ß2 Integrins differentially regulate γδ T cell subset thymic development and peripheral maintenance.

The γδ T cells reside predominantly at barrier sites and play essential roles in immune protection against infection and cancer. Despite recent advances in the development of γδ T cell immunotherapy, our understanding of the basic biology of these cells, including how their numbers are regulated in vivo, remains poor. This is particularly true for tissue-resident γδ T cells. We have identified the ß2 family of integrins as regulators of γδ T cells. ß2-integrin-deficient mice displayed a striking increase in numbers of IL-17-producing Vγ6Vδ1+ γδ T cells in the lungs, uterus, and circulation. Thymic development of this population was normal. However, single-cell RNA sequencing revealed the enrichment of genes associated with T cell survival and proliferation specifically in ß2-integrin-deficient IL-17+ cells compared to their wild-type counterparts. Indeed, ß2-integrin-deficient Vγ6+ cells from the lungs showed reduced apoptosis ex vivo, suggesting that increased survival contributes to the accumulation of these cells in ß2-integrin-deficient tissues. Furthermore, our data revealed an unexpected role for ß2 integrins in promoting the thymic development of the IFNγ-producing CD27+ Vγ4+ γδ T cell subset. Together, our data reveal that ß2 integrins are important regulators of γδ T cell homeostasis, inhibiting the survival of IL-17-producing Vγ6Vδ1+ cells and promoting the thymic development of the IFNγ-producing Vγ4+ subset. Our study introduces unprecedented mechanisms of control for γδ T cell subsets.

Visualising the interaction of CD4 T cells and DCs in the evolution of inflammatory arthritis.

OBJECTIVES: Successful early intervention in rheumatoid arthritis (RA) with the aim of resetting immunological tolerance requires a clearer understanding of how specificity, cellular kinetics and spatial behaviour shape the evolution of articular T cell responses. We aimed to define initial seeding of articular CD4+ T cell responses in early experimental arthritis, evaluating their dynamic behaviour and interactions with dendritic cells (DCs) in the inflamed articular environment. METHODS: Antigen-induced arthritis was used to model articular inflammation. Flow cytometry and PCR of T cell receptor (TCR) diversity genes allowed phenotypic analysis of infiltrating T cells. The dynamic interactions of T cells with joint residing DCs were visualised using intravital multiphoton microscopy. RESULTS: Initial recruitment of antigen-specific T cells into the joint was paralleled by accumulation of CD4+ T cells with diverse antigen-receptor expression and ability to produce tumour necrosis factor alpha (TNFα) and interferon gamma (IFNγ) on mitogenic restimulation. A proportion of this infiltrate demonstrated slower motility speeds and engaged for longer periods with articular DCs in vivo. Abatacept treatment did not disrupt these interactions but did reduce T cell expression of inducible costimulatory (ICOS) molecule. We also demonstrated that non-specific CD4+ T cells could be recruited during these early articular events. CONCLUSIONS: We demonstrate that CD4+ T cells engage with articular DCs supporting antigen specific T cell reactivation. This cellular dialogue can be targeted therapeutically to reduce local T cell activation.

Diet, nutrient supply, and tumor immune responses.

Nutrients are essential for cell function. Immune cells operating in the complex tumor microenvironment (TME), which has a unique nutrient composition, face challenges of adapting their metabolism to support effector functions. We discuss the impact of nutrient availability on immune function in the tumor, competition between immune cells and tumor cells for nutrients, and how this is altered by diet. Understanding which diets can promote antitumor immune responses could open a new era of treatment, where dietary modifications can be used as an adjunct to boost the success of existing cancer therapies.

γδ T cell dichotomy with opposing cytotoxic and wound healing functions in human solid tumors.

γδ T cells are important tissue-resident, innate T cells that are critical for tissue homeostasis. γδ cells are associated with positive prognosis in most tumors; however, little is known about their heterogeneity in human cancers. Here, we phenotyped innate and adaptive cells in human colorectal (CRC) and endometrial cancer. We found striking differences in γδ subsets and function in tumors compared to normal tissue, and in the γδ subsets present in tumor types. In CRC, an amphiregulin (AREG)-producing subset emerges, while endometrial cancer is infiltrated by cytotoxic cells. In humanized CRC models, tumors induced this AREG phenotype in Vδ1 cells after adoptive transfer. To exploit the beneficial roles of γδ cells for cell therapy, we developed an expansion method that enhanced cytotoxic function and boosted metabolic flexibility, while eliminating AREG production, achieving greater tumor infiltration and tumor clearance. This method has broad applications in cellular therapy as an 'off-the-shelf' treatment option.