Cardiovascular diseases (CVDs), including a series of high age-associated disorders, such as atherosclerosis, hypertension, and heart failure, have become a major issue threatening human health worldwide (Paneni et al., 2017; Smith et al., 2013). To date, the mechanisms underlying aging with respect to the development of CVD remain unclear (Evans et al., 2020). Reactive oxygen species (ROS) accumulation in vascular endothelial cells can promote the production of multiple proinflammatory chemokines and cytokines (Incalza et al., 2018; Zheng et al., 2022), thus leading to long-term, low-degree inflammation and ultimately cellular death and senescence (El Assar et al., 2013). Therefore, oxidative stress-associated cellular inflammation and senescence have been regarded as vital factors affecting vascular aging (Jia et al., 2019).

Previous studies have indicated that females are significantly protected from the development of CVD before menopause, having a reduced incidence of CVD compared with that in age-matched males (Nappi et al., 2022; Honigberg et al., 2019). This phenomenon could largely be explained by the protective effects of sex hormones prior to menopause (Torbati et al., 2022). 17β-Estradiol (17β-E2, estrogen), considered the most abundant form in peripheral circulation, can affect cardiovascular health through both direct effects on cardiovascular cells, such as cardiomyocytes and vascular cells, and indirect systemic effects. Estrogen can also influence cellular expression profiles, the activities of ion channels, and ROS production (Knowlton and Lee, 2012), and this could be involved in the regulation of many diseases. Moreover, estrogen can inhibit vascular endothelial cell senescence via multiple mechanisms, contributing to its protective effects on atherosclerosis and cardiac dysfunction (Colafella and Denton, 2018).

Thrombospondin-1 (THBS1), an adhesive glycoprotein originally discovered in platelets, can regulate cell phenotypes and extracellular structures during histogenesis and remodeling and mediate cell–cell and cell–matrix interactions (Kaur et al., 2021). This protein was first reported as an endogenous factor that inhibits angiogenesis and tumorigenesis, though more recent studies have found that THBS1 also has a role in promoting angiogenesis (Kale et al., 2021). The thrombospondin structural repeat sequences in THBS1 inhibit endothelial cell migration and promote apoptosis by interacting with the endothelial cell membrane proteins CD36 and CD47, thereby inhibiting angiogenesis (Roberts and Isenberg, 2021; Gutierrez and Gutierrez, 2021). Moreover, THBS1 might support the adhesion of tumor cells to endothelial cells and their invasion during tumor development by interacting with transforming growth factor beta (TGF-β) (Murphy-Ullrich and Suto, 2018; Sun et al., 2022). Of note, THBS1 expression is suppressed by estrogen in human umbilical vein endothelial cells (HUVECs) (Sengupta et al., 2004); however, whether estrogen exerts its protective effects on HUVECs by targeting this protein remains unclear.

Accordingly, we hypothesized that THBS1 suppression is indispensable for the protective effects of estrogen on vascular endothelial cells. To address this, we explored the vital role of THBS1 in hydrogen peroxide (H2O2)-induced HUVEC cell injury, verifying that the expression levels of THBS1 are affected by estrogen. We further investigated the underlying mechanisms linked to THBS1 and estrogen in affecting biological behaviors of HUVECs.