Characteristics of alveolar macrophages in bronchioalveolar lavage fluids from active tuberculosis patients identified by single-cell RNA sequencing

Abstract

Tuberculosis (TB), is an infectious disease caused by Mycobacterium tuberculosis ( M. tuberculosis ), and presents with high morbidity and mortality. Alveolar macrophages play an important role in TB pathogenesis although there is heterogeneity and functional plasticity. This study aimed to show the characteristics of alveolar macrophages from bronchioalveolar lavage fluid (BALF) in active TB patients. Single-cell RNA sequencing (scRNA-seq) was performed on BALF cells from three patients with active TB and additional scRNA-seq data from three healthy adults were established as controls. Transcriptional profiles were analyzed and compared by differential geneexpression and functional enrichment analysis. We applied pseudo-temporal trajectory analysis to investigate correlations and heterogeneity within alveolar macrophage subclusters. Alveolar macrophages from active TB patients at the single-cell resolution are described. We found that TB patients have higher cellular percentages in five macrophage subclusters. Alveolar macrophage subclusters with increased percentages were involved in inflammatory signaling pathways as well as the basic macrophage functions. The TB-increased alveolar macrophage subclusters might be derived from M1-like polarization state, before switching to an M2-like polarization state with the development of M. tuberculosis infection. Cell-cell communications of alveolar macrophages also increased and enhanced in active TB patients. Overall, our study demonstrated the characteristics of alveolar macrophages from BALF in active TB patients by using scRNA-seq.

From immunology to artificial intelligence: revolutionizing latent tuberculosis infection diagnosis with machine learning

“…scRNA-seq is a powerful tool that allows for in-depth exploration of cellular heterogeneity and gene expression profiles at a single-cell resolution [ 250 – 253 ]. While scRNA-seq is primarily used to study gene expression patterns and cellular dynamics in various diseases, it also holds the potential to aid in the diagnosis and understanding of TB [ 254 , 255 ]. By utilizing scRNA-seq, researchers can assess the transcriptomic features of individual immune cells within LTBI patients, providing detailed information on cell composition, functional status, and immune responses related to LTBI [ 256 ].…”

Mechanisms of lung damage in tuberculosis: implications for chronic obstructive pulmonary disease

“…M2 also drives tissue repair and regeneration ( Kasmi and Stenmark, 2015 ; Marino et al., 2015 ; Arora et al., 2018 ; Shapouri-Moghaddam et al., 2018 ). Since macrophage polarization states affect the growth of M.tb bacilli in either a restrictive or permissive manner, a fine balance between M1 and M2 phenotypes ensures containment of the M.tb bacilli with minimal tissue damage ( Refai et al., 2018 ; Chen et al., 2022 ). In chronic inflammation, excessive M1 activity orchestrates tissue damage.…”

“…By the end of a month, both cellular phenotypes have increased in the lung environment, demonstrating both effector and memory phenotypes ( Feng et al., 1999 ). Half of these cells are CD69+ ( Kornfeld et al., 1999 ; Refai et al., 2018 ; Chen et al., 2022 ), indicating that activated T cells migrate to the site of infection, interact with M.tb -infected macrophages and DCs through CD40L on CD4+ T cells and CD40 on macrophages or dendritic cells ( Kalams and Walker, 1998 ; Clarke, 2000 ). The outcome was previously reported as enhanced antigen presentation and costimulatory activity resulting in the generation of robust CD4+ and CD8+T cells ( Kalams and Walker, 1998 ; Clarke, 2000 ).…”

Research progress of single-cell sequencing in tuberculosis

“…It focuses on the macrophage subgroups related to inflammatory function, and nine macrophage subgroups have been identified, four of which are in the M2 polarization state. At the same time, it was found that the interaction between macrophages and other cells was enhanced after infection (78). In a word, it is feasible to use scRNA-seq to determine the way of bacterial growth control in the macrophage subgroup.…”