IL4 and triple-A syndrome: However, the same authors also speculated that the anti-inflammatory IL-4, produced by the same NKT cells, is responsible for an increased expression of MMPs by vSMCs and macrophages, thereby contributing to the AAA development.[25] We now show that the activation of type I NKT cells by the specific ligands α-GalCer and OCH results in a significant upregulation in the expression of different matrix degrading proteinases by both vSMCs and macrophages.