Trophoblastic mitochondrial DNA induces endothelial dysfunction and NLRP3 inflammasome activation: Implications for preeclampsia.

AIMS: Preeclampsia (PE) is characterised by systemic vascular endothelium dysfunction. Circulating trophoblastic secretions contribute to endothelial dysfunction, resulting in PE; however, the underlying mechanisms remain unclear. Herein, we aimed to determine the potential correlation between the release of trophoblastic mitochondrial deoxyribonucleic acid (DNA) (mtDNA) and endothelium damage in PE. MATERIALS AND METHODS: Umbilical cord sera and tissues from patients with PE were investigated for inflammasome activation. Following this, trophoblastic mitochondria were isolated from HTR-8/SVneo trophoblasts under 21 % oxygen (O2) or hypoxic conditions (1 % O2 for 48 h) for subsequent treatments. Primary human umbilical veinendothelial cells (HUVECs) were isolated from the human umbilical cord and then exposed to a vehicle (phosphate-buffered saline [PBS]), mtDNA, hypo-mtDNA, or hypo-mtDNA with INF39 (nucleotide oligomerisation domain-like receptor family pyrin domain containing 3 [NLRP3]-specific inhibitor) for 12 h before flow cytometry and immunoblotting. The effects of trophoblastic mtDNA on the endothelium were further analysed in vivo using enzyme-linked immunosorbent assay (ELISA) and vascular reactivity assay. The effects of mtDNA on vascular phenotypes were also tested on NLRP3 knockout mice. RESULTS: Elevated interleukin (IL)-1ß in PE sera was accompanied by NLRP3 inflammasome activation in cord tissues. In vitro and in vivo experiments revealed that the release of trophoblastic mtDNA could damage the endothelium via NLRP3 activation, resulting in the overexpression of NLRP3, caspase-1 p20, IL-1ß p17, and gasdermin D (GSDMD); reduced endothelial nitric oxide synthase (eNOS) levels; and impaired vascular relaxation. Flow cytometric analysis confirmed that extensive cell death was induced by mtDNA, and simultaneously, a more pronounced pro-apoptotic effect was caused by hypoxia-treated trophoblastic mtDNA. The NLRP3 knockout or pharmacologic NLRP3 inhibition partially reversed tumour necrosis factor-α (TNF-α) and IL-1ß levels and endothelium-dependent vasodilation in mice. CONCLUSION: These findings demonstrate that trophoblastic mtDNA induced NLRP3/caspase-1/IL-1ß signalling activation, eNOS-related endothelial injury, and vasodilation dysfunction in PE.

[Characteristics of soil anti-scouribility in gully head wall of grass-covering on the gullied Loess Plateau, Northwest China]. / 黄土高塬沟壑区草地沟头立壁土壤抗冲性特征.

Vegetation restoration in the Chinese Loess Plateau has significantly changed soil erosion process of gully head wall. In order to investigate the characteristics and controlling factors of soil anti-scour properties of gully head covered by grasses, we carried out indoor undamaged soil trench scouring tests. By using barren gully head as the control, the physical and chemical properties and anti-scouring characteristics of soil in different soil layers (0-10, 10-20, 20-40, 40-60, 60-80, 80-100 cm) of the vertical wall of gully with grass cover were analyzed. The results showed that water-stable aggregate content and cohesion in barren and grass-covering gully head decreased with soil depth. Soil organic matter content and soil anti-scouribility coefficient in barren gully head decreased with soil depth, while the two indicators for gully head covered by grass increased firstly and then decreased with soil depth, with the maximum value (24.30 g·kg-1 and 58.86 L·g-1) in 10-20 cm soil layer. Meanwhile, the soil anti-scouring coefficient in each soil layer of grass-covering gully head was 1.7-9.3 times of that in soil layer of barren gully head. Soil organic matter content, water-stable aggregate content, cohesion and root length density all presented significantly positive correlation with soil anti-scouribility, among which soil organic matter content had the highest coefficient (r=0.98). Results of this study might provide basic data for the study of headcut erosion mechanism in Loess Plateau gully region, and scientific basis for effective control of soil and water loss in this region.

Osmotic water permeability diversification in primary trophoblast cultures from aquaporin 1-deficient pregnant mice.

AIM: Aquaporins (AQP) are water channel proteins, and some play an important role in maternal-fetal fluid exchange. The present study aimed to measure the osmotic water permeability in primary cultures of trophoblast cells from AQP1-deficient (AQP1(-/-) ) pregnant mice and to define the quantitative role of AQP1 in water transport across the trophoblast plasma membrane. MATERIAL AND METHODS: Trophoblast cells were obtained from placental tissue cell culture of AQP1(-/-) pregnant mice and were characterized by cytokeratin 7 immunostaining. The expression of the AQP1 gene in trophoblast cells of wild-type (AQP1(+/+) ) mice was confirmed by immunofluorescence. The osmotic water permeability of trophoblast plasma membranes was measured by a calcein fluorescence quenching method in response to osmotic gradients. RESULTS: A primary cell culture system for trophoblasts was successfully established. Immunofluorescence showed the expression of AQP1 in the trophoblast cell membrane of AQP1(+/+) mice. The osmotic water permeability of AQP1(-/-) trophoblast cells was significantly lower than that in AQP1(+/+) trophoblast cells, in response to both hypotonic and hypertonic challenges. CONCLUSION: The results suggest an important role of AQP1-mediated plasma membrane water permeability in maternal-fetal fluid balance and also provide a potential direction for the identification of therapeutic targets for the treatment of abnormalities in amniotic fluid volume.

Maternal-fetal fluid balance and aquaporins: from molecule to physiology.

Maternal-fetal fluid balance is critical during pregnancy, and amniotic fluid is essential for fetal growth and development. The placenta plays a key role in a successful pregnancy as the interface between the mother and her fetus. Aquaporins (AQPs) form specific water channels that allow the rapid transcellular movement of water in response to osmotic/hydrostatic pressure gradients. AQPs expression in the placenta and fetal membranes may play important roles in the maternal-fetal fluid balance.

Pregnant phenotype in aquaporin 8-deficient mice.

AIM: Aquaporin 8 (AQP8) is expressed within the female reproductive system but its physiological function reminds to be elucidated. This study investigates the role of AQP8 during pregnancy using AQP8-knockout (AQP8-KO) mice. METHODS: Homozygous AQP8-KO mice were mated, and the conception rate was recorded. AQP8-KO pregnant mice or their offspring were divided into 5 subgroups according to fetal gestational day (7, 13, 16, 18 GD) and newborn. Wild type C57 pregnant mice served as the control group. The number of pregnant mice, total embryos and atrophic embryos, as well as fetal weight, placental weight and placental area were recorded for each subgroup. The amount of amniotic fluid in each sac at 13, 16, and 18 GD was calculated. Statistical significance was determined by analysis of variance of factorial design and chi-square tests. RESULTS: Conception rates did not differ significantly between AQP8-KO and wild type mice. AQP8-KO pregnant mice had a significantly higher number of embryos compared to wild type controls. Fetal/neonatal weight was also significantly greater in the AQP8-KO group compared to age-matched wild type controls. The amount of amniotic fluid was greater in AQP8-KO pregnant mice than wild type controls, although the FM/AFA (fetal weight/amniotic fluid amount) did not differ. While AQP8-KO placental weight was significantly larger than wild type controls, there was no evidence of placental pathology in either group. CONCLUSION: The results suggest that AQP8 deficiency plays an important role in pregnancy outcome.