The disease known as Duchenne Muscular Dystrophy (MD) progresses through a phase where proteins, such as dystrophin, which are critical for muscle function, are lost, leading to contraction-related tears of muscle fibers and cellular damage. This, in turn, leads to movement of calcium into muscle tissue. The increasing calcium concentration in the muscle cells stimulates a protein, known as cyclophilin D to allow the calcium into the mitochondria, which, unfortunately, has the effect, ultimately, of causing these cellular power plants to swell and rupture, leading to muscle cell death. Mice prone to muscular dystrophy, but lacking cyclophilin D, interestingly, do not exhibit the same traits and are near normal. Might drugs that inhibit cyclophilin D be therapeutic for muscular dystrophy? That’s a question scientists have been wanting to know the answer to and now, according to Dr. Jeff Molkentin, a researcher in the Division of Molecular Cardiovascular Biology at Cincinnati Children’s Hospital, there is reason to believe it may. Writing in the online, March 16 issue of the journal Nature Medicine, Dr. Molkentin reports that an anti-viral drug, known as Debio-025, which is a cyclophilin inhibitor, similarly reduces mitochondrial swelling and necrotic disease manifestations in mice that are genetically pre-disposed to developing muscular dystrophy. Debio-025 is best known as an anti-viral treatment for Hepatitis C and is also used when patients are coinfected with HIV. Hepatitis C virus is believed to derive replication advantages from cyclophilins in the liver, so treatment with Debio-025 battles that virus, as well.