IL-33 facilitates endoplasmic reticulum stress and pyroptosis in LPS-stimulated ARDS model in vitro.

BACKGROUND

Inflammatory activation of pulmonary microvascular endothelial cells (PMVECs) initiated by endoplasmic reticulum stress (ERS) contributes to acute respiratory distress syndrome (ARDS). Interleukin 33 (IL-33) has pro-inflammatory and transcriptional regulatory effects. Therefore, this study intends to investigate the effect of IL-33 on ERS and pyroptosis in the hPMVEC.

METHODS

The hPMVEC-associated ARDS cell model was induced with lipopolysaccharide (LPS) and treated with 4-PBA (ERS inhibitor), thapsigargin (ERS activator), or IL-33 neutralizing antibody. Western blot and IF staining were performed to analyze the expression of cell-cell junction-associated (Cx37, Cx40, Cx43, Occludin, and Zo-1), ERS-associated (ATF6, IRE1a, and p-Erk), and pyroptosis-associated (NLRP3, IL-1β, and IL-18) proteins. Bioinformatics identified differential expression of IL-33 in ARDS-related datasets and targets of thapsigargin.

RESULTS

IL-33 was highly expressed in serum of ARDS patients and in ARDS cohorts from multiple GEO datasets (GSE237260, GSE216635, GSE89953, GSE263867, and GSE5883), and was significantly correlated with clinical features. 4-PBA decreased permeability and IL-33 levels, and increased Cx37, Cx40 and Cx43 levels in the ARDS cell model. IL-33 neutralizing antibody effectively augmented the levels of Cx43 and Zo-1, and diminished the levels of ATF6, IRE1a, p-Erk, NLRP3, IL-1β, IL-18, ROS, and Ca2 +. The therapeutic effect of IL-33 neutralizing antibodies was reverted by thapsigargin. Moreover, the Swiss Target Prediction and Super-PRED databases obtained 140 and 122 thapsigargin targets, which had 14 intersections. These intersections were associated with immunity, inflammation, apoptosis, pyroptosis, and Ca2+ homeostasis. Notably, CASP8 and PTGS2 interacted with IL-33 in these intersections.

CONCLUSION

IL-33 promotes ERS and pyroptosis, thereby contributing to barrier damage in ARDS cell models. IL-33 is a promising therapeutic target for ARDS.