Structurally diverse steroids from an endophyte of Aspergillus tennesseensis 1022LEF attenuates LPS-induced inflammatory response through the cholinergic anti-inflammatory pathway

The emerging cholinergic anti-inflammatory pathway plays a key role in regulating inflammation. Steroids are known to possess remarkable anti-inflammatory activity. However, the links between steroids and the cholinergic anti-inflammatory pathway remain unidentified. In this study, eight steroids (1–8) featuring five different structural types were characterized from an endophytic fungus Aspergillus tennesseensis 1022LEF, and were subsequently evaluated for their potential role in regulating the cholinergic anti-inflammatory pathway. As a result, compound 8, with the best potency, showed remarkable anti-inflammatory activity at the nanomolar to low micromolar level. Further pharmacological study indicated that 8 notably increased α7nAchR expression and inhibited the activation of its down-stream signaling pathways. Collectively, the present study not only highlighted the potential correlation between steroids and the cholinergic anti-inflammatory pathway, but also identified 8 as a dual-functional modulator via directly inhibition to acetylcholinesterase as well as up-regulation of α7nAchR expression.