Intranasal exposure to commensal bacterium Rothia mucilaginosa protects against influenza A virus infection.

The respiratory tract hosts a diverse microbial community whose composition varies with anatomical location and throughout life. Rothia mucilaginosa, a common commensal of the upper respiratory tract and oral cavity, has recently been recognized for its ability to inhibit bacteria-triggered pro-inflammatory responses. However, its role in modulating the immune response to viral infections such as influenza A virus (IAV) pneumonia, remains unknown.

Pharmacological inhibition of cathepsin S and of NSPs-AAP-1 (a novel, alternative protease driving the activation of neutrophil serine proteases).

An uncontrolled activity of neutrophil serine proteases (NSPs) contributes to inflammatory diseases. Cathepsin C (CatC) is known to activate NSPs during neutrophilic differentiation and represents a promising pharmacological target in NSP-mediated diseases. In humans, Papillon-Lefèvre syndrome (PLS) patients have mutations in theirCTSC gene, resulting in the complete absence of CatC activity.

Dual neutrophil subsets exacerbate or suppress inflammation in tuberculosis via IL-1β or PD-L1.

Neutrophils can be beneficial or deleterious during tuberculosis (TB). Based on the expression of MHC-II and programmed death ligand 1 (PD-L1), we distinguished two functionally and transcriptionally distinct neutrophil subsets in the lungs of mice infected with mycobacteria. Inflammatory [MHC-II, PD-L1] neutrophils produced inflammasome-dependent IL-1β in the lungs in response to virulent mycobacteria and "accelerated" deleterious inflammation, which was highly exacerbated in IFN-γR mice.