Effect of nicotine on fibroblast β1 integrin expression and distribution in vitro

Background: Integrins are a family of transmembrane cell surface glycoproteins, and those with the beta (1)-subunit function in both cell-to-cell and cell-to-substrate adhesion. The purpose of this study was to determine nicotine's effect on the expression and distribution of the beta (1) integrin subunit on the human gingival fibroblast cell surface. Methods: Pure nicotine was diluted in medium to the following concentrations: 0 (control), 0.025, 0.05, 0.1, 0.2, and 0.4 muM. Human gingival fibroblasts (HFG) were grown for 24 hours in each concentration and fluorescein-labeled with a mouse monoclonal anti-human beta (1) antibody and secondarily incubated with a urease-labeled anti-mouse IgG antibody. After a final wash, the cells were incubated with urea/bromcresol blue substrate for 15 minutes at 37 degreesC and measured in a microplate reader at 570 nm. Results: The integrin beta (1)-subunit was detected on the HGF surface membrane by fluorescence labeling, and cell-enzyme-linked immunosorbent assay testing demonstrated its decreased expression with increasing nicotine concentrations that were statistically different at the concentrations of 0.2 and 0.4 muM versus controls (P <0.05). Conclusions: Nicotine concentrations of 0.2 and 0.4 <mu>M significantly decrease beta (1) integrin expression in human gingival fibroblasts that may affect cell-cell and cell-substratum adhesion during wound healing.