title: Combustion-derived flame generated ultrafine soot generates reactive oxygen species and activates Nrf2 antioxidants differently in neonatal and adult rat lungs.
abstract: BACKGROUND
  Urban particulate matter (PM) has been epidemiologically correlated with multiple cardiopulmonary morbidities and mortalities, in sensitive populations. Children exposed to PM are more likely to develop respiratory infections and asthma. Although PM originates from natural and anthropogenic sources, vehicle exhaust rich in polycyclic aromatic hydrocarbons (PAH) can be a dominant contributor to the PM2.5 and PM0.1 fractions and has been implicated in the generation of reactive oxygen species (ROS).
  
  
  OBJECTIVE
  Current studies of ambient PM are confounded by the variable nature of PM, so we utilized a previously characterized ethylene-combusted premixed flame particles (PFP) with consistent and reproducible physiochemical properties and 1) measured the oxidative potential of PFP compared to ambient PM, 2) determined the ability of PFPs to generate oxidative stress and activate the transcription factor using in vitro and ex vivo models, and 3) we correlated these responses with antioxidant enzyme expression in vivo.
  
  
  METHODS
  We compared oxidative stress response (HMOX1) and antioxidant enzyme (SOD1, SOD2, CAT, and PRDX6) expression in vivo by performing a time-course study in 7-day old neonatal and young adult rats exposed to a single 6-hour exposure to 22.4 μg/m3 PFPs.
  
  
  RESULTS
  We showed that PFP is a potent ROS generator that induces oxidative stress and activates Nrf2. Induction of the oxidative stress responsive enzyme HMOX1 in vitro was mediated through Nrf2 activation and was variably upregulated in both ages. Furthermore, antioxidant enzyme expression had age and lung compartment variations post exposure. Of particular interest was SOD1, which had mRNA and protein upregulation in adult parenchyma, but lacked a similar response in neonates.
  
  
  CONCLUSIONS
  We conclude that PFPs are effective ROS generators, comparable to urban ambient PM2.5, that induce oxidative stress in neonatal and adult rat lungs. PFPs upregulate a select set of antioxidant enzymes in young adult animals, that are unaffected in neonates. We conclude that the inability of neonatal animals to upregulate the antioxidant response may, in part, explain enhanced their susceptibility to ultrafine particles, such as PFP.
authors.affiliation: Center for Health and the Environment, University of California, One Shields Ave, Davis, CA 95616, USA.
authors.forename: Jackie K W
authors.initials: JK
authors.lastname: Chan
authors.forename: Jessica G
authors.initials: JG
authors.lastname: Charrier
authors.forename: Sean D
authors.initials: SD
authors.lastname: Kodani
authors.forename: Christoph F
authors.initials: CF
authors.lastname: Vogel
authors.forename: Sarah Y
authors.initials: SY
authors.lastname: Kado
authors.forename: Donald S
authors.initials: DS
authors.lastname: Anderson
authors.forename: Cort
authors.initials: C
authors.lastname: Anastasio
authors.forename: Laura S
authors.initials: LS
authors.lastname: Van Winkle
mesh_terms: D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000235:genetics / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D017930:Genes, Reporter; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics / Q000378:metabolism; D006801:Humans; D019570:Inhalation Exposure; D008168:Lung / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D018384:Oxidative Stress / Q000187:drug effects*; D010316:Particle Size; D054465:Peroxiredoxin VI / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D053260:Soot / Q000633:toxicity*; D013482:Superoxide Dismutase / Q000235:genetics / Q000378:metabolism; D000072105:Superoxide Dismutase-1; D013997:Time Factors; D014162:Transfection; D020298:U937 Cells; D000099156:Superoxide Dismutase 2
chemical_list: D000975:Antioxidants; D002374:Catalase; D006419:Heme Oxygenase (Decyclizing); D051267:NF-E2-Related Factor 2; D054465:Peroxiredoxin VI; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D053260:Soot; D013482:Superoxide Dismutase; D000072105:Superoxide Dismutase-1; D000099156:Superoxide Dismutase 2; C495637:Nfe2l2 protein, rat; C000606290:SOD1 protein, human; C515984:Prdx6 protein, rat; C491523:Hmox1 protein, rat; C000606292:Sod1 protein, rat
references.citation: Free Radic Biol Med. 2008 May 1;44(9):1689-99
references.pmid: 18313407
references.citation: Nat Protoc. 2008;3(6):1101-8
references.pmid: 18546601
references.citation: Toxicol Sci. 2004 Jan;77(1):135-41
references.pmid: 14600286
references.citation: Environ Health Perspect. 2002 Apr;110(4):349-53
references.pmid: 11940452
references.citation: J Biol Chem. 2009 May 15;284(20):13291-5
references.pmid: 19182219
references.citation: Am J Physiol Lung Cell Mol Physiol. 2013 May 15;304(10):L665-77
references.pmid: 23502512
references.citation: Inhal Toxicol. 2012 Jul;24(8):506-17
references.pmid: 22746400
references.citation: Pediatrics. 2004 Apr;113(4 Suppl):1092-6
references.pmid: 15060204
references.citation: Environ Health Perspect. 2003 Apr;111(4):455-60
references.pmid: 12676598
references.citation: J Biol Chem. 2004 Jul 30;279(31):32804-12
references.pmid: 15178682
references.citation: Am J Respir Cell Mol Biol. 1996 Jul;15(1):1-8
references.pmid: 8679213
references.citation: Annu Rev Pharmacol Toxicol. 2007;47:89-116
references.pmid: 16968214
references.citation: Atmos Environ (1994). 2012 Jan 1;46:665-668
references.pmid: 22267949
references.citation: Inhal Toxicol. 2010 Dec;22 Suppl 2:70-83
references.pmid: 20961279
references.citation: Environ Health Perspect. 2005 Nov;113(11):1536-41
references.pmid: 16263508
references.citation: Methods Mol Biol. 2000;132:365-86
references.pmid: 10547847
references.citation: J Biol Chem. 2010 Aug 20;285(34):26190-8
references.pmid: 20511222
references.citation: FEBS Lett. 2003 Dec 4;555(2):192-8
references.pmid: 14644414
references.citation: Am J Epidemiol. 2009 Dec 15;170(12):1494-501
references.pmid: 19897513
references.citation: Environ Sci Technol. 2009 Feb 1;43(3):922-7
references.pmid: 19245037
references.citation: J Immunol Methods. 2001 Jan 1;247(1-2):187-90
references.pmid: 11150549
references.citation: Nutrition. 2005 Jun;21(6):775-7
references.pmid: 15925305
references.citation: Drug Metab Dispos. 2005 Nov;33(11):1597-602
references.pmid: 16085760
references.citation: Chem Res Toxicol. 2001 Oct;14(10):1371-7
references.pmid: 11599928
references.citation: Environ Health Perspect. 1995 Sep;103 Suppl 6:7-12
references.pmid: 8549494
references.citation: Am J Respir Crit Care Med. 2003 Jun 15;167(12):1600-19
references.pmid: 12796054
references.citation: Cell Mol Biol (Noisy-le-grand). 2005 Oct 03;51(5):513-20
references.pmid: 16309574
references.citation: Eur Respir J. 1997 Apr;10(4):872-9
references.pmid: 9150327
references.citation: Clin Exp Allergy. 2006 Apr;36(4):440-7
references.pmid: 16630148
references.citation: Ann Epidemiol. 2009 Apr;19(4):257-63
references.pmid: 19344865
references.citation: Atmos Chem Phys. 2012 May 3;12(5):11317-11350
references.pmid: 23393494
references.citation: N Engl J Med. 1993 Dec 9;329(24):1753-9
references.pmid: 8179653
references.citation: Indoor Air. 2007 Apr;17(2):143-52
references.pmid: 17391237
references.citation: Environ Health Perspect. 2001 Jun;109 Suppl 3:395-403
references.pmid: 11427389
references.citation: J Immunol. 2004 Sep 1;173(5):3467-81
references.pmid: 15322212
references.citation: Biochemistry (Mosc). 2006 Sep;71(9):962-74
references.pmid: 17009949
references.citation: J Allergy Clin Immunol. 2008 Jul;122(1):78-85
references.pmid: 18485467
references.citation: Proc Natl Acad Sci U S A. 2004 Mar 16;101(11):3780-5
references.pmid: 15004285
references.citation: Am J Physiol Cell Physiol. 2010 Oct;299(4):C736-49
references.pmid: 20554909
references.citation: Environ Sci Technol. 2007 May 15;41(10):3775-80
references.pmid: 17547212
references.citation: Mol Endocrinol. 2007 Dec;21(12):2941-55
references.pmid: 17823304
references.citation: Am J Respir Cell Mol Biol. 2013 Jan;48(1):114-24
references.pmid: 23065132
references.citation: Cancer Lett. 2008 Oct 18;270(1):144-55
references.pmid: 18554780
references.citation: J Aerosol Med. 2002 Summer;15(2):189-201
references.pmid: 12184869
references.citation: Inhal Toxicol. 2005 Jun-Jul;17(7-8):355-85
references.pmid: 16020034
references.citation: J Appl Toxicol. 1984 Aug;4(4):219-21
references.pmid: 6208233
references.citation: Environ Res. 2005 Sep;99(1):40-7
references.pmid: 16053926
references.citation: Free Radic Biol Med. 2012 May 1;52(9):2038-46
references.pmid: 22401859
references.citation: Methods. 2001 Dec;25(4):402-8
references.pmid: 11846609
references.citation: J Appl Physiol (1985). 2010 Oct;109(4):1115-24
references.pmid: 20634362
references.citation: Atmos Chem Phys. 2011 Sep 16;11(18):9671-9682
references.pmid: 22121357
references.citation: Prog Clin Biol Res. 1983;140:75-91
references.pmid: 6369343
references.citation: Atmos Environ (1994). 2011 Nov;45(40):7555-7562
references.pmid: 22125412
references.citation: J Air Waste Manag Assoc. 2002 Sep;52(9):1032-42
references.pmid: 12269664
references.citation: Environ Health Perspect. 2004 Oct;112(14):1347-58
references.pmid: 15471724
references.citation: Toxicol Sci. 2007 Jan;95(1):63-73
references.pmid: 17060372
references.citation: Occup Environ Med. 1998 Nov;55(11):771-8
references.pmid: 9924455
references.citation: Am J Respir Cell Mol Biol. 2008 Aug;39(2):198-207
references.pmid: 18367723
references.citation: Am J Physiol. 1987 Jul;253(1 Pt 1):C66-70
references.pmid: 3037915
references.citation: Proc Natl Acad Sci U S A. 2012 Mar 27;109(13):5092-7
references.pmid: 22411799
references.citation: Nat Clin Pract Cardiovasc Med. 2009 Jan;6(1):36-44
references.pmid: 19029991
references.citation: J Biol Chem. 2004 Mar 5;279(10):8886-94
references.pmid: 14684744
references.citation: Environ Sci Technol. 2002 Mar 15;36(6):1169-80
references.pmid: 11944666
references.citation: Toxicol Sci. 2011 Dec;124(2):472-86
references.pmid: 21914721