Pulmonology
Abstract
Tissue fibrosis remains unamenable to meaningful therapeutic interventions and is the primary cause of chronic graft failure after organ transplantation. Eukaryotic translation initiation factor (eIF4E), a key translational regulator, serves as convergent target of multiple upstream profibrotic signaling pathways that contribute to mesenchymal cell (MC) activation. Here, we investigate the role of MAP kinase–interacting serine/threonine kinase–induced (MNK-induced) direct phosphorylation of eIF4E at serine 209 (Ser209) in maintaining fibrotic transformation of MCs and determine the contribution of the MNK/eIF4E pathway to the pathogenesis of chronic lung allograft dysfunction (CLAD). MCs from patients with CLAD demonstrated constitutively higher eIF4E phosphorylation at Ser209, and eIF4E phospho-Ser209 was found to be critical in regulating key fibrogenic protein autotaxin, leading to sustained β-catenin activation and profibrotic functions of CLAD MCs. MNK1 signaling was upregulated in CLAD MCs, and genetic or pharmacologic targeting of MNK1 activity inhibited eIF4E phospho-Ser209 and profibrotic functions of CLAD MCs in vitro. Treatment with an MNK1/2 inhibitor (eFT-508) abrogated allograft fibrosis in an orthotopic murine lung-transplant model. Together these studies identify what we believe is a previously unrecognized MNK/eIF4E/ATX/β-catenin signaling pathway of fibrotic transformation of MCs and present the first evidence, to our knowledge, for the utility of MNK inhibitors in fibrosis.
Authors
Natalie M. Walker, Yuta Ibuki, A. Patrick McLinden, Keizo Misumi, Dylan C. Mitchell, Gabriel G. Kleer, Alison M. Lock, Ragini Vittal, Nahum Sonenberg, Amanda L. Garner, Vibha N. Lama
Abstract
Epithelial barriers are programmed for defense and repair but are also the site of long-term structural remodeling and disease. In general, this paradigm features epithelial stem cell (ESCs) that are called on to regenerate damaged tissues but can also be reprogrammed for detrimental remodeling. Here we identified a Wfdc21-dependent monocyte-derived dendritic cell (moDC) population that functioned as an early sentinel niche for basal-ESC reprogramming in mouse models of epithelial injury after respiratory viral infection. Niche function depended on moDC delivery of ligand GPNMB to basal-ESC receptor CD44 so that properly timed antibody blockade of ligand or receptor provided long-lasting correction of reprogramming and broad disease phenotypes. These same control points worked directly in mouse and human basal-ESC organoids. Together, the findings identify a mechanism to explain and modify what is otherwise a stereotyped but sometimes detrimental response to epithelial injury.
Authors
Kangyun Wu, Yong Zhang, Huiqing Yin-DeClue, Kelly Sun, Dailing Mao, Kuangying Yang, Stephen R. Austin, Erika C. Crouch, Steven L. Brody, Derek E. Byers, Christy M. Hoffmann, Michael E. Hughes, Michael J. Holtzman
Abstract
Reciprocal interactions between alveolar fibroblasts and epithelial cells are crucial for lung homeostasis, injury repair, and fibrogenesis, but underlying mechanisms remain unclear. To investigate, we administered the fibroblast-selective TGFβ1 signaling inhibitor, epigallocatechin gallate (EGCG), to Interstitial Lung Disease (ILD) patients undergoing diagnostic lung biopsy and conducted single-cell RNA sequencing on spare tissue. Biopsies from untreated patients showed higher fibroblast TGFβ1 signaling compared to non-disease donor or end-stage ILD tissues. In vivo, EGCG downregulated TGFβ1 signaling and several pro-inflammatory and stress pathways in biopsy samples. Notably, EGCG reduced fibroblast secreted frizzle-like receptor protein 2 (sFRP2), an unrecognized TGFβ1 fibroblast target gene induced near type II alveolar epithelial cells (AEC2s) in situ. Using AEC2-fibroblast coculture organoids and precision cut lung slices (PCLS) from non-diseased donors, we found TGFβ1 signaling promotes a spread AEC2 KRT17+ basaloid state, whereupon sFRP2 then activates a mature Krt5+ basal cell program. Wnt-receptor Frizzled 5 (Fzd5) expression and downstream calcineurin signaling were required for sFRP2-induced nuclear NFATc3 accumulation and KRT5 expression. These findings highlight stage-specific TGFβ1 signaling in ILD, the therapeutic potential of EGCG in reducing IPF-related transcriptional changes, and identify TGFβ1-non-canonical Wnt pathway crosstalk via sFRP2 as a novel mechanism for dysfunctional epithelial signaling in Idiopathic Pulmonary Fibrosis/ILD.
Authors
Max L. Cohen, Alexis N. Brumwell, Tsung Che Ho, Kiana Garakani, Genevieve Montas, Darren Leong, Vivianne W. Ding, Jeffrey A. Golden, Binh N. Trinh, David M. Jablons, Michael A. Matthay, Kirk D. Jones, Paul J. Wolters, Ying Wei, Harold A. Chapman, Claude Jourdan Le Saux
Abstract
Authors
Rick Kapur, John W. Semple, Alexander P.J. Vlaar
Abstract
Authors
Simon J. Cleary, Mark R. Looney
Abstract
Transforming growth factor β (TGF-β) signaling is a core pathway of fibrosis, but the molecular regulation of the activation of latent TGF-β remains incompletely understood. Here, we demonstrate a crucial role of WNT5A/JNK/ROCK signaling that rapidly coordinates the activation of latent TGF-β in fibrotic diseases. WNT5A was identified as a predominant noncanonical WNT ligand in fibrotic diseases such as systemic sclerosis, sclerodermatous chronic graft-versus-host disease, and idiopathic pulmonary fibrosis, stimulating fibroblast-to-myofibroblast transition and tissue fibrosis by activation of latent TGF-β. The activation of latent TGF-β requires rapid JNK- and ROCK-dependent cytoskeletal rearrangements and integrin αV (ITGAV). Conditional ablation of WNT5A or its downstream targets prevented activation of latent TGF-β, rebalanced TGF-β signaling, and ameliorated experimental fibrosis. We thus uncovered what we believe to be a novel mechanism for the aberrant activation of latent TGF-β in fibrotic diseases and provided evidence for targeting WNT5A/JNK/ROCK signaling in fibrotic diseases as a new therapeutic approach.
Authors
Thuong Trinh-Minh, Chih-Wei Chen, Cuong Tran Manh, Yi-Nan Li, Honglin Zhu, Xiang Zhou, Debomita Chakraborty, Yun Zhang, Simon Rauber, Clara Dees, Neng-Yu Lin, Delf Kah, Richard Gerum, Christina Bergmann, Alexander Kreuter, Christiane Reuter, Florian Groeber-Becker, Beate Eckes, Oliver Distler, Ben Fabry, Andreas Ramming, Alexandra Schambony, Georg Schett, Jörg H.W. Distler
Abstract
BACKGROUND. The molecular signature of pediatric acute respiratory distress syndrome (ARDS) is poorly described, and the degree to which hyperinflammation or specific tissue injury contributes to outcomes is unknown. Therefore, we profiled inflammation and tissue injury dynamics over the first 7 days of ARDS, and associated specific biomarkers with mortality, persistent ARDS, and persistent multiple organ dysfunction syndrome (MODS). METHODS. In a single-center prospective cohort of intubated pediatric ARDS, we collected plasma on days 0, 3, and 7. Nineteen biomarkers reflecting inflammation, tissue injury, and damage associated molecular patterns were measured. We assessed the relationship between biomarkers and trajectories with mortality, persistent ARDS, or persistent MODS using multivariable mixed effect models. RESULTS. In 279 subjects (64 [23%] non-survivors), hyperinflammatory cytokines, tissue injury markers, and DAMPs were higher in non-survivors. Survivors and non-survivors showed different biomarker trajectories. IL-1α, sTNFR1, ANG2, and SPD increased in non-survivors, while DAMPs remained persistently elevated. ANG2 and P3NP were associated with persistent ARDS, whereas multiple cytokines, tissue injury markers, and DAMPs were associated with persistent MODS. Corticosteroid use did not impact the association of biomarker levels or trajectory with mortality. CONCLUSIONS. Pediatric ARDS survivors and non-survivors had distinct biomarker trajectories, with cytokines, endothelial and alveolar epithelial injury, and DAMPs elevated in non-survivors. Mortality markers overlapped with markers associated with persistent MODS, rather than persistent ARDS.
Authors
Nadir Yehya, Thomas J. Booth, Gnana D. Ardhanari, Jill M. Thompson, L.K. Metthew Lam, Jacob E. Till, Mark V. Mai, Garrett Keim, Daniel J. McKeone, E. Scott Halstead, Patrick Lahni, Brian M. Varisco, Wanding Zhou, Erica L. Carpenter, Jason D. Christie, Nilam S. Mangalmurti
Abstract
Antibodies can initiate lung injury in a variety of disease states such as autoimmunity, transfusion reactions, or after organ transplantation, but the key factors determining in vivo pathogenicity of injury-inducing antibodies are unclear. Harmful antibodies often activate the complement cascade. A model for how IgG antibodies trigger complement activation involves interactions between IgG Fc domains driving assembly of IgG hexamer structures that activate C1 complexes. The importance of IgG hexamers in initiating injury responses was unclear, so we tested their relevance in a mouse model of alloantibody and complement-mediated acute lung injury. We used three approaches to block alloantibody hexamerization (antibody carbamylation, the K439E Fc mutation, or treatment with domain B from Staphylococcal protein A), all of which reduced acute lung injury. Conversely, Fc mutations promoting spontaneous hexamerization made a harmful alloantibody into a more potent inducer of acute lung injury and rendered an innocuous alloantibody pathogenic. Treatment with a recombinant Fc hexamer ‘decoy’ therapeutic protected mice from lung injury, including in a model with transgenic human FCGR2A expression that exacerbated pathology. These results indicate an in vivo role of IgG hexamerization in initiating acute lung injury and the potential for therapeutics that inhibit or mimic hexamerization to treat antibody-mediated diseases.
Authors
Simon J. Cleary, Yurim Seo, Jennifer J. Tian, Nicholas Kwaan, David P. Bulkley, Arthur E. H. Bentlage, Gestur Vidarsson, Éric Boilard, Rolf Spirig, James C. Zimring, Mark R. Looney
Abstract
Fibrosis following tissue injury is distinguished from normal repair by the accumulation of pathogenic and apoptosis-resistant myofibroblasts (MFs), which arise primarily by differentiation from resident fibroblasts. Endogenous molecular brakes that promote MF dedifferentiation and clearance during spontaneous resolution of experimental lung fibrosis may provide insights that could inform and improve treatment of progressive pulmonary fibrosis in patients. Mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP1) influences cellular phenotype and fate through precise and timely regulation of MAPK activity within various cell types and tissues, yet its role in lung fibroblasts and pulmonary fibrosis has not been explored. Utilizing gain- and loss-of-function studies, we found that MKP1 promoted lung MF dedifferentiation and restored their sensitivity to apoptosis — effects determined to be mainly dependent upon its dephosphorylation of p38α MAPK (p38α). Fibroblast-specific deletion of MKP1 following peak bleomycin-induced lung fibrosis largely abrogated its subsequent spontaneous resolution. Such resolution was restored by treating these transgenic mice with the p38α inhibitor VX-702. We conclude that MKP1 is a critical antifibrotic brake whose inhibition of pathogenic p38α in lung fibroblasts is necessary for fibrosis resolution following lung injury.
Authors
Sean M. Fortier, Natalie M. Walker, Loka R. Penke, Jared D. Baas, Qinxue Shen, Jennifer M. Speth, Steven K. Huang, Rachel L. Zemans, Anton M. Bennett, Marc Peters-Golden
Abstract
Premature birth disrupts normal lung development and places infants at risk for bronchopulmonary dysplasia (BPD), a disease disrupting lung health throughout the life of an individual and that is increasing in incidence. The TGF-β superfamily has been implicated in BPD pathogenesis, however, what cell lineage it impacts remains unclear. We show that TGFbr2 is critical for alveolar epithelial (AT1) cell fate maintenance and function. Loss of TGFbr2 in AT1 cells during late lung development leads to AT1-AT2 cell reprogramming and altered pulmonary architecture, which persists into adulthood. Restriction of fetal lung stretch and associated AT1 cell spreading through a model of oligohydramnios enhances AT1-AT2 reprogramming. Transcriptomic and proteomic analyses reveal the necessity of TGFbr2 expression in AT1 cells for extracellular matrix production. Moreover, TGF-β signaling regulates integrin transcription to alter AT1 cell morphology, which further impacts ECM expression through changes in mechanotransduction. These data reveal the cell intrinsic necessity of TGF-β signaling in maintaining AT1 cell fate and reveal this cell lineage as a major orchestrator of the alveolar matrisome.
Authors
Danielle A. Callaway, Ian J. Penkala, Su Zhou, Jonathan J. Knowlton, Fabian Cardenas-Diaz, Apoorva Babu, Michael P. Morley, Mariana Lopes, Benjamin A. Garcia, Edward E. Morrisey
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)