α-Lipoic acid alleviates myocardial injury and induces M2b macrophage polarization after myocardial infarction via HMGB1/NF-kB signaling pathway.

Myocardial infarction (MI) is a serious cardiovascular disease with a poor prognosis. Macrophages are the predominant immune cells in patients with MI and macrophage regulation during the different phases of MI has important consequences for cardiac recovery. Alpha-lipoic acid (ALA) plays a critical role in MI by modulating the number of cardiomyocytes and macrophages. MI mice were generated by ligating the left anterior descending coronary artery. Macrophages were exposed to hypoxia to establish a hypoxia model and M1 polarization was induced by LPS and IFN-γ. Different groups of macrophages and MI mice were treated with ALA. The cardiomyocytes were treated with various macrophage supernatants and the cardiac function, cytokine levels, and pathology were also analyzed. Factors related to apoptosis, autophagy, reactive oxygen species (ROS), and the mitochondrial membrane potential (MMP) were assessed. Finally, the HMGB1/NF-κB pathway was identified. ALA promoted M2b polarization in normal cells and suppressed inflammatory cytokines during hypoxia. ALA inhibited ROS and MMP production in vitro. Supernatants containing ALA inhibited apoptosis and autophagy in hypoxic cardiomyocytes. Moreover, ALA suppressed the HMGB1/NF-κB pathway in macrophages, which may be a potential mechanism for attenuating MI. ALA alleviates MI and induces M2b polarization via the HMGB1/NF-κB pathway, impeding inflammation, oxidation, apoptosis, and autophagy, and might be a potential strategy for MI treatment.

Wang Y ，Zheng Y ，Qi B ，Liu Y ，Cheng X ，Feng J ，Gao W ，Li T ... -  《-》

Alpha-lipoic acid impedes myocardial ischemia-reperfusion injury, myocardial apoptosis, and oxidative stress by regulating HMGB1 expression.

Inflammation, oxidative stress, and apoptosis contribute to myocardial ischemia/reperfusion injury (I/RI). Alpha-lipoic acid (ALA) plays a critical role in I/RI by impeding apoptosis and inflammation. Here, we aimed to explore the underlying mechanisms of ALA after I/RI. The left anterior descending coronary artery (LAD) was ligated, and H9c2 cells were exposed to hypoxia/reoxygenation (H/R) to establish an I/RI model. Prior to this, H9c2 cells and rats were treated using an appropriate amount of ALA. The cardiac function, inflammatory factors, and myocardial pathology were assessed in vitro. We detected cell viability, apoptosis, and oxidative stress-related factors in vivo. Moreover, proteins of the HMGB1/TLR4/NF-κB signaling pathway were detected both in vivo and in vitro. We observed that ALA increased cell viability in vitro and decreased apoptosis in vitro and in vivo. ALA inhibited reactive oxygen species production, decreased malondialdehyde, and increased superoxide dismutase activity to resist oxidative stress in vitro. ALA also reduced the expression of inflammatory cytokines (IL-6, IL-1β, and TNF-α) in vivo. ALA also suppressed the levels of the apoptotic protein, Bax, and increased the expression of the anti-apoptotic protein Bcl-2, in vitro and in vivo. Moreover, we observed that ALA significantly inhibited the cytoplasmic localization of HMGB1, which might attenuate MI/RI or H/R via HMGB1/TLR4/NF-κB pathway. ALA regulates HMGB1 translocation and attenuates I/R via the HMGB1/TLR4/NF-κB signaling pathway, thus impeding apoptosis, oxidation, and inflammation, and might be a potential target for myocardial ischemia/reperfusion injury.

Qi B ，Zheng Y ，Gao W ，Qi Z ，Gong Y ，Liu Y ，Wang Y ，Cheng X ，Ning M ，Lang Y ，Feng J ，Li T ... -  《-》

Diannexin alleviates myocardial ischemia-reperfusion injury by orchestrating cardiomyocyte oxidative damage, macrophage polarization and fibrotic process by TLR4-NF-kB-mediated inactivation of NLRP3 inflammasome.

Myocardial ischemia-reperfusion (I/R) injury is a pathogenic mechanism of myocardial infarction and heart failure, constituting a major health concern globally. Diannexin is a homodimer of recombinant human annexin V and elicits important roles in several I/R injuries. Nevertheless, its function in MI/R remains elusive. Here, Diannexin alleviated simulated I/R (SI/R)-induced cardiomyocyte death and oxidative injury by increasing cell viability and inhibiting cell apoptosis, ROS, lactate dehydrogenase, malondialdehyde production and anti-oxidative SOD activity. Diannexin inhibited SI/R-induced expression of fibrotic protein collagen I and collagen III. Furthermore, Diannexin suppressed LPS-induced macrophage polarization towards pro-inflammatory M1-like phenotype and enhanced IL-4-evoked anti-inflammatory M2 polarization. Concomitantly, Diannexin inhibited SI/R exposure-induced macrophage polarization to M1 subtypes. Importantly, conditioned medium (CM) from SI/R-stimulated macrophages evoked cardiomyocyte apoptosis, which was reversed when cells were co-cultured with CM from Diannexin-treated macrophages under SI/R conditions. Mechanically, the activation of TLR4/NF-κB/NLRP3 inflammasome signaling in SI/R-treated cells was mitigated by Diannexin. Reactivating this pathway antagonized the protective effects of Diannexin on SI/R-induced cardiomyocyte oxidative injury, fibrotic protein expression and macrophage polarization and M1 macrophage-induced apoptosis of cardiomyocytes. In vivo, Diannexin alleviated abnormal cardiac structure, dysfunction and collagen position in MI/R mice. Additionally, Diannexin reduced M1-polarized and elevated M2-polarized macrophages in heart tissues at five days post-MI/R. The activation of TLR4/NF-κB/NLRP3 inflammasome pathway in MI/R mice was attenuated after Diannexin administration. Together, Diannexin may alleviate the development of MI/R injury by directly regulating cardiomyocyte oxidative injury, fibrotic potential and indirectly affecting macrophage polarization-mediated cardiomyocyte apoptosis, indicating a promising therapeutic strategy for MI/R.

Zhang L ，Zhao S ，Wang Y 《-》

miR-708 affords protective efficacy in anoxia/reoxygenation-stimulated cardiomyocytes by blocking the TLR4 signaling via targeting HMGB1.

Ischemic heart disease is a proverbial and common cardiovascular disease, and constitutes a leading cause of disability and mortality globally. Myocardial ischemic/reperfusion (MI/R) injury is a highly orchestrated phenomenon that involves the excessive activation of high mobility group box 1 (HMGB1) signaling. In the present study, we sought to investigate the function of miR-708 in MI/R injury due to the predicted binding to HMGB1. Intriguingly, down-regulation of miR-708 and up-regulation of HMGB1 were observed in MI/R rat model and H9c2 cardiomyocytes exposed to hypoxia/reoxygenation (H/R) conditions. Dual luciferase reporter assays substantiated that HMGB1 was a direct target of miR-708. Moreover, miR-708 overexpression suppressed the mRNA and protein expression of HMGB1. Noticeably, elevation of miR-708 antagonized H/R-induced inhibition in cell viability; whilst, increased cell apoptosis evoked by H/R was restrained after miR-708 up-regulation. Simultaneously, miR-708 elevation suppressed H/R exposure-increased lactate dehydrogenase (LDH) release and reactive oxygen species (ROS) generation, but elevated the activity of anti-oxidative stress superoxide dismutase (SOD). Additionally, H/R-increased production of pro-inflammatory cytokine TNF-α and IL-6 was offset following miR-708 overexpression. Moreover, enhancement of miR-708 inhibited H/R-evoked activation of the HMGB1-TLR4-NF-κB pathway by inhibiting the protein levels of HMGB1, TLR4 and p-p65 NF-κB. Specially, restoring this pathway offset the protective effects of miR-708 on H/R-induced cardiomyocyte injury. Together, these data indicate that miR-708 may protect against H/R-induced cardiomyocyte damage by directing targeting HMGB1 signaling, implying a promising therapeutic agent against ischemic heart disease including myocardial infarction.

Zhang S ，Wang Y ，Wang P ，Xuan J ... -  《-》

MicroRNA-155 inhibition attenuates endoplasmic reticulum stress-induced cardiomyocyte apoptosis following myocardial infarction via reducing macrophage inflammation.

Endoplasmic reticulum stress (ERS)-induced cardiomyocyte apoptosis plays an important role in the pathological process following myocardial infarction (MI). Macrophages that express microRNA-155 (miR-155) mediate cardiac inflammation, fibrosis, and hypertrophy. Therefore, we investigated if miR-155 regulates ERS-induced cardiomyocyte apoptosis after MI using a mouse model, lipopolysaccharide (LPS)-induced rat bone marrow derived macrophages (BMDMs)and hypoxia-induced neonatal rat cardiomyocytes (NRCMs). In vivo, miR-155 levelswere significantly higher in the MI group compared to the sham group. MI increasedmacrophage infiltration, nuclear factor-κB (NF-κB) activation, ERS induced-apoptosis, and SOCS1 expression, all of which were attenuated by the miR-155 antagomir, with the exception of SOCS1 expression. Additionally, post-MI cardiac dysfunction was significantly improved by miR-155 inhibition. In vitro, LPS upregulated miR-155 expression in BMDMs, and the miR-155 antagomir decreased LPS-induced macrophage inflammation and NF-κB pathway activation, but increased expression of SOCS1. Hypoxia increased NF-κB pathway activation, ERS marker expression, and apoptosis in NRCMs. Interestingly, conditioned medium from LPS-induced macrophages in combination with the miR-155 antagomir decreased, while the miR-155 agomir increased, the hypoxia-induced effects in NRCM's. The miR-155 agomir effects were reversed by inhibiting the NF-κB pathway in cardiomyocytes. Moreover, SOCS1 knockdown in LPS-induced macrophages promoted NF-κB pathway activation and ERS-induced cardiomyocyte apoptosis in the hypoxia-induced NRCMs, but the SOCS1-siRNA-induced effects were markedly decreased by miR-155 antagomir treatment. These data suggest that miR-155 inhibition attenuates ERS-induced cardiomyocyte apoptosis after MI via reducing macrophage inflammation through the SOCS1/NF-κB pathway.

Hu J ，Huang CX ，Rao PP ，Cao GQ ，Zhang Y ，Zhou JP ，Zhu LY ，Liu MX ，Zhang GG ... -  《-》