Calcium binding protein S100A4 inhibitor Niclosamide regulates inflammatory response of bronchial epithelial cells.

Objective: To investigate potential mechanisms of Niclosamide, a calcium-binding protein S100A4 inhibitor, in regulating inflammatory response of bronchial epithelial cells. Methods: Human bronchial epithelial cells BEAS-2B were cultured in vitro and stimulated by LPS or Niclosamide-pretreatment. Inflammatory cytokines and potential signaling molecules expressions were determined by RT-qPCR and Western blot. Intracellular ROS level was quantified by fluorescent probe. Results: Increased ROS level was observed in LPS-stimulated and Niclosamide-pretreatment cells (P<0.05). Compared with control group, mRNA and protein expressions of S100A4 were increased (P<0.05), TLR4/STAT3, MAPK1/3/SIRT1, NF-κB/IKKp/p65 mRNA expressions were increased (P<0.05), inflammatory cytokines IL-1(3 and IL-6, tight junction Occludin and ZO-1 mRNA expressions were increased after LPS-treatment (P<0.05), whereas these genetic expressions were downregulated by Niclosamide-pretreatment (P<0.05), except for TLR4/MAPK1 and NF-KB/IKK(Vp65 (P>0.05). Western blot showed that compared with control group, LPS-stimulation promoted protein expressions of S100A4, STAT3, MAPK3/SIRT1, IL-1β and TNF-α (P<0.05), while downregulated protein expression of Occludin. Compared with LPS group, niclosamide-pretreatment downregulated protein expressions of S100A4, STAT3, MAPK3/ SIRT1, IL-1β and TNF-α (P<0.05), while restored protein expression of Occludin (P<0.05). Conclusion: Calcium-binding protein S100A4 inhibitor Niclosamide can alleviate S100A4 expression and inflammatory response of bronchial epithelial cells, which is potentially related to STAT3 or MAPK3/S1RT1 signaling. [ABSTRACT FROM AUTHOR]