Further evidence for the mitogenic action of urinary trypsin inhibitor

We have previously shown that urinary trypsin inhibitor (UTI), also known and bikunin, was mitogenic for human fibroblasts at low concentrations, and growth-inhibitory at higher concentrations, and have identified high- and low-affinity cellular binding sites for this protein. We have now investigated fibroblast proteins which interact with bikunin. Bikunin binds to proteins of about 50K and 250K. The simplest interpretation, is that the 50K protein may be a proteinase which is also the low-affinity bikunin binding site, involved in growth inhibition, and that the larger protein may be responsible for the mitogenic response to bikunin. Inhibitors of intracellular calcium mobilisation also inhibit the mitogenic response to bikunin, and by the measurement of the efflux of pre-loaded 45Ca2+, bikunin at mitogenic concentrations can be shown to stimulate calcium mobilization.

Identification of uronic-acid-rich protein as urinary bikunin, the light chain of inter-alpha-inhibitor

Uronic-acid-rich protein (UAP) is a urinary glycoprotein that inhibits calcium oxalate crystallization in vitro. It shows a structural similarity to bikunin, a component of inter-alpha-inhibitor (IalphaI) known for its inhibition of the action of many serine proteinases like trypsin and chymotrypsin. To clarify the relationship between these macromolecules, UAP, IalphaI, urinary bikunin, and plasma bikunin were purified and studied. Their calcium oxalate crystallization inhibitory activity was assayed before and after treatment with chondroitinase AC and pronase. Their molecular mass was determined by using SDS/PAGE before and after these treatments. Polyclonal bikunin antibody was used on Western blots for immunological identification. The partial amino acid sequence of UAP before and after chondroitinase treatment was determined. Also, the antitryptic activity of UAP was measured and compared to that of bikunin, which is responsible for the antiprotease activity of IalphaI. UAP exhibited a strong calcium oxalate crystallization inhibitory activity. IalphaI and both bikunins were less inhibitory. Chondroitinase AC had no effect on inhibitory activity of these proteins even when their molecular mass changed. However, after pronase treatment, the inhibitory activity of both bikunins and UAP was completely destroyed. The antitryptic activity of UAP was found to be 0.78 U/mg which is lower than that of bikunin which is about 1.9 U/mg. On Western blotting, bikunin antibody immunoreacted with UAP and both urinary and plasma bikunins. Partial amino acid sequence confirmed the identity of UAP as urinary bikunin.

Increased urinary trypsin-inhibitory activity in mercuric chloride induced nephrotoxicity in Wistar rats

The relationship between trypsin-inhibitory activity (TIA) and the nephrotoxic effects of mercuric chloride (HgCl2)--as illustrated by proteinuria and by a drop in the glomerular filtration rate (GFR) measured by creatinine clearance test (CCT)--was investigated in Wistar rats. HgCl2, 150 or 250 micrograms/100 g BW per day was injected intraperitoneally three times a week for 2 weeks. Both groups showed a significant degree of proteinuria and urinary TIA. Group B (250 micrograms HgCl2/100 g BW) displayed a greater drop in GFR than group A (150 micrograms HgCl2/100 g BW). The urinary TIA was significantly correlated with proteinuria (group A: r = 0.87, group B: r = 0.84), but it was also significantly inversely correlated with the CCT (A: r = -0.96; B: r = -0.88).

IN CONCLUSION

these results suggest that increased urinary TIA may be involved in and indicative of the pathogenesis of mercuric chloride induced nephrotoxicity.

[Postoperative urinary ulinastatin secretion and renal function in hepatectomized patients with and without liver cirrhosis]

We compared ulinastatin secretion into urine with renal function during postoperative period in three groups, hepatectomized group with liver cirrhosis (LC(+), n = 7), hepatectomized group without liver cirrhosis (LC(-), n = 4) and subtotal gastrectomized group with normal liver function (GR, n = 7). In LC(+) group, N-acetyl-beta-D-glucosaminidase (NAG) increased above normal upper limit throughout the postoperative period. Ulinastatin (UTI) also increased but the increase was not remarkable. In LC(-) group, NAG increase but not significantly compared with the preoperative value. UTI increased from 5.8 +/- 3.0 IU.mg x Cr-1 to 30.8 +/- 16.6 IU.mg x Cr-1 and 39.9 +/- 9.0 IU. mg x Cr-1 on the 1st and 3rd postoperative day respectively. In GR group, there was no change in NAG value. UTI on the 3rd postoperative day increased significantly (from 10.0 +/- 7.7 to 75.4 +/- 39.0 IU.mg x Cr-1). A small urinary secretion of UTI and increased NAG during postoperative period in LC(+) group suggest that UTI might play an important role in postoperative renal dysfunction in patients with liver cirrhosis.

Urinary trypsin inhibitor may have a protective effect on endothelial cells in preeclampsia

Urinary trypsin inhibitor is a glycoprotein which has an inhibitory effect on many enzymes, especially neutrophil elastase. The concentration of urinary trypsin inhibitor in serum (maternal and fetal), urine and amniotic fluid was measured in 20 cases of preeclampsia and compared with levels in normal pregnancy. Urinary trypsin inhibitor levels were significantly increased in the maternal and fetal serum of preeclamptic patients compared to normal pregnancy (p < 0.0001), as well as in urine and amniotic fluid of the same patients. Relative fluorescence release of a calcium chelating agent (fura-2) from human umbilical vein endothelial cell cultures was significantly increased by preeclamptic serum compared to serum of normal pregnant women (p < 0.03). After incubation of urinary trypsin inhibitor with the cultures, significant decrease of fura-2 release was observed (p < 0.03). Urinary trypsin inhibitor has an effect on suppression of activated neutrophils, elastase production and may have a protective effect on endothelial cells.

Charge isomers of urinary bikunin (trypsin inhibitor)

It was observed that the purified urinary bikunin (trypsin inhibitor) consisted of four major isomers with different electric charges which could be separated by HPLC using a Mono Q column. These isomers revealed the same antitrypsin activity and did not show any differences in the apparent molecular weight by SDS-PAGE, amino-acid composition, N-terminal amino-acid sequence (1-40) and C-terminal amino acid (Leu). The contents of sialic acid and uronic acid were also identical among these isomers. However, analysis of chondroitin sulfate revealed all the glycosaminoglycan chains of these isomers were undersulfated, comprising nonsulfated and 4-sulfated disaccharide units, and 4-sulfated disaccharide unit ratio varied among these isomers. After the chondroitin ABC lyase digestion, all the isomers were eluted at the same position on a Mono Q column chromatography. These results indicated that charge isomers of urinary bikunin was attributed to the difference on sulfation ratio in a glycosaminoglycan chain.

[Value of the assay of protein SAA and urinary antitrypsin activity in osteoarticular infections]

Erythrocyte sedimentation rate is normal in 20% to 25% of patients with discitis due to common pathogens. We evaluated serum amyloid A (SAA) protein and urinary trypsin inhibitory activity in osteoarticular infections comparatively with erythrocyte sedimentation rate and serum C-reactive protein in 20 patients including 14 with discitis due to common pathogens and 6 with septic arthritis. Assays were performed on D0, D8, D15, D30, and D60 after initiation of antimicrobial therapy. On D0, all four markers were significantly higher in patients with septic arthritis than in patients with discitis. C-reactive protein levels exhibited the fastest kinetics with a return to normal values within 15 days in both conditions. Urinary trypsin inhibitory activity was only slightly elevated in patients with discitis and returned to normal within 30 days in both conditions. Serum amyloid A levels required 30 to 60 days to return to normal. Erythrocyte sedimentation rate exhibited the slowest kinetics, with normal values being achieved only after 60 days. Although simple, rapid, and inexpensive, urinary trypsin inhibitory activity determination exhibits poor sensitivity. Serum amyloid A assay is not routinely available but may be a valuable parameter for monitoring patients whose erythrocyte sedimentation rate and C-reactive protein level are normal (as in 2 of our patients with discitis).

Structural analysis of a low-sulfated chondroitin sulfate chain in human urinary trypsin inhibitor

The low-sulfated chondroitin 4-sulfate(LSC) chain from human urinary trypsin inhibitor was purified and the structure was characterized. After hyaluronidase SD digestion of LSC, an oligosaccharide which contains the linkage region could be obtained. The structure of oligosaccharide was analyzed by HPLC and 500 MHz 1H-NMR spectroscopy. The analytical results revealed that 4-O-sulfo GalNAc residues were located in the neighborhood of the linkage region.

[A new method of isolating acid-stable trypsin inhibitor from human urine]

A novel procedure for isolation of an acid-resistant trypsin inhibitor from human urine (UTI) is described. The method is based on the use of immobilized on an insoluble matrix monoclonal antibodies specific for the given inhibitor. The use of Immotin (which represents an immobilized on Sepharose 4B UTI) as precolumn during affinity chromatography makes it possible to significantly prolong the immunoadsorbent life and to increase the inhibitor yield up to 92% of its original content in the urine. The preparation obtained with the use of an immunoadsorbent contains predominantly the native form of the inhibitor whose molecular mass is about 44 kDa.

Assessment of the clinical value of urinary trypsin inhibitory activity in elderly people

To assess the clinical value of urinary trypsin inhibitory activity (UTIA) in elderly people, a prospective study was carried out over 4 months in our internal medicine department. Two hundred and forty-three patients of more than 60 years of age were included. A positive correlation was observed between UTIA and serum creatinine (p < 10(-3)). In the population with serum creatinine of less than 133 mumol/l (200 patients), UTIA was independent of age, sex and serum creatinine. UTIA was compared with seven serum inflammatory proteins titrated on patient admission. The principal interest of UTIA determination appeared in bacterial infections. UTIA was significantly increased in this group (p < 10(-4)). However, a positive correlation was proved only with C-reactive protein (CRP) (p = 9 x 10(-4)). Nevertheless, CRP appeared to be the best marker of bacterial infectious diseases after receiver operating characteristic curves analysis.

Structural analysis of the N-linked oligosaccharides from human urinary trypsin inhibitor

The N-linked oligosaccharides from human urinary trypsin inhibitor were purified and their structures were investigated by compositional analysis, the two-dimensional sugar map method and 500 MHz 1H-NMR. The results revealed that they were composed of disialosyl, monosialosyl and asialosyl oligosaccharides, which have the common biantennary core structure; Gal1-4GlcNAc1-2Man1-3(Gal1-4GlcNAc1-2Man1-6)M an1-4GlcNAc1-4GlcNAc.

Existence of a human urinary trypsin inhibitor (urinastatin)-like substance in the rat brain

A human urinary trypsin inhibitor, urinastatin (UT)-like immunoreactive substance with trypsin inhibitory activity, was demonstrated in certain brain regions in rats, especially the cerebral cortex, hippocampus and hypothalamus. Although this UT-like substance in the rat brain displayed an N-terminal amino acid sequence similar to that of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), it did not show any GAPDH activity. These results indicate that the UT-like substance in the rat brain is a protein different from GAPDH and indicates a localized distribution within certain brain regions partly related to learning and memory.

Urinary trypsin inhibitory activity for the diagnosis of bacterial infection: a prospective study in 690 patients

OBJECTIVES

During the acute phase response, interleukin-1 induces production of inter-alpha-trypsin inhibitor. The measurement of urinary trypsin inhibitory activity which results from the effects of inter-alpha-trypsin inhibitor degradation products is easy, quick and inexpensive. We conducted a prospective study to investigate its value as a diagnostic tool in comparison with C-reactive protein.

METHODS

Comparisons were made in 690 consecutive patients at admission to a department of internal medicine.

RESULTS

The level of urinary trypsin inhibitory activity was significantly higher in patients with bacterial infection (mean = 123 IU/g creatinine) than in patients with either viral infection (34 IU), cancer (50 IU), elevated erythrocyte sedimentation rate without infection (45 IU), miscellaneous non-inflammatory diseases (27 IU) or in non-organic controls (19 IU) (Dunnet's test, p << 0.01). The receiver operating characteristic curve showed that sensitivity and specificity of urinary trypsin inhibitory activity were higher than those of C-Reactive protein for the diagnosis of bacterial infection. For levels > or = 60 IU, sensitivity was 75% and specificity 89%. Urinary trypsin inhibitory activity levels fell within 2 days in patients treated for acute bacterial infection.

CONCLUSION

Urinary trypsin inhibitory activity could be a useful marker of bacterial infection particularly in patients with fever of unknown origin and/or elevated erythrocyte sedimentation rate.

[Urinary trypsin inhibitor as an acute phase reactant]

Early in this century, trypsin inhibiting activity has already been recognized in patients with acute infection or renal disease. In addition to these, conditions such as coronary thrombosis, surgical operation, artificial fever by heat-killed bacilli, malignancy, leukemia, later stage of normal pregnancy, etc. have been known to cause the elevated excretion of UTI in urine. Typically, maximal excretion of UTI has been observed within one or two days after the onset. It appears that recent studies have overcome the complexity of UTI molecule. Automated measurement of urinary trypsin inhibitor (UTI) in urine sample was carried out by either enzymic or immunologic method. UTI as well as erythrocyte sedimentation rate and C-reactive protein enables us to monitor acute phase response, being confirmed in cases of abdominal surgery.

Biosynthesis of bikunin (urinary trypsin inhibitor) in rat hepatocytes

One of the major sulfated proteins secreted by rat hepatocytes contains a low-sulfated chondroitin sulfate chain and its apparent molecular mass upon sodium dodecyl sulfate/polyacrylamide gel electrophoresis shifts from 40 to 28 kDa upon chondroitinase ABC treatment (E. M. Sjöberg and E. Fries, 1990, Biochem. J. 272, 113-118). These properties suggest that this protein is the rat homologue of the major trypsin inhibitor of human urine which was recently named bikunin. In serum, bikunin occurs mainly as a subunit of the pre-alpha-inhibitor and the inter-alpha-inhibitor; in these proteins it is covalently linked to the other polypeptides through its chondroitin sulfate chain. Bikunin has been shown to be synthesized by liver cells as a 42-kDa precursor, in which it is linked to alpha 1-microglobulin by two basic amino acids. We have isolated bikunin from rat urine and prepared antibodies against it. In rat hepatocytes pulse-labeled with [35S]methionine, these antibodies precipitated a labeled protein of 42 kDa. Upon chase, three different labeled proteins were recognized by the antibodies in the medium: one protein of 40 kDa (free bikunin), one of 125 kDa (presumably pre-alpha-inhibitor), and one greater than 240 kDa (possibly a protein related to the inter-alpha-inhibitor). Pulse-chase experiments with [35S]sulfate showed that these proteins occurred intracellularly as precursors containing alpha 1-microglobulin. These results demonstrate that the completion of the chondroitin sulfate chain and its coupling to other polypeptide chains occur before the cleavage of the alpha 1-microglobulin/bikunin precursor.

Study on proteoglycans having low-sulfated chondroitin 4-sulfate in human urine and serum

State analysis of low-sulfated chondroitin 4-sulfate (LSC) in human urine and serum was performed by the use of high performance liquid chromatography and Western blot analysis. It was revealed that the most amount of LSC in urine is present as urinary trypsin inhibitor and a small amount (about 10% of total LSC) is as an LSC chain. The LSC in serum is mainly present as a proteoglycan such as inter-alpha-trypsin inhibitor (ITI), with a molecular weight of 212 kDa, but a small amount of LSC-proteoglycans having molecular weights of 128 and 38 kDa were also observed on SDS-PAGE. Those two compounds may be fragments of ITI, or one of the compounds (128 kDa) may be pre-alpha-trypsin inhibitor which was found by Enghild et al. (J. Biol. Chem., 264, 15975 (1989)).

Characterization of a trypsin inhibitor from equine urine

A trypsin inhibitor was isolated from pregnant mares' urine by adsorption on bentonite and elution with aqueous pyridine followed by batch DEAE-cellulose treatment and column chromatography. Final purification to an electrophoretically homogenous glycoprotein was achieved by gel permeation chromatography. This equine urinary trypsin inhibitor (E-UTI) is acid- and heat-stable, has a molecular weight of 22 to 23 kDa, an isoelectric point of 4.55, forms a 1:1 molar complex with trypsin and has serine as its N-terminal amino acid. The N-terminal amino acid sequence of this protein is almost identical with that of EI-14, the inhibitor obtained from horse serum by tryptic treatment, except for two extra amino acid residues, Ser-Lys- on the N-terminal end of E-UTI. In its isoelectric point E-UTI differs from EI-14 and the inhibitor from human urine.

Distribution and elimination of intravenously injected urinary trypsin inhibitor

Elimination of human urinary trypsin inhibitor (UTI) after intravenous injection of 125I-labelled UTI was followed by serial plasma and urine samples in three male volunteers. The plasma half-life of 125IUTI during 0-3 h after injection was 33 min and during the following 4 hours the half-life was 2 hours. Free, biologically active inhibitor was found in the urine during the first four hours after injection. Most of the radioactivity in the urine, however, corresponded to free 125I probably released during the degradation of UTI in the kidney. The distribution of UTI was studied after injection of 125IUTI in rats by measurement of radioactivity in excised organs. Fifteen min after the injection 44% of the radioactivity was found in the kidneys and 9% in the liver, implying that the kidneys are the primary site of UTI metabolism.

Establishment of an enzyme-linked immuno-sorbent assay for urinary trypsin inhibitor by using a monoclonal antibody

Monoclonal antibodies against inter-alpha-trypsin-inhibitor (ITI) were produced. One clone showing specificity for urinary trypsin inhibitor (UTI), a proteolytic fragment of ITI, which is excreted into urine, was selected for the establishment of an enzyme-linked immuno-sorbent assay (ELISA). The ELISA for the quantification of UTI was shown to work reproducibly in the range between 0.5 and 10 ng UTI/ml urine. Urines of several patients suffering from different lung diseases were screened for UTI using the established ELISA. Highest UTI levels were found in the urine of patients with lung empyema. A more moderate increase was observed in patients suffering from lung tuberculosis and from secondary and primary lung tumors.

Significance of microbiological and biochemical analyses in empyema thoracis

Following the indifferent results of a retrospective analysis, a prospective study was undertaken to analyse the causative organisms in 51 cases of empyema. Cultures were positive in 44/51 (= 86.3%) cases. 2 bacterial species were recovered for each empyema. The aerobic gram-positive cocci represented the largest group (57%), followed by aerobic gram-negative bacteria (18.6%), anaerobic bacteria (18.6%), and fungi (5.8%). Polymicrobial empyema accounted for 59.1% of the cases. Anaerobic bacteria were cultured from 36.4% of empyema. Anaerobic bacteria were more frequently isolated from pleural effusions than from other specimens. Swabs were found to be of minor value for anaerobics. Analyses of glucose and pH value in pleural effusions have been reported to be useful in differentiating complicated from uncomplicated effusions in cases where the aspirated fluid is not purulent and is negative on gram stain, but clinical as well as radiological findings point to an empyema. Our results have shown that pH-values less than 7.30 and Glucose less than 60 mg/dl were not absolutely specific for empyema. In contrast, PMN-elastase in pleural effusion and HI-30 in urine showed a statistically significant differentiation of empyema from exudates of other origin.

[Development of an immunoenzyme method for the quantitative determination of an acid-stable trypsin inhibitor in urine: use for assessing the severity of glomerulonephritis]

Acid-stable trypsin inhibitor was isolated from urine of healthy persons; its homogeneous preparation was obtained using absorption on chitosan, affinity chromatography on chymotrypsin-Sepharose 4B and gel filtration of Sephadex G-100. Two forms of the inhibitor were produced with Mr = 44,000 and 22,000; yield of the trypsin inhibitor was about 70% of its content in urine. Indirect immunoenzymatic assay was developed for the inhibitor estimation; optimal conditions were chosen for sorption of the inhibitor on polystyrene plates as well as for dilution of rabbit anti-inhibitor blood serum and of goat antibodies to rabbit antibodies and horse radish peroxidase conjugates. The procedure developed was sensitive; 10-20 ng of the inhibitor was detected per a sample. Urine of healthy persons and of patients with latent and nephrotic forms of glomerulonephritis was studied using the test system developed. The results of estimation of the trypsin inhibitor were considered in diagnostics and evaluation of severity of glomerulonephritis.

Human urinary trypsin inhibitor (urinastatin)-like substance in mouse kidney and its relationships to mouse kidney kallikrein

Mouse kidney contains urinastatin (UT)-like immunoreactive substances with trypsin inhibitory activity. Immunohistochemical studies show that these UT-like substances are localized in the same region as kidney kallikrein, i.e. in the distal tubules. Sephadex column chromatography of mouse kidney extract using 0.1M NaCl as the eluent yielded fractions (C.F.) containing both UT-like and kallikrein-like material. In these fractions (C.F.), the removal of UT-like material caused a concomitant decrease in kallikrein-like activity and vice versa. However, when the kidney extract was eluted with an acidic buffer of high ionic strength, the fractions containing both UT-like and kallikrein-like substances were not observed. These results suggest that these two components are intimately bound to one another. The kallikrein activity responded differently to pH, to metal ions (zinc and copper), and to the sodium/potassium ratio, depending on the concomitant presence or absence of UT-like material. These findings suggest that kallikrein activity in kidney tissue is modified by the presence of an UT-like substance.