Objectives: Imidazole propionate (IP) is an intestinal microbial metabolite derived from histidine. It has been shown to impair insulin signaling in various cell types and levels are increased in plasma of patients with type II diabetes. Insulin receptor signaling also plays a key role in T cell function. Therefore, the objective of the current study is to determine if IP effect insulin signaling and alters T cell activation and proliferation.
Methods: Human peripheral blood mononuclear cells (PBMCs) were isolated from whole blood collected from healthy males (n=5) and females (n=5). PBMCs were isolated and T cells stimulated with phorbol 12-myristate 13-acetate (PMA) and ionomycin in the presence of brefeldin for 6 hours with and without IP. Intracellular levels of Interferon (IFN)-γ was measured in CD4 and CD8 T cells. Additionally, carboxyfluorescein succinimidyl ester (CFSE) labeled PBMCs were also stimulated with anti-CD3/CD28 and IL-2 for 72 hours and proliferation of CD4 and CD8 T cells determined using flow cytometry.
Results: Stimulation of human PBMCs with PMA and Ionomycin resulted in 21.89±8.34 % IFN-γpositive CD4 T cells. IP did not alter the induction of IFN-γ with 22.04±7.72 % IFN-γpositive CD4 T cells. Stimulation resulted in 48.52±16.85 % IFN-γpositive CD8 T cells, with no change resulting from IP co-incubation (47.64±17.39%). Stimulation of human PBMCs with CD3/CD28/IL-2 for 72 hours resulted in a 43.84±13.62% CD4 T cells proliferation with no change induced by IP (43.65±13.35%), while 55.21±10.36% CD8 T cells proliferated with no change in the presence of IP (54.65±9.5%).
Conclusions: IP have been shown to alter insulin signaling in various cell types, however, results from this study demonstrates that the effect of insulin signaling on the activation and proliferation of CD4 and CD8 T cells is not altered by IP.
Funding Sources: University of Memphis. Indirect Cost Recovery Funds (Van der Merwe)
