P060 The pharmacologic inhibition of store-operated calcium entry pathway in inflammatory bowel disease

Abstract

Abstract Background Store-operated calcium entry (SOCE) represents the major calcium influx pathway in T cells which not only controls the activation and function of lymphocytes, but which also has been implicated in the metabolic homeostasis and survival of murine CD4+ and CD8+ T cells. Conditional knockout mice, in which SOCE signalling components are deleted in T cells, revealed that SOCE is required for the induction of intestinal inflammation in mouse models of colitis. However, the effects of SOCE inhibition have not been studied in inflammatory bowel disease (IBD) and it remains elusive, which immune cell subset is affected by the pharmaceutical blockade of SOCE. We therefore aim to investigate the effects of SOCE inhibitor BTP-2 on functions and metabolic homeostasis of human lymphocytes isolated from IBD patients. Methods PBMC and/or lamina propria lymphocytes were isolated from colitis patients undergoing colon resection and mass cytometry served in order to evaluate the cytokine production and activation of B, T, NK as well as myeloid cells. Additionally, Ca2+ influx measurement and Seahorse analyses were performed in order to assess the metabolic status of immune cell subsets after SOCE inhibition. Results Data on B, T, NK, myeloid cells and neutrophils isolated from peripheral blood or colon lamina propria revealed that each immune cell subset harbours a distinctive SOCE-dependent Ca2+ influx rate, suggesting that SOCE might differentially regulate the activation and function of each cell subtype. In particular, CD4+ and CD8+ T cells, B and NK cells as well as monocytes were highly susceptible to extracellular Ca2+ influx, followed by granulocytes. Furthermore, inhibition of SOCE in lymphocytes resulted in impaired metabolic fitness, reduced glycolytic capacity and impaired fatty acid oxidation. Finally, BTP-2 was able to decrease the production of key pro-inflammatory cytokines involved in IBD, including TNFα and IL-17 in lamina propria resident T cells. Conclusion Our data revealed for the first time that the cytokine production and the activation of several immune cell subtypes can be modulated by SOCE blockade in human intestinal inflammation, identifying SOCE as a novel therapeutic target in colitis. Moreover, we hope that a wide phenotypical characterisation of immune cells via mass cytometry will provide a better insight into positive as well as negative effects of SOCE inhibitors that might interfere with the clinical applicability of SOCE inhibitors for treating IBD.