Figure 1.

Immune signaling in the colon carcinoma cell line, Caco-2, co-incubated with Giardia intestinalis GS isolate (0–10h). The activation of the immune signaling is mediated by the transcription factors, nuclear factor kappa-B (NFκB) and activator protein-1 (AP-1) and phosphorylated mitogen activated protein kinases (MAPKs), ERK1/2 and P38. (A) Western blot analysis of NFκB translocation into the nucleus of parasitized differentiated Caco-2 cells. The blots also show the phosphorylation of ERK1/2 (3–10 h) and P38 (1.5 h) in co-incubations with GS trophozoites. (B) Immunofluorescent staining of NFκB translocation into the nucleus of parasitized differentiated Caco-2 cells (See fluorescent green dots in the nucleus). Positive control in immunofluorescent images is differentiated Caco-2 cell incubated with 100 ng of tumor necrosis factor alpha per ml of culture medium. Negative control in differentiated Caco-2 cells incubated alone in culture medium. (C) Western blot analysis showing the nuclear translocation of NFκB and the activation of AP-1 as assessed by a luciferase reporter system transfected into proliferating Caco-2 cells. Western blots also show a slight increase in Erk1/2 phosphorylation at 1.5 h in proliferating Caco-2 cells co-incubated with GS trophozoites (0–10 h). TATA box binding protein (TBP) is the nuclear loading control used in Western blots. P-Erk is the phosphorylated form of Erk and P-P38 is the phosphorylated form of P38. ^*P < 0.05, ^**P < 0.01, and ^****P < 0.001.