Increased Level of Tim-3 + PD-1 + CD4 + T Cells With Altered Function Might Be Associated With Lower Extremity Arteriosclerosis Obliterans.

Lower extremity arteriosclerosis obliterans (LEASO) is a vascular disease that may result in adult limb loss worldwide. CD4 ⁺ T cell-mediated immunity plays a significant role in LEASO. The T cell immunoglobulin and mucin domain 3 (Tim-3) and inhibitory receptor programmed cell death-1 (PD-1) are well-known immune checkpoints that play crucial roles in regulating CD4 ⁺ T cell activation or tolerance. In this study, blood mononuclear cells were isolated from the blood samples of healthy controls and patients who were diagnosed with LEASO for the first time [stage III or IV according to the Fontaine classification system and had not received drugs (except for heparin) or surgery treatment]. We concluded the higher proportion of Tim-3 ⁺ PD-1 ⁺ CD4 ⁺ T cells in human higher stage LEASO, and oxidized low-density lipoprotein increased Tim-3 and PD-1 co-expression by activating CD4 ⁺ T cells in a dose- dependent manner. Tim-3 ⁺ PD-1 ⁺ CD4 ⁺ T cells displayed a more active status and produced more anti-atherogenic cytokines compared to Tim-3 ^- PD-1 ^- CD4 ⁺ T cells. Apart from the increased frequency, the altered function of Tim-3 ⁺ PD-1 ⁺ CD4 ⁺ T cells was also observed in LEASO compared to those from healthy controls. These in vitro results indicated that Tim-3 and PD-1 might be promising early warning targets of higher stage LEASO. In addition, the blockade of Tim-3 and PD-1 signaling pathways aggravated the pro-atherogenic Th1 responses in LEASO, further suggesting that the cardiovascular safety must be a criterion considered in using immune checkpoint inhibitors to reverse T cell exhaustion during tumors and chronic viral infections.
Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
(Copyright © 2022 Cui, Chen, Dai, Ou, Qiu and Wang.)