Figure 4.

NF-κB Pathway Is Involved in the Enhanced Proliferation of AEC2s after IL-1 or TNFα Stimulation

(A) Schematic of sample preparation for RNA-seq experiment.

(B) Heatmap of 165 genes whose expression was significantly different in IL-1β- or TNFα-treated AEC2s compared with controls.

(C and D) Top 10 pathway (C) and GO terms (D) enriched in the 165 differentially expressed genes shown in (B).

(E) Schematic diagram of IL-1 downstream signaling. Myd88 KO cells and IRAK4 inhibitor AS2444697 were used to disrupt the pathway.

(F) Representative images of organoids using Myd88 KO cells at day 15.

(G) Representative images for sections of lungs from wild-type (right panel) and Myd88 KO mice (left panel) at 10 dpi. White arrowheads indicate EdU⁺ proliferating AEC2s. Scale bar, 50 μm.

(H) Representative images of organoids treated with 0.1 ng/mL IL-1β or 10 μM IRAK4 inhibitor AS2444697 together with 0.1 ng/mL of IL-1β. All experiments were independently performed three times.

(I) Schematic model for the role of IL-1 and TNFα in inflammation-associated alveolar stem cell niche. We suggest that inflammatory cytokines IL-1 and TNFα released from inflamed area serve as a facultative “inflammation-associated niche,” resulting in the enhanced proliferation of AEC2s. Once AEC2s replicate, these cells give rise to AEC1s and contribute to lung repair.