Parra-Flores Pablo, Espitia-Corredor Jenaro, Espinoza-Pérez Claudio, Queirolo Cristian, Ayala Pedro, Brüggendieck Francisca, Salas-Hernández Aimee, Pardo-Jiménez Viviana, Díaz-Araya Guillermo
Laboratorio de Farmacología Molecular, Departamento de Química Farmacológica y Toxicológica, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile.
Department of Pharmacology, Faculty of Medicine, Instituto de Investigación Sanitaria Hospital Universitario La Paz, Universidad Autónoma de Madrid, Madrid, Spain.
Front Cardiovasc Med. 2021 Jun 8;8:660197. doi: 10.3389/fcvm.2021.660197. eCollection 2021.
Death of cardiac fibroblasts (CFs) by ischemia/reperfusion (I/R) has major implications for cardiac wound healing. In models of myocardial infarction, toll-like receptor 4 (TLR4) activation has been reported as a cardioprotector; however, it remains unknown whether TLR4 activation can prevent CF death triggered by simulated I/R (sI/R). In this study, we analyzed TLR4 activation in neonate CFs exposed to an model of sI/R and explored the participation of the pro-survival kinases Akt and ERK1/2. Simulated ischemia was performed in a free oxygen chamber in an ischemic medium, whereas reperfusion was carried out in normal culture conditions. Cell viability was analyzed by trypan blue exclusion and the MTT assay. Necrotic and apoptotic cell populations were evaluated by flow cytometry. Protein levels of phosphorylated forms of Akt and ERK1/2 were analyzed by Western blot. We showed that sI/R triggers CF death by necrosis and apoptosis. In CFs exposed only to simulated ischemia or only to sI/R, blockade of the TLR4 with TAK-242 further reduced cell viability and the activation of Akt and ERK1/2. Preconditioning with lipopolysaccharide (LPS) or treatment with LPS in ischemia or reperfusion was not protective. However, LPS incubation during both ischemia and reperfusion periods prevented CF viability loss induced by sI/R. Furthermore, LPS treatment reduced the sub-G1 population, but not necrosis of CFs exposed to sI/R. On the other hand, the protective effects exhibited by LPS were abolished when TLR4 was blocked and Akt and ERK1/2 were inhibited. In conclusion, our results suggest that TLR4 activation protects CFs from apoptosis induced by sI/R through the activation of Akt and ERK1/2 signaling pathways.
缺血/再灌注(I/R)导致的心脏成纤维细胞(CFs)死亡对心脏伤口愈合具有重要影响。在心肌梗死模型中,已有报道称Toll样受体4(TLR4)激活具有心脏保护作用;然而,TLR4激活是否能预防模拟I/R(sI/R)引发的CFs死亡仍不清楚。在本研究中,我们分析了暴露于sI/R模型的新生CFs中的TLR4激活情况,并探讨了促生存激酶Akt和ERK1/2的参与情况。模拟缺血在无氧培养箱中的缺血培养基中进行,而再灌注在正常培养条件下进行。通过台盼蓝排斥法和MTT法分析细胞活力。通过流式细胞术评估坏死和凋亡细胞群体。通过蛋白质印迹法分析Akt和ERK1/2磷酸化形式的蛋白质水平。我们发现sI/R通过坏死和凋亡触发CFs死亡。在仅暴露于模拟缺血或仅暴露于sI/R的CFs中,用TAK-242阻断TLR4会进一步降低细胞活力以及Akt和ERK1/2的激活。用脂多糖(LPS)预处理或在缺血或再灌注时用LPS处理均无保护作用。然而,在缺血和再灌注期间均进行LPS孵育可防止sI/R诱导的CFs活力丧失。此外,LPS处理减少了亚G1期群体,但未减少暴露于sI/R的CFs的坏死。另一方面,当TLR4被阻断且Akt和ERK1/2被抑制时,LPS表现出的保护作用被消除。总之,我们的结果表明,TLR4激活通过激活Akt和ERK1/2信号通路保护CFs免受sI/R诱导的凋亡。