American Journal of Respiratory Cell and Molecular Biology最新文献

A subset of severe asthma is characterized by neutrophilic airway inflammation in which epithelial activation of the NLRP3 inflammasome pathway is implicated. Recent reports link SERPINB10 to neutrophil activation in inflammatory disease. We hypothesized that SERPINB10 contributes to neutrophilic inflammation in asthma. Since viral infection triggers airway neutrophilia in asthma, we sensitized mice with house dust mite (HDM) and challenged them with HDM and poly(I:C), a viral double-stranded RNA analog. Compared to wild-type mice, Serpinb10^-/- mice exhibited reduced neutrophil counts in bronchoalveolar lavage cells and alleviated inflammatory cell infiltration around airways. Expression of inflammatory cytokines such as Il-1β and Il-6 was also decreased in lung tissues from Serpinb10^-/- mice. In cultured HBE cells, SERPINB10 knockdown decreased IκBα phosphorylation and suppressed poly(I:C)-induced expression of IL-1β and IL-6. Moreover, the expression of NLRP3 and pro-IL-1β in lung tissues of Serpinb10^-/- mice was decreased. Conversely, SERPINB10 overexpression enhanced IL-1β and IL-6 expression in HBE cells, which was blocked by either an IκBα phosphorylation inhibitor or an NLRP3 inhibitor. Of note, SERPINB10 expression in bronchial brushings from non-eosinophilic asthma patients was enhanced and significantly correlated with the severity of airflow limitation, and the expression of NLRP3, IL-1β, and IL-6. Altogether, SERPINB10 promotes IL-1β and IL-6 expression by upregulating NF-κB and NLRP3 signaling in airway epithelial cells, thereby driving neutrophilic airway inflammation in asthma. SERPINB10 is a potential therapeutic target for airway neutrophilia in asthma.

Checkpoint inhibitor pneumonitis (CIP) is a highly morbid complication of immune checkpoint immunotherapy, characterized by acute lung injury leading, in severe cases, to hypoxic respiratory failure and death. CIP incidence in lung cancer is high (10-15%). Yet, the pathophysiology of CIP is poorly understood. To investigate the mechanisms underlying alveolar inflammation in patients with CIP, human bronchoalveolar fluid (BALF) samples from control and CIP patients were analyzed using flow cytometry, single cell RNA sequencing (scRNA seq), and ELISA. Findings were validated using multiple external cohorts. In vitro experiments and in vivo rodent models were employed to investigate the mechanisms driving alveolar inflammation in CIP. Analysis of scRNA seq and flow cytometry data demonstrated increased macrophages in patients with CIP compared to controls. Several distinct pro-inflammatory alveolar macrophage subsets were increased in CIP. CIP macrophages expressed increased chemokine ligand-18 (CCL18) at the transcript (scRNAseq), cellular (flow cytometry) and secreted protein (BALF ELISA) level. BALF CCL18 levels were associated with clinical CIP severity. CCL18 over-expression in mice promoted lung inflammation that phenocopied human CIP, including upregulation of pro-inflammatory macrophage subsets. These findings suggest that BALF macrophages and CCL18 protein levels are increased in patients with CIP and associate with greater CIP severity. Additionally, CCL18 promotes lung inflammation in mice that mimics human CIP, suggesting a causal role for CCL18 in CIP.

Chronic obstructive pulmonary disease (COPD) is a major contributor to global mortality rates, yet the cell-specific mechanisms underlying its pathobiology remain poorly understood, particularly in mild disease stages. Single-cell profiles of lung tissues from individuals with mild to moderate COPD or control lungs were analyzed using Microwell-seq. Transcriptomic findings were validated using microfluidic single-cell RNA sequencing of murine lungs, high-throughput single-nucleus total RNA sequencing (snHH-seq) of human lung tissues from severe COPD, spatial transcriptomics, functional in vitro models, and immunostaining of human lung samples. An increased subpopulation, termed interstitial COPD-associated macrophages (ICM), was identified, with transcriptional evidence of anti-inflammatory activity and reduced the transcription of proteins associated with elastase secretion in mild to moderate COPD. Comprehensive analysis of single-cell datasets revealed enhanced expression of Secretoglobin 3A2 (SCGB3A2) and macrophage receptor with collagenous structure (MARCO) across epithelial secretory cells and interstitial macrophages. Transcriptomic data demonstrated that MARCO activation was pivotal for phenotypic changes in interstitial macrophages (IM) transitioning to alveolar macrophages (AM). Spi-1 proto-oncogene (SPI1) transcription factor levels aligned with the MARCO transcriptome in ICM derived from COPD. In mild to moderate COPD, secretory cells play protective roles by regulating ICM through the SCGB3A2-MARCO pathway. Targeting ICM for COPD treatment may preserve the anti-inflammatory interstitial environment in patients.

Infection by influenza A virus (IAV) and other viruses causes disease exacerbations in chronic obstructive pulmonary disease (COPD). Immune responses are blunted in COPD, a deficit compounded by current standard-of-care glucocorticosteroids (GCS) to further predispose patients to life-threatening infections. The immunosuppressive effects of elevated transforming growth factor-β (TGF-β) in COPD may amplify lung inflammation during infections while advancing fibrosis. In the present study, we investigated potential repurposing of pirfenidone, currently used as an antifibrotic for idiopathic pulmonary fibrosis, as a nonsteroidal treatment for viral exacerbations of COPD. Murine models of lung-specific TGF-β overexpression or chronic cigarette smoke exposure with IAV infection were used. Pirfenidone was administered daily by oral gavage commencing pre- or postinfection, and inhaled pirfenidone and GCS treatment preinfection were also compared. Tissue and BAL were assessed for viral replication, inflammation, and immune responses. Overexpression of TGF-β enhanced the severity of IAV infection, contributing to unrestrained airway inflammation. Mechanistically, TGF-β reduced innate immune responses to IAV by blunting IFN-regulated gene expression and suppressing production of antiviral proteins. Prophylactic pirfenidone administration opposed these actions of TGF-β, curbing IAV infection and airway inflammation associated with TGF-β overexpression and cigarette smoke-induced COPD. Notably, inhaled pirfenidone caused greater inhibition of viral loads and inflammation than inhaled GCS. These proof-of-concept studies demonstrate that repurposing pirfenidone and employing a preventative strategy may yield substantial benefit over antiinflammatory GCS in COPD. Pirfenidone can mitigate damaging viral exacerbations without attendant immunosuppressive actions and merits further investigation, particularly as an inhaled formulation.

Extracellular vesicles (EVs) are membrane-bound particles secreted by cells with emerging roles in intercellular communication during tissue homeostasis and disease. Although EVs are abundant in respiratory biofluids, their cellular sources, critical cargos, and functions in the airway remain poorly understood. To determine how EV populations are changed in respiratory fluids during a chronic tissue inflammatory response, nasal EVs were assayed in 23 control participants and 22 participants with aspirin-exacerbated respiratory disease (AERD). Nasal lining fluid from participants was found to contain abundant EVs by electron microscopy and tunable resistive pulse sensing. Subset-specific EV subpopulations defined by the macrophage marker CD14 or the epithelial marker CD133/1 were increased in participants with AERD. To test how EVs change during an acute exacerbation, nasal lining fluid EVs were assessed in participants with AERD, who were repeatedly sampled during an aspirin-induced respiratory reaction. The abundance of several EV subpopulations dynamically correlated with concentrations of cysteinyl leukotrienes and tryptase in AERD nasal lining fluid. Together, these data implicate EVs in a dynamic signaling network that drives tissue inflammation during aspirin-induced type 2 immune activation in AERD.