PDGFA and interstitial lung disease: AEC2 sorted from BLM-ILD lungs in the early phase expressed various inflammatory or profibrotic genes associated with SASP, including Il6, Tnfa, Ccl2, Serpin1, Tgfb, and Pdgfa. We speculated that these inflammatory mediators contributed to the initiation and progression of the disease: IL-6, PAI-1 encoded by Serpin1, and TGFβ promoted senescent cells and/or amplified senescence; CCL2 attracted circulating Ly6C+ monocytes into the lungs; and infiltrated Ly6C+ monocytes were activated by TNFα and differentiated into MHCII-expressing interstitial macrophages.