Deficiency of invariant Vα14 natural killer T cells decreases atherosclerosis in LDL receptor null mice

Aims CD1d-restricted natural killer T (NKT) cells function by regulating numerous immune responses during innate and adaptive immunity. Depletion of all populations of CD1d-dependent NKTcells has been shown by several groups to reduce atherosclerosis in two different mouse models of the disease. In this study, we determined if removal of a single (V alpha 14) NKTcell population protects mice from the disease. Methods and results Targeted deletion of the J alpha 18 gene results in selective depletion of CD1d-dependent V alpha 14 NKTcells in C57BL/6 mice without affecting the population of other NKT, NK, and conventional Tcells. Therefore, to study the effect of V alpha 14 NKTcell depletion on the progression of atherosclerosis, we examined the extent of lesion formation using paired littermate LDL receptor null. mice that were either (+/+) or (-/-) for the J alpha 18 gene following the feeding of these mice a cholesterol- and fat-enriched diet for 8 weeks. At the end of the study, we found no difference in either serum total- or lipoprotein-cholesterol distributions between groups. However, quantification of atherosclerosis revealed that V alpha 14 NKT cell deficiency significantly decreased lesion size in the aortic root (20-28%) and arch (28-38%) in both genders of mice. By coupling the techniques of laser capture microdissection with quantitative real-time RT-PCR, we found that expression of the proatherogenic cytokine interferon (IFN)-gamma was significantly reduced in lesions from J alpha 18(-/-) mice. Conclusion This study is the first to identify a specific subpopulation of NKT cells that promotes atherosclerosis via a mechanism appearing to involve IFN-gamma expression.