Lung vitamin E transport processes are affected by both age and environmental oxidants in mice.
Despite the physiological importance of alpha-tocopherol (AT), the molecular mechanisms involved in maintaining cellular and tissue tocopherol levels remain to be fully characterized. Scavenger receptor B1 (SRB1), one of a large family of scavenger receptors, has been shown to facilitate AT transfer from HDL to peripheral tissues via apo A-1-mediated processes and to be important in the delivery of AT to the lung cells. In the present studies the effects of age and two environmental oxidants ozone (O(3)) (0.25 ppm 6 h/day) and cigarette smoke (CS) (60 mg/m(3) 6 h/day) for 4 days on selected aspects of AT transport in murine lung tissues were assessed. While AT levels were 25% higher (p<0.05) and 15% lower (p<0.05) in plasma and lung tissue, respectively, in aged versus young mice, acute environmental exposure to O(3) or CS at the doses used had no effect. Gene expression levels, determined by RT-PCR of AT transport protein (ATTP), SRB1, CD36, ATP binding cassette 3 (ABCA3) and ABCA1 and protein levels, determined by Western blots for SRB1, ATTP and ABCA1 were assessed. Aged mouse lung showed a lower levels of ATTP, ABCA3 and SRB1 and a higher level CD36 and ABCA1. Acute exposure to either O(3) or CS induced declines in ATTP and SRB1 in both aged and young mice lung. CD36 increased in both young and aged mice lung upon exposure to O(3) and CS. These findings suggest that both age and environmental oxidant exposure affect pathways related to lung AT homeostasis and do so in a way that favors declines in lung AT. However, given the approach taken, the effects cannot be traced to changes in these pathways or AT content in any specific lung associated cell type and thus highlight the need for further follow-up studies looking at specific lung associated cell types.
Valacchi
Giuseppe
G
Center for Comparative Respiratory Biology and Medicine, Department of Internal Medicine, University of California Davis, Davis, CA 95616, USA. gvalacchi@ucdavis.edu
Vasu
Vihas T
VT
Yokohama
Wallace
W
Corbacho
Ana M
AM
Phung
Anh
A
Lim
Yunsook
Y
Aung
Hnin Hnin
HH
Cross
Carroll E
CE
Davis
Paul A
PA
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism; D000375:Aging; D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D015153:Blotting, Western; D018955:CD36 Antigens / Q000235:genetics / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling / Q000379:methods; D008074:Lipoproteins / Q000097:blood; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008812:Mice, Hairless; D010083:Oxidants, Photochemical / Q000737:chemistry / Q000494:pharmacology*; D010126:Ozone / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051122:Scavenger Receptors, Class B / Q000235:genetics / Q000378:metabolism; D012906:Smoke; D014026:Nicotiana / Q000737:chemistry; D014810:Vitamin E / Q000378:metabolism*
D064286:ATP Binding Cassette Transporter 1; D018528:ATP-Binding Cassette Transporters; C512026:Abca3 protein, mouse; D018955:CD36 Antigens; D008074:Lipoproteins; D010083:Oxidants, Photochemical; D012333:RNA, Messenger; C454739:Scarb1 protein, mouse; D051122:Scavenger Receptors, Class B; D012906:Smoke; D014810:Vitamin E; D010126:Ozone