IL-4 receptor alpha blockade dampens allergic inflammation and upregulates IL-17A expression to promote Saureus clearance in antigen sensitized mouse skin

Low Infection Rates With Long-Term Dupilumab Treatment in Patients Aged 6 Months to 5 Years: An Open-Label Extension Study

OBJECTIVE

To evaluate long-term infection rates in children aged 6 months to 5 years with moderate-to-severe atopic dermatitis (AD) treated with dupilumab.

METHODS

This was a post hoc analysis of an ongoing open-label extension (OLE) study of dupilumab. Pediatric patients aged 6 months to 5 years with moderate-to-severe AD who had previously taken part in the LIBERTY AD PRESCHOOL phase 2 and 3 clinical trials received weight-based subcutaneous dupilumab every 2 or 4 weeks. Exposure-adjusted infection rates after a median dupilumab exposure of 52 weeks are compared with data from the earlier randomized, placebo-controlled, 16-week LIBERTY AD PRESCHOOL phase 3 trial.

RESULTS

Infection rates were overall lower in the OLE study compared with the dupilumab and placebo groups in the earlier 16-week trial, including total infections (101.0 patients/100 patient-years [PY]), nonherpetic skin infections (22.7 patients/100PY), herpetic infections (7.3 patients/100PY), and nonskin infections (92.9 patients/100PY). The frequency of severe and serious infections was low (3.1 patients/100PY), compared with 17.1 placebo-treated patients/100PY and 0 dupilumab-treated patients in the earlier 16-week trial, and no infections leading to treatment discontinuation were observed. Systemic anti-infective medication use (58.9 patients/100PY) was lower in the OLE study compared with both the dupilumab and placebo groups in the 16-week trial.

CONCLUSION

Overall, reduced infection rates are observed in infants and young children with moderate-to-severe AD treated with dupilumab long-term, supporting the known safety profile of dupilumab.

Rocaglamide Suppresses Allergic Reactions by Regulating IL-4 Receptor Signaling

Rocaglamide (Roc-A), a natural phytochemical isolated from Aglaia species, is known to exert anticancer effects. Allergic inflammation can enhance the tumorigenic potential of cancer cells. We hypothesized that Roc-A could regulate allergic inflammation. Roc-A prevented an antigen from increasing the hallmarks of allergic reactions in vitro. Roc-A suppressed passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA). RNA sequencing analysis showed that Roc-A prevented the antigen from increasing the expression of IL-4 in RBL2H3 cells. Roc-A also prevented the antigen from increasing the expression of interleukin-4 receptor (IL-4R). Roc-A was found to form a hydrogen-bonding network with residues N92 and L64 of IL-4R in a molecular docking simulation. Roc-A prevented the antigen from inducing the binding of IL-4R to JAK1. Chromatin immunoprecipitation (ChIP) assays showed that C-Jun could bind to promoter sequences of IL-4 and IL-4R. Mouse recombinant IL-4 protein increased β-hexosaminidase activity, IL-4R expression, and the hallmarks of allergic inflammation in the antigen-independent manner. Mouse recombinant IL-4 protein increased the expressions of CD163 and arghinase-1 and markers of M2 macrophages, but decreased the expression of iNOS, a marker of M1 macrophages in lung macrophages. Roc-A regulated the effects of a culture medium of antigen-stimulated RBL2H3 cells on the expressions of iNOS and arginase-1 in RAW264.7 macrophages. The blocking of IL-4 or downregulation of IL-4R exerted negative effects on the hallmarks of allergic reactions in vitro. The blocking of IL-4 or downregulation of IL-4R also exerted negative effects on PCA, and the downregulation of IL-4R exerted negative effects on PSA. An miR-34a mimic exerted negative effects on allergic reactions in vitro. The downregulation of IL-4R prevented the antigen from decreasing the expression of miR-34a in RBL2H3 cells. We identified chemicals that could bind to IL-4R via molecular docking analysis. The IL-4R docking chemical 1536801 prevented the antigen from increasing β-hexosaminidase activity and the hallmarks of allergic reactions. The IL-4R docking chemical 1536801 also exerted a negative effect on PCA. TargetScan analysis predicted miR-34a as a negative regulator of IL-4R. We found that the anti-allergic effect of Roc-A and its mechanisms were associated with miR-34a. Taken together, our results show that understanding IL-4R-mediated allergic reactions can provide clues for the development of anti-allergy therapeutics.

Skin microbiota: pathogenic roles and implications in atopic dermatitis

Atopic dermatitis (AD) is a chronic and inflammatory skin disorder characterized by impaired barrier function and imbalanced immunity. Recent advances have revealed that dysbiosis of skin microbiota plays important roles in the pathogenesis and development of AD. Meanwhile, endogenous and external factors contribute to the dysbiosis of skin microbiota in AD. Additionally, various treatments, including topical treatments, phototherapy, and systemic biologics, have demonstrated positive impacts on the clinical outcomes, alongside with the modulations of cutaneous microbiota in AD patients. Importantly, therapeutics or products regulating skin microbiota homeostasis have demonstrated potential for AD treatment in early clinical studies. In this review, we underline changes of the skin microbiota correlated with AD. Meanwhile, we provide an overview of the skin microbiota regarding its roles in the pathogenesis and development of AD. Finally, we summarize therapeutic strategies restoring the skin microbial homeostasis in AD management.

Aloe-emodin relieves allergic contact dermatitis pruritus by inhibiting mast cell degranulation

Urushiol-induced allergic contact dermatitis (ACD) is a chronic inflammatory skin disease in which skin barrier dysfunction leads to pruritus and eczematous lesions. ACD is triggered by immune imbalance. Aloe emodin is an anthraquinone derivative extracted from rhubarb, aloe and other traditional Chinese medicines. It has a wide range of pharmacological effects, including anti-inflammatory, anti-tumor, and anti-allergic effects. The purpose of our study was to demonstrate the effectiveness of aloe-emodin on urushiol-induced acute pruritus and allergic contact dermatitis. The results showed that urushiol could stimulate keratinocytes to release chemokines CXCL1, CXCL2, CCL2, TSLP, and TNF-α, which recruit or activate mast cells. Aloe-emodin treatment inhibited inflammatory-response-induced mast cell degranulation in skin lesions and suppressed the expression of inflammatory cytokines, such as interleukin-4, and interleukin-6. Therefore, the results indicate that aloe-emodin can improve urushiol-induced acute pruritus and allergic contact dermatitis in mice by inhibiting mast cell degranulation.

Vasoactive Intestinal Peptide Receptor, CRTH2, Antagonist Treatment Improves Eosinophil and Mast Cell-Mediated Esophageal Remodeling and Motility Dysfunction in Eosinophilic Esophagitis

BACKGROUND AND AIMS

Ultrasonography has shown that eosinophils accumulate in each segment of the esophageal mucosa in human EoE, ultimately promoting esophageal motility dysfunction; however, no mechanistic evidence explains how or why this accumulation occurs.

METHODS

Quantitative PCR, ELISA, flow cytometry, immunostaining, and immunofluorescence analyses were performed using antibodies specific to the related antigens and receptors.

RESULTS

In deep esophageal biopsies of EoE patients, eosinophils and mast cells accumulate adjacent to nerve cell-derived VIP in each esophageal segment. qRT-PCR analysis revealed five- to sixfold increases in expression levels of VIP, CRTH2, and VAPC2 receptors and proteins in human blood- and tissue-accumulated eosinophils and mast cells. We also observed a significant correlation between mRNA CRTH2 levels and eosinophil- and nerve cell-derived VIPs in human EoE (p < 0.05). We provide evidence that eosinophil and mast cell deficiency following CRTH2 antagonist treatment improves motility dysfunction in a chronic DOX-inducible CC10-IL-13 murine model of experimental EoE.

CONCLUSIONS

CRTH2 antagonist treatment is a novel therapeutic strategy for inflammatory cell-induced esophageal motility dysfunction in IL-13-induced chronic experimental EoE.

Rapid reduction in Staphylococcus aureus in atopic dermatitis subjects following dupilumab treatment

BACKGROUND

Atopic dermatitis (AD) is an inflammatory disorder characterized by dominant type 2 inflammation leading to chronic pruritic skin lesions, allergic comorbidities, and Staphylococcus aureus skin colonization and infections. S aureus is thought to play a role in AD severity.

OBJECTIVES

This study characterized the changes in the host-microbial interface in subjects with AD following type 2 blockade with dupilumab.

METHODS

Participants (n = 71) with moderate-severe AD were enrolled in a randomized (dupilumab vs placebo; 2:1), double-blind study at Atopic Dermatitis Research Network centers. Bioassays were performed at multiple time points: S aureus and virulence factor quantification, 16s ribosomal RNA microbiome, serum biomarkers, skin transcriptomic analyses, and peripheral blood T-cell phenotyping.

RESULTS

At baseline, 100% of participants were S aureus colonized on the skin surface. Dupilumab treatment resulted in significant reductions in S aureus after only 3 days (compared to placebo), which was 11 days before clinical improvement. Participants with the greatest S aureus reductions had the best clinical outcomes, and these reductions correlated with reductions in serum CCL17 and disease severity. Reductions (10-fold) in S aureus cytotoxins (day 7), perturbations in TH17-cell subsets (day 14), and increased expression of genes relevant for IL-17, neutrophil, and complement pathways (day 7) were also observed.

CONCLUSIONS

Blockade of IL-4 and IL-13 signaling, very rapidly (day 3) reduces S aureus abundance in subjects with AD, and this reduction correlates with reductions in the type 2 biomarker, CCL17, and measures of AD severity (excluding itch). Immunoprofiling and/or transcriptomics suggest a role for TH17 cells, neutrophils, and complement activation as potential mechanisms to explain these findings.