H&E examination and immunohistochemistry assay
The tissues fixed in 4% formaldehyde were embedded in paraffin after dehydration in a gradient ethanol series (70–100%). Cut embedded sections (4 μm thick) with a rotary microtome and subjected to hematoxylin and eosin (H&E) staining, Masson staining, periodic acid-Schiff (PAS) staining, and Sirius red staining, or labeled with TGF-β1 (BD Biosciences Cat# 562423, RRID: AB_2737615, Guangzhou, China) for microscopic examination. Sections were viewed with a light microscope (Olympus, Japan) and photographed at ×100 magnification. The sections of histological examination and immunohistochemistry image were firstly labeled by an identification number code without the information of the grouping. The numbers of TGF-β1 labelled cells in each slide were counted by using the Image J software (Macbiophotonics, Hamilton, Canada). Quantification analysis was performed in six randomly selected fields per sample in a blinded manner.