Phage-derived lysins as potential agents for eradicating biofilms and persisters

Bacterial biofilms are highly resistant to the action of antibiotics. Presence of persisters, phenotypically resistant populations of bacterial cells, is thought to contribute toward recalcitrance of biofilms. The phage-derived lysins, by virtue of their ability to cleave the peptidoglycan of bacterial cells in an enzymatic manner, have the unique ability to kill dormant cells. Several lysins have shown potent antibiofilm activity in vitro. The fact that lysins have shown better efficacy than conventional drugs in animal models of endocarditis and other infections involving biofilms suggests that the lysins can potentially be developed against difficult-to-treat bacterial infections.

Post-Synthetic Defucosylation of AGP by Aspergillus nidulans α-1,2-Fucosidase Expressed in Arabidopsis Apoplast Induces Compensatory Upregulation of α-1,2-Fucosyltransferases

Cell walls are essential components of plant cells which perform a variety of important functions for the different cell types, tissues and organs of a plant. Besides mechanical function providing cell shape, cell walls participate in intercellular communication, defense during plant-microbe interactions, and plant growth. The plant cell wall consists predominantly of polysaccharides with the addition of structural glycoproteins, phenolic esters, minerals, lignin, and associated enzymes. Alterations in the cell wall composition created through either changes in biosynthesis of specific constituents or their post-synthetic modifications in the apoplast compromise cell wall integrity and frequently induce plant compensatory responses as a result of these alterations. Here we report that post-synthetic removal of fucose residues specifically from arabinogalactan proteins in the Arabidopsis plant cell wall induces differential expression of fucosyltransferases and leads to the root and hypocotyl elongation changes. These results demonstrate that the post-synthetic modification of cell wall components presents a valuable approach to investigate the potential signaling pathways induced during plant responses to such modifications that usually occur during plant development and stress responses.

Tobacco arabinogalactan protein NtEPc can promote banana (Musa AAA) somatic embryogenesis

Banana is an important tropical fruit worldwide. Parthenocarpy and female sterility made it impossible to improve banana varieties through common hybridization. Genetic transformation for banana improvement is imperative. But the low rate that banana embryogenic callus was induced made the transformation cannot be performed in many laboratories. Finding ways to promote banana somatic embryogenesis is critical for banana genetic transformation. After tobacco arabinogalactan protein gene NtEPc was transformed into Escherichia coli (DE3), the recombinant protein was purified and filter-sterilized. A series of the sterilized protein was added into tissue culture medium. It was found that the number of banana immature male flowers developing embryogenic calli increased significantly in the presence of NtEPc protein compared with the effect of the control medium. Among the treatments, explants cultured on medium containing 10 mg/l of NtEPc protein had the highest chance to develop embryogenic calli. The percentage of lines that developed embryogenic calli on this medium was about 12.5 %. These demonstrated that NtEPc protein can be used to promote banana embryogenesis. This is the first paper that reported that foreign arabinogalactan protein (AGP) could be used to improve banana somatic embryogenesis.

Structural and biochemical characterization reveals LysGH15 as an unprecedented "EF-hand-like" calcium-binding phage lysin

The lysin LysGH15, which is derived from the staphylococcal phage GH15, demonstrates a wide lytic spectrum and strong lytic activity against methicillin-resistant Staphylococcus aureus (MRSA). Here, we find that the lytic activity of the full-length LysGH15 and its CHAP domain is dependent on calcium ions. To elucidate the molecular mechanism, the structures of three individual domains of LysGH15 were determined. Unexpectedly, the crystal structure of the LysGH15 CHAP domain reveals an “EF-hand-like” calcium-binding site near the Cys-His-Glu-Asn quartet active site groove. To date, the calcium-binding site in the LysGH15 CHAP domain is unique among homologous proteins, and it represents the first reported calcium-binding site in the CHAP family. More importantly, the calcium ion plays an important role as a switch that modulates the CHAP domain between the active and inactive states. Structure-guided mutagenesis of the amidase-2 domain reveals that both the zinc ion and E282 are required in catalysis and enable us to propose a catalytic mechanism. Nuclear magnetic resonance (NMR) spectroscopy and titration-guided mutagenesis identify residues (e.g., N404, Y406, G407, and T408) in the SH3b domain that are involved in the interactions with the substrate. To the best of our knowledge, our results constitute the first structural information on the biochemical features of a staphylococcal phage lysin and represent a pivotal step forward in understanding this type of lysin.

The staphylococcal phage lysin LysGH15 demonstrates great potential against methicillin-resistant Staphylococcus aureus (MRSA). Here, we report that the lytic activity of LysGH15 and its CHAP domain is dependent on calcium ions. To elucidate the molecular mechanism, we determined the structures of three individual LysGH15 domains using X-ray crystallography or nuclear magnetic resonance (NMR). The crystal structure unexpectedly reveals an “EF-hand-like” calcium-binding site near the Cys-His-Glu-Asn quartet active site groove in the LysGH15 CHAP domain. Furthermore, the calcium ion plays an important role as a switch that modulates the lytic activity of the CHAP domain. Additionally, structure-guided mutagenesis also confirms that both E282 and the zinc ion play an important role in maintaining the lytic activity of the LysGH15 amidase-2 domain. Moreover, the NMR structure and titration-guided mutagenesis identify residues in the LysGH15 SH3b domain that are involved in the interactions with the substrate. The structure of LysGH15 is the first determined lysin structure from a staphylococcal phage, and these results represent a pivotal step forward in understanding this type of lysin.

Degradation of methicillin-resistant Staphylococcus aureus biofilms using a chimeric lysin

Methicillin-resistant Staphylococcus aureus (MRSA) is responsible for a large number of chronic infections due to its ability to form robust biofilms. Herein, the authors evaluated the anti-biofilm activity of a Staphylococcus specific chimeric lysin ClyH on MRSA biofilms. ClyH is known to be active against planktonic MRSA cells in vitro and in vivo. The minimum concentrations for biofilm eradication (MCBE) of ClyH were 6.2-50 mg l(-1), much lower than those of antibiotics. Scanning electron microscope (SEM) analysis revealed that ClyH eliminated MRSA biofilms through cell lytic activity in a time-dependent manner. Viable plate counts and kinetic analysis demonstrated that biofilms of different ages displayed varying susceptibility to ClyH. Together with previously demonstrated in vivo efficacy of ClyH against MRSA, the degradation efficacy against biofilms of different ages indicates that ClyH could be used to remove MRSA biofilms in vivo.

Effect of arabinogalactan proteins from the root caps of pea and Brassica napus on Aphanomyces euteiches zoospore chemotaxis and germination

Root tips of many plant species release a number of border, or border-like, cells that are thought to play a major role in the protection of root meristem. However, little is currently known on the structure and function of the cell wall components of such root cells. Here, we investigate the sugar composition of the cell wall of the root cap in two species: pea (Pisum sativum), which makes border cells, and Brassica napus, which makes border-like cells. We find that the cell walls are highly enriched in arabinose and galactose, two major residues of arabinogalactan proteins. We confirm the presence of arabinogalactan protein epitopes on root cap cell walls using immunofluorescence microscopy. We then focused on these proteoglycans by analyzing their carbohydrate moieties, linkages, and electrophoretic characteristics. The data reveal (1) significant structural differences between B. napus and pea root cap arabinogalactan proteins and (2) a cross-link between these proteoglycans and pectic polysaccharides. Finally, we assessed the impact of root cap arabinogalactan proteins on the behavior of zoospores of Aphanomyces euteiches, an oomycetous pathogen of pea roots. We find that although the arabinogalactan proteins of both species induce encystment and prevent germination, the effects of both species are similar. However, the arabinogalactan protein fraction from pea attracts zoospores far more effectively than that from B. napus. This suggests that root arabinogalactan proteins are involved in the control of early infection of roots and highlights a novel role for these proteoglycans in root-microbe interactions.

Arabinogalactan-proteins stimulate the organogenesis of guard cell protoplasts-derived callus in sugar beet

Arabinogalactan proteins (AGPs) represent a class of proteoglycans implicated in the development and differentiation of cells and tissues both in planta and in vitro. Here we report that AGP-rich extracts isolated from media of embryogenic and non-embryogenic suspension cultures of sugar beet (Beta vulgaris L.) are able to enhance the organogenesis of guard protoplast-derived callus and to increase the number of shoots formed, in comparison to control cultures. Immunocytochemical detection of carbohydrate antigens in the extracts revealed the presence of epitopes that typify both AGP and pectin, the latter being frequently bound to AGPs or, in some cases, even contributing to the polysaccharide structure of proteoglycan molecules. The most abundant epitopes proved to be those recognized by the JIM13, LM2, and MAC207 antibodies, whereas some others could be found only in relatively small or trace amounts--these included epitopes recognized by JIM16, JIM5, and LM6. Surprisingly, the JIM4- and JIM8-binding epitopes that are expressed in the course of in vitro morphogenetic processes of many species could not be detected at all in sugar beet AGPs. This is the first report of the improvement of sugar beet protoplast-derived callus organogenesis by exogenous AGP-rich extracts, an achievement that will have great impact on the biotechnological applications of protoplast technology in this species.

Immunomodulatory effects of arabinogalactan-proteins from Baptisia and Echinacea

The influences of different arabinogalactan-proteins (AGPs) on proliferation and IgM-production of mouse lymphocytes as well as nitrite- and IL6-production of mouse macrophages were investigated in vitro. AGPs have been isolated and purified from roots of Baptisia tinctoria and Echinacea pallida and suspension culture of Echinacea purpurea. Comparing the AGPs, there are differences with regard to fine structure as well as to activities. AGPs from roots of B. tinctoria and E. pallida show high activity in all test systems. AGP from cell culture of E. purpurea shows no influence on proliferation of mouse lymphocytes, only weak influence on the IgM-production of mouse lymphocytes and weak stimulation of nitrite- and IL6-production in alveolar mouse macrophage culture.

Importance of carbohydrate in the interaction of Tamm‐Horsfall protein with complement 1q and inhibition of classical complement activation

Tamm-Horsfall protein (THP) binds strongly to complement 1q (C1q), a key component of the classical complement pathway. The goals of this study were to determine whether THP altered the activation of the classical complement pathway and whether the carbohydrate portion of THP was involved in this glycoprotein's binding to C1q and alteration of complement activation. The ability of THP to prevent complement activation in diluted serum or plasma incubated at 37 degrees C was assessed using both a haemolytic assay with antibody-sensitized sheep RBC and a C4d ELISA. Both these methods showed that THP inhibited activation of the classical complement pathway in a dose-dependent manner. Glycosidases were used to remove most of the carbohydrate from THP. This partially deglycosylated THP bound human IgG with a higher affinity (KD1 = 1.4 nmol/L; KD2 = 0.31 micromol/L) than did intact THP (KD1 = 33.4 nmol/L; KD2 = 31.0 micromol/L). An ELISA showed that removal of carbohydrate from THP reduced, but did not eliminate, the ability of this protein to inhibit binding of C1q to intact THP. Haemolysis assays using antibody-sensitized sheep RBC showed that removal of THP carbohydrate eliminated the ability of THP to protect against complement activation. In conclusion, THP inhibited the activation of the classical complement pathway that occurred in diluted serum or plasma. The carbohydrate moieties of THP appeared to be important in this inhibitory activity.

[Chemical basis of the effects of Tamm-Horsfall protein on the formation of calcium oxalate stones]

Tamm-Horsfall (TH) protein is the most abundant protein in human urine. It plays dual roles in the formation of calcium oxalate stones depending on its structure, concentration and urine properties. In this paper, the chemical basis of the effects of TH protein on the formation of calcium oxalate stones was systematically discussed in view of the concentration of TH protein, the urinary pH, ionic strength, metallic ions, the cooperative effect of citrate and TH protein, and the effect on the adhesion of calcium oxalate crystals to the renal cell membrane. The differentiation between TH protein and its analog was also comparatively discussed.

MAdCAM-1 expression and regulation in murine colonic endothelial cells in vitro

BACKGROUND

Although the mucosal addressin cell adhesion molecule-1 (MAdCAM-1) is associated with the etiology of inflammatory bowel diseases, few studies have directly examined MAdCAM-1 using microvascular endothelium derived from the colon. This study measured the expression of MAdCAM-1 in a novel colon endothelial line MJC-1, as well as MAdCAM-1 regulation and function in vitro.

METHODS

We cloned microvascular endothelial cells from primary colon cultures using ImmortoMice mice (whose cells express a temperature-sensitive SV40 large T antigen, H-2Kb-tsA58 mice). Expression of MAdCAM-1 after stimulation with cytokines [tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, or interferon (IFN)-gamma] was determined by Western blotting. Signal paths regulating MAdCAM-1 expression were examined using pharmacological blockers before cytokines. We also examined lymphocyte adhesion using lymphocytes that constitutively express alpha4beta7 integrin.

RESULTS

TNF-alpha induced MAdCAM-1 in a dose-dependent manner by 24 hours. MAdCAM-1 induction was protein kinase C, tyrosine kinase, p38 mitogen activated protein kinase, and nuclear-factor kappa-B/poly adenosine diphosphate ribose polymerase dependent. Lymphocyte adhesion was increased 2.6-fold after TNF-alpha stimulation and was inhibited by anti-MAdCAM-1 antibody before treatment (P < 0.05 control versus TNF-alpha).

CONCLUSIONS

In vitro, MAdCAM-1 can be induced on colon endothelial cells by TNF-alpha stimulation and may represent a useful model to study microvascular injury in the large intestine.

Focal adhesion kinase in netrin-1 signaling

Netrins are a family of secreted molecules that are important for axonal outgrowth and guidance in the developing nervous system. However, the signaling mechanisms that lie immediately downstream of netrin receptors remain poorly understood. Here we report that the netrin receptor DCC (deleted in colorectal cancer) interacts with the focal adhesion kinase (FAK), a kinase implicated in regulating cell adhesion and migration. FAK was expressed in developing brains and was localized with DCC in cultured neurons. Netrin-1 induced FAK and DCC tyrosine phosphorylation. Disruption of FAK signaling abolished netrin-1-induced neurite outgrowth and attractive growth cone turning. Taken together, these results indicate a new signaling mechanism for DCC, in which FAK is activated upon netrin-1 stimulation and mediates netrin-1 function; they also identify a critical role for FAK in axon navigation.

Effects of Tamm-Horsfall protein on polymorphonuclear leukocyte function

BACKGROUND

Tamm-Horsfall protein (THP), a glycoprotein produced exclusively by renal tubular cells, is thought to be involved in several inflammatory disorders such as bacterial interstitial nephritis as well as in defence against uropathogenic microorganisms. The specific effects of THP on inflammatory cells, however, are not yet well known. Therefore, the present study investigates the effects of THP in its soluble form on distinct polymorphonuclear leukocyte (PMNL) functions.

METHODS

PMNL were isolated from the venous blood of healthy adult donors and incubated at low THP concentrations (70-350 ng/ml), resembling plasma concentrations, and at high THP concentrations (1.75-8.75 micro g/ml), resembling urinary concentrations.

RESULTS

High (urinary) THP concentrations inhibited PMNL apoptosis and chemotaxis and stimulated PMNL phagocytosis, while low (plasma) THP concentrations increased PMNL chemotaxis.

CONCLUSIONS

These data indicate that THP influences several PMNL functions, suggesting a crucial immunomodulatory role for this glycoprotein in host defence mechanisms of the kidney and genitourinary tract.

Effects of Tamm-Horsfall protein on the protection of MCDK cells from oxalate induced free radical injury

Renal cell injury and fixed particle formation is one of the theories of urinary stone formation. The exposure of renal epithelial cells to oxalate ions and calcium oxalate monohydrate crystals can cause free radical generation and increase lipid peroxidation. Tamm-Horsfall protein (THP) has a protective effect on the production of free radicals in vitro. We aimed to show that THP (and its deglycosylated products, D-THP) could protect culture cells from free radical injury in vivo as well as the possible mechanism by which this is done. Exposure of Madin-Darby canine kidney (MDCK) cells to Ox resulted in a significant increase in the release LDH, NBT and MDA, as well as an increase in caspase 3 activity, all of which were further elevated when COM crystals were added. With the addition of THP at 500 nM, there was a significant decrease in the release of LDH and the production of MDA and NBT. A decrease in capase 3 activity was observed when 500 nM THP was added to the culture medium that reached 32.7% and 40.4% of inhibition in CaOx+THP and CaOx+COM+THP, respectively. THP decreased the adhesion of COM crystals to the MDCK cells but lost its effect when THP was deglycosylated. The results indicate that both Ox and COM crystals cause the release of LDH, MDA, NBT and increase the activity of capase 3 in MDCK cells. As a free radical scavenger, THP reduces the amount of free radicals and provides significant protection at a critical concentration of 500 nM. The deglycosylated THP decreased the effect of the protection of the MDCK cells from oxalate-induced injury and an increase of adhesion of the COM crystals to the MDCK cells. Therefore, the effects of THP on the protection of oxalate induced radical injury may be partly due to its intact glycosylation and its adhesion to the cell membrane.

Differentiation between the complement modulating effects of an arabinogalactan-protein from Echinacea purpurea and heparin

Due to the important physiological role of the complement system, complement modulation, either inhibition or stimulation, is an interesting target for drug development. Several plant polysaccharides are known to exhibit complement modulating activities. Sometimes these effects are described as complement inhibition, although the basic mechanism is a stimulation of the complement activation. This misinterpretation is due to the observed reduced haemolysis in the widely used haemolytic complement assay, which does not allow to differentiate between complement activators and inhibitors, when it is performed in the classical manner. The aim of the presented study was to demonstrate that by simple modifications of the classical procedure this assay becomes an efficient tool to distinguish between real complement inhibitors and complement activating compounds without performing expensive, molecular mechanistic investigations. As practical examples heparin with proven complement inhibiting activity and AGP, a new arabinogalacatan-protein type II isolated from pressed juice of the aerial parts of Echinacea purpurea, as a potential complement activating compound were included in the study. By means of varying the preincubation time of the test compound with complement, AGP was clearly identified as a stimulator of both the classical and alternative pathway of complement activation. These findings correspond to the results of molecular mechanistic investigations. Selective removal of the arabinose side chains of AGP resulted in considerably reduced activity. Therefore, the three-dimensional structure of the polysaccharide, i. e., a backbone branched by side chains, is supposed to be important for the interactions with the complement system. The complement activating effects of AGP may contribute to the well-established immunostimulating effects of the pressed juice from Echinacea purpurea. Abbreviations. AGP:arabinogalactan-protein AGP-hydr.:hydrolysed arabinogalactan-protein AP-CA:haemolytic complement assay for the alternative pathway CP-CA:haemolytic complement assay for the classical pathway EGTA-VB:veronal buffered saline containing EGTA and Mg 2+HPS:human pooled serum RT:room temperature LPS:lipopolysaccharide RaE:rabbit erythrocytes RT:room temperature ShE(A):(sensitised) sheep erythrocytes VB:veronal buffered saline containing Ca 2+ and Mg 2+

Interaction of human Tamm-Horsfall glycoprotein with Bordetella pertussis toxin

Tamm-Horsfall glycoprotein (THP), which is synthesized by renal tubular cells, is the most abundant protein in normal human urine. Although its physiological function remains unclear, it has been proposed that THP may act as a defence factor against urinary tract infections by inhibiting the binding of S- and P-fimbriated Escherichia coli to renal epithelial cells. Because THP-related proteins are also found in the superficial layers of the oral mucosa, the authors investigated the ability of THP to interfere with the cytoadherence of pathogenic bacteria that colonize mucosal surfaces other than those of the urogenital tract. In this report, it is shown that THP binds to virulent Bordetella pertussis and reduces its adherence to both renal and pulmonary epithelial cells. This cytoadherence inhibitory effect was not observed with a B. pertussis mutant lacking the pertussis toxin (PTX) operon, and was dependent on the direct interaction of THP with the S2 subunit within the PTX B oligomer. The authors also show that the glycosylation moiety of THP is crucial for its binding to PTX. The THP-PTX interaction was exploited to develop an affinity chromatography method that allows a one-step purification of active PTX. These observations suggest that besides its anti-adherence activity, THP may also trap toxins produced by pathogenic bacteria that colonize mucosal surfaces.

Effects of Tamm-Horsfall protein and albumin on calcium oxalate crystallization and importance of sialic acids

BACKGROUND

Tamm-Horsfall protein and human serum albumin are common urinary proteins that show uncertain inhibitory action on the crystallization of calcium oxalate monohydrate.

MATERIALS AND METHODS

Batch experiments on crystal nucleation, growth, and aggregation were performed using purified Tamm-Horsfall protein and albumin before and after enzymatic removal of sialic acids from the proteins.

RESULTS

At a concentration of 100 nM, both Tamm-Horsfall protein and albumin promoted the time of crystal nucleation by 18.4% and 8.9%, respectively, relative to the control. However, both of the proteins exerted an inhibitory effect on crystal growth, with the IC(50) being 7.27 nM for Tamm-Horsfall protein and 37.5 nM for albumin. The inhibition of crystal aggregation was 81.82% by Tamm-Horsfall protein 100 nM but only 54.55% at 50 nM after enzymatic removal of the sialic acid. Instead of increasing the inhibition, the effect was changed to promotion after an increase in the concentration of Tamm-Horsfall protein to more than 500 nM for native protein and to more than 100 nM for the enzymatic digest. Albumin showed little change after enzymatic treatment and maintained a maximal inhibitory effect of 72.73% on crystal aggregation when the concentration reached to 100 nM.

CONCLUSION

Because the promotion of nucleation could lessen the subsequent saturation of a calcium oxalate solution, it is concluded that Tamm-Horsfall protein and albumin show an overall effect of inhibition on crystallization in vitro. The inhibitory effect of Tamm-Horsfall protein is partly related to sialic acid.

Role of Tamm-Horsfall protein in the binding and in vivo phagocytosis of type 1 fimbriated Escherichia coli by mouse peritoneal macrophages

Tamm-Horsfall glycoprotein (THP) contains manno-oligosaccharides that are recognized by type 1 fimbriae (F1) of Escherichia coli. In the present study, we examined the in vivo phagocytic activity of mouse peritoneal macrophages after treatment of bacteria with THP. At low THP concentrations (12.5 microg/ml and 50 microg/ml) no significant difference was observed in the phagocytosis of E. coli F1+. However, at high THP concentrations (500 microg/ml and 1250 microg/ml) we obtained a reduction of bacterial phagocytosis by mouse peritoneal macrophages.

Role of polymeric Tamm-Horsfall protein in cast formation: oligosaccharide and tubular fluid ions

BACKGROUND

In acute tubular necrosis (ATN), distal tubules are obstructed by casts formed by tubular debris, cells, and Tamm-Horsfall protein (THP). Since there are Arginine-Glycine-Aspartate (RGD) and Leucine-Aspartate-Valine (LDV) adhesive sequences in human THP, there may be direct integrin-mediated binding of tubular cells to THP. Alternatively, polymerization of THP may result in entrapment of the cells in its gel.

METHODS

Adhesion of LLC-PK(1) cells to THP-coated wells was directly measured. THP concentrate was dissolved in solutions which mimic urine from ATN (ATN-S), distal convoluted tubule (DCT-S), collecting duct (CD-S), and monomeric buffer (M buffer). THP was also denatured by either boiling or N-glycanase digestion. Gel formation of THP was then measured. Inhibition of LLC-PK(1) cell adhesion to collagen type I was measured with each solution, as well as after the collagen was pretreated with either monomeric (mTHP) or polymeric (pTHP) THP. The effect of pTHP on the settling rate of LLC-PK(1) cells in suspension was also measured.

RESULTS

LLC-PK(1) cells did not directly adhere to THP, a finding against integrin-mediated binding as a mechanism for in vivo tubular cell/THP cast formation. The high electrolyte concentration of ATN-S and CD-S, however, was associated with pTHP gel formation. Moreover, cells suspended in pTHP remained in suspension. In cell adhesion studies, mTHP attenuated cell adhesion by binding to the matrix, whereas pTHP attenuated cell adhesion by trapping cells in its gel. An active process was involved since both pTHP gel formation and attenuation of cell adhesion were abolished by boiling or oligosaccharide removal with N-glycanase digestion.

CONCLUSIONS

With renal ischemia and proximal tubule cell shedding, ATN and collecting duct fluid composition enhance THP gel formation and thus favor tubular cast formation and obstruction. The present in vitro results indicate the importance of oligosaccharide residues in mediating the effect of the THP on gel formation and potential cast formation in ATN.

Urothelial cytoprotective activity of Tamm-Horsfall protein isolated from the urine of healthy subjects and patients with interstitial cystitis

PURPOSE

Tamm-Horsfall protein (THP) is a ubiquitous urinary protein with essentially no known function. We propose that THP is a cytoprotective agent that protects the urothelium from cationic species. To test this hypothesis we isolated THP from normal and interstitial cystitis urine to see if it could protect cultured cells from damage induced by the polyamine, protamine sulfate (PS).

METHODS

Tamm-Horsfall protein was extracted from the urine of interstitial cystitis (IC) patients (N=28) and normal volunteers (N=5). Urothelial target cells (T24) were radiolabeled with 51Cr and then exposed to PS (0-1.0 mg/mL) for either 1.5 or 20 h. The resulting cytotoxicity data (dose-response curves) were then compared with the data obtained when PS was preincubated with 0-0.5 mg/mL of THP (IC vs normal), the semisynthetic polysaccharide, pentosan polysulfate (Elmiron), or human serum albumin.

RESULTS

Toxicity of PS was significantly reduced by incubation with THP (or Elmiron) prior to evaluation by the chromium release assay, but not reduced by incubating with another protein, albumin. Tamm-Horsfall protein from IC patients' urine was less protective than an equal quantity of THP from normal urine.

CONCLUSIONS

These experiments suggest that THP has an important role in bladder mucosal defense mechanisms, protecting the bladder surface from injury. Inability of THP to prevent cytotoxic damage by urinary polyamine or other urinary toxins (cationic species) may be relevant in the etiology of interstitial cystitis, as putative urinary toxic components have been described in the urine of some patients.

Citrate determines calcium oxalate crystallization kinetics and crystal morphology-studies in the presence of Tamm-Horsfall protein of a healthy subject and a severely recurrent calcium stone former

BACKGROUND

The aim of this study was to measure the effects of normal (nTHP) and abnormal stone former Tamm-Horsfall protein (SF-THP) on calcium oxalate (CaOx) nucleation and aggregation as well as on crystal morphology, in presence or absence of citrate.

METHODS

Nucleation and aggregation of CaOx crystals from a supersaturated, stirred solution (200 mM NaCl, 10 mM Na-acetate, pH 5.70, 5 mM Ca and 0.5 mM Ox) were studied by spectrophotometric time-course measurements of OD at 620 nm (OD(620)). Measured parameters were induction time t(I) (time to induce formation of detectable particles), S(N), (slope of increase of OD(620), mainly due to crystal nucleation), and S(A), (slope of decrease of OD(620) after equilibrium has been reached, due to crystal aggregation). Effects of citrate, nTHP and SF-THP on these parameters were measured, and scanning electron microscopy (SEM) was performed.

RESULTS

At 1.5, 2.5 and 3.5 mM, citrate increased t(I) and inhibited crystal nucleation (by 78-87%) as well as aggregation (by 63-70%), and smaller CaOx crystals (length/width ratio 1.7+/-0.1) than under standard conditions (length/width 3.9+/-0.5) were visible (P<0.001). Normal THP at 30 and 40 mg/l inhibited crystal nucleation and, more strongly, aggregation (inhibition 76-81%). SEM revealed a decrease in length/width ratio to 2.6+/-0.4 (P=0.051 vs standard conditions) and less aggregation than without nTHP. At all concentrations tested, SF-THP reduced t(I) (P=0.0001 vs standard conditions) and promoted aggregation (inhibition -48 to -33%); crystals were elongated with a length/width ratio of 4.3+/-0.6 (P<0. 05 vs nTHP). When simultaneously present with nTHP, citrate enhanced the inhibitory effects of nTHP, producing the smallest (length/width 1.5+/-0.1) and least aggregated crystals. Finally, 3.5 mM citrate turned promotory SF-THP into a crystallization inhibitor with abundant small and clustered, but not aggregated crystals.

CONCLUSION

Citrate appears to be the main determinant of CaOx crystallization rates and crystal morphology in the presence of nTHP as well as SF-THP. Its effects appear to predominate over those of THP, since even promotory SF-THP is turned into a crystallization inhibitor in the presence of citrate. This re-emphasizes at a morphological level what has been concluded from functional as well from clinical studies, namely that citrate is needed in urine at equimolar concentrations to calcium in order to prevent the formation of large crystal aggregates in presence of abnormal THP.

VCAM-1 is more effective than MAdCAM-1 in supporting eosinophil rolling under conditions of shear flow

The ability of the alpha4 integrin counterligands vascular cell adhesion molecule (VCAM)-1 or mucosal addressin (MAd)CAM-1 to support eosinophil rolling or firm adhesion under conditions of physiologic flow has not been delineated. Using a parallel plate flow chamber in vitro and intravital microscopy in vivo, we demonstrate that eosinophil rolling and adhesion on VCAM-1 is mediated by both alpha4beta1 and alpha4beta7 integrins. Eosinophils rolled equally efficiently on both VCAM-1 2 domain and VCAM-1 7 domain, suggesting that the N-terminal 2 domains of VCAM-1 are sufficient to support eosinophil rolling under conditions of flow. Furthermore, activation of the eosinophil beta1 integrin with monoclonal antibody (mAb) 8A2 resulted in both resistance to shear stress-induced detachment from VCAM-1 in vitro and in stable arrest of rolling eosinophils on interleukin (IL)-1beta-stimulated venules in vivo. Eosinophils rolled less efficiently on MAdCAM-1- than on VCAM-1-coated coverslips under conditions of flow. However, eosinophils firmly adhered as efficiently to MAdCAM-1 as to VCAM-1. Overall, these results demonstrate that both VCAM-1 and MAdCAM-1 can support eosinophil firm adhesion under conditions of flow. In contrast, VCAM-1 is significantly more efficient than MAdCAM-1 in supporting eosinophil rolling under conditions of flow. (Blood. 2000;95:592-601)

The dynamic responses of pro-inflammatory and anti-inflammatory cytokines of human mononuclear cells induced by uromodulin

This study was undertaken to examine the dynamic response of human peripheral blood mononuclear cells (PBMC) in the secretion of proinflammatory and anti-inflammatory cytokines induced by uromodulin (URO). Levels of tumor necrosis factor-alpha (TNFalpha), TNF soluble receptor (sTNFRI and II), interleukin 1-beta (IL-1beta), and IL-1 receptor antagonist (IL-1Ra) in the supernatants of URO-stimulated PBMC were measured by ELISA. URO stimulated the secretion of all these cytokines in a dose dependent manner except sTNFRI. Peak levels of TNFalpha and IL-1beta were reached at 6-12 h, while 5-10 fold higher in sTNFR II and IL-1Ra levels were observed at 24-48 h after URO stimulation. URO-induced secretion of TNFalpha, IL-1beta, sTNFRII and IL-1Ra could be enhanced by human plasma. Specifically, serum proteins including C3, sCD14 and IgG not only bound to URO but also enhanced URO-induced TNFalpha secretion of PBMC. Collectively, our data suggest that URO might have dual immunomodulating effect through regulating the secretion of proinflammatory and anti-inflammatory cytokines, and that serum binding proteins might enhance this activity.

Role of calcium oxalate monohydrate crystal interactions with renal epithelial cells in the pathogenesis of nephrolithiasis: a review

Renal tubular fluid in the distal nephron is supersaturated with calcium and oxalate ions that nucleate to form crystals of calcium oxalate monohydrate (COM), the most common crystal in renal stones. How these nascent crystals are retained in the nephron to form calculi in certain individuals is not known. Recent studies from this laboratory have demonstrated that COM crystals can bind within seconds to the apical surface of renal epithelial cells, suggesting one mechanism whereby crystals could be retained in the tubule. Adherence of crystals to cells along the nephron may be opposed by specific urinary anions such as glycosaminoglycans, uropontin, nephrocalcin, and citrate. In culture, adherent crystals are quickly internalized by renal cells, and reorganization of the cytoskeleton, alterations in gene expression, and initiation of proliferation can ensue. Each of these cellular events appears to be regulated by extracellular factors. Identification of molecules in tubular fluid and on the cell surface that determine whether a crystal-cell interaction results in retention of the crystal or its passage out of the nephron appears critical for understanding the pathogenesis of nephrolithiasis.

Effects of Tamm-Horsfall protein with normal and reduced sialic acid content upon the crystallization of calcium phosphate and calcium oxalate in human urine

OBJECTIVE

To examine the effects of Tamm-Horsfall protein (THP) of normal and low sialic acid content on urinary crystallization, and establish whether there are changes conducive to the formation of kidney stones.

MATERIALS AND METHODS

Purified samples of THP were recovered from the urine of non-stone forming individuals. A portion of each THP sample was treated with the enzyme neuraminidase to yield the low sialic acid form of the protein. The two forms of THP were added separately to ultrafiltered urine and crystallization was then induced in the urine by evaporation at 37 degrees C. Two types of experiment were then conducted with the crystals that formed; the rate at which the resulting calcium phosphate or calcium oxalate crystals sedimented in the evaporated urine was determined and the proportion of these crystals and protein which was retained when the urine was passed through a 75 microns sieve was measured.

RESULTS

Calcium phosphate and calcium oxalate crystals remained in stable colloidal suspension in ultrafiltered urine when in the presence of normal THP; these suspensions passed freely through the 75 microns sieves. When crystals formed in the presence of low sialic acid THP, the sedimentation was rapid and the crystals were readily retained with protein on the sieves.

CONCLUSIONS

These results indicate that whilst normal THP inhibits urinary crystal aggregation, the properties of the low sialic acid form are consistent with the promotion of crystal aggregation and hence stone formation.

Involvement of beta 7 integrin and mucosal addressin cell adhesion molecule-1 (MAdCAM-1) in the development of diabetes in obese diabetic mice

Nonobese diabetic (NOD) mice develop autoimmune-mediated lymphocytic inflammation of pancreatic islets (insulitis) that leads to beta-cell destruction and development of diabetes. Inflamed islets show expression of lymphocyte alpha 4 beta 7 integrin and endothelial mucosal addressin cell adhesion molecule-1 (MAdCAM-1), adhesion molecules involved in tissue-selective migration of lymphocytes to mucosal lymphoid tissues. To elucidate the roles of the mucosal lymphocyte/endothelial adhesion system in the development of diabetes, we treated NOD mice with monoclonal antibody against beta 7 integrin or MAdCAM-1. Treatment of mice from age 7 to 28 days or 8 to 12 weeks with either antibody led to significant and long-standing protection against the spontaneous development of diabetes and insulitis. In contrast, neither treatment prevented the development of salivary gland inflammation (sialadenitis), indicating that the effect was tissue-selective. Monoclonal antibody treatment had no demonstrable effect on numbers or phenotypes of peripheral lymphocytes or on the immune response to pancreatic islet or exogenous antigens. These data indicate that lymphocyte and endothelial adhesion molecules involved in the migration of lymphocytes into mucosal lymphoid tissues play a role in the development of diabetes in NOD mice. Moreover, the results suggest that treatment of humans with antibodies against tissue-selective lymphocyte or endothelial adhesion molecules may selectively inhibit the development of autoimmune diseases such as diabetes.

Uromodulin and Tamm-Horsfall protein induce human monocytes to secrete TNF and express tissue factor

Effects of uromodulin (URO) and Tamm-Horsfall protein (THP), the most abundant proteins in the urine of pregnant and normal women, respectively, on the induction of TNF-alpha secretion and tissue factor (TF) expression of human monocytes were studied. THP, URO, and its fragments stimulated human mononuclear cells to proliferate and secrete TNF-alpha. The release of URO and THP-induced TNF-alpha in monocytes was dependent upon protein tyrosine kinase activation that results in tyrosine phosphorylation. URO and THP also induced TF expression of human monocytes and monocytic cell line U937 in a dose-dependent manner. TF expression was transient, reached its peak at 6 h and declined toward basal levels by 24 h. Reverse transcriptase-PCR and dot-blot analysis confirmed the induction of TF mRNA synthesis. URO and THP-induced TF expression were inhibited by actinomycin D and pentoxifylline further supporting the requirement of de novo TF mRNA synthesis. The possibility of LPS contamination of URO and THP was excluded because: 1) URO and THP-induced TF expression were inhibited by specific Ab; 2) URO was less capable of inducing TF in HUVEC as compared with LPS; 3) polymyxin B blocked the induction of Limulus clotting by LPS but not by URO and THP; 4) both LPS-sensitive (C3H/HeN) and -resistant (C3H/HeJ) mice produced little or no TNF-alpha after URO challenge. Therefore, our findings suggest that URO and THP play a significant role in the innate immunity of the urinary system and that the immunostimulatory activity of URO is potentially useful for immunotherapy.

Tamm-Horsfall protein inhibits binding of S- and P-fimbriated Escherichia coli to human renal tubular epithelial cells

Escherichia coli is the predominant pathogen in urinary tract infections. Fimbriae are one of the major virulence factors of these bacteria, since these protein appendices contribute towards bacterial adhesion to epithelial cells. In clinical E. coli isolates from urinary tract infections, P fimbriae are more frequently present than S fimbriae. However, these two types of fimbriae mediate adhesion to cultured tubular epithelial cells equally well. Tamm-Horsfall protein, which is the most abundant protein in normal human urine, inhibits hemagglutination by E. coli expressing S fimbriae, but does not interfere with hemagglutination by P-fimbriated E. coli. Therefore, it has been speculated that Tamm-Horsfall protein may serve as a clearance factor for S-fimbriated E. coli in human urine. In our experiments, adherence of purified S fimbriae and of S-fimbriated E. coli to tubular epithelial cells was inhibited by Tamm-Horsfall protein, but the protein also decreased binding of P-fimbriated E. coli to approximately the same degree. We found less adherence of both types of fimbriae to a Madin-Darby canine kidney cell line expressing soluble and membrane-bound Tamm-Horsfall protein as compared with the control cell line. In conclusion, our in vitro data suggest that urinary Tamm-Horsfall protein may serve as a clearance factor for E. coli expressing both S and P fimbriae. In the light of these findings, the low clinical relevance of S-fimbriated E. coli for urinary tract infections may be readily explained; however, the predominance of P fimbriae remains unresolved.

Tamm-Horsfall glycoprotein (THG) is a binder for surface membrane proteins on blood cells and glomerular mesangial cells

A macromolecule with a molecular weight of 90-100 kDa was purified from normal human pregnancy urine. The molecule was proved to be the Tamm-Horsfall glycoprotein (THG) by Western blot analysis. The macromolecule contains carbohydrate as detected by an enzyme immunoassay. Functionally, the glycoprotein can adhere to and stimulate the thymidine incorporation of human mononuclear cells (MNC) in modest degree via its membranotropic property. In addition to MNC, the protein can also bind to the surface of human polymorphonuclear neutrophils (PMN), red blood cells (RBC) and rat glomerular mesangial cells (RMC). Western blot analysis of various cell lysates with/without proteinase K pretreatment before cell lysis revealed that a 60 kDa and a molecule larger that 94 kDa on the surface of PMN, a 60 kDa protein on MNC and a 32 kDa protein on RBC are the binding molecules for THG. In contrast, many proteins on the surface of RMC could be bound by THG. Immunoprecipitation of membranous iodinated MNC lysates also confirmed that the 60 kDa molecule on MNC is the binding protein for THG. A number of monosaccharide including N-acetylneuraminic acid, N-acetyl-galactosamine, N-acetyl-glucosamine and alpha-methyl-D-mannoside could not inhibit the mitogenic effect of THG on human mononuclear cells. These results suggest that THG is capable of reacting with surface membrane proteins on different cells, but not through the specific carbohydrate-containing lectin-like receptors on the cell surface.

Human glycoprotein HGP92 induces cytokine synthesis in mouse mononuclear phagocytes

HGP92 has been shown to enhance in vitro and in vivo the bactericidal and tumoricidal activity of mouse macrophages. In this study we investigated the effect of HGP92 on the accumulation of cytokine mRNA in mouse inflammatory, peritoneal macrophages and the monocytic cell line J774. HGP92 significantly enhanced the level of cytokine mRNA for IL-1 alpha, IL-1 beta, IL-6, IL-10, IL-12, TNF-alpha and GM-CSF during the first 24 h of the incubation. This effect triggered by HGP92 was comparable to that obtained with lipopolysaccharide (LPS), which is a strong cytokine inducer. This accumulation of cytokine mRNA in macrophages was correlated with secretion of IL-6 and TNF-alpha in cell supernatant. The release of IL-6 was HGP92 concentration dependent over a range of 0.3-10 micrograms/ml with a maximum production obtained after a 24 h incubation of inflammatory macrophages with HGP92. This effect was shown not to be due to contamination of HGP92 by LPS since inflammatory macrophages from C57BL/6 mice were responsive to HGP92 pretreated with polymyxin B sulfate and unresponsive to heated HGP92. Stimulating activity of HGP92 was confirmed using macrophages from C3H/HeJ mice. These results suggest that HGP92 might modulate the immune responses by increasing cytokine production by macrophages.

Crystal structure and subunit dynamics of the abalone sperm lysin dimer: egg envelopes dissociate dimers, the monomer is the active species

Lysin is a 16-kD acrosomal protein used by abalone spermatozoa to create a hole in the egg vitelline envelope (VE) by a nonenzymatic mechanism. The crystal structure of the lysin monomer is known at 1.9 A resolution. The surface of the molecule reveals two tracks of basic residues running the length of one surface of the molecule and a patch of solvent-exposed hydrophobic residues on the opposite surface. Here we report that lysin dimerizes via interaction of the hydrophobic patches of monomers. Triton X-100 dissociates the dimer. The crystal structure of the dimer is described at 2.75 A resolution. Fluorescence energy transfer experiments show that the dimer has an approximate KD of 1 microM and that monomers exchange rapidly between dimers. Addition of isolated egg VE dissociates dimers, implicating monomers as the active species in the dissolution reaction. This work represents the first step in the elucidation of the mechanism by which lysin enables abalone spermatozoa to create a hole in the egg envelope during fertilization.

Characterization of T cell ligands for uromodulin: a possible role in costimulation

In this study, we demonstrate that uromodulin (UMN) is a costimulator of T cells and characterize the T cell ligand which might mediate its costimulatory effect. UMN is an 85-kDa human urinary glycoprotein which is better known for its ability to suppress antigen-induced proliferation of peripheral blood mononuclear cells. It also has a mitogenic effect on peripheral blood cells, which has not been investigated. In this study, costimulation of T cells by UMN is observed only in the absence of B cells and antigen-specific antiserum. Using ligand binding assays we also demonstrate a specific receptor for UMN on peripheral blood T cells and T cell lines (Kd of 10(-8)). We describe two uromodulin binding proteins of approximate M(r) 35 and 55 kDa, isolated from detergent extract of T cells, either of which may represent a receptor for UMN or an associated signal transduction molecule involved in the stimulatory effect of UMN on T cells. Finally, we demonstrate a similar protein in a renal cell line, which may clarify the renal role of UMN.

Tamm-Horsfall mucoprotein reduces promotion of calcium oxalate crystal aggregation induced by urate in human urine in vitro

1. Increasing the concentration of dissolved urate promotes calcium oxalate crystallization in urine from which Tamm-Horsfall mucoprotein, an inhibitor of calcium oxalate crystal aggregation, has almost completely been removed. This study aimed to determine whether the effect of urate could be reduced or abolished by a physiological concentration of Tamm-Horsfall mucoprotein. This was approached in two ways. 2. The effect of Tamm-Horsfall mucoprotein on calcium oxalate crystallization induced by urate was tested in ultrafiltered (10 kDa) urine samples from 10 healthy men. Tamm-Horsfall mucoprotein (35 mg/l) was added to half of each specimen, the urate concentration was increased by the addition of sodium urate solution and crystallization was induced by a standard load of oxalate. The remainder of each urine specimen was used as a control; these specimens were treated with an identical amount of urate solution, but contained no Tamm-Horsfall mucoprotein. Tamm-Horsfall mucoprotein had no effect on the urinary metastable limit or on the deposition of calcium oxalate, but significantly reduced the size of the particles precipitated. 3. The effect of increasing the urate concentration in the presence of Tamm-Horsfall mucoprotein was tested. Tamm-Horsfall mucoprotein (35 mg/l) was added to 10 ultrafiltered urine samples as before, the samples were divided, and the concentration of urate was increased in half of each specimen. Compared with the control to which no urate was added, urate significantly reduced the amount of oxalate required to induce spontaneous calcium oxalate nucleation and increased the median volume and the particle size of the material deposited.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Tamm-Horsfall glycoprotein and albumin on struvite crystal growth in urine of cats

Tamm-Horsfall protein (THP) was isolated and purified, using pooled urine collections from clinically normal cats. The effects of feline THP and purified feline serum albumin on urine chemical and struvite crystal variables were compared, using an in vitro crystal growth system and 24-hour samples of pooled urine obtained from 4 cats. Urine samples were placed in wells of cell culture plates, increasing concentrations of ammonium hydroxide were added to adjacent wells to stimulate struvite crystal growth, and the plates were incubated at 37 C. The effect of albumin and THP on crystal growth in sample wells was compared with that in control wells, without protein addition, in the same plate. Crystal growth was assessed by determination of number of crystals and supersaturation index, a scale of crystal habit at different degrees of supersaturation, by use of direct visualization with an inverted microscope. Albumin addition did not have significant effect on either crystal number or supersaturation, compared with controls. Addition of THP significantly (P < 0.05) increased crystal number and supersaturation index. It was concluded that THP significantly (P < 0.05) promoted growth of struvite crystals in feline urine, and thus, may have a role in feline struvite uroliths and struvite urethral plug formation.

Uromodulin (Tamm-Horsfall protein) is a leukocyte adhesion molecule

Uromodulin (Tamm-Horsfall protein), the most abundant constituent of human urine, is synthesized exclusively in the kidney tubular epithelium and its amino acid sequence suggests a capacity for cell adhesion. We investigated adhesion between human uromodulin and neutrophils by allowing uromodulin, immobilized on microtiter plates, to interact with neutrophils. It was found that neutrophils attached to uromodulin in a saturable manner. The binding was inhibited by uromodulin in solution. It required metabolically active cells, was calcium sensitive and could be inhibited by arginine-glycine- aspartate-containing peptides in solution. These data suggest that uromodoulin can act as a specific ligand for neutrophils. This interaction is potentially important in leukocyte trafficking in the kidney and in the pathogenesis of interstitial nephritis.

Citrate and calcium effects on Tamm-Horsfall glycoprotein as a modifier of calcium oxalate crystal aggregation

We measured the effects of Tamm-Horsfall glycoprotein (THP) on calcium oxalate monohydrate (COM) crystal aggregation (Ac) in vitro as well as intrinsic viscosities (Vi) of THP at pH 5.7 and 200 mM NaCl and studied the effects of calcium and citrate on these parameters. THP were isolated from 24-h urines of seven male recurrent calcium stone formers (RCSF) and eight age-matched male healthy volunteers (N, normal). At basal conditions, RCSF-THP inhibited Ac by 28 +/- 10% and normal THP by 60 +/- 6% (P = 0.028). In the presence of calcium, increasing THP concentrations from 16 to 28 and 40 mg/l progressively lowered inhibition by RCSF-THP, but not by N-THP. At 40 mg/l, inhibition by N-THP was 27 +/- 9% vs. -43 +/- 8% by RCSF-THP (P = 0.001), i.e., all stone former THP promoted Ac. With an additional 3.5 mM of citrate, inhibition of Ac was 56 +/- 5% by normal and 34 +/- 6% by stone former THP (P = 0.021), and all seven stone former THP again inhibited Ac. Vi of RCSF-THP was higher than that of N at basal conditions (162 +/- 21 vs. 93 +/- 15 ml/g, P = 0.021) and in the presence of 5 mM calcium (352 +/- 54 vs. 118 +/- 17 ml/g, P = 0.001), i.e., RCSF-THP were more self-aggregated, but not when citrate was added (185 +/- 29 vs. 123 +/- 19 ml/g). (ABSTRACT TRUNCATED AT 250 WORDS)

Tamm-Horsfall urinary glycoprotein enhances monokine release and augments lymphocyte proliferation

Tamm-Horsfall glycoprotein (THG) purified from pregnancy urine was found to stimulate normal human mononuclear cell (MNC) proliferation at a concentration greater than 10 micrograms/ml. This stimulation was non-specific because the percentage of B and T cell subpopulations including CD20, CD3, CD4, CD8 and CD4/CD8 ratio was not changed by THG. THG not only bound to human mononuclear cells but depolarized the membrane potential, increased 22Na+ uptake and enhanced the expression of IL-2R and HLA-class II antigens on these cells. The concentrations of sIL-2R, sCD4 and sCD8 in the THG-stimulated MNC culture supernatants were significantly increased compared with control supernatants. In addition, overnight incubation of THG (5-50 micrograms/ml) with MNC dose-responsively enhanced the syntheses of IL-1 beta, IL-6 and TNF-alpha by monocytes, with a maximal effect at 25 micrograms/ml. This monokine releasing activity of THG could be neutralized by a specific antibody against THG. When monocytes/macrophages were depleted from mononuclear cells by incubating with lysosomotropic methyl ester of L-leucine, THG retained the capability of stimulating lymphocytes proliferation but to a lesser degree. These results suggest that urinary THG activates monocytes to synthesize large amount of monokines through its membrane effect. The released monokines subsequently stimulate lymphocytes expressing IL-2R and HLA-class II antigens and finally lead to cell proliferation.

The interaction of Tamm-Horsfall protein with the extracellular matrix

Tamm-Horsfall protein (THP) is the major glycoprotein component of urine, yet its biological role remains obscure. Recent reports have suggested that a concanavalin A (Con A)-binding fraction of THP from pregnancy urine can bind the cytokines tumour necrosis factor-alpha (TNF-alpha) and interleukin-1 (IL-1). In order to investigate this claim in relation to THP from normal adult urine we raised monoclonal antibodies to THP and sought THP/TNF-alpha interactions in three separate assay systems. We found no evidence that THP binds to TNF-alpha under physiological conditions, but we observed that it exerts a weak, probably not physiologically relevant, but reproducible inhibitory effect on the toxicity of TNF-alpha for monolayers of L929 cells, even when the cells are pretreated with the THP, and washed before addition of the cytokine. Since our preparations of THP do not interact directly with TNF-alpha we postulated an interaction with the cells themselves, or with their extracellular matrix. The THP was found by ELISA, immunoblotting and immunohistology, to bind to as yet unidentified components of the extracellular matrix in a manner dependent on cations, pH and carbohydrates. These data, considered in the light of the published amino acid sequence and biochemical properties, suggest that THP is a member of a structural glycoprotein family known to modulate cell adhesion.

Regulation of renal epithelial cell endocytosis of calcium oxalate monohydrate crystals

The earliest events in the formation of kidney stones are unknown. The most common crystal in kidney stones, calcium oxalate monohydrate (COM), when added to cultures of monkey kidney epithelial cells (BSC-1 line), was internalized by 19% of the cells after 30 min. COM crystal endocytosis was enhanced by serum, ADP, and epidermal growth factor, which are potent mitogens for these cells. Endocytosis of COM crystals was inhibited by diverse molecules including Tamm-Horsfall glycoprotein (THP), the tetrapeptide arginine-glycine-aspartic acid-serine, fibronectin, transforming growth factor-beta 2, and heparin. The capacity of THP, fibronectin, or heparin to inhibit endocytosis was mediated by an interaction of these molecules with cells, not by coating the crystals. Thus renal epithelial cell endocytosis of COM crystals can be regulated by diverse molecules including THP, the most common protein found in human urine. Crystal endocytosis and subsequent cellular responses could be important pathogenic steps in nephrolithiasis.

Release of gelatinase and superoxide from human mononuclear phagocytes in response to particulate Tamm Horsfall protein

This study describes the in vitro activation of human mononuclear phagocytes by particulate Tamm Horsfall protein (THP). Peripheral blood monocytes phagocytosed THP particles with the accompanying release of superoxide radicals, N-acetyl-beta-D-glucosaminidase, and neutral metalloproteinase. Immunoprecipitation and substrate gel analysis identified the neutral proteinase as a 95-kd gelatinase. A comparison with other particulate ligands highlighted the specificity of the response to THP and showed that the magnitude of the response was comparable with that obtained with lipopolysaccharide (100 micrograms/ml). Parallel studies using peritoneal macrophages resulted in a similar pattern of enzyme release and reactive oxygen species synthesis. THP has been implicated in the pathogenesis of tubulointerstitial nephritis associated with reflux nephropathy. The present study indicates that an inflammatory response initiated by a neutrophil-THP interaction may be extended into a chronic phase via the activation of mononuclear phagocytes. The subsequent release of reactive oxygen metabolites and proteinases may contribute to the tissue damage and fibrosis associated with chronic immune-mediated tubulointerstitial nephritis.

Tamm-Horsfall glycoprotein (THG) purified from normal human pregnancy urine increases phagocytosis, complement receptor expressions and arachidonic acid metabolism of polymorphonuclear neutrophils

Tamm-Horsfall glycoprotein (THG) purified from normal human pregnancy urine was found to increase polymorphonuclear neutrophil (PMN) phagocytosis (46.57 +/- 3.54% in the medium versus 75.85 +/- 5.37% in the presence of 25 micrograms/ml THG) after 30 min preincubation. The phagocytosis-enhancing activity of THG was dose-dependent (5-50 micrograms/ml) and was possibly mediated by the increased expressions of complement receptor type 1 (CR1) and type 3 (CR3) on the neutrophils. The release of [3H]arachidonic acid and prostaglandin E2 (PGE2), but not thromboxane B2 (TXB2), from neutrophils were also significantly enhanced by THG. Using 3,3'-dihexyloxacarbocyanine iodide as indicator, THG (25 micrograms/ml) depolarized the membrane potential of PMN after 30 min preincubation. In addition, THG exhibited a specific membranotropic effect with PMN. It is conceivable that THG binds to the cell surface and depolarizes the membrane potential of PMN which subsequently enhances the release of arachidonic acid metabolites and the translocation of the complement receptors to the membrane. These biochemical events lead to the increment of PMN phagocytosis and suggests that THG may play an important role in the defense mechanisms of the urinary tract in that a large amount of THG is usually present.

Human blood monocyte activation by Nocardia rubra cell wall skeleton for productions of interleukin 1 and tumor necrosis factor-alpha

Human blood monocytes were obtained from peripheral blood of healthy donors by counter-flow centrifugal elutriation. Functional integrity of monocytes for production of interleukin 1 (IL-1) and tumor necrosis factor alpha (TNF-alpha) in response to Nocardia rubra cell wall skeleton (N-CWS) was examined by bioassay and enzyme immunoassay. Monocytes treated with N-CWS at more than 0.5 microgram/ml produced IL-1 and TNF-alpha extracellularly. Extracellular TNF activity appeared within 4 h, and maximally, 16 h after N-CWS stimulation, whereas longer time was needed for IL-1 activity to appear, the peak production being at 24 h. The neutralizing experiment also showed that anti TNF-alpha antibody did not affect IL-1 production by the monocytes treated with N-CWS, suggesting independency of IL-1 production of TNF-alpha. These results suggest that the therapeutic antitumor effect of N-CWS is due, in part at least, to the augmented production of these monokines.

Investigations on macromolecular precipitation inhibitors of calcium oxalate

Certain important aspects of the urine oxalate tolerance test (OTT) have been revised. The stirring system has been changed and the test has been adapted to the kinetics of calcium oxalate precipitation. True equilibrium conditions are now ensured during the measurements. Furthermore, the endogenous oxalate concentration is determined and taken into consideration. As a result of these changes, the significance of the test results has greatly improved. The effects of the addition of small amounts of zinc on the precipitation of calcium oxalate have been used in a new variation of the OTT. This new test makes it possible to discriminate much faster and more simply between recurrent stone-formers and other subjects. Tamm-Horsfall protein (THP) has been tested for its effect on the precipitation of calcium oxalate by means of OTT. THP inhibits the precipitation of calcium oxalate, but THP of stone-formers has a diminished inhibitory activity. The inhibitory activity of this protein strongly depends on the method by which it is isolated.

Effect of Tamm-Horsfall protein on chemoluminescence response of polymorphonuclear leukocytes to uropathogenic Escherichia coli

Mannose residues on the outer membranes of polymorphonuclear leukocytes (PMNL) are capable of binding mannose-sensitive Escherichia coli. Tamm-Horsfall protein, a major urinary glycoprotein, has also been shown to bind mannose-sensitive E. coli via mannose-containing side chains. The effect of Tamm-Horsfall protein on the interaction between PMNL and mannose-sensitive E. coli was studied by measuring luminol-dependent chemoluminescence after bacterial stimulation. In the presence of 0.475, 4.75, 47.5, and 475 mg/l Tamm-Horsfall protein, chemoluminescence responses were reduced in a dose-dependent fashion by 8.7%, 38.1%, 60.3%, and 96.1%, respectively. Addition of 0.003 units/ml alpha-mannosidase reversed the effect of increasing concentrations significantly. Thus, urinary Tamm-Horsfall protein seems to compete with PMNL for mannose-sensitive E. coli in a mannose-sensitive fashion, thereby significantly reducing the role of PMNL as a defense mechanism in the urine of patients with urinary tract infection.

Effects of chondroitin sulphate, human serum albumin and Tamm-Horsfall mucoprotein on calcium oxalate crystallization in undiluted human urine

The effects of physiological concentrations of chondroitin sulphate, human serum albumin and Tamm-Horsfall mucoprotein on the crystallization of calcium oxalate in undiluted, ultrafiltered human urine were investigated using particle size analysis and scanning electron microscopy. Neither the amount of oxalate required to induce detectable calcium oxalate crystal nucleation nor crystal morphology was affected by the presence of any of these macromolecules. Chondroitin sulphate had no effect on the amount of crystalline material deposited or on the size of the particles precipitated in response to a standard oxalate load. Human serum albumin slightly reduced the size of the crystal aggregates and caused a small increase in the amount of crystal matter precipitated. By contrast, Tamm-Horsfall mucoprotein significantly inhibited crystal aggregation and markedly increased the volume of matter deposited, although this could not be attributed to a promotion of solute precipitation. It was concluded that chondroitin sulphate, human serum albumin and Tamm-Horsfall mucoprotein cannot account for the inhibitory effects of macromolecules with a relative mass greater than 10 kDa in spun and filtered urine. Nonetheless, Tamm-Horsfall mucoprotein is likely to inhibit crystal aggregation in whole urine in vivo and may therefore be instrumental in preventing calcium oxalate stone formation.

Molecular abnormality of Tamm-Horsfall glycoprotein in calcium oxalate nephrolithiasis

Tamm-Horsfall glycoprotein (THP) inhibits self-aggregation of calcium oxalate monohydrate (COM) crystals and may therefore be part of the natural defenses against deposition of COM in the kidney in the form of stones or nephrocalcinosis. We have studied THP from six patients with severe nephrolithiasis and have found that their THP inhibits COM self-aggregation less than normal THP under conditions of NaCl and THP concentration and pH similar to those of human urine. The reason for the reduced inhibition of COM crystal aggregation seems to be an enhanced self-aggregation of patient THP, which removes it from effective interactions with the COM crystals. In one family, the father and the oldest son both excreted THP that behaved abnormally and in similar ways, whereas THP from the other son and from the wife behaved normally.

Evidence that specific high-mannose oligosaccharides can directly inhibit antigen-driven T-cell responses

Uromodulin is an 85 Kd immunosuppressive glycoprotein originally isolated from human pregnancy urine. It is unique in that most of its biologic activity can be attributed to attached oligosaccharides. Purified immunomodulatory oligosaccharides from uromodulin have been structurally characterized using 1H-NMR spectroscopy and shown to be Man6-7GlcNAc2(M6,M7). Based on these observations, we isolated high-mannose N-type oligosaccharides and glycopeptides from ovalbumin, soybean agglutinin, and yeast mannan and show that these high-mannose compounds directly inhibit in vitro antigen-driven T-cell proliferation from millimolar to nanomolar concentrations. The most active compound was a core mannose oligosaccharide derived from yeast mannan, M9(y), which acts to block early events required for normal antigen processing/presentation. These data emphasize the potential functional role of carbohydrate structure in regulating the human immune response.