New insights into T cells and their signature cytokines in atopic dermatitis

Evaluation of Artemisia dubia folium extract-mediated immune efficacy through developing a murine model for acute and chronic stages of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a biphasic type of skin inflammation characterized by a predominance of type-2 (TH2) and type-1 (TH1) helper T cell-biased immune responses at the acute and persistent chronic phases, respectively. The present study was aimed to evaluate the efficacy of Artemisia dubia folium extract (ADFE) on AD-like skin lesions through developing a murine model for acute and chronic stages of AD. To induce acute phase AD, the dorsal skin of BALB/c mice was sensitized twice a week with 1% 2, 4-dinitrochlorobenzene (DNCB), followed by challenge (twice) in the following week with 0.2% DNCB. To induce persistent chronic AD, some mice were challenged twice a week for 4 more weeks. After the second challenge, the dorsal skin was exposed to 3% ADFE (five times per week) for 2 weeks (acute phase) or 4 weeks (persistent chronic phase).

RESULTS

The paradigm of TH2 or TH1 predominance at the acute and chronic phase, respectively, was observed in this mouse model. During the acute phase, we observed an increased IL-4/IFN-γ ratio in splenic culture supernatants, an increased IgG1/IgG2a ratio in serum, and elevated serum IgE levels; however, the skew toward TH2 responses was diminished during the chronic stage. Compared with vehicle controls, ADFE reduced the IL-4/IFN-γ and IgG1/IgG2a ratios in acute AD, but both ratios increased during the chronic stage.

CONCLUSIONS

Our results suggest that ADFE concomitantly suppresses the TH2 predominant response in acute AD, as well as the TH1 predominant response in chronic AD. Thus, ADFE is a candidate therapeutic for AD.

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.

Crisaborole loaded nanoemulgel for the mitigation of atopic dermatitis in mice model

OBJECTIVE

The present work aims to formulate nanoemulgel of crisaborole (CB) and evaluate its effectiveness against 2,4-Di-nitrochlorobenzene induced (DNCB) atopic dermatitis (AD) in mice.

SIGNIFICANCE

AD is a chronic inflammation of the skin affecting the quality of life. CB is a topical PDE4 inhibitor marketed as a 2% ointment. It, however, possesses poor aqueous solubility. An o/w nanoemulsion shall exhibit an enhanced therapeutic effect owing to the increased solubility of CB and an augmented skin penetration. The addition of a gelling agent to form a nanoemulgel further provides ease of application to the patients.

METHODS

Nanoemulsion was prepared by aqueous titration method using caproyl PGMC, cremophore EL and propylene glycol as the oil, surfactant, and cosurfactant respectively. The formulations were characterized by their size, zeta potential and polydispersity index (PDI). 1% Carbopol 934 was used as the gelling agent to formulate nanoemulgel comprising of optimized nanoemulsion (NE 9). Ex vivo skin permeation of the CB nanoemulgel was compared with the CB ointment. Its therapeutic effect was evaluated in Balb/c mice.

RESULTS

NE 9 comprised of 7.49% oil, 37.45% Smix (1:3) and water 55.06%. Its particle size, PDI and zeta potential were 15.45 ± 5.265 nm, 0.098 and -17.9 ± 8.00 mV respectively. The nanoemulgel exhibited a 3-fold higher permeation flux as compared to the ointment. In vivo studies demonstrated that the nanoemulgel provided better therapeutic effect than the ointment.

CONCLUSION

We can thereby conclude that nanoemulgel formulation can be a successful drug delivery strategy for enhancing the therapeutic effect of CB.

Evaluation of Leukocytes, B and T Lymphocytes, and expression of CD200 and CD23 on B lymphocytes in Patients with Atopic Dermatitis on Dupilumab Therapy-Pilot Study

BACKGROUND

There are a lot of studies that describe the change in quantity of T cells in patients with atopic dermatitis (AD) compared with healthy subjects. Other components of lymphocytes such as B cells are not examined as well as T cells.

OBJECTIVE

We focus on immunophenotyping of B cells with their subsets (memory, naïve, switched, non-switched) and the expression of CD23 and CD200 markers in patients with AD with and without dupilumab therapy. We also evaluate the count of leukocytes and their subsets, T lymphocytes (CD4⁺, CD8⁺), natural killer (NK) cells, and T regulatory cells.

METHODS

A total of 45 patients suffering from AD were examined: 32 patients without dupilumab treatment (10 men, 22 women, average age 35 years), 13 patients with dupilumab treatment (7 men, 6 women, average age 43.4 years), and 30 subjects as a control group (10 men, 20 women, average age 44.7 years). Immunophenotype was examined by flow cytometry in which monoclonal antibodies with fluorescent molecules were used. We compared the absolute and relative count of leukocytes and their subsets, T lymphocytes (CD4⁺ , CD8⁺), NK cells, T regulatory cells, absolute and relative count of B lymphocytes (memory, naïve, non-switched, switched, transient), and expression of CD23 and CD200 activation markers on B cells and on their subsets in patients with AD and control group. For statistical analysis we used nonparametric Kruskal-Wallis one-factor analysis of variance with post hoc by Dunn's test with Bonferroni modification of significance level.

RESULTS

In patients with AD with and without dupilumab therapy we confirmed the significantly higher count of neutrophils, monocytes, and eosinophils; there was no difference in absolute count of B cells, NK cells and transitional B cells compared with control subjects. We confirmed higher expression of activation marker CD23 on total, memory, naïve, non-switched, and switched B lymphocytes and higher expression of CD200 on total B lymphocytes in both groups of patients with AD compared with controls. In patients without dupilumab therapy we confirmed significantly higher count of relative monocytes, relative eosinophils, and higher expression of CD200 on memory, naïve, and non-switched B lymphocytes compared with controls. In patients with dupilumab therapy we confirmed significantly higher expression of CD200 on switched B lymphocytes, higher count of relative CD4⁺ T lymphocytes, and lower count of absolute CD8⁺ T lymphocytes compared with controls.

CONCLUSION

This pilot study shows higher expression of CD23 on B lymphocytes and on their subsets in patients with AD with and without dupilumab therapy. The higher expression of CD200 on switched B lymphocytes is confirmed only in patients with AD with dupilumab therapy.

Design and characterization of matrix metalloproteinase-responsive hydrogels for the treatment of inflammatory skin diseases

Enzyme-responsive hydrogels, formed by step growth photopolymerization of biscysteine peptide linkers with alkene functionalized polyethylene glycol, provide interesting opportunities as biomaterials and drug delivery systems. In this study, we developed stimuli-responsive, specific, and cytocompatible hydrogels for delivery of anti-inflammatory drugs for the treatment of inflammatory skin diseases. We designed peptide linkers with optimized sensitivity towards matrix metalloproteinases, a family of proteolytic enzymes overexpressed in the extracellular matrix of the skin during inflammation. The peptide linkers were crosslinked with branched 4-arm and 8-arm polyethylene glycols by thiol-norbornene photopolymerization, leading to the formation of a hydrogel network, in which the anti-inflammatory Janus kinase inhibitor tofacitinib citrate was incorporated. The hydrogels were extensively characterized by physical properties, in vitro release studies, cytocompatibility with fibroblasts, and anti-inflammatory efficacy testing in both an atopic dermatitis-like keratinocyte assay and an activated T-cell assay. The drug release was studied after single and multiple-time exposure to matrix metalloproteinase 9 to mimic inflammatory flare-ups. Drug release was found to be triggered by matrix metalloproteinase 9 and to depend on type of crosslinker and of the polyethylene glycol polymer, due to differences in architecture and swelling behavior. Moreover, swollen hydrogels showed elastic properties similar to those of extracellular matrix proteins in the dermis. Cell studies revealed limited cytotoxicity when fibroblasts and keratinocytes were exposed to the hydrogels or their enzymatic cleavage products. Taken together, our results suggest multi-arm polyethylene glycol hydrogels as promising matrix metalloproteinase-responsive drug delivery systems, with potential in the treatment of inflammatory skin disease. STATEMENT OF SIGNIFICANCE: Smart responsive drug delivery systems such as matrix metalloproteinase-responsive hydrogels are excellent candidates for the treatment of inflammatory skin diseases including psoriasis. Their release profile can be optimized to correspond to the patient's individual disease state by tuning formulation parameters and disease-related stimuli, providing personalized treatment solutions. However, insufficient cross-linking efficiency, low matrix metalloproteinase sensitivity, and undesirable drug release kinetics remain major challenges in the development of such drug delivery systems. In this study, we address shortcomings of previous work by designing peptide linkers with optimized sensitivity towards matrix metalloproteinases and high cross-linking efficiencies. We further provide a proof-of-concept for the usability of the hydrogels in inflammatory skin conditions by employing a drug release set-up simulating inflammatory flare-ups.

Therapeutic potential of adipose tissue-derivatives in modern dermatology

Stem cell-mediated therapies in combination with biomaterial and growth factor-based approaches in regenerative medicine are rapidly evolving with increasing application beyond the dermatologic field. Adipose-derived stem cells (ADSCs) are the more frequently used adult stem cells due to their abundance and easy access. In the case of volumetric defects, adipose tissue can take the shape of defects, restoring the volume and enhancing the regeneration of receiving tissue. When regenerative purposes prevail on volume restoration, the stromal vascular fraction (SVF) rich in staminal cells, purified mesenchymal stem cells (MSCs) or their cell-free derivatives grafting are favoured. The therapeutic efficacy of acellular approaches is explained by the fact that a significant part of the natural propensity of stem cells to repair damaged tissue is ascribable to their secretory activity that combines mitogenic factors, cytokines, chemokines and extracellular matrix components. Therefore, the secretome's ability to modulate multiple targets simultaneously demonstrated preclinical and clinical efficacy in reversing pathological mechanisms of complex conditions such atopic dermatitis (AD), vitiligo, psoriasis, acne and Lichen sclerosus (LS), non-resolving wounds and alopecia. This review analysing both in vivo and in vitro models gives an overview of the clinical relevance of adipose tissue-derivatives such as autologous fat graft, stromal vascular fraction, purified stem cells and secretome for skin disorders application. Finally, we highlighted the major disease-specific limitations and the future perspective in this field.

Effect of Sopoongsan on Skin Inflammation and Hyperlocomotion in Socially Isolated Mice with Atopic Dermatitis

Psychological stress is a major exacerbating factor of atopic dermatitis (AD), a chronic inflammatory skin disease. Sopoongsan (SPS), a traditional herbal formula, has been indicated for the treatment of various skin disorders, including AD. This study investigated the effects of SPS on a 2,4-dinitrochlorobenzene- (DNCB-) induced AD mice model exposed to social isolation (SI) stress. The severity of the AD symptoms and behavioral abnormalities was evaluated. SPS reduced the clinical skin score as evaluated with the SCORing Atopic Dermatitis (SCORAD) index and suppressed the cutaneous infiltration of T-lymphocyte cells, mast cells, and eosinophils in SI-AD mice. The SPS treatment decreased the total distance and mean speed and increased resting time in the open field test (OFT) for these mice. In addition, the time spent in the social zone in the social interaction test also improved when SPS treatment was given. The levels of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in the prefrontal cortex (PFC) in the SI-AD mice were reduced by the oral administration of SPS. HaCaT and BV2 cells were used for the in vitro experiments. The pretreatment with SPS reduced the protein levels of the thymus and activation-regulated chemokine (TARC) and macrophage-derived chemokine (MDC) in the HaCaT cells stimulated with TNF-α and interferon-gamma (IFN-γ) (TI). SPS also suppressed TNF-α and IL-6 secretion in lipopolysaccharide- (LPS-) stimulated BV2 cells. These results imply that SPS could be a promising candidate for the treatment of AD in patients under stress conditions and at risk of exacerbation.

Targeting therapeutic approaches and highlighting the potential role of nanotechnology in atopic dermatitis

Atopic dermatitis is a chronic as well as widespread skin disease which has significant influence on the life attributes of affected people and their families. Systemic immunosuppressive drugs can be utilised for effective care of disease, although they are often prescribed for rigorous disruption or disease that is complicated to manage. Therefore, topical applications of corticosteroids are considered the primary pharmacologic therapies for atopic dermatitis, and research recommends that these medications might be helpful in preventing disease flare-ups. However, topical medicine administration to deeper layers of skin is challenging because of the skin anatomic barrier that restricts deeper drug permeation, and also due to barrier function abnormalities in atopic dermatitis skin, which might result in systemic drug absorption, provoking systemic consequences. Hence, effective management of atopic dermatitis needs new, effective, safe and targeted treatments. Therefore, nanotechnology-based topical therapeutics have attracted much interest nowadays because of their tendency to increase drug diffusion and bioavailability along with enormous drug targeting potential to affected cells, and, thereby, reducing the adverse effects of medications. In this review, we mention different symptoms of atopic dermatitis, and provide an overview of the different triggering factors causing atopic dermatitis, with emphasis on its epidemiology, pathophysiology, clinical features and diagnostic, and preventive measures. This review discusses existing therapeutics for treating atopic dermatitis, and the newer approaches as well as the current classical pharmacotherapy of atopic dermatitis against new nanoparticle skin delivery systems. This review has also briefly summarised the recent patents and clinical status of therapeutic modalities for atopic dermatitis.

Peucedanum japonicum Thunberg alleviates atopic dermatitis-like inflammation via STAT/MAPK signaling pathways in vivo and in vitro

Atopic dermatitis (AD) is a chronic, pruritic inflammatory skin disorder that exhibits clinical relapse. The disruption of the skin barrier increases the symptoms of AD, which is accompanied by a reduction in skin integrity. As an immune barrier, the skin plays a crucial role in regulating the inflammatory responses in AD. In this study, we used murine atopic dermatitis model using 2,4-dinitrochlorobenzen (DNCB), which is one of haptens to disrupt the skin barrier and generate the inflammation. As the small molecule, DNCB is easily penetrate the epidermis and binds to tissue proteins provoking immune responses. We evaluated the effects of an aqueous extract of Peucedanum japonicum Thunberg (PJT) in an experimental model of AD by measuring the mRNA and protein expression of cytokines and their related biomarkers. We examined the dorsal skin lesions, transepidermal water loss (TEWL), scratching behavior, expression of molecules related to skin barrier integrity, and histological changes in a murine model of DNCB- induced AD. We found out the down-regulatory effects of PJT on the AD-like symptoms or inflammatory dorsal lesions. For in vitro study, we used a mixture of tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in human keratinocytes. The protein and mRNA expressions of skin barrier molecules and inflammatory markers were measured with western blotting and qRT-PCR assays, respectively. As a result, PJT alleviated the AD-like symptoms, and suppressed the inflammation caused by a TNF-α and IFN-γ in human keratinocytes. The regulatory effects of PJT appeared to be mediated via the mitogen-activated protein kinase (MAPK) and signal transducers and activators of transcription (STAT) signaling pathways both in vivo and in vitro. Altogether, the results indicated that PJT could serve as a promising therapeutic candidate for suppressing AD by inhibiting inflammation and improving the integrity of the skin barrier.

Picrasma quassioides (D.DON) Benn. Ethanolic Extract Improves Atopic Dermatitis and Hyperactivity Disorder in DNCB-Treated BALB/c Mice

Atopic dermatitis (AD) is a chronic inflammatory skin disorder that can be associated with psychiatric disorders. Picrasma quassioides (D.Don) Benn (Gomokpi, GMP), a traditional medicinal herb, has been used to treat skin diseases, including AD. The current study examined the effects of an ethanolic extract of GMP on 2,4-dinitrochlorobenzene (DNCB)-induced AD mice. The severity of skin symptoms and behavioral changes in AD mice were evaluated. GMP alleviated the AD-like skin inflammation and hyperlocomotion activity in DNCB-treated BALB/c mice. The effects of GMP behavioral abnormalities might occur by inhibiting TNF-α production in the PFC. GMP suppressed the production of TARC (Th2 chemokine) in TI-stimulated HaCaT keratinocytes. Moreover, GMP also exerted immunosuppressive effects by reducing TNF-α production in LPS-stimulated Raw264.7 macrophages, IL-17 expression in PI-stimulated EL4 cells, and VEGF secretion in SP-stimulated HMC-1 cells. These findings suggest that GMP could be useful for treating AD by modulating inflammatory responses and comorbid behavioral changes.

New Biologics for the Treatment of Atopic Dermatitis: Analysis of Efficacy, Safety, and Paradoxical Atopic Dermatitis Acceleration

Atopic dermatitis (AD) is a chronic, inflammatory skin disease with an eczematous rash and itching. Due to undesired adverse effects of traditional systemic treatment, there is still an unmet need for safe and effective long-term therapy for refractory AD. As our understanding of the pathogenesis underlying AD grows, novel treatments targeting specific molecules have been developed. Here, we discuss the efficacy and safety profiles of these drugs in recent clinical trials. Among their adverse effects, of particular note is AD acceleration. Although there is still debate about whether certain adverse reactions can be said to be paradoxical adverse events (PAEs), a wide range of PAEs have been reported during biological treatment for chronic immune-mediated diseases. Close surveillance of novel biologics is crucial to detect new undescribed paradoxical reactions and to shed light on the convoluted pathogenesis of AD.

Evaluation of the cutaneous expression of IL-17, IL-22, IL-31, and their receptors in canine atopic dermatitis

Interleukins (IL)-17, IL-22, and IL-31 play roles in human atopic dermatitis (AD), but scant information is available on canine AD. Histopathological assessment for interleukin expression is a challenge due to a lack of canine specific antibodies. To evaluate the mRNA and protein expression of IL-17 and IL-22, and mRNA expression of IL-31 and their receptors in the skin of healthy and atopic dogs, seventeen atopic (10 with and 7 without an active infection) and 13 healthy privately owned dogs were sampled. RNAscope® In situ hybridization (ISH) for IL-17, IL-22, IL-31, and their receptors was performed on archived canine skin samples. Simultaneously, indirect immunofluorescence (IIF) was performed for IL-17 and IL-22. RNAscope® ISH probes were validated by RT-PCR and RNAscope® ISH on cytospin preparations of peripheral blood mononuclear cells from atopic dogs. IL-17, IL-22, IL-31, and their receptors were successfully detected by RNAscope® ISH and by IIF (IL-17 and IL-22) in both atopic and healthy canine skin. There was no significant difference in the expression of interleukins and their receptors between healthy and atopic skin with or without active infection. Data from both methodologies were similar. The role and the relationship among those proteins in atopic skin is unclear from this study results. Data from IIF and ISH were overlapping and support each other. Fresh skin samples taken at different times during the development of atopic dermatitis might better assess the role that interleukins and their receptors play in AD.

Derma-Hc, a New Developed Herbal Formula, Ameliorates Cutaneous Lichenification in Atopic Dermatitis

Atopic dermatitis (AD) is a chronic cutaneous disorder that is characterized by severe eczematous inflammation, swelling, and lichenification. Activation of T helper (Th)-22 cells by allergens leads to epidermal hyperplasia with hyperkeratosis at the chronic phase of AD. Derma-Hc is composed of five natural herbs with anti-AD effects, such as Astragalus membranaceus BUNGE, Schizonepeta tenuifolia Briq., Cryptotympana pustulata Fabr., Angelica sinensis Diels, Arctium lappa L. In this study, the ameliorative effect of Derma-Hc on cutaneous lichenification in 2,4-dinitrochlorobenzne (DNCB)-induced AD was investigated. The dorsal skin of mice was sensitized with DNCB to induce AD-like skin lesions. The dermatitis score and frequency of scratching were evaluated. Thickness of epidermis and dermis was measured by staining with H&E. In addition, infiltration of the mast cell was observed by staining with toluidine blue. Then, desmosomal cadherin, DSC1 was examined by immunofluorescence. Pathological mechanisms involved in lichenification were analyzed in AD-like skin lesions and TNF-α + IFN-γ-treated with human keratinocytes including keratinocyte differentiation genes and JAK1-STAT3 signaling pathway with IL-22 by RT-PCR and western blotting. Topical treatment of Derma-Hc improved AD-like symptoms such as dryness, edema and lichenefication and decreased the number of scratches. Histopathological analysis demonstrated that Derma-Hc significantly inhibited epidermal hyperplasia, hyperkeratosis, and mast cells infiltration. In addition, the level of DSC1 was highly expressed in the epidermis by Derma-Hc. Moreover, mRNA expression level of FLG, an epidermal differentiation complex gene, was recovered by Derma-Hc treatment. KLK5 and KLK7 were markedly reduced to normalize keratinocyte differentiation in dorsal skin tissues and human keratinocytes. On the other hand, Derma-Hc restored expression level of SPINK5. In addition, Derma-Hc inhibited IL-22 via the blockade of JAK1-STAT3 signal pathway. Taken together, Derma-Hc, a natural herbal formula, regulated keratinocyte differentiation and inhibited epidermal hyperplasia with hyperkeratosis. Therefore, Derma-Hc could be a promising candidate for treating chronic AD through modulating signaling of IL-22-associated skin lichenification.

Distinct clinical features and serum cytokine pattern of elderly atopic dermatitis in China

BACKGROUND

Elderly atopic dermatitis (AD) is a newly defined subtype of AD stratified by age-related clinical pictures.

OBJECTIVES

To analyse the clinical features and molecular profile of elderly AD patients in China, comparing with infantile, childhood and adolescent/adult AD.

METHODS

A total of 1312 patients diagnosed by Hanifin and Rajka diagnostic criteria of AD from Huashan Hospital, Shanghai, China, were divided into four groups by age (2-18, 19-40, 41-60 and >60 years), and clinical features were evaluated by questionnaire and physical examination. Serum total IgE, eosinophil counts and various cytokines were further analysed in some of the patients and healthy controls.

RESULTS

Elderly AD showed significantly higher male/female ratio and rural/urban ratio than other age groups, and more than half of elderly AD first appeared after 60 years old. Skin lesions of elderly AD were more often seen in the trunk and extensor sites of the extremities. Level of serum IgE and eosinophil counts were significantly lower in elderly AD than those in other age groups. Serum levels of IL-4, TARC, IL-17A, IL-6, IL-22, IL-33 and TSLP were significantly higher in elderly AD patients than those of healthy controls, indicating a mixed Th2/Th17/Th22 inflammation.

CONCLUSIONS

Elderly AD demonstrated unique clinical characteristics compared with other age groups and showed mixed Th2/Th17/Th22 skewing, indicating a unique pathogenesis for elderly AD.

A biofabricated vascularized skin model of atopic dermatitis for preclinical studies

Three-dimensional (3D) biofabrication techniques enable the production of multicellular tissue models as assay platforms for drug screening. The increased cellular and physiological complexity in these 3D tissue models should recapitulate the relevant biological environment found in the body. Here we describe the use of 3D bioprinting techniques to fabricate skin equivalent tissues of varying physiological complexity, including human epidermis, non-vascularized and vascularized full-thickness skin tissue equivalents, in a multi-well platform to enable drug screening. Human keratinocytes, fibroblasts, and pericytes, and induced pluripotent stem cell-derived endothelial cells were used in the biofabrication process to produce the varying complexity. The skin equivalents exhibit the correct structural markers of dermis and epidermis stratification, with physiological functions of the skin barrier. The robustness, versatility and reproducibility of the biofabrication techniques are further highlighted by the generation of atopic dermatitis (AD)-disease like tissues. These AD models demonstrate several clinical hallmarks of the disease, including: (i) spongiosis and hyperplasia; (ii) early and terminal expression of differentiation proteins; and (iii) increases in levels of pro-inflammatory cytokines. We show the pre-clinical relevance of the biofabricated AD tissue models to correct disease phenotype by testing the effects of dexamethasone, an anti-inflammatory corticosteroid, and three Janus Kinase inhibitors from clinical trials for AD. This study demonstrates the development of a versatile and reproducible bioprinting approach to create human skin equivalents with a range of cellular complexity for disease modeling. In addition, we establish several assay readouts that are quantifiable, robust, AD relevant, and can be scaled up for compound screening. The results show that the cellular complexity of the tissues develops a more physiologically relevant AD disease model. Thus, the skin models in this study offer an in vitro approach for the rapid understanding of pathological mechanisms, and testing for efficacy of action and toxic effects of drugs.

Therapeutic Effects of Chinese Herbal Formula (PTQX) on NC/Nga Mice with Atopic Dermatitis-Like Skin Lesions

Atopic dermatitis (AD), also known as atopic eczema, is a chronic pruritic inflammatory skin disease. The available systemic therapies for atopic dermatitis are inadequate. Objective. This study aimed to evaluate the effects of the Chinese herbal formula Pei Tu Qing Xin (PTQX) on dermatitis severity and ear swelling, immunomodulation, and the infiltration of mast cells in a mouse model of 1-chloro-2,4-dinitrobenzene- (DNCB-) induced AD. Methods. AD-like symptoms were induced by DNCB in NC/Nga mice. Skin lesions, dermatitis, ear swelling, and scratching behaviour were evaluated. Changes in the T-helper type 1 (Th1), Th2, Th17, and regulatory T (Treg) subtypes and immunoregulation in the spleen and lymph nodes were detected by flow cytometry. Results. Histopathological and immunohistochemical analyses demonstrated that PTQX decreased the DNCB-mediated induction of mast cells and infiltration of inflammatory cells in the ear and dorsal skin. PTQX also reduced the DNCB-induced increase in the serum immunoglobulin E level, pruritus, and dermatitis (red, flaky areas) on the dorsal skin. Furthermore, PTQX regulated the balance between the populations of Th1, Th2, Th17, and Treg cells (particularly the latter two) in the lymph nodes. Conclusions. Our results suggest that the Chinese herbal formula PTQX can alleviate symptoms of AD, such as epithelial damage, redness, swelling, and pruritus, and potentially be used to treat this condition.

MicroRNA‑146a as a potential regulator involved in the pathogenesis of atopic dermatitis

Previous studies have demonstrated that microRNA (miR)‑146a is involved in the inflammatory response of atopic dermatitis (AD). The aim of the present study was to investigate the expression of miR‑146a in the serum of patients with AD and in skin lesions of AD animal models. In addition, we aimed to predict and verify the target genes of miR‑146a. miR‑146a expression was measured in AD patient serum via reverse transcription‑quantitative PCR. T‑helper (Th)1 [CD4+; interferon (IFN)‑γ+] and Th2 [CD4+; interleukin (IL)‑4+] expression in peripheral blood mononuclear cells was evaluated using flow cytometry. Following the establishment of a 2,4‑dinitrofluorobenzene‑induced C57BL/6 mouse AD model, Th1 (CD4+IFN‑γ+) and Th2 (CD4+IL‑4+) expression was analyzed in murine spleen cells via flow cytometry. Plasmids were transfected into 293T cells and at 48 h post‑transfection, cells were analyzed using a luciferase assay system. The results revealed that the AD group had a significantly lower Th1/Th2 ratio and a significantly higher miR‑146a expression compared with the control group (P<0.05). Furthermore, a decreased Th1/Th2 ratio and a significantly increased miR‑146a expression were observed in the model group compared with the control group (P<0.01). We also conducted a dual‑luciferase assay to determine whether small ubiquitin‑related modifier 1 (SUMO1) if the target gene of miR‑146a. We observed a ~30% decrease in the relative luciferase activity in cells containing the 3'‑untranslated region of SUMO1 + miR‑146a). The results of the luciferase assay indicated that may be a direct mRNA target of miR‑146a; however, the quantification of band density of SUMO1 expression following western blotting did not significantly differ. The development of animal models in AD research is of vital importance. The results revealed that miR‑146a may be a potential regulator involved in the pathogenesis of AD. Furthermore, the current study determined that miR‑146a could be a valuable marker of AD and thus, may be applied in the development of therapeutic strategies for treating AD.

House dust mite-treated PAR2 over-expressor mouse: A novel model of atopic dermatitis

BACKGROUND

Atopic dermatitis (AD) is a complex skin disease involving causative effects from both intrinsic and extrinsic sources. Murine models of the disease often fall short in one of these components and, as a result, do not fully encapsulate these disease mechanisms.

OBJECTIVE

We aimed to determine whether the protease-activated receptor 2 over-expressor mouse (PAR2OE) with topical house dust mite (HDM) application is a more comprehensive and clinically representative AD model.

METHODS

Following HDM extract application to PAR2OE mice and controls, AD clinical scoring, itching behaviour, skin morphology and structure, barrier function, immune cell infiltration and inflammatory markers were assessed. Skin morphology was analysed using haematoxylin and eosin staining, and barrier function was assessed by transepidermal water loss measurements. Immune infiltrate was characterised by histological and immunofluorescence staining. Finally, an assessment of AD-related gene expression was performed using quantitative RT-PCR.

RESULTS

PAR2OE mice treated with HDM displays all the characteristic clinical symptoms including erythema, dryness and oedema, skin morphology, itch and inflammation typically seen in patients with AD. There is a significant influx of mast cells (P < .01) and eosinophils (P < .0001) into the dermis of these mice. Furthermore, the PAR2OE + HDM mice exhibit similar expression patterns of key differentially expressed genes as seen in human AD.

CONCLUSION

The PAR2OE + HDM mouse presents with a classic AD pathophysiology and is a valuable model in terms of reproducibility and overall disease representation to study the condition and potential therapeutic approaches.

Inhibitory effect of ethanol extract of Ampelopsis brevipedunculata rhizomes on atopic dermatitis-like skin inflammation

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts from various parts of Ampelopsis brevipedunculata has been used as anti-inflammatory agents in Asian folk medicine.

AIM OF THE STUDY

To demonstrate the medicinal effect of the A. brevipedunculata in skin inflammation, specifically atopic dermatitis (AD).

MATERIALS AND METHODS

The effect of ethanol extract of A. brevipedunculata rhizomes (ABE) on AD was examined using an AD-like skin inflammation model induced by repeated exposure to house dust mite (Dermatophagoides farinae extract, DFE) and 2,4-dinitrochlorobenzene (DNCB). The mechanism study was performed using tumor necrosis factor (TNF)-α and interferon (IFN)-γ-activated human keratinocytes (HaCaT). Serum histamine and immunoglobulin levels were quantified using enzymatic kits, while the gene expression of cytokines and chemokines was analyzed using quantitative real time polymerase chain reaction. The expression of signaling molecules was detected using Western blot.

RESULTS

Oral administration of ABE alleviated DFE/DNCB-induced ear thickening and clinical symptoms, as well as immune cell infiltration (mast cells and eosinophils) into the dermal layer. Serum Immunoglobulin (Ig) E, DFE-specific IgE, IgG2a, and histamine levels were decreased after the administration of ABE. ABE also inhibited CD4⁺IFN-γ⁺ and CD4⁺IL-4⁺ lymphocyte polarization in lymph nodes and expression of TNF-α, IFN-γ, IL-4, IL-13, and IL-31 in the ear tissue. In TNF-α/INF-γ-stimulated keratinocytes, ABE inhibited the gene expression of TNF-α, IL-6, IL-1β, and CCL17. In addition, ABE decreased the nuclear localization of signal transducer and activator of transcription 1 and nuclear factor-κB, and the phosphorylation of extracellular signal-regulated kinase and p38 mitogen-activated protein kinase.

CONCLUSION

Collectively, our data demonstrate the pharmacological role and signaling mechanism of ABE in the regulation of skin allergic inflammation, which supports our suggestion that ABE could be developed as a potential therapeutic agent for the treatment of AD.

Novel cutaneous mediators of chemical allergy

Chemical allergy can manifest into allergic contact dermatitis and asthma and the importance of skin sensitization in both of these diseases is increasingly being recognized. Given the unique characteristics of chemical allergy, coupled with the distinct immunological microenvironment of the skin research is still unraveling the mechanisms through which sensitization and elicitation occur. This review first describes the features of chemical sensitization and the known steps that must occur to develop a chemical allergy. Next, the unique immunological properties of the skin - which may influence chemical sensitization - are highlighted. Additionally, mediators involved with the development of allergy are reviewed, starting with early ones - including the properties of haptens, skin integrity, the microbiome, the inflammasome, and toll-like receptors (TLR). Novel cellular mediators of chemical sensitization are highlighted, including innate lymphoid cells, mast cells, T-helper (T_H) cell subsets, and skin intrinsic populations including γδ T-cells and resident memory T-cells. Finally, this review discusses two epigenetic mechanisms that can influence chemical sensitization, microRNAs and DNA methylation. Overall, this review highlights recent research investigating novel mediators of chemical allergy that are present in the skin. It also emphasizes the need to further explore these mediators to gain a better understanding of what makes a chemical an allergen, and how best to prevent the development of chemical-induced allergic diseases.

Quantitative profiling of cytokines and chemokines in DOCK8-deficient and atopic dermatitis patients

BACKGROUND

Hyper-IgE syndromes (HIES) are a clinically overlapping, heterogeneous group of inborn errors of immunity characterized by elevated serum IgE level, eosinophilia, atopy, and immune dysregulation. Deficiency of DOCK8 protein is potentially a life-threatening autosomal recessive HIES and only curable with bone marrow transplantation. Hence, the diagnosis of DOCK8 deficiency is critical and should be sought at an early stage to initiate definitive therapy.

METHODS

Serum samples from patients with DOCK8 deficiency and atopic dermatitis were profiled on a cytokine/chemokine panel for potential differential expression.

RESULTS

CXCL10 and TNF-A were upregulated in DOCK8 patients when compared to AD, possibly contributing toward increased susceptibility to infections and cancer. In contrast, epidermal growth factor (EGF) was significantly downregulated in a subgroup of DOCK8-deficient and AD patients, while IL-31 expression was comparable between both DOCK8-deficient and AD cohorts, possibly contributing toward pruritus seen in both groups.

CONCLUSION

This comprehensive cytokine profile in HIES patients reveals distinctive biomarkers that differentiate between the DOCK8-deficient and AD patients. The unique expression profile of various inflammatory cytokines in patients with DOCK8 deficiency vs atopic dermatitis likely reflects disease-specific perturbations in multiple cellular processes and pathways leading to a predisposition to infections and allergies seen in these patients. These data agree with the role for EGF replacement therapy in EGF-deficient individuals with AD as well as DOCK8 deficiency through a potential shared pathway. In addition, these novel biomarkers may be potentially useful in distinguishing DOCK8 deficiency from AD allowing early-targeted treatment options.

Association between endotoxin levels in dust from indoor swine housing environments and the immune responses of pigs

Indoor animal husbandry environments are inevitably contaminated with endotoxins. Endotoxin exposure is associated with various inflammatory illnesses in animals. This cross-sectional study evaluated the relationship between the degree of endotoxin exposure and the cellular and humoral immune profiles of fattening pigs. Blood samples were taken from the jugular vein of 47 pigs from ten pig farms in Korea. Whole blood cell counts and plasma immunoglobulin (Ig) classes were determined. Peripheral-blood mononuclear cells were stimulated in vitro with concanavalin A for 48 h, and cytokines released into culture supernatants were measured. The barns in which the pigs lived were assessed for endotoxin levels in the total and respirable dust by using the limulus amebocyte lysate kinetic QCL method. Low and high endotoxin exposures were defined as ≤ 30 and > 30 EU/m³, respectively. Compared to pigs with low endotoxin exposure (n = 19), highly exposed pigs (n = 28) had higher circulating neutrophil and lymphocyte (particularly B cells) counts, IgG and IgE levels, interferon-gamma (IFNγ) and interleukin (IL)-4 productions, and lower IgA levels and tumor necrosis factor-alpha (TNFα) production. The IL-4, IFNγ, and TNFα levels significantly correlated with endotoxin level and/or pig age. Constant exposure of pigs to high levels of airborne endotoxins can lead to aberrant immune profiles.

Protective effect of Paeoniae radix alba root extract on immune alterations in mice with atopic dermatitis

Atopic dermatitis is a progressive inflammatory disease characterized by type 2 helper T cell (T_H2) reactivity. The aim of this study was to examine the therapeutic effects of Paeoniae radix alba root extract using a murine model of atopic dermatitis. Atopic dermatitis was induced in a murine model characterized by immune alterations skewed toward T_H2 reactivity and pathophysiological dermal alterations which resemble human atopic dermatitis. The root extract at 1% or 6% was applied to the mouse dorsal skin for 3 weeks following induction of atopic dermatitis. Splenocytes were stimulated with immobilized anti-CD3 for 48 h to measure cytokine production. Levels of serum IgE, IgG1, and IgG2a were quantitated. Epidermal thickness and numbers of skin mast cells were determined. Mice in which atopic dermatitis was induced displayed increased numbers of skin mast cells, increased frequency of scratching, elevated serum IgE levels, increased ratios of IgG1 to IgG2a, and ratios of IL-4 to IFN-γ. The frequency of scratching was significantly decreased following application of 1% or 6% extract for 1 week. The root extract also reversed T_H2 skewing, as serum IgE levels, ratio of serum IgG1 to IgG2a, and ratio of IL-4 to IFN-γ production by in vitro-stimulated splenocytes were all suppressed following application of 1% or 6% extract for 3 weeks. Taken together Paeoniae radix alba root extract is suggested to reverse the immunological alterations and skin manifestations symptoms found in atopic dermatitis.

A preliminary study on topical ozonated oil in the therapeutic management of atopic dermatitis in murine

OBJECTIVE

To explore whether ozonated oil recovery atopic dermatitis (AD) via immunoregulation.

METHODS

Mice were repeatedly challenged with the triplex allergens of staphylococcal enterotoxin B, ovalbumin and calcipotriol ointment on the back to develop AD lesions, and were treated with ozonated oil. The lesional skins were scanned by reflectance confocal microscopy to measure the thickness of epidermis. The skin tissues were stained. Th1-type and Th2-type cytokines in serum and in tissues were detected by ELISA and real-time PCR, respectively.

RESULTS

Ozonated oil significantly inhibited inflammation and healed the lesions in 7 d. Ozonated oil inhibited NGF expression as compared to the groups treated with vehicle or PBS (p < .01).The serum proteins and lesional transcripts of Th2 cytokines including IL-4 and IL-31 were lower in the ozonated oil treated group than the groups treated with vehicle or PBS (p < .05). The IL-10 level was increased with treatment of ozonated oil (p < .01). On the other hand, the expressions of Th1 cytokines including IL-2, TNF-α, and IFN-γ in the serum were not regulated by ozonated oil.

CONCLUSIONS

Our results showed that ozonated oil could suppress inflammation in an AD murine via decreasing Th2-dominant cytokines response and increasing IL-10 expression. These suggest that ozonated oil may be a potential remedy for AD.

Profile of dupilumab and its potential in the treatment of inadequately controlled moderate-to-severe atopic dermatitis

Atopic dermatitis (AD) is a common inflammatory skin disorder that manifests as eczematous lesions, often associated with allergic rhinitis and asthma. Historically, moderate-to-severe disease has been managed with systemic immunosuppression, such as oral corticosteroids, which result in relapse and limiting side effects. Due to recent advancements in the identification of interleukin (IL)-4 and IL-13 as key mediators in AD, new biological agents have been developed for treatment. Dupilumab is a recently approved monoclonal antibody that targets the alpha subunit of the IL-4 receptor and, thus, downregulates activity of IL-4 and IL-13. This review discusses the profile of dupilumab and its potential for efficacy and safety in treating moderate-to-severe AD by reviewing data from Phase I–III clinical trials. Results suggest that dupilumab shows great therapeutic promise for AD. Further studies investigating extended use of dupilumab and dupilumab in comparison to other agents are needed to establish long-term efficacy and safety.

Molecular Mechanism of Atopic Dermatitis Induction Following Sensitization and Challenge with 2,4-Dinitrochlorobenzene in Mouse Skin Tissue

Laboratory animal models have been developed to investigate preventive or therapeutic effect of medicinal products, or occurrence or progression mechanism of atopic dermatitis (AD), a pruritic and persistent inflammatory skin disease. The murine model with immunologic phenomena resembling human AD was introduced, which demonstrated skewedness toward predominance of type-2 helper T cell reactivity and pathophysiological changes similar as human AD following 2,4-dinitrochlorobenzene (DNCB) sensitization and challenge. Molecular mechanism on the DNCB-mediated AD was further evaluated. Skin tissues were collected from mice treated with DNCB, and each tissue was equally divided into two sections; one for protein and the other for mRNA analysis. Expression of filaggrin, an important protein for keratinocyte integrity, was evaluated through SDS-PAGE. Level of mRNA expression for cytokines was determined through semi-quantitative reverse transcriptase polymerase chain reaction. Expression of filaggrin protein was significantly enhanced in the mice treated with DNCB compared with the vehicle (acetone : olive oil = 4 : 1 mixture) treatment group or the normal group without any treatment. Level of tumor necrosis factor-alpha and interleukin-18 mRNA expression, cytokines involved in activity of type-1 helper T (T_H1) cell, was significantly downregulated in the AD group compared with other control groups. These results suggest that suppression of T_H1 cell-mediated immune response could be reflected into the skin tissue of mice treated with DNCB for AD induction, and disturbance of keratinocyte integrity might evoke a compensatory mechanism.

Pseudolaric acid B attenuates atopic dermatitis-like skin lesions by inhibiting interleukin-17-induced inflammation

Pseudolaric acid B (PB), isolated from the extract of the root bark of Pseudolarix kaempferi Gordon, has been used as a traditional remedy for the treatment of skin diseases. However, the information of PB on atopic dermatitis (AD) remains largely unknown. In the present study, oral administration with PB improved the severity scores of AD-like skin lesions dose-dependently in NC/Nga mice through reducing serum IgE, pro-inflammatory cytokines, and the infiltration of inflammatory cells. In addition, PB significantly attenuated the levels of IL-17 and IL-22, and the proportion of Th17 cells in NC/Nga mice, as well as decreased IL-17-induced inflammation in RAW264.7 cells. Moreover, PB inhibited the phosphorylation of IκBα and miR-155 expression both in NC/Nga mice and in IL-17-stimulated RAW264.7 cells, which could be reversed by GW9662, a specific antagonist for PPARγ. The incorporation of GW9662 reversed the inhibitory effect of PB on the RORγ-mediated activation of the Il17 promoter. Transfection with PPARγ luciferase reporter gene further demonstrated the enhancement of PB on PPARγ transactivation. These findings indicate that PB could ameliorate AD-like skin lesions by inhibiting IL-17-induced inflammation in a PPARγ-dependent manner, which would provide experimental evidence of PB for the therapeutic potential on AD and other inflammatory skin diseases.

An Update on the Pathophysiology of Atopic Dermatitis

Atopic dermatitis (AD) is increasingly recognized as a complex, inflammatory skin disease involving interplay of multiple elements. This article notes key advances in understanding of immune dysregulation, skin barrier dysfunction, environmental, genetic, and microbial influences orchestrating disease pathogenesis, and the relevance of therapeutic interventions in each area. Accumulating evidence and the discovery of new T-cell subsets has matured AD as a multiple-cytokine-axes-driven disorder, evolved from the widely held belief of it being a biphasic Th1/Th2 disease. These new insights have led to active trials testing multiple, targeted therapeutics with better efficacy and safety-profiles.

Sensitivity to oxazolone induced dermatitis is transferable with gut microbiota in mice

Atopic Dermatitis (AD) has been associated with gut microbiota (GM) dysbiosis in humans, indicating a causative role of GM in AD etiology. Furthermore, the GM strongly correlates to essential disease parameters in the well-known oxazolone-induced mouse model of AD. Here, we demonstrate that it is possible to transfer both a high-responding and a low-responding AD phenotype with GM from conventional mice to germ-free mice. The mice inoculated with the high-responding GM had significantly higher clinical score, increased ear thickness, and increased levels of IL-1β, TNFα, IL-4, IL-5, and IL-6 compared to the mice inoculated with the low-responding GM. The inter-individual variation was in general not affected by this increase in effect size. Germ-free mice induced with AD revealed a high disease response as well as high inter-individual variation indicating protective properties of certain microbial taxa in this model. This study underlines that the GM has a strong impact on AD in mouse models, and that the power of studies may be increased by the application of mice inoculated with a specific GM from high responders to increase the effect size.

Th9 cytokines response and its possible implications in the immunopathogenesis of leprosy

AIMS

Leprosy is an infectious-contagious disease whose clinical evolution depends on the interaction of the infectious agent with the immune response of the host, leading to a clinical spectrum that ranges from lepromatous leprosy (susceptibility, LL) to tuberculoid leprosy (resistance, TT). The immune response profile will depend on the pattern of cytokine production and on the activity of macrophages during infection. Classically, the clinical evolution of leprosy has been associated with Th1/Th2 cytokine profiles, but the role of new cytokine profiles such as T helper 9 (Th9) remains to be elucidated.

METHODS

To evaluate the tissue expression profile of these cytokines, a cross-sectional study was conducted using a sample of 30 leprosy skin lesion biopsies obtained from patients with leprosy, 16 TT and 14 lepromatous LL.

RESULTS

Immunohistochemical analysis revealed a significant difference in interleukin (IL)-9, IL-4 transforming growth factor (TGF)-β and IL-10 levels between the two groups. IL-9 was more expressed in TT lesions compared with LL lesions. Higher expression of IL-4, IL-10 and TGF-β was observed in LL compared with TT. IL-4, IL-10 and TGF-β tended to be negatively correlated with the expression of IL-9, indicating a possible antagonistic activity in tissue.

CONCLUSIONS

The results suggest that Th9 lymphocytes may be involved in the response to Mycobacterium leprae, positively or negatively regulating microbicidal activity of the local immune system in the disease.

Early Activation of Th2/Th22 Inflammatory and Pruritogenic Pathways in Acute Canine Atopic Dermatitis Skin Lesions

Determining inflammation and itch pathway activation in patients with atopic dermatitis (AD) is fraught with the inability to precisely assess the age of skin lesions, thus affecting the analysis of time-dependent mediators. To characterize inflammatory events occurring during early experimental acute AD lesions, biopsy samples were collected 6, 24, and 48 hours after epicutaneous application of Dermatophagoides farinae house dust mites to sensitized atopic dogs. The skin transcriptome was assessed using a dog-specific microarray and quantitative PCR. Acute canine AD skin lesions had a significant up-regulation of genes encoding T helper (Th) 2 (e.g., IL4, IL5, IL13, IL31, and IL33), Th9 (IL9), and Th22 (IL22) cytokines as well as Th2-promoting chemokines such as CCL5 and CCL17. Proinflammatory (e.g., IL6, LTB, and IL18) cytokines were also up-regulated. Other known pruritogenic pathways were also activated: there was significant up-regulation of genes encoding proteases cathepsin S (CTSS), mast cell chymase (CMA1), tryptase (TPS1) and mastin, neuromedin-B (NMB), nerve growth factor (NGF), and leukotriene-synthesis enzymes (ALOX5, ALOX5AP, and LTA4H). Experimental acute canine house dust mite-induced AD lesions exhibit an activation of innate and adaptive immune responses and pruritogenic pathways similar to those seen in humans with acute AD, thereby validating this model to test innovative therapeutics modalities for this disease.