Site-specific gene expression profiling as a novel strategy for unravelling keloid disease pathobiology

Abstract

Keloid disease (KD) is a fibroproliferative cutaneous tumour characterised by heterogeneity, excess collagen deposition and aggressive local invasion. Lack of a validated animal model and resistance to a multitude of current therapies has resulted in unsatisfactory clinical outcomes of KD management. In order to address KD from a new perspective, we applied for the first time a site-specific in situ microdissection and gene expression profiling approach, through combined laser capture microdissection and transcriptomic array. The aim here was to analyse the utility of this approach compared with established methods of investigation, including whole tissue biopsy and monolayer cell culture techniques. This study was designed to approach KD from a hypothesis-free and compartment-specific angle, using state-of-the-art microdissection and gene expression profiling technology. We sought to characterise expression differences between specific keloid lesional sites and elucidate potential contributions of significantly dysregulated genes to mechanisms underlying keloid pathobiology, thus informing future explorative research into KD. Here, we highlight the advantages of our in situ microdissection strategy in generating expression data with improved sensitivity and accuracy over traditional methods. This methodological approach supports an active role for the epidermis in the pathogenesis of KD through identification of genes and upstream regulators implicated in epithelial-mesenchymal transition, inflammation and immune modulation. We describe dermal expression patterns crucial to collagen deposition that are associated with TGFβ-mediated signalling, which have not previously been examined in KD. Additionally, this study supports the previously proposed presence of a cancer-like stem cell population in KD and explores the possible contribution of gene dysregulation to the resistance of KD to conventional therapy. Through this innovative in situ microdissection gene profiling approach, we provide better-defined gene signatures of distinct KD regions, thereby addressing KD heterogeneity, facilitating differential diagnosis with other cutaneous fibroses via transcriptional fingerprinting, and highlighting key areas for future KD research.

STAT3 signalling pathway is implicated in keloid pathogenesis by preliminary transcriptome and open chromatin analyses

“…Keloid formation is preceded by excessive inflammation, pruritis and pain. Scars expand beyond the confines of wounds and progress with a proliferative edge forming a raised scar and a collapsed centre . Fibroblasts are the principal mediator of fibroproliferative disorders .…”

“…Recent lineage tracing and single‐cell transcriptional profiling studies reveal that skin fibroblasts consist of distinct subpopulations arising from different lineages with different roles in determining dermal architecture in skin development and repair . A report combining site‐specific in situ microdissection and gene expression profiling of keloid tissues found distinct gene signatures of clear keloid regions highlighting morphological heterogeneity within the keloid scar . The study reveals novel keloid dermis gene signatures and supports the roles of dermal fibroblasts in the deposition of extracellular matrix (ECM) and in all phases of wound healing.…”

Targeting mTORC1/2 with OSI‐027 inhibits proliferation and migration of keloid keratinocytes

“…Keloid is characterized by the formation of exuberant and autonomous scar tissue that extends the clinical border of the original wound . It often forms as a result of dermal injuries, and is considered, to a limited extent, as a benign tumor .…”

“…Keloid is characterized by the formation of exuberant and autonomous scar tissue that extends the clinical border of the original wound . It often forms as a result of dermal injuries, and is considered, to a limited extent, as a benign tumor . A set of different chemokines, cytokines and growth factors are over‐secreted, which stimulate the proliferation and migration of keratinocytes (and other skin cells) to form keloid skin .…”

Multi‐dimensional models for functional testing of keloid scars: In silico, in vitro, organoid, organotypic, ex vivo organ culture, and in vivo models

“…The inflicted wounds are then allowed to heal in order to assess the wound healing phenotype of keloid scars. Although in vivo human biopsy models have proven vital in the identification of putative novel biomarkers of keloid, current single time point (likened to a mere snap shot of the disease process) patient biopsy models can neither explain the genetic predisposition to keloid scar formation nor the temporal relationship of its development.…”