Maximakinin reversed H2O2 induced oxidative damage in rat cardiac H9c2 cells through AMPK/Akt and AMPK/ERK1/2 signaling pathways.

Maximakinin (MK), a homolog of bradykinin (BK), is extracted from skin venom of the Chinese toad Bombina maxima. Although MK has a good antihypertensive effect, its effect on myocardial cells is unclear. This study investigates the protective effect of MK on hydrogen peroxide (H2O2)-induced oxidative damage in rat cardiac H9c2 cells and explores its mechanism of action. A 3-(4,5-Dimethyl-2-Thiazolyl)-2,5-Diphenyl Tetrazolium Bromide (MTT) assay was selected to detect the effect of MK on H9c2 cell viability, while flow cytometry was used to investigate the influence of MK and H2O2 on intracellular reactive oxygen species (ROS) levels. Protein expression changes were detected by western blot. In addition, specific protein inhibitors were applied to confirm the induction of ROS-related signaling pathways by MK. MTT assay results show that MK significantly reversed H2O2-induced cell growth inhibition. Flow cytometry Dichlorodihydrofluorescein diacetate (DCFH-DA) staining shows that MK significantly reversed H2O2-induced increases in intracellular ROS production in H9c2 cells. Moreover, the addition of specific protein inhibitors suggests that MK reverses H2O2-induced oxidative damage by activating AMP-activated protein kinase (AMPK)/protein kinase B (Akt) and AMPK/extracellular-regulated kinase 1/2 (ERK1/2) pathways. Finally, an inhibitor of bradykinin B2 receptors (B2Rs), HOE-140, was applied to investigate potential targets of MK in H9c2 cells. HOE-140 significantly blocked induction of AMPK/Akt and AMPK/ERK1/2 pathways by MK, suggesting a potentially important role for B2Rs in MK reversing H2O2-induced oxidative damage. Above all, MK protects against oxidative damage by inhibiting H2O2-induced ROS production in H9c2 cells. The protective mechanism of MK may be achieved by activation of B2Rs to activate downstream AMPK/Akt and AMPK/ERK1/2 pathways.

Maximakinin reduced intracellular Ca2+ level in vascular smooth muscle cells through AMPK/ERK1/2 signaling pathways.

We detect the antihypertensive effects of maximakinin (MK) on renal hypertensive rats (RHRs) and further research the influence of MK on vascular smooth muscle cells (VSMCs) to explore its hypotensive mechanism. The effects of MK on arterial blood pressure were observed in RHRs. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) assays were performed to detect the effect of MK on VSMC viability. Western blot and flow cytometry were used to investigate the influence of MK on intracellular Ca2+ levels and protein expression changes in VSMCs. In addition, specific protein inhibitors were applied to confirm the involvement of Ca2+-related signaling pathways induced by MK in VSMCs. MK showed a more significant antihypertensive effect than bradykinin in RHRs. MK significantly decreased intracellular Ca2+ concentrations. Furthermore, MK significantly induced the phosphorylation of signaling molecules, including extracellular signal-regulated kinase 1/2 (ERK1/2), P38, AMP-activated protein kinase (AMPK) and Akt in VSMCs. Moreover, only ERK1/2 inhibitor U0126 and AMPK inhibitor Compound C completely restored the decreased intracellular Ca2+ level induced by MK, and further research demonstrated that AMPK functioned upstream of ERK1/2 following exposure to MK. Finally, HOE-140, an inhibitor of the bradykinin B2 receptors (B2Rs), was applied to investigate the potential targets of MK in VSMCs. HOE-140 significantly blocked the AMPK/ERK1/2 pathway induced by MK, suggesting that the B2Rs might play an important role in MK-induced AMPK and ERK1/2 activation. MK significantly reduces blood pressure in RHRs. MK exerts its antihypertensive effect by activating the B2Rs and downstream AMPK/ERK1/2 pathways, leading to significantly reduced Ca2+ levels in VSMCs.

Therapeutic outcomes of mycophenolate mofetil and glucocorticoid in thyroid-associated ophthalmopathy patients.

Objective: To analyze the efficacy of mycophenolate mofetil (MMF) and glucocorticoid administration in patients with thyroid-associated ophthalmopathy (TAO). Methods: Sixty patients with moderate to severe TAO treated in Jingzhou Central Hospital from January 2022 to June 2022 were selected and enrtolled in this study. The subjects were divided into experimental group (n=30) and control group (n=30) based on the random number table method. Glucocorticoid pulse therapy was provided in the control group, while MMF was given in the experimental group on the basis of Control group. Clinical activity score (CAS), quality of life (QOL), visual acuity, eyelid fissure width, intraocular pressure, and degree of exophthalmos were observed at the time of admission and at the 12th week and 24th post-treatment weeks. We compared the immune function (TRAb, IL-6, and CD4+/CD8+) of the two groups pre-treatment and 24 weeks post-treatment, and evaluated the clinical therapeutic effect. Results: The clinical effective rates at 12 and 24 weeks in the experimental group were higher (73.3% and 83.3%) than those in the control group (46.7% and 60.0%) (P <0.05). After 12 weeks of treatment, patients' CAS scores, and bilateral lid fissure width decreased and right eye visual acuity increased in the control group compared with those before treatment (P < 0.05); further, after 24 weeks of treatment, patients' QOL scores and bilateral visual acuity increased and CAS scores, bilateral lid fissure width and proptosis decreased compared with those before treatment, and patients' QOL scores, CAS scores and bilateral proptosis improved more than those at 12 weeks of treatment (P <0.05). Additionally, greater improvements were observed in the patients' QOL and CAS scores, and proptosis after 24-week treatment than after 12-week treatment (P<0.05). In the experimental group, the QOL score and binocular visual acuity increased, whereas the CAS score, intraocular pressure, lid width, and proptosis decreased after 12 weeks of treatment as compared to the values of these parameters in the pre-treatment period (P < 0.05); after 24 weeks of treatment, greater improvements were established in the ocular-related indexes improved compared to the pre-treatment period and after 12 weeks of treatment (P < 0.05). After 12 weeks of treatment, the patients in the experimental group had more considerable improvements in the right visual acuity, right intraocular pressure, and left lid fissure width than the control group (P < 0.05); at 24 weeks of treatment, patients in the experimental group had greater improvements in the QOL score, bilateral visual acuity, intraocular pressure, bilateral lid fissure width, and bilateral proptosis than the control group (P < 0.05). No significant differences were found in the values of TRAb, IL-6, and CD4+/CD8+ between the two groups before treatment (P>0.05); the values of TRAb, IL-6, and CD4+/CD8+ in the experimental group was significantly lower than those before treatment and in the control group after 24weeks of treatment. (P>0.05). No statistically significant difference was observed in the incidence of liver damage and menstrual disorders between the two groups during the 24 weeks of treatment (P>0.05). Conclusion: The combination of oral MMF and glucocorticoid shock therapy is an effective drug for the treatment of patients with moderately active TAO.

The antihypertensive effect of MK on spontaneously hypertensive rats through the AMPK/Akt/eNOS/NO and ERK1/2/Cx43 signaling pathways.

We investigated the antihypertensive effects of maximakinin (MK) on spontaneously hypertensive rats (SHRs). The effects of MK on arterial blood pressure in SHRs were observed, and flow cytometry and 4,5-diaminofluorescein-2 staining were used to examine MK-induced nitric oxide (NO) release in human umbilical vein endothelial cells (HUVECs). Western blotting was used to analyze the effects of MK on the expression of AMP-activated protein kinase (AMPK), Akt, Connexin 43, ERK1/2, p38, and p-eNOS in HUVECs. The results showed that MK induced a more significant antihypertensive effect on SHRs than bradykinin (BK). MK induced significant increases in endothelial nitric oxide synthase (eNOS) phosphorylation and NO release in HUVECs. MK also significantly increased the phosphorylation of Akt and AMPK in HUVECs. The AMPK inhibitor compound C blocked the effect of MK on the generation of NO. MK induced the phosphorylation of ERK1/2, p38, and Connexin 43. The expression of p-Connexin 43 was significantly decreased in the presence of the ERK1/2 inhibitor U0126 but not the p38 inhibitor SB203580. The effects of MK on the phosphorylation of AMPK and ERK1/2 were significantly decreased by the BK B2 receptor inhibitor HOE-140. In summary, MK can significantly reduce blood pressure in SHRs. The antihypertensive effect might be mediated through the activation of the BK B2 receptor, while the downstream AMPK/PI3K/Akt/eNOS/NO and ERK1/2/Connexin 43 signaling pathways play additional roles.