n-3 Polyunsaturated fatty acids alter expression of fibrotic and hypertrophic genes in a dog model of atrial cardiomyopathy.
BACKGROUND
We previously showed that omega-3 polyunsaturated fatty acids (PUFAs) reduce vulnerability to atrial fibrillation (AF). The mechanisms underlying this effect are unknown.


OBJECTIVE
The purpose of this study was to use a genome-wide approach to identify gene expression profiles involved in a new model of AF vulnerability and to determine whether they were altered by PUFA therapy.


METHODS
Thirty-six dogs were randomized evenly into three groups. Two groups were paced using simultaneous atrioventricular pacing (SAVP) at 220 bpm for 14 days to induce atrial enlargement, fibrosis, and susceptibility to AF. One group was supplemented with oral PUFAs (850 mg/day) for 21 days, commencing 7 days before the start of pacing (SAVP-PUFAs). The second group received no PUFAs (SAVP-No PUFAs). The remaining dogs were unpaced, unsupplemented controls (CTRL). Atrial tissue was sampled at the end of the protocol. Gene expression was analyzed in four dogs randomly selected from each group (n = 12) via microarray. Results were confirmed with quantitative real-time polymerase chain reaction (RT-PCR) and histology on all 36 dogs.


RESULTS
Microarray or quantitative RT-PCR results showed that SAVP-No PUFAs dogs had significantly increased mRNA levels of protein kinase B (Akt), epidermal growth factor (EGF), JAM3, myosin heavy chain alpha (MHCalpha), and CD99 and significantly decreased levels of Smad6 compared with CTRL dogs. Quantitative RT-PCR showed that PUFA supplementation was associated with significant down-regulation of Akt, EGF, JAM3, MHCalpha, and CD99 levels compared with SAVP-No PUFAs dogs.


CONCLUSIONS
The effect of PUFAs on these fibrosis, hypertrophy, and inflammation related genes suggests that, in this model, PUFA-mediated prevention of AF may be due to attenuation of adverse remodeling at the genetic level in response to mechanical stress.
Keenan Research Centre in the Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada.
Andrew
A
Ramadeen
Gabriel
G
Laurent
Claudia C
CC
dos Santos
Xudong
X
Hu
Kim A
KA
Connelly
Bruce J
BJ
Holub
Iqwal
I
Mangat
Paul
P
Dorian
D000818:Animals; D001281:Atrial Fibrillation / Q000517:prevention & control*; D016275:Atrial Function / Q000187:drug effects*; D009202:Cardiomyopathies / Q000235:genetics*; D002317:Cardiovascular Agents / Q000494:pharmacology* / Q000627:therapeutic use; D004195:Disease Models, Animal; D004285:Dogs; D015525:Fatty Acids, Omega-3 / Q000494:pharmacology* / Q000627:therapeutic use; D005355:Fibrosis / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D006325:Heart Atria / Q000187:drug effects* / Q000503:physiopathology; D006984:Hypertrophy / Q000235:genetics; D013314:Stress, Mechanical
D002317:Cardiovascular Agents; D015525:Fatty Acids, Omega-3