Pivotal role for alpha1-antichymotrypsin in skin repair

α1-Antichymotrypsin (α1-ACT) is a specific inhibitor of leukocyte-derived chymotrypsin-like proteases with largely unknown functions in tissue repair. By examining human and murine skin wounds, we showed that following mechanical injury the physiological repair response is associated with an acute phase response of α1-ACT and the mouse homologue Spi-2, respectively. In both species, attenuated α1-ACT/Spi-2 activity and gene expression at the local wound site was associated with severe wound healing defects. Topical application of recombinant α1-ACT to wounds of diabetic mice rescued the impaired healing phenotype. LC-MS analysis of α1-ACT cleavage fragments identified a novel cleavage site within the reactive center loop and showed that neutrophil elastase was the predominant protease involved in unusual α1-ACT cleavage and inactivation in nonhealing human wounds. These results reveal critical functions for locally acting α1-ACT in the acute phase response following skin injury, provide mechanistic insight into its function during the repair response, and raise novel perspectives for its potential therapeutic value in inflammation-mediated tissue damage.     

Enhanced epithelial-mesenchymal transition-like phenotype in N-acetylglucosaminyltransferase V transgenic mouse skin promotes wound healing

N-Acetylglucosaminyltransferase V (GnT-V) catalyzes the β1,6 branching of N-acetylglucosamine on N-glycans. GnT-V expression is elevated during malignant transformation in various types of cancer. However, the mechanism by which GnT-V promotes cancer progression is unclear. To characterize the biological significance of GnT-V, we established GnT-V transgenic (Tg) mice, in which GnT-V is regulated by a β-actin promoter. No spontaneous cancer was detected in any organs of the GnT-V Tg mice. However, GnT-V expression was up-regulated in GnT-V Tg mouse skin, and cultured keratinocytes derived from these mice showed enhanced migration, which was associated with changes in E-cadherin localization and epithelial-mesenchymal transition (EMT). Further, EMT-associated factors snail, twist, and N-cadherin were up-regulated, and cutaneous wound healing was accelerated in vivo. We further investigated the detailed mechanisms of EMT by assessing EGF signaling and found up-regulated EGF receptor signaling in GnT-V Tg mouse keratinocytes. These findings indicate that GnT-V overexpression promotes EMT and keratinocyte migration in part through enhanced EGF receptor signaling.     

Mallotus philippinensis bark extracts promote preferential migration of mesenchymal stem cells and improve wound healing in mice

In the present study, we report the effects of the ethanol extract from Mallotus philippinensis bark (EMPB) on mesenchymal stem cell (MSC) proliferation, migration, and wound healing in vitro and in a mouse model. Chemotaxis assays demonstrated that EMPB acted an MSC chemoattractant and that the main chemotactic activity of EMPB may be due to the effects of cinnamtannin B-1. Flow cytometric analysis of peripheral blood mononuclear cells in EMPB-injected mice indicated that EMPB enhanced the mobilization of endogenous MSCs into blood circulation. Bioluminescent whole-animal imaging of luciferase-expressing MSCs revealed that EMPB augmented the homing of MSCs to wounds. In addition, the efficacy of EMPB on migration of MSCs was higher than that of other skin cell types, and EMPB treatment improved of wound healing in a diabetic mouse model. The histopathological characteristics demonstrated that the effects of EMPB treatment resembled MSC-induced tissue repair. Taken together, these results suggested that EMPB activated the mobilization and homing of MSCs to wounds and that enhancement of MSC migration may improve wound healing.     

负压封闭引流对兔颅骨外露创面愈合效果的实验研究

目的:探讨负压封闭引流技术(VSD)对兔颅骨外露缺损创面愈合的治疗效果。方法:选取成年新西兰大白兔76只,平均分为四组并建立兔颅骨外露实验模型。其中,A组(19只):于兔颅骨上方制作直径为2.0cm的圆形创面,保留骨膜,采用-120mmHg负压引流和常规换药治疗;B组(19只):实验动物处理同A组,仅采用常规换药治疗;C组(19只):在兔颅骨上制作直径2.0cm的圆形创面,剔除骨膜,治疗方法同A组;D组(19只):实验动物处理同C组,治疗方法同B组。每组各抽取10只,观察创面愈合率和创面愈合时间;其余9只分别在第7天、10天、20天、30天进行取材检测,分析疗效机制。结果:A组创面愈合时间为19.40±1.65天,B组为24.00±2.31天;C组为25.40±4.43天,D组为30.00±5.50天。运用VSD治疗和常规治疗创面愈合时间比较有统计学意义(P0.05)。结论:VSD治疗兔骨外露缺损创面能有效缩短创面愈合时间,促进血管再生,胶原蛋白合成。     

Doxycycline Inhibits Polarization of Macrophages to the Proangiogenic M2-type and Subsequent Neovascularization

Macrophages occur along a continuum of functional states between M1-type polarized macrophages with antiangiogenic and antitumor activity and M2-type polarized macrophages, which have been implicated to promote angiogenesis and tumor growth. Proangiogenic M2-type macrophages promote various pathologic conditions, including choroidal neovascularization in models of neovascular age-related macular degeneration, or certain cancers, such as glioblastoma multiforme. Thus, a potential novel therapeutic approach to target pathological angiogenesis in these conditions would be to inhibit the polarization of macrophages toward the proangiogenic M2-type. However, no pharmacological inhibitors of M2-type macrophage polarization have been identified yet. Here we performed an unbiased pharmacological and small chemical screen to identify drugs that inhibit proangiogenic M2-type macrophage polarization and block pathologic macrophage-driven neovascularization. We identified the well tolerated and commonly used antibiotic doxycycline as a potent inhibitor of M2-type polarization of macrophages. Doxycycline inhibited, in a dose-dependent manner, M2-type polarization of human and bone marrow-derived mouse macrophages without affecting cell viability. Furthermore, doxycycline inhibited M2-type macrophage polarization and subsequent neovascularization in vivo in a laser injury model of choroidal neovascularization. Thus, doxycycline could be used to enhance current antiangiogenic treatment approaches in various conditions that are promoted by proangiogenic M2-type macrophages, including neovascular age-related macular degeneration and certain cancers.     

In vitro study of the impact of mechanical tension on the dermal fibroblast phenotype in the context of skin wound healing

Skin wound healing is finely regulated by both matrix synthesis and degradation which are governed by dermal fibroblast activity. Actually, fibroblasts synthesize numerous extracellular matrix proteins (i.e., collagens), remodeling enzymes and their inhibitors. Moreover, they differentiate into myofibroblasts and are able to develop endogenous forces at the wound site. Such forces are crucial during skin wound healing and have been widely investigated. However, few studies have focused on the effect of exogenous mechanical tension on the dermal fibroblast phenotype, which is the objective of the present paper. To this end, an exogenous, defined, cyclic and uniaxial mechanical strain was applied to fibroblasts cultured as scratch-wounded monolayers. Results showed that fibroblasts? response was characterized by both an increase in procollagen type-I and TIMP-1 synthesis, and a decrease in MMP-1 synthesis. The monitoring of scratch-wounded monolayers did not show any decrease in kinetics of the filling up when mechanical tension was applied. Additional results obtained with proliferating fibroblasts and confluent monolayer indicated that mechanical tension-induced response of fibroblasts depends on their culture conditions. In conclusion, mechanical tension leads to the differentiation of dermal fibroblasts and may increase their wound-healing capacities. So, the exogenous uniaxial and cyclic mechanical tension reported in the present study may be considered in order to improve skin wound healing.     

Prevalence,antimicrobial resistance profile,and characterization of multi-drug resistant bacteria from various infected wounds in North Egypt

Multi-drug resistant (MDR) bacteria associated with wounds are extremely escalating. This study aims to survey different wounds in Alexandria hospitals, North Egypt, to explore the prevalence and characteristics of MDR bacteria for future utilization in antibacterial wound dressing designs. Among various bacterial isolates, we determined 22 MDR bacteria could resist different classes of antibiotics. The collected samples exhibited the prevalence of mono-bacterial infections (60%), while 40% included poly-bacterial species due to previous antibiotic administration. Moreover, Gram-negative bacteria showed dominance with a ratio of 63.6%, while Gram-positive bacteria reported 36.4%. Subsequently, the five most virulent bacteria were identified following the molecular approach by 16S rRNA and physiological properties using the VITEK 2 automated system. They were deposited in GenBank as Staphylococcus haemolyticus MST1 ({"type":"entrez-nucleotide","attrs":{"text":"KY550377","term_id":"1304487819","term_text":"KY550377"}}KY550377), Pseudomonas aeruginosa MST2 ({"type":"entrez-nucleotide","attrs":{"text":"KY550378","term_id":"1304487820","term_text":"KY550378"}}KY550378), Klebsiella pneumoniae MST3 ({"type":"entrez-nucleotide","attrs":{"text":"KY550379","term_id":"1304487821","term_text":"KY550379"}}KY550379), Escherichia coli MST4 ({"type":"entrez-nucleotide","attrs":{"text":"KY550380","term_id":"1304487822","term_text":"KY550380"}}KY550380), and Escherichia coli MST5 ({"type":"entrez-nucleotide","attrs":{"text":"KY550381","term_id":"1304487823","term_text":"KY550381"}}KY550381). In terms of isolation source, S. haemolyticus MST1 was isolated from a traumatic wound, while P. aeruginosa MST2 and E. coli MST4 were procured from hernia surgical wounds, and K. pneumoniae MST3 and E. coli MST5 were obtained from diabetic foot ulcers. Antibiotic sensitivity tests exposed that K. pneumoniae MST3, E. coli MST4, and E. coli MST5 are extended-spectrum β-lactamases (ESBLs) bacteria. Moreover, S. haemolyticus MST1 belongs to the methicillin-resistant coagulase-negative staphylococcus (MRCoNS), whereas P. aeruginosa MST2 exhibited resistance to common empirical bactericidal antibiotics. Overall, the study provides new insights into the prevalent MDR bacteria in Egypt for further use as specific models in formulating antibacterial wound dressings.