Regulatory mechanisms underlying endoplasmic reticulum stress involvement in the development of gestational diabetes mellitus entail the CHOP-PPARα-NF-κB pathway.

OBJECTIVE: We investigated the proinflammatory functions of endoplasmic reticulum stress and peroxisome proliferator-activated receptor α (PPARα) in the development of gestational diabetes mellitus (GDM) and their relationship in regulating inflammation in GDM. METHODS: This study was performed on placentas of normal pregnant women, women with GDM, and HTR8 cells. Transmission electron microscopy, immunohistochemistry, Western blot analysis, and RT-PCR were performed to analyze ERS and PPARα expression on both normal and GDM pregnancy placentas. ELISA was performed to analyze inflammatory biomarkers. To generate models of the GDM-like state, placentas of normal pregnancy were treated with LPS and polyinosinic-polycytidylic acid (poly [I:C]). TG, CHOP plasmid, and CHOP siRNA were assessed as to their regulation of HTR8 cells to discern the relationship between ERS and PPARα in regulating the inflammation associated with GDM. RESULTS: ERS was elevated in GDM placentas, induced the secretion of IL-6 and TNF-α, and attenuated the expression of GLUT-4. PPARα was diminished in GDM placentas and inhibited the inflammatory responses via the NF-κB nuclear-transport process. 4-PBA reduced CHOP and augmented PPARα, and it decreased IL-6 and TNF-α in our GDM-like explant. However, with both 4-PBA and MK886 treatment, we noted no significant difference in CHOP expression. The level of PPARα was reduced, and that of NF-κB p65 in the nucleus was elevated with TG treatment in the HTR8/Svneo. Knockdown of CHOP increased PPARα and reduced NF-κB p65, while expression of PPARα declined, and that of NF-κB p65 rose with the application of CHOP when HTR8 cells were treated with TG. CONCLUSIONS: ERS contributes to the pathophysiology of GDM in pregnancy via the CHOP-PPARα-NF-κB-signalling pathway by inducing aberrant activation of inflammation and insulin resistance.

Modulating circulating sFlt1 in an animal model of preeclampsia using PAMAM nanoparticles for siRNA delivery.

INTRODUCTION: Excessive circulating sFlt1 plays a major role in the pathogenesis of preeclampsia (PE). Using RNAi to silence sFlt1 may be a therapy for treating PE. Because of the rapid degradation of siRNA, gene therapy in vivo remains limited. Poly-amidoamine (PAMAM) has been demonstrated to be an excellent nanocarrier for siRNA delivery with no discernible toxicity. METHODS: The aim of the present study was to investigate the therapeutic effect of siRNA-sFlt1-PAMAM on PE. The biophysical properties of siRNA-sFlt1-PAMAM complexes were analysed. Next, HTR-8/SVneo cells were incubated with the complexes. The transfection efficiency, silencing effect, and cell proliferation were examined. The timed pregnant rats were grouped to test the in vivo effect of siRNA-sFlt1-PAMAM on PE. The PE model was established by injection of tumour necrosis factor-α (TNF-α), while treatment group rats were injected with both TNF-α and siRNA-sFlt1-PAMAM. The mean arterial pressure, serum levels of sFlt1, and 24-h urinary protein were measured. The number of viable pups, and weights of individual pups and placentae were determined. RESULTS: siRNA-sFlt1-PAMAM complexes showed high cellular uptake and excellent siRNA encapsulation ability. siRNA-sFlt1-PAMAM significantly decreased sFlt1 secretion from HTR-8/SVneo cells (p = 0.001) with little effect on HTR-8/SVneo cell proliferation. The circulating level of sFlt1, mean arterial pressure, and urine protein level in the TNF-α group were significantly increased compared to that in the control group, while the weights of foetuses and placentae were significantly decreased compared to that in the control group (p < 0.05). All preeclamptic symptoms were greatly attenuated by siRNA-sFlt1-PAMAM (p < 0.05). CONCLUSIONS: These data suggest that siRNA-sFlt1-PAMAM effectively decreased sFlt1 secretion and improved pregnancy outcomes in a preeclamptic rat model, which may provide a new therapeutic strategy for PE.

Upregulation of VEGF by small activating RNA and its implications in preeclampsia.

INTRODUCTION: Preeclampsia is a severe pregnancy complication mostly due to inadequate vascular dilation and remodeling of spiral arteries. VEGF, the major factor for angiogenesis, is necessary for modulating angiogenic processes in the placenta. Hence reduction of VEGF in gestational hypertension may also lead to hypoperfusion and subsequent hypoxia of the fetus in hypertensive pregnancy. METHODS: This study aimed at elucidating the mechanism of action of VEGF in preeclampsia. Small activating RNAs (saRNA) were used to upregulate VEGF expression in human trophoblast cells (HTR-8/SVneo). The VEGF expression level was analyzed by real-time quantitative PCR and western blot, while its transfection efficiency was measured by flow cytometer assay. Cell migration was analyzed by a wound scratch assay. NO secretion was detected by determining NO metabolites. eNOS expression was analyzed by western blot. Tube formation function of cells was then analyzed by matrigel migration assay. RESULTS: VEGF expression significantly increased after saRNA transfection (all p ＜ 0.05). NO secretion and eNOS expression significantly increased by saRNA in HTR-8/SVneo cells (p = 0.0003 and 0.032 respectively). The migration ability and tube formation function of HTR-8/SVneo cells were enhanced by saRNA (p = 0.024 and 0.013 respectively). TNF-α inhibited VEGF-downstream eNOS-NO pathway activity as well as cell migration and tubulogenesis, while enforcing the expression of VEGF attenuated all the insults induced by TNF-α. CONCLUSIONS: Utilizing an RNA activation strategy to increase endogenous VEGF expression could be an emerging and effective approach for the treatment of preeclampsia.

Downregulation of Mitofusin 2 in Placenta Is Related to Preeclampsia.

Background. Mitofusin 2 (Mfn2) is a novel mitochondrial protein that is implicated in cellular proliferation and metabolism; however, the role of Mfn2 in preeclampsia (PE) remains unknown. This study aimed to explore the relationship between Mfn2 and PE. Method. Preeclamptic and normal pregnancies were enrolled in a comparative study. The expression of Mfn2 in placenta was detected by qRT-PCR. And the mitochondrial function was detected by ATP assay. Then TEV-1 cells were cultured in hypoxic conditions. mRNA and protein expressions of Mfn2 were detected by qRT-PCR and western blot separately. Cells' viability was detected by MTT. And the mitochondrial function was detected by ATP and mitochondrial membrane potential (MMP) assay. We further knocked down the Mfn2 gene in TEV-1 cells and evaluated the cells' viability. Results. Mfn2 and ATP expressions were significantly decreased in preeclamptic placentae compared to normal placentae. Mfn2 expression level and the viability of TEV-1 cells were reduced during hypoxic conditions. TEV-1 cells' viability, ATP, and MMP levels were also significantly decreased after knockdown of the Mfn2 gene. Conclusions. These results suggest that defects in Mfn2 could cause mitochondrial dysfunction and decrease trophoblastic cells' viability. Therefore, Mfn2 may be functionally involved in the pathogenesis of PE.