No abstract

Leptin is a circulating hormone that is secreted primarily by adipose tissue. However, recent studies have demonstrated leptin production by other tissues, including placenta, stomach, kidney, liver, and lung, a process not only activated by stimuli such as insulin or corticosteroids, but also by hypoxia, which is mediated by the hypoxia inducible factor-1. In contrast to this fact, smokers have lower plasma leptin levels. The purpose of this study was to determine whether tissue hypoxygenation [induced by lack of oxygen] or inhalation of carbon monoxide (CO) are sufficient to up-regulate leptin in fat cells as well as in peripheral organs such as lung, liver, and kidney of rats. In hypoxic rats, leptin expression was unchanged or even reduced in adipose tissue. In contrast, in liver, kidney, and lung we observed an increase in leptin expression compared with normoxic controls, whereas plasma levels were unchanged. When animals were exposed to CO, generating a functional anemia known to activate the HIF-1-dependent transcription, a significant decrease in leptin gene expression in adipose tissue and in all organs tested was observed. Plasma leptin concentrations after CO exposure were significantly diminished compared with those in control animals. These findings suggest that tissue hypoxygenation up-regulates leptin expression in nonadipose tissue. However, this is not sufficient to raise plasma leptin levels in rats. Inhalation of CO leads to a significant decrease in leptin mRNA and protein concentration in the plasma of the animals, suggesting a negative effect of CO on leptin transcription.

Objective: The ob-gene product, leptin, is an important regulator of placental and fetal development during pregnancy. Leptin, being induced by hypoxia in the placenta, is a known pro-apoptotic molecule in adipose tissue but is also known to inhibit apoptosis in other tissues like neuroblastoma cells. Based on these findings, we investigated if leptin has a pro-or anti-apoptotic effect on a trophoblastic cell line (JAr cells) in the presence or absence of oxygen. Methods and results: Measurement of leptin in the supernatant by using ELISA showed hypoxiainduced leptin production in JAr cells in vitro. This could be confirmed by a leptin-specific RT-PCR. By analyzing leptin and/or hypoxia exposed cells with FACS cytometry we found that JAr cells can cope with hypoxia down to oxygen tensions of 1%. At this level, only a small number of cells underwent apoptosis. Interestingly, leptin added to the culture medium in high concentrations was not able to interfere with the rate of proliferation or apoptosis in these cells independent of the oxygen tension. Finally, an anti-caspase-3 and anti-caspase-9 Western blot was performed. Again, no difference in the expression of caspase-3 and -9 under the conditions tested was seen. Conclusions: These results show that leptin, produced by placental cells after hypoxia in vitro, has no influence on the rate of proliferation of these cells. Furthermore, it does not influence apoptotic pathways in the trophoblastic cell line tested under hypoxic and non-hypoxic conditions. European Journal of Endocrinology 153 455-461

No abstract

Postnatal nutrition and stressors such as LSR lead to dysregulated signalling of NPY. These data demonstrate that factors in the early postnatal environment exert important changes in the tubular function, which may predispose to corresponding pathology.

Background The role of B cells in inflammatory bowel disease (IBD) is ambiguous, as B cells may have both pathogenic and protective functions in IBD. We studied B cell subsets before and after initiation of an anti-tumor necrosis factor alpha (anti-TNFα) therapy in pediatric IBD. The aim of the study was to examine the behavior of B cells in pediatric IBD patients undergoing an anti-TNFα therapy and, more specifically, to clarify their association with a successful or an unsuccessful infliximab (IFX) treatment. Methods A total of N = 42 pediatric IBD patients (Crohn disease, n = 30; ulcerative colitis, n = 12) for whom an anti-TNFα therapy with and without a concomitant azathioprine (AZA) medication was administered were recruited. Fourteen healthy age-matched children served as control patients. Blood samples were collected before initiation of the anti-TNFα therapy, before the fourth infusion at the end of the induction phase, and after 6 and 12 months under therapy maintenance. Flow cytometry (CD20, CD27, CD38, CD138) and intracellular staining (interleukin 10 [IL10], TNFα, granzyme B) were performed. Responders to successful IFX therapy were classified exhibiting a fecal calprotectin level of below 100 µg/g or achieving levels of <10% of the baseline value at initiation than at the end of the 12-month follow-up period. Results Before initiation of anti-TNFα therapy, flow cytometry revealed increased percentages of naïve B cells whereas transitional B cells were reduced compared with those in the healthy control patients. The IL10-producing B cells of both ulcerative colitis and Crohn disease patients were reduced at the initiation of IFX therapy, whereas TNFα-producing transitional CD24hiCD38hi B cells in ulcerative colitis patients were increased compared with those in healthy control patients. After 12 months of therapy, we detected a significant increase of IL10-producing transitional B cells in responding patients. The IFX trough levels in the responding patients showed a significant increase until 6 months after IFX initiation, attaining mean values of 9.9 µg/mL, whereas the IFX dosage was significantly lower than that in the nonresponding patients. The IFX trough levels in AZA-treated patients reached earlier therapeutic levels than in patients without AZA comedication, whereas during the course of the IFX therapy, comedication with AZA had no significant effect on the outcome. Conclusions Attaining a normalization of IL10 production among CD24hiCD38hi B cells after 12 months of therapy may represent additional information about the reconstitution of a patient’s immune system in responding patients. The achievement of an IFX trough level of ~10 µg/mL at 6 months of treatment is associated with a successful anti-TNFα therapy. In addition, AZA comedication supports an earlier achievement of therapeutic IFX trough levels.

Objectives: The physiological number and distribution of mast cells (MCs) in the pediatric gastrointestinal (GI) tract is not well defined and reference values of normality are missing. To define a physiological and disease defining cut-off, a systematic histological exploration of MC distribution from the esophagus to the rectum in healthy as well as in patients with gastrointestinal food allergies (GFA) was performed. Methods: Nine pediatric subjects that exhibited unremarkable histopathological evaluations or underwent endoscopy for surveillance reasons after a previous polypectomy of single colonic juvenile polyps served as reference cohort. In all of these subjects, a chronic inflammatory disease (eg, inflammatory bowel disease, celiac disease) or allergy was excluded. In addition, a group of 15 patients with gastrointestinal complaints suspected to be caused by a GFA were investigated. Immunohistochemistry was performed from all biopsies using CD117 (c-Kit) as a reliable marker to identify MCs in the lamina propria. Results: There were distinct differences of MC counts in all parts of the pediatric GI tract. The highest counts of MCs in both symptomatic patients and control cohort, were found in the duodenum, terminal ileum, cecum and ascending colon. The lowest counts were found in the esophagus. Significant disparities between GFA and healthy subjects were found in the gastric corpus (22.1 AE 4.0/ high power field [HPF] vs 32.0 AE 10.1/HPF; P ¼ 0.034) and ascending colon (44.8 AE 10.4/HPF vs 60.4 AE 24.3/HPF; P ¼ 0.047). Conclusions: Mucosal MC counts in the pediatric GI tract are higher than previously reported, with a considerable overlap between healthy and GFA patients. These results provide detailed information on distribution and numbers of MCs in pediatric allergic patients while allowing estimates of physiological values in childhood for the first time. With regard to diagnostic procedures in GFA further laboratory parameters have to be integrated.

The hypoxia-inducible factor 1α (HIF-1α), a member of the PAS superfamily, is a global regulator of cellular and systemic O₂ homeostasis as well as embryonic development. As the activity of HIF-1α is increased by a lowered oxygen tension in vivo and in vitro, we established a cell line producing high amounts of HIF-1α under normoxic conditions. As this overexpression was inducible by doxycycline, we can now provide a system to study HIF-1α-dependent gene regulation under normoxic as well as hypoxic conditions. We were able to show that the doxycycline-induced induction of the target gene HIF-1α – followed by the message of its target genes erythropoietin and vascular endothelial growth factor – is a dose- and time-dependent process. As the inducible overexpression of HIF-1α did not increase the rate of apoptosis, it provides a helpful new tool in drug discovery and tumor research to differentiate between hypoxia-dependent and hypoxia-independent pathways during HIF-1α-dependent gene regulation and HIF-1α-dependent effects on apoptosis.