Cutaneous inflammasome driving ASC / gasdermin-D activation and IL-1ß-secreting macrophages in severe atopic dermatitis.

Atopic dermatitis (AD) is an inflammatory skin disease with intense pruritus, and chronic skin colonization by Staphylococcus aureus. To understand the inflammatory status in AD, we investigated the inflammasome complex, that activates ASC (Apoptosis-associated speck-like protein containing a CARD), caspase-1 and GSDMD (gasdermin-D), and production of IL-1ß and IL-18. We aimed to evaluate the expression of the inflammasome pathway in the skin of adults with AD. Thirty patients with moderate to severe AD and 20 healthy controls were enrolled in the study. We performed the analysis of the inflammasome components NLRP1, NLRP3, AIM-2, IL-1ß, IL-18, Caspase-1, ASC, GSDMD, and CD68 expression (macrophage marker) by immunohistochemistry and immunofluorescence. The main findings included increased expression of NLRP3, NLRP1 and AIM-2 at dermal level of severe AD; augmented IL-18 and IL-1ß expression at epidermis of moderate and severe patients, and in the dermis of severe AD; augmented expression of ASC, caspase-1 and GSDMD in both epidermis and dermis of moderate and severe AD. We detected positive correlation between caspase-1, GSDMD and IL-1ß (epidermis) and caspase-1 (dermis) and AD severity; NLRP3, AIM-2 and IL-1ß, and NLRP3 with IL-18 in the epidermis; ASC, GSDMD and IL-1ß, and NLRP3, AIM-2, caspase-1, and IL-18 in the dermis. We also evidenced the presence of CD68+ macrophages secreting GSDMD, ASC and IL-1ß in moderate and severe AD. Cutaneous macrophages, early detected in moderate AD, have its role in the disease inflammatory mechanisms. Our study indicates a canonical activation pathway of inflammasomes, reinforced by the chronic status of inflammation in AD. The analysis of the inflammasome complex evidenced an imbalance in its regulation, with increased expression of the evaluated components, which is remarkably in severe AD, emphasizing its relevance as potential disease biomarkers and targets for immunomodulatory interventions.

Supercritical CO2 fluid extract from Stellariae Radix ameliorates 2,4-dinitrochlorobenzene-induced atopic dermatitis by inhibit M1 macrophages polarization via AMPK activation.

Yin chai hu (Radix Stellariae) is a root medicine that is frequently used in Chinese traditional medicine to treat fever and malnutrition. In modern medicine, it has been discovered to have anti-inflammatory, anti-allergic, and anticancer properties. In a previous study, we were able to extract lipids from Stellariae Radix using supercritical CO2 extraction (SRE), and these sterol lipids accounted for up to 88.29% of the extract. However, the impact of SRE on the development of atopic dermatitis (AD) has not yet been investigated. This study investigates the inhibitory effects of SRE on AD development using a 2,4-dinitrochlorobenzene (DNCB)-induced AD mouse model. Treatment with SRE significantly reduced the dermatitis score and histopathological changes compared with the DNCB group. The study found that treatment with SRE resulted in a decrease of pro-inflammatory cytokines TNF-α, CXC-10, IL-12, and IL-1ß in skin lesions. Additionally, immunohistochemical analysis revealed that SRE effectively suppressed M1 macrophage infiltration into the AD lesion. Furthermore, the anti-inflammatory effect of SRE was evaluated in LPS + INF-γ induced bone marrow-derived macrophages (BMDMs) M1 polarization, SRE inhibited the production of TNF-α, CXC-10, IL-12, and IL-1ß and decreased the expression of NLRP3. Additionally, SRE was found to increase p-AMPKT172, but had no effect on total AMPK expression, after administration of the AMPK inhibitor Compound C, the inhibitory effect of SRE on M1 macrophages was partially reversed. The results indicate that SRE has an inhibitory effect on AD, making it a potential therapeutic agent for this atopic disorder.

LIGHT signaling through LTßR and HVEM in keratinocytes promotes psoriasis and atopic dermatitis-like skin inflammation.

Psoriasis (PS) and atopic dermatitis (AD) are common skin inflammatory diseases characterized by hyper-responsive keratinocytes. Although, some cytokines have been suggested to be specific for each disease, other cytokines might be central to both diseases. Here, we show that Tumor necrosis factor superfamily member 14 (TNFSF14), known as LIGHT, is required for experimental PS, similar to its requirement in experimental AD. Mice devoid of LIGHT, or deletion of either of its receptors, lymphotoxin ß receptor (LTßR) and herpesvirus entry mediator (HVEM), in keratinocytes, were protected from developing imiquimod-induced psoriatic features, including epidermal thickening and hyperplasia, and expression of PS-related genes. Correspondingly, in single cell RNA-seq analysis of PS patient biopsies, LTßR transcripts were found strongly expressed with HVEM in keratinocytes, and LIGHT was upregulated in T cells. Similar transcript expression profiles were also seen in AD biopsies, and LTßR deletion in keratinocytes also protected mice from allergen-induced AD features. Moreover, in vitro, LIGHT upregulated a broad spectrum of genes in human keratinocytes that are clinical features of both PS and AD skin lesions. Our data suggest that agents blocking LIGHT activity might be useful for therapeutic intervention in PS as well as in AD.

Progressive accumulation of hyperinflammatory NKG2Dlow NK cells in early childhood severe atopic dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease that often precedes the development of food allergy, asthma, and allergic rhinitis. The prevailing paradigm holds that a reduced frequency and function of natural killer (NK) cell contributes to AD pathogenesis, yet the underlying mechanisms and contributions of NK cells to allergic comorbidities remain ill-defined. Here, analysis of circulating NK cells in a longitudinal early life cohort of children with AD revealed a progressive accumulation of NK cells with low expression of the activating receptor NKG2D, which was linked to more severe AD and sensitivity to allergens. This was most notable in children co-sensitized to food and aeroallergens, a risk factor for development of asthma. Individual-level longitudinal analysis in a subset of children revealed coincident reduction of NKG2D on NK cells with acquired or persistent sensitization, and this was associated with impaired skin barrier function assessed by transepidermal water loss. Low expression of NKG2D on NK cells was paradoxically associated with depressed cytolytic function but exaggerated release of the proinflammatory cytokine tumor necrosis factor-α. These observations provide important insights into a potential mechanism underlying the development of allergic comorbidity in early life in children with AD, which involves altered NK cell functional responses, and define an endotype of severe AD.

Single-cell transcriptomics identifies the differentiation trajectory from inflammatory monocytes to pro-resolving macrophages in a mouse skin allergy model.

Both monocytes and macrophages are heterogeneous populations. It was traditionally understood that Ly6Chi classical (inflammatory) monocytes differentiate into pro-inflammatory Ly6Chi macrophages. Accumulating evidence has suggested that Ly6Chi classical monocytes can also differentiate into Ly6Clo pro-resolving macrophages under certain conditions, while their differentiation trajectory remains to be fully elucidated. The present study with scRNA-seq and flow cytometric analyses reveals that Ly6ChiPD-L2lo classical monocytes recruited to the allergic skin lesion sequentially differentiate into Ly6CloPD-L2hi pro-resolving macrophages, via intermediate Ly6ChiPD-L2hi macrophages but not Ly6Clo non-classical monocytes, in an IL-4 receptor-dependent manner. Along the differentiation, classical monocyte-derived macrophages display anti-inflammatory signatures followed by metabolic rewiring concordant with their ability to phagocytose apoptotic neutrophils and allergens, therefore contributing to the resolution of inflammation. The failure in the generation of these pro-resolving macrophages drives the IL-1α-mediated cycle of inflammation with abscess-like accumulation of necrotic neutrophils. Thus, we clarify the stepwise differentiation trajectory from Ly6Chi classical monocytes toward Ly6Clo pro-resolving macrophages that restrain neutrophilic aggravation of skin allergic inflammation.

TRPV1 Channel in Human Eosinophils: Functional Expression and Inflammatory Modulation.

The transient receptor potential vanilloid 1 (TRPV1) is a non-selective cation channel expressed on sensory neurons and immune cells. We hypothesize that TRPV1 plays a role in human eosinophil function and is modulated by inflammatory conditions. TRPV1 expression on human eosinophils was examined by qPCR, flow cytometry, and immunohistochemistry, respectively. TRPV1 functionality was analyzed by investigating calcium flux, apoptosis, modulation by cytokines and acidic pH, and CD69 externalization using flow cytometry. Activation of TRPV1 induced calcium influx and prolonged survival. Although eosinophils were not directly activated by TRPV1 agonists, activation by IL-3 or GM-CSF was mainly restricted to TRPV1-positive eosinophils. TRPV1 surface content was increased by acidic pH, IL-3, IL-31, IL-33, TSLP, TNF-α, BDNF, and NGF-ß. Interestingly, TRPV1 was also expressed by eosinophils located in proximity to peripheral nerves in atopic dermatitis (AD) skin. In conclusion, eosinophils express functional TRPV1 channels which are increased by extracellular acidification and AD-related cytokines. Since eosinophils also express TRPV1 in AD skin, our results indicate an important role of TRPV1 for neuroimmune interaction mechanisms in itchy, inflammatory skin diseases, like AD.

Clinical features and biomarker differences of severe intrinsic and extrinsic atopic dermatitis.

OBJECTIVES: Atopic dermatitis (AD) can be classified into intrinsic AD(IAD) and extrinsic AD(EAD). However, the differences in clinical features and pathogenesis between these two subtypes of AD are currently unclear. This study aimed to analyse the differences in clinical features and peripheral blood biomarkers between Chinese patients with severe IAD and EAD in order to elucidate the physiopathogenesis of AD. MATERIALS AND METHODS: A total of 316 hospitalised patients definitively diagnosed with severe AD were included in this study. There were 72 cases of severe IAD and 244 cases of severe EAD. The clinical features of the patients were recorded in details. Serum total IgE, IgA, IgG, IgM, complementC3/C4, peripheral blood cell counts, lactate dehydrogenase (LDH), C-reactive protein (CRP), erythrocyte sedimentation rate (ESR), IL-2R, IL-6, IL-8, and TNF-α in AD patients and 60 age-matched healthy controls were analysed. IAD and EAD had similar severity/Scoring Atopic Dermatitis (SCORAD) scores. RESULTS: Compared with healthy controls, IAD patients had significantly higher total IgE, eosinophils, monocytes, LDH, CRP, IL-2R, IL-6, IL-8 and TNF-α, and lower IgM and C4. EAD patients had significantly higher total IgE, IgA, eosinophils, white blood cell (WBC) counts, neutrophils, monocytes, basophils, LDH, CRP, IL-2R, IL-6, IL-8, TNF-α and lower IgM than healthy controls. IAD patients had a higher percentage of rural/urban living and female/male, a shorter course of disease and lower total IgE, eosinophils, WBC counts, neutrophils, monocytes, basophils, LDH, IgG and C4 than EAD patients. SCORAD scores, eosinophils, LDH expression levels increased with total IgE uniquely in patients with EAD. CONCLUSIONS: IAD and EAD exhibit specific clinical features and molecular changes. IAD has a more complex physiopathogenesis, and deserves further investigation.

Genomic Profiling of the Overlap Phenotype between Psoriasis and Atopic Dermatitis.

Clinical overlaps between psoriasis and atopic dermatitis (AD) are sometimes undiscernible, and there is no consensus on whether to treat the overlap phenotype as psoriasis or AD. We enrolled 41 patients diagnosed with either psoriasis or AD and clinically re-stratified them into classic psoriasis (n = 11), classic AD (n = 13), and the overlap phenotype between psoriasis and AD (n = 17). We compared the gene expression profiles of lesional and nonlesional skin biopsy tissues and the proteomic profiles of blood samples among the three comparison groups. Global mRNA expression and T-cell subset cytokine expression in the skin and protein biomarker elevation in the blood of the overlap phenotype were consistent with the profiles of psoriasis and different from the profiles of AD. Unsupervised k-means clustering indicated that the best number of distinct clusters for the total population of the three comparison groups was two, and the two clusters of psoriasis and AD were differentiated by gene expression. Our study suggests that the clinical overlap phenotype between psoriasis and AD has dominant molecular features of psoriasis, and genomic biomarkers can differentiate psoriasis and AD at molecular levels in patients with a spectrum of psoriasis and AD.

Dictamnine Ameliorates DNFB-Induced Atopic Dermatitis Like Skin Lesions in Mice by Inhibiting M1 Macrophage Polarization and Promoting Autophagy.

Autophagy and M1 macrophage polarization play important roles in the regulation of inflammation in atopic dermatitis (AD). Dictamnine is one of the main ingredients in Cortex Dictamni, a widely used traditional Chinese medicine for the treatment of dermatitis. In the present study, we investigated the anti-inflammatory effects of dictamnine on AD like skin lesions and M1 macrophage polarization. A 2,4-dinitrofluorobenzene (DNFB) triggered AD like skin lesions models in mice was established to identify the ameliorative effects of dictamnine on AD in vivo. In addition, an M1 macrophage polarization model was co-stimulated by lipopolysaccharide (LPS) and interferon-γ (IFN-γ) using phorbol myristate acetate (PMA) differentiated THP-1 cells, to investigate the effect of dictamnine on promoting autophagy and inhibiting inflammatory factor release. Dictamnine suppressed DNFB-induced skin inflammation by inhibiting M1 macrophage polarization, up-regulating the expression of microtubule-associated protein 1A/1B-light chain 3 (LC3) expression, and promoting macrophage autophagy at inflammatory sites. Dictamnine also could reduce the release of interleukin-1ß (IL-1ß), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), monocyte chemotactic protein-1 (MCP-1), and interleukin-8 (IL-8), and down-regulate the mRNA expression of these genes in LPS-IFN-γ triggered M1 polarized macrophages. Dictamnine ameliorates AD like skin lesions by inhibiting M1 macrophage polarization and promoting autophagy. Hence, dictamnine is expected to be a potential therapeutic candidate for AD.

Cav3.2 T-Type Calcium Channel Mediates Acute Itch and Contributes to Chronic Itch and Inflammation in Experimental Atopic Dermatitis.

Voltage-gated calcium channels regulate neuronal excitability. The Cav3.2 isoform of the T-type voltage-activated calcium channel is expressed in sensory neurons and is implicated in pain transmission. However, its role in itch remains unclear. In this study, we demonstrated that Cav3.2 is expressed by mechanosensory and peptidergic subsets of mouse dorsal root ganglion neurons and colocalized with TRPV1 and receptors for type 2 cytokines. Cav3.2-positive neurons innervate human skin. A deficiency of Cav3.2 reduces histamine, IL-4/IL-13, and TSLP-induced itch in mice. Cav3.2 channels were upregulated in the dorsal root ganglia of an atopic dermatitis (AD)-like mouse model and mediated neuronal excitability. Genetic knockout of Cav3.2 or T-type calcium channel blocker mibefradil treatment reduced spontaneous and mechanically induced scratching behaviors and skin inflammation in an AD-like mouse model. Substance P and vasoactive intestinal polypeptide levels were increased in the trigeminal ganglia from AD-like mouse model, and genetic ablation or pharmacological inhibition of Cav3.2 reduced their gene expression. Cav3.2 knockout also attenuated the pathologic changes in ex vivo skin explants cocultured with trigeminal ganglia neurons from AD-induced mice. Our study identifies the role of Cav3.2 in both histaminergic and nonhistaminergic acute itch. Cav3.2 channel also contributes to AD-related chronic itch and neuroinflammation.

Development of IL-17A inhibitor-induced atopic dermatitis-like rash in psoriasis patients: Insights into immune shift.

Cases of atopic dermatitis (AD)-like rash induced by IL-17A inhibitor secukinumab treatment (SI-AD) have been recently reported in psoriasis patients. To identify immune and inflammatory factors expression in SI-AD. A panel of 15 immune and inflammatory factors in peripheral blood samples from various groups, including patients with patients with SI-AD, psoriasis with secukinumab (S-stable), advanced psoriasis patients (Advanced) and healthy controls (HC). Interleukin-10 (IL-10), IL-4 and IL-17A were detected in skin tissue biopsy samples by immunohistochemistry and real-time quantitative polymerase chain reaction. The immunoglobulin E levels in the SI-AD patients exceeded normal values. The IL-10 levels in SI-AD patients were higher than those in S-stable patients, advanced patients and HC. The IL-4 levels in SI-AD patients were higher than that in S-stable patients and HC. The IL-17A levels in SI-AD patients were higher than those in advanced psoriasis patients and HC, but no significant differences were observed between SI-AD patients and S-stable patients. IL-10 and IL-4 levels were higher in AD-like rashes than in healthy skin, while IL-17A did not differ significantly between the two. Upon discontinuing secukinumab, and switching to oral cyclosporine, antihistamines, Janus kinase 1 inhibitor and topical glucocorticoids, SI-AD patients experienced significant improvement in their skin lesions. Upon reexamination, all 15 immune and inflammatory factors returned to normal levels. Immune shift from Th17 towards Th2 may occur in SI-AD, as indicated by abnormal expression of multiple immune and inflammatory factors observed in peripheral blood and skin tissues.

Sodium Butyrate Ameliorates Atopic Dermatitis-Induced Inflammation by Inhibiting HDAC3-Mediated STAT1 and NF-κB Pathway.

A topic dermatitis (AD) is a common chronic and recurrent skin disorder. The protective effects of sodium butyrate (NaB), a metabolite of short-chain fatty acid breakdown by the gut microbiota, have been widely reported in numerous inflammatory diseases. However, the effect of NaB treatment alone on AD has not been reported. In the current study, AD was induced in BALB/c mice with 2,4-dinitrochlorobenzene (DNCB) for 28 days with NaB (200 mg/kg) treatment by gavage. NaB attenuated AD-induced skin bleeding, scarring, dryness, abrasions and erosions. In addition, NaB inhibited inflammatory cells infiltration and attenuated the expression of inflammatory cytokines and chemokines. Mechanistically, NaB reduced histone deacetylase 3 (HDAC3) expression and NF-κB p65 nuclear translocation by increasing the lysine acetylation levels of STAT1 and NF-κB p65 in AD. Taken together, our study suggests that NaB inhibits inflammatory mediators and ameliorates AD by inhibiting HDAC3 expression, thereby upregulating STAT1 and NF-κB p65 lysine acetylation levels and reducing NF-κB p65 nuclear translocation. Therefore, this study provides a new theoretical basis for NaB in the treatment of AD.

Potential inhibition of 12-O-tetradecanoylphorbol-13-acetate-induced inflammation, hyperproliferation, and hyperplasiogenic responses by celecoxib in mouse skin.

PURPOSE: Skin exposure to noxious agents leads to cutaneous lesion marked by an increase in inflammation, cellular proliferation, and hyperplasiogenic reactions. Studies have demonstrated that these damages breach the skin integrity resulting in the aetiology of various cutaneous disorders like atopic dermatitis, eczema, psoriasis, and development of non-melanoma skin cancer. Celecoxib, a cyclooxygenase-2 (COX-2) inhibitor, is an effective treatment for a variety of inflammatory diseases. Its importance in the therapy of skin problems, however, remains under appreciated. METHODS: We tested efficacy of topically applied celecoxib in mitigating skin inflammation, cellular proliferation, and hyperplasia induced by the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) in Swiss albino mice. RESULTS: Celecoxib (5 and 10 µmol) markedly reduced TPA (10 nmol) induced prostaglandin E2 (PGE2) production, oedema formation, myeloperoxidase (MPO) activity, and levels of pro-inflammatory cytokines such as tumour necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1ß), and interleukin-6 (IL-6). It also resulted in a considerable decrease in ornithine decarboxylase (ODC) activity and the incorporation of [3H]-thymidine into DNA. In addition, there was a significant reduction in histoarchitectural abnormalities such as epidermal thickness, number of epidermal cell layers, neutrophil infiltration, intercellular oedema, and vasodilation. CONCLUSION: Our results demonstrate that topical celecoxib can reduce the inflammation, hyperproliferation, and hyperplasiogenic events of skin insults suggesting that it may prove to be a valuable management option for cutaneous lesion and associated illnesses such as atopic dermatitis, eczema, and psoriasis, as well as the emergence of non-melanoma cancer.

Macrophage autophagy deficiency-induced CEBPB accumulation alleviates atopic dermatitis via impairing M2 polarization.

Macroautophagy/autophagy plays a pivotal role in immune regulation. Its significance is evident in modulation of immune cell differentiation and maturation, physiologically and pathologically. Here, we investigate the role of macrophage autophagy on the development of atopic dermatitis (AD). By employing an MC903-induced AD mice model, we observe reduced cutaneous inflammation in macrophage Atg5 cKO mice compared with WT mice. Notably, there is a decreased infiltration of M2 macrophages in lesional skin from Atg5 cKO mice. Furthermore, impaired STAT6 phosphorylation and diminished expression of M2 markers are detected in autophagy-deficient macrophages. Our mechanistic exploration reveals that CEBPB drives the transcription of SOCS1/3 and SQSTM1/p62-mediated autophagy degrades CEBPB normally. Autophagy deficiency leads to CEBPB accumulation, and further promotes the expression of SOCS1/3. This process inhibits JAK1-STAT6 pathway activation and M2 marker expression. Together, our study indicates that autophagy is required for M2 activation and macrophage autophagy may be a promising target for AD intervention.

Macrocystis pyrifera Lipids Reduce Cytokine-Induced Pro-Inflammatory Signalling and Barrier Dysfunction in Human Keratinocyte Models.

Atopic dermatitis is a chronic condition where epidermal barrier dysfunction and cytokine production by infiltrating immune cells exacerbate skin inflammation and damage. A total lipid extract from Macrocystis pyrifera, a brown seaweed, was previously reported to suppress inflammatory responses in monocytes. Here, treatment of human HaCaT keratinocytes with M. pyrifera lipids inhibited tumour necrosis factor (TNF)-α induced TNF receptor-associated factor 2 and monocyte chemoattractant protein (MCP)-1 protein production. HaCaT cells stimulated with TNF-α, interleukin (IL)-4, and IL-13 showed loss of claudin-1 tight junctions, but little improvement was observed following lipid pre-treatment. Three-dimensional cultures of HaCaT cells differentiated at the air-liquid interface showed increased MCP-1 production, loss of claudin-1 tight junctions, and trans-epidermal leakage with TNF-α, IL-4, and IL-13 stimulation, with all parameters reduced by lipid pre-treatment. These findings suggest that M. pyrifera lipids have anti-inflammatory and barrier-protective effects on keratinocytes, which may be beneficial for the treatment of atopic dermatitis or other skin conditions.

Atopic Dermatitis: Molecular Alterations between Lesional and Non-Lesional Skin Determined Noninvasively by In Vivo Confocal Raman Microspectroscopy.

Atopic dermatitis (AD)/atopic eczema is a chronic relapsing inflammatory skin disease affecting nearly 14% of the adult population. An important pathogenetic pillar in AD is the disrupted skin barrier function (SBF). The atopic stratum corneum (SC) has been examined using several methods, including Raman microspectroscopy, yet so far, there is no depth-dependent analysis over the entire SC thickness. Therefore, we recruited 21 AD patients (9 female, 12 male) and compared the lesional (LAS) with non-lesional atopic skin (nLAS) in vivo with confocal Raman microspectroscopy. Our results demonstrated decreased total intercellular lipid and carotenoid concentrations, as well as a shift towards decreased orthorhombic lateral lipid organisation in LAS. Further, we observed a lower concentration of natural moisturising factor (NMF) and a trend towards increased strongly bound and decreased weakly bound water in LAS. Finally, LAS showed an altered secondary and tertiary keratin structure, demonstrating a more folded keratin state than nLAS. The obtained results are discussed in comparison with healthy skin and yield detailed insights into the atopic SC structure. LAS clearly shows molecular alterations at certain SC depths compared with nLAS which imply a reduced SBF. A thorough understanding of these alterations provides useful information on the aetiology of AD and for the development/control of targeted topical therapies.

Inhibition of gasdermin D (GSDMD) as a promising therapeutic approach for atopic dermatitis.

Atopic dermatitis (AD) is a chronic inflammatory skin disease characterized by pruritus, erythema, and skin barrier dysfunction. Gasdermin D (GSDMD) is the key executioner of an inflammatory cell death mechanism known as pyroptosis. However, the role of GSDMD in the pathogenesis of AD remains unclear. Through the analysis of publicly available Gene Expression Omnibus (GEO) datasets, we observed an upregulation of Gsdmd mRNA in the skin tissue of AD patients. Moreover, we delved into the impact of GSDMD deletion and inhibition on AD-like skin lesions using a mouse model induced by the topical application of oxazolone (Oxa). We found that mice lacking GSDMD exhibited relieved AD signs and symptoms in terms of reduced skin thickness, scarring and scratching behavior compared to wild-type mice after induction of AD-like skin lesions. This was associated with decreased infiltration of inflammatory cells, reduced epidermal thickness, and decreased serum levels of IgE and IL-4. Western blot analysis further revealed decreased GSDMD cleavage in the skin of GSDMD knockout mice, and reduced expression of IL-1ß and IL-18. Inhibition of GSDMD using the pharmacological agent disulfiram or the herbal compound matrine significantly attenuated the symptoms of AD-like skin lesions in wild-type mice, GSDMD cleavage and pro-inflammatory cytokines were reduced as well. Our results suggest that GSDMD-mediated pyroptosis plays a critical role in the development of AD-like skin lesions, and targeting GSDMD may be a promising therapeutic strategy for AD.

Canine amniotic membrane-derived mesenchymal stem cells ameliorate atopic dermatitis through regeneration and immunomodulation.

Mesenchymal stem cells (MSCs) are a promising tool for treating immune disorders. However, the immunomodulatory effects of canine MSCs compared with other commercialized biologics for treating immune disorders have not been well studied. In this study we investigated the characteristics and immunomodulatory effects of canine amnion membrane (cAM)-MSCs. We examined gene expression of immune modulation and T lymphocytes from activated canine peripheral blood mononuclear cell (PBMC) proliferation. As a result, we confirmed that cAM-MSCs upregulated immune modulation genes (TGF-ß1, IDO1 and PTGES2) and suppressed the proliferation capacity of T cells. Moreover, we confirmed the therapeutic effect of cAM-MSCs compared with oclacitinib (OCL), the most commonly used Janus kinase (JAK) inhibitor, as a treatment for canine atopic dermatitis (AD) using a mouse AD model. As a result, we confirmed that cAM-MSCs with PBS treatment groups (passage 4, 6 and 8) compared with PBS only (PBS) though scores of dermatologic signs, tissue pathologic changes and inflammatory cytokines were significantly reduced. In particular, cAM-MSCs were more effective than OCL in the recovery of wound dysfunction, regulation of mast cell activity and expression level of immune modulation protein. Interestingly, subcutaneous injection of cAM-MSCs induced weight recovery, but oral administration of oclacitinib induced weight loss as a side effect. In conclusion, this study suggests that cAM-MSCs can be developed as a safe canine treatment for atopic dermatitis without side effects through effective regeneration and immunomodulation.

Increased Interleukin-36ß Expression Promotes Angiogenesis in Japanese Atopic Dermatitis.

While atopic dermatitis (AD) is considered as a T helper 2 (Th2)-centered disease, an increase in other types of inflammatory cytokines is also noted in AD and they may also contribute to the development of the disease. Recently, the efficacy of an anti-IL-36 receptor antibody in AD was demonstrated in a clinical trial. Although there have been several reports on IL-36α and IL-36γ expression and function in AD, IL-36ß has been barely studied. In this report, we examined IL-36ß expression and function using clinical samples of AD and the epidermal keratinocyte cell line, HaCaT cells. We demonstrated that IL-36ß expression in epidermal keratinocytes was increased in AD lesional skin compared to healthy skin. IL-36ß promoted vascular endothelial growth factor A production in HaCaT keratinocytes through phosphorylation of extracellular signal-regulated kinases 1 and 2. In addition, IL-36ß up-regulated placental growth factor mRNA expression in HaCaT keratinocytes. IL-36ß expression levels in epidermal keratinocytes were correlated with the number of dermal vessels in AD skin. These results suggest that IL-36ß may play an important role for angiogenesis in lesional skin of AD and that IL-36ß can be a therapeutic target in AD.

Adipose-derived stem cell exosomes for treatment of dupilumab-related facial redness in patients with atopic dermatitis.

BACKGROUND: Dupilumab facial redness (DFR) is a side effect of dupilumab treatment that has only been recently reported. We previously reported on two patients with DFR who were successfully treated with a topical formulation containing human adipose tissue-derived mesenchymal stem cell-derived exosomes (ASCEs). OBJECTIVES: The study aimed to evaluate the efficacy and safety of ASCEs in DFR. PARTICIPANTS AND METHODS: We performed 12-week prospective study at single center. Twenty adult atopic dermatitis patients diagnosed with DFR were enrolled. They were treated with a topical application of the exosome formulation every week for five consecutive weeks. RESULTS: After exosome treatment, both the average investigator global assessment score and clinical erythema assessment scale scores decreased. 19 patients (95%) were satisfied with the treatment. Compared to baseline, erythema index at week 4 were decreased by 31, 27, 13, and 25 units on the forehead, chin, right and left cheek respectively. The analysis of stratum corneum samples revealed the expression of IL-1α and human thymic stromal lymphopoietin was suppressed after exosome treatment, whereas filaggrin and vascular endothelial growth factor expression increased. CONCLUSIONS: This study suggests topical formulation containing ASCEs can alleviate DFR by downregulating local inflammation and restoring skin barrier function.