Background: Patients colonized by Mycobacterium abscessus, such as people with cystic fibrosis (pwCF), are at risk of NTM Pulmonary Disease (NTM-PD) and display heterogeneous clinical outcomes. New reliable biomarkers, such as immune signatures, are among the unmet needs for better clinical management of NTM-PD.

Methods: We collected blood samples from adult pwCF stratified as follows: pwCF with no history of NTM detection and clinically stable (CF); pwCF with NTM-positive isolates and clinically stable (CF-NTM); pwCF with NTM-positive isolates and a clinical diagnosis for the risk of pulmonary disease (CF-NTM-PD). We isolated peripheral blood mononuclear cell (PBMCs) and plasma to perform single cell (sc)RNA-seq and Luminex assay.

Results: We performed scRNAseq on 12 PBMCs samples, identifying over 60000 cells and 10 cellular immune populations according to the expression levels of canonical markers. We performed differentially expressed genes (DEGs) analysis among the three groups in each cell population to identify transcriptomic signatures characterizing the CF-NTM-PD. When compared DEGs in samples from patients at risk of pulmonary disease (CF-NTM-PD) vs others (CF and CF-NTM), we identified unique RNA transcriptomic profiles activated in Monocyte, that were specifically upregulated in CD14+ Monocyte of CF-NTM-PD as hyperinflammatory monocyte responses. Moreover, we confirmed these differences evaluating CXCL10 levels in plasma among 23 proinflammatory cytokines.

Conclusions: Our scRNAseq data suggests that hyperinflammatory monocyte responses are present in pwCF with risk of NTM-PD