Targeting Microtubules for Wound Repair

In Vitro/Vivo Mechanisms of Antibacterial Peptide NZ2114 against Staphylococcus pseudintermedius and Its Biofilms

Staphylococcus pseudintermedius is an opportunistic pathogen commonly found in canines, and has garnered escalating interest due to its potential for zoonotic transmission and increasing antimicrobial resistance. However, the excessive use of antibiotics and the characteristic of S. pseudintermedius forming biofilms make treatment challenging. In this study, the in vivo and in vitro antimicrobial activity and mechanisms of action of NZ2114, a plectasin-derived peptide, against S. pseudintermedius were investigated. NZ2114 exhibited potent antibacterial activity towards S. pseudintermedius (minimum inhibitory concentration, MIC = 0.23 μM) with a lower probability of inducing drug-resistant mutations and efficient bactericidal action, which was superior to those of mopirucin (MIC = 0.25-0.5 μM) and lincomycin (MIC = 4.34-69.41 μM). The results of electron microscopy and flow cytometry showed that NZ2114 disrupted S. pseudintermedius' cell membrane, resulting in cellular content leakage, cytoplasmic membrane shrinkage, and, eventually, cell death. The intracellular ROS activity and Alamar Blue detection showed that NZ2114 interferes with intracellular metabolic processes. In addition, NZ2114 effectively inhibits biofilm formation, and confocal laser scanning microscopy further revealed its antibacterial and anti-biofilm activity (biofilm thickness reduced to 6.90-17.70 μm). The in vivo therapy of NZ2114 in a mouse pyoderma model showed that it was better than lincomycin in effectively decreasing the number of skin bacteria, alleviating histological damage, and reducing the skin damage area. These results demonstrated that NZ2114 may be a promising antibacterial candidate against S. pseudintermedius infections.

Transcriptome analysis of peripheral blood of Schistosoma mansoni infected children from the Albert Nile region in Uganda reveals genes implicated in fibrosis pathology

Over 290 million people are infected by schistosomes worldwide. Schistosomiasis control efforts focus on mass drug treatment with praziquantel (PZQ), a drug that kills the adult worm of all Schistosoma species. Nonetheless, re-infections have continued to be detected in endemic areas with individuals living in the same area presenting with varying infection intensities. Our objective was to characterize the transcriptome profiles in peripheral blood of children between 10-15 years with varying intensities of Schistosoma mansoni infection living along the Albert Nile in Uganda. RNA extracted from peripheral blood collected from 44 S. mansoni infected (34 high and 10 low by circulating anodic antigen [CAA] level) and 20 uninfected children was sequenced using Illumina NovaSeq S4 and the reads aligned to the GRCh38 human genome. Differential gene expression analysis was done using DESeq2. Principal component analysis revealed clustering of gene expression by gender when S. mansoni infected children were compared with uninfected children. In addition, we identified 14 DEGs between S. mansoni infected and uninfected individuals, 56 DEGs between children with high infection intensity and uninfected individuals, 33 DEGs between those with high infection intensity and low infection intensity and no DEGs between those with low infection and uninfected individuals. We also observed upregulation and downregulation of some DEGs that are associated with fibrosis and its regulation. These data suggest expression of fibrosis associated genes as well as genes that regulate fibrosis in S. mansoni infection. The relatively few significant DEGS observed in children with schistosomiasis suggests that chronic S. mansoni infection is a stealth infection that does not stimulate a strong immune response.

Mitophagy associated self-degradation of phosphorylated MAP4 guarantees the migration and proliferation responses of keratinocytes to hypoxia

Our previous study has announced that phosphorylated microtubule-associated protein 4 (p-MAP4) accelerated keratinocytes migration and proliferation under hypoxia through depolymerizing microtubules. However, p-MAP4 should exhibit inhibitory effects on wound healing, for it also impaired mitochondria. Thus, figuring out the outcome of p-MAP4 after it impaired mitochondria and how the outcome influenced wound healing were far-reaching significance. Herein, the results revealed that p-MAP4 might undergo self-degradation through autophagy in hypoxic keratinocytes. Next, p-MAP4 activated mitophagy which was unobstructed and was also the principal pathway of its self-degradation triggered by hypoxia. Moreover, both Bcl-2 homology 3 (BH3) and LC3 interacting region (LIR) domains had been verified in MAP4, and they endowed MAP4 with the capability to synchronously function as a mitophagy initiator and a mitophagy substrate receptor. And, mutating any one of them ruined hypoxia-induced self-degradation of p-MAP4, resulting in destroyed proliferation and migration responses of keratinocytes to hypoxia. Our findings unviewed that p-MAP4 experienced mitophagy-associated self-degradation through utilizing its BH3 and LIR domains under hypoxia. As a result, the mitophagy-associated self-degradation of p-MAP4 guaranteed the migration and proliferation responses of keratinocytes to hypoxia. Together, this research provided a bran-new pattern of proteins in regulating wound healing, and offered a new direction for intervening wound healing.

Gut homeostasis, injury, and healing: New therapeutic targets

The integrity of the gastrointestinal mucosa plays a crucial role in gut homeostasis, which depends upon the balance between mucosal injury by destructive factors and healing via protective factors. The persistence of noxious agents such as acid, pepsin, nonsteroidal anti-inflammatory drugs, or Helicobacter pylori breaks down the mucosal barrier and injury occurs. Depending upon the size and site of the wound, it is healed by complex and overlapping processes involving membrane resealing, cell spreading, purse-string contraction, restitution, differentiation, angiogenesis, and vasculogenesis, each modulated by extracellular regulators. Unfortunately, the gut does not always heal, leading to such pathology as peptic ulcers or inflammatory bowel disease. Currently available therapeutics such as proton pump inhibitors, histamine-2 receptor antagonists, sucralfate, 5-aminosalicylate, antibiotics, corticosteroids, and immunosuppressants all attempt to minimize or reduce injury to the gastrointestinal tract. More recent studies have focused on improving mucosal defense or directly promoting mucosal repair. Many investigations have sought to enhance mucosal defense by stimulating mucus secretion, mucosal blood flow, or tight junction function. Conversely, new attempts to directly promote mucosal repair target proteins that modulate cytoskeleton dynamics such as tubulin, talin, Ehm², filamin-a, gelsolin, and flightless I or that proteins regulate focal adhesions dynamics such as focal adhesion kinase. This article summarizes the pathobiology of gastrointestinal mucosal healing and reviews potential new therapeutic targets.

Zebrafish as a Model System to Study the Mechanism of Cutaneous Wound Healing and Drug Discovery: Advantages and Challenges

In humans, cutaneous wounds may heal without scars during embryogenesis. However, in the adult phase, the similar wound may undergo a few events such as homeostasis, blood clotting, inflammation, vascularization, and the formation of granulation tissue, which may leave a scar at the injury site. In consideration of this, research evolves daily to improve the healing mechanism in which the wound may heal without scarring. In regard to this, zebrafish (Danio rerio) serves as an ideal model to study the underlying signaling mechanism of wound healing. This is an important factor in determining a relevant drug formulation for wound healing. This review scrutinizes the biology of zebrafish and how this favors the cutaneous wound healing relevant to the in vivo evidence. This review aimed to provide the current insights on drug discovery for cutaneous wound healing based on the zebrafish model. The advantages and challenges in utilizing the zebrafish model for cutaneous wound healing are discussed in this review. This review is expected to provide an idea to formulate an appropriate drug for cutaneous wound healing relevant to the underlying signaling mechanism. Therefore, this narrative review recapitulates current evidence from in vivo studies on the cutaneous wound healing mechanism, which favours the discovery of new drugs. This article concludes with the need for zebrafish as an investigation model for biomedical research in the future to ensure that drug repositions are well suited for human skin.

Nanoparticle mediated RNA delivery for wound healing

Wound healing is a complicated physiological process that comprises various steps, including hemostasis, inflammation, proliferation, and remodeling. The wound healing process is significantly affected by coexisting disease states such as diabetes, immunosuppression, or vascular disease. It can also be impacted by age, repeated injury, or hypertrophic scarring. These comorbidities can affect the rate of wound closure, the quality of wound closure, and tissues' function at the affected sites. There are limited options to improve the rate or quality of wound healing, creating a significant unmet need. Advances in nucleic acid research and the human genome project have developed potential novel approaches to address these outstanding requirements. In particular, the use of microRNA, short hairpin RNA, and silencing RNA is unique in their abilities as key regulators within the physiologic machinery of the cell. Although this innovative therapeutic approach using ribonucleic acid (RNA) is an attractive approach, the application as a therapeutic remains a challenge due to site-specific delivery, off-target effects, and RNA degradation obstacles. An ideal delivery system is essential for successful gene delivery. An ideal delivery system should result in high bioactivity, inhibit rapid dilution, controlled release, allow specific activation timings facilitating physiological stability, and minimize multiple dosages. Currently, these goals can be achieved by inorganic nanoparticle (NP) (e.g., cerium oxide, gold, silica, etc.) based delivery systems. This review focuses on providing insight into the preeminent research carried out on various RNAs and their delivery through NPs for effective wound healing. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

Identification of the Potential Biomarkers Involved in the Human Oral Mucosal Wound Healing: A Bioinformatic Study

Objective. To identify the key genetic and epigenetic mechanisms involved in the wound healing process after injury of the oral mucosa. Materials and Methods. Gene expression profiling datasets pertaining to rapid wound healing of oral mucosa were identified using the Gene Expression Omnibus (GEO) database. Differential gene expression analysis was performed to identify differentially expressed genes (DEGs) during oral mucosal wound healing. Next, functional enrichment analysis was performed to identify the biological processes (BPs) and signaling pathways relevant to these DEGs. A protein-protein interaction (PPI) network was constructed to identify hub DEGs. Interaction networks were constructed for both miRNA-target DEGs and DEGs-transcription factors. A DEGs-chemical compound interaction network and a miRNA-small molecular interaction network were also constructed. Results. DEGs were found significantly enriched in several signaling pathways including arachidonic acid metabolism, cell cycle, p53, and ECM-receptor interaction. Hub genes, GABARAPL1, GABARAPL2, HDAC5, MAP1LC3A, AURKA, and PLK1, were identified via PPI network analysis. Two miRNAs, miR-34a-5p and miR-335-5p, were identified as pivotal players in the miRNA-target DEGs network. Four transcription factors FOS, PLAU, BCL6, and RORA were found to play key roles in the TFs-DEGs interaction network. Several chemical compounds including Valproic acid, Doxorubicin, Nickel, and tretinoin and small molecular drugs including atorvastatin, 17β-estradiol, curcumin, and vitamin D3 were noted to influence oral mucosa regeneration by regulating the expression of healing-associated DEGs/miRNAs. Conclusion. Genetic and epigenetic mechanisms and specific drugs were identified as significant molecular mechanisms and entities relevant to oral mucosal healing. These may be valuable potential targets for experimental research.

MAP4 regulates Tctex-1 and promotes the migration of epidermal cells in hypoxia

After acute wound formation, the oxygen supply is reduced, which results in the formation of an acute hypoxic microenvironment; whether this hypoxic microenvironment enhances epidermal cell migration and the underlying regulatory molecular mechanism of this effect are unclear. In this study, HaCaT cells were maintained under hypoxic (1% oxygen) or normoxic conditions. Methods including immunofluorescence staining, wound scratch assays, transwell assays, Western blotting and high- and low-expression lentiviral vector transfection were utilized to observe the changes in cell migration, microtubule dynamics and the expression levels of microtubule-associated protein (MAP) 4 and the light chain protein DYNLT1 (Tctex-1). The possible mechanisms were studied and discussed. The results showed that epidermal cell migration was enhanced during early hypoxia. Further experiments revealed that MAP4 regulates microtubule dynamics and promotes epidermal cell migration through Tctex-1. MAP4 and Tctex-1 play important roles in regulating the migration of epidermal cells under hypoxia. This evidence will provide a basis for further revealing the cellular and molecular mechanisms of local wound hypoxia and for promoting wound healing.

Identification of Trombospondin-1 as a Novel Amelogenin Interactor by Functional Proteomics

Amelogenins are a set of low molecular-weight enamel proteins belonging to a group of extracellular matrix (ECM) proteins with a key role in tooth enamel development and in other regeneration processes, such as wound healing and angiogenesis. Since only few data are actually available to unravel amelogenin mechanism of action in chronic skin healing restoration, we moved to the full characterization of the human amelogenin isoform 2 interactome in the secretome and lysate of Human Umbilical Vein Endothelial cells (HUVEC), using a functional proteomic approach. Trombospondin-1 has been identified as a novel and interesting partner of human amelogenin isoform 2 and their direct binding has been validated thought biophysical orthogonal approaches.