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

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.

To investigate the function of CD4⁺LAP⁺ Tregs in inhibiting inflammation and preventing atherosclerosis.

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 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 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-1β and TNF-α, which was almost abrogated by transwell and partially TGF-β1 neutralization. RNA-seq analysis showed different gene expression profiles between 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.

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 protective effect of T cells tolerance in atherosclerosis. Moreover, adoptive transfer of CD4⁺LAP⁺ Tregs constitutes a novel approach to treat atherosclerosis.