PhD student National Institute of Medical Sciences and Nutrition (INCMNSZ) Mexico City, Mexico
Disclosure(s):
Adrian Albarran-Godinez, Bsc in Biomedical Research: No financial relationships to disclose
Introduction/Rationale: CD4 T cells specific to dietary antigens are inactivated through mechanisms that include deletion, anergy, and acquisition of regulatory capacities. The factors that guide the fate of these cells are unknown. Here, we analyzed the role of antigen-associated factors (e.g., concentration, frequency, affinity) in determining CD4 T cell fate during oral tolerance.
Methods: We adoptively transferred naïve OTII CD4 T cells and fed mice with different regimes of the model antigen ovalbumin (OVA). A single dose of OVA induced an early but short-lived induction of FoxP3. Gradually, FoxP3+ cells decreased and anergic cells became the dominant population. Fate mapping analyses revealed that regulatory and anergic programs are mostly exclusive. Ultimately, the majority of OTII cells became apoptotic.
Results: Repetitive administration of OVA was associated with a higher expression of anergy-associated molecules (e.g., Ctla-4, Nrp-1) and transcription factors (e.g., TOX, Helios) in a dose-dependent manner, suggesting that repetitive exposure to cognate antigen gradually induces a more profound CD4 T cell inactivation. Additionally, repetitive exposure to OVA promoted homing of anergic CD4 T cells into the lamina propria. However, tolerance was a short-lived process, as its effect was not detected after OVA was discontinued. Using OVA-specific tetramers, we identified high and low affinity CD4 T cells and explored the transcriptomic changes induced by oral antigen (scRNA-seq). In vitro examination of tolerogenic fates using ligands of different affinities showed that weak TCR activation was associated with the development of anergy.
Conclusion: Collectively, our results indicate that tolerance to oral antigens represents a gradual and dynamic process, controlled by the intensity of antigenic stimulation, where expression of FoxP3 and anergy-associated markers represent a transient phase that leads to clonal deletion.
