A novel nordihydroguaiaretic acid analog, compound 3a, alleviates acute lung injury by exerting antiapoptotic and antiinflammatory effects

Abstract

Acute lung injury (ALI) is a continuum of pulmonary changes caused by various lung insults. Previously, we synthesized a series of nordihydroguaiaretic acid analogs; of these, compound 3a exhibited excellent antioxidant capacity in a murine model of middle cerebral artery occlusion. However, it remains unclear whether compound 3a can modulate lipopolysaccharide (LPS)-induced ALI. ALI was induced via tracheal LPS administration, and the pathological changes were assessed. The level of inflammation was verified by immunofluorescence and immunohistochemical analyses. Apoptosis was measured by terminal deoxynucleotidyl transferase dUTP nick-end labeling assays and Western blotting. Changes in the levels of mitogen-activated protein kinase (MAPK)/nuclear factor-κB (NF-κB) pathway proteins were assessed by immunofluorescence assays and Western blotting. In vitro, RAW 264.7 cells were treated with compound 3a prior to LPS challenge, and the intracellular level of inflammation was assessed by quantitative PCR (qPCR). Relevant proteins were detected via immunofluorescence assays and Western blotting. Mice developed extensive lung inflammation by 24 h after LPS challenge. Histological examination revealed signs typical of ALI. Preadministration of compound 3a markedly ameliorated the histopathological changes and reduced fluid exudation into the alveolar space. Compound 3a also greatly reduced the levels of inflammation and apoptosis both in vivo and in vitro. Moreover, compound 3a markedly reduced phosphorylation of MAPK/NF-κB pathway-related proteins and p65 translocation, consistent with the in vitro observations. In summary, administration of compound 3a prior to LPS suppressed ALI via inhibition of the MAPK/NF-κB pathway.