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

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.

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.

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.

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.

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.