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Mathematical Modeling and Analysis of CD200-CD200R in Cancer Treatment
Kang-Ling Liao1, Kenton D Watt2
1Department of Mathematics, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada. Kang-Ling.Liao@umanitoba.ca.
Abstract:
CD200 is a cell membrane protein that binds to its receptor, CD200 receptor (CD200R). The CD200 positive tumor cells inhibit the cellular functions of M1 and M2 macrophages and dendritic cells (DCs) through the CD200-CD200R complex, resulting in downregulation of Interleukin-10 and Interleukin-12 productions and affecting the activation of cytotoxic T lymphocytes. In this work, we provide two ordinary differential equation models, one complete model and one simplified model, to investigate how the binding affinities of CD200R and the populations of M1 and M2 macrophages affect the functions of the CD200-CD200R complex in tumor growth. Our simulations demonstrate that (i) the impact of the CD200-CD200R complex on tumor promotion or inhibition highly depends on the binding affinity of the CD200R on M2 macrophages and DCs to the CD200 on tumor cells, and (ii) a stronger binding affinity of the CD200R on M1 macrophages or DCs to the CD200 on tumor cells induces a higher tumor cell density in the CD200 positive tumor. Thus, the CD200 blockade would be an efficient treatment method in this case. Moreover, the simplified model shows that the binding affinity of CD200R on macrophages is the major factor to determine the treatment efficacy of CD200 blockade when the binding affinities of CD200R on M1 and M2 macrophages are significantly different to each other. On the other hand, both the binding affinity of CD200R and the population of macrophages are the major factors to determine the treatment efficacy of CD200 blockade when the binding affinities of CD200R on M1 and M2 macrophages are close to each other. We also analyze the simplified model to investigate the dynamics of the positive and trivial equilibria of the CD200 positive tumor case and the CD200 deficient tumor case. The bifurcation diagrams show that when M1 macrophages dominate the population, the tumor cell density of the CD200 positive tumor is higher than the one of CD200 deficient tumor. Moreover, the dynamics of tumor cell density change from tumor elimination to tumor persistence to oscillation, as the maximal proliferation rate of tumor cells increases.
Insights
The CD200-CD200R complex impacts tumor growth, with binding affinity on M2 macrophages and dendritic cells being key. CD200 blockade shows promise as a cancer treatment, especially when M1 macrophage binding affinity differs significantly.
Area of Science:
- Immunology
- Mathematical Biology
- Computational Oncology
Background:
- CD200 is a cell membrane protein interacting with its receptor, CD200R.
- The CD200-CD200R complex influences M1/M2 macrophages and dendritic cells, affecting cytokine production and T cell activation.
- Tumor cells utilize CD200 to modulate the immune microenvironment.
Purpose of the Study:
- To model the CD200-CD200R complex's role in tumor growth using ordinary differential equations.
- To investigate the influence of CD200R binding affinities and macrophage populations on tumor dynamics.
- To evaluate the potential of CD200 blockade as a therapeutic strategy.
Main Methods:
- Development of two ordinary differential equation models: a complete and a simplified version.
- Simulation analysis to explore the effects of binding affinities and cell populations.
- Bifurcation analysis to study tumor equilibria and dynamics under varying conditions.
Main Results:
- Tumor growth modulation by the CD200-CD200R complex is highly dependent on CD200R binding affinity on M2 macrophages and dendritic cells.
- Increased CD200R binding affinity on M1 macrophages or dendritic cells correlates with higher tumor cell density in CD200-positive tumors.
- Macrophage CD200R binding affinity is crucial for CD200 blockade efficacy, particularly when M1 and M2 affinities differ significantly.
Conclusions:
- CD200 blockade is a potential cancer treatment strategy, especially when specific binding affinities are present.
- Macrophage population dynamics and CD200R binding affinity are key determinants of CD200 blockade effectiveness.
- M1 macrophage dominance can lead to higher tumor cell density in CD200-positive tumors, with dynamics ranging from elimination to oscillation.
