CD73-enriched extracellular vesicles reduce cyclooxygenase 2 (COX-2)-mediated inflammation in activated macrophages.

[BACKGROUND] Extracellular ATP (eATP) enhances LPS-mediated activation of cyclooxygenase 2 (COX-2) leading to sustained inflammation. Previous work from our lab has shown that blocking of the purinergic P2 receptors, through which eATP acts, significantly reduced COX-2-mediated inflammation in macrophages and tumor progression in a mouse model of lymphoma. In this report, we test another approach to reduce eATP concentration through increasing the levels of the ectonucleotidase, CD73.

[METHODS] Extracellular vesicles (EVs) were isolated from CD73-transfected J774A.1 macrophage cells. CD73-rich EVs were then used to test the effect of eATP on LPS-treated cells.

[RESULTS] J774A.1 cells treated with both LPS and ATP released EVs rich in various pro-inflammatory cytokines and COX-2. Addition of CD73-rich EVs to macrophages treated with both LPS and ATP showed significant reduction in COX-2 expression. This reduction is due to a decrease in the activation of upstream nuclear factor κB (NF-κB) and reduced phosphorylation of cyclin-dependent kinase 9 (CDK9), key proteins involved in COX-2 transcription.

[CONCLUSIONS] Our study demonstrated that eATP enhanced LPS-mediated inflammation in macrophages which could be significantly reduced upon addition of CD73-rich EVs. Such engineered EVs can, therefore, be explored therapeutically for their anti-inflammatory properties.