Background and objective: Hyperglycemia and inflammatory cytokines like interleukin (IL)-1beta play a key role in the vascular complications associated to diabetes melllitus (DM), such as atherosclerosis and hypertension. Understanding the pathophysiological mechanisms involved, including altered intercellular communication, is essential to identify potential therapeutical targets. We investigated the synergism of IL-1beta and high glucose on: (1) the activation of nucleotide-binding-oligomerization-domain, leucine-rich-repeat, and pyrin-domain-containing-3 (NLRP3)-inflammasome, an innate immunity component linked to vascular disease, and (2) the production and cargo of small extracellular vesicles (sEVs) as key players in vascular intercellular communication. Methods: Human aortic smooth muscle cells (HASMC) were challenged for 18 h with IL-1beta (10 ng/ml) in the presence of normal (5,5 mmol/L) or high glucose (22 mmol/L). Protein levels were quantified by Western blot, while the formation of ASC-like specks, reflecting NLRP3 activation, was assessed by indirect immunofluorescence. sEVs were determined by nanotracking analysis and endothelial senescence by the beta-galactosidase activity assay. Results: In HASMC cultures, IL-1beta favored NLRP3-inflammasome priming, as shown by NF-kappaB (phospho-p65) activation while NLRP3 and pro-IL-1beta levels were increased. The cytokine equally promoted NLRP3-inflammasome complex assembly, caspase-1 activation, and a subsequent release of mature IL-1beta in an auto-inflammatory loop. High glucose alone did not promote these effects, but it exacerbated some actions of IL-1beta and potentiated the release of HASMC-derived sEVs induced by IL-1beta, increasing their cargo content in NLRP3-inflammasome components. Moreover, these sEVs induce autocrine NLRP3-inflammasome activation in naïve HASMC and paracrine senescence in human endothelial cells. The IL-1 receptor blocker anakinra (1 mg/ml) blunted the IL-1beta effect, as well as their exacerbation by high glucose. Conclusion: High glucose exacerbates the activation of NLRP3-inflammasome by IL-1beta and alters intercellular communication by modifying the number and content of sEVs, which can expand inflammation in neighboring tissues. By preventing such synergy, biological drugs blocking IL-1beta receptors arise as potential pharmacological tools to attenuate DM associated vascular abnormalities.
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