Pulmonology
Abstract
Mutations in the gene (SFTPC) encoding surfactant protein C (SP-C) are associated with interstitial lung disease in children and adults. To assess the natural history of disease, we knocked-in a familial, disease-associated SFTPC mutation, L188Q [L184Q (LQ) in mice], into the mouse Sftpc locus. Translation of the mutant proprotein, proSP-CLQ, exceeded that of proSP-CWT in neonatal alveolar type 2 epithelial (AT2) cells and was associated with transient activation of oxidative stress and apoptosis leading to impaired expansion of AT2 cells during postnatal alveolarization. Differentiation of AT2 to AT1 cells was also inhibited in ex vivo organoid culture of AT2 cells isolated from LQ mice; importantly, treatment with antioxidant promoted alveolar differentiation. Upon completion of alveolarization, SftpcLQ expression was downregulated leading to resolution of chronic stress responses; however, the failure to restore AT2 cell numbers resulted in a permanent loss of AT2 cells that was linked to decreased regenerative capacity in the adult lung. Collectively, these data support the hypothesis that susceptibility to disease in adult LQ mice is established during postnatal lung development and provide a potential explanation for the delayed onset of disease in patients with familial pulmonary fibrosis.
Authors
Sneha Sitaraman, Emily P. Martin, Cheng-Lun Na, Shuyang Zhao, Jenna Green, Hitesh Deshmukh, Anne-Karina T. Perl, James P. Bridges, Yan Xu, Timothy E. Weaver
Abstract
The acute respiratory distress syndrome (ARDS) is a highly lethal condition that impairs lung function and causes respiratory failure. Mechanical ventilation maintains gas exchange in patients with ARDS, but exposes lung cells to physical forces that exacerbate lung injury. Our data demonstrate that mTOR complex 1 (mTORC1) is a mechanosensor in lung epithelial cells and that activation of this pathway during mechanical ventilation impairs lung function. We found that mTORC1 is activated in lung epithelial cells following volutrauma and atelectrauma in mice and humanized in vitro models of the lung microenvironment. mTORC1 is also activated in lung tissue of mechanically ventilated patients with ARDS. Deletion of Tsc2, a negative regulator of mTORC1, in epithelial cells impairs lung compliance during mechanical ventilation. Conversely, treatment with rapamycin at the time mechanical ventilation is initiated improves lung compliance without altering lung inflammation or barrier permeability. mTORC1 inhibition mitigates physiologic lung injury by preventing surfactant dysfunction during mechanical ventilation. Our data demonstrate that in contrast to canonical mTORC1 activation under favorable growth conditions, activation of mTORC1 during mechanical ventilation exacerbates lung injury and inhibition of this pathway may be a novel therapeutic target to mitigate ventilator-induced lung injury during ARDS.
Authors
Hyunwook Lee, Qinqin Fei, Adam Streicher, Wenjuan Zhang, Colleen Isabelle, Pragi Patel, Hilaire C. Lam, Antonio Arciniegas-Rubio, Miguel Pinilla-Vera, Diana P. Amador-Munoz, Diana Barragan-Bradford, Angelica Higuera-Moreno, Rachel K. Putman, Lynette Sholl, Elizabeth P. Henske, Christopher M. Bobba, Natalia Higuita-Castro, Emily M. Shalosky, R. Duncan Hite, John W. Christman, Samir N. Ghadiali, Rebecca M. Baron, Joshua A. Englert
Abstract
INTRODUCTION. Subjects recovering from COVID-19 frequently experience persistent respiratory ailments which are key elements of post-acute sequelae of SARS-CoV-2 infection (PASC); however, little is known about the underlying biological factors that may direct lung recovery and the extent to which these are affected by COVID-19 severity. METHODS. We performed a prospective cohort study of subjects with persistent symptoms after acute COVID-19, collecting clinical data, pulmonary function tests, and plasma samples used for multiplex profiling of inflammatory, metabolic, angiogenic, and fibrotic factors. RESULTS. Sixty-one subjects were enrolled across two academic medical centers at a median of 9 weeks (interquartile range 6-10) after COVID-19 illness: n=13 subjects (21%) mild/non-hospitalized, n=30 (49%) hospitalized/non-critical, and n=18 subjects (30%) hospitalized/intensive care (“ICU”). Fifty-three subjects (85%) had lingering symptoms, most commonly dyspnea (69%) and cough (58%). Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and diffusing capacity for carbon monoxide (DLCO) declined as COVID-19 severity increased (P<0.05), but did not correlate with respiratory symptoms. Partial least-squares discriminant analysis of plasma biomarker profiles clustered subjects by past COVID-19 severity. Lipocalin 2 (LCN2), matrix metalloproteinase-7 (MMP-7), and hepatocyte growth factor (HGF) identified by the model were significantly higher in the ICU group (P<0.05) and inversely correlated with FVC and DLCO (P<0.05), and were confirmed in a separate validation cohort (n=53). CONCLUSIONS. Subjective respiratory symptoms are common after acute COVID-19 illness but do not correlate with COVID-19 severity or pulmonary function. Host response profiles reflecting neutrophil activation (LCN2), fibrosis signaling (MMP-7), and alveolar repair (HGF) track with lung impairment and may be novel therapeutic or prognostic targets.
Authors
Hyung J. Chun, Elias Coutavas, Alexander B. Pine, Alfred I. Lee, Vanessa L. Yu, Marcus K. Shallow, Coral X. Giovacchini, Anne M. Mathews, Brian Stephenson, Loretta G. Que, Patty J. Lee, Bryan D. Kraft
Abstract
The main mechanisms underlying sexually dimorphic outcomes in neonatal lung injury are unknown. We tested the hypothesis that hormonal- or sex chromosome-mediated mechanisms interact with hyperoxia exposure to impact injury and repair in the neonatal lung. To distinguish sex differences caused by gonadal hormones versus sex chromosome complement (XX versus XY), we used the four core genotypes (FCG) mice and exposed them to hyperoxia (95% FiO2, PND1-4: saccular stage) or room air. This model generates XX and XY mice that each have either testes (with Sry, XXM or XYM) or ovaries (without Sry, XXF or XYF). Lung alveolarization and vascular development were more severely impacted in XYM and XYF compared to XXF and XXM mice. Cell cycle-related pathways were enriched in the gonadal or chromosomal females, while muscle-related pathways were enriched in the gonadal males, and immune-response related pathways were enriched in chromosomal males. Female gene signatures showed a negative correlation with human patients that developed BPD or needed oxygen therapy at 28 days. These results demonstrate that chromosomal sex and not gonadal sex impacted the response to neonatal hyperoxia exposure. The female sex chromosomal complement was protective and could mediate sex-specific differences in neonatal lung injury.
Authors
Sandra L. Grimm, Xiaoyu Dong, Yuhao Zhang, Alexandre F. Carisey, Arthur P. Arnold, Bhagavatula Moorthy, Cristian Coarfa, Krithika Lingappan
Abstract
Despite the high morbidity and mortality among patients with extensive cutaneous burns in the intensive care unit due to the development of acute respiratory distress syndrome, effective therapeutics remain to be determined. This is primarily because the mechanisms leading to acute lung injury (ALI) in these patients remain unknown. We test the hypothesis that cutaneous chemical burns promote lung injury due to systemic activation of neutrophils, in particular, toxicity mediated by the deployment of neutrophil extracellular traps (NETs). We also demonstrate the potential benefit of a peptidyl arginine deiminase 4 (PAD4) inhibitor to prevent NETosis and to preserve microvascular endothelial barrier function, thus reducing the severity of ALI in mice. Our data demonstrated that phenylarsine oxide (PAO) treatment of neutrophils caused increased intracellular Ca2+-associated PAD4 activity. A dermal chemical burn by lewisite or PAO resulted in PAD4 activation, NETosis, and ALI. NETs disrupted the barrier function of endothelial cells in human lung microvascular endothelial cell spheroids. Citrullinated histone 3 alone caused ALI in mice. Pharmacologic or genetic abrogation of PAD4 inhibited lung injury following cutaneous chemical burns. Cutaneous burns by lewisite and PAO caused ALI by PAD4-mediated NETosis. PAD4 inhibitors may have potential as countermeasures to suppress detrimental lung injury after chemical burns.
Authors
Ranu Surolia, Fu Jun Li, Zheng Wang, Mahendra Kashyap, Ritesh Kumar Srivastava, Amie M. Traylor, Pooja Singh, Kevin G. Dsouza, Harrison Kim, Jean-Francois Pittet, Jaroslaw W. Zmijewski, Anupam Agarwal, Mohammad Athar, Aftab Ahmad, Veena B. Antony
Abstract
Cigarette smoke (CS) is the main etiological factor in the pathogenesis of emphysema/Chronic Obstructive Pulmonary Disease (COPD), which is associated with abnormal epithelial-mesenchymal-transition (EMT). Previously, we have shown an association between circadian rhythms and CS-induced lung inflammation, and nuclear-heme-receptor α (REV-ERBα) acting as an anti-inflammatory target in both pulmonary epithelial cells and fibroblasts. We hypothesized that molecular clock REV-ERBα plays an important role in CS-induced circadian dysfunction and EMT alteration. C57BL/6J wild type (WT) and REV-ERBα heterozygous (Het) and knockout (KO) mice were exposed to CS for 30 days (sub-chronic) and 4 months (chronic), and WT mice were exposed to CS for 10 days with or without REV-ERBα agonist (SR9009) administration. Sub-chronic/chronic CS exposure caused circadian disruption and dysregulated EMT in the lungs of WT and REV-ERBα KO mice, both circadian and EMT dysregulation were exaggerated in REV-ERBα KO condition. REV-ERBα agonist, SR9009 treatment reduced acute CS-induced inflammatory response and abnormal EMT in the lungs. Further, REV-ERBα agonist (GSK4112) inhibited TGFβ/CS-induced fibroblast differentiation in human fetal lung fibroblast 1 (HFL-1).Thus, CS-induced circadian gene alterations and EMT activation are mediated through a Rev-erbα-dependent mechanism, which suggests activation of REV-ERBα as a novel therapeutic approach for smoking-induced chronic inflammatory lung diseases.
Authors
Qixin Wang, Isaac K. Sundar, Joseph H. Lucas, Thivanka Muthumalage, Irfan Rahman
Abstract
BACKGROUND. Whether airspace biomarkers add value to plasma biomarkers in studying ARDS is not well understood. Mesenchymal stromal cells (MSCs) are an investigational therapy for ARDS, and airspace biomarkers may provide mechanistic evidence for MSCs' impact in patients with ARDS. METHODS. We carried out a nested cohort study within a phase 2a safety trial of treatment with allogeneic MSCs for moderate to severe ARDS. Non-bronchoscopic bronchoalveolar lavage and plasma samples were collected 48 hours after study drug infusion. Airspace and plasma biomarker concentrations were compared between the MSC (n = 17) and placebo (n = 10) treatment arms, and correlation between the two compartments was tested. Airspace biomarkers were also tested for associations with clinical and radiographic outcomes. RESULTS. Compared to placebo, MSC treatment significantly reduced airspace total protein, angiopoietin-2 (Ang-2), interleukin-6 (IL-6), and soluble tumor necrosis factor receptor-1 concentrations. Plasma biomarkers did not differ between groups. Each 10-fold increase in airspace Ang-2 was independently associated with 6.7 fewer days alive and free of mechanical ventilation (95% CI -12.3 to -1.0, p = 0.023), and each 10-fold increase in airspace receptor for advanced glycation end-products (RAGE) was independently associated with a 6.6 point increase in day 3 radiographic assessment of lung edema score (95% CI 2.4 to 10.7, p = 0.004). CONCLUSIONS. MSCs reduced biological evidence of lung injury in patients with ARDS. Biomarkers from the airspaces provide additional value for studying pathogenesis, treatment effects, and outcomes in ARDS. TRIAL REGISTRATION. NCT02097641 FUNDING. National Heart, Lung, and Blood Institute
Authors
Katherine D. Wick, Aleksandra Leligdowicz, Hanjing Zhuo, Lorraine B. Ware, Michael A. Matthay
Abstract
Right ventricular (RV) fibrosis is a key feature of maladaptive RV hypertrophy and dysfunction and is associated with poor outcomes in pulmonary hypertension (PH). However, mechanisms and therapeutic strategies to mitigate RV fibrosis remain unrealized. Previously, we identified that cardiac fibroblast α7 nicotinic acetylcholine receptor (α7 nAChR) drives smoking induced RV fibrosis. Here we sought to define the role of α7 nAChR in RV dysfunction and fibrosis in the settings of RV pressure overload as seen in PH. We show that RV tissue from PH patients has increased collagen content and ACh expression. Using experimental rat model of PH, we demonstrate that RV fibrosis and dysfunction are associated with increases in ACh and α7 nAChR expression in the RV but not in the LV. In vitro studies show that α7 nAChR activation leads to an increase in adult ventricular fibroblast proliferation and collagen content mediated by a Ca2+/ epidermal growth factor receptor (EGFR) signaling mechanism. Pharmacological antagonism of nAChR decreases RV collagen content and improves RV function in the PH model. Further, mice lacking α7 nAChR exhibit improved RV diastolic function and have lower RV collagen content in response to persistently increased RV afterload, compared to wild-type controls. These finding indicate that enhanced α7 nAChR signaling is an important mechanism underlying RV fibrosis and dysfunction, and targeted inhibition of α7 nAChR is a novel therapeutic strategy in the setting of increased RV afterload.
Authors
Alexander Vang, Denielli da Silva Gonçalves Bos, Ana Fernandez-Nicolas, Peng Zhang, Alan R. Morrison, Thomas J. Mancini, Richard T. Clements, Iuliia Polina, Michael W. Cypress, Bong Sook Jhun, Edward Hawrot, Ulrike Mende, Jin O-Uchi, Gaurav Choudhary
Abstract
Idiopathic Pulmonary Fibrosis (IPF) is characterized by aberrant repair that diminishes lung function via mechanisms that remain poorly understood. C-C chemokine receptor (CCR10) and its ligand, CCL28, were both elevated in IPF compared with normal donors. CCR10 was highly expressed by various cells from IPF lungs, most notably stage-specific embryonic antigen (SSEA)-4+ mesenchymal progenitor cells (MPCs). In vitro, CCL28 promoted the proliferation of CCR10+ MPCs while CRISPR-Cas9-mediated targeting of CCR10 resulted in the death of MPCs. Following the intravenous injection of various cells from IPF lungs into immunodeficient (NSG) mice, human CCR10+ cells initiated and maintained fibrosis in NSG mice. Eph receptor A3 (EphA3) was among the highest expressed receptor tyrosine kinases detected on IPF CCR10+ cells. Ifabotuzumab-targeted killing of EphA3+ cells significantly reduced the numbers of CCR10+ cells and ameliorated pulmonary fibrosis in humanized NSG mice. Thus, human CCR10+ cells promote pulmonary fibrosis and EphA3 mAb-directed elimination of these cells inhibits lung fibrosis.
Authors
Miriam S. Hohmann, David M. Habiel, Milena S. Espindola, Guanling Huang, Isabelle Jones, Rohan Narayanan, Ana Lucia Coelho, Justin M. Oldham, Imre Noth, Shwu-Fan Ma, Adrianne Kurkciyan, Jonathan L. McQualter, Gianni Carraro, Barry Stripp, Peter Chen, Dianhua Jiang, Paul W. Noble, William Parks, John Woronicz, Geoffrey Yarranton, Lynne A. Murray, Cory M. Hogaboam
Abstract
The epithelial cell-derived cytokines IL-25, IL-33 and TSLP initiate type 2 inflammation in allergic diseases including asthma. However, the signaling pathway regulating these cytokines expression remains elusive. Since microRNAs are pivotal regulators of gene expression, we profiled microRNA expression in bronchial epithelial brushings from type 2-low and type 2-high asthma patients. MiR-206 was the most highly expressed epithelial microRNA in type 2-high asthma relative to type 2-low asthma but was downregulated in both subsets compared with healthy controls. CD39, an ectonucleotidase degrading ATP, was a target of miR-206 and upregulated in asthma. Allergen-induced acute extracellular ATP accumulation led to miR-206 downregulation and CD39 upregulation in human bronchial epithelial cells, forming a feedback loop to eliminate excessive ATP. Airway ATP levels were markedly elevated and strongly correlated with IL-25 and TSLP expression in asthma patients. Intriguingly, airway miR-206 antagonism increased Cd39 expression, reduced ATP accumulation, suppressed Il-25, Il-33, Tslp expression and group 2 innate lymphoid cell expansion, and alleviated type 2 inflammation in a mouse model of allergic airway inflammation. In contrast, airway miR-206 overexpression had opposite effects. Overall, epithelial miR-206 upregulates airway IL-25, TSLP expression by targeting CD39-extracellular ATP axis, which represents a novel therapeutic target in type 2-high asthma.
Authors
Kan Zhang, Yuchen Feng, Yuxia Liang, Wenliang Wu, Chenli Chang, Dian Chen, Shengchong Chen, Jiali Gao, Gongqi Chen, Lingling Yi, Dan Cheng, Guohua Zhen
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