Due to vasculature injury and increased oxygen consumption, the early wound microenvironment is typically in a hypoxic state. We observed enhanced cell migration ability under early short-term hypoxia. CCL2 belongs to the CC chemokine family and was found to be increased in early hypoxic wounds and enriched in the extracellular signal-regulated kinase (ERK)1/2 pathway in our previous study. However, the underlying mechanism through which the CCL2-ERK1/2 pathway regulates wound healing under early short-term hypoxia remains unclear. Activation of epithelial–mesenchymal transition (EMT) is a key process in cancer cell metastasis, during which epithelial cells acquire the characteristics of mesenchymal cells and enhance cell motility and migration ability. However, the relationship between epithelial cell migration and EMT under early short-term hypoxia has yet to be explored.

HaCaT cells were cultured to verify the effect of early short-term hypoxia on migration through cell scratch assays. Lentiviruses with silenced or overexpressed CCL2 were used to explore the relationship between CCL2 and migration under short-term hypoxia. An acute full-thickness cutaneous wound rat model was established with the application of an ERK inhibitor to reveal the hidden role of the ERK1/2 pathway in the early stage of wound healing. The EMT process was verified in all the above experiments through western blotting.

In our study, we found that short-term hypoxia promoted cell migration. Mechanistically, hypoxia promoted cell migration through mediating CCL2. Overexpression of CCL2 via lentivirus promoted cell migration, while silencing CCL2 via lentivirus inhibited cell migration and the production of related downstream proteins. In addition, we found that CCL2 was enriched in the ERK1/2 pathway, and the application of an ERK inhibitor in vivo and in vitro verified the upstream and downstream relationships between the CCL2 pathway and ERK1/2. Western blot results both in vivo and in vitro demonstrated that early short-term hypoxia promotes epidermal cell migration by activating the CCL2-ERK1/2 pathway and EMT during wound healing.

Our work demonstrated that hypoxia in the early stage serves as a stimulus for triggering wound healing through activating the CCL2-ERK1/2 pathway and EMT, which promote epidermal cell migration and accelerate wound closure. These findings provide additional detailed insights into the mechanism of wound healing and new targets for clinical treatment.

To explore the mechanism of Artemisia annua L.（A. annua）in treatment of Mycobacterium abscessus（M. abscessus）infection with aid of network pharmacology and molecular docking.

The active components of A. annua were obtained from the Traditional Chinese Medicine System Pharmacology Database and Analysis Platform（TCMSP）system, and the targets of A. annua were predicted using PharmMapper and SwissTargetPrediction. Targets related to M. abscessus infection were obtained from GeneCards database and OMIM database. After obtaining the common targets of them, a target protein-protein interaction（PPI）network was constructed using the STRING database and Cytoscape software. Then Metascape database was employed to perform Gene Ontology（GO）and Kyoto Encyclopedia of Genes and Genomes（KEGG）enrichment analysis. The main potential active components of A. annua were screened out for molecular docking with the core targets. The extracts of A. annua and the main potential active ingredients screened out were tested in vitro to explore its minimum inhibitory concentration（MIC）, its combined efficacy with common anti-M. abscessus antibiotics in vitro, and its effect on the viability of M. abscessus.

A total of 48 targets of A. annua were found to be involved in the pathogenesis of M. abscessus infection. A total of 6 targets, MMP9, MAPK3, CASP3, IL2, CASP1, and MMP2, were predicted to be the core targets of A. annua in the treatment of this disease. KEGG enrichment analysis showed that A. annua may treat this disease through IL-17 signaling pathway, neutrophil extracellular trap formation, Toll-like receptor signaling pathway, tumor necrosis factor signaling pathway, MAPK signaling pathway and other inflammatory and immune-related signaling pathways. Molecular docking results indicated that A. annua had a high affinity with these core targets. Tamarixetin, artemetin, dihydroartemisinin and Artemisia annua L. were screened to have antibacterial activity against M. abscessus in vitro, with a MIC value of 200, 100, 100 and 100 μg/mL, respectively. After combined with the exacts of A. annua, the MIC value of clarithromycin, azithromycin, amikacin, imipenem, and cefoxitin was all decreased than that of their single use, with a declining multiple ranging from 2 to 8 times.

A. annua may act on M. abscessus infection through multiple targets and multiple pathways. It has antibacterial effect in vitro and shows a synergistic effect with some antibiotics against the bacteria.