TNF-α antibodies and osteoprotegerin decrease systemic bone loss associated with inflammation through distinct mechanisms in collagen-induced arthritis (original) (raw)
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Osteoprotegerin protects against generalized bone loss in tumor necrosis factor-transgenic mice
Arthritis and Rheumatism, 2003
ObjectiveTo investigate the role of tumor necrosis factor (TNF) in systemic bone loss of chronic inflammatory conditions, such as rheumatoid arthritis (RA), and to address the therapeutic potential of osteoclast blockade.To investigate the role of tumor necrosis factor (TNF) in systemic bone loss of chronic inflammatory conditions, such as rheumatoid arthritis (RA), and to address the therapeutic potential of osteoclast blockade.MethodsWe investigated systemic bone changes in human TNF transgenic (hTNFtg) mice, which spontaneously developed severe inflammatory arthritis.We investigated systemic bone changes in human TNF transgenic (hTNFtg) mice, which spontaneously developed severe inflammatory arthritis.ResultsOsteodensitometry revealed a significant decrease in trabecular bone mineral density (BMD) (−37%) in hTNFtg mice, and histomorphometry revealed a dramatic loss of bone volume (−85%) compared with wild-type controls. Osteoclast-covered bone surface and serum levels of deoxypyridinoline crosslinks were significantly elevated, suggesting increased osteoclast-mediated bone resorption in hTNFtg mice. Osteoprotegerin (OPG) completely blocked TNF-mediated bone loss by increasing BMD (+89%) and bone volume (+647%). Most strikingly, formation of primary spongiosa was dramatically increased (+563%) in hTNFtg mice after OPG treatment. Osteoclast-covered bone surface and serum levels of deoxypyridinoline crosslinks were significantly decreased by OPG, suggesting effective blockade of osteoclast-mediated bone resorption. OPG did not influence levels of hTNF, TNF receptor I (TNFRI), interleukin-1β (IL-1β), and IL-6. However, OPG decreased bone formation parameters (osteoblast-covered bone surface and serum osteocalcin levels), which were elevated in hTNFtg mice. In contrast to OPG, bisphosphonates and anti-TNF treatment did not affect generalized bone loss in hTNFtg mice. Anti-TNF, however, did not affect levels of TNF and TNFRI at the concentrations tested. These data indicate that generalized bone loss due to increased TNF can be blocked by OPG.Osteodensitometry revealed a significant decrease in trabecular bone mineral density (BMD) (−37%) in hTNFtg mice, and histomorphometry revealed a dramatic loss of bone volume (−85%) compared with wild-type controls. Osteoclast-covered bone surface and serum levels of deoxypyridinoline crosslinks were significantly elevated, suggesting increased osteoclast-mediated bone resorption in hTNFtg mice. Osteoprotegerin (OPG) completely blocked TNF-mediated bone loss by increasing BMD (+89%) and bone volume (+647%). Most strikingly, formation of primary spongiosa was dramatically increased (+563%) in hTNFtg mice after OPG treatment. Osteoclast-covered bone surface and serum levels of deoxypyridinoline crosslinks were significantly decreased by OPG, suggesting effective blockade of osteoclast-mediated bone resorption. OPG did not influence levels of hTNF, TNF receptor I (TNFRI), interleukin-1β (IL-1β), and IL-6. However, OPG decreased bone formation parameters (osteoblast-covered bone surface and serum osteocalcin levels), which were elevated in hTNFtg mice. In contrast to OPG, bisphosphonates and anti-TNF treatment did not affect generalized bone loss in hTNFtg mice. Anti-TNF, however, did not affect levels of TNF and TNFRI at the concentrations tested. These data indicate that generalized bone loss due to increased TNF can be blocked by OPG.ConclusionOPG may represent a potent tool for preventing generalized loss of bone mass in chronic inflammatory disorders, especially RA.OPG may represent a potent tool for preventing generalized loss of bone mass in chronic inflammatory disorders, especially RA.
Arthritis and Rheumatism, 2005
ObjectiveTo investigate whether the bone-preserving effects of a RANKL antagonist or a tumor necrosis factor (TNF) antagonist could be further improved by the addition of a bone anabolic agent in inflammatory arthritis.To investigate whether the bone-preserving effects of a RANKL antagonist or a tumor necrosis factor (TNF) antagonist could be further improved by the addition of a bone anabolic agent in inflammatory arthritis.MethodsLewis rats with either adjuvant-induced arthritis (AIA) or collagen-induced arthritis (CIA) were treated for 10 days with PEGylated soluble tumor necrosis factor receptor type I (PEG sTNFRI), interleukin-1 receptor antagonist (IL-1Ra), osteoprotegerin (OPG), parathyroid hormone (PTH), or combinations of these agents starting on day 4 after disease onset. Treatment effects were assessed clinically, radiologically, and histologically, and by morphometry for the extent of paw swelling, bone erosive changes, and synovial inflammation.Lewis rats with either adjuvant-induced arthritis (AIA) or collagen-induced arthritis (CIA) were treated for 10 days with PEGylated soluble tumor necrosis factor receptor type I (PEG sTNFRI), interleukin-1 receptor antagonist (IL-1Ra), osteoprotegerin (OPG), parathyroid hormone (PTH), or combinations of these agents starting on day 4 after disease onset. Treatment effects were assessed clinically, radiologically, and histologically, and by morphometry for the extent of paw swelling, bone erosive changes, and synovial inflammation.ResultsPaw swelling and synovial inflammation were significantly inhibited by PEG sTNFRI in AIA and CIA, and by IL-1Ra in CIA. OPG and PTH had no significant effect on these parameters. Analysis of bone erosion revealed a significant bone-sparing effect of monotherapy with PEG sTNFRI or OPG in both models, whereas IL-1Ra was only effective in CIA. PTH treatment alone did not show a bone-protective effect in either model. With the combination of PEG sTNFRI and PTH, erosion scores (−74% in AIA and −61% in CIA versus controls) were significantly lower than those elicited by PEG sTNFRI alone (−41% and −29%, respectively, versus controls). Similar results were also obtained with the combination of OPG and PTH (−88% in AIA and −73% in CIA, compared with −70% and −55%, respectively, with OPG monotherapy). Coadministration of IL-1Ra and PTH had no synergistic bone-sparing effect. Morphometric analysis revealed that the addition of PTH to PEG sTNFRI or OPG resulted in higher bone volume and higher osteoblast numbers in both AIA and CIA.Paw swelling and synovial inflammation were significantly inhibited by PEG sTNFRI in AIA and CIA, and by IL-1Ra in CIA. OPG and PTH had no significant effect on these parameters. Analysis of bone erosion revealed a significant bone-sparing effect of monotherapy with PEG sTNFRI or OPG in both models, whereas IL-1Ra was only effective in CIA. PTH treatment alone did not show a bone-protective effect in either model. With the combination of PEG sTNFRI and PTH, erosion scores (−74% in AIA and −61% in CIA versus controls) were significantly lower than those elicited by PEG sTNFRI alone (−41% and −29%, respectively, versus controls). Similar results were also obtained with the combination of OPG and PTH (−88% in AIA and −73% in CIA, compared with −70% and −55%, respectively, with OPG monotherapy). Coadministration of IL-1Ra and PTH had no synergistic bone-sparing effect. Morphometric analysis revealed that the addition of PTH to PEG sTNFRI or OPG resulted in higher bone volume and higher osteoblast numbers in both AIA and CIA.ConclusionThe bone-protective effects resulting from RANKL or TNF antagonism can be further improved by the addition of a bone anabolic agent.The bone-protective effects resulting from RANKL or TNF antagonism can be further improved by the addition of a bone anabolic agent.
Biologics: Targets & Therapy, 2008
This review focuses on recent advances in the effect of anti-TNFα therapy on bone metabolism and bone mineral density (BMD) in rheumatoid arthritis (RA). RA is a chronic disease characterized by infl ammation of the synovial joint, cartilage degradation, and subsequent bone destruction. Bone damage is often manifested as erosions, localized juxta-articular bone loss, or generalized bone loss. Thus, blockade of TNFa not only serves to block infl ammation, but also halts the erosive nature of RA and generalized/localized juxta-articular bone loss. Here, we review recent fi ndings showing that anti-TNFa therapy is also effective on halting systemic bone loss. In vitro, TNFa reduces osteoblast activity and increases osteoclast activity through RANKL-RANK pathway. In arthritis animal models, an imbalance between bone formation and resorption is observed. In humans, this coupling of destruction is restored by anti-TNFα therapy early on, but only for a few months. Thus, anti-TNFα prevents the BMD loss in RA patients. In summary, TNFa blockade is not only able to prevent joint destruction, but it is also able to prevent bone loss in RA patients. Future studies are needed to address if TNFa blockers have an effect on bone fractures.
Rheumatology, 2020
Objectives About half of RA patients treated with TNFα inhibitors either do not respond or lose their initial therapeutic response over time. The clinical response is measured by reduction in DAS28, which primarily reflects inflammation. However, other effects of TNFα inhibitors, such as impact on bone erosion, are not assessed by DAS28. We aimed to examine the effect of TNFα inhibitors on bone density, bone biomarkers and cytokine production in responder and non-responder patients and assessed mechanisms of action. Methods BMD in the lumbar spine and femur neck of 117 RA patients was measured by DEXA scan. Bone turnover biomarkers CTX, osteoprotegerin (OPG), osteocalcin and RANKL were measured by ELISA. Levels of 16 cytokines in plasma and in tissue culture supernatants of ex vivo T cells were measured by multiplex assays and ELISA. The effect of treatment with TNFα inhibitors on blood mononuclear cell (MNC) differentiation to osteoclast precursors (OCP) was measured flow cytometry...
Osteoprotegerin Reduces Osteoclast Numbers and Prevents Bone Erosion in Collagen-Induced Arthritis
The American Journal of Pathology, 2002
receptor, RANK, were identified as a critical ligandreceptor pair for osteoclast differentiation and survival. A decoy receptor for RANKL, osteoprotegerin, (OPG) impinges on this system and regulates osteoclast numbers and activity. RANKL is also expressed in collagen-induced arthritis (CIA) in which focal collections of osteoclasts are prominent at sites of bone destruction. To determine the role of RANK signaling events in the effector phase of CIA, we investigated effects of Fc-osteoprotegerin fusion protein (Fc-OPG) in CIA. After induction of CIA in Dark Agouti rats, test animals were treated with or without Fc-OPG (3 mg/ kg/day) subcutaneously for 5 days, beginning at the onset of disease. Paraffin-embedded joints were then analyzed histologically and the adjacent bone assessed by histomorphometry. Osteoclasts were identified using TRAP staining and expression of the mRNA for OPG and RANKL was identified by in situ hybridization. The results indicated that short-term Fc-OPG effectively prevented joint destruction, even though it had no impact on the inflammatory aspects of CIA. In arthritic joints, Fc-OPG depleted osteoclast numbers by over 75% and diminished bone erosion scores by over 60%. Although cartilage loss was also reduced by Fc-OPG, the effects on cartilage were less striking than those on bone. In arthritic joints OPG mRNA was highly expressed and co-localized with RANK ligand, and treatment with Fc-OPG did not affect the expression of endogenous RANKL or OPG mRNA. These data demonstrate that short term Fc-OPG treatment has powerful anti-erosive effects, principally on bone, even though synovitis is not affected. These findings indicate the potential utility of disrupting RANK signaling to preserve skeletal integrity in inflammatory arthritis.
Arthritis and Rheumatism, 2002
ObjectiveTo assess the effect of different dosages and treatment schedules of osteoprotegerin (OPG) on joint preservation in an experimental model of adjuvant-induced arthritis (AIA).To assess the effect of different dosages and treatment schedules of osteoprotegerin (OPG) on joint preservation in an experimental model of adjuvant-induced arthritis (AIA).MethodsMale Lewis rats with AIA (6–8 per group) were treated with a subcutaneous bolus of recombinant human OPG according to one of the following schedules: daily OPG (an efficacious regimen) starting at disease onset (days 9–15), early intervention (days 9–11), delayed intervention (days 13–15), and extended therapy (days 9–22). Inflammation (hind paw swelling) was quantified throughout the clinical course; osteoporosis (bone mineral density [BMD], by quantitative dual x-ray absorptiometry) and morphologic appraisals of inflammation, bone damage, intralesional osteoclasts (by semiquantitative histopathologic scoring), and integrity of the articular cartilage matrix (by retention of toluidine blue stain) were determined in histology sections of arthritic hind paws.Male Lewis rats with AIA (6–8 per group) were treated with a subcutaneous bolus of recombinant human OPG according to one of the following schedules: daily OPG (an efficacious regimen) starting at disease onset (days 9–15), early intervention (days 9–11), delayed intervention (days 13–15), and extended therapy (days 9–22). Inflammation (hind paw swelling) was quantified throughout the clinical course; osteoporosis (bone mineral density [BMD], by quantitative dual x-ray absorptiometry) and morphologic appraisals of inflammation, bone damage, intralesional osteoclasts (by semiquantitative histopathologic scoring), and integrity of the articular cartilage matrix (by retention of toluidine blue stain) were determined in histology sections of arthritic hind paws.ResultsOPG provided dose- and schedule-dependent preservation of BMD and periarticular bone while essentially eliminating intralesional osteoclasts. Dosages ≥2.5 mg/kg/day preserved or enhanced BMD and prevented essentially all erosions. A dosage of 4 mg/kg/day protected joint integrity to a comparable degree when given for 7 (days 9–15) or 14 (days 9–22) consecutive days. At this dosage, early intervention (days 9–11) was twice as effective as delayed intervention (days 13–15) at preventing joint dissolution. Erosions and osteoclast scores were greatly decreased for 26 days (measured from the first treatment) after 7 or 14 daily doses of OPG (4 mg/kg/day). OPG treatment also prevented loss of cartilage matrix proteoglycans, an indirect consequence of protecting the subchondral bone. No OPG dosage or regimen alleviated weight loss, inflammation, or periosteal osteophyte production.OPG provided dose- and schedule-dependent preservation of BMD and periarticular bone while essentially eliminating intralesional osteoclasts. Dosages ≥2.5 mg/kg/day preserved or enhanced BMD and prevented essentially all erosions. A dosage of 4 mg/kg/day protected joint integrity to a comparable degree when given for 7 (days 9–15) or 14 (days 9–22) consecutive days. At this dosage, early intervention (days 9–11) was twice as effective as delayed intervention (days 13–15) at preventing joint dissolution. Erosions and osteoclast scores were greatly decreased for 26 days (measured from the first treatment) after 7 or 14 daily doses of OPG (4 mg/kg/day). OPG treatment also prevented loss of cartilage matrix proteoglycans, an indirect consequence of protecting the subchondral bone. No OPG dosage or regimen alleviated weight loss, inflammation, or periosteal osteophyte production.ConclusionThese data indicate that OPG preserves articular bone and (indirectly) articular cartilage in arthritic joints in a dose- and schedule-dependent manner, halts bone erosion when given at any point during the course of arthritis, produces sustained antierosive activity after a short course, and is most effective when initiated early in the disease.These data indicate that OPG preserves articular bone and (indirectly) articular cartilage in arthritic joints in a dose- and schedule-dependent manner, halts bone erosion when given at any point during the course of arthritis, produces sustained antierosive activity after a short course, and is most effective when initiated early in the disease.