Urinary podocyte markers in diabetic kidney disease

Podocytes are involved in maintaining kidney function and are a major focus of research on diabetic kidney disease (DKD). Urinary biomarkers derived from podocyte fragments and molecules have been proposed for the diagnosis and monitoring of DKD. Various methods have been used to detect intact podocytes and podocyte-derived microvesicles in urine, including centrifugation, visualization, and molecular quantification. Quantification of podocyte-specific protein targets and messenger RNA levels can be performed by Western blotting or enzyme-linked immunosorbent assay and quantitative polymerase chain reaction, respectively. At present, many of these techniques are expensive and labor-intensive, all limiting their widespread use in routine clinical tests. While the potential of urinary podocyte markers for monitoring and risk stratification of DKD has been explored, systematic studies and external validation are lacking in the current literature. Standardization and automation of laboratory methods should be a priority for future research, and the added value of these methods to routine clinical tests should be defined.

Visualization of choroidal vasculature in pigmented mouse eyes from experimental models of AMD

A variety of techniques exist to investigate retinal and choroidal vascular changes in experimental mouse models of human ocular diseases. While all have specific advantages, a method for evaluating the choroidal vasculature in pigmented mouse eyes has been more challenging especially for whole mount visualization and morphometric analysis. Here we report a simple, reliable technique involving bleaching pigment prior to immunostaining the vasculature in whole mounts of pigmented mouse choroids. Eyes from healthy adult pigmented C57BL/6J mice were used to establish the methodology. The retina and anterior segment were separated from the choroid. The choroid with retinal pigment epithelial cells (RPE) and sclera was soaked in 1% ethylenediaminetetraacetic acid (EDTA) to remove the RPE. Tissues were fixed in 2% paraformaldehyde (PFA) in phosphate-buffered saline (PBS). Choroids were subjected to melanin bleaching with 10% hydrogen peroxide (H2O2) at 55 °C for 90 min, washed in PBS and then immunostained with anti-podocalyxin antibody to label vascular endothelium followed by Cy3-AffiniPure donkey anti-goat IgG at 4 °C overnight. Images of immunostained bleached choroids were captured using a Zeiss 710 confocal microscope. In addition to control eyes, this method was used to analyze the choroids from subretinal sodium iodate (NaIO3) RPE atrophy and laser-induced choroidal neovascularization (CNV) mouse models. The H2O2 pretreatment effectively bleached the melanin, resulting in a transparent choroid. Immunolabeling with podocalyxin antibody following bleaching provided excellent visualization of choroidal vasculature in the flat perspective. In control choroids, the choriocapillaris (CC) displayed different anatomical patterns in peripapillary (PP), mid peripheral (MP) and far peripheral (FP) choroid. Morphometric analysis of the vascular area (VA) revealed that the CC was most dense in the PP region (87.4 ± 4.3% VA) and least dense in FP (79.9 ± 6.7% VA). CC diameters also varied depending on location from 11.4 ± 1.97 mm in PP to 15.1 ± 3.15 mm in FP. In the NaIO3-injected eyes, CC density was significantly reduced in the RPE atrophic regions (50.7 ± 5.8% VA in PP and 45.8 ± 6.17% VA in MP) compared to the far peripheral non-atrophic regions (82.8 ± 3.8% VA). CC diameters were significantly reduced in atrophic regions (6.35 ± 1.02 mm in PP and 6.5 ± 1.2 mm in MP) compared to non-atrophic regions (14.16 ± 2.12 mm). In the laser-induced CNV model, CNV area was 0.26 ± 0.09 mm2 and luminal diameters of CNV vessels were 4.7 ± 0.9 mm. Immunostaining on bleached choroids with anti-podocalyxin antibody provides a simple and reliable tool for visualizing normal and pathologic choroidal vasculature in pigmented mouse eyes for quantitative morphometric analysis. This method will be beneficial for examining and evaluating the effects of various treatment modalities on the choroidal vasculature in mouse models of ocular diseases such as age-related macular degeneration, and degenerative genetic diseases.

[Congenital Nephrotic Syndrome: Role of Podxl Gene]

In the last decades, our understanding of the genetic disorders of inherited podocytopathies has advanced immensely; this has been possible thanks to the development of next-generation sequencing technologies that offer the possibility to evaluate targeted genes at a lower cost than in the past. Identifying new genetic mutations has helped to recognize the key role of the podocyte in the health of the glomerular filter and to understand the mechanisms that regulate the cell biology and pathology of the podocyte. Here we describe a patient with congenital nephrotic syndrome due to a mutation in PODXL. This gene encodes podocalyxin, a podocyte-specific surface sialomucin known to maintain the characteristic architecture of the foot processes and the patency of the filtration slits.

Subcellular trafficking and transcytosis efficacy of different receptor types for therapeutic antibody delivery at the blood‒brain barrier

Here, we report an experimental setup to benchmark different receptors for targeted therapeutic antibody delivery at the blood-brain barrier. We used brain capillary endothelial-like cells derived from induced pluripotent stem cells (hiPSC-BECs) as a model system and compared them to colon epithelial Caco-2 cells. This approach helped to identify favourable receptors for transport into the cell layer itself or for directing transport for transcytosis across the cell layer. The sorting receptors transferrin receptor and sortilin were shown to be efficient as antibody cargo receptors for intracellular delivery to the cell layer. In contrast, the cell surface receptors CD133 and podocalyxin were identified as static and inefficient receptors for delivering cargo antibodies. Similar to in vivo studies, the hiPSC-BECs maintained detectable transcytotic transport via transferrin receptor, while transcytosis was restricted using sortilin as a cargo receptor. Based on these findings, we propose the application of sortilin as a cargo receptor for delivering therapeutic antibodies into the brain microvascular endothelium.

Functional annotation and enrichment analysis of differentially expressed serum proteins in patients with type 2 diabetes after dapagliflozin

BACKGROUND

Only 50% of patients with type 2 diabetes mellitus (T2DM) can control their blood glucose levels. Dapagliflozin is a selective inhibitor of sodium-glucose co-transporter 2 (SGLT-2) that improves the insulin sensitivity of the liver and peripheral tissues. Many studies confirmed that SGLT2 inhibitors reduce blood glucose and have multiple beneficial effects such as weight loss, lipid regulation, and kidney protection. Nevertheless, the mechanisms of the renal and cardiovascular protective effects of dapagliflozin from the perspective of differentially expressed proteins in the serum of T2DM patients have not been intensively explored so far.

AIM

To identify differentially expressed proteins associated with dapagliflozin treatment in patients with T2DM.

METHODS

Twenty T2DM patients [hemoglobin A1c (HbA1c) 7.0%-10.0%] were enrolled at The Affiliated Hospital of Inner Mongolia Medical University between January 1, 2017 and December 1, 2018. They received dapagliflozin (10 mg/d) for 3 mo, and the HbA1c < 7.0% target was achieved. The changes in clinical indexes were compared before and after treatments. Label-free quantitative proteomics was used to identify differentially expressed proteins using the serum samples of five patients. The identified differentially expressed proteins were analyzed using various bioinformatics tools.

RESULTS

Dapagliflozin significantly improved the clinical manifestation of the patients. There were 18 downregulated proteins and one upregulated protein in the serum samples of patients after dapagliflozin administration. Bioinformatics analyses, including subcellular localization, EuKaryotic Orthologous Groups, Gene Ontology, and Kyoto Encyclopedia of Genes and Genomes annotations, were used to profile the biological characteristics of the 19 differentially expressed proteins. Based on the literature and function enrichment analysis, two downregulated proteins, myeloperoxidase (MPO) and alpha II B integrin (ITGA2B), and one upregulated protein, podocalyxin (PCX), were selected for enzyme linked immunosorbent assay validation. These validated differentially expressed proteins had multiple correlations with clinical indexes, including HbAc1 and fasting C-peptide.

CONCLUSION

Dapagliflozin has hypoglycemic effects and regulates the serum expressions of MPO, ITGA2B, and PCX, possibly contributing to the effects of dapagliflozin on oxidative stress, insulin resistance, and lipid metabolism.

In vitro anti-motile effects of Rhoifolin, a flavonoid extracted from Callicarpa nudiflora on breast cancer cells via downregulating Podocalyxin-Ezrin interaction during Epithelial Mesenchymal Transition

BACKGROUND

Callicarpa nudiflora (C. nudiflora), which is a medical herb in genus of Callicarpa, widely grows in the southern part of China. Several investigations had shown that this herb exerts anti-tumor effects. Ezrin is an important membrane-cytoskeleton-binding protein. By organizing membrane proteins and orchestrating their signal transduction, Ezrin contributes to modulation of cytoskeleton rearrangement in cell motility.

PURPOSE

To investigate the anti-motile properties of Rhoifolin (RFL), a flavonoid from C. nudiflora, and to determine whether its effects are related to the inhibition on Podocalyxin (PODXL)-Ezrin signal transduction.

METHODS

To determine suitable concentration of RFL and exposure time on breast cancer cells, the effects of RFL on viability of breast cancer cells were evaluated by MTT assay. Then, the anti-migratory properties of RFL were determined by AP 48 chamber system and ORIS^TM cell migration assay. F-actin in MDA-MB-231 cells was visualized by Alexa Fluor™ 488 conjugated Phalloidin. Immunoprecipitation was involved to access the effects of RFL on the interaction between Ezrin and PODXL. In addition, several EMT markers, including E-cadherin, Vimentin, Snail and Slug, were measured by Western Blotting assay and cell immunofluorescent analysis. Finally, the effects of RFL on cell migration, expression of Ezrin and EMT markers were verified by small interfering RNA (siRNA) mediated gene silencing.

RESULTS

We showed here that treatments with 10 and 40 μM of RFL induced significant inhibitions on cell migration and alterations on the location and organization of actin cytoskeleton in breast cancer cells. Next, it was found that RFL suppressed Ezrin phosphorylation and consequent interaction with PODXL, significantly. Also, this compound showed an obvious inhibitory effect on TGF-β1-induced EMT in MDA-MB-231 cells. Furthermore, data from RNA interfering assay confirmed that the inhibitory effects of RFL on Ezrin was enhanced by the deletion of Ezrin.

CONCLUSION

RFL shows anti-motile properties on breast cancer cells, which is due to its potential to downregulate Podocalyxin-Ezrin interaction during Epithelial Mesenchymal Transition.

Urinary podocyte markers in kidney diseases

Podocytes play an important role in the maintenance of kidney function, and they are the primary focus of many kidney diseases. Podocyte injury results in the shedding of podocyte-derived cellular fragments and podocyte-specific molecular targets into the urine, which may serve as biomarkers of kidney diseases. Intact podocytes, either viable or dead, and podocyte-derived microvesicles could be quantified in the urine by various centrifugation, visualization and culture methods. Podocyte-specific protein targets from the nucleus, cytoplasm, slit-diaphragm, glomerular capillary basement membrane, and cytoskeleton, as well as their corresponding messenger RNA (mRNA), in the urine could be quantified by western blotting, ELISA, or quantitative polymerase chain reaction. Although some of these techniques may be expensive or labor-intensive at present, they may become widely available in the future because of the improvement in technology and automation. The application of urinary podocyte markers for the diagnosis and monitoring of various kidney diseases have been explored but the published data in this area are not sufficiently systematic and lack external validation. Further research should focus on standardizing, comparing, and automizing laboratory methods, as well as defining their added value to the routine clinical tests.

The role of serum podocalyxin levels in recurrent pregnancy loss

OBJECTIVE

To measure serum levels of podocalyxin (PODXL) in recurrent miscarriages as a marker of vascular endothelial dysfunction.

STUDY DESIGN

In this case-control study, women who were hospitalized for singleton first-trimester pregnancy terminations due to missed abortion, anembryonic pregnancy, and inevitable abortion were included. There were 24 patients who were admitted for the first pregnancy termination, 39 patients who were admitted for recurrent pregnancy loss (RPL), and 25 fetal cardiac activity positive patients as the control group. Demographic features, medical and obstetric histories were recorded. The measurements of serum PODXL were done by a human enzyme-linked immunosorbent assay kit.

RESULTS

Serum PODXL levels were found to be significantly higher in the RPL group than the control group and the first time miscarriage group (13.82 [10.09-113.54] vs. 11.78 [9.25-48.80], p = 0.016 and 13.82 [10.09-113.54] vs. 11.99 [8.20-20.47], p = 0.003; respectively). Serum PODXL levels were not statistically significantly different between the first miscarriage and the control group (p = 0.62). There were positive correlation between serum PODXL levels and the number of gravida and the number of miscarriages (r = 0.217, p = 0.042, and r = 0.291, p = 0.006; respectively).

CONCLUSION

Recurrent miscarriage patients had higher serum levels of PODXL than both normal pregnancies and first-time miscarriages. Our results suggest that maternal endothelial dysfunction might have a role in recurrent pregnancy losses.

A cancer-specific anti-podocalyxin monoclonal antibody (60-mG2a-f) exerts antitumor effects in mouse xenograft models of pancreatic carcinoma

Overexpression of podocalyxin (PODXL) is associated with progression, metastasis, and poor outcomes in several cancers. PODXL also plays an important role in the development of normal tissues. For antibody-based therapy to target PODXL-expressing cancers using monoclonal antibodies (mAbs), cancer-specificity is necessary to reduce the risk of adverse effects to normal tissues. In this study, we developed an anti-PODXL cancer-specific mAb (CasMab), named as PcMab-60 (IgM, kappa) by immunizing mice with soluble PODXL, which is overexpressed in LN229 glioblastoma cells. The PcMab-60 reacted with the PODXL-overexpressing LN229 (LN229/PODXL) cells and MIA PaCa-2 pancreatic cancer cells in flow cytometry but did not react with normal vascular endothelial cells (VECs), whereas one of non-CasMabs, PcMab-47 showed high reactivity for not only LN229/PODXL and MIA PaCa-2 cells but also VECs, indicating that PcMab-60 is a CasMab. Next, we engineered PcMab-60 into a mouse IgG_2a-type mAb, named as 60-mG_2a, to add antibody-dependent cellular cytotoxicity (ADCC). We further developed a core fucose-deficient type of 60-mG_2a, named as 60-mG_2a-f, to augment its ADCC activity. In vivo analysis revealed that 60-mG_2a-f exerted antitumor activity in MIA PaCa-2 xenograft models at a dose of 100 μg/mouse/week administered three times. These results suggested that 60-mG_2a-f could be useful for antibody-based therapy against PODXL-expressing pancreatic cancers.

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PODXL is associated with poor outcomes in several cancers.

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We developed an anti-PODXL cancer-specific mAb (PcMab-60).

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A core fucose-deficient IgG_2a type of PcMab-60 (60-mG_2a-f) exerted antitumor activity in MIA PaCa-2 xenograft models.

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60-mG_2a-f could be useful for antibody-based therapy against PODXL-expressing pancreatic cancers.

Monoclonal antibodies specific for podocalyxin expressed on human induced pluripotent stem cells

Human induced pluripotent stem cells (hiPSCs) are useful starting materials for the generation of cell therapy products, due to their pluripotency and ability to self-renew. Quality control of hiPSCs is extremely important in creating a stable supply of hPSC-derived products. Previously we identified an hiPSC-specific lectin probe, rBC2LCN, which binds specifically to α1,2-fucosylated glycan and recognizes podocalyxin (PODXL) as a glycoprotein ligand. In this study, we produced monoclonal antibodies (mAbs) specific for α1,2-fucosylated PODXL expressed on hiPSCs. PODXL was recombinantly expressed in fucosyltransferase 1 (FUT1)-transfected HEK293, followed by immunization into mice. Monoclonal antibodies, which bind to PODXL/FUT1-transfected cells, but not to cells transfected with only one of PODXL or FUT1, were screened by flow cytometry. The two mAbs generated (179-6B8C9 and 179-7E12E10), termed α1,2-fucosylated PODXL-specific mAbs (FpMabs), showed binding specificity to PODXL/FUT1-transfected cells. The FpMabs bound to hiPSCs but never to human adipose-derived mesenchymal stem cells, human dermal fibroblasts, or hiPSC-derived mesoderm. Altogether, FpMabs are highly specific probes for hiPSCs, which might be a powerful tool for the characterization of hiPSCs used in regenerative medicine.

Potential application of nanoemulsified garlic oil blend in mitigating the progression of type 2 diabetes-mediated nephropathy in Wistar rats

The renoprotective potential of nanoemulsified garlic oil blend (GNE) in alleviating the progressive stages of hyperlipidemia-mediated diabetic nephropathy was examined. The study was carried out in high fat-fed, streptozotocin-induced type 2 diabetic Wistar rats for five months. The diabetic rats showed a significant increase of area under the curve in OGTT (p < 0.01) and IPITT (p < 0.01), increased urinary albumin (p < 0.01), urinary microprotein (p < 0.001), total cholesterol (p < 0.01), triglycerides (p < 0.001) and LDL cholesterol (p < 0.001), with decreased serum albumin (p < 0.01), serum protein (p < 0.001) and HDL-cholesterol levels (p < 0.05) than the control rats. The histopathological analysis evidenced mesangial expansion and hypercellularity at the end of the first and third month, and glomerulosclerosis and tubular atrophy at the end of the fifth month in diabetic rats. Moreover, on disease progression, increase in urinary podocalyxin, NGAL and CD36 was observed, and the renal mRNA and protein expression of podocalyxin decreased significantly with a concomitant increase in NGAL and CD36 expression from first till fifth month end. The treatment with GNE (20 mg/kg) significantly ameliorated the serum albumin (p < 0.001) and urine albumin (p < 0.01) from the end of the third month with significant attenuation in the lipid profile than GO (20 mg/kg) or Ator (8 mg/kg). Moreover, GNE reverted the histopathological alterations and attenuated the aberrant mRNA, protein expression and urinary excretion level of renal CD36, podocalyxin and NGAL in diabetic rats from an early stage of disease till the end of the study period. This study demonstrated the enhanced efficacy of GO in nanoemulsified form in mitigating the progression of nephropathy in type 2 diabetic rats.

Mice lacking core 1-derived O-glycan in podocytes develop transient proteinuria, resulting in focal segmental glomerulosclerosis

The glomerular filtration barrier is composed of podocytes, glomerular basement membrane, and endothelial cells. Disruption of these structures causes several glomerular injuries, such as focal segmental glomerulosclerosis (FSGS). The surface of podocyte apical membranes is coated by negatively charged sialic acids on core 1-derived mucin-type O-glycans. Here, we aimed to investigate the physiological role of core 1-derived O-glycans in the podocytes using adult mice lacking podocyte-specific core 1-derived O-glycans (iPod-Cos). iPod-Cos mice exhibited early and transient proteinuria with foot process effacements and developed typical FSGS-like disease symptoms. To identify the key molecules responsible for the FSGS-like phenotype, we focused on podocalyxin and podoplanin, which possess mucin-type O-glycans. Expression and localization of podocalyxin did not change in iPod-Cos glomeruli. Besides, western blot analysis revealed significantly lower levels of intact podocalyxin in isolated glomeruli of iPod-Cos mice, and high levels of processed forms in iPod-Cos glomeruli, as compared to that in control glomeruli. Conversely, podoplanin mRNA, and protein levels were lower in iPod-Cos mice than in control mice. These results demonstrated that core 1-derived O-glycan on podocytes is required for normal glomerular filtration and may contribute to the stable expression of podocalyxin and podoplanin.

Keratan Sulphate in the Tumour Environment

Keratan sulphate (KS) is a bioactive glycosaminoglycan (GAG) of some complexity composed of the repeat disaccharide D-galactose β1→4 glycosidically linked to N-acetyl glucosamine. During the biosynthesis of KS, a family of glycosyltransferase and sulphotransferase enzymes act sequentially and in a coordinated fashion to add D-galactose (D-Gal) then N-acetyl glucosamine (GlcNAc) to a GlcNAc acceptor residue at the reducing terminus of a nascent KS chain to effect chain elongation. D-Gal and GlcNAc can both undergo sulphation at C6 but this occurs more frequently on GlcNAc than D-Gal. Sulphation along the developing KS chain is not uniform and contains regions of variable length where no sulphation occurs, regions which are monosulphated mainly on GlcNAc and further regions of high sulphation where both of the repeat disaccharides are sulphated. Each of these respective regions in the KS chain can be of variable length leading to KS complexity in terms of chain length and charge localization along the KS chain. Like other GAGs, it is these variably sulphated regions in KS which define its interactive properties with ligands such as growth factors, morphogens and cytokines and which determine the functional properties of tissues containing KS. Further adding to KS complexity is the identification of three different linkage structures in KS to asparagine (N-linked) or to threonine or serine residues (O-linked) in proteoglycan core proteins which has allowed the categorization of KS into three types, namely KS-I (corneal KS, N-linked), KS-II (skeletal KS, O-linked) or KS-III (brain KS, O-linked). KS-I to -III are also subject to variable addition of L-fucose and sialic acid groups. Furthermore, the GlcNAc residues of some members of the mucin-like glycoprotein family can also act as acceptor molecules for the addition of D-Gal and GlcNAc residues which can also be sulphated leading to small low sulphation glycoforms of KS. These differ from the more heavily sulphated KS chains found on proteoglycans. Like other GAGs, KS has evolved molecular recognition and information transfer properties over hundreds of millions of years of vertebrate and invertebrate evolution which equips them with cell mediatory properties in normal cellular processes and in aberrant pathological situations such as in tumourogenesis. Two KS-proteoglycans in particular, podocalyxin and lumican, are cell membrane, intracellular or stromal tissue-associated components with roles in the promotion or regulation of tumour development, mucin-like KS glycoproteins may also contribute to tumourogenesis. A greater understanding of the biology of KS may allow better methodology to be developed to more effectively combat tumourogenic processes.

Urinary podocyte-associated mRNA profile in Egyptian patients with diabetic nephropathy

INTRODUCTION

Podocyte injury and subsequent excretion in urine play a crucial role in the pathogenesis and progression of diabetic nephropathy (DN). Quantification of messenger RNA expression in urinary sediment by real-time PCR is emerging as a noninvasive method of screening DN-associated biomarkers. We aimed to study the expression of podocyte-associated genes in urinary sediment and their relation to disease severity in type 2 diabetic Egyptian patients with diabetic nephropathy.

METHOD

ology: Sixty patients with type 2 diabetes mellitus were recruited in addition to twenty non diabetic healthy volunteers. Relative mRNA abundance of nephrin, podocalyxin, and podocin were quantified, and correlations between target mRNAs and clinical parameters were examined.

RESULTS

The urinary mRNA levels of all genes studied were significantly higher in diabetics compared with controls (p < 0.001), and mRNA levels increased with DN progression. Urinary mRNA levels of all target genes positively correlated with both UAE and HbA_1c. The expression of nephrin, podocalyxin, and podocin mRNA correlated with serum creatinine {(r = 0.397, p value = 0.002), (r = 0.431, p value = 0.001), (r = 0.433, p value = 0.001) respectively}.

CONCLUSION

The urinary mRNA profiles of nephrin, podocalyxin, and podocin were found to increase with the progression of DN, which suggested that quantification of podocyte-associated molecules will be useful biomarkers of DN.

Evaluation of the urinary podocalyxin and nephrin excretion levels to determine a safe time interval between two sessions of SWL for renal stones: a non randomized exploratory study

OBJECTIVES

We aimed to evaluate the role of nephrin and podocalyxin in determining the intervals between shock wave lithotripsy (SWL) sessions and how soon the kidney damage was recovered.

METHODS

This work was a prospective study that included 30 patients with unilateral kidney stones. The patients' midflow urine samples were collected before SWL and 1 h, 1 day and 1 week after the procedure. Nephrin and podocalyxin levels in the urine samples were measured by the enzyme-linked immunosorbent assay method.

RESULTS

Among the 30 patients who underwent SWL, 19 were males and 11 were females. The mean age of the SWL group was 34.7 ± 13.2. Both biomarkers did not correlate with age, creatinine values, body mass index, stone side, stone size, energy, frequency and shock numbers. Nephrin and podocalyxin levels were significantly higher at the pre-SWL point (p < 0.05). After the procedure, a significant decrease was observed in both biomarker levels (p < 0.05). At the end of first day, these levels started to increase progressively up to the end of the first week (p  > 0.05).

CONCLUSIONS

Nephrin and podocalyxin may help to determine early period kidney damage associated with SWL. Post-SWL podocalyxin and nephrin values may be used to determine the interval between SWL sessions.

Podocyte Injury in Autosomal Dominant Polycystic Kidney Disease

BACKGROUND/AIMS

Autosomal dominant polycystic kidney disease (ADPKD) is a tubulointerstitial disease. Different degrees of glomerular affection in ADPKD may affect the further course of disease in which it may hypothetically be secondary to the result of glomerular involvement causing podocyte injury. Our aim was to compare urinary excretion of podocin and podocalyxin, which are biomarkers of podocyte injury, and to assess their relationship with proteinuria and renal function in ADPKD.

METHODS

Fifty-six patients with ADPKD and 28 volunteers were enrolled to study. Podocin, podocalyxin protein levels, and proteinuria were measured in urine. Patients were categorized based on their estimated glomerular filtration rate (eGFR).

RESULTS

Patients with ADPKD had higher podocin and podocalyxin levels compared to the control group. The levels of podocin and podocalyxin were higher in ADPKD patients both with eGFR ≥60 mL/min/1.73 m2 and with eGFR <60 mL/min/1.73 m2 than in controls. The levels of podocin and podocalyxin were higher in ADPKD patients with eGFR <60 mL/min/1.73 m2 than in ADPKD patients with eGFR ≥60 mL/min/1.73 m2. Podocin and podocalyxin were negatively correlated with eGFR and positively correlated with urine protein to creatinine ratio in ADPKD patients.

CONCLUSION

Urine biomarkers of podocytes injury were significantly higher in ADPKD patients even in the early stage of the disease than in the control group. It should be clarified whether these biomarkers can provide new prognostic parameters for disease surveillance.

Immunofluorescence staining of WT-1/Podocalyxin on Mouse kidney sections

In glomerular diseases, podocytes are one type of cells involved in dysfunction of glomerular filtration. In these conditions, podocyte proteins expression change. Therefore, immunofluorescent staining of podocytes can be performed to visualize podocyte localization of proteins of interest. In this protocol, we detail a method to stain podocytes with a specific marker WT-1 (Wilms Tumor-1) for "in situ" podocyte analysis by immunofluorescent microscopy, more informative technique than other techniques (as Western blot).

Tandem mass spectrometry analysis of urinary podocalyxin and podocin in the investigation of podocyturia in women with preeclampsia and Fabry disease patients

BACKGROUND

Podocytes are highly differentiated visceral cells, and several related specific proteins, such as podocalyxin and podocin are potential tools for the evaluation of podocyturia. However, precise quantitation of podocyturia-related proteins is complex and often unreliable.

METHOD

A reversed-phase ultra-performance liquid chromatography coupled to tandem mass spectrometry method was developed and validated to quantify podocalyxin and podocin levels in urine supernatant by using specific cleavable peptides and standards. Urine samples from women with normotensive or hypertensive pregnancies, gestational diabetes and preeclampsia, as well as treated and untreated Fabry patients, and gender-matched controls were investigated.

RESULTS

The multiplex analysis shows that podocalyxin levels were higher than podocin levels in patients, the former being particularly higher in pregnant women. Women with preeclampsia had abnormal urine levels of both proteins with a higher sensitivity for podocalyxin. Slightly increased levels of podocin were also observed in Fabry males, while both proteins were increased in untreated Fabry females. Correlations were established between podocalyxin and podocin levels and clinical parameters associated with Fabry disease and preeclampsia.

CONCLUSIONS

This methodology makes possible the precise, simultaneous and reliable analysis of podocalyxin and podocin levels, and offers a valuable tool for the evaluation of podocyturia.

Podocalyxin is crucial for the growth of oral squamous cell carcinoma cell line HSC-2

Oral cancers constitute approximately 2% of all cancers, with the most common histological type being oral squamous cell carcinoma (OSCC), representing 90% of oral cancers. Although diagnostic technologies and therapeutic techniques have progressed, the survival rate of patients with OSCC is still 60%, whereas the incidence rate has increased. Podocalyxin (PODXL) is a highly glycosylated type I transmembrane protein that is detected in normal tissues such as heart, breast, and pancreas as well as in many cancers, including lung, renal, breast, colorectal, and oral cancers. This glycoprotein is associated with the progression, metastasis, and poor outcomes of oral cancers. PODXL overexpression was strongly detected using our previously established anti-PODXL monoclonal antibody (mAb), PcMab-47, and its mouse IgG_2a-type, 47-mG_2a. In previous studies, we also generated PODXL-knock out (PODXL-KO) cell lines using SAS OSCC cell lines, in order to investigate the function of PODXL in the proliferation of oral cancer cells. The growth of SAS/PODXL-KO cell lines was observed to be lower than that of parental SAS cells. For this study, PODXL-KO OSCC cell lines were generated using HSC-2 cells, and the role of PODXL in the growth of OSCC cell lines in vitro was assessed. Decreased growth was observed for HSC-2/PODXL-KO cells compared with HSC-2 parental cells. The influence of PODXL on tumor growth of OSCC was also investigated in vivo, and both the tumor volume and the tumor weight were observed to be significantly lower for HSC-2/PODXL-KO than that for HSC-2 parental cells. These results, taken together, indicate that PODXL plays an important role in tumor growth, both in vitro and in vivo.

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PODXL-knock out cell lines were established using HSC-2.

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The growth of HSC-2/PODXL-KO cells were lower than that of parental HSC-2.

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Tumor volumes of HSC-2/PODXL-KO cells were lower than that of HSC-2.

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PODXL has an important role in tumor growth in vitro and in vivo.

Determination of critical epitope of PcMab-47 against human podocalyxin

Podocalyxin (PODXL) is a type I transmembrane protein, which is highly glycosylated. PODXL is expressed in some types of human cancer tissues including oral, breast, and lung cancer tissues and may promote tumor growth, invasion, and metastasis. We previously produced PcMab-47, a novel anti-PODXL monoclonal antibody (mAb) which reacts with endogenous PODXL-expressing cancer cell lines and normal cells independently of glycosylation in Western blot, flow cytometry, and immunohistochemical analysis. In this study, we used enzyme-linked immunosorbent assay (ELISA), flow cytometry, and immunohistochemical analysis to determine the epitope of PcMab-47. The minimum epitope of PcMab-47 was found to be Asp207, His208, Leu209, and Met210. A blocking peptide containing this minimum epitope completely neutralized PcMab-47 reaction against oral cancer cells by flow cytometry and immunohistochemical analysis. These findings could lead to the production of more functional anti-PODXL mAbs, which are advantageous for antitumor activities.

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PODXL is involved in cancer growth, invasion, and metastasis.

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PcMab-47 mAb against PODXL shows high ADCC/CDC and antitumor activities.

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PcMab-47 epitope was determined to be Asp207, His208, Leu209, and Met210.

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A blocking peptide completely neutralized PcMab-47 reaction by FCM and IHC.

Leukocyte-endothelial cell interaction is enhanced in podocalyxin-deficient mice

The highly sialoglycosylated extracellular domain of podocalyxin (Podxl) is a constituent of the endothelial glycocalyx of most blood vessels but it is unknown if Podxl plays a prominent role in the function of the glycocalyx as a regulator of leukocyte-endothelial adhesion. We have recently found that mice lacking Podxl in the vascular endothelium develop histological lesions compatible with severe vasculitis resulting in organ failure and premature death. In this work, we show that these mice have an increased quantity of resident leukocytes within the peritoneal cavity in both basal and inflammatory conditions. Adhesion of macrophagic cells to lung endothelial cells from Podxl-deficient mice was increased under inflammatory stimuli. Both, chemokine binding and chemokine-mediated adhesion of immune cells were significantly higher in Podxl-deficient endothelial cells. Moreover, glycocalyx function assessed by measuring the anticoagulant capacity of endothelial cell monolayers to inactivate thrombin was significantly altered in the absence of Podxl. Overall, the results suggest that Podxl is an essential component of the glycocalyx and has an important so far unknown role in preventing leukocyte-endothelial cell adhesion under resting and inflammatory conditions.

Podocalyxin as a major pluripotent marker and novel keratan sulfate proteoglycan in human embryonic and induced pluripotent stem cells

Podocalyxin (PC) was first identified as a heavily sialylated transmembrane protein of glomerular podocytes. Recent studies suggest that PC is a remarkable glycoconjugate that acts as a universal glyco-carrier. The glycoforms of PC are responsible for multiple functions in normal tissue, human cancer cells, human embryonic stem cells (hESCs), and human induced pluripotent stem cells (hiPSCs). PC is employed as a major pluripotent marker of hESCs and hiPSCs. Among the general antibodies for human PC, TRA-1-60 and TRA-1-81 recognize the keratan sulfate (KS)-related structures. Therefore, It is worthwhile to summarize the outstanding chemical characteristic of PC, including the KS-related structures. Here, we review the glycoforms of PC and discuss the potential of PC as a novel KS proteoglycan in undifferentiated hESCs and hiPSCs.

Urinary podocalyxin as a possible novel marker of intrauterine nephrogenesis and extrauterine podocyte injury

BACKGROUND

The number of nephrons at birth is determined during fetal development and is modulated thereafter by postnatal podocyte injury. Hyperfiltration, caused by a reduced number of nephrons, is a risk factor for chronic kidney disease. It is therefore important to monitor the formation of nephrons.

METHODS

Urine samples were collected from infants within 1-2 days of birth, with follow-up sampling for preterm infants at 37-39 weeks of corrected age. Urinary levels of podocalyxin (PCX), β2-microglobulin (β2MG), N-acetyl-ß-D-glucosaminidase (NAG), total protein (TP), microalbumin (mAlb) and creatinine were measured and the relationship between these markers evaluated.

RESULTS

Seventy-nine neonates were enrolled in this study. Urinary levels of PCX at birth were higher than normal adult reference values, with levels increasing up to a gestational age of 36 weeks (p = 0.0242). At 37-39 weeks corrected age, urinary levels of PCX decreased to adult levels. The levels of PCX in the urine at birth were not correlated to urinary levels of β2MG, NAG, TP and mAlb.

CONCLUSIONS

An increased urinary level of PCX may be a marker of both active nephron formation and podocyte injury sustained at birth. As such, changes in urinary levels of PCX are likely to reflect adaptation of renal function to the extra-uterine environment.

Gene-Edited Human Kidney Organoids Reveal Mechanisms of Disease in Podocyte Development

A critical event during kidney organogenesis is the differentiation of podocytes, specialized epithelial cells that filter blood plasma to form urine. Podocytes derived from human pluripotent stem cells (hPSC-podocytes) have recently been generated in nephron-like kidney organoids, but the developmental stage of these cells and their capacity to reveal disease mechanisms remains unclear. Here, we show that hPSC-podocytes phenocopy mammalian podocytes at the capillary loop stage (CLS), recapitulating key features of ultrastructure, gene expression, and mutant phenotype. hPSC-podocytes in vitro progressively establish junction-rich basal membranes (nephrin⁺ podocin⁺ ZO-1⁺ ) and microvillus-rich apical membranes (podocalyxin⁺ ), similar to CLS podocytes in vivo. Ultrastructural, biophysical, and transcriptomic analysis of podocalyxin-knockout hPSCs and derived podocytes, generated using CRISPR/Cas9, reveals defects in the assembly of microvilli and lateral spaces between developing podocytes, resulting in failed junctional migration. These defects are phenocopied in CLS glomeruli of podocalyxin-deficient mice, which cannot produce urine, thereby demonstrating that podocalyxin has a conserved and essential role in mammalian podocyte maturation. Defining the maturity of hPSC-podocytes and their capacity to reveal and recapitulate pathophysiological mechanisms establishes a powerful framework for studying human kidney disease and regeneration. Stem Cells 2017;35:2366-2378.

Value of immunohistochemical expression of podocalyxin in active lupus nephritis

Podocalyxin is an electronegative sialoglycoprotein that prevents the podocyte foot process from collapsing. The aim of this study was to detect an association between the glomerular immunohistochemical (IHC) expression of podocalyxin and the degree of podocyte effacement detected by electron microscopy, and to evaluate the role of podocalyxin IHC expression as a novel marker for disease activity in lupus nephritis (LN).

METHODS

Thirty-two renal biopsies of active lupus nephritis patients were studied. Clinical assessment by the systemic lupus activity measure (SLAM-R) score and laboratory data were included [serum creatinine, 24-h urinary protein, antinuclear antibodies (ANA), anti-double-strand DNA antibodies (anti-dsDNA), C3 and C4]. Light (L/M) and electron microscopic (E/M) examination was conducted. Podocyte loss was evaluated by immunohistochemistry with monoclonal anti-podocalyxin antibodies by means of a semiquantitative score that was graded from 0 to 4+ according to the percentage of glomerular involvement.

RESULTS

22 cases (68.8%) with LN class IV, 6 (18.8%) with class III and 4 (12.5%) with class V. The mean age was (25.41±10.13) years. There was a significant negative correlation between IHC podocalyxin score and LN class, and NIH activity parameters such as leukocyte infiltration, endocapillary proliferation, fibrinoid necrosis and cellular crescent and disease activity index but not chronicity index. There was a highly significant negative correlation between IHC podocalyxin and podocyte effacement by E/M (rs=-0.903, P=0.000), and E/M immune deposits (r=-0.53, P=0.001), and a significant association with degree of proteinuria, ANA and SLAM score (P<0.05).

CONCLUSIONS

Podocyte loss indicated by podocalyxin immunohistochemical expression reflects the degree of activity and severity of LN and the degree of podocyte effacement by E/M.

Podocalyxin as a major pluripotent marker and novel keratan sulfate proteoglycan in human embryonic and induced pluripotent stem cells

Podocalyxin (PC) was first identified as a heavily sialylated transmembrane protein of glomerular podocytes. Recent studies suggest that PC is a remarkable glycoconjugate that acts as a universal glyco-carrier. The glycoforms of PC are responsible for multiple functions in normal tissue, human cancer cells, human embryonic stem cells (hESCs), and human induced pluripotent stem cells (hiPSCs). PC is employed as a major pluripotent marker of hESCs and hiPSCs. Among the general antibodies for human PC, TRA-1-60 and TRA-1-81 recognize the keratan sulfate (KS)-related structures. Therefore, It is worthwhile to summarize the outstanding chemical characteristic of PC, including the KS-related structures. Here, we review the glycoforms of PC and discuss the potential of PC as a novel KS proteoglycan in undifferentiated hESCs and hiPSCs.

Role of CD34 family members in lumen formation in the developing kidney

Previous studies have shown CD34 family member Podocalyxin is required for epithelial lumen formation in vitro. We demonstrate that Endoglycan, a CD34 family member with homology to Podocalyxin, is produced prior to lumen formation in developing nephrons. Endoglycan localizes to Rab11-containing vesicles in nephron progenitors, and then relocalizes to the apical surface as progenitors epithelialize. Once an apical/luminal surface is formed, Endoglycan (and the actin-binding protein Ezrin) localize to large, intraluminal structures that may be vesicles/exosomes. We generated mice lacking Endoglycan and found mutants had timely initiation of lumen formation and continuous lumens, similar to controls. Mice with conditional deletion of both Endoglycan and Podocalyxin in developing nephrons also had normal tubular lumens. Despite this, Endoglycan/Podocalyxin is required for apical recruitment of the adaptor protein NHERF1, but not Ezrin, in podocyte precursors, a subset of the epithelia. In summary, while CD34 family members appear dispensable for lumen formation, our data identify Endoglycan as a novel pre-luminal marker and suggest lumen formation occurs via vesicular trafficking of apical cargo that includes Endoglycan.

Characterization of glycoproteins expressing the blood group H type 1 epitope on human induced pluripotent stem (hiPS) cells

Recently, we established two mouse monoclonal antibodies (R-10G and R-17F). The R-17F antibody (IgG1 subtype) exhibited a strong cytotoxic effect on hiPS/ES cells. The R-17F antigen isolated from a total lipid extract of hiPS (Tic) cells was identified as LNFP I (Fucα1-2Galβ1-3GlcNAcβ1-3Galβ1-4Glc). In the present study, R-17F binding proteins were isolated from hiPS (Tic) cell lysates with an affinity column of R-17F. They gave one major R-17F positive band around 250 kDa, and several minor bands between 150 kDa and 25 kDa. The former band was identified as podocalyxin by LC/MS/MS after SDS-PAGE. Hapten inhibition studies on R-17F binding to R-17F column-purified proteins with various synthetic oligosaccharides revealed that the blood group H type 1 triaose structure (Fucα1-2Galβ1-3GlcNAc) was the predominant epitope on all the R-17F binding proteins. These bands disappeared completely on digestion with α1-2 fucosidase, but not with α1-3/4 fucosidase. Upon PNGase F digestion, the R-17F positive band around and above 250 kDa did not show any change, while the minor bands between 150 kDa and 25 kDa disappeared completely, suggesting that the epitope is expressed on N-glycans in the latter and probably on O-glycans in the former. These results, together with those obtained in our previous studies on R-10G (Kawabe et al. Glycobiology, 23, 322-336 (2013)), indicated that both R-10G and R-17F epitopes are carried on the same podocalyxin molecule. The R-17F epitopes on these glycoproteins expressed on hiPS cells could be associated with the molecular mechanism underlying the carbohydrate-mediated cytotoxic activity of R-17F.

Complex Polarity: Building Multicellular Tissues Through Apical Membrane Traffic

The formation of distinct subdomains of the cell surface is crucial for multicellular organism development. The most striking example of this is apical-basal polarization. What is much less appreciated is that underpinning an asymmetric cell surface is an equally dramatic intracellular endosome rearrangement. Here, we review the interplay between classical cell polarity proteins and membrane trafficking pathways, and discuss how this marriage gives rise to cell polarization. We focus on those mechanisms that regulate apical polarization, as this is providing a number of insights into how membrane traffic and polarity are regulated at the tissue level.

Loss of endothelial barrier integrity in mice with conditional ablation of podocalyxin (Podxl) in endothelial cells

Podocalyxin (Podxl) has an essential role in the development and function of the kidney glomerular filtration barrier. It is also expressed by vascular endothelia but perinatal lethality of podxl(-/-) mice has precluded understanding of its function in adult vascular endothelial cells (ECs). In this work, we show that conditional knockout mice with deletion of Podxl restricted to the vascular endothelium grow normally but most die spontaneously around three months of age. Histological analysis showed a nonspecific inflammatory infiltrate within the vessel wall frequently associated with degenerative changes, and involving vessels of different caliber in one or more organs. Podxl-deficient lung EC cultures exhibit increased permeability to dextran and macrophage transmigration. After thrombin stimulation, ECs lacking Podxl showed delayed recovery of VE-cadherin cell contacts, persistence of F-actin stress fibers, and sustained phosphorylation of the ERM complex and activation of RhoA, suggesting a failure in endothelial barrier stabilization. The results suggest that Podxl has an essential role in the regulation of endothelial permeability by influencing the mechanisms involved in the restoration of endothelial barrier integrity after injury.

Podocalyxin-like protein 1 functions as an immunomodulatory molecule in breast cancer cells

Podocalyxin-like protein 1 (PCLP1), a CD34-related sialomucin involved in the regulation of cellular morphology and adhesion, is expressed by a number of normal cells and various tumor cells. In breast malignancies PCLP1 overexpression has been associated with the most aggressive, metastatic cancers and poor prognosis. These observations suggest that PCLP1 expression could provide a mechanism to evade the immune response, thereby promoting metastatic progression of cancer. In the present work, we aimed to determine the effect of PCLP1 overexpressed in MCF7 breast cancer cells on natural killer (NK) cell cytotoxicity, dendritic cell maturation, and agonist-induced T cell proliferation. The results showed that PCLP1 expressed in MCF7 breast cancer cells confers resistance to NK cell-mediated cytolysis and impairs T cell proliferation. Furthermore, PCLP1 decreased the levels of NK cell activating receptors NKG2D, NKp30, NKp44, NKp46, DNAM-1, and CD16 on cell surface in a contact-dependent manner. Moreover, NK cells acquired PCLP1 from MCF7 cells by a process known as trogocytosis. These data reveal a new function of PCLP1 expressed on tumor cells as an immunomodulatory molecule, which may represent a mechanism to evade the immune response.

Urinary podocalyxin, the novel biomarker for detecting early renal change in obesity

BACKGROUND

The prevalence of obesity is increasing during the past decade along with obesity-related glomerulopathy (ORG), glomeruli injury due to the obesity. The major pathogenesis of ORG is the shedding of podocytes from the glomerular cell barrier into urine. Podocalyxin (PCX), a main surface antigen of podocyte, correlates well with glomerulosclerosis progression and glomerular injury severity, and might be a potential biomarker for early renal alteration in obesity. In addition, vascular endothelial growth factor (VEGF) and alpha-smooth muscle actin (α-SMA) also play a role in promoting glomerulosclerosis. The aim of this study was to explore whether obese subjects without other diseases excrete more PCX-positive (PCX+) cells than non-obese individuals, in comparison with urine protein-creatinine ratio (UPCR) and glomerular filtration rate (GFR) as traditional renal markers. Moreover, the effect of body mass index (BMI) on urinary VEGF, PCX or α-SMA positive cells was also investigated.

METHODS

Forty-eight obese and 13 non-obese adults were included. Exfoliated cells from fresh first void morning urine were harvested, stained with PCX, VEGF, and α-SMA antibody, and quantified by flow cytometry. Correlation between interested urinary biomarkers (cells positive for PCX, VEGF plus PCX and α-SMA), UPCR and GFR with BMI and metabolic risk factors were analyzed.

RESULTS

Obese patients had significantly higher PCX+ cells than non-obese [0.62 (0.00-13.13) vs. 0.15 (0.00-0.72) cells/ml × mg cr, p < 0.05]. There was no significant difference in GFR and UPCR between the groups. Of interest, BMI demonstrated a correlation with PCX+ cells (r = 0.343, p = 0.008) and cells positive for PCX plus VEGF (r = 0.374, p = 0.004).

CONCLUSION

Obese subjects without other diseases and with normal UPCR and GFR showed evidence of renal alteration through the detection of a higher number of PCX+ cells. Increasing BMI also resulted in higher number of PCX+ cells.

The alpha-lipoic acid decreases urinary podocalyxin excretion in type 2 diabetics by inhibiting oxidative stress in vivo

OBJECTIVE

To observe the effects of Alpha-lipoic acid (ALA) on oxidative stress (OS) in vivo and urinary podocalyxin (PCX, the glomerular podocyte marker protein) excretion in type 2 diabetics and explore its possible protective mechanisms on glomerular podocytes.

METHODS

Thirty-six type 2 diabetics were recruited as observation group and treated with ALA on the basis of initial therapy for six months, and 30 healthy subjects were selected as control group. FBG, HbA1c, serum glutathione peroxidase (SGSH-Px), superoxide dismutase (SSOD) activity, urinary malondialdehyde (UMDA), 8-hydroxy-deoxyguanosine (U8-OHdG), albumin (UALB), creatinine (UCr) and urinary PCX (UPCX) were determined at baseline and after six months' observation.

RESULTS

Compared with the control group, the ratios of UMDA/UCr (UMCR), U8-OHdG/UCr (U8CR), UALB/UCr (UACR) and UPCX/UCr (UPCR) increased markedly, SGSH-Px and SSOD decreased significantly in the diabetics (P<0.01); after sixth month treatment, the levels of UMCR, U8CR, UACR and UPCR reduced and SGSH-Px and SSOD increased markedly in the observation group (P<0.05) with no significant changes in FBG and HbA1c. UPCR had positive correlation with UACR, UMCR and U8CR (r=0.720, r=0.661, r=0.698, P<0.01), and negative correlation with SGSH-Px and SSOD in the diabetics (r=-0.608, r=-0.559, P<0.01).

CONCLUSION

ALA can provide some protection against glomerular podocyte injury in type 2 diabetics, which may be related partly to its effects in alleviating enhanced OS and strengthening antioxidant ability in vivo.

Expression of podocalyxin separates the hematopoietic and vascular potentials of mouse embryonic stem cell-derived mesoderm

In the mouse embryo and differentiating embryonic stem cells, the hematopoietic, endothelial, and cardiomyocyte lineages are derived from Flk1+ mesodermal progenitors. Here, we report that surface expression of Podocalyxin (Podxl), a member of the CD34 family of sialomucins, can be used to subdivide the Flk1+ cells in differentiating embryoid bodies at day 4.75 into populations that develop into distinct mesodermal lineages. Definitive hematopoietic potential was restricted to the Flk1+Podxl+ population, while the Flk1-negative Podxl+ population displayed only primitive erythroid potential. The Flk1+Podxl-negative population contained endothelial cells and cardiomyocyte potential. Podxl expression distinguishes Flk1+ mesoderm populations in mouse embryos at days 7.5, 8.5, and 9.5 and is a marker of progenitor stage primitive erythroblasts. These findings identify Podxl as a useful tool for separating distinct mesodermal lineages.

Mechanisms by which heme oxygenase rescue renal dysfunction in obesity

Obesity and excessive inflammation/oxidative stress are pathophysiological forces associated with kidney dysfunction. Although we recently showed that heme-oxygenase (HO) improves renal functions, the mechanisms are largely unclear. Moreover, the effects of the HO-system on podocyte cytoskeletal proteins like podocin, podocalyxin, CD2-associated-protein (CD2AP) and proteins of regeneration/repair like beta-catenin, Oct3/4, WT1 and Pax2 in renal tissue from normoglycemic obese Zucker-fatty rats (ZFs) have not been reported.

Treatment with hemin reduced renal histo-pathological lesions including glomerular-hypertrophy, tubular-cast, tubular-atrophy and mononuclear cell-infiltration in ZFs. These were associated with enhanced expression of beta-catenin, Oct3/4, WT1, Pax2 and nephrin, an essential transmembrane protein required for the formation of the scaffoldings of the podocyte slit-diaphragm, permitting the filtration of small ions, but not massive excretion of proteins, hence proteinuria. Besides nephrin, hemin also enhanced other important podocyte-regulators including, podocalyxin, podocin and CD2AP. Correspondingly, important markers of renal dysfunction such as albuminuria and proteinuria were reduced, while creatinine clearance increased, suggesting improved renal function in hemin-treated ZFs. The renoprotection by hemin was accompanied by the reduction of inflammatory/oxidative mediators including, macrophage-inflammatory-protein-1α, macrophage-chemoattractant-protein-1 and 8-isoprostane, whereas HO-1, HO-activity and the total-anti-oxidant-capacity increased. Contrarily, the HO-inhibitor, stannous-mesoporphyrin nullified the reno-protection by hemin.

Collectively, these data suggest that hemin ameliorates nephropathy by potentiating the expression of proteins of repair/regeneration, abating oxidative/inflammatory mediators, reducing renal histo-pathological lesions, while enhancing nephrin, podocin, podocalyxin, CD2AP and creatinine clearance, with corresponding reduction of albuminuria/proteinuria suggesting improved renal function in hemin-treated ZFs. Importantly, the concomitant potentiation regeneration proteins and podocyte cytoskeletal proteins are novel mechanisms by which hemin rescue nephropathy in obesity.

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Renal dysfunction is common in obesity.

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Novel mechanisms by which heme-oxygenase (HO) rescue kidney failure are unveiled.

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HO enhance podocyte cytoskeletal proteins like podocin, podocalyxin and CD2AP.

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HO enhance proteins of regeneration/repair like beta-catenin, Oct3/4, WT1 and Pax2.

Urinary podocalyxin as a marker of preeclampsia in a Hispanic population

BACKGROUND

Preeclampsia is associated with significant materno-fetal morbidity and mortality. Podocyturia due to podocyte damage seems to be associated with the disease. The objective of this study was to evaluate the usefulness of urinary podocalyxin as a marker of preeclampsia in a Hispanic population.

METHODS

63 patients were studied. 25 patients had preeclampsia/eclampsia (PE-E). 38 patients had normal pregnancies and served as control group. 24 hour proteinuria, urine protein/creatinine (UPC), urinary podocalyxin and perinatal outcomes were measured. A Podocalyxin ELISA test was used to detect podocyturia.

RESULTS

Mean age (years), mean±SD was 30.5±5.4 in normal patients vs 30.6±5.8 in PE-E, p=0.98. Median gestational age (weeks) was, 38 (range 21-42) for normal pregnancies and 36 (range 24-40) for patients with PE-E, <0.001. Urine podocalyxin/creatinine on admission (ng/mg), median [IQR] in normal patients was 55.9 [29.4, 74.9] vs 109.7 [63.8, 234.1] in PE-E, p=0.001. After adjusting for admission proteinuria, urinary podocalyxin remained independently associated with preeclampsia: OR=1.0040 (95% CI 1.0003-1.0078), p=0.03. There was low to moderate correlation between UPC and urinary podocalyxin, Spearman's =0.31, p=0.01. In PE-E, post-partum urine podocalyxin was lower, median [IQR]: 69.7 [32.7, 184.8] p=0.19 vs admission. There was a trend towards more podocyturia and proteinuria in patients with eclampsia, comparing to those with preeclampsia. There was no association observed between podocyturia and neonatal mortality, IUGR or Apgar scores.

CONCLUSIONS

Significantly higher levels of urinary podocalyxin are seen in preeclampsia/eclampsia. They tend to normalize after delivery.

Urinary podocalyxin positive-element occurs in the early stage of diabetic nephropathy and is correlated with a clinical diagnosis of diabetic nephropathy

AIMS

We tested whether urinary podocalyxin-positive element (PCX+EL) can be a marker of early stage of diabetic nephropathy (DN).

METHODS

DN patients (n=68) and health controls (n=28) were enrolled in this study. Patients were classified into three groups: normoalbuminuria, microalbuminuria and macroalbuminuria. Urinary PCX+EL, serum cystatin C (Scys C) and serum creatinine (SCr) were quantified, and correlations between urinary PCX+EL and urinary albumin, Scys C and SCr were examined. The comparison of diagnosis efficiency among urinary PCX+EL, Scys C and SCr was made by receiver operating characteristic (ROC) analysis.

RESULTS

Urinary PCX+EL, Scys C and SCr significantly increased in DN patients compared with controls. Urinary PCX+EL increased significantly in all three patients groups compared with controls. However, the concentration of Scys C and SCr did not increase in normoalbuminuria group. Urinary albumin, Scys C and SCr correlated with urinary PCX+EL. ROC curve analysis indicated that area under the curve (AUC) of urinary PCX+EL (0.966) is higher than that of Scys C (0.857) and SCr (0.726) for discriminating nephropathy between DN patients and controls.

CONCLUSION

Urinary PCX+EL may be a noninvasive marker for the early stage of DN.