Effect of intragastric administration of cannabidiol in improving bleomycin-induced pulmonary fibrosis mice and the mechanism

ZHANG Feiyu; SUN Mengdi; YANG Huicong; LU Fang; YU Donghua; LIU Shumin

doi:10.3969/j.issn.1002-266X.2023.33.003

Abstract：Objective To investigate the effect of intragastric administration of cannabidiol(CBD)in improving bleomycin-induced pulmonary fibrosis mice and to explore its mechanism of action.Methods On the first day of the ex-periment,60 Balb/c mice were randomly divided into the control group,model group,prednisone group,low-dose CBD group,medium-dose CBD group,and high-dose CBD group,with 10 mice in each group.The pulmonary fibrosis models were established through intraperitoneal injection of bleomycin for 4 consecutive weeks for all groups except the control group;and the mice in the control group received intraperitoneal injection of an equal volume of normal saline.On the 29th day of the experiment,mice in the prednisone group,low-dose CBD group,medium-dose CBD group,and high-dose CBD group were given prednisone(12 mg/kg)and CBD(12 mg/kg,36 mg/kg,and 108 mg/kg)by gavage,respective-ly,once a day,for 28 consecutive days;mice in the model group and control group received the same volume of normal sa-line.On the 56th day of the experiment,the mice were euthanized under anesthesia to collect the lung tissues.The lung tissues were examined for pathological changes with HE staining and Masson staining;the severity of pulmonary alveolitis and fibrosis was scored;the level of hydroxyproline(HYP)was detected by the micromethod;and the relative mRNA ex-pression levels of nuclear factor-kappa B(NF-κB)p65,nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3),apoptosis-associated speck-like protein containing a C-terminal caspase recruitment domain(ASC),caspase-1,and gasdermin D were deteted by real-time PCR.Serum levels of Krebs Von den Lungen-6(KL-6),matrix metalloprotein-ase-7(MMP-7),interleukin-1β(IL-1β),and interleukin-18(IL-18)were measured using ELISA.Results The lung tissue and alveolar structure of the mice in the control group were intact and clear;the model group developed alveolitis,with a large number of inflammatory cells(monocytes,neutrophils,plasma cells,lymphocytes,etc.)infiltrating the alveo-lar wall and lung interstitium;and the prednisone group and the three CBD groups showed basically normal alveolar struc-ture,with varying degrees of reductions in inflammatory cell infiltration.Compared with the control group,the severity scores of alveolitis and pulmonary fibrosis in the model group significantly increased(all P<0.05);the severity scores of alveolitis and pulmonary fibrosis significantly decreased in the prednisone group and the low-dose,medium-dose,and high-dose CBD groups in comparison with those of the model group(all P<0.05),and there was a dose-dependent relationship among the CBD groups(P<0.05).Compared with the control group,the HYP level in the lung tissues and serum KL-6 and MMP-7 levels significantly increased in the model group(all P<0.05);compared with the model group,the HYP lev-el in the lung tissues and serum KL-6 and MMP-7 levels decreased in the low-dose,medium-dose,high-dose CBD groups as well as the prednisone group(all P<0.05),and there was a dose-dependent relationship among the CBD groups(all P<0.05).The relative expression levels of NF-κB p65,NLRP3,ASC,Caspase-1,and Gasdermin D mRNA in the lung tis-sues and the levels of IL-1β and IL-18 in serum were higher in the model group than in the control group(all P<0.05),which were lower in the prednisone group and the low-dose,medium-dose,high-dose CBD groups than in the model group(all P<0.05),and there was a dose-dependent relationship among the CBD groups(P<0.05).Conclusion The intra-gastric administration of CBD can improve bleomycin-induced pulmonary fibrosis mice,and the mechanism of action may be related to inhibiting the NF-κB signaling pathway,reducing the expression of NLRP3 inflammasome-related protein,and inhibiting the classical pyroptosis pathway.