Nanoparticle-induced neuronal toxicity across placental barriers is mediated by autophagy and dependent on astrocytes


The potential for maternal nanoparticle (NP) exposures to cause developmental toxicity in the fetus without the direct passage of NPs has previously been shown, but the mechanism remained elusive. We now demonstrate that exposure of cobalt and chromium NPs to BeWo cell barriers, an in vitro model of the human placenta, triggers impairment of the autophagic flux and release of interleukin-6. This contributes to the altered differentiation of human neural progenitor cells and DNA damage in the derived neurons and astrocytes. Crucially, neuronal DNA damage is mediated by astrocytes. Inhibiting the autophagic degradation in the BeWo barrier by overexpression of the dominant-negative human ATG4BC74A significantly reduces the levels of DNA damage in astrocytes. In vivo, indirect NP toxicity in mice results in neurodevelopmental abnormalities with reactive astrogliosis and increased DNA damage in the fetal hippocampus. Our results demonstrate the potential importance of autophagy to elicit NP toxicity and the risk of indirect developmental neurotoxicity after maternal NP exposure.

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Fig. 1: NPs alter the autophagic flux in the upper layers of the BeWo barrier.
Fig. 2: Astrocytes in mixed NPC culture undergo morphological changes after indirect exposure to NPs.
Fig. 3: NPs increase the number of γ-H2AX foci in mixed astrocyte and neuronal cultures.
Fig. 4: Mechanism of NP-induced indirect toxicity is dependent on the presence of astrocytes and is triggered by autophagy in the BeWo barrier.
Fig. 5: GFAP and γ-H2AX levels are increased in the hippocampus of neonates after maternal exposure to CoCr NPs at E12.5.


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S.J.H. was supported by a fellowship from the Bristol Orthopaedic Trust. Work in the Caldwell lab is supported by Parkinson’s UK, James Tudor Foundation and EPSRC. We thank A. Schwartz (Washington University in St Louis) for permission to use the BeWo b30 cells, G. Cory (University of Exeter) for the modified pSEW sin vector and A. Rosser (Cardiff University) for providing the human fetal tissue for this work. The Cardiff Fetal Tissue Bank is funded by the MRC, NISCHR and Cardiff University. We also thank A. Blom for advice, A. Herman, S. Chappell, the University of Bristol Faculty of Biomedical Sciences Flow Cytometry Facility and I. T. Chang (School of Metallurgy and Materials, University of Birmingham).

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S.J.H., C.P.C. and M.A.C. conceived and designed the experiments, and C.P.C. and M.A.C. directed the work. S.J.H. completed the experiments with the help of L.A.C., O.C.-L., P.S., N.J.-M., S.F.M., C.E.G. and A.S., and also completed the data analysis with the help of M.A.C. J.D.L. oversaw the autophagy experiments and the lentiviral shRNA experiments, and M.S. provided advice on the BeWo barriers. S.K. performed the in vivo injections and the analysis was completed by A.B., N.T.B. and A.M.M. S.J.H., C.P.C. and M.A.C. wrote the paper and all the authors commented on it and agreed the final version.

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Correspondence to Maeve A. Caldwell.

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Hawkins, S.J., Crompton, L.A., Sood, A. et al. Nanoparticle-induced neuronal toxicity across placental barriers is mediated by autophagy and dependent on astrocytes. Nature Nanotech 13, 427–433 (2018).

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