Effect of clodronate on established adjuvant arthritis

Anti-inflammatory activity of aqueous leaf extract of Phyllanthus muellerianus (Kuntze) Exell. and its major constituent, geraniin

ETHNOPHARMACOLOGICAL RELEVANCE

Phyllanthus muellerianus (Kuntze) Exell. which belongs to the Family Euphorbiaceae is a shrub widely distributed in West Africa. It is used traditionally to manage wounds and wound infections, menstrual disorders, fevers, pain and inflammation. Hence to confirm its ethnobotanical uses in managing inflammation, we investigated the anti-inflammatory properties of aqueous leaf extract of P. muellerianus (PLE) and its major isolate, geraniin in experimentally-induced inflammation in rats.

MATERIALS AND METHODS

Carrageenan induced oedema and adjuvant induced arthritis models in rats were used in this study.

RESULTS

In the carrageenan-induced acute inflammation, both 300mg/kg PLE-treated and 10mg/kg geraniin-treated groups significantly reduced the mean maximal swelling attained at 4h to 46.75±4.97% (p<0.01) and 61.65±6.70% (p<0.05), respectively, from the inflamed control response of 122.60±16.39%. In the adjuvant-induced chronic inflammation, both PLE-treated (100 and 300mg/kg) groups and geraniin-treated (10 and 30mg/kg) groups significantly (p<0.001) reduced the total limb swelling over 16 days in the polyarthritic phase compared to the arthritic control. These observations were supported by the radiograph records and the histological investigations of the hind limbs which showed reduced bone damage in both PLE and geraniin-treated rats.

CONCLUSION

The findings may confirm the ethnobotanical use of PLE in the management of inflammatory disorders or conditions and observed anti-inflammatory property of PLE may largely be due to its major constituent, geraniin.

Effect of zoledronate on the expression of vascular endothelial growth factor-a by articular chondrocytes and synovial cells: an in vitro study

Background

The aim of this in vitro study was to determine the effect of zoledronate, which is frequently used to treat osteoporosis, on osteoarthritis by analyzing zoledronate-induced expression of vascular endothelial growth factor-A (VEGF-A) in chondrocytes and synovial cells.

Methods

After chondrocytes and synovial cells were separated and cultured, zoledronate was added, and VEGF-A and pigment epithelium-derived factor (PEDF) expression were quantified by real-time polymerase chain reaction and Western blotting.

Results

There was no significant difference in the expression of VEGF-A mRNA in chondrocytes between the zoledronate group and the control group on the 8th day of culture. The expression of both VEGF-A and PEDF mRNA in synovial cells was significantly decreased in the zoledronate group (P<0.05).

Conclusions

Zoledronate decreases the expression of VEGF-A in synovial cells and may affect the development and progression of osteoarthritis.

Margaritaria discoidea (Euphorbiaceae) stem bark extract attenuates allergy and Freund's adjuvant-induced arthritis in rodents

Background:

Various parts of Margaritaria discoidea find use in traditional medicine in the treatment of pain and oedema. This study evaluated the anti-allergic, anti-inflammatory and anti-arthritic effects of a 70% (v/v) aqueous ethanol extract of the stem bark of Margaritaria discoidea, MDE in rodents.

Materials and Methods:

Systemic anaphylaxis was induced by the injection of compound 48/80 into mice and their survival rate was monitored to evaluate the anti-allergic action of the extract. The effect of MDE assessed on the maximal and total oedema responses in the mouse carrageenan-induced paw oedema was used to evaluate the anti-inflammatory action of the extract while the Freund's adjuvant-induced arthritis model was employed to study the anti-arthritic effects of MDE.

Results:

MDE dose-dependently increased the time for compound 48/80-induced mortality in mice. MDE suppressed the mean maximal swelling and the total paw swellings induced over 6 h in the carrageenan-induced paw oedema when administered either prophylactically or therapeutically. MDE caused a reduction in serum levels of TNFα and IL-6 and significantly suppressed Freund's adjuvant-induced arthritis.

Conclusion:

Margaritaria discoidea suppresses allergy and exhibits anti-inflammatory activity in mice. In addition it attenuates Freund's adjuvant-induced arthritis through a reduction in serum levels of TNFα and IL-6 in rats.

In vitro and in vivo anti-inflammatory effects of 4-methoxy-5- hydroxycanthin-6-one, a natural alkaloid from Picrasma quassioides

In the present study, we evaluated the anti-inflammatory effect of 4-methoxy-5- hydroxycanthin-6-one (CAN), a natural alkaloid isolated from Picrasma quassioides. CAN significantly inhibited the production of NO and the release of TNF-α induced by LPS in macrophage RAW 264.7. Western blot showed that CAN can downregulate the expression of iNOS protein. After oral administration, CAN (3, 9, and 27 mg/kg) reduced the development of carrageenan-induced paw edema and complete Freund's adjuvant (CFA)-induced chronic arthritis in rats. The observed results indicated that pre-treatment with CAN might be an effective therapeutic intervention against inflammatory diseases including chronic arthritis.

The potential of liposomal drug delivery for the treatment of inflammatory arthritis

OBJECTIVE

To review the use of liposomes as a delivery agent in inflammatory arthritis.

METHODS

The literature on liposomes and liposomal drug delivery for the treatment of inflammatory arthritis was reviewed. A PubMed search of articles in the English-language journals from 1965 to 2007 was performed. The index words used were as follows: "rheumatoid arthritis," "liposomes," and "targeted delivery." Papers identified were reviewed, abstracted, and summarized.

RESULTS

Liposomes have the capacity to be used as delivery and targeting agents for the administration of antirheumatic drugs at lower doses with reduced toxicity. In other areas of medicine, the pace of progress has been rapid. In the case of infectious diseases and cancer, liposomal drug delivery has progressed and developed into commercially viable therapeutic options for the treatment of fungal infections (amphotericin B), or metastatic breast cancer and Kaposi sarcoma (doxorubicin, daunorubicin), respectively. In arthritis, the efficacy of prednisolone-loaded long-circulating liposomes is currently being evaluated in a phase II clinical trial. Liposome's application to arthritis is still in its infancy but appears promising as new patents are filed. With improvements in liposomal formulation and targeted synovial delivery, liposomes offer increased therapeutic activity and improvement in the risk-benefit ratio.

CONCLUSION

Recent research into synovial targets and improved liposomal formulations continues to improve our capacity to use liposomes for targeted delivery. With time, this approach has the potential to improve drug delivery and reduce systemic complications.

Extra-skeletal effects of bisphosphonates

Bisphosphonates are pharmacological agents which are currently used both in osteoporosis than in other pathological conditions characterised by an increased bone resorption, such as Paget's disease of bone, malign hypocalcaemia during myeloma, osteolytic bone metastasis and fibrous dysplasia of bone. The most important biological effect of bisphosphonates is the reduction of bone remodelling through the inhibition of osteoclastic activity, but there are many clinical and experimental evidences of extra-skeletal biological effects of bisphosphonates. It has been shown that bisphosphonates exert their effects not only on bone tissue cells, but also on those of the immune system with an "immuno-modulating" effect, influencing the production of pro- and anti-inflammatory cytokines and changing the molecular expression involved in the immune processes and anti-inflammatory response. Although the available data are conflicting, there are several reports concerning the beneficial effects of bisphosphonates in controlling the progression of chronic joint inflammatory diseases, suggesting a wider use for these therapeutic agents in clinical practice.

Differences in osteoclast formation between proximal and distal tibial osteoporosis in rats with adjuvant arthritis: inhibitory effects of bisphosphonates on osteoclasts

Patients with rheumatoid arthritis commonly suffer both systemic and periarticular osteoporosis. Bisphosphonates (BPs) are inhibitors of bone resorption, and several derivatives have been developed for treatment of enhanced bone resorption. We aimed to characterize osteoclast formation in two different sites, the proximal tibial and distal tibial areas, in rats with adjuvant arthritis, and to investigate the impact of amino or non-amino types of bisphosphonate. Adjuvant arthritis was initiated in rats while administering daily injections of either etidronate, a non-amino BP, or alendronate, an amino BP, for 3 weeks. On the day following the last injection, bone mineral density (BMD) was measured in the proximal tibia to assess systemic osteoporosis and in the distal tibia for periarticular osteoporosis using dual-energy X-ray absorptiometry. Subsequently, bone marrow cells from either end of the tibia were collected and incubated for 7 days before staining and counting tartrate-resistant acid phosphatase positive cells. In the rats with adjuvant arthritis, BMD of either end of the tibia was lower than in normal rats. Although etidronate prevented bone mineral loss at both ends, distal loss was significantly less than proximal. In contrast, alendronate significantly inhibited mineral loss primarily in the proximal area. Large osteoclasts, defined as having five or more nuclei, formed preferentially in the proximal tibia, while small osteoclasts with fewer than four nuclei were found mainly distally. The suppressive effect of alendronate was greater on the large osteoclasts, while etidronate had a greater effect on the small osteoclasts. These results show that the size and multinuclearity of osteoclasts and the number of osteoclasts formed are different in the distal and proximal areas of the tibia, and that alendronate and etidronate may suppress different types of osteoclasts as discriminated by the number of nuclei.

Bone loss in inflammatory arthritis: mechanisms and therapeutic approaches with bisphosphonates

The inflammatory process in rheumatoid arthritis provokes intense bone resorption, evidenced as bone erosions, juxta-articular osteopenia and generalized osteoporosis. These types of bone loss share a common pathogenesis, and the role of osteoclasts in focal bone erosion was verified in elegant animal studies. The tumour necrosis factor (TNF) family of cytokines and receptors--specifically TNF-alpha, RANKL, RANK and OPG--are dominant regulators of osteoclastic bone resorption in rheumatoid arthritis. The confirmation of the osteoclast mechanism provides new insight into the structural joint protection afforded by disease-modifying drugs and suggests innovative approaches to limit bone destruction. Emerging treatment strategies for bone disease in rheumatoid arthritis are the use of monoclonal antibodies to neutralize RANKL, and powerful bisphosphonates that target pathogenic osteoclasts.

Animal models of rheumatoid arthritis and their relevance to human disease

Rodent models of rheumatoid arthritis (RA) are useful tools to study the pathogenic process of RA. Among the most widely used models of RA are the streptococcal cell wall (SCW) arthritis model and the collagen-induced arthritis (CIA). Both innate and adaptive immune mechanisms are involved in these rodent models. While no models perfectly duplicate the condition of human RA, they are easily reproducible, well defined and have proven useful for development of new therapies for arthritis, as exemplified by cytokine blockade therapies. Besides SCW and CIA models, there are numerous others including transgenic models such as K/BxN, induced models such as adjuvant-induced and pristane models, and spontaneous models in certain mouse strains, that have been used to help understand some of the underlying mechanisms. This review provides an update and analysis of RA models in mice and rats. The array of models has provided rheumatologists and immunologists a means to understand the multifactorial disease in humans, to identify new drug targets, and to test new therapies.

The protective effects of incadronate on inflammation and joint destruction in established rat adjuvant arthritis

The effects of a new generation bisphosphonate, incadronate, in established adjuvant arthritis rats were evaluated according to the arthritis index, hind paw volume, and radiological and histopathological examinations. Incadronate suppressed the radiological and histopathological changes of hind paws, as well as the joint swelling in a dose-dependent manner. In contrast, the arthritis control rats showed drastic joint inflammation, marked destruction of bone and articular cartilage. The remains of articular cartilage lost Safranin O staining, and were attached with numerous TRAP-positive multinuclear cells. Some of resorption lacunas could be seen at the cartilage matrix nearby the TRAP-positive multinuclear cells. As regards the chondroprotective effects of bisphosphonates, we speculate that it is probably concerned with the inhibition of the chondroclasts. These data indicate that bisphosphonates may be a class of effective agent that can be considered for treatment of various arthritic conditions, including human rheumatoid arthritis.

Incadronate disodium inhibits joint destruction and periarticular bone loss only in the early phase of rat adjuvant-induced arthritis

Destruction of articular cartilage and subchondral bone loss in the affected joints of rat adjuvant arthritis have never been quantified histologically. This study aimed to evaluate the effect of incadronate disodium on joint destruction and periarticular bone loss, using histomorphometric measurements. Seven-week-old female Lewis rats were injected with 0.1 mg of heat-killed Mycobacterium butyricum into the tail base. Immediately after sensitization, vehicle, or incadronate at 10 or 100 microg/kg per day, was administered subcutaneously, three times per week. Hind-paw volume was measured weekly and the animals were killed at 2, 4, 6, and 10 weeks after sensitization. After taking X-rays, decalcified sagittal sections of the ankle joint were prepared and stained with toluidine blue and tartarate-resistant acid phosphatase. Articular cartilage destruction and subchondral bone loss were evaluated histomorphometrically. At 2 weeks after sensitization, no radiographic or histologic changes were observed. However, at 4 weeks, severe articular cartilage destruction and subchondral bone loss were found in the arthritic control group, while these changes were inhibited dose-dependently by incadronate treatment. At 6 and 10 weeks, both the destructive changes and the bone loss had further progressed, and they were not inhibited by incadronate treatment. Incadronate dose-dependently inhibited articular cartilage destruction and subchondral bone loss at 4 weeks after sensitization in this adjuvant arthritis model. However, the suppressive effects of incadronate did not continue until 6 and 10 weeks.

Bisphosphonate Effects in Cancer and Inflammatory Diseases

Bisphosphonates are endogenous pyrophosphate analogs in which a carbon atom replaces the central atom of oxygen. They are indicated in non-neoplastic diseases including osteoporosis, corticosteroid-induced bone loss, Paget disease, and in cancer-related diseases such as neoplastic hypercalcemia, multiple myeloma and bone metastases secondary to breast and prostate cancer. There is now extensive in vitro evidence suggesting a direct antitumor effect of bisphosphonates at different levels of action. Some new in vitro and in vivo studies support the cytostatic effects of bisphosphonates on tumor cells, and the effects on the regulation of cell growth, apoptosis, angiogenesis, cell adhesion, and invasion, with particular attention to biological properties. Well designed clinical trials are necessary to investigate whether the antitumor potential of bisphosphonates may be clinically relevant. On the basis of their effects on macrophages, we may divide bisphosphonates into two distinct categories: aminobisphosphonates, which sensitize macrophages to an inflammatory stimulus inducing an acute-phase response, and non-aminobisphosphonates that can be metabolized into macrophages and that may inhibit the inflammatory response of macrophages. There is evidence of aminobisphosphonate-induced pro-inflammatory response, in particular, related to modifications of the cytokine network. Several in vivo studies have demonstrated an acute-phase reaction after the first administration of aminobisphosphonates, with a significant increase in the main pro-inflammatory cytokines. However, a peculiar aspect concerning the action of non-aminobisphosphonates seems to be an anti-inflammatory activity caused by the inhibition of the release of inflammatory mediators from activated macrophages, such as interleukin (IL)-6, tumor necrosis factor-alpha and IL-1. The inhibition of inflammatory responses is demonstrated in both in vivo and in vitro models. This activity suggests the use of non-aminobisphosphonates in several inflammatory diseases characterized by macrophage-mediated production of acute-phase cytokines, as prevention of erosions in rheumatoid arthritis, and of loosening of joint prostheses, as well as possibly in osteoarthritis, ankylosing spondylitis, myelofibrosis, and hypertrophic pulmonary osteoarthropathy.

Effect of minodronic acid (ONO-5920) on bone mineral density and arthritis in adult rats with collagen-induced arthritis

OBJECTIVE

To study the effect of minodronic acid (ONO-5920) on bone loss and arthritis in rats with collagen-induced arthritis (CIA) treated according to 2 different schedules.

METHODS

Four groups of female Sprague-Dawley rats (7 months old) were studied: rats without CIA treated with vehicle (controls), CIA rats treated with vehicle (CIA-V), CIA rats treated therapeutically with minodronic acid (CIA-T), and CIA rats treated prophylactically with minodronic acid (CIA-P). Minodronic acid was administered orally at 0.2 mg/kg 3 times a week, beginning 2 weeks after initial sensitization in the CIA-T rats and beginning the day after initial sensitization in the CIA-P rats. Bone mineral density (BMD) was measured by peripheral quantitative computed tomography in the proximal metaphysis and diaphysis of the tibia every 2 weeks until week 8, when the rats were killed. The BMD and bone microstructure of the excised femur were evaluated by dual x-ray absorptiometry and microfocal computed tomography, respectively. Histomorphometry of the proximal tibia was also performed.

RESULTS

In CIA-P rats, the incidence of arthritis and the severity of posterior limb swelling were reduced early after sensitization, and the decrease in BMD was prevented throughout the observation period. Bone and joint destruction evaluated by radiography of the foot was reduced in CIA-P rats. The eroded surface was reduced and the microstructure was maintained in CIA-P rats compared with CIA-V rats. The mineral apposition and bone formation rates were not reduced in the CIA-P rats. In CIA-T rats, however, the inflammation was not suppressed and the inhibitory effect on bone loss was smaller than that in CIA-P rats.

CONCLUSION

Minodronic acid suppressed the decrease in BMD and the deterioration of the bone microstructure caused by arthritis. Prophylactic administration of minodronic acid had a preventive effect on arthritis at the early stage, although not throughout the observation period.

The effect of bone remodeling inhibition by zoledronic acid in an animal model of cartilage matrix damage

OBJECTIVE

The purpose of this work was to test the effect of inhibition of bone remodeling, through the use of the bisphosphonate, zoledronic acid, on cartilage matrix damage in an animal model of cartilage matrix damage.

DESIGN

New Zealand white rabbits were divided into four groups for treatment purposes: (1) untreated controls; (2) injected into one knee joint with the cartilage matrix degradation enzyme, chymopapain; (3) injected into one knee joint with chymopapain and also given subcutaneous injections of the bisphosphonate, zoledronic acid, three times per week until sacrifice at either day 28 or 56 post-chymopapain-injection; (4) received only the zoledronic acid injections. At sacrifice, the knee joints were examined grossly and histologically, and biochemically for proteoglycan content. Urine samples were analysed, at intervals, for levels of collagen cross-links which are biochemical markers of cartilage and bone.

RESULTS

Animals receiving both intraarticular chymopapain injections and subcutaneous zoledronic acid injections displayed a significantly lower degree of grossly and histologically detectable cartilage degeneration on the tibial articular surfaces (the articular surface displaying the greatest degree of degeneration) than did animals only receiving the chymopapain injections. In addition, urinary levels of collagen cross-links for bone and cartilage were significantly higher in those animals only receiving chymopapain injections.

CONCLUSION

The bone resorption observed after chymopapain injection into the rabbit knee joint can be inhibited through the use of the bisphosphonate, zoledronic acid. Furthermore, zoledronic acid does not increase the level of cartilage degeneration and appears to provide some level of chondroprotection in this model.

The bisphosphonate zoledronate decreases type II collagen breakdown in patients with Paget's disease of bone

Bisphosphonates have been suggested to be partially chondroprotective in animal models of arthritis. The aim of this study was to assess the short-term effect of the bisphosphonate zoledronate on type II collagen degradation in patients with Paget's disease of bone. Twenty-six patients with active Paget's disease who were a part of a double-blind, placebo-controlled, randomized study comparing the effects of several doses of a single injection of zoledronate, a potent bisphosphonate, were studied. Type II collagen destruction was assessed by urinary levels of type II collagen C-telopeptide (CTX-II) using a new immunoassay. Bone resorption was assessed by measuring the urinary excretion of nonisomerized type I collagen C-telopeptide (alpha CTX-I). Biochemical markers were measured at baseline and 5, 10, 30, and 60 days after injection. At baseline, no significant increase of CTX-II was observed in patients with Paget's disease compared with a group of 27 gender-and age-matched controls, in contrast to the ninefold (p < 0.0001) increase of urinary alpha CTX-I. After a single intravenous injection of zoledronate (200 or 400 microg), urinary CTX-II transiently decreased by a median of 25% 5 days after the injection of zoledronate (p = 0.0023 vs. placebo), then increased to pretreatment levels after 10 days. In contrast, urinary alpha CTX-I decreased within 5 days with a maximal decrease of 51% at day 10 (p < 0.001 vs. baseline and placebo), and levels remained suppressed during the 2 months of the study. Zoledronate not only reduces bone turnover but also directly decreases type II collagen degradation in patients with Paget's disease, suggesting that bisphosphonates may have chondroprotective effects in humans. Measurement of type II collagen breakdown by a new urinary biochemical marker may be useful for in vivo assessment of the effects of drugs that potentially inhibit cartilage destruction.

Up-regulation of prostaglandin E receptor EP2 and EP4 subtypes in rat synovial tissues with adjuvant arthritis

To evaluate the role of the prostaglandin E receptor (EP) subtypes in the development of inflammatory synovitis, we examined EP subtype mRNA distribution in the synovial tissue of rats with adjuvant arthritis and the effect of selective EP agonists on cytokine production by cultured rat synovial cells. We used reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization to measure the level of EP subtype (EP1, EP2, EP3, and EP4) mRNA expression in synovial tissues and cultured synovial cells from the arthritic joints of rats. RT-PCR and ELISA were used to analyse the effects of two selective EP agonists on IL-6 production by cultured rat synovial cells. EP2 and EP4 mRNA expression in inflamed synovial tissues was up-regulated. EP2 and EP4 mRNA were co-expressed in synovial macrophages and fibroblasts in inflamed tissues. EP4 and EP2 agonists both inhibited IL-1-induced IL-6 production. Our results suggest that prostaglandin E2 regulates the functions of synovial macrophages and fibroblasts through EP2 and EP4, which are induced by inflammatory stimuli in rats with adjuvant arthritis.

Contrasting effects of alendronate and clodronate on RAW 264 macrophages: the role of a bisphosphonate metabolite

Clodronate (dichloromethylidene-bisphosphonate), a halogen-containing bisphosphonate, can inhibit the release of cytokines from RAW 264 macrophages and has anti-inflammatory properties in rheumatoid arthritis, whilst amino-containing bisphosphonates such as alendronate (4-amino-1-hydroxybutylidene-bisphosphonate), have pro-inflammatory properties and can cause an acute phase response. The basis for these pharmacological properties is unclear. Recently, it was demonstrated that clodronate is metabolised by certain cell lines in vitro to an analogue of ATP, whereas amino-bisphosphonates are not. We therefore investigated whether clodronate can also be metabolised by RAW 264 macrophages and whether intracellular accumulation of the metabolite (AppCCl2p) could account for the anti-inflammatory properties of clodronate. The effect of alendronate and AppCCl2p on the release of cytokines (IL-1beta, IL-6, and TNFalpha) from RAW 264 cells was compared, and the effect of the bisphosphonates and AppCCl2p on the DNA binding activities of transcription factors, NF-kappaB and AP-1, was investigated. Pretreatment of RAW 264 macrophages with alendronate augmented the LPS-stimulated release of IL-1beta and increased the binding of NF-kappaB to DNA in an electrophoretic mobility shift assay. Without LPS-induction, alendronate did not affect cytokine release or NF-kappaB binding. Clodronate was metabolised by RAW 264 cells to AppCCl2p. Like clodronate, AppCCl2p inhibited the LPS-induced release of cytokines and NO from RAW 264 macrophages. Both clodronate and its metabolite also inhibited the LPS-stimulated binding of NF-kappaB to DNA. In conclusion, these results suggest that the metabolite of clodronate may be responsible for the anti-inflammatory properties of clodronate, and that the contrasting effects of different bisphosphonates on the release of cytokines could be mediated partly through changes in the DNA binding activity of NF-kappaB.

Periarticular bone alterations in chronic antigen-induced arthritis: free and liposome-encapsulated clodronate prevent loss of bone mass in the secondary spongiosa

The long-term effects of acutely administered clodronate (free or liposome-encapsulated) on periarticular bone mass and bone turnover were investigated in chronic antigen-induced arthritis (AIA; day 28). Wistar rats were treated intraperitoneally at 3 h and on days 1, 2, and 7 of AIA, with phosphate-buffered saline (PBS; sham), PBS-containing liposomes, free clodronate, or liposome-encapsulated clodronate (cumulative dose, 3.64 mg/animal). In the primary spongiosa (</=1 mm from the growth plate) sham-treated AIA was associated with a significant decrease (-31%) of trabecular bone volume only; this change was not prevented by any treatment. In the secondary spongiosa (>1.25 mm from the growth plate), sham-treated AIA was associated with: (a) a marked significant decrease in trabecular bone volume (-56%); (b) a significant increase of osteoid-covered surface (+135%); and (c) a numerical increase of resorption surface with osteoclasts (+96%). In the secondary spongiosa, free clodronate completely prevented the loss of periarticular bone mass and selectively normalized the parameters of bone formation (i.e., osteoid-covered surface and osteoid-covered surface with osteoblasts). Clodronate liposomes, in addition to these effects, also significantly suppressed bone resorption (i.e., resorption surface covered with osteoclasts). The effects of clodronate liposomes coincided with in vivo targeting of osteoclasts in primary and secondary spongiosa. Thus, low-dose, acutely administered clodronate, both in free and encapsulated forms, exerts an excellent preventive effect on bone loss in the secondary spongiosa of chronic AIA.

Effect of clodronate on established collagen-induced arthritis in rats

The collagen-induced arthritis model in rats was used to study the effect of disodium clodronate on inflammation and destruction of tarsal, metatarsal, and interphalangeal bones and joints. Female DA rats were immunized with heterologous type II collagen. Fourteen days after immunization, rats with similar scores were assigned to the different experimental groups. They were treated subcutaneously either with saline (controls) or with clodronate at doses of 12.5 and 25 mg/kg/day five times a week for 2 weeks. Clinical signs of arthritis including the severity of paw swelling were assessed weekly. At the time of killing, histological features of the non-decalcified tarsus with tarsal, tarsometatarsal and interphalangeal joints were assessed for inflammatory soft-tissue, articular, and bone changes. All the arthritic control rats developed severe arthritis as shown by the total histological scores of the hindpaw. The treatment with clodronate (25 mg/kg) decreased clinical signs of arthritis, the activity of the collagen-degrading lysosomal enzyme, beta-N-acetylglucosaminidase, in inflamed hindpaw tissue, serum osteocalcin level and serum cross-linked telopeptide of type I collagen level. Histological evaluation indicated moderate arthritis in 29% of the rats and severe arthritis in 71%. The results show that clodronate given therapeutically to arthritic rats, induced with type II collagen, suppresses the intensity of inflammation and bone lesions in the tibiotarsal and tarsometatarsal regions.