BackgroundStress during fetal life increases the risk of affective and immune disorders later in life. The altered peripheral immune response caused by prenatal stress may impact on brain function by the modification of local inflammation. In this study we have explored whether prenatal stress results in alterations in the immune response in the hippocampus of female mice during adult life.MethodsPregnant C57BL/6 mice were subjected three times/day during 45 minutes to restraint stress from gestational Day 12 to delivery. Control non-stressed pregnant mice remained undisturbed. At four months of age, non-stressed and prenatally stressed females were ovariectomized. Fifteen days after surgery, mice received an i.p. injection of vehicle or of 5 mg/kg of lipopolysaccharide (LPS). Mice were sacrificed 20 hours later by decapitation and the brains were removed. Levels of interleukin-1β (IL1β), interleukin-6 (IL-6), tumor necrosis factor α (TNF-α), interferon γ-inducible protein 10 (IP10), and toll-like receptor 4 mRNA were assessed in the hippocampus by quantitative real-time polymerase chain reaction. Iba1 immunoreactivity was assessed by immunocytochemistry. Statistical significance was determined by one-way or two-way analysis of variance.ResultsPrenatal stress, per se, increased IL1β mRNA levels in the hippocampus, increased the total number of Iba1-immunoreactive microglial cells and increased the proportion of microglial cells with large somas and retracted cellular processes. In addition, prenatally stressed and non-stressed animals showed different responses to peripheral inflammation induced by systemic administration of LPS. LPS induced a significant increase in mRNA levels of IL-6, TNF-α and IP10 in the hippocampus of prenatally stressed mice but not of non-stressed animals. In addition, after LPS treatment, prenatally stressed animals showed a higher proportion of Iba1-immunoreactive cells in the hippocampus with morphological characteristics of activated microglia compared to non-stressed animals. In contrast, LPS induced similar increases in expression of IL1β and toll-like receptor 4 in both prenatally stressed and non-stressed animals.ConclusionThese findings indicate that prenatal stress induces long-lasting modifications in the inflammatory status of the hippocampus of female mice under basal conditions and alters the immune response of the hippocampus to peripheral inflammation.

It has been previously reported that the neuroprotective hormone oestradiol reduces microglia inflammatory activity. The objective of this study was to test whether two selective oestrogen receptor modulators, tamoxifen and raloxifene, modulate in vivo the activation of microglia induced by the peripheral administration of lipopolysaccharide (LPS). Activation of microglia was assessed in the white matter of the cerebellum using immunoreactivity for major histocompatability complex-II. Oestradiol, tamoxifen and raloxifene decreased microglia activation induced by LPS in male and ovariectomized female rats, although the doses of oestradiol that were effective in decreasing microglia reactivity were not the same in both sexes. Tamoxifen reduced microglia activation in all experimental groups at all doses tested (0 . 5-2 mg/kg b.w.) while raloxifene lost its anti-inflammatory activity at the higher dose tested (2 mg/kg b.w). In addition, raloxifene had per se a moderate pro-inflammatory activity in the brain of control female rats and its antiinflammatory activity was partially impaired in female animals after 1 month of deprivation of ovarian hormones. Spots of oestrogen receptor (ER)-a immunoreactivity were detected in the soma and cell processes of microglia. Treatment with LPS, oestradiol or tamoxifen induced an increase of ER-a immunoreactive spots in the perikaryon of microglia, while oestradiol antagonized the effect of LPS. The results indicate that some oestrogenic compounds decrease brain inflammation by a mechanism that may involve ERs expressed by microglia. The findings support the potential therapeutic role of oestrogenic compounds as protective anti-inflammatory agents for the central nervous system.

After brain injury, astrocytes acquire a reactive phenotype characterized by a series of morphological and molecular modifications, including the expression of the cytoskeletal protein vimentin. Previous studies have shown that estradiol down-regulates reactive astrogliosis. In this study we assessed whether raloxifene and tamoxifen, two selective estrogen receptor modulators, have effects similar to estradiol in astrocytes. We also assessed whether aging and the timing of estrogenic therapy after ovariectomy influence the action of the estrogenic compounds. Four groups of animals were studied: 1) young rats, ovariectomized at 2 months of age; 2) middle-aged rats, ovariectomized at 8 months of age; 3) aged rats, ovariectomized at 18 months of age; and 4) aged rats, ovariectomized at 2 months and sham operated at 18 months of age. Fifteen days after ovariectomy or sham surgery, animals received a stab wound brain injury and the treatment with the estrogenic compounds. The number of vimentin-immunoreactive astrocytes after injury was significantly higher in the hippocampus of aged rats after a long-term ovariectomy compared with aged animals after a short-term ovariectomy and middle-aged rats. In addition, reactive astrocytes were more numerous in the two groups of aged animals than in young animals. Despite these differences, the estrogenic compounds reduced reactive astrogliosis in all animal groups. These findings indicate that estradiol, raloxifene, and tamoxifen are potential candidates for the control of astrogliosis in young and older individuals and after a prolonged depletion of ovarian hormones.

One of the major limitations associated with platinum use is the resistance that almost invariably develops in different tumor types. In the current study, we sought to identify epigenetically regulated microRNAs as novel biomarkers of platinum resistance in lung and ovarian cancers, the ones with highest ratios of associated chemo-resistance.Methods: We combined transcriptomic data from microRNA and mRNA under the influence of an epigenetic reactivation treatment in a panel of four paired cisplatin -sensitive and -resistant cell lines, followed by real-time expression and epigenetic validations for accurate candidate selection in 19 human cancer cell lines. To identify specific candidate genes under miRNA regulation, we assembled “in silico” miRNAs and mRNAs sequences by using ten different algorithms followed by qRT-PCR validation. Functional assays of site-directed mutagenesis and luciferase activity, miRNAs precursor overexpression, silencing by antago-miR and cell viability were performed to confirm their specificity in gene regulation. Results were further explored in 187 primary samples obtained from ovarian tumors and controls.Results: We identified 4 candidates, miR-7, miR-132, miR-335 and miR-148a, which deregulation seems to be a common event in the development of resistance to cisplatin in both tumor types. miR-7 presented specific methylation in resistant cell lines, and was associated with poorer prognosis in ovarian cancer patients. Our experimental results strongly support the direct regulation of MAFG through miR-7 and their involvement in the development of CDDP resistance in human tumor cells.Conclusion: The basal methylation status of miR-7 before treatment may be a potential clinical epigenetic biomarker, predictor of the chemotherapy outcome to CDDP in ovarian cancer patients. To the best of our knowledge, this is the first report linking the regulation of MAFG by miRNA-7 and its role in chemotherapy response to CDDP. Furthermore, this data highlights the possible role of MAFG as a novel therapeutic target for platinum resistant tumors.