Galectin‐8 mediates fibrogenesis induced by cyclosporine in human gingival fibroblasts

Background and Objective During cyclosporine‐induced gingival overgrowth, the homeostatic balance of gingival connective tissue is disrupted leading to fibrosis. Galectins are glycan‐binding proteins that can modulate a variety of cellular processes including fibrosis in several organs. Here, we study the role of galectin‐8 (Gal‐8) in the response of gingival connective tissue cells to cyclosporine. Methods We used human gingival fibroblasts and mouse NIH3T3 cells treated with recombinant Gal‐8 and/or cyclosporine for analyzing specific mRNA and protein levels through immunoblot, real‐time polymerase chain reaction, ELISA and immunofluorescence, pull‐down with Gal‐8‐Sepharose for Gal‐8‐to‐cell surface glycoprotein interactions, short hairpin RNA for Gal‐8 silencing and Student's t test and ANOVA for statistical analysis. Results Galectin‐8 stimulated type I collagen and fibronectin protein levels and potentiated CTGF protein levels in TGF‐β1‐stimulated human gingival fibroblasts. Gal‐8 interacted with α5β1‐integrin and type II TGF‐β receptor. Gal‐8 stimulated fibronectin protein and mRNA levels, and this response was dependent on FAK activity but not Smad2/3 signaling. Cyclosporine and tumor necrosis factor alpha (TNF‐α) increased Gal‐8 protein levels. Finally, silencing of galectin‐8 in NIH3T3 cells abolished cyclosporine‐induced fibronectin protein levels. Conclusion Taken together, these results reveal for the first time Gal‐8 as a fibrogenic stimulus exerted through β1‐integrin/FAK pathways in human gingival fibroblasts, which can be triggered by cyclosporine. Further studies should explore the involvement of Gal‐8 in human gingival tissues and its role in drug‐induced gingival overgrowth.