Pioglitazone, a peroxisome proliferator-activated receptor gamma activator, ameliorates experimental autoimmune myocarditis by modulating Th1/Th2 balance.
OBJECTIVE
The aim of this study is to investigate the effect of Peroxisome proliferator-activated receptor gamma (PPAR gamma) ligand on experimental autoimmune myocarditis (EAM).


BACKGROUND
Rat EAM model resembles the giant cell myocarditis in human. Recent studies have suggested that Th1 cytokines are involved in the initiation and progression of EAM, whereas Th2 cytokines are associated with the remission. PPAR gamma, which is a member of nuclear hormone receptor superfamily, has been known to affect not only glucose homeostasis but also immune responses, by regulating the Th1/Th2 balance.


METHODS
Lewis rats were immunized with cardiac myosin and divided into three groups: Group N, normal control rats (n = 16); Group E, EAM rats (n = 17); and Group P, EAM rats treated with a PPAR gamma activator pioglitazone (n = 20).


RESULTS
Cardiac dysfunction and remodeling were inhibited in Group P compared to Group E. Heart weight/body weight ratio and the degree of inflammation and fibrosis were significantly lower in Group P than in Group E. The mRNA levels of macrophage inflammatory protein-1alpha (MIP-1alpha), which plays an important role in the recruitment of inflammatory cells in the early stage of EAM, were upregulated in the heart of Group E, but not in the heart of Group P. Furthermore, the treatment with pioglitazone decreased the expression levels of proinflamatory cytokine (TNF alpha and IL-1beta) genes and Th1 cytokine (IFN-gamma) genes, and increased the expression levels of Th2 cytokine (IL-4) gene.


CONCLUSIONS
PPAR gamma ligands may have beneficial effects on myocarditis by inhibiting MIP-1alpha expression and modulating the Th1/Th2 balance.
Hasegawa
Hiroshi
H
Department of Cardiovascular Science and Medicine, Chiba University Graduate School of Medicine (M4), 1-8-1 Inohana, Chiba 260-8670, Japan.
Takano
Hiroyuki
H
Zou
Yunzeng
Y
Qin
Yingjie
Y
Hizukuri
Kaoru
K
Odaka
Kenichi
K
Toyozaki
Tetsuya
T
Komuro
Issei
I
D000818:Animals; D001327:Autoimmune Diseases / Q000276:immunology / Q000473:pathology* / Q000503:physiopathology; D001835:Body Weight / Q000187:drug effects; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D004195:Disease Models, Animal; D005260:Female; D006439:Hemodynamics; D009205:Myocarditis / Q000276:immunology / Q000378:metabolism / Q000473:pathology* / Q000503:physiopathology; D009929:Organ Size / Q000187:drug effects; D047495:PPAR gamma / Q000819:agonists* / Q000378:metabolism; D000077205:Pioglitazone; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D018417:Th1 Cells / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism*; D018418:Th2 Cells / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D045162:Thiazolidinediones / Q000494:pharmacology*
D016207:Cytokines; D047495:PPAR gamma; D012333:RNA, Messenger; D045162:Thiazolidinediones; D000077205:Pioglitazone