American journal of physiology. Lung cellular and molecular physiology最新文献

Metabolic abnormalities in pulmonary endothelial cells are implicated in pulmonary hypertension (PH) while increasing evidence shows the influence of diabetes on progressing PH. In this study, we examined the effect of type 2 diabetes on hypoxia-induced PH and investigated its molecular mechanisms using hypoxia-induced diabetic male mice. Chronic hypoxia led to a more severe PH in type 2 diabetic mice than in control mice. Next, we compared gene expression patterns in isolated pulmonary endothelial cells (MPECs) from control mice in normoxia (CN), diabetic mice in normoxia (DN), control mice exposed to hypoxia (CH), and diabetic mice exposed to hypoxia (DH). The results showed that expression levels of 27 mRNAs, out of 92 mRNAs, were significantly different among the four groups. Two glycolysis-related proteins, GAPDH and HK2, were increased in MPECs of DH mice compared to those in DN or CH mice. In addition, the levels of pyruvate and lactate (glycolysis end products) were significantly increased in MPECs of DH mice, but not in CH mice, compared to MPECs of CN mice. Augmentation of glycolysis by terazosin exacerbated hypoxia-induced PH in CH mice but not in DH mice. On the contrary, inhibiting GAPDH (a key enzyme of the glycolytic pathway) by koningic acid ameliorated hypoxia-induced PH in DH mice but had no effect in CH mice. These data suggest that enhanced glycolysis in diabetic mice is involved in severe hypoxia-induced PH, and glycolysis inhibition is a potential target to reduce the severe progression of PH in diabetic patients.

Background Clinical monitoring of pulmonary edema due to vascular hyperpermeability in ARDS poses significant clinical challenges. Presently, no biological or radiological markers are available for quantifying pulmonary edema. Our aim was to phenotype pulmonary edema and pulmonary vascular permeability in patients with COVID-19 ARDS. Methods Transpulmonary thermodilution measurements were conducted in 65 COVID-19 ARDS patients on the day of intubation to determine extravascular lung water index (EVLWi) and pulmonary vascular permeability index (PVPi). In parallel, ventilatory parameters, clinical outcomes, the volume of lung opacity measured by chest CT, and plasma proteomics (358 unique proteins) were compared between tertiles based on the EVLWi and PVPi. Regression models were used to associate EVLWi and PVPi with plasma, radiological, and clinical parameters. Computational pathway analysis was performed on significant plasma proteins in the regression models. Results Patients with the highest EVLWi values at intubation exhibited poorer oxygenation parameters and more days on the ventilator. Extravascular lung water strongly correlated with the total volume of opacity observed on CT(r=0.72), while the PVPi had weaker associations with clinical and radiological parameters. Plasma protein concentrations demonstrated a stronger correlation with PVPi than with EVLWi. The highest tertile of PVPi was associated with proteins linked to the acute phase response (cytokine and chemokine signaling) and extracellular matrix turnover. Conclusions In the clinical setting of COVID-19 ARDS, pulmonary edema (EVLWi) can be accurately quantified through chest CT and parallels deterioration in ventilatory parameters and clinical outcomes. Vascular permeability (PVPi) is strongly reflected by inflammatory plasma proteins.

The combination of elexacaftor/tezacaftor/ivacaftor (ETI, Trikafta) reverses the primary defect in Cystic Fibrosis (CF) by improving CFTR mediated Cl^- and HCO₃^- secretion by airway epithelial cells (AEC), leading to improved lung function and less frequent exacerbations and hospitalizations. However, studies have shown that CFTR modulators like ivacaftor, a component of ETI, has numerous effects on CF cells beyond improved CFTR channel function. Because little is known about the effect of ETI on CF AEC gene expression we exposed primary human AEC to ETI for 48 hours and interrogated the transcriptome by RNA-seq and qPCR. ETI increased CFTR Cl^- secretion, and defensin gene expression (DEFB1) an observation consistent with reports of decreased bacterial burden in the lungs of people with CF (pwCF). ETI decreased MMP10 and MMP12 gene expression, suggesting that ETI may reduce proteolytic induced lung destruction in CF. ETI also reduced the expression of the stress response gene heme oxygenase (HMOX1). qPCR analysis confirmed DEFB1, HMOX1, MMP10 and MMP12 gene expression results observed by RNA-seq. Gene pathway analysis revealed that ETI decreased inflammatory signaling, cellular proliferation and MHC Class II antigen presentation. Collectively, these findings suggest that the clinical observation that ETI reduces lung infections in pwCF is related in part to drug induced increases in DEFB1, and that ETI may reduce lung damage by reducing MMP10 and MMP12 gene expression. Moreover, pathway analysis also identified several other genes responsible for the ETI induced reduction in inflammation observed in pwCF.

Objectives: Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease which is usually diagnosed late in advanced stages. Little is known about the subclinical development of IPF. We previously generated a mouse model with conditional Nedd4-2 deficiency (Nedd4-2^-/-) that develops IPF-like lung disease. The aim of this study was to characterize the onset and progression of IPF-like lung disease in conditional Nedd4-2^-/- mice by longitudinal micro-computed tomography (CT).

Methods: In vivo micro-CT was performed longitudinally in control and conditional Nedd4-2^-/- mice at 1, 2, 3, 4 and 5 months after doxycycline induction. Further, terminal in vivo micro-CT followed by pulmonary function testing and post mortem micro-CT was performed in age-matched mice. Micro-CT images were evaluated for pulmonary fibrosis using an adapted fibrosis scoring system. Histological assessment of lung collagen content was conducted as well.

Results: Micro-CT is sensitive to detect onset and progression of pulmonary fibrosis in vivo and to quantify distinct radiological IPF-like features along disease development in conditional Nedd4-2^-/- mice. Nonspecific interstitial alterations were detected from 3 months, whereas key features such as honeycombing-like lesions were detected from 4 months onwards. Pulmonary function correlated well with in vivo (r=-0.738) and post mortem (r=-0.633) micro-CT fibrosis scores and collagen content.

Conclusion: Longitudinal micro-CT enables in vivo monitoring of onset and progression and detects radiologic key features of IPF-like lung disease in conditional Nedd4-2^-/- mice. Our data support micro-CT as sensitive quantitative endpoint for preclinical evaluation of novel antifibrotic strategies.

Streptococcus pneumoniae is a leading cause of community-acquired pneumonia. Intercellular adhesion molecule-1 (ICAM-1) is an adhesion molecule that is highly expressed on the pulmonary capillary endothelium, alveolar epithelium and other cell types within the lung. ICAM-1 plays important roles in leukocyte adhesion, migration, and motility. To determine the contributions of ICAM-1 to bacterial clearance and leukocyte kinetics during pneumonia, mice were inoculated with S. pneumoniae and evaluated 1, 4 and 7 days later. Our results show that Icam1^-/-mice have a greater number of viable bacteria within the lung at each time point. The impaired clearance observed in Icam1^-/- mice was not due to an impediment in leukocyte recruitment. In fact, Icam1^-/- mice had a greater number of neutrophils and recruited inflammatory macrophages in the lung tissue and the alveoli/airways on day 7. In contrast, fewer alveolar macrophages were present in the BAL of Icam1^-/-mice. The loss of body weight and the concentrations of inflammatory mediators in the BAL were also significantly greater in Icam1^-/- mice. Mechanistic studies to understand the defect in clearance show that neutrophils and macrophage subpopulations had no defect in phagocytosis or acidification of phagosomes. RNA sequencing reveals many differences in gene expression, but no suggestion of a defect in phagocytosis or killing. Thus, that ICAM-1 is necessary for the clearance of S. pneumoniae and for the resolution of pneumonia, but is not required for the recruitment of neutrophils or inflammatory macrophages into the pneumonic lung parenchyma or the alveoli/airways during S. pneumoniae-induced pneumonia.

Asthma in the elderly is being recognized as more severe, resistant to standard therapies, and having greater morbidity. Therefore, it comes important to understand the impact of aging-associated airway structure and function changes towards pathogenesis of asthma in the elderly. Here, airway smooth muscle plays important roles in airway hyperreactivity and structural remodeling. The role of smooth muscle in asthma can be modulated by growth factors (including neurotrophins such as brain-derived neurotrophic factor (BDNF)) and pro-inflammatory senescence factors. In this study, we investigated aging effects on airway hyperreactivity, structural remodeling, inflammation, and senescence in a mouse model of allergic asthma. C57BL/6J wildtype mice or smooth muscle-specific BDNF knockout mice at 4, 18 and 24 months of age were intranasally exposed to mixed allergens (ovalbumin, aspergillus, Alternaria, and house dust mite) over 4 weeks. Assessing lung function by FlexiVent, we found that compared with 4 month old mice, 18 and 24 month old C57BL/6J mice showed decreased airway resistance and increased airway compliance after PBS or MA treatment. Deletion of smooth muscle BDNF blunted airway hyperreactivity in aged mice. Lung histology analysis revealed that aging increased bronchial airway thickness and decreased lung inflammation. Multiplex assays showed that aging largely reduced allergen-induced lung expression of proinflammatory chemokines and cytokines. By immunohistochemistry staining, we found that aging increased bronchial airway expression of senescence markers, including p21, phospho-p53 and phospho-gH2A.X. Our data suggest that aging associated increase of airway senescence in the context of allergen exposure may contribute to asthma pathology in the elderly.

Respiratory depression that diminishes oxygen delivery to the brain is the most dangerous effect of opioid drugs. While plethysmography is a valuable tool to examine drug-induced changes in respiration, the primary cause of brain abnormalities induced by opioids is the global decrease in brain oxygen levels. The primary goal of this review is to provide an overview and discussion on fluctuations in brain oxygen levels induced by opioids, with a focus on heroin and fentanyl. To evaluate fluctuations in brain oxygen levels we used oxygen sensors coupled with high-speed amperometry in awake, freely moving rats. First, we provide an overview of brain oxygen responses induced by natural physiological stimuli and discuss the mechanisms regulating oxygen entry into brain tissue. Then, we present data on brain oxygen responses induced by heroin and fentanyl and review their underlying mechanisms. These data allowed us to compare the effects of these drugs on brain oxygen regarding their latency, potency, time-dependency, and potential lethality at high doses as well as their relationships with peripheral oxygen responses. We also discuss data on the effects of naloxone on brain oxygen responses induced by heroin and fentanyl in the paradigms of both the pre-treatment and treatment, when naloxone is administered at different times after the primary opioid drug. Although most data discussed were obtained in rats, they may have clinical relevance for understanding the mechanisms underlying the physiological effects of opioids and developing rational treatment strategies to decrease acute lethality and long-term health complications of opioid misuse.

The IPF lung contains mesenchymal progenitor cells (MPCs) that display durable activation of oncogenic signaling and cell-autonomous fibrogenicity in vivo. Prior work identified a CD44/Brg1/PRMT5 nuclear regulatory module in IPF MPCs that increased expression of genes positively regulating pluripotency and self-renewal. Left unanswered is how IPF MPCs evade negative regulation of self-renewal. Here we sought to identify mechanisms disabling negative regulation of self-renewal in IPF MPCs. We demonstrate that expression of the tumor suppressor genes rbl1 and pten is decreased in IPF MPCs. The mechanism involves CD44-facilitated association of the chromatin remodeler Brg1 with the histone modifying methyltransferase PRMT5. Brg1 enhances chromatin accessibility leading to PRMT5-mediated methylation of H3R8 and H4R3 on the rbl1 and pten genes, repressing their expression. Genetic knock-down or pharmacological inhibition of either Brg1 or PRMT5 restored RBL1 and PTEN expression, reduced IPF MPC self-renewal in vitro and inhibited IPF MPC-mediated pulmonary fibrosis in vivo. Our studies indicate that the CD44/Brg1/PRMT5 regulatory module not only functions to activate positive regulators of pluripotency and self-renewal, but also functions to repress tumor suppressor genes rbl1 and pten. This confers IPF MPCs with the cancer-like property of cell-autonomous self-renewal providing a molecular mechanism for relentless fibrosis progression in IPF.

Pulmonary arterial hypertension (PAH) is a progressive, chronic, and incurable inflammatory pulmonary vascular disease characterized by significant sex bias and largely unexplored microbial-associated molecular mechanisms that may influence its development and sex prevalence across various subgroups. PAH can be subclassified as idiopathic, heritable, or associated with conditions such as connective tissue diseases, congenital heart defects, liver disease, infections, and chronic exposure to drugs or toxins. During PAH progression, lung vascular endothelial cells (ECs) undergo dramatic morphofunctional transformations in response to acute and chronic inflammation. These transformations include the appearance and expansion of abnormal vascular cell phenotypes such as those derived from apoptosis-resistant cell growth and endothelial-to-mesenchymal transition (EndoMT). Compelling evidence indicates that these endothelial phenotypes seem to be triggered by chronic lung vascular injury and dysfunction, often characterized by reduced secretion of vasoactive molecules like nitric oxide (NO) and exacerbated response to vasoconstrictors such as Endothelin-1 (ET-1); both long-term known contributors of PAH pathogenesis. This review sheds light on the mechanisms of EC dysfunction, apoptosis, and EndoMT in PAH, aiming to unravel the intricate interactions between ECs, pathogens, and other cell types that drive the onset and progression of this devastating disease. Ultimately, we hope to provide an overview of the complex functions of lung vascular ECs in PAH, inspiring novel therapeutic strategies that target these dysfunctional cells to improve the treatment landscape for PAH, particularly in the face of current and emerging global pathogenic threats.

Cystic fibrosis (CF) is a genetic disorder characterized by recurrent airway infections, inflammation, impaired mucociliary clearance, and progressive decline in lung function. The disease may start in the small airways; however, this is difficult to prove due to the limited accessibility of the small airways with the current single-photon mucociliary clearance assay. Here, we developed a dynamic positron emission tomography assay with high spatial and temporal resolution. We tested that mucociliary clearance is abnormal in the small airways of newborn cystic fibrosis pigs. Clearance of [⁶⁸Ga]-tagged macroaggregated albumin from small airways started immediately after delivery and continued for the duration of the study. Initial clearance was fast but slowed down a few minutes after delivery. Cystic fibrosis pigs' small airways cleared significantly less than non-CF pigs' small airways (non-CF 25.1 ± 3.1% vs. CF 14.6 ± 0.1%). Stimulation of the cystic fibrosis airways with the purinergic secretagogue uridine-5'-triphosphate (UTP) further impaired clearance (non-CF with UTP 20.9 ± 0.3% vs. CF with UTP 13.0 ± 1.8%). None of the cystic fibrosis pigs treated with UTP (n = 6) cleared more than 20% of the delivered dose. These data indicate that mucociliary clearance in the small airways is fast and can easily be missed if the assay is not sensitive enough. The data also indicate that mucociliary clearance is impaired in the small airways of cystic fibrosis pigs. This defect is exacerbated by stimulation of mucus secretions with purinergic agonists.NEW & NOTEWORTHY We developed a novel positron emission tomography scan assay with unprecedented temporal and spatial resolution to measure mucociliary clearance in the small airways. We proved a long-standing but unproven assertion that mucociliary clearance is inherently abnormal in the small airways of newborn cystic fibrosis piglets that are otherwise free of infection or inflammation. This technique can be easily extended to other airway diseases such as asthma, idiopathic pulmonary fibrosis, or chronic obstructive pulmonary disease.