Therapeutic effect of phycocyanin on chronic obstructive pulmonary disease in mice.

INTRODUCTION: The prevention and treatment of chronic obstructive pulmonary disease (COPD) is closely tied to anti-oxidation and anti-inflammation. Phycocyanin (PC) have numerous pharmacological effects such as anti-oxidation, anti-inflammation, and so on. But it remains unclear whether PC can play a therapeutic role in COPD.

OBJECTIVE: As inflammation and oxidative stress can aggravate the COPD, this study is to explore the effect of PC on COPD mice and its mechanisms.

METHODS: COPD mice model was established by exposing to lipopolysaccharide (LPS) and cigarette smoke (CS), PC was administrated in the concentration of 50 mg/kg for 30 days. On the last day, lung function was measured, and bronchoalveolar lavage fluid (BALF) was obtained and classified for cell. Lung tissues pathological change was analyzed and organ indices statistics were measured. Based on molecular docking the mechanism was explored with Western blotting, immunohistochemical and immunofluorescence in vivo and in vitro.

RESULTS: PC significantly ameliorated the pulmonary function of COPD mice and reduced inflammation of lung (p<0.05), Hematoxylin eosin (H&E) showed PC depressed lung inflammatory cell accumulation and emphysema. Periodic acid Schiff (PAS) and Masson staining revealed that PC retarded goblet cells metaplasia and collagen deposition (p<0.05). In addition, in vivo PC regulated Heme oxygenase 1 (HO-1) (p<0.05) and NAD(P)H dehydrogenase quinone 1 (NQO1) level (p<0.01) in lung, as well as NOX2 level in pulmonary macrophages. Molecular docking results indicate that phycocyanobilin (PCB) in PC had a good binding site in Keap1 and NOX2 proteins, The phycocyanobilin-bound phycocyanin peptide (PCB-PC-peptide) were obtained for further studies. in vitro PCB-PC-peptide could depress the phospho-NF-E2-related factor 2 (p-Nrf2) and NQO1 protein expression in RAW264.7 cells induced by cigarette smoke extract (CSE) (p<0.05).

CONCLUSION: PC exerts beneficial effects in COPD via anti-inflammatory and anti-oxidative stress, which may be achieved through PCB.