Jiunn-Ming Sheen

Effects of maternal l-citrulline supplementation on renal function and blood pressure in offspring exposed to maternal caloric restriction: The impact of nitric oxide pathway

Maternal undernutrition can cause reduced nephron number and glomerular hypertrophy, consequently leading to adult kidney disease. We intended to elucidate whether NO deficiency evolves to kidney disease vulnerability in offspring from mothers with caloric restriction diets and whether maternal L-citrulline (L-Cit) supplementation can prevent this. Using a rat model with 50% caloric restriction, four groups of 3-month-old male offspring were sacrificed to determine their renal outcome: control, caloric restriction (CR), control treated with 0.25% L-citrulline solution during the whole period of pregnancy and lactation (Cit), and CR treated in the same way (CR+Cit group). The CR group had low nephron numbers, increased glomerular diameter, and an increased plasma creatinine level compared with the control group. Maternal L-Cit supplementation prevented these effects. The CR+Cit and Cit groups developed hypertension beginning at 4 and 8weeks of age, respectively. Plasma asymmetric and symmetric dimethylarginine (ADMA and SDMA) levels were increased, but L-arginine/ADMA ratios (AAR) were decreased in the CR group vs the control group. This was prevented by maternal L-Cit supplementation. Renal cortical neuronal NOS-alpha (nNOSalpha) protein abundance was significantly decreased in the Cit and CR+Cit groups. Collectively, reduced nephron number, reduced renal nNOSalpha expression, increased ADMA, and decreased AAR contribute to the developmental programming of adult kidney disease and hypertension. Although maternal L-Cit supplementation prevents caloric restriction-induced low nephron number and renal dysfunction, it also induces hypertension.

Melatonin blocks oxidative stress-induced increased asymmetric dimethylarginine

Asymmetric dimethylarginine (ADMA) is a competitive inhibitor of nitric oxide synthase, and its increase is associated with many systemic diseases. We recently found that increases in plasma and hepatic ADMA levels were associated with oxidative stress in young bile-duct-ligation (BDL) rats; these increases were prevented by melatonin therapy. Therefore, we used an in vivo BDL model and in vitro cultured hepatocytes to elucidate the protective mechanisms of melatonin against oxidative stress-induced increase in ADMA. We found that the presence of reactive oxygen species (ROS) in young rats with BDL leads to downregulation of dimethylarginine dimethyaminohydrolase (DDAH)-1 and -2 as well as DDAH activity. Melatonin prevented ADMA increases in the liver mainly by regulating DDAH-1 and -2. The expression and activity of DDAH were suppressed in vitro by superoxide and hydrogen peroxide (H(2)O(2)) in a time-dependent manner, whereas melatonin could block H(2)O(2)-induced downregulation of DDAH-2 as well as decreased DDAH activity, thereby preventing increases in hepatic ADMA. Our findings reveal a mechanistic basis of DDAH downregulation by ROS and suggest that melatonin might be a potential therapy for various diseases with elevated cellular ADMA.

A unique plasma proteomic profiling with imbalanced fibrinogen cascade in patients with Kawasaki disease.

Kawasaki disease (KD) is the leading cause of acquired heart disease during childhood in the developed countries. The mechanism and biomarkers of KD remain to be determined. In this study, we sought to elucidate potential plasma proteomic markers in KD patients in comparison to that in febrile controls. Plasma samples from KD patients and febrile controls were subjected to two‐dimensional polyacrylamide gel electrophoresis analysis. Differential protein displays between KD patients and febrile controls were determined. Fibrinogen beta and gamma chains, alpha‐1‐antitrypsin (A1AT), CD5 antigen‐like precursor (CD5L), and clusterin were increased in KD patients, whereas immunoglobulin free light chains were decreased, as compared with controls. The differential protein displays were validated with enzyme‐linked immunosorbent assay tests. We found higher fibrinogen‐related proteins (fibrinogen, A1AT, clusterin, and CD5L), along with a lower level of the immunoglobulin free light chains that involve fibrin degradation in KD. Results from this study showing a unique proteomic profiling with abnormal fibrinogen cascade may afford a good biomarker of KD and a better strategy to prevent cardiovascular complications of KD by correcting abnormal fibrin deposition or degradation.

Melatonin utility in neonates and children

Melatonin (N-acetyl-5-methoxytryptamine) is an endogenously produced indoleamine secreted by the pineal gland and the secretion is suppressed by light. Melatonin is a highly effective antioxidant, free radical scavenger, and has anti-inflammatory effect. Plenty of evidence supports the utility of melatonin in adults for cancer, neurodegenerative disorders, and aging. In children and neonates, melatonin has been used widely, including for respiratory distress syndrome, bronchopulmonary dysplasia, periventricular leukomalacia (PVL), hypoxia-ischemia encephalopathy and sepsis. In addition, melatonin can be used in childhood sleep and seizure disorders, and in neonates and children receiving surgery. This review article discusses the utility of melatonin in neonates and children.

Roles of Melatonin in Fetal Programming in Compromised Pregnancies

Compromised pregnancies such as those associated with gestational diabetes mellitus, intrauterine growth retardation, preeclampsia, maternal undernutrition, and maternal stress may negatively affect fetal development. Such pregnancies may induce oxidative stress to the fetus and alter fetal development through the epigenetic process that may affect development at a later stage. Melatonin is an oxidant scavenger that reverses oxidative stress during the prenatal period. Moreover, the role of melatonin in epigenetic modifications in the field of developmental programming has been studied extensively. Here, we describe the physiological function of melatonin in pregnancy and discuss the roles of melatonin in fetal programming in compromised pregnancies, focusing on its involvement in redox and epigenetic mechanisms.

Proteomic analysis of the effects of baicalein on colorectal cancer cells.

Baicalein is the flavonoids with multiple pharmacological activities. The aim of our study was to investigate the effects of baicalein on colorectal cancer (CRC) and to recognize the targets of baicalein treatment. To better understand baicaleins target, proteomic approaches were used to purify and identify the protein substrates using 2D difference gel electrophoresis (2D SDS‐PAGE) to elucidate proteins differential display. Results from this study investigate that baicalein treatment of CRC cells results in reduced cell proliferation. As a result, differential protein displays between baicalein‐treated and untreated CRC were determined and validated. There were 11 differentially expressed proteins between baicalein‐treated and untreated CRC. Furthermore, we demonstrate that baicalein inhibits cancer cell proliferation and reduced reactive oxygen species (ROS) by up‐regulating the levels of peroxiredoxin‐6 (PRDX6). Knockdown of PRDX6 in baicalein‐treated CRC cells by specific small interfering RNA resulted in ROS production and proliferation, opposite of the baicalein treatment scenario as indicated by cell cycle distribution. These results illustrate that baicalein up‐regulates the expression of PRDX6, which attenuates the generation of ROS and inhibits the growth of CRC cells, whereas baicalein treatment have no effect on normal epithelial cells.

Maternal citrulline supplementation prevents prenatal dexamethasone-induced programmed hypertension.

Abstract Glucocorticoids are administered to premature infants to accelerate pulmonary maturation. In experimental model, prenatal dexamethasone (DEX) results in reduced nephron number and adulthood hypertension. Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase (NOS), can cause oxidative stress and is involved in the development of hypertension. l-citrulline can be converted to l-arginine (the substrate for NOS) in the body. Thus we intended to determine if maternal l-citrulline therapy can prevent prenatal DEX-induced programmed hypertension by restoration ADMA/nitric oxide (NO) balance, alterations of renin–angiotensin system (RAS) and sodium transporters, and epigenetic regulation by histone deacetylases (HDACs). Male offspring were assigned to four groups: control, pregnancy rats received intraperitoneal DEX (0.2mg/kg body weight) daily on gestational days 15 and 16 (DEX), pregnancy rats received 0.25% l-citrulline in drinking water during the entire pregnancy and lactation period (CIT), and DEX + CIT. We found DEX group developed hypertension at 16 weeks of age, which was prevented by maternal l-citrulline therapy. Prenatal DEX exposure increased plasma ADMA concentrations and reduced renal NO production. However, l-citrulline reduced plasma ADMA level and increased renal level of NO in DEX + CIT group. Next, prenatal DEX-induced programmed hypertension is related to increased mRNA expression of angiotensin and angiotensin II type 1 receptor, and class I HDACs in the kidney. Prenatal DEX exposure increased renal protein abundance of Na+/Cl− cotransporter (NCC), which was prevented by l-citrulline therapy. The beneficial effects of l-citrulline therapy include restoration of ADMA/NO balance and alteration of NCC, to prevent the prenatal DEX-induced programmed hypertension.

Melatonin prevents increased asymmetric dimethylarginine in young rats with bile duct ligation

Abstract:  Identifying and treating kidney injury in cirrhosis is important. Bile duct ligation (BDL) is a commonly used cholestatic liver disease model. We hypothesized that asymmetric dimethylarginine (ADMA) is involved in BDL‐induced oxidative stress and kidney injury, which can be prevented by melatonin. We also intended to elucidate whether increased ADMA is due to increased protein arginine methyltransferase‐1 (PRMT1, ADMA‐synthesizing enzyme) and/or decreased dimethylarginine dimethylaminohydrolase (DDAH, ADMA‐metabolizing enzyme). Three groups of young rats were studied, sham (N = 7), untreated BDL rats (N = 9), and melatonin‐treated BDL rats (N = 6, BDL + M). Melatonin‐treated BDL rats received daily melatonin 1 mg/kg/day via intraperitoneal injection. One‐third of the young BDL rats died compared with none in the BDL + M group. All surviving rats were killed 14 days after surgery. BDL rats had higher plasma aspartate aminotransferase, alanine aminotransferase, direct and total bilirubin, and ammonia levels than shams. They also had kidney injury characterized by increased tubulointerstitial injury scores and plasma creatinine and symmetric dimethylarginine levels, which melatonin prevented. Plasma ADMA levels were elevated in BDL rats, combined with increased hepatic PRMT1 and decreased renal DDAH activity. In addition, melatonin increased hepatic DDAH2 expression, increased DDAH activity and concomitantly decreased ADMA contents in both the liver and kidney. In conclusion, melatonin therapy decreased mortality and prevented kidney injury induced by BDL via reduction of ADMA (by increasing DDAH activity) and oxidative stress.

The interaction between high ammonia diet and bile duct ligation in developing rats: assessment by spatial memory and asymmetric dimethylarginine

Bile duct ligation (BDL) in developing rats causes cholestasis, impaired liver function and cognition. Because both nitric oxide (NO) and ammonia are implicated in hepatic encephalopathy (HE), we hypothesized that asymmetric dimethylarginine (ADMA), an endogenous NO synthase inhibitor, and ammonia affect cognition in young rats with BDL. Four groups of young male Sprague–Dawley rats ages 17 days were used: rat underwent laparotomy (SC group), rat underwent laparotomy plus a 30% ammonium acetate diet (SC + HA group), rat underwent BDL (BDL group), rats underwent BDL plus high ammonia diet (BDL + HA group). Spatial memory was assessed by Morris water maze task. Plasma was collected for biochemical and ADMA analyses. Liver and brain cortex were collected for determination of protein arginine methyltransferase‐1 (PRMT1, ADMA‐synthesizing enzyme) and dimethylarginine dimethylaminohydrolase (DDAH, ADMA‐metabolizing enzyme). We found BDL group had significantly higher plasma direct/total bilirubin, aspartate aminotransferase, alanine aminotransferase, ADMA, liver p22phox, and worse spatial performance as compared with SC group. High ammonia diet increased plasma ammonia and ADMA concentration, and aggravated spatial deficit in the presence of BDL‐induced cholestasis. We conclude plasma ADMA plays a role in BDL‐induced spatial deficit. High ammonia aggravated the spatial deficits encountered in cholestatic young rats.

IFN-α production by human mononuclear cells infected with varicella-zoster virus through TLR9-dependent and -independent pathways

Understanding the defense mechanisms of the host of an organism is important for infection control. In previous studies, we demonstrated that interferon-α (IFN-α), but not IL-12, was produced by human peripheral blood mononuclear cells infected with varicella-zoster virus (VZV). Here, we investigated what kind of cell(s) and which signal molecule(s) are involved in IFN-α production. Using cell isolation and ELISA, we found that plasmacytoid dendritic cells (pDCs) were responsible for IFN-α production during VZV infection. We also found that Toll-like receptor 9 (TLR9) was involved in VZV-induced IFN-α production because inhibitory CpG oligodeoxynucleotide inhibited IFN-α production. UV-inactivated VZV-induced IFN-α production was lower than that of active VZV, indicating another TLR9-independent pathway. Further studies demonstrated that double-stranded RNA-dependent protein kinase, but not DNA-dependent protein kinase was involved in VZV-induced IFN-α production. Together, these results suggest that pDCs play an important role in IFN-α production during VZV infection through TLR9-dependent and -independent pathways.