Collagen polymorphism in experimental granulation tissue

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.

Biochemistry and histology of the connective tissue of Dupuytren's disease lesions

When compared to age-matched control aponeurosis, lesions of Dupuytren's disease contain higher contents of water, collagen and chondroitin-sulphate, as well as increased proportions of soluble collagens and of reducible cross-links; these indicate synthesis of new collagen. The lesions show also increased amounts of type III collagen and an increased hydroxylation and glycosylation of the reducible cross-links. All these parameters are characteristic of granulation and scar tissues. Type III collagen was located by means of immunofluorescence on thin argyrophilic fibres and also within the large fibre bundles which appeared to be disrupted into microbundles. The increase of type III collagen and the presence of myofibroblasts in the apparently unaffected aponeurosis show that the disease is widespread and suggest that it is initiated within the aponeurosis and propagated by the cells migrating along the collagen bundles.

The effect of immobilization on the types of collagen synthesized in periarticular connective tissue

The distribution of collagen types was studied in control and immobilized periarticular connective tissue to test the hypothesis that inflammatory tissue is the basis of the contracture process. The hypothesis derives from the fact that Type III collagen is prominent in inflammatory processes. The content of Type I and Type III collagen was determined by standard differential salt precipitation of the pepsin solubilized collagen, followed by resolution of the subunits on CM-cellulose. Analysis of the peptide fragments produced by cyanogen bromide was performed and their distribution determined by SDS gel electrophoresis. The collagen of control and immobilized periarticular connective tissue proved to be entirely Type I. Type III was not present. The periarticular connective tissue contracture process, therefore, is different from the intraarticular process in which fibrofatty connective tissue proliferation is prominent.

Quantitative assay of types I and III collagen synthesized by keloid biopsyes and fibroblasts

Molecular sieve column chromatography was used to determine the amount of type I and III collagen synthesized by normal dermis and keloid biopsies and fibroblasts derived from these tissues. After incubation with radioactive proline, the collagen was extracted and separated into types I and III and then quantitated. There was no significant difference in the percent type III collagen synthesized by fresh keloid biopsies compared to normal dermis. Likewise, there was no significant difference in the percent type III collagen synthesized by keloid fibroblasts compared to normal dermal fibroblasts. However, fibroblasts from both keloid and normal dermis synthesized a lower percentage of type III collagen in cell culture compared to the original biopsies. These findings demonstrate that keloid collagen has the same type distribution as normal dermis and suggest that increased collagen synthesis in these lesions is not related to altered collagen types.

Characterization of dermal collagen in systemic sclerosis

The amount of dermal collagen is increased in systemic sclerosis. However, unlike certain inflammatory conditions, the relative proportions of Type I and Type III collagens are closely similar to those found in normal adult dermis. Similarly, no change in the distribution of the collagen types could be detected by immunofluorescent staining, although a considerable thickening of the epidermis was clearly evident in all the sclerotic lesions examined.

The fibrous capsule around mammary implants: An investigation

Physiopathology of the contracture of the fibrous wall around breast implants is reviewed. In the fine structure of the capsule, the authors have found collagen fibers in fibroblast cytoplasm, a developed Golgi complex, and rough endoplasmic reticulum, which has been unrelated so far. Some fibroblasts resemble those described by Gabbiani et al., but it cannot be concluded that the contracture depends on these fibroblasts. All findings available are discussed, and therapeutic measures based on these findings are proposed.

Inhibitory effects of glucocorticoids on collagen synthesis by mouse sponge granulomas and granuloma fibroblasts in culture

The basis for the glucocorticoid-mediated decrease in tissue collagen was studied in mouse granulomas and in primary granuloma fibroblast cultures. Injection of mice for 12 days with dexamethasone (0.35 mg/kg body weight) resulted in a 50--70% inhibition of collagen synthesis and accumulation in polyvinyl sponge-induced granulomas whereas total protein synthesis was inhibited by only about 25%. The decreased collagen content of the granuloma was accounted for by both a reduced fibroblast number and diminished synthesis per cell. Growth rates, total protein synthesis and collagen synthesis were the same in granuloma fibroblast cultures derived from control or steroid-treated mice. However, addition of 3.10(-7) M hydrocortisone to the culture medium caused a 30--50% inhibition of both collagen and non-collagen protein synthesis in firbroblasts from either source. These inhibitory effects were dose- and time-dependent with a lag time of 12--24 h. Prolyl hydroxylase activity was reduced both in sponge granulomas from glucocorticoid-treated mice and in hydrocortisone-treated fibroblast cultures. However, protein synthesis was inhibited to the same extent as the inhibition of prolyl hydroxylase activity and there was no effect on peptidyl prolyl hydroxylation. These results indicate that the glucocorticoid-induced reduction of collagen synthesis and accumulation observed in mouse granulomas and primary granuloma fibroblast cultures is not specific for this protein. Furthermore, glucocorticoid-induced inhibition of collagen synthesis cannot be attributed to underhydroxylation of collagen prolyl residues.

Collagen polymorphism in pathologic human scars

The collagen type composition of normal and pathologic scars was examined in comparison with normal skin from the same individual. Particular care was taken to separate scar tissue from adjacent normal dermis. After urea extraction, the tissue specimens were cleaved with cyanogen bromide. The presence of the dermal collagen types I and III was deduced from the electrophoretic distribution patterns of the CNBr peptides in 12% SDS-polyacrylamide gels. The intensity of the type III specific peptide bands correlates with the type III content of the samples. Using this method, the presence of both type I and III collagen can be proved in normal as well as pathologic scars. The type III content in older normal scars is slightly increased, whereas the type III content of pathologic scars is significantly increased in comparison with the type III content of normal skin. The electrophoretic CNBr peptide distribution pattern of pathologic scar tissue is almost the same as that of fetal skin. Both are clearly different from the peptide pattern of normal adult skin.

Cyclophosphamide effect on collagen metabolism in granulation tissue, skin, and aorta of rats

Granulation tissue was produced in rats by subcutaneous implantation of viscose cellulose sponges. Cyclophosphamide 10 mg/kg was given daily intraperitoneally to 15 rats from the day of sponge implantation. Fifteen rats served as pair-fed controls, and 15 rats served as non-starved controls. After 14 days of treatment the animals were decapitated. Groups of 3 rats were given 50 muci 14C-proline intraperitoneally 1, 3, 6, 12, or 24 hours before death. The aorta, skin, and granulation tissue were examined. Cyclophosphamide caused no effect on collagen of the aorta, while in skin, the only detectable effect was a decrease in 14C-OH-proline biosynthesis. In granulation tissue, cyclophosphamide caused a fall in the dry weight, a decrease in 14C-proline uptake and 14C-OH-proline synthesis, as well as an increase in the alpha-amino nitrogen to OH-proline ratio in purified collagen. These results indicate that cyclophosphamide inhibits the synthesis of proteins, including collagen, and inhibits the hydroxylation of proline in collagen. No effect of cyclophosphamide could be detected on the amount of salt soluble OH-proline or on collagen cross-linking. The registered effects of cyclophosphamide on granulation tissue is probably of importance with regard to the anti-inflammatory action of cyclophosphamide. This action as well as the tissue differences in the sensitivity of cyclophosphamide may be of relevance to the clinical application of cytostatics in rheumatological diseases.

Biochemical characteristics and biological significance of the genetically-distinct collagens

In recent years it has become evident that genetic polymorphism is dramatically expressed in the structural protein, collagen. Current information on the biochemical properties, biosynthesis, and tissue distribution of Type I, II, and III collagens is summarized with special reference to possible unique functional roles fulfilled by each of these collagens.

Presence of type III collagen in guinea-pig dermal scar

Guinea-pig dermal scar was shown to contain type III collagen, and, from densitometric analysis of gel electrophoretograms, it was shown to have a higher concentration than the surrounding dermis. This finding is consistent with the 'embryonic' nature of newly formed dermal wound tissue, reflected in increased hydroxylation of collagen lysine and the presence of dihydroxylysinonorleucine (after reduction) as the major cross-link.