IL-4/STAT-6/SOCS-5 axis in the differentiation of dendritic cells: effects of melatonin.

Author(s)

Aline Arruda de Oliveira

• Document type: Master's Dissertation
• Press: São Paulo.
• Institution: Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI)
• Defense date: 2017-09-22

Examining board members

Jose Alexandre Marzagao Barbuto; Cristina de Oliveira Massoco Salles Gomes; Fábio Martins Laginha; Telma Miyuki Oshiro Sumida

• Advisor: Jose Alexandre Marzagao Barbuto

Abstract

Previous studies at our lab have shown that melatonin (MLT) acts on monocytes increasing their sensitivity to Interleukin-4 (IL-4) and, consequently, generating dendritic cells (DCs) when in vitro and treated with IL-4 and GM-CSF (mo-DCs) phenotically and functionally more activated. Other studies from our group have shown that mo-DCs obtained from cancer patients have functional biases capable of compromising the activation of T lymphocytes. Another result from our group pointed to the fact that part of the mo-DCs\' functional bias in cancer patients could be attributed to the decrease in STAT-6 signaling, a pathway that is activated by IL-4 and down regulated by SOCS-5, whose levels, in turn, were found elevated in cancer patients\' monocytes. Based on these results, the present work aimed to investigate the effects of MLT on the in vitro differentiation of healthy donors and breast cancer patients mo-DCs, under the hypothesis that this hormone could act on the IL-4/STAT-6/SOCS-5 axis generating better activated mo-DCs. Peripheral blood monocytes from healthy donors and breast cancer patients were treated with MLT (2,5 nM 2 hours) and induced to differentiate into mo-DCs; on the fifth day cells were activated with LPS (100 ng/ml 24 hours). Flow cytometry analysis of phenotype and cytokines in supernatants during mo-DCs differentiation didnt show MLT effects, but indicated higher frequency of CD83+ (p=0,014) monocytes among mononuclear cells of the patients, when compared with healthy donors. In addition, higher concentration of IL-12p70 was found in mo-DCs cultures (sixth day - p=0,02). The capacity to stimulate allogeneic T lymphocytes was assessed by co-cultures (1DC : 30LT), maintained for 5 days. Results indicate an effect of MLT only in order to increase the TNF, IFN-γ and IL-2 concentrations in supernatants of co-cultures with healthy donors mo-DCs. Patients cells showed differences only when there was no hormone treatment, showing higher levels of IL-10 in the co-culture supernatants, when compared to healthy controls. Monocytes were also treated with MLT (2,5 nM) or IL-4 (50 ng/mL) for 15 minutes to evaluate STAT-6, pSTAT-6 and SOCS-5 expression. Results showed an increase of STAT-6 in patients monocytes and a lower capacity of these cells to phosphorylate this molecule, even when in presence of IL-4. Together, the results point to some phenotypic and functional differences between patients and healthy donors monocytes, but it was not shown in their mo-DCs. Results also point to the fact that MLT generates changes only in healthy donors cells and those effects were only seen with cytokines found in cultures supernatants. (AU)

• FAPESP's process: 15/03314-1 - Melatonin effect on the IL-4/STAT6/SOCS5 axis during the differentiation of dendritic cells from monocytes of healthy donors or cancer patients
• Grantee: Aline Arruda de Oliveira
• Support Opportunities: Scholarships in Brazil - Master