Effect of the menopause and hormone replacement therapy on the carboxy-terminal pyridinoline cross-linked telopeptide of type I collagen

Clinical value of serum bone resorption markers for predicting clinical outcomes after use of bone modifying agents in metastatic bone tumors: A prospective cohort study

Bone modifying agents (BMAs) have become a standard treatment to prevent skeletal-related events (SREs) in bone metastases (BMs). The aim of our study is to determine the clinical value of serum bone resorption markers for predicting clinical outcomes after using BMAs in patients with BM. Patients were enrolled between May 2013 and October 2017 at the Nagoya University Hospital, Japan. We prospectively observed changes in pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and tartrate-resistant acid phosphatase 5b (TRACP-5b) during treatment with BMAs. The relationship between serum markers before and after treatment and clinical outcomes such as progression of bone disease (BD), SREs and overall survival (OS) were evaluated. Pearson chi-square test and Kaplan-Meier product limit methods were used for analysis. Sixty-seven patients were analyzed. The primary tumor sites were 21 lung, 16 breast and 30 others. Forty and 27 patients were treated with Denosumab and Zoledronic acid, respectively. Progression of BDs, SREs and death were observed in 10, 16 and 31 cases, respectively. The median follow-up period after using BMAs was 12.3 (range 0.3-66.3) months. ICTP at 3-4 weeks was significantly correlated with increasing BD progression, SREs and death after treatment in both the whole and lung cancer cohorts. Base line ICTP and TRACP-5b were also associated with increasing BD progression in the whole cohort. Our study showed that early posttreatment ICTP is useful for predicting BD progression, SREs and OS after use of BMAs in patients with BM and even in patients with lung cancer BM.

Age-related reference intervals for bone turnover markers from an Australian reference population

BACKGROUND

This study was performed to establish age-related serum reference intervals for procollagen type I N-propeptide (P1NP) and type I collagen C-telopeptide (CTx) in the Australian population.

METHODS

Fasting sera from 1143 males (mean age 60 years; range 20-97 years) and 1246 females (mean age 53 years; range 20-93 years) who participated in the Geelong Osteoporosis Study were analysed for CTx and P1NP using the automated Roche Modular Analytics E170 analyser.

RESULTS

Optimal age-related reference intervals were based on the central 90% of the distribution. The male CTx reference interval was divided into three age groups. For men aged 25 to 40 years, the interval was 170-600 ng/L; 40 to 60 years, the interval was 130-600 ng/L; and for men aged greater 60 years the interval was 100-600 ng/L. For P1NP the male reference interval was 15-80 μg/L for men aged between 25 to 70 years. In men greater than 70 years of age values were higher possibly due to increased bone turnover. High values are frequently seen for both CTx and P1NP in males aged younger than 25 years. This is probably due to bone growth that is not completely finalised. The female CTx reference interval was divided into four age groups. For women aged less than 30 years, the interval was 150-800 ng/L; 30-39 years, the interval was 100-700 ng/L; 40-49 years, the interval was 100-600 ng/L; and for women aged 50 years or more the interval was 100-700 ng/L. The female P1NP reference interval was divided into four age groups. For women aged less than 30 years, the interval was 25-90 μg/L; 30-39 years, the interval was 15-80 μg/L; 40-49 years, the interval was 15-60 μg/L; and for women aged 50-69 years the interval was 15-75 μg/L. In women greater than 70 years of age values were higher possibly due to increased bone turnover.

CONCLUSION

Values obtained from this large study provide sound age-related reference intervals for serum P1NP and CTx values in the Australian population.

The role of bone turnover markers in monitoring treatment in postmenopausal osteoporosis

Bone metabolism is assessed using biochemical bone turnover markers (BTM). BTM reflect the metabolic effect of drugs on bone turnover, help to establish the lowest dose inducing the largest change in the BTM, predict treatment-related reduction in fracture risk, and are helpful in bridging studies. Changes in BTM during anti-osteoporotic therapy depend on the cellular mechanism of action of the drug, degree of change in bone turnover rate and route of administration. BTM help to establish the optimal dose of anti-osteoporotic drugs because treatment-related changes in BTM are more rapid compared with change in BMD. A greater decrease in BTM levels during the first year of tantiresorptive treatment is associated with greater antifracture efficacy over 3 years. According to preliminary data, measurement of BTM can improve persistence with anti-resorptive treatment. The use of BTM to monitor anti-osteoporotic therapy in "real life" is limited at this stage.

Nomegestrol acetate may enhance the skeletal effects of estradiol on biochemical markers of bone turnover in menopausal women after a 12-week treatment period

OBJECTIVE

To compare the effects of a 12-week treatment with 17ss-estradiol given alone and in sequential combination with 3.75 mg of nomegestrol acetate (Naemis), or a placebo on biochemical markers of bone turnover in menopausal women.

PATIENTS AND METHODS

A double-blind, randomized, placebo and estradiol-controlled multicenter study was conducted. A total of 176 patients who had been menopausal for 1-10 years, hysterectomized or not, having no contraindications to hormone replacement therapy, without any risks factors for osteoporosis, received one of these treatments during 12 weeks: placebo, 1.5 mg estradiol (E(2)) or 1.5 mg E(2)/3.75 mg nomegestrol acetate (E(2)/NOMAC). The primary efficacy variables were the change in bone markers (total alkaline phosphatase, bone alkaline phosphatase and osteocalcin; urinary type-I collagen peptides).

RESULTS

The four biochemical markers decreased only in the E(2)/NOMAC group. Bone alkaline phosphatase, osteocalcin and urinary type-I collagen peptides decreased in the E(2) group. For both active treatment groups compared to the placebo group, the changes were statistically significant after a 12-week treatment. There were no statistically significant differences between the E(2) and the E(2)/NOMAC groups except for total serum alkaline phosphatase, whose mean value decreased in the E(2)/NOMAC group but increased slightly in the E(2) group (p < 0.001). Furthermore, after a 6-week treatment, the changes in biochemical markers of bone turnover were similar to those found after 12 weeks. Safety data were satisfactory with regard to estradiol given alone or in combination with nomegestrol acetate.

CONCLUSION

These results demonstrated that 1.5 mg E(2) is effective in reducing bone turnover in postmenopausal women and proved that the combination of 1.5 mg E(2) and 3.75 mg nomegestrol acetate has no deleterious effect on bone remodelling.

Biomarkers of bone health and osteoporosis risk

The assay features of biochemical markers of bone turnover have markedly improved in the past few years. The most sensitive and specific markers of bone formation include serum bone alkaline phosphatase, total osteocalcin (including the intact molecule and the large N-mid fragment) and the procollagen type I N-terminal propeptide assay. Among the various markers of bone resorption, measurements of the urinary excretion of N- and C-terminal cross-linked telopeptides) and of serum C-terminal cross-linked telopeptides are the most sensitive and specific. Markers of bone turnover can be used to predict the rate of bone loss in post-menopausal women and can also be used to assess the risk of fractures. In osteoporosis-treatment studies (with alendronate, risedronate, raloxifene) markers of bone turnover appear even more strongly associated with fracture risk reduction than bone mineral density (BMD). These observations support the use of markers of bone turnover as surrogates for fracture risk reduction, perhaps even more so than BMD. Bone markers can also be used to monitor the efficacy of antiresorptive therapy such as hormone-replacement therapy, raloxifene and bisphosphonates in individual patients. Furthermore, they have also proved to be helpful in monitoring the response to nutritional interventions and have the advantage over BMD in that they provide information about mechanism of effect and changes are often observed much more rapidly.

The amino- and carboxyterminal cross-linked telopeptides of collagen type I, NTX-I and CTX-I: a comparative review

Bone diseases such as osteoporosis or bone metastases are a continuously growing problem in the ageing populations across the world. In recent years, great efforts have been made to develop specific and sensitive biochemical markers of bone turnover that could help in the assessment and monitoring of bone turnover. The amino- and carboxyterminal cross-linked telopeptides of type I collagen (NTX-I and CTX-I, respectively) are two widely used bone resorption markers that attracted great attention due to their relatively high sensitivity and specificity for the degradation of type I collagen, and their rapid adaptation to automated analyzers. However, the clinical performance of both markers differs significantly depending on the clinical situation. These differences have caused considerable confusion and uncertainty. If used correctly, both markers have great potential to improve the management of many bone diseases. We here review the biochemistry, analytical background and clinical performance of NTX-I and CTX-I, as documented in the accessible literature until March 2008.

Clinical application of biochemical markers of bone turnover

With the ageing population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to every day clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis and follow-up of such pathologies have markedly grown. Together with clinical and imaging techniques, biochemical tests play an important role in the assessment and differential diagnosis of metabolic bone disease. In recent years, the isolation and characterisation of cellular and extracellular components of the skeletal matrix have resulted in the development of molecular markers that are considered to reflect either bone formation or bone resorption. These biochemical indices are non-invasive, comparatively inexpensive and, when applied and interpreted correctly, helpful tools in the diagnostic and therapeutic assessment of metabolic bone disease. This review provides an overview of the current evidence regarding the clinical use of biochemical markers of bone remodelling in bone disease, with an emphasis on osteoporosis.

Bone resorption and osteoporotic fractures in elderly men: the dubbo osteoporosis epidemiology study

Among the potential risk factors for fragility fractures, bone turnover is considered an important determinant. In a case-cohort control study of 151 elderly men followed prospectively over 6.3 years, high bone resorption as assessed by S-ICTP was associated with increased risk of osteoporotic fracture, independent of BMD. Combining measurements of BMD and bone turnover may improve fracture prediction in elderly men.

INTRODUCTION

Approximately one-third of osteoporotic fractures occur in men. Among the potential risk factors for fragility fractures, bone turnover is considered an important determinant. The association between fracture risk and rates of bone turnover has not been well established in men. We examined this relationship in elderly community-dwelling men.

MATERIALS AND METHODS

This case-cohort control study included 50 men with incident low-trauma fractures (cases; age, 72.3 +/- 6.7 years) and 101 men without fracture (controls; age, 70.4 +/- 4.1 years), who have been prospectively followed in the Dubbo Osteoporosis Epidemiology Study for a median of 6.3 years (range, 2-13 years). BMD at the lumbar spine (LSBMD) and at the femoral neck (FNBMD) and markers of bone turnover were measured at baseline. Bone resorption was assessed by measuring nonfasting serum concentrations of the carboxyterminal cross-linked telopeptide of type I collagen (S-ICTP) and of a linear octapeptide derived from the carboxyterminal type I collagen telopeptide (S-CTX). Bone formation was assessed by measuring the serum levels of the aminoterminal propeptide of type I procollagen (S-PINP).

RESULTS

Men with subsequent fractures had lower BMD at baseline, both at the femoral neck and the spine, lower dietary calcium intake, and higher S-ICTP levels than age-and weight-matched controls. Smoking habits, S-CTX, and S-PINP did not differ between groups. Based on univariate regression analyses, S-ICTP (relative risk [RR] for 1 SD change: 1.8; 95% CI, 1.4-2.3) and serum creatinine levels (RR, 1.4; 95% CI, 1.1-1.7) were associated with increased risk of fracture. In multivariate regression analyses, S-ICTP (RR, 1.4; 95% CI, 1.0-1.9) and FNBMD (RR, 1.8; 95% CI, 1.4-2.3) remained independent predictors of fracture risk. Men within the highest quartile of S-ICTP had a 2.8-fold (95% CI 1.4-5.4) increased risk of fracture compared with those in the lowest quartile. The incidence of osteoporotic fractures was 10 times higher in men with high S-ICTP and low FNBMD compared with men with low S-ICTP and high FNBMD. Of the fracture risk in the population, 20% was attributable to high S-ICTP and low FNBMD, and S-ICTP contributed 17% to this increased risk.

CONCLUSION

High bone resorption is associated with an increased risk of osteoporotic fracture in elderly men, independent of BMD. Combining measurements of BMD and bone turnover, which correlated with fracture in this cohort, could improve fracture risk prediction in elderly men.

Markers of collagen synthesis and degradation in urogenital tissue from women with and without stress urinary incontinence

AIMS

Multiparity and obesity are risk factors for stress urinary incontinence (SUI), but collagen synthesis and metabolism in the urogenital tissue itself may also affect its function and control of micturition. Whether changes in synthesis or degradation of collagen are part of the etiology of SUI is not known and published studies show diverging results. The aims of the present study was to investigate collagen turnover in urogenital tissue in women with SUI (n=71) and in urologically healthy women (n=31).

METHODS

Markers of collagen synthesis and breakdown, the carboxy-terminal propeptide of type I procollagen (PICP), the carboxy-terminal telopeptide of type I collagen (ICTP), and the amino-terminal propeptide of procollagen III (PIIINP) were assayed in urogenital tissue homogenates and peripheral serum.

RESULTS

In the total clinical material SUI patients were significantly older, had a significantly higher body mass index (BMI) and significantly lower serum PICP and tissue ICTP levels than the controls. When healthy controls were compared with SUI patients matched for age, BMI, parity, and hormonal/menopausal status (31 women in each group), the SUI patients had significantly lower serum concentrations of PICP and significantly lower tissue concentrations of PIIINP and ICTP than the controls. Within the total material of SUI patients, post-menopausal women with weak and strong HRT and pre-menopausal women had significantly lower S-ICTP concentrations than untreated post-menopausal patients. Significant negative correlations to parity were found for T-PIIINP and T-PICP and to BMI for T-ICTP.

CONCLUSIONS

The low tissue collagen marker levels in women with SUI suggest a reduced collagen turnover, which may negatively affect tissue strength and elasticity.

Hormones and bone health in postmenopausal women

Although it has been known for some time that estrogen deficiency is a major pathogenetic factor for osteoporosis related fractures among postmenopausal women, the capability of estrogen (with or without a progestin) to prevent fractures has often been questioned. The publication of the data from the two hormone clinical trials of the Women's Health Initiative lays that discussion to rest. In both studies what have been considered a standard dose of conjugated estrogen with or without medroxyprogesterone acetate significantly reduced the risk of all fractures, including clinical vertebral fractures and hip fracture, in a population of postmenopausal women, average age 63 yr, not selected for osteoporosis by BMD. These results are particularly impressive given the difficulty of finding a fracture benefit in lower risk populations with other anti-resorptive agents. Surrogate data on lower doses of hormone therapy suggest a fracture benefit would be seen if studies were to be done. The other outcomes in WHI make it important to define appropriate clinical guidelines for use of hormone therapy for prevention of fractures in postmenopausal women.

Assay for cross-linked carboxyterminal telopeptide of type I collagen (ICTP) unlike CrossLaps assay reflects increased pathological degradation of type I collagen in rheumatoid arthritis

We compared the ability of assay for cross-linked carboxyterminal telopeptide of type I collagen (ICTP) and CrossLaps assay to reflect increased pathological degradation of type I collagen in serum and synovial fluid samples of patients with rheumatoid arthritis (RA; n = 40). ICTP and CrossLaps concentrations were correlated with each other and with markers of collagen synthesis (PINP and PIIINP, amino terminal propeptides of type I and type III procollagens, respectively) and with markers of inflammation, i.e., C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Serum ICTP was increased in half of the RA patients, whereas CrossLaps assays were increased only occasionally. Serum ICTP correlated with the other markers of collagen metabolism as well as with CRP and ESR. Serum CrossLaps correlated only with PINP and ICTP, but not with serum PIIINP, CRP or ESR. Two patients had false-positive reactions in the CrossLaps assay due to the rheumatoid factor. The ICTP and CrossLaps antigens were clearly separate peaks in gel filtration analysis. The CrossLaps assay is able to detect the same ICTP antigen, but not vice versa. The ICTP assay reflects increased matrix metalloproteinase-mediated collagen degradation in joints in RA. In contrast, the physiological cathepsin K-mediated bone resorption measured by the CrossLaps assay was only occasionally increased.

Biochemical markers of bone remodeling

Because of the aging population in most countries, disorders of bone and mineral metabolism are becoming increasingly relevant to everyday clinical practice. Consequently, the interest in, and the need for effective measures to be used in the screening, diagnosis, and follow-up of such pathologies has markedly grown. Together with clinical and imaging techniques, laboratory tests play an important role in the assessment and differential diagnosis of metabolic bone disease.

Bone resorption versus estrogen loss following oophorectomy and menopause

OBJECTIVES

To investigate if menopause and oophorectomy may represent different risk factors for bone resorption/loss.

METHODS

The urinary levels of pyridinoline (Pyr) and deoxypyridinoline (D-pyr), the serum levels of type I carboxy-terminal pyridinoline cross-linked telopeptide (ICTP), and lumbar bone mineral density (BMD), were compared in 80 Japanese women after menopause or oophorectomy. These women were divided into four groups of 20 women each as follows: early postmenopausal stage (early physiologic menopause < 3 years before study entry); late postmenopausal stage (physiologic menopause > or = 3 years before study entry); early postoophorectomy stage (oophorectomy < or = 03 years before study entry); or late oophorectomy stage (oophorectomy > 3 years before study entry).

RESULTS

Lumbar BMD was significantly lower in the late groups compared to their respective early groups and was lowest in the late postoophorectomy group. The ratio of D-pyr/creatinine (Cr) was not significantly different among the four groups. The ratio of Pyr/Cr was significantly higher in the early postoophorectomy subjects compared with either late group. The serum level of ICTP was significantly higher in the early postoophorectomy group compared to all other groups.

CONCLUSIONS

These findings suggest that serum ICTP may be useful in detecting changes in bone resorption after oophorectomy and that women are at greater risk for bone resorption after oophorectomy than after physiologic menopause, although this difference appears to diminish with time.

Serum tartrate-resistant acid phosphatase isoforms in rheumatoid arthritis

OBJECTIVES

Our objective was to evaluate the significance and source of serum tartrate-resistant acid phosphatase (TRACP) in patients with rheumatoid arthritis (RA).

METHODS

Thirty-five RA, 32 osteoarthritis (OA) and 16 control subjects were studied. Serum TRACP-5b activity and total TRACP protein were determined by immunoassay. TRACP isoforms were analyzed by non-denaturing polyacrylamide gel electrophoresis (PAGE). Serum bone alkaline phosphatase (BAP), cross-linked N-terminal telopeptides (NTx), and C-terminal telopeptides (ICTP) of type I collagen were estimated as markers of bone turnover. C-reactive protein (CRP) was measured as a marker of chronic inflammation. Macrophages and dendritic cells (DC) were developed from peripheral blood monocytes. Cell lysates and culture supernatants were analyzed for TRACP isoforms by immunoassay and PAGE.

RESULTS

In RA, mean TRACP-5b activity was normal, but median total TRACP protein was increased twofold (p<0.001). In OA, TRACP-5b activity and protein were normal. In RA, TRACP-5b activity correlated weakly with ICTP (r=0.56) while TRACP protein levels correlated weakly with NTx (r=0.43). Additionally, TRACP protein, but not TRACP-5b activity correlated significantly with CRP (r=0.42). Macrophage and DC lysates contained TRACP-5b, while tissue culture supernatants contained TRACP-5a.

CONCLUSIONS

Increased total TRACP protein in RA sera was probably due to TRACP-5a and not derived from osteoclasts. Rather, it could be a secreted product of inflammatory macrophages and DC.

Changes of biochemical bone markers during the menopausal transition

We present data on the changes of the bone formation markers osteocalcin (OC), bone-specific alkaline phosphatase (bone ALP) and bone sialoprotein (BSP), as well as the resorption markers pyridinoline (PYD), deoxypyridinoline (DPD), C- and N-terminal telopeptide cross-linked collagen type I (CTX, NTX), and tartrate-resistant acid phosphatase type 5b (TRACP) at five time points during the course of two years in healthy premenopausal, perimenopausal and early postmenopausal women. The prospective study showed that CTX (p<0.001), NTX (p=0.001) and TRACP (p=0.001), as well as bone ALP (p=0.009) and OC (p=0.052), were significantly increased already in the transition period from peri- to postmenopause. The pyridinium crosslinks indicated an increased collagen degradation rate already in the perimenopause (PYD, p=0.017; DPD, p=0.054). Significant inverse correlations with the two years changes of the bone mineral density were found for bone ALP, CTX, OC and DPD in the perimenopausal group. The measurement of a comprehensive panel of biochemical bone markers clearly shows that metabolic changes in bone metabolism appear pronounced in the perimenopause, a period still presenting satisfactory estrogen supply. Thus, the perimenopause is an important phase for a contingent development of osteoporosis.

Bone metabolism during the perimenopausal transition: a prospective study

OBJECTIVE

Changes in biochemical markers of bone formation and resorption were followed over the course of 1 year in premenopausal, perimenopausal and early postmenopausal women.

METHODS

Sixty-four subjects were analyzed, grouped according to their menstrual pattern, menopausal complaints and endocrinological parameters to be premenopausal (n=20), perimenopausal (n=24) or early postmenopausal (n=20). The parameters studied at four visits during the 12-month study period were the urinary pyridinium cross-links pyridinoline (PYD) and deoxypyridinoline (DPD), and N-terminal telopeptide (NTX) as bone resorption markers, as well as osteocalcin (OC) and bone-specific alkaline phosphatase (BAP) in serum, representing bone formation. The longitudinal changes over time as well as intergroup differences were analyzed using generalized estimating equations (GEE) in connection with Wald statistics.

RESULTS

Over the course of 1 year BAP levels decreased in the late premenopausal group (P<0.05). The perimenopausal group exhibited significant changes of PYD, DPD and OC (P<0.01), NTX levels were higher than in premenopause. Postmenopausal subjects had elevated NTX values, while PYD and DPD levels remained close to the perimenopausal range. Only for OC a time effect was seen during postmenopause.

CONCLUSIONS

Changes in bone turnover already begin in late premenopause, when decreased bone formation may precede increased bone resorption. The rise of NTX from late premenopause through early postmenopause indicates diagnostic sensitivity of this parameter to changes in bone metabolism induced by estrogen withdrawal. PYD and DPD do not follow this pattern, but change significantly with time during perimenopause to then remain largely unchanged in early postmenopause.

Estrogen reduces the depth of resorption pits by disturbing the organic bone matrix degradation activity of mature osteoclasts

Decreased E2 levels after menopause cause bone loss through increased penetrative resorption. The reversal effect of E2 substitution therapy is well documented in vivo, although the detailed mechanism of action is not fully understood. To study the effects of E2 on bone resorption, we developed a novel in vitro bone resorption assay in which degradation of inorganic and organic matrix could be measured separately. E2 treatment significantly decreased the depth of resorption pits, although the area resorbed was not changed. Electron microscopy further revealed that the resorption pits were filled with nondegraded collagen, suggesting that E2 disturbed the organic matrix degradation. Two major groups of proteinases, matrix metalloproteinases (MMPs) and cysteine proteinases, have been suggested to participate in organic matrix degradation by osteoclasts. We show here that MMP-9 released a cross-linked carboxyl-terminal telopeptide of type I collagen from bone collagen, and cathepsin K released another C-terminal fragment, the C-terminal cross-linked peptide of type I collagen. E2 significantly inhibited the release of the C-terminal cross-linked peptide of type I collagen into the culture medium without affecting the release of cross-linked carboxyl-terminal telopeptide of type I collagen in osteoclast cultures. These results suggest that organic matrix degradation is initiated by MMPs and continued by cysteine proteases; the latter event is regulated by E2.

Prediction of disease progression in early rheumatoid arthritis by ICTP, RF and CRP. A comparative 3-year follow-up study

OBJECTIVE

To test the predictive value of the cross-linked carboxyterminal telopeptide of type I collagen (ICTP; a marker of type I collagen degradation), rheumatoid factor (RF) and C-reactive protein (CRP) for disease progression in patients with early rheumatoid arthritis (RA) METHOD: We tested the value of baseline values of RF, CRP and ICTP for the prediction of radiological joint progression over 3 yr in 63 consecutive patients with early RA who were treated with the 'saw-tooth strategy'.

RESULTS

Age- and sex-adjusted risks as odds ratios (95% confidence intervals) of elevated serum ICTP, RF positivity and increased CRP for progressive joint disease (defined as an increase of > 20 in Larsen's index on radiographs of the hands and feet) were 3.9 (1.3, 11.9), 3.9 (1.0, 15.5) and 2.6 (0.9, 7.5), respectively. Better prediction was achieved when the tests were used in combination, and where there was both elevated ICTP and positive RF the odds ratio was 9.1 (2.5, 32.9). This test combination showed good sensitivity and specificity (71 and 77%, respectively), with a positive predictive value of 65% and a likelihood ratio of 3.1.

CONCLUSION

This kind of risk profile, in which the tests used reflect different aspects of the disease process, may be useful in early disease assessment to find patients who will need the most active drug therapy.

Immunochemical characterization of assay for carboxyterminal telopeptide of human type I collagen: loss of antigenicity by treatment with cathepsin K

The assay for the cross-linked carboxyterminal telopeptide of type I collagen (ICTP) has been shown to reflect increased type I collagen degradation in such pathological conditions as bone metastases and rheumatoid arthritis, but to be rather insensitive to the changes in physiological bone collagen turnover (e.g., induced by estrogen or bisphosphonate treatment). To determine the reasons for this discrepancy we localized the antigenic determinant recognized by the ICTP assay and studied the effects of two major osteoclastic proteinases, cathepsin K (EC 3.4.22.38) and matrix metalloproteinase-9 (MMP-9; gelatinase B; EC 3.4.24.35), on immunoreactivity. The antigenic determinant was shown to reside within the hydrophobic phenylalanine-rich regions of the carboxyterminal telopeptides of the two alpha1 chains of human type I collagen, situated between the triple helical domain and the lysine-derived trivalent cross-link. This conclusion was based on differences between the amino acid sequences and cross reactivities of the corresponding human and bovine antigens before and after proteolytic treatments with chymotrypsin. A trivalent cross-link is necessary for providing such a structure, because the divalently cross-linked and monomeric natural and synthetic peptides from the same region, but containing only one phenylalanine-rich sequence, showed poor immunoreaction. Recombinant human cathepsin K cleaved the trivalently cross-linked ICTP structure at two sites between the phenylalanine-rich region and the cross-link, destroying the reactivity with ICTP antibodies. On the contrary, the treatment of isolated ICTP by the matrix metalloproteinases MMP-9 (gelatinase B), MMP-1 (collagenase 1), or MMP-13 (collagenase 3) had no effect on the immunoreaction. Our results indicate that the increased circulating concentrations of ICTP found in several clinical situations are most likely produced by matrix metalloproteinases, whereas cathepsin K-mediated, osteoclastic bone resorption destroys ICTP antigenicity.

The effects of six months of treatment with a low-dose of conjugated oestrogens in menopausal women

OBJECTIVE

Hormone replacement therapy (HRT) is usually prescribed as medium- to high-dose formulations. Little is known, however, about dose-dependency of oestrogen effects on plasma hormone levels, markers of cardiovascular risk in lipid metabolism and the haemostatic system, or markers of bone turnover.

SUBJECTS AND DESIGN

In an open trial, three groups of 12 or 13 healthy, non-obese postmenopausal women received conjugated equine oestrogens (CEE) for 6 months at doses of 0.3 mg/day (group 1), 0.6 mg/day (group 2) or 1.25 mg/day (group 3). From day 1 to day 10, CEE was administered alone, and from day 11 to day 21, in combination with 5 mg of medrogestone. Each treatment cycle was followed by a pause of 7 days. Fasting blood samples were obtained before treatment as well as on days 10, 21 and 28 of the first, third and sixth months on treatment. All results obtained on day 10 were grouped together as phase A, on day 21 as phase B, and on day 28 as phase C.

MEASUREMENTS

Plasma concentrations of oestradiol (E), dehydroepiandrosterone sulphate (DHEA-S), total testosterone (T), FSH, PRL, sex hormone binding globulin (SHBG), type I procollagen propeptide (PICP) and the cross-linked carboxyterminal telopeptide of type I collagen (ICTP), total cholesterol, HDL-cholesterol, triglycerides (TG), apolipoprotein (apo) A-1, apo B, lipoprotein(a)[Lp (a)], fibrinogen, factor VIIc and plasminogen activator inhibitor 1 (PAI-1) were evaluated with commercially available kits.

RESULTS

Dose-dependently, the three regimens increased E, SHBG and factor VIIc activity and decreased FSH, DHEAS, cholesterol, LDL-cholesterol and apoB. HDL-cholesterol and apoA-1 were slightly decreased in group 1 but increased in groups 2 and 3. The high CEE dosage in group 3 resulted in a significant increase of TG and decrease of Lp(a) and PAI-1. Markers of bone turnover were not significantly changed by any CEE dosage.

CONCLUSIONS

Six months of treatment with 0.3 mg/day of conjugated equine oestrogen significantly lowers serum levels of total cholesterol and LDL-cholesterol without causing the adverse increases of triglycerides or factor VIIc, which were observed at higher doses. However, this low-dose treatment did not yield the maximal LDL-cholesterol lowering effect. Moreover, the positive effects of HRT on HDL-cholesterol, apolipoprotein A-I, lipoprotein (a) and plasminogen activator inhibitor-1 required at least the medium dose of 0.6 mg conjugated equine oestrogens per day. Therefore, further studies are needed to determine which dose of conjugated equine oestrogens has the optimal effect on cardiovascular risk and bone turnover.

Influence of estrogen-progestin treatment on back pain and disability among slim premenopausal women with low lumbar spine bone mineral density. A 2-year placebo-controlled randomized trial

STUDY DESIGN

A 2-year randomized controlled trial.

OBJECTIVES

To examine the possible preventive or aggravating effect of estrogen-progestin treatment on the back symptoms of slim premenopausal women with low lumbar spine bone mineral density.

SUMMARY OF BACKGROUND DATA

The incidence of back pain, sciatica, or both starts to increase clearly among 45-54-year-old Finnish women.

METHODS

Forty-eight 39- to 49-year-old premenopausal women with a body mass index of 21 or less and a lumbar spine bone mineral density (L2-L4) of 1.1 +/- 1 g/cm3 or less compared with the normative population were recruited into the study. The women were assigned randomly to receive either estradiol-noretisteron acetate treatment or placebo. Back pain, symptoms, and disability were assessed with the Million and Oswestry questionnaires and pain drawings during the follow-up period at 0, 12, and 24 months. Inquiry also was made concerning previous back pain and sciatica history.

RESULTS

There was a statistically significant decrease in nighttime back pain (P < 0.001) and the total Oswestry disability scores (P < 0.004) in the hormone-treated group compared with the control group during the follow-up, but no statistically significant differences were found in daytime back pain. At baseline, the cumulative incidence in a history of pain radiating from the buttock to the foot in this osteopenic study group was 31/48, (64.5%; 95% CI 50.5-78.6), which is much more than the predicted 20/48, (42.4%; 95% CI 39.0-45.7) at this age according to a previous population study. The cumulative incidence of at least one back pain episode 44/48, (91.7%; 95% CI 83.6-99.8) was somewhat higher in these participants than was predicted for a comparative population of women this age, 38/48 (79.2%; 95% CI 70.2-87.3).

CONCLUSIONS

It seems that this regimen may have alleviating effects on nighttime back pain and functional back disability in slim osteopenic premenopausal women.

Low incidence of osteoporosis in a two year follow-up of early community based patients with rheumatoid arthritis

52 patients with early rheumatoid arthritis (RA) were followed with regular measurements of bone mineral density (BMD) and serum markers of type I collagen metabolism in order to determine whether they develop osteoporosis during the first two years of the disease course and if the changes in type I collagen metabolites reflect the alterations in BMD. The mean percentage BMD change over the first year of follow-up was -0.91 for lumbar spine (LS) and -0.76 for femoral neck (FN); the corresponding figures from 0 to 24 months was -1.3 and -0.8, respectively. During the follow-up, only five patients developed osteoporosis by the Z-score definition (<-1). If defined by T-score (<-2.5) none of the patients developed osteoporosis. The BMD change correlated neither with the clinical parameters of disease activity nor with the markers of collagen metabolism. However, the BMD change in FN was associated with the cumulative corticosteroid dose (r=-0.31, p <0.05, 95% CI -0.54 to -0.04). Reasons for the lack of accelerated bone loss in our series are open to various interpretations. This series was community based and most of the patients had mild RA. The patients were also actively treated and their physical function did not deteriorate.

Galactosylhydroxylysine and pyridinium cross links in monitoring the bone response to hormone replacement therapy

Aim of the study was to compare urinary galactosyl-hydroxylysine (GHyl), deoxypyridinoline (D-Pyr) and pyridinoline (Pyr) before and after 5 to 9 months of hormone replacement therapy (HRT) in postmenopausal women. The urinary markers were measured by HPLC in the second void of fasting samples and were expressed as ratio to creatinine. GHyl was also expressed as a ratio to glucosylgalactolysyl-hydroxylysine (GGHyl). After short-term hormone replacement therapy, urinary D-Pyr fell significantly, but Pyr and GHyl, also when expressed as a ratio to GGHyl, remained unmodified. We conclude that GHyl and Pyr are not useful markers in monitoring the bone response to HRT in postmenopausal women.

New biochemical markers of bone resorption derived from collagen breakdown in the study of postmenopausal osteoporosis

The aim of this work was to perform a comparative study between three recently developed biochemical markers of bone resorption derived from collagen metabolism--(1) total urinary free pyridinolines (Pyr), (2) serum pyridinoline cross-linked carboxy-terminal telopeptides of type I collagen (ICTP) and (3) a urinary-specific sequence for a part of the C-telopeptide of the alpha 1 chain of type I collagen (CTX)--in the diagnosis and follow-up of postmenopausal osteoporosis. Results were also evaluated relative to the classical biochemical marker urinary hydroxyproline (Hyp). The study included 20 untreated osteoporotic postmenopausal women (OSP), age 60 +/- 6 years, range 46-69 years; 27 osteoporotic postmenopausal women treated (OSP-T) by cyclic therapy with disodium etidronate, 25-hydroxyvitamin D and calcium for a period between 3 months and 4 years (25 +/- 15 months), age 59 +/- 7 years, range 41-67 years; 17 osteopenic postmenopausal women, age 57 +/- 6 years, range 46 +/- 68 years; and 29 healthy control postmenopausal women, age 56 +/- 7 years, range 41-70 years. The diagnostic criterion for postmenopausal osteoporosis was a bone mineral density (BMD) (Hologic QDR-1000) in lumbar spine and/or femoral neck more than 2 SD below the mean value corresponding to an age- and sex-matched healthy control group. For inclusion in the osteopenic group BMD values had to be between 1 and 2 SD below the mean BMD value corresponding to the control group. We found a significant increase (p < 0.01) in the levels of Pyr/Cr and CTX/Cr (Cr = creatinine) in OSP patients with respect to the control group and we did not observe any significant difference between control and OSP-T or osteopenic women. It is interesting to note that there was a mean increase in CTX/Cr in OSP patients of 101% of the control values, while the mean increase found in Pyr/Cr concentration was only 33%. However, we did not find significant differences in the concentrations of ICTP and Hyp/Cr between groups. In a comparison of Pyr/Cr and CTX/Cr, urinary CTX showed the higher diagnostic accuracy, as can be deduced from the receiver operating characteristic (ROC) curves. CTX sensitivity was 40% with a specificity of 100%, whereas the sensitivity was 25% for urinary Pyr/Cr. In conclusion, the results of the present work suggest that in osteoporotic women CTX has the highest diagnostic accuracy among the markers of bone resporption studied.