American Journal of Respiratory Cell and Molecular Biology最新文献

IL-33 released by injurious stimuli to airway epithelium activates innate lymphoid cells (ILCs) that express IL-13. IL-33 and ILCs have an important role in type 2 (T2)-high asthma, but their influence on airway dysfunction induced by irritants is unclear. We examined the effects of Cl₂ inhalation on IL-33 release, pulmonary ILCs, airway inflammation, and airway hyperresponsiveness (AHR). Cl₂ exposure resulted in IL-33 release and increased ILC2s in the airways of BALB/c mice. Inhibition of the IL-33 receptor did not alter AHR, but depletion of ILCs augmented AHR. Recombinant IL-33 given for 3 successive days to wild-type and Rag1^-/- (recombinant activating gene-deficient) mice, deficient in mature T and B cells, further increased ILC2s and inhibited Cl₂-induced neutrophilia and AHR, whereas Rag^-/- IL2rγ^-/- mice, lacking ILCs, did not show these effects. IL-33 increased IL-13 expression by ILC2s, and IL-13 neutralization exacerbated AHR, whereas IL-13 administration reduced AHR in Cl₂-exposed Rag1^-/- mice. IL-33 biased alveolar macrophages toward the M2 phenotype, partly mediated by IL-13. Depletion with clodronate liposomes abrogated the IL-33 protective effect on AHR. The data suggest that the expansion of ILC2s by IL-33 activates a protective pathway involving IL-13 and macrophages against airway dysfunction and inflammation after inhalation of Cl₂.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, interstitial lung disease lacking an efficient drug to reverse it. Thus, there is an urgent need to elucidate the complex pathogenesis of IPF and identify new therapeutic targets. It has been revealed that the pathophysiology of IPF is a highly orchestrated process that includes multiple cell types in which the contribution of endothelial cells (ECs) has attracted researchers' attention. However, although the involvement of ECs in fibrosis has been recognized, the underlying key molecules driving these changes are not well defined. In this study, we revealed that von Willebrand factor (VWF), a marker of damaged ECs, and endothelial dysfunction are positively correlated with IPF progression on the basis of reanalysis of gene expression profiles of patients with IPF. Next, we discovered that VWF deficiency attenuated fibrosis in experimental models, including human cell lines (in vitro) and mice (in vivo). Mechanistically, VWF deficiency inhibited endothelial-to-mesenchymal transition, regulated vascular abnormalities, and limited M2 macrophage infiltration, which were achieved, at least in part, by the inhibition of Wnt signaling. Our findings provided evidence for the pivotal role of ECs in IPF and revealed that VWF might be a driving factor of endothelial-to-mesenchymal transition, suggesting that VWF can be developed as a potential therapeutic target against IPF.

Surfactant protein (SP)-A, an octadecamer composed of SP-A1 and SP-A2, is secreted into the alveolar space. Heterozygous variations in SFTPA1 and SFTPA2, reported to impair protein secretion, have been associated with interstitial lung disease and lung adenocarcinoma. To date, no specific treatment is available. Here, the impact of wild-type (WT) SP-A1 or SP-A2 on the localization, oligomerization, and secretion of deleterious SP-A1 or SP-A2 variants is investigated. To achieve this, we used expression vectors carrying four previously described variations as well as a newly identified variation in SFTPA1 and SFTPA2 or WT sequences. Proteins were transiently expressed in HEK293T, and, after extraction, SP-A1 and SP-A2 were analyzed by Western blotting to assess their stability, ability to form oligomers, and secretion. In addition, the subcellular localization of these proteins in HEK293 cells was examined using immunofluorescence microscopy. Consistent with previous reports, we observed that all the variations impair SP-A1 or SP-A2 secretion. Localization of mutated proteins was also disrupted. Furthermore, all variations in SFTPA1 and SFTPA2 exhibited defects in oligomerization of mutated proteins, together with lower expression levels. Interestingly, coexpression of SP-A1 or SP-A2 WT resulted in an increased expression of the mutated proteins, restored a proper oligomerization profile, and partially restored SP-A secretion. This study reveals the beneficial effect of SP-A WT on oligomerization and secretion of mutant SP-A, suggesting that SP-A may be studied as a potential targeted treatment in interstitial lung disease linked to SP-A molecular variations.

Bronchodilators that relax airway smooth muscle cells (ASMCs) are essential for treating constrictive airway diseases such as asthma. However, the existing bronchodilators are often unable to control symptoms of severe asthmatic patients, leaving a pressing need to search for alternatives. Recent studies indicate that the transmembrane mechanosensitive channel, Piezo1, may provide a novel target for bronchodilation, as it mediates ASMC relaxation by means of calcium signaling and activation of large-conductance, calcium-activated potassium channels, and the Piezo1-specific agonist Yoda1 has been shown to reduce cell stiffness and traction force in cultured ASMCs after 24-hour incubation. Therefore, in this study, we further explored the potential of Yoda1 for inducing rapid ASMC relaxation and bronchodilation. We treated either cultured ASMCs or allergen-induced mouse models of asthma with Yoda1 at various doses and then assessed the resulting variations in cell stiffness, traction force, and molecular signaling of cultured ASMCs, as well as in airway resistance of the mouse models. We found that exposure to Yoda1 rapidly decreased cell stiffness; decreased traction force in association with induced calcium signaling and the activation of large-conductance, calcium-activated potassium channels in cultured ASMCs; and reduced airway resistance in methacholine-challenged mice in a dose-dependent manner. These results indicate that chemical activation of Piezo1 with specific agonist Yoda1 was, indeed, capable of inducing bronchodilation by relaxing ASMCs; thus, they provide insights into the development of Piezo1 agonist-based novel bronchodilators for treating constrictive airway disorders such as asthma.

Trisomy of chromosome 21 (TS21), also known as Down syndrome (DS), increases pediatric mortality risk due to respiratory syncytial virus (RSV) by ninefold. However, the underlying immunological basis remains unclear. To define the biological implications of TS21 in airway epithelial cells (AECs), the primary site of respiratory virus entry and host defense, in this study we investigated RSV-induced responses in primary nasal AECs from pediatric donors of euploid and trisomic cells. We used comprehensive approaches to assess baseline IFN-JAK-STAT signaling; viral infectivity; and the production of Type III IFN/λ1, proinflammatory cytokines, and chemokines before and after RSV exposure. TS21 AECs exhibited baseline hyperactive IFN-JAK-STAT signaling and reduced RSV infectivity but also showed impaired Type III IFN responses during viral infection. Furthermore, TS21 AECs demonstrated a robust proinflammatory state, with upregulated leukocyte/neutrophil chemotaxis pathways and heightened CXCL5/CXCL10 production before and after RSV exposure. This pattern was recapitulated in infants with DS who had severe viral bronchiolitis, exhibiting a dysregulated airway immune response characterized by diminished Type III IFN and excessive CXCL5/CXCL10 production. Our results suggest that RSV severity in DS is not due to enhanced viral infectivity but, rather, to dysregulated airway proinflammatory responses, offering new therapeutic opportunities to mitigate the severity of RSV infection in children with DS.

Cellular senescence has been implicated in the pathogenesis of chronic obstructive pulmonary disease (COPD). The mechanisms of senescence in the bronchial epithelium, however, remain largely unknown. In this study, we aimed to elucidate whether cellular senescence in COPD epithelial cells contributes to the pathogenesis of the disease and investigated the potential molecular mechanisms involved. Single-cell RNA sequencing was performed on well-differentiated primary bronchial epithelial cells from patients with COPD and healthy subjects. We evaluated the abundance and distribution of senescence markers in key epithelial differentiated subtypes and senescence-associated secretory phenotype involved in airway epithelial dysfunction. The effects of IFN-pathway inhibitors on cellular senescence were also investigated. There was increased expression of cellular senescence genes in the COPD cohort, which was predominantly in basal and club cells. Enhanced expression of cellular senescence markers, p16 and p21, was observed in COPD cultures, which was histologically confirmed in the lung tissue of patients with COPD. There was also a notable increase in IFN-β and IFN-γ. Senescence-associated secretory phenotype productions were increased in COPD and were attenuated by JAK-STAT or cGAS-STING pathway inhibitors (baricitinib or C-176). These inhibitors also effectively suppressed expression of senescence markers. COPD bronchial epithelium displays a senescence-driven phenotype which is mediated by Type I/II IFNs. Inhibition of JAK-STAT or STING-cGAS IFN pathways may represent targets to alleviate cellular senescence and chronic inflammation in COPD.