Production and characterization of mouse ureteric bud cell-specific rat hybridoma antibodies utilizing subtractive immunization and high-throughput screening

The highly branched collecting system of the kidney arises developmentally from the ureteric bud (UB) by a process of branching morphogenesis. This process is critical for the normal development of the collecting ducts and pelvis of the kidney, and is tightly controlled by the spatial and temporal expression of numerous proteins. To identify cell proteins that are differentially expressed by the UB relative to those expressed by the highly differentiated collecting ducts of the adult kidney, two mouse cell populations derived from either the early UB or the adult inner medullary collecting duct (IMCD) were used. A subtractive immunization strategy was performed in rats to generate monoclonal antibodies that preferentially reacted with antigens on UB, but not IMCD cells. In addition, the technique of antibody printing, a novel high-throughput antibody screening method for determining the specificities of a large number of monoclonal antibodies, is described. The methodologies outlined in this manuscript have broad applicability as they demonstrate that subtractive immunization can be performed in rats with cells derived from mice. Additionally, the high-throughput screening methods should facilitate the use of subtractive immunization for identifying antibodies that can distinguish differences in proteins expressed in closely related cell types.

Acute endotoxemia in rats induces down-regulation of V2 vasopressin receptors and aquaporin-2 content in the kidney medulla

BACKGROUND

Endotoxemia can lead to fluid metabolism alterations despite unchanged or elevated plasma vasopressin (VP) levels, suggesting a refractoriness of the kidney to the effect of the peptide. To test this hypothesis, we examined the effect of lipopolysaccharide (LPS) injection on the expression of V2 receptors and aquaporin-2 in the kidney.

METHODS

Plasma VP and urine osmolality, and binding of [3H]VP to kidney membranes, Western blot, and immunohistochemical analysis of aquaporin-2, in situ hybridization for V2 VP receptors and cytokines mRNAs were measured in the kidney 3 to 24 hours after LPS injection, 250 microg/100 g, intraperitoneally.

RESULTS

LPS injection caused prolonged decreases in urine osmolality (up to 24 hours) without significant changes in plasma levels of sodium or VP. This was associated with marked decreases in V2 VP receptor mRNA and VP receptor number in the kidney, which were evident for up to 12 hours after LPS injection. Aquaporin-2 in kidney inner medulla was also reduced by about 50%. LPS induced interleukin (IL)-1beta in the kidney medulla by 3 hours, reached maximum at 6 hours, and started to decline by 12 hours, while it increased IL-6 mRNA significantly only at 3 hours. Interleukin mRNA expression was absent in kidneys of control rats. In vitro incubation of kidney medulla slices with IL-1beta reduced VP binding.

CONCLUSION

The inflammatory response to acute endotoxemia down regulates V2 VP receptors and aquaporin-2 of the kidney inner medulla resulting in prolonged impairment of the renal capacity to concentrate urine.

Expression of the progesterone receptor and progesterone- metabolising enzymes in the female and male human kidney

Due to high binding affinity of progesterone to the human mineralocorticoid receptor (hMR), progesterone competes with the natural ligand aldosterone. In order to analyse how homeostasis can be maintained by mineralocorticoid function of aldosterone at the MR, especially in the presence of elevated progesterone concentrations during the luteal phase and pregnancy, we investigated protective mechanisms such as the decrease of free progesterone by additional binding sites and progesterone metabolism in renal cells. As a prerequisite for sequestration of progesterone by binding to the human progesterone receptor (hPR) we demonstrated the existence of hPR expression in female and male kidney cortex and medulla at the level of transcription and translation. We identified hPR RNA by sequencing the RT-PCR product and characterised the receptor by ligand binding and scatchard plot analysis. The localisation of renal hPR was shown predominantly in individual epithelial cells of distal tubules by immunohistology, and the isoform hPR-B was detected by Western blot analysis. As a precondition for renal progesterone metabolism, we investigated the expression of steroid-metabolising enzymes for conversion of progesterone to metabolites with lower affinity to the hMR. We identified the enzyme 17alpha-hydroxylase for renal 17alpha-hydroxylation of progesterone. For 20alpha-reduction, different hydroxysteroid dehydrogenases (HSDs) such as 20alpha-HSD, 17beta-HSD type 5 (3alpha-HSD type 2) and 3alpha-HSD type 3 were found. Further, we detected the expression of 3beta-HSD type 2 for 3beta-reduction, 5alpha-reductase (Red) type 1 for 5alpha-reduction, and 5beta-Red for 5beta-reduction of progesterone in the human kidney. Therefore metabolism of progesterone and/or binding to hPR could reduce competition with aldosterone at the MR and enable the mineralocorticoid function.

Urinary antigens as markers of papillary toxicity. II: Application of monoclonal antibodies for the determination of papillary antigens in rat urine

We have previously reported the preparation of monoclonal antibodies specific for antigens localized in the rat renal papilla. Three of the monoclonal antibodies reacting with antigens localized in papillary and cortical collecting duct epithelia were selected for the development of enzyme-linked immunosorbent assay (ELISA)-type assays. The papillary antigens ('PapA') determined in these tests were designated PapAl (applying the monoclonal antibody PapX 5C10), PapA2 (applying the monoclonal antibody PapX 12F6), and PapA3 (applying the monoclonal antibody PapXI 3C7). Using these assays antigen excretion was determined in the urine of rats. Depending on the test compound used. the application route, and the dose, the observed antigen release patterns differed. Whereas after a single intraperitoneal application of 2-bromoethanamine or of propyleneimine an increased release of PapA1 but not of the two other antigens was observed oral application of bromoethanamine had minor effects. In contrast, both a single intraperitoneal application or repeated oral applications of indomethacin resulted in an increased release of all the three antigens. Daily application of ipsapirone in the diet or in drinking water resulted in significantly elevated urinary release of PapAl which increased incrementally for the duration of the application. Release of PapA2 and PapA3 was not affected and remained in the normal range. These results show that with the tests developed changes in the rat renal papilla caused by xenobiotics can be detected early by urinary analysis and monitored during follow-up studies. Moreover. the different antigen release patterns obtained after application of the different compounds suggest a possible differing mode of action.

Modulatory proteins and processes in alliance with immune cells, mediators, and extracellular proteins in renal interstitial fibrosis

A synopsis of the many aspects and factors that contribute to renal tubulo-interstitial fibrosis is presented. The role of fibrogenic cytokines and the conversion of fibroblasts to myofibroblasts are described. It is emphasized that oxygen radicals cause fibroblasts to generate collagen. The properties of those accessory modulatory proteins that affect the behavior of cells in the interstitium are considered and how matrix for ensuing fibrosis is laid down. Understanding the extracellular matrix proteins and these modulatory proteins is important because their behavior can now be modified by means of antisense oligonucleotides.

Attenuation of renomedullary phospholipase C isozyme, PLC-delta 1, in spontaneously hypertensive rats

The distributional patterns of PLC isozymes within the kidney were investigated using spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats at 4 and 12 weeks of age. PLC-beta 1, PLC-beta 3 and PLC-delta 1 quantified by Western blot analysis, were present in the highest concentrations in the inner medulla of rats at both 4 and 12 weeks of age. On the other hand, PLC-beta 4, PLC-gamma 1 and PLC-gamma 2 were distributed almost equally among the regions for the rats of both ages. When compared with WKY rats at 12 weeks of age, the amounts of PLC-beta 1, PLC-beta 3, PLC-gamma 1, PLC-gamma 2, and PLC-delta 1 in the inner medulla of SHRs were significantly lower, and the amount of PLC-delta 1 in the inner stripe of the outer medulla was also significantly lower. Even at the prehypertensive stage at 4 weeks of age, the inner medullary concentration of PLC-delta 1 was significantly lower in SHRs than WKY rats. These results suggest that PLC-delta 1 would play an important role in the development of hypertension.

Urinary antigens as markers of papillary toxicity. I. Identification and characterization of rat kidney papillary antigens with monoclonal antibodies

Monoclonal antibodies were prepared in an attempt to develop diagnostic tools for the identification of toxic damage to the rat renal papilla. One IgG and five IgM monoclonal antibodies, reacting with antigens localized in the papilla were obtained. Three of the IgM class and the IgG class monoclonal antibodies were found to be specific for antigens localized in collecting ducts, two of them staining papillary collecting ducts more intensely than cortical collecting ducts. The IgG class antibody, termed Pap X 5C10, recognizes an antigen located at high density on the luminal side of papillary collecting duct epithelial cells and at lower density in cortical collecting duct cells. One of the IgM class monoclonal antibodies reacts with an antigen localized in epithelial cells as ascending and descending loops of Henle and of connecting tubules. Another of the IgM class monoclonal antibodies reacts with an antigen localized in the interstices of the inner medulla. All these monoclonal antibodies react with their antigens in native frozen as well as in Bouin-fixed and paraffin-embedded tissue slices. Molecular properties of the Pap X 5C10 antigen have been investigated by gel permeation chromatography, SDS-PAGE, Western blotting, and isoelectric focusing. The results indicate that the antigen in both its tissue-derived and urinary form is of large (150-200 kDa) molecular size and can be separated into two molecular species with isoelectric points of pH 7.2 and 7.3 respectively. In the urine the antigens recognized by the monoclonal antibodies form large complexes with Tamm-Horsfall protein. The antigen-containing complexes can be extracted from urine by adsorption to diatomaceous earth and elution with SDS-containing buffer. Using sandwich ELISA-type assays it is possible to determine the concentration of the antigens. In preliminary experiments we were able to show that at least three of the antigens are detected in the urine following toxic insults to the kidney. The monoclonal antibodies prepared and the tests developed thus may provide direct diagnostic access to the renal papilla and allow, for the first time, early detection of papillary damage.

Necrotizing medullary lesions in patients with ANCA associated renal disease

One hundred and five renal specimens from patients with antineutrophil cytoplasmic antibody and antiglomerular basement membrane antibody-associated diseases were reviewed for necrotizing lesions involving the renal medulla. Necrotizing medullary lesions were identified in eight of 56 cases in which medullary tissue was present. All eight were in patients with antineutrophil cytoplasmic antibody (ANCA) associated disease (seven, C-ANCA; one P-ANCA). Four types of medullary lesions were identified; necrotizing capillaritis (seven cases), necrotizing arteriolitis (two cases), pathergic granulomas (three cases) and papillary tip necrosis (one case). Both medullary arteriolitis and medullary peritubular capillaritis developed without corresponding cortical arteriolitis or cortical peritubular capillaritis. Although necrotizing glomerulonephritis was present in seven of eight patients, its activity did not parallel the severity of the medullary lesions. We conclude that several forms of necrotizing medullary vascular lesions may develop in ANCA-associated disease and that there is discordance between state of activity and types of vessel affected between cortical and medullary vascular compartments.

Prostaglandin H synthase immunoreactivity localized by immunoperoxidase technique (PAP) in the small intestine and kidney of rabbit and guinea-pig

Prostaglandins and inhibitors of prostaglandin synthesis have striking regulatory effects on intestinal muscularis externa. We suggested earlier that a population of macrophage-like cells, located between the external muscle layers might release prostaglandins with a local effect on enveloping interstitial cells of Cajal, postulated pacemaker cells of the gut. To determine cellular production site(s) of prostaglandin we applied monoclonal antibodies against prostaglandin H synthase combined with the PAP technique to sections of rabbit and guinea-pig small intestine and kidney. In rabbit small intestine muscle cells in the circular muscle layer and in the muscularis mucosae were positive, longitudinal muscle negative. Vascular endothelial cells and serosal mesothelial cells were stained. In guinea-pig all muscle layers were unstained but endothelial and mesothelial cells were stained together with unidentified cells in the outermost submucosa. In rabbit kidney, positive staining of collecting ducts, interstitial cells, the parietal layer of Bowman's capsule and arterial endothelial cells was present. Furthermore, we found prostaglandin synthase antigenicity in the epithelial cells lining the loop of Henle, not described before. In guinea-pig medullary collecting ducts were stained and the papilla was lined by stained epithelial cells. The results show a species variation in the distribution of recognizable levels of prostaglandin H synthase. The impressive reaction in the mesothelium must be considered, when enzyme distribution is examined biochemically with fractionated tissue. Our findings do not support our hypothesis that macrophage-like cells are more potent sources of prostaglandins than smooth muscle cells.

Expression of binding sites for Dolichos biflorus agglutinin at the apical aspect of collecting duct cells in rat kidney

To identify precisely the structural and functional cell type in the collecting duct of the rat kidney expressing binding sites for Dolichos biflorus agglutinin (DBA), we stained serial paraffin sections of kidney with horseradish peroxidase-labeled DBA and with immunocytochemical methods for localizing (Na+ + K+)-ATPase and carbonic anhydrase II (CA II), enzymes found preferentially in principal and intercalated cells, respectively. Most principal cells expressing a strong basolateral staining for (Na+ + K+)-ATPase showed binding sites for DBA at their luminal surfaces. However, a minority of cells rich in CA II and showing morphologic characteristics of intercalated cells also expressed DBA binding sites at their luminal surface and apical cytoplasm. These data suggest that DBA cytochemistry can provide a useful tool for studying the functional polarity of the main cell types of the collecting duct of the rat kidney.

[A new serologic reaction in patients with polymyalgia rheumatica and/or giant cell arteritis]

Fresh sera from patients with active polymyalgia rheumatica and/or giant cell arteritis are fixing the complement components C4 and C3 to structures of the medulla of rat kidney tissue as demonstrated by the indirect immunofluorescent technique. This PMR-associated reaction is also a useful tool in monitoring disease activity, as it becomes negative under effective treatment with steroids.

Renal and systemic kappa light chain deposits and their plasma cell origin identified by immunoelectron microscopy

Kappa light chain determinants were identified by immunoelectron microscopy in nodular glomerulosclerotic lesions and systemic interstitial deposits from a man who died several years after the onset of proteinuric renal failure treated by hemodialysis. He developed adrenal and hepatic failure preterminally but not overt malignant myeloma. Specific labeling was most concentrated over the inner aspect of glomerular basement membrane and the mesangium, which suggested that the protein was nonfiltrable. Tubular basement membrane labeling was densest over the outer aspect, which suggested that the protein perfused from the interstitium rather than from the tubular lumen. We identified the source of the protein as a population of plasma cells present within bone marrow and renal interstitium; these showed specific immunogold labeling for kappa light chain protein over organelles concerned with protein synthesis, secretion, and storage. This appears to be the first identification of light chain determinants in human interstitial para-amyloid deposits with the use of immunogold ultrastructural techniques in tissues prepared for electron microscopy by standard methods and stored as epoxy resin blocks.

Mononuclear phagocyte system of the mouse defined by immunohistochemical localization of antigen F4/80. Identification of resident macrophages in renal medullary and cortical interstitium and the juxtaglomerular complex

Macrophages have been identified in mouse kidney by immunohistochemical localization of the macrophage-specific antigen F4/80. They constitute the majority of the renal medullary interstitial cell population and are also found in contact with cortical distal and proximal tubules and Bowman's capsule. They are a physical component of the juxtaglomerular complex.

Major histocompatibility complex antigens in rat kidney, ureter, and bladder. Localization with monoclonal antibodies and demonstration of Ia-positive dendritic cells

Monoclonal mouse xenoantibodies to the SD and part of the Ia antigen complex of the rat major histocompatibility complex (MHC) were raised, and used to localize MHC antigens on frozen sections of kidney, ureter, and bladder of the DA rat strain. The Ia antigens recognized by our monoclonal antibody were located almost entirely within the cells of some, probably the proximal, convoluted tubules of the kidney. The only other Ia-bearing structures were intensely Ia-positive dendritic cells found predominantly in the renal cortex and in the mucosal connective tissues of the ureter and bladder. The SD antigens were widely distributed in the kidney with a major portion again located within the tubular cells, although in the case of SD antigens all tubular cells, including those of the medulla, were positive. By far the brightest tubules were clusters in the outer medulla, probably representing the thick loops of Henle. The endothelium of arterioles, venules and glomerular and interstitial capillaries all stained very brightly for SD antigens. The glomerular mesangium and the interstitial connective tissues of the kidney, ureter, and bladder all gave diffuse positive staining for SD antigens. Transplantation studies established that the tubular Ia and SD antigens of the kidney are produced by the cells and are not in the process of excretion or reabsorption.

Distribution of blood group antigen A in normal and pathologic human kidneys

We tested this distribution with an indirect immunofluorescent technique using purified rabbit anti-A antiserum on 21 whole normal kidneys (a group, N equal to 18; AB group, N equal to 1; O group, N equal to 2) and on 349 kidney biopsy samples (A group, N equal to 140; AB group, N equal to 14; O or B group, N equal to 195) representing a large spectrum of renal diseases. In normal kidneys from A and AB groups, the A antigen was detected in the whole vascular endothelium and in the convoluted distal tubules. In secretors, collecting tubules were brightly positive. Epithelial staining was more diffuse in the inner part than it was in the outer part of the medulla. The basement membrane of the inner collecting tubules was positive in frozen sections but not in paraffin sections. In pathologic kidneys, modifications were obvious: (1) The thickened basement membrane of atrophic convoluted distal tubules was brightly stained. (2) Endothelial staining allowed a precise appreciation of the glomerular and interstitial vasculature. (3) In proliferative changes such as arterial intimal proliferation, proliferative glomerulonephritis, and interstitial cell infiltration, endothelial cells do not proliferate. This routine staining technique of endothelial cells by anti-A antiserum provide information not obtainable with light microscopy.

Accelerated immune complex nephritis due to mesangial overloading in spontaneous hypertensive (SHR) rats

Immune complex nephritis induced by bovine serum albumin (BSA) and horseradish peroxidase (HRP) was superimposed upon spontaneous hypertensive rats (SHR rats) which were pretreated with polyvinyl alcohol (PVA). PVA accumulated predominantly in the mesangium, and the superimposed nephritis developed more accelerated glomerular damage with marked capillary deposition of immune complexes than control animals which were not pretreated with PVA.

Depression of the T-lymphocyte response to phytohaemagglutinin by renal cells

The lymphocytic infiltrate in the renal parenchyma is a consistent histological feature of pyelonephritis, but the role of the lymphocytes in the immunobiology of pyelonephritis is not known. In this investigation the influence of the local environment on the potential function of T lymphocytes in the kidney was investigated. The experiments have demonstrated that the response of rat lymphocytes to stimulation in vitro with phytohaemagglutinin (PHA) can be entirely ablated by normal kidney cells. Even when the number of kidney cells added to cultures of lymphocytes was less than 2% of the cells present some ablation of T-lymphocyte function could be detected. The biological characteristics of the factor causing ablation of the PHA responsiveness of T lymphocytes were partially characterized and the factor appears to have unique features that differentiate it from lymphocyte chalones and other tissue factors influencing lymphocyte function. The results may explain recent findings where T lymphocytes were found to be the predominant lymphocyte in the inflammatory infiltrate but were not responsive to PHA in vitro.

Anti-streptococcal antibodies reacting with brain tissue. I. Immunofluourescent studies

Serum JD from a 14-year old girl with Sydenhams chorea contained antibodies which gave immunofluorescent staining of the limiting membrane of the brain, ependymal tissue and fibrous astrocytes. These antibodies could be completely absorbed by Str. pyogenes type 24 (NCTC 8305) but only partially if at all by type 6 matt (NCTC 8302) or type 6 glossy (NCTC 8709). In contrast, staining by the same serum of the choroid plexus, the periphery of hepatocytes, the periphery of the cells of the gastric mucosa, and tubules in the kidney could be absorbed out by the type 6 matt and type 24 strains (but not by the type 6 glossy or Staph. aureus NCTC 6571). A rabbit anti-streptococcal serum (3/74) raised against disintegrated washed cells of Str. pyogenes type 24 stained and the same structures in the brain to high titre, but not the choroid plexus and not the other structures stained by serum JD. These staining reactions of 3/74 could be absorbed out by Str. pyogenes type 24 but not by Str. pyogenes type 6 matt or type 6 glossy. None of these staining patterns given by serum JD or by 3/74 could be absorbed by human uterine smooth muscle. Serum 3/74 stained heart muscle but this reaction could be absorbed without affecting the brain staining reactions. Sera from 4 other patients with Sydenham's chorea were found to give staining of the ependyma and the limiting membrane, 2 only very weakly.