Vascular endothelial barrier dysfunction underlies diseases such as acute respiratory distress syndrome (ARDS), characterized by edema and inflammatory cell infiltration. The transcription factor HIF2α is highly expressed in vascular endothelial cells (ECs) and may regulate endothelial barrier function. Here, we analyzed promoter sequences of genes encoding proteins that regulate adherens junction (AJ) integrity and determined that
Haixia Gong, Jalees Rehman, Haiyang Tang, Kishore Wary, Manish Mittal, Pallavi Chatturvedi, Youyang Zhao, Yulia A. Komorova, Stephen M. Vogel, Asrar B. Malik
Although aging is a known risk factor for idiopathic pulmonary fibrosis (IPF), the pathogenic mechanisms that underlie the effects of advancing age remain largely unexplained. Some age-related neurodegenerative diseases have an etiology that is related to mitochondrial dysfunction. Here, we found that alveolar type II cells (AECIIs) in the lungs of IPF patients exhibit marked accumulation of dysmorphic and dysfunctional mitochondria. These mitochondrial abnormalities in AECIIs of IPF lungs were associated with upregulation of ER stress markers and were recapitulated in normal mice with advancing age in response to stimulation of ER stress. We found that impaired mitochondria in IPF and aging lungs were associated with low expression of PTEN-induced putative kinase 1 (PINK1). Knockdown of PINK1 expression in lung epithelial cells resulted in mitochondria depolarization and expression of profibrotic factors. Moreover, young PINK1-deficient mice developed similarly dysmorphic, dysfunctional mitochondria in the AECIIs and were vulnerable to apoptosis and development of lung fibrosis. Our data indicate that PINK1 deficiency results in swollen, dysfunctional mitochondria and defective mitophagy, and promotes fibrosis in the aging lung.
Marta Bueno, Yen-Chun Lai, Yair Romero, Judith Brands, Claudette M. St. Croix, Christelle Kamga, Catherine Corey, Jose D. Herazo-Maya, John Sembrat, Janet S. Lee, Steve R. Duncan, Mauricio Rojas, Sruti Shiva, Charleen T. Chu, Ana L. Mora
Mutations in the essential telomerase genes
Susan E. Stanley, Julian J.L. Chen, Joshua D. Podlevsky, Jonathan K. Alder, Nadia N. Hansel, Rasika A. Mathias, Xiaodong Qi, Nicholas M. Rafaels, Robert A. Wise, Edwin K. Silverman, Kathleen C. Barnes, Mary Armanios
Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disorder with no effective medical treatments available. The generation of myofibroblasts, which are critical for fibrogenesis, requires both a mechanical signal and activated TGF-β; however, it is not clear how fibroblasts sense and transmit the mechanical signal(s) that promote differentiation into myofibroblasts. As transient receptor potential vanilloid 4 (TRPV4) channels are activated in response to changes in plasma membrane stretch/matrix stiffness, we investigated whether TRPV4 contributes to generation of myofibroblasts and/or experimental lung fibrosis. We determined that TRPV4 activity is upregulated in lung fibroblasts derived from patients with IPF. Moreover, TRPV4-deficient mice were protected from fibrosis. Furthermore, genetic ablation or pharmacological inhibition of TRPV4 function abrogated myofibroblast differentiation, which was restored by TRPV4 reintroduction. TRPV4 channel activity was elevated when cells were plated on matrices of increasing stiffness or on fibrotic lung tissue, and matrix stiffness–dependent myofibroblast differentiation was reduced in response to TRVP4 inhibition. TRPV4 activity modulated TGF-β1–dependent actions in a SMAD-independent manner, enhanced actomyosin remodeling, and increased nuclear translocation of the α-SMA transcription coactivator (MRTF-A). Together, these data indicate that TRPV4 activity mediates pulmonary fibrogenesis and suggest that manipulation of TRPV4 channel activity has potential as a therapeutic approach for fibrotic diseases.
Shaik O. Rahaman, Lisa M. Grove, Sailaja Paruchuri, Brian D. Southern, Susamma Abraham, Kathryn A. Niese, Rachel G. Scheraga, Sudakshina Ghosh, Charles K. Thodeti, David X. Zhang, Magdalene M. Moran, William P. Schilling, Daniel J. Tschumperlin, Mitchell A. Olman
The intracellular scaffold protein IQGAP1 supports protein complexes in conjunction with numerous binding partners involved in multiple cellular processes. Here, we determined that IQGAP1 modulates airway smooth muscle contractility. Compared with WT controls, at baseline as well as after immune sensitization and challenge,
Mallar Bhattacharya, Aparna Sundaram, Makoto Kudo, Jessica Farmer, Previn Ganesan, Amin Khalifeh-Soltani, Mehrdad Arjomandi, Kamran Atabai, Xiaozhu Huang, Dean Sheppard
The pathogenesis of chronic obstructive pulmonary disease (COPD) remains unclear, but involves loss of alveolar surface area (emphysema) and airway inflammation (bronchitis) as the consequence of cigarette smoke (CS) exposure. Previously, we demonstrated that autophagy proteins promote lung epithelial cell death, airway dysfunction, and emphysema in response to CS; however, the underlying mechanisms have yet to be elucidated. Here, using cultured pulmonary epithelial cells and murine models, we demonstrated that CS causes mitochondrial dysfunction that is associated with a reduction of mitochondrial membrane potential. CS induced mitophagy, the autophagy-dependent elimination of mitochondria, through stabilization of the mitophagy regulator PINK1. CS caused cell death, which was reduced by administration of necrosis or necroptosis inhibitors. Genetic deficiency of PINK1 and the mitochondrial division/mitophagy inhibitor Mdivi-1 protected against CS-induced cell death and mitochondrial dysfunction in vitro and reduced the phosphorylation of MLKL, a substrate for RIP3 in the necroptosis pathway. Moreover,
Kenji Mizumura, Suzanne M. Cloonan, Kiichi Nakahira, Abhiram R. Bhashyam, Morgan Cervo, Tohru Kitada, Kimberly Glass, Caroline A. Owen, Ashfaq Mahmood, George R. Washko, Shu Hashimoto, Stefan W. Ryter, Augustine M. K. Choi
Development of the vascular disease pulmonary hypertension (PH) involves disparate molecular pathways that span multiple cell types. MicroRNAs (miRNAs) may coordinately regulate PH progression, but the integrative functions of miRNAs in this process have been challenging to define with conventional approaches. Here, analysis of the molecular network architecture specific to PH predicted that the miR-130/301 family is a master regulator of cellular proliferation in PH via regulation of subordinate miRNA pathways with unexpected connections to one another. In validation of this model, diseased pulmonary vessels and plasma from mammalian models and human PH subjects exhibited upregulation of miR-130/301 expression. Evaluation of pulmonary arterial endothelial cells and smooth muscle cells revealed that miR-130/301 targeted PPARγ with distinct consequences. In endothelial cells, miR-130/301 modulated apelin-miR-424/503-FGF2 signaling, while in smooth muscle cells, miR-130/301 modulated STAT3-miR-204 signaling to promote PH-associated phenotypes. In murine models, induction of miR-130/301 promoted pathogenic PH-associated effects, while miR-103/301 inhibition prevented PH pathogenesis. Together, these results provide insight into the systems-level regulation of miRNA-disease gene networks in PH with broad implications for miRNA-based therapeutics in this disease. Furthermore, these findings provide critical validation for the evolving application of network theory to the discovery of the miRNA-based origins of PH and other diseases.
Thomas Bertero, Yu Lu, Sofia Annis, Andrew Hale, Balkrishen Bhat, Rajan Saggar, Rajeev Saggar, W. Dean Wallace, David J. Ross, Sara O. Vargas, Brian B. Graham, Rahul Kumar, Stephen M. Black, Sohrab Fratz, Jeffrey R. Fineman, James D. West, Kathleen J. Haley, Aaron B. Waxman, B. Nelson Chau, Katherine A. Cottrill, Stephen Y. Chan
The pathogenesis of mucoinfective lung disease in cystic fibrosis (CF) patients likely involves poor mucus clearance. A recent model of mucus clearance predicts that mucus flow depends on the relative mucin concentration of the mucus layer compared with that of the periciliary layer; however, mucin concentrations have been difficult to measure in CF secretions. Here, we have shown that the concentration of mucin in CF sputum is low when measured by immunologically based techniques, and mass spectrometric analyses of CF mucins revealed mucin cleavage at antibody recognition sites. Using physical size exclusion chromatography/differential refractometry (SEC/dRI) techniques, we determined that mucin concentrations in CF secretions were higher than those in normal secretions. Measurements of partial osmotic pressures revealed that the partial osmotic pressure of CF sputum and the retained mucus in excised CF lungs were substantially greater than the partial osmotic pressure of normal secretions. Our data reveal that mucin concentration cannot be accurately measured immunologically in proteolytically active CF secretions; mucins are hyperconcentrated in CF secretions; and CF secretion osmotic pressures predict mucus layer–dependent osmotic compression of the periciliary liquid layer in CF lungs. Consequently, mucin hypersecretion likely produces mucus stasis, which contributes to key infectious and inflammatory components of CF lung disease.
Ashley G. Henderson, Camille Ehre, Brian Button, Lubna H. Abdullah, Li-Heng Cai, Margaret W. Leigh, Genevieve C. DeMaria, Hiro Matsui, Scott H. Donaldson, C. William Davis, John K. Sheehan, Richard C. Boucher, Mehmet Kesimer
Pathological remodeling of the extracellular matrix (ECM) by fibroblasts leads to organ failure. Development of idiopathic pulmonary fibrosis (IPF) is characterized by a progressive fibrotic scarring in the lung that ultimately leads to asphyxiation; however, the cascade of events that promote IPF are not well defined. Here, we examined how the interplay between the ECM and fibroblasts affects both the transcriptome and translatome by culturing primary fibroblasts generated from IPF patient lung tissue or nonfibrotic lung tissue on decellularized lung ECM from either IPF or control patients. Surprisingly, the origin of the ECM had a greater impact on gene expression than did cell origin, and differences in translational control were more prominent than alterations in transcriptional regulation. Strikingly, genes that were translationally activated by IPF-derived ECM were enriched for those encoding ECM proteins detected in IPF tissue. We determined that genes encoding IPF-associated ECM proteins are targets for miR-29, which was downregulated in fibroblasts grown on IPF-derived ECM, and baseline expression of ECM targets could be restored by overexpression of miR-29. Our data support a model in which fibroblasts are activated to pathologically remodel the ECM in IPF via a positive feedback loop between fibroblasts and aberrant ECM. Interrupting this loop may be a strategy for IPF treatment.
Matthew W. Parker, Daniel Rossi, Mark Peterson, Karen Smith, Kristina Sikström, Eric S White, John E. Connett, Craig A. Henke, Ola Larsson, Peter B. Bitterman
The development of emphysema in humans and mice exposed to cigarette smoke is promoted by activation of an adaptive immune response. Lung myeloid dendritic cells (mDCs) derived from cigarette smokers activate autoreactive Th1 and Th17 cells. mDC-dependent activation of T cell subsets requires expression of the
Ming Shan, Ran You, Xiaoyi Yuan, Michael V. Frazier, Paul Porter, Alexander Seryshev, Jeong-Soo Hong, Li-zhen Song, Yiqun Zhang, Susan Hilsenbeck, Lawrence Whitehead, Nazanin Zarinkamar, Sarah Perusich, David B. Corry, Farrah Kheradmand