Understanding the Extracellular Matrix Structure of Lymph Nodes During Immune Reponse

Abstract

Lymph nodes (LNs) are integral in the human immune system, as they facilitate the movement of lymphocytes to areas of the body experiencing immunological challenges. During inflammation, research has shown that LNs expand up to 10 times their initial volumetric size and go through major changes. Most importantly, it is known that the extracellular matrix (ECM) of the LN contributes to its structure in addition to cell activities such as proliferation and migration. With the ECM being critical in LN function, we hope to understand how it changes throughout the stages of inflammation. To do this, we are optimizing a procedure to image lymph node samples and quantify the ECM’s interstitial spacing through the inflammatory response. While conducting this project, mice are injected with lipopolysaccharide (the cellular wall component of gram-negative bacteria), and LNs are collected during the 14-day inflammatory period. The tissue is sliced and stained using immunofluorescence. The images acquired from a confocal microscope are then processed using Fiji software and put into a gap analysis MATLAB code, provided by scientists at the Francis Crick Institute. After converting the interstitial space and ECM to zeros and ones (binary), the code quantifies the empty space and structures within the ECM. This information allows us to see how interstitial spacing within the ECM during inflammation correlates to the LNs’ mechanical properties. This insight into the inner workings of LNs will provide more details about their physiology and how changes in architecture, due to disease and age, can ultimately change LN immune function.