Effects of efferocytosis on fibrosis

Abstract

Billions of cells die every day to maintain homeostasis, and dying cells including apoptotic cells are removed rapidly by phagocytes. This process is called as efferocytosis. Efferocytosis is performed by macrophages and dendritic cells which are professional phagocytes or by fibroblasts, epithelial cells and endothelial cells which are non-professional phagocytes. Efferocytosis contributes to tissue homeostasis by removing apoptotic cells and promoting cell proliferation. Fibrosis is pathological tissue repair accumulating excessive extracellular matrix (ECM) after tissue is injured and thus apoptotic cells are generated. Based on the link of fibrosis and efferocytosis to dying cells, this study was conducted to test the effects of efferocytosis on fibrosis. In this study, mouse lung and ear fibroblasts were used as phagocytes, to validate the effects of efferocytosis on their fibrigenesis. I found that lung and ear fibroblasts derived from wild-type (WT) mice were capable of efferocytosis but fibrogenic markers such as Collagen type Ⅰ and α-sma were unaltered in the phagocytes. Additionally, induction of fibrosis by transforming growth factor-β1 (TGF-β1) was unaffected by efferocytosis. Taken together, mouse lung and ear fibroblasts are able to phagocytose apoptotic cells, but efferocytosis by the fibroblasts is unlikely affect fibrogenesis of the fibroblasts.