MicroRNA-145-5p regulates fibrotic features of recessive dystrophic epidermolysis bullosa skin fibroblasts

miR-145-enriched BMSCs-derived exosomes ameliorate neurogenic erectile dysfunction in aged rats via TGFBR2 inhibition

Background

Neurogenic erectile dysfunction (ED) is a prevalent complication following radical prostatectomy in elderly patients, primarily resulting from the apoptosis of corpus cavernosum smooth muscle cells (CCSMCs) and the subsequent excessive fibrosis of the corpus cavernosum.

Aim

This study aimed to compare the therapeutic effects of exosomes derived from lentivirus-transfected miR-145 bone marrow mesenchymal stem cells (Exo-145) and unmodified BMSCs-derived exosomes (Exo) in aged rats with bilateral cavernous nerve injury (BCNI) and investigate the underlying mechanisms.

Methods

Twenty-four-month-old male rats were assigned to four groups, namely Sham, BCNI, Exo, and Exo-145. Three weeks after treatment, erectile function was assessed by measuring the maximal intracavernosal pressure to mean arterial pressure (ICP/MAP) ratio. Apoptosis and fibrosis were semi-quantitatively analyzed using TUNEL and Masson's trichrome staining, respectively. In vitro, CCSMCs were subjected to H2O2-induced oxidative stress, and the protective effects of Exo-145 were evaluated through flow cytometry and Western blot. Lastly, the targets and mechanisms of miR-145 were further validated using dual-luciferase reporter assays and rescue experiments.

Results

Exo-145 significantly outperformed Exo in restoring erectile function in aged BCNI rats, as evidenced by the significantly higher maximal ICP/MAP ratio, a marked reduction in TUNEL-positive cell count, and marked suppression of fibrosis in cavernous tissue. Moreover, Masson's trichrome staining displayed a substantial decrease in collagen deposition. In vitro, Exo-145 alleviated H2O2-induced apoptosis in CCSMCs by downregulating Cleaved Caspase-3 expression and Bax while concurrently upregulating Bcl-2 expression. TGFBR2 was identified as a direct target of miR-145 through dual-luciferase reporter assays, with its overexpression partially reversing the protective effects of Exo-145.

Conclusion

Exo-145 demonstrates superior efficacy compared to Exo in treating aged neurogenic ED by targeting TGFBR2 to alleviate apoptosis and fibrosis. It may represent a promising cell-free therapeutic option for neurogenic erectile dysfunction in elderly patients and could offer new perspectives for improving their prognosis.

Dystrophic epidermolysis bullosa - From biochemistry to interventions

The skin, as a barrier organ meeting constant mechanical challenges, is equipped with multiple adhesive structures that collectively support resilient, yet flexible attachment of its epithelium -the epidermis to its mesenchyme - the dermis. One such structure is the collagen VII-composed anchoring fibril, which provides firm anchorage of the epidermal basement membrane to the underlying interstitial extracellular matrix. Blistering and wider tissue fragility in the genetic disease dystrophic epidermolysis bullosa (DEB) caused by collagen VII deficiency illustrate the essential function of collagen VII in supporting skin integrity. DEB is also a progressive inflammatory fibrotic disease with multi-organ involvement, indicating that collagen VII has broader functions than simply providing epithelial anchorage. This review explores the reciprocal relationship between collagen VII biology and DEB pathophysiology. A deeper understanding of collagen VII biology - spanning its synthesis, assembly into suprastructures, and regulatory roles - enhances our understanding of DEB. Conversely, detailed insights into DEB through analysis of disease progression or therapeutic interventions offer valuable information on the broader tissue and organismal roles of collagen VII in maintaining homeostasis. This review focuses on such knowledge exchange in advancing our understanding of collagen VII, the extracellular matrix in general, and inspiring potential strategies for treatment of DEB. Importantly, in a broader sense, the discussed themes are applicable to other conditions driven by compromised extracellular matrix instruction and integrity, leading to progressive damage and inflammation.

Gamma-Secretase Inhibitors Downregulate the Profibrotic NOTCH Signaling Pathway in Recessive Dystrophic Epidermolysis Bullosa

Recessive dystrophic epidermolysis bullosa (RDEB) is a rare skin fragility disorder caused by mutations in COL7A1. RDEB is hallmarked by trauma-induced unremitting blistering, chronic wounds with inflammation, and progressive fibrosis, leading to severe disease complications. There is currently no cure for RDEB-associated fibrosis. Our previous studies and increasing evidence highlighted the profibrotic role of NOTCH pathway in different skin disorders, including RDEB. In this study, we further investigated the role of NOTCH signaling in RDEB pathogenesis and explored the effects of its inhibition by γ-secretase inhibitors DAPT and PF-03084014 (nirogacestat). Our analyses demonstrated that JAG1 and cleaved NOTCH1 are upregulated in primary RDEB fibroblasts (ie, RDEB-derived fibroblasts) compared with controls, and their protein levels are further increased by TGF-β1 stimulation. Functional assays unveiled the involvement of JAG1/NOTCH1 axis in RDEB fibrosis and demonstrated that its blockade counteracts a variety of fibrotic traits. In particular, RDEB-derived fibroblasts treated with PF-03084014 showed (i) a significant reduction of contractility, (ii) a diminished secretion of TGF-β1 and collagens, and (iii) the downregulation of several fibrotic proteins. Although less marked than PF-03084014-treated cells, RDEB-derived fibroblasts exhibited a reduction of fibrotic traits also upon DAPT treatment. This study provides potential therapeutic strategies to antagonize RDEB fibrosis onset and progression.

Head-to-head comparison of relevant cell sources of small extracellular vesicles for cardiac repair: Superiority of embryonic stem cells

Small extracellular vesicles (sEV) derived from various cell sources have been demonstrated to enhance cardiac function in preclinical models of myocardial infarction (MI). The aim of this study was to compare different sources of sEV for cardiac repair and determine the most effective one, which nowadays remains limited. We comprehensively assessed the efficacy of sEV obtained from human primary bone marrow mesenchymal stromal cells (BM-MSC), human immortalized MSC (hTERT-MSC), human embryonic stem cells (ESC), ESC-derived cardiac progenitor cells (CPC), human ESC-derived cardiomyocytes (CM), and human primary ventricular cardiac fibroblasts (VCF), in in vitro models of cardiac repair. ESC-derived sEV (ESC-sEV) exhibited the best pro-angiogenic and anti-fibrotic effects in vitro. Then, we evaluated the functionality of the sEV with the most promising performances in vitro, in a murine model of MI-reperfusion injury (IRI) and analysed their RNA and protein compositions. In vivo, ESC-sEV provided the most favourable outcome after MI by reducing adverse cardiac remodelling through down-regulating fibrosis and increasing angiogenesis. Furthermore, transcriptomic, and proteomic characterizations of sEV derived from hTERT-MSC, ESC, and CPC revealed factors in ESC-sEV that potentially drove the observed functions. In conclusion, ESC-sEV holds great promise as a cell-free treatment for promoting cardiac repair following MI.

P-MSC-derived extracellular vesicles facilitate diabetic wound healing via miR-145-5p/ CDKN1A-mediated functional improvements of high glucose-induced senescent fibroblasts

Background

Persistent hyperglycaemia in diabetes causes functional abnormalities of human dermal fibroblasts (HDFs), partially leading to delayed skin wound healing. Extracellular vesicles (EVs) containing multiple pro-healing microRNAs (miRNAs) have been shown to exert therapeutic effects on diabetic wound healing. The present study aimed to observe the effects of EVs derived from placental mesenchymal stem cells (P-MSC-EVs) on diabetic wound healing and high glucose (HG)-induced senescent fibroblasts and to explore the underlying mechanisms.

Methods

P-MSC-EVs were isolated by differential ultracentrifugation and locally injected into the full-thickness skin wounds of diabetic mice, to observe the beneficial effects on wound healing in vivo by measuring wound closure rates and histological analysis. Next, a series of assays were conducted to evaluate the effects of low (2.28 x 1010 particles/ml) and high (4.56 x 1010 particles/ml) concentrations of P-MSC-EVs on the senescence, proliferation, migration, and apoptosis of HG-induced senescent HDFs in vitro. Then, miRNA microarrays and real-time quantitative PCR (RT-qPCR) were carried out to detect the differentially expressed miRNAs in HDFs after EVs treatment. Specific RNA inhibitors, miRNA mimics, and small interfering RNA (siRNA) were used to evaluate the role of a candidate miRNA and its target genes in P-MSC-EV-induced improvements in the function of HG-induced senescent HDFs.

Results

Local injection of P-MSC-EVs into diabetic wounds accelerated wound closure and reduced scar widths, with better-organized collagen deposition and decreased p16INK4a expression. In vitro, P-MSC-EVs enhanced the antisenescence, proliferation, migration, and antiapoptotic abilities of HG-induced senescent fibroblasts in a dose-dependent manner. MiR-145-5p was found to be highly enriched in P-MSC-EVs. MiR-145-5p inhibitors effectively attenuated the P-MSC-EV-induced functional improvements of senescent fibroblasts. MiR-145-5p mimics simulated the effects of P-MSC-EVs on functional improvements of fibroblasts by suppressing the expression of cyclin-dependent kinase inhibitor 1A and activating the extracellular signal regulated kinase (Erk)/protein kinase B (Akt) signaling pathway. Furthermore, local application of miR-145-5p agomir mimicked the effects of P-MSC-EVs on wound healing.

Conclusions

These results suggest that P-MSC-EVs accelerate diabetic wound healing by improving the function of senescent fibroblasts through the transfer of miR-145-5p, which targets cyclin-dependent kinase inhibitor 1A to activate the Erk/Akt signaling pathway. P-MSC-EVs are promising therapeutic candidates for diabetic wound treatment.

Biomarker Discovery in Rare Malignancies: Development of a miRNA Signature for RDEB-cSCC

Machine learning has been proven to be a powerful tool in the identification of diagnostic tumor biomarkers but is often impeded in rare cancers due to small patient numbers. In patients suffering from recessive dystrophic epidermolysis bullosa (RDEB), early-in-life development of particularly aggressive cutaneous squamous-cell carcinomas (cSCCs) represents a major threat and timely detection is crucial to facilitate prompt tumor excision. As miRNAs have been shown to hold great potential as liquid biopsy markers, we characterized miRNA signatures derived from cultured primary cells specific for the potential detection of tumors in RDEB patients. To address the limitation in RDEB-sample accessibility, we analyzed the similarity of RDEB miRNA profiles with other tumor entities derived from the Cancer Genome Atlas (TCGA) repository. Due to the similarity in miRNA expression with RDEB-SCC, we used HN-SCC data to train a tumor prediction model. Three models with varying complexity using 33, 10 and 3 miRNAs were derived from the elastic net logistic regression model. The predictive performance of all three models was determined on an independent HN-SCC test dataset (AUC-ROC: 100%, 83% and 96%), as well as on cell-based RDEB miRNA-Seq data (AUC-ROC: 100%, 100% and 91%). In addition, the ability of the models to predict tumor samples based on RDEB exosomes (AUC-ROC: 100%, 93% and 100%) demonstrated the potential feasibility in a clinical setting. Our results support the feasibility of this approach to identify a diagnostic miRNA signature, by exploiting publicly available data and will lay the base for an improvement of early RDEB-SCC detection.

Expression of microRNAs in leukocytes and serum of asbestosis patients

BACKGROUND

Although asbestos use is banned in many countries, long latency of asbestos-related diseases like pleural plaques or asbestosis mean it is still a public health issue. People suffering from these diseases have a higher risk of developing mesothelioma or lung cancer, which can progress quickly and aggressively. MicroRNAs were suggested as potential biomarkers in several diseases. However, in asbestosis, blood microRNAs are less explored. Since miR-32-5p, miR-143-3p, miR-145-5p, miR-146b-5p, miR-204-5p and miR-451a are involved in fibrotic processes and in cancer, expression of these microRNAs was analyzed in leukocytes and serum of asbestosis patients.

METHODS

MicroRNA expression was analyzed in leukocytes and serum of 36 patients (26 affected by pleural plaques and 10 by asbestosis) and 15 healthy controls by real-time RT-PCR. Additionally, data analyses were performed regarding disease severity based on ILO classification.

RESULTS

MicroRNA miR-146b-5p was significantly down-regulated in leukocytes of patients suffering from pleural plaques with a large effect indicated by η²_p = 0.150 and Cohen's f = 0.42, a value of difference of 0.725 and a 95% confidence interval of 0.070-1.381. In patients suffering from asbestosis miR-146b-5p was not significantly regulated. However, data analyses considering disease severity only, revealed that miR-146b-5p was significantly down-regulated in leukocytes of mildly diseased patients compared to controls with a large effect indicated by η²_p = 0.178 and Cohen's f = 0.465, a value of difference of 0.848 and a 95% confidence interval of 0.097-1.599. Receiver operating characteristic (ROC) curve and an area under the ROC curve value of 0.757 for miR-146b-5p indicated acceptable discrimination ability between patients suffering from pleural plaques and healthy controls. Less microRNAs were detectable in serum than in leukocytes, showing no significant expression differences in all participants of this study. Moreover, miR-145-5p was regulated significantly differently in leukocytes and serum. An R² value of 0.004 for miR-145-5p indicated no correlation in microRNA expression between leukocytes and serum.

CONCLUSION

Leukocytes seem more suitable than serum for microRNA analyses regarding disease and potentially cancer risk assessment of patients suffering from asbestos-related pleural plaques or asbestosis. Long-term studies may reveal whether down-regulation of miR-146b-5p in leukocytes might be an early indicator for an increased cancer risk.

Maintenance of chronicity signatures in fibroblasts isolated from recessive dystrophic epidermolysis bullosa chronic wound dressings under culture conditions

BACKGROUND

Recessive Dystrophic Epidermolysis Bullosa (RDEB) is a rare inherited skin disease caused by variants in the COL7A1 gene, coding for type VII collagen (C7), an important component of anchoring fibrils in the basement membrane of the epidermis. RDEB patients suffer from skin fragility starting with blister formation and evolving into chronic wounds, inflammation and skin fibrosis, with a high risk of developing aggressive skin carcinomas. Restricted therapeutic options are limited by the lack of in vitro models of defective wound healing in RDEB patients.

RESULTS

In order to explore a more efficient, non-invasive in vitro model for RDEB studies, we obtained patient fibroblasts derived from discarded dressings) and examined their phenotypic features compared with fibroblasts derived from non-injured skin of RDEB and healthy-donor skin biopsies. Our results demonstrate that fibroblasts derived from RDEB chronic wounds (RDEB-CW) displayed characteristics of senescent cells, increased myofibroblast differentiation, and augmented levels of TGF-β1 signaling components compared to fibroblasts derived from RDEB acute wounds and unaffected RDEB skin as well as skin from healthy-donors. Furthermore, RDEB-CW fibroblasts exhibited an increased pattern of inflammatory cytokine secretion (IL-1β and IL-6) when compared with RDEB and control fibroblasts. Interestingly, these aberrant patterns were found specifically in RDEB-CW fibroblasts independent of the culturing method, since fibroblasts obtained from dressing of acute wounds displayed a phenotype more similar to fibroblasts obtained from RDEB normal skin biopsies.

CONCLUSIONS

Our results show that in vitro cultured RDEB-CW fibroblasts maintain distinctive cellular and molecular characteristics resembling the inflammatory and fibrotic microenvironment observed in RDEB patients' chronic wounds. This work describes a novel, non-invasive and painless strategy to obtain human fibroblasts chronically subjected to an inflammatory and fibrotic environment, supporting their use as an accessible model for in vitro studies of RDEB wound healing pathogenesis. As such, this approach is well suited to testing new therapeutic strategies under controlled laboratory conditions.

Combination Treatment with Hydroxytyrosol and Vitamin E Improves NAFLD-Related Fibrosis

Non-alcoholic fatty liver disease (NAFLD)-related liver fibrosis results in the encapsulation of injured liver parenchyma by a collagenous scar mainly imputable to hepatic stellate cells’ activation. Approved pharmacological treatments against NAFLD-related fibrosis are still lacking, but natural compounds such as hydroxytyrosol (HXT) and vitamin E (VitE), are emerging as promising therapeutic opportunities. In this study, the potential anti-fibrotic effect of HXT + VitE combination therapy was investigated in vitro and in vivo. In particular, tumor growth factor (TGF)-β-activated LX-2 cells as an in vitro model, and carbon tetrachloride plus a Western diet as a mice model were employed. The effect of HXT + VitE on fibrosis was also investigated in children with biopsy-proven NAFLD. Our results demonstrated that HXT + VitE caused a reduction of proliferation, migration, contractility, and expression of pro-fibrogenic genes in TGF-β-activated LX-2 cells. HXT + VitE treatment also antagonized TGF-β-dependent upregulation of pro-oxidant NOX2 by interfering with nuclear translocation/activation of SMAD2/3 transcription factors. The mouse model of NAFLD-related fibrosis treated with HXT + VitE showed a marked reduction of fibrosis pattern by histology and gene expression. Accordingly, in children with NAFLD, HXT + VitE treatment caused a decrease of circulating levels of PIIINP and NOX2 that was supported over time. Our study suggests that HXT + VitE supplementation may improve NAFLD-related fibrosis.

Identification and characterization of four immune-related signatures in keloid

A keloid is a fibroproliferative disorder of unknown etiopathogenesis that requires ill-defined treatment. Existing evidence indicates that the immune system plays an important role in the occurrence and development of keloid. However, there is still a lack of research on the immune-related signatures of keloid. Here we identified immune-related signatures in keloid and explored their pathological mechanisms. Transcriptomic datasets (GSE7890, GSE92566, and GSE44270) of keloid and normal skin tissues were obtained from the Gene Expression Omnibus database. The overlap of differentially expressed genes and immune-related genes was considered as differentially expressed immune-related genes (DEIGs). Functional analysis, expression, and distribution were applied to explore the function and characteristics of DEIGs, and the expression of these DEIGs in keloid and normal skin tissues was verified by immunohistochemistry. Finally, we conducted interactive network analysis and immune infiltration analysis to determine the therapeutic potential and immune correlation. We identified four DEIGs (LGR5, PTN, JAG1, and DKK1). In these datasets, only GSE7890 met the screening criteria. In the GSE7890 dataset, DKK1 and PTN were downregulated in keloid, whereas JAG1 and LGR5 were upregulated in keloid. In addition, we obtained the same conclusion through immunohistochemistry. Functional analysis indicated that these four DEIGs were mainly involved in stem cell, cell cycle, UV response, and therapy resistance. Through interactive network analysis, we found that these DEIGs were associated with drugs currently used to treat keloid, such as hydrocortisone, androstanolone, irinotecan, oxaliplatin, BHQ-880, and lecoleucovorin. Finally, many immune cells, including CD8⁺ T cells, resting memory CD4⁺ T cells, and M1 macrophages, were obtained by immune infiltration analysis. In conclusion, we identified four immune signaling molecules associated with keloid (LGR5, PTN, JAG1, and DKK1). These immune-related signaling molecules may be important modules in the pathogenesis of keloid. Additionally, we developed novel therapeutic targets for the treatment of this challenging disease.

Mechanistic interrogation of mutation-independent disease modulators of RDEB identifies the small leucine-rich proteoglycan PRELP as a TGF-β antagonist and inhibitor of fibrosis

Recessive dystrophic epidermolysis bullosa (RDEB) is a genetic extracellular matrix disease caused by deficiency in type VII collagen (Col VII). The disease manifests with devastating mucocutaneous fragility leading to progressive fibrosis and metastatic squamous cell carcinomas. Although collagen VII abundance is considered the main predictor of symptom course, previous studies have revealed the existence of mutation-independent mechanisms that control disease progression. Here, to investigate and validate new molecular modifiers of wound healing and fibrosis in a natural human setting, and toward development of disease-modulating treatment of RDEB, we performed gene expression profiling of primary fibroblast from RDEB siblings with marked phenotypic variations, despite having equal COL7A1 genotype. Gene enrichment analysis suggested that severe RDEB was associated with enhanced response to TGF-β stimulus, oxidoreductase activity, and cell contraction. Consistently, we found an increased response to TGF-β, higher levels of basal and induced reactive oxygen species (ROS), and greater contractile ability in collagen lattices in RDEB fibroblasts (RDEBFs) from donors with severe RDEB vs mild RDEB. Treatment with antioxidants allowed a reduction of the pro-fibrotic and contractile phenotype. Importantly, our analyses revealed higher expression and deposition in skin of the relatively uncharacterized small leucine-rich extracellular proteoglycan PRELP/prolargin associated with milder RDEB manifestations. Mechanistic investigations showed that PRELP effectively attenuated fibroblasts' response to TGF-β1 stimulus and cell contractile capacity. Moreover, PRELP overexpression in RDEBFs enhanced RDEB keratinocyte attachment to fibroblast-derived extracellular matrix in the absence of Col VII. Our results highlight the clinical relevance of pro-oxidant status and hyper-responsiveness to TGF-β in RDEB severity and progression. Of note, our study also reveals PRELP as a novel and natural TGF-β antagonist with a likely dermo-epidermal pro-adhesive capacity.

Revealing the role of miRNA-489 as a new onco-suppressor factor in different cancers based on pre-clinical and clinical evidence

Recently, microRNAs (miRNAs) have shown to be potential therapeutic, diagnostic and prognostic targets in disease therapy. These endogenous non-coding RNAs contribute to regulation of different cellular events that are necessary for maintaining physiological condition. Dysregulation of miRNAs is correlated with development of various pathological events such as neurological disorders, cardiovascular diseases, and cancer. miRNA-489 is a new emerging miRNA and studies are extensively investigating its role in pathological conditions. Herein, potential function of miRNA-489 as tumor-suppressor in various cancers is described. miRNA-489 is able to sensitize cancer cells into chemotherapy by disrupting molecular pathways involved in cancer growth such as PI3K/Akt, and induction of apoptosis. The PROX1 and SUZ12 as oncogenic pathways, are affected by miRNA-489 in suppressing metastasis of cancer cells. Wnt/β-catenin as an oncogenic factor ensuring growth and malignancy of tumors is inhibited via miRNA-489 function. For enhancing drug sensitivity of tumors, restoring miRNA-489 expression is a promising strategy. The lncRNAs can modulate miRNA-489 expression in tumors and studies about circRNA role in miRNA-489 modulation should be performed. The expression level of miRNA-489 is a diagnostic tool for tumor detection. Besides, down-regulation of miRNA-489 in tumors provides unfavorable prognosis.

Notch-ing up knowledge on molecular mechanisms of skin fibrosis: focus on the multifaceted Notch signalling pathway

Fibrosis can be defined as an excessive and deregulated deposition of extracellular matrix proteins, causing loss of physiological architecture and dysfunction of different tissues and organs. In the skin, fibrosis represents the hallmark of several acquired (e.g. systemic sclerosis and hypertrophic scars) and inherited (i.e. dystrophic epidermolysis bullosa) diseases. A complex series of interactions among a variety of cellular types and a wide range of molecular players drive the fibrogenic process, often in a context-dependent manner. However, the pathogenetic mechanisms leading to skin fibrosis are not completely elucidated. In this scenario, an increasing body of evidence has recently disclosed the involvement of Notch signalling cascade in fibrosis of the skin and other organs. Despite its apparent simplicity, Notch represents one of the most multifaceted, strictly regulated and intricate pathways with still unknown features both in health and disease conditions. Starting from the most recent advances in Notch activation and regulation, this review focuses on the pro-fibrotic function of Notch pathway in fibroproliferative skin disorders describing molecular networks, interplay with other pro-fibrotic molecules and pathways, including the transforming growth factor-β1, and therapeutic strategies under development.

MicroRNAs in pemphigus and pemphigoid diseases

Autoimmune blistering diseases are a heterogenous group of dermatological disorders characterized by blisters and erosions of the skin and/or mucous membranes induced by autoantibodies against structural proteins of the desmosome or the dermal-epidermal adhesion complex including the hemidesmosome. They consist of the two major disease groups, pemphigus and pemphigoid diseases (PPDs). The diagnosis is based on clinical findings, histopathology, direct immunofluorescence, and detection of circulating autoantibodies. The pathogenesis is not fully elucidated, prognostic factors are lacking, and to date, there is no cure for PPDs. MicroRNAs (miRNAs) represent small, non-coding RNAs that play a pivotal role in the posttranscriptional regulation of gene expression. Their dysfunction was highlighted to play a significant role in the pathogenesis of various diseases. Even though a link between miRNAs and autoimmune blistering diseases had been suggested, the research of their involvement in the pathogenesis of PPDs is still in its infancy. miRNAs hold promise for uncovering new layers in the pathogenesis of PPDs, in order to improve diagnosis and also to develop potential therapeutic options. In the current article, we provide an overview regarding current knowledge of miRNAs in terms of complex pathogenesis of PPDs, and, also, their potential role as biomarkers, predictive factors and therapeutic targets.

Epigenetic and metabolic regulation of epidermal homeostasis

Continuous exposure of the skin to environmental, mechanical and chemical stress necessitates constant self‐renewal of the epidermis to maintain its barrier function. This self‐renewal ability is attributed to epidermal stem cells (EPSCs), which are long‐lived, multipotent cells located in the basal layer of the epidermis. Epidermal homeostasis – coordinated proliferation and differentiation of EPSCs – relies on fine‐tuned adaptations in gene expression which in turn are tightly associated with specific epigenetic signatures and metabolic requirements. In this review, we will briefly summarize basic concepts of EPSC biology and epigenetic regulation with relevance to epidermal homeostasis. We will highlight the intricate interplay between mitochondrial energy metabolism and epigenetic events – including miRNA‐mediated mechanisms – and discuss how the loss of epigenetic regulation and epidermal homeostasis manifests in skin disease. Discussion of inherited epidermolysis bullosa (EB) and disorders of cornification will focus on evidence for epigenetic deregulation and failure in epidermal homeostasis, including stem cell exhaustion and signs of premature ageing. We reason that the epigenetic and metabolic component of epidermal homeostasis is significant and warrants close attention. Charting epigenetic and metabolic complexities also represents an important step in the development of future systemic interventions aimed at restoring epidermal homeostasis and ameliorating disease burden in severe skin conditions.

MicroRNA-489-3p Represses Hepatic Stellate Cells Activation by Negatively Regulating the JAG1/Notch3 Signaling Pathway

BACKGROUND

The transformation of hepatic stellate cells (HSCs) into collagen-producing myofibroblasts is a key event in hepatic fibrogenesis. Recent studies have shown that microRNAs (miRNAs) play a critical role in the transformation of HSCs. However, the function of miR-489-3p in liver fibrosis remains unclear.

METHODS

Here, we detected the levels of miR-489-3p and jagged canonical Notch ligand 1 (JAG1) in liver fibrosis by using CCl4-treated rats as an in vivo model and transforming growth factor-beta 1 (TGF-β1)-treated HSC cell lines LX-2 and HSC-T6 as in vitro models. The expression of profibrotic markers was affected by transfecting LX-2 cells with either miR-489-3p mimic or si-JAG1. A dual-luciferase reporter assay was carried out to study the interaction of JAG1 with miR-489-3p.

RESULTS

We found that miR-489-3p was remarkably decreased while JAG1 was increased in liver fibrosis models both in vivo and in vitro. Overexpression of miR-489-3p reduced the expression of profibrotic markers and the activation of LX-2 cells induced by TGF-β1. Moreover, miR-489-3p decreased the expression of jagged canonical Notch ligand 1 (JAG1) in LX-2 cells by interacting with its 3'-UTR. As JAG1 is a Notch ligand, decreased JAG1 by miR-489-3p inhibited the Notch signaling pathway. Moreover, the downregulation of JAG1 inhibited the expression of fibrotic markers.

CONCLUSION

Our results indicate that miR-489-3p can inhibit HSC activation by inhibiting the JAG1/Notch3 signaling pathway.

Epidermolysis Bullosa-Associated Squamous Cell Carcinoma: From Pathogenesis to Therapeutic Perspectives

Epidermolysis bullosa (EB) is a heterogeneous group of inherited skin disorders determined by mutations in genes encoding for structural components of the cutaneous basement membrane zone. Disease hallmarks are skin fragility and unremitting blistering. The most disabling EB (sub)types show defective wound healing, fibrosis and inflammation at lesional skin. These features expose patients to serious disease complications, including the development of cutaneous squamous cell carcinomas (SCCs). Almost all subjects affected with the severe recessive dystrophic EB (RDEB) subtype suffer from early and extremely aggressive SCCs (RDEB-SCC), which represent the first cause of death in these patients. The genetic determinants of RDEB-SCC do not exhaustively explain its unique behavior as compared to low-risk, ultraviolet-induced SCCs in the general population. On the other hand, a growing body of evidence points to the key role of tumor microenvironment in initiation, progression and spreading of RDEB-SCC, as well as of other, less-investigated, EB-related SCCs (EB-SCCs). Here, we discuss the recent advances in understanding the complex series of molecular events (i.e., fibrotic, inflammatory, and immune processes) contributing to SCC development in EB patients, cross-compare tumor features in the different EB subtypes and report the most promising therapeutic approaches to counteract or delay EB-SCCs.