Xiao Qing Long Tang ameliorates neutrophil extracellular trap-dendritic cells-T helper 17 cell axis in Neutrophilic Asthma

by Xiaoying Ji, Hongda Chen, Sheng-dong He, Min Huang, Xiaoli You, Chuan Xiao, Zhifeng Chen, Jinwen Cai

Neutrophilic asthma (NA) is an allergic airway inflammation disease featuring heterogeneous neutrophil infiltration, which is driven by the interactions between dendritic cells (DCs) and T helper (Th) 17 cells. Neutrophils release neutrophil extracellular traps (Nets), which promote disease progression and glucocorticoid resistance. Therefore, targeting the interaction among Nets, DC and Th17 is a promising pathway for preventing organ damage. Traditional Chinese Medicine (TCM), especially Xiao-qing-long-tang (XQLT), has shown potential in managing eosinophilic asthma by modulating Th2 cell-mediated inflammation, reducing eosinophilic infiltration, and airway remodeling. However, XQLT’s effect on Nets and DCs-Th17 interactions in NA remains unclear.

We developed two models: an ovalbumin (OVA)/lipopolysaccharide (LPS)-induced NA mouse model with interventions using either XQLT or sivelestat, and a series of bone marrow-derived dendritic cells (BMDCs)-Th17 cell differentiation models induced by Nets, OVA/LPS, OVA/LPS/Nets, XQLT, OVA/LPS/Nets/XQLT, or corresponding inhibitors. The chemical composition of XQLT was analyzed using ultra-performance liquid chromatography-mass spectrometry (UPLC-MS). Key parameters were evaluated via histopathology, immunohistochemistry, immunofluorescence scanning, flow cytometry, Western blot (WB) analysis, and enzyme-linked immunosorbent assay (ELISA).

In OVA/LPS-induced mice, treatment with sivelestat in OVA/LPS-induced mice reduced airway inflammation, Nets formation characterized by citrullinated histone H3 (CitH3) and myeloperoxidase (MPO) expressions, Th2/17 cell proportions in lungs, and interleukin (IL)-4, 6, 17, and 23 levels in bronchoalveolar lavage fluid (BALF). In vitro, OVA/LPS/Nets promoted IL-6/23 secretions and Th17 differentiation through increased p38 mitogen-activated protein kinase (MAPK)/nuclear factor κB (NF-κB) signaling phosphorylation in DCs. Fifty-one compounds were identified in XQLT, with 11 predicted to bind MAPK proteins with high affinity. XQLT significantly inhibited Nets-DCs-Th17 Axis and p38MAPK/NF-κB signaling in both NA mouse and cell models.

XQLT offered a promising treatment strategy for regulating the Nets-DCs-Th17 axis in NA.