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 CD4+LAP+ Tregs in inhibiting inflammation and preventing atherosclerosis.Methods and results: Depletion of CD4+LAP+ Tregs results in aggravated inflammation and atherosclerotic lesions. Mechanistically, CD4+LAP+ 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 CD4+LAP+ Tregs to ApoE-/-mice or CD4-/-ApoE-/-mice led to decreased atherosclerotic lesions. Compared with control animals, adoptive transfer of CD4+LAP+ Tregs induced M2-like macrophage differentiation within the athero-sclerotic lesion and spleen, associated with increased collagen and alpha-SMA in plaques and decreased expression of MMP-2 and MMP-9. Mechanistic studies reveal that isolated CD4+LAP+ Tregs exhibit a tolerance phenotype, with increased expression of inhibitory cytokines and coinhibitory molecules. After coculture with CD4+LAP+ 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-1 beta and TNF-alpha, which was almost abrogated by transwell and partially TGF-beta 1 neutralization. RNA-seq analysis showed different gene expression profiles be-tween CD4+LAP+ Tregs and LAP-CD4+ T cells and between CD4+LAP+ Tregs of ApoE-/-mice and CD4+LAP+ Tregs of C57BL/6 mice, of which Fancd2 and IL4i1 may contribute to the powerful inhibitory properties of CD4+LAP+ Tregs. Furthermore, the number and the suppressive properties of CD4+LAP+ Tregs were impaired by oxLDL. Conclusions: Our data indicate that the remaining CD4+LAP+ Tregs play a protective role in atherosclerosis by modulating monocyte/macrophage differentiation and regulatory factors, which may partly explain the pro-tective effect of T cells tolerance in atherosclerosis. Moreover, adoptive transfer of CD4+LAP+ Tregs constitutes a novel approach to treat atherosclerosis.

Automated summary

CD4+LAP+ T cells play a protective role in preventing atherosclerosis by modulating monocyte/macrophage differentiation and regulatory factors.