Abstract
Ethnopharmacological relevance
The HuaTanJiangQi formula (HTJQ), a compound preparation composed of multiple traditional Chinese herbs, has been classically used to treat respiratory diseases caused by inflammation. Furthermore, it has been demonstrated to alleviate inflammatory damage in glucocorticoid (GC)-resistant chronic obstructive pulmonary disease (COPD). However, the mechanism by which it regulates Nrf2 signaling pathways to alleviate GC resistance remains unclear.Aim of the study
This study investigated whether HTJQ ameliorates GC resistance in COPD by regulating the CYP2J2/EETs/NF-κB molecular axis via Nrf2.Materials and methods
Cigarette smoke (CS) and lipopolysaccharide (LPS)-induced GC-resistant COPD rats were used to investigate the anti-inflammatory and regulatory effects of HTJQ on CYP2J2/EETs/NF-κB and Nrf2. Enzyme-linked immunosorbent assay (ELISA), immunohistochemistry (IHC), hematoxylin and eosin (H&E) staining, and Western blotting (WB) were conducted to assess resistance status and the expression characteristics of molecular targets in model rats treated with HTJQ. Cigarette smoke extract (CSE) and LPS-induced GC-resistant HBE135-E6E7 cells were used to investigate the interaction of the CYP2J2/EETs/NF-κB axis and the regulatory effects of HTJQ through activating Nrf2. Western blotting (WB) was used to evaluate the expression of CYP2J2/EETs/NF-κB axis members, and the expression of downstream transcription factors was quantified via qPCR. The regulatory interaction of axis members was evaluated through intervention with 14,15-epoxyeicosatrienoic acid (14,15-EET), CYP2J2 siRNA and inhibitor, and Nrf2 siRNA and inhibitor.Key results
HTJQ markedly suppressed NF-κB activation and reduced IL-8 and TNF-α levels in CSE- and LPS-stimulated HBE135-E6E7 cells, alleviating GC resistance. Furthermore, HTJQ ameliorated the symptoms of GC-resistant COPD in rats, such as airway inflammation, pulmonary function decline (FEV0.3/FVC, PEF), alveolar destruction, histopathological injury, and elevated inflammatory cytokine levels in BALF and serum. Moreover, HTJQ upregulated CYP2J2 expression and 14,15-EET levels while inhibiting NF-κB activation in lung tissues and airway epithelial cells. Mechanistically, HTJQ activated Nrf2 to promote CYP2J2 transcription, thereby increasing 14,15-EET synthesis and the subsequent inhibition of NF-κB, forming a regulatory axis that restores glucocorticoid sensitivity.Conclusions and implications
HTJQ can alleviate the inflammatory response, ameliorate lung tissue damage, and regulate endogenous metabolism by activating Nrf2 in a GC-resistant COPD model. This anti-resistance effect was achieved through the CYP2J2/EETs/NF-κB molecular axis.