T-Cell Immunoglobulin and Mucin Domain 3 Acts as a Negative Regulator of Atherosclerosis
Objective—Atherosclerosis is a chronic autoimmune-like disease in which lipids and fibrous elements accumulate in the arterial blood vessels. T cells are present within atherosclerotic plaques, and their activation is partially dependent on costimulatory signals, which can either provide positive or negative signals that promote T-cell activation or limit T-cell responses, respectively. T-cell immunoglobulin and mucin domain 3 (Tim-3) is a coinhibitory type 1 transmembrane protein that affects the function of several immune cells involved in atherosclerosis, such as monocytes, macrophages, effector T cells, and regulatory T cells. In the present study, we determined the role of Tim-3 in the development of atherosclerosis.
Approach and Results—Western-type diet–fed LDLr−/− mice were treated with an anti–Tim-3 antibody for 3 and 8 weeks. Anti–Tim-3 administration increased fatty streak formation with 66% and increased atherosclerotic plaque formation after 8 weeks with 35% in the aortic root and with 50% in the aortic arch. Furthermore, blockade of Tim-3 signaling increased percentages of circulating monocytes with 33% and lesional macrophages with 20%. In addition, anti–Tim-3 administration increased CD4+ T cells with 17%, enhanced their activation status, and reduced percentages of regulatory T cells with 18% and regulatory B cells with 37%.
Conclusions—It is known that Tim-3 acts as a negative regulator of both innate and adaptive immune responses, and in the present study, we show that anti–Tim-3 treatment augments lesion development, accompanied by an increase in the number of monocytes/macrophages and CD4+ T cells and by decreased regulatory T cells and regulatory B cells.
- Received December 14, 2012.
- Accepted August 20, 2013.
- © 2013 American Heart Association, Inc.