Human PD-1 agonist treatment alleviates neutrophilic asthma by reprogramming T cells.

BACKGROUND: Neutrophilic asthma is associated with disease severity and corticosteroid insensitivity. Novel therapies are required to manage this life-threatening asthma phenotype. Programmed cell death protein-1 (PD-1) is a key homeostatic modulator of the immune response for T-cell effector functions. OBJECTIVE: We sought to investigate the role of PD-1 in the regulation of acute neutrophilic inflammation in a murine model of airway hyperreactivity (AHR). METHODS: House dust mite was used to induce and compare neutrophilic AHR in wild-type and PD-1 knockout mice. Then, the therapeutic potential of a human PD-1 agonist was tested in a humanized mouse model in which the PD-1 extracellular domain is entirely humanized. Single-cell RNA sequencing and flow cytometry were mainly used to investigate molecular and cellular mechanisms. RESULTS: PD-1 was highly induced on pulmonary T cells in our inflammatory model. PD-1 deficiency was associated with an increased neutrophilic AHR and high recruitment of inflammatory cells to the lungs. Consistently, PD-1 agonist treatment dampened AHR, decreased neutrophil recruitment, and modulated cytokine production in a humanized PD-1 mouse model. Mechanistically, we demonstrated at the transcriptional and protein levels that the inhibitory effect of PD-1 agonist is associated with the reprogramming of pulmonary effector T cells that showed decreased number and activation. CONCLUSIONS: PD-1 agonist treatment is efficient in dampening neutrophilic AHR and lung inflammation in a preclinical humanized mouse model.

Molecular mechanisms of Guadecitabine induced FGFR4 down regulation in alveolar rhabdomyosarcomas.

Fibroblast growth factor receptor 4 (FGFR4) aberrant expression and activity have been linked to the pathogenesis of a variety of cancers including rhabdomyosarcomas (RMS). We found that treatment of alveolar rhabdomyosarcoma (aRMS) cells with Guadecitabine (SGI-110), a next-generation DNA methyltransferase inhibitor (DNMTi), resulted in a significant reduction of FGFR4 protein levels, 5 days post treatment. Chromatin immunoprecipitation-sequencing (ChIP-seq) in aRMS cells revealed attenuation of the H3K4 mono-methylation across the FGFR4 super enhancer without changes in tri-methylation of either H3K4 or H3K27. These changes were associated with a significant reduction in FGFR4 transcript levels in treated cells. These decreases in H3K4me1 in the FGFR4 super enhancer were also associated with a 240-fold increase in KDM5B (JARID1B) mRNA levels. Immunoblot and immunofluorescent studies also revealed a significant increase in the KDM5B protein levels after treatment in these cells. KDM5B is the only member of KDM5 (JARID1) family of histone lysine demethylases that catalyzes demethylation of H3K4me1. These data together suggest a pleiotropic effect of DNMTi therapy in aRMS cells, converging to significantly lower FGFR4 protein levels in these cells.