Long-term administration of pirfenidone improves cardiac function in mdx mice

Duchenne muscular dystrophy, an X-linked recessive neuromuscular disorder due to lack of the protein dystrophin, manifests as progressive muscle degeneration and cardiomyopathy with increased fibrosis. The exact mechanisms involved in fibrosis are unknown, but a cytokine, transforming growth factor-beta (TGF-beta), is a likely mediator. This study tested whether the TGF-beta antagonist, pirfenidone, could reduce cardiac fibrosis. Eight-month-old mdx mice were treated for 7 months with 0.4%, 0.8%, and 1.2% pirfenidone in drinking water; untreated water was given to control mdx and C57 mice. Mice treated with 0.8% and 1.2% pirfendone had lowered cardiac TGF-beta mRNA and improved in vitro cardiac contractility (P < 0.05) to levels consistent with C57 mice, yet without a change in cardiac stiffness or fibrosis. These results show that the TGF-beta antagonist, pirfenidone, can improve cardiac function in mdx mice, potentially providing a new avenue for developing cardiac therapies for patients with Duchenne muscular dystrophy.