Kim Hyoseon, Massett Michael P
Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, TX, United States.
Front Physiol. 2024 Aug 21;15:1446836. doi: 10.3389/fphys.2024.1446836. eCollection 2024.
Endothelial function is significantly impaired in patients with SLE compared to healthy controls. Elevated activation of the mammalian target of rapamycin complex 1 (mTORC1) is reported in humans and mice with SLE. However, it is unclear if elevated mTORC1 in SLE contributes to impaired mitophagy and endothelial dysfunction. Therefore, we tested the hypothesis that inhibiting mTORC1 with rapamycin would increase mitophagy and attenuate endothelial dysfunction and inflammatory responses in SLE.
Nine-week-old female lupus-prone (MRL/lpr) and healthy control (MRL/MpJ) mice were randomly assigned into rapamycin treatment (lpr_Rapamycin and MpJ_Rapamycin) or control (lpr_Control and MpJ_Control) groups. Rapamycin was injected i.p. 3 days per week for 8 weeks. After 8 weeks, endothelium-dependent vasorelaxation to acetylcholine (ACh) and endothelium-independent vasorelaxation to sodium nitroprusside (SNP) were measured in thoracic aortas using a wire myograph.
MTORC1 activity was increased in aorta from lpr mice as demonstrated by increased phosphorylation of s6rp and p70s6k and significantly inhibited by rapamycin (s6rp, < 0.0001, p70s6k, = 0.04, respectively). Maximal responses to Ach were significantly impaired in lpr_Control (51.7% ± 6.6%) compared to MpJ_Control (86.7% ± 3.6%) ( < 0.0001). Rapamycin prevented endothelial dysfunction in the thoracic aorta from lupus mice (lpr_Rapamycin) (79.6% ± 4.2%) compared to lpr_Control ( = 0.002). Maximal responses to SNP were not different across groups. Phosphorylation of endothelial nitric oxide synthase also was 42% lower in lpr_Control than MpJ_Control and 46% higher in lpr_Rapamycin than lpr_Control. The inflammatory marker, vascular cell adhesion protein 1 (Vcam 1), was elevated in aorta from lupus mice compared with healthy mice ( = 0.001), and significantly reduced with Rapamycin treatment ( = 0.0021). Mitophagy markers were higher in lupus mice and reduced by rapamycin treatment, suggesting altered mitophagy in lpr mice.
Collectively, these results demonstrate the beneficial effects of inhibiting mTORC1 on endothelial function in SLE mice and suggest inflammation and altered mitophagy contribute to endothelial dysfunction in SLE.
与健康对照相比，系统性红斑狼疮（SLE）患者的内皮功能明显受损。在患有SLE的人类和小鼠中，已报道雷帕霉素靶蛋白复合物1（mTORC1）的激活升高。然而，尚不清楚SLE中mTORC1升高是否会导致线粒体自噬受损和内皮功能障碍。因此，我们检验了以下假设：用雷帕霉素抑制mTORC1会增加线粒体自噬，并减轻SLE中的内皮功能障碍和炎症反应。
将9周龄的雌性狼疮易感（MRL/lpr）小鼠和健康对照（MRL/MpJ）小鼠随机分为雷帕霉素治疗组（lpr_Rapamycin和MpJ_Rapamycin）或对照组（lpr_Control和MpJ_Control）。每周腹腔注射雷帕霉素3天，共8周。8周后，使用线肌张力测定仪测量胸主动脉对乙酰胆碱（ACh）的内皮依赖性血管舒张和对硝普钠（SNP）的非内皮依赖性血管舒张。
如s6rp和p70s6k磷酸化增加所示，lpr小鼠主动脉中的MTORC1活性增加，雷帕霉素可显著抑制该活性（s6rp，<0.0001；p70s6k，=0.04）。与MpJ_Control（86.7%±3.6%）相比，lpr_Control中对Ach的最大反应显著受损（51.7%±6.6%）（<0.0001）。与lpr_Control相比，雷帕霉素可预防狼疮小鼠胸主动脉的内皮功能障碍（lpr_Rapamycin）（79.6%±4.2%）（=0.002）。各组对SNP的最大反应无差异。内皮型一氧化氮合酶的磷酸化在lpr_Control中也比MpJ_Control低42%，在lpr_Rapamycin中比lpr_Control高46%。炎症标志物血管细胞黏附蛋白1（Vcam 1）在狼疮小鼠主动脉中比健康小鼠升高（=0.001），雷帕霉素治疗后显著降低（=0.0021）。狼疮小鼠中线粒体自噬标志物较高，雷帕霉素治疗后降低，提示lpr小鼠中线粒体自噬改变。
总体而言，这些结果证明了抑制mTORC1对SLE小鼠内皮功能的有益作用，并表明炎症和线粒体自噬改变导致SLE中的内皮功能障碍。
