A034 Meningeal immune cell dynamics in Huntington’s disease

<h3>Background</h3> Current research highlights involvement of the immune system and inflammation in Huntington’s disease (HD) pathogenesis, and positive effects in patients receiving immunomodulatory therapies are discussed. Challenging the role of the meninges solely as a protective CNS barrier, recent investigations revealed immune cells and lymphatic networks within the meninges. Meningeal immunity is now seen as crucial in homeostasis and inflammation, influencing normal brain function as well as contributing to neurological disorders. <h3>Aims</h3> Research on meningeal immune alterations in the context of HD is lacking, identifying a significant knowledge gap in its role in this neurodegenerative disease. Therefore, this study seeks to increase understanding of the role of meningeal immunity in HD pathology. <h3>Methods</h3> We utilized the R6/2 mouse model to analyze immune cell populations in both R6/2 and wildtype mice meninges using flow cytometry. Male and female mice at a time point reflecting late stage disease progression were selected for this study. <h3>Results</h3> In the meningeal immune cell population of both R6/2 and wildtype mice, we found that R6/2 mice displayed a significant elevation in the percentage of Tregs compared to wildtype. This was not accompanied by differences in the frequency of T cells. Analysis of T cell subpopulations revealed similar percentages of Th1 cells for both genotypes. Additionally, our current experiments encompass the analysis of B cells, macrophages, and dendritic cells. <h3>Conclusions</h3> In conclusion, our study presents initial evidence of alterations in meningeal immune cells within an HD mouse model, emphasizing the necessity for further exploration of the meningeal immune system’s role in HD.