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

Resistive spontaneous breathing exacerbated lipopolysaccharide-induced lung injury in mice

Background

Spontaneous respiratory mechanical force interacted with the primary lung injury and aggravated the progression of ARDS clinically. But the exact role and involved mechanism of it in the pathogenesis of ARDS animal model remained obscure.

Aim

This study was to investigate the effect of spontaneous respiratory mechanical force on lung injury of ARDS in mice.

Methods

Female C57BL/6 mice were subjected to resistive spontaneous breathing (RSB) by tracheal banding after 4-6 h of intranasal inhalation of LPS. Pulmonary function was examined by Buxco system, partial pressures of oxygen and carbon dioxide (PO2 and PCO2) were measured by a blood gas analyzer, and lung pathological changes were analyzed with hematoxylin and eosin staining. The levels of inflammatory markers were quantified by ELISA, total protein assay, and FACS analysis. The expression levels of mechanosensitive ion channels were detected by qRT-PCR and immunohistochemistry.

Results

The airway resistance (Raw) was increased and the tidal volume (TV) was decreased remarkedly in RSB group. RSB treatment did not affect PO2, PCO2, pathology and inflammation levels of lung in mice. The Raw increased and ventilatory indicators decreased in RSB + ARDS compared to ARDS significantly. Besides, RSB treatment deteriorated the changes of PO2, PCO2 and level of lactic acid induced by LPS. Meanwhile, RSB significantly promoted LPS-induced pulmonary histopathological injury, and elevated the levels of IL-1β, IL-6, TNF-α and total proteins, increased neutrophils infiltration. The expression level of Piezo1 in RSB + ARDS group was remarkably reduced compared to ARDS group and consistent with the severity of pulmonary damage.

Conclusion

RSB exacerbated LPS-induced ARDS hypoxemia and hypercapnia, inflammation and damage. The mechanosensitive protein Piezo1 expression decreased and may play an important role in the process.

Understanding COVID-19-associated endothelial dysfunction: role of PIEZO1 as a potential therapeutic target

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Due to its high infectivity, the pandemic has rapidly spread and become a global health crisis. Emerging evidence indicates that endothelial dysfunction may play a central role in the multiorgan injuries associated with COVID-19. Therefore, there is an urgent need to discover and validate novel therapeutic strategies targeting endothelial cells. PIEZO1, a mechanosensitive (MS) ion channel highly expressed in the blood vessels of various tissues, has garnered increasing attention for its potential involvement in the regulation of inflammation, thrombosis, and endothelial integrity. This review aims to provide a novel perspective on the potential role of PIEZO1 as a promising target for mitigating COVID-19-associated endothelial dysfunction.

Blockage of mechanosensitive Piezo1 channel alleviates the severity of experimental malaria-associated acute lung injury

BACKGROUND

Malaria-associated acute lung injury (MA-ALI) is a well-recognized clinical complication of severe, complicated malaria that is partly driven by sequestrations of infected red blood cells (iRBCs) on lung postcapillary induced impaired blood flow. In earlier studies the mechanosensitive Piezo1 channel emerged as a regulator of mechanical stimuli, but the function and underlying mechanism of Piezo1 impacting MA-ALI severity via sensing the impaired pulmonary blood flow are still not fully elucidated. Thus, the present study aimed to explore the role of Piezo1 in the severity of murine MA-ALI.

METHODS

Here, we utilized a widely accepted murine model of MA-ALI using C57BL/6 mice with Plasmodium berghei ANKA infection and then added a Piezo1 inhibitor (GsMTx4) to the model. The iRBC-stimulated Raw264.7 macrophages in vitro were also targeted with GsMTx4 to further explore the potential mechanism.

RESULTS

Our data showed an elevation in the expression of Piezo1 and number of Piezo1+-CD68+ macrophages in lung tissues of the experimental MA-ALI mice. Compared to the infected control mice, the blockage of Piezo1 with GsMTx4 dramatically improved the survival rate but decreased body weight loss, peripheral blood parasitemia/lung parasite burden, experimental cerebral malaria incidence, total protein concentrations in bronchoalveolar lavage fluid, lung wet/dry weight ratio, vascular leakage, pathological damage, apoptosis and number of CD68+ and CD86+ macrophages in lung tissues. This was accompanied by a dramatic increase in the number of CD206+ macrophages (M2-like subtype), upregulation of anti-inflammatory cytokines (e.g. IL-4 and IL-10) and downregulation of pro-inflammatory cytokines (e.g. TNF-α and IL-1β). In addition, GsMTx4 treatment remarkably decreased pulmonary intracellular iron accumulation, protein level of 4-HNE (an activator of ferroptosis) and the number of CD68+-Piezo1+ and CD68+-4-HNE+ macrophages but significantly increased protein levels of GPX4 (an inhibitor of ferroptosis) in experimental MA-ALI mice. Similarly, in vitro study showed that the administration of GsMTx4 led to a remarkable elevation in the mRNA levels of CD206, IL-4, IL-10 and GPX-4 but to a substantial decline in CD86, TNF-α, IL-1β and 4-HNE in the iRBC-stimulated Raw264.7 cells.

CONCLUSIONS

Our findings indicated that blockage of Piezo1 with GsMTx4 alleviated the severity of experimental MA-ALI in mice partly by triggering pulmonary macrophage M2 polarization and subsequent anti-inflammatory responses but inhibited apoptosis and ferroptosis in lung tissue. Our data suggested that targeting Piezo1 in macrophages could be a promising therapeutic strategy for treating MA-ALI.

Mechanical stiffness promotes skin fibrosis via Piezo1-Wnt2/Wnt11-CCL24 positive feedback loop

Skin fibrosis is characterized by the excessive accumulation of extracellular matrix (ECM) caused by fibrotic disorders of the skin. In recent years, ECM stiffness has emerged as a prominent mechanical cue that precedes skin fibrosis and drives its progression by promoting fibroblasts activation. However, how stiffness influences fibroblasts activation for skin fibrosis progression remains unknown. Here, we report a positive feedback loop mediated by the mechanosensitive ion channel Piezo1 and aberrant tissue mechanics in driving skin fibrosis. Piezo1 is upregulated in fibrotic skin in both humans and mice. Piezo1 knockdown dermal fibroblasts lose their fibroproliferative phenotypes despite being grown on a stiffer substrate. We show that Piezo1 acts through the Wnt2/Wnt11 pathway to mechanically induce secretion of C-C motif chemokine ligand 24 (CCL24, also known as eotaxin-2), a potent cytokine associated with fibrotic disorders. Importantly, adeno-associated virus (AAV)-mediated Piezo1 knockdown ameliorated the progression of skin fibrosis and skin stiffness in mice. Overall, increased matrix stiffness promotes skin fibrosis through the inflammatory Piezo1-Wnt2/Wnt11-CCL24 pathway. In turn, a stiffer skin microenvironment increases Piezo1 expression to exacerbate skin fibrosis aggression. Therefore, targeting Piezo1 represents a strategy to break the positive feedback loop between fibroblasts mechanotransduction and aberrant tissue mechanics in skin fibrosis.

Mechanosensitive channels in lung disease

Mechanosensitive channels (MS channels) are membrane proteins capable of responding to mechanical stress over a wide dynamic range of external mechanical stimuli. In recent years, it has been found that MS channels play an important role as "sentinels" in the process of cell sensing and response to extracellular and intracellular force signals. There is growing appreciation for mechanical activation of ion channels and their subsequent initiation of downstream signaling pathways. Members of the transient receptor potential (TRP) superfamily and Piezo channels are broadly expressed in human tissues and contribute to multiple cellular functions. Both TRP and Piezo channels are thought to play key roles in physiological homeostasis and pathophysiology of disease states including in the lung. Here, we review the current state of knowledge on the expression, regulation, and function of TRP and Piezo channels in the context of the adult lung across the age spectrum, and in lung diseases such as asthma, COPD and pulmonary fibrosis where mechanical forces likely play varied roles in the structural and functional changes characteristic of these diseases. Understanding of TRP and Piezo in the lung can provide insights into new targets for treatment of pulmonary disease.

[The expression and significance of Piezo1 in chronic rhinosinusitis with nasal polyps]

Objective:To explore the expression and importance of Piezo1, E-cadherin, and Vimentin in nasal polyps patients. Methods:Thirty-five patients undergoing endoscopic sinus surgery under general anesthesia were streamed into 20 cases of nasal polyps（NP group） and 15 cases of simple septoplasty without any sinus disease（Control group）. Immunofluorescence staining and Western Blot were applied to detect the protein level of Piezo1, E-cadherin, and Vimentin in NP tissues and nasal polyp-derived primary human nasal epithelial cells（pHNECs）. Also, BEAS-2B cell lines were treated with human TGF-β1 protein to establish epithelial mesenchymal transition（EMT） model in vitro and quantitative real-time polymerase chain reaction were used to calculate Piezo1 and above biomarkers in the model. Results:Compared with control group, Piezo1 and Vimentin showed higher level while E-cadherin was lower in NP tissues and pHNECs.In EMT model in vitro, Piezo1 and Vimentin were demonstrated higher expression with decreased level of E-cadherin. Conclusion:The tendency of Piezo1 is consistent with the mesenchymal-related biomarker Vimentin, going against with epithelial-related biomarker E-cadherin, implying its involvement with EMT process in nasal polyps.

Mechanotransductive receptor Piezo1 as a promising target in the treatment of fibrosis diseases

Fibrosis could happen in every organ, leading to organic malfunction and even organ failure, which poses a serious threat to global health. Early treatment of fibrosis has been reported to be the turning point, therefore, exploring potential correlates in the pathogenesis of fibrosis and how to reverse fibrosis has become a pressing issue. As a mechanism-sensitive cationic calcium channel, Piezo1 turns on in response to changes in the lipid bilayer of the plasma membrane. Piezo1 exerts multiple biological roles, including inhibition of inflammation, cytoskeletal stabilization, epithelial-mesenchymal transition, stromal stiffness, and immune cell mechanotransduction, interestingly enough. These processes are closely associated with the development of fibrotic diseases. Recent studies have shown that deletion or knockdown of Piezo1 attenuates the onset of fibrosis. Therefore, in this paper we comprehensively describe the biology of this gene, focusing on its potential relevance in pulmonary fibrosis, renal fibrosis, pancreatic fibrosis, and cardiac fibrosis diseases, except for the role of drugs (agonists), increased intracellular calcium and mechanical stress using this gene in alleviating fibrosis.

Mechanosensitive Piezo1 channel in physiology and pathophysiology of the central nervous system

Since the discovery of the mechanosensitive Piezo1 channel in 2010, there has been a significant amount of research conducted to explore its regulatory role in the physiology and pathology of various organ systems. Recently, a growing body of compelling evidence has emerged linking the activity of the mechanosensitive Piezo1 channel to health and disease of the central nervous system. However, the exact mechanisms underlying these associations remain inadequately comprehended. This review systematically summarizes the current research on the mechanosensitive Piezo1 channel and its implications for central nervous system mechanobiology, retrospects the results demonstrating the regulatory role of the mechanosensitive Piezo1 channel on various cell types within the central nervous system, including neural stem cells, neurons, oligodendrocytes, microglia, astrocytes, and brain endothelial cells. Furthermore, the review discusses the current understanding of the involvement of the Piezo1 channel in central nervous system disorders, such as Alzheimer's disease, multiple sclerosis, glaucoma, stroke, and glioma.

Fibrotic extracellular vesicles contribute to mechanical ventilation-induced pulmonary fibrosis development by activating lung fibroblasts via JNK signalling pathway: an experimental study

Recent research has revealed that mechanical ventilation (MV) could initiate ventilator-induced lung injury along with the initiation of the process of pulmonary fibrosis (PF), leading to MV-induced PF (MVPF). However, the underlying mechanism remains unclear. This study aimed to explore the role of MV-induced extracellular vesicles (MV-EVs) and the c-Jun N-terminal kinase (JNK) signalling pathway in the pathogenesis of MVPF in vivo and in vitro. The process of MV is accompanied by the secretion of MV-EVs, which could induce lung fibroblast activation. Furthermore, single-cell RNA-sequencing analysis revealed that the JNK pathway in lung fibroblasts was activated after MV initiation. Inhibiting the JNK pathway could both restrain MV-EV-induced lung fibroblast activation in vitro or reduce the severity of MVPF in vivo. In conclusion, this study demonstrated that MV-EVs contribute to MVPF progression by activating lung fibroblasts via the JNK signalling pathway and that inhibiting the secretion of EV and the activation of the JNK signalling pathway is a promising strategy for treating MVPF.

Attenuation of Ventilation-Enhanced Epithelial–Mesenchymal Transition through the Phosphoinositide 3-Kinase-γ in a Murine Bleomycin-Induced Acute Lung Injury Model

Mechanical ventilation (MV) used in patients with acute lung injury (ALI) induces lung inflammation and causes fibroblast proliferation and excessive collagen deposition—a process termed epithelial–mesenchymal transition (EMT). Phosphoinositide 3-kinase-γ (PI3K-γ) is crucial in modulating EMT during the reparative phase of ALI; however, the mechanisms regulating the interactions among MV, EMT, and PI3K-γ remain unclear. We hypothesized that MV with or without bleomycin treatment would increase EMT through the PI3K-γ pathway. C57BL/6 mice, either wild-type or PI3K-γ-deficient, were exposed to 6 or 30 mL/kg MV for 5 h after receiving 5 mg/kg AS605240 intraperitoneally 5 days after bleomycin administration. We found that, after bleomycin exposure in wild-type mice, high-tidal-volume MV induced substantial increases in inflammatory cytokine production, oxidative loads, Masson’s trichrome staining level, positive staining of α-smooth muscle actin, PI3K-γ expression, and bronchial epithelial apoptosis (p < 0.05). Decreased respiratory function, antioxidants, and staining of the epithelial marker Zonula occludens-1 were also observed (p < 0.05). MV-augmented bleomycin-induced pulmonary fibrogenesis and epithelial apoptosis were attenuated in PI3K-γ-deficient mice, and we found pharmacological inhibition of PI3K-γ activity through AS605240 (p < 0.05). Our data suggest that MV augmented EMT after bleomycin-induced ALI, partially through the PI3K-γ pathway. Therapy targeting PI3K-γ may ameliorate MV-associated EMT.