Virus specific CD8+ T-cells accumulate, but do not recognize antigen, in the atherosclerotic lesion

Funding Acknowledgements

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): ERA CVD

Dutch Heart Foundation

Viral infections have been associated with the progression of atherosclerosis. CD8+ T-cells directed against common viruses, such as influenza and Epstein-Barr virus, have been detected inside of human atherosclerotic lesions. These virus specific CD8+ T-cells have been hypothesized to contribute to the development of atherosclerosis, however, their mechanism of action in the atherosclerotic lesion remains unclear. This study aimed to characterize the behavior of virus specific CD8+ T-cells in the atherosclerotic lesion.

The presence of virus specific CD8+ T-cells in atherosclerotic lesions was assessed by performing T-cell receptor (TCR)-β sequencing on human endarterectomy samples and patient matched blood samples (N=10). These TCRs were subsequently compared to known virus specific TCR sequences. Virus specific CD8+ T-cells seemed to accumulate in the atherosclerotic lesion (mean=3.5%), compared to patient matched blood samples (mean=2.0%) (p=0.053). Moreover, these virus specific CD8+ T-cells produced significantly more IFN-γ (p=0.0009) and Granzyme B (p=0.0038) in response to external stimuli, suggesting these T-cells may play a pro-inflammatory role in the pathogenesis of atherosclerosis.

To investigate if virus specific CD8+ T-cells can be stimulated in situ, the immunopeptidome of 51 pooled human plaques was determined and matched with various viral peptidomes. Only one peptide presented in the atherosclerotic lesions matched a viral peptidome, rendering almost all virus specific CD8+ T-cells in the lesion antigen non-specific.

In conclusion, virus specific CD8+ T-cells are enriched in atherosclerotic lesions and have an activated phenotype, compared to other plaque residing CD8+ T-cells. The absence of virus specific antigen presentation in the atherosclerotic lesion suggests that if these CD8+ T-cells contribute to inflammation, they do so in an antigen independent manner.

Granzyme B+ CD4+ T cells associate with an unstable plaque phenotype in advanced human atherosclerosis

Funding Acknowledgements

Type of funding sources: Foundation. Main funding source(s): The Dutch Heart Foundation

Cytotoxic CD4+ T cells have previously been found in peripheral blood of patients with coronary artery disease (1), however their occurrence in atherosclerotic plaques and their association with the pathophysiology of atherosclerosis has not been established.

Single-cell RNA sequencing was performed on human carotid atherosclerotic plaques of 18 patients to identify specific T cell populations (2). Next, human femoral and carotid atherosclerotic plaques (n=95) and matched blood samples (n=49) were analyzed by flow cytometry for the presence of CD4+GZMB+ T cells. Plaque morphology was assessed by Movat’s Pentachrome staining.

A distinct cytotoxic GZMB+ PRF1+ CD28- CD4+ T cell cluster was identified using single-cell RNA sequencing. Furthermore, flow cytometry analysis showed that the percentage of GZMB+CD4+ T cells was significantly elevated in plaque compared to blood (Blood: 12.17±2.0 vs. Plaque: 17.40±1.0; P=0.0002). Moreover, a significant positive correlation was observed between the percentage of GZMB+CD4+ T cells in blood versus plaque (P=0.031). In line with the proinflammatory character of these cells, we found a positive association of GZMB+CD4+ T cells (P=0.036) with necrotic core size, whereas no correlation was found with this subtype in the circulation.

In this study we have shown an enrichment of cytotoxic CD4+ T cells in atherosclerotic lesions, which positively correlate with necrotic core size. Future studies are aimed at elucidating the role of these cells in advanced atherosclerosis.

THE USE OF A STAGGERED HERRINGBONE MICROMIXER FOR THE PREPARATION OF RIGID LIPOSOMAL FORMULATIONS ALLOWS EFFICIENT ENCAPSULATION OF ANTIGEN AND ADJUVANT

Anionic liposomal formulations have previously shown to have intrinsic tolerogenic capacity and these properties have been related to the rigidity of the particles. The combination of highly rigid anionic liposomes to deliver tolerogenic adjuvants and antigen peptides has potential applications for the treatment of autoimmune and inflammatory diseases. However, the preparation of these highly rigid anionic liposomes using traditional methods such as lipid film hydration presents problems in terms of scalability and loading efficiency of some costly tolerogenic adjuvants like 1-α,25-dihydroxyvitaminD3. Here we propose the use of an off-the-shelf staggered herringbone micromixer for the preparation of these formulations and performed a systematic study on the effect of temperature and flow conditions on the size and polydispersity index of the formulations. Furthermore, we show that the system allows for the encapsulations of a wide variety of peptides and significantly higher loading efficiency of 1-α,25-dihydroxyvitaminD3 compared to the traditional lipid film hydration method, without compromising their non-inflammatory interaction with dendritic cells. Therefore, the microfluidics method presented here is a valuable tool for the preparation of highly rigid tolerogenic liposomes in a fast, size-tuneable and scalable manner.