The SEB1741 Aptamer Is an Efficient Tool for Blocking CD4+ T Cell Activation Induced by Staphylococcal Enterotoxin B

Abstract

Staphylococcal enterotoxin B (SEB) is a protein produced by Staphylococcus aureus, which is toxic to humans. It is well known for its ability to stimulate the exacerbated activation of proinflammatory CD4+ T cells (Th1 profile), and in vitro studies have been conducted to understand its mechanism of action and its potential use as an immune therapy. However, the efficiency of the SEB1741 aptamer in blocking SEB has not been experimentally demonstrated. Methods: Enrichment CD4+ T cells were stimulated with SEB, and as a blocker, we used the SEB1741 aptamer, which was previously synthesised by an “in silico” analysis, showing high affinity and specificity to SEB. The efficiency of the SEB1741 aptamer in blocking CD4+ T cell activation was compared with that of an anti-SEB monoclonal antibody. Flow cytometry and Bio-Plex were used to evaluate the T-cell function. Results: In vitro, SEB induced the activation of CD4+ T cells and favoured a Th1 profile; however, the SEB1741 aptamer was highly efficient in decreasing the frequency of CD4+ T cells positive to ki-67 and CD69 cells, this means that proliferation and activation of CD4+ T cells was decreased. Moreover, the production of interleukin 2 (IL-2) and interferon-gamma (IFN-γ) was affected, suggesting that the Th1 profile is not present when the SEB1441 aptamer is used. Thus, the SEB1741 function was similar to that of anti-SEB. Conclusions: The SEB1741 aptamer is a valuable tool for blocking CD4+ T cell activation and the subsequent release of proinflammatory cytokines by SEB stimulation.

The 4-1BBζ costimulatory domain in chimeric antigen receptors enhances CD8+ T-cell functionality following T-cell receptor stimulation

“…Indeed, experiments using NF-ΚB and AP-1 reporter cell lines show that PMA/ionomycin lead to substantially greater expression of both NF-ΚB and AP-1 compared to either 4-1BB signalling or plate-bound anti-CD3 antibodies used as control [ 47 ]. While the reporter cell experiments did not compare PMA/ionomycin with SEB, in T-cell functional assays that do compare PMA/ionomycin with SEB, it is common for CD69 [ 48 ], as well as intracellular cytokines [ 49 – 51 ], to be higher with PMA/ionomycin compared to SEB. Therefore, it is conceivable that SEB, especially in the absence of any antigen-presenting cells, is a weaker activator of AP-1 and CD69, allowing any incremental effect of 4-1BB signalling on CD69 expression to be detectable with SEB but not with PMA/ionomycin.…”