Cell biology
Abstract
COPD is a chronic respiratory disease characterized by small airway remodeling and alveolar emphysema due to environmental stresses such as cigarette smoking (CS). Oxidative stress is commonly implicated in COPD pathology, but recent findings suggest that one oxidant-producing NADPH oxidase homolog, dual oxidase 1 (DUOX1), is downregulated in the airways of COPD patients. We evaluated lung tissue sections from COPD patients for small airway epithelial DUOX1 protein expression, in association with measures of lung function and small airway and alveolar remodeling. We also addressed the impact of DUOX1 for lung tissue remodeling in mouse models of COPD. Small airway DUOX1 levels were decreased in advanced COPD, and correlated with loss of lung function and markers of emphysema and remodeling. Similarly, DUOX1 downregulation in correlation with extracellular matrix remodeling was observed in a genetic model of COPD, transgenic SPC-TNF-α mice. Finally, development of subepithelial airway fibrosis in mice due to exposure to the CS-component acrolein, or alveolar emphysema induced by administration of elastase, were in both cases exacerbated in Duox1-deficient mice. Collectively, our studies highlight that downregulation of DUOX1 may be a contributing feature of COPD pathogenesis, likely related to impaired DUOX1-mediated innate injury responses involved in epithelial homeostasis.
Authors
Caspar Schiffers, Cheryl van de Wetering, Robert A. Bauer, Aida Habibovic, Milena Hristova, Christopher M. Dustin, Sara Lambrichts, Pamela M. Vacek, Emiel F.M. Wouters, Niki L. Reynaert, Albert van der Vliet
Abstract
Existing animal models of cystic fibrosis (CF) have provided key insights into CF pathogenesis but have been limited by short life spans, absence of key phenotypes, and/or high maintenance costs. Here, we report the CRISPR/Cas9-mediated generation of CF rabbits, a model with a relatively long lifespan and affordable maintenance and care costs. CF rabbits supplemented solely with oral osmotic laxative had a median survival of ~ 40 days and died of gastrointestinal disease, but therapeutic regimens aimed at restoring gastrointestinal transit extended median survival to ~ 80 days. Surrogate markers of exocrine pancreas disorders were found in CF rabbits with declining health. CFTR expression pattern in WT rabbit airways mimicked humans, with widespread distribution in nasal respiratory and olfactory epithelia, as well as proximal and distal lower airways. CF rabbits exhibited human CF-like abnormalities in the bioelectric properties of the upper and lower airways. No spontaneous respiratory disease was detected in young CF rabbits. However, abnormal phenotypes were observed in surviving 1 year-old CF rabbits as compared to WT littermates, which were especially evident in the nasal respiratory and olfactory epithelium. The CF rabbit model may serve as a useful tool for understanding gut and lung CF pathogenesis and for the practical development of CF therapeutics.
Authors
Jie Xu, Alessandra Livraghi-Butrico, Xia Hou, Carthic Rajagopalan, Jifeng Zhang, Jun Song, Hong Jiang, Hong-guang Wei, Hui Wang, Mohamad Bouhamdan, Jinxue Ruan, Dongshan Yang, Yining Qiu, Xie Youming, Ronald P. Barrett, Sharon A. McClellan, Hongmei Mou, Qingtian Wu, Xuequn Chen, Troy D. Rogers, Kristen J. Wilkinson, Rodney C. Gilmore, Charles R. Esther Jr., Khalequz Zaman, Xiubin Liang, Michael Sobolic, Linda Hazlett, Kezhong Zhang, Raymond A. Frizzell, Martina Gentzsch, Wanda K. O'Neal, Barbara R. Grubb, Y Eugene Chen, Richard C. Boucher, Fei Sun
Abstract
Evidence for reduced expression of cyclin G associated kinase (GAK) in glomeruli of patients with chronic kidney disease was observed in the Nephroseq human database, and GAK was found to be associated with the decline in kidney function. To examine the role of GAK, a protein that functions to uncoat clathrin during endocytosis, we generated podocyte-specific Gak-knockout mice (Gak-KO), which developed progressive proteinuria and kidney failure with global glomerulosclerosis. We isolated glomeruli from the mice carrying the mutation to perform messenger RNA profiling and unearthed evidence for dysregulated podocyte calpain protease activity as an important contributor to progressive podocyte damage. Treatment with calpain inhibitor III specifically inhibited calpain-1/-2 activities, mitigated the degree of proteinuria and glomerulosclerosis, and led to a striking increase in survival in the Gak-KO mice. Podocyte-specific deletion of Capns1, essential for calpain-1 and calpain-2 activities, also improved proteinuria and glomerulosclerosis in Gak-KO mice. Increased podocyte calpain activity–mediated proteolysis of IκBα resulted in increased NF-κB p65–induced expression of growth arrest and DNA-damage-inducible 45 beta in the Gak-KO mice. Our results suggest that loss of podocyte-associated Gak induces glomerular injury secondary to calcium dysregulation and aberrant calpain activation, which when inhibited, can provide a protective role.
Authors
Xuefei Tian, Kazunori Inoue, Yan Zhang, Ying Wang, C. John Sperati, Christopher E. Pedigo, Tingting Zhao, Meihua Yan, Marwin Groener, Dennis G. Moledina, Karen Ebenezer, Wei Li, Zhenhai Zhang, Dan A. Liebermann, Lois Greene, Peter Greer, Chirag R. Parikh, Shuta Ishibe
Abstract
While autoantibodies are used in the diagnosis of rheumatoid arthritis (RA), the function of B cells in the inflamed joint remains elusive. Extensive flow cytometric characterization and SPICE algorithm analyses of single-cell synovial tissue from patients with RA revealed the accumulation of switched and double-negative memory programmed death-1 receptor–expressing (PD-1–expressing) B cells at the site of inflammation. Accumulation of memory B cells was mediated by CXCR3, evident by the observed increase in CXCR3-expressing synovial B cells compared with the periphery, differential regulation by key synovial cytokines, and restricted B cell invasion demonstrated in response to CXCR3 blockade. Notably, under 3% O2 hypoxic conditions that mimic the joint microenvironment, RA B cells maintained marked expression of MMP-9, TNF, and IL-6, with PD-1+ B cells demonstrating higher expression of CXCR3, CD80, CD86, IL-1β, and GM-CSF than their PD-1– counterparts. Finally, following functional analysis and flow cell sorting of RA PD-1+ versus PD-1– B cells, we demonstrate, using RNA-Seq and emerging fluorescence lifetime imaging microscopy of cellular NAD, a significant shift in metabolism of RA PD-1+ B cells toward glycolysis, associated with an increased transcriptional signature of key cytokines and chemokines that are strongly implicated in RA pathogenesis. Our data support the targeting of pathogenic PD-1+ B cells in RA as a focused, novel therapeutic option.
Authors
Achilleas Floudas, Nuno Neto, Viviana Marzaioli, Kieran Murray, Barry Moran, Michael G. Monaghan, Candice Low, Ronan H. Mullan, Navin Rao, Vinod Krishna, Sunil Nagpal, Douglas J. Veale, Ursula Fearon
Abstract
Ongoing societal changes in views on medical and recreational roles of cannabis increased the use of concentrated plant extracts with a Δ9-tetrahydrocannabinol (THC) content of >90%. Even though prenatal THC exposure is widely considered adverse for neuronal development, equivalent experimental data for young age cohorts are largely lacking. Here, we administered plant-derived THC (1 or 5 mg/kg) to mice daily during postnatal days (P)5-16 and P5-35 and monitored its effects on hippocampal neuronal survival and specification by high resolution imaging and the hippocampal proteome by iTRAQ proteomics, respectively. We find that THC indiscriminately affects pyramidal cells and both cannabinoid receptor 1 (CB1R)+ and CB1R- interneurons by P16. THC particularly disrupted the expression of mitochondrial proteins (complexes I-IV), a change that had persisted even 4 months after the end of drug exposure. This was reflected by a THC-induced loss of membrane integrity occluding mitochondrial respiration and could be partially or completely rescued by pH stabilization, antioxidants, bypassed glycolysis, and targeting either mitochondrial soluble adenylyl cyclase or the mitochondrial voltage-dependent anion channel. Overall, THC exposure during infancy induces significant and long-lasting reorganization of neuronal circuits through mechanisms that, in a large part, render cellular bioenergetics insufficient to sustain key developmental processes in otherwise healthy neurons.
Authors
Johannes Beiersdorf, Zsofia Hevesi, Daniela Calvigioni, Jakob Pyszkowski, Roman A. Romanov, Edit Szodorai, Gert Lubec, Sally L. Shirran, Catherine H. Botting, Siegfried Kasper, Geoffrey W. Guy, Roy A. Gray, Vincenzo Di Marzo, Tibor Harkany, Erik Keimpema
Abstract
Caspase 8 (CASP8) is one of the most frequently mutated genes in head and neck squamous carcinomas (HNSCC), and CASP8 mutations are associated with poor survival. The distribution of these mutations in HNSCC suggests that they are likely to be inactivating. Inhibition of CASP8 has been reported to sensitize cancer cells to necroptosis, a regulated cell death mechanism. Here, we show that knockdown of CASP8 renders HNSCCs susceptible to necroptosis by a second mitochondria-derived activator of caspase (SMAC) mimetic, Birinapant, in combination with pan-caspase inhibitors zVAD FMK or Emricasan and radiation. In a syngeneic mouse model of oral cancer, Birinapant, particularly when combined with radiation delayed tumor growth and enhanced survival under CASP8 loss. Exploration of molecular underpinnings of necroptosis sensitivity confirmed that the level of functional receptor-interacting serine/threonine-protein kinase 3 (RIP3) determines susceptibility to this mode of death. Although an in vitro screen revealed that low RIP3 levels render many HNSCC cell lines resistant to necroptosis, patient tumors maintain RIP3 expression and should therefore remain sensitive. Collectively, these results suggest that targeting the necroptosis pathway with SMAC mimetics, especially in combination with radiation, may be relevant therapeutically in HNSCC with compromised CASP8 status, provided that RIP3 function is maintained.
Authors
Burak Uzunparmak, Meng Gao, Antje Lindemann, Kelly Erikson, Li Wang, Eric Lin, Steven J. Frank, Frederico O. Gleber-Netto, Mei Zhao, Heath D. Skinner, Jared M. Newton, Andrew G. Sikora, Jeffrey N. Myers, Curtis R. Pickering
Abstract
Although congenital heart defects (CHDs) represent the most common birth defect, a comprehensive understanding of disease etiology remains unknown. This is further complicated since CHDs can occur in isolation or as a feature of another disorder. Analyzing disorders with associated CHDs provides a powerful platform to identify primary pathogenic mechanisms driving disease. Aberrant localization and expression of cathepsin proteases can perpetuate later-stage heart diseases, but their contribution toward CHDs is unclear. To investigate the contribution of cathepsins during cardiovascular development and congenital disease, we analyzed the pathogenesis of cardiac defects in zebrafish models of the lysosomal storage disorder mucolipidosis II (MLII). MLII is caused by mutations in the GlcNAc-1-phosphotransferase enzyme (Gnptab) that disrupt carbohydrate-dependent sorting of lysosomal enzymes. Without Gnptab, lysosomal hydrolases, including cathepsin proteases, are inappropriately secreted. Analyses of heart development in gnptab-deficient zebrafish show cathepsin K secretion increases its activity, disrupts TGF-β–related signaling, and alters myocardial and valvular formation. Importantly, cathepsin K inhibition restored normal heart and valve development in MLII embryos. Collectively, these data identify mislocalized cathepsin K as an initiator of cardiac disease in this lysosomal disorder and establish cathepsin inhibition as a viable therapeutic strategy.
Authors
Po-Nien Lu, Trevor Moreland, Courtney J. Christian, Troy C. Lund, Richard A. Steet, Heather Flanagan-Steet
Abstract
Actin-associated nonmuscle myosin II (NM2) motor proteins play critical roles in a myriad of cellular functions including endocytosis and organelle transport pathways. Cell type-specific expression and unique subcellular localization of the NM2 proteins, encoded by the Myh9 and Myh10 genes, in the mouse kidney tubules led us to hypothesize that these proteins have specialized functional roles within the renal epithelium. Inducible, conditional knockout (cKO) of Myh9 and Myh10 in the renal tubules of adult mice resulted in progressive kidney disease. Prior to overt renal tubular injury, we observed intracellular accumulation of the GPI-anchored protein uromodulin and gradual loss of Na+ K+ 2Cl- cotransporter from the apical membrane of the thick ascending limb (TAL) epithelia. The UMOD accumulation coincided with expansion of endoplasmic reticulum (ER) tubules, activation of ER stress and unfolded protein response pathways in Myh9&10 cKO kidneys. We conclude that NM2 proteins are required for localization and transport of UMOD and loss of function results in accumulation of UMOD and ER stress mediated progressive renal tubulointerstitial disease. These observations establish cell type-specific role(s) for NM2 proteins in regulation of specialized renal epithelial transport pathways and reveal the possibility that human kidney disease associated with MYH9 mutations could be of renal epithelial origin..
Authors
Karla L. Otterpohl, Brook W. Busselman, Ishara Ratnayake, Ryan G. Hart, Kimberly Hart, Claire Evans, Carrie L. Phillips, Jordan R. Beach, Phil Ahrenkiel, Bruce Molitoris, Kameswaran Surendran, Indra Chandrasekar
Abstract
The ability of HDL to inhibit inflammation in adipocytes and adipose tissue is reduced when HDL contains serum amyloid A (SAA) due to trapping of SAA in HDL by proteoglycans at the adipocyte surface. Since we recently found that the major extracellular matrix proteoglycan produced by hypertrophic adipocytes is versican, whereas activated adipose tissue macrophages produce mainly biglycan, the role of proteoglycans in determining the anti-inflammatory properties of HDL was further investigated. The distribution of versican, biglycan, apolipoprotein A-I (the major apolipoprotein of HDL) and SAA were similar in adipose tissue from obese mice and obese human subjects. Co-localization of SAA-enriched HDL with versican and biglycan at the cell surface of adipocyte and peritoneal macrophages, respectively, was blocked by silencing these proteoglycans, which also restored the anti-inflammatory property of SAA-enriched HDL despite the presence of SAA. Similar to adipocytes, normal HDL exerts its anti-inflammatory function in macrophages by reducing lipid rafts, reactive oxygen species generation and translocation of toll like receptor 4 and NADPH oxidase 2 into lipid rafts, effects that are not observed with SAA-enriched HDL. These findings imply that SAA present in HDL can be trapped by adipocyte-derived versican and macrophage-derived biglycan, thereby blunting HDL’s anti-inflammatory properties.
Authors
Chang Yeop Han, Inkyung Kang, Mohamed Omer, Shari Wang, Tomasz Wietecha, Thomas N. Wight, Alan Chait
Abstract
Ischemia-reperfusion-induced edema (IRE) one of the most significant causes of mortality after lung transplantation can be mimicked ex-vivo in isolated perfused mouse lungs (IPL). Transient receptor potential vanilloid 4 (TRPV4) is a non-selective cation channel studied in endothelium, while its role in the lung epithelium remains elusive. Here we show enhanced IRE in TRPV4-deficient (TRPV4–/–) IPL compared to wild-type (WT) controls, indicating a protective role of TRPV4 to maintain the alveolar epithelial barrier. By immunohistochemistry, mRNA profiling and electrophysiological characterization, we detected TRPV4 in bronchial epithelium, alveolar type I (ATI) and alveolar type II (ATII) cells. Genetic ablation of TRPV4 resulted in reduced expression of the water conducting aquaporin-5 (AQP-5) channel in ATI cells. Migration of TRPV4–/– ATI cells was reduced and cell barrier function was impaired. Analysis of isolated primary TRPV4-deficient ATII cells revealed a reduced expression of surfactant protein C (SP-C) and the TRPV4 activator GSK1016790A induced increases in current densities only in WT ATII cells. Moreover, TRPV4–/– lungs of adult mice developed significantly larger mean chord lengths and altered lung function compared to WT lungs. Therefore, our data discover essential functions of TRPV4 channels in alveolar epithelial cells and in the protection from edema formation.
Authors
Jonas Weber, Suhasini Rajan, Christian Schremmer, Yu-Kai Chao, Gabriela Krasteva-Christ, Martina Kannler, Ali Önder Yildirim, Monika Brosien, Johann Schredelseker, Norbert Weissmann, Christian Grimm, Thomas Gudermann, Alexander Dietrich
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