43-Immunomodulatory activity of Tityus serrulatusscorpion venom on human T lymphocytes

Andrea Casella-Martins¹, Lorena R Ayres¹², Sandra M Burin¹, Fabiana R Morais¹, Juliana C Pereira¹, Lucia H Faccioli¹, Suely V Sampaio¹, Eliane C Arantes³, Fabiola A Castro¹, Luciana S Pereira-Crott¹

1 Department of Clinical Analyses, Toxicology and Food Sciences, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Avenida do Café, s/n, Ribeirão Preto CEP 14040-903, SP, Brazil

2 Department of Pharmaceutical Sciences, Federal University of Espírito Santo, Vitória, ES, Brazil

3 Department of Physics and Chemistry, School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo (USP), Ribeirão Preto, SP, Brazil

Background

Tityus serrulatus scorpion venom (TsV) contains toxins that act on K ⁺ and Na ⁺ channels and account for the venom’s toxic effects. TsV can activate murine peritoneal macrophages, but its effects on human lymphocytes have been poorly investigated. Considering that lymphocytes may play an important role in envenomation, we assessed whether TsV affects the expression of phenotypic (CD3, CD4, and CD8) and activation (CD69, CD25, and HLA-DR) markers, cell proliferation, and cytokine production in peripheral blood mononuclear cells.

Methods

Cytotoxicity of TsV was evaluated via the MTT assay. Cell proliferation, expression of phenotypic and activation markers, and release of cytokines were assessed using flow cytometry, after treatment with non-cytotoxic concentrations of TsV. The combined use of carboxyfluorescein diacetate succinimidyl ester and monoclonal antibodies against phenotypic and activation markers enabled us to simultaneously assess cell proliferation extent and cell activation status, and to discriminate among cell subpopulations.

Results

TsV at concentrations of 25 to 100 μg/mL were not cytotoxic towards peripheral blood mononuclear cells. TsV did not induce significant changes in lymphocyte subpopulations or in the expression of activation markers on CD4 ⁺ and CD8 ⁺ T cells. TsV inhibited the phytohemagglutinin-stimulated lymphocyte proliferation, particularly in the CD8 ⁺CD25 ⁺ T lymphocyte subset. TsV alone, at 50 and 100 μg/mL, did not induce peripheral blood mononuclear cell proliferation, but elicited the production and release of IL-6, a proinflammatory cytokine that plays an important role in innate and adaptive immune responses.

Conclusions

TsV is a potential source of molecules with immunomodulatory action on human T lymphocytes.

Key words: Immunomodulation; Immunophenotyping; T lymphocyte; Cell proliferation; Cytokine; Tityus serrulatus venom

The present study was approved by the Human Research Ethics Committee at FCFRP-USP registered under number CEP/FCFRP 166.

Received: February 19, 2015; Revised: November 5, 2015; Accepted: November 11, 2015

ACM performed the experiments and data analysis. LRA, JCP and SMB collaborated in the experiments and contributed to the conception of this manuscript. FRM performed the flow cytometry assays and contributed to the data analysis. ACM, LRA, SMB, FAC and LSPC wrote and reviewed the manuscript. FAC, LSPC and SVS raised funds for the research. ECA, SVS and LHF contributed to the writing of the manuscript. ECA also supervised the collection and preparation of TsV. LSPC and FAC conceived and coordinated the study, contributed to the interpretation of data and critically discussed the manuscript. All authors read and approved the final manuscript.