PD-1 and ICOS counter-regulate tissue resident regulatory T cell development and IL-10 production during flu
Regulatory T cells that express the transcription factor Foxp3 (Treg cells) are a highly heterogenous population of immunoregulatory cells critical for maintaining immune homeostasis and preventing immunopathology during infections. Tissue resident Treg (TR-Treg) cells are maintained within nonlymphoid tissues and have been shown to suppress proinflammatory tissue resident T cell responses and promote tissue repair. Human populations are repetitively exposed to influenza infections and lung tissue resident effector T cell responses are associated with flu-induced long-term pulmonary sequelae. The kinetics of TR-Treg cell development and molecular features of TR-Treg cells during repeated and/or long-term flu infections are unclear. Utilizing a Foxp3/IL-10 dual reporter mouse model along with intravascular fluorescent labeling, we characterized the TR-Treg cell responses to repetitive heterosubtypic influenza infections. We found lung tissue resident Treg cells accumulated and expressed high levels of co-inhibitory and co-stimulatory receptors post primary and secondary infections. Blockade of PD-1 or ICOS signaling reveals that PD-1 and ICOS signaling pathways counter-regulate TR-Treg cell expansion and IL-10 production, during secondary influenza infection. Furthermore, the virus-specific TR-Treg cell response displayed distinct kinetics, when compared to conventional CD4 tissue resident memory T cells, during secondary flu infection. Our results provide insight into the tissue resident Foxp3 regulatory T cell response during repetitive flu infections, which may be applicable to other respiratory infectious diseases such as tuberculosis and COVID.
Publication Source (Journal or Book title)
Frontiers in immunology
McGee, M. C., Zhang, T., Magazine, N., Islam, R., Carossino, M., & Huang, W. (2022). PD-1 and ICOS counter-regulate tissue resident regulatory T cell development and IL-10 production during flu. Frontiers in immunology, 13, 984476. https://doi.org/10.3389/fimmu.2022.984476