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Updated: Jul 7, 2026
Quantification of Atherosclerosis in Mice
Published on: June 12, 2019
Vaccination against CD99 inhibits atherogenesis in low-density lipoprotein receptor-deficient mice
Eva J A van Wanrooij1, Paula de Vos, M Gabriele Bixel
1Division of Biopharmaceutics, Leiden/Amsterdam Center for Drug Research, Gorlaeus Laboratories, PO Box 9502, 2300 RA Leiden, The Netherlands.
Insights
This study developed a CD99 DNA vaccine to target atherosclerosis. Vaccination reduced atherosclerotic lesions by blocking CD99 function and decreasing leukocyte recruitment.
Area of Science:
- Immunology
- Cardiovascular Research
- Molecular Biology
Background:
- Murine CD99 is expressed on leukocytes and endothelial cells, particularly at inter-endothelial contacts.
- Antibodies blocking CD99 inhibit leukocyte extravasation to inflamed sites in vivo.
- CD99's role in atherosclerosis warrants investigation.
Purpose of the Study:
- To investigate the role of CD99 in atherosclerosis.
- To develop and evaluate a CD99 vaccination protocol to block CD99 function in atherosclerosis.
Main Methods:
- Constructed a DNA vaccine targeting the extracellular domain of murine CD99.
- Administered the vaccine orally via attenuated Salmonella typhimurium.
- Assessed CD99 expression on vascular endothelium and leukocytes.
- Evaluated CD8-mediated cytotoxic responses and T cell activation.
- Quantified atherosclerotic lesion formation in aortic valve leaflets and carotid arteries.
Main Results:
- CD99 is expressed on vascular endothelium overlying atherosclerotic plaques and is upregulated by western-type diet.
- CD99 vaccination induced CD8+ T cells cytotoxic against CD99-expressing cells.
- Vaccination significantly attenuated atherosclerotic lesion formation (38% in aortic valve, 69% in carotid artery).
- Reduced leukocyte numbers in lesions and decreased CD99 expression on leukocytes were observed.
Conclusions:
- Vaccination against CD99 effectively decreases atherogenesis.
- Selective removal of CD99-expressing cells reduces leukocyte recruitment into atherosclerotic lesions.
- CD99 blockade represents a potential therapeutic strategy for attenuating atherosclerosis.
Aims:
Murine CD99 was recently found to be expressed on leukocytes and endothelial cells, where it is concentrated at inter-endothelial contacts. Blockade of CD99 by specific antibodies inhibits leukocyte extravasation to inflamed sites in vivo. The aim of the present study is to show the role of CD99 in atherosclerosis using a CD99 vaccination protocol to block the function of CD99 during atherosclerosis.
Methods And Results:
We constructed a DNA vaccine against CD99 by cloning the extracellular domain of murine CD99 into pcDNA3. Vaccination was performed by oral administration of attenuated Salmonella typhimurium transformed with pcDNA3-CD99. This vaccination results in a CD99-specific, CD8-mediated cytotoxic response and subsequent reduction of CD99-expressing cells. We showed that CD99 is expressed on vascular endothelium overlying atherosclerotic plaques and found that CD99 expression is upregulated during western-type diet feeding. CD99 vaccination induced the formation of CD8-positive T cells that were cytotoxic against cells transfected with pcDNA3-CD99. Activation of CD8(+) T cells was demonstrated by a 30% increase in CD8(+)CD69(+) double-positive T cells in spleen and mediastinal lymph nodes. Furthermore, lymphocytes isolated from CD99-vaccinated mice specifically lysed CD99-expressing cells. More importantly, vaccination against CD99 attenuated atherosclerotic lesion formation in the aortic valve leaflets by 38% and in the carotid artery by 69% compared with mice that were vaccinated with a control vector. Furthermore, a lower number of cells were found in atherosclerotic lesions, implying that fewer leukocytes were recruited to these sites. These observations were accompanied by a decrease in CD99 expression on leukocytes.
Conclusion:
We conclude that vaccination against CD99 decreases atherogenesis by the selective removal of CD99-expressing cells, which could reduce leukocyte recruitment into atherosclerotic lesions and attenuate atherogenesis.
