THE INHIBITION OF MIF WAS COUNTER-REGULATED IN PLACENTAL EXPLANTS INFECTED BY T. gondii

Abstract

Macrophage Migration Inhibitory Factor (MIF) is a cytokine that was first described as a protein able to inhibit the random migration of macrophages. Nowadays, MIF has been associated with several others functions related to physiology pathology and control of infection by intracellular parasites. In this sense, some methodologies have been proposed to inhibit MIF as therapeutic strategy or to clarify the roles of MIF in physiology and parasitology. In the present study we aimed to investigate anti-MIF and ISO-1 strategies to inhibit MIF in human placenta and to evaluate how these inhibitors can affect MIF production and secretion, intracellular signaling, production of pro-inflammatory factors and control of T. gondii proliferation. To accomplish this goal, human placental were treated with ISO-1 and anti-MIF followed by T. gondii infection. Then, villi and supernatant were collected following the kinetic of 24, 48 and 72 hours. Untreated and treated and uninfected villi were used as control. Supernatants from cultured explants were used for quantification of cytokine secretion. Explants were processed for morphological analysis, immunohistochemistry, ELISA, parasite quantification and Western blotting assays. Our results demonstrated that MIF secretion by placenta was reduced during the first 24 hours of treatments. However, this secretion was completely restored at 48 and 72 hours. Also, MIF production was increased instead of being inhibited in all treatment times. Likewise, MIF signaling pathway was stimulated by inhibitors, once ERK1/2 phosphorylation was increased in the presence of inhibitors. Moreover, the production of pro-inflammatory cytokine was maintained after treatment with inhibitors and T. gondii proliferation was decreased. In conclusion our study showed that ISO-1 and anti-MIF failed as MIF inhibitors in human placenta. The inhibitory activity of MIF was counterbalanced by increase in intracellular MIF production. This mechanism caused intensification in intracellular signaling and IL-6 secretion and reduction in T. gondii proliferation.