Arthritis In Rabbits Research Articles

Intra-articular treatment of inflammatory arthritis with microsphere formulations of methotrexate: pharmacokinetics and efficacy determination in antigen-induced arthritic rabbits

Methotrexate (MTX) encapsulated microspheres release MTX in the joint in a slow, controlled manner following intra-articular injection in healthy rabbits. The objective of this study was to determine the pharmacokinetics of MTX and to evaluate the efficacy following intra-articular treatment of MTX-loaded microspheres in an antigen-induced inflammatory arthritis rabbit model. Arthritis was induced in both knee joints of rabbits using ovalbumin. Rabbits were intra-articularly treated with MTX solution or MTX microspheres and plasma concentrations of MTX were determined in the first 8 h following intra-articular treatment. Rabbits were killed 14 days following treatment and histological analysis of rabbit joints was conducted to determine efficacy. Arthritis was successfully induced in the joints of rabbits with the observation of histopathological features resembling rheumatoid arthritis. No significant differences were detected between MTX solution and MTX microspheres treated groups compared to phosphate buffered saline (control) animals. MTX microspheres effectively delivered the drug to the intra-articular space. However, a high degree of inter-animal variability, the severity of the disease induced and insufficient length of the observation period were suggested to be possible causes for the lack of therapeutic responses to MTX-loaded microspheres treatment.

Quantitative histological changes of repeated antigen‐induced arthritis in the temporomandibular joints of rabbits treated with intra‐articular corticosteroid

To compare the inflammatory changes of antigen-induced temporomandibular joint (TMJ) arthritis in rabbits by different histological methods and to evaluate the immunomodulatory effect of intra-articular corticosteroid injections histologically. 35 rabbits (10 weeks old) pre-sensibilized with ovalbumin were divided into three groups: a placebo group of five (saline), an arthritis group of 15 (ovalbumin) and a steroid-treated group of 15 (ovalbumin + corticosteroid). Additionally, a group of seven rabbits receiving no sensibilization with ovalbumin and no intra-articular injections served as controls. Histomorphometry of the inflammatory changes in the subsynovial connective tissue (SSCT) of the TMJ included: (i) semi-quantitative (S-Q) scoring of inflammation and synovial proliferation, (ii) thickness measurements and fractional surface and (iii) stereological quantitative assessment of volume and plasma cells in thick sections of the SSCT by an optical fractionator. The histomorphometry showed synovial proliferation in both the arthritis and the steroid groups. The plasma cell count obtained by the optical fractionator was significantly reduced when treating the TMJ with corticosteroids. However, the thickness of the synovial lining and volume of the SSCT as well as S-Q scoring of inflammation showed no difference between the arthritis and the steroid-treated groups. The optical fractionator proved a superior tool compared to S-Q assessments. Counting of plasma cells in the SSCT showed that corticosteroids reduced the inflammation, but did not eliminate it. Semiquantitative scoring of synovial proliferation and inflammation demonstrated low sensitivity regarding changes in immunomodulation in antigen-induced arthritis compared to stereological quantitative estimations using an optical fractionator.

Production of IL-1 and IL-1 receptor antagonist and the pathological significance in lipopolysaccharide-induced arthritis in rabbits.

Injection of lipopolysaccharide (LPS) into rabbit knee joints provoked leucocyte infiltration and loss of proteoglycan (PG) from the cartilage. We investigated the role of IL-1 and IL-1 receptor antagonist (IL-1Ra) and its significance in the pathogenesis of LPS-arthritis. Production of IL-1 beta peaked at 6 h (196.7 +/- 89.4 pg/joint) after injection of 10 ng of LPS, while IL-1Ra peaked at 9 h (34.5 +/- 13.4 ng/joint). The amount of IL-1Ra was 180-200-fold molar excess of IL-1, and a large amount of IL-1Ra was sustained for 1 week. Both IL-1 beta and IL-1Ra were mainly produced by synovial exudate cells. Arthritis was reproduced by rabbit IL-1 beta. LPS-induced leucocyte infiltration was inhibited 70-75% by rabbit IL-1Ra. Loss of PG in LPS-arthritis was prevented by IL-1Ra and also by neutrophil elastase inhibitor, and superoxide dismutase. In leucopenic rabbits, injection of LPS induced neither production of IL-1 beta nor loss of PG. Direct injection of inflammatory exudated cells in leucopenic rabbits reproduced loss of PG, and there was only a partial recovery by IL-1Ra. These results suggest that LPS-initiated IL-1 acts as a key mediator in LPS-arthritis and that endogenous IL-1Ra may suppress a part of IL-1 activity at the site, but its amount was too low for suppression of the produced IL-1. Loss of PG is a sequela of infiltrated leucocytes and leucocyte-derived elastase, and superoxide anion may play a pivotal role in the destruction of cartilage.

Involvement of platelet-activating factor and tumour necrosis factor in the pathogenesis of joint inflammation in rabbits.

We have studied the participation of platelet-activating factor (PAF) in antigen-induced arthritis in rabbits, as well as the possible co-operation between PAF and tumour necrosis factor (TNF) in their ability to induce joint inflammation when injected into the knees of healthy rabbits. The administration of two structurally different PAF receptor antagonists, BN52021 and Alprazolam, from 4 h before the intra-articular injection of ovalbumin in preimmunized rabbits, induced an important reduction in the synovial fluid volume, in the amount of cells infiltrating the articular cavity and the synovial membrane, as well as in the prostaglandin E2 (PGE2) concentration. Furthermore, proteoglycans of the articular cartilage, which were found diminished in animals with non-treated arthritis, were well preserved in rabbits treated with PAF antagonists. All the synovial fluids from joints with arthritis had detectable amounts of PAF. The injection of either TNF or PAF into the joints of normal rabbits induced a mild inflammation. When TNF was administered 1 h before PAF, a synergistic response was noted in the synovial fluid volume, in the accumulation of leucocytes, and in the amount of PGE2. The administration of BN50726, a hetrazepine with a potent PAF-receptor antagonist effect, induced a diminution in those parameters. Our results suggest that PAF may be an early and important mediator of joint damage, and that TNF can amplify the inflammatory response induced by PAF. PAF receptor antagonists could play some role in the treatment of inflammatory joint diseases.

Effect of local viral transfer of interleukin 10 gene on a rabbit arthritis model induced by interleukin 1β

Interleukin 1beta (IL-1beta) is the principal mediator in the pathogenesis of rheumatoid arthritis. Continuous injection of interleukin 1beta (IL-1beta) into the knee articular cavities of animals can induce models that resemble rheumatoid arthritis. The objective of this study was to evaluate the feasibility of local recombinant retrovirus viral interleukin 10 (rRV-vIL-10) gene transfer treatment of a rabbit model of arthritis induced by IL-1beta. An hIL-1beta-induced rabbit rheumatoid arthritis model was established using the MFG-hIL-1beta-neo-HIG-82 cell line, which is capable of continuous secretion of hIL-1beta. After transfecting the rabbit synovial fibroblast cell line (MFG-hIL-1beta-neo-HIG-82) with rRV-vIL-10, G418 was then added to identify the positive clone. The rRV-vIL-10 positive clone was injected into the established rabbit rheumatoid arthritis model through intra-articular injection. Successful gene transfer was determined by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry. The levels of IL-1beta before and after treatment were determined by enzyme- linked immunosorbent assay. Retrovirus vector was an effective vector both to synoviocytes in vitro and synovium tissue in vivo as confirmed by RT-PCR and immunohistochemistry. The rabbit arthritis model treated with rRV-vIL-10 showed a dramatic remission of arthritis and a decline in the level of cytokines such as IL-1beta. Retrovirus-mediated transfection of vIL-10 successfully transferred the gene into rabbit synovium ex vivo and was able to suppress intra-articular inflammation response to IL-1beta.

Therapeutic efficacy of intra-articular adrenomedullin injection in antigen-induced arthritis in rabbits

IntroductionAdrenomedullin is a potent vasodilatory and hypotensive peptide as well as an endogenous immunomodulatory factor with predominantly anti-inflammatory effects. The purpose of the present study was to evaluate the therapeutic effects of adrenomedullin in rabbits with antigen-induced arthritis, an experimental model of rheumatoid arthritis.MethodsFollowing the induction of arthritis in both knee joints by ovalbumin injection into the joint spaces of pre-immunized rabbits, increasing daily doses of adrenomedullin were injected into the knee joint spaces or saline was injected into the contralateral knee joint spaces as the control. For time-course experiments, adrenomedullin and saline were injected into the knee joint spaces daily for 7 days and 20 days. The degree of joint swelling and the histological change in the knee joints injected with adrenomedullin were compared with the control knee joints. Histological evaluation of the infrapatellar fat pads and synovial tissue was performed. TNFα, IL-6, vascular endothelial growth factor and transforming growth factor-beta mRNA levels in the synovial tissue were measured using real-time quantitative PCR.ResultsDaily injections of adrenomedullin into the knee joint spaces of rabbits with antigen-induced arthritis decreased joint swelling. Histological examination revealed that adrenomedullin reduced edematous changes and the infiltration of inflammatory cells in the synovial tissues. Analysis of mRNA levels showed that adrenomedullin significantly reduced TNFα mRNA expression by 21% to 49% in a dose-dependent manner, and dose-dependently increased IL-6 mRNA expression by 45% to 121%.ConclusionsThese results suggest that daily injections of adrenomedullin into the knee joint spaces of rabbits with antigen-induced arthritis ameliorated the inflammatory response in arthritic joints. Adrenomedullin may thus be useful as a treatment for rheumatoid arthritis; however, the effect of adrenomedullin on IL-6 production in the synovial tissue may be an undesirable adverse effect in rheumatoid arthritis therapy.

Quantitative Assessment of Synovial Vascularity Using Contrast-Enhanced Power Doppler Ultrasonography: Correlation with Histologic Findings and MR Imaging Findings in Arthritic Rabbit Knee Model

ObjectiveTo validate contrast-enhanced power Doppler ultrasonography (PD US) for the evaluation of synovial vascularity in an arthritic rabbit knee model in correlation with MR and histological findings.Materials and MethodsPower Doppler ultrasonography was performed for carrageenin-induced arthritic left knee and control right knee of 13 rabbits, first without and then with sonic contrast agent enhancement (Levovist, Schering, Berlin Germany), followed by gadolinium-enhanced MR imaging. Synovial vascularity was quantitatively assessed by calculating the color pixel area in power Doppler sonography using a computer-aided image analysis program and by grading the enhancement on MR images: grade 1, enhancement of knee joint is less than one-third of the area; grade 2, one-third to two-thirds enhancement; and grade 3, more than two-thirds enhancement. Microvessel density (MVD) was measured on slides stained immunohistochemically for CD31 antigen for histological assessment.ResultsThe mean area of color pixels in PD US changed from 4.37 to 16.42 mm2 in the arthritic knee after enhancement (p < 0.05), whereas it changed from 0.77 to 2.31 mm2 in the control knee (p < 0.05). Arthritic knees had greater power Doppler signal than control knees both before and after contrast administration (p < 0.05). The average MVD was 88 in arthritic knees and 46 in control knees. MVDs correlated with color pixel areas of contrast-enhanced power Doppler imaging in arthritic knees. In MR grading of arthritic knees, five were grade 2 and eight were grade 3. MVD and PD US revealed no significant difference between grade 2 and 3 arthritic knees (p > 0.05).ConclusionSonic contrast-enhanced PD US improves the visualization of synovial vascularity and allows quantitative measurement in experimentally induced rabbit arthritic knees.

Targeted delivery of diclofenac sodium via gelatin magnetic microspheres formulated for intra-arterial administration

In the present work, we have attempted to deliver diclofenac sodium to a target site by intra-arterial injection of gelatin magnetic microspheres and subsequent localization using an external magnet. Drug-loaded magnetic microspheres were prepared by emulsification/cross-linking method, characterized by drug loading, magnetite content, size distribution, optical microscopy, scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) analysis, differential scanning calorimetry (DSC), X-ray diffraction (XRD), absence of glutaraldehyde by gas chromatography, and in vitro release studies. The targeting efficiency and the therapeutic efficacy of microspheres were studied in vivo in rabbits. The microspheres showed drug loading of 9.1, 18.7, 24.9% w/w, magnetite content of 27.8–28.9% w/w with an average size range of 25–30.6 μm, depending upon the drug–polymer ratio. They were spherical in nature as evidenced by optical microscopy and SEM. FT-IR, DSC, and XRD studies revealed the absence of drug–polymer interaction. Gas chromatography confirmed the absence of residual glutaraldehyde. The microspheres were able to prolong the drug release over 24–30 days and the application of sonication during in vitro release study has slightly increased the release rate. After intra-arterial administration of microspheres, 77.7% of injected dose was recovered at the target site which revealed good targeting efficiency. The microspheres effectively reduced joint swelling, but lesser extent than the oral diclofenac sodium in high dose, in antigen induced arthritic rabbits without producing gastric ulceration which was observed in rabbits treated with oral diclofenac sodium.

Efficacy of quinupristin/dalfopristin versus vancomycin, alone or in combination with rifampicin, against methicillin-resistant Staphylococcus aureus in a rabbit arthritis model

We compared the efficacy of quinupristin/dalfopristin versus vancomycin, alone or in combination with rifampicin, in a rabbit model of methicillin-resistant Staphylococcus aureus-induced arthritis. Vancomycin, alone or in combination with rifampicin, and quinupristin/dalfopristin + rifampicin were significantly more effective than quinupristin/dalfopristin alone.

Central role of the MEK/ERK MAP kinase pathway in a mouse model of rheumatoid arthritis: Potential proinflammatory mechanisms

To evaluate the role of the MEK/ERK MAP kinase pathway in murine collagen-induced arthritis (CIA) using the selective MEK inhibitor PD184352. We examined the effects of the inhibitor in cytokine-stimulated synovial fibroblasts and in cytokine-induced arthritis in rabbits to investigate its antiinflammatory mechanisms. Murine CIA was used to assess the effects of the selective MEK inhibitor on paw edema, clinical scores, weight loss, histopathologic features, and joint levels of p-ERK. Western blotting and immunohistochemistry techniques were used to assess p-ERK in human and rabbit synovial fibroblasts and synovial tissue from rheumatoid arthritis (RA) patients. Interleukin-1alpha (IL-1alpha)-stimulated stromelysin production in rabbit synovial fibroblasts was assessed by enzyme-linked immunosorbent assay. A rabbit IL-1alpha-induced arthritis model was used to assess the effects of the inhibitor on IL-1alpha-induced MEK activity, stromelysin production, and cartilage degradation. In the CIA model, PD184352 inhibited paw edema and clinical arthritis scores in a dose-dependent manner. Disease-induced weight loss and histopathologic changes were also significantly improved by treatment. Inhibition of disease-induced p-ERK levels in the joints was seen with the inhibitor. Levels of p-ERK in the synovium were higher in RA patients than in normal individuals. PD184352 reduced IL-1alpha-induced p-ERK levels in human RA synovial fibroblasts. The production of p-ERK and stromelysin was also inhibited in IL-1alpha-stimulated rabbit synovial fibroblasts. We observed IL-1alpha-induced p-ERK in the synovial lining, subsynovial vasculature, and articular chondrocytes. IL-1alpha-induced stromelysin production and proteoglycan loss from the articular cartilage were reduced by PD184352. These data demonstrate the inhibition of murine CIA by PD184352, support the hypothesis that antiinflammatory activity contributes to the mechanism of action of the inhibitor, and suggest that a selective inhibitor may effectively treat RA and other inflammatory disorders.

In Vivo Efficacy of Moxifloxacin Compared with Cloxacillin and Vancomycin in a Staphylococcus aureus Rabbit Arthritis Experimental Model

We investigated the efficacies of moxifloxacin, cloxacillin, and vancomycin in a rabbit model of Staphylococcus aureus arthritis. No significant difference between therapeutic regimens was observed after a 7-day treatment. Oral moxifloxacin could be a suitable alternative to standard parenteral therapy for S. aureus arthritis.

Transgene Persistence and Cell Turnover in the Diarthrodial Joint: Implications for Gene Therapy of Chronic Joint Diseases

Local gene therapy for chronic joint diseases requires prolonged transgenic expression, but this has not been reliably achieved in animal models. Using normal and immunocompromised animals, we examined the capacity of various cell types in joint tissues to maintain and express exogenous transgenes after direct intra-articular gene delivery. We found that transgenic expression could persist for the lifetime of the animal but required precise immunological compatibility between the vector, transgene product, and host. It was not dependent on vector integration or promoter origin. We identified two phenotypically distinct sub-populations of genetically modified cells within the joint: (i) transient cells, with a half-life of a few weeks, and (ii) stable cells that reside in the joint tissues indefinitely. Contrary to the prevailing assumption, the transient sub-population was composed almost exclusively of synovial fibroblasts, indicating that the synovium is not an appropriate tissue upon which to base a long-term therapy. Instead, fibroblasts in the ligaments, tendons, and capsule emerged as the primary cell types capable of sustained therapeutic transgene expression. This study sheds new light on the cellular dynamics of articular tissues and suggests that cell turnover and immune reactivity are the key determinants in achieving sustained transgenic expression intra-articularly.

USPIO‐enhanced MR imaging for visualization of synovial hyperperfusion and detection of synovial macrophages: Preliminary results in an experimental model of antigen‐induced arthritis

To evaluate whether ultrasmall superparamagnetic iron particles (USPIO)-enhanced MRI is capable of assessing both synovial perfusion characteristics and the presence of synovial macrophages in a model of antigen-induced arthritis. Unilateral arthritis was induced in six knees of six rabbits. The contralateral knees of the rabbits served as control knees. After onset of arthritis, all 12 knees were scanned prior to and immediately following intravenous administration of USPIO using a multiphase T1-weighted (T1w) fast gradient-echo (FGRE) sequence, and T1w spin-echo (SE), T2-weighted (T2w) FSE, T2*w GRE, and short-tau inversion recovery (STIR) sequences prior to and 24 hours following USPIO administration. SI-vs.-time curves (STCs) and the early enhancement rate during the first 56 seconds (REE(56)) were calculated from SI measurements within the synovial tissue of all knees on dynamic T1w images. MR findings were correlated to histopathology. REE(56) was significantly higher in the synovial tissue of arthritic knees than in the control knees (P < 0.01). Significant T1-, T2-, and T2* effects (P = 0.03-0.04) and multiple synovial vessels were visually detectable within the arthritic synovial tissue 24 hours after administration of USPIO, whereas no signal changes or synovial vessels were seen in the control knees. Histopathology revealed widened synovial blood vessels in the arthritic knees, and confirmed iron uptake by macrophages in the arthritic knees. USPIO-enhanced MRI is capable of both assessing synovial hyperperfusion and detecting macrophages in antigen-induced arthritis in rabbits.

Intra-articular injection of recombinant TRAIL induces synovial apoptosis and reduces inflammation in a rabbit knee model of arthritis

We demonstrated previously that local, intra-articular injection of an adenoviral vector expressing human tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) in a rabbit knee model of inflammatory arthritis stimulated synovial apoptosis and reduced inflammation. To examine whether intra-articular injection of recombinant chimeric human TRAIL protein (rTRAIL) also induces apoptosis of proliferating rabbit synovium and reduces inflammation, we used an experimental rabbit arthritis model of rheumatoid arthritis, induced by intra-articular introduction of allogeneic fibroblasts genetically engineered to secrete human IL-1β. Analysis of synovium isolated from the rabbits treated with intra-articular injection of rTRAIL, relative to saline control, showed areas of extensive acellular debris and large fibrous regions devoid of intact cells, similar to adenoviral mediated TRAIL gene transfer. Extensive apoptosis of the synovial lining was demonstrated using TUNEL analysis of the sections, corresponding to the microscopic findings in hematoxylin and eosin staining. In addition, leukocyte infiltration into the synovial fluid of the inflamed knee joints following rTRAIL treatment was reduced more than 50% compared with the saline control. Analysis of the glycosaminoglycan synthetic rate by cultured cartilage using radiolabeled sulfur and cartilage histology demonstrated that rTRAIL did not adversely affect cartilage metabolism and structure. Analysis of serum alanine aminotransferase showed that intra-articular injection of rTRAIL did not have adverse effects on hepatic function. These results demonstrate that intra-articular injection of rTRAIL could be therapeutic for treating pathologies associated with rheumatoid arthritis.

Microbubble‐enhanced ultrasound exposure promotes uptake of methotrexate into synovial cells and enhanced antiinflammatory effects in the knees of rabbits with antigen‐induced arthritis

To evaluate whether microbubble-enhanced ultrasound (US) treatment promotes the delivery of methotrexate (MTX) into synovial cells and the enhanced antiinflammatory effects of intraarticular MTX therapy in a rabbit arthritis model. Arthritis was induced in both knees of 53 rabbits by immunization with ovalbumin. MTX including a microbubble agent was then injected into the left and right knee joints, and the right knees were exposed to US (MTX+/US+ group), while the left knees were not (MTX+/US- group). The knee joints were evaluated histologically in 7 rabbits at 5 time points up to day 56. Quantitative gene expression of interleukin-1beta (IL-1beta) in synovial tissue was measured on days 7 and 28. Eight rabbits were used for the measurement of MTX concentration in synovial tissue 12 hours after treatment. To evaluate the effect of microbubble-enhanced US treatment in the absence of MTX, only the microbubble agent was injected into the left and right knee joints of 10 rabbits with or without US exposure, and these animals were evaluated histologically on days 7 and 28. The MTX concentration in synovial tissue was significantly higher in the MTX+/US+ group than in the MTX+/US- group. Synovial inflammation was less prominent in the MTX+/US+ group compared with the MTX+/US- group, judging from the results of the histologic evaluation and the gene expression levels of IL-1beta in synovial tissue. It also appeared that microbubble-enhanced US exposure itself did not affect inflammation. Microbubble-enhanced US exposure promoted the uptake of MTX into synovial cells, which resulted in enhancement of the antiinflammatory effects of the intraarticular MTX injection. These results suggest that application of this technique may have clinical benefit.

Therapeutic effects of PG201, an ethanol extract from herbs, through cartilage protection on collagenase-induced arthritis in rabbits

In order to assess the therapeutic effects of PG201 (an ethanol extract from herbs) on osteoarthritis, we investigated whether PG201 could suppress the disease progression of collagenase-induced arthritis (CNIA) in rabbits. The right knees of rabbits were injected intra-articularly with collagenase, and the rabbits were orally treated with distilled water (DW), PG201 (200 mg/kg) or diclofenac (DCF, 10 mg/kg) once a day for 8 weeks. Oral administration of PG201 significantly suppressed the stiffness and bone space narrowing. Cartilage erosion and GAG release ( p < 0.01) were considerably reduced in the knee joints. As well, the mRNA expression of matrix degradation enzymes including MMP-1, -3, and -13 was decreased. On the contrary, the concentrations of TIMP-2 in the synovial fluids were considerably amplified in the PG201 treated group ( p < 0.01), but not in the DCF treated group. The pathologic inflammatory molecules involved in cartilage destruction such as IL-1β, PGE 2, and NO were also diminished by PG201. Taken together, these results indicate that PG201 has therapeutic effects on CNIA through the prominent protection of cartilage. PG201 indeed has great potential as a form of treatment for osteoarthritis.

Scintigraphic imaging of radiolabelled drug delivery systems in rabbits with arthritis

This paper describes a novel approach for designing drug delivery systems for intra-articular (i.a.) treatment of rheumatoid arthritis. Retention of these systems was evaluated by radiolabeling with Tc-99m and gamma scintigraphy in arthritic rabbits. Liposome, niosome, lipogelosome and niogelosome formulations of Diclofenac Sodium (DFNa) have been prepared and drug release properties and in vitro characterisation studies have been carried out. According to characterisation results L1 (DMPC: CHOL: DCP (7:1:2)), L1J1 (DMPC: CHOL: DCP (7:1:2) in C-940 1:1 (w/w)), N (SUR I: CHOL: DCP (7:1:2)) and NJ1 (SUR I: CHOL: DCP (7:1:2) in C-940 1:1 (w/w)) formulations were chosen for the further studies. Retention time of these formulations was evaluated by gamma scintigraphic imaging studies. Rabbits with antigen-induced arthritis were injected intra-articularly with Tc-99m labelled drug delivery systems. Serial scintigraphic images were obtained to investigate the retentions of labelled drug delivery systems in the arthritic joints and choose a suitable formulation for the treatment protocol of arthritis. At the end of the scintigraphic imaging studies it was observed that radiolabelled lipogelosome formulation containing DFNa (L1J1) retained much longer in the experimentally arthritic knee joints of the rabbits. This formulation was used for the treatment protocol of arthritis. Mono articular arthritis was induced in the knee joints of rabbits and it was monitored at regular time intervals by measuring changes in knee joint diameter. Also macroscopic and histopathologic evaluations were performed for further evaluation of arthritis. Great retention of DFNa in the arthritic joint might reduce potential adverse systemic effects of the drug because of local administration into the diseased area. It appeared to be a promising drug delivery system for intra-articular drug delivery.

Intra-articular treatment of arthritis with microsphere formulations of paclitaxel: biocompatibility and efficacy determinations in rabbits.

To assess the biocompatibility of controlled release microspheres prepared from different polymeric biomaterials in various size ranges in rabbit synovial joints and based on these data, design and evaluate the efficacy of an intra-articular, paclitaxel-loaded microspheres formulation in rabbit models of arthritis. Paclitaxel-loaded microspheres of poly(lactide-co-glycolide) (PLGA), poly(L-lactic acid) (PLA) and poly(caprolactone) (PCL) were prepared in different size ranges and inflammatory responses monitored following injection into healthy rabbit joints. The efficacy of 20% paclitaxel-loaded PLA microspheres (35-105 microm size range) injected intra-articularly into antigen and carrageenan induced rabbit models of arthritis was monitored. Polymeric microspheres in the 35-105 microm size range were biocompatible whereas smaller microspheres (1-20 microm) produced an inflammatory response. Efficacy studies showed that injection of 20% paclitaxel-loaded PLA microspheres significantly reduced all measures of inflammation in the antigen arthritis rabbit model. Paclitaxel-loaded PLA microspheres in the 35-105 microm size range, released paclitaxel in a controlled manner over several weeks, and may be a potential formulation for the intra-articular treatment of inflammation in arthritic conditions.

Identification of a synovial fibroblast-specific protein transduction domain for delivery of apoptotic agents to hyperplastic synovium

Synovial hyperplasia, resulting in erosion of cartilage and bone, represents one of the major pathologies associated with rheumatoid arthritis. To develop an approach for efficient delivery of proteins or agents to synovium to induce targeted apoptosis of hyperplastic synovial tissue, we have screened an M13 peptide phage display library for synovial-specific transduction peptides. We identified a novel synovial-targeted transduction peptide, HAP-1, which is able to facilitate specific internalization of protein complexes into human and rabbit synovial cells in culture and rabbit synovial lining in vivo. HAP-1 and a non-tissue-specific cationic protein transduction domain, PTD-5, were fused to an antimicrobial peptide, (KLAK)2, to generate two proapoptotic peptides termed DP2 and DP1, respectively. Administration of these peptides was able to induce apoptosis of rabbit and human synovial cells in culture, with DP2 inducing synovial cell-specific apoptosis. Intra-articular injection of DP1 and DP2 into arthritic rabbit joints with synovial hyperplasia induced extensive apoptosis of the hyperplastic synovium, while reducing the leukocytic infiltration and synovitis. These results suggest that proapoptotic peptides and, in particular, DP2 can be clinically useful for treatment of synovial hyperplasia, as well as inflammation. Moreover, the results demonstrate the feasibility of identifying tissue-specific transduction peptides capable of mediating efficient transduction in vivo.

Therapeutic mechanism of Santeng Dingtong recipe on monosodium urate crystal-induced rabbit arthritis

Objective: To study the therapeutic mechanism of Santeng Dingtong recipe (STDT) on monosodium urate crystal (MSU) induced rabbit arthritis.Methods: Forty-two rabbits were randomly divided into six groups, 7 in each group. Group 1 received 0.9% saline 2.5 ml/kg per day by gastrogavage (ig) for 10 days; Group 2, 3 and 4 received STDT 0.125 g/kg, 1.0 g/kg and 8.0 g/kg per day respectively by ig for 10 days; Group 5 received colchicine 4.5 mg/kg per day by ig for 4 days; and Group 6 was untreated. MSU crystals 10 mg /500 μl containing polymyxin B 10 u/ml was injected into the knee joints of Group 1–5 to make rabbit arthritis models. Leukocytes in synovial lavage fluids was then counted and differentiated; pathological injury of synovial membranes was observed under HE staining; interleukin-1 beta (IL-lβ), tumor necrosis factor alpha (TNFα) and leukotriene B4 (LTB4) content in synovial lavage fluids were determined by ELISA.Results: MSU caused a rapid leukocyte infiltration and increased production of IL-lβ, TNFα and LTB4 2 hrs after intra-articular injection. STDT inhibited neutrophil infiltration in synovial fluids dose-dependently, protected the synovial membrane against pathological injury and reduced the production of IL-lβ, TNFα and LTB4; while colchicine did not decrease the level of TNFα, but significantly inhibited neutrophil infiltration in synovial fluid and reduced the production of IL-11β and LTB4.Conclusion: STDT exerts an anti-inflammatory effect in rabbit model of acute MSU arthritis, its mechanism being probably due to the decrease of IL-1β, TNFα and LTB4 synthesis.