title: Autophagy upregulation promotes macrophages to escape mesoporous silica nanoparticle (MSN)-induced NF-κB-dependent inflammation.
abstract: BACKGROUND
  Our previous studies (Int J Nanomed 10:22, 2015) have indicated that a single large dose of mesoporous silica nanoparticles (MSNs) can induce severe and selective nephrotoxicity, which is closely related to inflammation mediated by the NF-κB pathway. However, the effect of MSNs on other organs and the interactions of nanomaterials with biological systems remain rudimentary.
  
  
  OBJECTIVE
  This study aimed to clarify the biological behaviour and influence of MSNs on macrophages.
  
  
  METHODS
  The mice received a single intraperitoneal injection of a suspension of 150, 300 of 600 mg/kg MSNs, and RAW 264.7 cells were treated with MSNs at various concentrations and times. Cell viability was determined by MTT assay and LDH release assay. The NF-κB pathway and the target proinflammatory cytokines IL-1β and TNF-α were determined by western blotting or ELISA. Autophagy is considered as an emerging mechanism of nanomaterials. So the autophagic ultrastructural analysis, the determination of Beclin-1 and LC3 expression, and the calculation of LC3II dots were employed to verify autophagy activation. In addition, RNA interference, autophagy agonist and inhibitor were used to explore the role of autophagy in inflammation.
  
  
  RESULTS
  The results indicated that MSNs are internalized into macrophages and induce cytotoxicity in a dose- and time-dependent manner. The NF-κB pathway, IL-1β and TNF-α were induced and released by MSNs. The levels of Beclin-1 and LC3II dots were obviously up-regulated by MSNs, which indicated that autophagy was induced in the MSN-treated cells. Moreover, the enhanced autophagy can attenuate the inflammation mediated by the NF-κB pathway, whereas the inhibition of autophagy can contribute to inflammation.
  
  
  CONCLUSIONS
  In summary, our results suggest that autophagy may be a possible protective factor in inflammation induced by MSNs in macrophages.
authors: Pharmaceutical Department, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, People's Republic of China.
authors: Chen
authors: C
authors: Xi
authors: School of Medicine, Yichun University, 576 XueFu Road, Yuanzhou District, 336000, Yichun, People's Republic of China. zj9032@126.com.
authors: Jie
authors: J
authors: Zhou
authors: Pharmaceutical Department, The First Affiliated Hospital of Zhengzhou University, 450052, Zhengzhou, People's Republic of China. du_shuzhang@126.com.
authors: Shuzhang
authors: S
authors: Du
authors: School of Medicine, Yichun University, 576 XueFu Road, Yuanzhou District, 336000, Yichun, People's Republic of China.
authors: Shaojun
authors: S
authors: Peng
mesh_terms: D000818:Animals; D001343:Autophagy / Q000276:immunology*; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D005260:Female; D007249:Inflammation / Q000276:immunology*; D053583:Interleukin-1beta / Q000276:immunology; D008099:Liver / Q000187:drug effects / Q000473:pathology / Q000648:ultrastructure; D008264:Macrophages / Q000187:drug effects* / Q000276:immunology; D008807:Mice, Inbred BALB C; D046529:Microscopy, Electron, Transmission; D016328:NF-kappa B / Q000276:immunology*; D053758:Nanoparticles / Q000633:toxicity*; D016062:Porosity; D012822:Silicon Dioxide / Q000633:toxicity*; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology; D015854:Up-Regulation
chemical_list: D053583:Interleukin-1beta; D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha; D012822:Silicon Dioxide
keywords: Autophagy; Inflammation; Macrophage; Mesoporous silica nanoparticles (MSNs); NF-κB