Suppression of atherogenesis by delivery of TGFβ1ACT using adeno-associated virus type 2 in LDLR knockout mice

TGFβ1 deficiency has been attributed to the development of atherosclerosis. There is, however, little direct evidence for this concept. To examine this hypothesis, low-density lipoprotein receptor knockout (LDLR−/−) mice were injected via tail vein with recombinant adeno-associated virus type 2 (rAAV) carrying a bioactive TGFβ1 mutant (AAV/TGFβ1ACT, n = 10) or granulocyte-macrophage-colony stimulating factor (AAV/GM-CSF, n = 10, a negative control) or saline (n = 9, control), and then put on a high cholesterol diet. At 18 weeks, blood lipids were found to be similarly elevated in all LDLR−/− mice. TGFβ1ACT and GM-CSF (DNA, mRNA, and protein) were highly expressed in the tissues of mice given TGFβ1ACT or AAV/GM-CSF, respectively, showing sustained transfection following gene delivery by the systemic route. Saline-treated and AAV/GM-CSF-treated LDLR−/− mice showed extensive areas of atherosclerotic lesion formation. There was evidence of intense oxidative stress (nitrotyrosine staining), inflammation (CD68 staining), and expression of adhesion molecules and the ox-LDL receptor LOX-1 (gene array analysis) in the atherosclerotic tissues. Importantly, atherosclerotic lesion formation was markedly inhibited in the LDLR−/− mice given AAV/TGFβ1ACT. Expression of adhesion molecules and LOX-1, oxidative stress, and inflammatory response all were inhibited in the mice given AAV/TGFβ1ACT (P < 0.05 vs. saline-treated or GM-CSF-treated LDLR−/− mice). These data for the first time demonstrate that systemic delivery of TGFβ1ACT gene via AAV can inhibit formation of atherosclerotic lesions, possibly via anti-inflammatory and anti-oxidant mechanisms. These findings suggest a novel view of TGFβ1 in atherogenesis and a potential new gene therapy for treatment of atherosclerosis.