Low Numbers of FOXP3 Positive Regulatory T Cells Are Present in all Developmental Stages of Human Atherosclerotic Lesions

BACKGROUND: T cell mediated inflammation contributes to atherogenesis and the onset of acute cardiovascular disease. Effector T cell functions are under a tight control of a specialized T cell subset, regulatory T cells (Treg). At present, nothing is known about the in situ presence of Treg in human atherosclerotic tissue. In the present study we investigated the frequency of naturally occurring Treg cells in all developmental stages of human atherosclerotic lesions including complicated thrombosed plaques. METHODOLOGY: Normal arteries, early lesions (American Heart Association classification types I, II, and III), fibrosclerotic plaques (types Vb and Vc) and 'high risk' plaques (types IV, Va and VI) were obtained at surgery and autopsy. Serial sections were immunostained for markers specific for regulatory T cells (FOXP3 and GITR) and the frequency of these cells was expressed as a percentage of the total numbers of CD3+ T cells. Results were compared with Treg counts in biopsies of normal and inflammatory skin lesions (psoriasis, spongiotic dermatitis and lichen planus). PRINCIPLE FINDINGS: In normal vessel fragments T cells were virtually absent. Treg were present in the intima during all stages of plaque development (0.5-5%). Also in the adventitia of atherosclerotic vessels Treg were encountered, in similar low amounts. High risk lesions contained significantly increased numbers of Treg compared to early lesions (mean: 3.9 and 1.2%, respectively). The frequency of FOXP3+ cells in high risk lesions was also higher compared to stable lesions (1.7%), but this difference was not significant. The mean numbers of intimal FOXP3 positive cells in atherosclerotic lesions (2.4%) was much lower than those in normal (24.3%) or inflammatory skin lesions (28%). CONCLUSION: Low frequencies of Treg in all developmental stages of human plaque formation could explain the smoldering chronic inflammatory process that takes place throughout the longstanding course of atherosclerosis

Microvascular endoglin (CD105) expression correlates with tissue markers for atherosclerotic plaque vulnerability in an ageing population with multivessel coronary artery disease

Li X, van der Meer J J, van der Loos C M, Ploegmakers H J P, de Boer O J, de Winter R J & van der Wal A C ?(2012) Histopathology similar to 61, 8897 Microvascular endoglin (CD105) expression correlates with tissue markers for atherosclerotic plaque vulnerability in an ageing population with multivessel coronary artery disease Aims: Vulnerable atherosclerotic plaques are lesions with a high propensity to develop plaque disruption and superimposed thrombosis. No systematic studies have been carried out on tissue markers for plaque vulnerability throughout the entire coronary artery system at the end stages of coronary atherosclerosis. Methods and results: Nine autopsied patients (mean age 77 years) with angiographically severe trivascular coronary atherosclerosis were selected for this study. All visible lesions in postmortem coronary angiograms (n = 125) were histologically and immunohistochemically screened for the presence of intraplaque haemorrhages (activated) microvessels and inflammatory infiltrates. Intraplaque haemorrhages were observed in 76/125 plaques (61%). Chronic inflammation was found superficially in 59/125 plaques (47%) and deeply inside the plaque tissue in 103/125 plaques (83%). Microvessels were found in 100/125 lesions (80%), of which 58% showed endothelial expression of the vascular activation marker CD105. Moreover, microvascular CD105 positivity correlated positively with plaque haemorrhage and deeply seated plaque inflammation. Conclusions: Plaque inflammation and haemorrhages can be found at a high frequency throughout the coronary artery system of elderly patients with multivessel coronary atherosclerosis. Microvascular expression of endoglin (CD105), which correlates positively with both of these features of plaque vulnerability, can serve as a marker of the risk of developing coronary thrombotic complication

Differential expression of interleukin-17 family cytokines in intact and complicated human atherosclerotic plaques

In addition to the classical TH1 and TH2 cytokines, members of the recently identified IL-17 cytokine family play an important role in regulating cellular and humoral immune responses. At present nothing is known about the role of these cytokines in atherosclerosis. Expression of IL-17A, -E and -F was investigated in atherosclerotic tissue by rtPCR and immunohistochemistry. IL-17E and its receptor were further studied in cultured smooth muscle cells and endothelial cells, using rtPCR and western blot. rtPCR showed that IL-17A, -E and -F were expressed in the majority of plaques under investigation. IL-17A/F was expressed by mast cells in all stages of plaque development. IL-17A/F+ neutrophils were always observed in complicated plaques, but hardly in intact lesions. IL-17A/F+ Tcells ('TH17') were never observed. IL-17E was expressed by smooth muscle cells and endothelial cells in both normal and atherosclerotic arteries, and in advanced plaques also extensively by mature B cells. Cultured smooth muscle cells and endothelial cells were found to express both IL-17E and its functional receptor (IL-17RB). The constitutive expression of IL-17E by resident plaque cells, and the additional presence of IL-17E(+) B cells and IL-17A/F+ neutrophils in advanced and complicated plaques indicates a complex contribution of IL-17 family cytokines in human atherosclerosis, depending on the stage and activity of the disease. Copyright (C) 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Lt

Histology of normal human artery.

<p>Hematoxylin&eosin overview (A, bar = 200 µm) and detailed CD3 (B, bar = 50 µm) staining of a normal human (mammary) artery. CD3 positive T cells are rare in normal human intima.</p

Histology of different types of atherosclerotic arteries.

<p>Hematoxylin&Eosin overview (A, E, I, bar = 200 µm) and detailed CD3 (B, F, J, bar = 50 µm), FOXP3(C, G, K) and GITR(D, H, L) stains of three different types of atherosclerotic lesions: AHA class II (A–D), AHA class Va (E–H) and AHA class VI (I–L). CD3 positive T cells are frequently present in atherosclerotic tissue, but Treg are scarce.</p

Double staining images after spectral imaging.

<p>A: FOXP3 (green) and CD3 (red) in atherosclerotic intima. Nuclei are depicted in blue. Inset shows double stained cell. Note nuclear staining of transcription factor FOXP3 and cytoplasmatic CD3 positivity; B: GITR (green) and CD3 (red) in atherosclerotic intima. Inset shows one double and one single stained cell; C: GITR (green) and CD3 (red) in atherosclerotic adventitia. GITR positive cells do not co-express CD3. D: GITR (green) and CD20 (red). No double stained cells. E: GITR (green) and CD138 (red). Inset shows double stained cells. F: GITR (green) and CD68 (red). No double stained cells.</p