Aortic carboxypeptidase-like protein is expressed in fibrotic human lung and its absence protects against bleomycin-induced lung fibrosis.

The pathological hallmarks of idiopathic pulmonary fibrosis include proliferating fibroblasts and myofibroblasts, as well as excessive collagen matrix deposition. In addition, both myofibroblast contraction and remodeling of the collagen-rich matrix contribute to the abnormal structure and function of the fibrotic lung. Little is known, however, about collagen-associated proteins that promote fibroblast and myofibroblast retention, as well as the proliferation of these cells on the extracellular matrix. In this study, we demonstrate that aortic carboxypeptidase-like protein (ACLP), a collagen-associated protein with a discoidin-like domain, is expressed at high levels in human fibrotic lung tissue and human fibroblasts, and that its expression increases markedly in the lungs of bleomycin-injured mice. Importantly, ACLP-deficient mice accumulated significantly fewer myofibroblasts and less collagen in the lung after bleomycin injury, as compared with wild-type controls, despite equivalent levels of bleomycin-induced inflammation. ACLP that is secreted by lung fibroblasts was retained on fibrillar collagen, and ACLP-deficient lung fibroblasts that were cultured on collagen exhibited changes in cell spreading, proliferation, and contraction of the collagen matrix. Finally, the addition of recombinant discoidin-like domain of ACLP to cultured ACLP-deficient lung fibroblasts restored cell spreading and increased the contraction of collagen gels. Therefore, both ACLP and its discoidin-like domain may be novel targets for anti-myofibroblast-based therapies for the treatment of pulmonary fibrosis.

PPARδ modulation rescues mitochondrial fatty acid oxidation defects in the mdx model of muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a recessive, fatal X-linked disease that is characterized by progressive skeletal muscle wasting due to the absence of dystrophin, which is an a essential protein that bridges the inner cytoskeleton and extra-cellular matrix. This study set out to characterize the mitochondria in primary muscle satellite cell derived myoblasts from mdx mice and wild type control mice. Compared to wild type derived cells the mdx derived cells have reduced mitochondrial bioenergetics and have fewer mitochondria. Here, we demonstrate that a novel PPARδ modulator improves mitochondrial function in the mdx mice, which supports that modulating PPARδ may be therapeutically beneficial in DMD patients.