leprosy granulomas revealed by single-cell multimodal omics UR - https://www.thelancet.com/action/showPdf?pii=S2352-3964%2824%2900378-5 VL - 108 SN - 2352-3964 ER -