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

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

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.

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).

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.