The Significance of Neuregulin-1/ErbB Expression in Autogenous Vein Grafts in a Diabetic Rat Model:

Neuregulin-1, a potential therapeutic target for cardiac repair

NRG1 (Neuregulin-1) is an effective cardiomyocyte proliferator, secreted and released by endothelial vascular cells, and affects the cardiovascular system. It plays a major role in heart growth, proliferation, differentiation, apoptosis, and other cardiovascular processes. Numerous experiments have shown that NRG1 can repair the heart in the pathophysiology of atherosclerosis, myocardial infarction, ischemia reperfusion, heart failure, cardiomyopathy and other cardiovascular diseases. NRG1 can connect related signaling pathways through the NRG1/ErbB pathway, which form signal cascades to improve the myocardial microenvironment, such as regulating cardiac inflammation, oxidative stress, necrotic apoptosis. Here, we summarize recent research advances on the molecular mechanisms of NRG1, elucidate the contribution of NRG1 to cardiovascular disease, discuss therapeutic approaches targeting NRG1 associated with cardiovascular disease, and highlight areas for future research.

Neuregulin-1β Alleviates Sepsis-Induced Skeletal Muscle Atrophy by Inhibiting Autophagy via AKT/mTOR Signaling Pathway in Rats

BACKGROUND

Several studies have shown that excessive protein degradation is a major cause of skeletal muscle atrophy induced by sepsis, and autophagy is the main pathway participating in protein degradation. However, the role of autophagy in sepsis is still controversial. Previously, we found that neuregulin-1β (NRG-1β) alleviated sepsis-induced diaphragm atrophy through the phosphatidylinositol-3 kinase signaling pathway. Akt/mechanistic target of rapamycin (mTOR) is a classic signaling pathway to regulate autophagy, which maintains intracellular homeostasis. This study aimed to investigate whether NRG-1β could alleviate sepsis-induced skeletal muscle atrophy by regulating autophagy.

METHODS

L6 rat myoblast cells were differentiated using 2% fetal bovine serum into myotubes, which were divided into four groups: Con group treated with normal serum; Sep group treated with septic serum to form a sepsis cell model; septic serum + NRG-1β (SN) group treated with septic serum for 24 h followed by injection with NRG-1β and incubation for another 48 h; and serum+NRG-1β+LY294002 group, in which the PI3K inhibitor LY294002 was added 30 min before NRG-1β, and other treatments were similar to those in SN group. Effects of NRG-1β were also evaluated in vivo using Sprague-Dawley (SD) rats, in which sepsis was induced by cecal ligation and puncture (CLP).

RESULTS

In L6 myotubes treated with septic serum, the expression of autophagy-related proteins UNC-51 like kinase 1, p-Beclin-1, and Beclin-1, and the ratio of LC3B II/I were highly increased, while protein p62 expression was decreased, indicating that autophagy was excessively activated. Moreover, NRG-1 expression was decreased, as detected by confocal immunofluorescence and western blotting. Upon exogenous addition of NRG-1β, autophagy was inhibited by the activation of Akt/mTOR signaling pathway, and cell viability was also increased. These effects disappeared in the presence of LY294002. In SD rats, sepsis was induced by CLP. NRG-1β was shown to inhibit autophagy in these rats via the Akt/mTOR pathway, leading to increased body weight of the septic SD rats and alleviation of atrophy of the tibialis anterior muscle.

CONCLUSION

NRG-1β could alleviate sepsis-induced skeletal muscle atrophy by inhibiting autophagy via the AKT/mTOR signaling pathway.

Programmable dual responsive system reconstructing nerve interaction with small-diameter tissue-engineered vascular grafts and inhibiting intimal hyperplasia in diabetes

Small-diameter tissue-engineered vascular grafts (sdTEVGs) with hyperglycemia resistance have not been constructed. The intimal hyperplasia caused by hyperglycemia remains problem to hinder the patency of sdTEVGs. Here, inspired by bionic regulation of nerve on vascular, we found the released neural exosomes could inhibit the abnormal phenotype transformation of vascular smooth muscle cells (VSMCs). The transformation was a prime culprit causing the intimal hyperplasia of sdTEVGs. To address this concern, sdTEVGs were modified with an on-demand programmable dual-responsive system of ultrathin hydrogels. An external primary Reactive Oxygen Species (ROS)-responsive Netrin-1 system was initially triggered by local inflammation to induce nerve remolding of the sdTEVGs overcoming the difficulty of nerve regeneration under hyperglycemia. Then, the internal secondary ATP-responsive DENND1A (guanine nucleotide exchange factor) system was turned on by the neurotransmitter ATP from the immigrated nerve fibers to stimulate effective release of neural exosomes. The results showed nerve fibers grow into the sdTEVGs in diabetic rats 30 days after transplantation. At day 90, the abnormal VSMCs phenotype was not detected in the sdTEVGs, which maintained long-time patency without intima hyperplasia. Our study provides new insights to construct vascular grafts resisting hyperglycemia damage.

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VSMCs undergo a phenotypic transformation under high glucose, which lead to intimal hyperplasia in sdTEVGs.

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Neural exosomes could inhibit the abnormal phenotype transformation of VSMCs from contractile to synthetic.

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SdTEVGs with on-demand programmable dual responsive system inhibited intimal hyperplasia in diabetes.

Local application of paeonol prevents early restenosis: a study with a rabbit vein graft model

BACKGROUND

Neointimal hyperplasia, which is caused by dysfunction of vascular smooth muscle cells and vascular endothelial cells (VECs), is a foundation for later development of vein grafted occlusion. This study investigates whether neointimal hyperplasia could be prevented by the application of paeonol, a phenolic compound having functions of anti-inflammatory, anti-oxidant, and anti-proliferative.

METHODS

Autologous jugular veins, which engrafted to carotid arteries in rabbits, were enveloped with paeonol or left untreated. After 0, 2, and 3 wk, vein grafts were respectively harvested. Proliferating cell nuclear antigen, vascular cell adhesion molecule l (VCAM-1), and intercellular cell adhesion molecule 1 were assessed with immunohistochemistry and Western blot. VECs apoptosis was also detected with terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling assay.

RESULTS

Paeonol treatment reduced early neointimal hyperplasia by 42%-46% (P < 0.001) and early medial hyperplasia by 18%-22% (P < 0.001) compared with the controls. Immunohistochemical and Western blot results show a significant downregulation of proliferating cell nuclear antigen (P < 0.001) and VCAM-1 (P < 0.001) in paeonol treatment group in the second and third weeks. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling analysis discovered that VECs apoptosis was also reduced by the paeonol treatment in the second and third weeks (P < 0.001).

CONCLUSIONS

Paeonol could prevent vein graft early restenosis by suppressing intimal and medial hyperplasia via inhibition of vascular smooth muscle cells proliferation, VCAM-1 expression, and anti-apoptosis of VECs in grafted veins.