Reduction of connexin 37 expression by RNA interference decreases atherosclerotic plaque formation.

The aim of this study was to examine the effects of connexin 37 (Cx37) interference on atherosclerotic plaques. Lentiviruses expressing small interfering RNA (siRNA) of Cx37 were constructed, and were shown to significantly knockdown the mRNA and protein expression of Cx37 in vitro. Sixty pigs on a high-fat diet were randomly divided into three treatment groups of saline, mock or Cx37 siRNA, to induce plaque formation. The Cx37 lentiviral suspension was transfected into the abdominal aortic plaques of pigs. Plaque characteristics were detected by intravascular ultrasound and the expression of Cx37 mRNA was detected by semi-quantitative polymerase chain reaction. The expression of Cx37 protein was analyzed by western blot analysis. Two months after lentivirus transfection, Cx37 mRNA levels were decreased by 38% in the Cx37 siRNA group, by 60% in the mock-siRNA group and by 63% in the saline group (P<0.05). The mock group showed no significant changes in Cx37 expression as compared with the saline group. Cx37 protein expression was lower in the Cx37 siRNA-treated group as compared with the other groups (0.21 +/- 0.07 vs. 0.65 +/- 0.06 vs. 0.54 +/- 0.07). The percentage of plaque necrosis at 10 months (two months following RNAi) was decreased in the Cx37 siRNA group as compared with that at eight months, prior to RNAi (5.26 +/- 2.11 vs. 7.83 +/- 1.03%, P<0.05). In the mock-siRNA and saline groups, no differences (P=0.074, 0.061, respectively) were observed. In the Cx37 siRNA group, plaque volumes following 10 months decreased relative to those following eight months, prior to RNAi (21.03 +/- 6.24 vs. 31.23 +/- 10.23, P<0.01). By contrast, in the mock siRNA and saline groups, plaque volumes after 10 months were increased relative to those following eight months (38.54 +/- 13.56 vs. 32.12 +/- 11.21 mm(3), 37.36 +/- 14.21 vs. 30.21 +/- 12.02 mm(3), P=0.031, P=0.027). Atherosclerotic plaque formation was effectively decreased through the downregulation of Cx37 mRNA using Cx37 siRNA.