Regenerating murine CD8+ lung tissue resident memory T cells after targeted radiation exposure

The type I IFN-IL-27 axis promotes mRNA vaccine-induced CD8 + T cell responses

The ability of lipid nanoparticle (LNP)-delivered mRNA vaccines to induce type I IFNs is critical to promote CD8 + T cell responses. The studies presented here indicate that immunization with nucleoside modified mRNA-LNP vaccines drives myeloid cell expression of the cytokine IL-27, which acts on antigen-specific CD8 + T cells to sustain T cell expansion. In vitro and in vivo studies revealed that type I IFN signaling is necessary for mRNA-LNP-induced IL-27 production, that immunization failed in IL-27 KO mice, and that immunization of IFNAR1-deficient mice with mRNA-LNP particles that also encode IL-27 mRNA restored antigen-specific CD8 + T cell responses. In addition, IL-27 mRNA-LNPs served as an adjuvant that improved cytolytic CD8 + T cell responses and the therapeutic efficacy of mRNA-LNPs to drive anti-pathogen and anti-tumor immunity. These studies highlight the central role of IL-27 in mRNA-LNP induced CD8 + T cell responses and the ability of this cytokine to augment the functionality of the CD8 + T cell response for prophylactic or therapeutic immunization.

Tissue-resident memory T cells in diseases and therapeutic strategies

Tissue-resident memory T (TRM) cells are crucial components of the immune system that provide rapid, localized responses to recurrent pathogens at mucosal and epithelial barriers. Unlike circulating memory T cells, TRM cells are located within peripheral tissues, and they play vital roles in antiviral, antibacterial, and antitumor immunity. Their unique retention and activation mechanisms, including interactions with local epithelial cells and the expression of adhesion molecules, enable their persistence and immediate functionality in diverse tissues. Recent advances have revealed their important roles in chronic inflammation, autoimmunity, and cancer, illuminating both their protective and their pathogenic potential. This review synthesizes current knowledge on TRM cells' molecular signatures, maintenance pathways, and functional dynamics across different tissues. We also explore the interactions of TRM cells with other immune cells, such as B cells, macrophages, and dendritic cells, highlighting the complex network that underpins the efficacy of TRM cells in immune surveillance and response. Understanding the nuanced regulation of TRM cells is essential for developing targeted therapeutic strategies, including vaccines and immunotherapies, to enhance their protective roles while mitigating adverse effects. Insights into TRM cells' biology hold promise for innovative treatments for infectious diseases, cancer, and autoimmune conditions.

Joint-specific memory, resident memory T cells and the rolling window of opportunity in arthritis

In rheumatoid arthritis, juvenile idiopathic arthritis and other forms of inflammatory arthritis, the immune system targets certain joints but not others. The pattern of joints affected varies by disease and by individual, with flares most commonly involving joints that were previously inflamed. This phenomenon, termed joint-specific memory, is difficult to explain by systemic immunity alone. Mechanisms of joint-specific memory include the involvement of synovial resident memory T cells that remain in the joint during remission and initiate localized disease recurrence. In addition, arthritis-induced durable changes in synovial fibroblasts and macrophages can amplify inflammation in a site-specific manner. Together with ongoing systemic processes that promote extension of arthritis to new joints, these local factors set the stage for a stepwise progression in disease severity, a paradigm for arthritis chronicity that we term the joint accumulation model. Although durable drug-free remission through early treatment remains elusive for most forms of arthritis, the joint accumulation paradigm defines new therapeutic targets, emphasizes the importance of sustained treatment to prevent disease extension to new joints, and identifies a rolling window of opportunity for altering the natural history of arthritis that extends well beyond the initiation phase of disease.