Tianxia Xiao

Expression of Chemerin and Its Receptors in Rat Testes and Its Action on Testosterone Secretion

The novel adipokine chemerin plays a role in the regulation of lipid and carbohydrate metabolism, and recent reports of elevated chemerin levels in polycystic ovarian syndrome and preeclampsia have pointed to an emerging role of chemerin in reproduction. We hypothesised that chemerin, like other adipokines, may function to regulate male gonadal steroidogenesis. In this study, we show that chemerin and its three receptors chemokine-like receptor 1 (CMKLR1), G-protein-coupled receptor 1 (GPR1) and chemokine (C-C motif) receptor-like 2 were expressed in male reproductive tracts, liver and white adipose tissue. CMKLR1 and GPR1 proteins were localised specifically in the Leydig cells of human and rat testes by immunohistochemistry. The expression of chemerin and its receptors in rat testes was developmentally regulated and highly expressed in Leydig cells. In vitro treatment with chemerin suppressed the human chorionic gonadotropin (hCG)-induced testosterone production from primary Leydig cells, which was accompanied by the inhibition of 3β-hydroxysteroid dehydrogenase gene and protein expression. The hCG-activated p44/42 MAPK (Erk1/2) pathway in Leydig cells was also inhibited by chemerin cotreatment. Together, these data suggest that chemerin is a novel regulator of male gonadal steroidogenesis.

Chemerin-derived peptide C-20 suppressed gonadal steroidogenesis.

Chemerin is a novel chemo‐attractant and adipokine involved in leukocyte recruitment, inflammation, adipogenesis, lipid/carbohydrate metabolism, and reproduction. Based on the bioinformatic search for putative small peptides in the conserved region of pre‐pro‐chemerin, an evolutionary conserved region flanked by potential convertase cleavage sites was identified and we named it as C‐20. The binding capacity of C‐20 to chemerin receptors and its potential bioactivities were investigated in this study.

CMKLR1 deficiency maintains ovarian steroid production in mice treated chronically with dihydrotestosterone

Elevated serum chemerin levels correlate with increased severity of polycystic ovary syndrome (PCOS). However, the role of CMKLR1 signaling in ovarian biology under conditions of excess DHT remains unclear. In this study we compared the effects of continuous 90-day high dose DHT exposure (83.3 □g/day) on wild type and CMKLR1-deficient mice. DHT induced PCOS-like clinical signs in wild type mice as well as significant changes in the expression of hormone receptors, steroid synthesis enzymes, and BMPs and their receptors. In contrast, CMKLR1-deficient mice significantly attenuated DHT-induced clinical signs of PCOS and alterations in ovarian gene expression. To determine whether the BMP4 signaling pathway was involved in the pathogenic effects of CMKLR1 signaling in DHT-induced ovarian steroidogenesis, antral follicles were isolated from wild type and CMKLR1 knockout (KO) mice and treated in vitro with combinations of hCG, DHT, and BMP4 inhibitors. BMP4 inhibition attenuated the induction effects of hCG and DHT on estrogen and progesterone secretion in CMKLR1 KO mice, but not in WT mice, implicating the BMP4 signaling pathway in the CMKLR1-dependent response to DHT. In conclusion, CMKLR1 gene deletion attenuates the effects of chronic DHT treatment on ovarian function in experimental PCOS, likely via BMP4 signaling.

The role of GPR1 signaling in mice corpus luteum

Chemerin, a chemokine, plays important roles in immune responses, inflammation, adipogenesis, and carbohydrate metabolism. Our recent research has shown that chemerin has an inhibitory effect on hormone secretion from the testis and ovary. However, whether G protein-coupled receptor 1 (GPR1), the active receptor for chemerin, regulates steroidogenesis and luteolysis in the corpus luteum is still unknown. In this study, we established a pregnant mare serum gonadotropin-human chorionic gonadotropin (PMSG-hCG) superovulation model, a prostaglandin F2α (PGF2α) luteolysis model, and follicle and corpus luteum culture models to analyze the role of chemerin signaling through GPR1 in the synthesis and secretion of gonadal hormones during follicular/luteal development and luteolysis. Our results, for the first time, show that chemerin and GPR1 are both differentially expressed in the ovary over the course of the estrous cycle, with highest levels in estrus and metestrus. GPR1 has been localized to granulosa cells, cumulus cells, and the corpus luteum by immunohistochemistry (IHC). In vitro, we found that chemerin suppresses hCG-induced progesterone production in cultured follicle and corpus luteum and that this effect is attenuated significantly by anti-GPR1 MAB treatment. Furthermore, when the phosphoinositide 3-kinase (PI3K) pathway was blocked, the attenuating effect of GPR1 MAB was abrogated. Interestingly, PGF2α induces luteolysis through activation of caspase-3, leading to a reduction in progesterone secretion. Treatment with GPR1 MAB blocked the PGF2α effect on caspase-3 expression and progesterone secretion. This study indicates that chemerin/GPR1 signaling directly or indirectly regulates progesterone synthesis and secretion during the processes of follicular development, corpus luteum formation, and PGF2α-induced luteolysis.

Effects of icariin on the expression of ER, VEGF, and KDR in the endometrial cells of thin endometrium

We explored the effects of icariin on the expression of estrogen receptor (ER), vascular endothelial growth factor (VEGF), and kinase insert domain receptor (KDR) in the endometrial cells of the thin endometrium. Primary endometrial cells were obtained and divided into a blank control group, a high-, a middle-, and a low-dose icariin groups, as well as an estrogen treatment group to undergo cellular identification by immunocytochemistry. The expression levels of ER, VEGF, and its receptor were estimated by western blotting. The expression levels of ER, VEGF, and KDR gradually increased from the control group to the estrogen (E2) treatment and icariin treatment groups; the differences were statistically significant. However, the differences were not statistically significant among the different icariin dose groups. The endometrium may be thickened by icariin treatment by increasing the expression levels of ER, VEGF, and KDR in endometrial cells.

Targeted delivery of doxorubicin by CSA-binding nanoparticles for choriocarcinoma treatment

Abstract Gestational trophoblastic neoplasia (GTN) can result from the over-proliferation of trophoblasts. Treatment of choriocarcinoma, the most aggressive GTN, currently requires high doses of systemic chemotherapeutic agents, which result in indiscriminate drug distribution and severe toxicity. To overcome these disadvantages and enhance the chemotherapeutic efficacy, chondroitin sulfate A (CSA)-binding nanoparticles were developed for the targeted delivery of doxorubicin (DOX) to choriocarcinoma cells using a synthetic CSA-binding peptide (CSA-BP), derived from malarial protein, which specifically binds to the CSA exclusively expressed in the placental trophoblast. CSA-BP-conjugated nanoparticles rapidly bonded to choriocarcinoma (JEG3) cells and were efficiently internalized into the lysosomes. Moreover, CSA-BP modification significantly increased the anti-cancer activity of the DOX-loaded nanoparticles in vitro. Intravenous injections of CSA-BP-conjugated nanoparticles loaded with indocyanine green (CSA-INPs) were rapidly localized to the tumor. The CSA-targeted nanoparticles loaded with DOX (CSA-DNPs) strongly inhibited primary tumor growth and, more importantly, significantly suppressed metastasis in vivo. Collectively, our results highlight the potential of the CSA-BP-decorated nanoparticles as an alternative targeted delivery system of chemotherapeutic agents for treating choriocarcinoma and for developing new GTN therapies based on drug targeting.

PI3K, AKT, and P-AKT levels in thin endometrium.

The aim of this study was to explore the expression of PI3K, AKT, and P-AKT, and to investigate the role of PI3K/AKT signaling pathway in thin endometrium. We included 40 women treated in affiliated Shenzhen Nanshan Peoples Hospital of Guangdong Medical University for endometrial conditions between August 2013 and January 2015, 20 with a normal endometrium, and 20 with thin endometrium. The expression of PI3K, AKT, and P-AKT was evaluated by the immunohistochemical S-P method. The expression of PI3K, AKT, and P-AKT proteins was significantly lower in the thin endometrium group than in the normal endometrium group (P < 0.05). The expression of PI3K and AKT was positively correlated with the expression of P-AKT. The expression of PI3K, AKT, and P-AKT proteins in the thin endometrium decreases during the proliferative phase, and this process could be associated with PI3K/AKT signaling.

Placenta-specific drug delivery by trophoblast-targeted nanoparticles in mice

Rationale: The availability of therapeutics to treat pregnancy complications is severely lacking, mainly due to the risk of harm to the fetus. In placental malaria, Plasmodium falciparum-infected erythrocytes (IEs) accumulate in the placenta by adhering to chondroitin sulfate A (CSA) on the surfaces of trophoblasts. Based on this principle, we have developed a method for targeted delivery of payloads to the placenta using a synthetic placental CSA-binding peptide (plCSA-BP) derived from VAR2CSA, a CSA-binding protein expressed on IEs. Methods: A biotinylated plCSA-BP was used to examine the specificity of plCSA-BP binding to mouse and human placental tissue in tissue sections in vitro. Different nanoparticles, including plCSA-BP-conjugated nanoparticles loaded with indocyanine green (plCSA-INPs) or methotrexate (plCSA-MNPs), were administered intravenously to pregnant mice to test their efficiency at drug delivery to the placenta in vivo. The tissue distribution and localization of the plCSA-INPs were monitored in live animals using an IVIS imaging system. The effect of plCSA-MNPs on fetal and placental development and pregnancy outcome were examined using a small-animal high-frequency ultrasound (HFUS) imaging system, and the concentrations of methotrexate in fetal and placental tissues were measured using high-performance liquid chromatography (HPLC). Results: plCSA-BP binds specifically to trophoblasts and not to other cell types in the placenta or to CSA-expressing cells in other tissues. Moreover, we found that intravenously administered plCSA-INPs accumulate in the mouse placenta, and ex vivo analysis of the fetuses and placentas confirmed placenta-specific delivery of these nanoparticles. We also demonstrate successful delivery of methotrexate specifically to placental cells by plCSA-BP-conjugated nanoparticles, resulting in dramatic impairment of placental and fetal development. Importantly, plCSA-MNPs treatment had no apparent adverse effects on maternal tissues. Conclusion: These results demonstrate that plCSA-BP-guided nanoparticles could be used for the targeted delivery of payloads to the placenta and serve as a novel placenta-specific drug delivery option.

An experimental study on the use of icariin for improving thickness of thin endometrium

This study aimed to investigate the effect of icariin (ICA) on thin endometrium in a rat model. To this end, 6- to 8-week-old female Sprague Dawley rats (105) were randomly divided into 7 groups: untreated, vehicle-treated (lavage with NaCl), high-dose ICA (lavage with ICA at 200 mg∙kg-1∙day-1), medium-dose ICA (lavage ICA at 100 mg∙kg-1∙day-1), low-dose ICA (lavage with ICA at 50 mg∙kg-1∙day-1), sham model (injected with NaCl at uterus horn), and sample group. To induce thin endometrium, rats of all groups (except sham-model) were injected with 95% ethanol via the uterine horn. Each group underwent its respective treatment for 3 estrous cycles, after which 5 rats from each group were sacrificed, and endometrial thickness was measured. The expression of CD31, factor VIII, vascular endothelial growth factor (VEGF), cytokeratin (CK), and vimentin were detected via immunohistochemistry. The results showed that CD31, factor VIII, and VEGF were primarily expressed in the cytoplasm of endometrial and vascular epithelial cells. No difference in the expression of these factors was detected between the ICA lavage groups and the untreated groups. However, high dose ICA-treated group exhibited significantly higher expression of CD31, factor VIII, and VEGF compared to that in the low dose and vehicle-treated groups. CK and vimentin in the endometrial tissue were significantly higher in the untreated and treatment groups compared to the vehicle-treated group. This study demonstrated that ICA increases thickness of the endometrium, and it may modulate expression of VEGF, CD31, and factor VIII.