Endothelium‐Specific Acid Ceramidase Gene Deletion Enhances Exosome Secretion and Release of NLRP3 Inflammasome Products during Hyperglycemia

Abstract

Exosomes have been demonstrated to be one of the mechanisms mediating the release of a variety of intracellular signaling molecules to mediate cell‐to‐cell communication. However, it remains unknown whether exosomes mediate the release of Nod‐like receptor pyrin domain 3 (NLRP3) inflammasome products such as IL‐1β from endothelial cells and how exosome‐mediated‐inflammatory signaling is regulated. The present study hypothesized that lysosomal acid ceramidase (AC) determines the fate of the multivesicular body (MVB) to control the exosome‐mediated release of NLRP3 inflammasome products during hyperglycemia. Using streptozotocin (STZ)‐induced mouse model of diabetes mellitus (DM), we found that endothelium‐specific AC gene knock‐out mice (Asah1fl/fl/ECcre) had significantly enhanced formation and activation of NLRP3 inflammasomes including IL‐1β production in the coronary arterial endothelium. These mice also had increased thickening of the coronary arterial wall and reduced expression of tight junction protein (ZO‐1 and ZO‐2) compared to their wild‐type (WT/WT) littermates. Interestingly, we observed that the expression of exosome markers such as CD63 and alkaline phosphatase (ALP) was also augmented in STZ‐treated Asah1fl/fl/ECcre mice compared to WT/WT mice, which was accompanied by an increased IL‐1β release of exosomes into the blood. In the primary cultures of coronary endothelial cells (CECs) from WT/WT and Asah1fl/fl/ECcre mice, we demonstrated that the AC deficiency markedly enhanced the formation and activation of the NLRP3 inflammasomes, but significantly down‐regulated tight junction proteins when CECs were exposed to high levels of glucose. The CECs from Asah1fl/fl/ECcre mice also had decreased MVBs and increased exosome release in response to high glucose stimulation and these exosomes contained increased IL‐1β. These results from our in vivo and in vitro experiments suggest that AC importantly controls exosome secretion and release of NLRP3 inflammasome products in CECs and its deficiency enhances this exosome‐mediated release of NLRP3 inflammasome products to activate coronary arterial inflammatory response during hyperglycemia.Support or Funding InformationHL057244, HL075316, and DK120491This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.