Immunohistochemical evidence for the presence of collagen type III in human arterial walls, arterial thrombi, and in leukocytes, incubated with collagen in vitro

Sensitivity of a two-dimensional biomorphoelastic model for post-burn contraction

We consider a two-dimensional biomorphoelastic model describing post-burn scar contraction. This model describes skin displacement and the development of the effective Eulerian strain in the tissue. Besides these mechanical components, signaling molecules, fibroblasts, myofibroblasts, and collagen also play a significant role in the model. We perform a sensitivity analysis for the independent parameters of the model and focus on the effects on features of the relative surface area and the total strain energy density. We conclude that the most sensitive parameters are the Poisson's ratio, the equilibrium collagen concentration, the contraction inhibitor constant, and the myofibroblast apoptosis rate. Next to these insights, we perform a sensitivity analysis where the proliferation rates of fibroblasts and myofibroblasts are not the same. The impact of this model adaptation is significant.

Decellularization of intact tissue enables MALDI imaging mass spectrometry analysis of the extracellular matrix

Matrix-assisted laser desorption/ionization imaging mass spectrometry (MALDI IMS) is a powerful molecular mapping technology that offers unbiased visualization of the spatial arrangement of biomolecules in tissue. Although there has been a significant increase in the number of applications employing this technology, the extracellular matrix (ECM) has received little attention, likely because ECM proteins are mostly large, insoluble and heavily cross-linked. We have developed a new sample preparation approach to enable MALDI IMS analysis of ECM proteins in tissue. Prior to freezing and sectioning, intact tissues are decellularized by incubation in sodium dodecyl sulfate. Decellularization removes the highly abundant, soluble species that dominate a MALDI IMS spectrum while preserving the structural integrity of the ECM. In situ tryptic hydrolysis and imaging of tryptic peptides are then carried out to accommodate the large sizes of ECM proteins. This new approach allows the use of MALDI IMS for identification of spatially specific changes in ECM protein expression and modification in tissue.

An MRI study of the differences in the rate of thrombolysis between red blood cell-rich and platelet-rich components of venous thrombi ex vivo

PURPOSE

To test whether T(1)-weighted MRI can detect the differences in the rate of thrombolysis induced by recombinant tissue plasminogen activator (rt-PA) between platelet-rich regions and red blood cell (RBC)-rich regions of venous thrombi ex vivo.

MATERIALS AND METHODS

Each of 21 venous thrombi ex vivo (8 pulmonary emboli and 13 in situ thrombi) was dissected along the longitudinal axis. Half of it was analyzed for the presence of platelet, fibrin, and RBC components by immunohistochemistry and the other half was imaged serially by high-resolution T(1)-weighted three-dimensional MRI to assess the progression of thrombolysis. The MR images were analyzed for proportions of the remaining platelet-rich and RBC-rich regions.

RESULTS

Laminated platelet-rich regions, corresponding to Zahn lines, were confirmed immunohistochemically and by MRI in 18/21 venous thrombi. In T(1)-weighted MR images (TE/TR = 10/105 ms) the mean signal intensity of platelet-rich regions was on average 2.3 higher than that of RBC-rich regions. The rate of thrombolysis in platelet-rich regions was on average 30% lower than in RBC-rich regions. After 120 min of thrombolysis the proportion of lysed platelet-rich regions was 0.27 ± 0.04 versus 0.40 ± 0.08 in RBC regions, which resulted in 1.4% decrease of lysed thrombus volume per 1% increase of platelet-rich content.

CONCLUSION

Venous thrombi are most often composed of interspersed platelet-rich and RBC-rich regions. T(1) -weighted MRI is capable of noninvasive discrimination between those two components of venous thrombi ex vivo which have a different susceptibility to thrombolysis by rt-PA.

Different role of platelet glycoprotein GP Ia/IIa in platelet contact and activation induced by type I and type III collagens

The role of glycoprotein Ia/IIa was studied during platelet contact and aggregation induced by type I and type III collagen. The anti-glycoprotein Ia/IIa (6F1) antibody inhibited type I collagen-induced aggregation but did not inhibit the first contact between platelets and collagen. In contrast, it was without effect either on type III collagen-induced contact or platelet interaction with the subendothelium in a static assay. Platelet aggregation induced by type III collagen was only slightly slowed down by 6F1 but pp72 spleen tyrosine kinase phosphorylation was not modified even at concentrations of 6F1 that completely blocked platelet activation induced by type I collagen. Our results indicate that glycoprotein Ia/IIa is not a primary binding site for type I or type III collagen on the platelet membrane. This receptor is more specifically involved in type I collagen-induced platelet spreading and aggregation.

Microfibrils from the arterial subendothelium

Microfibrillar structures of the subendothelium are represented by either type VI collagen or elastin-associated microfibrils which are also referred to as fibrillin-containing microfibrils. These structures are present throughout the subendothelium irrespective of the presence of elastin. The localization, structure, and protein composition of microfibrils are reviewed. The arterial subendothelium is thrombogenic despite its very low content in fibrillar collagens. This thrombogenicity is linked to the microfibrillar structures, essentially to type VI collagen and to thrombospondin-containing microfibrils. Their respective ability to bind the von Willebrand factor and to activate blood platelets is discussed.

Transglutaminase levels in Dupuytren's disease

By use of immunoperoxidase staining, tissue transglutaminase and aminopropeptide of collagen type III were localized to fibroblasts running within cords of Dupuytren's fascia. Quantitative analysis of transglutaminase revealed that activity levels were significantly higher in acutely contracting fascia than in chronic contractures. The results show that contractures in Dupuytren's fascia may be reflected by the level of transglutaminase activity in the tissue. Furthermore, it is suggested that isopeptide bond formation, involving collagen type III aminopropeptide moieties, may be the biochemical mechanism by which transglutaminase maintains the contracted state.

Spontaneous carotid-cavernous fistulae in Ehlers-Danlos syndrome Type IV. Case report

Spontaneous bilateral carotid-cavernous fistulae and cervical artery dissection is reported in a 20-year-old woman with Ehlers-Danlos syndrome Type IV. The clinical features of 16 previously published cases of spontaneous carotid-cavernous fistulae associated with Ehlers-Danlos syndrome Type IV are reviewed, for a total of 17 cases. The mean age of the 14 women and three men was 31.6 years. Only direct fistulae were encountered. Diagnostic neuroangiography carried morbidity and mortality rates of 36% and 12%, respectively; neuroradiological treatment resulted in death in one of six patients. The possible value of desmopressin in the management of these patients is discussed. In view of the risks of arterial puncture and surgery, the authors emphasize the importance of early recognition of Ehlers-Danlos syndrome.

Spatial disorder of collagens in the great vessels, associated with congenital heart defects

Surgical ablation of the cardiac neural crest from the chicken embryo results in persistent truncus arteriosus (PTA) and a change in the elastic laminae of the great vessels, wherein elastin and the elastin microfibril show significant spatial disorder. The purpose of this study was to test the hypothesis that the interstitial collagens would also be disordered in the elastic laminae of chicken embryos with PTA. The birefringence characteristics of interstitial collagen were examined to evaluate spatial ordering. The results showed that collagen in the elastic laminae assumed an orderly configuration of well-defined fiber bundles in the great vessel walls of control embryos, whereas vessels from embryos with PTA lacked any distinct spatial order. Collagens type I and III were localized in the vessel walls. Type III collagen was the principal collagen of the elastic laminae, but was absent from the intima of all vessels. In the elastic laminae of vessels from control embryos, collagen type III showed well-defined fiber bundles whereas embryos with PTA had diffuse collagen type III in poorly defined laminae that were not separated by discrete layers of smooth muscle cells. Collagen type I was a minor component of the elastic laminae but formed robust pericellular fiber bundles throughout the media and intima. Collagen type I fibers appeared to be coarsened and less uniform in the vessels from embryos with PTA.

Immunolocalization of collagen types I and III in the arterial wall of the rat

Collagen types I and III were located by immunofluorescence procedures in the aorta and coronary arteries of the rat. Type I collagen was most prevalent in the adventitia of the aorta with only small amounts present in the intima and media. Type III collagen appeared to be a significant component in the media of the aorta and also in the adventitia of both blood vessels. The intima and media of the coronary arteries did not stain strongly for either type I or III collagen. Neither staining procedure was altered with preincubation of the sections with hyaluronidase or chondroitinase ABC. These studies indicate that type III collagen is a major component of the adventitia which has previously not been recognized by immunohistochemical techniques, possibly due to masking of collagen staining with glycosaminoglycans.

An improved immunofluorescence technique for the histological examination of blood vessel tissue

Autofluorescence of elastic fibres in blood vessel samples is a common interference with the specific fluorescence of FITC-conjugated antibodies. Counterstaining with eriochrome black T changed the yellow-green colour of elastic fibres to dark red, thus turning a disturbing feature into a useful reference background. A second counterstain, p-phenylenediamine, visualized cell nuclei as an amber colour. To demonstrate the improvement of this staining technique, cryosections from blood vessel samples, derived from control veins, arteries and experimental aneurysms of different ages (15 to 99 month old) in 5 sheep, were stained with antibodies against procollagen III, collagen type IV, laminin, and nidogen. The specific distribution of these connective tissue components could now be related to the location of the elastic fibres and the cells (cell nuclei).

Ehlers-Danlos syndrome type IV (EDS IV) as model of a defective biopolymer composite material

The connective tissue of a lethal EDS IV case was investigated for the reasons of the manifested disturbances of the arterial wall. This functional disorder was attributed to the mechanical decoupling of elastin and collagen, with the premise of a composite material consisting of cellular, fibrillar, lamellar and other matrix components. A conceivable relation between the manifested deficiency of type III collagen and a disturbed anchoring of elastin is shown. These findings are supported by biochemical, morphological, x-ray and mechanical data.

Procollagen-III peptide serum levels in Paget's disease of the bone

A commercially available radioimmunoassay kit was used to determine aminoterminal procollagen-III peptide (pNcoll III) serum levels in patients with Paget's disease of the bone and control subjects. In patients with Paget's disease pNcoll III concentrations were significantly elevated. They decreased to varying degrees under chronic therapy with human and salmon calcitonin, disodium ethane 1-hydroxy 1,1-diphosphonate (EHDP), or a combination therapy of EHDP and human calcitonin. The results were compared with the effect on traditional biochemical markers of disease activity: serum alkaline phosphatase and urinary hydroxyproline excretion, both of which reacted more acutely to the various therapies than pNcoll III, although pretreatment correlations were close. The most probable source of pNcoll III is not the Pagetic bone per se, but the vascular, fibrous connective tissue replacing normal bone marrow.

Interstitial collagens and ageing in human aorta

Types I and III collagen were identified in four segments of human aorta using pepsin and cyanogen bromide digestion followed by sodium dodecyl sulphate polyacrylamide gel electrophoresis. Collagen is not uniformly distributed in the different segments of the arterial wall. Collagen type I is always the major collagen present. With ageing collagen type III decrease in quantity from the heart to the distal portion of the aorta. Histologically the elastic tissue is more altered in the lower abdominal section of aorta than in the arch. This study allowed a correlation between morphological observations and biochemical changes.

Localization of binding sites within human von Willebrand factor for monomeric type III collagen

Purified human plasma von Willebrand factor (vWf) binds to pepsin-digested monomeric type III collagen in a saturable (KD = 1 X 10(-8) M), specific, and rapid manner with a stoichiometry of approximately 1:15 [vWf subunit (Mr 270,000):collagen trimer (Mr 300,000)]. Two reduced and alkylated CNBr peptides of vWf, termed M11 residues 542-622 and M20 residues 948-998 [Titani, K., Kumar, S., Takio, K., Ericsson, L. H., Wade, R. D., Ashida, K., Walsh, K. A., Chopek, M. W., Sadler, J. E., & Fujikawa, K. (1986) Biochemistry 25, 3171-3184], inhibited vWf binding to collagen. With 125I-vWf (2 X 10(-9) M) as ligand, M11, M20, fragment III (a dimeric, V8 protease, NH2-terminal fragment, Mr 320,000 referenced above), and unlabeled vWf inhibited binding to collagen with EC50 values of 4.8 X 10(-7), 9.4 X 10(-7), 1.1 X 10(-7), and 0.2 X 10(-7) M, respectively. M11 and M20 bind to collagen directly when 125I-labeled peptides are used as ligands. Other CNBr fragments of vWf were less effective as inhibitors (5-fold or less) and bound less avidly to collagen (5-fold or less) compared to M11 and M20. A murine anti-human vWf monoclonal antibody (MR5), which blocks the binding of vWf to collagen, bound selectively to both M11 and M20 when tested in an enzyme-linked immunoadsorbent assay.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of collagen types I, III, IV and V, fibronectin and laminin in human arteries by the indirect immunofluorescence method

The distribution of types I, III, IV and V collagen and of the glycoproteins fibronectin and laminin in sections of human aortas, arteries and atherosclerotic plaques were studied using monospecific antibodies and indirect fluorescence microscopy. Types IV and V collagen and laminin were present in a narrow zone, representing the basement membrane, apposed to the endothelial layers of all these tissues. Types I and III collagen and fibronectin were located in the interstitial spaces of the intima and the media of blood vessels walls, whereas types IV and V collagen and laminin were found in the basement membranes underlying smooth muscle cells in these areas. Two types of atherosclerotic plaques were observed. Lipid-rich plaques contained less collagen and reduced amounts of the glycoproteins. Fibrous plaques consisted of regions deficient in types I and III collagen and collagen-rich regions with elevated levels of these two collagens as well as more fibronectin. The collagen-rich regions of fibrous plaques contained, however, little type IV and type V collagen and little of the glycoproteins laminin and fibronectin. This may be due to the reduced number of cells involved in the biosynthesis of these basement membrane proteins.

Morphological, histochemical and biochemical observations on the connective tissue matrix of in situ and isolated hepatic granulomas in experimental murine schistosomiasis

The connective tissue matrix of hepatic granulomas from Swiss mice, each infected with 20 Schistosoma mansoni cercariae, was examined using morphological, histochemical and biochemical methods, during the evolution of the disease. Evidence was obtained by both light and electron microscopy that suggested the presence of two different collagen populations which appeared successively during granuloma evolution. Morphological features suggesting the occurrence of collagenolysis were observed at the final stage of granuloma development. The connective tissue matrix of schistosome granulomas was devoid of elastic system fibres. Schistosome egg granulomas contain dermatan sulphate-proteoglycan.

Distribution of type I, III, IV and V collagen in normal and atherosclerotic human arterial wall: immunomorphological characteristics

35 autopsies--aged 30 to 75 years--were investigated in order to establish trends of collagen localization in various types of arteries depending on age, arterial size and degree of atherosclerosis. Cryostat sections stained with highly specific antibodies to human types I, III, IV or V collagen, or with the antiserum to smooth muscle myosin were examined by the indirect immunofluorescence technique. Localization of type III collagen was very similar to that of type I. Fibrous structures of both type I and type III were then major constituents of the intima, media and adventitia. Sparse fibrils of type I and type III collagens were revealed in the subendothelium of unaffected intima. They gradually became abundant in the deeper intimal layers contrasting with loose fibrillar formations of the media. The content of interstitial collagens was significantly increased in the subendothelium of local intimal thickenings and in a thickened intima of the aged. This fact, considering the thrombogenicity of interstitial collagens, may be relevant to the atherogenesis through the "response-to-injury" mechanism. Type IV and type V collagens are localized to the endothelial basement membrane and basement membranes of smooth muscle cells of the intima and media. Diffusely distributed type V collagen was also observed in the intercellular space of the intima. In lipid streaks, parallel layers of condensed interstitial collagens separated groups of cells and extracellular lipid depositions. In fibrous plaques, types I and III became prevalent structural elements and their densely packed fibers occupied whole regions devoid of any type IV and type V collagen. Heavily thickened type IV collagen structures surrounding individual smooth muscle cells were found in fibrous plaques, but never, in unaffected intima.

Reticulin and its related structural connective tissue proteins in the rheumatoid synovium

Argyrophilic reticulin fibres are an important component of the rheumatoid synovium and their distribution and that of their individual protein constituents have been studied in synovial biopsies from a series of 29 cases of rheumatoid arthritis. In acutely inflamed synovia they are predominantly found underneath the hyperplastic synovial lining layer and related to the inflammatory cell infiltrate. With developing chronicity the reticulin network is gradually replaced by mature collagen. This histological pattern is mirrored by changes in the individual components of reticulin fibres-fibronectin, the non-collagenous reticulin component of Pras and Glynn (NCRC) and collagen type III.

Comparison of the collagenous products synthesized in culture by pig aortic endothelial and smooth-muscle cells. Variability in endothelial-cell cultures

In contrast with smooth-muscle cells from the same tissue, endothelial cells from pig aorta were found to exhibit in culture considerable variability in the pattern of collagen synthesis between one isolation of cells and the next. Synthesis varied from largely collagen type I to virtually all type III in the absence of type I but with small amounts still of collagens types IV and V, to, in one instance, synthesis basically of only type V. Synthesis usually by these cells of collagen predominantly of the interstitial type (I and III) rather than, as might be expected, that from basement membrane (type IV) was not attributable to the influence of subculture. All four collagen types were deposited in the cell layer to an increased extent in primary compared with secondary cultures of either smooth muscle or endothelial origin. Endothelial cells appeared sometimes to synthesize a large-Mr collagenous entity that might conceivably be related to 'short-chain' collagen. In addition, small-Mr hydroxyproline-containing peptides were detected that might reflect rapid collagen(s) turnover in endothelial cultures.

Collagen of slow twitch and fast twitch muscle fibres in different types of rat skeletal muscle

The appearance of collagen around individual fast twitch (FT) and slow twitch (ST) muscle fibres was investigated in skeletal muscles with different contractile properties using endurance trained and untrained rats as experimental animals. The collagenous connective tissue was analyzed by measuring hydroxyproline biochemically and by staining collagenous material histochemically in M. soleus (MS), M. rectus femoris (MRF), and M. gastrocnemius (MG). The concentration of hydroxyproline in the ST fibres dissected from MS (2.72 +/- 0.35 micrograms X mg-1 d.w.) was significantly higher than that of the FT fibres dissected from MRF (1.52 +/- 0.33 micrograms X mg-1 d.w.). Similarly, the concentration of hydroxyproline was higher in ST (2.54 +/- 0.51 micrograms X mg-1 d.w.) than in FT fibres (1.60 +/- 0.43 micrograms X mg-1 d.w.), when the fibres were dissected from the same muscle, MG. Histochemical staining of collagenous material agreed with the biochemical evidence that MS and the slow twitch area of MG are more collagenous than MRF and the fast twitch area of MG both at the level of perimysium and endomysium. The variables were not affected by endurance training. When discussing the role of collagen in the function of skeletal muscle it is suggested that the different functional demands of different skeletal muscles are also reflected in the structure of intramuscular connective tissue, even at the level of endomysial collagen. It is supposed that the known differences in the elastic properties of fast tetanic muscle compared to slow tonic muscle as, e.g., the higher compliance of fast muscle could at least partly be explained in terms of the amount, type, and structure of intramuscular collagen.

Investigation of relationships between collagens, elastin and proteoglycans in bovine thoracic aorta by immunofluorescence techniques

Types I, III and V collagens and proteoglycan were localized in the aorta by indirect immunofluorescence techniques. Type I collagen was more prominent in media and adventitia than in intima while type III collagen predominated in intima and media but appeared less significant in adventitia. Type V collagen was observed in intima and media only and was seen surrounding smooth muscle cells. Type I collagen was located between elastic fibres but type III collagen appeared to envelop the fibres, suggesting an interaction between elastic fibres and type III collagen. Pretreatment of sections with testicular hyaluronidase caused no changes in staining for type I collagen, but adventitial areas showed increased staining for type III collagen. After digestion with chondroitinase ABC, intimal and medial areas showed increased staining for type III collagen. Therefore, type III collagen forms stronger interactions with proteoglycans and hyaluronic acid than does type I collagen and type III collagen in adventitia is largely masked by hyaluronic acid, while type III collagen in intima and media is associated with proteoglycan. Thus, type III collagen is a more significant component of adventitia than previously recognized. Proteoglycan was also partly localized along elastic fibres. It is, therefore, suggested that elastic fibres are coated with type III collagen, which itself is coated with proteoglycan.

Distribution of CL glycoprotein in tissues: an immunohistochemical study

CL glycoprotein is a collagen-like glycoprotein which we have recently isolated from rapidly growing fetal bovine, elastin-rich tissues. This protein has a molecular weight of approximately 140,000 daltons, contains hydroxyproline and hydroxylysine and is digested by highly purified collagenase to yield three large polypeptides. A specific antibody has been developed against this protein and has been used for immunofluorescence microscopy to study the distribution of CL glycoprotein in a range of tissues. It has been shown that the antibody localized in the intercellular matrix of nuchal ligament and aorta, of the non-elastic Achilles tendon and in complex tissues such as kidney, lung, skin and spleen. The antibody also localized to the surface of aortic smooth muscle cells-presumably to the basement membrane, but did not bind to other basement membranes, including the vascular subendothelial basement membrane. The pattern of distribution was similar in adult bovine tissues. As this antibody showed no avidity for elastic tissue elements, it is most unlikely that CL glycoprotein is a constituent of elastin-associated microfibrils. When the pattern of the CL glycoprotein distribution within the tissues was studied, it was found that, apart from its concentration around vascular smooth muscle cells, CL glycoprotein exhibited considerable overlap in distribution with the interstitial collagens. On the basis of these observations and having regard to its biochemical characteristics, it is proposed that CL glycoprotein has a structural role inter-linking interstitial components to one another and to vascular smooth muscle cells.

Type I and III collagens as a possible target for drug delivery to the injured sites of vascular bed

Interaction of anti-human collagen types I and III antibodies, as well as human red blood cells conjugated with these antibodies, with the surface of denuded intima of human aorta has been studied. Data on the accessibility of antigenic determinants of collagen types I and III for antibodies and red blood cells conjugated with these antibodies have been obtained in ex vivo experiments in an original model. On the basis of the obtained results it is concluded that antigenic determinants of collagen types I and III exposed as a result of blood vessel wall injury can serve as a target for drug delivery to the injured site(s).

What is collagen, what is not

Collagen represents a series of proteins that are broadly related in terms of chemical features, structure, and function. This presentation focuses on current information relevant to the function, chemistry, and structure of collagen in order to more precisely define the parameters within which a protein may be recognized as collagen. It is noted that ultrastructural investigation of collagen based on transmission and scanning electron microscopy alone is of limited value, but that chemical analyses of tissue specimens and the use of immunohistochemical techniques are essential in evaluating collagenous proteins in normal and pathologic tissues. In addition to the specific types of collagen (I-VI), the role of collagen in the biology and pathophysiology of connective tissue is discussed.

Cryptogenic fibrosing alveolitis: prediction of fibrogenic activity from immunohistochemical studies of collagen types in lung biopsy specimens

Collagen immunofluorescence studies were performed on biopsy specimens from 25 patients with cryptogenic fibrosing alveolitis. We studied the relationship of these results to the clinical, radiological, and physiological assessments of disease activity during six-month periods before and after the lung biopsy; to the appearances on routine histological examination; to the inflammatory cell proportions in bronchoalveolar lavage fluid; and to the response to treatment. Positive associations were observed between the presence of type III collagen and disease activity before (p less than 0.015) and after (p less than 0.02) lung biopsy. These were independent of clinical and routine histological features. The type-III-positive group also contained nine of the 11 responding to treatment. None of the type-III-positive patients had a quiescent or stable course. In contrast, most patients with no type-III-collagen fluorescence had a stable course over the time of this study and did not improve on treatment. It is suggested that collagen typing may be an additional useful method of assessing potentially reversible disease in cryptogenic fibrosing alveolitis.

D-penicillamine-induced angiopathy in rats. Changes in aortic collagen, glycosaminoglycans, DNA and RNA in rats treated with D-penicillamine

Male Sprague-Dawley rats were treated with D-penicillamine (D-pen) in doses of 100, 250 or 500 mg/kg per day for 10, 32, 42 or 70 days. In addition animals were examined 28 days after withdrawal from 42 day's treatment with D-pen at 100 or 500 mg/kg per day. Pair-fed rats served as controls. The changes in aortic collagen, glycosaminoglycans (GAGs), DNA and RNA were studied. D-Pen had a dose- and time-related solubilizing effect on aortic collagen, which regained normal resistance to extraction within 28 days after cessation of the treatment. In contrast, D-pen caused a progressive accumulation of hydroxyproline (Hyp) in the aortic wall during and after treatment, probably mediated by an increased number of matrix synthesizing cells, as judged by augmentation of the DNA content in the presence of unaltered Hyp/DNA and RNA/DNA ratios. The relative amount of type III collagen was increased after 500 mg/kg per day D-pen for 10 and 42 days. High doses of D-pen increased the percentage of water in the aortic wall and reduced the ratio of Hyp to total tissue protein, suggesting an increased content of water-binding substances. This was confirmed by GAG accumulation. Hyaluronic acid (HA) and chondroitin 4,6-sulphate (CHS) were predominant after 32 and 42 days, whereas CHS, heparan sulphate (HS) and dermatan sulphate (DS) prevailed after 70 days of treatment. These observations suggest that processes of repair and regeneration are elicited secondary to the inhibitory effect of D-pen on aortic collagen and elastin crosslinking. Hypertrophy of the vessel wall may imply an increased rigidity, resulting in further increase of the susceptibility to haemodynamic injury.

Collagen polymorphism in the normal and diseased blood vessel wall. Investigation of collagens types I, III and V

Estimation of collagens types I and III in pepsin digests and by analysis of specific cyanogen-bromide derived peptides by SDS-polyacrylamide gel electrophoresis, has indicated that both the undiseased human aortic media and the atherosclerotic plaque of the diseased intima contain more type I collagen than type III. There was only a relatively small shift in composition in favour of type I collagen in the diseased compared to the undiseased tissue. Diffusely thickened intima was similar in composition to the atherosclerotic plaque. These results suggest that both atherogenesis and diffuse intimal thickening may involve primarily smooth muscle cell hyperplasia with increased overall collagen production but little alteration in cell phenotype as regards the relative proportions of the individual collagens produced. They do not support the contention that atherosclerosis involves a 'transformation' of smooth muscle cells to fibroblast in type, whereby a major switch in synthesis occurs from largely type III collagen to mainly type I in disease. Type V collagen(s) containing both alpha A- and alpha B-chains has been detected throughout the vessel wall in diffusely thickened intima, media and adventitia, as well as in the plaque where, in the latter case, a marked enrichment relative to interstitial collagens was noted. This is presumed to reflect the relatively cellular nature of the atherosclerotic lesion. The alpha C-chain of type V collagen was detected in porcine but not human aorta.

Fibroblast growth factor modulates synthesis of collagen in cultured vascular endothelial cells

Vascular endothelial cells derived from adult bovine aortic arch can be grown in two ways, either in the presence or absence of fibroblast growth factor. The types of collagen produced by cultures under these two conditions have been compared. In the presence of fibroblast growth factor, cells grow in an orderly fashion, express their normal phenotype and synthesize primarily type III collagen plus collagens types IV and V at a ratio of 10:1:3. Cultures grown in the absence of the factor lose their orderly pattern of growth, lose polarity and normal phenotypic expression. They devote twice the proportion of total protein-synthesizing capacity to collagen, and now synthesize type I in addition to the other collagen types. The ratio of collagen types I:III:IV:V is approximately 30:70:1:13. The kinds of type V collagen chains expressed are also altered. Fibroblast growth factor appears to modulate collagen synthesis, the major component of the extracellular matrix, and indirectly modulates the phenotypic expression of cultured vascular endothelial cells. In atherosclerosis, type I collagen is found in association with the intimal layer. The disorderly growth and the abnormal production of type I collagen by these vascular endothelial cells cultured in the absence of fibroblast growth factor is a model for a number of pathological situations including atherosclerotic plaque formation.

Histologic study of the attachment of muscles to the rat mandible

The relationship of muscle to periosteum, tendon and ultimately to bone was studied in histological sections of rat mandibles aged 19 days in utero to 56 days postnatal. The following stains were employed: Van Gieson, Masson trichrome, Couciero and Friere, Gomori, orcinol-new fuchsin and Fullmer. Three modes of muscle attachment to the growing rat mandible were described according to the arrangement of collagen and reticular fibres at the interface between the bone and muscles. The morphological characteristics of the three modes persisted even in 56-day-old rats. The structure of the muscle-bone interface suggested a single mechanism of adaptation of muscles to bone during growth. With maturation, the size, number and variety of cells decreased and the size and thickness of collagen fibres increased in the muscle attachments. Each muscle was attached to the mandible by one or more types of attachment defined in this study. A schematic map of the distribution of the different attachment modes associated with muscles of the rat mandible was constructed. Distinction between these modes of attachment may be important in relating the form of a bone to its function.

Immunohistochemical study of collagen types in human foetal lung and fibrotic lung disease

Highly purified type-specific anti-collagen antibodies (prepared in animals to types I, II, III, and IV bovine collagen) were used in an indirect immunofluorescence method for the study of human lung collagen. The tissue localisation of each collagen type, and the apparent type I:III collagen ratio was assessed in normal foetal and adult lung and in fibrotic lung lesions. In the latter, the relationship of the findings to the natural history of the lesion was considered. This method was compared with routine connective tissue stains. The following observations were made. (1) Foetal lung in the canalicular phase of development proved a useful substrate for validating and standardizing the procedure. (2) Collagen fluorescence was more sensitive than connective tissue stains in detecting collagen in foetal tissues and sites of early fibrosis. (3) On the basis of collagen-type fluorescence, two distinctive patterns of fibrosis were recognised. Areas of mature collagen surrounding vessels and bronchi and in established scar tissue, for example in asbestotic pleural plaques, were virtually exclusively type I collagen. By contrast, areas of early active fibrosis like sarcoid nodules and organising pneumonia, which usually contained variable numbers of fibroblasts and chronic inflammatory cells, were characterised by an increased proportion of type III collagen and a greater intensity of both types I and III collagen fluorescence. The possible significance of this change in type III:I collagen ratio is discussed. Determination of the stage of fibrotic lesions by this method might have applications in the prediction of disease progression, and influence management of some conditions.

Distribution of fibronectin in the rectal mucosa

Fibronectin is a glycoprotein of high molecular weight present in tissues, plasma, and tissue fluids. Its distribution in the rectal mucosa was studied by immunofluorescent and immunoperoxidase techniques using a monospecific antiserum. Immunofluorescent reactivity for fibronectin was present in the normal rectal mucosa of control subjects in epithelial cells, on basement membranes, and as a loose cribriform network of extracellular reactivity in the lamina propria that codistributed with histochemically demonstrable reticulin. Fibronectin was demonstrated immunoelectromicroscopically on collagen fibres, on smooth muscle cells and within and between columnar epithelial cells. In the rectal mucosa of patients with colitis with marked inflammatory changes, fibronectin appeared thickened and more prominent when present on basement membranes and as sparse strands between inflammatory cells infiltrating the lamina propria. In patients with longstanding colitis and less inflammatory cell infiltration there was a diffuse increase in fibronectin which was densely and uniformly present throughout the lamina propria. Fibronectin is a structural component of the rectal mucosa and changes in its distribution may form an important part of the local reaction to inflammatory bowel disease.

Characterization of cell matrix associated collagens synthesized by aortic endothelial cells in culture

Several collagen types have been isolated and characterized from bovine aortic endothelial cells and their associated extracellular matrix. Two collagens, which comigrated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with the alpha 1(III), alpha 1(V), and alpha 2(V) collagen chains, were isolated by salt precipitation from pepsin digests of cell layer proteins. Two of these chains were further purified by molecular-sieve and ion-exchange chromatography and were identified as alpha 1(III) and alpha 1(V) by one-dimensional peptide maps generated with mast cell protease and cyanogen bromide. In contrast to type III collagen, which was found in both the culture medium and cell layer, type V collagen appeared to be restricted to the cell layer. In addition to their occurrence as cell layer constituents, both types III and V collagens were localized to an extracellular matrix after the cells had been removed from the culture dishes by detergent. Preliminary studies based on peptide maps comparing type III collagen from the cell layer and culture medium provide evidence for structural heterogeneity within this collagen type.

Collagen synthesis and turnover following particle phagocytosis in dermal fibroblasts

Dermal fibroblast collagens were isolated after cold pepsin/acetic acid extraction and characterized by differentiated salt precipitation, agarose molecular sieve chromatography, CM-cellulose chromatography, and identification of cyanogen bromide cleavage peptides. Subsequent to particle phagocytosis, collagens recovered as secretory products from latex-treated cells were quantitatively less in total collagen and deficient in type III collagen. Although the total levels of hydroxyproline synthesized were similar to control cell populations, hydroxyproline recovered as non-dialyzable material was only 32% of the total hydroxyproline synthesize. Recovery of exogenous labeled collagen following dialysis, molecular sieve chromatography (Bio-Gel A-5m), and [14C]proline pulse-chase labeling of endogenous collagen, indicates that the alteration in types and quantities of recoverable collagen chains are primarily the result of rapid intracellular turnover.

The distribution of collagen types I, III and V (AB) in normal and atherosclerotic human aorta

Collagen of types I, III and V has been identified and localised in adult human aorta, coronary arteries and atherosclerotic plaques using an indirect immunofluorescent method with specific antibodies to human collagen antigens. The distribution of the three types of collagen was distinct. Type I collagen was found around smooth muscle cells in the aortic media and in large amounts in the atherosclerotic plaque. Type III collagen was found in dense deposits alongside the elastic laminae in the aortic media and in diffuse intimal thickening. In the aortic media, there appeared to be more type III collagen than type I. The reverse was true in advanced atherosclerotic plaques. Type V collagen was distributed throughout the extracellular matrix in the aortic media and in the subendothelial region of plaques. These findings confirm earlier biochemical studies and suggest that a major shift in the nature of collagen synthesis occurs within advanced atherosclerotic plaques.

Importance of a collagen substratum for stimulation of capillary endothelial cell proliferation by tumour angiogenesis factor

Tumour extracts were obtained from rat Walker 256 carcinoma and examined for the presence of tumour angiogenesis factor (TAF) in vivo before being used in tissue culture experiments. Capillary endothelial cells derived from cow brain white matter were used to study the effects of TAF-containing tumour extracts on cell proliferation in vitro. The cells were grown on two types of substrata: (1) plastic tissue culture dishes and (2) hydrated gels made of rat tail tendon type I collagen. Human platelets or platelet-released factors were introduced into the system because of the many inter-relationships known to exist between platelets, collagen and endothelial cells. If trypsin was used during the preparation of TAT, the resulting batches stimulated endothelial cell proliferation only when the cells were growing on a collagen substratum and either platelets or platelet-released factors were present in the growth medium. If incubation with trypsin was omitted from the TAF extraction procedure, the resulting batches stimulated cell growth both on plastic and on collagen. A synergistic interaction also occurred between these TAF-containing tumour extracts and platelet-released factors. This effect was always more marked when the cells were growing on collagen than when on plastic. These data suggest that the nature of the substratum affects the response of the endothelial cells to TAF and to platelet-released factors.

Correlation in the human aorta of APO B fractions with tissue cholesterol and collagen content

The amounts of buffer- and Triton-extracted apo B (LDL-protein), as well as the sum of these two fractions, were correlated with the total tissue cholesterol and hydroxyproline content (as a measure of collagen) in grossly normal intima, fatty streaks, and fibrous plaques of human aortas obtained at autopsy. Quantitative values of buffer- and Triton-extracted apo B were obtained by sequentially extracting homogenates of aortic intima with an aqueous buffer and one containing Triton X-100, and measuring the apo B content in each extract by an electroimmunoassay relative to plasma LDL or Triton-treated LDL. Significant positive correlations were obtained between the following: tissue cholesterol and both buffer-extracted and total-extracted apo B in grossly normal intima; tissue cholesterol and Triton-extracted apo B in microdissected fibrotic caps and cores of fibrous plaques, as well as in whole plaques. A positive correlation was also obtained between tissue cholesterol and total-extracted apo B in the necrotic core. A significant negative correlation was found between Triton-extracted apo B and collagen in whole plaques. The calculated mean percent of total tissue cholesterol in the different aortic regions that could be present as part of an intact LDL particle were: 100% in grossly normal intima, 16% in fatty streaks, and 11% in fibrous plaques. The positive correlation between Triton-extracted apo B and cholesterol in plaques suggests one or both of the following: the extracellular pool of cholesterol or some material increasing concurrently with cholesterol interacts with apo B or another part of the LDL particle; or the apo B containing lipoprotein is trapped in the hydrophobic environment of extracellular lipid. Both possibilities would render the particle less soluble in aqueous buffers. The negative correlation between Triton-extracted apo B and tissue collagen and the lack of a significant correlation between buffer-extracted apo B and collagen content suggests that collagen is probably not responsible for apo B retention in the aortic intima.

Specific immunohistochemical localization of type I collagen in porcine periodontal tissues using the peroxidase-labelled antibody technique

Antibody against Type I collagen was raised in rabbits and purified by immunoadsorption on Sepharose-conjugated Types I and III collagen. The cross-reactivity of purified antibody to Type III collagen was found to be less than 0.5% by passive haemagglutination and less than 1.5% by radioimmunoassay. When paraffin sections of fixed and decalcified pig molars were incubated with purified antibody to Type I collagen, varying degrees of staining were observed in the ligament, gingiva, bone and cementum. The periodontal ligament adjacent to bone was more widely stained than that adjacent to cementum in some regions, whereas in others, no difference in staining could be discerned between the two halves of the ligament. The lamina propria of gingiva was stained, and this appeared to be most intense in the vicinity of the overlying epithelium. The fibrous component in the endosteal spaces, the dentine and the extracellular coronal elements in the pulp were generally stained. The impression obtained from the staining pattern is that Type I collagen is not restricted to particular regions of the periodontal ligament or the lamina propria of the gingiva.