Calycosin alleviates allergic contact dermatitis by repairing epithelial tight junctions via down-regulating HIF-1α.

Calycosin, a bioactive component derived from Astragali Radix (AR; Huang Qi), has been shown to have an effect of anti-allergic dermatitis with unknown mechanism. This study aims to investigate the mechanism of calycosin related to tight junctions (TJs) and HIF-1α both in FITC-induced mice allergic contact dermatitis and in IL-1ß stimulated HaCaT keratinocytes. Th2 cytokines (IL-4, IL-5 and IL-13) were detected by ELISA. The epithelial TJ proteins (occludin, CLDN1 and ZO-1), initiative key cytokines (TSLP and IL-33) and HIF-1α were assessed by Western blot, real-time PCR, immunohistochemistry or immunofluorescence. Herein, we have demonstrated that allergic inflammation and the Th2 cytokines in ACD mice were reduced significantly by calycosin treatment. Meanwhile, calycosin obviously decreased the expression of HIF-1α and repaired TJs both in vivo and in vitro. In HaCaT keratinocytes, we noted that IL-1ß induced the deterioration of TJs, as well as the increased levels of TSLP and IL-33, which could be reversed by silencing HIF-1α. In addition, administration of 2-methoxyestradiolin (2-ME), a HIF-1α inhibitor,significantly repaired the TJs and alleviated the allergic inflammation in vivo. Furthermore, TJs were destroyed by DMOG or by overexpressing HIF-1α in HaCaT keratinocytes, and simultaneously, calycosin down-regulated the expression of HIF-1α and repaired the TJs in this process. These results revealed that calycosin may act as a potential anti-allergy and barrier-repair agent via regulating HIF-1α in AD and suggested that HIF-1α and TJs might be possible therapy targets for allergic dermatitis.

Formononetin attenuated allergic diseases through inhibition of epithelial-derived cytokines by regulating E-cadherin.

Radix Astragali, has long been used to alleviate allergic diseases (ADs). Formononetin is one of the major active components in Radix Astragali, but its mechanism on ADs is not definitively known. The fluorescein isothiocyanate isomer-induced atopic contact dermatitis mouse model and poly I:C or lipopolysaccharide-treated HaCaT cells were used to examine thymic stromal lymphopoietin (TSLP)/interleukin (IL)-33 production and expression of E-cadherin. After administration of formononetin, TSLP/IL-33 levels decreased both in vitro and in vivo, while E-cadherin was increased in vivo and restored in vitro. Furthermore, small interference RNA silencing of E-cadherin resulted in elevated levels of TSLP, whereas the inhibitory effect of formononetin on TSLP was no longer observed. In addition, TSLP resulted in no detectable changes in delocalization or protein expression of E-cadherin in HaCaT cells. These results indicated that formononetin showed a protective effect in ADs, which was correlated with decreasing TSLP/IL-33 production via regulation of E-cadherin.

Multimodal, broadly neutralizing antibodies against SARS-CoV-2 identified by high-throughput native pairing of BCRs from bulk B cells.

TruAB Discovery is an approach that integrates cellular immunology, high-throughput immunosequencing, bioinformatics, and computational biology in order to discover naturally occurring human antibodies for prophylactic or therapeutic use. We adapted our previously described pairSEQ technology to pair B cell receptor heavy and light chains of SARS-CoV-2 spike protein-binding antibodies derived from enriched antigen-specific memory B cells and bulk antibody-secreting cells. We identified approximately 60,000 productive, in-frame, paired antibody sequences, from which 2,093 antibodies were selected for functional evaluation based on abundance, isotype and patterns of somatic hypermutation. The exceptionally diverse antibodies included RBD-binders with broad neutralizing activity against SARS-CoV-2 variants, and S2-binders with broad specificity against betacoronaviruses and the ability to block membrane fusion. A subset of these RBD- and S2-binding antibodies demonstrated robust protection against challenge in hamster and mouse models. This high-throughput approach can accelerate discovery of diverse, multifunctional antibodies against any target of interest.

EGFR activation-induced decreases in claudin1 promote MUC5AC expression and exacerbate asthma in mice.

Claudin1 plays a critical role in maintaining the epithelial barrier, and mucus hypersecretion induced by epidermal growth factor receptor (EGFR) activation is a pivotal pathological feature of asthma. The relationship between claudin1 expression and mucus hypersecretion and EGFR activation is still poorly understood. In this report, we showed that claudin1 expression correlated with asthma stage, in both patients with asthma and in the house dust mite (HDM)-induced mouse asthma model. Claudin1 knockdown induced MUC5AC overexpression both in 16HBE cells and in mouse airways. In addition, claudin1 expression negatively correlated with asthma severity as demonstrated by significantly higher MUC5AC expression, more severe airway inflammation, and increased airway hyperreactivity in mouse lungs with claudin1 knockdown following HDM challenge. EGFR activation reduced claudin1 expression and increased MUC5AC expression, both in vitro and in vivo. Erlotinib alleviated murine allergic airway inflammation, restored claudin1 expression and decreased MUC5AC expression. These results suggest that EGFR activation-induced decreases in claudin1 promote goblet-cell metaplasia, and restoring claudin1 to maintain barrier integrity by EGFR antagonism may provide a novel therapeutic strategy for asthma.

Frontline Science: Two flavonoid compounds attenuate allergic asthma by regulating epithelial barrier via G protein-coupled estrogen receptor: Probing a possible target for allergic inflammation.

Allergic asthma is a common chronic lung inflammatory disease and seriously influences public health. We aim to investigate the effects of formononetin (FMN) and calycosin (CAL), 2 flavonoids in Radix Astragali, on allergic asthma and elucidate possible therapeutic targets. A house dust mite (HDM)-induced allergic asthma mouse model and TNF-α and Poly(I:C) co-stimulated human bronchial epithelial cell line (16HBE) were performed respectively in vivo and in vitro. The role of G protein-coupled estrogen receptor (GPER) was explored by its agonist, antagonist, or GPER small interfering RNA (siGPER). E-cadherin, occludin, and GPER were detected by western blotting, immunohistochemistry, or immunofluorescence. The epithelial barrier integrity was assessed by trans-epithelial electric resistance (TEER). Cytokines were examined by enzyme-linked immunosorbent assay (ELISA). The results showed that flavonoids attenuated pulmonary inflammation and hyperresponsiveness in asthmatic mice. These flavonoids significantly inhibited thymic stromal lymphopoietin (TSLP), increased occludin and restored E-cadherin in vivo and in vitro. The effects of flavonoids on occludin and TSLP were not interfered by ICI182780 (estrogen receptor antagonist), while blocked by G15 (GPER antagonist). Furthermore, compared with PPT (ERα agonist) and DPN (ERß agonist), G1 (GPER agonist) significantly inhibited TSLP, up-regulated occludin, and restored E-cadherin. siGPER and TEER assays suggested that GPER was pivotal for the flavonoids on the epithelial barrier integrity. Finally, G1 attenuated allergic lung inflammation, which could be abolished by G15. Our data demonstrated that 2 flavonoids in Radix Astragali could alleviate allergic asthma by protecting epithelial integrity via regulating GPER, and activating GPER might be a possible therapeutic strategy against allergic inflammation.

MicroRNA-155-5p is a key regulator of allergic inflammation, modulating the epithelial barrier by targeting PKIα.

Recent studies have demonstrated that microRNA-155-5p (miR-155-5p) plays an essential role in the regulation of allergen-induced inflammation and is overexpressed in the skin of patients with atopic dermatitis (AD), although the mechanism is unknown. In this study, silencing miR-155-5p attenuated the thickening of the epidermis in AD model and reduced the infiltration of inflammatory cells and the secretion of Th2 cytokines. Protein kinase inhibitor α (PKIα) was identified as a direct target of miR-155-5p and correlated negatively with miR-155-5p in our AD model. Fluorescence in situ hybridization showed that miR-155-5p-expressing cells were predominantly present in the epidermis. When epithelial cells were transfected with an miR-155-5p inhibitor, the expression of PKIα, occludin, and CLDN16 increased and that of TSLP decreased significantly, whereas the overexpression of miR-155-5p resulted in the opposite changes. The increased expression of PKIα and tight junction (TJ) proteins, with reduced TSLP and IL-33, was also detected in miR-155-5p-blocked mice, in both the initial and elicitation stages of AD. The expression of TJ proteins also decreased when cells were transfected with PKIα siRNA. TJ proteins increased and TSLP and IL-33 decreased significantly after the overexpression of PKIα. Our data provide the first evidence that miR-155-5p is critical for the allergic inflammation in a mouse model of AD by directly regulating PKIα and thus epithelial TJ expression. These findings suggest new therapeutic strategies that target miR-155-5p in patients with allergic disorders.