The interplay between serine proteases and caspase-1 regulates the autophagy-mediated secretion of Interleukin-1 beta in human neutrophils

Neutrophils play major roles against bacteria and fungi infections not only due to their microbicide properties but also because they release mediators like Interleukin-1 beta (IL-1β) that contribute to orchestrate the inflammatory response. This cytokine is a leaderless protein synthesized in the cytoplasm as a precursor (pro-IL-1β) that is proteolytically processed to its active isoform and released from human neutrophils by secretory autophagy. In most myeloid cells, pro-IL-1β is processed by caspase-1 upon inflammasome activation. Here we employed neutrophils from both healthy donors and patients with a gain-of-function (GOF) NLRP3-mutation to dissect IL-1β processing in these cells. We found that although caspase-1 is required for IL-1β secretion, it undergoes rapid inactivation, and instead, neutrophil serine proteases play a key role in pro-IL-1β processing. Our findings bring to light distinctive features of the regulation of caspase-1 activity in human neutrophils and reveal new molecular mechanisms that control human neutrophil IL-1β secretion.

Glioblastoma cells potentiate the induction of the Th1-like profile in phosphoantigen-stimulated γδ T lymphocytes

PURPOSE

γδ T lymphocytes are non-conventional T cells that participate in protective immunity and tumor surveillance. In healthy humans, the main subset of circulating γδ T cells express the TCRVγ9Vδ2. This subset responds to non-peptide prenyl-pyrophosphate antigens such as (E)-4-hydroxy-3-methyl-but-enyl pyrophosphate (HMBPP). This unique feature of Vγ9Vδ2 T cells makes them a candidate for anti-tumor immunotherapy. In this study, we investigated the response of HMBPP-activated Vγ9Vδ2 T lymphocytes to glioblastoma multiforme (GBM) cells.

METHODS

Human purified γδ T cells were stimulated with HMBPP (1 µM) and incubated with GBM cells (U251, U373 and primary GBM cultures) or their conditioned medium. After overnight incubation, expression of CD69 and perforin was evaluated by flow cytometry and cytokines production by ELISA. As well, we performed a meta-analysis of transcriptomic data obtained from The Cancer Genome Atlas.

RESULTS

HMBPP-stimulated γδ T cells cultured with GBM or its conditioned medium increased CD69, intracellular perforin, IFN-γ, and TNF-α production. A meta-analysis of transcriptomic data showed that GBM patients display better overall survival when mRNA TRGV9, the Vγ9 chain-encoding gene, was expressed in high levels. Moreover, its expression was higher in low-grade GBM compared to GBM. Interestingly, there was an association between γδ T cell infiltrates and TNF-α expression in the tumor microenvironment.

CONCLUSION

GBM cells enhanced Th1-like profile differentiation in phosphoantigen-stimulated γδ T cells. Our results reinforce data that have demonstrated the implication of Vγ9Vδ2 T cells in the control of GBM, and this knowledge is fundamental to the development of immunotherapeutic protocols to treat GBM based on γδ T cells.

Good outcome of children with acute myeloid leukemia and t(8;21)(q22;q22), even when associated with granulocytic sarcoma: a report from a single institution in Argentina

BACKGROUND

The association between t(8;21) and granulocytic sarcoma (GS) is well known, but to the authors' knowledge the prognostic significance of GS in these patients has not been defined clearly.

METHODS

Between January 1990 and July 1999 174 children with acute myeloid leukemia were admitted to the study institution. Translocation (8;21) was identified in 20 patients (11.5%). Eighteen patients were evaluable for the current study and 8 presented with GS at the time of diagnosis (GS+).

RESULTS

The authors defined two groups of patients: those who were GS+ and those who were GS-. One patient in the GS+ group and two patients in the GS- group died during the induction phase of the study. Complete remission was achieved in seven patients in the GS+ group and eight patients in the GS- group. Two patients developed a recurrence in the GS+ group as did one patient in the GS- group. The event free-survival probability (the standard error) was 58% (18%) in the GS+ group and 70% (14%) in the GS- group. Localization of GS was in only one site in seven patients and at multiple sites in one patient. Patients with an epidural mass received local radiotherapy (one patient) or surgery (two patients). Two of these patients developed paraplegia as sequelae: one patient after surgery and one patient after radiotherapy. One patient with orbital GS received local radiotherapy because of progressive proptosis. The remaining four patients had a complete resolution of the GS with chemotherapy only.

CONCLUSIONS

In the current study of patients with t(8;21)(q22;q22), the presence of granulocytic sarcoma was not found to be an adverse prognostic factor. However, careful attention should be paid, especially to patients with an epidural site, to avoid sequelae. Chemotherapy appears to be the optimum treatment for these children.