With the continuous improvement of global living standards, a high-fat diet (HFD) has become one of the most common and unhealthy lifestyles leading to obesity, and the intake of a large amount of saturated fatty acids leads to inflammation and the development of cardiovascular diseases (CVDs) [1,2].

Palmitic acid (PA), as the most abundant saturated fatty acid in the blood, usually increases in obese patients and obese animal models [3,4]. High concentrations of PA have been reported to induce mitochondrial dysfunction, increased ROS production, oxidative stress, changes in mitochondrial membrane potential (MMP) [5] and pyroptosis in hepatocytes [6]. However, there are few studies on the pyroptosis of vascular endothelial cells (VECs) caused by PA [7].

VECs are a single layer of epithelial cells lining the inside of blood vessels, and endothelial dysfunction (ED) is an early hallmark and predictor of CVD [8]. Recently, pyroptosis induced by inflammasomes has represented a novel mechanism for ED in atherosclerosis and other CVDs [9,10]. Pyroptosis, an inflammatory programmed cell death process, mainly includes the caspase-1-mediated classical pathway and caspase-4/5/11-dependent nonclassical pathway. Both of the activated pathways cleaves gasdermin D (GSDMD), resulting in the production of the pore-forming molecule GSDMD N-terminal domain (GSDMD-N) and pore formation in the plasma membrane, the release of interleukin-1β (IL-1β), IL-18 and lactate dehydrogenase (LDH), and cell swelling and rupture [11,12]. Recently, hyperlipidemia has been reported to activate caspase-1, which cleave and activate GSDMD [13,14].

Pyroptosis occurs due to the activation of different inflammasomes, which are usually protein complexes in the cytoplasm that can sense pathogens under physiological and pathological conditions [15]. Oxidative stress is known to activate the NLR-family pyrin domain-containing protein 3 (NLRP3) inflammasome, promotes the cleavage and release of pro-interleukin (IL)−1β and pro-IL-18 by caspase-1, and mediates the occurrence of vascular inflammation in ED [16].

The accumulation of reactive oxygen species (ROS) in mitochondria is a main source of oxidative stress. After phosphorylation and activation, the redox adaptor protein p66shc is transferred from cytoplasm to mitochondria, causing the production of mitochondrial ROS [17]. As a direct target molecule of Sirtuin-1 (SIRT1), p66Shc can also be deacetylated and inhibited by SIRT1 to reduce ROS production [18]. PA-induced insulin resistance and pancreatic β-cell death have been studied and found to be associated with increased p53-dependent p66Shc expression [19,20]. However, the role and mechanism of p66Shc in endothelial pyroptosis induced by PA have not been elucidated.

Resveratrol (RSV), a polyphenol compound (3,5,4′-trihydroxystilbene), is a natural activator of SIRT1 and has a wide range of protective effects against the toxic effects of high sugar and fat [[21], [22], [23], [24]]. More recently, the specific mechanism by which RSV protects blood vessels has been linked to its anti-inflammatory, antioxidant and immunoregulatory activities [25,26]. RSV protects against a high-fat diet-induced neuroinflammation by suppressing aberrant mitochondrial fission possibly through triggering the SIRT1/PGC-1α axis [27]. However, the role of RSV in PA-induced endothelial pyroptosis has not been reported.

The purpose of the present study was to explore whether HFD and PA-induced pyroptosis of VECs and the protective effect of RSV are related to the NLRP3 inflammasome and downstream GSDMD by the SIRT1-p66Shc axis.At the same time, whether EX527, as a specific inhibitor of SIRT1, can reverse the protective effect of RSV.