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A1193 - Beclin 1 Regulates Smoke Induced Kidney Injury in a Murine Model of Chronic Obstructive Pulmonary Disease
Author Block: M. A. Pabon1, E. A. Patino2, K. C. Ma3, E. Finkelsztein4, J. C. Osorio1, F. Malick5, K. Mizumura4, H. Lam6, F. Polverino7, C. A. Owen8, A. M. K. Choi9, S. M. Cloonan10, M. E. Choi2; 1Internal Medicine, New York Presbyterian Hospital - Weill Cornell Medicine, New York, NY, United States, 2Division of Nephrology and Hypertension, Weill Cornell Medicine, New York, NY, United States, 3New York Presbyterian Hospital - Weill Cornell Medicine, New York, NY, United States, 4Pulmonary and Critical Care Department, Weill Cornell Medicine, New York, NY, United States, 5Weill Cornell Medical College, New York, NY, United States, 6Brigham and Women s Hospital, Stoughton, MA, United States, 7Pulmonary and Critical Care, Brigham and Women's Hospital, Boston, MA, United States, 8Pulmonary Division, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States, 9Weill Cornell Medicine, New York, NY, United States, 10Pulmonary and Critical Care Department, Weill Cornell Medicine, New York City, NY, United States.
Rationale: Patients with chronic obstructive pulmonary disease (COPD) have a higher prevalence of chronic kidney disease (CKD) than that observed in the general population (Incalzi, Chest. 2010, Polverino, AJRCCM 2017), but the mechanisms associating chronic kidney dysfunction to smoke induced COPD remain unclear. Autophagy is a highly conserved cellular function which degrades damaged intracellular components via the lysosome, and is implicated in the pathogenesis of a variety of human diseases, including COPD. In the current study, we investigated the role of autophagy in cigarette smoke (CS)-induced kidney injury in a murine model of COPD. Methods: Age and sex matched wild type (WT) and Beclin 1 heterozygous (Becn1+/-) mice were exposed to room air (RA) or CS in a whole body exposure chambers for 6 months. In vivo autophagic activity in murine kidneys was determined by measurement of LC3-II turnover, following the intraperitoneal injection of the lysosomal inhibitor, leupeptin (40 mg/kg). Beclin 1 expression was assessed in whole kidney tissue homogenates by western blot analysis. Expression of the mitophagy proteins NDP52, Parkin and LC3B were measured in mitochondrial fractions. Kidney injury was assessed by Masson’s Trichrome and Sirius red staining, transmission electron microscopy (TEM) and Lipocalin-2 levels as assessed by ELISA. Oxidative damage was assessed by immunohistochemical (IHC) staining of nitrotyrosine and 8-Oxo-2'-deoxyguanosine residues. Results: CS exposure induced kidney fibrosis in WT mice, as determined by increased Masson’s Trichrome and Sirius red staining of kidney tissue sections, and increased fibronectin expression as assessed by western blot analysis. Increased nitrotyrosine and 8-Oxo-2'-deoxyguanosine residues by IHC (indicative of oxidative stress) and increased urinary Lipocalin-2 (marker of kidney injury) were observed in the CS-treated group compared to RA mice. CS exposure induced increased autophagic flux as determined by increased LC3-II expression after leupeptin injection and increased autophagosome formation assessed by TEM. Beclin 1 expression was reduced in the kidneys of CS-exposed mice. Becn1+/- mice displayed decreased CS-induced kidney fibrosis, indices of oxidative stress and kidney tissue injury compared to WT mice. Becn1+/- mice also demonstrated decreased levels of mitophagy proteins NDP52 and Parkin expression after CS exposure. Conclusion: In experimental murine model of COPD, we show that Beclin 1 may promote CS-induced kidney injury, and is associated with decreased mitophagy. These findings suggest potential new pathways by which CS can mediate the pathogenesis of COPD associated chronic kidney injury.