Linlong Wang

Intrauterine metabolic programming alteration increased susceptibility to non-alcoholic adult fatty liver disease in prenatal caffeine-exposed rat offspring.

An increase in susceptibility to metabolic syndromes (MetS) in rat offspring that experienced prenatal caffeine exposure (PCE) has been previously demonstrated. The present study aimed to clarify this increased susceptibility and elucidate the mechanism of foetal origin that causes or contributes to adult non-alcoholic fatty liver disease (NAFLD) as a result of PCE. Based on the results from both foetal and adult studies of rats that experienced PCE (120 mg/kgd), the foetal weight and serum triglyceride levels decreased significantly and hepatocellular ultrastructure was altered. Foetal livers exhibited inhibited insulin-like growth factor-1 (IGF-1), enhanced lipogenesis and reduced lipid output. In adult female offspring of PCE+lab chow, lipid synthesis, oxidation and output were enhanced, whereas lipogenesis was inhibited in their male conterparters. Furthermore, in adult offspring of PCE+ high-fat diet, catch-up growth appeared obvious with enhanced hepatic IGF-1, especially in females. Both males and females showed increased lipid synthesis and reduced output, which were accompanied by elevated serum triglyceride. Severe NAFLD appeared with higher Kleiner scores. Gluconeogenesis was continuously enhanced in females. Therefore, increased susceptibility to diet-induced NAFLD in PCE offspring was confirmed, and it appears to be mediated by intrauterine glucose and alterations in lipid metabolic programming. This altered programming enhanced foetal hepatic lipogenesis and reduced lipid output in utero, which continued into the postnatal phase and reappeared in adulthood with the introduction of a high-fat diet, thereby aggravating hepatic lipid accumulation and causing NAFLD.

Low functional programming of renal AT2R mediates the developmental origin of glomerulosclerosis in adult offspring induced by prenatal caffeine exposure.

Our previous study has indicated that prenatal caffeine exposure (PCE) could induce intrauterine growth retardation (IUGR) of offspring. Recent research suggested that IUGR is a risk factor for glomerulosclerosis. However, whether PCE could induce glomerulosclerosis and its underlying mechanisms remain unknown. This study aimed to demonstrate the induction to glomerulosclerosis in adult offspring by PCE and its intrauterine programming mechanisms. A rat model of IUGR was established by PCE, male fetuses and adult offspring at the age of postnatal week 24 were euthanized. The results revealed that the adult offspring kidneys in the PCE group exhibited glomerulosclerosis as well as interstitial fibrosis, accompanied by elevated levels of serum creatinine and urine protein. Renal angiotensin II receptor type 2 (AT2R) gene expression in adult offspring was reduced by PCE, whereas the renal angiotensin II receptor type 1a (AT1aR)/AT2R expression ratio was increased. The fetal kidneys in the PCE group displayed an enlarged Bowmans space and a shrunken glomerular tuft, accompanied by a reduced cortex width and an increase in the nephrogenic zone/cortical zone ratio. Observation by electronic microscope revealed structural damage of podocytes; the reduced expression level of podocyte marker genes, nephrin and podocin, was also detected by q-PCR. Moreover, AT2R gene and protein expressions in fetal kidneys were inhibited by PCE, associated with the repression of the gene expression of glial-cell-line-derived neurotrophic factor (GDNF)/tyrosine kinase receptor (c-Ret) signaling pathway. These results demonstrated that PCE could induce dysplasia of fetal kidneys as well as glomerulosclerosis of adult offspring, and the low functional programming of renal AT2R might mediate the developmental origin of adult glomerulosclerosis.

Increased DNA methylation of scavenger receptor class B type I contributes to inhibitory effects of prenatal caffeine ingestion on cholesterol uptake and steroidogenesis in fetal adrenals

Steroid hormones synthesized from cholesterol in the fetal adrenal are crucial for fetal development. We have observed the inhibited fetal adrenal corticosterone synthesis and increased intrauterine growth retardation (IUGR) rate in rats under prenatal caffeine ingestion. The aim of this study is to evaluate the effects of prenatal caffeine ingestion on cholesterol supply in fetal adrenal steroidogenesis in rats and explore the underlying epigenetic mechanisms. Pregnant Wistar rats were treated with 60 mg/kg · d caffeine from gestational day (GD) 7 to GD17. Histological changes of fetal adrenals and increased IUGR rates were observed in the caffeine group. There were significantly decreased steroid hormone contents and cholesterol supply in caffeine-treated fetal adrenals. Data from the gene expression array suggested that prenatal caffeine ingestion caused increased expression of genes related to DNA methylation and decreased expression of genes related to cholesterol uptake. The following conjoint analysis of DNA methylation array with these differentially expressed genes suggested that scavenger receptor class B type I (SR-BI) may play an important role in caffeine-induced cholesterol supply deficiency. Moreover, real-time RT-PCR and immunohistochemical detection certified the inhibitory effects of caffeine on both mRNA expression and protein expression of SR-BI in the fetal adrenal. And the increased DNA methylation frequency in the proximal promoter of SR-BI was confirmed by bisulfite-sequencing PCR. In conclusion, prenatal caffeine ingestion can induce DNA hypermethylation of the SR-BI promoter in the rat fetal adrenal. These effects may lead to decreased SR-BI expression and cholesterol uptake, which inhibits steroidogenesis in the fetal adrenal.

Angelica Sinensis Polysaccharides Stimulated UDP-Sugar Synthase Genes through Promoting Gene Expression of IGF-1 and IGF1R in Chondrocytes: Promoting Anti-Osteoarthritic Activity

Background Osteoarthritis (OA) is a chronic joints disease characterized by progressive degeneration of articular cartilage due to the loss of cartilage matrix. Previously, we found, for the first time, that an acidic glycan from Angelica Sinensis Polysaccharides (APSs), namely the APS-3c, could protect rat cartilage from OA due to promoting glycosaminoglycan (GAG) synthesis in chondrocytes. In the present work, we tried to further the understanding of ASP-3c’s anti-OA activity. Methodology/Principal Findings Human primary chondrocytes were treated with APS-3c or/and recombinant human interleukin 1β (IL-1β). It turned out that APS-3c promoted synthesis of UDP-xylose and GAG, as well as the gene expression of UDP-sugar synthases (USSs), insulin like growth factor 1 (IGF1) and IGF1 receptor (IGF1R), and attenuated the degenerative phenotypes, suppressed biosynthesis of UDP-sugars and GAG, and inhibited the gene expression of USSs, IGF1 and IGF1R induced by IL-1β. Then, we induced a rat OA model with papain, and found that APS-3c also stimulated GAG synthesis and gene expression of USSs, IGF1 and IGF1R in vivo. Additionally, recombinant human IGF1 and IGF1R inhibitor NP-AEW541 were applied to figure out the correlation between stimulated gene expression of USSs, IGF1 and IGF1R induced by APS-3c. It tuned out that the promoted GAG synthesis and USSs gene expression induced by APS-3c was mediated by the stimulated IGF1 and IGF1R gene expression, but not through directly activation of IGF1R signaling pathway. Conclusions/Significances We demonstrated for the first time that APS-3c presented anti-OA activity through stimulating IGF-1 and IGF1R gene expression, but not directly activating the IGF1R signaling pathway, which consequently promoted UDP-sugars and GAG synthesis due to up-regulating gene expression of USSs. Our findings presented a better understanding of APS-3c’s anti-OA activity and suggested that APS-3c could potentially be a novel therapeutic agent for OA.

Mitogen‐inducible gene‐6 partly mediates the inhibitory effects of prenatal dexamethasone exposure on endochondral ossification in long bones of fetal rats

Prenatal exposure to dexamethasone slows down fetal linear growth and bone mineralization but the regulatory mechanism remains unknown. Here we assessed how dexamethasone regulates bone development in the fetus.

Cytotoxic effects of the quinolone levofloxacin on rabbit meniscus cells

Quinolones have been reported to induce adverse effects on articular cartilage, tendons and ligaments. However, the effects of quinolones on menisci have not been revealed. The present study was to test the effects of levofloxacin on meniscus cells in vitro. Rabbit meniscus cells were administrated with different concentrations of levofloxacin (0, 14, 28, 56, 112 and 224 µm) for 24 or 48 h, and cell viability and apoptosis were measured. The mRNA expression levels of matrix metalloproteinase (MMP)‐1, MMP‐3, MMP‐13, tissue inhibitors of metalloproteinase (TIMP)‐1, TIMP‐3, Col1a1, Bcl‐2, caspase‐3 and inducible nitric oxide were analyzed by real‐time polymerase chain reaction. Active caspase‐3 was detected by immunocytochemical assay, while protein expression levels of MMP‐3 and MMP‐13 were measured by Western blotting assay. After treatment with levofloxacin for 48 h, cell viability was decreased from dose of 28 to 224 µm in a concentration‐dependent manner. An increase of apoptotic cells was observed by flow cytometry. Active caspase‐3 protein expression level was also increased. The mRNA level of Bcl‐2 was decreased and levels of MMP‐1, MMP‐3 and MMP‐13 in experimental groups were higher than those of controls. The protein levels of MMP‐3 and MMP‐13 were increased. Moreover, the mRNA levels of TIMP‐3 and col1a1 were decreased. A dose‐dependent increase of inducible nitric oxide mRNA expression level was also observed. Our results suggested the cytotoxic effects of levofloxacin on meniscus cells through induction of apoptosis and unbalanced MMPs/TIMPs expression. These side effects might result in meniscus extracellular matrix degradation and meniscal lesion. Thus, quinolones should be used cautiously on patients who perform athletic activities or undergo surgical meniscus repair. Copyright

Prenatal nicotine exposure-induced intrauterine programming alteration increases the susceptibility of high-fat diet-induced non-alcoholic simple fatty liver in female adult offspring rats

Previous studies have indicated that the intrauterine growth retardation (IUGR) fetus is faced with a high susceptibility to adult metabolic syndrome (MS). Non-alcoholic simple fatty liver (NAFL) is considered to be the hepatic manifestation of MS. In the present study, we evaluated the susceptibility of high-fat diet-induced NAFL in female adult IUGR offspring rats, induced by prenatal nicotine exposure, and we further explored the underlying intrauterine programming mechanism for this phenomenon. The IUGR rat model was established by prenatal exposure to nicotine (2 mg kg−1 d−1), the liver tissues from female fetuses and female adult offspring fed with normal or high-fat diets were collected. The female adult offspring in the nicotine-exposed group showed low birth weights and postnatal catch-up growth, as well as severe NAFL under high-fat diets. Moreover, increased gene expression involved in the hepatic insulin-like growth factor 1 (IGF1) pathway, gluconeogenesis and lipid synthesis, and decreased gene expression of lipid output accompanied with elevated serum triglyceride levels, was observed. The female fetuses in the nicotine-exposed group showed down-regulated hepatic IGF1 pathways, and also exhibited similar patterns of increased gluconeogenesis, lipid synthesis and decreased lipid output to those in the adults. The present study demonstrates the intrauterine origin of increased susceptibility to high-fat diet-induced NAFL in female offspring rats by prenatal nicotine exposure, which is most likely mediated by “two intrauterine programming”. That is, the first glucocorticoid-IGF1 axis programming induces postnatal catch-up growth, aggravates glucose and lipid metabolic disorders, and leads to an increased susceptibility to adult NAFL, while the second hepatic glucose and lipid metabolic programming enhances hepatic lipogenesis and reduces lipid oxidation and output, promoting NAFL.

Prenatal ethanol exposure induces the osteoarthritis-like phenotype in female adult offspring rats with a post-weaning high-fat diet and its intrauterine programming mechanisms of cholesterol metabolism

Osteoarthritis (OA) development is associated with hypercholesterolemia in adults. Our previous study demonstrated that offspring with intrauterine growth retardation (IUGR) due to prenatal ethanol exposure (PEE) had a high risk of developing hypercholesterolemia and metabolic syndrome when fed a post-weaning high-fat diet (HFD). In this study, we examined the changes in articular chondrocytes of IUGR offspring induced by PEE and explored its intrauterine programming mechanisms related to cholesterol metabolism. Using the PEE/IUGR model, serum and tibias from female fetuses and adult female offspring fed a post-weaning HFD were collected and examined for cholesterol metabolism and histology. The results showed that PEE adult offspring manifested significant catch-up growth. Their serum total cholesterol (TCH) and low-density lipoprotein-cholesterol increased and high-density lipoprotein-cholesterol decreased; the osteoarthritis-like phenotype and an increased TCH content were observed in articular cartilage; and the expression of insulin-like growth factor1 (IGF1) and cholesterol efflux pathway, including ATP-binding-cassette transporter A1 and liver X receptor, was reduced. The expression of IGF1 and cholesterol efflux pathway was also lower in the PEE fetuses. This study showed PEE could induce an enhanced susceptibility to HFD-induced OA in adult female IUGR offspring. The underlying mechanism related to cholesterol accumulation in cartilage mediated by intrauterine programming.

Mig6 partially mediates the inhibitory effects of prenatal dexamethasone exposure on endochondral ossification in long bone of foetal rat

Prenatal exposure to dexamethasone slows down fetal linear growth and bone mineralization but the regulatory mechanism remains unknown. Here we assessed how dexamethasone regulates bone development in the fetus.

UDP-glucose dehydrogenase modulates proteoglycan synthesis in articular chondrocytes: its possible involvement and regulation in osteoarthritis

IntroductionThe objective of this study was to investigate the possible role of UDP-glucose dehydrogenase (UGDH) in osteoarthritis (OA) and uncover whether, furthermore how interleukin-1beta (IL-1β) affects UGDH gene expression.MethodsUGDH specific siRNAs were applied to determine the role of UGDH in proteoglycan (PG) synthesis in human articular chondrocytes. Protein levels of UGDH and Sp1 in human and rat OA cartilage were detected. Then, human primary chondrocytes were treated with IL-1β to find out whether and how IL-1β could regulate the gene expression of UGDH and its trans-regulators, that is Sp1, Sp3 and c-Krox. Finally, p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 and stress-activated protein kinase/c-Jun N-terminal kinase (SAP/JNK) inhibitor SP600125 were used to pick out the pathway that mediated the IL-1β-modulated PGs synthesis and gene expression of UGDH, Sp1, Sp3 and c-Krox.ResultsUGDH specific siRNAs markedly inhibited UGDH mRNA and protein expression, and thus led to an obvious suppression of PGs synthesis in human articular chondrocytes. UGDH protein level in human and rat OA cartilage were much lower than the corresponding controls and negatively correlated to the degree of OA. Decrease in Sp1 protein level was also observed in human and rat OA cartilage respectively. Meanwhile, IL-1β suppressed UGDH gene expression in human articular chondrocytes in the late phase, which also modulated gene expression of Sp1, Sp3 and c-Krox and increased both Sp3/Sp1 and c-Krox/Sp1 ratio. Moreover, the inhibition of SAP/JNK and p38 MAPK pathways both resulted in an obvious attenuation of the IL-1β-induced suppression on the UGDH gene expression.ConclusionsUGDH is essential in the PGs synthesis of articular chondrocytes, while the suppressed expression of UGDH might probably be involved in advanced OA, partly due to the modulation of p38 MAPK and SAP/JNK pathways and its trans-regulators by IL-1β.