Aggregation of Human Trophoblast Cells into Three-Dimensional Culture System Enhances Anti-Inflammatory Characteristics through Cytoskeleton Regulation.

BACKGROUND: Three-dimensional (3D) culture changes cell characteristics and function, suggesting that 3D culture provides a more physiologically relevant environment for cells compared with 2D culture. We investigated the differences in cell functions depending on the culture model in human trophoblast cells (Sw.71). METHODS: Sw.71 cells were incubated in 2D monolayers or simple 3D spheroids. After incubation, cells were corrected to assess RNA-seq transcriptome or protein expression, and culture medium were corrected to detect cytokines. To clarify the role of actin cytoskeleton, spheroid Sw.71 cells were treated mycalolide B (inhibitor of actin polymerization) in a 3D culture. RESULTS: RNA-seq transcriptome analysis, results revealed that 3D-cultured cells had a different transcriptional profile compared with 2D-cultured cells, especially regarding inflammation-related molecules. Although interleukin-6 (IL-6) mRNA level was higher in 3D-culured cells, its secretion levels were higher in 2D-cultured cells. In addition, the levels of mRNA and protein expression of regnase-1, regulatory RNase of inflammatory cytokine, significantly increased in 3D culture, suggesting post-translational modification of IL-6 mRNA via regnase-1. Treatment with mycalolide B reduced cell-to-cell contact to build 3D formation and increased expression of actin cytoskeleton, resulting in increased IL-6 secretin. CONCLUSION: Cell dimensionality plays an essential role in governing the spatiotemporal cellular outcomes, including inflammatory cytokine production and its negative regulation associated with regnase-1.

Advanced glycation end products regulate interleukin-1ß production in human placenta.

Maternal obesity is a major risk factor for pregnancy complications, causing inflammatory cytokine release in the placenta, including interleukin-1ß (IL-1ß), IL-6, and IL-8. Pregnant women with obesity develop accelerated systemic and placental inflammation with elevated circulating advanced glycation end products (AGEs). IL-1ß is a pivotal inflammatory cytokine associated with obesity and pregnancy complications, and its production is regulated by NLR family pyrin domain-containing 3 (NLRP3) inflammasomes. Here, we investigated whether AGEs are involved in the activation of NLRP3 inflammasomes using human placental tissues and placental cell line. In human placental tissue cultures, AGEs significantly increased IL-1ß secretion, as well as IL-1ß and NLRP3 mRNA expression. In human placental cell culture, although AGE treatment did not stimulate IL-1ß secretion, AGEs significantly increased IL-1ß mRNA expression and intracellular IL-1ß production. After pre-incubation with AGEs, nano-silica treatment (well known as an inflammasome activator) increased IL-1ß secretion in placental cells. However, after pre-incubation with lipopolysaccharide to produce pro-IL-1ß, AGE treatment did not affect IL-1ß secretion in placental cells. These findings suggest that AGEs stimulate pro-IL-1ß production within placental cells, but do not activate inflammasomes to stimulate IL-1ß secretion. Furthermore, using pharmacological inhibitors, we demonstrated that AGE-induced inflammatory cytokines are dependent on MAPK/NF-κB/AP-1 signaling and reactive oxygen species production in placental cells. In conclusion, AGEs regulate pro-IL-1ß production and inflammatory responses, resulting in the activation of NLRP3 inflammasomes in human placenta. These results suggest that AGEs, as an endogenous and sterile danger signal, may contribute to chronic placental cytokine production.

Moderate Hypoxia Down-Regulates Interleukin-6 Secretion and TLR4 Expression in Human Sw.71 Placental Cells.

BACKGROUND/AIMS: The placenta is a vital organ for pregnancy. Many in vitro placental experiments are conducted under 21% O2; however, O2 tension could influence cellular functions, including cytokine secretion. We investigated the effects of oxygen tension between moderate hypoxia (5% O2) and normoxia (21% O2) by testing the hypothesis that moderate hypoxia regulates cellular phenotypes differently from normoxia in human trophoblast cells. METHODS AND RESULTS: Sw.71 trophoblast cells were incubated under normoxic or moderately hypoxic conditions. Cells were also treated with lipopolysaccharide (LPS) as a Toll-like receptor 4 (TLR4) ligand inducing inflammation. Interleukin-6 (IL-6) as an inflammatory cytokine was determined, and TLR4, hypoxia-induced factor-1α (HIF1α), and reactive oxygen species (ROS) production were detected. Moderate hypoxia increased HIF1α expression and cell proliferation and acted by two different mechanisms to decrease IL-6 secretion compared with normoxia: it limits the TLR4 expression and ROS production. Treatment with cobalt chloride as an HIF1 activator inhibited IL-6 secretion and TLR4 expression; this effect was reversed on treatment with PX-12 as an HIF1 suppressor. CONCLUSION: IL-6 secretion, TLR4 expression, and ROS production, classical markers of inflammation, are down-regulated by moderate hypoxia, and HIF1α and ROS have a potential to regulate these responses in human trophoblast cells.

Olive Leaf Extract (OleaVita) Suppresses Inflammatory Cytokine Production and NLRP3 Inflammasomes in Human Placenta.

The placenta is essential for pregnancy and produces both pro-inflammatory and anti-inflammatory cytokines. Excessive production of inflammatory cytokines, involving interleukin-1ß (IL-1ß), IL-6, and IL-8, from placental tissues is associated with pregnancy complications. Olive leaf extract has several health benefits, including anti-inflammatory functions. OleaVita is a new commercial olive leaf extract; it is hypothesized to suppress placental inflammation. In human placental tissue culture, OleaVita treatment inhibited the secretion of inflammatory cytokines and NF-κB p65 protein expression. OleaVita also suppressed toll-like receptor ligands-induced IL-1ß secretion in human placental tissues. IL-1ß is regulated by the NLRP3 inflammasomes, a pivotal regulator of various diseases. OleaVita significantly decreased NLRP3 and pro-IL-1ß protein expression, suggesting that it has an inhibitory effect on NLRP3 inflammasome activation. Thus, OleaVita is beneficial as an inhibitor of inflammation and NLRP3 inflammasome activation, and may be used as a supplement for the treatment and prevention of inflammatory diseases.

Oxygen concentration modulates cellular senescence and autophagy in human trophoblast cells.

PROBLEM: We investigated the effect of oxygen concentrations on cellular senescence and autophagy and examined the role of autophagy in human trophoblast cells. METHOD OF STUDY: Human first-trimester trophoblast cells (Sw.71) were incubated under 21%, 5%, or 1% O2 concentrations for 24 hours. We examined the extent of senescence caused using senescence-associated ß-galactosidase (SA-ß-Gal) and senescence-associated secretory phenotype (SASP) as markers. Moreover, we examined the role of autophagy in causing cellular senescence using an autophagy inhibitor (3-methyladenine, 3MA). RESULTS: Physiological normoxia (5% O2 ) decreased SA-ß-Gal-positive cells and SASP including interleukin-6 (IL-6) and IL-8 compared with cultured cells in 21% O2 . Pathophysiological hypoxia (1% O2 ) caused cytotoxicity, including extracellular release of ATP and lactate dehydrogenase, and decreased senescence phenotypes. 3MA-treated trophoblast cells significantly suppressed senescence markers (SA-ß-Gal-positive cells and SASP secretion) in O2 -independent manner. CONCLUSION: We conclude that O2 concentration modulates cellular senescence phenotypes regulating autophagy in the human trophoblast cells. Moreover, inhibiting autophagy suppresses cellular senescence, suggesting that autophagy contributes to oxygen stress-induced cellular senescence.

Palmitic acid stimulates interleukin-8 via the TLR4/NF-κB/ROS pathway and induces mitochondrial dysfunction in bovine oviduct epithelial cells.

PROBLEM: We investigated the effect of palmitic acid (PA), a major saturated fatty acid in NEFA, on bovine oviduct epithelial cells (OECs) during in vitro cell culture. METHOD OF STUDY: Bovine oviductal tissues ipsilateral to the corpus luteum were collected 1-3 days after ovulation; the OECs were isolated and cultured. RESULTS: PA increased lipid accumulation and activated caspase-3 in OECs, resulting in decreased cell proliferation. PA also stimulated the secretion of inflammatory cytokine interleukin (IL)-8 depending on TLR4, NF-κB activation, and reactive oxygen species (ROS) production. Moreover, PA induced mitochondrial dysfunction, including mitochondrial fission, ATP production, and mitochondrial ROS production. It also increased levels of LC3 and p62 proteins, suggesting autophagy induction in OECs. CONCLUSION: We suggest that bovine OECs recognize an excessive increase in endogenous and sterile danger signals, such as PA, which may contribute to chronic oviductal inflammation, resulting in infertility associated with oviductal dysfunction.

Advanced glycation end products and lipopolysaccharides stimulate interleukin-6 secretion via the RAGE/TLR4-NF-κB-ROS pathways and resveratrol attenuates these inflammatory responses in mouse macrophages.

Macrophages are essential for regulating the physiology of pregnancy; however, excessive inflammatory responses to macrophages, induced by infection and/or endogenous danger signals, may potentially result in complications during pregnancy. Advanced glycation end-products (AGE) and lipopolysaccharides (LPS) are known to induce inflammation and are associated with adverse developmental outcomes. The aim of the present study was to examine the effect of AGE and LPS on cytokines in the J774 murine macrophage cell line and the potential effect of resveratrol on AGE- and LPS-induced inflammation in macrophages. AGE and LPS significantly increased IL-6 mRNA expression and secretion in J774 macrophages (P<0.05). Although AGE and LPS significantly stimulated IL-1ß mRNA expression (P<0.05), they had no significant effect on IL-1ß secretion. To assess the receptors for AGE and LPS, including receptor for AGE (RAGE) and Toll-like receptor (TLR4), blocking reagents (RAGE antagonist or TLR4 inhibitor) were added to the J774 macrophages. IL-6 secretion induced by AGE or LPS was significantly inhibited by pretreatment with RAGE antagonist (P<0.05) or TLR4 inhibitor (P<0.05). IL-6 secretion was dependent on nuclear factor (NF)-κB activation and the production of reactive oxygen species (ROS; P<0.05). Resveratrol suppressed mRNA expression and intracellular IL-6 production, resulting in significantly decreased IL-6 secretion after treatment with LPS or AGE (P<0.01). Furthermore, treatment with Ex527, which is a sirtuin-1 (SIRT1) inhibitor, significantly attenuated the anti-inflammatory effect of resveratrol (P<0.05), and treatment with 5-aminoimidazole-4-carboxamide ribonucleotide, which is a 5' adenosine monophosphate-activated protein kinase (AMPK) activator, resulted in a significant decrease in IL-6 secretion in J774 macrophages (P<0.05). The results of the present study indicated that AGE and LPS increase IL-6 secretion depending on NF-κB activation and ROS production through RAGE and/or TLR4 in the J774 murine macrophage cell line. Based on the present study, resveratrol appears to be an effective regulator of the inflammatory responses associated with SIRT1 and AMPK activation in macrophages. These results suggest that resveratrol may have therapeutic applications for controlling immune responses during pregnancy.

Interferon Tau Regulates Cytokine Production and Cellular Function in Human Trophoblast Cell Line.

Type I interferons (IFN), including IFN-beta (IFNB), activate multiple STAT signaling to drive various biological responses. Another type I IFN, IFN-tau (IFNT), secreted by ruminant embryonic trophoblast cells, has multiple functions with low cytotoxicity. Here, we examined the effects of IFNT on human trophoblast cell functions. First, we performed next-generation sequencing and demonstrated that IFNT-dependent changes in the human Sw.71 trophoblast cell line are partly mediated by proinflammatory as well as IFN signaling. Next, we validated candidate genes, and data confirmed that IFNT stimulated interleukin-6 (IL-6) and IL-8 mRNA expression and secretion. However, human IFNB did not affect IL-6 and IL-8 mRNA expression and secretion. IFNT-induced cytokine secretion was dependent on STAT3 signaling, but not STAT1 signaling. In addition, treatment with IFNT, IL-6, or IL-8 increased cell proliferation, and IFNT also stimulated cell migration in human trophoblast cells. Although IFNT did not affect superoxide dismutase (SOD) 1 mRNA expression, it clearly increased mitochondrial SOD2 mRNA expression, resulting in the acceleration of SOD activity. We demonstrated that in addition to IFN signaling, IFNT also regulated inflammation-related signaling as well as cell proliferation, migration, and redox signaling in human trophoblast cells.

AGEs and HMGB1 Increase Inflammatory Cytokine Production from Human Placental Cells, Resulting in an Enhancement of Monocyte Migration.

PROBLEM: Advanced glycation end products (AGEs) and high-mobility group box-1 (HMGB1) are considered contributing to placental inflammation. We examined the effect of AGEs and HMGB1 on cytokines from Sw.71 human trophoblast cell lines and the interactions between Sw.71 cells and THP-1-monocytes. METHODS OF STUDY: Sw.71 cells were cultured with/without AGEs or HMGB1. We examined the role of AGEs or HMGB1 on THP1 migration and effect of AGEs on IL-6 from Sw.71 cells using co-cultures or conditioned medium from THP-1 cells. RESULTS: AGEs and HMGB1 increased interleukin (IL)-6, IL-8, and chemokine C-C motif ligand 2 (CCL2) secretion from Sw.71 cells. The secretion of IL-6 was dependent on reactive oxygen species (ROS) and NF-κB. AGEs stimulated IL-6 secretion through receptor RAGE and TLR4, whereas HMGB1 stimulated it through TLR4. AGEs, but not HMGB1, increased monocyte migration via IL-8 and CCL2 from Sw.71 cells. THP-1 monocytes induced IL-6 secretion from Sw.71 cells, and AGEs further stimulated it. CONCLUSIONS: AGEs and HMGB1 may promote sterile placental inflammation cooperating with monocytes/macrophages.

Palmitic acid induces interleukin-1ß secretion via NLRP3 inflammasomes and inflammatory responses through ROS production in human placental cells.

Maternal obesity, a major risk factor for adverse pregnancy complications, results in inflammatory cytokine release in the placenta. Levels of free fatty acids are elevated in the plasma of obese human. These fatty acids include obesity-related palmitic acids, which is a major saturated fatty acid, that promotes inflammatory responses. Increasing evidence indicates that nucleotide-binding oligomerization domain-like receptor pyrin domain-containing 3 (NLRP3) inflammasomes mediate inflammatory responses induced by endogenous danger signals. We hypothesized that inflammatory responses associated with gestational obesity cause inflammation. To test this hypothesis, we investigated the effect of palmitic acid on the activation of NLRP3 inflammasomes and inflammatory responses in a human Sw.71 trophoblast cell line. Palmitic acid stimulated caspase-1 activation and markedly increased interleukin (IL)-1ß secretion in Sw.71 cells. Treatment with a caspase-1 inhibitor diminished palmitic acid-induced IL-1ß release. In addition, NLRP3 and caspase-1 genome editing using a CRISPR/Cas9 system in Sw.71 cells suppressed IL-1ß secretion, which was stimulated by palmitic acid. Moreover, palmitic acid stimulated caspase-3 activation and inflammatory cytokine secretion (e.g., IL-6 and IL-8). Palmitic acid-induced cytokine secretion were dependent on caspase-3 activation. In addition, palmitic acid-induced IL-1ß, IL-6, and IL-8 secretion was depended on reactive oxygen species (ROS) generation. In conclusion, palmitic acid caused activation of NLRP3 inflammasomes and inflammatory responses, inducing IL-1ß, IL-6, and IL-8 secretion, which is associated with ROS generation, in human Sw.71 placental cells. We suggest that obesity-related palmitic acid induces placental inflammation, resulting in association with pregnancy complications.