American Journal of Respiratory Cell and Molecular Biology最新文献

Alterations in mitochondrial structure and function contribute to vascular smooth muscle cell (VSMC) phenotypic switching and are causally linked to pulmonary arterial hypertension (PAH) pathogenesis. The PINK1/Parkin-mediated mitophagy pathway is a key mitochondrial quality control program by which defective mitochondria are targeted for removal. The role of PINK1/Parkin-mediated mitophagy in VSMC phenotypic switching and PAH pathogenesis is not known. We sought to evaluate if PINK1/Parkin-induced mitophagy modulates VSMC phenotypic switching and contributes to PAH. Mitophagy and PINK1/Parkin expression were evaluated in human PAH lungs and pulmonary artery smooth muscle cells (PASMCs). PINK1 and Parkin were silenced in human and mouse primary PASMCs, and global PINK1 and Parkin knockout mice were used. After silencing of PINK1 and Parkin, PASMC proliferation and apoptosis were measured, and experimental pulmonary hypertension was evaluated after exposure to hypoxia. Parkin and PINK1 levels were reduced in the pulmonary vasculature or PASMCs from PAH lungs, accompanied by decreased mitophagy. PINK1 and Parkin knockout animals had an exaggerated pulmonary hypertension phenotype upon exposure to hypoxia. Genetic silencing of PINK1 and Parkin in human and mouse PASMCs led to increased proliferation and apoptosis resistance. We conclude that reduced PINK1/Parkin-induced mitophagy contributes to PASMC phenotypic switching and exacerbates PAH.

Asthma prevalence and severity differs between male and female individuals across the lifespan. Prepubescent boys are more likely to experience asthma, but girls are disproportionately affected after puberty, with greater symptom burden and decreased type 2 inflammation. However, because the human male and female genomes are almost identical, it is especially difficult to identify differentially expressed genes by sex to account for differences in disease susceptibility and manifestations without large sample sizes. Although several genes and genetic polymorphisms lead to sex-specific effects in asthma risk, the effects of sex-biased gene expression on clinical features within patients with asthma remain understudied. In this study, we characterized gene expression differences between female and male individuals through meta-analysis of transcriptomes of blood samples from adult patients with and without asthma in a large gene expression database (n = 3,639; 56% female). A separate, local validation cohort (n = 132; 78% female) identified clinical correlations with expression levels of sex-biased expressed genes. We identified 61 genes differentially expressed by sex in circulating immune cells that are unique to adult subjects with asthma and correlate with important clinical features of asthma. These genes are implicated in lymphocyte proliferation and differentiation as well as innate and adaptive immune allergic responses in the lung. In addition, similar transcriptional meta-analyses of pediatric asthma demonstrated age-specific gene expression effects. In summary, our findings support a sex-specific inflammatory architecture in asthma that is associated with differential gene expression in the blood and is age-specific.

Sampling nasal lining fluid (NLF) via nasosorption is minimally invasive and well tolerated, but the feasibility of assessing the nasal microbiome using these samples is unknown. However, low biomass makes airway samples particularly susceptible to issues related to contaminant DNA. For this study, we collected nasal swabs and NLF from adult volunteers. DNA was extracted from a mock microbial community and NLF using a column-based kit (ZymoBIOMICS), a precipitation-based kit (Qiagen), or a previously published precipitation-based method. Quality and quantity of DNA was assessed, and short-read 16S rRNA sequencing was performed to assess feasibility and extraction bias. An optimized methodology was used to extract DNA from NLF and nasal swabs, and long-read 16S rRNA sequencing was performed to compare microbial profiles between NLF and nasal swabs. All extraction methods recovered DNA from the mock community, but only precipitation-based methods yielded sufficient DNA from NLF. Extraction methodologies significantly affected microbial profiles, with mechanical lysis needed to minimize bias. Profiles obtained from NLF and swabs were comparable with long-read sequencing. Our findings demonstrate the feasibility of profiling the nasal microbiome using NLF and validated two extraction methodologies as suitable for full-length 16S rRNA sequencing of low-biomass respiratory samples. Our data demonstrate the importance of unbiased DNA extraction methodologies in low-biomass respiratory samples. In addition, we demonstrated NLF may be an appropriate surrogate for swabs to assess the nasal microbiome.

Severe pleural space inflammation associated with exudative pleural effusions leads to the development of pleural fibrosis (PF). Pathological tissue remodeling in PF is associated with profibrotic changes in the pleural mesothelium and neoangiogenesis within the fibrotic region. However, the factors that promote these processes remain poorly understood. This study investigates the role of extracellular vesicles (EVs) in the development and progression of PF, focusing on mesothelial-to-mesenchymal transition and neoangiogenesis. Human pleural mesothelial cells (HPMCs) were treated with coagulation proteases FXa (factor Xa) and thrombin, and EV production was quantified using nanoparticle tracking analysis. The functional relevance of these EVs was assessed by evaluating their ability to promote a profibrotic phenotype in HPMCs and induce tube formation in endothelial cells. FXa and thrombin treatments significantly increased EV generation from HPMCs via PAR (protease-activated receptor)-mediated cell signaling. Our studies showed that these EVs primed HPMCs toward a profibrotic phenotype and enhanced tube formation in endothelial cells. Further investigations in preclinical mouse models of PF revealed elevated EV levels in pleural fluids from injury-induced mice, compared with saline control mice. In clinical specimens, exudative pleural effusions from patients with empyema and parapneumonic effusions exhibited significantly elevated EV numbers compared with transudative effusions from patients with congestive heart failure. More importantly, EVs isolated from exudative effusions promoted a profibrotic phenotype in naive HPMCs and enhanced tube formation similar to the effects observed with FXa- and thrombin-generated EVs. These findings offer new insights into PF pathogenesis by identifying EVs as previously unknown contributors that modulate mesothelial-to-mesenchymal transition and neoangiogenesis.

Chronic obstructive pulmonary disease (COPD) is characterized by progressive airflow limitation and emphysema development, associated with enhanced tissue destruction and defective repair. Supporting cells in the alveolar niche play a crucial role in guiding the activation of alveolar epithelial progenitor cells during repair. Despite their close anatomical proximity, understanding of the supportive role of the pulmonary microvascular endothelium in adult alveolar epithelial repair remains limited. We hypothesized that factors secreted by pulmonary endothelial cells support alveolar epithelial cell growth. Here, we report that human pulmonary microvasculature endothelial cells support murine and human alveolar organoid formation through paracrine signaling via the secretion of extracellular vesicles and soluble factors. Transcriptomic and proteomic analysis pinpointed human pulmonary microvasculature endothelial cell-derived BMP6 (bone morphogenetic protein 6) as a critical factor for alveolar organoid formation. BMP6 promoted alveolar epithelial cell growth, whereas function-blocking antibodies targeting BMP6 inhibited the beneficial effect of endothelial cells on murine alveolar organoid formation. Transcriptomic analysis revealed that BMP6 specifically enhances distal epithelial cell markers and increases Wnt signaling in epithelial progenitors. In contrast, BMP6 deficiency in mouse lungs was associated with reduced Wnt signaling and augmented oxidative stress signaling in murine lung tissue. Taken together, our findings highlight BMP6 as a key regulator of adult epithelial repair and suggest its potential as a therapeutic target for defective epithelial repair, particularly in individuals with early stages of COPD.