Aqueous Extract of Descuraniae Semen Attenuates Lipopolysaccharide-Induced Inflammation and Apoptosis by Regulating the Proteasomal Degradation and IRE1a-Dependent Unfolded Protein Response in A549 Cells

Background: Lipopolysaccharide (LPS)-induced acute lung injury (ALI) induces endoplasmic reticulum stress, unfolded protein response (UPR), apoptosis, and inflammation. Inositol-requiring enzyme 1 (IRE1)-alpha is important for adaptive and apoptotic UPR determination during ER stress. The aqueous extract of Descuraniae Semen (AEDS) is reported to be a safe and effective herb for the treatment of pulmonary edema as it shows anti-inflammatory activities. Methods: We investigated the effects of AEDS on LPS-induced ALI in A549 cells with respect to the regulation of IRE1 alpha-dependent UPR, proteasomal degradation, mitochondrial membrane potential (MtMP), inflammation, and apoptosis. Results: AEDS attenuated ER stress by regulating the proteasomal degradation. LPS induced ER stress [binding immunoglobulin protein (BiP), phosphorylated IRE1 alpha, sliced X-box binding protein 1 [XBP1s], phosphorylated cJUN NH2-terminal kinase (pJNK), B-cell lymphoma (Bcl)-2-associated X (Bax), Bcl-2], inflammation (nucleus factor-kappa B (NF-kappa B) p65 nuclear translocation, nucleus NF-kappa B, pro-inflammatory cytokines] and apoptosis [C/EBP homologous protein (CHOP), cytochrome c, caspase-8, and caspase-6, and TUNEL] were significantly attenuated by AEDS treatment in A549 cells. AEDS prevents LPS-induced decreased expression of MtMP in A549 cells. Conclusions: AEDS attenuated LPS-induced inflammation and apoptosis by regulating proteasomal degradation, promoting IRE1 alpha-dependent adaptive UPR, and inhibiting IRE1 alpha-dependent apoptotic UPR. Moreover, IRE1 alpha-dependent UPR plays a pivotal role in the mechanisms of LPS-induced ALI. Based on these findings, AEDS is suggested as a potential therapeutic option for treating patients with ALI.