Autophagy augmentation alleviates cigarette smoke-induced CFTR-dysfunction, ceramide-accumulation and COPD-emphysema pathogenesis.

Abstract

In this study, we aimed to investigate precise mechanism(s) of sphingolipid-imbalance and resulting ceramide-accumulation in COPD-emphysema. Where, human and murine emphysema lung tissues or human bronchial epithelial cells (Beas2b) were used for experimental analysis. We found that lungs of smokers and COPD-subjects with increasing emphysema severity demonstrate sphingolipid-imbalance, resulting in significant ceramide-accumulation and increased ceramide/sphingosine ratio, as compared to non-emphysema/non-smoker controls. Next, we found a substantial increase in emphysema chronicity-related ceramide-accumulation in murine (C57BL/6) lungs, while sphingosine levels only slightly increased. In accordance, the expression of the acid ceramidase decreased after CS-exposure. Moreover, CS-induced (sub-chronic) ceramide-accumulation was significantly (p < 0.05) reduced by treatment with TFEB/autophagy-inducing drug, gemfibrozil (GEM), suggesting that autophagy regulates CS-induced ceramide-accumulation. Next, we validated experimentally that autophagy/lipophagy-induction using an anti-oxidant, cysteamine, significantly (p < 0.05) reduces CS-extract (CSE)-mediated intracellular-ceramide-accumulation in p62 + aggresome-bodies. In addition to intracellular-accumulation, we found that CSE also induces membrane-ceramide-accumulation by ROS-dependent acid-sphingomyelinase (ASM) activation and plasma-membrane translocation, which was significantly controlled (p < 0.05) by cysteamine (an anti-oxidant) and amitriptyline (AMT, an inhibitor of ASM). Cysteamine-mediated and CSE-induced membrane-ceramide regulation was nullified by CFTR-inhibitor-172, demonstrating that CFTR controls redox impaired-autophagy dependent membrane-ceramide accumulation. In summary, our data shows that CS-mediated autophagy/lipophagy-dysfunction results in intracellular-ceramide-accumulation, while acquired CFTR-dysfunction-induced ASM causes membrane ceramide-accumulation. Thus, CS-exposure alters the sphingolipid-rheostat leading to the increased membrane- and intracellular- ceramide-accumulation inducing COPD-emphysema pathogenesis that is alleviated by treatment with cysteamine, a potent anti-oxidant with CFTR/autophagy-augmenting properties.

• Authors: Manish Bodas, Garrett Pehote, David Silverberg, Erich Gulbins, Neeraj Vij
• Journal: Free radical biology & medicine (Free Radic Biol Med) Vol. 131 Pg. 81-97 (02 01 2019) ISSN: 1873-4596 [Electronic] United States
• PMID: 30500419 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: Copyright © 2018 Elsevier Inc. All rights reserved.

Chemical References

• Antioxidants
• CFTR protein, human
• Ceramides
• Complex Mixtures
• Hypolipidemic Agents
• Cystic Fibrosis Transmembrane Conductance Regulator
• Cysteamine
• Acid Ceramidase
• Gemfibrozil

Topics

• Acid Ceramidase (genetics, metabolism)
• Animals
• Antioxidants (pharmacology)
• Autophagy (drug effects, genetics)
• Bronchi (drug effects, metabolism, pathology)
• Case-Control Studies
• Cell Line
• Ceramides (metabolism)
• Complex Mixtures (isolation & purification, pharmacology)
• Cysteamine (pharmacology)
• Cystic Fibrosis Transmembrane Conductance Regulator (deficiency, genetics)
• Emphysema (drug therapy, genetics, metabolism, pathology)
• Epithelial Cells (drug effects, metabolism, pathology)
• Gemfibrozil (pharmacology)
• Gene Expression
• Humans
• Hypolipidemic Agents (pharmacology)
• Male
• Mice
• Mice, Inbred C57BL
• Pulmonary Disease, Chronic Obstructive (drug therapy, genetics, metabolism, pathology)
• Smoking (adverse effects)
• Tobacco (adverse effects, chemistry)