Dahuang Zhechong Pill Improves Pulmonary Fibrosis through miR-29b-2-5p/HK2 Mediated Glycolysis Pathway.

Objective: To explore the preventive and therapeutic effects of Dahuang Zhechong Pill (DZP) on pulmonary fibrosis and the underlying mechanisms.

Methods: The first key rate-limiting enzyme hexokinase 2 (HK2) of glycolysis was silenced and over-expressed through small interfering RNA and lentivirus using lung fibroblast MRC-5 cell line, respectively. The cell viability, migration, invasion and proliferation were detected by cell counting kit-8, wound healing assay, transwell assay, and flow cytometry. The mRNA and protein expression levels of HK2 were detected by RT-PCR and Western blotting, respectively. The contents of glucose, adenosine triphosphate (ATP) and lactate in MRC-5 cells were determined by enzyme-linked immunosorbnent assay (ELISA). Then, the relationship between miR-29b-2-5p and HK2 was explored by luciferase reporter gene assay. Pulmonary fibrosis cell model was induced by transforming growth factor-β 1 (TGF-β 1) in MRC-5 cells, and the medicated serum of DZP (DMS) was prepared in rats. MRC-5 cells were divided into control, TGF-β 1, TGF-β 1+10% DMS, TGF-β 1+10% DMS+miR-29b-2-5p inhibitor, TGF-β 1+10% DMS+inhibitor negative control, TGF-β 1+10% DMS+miR-29b-2-5p mimic and TGF-β 1+10% DMS+mimic negative control groups. After miR-29b-2-5p mimics and inhibitors were transfected into MRC-5 cells, all groups except control and model group were treated with DMS. The effect of DMS on MRC-5 cells were detected using aforementioned methods and immunofluorescence. Similarly, the contents of glucose, ATP and lactate in each group were measured by ELISA.

Results: The mRNA and protein expressions of HK2 in MRC-5 cells were successfully silenced and overexpressed through si-HK2-3 and lentiviral transfection, respectively. After silencing HK2, the mRNA and protein expressions of HK2 were significantly decreased (P<0.01), and the concentrations of glucose, ATP and lactate were also significantly decreased (P<0.05). The proliferation, migration and invasion of MRC-5 cells were significantly declined (P<0.05 or P<0.01), while the apoptosis of MRC-5 cells was significantly increased (P<0.01). After overexpressing HK2, the mRNA and protein expressions of HK2 were significantly increased (P<0.05), and the concentrations of glucose, ATP and lactate were also significantly increased (P<0.05 or P<0.01). The proliferation, migration and invasion of MRC-5 cells were significantly increased (P<0.05 or P<0.01), while the apoptosis of MRC-5 cells was significantly decreased (P<0.05). The relative luciferase activity of 3'UTR-WT+hsa-miR-29b-2-5p transfected with HK2 was significantly decreased (P<0.01). After miR-29b-2-5p mimic and inhibitor were transfected into the MRC-5 cells, DMS intervention could significantly reduce the concentration of glucose, ATP and lactate, and the mRNA and proteins expressions of HK2, phosphofructokinase and pyruvate kinase isoform M2 (P<0.05 or P<0.01). The proliferation, migration and invasion of MRC-5 cells were alleviated (P<0.05 or P<0.01), and the deposition of fibronectin, α-smooth muscle actin, and collagen I were significantly decreased (P<0.05 or P<0.01).

Conclusions: Glycolysis is closely related to pulmonary fibrosis. DZP reduced glycolysis and inhibited fibroblasts' excessive differentiation and abnormal collagen deposition through the miR-29b-2-5p/HK2 pathway, which played a role in delaying the process of pulmonary fibrosis.