From defense to demise: autophagy-induced neutrophil death after peptoanaerobacter stomatis challenge 3834

Description Neutrophil dysregulation plays a crucial role in the onset and progression of periodontitis (PD). High throughput culture-independent techniques applied to human dental plaque identified Peptoanaerobacter stomatis (Ps) as a notable putative pathogen in PD. However, this organism has recently been found in squamous cell carcinoma, suggesting broader pathogenic implications. Neutrophil interaction with Ps leads to hyperactivation of these cells. However, the underlying cellular mechanisms remain unexplored. Preliminary RNA-seq analysis of Ps-challenged neutrophils revealed autophagy among top upregulated pathways, with increased expression of autophagy-specific genes, such as LC3B, GABARAPL2, and ATG7. Additionally, neutrophil autophagic vacuolation and LC3B expression were induced by Ps challenge, as confirmed by transmission electron microscopy and western blot, respectively. Also, this bacteria-neutrophil interaction results in the activation of transcription factor (TF) EB, a key regulator of autophagy. Ps triggers high reactive oxygen species (ROS) production by neutrophils, and LC3B expression was reduced after ROS inhibition, indicating ROS-dependent autophagy. While autophagy promotes cell survival under stress, dysregulated autophagy can contribute to cell death. Ps challenge accelerated neutrophil apoptosis at the 3- and 6-hour time points and autophagy inhibition with 3-MA mitigated this effect, implicating this process in inflammation and immune cell turnover.