Carlos Menendez-Castro

Early and Late Postnatal Myocardial and Vascular Changes in a Protein Restriction Rat Model of Intrauterine Growth Restriction

Intrauterine growth restriction (IUGR) is a risk factor for cardiovascular disease in later life. Early structural and functional changes in the cardiovascular system after IUGR may contribute to its pathogenesis. We tested the hypothesis that IUGR leads to primary myocardial and vascular alterations before the onset of hypertension. A rat IUGR model of maternal protein restriction during gestation was used. Dams were fed low protein (LP; casein 8.4%) or isocaloric normal protein diet (NP; casein 17.2%). The offspring was reduced to six males per litter. Immunohistochemical and real-time PCR analyses were performed in myocardial and vascular tissue of neonates and animals at day 70 of life. In the aortas of newborn IUGR rats expression of connective tissue growth factor (CTGF) was induced 3.2-fold. At day 70 of life, the expression of collagen I was increased 5.6-fold in aortas of IUGR rats. In the hearts of neonate IUGR rats, cell proliferation was more prominent compared to controls. At day 70 the expression of osteopontin was induced 7.2-fold. A 3- to 7-fold increase in the expression of the profibrotic cytokines TGF-β and CTGF as well as of microfibrillar matrix molecules was observed. The myocardial expression and deposition of collagens was more prominent in IUGR animals compared to controls at day 70. In the low-protein diet model, IUGR leads to changes in the expression patterns of profibrotic genes and discrete structural abnormalities of vessels and hearts in adolescence, but, with the exception of CTGF, not as early as at the time of birth. Invasive and non-invasive blood pressure measurements confirmed that IUGR rats were normotensive at the time point investigated and that the changes observed occurred independently of an increased blood pressure. Hence, altered matrix composition of the vascular wall and the myocardium may predispose IUGR animals to cardiovascular disease later in life.

Intrauterine Growth Restriction following Ligation of the Uterine Arteries Leads to More Severe Glomerulosclerosis after Mesangioproliferative Glomerulonephritis in the Offspring

Background: Low birth weight is a risk factor for the development of a more severe course of secondary renal diseases. We tested the hypothesis that experimental mesangioproliferative glomerulonephritis (GN) shows an aggravated course in rats inflicted with experimental uteroplacental insufficiency during gestation. Methods: Intrauterine growth restriction (IUGR) was induced by ligation of both uterine arteries on day 19 in pregnant Wistar rat dams. GN was induced in male offspring at the age of 9 weeks by intravenous injection of an anti-Thy-1.1 antibody. At day 14 of GN, kidneys were taken and analyzed for glomerular morphometry, markers of inflammation, glomerulosclerosis and tubulointerstitial fibrosis. Results: Despite a similar extent of mesangiolysis, former IUGR animals presented with a higher level of glomerulosclerosis and increased deposition of glomerular collagens I and IV compared to nephritic control animals. Arterial blood pressure, renal function, and proteinuria after 14 days of GN were not influenced by former IUGR. Conclusion: Ligation of the uterine arteries in the rat leads to more pronounced sclerotic changes in the glomerulus in the offspring suffering from acute GN. This finding supports the hypothesis that former IUGR increases the susceptibility for a more severe course of secondary renal diseases.

Corticotropin-releasing hormone stimulates expression of leptin, 11beta-HSD2 and syncytin-1 in primary human trophoblasts

BackgroundThe placental syncytiotrophoblast is the major source of maternal plasma corticotropin-releasing hormone (CRH) in the second half of pregnancy. Placental CRH exerts multiple functions in the maternal organism: It induces the adrenal secretion of cortisol via the stimulation of adrenocorticotropic hormone, regulates the timing of birth via its actions in the myometrium and inhibits the invasion of extravillous trophoblast cells in vitro. However, the auto- and paracrine actions of CRH on the syncytiotrophoblast itself are unknown. Intrauterine growth restriction (IUGR) is accompanied by an increase in placental CRH, which could be of pathophysiological relevance for the dysregulation in syncytialisation seen in IUGR placentas.MethodsWe aimed to determine the effect of CRH on isolated primary trophoblastic cells in vitro. After CRH stimulation the trophoblast syncytialisation rate was monitored via syncytin-1 gene expression and beta-hCG (beta-human chorionic gonadotropine) ELISA in culture supernatant. The expression of the IUGR marker genes leptin and 11beta-hydroxysteroid dehydrogenase 2 (11beta-HSD2) was measured continuously over a period of 72 h. We hypothesized that CRH might attenuate syncytialisation, induce leptin, and reduce 11beta-HSD2 expression in primary villous trophoblasts, which are known features of IUGR.ResultsCRH did not influence the differentiation of isolated trophoblasts into functional syncytium as determined by beta-hCG secretion, albeit inducing syncytin-1 expression. Following syncytialisation, CRH treatment significantly increased leptin and 11beta-HSD2 expression, as well as leptin secretion into culture supernatant after 48 h.ConclusionThe relevance of CRH for placental physiology is underlined by the present in vitro study. The induction of leptin and 11beta-HSD2 in the syncytiotrophoblast by CRH might promote fetal nutrient supply and placental corticosteroid metabolism in the phase before labour induction.

The tumor suppressor gastrokine-1 is expressed in placenta and contributes to the regulation of trophoblast migration

INTRODUCTION Gastrokine-1 (GKN1) is a secreted auto-/paracrine protein, described to be expressed in the gastric mucosa. In gastric cancers GKN1 expression is commonly down-regulated. While current research focusses on the exploration of tumor-suppressive properties of GKN1 with regard to its potential clinical use in the treatment of gastroenterologic tumor disease, nothing is known about GKN1 expression and function in other organ systems. We investigated GKN1 expression in placental tissue and cells. MATERIALS AND METHODS GKN1 was localized using immunohistochemistry in first and third trimester placental tissue, hydatidiform moles and various gestational trophoblastic neoplasias. We determined the expression of GKN1 in immunomagnetic bead-separated term placental cells and in choriocarcinoma cell lines. The role of GKN1 for JEG-3 migration was studied using live cell imaging. E-cadherin, MMP-2 and -9, TIMP-1 and -2, as well as urokinase (uPA) expression levels were determined. RESULTS GKN1 is expressed in healthy third trimester placentas. Its expression is specifically limited to the extravillous trophoblast (EVT). GKN1 expression is significantly reduced in choriocarcinoma cell lines and gestational trophoblastic neoplasias. GKN1 attenuates the migration of JEG-3 choriocarcinoma cells in vitro, possibly via AKT-mediated induction of E-cadherin. GKN1 treatment reduced MMP-9 expression in JEG-3. DISCUSSION Besides its role in gastric physiology our results clearly indicate regulatory functions of GKN1 in the EVT at the feto-maternal interface during pregnancy. Based on our findings in the JEG-3 choriocarcinoma cell line, an auto-/paracrine role of GKN1 for EVT motility and villous anchorage at the basal plate is conceivable. Thus, the tumor suppressor GKN1 is expressed in placental EVT and might contribute to the regulation of EVT migration/invasion.

Impaired myocardial performance in a normotensive rat model of intrauterine growth restriction.

Background:Intrauterine growth restriction (IUGR) is an important risk factor for cardiovascular disease. Previous studies revealed altered myocardial matrix composition after IUGR. We hypothesized that IUGR is accompanied by compromised myocardial performance independently from arterial hypertension.Methods:IUGR was induced in Wistar rats by maternal protein restriction, and hearts of male offspring were studied using echocardiography, immunohistochemistry, real-time PCR, and western blot analysis.Results:At day 70 of life, in the absence of arterial hypertension (mean arterial blood pressure: 101.3 ± 7.1 mmHg in IUGR vs. 105.3 ± 4.6 mmHg in controls, not significant (NS)), echocardiography showed a reduced contractility (ejection fraction: 65.4 ± 1.8% in IUGR vs. 82.2 ± 1.5% in controls, P < 0.001) of a more distensible myocardium in IUGR rats. Altered expression patterns of myosin chains and titin isoforms and increased expression levels of atrial natriuretic peptide, Na/K-ATPase, and β-adrenergic receptor 1 were detected. A higher number of cardiac fibroblasts and vascular cross-sections were observed in IUGR rats, accompanied by elevated expression of hypoxia inducible factor 1 target genes, such as vascular endothelial growth factor and its receptors.Conclusion:We observed a blood pressure–independent impairment of myocardial function after IUGR, which possibly favors cardiovascular disease later in life. Some IUGR-induced myocardial changes (e.g., sarcomeric components) may partly explain the compromised cardiac performance, whereas others (e.g., elevated vascular supply) reflect compensatory mechanisms.

Tubulointerstitial De Novo Expression of the α8 Integrin Chain in a Rodent Model of Renal Fibrosis – A Potential Target for Anti-Fibrotic Therapy?

In the normal kidney, the α8 integrin chain is expressed only on mesangial cells and vascular smooth muscle cells. α8 integrin ligates several matrix molecules including fibronectin, osteopontin and fibrillin-1. Recently, we detected de novo expression of α8 integrin on epithelial cells in renal cysts. We hypothesized that the α8 integrin chain is induced in tubular epithelia undergoing dedifferentiation and contributes to the fibrotic response in the tubulointerstitium (TI) after unilateral ureteral obstruction (UUO). After induction of UUO in rats by ligation of the right ureter, increased expression of the α8 integrin chain and its ligands was observed. In the TI, α8 integrin was localized to cytokeratin-positive epithelial cells and to interstitial fibroblasts; and colocalized with its ligands. In mice underexpressing α8 integrin UUO led to collagen deposition and fibroblast activation comparable to wild types. Mice lacking α8 integrin showed even more TI damage, fibroblast activation and collagen deposition after UUO compared to wild type mice. We conclude that the expression of the α8 integrin chain and its ligands is strongly induced in the TI after UUO, but underexpression of α8 integrin does not attenuate TI fibrosis. Mice lacking the α8 integrin chain are even more susceptible to TI damage than wild type mice. Thus, interactions of α8 integrin with its ligands do not seem to contribute to the development or progression of TI fibrosis in UUO. Targeting α8 integrin might not be a useful approach for anti-fibrotic therapy.

Lack of α8-integrin aggravates podocyte injury in experimental diabetic nephropathy

Development of diabetic nephropathy is accompanied by changes in integrin-mediated cell-matrix interactions. The α8-integrin chain is specifically expressed in mesangial cells of the glomerulus. During experimental hypertension, α8-integrin plays a protective role in the glomerulus. We hypothesized that α8-integrin is involved in maintaining the integrity of the glomerulus in diabetic nephropathy. Experimental streptozotocin (STZ) diabetes led to an increased expression and glomerular deposition of α8-integrin. To test the functional role of α8-integrin, STZ diabetes was induced in mice with a homozygous (α8-/-) or heterozygous (α8+/-) deletion of the α8-integrin gene and in wild-type litters (α8+/+). Blood glucose and mean arterial blood pressure were not different in α8-/- and α8+/+ mice after 6 wk of diabetes. However, diabetic α8-/- mice developed significantly higher albuminuria and more glomerulosclerosis than diabetic α8+/+ mice. Moreover, in diabetic α8-/- mice, the number of glomerular cells staining positive for the podocyte markers WT-1 and vimentin were reduced more prominently than in diabetic α8+/+. The filtration barrier protein nephrin was downregulated in diabetic glomeruli with the strongest reduction observed in α8-/- mice. Taken together, α8-/- mice developed more severe glomerular lesions and podocyte damage after onset of STZ diabetes than α8+/+ mice, indicating that α8-integrin is protective for the structure and function of the glomerulus and maintains podocyte integrity during the development of diabetic nephropathy.

Intrauterine growth restriction promotes vascular remodelling following carotid artery ligation in rats

Epidemiological studies revealed an association between IUGR (intrauterine growth restriction) and an increased risk of developing CVDs (cardiovascular diseases), such as atherosclerosis or hypertension, in later life. Whether or not IUGR contributes to the development of atherosclerotic lesions, however, is unclear. We tested the hypothesis that IUGR aggravates experimentally induced vascular remodelling. IUGR was induced in rats by maternal protein restriction during pregnancy (8% protein diet). To detect possible differences in the development of vascular injury, a model of carotid artery ligation to induce vascular remodelling was applied in 8-week-old intrauterine-growth-restricted and control rat offspring. Histological and immunohistochemical analyses were performed in the ligated and non-ligated carotid arteries 8 weeks after ligation. IUGR alone neither caused overt histological changes nor significant dedifferentiation of VSMCs (vascular smooth muscle cells). After carotid artery ligation, however, neointima formation, media thickness and media/lumen ratio were significantly increased in rats after IUGR compared with controls. Moreover, dedifferentiation of VSMCs and collagen deposition in the media were more prominent in ligated carotids from rats after IUGR compared with ligated carotids from control rats. We conclude that IUGR aggravates atherosclerotic vascular remodelling induced by a second injury later in life.

Renal protection by low dose irbesartan in diabetic nephropathy is paralleled by a reduction of inflammation, not of endoplasmic reticulum stress

Diabetes can disrupt endoplasmic reticulum (ER) homeostasis which leads to ER stress. ER stress-induced renal apoptosis seems to be involved in the development of diabetic nephropathy. The present study was designed to investigate the contribution of reduced ER stress to the beneficial effects of an angiotensin receptor blocker. Insulin-dependent diabetes mellitus was induced by streptozotocin injections to hypertensive mRen2-transgenic rats. After 2weeks animals were treated with 0.7mg/kg/day irbesartan. Blood glucose, blood pressure and protein excretion were assessed. Expression of ER stress markers was measured by real-time PCR. Immunohistochemistry was performed to detect markers of ER stress, renal damage and infiltrating cells. Glomerulosclerosis and apoptosis were evaluated. Diabetic mRen2-transgenic rats developed renal injury with proteinuria, tubulointerstitial cell proliferation as well as glomerulosclerosis and podocyte injury. Moreover, an increase in inflammation, podocyte ER stress and apoptosis was detected. Irbesartan somewhat lowered blood pressure and reduced proteinuria, tubulointerstitial cell proliferation and glomerulosclerosis. Podocyte damage was ameliorated but markers of ER stress (calnexin, grp78) and apoptosis were not reduced by irbesartan. On the other hand, inflammatory cell infiltration in the tubulointerstitium and the glomerulus was significantly attenuated. We conclude that irbesartan reduced renal damage even in a very low dose. The beneficial effects of low dose irbesartan were paralleled by a reduction of blood pressure and inflammation but not by a reduction of ER stress and apoptosis. Thus, sustained endoplasmic reticulum stress in the kidney does not necessarily lead to increased inflammation and tubulointerstitial or glomerular injury.

Cullin 7 and Fbxw 8 expression in trophoblastic cells is regulated via oxygen tension: implications for intrauterine growth restriction?

Objective: The F-box protein Fbxw8 is a cofactor of Cullin 7 (Cul7), which regulates protein transfer to the proteasome and cell growth. Cul7 or Fbxw8 deficiency is associated with intrauterine growth restriction (IUGR) due to abnormal placental development leading to poor oxygen supply to the fetus. We studied the role of hypoxia for Fbxw8 and Cul7 expression in trophoblastic cells. Methods: Immunomagnetic bead-separated extravillous trophoblast (EVT) and villous trophoblast (VT) and trophoblast cell lines were incubated with 1 or 8% O2. Fbxw8 and Cul7 expression was determined in IUGR versus matched control placentas. Results: Fbxw8 was expressed uniformly in trophoblasts, whereas Cul7 expression was most prominent in trophoblast cell lines. Hypoxia reduced expression of Cul7 and Fbxw8 in all trophoblastic cells, except for villous trophoblasts. In vivo, Cul7 and Fbxw8 were detected in syncytiotrophoblast cells, VT, and EVT cells. Although no significant changes in expression levels of Fbxw8 or Cul7 were noted in IUGR compared with control placentas, Fbxw8 expression correlated negatively with gestational age in the control, but not in the IUGR group. Conclusion: Fbxw8 and Cul7 expression reveals a complex regulation in trophoblastic cells. Our findings suggest that dysregulation of Cul7 and Fbxw8 expression might affect trophoblast turnover in IUGR.