Mechanosensation of Cyclical Force by PIEZO1 is Essential for Innate Immunity
Ontology highlight
ABSTRACT: 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.
Project description:Macrophages play a pivotal role in mechanical force-induced inflammatory bone remodeling. Yet, how macrophages perceive mechanical stimuli and thereby modulate biological behaviors remain elusive. The orthodontic tooth movement (OTM) model was established to access the role of Piezo1 in modulating macrophage response upon mechanical stimuli. The potential functions and molecule mechanisms of Piezo1 were explored by bone marrow-derived macrophages (BMDMs) using mechanical stretch system, western blotting, immunofluorescence, flow cytometry and RNA sequencing. We first found macrophage proliferative phenotype enhanced at the later stage of force application. The biological variation mediated by mechanical force could be suppressed by Piezo1 inhibition. Furthermore, Piezo1 activated PI3K-AKT signaling was closely associated with macrophage proliferation upon mechanical stimuli. Additionally, Ccnd1 was authenticated as a critical downstream factor of PI3K-AKT signaling and conditional ablation of Ccnd1 in macrophages inhibited macrophage proliferation in mechanical force-induced bone remodeling procedure.
Project description:Piezo1 is a mechanosensitive ion channel that has gained recognition for its role in regulating diverse physiological processes. However, the influence of Piezo1 in inflammatory disease, including infection and tumor-immunity, is not well-studied. We postulated that Piezo1 links physical forces to immune regulation in myeloid cells. We discovered signal transduction via Piezo1 in myeloid cells and established this channel as the primary sensor of mechanical stress in these cells. Global inhibition of Piezo1 was protective against both cancer and septic shock and resulted in a diminution in suppressive myeloid cells. Moreover, deletion of Piezo1 in myeloid cells protected against cancer and increased survival in poly-microbial sepsis. Mechanistically, we show that mechanical stimulation promotes Piezo1-dependent myeloid cell expansion by suppressing Rb. We further show Piezo1-mediated silencing of Rb is regulated via upregulation of HDAC2. Collectively, our work uncovers Piezo1 as a targetable immune checkpoint that drives immune-suppressive myelopoiesis in cancer and infectious disease.
Project description:Mechanosensitive ion channels sense force and pressure in immune cells to drive the inflammatory response in highly mechanical organs. Here we report that Piezo1 channels repress group 2 innate lymphoid cells (ILC2s)-driven type 2 inflammation in the lungs. Piezo1 is induced on lung ILC2s upon activation, as genetic ablation of Piezo1 in ILC2s increases their function and exacerbates the development of airway hyperreactivity (AHR). Conversely, Piezo1 agonist Yoda1 reduces ILC2-driven lung inflammation. Mechanistically, Yoda1 inhibits ILC2 cytokine secretion and proliferation in a KLF2-dependent manner, as we further found that Piezo1 engagement reduces ILC2 oxidative metabolism. Consequently, in vivo Yoda1 treatment notably reduces the development of AHR in experimental models of ILC2-driven allergic asthma. Human circulating ILC2s express and induce Piezo1 upon activation, as Yoda1 treatment of humanized mice reduces human ILC2-driven AHR. Our studies define Piezo1 as a critical regulator of ILC2s and we propose the potential of Piezo1 activation as a novel therapeutic approach for the treatment of ILC2-driven allergic asthma.
Project description:Mechanosensitive ion channels sense force and pressure in immune cells to drive the inflammatory response in highly mechanical organs. Here we report that Piezo1 channels repress group 2 innate lymphoid cells (ILC2s)-driven type 2 inflammation in the lungs. Piezo1 is induced on lung ILC2s upon activation, as genetic ablation of Piezo1 in ILC2s increases their function and exacerbates the development of airway hyperreactivity (AHR). Conversely, Piezo1 agonist Yoda1 reduces ILC2-driven lung inflammation. Mechanistically, Yoda1 inhibits ILC2 cytokine secretion and proliferation in a KLF2-dependent manner, as we further found that Piezo1 engagement reduces ILC2 oxidative metabolism. Consequently, in vivo Yoda1 treatment notably reduces the development of AHR in experimental models of ILC2-driven allergic asthma. Human circulating ILC2s express and induce Piezo1 upon activation, as Yoda1 treatment of humanized mice reduces human ILC2-driven AHR. Our studies define Piezo1 as a critical regulator of ILC2s and we propose the potential of Piezo1 activation as a novel therapeutic approach for the treatment of ILC2-driven allergic asthma.
Project description:In China, the incidence of fracture non-unions is relatively high. Impaired endochondral ossification may lead to nonunion due to improper mechanical loading. As a mechanosensitive ion channel protein, Piezo1mediates mechanical transduction and induces calcium inward flow. Our early study showed that the osteogenic and angiogenic capacity of chondrocytes was reduced, if Piezo1 gene was knocked out on chondrocytes. Moreover, the expression of mitochondrion translation related gene LARS2 was signaling increased. Therefore, we hypothesize that the mechanical loading may cause endochondral ossification through the Piezo1- LARS2 signaling pathway. We will use conditioned gene knockout mice and Peizo1 knockdown stable cell line to support the hypothesis. Our goals include investigating the changes of Piezo1 expression during endochondral ossification of femoral fracture healing in mice under mechanical loading; investigating the response of Piezo1 channels on chondrocytes to mechanical stimulation and its role and mechanism in regulating chondrocyte osteogenesis and angiogenesis, maintaining the normal mitochondrial function in vitro; analysing the key molecular and signal network downstream of Piezo1 through the multi-omics techniques; and exploring the response mechanism of Piezo1 under vibrating stimulus. This project aims to study the molecular mechanism of Piezo1-mediated force-biological information transition and its role in endochondral ossification. We hope it provides an effective intervention target for preventing and treating fracture nonunion.
Project description:The mechanisms by which physical forces regulate cells to determine complexities of vascular structure and function are enigmatic. Here we show the role the ion channel subunit Piezo1 (FAM38A). Disruption of mouse Piezo1 gene disturbed vascular development and was embryonic lethal within days of the heart beating to cause blood flow. Importance of Piezo channels as sensors of blood flow was indicated by Piezo1 dependence of shear stress-evoked ionic current and calcium influx in endothelial cells and the ability of exogenous Piezo1 to confer shear stress sensitivity on cells that otherwise lacked. Downstream of this calcium influx was proteoase activity and spatial organization of endothelial cells to the polarity of the applied force. Without Piezo1, normal endothelial cell organization was lacking. The data suggest Piezo1 channels as pivotal integrators of vascular architacture with physiological mechanical force.
Project description:Mechanical force is a fundamental regulator of bone development and homeostasis. Mechanosensitive osteocytes are the most abundant bone cells that form interconnected dendrites to respond to mechanical stimuli and interact with the bone-forming osteoblasts and the bone-remodeling osteoclasts. However, the molecular mechanisms underlying osteocyte maturation and dendrite formation remain unclear. By generating a Piezo1 "knock-out" osteocyte cell line, we identified a key role of Piezo1-mediated mechanotransduction in osteocyte differentiation. QRT-PCR analysis revealed delayed osteocyte differentiation in the Piezo1 KO cells relative to WT cells. By performing bulk RNA sequencing of WT and Piezo1 KO OCY454 cells at early (D1), intermediate (D14), and late (D28) stages of differentiation allowed for the identification of key signaling pathways in driving normal osteocyte dfiferentiation, as well as those regulated by Piezo1 mechanotransduction.
Project description:Mechanical overload of the vascular wall is a pathological hallmark of life-threatening abdominal aortic aneurysms (AAA). However, how this mechanical stress resonates at the unicellular level of vascular smooth muscle cells (VSMC) is undefined. Here, we combined novel tweezers-based micromechanical system and single-cell RNA sequencing to map defective mechano-phenotype signatures of VSMC in AAA. Notably, theoretical modelling predicted that cytoskeleton alterations fueled cell membrane tension of VSMC, thereby modulating their mechanoallostatic responses which were validated by live micromechanical measurements. Mechanistically, VSMC gradually adopted a mechanically solid-like state by upregulating CSK crosslinker, α-actinin2, in the presence of AAA-promoting signal, Netrin-1, thereby directly powering the activity of mechanosensory ion channel Piezo1. Inhibition of Piezo1 prevented mice from developing AAA by alleviating pathological vascular remodeling. Our findings demonstrate that deviations of mechanosensation behaviors of VSMC is detrimental for AAA and identifies Piezo1 as a novel culprit of mechanically fatigued aorta in AAA.
Project description:Angiopoietin-Tie1 signaling is required for lymphatic vascular integrity and both ANGPT2 and TIE1 genetic variants have been associated with lymphedema in patients1, 2. Concurrent with growth-factor signaling, mechanical forces sensed by lymphatic endothelial cells (LECs) are also needed to regulate lymphatics3, 4. How these two pathways might interact in the lymphatic system is unknown. Here, we identified a regulatory network in LECs linking activation of the mechanosensory channel, PIEZO1 to Angiopoietin-Tie signaling and repression of a downstream FOXO1 transcriptional response. RNAseq analysis of dermal LECs from Tie1-deficient embryos showed persistent FOXO1 activity with downregulation of LEC-associated genes including Ccl21a, Foxc2, Gata2 and Gja4, as well as increased expression of the mechanosensory channel, Piezo1. Activation of PIEZO1 in human dermal LECs (HDLECs) by the small molecule agonist, Yoda1, triggered exocytosis of the Tie ligand, Angiopoietin-2 (ANGPT2), activation of Tie/AKT/PI3K signaling and export of FOXO1 out of the nucleus. Our data identify a novel molecular pathway linking mechano-transduction to ANGPT2-Tie1 activity and dynamic modulation of FOXO1 activity needed for patterning and function of the lymphatic system