Osteoblast role in the pathogenesis of rheumatoid arthritis.

In the pathogenesis of several rheumatic diseases, such as rheumatoid arthritis, spondyloarthritis, osteoarthritis, osteoporosis, alterations in osteoblast growth, differentiation and activity play a role. In particular, in rheumatoid arthritis bone homeostasis is perturbed: in addition to stimulating the pathologic bone resorption process performed by osteoclasts in course of rheumatoid arthritis, proinflammatory cytokines (such as Tumor Necrosis factor-α, Interleukin-1) can also inhibit osteoblast differentiation and function, resulting in net bone loss. Mouse models of rheumatoid arthritis showed that complete resolution of inflammation (with maximal reduction in the expression of pro-inflammatory factors) is crucial for bone healing, performed by osteoblasts activity. In fact, abnormal activity of factors and systems involved in osteoblast function in these patients has been described. A better understanding of the pathogenic mechanisms involved in osteoblast dysregulation could contribute to explain the generalized and focal articular bone loss found in rheumatoid arthritis. Nevertheless, these aspects have not been frequently and directly evaluated in studies. This review article is focused on analysis of the current knowledge about the role of osteoblast dysregulation occurring in rheumatoid arthritis: a better knowledge of these mechanisms could contribute to the realization of new therapeutic strategies.

Osteoporosis and rheumatic diseases.

Numerous rheumatic diseases, including rheumatoid arthritis, juvenile idiopathic arthritis, psoriatic arthritis, ankylosing spondylitis, systemic lupus erythematosus, systemic sclerosis, dermatomyositis/polymyositis and vasculitis are characterized by osteoporosis and fragility fractures. Inflammatory cytokines, glucocorticoid treatment, immobilization and reduced physical activity due to painful joints and muscle weakness are considered the main risk factors that cause low body mass density values in these diseases. Emerging evidence highlights the role of inflammatory cytokines, such as tumor necrosis factor (TNF)-α, interleukin (IL)-1, IL-6, IL-7 and IL-17, in the regulation of the bone homeostasis. In fact, chronic inflammation is often characterized by an imbalance between bone formation and bone resorption with a net prevalence of osteoclastogenesis, which is an important determinant of bone loss in rheumatic diseases.

Melkersson-Rosenthal syndrome in a patient with psoriatic arthritis receiving etanercept.

Melkersson-Rosenthal syndrome is a rare granulomatous neuro-mucocutaneous systemic disease that is characterized by relapsing peripheral facial paralysis, orofacial edema and fissured tongue. The disease etiology is still not well known, but it has been hypothesized that a possible role is played by various causal agents such as infectious diseases, genetic causes, allergic conditions, benign lymphogranulomatosis, various associations with other pathological conditions, particularly with immune-mediated diseases and food contact allergies. In this report we describe the case of a woman, 42 years old, with psoriatic arthritis who developed neurological episodes related to MRS after treatment with anti-TNF therapy. This finding further supports the hypothesis that TNF-alpha blockade, and particularly the use of the TNF-alpha receptor, could trigger the development of granulomatous lesions in predisposed patients. The case we report further sustains the importance for the clinician to take into account this potential adverse event in patients receiving anti-TNF-alpha therapies.

Dose-dependent metabolic effect of zoledronate on primary human osteoblastic cell cultures.

OBJECTIVES: To evaluate the in vitro effect of the bisphosponate zoledronate on metabolic activity, proliferation and viability of human osteoblasts. METHODS: Primary human osteoblasts cultures were obtained from cancellous bone of healthy subjects undergoing bone marrow biopsy. Cell cultures were treated with crescent concentrations of zoledronate (10⁻¹°to 10⁻³), with and without 1,25(OH)2 vitamin D3. In these experimental conditions we evaluated cells viability and proliferation using the MMT colorimetric test, cell apoptosis by measurement of Caspase 3 activity and metabolic cell activity through alkaline phosphatase activity and osteocalcin production. RESULTS: Osteocalcin and alkaline phosphatase synthesis was significantly enhanced by 10⁻¹° M to 10⁻5 M zoledronate concentrations, whereas was dramatically decreased by higher drug concentrations. Vitamin D3 enhanced the positive metabolic effect of zoledronate. The effect of zoledronate on cell proliferation was variable and dose-dependent. While no effect was observed with lower drug concentrations (10⁻¹° M to 10⁻8 M), zoledronate 10⁻7 M increased cell proliferation. Conversely, concentrations higher than 10⁻7 M significantly reduced cell proliferation, in a dose-dependent manner. Osteoblast apoptosis was enhanced after treatment with the highest zoledronate concentrations. The maximum positive effect on osteoblasts metabolic activity and proliferation was observed with the zoledronate concentrations corresponding to those theoretically reached in bone microenvironment when zoledronate is used in clinical practice for post-menopausal osteoporosis treatment. CONCLUSIONS: The results of this study confirm that bisphosphonates exert different cellular biochemical effects depending on dosage and support the hypothesis that their positive effect on bone mineral density could be partially due to an anabolic action on bone forming cells.

Two cases of distal extremity swelling with pitting oedema in psoriatic arthritis: the different pathological mechanisms.

In psoriatic arthritis, swelling and pitting oedema may be caused by different pathogenic mechanisms: on one hand, the involvement of tenosynovial structures; on the other hand, the involvement of lymphatic vessels, which may be rarely implicated by the inflammatory process. This different involvement is responsible for a different response to therapy and a different clinical outcome. In fact, patients with inflammation of the tenosynovial structures and normal lymphatic drainage have a more favourable clinical outcome and response to pharmacologic treatment, whilst patients affected by psoriatic arthritis with chronic lymphatic vascular damage are characterized usually by resistance of oedema to therapy. In this study, we report two cases of psoriatic arthritis with distal extremity swelling and pitting oedema. In the first patient, the swelling and pitting oedema were associated with lymphatic obstruction, as detected by lymphoscintigraphy. In the second, the predominant involvement of the tenosynovial structures, as shown by magnetic resonance, with normal lymphatic flow, may have been the cause of arthritis with oedema. These different pathogenetic mechanisms were associated with different response to therapy. Nevertheless, oedema was resistant to therapy in both patients probably because of other unknown factors, which influence therapy and clinical outcome.

Membranous nephropathy in rheumatoid arthritis: a case report.

Rheumatoid arthritis is a chronic disease characterized by inflammation, abnormal cellular and humoral immune responses, synovial hyperplasia and rarely by renal involvement, characterized principally by secondary amyloidosis and nephrotoxic effects related to drugs, while renal lesions directly due to the disease itself are infrequent. In this report we describe a patient with rheumatoid arthritis who developed membranous nephropathy associated with nephrotic syndrome while receiving adalimumab, an anti-tumour necrosis factor-alpha drug.

Normal and osteoporotic human osteoblast behaviour after 1,25-dihydroxy-vitamin D(3) stimulation.

In order to examine the effects of vitamin D on osteoblast function and to evaluate if osteoporotic and normal osteoblasts show a different behaviour in response to vitamin D, this report investigates the changes in osteocalcin production, after 1,25-dihydroxy-vitamin D(3) stimulation of cultured osteoblasts derived from osteoporotic patients. Our results indicate an inadequate osteoblastic function in osteoporosis and demostrate that 1,25-dihydroxy-vitamin D(3) can stimulate the metabolic activity of human osteoblasts in vitro. Considering that osteoporotic bone samples were representative of senile osteoporosis, our results may indicate a different metabolic phenotype in osteoporotic osteoblasts compared with normal osteoblasts. The increased osteocalcin production after 1,25-dihydroxy-vitamin D(3) stimulation of osteoporotic osteoblasts suggests a reduced, but not absent, anabolic function in senile osteoporotic osteoblasts. The results of this study confirm the validity of vitamin D(3) to treat senile osteoporosis and suggest the need of higher vitamin D(3) intake in senile osteoporotic patients than in younger subjects.

Clodronate inhibits angiogenesis in vitro and in vivo.

The effects of amino-bisphosphonate clodronate on endothelial cell functions involved in angiogenesis, namely proliferation and morphogenesis on matrigel were tested in vitro, whereas its effects on angiogenesis were studied in vivo. This was performed by using the chick embryo chorioallantoic membrane (CAM) assay. In vitro, clodronate inhibited the endothelial cell proliferation in a dose-dependent fashion, peaking at 30 microM. At the same concentration, clodronate inhibited the fibroblast growth factor-2 (FGF-2)-induced capillary-like tube formation in the morphogenesis assay on matrigel. In vivo, when tested with the CAM assay, clodronate again displayed the capability to inhibit FGF-2-induced angiogenesis. Overall, these results suggest that antiangiogenesis by clodronate can be used to treat a wide spectrum of angiogenesis-dependent diseases, including certain chronic inflammatory diseases and cancer.

Angiogenesis in vasculitides.

Vasculitides, including Wegener's granulomatosis, Takayasu's arteritis, giant cell arteritis, Kawasaki disease, Behçet disease, thromboangiitis obliterans and erythema elevatum diutinum, are inflammatory diseases of blood vessel wall characterized by myointimal proliferation, fibrosis and thrombus formation leading to stenosis or occlusion of the vascular lumen, and finally to tissue ischemia. In these diseases the hypoxic environment subsequent to stenosis or occlusion of the vascular lumen is a potent signal for the generation of new blood vessels. Angiogenesis may be a compensatory response to ischemia and to the increased metabolic activity and may be also a further inflammatory stimulus because endothelial cells of newly-formed vessels express adhesion molecules and produce colony-stimulating factors and chemokines for leukocytes.

Neridronate inhibits angiogenesis in vitro and in vivo.

The effects of the amino-bisphosphonate neridronate on endothelial cell functions involved in angiogenesis, namely, proliferation and morphogenesis on Matrigel were tested in vitro, whereas its effects on angiogenesis were studied in vivo, by using the chick embryo chorioallantoic membrane (CAM) assay. In vitro, neridronate inhibited endothelial cell proliferation in a dose-dependent fashion, peaking at 30 microM. At the same concentration, neridronate inhibited fibroblast growth factor-2 (FGF-2)-induced capillary-like tube formation in the morphogenesis assay on Matrigel. In vivo, when tested in the CAM assay, neridronate again displayed the capability to inhibit FGF-2-induced angiogenesis. Overall, these results suggest that anti-angiogenesis by neridronate could be used to treat a wide spectrum of angiogenesis-dependent diseases, including certain chronic inflammatory diseases and cancer.

Cervical myelopathy caused by periodontoid synovial pannus in a patient with psoriatic arthritis: a case report.

The atlantoaxial subluxation and the formation of a synovial periodontoid pannus are associated with rheumatoid arthritis causing mechanical compression of the spinal cord and cervical myelopathy. Atlantoaxial subluxation is very rare in psoriatic arthritis (PsA). Even more rare is the formation of a periodontoid synovial pannus associated with PsA and signs of myelopathy. In this report, cervical myelopathy caused by periodontoid synovial pannus in PsA is described.

Pubic symphysis sclerosis in psoriatic arthritis. Case report.

Pubic symphysis sclerosis is a very interesting event in psoriatic arthritis (PsA). PsA is a cronical arthritis, associated with psoriasis, classified with seronegative spondyloarthrities. There are 5 clinical PsA patterns: an oligoarticular pattern, characterized by asymmetrical involvement of metacarpophalangeal and interphalangeal joints of hands and feet, as well as ankles and knees; a polyarticular pattern; a pattern characterized by involvement of distal interphalangeal joints; an arthritis mutilans pattern, characterized by acro-osteolysis of distal phalanxes; a pattern with spondylitic involvement. Although pubic involvement in PsA is not described in literature, a lot of authors describe the presence of erosive and/or sclerotic osteitis pubis in seronegative spondyloarthrities, without a more accurate subclassification. In seronegative spondyloarthrities sclerotic involvement of pubic symphysis has been described in patients suffering from ankylosing spondylitis for 5-10 years. A case of pubic symphysis sclerosis, evident on radiographs and detected also by magnetic resonance, which shows also a pattern of oedema and enhancement, with increased signal intensity on pubic symphysis in T2-weighted images, after the contrast agent was injected in the bone marrow, is reported in a woman affected by PsA. Pubic symphysis sclerosis is atypical in PsA and may be considered, by analogy with ankylosing spondylitis, the final result of repairing mechanisms of the previous erosive changes.

[Thalidomide in treatment of connective diseases and vasculities]. / La talidomide nel trattamento delle connettiviti e delle vasculiti.

Thalidomide is an immunomodulatory, anti-inflammatory and anti-angiogenic drug. Thalidomide exerts its effects by decreasing circulating CD4 positive T-cells and stimulating CD8 positive T-cells, by increasing the number of Natural Killer cells and T-helper 2 cells. Thalidomide also inhibits proliferation of stimulated T-cells and leukocyte chemotaxis. It modifies a number of integrin receptors and other leukocytic surface receptors and down-modulates cell-adhesion molecules involved in leukocyte migration. It has been demonstrated that thalidomide inhibits TNFalpha, IL-5, IL-6, IL-8, IL-12 production and increases production of IL-2, IL-10 and INFgamma. Moreover thalidomide plays an important role in inhibition of VEGF and FGF-2 mediated angiogenesis. Although the exact mechanism of action is not fully understood and only limited treatment opinions exist, thalidomide plays a role also in connective diseases and vasculities. Thalidomide has been seen efficacious in the treatment of cutaneous disorders in patients with systemic lupus erythematosus and in mucocutaneous disease in Behcet's disease with a not dose-dependent response, even if it should be restricted to selected patients because of its important side effects.

Anti-TNF-α and risk of infections: the experience in one center.

AIM: In the last years there is an increasing interest for the question of whether patients treated with antitumour necrosis factor-α (TNF-α) agents are at increased risk of infections. We aim to assess the possible role of anti-TNF-α treatment in the increase of the risk of infections in a population of patients affected by rheumatoid arthritis or psoriatic arthritis. METHODS: We analyzed data of patients affected by chronic arthritis treated with anti-TNF-α to investigate the risk of infections. Statistical analysis was done using STATA software. RESULTS: The odds ratio for patients treated with anti-TNF-α who developed infections was 1.61 (CI: 0.88, 2.92, P<0.11). We found an odds ratio of 1.41 (CI: 0.74, 2.68, P<0.29) in patients treated with anti-TNF-α who developed urinary tract infection, and an odds ratio of 2.63 (CI: 0.31, 22.19, P<0.37) in patients treated with anti-TNF-α who developed herpes zoster. DISCUSSION: These results seems to indicate a role of anti-TNF-α treatment in the risk of infection. Nevertheless, our results are not statistically significant probably because the sample sizes are too small and the time of observation among patients is variable. Moreover, other confounding factors may be gender, age and the different degrees of disease activity and comorbidity. In conclusion, limitations in the study size and design preclude definitive conclusions about the question of whether patients treated with anti-TNF-α agents are at increased risk of infections. The performance of additional research are needed to answer this question.

Glucocorticoid induced risk of fractures.

In recent years studies have emphasized the importance of glucocorticoid-induced osteoporosis as the second most common form of osteoporosis after postmenopausal osteoporosis. Several studies have underlined that glucocorticoids are responsible for decreasing bone mineral density and increasing bone fragility, resulting in a large increase in fracture risk. This review wants to provide a background regarding the fracture risk of patients exposed to glucocorticoid treatment, considering the fracture risk as the most appropriate parameter to valuate glucocorticoid-induced osteoporosis. In fact, glucocorticoid treatment induces bone loss and increases fracture risk above all affecting trabecular bone, probably through an alteration in bone turnover and microarchitectural changes responsible for an early increased fracture risk which is primary influenced by dose and duration of treatment, body mass index, age and female gender.

Macrophages in rheumatoid arthritis.

In rheumatoid arthritis (RA) tissue macrophages release growth factors, matrix metalloproteinases, cytokines, and chemokines. While in normal joints there is a balance between proinflammatory and anti-inflammatory cytokines, an imbalance between these inducers and inhibitors of inflammation occurs in RA, where macrophages are responsible for inducing inflammation, matrix destruction and angiogenesis.

Angiogenesis in rheumatoid arthritis.

There is much evidence that rheumatoid arthritis is closely linked to angiogenesis. Important angiogenic mediators have been demonstrated in synovium and tenosynovium of rheumatoid joints. VEGF (Vascular Endothelial Growth Factor), expressed in response to soluble mediators such as cytokines and growth factors and its receptors are the best characterized system in the angiogenesis regulation of rheumatoid joints. Moreover, other angiogenic mediators such as platelet-derived growth factor (PDGF), fibroblast growth factor-2 (FGF-2), epidermal growth factor (EGF), insulin-like growth factor (IGF), hepatocyte growth factor (HGF), transforming growth factor beta (TGF-beta), tumor necrosis factor alpha (TNF-alpha), interleukin-1 (IL-1), IL-6, IL-8, IL-13, IL-15, IL-18, angiogenin, platelet activating factor (PAF), angiopoietin, soluble adhesion molecules, endothelial mediator (endoglin) play an important role in angiogenesis in rheumatoid arthritis. On the other hand, endostatin, thrombospondin-1 and -2 are angiogenic inhibitors in rheumatoid arthritis. The persistence of inflammation in rheumatoid joints is a consequence of an imbalance between these inducers and inhibitors of angiogenesis.