Increased mRNA expression of decorin in the prolapsing posterior leaflet of the mitral valve

To improve our understanding of myxomatous degeneration of the valvar tissue as seen in mitral valve prolapse, we have compared the biosynthetic phenotype of the connective tissue cells in myxomatous segments (n=4) resected during surgery with that of homologous segments of normal valves (n=4) harvested in age-matched organ donors. The steady-state level of mRNA for selected extracellular matrix macromolecules and metalloproteinases was assessed by quantitative (internal standard controlled) reverse transcriptase-polymerase chain reaction (RT-PCR). Among the investigated gene products, the decorin mRNA expression was significantly increased in degenerative valve compared with normal tissue (211+/-48 vs. 100+/-70, p<0.02). The level of fibrillin 2 also tended to be increased (194+/-88 vs. 100+/-81, p=0.08). These results suggest that myxomatous valvar tissue is characterized by an overexpression of mRNA for decorin. Owing to the role of this small leucine-rich proteoglycan in the regulation of fibril assembly and stability, this alteration may account for or is a result of a defective organization of the collagen and elastic fibers in this disease and contribute to the intrinsic distensibility and fragility of the myxomatous tissue.

Primary sarcoma of an abdominal aortic aneurysm

Primary tumors of the aorta are extremely rare and the diagnosis is made most often after surgery or autopsy. Because clinical symptoms of abdominal sarcoma are similar to those of occlusive or aneurysmal disease, aortic sarcomas are frequently mistaken for these lesions. The imaging findings are frequently nonspecific and therefore do not allow a definitive preoperative diagnosis. We report a case of an epithelioid angiosarcoma in the vessel wall of an abdominal aortic aneurysm.

Development of a reconstituted nerve in a three-dimensional collagen gel under tension populated with fibroblasts and Schwann cells

Our aim is to devise an artificially reconstituted nerve segment made of a three-dimensional collagen gel populated with aligned fibroblasts and Schwann cells. Collagen lattices were prepared by mixing concentrated medium, a type I collagen solution and rat Schwann cells (SC), rat neural fibroblasts (nF) or human dermal fibroblasts (dF) and allowed to polymerize at 37 degrees C. In these free-floating lattices, nF and dF retracted the gel more than SC. All cells appeared to be elongated and oriented at random. Rat cells obtained by enzymatic digestion of nerves undergoing wallerian degeneration retracted the gel at a larger extent than cells from intact nerves. Rectangular lattices restrained at each extremity acquired a paraboloid shape upon retraction by neural or dermal F reflecting the mechanical tension developed by these cells on their support. Adult SC alone produced a faint paraboloid even at high cell density while SC associated with nF developed a paraboloid similar to that obtained with nF alone. The mechanical force developed by dermal F and SC in the restrained lattice was measured by strain gauges and found much higher for F than for SC. In restrained lattices, both types of F were elongated and aligned to the long axis of the gel while SC elongated but not necessarily in a parallel fashion. The central portion of a mixed nF-SC collagen restrained lattice produces a flattened cylindric segment made of longitudinally oriented col-lagen fibrils, F and SC, which could represent a promising material for preparation of nerve grafts. An original plastic mould was devised to allow the preparation of cylindrical segments of free or restrained collagen lattices in view of in vitro and in vivo regeneration studies.

Positron emission tomography (PET) evaluation of abdominal aortic aneurysm (AAA)

BACKGROUND

aneurysmal disease is associated with an inflammatory cell infiltrate and enzymatic degradation of the vessel wall.

AIM OF THE STUDY

to detect increased metabolic activity in abdominal aortic aneurysms (AAA) by means of positron emission tomography (PET-imaging).

STUDY DESIGN

twenty-six patients with AAA underwent PET-imaging.

RESULTS

in ten patients, PET-imaging revealed increased fluoro-deoxy-glucose (18-FDG) uptake at the level of the aneurysm. Patients with positive PET-imaging had one or more of the following elements in their clinical history: history of recent non-aortic surgery (n = 4), a painful inflammatory aortic aneurysm (n = 2), moderate low back pain (n = 2), rapid (> 2;5 mm in 6 months) expansion (n = 4), discovery by PET-scan of a previously undiagnosed lung cancer (n = 3) or parotid tumour (n = 1). Five patients with a positive PET scan required urgent surgery within two to 30 days. Among the 16 patients with negative PET-imaging of their aneurysm, only one had recent non-aortic surgery, none of them required urgent surgery, only two had a rapidly expanding AAA, and in only one patient, PET-imaging revealed an unknown lung cancer.

CONCLUSION

these data suggest a possible association between increased 18-FDG uptake and AAA expansion and rupture.

Cloning and characterization of ADAMTS-14, a novel ADAMTS displaying high homology with ADAMTS-2 and ADAMTS-3

The processing of amino- and carboxyl-propeptides of fibrillar collagens is required to generate collagen monomers that correctly assemble into fibrils. Mutations in the ADAMTS2 gene, the aminopropeptidase of procollagen I and II, result in the accumulation of non-fully processed type I procollagen, causing human Ehlers-Danlos syndrome type VIIC and animal dermatosparaxis. In this study, we show that the aminopropeptide of type I procollagen can be cleaved in vivo in absence of ADAMTS-2 activity and that this processing is performed at the cleavage site for ADAMTS-2. In an attempt to identify the enzyme responsible for this alternative aminoprocollagen peptidase activity, we have cloned the cDNA and determined the primary structure of human and mouse ADAMTS-14, a novel ADAMTS displaying striking homologies with ADAMTS-2 and -3. The structure of the human gene, which maps to 10q21.3, and the mechanisms of generation of the various transcripts are described. The existence of two sites of initiation of transcription, in two different promoter contexts, suggests that transcripts resulting from these two sites can be differently regulated. The tissue distribution of ADAMTS-14, the regulation of the gene expression by various cytokines and the activity of the recombinant enzyme are evaluated. The potential function of ADAMTS-14 as a physiological aminoprocollagen peptidase in vivo is discussed.

In vitro tubulogenesis of endothelial cells by relaxation of the coupling extracellular matrix-cytoskeleton

OBJECTIVE

This investigation aimed at determining the importance of the rigidity of the adhesive support and the participation of the cytoskeleton in tubulogenesis of endothelial cells in vitro.

METHODS

The morphotype, biosynthetic phenotype and cytoskeleton organization of human umbilical vein endothelial cells (HUVEC) were analyzed on supports of variable mechanical resistance.

RESULTS

Western blot analysis revealed a strong reduction of the expression of actin and focal-adhesion plaque (FAP) proteins in HUVEC organized in tube-like structures (TLS) on soft matrigel or on matrigel co-polymerized with heat-denatured collagen as compared to HUVEC remaining in a monolayer pattern on rigid matrigel-coat or on matrigel co-polymerized with type I collagen. Human skin fibroblasts morphotype was not altered in these culture conditions and the pattern of FAP proteins and actin was not modulated. By using polyacrylamide gels polymerized with various concentrations of bis-acrylamide to modulate the mechanical resistance of the support and cross-linked to a constant amount of gelatin to provide an equal density of attachment sites, it was shown that the less rigid the support, the more endothelial cells switched to a tube-like pattern. Collagen type I-induced tubulogenesis was accompanied by a profound and reversible remodeling of the actin-FAP complex suggesting a weakening of the bridging between extracellular matrix (ECM) and the cytoskeleton. Human skin fibroblasts and smooth muscle cells, used as control cells, adhered strongly to the collagen, did not form TLS and their network of actin stress fibers was not remodeled. The inhibition of collagen type I-induced tubulogenesis by agents altering the actin cytoskeleton-FAP complex including calpain type I inhibitor, orthovanadate, KT5720 and jasplakinolide, further supports the determinant role of mechanical coupling between the cells and the matrix in tubulogenesis.

CONCLUSIONS

A reduced tension between the endothelial cells and the extracellular matrix, originating in the support or within the cells is sufficient to trigger an intracellular signaling cascade leading to tubulogenesis, an event mimicking one of the last steps of angiogenesis.

An interleukin-1 loop is induced in human skin fibroblasts upon stress relaxation in a three-dimensional collagen gel but is not involved in the up-regulation of matrix metalloproteinase 1

The integrin-mediated stress relaxation as it occurs in a retracting three-dimensional collagen gel (RCG) is accompanied by a large up-regulation of the interstitial collagenase, matrix metalloproteinase 1 ((MMP-1), EC 3.4.24.7), regulated notably by interleukin-1 (IL-1), phorbol esters, and cytoskeleton-disrupting drugs as cytochalasin D (CD). The repression of MMP-1 up-regulation in RCG by cycloheximide suggested the participation in the regulation process of a de novo synthesized intermediary component. We demonstrate here that culture of human skin fibroblasts in RCG or in CD- and 12-O-tetradecanoylphorbol-13-acetate (TPA)-treated monolayers resulted in the activation of an IL-1 autocrine feedback loop that was switched off by the naturally occurring IL-1 receptor antagonist (IL-1RA), a blocker of the common IL-1 receptor. The IL-1RA did not suppress the MMP-1 up-regulation induced in RCG nor in CD-treated cells, indicating that the up-regulation of MMP-1 and the IL-1 autocrine loop occurred in an independent way, while the TPA-induced MMP-1 expression was suppressed by the receptor antagonist. The RCG- as well as the TPA-, IL-1-, and CD-induced up-regulation of both MMP-1 and IL-1 was totally suppressed by protein tyrosine kinases inhibitors. In contrast bisindoylmaleimide, at a concentration (5 microM) that inhibits the TPA-induced protein kinase C activity, suppressed the CD-induced MMP-1 expression but did not or barely altered that induced in RCG or by IL-1. None of the other tested inhibitors of a variety of signaling pathways including those used by integrins was able to suppress the RCG or CD-induced MMP-1. These results point to a potent regulation of MMP-1 by mechanical stress relaxation, a process depending on de novo protein synthesis and occurring independently of the activation of an IL-1 autocrine feedback loop.

Modulation of expression and assembly of vinculin during in vitro fibrillar collagen-induced angiogenesis and its reversal

A model of collagen-induced in vitro angiogenesis was used to investigate the modulation of expression and assembly of focal adhesion plaque-associated proteins during the process of differentiation. Human umbilical vein endothelial cells (HUVEC), first attached on an adhesive substratum (gelatin-, fibronectin-, or laminin-coated dish) or adherent collagen gel and then covered by an overlaying collagen get, organized within 3-4 days in tube-like structures (TLS). Removing the overlaying collagen gel from fully differentiated HUVEC induced a reversion of the process and HUVEC returned to a monolayer pattern. Modulations of focal adhesion-associated proteins occurring in HUVEC during the in vitro differentiation process and its reversal were investigated by Western blot analysis. A significant decrease of expression of vinculin, the integrin alpha2 subunit, talin, alpha-actinin, and actin was observed in TLS whereas the amount of FVIII-related antigen did not vary as compared to control monolayer cultures. During reversal, all the reduced proteins were markedly reexpressed. Human skin fibroblasts (HSF), submitted to the same experimental conditions, did not form TLS. Most of the focal adhesion proteins in HSF were similarly modulated by an overlaying collagen gel with the exception of vinculin, which was not modified. This particular protein was therefore more thoroughly investigated. In a nondifferentiated monolayer of HUVEC, a significant proportion of vinculin was organized into a detergent-resistant juxtamembranous structure (focal adhesion plaque) which disassembled early in TLS formation and reassembled during the reversal of the process. The reduction of vinculin during TLS formation was preceded by a downregulation of its mRNA while this mRNA was upregulated during reversal of the morphotype. These results suggest that the modulations of the cytoskeletal and focal adhesion proteins and more specifically of vinculin coupled to its subcellular redistribution are critical and early events in the cascade of mechanochemical signaling during in vitro angiogenesis induced by fibrillar collagen.

Biochemical analysis of heterotopic ossification in spinal cord injury patients

Heterotopic ossification (HO) represents a frequent complication in spinal cord injury (SCI) patients. Samples of HO taken from SCI patients were studied and compared to normal bone. We used a procedure of bone particle fractionation (according to their degree of mineralisation) which allowed us to establish a profile reflecting the metabolic remodeling of bone and to analyse the organic matrix of the newly synthesised tissue. In paraplegic patients, we noted that there was a large increase of the proportion of a degree of calcified bone in the HO as we had previously observed in cortical as well as in cancellous bone of the same patients. Based on aminoacid analyses, we observed in the newly synthesised organic matrix of HO a decreased proportion of hydroxyprolyl residues resulting either from an alteration of the prolyl hydroxylation or from the presence of an excess of non-collagen polypeptides. These results are similar to those seen in sublesional bone of the SCI patients. This study demonstrates that HO is a newly formed bone which has a high rate of turnover as is seen in growing bone. This must be taken into account for the treatment of the patients.

Enhancement of tumorigenicity of human breast adenocarcinoma cells in nude mice by matrigel and fibroblasts

The failure of MCF7 cells to induce the formation of tumours after sub-cutaneous inoculation into athymic nude mice can be obviated by the simultaneous injection of an extract of basement membrane proteins (matrigel). Tumour growth is promoted and the latency period is low (2 to 4 weeks). In the absence of matrigel, the simultaneous inoculation of fibroblasts and MCF7 cells also resulted in the development of tumours, but with a longer latency period (about 2 months). The tumorigenic synergy between matrigel and fibroblasts was evidenced by co-inoculating MCF7 cells MDA-MB 231 cells with fibroblasts and matrigel. This co-inoculation decreased the delay of appearance of the tumours and/or accelerated the tumour growth, depending upon the number of fibroblasts injected. Repeated injections of fibroblasts conditioned medium, at the site of inoculum of tumour cells also enhanced tumour growth, suggesting the involvement of soluble factors secreted by fibroblasts. Histologically, tumours induced by co-inoculation of tumour cells and fibroblasts contained more stromal structures including vimentin-positive cells, fibronectin and interstitial collagens. These data suggest that human tumours may be reconstituted and grown in athymic nude mice using basement membrane components and fibroblasts as inductors.

Kinetic aspects of gingival and periodontal ligament fibroblast attachment to surface-conditioned dentin

An in vitro model has been developed for measurement of initial attachment of 3H-labeled human gingival fibroblasts (HGF) and periodontal ligament cells (HPDL cells) to sieved dentin powder. Reproducible attachment was obtained and was closely related to the number of plated cells, the amount of dentin powder, the temperature, and the time (from 0 to 6 h) of incubation. HGF and HPDL cells had a high affinity for untreated dentin. Heat-denatured BSA coating of the dentin fully inhibited cell attachment, while a fibronectin coating had no significant effect. A surface conditioning of the dentin grains by 3% citric acid or by 2.5% minocycline-HCl increased the initial attachment of HPDL cells significantly (p < 0.05). Minocycline-HCl was more efficient than citric acid in that respect. In addition, HGF attachment to untreated dentin was highly significantly improved (p < 0.005) by a pre-incubation of the cells with 50 micrograms/mL of minocycline, and there was also indication (p = 0.067) of improvement by the presence of minocycline in the attachment medium, with a maximum of efficacy at 110 micrograms/mL. These results suggest that minocycline-HCl directly influenced the attachment properties of fibroblastic cells and that citric acid and minocycline-HCl could act by different mechanisms. HGF and HPDL cells originating from the same patient displayed no significant difference in their attachment to dentin in this model.

The stimulation of fibroblasts' collagen synthesis by neoplastic cells is modulated by the extracellular matrix

Human fibroblasts cocultured with neoplastic MCF7 cells produce increased amounts of collagen. A maximal stimulation requires direct cell-cell contacts between tumor cells and fibroblasts. However, this effect could be reproduced, although to a lesser extent, by medium conditioned by MCF7 cells, suggesting that it is mediated by a factor produced by MCF7 cells and secreted, at least partly, under a soluble form (Noël et al., 1992). This Collagen Stimulating Factor ("COSF") present in the culture medium displayed a molecular mass between 3,500 to 10,000 daltons, bound to heparin and appeared to be different from the growth factors described until now. The "COSF" can be released from the surface of MCF7 cells by treatment with heparin. The aim of the present work was to investigate the influence of various extracellular matrix components on the production and the release of "COSF". A 3- to 4-fold enhancement of collagen synthesis was observed in coculture on plastic and collagen type I substrates without significant modification of the non-collagen proteins. The increased collagen synthesis was paralleled by an elevation of specific collagen mRNAs level suggesting a regulation at a pretranslational level. On the opposite, in the presence of soluble or insoluble laminin, this stimulation was abolished. Similarly, coculture on "reconstituted basement membrane matrix", matrigel, did not increase collagen production. The "COSF" was found to bind to matrigel and could be released from the basement membrane matrix by treatment with heparin.

Modulation of collagen and fibronectin synthesis in fibroblasts by normal and malignant cells

The influence of various normal and malignant human cells on the level of collagen synthesis by human fibroblasts was tested in coculture. As revealed by immunoperoxidase staining, in cocultures with breast adenocarcinoma cells (MCF7, SA52, T47D) fibroblasts synthesized collagen while tumor cells did not. Fibroblasts displayed increased collagen production without change in the overall protein synthesis. Several other types of cells derived from normal human tissues (keratinocytes, normal mammary cells) or from fibrosarcoma, melanoma, cervical carcinoma, choriocarcinoma, or other breast adenocarcinoma (SW613, MDA, BT20) did not affect collagen synthesis of fibroblasts. Although to a lesser extent, this stimulating effect was reproduced by using the conditioned medium (CM) of the active cells but not with CM of the other cell types. A slight stimulation was also obtained when tumoral MCF7 cells and fibroblasts shared the same medium but were physically separated, suggesting that close contact was required for optimal stimulation of collagen synthesis. The collagen synthesis stimulating activity was not related to a modification of fibroblast proliferation rate. The production of collagen types I, III, and VI and fibronectin were increased in cocultures of fibroblasts with MCF7 cells. The increased synthesis of collagen types I and III and fibronectin was paralleled by similar changes in the steady-state level of their mRNAs. On the contrary, the increased production of collagen type VI appeared regulated at a post-transcriptional level.

Altered response of progeria fibroblasts to epidermal growth factor

The Hutchinson-Gilford syndrome (progeria) is a rare disorder in childhood characterized by premature and accelerated aging. This study reports the effect of a potent growth factor, EGF, on the proliferative capacities and extracellular matrix macromolecules and collagenase expression of two strains of progeria skin-derived cells. At low population doubling levels (PDL less than 10), confluent cultures of progeria fibroblasts made quiescent by lowering the concentration of serum in the medium did not respond to EGF while the mitotic activity of normal PDL-matched fibroblasts was almost maximally restored upon addition of EGF. No obvious difference between normal and low PDL progeria fibroblasts was observed in the number and in the affinity of the receptors measured by [125I]EGF binding. The synthesis of collagen and non-collagen proteins was similar in normal and affected cells at low and high serum concentration and both types of cells responded to EGF by a specific inhibition of collagen synthesis. Besides a normal level of mRNA coding for type I and type III collagens, collagenase and laminin, progeria fibroblasts expressed a high level of elastin and type IV collagen mRNA. Like normal fibroblasts, progeria cells responded to EGF by a decrease in the level of mRNA for fibrillar collagens and elastin. In contrast, a complete lack of response to EGF was observed for collagenase mRNA whereas the expression of this enzyme was strikingly induced by EGF in normal PDL-matched cells. The abnormal expression of type IV collagen was not significantly modified by EGF. At PDL greater than 10, progeria cells exhibited features of senescence. A significant reduction of collagen synthesis was observed and no further inhibition by EGF was recorded.

Two unrelated children with partial trisomy 1q and monosomy 6p, presenting with the phenotype of the Larsen syndrome

Two unrelated children presented with similar clinical features (facial dysmorphism and multiple joint dislocations) suggesting the diagnosis of Larsen syndrome. Both carried an inherited unbalanced translocation resulting in partial trisomy 1q and partial monosomy 6p. Analysis of skin collagen from one of the probands disclosed a decreased alpha 1/alpha 2 chain ratio of collagen type I, increased thermal stability and increased hydroxylation of proline and lysine. The present findings suggest that, as a result of the chromosome rearrangements, both patients have a mutation on a gene involved in collagen production, located either on chromosome 1q or, more probably, on 6p. It is furthermore suggested that other cases of Larsen syndrome are the result of a similar mutation.

Response to epidermal growth factor of skin fibroblasts from donors of varying age is modulated by the extracellular matrix

The present study was undertaken to investigate the effect of epidermal growth factor (EGF) on the biosynthetic activity of skin fibroblasts from donors of varying age and the modulation of their response to this growth factor by culture in a three-dimensional extracellular matrix. When cultured in monolayer on plastic or at the surface of a collagen gel, EGF specifically inhibited collagen synthesis whatever the age of the donor (from 17 to 84 years, n = 11). This inhibition was paralleled by a significant decrease in the steady-state level of procollagen type I mRNAs. When embedded in a three-dimensional floating collagen lattice, EGF stimulated the non-collagen protein (NCP) synthesis in fibroblasts from younger donors (5 out of 6) while fibroblasts from the older ones were not affected. Collagen production by fibroblasts from younger donors was not inhibited as in monolayer (some being even stimulated) while that of the older donors was inhibited as observed in monolayer. The steady-state level of procollagen type I mRNA was not modified by EGF in the three-dimensional culture. No significant difference was observed in the affinity and the number of EGF receptors of the fibroblasts on plastic or embedded in a collagen lattice between young and aged donors. Our results suggest that the environment of the cells can modulate the reactivity to EGF and reveal differences related to in vivo aging.

Factor XIII in scleroderma: in vitro studies

The administration of Factor XIII (FXIII) produces a beneficial effect on the skin lesions in about 50% of the treated patients with progressive systemic sclerosis (PSS). The effect of FXIII on various skin fibroblast functions (proliferation, attachment, biosynthetic activity and mechanical properties) was investigated in vitro using normal and PSS strains. In cell culture, most of the PSS fibroblast strains synthesized excessive amounts of collagen. Other cell functions such as adhesion to collagen I or III, to fibronectin, retraction of collagen lattices, proliferation in low serum concentration and degradation of newly synthesized collagen were not significantly different. The addition of FXIII (I U/ml) inhibited the synthesis of collagen by normal fibroblasts and reduced it in PSS fibroblasts to a level similar to that of normal fibroblasts. This effect was observed for cells cultured on plastic or in a collagen lattice. In the latter, an increased amount of collagen degradation was observed. No significant effect of FXIII on the other cell functions was noted. Excessive collagen production by PSS fibroblasts can be repressed by FXIII in vitro by at least two distinct mechanisms: a reduction of collagen synthesis and an increased degradation of the newly synthesized collagen.

Treatment of alcoholic hepatitis with colchicine. Results of a randomized double blind trial

A randomized double-blind trial of colchicine vs placebo was conducted in 67 patients with histologically proven alcoholic hepatitis, 33 of whom had cirrhosis. Patients with hepatic encephalopathy, ascites, protracted prothrombin time, severe thrombocytopenia, hepatocellular carcinoma, evident lack of discipline or refusal to participate in the trial were not included. Thirty-three patients received colchicine (1 mg/day) and 34 received placebo for 6 months. Blood parameters including N-terminal peptide of type III procollagen were assessed in the serum, and a percutaneous liver biopsy was performed at the start of the trial and after 3 and 6 months. Alcoholic hepatitis and fibrosis scores were established for each biopsy specimen. Twenty-eight percent of patients were lost to follow-up at 3 months, and fifty-two percent at 6 months. One patient died of liver failure. Fifty-eight percent of patients were abstaining from alcohol at 3 months and fifty percent at 6 months. No significant effect of treatment was noted. Nevertheless, improvement in alcoholic hepatitis core at 3 months was more important in the colchicine group than in the placebo group. No side-effects were noted except transient diarrhea. Our results suggest that colchicine has no important effect on the course of alcoholic hepatitis. A trial including of at least 260 patients might be necessary for the observed alcoholic hepatitis score difference at 3 months, favoring colchicine, to be statistically significant.

Laminin and type III procollagen peptide in human preovulatory follicular fluid

The levels of laminin P1 fragment, a marker of basement membrane, and of the aminoterminal sequence of type III procollagen, a marker of interstitial connective tissue, were measured in human preovulatory follicular fluids. The concentrations of these peptides correlated with progesterone levels but not with those of estradiol or testosterone. Immunocytochemical studies confirmed the remodeling of the perifollicular basement membrane and interstitial matrix during oocyte maturation. The studies suggest that monitoring of the ovarian connective tissue macromolecules could be useful for estimating follicular maturation.

Antagonistic effects of laminin and fibronectin in cell-to-cell and cell-to-matrix interactions in MCF-7 cultures

During morphogenesis, tumor progression and metastasis, cell adhesion, dissociation, and migration result from a complex balance between cell-to-cell and cell-to-matrix interactions. Two different organization patterns of MCF-7 cells were induced by different extracellular matrix proteins. When plated on plastic or polymeric type I collagen gel used as a model of interstitial matrix, MCF-7 cells spread and grew in monolayer. When cultured on a solid gel of basement membrane (BM) proteins (85% laminin) used as a model of BM, cells formed clusters attached to the matrix. Matrix proteins regulated these two types of cell organization by preferentially promoting cell-to-cell or cell-support interactions. On plastic in the presence of soluble laminin or on laminin-coated dishes, cells also formed clusters. Addition of soluble fibronectin induced spreading of the cells, suggesting that laminin and fibronectin have competitive antagonistic effects on MCF-7 cell morphology. Antilaminin antibodies inhibited cluster formation and attachment, emphasizing the important role of this glycoprotein not only in promoting cluster attachment but also in cell-to-cell contact formation. Such effects of extracellular matrix proteins could play significant roles in tumor progression and metastasis.

Fibroblasts induce the assembly of the macromolecules of the basement membrane

The mechanism regulating the deposition of basement membrane components (BMCs) in a polymeric structure at the junction with the connective tissues is not yet understood. Cultures and cocultures of epithelial BMC-producing cells (L2 or PER cells) and fibroblasts were prepared in several experimental conditions and the organization of BMCs was studied by immunofluorescence. The pattern of BMCs in pure cultures of L2 or pulmonary epithelial rat (PER) cells consisted of intra- and extracellular granular deposits. At very high density, the cell contours were also underlined by a disrupted network of BMC deposits. A different fibrillar plexus--containing laminin, collagen type IV, and heparan-sulfate proteoglycan resistant to deoxycholate treatment and distant from the cell membrane--was observed in cocultures of L2 or PER cells with fibroblasts. Fibrils of fibronectin and/or collagen type I were most often dissociated from this plexus of BMCs. Similar results were obtained by adding a conditioned medium of L2 or PER cells to confluent fibroblasts, even when the cells were killed. Pure laminin also bound to the fibroblast layer. A coated film of fibronectin or polymeric collagen type I was unable to bind BMC provided by a conditioned medium. It is suggested that molecule(s) synthesized by fibroblasts and deposited in the pericellular matrix are involved in the assembly of BMCs.

Contraction of collagen lattices by fibroblasts from patients and animals with heritable disorders of connective tissue

Fibroblasts derived from patients and animals presenting various heritable connective tissue disorders were investigated for the ability to retract a reconstituted collagen matrix. When seeded into gels, dermatosparactic calf and sheep fibroblasts did not exhibit the elongated shape of normal fibroblasts and did not contract the collagen lattice to the same extent as control fibroblasts. In contrast, several cell strains obtained from patients with Ehlers-Danlos syndrome type VII displayed contractile properties for collagen gels similar to controls. Delayed contraction was noted by two strains of fibroblasts from patients with Ehlers-Danlos syndrome type IV, whereas fibroblasts from patients with osteogenesis imperfecta, Marfan syndrome and cutis laxa had normal retraction properties.

Bone remodeling during the development of osteoporosis in paraplegia

Osteoporosis developing during the first weeks after the onset of traumatic paraplegia was studied with cortical and cancellous samples of iliac crest and tibia of 14 patients, and compared to normals. We used a procedure of bone particle fractionation (according to degree of mineralization) that allowed us to establish a profile reflecting the metabolic remodeling of bone and to analyze the organic matrix of the newly synthesized tissue. In paraplegics, we observed a large increase in the proportion of little calcified bone in the cortical as well as in the cancellous bone. Based on amino acid analyses, we found a decreased number of hydroxyproline residues in the newly synthesized organic matrix from paraplegia bone resulting either from an alteration of the prolyl hydroxylation or from the presence of an excess of noncollagen polypeptides. These results, together with previously published data reporting increased urinary hydroxyproline and calcium kinetic parameters, suggest an enhanced rate of skeletal remodeling in acute paraplegia. When investigated 2 years after injury, the patterns of distribution approach that of normal subjects.

Antibodies to laminin in preeclampsia

Laminin is a large basement membrane glycoprotein localized in the trophoblast, glomerular basement membrane and in the mesangial matrix of human glomeruli. It promotes the attachment of epithelial cells to basement membrane collagen. We have found that 14 sera from 52 patients with severe preeclampsia or eclampsia contain IgG and IgM antibodies which react with placental and kidney basement membranes. These antibodies were specific for laminin and did not react with other basement membrane proteins. They were able to fix complement. They have been demonstrated by radial immunodiffusion, radioimmunoassay and immunofluorescence blocking studies. In primary cultures they were shown to impair the attachment of trophoblast cells to basement membrane collagen. High levels of circulating immune complexes were detected only in sera from preeclamptic patients with circulating antibodies to laminin. The auto-antibodies to laminin could play a major role in the pathogenesis of severe preeclampsia by impairing the attachment of trophoblast cells to placental basement membranes and by fixation to the glomerular basement membranes and mesangial matrix.

Nevi of connective tissue. A reappraisal of their classification

Nevi of connective tissue may be conveniently divided according to clinical and pathologic presentations into two types, namely, the adventitial and the reticular. Nevi of adventitial connective tissue are usually small and situated on the extremities. They are characterized by accumulations of fibroblasts and apposition of collagen around adnexa and vessels. Nevi of reticular connective tissue are usually situated on the trunk. They consist of faulty distributions and amounts of collagen bundles, elastic fibers, or proteoglycans.

Pathogenesis of ulcerations in deficiency of prolidase. The role of angiopathy and of deposits of amyloid

The structure of the skin and the pattern of alteration in chronic ulcerations associated with deficiency of prolidase have been studied superficially in the past. We examined histologically several biopsies taken from apparently normal skin and from ulcerations afflicting a young woman with such a syndrome. Deposits of amyloid were found within the walls of medium-sized vessels and occasionally occluding their lumens. Impaired cutaneous microcirculation resulting from statis, moderate vasculitis, and abnormal structure of the dermis may be responsible for the regional preponderance of deposits of amyloid and ulcerations in the legs.

Radioimmunoassay for the amino-terminal sequences of type III procollagen in human body fluids measuring fragmented precursor sequences

Antisera specifically directed against the amino-terminal precursor sequence of bovine p-N-collagen type III (Col 1-3 III) have been raised in rabbit. When tested in a radioimmunoassay, parallel displacement curves and complete cross-reactivity were observed between bovine and human purified Col 1-3 III. However, these displacement curves were not parallel to that obtained with serially diluted human sera which presented a smoother slope. Cleavage of the Col 1-3 III peptide by collagenase at high temperature yielded an immunoreactive preparation containing two smaller peptides (Col 1 plus Col 2) III. The displacement curves obtained with human or bovine (Col 1 plus Col 2) preparations were parallel to those obtained with serially diluted human sera or other human body fluids (amniotic and ascitic fluids). Quantitative measurements of the circulating antigen in normal and pathological conditions are possible only when the (Col 1 plus Col 2) is used as standard antigen. This radioimmunoassay represents an original and simple technique offering good accuracy. The amount of (Col 1 plus Col 2) III in human adults is 69.1 +/- 27.7 ng/ml, with a distribution of frequency close to the normal. It is increased in liver cirrhosis and other conditions characterized by an active neoformation of connective tissue.

Immunohistologic and ultrastructural study of the sclerotic skin in chronic graft-versus-host disease in man

Thirteen skin biopsies were performed on 8 patients at different stages of skin sclerosis in chronic graft-versus-host disease (GVHD). On the same skin biopsies an immunostaining with antibodies directed against Types I and III procollagen, Types I, III, IV, V collagen, and laminin, and an ultrastructural study were performed. Alterations were observed at the dermal-epidermal junction and in the superficial dermis with a large deposit on Type III procollagen in the incipient scleroses and of Type I procollagen in the oldest ones. In this sclerotic superficial dermis, collagen fibers of irregular diameter were associated with mast cells and active fibroblasts, macrophages, and lymphocytes in close contact. The skin sclerosis in chronic GVHD might be considered a form of cutaneous fibrosis with features of excessive tissue repair related to an immunologic reaction between lymphocytes of the graft and tissue host cells.

Accumulation of several basement membrane proteins in glomeruli of patients with preeclampsia and other hypertensive syndromes of pregnancy. Possible role of renal prostaglandins and fibronectin

The glomerular lesions of preeclampsia consist of swelling of endothelial cells, interposition of mesangial cells and matrix between the endothelial cells and the glomerular basement membrane, and organization of subendothelial deposits of incompletely characterized material. Fibrin and immunoglobulins have previously been localized to these deposits. Laminin, a large basement membrane glycoprotein, type IV collagen, fibronectin, and a basement membrane proteoglycan were found in moderate amounts in the mesangium and prominently in the thickened glomerular capillary walls of patients with preeclampsia or other hypertensive syndromes of pregnancy. Fibrin showed the same pattern of distribution as that of fibronectin. The material deposited in the subendothelial layer of the capillary loops thus consists not only of plasma-derived proteins but also structural components of the glomerular basement membrane and of the mesangial matrix. Type I collagen deposits were demonstrated only in mesangium of pregnant patients with chronic or recurrent hypertension. Glomerular epithelial and mesangial cells synthesize in vitro the basement membrane proteins that accumulate in glomeruli of pregnant hypertensive patients. We have tested the influence of some of the pathophysiologic changes occurring during preeclampsia on the biosynthesis of collagen by rat glomerular epithelial and mesangial cells. Addition of indomethacin to the cultures transiently inhibited the synthesis of prostaglandins (PGE2) and of collagen. Addition of exogenous fibronectin to the media stimulated the production of collagen by mesangial and epithelial cells. Alterations in the metabolism of prostaglandins and the increased deposition of fibronectin observed during preeclampsia could thus play a pathogenic role in the accumulation of basement membrane proteins in glomeruli of these patients.

Characterization of oligosaccharide units of p-N-collagen type III from dermatosparactic bovine skin

p-N-collagen type III was extracted from dermatosparactic and normal fetal bovine skin and purified by ion-exchange chromatography using DEAE- and CM-cellulose. Asparagine-linked sugar chains were fractionated by high voltage paper chromatography from the products obtained after hydrazinolysis and reduction with NaB3H4. These oligosaccharides composed of neutral and acidic components are mannose-containing oligosugars of the complex type. Their abundance is much higher in dermatosparactic p-N-collagen type III.

Immunohistochemical localization of laminin, type IV and type V collagen in basal cell carcinoma

Laminin, type IV and type V collagen were localized in twenty-five basal cell carcinomas (BCCs) by immunofluorescence. All basal cell carcinomas were separated from the connective tissue by a continuous basement membrane (BM) which always contained the three antigenic determinants. Nodular and cystic BCCs, but not pagetoid BCCs, contain linear and globular deposits of these BM components. The linear deposits probably represent BM debris that remains undigested and the globular deposits correspond to residual cytoplasmic fragments occurring during apoptosis. These results suggest that BM components are synthesized by epithelial cells and are secreted to polymerize at the dermo-epidermal junction.

Angioplastic necrolytic migratory erythema. Unique association of necrolytic migratory erythema, extensive angioplasia, and high molecular weight glucagon-like polypeptide

A diabetic patient developed necrolytic migratory erythema with extensive angioplasia and high molecular weight glucagon-like polypeptide. There was no associated neoplasm such as glucagonoma. Lesions in the skin were studied by standard optical microscopy and by radioautography after incorporation of tritiated thymidine. Alterations in the skin begin as focal necrosis in the epidermis and in epithelial structures of adnexa, followed by marked angioplasia and a superficial and deep perivascular dermatitis.

A comparative study between interdermal tests with phytohemagglutinin and delayed hypersensitivity reactions elicited by tuberculin

Intradermal (i.d.) tests with phytohemagglutinin (PHA) and tuberculin are used in clinical practice to evaluate the cell-mediated immunity. The biologic significance of the skin response to PHA, clinically evaluated by the extent of erythema and induration, was studied histologically after incorporation of tritiated thymidine. It was compared to tuberculin tests. The rate of recruitment and the respective amount of inflammatory cells varied between patients and in time. In PHA tests the inflammatory reaction occurred in two phases, the first one consisting in the predominance of polymorphonuclears, the second one being characterized by chemotactism of lymphoblasts many of which synthesized DNA. The "in vivo" reaction to PHA is therefore complex; the same clinical evaluation corresponds to markedly different stages and events in the biological reaction. The histological grading of the PHA test is therefore desirable in the evaluation of the cell-mediated immunity because only the blastic proliferation is of importance in its rating and not the edema and the accumulation of polymorphonuclears.

Proliferation of the characteristic histiocyte of histiocytosis X in the skin

The proliferation of the characteristic histiocyte of histiocytosis X in the skin of a patient with localized lesions of Hand-Schüller-Christian disease has been studied by counting cells in mitosis and cells that incorporated tritiated thymidine. The mitotic index was very low although about one-quarter of the cells were synthesizing DNA. In the deep dermis, many eosinophils were associated with a decreased tendency of the characteristic cells to synthesize DNA. We conclude that in this patient with a localized type of histiocytosis X, the characteristic cells are stimulated to enter the S phase when they are situated close to the epidermis, but there is no evidence that they divide in the skin subsequently.

Significant progress in dermatologic research since 1977

Some active fields of experiment dermatology have been selected to demonstrate the interaction between basic research and clinical dermatology. The identification of the Langerhans cell, the typing of mononuclear cells, and the identification of T cell growth factors have significant implication in contact dermatitis, lymphomas, etc. The group of papovaviruses is better defined in relationship to the type of disease that they produce and its oncogenic potential. Various types of vasculitis are better understood, thanks to research in humoral immunity and complement activation. Melanogenesis and its control by peptides is progressing. New specific proteins have been identified in the connective tissues, and their role has been clarified. Identification of specific proteins of keratinocytes and study of differentiation of these cells have provided useful information and some skin disorders. The control of epidermal cell proliferation and differentiation, through membrane receptors, growth factors, and intracellular enzymes, is progressively giving clues to the understanding of genetic disorders, cancers, the effect of retinoids and phototherapy.

Follicular lymphomatoid papulosis

In two patients who episodically developed eruptions of papules and nodules for many years, the lesions developed at the sites of hair follicles or around ruptured follicular cysts. They were pseudomalignant lymphomas in histologic appearance and benign in biologic behavior. From its limitation largely to follicular adnexa, the condition appears to be a distinct type of lymphomatoid papulosis.

Cell proliferation in a malignant angioendothelioma during sequential chemotherapy

The rate of cellular proliferation was studied in the neoplastic cells of a malignant angioendothelioma and in its inflammatory infiltrate by means of optical radioautography after incorporation ex vivo of tritiated thymidine. One third of the normal looking, as well as the atypical, endothelial cells were engaged in the cell cycle of proliferation. This large pool has been effectively suppressed during subsequent chemotherapy which resulted in partial regression of the neoplasm. The proliferative activity of the infiltrate was higher inside the neoplasm than at its periphery.

Phenytoin dependent fibrosis in polyfibromatosis syndrome

We have followed up the evolution of a polyfibromatosis syndrome in a 20-year-old male treated with diphenylhydantoin for epileptic convulsions. The main symptoms were attributable to fibrosis of the adventitial dermis associated with camptodactyly, knuckle pads, tendinous calcification, osseous hypoplasia of the face, scoliosis with thoracic deformation, and osteolytic changes of wrists, hands and feet. Quantitative variations of the mechanical properties of skin measured in vivo suggested a reversible fibrosing action of diphenylhydantoïn in a genetically predisposed patient.

The relationship between blood pressure and aortic collagen metabolism in renal hypertensive rats

1. Biosynthesis and deposition of collagen, as well as DNA and total proteins, are increased in aortae of rats after 1, 3 and 6 weeks of hypertension. 2. The maximal increase in the rate of synthesis of collagen is observed within one week of hypertension when the stress to the arterial wall is maximal. 3. Reserpine administration prevents hypertension and inhibits the increase of collagen metabolism. 4. At any time of evolution of the hypertension, a linear positive correlation is found between the collagen content in the aorta and the level of blood pressure. 5. These data suggest that synthesis of matrix components by the arterial smooth-muscle cells is controlled by variation in the blood pressure level and is not a direct consequence of circulating humoral factors liberated by the ischaemic kidney.

Interaction between collagen type I and type III in conditioning bundles organization

Type I and type III collagen extracted from skin was purified by differential salt precipitation and chromatography. By heating to 37 degrees, type I formed after a lag phase a floppy and opalescent gel of high optical density and type III formed more rapidly a translucent and rigid gel of low optical density. Addition of type III to type I resulted in formation of gels of reduced optical density and lag phase related to the proportion of type III added. Phase contrast and scanning electronmicroscopy demonstrated the formation of thick bundles of type I, thin fibers of type III and bundles of intermediate size related to the proportion of type III. The relationship between collagen type and bundle architecture might prove most significant in conditioning the mechanical properties of the connective tissues in normal and pathological conditions.

Type III procollagen and collagen in skin

A form of collagen, containing three alpha chains of type III, can be extracted from foetal calf, calf and rat skin under physiological conditions. This native collagen was purified by DEAE-cellulose chromatography and then was analysed by polyacrylamide gel electrophoresis which showed it consisted of several high molecular weight components, the size of gamma components and larger species. Prior reduction in dithiothreitol dissociated these large polymers into two components: the minor one migrated between the alpha1 (I) and alpha2 chains while the predominant one migrated between the alpha and beta chains. These two monomers were isolated by CM-cellulose chromatography. The minor one, which eluted between the alpha1 and alpha2 chains, had a molecular weight of approx. 95 000; its amino acid composition was similar to that of alpha1(III). The major one eluted in the alpha1 region and had a molecular weight of approx. 120 000; its amino acid composition, while similar to that of the alpha1(III) chain, differed in detail, and it is presumed to be a pro-alpha1(III) chain. Following pepsin digestion, the native collagen remained as a disulfide-bonded trimer which dissociated into only one component, a1(III), when denatured in dithiothreitol. These results suggest that the original, extracted protein consisted primarily ofa precursor form of type III collagen. This procollagen did not polymerize when heated at 37 degrees C and did not form the usual segment long spacing aggregates under suitable conditions. It was not modified by incubation with a purified procollagen peptidase preparation. This appears to be the first example of the isolation of type III (pro)collagen by extractive methods, without resorting to tissue digestion by proteolytic enzymes.