Regulation of human gamma/delta T cell activation by neutrophils: mechanisms and translational implications

• Applicant: Professor Dr. Dietrich Kabelitz
• Subject Area: Immunology
• Term: from 2014 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 264241294

Vgamm9Vdelta2 (Vg9Vd2) T cells comprise the major subset of gamma/delta T cells in human peripheral blood. In contrast to conventional CD4+ and CD8+ T cells, Vg9Vd2 T cells do not recognize antigenic peptides but rather pyrophosphate molecules (phosphoantigens, pAg) derived from the microbial or eukaryotic biosynthesis of isoprenoids. The presentation of such pAg is independent of MHC class I or class II but requires the expression of the butyrophilin member 3A1 (BTN3A1/CD277). The endogenous production of pAg in tumor cells and monocytes can be drastically increased by aminobisphosphonates such as zoledronate (ZOL) which are in clinical use for the treatment of osteoporosis and bone metastasis in various types of cancer. ZOL-treated monocytes stimulate the selective activation and expansion of Vg9Vd2 T cells, and ZOL-treated tumor cells are much more efficiently killed by Vg9Vd2 T cells. Therefore, ZOL plus low-dose IL-2 has been used to treat cancer patients in an attempt to activate tunmor-reactive Vg9Vd2 T cells in vivo, though with limited success. We recently reported that neutrophils take up ZOL efficiently and subsequently strongly suppress Vg9Vd2 T cell activation in response to ZOL which might contribute to the observed anergy and numerical decline of Vg9Vd2 T cells in the course of ZOL therapy. We identified production of reactive oxygen species (ROS) as a contributing factor which, however, could not fully explain the inhibitory effect. In this project we plan to study in detail the regulatory impact of neutrophils on gd T cell activation at the cellular and molecular level. As a first step, we will compare purified neutrophils and monocytes with respect to their capacity to present pAg to Vg9Vd2 T cells (expression/regulation of important molecules such as BTN3A1/CD277 and farnesyl pyrophosphate synthase, endogenous production of pAg in response to ZOL stimulation). Furthermore, we will investigate ROS production, NADPH oxidase activity, cytoskeleton reorganization, and differential gene expression patterns in both control and ZOL-activated granulocytes and monocytes. Vg9Vd2 activation and suppressive/regulatory activiy of neutrophils will be also determined in the blood of cancer patients who are newly put on intravenous ZOL therapy. Importantly, we will also devise strategies to prevent or counteract the inhibitory activity of neutrophils. The longterm goal of our project is to improve gdT cell-based immunotherapeutic approaches by preventing the suppressive role of neutrophils

• DFG Programme: Research Grants