Inflammation and accompanied disrupted hematopoiesis in adult mouse induced by rare earth element nanoparticles.

Rare earth element nanoparticles (REE NPs) or agents have been used extensively in various fields. Human exposure to REE NPs is an increasing concern. To date, REE NP-mediated comprehensive immune responses after incorporation into the body remain unclear. In our study, using gadolinium oxide NPs (Gd ₂ O ₃ ) as a typical REE NP, we systematically investigated immune responses in vivo. The liver and spleen were the main sites where Gd ₂ O ₃ retained and accumulated, while Gd ₂ O ₃ content per unit tissue mass in the spleen was 4.4 times higher than that in the liver. Gd ₂ O ₃ increased the number of monocyte-derived macrophages and myeloid-derived dendritic cells (M-DCs) in the liver. In the spleen, Gd ₂ O ₃ caused infiltration of neutrophils, M-DCs, and B cells. The accumulation of Gd ₂ O ₃ in the liver or spleen also contributed to an increased concentration of cytokines in peripheral blood. In both the bone marrow and spleen, Gd ₂ O ₃ led to increased populations of hematopoietic stem cells (HSCs), multipotent progenitors, and common lymphoid progenitors. Compared to the decreased monocytes in peripheral blood on day 2, a significant decrease of circulating lymphocytes on day 7 was still observed, suggesting the exposure duration led to variable effects. This might be explained by the sustained accumulation of Gd ₂ O ₃ in the liver and spleen. Together, our study systemically depicted the alterations in mature immune alterations together with hematopoiesis in both myeloid and lymphoid lineages induced by Gd ₂ O ₃ exposure. Our findings will facilitate a comprehensive understanding of the interactions of immune system with REE NPs in vivo.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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