Regulation of Filaggrin, Loricrin, and Involucrin by IL-4, IL-13, IL-17A, IL-22, AHR, and NRF2: Pathogenic Implications in Atopic Dermatitis

Th2 Cytokines Affect the Innate Immune Barrier without Impairing the Physical Barrier in a 3D Model of Normal Human Skin

(1) Background: Atopic dermatitis is one of the most common inflammatory skin diseases characterized by T helper (Th) 2 and Th22 cells producing interleukin (IL)-4/IL-13 and IL-22, respectively. The specific contribution of each cytokine to the impairment of the physical and the immune barrier via Toll-like receptors (TLRs) is poorly addressed concerning the epidermal compartment of the skin. (2) Methods: The effect of IL-4, IL-13, IL-22, and the master cytokine IL-23 is evaluated in a 3D model of normal human skin biopsies (n = 7) at the air-liquid interface for 24 and 48 h. We investigated by immunofluorescence the expressions of (i) claudin-1, zonula occludens (ZO)-1 filaggrin, involucrin for the physical barrier and (ii) TLR2, 4, 7, 9, human beta-defensin 2 (hBD-2) for the immune barrier. (3) Results: Th2 cytokines induce spongiosis and fail in impairing tight junction composition, while IL-22 reduces and IL-23 induces claudin-1 expression. IL-4 and IL-13 affect the TLR-mediated barrier largely than IL-22 and IL-23. IL-4 early inhibits hBD-2 expression, while IL-22 and IL-23 induce its distribution. (4) Conclusions: This experimental approach looks to the pathogenesis of AD through molecular epidermal proteins rather than cytokines only and paves the way for tailored patient therapy.

Scleral Proteome in Noninfectious Scleritis Unravels Upregulation of Filaggrin-2 and Signs of Neovascularization

Purpose

Scleritis is a severe inflammatory ocular disorder with unknown pathogenesis. We investigated healthy sclera as well as sclera affected by noninfectious scleritis for differentially expressed proteins using a mass spectrometry approach.

Methods

We collected scleral samples of enucleated eyes due to severe noninfectious scleritis (n = 3), and control scleral tissues (n = 5), all exenterated eyes for eyelid carcinomas (n = 4), or choroidal melanoma (n = 1) without scleral invasion. Samples were prepared for the nano liquid-chromatography mass spectrometer (LC-MS), data were analyzed using proteomics software (Scaffold), and is available via ProteomeXchange (identifier PXD038727). Samples were also stained for immuno-histopathological evaluation.

Results

Mass spectrometry identified 629 proteins within the healthy and diseased scleral tissues, whereof collagen type XII, VI, and I were the most abundantly expressed protein. Collagen type II-XII was also present. Filaggrin-2, a protein that plays a crucial role in epidermal barrier function, was found upregulated in all scleritis cases. In addition, other epithelial associated proteins were upregulated (such as keratin 33b, 34, and 85, epiplakin, transglutaminase-3, galectin 7, and caspase-14) in scleritis. Further, upregulated proteins involved in regulation of the cytoskeleton (vinculin and myosin 9), and housekeeping proteins were found (elongation factor-2 and cytoplasmic dynein 1) in our study. Upregulation of filaggrin-2 and myosin-9 was confirmed with immunohistochemistry, the latter protein showing co-localization with the endothelial cell marker ETC-related gene (ERG), indicating neovascularization in scleral tissue affected by scleritis.

Conclusions

We found upregulation of filaggrin-2 and signs of neovascularization in scleral tissue of patients with noninfectious scleritis. Further research, ideally including more scleritis cases, is needed to validate our findings.

Association of TLR2 and TLR9 gene polymorphisms with atopic dermatitis: a systematic review and meta-analysis with trial sequential analysis

Atopic dermatitis (AD) is a chronic, inflammatory skin disease. The mechanism was complex. Genetic mutations of Toll-like receptor (TLR) may be associated with AD, yet still unclear. We aim to provide specific evidence of the association of TLR2, TLR9 gene polymorphisms with AD. Publications were selected according to the criteria. Newcastle-Ottawa Scale was applied to evaluate the quality. The value of ORs and 95%CIs were applied to measure the associations. According to the heterogeneity, the effects model of fixed or random was selected in data combination. For TLR2 gene rs5743708 polymorphism, under allele and recessive contrasts, the pooled data showed a significant correlation, which was A vs a, OR = 0.51 (95%CI: 0.30, 0.86); AA vs Aa + aa, OR = 0.54 (95%CI: 0.33, 0.88). For TLR2 gene rs4696480 polymorphism, under allele, homozygous, heterozygous, and dominant contrasts, the pooled data showed a significant correlation, which was A vs a, OR = 0.79 (95%CI: 0.64, 0.97), AA vs aa, OR = 0.65 (95%CI: 0.43, 0.97), Aa vs aa, OR = 0.68 (95%CI: 0.48, 0.97), AA + Aa vs aa, OR = 0.67 (95%CI: 0.49, 0.93). There are significant associations of TLR2 gene rs5743708, rs4696480 polymorphisms with atopic dermatitis, while no associations are found in TLR9 gene rs5743836, rs187084 polymorphisms.

Epicutaneous Sensitization and Food Allergy: Preventive Strategies Targeting Skin Barrier Repair-Facts and Challenges

Food allergy represents a growing public health and socio-economic problem with an increasing prevalence over the last two decades. Despite its substantial impact on the quality of life, current treatment options for food allergy are limited to strict allergen avoidance and emergency management, creating an urgent need for effective preventive strategies. Advances in the understanding of the food allergy pathogenesis allow to develop more precise approaches targeting specific pathophysiological pathways. Recently, the skin has become an important target for food allergy prevention strategies, as it has been hypothesized that allergen exposure through the impaired skin barrier might induce an immune response resulting in subsequent development of food allergy. This review aims to discuss current evidence supporting this complex interplay between the skin barrier dysfunction and food allergy by highlighting the crucial role of epicutaneous sensitization in the causality pathway leading to food allergen sensitization and progression to clinical food allergy. We also summarize recently studied prophylactic and therapeutic interventions targeting the skin barrier repair as an emerging food allergy prevention strategy and discuss current evidence controversies and future challenges. Further studies are needed before these promising strategies can be routinely implemented as prevention advice for the general population.

CYSRT1: an antimicrobial epidermal protein that can interact with late cornified envelope (LCE) proteins

Late cornified envelope (LCE) proteins are small cationic epidermal proteins with antimicrobial properties, and the combined deletion of LCE3B and LCE3C genes is a risk factor for psoriasis that affects skin microbiome composition. In a yeast two-hybrid screen we identified cysteine-rich tail 1 protein (CYSRT1) as an interacting partner of members of all LCE groups except LCE6. These interactions were confirmed in a mammalian cell system by co-immunoprecipitation. CYSRT1 is a protein of unknown function that is specifically expressed in cutaneous and oral epithelia and spatially colocalizes with LCE proteins in the upper layers of the suprabasal epidermis. Constitutive CYSRT1 expression is present in fully differentiated epidermis and can be further induced in vivo by disruption of the skin barrier upon stratum corneum removal. Transcriptional regulation correlates to keratinocyte terminal differentiation but not to skin bacteria exposure. Similar to LCEs, CYSRT1 was found to have antibacterial activity against Pseudomonas aeruginosa. Comparative gene sequence analysis and protein amino acid alignment indicates that CYSRT1 is highly conserved among vertebrates and has putative antimicrobial activity. To summarize, we identified CYSRT1 in the outer skin layer, where it colocalizes with LCE proteins and contributes to the constitutive epidermal antimicrobial host defense repertoire.

Quantitative Proteomics Identifies Reduced NRF2 Activity and Mitochondrial Dysfunction in Atopic Dermatitis

Atopic dermatitis is the most common inflammatory skin disease and is characterized by a deficient epidermal barrier and cutaneous inflammation. Genetic studies suggest a key role of keratinocytes in atopic dermatitis pathogenesis, but the alterations in the proteome that occur in the full epidermis have not been defined. Using a pressure-cycling technology and data-independent acquisition approach, we performed quantitative proteomics of epidermis from healthy volunteers and lesional and nonlesional patient skin. Results were validated by targeted proteomics using parallel reaction monitoring mass spectrometry and immunofluorescence staining. Proteins that were differentially abundant in the epidermis of patients with atopic dermatitis versus in healthy control reflect the strong inflammation in lesional skin and the defect in keratinocyte differentiation and epidermal stratification that already characterizes nonlesional skin. Most importantly, they reveal impaired activation of the NRF2-antioxidant pathway and reduced abundance of mitochondrial proteins involved in key metabolic pathways in the affected epidermis. Analysis of primary human keratinocytes with small interfering RNA‒mediated NRF2 knockdown revealed that the impaired NRF2 activation and mitochondrial abnormalities are partially interlinked. These results provide insight into the molecular alterations in the epidermis of patients with atopic dermatitis and identify potential targets for pharmaceutical intervention.

The evolving landscape of biologic therapies for atopic dermatitis: Present and future perspective

Atopic dermatitis (AD) is one of the most common, chronic inflammatory skin diseases with a significant physical, emotional and socioeconomic burden. In recent years the understanding of AD pathogenesis has expanded from the Th2-centred perspective, with the recognition of the involvement of other immune axes. In different AD endotypes, influenced by environment, genetics and race, transcriptomic profiles have identified differing contributions of multiple immune axes such as, Th17, Th22 and Th1. The enriched pathogenic model of AD has catalysed the development of numerous biologic therapies targeting a range of key molecules implicated in disease progression. Currently, dupilumab and tralokinumab, which both target the Th2 pathway, are the only approved biologic therapies for AD in the United States and Europe. New biologic therapies in development, however, target different Th2-pathway molecules along with cytokines in other immune axes, including Th17 and Th22, offering promise for varied treatments for this heterogeneous disease. As the biologic pipeline advances, the integration into clinical practice and approval of these experimental biologics may provide more effective, tailored therapeutic solutions and illuminate on the pathologic processes of AD across a broader, more diverse patient population.

Atopic Dermatitis and Water: Is There an Optimum Water Intake Level for Improving Atopic Skin?

Water is a vital nutrient with innumerable functions for every living cell. The functions of human skin include protection against dehydration of the body. Atopic dermatitis (AD) is a chronic pruritic inflammatory skin disease that presents with dry skin, erythematous and eczematous lesions, and lichenification. This paper discusses the question of whether extra water intake in children with AD affects skin hydration and the skin barrier function. Among the methods used to treat dry skin, topical leave-on products are the first-line treatment, intended to improve hydration and the skin barrier function. The effectiveness of adequate water intake as a measure to treat dry skin is still under debate. Normal skin hydration increases with dietary water intake, particularly in those with prior lower water consumption. Skin dryness in AD is instrumental to the itch and inflammation cycle, contributing to barrier impairment and aggravating disease severity and flares. Certain emollients provide significant hydration to AD skin, with relief of dryness and reduction in barrier impairment, disease severity, and flares. Further investigations are needed to evaluate the optimum water intake levels in children with AD, as important questions remain unanswered, namely, does oral hydration provide relief of skin dryness and reduce barrier impairment, disease severity, and flares; is there any additional benefit from using mineral or thermal spring water; or is there a need to specifically study the fluid/water intake in children with AD and food allergy (FA) restrictions?

Tapinarof for psoriasis and atopic dermatitis: 15 years of clinical research

Tapinarof is a topical, aryl-hydrocarbon receptor agonist that has recently received FDA-approval for the treatment of psoriasis. This novel therapeutic has also been shown to be effective for atopic dermatitis and is currently in phase 3 for this indication. Beyond good efficacy and fast onset of action in patients with psoriasis, the clinical response to tapinarof is notable for durable remission or near remission, maintained for an average of 130 days beyond treatment discontinuation in patients with psoriasis in phase 3 studies. Tapinarof is usually well tolerated but can induce a follicular inflammatory reaction and dermatitis in some patients. This narrative review covers the historical development of this molecule, safety and efficacy data from clinical trials conducted with various topical formulations, and practical considerations derived from our 15 years of clinical trial experience with the drug.

Optimization of long-range PCR protocol to prepare filaggrin exon 3 libraries for PacBio long-read sequencing

BACKGROUND

The filaggrin (FLG) protein, encoded by the FLG gene, is an intermediate filament-associated protein that plays a crucial role in the terminal stages of human epidermal differentiation. Loss-of-function mutations in the FLG exon 3 have been associated with skin diseases. The identification of causative mutations is challenging, due to the high sequence homology within its exon 3 (12,753 bp), which includes 10 to 12 filaggrin tandem repeats. With this study we aimed to obtain the whole FLG exon 3 sequence through PacBio technology, once 13-kb amplicons have been generated.

METHODS AND RESULTS

For the preparation of SMRTbell libraries to be sequenced using PacBio technology, we focused on optimizing a 2-step long-range PCR protocol to generate 13-kb amplicons covering the whole FLG exon 3 sequence. The performance of three long-range DNA polymerases was assessed in an attempt to improve the PCR conditions required for the enzymes to function properly. We focused on optimization of the input template DNA concentration and thermocycling parameters to correctly amplify the entire FLG exon 3 sequence, minimizing non-specific amplification.

CONCLUSIONS

Taken together, our findings suggested that the PrimeSTAR protocol is suitable for producing the amplicons of the 13-kb FLG whole exon 3 to prepare SMRTbell libraries. We suggest that sequencing the generated amplicons may be useful for identifying LoF variants that are causative of the patients' disorders.

Keratinocytes coordinate inflammatory responses and regulate development of secondary lymphedema

Epidermal changes are histological hallmarks of secondary lymphedema, but it is unknown if keratinocytes contribute to its pathophysiology. Using clinical lymphedema specimens and mouse models, we show that keratinocytes play a primary role in lymphedema development by producing T-helper 2 (Th2) -inducing cytokines. Specifically, we find that keratinocyte proliferation and expression of protease-activated receptor 2 (PAR2) are early responses following lymphatic injury and regulate the expression of Th2-inducing cytokines, migration of Langerhans cells, and skin infiltration of Th2-differentiated T cells. Furthermore, inhibition of PAR2 activation with a small molecule inhibitor or the proliferation inhibitor teriflunomide (TF) prevents activation of keratinocytes stimulated with lymphedema fluid. Finally, topical TF is highly effective for decreasing swelling, fibrosis, and inflammation in a preclinical mouse model. Our findings suggest that lymphedema is a chronic inflammatory skin disease, and topically targeting keratinocyte activation may be a clinically effective therapy for this condition.

Staphylococcus Infection: Relapsing Atopic Dermatitis and Microbial Restoration

Atopic Dermatitis (AD) skin is susceptible to Staphylococcus aureus (SA) infection, potentially exposing it to a plethora of toxins and virulent determinants, including Panton-Valentine leukocidin (PVL) (α-hemolysin (Hla) and phenol-soluble modulins (PSMs)), and superantigens. Depending on the degree of infection (superficial or invasive), clinical treatments may encompass permanganate (aq) and bleach solutions coupled with intravenous/oral antibiotics such as amoxicillin, vancomycin, doxycycline, clindamycin, daptomycin, telavancin, linezolid, or tigecycline. However, when the skin is significantly traumatized (sheathing of epidermal sections), an SA infection can rapidly ensue, impairing the immune system, and inducing local and systemic AD presentations in susceptible areas. Furthermore, when AD presents systemically, desensitization can be long (years) and intertwined with periods of relapse. In such circumstances, the identification of triggers (stress or infection) and severity of the flare need careful monitoring (preferably in real-time) so that tailored treatments targeting the underlying pathological mechanisms (SA toxins, elevated immunoglobulins, impaired healing) can be modified, permitting rapid resolution of symptoms.

Protective effect of Saussurea involucrata polysaccharide against skin dryness induced by ultraviolet radiation

Background: Exposure to ultraviolet B (UVB) radiation can damage the epidermis barrier function and eventually result in skin dryness. At present, little work is being devoted to skin dryness. Searching for active ingredients that can protect the skin against UVB-induced dryness will have scientific significance. Methods: Saussurea involucrata polysaccharide (SIP) has been shown to have significant antioxidant and anti-photodamage effects on the skin following UVB irradiation. To evaluate the effect of SIP on UVB-induced skin dryness ex vivo, SIP-containing hydrogel was applied in a mouse model following exposure to UVB and the levels of histopathological changes, DNA damage, inflammation, keratinocyte differentiation, lipid content were then evaluated. The underlying mechanisms of SIP to protect the cells against UVB induced-dryness were determined in HaCaT cells. Results: SIP was found to lower UVB-induced oxidative stress and DNA damage while increasing keratinocyte differentiation and lipid production. Western blot analysis of UVB-irradiated skin tissue revealed a significant increase in peroxisome proliferator-activated receptor-α (PPAR-α) levels, indicating that the underlying mechanism may be related to PPAR-α signaling pathway activation. Conclusions: By activating the PPAR-α pathway, SIP could alleviate UVB-induced oxidative stress and inhibit the inflammatory response, regulate proliferation and differentiation of keratinocytes, and mitigate lipid synthesis disorder. These findings could provide candidate active ingredients with relatively clear mechanistic actions for the development of skin sunscreen moisturizers.

Effects of Dupilumab on Itch-Related Events in Atopic Dermatitis: Implications for Assessing Treatment Efficacy in Clinical Practice

Dupilumab attenuates itch and skin inflammation in patients with atopic dermatitis (AD). However, itch-related events that are improved by dupilumab remain unclear. Therefore, the present study investigated changes in clinical scores, serum biomarkers, and the number of intraepidermal nerve fibers (IENFs) using skin biopsies and blood samples from 12 patients with moderate to severe AD before and after treatment with dupilumab. Clinical manifestations were assessed using eczema area and severity index (EASI) and visual analogue scale (VAS) scores at baseline and after 8 and 16 weeks of treatment. Serum levels of total immunoglobulin E (IgE), thymus and activation-regulated chemokine (TARC), interleukin (IL)-4, IL-13, IL-22, and IL-31 were examined by electrochemiluminescence, chemiluminescent enzyme immunoassays, ProQuantum immunoassays, and enzyme-linked immunosorbent assays (ELISA) at baseline and after 8 and 16 weeks of treatment. In skin biopsies from AD patients at baseline and after 16 weeks of treatment, IENFs were examined immunohistochemically with the anti-protein gene product (PGP) 9.5 antibody. The dupilumab treatment significantly improved EASI and VAS scores and decreased serum levels of TARC, IgE, and IL-22, whereas those of IL-13 and IL-31, and the number of IENFs remained unchanged and those of IL-4 increased. VAS scores were positively correlated with serum TARC, IL-22, and IgE levels and the degree of epidermal thickening. Serum IL-31 levels were positively correlated with the number of IENFs. These results suggest that serum TARC, IL-22, and IgE levels and epidermal thickness are itch-related events associated with dupilumab treatment and that serum IL-31 levels may reflect the degree of IENF density in AD patients. Therefore, dynamic changes may be used to assess the efficacy of dupilumab treatment to treat itching and inflammation in patients with AD.

Immunopathogenesis of Atopic Dermatitis: Focus on Interleukins as Disease Drivers and Therapeutic Targets for Novel Treatments

Atopic dermatitis is a chronic, recurrent inflammatory skin disorder manifesting by eczematous lesions and intense pruritus. Atopic dermatitis develops primarily as a result of an epidermal barrier defect and immunological imbalance. Advances in understanding these pathogenetic hallmarks, and particularly the complex role of interleukins as atopic dermatitis drivers, resulted in achieving significant therapeutic breakthroughs. Novel medications involve monoclonal antibodies specifically blocking the function of selected interleukins and small molecules such as Janus kinase inhibitors limiting downstream signaling to reduce the expression of a wider array of proinflammatory factors. Nevertheless, a subset of patients remains refractory to those treatments, highlighting the complexity of atopic dermatitis immunopathogenesis in different populations. In this review, we address the immunological heterogeneity of atopic dermatitis endotypes and phenotypes and present novel interleukin-oriented therapies for this disease.

Wound healing activity of aqueous dispersion of fullerene C60 produced by "green technology"

In addition to exhibited antioxidant and anti-inflammatory activity, fullerene C60 is a promising wound healing agent. An important stage in the production of fullerene-based ointments is the stability of the aqueous fullerene dispersion (AFD) with minimum size of colloidal fullerene aggregates and sufficiently high concentration. To achieve these parameters tangential flow filtration of fullerene C60 was used ("green technology"). As estimated by small-angle neutron scattering and dynamic light scattering purified AFDs with narrow-size distribution nanoclusters have a size of 6 nm and are assembled into agglomerates which reach a size of 150 nm. The ability of the AFD to exhibit regenerative activity was studied using the animal wound model. This study shows for the first time that the fullerene-based composition stimulates the healing of wounds of various origins. We assume that the mechanism of the AFD wound-healing activity is associated with the aryl hydrocarbon receptor and macrophages activity.

Morus alba fruits attenuates atopic dermatitis symptoms and pathology in vivo and in vitro via the regulation of barrier function, immune response and pruritus

BACKGROUND

Morus alba fruits (MAF) belong to the Moraceae family, which are known to be effective in treating diabetic, autoimmune, and hormonal diseases owing to its low toxicity. MAF, as excerpted from Donguibogam, a representative Korean medical encyclopedia protected by UNESCO, has been widely used to treat lumbago, arthritis, and diabetes. Based on these effects, MAF is investigated for unidentified effects of atopic dermatitis, characterized by complex etiology of skin barrier dysfunction, inflammation, and chronic pruritus.

METHODS

The antioxidant, inflammatory, and immunomodulatory properties of MAF and its bioactive compounds have been widely reported. According to an examination of 1-chloro-2,4-dinitrobenzene-induced AD-like skin lesions in NC/Nga mice, AD symptoms, such as increased dermatitis score, scratching frequency, immunoglobulin E, trans-epidermal water loss, epidermal thickness, and infiltration of mast cells, were relieved by topical MAF administration. They effectively attenuated cytokines and chemokines, such as interleukin (IL)-4, IL-5, IL-6, IL-8, IL-13, IL-17A, IL-22, IL-1β, tumor necrosis factor-α, thymic stromal lymphopoietin (TSLP), thymic- and activation-regulated chemokine, normal T cell expression, and macrophage-derived chemokine secretion at the mRNA level in TNF-α/IFN-γ induced HaCaT (human immortalized keratinocyte) cells.

RESULTS

Both in vivo and in vitro models, MAF increased the expression of filaggrin, involucrin, and loricrin, as well as inhibited the activation of Janus kinase 2, signal transducer and activator of transcription proteins 1, and mitogen-activated protein kinase pathways, including extracellular signal-regulated kinase, c-jun N-terminal kinase, and p38. Moreover, MAF reduced the expression of TSLP and periostin, which play important roles in skin pruritus as chronic pruritogenic factors.

CONCLUSION

These data indicate that MAF could be used as a potential treatment for AD-like skin lesions by regulating the inflammatory response, improving physical skin barriers, and relieving symptomatic pruritus.

Immunization with a Pneumococcal pep27 Mutant Strain Alleviates Atopic Dermatitis through the Upregulation of Regulatory T-Cell Activity and Epithelial Barrier Function and Suppressing TSLP Expression

Atopic dermatitis (AD) is an inflammatory disease driven in part by type 2 helper T (Th2) cytokines and skin barrier disruption alleviating the entry of allergens. Thymic stromal lymphopoietin (TSLP), an epithelial cell‒derived cytokine, is known to aggravate AD symptoms by activating Th2. In addition, regulatory T cells (Tregs) inhibit inflammatory cells such as Th2. However, the relationship between TSLP and Tregs in AD is unclear. A murine dermatitis model was induced by applying oxazolone to the ear skin of mice. Prophylactic and therapeutic responses were analyzed by immunizing mice intranasally with a pneumococcal pep27 mutant (Δpep27 mutant), attenuated strain by reducing the virulence of a pathogen. Intranasal immunization with a pneumococcal pep27 mutant could elicit anti-inflammatory Treg-relevant factors and epithelial barrier genes (loricrin, involucrin, filaggrin, and small proline-rich repeat proteins). Thus, pneumococcal pep27-mutant immunization suppressed epidermal collapse, IgE, TSLP, and upregulation of Th2 expression by upregulating Treg activity. In contrast, Treg inhibition aggravated AD symptoms through the upregulation of TSLP and Th2 and the repression of epithelial barrier function compared with that of the noninhibited pneumococcal Δpep27-mutant group. Taken together, immunization with pneumococcal Δpep27 mutant upregulated Treg and epithelial barrier function and inhibited TSLP and Th2 to relieve AD symptoms.

Advances in Current Drugs and Formulations for the Management of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic, relapsing inflammatory skin disease with a complex pathophysiology. Treatment of AD remains challenging owing to the presence of a wide spectrum of clinical phenotypes and limited response to existing therapies. However, recent genetic, immunological, and pathophysiological insights into the disease mechanism resulted in the invention of novel therapeutic drug candidates. This review provides a comprehensive overview of current therapies and assesses various novel drug delivery strategies currently under clinical investigation. Further, this review majorly emphasizes on various topical treatments including emollient therapies, barrier repair agents, topical corticosteroids (TCS), phosphodiesterase 4 (PDE4) inhibitors, calcineurin inhibitors, and Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway inhibitors. It also discusses biological and systemic therapies, upcoming treatments based on ongoing clinical trials. Additionally, this review scrutinized the use of pharmaceutical inactive ingredients in the approved topical dosage forms for AD treatment.

NRF2 in dermo-cosmetic: From scientific knowledge to skin care products

The skin is the organ that is most susceptible to the impact of the exposome. Located at the interface with the external environment, it protects internal organs through the barrier function of the epidermis. It must adapt to the consequences of the harmful effects of solar radiation, the various chemical constituents of atmospheric pollution, and wounds associated with mechanical damage: oxidation, cytotoxicity, inflammation, and so forth. In this biological context, a capacity to adapt to the various stresses caused by the exposome is essential; otherwise, more or less serious conditions may develop accelerated aging, pigmentation disorders, atopy, psoriasis, and skin cancers. Nrf2-controlled pathways play a key role at this level. Nrf2 is a transcription factor that controls genes involved in oxidative stress protection and detoxification of chemicals. Its involvement in UV protection, reduction of inflammation in processes associated with healing, epidermal differentiation for barrier function, and hair regrowth, has been demonstrated. The modulation of Nrf2 in the skin may therefore constitute a skin protection or care strategy for certain dermatological stresses and disorders initiated or aggravated by the exposome. Nrf2 inducers can act through different modes of action. Keap1-dependent mechanisms include modification of the cysteine residues of Keap1 by (pro)electrophiles or prooxidants, and disruption of the Keap1-Nrf2 complex. Indirect mechanisms are suggested for numerous phytochemicals, acting on upstream pathways, or via hormesis. While developing novel and safe Nrf2 modulators for skin care may be challenging, new avenues can arise from natural compounds-based molecular modeling and emerging concepts such as epigenetic regulation.

Oxidative Stress and Phototherapy in Atopic Dermatitis: Mechanisms, Role, and Future Perspectives

Atopic dermatitis is a chronic inflammatory skin disease in which the overproduction of reactive oxygen species plays a pivotal role in the pathogenesis and persistence of inflammatory lesions. Phototherapy represents one of the most used therapeutic options, with benefits in the clinical picture. Studies have demonstrated the immunomodulatory effect of phototherapy and its role in reducing molecule hallmarks of oxidative stress. In this review, we report the data present in literature dealing with the main signaling molecular pathways involved in oxidative stress after phototherapy to target atopic dermatitis-affected cells. Since oxidative stress plays a pivotal role in the pathogenesis of atopic dermatitis and its flare-up, new research lines could be opened to study new drugs that act on this mechanism, perhaps in concert with phototherapy.

Thermostable Proteins from HaCaT Keratinocytes Identify a Wide Breadth of Intrinsically Disordered Proteins and Candidates for Liquid-Liquid Phase Separation

Intrinsically disordered proteins (IDPs) move through an ensemble of conformations which allows multitudinous roles within a cell. Keratinocytes, the predominant cell type in mammalian epidermis, have had only a few individual proteins assessed for intrinsic disorder and its possible contribution to liquid-liquid phase separation (LLPS), especially in regard to what functions or structures these proteins provide. We took a holistic approach to keratinocyte IDPs starting with enrichment via the isolation of thermostable proteins. The keratinocyte protein involucrin, known for its resistance to heat denaturation, served as a marker. It and other thermostable proteins were identified by liquid chromatography tandem mass spectrometry and subjected to extensive bioinformatic analysis covering gene ontology, intrinsic disorder, and potential for LLPS. Numerous proteins unique to keratinocytes and other proteins with shared expression in multiple cell types were identified to have IDP traits (e.g., compositional bias, nucleic acid binding, and repeat motifs). Among keratinocyte-specific proteins, many that co-assemble with involucrin into the cell-specific structure known as the cornified envelope scored highly for intrinsic disorder and potential for LLPS. This suggests intrinsic disorder and LLPS are previously unrecognized traits for assembly of the cornified envelope, echoing the contribution of intrinsic disorder and LLPS to more widely encountered features such as stress granules and PML bodies.

Galactomyces Ferment Filtrate Potentiates an Anti-Inflammaging System in Keratinocytes

Skincare products play a crucial role in preventing the dry skin induced by various causes. Certain ingredients can help to improve the efficacy of skincare products. Galactomyces ferment filtrate (GFF) is such a functional ingredient. Its use originated from the empirical observation that the hands of sake brewers who deal with yeast fermentation retain a beautiful and youthful appearance. Consequently, skincare products based on GFF are widely used throughout the world. Recent studies have demonstrated that GFF activates an aryl hydrocarbon receptor (AHR) and upregulates the expression of filaggrin, a pivotal endogenous source of natural moisturizing factors, in epidermal keratinocytes. It also activates nuclear factor erythroid-2-related factor 2 (NRF2), the antioxidative master transcription factor, and exhibits potent antioxidative activity against oxidative stress induced by ultraviolet irradiation and proinflammatory cytokines, which also accelerate inflammaging. GFF-mediated NRF2 activation downregulates the expression of CDKN2A, which is known to be overexpressed in senescent keratinocytes. Moreover, GFF enhances epidermal terminal differentiation by upregulating the expression of caspase-14, claudin-1, and claudin-4. It also promotes the synthesis of the antiinflammatory cytokine IL-37 and downregulates the expression of proallergic cytokine IL-33 in keratinocytes. In addition, GFF downregulates the expression of the CXCL14 and IL6R genes, which are involved in inflammaging. These beneficial properties might underpin the potent barrier-protecting and anti-inflammaging effects of GFF-containing skin formulae.

A Systematic Review of Atopic Dermatitis: The Intriguing Journey Starting from Physiopathology to Treatment, from Laboratory Bench to Bedside

Atopic dermatitis (AD) is a common chronic inflammatory and immune-mediated skin disease with a complex pathophysiology and still represents a therapeutic challenge, owing to limited responses to available treatments. However, recent advances in the understanding of AD pathophysiology have led to the discovery of several new potential therapeutic targets, and research in the field of new molecules with therapeutic perspectives is boiling, with more than 70 new promising drugs in development. The aim of this systematic review is to provide the state of the art on the current knowledge concerning the pathophysiology of the disease and on novel agents currently being investigated for AD, and to highlight which type of evolution is going to take place in therapeutic approaches of atopic dermatitis in the coming years.

Elevation of IgE in patients with psoriasis: Is it a paradoxical phenomenon?

Immunoglobulin E (IgE) elevation is a hallmark of allergic conditions such as atopic dermatitis (AD). The pathogenesis of AD is typically associated with high levels of IL-4 and IL-13 produced by activated T helper 2 (Th2) cells. Psoriasis, on the other hand, is an inflammatory skin disease mainly driven by Th17 cells and their related cytokines. Although the immunopathologic reactions and clinical manifestations are often easily distinguished in the two skin conditions, patients with psoriasis may sometimes exhibit AD-like manifestations, such as elevated IgE and persistent pruritic lesions. Given the fact that the effective T cells have great plasticity to re-differentiate in response to innate and environmental factors, this unusual skin condition could be a consequence of a cross-reaction between distinct arms of T-cell and humoral immunity. Here we review the literature concerning the roles of IgE in the development of AD and psoriasis, showing that elevated IgE seems to be an important indicator for this non-typical psoriasis.

Huanglian ointment alleviates eczema by maintaining the balance of c-Jun and JunB and inhibiting AGE-RAGE-mediated pro-inflammation signaling pathway

BACKGROUND

Huanglian ointment exhibits clinical efficacy for repairing skin barriers and inhibiting skin inflammation, and has been used to ameliorate eczema for many years. However, the active components and mechanism of Huanglian ointment have not yet been elucidated.

PURPOSE

This study aimed to demonstrate the main active components and molecular mechanisms of Huanglian ointment for the treatment of eczema.

METHODS

The main active components of Huanglian ointment were identified by gas chromatography-mass spectrometry. Network pharmacology approach and molecular docking techniques to predict the potential molecular mechanisms of Huanglian ointment alleviating eczema. Furthermore, Biostir-AD®-induced guinea pigs and tumor necrosis α (TNF-α)/interferon γ (IFN-γ)-induced HaCaT cells were employed to investigate the effectiveness and mechanisms of Huanglian ointment using histopathological staining, enzyme-linked immunosorbent assay, MTT assay, and western blot analysis.

RESULTS

Fourteen chemistry components were identified in Huanglian ointment. In total, 78 intersecting gene targets were identified between Huanglian ointment and eczema, including Jun, inflammatory regulators, and chemokine factors. Intersecting gene targets were enriched for cytokine and chemokine receptor binding, and inflammatory related signaling pathways. The molecular docking results showed that the identified components had a stable binding conformation with core targets. In vivo experiments showed that Huanglian ointment markedly ameliorated eczema-like skin lesions, restored histopathological morphology, and decreased levels of TNF-α, IFN-γ, and interleukin 6. Moreover, Huanglian ointment effectively protected HaCaT cells against TNF-α/IFN-γ-induced cell death and overproduction of thymus- and activation-regulated chemokine, macrophage-derived chemokine, and regulated upon activation normal T cell-expressed and secreted factor. Subsequently, we found that Huanglian ointment repaired skin barriers by affecting c-Jun, JunB, and filaggrin expression, and suppressed inflammatory response by inhibiting AGE-RAGE signaling pathway, both in vivo and in vitro.

CONCLUSION

Our results demonstrated that Huanglian ointment repaired skin barriers and inhibited inflammation by maintaining the balance of c-Jun and JunB, and suppressing AGE-RAGE signaling pathway, thereby relieving eczema. These findings providing a molecular basis for treatment of eczema by Huanglian ointment.

An evaluation of abrocitinib for moderate-to-severe atopic dermatitis

INTRODUCTION

Atopic dermatitis (AD) is a common itchy inflammatory skin condition that affects many individuals. For many years, the landscape of AD treatment remained unchanged; however, there has been developing therapies that directly target the underlying immunological mechanism of AD. Janus kinase (JAK) inhibitors are small molecules that have shown anti-inflammatory and anti-itch effects in AD. Recently, abrocitinib, an oral JAK 1 inhibitor, was approved by the Food and Drug Administration for atopic dermatitis.

AREAS COVERED

By downregulating the immune cascade, abrocitinib has demonstrated the ability to curb symptoms of AD, including rapidly reducing pruritus in 2-3 days, and is safe and well-tolerated overall despite a low increased risk in infection. The data discussed was obtained from a comprehensive literature review utilizing PubMed.

EXPERT OPINION

Abrocitinib has strong efficacy, likely due to its broader mechanism of action provided by the inhibition of key regulatory molecule, JAK. Results have demonstrated that it is more efficacious at curbing symptoms of AD than dupilumab, the current treatment of choice for refractory, moderate-to-severe AD. While abrocitinib provides a great alternative treatment, particularly for non-responders and AD subtypes, it also demonstrates a stronger side effect profile that must be considered.

Calcium-Based Antimicrobial Peptide Compounds Attenuate DNFB-Induced Atopic Dermatitis-Like Skin Lesions via Th-Cells in BALB/c Mice

Atopic dermatitis (AD) is a chronic and recurrent inflammatory skin disease, characterized by severe itching and recurrent skin lesions. We hypothesized that a novel treatment involving calcium-based antimicrobial peptide compounds (CAPCS), a combination of natural calcium extracted from marine shellfish, and a variety of antimicrobial peptides, may be beneficial for AD. We established a dinitrofluorobenzene (DNFB)-induced AD model in BALB/c mice to test our hypothesis. We observed mouse behavior and conducted histopathological and immunohistochemical analyses on skin lesions before and after CAPCS treatment. We also characterized the changes in the levels of cytokines, inflammatory mediators, and Toll-like receptors (TLRs) in plasma and skin lesions. The results showed that (i) topical application of CAPCS ameliorated AD-like skin lesions and reduced scratching behavior in BALB/c mice; (ii) CAPCS suppressed infiltration of inflammatory cells and inhibited the expression of inflammatory cytokines in AD-like skin lesions; (iii) CAPCS reduced plasma levels of inflammatory cytokines; and (iv) CAPCS inhibited TLR2 and TLR4 protein expression in skin lesions. Topical application of CAPCS exhibits a therapeutic effect on AD by inhibiting inflammatory immune responses via recruiting helper T cells and engaging the TLR2 and TLR4 signaling pathways. Therefore, CAPCS may be useful for the treatment of AD.

Jiu-Wei-Yong-An Formula suppresses JAK1/STAT3 and MAPK signaling alleviates atopic dermatitis-like skin lesions

ETHNOPHARMACOLOGICAL RELEVANCE

Jiu-Wei-Yong-An (JWYA) formula is a traditional Chinese medicine (TCM) prescription used to treat atopic dermatitis (AD) in the clinic. JWYA is considered to have anti-inflammatory and antipruritic properties. However, the mechanism of JWYA remains unclear.

AIM OF THE STUDY

This study aimed to investigate the effect of JWYA on an experimental mouse AD model.

MATERIALS AND METHODS

Mice were sensitized with 2,4-dinitrochlorobenzene (DNCB) and intragastrically administered with JWYA for 14 days. The therapeutic effect was assessed using a grade four dermatitis score, skin moisture, thickness measurements, and a mouse behavior tests. H&E and toluidine blue staining were used to observe epidermal inflammatory thickening and mast cells in mouse skin lesions. Serum IgE levels and skin TNF-α and IL-4 levels were determined using ELISAs. The TNF-α, IL-1β, IL-4, IL-13, IL-31, IL-33, and IFN-γ mRNA expression levels in skin lesions were detected using qPCR. Network pharmacology analysis based on serum active components was performed to elucidate the mechanism, and the results were verified by Western blotting. Finally, we tested the binding affinity between the active ingredients of JWYA and JAK1 via molecular docking.

RESULTS

JWYA improved the skin lesions of AD mice, relieved itching and reduced skin thickening. Additionally, JWYA decreased the serum IgE level and the levels of TNF-α, IL-1β, IL-4, IL-13, IL-31, IL-33, and IFN-γ in skin. Moreover, JWYA inhibited the activation of JAK1/STAT3 and MAPK (p38, ERK, and JNK) signaling. Molecular docking showed that kaempferol, luteolin, and forsythin have high affinity for JAK1.

CONCLUSIONS

JWYA alleviates AD-like skin lesions and inhibited inflammation and skin itch. The effect of JWYA is attributed to blocking the JAK1/STAT3 and MAPK signaling pathways. We suggest that JWYA may be an alternative therapy for the treatment of AD.

Effects of Oral Administration of Lactiplantibacillus Plantarum APsulloc 331261 (GTB1TM) Isolated from Green Tea on Atopic Dermatitis (AD)-like Skin Lesion Mouse Models

Background

Probiotics are known to improve atopic dermatitis (AD) by inhibiting T helper 2 (Th2)-related reactions, restoring the Th2/T helper1 (Th1) cytokine ratio. The most popular probiotic is Lactiplantibacillus plantarum (L. plantarum), which is widely used in the food and pharmaceutical industries. L. plantarum APsulloc 331261 (GTB1) used in this study was isolated from green tea.

Materials and Methods

The effectiveness of oral GTB1 administration in improving AD was evaluated by visual evaluation, comparison of the lymph node sizes and spleen weights, histological evaluation, RT-qPCR, ELISA, and IHC analysis in the mouse model.

Results

GTB1 improved AD symptoms, reduced epidermal thickness and mast cell numbers, decreased lymph node size and the spleen weight, increased filaggrin and loricrin protein levels, downregulated Th2 expression, and upregulated Th1 expression in a colony-forming unit-dependent manner.

Conclusion

Oral administration of GTB1 isolated from green tea (Camellia sinensis) improved the AD symptoms, reduced hypersensitivity reaction, and increased the skin barrier function. Finally, it is involved in AD improvement by restoring the Th2/Th1 cytokine balance.

What's New in Topicals for Atopic Dermatitis?

Atopic dermatitis (AD) is a chronic inflammatory skin condition that can have tremendous impact on quality of life for affected children and adults. First-line therapy for acute management of AD includes topical therapies such as corticosteroids, calcineurin inhibitors, and, more recently, the phosphodiesterase inhibitor crisaborole. Topical agents have remained the mainstay therapy for decades; however, there has been a longstanding need for topical therapies with high efficacy and low risk of adverse effects with long-term use. Given the ongoing advances in understanding the pathogenesis of AD, there are novel targets for pharmacological intervention. We are now in an unprecedented time with more than 40 topical treatments in the pipeline for AD in addition to many developments and treatments on the horizon. This review summarizes selected therapeutic topical agents in later phases of development that target various aspects in the pathogenesis of AD such as Janus kinase inhibition (ruxolitinib and delgocitinib), phosphodiesterase-4 inhibition (roflumilast and difamilast), aryl hydrocarbon modulation (tapinarof), and modulation of the microbiome. We also review novel targeted therapies that are in early phase clinical trials, including AMTX-100, BEN-2293, and PRN473. Preliminary findings on efficacy and tolerability of most of these agents are promising, but further studies are warranted to evaluate the long-term safety and efficacy of these novel agents against the current standard of care.

3-Bromo-4,5-dihydroxybenzaldehyde Isolated from Polysiphonia morrowii Suppresses TNF-α/IFN-γ-Stimulated Inflammation and Deterioration of Skin Barrier in HaCaT Keratinocytes

Polysiphonia morrowii is a well-known red alga that has promising pharmacological characteristics. The current study evaluates the protective effect of 3-bromo-4,5-dihydroxybenzaldehyde (BDB) isolated from P. morrowii on tumor necrosis factor (TNF)-α/interferon (IFN)-γ-stimulated inflammation and skin barrier deterioration in HaCaT keratinocytes. The anti-inflammatory effect of BDB in TNF-α/IFN-γ-stimulated HaCaT keratinocytes is evaluated by investigating nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, inflammatory cytokines, and chemokines. Further, the interaction between BDB and the skin barrier functions in stimulated HaCaT keratinocytes is investigated. The findings of the study reveal that BDB dose-dependently increases cell viability while decreasing intracellular reactive oxygen species (ROS) production. BDB downregulates the expression of inflammatory cytokines, interleukin (IL)-6, -8, -13, IFN-γ, TNF-α, and chemokines, Eotaxin, macrophage-derived chemokine (MDC), regulated on activation, normal T cells expressed and secreted (RANTES), and thymus and activation-regulated chemokine (TARC) by modulating the MAPK and NF-κB signaling pathways in TNF-α/IFN-γ-stimulated HaCaT keratinocytes. Furthermore, BDB increases the production of skin hydration proteins and tight junction proteins in stimulated HaCaT keratinocytes by preserving skin moisturization and tight junction stability. These findings imply that BDB exhibits a protective ability against inflammation and deterioration of skin barrier via suppressing the expression of inflammatory signaling in TNF-α/IFN-γ-stimulated HaCaT keratinocytes.

Potential Therapeutic Skin Microbiomes Suppressing Staphylococcus aureus-Derived Immune Responses and Upregulating Skin Barrier Function-Related Genes via the AhR Signaling Pathway

Disruption of the skin microbial balance can exacerbate certain skin diseases and affect prognosis and treatment. Changes in the distribution and prevalence of certain microbial species on the skin, such as Staphylococcus aureus (SA), can impact the development of severe atopic dermatitis (AD) or psoriasis (Pso). A dysfunctional skin barrier develops in AD and Pso due to SA colonization, resulting in keratinization and chronic or progressive chronic inflammation. Disruption of the skin barrier following SA colonization can elevate the production of T helper 2 (Th2)-derived cytokines, which can cause an imbalance in Th1, Th2, and Th17 cells. This study examined the ability of potential therapeutic skin microbiomes, such as Cutibacterium avidum R-CH3 and Staphylococcus hominis R9, to inhibit SA biofilm formation and restore skin barrier function-related genes through the activation of the aryl hydrocarbon receptor (AhR) and the nuclear factor erythroid-2-related factor 2 (Nrf2) downstream target. We observed that IL-4/IL-13-induced downregulation of FLG, LOR, and IVL induced by SA colonization could be reversed by dual AhR/Nrf2 activation. Further, OVOL1 expression may be modulated by functional microbiomes via dual AhR/Nrf2 activation. Our results suggest that our potential therapeutic skin microbiomes can prevent SA-derived Th2-biased skin barrier disruption via IL-13 and IL-4-dependent FLG deregulation, STAT3 activation, and AhR-mediated STAT6 expression.

Galectin-9 contributes to the pathogenesis of atopic dermatitis via T cell immunoglobulin mucin-3

Background

Atopic dermatitis (AD), a common type 2 inflammatory disease, is driven by T helper (T_H) 2/T_H22polarization and cytokines.Galectin-9 (Gal-9), via its receptor T cell immunoglobulin- and mucin-domain-containing molecule-3 (TIM-3), can promote T_H2/T_H22 immunity. The relevance of this in AD is largely unclear.

Objectives

To characterize the role of TIM-3 and Gal-9 in the pathogenesis of AD and underlying mechanisms.

Methods

We assessed the expression of Gal-9 and TIM-3 in 30 AD patients, to compare them with those of 30 healthy controls (HC) and to explore possible links with disease features including AD activity (SCORAD), IgE levels, and circulating eosinophils and B cells. We also determined the effects of Gal-9 on T cells from the AD patients.

Results

Our AD patients had markedly higher levels of serum Gal-9 and circulating TIM-3-expressing T_H1 and T_H17 cells than HC. Gal-9 and TIM-3 were linked to high disease activity, IgE levels, and circulating eosinophils and/or B cells. The rates of circulating TIM-3-positive CD4⁺ cells were positively correlated with rates of T_H2/T_H22 cells and negatively correlated with rates of T_H1/T_H17 cells. Gal-9 inhibited the proliferation and induced the apoptosis of T cells in patients with AD, especially in those with severe AD.

Conclusion

Our findings suggest thatGal-9, via TIM-3, contributes to the pathogenesis of AD by augmenting T_H2/T_H22 polarization through the downregulation of T_H1/T_H17immunity. This makes Gal-9 and TIM-3 interesting to explore further, as possible drivers of disease and targets of novel AD treatment.

Screening and Research on Skin Barrier Damage Protective Efficacy of Different Mannosylerythritol Lipids

Mannosylerythritol lipids (MELs) may prevent skin barrier damage, although their protective mechanisms and active monomeric constituents remain unclear. Here, three MELs were extracted from Candida antarctica cultures containing fermented olive oil then purified using silica gel-based column chromatography and semipreparative HPLC. All three compounds (MEL-A, MEL-B, MEL-C) were well separated and stable, and reliable materials were used for NMR and HRESIMS chemical structure determinations and for assessing MELs’ protective effects against skin damage. Notably, MEL-B and MEL-C effectively protected HaCaT cells from UVB-induced damage by upregulating the contents of filaggrin (FLG) and transglutaminase-1 (TGM1), as determined via ELISA. Moreover, MEL-B treatment (20 μg/mL) of UVB-irradiated HaCaT cells led to the upregulation of both the expression of mRNA genes and the key proteins FLG, LOR, and TGM1, which are known to be decreased in damaged skin cells. Additionally, histopathological analysis results revealed a markedly reduced intracellular vacuolation and cell damage, reflecting improved skin function after MEL-B treatment. Furthermore, immunofluorescence results revealed that MEL-B protected EpiKutis^® three-dimensional cultured human skin cells from sodium dodecyl sulfate-induced damage by up-regulating FLG, LOR, and TGM1 expression. Accordingly, MELs’ protection against skin barrier damage depended on MEL-B monomeric constituent activities, thus highlighting their promise as beneficial ingredients for use in skin-care products.

Esophageal Mucosal Permeability as a Surrogate Measure of Cure in Eosinophilic Esophagitis

This study aimed to evaluate the relationship of esophageal epithelial permeability with mast cell infiltration and IgG4 deposits as well as chemokine levels in eosinophilic esophagitis (EoE) patients before and after treatment. Biopsies from controls and EoE patients before and after treatment were analyzed. Hematoxylin and eosin staining was used to show eosinophil infiltration. Paracellular permeability of the esophageal epithelium was assessed using surface biotinylation. Immunohistochemical staining was performed to examine mast cell infiltration and IgG4 deposits. Gene expression of chemokines was evaluated by qRT-PCR. Esophageal epithelial infiltration of mast cells, IgG4 deposits, and permeability were significantly increased in EoE patients. Levels of interleukin-13, calpain-14, and eotaxin-3 mRNAs were significantly upregulated, while filaggrin, serine peptidase inhibitor Kazal type 7 (SPINK7), and involucrin mRNAs were significantly downregulated in EoE patients. In patients achieving histologic remission diagnosed by eosinophil counts, a subset of EoE patients with unchanged permeability after treatment showed increases in mast cell infiltration, IgG4 deposits, and interleukin-13, calpain-14, filaggrin, and SPINK7 expression, with decreased eotaxin-3 and involucrin. Other EoE patients with decreased permeability displayed decreased eotaxin-3, involucrin, and mast cell infiltration, no IgG4 deposits, and increased IL-13, calpain-14, filaggrin, and SPINK7. Increased permeability of the esophagus in EoE patients without eosinophil infiltration after treatment was associated with mast cell infiltration and IgG4 deposits.

Alginate nanocapsules by water-in-oil emulsification and external gelation for drug delivery to fine dust stimulated keratinocytes

Methodologies for synthesizing drug-loaded alginate nanocapsules were optimized and indomethacin and phloroglucinol loading capacities were studied. Their biological effects were studied for ameliorating fine dust (FD) induced detrimental effects in keratinocytes. The 1 % alginate to oil phase ratio of 1:20 was the optimal parameter for water in oil emulsification. The oil phase was optimized to contain sunflower oil: span 80 ratios of 17:3. Nanocapsule drug encapsulation efficiencies were 36.91 ± 5.56 and 32.41 ± 4.05 % respectively for phloroglucinol (EG2P) and indomethacin (EG2I) while the loading capacities were 25.28 ± 3.36 and 23.15 ± 2.84 %. Dried nanocapsules indicated a 40-140 nm diameter range while their hydrodynamic diameter was 989.69 nm at pH 7.0. Nanocapsules swelling was pH-dependent and in releasing media of pH values 4.5, 7.4, and 8.5, the drug release indicated a complex mechanism of swelling, diffusion, and erosion while at pH 2.0 the drug release followed the non-Fickian release. EG2P and EG2I treatment dose-dependently lowered FD-induced intracellular ROS production, apoptosis and inflammatory responses mediated through the NF-κB pathway in FD stimulated HaCaT keratinocytes and reduced epidermal barrier degradation. Further research could investigate the use of this technique in formulating cosmeceuticals containing drug-loaded alginate nanocapsules for achieving controlled release.

The contribution of mouse models to understanding atopic dermatitis

Atopic dermatitis (AD) is a dermatological disease accompanied by dry and cracked skin with severe pruritus. Although various therapeutic strategies have been introduced to alleviate AD, it remains challenging to cure the disorder. To achieve such a goal, understanding the pathophysiological mechanisms of AD is a prerequisite, requiring mouse models that properly reflect the AD phenotypes. Currently, numerous AD mouse models have been established, but each model has its own advantages and weaknesses. In this review, we categorized and summarized mouse models of AD and described their characteristics from a researcher's perspective.

Limosilactobacillus reuteri Attenuates Atopic Dermatitis via Changes in Gut Bacteria and Indole Derivatives from Tryptophan Metabolism

Gut bacteria are closely associated with the development of atopic dermatitis (AD) due to their immunoregulatory function. Indole derivatives, produced by gut bacteria metabolizing tryptophan, are ligands to activate the aryl hydrocarbon receptor (AHR), which plays a critical role in attenuating AD symptoms. Limosilactobacillus reuteri, a producer of indole derivatives, regulates mucosal immunity via activating the AHR signaling pathway. However, the effective substance and mechanism of L. reuteri in the amelioration of AD remain to be elucidated. In this research, we found that L. reuteri DYNDL22M62 significantly improved AD-like symptoms in mice by suppressing IgE levels and the expressions of thymic stromal lymphopoietin (TSLP), IL-4, and IL-5. L. reuteri DYNDL22M62 induced an increase in the production of indole lactic acid (ILA) and indole propionic acid (IPA) via targeted tryptophan metabolic analysis and the expression of AHR in mice. Furthermore, L. reuteri DYNDL22M62 increased the proportions of Romboutsia and Ruminococcaceae NK4A214 group, which were positively related to ILA, but decreased Dubosiella, which was negatively related to IPA. Collectively, L. reuteri DYNDL22M62 with the role of modulating gut bacteria and the production of indole derivatives may attenuate AD via activating AHR in mice.

Distribution of Cannabinoid Receptors in Keratinocytes of Healthy Dogs and Dogs With Atopic Dermatitis

It is commonly accepted that some form of skin barrier dysfunction is present in canine atopic dermatitis (AD), one of the most common cutaneous pruritic inflammatory diseases of dogs. The impaired skin barrier function facilitates the penetration of allergens and subsequently stronger sensitization responses. The role of the endocannabinoid system (ECS) in the physiology and pathology of the skin is becoming increasingly established. It has been demonstrated that cannabinoid receptors are expressed in healthy and diseased skin and, based on current knowledge, it could be stated that cannabinoids are important mediators in the skin. The present study has been designed to immunohistochemically investigate the expression of the cannabinoid receptors type 1 (CB1R) and 2 (CB2R) and the cannabinoid-related receptors G protein-coupled receptor 55 (GPR55), transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1), peroxisome proliferator-activated receptors alpha (PPARα), and serotoninergic receptor 1a (5-HT1aR) in keratinocytes of healthy dogs and of dogs with AD. Samples of skin tissues were collected from 7 healthy controls (CTRL-dogs) and from 8 dogs with AD (AD-dogs). The tissue samples were processed using an immunofluorescence assay with commercially available antibodies, and the immunolabelling of the receptors studied was quantitatively evaluated. The keratinocytes of the CTRL- and the AD-dogs showed immunoreactivity for all the receptors investigated with a significant upregulation of CB2R, TRPA1, and 5-HT1aR in the epidermis of the AD-dogs. The presence of cannabinoid and cannabinoid-related receptors in healthy keratinocytes suggested the possible role of the ECS in canine epidermal homeostasis while their overexpression in the inflamed tissues of the AD-dogs suggested the involvement of the ECS in the pathogenesis of this disease, having a possible role in the related skin inflammation and itching. Based on the present findings, the ECS could be considered a potential therapeutic target for dogs with AD.

Current and Emerging Strategies to Inhibit Type 2 Inflammation in Atopic Dermatitis

Type 2 immunity evolved to combat helminth infections by orchestrating a combined protective response of innate and adaptive immune cells and promotion of parasitic worm destruction or expulsion, wound repair, and barrier function. Aberrant type 2 immune responses are associated with allergic conditions characterized by chronic tissue inflammation, including atopic dermatitis (AD) and asthma. Signature cytokines of type 2 immunity include interleukin (IL)-4, IL-5, IL-9, IL-13, and IL-31, mainly secreted from immune cells, as well as IL-25, IL-33, and thymic stromal lymphopoietin, mainly secreted from tissue cells, particularly epithelial cells. IL-4 and IL-13 are key players mediating the prototypical type 2 response; IL-4 initiates and promotes differentiation and proliferation of naïve T-helper (Th) cells toward a Th2 cell phenotype, whereas IL-13 has a pleiotropic effect on type 2 inflammation, including, together with IL-4, decreased barrier function. Both cytokines are implicated in B-cell isotype class switching to generate immunoglobulin E, tissue fibrosis, and pruritus. IL-5, a key regulator of eosinophils, is responsible for eosinophil growth, differentiation, survival, and mobilization. In AD, IL-4, IL-13, and IL-31 are associated with sensory nerve sensitization and itch, leading to scratching that further exacerbates inflammation and barrier dysfunction. Various strategies have emerged to suppress type 2 inflammation, including biologics targeting cytokines or their receptors, and Janus kinase inhibitors that block intracellular cytokine signaling pathways. Here we review type 2 inflammation, its role in inflammatory diseases, and current and future therapies targeting type 2 pathways, with a focus on AD. INFOGRAPHIC.

Differences in Behavior between Normal and Atopic Keratinocytes in Culture: Pilot Studies

Skin barrier dysfunction is important in atopic dermatitis and can be secondary to inflammation. Observation of keratinocytes in culture may show intrinsic differences. TransEpithelial Electrical Resistance (TEER) measures epithelial permeability. We cultured normal and atopic keratinocytes and found that TEER of atopic keratinocytes was significantly lower (p < 0.0001) than that of normals. Atopic keratinocytes grew upwards, first creating isolated dome-like structures and later horizontally into a monolayer. At time of confluence (D0), atopic keratinocytes were more differentiated, with higher filaggrin gene expression than normals. No differences existed between groups for TJ proteins (claudin, occludin, and Zonula Occludens-1) on D0 and D6. On D6, claudin and occludin were higher than D0, in normal (p = 0.0296 and p = 0.0011) and atopic keratinocytes (p = 0.0348 and 0.0491). Immunofluorescent staining showed nuclear location of filaggrin on D0 and cytoplasmic on D6. ANOVA showed increased cell size from D0 to D6 in both groups (effect of time, p = 0.0076) but no differences between groups. Significant subject effect (p = 0.0022) was found, indicating that cell size was subject-dependent but not disease-dependent. No difference for continuity for TJ protein existed between groups. These observations suggest that decreased TEER in atopics is not linked to TJ differences but is possibly linked to different growth behavior.

Effects of Spore-Displayed p75 Protein from Lacticaseibacillus rhamnosus GG on the Transcriptional Response of HT-29 Cells

A Lacticaseibacillus rhamnosus GG-derived protein, p75, is one of the key molecules exhibiting probiotic activity. However, the molecular mechanism and transcriptional response of p75 in human intestinal epithelial cells are not completely understood. To gain a deeper understanding of its potential probiotic action, this study investigated genome-wide responses of HT-29 cells to stimulation by spore-displayed p75 (CotG-p75) through a transcriptome analysis based on RNA sequencing. Analysis of RNA-seq data showed significant changes of gene expression in HT-29 cells stimulated by CotG-p75 compared to the control. A total of 189 up-regulated and 314 down-regulated genes was found as differentially expressed genes. Gene ontology enrichment analysis revealed that a large number of activated genes was involved in biological processes, such as epithelial cell differentiation, development, and regulation of cell proliferation. A gene–gene interaction network analysis showed that several DEGs, including AREG, EREG, HBEGF, EPGN, FASLG, GLI2, CDKN1A, FOSL1, MYC, SERPINE1, TNFSF10, BCL6, FLG, IVL, SPRR1A, SPRR1B, SPRR3, and MUC5AC, might play a critical role in these biological processes. RNA-seq results for selected genes were verified by reverse transcription-quantitative polymerase chain reaction. Overall, these results provide extensive knowledge about the transcriptional responses of HT-29 cells to stimulation by CotG-p75. This study showed that CotG-p75 can contribute to cell survival and epithelial development in human intestinal epithelial cells.

Managing Atopic Dermatitis with Lebrikizumab - The Evidence to Date

Atopic dermatitis is a prevalent, inflammatory skin disease that presents with an eczematous, itchy rash. As of late, there have been many emerging monoclonal antibody inhibitor and small molecule therapies that have changed the course of eczema treatment. One of the treatments in the pipeline for atopic dermatitis is interleukin 13 monoclonal antibody inhibitor, lebrikizumab. As interleukin 13 has been identified as a pro-inflammatory cytokine in the immunological cascade of eczema, it is thought that lebrikizumab can be a great treatment choice for patients with atopic dermatitis. Lebrikizumab is currently being investigated in several studies. Thus far, lebrikizumab for the treatment of eczema has been found to be efficacious; in particular, a rapid response of pruritus improvement has been demonstrated in as early as 2 days. Additionally, it is well tolerated and has an acceptable safety profile, with reports suggesting that are decreased risks of infection when compared to dupilumab. In this review, we aim to summarize the current understanding of lebrikizumab in terms of the mechanism of action, preclinical pharmacology, pharmacokinetics and metabolism, efficacy and safety, and drug indications.

Atopic Dermatitis: Sailing beyond the Sunset with a Multitude of Novel Treatments

Atopic eczema or dermatitis (AD) is a chronic pruritic inflammatory cutaneous disorder with an incidence up to 20% in children and 10% in adults depending on region and ethnicity [...].

Immunological Pathomechanisms of Spongiotic Dermatitis in Skin Lesions of Atopic Dermatitis

Atopic dermatitis (AD) is a chronic pruritic skin disease with a complex pathogenesis underlying its heterogeneous clinical phenotypes and endotypes. The skin manifestation of AD reflects the cytokine milieu of a type-2-dominant immunity axis induced by genetic predisposition, innate immunity dysregulation, epidermal barrier defects, and allergic inflammation. However, the detailed pathomechanism of eczematous dermatitis, which is the principal characteristic of AD, remains unclear. This review examines previous studies demonstrating research progress in this area and considers the immunological pathomechanism of “spongiotic dermatitis”, which is the histopathological hallmark of eczematous dermatitis. Studies in this field have revealed the importance of IgE-mediated delayed-type hypersensitivity, the Fas/Fas-ligand system, and cell-mediated cytotoxicity in inducing the apoptosis of keratinocytes in spongiotic dermatitis. Recent studies have demonstrated that, together with infiltrating CD4 T cells, IgE-expressing dendritic cells (i.e., inflammatory dendritic epidermal cells and Langerhans cells) that capture specific allergens (i.e., house dust mites) are present in the spongiotic epidermis of lichenified eczema in patients with IgE-allergic AD. These findings suggest that IgE-mediated delayed-type hypersensitivity plays a pivotal role in the pathogenesis of spongiotic dermatitis in the skin lesions of AD.

Skin Care Product Rich in Antioxidants and Anti-Inflammatory Natural Compounds Reduces Itching and Inflammation in the Skin of Atopic Dermatitis Patients

The atopic dermatitis (AD) complex pathogenesis mechanism reveals marked changes of certain signaling factors as well as some morphological alterations in the epidermis. Reduced resilience against environmental factors and oxidative stress often makes the treatment with corticosteroids or tacrolismus ointments indispensable. In view of the correlation between oxidative stress and AD pathological factors, antioxidants can be incorporated into AD management strategies. This study investigates a curly kale, apple and green tea-containing natural extract rich in antioxidants for its effects on signaling inflammatory molecules and skin barrier enhancement in human epidermal keratinocytes- (NHEKs) based cell assays. Furthermore, the skin penetration on porcine ears was measured ex vivo using Raman micro spectroscopy. Finally, in a double-blind half-side, placebo-controlled clinical study, the effects of a formulation containing this extract were analyzed for the influence of lesion severity, epidermal barrier function, and pruritus in mild to moderately AD patients. Summarizing our results: The extract reduces expression of inflammatory cytokines in keratinocytes and increases barrier-related molecules. The verum formulation with a very high antioxidant capacity used in AD patients with mild to moderate lesions reduces itching, local SCORAD, and improves barrier function and the hydration of skin lesions.

Role of Basophils in a Broad Spectrum of Disorders

Basophils are the rarest granulocytes and have long been overlooked in immunological research due to their rarity and similarities with tissue-resident mast cells. In the last two decades, non-redundant functions of basophils have been clarified or implicated in a broad spectrum of immune responses, particularly by virtue of the development of novel analytical tools for basophils. Basophils infiltrate inflamed tissues of patients with various disorders, even though they circulate in the bloodstream under homeostatic conditions. Depletion of basophils results in the amelioration or exaggeration of inflammation, depending on models of disease, indicating basophils can play either beneficial or deleterious roles in a context-dependent manner. In this review, we summarize the recent findings of basophil pathophysiology under various conditions in mice and humans, including allergy, autoimmunity, tumors, tissue repair, fibrosis, and COVID-19. Further mechanistic studies on basophil biology could lead to the identification of novel biomarkers or therapeutic targets in a broad range of diseases.