Imunoglobulina a (IgA) do colostro humano adsorvida a microesfera de polietilenoglicol para ação em células tumorais de mama moduladas pela presença do fator de crescimento epidermal

Abstract

The adsorption of biomolecules, such as hormones and proteins, to polyethylene glycol microspheres (PEG), presents immunomodulatory capacity and suggest that the adsorption of these compounds to PEG microspheres has immunostimulatory effects and can be considered an important material for the development of modified release systems (SLM) with potential for future therapeutic applications in infectious diseases or tumors. This combination has numerous advantages such as prolonged permanence in the body and decreased degradation by metabolic enzymes. The aim of this study was to evaluate the influence of epidermal growth factor (EGF) on the effects of SIgA (Immunoglobulin A Secretory) adsorbed to PEG microsphere in blood mononuclear cells (MN) and breast cancer tumor cell lines (MCF-7). Twenty colostrum samples from healthy postpartum women were collected for the purification of IgA and 10 blood samples from healthy donors to evaluate the anti-tumor activity of these cells and in co-culture of breast tumor cells and mononuclear blood cells. In colostrum samples, the concentration of SIgA and EGF were quantified by the ELISA method and SIgA obtained by affinity chromatography. Mononuclear cells (MN) were obtained from blood samples. PEG microspheres were produced and analyzed by fluorescence microscopy. The release curve of PEG adsorbed SIgA in culture supernatant was determined by ELISA. Cell viability was assessed by the MTT method. The oxidative metabolism of cells was evaluated by releasing Superoxide Anion (O2 - ) and Superoxide Dismutase (Cu-Zn-SOD). In breast milk, 417.8 ± 51.34 mg/mL of SIgA and 1.09 ± 0.38 ng/mL of EGF were found. From the purification of SIgA from colostrum supernatant 3 eluates were obtained, two at 32 mg/dL and one at 64 mg/dL. PEG microspheres analysis showed stable spherical structures capable of adsorbing SIgA and presented a satisfactory SIgA release profile in terms of concentration and time. It was observed that blood MN cells incubated with IgA adsorbed or not to the PEG in the presence of EGF presented reduced (p <0.05) viability, whereas in the absence of EGF cells incubated with IgA, PEG and PEG-IgA showed no differences when compared to the control (p> 0.05), suggesting that IgA adsorbed or not to the PEG microspheres did not present cell toxicity. In MCF-7 cells viability was reduced to 86% in the presence of IgA and 47% in the presence of IgA adsorbed to the PEG microsphere. EGF increased the viability (72%) of MCF-7 cells incubated with PEG-IgA. There were no differences in cell coculture. Regarding oxidative metabolism, phagocytes showed increased release of O2 -when incubated with IgA adsorbed or not to the PEG microsphere in the presence and absence of EGF when compared to spontaneous release. There was also an increase in SOD production in MN blood cell culture supernatant incubated by immunomodulators. For MCF-7 cells there was an increase of O2 - when cells were incubated with PEG-IgA. In the presence of EGF and PEG it was observed that MCF-7 cells reduced SOD activity. When evaluating MN and MCF-7 cell culture, no significant difference was observed for superoxide anion release. EGF reduced the concentration of SOD in the supernatant of cells incubated with PEG and PEG-IgA. These data suggest that epidermal growth factor may interfere with the antitumor action of SIgA adsorbed on PEG microsphere.