Costunolide alleviates HKSA-induced acute lung injury via inhibition of macrophage activation.

Staphylococcus aureus (S. aureus) infection leads to a severe inflammatory response and causes acute lung injury (ALI), eventually threatening human life. Therefore, it is of importance to find an agent to inhibit inflammation and reduce ALI. Here, we found that costunolide, a sesquiterpene lactone, displays anti-inflammatory effects and ameliorates heat-killed S. aureus (HKSA)-induced pneumonia. Costunolide treatment attenuated HKSA-induced murine ALI in which pulmonary neutrophil infiltration was inhibited, lung edema was decreased, and the production of pro-inflammatory cytokines was significantly reduced. In addition, costunolide dose-dependently inhibited the generation of IL-6, TNF-α, IL-1ß, and keratinocyte-derived cytokine (KC), as well as the expression of iNOS, in HKSA-induced macrophages. Furthermore, costunolide attenuated the phosphorylation of p38 MAPK and cAMP response element-binding protein (CREB). Collectively, our findings suggested that costunolide is a promising agent for alleviating bacterial-induced ALI via the inhibition of the MAPK signaling pathways.

Isoalantolactone suppresses LPS-induced inflammation by inhibiting TRAF6 ubiquitination and alleviates acute lung injury.

Isoalantolactone (IAL) is a sesquiterpene lactone extracted from roots of Inula helenium L and has shown anti-inflammatory effects. In this study we investigated the therapeutic effects of IAL on acute lung injury (ALI) and elucidated the mechanisms underlying its anti-inflammation potential in vitro and in vivo. Treatment with lipopolysaccharide (LPS, 100 ng/mL) drastically stimulated production of inflammatory mediators such as NO, TNF-α, IL-1ß, and IL-6 in mouse bone marrow-derived macrophages (BMDMs), which was dose-dependently suppressed by pretreatment with IAL (2.5, 5, 10, 20 µM). We further revealed that IAL suppressed LPS-induced NF-κB, ERK, and Akt activation. Moreover, the downregulation of non-degradable K63-linked polyubiquitination of TRAF6, an upstream transcription factor of NF-κB, contributed to the anti-inflammatory effects of IAL. ALI was induced in mice by intratracheal injection of LPS (5 mg/kg). Administration of IAL (20 mg/kg, i.p.) significantly suppressed pulmonary pathological changes, neutrophil infiltration, pulmonary permeability, and pro-inflammatory cytokine expression. Our results demonstrate that IAL is a potential therapeutic reagent against inflammation and ALI.