Research
Abstract
An intact lung epithelial barrier is essential for lung homeostasis. The Na+, K+-ATPase (NKA), primarily serving as an ion transporter, also regulates epithelial barrier function via modulation of tight junctions. However, the underlying mechanism is not well-understood. Here, we showed that overexpression of the NKA β1 subunit upregulates the expression of tight junction proteins, leading to increased alveolar epithelial barrier function by an ion transport-independent mechanism. Using immunoprecipitation and mass spectrometry, we identified a number of unknown protein interactions of the β1 subunit, including a top candidate, myotonic dystrophy kinase-related cdc42-binding kinase α (MRCKα), a protein kinase known to regulate peripheral actin formation. Using a doxycycline-inducible gene expression system, we demonstrated that MRCKα and its downstream activation of myosin light chain is required for the regulation of alveolar barrier function by the NKA β1 subunit. Importantly, MRCKα is expressed in both human airways and alveoli and has reduced expression in patients with Acute Respiratory Distress Syndrome (ARDS), a lung illness that can be caused by multiple direct and indirect insults, including the infection of influenza virus and SARS-CoV-2. Our results have elucidated a novel mechanism by which NKA regulates epithelial tight junctions and identified potential drug targets for treating ARDS and other pulmonary diseases that are caused by barrier dysfunction.
Authors
Haiqing Bai, Rui Zhou, Michael Barravecchia, Rosemary Norman, Alan E. Friedman, Deborah Yu, Xin Lin, Jennifer L. Young, David A. Dean
Abstract
Preterm birth increases the risk for pulmonary hypertension and heart failure in adulthood. Oxygen therapy can damage the immature cardiopulmonary system and may be partially responsible for the cardiovascular disease in adults born preterm. We previously showed that exposing newborn mice to hyperoxia causes pulmonary hypertension by 1 year of age that is preceded by a poorly understood loss of pulmonary vein cardiomyocyte proliferation. We now show that hyperoxia also reduces cardiomyocyte proliferation and survival in the left atrium and causes diastolic heart failure by disrupting its filling of the left ventricle. Transcriptomic profiling showed that neonatal hyperoxia permanently suppressed fatty acid synthase (Fasn), stearoyl-CoA desaturase 1 (Scd1) and other fatty acid synthesis genes in the atria of mice, the HL-1 line of mouse atrial cardiomyocytes and left atrial tissue explanted from human infants. Suppressing Fasn or Scd1 reduced HL-1 cell proliferation and increased cell death while overexpressing these genes maintained their expansion in hyperoxia, suggesting oxygen directly inhibits atrial cardiomyocyte proliferation and survival by repressing Fasn and Scd1. Pharmacologic interventions that restore Fasn, Scd1 and other fatty acid synthesis genes in atrial cardiomyocytes may thus provide a way of ameliorating the adverse effects of supplemental oxygen on preterm infants.
Authors
Ethan David Cohen, Min Yee, George A. Porter, Jr., Erin E. Ritzer, Andrew N. McDavid, Paul S. Brookes, Gloria S. Pryhuber, Michael A. O'Reilly
Abstract
Abdominal aortic aneurysm (AAA) is a life-threatening degenerative vascular disease. Endothelial cell (EC) dysfunction is implicated in AAA. Our group recently demonstrated that Krüppel-like factor 11 (KLF11) plays an essential role in maintaining vascular homeostasis, at least partially through inhibition of EC inflammatory activation. However, the functions of endothelial KLF11 in AAA remain unknown. Here we found that endothelial KLF11 expression was reduced in the ECs from human aneurysms and was time-dependently decreased in the aneurysmal endothelium from both elastase- and Pcsk9/AngII-induced AAA mouse models. KLF11 deficiency in ECs markedly aggravated AAA formation, whereas EC-selective KLF11 overexpression significantly inhibited AAA formation. Mechanistically, KLF11 not only inhibited the EC inflammatory response but also diminished MMP9 expression and activity and reduced NADPH oxidase 2-mediated production of reactive oxygen species in ECs. In addition, KLF11-deficient ECs induce smooth muscle cell dedifferentiation and apoptosis. Overall, we established endothelial KLF11 as a novel factor protecting against AAA and a potential target for intervention in aortic aneurysms.
Authors
Guizhen Zhao, Ziyi Chang, Yang Zhao, Yanhong Guo, Haocheng Lu, Wenying Liang, Oren Rom, Huilun Wang, Jinjian Sun, Tianqing Zhu, Yanbo Fan, Lin Chang, Bo Yang, Minerva Garcia-Barrio, Eugene Chen, Jifeng Zhang
Abstract
Myotonic dystrophy type 1 (DM1) is caused by a CTG-repeat expansion in the DMPK gene. Expression of pathogenic expanded CUG-repeat (CUGexp) RNA causes multisystemic disease by perturbing the functions of RNA binding proteins, resulting in expression of fetal protein isoforms in adult tissues. Cardiac involvement affects 50% of individuals with DM1 and causes 25% of disease-related deaths. We developed a transgenic mouse model for tetracycline-inducible and heart-specific expression of human DMPK mRNA containing 960 CUG repeats. CUGexp RNA is expressed in atria and ventricles and induced mice exhibit electrophysiological and molecular features of DM1 disease including cardiac conduction delays, supraventricular arrhythmias, nuclear RNA foci with Muscleblind protein colocalization and alternative splicing defects. Importantly, these phenotypes were rescued upon loss of CUGexp RNA expression. Transcriptome analysis revealed gene expression and alternative splicing changes in ion transport genes that are associated with inherited cardiac conduction diseases, including a subset of genes involved in calcium handling. Consistent with RNA-seq results, calcium handling defects were identified in atrial cardiomyocytes isolated from mice expressing CUGexp RNA. These results identify potential tissue-specific mechanisms contributing to cardiac pathogenesis in DM1 and demonstrate the utility of reversible phenotypes in our model to facilitate development of targeted therapeutic approaches.
Authors
Ashish N. Rao, Hannah M. Campbell, Xiangnan Guan, Tarah A. Word, Xander H.T. Wehrens, Zheng Xia, Thomas A. Cooper
Abstract
Limitations of checkpoint inhibitor cancer immunotherapy include induction of autoimmune syndromes and resistance of many cancers. Since CD318, a novel CD6 ligand, is associated with aggressiveness and metastatic potential of human cancers, we tested the effect of an anti-CD6 monoclonal antibody, UMCD6, on killing of cancer cells by human lymphocytes. UMCD6 augmented killing of breast, lung or prostate cancer cells through direct effects on both CD8+ T cells and natural killer (NK) cells, increasing cancer cell death and lowering cancer cell survival in vitro more robustly than monoclonal antibody checkpoint inhibitors that interrupt the PD-1/PD-L1 axis. UMCD6 also augmented in vivo killing by human peripheral blood lymphocytes of a human breast cancer line xeno-transplanted into immunodeficient mice. Mechanistically, UMCD6 upregulated the expression of the activating receptor NKG2D and down-regulated expression of the inhibitory receptor NKG2A on both NK cells and CD8+ T cells, with concurrent increases in perforin and granzyme-B production. The combined capabilities of an anti-CD6 monoclonal antibody to control autoimmunity through effects on CD4+ lymphocyte differentiation, while enhancing killing of cancer cells through distinct effects on CD8+ and NK cells, opens a potential new approach to cancer immunotherapy that would suppress rather than instigate autoimmunity.
Authors
Jeffrey H. Ruth, Mikel Gurrea-Rubio, Kalana S. Athukorala, Stephanie M. Rasmussen, Daniel Weber, Peggy M. Randon, Rosemary J. Gedert, Matthew E. Lind, Mohammad Asif Amin, Phillip L. Campbell, Pei-Suen Tsou, Yang Mao-Draayer, Qi Wu, Thomas M. Lanigan, Venkateshwar G. Keshamouni, Nora G. Singer, Feng Lin, David A Fox
Abstract
Cancer is caused primarily by genomic alterations resulting in deregulation of gene regulatory circuits in key growth, apoptosis or DNA repair pathways. Multiple genes associated with the initiation and development of tumors are also regulated at the level of mRNA decay, through the recruitment of RNA binding proteins to AU-rich elements (AREs) located in their 3’-untranslated regions. One of these ARE-binding proteins, tristetraprolin (TTP, encoded by Zfp36) is consistently dysregulated in many human malignancies. Herein, using regulated overexpression or conditional ablation in the context of chemical cutaneous carcinogenesis, we show that TTP represents a critical regulator of skin tumorigenesis. We provide evidence that TTP controls both tumor-associated inflammation and key oncogenic pathways in neoplastic epidermal cells. We identify Areg as a direct target of TTP in keratinocytes, and show that EGFR signaling potentially contributes to exacerbated tumor formation. Finally, single-cell RNA-Sequencing analysis indicates that ZFP36 is downregulated in human malignant keratinocytes. We conclude that TTP expression by epidermal cells plays a major role in the control of skin tumorigenesis.
Authors
Assiya Assabban, Ingrid Dubois-Vedrenne, Laurye Van Maele, Rosalba Salcedo, Brittany L. Snyder, Lecong Zhou, Abdulkader Azouz, Bérengère de Toeuf, Gaëlle Lapouge, Caroline La, Maxime Melchior, Muriel Nguyen, Séverine Thomas, Si Fan Wu, Wenqian Hu, Véronique Kruys, Cédric Blanpain, Giorgio Trinchieri, Cyril Gueydan, Perry J. Blackshear, Stanislas Goriely
Abstract
Dysmorphic pulmonary vascular growth and abnormal endothelial cell (EC) proliferation are paradoxically observed in premature infants with bronchopulmonary dysplasia (BPD) despite vascular pruning. The pentose phosphate pathway (PPP), a metabolic pathway parallel to glycolysis, generates NADPH as a reducing equivalent and ribose 5-phosphate for nucleotide synthesis. It is unknown whether hyperoxia, a known mediator of BPD in rodent models, alters glycolysis and the PPP in lung ECs. We hypothesized that hyperoxia increases glycolysis and the PPP, resulting in abnormal EC proliferation and dysmorphic angiogenesis in neonatal mice. To test this hypothesis, lung ECs and newborn mice were exposed to hyperoxia and allowed to recover in air. Hyperoxia increased glycolysis and the PPP. Increased PPP, but not glycolysis, caused hyperoxia-induced abnormal EC proliferation. Blocking the PPP reduced hyperoxia-induced glucose-derived deoxynucleotide synthesis in cultured ECs. In neonatal mice, hyperoxia-induced abnormal EC proliferation, dysmorphic angiogenesis, and alveolar simplification were augmented by nanoparticle-mediated endothelial overexpression of phosphogluconate dehydrogenase, the second enzyme in the PPP. These effects were attenuated by inhibitors of the PPP. Altogether, neonatal hyperoxia augments the PPP, causing abnormal lung EC proliferation, dysmorphic vascular development, and alveolar simplification. These novel observations provide mechanisms and potential metabolic targets to prevent BPD-associated vascular dysgenesis.
Authors
Jiannan Gong, Zihang Feng, Abigail L. Peterson, Jennifer F. Carr, Xuexin Lu, Haifeng Zhao, Xiangming Ji, You-Yang Zhao, Monique E. De Paepe, Phyllis A. Dennery, Hongwei Yao
Abstract
Influenza virus infections affect millions of people annually. Current available vaccines provide varying rates of protection. There is a knowledge gap on how the nasal microbiota, particularly established pneumococcal colonization, shapes the response to influenza vaccination. In this study, we inoculated healthy adults with live S. pneumoniae and vaccinated them three days later with either TIV or LAIV. Vaccine-induced immune responses were assessed in nose, blood and lung. Nasal pneumococcal colonization had no impact upon TIV-induced antibody responses to influenza, which manifested in all compartments. However, experimentally-induced pneumococcal colonization dampened LAIV-mediated mucosal antibody responses, primarily IgA in the nose and IgG in the lung. Pulmonary influenza-specific cellular responses were more apparent in the LAIV group compared to either TIV or an unvaccinated group. These results indicate that TIV and LAIV elicit differential immunity to adults and that LAIV immunogenicity is diminished by the nasal presence of S. pneumoniae. Therefore, nasopharyngeal pneumococcal colonization may affect LAIV efficacy.
Authors
Beatriz F. Carniel, Fernando Marcon, Jamie Rylance, Esther L. German, Seher Zaidi, Jesus Reine, Edessa Negera, Elissavet Nikolaou, Sherin Pojar, Carla Solórzano, Andrea M. Collins, Victoria Connor, Debby Bogaert, Stephen B. Gordon, Helder I. Nakaya, Daniela M. Ferreira, Simon P. Jochems, Elena Mitsi
Abstract
Four endemic human coronaviruses (HCoVs) are commonly associated with acute respiratory infection in humans. B cell responses to these “common cold” viruses remain incompletely understood. Here we report a comprehensive analysis of CoV-specific antibody repertoires in 231 children and 1168 adults using phage-immunoprecipitation sequencing. Seroprevalence of antibodies to endemic HCoVs ranged between ~4 and 27% depending on the species and cohort. We identified at least 136 novel linear B cell epitopes. Antibody repertoires against endemic HCoVs were qualitatively different between children and adults in that anti-HCoV IgG specificities more frequently found among children targeted functionally important and structurally conserved regions of the spike, nucleocapsid and matrix proteins. Moreover, antibody specificities targeting the highly conserved fusion peptide region and S2’ cleavage site of the spike protein were broadly cross-reactive with peptides of epidemic human and non-human coronaviruses. In contrast, an acidic tandem repeat in the N-terminal region of the Nsp3 subdomain of the HCoV-HKU1 polyprotein was the predominant target of antibody responses in adult donors. Our findings shed light on the dominant species-specific and pan-CoV target sites of human antibody responses to coronavirus infection, thereby providing important insights for the development of prophylactic or therapeutic monoclonal antibodies and vaccine design.
Authors
Taushif Khan, Mahbuba Rahman, Fatima Al Ali, Susie S.Y. Huang, Manar Ata, Qian Zhang, Paul Bastard, Zhiyong Liu, Emmanuelle Jouanguy, Vivien Beziat, Aurélie Cobat, Gheyath K. Nasrallah, Hadi M. Yassine, Maria K. Smatti, Amira Saeed, Isabelle Vandernoot, Jean-Christophe Goffard, Guillaume Smits, Isabelle Migeotte, Filomeen Haerynck, Isabelle Meyts, Laurent Abel, Jean-Laurent Casanova, Mohammad R. Hasan, Nico Marr
Abstract
Agonistic anti-CD40 monoclonal antibody (mAb) therapy in combination with chemotherapy (chemoimmunotherapy) shows promise for the treatment of pancreatic ductal adenocarcinoma (PDA). To gain insight into immunological mechanisms of response and resistance to chemoimmunotherapy, we analyzed blood samples from patients (n=22) with advanced PDA treated with an anti-CD40 mAb (CP-870,893) in combination with gemcitabine. We found a stereotyped cellular response to chemoimmunotherapy characterized by transient B cell, CD56+CD11c+HLA-DR+CD141+ cell and monocyte depletion and CD4+ T cell activation. However, these cellular pharmacodynamics did not associate with outcomes. In contrast, we identified an inflammatory network in the peripheral blood consisting of neutrophils, cytokines (IL-6 and IL-8) and acute phase reactants (CRP and SAA) that was associated with outcomes. Furthermore, monocytes from patients with elevated plasma IL-6 and IL-8 showed distinct transcriptional profiles, including upregulation of CCR2 and GAS6; genes associated with regulation of leukocyte chemotaxis and response to inflammation. Patients with systemic inflammation, defined by neutrophil-lymphocyte ratio (NLR) >3.1, had a shorter median OS (5.8 vs 12.3mo; p=0.0105) as compared to patients with NLR <3.1. Taken together, our findings identify systemic inflammation as a potential resistance mechanism to a CD40-based chemoimmunotherapy and suggest biomarkers for future studies.
Authors
Max M. Wattenberg, Veronica M. Herrera, Michael A. Giannone, Whitney L. Gladney, Erica L. Carpenter, Gregory L. Beatty
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