Putative mechanisms of macrophage participation in apoptosis in idiopathic pulmonary fibrosis
| Impaired removal of apoptotic cell remnants (efferocytosis) |
| Induction of normal macrophage cell death by apoptotic macrophages |
| Induction of AEC apoptosis by cytokines and growth factor secreted by macrophages (e.g. TGF-β1 and TNF-α) |
| Inhibition of myofibroblast apoptosis through the release of insulin-like growth factor |
AEC: alveolar epithelial cell; TGF: transforming growth factor; TNF: tumour necrosis factor.