Thesis Loreto Parga Vidal

Summary

Our immune system has evolved over the years to endow us with optimal protection against a wide range of invading pathogens on a daily basis. Immunological memory is a key factor in the success of the immune system and it relies on the complementary action of memory CD8+ T cells, memory CD4+ T cells and B cells. Three memory CD8+ T cell subsets have been defined based on their trafficking properties and specific functions: central memory (TCM), effector memory (TEM) and tissue-resident memory (TRM) T cells. In contrast to TCM and TEM, TRM do not recirculate and they permanently reside in peripheral tissues where they act as sentinels that can quickly engage effector functions upon local reinfection. Importantly, multiple studies have shown the superior capacity of TRM to provide local protection against pathogens and tumors.
Given their importance in protection against reinfection, unraveling the specific features of TRM appears highly relevant to improve T cell-targeted immunotherapeutic approaches. To develop TRM for therapy, it is essential to understand how TRM arise within the T cell population after primary infection and how they respond upon pathogen re-encounter to clear the secondary infection. Thus, in this thesis, we aimed to elucidate the mechanisms governing TRM biology: from early development upon pathogen encounter, to their interaction with the microenvironment during maintenance, and to their reactivation during secondary responses. Our findings provide a solid framework of the cellular and molecular mechanisms underlying the journey of a TRM during infection.