Collagen polymorphism in pathologic human scars

A Preliminary Report of the Biochemical and Clinical Effects of 1,4-Diaminobutane on Prevention of Human Hypertrophic Scars

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Summary:

Objective evidence for the role of inhibition of collagen cross-linking in human scar using a nontoxic topical inhibitor, 1,4-diaminobutane (1,4 DAB), in patients with scars at risk for hypertrophic scar formation is presented. The authors used a concentration of 1,4 DAB of 0.8% (weight/volume) in a cream base similar to Glaxal Base. Application was once per day at night. The control was treated with cream base alone. In treatment phase studies at 2 months, tissue biopsies were performed and used to determine a therapeutic effect biochemically in paired scars harvested chosen with typical hypertrophic scars at two major treatment centers. Tissue transglutaminase activity revealed a significant reduction of the ε-(γ-glutamyl)lysine cross-links in the treated scars: 7.96 ± 1.51 pmol/µmol amino acid versus 14.78 ± 3.52 pmol/µmol amino acid. A subset of paired scars (n = 15) was also analyzed for soluble procollagen type III amino propeptide. The effect was a significant increase in procollagen type III amino propeptide in the scars treated with 1,4 DAB compared with sham-treated scars: 47.75 ± 4.6 µg/mg wet weight versus 39.08 ± 6.02 µg/mg wet weight, respectively. Levels of tissue 1,4 DAB was found to be twice as high in the presence of the active cream versus in the tissue of the control group. In subsequent prophylaxis studies, the authors treated 44 breast reduction patients prospectively with active cream to one or the other side in a double-blind randomized fashion. Hardness (in grams) measured using a Rex Durometer at 6 and 12 weeks postoperatively along with photographs were analyzed. The mean value ± SD of 24.98 ± 1.2 g on the active side versus 31.76 ± 1.1 g on the sham side was significantly different (p < 0.05). The patient scale scores of the Patient and Observer Scar Assessment Scale were also requested by survey in a responding 27-patient subgroup at a minimum 1 year postoperatively, and the differences between the two sides were found to be statistically significant, where the mean on the active side was 14.07 ± 1.34 and the mean on the sham side was 21.41 ± 1 (p < 0.05). The results are evidence to support the use of this agent in prevention of hypertrophic scars.

CLINICAL QUESTION/LEVEL OF EVIDENCE:

Therapeutic, II.

Pectoralis Major (Breast) Muscle Extracellular Matrix Fibrillar Collagen Modifications Associated With the Wooden Breast Fibrotic Myopathy in Broilers

The poultry industry has placed significant emphasis on the selection of meat-type broilers for increased body weight, increased meat yield especially the pectoralis major (breast) muscle, decreased time to processing, and improved feed conversion_. Although significant improvements have occurred in fast-growing meat-type broilers, myopathies affecting meat quality especially in the pectoralis major muscle have occurred. Many of the broiler breast muscle myopathies are caused by inflammation leading to the necrosis of existing muscle fibers and resulting in replacement of the muscle fibers with extracellular matrix proteins especially fibrillar collagens, fibrosis. This review explores how the fibrotic deposition and organization of extracellular matrix proteins especially the fibrillar collagens, Types I and III, affects the phenotype of the Wooden Breast myopathy, functional properties of the pectoralis major muscle, and meat quality.

The Effect of the Wooden Breast Fibrotic Myopathy in Broilers on Fibrillar Collagen Organization and Decorin-Collagen Binding

The wooden breast myopathy is identified by the palpation of a rigid pectoralis major muscle and results in myofiber necrosis and fibrosis in fast-growing, meat-type broilers. The fibrosis in wooden breast-affected muscle is characterized by the replacement of myofibers with extracellular matrix proteins, especially fibril-forming collagens. Studies have shown differences in collagen organization in fast-growing broiler lines, with tightly packed and highly aligned collagen organizations having a higher phenotypic incidence of wooden breast. The objective of the current study was to analyze collagen fibril organization further in two fast-growing broiler lines (Lines A and B) with incidence of wooden breast compared with a slower growing broiler Line C with no phenotypically detectable wooden breast. The small leucine-rich proteoglycan decorin was also studied for its interaction with collagen by immunogold detection. Decorin binds to fibrillar collagens and organizes their alignment and crosslinking, both of which will affect collagen functional properties. Key findings from the study showed that collagen shifts to larger diameter collagen fibril bundles with the wooden breast myopathy. Specifically, broilers affected with wooden breast from Line A had a more dramatic shift toward larger collagen fibril bundles compared with those affected from Line B. Wooden breast-affected Line A had collagen fibril bundles up to 8.4 µm, whereas Line B maximum size was 5.1 µm. Although decorin-collagen binding was not different overall in the wooden breast myopathy or broiler line, for small-diameter collagen fibril bundles, wooden breast-affected Line A had more decorin-collagen binding than wooden breast-affected Line B. Taken together, these data provide further evidence that multiple fibrotic myopathies are likely in fast-growing meat-type broilers.

The Superficial Dermis May Initiate Keloid Formation: Histological Analysis of the Keloid Dermis at Different Depths

Several studies have reported on certain aspects of the characteristics of different sites within a keloid lesion, but detailed studies on the keloid dermis at different depths within a keloid lesion are scarce. The aim of this study was to investigate the histology of the keloid dermis at different depths. This study included 19 keloid tissue samples that were collected from 19 patients and 19 normal skin samples, which were harvested from subjects without keloids or hypertrophic scar. Samples were studied by light microscopy using routine hematoxylin and eosin histochemical staining, and immunohistochemistry to detect CD20-positive B-lymphocytes and CD3-positive T-lymphocytes. Sirius Red histochemical staining was used to determine the type of collagen in keloid tissue and normal skin samples. The migratory properties of fibroblasts within the keloid dermis at different depths was compared, using an in vitro migration assay. The findings of this study showed that although the papillary and reticular dermis could be clearly distinguished in normal skin, three tissue layers were identified in the keloid dermis. The superficial dermis of keloid was characterized by active fibroblasts and lymphocytes; the middle dermis contained dense extracellular matrix (ECM) with large numbers fibroblasts, and the deep dermis was poorly cellular and characterized by hyalinized collagen bundles. In the keloid samples, from the superficial to the deep dermis, type I collagen increased and type III collagen decreased, and fibroblasts from the superficial dermis of the keloid were found to migrate more rapidly. In conclusion, the findings of this study showed that different depths within the keloid dermis displayed different biological features. The superficial dermis may initiate keloid formation, in which layer intralesional injection of pharmaceuticals and other treatments should be performed for keloid.

Structural Insights into the Glycine Pair Motifs in Type III Collagen

Human type III collagen has been suggested to play vital roles in a series of pathophysiological conditions. Sequence analysis among major fibril-forming collagens (types I, II, and III) revealed that Gly-Gly pairs are a distinct sequence feature in type III collagen. This motif occurs more than five times as often in type III compared to type I and II collagens. We used an integrated computational modeling and biophysical approach to analyze the glycine pair motifs to understand how they govern the structure of type III collagen at the molecular level. Triple helical peptides to model the regions of type III collagen containing GG motifs were used to analyze structural and thermodynamic effects of GG incorporation into the collagen sequence. We found that when amino acids adjacent to a GG motif are charged, the collagen adopts a more flexible, random conformation. The GG motif led to altered hydrogen bond patterns and decreased global melting temperatures of the triple helical peptides. The local entropic destabilization effect of the glycine pair helps explain the difference in the flexibility between types I and III collagen fibrils. This finding reveals potential physiological roles of type III collagen in regulating the mechanical properties of collagen fibrils and may enable the design of future collagen-like materials with tunable mechanical properties.

Neuroinflammatory Mechanisms of Connective Tissue Fibrosis: Targeting Neurogenic and Mast Cell Contributions

Significance: The pathogenesis of fibrogenic wound and connective tissue healing is complex and incompletely understood. Common observations across a vast array of human and animal models of fibroproliferative conditions suggest neuroinflammatory mechanisms are important upstream fibrogenic events. Recent Advances: As detailed in this review, mast cell hyperplasia is a common observation in fibrotic tissue. Recent investigations in human and preclinical models of hypertrophic wound healing and post-traumatic joint fibrosis provides evidence that fibrogenesis is governed by a maladaptive neuropeptide-mast cell-myofibroblast signaling pathway. Critical Issues: The blockade and manipulation of these factors is providing promising evidence that if timed correctly, the fibrogenic process can be appropriately regulated. Clinically, abnormal fibrogenic healing responses are not ubiquitous to all patients and the identification of those at-risk remains an area of priority. Future Directions: Ultimately, an integrated appreciation of the common pathobiology shared by many fibrogenic connective tissue conditions may provide a scientific framework to facilitate the development of novel antifibrotic prevention and treatment strategies.

Pharmacological treatment for keloids

INTRODUCTION

Keloids are fibroproliferative disorders that are characterized by histological accumulation of collagens and fibroblasts, refractory clinical symptoms such as itching, topical invasiveness, and frequent postsurgical recurrence. At present, to treat or prevent keloids, new drugs are currently being designed and the pharmaceutical indications of known drugs are being expanded.

AREAS COVERED

The current pharmacological interventions for keloids are mainly described on the basis of the various hypotheses on keloid etiology and the keloid ingredients that are targeted. These interventions include angiotension-converting enzyme inhibitors and calcium-channel blockers (based on hypertension hypothesis), selective estrogen receptor modulator (based on endocrinological hypothesis), vitamins and essential fatty acids (based on immunonutritional hypothesis), and transglutaminase inhibitor (based on metabolic hypothesis). Drugs that directly target the reduction or destruction of the major extracellular matrix or cellular constituents of keloids are also included. Besides, drugs that indirectly modulate the biochemical microenvironment are described. These include growth factors, immunomodulators, and anti-inflammation and anti-allergy drugs.

EXPERT OPINION

Due to the unclear etiology of keloids and the lack of animal models, efficient, reliable, and specific pharmaceutical interventions for keloids continue to be lacking. The reliability of current data and clinical observations must be strengthened by large-scale, randomized, controlled clinical trials.

Keloid pathogenesis via Drosophila similar to mothers against decapentaplegic (SMAD) signaling in a primary epithelial-mesenchymal in vitro model treated with biomedical-grade chitosan porous skin regenerating template

The effects of locally produced chitosan (CPSRT-NC-bicarbonate) in the intervention of keloid pathogenesis were investigated in vitro. A human keratinocyte-fibroblast co-culture model was established to investigate the protein levels of human collagen type-I, III and V in a western blotting analysis, the secreted transforming growth factor-β1 (TGF-β1) in an enzyme-linked immunosorbent assay (ELISA) and the mRNA levels of TGF-β1's intracellular signaling molecules (SMAD2, 3, 4 and 7) in a real-time PCR analysis. Keratinocyte-fibroblast co-cultures were maintained in DKSFM:DMEM:F12 (2:2:1) medium. Collagen type-I was found to be the dominant form in primary normal human dermal fibroblast (pNHDF) co-cultures, whereas collagen type-III was more abundant in primary keloid-derived human dermal fibroblast (pKHDF) co-cultures. Collagen type-V was present as a minor component in the skin. TGF-β1, SMAD2 and SMAD4 were expressed more in the pKHDF than the pNHDF co-cultures. Co-cultures with normal keratinocytes suppressed collagen type-III, SMAD2, SMAD4 and TGF-β1 expressions and CPSRT-NC-bicarbonate enhanced this effect. In conclusion, the CPSRT-NC-bicarbonate in association with normal-derived keratinocytes demonstrated an ability to reduce TGF-β1, SMAD2 and SMAD4 expressions in keloid-derived fibroblast cultures, which may be useful in keloid intervention.

Quantitative multispectral imaging of Herovici's polychrome for the assessment of collagen content and tissue remodelling

Bioprosthetic devices, constructed from a variety of materials, are routinely implanted in a variety of anatomical locations. Essential to their success is the formation of a non-destructive interface with the host tissue and appropriate tissue remodelling. Traditionally, the main method of assessing the host-material interface has been qualitative histological evaluation, using pattern recognition and comparative assessment to identify changes in the normal tissue architecture that are characteristic of scar tissue. In the present study, the recently developed technique of multispectral imaging was used to revisit a little-described histological stain, Herovici's polychrome, which is capable of distinguishing between types I and III collagen. Combined, these techniques allowed quantification of collagen content and distribution of collagen types within a tissue sample. Samples of rat tail and human scar tissue were used to optimize the staining, while comparison with immunolabelled samples was used to develop a reproducible quantification system, based on the specific colour profiles for types I and III collagen. Finally the remodelling of rat abdominal wall defects repaired with crosslinked or non-crosslinked extracellular matrix scaffolds derived from porcine urinary bladder was assessed with this technique. Compared to standard histological assessment, the combination of multispectral imaging and Herovici's polychrome staining presents a quick, simple, reliable technique that can provide accurate quantification of tissue remodelling and specifically identify the expression and distribution of types I and III collagen.

Hypertrophic versus non hypertrophic scars compared by immunohistochemistry and laser confocal microscopy: type I and III collagens

Although dermal collagens appear increased in hypertrophic scars, this has not been tested in tissue samples using objective methods. We compared the expression of types I and III collagen in hypertrophic and non hypertrophic scars at 6-12 and 18-24 months after burn using a quantitative method. Among 17 patients with extensive burns, 3 patients had acute scars, 8 had hypertrophic or non hypertrophic scars at 6-12 months after burn and 6 had hypertrophic or non hypertrophic scars at 18-24 months after burn. After clinical assessment of scars using the Vancouver scale, immunohistochemistry for types I and III collagens was performed. Images were captured with a laser scanning confocal microscope and the relative amounts of types I and III collagens were determined in superficial and deep dermis. The effects of time and scar type were assessed using two-way analysis of variance (ANOVA) and Tukey's test. Collagen III scar/normal ratios were higher in hypertrophic scars at both time points (P = 0.05). There were no differences in collagen I scar/normal ratios. Large variation was observed in scars during the acute phase regarding the expression of collagens. Easily accessed by immunohistochemistry and confocal microscopy, type III collagen deposition may help in determining scar phenotype, differentiating hypertrophic and non hypertrophic scars.

A Randomized, Controlled Trial to Determine the Efficacy of Paper Tape in Preventing Hypertrophic Scar Formation in Surgical Incisions that Traverse Langer??s Skin Tension Lines

BACKGROUND

How a scar is managed postoperatively influences its cosmetic outcome. After suture removal, scars are susceptible to skin tension, which may be the trigger for hypertrophic scarring. Paper tape to support the scar may reduce multidirectional forces and prevent hypertrophic scarring.

METHODS

Seventy patients who had undergone cesarean section at the Royal Brisbane and Women's Hospital were randomized to treatment and control groups. Patients in the control group received no postoperative intervention. Patients in the treatment group applied paper tape to their scars for 12 weeks. Scars were assessed at 6 weeks, 12 weeks, and 6 months after surgery using ultrasound to measure intradermal scar volume. Scars were also assessed using the International Clinical Recommendations.

RESULTS

Paper tape significantly decreased scar volume by a mean of 0.16 cm3, (95 percent confidence interval, 0.00 to 0.29 cm3). At 12 weeks after surgery, 41 percent of the control group developed hypertrophic scars compared with none in the treatment group (exact test, p = 0.003). In the treatment group, one patient developed a hypertrophic scar and four developed stretched scars only after the tape was removed. The odds of developing a hypertrophic scar were 13.6 times greater in the control than in the treatment group (95 percent confidence interval, 3.6 to 66.9). Of the 70 patients randomized, 39 completed the study. Four patients in the treatment group developed a localized red rash beneath the tape. These reactions were minor and transient and resolved without medical intervention.

CONCLUSIONS

The development of hypertrophic and stretched scars in the treatment group only after the tape was removed suggests that tension acting on a scar is the trigger for hypertrophic scarring. Paper tape is likely to be an effective modality for the prevention of hypertrophic scarring through its ability to eliminate scar tension.

Hypertrophic Scar Cells Fail to Undergo a Form of Apoptosis Specific to Contractile Collagen—The Role of Tissue Transglutaminase

Failure of apoptosis has been postulated to cause the hypercellularity and thus excess scar-tissue formation of hypertrophic scars (HTS). Here, we have examined the susceptibility of fibroblasts derived from normal or HTS to apoptosis induced during collagen-gel contraction, a wound-healing model. Normal scar (NS) fibroblasts underwent significant apoptosis (>40% total) in contractile collagen, whereas apoptosis was not detected in HTS cells. This inability was specific to apoptosis induced by contractile collagen because apoptosis could be induced using diverse modalities. Since chronic fibrotic tissue is known to be excessively cross-linked, we next examined whether collagen matrix that had been conditioned by HTS fibroblasts became refractory to enzymatic breakdown and indeed, found that it is resistant to breakdown by both collagenase D and matrix metalloproteinase-2. Newly formed extracellular matrix is stabilized by the enzyme, tissue transglutaminase, which we demonstrated to be overexpressed by HTS fibroblasts in vivo and in vitro. Reducing tissue transglutaminase activity in collagen gels containing HTS fibroblasts permitted induction of apoptosis on gel contraction, whereas increasing enzymic activity in NS cell-containing gels completely abrogated collagen-contraction-induced-apoptosis. Together, these observations show that HTS fibroblasts exhibit resistance to a specific form of apoptosis elicited by contraction of collagen gels, and that this phenomenon is dependent on excess activity of cell surface tissue transglutaminase.

Effect of Mederma on hypertrophic scarring in the rabbit ear model

Currently accepted conservative treatments of hypertrophic scars are limited to steroid injections, radiation therapy, and silicone occlusive therapy. However, the use of Mederma for these problematic lesions has become quite prevalent in the clinical setting. Little scientific evidence exists to support the efficacy of this product in reducing hypertrophic scars. The aim of this study was to study the effects of Mederma on hypertrophic scars in the rabbit hypertrophic scar model, allowing the histologic quantification of scar elevation, dermal collagen organization, vascularity, and inflammation and the gross examination of scar erythema. Full-thickness wounds down to cartilage, four per ear, were created in four New Zealand White rabbits, for a total of 32 scars. Twenty-eight days after the initial wounding, the hypertrophic scars were photographed, and treatment of half of the scars on each ear was begun with Mederma three times per day for a total of 4 weeks. The untreated scars served as control scars and were left exposed to air. After 4 weeks of treatment, the scars were once again photographed. The rabbits were then killed, and the scars were analyzed histologically. The pretreatment and posttreatment photographs were compared by using computer quantification of magenta, yellow, and cyan expression within the scars. Histologic analysis demonstrated no significant reduction in scar hypertrophy or scar elevation index. However, a significant improvement in dermal collagen organization was noted on comparing Mederma-treated scars with untreated control scars (p < 0.05). No significant difference in dermal vascularity or inflammation was noted. Computer analysis of the scar photographs demonstrated no significant reduction in scar erythema with Mederma treatment. The active product in Mederma, allium cepa, has as its derivative quercetin, a bioflavonoid noted for its antiproliferative effects on both normal and malignant cells, and its antihistamine release effects. These properties could theoretically prove beneficial in reversing the inflammatory and proliferative responses noted in hypertrophic scars. Despite the authors' inability to demonstrate a reduction in scar hypertrophy, the improvement in collagen organization noted in the Mederma-treated scars suggests it may have an effect on the pathophysiology of hypertrophic scar formation.

Altered posttranslational modifications of collagen in keloid

Keloid is a tissue with an excessive accumulation of collagen. In this study, we have partially characterized post-translational modifications of type I collagen in human keloid in order to pursue their potential involvement in this pathology. The levels of lysyl hydroxylation of the helical portions of alpha 1 and alpha 2 chains of type I collagen in keloid were significantly higher than those of normal, while the levels of prolyl hydroxylation were identical between these two groups. The contents of the major reducible cross-links in dermal collagen, dehydro-hydroxylysinonorleucine and dehydro-histidinohydroxymero-desmosine, were both significantly higher in keloids (up to sixfold) than those of normal. In addition, significant amounts of hydroxylysine-aldehyde derived cross-links that are characteristic of skeletal tissue collagens, dehydro-dihydroxylysinonorleucine (about 0.3 mole/mole of collagen) and pyridinoline (about 0.1 mole/mole of collagen), were found in keloids. These results indicate that keloid-forming cells are phenotypically different from those in normal dermis and that the collagen produced is highly cross-linked. The increased cross-linking provides the fibrils with more stability that may result in an accumulation of collagen.

Adjunct therapies to surgical management of keloids

BACKGROUND

The literature describing surgical treatments, with or without supplementary nonsurgical treatments for keloids, offers a confusing picture of widely variable "success" rates, recurrence rates, patient populations, and follow-up periods.

OBJECTIVE

A review of the surgical treatment of keloids with emphasis on surgery combined with nonsurgical therapies is presented.

RESULTS

Surgery alone leads to recurrence rates ranging from 45 to 100%. When surgery is combined with intradermal corticosteroids the recurrence rate in the majority of studies falls below 50%. Surgery combined with button compression therapy on earlobes led to no recurrences. External radiation following excision, often combined with other therapies, has been associated with recurrence rates of less than 10%. Various lasers have been used in the treatment of keloids with great variability in the recurrence rate but in general result in similar recurrence rates as conventional surgery. As with cryodestruction, laser ablation recurrence rates often are improved when combined with other treatments. Inferon-alpha 2b injected after keloid excision demonstrated, in a small series of patients an 8% recurrence rate.

CONCLUSION

Presently, it appears that a combined therapeutic approach offers the most propitious possibility for preventing keloid recurrence.

Topical putrescine (Fibrostat) in treatment of hypertrophic scars: phase II study

Previous studies indicated that tissue transglutaminase plays a role in the cross-linking of type III procollagen in wound matrices and that this may be inhibited by 50 mM putrescine in vitro. For this reason, the clinical effect of 50 mM putrescine in a eutectic vehicle (Fibrostat) was studied in this phase II double-blind crossover study in 43 patients. Twenty of the patients had had recent surgery and were studied for product safety rather than efficacy. No toxic effects were observed in this group of patients, and only 1 of the 23 unoperated patients had a rash during treatment. The observed effect of Fibrostat versus sham treatment of 1 month's duration in active hypertrophic scar was a significant improvement of hypertrophy in 23 patients during the Fibrostat treatment arm, regardless of the order in which treatment was received. It is suggested that Fibrostat is a safe therapeutic agent for treatment of hypertrophic scar. Clinical examples to illustrate its use are given.

Collagen biosynthesis in human oral submucous fibrosis fibroblast cultures

To investigate the mechanism of collagen accumulation in oral submucous fibrosis (OSF) tissues, we examined the biosynthesis of collagen in fibroblast cultures established from OSF lesions. Fibroblasts obtained from four of ten OSF specimens showed more than a 1.5-fold increase in the production of collagens compared with fibroblasts from age-, sex-, and passage-matched normal controls (p < 0.05). When the relative amounts of collagen synthesis were estimated by SDS polyacrylamide gel electrophoresis, it was found that both OSF and control cells produced about 85% type I collagen and 15% type III collagen. The ratio of alpha 1(I) to alpha 2(I) chains was about 3:1 in OSF cells instead of the 2:1 expected for type I collagen. The excess alpha 1(I) chains could mean that collagen type I trimer was synthesized by the fibroblasts. These findings suggest that collagen overproduction and a reduced degradation of the structure-stable collagen type I trimer synthesized by OSF fibroblasts might contribute to the accumulation of collagen in OSF lesions in vivo. The mechanism(s) of increased procollagen production were analyzed by Northern blot, slot blot, and Southern blot. The OSF fibroblast strains with elevated collagen production also contained higher-than-normal levels of procollagen mRNA, and the ratios of alpha 1(I), alpha 2(I), and alpha 1(III) procollagen mRNAs were compatible with the results of corresponding procollagen alpha chains. The gene copy number of pro alpha 2(I) collagen gene in OSF fibroblasts was about 1.05. No gene amplification was found. These results indicate that expression of these procollagen genes in cultured fibroblasts is regulated at the transcriptional level.

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.

Alteration of collagen composition and cross-linking in keloid tissues

Collagen composition and cross-linking in human keloid and normal skin tissues were analyzed biochemically. CNBr peptides were separated by 2-dimensional (2-D) mapping and high performance liquid chromatography (HPLC). The amounts of type I and type III collagen was quantified by 2-D scanning densitometry of fluorographs of 2-D maps derived from samples radioactively labelled in vitro by [3H]-NaBH4 in dimethylformamide. Keloid tissues contained 31.6 +/- 2.2 percent type III collagen as compared to 21.4 +/- 2.7 percent type III present in normal human skin dermis. HPLC profiles of CNBr peptides showed that approximately 5 percent of the high molecular weight material in keloids is mercaptoethanol reducible, compared to insignificant amounts in normal skin. 2-D maps derived from CNBr peptides of keloid collagen demonstrated thiol reduction sensitive alpha 1(III)-CB9 dimer as well as 24,000- and 32,000-dalton CNBr peptides, which were not mercaptoethanol reduction sensitive in normal skin due to cross-linking via the lysyl oxidase pathway. Also, a group of 20,000- to 25,000-dalton CNBr peptides, in the alpha 1(I)-CB6 cross-linking region were prominent in keloid tissues.

Selectively enhanced procollagen gene expression in sclerosing (morphea-like) basal cell carcinoma as reflected by elevated pro alpha 1(I) and pro alpha 1(III) procollagen messenger RNA steady-state levels

Sclerosing or morphea-like variant of basal cell carcinoma (BCC) is characterized by an extensive connective tissue stroma, and histopathology has suggested that the extracellular matrix is largely composed of collagen. In addition, fibronectin deposition has been proposed to modulate tumor growth in BCC. In this study, we examined the expression of genes coding for type I, III, and IV procollagens, as well as for fibronectin, in tissue from 10 patients with sclerosing BCC. For comparison, tissues from 5 patients with nodular BCC and 4 controls were examined. Total RNA was isolated by CsCl density gradient centrifugation, and messenger RNA (mRNA) steady-state levels were determined by slot-blot hybridizations with human sequence specific complementary DNAs (cDNAs). The abundance of type I procollagen mRNA in sclerosing BCC tissue was increased to 233.6 +/- 36.7% of the controls (mean +/- SEM). The corresponding value for type III procollagen mRNA in sclerosing BCC was 281.8 +/- 54.8% of the controls. Consequently, the steady-state ratio of type I/III procollagen mRNAs in sclerosing BCCs (5.0 +/- 1.2; mean +/- SD) was within the control range. Thus, there is a coordinate increase in type I and type III procollagen mRNA levels in sclerosing BCC. In contrast, the values for type I and type III procollagen mRNAs in nodular BCC were not different from the controls. In addition, type IV procollagen and fibronectin mRNA levels were not different from the controls either in sclerosing or nodular BCCs, attesting to the selectivity of the increase in type I and III procollagen mRNA levels in sclerosing BCC. These observations may relate to the excessive deposition of the extracellular matrix stroma surrounding the tumor cells in sclerosing BCC.

Characterization of rabbit stromal fibroblasts derived from red and yellow bone marrow

Rabbit stromal fibroblasts subcultured from red and yellow bone marrow and implanted beneath the renal capsule form ossicles the hemic cellularity of which mirrors the cellularity of the marrow used for culture. Although the cultured red and yellow marrow cells are similar in fine-structural appearance, they differ strikingly in enzymatic content of alpha-naphthylbutyrate esterase, which is abundant only in the cells derived from yellow marrow. Other observers (20, 21) have proposed that stromal fibroblasts are preadipocytes, and this data suggests that those derived from yellow marrow have the phenotype of more differentiated adipocytes. On the other hand, fibroblasts derived from red and yellow bone marrow show no differences in their profiles of procollagen synthesis. Both types of fibroblasts secrete type III procollagen as the major species, with a I/III ratio of 1:3; in contrast, rabbit dermal fibroblasts have a prominent peak of type I procollagen. The similarity of stromal cells derived from red and yellow bone marrow in procollagen synthesis suggests that the collagen part of the extracellular matrix is not the only basis for their intrinsic difference in capacity for hematopoiesis.

Selective decrease of type I collagen synthesis in Fraser mice skin

Quantification and biosynthesis of type I and type III collagens were determined in skin of control and Fraser mice (CatFraser mutation), which exhibit a genetically determined cataract. Skin organ cultures were labelled with [3H]proline. Pepsin-solubilized collagens were studied using three different approaches: (a) differential salt precipitation at neutral pH, followed by SDS-polyacrylamide gel electrophoresis; (b) differential salt precipitation at acid pH followed by SDS-polyacrylamide gel electrophoresis. (c) CNBr peptide analysis. These methods gave consistent and reproducible results, indicating a selective decrease of type I collagen in Fraser mouse skin as compared to control mouse skin. Metabolic labelling of skin organ cultures showed a decreased specific radioactivity of hydroxy[3H]proline in type I collagen of Fraser mouse skin. The concordant results of these experiments suggest a genetically determined alteration of interstitial collagen metabolism in the Fraser mutation apparently specifically concerning the expression of type I collagen gene(s).

Fine structural alterations in chronic Achilles paratenonitis in athletes

The fine structural alterations in chronic Achilles paratenonitis were studied in tissue samples obtained from 14 athletes, who were operated on for this complaint and from 3 patients without any history of this disease. In the chronically inflamed paratendineal tissue mainly two types of cells were identified: classic fibroblasts with a smooth and rough endoplasmic reticulum and only a few mitochondria and lysosomes and myofibroblast-like cells with cytoplasmic microfilaments 5-6 nm in diameter, a rough endoplasmic reticulum, some mitochondrias and free ribosomes. These cells represented 19% of 471 studied non-inflammatory cells. In the extracellular space there was an increased amount of fibrils regarded as either type I or type III collagen as sign of tissue repair. Especially around the myofibroblastic cells a fine granular ground substance was found. The amount of ground substance was as a rule increased in pericellular space. Due to the capacity of contraction in healing tissue the myofibroblasts apparently have a role in the clinical symptoms of chronic Achilles paratenonitis.

Biochemical composition of the connective tissue in keloids and analysis of collagen metabolism in keloid fibroblast cultures

Keloids are histologically characterized by an abundance of the extracellular matrix of connective tissue. In the present study, we examined the connective tissue composition of keloids, and analyzed the details of collagen metabolism utilizing fibroblast cultures established from keloid tissue. Quantitative connective tissue analyses indicated that collagen was the predominant extracellular matrix component in keloids. The ratio of genetically distinct collagens type I/III was significantly increased, as compared to normal human skin. Collagen biosynthesis was measured in fibroblast cultures by the formation of radioactive hydroxyproline: 5 of 9 keloid cell cultures studied demonstrated increased procollagen production in comparison to age-, sex-, and passage-matched control skin fibroblast lines, while the remaining 4 cell lines were within the control range. Keloid fibroblast cultures which were high collagen producers also demonstrated elevated prolyl hydroxylase activity. The mechanisms of increased procollagen production in fibroblast cultures were first examined by assaying the abundance of type I procollagen-specific mRNA utilizing dot blot hybridizations with a pro alpha 2(I)-chain-specific cDNA. The type I procollagen mRNA levels were significantly increased in 4 keloid fibroblast lines, and a good correlation between the mRNA levels and the rate of procollagen production in the same cultures was noted. These observations suggest regulation of the collagen gene expression on the transcriptional level. The catabolic pathway of collagen metabolism in fibroblast cultures was examined by determining the degradation of newly synthesized procollagen polypeptides through assay of radioactive hydroxyproline in small-molecular-weight peptide fragments. In 3 keloid cell cultures, the degradation of newly synthesized collagen polypeptides was below the range of normal controls. These findings suggest that a reduced degradation of newly synthesized polypeptides might contribute to the accumulation of procollagen in some keloid fibroblast cultures. The results of this study suggest two possible mechanisms for deposition of collagen in keloid lesions in vivo: first, the growth of the lesions may result from a localized loss of control of the extracellular matrix production by fibroblasts; secondly, reduced degradation of the newly synthesized procollagen polypeptides may contribute to collagen deposition in some keloids.

Characterisation of collagen from normal and scoliotic human spinal ligament

Acid-soluble and pepsin-soluble collagens have been isolated from spinal ligaments of normal and scoliotic individuals. Polyacrylamide gel electrophoresis of native and cyanogen bromide-treated collagens, and amino acid analysis, showed that the ligament collagen is almost all of the Type I variety with only trace amounts of Type III present. There was no evidence for abnormal ratios of collagen alpha-chains, or underhydroxylation of proline and lysine in the scoliotic ligament. These results indicate that collagen biochemistry is normal with respect to type, post-translational modification and cross-linking in spinal ligaments of patients with idiopathic scoliosis. Elastin and proteoglycan were only minor components of the ligaments. The nature of the non-collagenous part of the ligament is unknown, although it contains some proteins with a hydrophobic nature.

Anomalous electrophoretic behavior of a cyanogen bromide peptide from type III collagen

The relationship between relative mobility on sodium dodecyl sulfate-polyacrylamide gels and the logarithm of molecular weight was linear for peptides derived by CNBr cleavage from purified collagen chains. One striking exception was found: when the CNBr peptide alpha 1(III)CB-8 was subjected to electrophoresis on a polyacrylamide slab gel calibrated with other peptides derived from the type III collagen chain, its relative mobility corresponded to a molecular weight of approximately 8,000. On a gel calibrated with globular proteins, its apparent molecular weight was 12,000. Its actual molecular weight, as determined by gel filtration and by amino acid analysis, is approximately 12,000. The dodecyl sulfate-protein binding ratio for this peptide did not differ from that of other collagenous peptides or globular proteins. Free electrophoretic mobilities and retardation coefficients were determined for selected collagenous peptides and globular proteins by electrophoresis on tube gels of different concentrations of acrylamide. By these indices, alpha 1(III)CB-8 resembled a globular protein rather than a collagenous peptide. Presumably, some difference in primary structure of this peptide results in conformational changes of its complex with dodecyl sulfate, such that the peptide-dodecyl sulfate complex behaves more like a globular protein than a collagenous peptide on polyacrylamide gels.

Keloids: a review

Keloids are predominantly fibrous tumors which appear as firm, variably pruritic or tender growths near a site of injury. Usually appearing between the ages of 10 and 30, most keloids are located on the upper back, shoulders, earlobes, and anterior portion of the chest. The etiology remains unknown, but the accumulated fibrous tissue is associated with increased cellularity and increased metabolic activity of keloid fibroblasts. Isolated keloid fibroblasts demonstrate normal growth characteristics along with increased collagen and proteoglycan synthesis. Numerous keloid treatments have been attempted, but variable success has followed either single use or combinations of intralesional corticosteroid injection, surgery, pressure devices, radiation, cryosurgery, and systemic chemotherapy.

Extraction and translation of collagen mRNA from fetal calf skin

RNA was extracted from fetal calf skin by two different procedures, using phenol or guanidine hydrochloride. Poly(A)-rich RNA was separated by oligo(dT)-cellulose affinity chromatography and was further fractionated by sucrose density gradient centrifugation. When translated in an optimized wheat germ extract cell-free system, unfractionated guanidine-hydrochloride-extracted poly(A)-rich RNA directed the synthesis of two collagenase-sensitive protein bands, while phenol-extracted poly(A)-rich RNA with a sedimentation coefficient higher than 25 S was the only fraction to direct the same synthesis. On the basis of their electrophoretic mobility on a sodium dodecylsulfate/urea/polyacrylamide gel, these proteins were identified with procollagen alpha 1(I) and procollagen alpha 2. Inhibition of translation by phenol-extracted poly(A)-rich RNA with a sedimentation coefficient lower than 25 S was also observed. Guanidine-hydrochloride-extracted poly(A)-rich RNA from fetal skin directed the synthesis of three distinct collagenase-sensitive proteins in the micrococcal-nuclease-digested rabbit reticulocyte cell-free system; these seemed to correspond to procollagen alpha 1(I), procollagen alpha 2 and procollagen alpha 1 (III).

Nature of collagen in dermatofibrosarcoma protuberans

The nature of collagen from 2 cases of dermatofibrosarcoma protuberans was studied. For this purpose, the tumor tissue was carefully separated from adjacent normal dermis. The collagen types comprised in the tumor were identified by CM-cellulose chromatographic and SDS-gel electrophoretic analysis of the component alpha-chains. Semiquantitative evaluation of the relative type III content was established by separation of the cyanogen bromide peptides on gels of 12% polyacrylamide in SDS. These studies showed that dermatofibrosarcoma protuberans contains alpha 1(I)-, alpha 2-, and alpha 1(III)-chains as well, and corresponding type I- and type III-related CNBr peptides. Comparing the collagen from dermatofibrosarcoma protuberans to that of normal skin, the relatively increased type III content in the case of dermatofibrosarcoma protuberans becomes apparent.