CSF1 and pulmonary fibrosis: Monocyte‐derived macrophages drive lung fibrosis via expressing various profibrotic genes that differ from tissue‐resident alveolar macrophages.[28] In addition, monocyte‐derived macrophages highly expressing CSF1/CSF1R may constitute an autocrine M‐CSF/M‐CSFR loop to support their population and form a profibrotic circuit.[29] Using anti‐CSF1R antibodies to specifically deplete interstitial macrophages (monocyte‐derived) can ameliorate lung fibrosis.[30] Indeed, compared to alveolar macrophages (AMs), tissue‐infiltrating macrophages (IMs) have higher levels of CSF1R protein.