The Toxoplasma gondii ME-49 strain upregulates levels of A20 that inhibit NF-κB activation and promotes apoptosis in human leukaemia T-cell lines

Background: Acute T-lymphocyte leukaemia is a form of haematological malignancy with abnormal activation of NF-κB pathway, which results in high expression of A20 and ABIN1, which constitute a negative feedback mechanism for the regulation of NF-κB activation. Clinical studies have found that acute T-lymphocyte leukaemia patients are susceptible to Toxoplasma gondii infection; however, the effect of T. gondii on the proliferation and Apoptosis of human leukaemia T-cells remains unclear. Here, we used the T. gondii ME-49 strain to infect human leukaemia T-cell lines Jurkat and Molt-4, to explore the effect of T. gondii on proliferation and Apoptosis, which is mediated by NF-κB in human leukaemia T-cells.

Methods: The Tunel assay was used to detect cell Apoptosis. Cell Counting Kit-8 was used to detect cell proliferation viability. The Apoptosis level and the expression level of NF-κB related proteins in human leukaemia T-cells were detected by flow cytometry and Western blotting.

Results: Western blotting analyses revealed that the T. gondii ME-49 strain increased the expression of A20 and decreased both ABIN1 expression and NF-κB p65 phosphorylation. By constructing a lentiviral-mediated shRNA to knockdown the A20 gene in Jurkat T-cells and Molt-4 T-cells, the Apoptosis levels of the two cell lines decreased after T. gondii ME-49 Infection, and levels of NF-κB p65 phosphorylation and ABIN1 were higher than in the non-konckdown group. After knockingdown ABIN1 gene expression by constructing the lentiviral-mediated shRNA and transfecting the recombinant expression plasmid containing the ABIN1 gene into two cell lines, Apoptosis levels and cleaved Caspase-8 expression increased or decreased in response to T. gondii ME-49 Infection, respectively.

Conclusions: Our data suggest that ABIN1 protects human leukaemia T-cells by allowing them to resist the Apoptosis induced by T. gondii ME-49 and that the T. gondii ME-49 strain induces the Apoptosis of human leukaemia T-cells via A20-mediated downregulation of ABIN1 expression.