Leila Risteli

Serum Concentrations of the Type I and III Procollagen Propeptides as Biochemical Markers of Growth Velocity in Healthy Infants and Children and in Children with Growth Disorders

ABSTRACT: The reproducibility and specificity of a new, rapid, simple RIA for measuring the concentration of the soluble carboxypropeptide of type I procollagen (PICP) in serum was confirmed. Serum PICP was determined in 442 healthy Caucasian subjects ranging in age from 3 wk to 18 y. Highest PICP values (mean ± SD: 2200 ± 350 μg/L) occurred in infants less than 3 mo of age, falling by 70% at 2 y and by an additional 10% at 4 y. There was no significant change in serum PICP between 4 and 16 y of age (330 ± 130 μg/L), but a decrease to adult levels of <160 μg/L, occurred by 18 y. In 76 children with growth disorders, serum PICP was related to linear growth velocity (p < 0.001), although there were no significant differences in PICP among the 38 children with growth hormone insufficiency, the 21 short children with no endocrinologic abnormality, or the 17 tall children. All 15 prepubertal children treated with growth hormone for 3 mo showed significant increases in both growth velocity and serum PICP, with a significant relationship (p < 0.01) between the degree of increases. The rise in serum PICP at 3 mo (but not baseline PICP values) predicted the increase in growth velocity after 1 y of treatment. Similar changes were observed in the concentration of the aminopropeptide of type III procollagen, except that serum aminopropeptide of type III procollagen showed a definite increase during puberty and a wider spread of values in growth disorders. We conclude that measuring serum PICP by the new, reproducible assay reflects height velocity in prepubertal children and may be a useful biochemical means of monitoring growth rates.

Synthesis of type I collagen in healing wounds in humans

To quantify wound healing in surgical patients, samples of wound fluid were collected through a silicone rubber tube for 7 postoperative days and their concentrations of the carboxyterminal propeptide of type I procollagen (PICP) and the aminoterminal propeptide of type III procollagen (PIIINP) were measured with specific radioimmunoassays. The mean concentration of PICP in would fluid on day 1 was 207 +/- 92 (SD) micrograms/L, and on day 2 908 +/- 469 micrograms/L (p less than 0.001, signed rank test). On day 7, the mean concentration reached was 380 times higher than that of day 1 (79,330 +/- 54,151 micrograms/L). Only one peak of PICP antigenicity, corresponding to the intact propeptide as set free during synthesis of type I procollagen, was detected on Sephacryl S-300 gel filtration analysis of wound fluid samples. The mean concentration of PIIINP was 70 +/- 61 micrograms/L on day 1, 86 +/- 88 micrograms/L on day 2, and 180 +/- 129 micrograms/L on day 3 (p less than 0.001 when compared with day 1). Finally on day 7, a 250-fold concentration (17,812 +/- 9839 micrograms/L), compared with day 1, was reached. Methods described in the present paper allow separate and repetitive quantification of the synthesis of both type I and type III procollagen during human wound healing.

Collagen metabolism and growth in prepubertal children with asthma treated with inhaled steroids

OBJECTIVE To investigate growth and markers of collagen and bone metabolism in prepubertal children with asthma. STUDY DESIGN We measured growth velocity over 12 months and markers of collagen types I and III synthesis (PINP, PICP, PIIINP), collagen type I degradation (ICTP), and bone metabolism (bone-specific alkaline phosphatase and osteocalcin) on one occasion in 56 prepubertal children with stable asthma, 39 of whom were treated with inhaled budesonide or beclomethasone. Collagen data were compared with normal control values. RESULTS Children treated with inhaled steroids had reduced collagen synthesis (PINP, PIIINP) compared with control subjects (p = 0.038, p = 0.045), although PICP was increased (p = 0.05). Carboxyterminal telopeptide of type I collagen was reduced in patients treated with inhaled steroids (p < 0.0005) compared with nonsteroid-treated patients. Serum osteocalcin but not bone-specific alkaline phosphatase was significantly reduced in children treated with inhaled steroids (p < 0.02). Significant correlation was observed between PIIINP and ICTP and growth velocity. CONCLUSION Collagen turnover is reduced in children with asthma receiving long-term inhaled steroid treatment. Markers of collagen synthesis provide a more accurate reflection of growth disturbance than osteocalcin and bone-specific alkaline phosphatase.

Aminoterminal propeptide of type III procollagen in healing wound in humans.

For quantitative analysis of wound healing in surgical patients, samples of wound fluid were collected through a silicone rubber tube and their concentration of the aminoterminal propeptide of type III procollagen was measured with a specific radioimmunoassay. Peritoneal fluid, collected through an abdominal drain, and serum were also analyzed. At day 1 after operation, the mean concentration of the propeptide was 30 times higher than the mean preoperative serum level (2.5 micrograms/L). A significant increase (p less than 0.001) occurred at day 3 in the wound and at day 2 in peritoneal fluid. At day 5 the mean wound concentration (2670 micrograms/L) was 1000 times higher than the serum level. In serum a small but significant increase (p less than 0.05) was found at days 5 and 30. The increase in wound fluid resulted from the intact, liberated propeptide, indicating that the results reflect the synthesis of type III collagen deposited in the wound. This procedure offers a quantitative tool for wound healing studies. Other extracellular matrix components can also be measured, the sequential pattern of their appearance can thus be assessed, and disturbances and treatment effects in wound healing can be detected.

Basal lamina glycoproteins laminin and type IV collagen are assembled into a fine-fibered matrix in cultures of a teratocarcinoma-derived endodermal cell line.

Abstract Extracellular matrix glycoproteins synthesized and deposited by a mouse teratocarcinoma-derived endodermal cell line (PYS-2) in culture were analysed by metabolic labelling and immunochemical methods, and the matrix structure was studied by immunofluorescence and electron microscopy. PYS-2 cells secreted two major high-molecular weight glycoproteins, laminin and type IV collagen, which were deposited in apparently unprocessed form under the cells into a lamellar matrix composed of a loose network of fine fibrils and attached dense grains. The cells did not synthesize detectable amounts of fibronectin, but the matrix was found to bind fibronectin from the culture medium. The matrix structure was sensitive to bacterial collagenase indicating a role for type IV collagen in matrix integrity. The PYS-2 matrix which contains defined basal lamina glycoproteins provides possibilities for in vitro studies on the organization of deposited basal lamina components.

Immunohistochemical evidence that lung carcinomas grow on alveolar basement membranes

We studied 28 lung carcinomas representing different histological types and three of their regional lymph node metastases immunohistochemically by using specific antibodies against two basement membrane proteins—the 7S domain of type IV collagen and the PI fragment of laminin. One feature common to all peripherally growing tumors. regardless of the histologic type, was an intact basement membrane between the tumor and the unaffected lung tissue. At these locations, the basement membrane was organized into alveolar structures that did not differ from normal lung tissue. The fibrotic central areas of the tumors did not exhibit this phenomenon. Based on these findings. we believe that malignant tumors of the lung utilize preserved alveolar basement membranes for their local spread. This finding seems to represent a general property of all lung carcinomas, not only adenocarcinomas of the bronchiolo-alveolar type.

Assays of type I procollagen domains and collagen fragments: Problems to be solved and future trends

The biochemical possibilities for developing specific assays for type I collagen metabolism are described. Type I collagen synthesis can be assessed either by the analysis of the carboxyterminal or aminoterminal propeptides, which are in principle produced in a molar ratio of 1:1. However, in clinical situations altered behaviour can be found, the reasons for which may be altered clearance or even the existence of variant forms of type I collagen. Type I collagen degradation can be specifically detected by analysis of either cross-linked carboxy- or aminoterminal telopeptides or by the cross-links themselves liberated during the degradation processes. The heterogeneity of the cross-links and the constituent chains of the cross-linked peptides in different tissues and possibly in different clinical situations introduce problems, which should be studied and resolved in the future.

Prognostic value of serum hyaluronic acid and type I and III procollagen propeptides in extrahepatic biliary atresia.

Although portoenterostomy has greatly improved the prognosis of extrahepatic biliary atresia (EHBA), 10-20% of patients still die before 5 y of age, and the only treatment option is liver transplantation (LT). To investigate whether these patients may be identified at an early stage, when the chances of successful LT are optimal, we have measured serum concentrations of hyaluronic acid (HA), the amino-terminal propeptide of type III procollagen (PIIINP) and the carboxy-terminal and amino-terminal propeptides of type I procollagen (PICP, PINP) in 24 selected patients with EHBA, both before portoenterostomy and then every 6 mo until death (n = 10, age at death = 7-20 mo), LT (n= 6, age at LT = 1.1-4.8 y) or 5 y of age (n= 8). Raised serum HA above 200 μg/L before portoenterostomy identified those patients who would die or require LT in the first 5 y of life with a positive predictive value of 88%; after portoenterostomy, longitudinal changes in HA reflected clinical status in each patient. None of the other three markers was of prognostic value, and only PIIINP showed any relationship with clinical status, and then only up to 1.5 y. Interestingly, PINP (but not PICP) tended to be low in all patients before portoenterostomy and may reflect impaired bone collagen metabolism during early skeletal changes in EHBA. This study therefore suggests that measurement of serum HA may be a useful complementary test in EHBA, particularly in identifying, at an early stage, those patients who should be considered for LT.

Preferential hydroxylation of type IV collagen by lysyl hydroxylase from Ehlers-Danlos syndrome type VI fibroblasts

Abstract Normal and Ehlers-Danlos syndrome type VI human skin and cornea fibroblasts were assayed for lysyl hydroxylase activity using two different collagen types as substrates. The enzyme from normal fibroblasts hydroxylated type I collagen more readily than type IV collagen. In the diseased cells the enzyme activity was significantly reduced, and the residual activity was preferentially directed towards type IV collagen. This suggests the existence of isoenzymes of lysyl hydroxylase or an alteration in the Ehlers-Danlos syndrome type VI that affects the binding of type I collagen more than that of type IV collagen.

Collagen synthesis in intact skin is suppressed during wound healing.

OBJECTIVE Simultaneous monitoring of total collagen synthesis as well as synthesis in intact skin and in the wound to verify the higher priority of wound healing after surgery. SUMMARY BACKGROUND DATA Synthesis of acute phase proteins is stimulated by surgical trauma. At the same time, production of albumin is inhibited and there is a net catabolism of skeletal muscle proteins. Similarly, the authors have found a transient inhibition of total collagen synthesis after surgery. The authors hypothesized a lower priority in synthesis of structural and peripheral collagen for the benefit of wound healing. METHODS The concentrations of the carboxyterminal propeptide of type I procollagen (PICP) and the aminoterminal propeptide of type III procollagen (PIIINP) were measured in suction blister fluid of intact skin and in wound fluid in ten surgical patients. PICP and PIIINP concentrations in serum were also measured. Specific radioimmunoassays were used. RESULTS In peripheral skin, the median preoperative concentrations of PICP and PIIINP were 228 and 140 micrograms/L, respectively. On postoperative days 1, 2, 4 and 7, the median concentration of PICP was 145 (p = 0.01, Wilcoxon signed rank sum test), 102 (0.02), 159 (0.03), and 152 (0.06) micrograms/L, respectively. The postoperative medians of PIIINP were 68 (p = 0.17), 76 (0.04), 66 (0.06), and 56 (0.03) micrograms/L, respectively. At the same time, collagen synthesis in the wound increased dramatically from the second day on. After an initial decrease, propeptide concentrations in serum gradually increased from the fourth day on. CONCLUSIONS Collagen synthesis is regulated for the benefit of the wound during the acute phase response.