Therapeutic effect of various ginsenosides on rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is an autoimmune disease which causes disability and threatens the health of humans. Therefore, it is of great significance to seek novel effective drugs for RA. It has been reported that various ginsenoside monomers are able to treat RA. However, it is still unclear which ginsenoside is the most effective and has the potential to be developed into an anti-RA drug. METHODS: The ginsenosides, including Rg1, Rg3, Rg5, Rb1, Rh2 and CK, were evaluated and compared for their therapeutic effect on RA. In in vitro cell studies, methotrexate (MTX) and 0.05% dimethyl sulfoxide (DMSO) was set as a positive control group and a negative control group, respectively. LPS-induced RAW264.7 cells and TNF-α-induced HUVEC cells were cultured with MTX, DMSO and six ginsenosides, respectively. Cell proliferation was analyzed by MTT assay and cell apoptosis was carried out by flow cytometry. CIA mice model was developed to evaluate the therapeutic efficacy of ginsenosides. The analysis of histology, immunohistochemistry, flow cytometry and cytokine detections of the joint tissues were performed to elucidate the action mechanisms of ginsenosides. RESULTS: All six ginsenosides showed good therapeutic effect on acute arthritis compared with the negative control group, Ginsenoside CK provided the most effective treatment ability. It could significantly inhibit the proliferation and promote the apoptosis of RAW 264.7 and HUVEC cells, and substantially reduce the swelling, redness, functional impairment of joints and the pathological changes of CIA mice. Meanwhile, CK could increase CD8 + T cell to down-regulate the immune response, decrease the number of activated CD4 + T cell and proinflammatory M1-macrophages, thus resulting in the inhibition of the secretion of proinflammatory cytokine such as TNF-α and IL-6. CONCLUSION: Ginsenoside CK was proved to be a most potential candidate among the tested ginsenosides for the treatment of RA, with a strong anti-inflammation and immune modulating capabilities.

UP1306: A Composition Containing Standardized Extracts of Acacia catechu and Morus alba for Arthritis Management.

Osteoarthritis (OA) is characterized by progressive articular cartilage degradation. Although there have been significant advances in OA management, to date, there are no effective treatment options to modify progression of the disease. We believe these unmet needs could be bridged by nutrients from natural products. Collagen induced arthritis in rats was developed and utilized to evaluate anti-inflammatory and cartilage protection activity of orally administered botanical composition, UP1306 (50 mg/kg) and Methotrexate (75 µg/kg) daily for three weeks. Objective arthritis severity markers, urine, synovial lavage, and serum were collected. At necropsy, the hock joint from each rat was collected for histopathology analysis. Urinary cartilage degradation marker (CTX-II), pro-inflammatory cytokines (tumor necrosis factor α (TNF-α), interleukin-1ß (IL-1ß), and IL-6), and proteases (Matrix Metallopeptidase 3 (MMP3) and 13) were measured. Rats treated with UP1306 showed statistically significant improvements in arthritis severity markers, including uCTX-II (91.4% vs. collagen-induced arthritis (CIA)), serum IL-1ß, TNF-α, and IL-6 levels as well as synovial MMP-13. The histopathology data were also well aligned with the severity score of arthritis for both UP1306 and Methotrexate. UP1306, a botanical composition that contains a standardized blend of extracts from the heartwood of Acacia catechu and the root bark of Morus alba, could potentially be considered as a dietary supplement product for the management of arthritis.

Therapeutic antibody targeting of indoleamine-2,3-dioxygenase (IDO2) inhibits autoimmune arthritis.

Rheumatoid arthritis (RA) is a debilitating inflammatory autoimmune disease with no known cure. Recently, we identified the immunomodulatory enzyme indoleamine-2,3-dioxygenase 2 (IDO2) as an essential mediator of autoreactive B and T cell responses driving RA. However, therapeutically targeting IDO2 has been challenging given the lack of small molecules that specifically inhibit IDO2 without also affecting the closely related IDO1. In this study, we develop a novel monoclonal antibody (mAb)-based approach to therapeutically target IDO2. Treatment with IDO2-specific mAb alleviated arthritis in two independent preclinical arthritis models, reducing autoreactive T and B cell activation and recapitulating the strong anti-arthritic effect of genetic IDO2 deficiency. Mechanistic investigations identified FcγRIIb as necessary for mAb internalization, allowing targeting of an intracellular antigen traditionally considered inaccessible to mAb therapy. Taken together, our results offer preclinical proof of concept for antibody-mediated targeting of IDO2 as a new therapeutic strategy to treat RA and other autoantibody-mediated diseases.

Mechanisms underlying the hyperalgesic responses triggered by joint activation of TLR4.

BACKGROUND: Toll-like receptors (TLRs) including TLR4 and their signal pathways contribute to the pathogenesis of arthritis. Herein, we evaluated the mechanisms underlying the hyperalgesic response caused by TLR4 activation in the tibio-tarsal joint in mice. METHODS: Joint inflammatory hyperalgesia was induced by intra-articular (ia) injection of LPS (lipopolysaccharide- TLR4 agonist) in C57BL/6, TLR4, TLR2, MyD88, TRIF, TNFR1/2 and IL-1R1 knockout (-/-) mice. Joint hyperalgesia was evaluated using an electronic von Frey. Neutrophil recruitment was assessed by MPO activity. Joint levels of cytokines were measured by ELISA. RESULTS: Firstly, it was shown that LPS injected into the joints causes a dose- and time-dependent reduction in the mechanical nociceptive threshold. The TLR4 activation in the joint triggers mechanical hyperalgesia and neutrophil migration, which was abolished in TLR4 -/- and MyD88-/-, but not in TLR2-/- and TRIF-/- mice. Besides, joint administration of LPS increased the release of TNF-α, IL-1ß, and KC/CXCL1, which were reduced in TLR4-/- and MyD88-/-, but not in TRIF-/- mice. In agreement, the LPS-induced joint nociceptive effect was decreased in TNFR1/2-/- and IL-1R1-/- mice or in mice pre-treated with a CXCR1/2 selective antagonist (DF2156A). CONCLUSIONS: These results suggest that TLR4 activation in the joint produces articular hyperalgesia via MyD88 signaling pathway. Moreover, this pathway is involved in the cascade of events of articular hyperalgesia through mechanisms dependent on cytokines and chemokines production. Thus, TLR4/MyD88 signaling pathway inhibitors might be useful for the treatment of inflammatory joint pain.

Effects of the neutrophil elastase inhibitor EL-17 in rat adjuvant-induced arthritis.

OBJECTIVES: Neutrophil elastase (NE), a granule-associated enzyme, participates in connective tissue breakdown and promotes cytokine release and specific receptor activation during various inflammatory diseases like RA. NE is increased in the SF and cartilage of RA patients and represents a target for the development of new therapeutic possibilities. The present research aimed to evaluate the preclinical pharmacological profile of the N-benzoylpyrazole derivative EL-17, a potent and selective NE inhibitor, in a rat model of RA. METHODS: Complete Freund's Adjuvant (CFA) was injected in the tibiotarsal joint and the effect of acute or repeated treatments with EL-17 (1-30 mg/kg by mouth) were evaluated. RESULTS: On day 14 after CFA injection, a single administration of EL-17 significantly reduced CFA-dependent hypersensitivity to mechanical noxious stimuli and the postural unbalance related to spontaneous pain. To evaluate the preventive efficacy, EL-17 was administered daily starting from the day of CFA treatment. Behavioural measurements performed on days 7 and 14 showed a progressive efficacy of EL-17 against hypersensitivity to mechanical noxious and non-noxious stimuli, as well as a decrease of hind limb weight-bearing alterations. Histological evaluation of the tibiotarsal joint (day 14) demonstrated significant prevention of articular derangement after EL-17 (30 mg/kg) treatment. The protective effects of EL-17 directly correlated with a complete reversion of the plasma NE activity increase induced by CFA. CONCLUSIONS: The NE inhibitor EL-17 relieved articular pain after acute administration. Furthermore, repeated treatment reduced the development of hypersensitivity and protected joint tissue, revealing a disease-modifying profile.

Minimal physiologically-based pharmacokinetic (mPBPK) model for a monoclonal antibody against interleukin-6 in mice with collagen-induced arthritis.

Therapeutic monoclonal antibodies (mAb) targeting soluble inflammatory cytokines exert their pharmacological effects in rheumatoid arthritis through binding and neutralizing free cytokines in target tissue sites. Therefore suppression of free cytokines in such sites directly relates to the magnitude of therapeutic response. Although the interrelationships between mAb and cytokines have been examined in the systemic circulation, less is known about the interaction of mAb and cytokines in inflamed joints. In the present study, the interplay between the mAb, CNTO 345, and its target IL-6 in serum as well as ankle joint synovial fluid were characterized in collagen-induced arthritic mice. A minimal physiologically-based pharmacokinetic model with target-mediated drug disposition (TMDD) features in serum and ankle joint synovial fluid was developed for the assessment of the TMDD dynamics of CNTO 345 and IL-6. Our model indicates that TMDD kinetics in ankle joints differ greatly from that in serum. The differences can be attributed to the limited tissue distribution of CNTO 345 in ankle joint synovial fluid, the significant rise of the IL-6 baseline in ankle joint synovial fluid in comparison with serum, and the relative time-scales of elimination rates between CNTO 345, free IL-6 and CNTO 345-IL-6 complex in serum and ankle joint synovial fluid.

Cartilage Repair Using Composites of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells and Hyaluronic Acid Hydrogel in a Minipig Model.

UNLABELLED: The cartilage regeneration potential of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs) with a hyaluronic acid (HA) hydrogel composite has shown remarkable results in rat and rabbit models. The purpose of the present study was to confirm the consistent regenerative potential in a pig model using three different cell lines. A full-thickness chondral injury was intentionally created in the trochlear groove of each knee in 6 minipigs. Three weeks later, an osteochondral defect, 5 mm wide by 10 mm deep, was created, followed by an 8-mm-wide and 5-mm-deep reaming. A mixture (1.5 ml) of hUCB-MSCs (0.5×10(7) cells per milliliter) and 4% HA hydrogel composite was then transplanted into the defect on the right knee. Each cell line was used in two minipigs. The osteochondral defect created in the same manner on the left knee was untreated to act as the control. At 12 weeks postoperatively, the pigs were sacrificed, and the degree of subsequent cartilage regeneration was evaluated by gross and histological analysis. The transplanted knee resulted in superior and more complete hyaline cartilage regeneration compared with the control knee. The cellular characteristics (e.g., cellular proliferation and chondrogenic differentiation capacity) of the hUCB-MSCs influenced the degree of cartilage regeneration potential. This evidence of consistent cartilage regeneration using composites of hUCB-MSCs and HA hydrogel in a large animal model could be a stepping stone to a human clinical trial in the future. SIGNIFICANCE: To date, several studies have investigated the chondrogenic potential of human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs); however, the preclinical studies are still limited in numbers with various results. In parallel, in the past several years, the cartilage regeneration potential of hUCB-MSCs with a hyaluronic acid (HA) hydrogel composite have been investigated and remarkable results in rat and rabbit models have been attained. (These experimental results are currently in preparation for publication.) Before applying the cartilage regeneration technique in a human clinical trial, it seemed necessary to confirm the consistent result in a larger animal model. At 12 weeks postoperatively, the minipigs were sacrificed, and the degree of subsequent cartilage regeneration was evaluated by gross and histological analysis. The transplanted knee resulted in superior and more complete hyaline cartilage regeneration compared with the control knee. This evidence of consistent cartilage regeneration with composites of hUCB-MSCs and HA hydrogel in a large animal model could be a stepping stone to a human clinical trial in the future.

Therapeutic effect of irradiation of magnetic infrared laser on osteoarthritis rat model.

Osteoarthritis (OA) is a degenerative joint disease caused by articular cartilage loss. Many complementary and alternative medicines for OA have been reported so far, but the effectiveness is controversial. Previously, we have shown anti-inflammatory effects of low level laser therapy with static magnetic field, magnetic infrared laser (MIL), in various animal models. Therefore, the beneficial effects were examined in OA rat model. Rats were divided by six groups; no treatment controls of sham and OA model, three MIL treatment groups of OA model at 6.65, 2.66 and 1.33 J cm(-2), and Diclofenac group of OA model with 2 mg kg(-1) diclofenac sodium. The OA control exhibited typical symptoms of OA, but 4-week MIL treatment improved the functional movement of knee joint with reduced edematous changes. In addition, cartilage GAGs were detected more in all MIL treatment groups than OA control. It suggests that 4-week MIL irradiation has dose-dependent anti-inflammatory and chondroprotective effects on OA. Histopathological analyses revealed that MIL treatment inhibits the cartilage degradation and enhances chondrocyte proliferation. The fact that MIL has an additional potential for the cartilage formation and no adverse effects can be regarded as great advantages for OA treatment. These suggest that MIL can be useful for OA treatment.

Matrix metalloproteinase, vitamin A and methylprednisolone effects on experimentally induced amyloid arthropathy.

We evaluated the role of some matrix metalloproteinases (MMPs) in enhancing the effect of vitamin A and the inhibiting effect of methylprednisolone on amyloid arthropathy in brown layer chicks. We used 100 one-day-old Isa brown layer chicks. The chicks were allocated to one of four groups as follows: negative control group (I), vitamin A group (II), positive control group (III) and methylprednisolone group (IV). Amyloid arthropathy was induced by injections of complete Freund's adjuvant into the left intertarsal joints of the chicks. Serum vitamin A and tissue MMP (MMP-1, MMP-2, MMP-9) levels were measured and differences among the groups were investigated. Serum vitamin A rates (µg/dl) were: 63.57 ± 4.10, 47.13 ± 10.62, 53.26 ± 10.79, 98.48 ± 8.20 in groups I, II, III and IV, respectively (p < 0.001). MMP-1, MMP-2 and MMP-9 levels were evaluated in tissues from the chickens with amyloid arthropathy. Methylprednisolone significantly suppressed the release of MMP-1 and MMP-2, and increased the release of MMP-9 in birds with amyloid arthropathy. In addition, vitamin A significantly increased the release of MMP-1, MMP-2 and MMP-9.

Peripheral antinociceptive effect of 2-arachidonoyl-glycerol and its interaction with endomorphin-1 in arthritic rat ankle joints.

1. Both cannabinoid and opioid receptors are localized at the peripheral level, and drugs acting on these receptors may produce antinociception after topical administration; however, the effect of endogenous ligands at these receptors is poorly understood. Our goal was to determine the antinociceptive potency of the endogenous cannabinoid 2-arachidonoyl-glycerol (2-AG), and its interaction with endomorphin-1 (EM1) at joint level in the rat inflammation model. 2. Mechanical hypersensitivity was produced by injection of carrageenan (300 microg/30 microL) into the tibiotarsal joint of the right hind leg. The mechanical threshold was assessed by von Frey filaments. 2-AG (3-200 microg), EM1 (100-300 microg) and their combinations in a fixed-dose ratio (1 : 10) were given into the inflamed joint, and the threshold was determined repeatedly for 105 min after the drug administrations. 3. Both ligands produced dose-dependent anti-hyperalgesia, and the highest doses caused prolonged effects, but they did not influence the degree of oedema and the withdrawal threshold at the non-inflamed side. EM1 had lower potency compared to 2-AG (ED(25): 233 (CI: 198-268) microg and 126 (CI: 88-162) microg, respectively; P < 0.05). The effects of EM1 and 2-AG were prevented by mu-opioid and cannabinoid 1 receptor antagonists, respectively. The ED(25) value for the combination (98 (CI: 80-112) microg) did not differ significantly from the value of 2-AG; however, the largest dose combination produced a significantly higher effect than the ligands by themselves. 4. Our data showed that 2-AG was an effective antinociceptive ligand at joint level, and its combination with EM1 produced long-lasting, effective antinociception.

Hypernociception elicited by tibio-tarsal joint flexion in mice: a novel experimental arthritis model for pharmacological screening.

Mice have been used as animal model to study mechanisms underlying inflammatory and immune diseases. The present study describes a model of joint inflammation-induced hypernociception to discriminate pharmacological tests in mice. A polypropylene tip probe with a large area (4.15 mm2) applied on the plantar surface of the hind paw was used to produce a dorsal flexion of tibio-tarsal joint. Experiments were performed to demonstrate that the probe application did not provoke cutaneous nociception. The decrease in the withdrawal threshold of inflamed joint was used as nociceptive parameter. Administration of zymosan in the tibio-tarsal joint induced a dose and time-dependent hypernociception elicited by articular dorsal flexion movement. Maximal joint hypernociception was detected between 7 and 24 h after zymosan injection, and matched maximal inflammation score as determined by histopathology and neutrophil migration assay. In agreement with the inflammatory hypernociceptive paradigm, flexion-elicited hypernociception induced by zymosan was dose-dependently inhibited by morphine (2-8 mg/kg) and by an effective dose of indomethacin (5 mg/kg). The present study demonstrated that the tibio-tarsal flexion reflex is a behavioral nociceptive model that allows a quantitative evaluation of inflammatory joint hypernociception in mice and its pharmacological modulation.

Prophylactic administration of abatacept prevents disease and bone destruction in a rat model of collagen-induced arthritis.

Abatacept is the first in a new class of agents that selectively modulates T-cell activation by attenuating CD28-mediated co-stimulation. This study examined the effects of abatacept on disease development in a rat model of collagen-induced arthritis (CIA). The rats were treated with either abatacept (1mg/kg) or control IgG beginning at the time of induction of CIA. By day 16, significant paw swelling was observed in IgG-treated control animals that continued to increase, reaching a plateau on day 21. Prophylactic treatment with abatacept completely abrogated paw swelling throughout the study. Histopathology demonstrated a significant reduction in inflammation, cartilage destruction, bone resorption and pannus formation. Abatacept treatment resulted in 90% inhibition of circulating collagen-specific antibodies and decreased the serum expression of many cytokines and chemokines that were upregulated in diseased animals. Immunohistochemical analysis of the ankle joints demonstrated that interleukin-6 production was reduced in the tissues and the numbers of osteoclasts present in the joints were also decreased. Ankle microcomputer tomography (micro-CT) analyses dramatically demonstrated the protective effects of abatacept on bone destruction in these animals. Data presented here demonstrate that prophylactic administration of abatacept significantly inhibits the onset and progression of disease in a rat CIA model, with reductions in inflammation, inflammatory mediators, and bone and joint destruction.

A small molecule alpha 4 beta 1 antagonist prevents development of murine Lyme arthritis without affecting protective immunity.

After infection with Borrelia burgdorferi, humans and mice under certain conditions develop arthritis. Initiation of inflammation is dependent on the migration of innate immune cells to the site of infection, controlled by interactions of a variety of adhesion molecules. In this study, we used the newly synthesized compound S18407, which is a prodrug of the active drug S16197, to analyze the functional importance of alpha4beta1-dependent cell adhesion for the development of arthritis and for the antibacterial immune response. S16197 is shown to interfere specifically with the binding of alpha4beta(1 integrin to its ligands VCAM-1 and fibronectin in vitro. Treatment of B. burgdorferi-infected C3H/HeJ mice with the alpha4beta1 antagonist significantly ameliorated the outcome of clinical arthritis and the influx of neutrophilic granulocytes into ankle joints. Furthermore, local mRNA up-regulation of the proinflammatory mediators IL-1, IL-6, and cyclooxygenase-2 was largely abolished. Neither the synthesis of spirochete-specific Igs nor the development of a Th1-dominated immune response was altered by the treatment. Importantly, the drug also did not interfere with Ab-mediated control of spirochete load in the tissues. These findings demonstrate that the pathogenesis, but not the protective immune response, in Lyme arthritis is dependent on the alpha4beta1-mediated influx of inflammatory cells. The onset of inflammation can be successfully targeted by treatment with S18407.

Anti-inflammatory and analgesic effects of atorvastatin in a rat model of adjuvant-induced arthritis.

Statins exert favorable effects on lipoprotein metabolism but may also possess anti-inflammatory effects. Here, we explored the effects of atorvastatin in a model of adjuvant-induced arthritis in rat. Oral treatment with atorvastatin (1-10 mg/kg) from days 10 to 15 after arthritis induction caused inhibition of the increase in paw volume. Maximal inhibition occurred at a dose of 10 mg/kg. At this dose, atorvastatin markedly ameliorated the histopathological findings of joints obtained from day 16 of arthritic animals. This was mirrored by an effective blockade of neutrophil influx, as assessed by the tissue myeloperoxidase levels. The concentrations of the cytokines interleukin-1beta, interleukin-6 and tumor necrosis factor-alpha and the chemokines CCL5 and CCL2 were significantly decreased in arthritic rats treated with atorvastatin. In contrast, the levels of interleukin-10 were enhanced by the drug treatment. The drug also prevented the hypernociception observed in the inflamed joints. These data clearly illustrate the therapeutic potential of a statin-sensitive pathway in inflammatory arthritis.

Effect of phospholipase A2 inhibitory peptide on inflammatory arthritis in a TNF transgenic mouse model: a time-course ultrastructural study.

We evaluated the therapeutic effect of secretory phospholipase A2 (sPLA2)-inhibitory peptide at a cellular level on joint erosion, cartilage destruction, and synovitis in the human tumor necrosis factor (TNF) transgenic mouse model of arthritis. Tg197 mice (N = 18) or wild-type (N = 10) mice at 4 weeks of age were given intraperitoneal doses (7.5 mg/kg) of a selective sPLA2 inhibitory peptide, P-NT.II, or a scrambled P-NT.II (negative control), three times a week for 4 weeks. Untreated Tg197 mice (N = 10) were included as controls. Pathogenesis was monitored weekly for 4 weeks by use of an arthritis score and histologic examinations. Histopathologic analysis revealed a significant reduction after P-NT.II treatment in synovitis, bone erosion, and cartilage destruction in particular. Conspicuous ultrastructural alterations seen in articular chondrocytes (vacuolated cytoplasm and loss of nuclei) and synoviocytes (disintegrating nuclei and vacuoles, synovial adhesions) of untreated or scrambled-P-NT.II-treated Tg197 mice were absent in the P-NT.II-treated Tg197 group. Histologic scoring and ultrastructural evidence suggest that the chondrocyte appears to be the target cell mainly protected by the peptide during arthritis progression in the TNF transgenic mouse model. This is the first time ultrastructural evaluation of this model has been presented. High levels of circulating sPLA2 detected in untreated Tg197 mice at age 8 weeks of age were reduced to basal levels by the peptide treatment. Attenuation of lipopolysaccharide- and TNF-induced release of prostaglandin E2 from cultured macrophage cells by P-NT.II suggests that the peptide may influence the prostaglandin-mediated inflammatory response in rheumatoid arthritis by limiting the bioavailability of arachidonic acid through sPLA2 inhibition.

Bleomycin-induced arthritis and dermatitis in rats.

We investigated the effect of the antitumor drug bleomycin (BLM) on synovial membrane and periarticular deep dermis in 10-wk-old young adult rats. BLM was found to induce edema, mononuclear cell infiltration and necrosis of the synovial membrane in the knee and tarsal joint, and inflammation in the deep dermis of the plantar hindfoot and digital pulvini in these rats after subcutaneous administration of 20 mg/kg for 3 days. After a 4-wk recovery period, foci of degenerative collagen bundles were observed in the deep dermis of the plantar hindfoot in spite of complete recovery of the lesions in the other dermal and synovial membrane sites. The synovitis was determined to begin with vesiculation of the macrophage-type lining cells, followed by edema and cell infiltration, especially near ligament insertion sites in the knee joint. The early dermal lesion consisted of dissociation of endothelial and subendothelial cells in small blood vessels thought to be postcapillary venules, edema, and monocyte infiltration. The severity of arthritis was greater in young adults than juvenile rats. From these results, BLM was shown to have a toxic effect on synovial lining cells and to induce inflammation in the synovial membrane and periarticular dermis.

Antiinflammatory activity of a Ghanaian antiarthritic herbal preparation: III.

alpha-Amyrin palmitate, present in a Ghanaian antiarthritic herbal preparation of Alstonia boonei, Elaies guineensis and Rauvolfia vomitoria, was synthesised and tested on complete Freund's adjuvant-induced arthritic rats. Administered orally at 56 mg/kg body weight (BW) daily for 8 days from days 11 to 18 post adjuvant (acute) or at 66 mg/kg BW every 48 h for 5 days from days 32 to 40 (chronic), the drug returned the increases in serum hyaluronate and blood granulocytes towards non-arthritic levels and corrected the moderate anaemia of adjuvant arthritis. Histological examinations of the proximal interphalangeal foot joints showed reduced synovial proliferation and invasion of joints and reduced leucocyte infiltration of bone marrow and periarticular tissue in treated rats. The results suggest that alpha-amyrin palmitate contributes to the previously shown antiarthritic effect of the herbal preparation.

Effects of 0.05% chlorhexidine lavage on the tarsocrural joints of horses.

In six horses, a 0.05% solution of chlorhexidine diacetate was used to lavage one tarsocrural joint; the contralateral control joint was lavaged with lactated Ringer's solution. Horses were evaluated daily for lameness. Synovial fluid samples were collected on days 1, 4, and 8 for determination of protein concentration, total and differential leukocyte counts, and mucin clot formation. After death on day 8, synovium and osteochondral samples were collected from the tarsocrural joints for examination of morphology and proteoglycan staining. Lavage with chlorhexidine solution caused lameness that was reduced but still evident at day 8. Synovial protein concentration was significantly increased by chlorhexidine lavage; the greatest increase occurred on day 1. Joint lavage increased synovial leukocyte counts on day 1, primarily by increasing polymorphonuclear (PMN) cell counts. Although total synovial leukocyte counts returned to normal by day 4, PMN cell counts remained elevated through day 8; PMN cell counts for chlorhexidine-lavaged joints were typically twice that of control joints. Chlorhexidine lavage caused synovial ulceration, inflammation, and abundant fibrin accumulation. Consistent differences in proteoglycan staining were not detected between control and chlorhexidine-lavaged joints. Joint lavage with 0.05% chlorhexidine diacetate, the lowest known bactericidal concentration, is not recommended for equine joints.

Pharmacological aspects of arthritis induced by a muramyl dipeptide analogue in rats.

Fourteen consecutive daily subcutaneous injections of 4 mg/kg of the muramyl dipeptide analogue MDP-Lys(L18) into rats caused arthritis characterized by swelling of the tarsal joint, increases in lymphocytes and monocytes in the peripheral blood, and elevated serum immunoglobulin G (IgG). The present study was performed to evaluate the effects of indomethacin, phenylbutazone, dexamethasone, D-penicillamine, aurothioglucose, cyclophosphamide and cyclosporin A on this arthritis. Administration of indomethacin, phenylbutazone or dexamethasone inhibited the development of the tarsal joint swelling, suggesting that prostaglandins may be involved in the pathogenesis of the arthritis. Cyclophosphamide reduced the arthritis, together with decreases in the lymphocyte count and the serum IgG level. Cyclosporin A worsened the arthritis in a dose-dependent manner and increased the neutrophil count without raising the serum IgG level, but inhibited the induction of adjuvant arthritis in rats with Mycobacterium bacilli. MDP-Lys(L18) may therefore induce arthritis differing in mechanism from adjuvant arthritis.