Abstract
Photodynamic therapy (PDT) is a promising new method to eliminate microbial infection and promote wound healing. Its effectiveness has been confirmed by some studies; however, the mechanisms of PDT in wound healing remain obscure. We used mouse skin wounds infected with Pseudomonas aeruginosa as a research object to explore the therapeutic effects and mechanisms of 5-aminolevulinic acid photodynamic therapy (ALA-PDT). ALA-PDT treatment significantly reduced the load of P. aeruginosa in the wound and surrounding tissues and promoted the healing of skin wounds in mice. Hematoxylin-eosin (HE) and Sirius red staining showed that ALA-PDT promoted granulation tissue formation, angiogenesis, and collagen regeneration and remodeling. After ALA-PDT treatment, the expression of inflammatory factors (TNF-α and IL-1β) first increased and then decreased, while the secretion of growth factors (TGF-β-1 and VEGF) increased gradually after treatment. Furthermore, ALA-PDT affected the polarization state of macrophages, activating and promoting macrophages from an M1 to an M2 phenotype. In conclusion, ALA-PDT can not only kill bacteria but also promote wound healing by regulating inflammatory factors, collagen remodeling and macrophages. This study further clarifies the mechanism of PDT in the healing of infectious skin wounds and provides further experimental evidence for its clinical treatment of skin wounds infected by P. aeruginosa.
Highlights
Skin wounds are a common refractory disease in dermatology and occur in conjunction with microbial infection
The results showed that aminolevulinic acid photodynamic therapy (ALA-Photodynamic therapy (PDT)) can kill bacteria and promote wound healing by regulating inflammatory factors, collagen remodeling and macrophages
To investigate the antibacterial effect of Aminolevulinic acid (ALA)-PDT, we detected the amount of P. aeruginosa on the wounds before treatment and on the 1st, 3rd, 7th, and 14th days after different treatments
Summary
Skin wounds are a common refractory disease in dermatology and occur in conjunction with microbial infection. The treatment of skin wounds usually includes systemic antibiotics, localized treatment with conventional clinical dressings, irrigation, negative pressure drainage, and surgical operation. These treatments used to address skin wounds are always time-consuming and expensive. There have been increasing reports of Pseudomonas aeruginosa infections resulting from skin wounds. P. aeruginosa is both highly resistant and naturally unsusceptible to many antibiotics and tends to form biofilms on infected surfaces. Photodynamic therapy (PDT) has been shown to be a very successful therapy in clinical practice and is widely used in the treatment of certain skin diseases, such as acne, viral warts, and skin
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