Identification of a type V collagen-degrading enzyme from human sputum

An enzyme capable of degrading type V collagen was found in the sputum of patients with chronic obstructive pulmonary disease (COPD). This enzyme was found in a latent form and was activated by 4-aminophenylmercuric acetate (APMA). Molecular sieve chromatography on Ultrogel AcA-34 and affinity chromatography on type V collagen-Sepharose were successful in separating type V from type I collagenolytic activity. The enzyme became active after affinity chromatography and no longer required activation with APMA to manifest activity. It was found to be a metalloproteinase by virtue of its inhibition by ethylene-diaminetetraacetic acid and phenanthroline but not by phenylmethanesulfonyl fluoride or N-ethylmaleimide. Because degradation of matrix proteins is felt to be important in the pathogenesis of COPD, it is possible that the selective degradation of type V collagen by this enzyme may play a role in the development of COPD.

Alterations in collagen production in mixed mononuclear leukocyte-fibroblast cultures

The cell-cell interactions between fibroblasts and mononuclear leukocytes (MNL) which promote alterations in collagen accumulation were examined using a system of co-culture of human fibroblasts and peripheral blood MNL. The stimulation of collagen production was optimal after 48 h of co-culture and the increase in collagen correlated directly with the number of MNL added. The enhancement of collagen production was seen in both autologous and allogeneic co- cultures. Stimulation of non-collagenous protein was also noted. Co- culture supernatants contained soluble substances that were capable of stimulating collagen production, although they stimulated collagen production to a lesser degree than direct co-culture. Fractionation of these supernatants on Sephadex G-200 revealed a predominant area of stimulatory activity at 160,000 mol wt. Lesser areas of activity were noted at molecular weights of 80,000 and 25,000. Determination of the types of collagen produced by fibroblasts during co-culture with MNL showed that the ratio of type I:III collagen was decreased. These alterations in both the quantitative and qualitative accumulation of collagen mimic the changes often seen in wound healing and early inflammation suggesting that cellular interactions between fibroblasts and MNL may be important in the modulation of collagen production in normal and pathologic states.

Separation of myelin basic protein peptide 43-88 and its fragments by analytic and preparative high-performance liquid chromatography

Reversed-phase (RP) high-performance liquid chromatography (HPLC) using a solvent mixture of triethylammonium formate buffer and methanol permitted the rapid separation of myelin basic protein peptide 43-88 and a mixture of synthetic fragments from this peptide. The elution times for some of the peptides were markedly affected by minimal changes in the solvent mixture. Attempts to separate the same peptides by gel permeation HPLC resulted in poor resolution and an aberrant elution pattern unrelated to molecular size. With the use of the volatile triethylammonium formate buffer in the RP-HPLC, material could be more readily separated and easily recovered by freeze-drying. Analysis of the components separated by this system of RP-HPLC demonstrated that the preparation of normal human BP peptide 43-88 results in an admixture of peptides 43-87 and 43-88. This procedure of RP-HPLC should make it possible to analyze the degradation of myelin basic protein peptide 43-88 and to isolate the degradation products for characterization.

Effect of long-term ethanol feeding on rat liver interstitial collagens

Long-term administration of ethanol to rats over a 12-month period was used in an attempt to compare the altered collagen metabolism in liver damaged rats with that in humans having alcoholic liver disease. The percent collagen in the rat liver increased nearly twofold during this period, but no increase in the rate of collagen biosynthesis was dectected by using pulse, radiolabel proline incorporation into hydroxyproline. Fibrosis was not detectable by histological methods nor were any alterations found in the relative proportions of the genetically distinct type I and type III interstitial collagens. These results demonstrates a minimal yet positive effect of long-term ethanol consumption in rats, with simultaneous increases in both type I and type III hepatic collagens.

Isolation and characterization of a fibrogenic factor from CCl(4)-damaged rat liver

A fibrogenic factor which stimulates collagen production without cell proliferation of rat skin fibroblast cultures was isolated from CCl4-damaged rat liver. (1) The factor was isolated from saline extracts of CCl4-induced fibrotic rat liver and fractionated by Sephadex G-50S gel filtration and DEAE-cellulose chromatography. The original extract produced a 6-fold increase in collagen synthesis and the active factor eluted from gel filtration columns in a region corresponding to 5000 daltons. (2) The active factor was destroyed by heat (57 degrees C, 30 min), phospholipase C digestion, but was insensitive to proteolytic enzymes or phospholipase A. Chemical analysis of the partially purified factor revealed relatively high quantities of phosphorus (3%) and low quantities of protein (13.3%), neutral sugar (1.9%) and uronic acid (4.9%). The possibility of this component being a complex phospholipid containing polypeptide is suggested. (3) Fibrogenic properties of the isolated factor was enhanced by apparent oxidation in air, to a more active, yet insoluble complex. Attempts to solubilize the oxidized product completely destroyed its biological activity.

Procollagen production by rat hepatocytes in primary culture

Hepatocytes were obtained from rat liver and maintained in primary culture for periods up to 14 days. Collagen synthesis was maximal after 3-5 days and declined thereafter. The rate of collagen production was approx. one-tenth that observed by rat skin fibroblasts of the same animals after 3-5 passages. Type I procollagen, the major macromolecular collagenous species, was identified as a 450 000 dalton molecule which was converted to 120 000 dalton, denatured, reduced procollagen chains. Prior pepsin digestion of the native procollagen released 95 000 dalton collagen chains identified as alpha 1(I) and alpha2(I) by co-migration with carrier rat skin type I collagen chains. The production of type III procollagen was also tentatively identified by DEAE-cellulose chromatography. This material was isolated and identified with type-specific antibodies developed against the amino-terminal extension peptide of bovine skin type III procollagen. The relative distribution of type I:type III procollagen was estimated at 7:3 similar to the ratio previously found in whole rat liver. No evidence of type IV or type V procollagen biosynthesis was observed. These results suggest that rat hepatocytes in primary culture are capable of interstitial type I and type III collagen biosynthesis in a ratio similar to that found in their parent hepatic tissue in situ. They also suggest that the less abundant type IV (basement membrane-associated) or type V are not major collagenous products of these cells.

Biochemical and immunochemical characterization and internal alignment of pepsin-derived collagenous fragments of the alpha 1(IV) chain from bovine kidney cortices

This communication describes the immunochemical and biochemical characterization of three polypeptide chains, alpha 1(IV)130K, alpha 1(IV)110K, and alpha 1(IV)75K belonging to the alpha 1(IV) chain of basement membrane collagen isolated from a pepsin digest of bovine kidney cortices. From the CNBr digests of the mixture of these chain fragments three peptides, a major and two minor peptides with an apparent Mr = 32,000, 24,000 and 13,000, respectively, were purified and characterized. The data presented show that CNBr peptides 24K and 13K are generated from CNBr peptide 32K by pepsin cleavage in the native molecule at the NH2-terminal end. Antisera were raised in rabbits against peptide CB32K. Inhibition assays using enzyme-linked immunoadsorbant assays (ELISA) showed cross-reactivity with alpha 1(IV)130K, alpha 1(IV)110K and alpha 1(IV)75K fragments. Peptides CB24K and 13K also inhibited the antiserum. Antiserum was not active when tested against alpha 1(IV)95K, alpha 1(IV)55K, alpha 2(IV)120K, and alpha 2(IV)95K fragments as inhibitors. These studies provide further evidence that alpha 1(IV)130K, 110K, and 75K are derived from the same parent chain. The pepsin cleavage sites resulting in the formation of these fragments and their internal alignment are described.

Type IV collagens' isolation and characterization of 7S collagen from human kidney, liver and lung

7S collagens were isolated after bacterial collagenase treatment of basement membrane material prepared from the pepsin digest of human kidney, liver and lung. The 7S collagens were purified by combination of molecular sieve and ion exchange chromatography. 7S collagen from each of these sources showed similar amino acid composition, electrophoretic patterns of reduced and unreduced samples. Antibodies raised against human placental 7S collagen in rabbits completely cross-reacted with the 7S collagen preparation obtained from kidney, liver and lung in enzyme-immunoassays. Since 7S collagen in known to be a major cross-linked segment of type IV collagens, the data indicate that collagenous proteins of basement membranes are organized in similar networks in a variety of organs.

The influence of pH on the degradation of bovine myelin basic protein by bovine brain cathepsin

The degradation of bovine myelin basic protein by bovine brain cathepsin D (ED 3.4.23.5) was studied over a pH range of 2.75 - 6.0. Throughout this pH range pepstatin, an inhibitor of cathepsin D, prevented the degradation. The degradation at a pH away from the optimum of pH 3.5 was predictably slower, but also resulted in more restricted cleavage. Above pH 4.5 bovine basic protein peptide 1 - 42 was not degraded further to peptide 1 - 36 as occurs at pH 3.5. Additionally, at pH 5.5 another fragment of basic protein, peptide 1 - 91, persisted indicating that under certain basic protein as well as basic protein peptide 43 - 169 may be cleaved in the molecular region of basic protein around the phenylalanyl-phenylalanine residues at position 88 - 89. The small amount of peptides 1 - 91 and 92 - 169 detected at pH 5.5 suggests that the bond between residues 91 and 92 in intact basic protein is a minor cleavage site. The options and variation in cleavage around residues 88 - 92 of basic protein presumably result from pH-dependent changes in conformation in the is region but could also be due to changes in conformation of cathepsin D. These results indicate that local tissue changes such a pH amy affect not only the velocity of the reaction but also the nature of th product formed by the degradation of basic protein by brain cathepsin D

Covalent structure of collagen: amino acid sequence of alpha 1(III)-CB9 from type III collagen of human liver

The peptide alpha 1(III)-CB9 was prepared and purified from human liver, and its amino acid sequence was determined. Automated Edman degradation of the intact peptide and peptides derived from selective cleavage with hydroxylamine and digestions with trypsin, thermolysin, and Staph V8 protease enabled determination of the complete amino acid sequence. The peptide alpha 1(III)-CB9 represents the COOH terminus of the helical (pepsin-resistant) portion of type III collagen and terminates in a Cys-Cys sequence responsible for the intramolecular disulfide cross-linkages with other chains. The present work completes the entire amino acid sequence of the helical (pepsin-resistant) portion of human cirrhotic liver type III collagen consisting of peptides alpha 1-(III)-CB3-7-6-1-8-10-2-4-5-9. The COOH terminus of human liver alpha 1(III) contained two additional triplets which, together with the extra triplet at the NH2 terminus in alpha 1(III)-CB3, make the helical portion of type III collagen longer than alpha 1(I) by nine residues (three Gly-X-Y triplets). The helical region of human liver type III collagen, therefore, consists of 1023 amino acids or 341 triplets.

Investigation of type I and type III collagens of the lung in progressive systemic sclerosis

The interstitial collagens, type I and type III, were investigated in lung tissue from patients with progressive systemic sclerosis (PSS) with pulmonary involvement. By use of CNBr digestion of whole tissue, the relative content of type I versus type III collagen was unchanged. This contrasts with idiopathic pulmonary fibrosis. Limited pepsin digestion released greater amounts of collagen (55%) than normal (16%), but the individual collagen chains were chemically indistinguishable. A reduced amount of the more stable collagen crosslink, hydroxylysinonorleucine, was observed which was consistent with the relatively greater degree of solubilization.

Specific cleavage of human type III collagen by human polymorphonuclear leukocyte elastase

Purified polymorphonuclear leukocyte elastase degraded native human liver type III collagen at 27 degrees C by making a cleavage through the triple helix. The enzyme had no effect on human type I collagen. The reaction was inhibited by phenylmethanesulfonyl fluoride (PhCH2SO2F) but not by EDTA. The collagen reaction products were identical with those generated by human rheumatoid synovial collagenase when analyzed by polyacrylamide gel electrophoresis and gel filtration. NH2-trminal sequence analysis indicated that the enzyme cleaved at an isoleucyl-threonyl bond located 4 residues on the carboxyl side of the established cleavage site for animal collagenases. Therefore, it is likely that in pathologic states, type III collagen can be selectively depleted from the matrix by this enzyme.

Interstitial collagen polymorphism in rat liver with CCl4-induced cirrhosis

The hepatotoxin, CCl4, was used to develop cirrhosis in rats in an attempt to compare fibrosis of this experimental disease with the alcoholic liver disease in humans. Several observations noted were as follows: (1) Collagen synthesis was increased by as much as 5-fold during the experimental period. Removal of the hepatotoxin led to a dramatic reduction of collagen synthesis within 2 weeks. The increased collagen synthesis was more marked after 21 and 80 days of CCl4 administration as compared with the rate after 200 days of administration. (2) Type III collagen from liver from rats with fibrosis was purified and eight CNBr-derived peptides characterized by molecular weight and amino acid composition. (3) After CNBr digestion of whole livers, quantitation of alpha 1(I)-CB8 and alpha 1-(III)-CB8 revealed that both type I and type III interstitial collagens, were increased by the same amount when measured in terms of either net synthesis or total collagen in the liver. At all stages, rat liver contained 35--40% type III collagen when compared with the total quantity of type I and type III interstitial collagens.

Covalent structure of collagen: amino acid sequence of alpha 1 (III)-CB5 from type III collagen of human liver

Type III collagen was prepared from human liver by limited pepsin digestion, differential salt precipitation, and carboxymethylcellulose chromatography. Ten distinct peptides were obtained by cyanogen bromide digestion. The peptide alpha 1 (III)-CB5 was further purified by carboxymethylcellulose chromatography, and its amino acid sequence was determined. Automatic Edman degradation of intact alpha 1 (III)-CB5, tryptic and thermolytic peptides, and hydroxylamine-derived fragments was used to establish the total sequence. The mammalian collagenase site contained in the alpha 1 (III)-CB5 sequence was ascertained by digestion of native type III collagen with purified rheumatoid synovial collagenase. Collagenase cleavage occurred at a single Gly--Ile bond, one triplet before the corresponding specific cleavage site of type I collagen. The present work brings the known sequence of human liver type III collagen to include alpha 1 (III)-CB3-7-6-1-8-10-2-4-5. These correspond to the homologous region of alpha 1 (I)-CB0-1-2-4-5-8-3-7 residues 11--804.

Effect of peptides of bovine myelin basic protein on dermal fibroblasts

Bovine basic protein (BP) was digested with purified bovine brain cathepsin D to produce well defined BP derived peptides 1-42, 43-88, 43-169, and 89-169. BP and these BP peptides were tested for their effects on cultured human dermal fibroblasts using a concentration range of 0.01-1,000 ng/ml. No effect was found on cellular proliferation, and neither total protein nor collagen synthesis was altered in the presence of these substances. Although preparations of brain which contain a fibroblast-growth factor also contain BP peptides, these results indicate that the purified BP peptides studied have no detectable biological effect on the growth of human dermal fibroblasts.

Collagen-platelet interaction. Type V(A-B) collagen induced platelet aggregation

One of the more recently discovered collagens, type V (or A-B) collagen, in its native fibillar form mediates human platelet aggregation and the release of serotonin. In agreement with a recent report, it has no detectable effect on human platelets in the soluble or amorphous form. The possibility that the observed results might be due to contaminating interstitial collagens was eliminated by taking advantage of unusual solubility properties of type V collagen. Type V collagen dissolved in 0.1M acetic acid formed native-type fibrils when dialyzed against PBS and amorphous fibrils when dislyzed against 0.05M Tris/0.13M NaCl, pH 7.4, at 4 degrees C. Interstitial collagens remained in solution under both of these conditions. In addition, type V collagen treated with sufficient, purified synovial collagenase to digest all contaminating interstitial collagen retained its platelet-aggregating properties. The purity of type V collagen was confirmed by SDS-PAGE of CNBr digests. These data indicate that the quaternary structure of type V collagen is important in its recognition by platelet membranes.

Immunoreactive myelin basic protein in the cerebrospinal fluid in neurological disorders

Cerebrospinal fluid from 582 persons was analyzed by a double-antibody radioimmunoassay for the presence of material cross-reactive with peptide 43-88 of human myelin basic protein (BP). In a group of 104 patients with multiple sclerosis (MS), 23 of 33 individuals clinically judged to have had an exacereation within two weeks prior to the time CSF was obtained had detectable material ranging from 2 to 200 ng/ml. In the remaining 71 MS patients who either were stable or had had an exacerbation more than two weeks before, only 1 patient had a marginally elevated level of immunoreactive material. CSF from 53 persons with cerebrovascular disease was studied, and 13 of 29 with recent infarctions had values of 2 to 540 ng/ml. The degree of elevation in strokes generally paralleled the predicted volume of the lesion, but the amounts detected did not correlate quite so closely temporally with onset as they did with the periods of active disease in MS. Of the remaining 425 patients, 29 had immunoreactive material of 2 to 400 ng/ml in their CSF. Most of these patients with detectable material had acute diseases known to affect the myelin sheath. Eight of 10 persons with acute disseminated encephalomyelitis had no detectable material. The presence in CSF of material cross-reactive with BP peptide 43-88 does not have diagnostic specificity for MS but can be used as a means for determining recent myelin injury. The type of BP peptide formed and mechanisms for clearance of BP and BP peptides may be important in determining the biological consequences following release of this potentially immunogenic material from the central nervous system.

Covalent structure of collagen: amino acid sequence of alpha 2-CB5 of chick skin collagen containing the animal collagenase cleavage site

The amino acid sequence of the 112 residues from the amino terminus of alpha 2-CB5 from chick skin collagen was determined by automated sequential degradation of intact alpha 2-CB5 and several chymotryptic and tryptic peptides. This segment of the peptide includes the site of the action of animal collagenases. As compared to the sequence around the alpha 1 cleavage site, the alpha 2 sequence is notable for the remarkable constancy of the residues to the amino side and the relative abundance of hydrophobic residues to the carboxyl side of the cleavage site, suggesting that these features are important in the recognition by the enzyme. The sequence of this region of the alpha 2 chain is consistent with the Gly-X-Y triplet structure and the preference of certain residues for either the X or Y position in distribution. However, three of the six residues of leucine were found in the Y position rather than the X position. Leucine residues were found only once in the Y position in the alpha 1 (I) chain. This preference does not appear to hold in the alpha 2 chain.