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Evaluation of NLRP3 inflammasome and autophagy in placenta of pregnant women with preeclampsia

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Ingrid Cristina Weel
Total Authors: 1
Document type: Doctoral Thesis
Press: Botucatu. 2016-09-12.
Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Botucatu
Defense date:
Advisor: Maria Terezinha Serrão Peraçoli

Preeclampsia (PE) is a syndrome clinically identified by hypertension and proteinuria and is associated with excessive production of proinflammatory cytokines, deficiency in the production of regulatory cytokines, and increased serum levels of antiphospholipid antibodies (aPLs) in patients with severe forms of PE. aPLs are a family of autoantibodies that react with phospholipid binding proteins, which the main target is beta 2 glycoprotein-I (β2GPI). These antibodies are responsible for inhibiting the differentiation of syncytiotrophoblast and restrict trophoblast migration, resulting in abnormal remodeling of the spiral arterioles, characteristic alteration in PE. The inflammasome is a protein complex that promotes the secretion of the proinflammatory cytokines interleukin-1 beta (IL-1β) and interleukin 18 (IL-18), and also the secretion of high-mobility group box 1 (HMGB1) protein after activation by pathogens and/or endogenous products associated with cellular damage. Autophagy is a pathway of cell degradation or elimination of organelles and proteins by lysosomal processes that are important for the maintenance of cellular homeostasis by promoting the survival of cells in response to stress. The objectives of the present study are: 1. To investigate the proteins related to inflammasome and autophagy in placenta from pregnant women with PE and from normotensive control; 2. To evaluate the relationship between inflammasome and autophagy in human extravillous trophoblast cells (SW.71) induced by aPL. Placental fragments were collected from 20 normotensive pregnant women and from 20 pregnant women with PE to evaluate gene and protein expression of NLRP3, caspase-1, IL-1β, tumor necrosis factor-alpha (TNF-α), IL-18, HMGB1, light chain protein (LC3B- II), beclin-1 and mammalian target of rapamycin (mTOR). The autophagic and inflammatory responses as well as the expression of antiangiogenic factors were also analyzed in SW.71 cells induced by aPL. The results showed higher levels of mRNA for NLRP3, caspase-1, IL-1β, TNF-α and HMGB1 in placental tissue as well as significant increase in caspase-1, IL-1β, TNF-α and HMGB1 levels in placental homogenate from women with PE compared with the normotensive group. Gene and protein expression of IL-18 was significantly decreased in the group of preeclamptic women. The expression of proteins related to autophagy, LC3B-II and beclin-1 and the mRNA levels of these proteins were significantly decreased in placenta of women with PE compared with the normotensive ones. On the other hand, mRNA and protein for mTOR were higher in women with PE. In SW.71 cells it was observed that the treatment with aPL for 8h induced significant decrease in LC3B-II/LC3BI ratio, followed by its significant increase after 72hr of aPL stimulation. These results were not observed in the expression of beclin-1 and p62. When SW.71 cells were submitted to autophagy inhibition a significant increase in IL-1β, IL-8 and soluble endoglin (sEng) was detected, whereas the maintenance of autophagy lead to reduced secretion of sEng and fms-like tyrosine kinase-1-soluble (sFlt-1). Furthermore, the maintenance of the autophagic process significantly reduced the secretion of IL-1β and IL-8 in cells induced by aPL. In conclusion, the results demonstrated that placenta from preeclamptic women shows NLRP3 inflammasome activation and decreased autophagic response suggesting that these processes may contribute to the pathogenesis of PE. The stimulus of extravillous trophoblast cells with aPL caused decrease in the autophagic response in these cells by inflammasome activation, leading to delayed recovery of autophagy, which may probably occur due to an attempted of inflammasome control by the autophagy process. (AU)

FAPESP's process: 13/00535-1 - Evaluation of NLRP3 inflammasome and autophagy in placenta of pregnant women with preeclampsia
Grantee:Ingrid Cristina Weel
Support type: Scholarships in Brazil - Doctorate