PTT/ PDT-induced microbial apoptosis and wound healing depend on immune activation and macrophage phenotype transformation.

Antibiotics show unsuccessful application in biofilm destruction, which induce chronic infections and emergence of antibiotic resistant bacteria. Photodynamic therapy (PDT) and photothermal therapy (PTT), as widely accepted antimicrobial tools of phototherapy, could effectively activate the immune system and promote the proliferation of wound tissue, thus becoming the most promising therapeutic strategy to replace antibiotics and avoid drug-resistant strains. However, there is no consensus on whether antibacterial and wound healing achieved by PDT/PTT depend not only on the cytotoxic effect of the treatment itself, but also on the activation of host immune system. In this study, CaSiO3-ClO2@PDA-ICG nanoparticles (CCPI NPs) were designed as PDT/PTT antimicrobial model material. With the comparison of healing effect between wide-type mice and severely immunodeficient (C-NKG) mice, the dependence of PDT/PTT-induced microbial apoptosis and wound healing on immune activation and macrophage phenotype transformation was explored and verified. Furthermore, the induced phenotypic transformation of macrophages during PDT/PTT treatment was demonstrated to play crucial role in the improvement of epithelial-mesenchymal transformation (EMT). In summary, this study represents great significance for further identifying the role of immune system activation in antibacterial phototherapy and developing new treatment strategies for biofilm-infected wound healing. STATEMENT OF SIGNIFICANCE: A PDT/PTT combination therapy model nanoparticle was established for biofilm-infected wounds. Both microbial apoptosis and wound healing achieved by PDT/PTT combination therapy were highly dependent on the activated immune system, especially the M2 macrophage phenotype. PDT/PTT could promote the polarization of monocytes to the phenotype of M2 macrophages, which promotes EMT behavior of the tissue at the edge of the wound through the secretion of TGF-ß1, thus accelerating wound healing.

Three-dimension chitosan hydrogel loading melanin composite nanoparticles for wound healing by anti-bacteria, immune activation and macrophage autophagy promotion.

Application of Combined photodynamic therapy (PDT) and photothermal therapy (PTT) has become one of the most promising strategy to replace antibiotics and avoid the epidemic of drug-resistant strains during wound healing. However, high amount of reactive oxygen species (ROS) and high temperature cause severe stress response to normal tissues, leading to potential risks of wound healing. Herein, a three-dimension chitosan hydrogel melanin-glycine-C60 nanoparticles (MGC NPs) were prepared to realized effective anti-bacterial activity, immune activation and macrophage autophagy promotion in three-dimensional wound space without triggering stress response. MGC NP is a composite polymer material composed of natural melanin polymer, oligopeptide and carbon-based material, which showed excellent biological safety. By regulating the peptide length between melanin and C60 and nanoparticle content, a high ROS/heat environment at the upper wound site and a low ROS/heat environment at the lower region adjacent to the wound tissue were established to obtain a three-dimension hydrogel with precise PDT and PTT efficiency in different regions. Highly effective PDT/PTT was used to kill microorganisms in upper region, thus providing a barrier to reduce microbial infection. Mild PDT/PTT in lower region promoted the polarization of M1 macrophage to M2 macrophage and activated autophagy of M2 macrophages, regulating the immune microenvironment and promoting wound repair. In conclusion, the novel three-dimensional PDT/PTT therapy based on natural macromolecules proposed in this study accelerates wound healing through dual pathways on the premise of avoiding wound stress response, which is of great significance for the development of clinical strategies for phototherapy.

Hui Medicine Moxibustion Promotes the Absorption of Lumbar Disc Herniation and the Recovery of Motor Function in Rats through Fas/FasL Signaling Pathway.

Objectives: To study the resorption of the herniated lumbar disc (RHLD) and its mechanism in the SD rats of lumbar intervertebral disc herniation treated with Hui medicine moxibustion (HMM). Methods: Forty SD rats were randomly divided into four groups, normal group, lumbar disc herniation (LDH) group, HMM group, and antagonist (HMM+Met12) group, with 10 rats in each group. The rat model of LDH was prepared with the method of lumbar epidural emplacement of the caudal intervertebral disc. In the HMM group and HMM+Met12 groups, 4 weeks after modeling, HMM therapy was performed in the lumbar spine for 3 months with 1 time per day and 20 min each time, the samples were collected 8 weeks after the treatment. The histological degeneration was observed through HE staining, and the neovascularization of intervertebral disc tissues was detected by the expression of CD34 and vascular endothelial growth factor (VEGF). The apoptosis of nucleus pulpous cells was detected by TUNEL assay, and the activity of caspase-3, -8, and -9 and extracellular matrix enzymes was detected by western blotting. Results: HMM treatment significantly improved the behavioral ability of rats with LDH surgery. The morphological structure was obviously destroyed in the LDH group, but disc structure was significantly repaired in the HMM group, and mild structure alterations were observed in the HMM+Met12 group. Higher levels of CD34 and VEGF were detected in the HMM group indicating that neovascularization is formed. The expression level of FasL was significantly increased in the HMM group. The protein expression levels of cleaved-caspase-3, cleaved-caspase-8, and cleaved-caspase-9 in nucleus pulposus (NP) tissues were also elevated when treated with HMM, and the TUNEL staining showed the same results. The protein expression levels of matrix metalloproteinases- (MMP-) 1, MMP-2, MMP-3, MMP-13, and ADAMTS-4 were markedly promoted in the HMM group. Met12, a small peptide antagonist of FasL, significantly reduced the effects of HMM. Conclusion: HMM can promote the formation of neovascularization of lumbar intervertebral disc, support the apoptosis of NP cells through Fas/FasL signaling, and regulate the degradation of extracellular matrix enzyme, which then accelerates the absorption of lumbar intervertebral disc herniation and the recovery of motor function in rats.