Gene exprssion at single cell level in patients broncoalveolar lavage (BAL) cells stimulated ex vivo with bacterial lysate OM-85

OM-85 is a bacterial lysate used in clinical practice to reduce duration and frequency of recurrent respiratory tract infections. Whereas knowledge on its regulatory effects in vivo has substantially advanced, the mechanisms of OM-85 sensing remain inadequately addressed.The purpose of this study was to investigate the transptomic profile of human airway immune cells in the BAL after ex vivo stimulation with OM-85 at the single cell level and determine to what extent OM-85-induced gene signature in different myeloid cell subsets is dependent on TLR2/TLR4 expression. To this aim we harvested Bronchoalveolar lavage fluid (BALF) cells from four subjects including two COPD (patients 1 and 3), one pulmonary silicosis (patient 4), and a patient with healthy lung (patient 2). BAL cells were stimulated or not with isotype control antibody (mIgG1k) or a combination of Anti-hTLR2 and Anti-hTLR4 (10ug/ml each) for 90 min, followed by stimulation with bacterial lysate OM-85 (150ug/ml) for 3hr. sc-RNA-seq was performed on these samples to assesss the gene expression profiles of various myeloid cell subsets.