Final Report Summary - MITISCD36LTA (The role of glycoprotein CD36 as a platelet receptor for Streptococci and Staphylococci)
MITISCD36LTA (268319)
This funding provided €50,000 of which ~€45,000 was spent over the 24 month duration of the project. This contributed to research costs and contributed to the student stipend of Alyson Murray, a PhD student working on the project. The funding also allowed Dr. Jennifer Mitchell and Alyson Murray to present their research findings at conferences both in Ireland and internationally in Edinburgh, San Francisco and Italy and publish the research in international journals. The funding also allowed Dr. Mitchell to promote Marie Curie research and funding at outreach events to school going children, teenagers and adults as well as to researchers and college students.
Aims:
The aims of the project were:
Aim 1: To determine the region of CD36 to which Streptococcus mitis and its LTA bind.
Aim 2: Analysis of which component of S. mitis LTA CD36 recognises.
Aim 3: Assess the interaction of S. mitis and LTA with platelets and cells expressing CD36.
Results:
Aim 1: To determine the region of CD36 to which Streptococcus mitis and its LTA bind.
We have determined the region in CD36 to which streptococcus mitis and its LTA bind. This overlaps with the binding site for oxidised low density lipoprotein. This same region also appears to affect the binding of Staphylococcus aureus and other gram positive pathogens interacting with CD36 and may also promote attachment of gram negative bacteria with CD36.
Aim 2: Analysis of which component of S. mitis LTA CD36 recognises.
CD36 appears to preferentially interact with negatively charged glycolipid portion of LTA. Neutral LTA glycolipids interact with a lower affinity.
Aim 3: Assess the interaction of S. mitis and LTA with platelets and cells expressing CD36.
Bacterial LTA is recognised by CD36 on the surface of cells. Mutation of the binding site of CD36 for LTA prevents attachment of bacterial cells to mammalian cells expressing CS36 variants.
Conclusions
We have been able to identify the binding site in CD36 for bacterial LTA and have identified how LTA interacts with CD36. This has potential to provide therapeutic treatments for gram positive bacterial infections and to prevent colonisation of human mucosal surfaces with opportunistic pathogens that are difficult to treat with antibiotics.
Potential Impact and Use
This grant has had a very positive personal impact for me (Dr. Jennifer Mitchell) in that it has allowed me to take on two PhD students that were funded by UCD (€33,000) and Teagasc (€84,000). I have also been successful in attracting funding for a fellowship in Translational Medicine from the Health Research Board of Ireland (€90,368) to follow up research that has grown from the initial project funded by the MC IRG MITISCD36LTA (268319). The first PhD student is due to graduate next year and the second the following year. As such this modest 24 month investment has now contributed positively to the career development to three people.
I have also applied for funding from Science Foundation Ireland which, if successful, will hopefully contribute to my long term career integration and development. This application would fund myself, a 2 year postdoc and two four year PhD students to investigate the contribution of intravascular infection in the formation of atherosclerosis in patients with elevated triglyceide levels ie diabetic patients and patients on statins. This will be investigated by looking at the interaction of bacterial glycolipids with scavenger receptors on platelets and macrophages. We propose to elucidate the interaction of glycolipids form gram positive and gram negative bacteria with platelets and the contribution of this interaction to platelet binding and activation. In addition we propose to investigate the interaction of the same glycolipids with macrophages and the ability of these glycolipids and bacteria to stimulate foam cell formation in vitro and in ex vivo blood samples and analyse the contributions of these interactions to atherosclerotic lesion formation in mouse models of atherosclerosis and analyse whether blocking peptides can ameliorate the pro-atherogenic effect of the bloodstream bacteria
Socioeconomic impact
This project will have a potentially very significant socioeconomic impact by illustrating the role that transient bacteremias have on the promotion of atherosclerosis ie from dental caries. It is only in fully elucidating these interactions that we can start to reduce the levels of harmful vascular disease that is on the rise in diabetic patients, patients with metabolic disease and patients with elevated cholesterol and triglyceride levels.
This funding provided €50,000 of which ~€45,000 was spent over the 24 month duration of the project. This contributed to research costs and contributed to the student stipend of Alyson Murray, a PhD student working on the project. The funding also allowed Dr. Jennifer Mitchell and Alyson Murray to present their research findings at conferences both in Ireland and internationally in Edinburgh, San Francisco and Italy and publish the research in international journals. The funding also allowed Dr. Mitchell to promote Marie Curie research and funding at outreach events to school going children, teenagers and adults as well as to researchers and college students.
Aims:
The aims of the project were:
Aim 1: To determine the region of CD36 to which Streptococcus mitis and its LTA bind.
Aim 2: Analysis of which component of S. mitis LTA CD36 recognises.
Aim 3: Assess the interaction of S. mitis and LTA with platelets and cells expressing CD36.
Results:
Aim 1: To determine the region of CD36 to which Streptococcus mitis and its LTA bind.
We have determined the region in CD36 to which streptococcus mitis and its LTA bind. This overlaps with the binding site for oxidised low density lipoprotein. This same region also appears to affect the binding of Staphylococcus aureus and other gram positive pathogens interacting with CD36 and may also promote attachment of gram negative bacteria with CD36.
Aim 2: Analysis of which component of S. mitis LTA CD36 recognises.
CD36 appears to preferentially interact with negatively charged glycolipid portion of LTA. Neutral LTA glycolipids interact with a lower affinity.
Aim 3: Assess the interaction of S. mitis and LTA with platelets and cells expressing CD36.
Bacterial LTA is recognised by CD36 on the surface of cells. Mutation of the binding site of CD36 for LTA prevents attachment of bacterial cells to mammalian cells expressing CS36 variants.
Conclusions
We have been able to identify the binding site in CD36 for bacterial LTA and have identified how LTA interacts with CD36. This has potential to provide therapeutic treatments for gram positive bacterial infections and to prevent colonisation of human mucosal surfaces with opportunistic pathogens that are difficult to treat with antibiotics.
Potential Impact and Use
This grant has had a very positive personal impact for me (Dr. Jennifer Mitchell) in that it has allowed me to take on two PhD students that were funded by UCD (€33,000) and Teagasc (€84,000). I have also been successful in attracting funding for a fellowship in Translational Medicine from the Health Research Board of Ireland (€90,368) to follow up research that has grown from the initial project funded by the MC IRG MITISCD36LTA (268319). The first PhD student is due to graduate next year and the second the following year. As such this modest 24 month investment has now contributed positively to the career development to three people.
I have also applied for funding from Science Foundation Ireland which, if successful, will hopefully contribute to my long term career integration and development. This application would fund myself, a 2 year postdoc and two four year PhD students to investigate the contribution of intravascular infection in the formation of atherosclerosis in patients with elevated triglyceide levels ie diabetic patients and patients on statins. This will be investigated by looking at the interaction of bacterial glycolipids with scavenger receptors on platelets and macrophages. We propose to elucidate the interaction of glycolipids form gram positive and gram negative bacteria with platelets and the contribution of this interaction to platelet binding and activation. In addition we propose to investigate the interaction of the same glycolipids with macrophages and the ability of these glycolipids and bacteria to stimulate foam cell formation in vitro and in ex vivo blood samples and analyse the contributions of these interactions to atherosclerotic lesion formation in mouse models of atherosclerosis and analyse whether blocking peptides can ameliorate the pro-atherogenic effect of the bloodstream bacteria
Socioeconomic impact
This project will have a potentially very significant socioeconomic impact by illustrating the role that transient bacteremias have on the promotion of atherosclerosis ie from dental caries. It is only in fully elucidating these interactions that we can start to reduce the levels of harmful vascular disease that is on the rise in diabetic patients, patients with metabolic disease and patients with elevated cholesterol and triglyceride levels.