The Role of TSLP in Atopic Dermatitis: From Pathogenetic Molecule to Therapeutical Target

Phase 1 Safety and Pharmacokinetics Study of TAVO101, an Anti-Human Thymic Stromal Lymphopoietin Antibody for the Treatment of Allergic Inflammatory Conditions

TAVO101 is a humanized anti-human thymic stromal lymphopoietin (TSLP) monoclonal antibody under clinical development for the treatment of atopic dermatitis (AD) and other allergic inflammatory conditions. The crystallizable fragment region of the antibody was engineered for half-life extension and attenuated effector functions. This Phase 1, double-blinded, randomized, placebo-controlled study assessed the safety, tolerability, pharmacokinetics, and immunogenicity of TAVO101 in healthy adult subjects in seven ascending dose cohorts. Subjects received a single intravenous administration of TAVO101 or placebo with a 195-day follow-up. TAVO101 was safe and well tolerated. The incidences and severities of treatment-emergent adverse events were mostly mild and comparable between the active and placebo groups, with no trends of dose relationship. There were no severe adverse events, deaths, or treatment-related withdrawals. TAVO101 exhibited a linear pharmacokinetic profile, low clearance, and a median elimination half-life of 67 days in healthy subjects. All TAVO101-treated subjects tested negative for anti-drug antibodies. To support development in AD, TAVO101 was studied in an oxazolone-induced AD model in hTSLP transgenic mice and demonstrated efficacy. This long-acting anti-TSLP antibody has the potential for stronger and sustained allergic inflammatory disease control. The results from this study warranted further clinical development of TAVO101 in patients.

The involvement of keratinocytes in pruritus of chronic inflammatory dermatosis

Frequent itching and incessant scratching are commonly observed in various chronic inflammatory skin conditions, including atopic dermatitis and psoriasis. The persistent and prolonged nature of pruritus can worsen one's quality of life. Keratinocytes (KCs), the predominant cells of the epidermis, have been confirmed to interact with sensory neurons and immune cells and be involved in chronic skin inflammatory diseases associated with pruritus. Initially, KCs and sensory neurons form a unique synapse-like connection within the epidermis, serving as the structural foundation for their interaction. Additionally, several receptors, including toll-like receptors and protease-activated receptor 2, expressed on KCs, become activated in an inflammatory milieu. On the one hand, activated KCs are sources of pro-inflammatory cytokines and neurotrophic factors, such as adenosine triphosphate, thymic stromal lymphopoietin, and nerve growth factor, which directly or indirectly participate in stimulating sensory neurons, thereby contributing to the itch sensations. On the other hand, KCs also function as primary transducers alongside intraepidermal nerve endings, directly initiating pruritic responses. This review summarizes the current literature and highlights the critical role of KCs in the development and persistence of chronic itch in inflammatory skin disorders.

MRGPRX2 antagonist GE1111 attenuated DNFB-induced atopic dermatitis in mice by reducing inflammatory cytokines and restoring skin integrity

Introduction

Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterised by itching, erythema, and epidermal barrier dysfunction. The pathogenesis of AD is complex and multifactorial; however,mast cell (MC) activation has been reported to be one of the crucial mechanisms in the pathogenesis of AD. The MC receptor Mas related G protein-coupled receptor-X2 (MRGPRX2) has been identified as a prominent alternative receptor to the IgE receptor in causing MC activation and the subsequent release of inflammatory mediators. The current study aimed to evaluate the therapeutic effect of a novel small molecule MRGPRX2 antagonist GE1111 in AD using in vitro and in vivo approaches.

Methods

We developed an in vitro cell culture disease model by using LAD-2 MC, HaCaT keratinocytes and RAW 264.7 macrophage cell lines. We challenged keratinocytes and macrophage cells with CST-14 treated MC supernatant in the presence and absence of GE1111 and measured the expression of tight junction protein claudin 1, inflammatory cytokines and macrophage phagocytosis activity through immunohistochemistry, western blotting, RT-qPCR and fluorescence imaging techniques. In addition to this, we developed a DFNB-induced AD model in mice and evaluated the protective effect and underlying mechanism of GE1111.

Results and Discussion

Our in vitro findings demonstrated a potential therapeutic effect of GE1111, which inhibits the expression of TSLP, IL-13, MCP-1, TNF-a, and IL-1ß in MC and keratinocytes. In addition to this, GE1111 was able to preserve the expression of claudin 1 in keratinocytes and the phagocytotic activity of macrophage cells. The in vivo results demonstrated that GE1111 treatment significantly reduced phenotypic changes associated with AD (skin thickening, scaling, erythema and epidermal thickness). Furthermore, immunohistochemical analysis demonstrated that GE1111 treatment preserved the expression of the tight junction protein Involucrin and reduced the expression of the inflammatory mediator periostin in the mouse model of AD. These findings were supported by gene and protein expression analysis, where GE1111 treatment reduced the expression of TSLP, IL-13, and IL-1ß, as well as downstream signalling pathways of MRGPRX2 in AD skin lesions. In conclusion, our findings provide compelling in vitro and in vivo evidence supporting the contribution of MRGPRX2-MC interaction with keratinocytes and macrophages in the pathogenesis of AD.

Skin biomarkers predict the development of food allergy in early life

BACKGROUND

Food allergy (FA) often occurs in early childhood with and without atopic dermatitis (AD). FA can be severe and even fatal. For primary prevention, it is important to find early biomarkers to predict the future onset of FA before any clinical manifestations.

OBJECTIVE

Our aim was to find early predictors of future onset of FA in the stratum corneum (SC).

METHODS

Skin tape strips were collected from the forearm of newborns (n = 129) at age 2 months, before any signs of clinical FA or AD. Children were clinically monitored until they reached age 2 years to confirm the presence or absence of FA and AD. Skin tape strips were subjected to lipidomic analyses by liquid chromatography-tandem mass spectrometry and cytokine determination by Meso Scale Discovery U-Plex assay.

RESULTS

Overall, 9 of 129 infants (7.0%) developed FA alone and 9 of 129 infants (7.0%) developed FA concomitantly with AD. In the stratum corneum of children with future FA and concomitant AD and FA, absolute amounts of unsaturated (N24:1)(C18-sphingosine)ceramide and (N26:1)(C18-sphingosine)ceramide and their relative percentages within the molecular group were increased compared with the amounts and percentages in healthy children, with P values ranging from less than .01 to less than .05 according to ANOVA. The children with future AD had normal levels of these molecules. IL-33 level was upregulated in those infants with future FA but not in those with future AD, whereas thymic stromal lymphopoietin was upregulated in those with future AD but not in those with future FA. Logistic regression analysis revealed strong FA predicting power for the combination of dysregulated lipids and cytokines, with an odds ratio reaching 101.4 (95% CI = 5.4-1910.6).

CONCLUSION

Noninvasive skin tape strip analysis at age 2 months can identify infants at risk of FA in the future.

In Vitro Anti-Inflammatory and Skin Protective Effects of Codium fragile Extract on Macrophages and Human Keratinocytes in Atopic Dermatitis

Codium fragile has been traditionally used in oriental medicine to treat enterobiasis, dropsy, and dysuria, and it has been shown to possess many biological properties. Atopic dermatitis (AD) is one of the types of skin inflammation and barrier disruption, which leads to chronic inflammatory skin diseases. In the current investigation, the protective effects of C. fragile extract (CFE) on anti-inflammation and skin barrier improvement were investigated. In LPS-stimulated RAW 264.7 cells, nitric oxide generation and the expression levels of interleukin (IL)-1β, IL-4, IL-6, iNOS, COX-2, and tumor necrosis factor-alpha (TNF)-α were reduced by CFE. CFE also inhibited the phosphorylation of NF-κB-p65, ERK, p-38, and JNK. Additionally, CFE showed inhibitory activity on TSLP and IL-4 expression in HaCaT cells stimulated with TNF-α/interferon-gamma (IFN-γ). Enhanced expression of factors related to skin barrier function, FLG, IVL, and LOR, was confirmed. These findings implied that CFE may be used as a therapeutic agent against AD due to its skin barrier-strengthening and anti-inflammatory activities, which are derived from natural marine products.

CD1a and skin T cells: a pathway for therapeutic intervention

The CD1 and MR1 protein families present lipid antigens and small molecules to T cells, complementing well-studied major histocompatibility complex-peptide mechanisms. The CD1a subtype is highly and continuously expressed within the skin, most notably on Langerhans cells, and has been demonstrated to present self and foreign lipids to T cells, highlighting its cutaneous sentinel role. Alteration of CD1a-dependent T-cell responses has recently been discovered to contribute to the pathogenesis of several inflammatory skin diseases. In this review, we overview the structure and role of CD1a and outline the current evidence implicating CD1a in the development of psoriasis, atopic dermatitis and allergic contact dermatitis.

Precision Dermatology: A Review of Molecular Biomarkers and Personalized Therapies

The evolution of personalized medicine in dermatology signifies a transformative shift towards individualized treatments, driven by the integration of biomarkers. These molecular indicators serve beyond diagnostics, offering insights into disease staging, prognosis, and therapeutic monitoring. Specific criteria guide biomarker selection, ensuring attributes like specificity, sensitivity, cost feasibility, stability, rapid detection, and reproducibility. This literature review, based on data from PubMed, SCOPUS, and Web of Science, explores biomarkers in Hidradenitis Suppurativa (HS), Psoriasis, Atopic Dermatitis (AD), Alopecia Areata (AA), Vitiligo, and Chronic Spontaneous Urticaria (CSU). In HS, TNF-α, IL-1β, and MMPs serve as biomarkers, influencing targeted therapies like adalimumab and anakinra. Psoriasis involves biomarkers such as TNF-α, IL-23, and HLA genes, shaping treatments like IL23 and IL17 inhibitors. AD biomarkers include ECP, IL-4, IL-13, guiding therapies like dupilumab and tralokinumab. For AA, lipocalin-2, cytokines, and genetic polymorphisms inform JAK inhibitors' use. Vitiligo biomarkers range from cytokines to genetic markers like TYR, TYRP1, guiding treatments like JAK inhibitors. CSU biomarkers encompass IgE, cytokines, and autologous serum tests, influencing therapies like omalizumab and cyclosporine. Comparing conditions, common proinflammatory markers reveal limited specificity. While some biomarkers aid diagnosis and standard treatments, others hold more scientific than clinical value. Precision medicine, driven by biomarkers, has shown success in skin malignancies. Future directions involve AI-powered algorithms, nanotechnology, and multi-omics integration for personalized dermatological care.

Immunomodulatory and anti-angiogenesis effects of excavatolide B and its derivatives in alleviating atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin condition primarily driven by T helper 2 (Th2) cytokines, resulting in skin barrier defects, angiogenesis, and inflammatory responses. The marine natural product excavatolide B (EXCB), isolated from the Formosan Gorgonian coral Briareum stechei, exhibits anti-inflammatory and analgesic properties. To enhance solubility, EXCB is chemically modified into the derivatives EXCB-61 salt and EXCB-79. The study aims to investigate the therapeutic effects of these compounds on dinitrochlorbenzene (DNCB)-induced skin damage and to elucidate the underlying anti-inflammatory and anti-angiogenesis mechanism. In vitro, using lipopolysaccharide (LPS)-induced RAW 264.7 cells, all compounds at 10 μM significantly inhibited expression of inflammatory proteins (inducible nitric oxide synthase and cyclooxygenase-2), vascular endothelial growth factor (VEGF), and cytokines (interleukin (IL)-1β, IL-6, and IL-17A). In vivo, topical application of these compounds on DNCB-induced AD mice alleviated skin symptoms, reduced serum levels of IgE, IL-4, IL-13, IL-17, and interferon-γ, and moderated histological phenomena such as hyperplasia, inflammatory cell infiltration, and angiogenesis. The three compounds restored the expression of skin barrier-related proteins (loricrin, filaggrin, and claudin-1) and reduced the expression of angiogenesis-related proteins (VEGF and platelet endothelial cell adhesion molecule-CD31) in the tissues. This is the first study to indicate that EXCB, EXCB-61 salt, and EXCB-79 can treat AD disease by reducing inflammation and angiogenesis. Hence, they may be considered potential candidates for the development of new drugs for AD.

The last step to achieve barrier damage control

Heterogeneity characterises inflammatory diseases and different phenotypes and endotypes have been identified. Both innate and adaptive immunity contribute to the immunopathological mechanism of these diseases and barrier damage plays a prominent role triggering type 2 inflammation through the alarmins system, such as anti-Thymic Stromal Lymphopoietin (TSLP). Treatment with anti-TSLP monoclonal antibodies showed efficacy in severe asthma and clinical trials for other eosinophilic diseases are ongoing. The aim of this perspective review is to analyse current advances and future applications of TSLP inhibition to control barrier damage.

Role of IL-4 and IL-13 in Cutaneous T Cell Lymphoma

The interleukins IL-4 and IL-13 are increasingly recognized contributors to the pathogenesis of cutaneous T cell lymphomas (CTCLs), and their role in disease-associated pruritus is accepted. The prevailing Th2 profile in advanced CTCL underscores the significance of understanding IL-4/IL-13 expression dynamics from the early stages of disease, as a shift from Th1 to Th2 may explain CTCL progression. Targeted agents blocking key cytokines of type 2 immunity are established therapeutics in atopic disorders and have a promising therapeutic potential in CTCL, given their involvement in cutaneous symptoms and their contribution to the pathogenesis of disease. IL-4, IL-13, and IL-31 are implicated in pruritus, offering therapeutic targets with dupilumab, tralokinumab, lebrikizumab, and nemolizumab. This review analyzes current knowledge on the IL-4/IL-13 axis in mycosis fungoides and Sezary syndrome, the most common types of CTCL, examining existing literature on the pathogenetic implications with a focus on investigational treatments. Clinical trials and case reports are required to shed light on novel uses of medications in various diseases, and ongoing research into the role of IL-4/IL-13 axis blockers in CTCL therapy might not only improve the management of disease-related pruritus but also provide in-depth insights on the pathophysiologic mechanisms of CTCL.

TRPV1 Channel in Human Eosinophils: Functional Expression and Inflammatory Modulation

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

Effectiveness of switching from baricitinib 4 mg to upadacitinib 30 mg in patients with moderate-to-severe atopic dermatitis: a real-world clinical practice in Japan

BACKGROUND

Atopic dermatitis (AD) is a chronic eczematous disease with severe pruritus. Janus kinase (JAK) inhibitors, upadacitinib, baricitinib, and abrocitinib, are systemic treatments for AD. The outcomes of switching from one JAK inhibitor to another have not been examined.

OBJECTIVES

We assessed the outcomes of switching from baricitinib 4 mg to upadacitinib 30 mg in Japanese patients with moderate-to-severe AD.

METHODS

Twenty patients treated with baricitinib 4 mg, showing insufficient response or adverse events, were switched to treatment with upadacitinib 30 mg. We evaluated total eczema area and severity index (EASI), EASI at head and neck, trunk, upper, or lower limbs, EASI of erythema, edema/papulation, excoriation, or lichenification, and peak pruritus numerical-rating scale (PP-NRS) at baseline (start of baricitinib), weeks 0 (time of switching), and 4 and 12 after switching.

RESULTS

Total EASI, EASI at each anatomical site, EASI of each clinical sign, and PP-NRS were markedly reduced at weeks 4 or 12 compared to week 0. Achievement rates of more than 75% or 90% reduction of EASI from baseline significantly improved after switching.

CONCLUSIONS

Switching from baricitinib 4 mg to upadacitinib 30 mg effectively improved rash and pruritus.

Esculentoside A ameliorates DNCB-induced atopic dermatitis by suppressing the ROS-NLRP3 axis via activating the Nrf2 pathway

Atopic dermatitis (AD) is a chronic inflammatory skin condition with a high prevalence. Inflammation and oxidative stress are strongly associated with AD progression. Esculentoside A (EsA) inhibits inflammation and oxidative stress in various diseases. However, whether EsA mitigates AD by suppressing inflammation and oxidative stress remains unknown. A mouse model of AD was constructed by the induction of 1-chloro-2,4-dinitrochlorobenzene (DNCB). The mechanism of EsA and its effects on AD symptoms, pathology, inflammation and oxidative stress were investigated through histopathological staining, enzyme-linked immunosorbent assay, blood cells analysis, colorimetric measurement and western blot analysis. EsA improved the clinical symptoms and increased clinical skin scores in AD mice. Skin thickening of the epidermis and dermal tissues and the mast cell numbers in AD mice were reduced with the EsA treatment. EsA decreased the relative mRNA level of thymic stromal lymphopoietin, interleukin (IL)-4, IL-5 and IL-13; the serum concentrations of immunoglobulin E (IgE) and IL-6; and the numbers of white blood cells (WBC) and WBC subtypes, including basophil, lymphocytes, eosinophil, neutrophil and monocytes in DNCB-induced mice. DNCB caused higher levels of oxidative stress, which was reversed with the administration of EsA. Mechanically, EsA upregulated the expression of Nrf2 but downregulated the level of NLRP3 inflammasome in AD mice. The inhibitor of Nrf2 significantly recovered the EsA-induced changes in the NLRP3 inflammasome proteins in DNCB-treated mice. Therefore, EsA improved the clinical and pathological symptoms, inflammation and oxidative stress experienced by DNCB-induced mice and was involved in the inactivation of NLRP3 inflammasome by activating Nrf2.

Thymic Stromal Lymphopoietin (TSLP), Its Isoforms and the Interplay with the Epithelium in Allergy and Asthma

Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine that has emerged as a critical player in the development and progression of allergy and asthma. It is primarily produced by epithelial cells and functions as a potent immune system activator. TSLP acts through interaction with its receptor complex, composed of the TSLP receptor (TSLPR) and interleukin-7 receptor alpha chain (IL-7Rα), activating downstream complex signalling pathways. The TSLP major isoform, known as long-form TSLP (lfTSLP), is upregulated in the airway epithelium of patients with allergic diseases. More research is warranted to explore the precise mechanisms by which short-form TSLP (sfTSLP) regulates immune responses. Understanding the dynamic interplay between TSLP and the dysfunctional epithelium provides insights into the mechanisms underlying allergy and asthma pathogenesis. Targeting TSLP represents an important therapeutic strategy, as it may upstream disrupt the inflammatory cascade and alleviate symptoms associated with allergic inflammation.

Challenges and Future Trends in Atopic Dermatitis

Atopic dermatitis represents a complex and multidimensional interaction that represents potential fields of preventive and therapeutic management. In addition to the treatment armamentarium available for atopic dermatitis, novel drugs targeting significant molecular pathways in atopic dermatitis biologics and small molecules are also being developed given the condition's complex pathophysiology. While most of the patients are expecting better efficacy and long-term control, the response to these drugs would still depend on numerous factors such as complex genotype, diverse environmental triggers and microbiome-derived signals, and, most importantly, dynamic immune responses. This review article highlights the challenges and the recently developed pharmacological agents in atopic dermatitis based on the molecular pathogenesis of this condition, creating a specific therapeutic approach toward a more personalized medicine.