Rivka C. Stone

Epithelial-mesenchymal transition in tissue repair and fibrosis

AbstractThe epithelial-mesenchymal transition (EMT) describes the global process by which stationary epithelial cells undergo phenotypic changes, including the loss of cell-cell adhesion and apical-basal polarity, and acquire mesenchymal characteristics that confer migratory capacity. EMT and its converse, MET (mesenchymal-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 plays a role in the development of scarring and fibrosis, as the matrix-producing myofibroblasts arise from cells of the epithelial lineage in response to injury but are 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 faulty repair of fibrotic wounds might identify components of EMT signaling as common therapeutic targets for impaired healing in many tissues. Graphical AbstractModel for injury-triggered EMT activation in physiologic wound repair (left) and fibrotic wound healing (right)

Integrative analysis of miRNA and mRNA paired expression profiling of primary fibroblast derived from diabetic foot ulcers reveals multiple impaired cellular functions.

Diabetic foot ulcers (DFUs) are one of the major complications of diabetes. Its molecular pathology remains poorly understood, impeding the development of effective treatments. Although it has been established that multiple cell types, including fibroblasts, keratinocytes, macrophages, and endothelial cells, all contribute to inhibition of healing, less is known regarding contributions of individual cell type. Thus, we generated primary fibroblasts from nonhealing DFUs and evaluated their cellular and molecular properties in comparison to nondiabetic foot fibroblasts (NFFs). Specifically, we analyzed both micro‐RNA and mRNA expression profiles of primary DFU fibroblasts. Paired genomic analyses identified a total of 331 reciprocal miRNA–mRNA pairs including 21 miRNAs (FC > 2.0) along with 239 predicted target genes (FC > 1.5) that are significantly and differentially expressed. Of these, we focused on three miRNAs (miR‐21‐5p, miR‐34a‐5p, miR‐145‐5p) that were induced in DFU fibroblasts as most differentially regulated. The involvement of these microRNAs in wound healing was investigated by testing the expression of their downstream targets as well as by quantifying cellular behaviors in prospectively collected and generated cell lines from 15 patients (seven DFUF and eight NFF samples). We found large number of downstream targets of miR‐21‐5p, miR‐34a‐5p, miR‐145‐5p to be coordinately regulated in mRNA profiles, which was confirmed by quantitative real‐time PCR. Pathway analysis on paired miRNA–mRNA profiles predicted inhibition of cell movement and cell proliferation, as well as activation of cell differentiation and senescence in DFU fibroblasts, which was confirmed by cellular assays. We concluded that induction of miR‐21‐5p, miR‐34a‐5p, miR‐145‐5p in DFU dermal fibroblasts plays an important role in impairing multiple cellular functions, thus contributing to overall inhibition of healing in DFUs.

A bioengineered living cell construct activates an acute wound healing response in venous leg ulcers

A bioengineered bilayered living cellular construct promotes ulcer healing by modulating inflammation, stimulating wound edge keratinocytes, and attenuating Wnt/β-catenin signaling to activate an acute wound response. Activating healing in chronic wounds Effective therapies for chronic venous leg ulcers (VLUs) remain elusive, in part, because of the incomplete understanding of the pathophysiology of nonhealing wounds. Stone et al. conducted a postmarket clinical trial using transcriptomics to understand the mechanisms of action of an FDA-approved bilayered living cellular construct (BLCC) in nonhealing VLUs. After 1 week of BLCC treatment in addition to standard of care compression therapy, nonhealing VLUs showed changes in inflammation and gene expression characteristic of acutely healing wounds. This study provides mechanistic insight into how the acute healing process can be activated by a cell therapy in chronic nonhealing wounds. Chronic nonhealing venous leg ulcers (VLUs) are widespread and debilitating, with high morbidity and associated costs; about

Skin Metabolite, Farnesyl Pyrophosphate, Regulates Epidermal Response to Inflammation, Oxidative Stress, and Migration.

15 billion is spent annually on the care of VLUs in the United States. Despite this, there is a paucity of treatments for VLUs because of the lack of pathophysiologic insight into ulcer development as well as the lack of knowledge regarding biologic actions of existing VLU-targeted therapies. The bioengineered bilayered living cellular construct (BLCC) skin substitute is a U.S. Food and Drug Administration–approved biologic treatment for healing VLUs. To elucidate the mechanisms through which the BLCC promotes healing of chronic VLUs, we conducted a clinical trial (NCT01327937) in which patients with nonhealing VLUs were treated with either standard of care (compression therapy) or the BLCC together with standard of care. Tissue was collected from the VLU edge before and 1 week after treatment, and the samples underwent comprehensive microarray mRNA and protein analyses. Ulcers treated with the BLCC skin substitute displayed three distinct transcriptomic patterns, suggesting that BLCC induced a shift from a nonhealing to a healing tissue response, involving modulation of inflammatory and growth factor signaling, keratinocyte activation, and attenuation of Wnt/β-catenin signaling. In these ways, BLCC application orchestrated a shift from the chronic nonhealing ulcer microenvironment to a distinctive healing milieu resembling that of an acute, healing wound. Our findings provide in vivo evidence in VLU patients of pathways that can be targeted in the design of new therapies to promote healing of chronic VLUs.

Giant Basal Cell Carcinomas Arising on the Bilateral Forearms of a Patient: A Case Report and Review of Nonsurgical Treatment Options

Skin produces cholesterol and a wide array of sterols and non‐sterol mevalonate metabolites, including isoprenoid derivative farnesyl pyrophosphate (FPP). To characterize FPP action in epidermis, we generated transcriptional profiles of primary human keratinocytes treated with zaragozic acid (ZGA), a squalene synthase inhibitor that blocks conversion of FPP to squalene resulting in endogenous accumulation of FPP. The elevated levels of intracellular FPP resulted in regulation of epidermal differentiation and adherens junction signaling, insulin growth factor (IGF) signaling, oxidative stress response and interferon (IFN) signaling. Immunosuppressive properties of FPP were evidenced by STAT‐1 downregulation and prominent suppression of its nuclear translocation by IFNγ. Furthermore, FPP profoundly downregulated genes involved in epidermal differentiation of keratinocytes in vitro and in human skin ex vivo. Elevated levels of FPP resulted in induction of cytoprotective transcriptional factor Nrf2 and its target genes. We have previously shown that FPP functions as ligand for the glucocorticoid receptor (GR), one of the major regulator of epidermal homeostasis. Comparative microarray analyses show significant but not complete overlap between FPP and glucocorticoid regulated genes, suggesting that FPP may have wider transcriptional impact. This was further supported by co‐transfection and chromatin immunoprecipitation experiments where we show that upon binding to GR, FPP recruits β‐catenin and, unlike glucocorticoids, recruits co‐repressor GRIP1 to suppress keratin 6 gene. These findings have many clinical implications related to epidermal lipid metabolism, response to glucocorticoid therapy as well as pleiotropic effects of cholesterol lowering therapeutics, statins. J. Cell. Physiol. 231: 2452–2463, 2016.

Novel mevalonate kinase missense mutation in a patient with disseminated superficial actinic porokeratosis

Giant basal cell carcinomas (GBCCs) are large basal cell carcinomas (BCCs; <5 cm) with a greater propensity to invade and metastasize than standard BCCs. The presence of 2 GBCCs in a single individual is rare. We present the case of a 71-year-old Caucasian male with bilateral GBCCs on the dorsal forearms, measuring 130 cm2 and 24 cm2, respectively, that developed over a 21-year period. Over this period, the patient treated the tumors with herbal remedies. Histologic evaluation showed a conventional nodular BCC for both tumors. Computed tomography and magnetic resonance imaging revealed a T4N0M0 stage for the larger lesion. Surgical excision and grafting and reconstruction were offered, but he declined. This case highlights a shared belief in holistic treatments and rejection of Western medical interventions that are common among many patients with GBCC. Studies reporting nonsurgical treatments for GBCCs, including radiotherapy, vismodegib, topical imiquimod, and acitretin are reviewed.

Staphylococcus aureus Triggers Induction of miR-15B-5P to Diminish DNA Repair and Deregulate Inflammatory Response in Diabetic Foot Ulcers

DSAP: disseminated superficial actinic porokeratosis MVK: mevalonate kinase NCBI: National Center for Biotechnology Information INTRODUCTION Disseminated superficial actinic porokeratosis (DSAP) is a genodermatosis with autosomal dominant inheritance and near-complete penetrance clinically featuring uniform 3to 7-mm annular lesions with scaly borders on sun-exposed face and extremities. The hyperkeratotic rim correlates histopathologically with the presence of a cornoid lamella. Dermoscopy may be used to noninvasively visualize the cornoid lamella, which appears as a distinctive thin white annular structure at the periphery of each lesion. Several causal DSAP mutations have previously been reported in members of the mevalonate/isoprenoid biosynthesis pathway, although the exact mechanism is not well understood. We report a patient who presented with classic clinical and histopathologic features of DSAP in which a novel mutation in a coding region of the mevalonate kinase (MVK) gene was identified via Sanger sequencing of the skin biopsy specimen.