title: Receptor for advanced glycation end-products regulates lung fluid balance via protein kinase C-gp91(phox) signaling to epithelial sodium channels.
abstract: The receptor for advanced glycation end-products (RAGE), a multiligand member of the Ig family, may play a crucial role in the regulation of lung fluid balance. We quantified soluble RAGE (sRAGE), a decoy isoform, and advanced glycation end-products (AGEs) from the bronchoalveolar lavage fluid of smokers and nonsmokers, and tested the hypothesis that AGEs regulate lung fluid balance through protein kinase C (PKC)-gp91(phox) signaling to the epithelial sodium channel (ENaC). Human bronchoalveolar lavage samples from smokers showed increased AGEs (9.02 ± 3.03 μg versus 2.48 ± 0.53 μg), lower sRAGE (1,205 ± 292 pg/ml versus 1,910 ± 263 pg/ml), and lower volume(s) of epithelial lining fluid (97 ± 14 ml versus 133 ± 17 ml). sRAGE levels did not predict ELF volumes in nonsmokers; however, in smokers, higher volumes of ELF were predicted with higher levels of sRAGE. Single-channel patch clamp analysis of rat alveolar epithelial type 1 cells showed that AGEs increased ENaC activity measured as the product of the number of channels (N) and the open probability (Po) (NPo) from 0.19 ± 0.08 to 0.83 ± 0.22 (P = 0.017) and the subsequent addition of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl decreased ENaC NPo to 0.15 ± 0.07 (P = 0.01). In type 2 cells, human AGEs increased ENaC NPo from 0.12 ± 0.05 to 0.53 ± 0.16 (P = 0.025) and the addition of 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl decreased ENaC NPo to 0.10 ± 0.03 (P = 0.013). Using molecular and biochemical techniques, we observed that inhibition of RAGE and PKC activity attenuated AGE-induced activation of ENaC. AGEs induced phosphorylation of p47(phox) and increased gp91(phox)-dependent reactive oxygen species production, a response that was abrogated with RAGE or PKC inhibition. Finally, tracheal instillation of AGEs promoted clearance of lung fluid, whereas concomitant inhibition of RAGE, PKC, and gp91(phox) abrogated the response.
authors: 1 Nell Hodgson Woodruff School of Nursing.
authors: Charles A
authors: CA
authors: Downs
authors: Lisa H
authors: LH
authors: Kreiner
authors: Nicholle M
authors: NM
authors: Johnson
authors: Lou Ann
authors: LA
authors: Brown
authors: My N
authors: MN
authors: Helms
mesh_terms: D000818:Animals; D018893:Bronchoalveolar Lavage; D053503:Epithelial Sodium Channels / Q000378:metabolism*; D005260:Female; D017127:Glycation End Products, Advanced / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic / Q000378:metabolism*; D015398:Signal Transduction; D012907:Smoking / Q000009:adverse effects / Q000378:metabolism* / Q000473:pathology
chemical_list: D053503:Epithelial Sodium Channels; D017127:Glycation End Products, Advanced; D008562:Membrane Glycoproteins; D017382:Reactive Oxygen Species; D000067759:Receptor for Advanced Glycation End Products; D011971:Receptors, Immunologic; C056558:CYBB protein, human; C500593:Cybb protein, rat; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D011493:Protein Kinase C
keywords: acute respiratory distress syndrome; alveolar microenvironment; chronic obstructive pulmonary disease; lung injury; pulmonary edema