Latency-associated peptide (LAP)CD4 regulatory T cells prevent atherosclerosis by modulating macrophage polarization.

RATIONALE

A persistent autoimmune and inflammatory response plays a critical role in the progression of atherosclerosis. The transcription factor forkhead box P3 (Foxp3)CD4 regulatory T cells (Foxp3 Tregs) attenuate atherosclerosis. Latency-associated peptide (LAP)CD4 T cells are a new class of Tregs whose role in atherosclerosis is unknown.

OBJECTIVE

To investigate the function of CD4LAP Tregs in inhibiting inflammation and preventing atherosclerosis.

METHODS AND RESULTS

Depletion of CD4LAP Tregs results in aggravated inflammation and atherosclerotic lesions. Mechanistically, CD4LAP Treg depletion was associated with decreased M2-like macrophages and increased Th1 and Th17 cells, characterized by increased unstable plaque promotion and decreased expression of inflammation-resolving factors in both arteries and immune organs. In contrast, adoptive transfer of CD4LAP Tregs to ApoE mice or CD4ApoE mice led to decreased atherosclerotic lesions. Compared with control animals, adoptive transfer of CD4LAP Tregs induced M2-like macrophage differentiation within the atherosclerotic lesion and spleen, associated with increased collagen and α-SMA in plaques and decreased expression of MMP-2 and MMP-9. Mechanistic studies reveal that isolated CD4LAP Tregs exhibit a tolerance phenotype, with increased expression of inhibitory cytokines and coinhibitory molecules. After coculture with CD4LAP Tregs, monocytes/macrophages display typical features of M2 macrophages, including upregulated expression of CD206 and Arg-1 and decreased production of MCP-1, IL-6, IL-1β and TNF-α, which was almost abrogated by transwell and partially TGF-β1 neutralization. RNA-seq analysis showed different gene expression profiles between CD4LAP Tregs and LAPCD4 T cells and between CD4LAP Tregs of ApoE mice and CD4LAP Tregs of C57BL/6 mice, of which Fancd2 and IL4i1 may contribute to the powerful inhibitory properties of CD4LAP Tregs. Furthermore, the number and the suppressive properties of CD4LAP Tregs were impaired by oxLDL.

CONCLUSIONS

Our data indicate that the remaining CD4LAP Tregs play a protective role in atherosclerosis by modulating monocyte/macrophage differentiation and regulatory factors, which may partly explain the protective effect of T cells tolerance in atherosclerosis. Moreover, adoptive transfer of CD4LAP Tregs constitutes a novel approach to treat atherosclerosis.