Zinc finger and broad-complex, tramtrack, and bric-a-brac domain containing 16 silencing attenuates bleomycin-induced pulmonary fibrosis in mice through inhibition of the phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin pathway.

Objective: Idiopathic pulmonary fibrosis (PF) is a chronic and life-threatening lung disease. This study aimed to investigate the role of zinc finger and BTB domain containing 16 (Zbtb16), a transcription factor, in the progression of PF by analyzing its expression and regulatory effects in mouse and cell models.

Material and methods: The gene expression profiles in bleomycin-induced (BL-I) PF lung tissues of mice were analyzed using the gene expression omnibus database. The mouse model of BL-I PF and cell model of transforming growth factor-β1 (TGF-β1)-induced mice lung epithelial cell (LEC) fibrosis was constructed. Zbtb16 expression was evaluated by reverse transcription quantitative polymerase chain reaction, Western blot, or immunohistochemistry. Tissue sections were assessed by hematoxylin and eosin, Masson, and terminal deoxynucleotidyl transferase dUTP nick-end labeling staining. The levels of protein, inflammation factors, and albumin were measured through Western blot or enzyme-linked immunosorbent assay.

Results: Bioinformatics analysis found that Zbtb16 was the highest differentially expressed marker in BL-I PF mice. Zbtb16 was highly expressed in the mice and cell model. Zbtb16 silencing could reduce lung tissues' collagen deposition, pulmonary edema, and pulmonary apoptotic cells; improve vascular permeability; and decrease fibrosis markers and inflammation factors expressed in model mice. Zbtb16 silencing could reduce fibrosis markers and inflammation factor levels in the cell model (P < 0.05). Kyoto encyclopedia of genes and genomes and gene set enrichment analyses suggested that Zbtb16 might regulate BL-I PF in mice through the phosphoinositide 3-kinases (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathway (PAmT-P). Co-immunoprecipitation showed the combination of AKT and Zbtb16. PAmT-P in the mice model and cell model was visibly activated (P < 0.05), and Zbtb16 silencing could inhibit it (P < 0.05). Moreover, the rescue experiments showed that the AKT activator SC79 could reverse the effect of TGF-β1 + small interfere RNA-Zbtb16 on LECs.

Conclusion: This study identified Zbtb16 as a key regulator of PF progression, mediating its effects through the PAmT-P. Zbtb16 silencing alleviated fibrosis and inflammation in vivo and in vitro, providing a promising target for therapeutic intervention in PF.