Effects on bone marrow cells of oral treatment with podophyllotoxin derivatives in rheumatoid arthritis

SPG 827, a mixture of podophyllotoxin derivatives, has been thought to alleviate the symptoms of rheumatoid arthritis (RA) by arresting cell division in metaphase (i.e. resulting in an increase of the mitotic index) of rapidly proliferating cells of the immune apparatus. In contrast, the present study produced evidence that peroral SPG treatment of RA patients reduced the mitotic index of bone marrow cells, mainly in erythropoiesis. At the same time, slight megaloblastic changes appeared in the erythroblasts. These observations suggest that SPG treatment induced an interphase block in the G2 phase of the cell cycle, analogous to the cell action of the newer podophyllotoxin derivatives teniposide and etoposide. It may be that part of the clinical effect of SPG in rheumatoid arthritis is due to the described interphase-blocking activity.     

Pathogenesis of bone erosions in rheumatoid arthritis

Patients with rheumatoid arthritis are at risk for the development of a generalized form of bone loss affecting the axial and appendicular skeleton. In addition, juxta-articular osteopenia and focal erosion of marginal and subchondral bone are commonly seen. The pathogenesis of focal bone erosions is an area of active investigation. Studies of tissue sections from sites of bone erosion in rheumatoid arthritis and in animal models of inflammatory arthritis have identified multinucleated cells with the phenotype of osteoclasts in bone resorption lacunae in these sites, suggesting that osteoclasts mediate a component of this pathologic bone loss. Numerous soluble and cell-membrane factors produced by rheumatoid synovial tissues are likely to play a role in the initiation and progression of bone erosions. In addition, recent studies suggest a role for T lymphocytes and their products in osteoclast-mediated bone loss. This paper reviews the cellular mechanisms and factors implicated in bone erosions in rheumatoid arthritis, and discusses the possible therapeutic strategies suggested by these findings.     

Pathogenesis of bone lesions in rheumatoid arthritis

Histopathologic characterization of bone erosions from patients with rheumatoid arthritis (RA) and studies performed in animal models of inflammatory arthritis provide strong evidence that osteoclasts play an important role in focal marginal and subchondral bone loss in inflammatory arthritis. Much has been learned concerning the factors responsible for the induction and activation of osteoclasts associated with the bone erosions in RA. Therapies that target these osteoclast-inducing factors or other aspects of osteoclast-mediated bone resorption represent potential targets for blocking or at least attenuating bone destruction in RA. The demonstration of the role of the newly described osteoclastogenic factor receptor activator of nuclear factor kappaB ligand in RA synovial tissues and the successful prevention of bone erosions in animal models of arthritis with its inhibitor osteoprotegerin provide hope that specific therapies can be developed for preventing bone and joint destruction in RA, particularly in situations in which disease-modifying agents are ineffective in controlling disease activity.     

Hormonal preservation of bone in rheumatoid arthritis

Bone loss is a hallmark of RA. Factors influencing generalized bone loss include RA-specific factors such as the influence of disease activity and deficient sex hormone status and more general mechanisms (e.g., due to the use of glucocorticoids). Reducing disease activity has a positive effect on bone. Estrogens or androgens can restore deficiency of the sex hormones with a small positive effect on BMD. The more pronounced bone loss occurs when RA patients are being treated with glucocorticoids. This bone loss can be reduced by the concomitant use of calcium and vitamin D and, in most patients, by the use of bisphosphonates as well.     

针灸治疗类风湿关节炎的临床研究

目的　了解针灸治疗类风湿关节炎 (RA)的疗效 ,并探讨其消炎镇痛作用机制。方法　将 45例RA患者随机配对以 1∶2分为针灸组 (30例 )和消炎痛组 (15例 )。观察其疗效并测定部分患者治疗前后超氧化歧化酶 (SOD)、脂质过氧化物酶 (LPO)的改变和亮脑啡肽 (LEK)的变化。结果　针灸组与消炎痛组治疗RA疗效相似 (P >0 0 5 ) ,治疗前后的关节肿胀指数、关节压痛指数、晨僵、握力、红细胞沉降率 (ESR)、类风湿因子 (RF)均下降。治疗前后SOD和LPO降低 ,而LEK明显升高。结论　针灸治疗RA具有消炎镇痛作用 ,其机制可能与亮脑啡肽升高 ,调节自由基代谢有关 ,同时发现针灸治疗能使ESR明显下降 ,RF滴度下降 ,可能还有免疫调节作用     

Mechanisms of bone loss in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease in which destruction of bone in the joints causes major morbidity. Recent research has shed light on the cell and molecular mechanisms that lead to this osteolysis, all due directly or indirectly to the chronic inflammation. The aspects of this research covered in this review include the alteration of cell proliferation and survival that results in growth of the RA synovium. This process depends upon an increase in angiogenesis and local blood flow, which is also a feature of increased bone turnover. In addition, the inflammatory environment increases expression of chemokines, which are involved in the recruitment of monocytic osteoclast precursors. Chronic inflammation also promotes an overall catabolic state, with increased osteoclast differentiation and resorptive activity, driven by disregulation of receptor activator of NF-κB ligand (RANKL) and the synergistic activity of inflammatory cytokines such as tumor necrosis factor-α and interleukin-1. Osteoclast survival is increased in this environment, but osteoblast differentiation and survival are decreased, with a consequent reduction in bone formation and a net loss of bone. Recognition of these processes and the factors involved will enable more effective and targeted treatments for RA.     

Pathogenesis of bone erosions in rheumatoid arthritis

Focal marginal joint erosions represent the radiographic hallmark of rheumatoid arthritis (RA). These bone changes are characteristically localized to the joint margins, but in addition, regions of focal bone resorption can be detected in the subchondral bone adjacent to the bone marrow space into which the synovial inflammatory tissues have extended. Because progressive destruction of the periarticular bone contributes significantly to joint dysfunction and disability in patients with RA, there is considerable interest in developing a better understanding of the pathologic mechanisms involved in this process and in developing therapies that can arrest these events. Previous analysis of joint tissues from patients with RA have provided morphologic evidence that osteoclasts are the cell types that mediate the focal bone resorption associated with the rheumatoid synovial lesion. Additional recent data from animal models have helped to further implicate these cells in the pathogenesis of focal bone erosions. Furthermore, analysis of RA synovium and joint tissues from animal models of inflammatory arthritis, as well as cell and tissues culture studies, have helped to define the cytokines and inflammatory mediators that are involved in the recruitment and activation of bone resorbing cells associated with focal bone erosions. These findings provide a rational framework for developing targeted therapies that can specifically inhibit or slow the progressive focal bone destruction associated with the rheumatoid synovial lesion.     

Mechanisms of bone loss in rheumatoid arthritis

Abstract

Rheumatoid arthritis (RA) is an autoimmune inflammatory disease in which destruction of bone in the joints causes major morbidity. Recent research has shed light on the cell and molecular mechanisms that lead to this osteolysis, all due directly or indirectly to the chronic inflammation. The aspects of this research covered in this review include the alteration of cell proliferation and survival that results in growth of the RA synovium. This process depends upon an increase in angiogenesis and local blood flow, which is also a feature of increased bone turnover. In addition, the inflammatory environment increases expression of chemokines, which are involved in the recruitment of monocytic osteoclast precursors. Chronic inflammation also promotes an overall catabolic state, with increased osteoclast differentiation and resorptive activity, driven by disregulation of receptor activator of NF-κB ligand (RANKL) and the synergistic activity of inflammatory cytokines such as tumor necrosis factor-α and interleukin-1. Osteoclast survival is increased in this environment, but osteoblast differentiation and survival are decreased, with a consequent reduction in bone formation and a net loss of bone. Recognition of these processes and the factors involved will enable more effective and targeted treatments for RA.     

Measures of bone loss in rheumatoid arthritis

Patients with rheumatoid arthritis (RA) are prone to develop osteoporosis, especially women receiving steroid hormone therapy. Inhibition of bone formation and/or excessive bone resorption may be responsible. Bone gamma-carboxyglutamic acid-containing protein (BGP), the major noncollagen protein of bone and a plasma marker of bone formation, was measured in 81 consecutive RA patients and 79 age- and sex-matched control subjects, in addition to the hormone regulators of bone metabolism, calcitonin, parathyroid hormone, and 1,25-dihydroxyvitamin D. Mean (+/- SE) BGP levels (picomoles per milliliter) were lower for RA men (1.46 +/- 0.14) and women (1.52 +/- 0.2) compared with their respective controls (2.05 +/- 0.17 for men, 2.47 +/- 0.22 for women). Women taking steroids had the lowest levels (1.13 +/- 0.22) and, in contrast to men, this value was lower than the nonsteroid-treated group. Steroid treatment appears to be a major determinant of low BGP levels; the effect of RA itself is suspected but not proved in this study. Calcitonin levels were lower in RA men as well as in all women. Diminution of BGP in these subjects supports the view that "low-dose" corticosteroid treatment may suppress bone formation, especially in women. Prevention or remediation of osteopenia may be monitored by BGP, if further studies validate this hypothesis with other measures of skeletal mass.     

Mechanism of bone destruction in rheumatoid arthritis

Osteoclasts play a critical role in bone destruction in rheumatoid arthritis. Activation of osteoclastogenesis is mediated by the enhanced expression of RANKL (receptor activator of NF-kappaB ligand), accompanied by reduced expression of its inhibitor, IFN-gamma. Accumulating evidence indicates that the osteoclast-targeted therapy is effective in arthritis models, suggesting a promising new strategy for rheumatoid bone destruction.     

Effects of different regimes of corticosteroid treatment on calcium and bone metabolism in rheumatoid arthritis

Summary A clinical study of 30 patients with rheumatoid arthritis was undertaken in order to assess the acute effects of corticosteroids on calcium and bone metabolism. The patients were randomly divided into 3 groups. The first group was not treated with corticosteroids, the second group was treated with 3 oral pulses of 100 mg prednisolone and the third group received 3 intravenous pulses of 1000 mg methylprednisolone (MP) on alternate days during one week. In both steroid treated groups the serum parathyroid hormone concentration tended to increase. In the MP treated group an increase in the 1.25-dihydroxyvitamin D concentration after the first pulse was followed by a significant drop; this effect was also seen, but somewhat retarded and less distinct, in the orally treated group. In the MP treated group the urinary calcium excretion raised significantly 6 hrs after the first pulse and then dropped significantly. In all groups no changes were found in the serum calcium level and the urinary excretion of hydroxyproline. We conclude that, acute changes in calcium and bone metabolism occur during treatment with intravenous pulses of methylprednisolone and with oral pulses of prednisolone. These changes are small and reversible in a few days.     

Rapid periarticular bone loss in rheumatoid arthritis

For approximately 2 years, bone loss was measured in women with early stages of rheumatoid arthritis (RA) and in control subjects, using serial computed tomography and dual photon absorptiometry. Rapid trabecular bone loss from the distal radius was observed in the RA patients but not the controls. The bone loss correlated with initial plasma levels of parathyroid hormone and 1,25-dihydroxyvitamin D₃ (calcitriol) concentrations. It has been suggested that these humoral factors may interact with cytokines or other mediators produced in the adjacent wrist joint. Losses of the cortical bone of the radial midshaft and the lumbar spine were modest and were comparable in the 2 groups. Indices relating to both bone formation and bone resorption predicted bone loss at these 2 sites, but changes in the parathyroid hormone and calcitriol concentrations did not.     

Determinants of axial bone loss in rheumatoid arthritis

To assess mechanisms that cause generalized osteoporosis in rheumatoid arthritis (RA), we measured bone mineral density (BMD) by dual photon absorptiometry in the lumbar spine and femoral neck of 111 patients with RA. BMD was significantly reduced at both sites in these patients. Physical activity correlated significantly with BMD in patients with RA, and was found, by multiple regression analysis, to be a significant predictor of femoral bone density in female patients. Multiparity exerted a protective effect on lumbar bone density. Prednisolone (mean dosage 8 mg/day) was not associated with significantly increased bone loss in women, whereas higher dosages in men (mean 10.3 mg/day) were associated with increased lumbar bone loss. Reduced physical activity leading to a form of disuse osteoporosis appears to be an important factor in axial bone loss in RA.     

类风湿关节炎患者骨质疏松与骨侵蚀关系的研究

目的 探讨类风湿关节炎(RA)患者骨质疏松的发生情况及其与关节骨侵蚀及其他临床指标的相关性.方法 采用双能X线骨密度仪.测量111例RA患者和30名健康人腰椎和股骨区的骨密度(BMD),并同时测定手关节X线分期及其他各临床指标.结果 RA患者的骨量丢失较对照组明显,骨质疏松的患病率更高(P＜0.05),随关节骨侵蚀加重,各测定部位的BMD呈下降趋势,手关节病变Ⅲ期、Ⅳ组的BMD均明显低于对照组(P＜0.05).RA患者中骨质疏松组较非骨质疏松组病程更长(P＜0.05),手关节骨侵蚀更重(P＜0.05),关节功能更差(P＜0.05).服用糖皮质激素比例更高(P＜0.05).Logistic回归分析显示手关节骨侵蚀(OR=0.636,0.424～0.954,P=0.029)和糖皮质激素服用情况(OR=2.696,1.026～7.083,P=0.044)是与RA患者骨质疏松发生有显著相关的因素.结论 随手关节骨侵蚀加蕈RA患者BMD呈下降趋势,RA患者骨质疏松的发生是多因素的,主要与关节骨侵蚀和是否服用糖皮质激素等有关.     

Effects of low dose corticosteroids on bone mass in rheumatoid arthritis: a longitudinal study.

Low dose corticosteroids are effective in suppressing synovitis in rheumatoid arthritis (RA), but there remains concern about their side effects, particularly osteoporosis. To examine the effects of low dose corticosteroids on bone loss in RA bone mineral density (BMD) was measured in the lumbar spine and hip for up to two years in 15 patients treated with these agents (mean dose prednis(ol)one 6.6 mg/day). 15 patients not receiving them, and 15 age matched controls. The initial BMD at both skeletal sites was significantly reduced in both patient groups compared with controls. The mean change in bone density was 0.2, 0.1, and -0.1% a year in the spine and -2.0, -1.9, and -1.0% a year in the hip respectively for the three groups. These rates of bone loss were not significantly different between groups at either site. These findings suggest that low dose corticosteroid treatment in RA is not associated with an increased risk of osteoporosis.     

Osteocalcin and bone mineral content in rheumatoid arthritis

Summary Abnormal bone metabolism was reported in rheumatoid arthritis (RA). In order to evaluate the interest of serum osteocalcin, also called bone GLA- protein (BGP), to assess bone metabolism in RA, we studied 20 postmenopausal RA out- patients and 20 matched controls. Nine patients were treated with low- dose corticosteroids (C₊)for at least one year (< 10 mg/day, prednisolone equivalent), the remaining 11 (C–) received non-steroidal anti-inflammatory drugs (NSAID). The distal and proximal forearm bone mineral content (BMC) was measured by single photon absorptiometry, the vertebral BMC was measured by dual photon absorptiometry. A trend to low BGP was observed in the C+ group. The lowest values were observed in patients with vertebral fractures. Compared with controls, both RA groups had similar low significant BMC at the forearm sites. At the vertebral sites, the bone mineral content decrease observed in the two groups, was more marked in the C+ group. From our results, BGP did not appear as a useful index of osteoporosis in RA, except in some patients with vertebral fractures, treated with low-dose corticosteroids.