A novel regulatory function for miR-29a in keloid fibrogenesis

LINC00525 promotes cell proliferation and collagen expression through feedforward regulation of TGF-β signaling in hypertrophic scar fibroblasts

The etiology of hypertrophic scar formation continues to elude researchers, despite advancements in the understanding of skin scarring. Several long non-coding RNAs (lncRNAs) have been implicated in the pathogenesis of hypertrophic scars, yet the role and molecular mechanisms of LINC00525 in this process remain unclear. This study demonstrates that LINC00525 enhances cell proliferation and collagen expression through knockdown and overexpression techniques. Further analysis, including nuclear and cytoplasmic localization studies, RNA pull-down assays, bioinformatics predictions, and PCR validation, reveals that LINC00525 interacts with miR-29a-5p. The downregulation of LINC00525 enhances the expression of miR-29a-5p and suppresses the TGF-β/Smad signaling pathway. Additionally, TGF-β1 induces the upregulation of LINC00525. Collectively, these findings indicate that LINC00525 operates through a feedforward mechanism to regulate TGF-β signaling in hypertrophic scar fibroblasts. This research offers novel insights for the prevention and treatment of scars.

Release of miR-29 Target Laminin C2 Improves Skin Repair

miRNAs are small noncoding RNAs that regulate mRNA targets in a cell-specific manner. miR-29 is expressed in murine and human skin, where it may regulate functions in skin repair. Cutaneous wound healing model in miR-29a/b1 gene knockout mice was used to identify miR-29 targets in the wound matrix, where angiogenesis and maturation of provisional granulation tissue was enhanced in response to genetic deletion of miR-29. Consistently, antisense-mediated inhibition of miR-29 promoted angiogenesis in vitro by autocrine and paracrine mechanisms. These processes are likely mediated by miR-29 target mRNAs released upon removal of miR-29 to improve cell-matrix adhesion. One of these, laminin (Lam)-c2 (also known as laminin γ2), was strongly up-regulated during skin repair in the wound matrix of knockout mice. Unexpectedly, Lamc2 was deposited in the basal membrane of endothelial cells in blood vessels forming in the granulation tissue of knockout mice. New blood vessels showed punctate interactions between Lamc2 and integrin α6 (Itga6) along the length of the proto-vessels, suggesting that greater levels of Lamc2 may contribute to the adhesion of endothelial cells, thus assisting angiogenesis within the wound. These findings may be of translational relevance, as LAMC2 was deposited at the leading edge in human wounds, where it formed a basal membrane for endothelial cells and assisted neovascularization. These results suggest a link between LAMC2, improved angiogenesis, and re-epithelialization.

Characterization of the skin keloid microenvironment

Keloids are a fibroproliferative skin disorder that develops in people of all ages. Keloids exhibit some cancer-like behaviors, with similar genetic and epigenetic modifications in the keloid microenvironment. The keloid microenvironment is composed of keratinocytes, fibroblasts, myofibroblasts, vascular endothelial cells, immune cells, stem cells and collagen fibers. Recent advances in the study of keloids have led to novel insights into cellular communication among components of the keloid microenvironment as well as potential therapeutic targets for treating keloids. In this review, we summarized the nature of genetic and epigenetic regulation in keloid-derived fibroblasts, epithelial-to-mesenchymal transition of keratinocytes, immune cell infiltration into keloids, the differentiation of keloid-derived stem cells, endothelial-to-mesenchymal transition of vascular endothelial cells, extracellular matrix synthesis and remodeling, and uncontrolled angiogenesis in keloids with the aim of identifying new targets for therapeutic benefit. Video Abstract.

MicroRNA-29a Mitigates Laminectomy-Induced Spinal Epidural Fibrosis and Gait Dysregulation by Repressing TGF-β1 and IL-6

Spinal epidural fibrosis is one of the typical features attributable to failed back surgery syndrome, with excessive scar development in the dura and nerve roots. The microRNA-29 family (miR-29s) has been found to act as a fibrogenesis-inhibitory factor that reduces fibrotic matrix overproduction in various tissues. However, the mechanistic basis of miRNA-29a underlying the overabundant fibrotic matrix synthesis in spinal epidural scars post-laminectomy remained elusive. This study revealed that miR-29a attenuated lumbar laminectomy-induced fibrogenic activity, and epidural fibrotic matrix formation was significantly lessened in the transgenic mice (miR-29aTg) as compared with wild-type mice (WT). Moreover, miR-29aTg limits laminectomy-induced damage and has also been demonstrated to detect walking patterns, footprint distribution, and moving activity. Immunohistochemistry staining of epidural tissue showed that miR-29aTg was a remarkably weak signal of IL-6, TGF-β1, and DNA methyltransferase marker, Dnmt3b, compared to the wild-type mice. Taken together, these results have further strengthened the evidence that miR-29a epigenetic regulation reduces fibrotic matrix formation and spinal epidural fibrotic activity in surgery scars to preserve the integrity of the spinal cord core. This study elucidates and highlights the molecular mechanisms that reduce the incidence of spinal epidural fibrosis, eliminating the risk of gait abnormalities and pain associated with laminectomy.

Mechanisms underlying pathological scarring by fibroblasts during wound healing

Pathological scarring is an abnormal outcome of wound healing, which often manifests as excessive proliferation and transdifferentiation of fibroblasts (FBs), and excessive deposition of the extracellular matrix. FBs are the most important effector cells involved in wound healing and scar formation. The factors that promote pathological scar formation often act on the proliferation and function of FB. In this study, we describe the factors that lead to abnormal FB formation in pathological scarring in terms of the microenvironment, signalling pathways, epigenetics, and autophagy. These findings suggest that understanding the causes of abnormal FB formation may aid in the development of precise and effective preventive and treatment strategies for pathological scarring that are associated with improved quality of life of patients.

The Role of miR-29 Family in TGF-β Driven Fibrosis in Glaucomatous Optic Neuropathy

Primary open angle glaucoma (POAG), a chronic optic neuropathy, remains the leading cause of irreversible blindness worldwide. It is driven in part by the pro-fibrotic cytokine transforming growth factor beta (TGF-β) and leads to extracellular matrix remodelling at the lamina cribrosa of the optic nerve head. Despite an array of medical and surgical treatments targeting the only known modifiable risk factor, raised intraocular pressure, many patients still progress and develop significant visual field loss and eventual blindness. The search for alternative treatment strategies targeting the underlying fibrotic transformation in the optic nerve head and trabecular meshwork in glaucoma is ongoing. MicroRNAs are small non-coding RNAs known to regulate post-transcriptional gene expression. Extensive research has been undertaken to uncover the complex role of miRNAs in gene expression and miRNA dysregulation in fibrotic disease. MiR-29 is a family of miRNAs which are strongly anti-fibrotic in their effects on the TGF-β signalling pathway and the regulation of extracellular matrix production and deposition. In this review, we discuss the anti-fibrotic effects of miR-29 and the role of miR-29 in ocular pathology and in the development of glaucomatous optic neuropathy. A better understanding of the role of miR-29 in POAG may aid in developing diagnostic and therapeutic strategies in glaucoma.

Identifying miRNAs Associated with the Progression of Keloid through mRNA-miRNA Network Analysis and Validating the Targets of miR-29a-3p in Keloid Fibroblasts

Background. Keloid has brought great trouble to people and currently has no uniformly successful treatment. It is urgent to find new targets to effectively prevent the progress of keloid. The current research mainly identifies the differentially expressed genes (DEGs) in keloid through high-throughput sequencing technology and bioinformatics analysis technology, to screen new therapeutic targets and potential biomarkers. However, due to the different samples, different control groups, and small sample sizes, the sequencing results obtained from different studies are quite different and lack reliability. It is necessary to analyze the existing datasets in a reasonable way. Methods. Datasets about keloid were filtered in Gene Expression Omnibus (GEO) and ArrayExpress databases according to the inclusion and exclusion criteria. The discovery datasets were used for summarizing significant DEGs, and the validation datasets were to validate the mRNA and miRNA expression levels. The Encyclopedia of RNA Interactomes (ENCORI) online platform was used to predict the interactions between miRNAs and their target mRNAs. Protein-protein interaction network (PPI network) analysis and functional enrichment analysis were conducted. miRNA-mRNA network was established by Cytoscape software and verified in keloid tissue ( $n=8$ ) by RT-qPCR. miR-29a-3p mimic and inhibitor were transfected into keloid fibroblasts (KFs) to preliminary verify its targets, the prognostic value of which was estimated by the receiver operating characteristic (ROC) curve. Results. A total of 6 datasets involving 20 patients were included. 15 miRNAs and 12 target mRNAs were identified as potential biomarkers for keloid patients. The RT-qPCR results showed that miR-29a-3p, miR-92a-3p, and miR-143-3p were downregulated, and all their target mRNAs were upregulated in keloid tissue ( $P<0.05$ ). The expression of COL1A1, COL1A2, COL3A1, COL5A1, and COL5A2 decreased when miR-29a-3p was overexpressed but increased when miR-29a-3p was knocked down ( $P<0.05$ ). And these genes had a good performance in the diagnosis of keloid, especially when using keloid nonlesional skin or normal scar tissues as controls. Conclusion. The miRNA-mRNA network, especially miR-29a-3p and its targets, may provide insights into the underlying pathogenesis of keloid and serve as potential biomarkers for keloid treatment.

A time to heal: microRNA and circadian dynamics in cutaneous wound repair

Many biological systems have evolved circadian rhythms based on the daily cycles of daylight and darkness on Earth. Such rhythms are synchronised or entrained to 24-h cycles, predominantly by light, and disruption of the normal circadian rhythms has been linked to elevation of multiple health risks. The skin serves as a protective barrier to prevent microbial infection and maintain homoeostasis of the underlying tissue and the whole organism. However, in chronic non-healing wounds such as diabetic foot ulcers (DFUs), pressure sores, venous and arterial ulcers, a variety of factors conspire to prevent wound repair. On the other hand, keloids and hypertrophic scars arise from overactive repair mechanisms that fail to cease in a timely fashion, leading to excessive production of extracellular matrix (ECM) components such as such as collagen. Recent years have seen huge increases in our understanding of the functions of microRNAs (miRNAs) in wound repair. Concomitantly, there has been growing recognition of miRNA roles in circadian processes, either as regulators or targets of clock activity or direct responders to external circadian stimuli. In addition, miRNAs are now known to function as intercellular signalling mediators through extracellular vesicles (EVs). In this review, we explore the intersection of mechanisms by which circadian and miRNA responses interact with each other in relation to wound repair in the skin, using keratinocytes, macrophages and fibroblasts as exemplars. We highlight areas for further investigation to support the development of translational insights to support circadian medicine in the context of these cells.

Aberrantly Expressed Small Noncoding RNAome in Keloid Skin Tissue

The skin is an organ that protects against injury and infection but can be damaged easily. Wound healing is a subtle balance which, if broken, can lead to keloid formation. Small noncoding (nc) RNAs can be of “housekeeping,” for example, ribosomal RNAs and transfer RNAs, or “regulatory,” for example, microRNAs (miRNAs or miRs), small nucleolar RNAs (snoRNAs), and P-element–induced Wimpy testis (PIWI)-interacting RNA (piRNA) types. We examined five types of small ncRNAs [miR, piRNA, snoRNA, small nuclear (sn) RNA, and repeat-associated small interfering RNA (rasiRNA)] in keloid skin tissue (KST) using sequencing and real-time reverse transcription-quantitative polymerase chain reaction. All comparisons were made in relation to expression in normal skin tissue (obtained by abdominoplasty). The expression of three piRNAs was upregulated, and the expression of six piRNAs was downregulated in KST. The expression of 12 snoRNAs was upregulated, and the expression of two snoRNAs was downregulated in KST. The expression of two snRNAs was downregulated in KST. The expression of 18 miRs was upregulated, and the expression of three miRNAs was downregulated in KST. The expression of one rasiRNA was upregulated, and the expression of one rasiRNA was downregulated in KST. We revealed the differential expression of small ncRNAs in KST, which may aid the development of new treatment for keloids.

Beyond the Code: Noncoding RNAs in Skin Wound Healing

An increasing number of noncoding RNAs (ncRNAs) have been found to regulate gene expression and protein functions, playing important roles in diverse biological processes and diseases. Their crucial functions have been reported in almost every cell type and all stages of skin wound healing. Evidence of their pathogenetic roles in common wound complications, such as chronic nonhealing wounds and excessive scarring, is also accumulating. Given their unique expression and functional properties, ncRNAs are promising therapeutic and diagnostic entities. In this review, we discuss current knowledge about the functional roles of noncoding elements, such as microRNAs, long ncRNAs, and circular RNAs, in skin wound healing, focusing on in vivo evidence from studies of human wound samples and animal wound models. Finally, we provide a perspective on the outlook of ncRNA-based therapeutics in wound care.

MicroRNA-29a May Influence Myopia Development by Regulating Collagen I

PURPOSE

The aim of this study was to characterize the regulatory role of microRNA-29a (miR-29a) in myopia, providing support for potential biomarkers and new therapeutic targets of myopia in humans.

METHODS

The miR-29a expression level was detected in the aqueous humor and peripheral blood plasma of 21 high myopic patients and eight cataract control patients using quantitative polymerase chain reaction. iTRAQ analysis of proteomes was conducted to show the regulatory effect of miR-29a on human scleral fibroblasts (SFs) cultured in vitro. We also assessed proliferation, migration, and collagen I synthesis in SF cells, mediated by miR-29a.

RESULTS

MiR-29a expression was significantly higher in the aqueous humor of highly myopic patients than in the cataract control patients (fold change: 4.861, p = 0.001). miR-29a inhibited the synthesis of type I collagen in human SF cells and enhanced cell migration, but had no significant effect on cell proliferation.

CONCLUSION

MiR-29a was highly expressed in aqueous humor of myopia patients and inhibited the synthesis of type I collagen in human SF cells in vivo, thereby it may play an important role in myopia development.

The epigenetics of keloids

Keloid scarring is a fibroproliferative disorder of the skin with unknown pathophysiology, characterised by fibrotic tissue that extends beyond the boundaries of the original wound. Therapeutic options are few and commonly ineffective, with keloids very commonly recurring even after surgery and adjunct treatments. Epigenetics, defined as alterations to the DNA not involving the base-pair sequence, is a key regulator of cell functions, and aberrant epigenetic modifications have been found to contribute to many pathologies. Multiple studies have examined many different epigenetic modifications in keloids, including DNA methylation, histone modification, microRNAs and long non-coding RNAs. These studies have established that epigenetic dysregulation exists in keloid scars, and successful future treatment of keloids may involve reverting these aberrant modifications back to those found in normal skin. Here we summarise the clinical and experimental studies available on the epigenetics of keloids, discuss the major open questions and future perspectives on the treatment of this disease.

Cell-Free Biological Approach for Corneal Stromal Wound Healing

Corneal opacification is the fourth most common cause of blindness globally behind cataracts, glaucoma, and age-related macular degeneration. The standard treatment of serious corneal scarring is corneal transplantation. Though it is effective for restoring vision, the treatment outcome is not optimal, due to limitations such as long-term graft survival, lifelong use of immunosuppressants, and a loss of corneal strength. Regulation of corneal stromal wound healing, along with inhibition or downregulation of corneal scarring is a promising approach to prevent corneal opacification. Pharmacological approaches have been suggested, however these are fraught with side effects. Tissue healing is an intricate process that involves cell death, proliferation, differentiation, and remodeling of the extracellular matrix. Current research on stromal wound healing is focused on corneal characteristics such as the immune response, angiogenesis, and cell signaling. Indeed, promising new technologies with the potential to modulate wound healing are under development. In this review, we provide an overview of cell-free strategies and some approaches under development that have the potential to control stromal fibrosis and scarring, especially in the context of early intervention.

Bioinformatic Analysis of Key Genes and Pathways Related to Keloids

Background

The pathophysiology of keloids is complex, and the treatment for keloids is still an unmet medical need. Our study is aimed at identifying the hub genes among the differentially expressed genes (DEGs) between normal skin tissue and keloids and key pathways in the development of keloids.

Materials and Methods

We downloaded the GSE92566 and GSE90051 microarray data, which contain normal skin tissue and keloid gene expression data. GSE92566 was treated as a discovery dataset for summarizing the significantly DEGs, and GSE90051 served as a validation dataset. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes pathway, Reactome enrichment analysis, gene set enrichment analysis, and gene set variation analysis were performed for the key functions and pathways enriched in DEGs. Moreover, we also validated the hub genes identified from the protein-protein interaction network and predicted miRNA-hub gene interactions.

Results

117 downregulated DEGs and 204 upregulated DEGs in GSE92566 were identified. Extracellular and collagen-related pathways were prominent in upregulated DEGs, while the keratinization-related pathway was associated with downregulated DEGs. The hub genes included COL5A1, COL5A2, and SERPINH1, which were also validated in GSE90051.

Conclusion

This study identified several hub genes and provided insights for the underlying pathways and miRNA-hub gene interactions for keloid development through bioinformatic analysis of two microarray datasets. Additionally, our results would support the development of future therapeutic strategies.

Epigenetic modification mechanisms involved in keloid: current status and prospect

Keloid, a common dermal fibroproliferative disorder, is benign skin tumors characterized by the aggressive fibroblasts proliferation and excessive accumulation of extracellular matrix. However, common therapeutic approaches of keloid have limited effectiveness, emphasizing the momentousness of developing innovative mechanisms and therapeutic strategies. Epigenetics, representing the potential link of complex interactions between genetics and external risk factors, is currently under intense scrutiny. Accumulating evidence has demonstrated that multiple diverse and reversible epigenetic modifications, represented by DNA methylation, histone modification, and non-coding RNAs (ncRNAs), play a critical role in gene regulation and downstream fibroblastic function in keloid. Importantly, abnormal epigenetic modification manipulates multiple behaviors of keloid-derived fibroblasts, which served as the main cellular components in keloid skin tissue, including proliferation, migration, apoptosis, and differentiation. Here, we have reviewed and summarized the present available clinical and experimental studies to deeply investigate the expression profiles and clarify the mechanisms of epigenetic modification in the progression of keloid, mainly including DNA methylation, histone modification, and ncRNAs (miRNA, lncRNA, and circRNA). Besides, we also provide the challenges and future perspectives associated with epigenetics modification in keloid. Deciphering the complicated epigenetic modification in keloid is hopeful to bring novel insights into the pathogenesis etiology and diagnostic/therapeutic targets in keloid, laying a foundation for optimal keloid ending.

Circulating miRNA-181b-5p, miRNA-223-3p, miRNA-210-3p, let 7i-5p, miRNA-21-5p and miRNA-29a-3p in patients with localized scleroderma as potential biomarkers

Localized scleroderma (LoSc) is a rare disease manifested by an inflammation and sclerosis of the skin. The latest studies focused on glycoprotein Krebs von den Lungen-6, surfactant protein-D, chemokine ligand 18 and dipeptidylpeptidase 4 as potential biomarkers of skin fibrosis in systemic scleroderma. Our study aimed to identify 6 miRNAs with elevated or decreased levels in 38 LoSc patients (31 females, 7 males) compared to healthy volunteers (HVs) and to correlate the selected miRNAs' serum levels with the severity and the clinical symptoms of LoSc and some laboratory parameters with the selected miRNAs' serum levels. The serum levels of miRNAs, i.e. miRNA-181b-5p, miRNA-223-3p, miRNA-21-5p, let 7i-5p, miRNA-29a-3p and miRNA-210-3p were significantly increased in the LoSc patients compared to the HVs. The level of let-7i increase in the female LoSc patients correlated negatively with BSA (r =  - 0.355, p = 0.049) and mLoSSI (r =  - 0.432, p = 0.015). Moreover, the female patients with inactive LoSc had significantly higher level of let-7i (2.68-fold on average) in comparison to those with active disease (p = 0.045). The exact role of those molecules has not been revealed in LoSc and a long-term longitudinal research is pivotal to confirm their prognostic value.

BTXA regulates the epithelial-mesenchymal transition and autophagy of keloid fibroblasts via modulating miR-1587/miR-2392 targeted ZEB2

Keloids are very resistant to treatment in dermatology and plastic surgical practice. The present study aimed to explore the underlying mechanism of botulinum toxin A (BTXA) treated human skin keloid fibroblasts (HSFBs) proving some new insights into keloids treatment. Expression of miR-1587 and miR-2392 were significantly down-regulated in keloid tissues and HSFBs, while the ZEB2 was a target of both and up-regulated in keloid tissues and HSFBs compared with the normal controls. BTXA could significantly increase the expression of miR-1587 and miR-2392 but decrease the expression of ZEB2. BTXA could significantly inhibit the proliferation, cell cycle, and migration and promote apoptosis and autophagy of HSFBs; however, miR-1587 and miR-2392 inhibitors could reverse these effects of BTXA on HSFBs. Silencing ZEB2 could significantly attenuate the effects of miR-1587 and miR-2392 inhibitors in promoting cell proliferation and migration and suppressing apoptosis and autophagy of HSFBs after treating with BTXA. BTXA could suppress the proliferation and migration and promote apoptosis and autophagy of HSFBs via modulating miR-1587/miR-2392 targeted ZEB2.

Keloids: a review of therapeutic management

Keloid scar formation arises from a disorganized fibroproliferative collagen response that extends beyond the original wound margins because of excessive production of extracellular matrix (ECM). Despite treatment options for keloid scars including medical and surgical therapies, such as intralesional steroid injection and surgical excision, the recurrence rate remains high. Herein we consolidate recently published narrative reviews, systematic reviews, and meta-analyses to provide an overview of updated treatment recommendations for keloidal scar formation. PubMed search engine was used to access the MEDLINE database to investigate updates regarding keloid incidence and treatment. More than 100 articles were reviewed. Keloid management remains a multimodal approach. There continues to be no gold standard of treatment that provides a consistently low recurrence rate; however, the increasing number of available treatments and synergistic combinations of these treatments (i.e., laser-based devices in combination with intralesional steroids, or 5-fluorouracil (5-FU) in combination with steroid therapy) is showing favorable results. Future studies could target the efficacy of novel treatment modalities (i.e., autologous fat grafting or stem cell-based therapies) for keloid management. This review article provides updated treatment guidelines for keloids and discusses insight into management to assist patient-focused, evidence-based clinical decision making.

Effects of the circ_101238/miR-138-5p/CDK6 axis on proliferation and apoptosis keloid fibroblasts

The formation of keloid scars is normally induced by cutaneous injuries, however, the detailed mechanisms underlying keloid formation remain largely unknown. The present study aimed to investigate the effects of circular RNA_101238 (circ_101238) on the proliferation and apoptosis of keloid fibroblasts and to identify the underlying molecular mechanisms of these effects. Reverse transcription-quantitative (RT-q)PCR was performed to determine the expression levels of circ_101238, microRNA (miRNA/miR)-138-5p and cyclin-dependent kinase 6 (CDK6) in keloids and normal skin tissues. Following transfection with short hairpin (sh)-circ_101238, LV-circ_101238, miR-138-5p mimics, miR-138-5p inhibitors and small interfering (si)-CDK6, cell proliferation was assessed using a cell counting kit-8 assay. Furthermore, cell apoptosis was evaluated via flow cytometric analysis, while a dual-luciferase assay was performed to confirm interactions between circ_101238, miR-138-5p and CDK6. The expression levels of the proliferation marker, CDK6 and apoptosis marker, caspase-3 were determined via RT-qPCR and western blot analyses. The results demonstrated that expression levels of circ_101238 and CDK6 were significantly increased in keloid samples, while miR-138-5p expression was reduced in comparison to normal skin. Furthermore, circ_101238 was demonstrated to bind miR-138-5p, which subsequently targeted CDK6. Proliferative activity and CDK6 expression were significantly decreased in keloid fibroblasts following transfection with sh-circ_101238 or miR-138-5p mimics, while cell apoptosis was markedly increased. Furthermore, co-transfection with miR-138-5p mimics reversed the effects caused by overexpression of circ_101238. Treatment of keloid fibroblasts with si-CDK6 counteracted the biological behavior changes induced by miR-138-5p inhibitors. Additionally, transfection with LV-CDK6 reversed the effects caused by miR-138-5p mimics. Taken together, the results of the present study demonstrated that circ_101238 was upregulated in keloid tissues in comparison with normal tissues and that circ_101238 knockdown inhibited cell proliferation, while promoting apoptosis of keloid fibroblasts via the miR-138-5p/CDK6 axis. These results suggest that circ_101238 may serve as a promising therapeutic candidate for keloid therapy and that circ_101238/miR-138-5p/CDK6 signaling has the potential to regulate the growth of keloid fibroblasts.

TM4SF1 involves in miR-1-3p/miR-214-5p-mediated inhibition of the migration and proliferation in keloid by regulating AKT/ERK signaling

AIMS

Transmembrane 4 L six family member 1 (TM4SF1) is a small plasma membrane glycoprotein that is highly expressed in cancers. However, the role of TM4SF1 that plays in keloids remains unknown. We investigated the expression, function and the microRNA (miRNA) regulatory network of TM4SF1 in keloids.

MAIN METHODS

Small interfering RNAs and lentivirus were used to alter the expression of TM4SF1 in fibroblasts. Dual-luciferase reporter assays were applied to determine the miRNA targets. Immunohistochemistry, western blotting, qRT-PCR, wound healing assays, Transwell assays, cell count kit-8 assays and flow cytometry were also employed in this study.

KEY FINDINGS

TM4SF1 was frequently upregulated in human keloid fibroblasts (HKFs) compared with human normal skin fibroblasts (HSFs). The downregulation of TM4SF1 significantly inhibited proliferation and migration, and induced apoptosis in HKFs. Furthermore, si-TM4SF1 inhibited the AKT/ERK signaling. Meanwhile, the upregulation of TM4SF1 promoted proliferation, migration and the activation of AKT/ERK signaling in human foreskin fibroblasts (HFF-1). Moreover, TM4SF1 can be regulated by miRNAs, which have been validated to play important roles in keloids by posttranscriptional regulation of gene expression. After screening, we found miR-1-3p and miR-214-5p targeted TM4SF1, inhibited TM4SF1 expression, cell proliferation, migration, and induced apoptosis in HKFs. And the level of miR-1-3p and miR-214-5p were found lower in HKFs than in HSFs.

SIGNIFICANCE

Our study demonstrates a novel regulatory mechanism by which miR-1-3p, miR-214-5p, and TM4SF1 are involved in proliferation, cell motility, and apoptosis, suggesting that they may be potential targets in therapies for keloids.

lncRNA-H19/miR-29a axis affected the viability and apoptosis of keloid fibroblasts through acting upon COL1A1 signaling

This study was intended to clarify the potential of applying the long-chain noncoding RNA H19/miR-29a axis in keloid treatment by elucidating its correlation with the activity of fibroblasts. In this study, 80 keloid tissues, 63 normal fibrous tissues, and 91 normal skin tissues were collected in advance, and concurrently, fibroblasts separated from the tissues were cultured. Besides this, the si-H19, pcDNA3.1-H19, miR-29a mimic, and miR-29a inhibitor were transfected to keloid fibroblasts, whose proliferation, apoptosis, and metastasis were appraised by employing the colony formation assay, flow cytometry, and transwell assay. In addition, the luciferase reporter gene assay was carried out to determine whether targeted regulation was present between H19 and miR-29a, as well as between miR-29a and COL1A1. The study results demonstrated that keloid tissues and fibroblasts exhibited observably upregulated H19 expression and downregulated miR-29a expression, relative to normal skin tissues and fibroblasts (P < .05). Also observed was a negative correlation between H19 expression and miR-29a expression among the gathered keloid tissues (r_s  = -.267, P = .017). Furthermore, in vitro transfection of pcDNA3.1-H19 or miR-29a inhibitor could intensify viability, proliferation, migration, and invasion of the fibroblasts (P < .05), while silencing of H19 and overexpression of miR-29a hindered both metastasis and multiplication of the fibroblasts significantly (P < .05). In addition, H19 was capable of altering miR-29a expression within fibroblasts by directly sponging it, and overexpression of COL1A1 could deter the impact of miR-29a on viability, proliferation, migration, and invasion of fibroblasts (P < .05). In conclusion, H19 might facilitate proliferation and metastasis of fibroblasts by modifying downstream miR-29a and COL1A1, which was expected to allow for development of keloid-targeted treatments.

Calcimycin Suppresses S100A4 Expression and Inhibits the Stimulatory Effect of Transforming Growth Factor β1 on Keloid Fibroblasts

Recent researches have indicated that S100A4 participates in tissue fibrosis, whereas calcimycin inhibits this process as a novel S100A4 transcription inhibitor. However, the relationship and mechanisms between calcimycin and S100A4 in keloid fibroblasts (KFs) remain unknown. The present research was aimed to evaluate the effect of calcimycin on S100A4 expression and pathogenesis in KFs. Keloid fibroblasts were cultured and exposed to different concentrations of calcimycin in the absence or presence of transforming growth factor β1 (TGF-β1). The results showed that the expression of S100A4 was significantly increased in keloid derived fibroblasts compared with normal skin fibroblasts. Calcimycin depressed S100A4 in a concentration- and time-dependent manner. Moreover, calcimycin suppressed TGF-β1-induced collagen type I, fibronectin, and α-smooth muscle actin expression and cell viability in cultured KFs. Furthermore, calcimycin modulated expression of TGF-β/Smad target genes Smad7 and phosphorylation of TGF-β1-induced Smad2/3. This research for the first time confirmed the presence of S100A4 in KFs. Calcimycin inhibits the expression of S100A4, as well as KF proliferation and migration and extracellular matrix (ECM) synthesis. Taken together, these results indicate that calcimycin might be a therapeutic candidate to keloid or other related fibrotic disorders.

Augmenting canonical Wnt signalling in therapeutically inert cells converts them into therapeutically potent exosome factories

Cardiosphere-derived cells (CDCs) are therapeutic candidates with disease-modifying bioactivity, but their variable potency has complicated their clinical translation. Transcriptomic analyses of CDCs from human donors have revealed that the therapeutic potency of these cells correlates with Wnt/β-catenin signalling and with β-catenin protein levels. Here, we show that skin fibroblasts engineered to overexpress β-catenin and the transcription factor Gata4 become immortal and therapeutically potent. Transplantation of the engineered fibroblasts into a mouse model of acute myocardial infarction led to improved cardiac function and mouse survival. And in the mdx mouse model of Duchenne muscular dystrophy, exosomes secreted by the engineered fibroblasts improved exercise capacity and reduced skeletal-muscle fibrosis. We also demonstrate that exosomes from high-potency CDCs exhibit enhanced levels of miR-92a (a known potentiator of the Wnt/β-catenin pathway), and that they activate cardioprotective bone-morphogenetic-protein signalling in cardiomyocytes. Our findings show that the modulation of canonical Wnt signalling can turn therapeutically inert mammalian cells into immortal exosome factories for cell-free therapies.

Overexpression of β-catenin and the transcription factor Gata4 in skin fibroblasts converts them into therapeutically active cells that secrete reparative exosomes as shown in mice models of myocardial infarction and Duchenne muscular dystrophy.

Baicalein retards proliferation and collagen deposition by activating p38MAPK-JNK via microRNA-29

Immoderate proliferation and deposition of collagen generally result in hypertrophic scars and even keloids. microRNA-29 (miR-29) has been proved as a crucial regulator in these pathological processes. Although mounting evidence have proved baicalein (BAI) impairs scar formation, it is still incompletely understood whether miR-29 participated in the underlying mechanism. In the present study, NIH-3T3 cells were stimulated with BAI, and then cell viability was analyzed by cell counting kit-8 (CCK-8) and Western blot. We further analyzed total soluble collagen, collagen 1, and alpha-smooth muscle actin (α-SMA) in NIH-3T3 cells, which were exposed to transforming growth factor beta 1 (TGF-β1)/BAI, using a Sircol assay kit, quantitative reverse transcription-PCR (qRT-PCR) and Western blot, respectively. Besides, the miR-29 inhibitor was transduced and its transfection efficiency was verified by qRT-PCR. Finally, the phosphorylated p38 mitogen-activated protein kinase (p38MAPK) and c-Jun N-terminal kinase (JNK) were examined by Western blot. BAI effectively retarded NIH-3T3 proliferation in a dose-dependent manner. Besides, TGF-β1-induced deposition of total soluble collagen and synthesis of collagen 1 and α-SMA were repressed by BAI at mRNA and protein levels. However, miR-29 inhibitor reversed the effects of BAI. Remarkably, BAI promoted phosphorylated expression of p38MAPK and JNK while miR-29 inhibitor reversed its effects on the phosphorylated expression of p38MAPK and JNK. BAI effectively weakened the cell viability and repressed TGF-β1-induced total soluble collagen as well as collagen 1 and α-SMA by upregulating miR-29. Mechanically, BAI activates the p38MAPK/JNK pathway by promoting miR-29.

The Differential Expression of miRNAs and a Preliminary Study on the Mechanism of miR-194-3p in Keloids

The aim of this study was to detect abnormally expressed microRNA (miRNA) in keloids and to study their functions. The differential expression of miRNAs in keloids and normal tissue was detected by gene microarray. MiRNA expression was verified by real-time PCR. A luciferase reporter gene assay, western blot, and real-time PCR were used to detect the effect of miR-194-3p on RUNX2. An MTT assay and a transwell assay were used to detect the effect of miR-194-3p in both primary cultured fibroblasts and HKF cells. Related proteins were analysed by western blot and real-time PCR. The expression of miR-194-3p was lower in keloids, and MiR-194-3p was shown to target RUNX2 directly. MiR-194-3p inhibited the proliferation and migration of fibroblasts through the inhibition of CDK4 and MMP2. MiR-194-3p and RUNX2 may become new targets for the prevention and treatment of keloids.

miR-188-5p regulates proliferation and invasion via PI3K/Akt/MMP-2/9 signaling in keloids

Keloids (KDs) and hypertrophic scars (HSs), two forms of pathological scars, seriously affect the physical and psychological health of patients. Despite many similarities with HSs, KDs are characterized by invasion and a high rate of recurrence after surgery, features they share in common with tumors. The underlying molecular mechanisms of this phenomenon have not been fully elucidated. In this study, we used microRNA (miRNA) array analysis to search for invasion-associated miRNAs in KDs. The expression of miR-188-5p in KDs, HSs, normal skin (NS) tissues, and cell lines was measured by quantitative real-time polymerase chain reaction. Furthermore, cell proliferation, migration, and invasion were detected in KD fibroblasts (KFs) and HS fibroblasts (HSFs), and interrelated proteins were ascertained by western blot analysis. It was found that miR-188-5p was significantly decreased in KD tissue compared with HS and NS tissues. Upregulated expression of miR-188-5p suppressed KF proliferation, migration, and invasion; and decreased expression of miR-188-5p also promoted HSF proliferation, migration, and invasion. The protein levels of MMP-2, MMP-9, PI3K, and p-Akt in miR-188-5p mimic-transfected KFs were repressed. In contrast, after transfection with miR-188-5p inhibitor, the protein levels of MMP-2, MMP-9, PI3K, and p-Akt were higher than the control in HSFs. Treatment with PI3K/Akt inhibitor LY294002 in KFs with miR-188-5p inhibitor did not further reduce their proliferation, migration, and invasion. The upregulation of MMP-2 and MMP-9 by miR-188-5p inhibitor could be abolished by LY294002. These findings together demonstrate a tumor-suppressive role of miR-188-5p in KD proliferation and invasion via PI3K/Akt/MMP-2/9 signaling, indicating that miR-188-5p may be a potential prognostic marker and therapeutic target for KDs.

In vitro analysis of the role of tumor necrosis factor‑stimulated gene‑6 in keloid

An increasing number of studies have demonstrated that tumor necrosis factor-stimulated gene-6 (TSG-6) has a key role in the progression of fibrosis; however, the exact effects of TSG-6 in keloid fibroblasts (KFs) remain unknown. The aim of the current study was to investigate the role of TSG-6 in the pathogenesis of keloids. Primary fibroblasts from 10 patients with keloid were cultured and transfected with pLVX-Puro or pLVX-Puro-TSG-6. Alterations of TSG-6 expression were then determined by reverse transcription-polymerase chain reaction (RT-PCR) and regulation was observed in KFs transfected with pLVX-Puro-TSG-6. Compared with the control group, transfection with pLVX-Puro-TSG-6 induced growth suppression, cell apoptosis and G2/M arrest in KFs. In addition, the mitochondrial apoptosis pathway was activated in KFs transfected with pLVX-Puro-TSG-6. These findings indicate that TSG-6 is a novel regulator of keloid fibrogenesis, and thus could be used/targeted TSG-6 as a promising treatment for keloid.

A MicroRNA-29 Mimic (Remlarsen) Represses Extracellular Matrix Expression and Fibroplasia in the Skin

MicroRNA-29 (miR-29) negatively regulates fibrosis and is downregulated in multiple fibrotic organs and tissues, including in the skin. miR-29 mimics prevent pulmonary fibrosis in mouse models but have not previously been tested in the skin. This study aimed to identify pharmacodynamic biomarkers of miR-29 in mouse skin, to translate those biomarkers across multiple species, and to assess the pharmacodynamic activity of a miR-29b mimic (remlarsen) in a clinical trial. miR-29 biomarkers were selected based on gene function and mRNA expression using quantitative reverse transcriptase polymerase chain reaction. Those biomarkers comprised multiple collagens and other miR-29 direct and indirect targets and were conserved across species; remlarsen regulated their expression in mouse, rat, and rabbit skin wounds and in human skin fibroblasts in culture, while a miR-29 inhibitor reciprocally regulated their expression. Biomarker expression translated to clinical proof-of-mechanism; in a double-blinded, placebo-randomized, within-subject controlled clinical trial of single and multiple ascending doses of remlarsen in normal healthy volunteers, remlarsen repressed collagen expression and the development of fibroplasia in incisional skin wounds. These results suggest that remlarsen may be an effective therapeutic to prevent formation of a fibrotic scar (hypertrophic scar or keloid) or to prevent cutaneous fibrosis, such as scleroderma.

Downregulation of miR‑637 promotes proliferation and metastasis by targeting Smad3 in keloids

Keloids are a type of abnormal scar tissue. MicroRNAs (miRNAs) exhibit a pivotal role in the regulation of cell proliferation and metastasis of keloids. miRNA microarray revealed that miR‑637 was one of the most frequently altered miRNAs in keloids. Furthermore, up-regulation of miR‑637 inhibited cell proliferation and metastasis by targeting mothers against decapentaplegic homolog (Smad)3, one of the important proteins that affects the formation of keloids. Further studies demonstrated that miR‑637 regulated the proliferation and metastasis of human keloid fibroblast (HKF) cells by mediating the Smad3 signaling pathway. Overall, the present findings suggest that miR‑637 may be a promising therapeutic target in keloids.

Fibroproliferative genes are preferentially expressed in central centrifugal cicatricial alopecia

BACKGROUND

Central centrifugal cicatricial alopecia (CCCA) is a primary cicatricial alopecia that most commonly affects women of African descent. Like CCCA, fibroproliferative disorders (FPDs) such as keloids, atherosclerosis, and fibroids are characterized by low-grade inflammation and irritation, resulting in end-stage fibrosis.

OBJECTIVE

We sought to determine whether fibroproliferative genes were up-regulated in patients with CCCA.

METHODS

A total of 5 patients with biopsy-proven CCCA were recruited for this study. Two scalp biopsy specimens were obtained from each patient; 1 from CCCA-affected vertex scalp and 1 from the unaffected occipital scalp. Microarray analysis was performed to determine the differential gene expression patterns.

RESULTS

There was an upregulation of genes implicated in FPDs in patients with CCCA. Specifically, we noted increased expression of platelet derived growth factor gene (PDGF), collagen I gene (COL I), collagen III gene (COL III), matrix metallopeptidase 1 gene (MMP1), matrix metallopeptidase 2 gene (MMP2), matrix metallopeptidase 7 gene (MMP7), and matrix metallopeptidase 9 gene (MMP9) in affected scalp compared with in unaffected scalp. Significant overlap in the canonic pathways was noted between patients with CCCA and patients with both atherosclerosis and hepatic fibrosis (P < .001).

LIMITATIONS

Small sample size and the use of whole skin tissue for analysis.

CONCLUSION

We have identified the upregulation of critical genes implicated in FPDs in the gene expression profile of patients with CCCA. These findings may help identify future therapeutic targets for this otherwise difficult-to-treat condition.

Identification and functional analysis of inflammation-related miRNAs in skin wound repair

Inflammation at a wound site is essential for preventing infection. However, misregulated inflammation leads to pathologies of the healing process, including chronic non-healing wounds and scarring. MicroRNAs (miRNAs) are key regulators of the inflammatory response and tissue repair, acting by translational processing of target mRNAs. In the final step of miRNA processing, Argonaute 2 (Ago2)-bound mature miRNA complexes bind to target mRNAs and inhibit their translation. A variety of wound healing-related miRNAs have been identified and their misregulation likely contributes to wound pathologies, including scarring and chronic healing. Recently, we have developed an Ago2-bound mature miRNA purification system that uses Ago2 antibody to analyze the expression of miRNAs from wound tissues by microarray and next generation sequencing. We have identified several wound inflammation-related miRNAs via Ago2-target immunoprecipitation assays and next generation sequencing of wound tissues from wild-type and PU.1 knockout mice, which exhibit no inflammatory response because of a lack of immune cell lineages. We demonstrated that miR-142, an identified inflammation-related miRNA, is essential role for neutrophilic chemotaxis via inhibition of small GTPase translation; its misregulation leads to susceptibility to infection against Staphylococcus aureus at skin wound sites. In this review, we summarize recent advances of miRNA studies in skin wound healing, introduce our miRNA purification system using an immunoprecipitation assay method, and discuss the function of miR-142 in skin wound healing.

Impact of Transcriptomics on Our Understanding of Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a lethal fibrotic lung disease characterized by aberrant remodeling of the lung parenchyma with extensive changes to the phenotypes of all lung resident cells. The introduction of transcriptomics, genome scale profiling of thousands of RNA transcripts, caused a significant inversion in IPF research. Instead of generating hypotheses based on animal models of disease, or biological plausibility, with limited validation in humans, investigators were able to generate hypotheses based on unbiased molecular analysis of human samples and then use animal models of disease to test their hypotheses. In this review, we describe the insights made from transcriptomic analysis of human IPF samples. We describe how transcriptomic studies led to identification of novel genes and pathways involved in the human IPF lung such as: matrix metalloproteinases, WNT pathway, epithelial genes, role of microRNAs among others, as well as conceptual insights such as the involvement of developmental pathways and deep shifts in epithelial and fibroblast phenotypes. The impact of lung and transcriptomic studies on disease classification, endotype discovery, and reproducible biomarkers is also described in detail. Despite these impressive achievements, the impact of transcriptomic studies has been limited because they analyzed bulk tissue and did not address the cellular and spatial heterogeneity of the IPF lung. We discuss new emerging technologies and applications, such as single-cell RNAseq and microenvironment analysis that may address cellular and spatial heterogeneity. We end by making the point that most current tissue collections and resources are not amenable to analysis using the novel technologies. To take advantage of the new opportunities, we need new efforts of sample collections, this time focused on access to all the microenvironments and cells in the IPF lung.

Insights into the key roles of epigenetics in matrix macromolecules-associated wound healing

Extracellular matrix (ECM) is a dynamic network of macromolecules, playing a regulatory role in cell functions, tissue regeneration and remodeling. Wound healing is a tissue repair process necessary for the maintenance of the functionality of tissues and organs. This highly orchestrated process is divided into four temporally overlapping phases, including hemostasis, inflammation, proliferation and tissue remodeling. The dynamic interplay between ECM and resident cells exerts its critical role in many aspects of wound healing, including cell proliferation, migration, differentiation, survival, matrix degradation and biosynthesis. Several epigenetic regulatory factors, such as the endogenous non-coding microRNAs (miRNAs), are the drivers of the wound healing response. microRNAs have pivotal roles in regulating ECM composition during wound healing and dermal regeneration. Their expression is associated with the distinct phases of wound healing and they serve as target biomarkers and targets for systematic regulation of wound repair. In this article we critically present the importance of epigenetics with particular emphasis on miRNAs regulating ECM components (i.e. glycoproteins, proteoglycans and matrix proteases) that are key players in wound healing. The clinical relevance of miRNA targeting as well as the delivery strategies designed for clinical applications are also presented and discussed.

MicroRNA-29: A Crucial Player in Fibrotic Disease

Fibrosis is a common pathological state characterized by the excessive accumulation of extracellular matrix components, but the pathogenesis of the disease is still not clear. Previous studies have shown that microRNA-29 (miR-29) can play pivotal roles in the regulation of a variety of organ fibrosis, including cardiac fibrosis, hepatic fibrosis, lung fibrosis, systemic sclerosis, and keloid. In this review, we outline the structure, expression, and regulation of miR-29 as well as its role in fibrotic diseases.

Downregulation of microRNA-31 inhibits proliferation and induces apoptosis by targeting HIF1AN in human keloid

microRNAs (miRNAs) play a pivotal role in the regulation of cell proliferation and apoptosis in keloid scarring. Integrative analysis of the previous miRNA microarray revealed miRNA-31 was among the most frequently altered miRNAs in keloid and hypertrophic scar. Using qRT-PCR, we further validated miRNA-31 was increased in keloid tissues and keloid-derived fibroblasts. Moreover, downregulation of miRNA-31 inhibited the cell proliferation, induced the cell apoptosis and disturbed the cell cycle progression by targeting HIF1AN, a negative modulator of hypoxia inducible factor 1. Through the luciferase reporter assay, HIF1AN was confirmed to be a target of miRNA-31. Further studies demonstrated that miRNA-31 regulated proliferation, apoptosis and cell cycle of keloid-derived fibroblasts by mediating HIF1AN/VEGF signaling pathway. Overall, our findings shed new light on miRNA-31 as a promising therapeutic target in keloid scarring.

Role of the microRNA-29 family in fibrotic skin diseases

Fibrotic skin diseases are characterized by the accumulation of collagen. The hallmarks of fibrotic skin diseases are unbalanced fibroblast proliferation and differentiation, extracellular matrix production and transforming growth factor-β signalling. Numerous studies have investigated the possibility that microRNAs (miRNAs or miRs) are involved in the pathogenesis of certain fibrotic diseases, including skin, heart, lung and liver diseases. miRNAs are a class of small non-coding RNAs, which modify gene expression by binding to target messenger RNA (mRNA) and blocking the translation or inducing the degradation of target mRNA. The biological relevance of miRNAs has been investigated in physiological and pathological conditions, and there is increasing evidence that the miR-29 family is associated with fibrotic diseases. The aim of the present review is to provide an up-to-date summary of current knowledge on the latest developments associated with the miR-29 family and fibrotic skin diseases.

Non-Coding RNAs: New Players in Skin Wound Healing

Significance: Wound healing is a basic physiological process that is utilized to keep the integrity of the skin. Impaired wound repair, such as chronic wounds and pathological scars, presents a major health and economic burden worldwide. To date, efficient targeted treatment for these wound disorders is still lacking, which is largely due to our limited understanding of the biological mechanisms underlying these diseases. Research driven around discovering new therapies for these complications is, therefore, an urgent need. Recent Advances: The vast majority of the human genome is transcribed to RNAs that lack protein-coding capacity. Intensive research in the recent decade has revealed that these non-coding RNAs (ncRNAs) function as important regulators of cellular physiology and pathology, which makes them promising therapeutic and diagnostic entities. Critical Issues: A class of short ncRNAs, microRNAs, has been found to be indispensable for all the phases of skin wound healing and plays important roles in the pathogenesis of wound complications. The role of long ncRNAs (lncRNA) in skin wound healing remains largely unexplored. Recent studies revealed the essential role of lncRNAs in epidermal differentiation and stress response, indicating their potential importance for skin wound healing, which warrants future research. Future Directions: An investigation of ncRNAs will add new layers of complexity to our understanding of normal skin wound healing as well as to the pathogenesis of wound disorders. Development of ncRNA-based biomarkers and treatments is an interesting and important avenue for future research on wound healing.

From genetics to epigenetics: new insights into keloid scarring

Keloid scarring is a dermal fibroproliferative response characterized by excessive and progressive deposition of collagen; aetiology and molecular pathology underlying keloid formation and progression remain unclear. Genetic predisposition is important in the pathogenic processes of keloid formation, however, environmental factors and epigenetic mechanisms may also play pivotal roles. Epigenetic modification is a recent area of investigation in understanding the molecular pathogenesis of keloid scarring and there is increasing evidence that epigenetic changes may play a role in induction and persistent activation of fibroblasts in keloid scars. Here we have reviewed three epigenetic mechanisms: DNA methylation, histone modification and the role of non-coding RNAs. We also review the evidence that these mechanisms may play a role in keloid formation - in future, it may be possible that epigenetic markers may be used instead of prognostic or diagnostic markers here. However, there is a significant amount of work required to increase our current understanding of the role of epigenetic modification in keloid disease.