YPL-001 Shows Various Beneficial Effects against Cigarette Smoke Extract-Induced Emphysema Formation: Anti-Inflammatory, Anti-Oxidative, and Anti-Apoptotic Effects

Inflammation, oxidative stress, and apoptosis are thought to be important causes of chronic obstructive pulmonary disease (COPD). We investigated the effect of YPL-001 (under phase 2a study, ClinicalTrials.gov identifier NCT02272634), a drug derived from Pseudolysimachion rotundum var. subintegrum, on cigarette smoke extract (CSE)-induced inflammation, the anti-oxidative pathway, and apoptosis in human lung epithelial cells and on CSE-induced emphysema in mice. YPL-001 suppressed CSE-induced expression of IL8 mRNA and protein. This was due to the reduction in NF-κB transcriptional activity by YPL-001, which resulted from the blockade of acetylation of the NF-κB subunit p65 (Lys310). Histone deacetylases (HDACs) prevent gene transcription by condensing the DNA structure and affecting NF-κB nuclear binding. YPL-001 alone increased HDAC2 activity and enhanced CSE-induced activation of HDAC2. YPL-001-induced suppression of NF-κB transcriptional activity might be caused by increased HDAC2 activity. YPL-001 increased nuclear factor (erythroid-derived 2)-like 2 (Nrf2) expression via both degradation of its inhibitory protein, Kelch-like ECH-associated protein 1, and an increase in de novo protein synthesis. YPL-001 increased the DNA binding activity of Nrf2. Consequently, YPL-001 upregulated the expression of Nrf2-targeted anti-oxidant genes such as NAD(P)H quinone dehydrogenase 1 and heme oxygenase 1. Moreover, YPL-001 significantly suppressed CSE-induced apoptotic cell death. In vivo study showed that CSE-induced emphysematous changes, neutrophilic inflammation, protein leakage into bronchoalveolar space, and lung cell apoptosis in mice were suppressed by YPL-001 treatment. Taken together, these results suggest that YPL-001 is a good therapeutic candidate for the treatment of COPD by blocking inflammation and apoptosis and activating the anti-oxidative pathway.