Huaxun Wu1, Jingyu Chen1, Chun Wang1, Lihua Liu1, Yujing Wu1, Yunfang Zhang1, Aiwu Zhou1, Lingling Zhang1, Wei Wei2. 1. Institute of Clinical Pharmacology of Anhui Medical University, Key Laboratory of Anti-Inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-Inflammatory and Immune Medicine, Hefei, 230032, China. 2. Institute of Clinical Pharmacology of Anhui Medical University, Key Laboratory of Anti-Inflammatory and Immune Medicine, Ministry of Education, Anhui Collaborative Innovation Center of Anti-Inflammatory and Immune Medicine, Hefei, 230032, China. wwei@ahmu.edu.cn.
Abstract
OBJECTIVE: To investigate the effects of β-AR signaling on fibroblast-like synoviocytes (FLS) from adjuvant-induced arthritis (AA) rats and the partial mechanisms focused on β-AR desensitization mediated by GRK2 and β-arrestin2. METHODS: Animals were divided into a control group and an AA model group, and FLSs were cultured. Arthritis index, histopathology of joints, epinephrine (Epi) and norepinephrine (NE) were detected in vivo. The effect of the β-AR agonist isoprenaline (ISO) and the β2-AR agonist salbutamol on FLS cell viability were detected by CCK8. Cytokines TNF-α, IL-1β, OPG and RANKL were examined by ELISA. The expression of β2-AR was detected by immunofluorescence and flow cytometry. The cytomembrane expression and desensitization of β2-AR, GRK2, and β-arrestin2 were measured by flow cytometry and western blot. RESULTS: The concentration of NE increased to a peak on day 21, which was consistent with the arthritis index. The levels of Epi and NE in synovial tissues were decreased. ISO inhibited FLS cell viability and TNF-α, IL-1β, and RANKL secretion, and promoted OPG secretion. β2-AR mediated the effects of ISO on FLS cell viability. β2-AR signaling was weaker in AA rats compared to the controls. Elevated GRK2 and β-arrestin2 in cytomembranes promoted β2-AR desensitization and may decrease the anti-inflammatory effect of β2-AR signaling. CONCLUSION: The activation of β2-AR signaling exerts its anti-inflammatory activities on FLS. β2-AR signaling decreased in the AA model, which might be related to the increased membrane expression of GRK2 and β-arrestin2, and promoted the excessive desensitization of β2-AR. Decreased β2-AR signaling may be relevant to the exacerbation of arthritis inflammation.
OBJECTIVE: To investigate the effects of β-AR signaling on fibroblast-like synoviocytes (FLS) from adjuvant-induced arthritis (AA) rats and the partial mechanisms focused on β-AR desensitization mediated by GRK2 and β-arrestin2. METHODS: Animals were divided into a control group and an AA model group, and FLSs were cultured. Arthritis index, histopathology of joints, epinephrine (Epi) and norepinephrine (NE) were detected in vivo. The effect of the β-AR agonist isoprenaline (ISO) and the β2-AR agonist salbutamol on FLS cell viability were detected by CCK8. Cytokines TNF-α, IL-1β, OPG and RANKL were examined by ELISA. The expression of β2-AR was detected by immunofluorescence and flow cytometry. The cytomembrane expression and desensitization of β2-AR, GRK2, and β-arrestin2 were measured by flow cytometry and western blot. RESULTS: The concentration of NE increased to a peak on day 21, which was consistent with the arthritis index. The levels of Epi and NE in synovial tissues were decreased. ISO inhibited FLS cell viability and TNF-α, IL-1β, and RANKL secretion, and promoted OPG secretion. β2-AR mediated the effects of ISO on FLS cell viability. β2-AR signaling was weaker in AA rats compared to the controls. Elevated GRK2 and β-arrestin2 in cytomembranes promoted β2-AR desensitization and may decrease the anti-inflammatory effect of β2-AR signaling. CONCLUSION: The activation of β2-AR signaling exerts its anti-inflammatory activities on FLS. β2-AR signaling decreased in the AA model, which might be related to the increased membrane expression of GRK2 and β-arrestin2, and promoted the excessive desensitization of β2-AR. Decreased β2-AR signaling may be relevant to the exacerbation of arthritis inflammation.