Epithelial-mesenchymal transition (EMT) describes the global process by which stationary epithelial cells undergo phenotypic changes, including loss of cell-cell adhesion and apical-basal polarity, and acquire mesenchymal characteristics which confer migratory capacity. EMT and its converse, MET (mesenchymal-to-epithelial transition), are integral stages of many physiologic processes, and as such are tightly coordinated by a host of molecular regulators. Converging lines of evidence have identified EMT as a component of cutaneous wound healing, during which otherwise stationary keratinocytes - the resident skin epithelial cells - migrate across the wound bed to restore the epidermal barrier. Moreover, EMT also plays a role in the development of scarring and fibrosis, as the matrix-producing myofibroblast arises from cells of epithelial lineage in response to injury but is pathologically sustained instead of undergoing MET or apoptosis. In this review, we summarize the role of EMT in physiologic repair and pathologic fibrosis of tissues and organs. We conclude that further investigation into the contribution of EMT to the impaired repair of fibrotic wounds may identify components of EMT signaling as common therapeutic targets for impaired healing in many tissues.

Probiotics are beneficial microorganisms, known to exert numerous positive effects on human health, primarily in the battle against pathogens. Probiotics have been associated with improved healing of intestinal ulcers, and healing of infected cutaneous wounds. This article reviews the latest findings on probiotics related to their pro-healing properties on gut epithelium and skin. Proven mechanisms by which probiotic bacteria exert their beneficial effects include direct killing of pathogens, competitive displacement of pathogenic bacteria, reinforcement of epithelial barrier, induction of fibroblasts, and epithelial cells' migration and function. Beneficial immunomodulatory effects of probiotics relate to modulation and activation of intraepithelial lymphocytes, natural killer cells, and macrophages through induced production of cytokines. Systemic effects of beneficial bacteria and link between gut microbiota, immune system, and cutaneous health through gut-brain-skin axes are discussed as well. In light of growing antibiotic resistance of pathogens, antibiotic use is becoming less effective in treating cutaneous and systemic infections. This review points to a new perspective and therapeutic potential of beneficial probiotic species as a safe alternative approach for treatment of patients affected by wound healing disorders and cutaneous infections.

Perforin‐2 (P‐2) is a recently described antimicrobial protein with unique properties to kill intracellular bacteria. We investigated P‐2 expression pattern and cellular distribution in human skin and its importance in restoration of barrier function during wound healing process and infection with the common wound pathogen Staphylococcus aureus. We describe a novel approach for the measurement of P‐2 mRNA within individual skin cells using an amplified fluorescence in situ hybridization (FISH) technique. The unique aspect of this approach is simultaneous detection of P‐2 mRNA in combination with immune‐phenotyping for cell surface proteins using fluorochrome‐conjugated antibodies. We detected P‐2 transcript in both hematopoietic (CD45+) and non‐hematopoietic (CD45−) cutaneous cell populations, confirming the P‐2 expression in both professional and non‐professional phagocytes. Furthermore, we found an induction of P‐2 during wound healing. P‐2 overexpression resulted in a reduction of intracellular S. aureus, while infection of human wounds by this pathogen resulted in P‐2 suppression, revealing a novel mechanism by which S. aureus may escape cutaneous immunity to cause persistent wound infections.

Photodocumentation (medical photography) is an invaluable tool for clinical documentation, monitoring treatment progress, teleconsultation, research, publication and education. In an era of smartphones and tablets, there are now more ways than ever before to take clinical photos. Despite this, studies show there is a paucity of ethnic skin images in the research setting and core dermatology educational resources. 1 Therefore, there is a need for both standardization in medical photography to ensure high-quality images and to provide quality photographs across diverse skin types.A significant proportion of dermatologists report insufficient exposure to Fitzpatrick skin types IV-VI or education on ethnic skin during residency training and as a result, lack confidence in diagnosing and treating skin disease in these patients. 1,2 This is an important consideration, since dermatologic diseases can vary in prevalence and presentation in different race and ethnic groups. Notably, atopic dermatitis is reported to have a higher prevalence in African American and Asian patients and may lack classic findings in white skin such as obvious erythema. 3 In Asian patients, it may present with clearer demarcation of lesions, scaling, and lichenification, while in African American patients it may appear more purple, brown, or gray and be associated with post-inflammatory hyper or hypopigmentation. 4,5 To correct disparities in dermatologic education and educational resources, dermatologists must advocate for more inclusivity in photodocumentation of dark and ethnic skin. In this article, we will discuss important terms and concepts in the context of medical photography, techniques to take high-quality clinical photographs of various Fitzpatrick skin types with different levels of equipment, and special considerations when photographing skin of color in the pediatric population. | E XP OSUREThe exposure of a photograph dictates photographic brightness and is determined by 3 main features: aperture (f-stop; lower number increases exposure), shutter speed (faster speed decreases exposure), and ISO (light sensitivity, increased value promotes brightness).

Perforin-2 (P-2) is an antimicrobial protein with unique properties to kill intracellular bacteria. Gamma delta (GD) T cells, as the major T cell population in epithelial tissues, play a central role in protective and pathogenic immune responses in the skin. However, the tissue-specific mechanisms that control the innate immune response and the effector functions of GD T cells, especially the cross-talk with commensal organisms, are not very well understood. We hypothesized that the most prevalent skin commensal microorganism, Staphylococcus epidermidis, may play a role in regulating GD T cellmediated cutaneous responses. We analyzed antimicrobial protein P-2 expression in human skin at a single cell resolution using an amplified fluorescence in situ hybridization approach to detect P-2 mRNA in combination with immunophenotyping. We show that S. epidermidis activates GD T cells and upregulates P-2 in human skin ex vivo in a cell-specific manner. Furthermore, P-2 upregulation following S. epidermidis stimulation correlates with increased ability of skin cells to kill intracellular Staphylococcus aureus. Our findings are the first to reveal that skin commensal bacteria induce P-2 expression, which may be utilized beneficially to modulate host innate immune responses and protect from skin infections.

Cutaneous wound healing is a complex process involving numerous cell types to accomplish sequential, yet overlapping phases of inflammation, proliferation and tissue remodelling. 1,2 Immediately after injury, blood components are released into the wound, forming a clot which provides a matrix for the influx of inflammatory cells.The inflammatory phase is characterized by leukocyte migration to the wound. Neutrophils primarily remove bacteria, followed by monocytes which further differentiate into macrophages that exert early pro-inflammatory and late anti-inflammatory functions during the healing process. Deposition of the newly synthesized fibrin matrix and granulation tissue formation follow; these are subsequently replaced by collagen and scar tissue during the final stages of wound healing. The proliferative phase of wound healing is characterized by re-epithelialization, neovascularization and extracellular matrix deposition. 1,3 Historically, exploration of the molecular basis of wound healing has included a primary focus on its spatiotemporal regulation. Given the complexity of the wound healing process and its requirement for stringent regulation, epigenetic regulation including histone modifications and DNA methylation is highly likely to play a role. 4,5 Indeed, recent discoveries in the field of non-coding RNAs have identified roles for microRNAs (miRs), circular RNAs (circRNA) and long noncoding RNAs (lncRNA) as global gene expression regulators involved in an array of processes important for successful wound healing. [6][7][8][9] While the primary focus of previous reviews has been on the role of epigenetic modifications in acute wound healing, 4-8 herein we

The prevalence of infection in chronic wounds is well documented in the literature but not optimally studied due to the drawbacks of current methodologies. Here, we describe a tractable and simplified ex vivo human skin model of infection that addresses the critical drawbacks of high costs and limited translatability. Wounds were generated from excised abdominal skin from cosmetic procedures and cultured, inoculated with Staphylococcus aureus strain UAMS‐1, or under aseptic conditions. After three days, the infected wounds exhibited biofilm formation and significantly impaired reepithelialization compared to the control. Additionally, promigratory and proreparative genes were significantly downregulated, while proinflammatory genes were significantly upregulated, demonstrating molecular characterizations of impaired healing as in chronic wounds. This model allows for a simplified and versatile tool for the study of wound infection and subsequent development of novel therapies.

Fibrotic disease, which is implicated in almost half of all deaths worldwide, is the result of an uncontrolled wound healing response to injury in which tissue is replaced by deposition of excess extracellular matrix, leading to fibrosis and loss of organ function. A plethora of genome-wide association studies, microarrays, exome sequencing studies, DNA methylation arrays, next-generation sequencing, and profiling of noncoding RNAs have been performed in patient-derived fibrotic tissue, with the shared goal of utilizing genomics to identify the transcriptional networks and biological pathways underlying the development of fibrotic diseases. In this review, we discuss fibrosing disorders of the skin, liver, kidney, lung, and heart, systematically (1) characterizing the initial acute injury that drives unresolved inflammation, (2) identifying genomic studies that have defined the pathologic gene changes leading to excess matrix deposition and fibrogenesis, and (3) summarizing therapies targeting pro-fibrotic genes and networks identified in the genomic studies. Ultimately, successful bench-to-bedside translation of observations from genomic studies will result in the development of novel anti-fibrotic therapeutics that improve functional quality of life for patients and decrease mortality from fibrotic diseases.