TLR3 activation induces S100A7 to regulate keratinocyte differentiation after skin injury

Oat β-glucan repairs the epidermal barrier by upregulating the levels of epidermal differentiation, cell-cell junctions and lipids via Dectin-1

BACKGROUND AND PURPOSE

Oat β-glucan could ameliorate epidermal hyperplasia and accelerate epidermal barrier repair. Dectin-1 is one of the receptors of β-glucan and many biological functions of β-glucan are mediated by Dectin-1. Dectin-1 promotes wound healing through regulating the proliferation and migration of skin cells. Thus, this study aimed to investigate the role of oat β-glucan and Dectin-1 in epidermal barrier repair.

EXPERIMENTAL APPROACH

To investigate the role of Dectin-1 in the epidermal barrier, indicators associated with the recovery of a damaged epidermal barrier, including histopathological changes, keratinization, proliferation, apoptosis, differentiation, cell-cell junctions and lipid content were compared between WT and Dectin-1-/- mice. Further, the effect of oat β-glucan on the disruption of the epidermal barrier was also compared between WT and Dectin-1-/- mice.

KEY RESULTS

Dectin-1 deficiency resulted in delayed recovery and marked keratinization, as well as abnormal levels of keratinocyte differentiation, cell-cell junctions and lipid synthesis during the restoration of the epidermal barrier. Oat β-glucan significantly reduces epidermal hyperplasia, promotes epidermal differentiation, increases cell-cell junction expression, promotes lipid synthesis and ultimately accelerates the recovery of damaged epidermal barriers via Dectin-1. Oat β-glucan could promote CaS receptor expression and activate the PPAR-γ signalling pathway via Dectin-1.

CONCLUSION AND IMPLICATIONS

Oat β-glucan promote the recovery of damaged epidermal barriers through promoting epidermal differentiation, increasing the expression of cell-cell junctions and lipid synthesis through Dectin-1. Dectin-1 deficiency delay the recovery of epidermal barriers, which indicated that Dectin-1 may be a potential target in epidermal barrier repair.

GLI Transcriptional Targets S100A7 and KRT16 Show Upregulated Expression Patterns in Epidermis Overlying the Tumor Mass in Melanoma Samples

Although not completely understood, the role of the Hedgehog-GLI (HH-GLI) signaling pathway in melanoma and epithelial skin tumors has been reported before. In this study, we confirmed in various melanoma cell line models that keratin 16 (KRT16) and S100 Calcium-Binding Protein A7 (S100A7) are transcriptional targets of GLI Family Zinc Finger (GLI) proteins. Besides their important role in protecting and maintaining the epidermal barrier, keratins are somehow tightly connected with the S100 family of proteins. We found that stronger expression of KRT16 indeed corresponds to stronger expression of S100A7 in our clinical melanoma samples. We also report a trend regarding staining of GLI1, which corresponds to stronger staining of GLI3, KRT16, and S100A7 proteins. The most interesting of our findings is that all the proteins are detected specifically in the epidermis overlying the tumor, but rarely in the tumor itself. The examined proteins were also not detected in the healthy epidermis at the edges of the sample, suggesting that the staining is specific to the epidermis overlaying the tumor mass. Of all proteins, only S100A7 demonstrated a statistically significant trend regarding tumor staging and staining intensity. Results from our clinical samples prove that immune infiltration is an important feature of melanoma. Pigmentophages and tumor-infiltrating lymphocytes (TIL) demonstrate a significant association with tumor stage, while mononuclear cells are equally present in all stages. For S100A7, we found an association between the number of TILs and staining intensity. Considering these new findings presented in our study, we suggest a more detailed examination of the possible role of the S100A7 protein as a biomarker in melanoma.

Bakuchiol and ethyl (linoleate/oleate) synergistically modulate endocannabinoid tone in keratinocytes and repress inflammatory pathway mRNAs

The endocannabinoid (eCB) system plays an active role in epidermal homeostasis. Phytocannabinoids such as cannabidiol modulate this system but also act through eCB-independent mechanisms. This study evaluated the effects of cannabidiol, bakuchiol (BAK), and ethyl (linoleate/oleate) (ELN) in keratinocytes and reconstituted human epidermis. Molecular docking simulations showed that each compound binds the active site of the eCB carrier FABP5. However, BAK and ethyl linoleate bound this site with the highest affinity when combined 1:1 (w/w), and in vitro assays showed that BAK + ELN most effectively inhibited FABP5 and fatty acid amide hydrolase. In TNF-stimulated keratinocytes, BAK + ELN reversed TNF-induced expression shifts and uniquely downregulated type I IFN genes and PTGS2 (COX2). BAK + ELN also repressed expression of genes linked to keratinocyte differentiation but upregulated those associated with proliferation. Finally, BAK + ELN inhibited cortisol secretion in reconstituted human epidermis skin (not observed with cannabidiol). These results support a model in which BAK and ELN synergistically interact to inhibit eCB degradation, favoring eCB mobilization and inhibition of downstream inflammatory mediators (e.g., TNF, COX-2, type I IFN). A topical combination of these ingredients may thus enhance cutaneous eCB tone or potentiate other modulators, suggesting novel ways to modulate the eCB system for innovative skincare product development.

Effect of a DACC-coated dressing on keratinocytes and fibroblasts in wound healing using an in vitro scratch model

Wound dressings that exert an antimicrobial effect in order to prevent and treat wound infections can be harmful to the wound healing process. Dressings with hydrophobic coatings, however, have been suggested to both reduce the microbial load and promote the healing process. Therefore, the potential effects of a dialkylcarbamoyl chloride (DACC)-coated dressing on fibroblasts and keratinocytes in wound healing were studied using mechanical scratch wounding of confluent cell layers as an in vitro model. Additionally, gene expression analysis by qRT-PCR was used to elucidate the longitudinal effects of the DACC-coated dressing on cell responses, specifically inflammation, growth factor induction and collagen synthesis. DACC promoted cell viability, did not stick to the cell layers, and supported normal wound healing progression in vitro. In contrast, cells became attached to the uncoated reference material, which inhibited scratch closure. Moreover, DACC slightly induced KGF, VEGF, and GM-CSF expression in HaCaT cells and NHDF. Physiological COL1A1 and COL3A1 gene expression by NHDF was observed under DACC treatment with no observable effect on S100A7 and RNASE7 levels in HaCaT cells. Overall, the DACC coating was found to be safe and may positively influence the wound healing outcome. Graphical abstract.

Antimicrobial-wound healing peptides: Dual-function molecules for the treatment of skin injuries

Chronic non-healing wounds caused by microbial infections extend the necessity for hospital care and constitute a public health problem and a great financial burden. Classic therapies include a wide range of approaches, from wound debridement to vascular surgery. Antimicrobial peptides (AMPs) are a preserved trait of the innate immune response among different animal species, with known effects on the immune system and microorganisms. Thus, AMPs may represent promising candidates for the treatment of chronic wounds with dual functionality in two of the main agents that lead to this condition, proliferation of microorganisms and uncontrolled inflammation. Here, our goal is to critically review AMPs with wound healing properties. We strongly believe that these dual-function peptides alone, or in combination with other wound healing strategies, constitute an underexplored field that researchers can take advantage of.

Next Generation Sequencing and Cytogenetic Based Evaluation of Indian Pierre Robin Sequence Families Reveals CNV Regions of Modest Effect and a Novel LOXL3 Mutation

BACKGROUND

Pierre Robin Sequence (PRS) affects approximately 1 per 8500 to 14000 new-borns worldwide. Although the clinical entity is well defined, the pathogenesis of PRS is debated. The present study aims to understand the contribution of genomic imbalances and genetic variants in patients clinically diagnosed of PRS.

METHODOLOGY

A total of 7 independent patients with nonsyndromic PRS thoroughly evaluated by a medical geneticist at a tertiary care hospital, were included in the study. Blood samples were collected from these patients and their family members. Array CGH was performed on all 7 patients and their respective family members for detection of underlying cytogenetic defects. Whole exome sequencing (WES) was performed for 5 families to capture single nucleotide variants or small indels.

RESULTS

Cytogenetic analyses did not detect any previously reported gross chromosomal aberrations for PRS in the patient cohort. However, copy number variations (CNVs) of size <1 Mb were detected in patients which may have implications in PRS. The present study provided evidence for the occurrence of de novo deletions at 7p14.1 locus in PRS patients: further validating the candidate loci susceptibility in oral clefts. WES data identified LOXL3 as candidate gene, carrying novel deleterious variant, which is suggestive of the role of point mutations in the pathogenesis of PRS.

CONCLUSION

The present study offered considerable insight into the contribution of cytogenetic defects and novel point mutation in the etiology of nonsyndromic PRS. Studies comprising large number of cases are required to fully elucidate the genetic mechanisms underlying the PRS phenotype.

Purinergic Signaling and Inflammasome Activation in Psoriasis Pathogenesis

Psoriasis is a chronic inflammatory disease of the skin associated with systemic and joint manifestations and accompanied by comorbidities, such as metabolic syndrome and increased risk of cardiovascular disease. Psoriasis has a strong genetic basis, but exacerbation requires additional signals that are still largely unknown. The clinical manifestations involve the interplay between dendritic and T cells in the dermis to generate a self-sustaining inflammatory loop around the TNFα/IL-23/IL-17 axis that forms the psoriatic plaque. In addition, in recent years, a critical role of keratinocytes in establishing the interplay that leads to psoriatic plaques’ formation has re-emerged. In this review, we analyze the most recent evidence of the role of keratinocytes and danger associates molecular patterns, such as extracellular ATP in the generation of psoriatic skin lesions. Particular attention will be given to purinergic signaling in inflammasome activation and in the initiation of psoriasis. In this phase, keratinocytes’ inflammasome may trigger early inflammatory pathways involving IL-1β production, to elicit the subsequent cascade of events that leads to dendritic and T cell activation. Since psoriasis is likely triggered by skin-damaging events and trauma, we can envisage that intracellular ATP, released by damaged cells, may play a role in triggering the inflammatory response underlying the pathogenesis of the disease by activating the inflammasome. Therefore, purinergic signaling in the skin could represent a new and early step of psoriasis; thus, opening the possibility to target single molecular actors of the purinome to develop new psoriasis treatments.

S100A7 as a potential diagnostic and prognostic biomarker of esophageal squamous cell carcinoma promotes M2 macrophage infiltration and angiogenesis

Dysregulated expression of S100A7 is found in several cancers and plays an important role in tumor progression; however, its carcinogenic role in esophageal squamous carcinoma (ESCC) is still poorly understood. Here, we identified that the levels of S100A7 were remarkably upregulated in 341 tumor tissues (P < .001) and 274 serum samples (P < .001) of ESCC patients compared with normal control. It was an independent prognostic factor (P = .026). Furthermore, a new diagnostic model for ESCC based on serum S100A7, SCC, and crfra21-1 was established with area under curve (AUC) up to 0.863 (95% CI: 0.802-0.925). Mechanically, we found upregulated S100A7 could promote cell migration and proliferation through intracellular binding to JAB1 and paracrine interaction with RAGE receptors and then activates the downstream signaling pathways. In addition, exocrine S100A7 could promote M2 macrophage infiltration and polarization by up-regulating M2 macrophage associated proteins, and tumor angiogenesis by enhancing the activation of p-ErK and p-FAK pathways. Further animal experiments confirmed the role of S100A7 in promoting M2 macrophage infiltration and angiogenesis in ESCC. In conclusion, these findings highlighted the potential diagnostic and prognostic value of S100A7 in patients with ESCC. Meanwhile, our results reveal that S100A7 promotes tumor progression by activating oncogenic pathways and remodeling tumor microenvironment, which paving the way for the progress of S100A7 as a therapeutic target for cancer treatment.

Nicotinamide Riboside Enhances Endothelial Precursor Cell Function to Promote Refractory Wound Healing Through Mediating the Sirt1/AMPK Pathway

Lack of vascularization is directly associated with refractory wound healing in diabetes mellitus (DM). Enrichment of endothelial precursor cells (EPCs) is a promising but challenging approach for the treatment of diabetic wounds. Herein, we investigate the action of nicotinamide riboside (NR) on EPC function for improved healing of diabetic wounds. Db/db mice that were treated with NR-supplemented food (400 mg/kg/d) for 12 weeks exhibited higher wound healing rates and angiogenesis than untreated db/db mice. In agreement with this phenotype, NR supplementation significantly increased the number of blood EPCs and bone marrow (BM)-derived EPCs of db/db mice, as well as the tube formation and adhesion functions of BM-EPCs. Furthermore, NR-supplemented BM-EPCs showed higher expression of sirtuin 1 (Sirt1), phosphorylated adenosine monophosphate–activated protein kinase (p-AMPK), and lower expression of acetylated peroxisome proliferator–activated receptor γ coactivator (PGC-1α) than BM-EPCs isolated from untreated db/db mice. Knockdown of Sirt1 in BM-EPCs significantly abolished the tube formation and adhesion function of NR as well as the expression of p-AMPK and deacetylated PGC-1a. Inhibition of AMPK abolished the NR-regulated EPC function but had no effect on Sirt1 expression, demonstrating that NR enhances EPC function through the Sirt1-AMPK pathway. Overall, this study demonstrates that the oral uptake of NR enhances the EPC function to promote diabetic wound healing, indicating that NR supplementation might be a promising strategy to prevent the progression of diabetic complications.

Antimicrobial peptides: bridging innate and adaptive immunity in the pathogenesis of psoriasis

Antimicrobial peptides (AMPs) are small molecules produced by a myriad of cells and play important roles not only in protecting against infections and sustaining skin barrier homeostasis but also in contributing to immune dysregulation under pathological conditions. Recently, increasing evidence has indicated that AMPs, including cathelicidin (LL-37), human β-defensins, S100 proteins, lipocalin 2, and RNase 7, are highly expressed in psoriatic skin lesions. These peptides broadly regulate immunity by interacting with various immune cells and linking innate and adaptive immune responses during the progression of psoriasis. In this review, we summarize the recent findings regarding AMPs in the pathogenesis of psoriasis with a main focus on their immunomodulatory abilities.

IL-36γ Induced by the TLR3-SLUG-VDR Axis Promotes Wound Healing via REG3A

IL-36 family members are highly expressed in hyperproliferative keratinocytes and play an important role in the pathogenesis of skin diseases such as psoriasis. However, whether and how IL-36 cytokines are induced to promote wound healing remains unknown. Here we showed that skin injury increased the expression of IL-36γ to promote wound healing. Mechanistically, the expression of IL-36γ was induced by RNAs from damaged cells via the activation of toll-like receptor 3 (TLR3) and TIR-domain-containing adapter-inducing IFN-β (TRIF) followed by the induction of a zinc finger protein SLUG to abrogate the inhibitory effect of vitamin D receptor (VDR) on the promoter of IL-36γ gene. IL-36γ acted back on keratinocytes to induce REG3A, which regulated keratinocyte proliferation and differentiation, thus promoting wound re-epithelialization. These observations show that skin injury increases IL-36γ via the activation of TLR3-SLUG-VDR axis and that IL-36γ induces REG3A to promote wound healing. These findings also provide insights into pathways contributing to wound repair.

Platelet-released growth factors induce psoriasin in keratinocytes: Implications for the cutaneous barrier

Millions of patients around the world suffer minor or major extremity amputation due to progressive wound healing complications of chronic or infected wounds, the therapy of which remains a challenge. One emerging therapeutic option for the treatment of these complicated wounds is the local application of an autologous thrombocytes concentrate lysate (e.g. platelet-released growth factors ((PRGF)) or Vivostat PRF^®) that contains a multitude of chemokines, cytokines and growth factors and is therefore supposed to stimulate the complex wound healing process. Although PRGF and Vivostat PRF^® are already used successfully to support healing of chronic, hard-to-heal and infected wounds the underlying molecular mechanisms are not well understood. Psoriasin, also termed S100A7, is a multifunctional antimicrobial protein expressed in keratinocytes and is involved in various processes such as wound-healing, angiogenesis, innate immunity and immune-modulation. In this study, we investigated the influence of PRGF on psoriasin expression in human primary keratinocytes in vitro and the influence of Vivostat PRF^® on psoriasin expression in experimentally generated skin wounds in vivo. PRGF treatment of primary keratinocytes caused a significant concentration- and time-dependent increase of psoriasin gene and protein expression in vitro that were partially mediated by the epidermal growth factor receptor (EGFR) and the interleukin-6 receptor (IL-6R). In accordance with these cell culture data, Vivostat PRF^® induced a significant psoriasin gene and protein expression when applied to artificially generated skin wounds in vivo. The observed psoriasin induction in keratinocytes may contribute to the wound healing-promoting effects of therapeutically used thrombocyte concentrate lysates.

Human S100A7 Induces Mature Interleukin1α Expression by RAGE-p38 MAPK-Calpain1 Pathway in Psoriasis

Psoriatic keratinocytes express exaggerated levels of inflammatory cytokines, and show aberrant hyperproliferation and terminal differentiation in the pathogenesis of psoriasis. The antimicrobial protein hS100A7 (psoriasin) has been found highly expressed in psoriatic skin, but the mechanism and physiological function remain largely unknown. We observed that hS100A7 induces mature interleukin 1α (17kDa) expression in normal human epidermal keratinocytes, which is dependent on RAGE-p38 MAPK and calpain-1 as the inhibitors or knockdown of them completely decreased the expression of mature interleukin1α. Then, we proved mS100a7a15, mature IL-1α and calpain-1 were highly expressed in imquimod-induced psoriasis model and mouse IL-17a-neutralizing antibody treatment attenuated mS100a7a15 expression. At last, PD 151746 (calpain-1 inhibitor) treatment decreased epidermal thickness in imquimod-induced psoriasis model. Taken together, our results suggest that mature IL-1α induced by hS100A7 is via RAGE-p38 MAPK and calpain-1 pathway in keratinocyte and this mechanism may play an important role during psoriasis.