Effect of the alcohol consumption on osteocyte cell processes: a molecular imaging study.

We have previously shown microarchitectural tissue changes with cellular modifications in osteocytes following high chronic alcohol dose. The aim of this study was to assess the dose effect of alcohol consumption on the cytoskeleton activity, the cellular lipid content and modulation of differentiation and apoptosis in osteocyte. Male Wistar rats were divided into three groups: Control (C), Alcohol 25% v/v (A25) or Alcohol 35% v/v (A35) for 17 weeks. Bone mineral density (BMD) was assessed by DXA, osteocyte empty lacunae, lacunae surface, bone marrow fat with bright field microscopy. Osteocyte lipid content was analysed with transmission electron microscopy (TEM) and epifluorescence microscopy. Osteocyte apoptosis was analysed with immunolabelling and TEM. Osteocyte differentiation and cytoskeleton activity were analysed with immunolabelling and real time quantitative PCR. At the end of the protocol, BMD was lower in A25 and A35 compared with C, while the bone marrow lipid content was increased in these groups. More empty osteocyte lacunae and osteocyte containing lipid droplets in A35 were found compared with C and A25. Cleaved caspase-3 staining and chromatin condensation were increased in A25 and A35 versus C. Cleaved caspase-3 was increased in A35 versus A25. CD44 and phosphopaxillin stainings were higher in A35 compared with C and A25. Paxillin mRNA expression was higher in A35 versus A25 and C and sclerostin mRNA expression was higher in A35 versus C. We only observed a dose effect of alcohol consumption on cleaved caspase-3 osteocyte immunostaining levels and on the number of lipid droplets in the bone marrow.

Adiponectin promotes syncytialisation of BeWo cell line and primary trophoblast cells.

BACKGROUND: In human pregnancy, a correct placentation depends on trophoblast proliferation, differentiation, migration and invasion. These processes are highly regulated by placental hormones, growth factors and cytokines. Recently, we have shown that adiponectin, an adipokine, has anti-proliferative effects on trophoblastic cells. Here, we complete this study by demonstrating that adiponectin modulates BeWo and human villous cytotrophoblast cell differentiation. RESULTS: We showed that hCG secretion was up-regulated by adiponectin treatment in both BeWo cells and human cytotrophoblasts from very early placentas (5-6 weeks). The expression of two trophoblast differentiation markers, leptin and syncytin 2, was also up-regulated by adiponectin in BeWo cells. Moreover, adiponectin treatment induced a loss of E-cadherin staining in these cells. In parallel, we demonstrated that AdipoR1 and AdipoR2 are up-regulated during forskolin induced BeWo cell differentiation, reinforcing the role of adiponectin in trophoblast syncytialization. SiRNA mediated down-regulation of AdipoR1 and AdipoR2 was used to demonstrate that adiponectin effects on differentiation were essentially mediated by these receptors. Finally, using a specific inhibitor, we demonstrated that the PKA signalling pathway could be one pathway involved in adiponectin effects on trophoblast differentiation. CONCLUSION: Adiponectin enhances the differentiation process of trophoblast cells and could thus be involved in functional syncytiotrophoblast formation.

Does Physical Exercise Always Improve Bone Quality in Rats?

For decades, the osteogenic effect from different physical activities on bone in rodents remained uncertain. This literature review presents for the first time the effects on five exercise models (treadmill running, wheel running, swimming, resistance training and vibration modes) in three different experimental rat groups (males, females, osteopenic) on bone quality. The bone parameters presented are bone mineral density, micro-architectural and mechanical properties, and osteoblast/osteocyte and osteoclast parameters. This review shows that physical activities have a positive effect (65% of the results) on bone status, but we clearly observed a difference amongst the different protocols. Even if treadmill running is the most used protocol, the resistance training constitutes the first exercise model in term of osteogenic effects (87% of the whole results obtained on this model). The less osteogenic model is the vibration mode procedure (31%). It clearly appears that the gender plays a role on the bone response to swimming and wheel running exercises. Besides, we did not observe negative results in the osteopenic population with impact training, wheel running and vibration activities. Moreover, about osteoblast/osteocyte parameters, we conclude that high impact and resistance exercise (such jumps and tower climbing) seems to increase bone formation more than running or aerobic exercise. Among the different protocols, literature has shown that the treadmill running procedure mainly induces osteogenic effects on the viability of the osteocyte lineage in both males and females or ovariectomized rats; running in voluntary wheels contributes to a negative effect on bone metabolism in older male models; whole-body vertical vibration is not an osteogenic exercise in female and ovariectomized rats; whereas swimming provides controversial results in female models. For osteoclast parameters only, running in a voluntary wheel for old males, the treadmill running program at high intensity in ovariectomized rats, and the swimming program in a specific ovariectomy condition have detrimental consequences.

Adiponectin mediates an antiproliferative response in human MDA-MB 231 breast cancer cells.

Numerous epidemiological studies have documented that obesity is a risk factor for breast cancer especially in post-menopausal women. However, the molecular basis of this association is not well known. In contrast to leptin, plasma levels of adiponectin, another major adipokine, are decreased in obese subjects. Therefore, we and others hypothesized that adiponectin may be a paracrine factor negatively controlling mammary tumor development. We recently demonstrated growth inhibition of the estrogen-sensitive breast cancer MCF-7 cell line by adiponectin. The purpose of the present study was to determine whether this anti-proliferative effect of adiponectin also applies to the MDA-MB 231 estrogen-insensitive breast epithelial cancer cell line. Our results demonstrate that i) the adiponectin-specific receptors AdipoR1 and R2 are expressed in these cells, and ii) the subphysiological concentrations of recombinant adiponectin inhibit MDA-MB 231 cell growth and concomitantly enhance the expression of Bax and p53, two pro-apoptotic genes. Moreover, the invalidation of AdipoR1 and R2 mRNA experiments demonstrated that the anti-proliferative and pro-apoptotic effects of adiponectin were partially mediated via AdipoR1 and R2. We describe, for the first time, that AdipoR mRNA expression was down-regulated by adiponectin and leptin in MDA-MB 231 cells. Taken altogether, these results strongly suggest that the two adipokines should be considered as i) additional factors of breast cancer risk, and ii) may therefore be potential targets in breast cancer therapy.

Synchrotron ultraviolet microspectroscopy on rat cortical bone: involvement of tyrosine and tryptophan in the osteocyte and its environment.

Alcohol induced osteoporosis is characterized by a bone mass decrease and microarchitecture alterations. Having observed an excess in osteocyte apoptosis, we aimed to assess the bone tissue biochemistry, particularly in the osteocyte and its environment. For this purpose, we used a model of alcohol induced osteoporosis in rats. Bone sections of cortical bone were investigated using synchrotron UV-microspectrofluorescence at subcellular resolution. We show that bone present three fluorescence peaks at 305, 333 and 385 nm, respectively corresponding to tyrosine, tryptophan and collagen. We have determined that tyrosine/collagen and tryptophan/collagen ratios were higher in the strong alcohol consumption group. Tryptophan is related to the serotonin metabolism involved in bone formation, while tyrosine is involved in the activity of tyrosine kinases and phosphatases in osteocytes. Our experiment represents the first combined synchrotron UV microspectroscopy analysis of bone tissue with a quantitative biochemical characterization in the osteocyte and surrounding matrix performed separately.

Antiproliferative and proapoptotic effects of bisphenol A on human trophoblastic JEG-3 cells.

Different studies performed in rodents revealed that bisphenol-A (BPA), an environmental compound, altered early embryonic development. However, little is known concerning the direct effects of BPA on human implantation process. Thus, we decided to study in vitro BPA's effects on proliferative capacities of the human trophoblastic cell line, JEG-3. For this purpose, we first have shown that JEG-3 cells express the specific BPA receptor, namely estrogen-related receptor γ1 (ERRγ1). Secondly, we demonstrated that BPA did not exert any cytotoxic action in JEG-3 cells up to 10(-6)M. Moreover [(3)H]-thymidine incorporation experiments revealed that BPA significantly reduced cell proliferation. The results also showed that BPA induced JEG-3 apoptosis capacity as reflected by DNA fragmentation experiments. In conclusion, we describe here the direct impact of BPA on trophoblastic cell number mediated through both anti-proliferative and pro-apoptotic effects.

Effects of adiponectin on human trophoblast invasion.

Adiponectin is an adipokine with insulin-sensitizing, anti-inflammatory, anti-atherogenic, and anti-proliferative effects. The expression of specific adiponectin receptors in the placenta and in the endometrium suggests a role for this cytokine in placental development, but this role has not yet been elucidated. The invasion of trophoblast cells during the first trimester of pregnancy being crucial to placentation process, we have studied adiponectin effects on human trophoblast invasive capacities. We found that adiponectin stimulated human trophoblast cell migration in HTR-8/SVneo cells in a dose-independent manner. In addition, adiponectin also significantly enhanced invasion of HTR-8/SVneo cells and of human extravillous trophoblast from first trimester placenta. These pro-invasive effects of adiponectin in human trophoblasts seem to be mediated in part via increased matrix metalloproteinases (MMP2 and MMP9) activities and via repression of TIMP2 mRNA expression. Our results suggest that adiponectin could be a positive regulator of the early invasion process by modulating the MMP/TIMP balance. Moreover, these results provide an insight into the role of adiponectin in pathological conditions characterized by insufficient or excessive trophoblast invasion.

Antiproliferative effects of adiponectin on human trophoblastic cell lines JEG-3 and BeWo.

During embryo implantation, a complex dialog exists between the mother and the fetus. However, little is known about the molecules that participate in this process. Among various factors secreted at the maternal-fetal interface, the adipose tissue-derived leptin is now considered a placental growth factor. Adiponectin is another adipocyte-derived signaling molecule known to exert antiproliferative effects in various cell types. In this work, we studied adiponectin sensitivity and effects on JEG-3 and BeWo choriocarcinoma cell lines. First, we showed that JEG-3 and BeWo cells express the specific adiponectin receptors ADIPOR1 and ADIPOR2 and respond to human recombinant adiponectin by AMP-activated protein kinase (PRKA, also known as AMPK) activation. Second, we demonstrated that adiponectin induces a reduction in cell number and in [(3)H]-thymidine incorporation, demonstrating that adiponectin has antiproliferative effects on trophoblastic cells. Furthermore, these effects of adiponectin seem to be, at least in part, mediated by the mitogen-activated protein kinase (MAPK) and phosphoinositide-3-kinase (PI3K) signaling pathways. We describe herein the direct effects of adiponectin in the control of trophoblastic cell proliferation.