Pulmonology
Abstract
CFTR in the lung epithelium contributes to the secretion of a surface liquid layer that is essential to lung homeostasis and defense. The understanding of how liquid is secreted in the lung is derived largely from studies of the airway epithelium. Comparatively little is known about liquid secretion mechanisms in the alveolar epithelium, including its cellular source. To define which cell type drives alveolar liquid secretion, we generated transgenic mice that expressed a Cftr null allele in alveolar type 1 (AT1) cells, type 2 (AT2) cells, or both, then viewed liquid secretion in live alveoli using confocal microscopy of isolated, perfused lungs. Our findings show liquid secretion was blocked in alveoli of all three transgenic mice, indicating that both AT1 and AT2 cells contribute to alveolar liquid secretion. Cftr null expression in AT1 cells also blocked the secretion-mediated clearance of small particle and bacterial clusters from alveolar walls, indicating that AT1 cell CFTR contributes to alveolar defense. Together, these findings show alveolar liquid secretion depends on both AT1 and AT2 cell CFTR, and that CFTR in AT1 cells – a cell type not traditionally considered in liquid secretion mechanisms or CFTR-related lung diseases – contributes to lung liquid dynamics and host defense.
Authors
Sayahi Suthakaran, Sonya Homami, Deebly Chavez, Stephanie Tang, Sarah K.L. Moore, Chaya Sussman, Jimmy Zhang, Clemente J. Britto, Alice Prince, Alison J. May, Jaymin J. Kathiriya, Jaime L. Hook
Abstract
The mechanisms by which e-cigarette vaping (EV) affects lung health remain unclear. Clinical data from clusters of EV-associated lung injury indicate that EV damages distal lung parenchyma and increases vulnerability to second-hit injury, including respiratory viral infections. Using human lung endothelial and epithelial cells and precision-cut lung slices, we investigated the mechanisms underlying distal lung cell injury and repair triggered by brief (24-hour) EV exposure. Using RNA sequencing of lung tissue from Golden Syrian hamsters, we evaluated the persistence of lung stress responses (10 days after 5 days of EV exposure and determined the impact of EV on host defense against influenza A virus (IAV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections. EV disrupted the barrier function of human distal lung cells through JNK stress-response signaling, triggered autophagy with impaired autophagolysosomal degradation, suppressed mTOR signaling and cell proliferation, and culminated in apoptosis. Analysis of transcriptional responses in EV-exposed hamster lungs revealed persistent activation of pathways involving JNK signaling, autophagy, barrier dysfunction, tissue remodeling, and impaired Th1 immunity. EV pre-exposure increased the viral burden of SARS-CoV-2, downregulated antiviral genes (Ifit1, Isg15, Nfkbia), and altered Stat1 and Irf7 immune signaling, while amplifying oxidative stress and IL-12 signaling. These findings show that short-term EV exposure triggered stress-induced distal lung cell injury with persistent changes in antiviral immunity and molecular pathways associated with tissue remodeling. When sustained, as with habitual EV use, these alterations may increase susceptibility to respiratory viral infections and contribute to the development of chronic lung disease.
Authors
Tanner C. Rivera, Kelly S. Schweitzer, Christina F. Cornell, Jordan M. Nall, Nicholas Egersdorf, Courtney Moeder, Riley A. Cooney, Eszter K. Vladar, Steve D. Groshong, Gregory P. Downey, James P. Bridges, Richard Bowen, Hong Wei Chu, Irina Petrache
Abstract
Authors
Yudai Miyashita, Taisuke Kaiho, Yuriko Yagi, Taichi Nagano, Xin Wu, Yuanqing Yan, Haiying Sun, Carl Atkinson, GR Scott Budinger, Ankit Bharat, Chitaru Kurihara
Abstract
In α-1 antitrypsin (AAT) deficiency (AATD), emphysema is classically linked to protease-antiprotease imbalance caused by decreased antiprotease AAT due levels and function. This decrease is secondary to the impaired release of Z-AAT polymers from hepatocytes carrying Pi*Z, E342K mutation in SERPENA1 gene. Whether the accumulation of Z-AAT polymers in distal lungs contributes directly to emphysema pathogenesis has remained unexplored due to the lack of suitable model systems. We characterized lung injury and airspace enlargement in a Z-AAT–overexpressing murine model. We generated Z-AAT Serpina1Null mice overexpressing human (E342K) SERPENA1 in Serpina1Null mice and analyzed pulmonary phenotypes in young and aged animals, complemented by translational studies using primary cells, bronchoalveolar lavage fluid (BALf), and lung tissue from individuals who have never smoked and individuals with AATD. Young Z-AAT Serpina1Null mice accumulated Z-AAT polymers in hepatocytes, plasma, and BALf, exhibited spontaneous neutrophilic lung inflammation, increased alveolo-capillary permeability, and premature airspace enlargement, which was worse in older Z-AAT Serpina1Null mice. Moreover, Z-AAT polymers accumulated in alveolar type-2 epithelial (AT2) cells and lung macrophages, associated with endoplasmic reticulum (ER) stress, mitochondria dysfunction, and incomplete autophago-lysosomal fusion, which we recapitulated in lung samples from individuals with AATD. These findings support the pathogenic role of Z-AAT polymer accumulation in distal lung epithelium as a driver of epithelial, endothelial, and macrophage dysfunction linked to AATD emphysema.
Authors
Maria Magallón Serrano, Nazli Khodayari, William Bowers, Edward P. Manning, Xinran Liu, Jungnam Lee, Tammy O. Flagg, Regina Oshins, Aidan Griffin, Sahil Patel, Jorge E. Lascano, Divay Chandra, Susan M. Majka, Irina Petrache, Mark L. Brantly, Karina A. Serban
Abstract
Type 2 (T2) immune cells dominate the airways of mild-moderate asthma (MMA) patients with a more complex Type 1 (T1)-T2 mixed immune response evident in treatment-refractory severe asthma (SA). We hypothesized that comparing the transcriptomes of the airway epithelium of SA and MMA patients would reveal molecular signatures associated with more severe disease in the context of a complex immune response. Using our novel interpretable machine learning tool, SLIDE, meaningful latent factors (context-specific gene co-expression networks) were revealed that distinguished SA from MMA. Unexpectedly, an aberrant high expression of normally host-protective, membrane-tethered and IFN-inducible mucins, MUC1 and MUC4, was identified in SA. Gene networks in the significant latent factors discriminating SA from MMA corresponded to enrichment of a keratinization program in SA airways. Keratinization was marked by increased expression of the stress keratin KRT16, signifying squamous metaplasia suggesting adaptive reprogramming of the airway epithelium in response to chronic stress. These mucins and KRT16 were inversely associated with lung function in two separate asthma cohorts. Imaging of endobronchial biopsies revealed significantly higher KRT16 protein expression in SA compared to MMA that strongly correlated with MUC1 protein expression. Our study identifies dysregulated host-protective and maladaptive repair responses in SA distinguishing from MMA.
Authors
Sagar L. Kale, Augusta M. Vincent, Mark A. Ross, Isha Mehta, Michael J. Calderon, Richard P. Ramonell, Himanshu Setya, Jessica C. McCreary-Partyka, Huijuan Yuan, Stephanie A. Christenson, Prescott G. Woodruff, Mario Castro, Kaharu Sumino, Nizar N. Jarjour, Loren C. Denlinger, Benjamin Gaston, Eugene R. Bleecker, Deborah A. Meyers, Wendy C. Moore, Elliot Israel, Bruce D. Levy, David Mauger, Serpil Erzurum, Anthony Newbrough, Taylor J. Nee, Prabir Ray, Claudette M. St. Croix, Sally E. Wenzel, Jishnu Das, Anuradha Ray, Marc C. Gauthier
Abstract
Schistosomiasis is a common cause of pulmonary hypertension (PH) worldwide. It is known that adaptive immunity and specifically CD4 T cells are necessary for experimental disease pathogenesis. The lectin complement system is activated in those infected with schistosomiasis. We tested the hypothesis that lectin complement promotes Th2 CD4 T cell activation, leading to PH in a schistosomiasis exposure model. Wildtype and transgenic mice lacking mannose binding lectin (MBL), and bone marrow chimeras, were experimentally exposed to Schistosoma mansoni eggs. PH severity was assessed by hemodynamics and vascular remodeling, and CD4 T cell density and phenotype was assessed by flow cytometry. Wildtype recipients of MBL knockout bone marrow (BM) were protected from Schistosoma-induced PH. The protection from PH was associated with fewer Th2 CD4 T cells. In wildtype mice exposed to Schistosoma, CD4 T cells expression of MBL increased. MBL-deficient CD4 T cells had a suppressed Th2 phenotype when exposed to Schistosoma antigens. Mice with deficiency of C4, which functions downstream of MBL in the lectin complement pathway, were not protected from Schistosoma-PH. Mice lacking MBL were not protected from PH caused by hypoxia exposure. MBL in CD4 T cells promotes Schistosoma-induced PH.
Authors
Claudia Mickael, Dara C. Fonseca Balladares, Rahul Kumar, Michael H. Lee, Kevin Nolan, Linda Sanders, Katie J. Tuscan, Ramraj Prasad, Pilar Londono, Fernanda P. Oliveira, Kennedi B. Pyper, Ari B. Molofsky, Rubin M. Tuder, Kurt R. Stenmark, Brian B. Graham
Abstract
Pulmonary alveolar proteinosis (PAP) is a rare pulmonary syndrome characterized by impaired surfactant clearance, driven by dysfunctional cholesterol efflux in alveolar macrophages (AMs). However, the molecular determinants governing AM cholesterol homeostasis remain incompletely defined. Here, through a genome-wide CRISPR screen in foamy macrophages and bulk RNA sequencing of AMs from PAP patients, we identify DTX4 as a pivotal regulator of cholesterol efflux in AMs. In mice, AAV-mediated silencing of DTX4 led to excessive AM lipid accumulation, exacerbated proteinosis, increased lung opacities, and deteriorated pulmonary function. Similarly, DTX4 depletion in primary AMs impaired cholesterol efflux and promoted intracellular lipid deposition. Conversely, AM-specific overexpression of DTX4 in the Csf2ra–/– PAP model markedly alleviated lipid accumulation, mitigated alveolar proteinosis, restored lung densities, and rescued pulmonary function. Mechanistically, DTX4 stabilizes the GM-CSF receptor via an E3-independent interaction to sustain JAK2/STAT5 signaling, which reciprocally maintains DTX4 transcription. This positive-feedback loop drives PPARγ expression, and its disruption in PAP impairs cholesterol efflux, a defect partially reversible by ectopic PPARγ expression. Collectively, our findings identify DTX4 as a central orchestrator of AM cholesterol efflux and surfactant homeostasis, positioning it as a promising therapeutic target for PAP.
Authors
Zimu Wang, Jingwei Shi, Xu Ye, Xinye Xia, Huihui Zhu, Qi Li, Min Chen, Yichao Zhao, Yingwei Zhang, Mengshu Cao, Yonglong Xiao, Xinmei Huang
Abstract
Airway structural remodeling and hyperresponsiveness (AHR), hallmarks of asthma, are influenced by genetic variations and adverse exposures. While intrauterine perturbations in lung development have been linked to adult pulmonary disease, the developmental origins of these abnormalities remain poorly understood. Here, we provide evidence of genetic background playing a key role in this process. Using A/J and C57BL/6J mice known for their distinct susceptibility to AHR, we show that A/J embryos selectively develop an aberrant airway smooth muscle (SM) program and AHR in adulthood when exposed transiently to a vitamin A/retinoic acid (RA)-disrupted intrauterine environment in vivo by maternal BMS493 administration. Single-nuclei multiomics identified a mesenchymal cell population overactivating TGFβ targets in response to BMS selectively in A/J lungs. These cells, localized to sites of airway SM initiation and pSMAD2-3, exhibited robust BMS-mediated upregulation of SMAD2-3 targets, including regulators of SM program Pdgfra and Tnc. Functional analyses in vivo and cultured lungs showed aberrant SM formation in areas of overactive TGFβ of BMS-exposed lungs. These abnormalities were prevented by inhibiting TGFβ signaling in utero in RA-deficient embryos. These findings underscore how distinct genetic backgrounds respond to intrauterine perturbations that program airway structure and function, with potential lasting consequences in postnatal pulmonary function.
Authors
Takehiro Otoshi, Benjamin D. Kotton, Ayyappa K.S. Kameshwar, Yoshinori Seki, Zachary Cardell, Xiangyi Ke, Yuta Matsuno, Pooja Rajaram, Youn-Kyung Kim, Sarah M. Sharpton, Loredana Quadro, Wellington V. Cardoso, Masako Suzuki
Abstract
Hypercapnia, elevated carbon dioxide (CO2), is common in advanced chronic obstructive pulmonary disease (COPD) and predicts poor clinical outcomes. Traditionally considered a consequence of disease severity, hypercapnia may drive disease progression by promoting airway dysfunction. Here, we show that hypercapnia acts as an active stressor, driving airway smooth muscle (ASM) constriction through a stromal interaction molecule 1 (STIM1)-dependent pathway. Hypercapnia rapidly activates ERK, triggering sarcoplasmic reticulum calcium (Ca2+) release via phosphorylation of the inositol 1,4,5-trisphosphate receptor. ERK also induces nuclear translocation of the transcription factor c-Fos, enhancing STIM1 transcription. These responses were observed under both supraphysiological (~120 mmHg) and clinically relevant (50-60 mmHg) hypercapnia. Increased STIM1 abundance sustains store-operated Ca2+ entry (SOCE), amplifying ASM signaling. In mice, hypercapnia increased ASM and airway contractility in a STIM1-dependent manner. Human genetic analyses revealed noncoding STIM1 variants associated with reduced lung expression that were enriched in COPD patients. These variants correlated with lower airway resistance under normocapnia; however, this benefit was lost during hypercapnia, indicating a potential gene–environment interaction. Together, our findings position STIM1 as a key mechanistic node linking hypercapnia to Ca2+ dysregulation and airway obstruction, defining a CO2–ERK–STIM1–SOCE axis with translational relevance to chronic lung disease.
Authors
Masahiko Shigemura, Vitalii Kryvenko, Jennifer A. Pacheco, Megan J. Puckelwartz, Milos Aleksic, Natalia D. Magnani, Emma E. Thompson, Francisco Javier Martin-Romero, Eoin P. Cummins, Werner Seeger, Andreas Bräuninger, Lynn C. Welch, G.R. Scott Budinger, Emilia Lecuona, Laura A. Dada, Ankit Bharat, István Vadász, Murali Prakriya, Jacob I. Sznajder
Abstract
Authors
Sarah W. Robison, Jindong Li, Kristopher R. Genschmer, Liliana Viera, Jeremy B. Foote, Landon Wilson, W. Edward Swords, J. Edwin Blalock, Amit Gaggar, Xin Xu
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