Gene transfer to the respiratory tract by replication-deficient adenoviruses is limited by the induction of inflammatory and immune responses. We previously demonstrated that a E1-E3-deleted recombinant adenovirus carrying the expression cassette for the cystic fibrosis gene (Ad.CFTR) upregulates the expression of the pro-inflammatory intercellular adhesion molecule-1 (ICAM-1) both in vitro and in vivo. In the present work we suggest a role for the nuclear factor-kB (NF-kB) in Ad.CFTR-dependent up-regulation of ICAM-1 in respiratory epithelial A549 cells. Specifically, Ad.CFTR induced translocation of NF-kB into the nucleus and binding to the proximal −228/−218 NF-kB consensus sequence on the ICAM-1 pro-

Replication-defective adenoviruses (Ad) utilized as vectors for gene transfer are known to induce an inflammatory and immune response upon exposure to respiratory cells in vitro and in vivo. Among the different mediators of inflammation, we recently demonstrated that a replication-defective Ad serotype 5, deleted in the early genes E1 and E3 (Ad.CFTR), induces the proinflammatory intercellular adhesion molecule 1 (ICAM-1) in A549 respiratory cells in vitro and in lung portions of nonhuman primates in vivo, Gene Ther. 5, 131-136). More recently, we described the involvement of the nuclear factor kappaB (NF-kappaB) in the induction of ICAM-1 upon 24 h of exposure of the same Ad5-derived vector, Gene Ther. 8, 1436-1442). Here we investigated whether the early phase of virus-cell interaction is sufficient to stimulate ICAM-1 upregulation. A549 cells were exposed to wild-type Ad5 (Ad5), to Ad.CFTR, and to Ad5 inactivated by incubation at 56 degrees C (Ad5/56 degrees C). Ad5, Ad.CFTR, and Ad5/56 degrees C activated NF-kappaB and increased ICAM-1 mRNA levels within 4 h after exposure. The role of the mitogen-activated protein kinases (MAPKs) on the ICAM-1 mRNA induction was studied. ICAM-1 mRNA upregulation was inhibited upon incubation with several chemicals, namely, the ERK1/2 inhibitors PD98059 and AG1288 (by 98 and 67%, respectively), of the p38/MAPK pathway SB203580 (by 50%), of the JNK pathway dimethylaminopurine (by 83%), and of the NF-kappaB parthenolide (by 96%). Ad5 and Ad5/56 degrees C stimulated ERK1/2, p38/MAPK, and JNK1 starting 10 min and peaking 20-30 min after exposure. The present results indicate a link between the activation of the three major MAPK pathways, NF-kappaB, and the upregulation of ICAM-1 gene expression evoked by Ad5 in the very initial phase of infection.

Cystic fibrosis is caused by defects in a chloride-transporting protein termed cystic fibrosis transmembrane conductance regulator (CFTR). This study presents an innovative procedure to evaluate expression of functional CFTR. The technique uses the potential-sensitive probe bis-(1,3-diethylthiobarbituric acid) trimethine oxonol or DiSBAC2(3), by single-cell fluorescence imaging. The DiSBAC2(3) method was first validated on the mouse mammary tumor cell line C127, stably expressing wild-type CFTR. Activation of protein kinase A by the cAMP-permeable analogue 8-Br-cAMP induced cell membrane depolarization consistent with expression of wild-type CFTR. The DiSBAC2(3) method is quick, simple, and reproducible, and does not require invasive cell loading procedures. The system was then applied to the cell model of the human lung tumor cell line A549, in which exogenous CFTR was expressed by infecting with the replication-deficient recombinant adenovirus AdCFTR. DiSBAC2(3) was able to detect the fraction of cells in which the expression of CFTR protein was confirmed by immunocytochemistry. The DiSBAC2(3) probe was also used in human nasal respiratory cells cultured in vitro, in which it efficiently discriminated between endogenous CFTR in normal and CF cells. Functional evaluation of CFTR function by the described method can be a useful tool to detect the expression of the CF gene transferred by adenoviral vectors for use in gene therapy trials.

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