Negative Feedback of the cAMP/PKA Pathway Regulates the Effects of Endoplasmic Reticulum Stress-Induced NLRP3 Inflammasome Activation on Type II Alveolar Epithelial Cell Pyroptosis as a Novel Mechanism of BLM-Induced Pulmonary Fibrosis

Figure 4

Endoplasmic reticulum stress promoted NLRP3 inflammasome activation and pyroptosis in type II alveolar epithelial cells. A549 cell lines were pretreated 4PBA (5 mM) for 1 h or NLRP3 expression was knocked down by siRNA transfection before exposure to tunicamycin (1 μg/mL) for 24 h. (a–e) Protein levels of the ER stress markers Grp94 and CHOP and the NLRP3 inflammasome-related proteins NLRP3, ASC, cleaved caspase-1, cleaved IL1β, and N-GSDMD were detected by Western blot analysis. (f, g) Colocalization of Grp94/NLRP3 and CHOP/NLRP3 was detected by immunofluorescence staining. (h) LDH release assay of cell viability. (i) Cell viability was assessed by CCK8 assay. vs. control group, vs. tunicamycin group, (j) LDH release assay of cell viability, (k) cell viability was assessed by CCK8 assay. n.s.: not significant vs. control group, vs. tunicamycin group.

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