Edinburgh Napier University

  Background and methods: Following exposure via a number of routes (inhalation, ingestion or injection), some
Nanomaterials (NMs) translocate to secondary tissues, prominently the liver. This study investigated the effects of an
array of NMs, varying in their physicochemical characteristics, consisting of two types of Zinc Oxide (ZnO), two Multiwalled
Carbon Nanotubes (MWCNT), one silver (Ag) and one titanium dioxide (TiO2) on the liver, following Intravenous
(IV) exposure of C57/BL6 mice. The animals were exposed to either a single dose of NM (128 μg/ml–100 μl) or three
doses of (64 μg/ml–100 μl), every 24 hr. Animals were dissected 6, 24, 48 and 72 hr after the single IV injection, or 72
hr after the triple injection regime.
Results and conclusions: A Myeloperoxidase (MPO) assay was utilised to quantify neutrophil influx into the
tissue. However, as MPO is also found in other granulocytes in smaller quantities, the neutrophils in the liver tissue were
also labelled, using a specific neutrophil cell surface marker (Ly-6B.2). A wide array of NMs (including ZnO, Ag, TiO2
and MWCNT) induced a neutrophil influx into the liver, as early as 6 hr post IV exposure. However, the neutrophils were
only involved in the initial phases of the immune response against the NMs, as the leukocyte numbers had returned to
control levels after 48 hr. Finally, analysis of mRNA expression in mice livers showed alterations in levels of C3, IL6,
IL10, CXCL2 and ICAM-1.