Heterogeneous distribution of glycoconjugates in human kidney tubules

Lectin Histochemistry of the Normal Feline Kidney

Lectins have a strict binding specificity to carbohydrate moieties of cellular components, and can thus indicate changes in the glycosylation of cells in diseases. However, lectin-binding patterns in nephron segments of feline kidneys have not been fully surveyed. The present study reported lectin-binding patterns in normal feline kidneys by histochemical investigations of eight commercially available lectin detection kits. Kidneys from four normal cats (intact males, 23-27 months old) were fixed in 4% paraformaldehyde, and embedded in paraffin; lectin histochemistry was performed for WGA, s-WGA, RCA-I, ConA, PNA, SBA, DBA, and UEA-I lectins. WGA, RCA, and ConA binding was observed from Bowman's capsule to the collecting ducts, while only WGA was detected in the glomerular capillary. s-WGA was observed from the proximal tubules to the collecting ducts, showing discriminative heterogeneous binding. PNA and SBA were detected in the distal nephrons, such as the thin limbs of the loops of Henle, distal tubules, and collecting ducts. UEA-I binding was observed in the thick ascending limbs of the loops of Henle, especially in the macula densa regions. DBA lectin showed no positive labeling in nephrons. The observed binding patterns may prove beneficial for the analysis of changes in glycosylation in feline kidney diseases.

Enhanced metanephric specification to functional proximal tubule enables toxicity screening and infectious disease modelling in kidney organoids

While pluripotent stem cell-derived kidney organoids are now being used to model renal disease, the proximal nephron remains immature with limited evidence for key functional solute channels. This may reflect early mispatterning of the nephrogenic mesenchyme and/or insufficient maturation. Here we show that enhanced specification to metanephric nephron progenitors results in elongated and radially aligned proximalised nephrons with distinct S1 - S3 proximal tubule cell types. Such PT-enhanced organoids possess improved albumin and organic cation uptake, appropriate KIM-1 upregulation in response to cisplatin, and improved expression of SARS-CoV-2 entry factors resulting in increased viral replication. The striking proximo-distal orientation of nephrons resulted from localized WNT antagonism originating from the organoid stromal core. PT-enhanced organoids represent an improved model to study inherited and acquired proximal tubular disease as well as drug and viral responses.

Enhanced metanephric specification to functional proximal tubule enables toxicity screening and infectious disease modelling in kidney organoids

While pluripotent stem cell-derived kidney organoids are now being used to model renal disease, the proximal nephron remains immature with limited evidence for key functional solute channels. This may reflect early mispatterning of the nephrogenic mesenchyme and/or insufficient maturation. Here we show that enhanced specification to metanephric nephron progenitors results in elongated and radially aligned proximalised nephrons with distinct S1 - S3 proximal tubule cell types. Such PT-enhanced organoids possess improved albumin and organic cation uptake, appropriate KIM-1 upregulation in response to cisplatin, and improved expression of SARS-CoV-2 entry factors resulting in increased viral replication. The striking proximo-distal orientation of nephrons resulted from localized WNT antagonism originating from the organoid stromal core. PT-enhanced organoids represent an improved model to study inherited and acquired proximal tubular disease as well as drug and viral responses.

Human iPSC-derived renal organoids engineered to report oxidative stress can predict drug-induced toxicity

Advances in regenerative medicine have led to the construction of many types of organoids, which reproduce important aspects of endogenous organs but may be limited or disorganized in nature. While their usefulness for restoring function remains unclear, they have undoubted usefulness in research, diagnostics, and toxicology. In toxicology, there is an urgent need for better models for human kidneys. We used human iPS-cell (hiPSC)-derived renal organoids to identify HMOX1 as a useful marker of toxic stress via the oxidative stress pathway, and then constructed an HMOX1 reporter in hiPSCs. We used two forms of hiPSC-derived HMOX1-reporter renal organoids to probe their ability to detect nephrotoxicants in a panel of blind-coded compounds. Our results highlight the potential usefulness, and some limitations, of HMOX1-reporter renal organoids as screening tools. The results may guide development of similar stress-reporting organoid assays for other stem-cell-derived organs and tissues.

Hnf4a Is Required for the Development of Cdh6-Expressing Progenitors into Proximal Tubules in the Mouse Kidney

BACKGROUND

Hepatocyte NF 4α (Hnf4a) is a major regulator of renal proximal tubule (PT) development. In humans, a mutation in HNF4A impairs PT functions and is associated with Fanconi renotubular syndrome (FRTS). In mice, mosaic deletion of Hnf4a in the developing kidney reduces the population of PT cells, leading to FRTS-like symptoms. The molecular mechanisms underlying the role of Hnf4a in PT development remain unclear.

METHODS

The gene deletion tool Osr2Cre removed Hnf4a in developing nephrons in mice, generating a novel model for FRTS. Immunofluorescence analysis characterized the mutant phenotype, and lineage analysis tested whether Cadherin-6 (Cdh6)-expressing cells are PT progenitors. Genome-wide mapping of Hnf4a binding sites and differential gene analysis of Hnf4a mutant kidneys identified direct target genes of Hnf4a.

RESULTS

Deletion of Hnf4a with Osr2Cre led to the complete loss of mature PT cells, lethal to the Hnf4a mutant mice. Cdh6^high, lotus tetragonolobus lectin-low (LTL^low) cells serve as PT progenitors and demonstrate higher proliferation than Cdh6^low, LTL^high differentiated PT cells. Additionally, Hnf4a is required for PT progenitors to differentiate into mature PT cells. Genomic analyses revealed that Hnf4a directly regulates the expression of genes involved in transmembrane transport and metabolism.

CONCLUSIONS

Hnf4a promotes the differentiation of PT progenitors into mature PT cells by regulating the expression of genes associated with reabsorption, the major function of PT cells.

Urinary extracellular vesicles: Origin, role as intercellular messengers and biomarkers; efficient sorting and potential treatment options

Urinary extracellular vesicles (uEVs) are a heterogenous group of vesicles consisting mainly of microvesicles and exosomes that originate predominantly (99.96%) from kidney, the urinary tract epithelium and the male reproductive tract. Secreted EVs contain molecular cargo from parental cells and provide an attractive source for biomarkers, a potential readout of physiological and pathophysiological mechanisms, and events associated with the urinary system. uEVs are readily enriched and isolated from urine samples and we review 6 standard methods that allow for downstream analysis of the uEV cargo. Although the use of uEVs as a surrogate readout for physiological changes in tissue protein levels is widespread, the protein abundance in uEVs is affected significantly by mechanisms that regulate protein sorting and secretion in uEVs. Data suggest that baseline kidney tissue and uEV levels of apical membrane-associated electrolyte transport proteins are not directly related in human patients. Recent evidence indicates that EVs may contribute to physiological and pathophysiological intercellular signalling and EVs confer protection against renal ischemia-reperfusion injury. The therapeutic use of EVs as information carriers has mainly been explored in vitro and a major hurdle lies in the translation of the in vitro findings into an in vivo setting. Thus, the EV research field is moving from a technical focus to a more physiological focus, allowing for a deeper understanding of human physiology, development of diagnostic tools and potential treatment strategies for precision medicine.

Serum D-serine accumulation after proximal renal tubular damage involves neutral amino acid transporter Asc-1

Chiral separation has revealed enantio-specific changes in blood and urinary levels of amino acids in kidney diseases. Blood D-/L-serine ratio has been identified to have a correlation with creatinine-based kidney function. However, the mechanism of distinctive behavior in serine enantiomers is not well understood. This study was performed to investigate the role of renal tubules in derangement of serine enantiomers using a mouse model of cisplatin-induced tubular injury. Cisplatin treatment resulted in tubular damage histologically restricted to the proximal tubules and showed a significant increase of serum D-/L-serine ratio with positive correlations to serum creatinine and blood urine nitrogen (BUN). The increased D-/L-serine ratio did not associate with activity of a D-serine degrading enzyme, D-amino acid oxidase, in the kidney. Screening transcriptions of neutral amino acid transporters revealed that Asc-1, found in renal tubules and collecting ducts, was significantly increased after cisplatin-treatment, which correlates with serum D-serine increase. In vitro study using a kidney cell line showed that Asc-1 is induced by cisplatin and mediated influx of D-serine preferably to L-serine. Collectively, these results suggest that cisplatin-induced damage of proximal tubules accompanies Asc-1 induction in tubules and collecting ducts and leads to serum D-serine accumulation.

Fundamental insights into autosomal dominant polycystic kidney disease from human-based cell models

Several animal- and human-derived models are used in autosomal dominant polycystic kidney disease (ADPKD) research to gain insight in the disease mechanism. However, a consistent correlation between animal and human ADPKD models is lacking. Therefore, established human-derived models are relevant to affirm research results and translate findings into a clinical set-up. In this review, we give an extensive overview of the existing human-based cell models. We discuss their source (urine, nephrectomy and stem cell), immortalisation procedures, genetic engineering, kidney segmental origin and characterisation with nephron segment markers. We summarise the most studied pathways and lessons learned from these different ADPKD models. Finally, we issue recommendations for the derivation of human-derived cell lines and for experimental set-ups with these cell lines.

Hnf4a deletion in the mouse kidney phenocopies Fanconi renotubular syndrome

Different nephron tubule segments perform distinct physiological functions, collectively acting as a blood filtration unit. Dysfunction of the proximal tubule segment can lead to Fanconi renotubular syndrome (FRTS), with major symptoms such as excess excretion of water, glucose, and phosphate in the urine. It has been shown that a mutation in HNF4A is associated with FRTS in humans and that Hnf4a is expressed specifically in proximal tubules in adult rat nephrons. However, little is known about the role of Hnf4a in nephrogenesis. Here, we found that Hnf4a is expressed in both presumptive and differentiated proximal tubules in the developing mouse kidney. We show that Hnf4a is required for the formation of differentiated proximal tubules but is dispensable for the formation of presumptive proximal tubules. Furthermore, we show that loss of Hnf4a decreased the expression of proximal tubule-specific genes. Adult Hnf4a mutant mice presented with FRTS-like symptoms, including polyuria, polydipsia, glycosuria, and phosphaturia. Analysis of the adult Hnf4a mutant kidney also showed proximal tubule dysgenesis and nephrocalcinosis. Our results demonstrate the critical role of Hnf4a in proximal tubule development and provide mechanistic insight into the etiology of FRTS.

Expression of Nek1 during kidney development and cyst formation in multiple nephron segments in the Nek1-deficient kat2J mouse model of polycystic kidney disease

BACKGROUND

Neks, mammalian orthologs of the fungal protein kinase never-in-mitosis A, have been implicated in the pathogenesis of polycystic kidney disease. Among them, Nek1 is the primary protein inactivated in kat2J mouse models of PKD.

RESULT

We report the expression pattern of Nek1 and characterize the renal cysts that develop in kat2J mice. Nek1 is detectable in all murine tissues but its expression in wild type and kat2J heterozygous kidneys decrease as the kidneys mature, especially in tubular epithelial cells. In the embryonic kidney, Nek1 expression is most prominent in cells that will become podocytes and proximal tubules. Kidney development in kat2J homozygous mice is aberrant early, before the appearance of gross cysts: developing cortical zones are thin, populated by immature glomeruli, and characterized by excessive apoptosis of several cell types. Cysts in kat2J homozygous mice form postnatally in Bowman's space as well as different tubular subtypes. Late in life, kat2J heterozygous mice form renal cysts and the cells lining these cysts lack staining for Nek1. The primary cilia of cells lining cysts in kat2J homozygous mice are morphologically diverse: in some cells they are unusually long and in others there are multiple cilia of varying lengths.

CONCLUSION

Our studies indicate that Nek1 deficiency leads to disordered kidney maturation, and cysts throughout the nephron.

A human in vitro model that mimics the renal proximal tubule

Human in vitro-manufactured tissue and organ models can serve as powerful enabling tools for the exploration of fundamental questions regarding cell, matrix, and developmental biology in addition to the study of drug delivery dynamics and kinetics. To date, the development of a human model of the renal proximal tubule (PT) has been hindered by the lack of an appropriate cell source and scaffolds that allow epithelial monolayer formation and maintenance. Using extracellular matrices or matrix proteins, an in vivo-mimicking environment can be created that allows epithelial cells to exhibit their typical phenotype and functionality. Here, we describe an in vitro-engineered PT model. We isolated highly proliferative cells from cadaveric human kidneys (human kidney-derived cells [hKDCs]), which express markers that are associated with renal progenitor cells. Seeded on small intestinal submucosa (SIS), hKDCs formed a confluent monolayer and displayed the typical phenotype of PT epithelial cells. PT markers, including N-cadherin, were detected throughout the hKDC culture on the SIS, whereas markers of later tubule segments were weak (E-cadherin) or not (aquaporin-2) expressed. Basement membrane and microvilli formation demonstrated a strong polarization. We conclude that the combination of hKDCs and SIS is a suitable cell-scaffold composite to mimic the human PT in vitro.

A test of the hypothesis that oxalate secretion produces proximal tubule crystallization in primary hyperoxaluria type I

The sequence of events by which primary hyperoxaluria type 1 (PH1) causes renal failure is unclear. We hypothesize that proximal tubule (PT) is vulnerable because oxalate secretion raises calcium oxalate (CaOx) supersaturation (SS) there, leading to crystal formation and cellular injury. We studied cortical and papillary biopsies from two PH1 patients with preserved renal function, and seven native kidneys removed from four patients at the time of transplant, after short-term (2) or longer term (2) dialysis. In these patients, and another five PH1 patients without renal failure, we calculated oxalate secretion, and estimated PT CaOx SS. Plasma oxalate was elevated in all PH1 patients and inverse to creatinine clearance. Renal secretion of oxalate was present in all PH1 but rare in controls. PT CaOx SS was >1 in all nonpyridoxine-responsive PH1 before transplant and most marked in patients who developed end stage renal disease (ESRD). PT from PH1 with preserved renal function had birefringent crystals, confirming the presence of CaOx SS, but had no evidence of cortical inflammation or scarring by histopathology or hyaluronan staining. PH1 with short ESRD showed CaOx deposition and hyaluronan staining particularly at the corticomedullary junction in distal PT while cortical collecting ducts were spared. Longer ESRD showed widespread cortical CaOx, and in both groups papillary tissue had marked intratubular CaOx deposits and fibrosis. CaOx SS in PT causes CaOx crystal formation, and CaOx deposition in distal PT appears to be associated with ESRD. Minimizing PT CaOx SS may be important for preserving renal function in PH1.

Renal functional decline and glomerulotubular injury are arrested but not restored by release of unilateral ureteral obstruction (UUO)

Murine unilateral ureteral obstruction (UUO), a major model of progressive kidney disease, causes loss of proximal tubular mass and formation of atubular glomeruli. Adult C57BL/6 mice underwent a sham operation or reversible UUO under anesthesia. In group 1, kidneys were harvested after 7 days. In group 2, the obstruction was released after 7 days, and a physiological study of both kidneys was performed 30 days later. Renal blood flow (RBF), glomerular filtration rate (GFR), urine protein, and albumin excretion were measured after ligation of either the left or right ureter. Glomerular volume (periodic acid-Schiff), glomerulotubular integrity and proximal tubular mass (Lotus tetragonolobus lectin), and interstitial collagen (Sirius red) were measured by histomorphometry. Obstructed kidney weight was reduced by 15% at 7 days but was not different from sham after a 30-day recovery. Glomerular volume and proximal tubular area of the obstructed kidney were reduced by 55% at 7 days, but normalized after 30 days. Interstitial collagen deposition increased 2.4-fold after 7 days of UUO and normalized after release. However, GFR and RBF were reduced by 40% and urine albumin/protein ratio was increased 2.8-fold 30 days after release of UUO. This was associated with a 50% reduction in glomerulotubular integrity despite a 30-day recovery (P < 0.05 for all data). We conclude that release of 7-day UUO can arrest progression but does not restore normal function of the postobstructed kidney. Although the remaining intact nephrons have hypertrophied, glomerular injury is revealed by albuminuria. These results suggest that glomerulotubular injury should become the primary target of slowing progressive kidney disease.

Fight-or-flight: murine unilateral ureteral obstruction causes extensive proximal tubular degeneration, collecting duct dilatation, and minimal fibrosis

Unilateral ureteral obstruction (UUO) is the most widely used animal model of progressive renal disease. Although renal interstitial fibrosis is commonly used as an end point, recent studies reveal that obstructive injury to the glomerulotubular junction leads to the formation of atubular glomeruli. To quantitate the effects of UUO on the remainder of the nephron, renal tubular and interstitial responses were characterized in mice 7 and 14 days after UUO or sham operation under anesthesia. Fractional proximal tubular mass, cell proliferation, and cell death were measured by morphometry. Superoxide formation was identified by nitro blue tetrazolium, and oxidant injury was localized by 4-hydroxynonenol and 8-hydroxydeoxyguanosine. Fractional areas of renal vasculature, interstitial collagen, α-smooth muscle actin, and fibronectin were also measured. After 14 days of UUO, the obstructed kidney loses 19% of parenchymal mass, with a 65% reduction in proximal tubular mass. Superoxide formation is localized to proximal tubules, which undergo oxidant injury, apoptosis, necrosis, and autophagy, with widespread mitochondrial loss, resulting in tubular collapse. In contrast, mitosis and apoptosis increase in dilated collecting ducts, which remain patent through epithelial cell remodeling. Relative vascular volume fraction does not change, and interstitial matrix components do not exceed 15% of total volume fraction of the obstructed kidney. These unique proximal and distal nephron cellular responses reflect differential "fight-or-flight" responses to obstructive injury and provide earlier indexes of renal injury than do interstitial compartment responses. Therapies to prevent or retard progression of renal disease should include targeting proximal tubule injury as well as interstitial fibrosis.

Nephron segment identification in the normal canine kidney by using lectin histochemistry

Lectin-binding patterns in normal canine kidneys were histochemically investigated using eight lectins. WGA, ConA, and RCA-I showed positive signals in glomerular capillary walls, with signals for RCA-I being detected heterogeneously. In tubular segments, signals for WGA, s-WGA, ConA, and RCA-I were distributed widely from proximal tubules to collecting ducts, whereas those for SBA, PNA, DBA, and UEA-I were localized in thin limbs of the loop of Henle, thick ascending limbs, distal tubules, or collecting ducts. Apart from PNA and UEA-I, lectins showed heterogeneous bindings in collecting ducts with the heterogeneity. UEA-I-positive reactions were restricted to those parts of the distal tubules in close proximity to the glomeruli, and in these parts, signals in the macula densa were markedly stronger than in other regions. Based on the present findings, lectin probes, singly or in combination, could be utilized to identify the affected nephron segment in canine renal pathology.

Proximal tubular injury and rapid formation of atubular glomeruli in mice with unilateral ureteral obstruction: a new look at an old model

Unilateral ureteral obstruction (UUO), employed extensively as a model of progressive renal interstitial fibrosis, results in rapid parenchymal deterioration. Atubular glomeruli are formed in many renal disorders, but their identification has been limited by labor-intensive available techniques. The formation of atubular glomeruli was therefore investigated in adult male mice subjected to complete UUO under general anesthesia. In this species, the urinary pole of Bowman's capsule is normally lined by tall parietal epithelial cells similar to those of the proximal tubule, and both avidly bind Lotus tetragonolobus lectin. Following UUO, these cells became flattened, lost their affinity for Lotus lectin, and no longer generated superoxide (revealed by nitroblue tetrazolium infusion). Based on Lotus lectin staining, stereological measurements, and serial section analysis, over 80% of glomeruli underwent marked transformation after 14 days of UUO. The glomerulotubular junction became stenotic and atrophic due to cell death by apoptosis and autophagy, with concomitant remodeling of Bowman's capsule to form atubular glomeruli. In this degenerative process, transformed epithelial cells sealing the urinary pole expressed α-smooth muscle actin, vimentin, and nestin. Although atubular glomeruli remained perfused, renin immunostaining was markedly increased along afferent arterioles, and associated maculae densae disappeared. Numerous progressive kidney disorders, including diabetic nephropathy, are characterized by the formation of atubular glomeruli. The rapidity with which glomerulotubular junctions degenerate, coupled with Lotus lectin as a marker of glomerular integrity, points to new investigative uses for the model of murine UUO focusing on mechanisms of epithelial cell injury and remodeling in addition to fibrogenesis.

Histogenesis of the acquired cystic kidney disease: an immunohistochemical study

The aim of this study was to characterize by immunohistochemistry the histogenesis of cysts in acquired cystic kidney disease (ACKD). Thirty renal tissues fixed in 10% formalin and embedded in paraffin from 20 cases of ACKD were studied. Vimentin was used to stain the Bowman's capsule epithelium, Lotus tetragonolobus agglutinin (LTA) and Leu M1 (CD15) for proximal tubules; Tamm-Horsfall protein (THP) for distal tubules; epithelial membrane antigen (EMA), cytokeratin 19 (CK19), Arachis hypogea agglutinin (PNA), and Glycine maximum agglutinin (SBA) for distal tubules and collecting ducts; and Ulex europaeus agglutinin (UEA-I) and Dolichos biflorus agglutinin (DBA) for collecting ducts. A histologically normal kidney, free of cystic disease, was used as a control for all the markers. Most of the cysts showed strong reactivity to LTA and CD15, an immunophenotype more characteristic of proximal tubules.

Lectin histochemistry shows fucosylated glycoconjugates in the primordial germ cells of Xenopus embryos

Previous works have shown that glycoconjugates with terminal fucose (Fuc) are located in the primordial germ cells (PGCs) of some mammals and might play a role in the migration and adhesion processes during development. The aim of this work was to identify the terminal Fuc moieties of Xenopus PGCs by means of three Fuc-binding lectins: from asparagus pea (LTA), gorse seed (UEA-I), and orange peel fungus (AAA). The histochemical procedures were also carried out after deglycosylation pretreatments: beta-elimination with NaOH to remove O-linked oligosaccharides; incubation with PNGase F to remove N-linked carbohydrate chains; and incubation with alpha(1,2)- and alpha(1,6)-fucosidase. The PGCs were always negative for LTA and UEA-I, two lectins that have the highest affinity for Fuc alpha(1,2)-linked. However, the PGCs were strongly labeled with AAA, which preferentially binds to Fuc with alpha(1,3) or alpha(1,4) linkages and to Fuc alpha(1,6)-linked to the proximal N-acetylglucosamine. There was fainter labeling with AAA when the sections were preincubated with alpha(1,6)-fucosidase, but the labeling remained strong when the sections were pretreated with alpha(1,2)fucosidase. When the beta-elimination procedure was carried out, the PGC labeling with AAA was slight. If the PNGase F incubation was performed, the PGCs remained moderately positive for AAA. These data suggest that the Xenopus PGCs have Fuc moieties in O- and N-linked oligosaccharides, including Fuc alpha(1,6) linked to the innermost GlcNAc, and that the Fuc was not in alpha(1,2)-linkage.

Renal tubular dysgenesis (RTD) - an important cause of the oligohydramnion-sequence. Report of 3 cases and review of the literature

Renal tubular dysgenesis (RTD) is a disorder characterized by neonatal renal failure and regular gross renal architecture, although the histological features of immature and shortened proximal tubules lead to neonatal death. The pathogenesis of this condition includes a congenital familial condition, a twin-twin transfusion syndrome, and an angiotensin-converting enzyme inhibitor intake by the mother. The clinical picture shows an association with oligohydramnia, pulmonary hypoplasia, and skull ossification defects. In the present paper, we report the occurrence of RTD in three infants of a consanguinous couple and compared our data with those of the literature. Our data confirm that late second trimester demonstration of oligohydramnion, with structurally normal kidneys and with or without skull ossification defects, allows the diagnosis of renal tubular dysgenesis, which, however, has to be confirmed by histological and immunohistological examinations of the kidney.

Identification of nucleated cells in urine using lectin staining

Microscopic examination of urinary sediment is an integral component in the evaluation of nephropathies. However, identification and differentiation of the nucleated nonsquamous cells in urine is often difficult using such conventional techniques as phase contrast or bright field microscopy, even after Papanicolaou staining, and requires a lot of experience. We now report a method to differentiate urinary cell types using lectin staining. Twenty-five lectins were examined with respect to their binding pattern on cryosections of the human kidney and urinary tract, as well as binding to blood cells. The specificity of lectin binding to a cell type both in situ and in urine was confirmed by double labeling with specific antibodies directed against various sections of the nephron or nucleated blood cells. For urine cytologic examinations, acetone-fixed cytopreparations of urinary sediments were incubated with a combination of a fluorescein isothiocyanate (FITC)-coupled and a rhodamine-coupled lectin, followed by staining of the nuclei with 4',6-diamidino-2-phenylindole. Specimens were examined in triple immunofluorescence (FITC/rhodamine/UV). Cell types could be identified by their characteristic lectin-binding pattern. For example, the lectin combination of Sophora japonica agglutinin (aggl; SJA) and Erythrina cristagalli aggl (ECA) permitted a differentiation between cells of the proximal tubules (SJA positive [SJA+], ECA+), distal tubules (SJA negative [SJA-], ECA+), collecting ducts (SJA+, ECA-), and lymphocytes (SJA-, ECA-). In preliminary studies, examination of urinary sediment in various chronic nephropathies by this technique showed differences in their cellular excretion pattern. In summary, staining urinary sediments with combinations of lectins provides a rapid and relatively inexpensive method for a facilitated and reliable differentiation of the various nucleated cell types in urine.

Renal tubular dysgenesis in twin-twin transfusion syndrome

In twin-twin transfusion syndrome (TTTS), the disparity in circulation is reflected in discordant fetal growth, urine output, and amniotic fluid accumulation. The effect of uneven shunting of the growth factor and nutrient-rich vasculature on development and differentiation of the kidney has not been well studied. We analyzed renal tubular growth and differentiation in 25 fetal autopsies with TTTS (13 donors and 12 recipients, including 9 sibling pairs) between 18 and 33 weeks gestation. Immunohistochemical markers for fumarylacetoacetate hydrolase (FAH), Leu-M1, and Lotus tetragonolobus (LTA) were used to identify proximal convoluted tubules, and epithelial membrane antigen (EMA) was used to demonstrate distal convoluted and collecting tubules. FAH appeared to be more specific and reliable than either Leu-M1 or LTA in the identification of proximal tubules. Donors tended to demonstrate a paucity of proximal tubules with crowding of glomeruli characteristic of renal tubular dysgenesis (RTD). The degree of dysgenesis was greater in later gestations and associated with more severe growth restriction. Donors in TTTS are at risk for the development of RTD. Several authors suggest ischemia as the underlying cause of "acquired" RTD. However, in this setting there is no evidence of cell death or necrosis, and we suggest that hypoperfusion leading to decreased glomerular filtration is the underlying etiology, with the severity of RTD related to the degree of shunting.

Nephron segment and cell-type specific expression of gangliosides in the developing and adult kidney

Despite the increasing knowledge of the role of gangliosides in normal and diseased tissues, little is known of the presence, distribution and functions of these molecules in the kidney. In this study we analyzed the main gangliosides of isolated glomeruli and cortical, medullary and papillary fractions of the human, rat and bovine kidneys biochemically. In addition, we used immunohistochemistry to visualize the distribution of GM1/GM2, GD2, GD3 and O-acetyl GD3 gangliosides along the nephron. Furthermore, we explored the species specific expression of gangliosides by comparing those from the rat, bovine and human kidney, and studied the pattern of ganglioside expression during development. In glomeruli, cortical tubuli, medullae and papillae, a relatively simple pattern of main gangliosides was observed as revealed by thin layer chromatographic (TLC) analysis in each species studied. Furthermore, considerable changes in the glomerular gangliosides during maturation were observed, with a complex type of gangliosides predominating during the fetal age and with a preference to more simple precursors upon maturation. Interestingly, the immunohistochemical detection revealed a distinct pattern of ganglioside compartmentation to various nephron segments or cell types. These findings provide a basis for studying the role of segment- and cell type-specific gangliosides for local functions.

Study of renal tubular glycoconjugates in tubulointerstitial damage using conjugated lectins

Changes in the glycoconjugates of renal tubules associated with tubular damage were studied by lectin histochemistry, and their possible significance was determined. The excretion of various saccharides in tubular casts may also serve as markers of renal tubular damage. Renal tissues from 55 cases with various glomerular diseases including ten controls were studied. The patients were divided into two groups: one with tubulointerstitial lesions (TILs) (30 cases), and the other without (15 cases). Our results showed a wide spectrum of changes, predominantly in the disease group with TILs. The brush border of the proximal tubules showed significantly increased staining with Triticum vulgaris (WGA) and decreased staining with Canavalia ensiformis (Con A) lectins in both disease groups. The distal tubules revealed a significant increase in the apical and a decrease in the basal staining with Arachis hypogaea (PNA) and WGA lectins, respectively, in cases with TILs. The significant decrease in the basal domain staining was also seen with WGA lectin in cortical ducts. The vulnerability of various segments of the tubules in the process of TILs was clearly demonstrable. It appeared that the distal tubules were the most vulnerable anatomical segments around which the TILs began and later spread to involve other segments of tubules.

Developmental pattern of Thy-1 immunoreactivity in the human kidney and the application to pediatric renal neoplasms

The localization of Thy-1, a surface membrane lipoglycoprotein, was investigated using a monoclonal antibody specific for human Thy-1 (HB-2S-1). The localization of Thy-1 during development was established in a series of five fetal, three childhood, and two adult normal kidneys. In this series, Thy-1 immunolocalization progressed from mesangial and endothelial cell staining in the 16- to 17-week fetuses to similar staining along with staining of the parietal epithelium of the capsule and proximal tubule staining in the 20- to 24-week fetuses. Glomerular mesangial cell and endothelial cell staining was absent by 9 months postnatally when the adult pattern of staining was apparent. The localization of Thy-1 during development was also compared with a series of pediatric renal tumors including 14 Wilms' tumors, 3 congenital mesoblastic nephromas, 1 clear cell sarcoma, and 1 pediatric renal cell carcinoma. Thy-1 staining was demonstrated in epithelial tubules of Wilms' tumors and in the spindle-shaped cells of congenital mesoblastic nephroma correlating with Thy-1 immunoreactivity in the kidney proximal tubule and fetal medullary stroma, respectively. Thy-1 staining was absent in the anaplastic epithelial Wilms' tumor, the renal cell carcinoma, and the clear cell sarcoma. This staining pattern fails to provide evidence that these tumors may arise from the medullary mesenchyme or the differentiated proximal convoluted tubule. These results show that Thy-1 is a renal differentiation marker and is useful in the characterization of tumors of renal development.

Heterogenous distribution of glycoconjugates in the kidney of dogfish Scyliorhinus caniculus (L.) with reference to changes in the glycosylation pattern during ontogenetic development of the nephron

Eight fluorochrome-coupled lectins with different sugar specificities were applied to cryosections of dogfish kidney. Despite profound differences in renal architecture between elasmobranch fish and other vertebrates, the sequence of nephron segments as revealed by the lectin-binding pattern was rather similar to that of tetrapodes. Wheat germ agglutinin (WGA) bound to cell membranes of epithelial cells of glomeruli, proximal and distal tubules, their basement membranes, the collecting tubule, and epithelial cells. Among other broadly binding lectins were Ricinus communis agglutinin I (RCA-I), soybean agglutinin (SBA), peanut agglutinin (PNA), Lycopersicon esculentum agglutinin (LEA), and Jacalin, all of which marked proximal as well as distal portions of the renal tubule. Dolichos biflorus agglutinin (DBA) did not react with any renal structure. Ulex europaeus agglutinin I (UEA-I), which indicates the presence of alpha-L-fucose, very strongly and specifically marked single epithelial cells of the early distal nephron, all epithelial cells of the late distal tubule, the beginning of the collecting tubule in the mesial tissue zone, and single cells in the end portion of the collecting tubule in the lateral bundles. Binding of UEA-I to receptors of distal nephron cells could be useful for the identification of these cells in functional studies employing teased tubule and/or isolated cell preparations. Binding of UEA-I to dogfish kidney structures resembles staining with UEA-I conjugates of late distal tubules and collecting tubules in the kidneys of frog and other, higher vertebrates. Epithelial cells of early developmental stages showed, very rarely, binding sites for most lectin-fluorochrome conjugates. A large number of lectin binding sites was observed in the extracellular matrix of fibroblast layers surrounding the early anlage and the S-shaped body. Lectin binding sites of the nephron epithelia appeared in a sequential manner in the next stages of development of the nephron. Ontogenetic and phylogenetic aspects of the merging region between nephron proper (late distal tubule) and collecting system (collecting tubule) are discussed.

Sialylated glycoconjugates in chromophobe cell renal carcinoma compared with other renal cell tumors. Indication of its development from the collecting duct epithelium

The present study was designed to shed light on the extraordinary histochemical properties of the chromophobe cell renal carcinoma detected by Hale's colloidal iron reaction. Special emphasis was laid on the lectin histochemical analysis of cytoplasmic glycoconjugates. Binding of peanut agglutinin (PNA) and Erythrina cristagalli agglutinin (ECA) after enzymatic release of sialic acid and direct binding of Dolichos biflorus agglutinin (DBA) correlates well with the expression of binding sites for Sambucus nigra agglutinin (SNA) and Maackia amurensis agglutinin (MAA) revealing abundant sialylated carbohydrate moieties within the cytoplasm. This characteristic binding pattern differs considerably from the faint staining observed in the majority of other renal carcinomas, thus confirming that the chromophobe cell renal carcinoma is a distinct entity. However, the lectin binding pattern of renal oncocytoma obviously resembles that of chromophobe carcinoma indicating a close relationship between these renal tumors. Detailed analysis of adjacent renal parenchyma revealed a lectin binding pattern quite similar to that described in the chromophobe carcinomas exclusively in the intercalated cells lining the collecting duct. This finding suggests that the chromophobe cell renal carcinoma originates from the collecting duct epithelium. The detection of small complexes consisting of altered epithelia which display the morphological characteristics of chromophobe carcinoma and the histochemical properties of intercalated cells probably indicates the emergence of preneoplastic lesions preceding the development of chromophobe carcinoma. Even though further studies are clearly needed to elucidate the physiological role of the cellular glycoconjugates detected, the present results already provide valuable insight into the histogenesis and pathogenesis of the chromophobe cell renal carcinoma.

Sexual dimorphism of the kidney in the NMRI mouse as shown by Dolichos biflorus agglutinin labelling

The histological affinity pattern of Dolichos biflorus agglutinin (DBA) in kidneys from mice (NMRI, Balb/c, CBA) and rats (Wistar) fixed by perfusion with formalin, Bouin, or HgCl2 was investigated with a horseradish peroxidase conjugate. The animals were examined from fetal stage to adulthood. Adult female NMRI mice exhibited constant DBA labelling, with DBA binding to cells of the proximal and collecting tubules. Moreover the vascular endothelium of the renal papilla was found to be DBA-positive in 50% of adult female animals. In contrast, there was only very little DBA binding in the kidneys of male adult NMRI mice. There was no sexual dimorphism in lectin labelling in kidneys from other strains of mice or from rats.

Histochemical and cytochemical localization of blood group antigens

The oligosaccharide structures of blood group antigens are not the primary gene products; they are constructed in a stepwise manner by adding particular sugar to precursor oligosaccharides via several glycosyltransferases coded for by different blood group genes (Watkins 1966, 1978, 1980). Consequently, final profiles of antigens expressed in each cell type are influenced by many different factors such as the intrinsic composition of glycosyltransferase species which are defined by the genotype of the individuals, relative activity or amount of these enzymes (repression, derepression or induction of the enzymes), competition between enzymes with overlapping substrate specificity, the organization of the enzymes in membranes, utilizability of precursors and specific substrate sugars, and the activity level of degradating enzymes. Changes in the antigen profiles during maturation, differentiation and malignant transformation are thought to be intimately related to the variability of these factors. Although great importance attaches to histo- and cytochemical information on the distribution and levels of glycosyltransferases and messenger RNA corresponding to the relevant enzyme, detailed and precise localization of the blood group antigens and their variants is the base line for analyzing these complex factors. On the basis of individual genotype and histochemical findings about the antigen distribution and the interrelationship between cells and cellular components producing different antigenic structures (cellular and subcellular mosaicism), we can deduce precursor oligosaccharide levels as well as the status of gene activation and its primary product, glycosyltransferases. Thus, these findings are a prerequisite for further analysis at the molecular genetic level. As emphasized in this article, lectin staining or immunostaining methods with MAbs combined with glycosidase digestion procedures are powerful tools for in situ analysis of carbohydrate structures in histochemical systems. Although in some cases valuable results have been obtained by applying the technique, our knowledge concerning the distribution of complex carbohydrate structures is still far from satisfactory. Along with well defined MAbs and lectins, the key to developing our methods further is successful introduction of glycosidases, in particular, endoglycosidases since these reagents are indispensable for analyzing the inner core structures and glycoconjugate species of the blood group antigens. Application of these techniques at the ultrastructural level is an alluring possibility, even though many difficulties must be overcome. Although their functional roles have not yet been determined, a diverse array of macromolecules is known to be decorated with blood group-related antigens.(ABSTRACT TRUNCATED AT 400 WORDS)

Confocal microscopic and other observations on the distal end of the thick limb of the human loop of Henle

Various antibodies and lectins were used in a histological study of the human renal tubule, particularly of the distal end of the thick limb of the loop of Henle. The thick limb, identified by antibody to Tamm-Horsfall protein, ended abruptly, either at the macula densa or at a variable distance after it. At this point there was an abrupt change in cell size. Confocal microscopy and other techniques showed that this point marked an abrupt beginning of tubular staining by the cytokeratin antibody PKK2 and the lectin UEA 1, with an abrupt end of staining by the lectin DBA. Distal from this point, there were gradual changes in staining of the tubule by various reagents including other antibodies to cytokeratins. These structural findings suggest that there is a fundamental change in the tubule at the end of the thick limb. The abrupt end to the thick limb in man resembles that seen in the rat and the rabbit.

Immunohistochemical identification of tubular segments in percutaneous renal biopsies

To identify the renal cortical tubular segments involved in tubulo-interstitial disease in formalin-fixed, paraffin-embedded percutaneous kidney biopsies, we developed multiple immunolabeling protocols using segment-specific tubular markers. The present study of biopsies from patients with minimal change or thin basement membrane nephropathy provides a baseline for interpretation of histopathology. Proximal tubules were stained either by the PAS reaction or by the biotinylated Phaseolus vulgaris erythroagglutinin (PHA-E)-streptavidin-gold-silver system (brush borders black). The anti-Tamm-Horsfall (THP) antibody-immunoperoxidase (aminoethylcarbazole, AEC-IPO), and anti-epidermal cytokeratins (ECK) antibodies-immunoalkaline-Fast Blue BB methods marked the distal straight tubules and the cortical collecting system red-brown and blue, respectively. When these immunolabelings were combined, the coapplication of AEC-PO-labeled peanut agglutinin (PNA) or anti-epithelial membrane antigen antibody-AEC-IPO technique (both are markers for distal nephron) visualized the apical membranes of distal convoluted tubules. In the protocol PHA-E + PNA + THP + ECK, the tubular basement membranes were outlined by the anti-laminin antibody-AEC-IPO staining, carried out simultaneously. The protocol PNA + THP + ECK + PAS was found to be quite appropriate multiple immunolabeling method for the tubules, and is recommended for use as a tool in the study of tubulo-interstitial diseases.

Comparison of Dolichos biflorus lectin and other lectin-horseradish peroxidase conjugates in staining of cutaneous blood vessels in the hairless mini-pig

Angiogenesis is necessary for normal growth, wound healing, and plays a key role in many pathologic processes. A variety of endothelial markers have been used to investigate angiogenesis. Unfortunately, excellent markers for vascular endothelium in human tissues exhibit little or no staining of endothelia in tissues of other animal species, including the pig. We are interested in the hairless Yucatan strain of mini-pig as an animal model for studying cutaneous wound healing because its skin is histologically and functionally very similar to that of man. Hoping to find a specific marker to identify vascular endothelium in the mini-pig, we therefore screened a battery of 11 different lectin-horseradish peroxidase conjugates. Based on specificity and staining intensity, Dolichos biflorus agglutinin (DBA) was chosen from this battery to investigate vascular changes in the healing of cutaneous wounds in the mini-pig. When compared with routine histologic sections stained with hematoxylin and eosin, blood vessels were much easier to identify in sections stained histochemically with DBA. Lectin histochemistry was particularly useful in investigations of early events in angiogenesis during wound healing when newly derived capillary buds and minute blood vessels were obscured in normal histologic sections by an inflammatory cell infiltrate associated with the healing wound. Ultrastructural lectin cytochemistry revealed staining along the luminal surface and the basolateral plasmalemma of endothelial cells. Histochemical staining with DBA promises to provide a useful method for further investigation of angiogenesis and other vascular phenomena in a variety of normal and pathologic processes using the hairless Yucatan strain of mini-pig as the animal model.

Binding of the blood group-reactive lectins to human adult kidney specimens

The binding of a panel of blood group-reactive lectins to frozen sections of human kidney was studied with a special emphasis on reactivity with endothelia and basement membranes. The blood group A-reactive lectins, all specific for alpha-D-N-acetylgalactosamine (GalNAc), Helix aspersa (HAA), Helix pomatia (HPA), and Griffonia simplicifolia I-A4 (GSA-I-A4) agglutinins bound to the endothelium in specimens with blood groups A and AB. In other samples, these lectins reacted predominantly with tubular basement membranes, as well as with certain tubules. Both Dolichos biflorus (DBA) and Vicia villosa agglutinins (VVA), reported to react with blood group A1 substance, failed to reveal endothelia in most specimens, but bound differently to tubules in all blood groups. The blood group B-reactive lectins, specific for alpha-D-galactose (alpha-Gal) or GalNAc, respectively, GSA-I-B4 and Sophora japonica agglutinin (SJA), bound to the endothelia in specimens from blood group B or AB and in other specimens bound only to certain tubules. Among the blood group O-reactive lectins, specific for alpha-L-fucose (Fuc), Ulex europaeus I agglutinin (UEA-I) conjugates, but not other lectins with a similar nominal specificity, bound strongly to endothelia in specimens with blood group O. The UEA-I conjugates bound distinctly more faintly to endothelia in specimens of other blood groups. The present results indicate that lectins, binding to defined blood group determinants, react with endothelia in specimens of the respective blood group status. Furthermore, they suggest that basement membranes and some tubules in the human kidney show a distinct heterogeneity in their expression of saccharide residues, related to their blood group status.

Histochemical detection of sugar residues in the chick embryo mesonephros with lectin-horseradish peroxidase conjugates

Fragments of mesonephros were taken from chick embryos and studied from the 4th to the 21st day of incubation. A battery of seven different horseradish peroxidase-labelled lectins was used to study the distribution of carbohydrate residues in glycoconjugates along the mesonephric nephron during the period of excretory activity and the period of involution. ConA and WGA reacted at every site of the nephron thus showing the ubiquitous presence of alpha-D-mannose and N-acetyl-D-glucosamine. SBA was a good marker of the proximal tubule. Other lectins, such as PNA and LTA, reacted only for a short time at some sites during the considered period of incubation. The presence of sialic acid was detected in the podocytes, capillary wall and mesangial cells. From the 10th-11th day of incubation changes were noted in the proximal tubule as shown by PNA reactivity. This may be significant as regards the exact stage of incubation during which the involution of mesonephros begins.

Acute tubulointerstitial nephritis in children: clinical, morphologic, and lectin studies. A report of the Southwest Pediatric Nephrology Study Group

Clinical histories and renal biopsies were reviewed in 12 children with acute tubulointerstitial nephritis, which was drug related in eight, idiopathic in one, and multifactorial in three. Presentation with rashes and hypertension was most common in patients with drug-associated nephritis. Eosinophils, which were present in the majority of the renal biopsies, did not distinguish between drug-related and non-drug-related disease. The majority of the children had a good outcome irrespective of the insulting agent. Frequent tubular basement membrane breaks were identified in seven of the biopsies but were not associated with a poor outcome. Proximal tubule brush border thinning, demonstrated by periodic acid-Schiff and Tetragonolobus lotus staining, paralleled the severity of acute renal failure. Lectin and immunohistochemical techniques to identify proximal tubules (Tetragonolobus lotus), thick ascending limb of Henle (anti-Tamm-Horsfall protein antibodies), and collecting ducts (Arachis hypogaea) allowed better delineation of sites of inflammation and injury, showed collecting tubules to be involved in all cases, and demonstrated that small atrophic tubules were able to maintain the ability to stain with the appropriate lectin/antibody. It is proposed that studies using these techniques may better identify the nephron sites involved in a variety of renal diseases involving tubular segments.

The use of lectins in histopathology

Lectins are proteins and glycoproteins extracted predominantly from plants which have the capacity to bind sugars specifically. This property makes them of interest for histopathology since they will bind to saccharides forming parts of glycoproteins and glycolipids of tissue constituents. Lectins have and can be used as reagents for mucin histochemistry, to identify specific cells, in the recognition of glycoprotein alterations in disease states, in studies of infectious diseases, and in the assessment of glycoconjugate alterations occurring with malignancy. They can be used for both light microscopic and ultrastructural localisation and various methods are available. It is important though, to consider the nature of the glycoconjugates under study and select lectins appropriately because of their varying specificities and binding characteristics. A panel of lectins should be used to study a particular configuration. Care should be taken with tissue fixation and processing. It must be remembered that an open and critical mind should be kept concerning interpretation of results. At the present time lectins have a limited value diagnostically, but the binding of Ulex europeus agglutinin to endothelium is certainly of value.

Purified P fimbriae from two cloned gene clusters of a single pyelonephritogenic strain adhere to unique structures in the human kidney

We have completed immunofluorescence binding studies of purified fimbriae from two clones which express Pap or Pap-2 fimbriae. Although the two fimbrial types exhibited common binding to the uroepithelia of the bladder and renal pelvis and to occasional cells located within the glomeruli which we have termed glomerular elements, only Pap-2 fimbriae adhered to Bowman's capsule. Previous studies have demonstrated that the Gal alpha 1----4Gal disaccharide moiety is capable of inhibiting Pap hemagglutination and adherence to uroepithelial cells. Results of our experiments demonstrate that this disaccharide is not sufficient for blocking binding of Pap-2 fimbriae to Bowman's capsule but that GalNAc beta 1----3Gal completely blocks Pap-2 adherence to Bowman's capsule. These results indicate that the different hemagglutination capacities of the two clones reflect different receptor specificities and differential tissue tropisms in the urinary tract. These unique receptor specificities may provide uropathogenic strains of Escherichia coli carrying multiple chromosomal copies of pap-like gene clusters with the advantage of increased numbers of binding sites within the urinary tract. This, in turn, might improve the chances of colonization and the establishment of infection.

[Cellular specificity of lectin binding in the kidney of the quail (Coturnix coturnix japonica)]

The goal of this study was to demonstrate the distribution of glycoproteins in the various segments of the Japanese quail nephron, using lectins labeled with HRP or FITC. Each one of the six labeled lectins had a characteristic distribution pattern along the nephron. The study shows that lectins are useful markers for certain nephron segments or for cell types in certain segments of the renal tubules. PNA marks the thin portion of the medullary loop, DBA marks the thick portion; it is thus possible to differentiate the nephron segments in the medullary cone of the kidney. Con A binds selectively with the epithelioid, granular cells of the tunica media of the vasa efferentia. The histochemical technic using labeled lectins makes it possible to identify certain renal structures that could not, or only with difficulty, be differentiated using conventional histology. Therefore, lectins as specific markers are gaining in importance for further studies of the morphology and physiology of the kidney.

Presence of an alpha-galactolipid on the cell surfaces of endothelial cells of human kidney

The presence of an alpha-galactolipid was investigated with a peroxidase-labelled lectin from Griffonia simplicifolia (GSA-I) with specific binding for terminal alpha-D-galactose residues. Normal kidney tissue was obtained from patients undergoing nephrectomy for renal neoplasms. For light microscopy, tissue was snap-frozen; 4 microns-thick sections were briefly fixed in paraformaldehyde and incubated with GSA (0.025 mg ml-1). The peroxidase activity was developed with 3-amino-9-ethylcarbazole. Adjacent sections were stained at the same time after lipid extraction with 3:1 (v/v) chloroform/methanol. For electron microscopy, 0.2-0.5 mm-thick paraformaldehyde-fixed blocks, with or without lipid extraction, were stained with peroxidase-labelled GSA. The label was developed with diaminobenzidine and osmium tetroxide. Some structures, such as tubular epithelia, stained both in lipid-extracted and non-extracted tissues, suggesting that glycoproteins were most likely involved. In addition, tissue stained immediately after fixation showed GSA reactivity on endothelial cell surfaces of intertubular capillaries and larger vessels. In lipid-extracted tissues, however, tubular epithelium was still positive for GSA but endothelial cells failed to stain. These findings suggest that a glycolipid, bearing a terminal alpha-galactose residue, is present on the endothelial cells in human kidney and possibly on tubular epithelia. Our data may explain the preferential storage of alpha-galactolipid in endothelial cells of patients with Fabry's disease and other biological phenomena such as Escherichia coli adhesion.

Lectin-detectable effects of localized pneumonia on airway mucous cell populations: role of cyclooxygenase metabolites

We examined the airway secretory apparatus of adult sheep with experimental pneumonia to look for morphologic and lectin-binding correlates of increased mucus production. The animals were inoculated in the right caudal lobar bronchus either with starch broth containing Pasteurella haemolytica (INF, n = 6), starch broth alone (SHAM, n = 6), or with P. haemolytica and subsequently treated (INF/T, n = 5) with 2 mg/kg indomethacin, subcutaneously three times daily for 6 days. In the INF and INF/T groups, a localized pneumonic infiltrate containing P. haemolytica organisms was present. The bronchi (18-23rd generation) adjacent to the pneumonic lesion had an increased gland volume fraction (6.3 +/- 3.7% in INF, 11.3 +/- 2.4% in INF/T, and 3.1 +/- 1.9% in SHAM, p less than 0.05 among the three). The mean population densities of BSA-reactive (identifying alpha-D-gal) cells were 41.9 +/- 2.7% in the INF, 40.1 +/- 5.6% in the INF/T, versus 14.3 +/- 1.5% in the SHAM group (p less than 0.05), while the corresponding values for PNA-reactive [identifying beta-D-gal(1----3)-D-galNAc] cells were 28.8 +/- 5.1%, 0%, and 0%, respectively. Nor morphologic abnormalities were seen in the trachea, but BSA staining was shifted to morphologically different mucous cells in the INF and INF/T. We conclude that in localized P. haemolytica pneumonia in sheep (1) there are morphologic changes of the airway secretory apparatus adjacent to the lesion, (2) the glycoconjugate profile of secretory cells adjacent to and remote from the lesion is altered, and (3) cyclooxygenase products influence the chemical composition of secretory cells.

Renal cystic disease of infancy: results of histochemical studies. A report of the Southwest Pediatric Nephrology Study Group

Histochemical techniques utilizing Tetragonolobus lotus (proximal tubules), Arachis hypogaea (distal nephron, i.e., distal convoluted tubules and collecting ducts), and antibodies against Tamm-Horsfall protein (thick ascending limbs of Henle) were used to determine the site of origin of renal cysts in five children with autosomal recessive polycystic kidney disease (ARPKD) and three patients with glomerulocystic disease (GCD) presenting in the 1st year of life. The findings support a distal nephron origin for the cysts in the children who had ARPKD, whereas the majority of cysts in the children with GCD were confirmed as having a glomerular origin. Tamm-Horsfall protein was identified in the cysts of both ARPKD and GCD; this finding suggests free communication between some of the cysts with the thick ascending limb of Henle. An unexpected finding was the frequent presence of cysts surrounded by muscle fibers. We suggest that these cysts are of collecting duct origin.

Binding characteristics of Escherichia coli adhesins in human urinary bladder

We studied domains in the human bladder that acted as receptors for Escherichia coli P, S, type 1, type 1C, and O75X fimbriae or adhesin and domains in the human kidneys that were receptors for E. coli type 1C fimbriae. Binding sites in frozen tissue sections were localized by direct staining with fluorochrome-labeled recombinant strains and by indirect immunofluorescence with the purified adhesins. In the bladder, the P and S fimbriae showed closely similar binding to the epithelial and muscular layers, and the S fimbriae also bound to the connective tissue elements. Type 1 fimbriae bound to vascular walls and to muscle cells, whereas the O75X adhesin bound avidly to connective tissue elements and to some extent to epithelial and muscle cells of the bladder. The type 1C fimbriae bound to distal tubules and collecting ducts of the kidney and to vascular endothelial cells in both the kidney and bladder. The binding of all adhesin types was inhibited by specific receptor analogs or Fab fragments. The results reveal a possible mechanism by which the type 1C fimbriae may help invasion of E. coli in the kidneys but do not support a pathogenetic role for type 1 fimbriae. Similar tissue specificity of P and S fimbriae in the human urinary tract indicates that the presence of binding sites on uroepithelia does not fully explain the virulence properties of P fimbriae in human urinary tract infections.

Heterogeneity of apical glycoconjugates in kidney collecting ducts: further studies using simultaneous detection of lectin binding sites and immunocytochemical detection of key transport enzymes

In the search for a functional role for the polarized glycoconjugates of rat collecting duct epithelial cells, the relation between binding of various lectins and expression of cellular transport enzyme profile of the cells was studied. For this purpose, principal and intercalated cells of rat kidney collecting duct were identified by morphological criteria and by their immunocytochemically determined content of (Na+ + K+)-ATPase and carbonic anhydrase (CA II), respectively. Various N-acetylgalactosamine-specific lectins such as those from Helix pomatia and Maclura pomifera revealed heterogeneity among both principal and intercalated cells, whereas alpha-N-acetylgalactosamine-specific lectin from Dolichos biflorus and Vicia villosa bound preferentially to principal cells. Still another lectin from Arachis hypogaea reacted with most collecting duct cells in the cortex and outer medulla, but only with a subpopulation of cells in the inner medulla. Interestingly, some lectins reacted exclusively with the apical aspect of the collecting duct epithelial cells, whereas others revealed both an apical and basolateral distribution of lectin reactive glycoconjugates. The results thus show subtle differences in the glycocalyx structure of principal and intercalated cells and differences in the intracellular polarization of glycoconjugates of these cells. Thus, lectins may be useful tools in the study of the molecular mechanisms which establish and maintain the polarized functions of principal and intercalated cells.

Tracheobronchial epithelium of the sheep: IV. Lectin histochemical characterization of secretory epithelial cells

Conventional histochemical characterization of the mucus secretory apparatus is often difficult to reconcile with the biochemical analysis of respiratory secretions. This study was designed to examine the secretory glycoconjugates in airways using lectins with biochemically defined affinities for main sugar residues of mucus. We used five biotinylated lectins--DBA (Dolichos biflorus) and SBA (Glycine max) for N-acetyl galactosamine (galNAc), BSA I (Bandeiraea simplicifolia) and PNA (Arachis hypogea) for galactose (gal), and UEA I (Ulex europeus)--for detection of fucose (fuc) in HgCl2-fixed, paraffin-embedded, serially sectioned trachea, lobar and segmental bronchi and bronchioles of nine sheep. Lectins selectively localized the carbohydrate residues in luminal secretions, on epithelial cell surfaces, and in secretory cells. In proximal airways, the major carbohydrate residues in luminal secretions, cell surfaces, goblet cells, and glands were fuc and gal-NAc. PNA reacted mainly with apical granules of less than 10% of goblet cells, and gal residues were only detected in some of the mucous cells and on basolateral cell surfaces. Distal airways contained sparse secretion in the lumen, mucous cells contained weakly reactive fuc and gal-NAc, and the epithelial surfaces of Clara cells contained gal. Sugars abundant in the airway secretions were also the major component of cells in glands. We conclude that there is a correlation between specific sugar residues in secretory cells, glycocalyx, and luminal secretions in proximal and distal airways. This suggests that lectins may be used to obtain information about airway secretory cell composition from respiratory secretions.

Distribution of lectin-binding sites in oxyntic and chief cells of isolated rabbit gastric glands

The distribution of lectin-binding sites in oxyntic and chief cells of isolated rabbit gastric glands was determined with seven fluoresceinated lectins, to ascertain which lectins might best be used in the biochemical characterization of cell membranes and glycoproteins of these two cell types. Oxyntic cell canaliculi were labeled by wheat germ, Helix pomatia, and peanut lectins, suggesting a predominance of N-acetylhexosamines. Tubulovesicles were heavily stained by wheat germ, Helix pomatia, and Ricinus communis I lectins, indicative of N-acetylhexosamine- and galactose-containing glycoconjugates. Diffuse oxyntic cell cytoplasmic staining was observed with the mannose-binding lectin concanavalin A. This lectin, along with wheat germ, soybean, Helix pomatia, and Ricinus communis I lectins, bound to oxyntic cell basolateral membranes, indicating mannose, N-acetylhexosamine, and galactose residues. Chief cell apical membranes were labeled with peanut, Ricinus communis I, Helix pomatia, and Ulex europaeus lectins, suggesting a predominance of N-acetylhexosamine, galactose, and fucose residues. None of the lectins demonstrated any significant affinity for chief cell cytoplasm or basolateral membrane. Ulex europaeus agglutinin-binding sites were additionally concentrated in lateral intercellular spaces. The results of this study indicate that the range of utility of isolated rabbit gastric glands can be expanded to include histochemical work. In addition, the data suggest the applicability of lectin affinity chromatography in the isolation and characterization of oxyntic and chief cell membranes and glycoproteins.