Fibrillin-1 regulates mesangial cell attachment, spreading, migration and proliferation

The microfibrillar protein fibrillin-1 is present in many organs, including the vasculature, eye, and dermis, and is thought to convey structural anchorage and elastic strength. Fibrillin-1 is also a component of the mesangial matrix. To assess the functional relevance of fibrillin-1 for cell-matrix interactions in the glomerulus, we studied the attachment, spreading, migration and proliferation of mesangial cells on fibrillin-1 and the regulation of fibrillin-1 in experimental anti-Thy1.1 nephritis displaying mesangial cell migration and proliferation in vivo. During the acute phase of experimental Thy1.1 nephritis, glomerular fibrillin-1 messenger ribonucleic acid expression and protein immunoreactivity were significantly induced as compared to controls. In a hexosaminidase-based adhesion assay, mesangial cells showed concentration-dependent attachment to fibrillin-1, similar to what was observed for fibronectin. The cell attachment was Arg-Gly-Asp dependent. Further, fibrillin-1 significantly promoted spreading and focal contact formation detected by immunostaining for vinculin. Mesangial cell migration, assessed by a transmigration assay, and proliferation, measured by a 5-bromo-2'-deoxy-uridine incorporation assay, were augmented by fibrillin-1. In diabetic mice underexpressing fibrillin-1, glomerular cell proliferation, determined by counting proliferating cell nuclear antigen-positive cells in renal sections, was significantly lower than in diabetic control mice. We conclude that fibrillin-1 promotes mesangial cell attachment, spreading, migration, and proliferation. We speculate that fibrillin-1 may thus contribute to mesangial hypercellularity during glomerular disease.

[Denys-Drash syndrome. Experience gathered in Erlangen illustrated by two case reports]

Denys-Drash syndrome is a rare symptom complex associated with obligatory childhood nephrotic syndrome, male pseudohermaphroditism, and Wilms' tumor. The etiology of Denys-Drash syndrome is attributed to a mutation of the WT1 gene. We report on two cases of Deny-Drash syndrome confirmed by genetic testing. Rapidly evolving terminal renal insufficiency was detected in both patients necessitating bilateral nephrectomies with prophylactic intent. In one of the patients, a Wilms' tumor had already been verified in one kidney so that chemotherapy had to be initiated.The risk of Wilms' tumor is very high in patients with a WT1 mutation, which leads to the need for removal of both kidneys during or before transplantation. It would be important to perform a diagnostic work-up for WT1 gene mutation in children who develop renal failure in the 1st year of life.

Serum cortisol and cortisone levels in newborns with congenital adrenal hyperplasia before the start of therapy

Sodium loss in infants with salt wasting (SW) congenital adrenal hyperplasia (CAH) does usually not occur within the first week of life. We hypothesized that sufficient mineralocorticoid activity might by temporarily maintained by still appropriate concentrations of cortisol. Plasma samples were obtained from 15 infants with SW-CAH before the onset of sodium loss, 17 patients with simple virilizing (SV)-CAH and 28 healthy infants under 14 days of age. Plasma aldosterone concentrations were significantly lower in SW-CAH infants than in SV-CAH patients and in healthy neonates. Plasma cortisol levels and cortisol/cortisone (F/E) ratios in SW-CAH patients were almost the same as in the SV-CAH and control group. While declining plasma aldosterone levels precede the onset of SW in CAH patients, plasma cortisol concentrations are kept normal in SW-CAH infants, temporarily maintaining sufficient mineralocorticoid activity.

Salivary leptin induces increased expression of growth factors in oral keratinocytes

We investigated the influence of salivary leptin, purified by affinity chromatography, on the proliferation of human oral keratinocytes. Furthermore we determined the time- and dose-dependency of the incubation with salivary leptin on the production of epidermal growth factor (EGF) and keratinocyte growth factor (KGF), which are growth factors relevant to keratinocyte proliferation. The analysis was performed both intra- and extracellularly. The relationship between the three cytokines in cell proliferation was studied by successive blocking with specific antibodies. The incubation of oral keratinocytes with recombinant and native leptin led to a significantly increased, dose-dependent cell proliferation (P<0.001). A further significant increase in proliferation was observed after incubating the cells with sterile filtered saliva (P<0.001). The increase in proliferation could not be observed by simultaneous incubation with salivary leptin and specific antibodies against either leptin or KGF (P<0.001). We found a significant dose-dependency between leptin incubation and production of KGF and EGF at the RNA and protein level. Both cytokines were expressed intracellularly and released into the culture medium, where they could be quantified by ELISA. Furthermore, there was a dose- and time-dependent increase in the phosphorylation of STAT-1 and STAT-3, indicating that Ob-R(b) (the long form of the leptin receptor) expressed by the keratinocytes is functional. It is conceivable that the leptin-induced proliferation in keratinocytes is mediated by this signalling pathway. This is the first study to show a physiological role of salivary leptin as a growth factor for keratinocyte proliferation in the oral cavity. We could demonstrate its influence on the production of other growth factors essential for this proliferative effect. Based on the findings of our study we assume an important role for salivary leptin in wound healing within the vulnerable oral cavity.

Frühe Einflussfaktoren auf das Körpergewicht und die Prävalenz von Übergewicht zum Zeitpunkt der Schuleingangsuntersuchung bei 4610 Kindern im Raum Erlangen/Nordbayern

OBJECTIVE

Childhood obesity is a growing health problem among German children. Birth weight is considered to have a major influence on the course of postnatal weight. The present study investigates the relation between birth weight and body weight at health examination prior to school entry. We tested other parameters influencing childhood obesity, and hypothesized that within a 5-year interval the prevalence of obesity in children has increased significantly.

METHODS

Our study is based on the retrospective analysis of the school enrolment health examinations of 4610 children in North Bavaria, e. g. the town Erlangen and administrative district Erlangen-Hoechstadt in 1995/96 and 2000/01.

RESULTS

A higher birth weight was associated with a higher weight and BMI at school entry examination (p < 0.0001). An increased birth weight is therefore a considerable risk factor for later overweight in childhood. Hypotrophic newborn, however, gain less weight and exhibit a lower BMI in our study group. In general, boys were significantly heavier than girls (p < 0.001). Children of foreign origin were heavier and had a higher BMI corrected for age than German pupils but they were also 0.07 years older. Our regional survey revealed local differences in the prevalence of obesity. Comparing the cohorts 1995/96 and 2000/01 at school entry, a significant increase of BMI in the latter was found (p < 0.0001).

CONCLUSIONS

A highly significant increase in the prevalence of infantile overweight has to be faced. Early prevention of childhood obesity is therefore mandatory to avoid the complications and higher morbidity.

Maturation of the expression of adrenomedullin, endothelin-1 and nitric oxide synthases in adipose tissues from childhood to adulthood

OBJECTIVE

To investigate if the vasoactive systems adrenomedullin (ADM) and endothelin-1 (ET-1) are expressed in human adipose tissues in children and in adults and to determine the distribution pattern of nitric oxide synthases (NOS).

DESIGN AND SUBJECTS

Subcutaneous, mesenterial and omental adipose tissue specimens taken from 15 children (age 0.5-16 y, median 6 y) and 13 adults (age 43-79 y, median 60 y) were analyzed. The body mass indices (BMI) were within the normal range. All patients were normotensive, and were free of infectious disease, and metabolic or endocrine disorders. The specimens were taken during elective laparotomies after informed consent was obtained.

MEASUREMENTS

ADM, ET-1, the endothelial (eNOS) and inducible (iNOS) NOS as well as two housekeeping genes were measured using quantitative real-time PCR.

RESULTS

ADM gene expression was found at all locations, and was significantly higher in adults than in children (P<0.01 for subcutaneous and omental adipose tissue). ET-1 mRNA was distributed in a similar way, showing significantly higher levels in the subcutaneous and mesenterial adipose tissue sections of adults than of children. For eNOS, the adult patients exhibited a higher expression in subcutaneous and mesenterial specimens than the children (P<0.01 and P<0.05). The iNOS mRNA was increased in subcutaneous, mesenterial and omental adipose tissues in the adult cohort compared to the children's levels (P<0.05 to P<0.01).

CONCLUSION

Human adipose tissue expresses many vasoactive substances including ADM and ET-1. In adults, the amounts of ET-1 and ADM as well as eNOS and iNOS mRNA are higher, possibly due to a physiological upregulation with increasing age. Although there are differences depending on the locations of the tissues, the expression patterns of the antagonists ADM and ET-1 are quite similar, indicative of a well-balanced pattern of local gene expression in normotensive individuals with normal body weight.

Brief adrenomedullin inhalation leads to sustained reduction of pulmonary artery pressure

The effect of aerosolised adrenomedullin (ADM), a potent vasodilator peptide, on pulmonary artery pressure was studied for 24 h in a surfactant-depleted piglet model. Animals received either aerosolised ADM (50 ng.kg(-1).min(-1), ADM, n=6), or aerosolised normal saline solution (control, n=6). Aerosol therapy was performed for a 2 h treatment period followed by a 22 h observation period. Ventilator settings were adapted to keep arterial oxygen tension and carbon dioxide arterial tension between 13.3-14.6 kPa and 4.9-5.7 kPa, respectively. Aerosolised ADM reduced mean pulmonary artery pressure (MPAP) compared with the control group (end-point median 24 h after therapy start: DeltaMPAP -14.0 versus -8.0 mmHg; 23.5 h after therapy start). After therapy start, mean systemic arterial pressure (MAP) was not significantly different between the groups (end-point median: MAP ADM 70 (61/74) versus control 72 (54/81) mmHg). Endothelin-1, a potent pulmonary vasoconstrictor, is regulated by ADM via cAMP. Twenty two hours after inhalation of aerosolised ADM, endothelin-1 mRNA in lung tissue and endothelin-1 protein expression in pulmonary arteries was reduced compared with controls (median semi-quantitative immunhistochemical score: ADM 0.21, control 0.76). Aerosolised adrenomedullin significantly reduced mean pulmonary artery pressure independently of arterial oxygen tension.

Endogenous retroviral syncytin: compilation of experimental research on syncytin and its possible role in normal and disturbed human placentogenesis

Placental syncytin was first described in the year 2000 as a fusogenic glycoprotein originally derived from a human endogenous retroviral envelope gene. Although the presence of stable integrated retroviral elements within the human genome has been known for many years, their biological significance is still obscure and has usually been designated as irrelevant or even harmful. Syncytin, however, demonstrates tissue-specific expression and distinctive receptor interaction during trophoblast cell differentiation and syncytium formation. These findings indicate an involvement of syncytin in the development of the human placenta. Disturbances in placental architecture leading to severe placental dysfunction, such as pre-eclampsia, may therefore be discussed as a consequence of an altered syncytin system. We evaluate the hypothesis that syncytin is essential for human placenta formation and may also have played an important role in human placental evolution.

Comparison of leptin gene expression in different adipose tissues in children and adults

OBJECTIVE

Adipose tissue displays depot-specific metabolic properties and a predominant gene expression of leptin in subcutaneous tissue. The aim of the study was to evaluate leptin mRNA expression in various adipose tissues and to relate it to plasma leptin concentrations. Furthermore, developmental changes in leptin gene expression from childhood to adulthood were examined.

DESIGN AND METHODS

Thoracic subcutaneous and intrathoracic adipose tissue specimens were obtained in 22 adults (51-81 years) and 23 children (0.1-17 years) undergoing cardiac surgery, and abdominal subcutaneous, omental and mesenterial fat specimens were collected from 21 adults (38-79 years) and 22 children (0.2-17 years) before abdominal surgery. Preoperative plasma leptin concentrations were measured by RIA. Leptin mRNA expression was quantified by TaqMan real-time PCR.

RESULTS

In adults, there was no difference between leptin gene expression in subcutaneous and intrathoracic fat, whereas in children leptin mRNA expression was significantly higher in subcutaneous adipose tissue. In omental fat, leptin mRNA levels were significantly lower compared with subcutaneous and mesenterial sites in both children and adults. Adults revealed a significantly higher leptin gene expression in subcutaneous, omental and mesenterial adipose tissues than children. Subcutaneous and omental leptin gene expression are independent factors for plasma leptin concentrations in children and adults.

CONCLUSION

Leptin is differentially expressed at different adipose tissue sites, a situation which is even more pronounced in children. There is a developmental increase in leptin mRNA expression in adipose tissue during childhood, reaching maximal capacity in adulthood.

A new missense mutation of the vasopressin-neurophysin II gene in a family with neurohypophyseal diabetes insipidus

OBJECTIVE

Autosomal dominant familial neurohypophyseal diabetes insipidus is a rare disorder characterized by polydipsia and polyuria. We present the results of the molecular analysis of the AVP-NPII gene of a German kindred.

METHODS

All three exons of the gene were amplified by polymerase chain reaction and sequenced.

RESULTS

In 7 affected individuals a new missense mutation (1770G > T) in exon 2 was found predicting a cysteine to phenylalanine substitution at codon 58 in the neurophysin II domain (NPII).

CONCLUSION

As a result of this mutation a cysteine residue is exchanged, which is involved in a disulfide bond with cysteine 44 of the NPII moiety, hypothesizing that the resulting misfolded protein may lead to chronic neurotoxicity by accumulation of these products in the endoplasmatic reticulum.

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.

Spontaneous nocturnal leptin secretion in children with myelomeningocele and growth hormone deficiency

OBJECTIVE

To examine the spontaneous leptin secretion in patients with myelomeningocele (MMC) and growth hormone deficiency (GHD).

METHODS

Serum leptin levels were studied in 10 prepubertal MMC patients with GHD (CA 6.2 +/- 0.5 years), 10 patients with idiopathic GHD (IGHD; CA 7.6 +/- 0.7 years) and 12 children with normal variant short stature (NVSS; CA 7.6 +/- 0.5 years). Mean BMI (kg/m(2)) values of the groups did not differ significantly. Nocturnal leptin levels were analyzed over 10 h (blood samples every 20 min) and measured by specific radioimmunoassay.

RESULTS

Mean leptin concentrations did not correlate with BMI in MMC patients. Nocturnal leptin secretion of MMC patients was significantly different to those of children with IGHD and NVSS. Morning leptin levels did not decline as observed in both other groups.

CONCLUSION

Since all groups were matched for BMI values, we suggest a hypothalamic dysregulation of leptin secretion in MMC patients.

Hypoxia activates the human placental vascular endothelial growth factor system in vitro and in vivo: up-regulation of vascular endothelial growth factor in clinically relevant hypoxic ischemia in birth asphyxia

OBJECTIVE

We investigated the influence of acute hypoxia on the placental vascular endothelial growth factor system in vitro and in vivo in acute birth asphyxia compared with pregnancies that were complicated by preeclampsia and with healthy control subjects.

STUDY DESIGN

Messenger RNA levels for vascular endothelial growth factor, flt-1, and KDR were measured by TaqMan real-time polymerase chain reaction in human placental choriocarcinoma cells (BeWo) that were exposed to hypoxia (1% oxygen, 5% carbon dioxide, 94% nitrogen) and in placental tissue of neonates with birth asphyxia (n = 20), newborn infants of mothers with preeclampsia (n = 20), and gestational age-matched control subjects. Immunhistologically, placental vascular endothelial growth factor protein expression was compared among the groups.

RESULTS

In BeWo cells, vascular endothelial growth factor, flt-1 and KDR messenger RNA increased in a time-dependent manner in response to hypoxia. In vivo, vascular endothelial growth factor/beta-actin and KDR/beta-actin messenger RNA were significantly higher in placental tissue of newborn infants with severe hypoxic-ischemic encephalopathy than with newborn infants with mild or no hypoxic-ischemic encephalopathy and control subjects. In chronic placental hypoxia (preeclampsia), vascular endothelial growth factor and both receptors were found to be up-regulated. Increased placental vascular endothelial growth factor expression was confirmed by immunohistologic examination.

CONCLUSION

The vascular endothelial growth factor system is up-regulated in response to placental hypoxia and is assumed to be a potential early indicator of severe birth asphyxia.

Nitric oxide stimulates adrenomedullin secretion and gene expression in endothelial cells

Adrenomedullin, a peptide with vasorelaxant activity, stimulates nitric oxide (NO) synthesis. We tested whether or not NO regulates the function of the adrenomedullin system. Human umbilical vein endothelial cells (HUVEC) were incubated with the NO donors sodium nitroprusside (SNP), morpholinosydnonimine (SIN-1) and the phospodiesterase V inhibitor zaprinast. In HUVEC, adrenomedullin concentration in the supernatant was measured by radioimmunoassay and mRNA expression was studied by Northern blot and competitive quantitative PCR. SNP, SIN-1, and zaprinast (100 micromol/l each) significantly increased adrenomedullin concentration in the supernatant of HUVEC twofold. The same concentrations increased adrenomedullin mRNA expression four- to tenfold. Similar results were obtained by both quantitative PCR and Northern blot. Thus, NO donor exposure in vitro increases both adrenomedullin secretion and mRNA expression in a dose-dependent manner.

Increased endothelin-1 and decreased adrenomedullin gene expression in the stenotic tissue of congenital pelvi-ureteric junction obstruction in children

OBJECTIVES

To test the hypothesis that the gene expression of endothelin-1 and adrenomedullin may be altered in stenotic tissues of patients with congenital hydronephrosis caused by pelvi-ureteric junction (PUJ) obstruction.

MATERIALS AND METHODS

Using real-time reverse transcription-polymerase chain reaction, mRNA of smooth muscle-constricting endothelin-1 and of smooth muscle-relaxing adrenomedullin was quantified in tissue specimens of 20 patients with PUJ obstruction (mean age 5.1 years, SD 7.0) and of 21 controls with normal PUJs (mean age 23.5 years, SD 24.2).

RESULTS

The amount of endothelin-1 mRNA in stenotic specimens was higher than in the controls, indicated by significantly lower threshold cycles (Ct values) in real-time PCR for the target gene in the obstructive tissue, with mean (SD) values of 24.9 (1.6) and 26.0 (2.1) (P < 0.05), respectively. The endothelin-1/CD31 ratio was significantly higher in the patients (P < 0.05) than in controls. In addition, adrenomedullin gene expression in the obstructed junctions was significantly lower than in normal junctions, with higher Ct values for the patient group of 26.7 (1.6) vs 25.2 (1.8) (P < 0.05) and lower adrenomedullin mRNA when standardized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (P < 0.05), CD31 (P < 0.01) and smooth muscle alpha-actin mRNA (P < 0.01). The two groups showed no significant differences for GAPDH and CD31 mRNA content, whereas there was about twice as much alpha-actin mRNA in stenotic tissues than in unaffected PUJs, shown by the lower Ct values for the patient group of 16.9 (2.0) vs 17.9 (2.6) (P < 0.05). Furthermore, endothelin-1, adrenomedullin and alpha-actin mRNA amounts were independent of age.

CONCLUSION

Taken together these results provide evidence that the production of autocrine/paracrine acting endothelin-1 and adrenomedullin is altered in tissues of patients with genuine PUJ obstruction, and may be involved in the pathogenesis of congenital hydronephrosis.