Identifying Key Pathways and Components in Chemokine-Triggered T Lymphocyte Arrest Dynamics Using a Multi-Parametric Global Sensitivity Analysis.

Introduction: The arrest of rolling T lymphocytes at specific locations is crucial to proper immune response function. We previously developed a model of chemokine-driven integrin activation, termed integrative signaling adhesive dynamics (ISAD). In addition, we have shown that loss of diacylglycerol kinase (DGK) leads to a gain of function regarding adhesion under shear flow. We undertook this study to understand the sensitivity of adhesion to perturbations in other signaling molecules. Methods: We adapted multi-parametric sensitivity analysis (MPSA) for use in our ISAD model to identify important parameters, including initial protein concentrations and kinetic rate constants, for T lymphocyte arrest. We also compared MPSA results to those obtained from a single parametric sensitivity analysis. Results: In addition to the previously shown importance of DGK in lymphocyte arrest, PIP2 cleavage and Rap1 activation are crucial in determining T cell arrest dynamics, which agree with previous experimental findings. The l-selectin density on the T lymphocyte surface also plays a large role in determining the distance rolled before arrest. Both the MPSA and single-parametric method returned similar results regarding the most sensitive kinetic rate constants. Conclusion: We show here that the regulation of the amount of second messengers are, in general, more critical for determining T lymphocyte arrest over the initial signaling proteins, highlighting the importance of amplification of signaling in cell adhesion responses. Overall, this work provides a mechanistic insight of the contribution of key pathways and components, thus may help to identify potential therapeutic targets for drug development against immune disorders. [ABSTRACT FROM AUTHOR]