The adaptive immune system protects us from infectious viruses and other microbes. Cells of the adaptive immune system - lymphocytes and antigen-presenting cells (APC) - are highly organized in strategic tissue locations throughout the body, the secondary lymphoid organs.
The roles of SLO are i) to filter pathogens from blood and lymph, thereby retaining their spread through the body; ii) to present pathogens or derived peptides to antigen-specific lymphocytes; and iii) to create microenvironments, which regulate the differentiation and survival of antigen-specific lymphocytes.
The stromal cells which form the scaffold of T and B cell zones, the fibroblastic reticular cells (FRC) and follicular dendritic cells (FDC), respectively, are now recognized to participate in all of these processes.
Novel imaging techniques such as twophoton microscopy (2PM), which allows to directly observe the dynamic behavior of lymphocytes in PLN of live, anesthetized mice, have uncovered a role of FRC as contact guidance cues for migrating lymphocytes. Nonetheless, there is a lack of scientific knowledge on the role of stromal cells in homeostasis and antiviral immunity. Here, we propose to develop new transgenic mouse models to study the role of T cell zone stromal cells during homeostasis and antiviral immune responses. These studies will include intense collaboration between the groups of Dr. Stein (Subproject A - 2PM and lymphocyte trafficking) and Prof. Ludewig (Subproject B - viral immunology and transgenic mouse development).
SLO are dynamic structures, which expand and decrease in size in the course of an immune response. As the mechanisms of stromal restructuring have remained elusive, a comprehensive and quantitative analysis of the global 3D SLO anatomy using mesoscopic imaging techniques, such as Optical Projection Tomography (OPT) and selective plane illumination microscopy (SPIM) is highly desirable.We therefore propose to develop a hybrid OPT/SPIM scanner in collaboration with Dr. Sharpe, who had previously developed OPT. This project will entail a close collaboration with Dr. Stein (Subproject A) and Dr. Sharpe (Subproject C), with an emphasis on the global visualization of stromal cells in homeostasis and antiviral immune responses in transgenic mouse models developed by Prof. Ludewig (Subproject B). Using the newly developed OPT/SPIM scanner, these studies will also include a comprehensive analysis of morphogenetic factors governing vascular remodeling in antiviral immunity. In summary, our proposal aims to address the immunological relevance of lympoid stromal elements with novel imaging methods.