Fibulin-5 promotes fibroblast activation through LTBP-4 to improve the pathogenesis of hemorrhoids.

BACKGROUND: Hemorrhoid disease is a widespread gastrointestinal ailment caused by the degeneration of supporting tissues within the anal cushions. Despite its high incidence, the pathogenic processes involved remain poorly elucidated. OBJECTIVE: This study sought to clarify the functions of Fibulin-5 (FBLN5) and latent transforming growth factor beta binding protein 4 (LTBP-4) in activating fibroblasts and their combined impact on hemorrhoid pathogenesis, while exploring their potential as therapeutic targets. METHODS: A rat model of hemorrhoid was created by injecting glacial acetic acid into the region surrounding the anus. Fibroblast migration was assessed using a scratch test, while cell viability was assessed with CCK-8. Protein and gene expression levels of FBLN5, LTBP-4, COL1A2, Elastin, and fibronectin were measured by Western blotting and RT-PCR. Immunofluorescence and immunohistochemistry were employed to localize and visualize protein localization and expression. Plasmid transfection experiments assessed the effects of FBLN5 and LTBP-4 overexpression or knockdown on fibroblast behavior. RESULTS: Hemorrhoidal tissues in the experimental group exhibited significant structural alterations, with notable reductions in the expression of FBLN5, LTBP-4, α-SMA, COL1A2, Elastin, and Fibronectin compared to controls. Primary fibroblasts derived from hemorrhoid tissues exhibited reduced migratory ability and downregulated key fibrotic markers. Overexpression of FBLN5 or LTBP-4 restored fibroblasts' viability and migration, while LTBP-4 knockdown attenuated the beneficial effects of FBLN5, highlighting their synergistic role in extracellular matrix remodeling. CONCLUSION: FBLN5 and LTBP-4 play significant roles in activating fibroblasts and contributing to the pathogenesis of hemorrhoid disease. Targeting these proteins could provide novel therapeutic approaches to enhance the outcomes of hemorrhoid treatment.