Hematoxylin and eosin staining, Masson's trichrome staining and Sirius Red staining

Tissue staining was performed as previously described⁵. Pancreatic tissues were immediately fixed in 4% paraformaldehyde for paraffin embedding. Tissue specimens were cut into 4-μm thick serial sections for hematoxylin and eosin (H&E) staining, Masson's trichrome staining and Sirius Red staining. H&E staining was performed using a commercial kit (Catalog No. C0105, Beyotime) according to the manufacturer's instructions. Masson's trichrome staining was performed with a staining kit following the manufacturer's protocol (Catalog No. G1340, Solarbio). Sirius Red staining of paraffin-embedded pancreas sections was performed with a staining kit (Catalog No. S8060, Solarbio). Fibrotic areas that appeared blue under Masson's trichrome staining and Red under Sirius Red staining were quantified by ImageJ 1.43 (W. S. Rasband, ImageJ, National Institutes of Health). The non-pancreatic regions were subtracted when calculating the total area of pancreatic tissue in the selected field. The percentage of the fibrotic area was calculated from the ratio of fibrotic tissue to total pancreatic tissue.