Low-dose cadmium telluride quantum dots trigger M1 polarization in macrophages through mTOR-mediated transcription factor EB activation

Abstract

The increasing application of quantum dots (QDs) increases interactions with organisms. The inflammatory imbalance is a significant manifestation of immunotoxicity. Macrophages maintain inflammatory homeostasis. Using macrophages differentiated by phorbol 12-myristate 13-acetate-induced THP-1 cells as models, the study found that low-dose (5 μM) cadmium telluride QDs (CdTe-QDs) hindered monocyte-macrophage differentiation. CD11b is a surface marker of macrophage, and the addition of CdTe-QDs during induction resulted in a decrease in CD11b expression. Moreover, exposure of differentiated THP-1 macrophage (dTHP-1) to 5 μM CdTe-QDs led to the initiation of M1 polarization. This was indicated by the increased surface marker CD86 expression, along with elevated level of NF-κB and IL-1β proteins. The potential mechanisms are being explored. The transcription factor EB (TFEB) plays a significant role in immune regulation and serves as a crucial regulator of the autophagic lysosomal pathway. After exposed to CdTe-QDs, TFEB activation-mediated autophagy and M1 polarization were observed to occur simultaneously in dTHP-1. The mTOR signaling pathway contributed to TFEB activation induced by CdTe-QDs. However, mTOR-independent activation of TFEB failed to promote M1 polarization. These results suggest that mTOR-TFEB is an advantageous target to enhance the biocompatibility of CdTe-QDs.