Tissue inhibitor of metalloproteinases 1 and 2 directly stimulate the bone-resorbing activity of isolated mature osteoclasts.

Tissue inhibitor metalloproteinases 1 (TIMP-1) and 2 have been reported to inhibit bone resorption. However, here, we report the direct action of both TIMP-1 and TIMP-2 on isolated rabbit mature osteoclasts to stimulate their bone-resorbing activity at significantly lower concentrations (approximately ng/ml) than those (approximately microg/ml) required for the inhibition of bone resorption. The cell population used in this study consisted of a mature osteoclast population with >95% purity. TIMP-1 (approximately 50 ng/ml) and TIMP-2 (approximately 8-10 ng/ml) increased the pit area excavated by the isolated mature osteoclasts. The stimulatory effects of TIMPs were abolished by simultaneous addition of anti-TIMP antibodies. At higher concentrations, the stimulation of bone resorption decreased reversely to the control level. The magnitude of the stimulatory effect of TIMP-2 was more than that of TIMP-1. Metalloproteinase inhibitors such as BE16627B and R94138 could not replace TIMPs with respect to the bone-resorbing activity, suggesting that the osteoclast-stimulating activity of TIMPs was independent of the inhibitory activity on matrix metalloproteinases (MMPs). TIMPs stimulated tyrosine phosphorylation of cellular proteins in the isolated mature osteoclasts. Both herbimycin A, an inhibitor of tyrosine kinases, and PD98059 and U0126, inhibitors of mitogen-activated protein kinase (MAPK), completely blocked the TIMP-induced stimulation of osteoclastic bone-resorbing activity. On the plasma membrane of osteoclasts, some TIMP-2-binding proteins were detected by a cross-linking experiment. These findings show that TIMPs directly stimulate the bone-resorbing activity of isolated mature osteoclasts at their physiological concentrations and that the stimulatory action of TIMPs is likely to be independent of their activities as inhibitors of MMPs.     

Effects ofl-arginine andN-nitro-l-arginine treatment on hemodynamics, DO2, VO2, and extravascular lung water in a dog endotoxin shock model

To verify the effect of nitric oxide pathway modification during sepsis, experiments were conducted in four groups of anesthetized dogs which received lipopolysaccharide (LPS) intravenously (group 1), 300 mg·kg⁻¹ ofl-arginine plus LPS (group 2), 20 mg·kg⁻¹ ofN-nitro-l-arginine plus LPS (l-NNA, group 3), and normal saline as the control group. Hemodynamic and oxygenation data as well as extravascular lung water (EVLW) were measured or calculated. The results showed thatl-arginine increases cardiac output index (CI) and decreased the peripheral vascular resistance index (PVRI) without a significant influence on oxygen extraction ratio (O₂ER), oxygen delivery (DO₂), or oxygen consumption (VO₂). All of the untoward hemodynamic effects of LPS were exacerbated by the addition ofl-NNA. Therefore, as DO₂ was significantlys decreased byl-NNA, and although O₂ER was increased (insufficiently), VO₂ was still decreased significantly. EVLW was markedly increased byl-NNA. These results support the hypothesis that inhibition of nitric oxide synthesis may exacerbate hemodynamic and oxygenation consequences in septic shock.     

Inhibition of parathyroid hormone-stimulated resorption in cultured fetal rat long bones by the main metabolites of ipriflavone

Ipriflavone is an isoflavone derivative used in the prevention and treatment of postmenopausal and senile osteoporosis in humans. To assess the potential contribution of the mainin vivo ipriflavone metabolites (M1, M2, M3, and M5) on the pharmacological properties of the drug, we investigated their effect on osteoclastic resorption induced by the well-known stimulator of bone resorption bovine parathyroid hormone fragment 1–34 (bPTH 1–34). The study was carried out using fetal rat long bones in stationary cultures. The amount of osteoclastic resorption was determined by assaying for 5 days the release from bones in the media of previously incorporated⁴⁵Ca. All metabolites were effective at inhibiting osteoclastic resorption. Maximal potency was shown by M3, characterized by a significant effect at 10 μM (P<0.01) and by an IC₅₀ value of 17 μM. M2 was about threefold less potent than M3 (IC₅₀=46 μM). M1 and m5 were the least active compounds with an IC₅₀ value of 117 and 200 μM, respectively. The present evidence indicates that metabolites of ipriflavone, in particular M3 and M2, inhibit bPTH 1–34-induced bone resorption in fetal rat long bones. Accordingly, they may play an important role in the pharmacological effects of the drug.     

Urinary albumin and TGF β1 levels as renal damage indices in patients with congestive heart failure

Background. In patients with congestive heart failure (CHF), the pathogenic role of angiotensin II in the development of cardiovascular death has widely been accepted. To study the pathophysiological mechanisms of CHF-associated renal damage, we examined urinary albumin levels as a clinical marker of glomerular hyperfiltration and sclerosis, which may be attributed to the upregulated function of angiotensin II. Methods. Twenty outpatients with mild to moderate CHF without renal failure were examined. They were treated with various combinations of angiotensin-converting enzyme inhibitors (ACEI), (n = 9), calcium antagonists (n = 9), β-blockers (n = 6), and diuretics (n = 12). Urinary (u-) levels of albumin, N-acetyl-β-d-glucosaminidase (NAG), and transforming growth factor β-1 (TGF β1), and circulating levels of endothelin-1 (ET-1) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were measured and examined in relation to various clinical parameters and the mode of treatment. Results. (1) CHF patients showed significantly higher mean levels of u-albumin, u-NAG, u-TGF β1, plasma ET-1, and serum TIMP-1 than normal controls. In an age-matched comparison, the u-albumin levels in CHF patients were as high as those in diabetic patients without overt nephropathy and hypertension. (2) The u-albumin level tended to correlate with the u-NAG level (P = 0.051), however, there was no patient with high u-NAG in the subgroup with negative u-albumin levels. (3) The u-albumin level, like the u-TGF β1 and serum TIMP-1 levels, showed a significant positive correlation with the mean arterial pressure (MAP) level (each, P < 0.05), and showed slight, but nonsignificant correlations with the u-TGF β1 (P = 0.08) and serum TIMP-1 levels (P = 0.06). (4) The patients treated with an ACEI showed significantly lower levels of u-albumin (P < 0.01) and serum TIMP-1 (P < 0.05) than those not treated with an ACEI. Treatment with an ACEI tended to decrease positivity for u-TGF β1 (P = 0.09). Conclusions. The correlation between MAP and u-albumin levels and the ameliorative effect of ACEI on u-albumin excretion suggest that urinary albumin excretion may be caused by a glomerular hyperfiltration mechanism produced by both preloading of the systemic blood pressure and afterloading by angiotensin II-mediated constriction of efferent arterioles. In addition, the suppressive effects of ACEI on u-TGF β1 and serum TIMP-1 levels suggest that angiotensin II may accelerate TGF β1-mediated tissue remodeling, including nephrosclerosis, in CHF. Received: February 21, 2001 / Accepted: October 31, 2001     

Serum matrix metalloproteinases MMP-2 and MMP-9 and metalloproteinase tissue inhibitors TIMP-1 and TIMP-2 in diabetic nephropathy

BACKGROUND: The regulation of mesangial extracellular matrix (ECM) turnover engages a number of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs). High glucose concentration affects ECM degradation and the activities of MMPs and TIMPs. ECM accumulation is involved in the pathogenesis of diabetic nephropathy. METHODS: Serum MMP-9, MMP-2, TIMP-2 and TIMP-1 were measured with ELISA in patients with either chronic renal failure (CRF, n=20), type 2 diabetes mellitus (DM2, n=16) or diabetic nephropathy (DM2+CRF, n=14), and healthy controls (n=20). RESULTS: Diabetic nephropathy was related with profound decrease of serum TIMP-2 (122.2 +/- 47.2 vs. 263.0 +/- 89.2 ng/mL), TIMP-1 (242.5 +/- 96.9 vs. 347.4 +/- 87.2 ng/mL) and MMP-2 (385.4 +/- 42.6 vs. 517.2 +/- 75.4 ng/mL) (p<0.001). Both TIMP-1 and TIMP-2 were reduced in diabetic nephropathy in comparison with either diabetes alone (p<0.01 and p<0.001; respectively) or CRF alone (p<0.001 for both). An approximately 2-fold increase of MMP-9/TIMP-1 and MMP-2/TIMP-2 ratio was found in diabetic nephropathy when compared with diabetes with normal renal function (p<0.01). Further, in DM2 patients, TIMP-2 was decreased when compared with CRF alone (219.2 +/- 71.8 vs. 296.8 +/- 58.4 ng/mL). MMP-2 was lowered in both groups of DM2 and CRF patients (413.8 +/- 59.0 ng/mL and 409.7 +/- 93.1 ng/mL, vs. normal control value of 517.2 +/- 75.4 ng/mL; p<0.001). CONCLUSIONS: These data indicate that circulating TIMP-1, TIMP-2 and MMP-2 are decreased in patients with diabetic nephropathy when compared with either CRF or diabetes.     

Phenytoin-Induced Bone Loss and Its Prevention with Alfacalcidol or Calcitriol in Growing Rats

Cathepsin K is a lysosomal cysteine proteinase (LCP) predominantly expressed in osteoclasts. This study was conducted to evaluate the improtance of human cathepsin K for osteoclastic bone resorption relative to that of other LCPs. To accomplish this, we quantitatively determined the expression levels of major LCPs (cathepsins B, K, L, and S) in human osteoclastic cells by using competitive RT-PCR. Giant cell tumor of bone (GCT) was used as a source of human osteoclastic cells, since the tissue was shown to contain a large number of cells satisfying the criteria for typical osteoclasts. The involvement of LCPs in the bone-resorption process by the GCT cells was confirmed by showing thattrans-epoxysucciny-l-leucylamido-(4-guanidino) butane (E-64), a nonselective cysteine proteinase inhibitor, exerted an inhibitory effect on the pit formation. We isolated osteoclast-like cells (OLCs) positive for tartrate-resistant acid phosphatase (TRAP) and cathepsin K from the GCT tissue to a degree of almost 95% purity. In these cells, the expression of cathepsin K was shown to be approximately 20-, 130-, and 410-fold stronger than that of cathepsins B, L, and S, respectively. A similar result was obtained when human bone marrow cells in culture were used as another source of OLCs. Further, we found that cathepsin K was expressed in OLCs far more strongly than in several human nonosteoclastic cells including osteoblastic cell lines. The abundant and selective expression of cathepsin K in OLCs relative to that of other LCPs suggests that cathepsin K is mainly responsible for osteoclastic degradation of human bone matrix.     

激素性股骨头坏死患者骨组织MMP-2、MMP-9、TIMP-1、TIMP-2蛋白的表达

目的观察激素性股骨头坏死患者股骨头骨组织中基质金属蛋白酶-2（MMP-2）、基质金属蛋白酶-9（MMP-9）、基质金属蛋白酶组织抑制剂-1（TIMP-1）、基质金属蛋白酶组织抑制剂-2（TIMP-2）蛋白表达情况,探讨糖皮质激素对MMPs/TIMPs系统的影响,及其与股骨头坏死的相互关系。方法 2007年3月-2008年3月,取激素性股骨头坏死患者股骨头骨组织35例和股骨颈骨折患者股骨头骨组织21例,分别作为试验组和对照组。两组男女比例均为4：3;年龄41～70岁,其中试验组平均55.34岁,对照组平均55.33岁;试验组最近2年内接受过皮质激素治疗超过3周或超过1周的大剂量冲击治疗,对照组从未接受过超过1周的激素治疗。所有标本行多聚甲醛固定后石蜡包埋,HE染色及蛋白提取,采用蛋白免疫印迹（Westernblot）技术检测MMP-2、MMP-9、TIMP-1、TIMP-2蛋白的表达水平并求出MMPS/TIMPS比值。结果 HE染色：试验组未见完整的骨小梁和骨单位,可见不连续的骨碎片,碎片骨陷窝内骨细胞大部分消失,周围有大量炎性肉芽组织。对照组可见完整骨单位由板层骨构成,板层骨连续完整,围绕血管呈同心圆排列,小梁骨陷窝内可见骨细胞。Westernblot检测：激素组与对照组比较,MMP-2、MMP-9蛋白表达增高,TIMP-1、TIMP-2蛋白表达水平降低,差异有统计学意义（P〈0.05）。结论长期应用糖皮质激素致股骨头坏死的效应可能与其调控MMPs/TIMPs系统表达有关。     

Immunohistochemical analysis of TIMP-2 and collagen types I and IV in experimental spinal cord ischemia-reperfusion injury in rats

Background

Thoracic and thoracoabdominal aortic intervention carries a significant risk of spinal cord ischemia. The pathophysiologic mechanisms that cause hypoxic/ischemic injury to the spinal cord have not been totally explained. In normal spinal cord, neurons and glial cells do not express type IV collagen. Type IV collagen produced by reactive astrocytes is reported to participate in glial scar formation. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors that regulate the activity of the matrix metalloproteinases (MMPs). TIMP-2 binds strongly with MMP-2, facilitating activation by membrane-type MMP. Imbalance between TIMPs and MMPs can lead to excessive degradation of matrix components. Type IV collagen involved in the blood–brain barrier disruption and glial scar formation, TIMP-2 influences MMP-2 that controls degradation of collagen I and IV.

Objective

To examine the immunohistochemical analysis of TIMP-2 and collagen types I–IV in experimental spinal cord ischemia–reperfusion in rats.

Methods

Thirty-two male Wistar rats weighing 250–300 g were divided into four groups: group S: sham group (n = 8); group 0P: 30-minute occlusion without perfusion (n = 8); group 3P: 30-minute occlusion and 3-hour perfusion (n = 8); and group 24P: 30-minute occlusion and 24-hour perfusion (n = 8). Infrarenal aorta was cross-clamped at two sites by using two aneurysm clips for 30 minutes. Reperfusion was provided after removal of the clips. Lumbar spinal cord segments were removed for immunohistochemical analysis.

Results

TIMP-2 and collagen staining in 3-hour perfused (3P) group were nearly the same with sham group (S). TIMP-2 and collagen staining increased in the 24-hour perfused group.

Conclusion

Alterations in collagen levels may relate to the biphasic breakdown of the blood–brain barrier and collagen staining in new cell types with relation to glial scar formation. Our results demonstrate that 3-hour perfusion after occlusion in hypoxic/ischemic spinal cord injury seems to be the critical reversible period.     

MMP-9和TIMP-1在人结核性淋巴结中的表达及临床意义

目的探讨基质金属蛋白酶9(MMP9)及其组织抑制物(TIMP1)在人结核性淋巴结中的表达及其临床意义。方法免疫组化SP法检测MMP9和TIMP1蛋白在20例活动性淋巴结结核、20例陈旧性结核性淋巴结病灶和20例慢性非特异性淋巴结炎中的表达,采用图象分析技术对免疫组化结果进行定量分析。结果MMP9和TIMP1在三组淋巴结病变均有表达,其中MMP9在活动性淋巴结结核的肉芽肿、坏死周围炎性区呈强表达,在非特异性淋巴结炎和陈旧性结核病灶呈弱表达。MMP9,TIMP1及MMP9/TIMP1在活动性结核组表达显著高于非特异性淋巴结炎和陈旧性结核病灶(均为P<0.01),在单纯活动性淋巴结核组和合并活动性肺结核组表达无显著性差异(均为P>0.05)。结论MMP9、TIMP1高表达可能在结核性淋巴结炎发病机制中发挥重要作用,MMP9/TIMP1失衡可能预示疾病进展和结核播散。     

Monocytes mediate osteoclastic bone resorption by prostaglandin production

Summary Monocytes are frequently found adjacent to active bone resorption surfaces in both physiological and pathological situations and may play a key role in bone resorption. There is strong circumstantial evidence that monocytes are precursors for osteoclasts in vivo, and recently they have been shown to resorb devitalized bone directly. The present study shows that monocytes can also resorb bone by stimulation of osteoclasts. Live fetal rodent bones prelabeled with⁴⁵Ca and cultured for 48–96 h in the presence of human monocytes or monocyte-conditioned medium released 80% more mineral than bones cultured in control medium. Bone matrix sustained comparable resorption as demonstrated by a 2-fold decrement in the extracted dry weights of the bones cultured in monocyte-conditioned medium. Histological examination of the bones cultured with monocytes or monocyte-conditioned medium showed increased osteoclast number and activity when compared with bones cultured in control medium. Known inhibitors of osteoclastic activity (phosphate 6 × 10⁻³M, cortisol 10⁻⁶M, and calcitonin 50 mU/ml) inhibited monocyte-conditioned medium-mediated bone resorption. The monocyte-conditioned medium contained sufficient prostaglandin E to account for the bone resorption. Indomethacin 10⁻⁵M added to the monocyte cultures blocked monocyte-conditioned media-induced bone resorption and prostaglandin release. These experiments suggest that monocytes stimulate osteoclastic bone resorption by prostaglandin production. Monocyte-induced bone resorption is partly reversed by inhibitors of osteoclast function. Monocyte-induced osteoclastic bone resorption may play an important role in physiologic bone remodeling and in bone destruction that occurs in chronic inflammatory diseases such as rheumatoid arthritis and periodontal disease.     

Ibuprofen inhibits localized bone resorption in the middle ear

Summary Localized osteoclastic bone resorption plays a significant role in the pathogenesis of several diseases of the middle ear as well as orthodontic tooth movement and long bone remodeling. The mechanisms of control of localized bone loss and systemic bone resorption may be different but both may be mediated by a final common pathway which includes prostaglandins. Prostaglandins seem to have a predominantly stimulatory effect on bone resorption, although the exact mechanism is poorly understood. Ibuprofen, a nonsteroidal antiinflammatory drug, is known to inhibit the synthesis of prostaglandins. It is likely that ibuprofen, through its inhibition of prostaglandin synthesis, would decrease the localized osteoclastic bone resorption in a previously described animal model system. Mongolian gerbils were divided into three groups: low dose ibuprofen (10 mg/kg per day), high dose ibuprofen (30 mg/kg per day), and a control group. Following surgical implantation of catheters to the right bullae of each gerbil, pressure was applied for 8 days, stimulating osteoclastic bone resorption. After killing the animals and histomorphometric analysis of the bullae from each, comparisons were made between each group using osteoclast surface (percentage of bone area covered by osteoclasts), osteoclast number (number of osteoclasts/mm bone length), and osteoclast profile area (in μm²). Significantly lower osteoclast surface (Oc. S/BS) was found in pressurized bullae from both treatment groups when compared with pressurized bullae from controls (P<0.05) and significantly lower osteoclast number (N.Oc/T.L) in pressurized bullae from both treatment groups when compared with pressurized bullae from controls (P<0.05). These differences were found to be dose-dependent. No significant differences in individual osteoclast profile area were found in either treatment group when compared with controls.     

Immunohistochemical analysis of TIMP-2 and collagen types I and IV in experimental spinal cord ischemia–reperfusion injury in rats

Abstract

Background

Thoracic and thoracoabdominal aortic intervention carries a significant risk of spinal cord ischemia. The pathophysiologic mechanisms that cause hypoxic/ischemic injury to the spinal cord have not been totally explained. In normal spinal cord, neurons and glial cells do not express type IV collagen. Type IV collagen produced by reactive astrocytes is reported to participate in glial scar formation. Tissue inhibitors of metalloproteinases (TIMPs) are endogenous inhibitors that regulate the activity of the matrix metalloproteinases (MMPs). TIMP-2 binds strongly with MMP-2, facilitating activation by membrane-type MMP. Imbalance between TIMPs and MMPs can lead to excessive degradation of matrix components. Type IV collagen involved in the blood–brain barrier disruption and glial scar formation, TIMP-2 influences MMP-2 that controls degradation of collagen I and IV.

Objective

To examine the immunohistochemical analysis of TIMP-2 and collagen types I–IV in experimental spinal cord ischemia–reperfusion in rats.

Methods

Thirty-two male Wistar rats weighing 250–300 g were divided into four groups: group S: sham group (n = 8); group 0P: 30-minute occlusion without perfusion (n = 8); group 3P: 30-minute occlusion and 3-hour perfusion (n = 8); and group 24P: 30-minute occlusion and 24-hour perfusion (n = 8). Infrarenal aorta was cross-clamped at two sites by using two aneurysm clips for 30 minutes. Reperfusion was provided after removal of the clips. Lumbar spinal cord segments were removed for immunohistochemical analysis.

Results

TIMP-2 and collagen staining in 3-hour perfused (3P) group were nearly the same with sham group (S). TIMP-2 and collagen staining increased in the 24-hour perfused group.

Conclusion

Alterations in collagen levels may relate to the biphasic breakdown of the blood–brain barrier and collagen staining in new cell types with relation to glial scar formation. Our results demonstrate that 3-hour perfusion after occlusion in hypoxic/ischemic spinal cord injury seems to be the critical reversible period.     

Tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) distribution in normal and pathological human bone

Degradation of skeletal connective tissue is regulated, at least in part, by the balance between matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinase (TIMPs), their natural inhibitors. The balance between MMPs and TIMPs may therefore be a determinant of normal bone turnover, and imbalance could thus lead to reduced organization of bone structure. To test this hypothesis, the cellular expression of MMPs and TIMP-1 was investigated by immunohistochemistry in human neonatal rib and osteophytic and heterotopic bone; these differ in their structure, with heterotopic bone showing the least and normal rib the most organized development. In all samples, high levels of MMPs were expressed. Collagenase and stromelysin-2 were detected in chondrocytes, osteoblasts, and osteoclasts, whereas gelatinase-B was confined to osteoclasts and mononuclear cells. Matrix-associated stromelysin-1 was present in fibrous tissue and osteoid. In contrast, the expression of TIMP-1 varied markedly between the three types of bone. In heterotopic bone only occasional low level TIMP-1 expression was detected in chondrocytes and osteoblasts. Osteophytic bone showed varying levels of TIMP-1, which was matrix-bound in fibrous tissue and cell-associated in osteoblasts, chondrocytes, and occasional mononuclear cells. In both types of bone, expression of TIMP-1 by osteoclasts was absent despite large numbers of these cells. Neonatal rib bone showed consistent expression of TIMP-1, particularly in chondrocytes, osteoblasts, and lining cells. In contrast to pathological bone, many osteoclasts were TIMP-1 positive. These results suggest that, in heterotopic and osteophytic bone, the low levels of TIMP-1, and in particular its absence in osteoclasts, may partly explain the more poorly organized bone formation in these pathological bone samples. Furthermore, TIMP-1 may play a role in the regulation of bone modeling and remodeling in normal developing human bone.     

Nitric oxide modulates renal vasoconstrictor effect of endothelin-1 in conscious lambs

To test the hypothesis that nitric oxide (NO) buffers the renal vasoconstrictor effects of endothelin-1 (ET-1) early in life, renal haemodynamic responses to ET-1 were measured in the presence and absence of endogenously produced NO in conscious lambs. Renal haemodynamic effects of ET-1 were measured for 5 min before (control) and 20 min after intraarterial injection of ET-1 before and after pretreatment with 20 mg/kg of the l-arginine analogue N^G-nitro-l-arginine methyl ester (l-NAME), (experiment 1) and its inactive isomer D-NAME (experiment 2) in conscious lambs aged ~1 week (N=7) and ~6 weeks (N=6). The two experiments were carried out in random order at intervals of 24–48 h. In lambs aged ~6 weeks, a marked increase in renal vascular resistance (RVR) was elicited by ET-1 administration; this response was enhanced twofold following pretreatment with l-NAME. In 1-week-old lambs, however, an increase in RVR in response to ET-1 occurred only after pretreatment with l-NAME. Therefore, we accept our hypothesis and conclude that NO buffers the renal vasoconstrictor effects of ET-1 early in life.The current address of Dr. Liesbeth van der Velde is UCLA Medical Center, Los Angeles, CA, USA. The current address of Dr. Alp Sener is University of Western Ontario, London, ON, Canada     

Supplementation of l-arginine prevents glucocorticoid-induced reduction of bone growth and bone turnover abnormalities in a growing rat model

The present study was designed to evaluate the effects of glucocorticoid (GC) treatment on bone turnover and bone mineral density in the growing rat. Because of the recent evidence that nitric oxide (NO) can counteract prednisolone-induced bone loss in mature rats, we examined the effect on bone of the NO donor l-arginine in young male rats, in which bone mass is increased by the same biological mechanism as in children and adolescents. Thirty-six 10-week-old Sprague-Dawley male rats were assigned to six groups of six animals each, and treated for 4 weeks with either vehicle (once a week subcutaneous injection of 100µl of sesame oil); prednisolone sodium succinate, 5mg/kg, 5 days per week by intramuscular injection (i.m.); l-arginine, 10mg/kg intraperitoneally (i.p.) once a day; N^G-nitro-l-arginine methylester (l-NAME), 50mg/kg subcutaneously once a day; prednisolone sodium succinate 5mg/kg, 5 days per week i.m. +l-arginine 10mg/kg i.p. once a day; or prednisolone sodium succinate, 5mg/kg, 5 days per week i.m. +l-NAME 50mg/kg subcutaneously once a day. Serum calcium, alkaline phosphatase (ALP), osteocalcin, and the C-terminal telopeptides of type I collagen (RatLaps) were measured at baseline conditions and after 2 and 4 weeks. Prior to treatment, and after 2 and 4 weeks, the whole body, vertebral, pelvic, and femoral bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) scanning. Prednisolone and prednisolone + l-NAME treated rats had significantly lower ALP and osteocalcin levels than controls at 2 and 4 weeks, and significantly higher levels of Rat-Laps than controls at 4 weeks. Prednisolone, l-NAME, and prednisolone + l-NAME produced a significant inhibition of bone accumulation and bone growth at all sites measured. Supplementation with l-arginine appeared to prevent the inhibition of bone growth and increase in bone resorption induced by prednisolone. These data would suggest, for the first time, that supplementation with an NO donor could be considered as a treatment for steroid-induced osteoporosis in the developing skeleton.     

Scavengers protection of cells against ALA-based photodynamic therapy-induced damage

. The exogenously stimulated formation of intracellularly generated protoporphyrin IX, a precursor of haem, is becoming one of the fastest developing areas in the field of photodynamic therapy (PDT). We tested the action of several free radical scavengers, amino acids, antioxidants and sulphur-containing compounds as protectors from photodamage induced by 5-aminolaevulinic acid (ALA)-mediated PDT, employing the LM2 cell line, derived from a mammary murine adenocarcinoma. We exposed the cells to different concentrations of the compounds, 24 h before PDT, during PDT, and 19 h after treatment. We defined the protection grade (PG) as the ratio between cell survival after ALA-PDT treatment in the presence of the protector and cell survival of ALA-PDT treatment alone. We found thatl -tryptophan (PG=9.2 at 2 mm ), reduced glutathione (GSH) (PG=5.8 at 0.8 mm ), N-acetyl-l -cysteine (PG=4.86 at 30 mm ), melatonin (PG=4.5 at 8 mm ) andl -methionine (PG=4.0 at 0.8 mm ) are the best protectors from PDT damage, followed byl -cysteine (PG=2.8 at 0.8 mm ), mannitol (PG=2.6 at 20 mm ) and glycine (PG=2.4 at 40 mm ) whereas oxidised glutathione and S-adenosyl-l -methionine do not exert any protection. We did not found any photoactive action of the protectors in absence of ALA. These results can be considered to modulate the photodamage induced by ALA-PDT. Paper received 24 October 2001; accepted after revision 5 May 2002. Correspondence to: Professor A. Batlle, Viamonte 1881 10A, 1056 Buenos Aires, Argentina. Fax: 54 11 4811 7447; e-mail: batlle@mail.retina.ar     

Restoration of euthyroidism accelerates bone turnover in patients with subclinical hypothyroidism: a randomized controlled trial

This study evaluated the effect of physiological l-thyroxine (L-T4) treatment on bone metabolism in patients with subclinical hypothyroidism. Sixty-six women with subclinical hypothyroidism (TSH 11.7 ± 0.8 mIU/l) were randomly assigned to receive L-T4 or placebo for 48 weeks. Sixty-one of 66 patients completed the study. Individual L-T4 replacement (mean dosage 85.5 ± 4.3 g/day) was performed targeting euthyroid thyroid-stimulating hormone (TSH) levels. The primary outcome measure was 24- and 48-week change in markers of bone formation (total and bone alkaline phosphatase [ALP, bone ALP], osteocalcin [OC]) and resorption (pyridinoline [PYD] and deoxypyridinoline [DPD], C-terminal cross-linking telopeptide type I [CTX]). Secondary outcomes were 48-week changes in bone mineral density (BMD) of the lumbar spine and hip, measured by dual-energy X-ray absorptiometry. Compared with placebo, l-thyroxine (n=31) resulted in significant activation of bone turnover. Overall, a significant treatment effect was observed for DPD (between-group difference 16.0%; 95%CI, 10.9 to 21.1), CTX (29.9%; 95%CI, 23.3 to 36.5), and bone ALP (13.2%; 95%CI, 6.6 to 19.7) after 24 weeks. At the end of the study, lumbar BMD in the both treatment groups differed by 1.3% (95%CI, –2.9 to 0.5) with lower levels in l-thyroxine treated women. Significant difference in BMD between groups was also observed at the trochanter. We conclude that physiological l-thyroxine treatment accelerates bone turnover reflecting early activation of bone remodeling units in the initial replacement of subclinical hypothyroidism. The observed bone loss could be interpreted as an adaptive mechanism on decreased bone turnover in preexistent hypothyroidism, and not as l-thyroxine-induced clinically important bone loss. However, long-term studies are needed to confirm this assumption.This work was supported by grants from the Swiss National Science Foundation (32.27866.89, 32.37792.93, and 32.37792.98) and unconditional research grants from Henning Berlin, Sandoz Research, and Roche Research foundations. Presented in part at the 24th annual meeting of the American Society for Bone and Mineral Research, San Antonio, 2002, and at the 84th annual meeting of The Endocrine Society, San Francisco, 2002.     

A novel role of l-serine (l-Ser) for the expression of nuclear factor of activated T cells (NFAT)2 in receptor activator of nuclear factor κB ligand (RANKL)-induced osteoclastogenesis in vitro

Multinucleated cell formation is crucial for osteoclastogenesis, and the expression of nuclear factor of activated T cells (NFAT)2 (NFATc1) is essential for this process. We previously found, using mouse RAW264 cells, that culture at high cell density blocked progression to the multinucleated cell stage induced by stimulation with receptor activator of nuclear factor κB ligand (RANKL). Here, we have confirmed this finding in a bone marrow cell system and extended the analysis further. A high cell density appeared to cause a change in the composition of the culture medium accompanying downregulation of NFAT2 expression, and we identified l-serine (l-Ser) as essential for the expression of NFAT2 induced by RANKL. Namely, culture at high cell density caused a depletion of l-Ser in the medium. Consequently, l-Ser appeared to exert its effect at an early stage under the regular conditions used for inducing the expression of c-Fos, an upstream regulator of NFAT2. d-Ser, an enantiomer of l-Ser, showed no NFAT2-inducing activity. The expression of NFAT2, using a retrovirus vector, could compensate for the depletion of l-Ser and resume the progression to the multinucleated cell stage. These results demonstrate a novel role for l-Ser in RANKL-induced osteoclastogenesis in vitro.     

Inhibition of Liver Metastasis from Orthotopically Implanted Colon Cancer in Nude Mice by Transfection of the TIMP-1 Gene into KM12SM Cells

To determine whether the tissue inhibitor of metalloproteinases 1 (TIMP-1) can modulate in vivo tumor growth and metastasis, we transfected TIMP-1 cDNA into KM12SM human colon carcinoma cells and determined the implanted tumor volume and incidence of liver metastasis in orthotopically implanted colon cancer in nude mice. We also treated the implanted tumors with repeated intraperitoneal injections of recombinant human TIMP-1 (rTIMP-1), and compared the inhibitory efficacy on liver metastasis with that achieved by the TIMP-1 transfectants. The TIMP-1 transfectants had a significantly greater inhibitory effect, in association with TIMP-1 expression, on the growth of the primary tumor and on liver metastasis as compared with the controls. However, the intraperitoneal administration of rTIMP-1 did not decrease the rate of liver metastasis. In situ hybridization demonstrated that TIMP-1 mRNA in the cecal tumors implanted with the highly produced KM12SMT-2 cells with TIMP-1 was mainly expressed by the tumor cells. These results suggest that the increased expression of TIMP-1 in KM12SM cells was responsible for their decreased metastatic potential, and that the endogenous increase in TIMP-1 production by the tumor cells might be more effective for counteracting the matrix metalloproteinases (MMPs) in tumor tissue and for inhibiting liver metastasis from colon cancer than the exogenous administration of TIMPs. Received: May 8, 2000 / Accepted: March 6, 2001     

The Contribution of Familial Resemblance to Variation in Circulatory Levels of Tissue Inhibitors of Metalloproteinases and Transforming Growth Factor-?1

This study attempted to elucidate the genetic and environmental factors influencing interindividual variation of circulating TIMP-1, TIMP-2 and TGF-1 and to clarify the relationship between the latter biochemical indices and hand osteoarthritis in an ethnically homogeneous sample. Plasma levels of each of the above biochemical indices were measured in 401 healthy individuals (aged 18–75 years) belonging to 90 nuclear and more complex families. Variance component analysis showed that a major part of the interindividual differences in TGF-1, TIMP-1 and TIMP-2 levels was credibly attributable to genetic and familial factors. Adjusted for significant covariates, the putative genetic effects on the above three amounted to 0.40 ± 0.10, 0.47 ± 0.11 and 0.72 ± 0.10, respectively. Common environmental factors, shared by members of the same household, also contributed significantly (P < 0.01) to variation of each of the biochemical indices and explained between 27.6% (TIMP-2) and 38.7% (TGF-1) of their variation. A bivariate analysis revealed a strong and highly significant correlation between TIMP-1 and TGF-1 (r = 0.58, P < 0.001), which was due to common genetic and environmental sources (r_G = 0.62 ± 0.09, r_E = 0.31 ± 0.11, both P < 0.001). The analysis also detected modest but significant genetic correlation between TIMP-1 and TIMP-2 (r_G = –0.307 ± 0.108, P < 0.01). The present study evinces a strong genetic dependence for the plasma levels of both TIMPs and TGF-1 and provides a basis for the further analysis of genetic variation affecting and regulating the circulatory concentrations of TIMPs and TGF-1 in healthy humans.