Modulatory effect of silibinin on NLRP3 inflammasome induced by monosodium urate in monocytes from pregnant women with preeclampsia

Abstract

Preeclampsia (PE) is a specific gestational syndrome, characterized by intense systemic inflammatory reaction, which contributes significantly to the pathogenesis of the disease. Monocytes of preeclamptic women are endogenously activated and produce high levels of the inflammatory cytokines interleukin-1beta (IL-1b) and tumor necrosis factor alpha (TNF-a) detected in plasma and also express activation of the nuclear transcription factor NF-kB and the molecular complex NLRP3 inflammasome, responsible for release of biologically active inflammatory cytokines. The association between hyperuricemia, increased production of free radicals derived from oxygen as well as elevated TNF-± production by monocytes of pregnant women with PE suggest the participation of uric acid as mediator of the inflammatory response. In addition, the in vitro stimulation of monocytes with uric acid induces activation of the NLRP3 inflammasome and the production of elevated levels of IL-1b. Silibinin is the main active component of silymarin, a polyphenolic complex derived from fruits and seeds of Silybum marianum and has important anti-inflammatory and anti-oxidant activities. This flavonoid exerts an inhibitory effect on the transcription factor NF-kB essential for the expression of inflammatory cytokines and other mediators of inflammation. Therefore, the present project aims to investigate whether silibinin has modulatory effect on NLRP3 inflammasome and NF-kB expression in monocytes obtained from pregnant women with PE and from normotensive pregnant women stimulated in vitro with monosodium urate (MSU). Peripheral blood monocytes obtained from 20 preeclamptic women and 20 normotensive pregnant women in the third trimester of gestation will be cultured in the presence or absence of silibinin and MSU. The modulatory effect of silibinin on NF-kB will be evaluated by determining the p65 protein of NF-kB in nuclear extract of the cells by enzyme-linked immunosorbent assay, and gene expression of the NLRP3 receptor, caspase-1, IL-1b and TNF-± will be determined by RT-qPCR. (AU)