IL13 activates autophagy to regulate secretion in airway epithelial cells
TL;DR: It is indicated that autophagy is essential for airway mucus secretion in a type 2, IL13-dependent immune disease process and thereby provide a novel therapeutic strategy for attenuating airway obstruction in hypersecretory inflammatory diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis lung disease.
Abstract: Cytokine modulation of autophagy is increasingly recognized in disease pathogenesis, and current concepts suggest that type 1 cytokines activate autophagy, whereas type 2 cytokines are inhibitory. However, this paradigm derives primarily from studies of immune cells and is poorly characterized in tissue cells, including sentinel epithelial cells that regulate the immune response. In particular, the type 2 cytokine IL13 (interleukin 13) drives the formation of airway goblet cells that secrete excess mucus as a characteristic feature of airway disease, but whether this process is influenced by autophagy was undefined. Here we use a mouse model of airway disease in which IL33 (interleukin 33) stimulation leads to IL13-dependent formation of airway goblet cells as tracked by levels of mucin MUC5AC (mucin 5AC, oligomeric mucus/gel forming), and we show that these cells manifest a block in mucus secretion in autophagy gene Atg16l1-deficient mice compared to wild-type control mice. Similarly, primary-culture human tracheal epithelial cells treated with IL13 to stimulate mucus formation also exhibit a block in MUC5AC secretion in cells depleted of autophagy gene ATG5 (autophagy-related 5) or ATG14 (autophagy-related 14) compared to nondepleted control cells. Our findings indicate that autophagy is essential for airway mucus secretion in a type 2, IL13-dependent immune disease process and thereby provide a novel therapeutic strategy for attenuating airway obstruction in hypersecretory inflammatory diseases such as asthma, chronic obstructive pulmonary disease, and cystic fibrosis lung disease. Taken together, these observations suggest that the regulation of autophagy by Th2 cytokines is cell-context dependent.
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TL;DR: Progress in elucidating mechanisms of crosstalk between autophagy and inflammatory signalling cascades is reviewed and improved mechanistic understanding of the autophagic machinery offers hope for treating infectious and inflammatory diseases.
Abstract: This article provides a comprehensive overview of the general functions of autophagy in immunity, the interactions between autophagy and immune signalling pathways and the role of autophagy–immune crosstalk in multicellular immune responses and disease.
309 citations
TL;DR: The role of autophagy in driving and regulating inflammatory responses of the lung in chronic lung diseases with a focus on potential avenues for therapeutic targeting is discussed.
Abstract: Persistent inflammation within the respiratory tract underlies the pathogenesis of numerous chronic pulmonary diseases including chronic obstructive pulmonary disease, asthma and pulmonary fibrosis. Chronic inflammation in the lung may arise from a combination of genetic susceptibility and environmental influences, including exposure to microbes, particles from the atmosphere, irritants, pollutants, allergens, and toxic molecules. To this end, an immediate, strong, and highly regulated inflammatory defense mechanism is needed for the successful maintenance of homeostasis within the respiratory system. Macroautophagy/autophagy plays an essential role in the inflammatory response of the lung to infection and stress. At baseline, autophagy may be critical for inhibiting spontaneous pulmonary inflammation and fundamental for the response of pulmonary leukocytes to infection; however, when not regulated, persistent or inefficient autophagy may be detrimental to lung epithelial cells, promoting lung injury. This perspective will discuss the role of autophagy in driving and regulating inflammatory responses of the lung in chronic lung diseases with a focus on potential avenues for therapeutic targeting. Abbreviations AR allergic rhinitis AM alveolar macrophage ATG autophagy-related CF cystic fibrosis CFTR cystic fibrosis transmembrane conductance regulator COPD chronic obstructive pulmonary disease CS cigarette smoke CSE cigarette smoke extract DC dendritic cell IH intermittent hypoxia IPF idiopathic pulmonary fibrosis ILD interstitial lung disease MAP1LC3B microtubule associated protein 1 light chain 3 beta MTB Mycobacterium tuberculosis MTOR mechanistic target of rapamycin kinase NET neutrophil extracellular traps OSA obstructive sleep apnea PAH pulmonary arterial hypertension PH pulmonary hypertension ROS reactive oxygen species TGFB1 transforming growth factor beta 1 TNF tumor necrosis factor.
278 citations
Cites background from "IL13 activates autophagy to regulat..."
...At baseline, autophagy in AMs is critical for inhibiting spontaneous pulmonary inflammation(11) and is fundamental for airway mucus secretion by airway goblet cells.(12) Autophagydeficient mice (atg5¡/¡ and atg7¡/¡) develop spontaneous sterile lung inflammation, characterized by marked recruitment of inflammatory cells submucosal thickening, goblet cell metaplasia, and increased collagen content....
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TL;DR: In this article, the authors discuss regional differences in mucus composition, mucus physicochemical properties, such as pore size, viscoelasticity, pH, and ionic strength.
264 citations
TL;DR: Insight into the innate immune properties of mucins and goblet cells support a shift from the current paradigm of repressing increased mucin expression to targeting regulation of specific mucins or mucin hyperconcentration in the abnormal airway milieu.
220 citations
TL;DR: This review highlights the current understanding on the interplay between ROS and autophagy in the development of pulmonary disease and suggests a central role for autophile as a mammalian oxidative stress response and its interrelationship to other stress defense systems.
Abstract: The autophagic pathway involves the encapsulation of substrates in double-membraned vesicles, which are subsequently delivered to the lysosome for enzymatic degradation and recycling of metabolic precursors. Autophagy is a major cellular defense against oxidative stress, or related conditions that cause accumulation of damaged proteins or organelles. Selective forms of autophagy can maintain organelle populations or remove aggregated proteins. Dysregulation of redox homeostasis under pathological conditions results in excessive generation of reactive oxygen species (ROS), leading to oxidative stress and the associated oxidative damage of cellular components. Accumulating evidence indicates that autophagy is necessary to maintain redox homeostasis. ROS activates autophagy, which facilitates cellular adaptation and diminishes oxidative damage by degrading and recycling intracellular damaged macromolecules and dysfunctional organelles. The cellular responses triggered by oxidative stress include the altered regulation of signaling pathways that culminate in the regulation of autophagy. Current research suggests a central role for autophagy as a mammalian oxidative stress response and its interrelationship to other stress defense systems. Altered autophagy phenotypes have been observed in lung diseases such as chronic obstructive lung disease, acute lung injury, cystic fibrosis, idiopathic pulmonary fibrosis, and pulmonary arterial hypertension, and asthma. Understanding the mechanisms by which ROS regulate autophagy will provide novel therapeutic targets for lung diseases. This review highlights our current understanding on the interplay between ROS and autophagy in the development of pulmonary disease.
137 citations
Cites background from "IL13 activates autophagy to regulat..."
...Genetic depletion of ATG5 and ATG14 or pharmacological inhibition of autophagy with 3-MA or bafilomycin A1 (Baf-A1) in epithelial cells treated with IL13 results in less mucus secretion and less CCL26 (eosinophil chemokine) production, demonstrating that autophagy is involved in the activation of the Th2 response in asthma [343]....
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References
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TL;DR: The origins, challenges and solutions of NIH Image and ImageJ software are discussed, and how their history can serve to advise and inform other software projects.
Abstract: For the past 25 years NIH Image and ImageJ software have been pioneers as open tools for the analysis of scientific images. We discuss the origins, challenges and solutions of these two programs, and how their history can serve to advise and inform other software projects.
44,587 citations
TL;DR: A crucial role is revealed for the autophagy pathway and proteins in immunity and inflammation, and they balance the beneficial and detrimental effects of immunity andinflammation, and thereby may protect against infectious, autoimmune and inflammatory diseases.
Abstract: Autophagy is an essential, homeostatic process by which cells break down their own components. Perhaps the most primordial function of this lysosomal degradation pathway is adaptation to nutrient deprivation. However, in complex multicellular organisms, the core molecular machinery of autophagy - the 'autophagy proteins' - orchestrates diverse aspects of cellular and organismal responses to other dangerous stimuli such as infection. Recent developments reveal a crucial role for the autophagy pathway and proteins in immunity and inflammation. They balance the beneficial and detrimental effects of immunity and inflammation, and thereby may protect against infectious, autoimmune and inflammatory diseases.
2,757 citations
"IL13 activates autophagy to regulat..." refers background in this paper
...Of these, cytokines are increasingly recognized as potent modulators of autophagy, capable of both activation and inhibition during inflammation.(1,2) Cytokine regulation of autophagy may occur as a component of the immune response to pathogens or in noninfectious disorders such as atherosclerosis or malignancy....
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TL;DR: The targeted pulmonary expression of IL-13 causes a mononuclear and eosinophilic inflammatory response, mucus cell metaplasia, airway fibrosis, eotaxin production, airways obstruction, and nonspecific AHR in transgene-positive animals.
Abstract: Interleukin (IL)-13 is a pleiotropic cytokine produced in large quantities by activated CD4+ Th2 lymphocytes. To define further its potential in vivo effector functions, the Clara cell 10-kDa protein promoter was used to express IL-13 selectively in the lung, and the phenotype of the resulting transgenic mice was characterized. In contrast to transgene-negative littermates, the lungs of transgene-positive mice contained an inflammatory response around small and large airways and in the surrounding parenchyma. It was mononuclear in nature and contained significant numbers of eosinophils and enlarged and occasionally multinucleated macrophages. Airway epithelial cell hypertrophy, mucus cell metaplasia, the hyperproduction of neutral and acidic mucus, the deposition of Charcot-Leyden‐like crystals, and subepithelial airway fibrosis were also prominently noted. Eotaxin protein and mRNA were also present in large quantities in the lungs of the transgene-positive, but not the transgene-negative, mice. IL-4, IL-5, granulocyte-macrophage colony-stimulating factor, and monocyte chemoattractant protein-5 were not similarly detected. Physiological evaluations revealed significant increases in baseline airways resistance and airways hyperresponsiveness (AHR) to methacholine in transgene-positive animals. Thus, the targeted pulmonary expression of IL-13 causes a mononuclear and eosinophilic inflammatory response, mucus cell metaplasia, the deposition of Charcot-Leyden‐like crystals, airway fibrosis, eotaxin production, airways obstruction, and nonspecific AHR. IL-13 may play an important role in the pathogenesis of similar responses in asthma or other Th2-polarized tissue responses. J. Clin. Invest. 103:779-788 (1999).
1,695 citations
TL;DR: ATG16L1, and probably the process of autophagy, have a role within the intestinal epithelium of mice and Crohn’s disease patients by selective effects on the cell biology and specialized regulatory properties of Paneth cells.
Abstract: Susceptibility to Crohn's disease, a complex inflammatory disease involving the small intestine, is controlled by over 30 loci. One Crohn's disease risk allele is in ATG16L1, a gene homologous to the essential yeast autophagy gene ATG16 (ref. 2). It is not known how ATG16L1 or autophagy contributes to intestinal biology or Crohn's disease pathogenesis. To address these questions, we generated and characterized mice that are hypomorphic for ATG16L1 protein expression, and validated conclusions on the basis of studies in these mice by analysing intestinal tissues that we collected from Crohn's disease patients carrying the Crohn's disease risk allele of ATG16L1. Here we show that ATG16L1 is a bona fide autophagy protein. Within the ileal epithelium, both ATG16L1 and a second essential autophagy protein ATG5 are selectively important for the biology of the Paneth cell, a specialized epithelial cell that functions in part by secretion of granule contents containing antimicrobial peptides and other proteins that alter the intestinal environment. ATG16L1- and ATG5-deficient Paneth cells exhibited notable abnormalities in the granule exocytosis pathway. In addition, transcriptional analysis revealed an unexpected gain of function specific to ATG16L1-deficient Paneth cells including increased expression of genes involved in peroxisome proliferator-activated receptor (PPAR) signalling and lipid metabolism, of acute phase reactants and of two adipocytokines, leptin and adiponectin, known to directly influence intestinal injury responses. Importantly, Crohn's disease patients homozygous for the ATG16L1 Crohn's disease risk allele displayed Paneth cell granule abnormalities similar to those observed in autophagy-protein-deficient mice and expressed increased levels of leptin protein. Thus, ATG16L1, and probably the process of autophagy, have a role within the intestinal epithelium of mice and Crohn's disease patients by selective effects on the cell biology and specialized regulatory properties of Paneth cells.
1,395 citations
"IL13 activates autophagy to regulat..." refers background or methods in this paper
...C57BL/6 mice deficient in the autophagy gene Atg16l1 were previously described (Atg16l1).(27) Mice were administered PBS (Sigma-Aldrich, P3813) vehicle or recombinant mouse IL33 (Peprotech, 210–33), 1....
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...Autophagy is now shown to be required for secretory pathways in mast cells, bone osteoclasts, intestinal Paneth cells, and colonic goblet cells.(27,28,50-52) Shared or unique utilization of specific autophagy proteins for secretion is yet to be resolved, Figure 5....
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...However, unlike the physiological requirement for goblet cells in the intestine, goblet cell differentiation in the mouse airway must be induced.(27) Airway goblet cell formation can be efficiently induced by airway delivery of IL33, which leads to macrophage and lymphocyte production of IL13....
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TL;DR: It is demonstrated that both Moloney leukemia virus and lentivirus vector-mediated expression of RNAi can achieve effective, stable gene silencing in diverse biological systems and will assist in elucidating gene functions in numerous cell types including primary cells.
Abstract: Genome-wide genetic approaches have proven useful for examining pathways of biological significance in model organisms such as Saccharomyces cerevisiae, Drosophila melanogastor, and Caenorhabditis elegans, but similar techniques have proven difficult to apply to mammalian systems. Although manipulation of the murine genome has led to identification of genes and their function, this approach is laborious, expensive, and often leads to lethal phenotypes. RNA interference (RNAi) is an evolutionarily conserved process of gene silencing that has become a powerful tool for investigating gene function by reverse genetics. Here we describe the delivery of cassettes expressing hairpin RNA targeting green fluorescent protein (GFP) using Moloney leukemia virus-based and lentivirus-based retroviral vectors. Both transformed cell lines and primary dendritic cells, normally refractory to transfection-based gene transfer, demonstrated stable silencing of targeted genes, including the tumor suppressor gene TP53 in normal human fibroblasts. This report demonstrates that both Moloney leukemia virus and lentivirus vector-mediated expression of RNAi can achieve effective, stable gene silencing in diverse biological systems and will assist in elucidating gene functions in numerous cell types including primary cells.
1,335 citations
"IL13 activates autophagy to regulat..." refers methods in this paper
...sequences in HEK293T cells using FuGENE 6 (Promega, E2691) as described.(62) Twenty h after transfection, the virus was collected in DMEM/F12 media with 5% fetal bovine serum then passed through a 45-micron filter (Millipore, CE0459)....
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