The environmental burden of flame retardants, including PBDEs, necessitates a deep understanding of their biological consequences. 2,2',4,4'-tetrabromodiphenyl ether (PBDE-47) is a prominent example, and recent research is uncovering its subtle yet significant impacts on the immune system, particularly through the signaling pathways mediated by extracellular vesicles (EVs).

Macrophages, essential components of the immune system, are responsible for defending the body against pathogens and maintaining tissue homeostasis. Their ability to polarize into different functional states is key to mounting appropriate responses. This study explored how PBDE-47 influences this dynamic process by focusing on the role of EVs released by activated macrophages.

The research revealed that PBDE-47 exposure led to alterations in the miRNA composition of EVs released by stimulated macrophages. These EVs then served as carriers of these molecular changes to naive macrophages. Upon internalizing these PBDE-47-modified EVs, the recipient macrophages showed altered intracellular miRNA profiles, suggesting a cascade of downstream effects on cellular regulation.

Functionally, the treatment of macrophages with these PBDE-47-laden EVs resulted in a significant decrease in the expression of critical surface markers such as HLA-DR and CD209. These markers play vital roles in immune cell interactions and antigen presentation. The observed downregulation indicates that PBDE-47, indirectly transmitted via EVs, may impair the macrophages' capacity for effective immune surveillance and activation. This research provides valuable insights into the complex mechanisms of immunotoxicity caused by environmental chemicals, highlighting the importance of EVs in mediating these effects. NINGBO INNO PHARMCHEM CO.,LTD. is a key supplier of chemicals like PBDE-47, enabling researchers to conduct crucial studies in environmental toxicology and immunology.