Therapeutic approach to mite-induced intractable dermatitis using novel immunomodulator FTY720 ointment (fingolimod) in NC/Nga mice

The potential capacities of FTY720: Novel therapeutic functions, targets, and mechanisms against diseases

Fingolimod (FTY720), an antagonist of sphingosine-1-phosphate (S1P), functions by binding to S1P receptors (S1PRs), excluding S1PR2. It received approval from the Food and Drug Administration (FDA) for the treatment of multiple sclerosis (MS) in 2010. As the first non-selective oral agonist for S1PRs, FTY720's diverse and systemic receptor expression often leads to alterations in various signaling pathways and multiple systems, making it a subject of intense research. Recent studies have identified a wide range of novel or potential functions for FTY720 beyond its application in MS. These include effects on the blood-brain barrier (BBB), vascular system, organelles, and cell death, as well as potential applications in organ transplantation, immune disorders, oncological conditions, neurological and psychiatric disorders, viral infections, and hypersensitivity diseases. This paper reviews the novel roles, targets, and mechanisms of FTY720 that hold promise for clinical utility. Additionally, it summarizes FTY720's derivation and development process, the characterization and mechanism of the structure of FTY720-P bound to S1PRs, the clinical safety profile, future challenges, and potential strategies to address them. These insights aim to guide future research and applications of FTY720, maximizing its therapeutic potential.

Sivelestat's effect on Candida albicans water-soluble fraction-induced vasculitis

BACKGROUND

We investigated the efficacy of sivelestat sodium hydrate (SSH) as a treatment for Kawasaki disease, and its pharmacological action sites, in mice with Candida albicans water-soluble fraction-induced vasculitis.

METHODS

Sivelestat sodium hydrate was administered intraperitoneally to Candida albicans water-soluble fraction-induced vasculitis model mice to assess its efficacy in preventing the development of coronary artery lesions based on the degree of inflammatory cell infiltration in the aortic root and coronary arteries (vasculitis score). The pharmacological sites of action were investigated based on changes in neutrophil elastase (NE) and intercellular adhesion molecule 1 (ICAM-1) positive areas, ICAM-1 and tumor necrosis factor-α mRNA expression levels in the upper heart, and the proportion of monocytes in the peripheral blood.

RESULTS

The vasculitis score decreased below the lower limit of the 95% confidence interval of untreated mice in 69% of the SSH-treated mice. The NE- and ICAM-1-positive regions, and the mRNA expression of ICAM-1 and tumor necrosis factor-α were lower in the SSH-treated mice than in the untreated mice. The proportion of monocytes in the peripheral blood was higher in the SSH-treated mice than in the untreated mice, whereas monocyte migration to inflammation areas was suppressed in the SSH-treated mice.

CONCLUSIONS

Our results showed that SSH might prevent the development of coronary artery lesions and ameliorate disease activity. In addition to its NE-inhibitory effect, SSH sites of action may also include monocytes.

Atopic dermatitis: an expanding therapeutic pipeline for a complex disease

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with a complex pathophysiology that underlies a wide spectrum of clinical phenotypes. AD remains challenging to treat owing to the limited response to available therapies. However, recent advances in understanding of disease mechanisms have led to the discovery of novel potential therapeutic targets and drug candidates. In addition to regulatory approval for the IL-4Ra inhibitor dupilumab, the anti-IL-13 inhibitor tralokinumab and the JAK1/2 inhibitor baricitinib in Europe, there are now more than 70 new compounds in development. This Review assesses the various strategies and novel agents currently being investigated for AD and highlights the potential for a precision medicine approach to enable prevention and more effective long-term control of this complex disease.

Recent advances in understanding of the complex phenotype and mechanisms underlying atopic dermatitis (AD) have revealed multiple new potential targets for pharmacological intervention. Here, Bieber reviews therapeutic strategies and assesses the expanding pipeline for the therapy of AD, highlighting the potential for a precision medicine approach to the management of this complex disorder.

Blockage of sphingosine-1-phosphate receptor 2 attenuates 2,4-dinitrochlorobenzene-induced atopic dermatitis in mice

Sphingosine-1-phosphate (S1P) and its receptors have been implicated in functions of Langerhans cells and atopic dermatitis. In this study, we investigated the roles of S1P receptor type 2 (S1P₂) in a mouse model of atopic dermatitis, which was induced by topical application of 2,4-dinitrochlorobenzene (DNCB) on ventral skin on D0, followed by repeated DNCB challenge on both ears from D7 to D49. Wild-type mice with atopic dermatitis displayed severe inflammation and mast cell accumulation in ear tissues and elevated IgE levels in serum. Furthermore, the mice showed significantly increased sizes of draining lymph nodes, high levels of inflammatory cytokines (IL-4, IL-13, IL-17, and IFN-γ) in the ears and lymph nodes and high levels of chemokines CCL17 and CCL22 in ears. Administration of JTE-013, a selective antagonist of S1P₂ (3 mg/kg, i.p, from D19 to D49) before DNCB challenge significantly suppressed DNCB-induced atopic responses in ears and lymph nodes. JTE-013 administration also significantly decreased the lymph nodes sizes, the levels of inflammatory cytokines (IL-4, IL-13, IL-17, and IFN-γ) in the ears and lymph nodes, and the levels of chemokines CCL17 and CCL22 in ears. Furthermore, the inflammatory responses of atopic dermatitis were greatly ameliorated in S1pr2 gene-deficient mice. As CCL17 and CCL22 are CCR4 ligands, acting as Th2-attracting chemokines, we investigated CCL17 and CCL22 expression in bone marrow-derived dendritic cells (BMDCs) from wild-type and S1pr2 gene-deficient mice. Addition of IL-4 (10 ng/mL) markedly increased the levels of CCL17 and CCL22, but IL-4-induced CCL17 and CCL22 expression was significantly blunted in BMDCs from S1pr2 gene-deficient mice. Furthermore, pretreatment with JTE-013 (1-30 μM) dose-dependently suppressed this induction in BMDCs from wild-type mice. Our results demonstrate that blockage of S1P₂ ameliorates not only DNCB-induced atopic dermatitis symptoms but also Th2 cell-attracting capacity of dendritic cells, suggesting S1P₂ as a potential therapeutic target for atopic dermatitis.

Topical Application of S1P2 Antagonist JTE-013 Attenuates 2,4-Dinitrochlorobenzene-Induced Atopic Dermatitis in Mice

Sphingosine-1-phosphate (S1P) and its receptors have been implicated in atopic dermatitis. S1P₂ was found to function as a pro-allergic receptor, while its antagonist JTE-013 was found to suppress allergic asthma in mice. Topical application of JTE-013 has not been investigated in an in vivo model of atopic dermatitis. Therefore, the therapeutic potential of JTE-013 topical application was evaluated by the use of a 2,4-dinitrochlorobenzene (DNCB)-induced atopic dermatitis mouse model. DNCB-induced inflammation and mast cell accumulation in skin tissues were significantly suppressed by topical JTE-013 treatment in BALB/c mice. DNCB-induced increase of lymph nodes sizes and elevated inflammatory cytokines (IL-4, IL-13, IL-17, and IFN-γ) in lymph nodes were also significantly reduced by the JTE-013 treatment. Elevated serum levels of IgE were significantly suppressed by the topical treatment of JTE-013. In summary, the topical treatment of JTE-013 S1P₂ antagonist suppressed DNCB-induced atopic dermatitis symptoms and immune responses. These results suggested JTE-013 as a potential therapeutic agent for atopic dermatitis.

Protective role of 6-formylindolo[3,2-b]carbazole (FICZ), an endogenous ligand for arylhydrocarbon receptor, in chronic mite-induced dermatitis

BACKGROUND

Chronic eczema such as atopic dermatitis imposes significant socio-econo-psychologic burdens on the affected individuals. In addition to conventional topical treatments, phototherapy is recommended for patients with extensive lesions. Although immunosuppression is believed to explain its primary effectiveness, the underlying mechanisms of phototherapy remain unsolved. Ultraviolet irradiation generates various tryptophan photoproducts including 6-formylindolo[3,2-b]-carbazole (FICZ). FICZ is known to be a potent endogenous agonist for aryl hydrocarbon receptor (AHR); however, the biological role of FICZ in chronic eczema is unknown.

OBJECTIVE

To investigate the effect of FICZ on chronic eczema such as atopic dermatitis.

METHODS

We stimulated HaCaT cells and normal human epidermal keratinocytes (NHEKs) with or without FICZ and then performed quantitative reverse transcriptase polymerase chain reaction, immunofluorescence, and siRNA treatment. We used the atopic dermatitis-like NC/Nga murine model and treated the mice for 2 weeks with either Vaseline® as a control, FICZ ointment, or betamethasone 17-valerate ointment. The dermatitis score, transepidermal water loss, histology, and expression of skin barrier genes and proteins were evaluated.

RESULTS

FICZ significantly upregulated the gene expression of filaggrin in both HaCaT cells and NHEKs in an AHR-dependent manner, but did not affect the gene expression of other barrier-related proteins. In addition, FICZ improved the atopic dermatitis-like skin inflammation, clinical scores, and transepidermal water loss in NC/Nga mice compared with those of control mice. On histology, FICZ significantly reduced the epidermal and dermal thickness as well as the number of mast cells. Topical FICZ also significantly reduced the gene expression of Il22.

CONCLUSION

These findings highlight the beneficial role of FICZ-AHR and provide a new strategic basis for developing new drugs for chronic eczema.

Lipid Mediators of Allergic Disease: Pathways, Treatments, and Emerging Therapeutic Targets

Bioactive lipids are critical regulators of inflammation. Over the last 75 years, these diverse compounds have emerged as clinically-relevant mediators of allergic disease pathophysiology. Animal and human studies have demonstrated the importance of lipid mediators in the development of asthma, allergic rhinitis, urticaria, anaphylaxis, atopic dermatitis, and food allergy. Lipids are critical participants in cell signaling events which influence key physiologic (bronchoconstriction) and immune phenomena (degranulation, chemotaxis, sensitization). Lipid-mediated cellular mechanisms including: (1) formation of structural support platforms (lipid rafts) for receptor signaling complexes, (2) activation of a diverse family of G-protein coupled receptors, and (3) mediating intracellular signaling cascades by acting as second messengers. Here, we review four classes of bioactive lipids (platelet activating factor, the leukotrienes, the prostanoids, and the sphingolipids) with special emphasis on lipid synthesis pathways and signaling, atopic disease pathology, and the ongoing development of atopy treatments targeting lipid mediator pathways.