Phycocyanin From Spirulina Platensis Attenuates Pulmonary Fibrosis Through TLR2-MyD88-NF-κB Signalling Pathway

Object:In this paper,pulmonary fibrosis mice model were used to study the protective effect of PC on pulmonary fibrosis,and provide theoretical basis for clinical research.Methods:50 C57 BL/6 male,6-8 weeks mice were used for pre experiment.To explore the optimal therapeutic dose of PC to protect the pulmonary fibrosis,the pulmonary fibrosis mice model was established by intratracheal injection of BLM 5 mg/kg.In addition,120 wide type and 120 TLR2-/-mice were obtained to conduct a formal experiment.Every type of mice was divided into control group,PC group,BLM group and BLM+PC group.Serum and lung tissue were collected after BLM treatment 3 days,7 days and 28 day respectively.Then lung wet dry ratio,MPO,HE stain with pathological inflammation score(or fibrosis score),IL-6,TNF-a,HYP content,MDA level and SOD activity were measured.Changes of epithelial cells and stromal cells were detected by immunofluorescence.Besides,the transcription and translation of TLRs signaling pathway related molecules in lung tissue were detected by western blot and RT-PCR.Results:1.In pre-experiment,HE and Masson stain suggested that the protective effect of PC(50mg/kg)is better than medium(100mg/kg)and high dosage(200mg/kg).2.Compared with Control group,HE stain、lung W/D ratio and MPO activity had no significant changes in BLM group at 3day.However,IL-6,TNF-a and TLR2-MyD88-NF-κB signaling pathway were obviously increased in BLM group.PC treatment significantly decreased these expressions.TLR2 deficiency these protects of PC.3.Compared with Control group,IL-6,TNF-α,W/D ratio,MPO and TLR2-MyD88-NF-KB signaling pathway were significantly increased in BLM group.Except these,HE stain showed obvious disturbances in the alveolar space,alveolar septum-widened,fusion of pulmonary alveoli and inflammatory cell infiltrate.PC treatment made a downregulation in these expressions.TLR2 deficiency these protects of PC.4.Data showed that PC treatment dramatically decreased the levels of HYP,PDPN,SP-C,S100A4,a-SMA,vimentin and MDA,and significantly increased the expression of E-cadherin,SOD activity on 28-day post-BLM treatment.TLR2 deficiency these protects of PC.Conclusion:the present study demonstrates that the anti-fibrotic effects of PC may be mediated by alleviating IL-6 and TNF-α release,protecting type Ⅰ alveolar epithelial cells,inhibiting fibroblast proliferation,attenuating epithelial-mesenchymal transitions(EMT).The TLR2-MyD88-NF-KB signaling pathway plays an important role in above processes.