Separate and Combined Effects of GIP and GLP-1 Infusions on Bone Metabolism in Overweight Men Without Diabetes

CONTEXT

The gut-derived incretin hormones glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1) have been suggested to play a role in bone metabolism. Exogenous administration of GIP inhibits bone resorption, but the effect of GLP-1 is less clear. Furthermore, the combined effect of exogenous GIP and GLP-1 on bone metabolism is unknown.

OBJECTIVE

To investigate the effect of separate and combined infusions of the incretin hormones GIP and GLP-1 on bone resorption and formation.

DESIGN

Randomized, double-blinded, placebo-controlled, crossover study including five study days.

PARTICIPANTS

Seventeen overweight/obese men.

INTERVENTIONS

On the first study day, a 50-g oral glucose tolerance test (OGTT) was performed. On the next four study days, isoglycemic IV glucose infusions (IIGI), mimicking the glucose excursions from the OGTT, were performed with concomitant infusions of GIP (4 pmol/kg/min), GLP-1 (1 pmol/kg/min), GIP+GLP-1 (4 and 1 pmol/kg/min, respectively), or placebo, respectively.

PRIMARY OUTCOMES

Changes in bone resorption assessed by measurements of carboxy-terminal type I collagen crosslinks (CTX) and in bone formation as assessed by procollagen type 1 N-terminal propeptide (P1NP) concentrations.

RESULTS

During the OGTT, CTX was significantly lowered by 54 ± 13% from baseline (mean ± SD) compared with 28 ± 12% during IIGI + saline (P < 0.0001). During IIGI+GLP-1 and IIGI+GIP, CTX was lowered by 65 ± 16% and 74 ± 9%, respectively, from baseline, whereas IGII+GIP+GLP-1 lowered CTX by 84 ± 4% from baseline. P1NP levels were unaffected by the interventions.

CONCLUSIONS

Our data suggest that GLP-1, like GIP, may be involved in regulation of bone resorption and that GIP and GLP-1 together have partially additive inhibitory effects.

Does metformin treatment influence bone formation in patients with nonalcoholic fatty liver disease?

Antidiabetic drug metformin that improves insulin sensitivity and used in the treatment of nonalcoholic fatty liver disease (NAFLD), may affect the bone health. Our study was designed to investigate a possible effect of metformin on bone formation marker, procollagen type I N-terminal propeptide (P1NP) in patients with NAFLD.In a randomized, placebo controlled study, 63 patients with NAFLD were assigned to one of 2 groups: Group 1 received daily metformin and Group 2 received placebo. Metabolic parameters, insulin resistance markers, and P1NP were determined.Although circulating P1NP levels did not differ significantly between the groups at baseline, at the end of the study, P1NP was significantly lower in patients treated with metformin than in the placebo group (p<0.007). Within-group analysis indicated that P1NP levels significantly decreased (p=0.023) in patients receiving metformin during 4-month follow-up period, while no change in P1NP was observed in placebo group (p=0.359). In general linear model metformin treatment was the only significant independent predictor of endpoint P1NP.Metformin treatment was associated with decrease in P1NP levels in patients with NAFLD. The effect on P1NP was independent of glucose lowering effect and caused from exposure to metformin per se.

Biochemical markers of bone turnover in diabetes patients--a meta-analysis, and a methodological study on the effects of glucose on bone markers

This study examined whether markers of bone turnover differ between individuals with and without diabetes. Bone markers showed heterogeneity between studies and were discrepant for markers of bone creation and markers of bone degradation. Bone markers may be of lesser value in diabetes due to heterogeneity.

INTRODUCTION

The aim of this meta-analysis was to compare existing literature regarding changes in bone markers among diabetics compared to healthy controls. To exclude that blood glucose levels among diabetes patients could influence the assays used for determining bone turnover markers, a methodological study was performed.

METHODS

Medline at Pubmed Embase, Cinahl, Svemed+, Cochrane library, and Bibliotek.dk was searched in August 2012. The studies should examine biochemical bone turnover among diabetes patients in comparison to controls in an observational design. In the methodological study, fasting blood samples were drawn from two individuals. Glucose was added to the blood samples in different concentrations and OC, CTX, and procollagen type 1 amino terminal propeptide were measured after 0, 1, 2, and 3 h.

RESULTS

Twenty-two papers fulfilled the criteria for the meta-analysis. From the pooled data in the meta-analysis, the bone markers osteocalcin (OC) (-1.15 ng/ml [-1.78,-0.52]) and C-terminal cross-linked telopeptide (CTX) (-0.14 ng/ml [-0.22, -0.05]) were significantly lower among diabetes patients than non-diabetes patients, however other markers did not differ. All markers displayed very high heterogeneity by I2 statistics. In the methodological study, the addition of glucose did not significantly change the bone markers neither by level of glucose nor with increasing incubation time.

CONCLUSION

The dissociative pattern of biochemical bone markers of bone formation and bone resorption present in diabetes patients is thus not caused by glucose per se but may be modulated by unknown factors associated with diabetes mellitus.

Growth hormone substitution in growth hormone-deficient adults: effects on collagen type I synthesis and skin thickness

Growth hormone stimulates collagen type I synthesis. Collagen type I is a common matrix compound in a large number of connective tissues. The aim of our study was to prove whether a stimulation of collagen type I synthesis might be accompanied by a deposition of collagen type I in the skin (cutis). Twenty growth hormone-deficient hypopituitary patients were included in a randomised, double-blind, placebo controlled, prospective, twelve-month study (eighteen patients assessable at the end of the study). The patients were treated with recombinant human growth hormone 0.25 U/kg/week subdivided in daily subcutaneous injections beginning with half the dosage during the first four weeks. During the first six months half of the patients were treated with placebo. PICP, the indicator of collagen type I synthesis, was increased after six months of therapy when compared to placebo. Skin thickness measured by ultrasound at the forearm and mechanically at the dorsum of the hand with strong compression of the skin both increased significantly following growth hormone substitution. Our data indicate that the stimulation of collagen type I synthesis by growth hormone substitution is followed by a deposition of collagen type I in the skin.

Bone turnover markers as predictive tools for skeletal complications in men with metastatic prostate cancer treated with zoledronic acid

BACKGROUND

Bone turnover markers are helpful to diagnose bone metastases. The aim of this study was to evaluate the usefulness of these markers in prostate cancer patients with bone metastases before and during the treatment with zoledronic acid as predictive and monitoring tools of skeletal-related events (SRE).

METHODS

One hundred seventeen prostate cancer patients with bone metastases and treated with zoledronic acid (4 mg every 4 weeks) were examined. Fifty-six patients were with and 61 patients without SRE during a 60-week study. Total and bone-specific alkaline phosphatase, and amino-terminal procollagen propeptides of type-I-collagen (PINP), cross-linked N-terminal (NTx), cross-linked C-terminal telopeptides of type-I-collagen (ICTP), and C-terminal telopeptides of type-I-collagen as well as prostate-specific antigen (PSA) were measured before and 12, 24, 36, 48, and 60 weeks after starting treatment.

RESULTS

Higher baseline concentrations were observed in the SRE group. The bone markers except for ICTP and tALP decreased to 20-80% of the baseline values at week 12 after the drug administration showing a generally higher decline in the non-SRE group except for NTx. At all time points during treatment higher and increasing concentrations of bone markers were observed in the SRE group compared with non-SRE group. Cox regression models with clinical data and bone markers showed the baseline NTx concentration as predictor of SREs. During the study, percentage changes of PINP and ICTP were most indicative for SREs.

CONCLUSIONS

Bone markers are useful tools to predict and diagnose SRE in prostate cancer patients with bone metastases under receiving zoledronic acid therapy.

Amla (Emblica officinalis Gaertn.) extract promotes procollagen production and inhibits matrix metalloproteinase-1 in human skin fibroblasts

AIM OF THE STUDY

Emblica officinalis Gaertn., commonly known as amla, is a rich dietary source of vitamin C, minerals and amino acids, and also contains various phenolic compounds. Amla extract is also known to exhibits potent antioxidant properties and to provide protection for human dermal fibroblasts against oxidative stress, and therefore it is thought to be useful for natural skin care. In this study, we investigated the effects of amla extract on human skin fibroblasts, especially for production of procollagen and matrix metalloproteinases (MMPs), in vitro.

MATERIALS AND METHODS

Mitochondrial activity of human skin fibroblasts were measured by WST-8 assay. Quantification of procollagen, MMPs, and Tissue inhibitor of metalloproteinase-1 (TIMP-1) released from human skin fibroblasts were performed by immunoassay technique.

RESULTS AND CONCLUSIONS

Amla extract stimulated proliferation of fibroblasts in a concentration-dependent manner, and also induced production of procollagen in a concentration- and time-dependent manner. Conversely, MMP-1 production from fibroblasts was dramatically decreased, but there was no evident effect on MMP-2. TIMP-1 was significantly increased by amla extract. From these results, it appears that amla extract works effectively in mitigative, therapeutic and cosmetic applications through control of collagen metabolism.

Effects of etanercept on serum biochemical markers of cartilage metabolism in patients with spondyloarthropathy

OBJECTIVE

Anti-tumor necrosis factor (TNF) therapies provide symptomatic benefit in patients with spondyloarthropathy (SpA). Their effect on structural lesions has not yet been assessed. Biochemical markers of cartilage turnover revealing type II collagen degradation and synthesis are associated with joint damage in rheumatoid arthritis; their role in SpA is unknown. We describe the effects of etanercept on biochemical markers of type II collagen synthesis and degradation in patients with SpA followed for 2 years.

METHODS

A total of 29 patients with SpA aged 22-68 years were included in a prospective 2-year study. Each patient received etanercept (25 mg twice a week) because of active disease despite optimal treatment. Cartilage degradation was investigated by measuring serum levels of the type II collagen fragments Helix-II and C2C, whereas the C-terminal propeptide of type II collagen (PIICP) was used as a marker of type II collagen synthesis. These markers were measured at baseline and after 1, 3, 6, 12, and 24 months of treatment.

RESULTS

Over 2 years, there was a significant decrease of serum C2C (p = 0.0035 by repeated Friedman's test) and serum Helix-II (p = 0.004). Compared to baseline, the decrease of serum C2C was significant at Month 12 (-12.1%; p = 0.004), whereas the decrease of serum Helix-II was observed as early as 1 month (-18.1%; p = 0.015) after start of therapy, reaching a maximum decrease of -33.4% (p = 0.0079) at Month 12. Conversely, PIICP increased significantly by 17% (p = 0.006) at 24 months.

CONCLUSION

These data suggest that etanercept may have beneficial effects on cartilage metabolism in patients with SpA.

The effect of prior bisphosphonate exposure on the treatment response to teriparatide in clinical practice

Our objective was to determine the effect of prior bisphosphonate exposure on the treatment response to teriparatide. All patients started on teriparatide in our hospital are entered into a database. All patients who had at least 12 months' treatment were identified. Patients were divided into two groups depending on whether or not they had prior bisphosphonate exposure, and the response to teriparatide was compared using procollagen of type 1 N-terminal propeptide (P1NP) and bone mineral density (BMD). Fifty-two patients had been treated for at least 12 months, 38 with prior bisphosphonate exposure and 14 without. The mean duration of bisphosphonate treatment was 67 months, discontinued a mean of 1 month previously. P1NP increased significantly at 3 and 6 months in both groups. However, those without previous bisphosphonate treatment had a higher baseline P1NP (49 vs. 30 microg/L, P<0.01), and this remained higher at 3 months (109 vs. 71 microg/L, P=0.10) and 6 months (183 vs. 126 microg/L, P=0.06), although the difference was not significant. In the prior bisphosphonate and bisphosphonate naive groups, respectively, the change in spinal BMD was 9.0% and 7.8% (P=0.54) at 12 months and 9.8% and 6.1% (P=0.30) at 18 months. The respective change in hip BMD was 1.0% and -0.3% (P=0.36) at 12 months and 2.8% and 1.3% (P=0.44) at 18 months. There was a trend toward a smaller but still significant increase in P1NP in response to teriparatide in bisphosphonate-treated patients. Although this suggests a blunting of the anabolic effects, in our clinic population this did not result in a reduction in BMD gain.

Effects of hyaluronan on cell proliferation and mRNA expression of procollagens alpha 1 (I) and alpha 1 (III) in tendon-derived fibroblasts from patients with rotator cuff disease: an in vitro study

BACKGROUND

Hyaluronan (HA) improves postoperative recovery after flexor tendon surgery, preventing postoperative adhesion. However, its influence on the rotator cuff tendon after cuff repair has not yet been clarified in detail.

HYPOTHESIS

Hyaluronan is likely to modulate cell proliferation and mRNA expression of procollagens alpha1 (I) and alpha1 (III) in tendon-derived fibroblasts in patients with rotator cuff disease.

STUDY DESIGN

Controlled laboratory study.

METHODS

The study subjects were 10 patients with rotator cuff disease, with an average age of 62 years (range, 44-72). Various concentrations of HA (1.0-5.0 mg/mL) were added to monolayer-cultured tendon-derived fibroblasts from these patients. Hyaluronan binding and CD44 expression on the tendon-derived fibroblasts were evaluated by confocal microscopy using fluorescein-conjugated HA and antihuman CD44 antibody (OS/37). Cell proliferation was evaluated by recording changes in cell number. The levels of expression of procollagen alpha1 (I) and alpha1 (III) mRNA were measured by real-time reverse transcriptase polymerase chain reaction.

RESULTS

Immunofluorescence cytochemistry detected constitutive binding of HA and CD44 expression on the tendon-derived cells. Treatment with various concentrations of HA significantly inhibited cell proliferation and decreased the expression level of procollagen alpha1 (III) mRNA, but not that of procollagen alpha1 (I) mRNA, in the tendon-derived fibroblasts.

CONCLUSION

Hyaluronan modulates cell proliferation and the expression level of procollagen alpha1 (III) mRNA, but not that of pro-collagen alpha1 (I), in fibroblasts from patients with rotator cuff disease.

CLINICAL RELEVANCE

Postoperative use of exogenous HA may allow the healing of a repaired rotator cuff tendon with minimal adhesion.

Leukotriene D4 enhances the function of endothelin-1-primed fibroblasts

Airway inflammation is accompanied by structural changes, termed remodeling, that lead to lung dysfunction over the long term. Although both endothelin-1 (ET-1) and cysteinyl leukotrienes (CysLTs) appear to be involved in airway remodeling in several lung diseases, how these molecules interact remains largely unknown. In this study, we examined the effects of leukotriene (LT) D(4) on the function of ET-1-primed fibroblasts. ET-1 at 10(-7) M up-regulated the expression of the CysLT receptors at both the mRNA and protein levels in human lung fibroblasts. LTD(4) enhanced matrix metalloproteinase-2 and pro-collagen production, and alpha-smooth muscle actin expression of ET-1-primed fibroblasts, but had little or no effect on unprimed fibroblasts. The CysLT1 receptor antagonist montelukast completely abrogated the effects of LTD(4). Our data suggested that LTD(4) may act as a precipitating factor during ET-1-mediated airway remodeling and that CysLT1 receptor antagonists may have a role in preventing aberrant extracellular matrix degradation.

Oral ibandronate is as active as intravenous zoledronic acid for reducing bone turnover markers in women with breast cancer and bone metastases

BACKGROUND

Phase III study comparing the effect of oral ibandronate and intravenous zoledronic acid on bone markers.

PATIENTS AND METHODS

Breast cancer patients with bone metastases received ibandronate 50 mg/day (n = 137) or zoledronic acid 4 mg every 4 weeks (n = 138) for 12 weeks. The primary end point was mean percentage change in serum levels of cross-linked C-terminal telopeptide of type I collagen (S-CTX) at week 12. Urinary CTX (U-CTX), bone alkaline phosphatase (ALP), amino-terminal procollagen propeptide of type I collagen (PINP) and osteocalcin (OC) were also measured and bone pain and safety assessed.

RESULTS

Both bisphosphonates significantly reduced S-CTX (mean ibandronate 76% +/- 29 (SD) versus mean zoledronic acid 73% +/- 47; P < 0.001 for both versus baseline) and U-CTX (ibandronate 78% +/- 50 versus zoledronic acid 86% +/- 17; P < 0.001). The difference in S-CTX between treatments was 0.6% (confidence interval -1.7% to 3.0%), which was within the prespecified noninferiority margin. Bone ALP, PINP and OC decreased by 26%-47% compared with baseline with both bisphosphonates. Compared with zoledronic acid, ibandronate patients reported fewer adverse events overall (65.0% versus 75.9%), and on days 1-3 (8.0% versus 47.5%), including less pyrexia (overall incidence 0% versus 16.8%) and bone pain (5.8% versus 12.4%).

CONCLUSIONS

Oral ibandronate was well tolerated and statistically noninferior to zoledronic acid for percentage change in the bone resorption marker, S-CTX.

Association of β-Blocker Dose with Serum Procollagen Concentrations and Cardiac Response to Spironolactone in Patients with Heart Failure

STUDY OBJECTIVE

To determine whether beta-blocker dose influences cardiac collagen turnover and the effects of spironolactone on cardiac collagen turnover in patients with heart failure.

DESIGN

Prospective clinical study.

SETTING

Two heart failure centers.

PATIENTS

Eighty-eight spironolactone-naïve patients with heart failure who were taking beta-blockers.

INTERVENTION

In a subset of 29 patients, spironolactone was started at 12.5 mg/day, with the dosage titrated to 25 mg/day if tolerated.

MEASUREMENTS AND MAIN RESULTS

Venous blood samples were collected from each patient. Serum procollagen type I and type III aminoterminal peptides (PINP and PIIINP) were determined by radioimmunoassay and compared between the 25 patients receiving low doses (< 50% of recommended target dose) and the 63 patients receiving high doses (> or = 50% of recommended target dose) of beta-blockers. Patients receiving low-dose beta-blockers had higher mean +/- SD PIIINP concentrations (6.6 +/- 3.5 vs 4.9 +/- 2.6 microg/L, p=0.03) and tended to have higher PINP concentrations (74.0 +/- 44.1 vs 57.1 +/- 28.6 microg/L, p=0.10) compared with those receiving high doses. A repeat blood sample was collected from the 29 patients who received spironolactone after 6 months of therapy. Changes in procollagen peptides also were compared in this subset between low-dose (9 patients) and high-dose (20 patients) beta-blocker groups. Low beta-blocker doses were associated with greater reductions in concentrations of PINP (median [intraquartile range] -14.3 microg/L [-9.8 to -19.3 microg/L] vs -2.5 microg/L [5.9 to -9.8 microg/L], p=0.02) and PIIINP (-1.4 microg/L [-0.9 to -2.4 microg/L] vs 0.1 microg/L [0.9 to -1.3 microg/L], p=0.045) with spironolactone therapy than high beta-blocker doses. In addition, 100% of the patients in this subset taking low-dose beta-blockers versus only 35% taking higher doses had reductions in both markers of cardiac fibrosis.

CONCLUSION

Spironolactone may benefit patients with heart failure who cannot tolerate upward titration of beta-blocker dosages, at least in terms of its effects on cardiac remodeling.

Disassociation of bone resorption and formation by GLP-2: a 14-day study in healthy postmenopausal women

We have previously shown that a single subcutaneous injection of glucagon-like peptide-2 (GLP-2) at 10 p.m. in postmenopausal women results in a dose-dependent decrease in the nocturnal serum and urine concentrations of fragments derived from the degradation of the C-terminal telopeptide region of collagen type I (s-CTX and u-CTX) and u-DPD, markers of bone resorption. In contrast, bone formation, as assessed by serum osteocalcin and procollagen type I N-terminal propeptide (PINP), appeared to be unaffected by treatment with exogenous GLP-2. These effects were further investigated in a 14-day study. The aim was to demonstrate that a parenteral formulation of GLP-2 is safe and well tolerated after repeated dosing in healthy postmenopausal women for 14 days. It was further investigated whether the effects on bone turnover markers were sustained throughout the study period. The study was a double-blind placebo-controlled trial with 60 postmenopausal women and 2 different doses of GLP-2 (1.6 mg and 3.2 mg GLP-2) against a saline control. The data for bone resorption revealed a similar reduction on Day 1 and Day 14, both based on time course and AUC. There were no signs of tachyphylaxis and no serious adverse reaction. Both GLP-2 doses resulted in similar and significant (p<0.001) reduction in bone resorption indicating that the maximum efficacious dose has been approached. Osteocalcin and PINP levels were unaffected at Day 1 and Day 14, suggesting a disassociation between bone resorption and bone formation during GLP-2 treatment.

Local simvastatin effects on mandibular bone growth and inflammation

BACKGROUND

Simvastatin has been shown to increase bone growth when applied topically to murine bone; however, it causes considerable soft tissue inflammation at high doses (2.2 mg), making future clinical use problematic. This study evaluated the effect of lower simvastatin doses and cyclooxygenase (COX) synthase inhibitors on tissue inflammation and bone growth in rats and gene expression in mice.

METHODS

Adult female rats were untreated or treated with a single dose of 0.1, 0.5, 1.0, 1.5, or 2.2 mg simvastatin in methylcellulose gel in a polylactic acid membrane (SIM) on the lateral aspect of the mandible. The contralateral mandible side was implanted with methylcellulose gel/polylactic acid membrane alone (GEL), and five rats in each dose pairing were evaluated histomorphometrically after 3, 7, and 24 days. Subsequent rats were similarly treated with 0.5 mg simvastatin (optimal dose) and daily intraperitoneal injections of COX-2 inhibitor (NS-398; 1 mg/kg x 7 days; N = 16), general COX inhibitor (indomethacin; 1 mg/kg x 7 days; N = 16), or no inhibitor (N = 10) and evaluated histomorphometrically after 7 or 24 days by analysis of variance (ANOVA). Gene arrays were also used to evaluate osteogenic gene expression from 0.5 mg simvastatin in murine calvaria (N = 12).

RESULTS

There was a 45% increase in bone area with 0.5 mg simvastatin versus gel control (P <0.001; similar to the 2.2-mg dose), and clinical swelling was reduced compared to the high simvastatin dose (P <0.05). The 0.1-mg simvastatin dose failed to stimulate significant bone growth. NS-398 and indomethacin reduced inflammation and bone growth. Simvastatin significantly upregulated procollagen, fibronectin, and matrix metalloproteinase-13 genes.

CONCLUSION

Reducing the simvastatin dose from 2.2 to 0.5 mg reduced inflammation to a more clinically acceptable level without sacrificing bone-growth potential, but COX-associated inflammation appears to be necessary for in vivo bone growth.

Effect of inhaled steroids on increased collagen synthesis in asthma

BACKGROUND

We previously reported that sputum levels of procollagen type I C-terminal peptide (PICP), a marker of ongoing collagen type I deposition, are increased in proportion to airway inflammation in asthma patients.

OBJECTIVES

In this study, we examined the effect of inhaled corticosteroids on increased collagen synthesis in step 2-4 asthmatics.

METHODS

We compared the sputum PICP concentrations of 25 steroid-naive asthmatics, 25 normal volunteers, and 10 subjects with chronic obstructive pulmonary disease. Asthma subjects were also instructed to start fluticasone propionate treatment, and the percentage of forced expiratory volume in 1 s, sputum eosinophil counts, sputum PICP concentrations, and sputum transforming growth factor-beta-positive cell counts before treatment were compared with those 1 month after treatment.

RESULTS

Sputum PICP concentrations were detected in the following order: asthma group >or= chronic obstructive pulmonary disease group > control group. Asthma patients showing high sputum PICP belonged to step 4, although there was no correlation between sputum PICP and asthma severity. Treatment with fluticasone propionate not only significantly improved the mean percentage of forced expiratory volume in 1 s (from 66.7 to 87.2%), but also decreased the mean sputum eosinophil counts (from 13.4 to 5.8%), the mean sputum PICP concentrations (from 30.8 to 10.2 ng/ml), and the mean sputum tumor growth factor-beta-positive cells (from 11.3 to 2.8%). Nevertheless, a significant difference in sputum PICP concentrations was still observed between the control group and the steroid-treated asthma group.

CONCLUSIONS

The present results suggest that inhaled corticosteroid treatment might reduce sputum indexes of collagen metabolism and eosinophilic inflammation in asthma patients.

Monitoring of Risedronate by biochemical bone markers in clinical practice

The study of trend of Risedronate 10 mg/day in menopausal women with a high level of resorptive bone marker (Betacrosslaps, CTx) by the following bone markers:Bone alkaline phosphatase (formation marker) total alkaline phosphatase (TAlP), NMID osteocalcin, undercarboxylated osteocalcin (UcOC) and procollagen type 1 carboxyl propeptides (PICP). Risedronate does not suppress bone resorption deeply that enhances the bone recovers quickly after withdrawal. The level of undercarboxylated osteocalcin was increased after one year of treatment; it may be a sign of vitamin K2 deficiency. The bone alkaline phosphatase was decreased at the end of 12 months and Procollagen type 1 carboxyl propeptides (PICP) of twelfth month changed significantly compared to the sixth months of treatment (p=0.001) The once week 70 mg/week group also changed of CTx the same as daily dose group.

The mechanism of action of topical retinoids

UV irradiation of human skin sets in motion a complex sequence of events that causes damage to the dermal matrix. When topical tretinoin is applied to human skin, any collagen deficiency existing in photoaged skin is remedied at least partially, and the skin is primed to prevent further matrix degradation induced by solar UV. Retinoids, therefore, have become essential in the treatment and prevention of photoaging. This article describes the mechanism of action of retinoids, including how they are mediated through retinoic acid receptors (RARs) and retinoid X receptors (RXRs), how they block inflammation mediators, and how production of procollagen is increased to augment the formation of types I and III collagen. Three naturally occurring retinoids are reviewed.

CXCL11 Attenuates Bleomycin-induced Pulmonary Fibrosis via Inhibition of Vascular Remodeling

Aberrant vascular remodeling is a central hallmark for the development and progression of idiopathic pulmonary fibrosis. The mechanisms underlying the pathophysiologic alterations, however, are poorly understood. A recent phase II trial of interferon gamma-1b has demonstrated a trend toward a decrease in profibrotic and proangiogenic biologic markers, and upregulation of lung CXCL11 mRNA and bronchoalveolar lavage fluid and plasma protein levels of CXCL11. We hypothesized that net aberrant vascular remodeling seen during the pathogenesis of fibroplasia and deposition of extracellular matrix during bleomycin-induced pulmonary fibrosis can be attenuated by treatment with the angiostatic ELR(-) CXC chemokine, CXCL11. In a preclinical model, systemic administration of CXCL11 reduced pulmonary collagen deposition, procollagen gene expression, and histopathologic fibroplasia and extracellular matrix deposition in the lung of bleomycin-treated mice. CXCL11 treatment significantly reduced bleomycin-induced pulmonary fibrosis without altering specific lung leukocyte populations. CXCR3 is not expressed on fibroblasts and CXCL11 had no direct functional effect on pulmonary fibroblasts. The angiogenic activity in the lung was significantly decreased, however, and CXCL11 treatment reduced the total number of endothelial cells in the lung following bleomycin exposure. The results suggest that CXCL11 inhibits pulmonary fibrosis by altering aberrant vascular remodeling.

A thyroid hormone analogue, triiodothyroacetic acid, corrects corticosteroid-downregulated collagen synthesis

The aim of this study was to compare the change in collagen synthesis between topical treatments with two doses of triiodothyroacetic acid (TRIAC), a thyroid hormone analogue, and placebo, after pretreatment with topical betamethasone 17-valerate (BM). Eighteen healthy volunteers were pretreated with BM on abdominal skin for 3 days, and were then treated for 14 days with a cream containing TRIAC (0.03% or 0.1%) or a placebo cream. Collagen production was assessed by quantifying the amino terminal propeptides of human type I and type III procollagen (PINP and PIIINP) in fluids from suction-induced blisters on the treated skin. Three days of treatment with BM led to an average reduction of PINP of 70% and of PIIINP of 50%. Seven days after treatment, the median increase in PINP was 230% (p = 0.03) in the Triac 0.03% group, 148% (p = 0.2) in the TRIAC 0.1% and 5% in the placebo group. The median increase in PINP in the skin area from the start of treatment to the end of treatment was 521% (p = 0.06) in the TRIAC 0.03% group, 339% (p = 0.2) in the TRIAC 0.1% group, and 55% in the placebo group (the p values are related to baseline). Seven days after treatment, the median increase in PIIINP was 24% (p = 0.6) in the Triac 0.03% group, 23% (p = 0.6) in the TRIAC 0.1% group, and -12% in the placebo group. The median increase in PIIINP in the skin area from the start of treatment to the end of treatment was 137% (p = 0.7) in the TRIAC 0.03% group, 230% (p = 0.9) in the TRIAC 0.1% group and 58% in the placebo group (the p values are related to baseline). Histologic examinations of sections from punch biopsies taken at the end of the treatment showed more thickened collagen fibers and increased density of PINP-producing dermal fibroblasts in the TRIAC groups compared to the placebo group. The result suggests a potential role for TRIAC-containing cream concomitant with anti-inflammatory topical treatment with potent glucocorticoids to prevent their suppressive activity on dermal collagen production.

Prediction of the change in bone mineral density induced by gonadotropin-releasing hormone agonist treatment for endometriosis

OBJECTIVE

To observe the long-term changes in bone metabolism induced by GnRH agonist (GnRHa) treatment and to determine the factor that affected the change in bone mineral density (BMD).

DESIGN

Prospective observational study.

SETTING

Department of obstetrics and gynecology in university and general hospitals.

PATIENT(S)

Fifty women with endometriosis treated with GnRHa between 1994 and 1996.

INTERVENTION(S)

Leuprolide acetate administered for 24 weeks. Bone mineral density measurement by dual energy x-ray absorptiometry and collection of blood and urine samples were conducted until 12 months of posttreatment.

MAIN OUTCOME MEASURE(S)

Spinal BMD and bone turnover markers.

RESULT(S)

Mean BMD percent changes from pretreatment were -4.9% and -3.4% at 6 months of treatment and at 12 months of posttreatment, respectively. When the patients were divided by the median pretreatment deoxypyridinoline (DP) level, recovery of BMD after GnRHa discontinuation was slower in the Low-DP group than in the High-DP group. A significant positive correlation was found between the pretreatment DP level and the percent change in BMD at 12 months of posttreatment. No significant relation between BMD and the other bone turnover markers was noted.

CONCLUSION(S)

Bone mineral density changes were diverse among patients who were administered GnRHa. The pretreatment DP level may be the predictive factor for GnRHa-induced BMD change.

Reduction in PINP, a marker of bone metabolism, with raloxifene treatment and its relationship with vertebral fracture risk

In the Multiple Outcomes of Raloxifene Evaluation (MORE) trial, 7705 postmenopausal women with osteoporosis, defined by low bone mineral density and/or prevalent vertebral fractures (VF), were randomized to placebo or raloxifene (60 or 120 mg/day). All women received daily calcium (500 mg) and vitamin D (400-600 IU) supplements. Our previous analyses found that changes in BMD and biochemical markers of bone turnover are poorly predictive of the reduction in VF risk observed with raloxifene. This present study evaluated the effects of raloxifene on type I procollagen N-terminal propeptide (PINP), a new marker of bone turnover. Logistic regression analysis models evaluated the relationships between the changes at 1 year in PINP, serum osteocalcin (OC), bone-specific alkaline phosphatase (BSAP), and urinary excretion of type I collagen C-telopeptide fragments normalized to creatinine (CTx/Cr), and the risk of new VF at 3 years for placebo and pooled raloxifene. A subset of 967 women (mean age = 68 years) from the MORE cohort had PINP, OC, BSAP, and CTx evaluated at baseline. Both doses of raloxifene significantly decreased (P < 0.001) all biochemical markers of bone turnover from baseline. Compared to baseline, PINP levels were decreased by medians of 11.0% and 40.8% in the placebo and pooled raloxifene groups, respectively. In addition, the placebo and pooled raloxifene groups decreased serum OC by 8.5% and 31.8%, BSAP by 15.8% and 34.6%, and urinary CTx/Cr excretion by 5.6% and 46.5%, respectively, from baseline. In the pooled raloxifene group, the logistic regression relationship between 3-year VF risk and 1-year percentage change for each biochemical marker was statistically significant with PINP (slope estimate = 0.0085, P = 0.009), OC (slope estimate = 0.0068, P = 0.035), and BSAP (slope estimate = 0.0056, P = 0.039), but not with CTx/Cr (slope estimate = 0.0027, P = 0.192). Furthermore, the percent decrease in PINP at 1 year could account for 28% of the total reduction in vertebral fracture risk. In conclusion, a 1-year decrease in PINP, BSAP, or OC, but not CTx/Cr, may be predictive of the 3-year VF risk reduction with raloxifene therapy in this subset of postmenopausal women with osteoporosis.

Inhibition of autophagy with 3-methyladenine results in impaired turnover of lysosomes and accumulation of lipofuscin-like material

Autophagy (which includes macro-, micro-, and chaperone-mediated autophagy) is an important biological mechanism for degradation of damaged/obsolete macromolecules and organelles. Ageing non-dividing cells, however, progressively accumulate oxidised proteins, defective organelles and intralysosomal lipofuscin inclusions, suggesting inherent insufficiency of autophagy. To learn more about the role of macroautophagy in the turnover of organelles and lipofuscin formation, we inhibited autophagic sequestration with 3-methyladenine (3 MA) in growth-arrested human fibroblasts, a classical model of cellular ageing. Such treatment resulted in a dramatic accumulation of altered lysosomes, displaying lipofuscin-like autofluorescence, as well as in a moderate increase of mitochondria with lowered membrane potential. The size of the late endosomal compartment appeared not to be significantly altered following 3 MA exposure. The accumulation of lipofuscin-like material was enhanced when 3 MA administration was combined with hyperoxia. The findings suggest that macroautophagy is essential for normal turnover of lysosomes. This notion is supported by reports in the literature of lysosomal membrane proteins inside lysosomes and/or late endosomes, as well as lysosomes with active hydrolases within autophagosomes following vinblastine-induced block of fusion between lysosomes and autophagosomes. The data also suggest that specific components of lysosomes, such as membranes and proteins, may be direct sources of lipofuscin.

[An experimental study on airway inflammation and remodeling in a rat model of chronic bronchitis and emphysema]

OBJECTIVE

To study the pathological features of airway inflammation and remodeling in rats with chronic bronchitis (CB) and emphysema and to evaluate the protective and therapeutic effects of erythromycin (EM).

METHODS

Forty-three Wistar rats were assigned to eight groups: normal control group (A group, n = 5), normal saline solution group (P group, n = 5), CB group (L group, n = 6), CB and emphysema group (S group, n = 6), low-dose EM-treatment group (E(1) group, n = 5), high-dose EM-treatment group (E(2) group, n = 6), low-dose EM-prevention group (E(10) group, n = 5) and high-dose EM-prevention group (E(20) group, n = 5). The rat model of CB and emphysema was established by intratracheal instillation of lipopolysaccharide (LPS) and daily exposure to cigarette smog. After four weeks, total and differential cell counts in bronchoalveolar lavage fluid (BALF) were observed, and the pathomorphological changes in the lung were analyzed. The thickness of the smooth muscles and collagen in the bronchial wall were measured. Expression and localization of transforming growth factor beta(1) (TGF-beta(1)) were observed in the bronchi and lung tissues by immunohistochemistry. The levels of hyaluronic acid (HA) and procollagen type III (PCIII) in the serum and BALF were determined by the radioimmunoassay (RIA).

RESULTS

(1) Compared with A group [(0.9 +/- 0.7) x 10(5)/ml], absolute neutrophil count in BALF from S group [(17.1 +/- 10.8) x 10(5)/ml] were significantly higher (P < 0.01). (2) Both the pathologic scores obtained from the S group (329 +/- 114) and P group (67 +/- 25), and the thickness of smooth muscles and collagen from S group [(9.6 +/- 2.6)%] and A group [(6.1 +/- 1.8)%] were statistically different (P < 0.01, P < 0.05, respectively). Expression of TGF-beta(1) in the lung of S group was significantly higher than that in A group. (3) The levels of HA [(152.5 +/- 36.3) micro g/ml] and PCIII [(40 +/- 8) micro g/ml] in serum and the levels of HA [(94 +/- 35) micro g/ml] and PCIII [(39 +/- 7) micro g/ml] in BALF in S group were higher than those in A group (P < 0.01). (4) After treatment with 100 mg/kg EM, absolute neutrophil count in BALF, the pathologic scores, the thickness of smooth muscles and collagen in the bronchi, the levels of PCIII and HA in serum and the levels of PCIII and HA in BALF were reduced to (2.1 +/- 1.4) x 10(5)/ml, 187 +/- 61, (6.0 +/- 2.3)%, (9.69 +/- 5.61) micro g/ml, (63.0 +/- 11.6) micro g/ml, (16 +/- 6) micro g/ml, (52 +/- 12) micro g/ml, respectively. Statistical analysis revealed that there were significant differences as compared to those of group S (P < 0.05).

CONCLUSIONS

Many inflammatory cells especially neutrophils and alveolar macrophages might play an important role in the airway inflammation of CB and emphysema. Thickening of smooth muscles and collagen in the bronchi and the excessive depositions of extracellular matrix (ECM) constitute the fundamental pathological characteristic of airway remodeling in CB and emphysema. EM may prevent airway inflammation and remodeling to some degree.

Interleukin-6 and tumor necrosis factor alpha in relation to myocardial infarct size and collagen formation

BACKGROUND

Interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) levels increase after acute myocardial infarction (AMI) in humans. Experimental data suggest that these cytokines regulate the initiation of scar formation after AMI. We investigated the interrelationships of IL-6 and TNF-alpha, tissue injury, infarct size, cardiac function, and collagen formation in humans.

METHODS

Serum and plasma samples were taken on 93 patients receiving thrombolytic treatment for their first AMI. Collagen formation was evaluated by measuring concentrations of serum aminoterminal propeptide of type III procollagen (PIIINP).

RESULTS

IL-6 levels increased by 44% (P<.001) and peaked at 24 hours. Peak IL-6 levels correlated positively with area under the curve of creatine kinase MB mass (r=.31, P<.01), peak troponin T level (r=.34, P<.005), and PIIINP measured at discharge (r=.46, P<.001). There were no changes in TNF-alpha levels, and patients with left ventricular dysfunction (EF<40%) had similar TNF-alpha levels as those with preserved left ventricular function.

CONCLUSIONS

IL-6 may regulate collagen formation and thus remodeling of the left ventricle after AMI. In addition, TNF-alpha measurement is useless in the assessment of infarct size or left ventricular function during the immediate post-infarction period.

Effect of antiviral therapy on markers of fibrogenesis in patients with chronic hepatitis C

BACKGROUND

The possible markers of liver fibrosis (plasma YKL-40, PIIINP, MMP-2 and TIMP-1) were measured at the start (t0) and end of treatment (t12) with alpha-interferon and ribavirin and repeated at 6-months follow-up (t18) in 51 patients with chronic hepatitis C.

METHODS

We evaluated 1) whether treatment response is reflected by a decrease in these markers during antiviral therapy; 2) whether these markers reflect the activity of the disease; and 3) whether these markers could be used as predictors of the treatment response.

RESULTS

Baseline plasma YKL-40, MMP-2, PIIINP and TIMP-1 were significantly increased in patients compared to normal controls. In responders (n = 30), plasma YKL-40 (P < 0.05), MMP-2 (P < 0.05) and TIMP-1 (P < 0.001) decreased significantly at t18, and no changes were observed at t12. Plasma PIIINP was unchanged in responders. In non-responders (n = 19), plasma MMP-2 (P < 0.01) and TIMP-1 (P < 0.01) decreased significantly at t18, whereas plasma YKL-40 and PIIINP were unchanged. The markers were significantly correlated at baseline (P < 0.001). Plasma PIIINP at baseline could predict treatment response (P = 0.01).

CONCLUSIONS

Response to antiviral treatment is associated with a decrease in the fibrogenetic markers, but the markers do not reflect the biochemical disease activity during treatment. Baseline plasma PIIINP was the only marker predicting treatment response.

Effect of estrogen replacement on insulin sensitivity, serum lipid and bone resorption marker in hypogonadal males

Recent reports of osteoporosis in congenital estrogen deficiency in humans from estrogen resistance or aromatase deficiency have called attention to the importance of estrogen in males. It is the purpose of the present study to evaluate the effects of low- dose estrogen on glucose, lipid and bone metabolism in males with hypogonadism. Nine Thai males with primary or secondary hypogonadism were included in the study. Testosterone was discontinued at least 8 weeks before the study. The subjects received 0.3 mg of conjugated equine estrogen (CEE) daily for 4 weeks. Serum C-terminal telopeptide of type 1 collagen (CTX), total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), triglyceride (TG) and parameters related to insulin sensitivity were measured at baseline and 4 weeks after treatment. Insulin sensitivity was assessed by frequent intravenous glucose tolerance test. The mean age of subjects was 35.77 years (22-70 years). Insulin sensitivity index (SI) did not change significantly after the administration of CEE (P=0.09). Likewise, no change in acute insulin response (AIR(glucose)) was detected. However, glucose effectiveness (SG) significantly decreased after CEE (P<0.05). No significant change in serum TC, LDL-C, HDL-C or TG was detected. In regard to bone turnover, serum CTX significantly decreased after CEE administration (P<0.05). We concluded that low-dose estrogen administration in hypogonadal males for 4 weeks causes a decrease in bone turnover and an increase in glucose effectiveness. No effect on serum lipid concentrations or insulin sensitivity and secretion was detected.

Long-term changes in collagen formation expressed by serum carboxyterminal propeptide of type-I procollagen and relation to left ventricular function after acute myocardial infarction

The purpose of this study was to investigate the long-term sequential changes in serum levels of the carboxyterminal propeptide of type-I procollagen (s-PICP), which is a marker of type-I collagen synthesis, and to assess its clinical value in relation to left ventricular (LV) function and prognosis following acute myocardial infarction (AMI). Forty-eight consecutive patients with their first AMI and 15 control subjects were studied. Patients with AMI were stratified according to the changes in s-PICP levels between days 1 and 90 (DeltaPICP) and divided into group I with < or =16.0 microg/l or group II with >16.0 microg/l. Patients in group II were characterized by LV dilatation, no improvement in ejection fraction and development of impaired diastolic filling from day 1 to 360, findings which were in contrast to group I. Cox regression analysis identified changes in s-PICP of >16.0 microg/l as an independent predictor of cardiac death or heart failure during follow-up. In conclusion, DeltaPICP relates to long-term changes in LV function and size, and provides prognostic information following AMI.

Anti-oxidant ebselen causes the resolution of experimentally induced hepatic fibrosis in rats

BACKGROUND

Hepatic fibrosis occurs because of injury to the liver parenchyma and biliary system. We have investigated the effect of an organic selenium anti-oxidant, ebselen, in the resolution of experimentally induced hepatic fibrosis, and evaluated its effect on various paradigms involved in hepatic fibrosis.

METHODS

Following pretreatment with phenobarbitone, liver fibrosis was induced in male Fischer 344 rats by using carbon tetrachloride treatment for 10 weeks. Carbon tetrachloride-treated rats were randomly assigned into two groups: (i) no ebselen; and (ii) ebselen administered for 3 weeks following a 10-week carbon tetrachloride treatment period. Normal controls were: (i) neither carbon tetrachloride nor ebselen treated; or (ii) ebselen treated for 13 weeks. Liver sections were stained with hematoxylin and eosin, Masson trichrome and stained for reticulin by using silver impregnation. Reverse transcription-polymerase chain reaction was used to analyze the steady-state levels of gene(s) involved in: (i) hepatic fibrosis, namely, transforming growth factor-beta1, procollagen I and III, tissue inhibitor of metalloproteinase-1 and matrix metalloproteinase-13; (ii) oxidative stress, namely, cytochrome P4502E1; and (iii) preneoplastic liver foci, namely, the placental form of glutathione-S-transferase.

RESULTS

Histological staining showed that ebselen resolves carbon tetrachloride-induced hepatic fibrosis. Treatment with ebselen reduced steady-state levels of transforming growth factor-beta1, procollagen I and III, tissue inhibitor of metalloproteinase-1, cytochrome P4502E1 and placental form glutathione-S-transferase transcripts, and increased transcripts of matrix metalloproteinase-13.

CONCLUSION

These findings provide evidence that ebselen significantly causes the resolution of carbon tetrachloride-induced hepatic fibrosis in rats.

The role of retinoids in the prevention and repair of aged and photoaged skin

Retinoids, either naturally occurring or synthetic, are defined by their ability to bind nuclear retinoid receptors of the steroid/thyroid superfamily. Their protean but key function in physiology is control of cellular proliferation and differentiation. Topical retinoids, namely tretinoin, have been proven to prevent and repair clinical features of photoageing; these processes are facilitated by an ability to prevent loss of collagen from, and stimulate new collagen formation in, the papillary dermis of sun-exposed skin. Emerging evidence indicates that intrinsic, chronological ageing of the skin shares several mechanistic features with photoageing. Indeed aged skin is characterized by retinoid sensitivity and is probably reparable by application of topical retinoids.

Influence of aldosterone on collagen synthesis and proliferation of rat cardiac fibroblasts

1. Previous in vivo studies in men and experimental animal models have shown that hyperaldosteronemia is correlated with cardiac fibrosis due to increased total collagen synthesis. As yet, it is unclear whether aldosterone has direct pro-fibrogenic effect on cardiac fibroblasts, the fibrogenic effector cell in the myocardium, and if so which procollagens specifically are synthesized at higher rates. 2. The present study aims at establishing whether de novo collagen synthesis by cardiac fibroblasts is enhanced following exposure for 2x24 h to pharmacological (10(-7) - 10(-8) M), near-physiological (10(-9) M) or physiological (10(-10) - 10(-11) M) aldosterone concentrations. During the last 24 h, cells were metabolically labelled with [35S]-methionine/[35S]-cysteine. Labelled procollagens were immunoprecipitated quantitatively using antibodies against specific procollagens. Contrary to expectations, 10(-7) M aldosterone inhibited significantly de novo synthesis of procollagens type I and IV (-35% and -42%, respectively). For procollagen type III, only a tendency towards inhibition was observed. At lower concentrations of aldosterone (10(-8) - 10(-10) M), synthesis of procollagens type I, III or IV was unaffected. 3. Cellular DNA synthesis under influence of aldosterone was evaluated by measuring BrdU incorporation. Cells were treated with aldosterone, while BrdU was added during the last 16 h of treatment. Aldosterone had no demonstrable effect on cellular proliferation. 4. Reverse transcription-polymerase chain reaction (RT - PCR) clearly demonstrated the presence of mineralocorticoid receptor mRNA in cardiac fibroblasts. 5. In spite of the expression of the mineralocorticoid receptor by cultured cardiac fibroblasts, the pro-fibrogenic effect of aldosterone as observed in vivo, is not likely to be due to a direct effect of this hormone in cardiac fibroblasts.

The effects of high levels of glucose and insulin on type I collagen synthesis in mature human odontoblasts and pulp tissue in vitro

High levels of dietary sucrose affect the metabolism of the pulp-dentin complex and enhance the caries process in dentin. The high-sucrose diet reduces dentin formation in young rats (Tjäderhane et al., 1994; Hietala and Larmas, 1995; Tjäderhane, 1996) and in pups of rat dams fed high-sucrose diet during lactation (Pekkala et al., 2000a). However, the mechanisms behind the effects are unknown. A direct effect of elevated blood glucose or an indirect effect via insulin has been suggested. We investigated the effects of high glucose and insulin on type I collagen synthesis in human odontoblasts and pulp tissue in vitro, using an organ culture method for functional post-mitotic odontoblasts. Odontoblasts and pulp tissue were cultured separately for 10 days in DMEM with 15% FBS containing additional glucose (G) (4.45 g/L) or insulin (I) (0.6 microgram/mL) or both together (GI). We evaluated type I collagen synthesis with RIA, measuring the level of N-terminal propeptide of type I collagen (PINP) secreted into the culture media. PINP secretion decreased in odontoblasts and pulp tissue in G and GI groups when compared with the control and insulin samples (p = 0.001 in both groups in the pulp samples). Insulin alone did not affect PINP secretion distinctly. The results indicate that high levels of glucose, but not insulin, directly down-regulate the type I collagen synthesis in young, differentiated human odontoblasts and pulp tissue. Insulin does not affect the inhibitory effect of high sucrose. These in vitro findings indicate that the high-sucrose diet may alter odontoblast function independently of insulin.

Human odontoblast culture method: the expression of collagen and matrix metalloproteinases (MMPs)

Studies on mature human odontoblasts have suffered for the lack of in vitro models. We recently introduced a human odontoblast and pulp tissue organ culture method, in which the odontoblasts are cultured in the pulp chamber after removal of the pulp tissue, and the pulp tissue can be cultured separately (Tjäderhane et al., 1998a). With this method, we have studied the effects of growth factors on the expression of collagen and extracellular matrix (ECM)-degrading enzymes, matrix metalloproteinases (MMPs), in mature human odontoblasts. TGF-beta 1 was selected because of its ability to regulate the response of the dentin-pulp complex to external irritation. The effect of TGF-beta 1 (10 ng/mL) on pro alpha 1(I) collagen mRNA was analyzed by quantitative PCR, and type I procollagen propeptide (PINP) was analyzed from conditioned culture media with RIA. Odontoblast media were also assayed for respective type III procollagen propeptide (PIIINP). TGF-beta had a negligible effect on collagen mRNA expression or protein synthesis, indicating that TGF-beta alone does not markedly induce dentin matrix formation per se in the human dentin-pulp complex (Palosaari et al., 2001). However, TGF-beta 1 seems to regulate MMP expression in mature human odontoblasts differentially. A strong down-regulation of MMP-8 (Palosaari et al., 2000), a modest down-regulation of MMP-20 (Tjäderhane et al., 2000), and considerable up-regulation of MMP-9, with no apparent effect on MMP-2 expression (Tjäderhane et al., 1998b), indicate that growth factors may affect the matrix synthesis by controlling the expression and activity of MMPs instead of collagen synthesis. The altered expression of MMPs may result in altered ECM formation, which in turn may contribute to the formation of atubular reparative dentin.

Effect of short-term antenatal dexamethasone administration on type I collagen synthesis and degradation in preterm infants at birth

To assess the effects of antenatal corticoid administration on foetal collagen metabolism, cord serum concentrations of the aminoterminal propeptide and carboxyterminal telopeptide of type I procollagen (PINP and ICTP), which reflect rates of type I collagen synthesis and degradation, respectively, were measured in 67 consecutive preterm infants with gestational ages ranging from 24 to 32 wk. The samples were divided into three groups, depending on the administration and timing of antenatal corticosteroid treatment for enhancement of foetal lung maturity: cases in which the mothers had received a full 2-dose administration of dexamethasone on consecutive days 1 to 6 d before delivery (n = 23; Complete-Dexa), those who had received only a single dose of dexamethasone less than 24 h before delivery (n = 17; Partial-Dexa) and those who had not received any antenatal steroids (n = 27; No-Dexa). Infants in the Complete-Dexa group had significantly lower median PINP levels than those in the No-Dexa group (3,326 vs 4,028 microg/l; p = 0.036); the median PINP level in the Partial-Dexa group (3,999 microg/l) was close to that of the No-Dexa group. No significant differences in ICTP concentrations were seen between the groups.

CONCLUSION

A significant suppression of foetal collagen synthesis but not degradation was found to be associated with antenatal dexamethasone administration. This should be taken into consideration, e.g. when assessing whether to administer repeated or single courses of corticosteroids antenatally in high-risk pregnancies.

Effects of dexamethasone on proliferation, chemotaxis, collagen I, and fibronectin-metabolism of human fetal lung fibroblasts

Premature infants at risk for bronchopulmonary dysplasia (BPD) are often treated with dexamethasone (Dex), which has been shown to suppress inflammatory processes in the lung. To elucidate a possible direct influence on the fibroproliferative component of the disease, we studied the effects of Dex in therapeutic and supratherapeutic dosages (5-50 nmol/L) on proliferation, chemotaxis, procollagen I, and fibronectin metabolism of human fetal lung fibroblasts in vitro. Proliferation was inhibited by Dex in a dose-dependent manner. Chemotactic activity in response to conditioned medium of human fetal fibroblasts also showed a dose-dependent inhibition after pretreatment with Dex. The amount of procollagen I C-terminal propeptide and fibronectin per cell in the cell culture supernatant was increased in the presence of Dex. Our results show that Dex does not uniformly suppress the fibroproliferative activity of human fetal lung fibroblasts, which may explain in part the unsatisfactory long-term effects of Dex treatment in BPD.

Trichostatin A, lead compound for development of antifibrogenic drugs

Eukaryotic gene expression has mainly been studied in the context of trans-acting transcription factors and their interaction with regulatory cis-elements. Evidence is accumulating, that the higher order structure of chromatin also plays an essential role in eukaryotic gene expression. Hepatic stellate cells are the major cellular source of extracellular matrix synthesis in chronic liver diseases leading to fibrosis. We explored the antifibrogenic effect of the histone deacetylase inhibitor trichostatin A (TSA) on hepatic stellate cells in vitro. Primary hepatic stellate cells as well as activated, subcultured stellate cells were exposed to 10(-7) M-10(-9) M TSA. Collagens type I and III, and smooth muscle alpha-actin (alpha-SMA), a marker for transdifferentiation, were investigated at the protein and mRNA level by performing Northern hybridisation and quantitative immunoprecipitation. The antiproliferative effect was examined by 3H-thymidine incorporation and cell counting. Hyperacetylation of histone H4 was demonstrated by acid urea Triton-X-100 (AUT) polyacrylamide gel electrophoresis. TSA at 10(-7) M retarded the morphological changes characteristics for activation of primary stellate cells. Synthesis of collagens type I and III, and alpha-SMA was strongly inhibited at both protein and mRNA level. The proliferation rate of primary hepatic stellate cells was strongly suppressed by 10(-7) M TSA. Hyperacetylation of histone H4 showed to be maximal at 10(-7) M TSA. Primary hepatic stellate cells were more affected by TSA than subcultured stellate cells.

Pravastatin therapy increases procollagen I N-terminal propeptide (PINP), a marker of bone formation in post-menopausal women

BACKGROUND

The aim of our study was to evaluate whether pravastatin treatment affected biochemical markers of bone turnover.

METHODS

Thirty-six hypercholesterolemic post-menopausal women, not on hormonal replacement therapy, were selected from a population study evaluating factors affecting cholesterol response to pravastatin. After a 6-week period on a 30% fat diet, participants received treatment with 20 mg/day of pravastatin during a 16-week follow-up period. Pre- and post-treatment samples were analyzed for procollagen I aminoterminal peptide (PINP) and bone alkaline phosphatase (bAP) as markers of bone formation, carboxyterminal telopeptide of collagen I (CTX) as a marker of bone resorption, and procollagen III aminoterminal propeptide (PIIINP) as a marker of fibrogenesis.

RESULTS

Total cholesterol decreased from 7.26+/-0.83 to 6.1+/-0.77 mmol/l with pravastatin treatment. PINP levels significantly increased (from 33.6+/-13 to 37.4+/-16, p=0.03) without changes in bAP or CTX. Individual changes in PINP correlated with individual reduction in cholesterol levels (r=0.337, p=0.04). There was no significant change in PIIINP concentration.

CONCLUSIONS

Pravastatin treatment increased PINP levels, a marker of bone formation, in hypercholesterolemic, post-menopausal women, without affecting bone resorption. PIIINP concentration, a marker of liver fibrogenesis, was not affected by the treatment.

Down-regulation of procollagen alpha1[I]] messenger RNA by titanium particles correlates with nuclear factor kappaB (NF-kappaB) activation and increased rel A and NF-kappaB1 binding to the collagen promoter

Previously, we showed that exposure of human osteoblasts to titanium particles stimulates protein tyrosine phosphorylation (PTP), activates the transcription factor nuclear factor kappaB (NF-kappaB), and causes an approximately 50% decrease in the steady-state messenger RNA (mRNA) level of procollagen alpha1[I]. In this study, we identify three NF-kappaB binding sites within the human procollagen alpha1[I] gene promoter, show that titanium particles stimulate their binding of the NF-kappaB subunits Rel A (p65) and NF-kappaB1 (p50), and find NF-kappaB activation correlates with collagen gene suppression by titanium particles in osteoblasts. Protein tyrosine kinase (PTK) inhibitors, which significantly reduce the suppressive effect of titanium particles on collagen gene expression, inhibited NF-kappaB binding activity showing that titanium particle stimulation of PTK signals in osteoblasts are critical for both NF-kappaB activation and collagen gene expression. The antioxidant pyrrolidine dithiocarbamate (PDTC), which also inhibits the titanium particle suppression of collagen, abrogated the titanium particle activation of NF-kappaB, suggesting the involvement of redox signals in NF-kappaB-mediated collagen gene expression. The RNA polymerase II inhibitor actinomycin D (Act D) decreased procollagen alpha1[I] mRNA expression and effectively blocked the titanium-induced suppressive effect, suggesting that titanium particles activate a cascade of signals in osteoblasts, which result in a suppression of procollagen alpha1[I] mRNA. Collectively, these results show that titanium particles can activate NF-kappaB signaling in osteoblasts and suggest that NF-kappaB binding to the collagen gene promoter has a functional role in the down-regulation of procollagen alpha1[I] gene transcription.

The inhibitory effects of camptothecin, a topoisomerase I inhibitor, on collagen synthesis in fibroblasts from patients with systemic sclerosis

The main manifestation of systemic sclerosis (SSc) is the overproduction of extracellular matrix, predominantly type I collagen. This study was undertaken to evaluate the effects of noncytotoxic doses of the topoisomerase I inhibitor camptothecin (CPT) on collagen production in the activated dermal fibroblasts from patients with SSc and healthy donors. The fibroblasts were cultured in the presence or absence of CPT. Production of collagenous proteins by fibroblasts was determined in cell and matrix layers by ELISA and in conditioned media by [(3)H]proline incorporation, gel electrophoresis, and autoradiography. Expression of alpha2(I) collagen (COL1A2) mRNA was measured by northern blot, and the activity of COL1A2 promoter was determined by a chloramphenicol acetyltransferase assay. CPT (10(-7) M) decreased the deposition of type I collagen by 68%, of type III by 38%, and of type VI by 21% in SSc fibroblasts and to a lesser degree in healthy controls. Similarly, CPT (10(-8) M to 10(-6) M) significantly inhibited secretion of newly synthesized collagenous proteins into conditioned media by 50%. CPT (10(-8) M to 10(-6) M) caused a significant dose-dependent inhibition of COL1A2 mRNA levels and COL1A2 promoter activity, both by as much as 60%. The inhibitory effect of CPT on collagen production by fibroblasts from patients with SSc suggests that topoisomerase I inhibitors may be effective in limiting fibrosis in such patients.

Influence of vitamin D and retinoids on the induction of functional differentiation in vitro of canine osteosarcoma clonal cells

The efficacy of 22-oxacalcitriol (OCT), calcitriol, cholecalciferol, all-trans retinoic acid (ATRA) and 9-cis retinoic acid (9-cis RA) to differentiate in vitro four clonal cells of the canine osteosarcoma cell line POS into cells having properties of a functionally mature osteoblast bone cell were investigated. The induction of intracellular alkaline phosphatase (ALP) activity, osteocalcin (GLA-OC) and type I collagen (PIP) production after 72 h treatment were used as markers of differentiation. At a concentration of 10(-8)M, OCT and calcitriol significantly induced all markers, and ATRA only the ALP of osteoblast, chondroblast and undifferentiated clonal cells. At the same concentration, 9-cis RA and cholecalciferol induced ALP of chondroblast and osteoblast cells, respectively; ATRA, 9-cis RA and cholecalciferol induced PIP of chondroblast and undifferentiated cells. None of the drugs significantly differentiated fibroblast cells. The ability of these agents to differentiate osteosarcoma cells into cells that exhibit properties of functionally mature osteoblastic bone cells may promote normal osteogenesis and reverse the loss of control of their differentiation.

Estrogen deficiency is a potential cause for osteopenia in adult male patients with Noonan's syndrome

Osteopenia is frequently observed in patients with Turner's syndrome. By contrast, there is no report concerning bone metabolism in patients with Noonan's syndrome which comprises Turner's phenotypic characteristics without any sex chromosome abnormalities. In the present investigation, we determined bone mineral density (BMD) as well as serum and urine indices of bone turnover in two male patients with Noonan's syndrome. Both patients showed remarkably decreased BMD, measured at two sites on the lumbar spine (L2-L4) and the distal end of the radius using dual energy X-ray absorptiometry (DXA). Urinary pyridinoline (PYD) and deoxypyridinoline (DPD) concentrations were significantly elevated in both patients, and serum osteocalcin and carboxyterminal propeptide of type I procollagen (PICP) concentrations were elevated in one patient. Surprisingly, both patients had a low level of serum 17beta-estradiol compared with control males, whereas they had normal levels of serum testosterone and dihydrotestosterone. Conjugated estrogens (Premarin 0.625 mg/day) were continued to be administered to these patients, followed up for 12 months. Urinary PYD and DPD concentrations gradually decreased, followed by an increase in their BMD. This is the first report that male patients with Noonan's syndrome showed osteopenia associated with increased bone resorption. Our data indicate that hypoestrogenism plays a potentially significant role in the abnormal bone metabolism in these patients.

Interferon-alpha treatment decreases serum cross-linked C-terminal telopeptide of type I collagen in haematological diseases

Interferon-alpha (IFN-alpha) is used in the treatment of many haematological diseases and it is known that IFN-alpha may affect bone turnover. The effect of IFN-alpha on bone metabolism was studied in 10 haematological patients. The mean duration of the treatment was 4 (range: 2.8-7.2) months. Besides the usual markers of bone metabolism, levels of the cross-linked C-terminal telopeptide of type I collagen (ICTP), the N-terminal propeptide of type I procollagen (PINP) and the bone-specific alkaline phosphatase were measured. The bone mineral density was measured by computed tomography. During IFN-alpha treatment, serum ICTP decreased from a mean of 5.4 (range: 1.8-12.4) to 3.6 (range: 1.4-8.8) microg/l (P = 0.017). All other variables reflecting bone metabolism remained unaltered during IFN-alpha treatment. The bone mineral density remained unchanged. It was concluded that the observed decrease in ICTP may be an indicator of a beneficial therapeutic effect of IFN-alpha on bone turnover, resulting in decreased bone resorption. However, it is possible that elevated pretreatment ICTP values reflected disease of the bone marrow.

Effect of estrogen on cellular metabolism of the human anterior cruciate ligament

Previous studies from this laboratory have established the presence of estrogen receptors in the human anterior cruciate ligament. The purpose of this study was to investigate the effects of 17 beta-estradiol on cell proliferation and procollagen levels, as an indicator of collagen synthesis, in the human anterior cruciate ligament fibroblasts. Fibroblast proliferation and procollagen synthesis in response to near log concentrations of 17 beta-estradiol (at 0.0029 ng/mL, 0.025 ng/mL, 0.25 ng/mL, 2.5 ng/mL, and 25 ng/mL) were assessed with the measurement of 3H-thymidine incorporation and Types 1 and 3 procollagen specific equilibrium radioimmunoassays. On Days 1 and 3, there was a dose dependent decrease in the proliferation of anterior cruciate ligament fibroblasts with increasing estradiol concentrations. This dose dependent effect of decreased fibroblast proliferation with increasing estradiol concentrations became less apparent at 7, 10, and 14 days. On Days 1 and 3, procollagen synthesis decreased in a dose dependent manner with increasing estradiol concentrations. On Days 7, 10, and 14, this dose dependent effect was attenuated. No significant differences in Type 3 procollagen synthesis by anterior cruciate ligament fibroblasts were observed with varying estradiol concentrations at any of the designated points. These early physiologic changes in fibroblast proliferation and Type I procollagen synthesis may provide a biologic explanation for the increased anterior cruciate ligament injury rate observed in female athletes, suggesting that it is the acute cyclic variations in the female athlete who is menstruating that predisposes her to ligamentous injury.

Intracellular retention of procollagen within the endoplasmic reticulum is mediated by prolyl 4-hydroxylase

The correct folding and assembly of proteins within the endoplasmic reticulum (ER) are prerequisites for subsequent transport from this organelle to the Golgi apparatus. The mechanisms underlying the ability of the cell to recognize and retain unassembled or malfolded proteins generally require binding to molecular chaperones within the ER. One classic example of this process occurs during the biosynthesis of procollagen. Here partially folded intermediates are retained and prevented from secretion, leading to a build up of unfolded chains within the cell. The accumulation of these partially folded intermediates occurs during vitamin C deficiency due to incomplete proline hydroxylation, as vitamin C is an essential co-factor of the enzyme prolyl 4-hydroxylase. In this report we show that this retention is tightly regulated with little or no secretion occurring under conditions preventing proline hydroxylation. We studied the molecular mechanism underlying retention by determining which proteins associate with partially folded procollagen intermediates within the ER. By using a combination of cross-linking and sucrose gradient analysis, we show that the major protein binding to procollagen during its biosynthesis is prolyl 4-hydroxylase, and no binding to other ER resident proteins including Hsp47 was detected. This binding is regulated by the folding status rather than the extent of hydroxylation of the chains demonstrating that this enzyme can recognize and retain unfolded procollagen chains and can release these chains for further transport once they have folded correctly.

Mineral dusts directly induce epithelial and interstitial fibrogenic mediators and matrix components in the airway wall

Exposure to mineral dusts is associated with the development of chronic airflow obstruction, probably mediated in part by dust-induced fibrosis of the small airways. To investigate the mechanism of fibrosis, we exposed rat tracheal explants to amosite asbestos, iron oxide, or titanium dioxide. Explants were then maintained in air organ culture, and the expression of genes encoding for various mediators and matrix components assessed by reverse transcriptase-polymerase chain reaction (RT-PCR). At 7 d, all dusts produced significant increases in platelet-derived growth factor-A (PDGF-A) and transforming growth factor-beta1 (TGF-beta1) gene expression compared with control; asbestos and titanium dioxide produced increases in PDGF-B, and titanium dioxide increased TGF-alpha expression. Only asbestos caused increases in procollagen expression. No dust increased expression of tumor necrosis factor-alpha (TNF-alpha), fibronectin, or tropoelastin. Elevations in these factors coincided temporally with transport of particles into the epithelium and then to the subepithelial space. By in situ hybridization, TGF-beta gene expression was found in both the epithelium and subepithelial (interstitial) space, and PDGF-B and procollagen gene expression in the subepithelial space. Chemical analysis showed a small increase in hydroxyproline, a measure of collagen content, in asbestos-treated explants. We conclude that mineral dusts can induce airway wall fibrosis by directly upregulating proliferative and fibrogenic mediators as well as matrix components in the airway epithelium and interstitium, and that neither airspace nor circulating inflammatory cells are required for these effects. Different mineral dusts produce different patterns of reaction.

Is bone turnover a determinant of bone mass in rheumatoid arthritis?

OBJECTIVE

To study the relationship between bone turnover markers and bone mineral density in patients with rheumatoid arthritis.

METHODS

We studied 54 patients, 24 of whom were receiving low dose steroids, and compared them to 54 age and sex matched controls.

RESULTS

An 8.2% decrease of femoral neck bone mineral density (BMD) was found in patients not taking steroids compared with controls (confidence interval 1.2-15.3%). Serum markers of bone turnover -- namely, procollagen type I C-terminal propeptide (PICP) and procollagen type I N-terminal propeptide (PINP), which reflect bone formation, and procollagen type I C-terminal telopeptide, which reflects bone resorption -- were significantly increased compared with controls (p < 0.05, p < 0.01, p < 0.01, respectively). Both PINP levels and PICP levels were correlated with the femoral neck BMD as well as osteocalcin levels: R = -0.32 (p < 0.05), R = -0.29 (p < 0.05), and R = -0.42 (p < 0.01), respectively. The best independent predictors of bone mass (stepwise multiple regression analysis) at the femoral neck were steroid use, osteocalcin levels, age, height, the presence of rheumatoid factor, and the Health Assessment Questionnaire score, which explained 61.6% of the variance in femoral neck BMD.

CONCLUSION

Elderly patients with RA using steroids with severe disease and high levels of osteocalcin have marked osteoporosis at the hip.

Terfenadine and fexofenadine reduce in vitro ICAM-1 expression on human continuous cell lines

BACKGROUND

Epithelial cells and fibroblasts play an important role in allergic inflammation. Modulation of surface expression of adhesion molecules on epithelial cells by antiallergic drugs has been shown by both in vivo and in vitro studies.

OBJECTIVE

The aim of the study was to evaluate the effect exerted by terfenadine and fexofenadine on adhesion molecules expression (CD54/ICAM-1 and CD29) of a human continuously cultured conjunctival epithelial cell line (WK) and a fibroblast cell line (HEL).

METHODS

By means of flow cytometry analysis, we evaluated ICAM-1 and CD29 expression by WK and HEL epithelial cells in basal condition (at baseline) or after IFN gamma or TNF alpha stimulation in the presence or in the absence of terfenadine and fexofenadine. We also performed immunoenzymatic assays in order to evaluate soluble ICAM-1 released by WK cells and procollagen type I and III and IL6 released by HEL cells.

RESULTS

Terfenadine and fexofenadine significantly reduced ICAM-1 basal expression on WK cells at the concentration of 1 microg/mL and 50 microg/mL, respectively. In addition, both terfenadine and fexofenadine were able to decrease soluble ICAM-1 levels in IFN gamma-stimulated WK cells. On HEL fibroblasts, fexofenadine only was able to inhibit ICAM-1 upregulation induced by IFN gamma. Concerning the release of fibroblast products, we observed a dose-dependent decrease of spontaneous IL6 release only in the presence of fexofenadine.

CONCLUSION

This study shows that terfenadine and fexofenadine exert a biologic effect directly on epithelial cells and fibroblasts reducing ICAM-1 expression and partially reducing soluble ICAM-1 release.

Basic fibroblast growth factor-induced decrease in type I collagen gene transcription is mediated by B-myb

Basic fibroblast growth factor (bFGF), a member of the fibroblast growth factor family, potently induces increased vascular smooth muscle cell (SMC) proliferation and decreased expression of type I collagen. Recently, our laboratory demonstrated that, in bovine vascular SMCs, expression of B-myb, a member of the myb gene family, is dependent upon cellular growth state and that B-myb decreases alpha1(I) collagen promoter activity in transient transfection assays. Nuclear run-off analysis indicated that the decrease in alpha1(I) collagen mRNA level seen upon bFGF treatment was due to a decline in the rate of alpha1(I) procollagen gene transcription. Thus, we investigated the potential role of B-Myb in the down-regulation of type I collagen gene expression by bFGF. Using Northern blot analysis, we found that bFGF treatment of bovine aortic SMCs caused an increase in B-myb mRNA levels. Ectopic expression of B-myb decreased endogenous alpha1(I) collagen mRNA levels. Importantly, introduction of a B-myb antisense oligonucleotide prevented the drop in the alpha1(I) collagen mRNA levels seen upon treatment with bFGF. Together, these results indicate that B-myb mediates signals leading to the decreased rate of alpha1(I) collagen gene transcription caused by bFGF.

Effect of high-glucose concentrations on the expression of collagens and fibronectin by fibroblasts in culture

Extracellular matrix macromolecules such as collagen and fibronectin are progressively altered during aging and age-related diseases like diabetes. We investigated the effect of high-glucose concentration (mimicking diabetic conditions) and the influence of in vitro cell aging [comparing 4th-passage fibroblasts (P4) to 15th-passage fibroblasts (P15)] on collagen and fibronectin synthesis. Fibroblasts were incubated at postconfluency with radiolabeled precursors, [3H] proline for collagen, [35S] methionine for fibronectin. We report that in control conditions (5 mM glucose) collagen III production increased with in vitro cell aging. High glucose concentrations (10 and 15 mM) increased specifically collagen III synthesis both at the mRNA and protein levels, without alteration of collagen I production in P4 and P15 cells. Fibronectin synthesis was also increased both during in vitro cell aging and in high glucose-treated P4 fibroblasts. Taken together, these data suggest similarities between changes of phenotypic expression of collagen and fibronectin induced by in vitro cell aging and conditions imitating diabetes.