Inhibition of trophoblast invasiveness in vitro by immunoneutralization of leptin in the bat, Myotis lucifugus (Chiroptera)

Materno-foetal leptin and insulin-like growth factor in low birth weight neonates

Low birth weight (LBW) is a health concern in developing countries. Leptin and insulin-like growth factor-I (IGF-I) are factors that influence LBW. A case-control study was conducted at Medani hospital, Sudan. Cases were women who had LBW deliveries ( 2,500 g) and controls were women with normal-weight babies ( 2.500 – 4,000 g). Sociodemographic and obstetrical characteristics were gathered from both groups and leptin and IGF-I levels were measured by ELISA. Cases and controls (45 in each arm) were matched in their basic data. The median (interquartile) of maternal leptin levels [9.9 (1.9 – 21.8) vs. 16.0 (9.6 – 20.8), ng/ml; P0.001] and IGF-I [1.6 (0.7 – 20.0) vs. 6.1 (4.3 – 7.1) ng/ml ; P 0.001] were significantly lower in cases than in controls. Likewise, cord serum leptin [5.8 (2.1 – 12.6) vs. 20.0 (5.1 – 37.8) ng/ml; P0.001] and cord serum IGF-I [1.7 (1.3 – 2.0) vs. 6.9 (5.9 – 7.4) ng/ml; P0.001] levels were significantly lower in cases than in controls. Significant positive correlation was found between birth weight and cord leptin ( r0.398), maternal ( r0.795) and cord ( r0.863) IGF-I levels. Maternal and cord leptin and IGF-I levels were significantly lower in LBW babies.

Expression of obesity gene and obesity gene long form receptor in endometrium of Yorkshire sows during embryo implantation

There is accumulating evidence that leptin may be directly involved in mammalian reproduction, however, the potential role of obesity gene/obesity gene long form receptor (ob/ob-Rb) system in porcine implantation is poorly understood. To further confirm this role, mRNA and protein expression of ob/ob-Rb in implantation site and inter-implantation sites of porcine uterus on pregnancy day 13, 18 and 24 were compared in this study. Ob mRNA level went up with the advance of pregnancy and was higher in implantation site than inter-implantation site (P < 0.05). But ob-Rb mRNA, which was negative-regulated by leptin, went down with the advance of pregnancy and lessened in implantation site compared with inter-implantation site (P < 0.05). During the three implantation phase, leptin protein peaked at day 18 pregnancy (P < 0.05) and leptin protein at implantation site were always higher than inter-implantation site (P < 0.05). The higher ob-Rb protein in implantation site compared with inter-implantation site (P < 0.05) only appeared at day 18 pregnancy. Localization of ob/ob-Rb protein in porcine uterus was assayed using immunohistochemistry and found that ob/ob-Rb protein mainly located in luminal epithelium and glandular epithelium in pregnant pigs, but distinct immune-staining of leptin also detected in stroma in non-pregnancy porcine uterus except for luminal epithelium and glandular epithelium. In conclusion, the peak of leptin and the peak of ob-Rb protein in implantation site specifically appeared on day 18 pregnancy of pig. Another funning discovery is ob-Rb mRNA in porcine endometrium was mainly negative-regulated by leptin. The space-time difference of gene and protein expression for ob/ob-Rb confirmed ob/ob-Rb system role as delicate regulator of porcine implantation process.

Maternal leptin, adiponectin, resistin, visfatin and tumor necrosis factor-alpha in normal and gestational diabetes

Gestational diabetes mellitus (GDM) is a common medical complication associated with pregnancy. The present study evaluates the changes in maternal adipocytokines (leptin, adiponectin, resistin, visfatin and tumor necrosis factor-alpha; TNF-α) in pregnancy complicated with GDM compared to normal pregnancy at 2nd and 3rd trimesters. The study included total number of 142 pregnant women classified into 4 groups: normal pregnancy (n = 33) and pregnancy with GDM (n = 24) both at 2nd trimester and normal pregnancy (n = 38) and GDM (n = 47) at 3rd trimester. Both GDM groups were significantly presented with elevated body mass index, fasting blood sugar and abnormal oral glucose tolerance test compared to their matched control. Results indicated reduction in maternal serum leptin and adiponectin in GDM compared to normal pregnancy at 3rd trimester. Elevated resistin and TNF-α were evident among pregnancy complicated with GDM at both tested trimesters. On the other hand, significant elevation in maternal visfatin was noted between GDM and matched control at 2nd trimester only. Significant increase in maternal leptin and visfatin and resistin was noted by advances in gestational period in healthy pregnancy. On the other hand, reduced adiponectin and elevated visfatin mean values were noticed in GDM at 3rd compared to 2nd trimester. It could be concluded that increased insulin resistance accompanies GDM is associated with suppressed leptin and adiponectin and increased resistin and TNF-α which might suggest their involvement in the development of GDM.

Reviews: adipocytokines in normal and complicated pregnancies

Human pregnancy is characterized by insulin resistance, traditionally attributed to the effects of placental hormones. Normal pregnancy-induced insulin resistance is further enhanced in pregnancy complications, associated with disturbed placental function, such as gestational diabetes mellitus, preeclampsia, and intrauterine growth restriction. Compelling evidence suggests that these pregnancy disorders are associated with future development of maternal metabolic syndrome. However, the pathogenetic mechanisms underlying the association between abnormal placental development, insulin resistance, and maternal metabolic syndrome are not fully understood. A large body of evidence has recently supported the role of adipose tissue in the regulation of insulin resistance in both nonpregnant and pregnant participants. In this respect, adipocytokines, which are adipocyte-derived hormones, have been implicated in the regulation of maternal metabolism and gestational insulin resistance. Adipocytokines, including leptin, adiponectin, tumor necrosis factor alpha, interleukin 6, as well as the newly discovered resistin, visfatin, and apelin, are also known to be produced within the intrauterine environment. However, data concerning the pattern of adipocytokines secretion in normal and complicated pregnancies are still limited and partially contradictory. Given the importance of adipose tissue and its hormones in terms of adequate metabolic control and energy homeostasis, we present a review of published data related to the role of adipocytokines in pregnancy, especially in relation to pregnancy complications. Focus will be placed on the functions and other potential roles of the novel adipocytokines resistin, visfatin, and apelin.

Effect of leptin on mouse trophoblast giant cells

Leptin plays a role in both energy homeostasis and reproduction, and it is required in early pregnancy. It stimulates metalloproteinase activity in cultured human trophoblasts and invasiveness of cultured mouse trophoblasts. Our goal has been to examine mechanisms that underpin the ability of leptin to promote trophoblast invasiveness in primary cultures of mouse trophoblasts. Leptin stimulated the phosphorylation of MEK (MAP2K1) but not signal transducer and activator of transcription 3 (STAT3) in the cultures, increased the concentration of the suppressor of cytokine signaling 3 (SOCS3) protein, and upregulated metalloproteinase activity. Microarray analysis revealed that leptin stimulated select genes with roles in cell motility, including Stmn, a gene linked to invasiveness in other cell types. There was also an increase in activity of several genes associated with MAPK and RhoGTPase signaling. In addition, leptin muted expression of genes correlated with terminal differentiation of trophoblast giant cells, including ones associated with the TGFbeta signaling pathway and endoreduplication of DNA, and upregulated selected prolactin-related family members. Feulgen staining of leptin-treated cells revealed a loss of cells with low ploidy. The data suggest that leptin accelerates disappearance of non-giant cells while inhibiting terminal differentiation of committed giant cells, possibly by maintaining cells in an intermediate stage of differentiation.

Severe preeclampsia-related changes in gene expression at the maternal-fetal interface include sialic acid-binding immunoglobulin-like lectin-6 and pappalysin-2

Preeclampsia (PE), which affects 4-8% of human pregnancies, causes significant maternal and neonatal morbidity and mortality. Within the basal plate, placental cytotrophoblasts (CTBs) of fetal origin invade the uterus and extensively remodel the maternal vasculature. In PE, CTB invasion is often shallow, and vascular remodeling is rudimentary. To better understand possible causes, we conducted a global analysis of gene expression at the maternal-fetal interface in placental samples from women with PE (n = 12; 24-36 wk) vs. samples from women who delivered due to preterm labor with no evidence of infection (n = 11; 24-36 wk), a condition that our previous work showed is associated with normal CTB invasion. Using the HG-U133A&B Affymetrix GeneChip platform, and statistical significance set at log odds-ratio of B >0, 55 genes were differentially expressed in PE. They encoded proteins previously associated with PE [e.g. Flt-1 (vascular endothelial growth factor receptor-1), leptin, CRH, and inhibin] and novel molecules [e.g. sialic acid binding Ig-like lectin 6 (Siglec-6), a potential leptin receptor, and pappalysin-2 (PAPP-A2), a protease that cleaves IGF-binding proteins]. We used quantitative PCR to validate the expression patterns of a subset of the genes. At the protein level, we confirmed PE-related changes in the expression of Siglec-6 and PAPP-A2, which localized to invasive CTBs and syncytiotrophoblasts. Notably, Siglec-6 placental expression is uniquely human, as is spontaneous PE. The functional significance of these novel observations may provide new insights into the pathogenesis of PE, and assaying the circulating levels of these proteins could have clinical utility for predicting and/or diagnosing PE.