FIGURE 6.

A proposed corticosteroid re‐sensitization mechanism of andrographolide in COPD. Cigarette smoke down‐regulates Nrf2 level, up‐regulates c‐Jun expression, and stimulates PI3K/Akt/p706K signalling pathway, which leads to reduction of HDAC2 level, resulting in corticosteroid resistance in COPD. Andrographolide up‐regulates Nrf2 expression, reduces c‐Jun level, and blocks PI3K/Akt/p70S6K signalling pathway, resulting in restoration of HDAC2 level in COPD. HDAC2: histone deacetylase‐2; Nrf2: nuclear factor erythroid 2‐related factor 2; PI3K: phosphoinositide‐3‐kinase; p70S6K: p70 S6 kinase