Mechanosensation of Cyclical Force by PIEZO1 is Essential for Innate Immunity

Although cells of the immune system experience force and pressure throughout their lifecycle, almost nothing is known about how these mechanical processes regulate the immune response. Immune cells in highly mechanical organs, such as the lung, are constantly exposed to tonic and dynamically changing mechanical cues. Here using reverse genetics, we show that myeloid cells respond to force and alterations in cyclical hydrostatic pressure (CHP) via the mechanosensory ion channel (MSIC) PIEZO1. Unbiased RNA-sequencing from macrophages subjected to CHP reveals a striking state of proinflammatory reprogramming. We report a novel mechanosensory-immune signaling circuit which PIEZO1 initiates in response to CHP, activating c-JUN, upregulating Endothelin-1 (EDN1), and stabilizing HIF1α to facilitate a prolonged program of proinflammatory mediators. Using mice conditionally deficient of PIEZO1 in myeloid cells, and cellular depletion assays, we show infiltrating monocytes respond to cyclical force to recruit neutrophils and clear pulmonary Pseudomonas aeruginosa infection. Furthermore, myeloid PIEZO1 also drove lung pathology in a mouse model of pulmonary fibrosis. Our results demonstrate a novel environmental sensory axis that myeloid cells recognize to mount an inflammatory response, and is the first report showing a physiological role for PIEZO1 and mechanosensation in immunity. To observe any biological response to mechanostimulation, BMDMs from Piezo1fl/fl and Piezo1fl/fl, LysM Cre+ (ΔLysM) mice were incubated in the pressure chamber for 6 hours under either static or cyclical hydrostatic pressure and subjected to RNA-seq analysis.