Complement 3 deficiency and oral prednisolone improve strength and prolong survival of laminin α2-deficient mice

Abstract Complement deposition and macrophages are common in biopsies of children with muscular dystrophy. While the presumed roles of complement and macrophages have been those of scavenger to remove and clear necrotic fibers, there is some evidence that they play a primary role in the pathogenesis of these diseases. Here, we explore the role of complement in the pathogenesis of the most severe animal model of congenital dystrophy, the dy −/− mouse, which is laminin α2-deficient. We generated animals deficient in both C3 and laminin α2. C3 is the third component of the complement cascade and is required for activation of either the classical or alternative pathways. Thirty-three percent of the dy −/−: C3 + mice ( n =59) died before 24 weeks while only 14% of the dy −/−: C3 −/− ( n =29) mice died ( p =0.04). Absolute forepaw strength was 25–30% greater for the dy −/−: C3 −/− mice up to 20 weeks of age ( p C3 −/− mice being stronger up to 20 weeks ( p dy −/− mice ( C3 −/− or C3 +) was 90% ( p =0.04). This work shows that complement insufficiency and weekly prednisone prolong survival and improve strength of the laminin α2-deficient mouse. This work suggests that the complement system may contribute directly to the pathogenesis of this form of dystrophy. Because complement activity may be modified pharmacologically, this work may have implications for treatment of children with congenital muscular dystrophy secondary to laminin α2 deficiency.