Differences in local immune cell landscape between Q fever and atherosclerotic abdominal aortic aneurysms identified by multiplex immunohistochemistry

Adventitial adaptive immune cells are associated with ascending aortic dilatation in patients with a bicuspid aortic valve

Background

Bicuspid aortic valve (BAV) is associated with ascending aorta aneurysms and dissections. Presently, genetic factors and pathological flow patterns are considered responsible for aneurysm formation in BAV while the exact role of inflammatory processes remains unknown.

Methods

In order to objectify inflammation, we employ a highly sensitive, quantitative immunohistochemistry approach. Whole slides of dissected, dilated and non-dilated ascending aortas from BAV patients were quantitatively analyzed.

Results

Dilated aortas show a 4-fold increase of lymphocytes and a 25-fold increase in B lymphocytes in the adventitia compared to non-dilated aortas. Tertiary lymphoid structures with B cell follicles and helper T cell expansion were identified in dilated and dissected aortas. Dilated aortas were associated with an increase in M1-like macrophages in the aorta media, in contrast the number of M2-like macrophages did not change significantly.

Conclusion

This study finds unexpected large numbers of immune cells in dilating aortas of BAV patients. These findings raise the question whether immune cells in BAV aortopathy are innocent bystanders or contribute to the deterioration of the aortic wall.

Topography of immune cell infiltration in different stages of coronary atherosclerosis revealed by multiplex immunohistochemistry

Background

Aim of this study was to investigate immune cells and subsets in different stages of human coronary artery disease with a novel multiplex immunohistochemistry (mIHC) technique.

Methods

Human left anterior descending coronary artery specimens were analyzed: eccentric intimal thickening (N = 11), pathological intimal thickening (N = 10), fibroatheroma (N = 9), and fibrous plaque (N = 9). Eccentric intimal thickening was considered normal, and pathological intimal thickening, fibroatheroma, and fibrous plaque were considered diseased coronary arteries. Two mIHC panels, consisting of six and five primary antibodies, autofluoresence, and DAPI, were used to detect adaptive and innate immune cells. Via semi-automated analysis, (sub)types of immune cells in whole plaques and specific plaque regions were quantified.

Results

Increased numbers of CD3⁺ T cells (P < 0.001), CD20⁺ B cells (P = 0.013), CD68⁺ macrophages (P = 0.003), CD15⁺ neutrophils (P = 0.017), and CD31⁺ endothelial cells (P = 0.024) were identified in intimas of diseased coronary arteries compared to normal. Subset analyses of T cells and macrophages showed that diseased coronary arteries contained an abundance of CD3⁺CD8^- non-cytotoxic T cells and CD68⁺CD206^- non-M2-like macrophages. Proportions of CD3⁺CD45RO⁺ memory T cells were similar to normal coronary arteries. Among pathological intimal thickening, fibroatheroma, and fibrous plaque, all immune cell numbers and subsets were similar.

Conclusions

The type of immune response does not differ substantially between different stages of plaque development and may provide context for mechanistic research into immune cell function in atherosclerosis. We provide the first comprehensive map of immune cell subtypes across plaque types in coronary arteries demonstrating the potential of mIHC for vascular research.