Mberkadji Ngana Poster 2023

Mr Mberkadji Salem Ngana

Medical Research Council The Gambia at London School of Hygiene and Tropical Medecine, The Gambia

‘Analysis of the impact of monocytes differentiation on Mycobacterium tuberculosis complex infection’

Poster Abstract

Background: Macrophages are significant phagocytes of the Mycobacterium tuberculosis complex (MTBC), which also use them as their host. The macrophage’s phenotypes determine the faith of phagocytosed MTBC. We study the influence of macrophage phenotype on MTBC lineages infection outcomes by fusing human monocyte-derived macrophages polarised into classical M1 or alternative M2.

Methods: Monocytes were isolated from venous blood of healthy donors and polarised in-vitro in GM-CSF or M-CSF for 6 days, followed by IFN-, IL-4, or IL-13 for 2 days or culture with medium alone to generate M1, IL4-M2, IL-13-M2, and M0 macrophages, respectively. The polarised macrophages were infected with reporter-gene-tagged clinical isolates of M. tuberculosis lineage2 (Beijing), lineage4 (Euro-America), and M. africanum lineage6 (West Africa) at     MOI 1:1. The intracellular bacteria growth and the expression of functional surface markers were evaluated by measuring bacteria fluorescence and flow cytometry analysis.

Results: Uninfected M1 macrophage expressed higher levels of CD163+, CD206+, CD11b+, CD86+ while M2 macrophage higher HLA-DR+, CD16+, CD36+, MERKT+.  Most of the investigated markers were higher or lower after bacterial infection, generating a mixed M1/M2 phenotype depending on the MTBC lineages. Following Mtb-lineage4 infection, CD86+cells were significantly lower in M1 than M2 macrophages (P=0.034). Compared to uninfected macrophages, intracellular bacteria were significantly high in M0 and M2 following Mtb-lineage4 infection (P=0.009; 0.046 and 0.019), and M1, M2 and M0 in response to Maf-lineage6 infection (P=0.028; 0.034 and 0.0079).

Conclusion: The macrophage polarisation affects their responses to MTBC lineages infection; M1 macrophages control Mtb-lineages infection better than Maf-lineages. In contrast, M2 macrophages were permissive to all the MTBC lineages tested.  The ongoing study will assess the cytokines response to understand the factors of these response differences. 

Biography

I am from the Chad Republic and have a master's degree graduate in Immunology and infection from Cheikh Anta Diop University, Senegal. Currently, I am a scientific officer in the TB Immunology Laboratory at the MRC Unit Gambia at LSHTM. Our research team investigate the impact of monocyte differentiation on MTBC infection. My role spans immunological assays using whole blood from study participants for PBMCs isolation, monocytes extraction and differentiation, and in vitro cells infection assay to study host-pathogen interaction using flow cytometry and ELISA. My vision is to contribute to developing a novel treatment strategy against tuberculosis in Africa.