Psoralen attenuates cigarette smoke extract-induced inflammation by modulating CD8+T lymphocyte recruitment and chemokines via the JAK2/STAT1 signaling pathway

Chronic obstructive pulmonary disease (COPD) is a respiratory inflammatory disease. Psoralen (PSO) is the main pharmacological component identified from Bu-Shen-Fang-Chuan formula which has been traditionally used in treatment of COPD, yet its efficacy in COPD inflammation were unreported. In this study, we aimed to elucidate the anti-inflammatory potential of PSO in COPD and unravel the underlying mechanisms, focusing on T lymphocyte recruitment and the modulation of chemokines, namely monokine induced by interferon-gamma (CXCL9), interferon inducible protein 10 (CXCL10), and interferon inducible T-Cell alpha chemoattractant (CXCL11). In vitro, RAW264.7 was stimulated by interferon (IFN)-gamma + cigarette smoke extract (CSE) and were treated with PSO (2.5, 5, 10 mu M), then the levels of chemokines and the activation of Janus kinase (JAK)/Signal transducer and activator of transcription 1 (STAT1) pathway were analyzed by real time PCR and western blot. In vivo, a murine model was established by intraperitoneal injection of CSE on day 1, 8, 15, and 22, then treated with PSO (10 mg/kg). Our experiments in vitro illustrated that PSO reduced the levels of CXCL9, CXCL10, and CXCL11, and decreased the protein phosphorylation levels of JAK2 and STAT1. Additionally, PSO effectively improved inflammatory infiltration and decreased the proportion of CD8+ T cells in CSE-exposed mice. Furthermore, PSO reduced the levels of CXCL9, CXCL10, and CXCL11 in bronchoalveolar lavage fluid (BALF) and lung tissue, and decreased the protein phosphorylation levels of JAK2 and STAT1. In conclusion, our results revealed the therapeutic potential of PSO for COPD inflammation, possibly mediated through the regulation of CD8+ T cell recruitment and chemokines via the JAK2/STAT1 signaling pathway.