The participating signals and structures that enable primary immune cells migrating within dense tissues are not completely revealed until now. Especially in
autoimmune diseases, mostly unknown mechanisms facilitate autoreactive immune cells to migrate to endogenous tissues, infiltrating and harming organ-specific structures. In order to gain deeper insights into the migratory behavior of primary autoreactive immune cells, we examined peripheral blood-derived lymphocytes (PBLs) of horses with equine recurrent
uveitis (ERU), a spontaneous animal model for autoimmune
uveitis in humans. In this study, we used a three-dimensional
collagen I
hydrogel matrix and monitored live-cell migration of primary lymphocytes as a reaction to different
chemoattractants such as
fetal calf serum (FCS),
cytokines interleukin-4 (IL-4), and
interferon-γ (IFN-γ), and a specific
uveitis autoantigen, cellular
retinaldehyde binding protein (CRALBP). Through these experiments, we uncovered distinct differences between PBLs from ERU cases and PBLs from healthy animals, with significantly higher cell motility, cell speed, and straightness during migration of PBLs from ERU horses. Furthermore, we emphasized the significance of expression levels and cellular localization of
septin 7, a membrane-interacting
protein with decreased abundance in PBLs of autoimmune cases. To underline the importance of
septin 7 expression changes and the possible contribution to migratory behavior in autoreactive immune cells, we used
forchlorfenuron (FCF) as a reversible inhibitor of
septin structures. FCF-treated cells showed more directed migration through dense tissue and revealed aberrant
septin 7 and
F-actin structures along with different
protein distribution and translocalization of the latter, uncovered by immunochemistry. Hence, we propose that
septin 7 and interacting molecules play a pivotal role in the organization and regulation of cell shaping and migration. With our findings, we contribute to gaining deeper insights into the migratory behavior and
septin 7-dependent cytoskeletal reorganization of immune cells in organ-specific
autoimmune diseases.