Mechanosensitive ion channel Piezo1 mediates mechanical ventilation-exacerbated ARDS-associated pulmonary fibrosis.

INTRODUCTION: Pulmonary fibrosis is a major cause of the poor prognosis of acute respiratory distress syndrome (ARDS). While mechanical ventilation (MV) is an indispensable life-saving intervention for ARDS, it may cause the remodeling process in lung epithelial cells to become disorganized and exacerbate ARDS-associated pulmonary fibrosis. Piezo1 is a mechanosensitive ion channel that is known to play a role in regulating diverse physiological processes, but whether Piezo1 is necessary for MV-exacerbated ARDS-associated pulmonary fibrosis remains unknown. OBJECTIVES: This study aimed to explore the role of Piezo1 in MV-exacerbated ARDS-associated pulmonary fibrosis. METHODS: Human lung epithelial cells were stimulated with hydrochloric acid (HCl) followed by mechanical stretch for 48 h. A two-hitmodel of MV afteracidaspiration-inducedlunginjuryin mice was used. Mice were sacrificed after 14 days of MV. Pharmacological inhibition and knockout of Piezo1 were used to delineate the role of Piezo1 in MV-exacerbated ARDS-associated pulmonary fibrosis. In some experiments, ATP or the ATP-hydrolyzing enzyme apyrase was administered. RESULTS: The stimulation of human lung epithelial cells to HCl resulted in phenotypes of epithelial-mesenchymal transition (EMT), which were enhanced by mechanical stretching. MV exacerbated pulmonary fibrosis in mice exposed to HCl. Pharmacologicalinhibitionorknockout of Piezo1 attenuated the MV-exacerbated EMT process and lung fibrosis in vivo and in vitro. Mechanistically, the observed effects were mediated by Piezo1-dependent Ca2+ influx and ATP release in lung epithelial cells. CONCLUSIONS: Our findings identify a key role for Piezo1 in MV-exacerbated ARDS-associated pulmonary fibrosis that is mediated by increased ATP release in lung epithelial cells. Inhibiting Piezo1 may constitute a novelstrategyfor the treatment of MV-exacerbated ARDS-associated pulmonary fibrosis.

Curcumin ameliorates monosodium urate-induced gouty arthritis through Nod-like receptor 3 inflammasome mediation via inhibiting nuclear factor-kappa B signaling.

BACKGROUND: Monosodium urate (MSU) crystals-induced inflammation is a key initiator in gouty arthritis. Curcumin is an active ingredient possessing anti-inflammatory efficacy. But the underlying mechanism is not fully understood and its effect on gouty arthritis remains elusive. METHODS: We evaluated the effects of curcumin on cell viability in primary rat abdominal macrophages with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT). Then supernatants of MSU crystals-stimulated cells were collected and subjected to enzyme-linked immunosorbent assay for checking the modulation of curcumin on interleukin (IL)-1ß and tumor necrosis factor (TNF)-α. Meanwhile, cells were analyzed by using Western blot analysis and quantitative polymerase chain reaction (QPCR) to investigate the effects of curcumin on Nod-like receptor 3 (NLRP3) inflammasome/nuclear factor-kappa B (NF-κB) signaling. We also investigated the in vivo efficacy of curcumin with MSU-induced gouty arthritis rat models. RESULTS: Curcumin could reduce MSU crystals-induced IL-1ß and TNF-α in vitro. Western blot analysis and QPCR results revealed that curcumin regulated the production of these cytokines by suppressing the expression of inflammasome key components, including NLRP3, caspase-1. Further studies showed that the suppressive efficacy of curcumin on inflammasome was mediated by inhibiting MSU-induced NF-κB signaling activation. Intraperitoneal administration of curcumin could ameliorate symptoms of MSU-induced gouty arthritis, including the joint circumference, infiltration of neutrophils in knee joints, and production of IL-1ß, TNF-α, and elastase. Western blot analysis revealed that the levels of NLRP3, procaspase-1, caspase-1, pro-IL-1ß, and IL-1ß were downregulated by curcumin in vivo. CONCLUSIONS: These results indicated that curcumin could effectively ameliorate MSU crystal-induced gouty arthritis through NLRP3 inflammasome mediation via inhibiting NF-κB signaling both in vitro and in vivo, suggesting a promising active ingredient for the prevention and treatment of gouty arthritis.