Decreased expression of the NF-κB family member RelB in lung fibroblasts from Smokers with and without COPD potentiates cigarette smoke-induced COX-2 expression.
BACKGROUND
Heightened inflammation, including expression of COX-2, is associated with COPD pathogenesis. RelB is an NF-κB family member that attenuates COX-2 in response to cigarette smoke by a mechanism that may involve the miRNA miR-146a. There is no information on the expression of RelB in COPD or if RelB prevents COX-2 expression through miR-146a.


METHODS
RelB, Cox-2 and miR-146a levels were evaluated in lung fibroblasts and blood samples derived from non-smokers (Normal) and smokers (At Risk) with and without COPD by qRT-PCR. RelB and COX-2 protein levels were evaluated by western blot. Human lung fibroblasts from Normal subjects and smokers with and without COPD, along with RelB knock-down (siRNA) in Normal cells, were exposed to cigarette smoke extract (CSE) in vitro and COX-2 mRNA/protein and miR-146a levels assessed.


RESULTS
Basal expression of RelB mRNA and protein were significantly lower in lung cells derived from smokers with and without COPD, the latter of which expressed more Cox-2 mRNA and protein in response to CSE. Knock-down of RelB in Normal fibroblasts increased Cox-2 mRNA and protein induction by CSE. Basal miR-146a levels were not different between the three groups, and only Normal fibroblasts increased miR-146a expression in response to smoke. There was a positive correlation between systemic RelB and Cox-2 mRNA levels and circulating miR-146a levels were higher only in GOLD stage I subjects.


CONCLUSIONS
Our data indicate that RelB attenuates COX-2 expression in lung structural cells, such that loss of pulmonary RelB may be an important determinant in the aberrant, heightened inflammation associated with COPD pathogenesis.
Department of Medicine, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. sheridanja88@gmail.com.
Jared A
JA
Sheridan
Department of Medicine, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. michela.zago@mail.mcgill.ca.
Michela
M
Zago
Department of Medicine, McMaster University, Hamilton, ON, Canada. parames@mcmaster.ca.
Parameswaran
P
Nair
Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University, Montreal, QC, Canada. pei.li@mail.mcgill.ca.
Pei Z
PZ
Li
Respiratory Epidemiology and Clinical Research Unit, Montreal Chest Institute, McGill University, Montreal, QC, Canada. jean.bourbeau@mcgill.ca.
Jean
J
Bourbeau
The UBC James Hogg Research Centre, University of British Columbia, Vancouver, BC, Canada. wan.tan@hli.ubc.ca.
Wan C
WC
Tan
Department of Medicine, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. qutayba.hamid@mcgill.ca.|Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. qutayba.hamid@mcgill.ca.
Qutayba
Q
Hamid
Department of Medicine, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. david.h.eidelman@mcgill.ca.|Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. david.h.eidelman@mcgill.ca.
David H
DH
Eidelman
Department of Epidemiology and Biostatistics, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. andrea.benedetti@mcgill.ca.
Andrea L
AL
Benedetti
Department of Medicine, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. carolyn.baglole@mcgill.ca.|Research Institute of the McGill University Health Centre, 1001 Decarie Blvd, Montreal, QC, H4A 3J1, Canada. carolyn.baglole@mcgill.ca.
Carolyn J
CJ
Baglole
D000368:Aged; D002478:Cells, Cultured; D003430:Cross-Sectional Studies; D051546:Cyclooxygenase 2 / Q000096:biosynthesis*; D005260:Female; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008168:Lung / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D016328:NF-kappa B / Q000096:biosynthesis; D029424:Pulmonary Disease, Chronic Obstructive / Q000453:epidemiology / Q000378:metabolism*; D012906:Smoke / Q000009:adverse effects; D012907:Smoking / Q000453:epidemiology / Q000378:metabolism*; D014026:Nicotiana / Q000633:toxicity; D051841:Transcription Factor RelB / Q000096:biosynthesis*
D016328:NF-kappa B; C497593:RELB protein, human; D012906:Smoke; D051841:Transcription Factor RelB; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human