title: Age-related activation of MKK/p38/NF-κB signaling pathway in lung: from mouse to human.
abstract: We and others previously reported that the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6 significantly accumulate with age in mouse lung. This is accompanied by elevated phosphorylation of p38. Here, we further investigate whether aging affects activation of p38 signaling and the inflammatory reaction after exposure to lipopolysaccharide (LPS) in the lungs of mice in vivo and humans ex vivo. The data showed that activation of p38 peaked at 0.5h and then rapidly declined in young (2-month-old) mouse lung, after intranasal inhalation challenge with LPS. In contract, activation of p38 peaked at 24h and was sustained longer in aged (20-month-old) mice. As well as altered p38, activations of its upstream activator MKK and downstream substrate NF-κB were also changed in the lungs of aged mice, which corresponded with the absence in the early phase but delayed increases in concentrations of TNF-α, IL-1β and IL-6. Consistent with the above observations in mice, similar patterns of p38 signaling also occurred in human lungs. Compared with younger lungs from adult-middle aged subjects, the activation of p38, MKK and NF-κB, as well as the production of pro-inflammatory cytokines were significantly increased in the lungs of older subjects ex vivo. Exposure of human lung cells to LPS induced rapid activation of p38, MKK and NF-κB in these cells from adult-middle aged subjects, but not older subjects, with increases in the production of the pro-inflammatory cytokines. The LPS-induced rapid activation in the lung cells from adult-middle aged subjects occurred as early as 0.25h after exposure, and then declined. Compared with adult-middle aged subjects, the LPS exposure did not induce marked changes in the early phase, either in the activation of p38, MKK and NF-κB, or in the production of TNF-α, IL-1β or IL-6 in the lung cells from older subjects. In contrast, these changes occurred relatively late, peaked at 16h and were sustained longer in the lungs of older subjects. These data support the hypothesis that the sustained activation of the p38 signaling pathway at baseline and the absence in the early phase but delayed of p38 signaling pathway response to LPS in the elderly may play important roles in increased susceptibility of aged lungs to inflammatory injury.
authors.affiliation: Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Department of Pulmonary and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China; Beijing Institute of Respiratory Medicine, Beijing 100020, PR China.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Ren
authors.affiliation: Department of Thoracic Surgery, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China.
authors.forename: Huadong
authors.initials: H
authors.lastname: Du
authors.affiliation: Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Department of Pulmonary and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China; Beijing Institute of Respiratory Medicine, Beijing 100020, PR China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.affiliation: Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Department of Pulmonary and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China; Beijing Institute of Respiratory Medicine, Beijing 100020, PR China.
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Yao
authors.affiliation: Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Department of Pulmonary and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China; Beijing Institute of Respiratory Medicine, Beijing 100020, PR China.
authors.forename: Junmin
authors.initials: J
authors.lastname: Huang
authors.affiliation: Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Department of Pulmonary and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China; Beijing Institute of Respiratory Medicine, Beijing 100020, PR China.
authors.forename: Zongli
authors.initials: Z
authors.lastname: Li
authors.affiliation: Department of Immunology, Capital Medical University, Beijing 100069, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.affiliation: Department of Neurobiology, Beijing Institute for Brain Disorders, Capital Medical University, Beijing 100069, PR China.
authors.forename: Junfa
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Neurobiology, Beijing Institute for Brain Disorders, Capital Medical University, Beijing 100069, PR China.
authors.forename: Song
authors.initials: S
authors.lastname: Han
authors.affiliation: Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Department of Pulmonary and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China; Beijing Institute of Respiratory Medicine, Beijing 100020, PR China.
authors.forename: Chen
authors.initials: C
authors.lastname: Wang
authors.affiliation: Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, Department of Pulmonary and Critical Care Medicine, Beijing Chao-Yang Hospital, Capital Medical University, Beijing 100020, PR China; Beijing Institute of Respiratory Medicine, Beijing 100020, PR China. Electronic address: kewuhuang@126.com.
authors.forename: Kewu
authors.initials: K
authors.lastname: Huang
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D016207:Cytokines / Q000378:metabolism; D006801:Humans; D008070:Lipopolysaccharides; D008168:Lung / Q000378:metabolism* / Q000473:pathology; D020935:MAP Kinase Signaling System; D008297:Male; D008810:Mice, Inbred C57BL; D008875:Middle Aged; D016328:NF-kappa B / Q000378:metabolism; D013312:Stress, Physiological; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D016207:Cytokines; D008070:Lipopolysaccharides; D016328:NF-kappa B; C061901:GLB1 protein, human; D001616:beta-Galactosidase
keywords: Cytokines; Inflammaging; Lipopolysaccharide; Lung; P38