YTHDC1-Modified m6A Methylation of Hsa_circ_0102678 Promotes Keratinocyte Inflammation Induced by Cutibacterium acnes Biofilm through Regulating miR-146a/TRAF6 and IRAK1 Axis

INTRODUCTION

CircRNAs are closely related to many human diseases; however, their role in acne remains unclear. This study aimed to determine the role of hsa_circ_0102678 in regulating inflammation of acne.

METHODS

First, microarray analysis was performed to study the expression of circRNAs in acne. Subsequently, RNase R digestion assay and fluorescence in situ hybridization assay were utilized to confirm the characteristics of hsa_circ_0102678. Finally, qRT-PCR, Western blotting analysis, immunoprecipitation, luciferase reporter assay, circRNA probe pull-down assay, biotin-labeled miRNA pull-down assay, RNA immunoprecipitation assay, and m6A dot blot assay were utilized to reveal the functional roles of hsa_circ_0102678 on inflammation induced by C. acnes biofilm in human primary keratinocytes.

RESULTS

Our investigations showed that the expression of hsa_circ_0102678 was significantly decreased in acne tissues, and hsa_circ_0102678 was a type of circRNAs, which was mainly localized in the cytoplasm of primary human keratinocytes. Moreover, hsa_circ_0102678 remarkably affected the expression of IL-8, IL-6, and TNF-α, which induced by C. acnes biofilm. Importantly, mechanistic studies indicated that the YTHDC1 could bind directly to hsa_circ_0102678 and promote the export of N6-methyladenosine-modified hsa_circ_0102678 to the cytoplasm. Besides, hsa_circ_0102678 could bind to miR-146a and sponge miR-146a to promote the expression of IRAK1 and TRAF6.

CONCLUSION

Our findings revealed a previously unknown process by which hsa_circ_0102678 promoted keratinocyte inflammation induced by C. acnes biofilm via regulating miR-146a/TRAF6 and IRAK1 axis.

Role of ADAM10 and ADAM17 in the Regulation of Keratinocyte Adhesion in Pemphigus Vulgaris

The severe autoimmune blistering disease Pemphigus vulgaris (PV) is mainly caused by autoantibodies (IgG) against desmoglein (Dsg) 3 and Dsg1. The mechanisms leading to the development of blisters are not fully understood, but intracellular signaling seems to play an important role. Sheddases ADAM10 and ADAM17 are involved in the turnover of the desmosomal cadherin Dsg2 and ADAM10 has been shown to contribute to acantholysis in a murine pemphigus model. In the present study, we further examined the role of ADAM10 and ADAM17 both in keratinocyte adhesion and in the pathogenesis of PV. First, we found that inhibition of ADAM10 enhanced adhesion of primary human keratinocytes but not of immortalized keratinocytes. In dissociation assays, inhibition of ADAM10 shifted keratinocyte adhesion towards a hyperadhesive state. However, ADAM inhibition did neither modulate protein levels of Dsg1 and Dsg3 nor activation of EGFR at Y1068 and Y845. In primary human keratinocytes, inhibition of ADAM10, but not ADAM17, reduced loss of cell adhesion and fragmentation of Dsg1 and Dsg3 immunostaining in response to a PV1-IgG from a mucocutaneous PV patient. Similarly, inhibition of ADAM10 in dissociation assay decreased fragmentation of primary keratinocytes induced by a monoclonal antibody against Dsg3 and by PV-IgG from two other patients both suffering from mucosal PV. However, such protective effect was not observed in both cultured cells and ex vivo disease models, when another mucocutaneous PV4-IgG containing more Dsg1 autoantibodies was used. Taken together, ADAM10 modulates both hyperadhesion and PV-IgG-induced loss of cell adhesion dependent on the autoantibody profile.

Hspa8 and ICAM-1 as damage-induced mediators of γδ T cell activation

Tissue-resident γδ T cells form the first line of defense at barrier surfaces where they survey host tissue for signs of stress or damage. Following recognition of injury, γδ T cells play a crucial role in the wound-healing response through the production of growth factors and cytokines that promote proliferation in surrounding epithelial cells. To initiate this response, γδ T cells require interactions with a variety of epithelial-expressed costimulatory molecules in addition to primary signaling through their TCR. In the epidermis these signals include the coxsackie and adenovirus receptor (CAR), histocompatibility antigen 60c (H60c), and plexin B2, which interact with γδ T cell-expressed junctional adhesion molecule-like protein (JAML), NKG2D, and CD100, respectively. Here we identify heat shock protein family A member 8 (Hspa8) and ICAM-1 as two additional keratinocyte-expressed costimulatory molecules for epidermal resident γδ T cells (termed DETC). These molecules were rapidly up-regulated in the epidermis following wounding in both mouse and human tissue. Both Hspa8 and ICAM-1 had a costimulatory effect on DETC, inducing proliferation, CD25 up-regulation, and IL-2 production. We also provide evidence that DETC can be activated through the potential ICAM-1 and Hspa8 receptors LFA-1 and CD316. Finally, knockdown of Hspa8 in keratinocytes reduced their ability to activate DETC in culture and ICAM-1-/- mice exhibited impaired rates of healing in skin-organ culture suggesting a role for these proteins in the DETC-mediated damage response. Together with previous work on CAR, H60c, and plexin B2, these results add to a picture of a complex keratinocyte wound signature that is required for efficient DETC activation.

A single dose of Ultraviolet-A induces proteome remodeling and senescence in primary human keratinocytes

Epidermal photoaging contributes to skin fragility over time and it is a risk factor for skin cancer. Photoaging has been associated for a long time with exposure to Ultraviolet-A (UVA) light, the predominant component of the solar ultraviolet radiation. While the cellular mechanisms underlying UVA-induced photoaging in the dermis have been well characterized, UVA's action on the epidermis remains elusive. Here, proteomic analysis was conducted to derive the cellular responses induced by an environmentally relevant dose of UVA in primary human keratinocytes. We also investigated the effects of UVA on non-transformed immortalized keratinocytes (HaCaT cells), bearing potentially oncogenic mutations. We showed that UVA induces proteome remodeling and senescence in primary keratinocytes, eliciting potent antioxidant and pro-inflammatory responses. Additionally, we showed that UVA modulates the secretory phenotype of these cells to the extent of inducing paracrine oxidative stress and immune system activation in pre-malignant keratinocytes. These observations offer insights into the cellular mechanisms by which UVA drives photoaging in the skin.

Cutaneous Neuroimmune Interactions of TSLP and TRPV4 Play Pivotal Roles in Dry Skin-Induced Pruritus

Dry skin is a symptom of skin barrier dysfunction that evokes pruritus; however, the cutaneous neuroimmune interactions underlying dry skin-induced pruritus remain unclear. Therefore, we aimed to elucidate the mechanisms underlying dry skin-induced pruritus. To this end, an acetone/ethanol/water (AEW)-induced mouse model of dry skin was used in this study. We observed that the production of thymic stromal lymphopoietin (TSLP) significantly increased in the keratinocytes of AEW mice. Importantly, treatment with an antagonist of transient receptor potential cation channel subfamily V member 4 (TRPV4), HC067047, ameliorated dry skin conditions in AEW mice. The symptoms of dry skin were significantly reduced in Trpv4 knockout (KO) mice following treatment with AEW. The increase in the intracellular calcium levels by TSLP in the dorsal root ganglia (DRG) of Trpv4 KO mice was also significantly attenuated. The spontaneous scratching bouts were significantly decreased in both the HC067047-treated and Trpv4 KO AEW mice. Importantly, the TSLP-dependent release of tryptase from the mast cells was significantly reduced in both the HC067047-treated mice and Trpv4 KO AEW mice. Notably, inhibition of the TSLP-induced signaling pathway in DRG selectively reduced the spontaneous scratching bouts in AEW mice. Overall, the results demonstrated that the cutaneous neuroimmune interactions of TSLP and TRPV4 play pivotal roles in dry skin-induced pruritus.

Comparison of Two Diagnostic Assays for Anti-Laminin 332 Mucous Membrane Pemphigoid

Anti-laminin 332 mucous membrane pemphigoid (MMP) is an autoimmune blistering disease characterized by predominant mucosal lesions and autoantibodies against laminin 332. The exact diagnosis of anti-laminin 332 MMP is important since nearly 30% of patients develop solid cancers. This study compared two independently developed diagnostic indirect immunofluorescence (IF) tests based on recombinant laminin 332 expressed in HEK239 cells (biochip mosaic assay) and the migration trails of cultured keratinocytes rich in laminin 332 (footprint assay). The sera of 54 anti-laminin 332 MMP, 35 non-anti-laminin 332 MMP, and 30 pemphigus vulgaris patients as well as 20 healthy blood donors were analyzed blindly and independently. Fifty-two of 54 and 54/54 anti-laminin 332 MMP sera were positive in the biochip mosaic and the footprint assay, respectively. In the 35 non-anti-laminin 332 MMP sera, 3 were positive in both tests and 4 others showed weak reactivity in the footprint assay. In conclusion, both assays are easy to perform, highly sensitive, and specific, which will further facilitate the diagnosis of anti-laminin 332 MMP.

Subunit-Specific Reactivity of Autoantibodies Against Laminin-332 Reveals Direct Inflammatory Mechanisms on Keratinocytes

Laminin-332 pemphigoid is a rare and severe autoimmune blistering disease, caused by IgG autoantibodies targeting laminin-332 in the dermal-epidermal basement zone. Laminin-332 pemphigoid is characterized by variable inflammatory infiltrate and the predominance of non-complement-fixing antibodies. Given these findings, we hypothesized that IgG autoantibodies to laminin-332 directly resulted in keratinocyte expression of inflammatory factors. We performed RNA-seq on primary human keratinocytes treated with IgG from patients with laminin-332 pemphigoid. Genes for numerous cytokines and chemokines were upregulated, including CSF2, CSF3, CXCL1, CXCL5, CXCL3, CXCL8, CXCL10, CXCL1, IL6, IL7, IL15, IL23, IL32, IL37, TGFB2 as well as metalloproteases. Considering the pro-inflammatory and proteolytic effect of autoantibodies from patients with laminin-332 pemphigoid identified in our initial experiment, we next questioned whether the reactivity against specific laminin subunits dictates the inflammatory and proteolytic keratinocyte response. Then, we treated keratinocytes with IgG from a separate cohort of patients with reactivity against individual subunits of laminin-332. We identified upregulation of IL-1α, IL-6, IL-8, CXCL1, MMP9, TSLP, and GM-CSF at the protein level, most notably in keratinocytes treated with IgG from laminin β3-reactive patients. We for the first time demonstrated a pro-inflammatory response, similar to that described in keratinocytes treated with IgG autoantibodies from patients with bullous pemphigoid, providing novel insight into the pathogenesis of laminin-332 pemphigoid and laminin-332 biology.

Topical application of celastrol alleviates atopic dermatitis symptoms mediated through the regulation of thymic stromal lymphopoietin and group 2 innate lymphoid cells

Atopic dermatitis is a chronic inflammatory skin disease, of which incidence is closely related to exposure to environmental pollutants and allergens. Thymic stromal lymphopoietin (TSLP) plays an important role in the early stages of atopic dermatitis development by inducing Th2 immune responses. In addition, TSLP regulates activation of group 2 innate lymphoid cells (ILC2), promoting the pathogenesis of atopic dermatitis. The aim of this study was to investigate whether celastrol alleviated atopic dermatitis symptoms by regulating TSLP expression and ILC2 stimulation. Celastrol suppressed TSLP production in mouse keratinocyte cells by inhibiting NF-ĸB activation. Topical application of celastrol significantly improved atopic dermatitis symptoms induced by house dust mite (HDM) in NC/Nga mice as determined by dermatitis score and histological assessment. Celastrol decreased the levels of TSLP in atopic dermatitis skin lesions of HDM-stimulated NC/Nga mice. Celastrol reduced levels of Th2 cytokines including IL-4, IL-5, and IL-13 in atopic dermatitis skin lesions of NC/Nga mice. Further, celastrol significantly reduced ILC2 population in atopic dermatitis skin lesions of NC/Nga mice. These results indicate that topical application of celastrol improved atopic dermatitis symptoms by lowering TSLP levels and concomitant immune responses. Data demonstrated that reduced TSLP levels and associated lower number of ILC2 cells alleviate atopic dermatitis symptoms induced by house dust mite.

DNA hypomethylation leads to cGAS-induced autoinflammation in the epidermis

DNA methylation is a fundamental epigenetic modification, important across biological processes. The maintenance methyltransferase DNMT1 is essential for lineage differentiation during development, but its functions in tissue homeostasis are incompletely understood. We show that epidermis-specific DNMT1 deletion severely disrupts epidermal structure and homeostasis, initiating a massive innate immune response and infiltration of immune cells. Mechanistically, DNA hypomethylation in keratinocytes triggered transposon derepression, mitotic defects, and formation of micronuclei. DNA release into the cytosol of DNMT1-deficient keratinocytes activated signaling through cGAS and STING, thus triggering inflammation. Our findings show that disruption of a key epigenetic mark directly impacts immune and tissue homeostasis, and potentially impacts our understanding of autoinflammatory diseases and cancer immunotherapy.

BP180/Collagen XVII: A Molecular View

BP180 is a type II collagenous transmembrane protein and is best known as the major autoantigen in the blistering skin disease bullous pemphigoid (BP). The BP180 trimer is a central component in type I hemidesmosomes (HD), which cause the adhesion between epidermal keratinocytes and the basal lamina, but BP180 is also expressed in several non-HD locations, where its functions are poorly characterized. The immunological roles of intact and proteolytically processed BP180, relevant in BP, have been subject to intensive research, but novel functions in cell proliferation, differentiation, and aging have also recently been described. To better understand the multiple physiological functions of BP180, the focus should return to the protein itself. Here, we comprehensively review the properties of the BP180 molecule, present new data on the biochemical features of its intracellular domain, and discuss their significance with regard to BP180 folding and protein-protein interactions.

Essential Role of STAT3 Signaling in Hair Follicle Homeostasis

Dominant-negative mutations associated with signal transducer and activator of transcription 3 (STAT3) signaling, which controls epithelial proliferation in various tissues, lead to atopic dermatitis in hyper IgE syndrome. This dermatitis is thought to be attributed to defects in STAT3 signaling in type 17 helper T cell　specification. However, the role of STAT3 signaling in skin epithelial cells remains unclear. We found that STAT3 signaling in keratinocytes is required to maintain skin homeostasis by negatively controlling the expression of hair follicle-specific keratin genes. These expression patterns correlated with the onset of dermatitis, which was observed in specific pathogen-free conditions but not in germ-free conditions, suggesting the involvement of Toll-like receptor-mediated inflammatory responses. Thus, our study suggests that STAT3-dependent gene expression in keratinocytes plays a critical role in maintaining the homeostasis of skin, which is constantly exposed to microorganisms.

Pathogenic Mechanism of Der p 38 as a Novel Allergen Homologous to RipA and RipB Proteins in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic relapsing pruritic disease encompassing skin inflammation and barrier dysfunction. House dust mites are key allergens that augment the development of atopic dermatitis. We aimed to investigate the pathogenic mechanism of AD due to Der p 38, recently identified by us. The frequency of IgE reactivity to Der p 38 in AD subjects was 52.6% (10/19) in the skin prick test and 57.9% (11/19) in the dot blot assay. In human keratinocyte HaCaT cells, Der p 38 triggered the impairment of filaggrin expression and induced pro-inflammatory cytokines such as IL-6, IL-8 and MCP-1 through TLR4, PI3K, AKT, c-Jun N-terminal kinase (JNK) and NF-κB pathway. Supernatants from Der p 38-treated cells blocked filaggrin expression and neutrophil apoptosis. The anti-apoptotic effect of the Der p 38-released molecules on neutrophils was accomplished by inhibition of the caspase 9/3 pathway, and by increased MCL-1 expression and BCL-2/BAX expression ratio. In C57BL/6 wild type (WT) mice, Der p 38 induced a dose-dependent increase of AD-like skin lesions, with enhanced expressions of total and Der p 38-specific IgE. Der p 38 also diminished the expressions of skin barrier proteins and induced JNK activation. However, the AD-like features following cutaneous Der p 38 exposure were observed to be reduced in the TLR4 knockout (KO) group, as compared to the WT group. Skin infiltration of neutrophils, eosinophils and mast cells was increased in the WT mice, but was not portrayed in the TLR4 KO mice. These findings indicate that Der p 38 is a novel mite allergen that triggers AD by lowering skin barrier proteins and increasing inflammatory cells. Results of this study have thereby paved the way to unveil the pathogenic mechanisms of AD.

The Keratinocyte as a Crucial Cell in the Predisposition, Onset, Progression, Therapy and Study of the Atopic Dermatitis

The keratinocyte (KC) is the main functional and structural component of the epidermis, the most external layer of the skin that is highly specialized in defense against external agents, prevention of leakage of body fluids and retention of internal water within the cells. Altered epidermal barrier and aberrant KC differentiation are involved in the pathophysiology of several skin diseases, such as atopic dermatitis (AD). AD is a chronic inflammatory disease characterized by cutaneous and systemic immune dysregulation and skin microbiota dysbiosis. Nevertheless, the pathological mechanisms of this complex disease remain largely unknown. In this review, we summarize current knowledge about the participation of the KC in different aspects of the AD. We provide an overview of the genetic predisposing and environmental factors, inflammatory molecules and signaling pathways of the KC that participate in the physiopathology of the AD. We also analyze the link among the KC, the microbiota and the inflammatory response underlying acute and chronic skin AD lesions.

Human genetic and immunological dissection of papillomavirus-driven diseases: new insights into their pathogenesis

Human papillomaviruses (HPVs) are responsible for cutaneous and mucosal lesions. Persistent HPV infection remains a leading cause of uterine cancer in women, but also of cutaneous squamous cell carcinoma in patients with epidermodysplasia verruciformis (EV), and of rare and devastating benign tumors, such as 'tree-man' syndrome. HPV infections are usually asymptomatic or benign in the general population. Severe manifestations in otherwise healthy subjects can attest to inherited immunodeficiencies. The human genetic dissection of these cases has identified critical components of the immune response to HPVs, including the non-redundant roles of keratinocyte-intrinsic immunity in controlling β-HPVs, and of T cell-dependent adaptive immunity for controlling all HPV types. A key role of the CD28 T-cell costimulation pathway in controlling common warts due to HPVs was recently discovered. This review summarizes the state of the art in the human genetics of HPV infection, focusing on two key affected cell types: keratinocytes and T cells.

Immune-Regulatory and Molecular Effects of Antidepressants on the Inflamed Human Keratinocyte HaCaT Cell Line

Allergic contact dermatitis (ACD) is a T cell-mediated type of skin inflammation resulting from contact hypersensitivity (CHS) to antigens. There is strong comorbidity between ACD and major depression. Keratinocytes release immunomodulatory mediators including pro-inflammatory cytokines and chemokines, which modulate skin inflammation and are crucial cell type for the development of CHS. Our previous studies showed that fluoxetine and desipramine were effective in suppressing CHS in different mouse strains. However, the immune and molecular mechanisms underlying this effect remain to be explored. The aim of the current study was to determine the immune and molecular mechanisms of action of antidepressant drugs engaged in the inhibition of CHS response in the stimulated keratinocyte HaCaT cell line. The results show that LPS, TNF-α/IFN-γ, and DNFB stimulate HaCaT cells to produce large amounts of pro-inflammatory factors including IL-1β, IL-6, CCL2, and CXCL8. HaCaT stimulation was associated with increased expression of ICAM-1, a cell adhesion molecule, and decreased expression of E-cadherin. Imipramine, desipramine, and fluoxetine suppress the production of IL-1β, CCL2, as well as the expression of ICAM-1. LPS and TNF-α/IFN-γ activate p-38 kinase, but antidepressants do not regulate this pathway. LPS decreases E-cadherin protein expression and fluoxetine normalizes these effects. In summary, the antidepressant drugs examined in this study attenuate the stimulated secretion of pro-inflammatory cytokines, chemokines, and modulate adhesion molecule expression by the HaCaT cell line. Therefore, antidepressants may have some clinical efficacy in patients with ACD and patients with comorbid depression and contact allergy.

Genetic association and differential expression of HLAComplexGroup lncRNAs in pemphigus

BACKGROUND

Pemphigus is a group of bullous diseases characterized by acantholysis and skin blisters. As for other autoimmune diseases, the strongest genetic associations found so far for pemphigus foliaceus (PF) and vulgaris (PV) are with alleles of HLA genes. However, apart from protein-coding genes, the MHC region includes a set of poorly explored long non-coding RNA (lncRNA) genes, the HLA complex group (HCG).

OBJECTIVES

To investigate if HCG lncRNA alleles are associated with pemphigus susceptibility.

METHODS AND RESULTS

We analyzed SNPs in 13 HCG lncRNA genes, both in PV (Germany: 241 patients; 1,188 controls) and endemic PF (Brazil: 227 patients; 194 controls), applying multivariate logistic regression. We found 55 associations with PV (p_corr < 0.01) and nine with endemic PF (p_corr < 0.05), the majority located in TSBP1-AS1 (which includes HCG23) and HCG27 lncRNA genes, independently of HLA alleles previously associated with pemphigus. The association of TSBP1-AS1 rs3129949*A allele was further replicated in sporadic PF (p = 0.027, OR = 0.054; 75 patients and 150 controls, all from Germany). Next, we evaluated the expression levels of TSBP1-AS1, TSBP1, HCG23, and HCG27 in blood mononuclear cells of Brazilian patients and controls. HCG27 was upregulated in endemic PF (p = 0.035, log₂ FC = 1.3), while TSBP1-AS1 was downregulated in PV (p = 0.029, log₂ FC = -1.29). The same expression patterns were also seen in cultured keratinocytes stimulated with IgG antibodies from patients and controls from Germany. TSBP1 mRNA levels were also decreased in endemic PF blood cells (p = 0.042, log₂ FC = -2.14). TSBP1-AS1 and HCG27 were also observed downregulated in CD19⁺ cells of endemic PF (p < 0.01, log₂ FC = -0.226 and -0.46 respectively).

CONCLUSIONS

HCG lncRNAs are associated with susceptibility to pemphigus, being TSBP1-AS1 and HCG27 also differentially expressed in distinct cell populations. These results suggest a role for HCG lncRNAs in pemphigus autoimmunity.

The Phosphatidylserine Receptor TIM-1 Enhances Authentic Chikungunya Virus Cell Entry

Chikungunya virus (CHIKV) is a re-emerging, mosquito-transmitted, enveloped positive stranded RNA virus. Chikungunya fever is characterized by acute and chronic debilitating arthritis. Although multiple host factors have been shown to enhance CHIKV infection, the molecular mechanisms of cell entry and entry factors remain poorly understood. The phosphatidylserine-dependent receptors, T-cell immunoglobulin and mucin domain 1 (TIM-1) and Axl receptor tyrosine kinase (Axl), are transmembrane proteins that can serve as entry factors for enveloped viruses. Previous studies used pseudoviruses to delineate the role of TIM-1 and Axl in CHIKV entry. Conversely, here, we use the authentic CHIKV and cells ectopically expressing TIM-1 or Axl and demonstrate a role for TIM-1 in CHIKV infection. To further characterize TIM-1-dependent CHIKV infection, we generated cells expressing domain mutants of TIM-1. We show that point mutations in the phosphatidylserine binding site of TIM-1 lead to reduced cell binding, entry, and infection of CHIKV. Ectopic expression of TIM-1 renders immortalized keratinocytes permissive to CHIKV, whereas silencing of endogenously expressed TIM-1 in human hepatoma cells reduces CHIKV infection. Altogether, our findings indicate that, unlike Axl, TIM-1 readily promotes the productive entry of authentic CHIKV into target cells.

Human Keratinocytes Inhibit CD4+ T-Cell Proliferation through TGFB1 Secretion and Surface Expression of HLA-G1 and PD-L1 Immune Checkpoints

Human skin protects the body against infection and injury. This protection involves immune and epithelial cells, but their interactions remain largely unknown. Here, we show that cultured epidermal keratinocytes inhibit allogenic CD4⁺ T-cell proliferation under both normal and inflammatory conditions. Inhibition occurs through the secretion of soluble factors, including TGFB1 and the cell-surface expression of HLA-G1 and PD-L1 immune checkpoints. For the first time, we here describe the expression of the HLA-G1 protein in healthy human skin and its role in keratinocyte-driven tissue immunomodulation. The overexpression of HLA-G1 with an inducible vector increased the immunosuppressive properties of keratinocytes, opening up perspectives for their use in allogeneic settings for cell therapy.

Aspirin alleviates skin inflammation and angiogenesis in rosacea

Rosacea is a chronic, relapsing inflammatory skin disease featured by abnormal activation of immune responses, vascular dysfunction and prominent permeability barrier alterations. Aspirin, as the first nonsteroidal anti-inflammatory drug (NSAID), is widely used for various inflammatory conditions due to its anti-inflammatory and anti-angiogenic properties. However, its effects on rosacea are unclear. In this study, we demonstrated that aspirin dramatically improved pathological phenotypes in LL37-induced rosacea-like mice. The RNA-sequencing analysis revealed that aspirin alleviated rosacea-like skin dermatitis mainly via modulating immune responses. Mechanically, we showed that aspirin decreased the production of chemokines and cytokines associated with rosacea, and suppressed the Th1- and Th17-polarized immune responses in LL37-induced rosacea-like mice. Besides, aspirin administration decreased the microvessels density and the VEGF expression in rosacea-like skin. We further demonstrated that aspirin inhibited the activation of NF-κB signaling and the release of its downstream pro-inflammatory cytokines. Collectively we showed that aspirin exerts a curative effect on rosacea by attenuating skin inflammation and angiogenesis, suggesting a promising therapeutic candidate for the treatment of rosacea.

iRHOM2: A Regulator of Palmoplantar Biology, Inflammation, and Viral Susceptibility

The palmoplantar epidermis is a specialized area of the skin that undergoes high levels of mechanical stress. The palmoplantar keratinization and esophageal cancer syndrome, tylosis with esophageal cancer, is linked to mutations in RHBDF2 encoding the proteolytically inactive rhomboid protein, iRhom2. Subsequently, iRhom2 was found to affect palmoplantar thickening to modulate the stress keratin response and to mediate context-dependent stress pathways by p63. iRhom2 is also a direct regulator of the sheddase, ADAM17, and the antiviral adaptor protein, stimulator of IFN genes. In this perspective, the pleiotropic functions of iRhom2 are discussed with respect to the skin, inflammation, and the antiviral response.

Monovalent antibody-conjugated lipid-polymer nanohybrids for active targeting to desmoglein 3 of keratinocytes to attenuate psoriasiform inflammation

To improve the treatment of psoriasiform inflammation, we developed actively targeted nanocarriers loaded with the phosphodiesterase 4 inhibitor AN2728. Methods: Phospholipid-poly(lactic-co-glycolic acid) nanohybrids were prepared and conjugated with monovalent anti-desmoglein 3 antibody to bind keratinocytes. Results: The actively targeted nanohybrids were 229 nm in mean size with a nearly neutral surface charge. Flow cytometry and confocal microscopy showed a 9-fold increase in keratinocyte uptake of targeted nanohybrids relative to non-targeted nanoparticles. The nanoparticles localized mainly in lysosomes after internalization. AN2728-loaded antibody-conjugated nanocarriers inhibited cytokine/chemokine overexpression in activated keratinocytes without affecting cell viability. The targeted nanohybrids also suppressed neutrophil migration by reducing CXCL1 and CXCL2 release from keratinocytes. Following subcutaneous administration in mice, the nanohybrids distributed to the epidermis and hair follicles. In a psoriasis-like skin mouse model, the actively targeted nanoparticles were superior to free drug and non-targeted nanoparticles in mitigating skin inflammation. Intervention with the targeted nanosystem reduced the epidermal thickness of the psoriasiform lesion from 191 to 42 µm, decreased the Psoriasis Area Severity Index by 74%, restored barrier function, and returned chemokine levels to baseline. Conclusions: Our developed nanosystem was safe and demonstrated efficient targeting properties for the treatment of cutaneous inflammation.

JNK1 Signaling Downstream of the EGFR Pathway Contributes to Aldara®-Induced Skin Inflammation

c-Jun N-terminal protein kinase 1 (JNK1) is involved in multiple biological processes but its implication in inflammatory skin diseases is still poorly defined. Herein, we studied the role of JNK1 in the context of Aldara®-induced skin inflammation. We observed that constitutive ablation of JNK1 reduced Aldara®-induced acanthosis and expression of inflammatory markers. Conditional deletion of JNK1 in myeloid cells led to reduced skin inflammation, a finding that was associated with impaired Aldara®-induced inflammasome activation in vitro. Next, we evaluated the specific role of JNK1 in epidermal cells. We observed reduced Aldara®-induced acanthosis despite similar levels of inflammatory markers. Transcriptomic and epigenomic analysis of keratinocytes revealed the potential involvement of JNK1 in the EGFR signaling pathway. Finally, we show that inhibition of the EGFR pathway reduced Aldara®-induced acanthosis. Taken together, these data indicate that JNK1 plays a dual role in the context of psoriasis by regulating the production of inflammatory cytokines by myeloid cells and the sensitivity of keratinocytes to EGFR ligands. These results suggest that JNK1 could represent a valuable therapeutic target in the context of psoriasis.

A novel method to identify Post-Aire stages of medullary thymic epithelial cell differentiation

Autoimmune regulator+ (Aire) medullary thymic epithelial cells (mTECs) play a critical role in tolerance induction. Several studies demonstrated that Aire+ mTECs differentiate further into Post-Aire cells. Yet, the identification of terminal stages of mTEC maturation depends on unique fate-mapping mouse models. Herein, we resolve this limitation by segmenting the mTEChi (MHCIIhi CD80hi ) compartment into mTECA/hi (CD24- Sca1- ), mTECB/hi (CD24+ Sca1- ), and mTECC/hi (CD24+ Sca1+ ). While mTECA/hi included mostly Aire-expressing cells, mTECB/hi contained Aire+ and Aire- cells and mTECC/hi were mainly composed of cells lacking Aire. The differential expression pattern of Aire led us to investigate the precursor-product relationship between these subsets. Strikingly, transcriptomic analysis of mTECA/hi , mTECB/hi , and mTECC/hi sequentially mirrored the specific genetic program of Early-, Late- and Post-Aire mTECs. Corroborating their Post-Aire nature, mTECC/hi downregulated the expression of tissue-restricted antigens, acquired traits of differentiated keratinocytes, and were absent in Aire-deficient mice. Collectively, our findings reveal a new and simple blueprint to survey late stages of mTEC differentiation.

Suppression of IL-17A-induced CCL20 production by cytokine inducible SH2-containing protein 1 in epidermal keratinocytes

BACKGROUND

Lesions of atopic dermatitis have fewer Th17 cells than those of psoriasis, resulting in frequent skin infections. Expression of CCL20, a chemokine that is important for recruiting Th17 cells, is suppressed in the lesions of atopic dermatitis. We previously reported that IL-4 induces the expression of cytokine-inducible SH2-containing protein 1 (CIS1), a member of the CIS/SOCS family, in epidermal keratinocytes.

OBJECTIVE

To investigate whether CIS1 influences CCL20 production in epidermal keratinocytes.

METHODS

Expression of CIS1 was examined in atopic dermatitis skin and in cultured keratinocytes. The effects of overexpression of CIS1 on CCL20 production by IL-17A, and on signaling pathways inhibited by CIS1, were assessed in vitro.

RESULTS

Expression of CIS1 was enhanced in the basal layer of the lesional epidermis of skin with atopic dermatitis. When CIS1 was expressed in keratinocytes using adenoviral vectors, IL-17A-induced CCL20 expression, but not HBD2 or S100A7 expression, was significantly suppressed. TNF-α/IL-1-induced CCL20 production was not altered by CIS1. Overexpression of CIS1 attenuated IL-17A-induced ERK phosphorylation. ERK phosphorylation was mediated by the Act1 and Src family kinase pathways. CIS1 overexpression suppressed Src phosphorylation. Among the Src family kinases, the Yes kinase may have an important role because knockdown of Yes in epidermal keratinocytes resulted in suppression of ERK phosphorylation and CCL20 mRNA expression by IL-17A.

CONCLUSION

CIS1 induced by Th2 cytokines has the ability to change the response of epidermal keratinocytes to IL-17A by suppression of Src family kinases.

Skin Sensitization Tests: The LLNA and the RhE IL-18 Potency Assay

Contact allergy is of considerable importance to the toxicologist, and regulatory authorities worldwide require testing for skin sensitization potential and appropriate hazard labeling to enable management of the risk to human health. Although traditionally the identification of skin-sensitizing chemicals has been carried out using animal models, in Europe legislative changes have promoted, and now require, the use of non-animal methods (i.e., Cosmetic Directive, REACH). Several in vitro alternatives for hazard identification have now been validated, but do not provide information on the potency of a skin sensitizer. Here, we describe an animal model, the local lymph node assay (LLNA), and an in vitro model, the RhE IL-18 potency assay, in the context of the identification and potency classification of skin sensitizers. These two assays have been chosen among the different available tests as representative of an alternative in vivo model (the LLNA) and a promising in vitro method with the potential of both hazard identification and potency classification.

Identification of a primary antigenic target of epitope spreading in endemic pemphigus foliaceus

Epitope spreading is an important mechanism for the development of autoantibodies (autoAbs) in autoimmune diseases. The study of epitope spreading in human autoimmune diseases is limited due to the major challenge of identifying the initial/primary target epitopes on autoantigens in autoimmune diseases. We have been studying the development of autoAbs in an endemic human autoimmune disease, Brazilian pemphigus foliaceus (or Fogo Selvagem (FS)). Our previous findings demonstrated that patients before (i.e. preclinical) and at the onset of FS have antibody (Ab) responses against other keratinocyte adhesion molecules in addition to the main target autoantigen of FS, desmoglein 1 (Dsg1), and anti-Dsg1 monoclonal Abs (mAbs) cross-reacted with an environmental antigen LJM11, a sand fly saliva protein. Since sand fly is prevalent in FS endemic regions, individuals in these regions could develop Abs against LJM11. The anti-LJM11 Abs could recognize different epitopes on LJM11, including an epitope that shares the structure similarity with an epitope on Dsg1 autoantigen. Thus, Ab response against this epitope on LJM11 could be the initial autoAb response detected in individuals in FS endemic regions, including those who eventually developed FS. Accordingly, this LJM11 and Dsg1 cross-reactive epitope on Dsg1 could be the primary target of the autoimmune response in FS. This investigation aimed to determine whether the autoAb responses against keratinocyte adhesion molecules are linked and originate from the immune response to LJM11. The anti-Dsg1 mAbs from preclinical FS and FS individuals were employed to determine their specificity or cross-reactivity to LJM11 and keratinocyte adhesion molecules. The cross-reactive epitopes on autoantigens were mapped. Our results indicate that all tested mAbs cross-reacted with LJM11 and keratinocyte adhesion molecules, and we identified an epitope on these keratinocyte adhesion molecules which is mimicked by LJM11. Thus, the cross-reactivity could be the mechanism by which the immune response against an environmental antigen triggers the initial autoAb responses. Epitope spreading leads to the pathogenic autoAb development and ensuing FS among genetically susceptible individuals.

The Immune Functions of Keratinocytes in Skin Wound Healing

As the most dominant cell type in the skin, keratinocytes play critical roles in wound repair not only as structural cells but also exerting important immune functions. This review focuses on the communications between keratinocytes and immune cells in wound healing, which are mediated by various cytokines, chemokines, and extracellular vesicles. Keratinocytes can also directly interact with T cells via antigen presentation. Moreover, keratinocytes produce antimicrobial peptides that can directly kill the invading pathogens and contribute to wound repair in many aspects. We also reviewed the epigenetic mechanisms known to regulate keratinocyte immune functions, including histone modifications, non-protein-coding RNAs (e.g., microRNAs, and long noncoding RNAs), and chromatin dynamics. Lastly, we summarized the current evidence on the dysregulated immune functions of keratinocytes in chronic nonhealing wounds. Based on their crucial immune functions in skin wound healing, we propose that keratinocytes significantly contribute to the pathogenesis of chronic wound inflammation. We hope this review will trigger an interest in investigating the immune roles of keratinocytes in chronic wound pathology, which may open up new avenues for developing innovative wound treatments.

GLS1-mediated glutaminolysis unbridled by MALT1 protease promotes psoriasis pathogenesis

Psoriasis is a severe disease associated with the disturbance of metabolism and inflammation, but the molecular mechanisms underlying these aspects of psoriasis pathology are poorly understood. Here, we report that glutaminase 1-mediated (GLS1-mediated) glutaminolysis was aberrantly activated in patients with psoriasis and in psoriasis-like mouse models, which promoted Th17 and γδ T17 (IL-17A-producing γδ T) cell differentiation through enhancement of histone H3 acetylation of the Il17a promoter, thereby contributing to the immune imbalance and development of psoriasis. We further demonstrate that mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) protease was constitutively active in psoriatic CD4+ and γδ T cells, thereby supporting GLS1 expression by stabilizing c-Jun, which directly binds to the GLS1 promoter region. Blocking the activity of either GLS1 or MALT1 protease resolved Th17 and γδ T17 cell differentiation and epidermal hyperplasia in the psoriasis-like mouse models. Finally, IL-17A enhanced GLS1 expression via the MALT1/cJun pathway in keratinocytes, resulting in hyperproliferation of and chemokine production by keratinocytes. Our findings identify the role of the MALT1/cJun/GLS1/glutaminolysis/H3 acetylation/T17 axis in psoriasis pathogenesis and reveal potential therapeutic targets for this disease.

Electroceutical Management of Bacterial Biofilms and Surgical Infection

Significance: In the host-microbe microenvironment, bioelectrical factors influence microbes and hosts as well as host-microbe interactions. This article discusses relevant mechanistic underpinnings of this novel paradigm. It also addresses how such knowledge may be leveraged to develop novel electroceutical solutions to manage biofilm infection. Recent Advances: Systematic review and meta-analysis of several hundred wound studies reported a 78.2% prevalence of biofilms in chronic wounds. Biofilm infection is a major cause of delayed wound healing. In the host-microbe microenvironment, bioelectrical factors influence interactions between microbes and hosts. Critical Issues: Rapid biological responses are driven by electrical signals generated by ion currents moving across cell membranes. Bacterial life, growth, and function rely on a bioelectrical milieu, which when perturbed impairs their ability to form a biofilm, a major threat to health care. Electrokinetic stability of several viral particles depend on electrostatic forces. Weak electrical field strength, otherwise safe for humans, can be anti-microbial in this context. In the host, the electric field enhanced keratinocyte migration, bolstered immune defenses, improved mitochondrial function, and demonstrated multiple other effects consistent with supporting wound healing. A deeper mechanistic understanding of bioelectrical principles will inform the design of next-generation electroceuticals. Future Directions: This is an opportune moment in time as there is a surge of interest in electroceuticals in medicine. Projected to reach $35.5 billion by 2025, electroceuticals are becoming a cynosure in the global market. The World Health Organization reports that more than 50% of surgical site infections can be antibiotic resistant. Electroceuticals offer a serious alternative.

TEAD4 transcriptional regulates SERPINB3/4 and affect crosstalk between keratinocytes and T cells in psoriasis

Psoriasis is a common chronic inflammatory disease with the prevalence rate of approximately 1-3 %. Currently, it is generally believed that the pathogenesis of psoriasis is a T-cell immune-mediated skin disease mediated by multiple genes and factors, and the interaction between keratinocytes and T cells. TEA domain family member 4 (TEAD4) is a transcription factor which regulates the expression of downstream genes in Hippo pathway and affects several biological processes, such as regulating cell differentiation and embryonic development. However, few studies have reported the role of TEAD4 in psoriasis and its possible regulatory mechanism. In this study, we found the expression level of TEAD4 in the skin of psoriasis was significantly higher than that of normal skin. In patients with the pathological keratinocytes, TEAD4 can transcriptionally regulate the expression of SERPINB3/4 and affect the secretion of chemokines, and the depletion of SERPINB3/4 inhibited the secretion of chemokines. In addition, the supernatant of keratinocytes of patients can significantly increase the migration ability of T cells, and the supernatant of T cells cultured by the supernatant of keratinocytes of patients can significantly enhance the proliferation ability of keratinocytes. Therefore, our results suggested that TEAD4 is a key regulatory factor in progression of psoriasis, and the crosstalk between keratinocytes and T cells mediated by TEAD4 plays a critical role in the psoriasis pathogenesis.

Human papillomavirus type 38 alters wild-type p53 activity to promote cell proliferation via the downregulation of integrin alpha 1 expression

Tumor suppressors can exert pro-proliferation functions in specific contexts. In the beta human papillomavirus type 38 (HPV38) experimental model, the viral proteins E6 and E7 promote accumulation of a wild-type (WT) p53 form in human keratinocytes (HKs), promoting cellular proliferation. Inactivation of p53 by different means strongly decreases the proliferation of HPV38 E6/E7 HKs. This p53 form is phosphorylated at S392 by the double-stranded RNA-dependent protein kinase PKR, which is highly activated by HPV38. PKR-mediated S392 p53 phosphorylation promotes the formation of a p53/DNMT1 complex, which inhibits expression of integrin alpha 1 (ITGA1), a repressor of epidermal growth factor receptor (EGFR) signaling. Ectopic expression of ITGA1 in HPV38 E6/E7 HKs promotes EGFR degradation, inhibition of cellular proliferation, and cellular death. Itga1 expression was also inhibited in the skin of HPV38 transgenic mice that have an elevated susceptibility to UV-induced skin carcinogenesis. In summary, these findings reveal the existence of a specific WT p53 form that displays pro-proliferation properties.

Downregulation of HLA-I by the molluscum contagiosum virus mc080 impacts NK-cell recognition and promotes CD8+ T-cell evasion

Molluscum contagiosum virus (MCV) is a common cause of benign skin lesions in young children and currently the only endemic human poxvirus. Following the infection of primary keratinocytes in the epidermis, MCV induces the proliferation of infected cells and this results in the production of wart-like growths. Full productive infection is observed only after the infected cells differentiate. During this prolonged replication cycle the virus must avoid elimination by the host immune system. We therefore sought to investigate the function of the two major histocompatibility complex class-I-related genes encoded by the MCV genes mc033 and mc080. Following insertion into a replication-deficient adenovirus vector, codon-optimized versions of mc033 and mc080 were expressed as endoglycosidase-sensitive glycoproteins that localized primarily in the endoplasmic reticulum. MC080, but not MC033, downregulated cell-surface expression of endogenous classical human leucocyte antigen (HLA) class I and non-classical HLA-E by a transporter associated with antigen processing (TAP)-independent mechanism. MC080 exhibited a capacity to inhibit or activate NK cells in autologous assays in a donor-specific manner. MC080 consistently inhibited antigen-specific T cells being activated by peptide-pulsed targets. We therefore propose that MC080 acts to promote evasion of HLA-I-restricted cytotoxic T cells.

A potent antagonist antibody targeting connexin hemichannels alleviates Clouston syndrome symptoms in mutant mice

BACKGROUND

Numerous currently incurable human diseases have been causally linked to mutations in connexin (Cx) genes. In several instances, pathological mutations generate abnormally active Cx hemichannels, referred to also as "leaky" hemichannels. The goal of this study was to assay the in vivo efficacy of a potent antagonist antibody targeting Cx hemichannels.

METHODS

We employed the antibody to treat Cx30A88V/A88V adult mutant mice, the only available animal model of Clouston syndrome, a rare orphan disease caused by Cx30 p.A88V leaky hemichannels. To gain mechanistic insight into antibody action, we also performed patch clamp recordings, Ca2+ imaging and ATP release assay in vitro.

FINDINGS

Two weeks of antibody treatment sufficed to repress cell hyperproliferation in skin and reduce hypertrophic sebaceous glands (SGs) to wild type (wt) levels. These effects were obtained whether mutant mice were treated topically, by application of an antibody cream formulation, or systemically, by intraperitoneal antibody injection. Experiments with mouse primary keratinocytes and HaCaT cells revealed the antibody blocked Ca2+ influx and diminished ATP release through leaky Cx30 p.A88V hemichannels.

INTERPRETATION

Our results show anti-Cx antibody treatment was effective in vivo and sufficient to counteract the effects of pathological connexin expression in Cx30A88V/A88V mice. In vitro experiments suggest antibodies gained control over leaky hemichannels and contributed to restoring epidermal homeostasis. Therefore, regulating cell physiology by antibodies targeting the extracellular domain of Cxs may enforce an entirely new therapeutic strategy. These findings support the further development of antibodies as drugs to address unmet medical needs for Cx-related diseases. FUND: Fondazione Telethon, GGP19148; University of Padova, SID/BIRD187130; Consiglio Nazionale delle Ricerche, DSB.AD008.370.003\TERABIO-IBCN; National Science Foundation of China, 31770776; Science and Technology Commission of Shanghai Municipality, 16DZ1910200.

Thermal Burn Injury Generates Bioactive Microvesicles: Evidence for a Novel Transport Mechanism for the Lipid Mediator Platelet-Activating Factor (PAF) That Involves Subcellular Particles and the PAF Receptor

Thermal burn injuries are an important environmental stressor that can result in considerable morbidity and mortality. The exact mechanism by which an environmental stimulus to skin results in local and systemic effects is an area of active research. One potential mechanism to allow skin keratinocytes to disperse bioactive substances is via microvesicle particles, which are subcellular bodies released directly from cellular membranes. Our previous studies have indicated that thermal burn injury of the skin keratinocyte in vitro results in the production of the lipid mediator platelet-activating factor (PAF). The present studies demonstrate that thermal burn injury to keratinocytes in vitro and human skin explants ex vivo, and mice in vivo generate microvesicle particles. Use of pharmacologic and genetic tools indicates that the optimal release of microvesicles is dependent upon the PAF receptor. Of note, burn injury-stimulated microvesicle particles do not carry appreciable protein cytokines yet contain high levels of PAF. These studies describe a novel mechanism involving microvesicle particles by which a metabolically labile bioactive lipid can travel from cells in response to environmental stimuli.

An in vitro methodology for discovering broadly-neutralizing monoclonal antibodies

Broadly-neutralizing monoclonal antibodies are of high therapeutic utility against infectious diseases caused by bacteria and viruses, as well as different types of intoxications. Snakebite envenoming is one such debilitating pathology, which is currently treated with polyclonal antibodies derived from immunized animals. For the development of novel envenoming therapies based on monoclonal antibodies with improved therapeutic benefits, new discovery approaches for broadly-neutralizing antibodies are needed. Here, we present a methodology based on phage display technology and a cross-panning strategy that enables the selection of cross-reactive monoclonal antibodies that can broadly neutralize toxins from different snake species. This simple in vitro methodology is immediately useful for the development of broadly-neutralizing (polyvalent) recombinant antivenoms with broad species coverage, but may also find application in the development of broadly-neutralizing antibodies against bacterial, viral, and parasitic agents that are known for evading therapy via resistance mechanisms and antigen variation.

Atopic dermatitis displays stable and dynamic skin transcriptome signatures

BACKGROUND

Skin transcriptome studies in atopic dermatitis (AD) showed broad dysregulation as well as "improvement" under therapy. These observations were mainly made in trials and based on microarray data.

OBJECTIVES

Our aim was to explore the skin transcriptome and the impact of systemic treatment in patients of the TREATgermany registry.

METHODS

Biopsy specimens from 59 patients with moderate-to-severe AD before and 30 patients 12 weeks after start of systemic treatment (dupilumab [n = 22] or cyclosporine [n = 8]) and from 31 healthy controls were subjected to mRNA sequencing. Differential expression, pathway enrichment, correlation, and coexpression network analysis were conducted.

RESULTS

Both lesional and nonlesional skin showed a stable "core" signature characterized by disturbed epidermal differentiation and activation of IL-31/IL-1 signaling. A second dynamic signature showed progressive enrichment for type 2 inflammation, T_H17 signaling, and natural killer cell function. Markers correlated with disease activity have functions in epidermal barrier properties and immune modulation. IL4RA was among the top 3 central dysregulated genes. Cyclosporine led to a more pronounced global transcriptome reversion and normalized T_H17 cell/IL23 signaling, whereas dupilumab led to a stronger increase in level of epidermal differentiation markers. Both treatments strongly decreased levels of type 2 markers, but overall the residual profile was still profoundly different from that of healthy skin. Lower levels of IL4RA and IL13 and high IL36A expression were related to a stronger clinical response to dupilumab.

CONCLUSION

The AD core signature is characterized by dysregulation of genes related to keratinocyte differentiation and itch signaling. A dynamic signature reflects progressive immune responses dominated by type 2 cytokines with an additional role of T_H17 and natural killer cell signaling.

Abrogation of Constitutive and Induced Type I and Type III Interferons and Interferon-Stimulated Genes in Keratinocytes by Canine Papillomavirus 2 E6 and E7

Cutaneous papillomaviruses can cause severe, persistent infections and skin cancer in immunodeficient patients, including people with X-linked severe combined immunodeficiency (XSCID). A similar phenotype is observed in a canine model of XSCID; these dogs acquire severe cutaneous papillomavirus infections that can progress to cancer in association with canine papillomavirus type 2 (CPV2). This canine model system provides a natural spontaneous animal model for investigation of papillomavirus infections in immunodeficient patients. Currently, it is unknown if CPV2 can subvert the innate immune system and interfere with its ability to express antiviral cytokines, which are critical in the host defense against viral pathogens. The aim of the current study was to determine if the oncogenes E6 and E7 from CPV2 interfere with expression of antiviral cytokines in keratinocytes, the target cells of papillomavirus infections. We determined that E6 but not E7 interferes with the constitutive expression of some antiviral cytokines, including interferon (IFN)-β and the IFN-stimulated gene IFIT1. Both E6 and E7 interfere with the transcriptional upregulation of the antiviral cytokines in response to stimulation with the dsDNA Poly(dA:dT). In contrast, while E6 also interferes with the transcriptional upregulation of antiviral cytokines in response to stimulation with the dsRNA Poly(I:C), E7 interferes with only a subset of these antiviral cytokines. Finally, we demonstrated that E7 but not E6 abrogates signaling through the type I IFN receptor. Taken together, CPV2 E6 and E7 both impact expression of antiviral cytokines in canine keratinocytes, albeit likely through different mechanisms.

The anti-TH17 polarization effect of Indigo naturalis and tryptanthrin by differentially inhibiting cytokine expression

ETHNOPHARMACOLOGICAL RELEVANCE

The Chinese herbal medicine Qing-Dai (also known as Indigo naturalis) extracted from indigo-bearing plants including Baphicacanthus cusia (Ness) Bremek was previously reported to exhibit anti-psoriatic effects in topical treatment. TH17 was later established as a key player in the pathogenesis of psoriasis. We investigated the anti-TH17 effect of Indigo naturalis and its active compounds. The aim of this study is to evaluate the toxicity of Indigo naturalis (IN) and its derivatives on five cell types involved in psoriasis, and to study the anti-inflammatory mechanism for the toxicity.

MATERIALS AND METHODS

Following the fingerprint and quantity analysis of indirubin, indigo, and tryptanthrin in IN extract, we used MTS kits to measure the anti-proliferative effect of IN and three active compounds on five different cell types identified in psoriatic lesions. Quantitative RT-PCR analysis was used to measure the expression of various genes identified in the activated keratinocytes and TH17 polarized gene expression in RORγt-expressing T cells.

RESULTS

We showed that IN differentially inhibited the proliferation of keratinocytes and endothelial cells but not monocytes, fibroblasts nor Jurkat T cells. Among three active compounds identified in IN, tryptanthrin was the most potent compound to reduce their proliferation. In addition to differentially reducing IL6 and IL8 expression, both IN and tryptanthrin also potently decreased the expression of anti-microbial S100A9 peptide, CCL20 chemokine, IL1B and TNFA cytokines, independent of NF-κB-p65-activation. Their attenuating effect was also detected on the expression of signature cytokines or chemokines induced during RORγT-induced TH17 polarization.

CONCLUSIONS

We were the first to confirm a direct anti-TH17 effect of both IN herbal extract and tryptanthrin.

IL-36 signaling in keratinocytes controls early IL-23 production in psoriasis-like dermatitis

IL-36R signaling plays an important role in the pathogenesis of psoriasis. We ought to assess the specific function of IL-36R in keratinocytes for the pathology of Aldara-induced psoriasis-like dermatitis. Il36r ΔK mice presenting deletion of IL-36R in keratinocytes were similarly resistant to Aldara-induced ear inflammation as Il36r -/- mice, but acanthosis was only prevented in Il36r -/- mice. FACS analysis revealed that IL-36R signaling in keratinocytes is mandatory for early neutrophil infiltration in Aldara-treated ears. RNASeq and qRT-PCR experiments demonstrated the crucial role of IL-36R signaling in keratinocytes for induction of IL-23, IL-17, and IL-22 at early time points. Taken together, our results demonstrate that IL-36R signaling in keratinocytes plays a major role in the induction of Aldara-induced psoriasis-like dermatitis by triggering early production of IL-23/IL-17/IL-22 cytokines and neutrophil infiltration.

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.

Isatis tinctoria L.-derived Petroleum Ether Extract Mediates Anti-inflammatory Effects via Inhibition of Interleukin-6, Interleukin-33 and Mast Cell Degranulation

Isatis tinctoria L. (woad) has been used in medicine for centuries and has demonstrated anti-inflammatory effects. However, to date, no well-defined extracts with precise analysis of active substances have been developed. The aim of this study was to develop novel extracts of Isatis tinctoria L., and to characterize their active ingredients and anti-inflammatory properties. Various extracts of Isatis tinctoria L. were analysed for their active ingredients, and screened for anti-inflammatory effects using cyclooxygenase-2 activity assays. A petroleum ether extract was found to have the best effects, and was tested in a mouse model of acute allergic contact dermatitis. In the mouse model the petroleum ether extract resulted in significantly reduced ear swelling, oedema and inflammatory cell density. In mouse skin and human keratinocyte cultures, petroleum ether extract inhibited pro-inflammatory cytokine expression. Furthermore, human mast cell degranulation was significantly inhibited in LAD2 cell cultures. In conclusion, novel woad extracts were developed and shown to have anti-inflammatory properties in a contact hypersensitivity animal model and human keratinocytes. The production of such extracts and further characterization of their specific properties will enable determination of their potential dermatological effects in the treatment of inflamed and irritated skin.

IL-27 signaling activates skin cells to induce innate antiviral proteins and protects against Zika virus infection

In the skin, antiviral proteins and other immune molecules serve as the first line of innate antiviral defense. Here, we identify and characterize the induction of cutaneous innate antiviral proteins in response to IL-27 and its functional role during cutaneous defense against Zika virus infection. Transcriptional and phenotypic profiling of epidermal keratinocytes treated with IL-27 demonstrated activation of antiviral proteins OAS1, OAS2, OASL, and MX1 in the skin of both mice and humans. IL-27-mediated antiviral protein induction was found to occur in a STAT1- and IRF3-dependent but STAT2-independent manner. Moreover, using IL27ra mice, we demonstrate a significant role for IL-27 in inhibiting Zika virus morbidity and mortality following cutaneous, but not intravenous, inoculation. Together, our results demonstrate a critical and previously unrecognized role for IL-27 in cutaneous innate antiviral immunity against Zika virus.

Fucoxanthin Ameliorates Atopic Dermatitis Symptoms by Regulating Keratinocytes and Regulatory Innate Lymphoid Cells

Fucoxanthin (FX) is a xanthophyll that is contained abundantly in marine plants. The biological action of FX includes its antioxidant and anti-lipogenic activities, while the precise action of its mechanisms on skin cells has not yet been clarified. The current study examined the effect of FX in comparison with tacrolimus (TAC) on NC/Nga mice, which are an atopic dermatitis (AD) model. FX topical treatment dramatically ameliorated itching behavior over the TAC treatment, which was insufficient for improvement of AD symptoms. In Nc/Nga mice, FX or TAC applied to the skin inhibited eosinophil infiltration with decreased expression of Il-33. FX also stimulated Il-2, Il-5, Il-13, Il-10, and TGF-β expression levels, and Sca1⁺Il-10⁺TGF-β⁺ regulatory innate lymphoid cells (ILCreg) were dominantly observed in FX treated skin epidermal keratinocytes and dermal layers. This combined evidence demonstrated that FX exerts anti-inflammatory effects on keratinocytes and ameliorates AD symptoms by regulating ILCreg to normalize immune responses in an atopic dermatitis model.

ILC2 activation by keratinocyte-derived IL-25 drives IL-13 production at sites of allergic skin inflammation

Background

Atopic dermatitis skin lesions demonstrate increased expression of IL-25 by keratinocytes and increased numbers of type 2 innate lymphoid cells (ILC2s) that express high levels of IL-25 receptor (IL-25R). IL-13 is expressed in atopic dermatitis skin lesions and plays an important role in pathogenesis of the disease.

Objective

Our aim was to determine the role of IL-25 and ILC2s in a mouse model of antigen-driven allergic skin inflammation.

Methods

Wild-type mice; mice that express an Il13-driven enhanced green fluorescent protein; and mice that lack IL-25R, IL-25 in keratinocytes, or IL-13 or IL-25R in ILC2s were subjected to acute or chronic epicutaneous sensitization with ovalbumin. Sensitized skin was examined by histology for epidermal thickening. Cellular infiltrates were analyzed for surface markers and intracellular expression of enhanced green fluorescent protein by flow cytometry. Gene expression was quantitated by RT quantitative PCR.

Result

In both acute and chronic antigen-driven allergic skin inflammation, signaling by keratinocyte-derived IL-25 in ILC2s is important for epidermal hyperplasia, dermal infiltration by CD4⁺ T cells, and cutaneous expression of Il13 and the IL-13–dependent T_H2-cell–attracting chemokines Cc17 and Ccl22. ILCs are the major source of IL-13 in acutely sensitized mouse skin, whereas T cells are its major source in chronically sensitized mouse skin.

Conclusion

ILC2 activation by IL-25 is essential for IL-13 expression at sites of allergic skin inflammation.

Recapitulating T cell infiltration in 3D psoriatic skin models for patient-specific drug testing

Drug screening studies for inflammatory skin diseases are currently performed using model systems that only partially recapitulate human diseased skin. Here, we developed a new strategy to incorporate T cells into human 3D skin constructs (HSCs), which enabled us to closely monitor and quantitate T cell responses. We found that the epidermis promotes the activation and infiltration of T cells into the skin, and provides a directional cue for their selective migration towards the epidermis. We established a psoriatic HSC (pHSC) by incorporating polarized Th1/Th17 cells or CCR6+CLA+ T cells derived from psoriasis patients into the constructs. These pHSCs showed a psoriatic epidermal phenotype and characteristic cytokine profiles, and responded to various classes of psoriasis drugs, highlighting the potential utility of our model as a drug screening platform. Taken together, we developed an advanced immunocompetent 3D skin model to investigate epidermal-T cell interactions and to understand the pathophysiology of inflammatory skin diseases in a human-relevant and patient-specific context.

Brief communication: Long-term absence of Langerhans cells alters the gene expression profile of keratinocytes and dendritic epidermal T cells

Tissue-resident and infiltrating immune cells are continuously exposed to molecules derived from the local cells that often come in form of secreted factors, such as cytokines. These factors are known to impact the immune cells’ biology. However, very little is known about whether the tissue resident immune cells in return also affect the local environment. In this study, with the help of RNA-sequencing, we show for the first time that long-term absence of epidermal resident Langerhans cells led to significant gene expression changes in the local keratinocytes and resident dendritic epidermal T cells. Thus, immune cells might play an active role in maintaining tissue homeostasis, which should be taken in consideration at data interpretation.

miR-203 Acts as an Inhibitor for Epithelial-Mesenchymal Transition Process in Diabetic Foot Ulcers via Targeting Interleukin-8

OBJECTIVES

As a complication of diabetes mellitus (DM), one of the leading causes for death and disability for DM patients is diabetic foot ulcers (DFUs). Epithelial to mesenchymal transition (EMT) plays a critical role in wound healing of DFUs. miR-203 is specifically enriched in keratinocytes and has been shown to target interleukin 8 (IL-8), which acts as an activator for the EMT process. In this study, we explored the interaction between miR-203 and IL-8 in DFU rat models and human keratinocyte cells, underlying the mechanism of miR-203's function in DFUs progression.

METHODS

DFU rat models were used to test gene expression in DFU progression. Diabetic keratinocyte cell lines were used to validate in vitro. Wound healing and Transwell assays were applied to evaluate cell migration and invasion abilities. The EMT process was estimated by testing expression of E-cadherin, Vimentin and Slug. The interaction between miR-203 and IL-8 was determined by Luciferase assay.

RESULTS

Our results demonstrated that the wound-healing process had been slowed in DFUs, and the advanced glycation end products (AGEs) and the receptor for advanced glycation end products (RAGEs) in wound tissue were of a higher expression than those in normal rat. miR-203 was increased in skin tissues from DFU rat models, while IL-8 was decreased. Through knock-down of miR-203 in AGE-treated keratinocyte cells, it had been shown that the downregulation of miR-203 could promote cell proliferation and migration, and facilitate the EMT process. Meanwhile, Luciferase assay proved that miR-203 could directly target and inhibit IL-8. The repression of IL-8 could rescue the outcomes brought about by miR-203 inhibition.

CONCLUSIONS

The upregulation of miR-203 in DFU tissues impaired wound healing by the repress EMT process. Specific knock-down of miR-203 could promote wound healing through the reactivation of its target gene IL-8 and the downstream IL-8/AKT pathway.