The effect of mycophenolate mofetil on podocytes in nephrotoxic serum nephritis.

Mycophenolate mofetil (MMF) is applied in proteinuric kidney diseases, but the exact mechanism of its effect on podocytes is still unknown. Our previous in vitro experiments suggested that MMF can ameliorate podocyte damage via restoration of the Ca2+-actin cytoskeleton axis. The goal of this study was to characterize podocyte biology during MMF treatment in nephrotoxic serum (NTS) nephritis (NTN). NTN was induced in three-week old wild-type mice. On day 3, half of the mice were treated with MMF (100 mg/kgBW/d p.o.) for one week. On day 10, we performed proteomic analysis of glomeruli as well as super-resolution imaging of the slit diaphragm. For multiphoton imaging of Ca2+ concentration ([Ca2+]i), the experimental design was repeated in mice expressing podocyte-specific Ca2+ sensor. MMF ameliorated the proteinuria and crescent formation induced by NTS. We identified significant changes in the abundance of proteins involved in Ca2+ signaling and actin cytoskeleton regulation, which was further confirmed by direct [Ca2+]i imaging in podocytes showing decreased Ca2+ levels after MMF treatment. This was associated with a tendency to restoration of podocyte foot process structure. Here, we provide evidence that MPA has a substantial direct effect on podocytes. MMF contributes to improvement of [Ca2+]i and amelioration of the disorganized actin cytoskeleton in podocytes. These data extend the knowledge of direct effects of immunosuppressants on podocytes that may contribute to a more effective treatment of proteinuric glomerulopathies with the least possible side effects.

Strong hypoxia reduces leptin synthesis in purified primary human trophoblasts.

INTRODUCTION: Oxygen availability severely affects placental function. During placental hypoxia, stabilization of hypoxia inducible factors (HIFs) affects transcription, and leptin gene expression concomitantly increases in vivo and in vitro. However, a causal relationship is uncertain. METHODS: We investigated the effect of oxygen availability on HIF-1 alpha (HIF1A) and leptin regulation in primary human trophoblasts isolated from six normal term placentae cultured at 0.1%, 1%, 3%, and 8% oxygen for 6 h, 24 h and 48 h. Gene expressions of leptin (LEP), leptin receptors (LEPR), HIF1A, insulin receptor (INSR) and further genes relevant in hypoxia (VEGFA, EPO, NOS2) or apoptosis (BCL2, BAX, Tp53) were examined. Leptin, HIF1A, INSR, phospho-AKT/AKT (insulin receptor signaling), caspase 3 and cleaved caspase 3 (apoptosis) proteins were measured. RESULTS: A hypoxic reaction with stabilization of HIF1A protein as well as up-regulation of HIF1A and VEGFA gene expressions, but without any hint for apoptosis, was present at 0.1% and 1% oxygen. However, leptin protein concentration (cell supernatants) peaked at 8% oxygen (normoxia) and was significantly reduced at 0.1% oxygen. There was no significant correlation between leptin and HIF1A, neither on the gene nor on the protein level. DISCUSSION: Elevated leptin gene expression in hypoxic placentas may not originate from trophoblasts, but from other placental cells, or from interaction of trophoblasts with other cells. Not only fetal hyperleptinemia, but also fetal hypoleptinemia under hypoxic conditions is conceivable. Strategies to prevent leptin dysregulation during pregnancy should be elucidated to protect the offspring from fetal programming of leptin resistance and adiposity in later life.

Leptin and neuropeptide Y gene expression in human placenta: ontogeny and evidence for similarities to hypothalamic regulation.

The objective of the present study was to examine the impact of preeclampsia on the relation of leptin and neuropeptide Y (NPY) gene expression in human placenta. A second goal was to monitor the change of leptin messenger RNA (mRNA) with increasing gestational age. Placental tissue was obtained from 17 premature deliveries, 18 term deliveries, and 10 mothers with preeclampsia. Gene expression of leptin, NPY, and two housekeeping genes (beta-actin and glyceraldehyde-3-phosphate dehydrogenase was quantified using real-time PCR. The leptin/beta-actin mRNA ratio was significantly higher in specimens of patients with preeclampsia than in those of gestational age-matched controls (0.63+/-0.23 vs. 0.09+/-0.04 relative U (RU); P = 0.03). NPY/beta-actin mRNA was significantly reduced in the preeclampsia group (0.003+/-0.001 vs. 0.026+/-0.008 RU in controls; P = 0.01). The NPY/leptin ratio was 0.11+/-0.09 for preeclamptic placenta samples and 1.7+/-0.6 RU for the controls (P = 0.02). The leptin/beta-actin ratio was significantly lower in placenta from premature deliveries than in term deliveries (0.02+/-0.004 vs. 0.12+/-0.05 RU; P = 0.01). Similar results were obtained for normalization to glyceraldehyde-3-phosphate dehydrogenase mRNA. Our data suggest an increase of placental leptin production with gestational age. In patients with preeclampsia, elevated leptin expression goes along with suppressed NPY expression. This resembles hypothalamic regulation.

Laparoscopically performed gastric banding in a 13 year-old girl with morbid obesity and end stage renal insufficiency allows lifesaving weight loss and hemodialysis.

OBJECTIVE: In adults, laparoscopic gastric banding is applied to treat morbid obesity, usually in combination with dietary and psychological intervention and increased physical exercise. However, little information is available on gastric banding in children. PATIENT AND METHODS: The 13 year-old girl suffered from end stage renal failure. Complications with hemodialysis catheters due to her extensive subcutaneous fat pads led to a life-threatening deterioration of her uremia. Intensive conventional schedules for weight reduction failed to be effective, so the morbidly obese girl (body mass index [BMI] 37.7 kg/m2, +3.6 standard deviation score [SDS]) underwent laparoscopic gastric banding at the age of 13 years after informed parental consent was obtained. RESULTS: After laparoscopic gastric banding there was a notable weight loss of 14 kg and an eventually adequate hemodialysis was possible. Total weight loss of the now 15 year-old girl was 24 kg (present BMI 28.3 kg/m2, +2.2 SDS). CONCLUSION: Even in childhood, laparoscopic gastric banding may be considered in cases of morbid obesity in critically ill patients.