P-Selectin or intercellular adhesion molecule (ICAM)-1 deficiency substantially protects against atherosclerosis in apolipoprotein E-deficient mice.

The expression of leukocyte and endothelial cell adhesion molecules (CAMs) is essential for the emigration of leukocytes during an inflammatory response. The importance of the inflammatory response in the development of atherosclerosis is indicated by the increased expression of adhesion molecules, proinflammatory cytokines, and growth factors in lesions and lesion-prone areas and by protection in mice deficient in various aspects of the inflammatory response. We have quantitated the effect of deficiency for intercellular adhesion molecule (ICAM)-1, P-selectin, or E-selectin on atherosclerotic lesion formation at 20 wk of age in apolipoprotein (apo) E(-/-) (deficient) mice fed a normal chow diet. All mice were apo E(-/-) and CAM(+/+) or CAM(-/-) littermates, and no differences were found in body weight or cholesterol levels among the various genotypes during the study. ICAM-1(-/-) mice had significantly less lesion area than their ICAM-1(+/+) littermates: 4.08 +/- 0.70 mm(2) for -/- males vs. 5.87 +/- 0.66 mm(2) for +/+ males, and 3.95 +/- 0. 65 mm(2) for -/- females vs. 5.59 +/- 1.131 mm(2) for +/+ females, combined P < 0.0001. An even greater reduction in lesion area was observed in P-selectin(-/-) mice: 3.06 +/- 1.04 mm(2) for -/- males vs. 5.09 +/- 1.22 mm(2) for +/+ males, and 2.85 +/- 1.26 mm(2) for -/- females compared with 5.60 +/- 1.19 mm(2) for +/+ females, combined P < 0.001. The reduction in lesion area for the E-selectin null mice, although less than that seen for ICAM-1 or P-selectin, was still significant (4.54 +/- 2.14 mm(2) for -/- males vs. 5.92 +/- 0.63 mm(2) for +/+ males, and 4.38 +/- 0.85 mm(2) for -/- females compared with 5.94 +/- 1.44 mm(2) for +/+ females, combined P < 0.01). These results, coupled with the closely controlled genetics of this study, indicate that reductions in the expression of P-selectin, ICAM-1, or E-selectin provide direct protection from atherosclerotic lesion formation in this model.

Administration of helper-dependent adenoviral vectors and sequential delivery of different vector serotype for long-term liver-directed gene transfer in baboons.

The efficiency of first-generation adenoviral vectors as gene delivery tools is often limited by the short duration of transgene expression, which can be related to immune responses and to toxic effects of viral proteins. In addition, readministration is usually ineffective unless the animals are immunocompromised or a different adenovirus serotype is used. Recently, adenoviral vectors devoid of all viral coding sequences (helper-dependent or gutless vectors) have been developed to avoid expression of viral proteins. In mice, liver-directed gene transfer with AdSTK109, a helper-dependent adenoviral (Ad) vector containing the human alpha(1)-antitrypsin (hAAT) gene, resulted in sustained expression for longer than 10 months with negligible toxicity to the liver. In the present report, we have examined the duration of expression of AdSTK109 in the liver of baboons and compared it to first-generation vectors expressing hAAT. Transgene expression was limited to approximately 3-5 months with the first-generation vectors. In contrast, administration of AdSTK109 resulted in transgene expression for longer than a year in two of three baboons. We have also investigated the feasibility of circumventing the humoral response to the virus by sequential administration of vectors of different serotypes. We found that the ineffectiveness of readministration due to the humoral response to an Ad5 first-generation vector was overcome by use of an Ad2-based vector expressing hAAT. These data suggest that long-term expression of transgenes should be possible by combining the reduced immunogenicity and toxicity of helper-dependent vectors with sequential delivery of vectors of different serotypes.