Invariant natural killer T cells and obesity

Abstract

Invariant natural killer T cells (iNKT cells) are special kinds of T lymphocyte subset which widely distributed in liver, spleen, bone marrow and other tissues. In 2009, Lynch et al first reported the presence of iNKT cells in human omental adipose tissue, and its surface markers were quite different from that of the iNKT cells dwelled in other peripheral tissues. Once activated, iNKT cells are capable of regulating the immunological microenvironment within adipose tissue. It is reported that numbers of iNKT cells in adipose tissue were significantly decreased in obese patients and high fat diet-induced obese mice.However, the amount of iNKT cells can be restored after weight loss. Studies showed that the mice models lacking iNKT cells were more likely to gain weight. The levels of pro-inflammatory macrophages and cytokines in adipose tissue were increased and metabolic abnormalities such as impaired glucose tolerance were observed. The activation of iNKT cells in mice was found to be able to promote browning of white adipose tissue, which then increased heat production and subsequently led to weight loss. Therefore, due to the close relationship among iNKT cells, adipose tissue inflammation and obesity, it is expected that iNKT cells can be utilized as a promising target in the treatment of obesity and related metabolic abnormalities in the future. Key words: Invariant natural killer T cells; Obesity; Adipose tissue; Inflammation; Macrophages