3.8 Compound 270 affects various molecular mechanisms involved in the pathogenesis of acute kidney and lung injury challenged with intraperitoneal injection of LPS
NF-κB signaling pathways activated by LPS play vital roles in inflammation, oxidative stress, endoplasmic reticulum (ER) stress and autophagy, all these participate in the development of LPS-induced acute kidney and lung injury (Muriach et al. , 2014). Myeloperoxidase (MPO) is a specific indicator of neutrophils and macrophages infiltration and indirectly reflects the severity of inflammation in injury tissues (Huang et al. , 2016). Our results pointed that MPO activity of kidney and lung tissues was higher in the LPS-treated group compared with the Veh group, and pretreatment with 270 dose dependently reduced mice renal (Figure 8A) and lung (Figure 8E) MPO activity compared with the LPS group.
Malondialdehyde (MDA) is considered to be a marker reflecting the level of oxidative stress, and its formation could aggravate damage to cell membranes (Niu et al. , 2019). The MDA content of mice in kidney and lung tissues was significantly increased after 24 h LPS injection, while 270 pretreatment inhibited the enhancement of MDA content in renal (Figure 8B) and lung (Figure 8F) tissues induced by LPS. To further elucidate the protective role of 270 in LPS-induced AKI and ALI, the protein levels of ER stress markers (BiP and CHOP) and autophagy-related factors (LC3A and p62) were measured via western blotting. Our results showed that LPS obviously promoted the expression of BiP and CHOP proteins in mice kidney and lung tissues, and the up-regulation of the BiP and CHOP proteins in kidney (Figure 8C,D) and lung (Figure 8G,H) tissues was diminished by 270 administration, indicating that 270 could suppress the activated ER stress. Besides, we found LPS stimulation elevated the protein levels of LC3A and p62 in mice kidney and lung tissues, and the effect of LPS on these proteins in renal (Figure 8C,D) and lung tissues (Figure 8G,H) was normalized by 270 administration, suggesting that 270 could reverse the inhibition effect of LPS on autophagy.