MicroRNA-519d inhibits proliferation and induces apoptosis of human hypertrophic scar fibroblasts through targeting Sirtuin 7

Effect of black cloth ointment on hypertrophic scar formation: An investigation using integrated network pharmacology and animal assay

BACKGROUND

Hypertrophic scars (HS) are a common disfiguring condition in daily clinical encounters which brings a lot of anxieties and concerns to patients, but the treatment options of HS are limited. Black cloth ointment (BCO), as a cosmetic ointment applicable to facial scars, has shown promising therapeutic effects for facial scarring. However, the molecular mechanisms underlying its therapeutic effects remain unclear.

MATERIAL AND METHODS

Network pharmacology was first applied to analyze the major active components of BCO and the related signaling pathways. Subsequently, rabbit ear scar model was successfully established to determine the pharmacological effects of BCO and its active component β-elemene on HS. Finally, the molecular mechanism of BCO and β-elemene was analyzed by Western blot.

RESULTS

Through the network pharmacology, it showed that β-elemene was the main active ingredient of BCO, and it could significantly improve the pathological structure of HS and reduce collagen deposition. BCO and β-elemene could increase the expression of ER stress-related markers and promote the increase of apoptotic proteins in the Western blot experiment and induce the apoptosis of myofibroblasts.

CONCLUSIONS

Our findings indicate that the material basis for the scar-improving effects of the BCO is β-elemene, and cellular apoptosis is the key mechanism through which the BCO and β-elemene exert their effects.

Inhibition of phosphatidylinositol 3-kinase catalytic subunit alpha by miR-203a-3p reduces hypertrophic scar formation via phosphatidylinositol 3-kinase/AKT/mTOR signaling pathway

Background

Hypertrophic scar (HS) is a common fibroproliferative skin disease that currently has no truly effective therapy. Given the importance of phosphatidylinositol 3-kinase catalytic subunit alpha (PIK3CA) in hypertrophic scar formation, the development of therapeutic strategies for endogenous inhibitors against PIK3CA is of great interest. Here, we explored the molecular mechanisms underlying the protective effects of miR-203a-3p (PIK3CA inhibitor) against excessive scar.

Methods

Bioinformatic analysis, immunohistochemistry, immunofluorescence, miRNA screening and fluorescence in situ hybridization assays were used to identify the possible pathways and target molecules mediating HS formation. A series of in vitro and in vivo experiments were used to clarify the role of PIK3CA and miR-203a-3p in HS. Mechanistically, transcriptomic sequencing, immunoblotting, dual-luciferase assay and rescue experiments were executed.

Results

Herein, we found that PIK3CA and the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathway were upregulated in scar tissues and positively correlated with fibrosis. We then identified miR-203a-3p as the most suitable endogenous inhibitor of PIK3CA. miR-203a-3p suppressed the proliferation, migration, collagen synthesis and contractility as well as the transdifferentiation of fibroblasts into myofibroblasts in vitro, and improved the morphology and histology of scars in vivo. Mechanistically, miR-203a-3p attenuated fibrosis by inactivating the PI3K/AKT/mTOR pathway by directly targeting PIK3CA.

Conclusions

PIK3CA and the PI3K/AKT/mTOR pathway are actively involved in scar fibrosis and miR-203a-3p might serve as a potential strategy for hypertrophic scar therapy through targeting PIK3CA and inactivating the PI3K/AKT/mTOR pathway.

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.

Intradermal delivery of an angiotensin II receptor blocker using a personalized microneedle patch for treatment of hypertrophic scars

High-quality postoperative rehabilitation is the focus of most patients currently, and hypertrophic scar (HS) greatly reduces the patient's quality of life due to the symptom of severe itching. Traditional HS therapies are associated with limitations, such as poor drug delivery efficiency for topical administration and severe pain for intralesional injection. In this study, we developed a personalized microneedle patch system for minimally invasive and effective treatment of HSs. The microneedle patches were personalized designed and fabricated with 3D printing in order to adapt to individual HS. The optimized microneedle patches were composed of dissolving gelatin and starch and loaded with losartan. Losartan, as a drug class of angiotensin II receptor blockers (ARBs), can effectively inhibit the proliferation and migration of hypertrophic scar fibroblasts (HSFs) and downregulate the gene expression related to scar formation in HSFs. The dissolving microneedle patches exhibited strong mechanical strength, effectively penetrated the stratum corneum of HSs and increased the losartan delivery into HSs upon dissolution of gelatin and starch. Together, the losartan-loaded microneedle patches effectively inhibited the formation of HSs in rabbit ears with reduced scar elevation index (SEI), and decreased fibrosis and collagen deposition in HSs. This personalized microneedle patch system increases the drug delivery efficiency into HSs with minimal invasion, and opens a new window for personalized management and treatment of skin diseases.

Inhibition of ANGPT2 activates autophagy during hypertrophic scar formation via PI3K/AKT/mTOR pathway

BACKGROUND

Hypertrophic scar (HS), a fibroproliferative disorder caused by aberrant wound healing following skin injuries such as burns, lacerations and surgery, is characterized by invasive proliferation of fibroblasts and excessive extracellular matrix (ECM) accumulation. The dysregulation of autophagy is the pathological basis of HS formation. Previously, angiopoietin-2 (ANGPT2) was found to be overexpressed in HS fibroblasts (HSFs) compared with normal skin fibroblasts. However, whether ANGPT2 participates in the process of HS formation and the potential molecular mechanisms are not clear.

OBJECTIVE

This study is intended to figure out the role of ANGPT2 and ANGPT2-mediated autophagy during the development of HS.

METHODS

RT-qPCR was used to detect ANGPT2 expression in HS tissues and HSFs. HSFs were transfected with sh-ANGPT2 to knock down ANGPT2 expression and then treated with MHT1485, the mTOR agonist. The effects of sh-ANGPT2 or MHT1485 on the proliferation, migration, autophagy and ECM accumulation of HSFs were evaluated by CCK-8 assay, Transwell assay and western blotting. The expression of PI3K/Akt/mTOR pathway-related molecules (p-PI3K, p-Akt and p-mTOR) was assessed by western blotting.

RESULTS

ANGPT2 expression was markedly upregulated in HS tissues and HSFs. ANGPT2 knockdown decreased the expression of p-PI3K, p-Akt and p-mTOR. ANGPT2 knockdown activated autophagy and inhibited the proliferation, migration, and ECM accumulation of HSFs. Additionally, the treatment of MHT1485, the mTOR agonist, on ANGPT2-downregulated HSFs, partially reversed the influence of ANGPT2 knockdown on HSFs.

STUDY LIMITATIONS

The study lacks the establishment of more stable in vivo animal models of HS for investigating the effects of ANGPT2 on HS formation in experimental animals.

CONCLUSIONS

ANGPT2 downregulation represses growth, migration, and ECM accumulation of HSFs via autophagy activation by suppressing the PI3K/Akt/mTOR pathway. Our study provides a novel potential therapeutic target for HS.

BMS‐202, a PD‐1/PD‐L1 inhibitor, decelerates the pro‑fibrotic effects of fibroblasts derived from scar tissues via ERK and TGFβ1/Smad signaling pathways

Introduction

Hypertrophic scar (HS), a fibroproliferative disorder of the skin with some tumor‐like properties, is closely related to dysregulated inflammation. PD‐1/PD‐L1 inhibitor is a promising medication for cancer therapy as its potent functions on adaptive immune response; whether it could be a candidate for HS therapy has aroused our interest. This study aimed to explore the effect and the mechanism of BMS‐202, a PD‐1/PD‐L1 inhibitor, in HS.

Methods

Ten HS and adjacent normal skin tissues collected from HS patients were used to detect α‐SMA, collagen I, and PD‐L1 expression by Quantitative reverse transcription‐polymerase chain reaction and western blot (WB) analysis. Fibroblasts derived from HS tissues (HFBs) were exposed to diverse concentrations of BMS‐202, of which proliferation, migration, apoptosis, and collagen synthesis were evaluated by Cell Counting Kit‐8, wound healing, terminal deoxynucleotidyl transferase (TdT) dUTP Nick‐End labeling, and [³H]‑proline incorporation assays, respectively. The effect of BMS‐202 on α‐SMA and collagen I expression, and transforming growth factor beta 1 (TGFβ1)/Smad signaling in HFBs was also determined by WB and enzyme‐linked immunosorbent assay.

Results

The expression level of PD‐L1 was significantly elevated in both HS tissues and HFBs, which was positively correlated with α‐SMA and collagen I expressions. BMS‐202 exerted a significant suppression effect on the cell proliferation, migration, collagen synthesis, and α‐SMA and collagen I expression of HFBs in a concentration‐dependent way; but did not affect apoptosis. Finally, BMS‐202 could reduce the phosphorylation of ERK1/2, Smad2, and Smad3, and the TGFβ1 expression once its concentration reached 2.5 nM.

Conclusion

BMS‐202 effectively suppressed proliferation, migration, and extracellular matrix deposition of HFBs, potentially through the regulation of the ERK and TGFβ1/Smad signaling pathways.

The emerging therapeutic targets for scar management: genetic and epigenetic landscapes

Background

Wound healing is a complex process including hemostasis, inflammation, proliferation, and remodeling during which an orchestrated array of biological and molecular events occurs to promote skin regeneration. Abnormalities in each step of the wound healing process lead to reparative rather than regenerative responses, thereby driving the formation of cutaneous scar. Patients suffering from scars represent serious health problems such as contractures, functional and esthetic concerns as well as painful, thick, and itchy complications, which generally decrease the quality of life and impose high medical costs. Therefore, therapies reducing cutaneous scarring are necessary to improve patients' rehabilitation.

Summary

Current approaches to remove scars, including surgical and nonsurgical methods, are not efficient enough, which is in principle due to our limited knowledge about underlying mechanisms of pathological as well as the physiological wound healing process. Thus, therapeutic interventions focused on basic science including genetic and epigenetic knowledge are recently taken into consideration as promising approaches for scar management since they have the potential to provide targeted therapies and improve the conventional treatments as well as present opportunities for combination therapy. In this review, we highlight the recent advances in skin regenerative medicine through genetic and epigenetic approaches to achieve novel insights for the development of safe, efficient, and reproducible therapies and discuss promising approaches for scar management.

Key Message

Genetic and epigenetic regulatory switches are promising targets for scar management, provided the associated challenges are to be addressed.

Circular RNA HECTD1 knockdown inhibits transforming growth factor-beta/ small mothers against decapentaplegic (TGF-β/Smad) signaling to reduce hypertrophic scar fibrosis

Scars are nearly impossible to avoid after a skin injury, but despite advancements in the treatment modalities, they remain a clinical problem, especially hypertrophic scars (HS). Many studies include the mechanism of formation and inhibition of HS, but it is not fully understood yet. Circular RNA HECTD1 (circHECTD1), for the first time, has been found to have roles in HS physiology. We determined the relative circHECTD1 levels in HS fibrous cells and tissues by RT-qPCR. Afterward, the effect of circHECTD1 knockdown on the proliferation, migration, invasion, fibrosis, and Transforming Growth Factor-beta/small mothers against decapentaplegic (TGF-β/Smad) signaling was studied using CCK-8, wound healing, Transwell, and western blot assays. After the role of circHECTD1 was clarified, its targeted micro RNA (miR) was predicted using the Starbase database, and we constructed a miR-142-3p mimic to study the details of its regulation mechanism. We used the TargetScan database to predict the downstream target high mobility group box 1 (HMGB1) of miR-142-3p, and the luciferase report assay verified the binding, and then its effect was determined by RT-qPCR. circHECTD1 is highly expressed in HS tissues and human skin hypertrophic scar fibroblasts (HSF); its loss of function inhibits cell proliferation, migration, invasion, fibrosis, and TGF-β/Smad signaling. However, miR-142-3p inhibitor reverses the effect of circHECTD1 on all the above-mentioned aspects, including HMGB1 expression. In conclusion, circHECTD1 knockdown interrupts TGF-β/Smad signaling through miR-142-3p/HMGB1 and suppresses scar fibrosis.

Is the future scarless? - Fibroblasts as targets for scarless wound healing: a narrative review

Introduction: Scarless healing is the ideal outcome of wound healing and is exhibited in some species. This narrative review assembles the current understanding of fibroblast heterogenicity along with the latest fibroblast-related targets for scar reduction therapies. Human regenerative wound healing is deemed possible due to the wound regeneration already seen in the early gestation foetus. Methods: This literature narrative review was undertaken by searching PubMed and Web of Science databases and Google Scholar to find articles concerning the fibroblast involvement in wound healing. We evaluated and collated these articles to form a consensus of the current understanding of the field. Discussion: This article describes current understanding of fibroblast heterogenicity and involvement in wound healing, focusing on the role of fibroblasts during physiological scarring. We also present the current most promising targets involving fibroblasts in the reduction of scarring and how we can manipulate the behaviour of fibroblasts to mimic the wound regeneration models in the human foetus. These targets include the pro-fibrotic EN1 positive fibroblast lineage, TGFβ1 inhibition, and genetic therapies utilising miRNAs and siRNAs. Conclusion: No therapies are currently available to eradicate scarring; however, treatment options are available to reduce the appearance of scarring. Further research into the heterogenicity and interactions of fibroblasts in both the foetus and adult is needed, and this may lead to the development of novel treatments against scarring.

MiR-519d-5p modulates the sensitivity of breast cancer to chemotherapy by forming a negative feedback loop with RELA

Background

The chemoresistance of breast cancer (BC) has become the main cause of treatment failure. MicroRNAs (miRNAs) play a critical role in tumorigenesis, development, and chemoresistance, but the underlying mechanism of miR-519d in BC development and chemotherapy sensitivity remains to be elucidated.

Methods

The levels of miR-519d-5p in BC samples and cell lines were measured by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Cell viability was monitored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. The in vivo effect of miR-519d-5p on tumor formation and doxorubicin response were investigated in a xenograft study. Bioinformatic analysis, luciferase reporter assay, RT-qPCR, and western blotting were conducted to validate RELA as a target gene of miR-519d-5p. We performed RT-qPCR, western blotting, chromatin immunoprecipitation (ChIP), and DNA pull down to verify miR-519d-5p as a transcriptional target of RELA.

Results

This study found that miR-519d-5p was expressed at lower levels in BC cells and tissues, and overexpression of miR-519d-5p sensitized BC to chemotherapy both in vitro and in vivo. Meanwhile, the expression of RELA was negatively correlated with miR-519d-5p. We then showed that RELA is one of the targets of miR-519d-5p: miR-519d-5p inhibited RELA expression by directly binding to its 3'-unstranslated region (3'-UTR). Conversely, it was verified that miR-519d-5p is one of the targets of transcription factor RELA, and RELA repressed miR-519d-5p by binding to the promoter region of miR-519d-5p, which forms a feedback loop.

Conclusions

Overall, the results provide a novel therapeutic strategy for the combinational use of miR-519d-5p and chemotherapeutic agents to overcome chemo-resistance by forming a negative feedback loop with RELA.

Inhibition of CUB and sushi multiple domains 1 (CSMD1) expression by miRNA-190a-3p enhances hypertrophic scar-derived fibroblast migration in vitro

Background

Hypertrophic scar (HTS) is a fibroproliferative skin disorder characterized by excessive cell proliferation, migration, and extracellular matrix (ECM) deposition. The CUB and Sushi multiple domains 1 (CSMD1) has previously been identified as the key regulatory gene of hypertrophic scar by a large sample GWAS study. However, further research has not yet been conducted to verify this finding in other HTS patients and to determine the underlying mechanism.

Results

In this study, we verified that CSMD1 was downregulated in both HTS tissue and HTS-derived fibroblasts. The knockdown of CSMD1 resulted in enhanced migration and fibronectin1 (FN1) secretion in fibroblasts in vitro. In addition, the upstream and downstream regulatory mechanisms of CSMD1 were also investigated through microRNA (miRNA) databases screening and RNA-sequencing (RNA-seq) respectively. The screening of four common microRNA (miRNA) databases suggested that miR-190a-3p binds to the CSMD1 and may regulate its expression. We confirmed that miR-190a-3p directly targeted the CSMD1–3′-UTR using luciferase reporter assays. Furthermore, the overexpression of miR-190a-3p showed promotion of migratory activity and FN1 secretion in fibroblasts, resembling the effect of CSMD1 knockdown; whereas the knockdown of miR-190a-3p exerted the opposite effect. Finally, transcriptomic analysis showed activation of Janus kinase-signal transducer and activator of transcription (JAK/STAT) signaling pathway in the CSMD1 knockdown fibroblasts.

Conclusions

This study has validated the conclusions of the previous GWAS study conducted in Chinese population. In vitro experiments have provided further evidence on the function of CSMD1 in the development of HTS, and have also revealed the underlying upstream and downstream regulating mechanisms. Additionally, the JAK/STAT signaling pathway identified using RNA-seq might provide a potential treatment approach, especially for HTS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07920-8.

p75NTR silencing inhibits proliferation, migration, and extracellular matrix deposition of hypertrophic scar fibroblasts by activating autophagy through inhibiting the PI3K/Akt/mTOR pathway

Hypertrophic scar (HS) results from abnormal wound healing, accompanied by excessive hypercellularity, migration, and extracellular matrix (ECM) deposition. Autophagy dysregulation plays crucial roles during HS formation. The overexpressed p75 neurotrophin receptor (p75NTR) in injured skin tissue after wound healing becomes a factor aggravating scar. This study was designed to investigate the role of p75NTR and p75NTR-mediated autophagy in the process of HS. The results revealed that p75NTR expression was significantly upregulated while that of autophagy proteins was downregulated in cicatrix at 3 and 6 months after a burn, which was recovered at 12 months. p75NTR silencing inhibited proliferation, migration, and ECM deposition of hypertrophic scar fibroblasts (HSF), whereas p75NTR overexpression presented the opposite results. Silencing of p75NTR reduced the expression of PI3K/Akt/mTOR signaling molecules while enhancing that of autophagy proteins. Importantly, PI3K agonist (IGF-1) intervention notably decreased the levels of LC3B II/I and Beclin-1 and restored the inhibitory effects of p75NTR silencing on proliferation, migration, and ECM deposition of HSF. Concurrently, autophagy inhibitor 3-methyladenine (3-MA) treatment exhibited the same variation trends with IGF-1. Taken together, these findings demonstrated that p75NTR silencing inhibits proliferation, migration, and ECM deposition of HSF by activating autophagy by inhibiting the PI3K/Akt/mTOR pathway.

MicroRNA-497-5p downregulation inhibits cell viability, reduces extracellular matrix deposition and induces apoptosis in human hyperplastic scar fibroblasts by regulating Smad7

Hypertrophic scars (HSs) are characterized by excessive extracellular matrix deposition and excessive growth of dense fibrous tissues. MicroRNAs (miRNAs/miRs) serve key roles in HS formation. The present study investigated the expression, role and mechanism underlying the effects of miR-497-5p in HS formation. miR-497-5p expression was detected via reverse transcription-quantitative PCR. The association between miR-497-5p and Smad7 was analyzed using TargetScan and luciferase reporter assays. Protein expression levels of extracellular matrix markers were measured via western blotting. Cell viability and apoptosis were determined using the Cell Counting Kit-8 assay and flow cytometry, respectively. The results suggested that miR-497-5p expression was upregulated in HS tissues and human HS fibroblasts (hHSFs) compared with healthy control skin tissues and CCC-ESF-1 cells, respectively. Smad7 was directly targeted by miR-497-5p, and was downregulated in HS tissues and hHSFs compared with healthy control skin tissues and CCC-ESF-1 cells, respectively. Moreover, Smad7 upregulation significantly inhibited cell viability, decreased extracellular matrix deposition and induced apoptosis in hHSFs compared with the control-plasmid group. Moreover, the results indicated that, compared with the inhibitor control group, miR-497-5p inhibitor inhibited cell viability, decreased extracellular matrix deposition and induced apoptosis in hHSFs, which were significantly reversed by Smad7 knockdown. In conclusion, the results indicated that miR-497-5p downregulation repressed HS formation by inhibiting extracellular matrix deposition and hHSF proliferation at least partly by targeting Smad7.

ABT-263 Reduces Hypertrophic Scars by Targeting Apoptosis of Myofibroblasts

Background: Inhibiting proliferation and inducing apoptosis of myofibroblasts is becoming one of the promising and effective ways to treat hypertrophic scar. ABT-263, as an orally bioavailable BCL-2 family inhibitor, has showed great antitumor characteristics by targeting tumor cell apoptosis. The objective of this study was to explore whether ABT-263 could target apoptosis of overactivated myofibroblasts in hypertrophic scar. Methods: In vivo, we used ABT-263 to treat scars in a rabbit ear scar model. Photographs and ultrasound examination were taken weekly, and scars were harvested on day 42 for further Masson trichrome staining. In vitro, the expression levels of BCL-2 family members, including prosurvival proteins, activators, and effectors, were detected systematically in hypertrophic scar tissues and adjacent normal skin tissues, as well as in human hypertrophic scar fibroblasts (HSFs) and human normal dermal fibroblasts (HFBs). The roles of ABT-263 in apoptosis and proliferation of HSFs and HFBs were determined by annexin V/PI assay, CCK-8 kit, and cell cycle analysis. Mitochondrial membrane potential was evaluated by JC-1 staining and the expression of type I/III collagen and α-SMA was measured by PCR, western blotting, and immunofluorescence staining. Furthermore, immunoprecipitation was performed to explore the potential mechanism. Results: In vivo, ABT-263 could significantly improve the scar appearance and collagen arrangement, decrease scar elevation index (SEI), and induce cell apoptosis. In vitro, the expression levels of BCL-2, BCL-XL, and BIM were significantly higher in scar tissues and HSFs than those in normal skin tissues and HFBs. ABT-263 selectively induced HSFs apoptosis by releasing BIM from binding with prosurvival proteins. Moreover, ABT-263 inhibited HSFs proliferation and reduced the expression of α-SMA and type I/III collagen in a concentration- and time- dependent manner. Conclusion: HSFs showed increased mitochondrial priming with higher level of proapoptotic activator BIM and were primed to death. ABT-263 showed great therapeutic ability in the treatment of hypertrophic scar by targeting HSFs.

MicroRNA-9-5p inhibits proliferation and induces apoptosis of human hypertrophic scar fibroblasts through targeting peroxisome proliferator-activated receptor β

Hypertrophic scar (HS) is a dermal fibro-proliferative disorder result from abnormal wound healing after skin injury. MicroRNA-9-5p (miR-9-5p) has been reported to be upregulated and closely related to collagen proteins in human dermal fibroblasts. However, the correlation and possible mechanism between miR-9-5p and HS require further investigation. The expressions of miR-9-5p in HS tissues and HS fibroblasts were detected by quantitative real-time PCR (RT-qPCR). The expression level of peroxisome proliferator-activated receptor β (PPARβ) was measured by RT-qPCR assay. The protein levels of PPARβ, α-SMA, Vimentin, COL1A, cyclin D1, bcl-2, and bax were detected by western blot assay. The effect of miR-9-5p and PPARβ on HS fibroblasts proliferation and apoptosis were detected by cell counting kit-8 (CCK-8) and flow cytometry assays. The interaction between miR-9-5p and PPARβ was predicted by TargetScan, and then confirmed by dual-luciferase reporter assay. MiR-9-5p expression was downregulated in HS tissues and HS fibroblasts. MiR-9-5p inhibited the levels of extracellular matrix-associated genes (α-SMA, Vimentin, COL1A) in HS fibroblasts. MiR-9-5p repressed proliferation and induced apoptosis of HS fibroblasts. PPARβ is a target gene of miR-9-5p. The silencing of PPARβ expression hindered proliferation and expedited apoptosis of HS fibroblasts. MiR-9-5p suppressed proliferation and promoted apoptosis of HS fibroblasts by targeting PPARβ. In this paper, we firstly disclosed that miR-9-5p hampered extracellular matrix deposition and proliferation, and induced apoptosis by targeting PPARβ in HS fibroblasts. Our findings provided a new role of miR-9-5p/PPARβ in the occurrence and development of HS fibroblasts, promising a new target for HS.

Summary: Our findings provided a new role of miR-9-5p/PPAR in the occurrence and development of HS fibroblasts, promising a new target for HS.

Advances in scarless foetal wound healing and prospects for scar reduction in adults

Healing after mammalian skin injury involves the interaction between numerous cellular constituents and regulatory factors, which together form three overlapping phases: an inflammatory response, a proliferation phase and a remodelling phase. Any slight variation in these three stages can substantially alter the healing process and resultant production of scars. Of particular significance are the mechanisms responsible for the scar‐free phenomenon observed in the foetus. Uncovering such mechanisms would offer great expectations in the treatment of scars and therefore represents an important area of investigation. In this review, we provide a comprehensive summary of studies on injury‐induced skin regeneration within the foetus. The information contained in these studies provides an opportunity for new insights into the treatment of clinical scars based on the cellular and molecular processes involved.

The therapeutic effect of Interleukin-18 on hypertrophic scar through inducing Fas ligand expression

OBJECTIVE

Among downstream interleukin-18 (IL-18) targets, Fas ligand (FasL) in particular, has been strongly implicated in many conditions. Our study aims to explore the role of IL-18 in hypertrophic scar through enhancing FasL expression.

METHODS

IL-18 expression in hypertrophic scar tissues and normal tissues were explored by immunohistochemistry, qRT-PCR and Western blotting, and the expression of IL-18 in normal skin fibroblasts and hypertrophic scar fibroblasts by immunofluorescence. Hypertrophic scar fibroblasts treated with recombinant human IL-18 (rhIL-18) were assessed with MTT, Annexin V-FITC/PI, qRT-PCR, ELISA and western blotting. In the hypertrophic scar of rabbit ears, rhIL-18 was injected to determine histological changes with HE and Masson staining. Additionally, the scars were rated based on contour and overall severity using a visual analog scale scores (VAS).

RESULTS

IL-18 was decreased in hypertrophic scar tissues and fibroblasts compared to normal skin tissues and fibroblasts, respectively. Decreased proliferation and increased apoptosis of hypertrophic scar fibroblasts were found after rhIL-18 treatment with enhanced expression of FasL, sFasL FADD, Caspase-8, Caspase-9 and Caspase-3 in a dose-dependent manner. The VAS and thickness of scars in rabbit ears was decreased as time went on after rhIL-18 treatment, with decreases in scar elevation index (SEI) and the increases in FasL expression.

CONCLUSION

IL-18 curbs proliferation and promotes apoptosis of hypertrophic scar fibroblasts by enhancing FasL expression. IL-18is a potential target for treatment of hypertrophic scar.

Inhibition of sphingosine kinase 2 attenuates hypertrophic scar formation via upregulation of Smad7 in human hypertrophic scar fibroblasts

The aims of the present study were to investigate the role of sphingosine kinase 2 (Sphk2) in hypertrophic scar (HS) formation and its underlying mechanisms. The expression levels of Sphk2 and Smad7 in HS tissues and healthy skin tissues of patients undergoing plastic surgery were determined using immunohistochemical staining. Subsequently, the expression levels of Sphk2 and collagen I in human embryonic skin fibroblasts (control) and human HS fibroblasts (HSF) were detected using western blot analysis and immunofluorescence assay, respectively. Following Sphk2 silencing, Smad7 overexpression or both Sphk2 and Smad7 silencing, HSF proliferative ability was assessed using Cell Counting Kit‑8 assay and proliferation‑associated proteins were evaluated using western blot analysis. In addition, the level of apoptosis in HSF was assessed using flow cytometry and expression levels of apoptotic‑associated proteins were determined using western blotting. Furthermore, the expression levels of collagen I and proteins in the TGF‑β1/Smad signaling pathway were detected using western blot analysis. The results indicated that the expression of Sphk2 was significantly increased, while Smad7 expression was decreased in HS tissue. Moreover, the upregulation of Sphk2 and collagen I expression levels was identified in HSF. The present results also indicated that Sphk2 silencing or Smad7 overexpression inhibited proliferation, but promoted apoptosis of HSF, coupled with changes in the expression levels of proliferation‑associated proteins, with an increase in p21 and a decrease in cyclin D1 expression levels, and apoptosis‑associated proteins, with an increase in Bax and cleaved caspase‑3, and a decrease in Bcl‑2, which were reversed following transfection with both Sphk2 and Smad7 using small interfering RNA in HSF. In addition, the expression levels of transforming growth factor‑β1, phosphorylated (p)‑Smad2, p‑Smad3 and collagen I were reduced following Sphk2 silencing or Smad7 overexpression, which were abolished by silencing both Sphk2 and Smad7. Collectively, the present results indicated that inhibition of Sphk2 attenuated HS formation via upregulation of Smad7 expression, thus Sphk2 may serve as a potential therapeutic target for the treatment of HS.

miR-495 inhibits the growth of fibroblasts in hypertrophic scars

Noncoding RNAs are known to be importantly involved in a variety physiological and pathophysiolgical processes. Their role in the pathogenesis of hypertrophic scars remains unclear, however. After preliminary screening of the microRNA (miRNA) gene expression profiles, we explored the role of miR-495 in the development of hypertrophic scar by comparing expression of miR-495 and focal adhesion kinase (FAK) between hypertrophic scar and normal skin tissue. We also used 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide and annexin V-fluorescein isothiocyanate/propidium iodide assays to assess the effect of miR-495 on the proliferation and apoptosis in human hypertrophic scar fibroblasts. Western blotting and real-time polymerase chain reaction were used to evaluate expression of miR-495, FAK, and related proteins in the FAK pathway. Our findings show that miR-495 inhibits FAK and its downstream mediators in vitro and vivo, and suggest that miR-495 may be a useful therapeutic target for the treatment of hypertrophic scar.

Cuprous oxide nanoparticles reduces hypertrophic scarring by inducing fibroblast apoptosis

BACKGROUND

Less apoptosis and excessive growth of fibroblasts contribute to the progression of hypertrophic scar formation. Cuprous oxide nanoparticles (CONPs) could have not only inhibited tumor by inducing apoptosis and inhibiting proliferation of tumor cells, but also promoted wound healing. The objective of this study was to further explore the therapeutic effects of CONPs on hypertrophic scar formation in vivo and in vitro.

METHODS

In vivo, a rabbit ear scar model was established on New Zealand albino rabbits. Six full-thickness and circular wounds (10 mm diameter) were made to each ear. Following complete re-epithelization observed on postoperative day 14, an intralesional injection of CONPs or 5% glucose solution was conducted to the wounds. The photo and ultrasonography of each wound were taken every week and scars were harvested on day 35 for further histomorphometric analysis. In vitro, the role of CONPs in human hypertrophic scar fibroblasts (HSFs) apoptosis and proliferation were evaluated by Tunnel assay, Annexin V/PI staining, cell cycle analysis, and EdU proliferation assay. The endocytosis of CONPs by fibroblasts were detected through transmission electron microscopy (TEM) and the mitochondrial membrane potential and ROS production were also detected.

RESULTS

In vivo, intralesional injections of CONPs could significantly improve the scar appearance and collagen arrangement, and decreased scar elevation index (SEI). In vitro, CONPs could prominently inhibit proliferation and induce apoptosis in HSFs in a concentration-dependent manner. In addition, CONPs could be endocytosed into mitochondria，damage the mitochondrial membrane potential and increase ROS production.

CONCLUSION

CONPs possessed the therapeutic potential in the treatment of hypertrophic scar by inhibiting HSFs proliferation and inducing HSFs apoptosis.

Overexpression of microRNA-519d-3p suppressed the growth of pancreatic cancer cells by inhibiting ribosomal protein S15A-mediated Wnt/β-catenin signaling

Ribosomal protein S15A (RPS15A) has emerged as a novel oncogene of various human cancers. However, whether RPS15A is involved in pancreatic cancer remains unclear. In this study, we aimed to investigate the potential relevance of RPS15A in pancreatic cancer and elucidate the underlying regulatory mechanism. We found that RPS15A expression was significantly up-regulated in pancreatic cancer cell lines. RPS15A knockdown resulted in a decrease of cell proliferation and colony formation, and induced cell cycle arrest in G0/G1 phases of pancreatic cancer cells in vitro. In addition, RPS15A knockdown down-regulated β-catenin expression and blocked the activation of Wnt signaling. Notably, RPS15A was identified as a target gene of microRNA-519d-3p (miR-519d-3p), a tumor suppressive miRNA. Further data showed that miR-519d-3p negatively regulated RPS15A expression in pancreatic cancer cells. Moreover, miR-591d-3p expression was significantly decreased in pancreatic cancer cell lines and tissues and was inversely correlated with RPS15A expression. The overexpression of miR-519d-3p significantly inhibited the proliferation and Wnt/β-catenin signaling in pancreatic cancer cells, mimicking the similar effect of RPS15A knockdown. However, restoration of RPS15A expression partially reversed the antitumor effect of miR-519d-3p. Taken together, our results demonstrate that RPS15A knockdown or RPS15A inhibition by miR-519d-3p suppresses the growth of pancreatic cancer cells associated with the inhibition of Wnt/β-catenin signaling. Our study suggests that the miR-519d-3p/RPS15A/Wnt/β-catenin regulation axis plays an important role in the progression of pancreatic cancer and may serve as potential targets for treatment of pancreatic cancer.