Pulmonology
Abstract
Red blood cells (RBCs), traditionally recognized for their role in transporting oxygen, play a pivotal role in the body's immune response by expressing TLR9 and scavenging excess host cell-free DNA. DNA capture by RBCs leads to accelerated RBC clearance and triggers inflammation. Whether RBCs can also acquire microbial DNA during infections is unknown. Murine RBCs acquire microbial DNA in vitro and bacterial-DNA-induced macrophage activation was augmented by WT but not Tlr9-deleted RBCs. In a mouse model of polymicrobial sepsis, RBC-bound bacterial DNA was elevated in WT but not in erythroid Tlr9-deleted mice. Plasma cytokine analysis in these mice revealed distinct sepsis clusters characterized by persistent hypothermia and hyperinflammation in the most severely affected subjects. RBC-Tlr9 deletion attenuated plasma and tissue IL-6 production in the most severe group. Parallel findings in human subjects confirmed that RBCs from septic patients harbored more bacterial DNA compared to healthy individuals. Further analysis through 16S sequencing of RBC-bound DNA illustrated distinct microbial communities, with RBC-bound DNA composition correlating with plasma IL-6 in patients with sepsis. Collectively, these findings unveil RBCs as overlooked reservoirs and couriers of microbial DNA, capable of influencing host inflammatory responses in sepsis.
Authors
LK Metthew Lam, Nathan J. Klingensmith, Layal Sayegh, Emily Oatman, Joshua S. Jose, Christopher V. Cosgriff, Kaitlyn A. Eckart, John McGinnis, Piyush Ranjan, Matthew Lanza, Nadir Yehya, Nuala J. Meyer, Robert P. Dickson, Nilam S. Mangalmurti
Abstract
Females have an increased prevalence of many Th17 cell-mediated diseases, including asthma. Androgen signaling decreases Th17 cell-mediated airway inflammation, and Th17 cells rely on glutaminolysis. However, it remains unclear whether androgen receptor (AR) signaling modifies glutamine metabolism to suppress Th17 cell-mediated airway inflammation. We show that Th17 cells from male humans and mice had decreased glutaminolysis compared to females, and that AR signaling attenuated Th17 cell mitochondrial respiration and glutaminolysis in mice. Using allergen-induced airway inflammation mouse models, we determined females had a selective reliance upon glutaminolysis for Th17-mediated airway inflammation, and AR signaling attenuated glutamine uptake in CD4+ T cells by reducing expression of glutamine transporters. Minimal reliance on glutamine uptake in male Th17 cells compared to female Th17 cells was also found in circulating T cells from patients with asthma. AR signaling thus attenuates glutaminolysis, demonstrating sex-specific metabolic regulation of Th17 cells with implications for Th17 or glutaminolysis targeted therapeutics.
Authors
Nowrin U. Chowdhury, Jacqueline-Yvonne Cephus, Emely Henriquez Pilier, Melissa M. Wolf, Matthew Z. Madden, Shelby N. Kuehnle, Kaitlin E. McKernan, Erin Q. Jennings, Emily N. Arner, Darren R. Heintzman, Channing Chi, Ayaka Sugiura, Matthew T. Stier, Kelsey Voss, Xiang Ye, Kennedi L. Scales, Evan S. Krystofiak, Vivek D. Gandhi, Robert D. Guzy, Katherine N. Cahill, Anne I. Sperling, R. Stokes Peebles Jr., Jeffrey C. Rathmell, Dawn C. Newcomb
Abstract
The most common mutation in surfactant protein C gene (SFTPC), SFTPCI73T, causes interstitial lung disease with few therapeutic options. We previously demonstrated that EMC3, an important component of the multiprotein endoplasmic reticulum membrane complex (EMC), is required for surfactant homeostasis in alveolar type 2 epithelial (AT2) cells at birth. In the present study, we investigated the role of EMC3 in the control of SFTPCI73T metabolism and its associated alveolar dysfunction. Using a knock-in mouse model phenocopying the I73T mutation, we demonstrated that conditional deletion of Emc3 in AT2 cells rescued alveolar remodeling/simplification defects in neonatal and adult mice. Proteomic analysis revealed that Emc3 depletion reversed the disruption of vesicle trafficking pathways and rescued the mitochondrial dysfunction associated with I73T mutation. Affinity purification-mass spectrometry analysis identified potential EMC3 interacting proteins in lung AT2 cells, including Valosin Containing Protein (VCP) and its interactors. Treatment of SftpcI73T knock-in mice and SFTPCI73T expressing iAT2 cells derived from SFTPCI73T patient-specific iPSCs with the specific VCP inhibitor CB5083 restored alveolar structure and SFTPCI73T trafficking respectively. Taken together, the present work identifies the EMC complex and VCP in the metabolism of the disease-associated SFTPCI73T mutant, providing novel therapeutical targets for SFTPCI73T-associated interstitial lung disease.
Authors
Xiaofang Tang, Wei Wei, Yuqing Sun, Timothy E. Weaver, Ernesto S. Nakayasu, Geremy Clair, John M. Snowball, Cheng-Lun Na, Karen S. Apsley, Emily P. Martin, Darrell N. Kotton, Konstantinos-Dionysios Alysandratos, Jiuzhou Huo, Jeffery D. Molkentin, William A. Gower, Xinhua Lin, Jeffrey A. Whitsett
Abstract
The acute respiratory distress syndrome (ARDS) is associated with significant morbidity and mortality and neutrophils are critical to its pathogenesis. Neutrophil activation is closely regulated by inhibitory tyrosine phosphatases including Src homology region 2 domain containing phosphatase-1 (Shp1). Here, we report that loss of neutrophil Shp1 in mice produced hyperinflammation and lethal pulmonary hemorrhage in sterile inflammation and pathogen-induced models of acute lung injury (ALI) through a Syk kinase-dependent mechanism. We observed large intravascular neutrophil clusters, perivascular inflammation, and excessive neutrophil extracellular traps in neutrophil-specific Shp1 knockout mice suggesting an underlying mechanism for the observed pulmonary hemorrhage. Targeted immunomodulation through the administration of a Shp1 activator (SC43) reduced agonist-induced reactive oxygen species in vitro and ameliorated ALI-induced alveolar neutrophilia and NETs in vivo. We propose that the pharmacologic activation of Shp1 has the potential to fine-tune neutrophil hyperinflammation that is central to the pathogenesis of ARDS.
Authors
S. Farshid Moussavi-Harami, Simon J. Cleary, Mélia Magnen, Yurim Seo, Catharina Conrad, Bevin C. English, Longhui Qiu, Kristin M. Wang, Clare L. Abram, Clifford A. Lowell, Mark R. Looney
Abstract
Severe viral pneumonia can induce rapid expansion of KRT5+ basal-like cells in small airways and alveoli; this forms a scar-like structure that persists in the injured alveoli and impedes normal alveolar epithelium regeneration. In this study, we investigated the mechanism by which viral infection induced this remodeling response. Through comparing different lung-injury models, we demonstrated that infection induced strong IFN-γ signal–stimulated dysplastic KRT5+ cell formation. Inactivation of interferon receptor 1 (Ifngr1) reduced dysplastic cell formation, ameliorated lung fibrosis, and improved lung-function recovery. Mechanistically, IFN-γ regulated dysplastic cell formation via the focal adhesion kinase (FAK)/Yes-associated protein 1 (YAP) pathway. Inhibiting FAK/Src diminished IFN-γ–induced YAP nuclear translocation and dysplastic cell formation. Inhibiting YAP during viral infection prevented dysplastic cell formation, whereas inhibiting YAP in persistent KRT5+ cells led to their conversion into distal club cells. Importantly, human dysplastic cells exhibited elevated FAK and YAP activity, and IFN-γ treatment promoted the transformation of human alveolar progenitor cells into dysplastic cells. These findings uncover the role of infection-induced inflammatory response in alveolar remodeling and may provide potential therapeutic avenues for the treatment of alveolar remodeling in patients with severe viral pneumonia.
Authors
Xiuyu Lin, Weicheng Chen, Guilin Yang, Jiazhu Zhang, Huilin Wang, Zeyu Liu, Ying Xi, Tao Ren, Bo Liu, Pengfei Sui
Abstract
The airway surface liquid (ASL) plays a crucial role in lung defense mechanisms, and its composition and volume are regulated by the airway epithelium. The cystic fibrosis transmembrane conductance regulator (CFTR) is abundantly expressed in a rare airway epithelial cell type called an ionocyte. Recently, we demonstrated that ionocytes can increase liquid absorption through apical CFTR and basolateral barttin/chloride channels, while airway secretory cells mediate liquid secretion through apical CFTR channels and basolateral NKCC1 transporters. Th2-driven (IL-4/IL-13) airway diseases, such as asthma, cause goblet cell metaplasia, accompanied by increased mucus production and airway secretions. In this study, we investigate the effect of IL-13 on chloride and liquid transport performed by ionocytes. IL-13 treatment of human airway epithelia was associated with reduced epithelial liquid absorption rates and increased ASL volume. Additionally, IL-13 treatment reduced the abundance of CFTR-positive ionocytes and increased the abundance of CFTR-positive secretory cells. Increasing ionocyte abundance attenuated liquid secretion caused by IL-13. Finally, CFTR-positive ionocytes were less common in asthma and COPD and associated with airflow obstruction. Our findings suggest that loss of CFTR in ionocytes contributes to the liquid secretion observed in IL-13-mediated airway diseases.
Authors
Guillermo S. Romano Ibarra, Lei Lei, Wenjie Yu, Andrew L. Thurman, Nicholas D. Gansemer, David K. Meyerholz, Alejandro A. Pezzulo, Paul B. McCray, Ian M. Thornell, David A. Stoltz
Abstract
A leading cause of mortality after influenza infection is the development of a secondary bacterial pneumonia. In the absence of a bacterial superinfection, prescribing antibacterial therapies is not indicated but has become a common clinical practice for those presenting with a respiratory viral illness. In a murine model, we found that antibiotic use during influenza infection impaired the lung innate immunologic defenses toward a secondary challenge with methicillin-resistant Staphylococcus aureus (MRSA). Antibiotics augment lung eosinophils, which have inhibitory effects on macrophage function through the release of major basic protein. Moreover, we demonstrated antibiotic treatment during influenza infection causes a fungal dysbiosis that drive lung eosinophilia and impair MRSA clearance. Finally, we evaluated three cohorts of hospitalized patients and found eosinophils positively correlated with antibiotic use, systemic inflammation, and worsened outcomes. Altogether, our work demonstrates a detrimental effect of antibiotic treatment during influenza infection that has harmful immunologic consequences via recruitment of eosinophils to the lungs thereby increasing the risk of developing a secondary bacterial infection.
Authors
Marilia Sanches Santos Rizzo Zuttion, Tanyalak Parimon, Stephanie A. Bora, Changfu Yao, Katherine Lagree, Catherine A. Gao, Richard G. Wunderink, Georgios D. Kitsios, Alison Morris, Yingze Zhang, Bryan J. McVerry, Matthew E. Modes, Alberto M. Marchevsky, Barry R. Stripp, Christopher M. Soto, Ying Wang, Kimberly Merene, Silvia Cho, Blandine L. Victor, Ivan Vujkovic-Cvijin, Suman Gupta, Suzanne Cassel, Fayyaz S. Sutterwala, Suzanne Devkota, David M. Underhill, Peter Chen
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
Copyright © 2024 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)