Use of lipoplex-induced nuclear factor-kappa B activation to enhance transgene expression by lipoplex in mouse tung

Background Although lipofection-induced TNF-alpha. can activate nuclear factor kappa B (NF-kappa B), which, in turn, increases the transgene expression from plasmid DNA in which any NF-kappa B responsive element is incorporated, no attempts have been made to use such biological responses as NF-kappa B activation against a vector to enhance vector-mediated gene transfer. Methods A lipoplex composed of N-[1-(2,3-dioleyloxy)propyl]-N,N,N-trimethylammonium and cholesterol liposome and plasmid DNA encoding firefly luciferase under the control of the cytomegalovirus immediate early promoter (pCMV-Luc) was intravenously injected into mice. Luciferase activity as well as NF-KB activation in the lung were evaluated. Then, a novel plasmid DNA, PCMV-kappa B-Luc, was constructed by inserting 5 repeats of NF-kappa B-binding sequences into the pCMV-Luc. Results NF-kappa B in the lung was activated by injection of the lipoplex and its nuclear localization was observed. An injection of lipopolysaccharide 30 min prior to the lipofection further activated NF-kappa B. At the same time, the treatment significantly increased the transgene expression by lipoplex, suggesting a positive correlation between expression and NF-kappa B activity. Based on these findings, we tried to enhance the lipoplex-based transgene expression by using NF-kappa B activation. The lipoplex consisting of pCMV-kappa B-Luc showed a 4.7-fold increase in transgene expression in the lung compared with that with pCMV-Luc. Conclusions We demonstrated that NF-kappa B activation by lipoplex can be used to enhance lipoplex-mediated transgene expression by inserting NF-kappa B-binding sequences into plasmid DNA. These findings offer a novel method for designing a vector for gene transfer in conjunction with biological responses to it. Copyright (c) 2005 John Wiley & Sons, Ltd.