Tocilizumab potentially prevents bone loss in patients with anticitrullinated protein antibody-positive rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with a high risk of osteoporosis and fracture. Interleukin (IL)-6 inhibitors may suppress osteoclast activation. Anticitrullinated protein antibody (ACPA) titers are inversely associated with bone mineral density (BMD). However, the differential effect of ACPA on bone turnover marker (BTM) and BMD changes after IL-6 inhibition remains unclear. This prospective study recruited patients with active RA with inadequate response to methotrexate or biologics. BMD was measured before and after 2-year tocilizumab (TCZ) treatment. Serum osteocalcin, N-terminal propeptide of type I collagen (P1NP), and C-terminal cross-linking telopeptide of type I collagen (CTX) levels were assessed at the baseline and after treatment. We enrolled 76 patients with RA (89.5% women, age: 57.2 ± 13.3 years) receiving TCZ. The 28-joint disease activity score was negatively correlated with BMD and T-scores of the lumbar spine and bilateral femoral neck. ACPA-positive patients had lower lumbar spine and femoral neck T-scores. After 2-year TCZ treatment, CTX levels significantly decreased (0.32 ± 0.21 vs. 0.26 ± 0.17, p = 0.038). Femoral neck BMD increased significantly (0.71 ± 0.22 vs. 0.69 ± 0.55, p = 0.008). Decreased CTX levels and improved BMD were observed only in ACPA-positive patients. After treatment, femoral neck BMD significantly increased only in patients receiving a glucocorticoid dose of ≥5 mg/day. Two-year TCZ treatment reduced bone resorption and increased femoral BMD in ACPA-positive patients. The net effects of glucocorticoids and IL-6 inhibition on BMD imply that strict inflammation control might affect bone metabolism.

Measurement of amino terminal propeptide of type III procollagen (PIIINP) employing the ADVIA Centaur platform. Validation, reference interval and comparison to UniQ RIA

BACKGROUND

Recently, measurement of amino terminal propeptide of type III procollagen (PIIINP) was introduced as a part of the hepatic cirrhotic marker enhanced liver fibrosis™ test on the automated ADVIA Centaur(®) immunoassay platform (Siemens Healthcare Diagnostics Inc., Tarrytown, NY, USA). In this article, we show that the Centaur PIIINP may be used in place of the much more labor-intensive RIA method, and we present an age stratified reference interval.

METHODS

We analyzed four control samples 20 times over a period of 5 days. Centaur PIIINP assay measurements were compared with the widely used UniQ PIIINP RIA assay (Orion Diagnostica, Espoo, Finland) using 55 patient samples (range=3.7-43.3 µg/L). Furthermore, we established a reference interval based on samples from 287 blood donors.

RESULTS

In the concentration range 2.5-11.9 µg/L, the total imprecision was below 8%. Comparison with the UniQ PIIINP RIA assay yielded: Centaur PIIINP µg/L = 1.9 × (UniQ PIIINP RIA) + 0.6 µg/L, r2=0.94. The reference interval for the Centaur PIIINP assay showed no gender difference but was stratified by age [4.0-11.0 µg/L (18-40 years) and 3.5-9.5 µg/L (41-70 years)].

CONCLUSIONS

We conclude that the Centaur PIIINP assay is suitable for routine use with our newly defined reference interval. The results obtained by Centaur correlates well with those obtained by the previously employed RIA, though the absolute values are higher.

[Correlation of lymphocytes and PIIINP with the combined pulmonary fibrosis and emphysema]

AIM

To approach the relationships among inflammation, immune response, and fibrosis in combined pulmonary fibrosis and emphysema (CPFE) through the observation of distributions of lymphocyte subtypes, the variation of Pro-collagen III N-terminal peptide (PIIINP) expression and the severity of pulmonary fibrosis (PF) in CPFE.

METHODS

From March 2005 to March 2007, 21 diagnosed cases of CPFE, 25 diagnosed cases of idiopathic pulmonary fibrosis (IPF) and 19 cases of controls were involved in the study from the First Affiliated Hospital of Xi'an Jiaotong University. The patients were subjected to the following investigations including pathological changes in lung tissue biopsy specimens by light microscopy, counting and classification of inflammatory cells out of bronchoalveolar lavage fluids (BALF), determination of T-lymphocyte subtypes by flow cytometry (FCM), and detection of PIIINP level in BALF and blood serum by radioimmunoassay.

RESULTS

The pathological data showed higher degree of fibrosis in IPF group than that in CPFE group (P<0.01), but the level of fibrosis in the two Zgroups had nothing to do with smoking status (P>0.05). The inflammatory cells and lymphocyte cells in BALF were more in CPFE group than those in IPF and control groups (P<0.05, P<0.01 respectively). The FCM showed CPFE group had more CD8+ T-lymphocytes than IPF and control groups (P<0.05), whereas CPFE and IPF groups showed significantly lower CD4+/CD8+ ratio than the control group (P<0.01). There was no significantly statistical difference in the percentage of CD4+ T-lymphocytes among the three groups (P>0.05). CPFE and IPF groups exhibited significantly higher level of blood PIIINP than the control group (P<0.01), while IPF group showed markedly higher level of blood PIIINP than CPFE group (P<0.01). BALF and blood level of PIIINP were positively correlated (gamma=0.82).

CONCLUSION

The pulmonary fibrosis in CPFE shows intrinsic characteristics, with smoking not being the major or direct PF-driven factor. The CPFE group showed significant inflammation predominated by T-lymphocytes, especially CD8+; T-lymphocyte, as compared with the IPF and control groups, hence pointing to the fact that a novel anti-lymphocytes and immune regulation strategy may be useful for disease intervention. Blood serum PIIINP may be used as a marker for early detection of CPFE and also as a monitor for efficacy of treatments.

FACIT collagen (1alpha-chain) is expressed by hemocytes and epidermis during the inflammatory response of the ascidian Ciona intestinalis

Based on previous cloning and sequencing study, real-time PCR and in situ hybridization assays of the inflamed body wall of LPS-injected Ciona intestinalis showed the enhanced gene expression of a collagen with FACIT structural features (Ci-type IX-Col 1alpha-chain). By using specific antibodies raised against an opportunely chosen Ci-type IX-Col synthetic peptide, the fibroblast property of hemocytes challenged in vitro with LPS (at 4h) was displayed by flow cytometry, while immunocytochemistry identified hemocytes with large granules (morula cells) as collagen-producing cells. Hemocyte lysate supernatant analyzed in immunoblotting contained a 60 kDa band identifiable as 1alpha-chain-Ci-type IX-Col. Observations of body wall sections (immunohistochemistry method) supported the role of hemocytes and showed that epidermis expressed Ci-type IX-Col 1alpha-chain in the time course of the inflammatory reaction (within 24h). Transcript and protein were mainly found in the epidermis that outlined the proximal side of the tunic matrix (at 24h after LPS injection), in cells associated with the epidermis at 4 and 192 h. In conclusion, the C. intestinalis inflammatory response to LPS challenge appeared to be composed of a complex reaction set, and for the first time we showed in ascidians a granulation tissue with FACIT-collagen production that could participate in inflammation and wound healing. Like in vertebrates, C. intestinalis acute inflammatory reactions result in a regulated pattern of tissue repair with collagen expression during remodelling. Ci-type IX-Col could be involved in a network of non-fibril-forming collagens that participates in the organization of extracellular matrix and defense responses.

Antibody isotype responses to paramyosin, a vaccine candidate for schistosomiasis, and their correlations with resistance and fibrosis in patients infected with Schistosoma japonicum in Leyte, The Philippines

We examined whether antibody isotype responses to paramyosin (PM), a vaccine candidate for schistosomiasis, are associated with age-dependent resistance and pathology in liver fibrosis using human sera collected from 139 individuals infected with Schistosoma japonicum in Leyte, The Philippines. We report that IgA and IgG3 responses to PM showed a positive correlation with age and that the epitopes responsible were localized predominantly within the N-terminal half of PM. In addition, the IgG3 response to PM was associated with serum level of procollagen-III-peptide (P-III-P), an indicator of progression of liver fibrosis. These results imply that IgG3 against PM may not only provoke age-dependent resistance to S. japonicum infection but also enhance liver fibrosis. In contrast, levels of IgE to PM and to multiple PM fragments showed a negative correlation with P-III-P level. Thus, in contrast to IgG3, increases in PM-specific IgE may contribute to suppression of liver pathogenesis in schistosomiasis.

Development and clinical application in arthritis of a new immunoassay for serum type IIA procollagen NH2 propeptide

Type II collagen, the most abundant protein of cartilage matrix, is synthesized as a procollagen molecule including the N-(PIINP) and C-(PIICP) propeptides at each end. Type II procollagen is produced in two forms as the result of alternative RNA splicing. One form (IIA) includes and the other form (IIB) excludes a 69-amino acid cysteine-rich globular domain encoded by exon 2 in PIINP. During the process of synthesis, these N-propeptides are removed by specific proteases and released in the circulation, and their levels are believed to reflect type II collagen synthesis. In this chapter we describe the development of a specific enzyme-linked immunosorbent assay (ELISA) for the measurement of the IIA form of PIINP (PIIANP) in serum based on a polyclonal antibody raised against recombinant human exon 2 fusion protein of type II procollagen. We show that this ELISA is highly specific for circulating PIIANP and has adequate technical precision. In patients with knee osteoarthritis and rheumatoid arthritis, serum PIIANP was decreased by 53% (p < 0.0001) and 35% (p < 0.001), respectively, suggesting that type IIA collagen synthesis is altered in these arthritic diseases. The measurement of serum PIIANP may be useful for the clinical investigation of patients with joint diseases.

Development of an assay for the quantification of type I collagen synthesis in the guinea pig

There is a need for a reliable assay for the quantification of collagen type I synthesis in the guinea pig, an important model for many connective tissue diseases. Procollagen type I C-terminal propeptide (PICP) is the established marker of type I collagen synthesis but, to date, no assay has been developed to measure PICP in guinea pig tissue extracts. A monoclonal antibody, known to cross-react with intact guinea pig procollagen type I (anti-PICP), was tested for its ability to bind soluble guinea pig PICP in crude skin extracts using a biosensor. Anti-PICP was immobilised to the surface of a sensor chip and antibody-antigen binding was detected using the phenomenon of surface plasmon resonance (SPR). The binding component in the SPR-immunoassay was identified as PICP by purification and N-terminal sequencing. Guinea pig PICP was purified from skin by gel filtration, ion exchange chromatography and lectin affinity chromatography. Purified PICP was then biotinylated and used with anti-PICP to develop a competition ELISA that was able to selectively and sensitively measure PICP in extracts of guinea pig connective tissue.

Serum levels of type IIA procollagen amino terminal propeptide (PIIANP) are decreased in patients with knee osteoarthritis and rheumatoid arthritis

OBJECTIVE

The aim of this study was to develop a specific immunoassay for PIIANP and measure its serum concentration in healthy controls and in patients with osteoarthritis (OA) and rheumatoid arthritis (RA). In addition, we investigated circulating forms recognized by antiserum IIA in pools of serum from healthy adults, patients with OA and patients with RA.

DESIGN

Using as immunogen and standard the recombinant human Glutathione S-Transferase (GST)-exon 2 fusion protein of type II collagen, we developed a competitive polyclonal antibody-based ELISA. We compare serum PIIANP levels in 43 patients with knee OA (23 women and 20 men; mean age: 62.6+/-9.6 yr), 63 women with RA (mean age: 54+/-16 yr) and 88 healthy controls (67 women, mean age: 53+/-13 yr and 21 men, mean age: 63+/-7 yr). We randomly selected serum in each group for analyze circulating forms.

RESULTS

The immunoassay we developed demonstrated adequate intra and inter-assay precision (CV<10%) and dilution recovery (mean: 96%), allowing accurate measurements of serum PIIANP from 1.13 to 40 ng/ml. No significant cross-reactivity of the ELISA was observed with purified intact human procollagen type I N-propeptide, circulating thrombospondin and von Willebrand factor, proteins which exhibit significant sequence homology with PIIANP. Western blot analysis showed that antiserum IIA recognized two circulating immunoreactive forms of approximately 80 and 100 KDa respectively in serum from healthy adults, patients with OA and RA but also in a pool of synovial fluids from patients with OA. Serum PIIANP levels were markedly decreased in patients with knee OA (12.0+/-3.2 vs 25.8+/-7.5 ng/ml for OA and controls respectively, P<0.0001) and RA (14.1+/-2.5 ng/ml vs 21.7+/-7.6 ng/ml for RA and controls respectively, P<0.0001). In patients with RA, serum PIIANP levels were higher in those taking low-dose prednisone compared to non-users (15.0+/-2.4 vs 13.5+/-2.4 ng/ml, P<0.05).

CONCLUSIONS

We have developed the first specific immunoassay for serum PIIANP which exhibits adequate technical performances. This assay detects specifically two immunoreactive forms both in healthy adults and patients with arthritis and does not cross react with other proteins with sequence homology with PIIANP. Levels of PIIANP were significantly decreased in patients with knee OA and RA suggesting that type IIA collagen synthesis may be altered in these arthritic diseases. The measurement of type IIA collagen synthesis with this new molecular marker may be useful for the clinical investigation of patients with joint diseases.

Immunolocalization of carboxy-terminal type II procollagen peptide in regenerated articular cartilage of osteoarthritic knees after reduction of mechanical stress

OBJECTIVE

The purpose of this study was to investigate the immunolocalization of carboxy-terminal type II procollagen peptide (pCOL-II-C) in the regenerated articular cartilage grown 1-2 years after reduction of mechanical stress by correction of varus deformity with high tibial osteotomy (HTO) for knees with medial compartmental osteoarthritis.

DESIGN

The series included 24 knees of 16 patients with a mean age of 70 (56-79) years. Synovial fluid and tissue specimens of the regenerated articular cartilage were obtained at the time of plate removal with arthrotomy. Tissue specimens were decalcified and stained with toluidine blue, safranin O, anti-type I and type II collagen and anti-pCOL-II-C. Pineda's histological grading of articular cartilage repair and Okada's grade of immunostaining were employed to assess the regenerated articular cartilage.

RESULTS

In knees with regeneration of articular cartilage, there was a positive linear correlation between the grade of immunostaining and the concentration of synovial fluid pCOL-II-C (r=0.652; P< 0.001). Similarly, a positive linear correlation was observed between the grade of immunostaining and the histological grading score (r=0.683; P< 0.001).

CONCLUSIONS

The immunostaining and synovial fluid concentration of pCOL-II-C decreased in accordance with the progression of articular cartilage regeneration observed after reduction of mechanical stress by correction of deformity with HTO.

Amelioration of relapsing polychondritis in a child treated with oral collagen

Relapsing polychondritis (RP) is a disease characterized by inflammation and the destruction of cartilage. The detection of antibodies to native type II collagen (CII) in the sera of some patients with relapsing polychondritis suggests that autoimmunity to this cartilage specific protein plays a role in the pathogenesis of the disease. RP is so rare that controlled therapeutic trials have not been carried out. We describe herein a child with RP who had amelioration of symptoms and a deviation in the cellular immune response to CII after being treated with daily oral CII as a toleragen.

The carboxyl terminus of type VII collagen mediates antiparallel dimer formation and constitutes a new antigenic epitope for epidermolysis Bullosa acquisita autoantibodies

Type VII collagen, the major component of anchoring fibrils, consists of a central collagenous triple-helical domain flanked by two noncollagenous domains, NC1 and NC2. The NC2 domain has been implicated in catalyzing the antiparallel dimer formation of type VII procollagen. In this study, we produced the entire 161 amino acids of the NC2 domain plus 186 amino acids of adjacent collagenous domain (NC2/COL) and purified large quantities of the recombinant NC2/COL protein. Recombinant NC2/COL readily formed disulfide-bonded hexamers, each representing one antiparallel dimer of collagen VII. Removal of the collagenous helical domain from NC2/COL by collagenase digestion abolished the antiparallel dimer formation. Using site-directed mutagenesis, we found that mutation of either cysteine 2802 or cysteine 2804 alone within the NC2 domain blocked antiparallel dimer formation. In contrast, a single cysteine mutation, 2634, within the collagenous helical domain had no effect. A generated methionine to lysine substitution, M2798K, that is associated with recessive dystrophic epidermolysis bullosa, was unable to form antiparallel dimers. Furthermore, autoantibodies from epidermolysis bullosa acquisita patients also reacted with NC2/COL. We conclude that NC2 and its adjacent collagenous segment mediate antiparallel dimer formation of collagen VII. Epidermolysis bullosa acquisita autoantibodies bound to this domain may destabilize anchoring fibrils by interfering with antiparallel dimer assembly leading to epidermal-dermal disadherence.

Increased amount of type III pN-collagen in human abdominal aortic aneurysms: evidence for impaired type III collagen fibrillogenesis

PURPOSE

This study aimed to characterize the distribution of structural domains of type I and III collagens in the wall of abdominal aortic aneurysms (AAAs), by the use of undilated atherosclerotic aortas (aortoiliac occlusive disease [AOD]) and healthy abdominal aortas as controls.

METHODS

Immunohistochemical staining was applied with antibodies for the aminoterminal propeptides of type I (PINP) and type III (PIIINP) procollagens, which represent newly synthesized type I and III pN-collagens. In addition, an antibody against the aminoterminal telopeptide of type III collagen (IIINTP) was used as a means of detecting maturely cross-linked type III collagen fibrils.

RESULTS

The newly synthesized type III procollagen detected by means of PIIINP staining was concentrated in the media in aneurysmal aortas, whereas type I pN-collagen was localized in the intima in both AAAs and AODs. The healthy aortas showed no immunoreactivity for either PIIINP or PINP. The cross-linked type III collagen, detected by means of IIINTP staining, stained transmurally in all study groups, but appeared more abundant in the media in AAAs.

CONCLUSION

Our results strongly suggest that the metabolism of type III collagen is enhanced in AAAs. Intensive type III pN-collagen staining was present mainly in the media layer in AAAs, suggesting a role of type III collagen in aneurysm formation, whereas type I pN-collagen was present in the intima in both AAAs and AODs, suggesting that type I collagen synthesis is a fibroproliferative response related to the atherosclerotic process. The increased type III pN-collagen in AAAs may result in impaired fibril formation and, thus, in decreased tensile strength of aneurysmal tissue.

Alterations in cartilage type-II procollagen and aggrecan contents in synovial fluid in equine osteochondrosis

The etiology and pathophysiology of osteochondrosis remain poorly understood because it is difficult to obtain material from lesions in the early stage of this disease and because there is no satisfactory experimental animal model. We wished to determine whether there are changes in articular cartilage turnover in equine osteochondrosis, which closely resembles the human disease, by assaying cartilage matrix molecules in synovial fluids. We used immunoassays that measure a keratan sulfate epitope and the epitope 846 on the cartilage proteoglycan aggrecan and the C-propeptide of cartilage type-II procollagen, which is released following the synthesis of this molecule, to analyse synovial fluids from equine tarsocrural joints with and without osteochondrosis. In young horses with osteochondrosis, there was a significant increase of C-propeptide of type-II procollagen accompanied by a decrease in the 846 and keratan sulfate epitopes. The results identify differential alterations in aggrecan and type-II collagen turnover in the cartilage matrix in young animals with osteochondrosis that may contribute to the pathological degeneration of articular cartilage in this disease.

Induction of fibrogenic mediators by fine and ultrafine titanium dioxide in rat tracheal explants

Respirable ambient particles [particulate matter <10 micrometer (PM(10))] are associated with both acute and chronic adverse health effects including chronic airflow obstruction. PM(10) can induce expression of inflammatory and fibrogenic mediators, but there is controversy about the types and/or sizes of particles involved and, in particular, whether ultrafine particles are the major toxic agents. To examine whether particle size affects mediator generation, we exposed rat tracheal explants, an inflammatory cell-free model of the airway wall, to various concentrations up to 500 microgram/cm(2) of fine (0.12 micrometer) or ultrafine (0.021 micrometer) titanium dioxide (anatase), maintained the explants in an organ culture in air for 1-7 days, and used RT-PCR to examine the expression of fibrogenic mediators and procollagen. No increase in gene expression was seen at 1 or 3 days, but at 5 days, ultrafine dust induced a small increase in procollagen. At 7 days, fine titanium dioxide produced significantly greater increases for platelet-derived growth factor (PDGF)-B, transforming growth factor-alpha, and transforming growth factor-beta compared with those by ultrafine dust; both dusts produced similar increases for PDGF-A; and ultrafine dust produced increases in procollagen expression, whereas fine dust had no effect. Expression levels were dose related. Both dusts produced a similar decrease in expression of PDGF receptor-alpha and a similar increase in PDGF receptor-beta. These observations suggest that ultrafine particles are intrinsically able to induce procollagen expression even in the absence of inflammatory cells; that chronic exposure to PM(10) may result in chronic airflow obstruction, in part because of ultrafine particle-mediated increases in airway wall fibrosis; and that chemically identical dusts of differing size can produce quite different patterns of gene expression in the airway wall. Differential upregulation of PDGF receptors does not appear to explain dust-induced fibrosis in this model.

[Manifestation of epidermolysis bullosa acquisita (EBA) in the ENT area]

Epidermolysis bullosa acquisita (EBA) is a rare, chronic, acquired bullous autoimmune dermatosis. It is characterized by the formation of IgG autoantibodies against type VII procollagen of anchoring fibrils with subepidermal formation of bullous lesions and consequent scarring. The epidemiology of this disease and its characteristic clinical findings cannot be completely surveyed at present due to the limited number of available publications. In general, bullous lesions form on the entire integument and can also involve mucosa. The development of scar-related adhesions on the mucosa of the upper airways and esophagus can lead to serious complications that are difficult to treat. We report our experience in managing a 44-year-old male patient in whom the diagnosis of EBA was established in 1993 on the basis of multiple persistent bullous lesions involving the eye, nose, skin and oral, pharyngeal and laryngeal mucosa. After failing previous medical and surgical therapies, interdisciplinary management resulted in the control of active lesions with extracorporal phototherapy and cyclosporin A.

In vitro synthesis of type I collagen: quantification of carboxyterminal propeptide of procollagen type I versus tritiated proline incorporation

Radioimmunoassay of the carboxyterminal propeptide of human type I procollagen has been recently introduced to measure in vitro synthesis of type I collagen by osteoblasts and fibroblasts. However, it has not been assessed whether the equivalent results are obtained with this new assay and with tritiated proline incorporation to collagen protein. To this purpose, both methods were used to quantify synthesis of type I collagen in normal human osteoblast cultures to which fetal calf serum and human serum were added in order to stimulate protein synthesis. A positive correlation in the results obtained by both methods was obtained (r = 0.95, P = 0.0001). Given the technical advantages of detection of levels to carboxyterminal propeptide of type I procollagen, we consider that this is the technique of choice for the quantification of in vitro synthesis of type I collagen by normal human osteoblasts.

Epitope-specific monoclonal antibodies against human C-terminal procollagen alpha1(III)-propeptide

We have generated monoclonal antibodies against recombinant C-terminal human procollagen alpha1(III) propeptide (PIIICP), produced in E. coli in high yields. The monoclonal antibodies were screened for epitope specificity using recombinant truncated PIIICP. Several antibodies were identified which recognized different regions of the PIIICP molecule. The ability of the antibodies to detect PIIICP antigens in human cell line lysates and supernatants was demonstrated. As PIIICP antigens are a key marker of extracellular matrix metabolism, the monoclonal antibodies described here should be of value for clinical and basic research.

Quantification of the N-terminal propeptide of human procollagen type I (PINP): comparison of ELISA and RIA with respect to different molecular forms

This paper compares the results of procollagen type I N-terminal propeptide (PINP) quantification by radioimmunoassay (RIA) and enzyme linked immunosorbent assay (ELISA). PINP in serum from a patient with uremic hyperparathyroidism was measured in RIA and ELISA to 20 micrograms l-1 and 116 micrograms l-1 and the corresponding concentrations in dialysis fluid were 94.5 micrograms l-1 and 140 micrograms l-1, respectively. PINP antigen appears in two distinct peaks following size chromatography and the two peak fractions display immunological identity and identical M(r)'s (27 kDa: SDS-PAGE). Analysis of fractions from size separated amniotic fluid, serum and dialysis fluid demonstrated that the RIA failed to measure the low molecular weight form of PINP. However, the anti-PINP supplied with the RIA-kit and the anti-PINP applied in the ELISA reacted equally well with both molecular forms of PINP when analysed in a direct ELISA. It is concluded that the major difference in the ELISA and RIA results is due to assay efficacy with respect to the low molecular weight form of PINP.

Age-related changes in type-I collagen synthesis in human eyelid skin

PURPOSE

This study was to determine whether age-related decrements in type I collagen synthesis occur in human eyelid skin.

METHODS

Using an antibody to procollagen I, we investigated collagen synthetic activity in skin removed for cosmetic purposes from 10 white patients between the ages of 4 and 77 years. Eleven masked referees graded the immunostaining on a scale of 1 (most intense) to 10 (least intense).

RESULTS

The multiple range test for rank by group demonstrated more intense staining in younger patients compared with older patients. An average correlation coefficient of 0.8432 (p < 0.05) existed between each of the referee's rankings.

CONCLUSION

Type I collagen synthesis diminishes with age in eyelid skin.

Epidermolysis bullosa acquisita diagnosed by direct immunoelectron microscopy of the conjunctiva

OBJECTIVE

To describe for the first time the direct immunoelectron microscopic pattern of immune deposits on the conjunctival basement membrane in epidermolysis bullosa acquisita (EBA).

DESIGN

Case reports.

PARTICIPANTS

Two patients.

INTERVENTION

Epidermolysis bullosa acquisita associated with cicatrizing conjunctivitis.

MAIN OUTCOME MEASURES

Direct immunofluorescence and direct immunoelectron microscopy without freezing on conjunctival and skin biopsy specimens, indirect immunofluorescence, Western immunoblot analysis.

RESULTS

Results of direct immunoelectron microscopic examination of the conjunctiva showed the presence of immune deposits in the anchoring fibril zone, just beneath the lamina densa, in both patients. This finding was the same as the direct immunoelectron microscopic pattern shown in the skin of these patients, which is known to be very specific for EBA. Direct immunofluorescence was positive in the conjunctiva of only one patient. Indirect immunofluorescence and Western immunoblot analysis failed to detect circulating autoantibodies.

CONCLUSIONS

Direct immunoelectron microscopy on the conjunctiva is a useful diagnostic tool to differentiate EBA from other related autoimmune mucocutaneous blistering diseases.

Systemic therapy with estrogen or estrogen with progestin has no effect on skin collagen in postmenopausal women

OBJECTIVES

To investigate the effect of estrogen alone or combined with progestin on the amount and synthesis of skin collagen in postmenopausal women.

METHODS

Forty-three early postmenopausal women were enrolled into this open, non-randomized parallel-groups study. Fifteen women received a continuous oral dose of 2 mg of 17 beta-estradiol and 1 mg of norethisterone acetate daily and 14 women an oral dose of 2 mg estradiol valerate daily. Fourteen subjects served as controls. The histology and type I and III procollagen immunohistochemistry of the skin, skin thickness, the amount of total collagen determined by a colorimetric method and the synthesis of type I and III collagens determined by analysing procollagen propeptides in the suction blister fluid were studied before the treatment and at 6 and 12 months. The proportional area of elastic fibers and the thickness of the epidermis were assessed from the sections obtained before the treatment and at 12 months, with computerized image analysis.

RESULTS

Skin thickness, the amount and rate of collagen synthesis, the proportional area of elastic fibers and the thickness of the epidermis were not affected by either 17 beta-estradiol and 1 mg of norethisterone acetate or 2 mg of estradiol valerate. No histological or immunohistological changes were detected in the skin specimens during the 12-month treatment period compared to the baseline or to the skin specimens of the control group.

CONCLUSIONS

A 1-year treatment with systemic estrogen alone or combined with progestin does not change the amount of collagen or the rate of collagen synthesis in postmenopausal women.

Characterization of human type II procollagen and collagen-specific antibodies and their application to the study of human type II collagen processing and ultrastructure

Type II collagen is the most abundant collagen in articular cartilage and, together with other tissue-specific collagens and proteoglycans, provides the tissue with its shock-absorbing properties and its resiliency to stress. Specific antibodies which recognize various collagen types have been very useful in the study of collagen biosynthesis, structure and metabolism in normal and pathological conditions. Antibodies which recognize epitopes of type II collagen have been described previously; however, many of these antibodies display cross-reactivity with other collagens or with type II collagen from other species, reflecting the high degree of homology of the helical domains of fibrillar collagens. In this study, we prepared antibodies to sequential determinants of human type II procollagen employing synthetic peptides with sequences deduced from the nucleotide sequence of the human alpha 1 (II) procollagen cDNA. The antibodies were highly specific for epitopes in either the C-terminal propeptide or the telopeptide of the human type II collagen and did not cross-react with other human interstitial collagens or with murine type II collagen. These antibodies were used in conjunction with biosynthetic labeling to study the secretion and processing of human type II procollagen and collagen in human chondrocytes in vitro. The results indicated that a lag period of about 90 min was required for the secretion of newly synthesized type II procollagen. Conversion of the secreted procollagen into fully processed alpha-chains and their deposition in the cell layer were first apparent 240 min following the initiation of biosynthetic labeling. The antibodies were also used to examine, by immunoelectron microscopy, the structure of the extracellular matrix produced by human chondrocytes maintained in long-term cultures under conditions which permit the preservation of the cartilage-specific phenotype. These highly specific antibodies provide valuable tools to study the metabolism and structure of human type II procollagen and collagen in normal and pathologic conditions.

Human osteoclastoma-derived stromal cells: correlation of the ability to form mineralized nodules in vitro with formation of bone in vivo

It has been suggested that the stromal element of human osteoclastomas contains osteoblastic cells. In this study, we demonstrate that osteoclast-depleted, passaged stromal cells express alkaline phosphatase and osteocalcin in vitro and form mineralized nodules under appropriate culture conditions. In addition, we describe a model in which severe combined immunodeficient (SCID) mice were used to support the differentiation of these putative human osteoblast progenitors in vivo. Lesions formed from human stromal cells were identified using the OKa blood group antigen and human procollagen type I antibodies. By 21 days, the lesion was a complete bone unit: a fully mineralized cortex, remodeling trabeculae, and a highly cellular marrow space. Stromal cells derived from six out of seven osteoclastomas produced identical lesions. Further studies have demonstrated that the capacity of the osteoclastoma-derived stromal cells to form bone in vivo and in vitro is passage dependent; early passages were osteogenic in both model systems, while later passages were not. In conclusion, we have developed a model in which the osteogenic nature of cells can be confirmed in vivo. Furthermore, human osteoclastoma-derived stromal cells provide a source of these osteogenic cells to study human osteoblast differentiation, both in vivo and in vitro.

Maturation of collagen fibrils in the corneal stroma results in masking of tyrosine-rich region of type V procollagen

PURPOSE

To determine the molecular form of type V procollagen in collagen fibrils in mammalian corneal stromas.

METHODS

The presence of the tyrosine-rich region in the NH2-propeptide of type V procollagen in collagen fibrils was examined in human, bovine, and mouse corneas and human corneal fibroblast cultures by immunofluorescence microscopy and immunoblot analysis using a polyclonal antibody specific for this region. The antibody was generated using a glutathione S-transferase-fusion peptide.

RESULTS

The tyrosine-rich region was detected readily in frozen sections of 5- to 6-month-old mouse corneal stromas without the need for any unmasking techniques, indicating that this domain is exposed on the surface of striated collagen fibrils. In contrast, frozen sections of adult human and bovine corneas did not label with the polyclonal sera to the tyrosine-rich region. Immunoblot analysis of bacterial collagenase digests of human and bovine corneas, however, indicated that peptide fragments containing the tyrosine-rich region of type V procollagen and of the expected molecular weight of 70 to 85 kDa were present. Further immunofluorescence microscopic studies and immunoblot analysis of mouse corneas at different ages and of collagen fibrils formed in human corneal fibroblast cultures over time indicated that, initially, the tyrosine-rich region of type V procollagen could be detected in all these collagen fibrils; however, as the age of the mouse and the culture increased, the ability to detect this region decreased.

CONCLUSIONS

These results suggest that, in vivo, the tyrosine-rich region of type V procollagen is retained on type V procollagen molecules within mammalian collagen fibrils from corneal stromas and that this region becomes masked as collagen fibrils mature or the species ages.

Immunohistochemical localization of procollagen types I and III during placentation in pregnant rats by type-specific procollagen antibodies

To examine the sequential localizations of procollagen Types I (Pro I) and III (Pro III) during chorioallantoic placental formation in pregnant rats, we prepared polyclonal anti-rat Pro I- and III-specific antibodies. Biochemical analysis of a fraction containing [14C]-glycine-incorporated collagen from pregnant rat uteri showed that collagen Types I and III were actively synthesized during placental development. We examined 8-, 9.5-, 13-, and 20-day gestation rat uteri immunohistochemically. At Days 8 and 9.5, in the basal decidua facing the fetal cytotrophoblastic giant cell layer and implantation site, the immunoreactivity for Pro I was higher than that for Pro III. On Day 13, the enlarged myometrium and cytotrophoblastic cell layer showed increased immunoreactivity for Pro III. Unexpectedly, polygonal trophoblastic cells invading and modifying the maternal central artery showed intense immunoreactivity for Pro III. On Day 20, the fetal mesenchyme, large fetal blood vessels, and subendothelial stroma, including fetal blood capillaries, were more immunoreactive to Pro III antibody than to Pro I antibody in the labyrinth. Pro I and III synthesis and processing appear to be developmentally regulated and may be related to control of the microenvironment for supporting the fetus, control of the maternal blood supply stabilizing the fetoplacental physiological functions, and parturition.

Collagen-specific cytotoxic T lymphocyte responses in patients with ankylosing spondylitis and reactive arthritis

Both ankylosing spondylitis (AS) and reactive arthritis (ReA) are strongly associated with HLA-B27 although the mechanism for this association is still unknown. Here we examine the hypothesis that B27-restricted, joint antigen-specific cytotoxic T lymphocytes (CTL) may be the driving force of AS and ReA. Type II and type XI procollagens (CII and CXI, respectively), expressed almost exclusively in the articular cartilage of the joints, were chosen as the possible targets of autoimmune CTL. Type I procollagen (CI), expressed in many different tissues, was also included as control. Nineteen nonamer peptides bearing appropriate HLA-B27 binding motifs from human CI, CII and CXI were identified and synthesized. When analyzed for binding affinity to HLA-B27 in assembly assays, four (two from CII, two from CXI) were found capable of binding to HLA-B27 with high affinity. These B27-binding collagen peptides were then used to stimulate peripheral blood lymphocytes from eight B27-positive AS and three ReA patients for identification of possible B27-restricted autoimmune CTL. HLA-B27-restricted CTL specific for one of the CII peptides, P109 were found in one of the ReA patients, but in none of the others.

Serum concentration of procollagen type I carboxyterminal propeptide in systemic sclerosis

The serum level of procollagen type I carboxyterminal propeptide (P1CP), which has been used as an index of collagen synthesis in patients with various fibrotic diseases during the active stage, was measured using enzyme-linked immunosorbent assay in 61 patients with systemic sclerosis (SSc) and in 21 control subjects. The mean P1CP level in the SSc patients was significantly higher than in the normal controls (mean +/- SD, 326 +/- 319 vs 128 +/- 87 ng/ml; p < 0.005). In 36% of the SSc patients, the serum P1CP level was significantly elevated more than two standard deviations above the mean control value. The mean serum P1CP level in patients with diffuse SSc was significantly higher than in those with limited SSc (411 +/- 373 vs 255 +/- 199 ng/ml; p < 0.05). In addition, the SSc patients with elevated serum P1CP levels showed a significantly greater incidence of lung fibrosis and joint involvement than those with normal P1CP levels (p < 0.005 and p < 0.05, respectively). These results suggest that the serum P1CP level is a useful indicator of the severity of disease in SSc patients.

Heterogeneity of type III procollagen N-terminal peptides in BAL fluid from normal and fibrotic lungs

Levels of the N-terminal propeptide of type III collagen (PIIINP) in bronchoalveolar lavage fluid (BALF) are thought to reflect type III collagen production by the lungs, and increased levels have been reported in patients with pulmonary fibrosis. We wanted to know more about the relative proportions of these peptides in normal BALF, whether they altered in pulmonary fibrosis, and whether lymphoid tissue is capable of clearing PIIINPs. In this study, we used a radioimmunoassay which detects the different forms of PIIINP-related antigens with equal specificity, to measure PIIINPs in serum and BALF of patients with cryptogenic fibrosing alveolitis (CFA). To investigate why PIIINP profiles in BALF differed from serum, the absolute concentration and relative proportion of PIIINPs in lymph afferent and efferent to the popliteal lymph node of a sheep were also determined. PIIINP concentrations were significantly greater in serum and BALF of patients with CFA, compared with controls. Gel chromatography indicated that serum antigen distribution, both of patients and controls, contained approximately 20% Col 1-3; the remainder being Col 1. In contrast, BALF contained Col 1-3 and Col 1, together with an antigen of high molecular weight (> 150 kD). The relative proportion of each antigen varied quite widely, but there were no apparent differences between patients and controls. The concentration of PIIINPs in afferent lymph was 295 ng.ml-1 and in efferent lymph was 104 ng.ml-1. Gel chromatography demonstrated that a significant amount of Col 1-3, together with a high molecular weight peptide, had been cleared during passage through the node.(ABSTRACT TRUNCATED AT 250 WORDS)

Synthetic peptide-based immunoassay for amino-terminal propeptide of type I procollagen: application for evaluation of bone formation

Serum biochemical markers are powerful tools for the evaluation of bone turnover. In this study, we developed a radioimmunoassay, using a synthetic peptide for the N-terminal fragment of human type I [alpha 1(I)] procollagen (N-PCP). A 14-amino acid peptide was synthesized from the amino terminus and used to generate antibodies in rabbits. The synthetic peptide was used as standard and tracer in the assay. Both native type I amino procollagen (PINP), which was purified from skin fibroblasts, and human serum displaced tracer binding in parallel with the synthetic peptide. The range for measurement of N-PCP in serum was 0.7 to 30 micrograms/L (0.21-9.18 nmol/L). In a sample of 17 normal adults and 13 children (ages 9-16 years) there was a strong correlation between serum N-PCP determined by this assay and both skeletal alkaline phosphatase isoenzyme and osteocalcin, markers of bone formation. Serum concentrations of N-PCP in a group of normal children were eightfold higher than concentrations in normal adults, with no overlap between the two groups. N-PCP also correlated with C-terminal type I procollagen determined with a commercially available kit (r = 0.92).

A radioimmunoassay for the N-terminal propeptide of rat procollagen type III. Application to the study of the uptake of the N-terminal propeptide of procollagen type III in isolated perfused rat liver

Antibodies against a synthetic peptide representing the 14 C-terminal amino acids of the N-terminal propeptide of rat and bovine procollagen type III were raised in rabbits and used to develop a radioimmunoassay. N-Terminal propeptide of procollagen type III, purified from calf skin, served as standard and tracer material. The IC50 of the standard inhibition curve was 2.1 micrograms/l, the lower limit of detection about 0.4 microgram/l, interassay variation was 8.5% and the intraassay variation 6.6% in typical experiments. Three peaks of antigenicity were detected in rat serum after gel chromatography. One peak coeluted with purified N-terminal propeptide of procollagen type III, one peak contained material approximately twice this size, and one peak eluted close to the void volume of the column. The antigen concentration in rat serum decreased in an age dependent manner. Rat, bovine, sheep and minipig serum antigen was sufficiently crossreactive to allow the application of the assay to these species, whereas human, goat and guinea pig samples were not. The degradation product Col 1, causing non-parallel inhibition in commercially available assays for human samples was not recognized since it does not contain the epitope represented by the synthetic peptide. The assay was used to study the half-life of bovine and endogenous N-terminal propeptide of procollagen type III in isolated perfused rat liver. [125I]-labeled antigen was cleared rapidly from the perfusate (t1/2 less than 5 min). The bovine antigen was removed from the perfusate with a half-life of 15 +/- 4 min. Endogenous propeptide was perfused for 120 min with little change in concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Active collagen synthesis by pulmonary arteries in human primary pulmonary hypertension

Immunohistochemistry was performed on lung tissue obtained from patients with severe unexplained pulmonary hypertension using an antibody to the amino-terminal end of the procollagen type I propeptide. This antibody identifies newly synthesized alpha I(I) procollagen before cleavage of the amino-terminal propeptide following secretion and, therefore, can identify sites of active collagen deposition. Procollagen was detected in the media, media and neointima, or neointima alone of a large number of small muscular arteries from hypertensive lungs. Normal adult lungs were negative. Neointimal cells in remodeled small muscular arteries stained positively for alpha-smooth muscle actin and desmin consistent with a smooth muscle lineage. These data suggest smooth muscle-like cells in small muscular arteries are actively synthesizing collagen in patients with severe unexplained pulmonary hypertension.

Endothelial and fibroblastic activation in scleroderma. The myth of the "uninvolved skin"

We studied the immunohistochemistry of the skin of scleroderma patients to determine the differences (if any) between clinically "affected" and "nonaffected" areas. We examined paired skin biopsy samples from clinically involved forearm skin ("affected") and clinically uninvolved proximal skin ("nonaffected") taken from 19 patients with diffuse scleroderma and from 15 normal control subjects. We stained the sections with antibodies to endothelial leukocyte-adherence molecule type 1 (ELAM-1; to detect endothelial activation) and to procollagen-1 (PC-1; to detect newly formed, unprocessed collagen). There was increased expression of ELAM-1 and PC-1 in sclerodermatous skin as compared with the controls, but there was no difference between clinically affected and nonaffected skin samples. In 10 of 11 patients whose condition was getting worse, endothelial and fibroblast activation preceded fibrosis. Endothelial and fibroblast activation are more widespread in the skin of scleroderma patients than is evident by inspection on physical examination. What appears to be "normal" skin in diffuse scleroderma is already pathologic, as shown by abnormal endothelial activation and procollagen production.

Feedback regulation of collagen gene expression: a Trojan horse approach

The mechanisms involved in feedback regulation of type I procollagen synthesis by the N-terminal propeptide of the pro alpha 1(I) chain, termed Col 1, are poorly understood. We have constructed a metallothionein-human collagen chimeric minigene (pMTCol) that codes for a Col 1 fusion protein but lacks a signal peptide sequence and, therefore, would be expected to direct the synthesis of the fusion protein to the cytosol. Baby hamster kidney cells and fetal calf ligament cells, transfected with pMTCol, transcribed the gene and synthesized an intracellular antigen that was identified as the fusion protein with a monospecific antibody. Transfected fetal calf ligament fibroblasts showed significantly reduced levels of endogenously produced type I collagen, as determined by imaging and digital quantitation of immunofluorescence by confocal microscopy; synthesis of fibronectin, thrombospondin, and SPARC (secreted protein, acidic and rich in cysteine) was unchanged or increased in these cells. This recombinant approach offers the potential for a systematic analysis of feedback regulation of collagen synthesis.

Detection of procollagen biosynthesis using peptide-specific antibodies

Peptides corresponding to selected sequences of the alpha 1 chain of the COOH propeptide of type I and type III human procollagen were synthesized and used as antigens to develop polyclonal and monoclonal antibodies. The antibodies were shown to be epitope specific using a peptide-based solid phase enzyme-linked immunoadsorbent assay. The antibodies were specific for the appropriate procollagens and the COOH propeptides isolated from serum-free culture supernatants of human skin fibroblasts. The rabbit antisera directed to the type I synthetic peptide bound the intact procollagen molecule and both the procollagen alpha 1(I) and alpha 2(I) chains after the reduction of the disulfide bonds. In addition, the antisera bound intact type I COOH propeptide, generated by bacterial collagenase treatment of procollagen, and the individual chains of the propeptide after reduction. In contrast, a monoclonal antibody to the type I peptide was able to bind only to the reduced form of the COOH propeptide. Both rabbit polyclonal and murine monoclonal antibodies directed to the type III synthetic peptide bound the intact and the individual chains of type III procollagen as well as the intact and reduced forms of the type III COOH propeptide. The antibodies have been used to detect procollagen synthesis in two human osteosarcoma cell lines and the differential expression of procollagen in the culture medium of rat lung fibroblasts grown in the presence or absence of glucocorticoids.

Fibroblast markers in labial salivary gland biopsies in progressive systemic sclerosis

Labial salivary gland (LSG) biopsies from 13 patients were studied. Three were normal glands, five showed fibrosis induced by progressive systemic sclerosis (PSS) and five more had PSS-induced fibrosis combined with and focal sialadenitis compatible with Sjögren's syndrome (SS). Monoclonal antibodies to proline-4-hydroxylase (alpha PH or 5B5-A) and the carboxyterminal domain of human type I procollagen (alpha pC or M-38) were used as fibroblast markers. Immunostaining was done with avidin-biotin-peroxidase complex (ABC). Using various sample controls (including cultured fibroblasts and specimens enriched for lymphocytes, plasma cells, granulocytes, monocytes and dendritic cells) as well as analysis of various LSG resident cells, the specificity of the alpha PH and alpha pC markers for fibroblasts was established. Cross reactions were only seen with plasma cells and acinar cells containing the beta subunit of PH or disulfide isomerase involved in SS-SH interchange reactions in these secretory cells. All fibroblasts in fibroblast monolayer cultures at their logarithmic phase of growth stained with the fibroblast markers studied, but false negative staining was seen with resting, mature fibroblasts in dense connective tissue in LSG sections. Therefore, it can be concluded that proline 4-hydroxylase and the COOH-terminal domain of type-I procollagen both indicate fibroblast involvement in collagen (type l) synthesis and thus identify active but not resting fibroblasts. PH+ fibroblast-like cells and pC+ fibroblasts were both more frequent in PSS LSGs than in normal glands, suggesting active local fibroblast involvement in PSS.(ABSTRACT TRUNCATED AT 250 WORDS)

Hepatic and renal extraction of circulating type III procollagen amino-terminal propeptide and hyaluronan in pig

Hepatic and renal clearance of the amino-terminal propeptide of type III procollagen (PIIINP) and of the glycosaminoglycan, hyaluronan (HA) were investigated in a catheterization study of seven healthy anesthetized pigs. Two assays were used, in order to distinguish between the metabolism of different PIIINP-related antigens. One was the PIIINP RIA Kit, which measures the intact propeptide. The other was the PIIINP Fab assay, in which the antibody has an equal affinity to the intact propeptide and to smaller fragments, of which the latter constitutes most of the antigenic activity in serum. Hepatic and gastrointestinal extraction were evaluated from measurements of serum concentrations in the artery, the portal vein and the hepatic vein. We found a significant hepatic extraction of the intact propeptide (extraction ratio 0.14) and of HA (extraction ratio 0.23), but not of smaller PIIINP fragments. No gastrointestinal extraction of any of the tested substances could be demonstrated. Only smaller PIIINP fragments (such as the col 1 fragment) were extracted by the kidneys (the extraction ratio in the PIIINP Fab assay was 0.19). The renal extraction ratio of HA was 0.14. The amounts of PIIINP fragments and of HA extracted by the kidneys were 50- and 3-times the amounts found in urine, respectively, indicating that the col 1 fragment and HA are degraded in the kidneys in addition to urinary excretion. Our results suggest a dynamic turnover of connective tissue-related components with a fast catabolism of circulating components in liver and kidneys.

Low production of procollagen III by skin fibroblasts from patients with Ehlers-Danlos syndrome type IV is not caused by decreased levels of procollagen III mRNA

The Ehlers-Danlos syndrome type IV represents a heterogeneous group of diseases, the molecular defect of which seems to reside in a defective synthesis and processing of collagen III. Here we present data concerning both protein and mRNA levels of collagens I and III in cell cultures established from skin of nine patients and six controls. All patients investigated were characterized by a reduced amount of procollagen III in fibroblast cultures. However, the levels of collagen III propeptides, measured by a radioimmunoassay in culture medium of fibroblasts from the patients, were either decreased or in the range of control levels. Using hybridization with cDNA probes specific for pro alpha 1 (I) and pro alpha 1 (III) collagen chains we determined the ratios of procollagens I and III mRNA. Although synthesis of procollagen III was markedly reduced in fibroblasts of all patients studied, no parallel decrease of procollagen III specific mRNA was found. However, two distinctive groups of patients were identified, one with an unaltered ratio of procollagen I/III mRNA and the other which had an even higher proportion of collagen III mRNA.

Increased procollagen III aminoterminal peptide-related antigens and fibroblast growth signals in the lungs of patients with idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disorder characterized by an increased density of inflammatory cells, fibroblasts, and collagen within the lung parenchyma. To gain insights into the mechanisms leading to the increased density of fibroblasts and altered collagen metabolism in the IPF lung, bronchoalveolar lavage fluid from normal subjects and patients with IPF or sarcoidosis was analyzed for (1) the presence of antigenic material related to the aminoterminal propeptide domain of type III procollagen, and (2) fibroblast growth-promoting activity in the extracellular milieu of the lower respiratory tract. Whereas bronchoalveolar lavage fluid (BALF) type III procollagen aminoterminal peptide-related antigen levels in 59 patients with sarcoidosis were similar to the levels of control subjects (p greater than 0.10), 31 patients with IPF had markedly increased levels (12-fold over controls; p less than 0.025, IPF versus controls; p less than 0.01, IPF versus sarcoidosis). Type III procollagen aminoterminal peptide-related antigen levels correlated with an increase in the ability of BALF to stimulate fibroblast proliferation (p less than 0.05). Furthermore, BALF from patients with IPF markedly stimulated human lung fibroblast proliferation in vitro (199% increase, p less than 0.01), whereas lavage fluid from patients with sarcoidosis and from control subjects did not. The enhanced fibroblast proliferation induced by IPF BALF occurred in the absence of serum and exogenous growth factors, suggesting that both competence- and progression-type growth factors were present in the lavage fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidermolysis bullosa acquisita antigen is the globular carboxyl terminus of type VII procollagen

Epidermolysis bullosa acquisita (EBA) is a severe, chronic blistering disease of the skin. EBA patients have circulating and tissue-bound autoantibodies to a large (Mr = 290,000) macromolecule that is localized within the basement membrane zone between the epidermis and dermis of skin, the site of blister formation. The "EBA antigen" is known to be distinct from laminin, heparan sulfate proteoglycan, fibronectin, the bullous pemphigoid antigen, elastin, and collagen types I, II, III, IV, and V. Sera from patients with EBA, two monoclonal antibodies to the EBA antigen, and a monoclonal antibody to the carboxyl terminus of type VII procollagen identically label human amnion and skin by immunofluorescent and immunoelectron microscopy. Western immunoblots of the EBA antigen extracted from skin and of type VII procollagen labeled with the above sera and antibodies are identical. None of the sera or antibodies labels Western blots of pepsinized type VII collagen which is missing the globular amino and carboxyl terminal domains. These data show that the EBA antigen is the carboxyl terminus of type VII procollagen.

The aminoterminal propeptide of type III procollagen and basement membrane components in serum during wound healing in man

The aim of this study was to investigate if the serum concentrations of antigens related to basement membrane components and to the interstitial type III collagen reflect the sequential and transitional synthesis of basement membranes and of type III collagen in wound granulation tissue. The aminoterminal propeptide of type III collagen, the 7S domain of type IV collagen and the P1 fragment of laminin were determined in 11, 10 and 6 patients, respectively, during wound healing following intraabdominal surgery. No change was observed in the type III propeptide level at the first postoperative day. During further follow-up (mean 71 days, range 21-155 days), the propeptide levels showed a transitional increase, with a maximum at day 10. A sequential pattern was observed in the increase of the serum concentrations, as the maximum increase of the basement related antigens in serum occurred within the first 7 postoperative days. This is in accordance with observations of an early formation of basement membranes in blood vessels, preceding deposition of interstitial collagens in granulation tissue. The results support the assumption that the serum concentrations of connective tissue related antigens may be valuable markers of wound healing in man.

Functional heterogeneity of immune complexes in epidermolysis bullosa acquisita

Epidermolysis bullosa acquisita is an inflammatory subepidermal bullous disease characterized by circulating and tissue-bound complement-binding anti-basement membrane zone autoantibodies to type VII procollagen. Lesions are characterized by neutrophil-predominant inflammation in some patients, but not in others. These features suggest complement activation and generation of complement-derived chemotactic factors for leukocytes by basement membrane zone immune complexes may contribute to inflammation, but that complexes may be heterogeneous in the ability to express that function. In this study, we measured the ability of basement membrane zone complexes from patients with (n = 4) and without (n = 6) neutrophil predominant inflammation to activate complement and generate complement-derived chemotactic activity using a complement-dependent neutrophil attachment assay. The results showed considerable heterogeneity in neutrophil attachment among EBA patients and that both the incidence (4/4 vs 2/6) and magnitude (81 +/- 34 vs 12 +/- 10 neutrophils/mm basement membrane zone) of attachment were greater in patients with neutrophil-predominant inflammation. Functional heterogeneity appeared to be due to differences in the amounts of complement-activating complexes formed at the basement membrane zone, which in turn appeared to be due to differences in the availability of circulating complement-binding anti-basement membrane zone antibodies. This was suggested by a positive correlation (r = 0.72, p less than 0.01) between neutrophil attachment and complement-binding anti-basement membrane zone antibody titers and the observation that high levels of neutrophil attachment could be generated in skin from patients with epidermolysis bullosa acquisita who did not have neutrophil-predominant inflammation by treating their skin in vitro with complement-binding anti-basement membrane zone antibodies. These results suggest tissue complexes in epidermolysis bullosa acquisita are heterogeneous in the ability to activate complement and generate complement-derived chemotactins (C5a, C5a des arg), and that functional heterogeneity contributes to histologic heterogeneity. The functional immunologic-pathologic correlations observed in this study suggest epidermolysis bullosa acquisita is an autoimmune "collagen" disease.

Anchoring fibrils contain the carboxyl-terminal globular domain of type VII procollagen, but lack the amino-terminal globular domain

Type VII procollagen has been characterized as a product of epithelial cell lines. As secreted, it contains a large triple-helical domain terminated by a multi-globular-domained carboxyl terminus (NC-1), and a smaller amino-terminal globule (NC-2). The triple helix and the NC-1 domain have previously been identified in anchoring fibril-containing tissues by biochemical and immunochemical means, leading to the conclusion that type VII collagen is a major component of anchoring fibrils. In order to better characterize the tissue form of type VII collagen, we have produced a panel of monoclonal antibodies which recognize the NC-1 domain. Peptide mapping of these epitopes indicate that they are independent and span approximately 125,000 kDa of the total 150,000 kDa of each alpha chain contained in NC-1. All these antibodies elicit immunofluorescent staining of the basement membrane zone in tissues. Type VII collagen has been extracted from tissues. As previously reported, it is smaller than type VII procollagen, (Woodley, D. T., Burgeson, R. E., Lunstrum, G. P., Bruckner-Tuderman, L., and Briggaman, R. A., submitted for publication), and we now find that it predominantly occurs as a dimer. Following clostridial collagenase digestion, intact NC-1 has been recognized, indicating that the difference in apparent Mr between the tissue form of the molecule and type VII procollagen results from modification of the amino terminus. The size of the amino-terminal globule has been determined to be between approximately 96 and 102 kDa. Rotary shadowing analyses of extracted molecules indicate that dimeric molecules contain the NC-1 domain, but are missing intact NC-2. We propose that the tissue form monomer, Mr = 960,000, be referred to as "type VII collagen." These studies strongly suggest that anchoring fibrils contain dimeric molecules with intact NC-1 domains. The data also support the previous suggestion that the NC-2 domain is involved in the formation of disulfide bond-stabilized type VII collagen dimers, and is subsequently removed by physiological proteolytic processing.

Production of monoclonal antibodies recognising N-ethylmaleimide during attempted generation of monoclonal antibodies to human type I procollagen

Mice were immunised for the production of monoclonal antibodies to human procollagen (I) using antigen purified from fibroblast conditioned medium. The procedure for procollagen (I) preparation included the addition of proteinase inhibitors N-ethylmaleimide, phenylmethylsulphonyl fluoride and ethylenediaminetetraacetic acid to prevent damage by proteolytic cleavage. Four of the five monoclonal antibodies subsequently produced were found to recognise the thiol proteinase inhibitor N-ethylmaleimide but not type I procollagen prepared in the absence of N-ethylmaleimide. One of these monoclonal antibodies was examined further and shown to recognise beta-galactosidase after it had been reacted with N-ethylmaleimide. As far as we are aware this is the first time that monoclonal antibodies have been produced which recognise N-ethylmaleimide. Our findings indicate an unexpected reaction between procollagen and N-ethylmaleimide and prompt the suggestion that the use of N-ethylmaleimide in the purification of procollagen and other proteins should be reexamined.

Collagen synthesis by cell lines derived from Mov-13 mouse embryos which have a lethal mutation in the collagen alpha 1(I) gene

Mouse embryos homozygous for the Mov-13 mutation produce no collagen I, owing to transcriptional blockage of the collagen alpha 1(I) gene by a retroviral insert. Fibroblast-like cell lines derived from these embryos were compared with similar lines derived from heterozygous and wild-type embryos with respect to the total amounts, and types, of collagen synthesized. Total collagen synthesized by either cloned or uncloned cell lines correlated with their genotype, demonstrating no compensation for absence of collagen I production by an increase in synthesis of other collagen types. Procollagen alpha 2(I) chains were not detected in the homozygous cell lines, demonstrating that these chains do not form homotrimers, nor do they form heterotrimers with alpha-chains of other collagen types. Procollagen III levels were quantified by radioimmunoassay and found to be similar in all cell lines.

Immunohistochemical distribution of collagens types IV, V, and VI and of pro-collagens types I and III in human alveolar bone and dentine

The aim of the present study was to characterize the composition of the organic matrix in alveolar jaw bone and dentine using antibodies against pro-collagens Types I and III and collagens Types IV, V, and VI. After demineralization of oral hard tissues in 0.2 N HCl, antigenicity was well preserved and the distribution of the pro-collagens and collagens could be demonstrated. Staining for pro-collagen Type I was prominent around osteoblasts and in pre-dentine, indicating active de novo synthesis of Type I pro-collagen. Pro-collagen Type I was ubiquitous but was less abundant in bone and dentine, whereas pro-collagen Type III was seen only in areas of bone remodeling, in peritubular spaces, and in pre-dentine. Type IV collagen was limited to the basement membranes of vessels in osteons and bone marrow. Type V collagen was detected neither in pre-dentine nor in bone. In contrast, Type VI collagen was found in dentine and bone, showing a faint but homogeneous staining which, similarly to pro-collagen Type III, was pronounced around osteoblasts and in pre-dentine, areas of active bone and dentine formation. This study showed that the organic matrix of dentine and bone contains Type VI as well as Type I collagen. Pro-collagen Type III (and to a lesser extent collagen Type VI) is transiently produced during new formation and remodeling of oral hard tissues, and disappears once the matrix calcifies. Type I pro-collagen qualifies as a general marker protein for increased osteoblastic activity. We conclude that immunostaining for the different collagen/pro-collagen types can be used to assess normal or abnormal stages of bone/dentine formation.

Collagen immunotyping of the hepatic fibrosis in human alveolar echinococcosis

An extremely dense fibrosis is responsible for the main complications of alveolar echinococcosis (AE), a severe parasitic disease due to the development in the liver of a larval form of the cestode Echinococcus multilocularis. Immunotyping of collagens present in fibrous, granulomatous, and normal areas of the liver was performed in nine patients with AE. Immunofluorescent labelling of collagen types showed that dense fibrosis was entirely composed of thick bundles of type I and type III collagens, surrounding old parasitic vesicles with an autofluorescent laminated layer. In granulomatous areas, collagens were labelled as clusters consisting mainly of type III procollagen and collagen. Concentric bundles of type III collagen surrounded active parasitic vesicles. An enhancement of the normal labelling in portal spaces of the intact liver was present in all the patients. These results suggest that irreversible acellular keloid scar-like fibrosis observed in AE is the ultimate result of cytotoxic and fibrogenetic events related to the immune response of the host which are taking place initially in the granulomatous area surrounding the young parasite larvae.

Immunolocalization of type III collagen and procollagen in cirrhotic human liver using monoclonal antibodies

Immunolocalization of type III collagen and procollagen in cirrhotic human liver was studied using monoclonal antibody specific for the helical determinant of type III collagen extracted from human placenta. Deparaffinized, trypsin-treated cirrhotic liver sections from 8 autopsy cases were examined by the unlabeled peroxidase-antiperoxidase and immunofluorescence techniques. These techniques revealed the localization of this epitope shared by type III collagen and procollagen not only in the extracellular matrix of hepatocytes and sinusoidal cells but also in the cytoplasm. In hepatocellular carcinoma concurrent with cirrhosis, neoplastic cells were shown to react with this antibody as well. These results are consistent with data obtained using antiserum specific for bovine type III procollagen aminopeptide which appeared in our previous report.