Cytokine accumulation in osteitis fibrosa of renal osteodystrophy

Bone marrow fibrosis occurs in association with a number of pathological states. Despite the extensive fibrosis that sometimes characterizes renal osteodystrophy, little is known about the factors that contribute to marrow accumulation of fibrous tissue. Because circulating cytokines are elevated in uremia, possibly in response to elevated parathyroid hormone levels, we have examined bone biopsies from 21 patients with end-stage renal disease and secondary hyperparathyroidism. Bone sections were stained with antibodies to human interleukin-1alpha (IL-1alpha), IL-6, IL-11, tumor necrosis factor-alpha (TNF-alpha) and transforming growth factor-ß (TGF-ß) using an undecalcified plastic embedding method. Intense staining for IL-1alpha, IL-6, TNF-alpha and TGF-ß was evident within the fibrotic tissue of the bone marrow while minimal IL-11 was detected. The extent of cytokine deposition corresponded to the severity of fibrosis, suggesting their possible involvement in the local regulation of the fibrotic response. Because immunoreactive TGF-ß and IL-6 were also detected in osteoblasts and osteocytes, we conclude that selective cytokine accumulation may have a role in modulating bone and marrow cell function in parathyroid-mediated uremic bone disease.

Chronic experimental myocardial infarction produces antinatriuresis by a renal nerve-dependent mechanism

The present study focused on the role of sympathetic renal nerve activity, in mediating congestive heart failure-induced sodium retention following experimental chronic myocardial infarction. Groups of male Wistar rats (240-260 g) were studied: sham-operated coronary ligation (CON3W, N = 11), coronary ligation and sham-operated renal denervation (INF3W, N = 19), 3 weeks of coronary ligation and sympathetic renal nerve denervation (INF3WDX, N = 6), sham-operated coronary ligation (N = 7), and 16 weeks of coronary ligation (INF16W, N = 7). An acute experimental protocol was used in which the volume overload (VO; 5% of body weight) was applied for 30 min after the equilibration period of continuous iv infusion of saline. Compared to control levels, VO produced an increase (P < 0.01, ANOVA) in urine flow rate (UFR; 570%) and urinary sodium excretion (USE; 1117%) in CON3W. VO induced a smaller increase (P < 0.01) in USE (684%) in INF3W. A similar response was also observed in INF16W. In INF3WDX, VO produced an immediate and large increase (P < 0.01) in UFR (547%) and USE (1211%). Similarly, in INF3W VO increased (P < 0.01) UFR (394%) and USE (894%). Compared with INF3W, VO induced a higher (P < 0.01) USE in INF3WDX, whose values were similar to those for CON3W. These results suggest that renal sympathetic activity may be involved in sodium retention induced by congestive heart failure. This premise is supported by the observation that in bilaterally renal denervated INF3WDX rats myocardial infarction was unable to reduce volume expansion-induced natriuresis. However, the mechanism involved in urinary volume regulation seems to be insensitive to the factors that alter natriuresis.

The role of stress-activated protein kinase signaling in renal pathophysiology

Two major stress-activated protein kinases are the p38 mitogen-activated protein kinase (MAPK) and the c-Jun amino terminal kinase (JNK). p38 and JNK are widely expressed in different cell types in various tissues and can be activated by a diverse range of stimuli. Signaling through p38 and JNK is critical for embryonic development. In adult kidney, p38 and JNK signaling is evident in a restricted pattern suggesting a normal physiological role. Marked activation of both p38 and JNK pathways occurs in human renal disease, including glomerulonephritis, diabetic nephropathy and acute renal failure. Administration of small molecule inhibitors of p38 and JNK has been shown to provide protection from renal injury in different types of experimental kidney disease through inhibition of renal inflammation, fibrosis, and apoptosis. In particular, a role for JNK signaling has been identified in macrophage activation resulting in up-regulation of pro-inflammatory mediators and the induction of renal injury. The ability to provide renal protection by blocking either p38 or JNK indicates a lack of redundancy for these two signaling pathways despite their activation by common stimuli. Therefore, the stress-activated protein kinases, p38 and JNK, are promising candidates for therapeutic intervention in human renal diseases.

Collagen XVIII/endostatin expression in experimental endotoxemic acute renal failure

Acute renal failure (ARF) is a frequent complication of Gram-negative sepsis, with a high risk of mortality. Lipopolysaccharide (LPS)-induced ARF is associated with hemodynamic changes that are strongly influenced by the overproduction of nitric oxide (NO) through the cytokine-mediated up-regulation of inducible NO synthase. LPS-induced reductions in systemic vascular resistance paradoxically culminate in renal vasoconstriction. Collagen XVIII is an important component of the extracellular matrix expressed in basement membranes. Its degradation by matrix metalloproteases, cathepsins and elastases results in the formation of endostatin, claimed to have antiangiogenic activity and to be a prominent vasorelaxing agent. We evaluated the expression of endostatin/collagen XVIII in an endotoxemic ARF model. ARF was induced in C57BL/6 mice by intraperitoneal injection of LPS (10 mg/kg) followed by sacrifice 4 and 12 h later. Kidney tissue was the source of RNA and protein and the subject of histological analysis. As early as 4 h after LPS administration, blood urea, creatinine and NO levels were significantly increased compared to control. Endostatin/collagen XVIII mRNA levels were 0.71 times lower than sham-inoculated mice 4 h after LPS inoculation, returning to normal levels 12 h after LPS inoculation. Immunohistological examination revealed that acute injury caused by LPS leads to an increase of endostatin basement membrane staining in association with the decrease of CD31 endothelial basement membrane staining. These results indicate that in the early phase of endotoxemic ARF the endostatin levels were not regulated by gene expression, but by the metabolism of collagen XVIII.

Maternal undernutrition and the offspring kidney: from fetal to adult life

Maternal dietary protein restriction during pregnancy is associated with low fetal birth weight and leads to renal morphological and physiological changes. Different mechanisms can contribute to this phenotype: exposure to fetal glucocorticoid, alterations in the components of the renin-angiotensin system, apoptosis, and DNA methylation. A low-protein diet during gestation decreases the activity of placental 11ß-hydroxysteroid dehydrogenase, exposing the fetus to glucocorticoids and resetting the hypothalamic-pituitary-adrenal axis in the offspring. The abnormal function/expression of type 1 (AT1R) or type 2 (AT2R) AngII receptors during any period of life may be the consequence or cause of renal adaptation. AT1R is up-regulated, compared with control, on the first day after birth of offspring born to low-protein diet mothers, but this protein appears to be down-regulated by 12 days of age and thereafter. In these offspring, AT2R expression differs from control at 1 day of age, but is also down-regulated thereafter, with low nephron numbers at all ages: from the fetal period, at the end of nephron formation, and during adulthood. However, during adulthood, the glomerular filtration rate is not altered, due to glomerulus and podocyte hypertrophy. Kidney tubule transporters are regulated by physiological mechanisms; Na+/K+-ATPase is inhibited by AngII and, in this model, the down-regulated AngII receptors fail to inhibit Na+/K+-ATPase, leading to increased Na+ reabsorption, contributing to the hypertensive status. We also considered the modulation of pro-apoptotic and anti-apoptotic factors during nephrogenesis, since organogenesis depends upon a tight balance between proliferation, differentiation and cell death.

Plasma concentrations and placental immunostaining of interleukin-10 and tumornecrosis factor-α as predictors of alterations in the embryo-fetal organism and the placental development of diabetic rats

Interleukin-10 (IL-10) appears to be the key cytokine for the maintenance of pregnancy and inhibits the secretion of inflammatory cytokines such as tumor necrosis factor-α (TNF-α). However, there are no studies evaluating the profile of these cytokines in diabetic rat models. Thus, our aim was to analyze IL-10 and TNF-α immunostaining in placental tissue and their respective concentrations in maternal plasma during pregnancy in diabetic rats in order to determine whether these cytokines can be used as predictors of alterations in the embryo-fetal organism and in placental development. These parameters were evaluated in non-diabetic (control; N = 15) and Wistar rats with streptozotocin (STZ)-induced diabetes (N = 15). At term, the dams (100 days of life) were killed under anesthesia and plasma and placental samples were collected for IL-10 and TNF-α determinations by ELISA and immunohistochemistry, respectively. The reproductive performance was analyzed. Plasma IL-10 concentrations were reduced in STZ rats compared to controls (7.6 ± 4.5 vs 20.9 ± 8.1 pg/mL). The placental scores of immunostaining intensity did not differ between groups (P > 0.05). Prevalence analysis showed that the IL-10 expression followed TNF-α expression, showing a balance between them. STZ rats also presented impaired reproductive performance and reduced plasma IL-10 levels related to damage during early embryonic development. However, the increased placental IL-10 as a compensatory mechanism for the deficit of maternal regulation permitted embryo development. Therefore, the data suggest that IL-10 can be used as a predictor of changes in the embryo-fetal organism and in placental development in pregnant diabetic rats.

The role of oxytocin in cardiovascular regulation

Studies of body volume expansion have indicated that lesions of the anteroventral third ventricle and median eminence block the release of atrial natriuretic peptide (ANP) into the circulation. Detailed analysis of the lesions showed that activation of oxytocin (OT)-ergic neurons is responsible for ANP release, and it has become clear that activation of neuronal circuitry elicits OT secretion into the circulation, activating atrial OT receptors and ANP release from the heart. Subsequently, we have uncovered the entire functional OT system in the rat and the human heart. An abundance of OT has been observed in the early development of the fetal heart, and the capacity of OT to generate cardiomyocytes (CMs) has been demonstrated in various types of stem cells. OT treatment of mesenchymal stem cells stimulates paracrine factors beneficial for cardioprotection. Cardiovascular actions of OT include: i) lowering blood pressure, ii) negative inotropic and chronotropic effects, iii) parasympathetic neuromodulation, iv) vasodilatation, v) anti-inflammatory activity, vi) antioxidant activity, and vii) metabolic effects. OT actions are mediated by nitric oxide and ANP. The beneficial actions of OT may include the increase in glucose uptake by CMs and stem cells, reduction in CM hypertrophy, oxidative stress, and mitochondrial protection of several cell types. In experimentally induced myocardial infarction in rats, continuous in vivo OT delivery improves cardiac healing and cardiac work, reduces inflammation, and stimulates angiogenesis. Because OT plays anti-inflammatory and cardioprotective roles and improves vascular and metabolic functions, it demonstrates potential for therapeutic use in various pathologic conditions.

Pkd1 transgenic mice: Adult model of polycystic kidney disease with extrarenal and renal phenotypes

While high levels of Pkd1 expression are detected in tissues of patients with autosomal dominant polycystic kidney disease (ADPKD), it is unclear whether enhanced expression could be a pathogenetic mechanism for this systemic disorder. Three transgenic mouse lines were generated from a Pkd1-BAC modified by introducing a silent tag via homologous recombination to target a sustained wild type genomic Pkd1 expression within the native tissue and temporal regulation. These mice specifically overexpressed the Pkd1 transgene in extrarenal and renal tissues from approximately 2- to 15-fold over Pkd1 endogenous levels in a copy-dependent manner. All transgenic mice reproducibly developed tubular and glomerular cysts leading to renal insufficiency. Interestingly, Pkd1(TAG) mice also exhibited renal fibrosis and calcium deposits in papilla reminiscent of nephrolithiasis as frequently observed in ADPKD. Similar to human ADPKD, these mice consistently displayed hepatic fibrosis and approximately 15% intrahepatic cysts of the bile ducts affecting females preferentially. Moreover, a significant proportion of mice developed cardiac anomalies with severe left ventricular hypertrophy, marked aortic arch distention and/or valvular stenosis and calcification that had profound functional impact. Of significance, Pkd1(TAG) mice displayed occasional cerebral lesions with evidence of ruptured and unruptured cerebral aneurysms. This Pkd1(TAG) mouse model demonstrates that overexpression of wildtype Pkd1 can trigger the typical adult renal and extrarenal phenotypes resembling human ADPKD.

Superoxide dismutase functional regulation in neonatal hypoxia

Hypoxia is one of the major causes of damage to the fetal and neonatal brain and cardiac functions. in earlier studies we have reported the brain damage caused by hypoxia and resusciation with oxygen and epinephrine and have found that glucose treatment to hypoxic rats and hypoxic rats treated with oxygen shows a reversal of brain damage. during this study the findings may have clinical significance in the proper management of heart and brain functions.

Prevalencia de insuficiencia renal crónica en niños con displasia renal multiquística, Fundación Cardioinfantil de Bogotá

Introducción: La displasia renal multiquistica es una variante de displasia renal, anomalía congénita frecuente del tracto urinario, con una prevalencia del 2.9 - 50 % de insuficiencia renal crónica; frecuentemente asociada a otras malformaciones urinarias, sin datos en bogotá sobre prevalencia y comportamiento clínico. Objetivo: Evaluar la prevalencia de insuficiencia renal crónica en niños con displasia renal multiquistica valorados en consulta de nefrología en Fundación Cardioinfantil, instituto de cardiología de Bogotá. Metodología: Estudio de corte transversal, en niños con displasia renal multiquistica, confirmado por ecografía, valorados en consulta de Nefrología Pediátrica en los últimos diez años. Se realizó un análisis descriptivo de las variables, cálculos de prevalencia de Insuficiencia renal crónica. Resultados: Se revisó información de 70 pacientes, encontrando una prevalencia de IRC de 22.85% (IC 95 % 13.0 %-35.1 %); mayor frecuencia mujeres 12.85 %; 14.28% con otras malformaciones renales; 5.71 % en involución parcial, 4.28% en pacientes con involución completa del tamaño del riñón displásico. Se encontró 31.4% proteinuria; 22.8 % hiperfiltración; 4.28% hipertrofia compensadora del riñón sano; 24.2% involución parcial, 31.4 % involución completa del tamaño renal; frecuencia de HTA de 7,1% (IC95% 1%-9%). El 87.14% tuvo diagnóstico prenatal (IC 95% 81.0%-96.0%). Discusión: La prevalencia se encuentra dentro de los rangos de la literatura mundial, mayor a la colombiana y suramericana, predominando en pacientes con otras malformaciones renales asociadas, con mayor prevalencia de hipertensión arterial, que requiere estudios multicéntricos para determinar causalidad o presencia de otros factores.

Heat shock protein 27 is the major differentially phosphorylated protein involved in renal epithelial cellular stress response and controls focal adhesion organization and apoptosis

We used two-dimensional difference gel electrophoresis to determine early changes in the stress-response pathways that precede focal adhesion disorganization linked to the onset of apoptosis of renal epithelial cells. Treatment of LLC-PK1 cells with the model nephrotoxicant 1,2-(dichlorovinyl)-L-cysteine (DCVC) resulted in a >1.5-fold up- and down-regulation of 14 and 9 proteins, respectively, preceding the onset of apoptosis. Proteins included those involved in metabolism, i.e. aconitase and pyruvate dehydrogenase, and those related to stress responses and cytoskeletal reorganization, i.e. cofilin, Hsp27, and alpha-b-crystallin. The most prominent changes were found for Hsp27, which was related to a pI shift in association with an altered phosphorylation status of serine residue 82. Although both p38 and JNK were activated by DCVC, only inhibition of p38 with SB203580 reduced Hsp27 phosphorylation, which was associated with accelerated reorganization of focal adhesions, cell detachment, and apoptosis. In contrast, inhibition of JNK with SP600125 maintained cell adhesion as well as protection against apoptosis. Active JNK co-localized at focal adhesions after DCVC treatment in a FAK-dependent manner. Inhibition of active JNK localization at focal adhesions did not prevent DCVC-induced phosphorylation of Hsp27. Overexpression of a phosphorylation-defective mutant Hsp27 acted as a dominant negative and accelerated the DCVC-induced changes in the focal adhesions as well as the onset of apoptosis. Our data fit a model whereby early p38 activation results in a rapid phosphorylation of Hsp27, a requirement for proper maintenance of cell adhesion, thus suppressing renal epithelial cell apoptosis.

Role of gamma-MSH peptides in the regulation of adrenal steroidogenesis

Alpha-, beta- and gamma-melanocyte stimulating hormones (MSHs) are peptides derived from the ACTH precursor, pro-opiomelanocortin. All three peptides have been highly conserved throughout evolution but their exact biological function in mammals is still largely obscure. In recent years, there has been a surge of interest in alpha-MSH and its role in the regulation of feeding. Gamma-MSH by contrast has been shown to be involved in the regulation of adrenal steroidogenesis and also has effects on the cardiovascular and renal systems. This review will provide an overview of the role that gamma-MSH peptides play in the regulation of adrenal steroidogenesis. (c) 2005 Elsevier Inc. All rights reserved.

Neurokinin B is a paracrine vasodilator in the human fetal placental circulation

Neurokinin (NK) B is a member of the tachykinin family of neurotransmitters, exerting hypotensive or hypertensive effects in the mammalian vasculature through synaptic release from peripheral neurons, according to either NK1 and NK2 or NK3 receptor subtype expression, respectively. There is recent evidence that NKB is expressed by the syncytiotrophoblast of the human placenta, an organ that is not innervated. We hypothesized that NKB is a paracrine modulator of tone in the fetal placental circulation. We tested this hypothesis using the in vitro perfused human placental cotyledon. Our data show that NKB is a dilator of the fetal vasculature, causing a maximal 25.1+/-4.5% (mean+/-SEM; n=5) decrease in fetal-side arterial hydrostatic pressure (5-muM NKB bolus; effective concentration in the circulation, 1.89 nM) after preconstriction with U-46619. RT-PCR demonstrated the presence of mRNA for NK1 and NK2 tachykinin receptors in the placenta. Using selective receptor antagonists, we found that NKB-induced vasodilation is through the NK1 receptor subtype. We found no evidence for the involvement of either nitric oxide or prostacyclin in this response. This study demonstrates a paracrine role for NKB in the regulation of fetal placental vascular tone.

Heat shock protein 27 is the major differentially phosphorylated protein involved in renal epithelial cellular stress response and controls focal adhesion organization and apoptosis

We used two-dimensional difference gel electrophoresis to determine early changes in the stress-response pathways that precede focal adhesion disorganization linked to the onset of apoptosis of renal epithelial cells. Treatment of LLC-PK1 cells with the model nephrotoxicant 1,2-(dichlorovinyl)-L-cysteine ( DCVC) resulted in a > 1.5-fold up- and down-regulation of 14 and 9 proteins, respectively, preceding the onset of apoptosis. Proteins included those involved in metabolism, i.e. aconitase and pyruvate dehydrogenase, and those related to stress responses and cytoskeletal reorganization, i.e. cofilin, Hsp27, and alpha-b-crystallin. The most prominent changes were found for Hsp27, which was related to a pI shift in association with an altered phosphorylation status of serine residue 82. Although both p38 and JNK were activated by DCVC, only inhibition of p38 with SB203580 reduced Hsp27 phosphorylation, which was associated with accelerated reorganization of focal adhesions, cell detachment, and apoptosis. In contrast, inhibition of JNK with SP600125 maintained cell adhesion as well as protection against apoptosis. Active JNK co-localized at focal adhesions after DCVC treatment in a FAK-dependent manner. Inhibition of active JNK localization at focal adhesions did not prevent DCVC-induced phosphorylation of Hsp27. Overexpression of a phosphorylation-defective mutant Hsp27 acted as a dominant negative and accelerated the DCVC-induced changes in the focal adhesions as well as the onset of apoptosis. Our data fit a model whereby early p38 activation results in a rapid phosphorylation of Hsp27, a requirement for proper maintenance of cell adhesion, thus suppressing renal epithelial cell apoptosis.

N-acetylcysteine protects against renal injury following bilateral ureteral obstruction

Background. Obstructive nephropathy decreases renal blood flow (RBF) and glomerular filtration rate (GFR), causing tubular abnormalities, such as urinary concentrating defect, as well as increasing oxidative stress. This study aimed to evaluate the effects of N-acetylcysteine (NAC) on renal function, as well as on the protein expression of aquaporin 2 (AQP2) and endothelial nitric oxide synthase (eNOS), after the relief of bilateral ureteral obstruction (BUO). Methods. Adult male Wistar rats were divided into four groups: sham (sham operated); sham operated + 440 mg/kg body weight (BW) of NAC daily in drinking water, started 2 days before and maintained until 48 h after the surgery; BUO (24-h BUO only); BUO + NAC-pre (24-h BUO plus 440 mg/kg BW of NAC daily in drinking water started 2 days before BUO); and BUO + NAC-post (24-h BUO plus 440 mg/kg BW of NAC daily in drinking water started on the day of BUO relief). Experiments were conducted 48 h after BUO relief. Results. Serum levels of thiobarbituric reactive substances, which are markers of lipid peroxidation, were significantly lower in NAC-treated rats than in the BUO group rats. The administration of NAC provided significant protection against post-BUO GFR drops and reductions in RBF. Renal cortices and BUO rats presented decreased eNOS protein expression of eNOS in the renal cortex of BUO group rats, whereas it was partially recovered in BUO + NAC-pre group rats. Urine osmolality was significantly lower in BUO rats than in sham group rats or NAC-treated rats, the last also presenting less interstitial fibrosis. Post-BUO downregulation of AQP2 protein expression was averted in the BUO + NAC-pre group rats. Conclusions. This study demonstrates that NAC administration ameliorates the renal function impairment observed 48 h after the relief of 24-h BUO. Oxidative stress is important for the suppression of GFR, RBF, tissue AQP2 and eNOS in the polyuric phase after the release of BUO.