Association among placental 11ß-HSD2, PPAR-γ, and NF-κB p65 in small-for-gestational-age infants: A nested case-control study.

PROBLEM: 11ß-Hydroxysteroid dehydrogenase 2 (11ß-HSD2) catalyzes active glucocorticoids into their inactive products, preventing the passage of glucocorticoids into the fetus from maternal circulation. Peroxisome proliferator-activated receptor (PPAR)γ is a member of the nuclear receptor superfamily that regulates the expression of placental 11ß-HSD2. Nuclear factor-kappa B (NF-κB) is a transcription factor that regulates inflammatory signaling. This study aimed to investigate the association among 11ß-HSD2, PPAR-γ, and NF-κB p65 in small-for-gestational-age (SGA) infants. METHOD OF STUDY: Forty-six SGA and 46 appropriate-for-gestational-age (AGA) infants were enrolled in this study. Both newborns and placentas were weighed. Placental 11ß-HSD2 levels were measured using Western blotting. Placental PPAR-γ and NF-κB p65 were detected by immunohistochemistry. Placental inflammatory cytokines were evaluated by real-time RT-PCR. RESULTS: 11ß-HSD2 levels were lower in SGA placentas than those in AGA placentas. Placental PPAR-γ-positive nuclei were less in SGA than those in AGA. By contrast, placental NF-κB p65-positive nuclei were more in SGA than those in AGA. The levels of CRP, TNF-α, IL-8, and IL-1ß, several inflammatory cytokines, were higher in SGA placentas. Correlation analysis showed that neonatal weight was positively associated with PPAR-γ and 11ß-HSD2 in SGA placentas. By contrast, neonatal weight was inversely correlated with NF-κB p65 in SGA placentas. 11ß-HSD2 was positively correlated with PPAR-γ in SGA placentas. CONCLUSIONS: Inflammation-associated downregulation of placental PPAR-γ and 11ß-HSD2 may be involved in SGA.

Vitamin D Deficiency Attenuates Acute Alcohol-Induced Hepatic Lipid Accumulation in Mice.

Vitamin D deficiency has been frequently reported in chronic liver disease. However, its influence on hepatic lipid accumulation in alcoholic liver disease remains unclear. The present study investigated the effects of vitamin D deficiency on acute alcohol-induced hepatic lipid metabolism in mice. Mice were fed with vitamin D deficient diet, in which vitamin D was depleted for 12 weeks to establish an animal model of vitamin D deficiency. Some mice were administered a single gavage of alcohol (4 g/kg bodyweight) before they were euthanized. Results show that feeding mice with vitamin D deficient diet did not induce hepatic lipid accumulation. In contrast, vitamin D deficiency markedly reduced alcohol-induced triacylglycerol (TAG) content and prevented hepatic lipid accumulation. Moreover, vitamin D deficiency significantly attenuated alcohol-induced sterol-regulated element-binding protein (SREBP)-1c activation, which regulates genes for hepatic fatty acid (FA) and TAG synthesis, and the expression of its target genes fatty acid synthase (Fasn) and acetyl-coenzyme- A carboxylase (Acc). In addition, vitamin D deficiency alleviated alcohol-induced downregulation of hepatic nuclear peroxisome proliferator-activated receptor (PPAR)α, which governs FA transport and ß-oxidation, and the expression of Carnitine palmitoyltransferase (Cpt)-1α, cytochrome P450, family 4, subfamily a, polypeptide (Cyp4a)10, and Cyp4a14, which are key enzymes for hepatic fatty acids ß-oxidation and ω-oxidation. Taken together, these results suggest that vitamin D deficiency is not a direct risk factor for hepatic lipid accumulation. Vitamin D deficiency alleviates acute alcohol-induced hepatic lipid accumulation through inhibiting hepatic de novo fatty acid syntheses and promoting fatty acid ß-oxidation and ω-oxidation.

Lipopolysaccharide Downregulates 11ß-Hydroxysteroid Dehydrogenase 2 Expression through Inhibiting Peroxisome Proliferator-Activated Receptor-γ in Placental Trophoblasts.

It is increasingly recognized that excessive glucocorticoids induce fetal intrauterine growth restriction (IUGR). Placental 11ß-hydroxysteroid dehydrogenase 2 (11ß-HSD2), a glucocorticoid-catalyzing enzyme, prevents active glucocorticoids from maternal circulation into the fetus, thus protecting against IUGR. Previous studies demonstrated gestational LPS exposure caused fetal IUGR. The aim of the current study was to investigate the effects of LPS on 11ß-HSD2 in mice placentas and human placental trophoblasts. Pregnant ICR(CD-1) mice were i.p. injected with LPS (200 µg/kg) on gestational day 16. As expected, gestational LPS exposure downregulated 11ß-HSD2 in mice placentas. In vitro, LPS downregulated 11ß-HSD2 in human placental trophoblasts. Additional experiment showed that LPS, which activated NF-κB, suppressed rosiglitazone-induced activation of peroxisome proliferator-activated receptor-γ (PPARγ) in mice placentas and human placental trophoblasts. Moreover, NF-κB p65 knockdown and specific NF-κB inhibitor attenuated LPS-induced suppression of PPARγ nuclear translocation in human placental trophoblasts. In addition, NF-κB p65 knockdown attenuated LPS-induced downregulation of 11ß-HSD2 in human placental trophoblasts. Mechanically, LPS promoted physical interaction between NF-κB p65 and PPARγ in the cytoplasm and nucleus of placental trophoblasts. Finally, pretreatment with rosiglitazone, a PPARγ agonist, partially alleviated LPS-induced reduction of fetal weight and crown-rump length. Taken together, these results suggest that LPS downregulates 11ß-HSD2 through suppressing PPARγ in placental trophoblasts. Placental 11ß-HSD2 downregulation may contribute partially to LPS-induced fetal IUGR.

Maternal cadmium exposure reduces placental zinc transport and induces fetal growth restriction in mice.

Cadmium (Cd) is linked with increased risk of fetal growth restriction (FGR). Nevertheless, the mechanism remains unknown. This study established a mouse model of Cd-induced FGR through two exposure methods. Pregnant mice were either administered with CdCl2 (5, 50 and 250ppm) throughout pregnancy through drinking water or intraperitoneally injected with CdCl2 (4.5mg/kg) on GD9. As expected, fetal weight and crown-rump length were reduced in a gender-independent manner. Interestingly, Mt1 and Mt2, two metallothionein genes, were up-regulated in maternal liver. Correspondingly, Cd accumulated mainly in maternal liver and kidney, and only trace amounts of Cd could pass from dam to placentas and fetuses. Further analysis showed that placental Zn concentration was elevated. Conversely, embryonic Zn concentration was reduced. Moreover, placental Znt1 and Znt2, two zinc transporters, were down-regulated in Cd-exposed mice. These results suggest that maternal Cd exposure during pregnancy reduces placental Zn transport and induces fetal growth restriction.

Rosiglitazone pretreatment protects against lipopolysaccharide-induced fetal demise through inhibiting placental inflammation.

Peroxisome proliferator-activated receptor (PPAR)-γ is highly expressed in human and rodent placentas. Nevertheless, its function remains obscure. The present study investigated the effects of rosiglitazone, a PPAR-γ agonist, on LPS-induced fetal death. All pregnant mice except controls were intraperitoneally injected with LPS (150 µg/kg) daily from gestational day (GD)15 to GD17. As expected, maternal LPS injection caused placental inflammation and resulted in 63.6% fetal death in dams that completed the pregnancy. Interestingly, LPS-induced fetal mortality was reduced to 16.0% when pregnant mice were pretreated with RSG. Additional experiment showed that rosiglitazone pretreatment inhibited LPS-induced expressions of tumor necrosis factor (Tnf)-α, interleukin (Il)-1ß, Il-6, macrophage inflammatory protein (Mip)-2 and keratinocyte-derived chemokine (Kc) in mouse placenta. Although rosiglitazone had little effect on LPS-evoked elevation of IL-10 in amniotic fluid, it alleviated LPS-evoked release of TNF-α and MIP-2 in amniotic fluid. Further analysis showed that pretreatment with rosiglitazone, which activated placental PPAR-γ signaling, simultaneously suppressed LPS-evoked nuclear factor kappa B (NF-κB) activation and blocked nuclear translocation of NF-κB p65 and p50 subunits in trophoblast giant cells of the labyrinth layer. These results provide a mechanistic explanation for PPAR-γ-mediated anti-inflammatory activity in the placentas. Overall, the present study provides additional evidence for roles of PPAR-γ as an important regulator of placental inflammation.