Abstract
Background:
Resident immune cells are central in shaping the lung's tissue-specific immunity. Precision-cut lung slices (PCLS) preserve the native tissue microenvironment and are therefore an excellent ex vivo model to analyze residency and functionality of resident memory T cells.
Methods:
To study the modulation of tissue residency markers and T cell activation in the native lung niche, we treated PCLS with broad and T cell-specific stimuli and analyzed responses using flow cytometry and mediator secretion analysis. Using TGFβ, anti-CD3/CD28, IL-2 and a pool of MHC-I restricted peptides we analyzed cytokine secretion, CD4+/CD8+ T cell ratios, and the expression of activation and residency markers.
Results:
First, we characterized lung immune cell in PCLS which also revealed that resident memory T cells are abundant in PCLS. We showed that regulation of the tissue residency marker CD103 is dependent on TGFβ or IL-2 signaling in combination with T cell receptor engagement. Further, polyclonal activation of T cells in the tissue reduced tissue secretion of anti-inflammatory cytokines like TGFβ, while increasing the secretion of T cell-associated cytokines like IFNγ, IL-2, and Granzyme B. This shift was supported by an upregulation of T cell activation markers such as CD39, CD137, and Ki-67. Finally, treatment of PCLS with a pool of MHC-I-restricted peptides led to increased secretion of multiple inflammatory effector cytokines associated and a specific activation of tissue resident T cells.
Conclusion:
Taken together, we have demonstrated that PCLS provide an excellent platform to modulate tissue resident T cell responses influenced by human lung tissue microenvironment.