Impact of the hypoxic microenvironment on spermatogonial stem cells in culture

The stem cell niche plays a crucial role in the decision to either self-renew or differentiate. Recent observations lead to the hypothesis that O2 supply by blood and local O2 tension could be key components of the testicular niche of spermatogonial stem cells (SSCs). In this study, we investigated the impact of different hypoxic conditions (3.5%, 1%, and 0.1% O2 tension) on murine and human SSCs in culture. We observed a deleterious effect of severe hypoxia (1% O2 and 0.1% O2) on the capacity of murine SSCs to form germ cell clusters when plated at low density. Severe effects on SSCs proliferation occur at an O2 tension ≤1% and hypoxia was shown to induce a slight differentiation bias under 1% and 0.1% O2 conditions. Exposure to hypoxia did not appear to change the mitochondrial mass and the potential of membrane of mitochondria in SSCs, but induced the generation of mitochondrial ROS at 3.5% and 1% O2. In 3.5% O2 conditions, the capacity of SSCs to form colonies was maintained at the level of 21% O2 at low cell density, but it was impossible to amplify and maintain stem cell number in high cell density culture. In addition, we observed that 3.5% hypoxia did not improve the maintenance and propagation of human SSCs. Finally, our data tend to show that the transcription factors HIF-1α and HIF-2α are not involved in the SSCs cell autonomous response to hypoxia.

Type II collagen peptide Coll2-1 is an actor of synovitis

OBJECTIVE

We evaluated the ability of Coll2-1, a type II collagen peptide, to activate pro-inflammatory pathways in synovial cells and to induce arthritis in Lewis rats.

METHOD

Human synoviocytes and chondrocytes from knee OA patients were cultured for 24 h with/without Coll2-1 and/or purified immunoglobulin G (AS0619) binding specifically this peptide, and/or CLI-095, a TLR-4 signaling inhibitor and/or apocynin and diphenyleneiodonium, Reactive oxygen species (ROS) production inhibitors. The Interleukin (IL)-8 and Vascular Endothelium Growth Factor (VEGF) expression, the IL-8 production, the IκB-α and p65 phosphorylation and ROS were evaluated. Coll2-1 peptide, bovine type II collagen (CIA), streptococcal cell wall (SCW) or saline solution were injected into Lewis rats. The Coll2-1 peptide was injected subcutaneously (SC; 20-200μg/100μl/animal) or intra-articularly (IA; 0.5-5μg/50μl/animal) and compared to CIA injected in SC (200μg/100μl/animal) and SCW in IA (5μg/50μl/animal). The animals were injected on day 0 and monitored for 28 days. Histological lesions assessment was performed using an arthritis score.

RESULTS

Coll2-1 peptide significantly increased IL-8 gene expression and production by synoviocytes. AS0619 and CLI-095 significantly decreased IL-8 expression. Coll2-1 induced p65 and IκBα phosphorylation and oxidative stress inhibitors decreased it. In human chondrocytes culture, Coll2-1 significantly increased MMP-3 and VEGF gene expression. In Lewis rats, CIA, SCW or Coll2-1 injection triggered arthritis. Like CIA or SCW, Coll2-1 induced synovitis, loss of cartilage proteoglycans, cartilage structure lesion and subchondral bone remodeling.

CONCLUSIONS

Coll2-1 activates synoviocytes to produce IL-8 and induces arthritis in rat. These findings suggest that neutralizing Coll2-1 could be a therapeutic approach of arthritis.

Absence of recognition of low alkaline phosphatase level in a tertiary care hospital

SUMMARY

Low serum total alkaline phosphatase level (ALP), the hallmark for hypophosphatasia (HPP), must be recognized to provide appropriate care of the patients and to avoid antiresorptive treatment. The prevalence of persistent low ALP in a clinical setting is 0.13% and the recognition is very low (3%).

INTRODUCTION

A low serum total alkaline phosphatase level is the hallmark for the diagnosis of hypophosphatasia. Although very rare, HPP must be recognized to provide appropriate treatment of non-union fractures and to avoid potentially harmful drugs, such as antiresorptive treatments. The aim of this study was to assess the recognition of persistent low ALP in a tertiary care hospital.

METHODS

Between the 1st of January and the 31st of December 2013, 48,755 patients had ALP assessment in the Biochemistry Department of our hospital. Sixty-eight patients had all serum ALP values persistently below 40 IU/l. Among them, six had potential causes of secondary hypophosphatasia. We consulted the summary discharges of the 62 patients in order to check for the notation of low ALP. Patients from the departments of rheumatology and internal medicine were contacted to fulfill a questionnaire about clinical manifestations potentially related to HPP.

RESULTS

0.13% of hospitalized patients had persistently low value. They were 46.5 ± 17.7 years old, and 73% were females. The low ALP value was notified in the discharge summary for two patients (3%), without any comment. Twenty-four patients (46 + /-16 years old) were contacted. Eight patients had fractures; two had a diagnosis of rickets in the childhood; two had symptomatic chondrocalcinosis. Nine had dental abnormalities. Three were receiving a bisphosphonate; two of them had a fracture while being treated with bisphosphonate.

CONCLUSION

Our study shows that low ALP is not recognized in a clinical setting in adults hospitalized in a tertiary care hospital.

Inter-relations between osteoarthritis and metabolic syndrome: A common link?

Osteoarthritis (OA) is a degenerative disorder of the joint, principally occurring during aging, and characterized by a focal degradation of cartilage. It is the most prevalent rheumatic disease in industrialized countries and represents the second cause of disability in France. However, the etiology of OA remains unclear. There is only one cell type found in cartilage, chondrocyte, which is responsible for its repair and the synthesis of the elements of the extra-cellular matrix. A dysfunction of these cells results in an imbalance between repair and degradation in cartilage, leading to its destruction. Recently, a link between OA and metabolic syndrome (MetS) has been suggested, introducing a notion of metabolic OA, and a new vision of the disease. MetS is characterized by a cluster of factors (insulin resistance, hypertension, dyslipidemia, visceral obesity), although there is still no clear definition of it. During the 20th century, MetS dramatically increased with changes in population lifestyle, becoming a major health issue in industrialized countries. MetS concerns 10-30% of the worldwide population, but is prevalent in 59% of OA patients. Patients with both OA and MetS have more severe symptoms, occurring sooner than in the general population. Indeed, OA is generally a disease concerning the population over 65 years old, but with an associated MetS the target population is around 50 years old. In this review, we will focus on common factors in OA and MetS, such as hypertension, obesity, dyslipidemia, mitochondrial dysfunction and hyperglycemia, linking one disease to the other.

Individual site-specific bone mineral density gain in normocalcemic primary hyperparathyroidism

In this study, we show that successful parathyroidectomy is followed at 1 year by a significant individual bone mineral density (BMD) gain in nearly half of normocalcemic PHPT patients with reduced bone mass. Alkaline phosphatase levels above median were identified as an independent predictor of individual BMD gain in normocalcemic PHPT patients.

INTRODUCTION

The aims of this study were to assess bone mineral density (BMD) gains after parathyroidectomy (PTX) in normocalcemic primary hyperparathyroidism (PHPT) at the individual level and to identify predictors of BMD gain after PTX in this context.

METHODS

Longitudinal cohort study of 55 PHPT patients referred for low bone mass and mild abnormalities of calcium/phosphorus metabolism, and successfully treated by PTX. BMD gain at 1 year was considered significant if ≥0.030 g/cm(2) at one site or more, without any equivalent BMD loss at another site. A logistic regression analysis was performed to identify predictive factors of individual BMD gain.

RESULTS

Among the 55 PHPT patients included, 29 patients with hypercalcemia, 36 patients with normocalcemic PHPT, defined by normal pre-PTX serum total (albumin-corrected) calcium (tCa), including 15 patients with normal ionized calcium (iCa), were identified. At 1 year of PTX, an individual BMD gain was observed in 73.7 % of hypercalcemic, 44.4 % of normocalcemic, and 46 % of PHPT patients with both normal tCa and iCa. Site-specific BMD gains were most important at the spine and hip in all subgroups including patients with normal iCa. Alkaline phosphatase activity above median, which reflects high bone turnover, was predictive of individual BMD gain, both in the overall cohort (OR = 4.9, 95 % CI 1.3-18.9), and in the normocalcemic group: OR = 8.4, 95 % CI 1.4-56.6.

CONCLUSIONS

Successful PTX is followed at 1 year by a significant individual BMD gain in nearly half of normocalcemic PHPT patients with osteoporosis. ALP levels above median could contribute to the therapeutic decision in this context.

APRI and FIB-4 Scores Are Useful After Liver Transplantation Independently of Etiology

Noninvasive liver fibrosis scores are evaluated in hepatitis C virus-infected patients but are less known in liver transplant recipients. Fibrosis is a frequent, multifactorial event in these patients. This preliminary retrospective study reviewed the diagnostic performance of 3 simple scores for liver fibrosis in transplant patients: namely, APRI (aspartate aminotransferase to platelet ratio index), FORNS (platelets, gamma-glutamyltransferase, patient age, and cholesterol), and FIB-4 (patient age, aspartate aminotransferase, alanine aminotransferase, and platelets). Ninety-four biopsies were collected from 50 liver transplant recipients at a mean period after orthotopic liver transplantation (OLT) of 30.7 months (range, 12-108 months). The indications for OLT were hepatitis C in 23% of cases, hepatitis B in 14%, alcoholic disease in 33%, cholestatic disease in 19%, and others in 11%. According to the Metavir classification, 72% of biopsies revealed no significant histological fibrosis (F0-1 = group 1) and 28% showed significant fibrosis (F2-4 = group 2). A correlation was observed between the histological stage of fibrosis and albumin, gamma-glutamyltransferase, aspartate aminotransferase, alanine aminotransferase, and hyaluronic acid levels. APRI and FIB-4 correlated significantly with the histological stage of fibrosis both globally and in the subgroup of nonhepatitis C liver recipients. When APRI and FIB-4 tests were applied to predict fibrosis (area under the receiver operating characteristic curve), the results were 0.87 and 0.78, respectively. Values were not significant with the FORNS test. In conclusion, APRI and FIB-4 enabled accurate prediction of significant fibrosis after OLT. In the nonhepatitis C subgroup, we found similar predictive performances. These simple scores may be applied in clinical practice in the context of follow-up after OLT independent of hepatitis C status.

N-terminal pro-brain natriuretic peptide in systemic sclerosis: a new cornerstone of cardiovascular assessment?

BACKGROUND

Cardiac involvement, a common and often fatal complication of systemic sclerosis (SSc), is currently detected by standard echocardiography enhanced by tissue Doppler echocardiography (TDE).

OBJECTIVE

The performance of the biomarker of cardiovascular disease, N-terminal pro-brain natriuretic peptide (NT-proBNP), in the detection of cardiac involvement by SSc was examined.

METHODS

A total of 69 consecutive patients with SSc (mean (SD) age 56 (13) years, 56 women) were prospectively studied with standard echocardiography and TDE measurements of longitudinal mitral and tricuspid annular velocities. Plasma NT-proBNP was measured in all patients.

RESULTS

Overall, 18 patients had manifestations of cardiac involvement, of whom 7 had depressed left ventricular and 8 depressed right ventricular myocardial contractility, and 8 had elevated systolic pulmonary arterial pressure. Patients with reduced contractility had increased mean (SD) NT-proBNP (704 (878) pg/ml versus 118 (112) pg/ml in patients with normal myocardial contractility, p<0.001). Similarly, NT-proBNP was higher in patients with (607 (758) pg/ml) than in patients without (96 (78) pg/ml) manifestations of overall cardiac involvement (p<0.001). Receiver operating characteristic analysis showed NT-proBNP reliably detected depressed myocardial contractility and overall cardiac involvement (area under the curve 0.905 (95% CI 0.814 to 0.996) and 0.935 (95% CI 0.871 to 0.996), respectively). Considering patients with SSc with normal echocardiography and TDE as controls, and using a 125 pg/ml cut-off concentration, sensitivity and specificity were 92% and 71% in the detection of depressed myocardial contractility, and 94% and 78% for overall cardiac involvement.

CONCLUSIONS

NT-proBNP reliably detected the presence of cardiac involvement and appears to be a very useful marker to risk stratify patients presenting with SSc.

Disturbed angiogenesis in systemic sclerosis: high levels of soluble endoglin

OBJECTIVE

SSc is a CTD characterized by early generalized microangiopathy with disturbed angiogenesis. Soluble endoglin (sENG), a serum anti-angiogenic protein, has recently been described as a major actor in pre-eclampsia, another severe vascular disease with abnormal angiogenesis. The aim of this study was to investigate, in a cross-sectional study, sENG levels together with other serum vascular markers.

METHODS

Serum levels of sENG were assessed by ELISA in consecutive SSc patients and controls matched for age and sex. We also measured by ELISA serum levels of VEGF and asymmetric dimethylarginine (ADMA), as respective markers of angiogenesis and endothelial dysfunction.

RESULTS

We included 235 unrelated subjects: 187 SSc patients and 48 controls. Higher concentrations of sENG (P = 0.002) and sVEGF (P < 0.0001) were found in SSc patients compared with controls whereas there was no difference for ADMA. In multivariate analysis, sENG levels were significantly increased in SSc patients with cutaneous ulcerations (P = 0.0003), positive for ACAs (P = 0.009) and with abnormal diffusing capacity for carbon monoxide divided by alveolar volume (P = 0.03). Soluble ENG levels negatively correlated with ADMA, but no relationship was found between sENG and sVEGF.

CONCLUSION

This study shows increased values of sENG in a large SSc cohort and a relevant association with a vascular phenotype. The predictive value of the biomarker sENG and its potential role on cellular endothelial disturbances remain to be determined.

High N-terminal pro-brain natriuretic peptide levels and low diffusing capacity for carbon monoxide as independent predictors of the occurrence of precapillary pulmonary arterial hypertension in patients with systemic sclerosis

OBJECTIVE

To evaluate predictors of pulmonary arterial hypertension (PAH) in a prospective cohort of patients with systemic sclerosis (SSc).

METHODS

Routine clinical assessments as well as measurements of the diffusing capacity for carbon monoxide/alveolar volume (DLCO/VA) ratio and N-terminal pro-brain natriuretic peptide (NT-proBNP) level were performed in a prospective cohort of 101 SSc patients who did not have PAH or severe comorbidities. After a planned 36-month followup, we evaluated the predictive value of these parameters for the development of precapillary PAH, as demonstrated by cardiac catheterization, disease progression, and death. Criteria for cardiac catheterization were a systolic pulmonary artery pressure (PAP) of >40 mm Hg on echocardiography, a DLCO value of <50% without pulmonary fibrosis, and unexplained dyspnea.

RESULTS

Eight patients developed PAH, 29 had disease progression, and 10 died during a median followup of 29 months. Kaplan-Meier analysis identified the following baseline parameters as being predictors of PAH: DLCO/VA ratio <70% or <60% (P<0.01 for each comparison), elevated plasma NT-proBNP level (>97th percentile of normal; P = 0.005), echocardiographically estimated systolic PAP >40 mm Hg (P=0.08), and erythrocyte sedimentation rate >28 mm/hour (P=0.015). In multivariate analyses, an elevated baseline NT-proBNP level (hazard ratio [HR] 9.97 [95% confidence interval (95% CI) 1.69-62.42]) and a DLCO/VA ratio <60% (HR 36.66 [95% CI 3.45-387.6]) were predictors of the occurrence of PAH during followup. An increased NT-proBNP level together with a decreased DLCO/VA ratio of <70% was highly predictive of the occurrence of PAH during followup (HR 47.20 [95% CI 4.90-450.33]).

CONCLUSION

This prospective study identified a decreased DLCO/VA ratio and an increased NT-proBNP as predictors of PAH in SSc. Use of these markers should result in improved PAH risk stratification and allow earlier initiation of therapy.

Superoxide production and NADPH oxidase expression in human rheumatoid synovial cells: regulation by interleukin-1beta and tumour necrosis factor-alpha

OBJECTIVES

to evaluate the rheumatoid synovial cell capacity to produce superoxide anion in response to interleukin-1beta (IL-1beta) and tumour necrosis factor-alpha (TNF-alpha), and to study the NADPH oxidase involvement in this production.

MATERIAL AND METHODS

Synovial cells obtained from 7 rheumatoid arthritis (RA), 5 osteoarthritic (OA) patients, and dermal fibroblasts, were stimulated (i) with IL-1beta and TNF-alpha, or (ii) with specific oxidase activators and inhibitors, before studying superoxide production; we also studied NADPH oxidase mRNAs and protein expression, and p47-phox phosphorylation.

RESULTS

Constitutive superoxide production by RA cells was increased in comparison to OA cells and dermal fibroblasts, and was stimulated by PMA and ionomycin. This production was increased after cytokine treatment of RA synovial cells. Cytokine-induced superoxide production by RA cells was inhibited by iodonium diphenyl or apocynin, suggesting the involvement of NADPH oxidase. RT-PCR and western blot analysis revealed the presence of p47-phox, gp91-phox and Nox4 in RA and OA cells, and in dermal fibroblasts. P47-phox phosphorylation was enhanced after cytokine-treatment in RA and OA cells, suggesting a PKC-mediated up-regulation of NADPH oxidase.

CONCLUSIONS

NADPH oxidase is involved in the superoxide release by RA synovial cells, constitutively and after cytokine up-regulation. These cells express two different homologues (gp91-phox and Nox4).

Serum protein oxidation in patients with rheumatoid arthritis and effects of infliximab therapy

OBJECTIVE

To examine protein oxidation in rheumatoid arthritis (RA) and evaluate its evolution after infliximab therapy in a subgroup of patients.

METHODS

Seventy-one consecutive patients with RA were included. Among them, 30 patients refractory to conventional therapy were treated with infliximab. Serum markers of oxidative stress were determined at baseline and before the infusions of infliximab at weeks 6 and 30. Baseline values were compared with those in 30 healthy volunteers.

RESULTS

Mean levels of serum carbonyl groups were significantly higher in RA patients than in controls (1.29+/-0.76 versus 0.58+/-0.39 nmol/mg of protein, p<0.0001), whereas thiol levels were found to be lower (238.3+/-61.6 versus 316.5+/-54.8 micromol/L, p<0.0001). Thiol levels inversely correlated with the disease activity score (r=-0.42, p=0.004), and with CRP values (r=-0.45, p=0.001). Immunoblots showed that albumin and heavy chain immunoglobulin were oxidized more markedly than in healthy volunteers. Significantly lower levels of thiol groups were detected in patients with refractory RA disease (208.9+/-66.8 versus 264.2+/-43.0 micromol/L, p<0.0004) but concentrations of carbonyl groups were similar. Short-term treatment with infliximab significantly decreased carbonyl groups (0.97+/-0.47 nmol/mg protein, p=0.02) and increased thiol (231.2+/-48.7 micromol/L, p=0.02) levels.

CONCLUSION

Our results highlight free radical protein damage in RA and a link with inflammation, as underlined by the beneficial effects of infliximab.

Lack of association between three vascular endothelial growth factor gene polymorphisms and systemic sclerosis: results from a multicenter EUSTAR study of European Caucasian patients

INTRODUCTION

Systemic sclerosis (SSc) is characterised by disturbed vessel morphology and an overproduction of vascular endothelial growth factor (VEGF). The VEGF gene located on chromosome 6p21.3 has several polymorphisms.

OBJECTIVE

To test the hypothesis that disturbed angiogenesis may be related to the genetic background of the VEGF gene.

MATERIALS AND METHODS

EUSTAR centres included European Caucasian patients with SSc and matched controls with osteoarthritis. The VEGF gene was genotyped by polymerase chain reaction, followed by restriction enzyme analysis. The 634 C/T and 936 C/G mutations and an 18-base pair insertion/deletion at -2549 of the VEGF promoter region were tested.

RESULTS

416 patients with SSc and 249 controls were included in the study population. Of the patients with SSc, 42% had a diffuse cutaneous subtype, 16% had increased pulmonary arterial pressure and 61% had decreased carbon monoxide diffusion capacity. The genotype frequencies in the patients with SSc and in controls were in Hardy-Weinberg equilibrium. The allele and genotype frequencies of the polymorphisms did not differ between patients with SSc and controls. No association was found between these polymorphisms and disease phenotypes.

CONCLUSION

This study shows that there is no association between the three selected functional VEGF polymorphisms and SSc.

Increased plasma soluble CD40 ligand concentrations in systemic sclerosis and association with pulmonary arterial hypertension and digital ulcers

BACKGROUND

Increased expression of CD40L has been reported on activated CD4+ T lymphocytes in systemic sclerosis. CD40L can be expressed in soluble form (sCD40L).

OBJECTIVE

To compare sCD40L concentrations in patients with systemic sclerosis and healthy controls.

METHODS

Quantitative sandwich ELISA was used to measure plasma sCD40L in systemic sclerosis (n = 50) and matched healthy controls (n = 20). Patients with systemic sclerosis had limited cutaneous disease (29), digital ulcers (14), pulmonary arterial hypertension (PAH) (10), pulmonary fibrosis on CT (23), positive anti-Scl70 (14), and anti-centromere antibodies (10). Calcium channel blockers were discontinued 72 hours before measurements.

RESULTS

Median (range) sCD40L concentration (pg/ml) was higher in systemic sclerosis than in controls (495 (10 to 7720) v 79 (50 to 118); p = 0.003), in limited cutaneous disease v diffuse disease (620 (20 to 7720) v 250 (10 to 2690); p = 0.005), in patients with digital ulcers v those without (1430 (36 to 7720) v 370 (10 to 2320); p = 0.002), and in those with PAH v those without (995 (15 to 3850) v 400 (10 to 7720); p = 0.048). sCD40L correlated with pulmonary arterial pressure estimated by Doppler echocardiography (r = 0.41; p = 0.005).

CONCLUSIONS

The soluble form of CD40L is increased in plasma in systemic sclerosis and may be associated with vascular complications of the disease.

N-terminal pro-brain natriuretic peptide as a diagnostic marker of early pulmonary artery hypertension in patients with systemic sclerosis and effects of calcium-channel blockers

OBJECTIVE

To evaluate N-terminal pro-brain natriuretic peptide (NT-proBNP) as a marker of early pulmonary artery hypertension (PAH) and to study changes in the levels of this marker following treatment with dihydropyridine-type calcium-channel blocker (DTCCB) in patients with systemic sclerosis (SSc).

METHODS

We evaluated 40 consecutive SSc patients who had been hospitalized for followup care (mean +/- SD age 56 +/- 11 years and mean +/- SD duration of cutaneous disease 9 +/- 9 years; 27 with limited cutaneous and 13 with diffuse cutaneous disease) but who had no clinical symptoms of heart failure and had a normal left ventricular ejection fraction. At baseline, 10 patients had PAH, defined as a systolic pulmonary artery pressure (sPAP) >40 mm Hg, as measured by echocardiography. Levels of NT-proBNP were determined at baseline (after discontinuation of DTCCB treatment for 72 hours), after taking 3 doses of DTCCB following treatment reinitiation (assessment 1), and after 6-9 months of continuous DTCCB treatment (assessment 2) in the 20 patients who attended regular appointments (including the 10 patients with PAH at baseline).

RESULTS

At baseline, 13 patients had high NT-proBNP values for their ages. High NT-proBNP levels identified patients with PAH with a sensitivity of 90%, a specificity of 90.3%, a positive predictive value of 69.2%, and a negative predictive value of 96%. The NT-proBNP level correlated with the sPAP (r = 0.44; P = 0.006). By assessment 1, the number of patients with PAH and high levels of NT-proBNP had decreased from 9 of 10 to 2 of 10 (P = 0.02). This decrease was partially sustained at assessment 2 (4 of 10 patients; P = 0.06).

CONCLUSION

NT-proBNP is a useful biologic marker that can be used to diagnose early PAH in SSc patients without clinical heart failure. Measurement of NT-proBNP may be valuable for the evaluation of treatment with DTCCB and vasodilators in patients with PAH.

Effects of bile acids on the humoral immune response: a mechanistic approach

Whereas bile acids in excess depress the cell-mediated immune response, their effects on the humoral response have been little investigated. The aim of this study was to investigate the effects of bile acids on immunoglobulin production. Human peripheral blood mononuclear cells were stimulated for 5 days by Staphylococcus aureus Cowan I (SAC-I). Immunoglobulins were measured in the supernatants and cell lysates using ELISA. We found that bile acids inhibited IgM production in a dose-dependent manner. The inhibitory effects of 50 microM chenodeoxycholic acid (CDCA) and its glyco- and tauro-conjugates (62, 53 and 51%, respectively) were stronger than those of ursodeoxycholic acid (UDCA) and its conjugates (45, 40 and 34%, respectively). The inhibition of IgG production by CDCA and UDCA was weak (23 and 12%, respectively, at 50 microM). IgA production was not modified. The inhibition of intracellular IgM concentration paralleled that observed in the secreted compartment. By contrast, CDCA enhanced intracellular concentration of IgG. In the absence of significant necrosis or apoptosis, CDCA-mediated inhibition of SAC-I-induced IgM production was significantly correlated to the ability of the bile acid to inhibit cell proliferation (r=0.98; p<0.05). In conclusion, we showed that hydrophobic bile acids strongly depress the primary humoral response. This effect resulted from both an inhibition of cell proliferation, and to a lesser extent from a deficient exocytosis of immunoglobulins.

Variability in urinary excretion of bone resorption markers: limitations of a single determination in clinical practice

In this study we assessed the within and between-subject variability of the concentrations of two urinary markers, free deoxypyridinoline (DPD) and C telopeptide (CTX-I), in healthy patients with the aim of setting reliable thresholds to enable physicians to take decisions about individual patients with confidence.Between-subject variability for the women was 25.4% for DPD and 38.2% for CTX-I, and for the men was 12.9% for DPD and 23.8% for CTX-I. The coefficients of variation were similar for daily, weekly and monthly determinations, giving means of 13.8 and 28.1% for DPD and CTX-I respectively. Critical difference (CD) was lower for DPD than for CTX-I (about 44 and 80% respectively). The number of samples required to determine the true mean with a CD at the 5% level was 29 for DPD and more than 113 for CTX-I.DPD was the least biologically variable. One determination was not sufficient to determine bone resorption status and a 44% decrease in DPD levels and an 80% decrease in CTX-I levels were required to demonstrate the efficacy of antiresorptive therapy in individual patients.

Low levels of nitric oxide (NO) in systemic sclerosis: inducible NO synthase production is decreased in cultured peripheral blood monocyte/macrophage cells

OBJECTIVE

To investigate nitric oxide (NO) production and inducible NO synthase expression by cultured peripheral blood mononuclear cells (PBMC) in patients with systemic sclerosis (SSc).

METHODS

Eighteen patients with SSc were compared with two control groups: 16 patients with rheumatoid arthritis (RA) and 23 patients with mechanical sciatica. Nitrate was determined by fluorimetry in plasma and by spectrophotometry in supernatants. Inducible NO synthase (iNOS) was detected in cultured PBMC by immunofluorescence, immunoblotting and flow cytometry with or without treatment of the cells with interleukin (IL) 1beta+ tumour necrosis factor alpha (TNF-alpha), IL-4 or interferon gamma (IFN-gamma) from day 1 to day 5.

RESULTS

NO metabolite concentrations were lower in SSc patients (mean+/-s.e.m. 34.3+/-2.63 micromol/l) than in RA (48.3+/-2.82 micromol/l; P<0.02) and sciatica (43.3+/-5.24 micromol/l; P<0.03) patients. iNOS was detected in cultured monocytes in all three groups but induction occurred on day 1 in RA, day 2 in sciatica and only on day 3 in SSc, whatever the stimulus.

CONCLUSIONS

The concentrations of NO metabolites are decreased in SSc patients and the metabolism of these compounds in PBMC is altered. Low levels of NO, a vasodilator, may be involved in vasospasm, which is critical in SSc. This may have therapeutic implications.

[Inducible nitric oxide synthase expression and nitric oxide production by monocytes in systemic sclerosis]

We investigated nitric oxide (NO) production and inducible NO synthase (iNOS) expression by cultured peripheral blood mononuclear cells (PBMC) in systemic sclerosis (SSc). Eighteen patients with SSc were compared to two control groups: 16 rheumatoid arthritis patients (RA) and 23 mechanical sciatica patients. The sum of nitrites and nitrates was determined by fluorimetry in sera and spectrophotometry in supernatants. Inducible iNOS was detected in cultured PBMC by immunofluorescence, immunoblot and flow cytometry with or without IL-1 beta + TNF alpha, IL-4 or IFN gamma from day 1 to day 5. NO metabolite concentrations in the plasma were lower in SSc (34.3 mumol/l +/- 2.63 SEM) than in RA (48.3 mumol/l +/- 2.2; p < 0.02) and sciatica (43.3 mumol/l +/- 5.24; p < 0.03) patients. iNOS was detected in cultured monocytes in the 3 groups but induction occurred on day 1 in RA, day 2 in sciatica and only on day 3 in SSc, whatever the stimulus. The concentrations of NO metabolites are decreased in SSc patients and the induction of iNOS in PBMC is delayed. Low levels of NO, a vasodilator, may be involved in vasospasm, which is critical in SSc. This may suggest therapeutic implications.

Tetracyclines inhibit nitrosothiol production by cytokine-stimulated osteoarthritic synovial cells

OBJECTIVE AND DESIGN

To evaluate the capacity of doxycycline and minocycline to inhibit NO production and N-nitrosation reactions in vitro.

METHODS

Synovial cells obtained from 6 patients with osteoarthritic joint disease were incubated for 24 hours with (i) or without (ii) IL-1beta (1 ng/ml), TNF-alpha (500 pg/ml), IFN-gamma (10(4) U/ml) plus minocycline or doxycycline (10(-4) to 10(-6) M), diclofenac (10(-5) M), or cortisol (10(-5) M). Nitrosothiols were determined by fluorimetry, nitrite by the Griess reaction, nitrate by a spectrophotometric assay using oxidation by nitrate reductase and iNOS by immunoblotting.

RESULTS

After 24 hours of stimulation, the level of NO production was much higher than that in untreated cells: about 5.5 times higher for nitrosothiols, 5.2 times higher for nitrate and about 3.5 times higher for nitrite. Doxycycline and minocycline induced a dose-dependent decrease in the production of nitrosothiols, nitrate and nitrite, and inhibited the synthesis of the iNOS protein. Doxycycline and minocycline inhibited the N-nitrosation reaction of DAN effectively, with IC50 values close to 100 microM. Diclofenac and cortisol had no effect.

CONCLUSION

This study provides new information on the mechanism by which tetracyclines exert anti-inflammatory effects, via inhibiting nitrosothiols.

Systemic inflammatory response with plasma C-reactive protein elevation in disk-related lumbosciatic syndrome

OBJECTIVE

To look for a systemic inflammatory response in patients with disk-related lumbosciatic syndrome by using an ultrasensitive (US) plasma C-reactive protein (CRP) assay, and to determine whether plasma CRP-US levels correlated with clinical and/or laboratory features.

PATIENTS AND METHODS

Plasma CRP was assayed using an enzyme-linked immunosorbent assay (ELISA) (detection limit, 5 microg/L) in patients with sciatica shown by computed tomography to be due to a disk herniation. Levels in 35 patients aged 23 to 64 years were compared to those in age- and sex-matched controls.

RESULTS

Mean CRP-US levels measured by ELISA were significantly higher in the patients than in the controls (1.68 vs 0.74 mg/L; P = 0.002). There was a trend toward higher CRP-US levels in the patients with more severe nerve root symptoms.

CONCLUSION

The significantly higher plasma CRP-US levels by ELISA in our patients with disk-related lumbosciatic syndrome is consistent with a systemic inflammatory response to the local nerve root impingement.

Inhibition of the nitrosothiol production of cultured osteoarthritic chondrocytes by rhein, cortisol and diclofenac

OBJECTIVE

Nitric oxide (NO degrees ) is a free molecule produced by NO synthases which acts as a mediator in inflammatory processes. NO degrees can react with thiol groups of proteins to produce nitrosothiols. Increased concentrations of these bioactive compounds have been found in sera and synovial fluids from patients with osteoarthritis (OA). The aim of this study was to assess the ability of human osteoarthritic chondrocytes to synthesize nitrosothiols and to compare the in vitro effects of rhein, cortisol and diclofenac on nitrosothiol and nitrite production.

METHODS

Osteoarthritic chondrocytes were incubated for 24 h with 1 ng/ml of recombinant human interleukin-1beta (IL-1beta) in the presence or absence of rhein (1.3x10(-5) M, 6.5x10(-6) M, or 1.3x10(-6) M), cortisol (10(-5) M) or diclofenac (10(-5) M or 10(-6) M). Nitrite levels were measured in cell supernatants by the Griess method; nitrosothiol levels were determined in supernatants and cellular lysates by fluorimetry.

RESULTS

At the basal level, nitrosothiols represented 80% of the total of nitrite and nitrosothiol production. After IL-1beta stimulation, NO degrees production was highly increased in the supernatants (45-fold increase in nitrite, 60-fold increase in nitrosothiols) as well as in cell lysates (35-fold increase in nitrosothiols). Rhein caused a dose-dependent decrease in nitrosothiol and nitrite production. In comparison, diclofenac (10(-5) M) moderately decreased nitrite and nitrosothiol levels in the supernatants but had no effect on lysate nitrosothiol. Cortisol had no significant effect on NO degrees production.

CONCLUSIONS

The IL-1beta stimulation increased nitrosothiol production by osteoarthritic chondrocytes. These results demonstrate the need to measure nitrosothiol as well as nitrite production. Rhein inhibited the IL-1beta induced NO degrees production, and may be a suitable treatment for osteoarthritis.

Nitric oxide modifies glycolytic pathways in cultured human synoviocytes

Nitric oxide (NO) is a free radical produced during inflammation following activation of an inducible NO synthase by pro-inflammatory cytokines such as IL-1beta. Since both NO and IL-1beta are involved in the physiopathology of inflammatory arthropathies, we investigated the effects of exogenous NO on glycolytic pathways in cultured human osteoarthritic synovial cells. NO generated from S-nitroso-N-acetyl penicillamine (SNAP) or sodium nitroprusside (SNP) inhibited glucose uptake (by 50% after 1 h of incubation) and lactate production by 16% (SNAP) and 8.5% (SNP) after 3 h. Both NO donors also reduced production of glyceraldehyde-3-phosphate dehydrogenase (GAPDH), an enzyme of the glycolytic pathway. This effect was reversed by haemoglobin, a NO scavenger with higher affinity for the radical. In contrast, the effect on glucose uptake appeared to be irreversible.

Reactive oxygen species induce apoptosis of synoviocytes in vitro. Alpha-tocopherol provides no protection

Reactive oxygen species (ROS) are released during the inflammation of the synovial membrane associated with cartilage degradation in osteoarthritis. In this work, we exposed synoviocytes to superoxide anions at concentrations that may cause either apoptosis or necrosis. We studied membrane organization, dehydrogenase mitochondrial activity and nuclear morphology and integrity, to determine the nature of the death process initiated by superoxide anions and tried to counteract ROS effects with alpha-tocopherol. We found that oxidative stress caused synoviocytes to undergo a process of cell death of an apoptotic nature rather than necrotic. Mitochondrial injury occurred at an early stage, and the FITC-annexin-V-positive/propidium iodide-positive cells occurred later than the metabolic changes. DNA strand breaks were evident at 8 h and nuclear condensation at 24 h. No LDH activity was detected in culture supernatants. In our experimental conditions, alpha-tocopherol had little effect on stress damage; the antioxidant properties of this molecule did not affect the apoptosis caused by superoxide anions.

Nitric oxide synthase is expressed in the lymphomononuclear cells of synovial fluid in patients with rheumatoid arthritis

OBJECTIVE

To investigate the expression of inducible nitric oxide synthase (iNOS) in subpopulations of peripheral blood and synovial fluid (SF) leukocytes in patients with rheumatoid arthritis (RA).

METHODS

iNOS was detected in peripheral blood and SF samples after cell permeabilization, by 2 color immunofluorescence flow cytometry. Samples from 14 patients with RA and 8 with osteoarthritis (OA) were studied. Nitrite concentration was determined by Griess reaction, interleukin 1beta and tumor necrosis factor alpha by an immunoenzymatic assay, and C-reactive protein (CRP) by an immunonephelometric method.

RESULTS

In SF, iNOS was detected in 11 of 14 patients with RA and 2 of 8 with OA. In blood cells, iNOS was detected in 8 of 14 patients with RA and none of the OA group. iNOS was consistently detected in monocytes and was not detected in granular cells. In RA, there was no correlation between the number of iNOS positive mononuclear cells and cytokine concentrations. CRP concentration was correlated with the number of iNOS positive mononuclear cells in RA SF samples.

CONCLUSION

SF mononuclear cells from patients with RA express iNOS and are involved in NO production in the joint. The number of positive cells is correlated with CRP concentration, suggesting the implication of NO production in the inflammatory process.

Osteoporosis, body composition, and bone turnover in ankylosing spondylitis

OBJECTIVE

To study the prevalence of osteoporosis (OP) and osteopenia in ankylosing spondylitis (AS) and to investigate the relationship between symptomatic and structural severity, the indices of bone turnover, and body composition.

METHODS

Eighty patients with AS were enrolled prospectively: 52 men (65%) and 28 women, mean age 36.7 years +/- 11.5 (range 18-67); they were studied clinically, radiologically, and by dual energy x-ray absorptiometry. Sixty-three underwent biological assessment of bone turnover markers.

RESULTS

OP and osteopenia as defined by the World Health Organization (T score < -2.5 SD and between -1 and -2.5 SD, respectively) were observed in 15 (18.7%) and 25 patients (31.2%) at the lumbar spine and in 11 (13.7%) and 33 patients (41.2%) at the femoral neck, respectively. Patients with OP had a lower body mass index (BMI) and fat mass percentage. There was a trend to a lower disease duration in patients with OP at the spine than in healthy subjects. Bone resorption markers (urinary D-pyridinoline or C-telopeptide concentrations) were increased in 34 patients (53.9%). Bone turnover markers were positively correlated with C-reactive protein concentration and Larsen radiological hip score; they were negatively correlated with Schober index and fat mass percentage.

CONCLUSION

(1) OP is frequent in AS and can be observed in early stages of the disease. (2) Patients with AS are more susceptible to develop OP when they have low BMI, low fat mass percentage, and active and severe disease. OP was observed in parallel with increased bone resorption.

[Inhibition by rhein of nitrosothiol production of human chondrocytes from osteoarthritis in culture]

Nitric oxide (NOo) is an inorganic radical produced after the activation of a NO synthase involved in inflammatory and immune reactions. It can react with protein thiols to form nitrosothiols, a bioactive molecule or can generate in nitrite or nitrate. High concentrations of these metabolites have been found in sera and synovial fluids from patients with osteoarthritis, the higher synovial concentrations suggesting NOo intra-articular production. The aim of this study was to evaluate the capacity of osteoarthritic chondrocytes to produce bioactive NOo metabolites and to study the inhibitory effect of rhein, the active form of diacerhein. Chondrocytes were stimulated by interleukin-1 beta (1 ng/ml) during 24 hours in presence or absence of rhein (1.3 x 10-5, 6.5 x 10-6, 1.3 x 10-6 M) or diclofenac (10-5, 10-6 M). After 24 hours, nitrite and nitrosothiols were measured in the supernatants and nitrosothiols were also determined in cell lysats. After interleukin-1 beta stimulation chondrocytes produced great quantities of nitrosothiols and nitrite. This effect was inhibited in a dose dependent manner by rhein but not by diclofenac. In conclusion, chondrocytes produce high quantities of nitrosothiols after IL-1 beta stimulation and this effect is inhibited by rhein. This drug could be beneficial to prevent the destruction of osteoarthritic cartilage.

Homocysteine decreases endothelin-1 production by cultured human endothelial cells

Hyperhomocysteinemia is believed to be responsible for the development of vascular disease via several mechanisms, including the impairment of endothelial-cell functionality. In-vitro studies have demonstrated that homocysteine decreases the production or bioavailability of vasodilator autacoids, such as prostacyclin and NO. Here, we show that the treatment of human endothelial cells with noncytotoxic homocysteine concentrations leads to a dose-dependent decrease in both the secretion of the vasoconstrictor agent endothelin-1 (ET-1) and the level of its mRNA. Homocysteine had an inhibitory effect at pathophysiological (0.1 and 0.5 mmol.L(-1)) and pharmacological noncytotoxic (1.0 and 2.0 mmol.L(-1)) concentrations. Mean percentage variation from control for ET-1 production was -36. 2 +/- 18.9% for 0.5 mmol.L(-1) homocysteine and -41.5 +/- 26.8% for 1.0 mmol.L(-1) homocysteine, after incubation for 8 h. Mean percentage variation from control for steady-state mRNA was -17.3 +/- 7.1% for 0.5 mmol.L(-1) homocysteine and -46.0 +/- 10.1 for 1.0 mmol.L(-1) homocysteine, after an incubation time of 2 h. ET-1 production was also reduced by incubation with various other thiol compounds containing free thiol groups, but not by incubation with thiol compounds with no free thiol group. Co-incubation of cells with homocysteine and the sulfhydryl inhibitor N-ethylmaleimide prevented the effect of homocysteine on ET-1 production, confirming a sulfhydryl-dependent mechanism. Based on the reciprocal feedback mechanism controlling the synthesis of vasoactive mediators, these preliminary data suggest a mechanism by which homocysteine may selectively impair endothelium-dependent vasodilation by primary inhibition of ET-1 production.

Apoptosis induced by nitric oxide is associated with nuclear p53 protein expression in cultured osteoarthritic synoviocytes

OBJECTIVE

Nitric oxide (NO) is a free radical molecule endogenously produced by NO synthases that may play a critical role in inflammation. It inhibits cell proliferation and may be involved in the induction of apoptosis in various cellular models. Recently, the presence of apoptotic cells was reported in the synovium of osteoarthritic (OA) patients. The aim of this study was to determine whether synovial fibroblasts are target cells for NO-induced apoptosis. The expression of p53 protein was also studied to evaluate the ability of synovial cells to repair DNA fragmentation.

METHODS

Synoviocytes from OA patients were treated with two NO donors: sodium nitroprusside (SNP) and S-nitroso-N-acetyl-penicillamine (SNAP). Apoptosis was analysed by transmission electron microscopy. DNA content was evaluated by flow cytometric analysis after propidium iodide staining and recognition of DNA strand break determined by the TUNEL (TdT-mediated dUTP nick end labeling) method. P53 protein expression was studied by immunofluorescence using a monoclonal antibody.

RESULTS

After 6 hours, cells treated with NO donors (1.25 mM) showed a cytoplasmic condensation and vacuolization. DNA strand break analysis by the TUNEL method confirmed the presence of a DNA fragmentation after 24 hours of NO treatment. There was also a progressive decrease in the DNA diploid peak in response to NO donors. In parallel, p53 protein, constitutively expressed in cytoplasmic synovial cells, showed markedly increased expression after a 6-hour NO exposure and displayed prominent nuclear staining after 12 hours.

CONCLUSIONS

This study demonstrates the potential role of NO for the induction of synoviocyte apoptosis in OA. The increased expression of p53 in the nucleus may play a protective role in the control of apoptosis.

Biochemical markers as predictors of bone mineral density changes after GnRH agonist treatment

To evaluate bone biochemical markers as predictors of the efficacy of a hormone replacement therapy (HRT), we studied the bone changes induced by the cessation and return of ovarian function in 28 patients treated for 6 months with a GnRH agonist. This model reproduced the effects observed in postmenopausal women with high bone turnover treated with HRT. At the end of the treatment, Z scores were 1.8 +/- 0.3 for Crosslaps (CTx) and deoxypyridinoline (D-Pyr), and 1.1 +/- 0.2 for bone alkaline phosphatase (B-ALP) and osteocalcin (OC). This indicated an imbalance in bone remodeling with a high bone resorption. Bone mineral density (BMD) fell by 4.2 +/- 2.5%. The changes in BMD between the 6th and 12th months were 0. 34 +/- 2.24 and -1.73 +/- 3.25% at the lumbar spine and the femoral neck, respectively. Biochemical markers except urinary calcium and hydroxyproline measured at 6 months were positively correlated with the BMD changes at the lumbar spine. After the resumption of menstruation, 13 of 28 women displayed positive spine BMD changes between the 6th and 12th months; in this group, bone biochemical markers measured at 6 months were significantly higher (P = 0.02). Stepwise regression analysis showed that the association of B-ALP and D-Pyr measured at 6 months explained 40% of BMD variance and the association of B-ALP, PTH, and estradiol 56%. We conclude that measuring individual biochemical bone markers can help to predict the bone effect of an increase in the circulating estradiol in women with ovarian deficiency.

Nitric oxide as S-nitrosoproteins in rheumatoid arthritis

OBJECTIVE

Nitric oxide (NO) is a free radical involved in inflammation and immune reactions. The presence of NO is usually assessed by assaying its degradation products, nitrite and nitrate. NO binds to thiol-containing proteins to form S-nitrosoproteins (S-NP). The aim of this study was to investigate the presence of S-NP, together with nitrite and nitrate, in patients with rheumatoid arthritis (RA).

METHODS

Forty patients with RA were studied and compared with 24 patients with osteoarthritis (OA) and 21 control subjects. Fourteen patients were treated with 3 consecutive pulses of methylprednisolone for flares of RA. Nitrite was measured by the Griess reaction, and nitrate by a spectrophotometric assay using nitrate reductase. Spectrofluorometry coupled with the inner filter effect was used for the measurement of S-NP.

RESULTS

S-NP was detected in all RA samples, both in serum and synovial fluid (SF). Serum and articular S-NP concentrations were correlated (P < 0.03). In RA, nitrite and S-NP levels were higher in SF than in serum; higher SF levels of the 3 compounds were observed in RA than in OA. S-NP levels in RA patients decreased significantly (P < 0.03) after pulse methylprednisolone treatment, in parallel with the clinical improvement.

CONCLUSION

S-NP, a biologically active form of NO, was consistently present in RA, with higher concentrations within the arthritic joint. S-NP assays should be added to nitrite and nitrate assays for the evaluation of NO metabolism. S-NP could be a stable storage form of active NO in RA, and its measurement could be useful in evaluating pharmacologic interventions that modulate NO generation.

NO-mediated vasodilation in the rat liver. Role of hepatocytes and liver endothelial cells

BACKGROUND/AIMS

Nitric oxide (NO) is a potent vasodilator. We investigated the mechanisms responsible for this effect in the liver.

METHODS

Isolated perfused rat liver and cultures of endothelial sinusoidal cells and hepatocytes were used.

RESULTS

L-arginine (10(-3) M) and NO donor Sin-1 (10(-5) M) respectively increased the liver flow by 52% (p<0.01) and 93% (p<0.01) vs controls. The NO synthase inhibitor Nw-nitro-L-arginine (10(-3) M) and the guanylate cyclase inhibitor methylene blue (10(-5) M) respectively decreased the basal liver flow by 26% and 16% (p<0.05) and inhibited the vasodilating effects of L-arginine. L-arginine (10(-3) M) increased nitrite concentration in hepatocyte culture (77.25+/-7.40 micromol x l(-1) vs 14.70+/-3.55 micromol x l(-1) in controls; p<0.01) and in liver endothelial cell culture (0.36+/-0.09 micromol x l(-1) vs 0.12+/-0.05 micromol x l(-1) in controls; p<0.05). Nw-nitro-L-arginine inhibited the basal production and abolished the L-arginine-induced production of nitrites both in hepatocyte and in liver endothelial cell cultures. The concentration of nitrites in the hepatocyte supernatant rose from 14.70+/-3.55 micromol x l(-1) to 150.50+/-45.55 micromol x l(-1) in the presence of a combination of interleukin-1beta, TNF alpha and interferon gamma.

CONCLUSIONS

Under basal conditions, NO regulates the vascular tone of liver circulation. Both liver endothelial cells and hepatocytes can be implicated. NO production by hepatocytes may increase during inflammation.

Circulating insulin-like growth factor system changes in women with acute estrogen deficiency induced by GnRH agonist

This prospective longitudinal study was undertaken to examine the short-term effects (6 months) of estrogen withdrawal on the circulating IGF system. A series of 40 patients suffering from endometriosis was studied before and after a 6-month treatment period with gonadotrophin releasing hormone (GnRH) agonist and calcium, with or without nasal salmon calcitonin. The plasma concentrations of insulin-like growth factor I (IGF-I) and insulin-like growth factor II (IGF-II) were measured by radioimmunoassay and radioreceptor assay respectively. Plasma IGF binding proteins (IGFBPs) were quantified and characterized by ligand blot and immunoblot. In all patients, a secondary hypoestrogenism was observed, including a 4% decrease in lumbar bone mineral density (L-BMD). The plasma IGF-I and IGF-II concentrations increased after treatment (24%, p < 0.0005 and 40%, p < 0.004 respectively), with no significant difference between the treatment groups. There was a positive correlation between plasma IGF-I (but not IGF-II) changes and changes in urinary deoxypyridinoline (r = 0.32, p < 0.05), urinary C telopeptide of type 1 collagen (r = 0.33, p < 0.04) and total plasma alkaline phosphatases (r = 0.33, p < 0.04). No correlation was found between IGF-I and L-BMD changes, while there was a positive correlation between the changes in plasma IGF-II and L-BMD (r = 0.32, p < 0.05). Ligand blot analysis revealed a significant increase in IGF-II binding to a 29-31 kilodalton region where positive staining with specific antibodies to IGFBP-3 or IGFBP-1 was observed. In conclusion, IGF-I and IGF-II plasma concentrations are both increased following a short period of treatment with a GnRH agonist. The changes in individual IGF peptides are differently correlated with changes in markers of bone remodelling and L-BMD.