The inducible costimulator (ICOS) plays a key role in CD4+ Th17 cell development, but its role in CD8+ Tc17 cell development and self/tumor immunity remains unknown. We found that ICOS co-stimulation was important for the functional maintenance but not differentiation of Tc17 cells in vitro. Blocking the ICOS pathway using an antagonist antibody or by using mice genetically deficient in the ICOS ligand (ICOSL) reduced the antitumor activity of adoptively transferred Tc17 cells. Conversely, activating Tc17 cells with an ICOS agonist in vitro enhanced their capacity to eradicate melanoma and induce autoimmune vitiligo when infused into mice. However, ICOS stimulation did not augment the antitumor activity of IL-2 expanded T cells. Additional investigation revealed that ICOS stimulation not only increased IL-2Rα, CXCR3 and IL-23R expression on Tc17 cells, but also dampened their expression of suppressive molecule CD39. Although Tc17 cells activated with an ICOS agonist co-secreted heightened IL-17A, IL-9 and IFN-γ, their therapeutic effectiveness was critically dependent on IFN-γ production. Depletion of IL-17A and IL-9 had little impact of antitumor Tc17 cells activated with an ICOS agonist. Collectively, our work reveals that the ICOS pathway potentiates the antitumor activity of adoptively transferred Tc17 cells. This work has major implications for the design of vaccine, antibody and cell-based therapies for autoimmunity, infectious disease and cancer.

Purpose The adoptive cell transfer (ACT) of CD8+ T cells is a promising treatment for advanced malignancies. Lymphodepletion prior to ACT enhances IFN-γ+CD8+ T cell (Tc0) mediated tumor regression. Yet, how lymphodepletion regulates the function and antitumor activity of IL-17A+CD8+ T cells (Tc17) is unknown. Experimental Design To address this question, pmel-1 CD8+ T cells were polarized to secrete either IL-17A or IFN-γ. These subsets were then infused into mice with B16F10 melanoma that were lymphoreplete (no TBI), or lymphodepleted with non-myeloablative (5 Gy) or myeloablative (9 Gy requiring hematopoietic stem cell transplantation) TBI. The activation of innate immune cells and function of donor T cell subsets was monitored in these preconditioned mice. Results Tc17 cells regress melanoma in myeloablated mice to a greater extent than in lymphoreplete or non-myeloablated mice. TBI induced functional plasticity in Tc17 cells causing conversion from IL-17A to IFN-γ producers. Additional investigation revealed that Tc17 plasticity and antitumor activity was mediated by IL-12 secreted by irradiated host dendritic cells. Neutralization of endogenous IL-12 reduced the antitumor activity of Tc17 cells in myeloablated mice, while ex vivo priming with IL-12 enhanced their capacity to regress melanoma in non-myeloablated animals. This, coupled with exogenous administration of low dose IL-12, obviated the need for host preconditioning creating curative responses in non-irradiated mice, Conclusions Our findings indicate that TBI-induced IL-12 augments Tc17 cell-mediated tumor immunity and underline the substantial implications of in vitro preparation of antitumor Tc17 cells with IL-12 in the design of T cell immunotherapies.

Objective The aim of this study was to determine the effects of acetaldehyde on various steps of the monocyte recruitment cascade. Methods Human umbilical venous endothelial cells (HUVEC), primary blood monocytes (PBM) and THP-1 monocytes, were treated with acetaldehyde (0.1–0 μM) for 6 h. Monocyte adherence experiments were performed using 2′,7′-bis(2-carboxyethyl)-5,6-carboxyfluorescein-acetoxymethylester labeled PBM or 3H-thymidine labeled THP-1 cells. HUVEC TNFα mRNA and protein levels were determined by quantitative real-time PCR and immunoassay, respectively, and HUVEC P-selectin and monocyte CCR2 expression were determined by FACS analysis. Results Acetaldehyde dose-dependently increased the number of CCR2 positive THP-1 monocytes, with a maximal increase of ~50% observed in the presence of 10 μM acetaldehyde. There was a significant increase in both the number of P-selectin positive cells and P-selectin receptor density when HUVEC were incubated with acetaldehyde. HUVEC TNFα mRNA expression and secretion were enhanced by acetaldehyde. Moreover, acetaldehyde increased THP-1 and PBM adhesion to HUVEC. Inhibition of P-selectin or TNFα, using antibodies or siRNA-directed gene knockdown, attenuated acetaldehyde-induced monocyte adhesion. In conclusion, acetaldehyde increased the number of CCR2 positive monocytes and stimulated endothelial cell P-selectin and TNFα expression. Moreover, acetaldehyde increased monocyte adhesion to endothelial cells, an effect that was both P-selectin- and TNFα-dependent. Conclusion These effects of acetaldehyde may contribute, in part, to the increase in coronary heart disease that is associated with binge patterns of alcohol consumption.