Apigenin enhances viability of random skin flaps by activating autophagy

Neuregulin-1, a member of the epidermal growth factor family, mitigates STING-mediated pyroptosis and necroptosis in ischaemic flaps

Background

Ensuring the survival of the distal end of a random flap during hypoperfusion (ischaemia) is difficult in clinical practice. Effective prevention of programmed cell death is a potential strategy for inhibiting ischaemic flap necrosis. The activation of stimulator of interferon genes (STING) pathway promotes inflammation and leads to cell death. The epidermal growth factor family member neuregulin-1 (NRG1) reduces cell death by activating the protein kinase B (AKT) signalling pathway. Moreover, AKT signalling negatively regulates STING activity. We aimed to verify the efficacy of NRG1 injection in protecting against flap necrosis. Additionally, we investigated whether NRG1 effectively enhances ischemic flap survival by inhibiting pyroptosis and necroptosis through STING suppression.

Methods

A random-pattern skin flap model was generated on the backs of C57BL/6 mice. The skin flap survival area was determined. The blood supply and vascular network of the flap was assessed by laser Doppler blood flow analysis. Cluster of differentiation 34 immunohistochemistry (IHC) and haematoxylin and eosin (H&E) staining of the flap sections revealed microvessels. Transcriptome sequencing analysis revealed the mechanism by which NRG1 promotes the survival of ischaemic flaps. The levels of angiogenesis, oxidative stress, necroptosis, pyroptosis and indicators associated with signalling pathways in flaps were examined by IHC, immunofluorescence and Western blotting. Packaging adeno-associated virus (AAV) was used to activate STING in flaps.

Results

NRG1 promoted the survival of ischaemic flaps. An increased subcutaneous vascular network and neovascularization were found in ischaemic flaps after the application of NRG1. Transcriptomic gene ontology enrichment analysis and protein level detection indicated that necroptosis, pyroptosis and STING activity were reduced in the NRG1 group. The phosphorylation of AKT and forkhead box O3a (FOXO3a) were increased after NRG1 treatment. The increased expression of STING in flaps induced by AAV reversed the therapeutic effect of NRG1. The ability of NRG1 to phosphorylate AKT-FOXO3a, inhibit STING and promote flap survival was abolished after the application of the AKT inhibitor MK2206.

Conclusions

NRG1 inhibits pyroptosis and necroptosis by activating the AKT-FOXO3a signalling pathway to suppress STING activation and promote ischaemic flap survival.

Dihydromyricetin regulates KEAP1-Nrf2 pathways to enhance the survival of ischemic flap

In clinical flap practice, there are a lot of studies being done on how to promote the survival of distal random flap necrosis in the hypoxic and ischemic state. As a traditional Chinese medicine, dihydromyricetin (DHM) is crucial in preventing oxidative stress and apoptosis in a number of disorders. In this work, we examined the impact of DHM on the ability to survive of ischemia flaps and looked into its fundamental mechanism. Our results showed that DHM significantly increased the ischemic flaps' survival area, encouraged angiogenesis and blood flow, reduced oxidative stress and apoptosis, and stimulated KEAP1-Nrf2 (Kelch-like ECH-associated protein 1-nuclear factor erythroid 2-related factor) signaling pathways. Adeno-associated virus (AAV) upregulation of KEAP1 expression also negated the favorable effects of DHM on flap survival. By activating KEAP1-Nrf2 signaling pathways, DHM therapy promotes angiogenesis while reducing oxidative stress and apoptosis.

Edaravone promotes viability of random skin flaps via activating PI3K/Akt/mTOR signalling pathway-mediated enhancement of autophagy

Random skin flap transplantation is a commonly used technique. However, ischemia and ischemia-reperfusion injury always impair its therapeutic effectiveness through acclerating oxidative stress, apoptosis and suppressing angiogenesis. To survive, cells rely on mediating autophagy, DNA repair, immunoregulation to resist these cellular injuries. Thus, mediating autophagy may affect the survival of random skin flaps. The edaravone (EDA), a oxygen radicals scavenger, also possesses autophagy mediator potential, we investigated the effects of EDA on skin flap survival and its autophagy-related mechanisms. In vivo, mice were administered EDA or saline intraperitoneally for 7 days postoperatively. We found that EDA ameliorated the viability of random skin flaps, promoted autophagy and angiogenesis, attenuated apoptosis and oxidative stress. In vitro, mouse umbilical vascular endothelial cells (MUVECs) were administered EDA or 3-methyladenine (3-MA, an autophagy inhibitor) or rapacymin (Rapa, an autophagy activator) at the beginning of oxygen glucose deprivation (OGD). We found that EDA promoted cell viability, activated autophagy, enhanced angiogenesis, alleviated apoptosis and oxidative stress. On one hand, 3-MA reversed the effects of EDA on cell viability, oxidative stress and apoptosis via inhibiting autophagy. On the other hand, Rapa had the similar effects of EDA. Furthermore, EDA-induced autophagy was mediated through downregulating PI3K/Akt/mTOR signalling pathway. The findings showed that EDA ameliorated viability of random skin flaps by promoting angiogenesis, suppressing oxidative stress and apoptosis, which may be mediated by autophagic activation through downregulating PI3K/AKT/mTOR signalling pathway.

Rosuvastatin promotes survival of random skin flaps through AMPK-mTOR pathway-induced autophagy

Plastic surgery frequently employs random skin flaps. However, its clinical applicability is constrained by flap necrosis brought on by ischemia-reperfusion damage. Flap survival is aided by rosuvastatin, a naturally occurring flavonoid primarily obtained from plants. In this research, we looked into the processes mediating the effects of rosuvastatin on flap survival. All experimental mice were randomly assigned to three groups: control, rosuvastatin, and 3-methyladenine (3MA) plus rosuvastatin. These groups were, respectively, treated with dimethyl sulfoxide solution, rosuvastatin, and rosuvastatin combined with 3MA. After that, the animals were euthanized so that histology and protein analyses could determine the extent of angiogenesis, pyroptosis, oxidative stress, and autophagy. In addition to lessening tissue edema, rosuvastatin promoted the survival of the skin flap. Rosuvastatin also promoted angiogenesis, reduced oxidative stress, induced autophagy, and reduced pyroptosis. According to the study's findings, rosuvastatin increases angiogenesis, prevents pyroptosis, and reduces oxidative stress by inducing autophagy, which improves the survival rate of random skin flaps.

Berberine promotes the viability of random skin flaps via the PI3K/Akt/eNOS signaling pathway

Random skin flaps are often used in reconstruction operations. However, flap necrosis is still a common postoperative complication. Here, we investigated whether berberine (C₂₀ H₁₉ NO₅ , BBR), a drug with antioxidant activity, improves the survival rate of random flaps. Fifty-four rats were divided into three groups: control, BBR and BBR + _L -NAME groups (_L -NAME, _L -N^G -Nitro-arginine methyl ester). The survival condition and the percentage of survival area of the flaps were evaluated on the seventh day after surgery. After animals were sacrificed, angiogenesis, apoptosis, oxidative stress and inflammation levels were assessed by histological and protein analyses. Our findings suggest that berberine promotes flap survival. The level of angiogenesis increased; the levels of oxidative stress, inflammation and apoptosis decreased; the levels of phosphoinositide 3-kinase (PI3K), phospho-Akt (p-Akt) and phospho-endothelial nitric oxide synthase (p-eNOS) increased in the flap tissue; and _L -NAME reversed the effects of berberine on random skin flaps. Statistical analysis showed that the BBR group results differed significantly from those of the control and the BBR + _L -NAME groups (p < .05). Our results confirm that berberine is an effective drug for significantly improving the survival rate of random skin flaps by promoting angiogenesis, inhibiting inflammation, attenuating oxidative stress, and reducing apoptosis through the PI3K/Akt/eNOS signaling pathway.

The potential application of natural products in cutaneous wound healing: A review of preclinical evidence

Under normal circumstances, wound healing can be summarized as three processes. These include inflammation, proliferation, and remodeling. The vast majority of wounds heal rapidly; however, a large percentage of nonhealing wounds have still not been studied significantly. The factors affecting wound nonhealing are complex and diverse, and identifying an effective solution from nature becomes a key goal of research. This study aimed to highlight and review the mechanisms and targets of natural products (NPs) for treating nonhealing wounds. The results of relevant studies have shown that the effects of NPs are associated with PI3K-AKT, P38MAPK, fibroblast growth factor, MAPK, and ERK signaling pathways and involve tumor growth factor (TNF), vascular endothelial growth factor, TNF-α, interleukin-1β, and expression of other cytokines and proteins. The 25 NPs that contribute to wound healing were systematically summarized by an inductive collation of the six major classes of compounds, including saponins, polyphenols, flavonoids, anthraquinones, polysaccharides, and others, which will further direct the attention to the active components of NPs and provide research ideas for further development of new products for wound healing.