Role of CAPE on cardiomyocyte protection via connexin 43 regulation under hypoxia

Protective effects of propolis on ischemia-reperfusion injury in a rat testicular torsion and detorsion model

The torsion model of testis in a rat was adopted for evaluation of possible effects of propolis (Prop) on ischemia-reperfusion (IS/REP) injury. The healthy male Wistar rats (totally 24 animals) were randomized into four groups (n = 6) and animals experienced bilateral testicular torsions as follows: In sham group just, laparotomy was performed and in IS group, animals experienced a 3 hr period testicular IS. In IS/REP group, a 3 hr period of IS followed by a 3 hr period of testicular REP for left testis and a one-week testicular REP for right testis were done. In this group animals were gavaged by 1.00 mL normal saline 1 hr before the onset of IS. In IS/REP/ Prop group, the same procedures for IS/REP animals were followed as well as gavage of 1.00 mL Prop extract solution 1 hr before the onset of IS. Analyses of biochemistry, histology, inflammatory biomarkers and sperm parameters were carried out. In IS/REP/Prop group, nitric oxide synthase malondialdehyde, myeloperoxidase and 8-hydroxy-2 deoxyguanine in IS/REP/Prop group were significantly decreased and, superoxide dismutase, total glutathione, glutathione peroxidase, glutathione reductase and glutathione S-transferase were significantly increased compared to the other animals. In IS/REP/Prop group, seminiferous tubules (with normal spermatogenesis) showed all stages of spermatogenic cells with plentiful spermatozoa. Tubular deterioration and atrophy and spermatogenic cell loss in were seen in a limited extent. The mean concentrations of Interleukin-1 beta and tumor necrosis factor alpha in IS/REP/Prop were significantly decreased. Sperm quality was significantly improved by Prop in IS/REP/Prop group. It was concluded that Prop could be supportive in diminishing IS/REP injury in testicular tissue exposed to ischemia.

Evaluation of Effect of Biologically Synthesized Ethanolic Extract of Propolis-Loaded Poly(-Lactic-co-Glycolic Acid) Nanoparticles on Wound Healing in Diabetic Rats

Wound healing is interaction of a complex cascade of cellular/biochemical actions leading to restoration of structural and functional integrity with regain of injured tissues strength. This study was aimed at evaluation of application of ethanolic extract of propolis-loaded poly(-lactic-co-glycolic acid) nanoparticles (EEP-PLGA NPs) on wound healing in diabetic rats. Sixty rats were randomized into four groups of 15 rats each: In control group (Control) diabetic wound was treated with normal saline. In Carrier 1 group diabetic wound was treated with PLGA nanoparticles based solution. In Carrier 2 group the diabetic wound was treated with EEP. In Treatment group animals received EEP-PLGA NPs on the wound. Wound size was measured on 7, 14 and 21 days after surgery. The expression of p53, bcl-2, Caspase III, were evaluated using reverse-transcription PCR and Immunohistochemical staining. The Treatment group had significantly reduced the wound size compared to other groups (P = 0.001). histological and morphometric studies, and mean rank of the qualitative studies demonstrated that there was significant difference between Treatment group and other groups (P < .05). Observations demonstrated that ethanolic extract of propolis-loaded PLGA nanoparticles significantly shortened the inflammatory phase and accelerated the cellular proliferation. Accordingly, the animals in Treatment group revealed significantly (P < .05) higher fibroblast distribution/one mm2 of wound area and rapid re epithelialization. The mRNA levels of bcl-2, p53 and caspase III were remarkably (P < .05) higher in Treatment group compared to control and animals. The immunohistochemical analyzes confirmed the RT-PCR findings. EEP-PLGA NPs offered potential advantages in wound healing acceleration and improvement through angiogenesis stimulation, fibroblast proliferation and granulation tissue formation in early days of healing phases, acceleration in diabetic wound repair associated with earlier wound contraction and stability of damaged area by rearrangement of granulation tissue and collagen fibers.

The mechanisms through which auricular vagus nerve stimulation protects against cerebral ischemia/reperfusion injury

Previous studies have shown that vagus nerve stimulation can improve patients' locomotor function. The stimulation of the auricular vagus nerve, which is the only superficial branch of the vagus nerve, may have similar effects to vagus nerve stimulation. However, the precise mechanisms remain poorly understood. In this study, rat models of cerebral ischemia/reperfusion injury were established by modified Longa ligation. Twenty-four hours later, 7-day auricular vagus nerve stimulation was performed. The results showed that auricular vagus nerve stimulation promoted the secretion of acetylcholine, inhibited the secretion of interleukin-1β, interleukin-6, and tumor necrosis factor-α, and reduced connexin 43 phosphorylation in the ischemic penumbra and motor cortex, promoting locomotor function recovery in rats with cerebral ischemia/reperfusion injury. These findings suggested that auricular vagus nerve stimulation promotes the recovery of locomotor function in rats with cerebral ischemia/reperfusion injury by altering the secretion of acetylcholine and inflammatory factors and the phosphorylation of connexin 43. This study was approved by the Animal Use and Management Committee of Shanghai University of Traditional Chinese Medicine on November 8, 2019 (approval No. PZSHUTCM191108014).

HIF-1α promotes the proliferation and migration of pulmonary arterial smooth muscle cells via activation of Cx43

The proliferation of pulmonary artery smooth muscle cells (PASMCs) is an important cause of pulmonary vascular remodelling in hypoxia-induced pulmonary hypertension (HPH). However, its underlying mechanism has not been well elucidated. Connexin 43 (Cx43) plays crucial roles in vascular smooth muscle cell proliferation in various cardiovascular diseases. Here, the male Sprague-Dawley (SD) rats were exposed to hypoxia (10% O₂ ) for 21 days to induce rat HPH model. PASMCs were treated with CoCl₂ (200 µM) for 24 h to establish the HPH cell model. It was found that hypoxia up-regulated the expression of Cx43 and phosphorylation of Cx43 at Ser 368 in rat pulmonary arteries and PASMCs, and stimulated the proliferation and migration of PASMCs. HIF-1α inhibitor echinomycin attenuated the CoCl₂ -induced Cx43 expression and phosphorylation of Cx43 at Ser 368 in PASMCs. The interaction between HIF-1α and Cx43 promotor was also identified using chromatin immunoprecipitation assay. Moreover, Cx43 specific blocker (^37,43 Gap27) or knockdown of Cx43 efficiently alleviated the proliferation and migration of PASMCs under chemically induced hypoxia. Therefore, the results above suggest that HIF-1α, as an upstream regulator, promotes the expression of Cx43, and the HIF-1α/Cx43 axis regulates the proliferation and migration of PASMCs in HPH.

CEACAM-1 promotes myocardial injury following coxsackievirus infection by regulating the coxsackievirus-adenovirus receptor

OBJECTIVE

To determine the effects and mechanism of carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM-1, CC1)-mediated regulation of the Coxsackie and Adenovirus Receptor (CAR) after Coxsackievirus B3 (CVB3) infection.

METHODS

A mouse CC1 overexpression recombinant virus was constructed, followed by insertion of a pLVX-CEACAM 1-zsgreen-puro (rLV-CEACAM 1) plasmid into the recombinant retrovirus. Cardiac myocytes were assigned into different groups according to various treatments. The apoptosis rate and cell activity in each group were observed. Further, CAR expression and SYK, IL-1β, and p-SYK levels were measured.

RESULTS

The recombinant retrovirus titer was measured as 1.5 × 10 TUs/ml. The apoptosis rate of cardiac myocytes in the CC1 overexpression plus CVB3 group was significantly elevated, and the relative expression of the CAR gene was the highest in the CC1 overexpression plus CVB3 group. TNF-α and IL-1β levels increased due to CC1 overexpression and further increased after CVB3 infection. CAR protein expression also changed along with the levels of CC1, SYK, and TNF-α after infection.

CONCLUSION

CC1 may promote CAR expression after CVB3 infection and regulate CAR protein expression by activating the CC1-SYK-TNF-α signaling axis during the infection process.

Activation of CaMKIIδA promotes Ca2+ leak from the sarcoplasmic reticulum in cardiomyocytes of chronic heart failure rats

Activation of the Ca²⁺/calmodulin-dependent protein kinase II isoform δA (CaMKIIδA) disturbs intracellular Ca²⁺ homeostasis in cardiomyocytes during chronic heart failure (CHF). We hypothesized that upregulation of CaMKIIδA in cardiomyocytes might enhance Ca²⁺ leak from the sarcoplasmic reticulum (SR) via activation of phosphorylated ryanodine receptor type 2 (P-RyR2) and decrease Ca²⁺ uptake by inhibition of SR calcium ATPase 2a (SERCA2a). In this study, CHF was induced in rats by ligation of the left anterior descending coronary artery. We found that CHF caused an increase in the expression of CaMKIIδA and P-RyR2 in the left ventricle (LV). The role of CaMKIIδA in regulation of P-RyR2 was elucidated in cardiomyocytes isolated from neonatal rats in vitro. Hypoxia induced upregulation of CaMKIIδA and activation of P-RyR2 in the cardiomyocytes, which both were attenuated by knockdown of CaMKIIδA. Furthermore, we showed that knockdown of CaMKIIδA significantly decreased the Ca²⁺ leak from the SR elicited by hypoxia in the cardiomyocytes. In addition, CHF also induced a downregulation of SERCA2a in the LV of CHF rats. Knockdown of CaMKIIδA normalized hypoxia-induced downregulation of SERCA2a in cardiomyocytes in vitro. The results demonstrate that the inhibition of CaMKIIδA may improve cardiac function by preventing SR Ca²⁺ leak through downregulation of P-RyR2 and upregulation of SERCA2a expression in cardiomyocytes in CHF.

Connexins and Nitric Oxide Inside and Outside Mitochondria: Significance for Cardiac Protection and Adaptation

Irreversible myocardial damage happens in the presence of prolonged and severe ischemia. Several phenomena protect the heart against myocardial infarction and other adverse outcomes of ischemia and reperfusion (IR), namely: hibernation related to stunned myocardium, ischemic preconditioning (IPC), ischemic post-conditioning, and their pharmacological surrogates. Ischemic preconditioning consists in the induction of a brief IR to reduce damage of the tissue caused by prolonged and severe ischemia. Nitric oxide (NO) signaling plays an essential role in IPC. Nitric oxide-sensitive guanylate cyclase/cyclic guanosine-3′,5′-monophosphate (cGMP)-dependent protein kinase type I-signaling pathway protects against the IR injury during myocardial infarction. Mitochondrial ATP-sensitive and Ca²⁺-activated K⁺ channels are involved in NO-mediated signaling in IPC. Independently of the cGMP-mediated induction of NO production, S-nitrosation represents a regulatory molecular mechanism similar to phosphorylation and is essential for IPC. Unlike conditioning phenomena, the mechanistic basis of myocardial stunning and hibernation remains poorly understood. In this review article, we hypothesize that the disruption of electrical syncytium of the myocardium may underly myocardial stunning and hibernation. Considering that the connexins are the building blocks of gap junctions which represent primary structural basis of electrical syncytium, we discuss data on the involvement of connexins into myocardial conditioning, stunning, and hibernation. We also show how NO-mediated signaling is involved in myocardial stunning and hibernation. Connexins represent an essential element of adaptation phenomena of the heart at the level of both the cardio- myocytes and the mitochondria. Nitric oxide targets mitochondrial connexins which may affect electrical syncytium continuum in the heart. Mitochondrial connexins may play an essential role in NO-dependent mechanisms of myocardial adaptation to ischemia.