Investigation into Mechanisms NLRP3 Activation by Nickel Associated Multi-Walled Carbon Nanoparticles

Certain engineered nanomaterials (ENM) have been shown to cause pathological changes in animal models raising concern that human health effects will emerge with increasing use and exposure. In vitro toxicity testing has not revealed an appropriate model system or assays that are reliable in predicting in vivo outcomes. Consequently, a predictive model based on physical and surface properties has not been established to aid in protecting human health.  We have shown that there is good correlation between the ability of nickel associated MWCNT (Ni-MWCNT) to activate the NLRP3 inflammasome (NLRP3) in vitro using primary alveolar macrophages (AM) or THP-1 cells with lung inflammation and pathology.  Furthermore, in vitro activation of the NLRP3 appears to be a better predictor of lung inflammation than in vitro toxicity.  Consequently, certain but not all ENM can function as “danger signals” to activate NLRP3.  The basis for the distinction is most likely associated with the ability of ENM to be phagocytosed into lysosomes and/or ability to disrupt lysosomes causing cathepsin B release.  We hypothesize that the in vivo inflammatory potential of ENM correlates well with lysosomal disrupting activity and NLRP3 activation.  Furthermore, the inflammatory potential of ENM will be dependent on the amount of nickel associated to the MWCNT Therefore, our aims are: 1. Determine the relationship between NLRP3 inflammasome activity in primary murine alveolar macrophages (AM) and lung pathology in mice following exposure to Ni-MWCNT. 2. Determine the importance of Ni-MWCNT surface properties (amount of Nickel and surface charge) to cause cytotoxicity and degree of activation of the NLRP3 inflammasome using THP-1 cells. Finally, to establish that internalization of MWCNT-Ni followed by lysosomal membrane disruption and Cathepsin   B release is the initiating event in activation of the NLRP3 inflammasome.  Thus, information from this study will be important in determining characteristics of safe ENM and establish mechanisms of action.

Impact Statement:

These studies will establish the potential of nanomaterials to disrupt lysosomal membranes and activate the NRLP3 inflammasome to cause in vivo inflammation and pathology. Furthermore that the assays performed in the proposal may serve as tools for high throughput screening of ENM.