SHH induces macrophage oxidative phosphorylation and efferocytosis to promote scar formation.

Excessive scar formation such as hypertrophic scars and keloids, resulting from trauma or surgical procedures, present a widespread concern for causing disfigurement, discomfort, and functional limitations. Macrophages play pivotal roles in maintaining tissue homeostasis, orchestrating tissue development, repair, and immune responses, and its transition of function and phenotype plays a critical role in regulating the balance between inflammation and tissue regeneration, which is central to cutaneous scar formation. Recent evidence suggests the involvement of Sonic Hedgehog (SHH) in the induction of anti-inflammatory M2-like macrophage phenotypes within tumor microenvironments. In our study, we observed increased SHH expression in human hypertrophic scars, prompting an investigation into its influence on macrophage polarization, efferocytosis, and cutaneous scar formation. Our findings reveal that SHH can enhance oxidative phosphorylation (OXPHOS) in macrophages, augment macrophage efferocytosis, and promote M2 polarization, finally contributing to the progression of cutaneous scar formation. Notably, targeting SHH signaling with vismodegib exhibited promising potential in mitigating scar formation by reversing the effects of enhanced OXPHOS and M2 polarization in macrophages. In conclusion, this study underscores the critical roles of macrophage metabolism, particularly OXPHOS, efferocytosis and SHH signaling in cutaneous scar formation. Understanding these mechanisms provides new avenues for potential interventions and scar prevention strategies.

Asymmetric adhesive SIS-based wound dressings for therapeutically targeting wound repair.

Severe tissue injuries pose a significant risk to human health. Conventional wound dressings fall short in achieving effective tissue regeneration, resulting in suboptimal postoperative healing outcomes. In this study, an asymmetric adhesive wound dressing (marked as SIS/PAA/LAP) was developed, originating from acrylate acid (AA) solution with laponite (LAP) nanoparticles polymerization and photo-crosslinked on the decellularized extracellular matrix small intestinal submucosa (SIS) patch. Extensive studies demonstrated that the SIS/PAA/LAP exhibited higher tissue adhesion strength (~ 33 kPa) and burst strength (~ 22 kPa) compared to conventional wound dressings like Tegaderm and tissue adhesive products. Importantly, it maintained favorable cell viability and demonstrated robust angiogenic capacity. In animal models of full-thickness skin injuries in rats and skin injuries in Bama miniature pigs, the SIS/PAA/LAP could be precisely applied to wound sites. By accelerating the formation of tissue vascularization, it displayed superior tissue repair outcomes. This asymmetrically adhesive SIS-based patch would hold promising applications in the field of wound dressings.

Application of Decellularized Adipose Matrix as a Bioscaffold in Different Tissue Engineering.

With the development of tissue engineering, the application of decellularized adipose matrix as scaffold material in tissue engineering has been intensively explored due to its wide source and excellent potential in tissue regeneration. Decellularized adipose matrix is a promising candidate for adipose tissue regeneration, while modification of decellularized adipose matrix scaffold can also allow it to transcend the limitations of adipose tissue source properties and applied to other tissue engineering fields, including cartilage and bone tissue engineering, neural tissue engineering, and skin tissue engineering. In this review, we summarized the development of the applications of decellularized adipose matrix in different tissue engineering and present future perspectives.Level of Evidence III This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Identification of fatty acid metabolism-related molecular subtype biomarkers and their correlation with immune checkpoints in cutaneous melanoma.

Purpose: Fatty acid metabolism (FAM) affects the immune phenotype in a metabolically dynamic tumor microenvironment (TME), but the use of FAM-related genes (FAMGs) to predict the prognosis and immunotherapy response of cutaneous melanoma (CM) patients has not been investigated. In this study, we aimed to construct FAM molecular subtypes and identify key prognostic biomarkers in CM. Methods: We used a CM dataset in The Cancer Genome Atlas (TCGA) to construct FAM molecular subtypes. We performed Kaplan-Meier (K-M) analysis, gene set enrichment analysis (GSEA), and TME analysis to assess differences in the prognosis and immune phenotype between subtypes. We used weighted gene co-expression network analysis (WGCNA) to identify key biomarkers that regulate tumor metabolism and immunity between the subtypes. We compared overall survival (OS), progression-free survival (PFS), and disease-specific survival (DSS) between CM patients with high or low biomarker expression. We applied univariable and multivariable Cox analyses to verify the independent prognostic value of the FAM biomarkers. We used GSEA and TME analysis to investigate the immune-related regulation mechanism of the FAM subtype biomarker. We evaluated the immune checkpoint inhibition (ICI) response and chemotherapy sensitivity between CM patients with high or low biomarker expression. We performed real-time fluorescent quantitative PCR (qRT-PCR) and semi-quantitative analysis of the immunohistochemical (IHC) data from the Human Protein Atlas to evaluate the mRNA and protein expression levels of the FAM biomarkers in CM. Results: We identified 2 FAM molecular subtypes (cluster 1 and cluster 2). K-M analysis showed that cluster 2 had better OS and PFS than cluster 1 did. GSEA showed that, compared with cluster 1, cluster 2 had significantly upregulated immune response pathways. The TME analysis indicated that immune cell subpopulations and immune functions were highly enriched in cluster 2 as compared with cluster 1. WGCNA identified 6 hub genes (ACSL5, ALOX5AP, CD1D, CD74, IL4I1, and TBXAS1) as FAM biomarkers. CM patients with high expression levels of the six biomarkers had better OS, PFS, and DSS than those with low expression levels of the biomarkers. The Cox regression analyses verified that the 6 FAM biomarkers can be independent prognostic factors for CM patients. The single-gene GSEA showed that the high expression levels of the 6 genes were mainly enriched in T-cell antigen presentation, the PD-1 signaling pathway, and tumor escape. The TME analysis confirmed that the FAM subtype biomarkers were not only related to immune infiltration but also highly correlated with immune checkpoints such as PD-1, PD-L1, and CTLA-4. TIDE scores confirmed that patients with high expression levels of the 6 biomarkers had worse immunotherapy responses. The 6 genes conveyed significant sensitivity to some chemotherapy drugs. qRT-PCR and IHC analyses verified the expression levels of the 6 biomarkers in CM cells. Conclusion: Our FAM subtypes verify that different FAM reprogramming affects the function and phenotype of infiltrating immune cells in the CM TME. The FAM molecular subtype biomarkers can be independent predictors of prognosis and immunotherapy response in CM patients.

Identification of crucial noncoding RNAs and mRNAs in hypertrophic scars via RNA sequencing.

Hypertrophic scarring (HS) is a dermal fibroproliferative disorder characterized by excessive deposition of collagen and other extracellular matrix components. The aim of this study is to explore crucial long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) associated with HS and provide a better understanding of the molecular mechanism of HS. To investigate the lncRNA, circRNA and mRNA expression profiles, we performed RNA sequencing of human HS and normal skin tissues. After the identification of differentially expressed mRNAs (DEmRNAs), lncRNAs (DElncRNAs) and circRNAs (DEcircRNAs), we performed functional enrichment of DEmRNAs. Further on, we constructed DElncRNA/DEcircRNA-DEmRNA coexpression networks and competing endogenous RNA regulatory networks, and performed functional analyses of the DEmRNAs in the constructed networks. In total, 487 DEmRNAs, 92 DElncRNAs and 17 DEcircRNAs were identified. DEmRNAs were significantly enriched in processes such as collagen fibril organization, extracellular matrix-receptor interaction and the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. In addition, we detected 580 DElncRNA-DEmRNA and 505 DEcircRNA-DEmRNA coexpression pairs. The competing endogenous RNA network contained 18 circRNA-microRNA (miRNA) pairs, 18 lncRNA-miRNA pairs and 409 miRNA-mRNA pairs, including 10 circRNAs, 5 lncRNAs, 15 miRNAs and 160 mRNAs. We concluded that MIR503HG/hsa-miR-204-3p/ACAN, MIR503HG/hsa-miR-431-5p/TNFRSF9, MEG3/hsa-miR-6884-5p/ADAMTS14, AC000035.1-ADAMTS14 and hsa_circ_0069865-COMP/ADAM12 interaction pairs may play a central role in HS.

New Progress of Adipose-derived Stem Cells in the Therapy of Hypertrophic Scars.

Burns are a global public health issue of great concern. The formation of scars after burns and physical dysfunction of patients remain major challenges in the treatment of scars. Regenerative medicine based on cell therapy has become a hot topic in this century. Adipose-derived stem cells (ADSCs) play an important role in cellular therapy and have become a promising source of regenerative medicine and wound repair transplantation. However, the anti-scarring mechanism of ADSCs is still unclear yet. With the widespread application of ADSCs in medical, we firmly believe that it will bring great benefits to patients with hypertrophic scars.

Linagliptin inhibits high glucose-induced transdifferentiation of hypertrophic scar-derived fibroblasts to myofibroblasts via IGF/Akt/mTOR signalling pathway.

Hypertrophic scar (HS) is a fibroproliferative disease after serious burns; the underlying mechanism remains unknown. The study was performed to clarify the effect of high glucose (HG) on HS. The expression of Col1, Col3 and α-SMA was upregulated in HS-derived fibroblasts (HSF) exposed to HG (20 and 30 mmol/L), and HG activated the phosphorylated protein expression of IGF/Akt/mTOR signalling pathway in HSF. Dpp4, a marker targeted the treatment of diabetes mellitus, was overexpressed in HG-induced HSF. Linagliptin, a Dpp4 inhibitor, played the antifibrotic role in HSF exposed to HG, the levels of Col1, Col3 and α-SMA were significantly downregulated, and the cell proliferation and migration were also inhibited. Furthermore, linagliptin alleviated the phosphorylated protein expression of IGF/Akt/mTOR signalling pathway. Moreover, the mTOR inhibitor (rapamycin) mimicked the effect of linagliptin on the collagen and α-SMA that means linagliptin may inhibit HG-induced transdifferentiation of HSF to myofibroblasts via IGF/Akt/mTOR signalling pathway.

Inhibition of SIRT1 by microRNA-9, the key point in process of LPS-induced severe inflammation.

Severe inflammation may lead to multiple organs dysfunction syndrome, which has a high mortality. MicroRNA is found participated in this process. In this study we developed a lipopolysaccharide-induced inflammation cell model on macrophages and a lipopolysaccharide-induced inflammation mouse model. It was found that during inflammation, microRNA-9 was increased, accompanied with the up-regulation of pro-inflammatory cytokines and anti-inflammatory cytokines. Down-regulation of microRNA-9 inhibited the up-regulation of inflammatory cytokines, promoted the up-regulation of anti-inflammatory cytokines and induced the remission of organ damage, showing a protective effect in inflammation. Bioinformatics analysis combined with luciferase reporter assay showed that SIRT1 was the target gene of microRNA-9. Transfection of microRNA-9 inhibitor could increase the level of SIRT1 and decrease the activation of NF-κB pathway in macrophages. Myeloid specific sirt1 knockout mice were included and we found that lack of SIRT1 in mice macrophages led to aggravated inflammation, cell apoptosis and organ injury, and eliminated the protective property of microRNA-9 inhibitor. In conclusion, we demonstrated that inhibition of microRNA-9 could alleviate inflammation through the up-regulation of SIRT1 and then suppressed the activation of NF-κB pathway. This is a meaningful explore about the specific mechanism of microRNA-9 in inflammation.

MicroRNA-146a protects against LPS-induced organ damage by inhibiting Notch1 in macrophage.

MicroRNA-146a is a well-studied microRNA participating in immune and inflammatory diseases, but its role in sepsis has not been investigated. Here in our study, we found increased level of microRNA-146a in macrophage stimulated by lipopolysaccharide. In addition, the mRNA level of Notch1 was also increased. Up-regulation of microRNA-146a by miR-146a-mimic alleviated inflammatory responses of macrophage, for the levels of IL-1ß, IL-6 and CCL-2 were decreased, and the activation of NF-κB signaling was inhibited. The histological examination showed that microRNA-146a protected against organ damage in mice with lipopolysaccharide injection, and the level of inflammatory factors, Cr, BUN, AST and ALT in serum were all decreased, reflecting the alleviated inflammation and recovered organ function. Then predicting databases were used and Notch1 was predicted as one of the potential targets of microRNA-146a. Knockout of Notch1 in macrophage showed reduced secretion of inflammatory factors and attenuated activation of NF-κB signaling in response to lipopolysaccharide. Specifically knockout of Notch1 in macrophage protected mice from LPS induced organ damage and dysfunction. Therefore, we prove that miR-146a acts as an inhibitor of inflammation by targeting Notch1 in macrophage, therefore protects mice from organ damage in sepsis.

MicroRNA-138 Aggravates Inflammatory Responses of Macrophages by Targeting SIRT1 and Regulating the NF-κB and AKT Pathways.

BACKGROUND/AIMS: With increased understanding of sepsis, mortality is decreasing. However, there is still a lack of effective therapeutic strategy. The inflammatory response of macrophages is critical during sepsis. METHODS: Macrophages were stimulated with LPS. Western blotting and qRT-PCR were used to detect inflammatory responses. Then, the inhibitor of microRNA-138 was transfected and Western blotting, qRT-PCR, H&E staining and ELISA were used to verify the role of microRNA-138 in inflammation. Then target gene prediction databases were used to predict the potential target of microRNA-138. Both animal and cell models under LPS challenges were established to verify the regulation of SIRT1 and microRNA-138 during inflammation. RESULTS: The present study showed that microRNA-138 was increased in macrophages stimulated with LPS. Additionally, the NF-κB and AKT pathways were both activated. The pre-treatment of microRNA-138 inhibitor decreased inflammatory factors, downregulated the NF-κB pathway, activated the AKT pathway and protected against organ damage in mice challenged with LPS. SIRT1 was demonstrated as a potential target of microRNA-138In macrophages stimulated with LPS, the inhibition effect of microRNA-138 inhibitor on inflammation was lost by SIRT1 siRNA pre-treatment. In the animal model, the protective effect of microRNA-138 antagomir disappeared in SIRT1 knockout mice. CONCLUSION: We demonstrated that miR-138 participated in the inflammatory process by inhibiting SIRT1 and activating the NF-κB pathway.

Wild-type p53-modulated autophagy and autophagic fibroblast apoptosis inhibit hypertrophic scar formation.

Hypertrophic scarring is a serious fibrotic skin disease, and the abnormal activation of hypertrophic scar fibroblasts (HSFs) intensifies its pathogenesis. Our previous studies have demonstrated that the dysregulation of autophagy in HSFs is associated with fibrosis. However, knowledge regarding the regulation of HS fibrosis by p53-modulated autophagy is limited. Here, we investigated the effect of p53-modulated autophagy on HS fibrosis. The overexpression of wtp53 (Adp53) promoted autophagic capacity and inhibited collagen and α-SMA expression in HSFs. In contrast, LC3 (AdLC3) overexpression did not suppress Col 1, Col 3, or α-SMA expression, but LC3 (shLC3) knockdown downregulated collagen expression. Adp53-modulated autophagy altered Bcl-2 and Bcl-xL expression, but AdLC3 affected only Bcl-xL expression. Silencing Bcl-xL suppressed collagen expression, but autophagy was also inhibited. Flow cytometry showed that the silencing of Bcl-2 (sibcl-2), Bcl-xL (sibcl-xL), and Adp53 significantly increased apoptosis in the HSFs. Therefore, wtp53 inhibited fibrosis in the HSFs by modulating autophagic HSF apoptosis; moreover, the inhibition of autophagy by sibcl-xL had antifibrotic effects. In addition, treatment with Adp53, AdLC3, shLC3, sibcl-2, and sibcl-xL reduced scar formation in a rabbit ear scar model. These data confirm that wtp53-modulated autophagy and autophagic HSF apoptosis can serve as potential molecular targets for HS therapy.

A Randomized, Placebo-Controlled, Double-Blind, Prospective Clinical Trial of Botulinum Toxin Type A in Prevention of Hypertrophic Scar Development in Median Sternotomy Wound.

BACKGROUND: Linear hypertrophic scar is a common surgical problem that can be difficult to manage, especially for the median sternotomy scar. Botulinum toxin type A (BTA) is widely used in cosmetic surgery and has been shown to improve scar quality recently. The aim of this study was to evaluate the efficacy of BTA injected in the early postoperative of median sternotomy on preventing scar formation. METHODS: In this prospective randomized controlled trial, 19 consecutive patients who underwent median sternotomy were enrolled. The median sternotomy wound in each patient was divided into the upper half and the lower half. Both halves of the wound were randomized to receive the treatment with either BTA or normal saline. At 6-month follow-up, scars were assessed using the Vancouver Scar Scale, scar widths were measured, and patients were asked to evaluate their overall satisfaction. RESULTS: Seventeen patients with median sternotomy wounds completed the entire study. At 6-month follow-up, the mean Vancouver Scar Scale score for the BTA-treated group was 3.44 ± 1.68 and for the normal saline control group was 6.29 ± 2.39, and there was a statistically significant difference between the two groups (P < 0.05). There were also significant improvements in scar width and patient satisfaction for the BTA-treated halves of the wounds (P < 0.05). CONCLUSIONS: The study demonstrates that early postoperative BTA injection can decrease scar formation and reduce scar width in median sternotomy wounds, and the overall appearance is more satisfactory. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Klf4 Alleviates Lipopolysaccharide-Induced Inflammation by Inducing Expression of MCP-1 Induced Protein 1 to Deubiquitinate TRAF6.

BACKGROUND/AIMS: Inflammation is an essential component of innate immunity against pathogens, but is tightly regulated, such as by Krüppel-like factor 4 (Klf4), to prevent injury. Klf4 also regulates macrophage polarization, although the mechanisms underlying both functions are poorly understood. The aim of this study was to investigate whether and how Klf4 prevents unregulated inflammation. METHODS: The bone marrow-derived macrophages and RAW264.7 cell line were used. Quantitative real-time PCR was used to determine inflammatory cytokines (IL-1ß, TNF-α, IL-6 and MCP-1), Klf4 and MCPIP1 transcript levels. Extraction of nuclear and cytoplasmic proteins and Immunoblotting were used to determine Klf4, MCPIP1, relative kinases from NF-κB pathway and K63-linked polyubiquitins expression in nucleus and cytoplasm separately. Dual luciferase reporter assay was used to analyze whether Klf4 mediate MCPIP1 transcription. Immunoprecipitation was used to determine the protein interaction among Klf4, MCPIP1, TRAF6 and K63-linked polyubiquitins. Secretion of IL-1ß and TNF-α into sera in mice was measured by Enzyme-linked immunosorbent assay. RESULTS: We found that exposure to lipopolysaccharides suppresses Klf4 expression, even as it induces release of pro-inflammatory cytokines. Strikingly, Klf4 overexpression significantly lowered cytokine secretion and NF-κB signaling in the cytoplasm following exposure to lipopolysaccharide, even though Klf4 was exclusively nuclear. The cytoplasmic effects are likely mediated by MCP-1 induced protein 1 (MCPIP1), a deubiquitinase and a key modulator of inflammation that accumulates both in the nucleus and cytoplasm in response to Klf4. Indeed, binding between MCPIP1 and K63 polyubiquitins is attenuated in macrophages overexpressing Klf4, suggesting that MCPIP1 is an intermediator induced by Klf4 in the nucleus to remove K63 polyubiquitins from TRAF6 in the cytoplasm, and thereby impede NF-κB and inflammatory signaling. Importantly, Klf4 overexpression in mice alleviated sepsis symptoms following exposure to lipopolysaccharides. CONCLUSION: The data highlight Klf4 as an essential MCPIP1-dependent modulator of innate immunity that protects against excessive and self-destructive inflammation.

Cell-free therapy based on adipose tissue stem cell-derived exosomes promotes wound healing via the PI3K/Akt signaling pathway.

INTRODUCTION: Adipose tissue-derived stem cells (ADSCs) have been shown to enhance wound healing via their paracrine function. Exosomes, as one of the most important paracrine factors, play an essential role in this process. However, the concrete mechanisms that underlie this effect are poorly understood. In this study, we aim to explore the potential roles and molecular mechanisms of exosomes derived from ADSCs in cutaneous wound healing. METHODS: Normal human skin fibroblasts and ADSCs were isolated from patient skin and adipose tissues. ADSCs were characterized by using flow cytometric analysis and adipogenic and osteogenic differentiation assays. Exosomes were purified from human ADSCs by differential ultracentrifugation and identified by electron microscopy, nanoparticle tracking, fluorescence confocal microscopy and western blotting. Fibroblasts were treated with different concentrations of exosomes, and the synthesis of collagen was analyzed by western blotting; the levels of growth factors were analyzed by real-time quantitative PCR (RT-PCR) and ELISA; and the proliferation and migration abilities of fibroblasts were analyzed by real-time cell analysis, CCK-8 assays and scratch assays. A mouse model with a full-thickness incision wound was used to evaluate the effect of ADSC-derived exosomes on wound healing. The level of p-Akt/Akt was analyzed by western blotting. Ly294002, a phosphatidylinositol 3-kinases (PI3K) inhibitor, was used to identify the underlying mechanisms by which ADSC-derived exosomes promote wound healing. RESULTS: ADSC-derived exosomes were taken up by the fibroblasts, which showed significant, dose-dependent increases in cell proliferation and migration compared to the behavior of cells without exosome treatment. More importantly, both the mRNA and protein levels of type I collagen (Col 1), type III collagen (Col 3), MMP1, bFGF, and TGF-ß1 were increased in fibroblasts after stimulation with exosomes. Furthermore, exosomes significantly accelerated wound healing in vivo and increased the level of p-Akt/Akt in vitro. However, Ly294002 alleviated these exosome-induced changes, suggesting that exosomes from ADSCs could promote and optimize collagen deposition in vitro and in vivo and further promote wound healing via the PI3K/Akt signaling pathway. CONCLUSIONS: This study demonstrates that ADSC-derived exosomes can promote fibroblast proliferation and migration and optimize collagen deposition via the PI3K/Akt signaling pathway to further accelerate wound healing. Our results suggest that ADSCs likely facilitate wound healing via the release of exosomes, and the PI3K/Akt pathway may play a role in this process. Our data also suggest that the clinical application of ADSC-derived exosomes may shed new light on the use of cell-free therapy to accelerate full-thickness skin wound healing and attenuate scar formation.

Acetylation-Dependent Regulation of Notch Signaling in Macrophages by SIRT1 Affects Sepsis Development.

SIRT1 is reported to participate in macrophage differentiation and affect sepsis, and Notch signaling is widely reported to influence inflammation and macrophage activation. However, the specific mechanisms through which SIRT1 regulates sepsis and the relationship between SIRT1 and Notch signaling remain poorly elucidated. In this study, we found that SIRT1 levels were decreased in sepsis both in vitro and in vivo and that SIRT1 regulation of Notch signaling affected inflammation. In lipopolysaccharide (LPS)-induced sepsis, the levels of Notch signaling molecules, including Notch1, Notch2, Hes1, and intracellular domain of Notch (NICD), were increased. However, NICD could be deacetylated by SIRT1, and this led to the suppression of Notch signaling. Notably, in macrophages from myeloid-specific RBP-J-/- mice, in which Notch signaling is inhibited, pro-inflammatory cytokines were expressed at lower levels than in macrophages from wild-type littermates and in RBP-J-/- macrophages, and the NF-κB pathway was also inhibited. Accordingly, in the case of RBP-J-/- mice, LPS-induced inflammation and mortality were lower than in wild-type mice. Our results indicate that SIRT1 inhibits Notch signaling through NICD deacetylation and thus ultimately alleviates sepsis.

miR-155 inhibits the formation of hypertrophic scar fibroblasts by targeting HIF-1α via PI3K/AKT pathway.

Hypertrophic scar (HS) is a serious skin fibrotic disease characterized by the excessive proliferation of fibroblasts and often considered as a kind of benign skin tumor. microRNA-155 (miR-155) is usually served as a promising marker in antitumor therapy. In view of the similarities of hypertrophic scar and tumor, it is predicted that miR-155 may be a novel therapeutic target in clinical trials. Here we found the expression levels of miR-155 was gradually down regulated and HIF-1α was upregulated in HS tissue and HS derived fibroblasts (HFs). And cell proliferation was inhibited when miR-155 was overexpressed or HIF-1α was silenced. Moreover, overexpression of miR-155 in HFs could reduce the expression of collagens in vitro and inhibit the collagen fibers arrangement in vivo, whereas miR-155 knockdown gave opposite results. Furthermore, we found that miR-155 directly targeted the HIF-1α, which could also independently inhibit the expression of collagens in vitro and obviously improved the appearance and architecture of the rabbit ear scar in vivo when it was silencing. Finally, we found that PI3K/AKT pathway was enrolled in these processes. Together, our results indicated that miR-155 was a critical regulator in the formation and development of hypertrophic scar and might be a potential molecular target for hypertrophic scar therapy.

IL-17 Promotes Scar Formation by Inducing Macrophage Infiltration.

Trauma or burn injuries that affect the deep dermis often produce a hypertrophic scar, which limits patients' joint movement and generates an aesthetic problem. Inflammation is believed to be one of the main pathogenic mechanisms. We found that IL-17 was increased in scar tissues from patients with hypertrophic scar compared with normal skin. Recombinant mouse IL-17 was subcutaneously injected into mice that underwent full-thickness excision surgery to investigate the role of IL-17 in scar formation. Mice stimulated with IL-17 showed aggravated fibrogenesis, delayed wound healing, and increased inflammation. In addition, macrophage infiltration was also increased. According to the results of the Transwell assay, IL-17 promoted macrophage infiltration through an indirect mechanism. After depleting macrophages with clodronate liposomes, the effect of IL-17 disappeared. Levels of monocyte chemotactic protein (MCP) 1, MCP2, and MCP3 (together referred to as MCPs) were increased by IL-17 stimulation. Bindarit (an inhibitor of MCPs) was used to verify the role of MCPs. In addition, the Ly6C-low macrophages were responsible for wound fibrogenesis in mice. In this study, we detected the increased levels of IL-17 for the first time and revealed that IL-17 induced the infiltration of a specific subtype of macrophages to aggravate fibrosis through an MCP-dependent mechanism. Thus, our results provide a better understanding of scar formation and new strategies for scar prevention.

Acute downregulation of miR-199a attenuates sepsis-induced acute lung injury by targeting SIRT1.

MicroRNA-199a (miR-199a) is a novel gene regulator with an important role in inflammation and lung injury. However, its role in the pathogenesis of sepsis-induced acute respiratory distress syndrome (ARDS) is currently unknown. Our study explored the role of miR-199a in sepsis-induced ARDS and its mechanism of action. First, we found that LPS could upregulate miR-199a in alveolar macrophages. Downregulation of miR-199a inhibited the upregulation of inflammatory cytokines in alveolar macrophages and induced the remission of histopathologic changes, the reduction of proinflammatory cytokines, and the upregulation of apoptosis protein expression in an ARDS lung, showing a protective role for miR-199a. We further identified sirtuin 1 (SIRT1) as a direct target of miR-199a in alveolar macrophages, and the expression of SIRT1 was negatively correlated with the level of miR-199a. The protective role of miR-199a downregulation in LPS-stimulated alveolar macrophages and sepsis-induced ARDS could be attenuated by SIRT1 inhibitor. Taken together, these results indicate that downregulation of miR-199a might protect lung tissue against sepsis-induced ARDS by upregulation of SIRT1 through the suppression of excessive inflammatory responses and the inhibition of cellular apoptosis in lung tissue, suggesting its potential therapeutic effects on sepsis-induced ARDS.

Recent advances in hypertrophic scar.

Hypertrophic scars (HTS) are predominant diseases after burn and trauma, which cause severe physiological and psychological problems. HTS have been researched for decades, and our knowledge about the mechanisms of HTS formation process has been increasing. However, the effects of currently available prevention and treatment strategies are limited. In this review, we summarize currently known mechanisms and recent studies of HTS, including extracellular matrix, matrix metalloproteinases, fibroblasts, myofibroblasts and their contraction ability, keratinocytes, growth factors, inflammatory and immune response, and stem cell treatment, hoping for a better understanding of HTS generation, development and effective translation to treatment strategies.

Prolonged skin grafts survival time by IFN-γ in allogeneic skin transplantation model during acute rejection through IFN-γ/STAT3/IDO pathway in epidermal layer.

Allogeneic skin transplantation is the life-saving therapy for multiple diseases, including extensive burn, large-scale trauma and certain post-surgical complications. However, acute rejection impedes clinical application of allogeneic skin transplantation. Although a lot of novel immunosuppressant drugs have been developed, there is still great need for ideal therapy with less complication and more therapeutic effects. Here, we found interferon gamma (IFN-γ) as an immunomodulatory cytokine prolonged the survival time of allografts from (8.50 ±â€¯1.517) days to (14.83 ±â€¯2.714) days at best. Indoleamine-2, 3-dioxygenase (IDO) has been proposed to play key roles in induction of immune tolerance. Using in vitro tissue culture and primary keratinocytes and fibroblasts, we investigated the regulatory effects of IFN-γ on the IDO expression. IFN-γ upregulated IDO expression through STAT3 phosphorylation and this upregulation was reduced by abolition of STAT3 phosphorylation through a STAT3 phosphorylation inhibitor. Interestingly, IFN-γ induced IDO expression predominately in epidermis rather than dermis. In consistent with these results, IFN-γ significantly triggered IDO expression in keratinocytes but not fibroblasts. Taken together, this suggests that IFN-γ might be a potential immunomodulatory drug in acute rejection and keratinocytes in epidermis may play a main role in immune tolerance after allogeneic skin transplantation.