Atopic dermatitis (AD) is a common chronic pruritic inflammatory skin disorder characterized by recurrent eczematous lesions. Interleukin (IL)−33, a cytokine of the IL-1 family, was found to play an important role in the pathogenesis of AD. As a key component of the inflammasome, NLRP3 has been mostly described in myeloid cells that to mediate inflammasome activation conducted proinflammatory cytokine production of the IL-1 family. However, the role of NLRP3 inflammasome in the pathogenesis of AD, as well as IL-33 processing are highly controversial. Whether NLRP3 can mediate IL-33 expression and secretion independently of the inflammasome in the epithelium of AD has remained unclear. In this article, we found the mRNA expression ofIl33andNlrp3were notably increased in the lesional skin of AD patients compared to healthy controls. We then found a significant positive correlation between the expression ofNlrp3andIl33in the epithelium of MC903-mediated AD mice model, but no changes were observed forIl36α,Il36γ,Il1β, orIl18mRNA expression, as well as IL-1β or IL-18 production. Overexpression of NLRP3 in human immortalized epithelial cells increased IL-33 expression, whereas siRNA targeting NLRP3 abolished IL-33 expression. In addition, inhibition of NLRP3 inflammasome activation or caspase-1 activity with MCC950 or VX-765 showed no effect on the expression and secretion of IL-33 in AD mice. Unlike myeloid cells, NLRP3 predominantly located in the nucleus of epithelial cells, which could directly bind toIl33specific-promoters and transactivate it through an interaction with transcription factor IRF4. Furthermore, NLRP3 deficient mice exhibited a significant alleviated epidermis inflammation and decreased mRNA expression and secretion of IL-33 in MC903-mediated AD mice without interfering with TSLP and IL-1β production. Our results demonstrate a novel ability of NLRP3 to function as a crucial transcription factor of IL-33 in epithelium independently of inflammasome that to mediate the pathological process of AD.

Immune memory has been expanded to group 2 innate lymphoid cells (ILC2s), but the cellular and molecular bases remain incompletely understood. Based on house dust mite (HDM)-induced mice asthma models and human samples, we applied flow cytometry, parabiosis, in vivo imaging and adoptive transplantation to confirm the persistence, migration and function of CD45⁺lineage^–CD90.2⁺NK1.1^–NKp46^–ST2^–KLRG1⁺IL-17RB⁺ memory-like ILC2s (ml-ILC2s). Regulated by CCR9/CCL25 and S1P signaling, ml-ILC2s reside in the lamina propria of small intestines (siLP) in asthma remission, and subsequently move to airway upon re-encountering antigens or alarmins. Furthermore, ml-ILC2s possess properties of longevity, potential of rapid proliferation and producing IL-13, and display transcriptional characteristics with up-regulation of Tox and Tcf-7. ml-ILC2s transplantation restore the asthmatic changes abrogated by Tox and Tcf7 knockdown. Our data identify siLP ml-ILC2s as a memory-like subset, which promotes asthma relapse. Targeting TCF-1 and TOX might be promising for preventing asthma recurrence.

Pudilan antiphlogistic oral liquid (PDL) is a commercial traditional Chinese medicine widely used in the treatment of a variety of inflammatory diseases. However, the specific mechanisms of PDL’s anti-inflammatory effects have not been fully understood. In this research, five classic inflammatory models and a network pharmacology-based strategy were utilized to evaluate its anti-inflammatory efficacy and elucidate its multicomponent and multitarget mode of the anti-inflammatory mechanism. A systems pharmacology approach was carried out via a holistic process of active compound screening, target acquisition, network construction, and further analysis. The potential component–target-associated anti-inflammatory mechanisms of PDL were further verified both in vivo and in vitro. The results showed that PDL exhibited a proven anti-inflammatory effect on multiple types of inflammatory models, including β-hemolytic streptococcus-induced acute pharyngitis, LPS-induced acute lung injury, xylene-induced ear swelling, carrageenan-induced paw edema, and acetic acid-induced capillary permeability-increasing models. Systems pharmacology analysis predicted 45 ingredients of PDL that interact with 185 targets, of which 38 overlapped with the inflammation-related targets. Furthermore, KEGG pathway analysis showed that the predicted targets were mainly involved in hypoxia-inducible factor (HIF)-1, tumor necrosis factor (TNF), nuclear factor kappa-B (NF-κB), and NOD-like receptor (NLR) pathways. Both in vivo and in vitro experiments clarified that PDL has anti-inflammatory potency by inhibiting PI3K and p38 phosphorylation and activating the NLRP3 inflammasome. Our results suggested that PDL has an efficient and extensive anti-inflammatory effect, and its anti-inflammatory mechanisms may involve multiple inflammatory-associated signaling pathways, including HIF-1- and TNF-mediated pathways and NLRP3 inflammasome activation.

Clinically, the treatments against asthma like β2 agonist focus on controlling the symptoms rather than inhibiting recurrence radically. This study aims to evaluate the efficacy and mechanism of a potent Chinese prescription Yu-Ping-Feng-San (YPFS) against asthma recurrence. We here established an optimized house dust mite (HDM)-induced asthma recurrence mice model with typical asthmatic responses such as significantly augmented airway hyperresponsiveness (AHR), elevated serum IgE, pulmonary type 2 cytokines IL-5 and IL-13 levels, pathological changes including thickening bronchial wall, inflammatory infiltration of lung tissue, etc. Moreover, all typical asthmatic pathological features were prominently alleviated by YPFS applied during remission phase ahead of second elicitation, which was even more effective than three different types of medications dexamethasone, montelukast and salbutamol, which were commonly applied in clinical practice, administered during recurrence phase. Besides, we found that desmoglein 1 (DSG1) remained deficient when asthmatic responses regressed whereas tight junction (TJ) claudin 1 (CLDN1) or adherin junction (AJ) E-cadherin restored spontaneously. In vitro, DSG1 interference resulted in increased thymic stromal lymphopoietin (TSLP) secretion, and epithelial barrier compromise evidenced by significantly elevated transepithelial electrical resistance (TEER) and increased 4-kDa FITC-dextran influx. YPFS could downregulate TSLP production and restore HDM-induced DSG1 deficiency and barrier destruction, which was further reversed by shDSG1. Collectively, administration of YPFS in remission prominently alleviated HDM-induced asthma relapse by restoring DSG1 and decreasing TSLP overexpression, which might be the key factors contributing to chronic asthma relapse. Our data not only demonstrated the pivotal role of DSG1 in asthma pathogenesis, but also provided a novel and potent therapeutic strategy against chronic asthma.