Histamine enhances keratinocyte-mediated resolution of inflammation by promoting wound healing and response to infection

Effects of Histamine and the α-Tocopherol Metabolite α-13'-COOH in an Atopic Dermatitis Full-Thickness Skin Model

Atopic dermatitis is a T-cell mediated inflammatory skin disease with detected elevated levels of histamine in skin or plasma. In this study, the effects of histamine in a T_H2 cytokine environment on human keratinocytes and three-dimensional skin models were investigated. These models were used to explore the anti-inflammatory properties of the α-tocopherol-derived long-chain metabolite α-13'-carboxychromanol (α-13'-COOH). Histamine and T_H2 cytokine-induced proliferation of keratinocytes was studied using a scratch assay. The inflammatory marker interleukin-8 was significantly increased in healthy and T_H2 cytokine-stimulated keratinocytes and skin models after histamine treatment. The incubation of full-thickness skin models with T_H2 cytokines and histamine resulted in morphological changes in the epidermal layer, interpreted as hyperkeratosis. α-13'-COOH significantly decreased interleukin-8 in these disease-associated skin models. Histological staining of filaggrin showed skin-strengthening effects following α-13'-COOH treatment, without changes in mRNA expression. Cytokeratin 10 mRNA expression tended to be increased in response to α-13'-COOH. Anti-allergic properties of α-13'-COOH were studied by pre-incubation of human leukocytes with α-13'-COOH. This resulted in reduced sulfido-leukotriene synthesis. The hyperproliferation effect of histamine in atopic dermatitis skin models may be of further interest to the study of disease-associated morphological changes. Moreover, α-13'-COOH is a promising natural compound for the treatment of inflammatory skin diseases.

The Identification of the Biomarkers of Sheng-Ji Hua-Yu Formula Treated Diabetic Wound Healing Using Modular Pharmacology

Sheng-Ji Hua-Yu (SJHY) formula has been proved to reduce the severity of diabetic wound healing without significant adverse events in our previous clinical trials. However, based on multi-target characteristics, the regulatory network among herbs, ingredients, and hub genes remains to be elucidated. The current study aims to identify the biomarkers of the SJHY formula for the treatment of diabetic wound healing. First, a network of components and targets for the SJHY formula was constructed using network pharmacology. Second, the ClusterONE algorithm was used to build a modular network and identify hub genes along with kernel pathways. Third, we verified the kernel targets by molecular docking to select hub genes. In addition, the biomarkers of the SJHY formula were validated by animal experiments in a diabetic wound healing mice model. The results revealed that the SJHY formula downregulated the mRNA expression of Cxcr4, Oprd1, and Htr2a, while upregulated Adrb2, Drd, Drd4, and Hrh1. Besides, the SJHY formula upregulated the kernel pathways, neuroactive ligand-receptor interaction, and cAMP signaling pathway in the skin tissue homogenate of the diabetic wound healing mice model. In summary, this study identified the potential targets and kernel pathways, providing additional evidence for the clinical application of the SJHY formula for the treatment of diabetic wound healing.

IgE Autoreactivity in Atopic Dermatitis: Paving the Road for Autoimmune Diseases?

Atopic dermatitis (AD) is a common skin disease affecting 20% of the population beginning usually before one year of age. It is associated with the emergence of allergen-specific IgE, but also with autoreactive IgE, whose function remain elusive. This review discusses current knowledge relevant to the mechanisms, which leads to the secretion of autoreactive IgE and to the potential function of these antibodies in AD. Multiple autoantigens have been described to elicit an IgE-dependent response in this context. This IgE autoimmunity starts in infancy and is associated with disease severity. Furthermore, the overall prevalence of autoreactive IgE to multiple auto-antigens is high in AD patients. IgE-antigen complexes can promote a facilitated antigen presentation, a skewing of the adaptive response toward type 2 immunity, and a chronic skin barrier dysfunction and inflammation in patients or AD models. In AD, skin barrier defects and the atopic immune environment facilitate allergen sensitization and the development of other IgE-mediated allergic diseases in a process called the atopic march. AD is also associated epidemiologically with several autoimmune diseases showing autoreactive IgE secretion. Thus, a potential outcome of IgE autoreactivity in AD could be the development of further autoimmune diseases.

Anti-Inflammatory Activity of Miodesin™: Modulation of Inflammatory Markers and Epigenetic Evidence

PURPOSE

To investigate the effects of a combined herbal medicine Miodesin™ on the inflammatory response of key cells involved in the acute and chronic inflammatory processes as well as the possible epigenetic involvement.

METHODS

After the establishment of the IC50 dose, the chondrocyte, keratinocyte, and macrophage cell lines were pretreated for 2 hours with Miodesin™ (200 μg/mL) and stimulated with LPS (1 μg/mL) for 24 hours. The supernatant was used to measure the levels of cytokines (IL-1β, IL-6, IL-8, and TNF-α) and chemokines (CCL2, CCL3, and CCL5), and the cells were used to extract the mRNA for the transcription factor (NF-κβ), inflammatory enzymes (COX-1, COX-2, PLA2, and iNOS), and chemokines (CCL2, CCL3, and CCL5).

RESULTS

Miodesin™ inhibited the release of LPS-induced cytokines (IL-1β, IL-6, IL-8, and TNF-α; p < 0.01) and chemokines (CCL2, CCL3, and CCL5; p < 0.01) and the expression of the transcription factor (NF-κβ; p < 0.01), inflammatory enzymes (COX-1, COX-2, PLA2, iNOS; p < 0.01), and chemokines (CCL2, CCL3, and CCL5; p < 0.01). In addition, the evaluation of epigenetic mechanism revealed that Miodesin™ did not induce changes in DNA methylation, assuring the genetic safeness of the compound in terms of the inflammatory response.

CONCLUSIONS

Miodesin™ presents anti-inflammatory properties, inhibiting hyperactivation of chondrocytes, keratinocytes, and macrophages, involving epigenetics in such effects.

Inflammation-induced IgE promotes epithelial hyperplasia and tumour growth

IgE is the least abundant circulating antibody class but is constitutively present in healthy tissues bound to resident cells via its high-affinity receptor, FcεRI. The physiological role of endogenous IgE antibodies is unclear but it has been suggested that they provide host protection against a variety of noxious environmental substances and parasitic infections at epithelial barrier surfaces. Here we show, in mice, that skin inflammation enhances levels of IgE antibodies that have natural specificities and a repertoire, VDJ rearrangements and CDRH3 characteristics similar to those of IgE antibodies in healthy tissue. IgE-bearing basophils are recruited to inflamed skin via CXCL12 and thymic stromal lymphopoietin (TSLP)/IL-3-dependent upregulation of CXCR4. In the inflamed skin, IgE/FcεRI-signalling in basophils promotes epithelial cell growth and differentiation, partly through histamine engagement of H1R and H4R. Furthermore, this IgE response strongly drives tumour outgrowth of epithelial cells harbouring oncogenic mutation. These findings indicate that natural IgE antibodies support skin barrier defences, but that during chronic tissue inflammation this role may be subverted to promote tumour growth.

5-HT1A Receptor Function Makes Wound Healing a Happier Process

Skin wound healing is a multistage phenomenon that is regulated by cell–cell interplay and various factors. Endogenous serotonin is an important neurotransmitter and cytokine. Its interaction with the serotonin 1A receptor (5-HTR1A) delivers downstream cellular effects. The role of serotonin (5-hydroxytryptamine, 5-HT) and the 5-HT1A receptor has been established in the regeneration of tissues such as the liver and spinal motor neurons, prompting the investigation of the role of 5-HT1A receptor in skin healing. This study assessed the role of 5-HT1A receptor in excisional wound healing by employing an excisional punch biopsy model on 5-Ht1a receptor knockout mice. Post-harvest analysis revealed 5-Ht1a receptor knockout mice showed impaired skin healing, accompanied by a greater number of F4/80 macrophages, which prolongs the inflammatory phase of wound healing. To further unravel this phenomenon, we employed the 5-HT1A receptor agonist [(R)-(+)-8-Hydroxy-DPAT hydrobromide] as a topical cream treatment in an excisional punch biopsy model. The 5-HT1A receptor agonist treated group showed a smaller wound area, scar size, and improved neovascularization, which contributed to improve healing outcomes as compared to the control. Collectively, these findings revealed that serotonin and 5-HT1A receptor play an important role during the healing process. These findings may open new lines of investigation for the potential treatment alternatives to improve skin healing with minimal scarring.

Epigenome-wide DNA methylation regulates cardinal pathological features of psoriasis

Background

Psoriasis is a chronic inflammatory autoimmune skin disorder. Several studies suggested psoriasis to be a complex multifactorial disease, but the exact triggering factor is yet to be determined. Evidences suggest that in addition to genetic factors, epigenetic reprogramming is also involved in psoriasis development. Major histopathological features, like increased proliferation and abnormal differentiation of keratinocytes, and immune cell infiltrations are characteristic marks of psoriatic skin lesions. Following therapy, histopathological features as well as aberrant DNA methylation reversed to normal levels. To understand the role of DNA methylation in regulating these crucial histopathologic features, we investigated the genome-wide DNA methylation profile of psoriasis patients with different histopathological features.

Results

Genome-wide DNA methylation profiling of psoriatic and adjacent normal skin tissues identified several novel differentially methylated regions associated with psoriasis. Differentially methylated CpGs were significantly enriched in several psoriasis susceptibility (PSORS) regions and epigenetically regulated the expression of key pathogenic genes, even with low-CpG promoters. Top differentially methylated genes overlapped with PSORS regions including S100A9, SELENBP1, CARD14, KAZN and PTPN22 showed inverse correlation between methylation and gene expression. We identified differentially methylated genes associated with characteristic histopathological features in psoriasis. Psoriatic skin with Munro’s microabscess, a distinctive feature in psoriasis including parakeratosis and neutrophil accumulation at the stratum corneum, was enriched with differentially methylated genes involved in neutrophil chemotaxis. Rete peg elongation and focal hypergranulosis were also associated with epigenetically regulated genes, supporting the reversible nature of these characteristic features during remission and relapse of the lesions.

Conclusion

Our study, for the first time, indicated the possible involvement of DNA methylation in regulating the cardinal pathophysiological features in psoriasis. Common genes involved in regulation of these pathologies may be used to develop drugs for better clinical management of psoriasis.

Electronic supplementary material

The online version of this article (10.1186/s13148-018-0541-9) contains supplementary material, which is available to authorized users.

The Role of Serotonin during Skin Healing in Post-Thermal Injury

Post-burn trauma significantly raises tissue serotonin concentration at the initial stages of injury, which leads us to investigate its possible role in post burn wound healing. Therefore, we planned this study to examine the role of serotonin in wound healing through in vitro and in vivo models of burn injuries. Results from in vitro analysis revealed that serotonin decreased apoptosis and increased cell survival significantly in human fibroblasts and neonatal keratinocytes. Cellular proliferation also increased significantly in both cell types. Moreover, serotonin stimulation significantly accelerated the cell migration, resulting in narrowing of the scratch zone in human neonatal keratinocytes and fibroblasts cultures. Whereas, fluoxetine (a selective serotonin reuptake inhibitor) and ketanserin (serotonin receptor 2A inhibitor) reversed these effects. Scald burn mice model (20% total body surface area) showed that endogenous serotonin improved wound healing process in control group, whereas fluoxetine and ketanserin treatments (disruptors of endogenous serotonin stimulation), resulted in poor reepithelization, bigger wound size and high alpha smooth muscle actin (α-SMA) count. All of these signs refer a prolonged differentiation state, which ultimately exhibits poor wound healing outcomes. Collectively, data showed that the endogenous serotonin pathway contributes to regulating the skin wound healing process. Hence, the results of this study signify the importance of serotonin as a potential therapeutic candidate for enhancing skin healing in burn patients.

Scar management in burn injuries using drug delivery and molecular signaling: Current treatments and future directions

In recent decades, there have been tremendous improvements in burn care that have allowed patients to survive severe burn injuries that were once fatal. However, a major limitation of burn care currently is the development of hypertrophic scars in approximately 70% of patients. This significantly decreases the quality of life for patients due to the physical and psychosocial symptoms associated with scarring. Current approaches to manage scarring include surgical techniques and non-surgical methods such as laser therapy, steroid injections, and compression therapy. These treatments are limited in their effectiveness and regularly fail to manage symptoms. As a result, the development of novel treatments that aim to improve outcomes and quality of life is imperative. Drug delivery that targets the molecular cascades of wound healing to attenuate or prevent hypertrophic scarring is a promising approach that has therapeutic potential. In this review, we discuss current treatments for scar management after burn injury, and how drug delivery targeting molecular signaling can lead to new therapeutic strategies.

SIRT1, a Class III Histone Deacetylase, Regulates LPS-Induced Inflammation in Human Keratinocytes and Mediates the Anti-Inflammatory Effects of Hinokitiol

Skin inflammation is a response of the immune system to infection and injury. In this study, we report that hinokitiol, a tropolone-related natural compound that exhibits antioxidant, anti-inflammatory, and anticancer properties in various cell types, can modulate the inflammatory responses of primary human keratinocytes challenged with lipopolysaccharide (LPS). Hinokitiol treatment inhibited LPS-mediated up-regulation of proinflammatory factors including tumor necrosis factor alpha, IL-6, and prostaglandin E₂ (PGE₂). NF-κB activation and cell migration induced by LPS were blocked in keratinocytes treated with hinokitiol. Sirt1, a class Ⅲ histone deacetylase, was up-regulated by hinokitiol treatment, and the inhibition of Sirt1 activity using a pharmacological inhibitor or genetic silencing blocked hinokitiol-mediated anti-inflammatory effects. Further, hyperactivation of Sirt1 deacetylase using an adenoviral vector also attenuated LPS-induced inflammatory responses. We thus show that hinokitiol can attenuate LPS-mediated proinflammatory signals via Sirt1 histone deacetylase activation in primary human keratinocytes and suggest that hinokitiol may be a potential therapeutic agent in skin inflammatory diseases like psoriasis.