Silibinin Downregulates the NF-κB Pathway and NLRP1/NLRP3 Inflammasomes in Monocytes from Pregnant Women with Preeclampsia

Abstract

Preeclampsia (PE) is a human pregnancy-specific syndrome with abnormal activation of cells from the innate immune system. The present study evaluated whether silibinin (SB) treatment of monocytes from preeclamptic women could modulate NLRP1 and NLRP3 inflammasomes as well as TLR4/NF-κB pathway activation. Peripheral blood monocytes from 20 preeclamptic and 20 normotensive (NT) pregnant women, as well as the THP-1 cell line, were cultured with or without monosodium urate (MSU) or SB. NLRP1, NLRP3, Caspase-1, TLR4, MyD88, NF-κB, IL-1β, IL-18, TNF-α and IL-10 gene expression by monocytes was analysed by quantitative real-time polymerase chain reaction (qPCR), while inflammatory cytokine production and p65NF-κB activity were determined by enzyme-linked immunosorbent assays (ELISAs). TLR4/MyD88/NF-κB and NLRP1/NLRP3 inflammasomes pathways in THP-1 cells were evaluated by flow cytometry and western blot respectively. Compared with NT women, monocytes from preeclamptic women showed The Ethics Committee of the Botucatu Medical School approved the study (protocol number 2.333.216)higher endogenous activation of NLRP1/NLRP3 inflammasomes and the TLR4/NF-κB pathway as well as higher gene and protein expression of IL-1β, IL-18 and TNF-α, and lower expression of IL-10. Monocyte stimulation with MSU increased inflammation-related genes as well as NF-κB activity. In vitro, SB treatment of monocytes from preeclamptic women reduced the basal activation of these cells by decreasing NLRP1/NLRP3 inflammasomes and p65NF-κB activity. THP-1 cells exhibited a similar immunological response profile to monocytes from preeclamptic women when cultured with or without MSU or SB. These results suggest uric acid participates in the systemic inflammatory response characteristic of preeclampsia and that in vitro SB treatment can modulate the sterile inflammation established in monocytes from preeclamptic women.

Diethyl Blechnic Exhibits Anti-Inflammatory and Antioxidative Activity via the TLR4/MyD88 Signaling Pathway in LPS-Stimulated RAW264.7 Cells

“…The NF-κB signaling pathway is important in the pathological process of the inflammatory responses [37]. NF-κB is a key transcription factor in inflammatory responses.…”

Inflammasomes—A Molecular Link for Altered Immunoregulation and Inflammation Mediated Vascular Dysfunction in Preeclampsia

“…Uric acid is known to promote inflammation and endothelial dysfunction [98] and its crystals, monosodium urate (MSU) promote the release of IL-1β via activation of the NLRP3 inflammasome ( Figure 2) [35,38,63,87]. Monocytes from PE women were activated and hence released higher levels of TNF-α, superoxide anion (O 2 − ), and H 2 O 2 compared to monocytes derived from normotensive pregnant women [99].…”

“…The antioxidant and anti-inflammatory properties of SB were assessed via dose-dependent inhibition of H 2 O 2 release, production of TNF-α, IL-10, TGF-β, and prostaglandin E2 (PGE2) following LPS stimulation of peripheral blood monocytes from healthy individuals. Monocytes were treated with SB to determine whether SB can modulate the NLRP1 and NLRP3 inflammasomes, as well as influence upstream TLR-4/NF-κB activation [99]. Administration of SB to MSU-stimulated monocytes reduced the degree of NLRP1 and NLRP3 inflammasome activation, as well as TLR-4/NF-kB activation [99].…”

“…Monocytes were treated with SB to determine whether SB can modulate the NLRP1 and NLRP3 inflammasomes, as well as influence upstream TLR-4/NF-κB activation [99]. Administration of SB to MSU-stimulated monocytes reduced the degree of NLRP1 and NLRP3 inflammasome activation, as well as TLR-4/NF-kB activation [99]. Furthermore, administration of SB to pregnant rats in an experimental model of PE, induced by nitric oxide synthase inhibition (with N-omega-nitro-l-arginine methyl (l-NAME)) protected reproductive outcomes, normalized blood pressure, reduced proteinuria, and also serum levels of pro-inflammatory cytokines [102].…”

The Role of Inflammation in the Pathogenesis of Preeclampsia

“…Mulla et al [ 90 ] and Xie et al [ 88 ] proved that NRLP3 activation in trophoblasts and peripheral blood plays an important role in the pathogenesis of PE. Moreover, enhanced expression of NLRP1 and NLRP3 has been demonstrated in peripheral monocytes from preeclamptic women [ 91 , 92 ]. Additionally, women with PE demonstrate an elevated level of total cholesterol and uric acid which both belong to host-derived damage-associated molecular patterns (DAMPs)—endogenous alarmins [ 93 , 94 ].…”