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 β1-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 β1 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 μΜ. Human gingival fibroblasts (HFG) were grown for 24 hours in each concentration and fluorescein-labeled with a mouse monoclonal anti-human β1 antibody and secondarily incubated with a urease-labeled anti-mouse lgG antibody. After a final wash, the cells were incubated with urea/bromcresol blue substrate for 15 minutes at 37°C and measured in a microplate reader at 570 nm. Results: The integrin β1-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 μΜ versus controls (P<0.05). Conclusions: Nicotine concentrations of 0.2 and 0.4 μΜ significantly decrease β1 integrin expression in human gingival fibroblasts that may affect cell-cell and cell-substratum adhesion during wound healing.