The role of type I hypersensitivity reaction and IgE-mediated mast cell activation in acute interstitial nephritis.

BACKGROUND: Acute interstitial nephritis (AIN) presents with acute kidney injury, with evidence of interstitial inflammation and tubulitis on histology, and the presence of fever, rash, and eosinophiluria. Although the pathogenesis of this disease is not well understood, cell-mediated immunity is thought to play a major role. We hypothesized that IgE mediated mast cell activation is also involved in the pathogenesis of renal injury in AIN. METHODS: 28 patients, with biopsy proven AIN over a 5-year period, were included in this study. Clinical data, including renal outcomes and the etiologies of AIN, were evaluated in all patients. Available tissues (renal biopsy) from 26 of the patients were stained for ß-tryptase (marker for mast cell degranulation), IgE, IL-16, and CD3. A negative control for immunostaining was included. RESULTS: Samples from all 26 individuals stained positive for ß-tryptase (mean of 11.16 cells/high power field), IgE (mean average of 0.68 cells/HPF), IL-16 (28% of the interstitium), and CD3 (33% of the interstitium). Acute interstitial nephritis was due to medication in 73%, systemic disease in 15%, and unknown (idiopathic) in 12% of the cases. 86% of patients were treated with corticosteroids. 18% required acute inpatient dialysis, with 7% remaining on dialysis longterm. CONCLUSIONS: Our study suggests that IgE and mast cell activation may play a role in the pathogenesis of AIN.

Urinary podocyte excretion and proteinuria in patients treated with antivascular endothelial growth factor therapy for solid tumor malignancies.

BACKGROUND: Urinary podocyte excretion (podocyturia) may function as a more specific marker of ongoing glomerular damage. This study sought to analyze the relationship between proteinuria and podocyturia in cancer patients treated with antivascular endothelial growth factor (anti-VEGF) agents. METHODS: Thirty-seven patients treated with anti-VEGF medications were analyzed in a single-institution, cross-sectional study. Podocyte cultures were performed on random urine collections (50-100 ml), and podocytes were identified by positive podocin staining. The corresponding urine samples were analyzed for protein and creatinine (Cr) measurements. RESULTS: Proteinuria ≥0.5 g/g Cr was found in 30% of the patients (median, 0.12; interquartile range, 0.04-0.86), and 62% had podocyturia. There was a significant difference in the amount of podocyturia between patients with proteinuria ≥0.5 g/g Cr and those with a value <0.5 g/g Cr (median podocyturia, 1.08 cells/mg Cr, range, 0-14.55 vs. 0.03 cells/mg Cr, range, 0-1.64, respectively; p < 0.001). A statistically significant correlation was observed between the cumulative dose of bevacizumab and both proteinuria (r = 0.48, p = 0.004) and podocyturia (r = 0.34, p = 0.045) as well as between proteinuria and podocyturia (r = 0.63, p < 0.001), suggesting that these are mechanistically related. DISCUSSION: Ongoing podocyte loss may be mechanistically related to the onset and severity of proteinuria in patients treated with anti-VEGF agents.

Persistent urinary podocyte loss following preeclampsia may reflect subclinical renal injury.

OBJECTIVE: Studies have shown that podocyturia, i.e., urinary loss of viable podocytes (glomerular epithelial cells), is associated with proteinuria in preeclampsia. We postulated that urinary podocyte loss may persist after preeclamptic pregnancies, thus resulting in renal injury. This may lead to future chronic renal injury. In addition, we compared the postpartum levels of the angiogenic factors, which previously have been associated with preeclampsia, between normotensive versus preeclamptic pregnancies. STUDY DESIGN: The diagnosis of preeclampsia was confirmed using standard clinical criteria. Random blood and urine samples were obtained within 24 hours prior to delivery and 5 to 8 weeks postpartum. Urine sediments were cultured for 24 hours to select for viable cells and staining for podocin was used to identify podocytes. Serum samples were analyzed for the levels of angiogenic markers using ELISA (enzyme-linked immunosorbent assay) methodology. RESULTS: At delivery, preeclamptic patients (n = 10) had significantly higher proteinuria (p = 0.006) and podocyturia (p<0.001) than normotensive pregnant patients (n = 18). Postpartum proteinuria was similar between these two groups (p = 0.37), while podocyturia was present in 3 of 10 women with preeclampsia and in none of the normotensive controls (p = 0.037). Angiogenic marker levels, including placental growth factor, soluble vascular endothelial growth factor receptor fms-like tyrosine kinase receptor-1 and endoglin, were not significantly different between women with preeclampsia and women with a normotensive pregnancy, either at delivery or postpartum. CONCLUSION: Persistent urinary podocyte loss after preeclamptic pregnancies may constitute a marker of ongoing, subclinical renal injury.

Advances in the pathophysiology of pre-eclampsia and related podocyte injury.

Pre-eclampsia is a pregnancy-specific hypertensive disorder that may lead to serious maternal and fetal complications. It is a multisystem disease that is commonly, but not always, accompanied by proteinuria. Its cause(s) remain unknown, and delivery remains the only definitive treatment. It is increasingly recognized that many pathophysiological processes contribute to this syndrome, with different signaling pathways converging at the point of systemic endothelial dysfunction, hypertension, and proteinuria. Different animal models of pre-eclampsia have proven utility for specific aspects of pre-eclampsia research, and offer insights into pathophysiology and treatment possibilities. Therapeutic interventions that specifically target these pathways may optimize pre-eclampsia management and may improve fetal and maternal outcomes. In addition, recent findings regarding placental, endothelial, and podocyte pathophysiology in pre-eclampsia provide unique and exciting possibilities for improved diagnostic accuracy. Emerging evidence suggests that testing for urinary podocytes or their markers may facilitate the prediction and diagnosis of pre-eclampsia. In this review, we explore recent research regarding placental, endothelial, and podocyte pathophysiology. We further discuss new signaling and genetic pathways that may contribute to pre-eclampsia pathophysiology, emerging screening and diagnostic strategies, and potential targeted interventions.

Genome-wide methylation profiling demonstrates hypermethylation in maternal leukocyte DNA in preeclamptic compared to normotensive pregnancies.

OBJECTIVE: To compare genome-wide methylation profiles in maternal leukocyte DNA between normotensive and preeclamptic pregnant women at delivery. METHODS: Age, body mass index matched case-control comparison of methylation at 27,578 cytosine-- guanine sites in 14,495 genes in maternal leukocyte DNA in women with preeclampsia (PE; n = 14) and normotensive controls (n = 14). RESULTS: PE was associated with widespread differential methylation favoring hypermethylation. Pathway analysis identified the best matched process as a neuropeptide signaling pathway (p < 10(-5)); best matched disease as eclampsia (p < 9.97 × 10(-20)). Significantly differentially methylated genes (GRIN2b. GABRA1. PCDHB7, and BEX1) are associated with seizures. CONCLUSION: Altered maternal leukocyte DNA methylation is associated with PE at delivery, and differential methylation of certain neuronal genes may explain the risk for eclampsia.

Podocyturia predates proteinuria and clinical features of preeclampsia: longitudinal prospective study.

Podocyturia, the shedding of live podocytes, is present at delivery in women with preeclampsia. The aim of this study was to test whether podocyturia is present earlier in pregnancy and predicts for preeclampsia. We also aimed to compare test characteristics of podocyturia with those of angiogenic factors previously implicated in the pathogenesis of this disorder. We prospectively enrolled 315 women who provided blood and urine samples at the end of the second trimesters of their pregnancies (median, 27 gestational weeks) and within 24 hours of their deliveries (median, 39.5 gestational weeks). Blood samples were analyzed for angiogenic markers, including placental growth factor, the soluble receptor fms-like tyrosine kinase receptor-1 for vascular endothelial growth factor, and endoglin. The urine sediments were analyzed for podocytes, identified by staining for podocin after culturing the urinary sediments for 24 hours. This analysis included all women who developed preeclampsia (n=15), gestational hypertension (n=15), and a subsample of women who remained normotensive throughout pregnancy (n=44), matched for maternal age and number of previous pregnancies to those who developed preeclampsia. At the second trimester collection, all women who developed preeclampsia had podocyturia, compared with none of those who remained normotensive or were diagnosed with gestational hypertension. Podocyturia in the second trimester had a significantly greater sensitivity and specificity for the subsequent diagnosis of preeclampsia than any single angiogenic marker or a combination thereof. Screening for podocyturia at the end of the second trimester may allow for accurate identification of pregnant women at risk for preeclampsia.

Mass spectrometry as a novel method for detection of podocyturia in pre-eclampsia.

BACKGROUND: Podocyturia, i.e. urinary loss of viable podocytes, may serve as a diagnostic tool for pre-eclampsia and as a marker of active renal disease. The current method to detect podocyturia is technically complex, lengthy and requires a high level of expertise for interpretation. The aim of this study was to develop a new technique for the identification of urinary podocytes, based on the detection of podocyte-specific tryptic peptides by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS), which will provide an operator-independent and highly reproducible method. METHODS AND RESULTS: The diagnosis of pre-eclampsia was confirmed in the presence of hypertension (>140/90 mmHg) and proteinuria >0.3 g/24 h urine. The diagnosis of HELLP was confirmed based on the accepted clinical criteria of hemolysis, elevated liver enzymes and low platelet count. Random urine samples within 24 h prior to delivery were collected and centrifuged. One half of the sediment was cultured for 24 h to select for viable cells and then stained with a podocin antibody, followed by a secondary fluorescein isothiocyanate-labeled antibody to identify podocytes. The second half of the pellet was solubilized, digested and analyzed by LC-MS/MS using an internal standard. We have recruited 13 patients with pre-eclampsia and 6 patients with pre-eclampsia/HELLP syndrome. The presence of podocytes was confirmed in all patients by the podocyte culture method. In the respective samples, the presence of a podocin-specific tryptic peptide was confirmed with LC-MS/MS technology. CONCLUSION: The LC-MS/MS method is a reliable technology for the identification of urinary podocytes, based on the presence of podocyte-specific proteins in the urine.

Urinalysis is more specific and urinary neutrophil gelatinase-associated lipocalin is more sensitive for early detection of acute kidney injury.

BACKGROUND: Neutrophil gelatinase-associated lipocalin (NGAL) protein is a promising biomarker to detect acute kidney injury (AKI). Earlier detection of AKI could facilitate evaluation of novel therapeutic strategies. METHODS: Random and 24-h urine samples were prospectively obtained from 125 normal volunteers for analytic validation of a urinary enzyme-linked immunosorbent assay for NGAL. For clinical validation of the test, urine from 363 emergency department patients admitted to the hospital was obtained for NGAL enzyme-linked immunosorbent assay and urinalysis and AKI was determined by the use of Acute Kidney Injury Network (AKIN) criteria. RESULTS: NGAL was stable in urine for 7 days when ambient, 4 °C or frozen (-20 or -70 °C). The assay was linear between 0.24 and 10,000 ng/mL with a limit of quantitation of 0.24 ng/mL. Intra- and inter-assay precision were excellent (coefficient of variation <5%); however, urinary white blood cells were associated with increased NGAL levels. The 95th percentile reference value for NGAL in females is ≤ 65.0 and ≤ 23.4 ng/mL in males. Urinary NGAL levels increased with AKI stage but had only fair sensitivity (65%) and specificity (65%) to differentiate no AKI versus Stages 1, 2 or 3 (area under the curve 0.70). Urinalysis with microscopy was very specific (91%) but not very sensitive (22%) with an area under the curve of 0.57. CONCLUSIONS: NGAL can be reliably measured in clinical urine samples, although pyuria is an important potential confounder. In our cohort, increased urinary NGAL was associated with AKI by the AKIN criteria; however, the sensitivity and specificity were only fair, in part because patients with pre-renal causes are not excluded by AKIN criteria. Conversely, findings on microscopic urinalysis are very specific for AKI.

From placenta to podocyte: vascular and podocyte pathophysiology in preeclampsia.

Preeclampsia is a disorder of hypertension and proteinuria that affects 6 - 8% of normal pregnancies. Recent research has revealed many molecular mechanisms that may contribute to systemic endothelial dysfunction, glomerular capillary endotheliosis, dysregulation of the glomerular filtration apparatus, and podocyte loss. An ischemic placenta elaborates soluble FMS-like tyrosine kinase 1 (sFlt-1), a soluble receptor for vascular endothelial growth factor (VEGF). A variety of mediators, including nitric oxide, Angiotensin II receptor autoantibodies (AT1AA), and endothelin-1 may serve to maintain placental ischemia and systemic endothelial dysfunction. Endothelin-1 and decreased vascular endothelial growth factor may adversely affect overall expression and distribution of podocyte foot process proteins, leading to proteinuria. Podocyte derangements may lead to podocyte apoptosis and loss, as evidenced by the detection of live podocytes and podocyte products in the urine of preeclamptic women. In this review, we explore recent research elucidating the interactions of placenta, endothelium, and podocyte leading to the clinical syndrome of preeclampsia.

Normal early pregnancy: a transient state of epigenetic change favoring hypomethylation.

The objective of this study was to analyze genome-wide differential methylation patterns in maternal leukocyte DNA in early pregnant and non-pregnant states. This is an age and body mass index matched case-control study comparing the methylation patterns of 27,578 cytosine-guanine (CpG) sites in 14,495 genes in maternal leukocyte DNA in early pregnancy (n = 14), in the same women postpartum (n = 14), and in nulligravid women (n = 14) on a BeadChip platform. Transient widespread hypomethylation was found in early pregnancy as compared with the non-pregnant states. Methylation of nine genes was significantly different in early pregnancy compared with both postpartum and nulligravid states (< 10% False Discovery Rate). Early pregnancy may be characterized by widespread hypomethylation compared with non-pregnant states; there is no apparent permanent methylation imprint after a normal term gestation. Nine potential candidate genes were identified as differentially methylated in early pregnancy and may play a role in the maternal adaptation to pregnancy.

Induction therapy in renal transplant recipients: how convincing is the current evidence?

The goal of organ transplantation is to provide durable organ function while minimizing risks such as infection and cancer. Induction therapy in renal transplantation provides improved short- and long-term graft outcomes compared with placebo. Three agents are currently available and widely used in the US; rabbit anti-thymocyte globulin (rATG), basiliximab and alemtuzumab. These agents are all clinically effective in transplantation. In patients at high risk of rejection, graft outcomes are improved with the use of depleting agents, such as rATG or alemtuzumab, rather than basiliximab. Depleting agents are associated with more complications, such as infection and malignancy. The risk-benefit analysis for low-risk patients indicates that basiliximab may be the preferred agent in this population. Use of induction therapy, particularly with rATG, may not only allow for but also mandate reduction of maintenance immunosuppression. The mechanisms by which induction agents lead to improved clinical outcomes have not been elucidated. rATG and alemtuzumab lead to prompt and durable lymphocyte depletion, but many other mechanisms contribute to their suppression of alloimmunity. For instance, rATG contains antibodies specific for multiple adhesion molecules and even human leukocyte antigen, while CD52 (the target of alemtuzumab) is present on many antigen-presenting cells as well as lymphocytes. The manner in which the immune system recovers after induction may also aid in establishment of immune tolerance, with proliferation of suppressor T lymphocytes seen with rATG use. The various contributions of these mechanisms in achieving the goal of allograft tolerance are currently being investigated. The currently available data are of generally low quality, based on many small and often retrospective studies. Definitions of 'high risk' vary between studies, as do induction and maintenance dosing regimens. Standardization of definitions and establishment of large, prospective, multicentre trials would lead to a better understanding of the currently available agents and their best use in renal transplantation induction therapy.

Posterior reversible encephalopathy syndrome and eclampsia: pressing the case for more aggressive blood pressure control.

OBJECTIVE: To assess the prevalence, clinical presentations, and neuroimaging abnormalities in a series of patients treated for eclampsia at Mayo Clinic in Rochester, MN. PATIENTS AND METHODS: We reviewed the records of all pregnant patients diagnosed as having eclampsia at Mayo Clinic in Rochester, MN, between January 1, 2001, and December 31, 2008. All patients who underwent neuroimaging were identified, and all studies were reviewed by an independent neuroradiologist. Comparisons were made between groups who did and did not undergo imaging to identify differentiating clinical or laboratory variables. RESULTS: Thirteen cases of eclampsia were found, with neuroimaging studies available for 7: magnetic resonance imaging (n=6) and computed tomography (n=1). All 7 patients developed eclamptic seizures, and 2 of 7 patients had severe hypertension, with recorded systolic blood pressures exceeding 180 mm Hg. Neuroimaging showed characteristic changes of posterior reversible encephalopathy syndrome (PRES) in all patients. Follow-up imaging showed resolution in 2 of 3 patients; 1 patient had residual neuroimaging abnormalities. CONCLUSION: Our results suggest that the clinical syndrome of eclampsia is associated with an anatomical substrate that is recognizable by neuroimaging as PRES. The levels of blood pressure elevation are lower than those reported in cases of PRES because of hypertensive encephalopathy. Further studies are needed to determine whether more aggressive blood pressure control and early neuroimaging may have a role in the management of these patients.

Mammillothalamic tract lesions disrupt dead reckoning in the rat.

Debate surrounds the role of the limbic system structures' contribution to spatial orientation. The results from previous studies have supported a role for the mammillary bodies and their projections to the anterior thalamus in rapid encoding of relationships among environmental cues; however, this work is based on behavioral tasks in which environmental and self-movement cues could not be dissociated. The present study examines the effects of mammillothalamic tract lesions on spatial orientation in the food hoarding paradigm and the water maze. Although the food hoarding paradigm dissociates the use of environmental and self-movement cues, both sources of information are available to guide performance in the water maze. Mammillothalamic tract lesions selectively impaired performance on both tasks. These impairments are interpreted as providing further evidence for the role of limbic system structures in processing self-movement cues.

Pre-eclamptic pregnancies: an opportunity to identify women at risk for future cardiovascular disease.

Evaluation of: Bellamy L, Casas JP, Hingorani AD, Williams DJ: Pre-eclampsia and risk of cardiovascular disease and cancer in later life: systematic review and meta-analysis. Br. Med. J. 335(7627), 974 (2007). Evidence has emerged over the years suggesting that women who develop hypertensive pregnancy disorders, most notably pre-eclampsia, are at an increased risk for cardiovascular disease later in life. In this study, a systematic review and meta-analysis were performed, assessing the future risks of cardiovascular disease, cancer and all-cause mortality in women with a history of pre-eclampsia and eclampsia. Women with a history of pre-eclampsia or eclampsia, compared with women without such a history, had an increased risk for cardiovascular disease, including a fourfold increased risk for hypertension, a twofold increased risk for ischemic heart disease, stroke and deep venous thrombosis, and a 1.5-times higher all-cause mortality. The study suggests that affected women may be eligible for preventive therapies at an earlier age, especially if future studies establish the role of pre-eclampsia as an independent cardiovascular risk factor.

Organization of food protection behavior is differentially influenced by 192 IgG-saporin lesions of either the medial septum or the nucleus basalis magnocellularis.

Converging lines of evidence have supported a role for the nucleus basalis magnocellularis (NB) in attentional mechanisms; however, debate continues regarding the role of the medial septum in behavior (MS). Recent studies have supported a role for the septohippocampal system in the online processing of internally generated cues. The current study was designed to investigate a possible double dissociation in rat food protection behavior, a natural behavior that has been shown to depend on external and internal sources of information. The study examined the effects of intraparenchymal injections of 192 IgG-saporin into either the MS or NB on the organization of food protection behavior. NB cholinergic lesions reduced the number of successful food protection behaviors while sparing the temporal organization of food protection behavior. In contrast, MS cholinergic lesions disrupted the temporal organization of food protection behavior while sparing the ability to successfully protect food items. These observations are consistent with a double dissociation of NB and MS cholinergic systems' contributions to processing external and internal sources of information and provide further evidence for the septohippocampal system's involvement in processing internally generated cues.

Nogo-A inhibition induces recovery from neglect in rats.

Neglect is a complex human cognitive spatial disorder typically induced by damage to prefrontal or posterior parietal association cortices. Behavioral treatments for neglect rarely generalize outside of the therapeutic context or across tasks within the same therapeutic context. Recovery, when it occurs, is spontaneous over the course of weeks to months, but often it is incomplete. A number of studies have indicated that anti-Nogo-A antibodies can be used to enhance plasticity and behavioral recovery following damage to motor cortex, and spinal cord. In the present studies the anti-Nogo-A antibodies IN-1, 7B12, or 11C7 were applied intraventricularly to adult rats demonstrating severe neglect produced by unilateral medial agranular cortex lesions in rats. The three separate anti-Nogo-A antibody groups were treated immediately following the medial agranular cortex lesions. Each of the three antibodies induced dramatic significant behavioral recovery from neglect relative to controls. Severing the corpus callosum to destroy inputs from the contralesional hemisphere resulted in reinstatement of severe neglect, pointing to a possible role of interhemispheric mechanisms in behavioral recovery from neglect.

Hypertensive pregnancy disorders: current concepts.

Hypertensive pregnancy disorders complicate 10% of all pregnancies and cover a spectrum of conditions, namely preeclampsia, eclampsia, and chronic and gestational hypertension. Preeclampsia is a pregnancy-specific disorder clinically characterized by hypertension and proteinuria that occurs after 20 weeks of gestation. It remains a leading cause of both fetal and maternal morbidity and mortality worldwide. Traditionally, hypertensive pregnancy disorders were considered not to have any long-term impact on mothers' cardiovascular health; however, recent studies consistently have supported the role of hypertension in pregnancy as a risk factor for cardiovascular disease later in life. Therefore, improved screening, and preventive and treatment strategies may not only optimize management of hypertensive pregnancy disorders, but may have a long-term impact on women's cardiovascular events and outcomes years after the affected pregnancies. This article will provide a brief review of hypertensive pregnancy disorders and important recent discoveries regarding their pathogeneses, while focusing on current diagnostic and treatment strategies.

Urinary podocyte excretion as a marker for preeclampsia.

OBJECTIVE: The objective of this study was to examine whether podocyturia, which is the urinary excretion of viable podocytes (glomerular epithelial cells), is present in urinary sediments of patients with preeclampsia. We also aimed to compare the test characteristics of podocyturia to those angiogenic factors that have been shown to play an important role in the pathogenesis of preeclampsia (s-Flt-1, PlGF, and endoglin). STUDY DESIGN: Serum angiogenic factors were measured in 44 patients with preeclampsia and 23 normotensive control patients. In a patient subset (15 cases and 16 control patients), urinary proteinuria were identified and quantified on the basis of their expressions of podocyte-specific proteins. RESULTS: Urinary podocyte excretion occurred in all patients with preeclampsia. The positive predictive value for the diagnosis of preeclampsia was greater for podocyturia than for any of the measured angiogenic factors. CONCLUSION: Podocyturia is a highly sensitive and specific marker for preeclampsia. It may contribute to the development of proteinuria in preeclampsia.

Glomerular expression of nephrin and synaptopodin, but not podocin, is decreased in kidney sections from women with preeclampsia.

BACKGROUND: Preeclampsia is a pregnancy-specific disorder characterized by hypertension and proteinuria. In other disease states, proteinuria has been linked to altered expressions of podocyte foot-process proteins, but this has not been studied in women with preeclampsia. We sought to test the hypothesis that proteinuria in preeclampsia is associated with dysregulated expression of the podocyte cytoskeleton and/or tight junction proteins. METHODS: Renal tissue was obtained from autopsy material from seven women who had severe preeclampsia during the second half of their pregnancies up to 48 h after delivery, and who subsequently died. As controls, we used autopsy material from two women who died accidentally during the second half of their otherwise normal pregnancies. Immunohistochemical stains for nephrin, synaptopodin and podocin were performed on representative sections prepared from paraffin-embedded material. RESULTS: Expression of both nephrin and synaptopodin was markedly decreased in preeclamptic compared with control kidney sections. By contrast, both cases and controls demonstrated strong staining for podocin. CONCLUSIONS: We conclude that down-regulation of nephrin and synaptopodin is associated with proteinuria in women with preeclampsia. Recent studies have demonstrated that soluble vascular endothelial growth factor receptor 1 (sFlt-1) levels are elevated in preeclampsia compared with normal pregnancy. Studies in mice have shown that sFlt-1 may play a role in inducing proteinuria by neutralizing vascular endothelial growth factor (VEGF) and suppressing nephrin. Proteinuria and elevations of sFlt-1 in preeclampsia are temporally related, further supporting a possible role of sFlt-1 in the dysregulation of podocyte foot-process proteins.