Administration of poly(I:C) improved dermatophagoides farinae-induced atopic dermatitis-like skin lesions in NC/Nga mice by the regulation of Th1/Th2 balance

miRNAs' Cross-Involvement in Skin Allergies: A New Horizon for the Pathogenesis, Diagnosis and Therapy of Atopic Dermatitis, Allergic Contact Dermatitis and Chronic Spontaneous Urticaria

Skin inflammation is a common underlying feature of atopic dermatitis, allergic contact dermatitis and chronic spontaneous urticaria. The pathogenetic mechanisms have not been fully elucidated. The purpose of this study was to examine whether miRNA, by regulating inflammatory mechanisms through the modulation of innate and adaptive immune responses, could play a major role in the pathogenesis of these skin conditions. We conducted a narrative review using the Pubmed and Embase scientific databases and search engines to find the most relevant miRNAs related to the pathophysiology, severity and prognosis of skin conditions. The studies show that miRNAs are involved in the pathogenesis and regulation of atopic dermatitis and can reveal an atopic predisposition or indicate disease severity. In chronic spontaneous urticaria, different miRNAs which are over-expressed during urticaria exacerbations not only play a role in the possible response to therapy or remission, but also serve as a marker of chronic autoimmune urticaria and indicate associations with other autoimmune diseases. In allergic contact dermatitis, miRNAs are upregulated in inflammatory lesions and expressed during the sensitization phase of allergic response. Several miRNAs have been identified as potential biomarkers of these chronic skin conditions, but they are also possible therapeutic targets.

Gardenia jasminoides extract without crocin improved atopic dermatitis-like skin lesions via suppression of Th2-related cytokines in Dfe-induced NC/Nga mice

ETHNOPHARMACOLOGICAL RELEVANCE

Atopic dermatitis (AD) is a pruritic, chronic, relapsing inflammatory skin disease. Gardenia jasminoides extract (GJE) has been used as a traditional remedy for the treatment of various inflammatory diseases, including AD. The specific effects of the extract components, which include crocin, geniposidic acid, and gardenoside, on inflammatory responses in AD are not entirely clear.

AIM OF THE STUDY

We determined the effects of G. jasminoides extract with crocin removed (GJE-C) on AD-like skin lesions in Dermatophagoies farina crude extract (Dfe)-treated NC/Nga mice, a well-known AD mouse model.

MATERIALS AND METHODS

To prepare the mice, 150 μl of 4% sodium dodecyl sulfate (SDS) was applied to the shaved dorsal skin or ear of NC/Nga mice 1 h before application of 100 mg Dfe. After 7 d, GJE-C was applied every day for 14 d. We performed behavior, histological, ELISA, assays to evaluate chemokines, cytokines, and skin barrier proteins in skin or serum samples from treated and untreated NC/Nga mice.

RESULTS

Topical application of GJE-C improved the severity scores of the AD-like skin lesions, frequency of scratching, and ear swelling in Dfe-treated NC/Nga mice similar to the complete GJE. In addition, GJE-C also reduced serum IgE and chemokine levels as well as the inflammatory response. Topical application of GJE-C also resulted in decreased infiltration of inflammatory cells, such as mast cells, via reduction of Th2 inflammatory mediators, including interleukin (IL)-4, IL-5, and IL-13, pro-inflammatory cytokines, and chemokines, and increased skin barrier protein expression in Dfe-treated NC/Nga mice. The GJE components geniposidic acid and gardenoside inhibited the production of atopic-related chemokines in HaCaT cells, but inclusion of crocin dampened this inhibition of chemokine production.

CONCLUSIONS

Together, these findings indicate that GJE-C may improve AD-like lesions by inhibiting the Th2 inflammatory response and expression of chemokines while increasing the expression of skin barrier proteins. These data provide experimental evidence that GJE-C may harbor therapeutic potential for AD.

Crocin Ameliorates Atopic Dermatitis Symptoms by down Regulation of Th2 Response via Blocking of NF-κB/STAT6 Signaling Pathways in Mice

Crocin, a major constituent of Gardenia jasminoides, is a natural colorant carotenoid compound that has been reported to have anti-inflammatory effects. This study investigated the therapeutic effects of crocin on mice with atopic dermatitis induced by Dermatophagoides farinae crude extract, which is a common environmental allergen in house dust that causes atopic dermatitis in humans. Crocin application ameliorated Dermatophagoides farinae crude extract-induced atopic dermatitis symptoms by inhibiting the dermatitis severity score, ear thickness, and serum immunoglobulin E levels in NC/Nga mice. The increases in epidermal thickness and dermal inflammatory cells (eosinophil and mast cells) infiltrations observed on the dorsal back skin of atopic dermatitis control mice were inhibited in a dose-dependent manner by topical application of crocin in atopic dermatitis treatment mice. Crocin inhibited the Dermatophagoides farinae crude extract-induced increase of thymus and activation-regulated chemokines, interleukin (IL)-4, and IL-13 on the dorsal skin of mice. Crocin also inhibited Dermatophagoides farinae crude extract-induced activation of nuclear factor-κB (NF-κB) and signal transducer and activator of transcription (STAT) 6. These results show that crocin ameliorates atopic dermatitis symptoms by down regulation of the Th2 cells-mediated immune response via blocking of NF-κB/STAT6 signaling pathways.

Regulation of Allergic Immune Responses by Microbial Metabolites

Emerging evidence demonstrates that the microbiota plays an essential role in shaping the development and function of host immune responses. A variety of environmental stimuli, including foods and commensals, are recognized by the host through the epithelium, acting as a physical barrier. Two allergic diseases, atopic dermatitis and food allergy, are closely linked to the microbiota, because inflammatory responses occur on the epidermal border. The microbiota generates metabolites such as short-chain fatty acids and poly-γ-glutamic acid (γPGA), which can modulate host immune responses. Here, we review how microbial metabolites can regulate allergic immune responses. Furthermore, we focus on the effect of γPGA on allergic T helper (Th) 2 responses and its therapeutic application.

MiR-151a is involved in the pathogenesis of atopic dermatitis by regulating interleukin-12 receptor β2

MicroRNAs (miRNAs) have been reported to circulate in the blood in a highly stable and cell-free form. Dysregulated expression of miRNAs has been detected in various pathological conditions including atopic dermatitis. In our study, human blood plasma miRNAs were identified by high-throughput sequencing and compared among patients of atopic dermatitis and healthy controls. We found that miR-151a was differentially expressed in the plasma of atopic dermatitis patients. MiR-151a regulates the expression of IL12RB2 by targeting two loci in the 3' untranslated region of the Il12rb2 gene. Moreover, IL12RB2 was remarkably downregulated in Jurkat cells overexpressing miR-151a. Jurkat cells treated with phytohemagglutinin also showed reduced expression of IFN-γ, interleukin-2 (IL-2) and IL-12. Together, these results suggest that miR-151a is involved in the pathogenesis of atopic dermatitis by regulating IL12RB2.

Regulatory effect of TLR3 signaling on staphylococcal enterotoxin-induced IL-5, IL-13, IL-17A and IFN-γ production in chronic rhinosinusitis with nasal polyps

BACKGROUND

Toll-like receptor 3 (TLR3) is expressed in upper airways, however, little is known regarding whether Toll-like receptor 3 (TLR3) signals exert a regulatory effect on the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP), especially on eosinophilic inflammation. We sought to investigate the effect of Poly(IC), the ligand for TLR3, on cytokine production by dispersed nasal polyp cells (DNPCs).

METHODS

DNPCs were pretreated with or without Poly(IC), and were then cultured in the presence or absence of staphylococcal enterotoxin B (SEB), following which the levels of IL-5, IL-10, IL-13, IL-17A and interferon (IFN)-γ in the supernatant were measured. To determine the involvement of IL-10 and cyclooxygenase in Poly(IC)-mediated signaling, DNPCs were treated with anti-IL-10 monoclonal antibody and diclofenac, the cyclooxygenase inhibitor, respectively. Poly(IC)-induced prostaglandin E2 (PGE2) production was also determined.

RESULTS

Exposure to Poly(IC) induced a significant production of IL-10, but not of IL-5, IL-13, IL-17A or IFN-γ by DNPCs. Pretreatment with Poly(IC) dose-dependently inhibited SEB-induced IL-5, IL-13 and IL-17A, but not IFN-γ production. Neutralization of IL-10 significantly abrogated the inhibitory effect of Poly(IC). Treatment with diclofenac also abrogated the inhibitory effect of Poly(IC) on SEB-induced IL-5 and IL-13 production. However, unlike exposure of diclofenac-treated DNPCs to lipopolysaccharide, the ligand for TLR4, exposure of these cells to Poly(IC) did not enhance IL-5 or IL-13 production. Poly(IC) did not significantly increase PGE2 production by DNPCs.

CONCLUSIONS

These results suggest that TLR3 signaling regulates eosinophilia-associated cytokine production in CRSwNP, at least in part, via IL-10 production.

Coriander alleviates 2,4-dinitrochlorobenzene-induced contact dermatitis-like skin lesions in mice

Contact dermatitis (CD) is a pattern of inflammatory responses in the skin that occurs through contact with external factors. The clinical picture is a polymorphic pattern of skin inflammation characterized by a wide range of clinical features, including itching, redness, scaling, and erythema. Coriandrum sativum L. (CS), commonly known as coriander, is a member of the Apiaceae family and is cultivated throughout the world for its nutritional and culinary values. Linoleic acid and linolenic acid in CS have various pharmacological activities. However, no study of the inhibitory effects of CS on CD has been reported. In this study, we demonstrated the protective effect of CS against 2,4-dinitrochlorobenzene-induced CD-like skin lesions. CS, at doses of 0.5-1%, applied to the dorsal skin inhibited the development of CD-like skin lesions. Moreover, the Th2-mediated inflammatory cytokines, immunoglobulin E, tumor necrosis factor-α, interferon-γ, interleukin (IL)-1, IL-4, and IL-13, were significantly reduced. In addition, CS increased the levels of total glutathione and heme oxygenase-1 protein. Thus, CS can inhibit the development of CD-like skin lesions in mice by regulating immune mediators and may be an effective alternative therapy for contact diseases.

Resiquimod and polyinosinic-polycytidylic acid formulation with aluminum hydroxide as an adjuvant for foot-and-mouth disease vaccine

Background

Toll-like receptor (TLR) agonists reportedly have potent antiviral and antitumor activities and may be a new kind of adjuvant for enhancing immune efficacy. Resiquimod (R848) is an imidazoquinoline compound with potent antiviral activity and functions through the TLR7/TLR8 MyD88-dependent signaling pathway. Polyinosinic-polycytidylic acid [poly(I:C)] is a synthetic analog of double-stranded RNA that induces the production of pro-inflammatory cytokines by the activation of NF-κB through TLR3. This study investigated the potential of R848 and poly(I:C) as an adjuvant 146S foot-and-mouth disease virus (FMDV) vaccine formulated with aluminum hydroxide (Al(OH)₃).

Results

Antibody titers to FMDV and CD8⁺ T cells were markedly enhanced in mice immunized to 146S FMDV + Al(OH)₃ + R848 + poly(I:C) compared with mice immunized to FMDV + ISA206. IFN-γ secretion substantially increased compared with IL-4 secretion by splenic T cells stimulated with FMDV antigens in vitro, suggesting that R848, poly(I:C), and with Al(OH)₃ together biased the immune response toward a Th1-type direction.

Conclusions

These results indicated that the R848 and poly(I:C) together with Al(OH)₃ enhanced humoral and cellular immune responses to immunization with 146S FMDV antigens. Thus, this new vaccine formulation can be used for FMDV prevention.

A toll-like receptor 3 ligand enhances protective effects of vaccination against Marek's disease virus and hinders tumor development in chickens

Marek's disease (MD) is caused by Marek's disease virus (MDV). Various vaccines including herpesvirus of turkeys (HVT) have been used to control this disease. However, HVT is not able to completely protect against very virulent strains of MDV. The objective of this study was to determine whether a vaccination protocol consisting of HVT and a Toll-like receptor (TLR) ligand could enhance protective efficacy of vaccination against MD. Hence, chickens were immunized with HVT and subsequently treated with synthetic double-stranded RNA polyriboinosinic polyribocytidylic [poly(I:C)], a TLR3 ligand, before or after being infected with a very virulent strain of MDV. Among the groups that were HVT-vaccinated and challenged with MDV, the lowest incidence of tumors was observed in the group that received poly(I:C) before and after MDV infection. Moreover, the groups that received a single poly(I:C) treatment either before or after MDV infection were better protected against MD tumors compared to the group that only received HVT. No association was observed between viral load, as determined by MDV genome copy number, and the reduction in tumor formation. Overall, the results presented here indicate that poly(I:C) treatment, especially when it is administered prior to and after HVT vaccination, enhances the efficacy of HVT vaccine and improves protection against MDV.