Chemotactic attraction of human fibroblasts to type I, II, and III collagens and collagen-derived peptides

The chemotactice response of human dermal fibroblasts of type I, II, and III human collagens and collagen-derived peptides was quantitated by an in vitro assay. All three native human collagens and constituent alpha chains can serve as chemoattractants for fibroblasts in vitro. When type I, II, and III collagens were digested by bacterial collagenase, the resulting peptides were also chemotactic. In addition, synthetic di- and tripeptides containing hydroxyproline were also chemotactic for fibroblasts. Since collagen is degraded and remodeled at sites of tissue injury and inflammation, these findings suggest that collagen and collagen-degradation peptides might function as chemotactic stimuli for fibroblasts in vivo and attract these cells to effect repair of damaged tissue.

Differential expression of two basement membrane collagen genes, COL4A6 and COL4A5, demonstrated by immunofluorescence staining using peptide-specific monoclonal antibodies

Genes for the human alpha 5(IV) and alpha 6(IV) collagen chains have a unique arrangement in that they are colocalized on chromosome Xq22 in a head-to-head fashion and appear to share a common bidirectional promoter. In addition we reported a novel observation that the COL4A6 gene is transcribed from two alternative promoters in a tissue-specific manner (Sugimoto, M., T. Oohashi, and Y. Ninomiya. 1994. Proc. Natl. Acad. Sci. USA. 91:11679-11683). To know whether the translation products of both genes are colocalized in various tissues, we raised alpha 5(IV) and alpha 6(IV) chain-specific rat monoclonal antibodies against synthetic peptides reflecting sequences near the carboxy terminus of each noncollagenous (NC)1 domain. By Western blotting alpha 6(IV) chain-specific antibody recognized 27-kD monomers and associated dimers of the human type IV collagen NC1 domain, which is the first demonstration of the presence in tissues of the alpha 6(IV) polypeptide as predicted from its cDNA sequence. Immunofluorescence studies using anti-alpha 6(IV) antibody demonstrated that in human adult kidney the alpha 6(IV) chain was never detected in the glomerular basement membrane, whereas the basement membranes of the Bowman's capsules and distal tubules were positive. The staining pattern of the glomerular basement membrane was quite different from that obtained with the anti-alpha 5(IV) peptide antibody. The alpha 5(IV) and alpha 6(IV) chains were colocalized in the basement membrane in the skin, smooth muscle cells, and adipocytes; however, little if any reaction was seen in basement membranes of cardiac muscles and hepatic sinusoidal endothelial cells. Thus, both genes are expressed in a tissue-specific manner, perhaps due to the unique function of the bidirectional promoter for both genes, which is presumably different from that for COL4A1 and COL4A2.

Collagen polymorphism in idiopathic chronic pulmonary fibrosis

Collagens in normal human lung and in idiopathic chronic fibrosis were investigated in terms of their covalent structure and compared for possible alterations in the diseased state. Collagens were solubilized by limited digestion with pepsin under nondenaturing conditions, and after purification they, were fractionated into types I and III. Carboxymethylcellulose and agarose chromatography of both types I and III collagens, and amino acid and carbohydrate analyses of the resulting alpha-chains indicated that the alpha 1 (I), alpha 2, and alpha 1 (III) chains of normal human lung were identical with the human skin alpha-chains in all respects examined except that the normal lung chains contained higher levels of hydroxylysine. Examination of collagens obtained from the diseased lung revealed that the content of hydroxylysine of the alpha 1 (I) and the alpha 1 (III) chains appeared to be diminished as compared to the normal lung chains. The values, expressed as residues per 1,000 residues, are 7.1 and 8.3 for the alpha 1 (I) and the alpha 1 (III) chains, respectively, as compared to 10.0 and 11.1 for the alpha-chains from the normal tissue. The chromatographic properties and amino acid and carbohydrate composition of the alpha-chains from the diseased tissue were otherwise indistinguishable from those of normal lung. In addition, isolation and characterization of the CNBr peptides of alpha 1 (I), alpha 2 and alpha 1 (III) from the diseased lung revealed no significant differences from the CNBr peptides from other human tissues reported previously. Normal and diseased lungs were also digested with CNBr, and the resultant alpha 1 (I) and alpha 1 (III) peptides were separated chromatographically. The relative quantities of these peptides indicate that type III collagen constitutes 33% of the total collagen in normal human lung, with the remainder being type I, whereas in idiopathic chronic pulmonary fibrosis, the relative content of type III collagen is markedly diminished, ranging from 12 to 24% in different patients. These results indicate that an alteration in tissue collagen polymorphism as well as subtle variations in the collagen structure accompany the fibrotic process in the diseased state, and suggest that these alterations may have possible pathogenetic implications.

Modulation of fibroblast functions by interleukin 1: increased steady-state accumulation of type I procollagen messenger RNAs and stimulation of other functions but not chemotaxis by human recombinant interleukin 1 alpha and beta

Interleukin-1 (IL-1) is synthesized by and released from macrophages in response to a variety of stimuli and appears to play an essential role in virtually all inflammatory conditions. In tissues of mesenchymal origin (e.g., cartilage, muscle, bone, and soft connective tissue) IL-1 induces changes characteristic of both destructive as well as reparative phenomena. Previous studies with natural IL-1 of varying degrees of purity have suggested that it is capable of modulating a number of biological activities of fibroblasts. We have compared the effects of purified human recombinant (hr) IL-1 alpha and beta on several fibroblast functions. The parameters studied include cell proliferation, chemotaxis, and production of collagen, collagenase, tissue inhibitor of metalloproteinase (TIMP), and prostaglandin (PG) E2. We observed that hrIL-1s stimulate the synthesis and accumulation of type I procollagen chains. Intracellular degradation of collagen is not altered by the hrIL-1s. Both IL-1s were observed to increase the steady-state levels of pro alpha 1(I) and pro alpha 2(I) mRNAs, indicating that they exert control of type I procollagen gene expression at the pretranslational level. We found that both hrIL-1 alpha and beta stimulate synthesis of TIMP, collagenase, PGE2, and growth of fibroblasts in vitro but are not chemotactic for fibroblasts. Although hrIl-1 alpha and beta both are able to stimulate production of PGE2 by fibroblasts, inhibition of prostaglandin synthesis by indomethacin has no measurable effect on the ability of the IL-1s to stimulate cell growth or production of collagen and collagenase. Each of the IL-1s stimulated proliferation and collagen production by fibroblasts to a similar degree, however hrIL-1 beta was found to be less potent than hrIL-1 alpha in stimulating PGE2 production. These observations support the notion that IL-1 alpha and beta may both modulate the degradation of collagen at sites of tissue injury by virtue of their ability to stimulate collagenase and PGE2 production by fibroblasts. Furthermore, IL-1 alpha and beta might also direct reparative functions of fibroblasts by stimulating their proliferation and synthesis of collagen and TIMP.

Establishment by the rat lymph node method of epitope-defined monoclonal antibodies recognizing the six different alpha chains of human type IV collagen

A group of rat monoclonal antibodies recognizing the six different alpha chains of human type IV collagen have been established by our novel method. The method is designated the rat lymph node method in which enlarged medial iliac lymph nodes of a rat injected with an antigen emulsion via hind footpads are used as a source of B cells for cell fusion to produce hybridomas. The immunogens used were synthetic peptides having non-consensus amino acid sequences near the carboxyl termini of type IV collagen alpha chains. Hybridomas were screened both by ELISA with synthetic peptides and by indirect immunofluorescence with cryostat sections of human kidneys. Because the epitopes of all antibodies were determined by multipin-peptide scanning, they were confirmed to be isoform-specific. They are useful for identification of alpha chains of type IV collagen at the protein level in normal and abnormal conditions. The combined use of synthetic peptides as immunogens, the rat lymph node method as making monoclonal antibodies, and the multipin-peptide scanning as epitope mapping is found to be a strong tool for identification of peptides and proteins whose amino acid sequences are known or have been deduced.

Collagen polymorphism in normal and cirrhotic human liver

Collagens in normal human liver and in alcoholic cirrhotic liver were investigated. Collagens were solubilized by limited proteolysis with pepsin under nondenaturing conditions, and after purification, were fractionated into types I and III by selective precipitation with NaCl. After carboxymethyl cellulose and agarose chromatography, the resulting alpha-chains from each of the collagen types were analyzed with respect to their amino acid and carbohydrate compositions. A comparison of the results obtained from normal liver with those from the diseases organ revealed no significant differences. The isolated human liver alpha1(I) and alpha1(III) chains were digested with CNBr and the generated peptides were separated and purified by a combination of ion-exchange and molecular sieve chromatography. The molecular weight and the amino acid and the carbohydrate compositions of each of the peptides were identical to those of the corresponding human skin peptides except for the slightly higher content of hydroxylysine in some of the peptides. The relative content of type III in relation to type I collagen in both normal anc cirrhotic liver was determined by digesting washed liver homogenates directly with CNBr and quantitating the resultant alpha1(I) and alpha 1(III) peptides after chromatographic separation. The relative quantities of these peptides indicated that normal human liver contained an average of 47% type III, with the remainder being type I. Cirrhotic liver, on the other hand, contained a significantly smaller proportion of type III, ranging from 18 to 34% in different samples, with a corresponding increase in type I. These findings indicate that although the amino acid and carbohydrate compositions of collagens deposited in cirrhotic liver are normal, the fibrotic process of alcoholic liver disease in humans is accompanied by an alteration in tissue collagen polymorphism, and suggest that the observed alterations may have pathogenetic implications.

Collagen-induced arthritis in mice: synergistic effect of E. coli lipopolysaccharide bypasses epitope specificity in the induction of arthritis with monoclonal antibodies to type II collagen

DBA/1 mice develop a chronic peripheral arthritis after immunization with type II collagen termed collagen-induced arthritis. We have localized the main arthritogenic determinants of CB11, a CNBr-generated arthritogenic fragment of chick type II collagen (CII), using 3 smaller peptide fragments of CB11 generated by endoproteinase LysC, LysC1 (CII 124-290), LysC2 (CII 291-374) and LysC3 (CII 375-402) and a panel of monoclonal antibodies (mAb) specific to CB11. MAb specific to the arthritogenic region of CB11 were also used to study the synergistic effect of E. coli lipopolysaccharide (LPS) on antibody-mediated arthritis in naive DBA/1 mice. LysC2 contained a minimum essential arthritogenic fragment of type II collagen: LysC2 induced arthritis by active immunization, also, a combination of four mAb specific to LysC2 passively transferred arthritis to naive mice. A single i.p. injection of LPS (50 micrograms/mouse) reduced the threshold values of the arthritogenic dose of mAb from 1 mg to 50 micrograms/clone per mouse, and decreased the number of mAb required for inducing arthritis from 4 to 2 clones. These observations suggest that LysC2, an 84 amino acid residue fragment, contains the main arthritogenic determinants within chick CB11. Importantly, LPS, a strong inducer of pro-inflammatory cytokines, negates the required multiple epitope specificity of autoantibodies in the passive transfer model and acts synergistically in the induction of arthritis by autoantibody.

Fibroblast chemotaxis induction by human recombinant interleukin-4. Identification by synthetic peptide analysis of two chemotactic domains residing in amino acid sequences 70-88 and 89-122

Interleukin-4 is a T lymphocyte- and mast cell-derived cytokine with pleiotropic properties with biological effects on a variety of target cells including B and T lymphocytes, macrophages, hematopoietic cells, mast cells, and fibroblasts. In addition to the proliferation effect of IL-4 on fibroblasts, which has been previously described, in this report the chemotactic properties of IL-4 for fibroblasts is described. Human recombinant IL-4 induced the chemotactic migration of dermal fibroblasts in vitro in modified Boyden-type chambers at concentrations between 10(-12) and 10(-11) M. The chemotactic activity of IL-4 was neutralized by anti-human recombinant IL-4 IgG antibodies. Oligopeptides representing the complete deduced amino acid sequence of human IL-4 were synthesized by the Merrifield technique and tested for their ability to induce fibroblast chemotaxis. Two peptides representing residues 70-88 and 89-122 induced fibroblast migration. Peptide 70-88 was the more potent of the two causing chemotaxis of fibroblasts at 10(-8)-10(-6) M while peptide 89-129 induced migration at 10(-7)-10(-5) M. Although the mechanism by which IL-4 and these two peptides induce fibroblast chemotaxis is unknown, each of these three compounds were able to chemotactically desensitize fibroblasts to the chemotactic effects of the other two but not to a structurally unrelated chemotactic cytokine, transforming growth factor beta-1. These studies suggest that IL-4 might function in vivo to induce the accumulation of fibroblasts at sites of tissue injury, inflammatory and immune reactions in which T lymphocytes and mast cells participate.

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.

Purification and properties of M protein extracted from group A streptococci with pepsin: covalent structure of the amino terminal region of type 24 M antigen

M protein was extracted from type 24, group A streptococci with pepsin at pH 5.8 and was further purified by ammonium sulfate precipitation, ribonuclease digestion, ion-exchange chromatography, and isoelectric focusing. The purified pepsin extract of M (pep M) protein was shown to be free of nontype-specific immunoreactivity in (a) complement fixation tests with heterologous M antiserum, (b) skin tests in normal adult guinea pigs, and (c) passive hemagglutination tests for the presence of lipoteichoic acid sensitizing or antigenic activity. The pep M24 was highly immunogenic; two of three rabbits developed opsonic antibody titers of 1:256 and the third a titer of 1:32 6 wk after a single injection of 100-pg doses of pep M24 emulsified in complete Freund's adjuvant. The antisera lacked nontype-specific antibodies and produced single precipitin lines in agar gel diffusion tests against crude HC1 extracts of the homologous M protein. Thus, the type-specific antigenic determinant(s) of type 24 M protein appears to be separable from immunotoxic, cross-reactive antigens without loss of immunogenicity in rabbits. The mobility of pep M24 upon electrophoresis in 10 percent sodium dodecyl sulfate pelyacrylamide gel was consistent with an average mol wt of 33,500 daltons. Amino acid analysis demonstrated a predominance of alanine, followed by glutamic acid, lysine, leucine, and aspartic acid. Pep M24 contained an estimated six to seven methionine residues and approximately ten phenylalanine residues per molecule. No other aromatic amino acids were detected. Automatic Edman degradation of pep M24 yielded the sequence of the first 29 amino acids (the amino terminal amino acid being valine) of the amino terminal region of the molecule. The detection of only one new amino acid at each step of Edman degradation confirmed the homogeneity of the purified pep M24.

Isolation, characterization and immunolocalization of a 53-kDal dentin sialoprotein (DSP)

We isolated a sialic-rich protein from rat dentin extracts and have named it dentin sialoprotein, DSP (formerly called 95K glycoprotein). DSP is rich in aspartic acid, glutamic acid, glycine and serine, but contains no cysteine or phosphate. The 30% carbohydrate content includes about 9% sialic acid and indicates that several N-glycosides and O-glycosides are present. Sedimentation equilibrium analysis gave a M(r) of 52,570. Based on this molecular weight we calculated that DSP contains about 350-amino acids and 75 monosaccharides. With automated Edman degradation the sequence of the first 8-amino acids was shown to be: Ile-Pro-Val-Pro-Gln-Leu-Val-Pro. The initial 3 residues of this sequence are identical to the first 3 in human osteopontin (OPN) and are closely similar to the Leu-Pro-Val sequences of OPN from other species, as well as at the beginning of bone acidic glycoprotein-75 (BAG-75). On Western immunoblots, purified polyclonal antibodies reacted only with DSP in dentin extracts and with none of the proteins from bone. Similarly, immunolocalization experiments showed the presence of DSP in dentin but not in enamel or alveolar bone. Along with immunohistochemical localization data reported elsewhere, these observations suggest that DSP may be an important marker for cells in the odontoblast lineage.

Regulation of TGF beta gene expression in rat liver intoxicated with carbon tetrachloride

Transforming growth factor beta (TGF beta) has been implicated as having a central role in the postinflammatory tissue regeneration and fibrosis. To test its potential involvement in events that follow hepatotoxin-mediated liver regeneration and fibrosis, we quantitated changes in the steady-state levels of TGF beta mRNA in parenchymal and nonparenchymal cells at various times after an acute treatment with CCl4, and also compared TGF beta gene expression in these two cell types from livers subjected to chronic CCl4 treatment. The parenchymal and nonparenchymal cells from normal liver contained undetectable amounts of TGF beta mRNA. In contrast, we could readily detect TGF beta specific transcripts in both the parenchymal and nonparenchymal cells after acute injury. Nonparenchymal cells from acutely injured liver contained fivefold greater amounts of TGF beta mRNA, which peaked at 48 h and declined thereafter. In chronically treated rat livers (1, 2, 3, and 7 wk after the initiation of CCl4 treatment), increased expression of TGF beta mRNA was found only in nonparenchymal cells obtained after 2-3 wk of treatment. Strikingly large elevations in the steady-state levels of beta-actin mRNA in CCl4-treated liver were also observed, which may be related to the known regenerative processes associated with acute liver toxicity. Changing dynamics of TGF beta gene expression, therefore, appear to be an important attribute of regenerating liver after acute or chronic CCl4 toxicity.

Stimulation of fibroblast chemotaxis by human recombinant tumor necrosis factor alpha (TNF-alpha) and a synthetic TNF-alpha 31-68 peptide

Macrophages are a major source of fibrogenic factors that promote healing of injured tissue. The recruitment of fibroblasts to sites of tissue injury is a prerequisite for optimal repair of tissue damage. In the present study, human recombinant tumor necrosis factor alpha (hrTNF-alpha), a major macrophage-derived cytokine, was demonstrated to be a potent fibroblast chemoattractant, inducing migration at picomolar concentrations. Anti-hrTNF-alpha monoclonal antibody neutralized most of the fibroblast chemotactic activity generated during short-term culture of human peripheral blood monocytes stimulated with bacterial lipopolysaccharide, suggesting that TNF-alpha is a major monocyte-derived fibroblast chemoattractant. The portion of the human TNF-alpha molecule responsible for its chemotactic stimulation of fibroblasts appears to reside in residues 31-68. This region is highly conserved between TNF-alpha and lymphotoxin. This peptide is not only itself chemotactic but is also able to block the chemotactic response of fibroblasts to hrTNF-alpha and vice versa, suggesting that they each mediate fibroblast migration through similar mechanisms. These data further underscore the potential importance of TNF-alpha in modulating a variety of fibroblast functions, including chemotaxis and synthesis of collagen, glycosaminoglycans, interleukin 1 alpha (IL-1 alpha) and -beta, human histocompatibility leukocyte antigen A and B antigens, collagenase, prostaglandin E2, and IL-6.

Profiles of steady state levels of messenger RNAs coding for type I procollagen, elastin, and fibronectin in hamster lungs undergoing bleomycin-induced interstitial pulmonary fibrosis

We have characterized the messenger RNAs (mRNAs) coding for procollagen alpha 1(I), elastin, fibronectin, and actin in the lungs of Syrian golden hamsters by Northern blot analyses. While elastin, fibronectin, and beta-actin were each coded for by a single mRNA species of 4.1 kilobases (kb), 9.1 kb, and 2.1 kb in size, respectively, we identified a major (5.4 kb) and a minor (6.5 kb) procollagen alpha 1(I) mRNA species in the hamster lungs. The mRNAs for the three extracellular matrix proteins showed increased accumulation followed by steady decline in the bleomycin-treated lungs. There were significant differences among the three mRNAs in the relative increase and the time of maximum accumulation. After reaching the peak levels between 2-3 wk posttreatment, the levels of procollagen alpha 1(I) and elastin mRNAs declined to near normal values around the fourth week. In contrast, the accumulation of fibronectin mRNA was maximum in the first week after bleomycin treatment. The procollagen alpha 1(I) mRNA accumulated most dramatically (sevenfold above the levels in the untreated animals) compared with a five-fold increase in mRNA coding for fibronectin. Elastin mRNA increased approximately twofold above the control values. Nuclear runoff transcription experiments demonstrated a selective increase in the rates of transcription of genes coding for procollagen alpha 1(I), fibronectin, and elastin; the extent of transcriptional stimulation of procollagen alpha 1(I) and fibronectin genes was significantly greater than that of elastin. Since the amount of actin mRNA, as well as the rate of transcription of actin gene(s), varied only slightly after bleomycin treatment, we conclude that the metabolism of mRNAs coding for extracellular matrix proteins may be preferentially perturbed during pulmonary fibrosis.

Processing of TCP pilin by TcpJ typifies a common step intrinsic to a newly recognized pathway of extracellular protein secretion by gram-negative bacteria

Biogenesis of the Vibrio cholerae toxin-coregulated pilus (TCP) requires the activities of at least seven accessory proteins. We demonstrate that a portion of this pathway involves a novel processing step in which a hydrophilic leader peptide is proteolytically removed from TcpA by the gene product characterized in this report, TcpJ, to yield the mature, export-competent form of the pilin. Cleavage of the pilin leader peptide is independent of known signal peptidases as demonstrated by pilin-processing profiles in Escherichia coli strains conditionally defective for production of leader peptidase or grown in the presence of the antibiotic globomycin. Additionally, pilin cleavage did not rely on the SecA protein, as evidenced by TcpA processing in azide-treated cells. These results suggest that TcpJ is representative of a new class of proteins involved in SecA-independent proteolytic cleavage of a set of atypical leader peptides during extracellular export.

Purification of a type V collagen degrading metalloproteinase from rabbit alveolar macrophages

A proteinase capable of degrading the helical region of native human type V collagen was identified in serum-free culture medium from "in vivo-activated" rabbit alveolar macrophages. This enzyme was purified to homogeneity using a combination of gel-filtration, ion-exchange and affinity chromatography. Analysis of the purified material by gel electrophoresis revealed a single broad band with relative molecular mass of 82,000 daltons Enzyme activity was eluted from the gel in a region corresponding to the stained band. The protein band was also found to stain positively using the periodic acid-Schiff technique indicating that it was glycosylated. Amino acid analysis revealed a composition rich in acidic residues. The enzyme cleaved type V collagen into three large molecular weight doublets consistent with two cleavage sites within the helix but was inactive against native type I collagen. However, when type I or type V collagen was heat-denatured, the enzyme degraded the alpha chains to small molecular weight peptides.

Identification of an immunosuppressive epitope of type II collagen that confers protection against collagen-induced arthritis

We have previously reported that collagen-induced arthritis can be suppressed by intravenous injection of native type II (CII) but not type I collagen. We have now identified denatured fragments of CII capable of suppressing collagen-induced arthritis and inducing tolerance. Purified CII was cleaved with cyanogen bromide (CB), and the major resulting peptides were isolated. Female DBA/1 mice were administered OVA, native CII, or one of the CB peptides, intravenously, before immunization with native CII, 6 wk after immunization, mice tolerized with CII and CB11 had a markedly lower incidence of arthritis compared with controls. There was a correlation between the overall antibody response and the incidence of arthritis. In addition, animals tolerized with either CII or CB11 had a decreased antibody response not only to CII, but also to each of the other CB peptides tested. To identify the epitope involved in suppression of arthritis, five synthetic peptides, 21-26 amino acids in length, corresponding to selected regions of CB11, were generated. Each of the peptides was injected intravenously into mice before immunization. Only one of these, CB11 122-147, was capable of suppressing arthritis. In addition, mice given the synthetic peptide CB11 122-147 neonatally were suppressed for arthritis and antibody responsiveness when immunized with CII at 8 wk of age. Thus, we have identified CB11 122-147 as an epitope of CII important in induction of tolerance and suppression of disease. Further experiments narrowing down the pivotal amino acids for the immunogenicity of this epitope and the role this epitope plays in induction and regulation of disease will enhance our understanding of how the immune response to collagen affects autoimmune arthritis.

Collagens of normal and cirrhotic human liver

The collagens of normal and end-stage alcoholic cirrhotic human liver were investigated. Mild conditions of pepsin digestion were employed to preserved the more pepsin sensitive type IV collagen molecules while increasingly more harsh conditions were used which solubilized the type I and type III hepatic collagens. The total hepatic collagen content was elevated from 1.8-2.1 in normal liver to 7.3-8.2 percent in the end-stage alcoholic liver. The graded pepsin digestion resulted in solubilization of 76-90 percent of the total hepatic collagen. The genetically distinct types of collagen were fractionated into types I, III, IV and V preparations using judicious salt precipitation from dilute acid and neutral pH solutions. The average distribution of collagen was 42.5, 39.5, 6.9 and 10.6 percent types I, III, IV and V collagen respectively in normal liver compared to 56.6, 28.0, 5.5 and 9.6 percent respectively in the end-stage alcoholic livers. An additional 0.6 and 0.5 percent in normal and end-stage cirrhotic liver respectively were located in a fraction separating out of the salt concentration required for type VI collagen. The type IV collagen of basement membrane was separated into the constituent 95Kda alpha 1(IV) and alpha 2(IV) polypeptide chains by Agarose A 5m gel filtration with subsequent (carboxymethyl) CM-cellulose chromatography. These chains were indistinguishable from similar chains of type IV collagen isolated previously from human placenta. The type V collagen alpha chains, alpha 1(V) and alpha 2(V) were purified by a combination of Diethylaminoethyl (DEAE) and CM-cellulose chromatography. The individual chains were fragmented with cyanogen bromide to yield 9 peptides from the alpha 1(V) chain and 10 peptides from the alpha 2(V) collagen chain. These were purified and analyzed for amino acid content and molecular weight. The study suggests that all collagen types were elevated in the end-stage alcoholic liver, but type I collagen was disproportionately increased over all other collagens. These results are consistent with previous studies which demonstrated an elevated type I collagen in other fibrotic conditions such as lung fibrosis and hypertrophic scar. They do not, however, agree with the suggested disproportionate elevation of type V collagen in human alcoholic liver. The reasons for this discrepancy are discussed.

Immunoidentification of type XII collagen in embryonic tissues

We have generated a monoclonal antibody against a synthetic peptide whose sequence was derived from the nucleotide sequence of a cDNA encoding alpha 1(XII) collagen. The antibody, 75d7, has been used to identify the alpha 1(XII) chain on immunoblots of SDS-PAGE tendon extracts as a 220-kD polypeptide, under reducing conditions. Amino-terminal amino acid sequence analysis of an immunopurified cyanogen bromide fragment of type XII collagen from embryonic chick tendons gave a single sequence identical to that predicted from the cDNA, thus confirming that the antibody recognizes the type XII protein. Immunofluorescence studies with the antibody demonstrate that type XII collagen is localized in type I-containing dense connective tissue structures such as tendons, ligaments, perichondrium, and periosteum. With these data, taken together with previous results showing that a portion of the sequence domains of type XII collagen is similar to domains of type IX, a nonfibrillar collagen associated with cross-striated fibrils in cartilage, we suggest that types IX and XII collagens are members of a distinct class of extracellular matrix proteins found in association with quarter-staggered collagen fibrils.

Localization of protective epitopes within the pilin subunit of the Vibrio cholerae toxin-coregulated pilus

From a collection of monoclonal antibodies (MAbs) that recognize the native structure of the toxin-coregulated pilus of Vibrio cholerae, two protective MAbs (16.1 and 169.1) were used to localize the corresponding epitopes on the pilus. These MAbs were shown to specifically recognize the carboxyl half of the TcpA pilin subunit, as determined by their recognition of proteolytic fragments and hybrid pilin proteins. The positions of the epitopes were precisely determined through the use of overlapping synthetic peptides corresponding to this region of the pilin. The MAbs were found to recognize adjacent peptides, delineating a region between residues 157 and 199. Since the protective nature is specific for these two antibodies, the findings suggest that this region defines a domain that participates in toxin-coregulated pilus-mediated colonization and therefore represents a target for studies of its potential as an immunogen for incorporation into a component cholera vaccine.

Human alpha 1(III) and alpha 2(V) procollagen genes are located on the long arm of chromosome 2

The multigene procollagen family encodes probably greater than 20 genetically distinct but structurally related polypeptide chains. Recent characterization of human procollagen clones has allowed determination of functional domains within the proteins, genomic organization, and chromosomal location. Previously, we assigned the coordinately expressed type I genes (alpha 1 and alpha 2) to chromosomes 17 and 7, respectively, and now other investigators have mapped the type II gene to chromosome 12 [Strom, C. M., Eddy, R. L. & Shows, T. B. (1984) Somatic Cell Genet. 10, 651-655]. Recently, we isolated cDNA clones encoding the fourth interstitial procollagen, type III, and the alpha 2 chain of the type V cytoskeletal components. To determine whether these genes were clustered with alpha 1(I), alpha 2(I), or alpha 1(II) or were further dispersed in the genome, in situ hybridization of the alpha 1(III) and alpha 2(V) probes to metaphase chromosomes was carried out. Here we report a fourth autosome with procollagen gene loci but the first cytological evidence for linkage. By using normal and translocated cell lines, our results show that both the alpha 1(III) and alpha 2(V) procollagen genes map to the q24.3----q31 region of chromosome 2.