Development of a selective matrix metalloproteinase 13 (MMP-13) inhibitor for the treatment of Osteoarthritis

Osteoarthritis (OA) is a chronic disorder that causes damage to the cartilage and surrounding tissues and is characterized by pain, stiffness, and loss of function. Current treatments for OA primarily involve providing only relief of symptoms but does not affect the overall trajectory of the disease. A major goal for treating OA has been to slow down or reverse disease progression. Matrix metalloproteinase-13 (MMP-13) is expressed by chondrocytes and synovial cells in human OA and is thought to play a critical role in cartilage destruction. Herein we report a new, allosteric MMP-13 inhibitor, AQU-019, that has been optimized for potency, metabolic stability, and oral bioavailability through a combination of structure activity relationship (SAR) and deuterium substitution as a potential disease modifying OA drug (DMOAD). The inhibitor was demonstrated to be chondroprotective when injected intraarticular (IA) in the monoiodoacetic acid (MIA) rat model of OA.

Physical inactivity and knee osteoarthritis in guinea pigs

OBJECTIVE

To investigate whether and how a sedentary lifestyle contributes to knee osteoarthritis (OA) incidence and severity.

DESIGN

An experiment was conducted using Hartley guinea pigs, an established idiopathic knee OA model. To simulate a sedentary lifestyle, growing animals (n = 18) were housed for 22 weeks in small cages that restricted their mobility, while another group of animals (n = 17) received daily treadmill exercise to simulate moderate physical activity. After the experiment, histological assessments, biochemical assays, and mechanical testing were conducted to compare tibial articular cartilage structure, strength, and degree of OA degeneration between sedentary and physically active animals. Groups were also compared based on body weight and composition, as well as gut microbial community composition assessed using fecal 16S rRNA gene sequencing.

RESULTS

Prevalence of knee OA was similar between sedentary and physically active animals, but severity of the disease (cartilage lesion depth) was substantially greater in the sedentary group (P = 0.02). In addition, during the experiment, sedentary animals developed cartilage with lower aggrecan quantity (P = 0.03) and accumulated more body weight (P = 0.005) and visceral adiposity (P = 0.007). Groups did not differ greatly, however, in terms of cartilage thickness, collagen quantity, or stiffness, nor in terms of muscle weight, subcutaneous adiposity, or gut microbial community composition.

CONCLUSIONS

Our findings indicate that a sedentary lifestyle promotes the development of knee OA, particularly by enhancing disease severity rather than risk of onset, and this potentially occurs through multiple pathways including by engendering growth of functionally deficient joint tissues and the accumulation of excess body weight and adiposity.

A Synthetic Bottle-brush Polyelectrolyte Reduces Friction and Wear of Intact and Previously Worn Cartilage

A poly(7-oxanorbornene-2-carboxylate) polymer containing pendent triethyleneglycol (TEG) chains of 2.8 MDa ("2.8M TEG") was synthesized and evaluated for long-term lubrication and wear reduction of ex vivo bovine cartilage as well as for synovitis in rats and dogs after intra-articular administration. Bovine cartilage surfaces were tested under torsional friction for 10,080 rotations while immersed in either saline, bovine synovial fluid (BSF), or 2.8M TEG. For each solution, coefficient of friction (μ), changes in surface roughness, and lost cartilage glycosaminoglycan were compared. To directly compare 2.8M TEG and BSF, additional samples were tested sequentially in BSF, BSF, 2.8M TEG, and then BSF. Finally, another set of samples were tested twice in saline to induce surface roughness and then tested in BSF, Synvisc, or 2.8M TEG to determine each treatment's effect on worn cartilage. Next, male Lewis rats were injected in one knee with 2.8M TEG or saline and evaluated for effects on gait, and female beagles were injected with either 2.8M TEG or saline in one knee, and their synovial tissues analyzed for inflammation by H&E staining. Treatment with 2.8M TEG lowers μ, lessens surface roughness, and minimizes glycosaminoglycan loss compared to saline. The 2.8M TEG also reduces μ compared to BSF in pairwise testing and on worn cartilage surfaces. Injection of 2.8M TEG in rat or beagle knees gives comparable effects to treatment with saline, and does not cause significant synovitis.

A synthetic polymeric biolubricant imparts chondroprotection in a rat meniscal tear model

Intra-articular injection of hyaluronic acid (HA) is used to treat osteoarthritis (OA) as a viscosupplement, yet it only provides short-term benefit because HA is cleaved by hyaluronidase and cleared out of the joint after several days. Therefore, we developed a new polymer biolubricant based on poly-oxanorbornane carboxylate to enhance joint lubrication for a prolonged time. Rheological and biotribological studies of the biolubricant reveal viscoelastic properties and coefficient of friction equivalent and superior to that of healthy synovial fluid, respectively. Furthermore, in an ex vivo bovine cartilage plug model, the biolubricant exhibits superior long-term reduction of friction and wear prevention compared to saline and healthy synovial fluid. ISO 10993 biocompatibility tests demonstrate that the biolubricant polymer is non-toxic. In an in vivo rat medial meniscal tear OA model, where the performance of the leading HA viscosupplement (Synvisc-one®) is comparable to the saline control, treatment with the biolubricant affords significant chondroprotection compared to the saline control.

The selective cathepsin K inhibitor MIV-711 attenuates joint pathology in experimental animal models of osteoarthritis

BACKGROUND

MIV-711 is a highly potent and selective cathepsin K inhibitor. The current article summarizes the therapeutic effects of MIV-711 on joint pathology in rabbits subjected to anterior cruciate ligament transection (ACLT), and the prophylactic effects on joint pathology in dogs subjected to partial medial meniscectomy, two surgical models of osteoarthritis (OA).

METHODS

Starting 1 week after surgery, rabbits were dosed daily via oral gavage with either MIV-711 or vehicle (n = 7/group) for 7 weeks. The four treatment groups were: (1) sham + vehicle; (2) ACLT + vehicle; (3) ACLT + MIV-711, 30 µmol/kg and (4) ACLT + MIV-711, 100 µmol/kg. Subchondral bone and articular cartilage structures were assessed by µCT, histomorphometry, and scoring. Dogs subjected to partial medial meniscectomy received either MIV-711 (30 µmol/kg) or vehicle (n = 15/group) via oral gavage once daily, starting 1 day before meniscectomy, for 28 days. Cartilage degradation was assessed at the macroscopic and microscopic levels. The exposures of MIV-711 were assessed in both studies and biomarkers reflecting bone resorption (HP-1 in rabbits, CTX-I in dogs) and cartilage degradation (CTX-II) were measured.

RESULTS

In ACLT rabbits, MIV-711 decreased HP-1 levels by up to 72% (p < 0.001) and CTX-II levels by up to 74% (p < 0.001) compared to ACLT vehicle controls. ACLT surgery significantly reduced the total thickness of the subchondral bone plate and reduced trabecular bone volume in the femur and tibia. These effects were reversed by MIV-711. ACLT resulted in cartilage thickening, which was attenuated by MIV-711. MIV-711 did not affect osteophyte formation or Mankin scores. In dogs, MIV-711 reduced CTX-I and CTX-II levels by 86% (p < 0.001) and 80% (p < 0.001), respectively. Synovial CTX-II levels were reduced by 55-57% (p < 0.001) compared to baseline. MIV-711-treated animals had 25-37% lower macroscopic scores in the femur condyles and 13-33% lower macroscopic scores in the tibial plateaus.

CONCLUSIONS

MIV-711 prevents subchondral bone loss and partially attenuates cartilage pathology in two animal models of OA. These beneficial effects of MIV-711 on joint pathology are observed in conjunction with decreases in bone and cartilage biomarkers that have been shown to be clinically attainable in human. The data support the further development of MIV-711 for the treatment of OA.

Toxicology Evaluation of Drugs Administered via Uncommon Routes: Intranasal, Intraocular, Intrathecal/Intraspinal, and Intra-Articular

As the need for nasal, ocular, spinal, and articular therapeutic compounds increases, toxicology assessments of drugs administered via these routes play an important role in human safety. This symposium outlined the local and systemic evaluation to support safety during the development of these drugs in nonclinical models with some case studies. Discussions included selection of appropriate species for the intended route; conducting nonclinical studies that closely mimic the intended use with adequate duration; functional assessment, if deemed necessary; evaluation of local tissues with special histological staining procedure; and evaluations of safety margins based on local and systemic toxicity.

Analgesic and anti-inflammatory properties of novel, selective, and potent EP4 receptor antagonists

Prostaglandin (PG) E2 is the key driver of inflammation associated with arthritic conditions. Inhibitors of PGE 2 production (NSAIDs and Coxibs) are used to treat these conditions, but carry significant side effect risks due to the inhibition of all prostanoids that play important physiological function. The activities of PGE 2 are transduced through various receptor sub-types. Prostaglandin E2 type 4 receptor (EP4) is associated with the development of inflammation and autoimmunity. We therefore are interested in identifying novel EP4 antagonists to treat the signs and symptoms of arthritis without the potential side effects of PGE 2 modulators such as NSAIDs and Coxibs. Novel EP4 antagonists representing distinct chemical scaffolds were identified using a variety of in vitro functional assays and were shown to be selective and potent. The compounds were shown to be efficacious in animal models of analgesia, inflammation, and arthritis.

Beneficial effects of natural eggshell membrane (NEM) on multiple indices of arthritis in collagen-induced arthritic rats

OBJECTIVES

This study was performed to evaluate the potential efficacy of natural eggshell membrane (NEM) in collagen-induced arthritic rats, a well-established rodent model of inflammation and rheumatoid arthritis.

METHODS

Rats with developing type II collagen-induced arthritis (CIA) were treated once daily by oral gavage on study days -14 to 17 with vehicle or NEM (52 mg/kg body weight). Rats were euthanized on study day 17. Efficacy was assessed by daily ankle caliper measurements, ankle diameter expressed as area under the curve (AUC_d0-17), and histopathologic evaluation of ankles and knees. Serum biomarkers of cartilage function and inflammation [collagen type II C-telopeptide (CTXII), cartilage oligomeric matrix protein (COMP), and alpha-2-macroglobulin (A2M)] were measured by ELISA.

RESULTS

Treatment with NEM resulted in significant beneficial effects on the daily ankle diameter measurements and ankle diameter AUC. Ankle and knee histopathology scores were significantly reduced (36% and 43% reduction of summed individual histopathology scores for ankle and knee, respectively; p < 0.05) toward normal for rats given NEM compared to vehicle controls. The percent reduction of serum CTXII, COMP, and A2M in NEM-treated rats ranged from 30% to 72% (p < 0.05).

CONCLUSIONS

NEM significantly improved multiple aspects of inflammatory arthritis including inflammation, pannus, cartilage damage, bone resorption, and periosteal bone formation. This study provides further support for the use of CTXII, COMP, and A2M as relevant biomarkers that were responsive to NEM.

Nerve growth factor inhibition with tanezumab influences weight-bearing and subsequent cartilage damage in the rat medial meniscal tear model

Objective

To investigate whether the effects of nerve growth factor (NGF) inhibition with tanezumab on rats with medial meniscal tear (MMT) effectively model rapidly progressive osteoarthritis (RPOA) observed in clinical trials.

Methods

Male Lewis rats underwent MMT surgery and were treated weekly with tanezumab (0.1, 1 or 10 mg/kg), isotype control or vehicle for 7, 14 or 28 days. Gait deficiency was measured to assess weight-bearing on the operated limb. Joint damage was assessed via histopathology. A second arm, delayed onset of treatment (starting 3–8 weeks after MMT surgery) was used to control for analgesia early in the disease process. A third arm, mid-tibial amputation, evaluated the dependency of the model on weight-bearing.

Results

Gait deficiency in untreated rats was present 3–7 days after MMT surgery, with a return to normal weight-bearing by days 14–28. Prophylactic treatment with tanezumab prevented gait deficiency and resulted in more severe cartilage damage. When onset of treatment with tanezumab was delayed to 3–8 weeks after MMT surgery, there was no increase in cartilage damage. Mid-tibial amputation completely prevented cartilage damage in untreated MMT rats.

Conclusions

These data suggest that analgesia due to NGF inhibition during the acute injury phase is responsible for increased voluntary weight-bearing and subsequent cartilage damage in the rat MMT model. This model failed to replicate the hypotrophic bone response observed in tanezumab-treated patients with RPOA.

Randomized controlled studies on the efficacy of antiarthritic agents in inhibiting cartilage degeneration and pain associated with progression of osteoarthritis in the rat

Background

As an initial step in the development of a local therapeutic to treat osteoarthritis (OA), a number of agents were tested for their ability to block activation of inflammation through nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB), subchondral bone changes through receptor activator of nuclear factor κB ligand (RANKL)-mediated osteoclastogenesis, and proteolytic degradation through matrix metalloproteinase (MMP)-13 activity. Candidates with low toxicity and predicted efficacy were further examined using either of two widely accepted models of OA joint degeneration in the rat: the monoiodoacetic acid (MIA) model or the medial meniscal tear/medial collateral ligament tear (MMT/MCLT) model.

Methods

Potential therapeutics were assessed for their effects on the activation of nuclear factor (NF)-κB, RANKL-mediated osteoclastogenesis, and MMP-13 activity in vitro using previously established assays. Toxicity was measured using HeLa cells, a synovial cell line, or primary human chondrocytes. Drugs predicted to perform well in vivo were tested either systemically or via intraarticular injection in the MIA or the MMT/MCLT model of OA. Pain behavior was measured by mechanical hyperalgesia using the digital Randall-Selitto test (dRS) or by incapacitance with weight bearing (WB). Joint degeneration was evaluated using micro computed tomography and a comprehensive semiquantitative scoring of cartilage, subchondral bone, and synovial histopathology.

Results

Several agents were effective both in vitro and in vivo. With regard to pain behavior, systemically delivered clonidine was superior in treating MIA-induced changes in WB or dRS, while systemic clonidine, curcumin, tacrolimus, and fluocinolone were all somewhat effective in modifying MMT/MCLT-induced changes in WB. Systemic tacrolimus was the most effective in slowing disease progression as measured by histopathology in the MMT/MCLT model.

Conclusions

All of the agents that demonstrated highest benefit in vivo, excepting clonidine, were found to inhibit MMP-13, NF-κB, and bone matrix remodeling in vitro. The MIA and MMT/MCLT models of OA, previously shown to possess inflammatory characteristics and to display associated pain behavior, were affected to different degrees by the same drugs. Although no therapeutic was remarkable across all measures, the several which showed the most promise in either model merit continued study with alternative dosing and therapeutic strategies.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-016-0921-5) contains supplementary material, which is available to authorized users.

Sustained efficacy of a single intra-articular dose of FX006 in a rat model of repeated localized knee arthritis

OBJECTIVE

To evaluate the efficacy of a single intra-articular (IA) dose of FX006, an extended-release formulation of triamcinolone acetonide (TCA) in poly(lactic-co-glycolic acid) (PLGA) microspheres, on the sequelae of repeated episodes of synovitis.

DESIGN

Three flares of localized synovitis in the right knee of rats were induced over 4 weeks following a single IA injection of various doses of FX006, Kenalog(®) (TCA immediate release or TCA IR), or vehicle. Gait scores were employed to assess analgesic effect, and the joints were evaluated by histology at the end of the study. TCA plasma concentrations and corticosterone levels were monitored through the study.

RESULTS

A single IA dose of 0.28 mg FX006 significantly improved gait scores through all three reactivations. TCA IR at 0.06 mg (providing comparable plasma TCA exposure, 10-fold higher Cmax) demonstrated comparable benefit through the first reactivation only and reduced-to-no efficacy thereafter. Significantly improved histological joint scores were observed with effective doses of FX006 but not with TCA IR. Corticosterone levels were initially decreased following both TCA IR and FX006 treatment, but recovered by Day 14.

CONCLUSIONS

In localized, repeated synovitis in rats, sustained release of TCA following a single IA injection of FX006 significantly prolonged analgesia relative to TCA IR and significantly improved histological scores with no adverse effect on the HPA axis. Since synovitis can contribute to the pathophysiology of multiple joint diseases such as osteoarthritis (OA), RA and gout, FX006 may be an important treatment option for these conditions.

The OARSI histopathology initiative - recommendations for histological assessments of osteoarthritis in the rat

OBJECTIVE

During the development of disease-modifying osteoarthritis (OA) drugs, rat models of OA are frequently used for a first assessment of in vivo efficacy. The most efficacious compound in the rat model may then be tested in a larger animal model before entering human trials. The aim of this study was to describe a histologic scoring system for use in different models of OA in rats that allows standardization and comparison of results obtained by different investigators.

METHODS

The experience of the authors with current scoring systems and the range of lesions observed in rat and human OA studies were considered in recommending this common paradigm for rat histologic scoring. Considerations were made for reproducibility and ease of use for new scorers. Additional scoring paradigms may be employed to further identify specific effects of some disease-modifying drugs.

RESULTS

Although the described scoring system is more complex than the modified Mankin scores, which are recommended for some other species, the reliability study showed that it is easily understood and can be reproducibly used, even by inexperienced scorers.

CONCLUSIONS

The scoring paradigm described here has been found to be sufficiently sensitive to discriminate between treatments and to have high reproducibility. Therefore we recommend its use for evaluation of different rat OA models as well as assessment of disease-modifying effects of treatments in these models.

Protective effects of a cathepsin K inhibitor, SB-553484, in the canine partial medial meniscectomy model of osteoarthritis

OBJECTIVE

Cathepsin K (cat K), a cysteine protease expressed in osteoclasts, chondrocytes and synovial fibroblasts, degrades several bone and cartilage matrix components suggesting its potential role in osteoarthritis (OA). We investigated the effects of SB-553484, an inhibitor of cat K, on lesion severity and biomarkers of collagen degradation in the canine partial medial meniscectomy model.

METHODS

A partial medial meniscectomy was performed in mature female beagle dogs. Animals were dosed orally with vehicle or SB-553484 at 50mg/kg BID for 28 days. The femorotibial joints were evaluated for gross and microscopic histological changes. Biomarkers of collagen degradation were also analyzed.

RESULTS

In dogs treated with SB-553484, subjective gross and calculated degeneration scores decreased significantly by 29% and 46%, respectively. Histopathologic evaluation demonstrated that the summed tibial degeneration score decreased significantly by 21%. Inhibition of tibial cartilage degeneration was significant in zone 1 (32%) and the depth ratio of any tibial matrix change was decreased significantly by 28%. Urinary biomarkers of bone and cartilage degradation were also significantly reduced.

CONCLUSION

Treatment with SB-553484 resulted in mild to moderate beneficial effects on gross and histopathological parameters. Reduction of biomarkers of collagen type I and II degradation indicated a direct effect of the compound on bone and cartilage. These data suggest that the prevention of cartilage degradation by cat K inhibition may represent a valid strategy for pharmacological intervention in OA and that monitoring collagen degradation biomarkers may provide an indication of the protective effects of inhibition of bone and cartilage degradation.

Prevention of cartilage degeneration in a rat model of osteoarthritis by intraarticular treatment with recombinant lubricin

OBJECTIVE

Lubricin, also referred to as superficial zone protein and PRG4, is a synovial glycoprotein that supplies a friction-resistant, antiadhesive coating to the surfaces of articular cartilage, thereby protecting against arthritis-associated tissue wear and degradation. This study was undertaken to generate and characterize a novel recombinant lubricin protein construct, LUB:1, and to evaluate its therapeutic efficacy following intraarticular delivery in a rat model of osteoarthritis (OA).

METHODS

Binding and localization of LUB:1 to cartilage surfaces was assessed by immunohistochemistry. The cartilage-lubricating properties of LUB:1 were determined using a custom friction testing apparatus. A cell-binding assay was performed to quantify the ability of LUB:1 to prevent cell adhesion. Efficacy studies were conducted in a rat meniscal tear model of OA. One week after the surgical induction of OA, LUB:1 or phosphate buffered saline vehicle was administered by intraarticular injection for 4 weeks, with dosing intervals of either once per week or 3 times per week. OA pathology scores were determined by histologic analysis.

RESULTS

LUB:1 was shown to bind effectively to cartilage surfaces, and facilitated both cartilage boundary lubrication and inhibition of synovial cell adhesion. Treatment of rat knee joints with LUB:1 resulted in significant disease-modifying, chondroprotective effects during the progression of OA, by markedly reducing cartilage degeneration and structural damage.

CONCLUSION

Our findings demonstrate the potential use of recombinant lubricin molecules in novel biotherapeutic approaches to the treatment of OA and associated cartilage abnormalities.

Exacerbation of collagen-induced arthritis by oligoclonal, IL-17-producing gamma delta T cells

Murine gammadelta T cell subsets, defined by their Vgamma chain usage, have been shown in various disease models to have distinct functional roles. In this study, we examined the responses of the two main peripheral gammadelta T cell subsets, Vgamma1(+) and Vgamma4(+) cells, during collagen-induced arthritis (CIA), a mouse model that shares many hallmarks with human rheumatoid arthritis. We found that whereas both subsets increased in number, only the Vgamma4(+) cells became activated. Surprisingly, these Vgamma4(+) cells appeared to be Ag selected, based on preferential Vgamma4/Vdelta4 pairing and very limited TCR junctions. Furthermore, in both the draining lymph node and the joints, the vast majority of the Vgamma4/Vdelta4(+) cells produced IL-17, a cytokine that appears to be key in the development of CIA. In fact, the number of IL-17-producing Vgamma4(+) gammadelta T cells in the draining lymph nodes was found to be equivalent to the number of CD4(+)alphabeta(+) Th-17 cells. When mice were depleted of Vgamma4(+) cells, clinical disease scores were significantly reduced and the incidence of disease was lowered. A decrease in total IgG and IgG2a anti-collagen Abs was also seen. These results suggest that Vgamma4/Vdelta4(+) gammadelta T cells exacerbate CIA through their production of IL-17.

Vγ4+ γδ T cells act as TH-17 cells in a mouse model of collagen-induced arthritis (130.39)

We have examined two γδ T cells subsets, Vγ1 and Vγ4, in collagen-induced arthritis. The Vγ4+ subset increases expression of CD44 and loses expression of CD62L after each collagen/CFA injection, suggesting this subset is activated during the disease process. The Vγ1+ subset increases in overall numbers but the surface markers remain unchanged. We depleted the γδ subsets to examine their roles in the disease process. Disease scores and histology revealed a significant reduction in both the severity and incidence of arthritis in mice depleted of Vγ4+cells. Depletion of the Vγ1+ subset had no significant effect. We also noted a significant decrease in the levels of total IgG and IgG2a anti-collagen antibodies in mice that were depleted of Vγ4+ cells. Next, we used intracellular cytokine staining to identify which cytokines were being made by the Vγ4+ cells during the height of their activation. Surprisingly, over 60% of the Vγ4+ cells produce IL-17. In fact, as a population, the Vγ4+ cells contain as many or more IL-17 producers as do all CD4+ αβ T cells together. Thus, depletion of the Vγ4+ subset may reduce IL-17 levels, leading to less severe disease in this model. Finally, preliminary data indicate that the Th-17 Vγ4+ cells in this disease model are preferentially paired with one delta chain and express very limited junctional sequences.

This work is supported by an Arthritis Investigator award from the Arthritis Foundation.

Culture-independent analysis of indomethacin-induced alterations in the rat gastrointestinal microbiota

Nonsteroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed for a variety of inflammatory conditions; however, the benefits of this class of drugs are accompanied by deleterious side effects, most commonly gastric irritation and ulceration. NSAID-induced ulceration is thought to be exacerbated by intestinal microbiota, but previous studies have not identified specific microbes that contribute to these adverse effects. In this study, we conducted a culture-independent analysis of approximately 1,400 bacterial small-subunit rRNA genes associated with the small intestines and mesenteric lymph nodes of rats treated with the NSAID indomethacin. This is the first molecular analysis of the microbiota of the rat small intestine. A comparison of clone libraries and species-specific quantitative PCR results from rats treated with indomethacin and untreated rats revealed that organisms closely related to Enterococcus faecalis were heavily enriched in the small intestine and mesenteric lymph nodes of the treated rats. These data suggest that treatment of NSAID-induced ulceration may be facilitated by addressing the microbiological imbalances.

Soluble human p55 and p75 tumor necrosis factor receptors reverse spontaneous arthritis in transgenic mice expressing transmembrane tumor necrosis factor α

OBJECTIVE

The roles of the transmembrane and secreted forms of tumor necrosis factor alpha (TNFalpha) in rheumatoid arthritis (RA) remain unclear. Agents used to inhibit TNFalpha have shown varying efficacy in RA patients, suggesting that anti-TNFalpha agents possess dissimilar mechanisms of action, including the ability to neutralize transmembrane (tmTNFalpha) and secreted TNFalpha. In this study, TNFalpha-knockout (TNFalpha-KO) mice that were genetically altered to express elevated levels of tmTNFalpha were constructed to further understand the roles of the 17-kd secreted, trimeric, and 26-kd transmembrane forms of TNFalpha.

METHODS

A speed-congenic mating scheme was used to generate 3 unique strains of mice: 1) transgenic tmTgA86 mice overexpressing 26-kd tmTNFalpha and also secreting 17-kd trimeric TNFalpha (tmTNFalpha-transgenic), 2) TNFalpha-/- mice (TNFalpha-KO), and 3) transgenic mice overexpressing tmTNFalpha backcrossed to TNFalpha-KO mice (tmTNFalpha-transgenic/TNFalpha-KO). Mice were treated with phosphate buffered saline (as vehicle control), dexamethasone (as positive control), or modified recombinant human soluble TNF receptor (sTNFR) p55 or p75, and were assessed clinically and histopathologically for signs of inflammation and development of arthritis.

RESULTS

The tmTNFalpha-transgenic/TNFalpha-KO mice were born with crinkled tails and spinal deformities similar to those in ankylosing spondylitis. By 2-4 weeks, these mice developed symmetric inflammatory arthritis, characterized by tissue swelling, pannus formation, and bone deformities. The tmTNFalpha-transgenic mice also developed spontaneous-onset arthritis, but at a slower rate (100% incidence by 10-12 weeks). Clinical and histologic progression of arthritis in the tmTNFalpha-transgenic/TNFalpha-KO mice was reduced by treatment with dexamethasone or with the p55 or p75 sTNFR (69% and 63% reduction in total histologic score, respectively).

CONCLUSION

These data show that arthritis is sufficiently initiated and maintained in tmTNFalpha-transgenic/TNFalpha-KO mice, and that it can be neutralized by recombinant human p55 or p75 sTNFR, resulting in amelioration of the biologic and subsequent histologic destructive effects of tmTNFalpha.

Fibroblast growth factor-18 stimulates chondrogenesis and cartilage repair in a rat model of injury-induced osteoarthritis

OBJECTIVE

Osteoarthritis (OA) is the most common form of arthritis and a primary cause of disability, however, there are no treatments that can slow disease progression or repair damaged joint cartilage. Fibroblast growth factor-18 (FGF18) has been reported to have significant anabolic effects on cartilage. We therefore examined its effects on repair of cartilage damage in a rat meniscal tear model of OA.

DESIGN

Surgical damage to the meniscus in rats leads to joint instability and significant damage to the articular cartilage at 3 weeks post-surgery. At this time, animals received bi-weekly intra-articular injections of FGF18 for 3 weeks, and the knee joints were then harvested for histologic examination.

RESULTS

FGF18-induced dose-dependent increases in cartilage thickness of the tibial plateau, due to new cartilage formation at the articular surface and the joint periphery. The generation of new cartilage resulted in significant reductions in cartilage degeneration scores. The highest dose of FGF18 also induced an increase in chondrophyte size and increased remodeling of the subchondral bone.

CONCLUSIONS

The results of this study demonstrate that FGF18 can stimulate repair of damaged cartilage in a setting of rapidly progressive OA in rats.

Evaluation of changes in vertical ground reaction forces as indicators of meniscal damage after transection of the cranial cruciate ligament in dogs

OBJECTIVE

To determine whether decreases in peak vertical force of the hind limb after transection of the cranial cruciate ligament (CrCL) would be indicative of medial meniscal damage in dogs.

ANIMALS

39 purpose-bred adult male Walker Hounds.

PROCEDURE

The right CrCL was transected arthroscopically. Force plate measurements of the right hind limb were made prior to and 2, 4, 10, and 18 weeks after transection of the CrCL. Only dogs with > or =10% decreases in peak vertical force after week 2 were considered to have potential meniscal damage. Dogs that did not have > or =10% decreases in peak vertical force at any time point after week 2 were assigned to group 1. Group 2 dogs had > or =10% decreases in peak vertical force from weeks 2 to 4 only. Group 3 and 4 dogs had > or =10% decreases in peak vertical force from weeks 4 to 10 only or from weeks 10 to 18 only, respectively. Damage to menisci and articular cartilage was graded at week 18, and grades for groups 2 to 4 were compared with those of group 1.

RESULTS

The percentage change in peak vertical force and impulse area was significantly different in groups 2 (n = 4), 3 (4), and 4 (4) at the end of each measurement period (weeks 4, 10, and 18, respectively) than in group 1 (27). The meniscal grade for groups 2 to 4 was significantly higher than for group 1. A > or =10% decrease in peak vertical force had sensitivity of 52% and accuracy of 72% for identifying dogs with moderate to severe medial meniscal damage.

CONCLUSIONS AND CLINICAL RELEVANCE

In dogs with transected or ruptured CrCLs, force plate analysis can detect acute exacerbation of lameness, which may be the result of secondary meniscal damage, and provide an objective noninvasive technique that delineates the temporal pattern of medial meniscal injury.

Enhanced circulating half-life and hematopoietic properties of a human granulocyte colony-stimulating factor/immunoglobulin fusion protein

OBJECTIVE

The aim of this study was to determine whether fusion proteins comprising human granulocyte colony-stimulating factor (G-CSF) joined to human immunoglobulin G1 and G4 (IgG1 and IgG4) Fc and C(H) domains are biologically active and have improved pharmacokinetic and hematopoietic properties in vivo.

MATERIAL AND METHODS

Chimeric genes encoding human G-CSF fused to the N-termini of the Fc and C(H) domains of human IgG1 and IgG4 were constructed and used to transfect monkey COS cells. The fusion proteins were purified from the conditioned media by protein A affinity chromatography. Bioactivities of the proteins were measured in a G-CSF-dependent in vitro bioassay. Pharmacokinetic and granulopoietic properties of the G-CSF/IgG1-Fc fusion protein were measured in normal rats.

RESULTS

The G-CSF/IgG-Fc and G-CSF/IgG-C(H) fusion proteins were secreted from transfected COS cells primarily as disulfide-linked homodimers. On a molar basis, the purified G-CSF/IgG-Fc fusion proteins were as active as G-CSF in in vitro bioassays, whereas bioactivities of the purified G-CSF/IgG-C(H) fusion proteins were decreased 3- to 4-fold. The G-CSF/IgG1-Fc fusion protein displayed a slower plasma clearance rate and stimulated greater and longer lasting increases in circulating neutrophils and white blood cells than G-CSF following intravenous and subcutaneous administration to rats.

CONCLUSION

Fusion of G-CSF to human IgG domains results in homodimeric fusion proteins possessing high in vitro bioactivities, long circulating half-lives, and enhanced hematopoietic properties in vivo.

Design of PEGylated soluble tumor necrosis factor receptor type I (PEG sTNF-RI) for chronic inflammatory diseases

A recombinant C-terminal truncated form of the human soluble tumor necrosis factor receptor type I (sTNF-RI) was produced in E. coli. This soluble receptor contains the first 2.6 of the 4 domains of the intact sTNF-RI molecule. A monoPEGylated form of this molecule was produced using a 30 kD methoxyPEG aldehyde with approximately 85% selectivity for the N-terminal amino group. This molecule was shown to be less immunogenic in primates than the full length (4.0 domain) molecule or other versions of sTNF-RI which were either PEGylated at different sites or with different molecular weight PEGs. The 30 kD PEG also has a longer serum half-life to the molecule than lower molecular weight PEGs. This molecule markedly blunts the inflammatory response in a number of rheumatoid arthritis animal models. In addition, phase I/II and early phase II data in humans indicate that PEG sTNF-RI is non-immunogenic and that weekly dosing with this drug can reduce the number of tender and swollen joints in rheumatoid arthritis patients. PEG sTNF-RI has comparable American College of Rheumatology (ACR) efficacy scores as other anti-TNF molecules currently used to treat rheumatoid arthritic patients.

Animal models of osteoarthritis in an era of molecular biology

Animal models of osteoarthritis (OA) are used to study the pathogenesis of cartilage degeneration and to evaluate potential anti-arthritic drugs for clinical use. In general, these models fall into 2 categories, spontaneous and induced (surgical instability or genetic manipulation). Animal models of naturally occurring OA occur in knee joints of guinea pigs, mice and Syrian hamsters. Commonly utilized surgical instability models include medial meniscal tear in guinea pigs and rats, medial or lateral partial meniscectomy in rabbits, medial partial or total meniscectomy or anterior cruciate transection in dogs. Transgenic models have been developed in mice. These models all have potential use in the study of molecular mechanisms associated with OA development via use of immunohistochemistry, biochemistry and molecular probes to identify altered matrix molecules at different stages in disease progression. Testing of specific types of inhibitors developed through evaluation of matrix changes in the disease process will ultimately help identify key processes which initiate and perpetuate the disease and will lead to discovery of new disease modifying pharmaceutical agents for OA patients. This paper will focus on the discussion of several models which are likely to be useful in the molecular dissection of processes involved in cartilage degeneration.

Induction of osteoarthritis in the rat by surgical tear of the meniscus: Inhibition of joint damage by a matrix metalloproteinase inhibitor

OBJECTIVE

Characterize a model of osteoarthritis (OA) induced by a surgically transecting the medial collateral ligament and meniscus. Evaluate the effectiveness of a matrix metalloproteinase (MMP) inhibitor in this model.

METHODS

The medial collateral ligament of the right knee of rats was transected and a single full thickness cut was made through meniscus. Rats were sacrificed at various times after the surgery to assess the severity of gross cartilage damage using an image analyser and microscopically by histology. The effect of an MMP inhibitor in this model was assessed by administering compound twice daily for the 21 days and evaluating gross and histological joint damage at day 21. The in vitro potency of the MMP inhibitor (MMPI) against a panel of human recombinant MMPs was assessed kinetically using a quenched fluorescent substrate.

RESULTS

Surgical transection of the medial collateral ligament and meniscus resulted in a time dependent increase in the severity of the cartilage lesion (depth) as measured histologically but only a slight increase in the area of the lesion as assessed grossly by image analysis. Administration of a MMPI orally twice daily (b.i.d.) at 25mg/kg to rats in the meniscal tear model resulted in significant inhibition of cartilage degradation and osteophyte formation (total joint score) of 39+/-7% (mean+/-S.E.M., from four separate experiments).

CONCLUSION

These results demonstrate that MMP inhibition is effective in reducing the joint damage that occurs in the meniscal tear model of OA and support a potential therapeutic role for MMP inhibition in the treatment of human OA.

Animal models of osteoarthritis

Animal models of osteoarthritis are used to study the pathogenesis of cartilage degeneration and to evaluate potential antiarthritic drugs for clinical use. Animal models of naturally occurring osteoarthritis (OA) occur in knee joints of guinea pigs, mice and other laboratory animal species. Transgenic models have been developed in mice. Commonly utilized surgical instability models include medial meniscal tear in guinea pigs and rats, medial or lateral partial meniscectomy in rabbits, medial partial or total meniscectomy or anterior cruciate transection in dogs. Additional models of cartilage degeneration can be induced by intra-articular iodoacetate injection or by administration of oral or parenteral quinolone antibiotics. None of these models have a proven track record of predicting efficacy in human disease since there are no agents that have been proven to provide anything other than symptomatic relief in human OA. However, agents that are active in these models are currently in clinical trials. Methodologies, gross and histopathologic features and comparisons to human disease will be discussed for the various models.

Combination benefit of treatment with the cytokine inhibitors interleukin-1 receptor antagonist and PEGylated soluble tumor necrosis factor receptor type I in animal models of rheumatoid arthritis

OBJECTIVE

To determine the potential for additive or synergistic effects of combination therapy with the recombinant anticytokine agents interleukin-1 receptor antagonist (IL-1Ra) and PEGylated soluble tumor necrosis factor receptor type I (PEG sTNFRI) in established type H collagen-induced arthritis (CIA) and developing adjuvant-induced arthritis (AIA) in rats.

METHODS

Rats with established CIA or developing AIA were treated with various doses of IL-1Ra in a slow-release hyaluronic acid vehicle or with PEG sTNFRI, either alone or in combination with the IL-1Ra. The effects of treatment were monitored by sequential caliper measurements of the ankle joints or hind paw volumes, final paw weights, and histologic evaluation with particular emphasis on bone and cartilage lesions.

RESULTS

Combination therapy with IL-1Ra and PEG sTNFRI in rats with CIA resulted in an additive effect on clinical and histologic parameters when moderately to highly efficacious doses of each protein were administered. Greater-than-additive effects were seen when an inactive dose of IL-1Ra was given in combination with moderately to minimally active doses of PEG sTNFRI. Plasma levels associated with the latter effect (for both proteins) were similar to those seen in rheumatoid arthritis (RA) patients in clinical trials with these agents. Combination therapy in the AIA model generally resulted in additive effects, but some parameters showed a greater-than-additive benefit.

CONCLUSION

The results provide preclinical support for the hypothesis that IL-1Ra administered in combination with PEG sTNFRI might provide substantially more clinical benefit to RA patients than either agent alone at blood levels that are currently achievable in patients.

Pharmacologic actions of the second generation leukotriene B4 receptor antagonist LY29311: in vivo pulmonary studies

We examined the in vivo actions of LY293111 sodium (2-[2-propyl-3-[3-[2-ethyl-4-(4-fluorophenyl)-5-hydroxyphenoxy]pro poxy]phenoxy] benzoic acid sodium salt). Guinea pigs were used to evaluate the effect of this agent on (1) acute airway obstruction produced by intravenous leukotriene B4, (2) pulmonary granulocyte infiltration and delayed onset airway obstruction resulting from a 4-h leukotriene B4 inhalation and (3) lung inflammation after aerosol challenge with the divalent cationic ionophore A23187 (6S-[6alpha(2S*,3S*),8beta(R*),9beta,11alpha]-5- (methylamino)-2-[[3,9,11-trimethyl-8-[1-methyl-2-oxo-2-(1H-pyrrol-2-yl)e thyl]-1,7-dioxaspiro[5.5]undec-2-yl]methyl]-4-benzoxazole carboxylic acid). Airway obstruction was quantitated using pulmonary gas trapping measurements and lung inflammation was evaluated by bronchoalveolar lavage (BAL) and histology. LY293111 sodium produced a dose-related inhibition of acute leukotriene B4-induced airway obstruction when administered i.v. (ED50=14 microg/kg) or p.o. (ED50=0.4 mg/kg). In contrast, LY293111 sodium did not inhibit the pulmonary gas trapping caused by aerosols of histamine, leukotriene D4, or the thromboxane mimetic U46619 (15 [(S)-hydroxy11a,9a-(epoxymethano)prosta-5Z,13E-dienoic acid]). Oral LY293111 sodium inhibited leukotriene B4-induced bronchoalveolar lavage granulocyte infiltration and delayed onset airway obstruction at doses as low as 0.3 mg/kg. In A23187-challenged animals, pulmonary inflammation was markedly inhibited at 1 h, but not 2 h and 4 h post-exposure. We conclude that LY293 11 sodium is a selective leukotriene B4 receptor antagonist with potent pulmonary anti-inflammatory activity.

Phase I/II trial of recombinant methionyl human tumor necrosis factor binding protein PEGylated dimer in patients with active refractory rheumatoid arthritis

OBJECTIVE

To evaluate the safety, immunogenicity, pharmacokinetics, and efficacy of intravenous administration of tumor necrosis factor binding protein (TNFbp) dimer in patients with rheumatoid arthritis (RA).

METHODS

This phase I/II study was a multicenter, randomized, double blind, placebo controlled, ascending dose study evaluating TNFbp dimer administered by i.v. infusion. Thirty-three patients with RA divided into 3 cohorts received TNFbp dimer (30, 100, 300 microg/kg) or placebo during a 5 min infusion at baseline and at 3 and 6 weeks; patients were followed at routine intervals after each infusion through 77 days postinfusion. Pharmacokinetics were analyzed using a log-linear regimen and comparisons were made between half-life after first, 2nd, and 3rd doses. Plasma TNFbp dimer concentrations and serum antibody levels were used in the measurement of pharmacokinetics.

RESULTS

Administration of 30 microg/kg of TNFbp dimer was generally well tolerated; the maximum tolerated dose was 100 microg/kg. No serious adverse events were reported. A significant antibody response affected the half-life and clearance of TNFbp dimer at each dose group. Anti-TNFbp antibodies were noncytotoxic and nonagonistic. Clinical evaluations provided evidence of in vivo activity of TNFbp dimer in these patients.

CONCLUSION

TNFbp dimer administered to patients with long standing RA resulted in significant antibody production to the study drug. This effect reduced the half-life and clearance of the TNFbp. This TNFbp will not be a viable option for treating patients with RA secondary to immunogenicity.

Effects of PEGylated soluble tumor necrosis factor receptor type I (PEG sTNF-RI) alone and in combination with methotrexate in adjuvant arthritic rats

OBJECTIVE

To determine the potential combination benefit of treatment with PEG sTNF-RI and methotrexate in adjuvant arthritic rats.

METHODS

Lewis rats with adjuvant arthritis were treated by sc injections of either 3.0 or 0.3 mg/kg PEG sTNF-RI on days 9, 11, and 13 of adjuvant arthritis. The effects of PEG sTNF-RI treatment alone were compared to treatment with daily oral methotrexate (0.075, 0.06 or 0.045 mg/kg) or methotrexate in combination with PEG sTNF-RI. Efficacy was monitored by volume measurement of ankle joints, final paw weights and histologic evaluation with particular emphasis on bone lesions.

RESULTS

Treatment with 3.0 or 0.3 mg/kg PEG sTNF-RI alone resulted in 52% or 28% inhibition, respectively, of paw swelling as assessed by final paw weight. Treatment with methotrexate at either 0.075, 0.06, or 0.045 mg/kg gave 84%, 51% or 18% inhibition and combination treatment resulted in additive inhibitory effects. Histologic evaluation of ankle joints demonstrated 68% or 25% inhibition of bone resorption with PEG sTNF-RI alone at 3.0 or 0.3 mg/kg. Treatment with 0.075, 0.06 or 0.045 mg/kg methotrexate resulted in 98%, 76% or 40% inhibition of bone resorption. Additive benefit was best seen with the lower doses of methotrexate.

CONCLUSION

Combination therapy with PEG sTNF-RI and methotrexate results in additive benefit, with the final result being excellent inhibition of all arthritis parameters. Data from these studies supports the clinical investigation of the use of combination therapy of PEG sTNF-RI and methotrexate in rheumatoid arthritis patients.

Combination benefit of PEGylated soluble tumor necrosis factor receptor type I (PEG sTNF-RI) and dexamethasone or indomethacin in adjuvant arthritic rats

OBJECTIVE

To determine the potential combination benefit receptor of treatment with PEGylated soluble tumor necrosis factor type I (PEG sTNF-RI) and dexamethasone (dex) or indomethacin (indo) in adjuvant arthritic rats.

SUBJECTS

160 male Lewis Rats.

TREATMENT

PEG sTNF-RI, dex, indo.

METHODS

Rats with adjuvant arthritis were given daily oral dex (0.025 or 0.006 mg/kg) or indo (0.5 or 0.25 mg/kg) day 9-14, alone or in combination with PEG sTNF-RI (sc on days 9, 11, and 13 of arthritis). Efficacy was monitored by volume measurement of ankle joints, final paw weights and histologic evaluation with particular emphasis on bone lesions.

RESULTS

Treatment with 1 mg/kg PEG sTNF-RI alone resulted in 27% inhibition of final paw weights, dex alone (0.025 mg/kg) gave 25% inhibition and the combination resulted in 58% inhibition. Histologic evaluation of ankle joints demonstrated 48% inhibition of bone resorption with PEG sTNF-RI alone, 55% inhibition with dex alone and the combination treatment inhibited bone resorption by 100%. Inactive doses of PEG sTNF-RI (0.3 mg/kg) and dex (0.006 mg/kg) when combined resulted in 39% inhibition of paw swelling (AUC) and 39% inhibition of bone resorption. Combination treatment with indomethacin resulted in slight additive effects on inflammation parameters but no additive effects on bone resorption.

CONCLUSION

Combination therapy with PEG sTNF-RI and dexamethasone results in additive or synergistic effects depending on the dose. Combination therapy with indomethacin resulted in slight additive effects on paw swelling parameters, but no additive benefit on bone resorption. Data from these studies support the clinical investigation of the use of combination therapy of PEG sTNF-RI and dex or other corticosteroids in rheumatoid arthritis patients.

Regulatory decision strategy for entry of a novel biological therapeutic with a clinically unmonitorable toxicity into clinical trials: pre-IND meetings and a case example

The following material was derived from a synthesis of case histories taken from investigational new drug (IND) applications and drug sponsors' experiences, utilizing fictionalized data to avoid any resemblance to any proprietary information; any such resemblance is accidental. These examples are used as an instructional scenario to illustrate appropriate handling of a difficult toxicology issue. In this scenario, a drug caused a toxicity in animals that was detected only by histopathologic analysis; if it were to develop in patients, no conventional clinical methods could be identified to monitor for it. It is not unusual for a firm to cancel clinical development plans for a lead drug candidate that causes such a toxicity, especially if such a drug is intended for use as a chronic therapeutic in a population of patients with a chronic disease. This case synthesis was inspired by a Food and Drug Administration (FDA) agreement to allow such a product to proceed into clinical trials after substantive pre-IND discussions and agreement on well-considered toxicology program designs. The scientists most closely involved in the strategy development included the sponsor's toxicologist, veterinary toxicologic pathologist, and pharmacokineticist, as well as the FDA's reviewing pharmacologist. The basis of this decision was thorough toxicity characterization (1-month studies in 2 species); correlating toxicities with a particular cumulative area under the curve (AUC) in both species; identification of the most sensitive species (the species that showed the lower AUC correlating with toxicity); allometric assessment of clearance of the drug in 3 nonhuman species; construction of a model of human kinetics (based on extrapolation from animal kinetics); and finally, estimation of clinical safety factors (ratios of the human estimated cumulative AUC at the proposed clinical doses, over the animal cumulative AUC that correlated with the no adverse effect levels). Industry and FDA scientists negotiated a joint assessment of risk and benefit in patients, resulting in the FDA permitting such a compound to enter into clinical trials for a serious autoimmune disease. Such constructive, early communication starts with the pre-IND meeting, and the conduct and planning for this meeting can be very important in establishing smooth scientific and regulatory groundwork for the future of a drug under IND investigation.

Different roles of tumour necrosis factor alpha and interleukin 1 in murine streptococcal cell wall arthritis

In this study two different aspects of tumour necrosis factor alpha (TNF-alpha) and interleukin 1 (IL-1) in locally induced murine streptococcal cell wall arthritis (SCW) were investigated. First, the kinetics and interdependence of TNF-alpha and IL-1 release; and second; their involvement in inflammation and cartilage destruction. Kinetic studies showed that the TNF-alpha peak level preceded the IL-1 peak level. However, in vivo neutralization of TNF-alpha did not result in decreased IL-1 bioactivity or immunoreactivity, suggesting that there is no dominant TNF-alpha-dependent IL-1 release in this model. Inflammation was studied by measuring knee joint swelling and inflammatory cell influx. Impact on cartilage was studied by measuring chondrocyte proteoglycan synthesis and cartilage proteoglycan depletion. The role of TNF-alpha in these phenomena was investigated using anti-TNF-alpha antibodies and tumour necrosis factor binding protein (TNFbp). Similarly, the role of IL-1 was studied using anti-IL-1 antibodies or IL-1 receptor antagonist (IL-1Ra). Anti-TNF-alpha treatment significantly reduced joint swelling, whereas this effect was not found by using anti-IL-1 or IL-1Ra. In contrast, neutralization of IL-1, but not TNF-alpha, resulted in a significant decrease of chondrocyte proteoglycan synthesis inhibition. Moreover, histology revealed that anti-IL-1 treatment reduced cartilage proteoglycan depletion and inflammatory cell influx. Combined anti-TNF-alpha/anti-IL-1 treatment significantly suppressed both inflammation and cartilage damage. However, the impact on these separate parameters did not exceed the effects of either anti-TNF-alpha or anti-TNF-1. It can be concluded that both TNF-alpha and IL-1 exert specific activities in SCW arthritis. The involvement of TNF-alpha in this model is limited to joint swelling, whereas IL-1 plays a dominant role in cartilage destruction and inflammatory cell influx.

Prevention of murine collagen-induced arthritis in the knee and ipsilateral paw by local expression of human interleukin-1 receptor antagonist protein in the knee

OBJECTIVE

To determine the efficacy of local human interleukin-1 receptor antagonist (HuIL-1Ra) gene therapy in murine collagen-induced arthritis (CIA).

METHODS

DBA/1 mice were immunized against bovine type II collagen. Before the onset of arthritis, NIH/3T3 fibroblasts transfected with pMFG-IRAP were transplanted into the knee cavity. Normal NIH/3T3 cells served as controls. Paws were evaluated macroscopically for redness, swelling, and deformities during the course of arthritis. Swelling of the knee joints was measured by external gamma counting of 99mtechnetium accumulation in the joint. Paws and knee joints were dissected and processed for histologic studies to evaluate inflammation and cartilage destruction.

RESULTS

The NIH/3T3 fibroblasts survived in the joint cavity of DBA mice for at least 7 days. The transduced cells expressed immunoreactive and bioactive HuIL-1Ra in the knee joint, and produced sufficient amounts to block the effect of 1 ng of recombinant murine IL-1alpha on chondrocyte proteoglycan synthesis. The onset of CIA was almost completely prevented in knee joints containing HuIL-1Ra-producing cells, whereas joints containing normal cells showed severe inflammation and destruction of cartilage. Moreover, onset of CIA in the draining joints (ipsilateral paws) of the HuIL-1Ra gene-bearing knees was also prevented.

CONCLUSION

Local production of HuIL-1Ra in the knee was able to ameliorate the effects of IL-1 on cartilage and could prevent the onset of CIA not only in that knee, but also in the "draining" paw. This indicates the feasibility of gene transfer as a therapeutic approach to modulating arthritis.

Aerosolized LTB4 produces delayed onset increases in pulmonary gas trapping

Airway obstruction, as measured by increases in postmortem pulmonary gas trapping, and lung inflammatory changes were examined in guinea pigs exposed for up to 4 h to aerosols of leukotriene B4 (LTB4) or its non-chemotactic isomer, 6-trans-12-epi-LTB4. Airway obstruction and cytological responses in isomer-exposed animals were similar to those of unexposed control animals. LTB4-exposed animals had minimal inflammatory changes at 0.5 h but became dyspneic by 2 h and had increased airway obstruction, bronchoalveolar lavage neutrophils and eosinophils, and pulmonary tissue granulocyte scores. The LTB4-induced effects at 4 h were similar to those 2 h, except for further increase in BAL neutrophils and eosinophils. LTB4-induced airway obstructive and inflammatory changes were prevented by pretreatment with the LTB4 receptor antagonist SC-41930, but were unaffected by indomethacin. Thus, prolonged LTB4 inhalation can produce delayed onset airway obstruction that is stereospecific, cyclooxygenase-independent, and temporally associated with the influx of granulocytes into lung airways.

Hyperoxia increases airway cell S-phase traversal in immature rats in vivo

Exposure of 21-day-old Sprague-Dawley rats to hyperoxia (> 95% O2 for 8 days) causes thickening of the airway epithelial and smooth muscle layers. To test the hypothesis that hyperoxic exposure increases airway layer DNA synthesis, we labeled the nuclei of cells undergoing S-phase by administering the thymidine analog bromodeoxyuridine (BrdU). BrdU was administered on days 3 and 4, 5 and 6, or 7 and 8 of air or O2 exposure, and the lungs were harvested immediately thereafter. Histologic sections were stained with an avidin-biotin-immunoperoxidase stain that revealed BrdU incorporation into nuclei, and a hematoxylin counterstain. After 4 days of air or O2 exposure, there was no difference in BrdU fractional labeling between control and hyperoxic animals. Thereafter, fractional BrdU labeling of the small airway (circumference < 1,000 microns) epithelium and smooth muscle layer was significantly increased in O2-exposed animals (P < 0.01, unpaired t test). The fractional labeling of larger, central airway smooth muscle layer cells was also increased after 8 days of O2 exposure (P < 0.01). In another cohort of O2-exposed animals, measurements of airway layer dimensions demonstrated increases in small airway epithelial and smooth muscle layer thickness that paralleled the time course seen for BrdU incorporation. We conclude that O2 exposure of immature rats increases airway epithelial and smooth muscle layer cellular DNA synthesis. These data suggest that hyperplasia of airway epithelial and smooth muscle layer cells may contribute to hyperoxia-induced airway remodeling.

Inhibition of IL-1 induced articular inflammation of rats by 4-aminothiazolidines, LY 221068 and LY 269415

LY 221068 and LY 269415 are representative compounds from a chemical series of 4-aminothiazolidines, with potent antioxidant properties in vitro. We have evaluated these two compounds in a rat model of articular inflammation caused by the administration of recombinant human IL-1 beta into the knee joints. IL-1 injection into the knee joints has been shown to cause a complex series of changes resulting in synovitis, mesenchymal proliferation, and subchondral bone and cartilage erosion. The inflammatory response of the knee joint was measured by determining the changes in the joint swelling and also by histological evaluation of the knee joints. Rats pretreated (p.o.) with 10-25 mg/kg of either of these compounds (4 h prior to IL-1 injection) displayed greatly reduced soft tissue swelling with an IC50 of 7.5 mg/kg. Evaluation of histological lesions revealed, however, that LY 269415 (IC50 of 10 mg/kg) was more potent than LY 221068 (IC50 of 25 mg/kg) in reducing the severity of histological changes. The results demonstrate that antioxidants of this chemical series either directly or indirectly display anti-inflammatory properties and could be beneficial as therapeutic agents in inflammatory arthritis.

Chronic toxicity, metabolism, and pharmacokinetics of the 5-HT3 receptor antagonist zatosetron (LY277359) in Fischer 344 rats

Studies were done to characterize the chronic toxicity, metabolism, and pharmacokinetics of a 5-HT3 receptor antagonist in Fischer 344 rats. Animal were given daily gavage doses of 10, 30, or 90 (females only were increased from 90 to 120 mg/kg for months 7-12) mg/kg of zatosetron for 1 year. Treatment-related histologic changes occurred primarily in the liver and kidney of rats given 30 or 90/120 mg/kg and consisted of hepatocellular fatty change (males only), hepatic granuloma formation, and histiocytosis (females only), and renal pigment deposition (both sexes), lesions not previously described in animals treated with 5-HT3 receptor antagonists. Decreased erythrocyte parameters, increased total leukocyte, lymphocyte, and neutrophil counts, and increased serum alkaline phosphatase, gamma glutamyltransferase, alanine transaminase, and liver weights in females were most likely related to the chronic inflammatory process in the liver. Increased alanine transaminase and transiently increased alkaline phosphatase with increased liver weights in males were likely related to the hepatocellular fatty change. Increased renal tubular epithelial pigment deposition (lipofuscin and hemosiderin) was observed in males and females in the high-dose group and in females in the middle-dose group. Both had increased kidney weights and increased serum inorganic phosphorus. Females in the high-dose group had increased urine volume, decreased pH, and increased total excretion of sodium, potassium, chloride, and creatinine. These changes may have been a reflection of tubular dysfunction associated with excessive pigment deposition. No toxicologically significant effects occurred in rats treated with 10 mg/kg/day for 1 year. Plasma concentrations of zatosetron and its 3-hydroxy metabolite increased with increasing dose and duration of dosing in both males and females during the first 6 months of dosing. Subsequent values measured at 12 months showed no substantive increases except in males given the highest dose. At comparable doses, consistent sex differences (F > M) in mean 1-hr plasma content of parent compound were evident across dose and time. Zatosetron-induced hepato- and nephrotoxicity seems to be peculiar to the rat and is observed only at very high doses relative to the proposed human clinical dose.

Effect of dexamethasone on A23187-induced airway responses in the guinea pig

We examined the effect of dexamethasone on A23187-induced bronchospasm, pulmonary inflammation and airway responses to substance P. Guinea pigs, dosed orally once a day for 4 days with dexamethasone (3.0, 10.0 or 30.0 mg/kg) or saline, were exposed to an aerosol of A23187 for 12 min or until labored breathing began. Postmortem pulmonary gas trapping was used as an indicator of in vivo airway obstruction and changes in bronchial responses. Dexamethasone did not alter airway obstruction or inflammation 1 h after A23187 exposure. However, dexamethasone reduced the enhanced airway responses to substance P and bronchiolar/peribronchiolar inflammation 24 h post-A23187. It is possible that glucocorticosteroid suppression of A23187-induced pulmonary inflammation was important in reducing the increased airway responses to substance P.

Effect of weight manipulation on bone loss due to ovariectomy and the protective effects of estrogen in the rat

While characterizing the effects of estrogen on an ovariectomized (OVX) rat model of bone loss, we examined several weight-matching regimens [e.g., ad libitum (feed bins continually full), weight matched (rate of weight gain for OVX and Sham-OVX groups was equalized), and weight restricted (weight gain rates for all groups were equalized to that of estrogen-treated OVX rats)] for possible effects. Bone loss following ovariectomy is primarily the result of an increase in bone resorption and is extremely sensitive to the effects of estrogens. Thus, in all of our analyses, treatment with 17 beta-estradiol served as a positive control for the prevention of bone loss. Each weight-matching study had three groups: control (Sham-OVX), OVX, and OVX + 17 beta-estradiol (0.1 mg/kg/day), and lasted for either 2, 4, or 6 weeks. Throughout the study, each Sprague Dawley rat was weighed every other day, and following sacrifice, a femur was removed for bone mineral density (BMD) analysis at the distal metaphysis by single photon absorptiometry. Following 2 weeks of dietary modifications, no significant differences were detected in BMD among the ad lib or weight matched groups. However, an estradiol-preventable reduction in BMD in restricted OVX rats was detected at 2 weeks postovariectomy. Additionally, OVX rats in all three dietary regimens displayed an estrogen-preventable reduction in proximal femur BMD at 4 and 6 weeks postovariectomy. These results indicate that a 4-week rat ovariectomized model of bone loss, under conditions of ad libitum feeding, shows great potential for pharmacologic manipulation.

Sulfuric acid induces airway hyperresponsiveness to substance P in the guinea pig

We investigated whether sulfuric acid inhalation would cause hyperresponsiveness to substance P. Guinea pigs became dyspneic during a 1 h sulfuric acid exposure, but recovered by 24 h when they were challenged with substance P or histamine aerosols. Eight minutes after the start of challenge, animals were killed and excised lung gas volumes measured. Sulfuric acid slightly increased histamine responsiveness compared to controls. However, sulfuric acid caused a much more pronounced leftward shift in the dose response to substance P. Coadministration of the neutral endopeptidase (NEP) inhibitor, thiorphan, did not reduce sulfuric acid-related hyperresponsiveness to substance P. By 72 h, sensitization to substance P was absent. Histological evaluation of sulfuric acid-treated lungs revealed mild alveolitis at 24 h, but not at 72 h. We conclude that sulfuric acid produces a marked sensitization to substance P. Inactivation of NEP does not appear to account for this effect.

Inhaled A23187 produces a preferential sensitization to substance P

We examined the effect of A23187-induced lung injury on airway responses to a variety of bronchoconstrictive aerosols in conscious guinea pigs. Guinea pigs were exposed to aerosolized A23187 or vehicle for 12 min or until labored breathing began. Animals were allowed to recover for 24 h, and then they were challenged with inhaled histamine, leukotriene D4 (LTD4), platelet-activating factor (PAF), or substance P. Eight minutes after start of the bronchoprovocative aerosol, the guinea pigs were killed and excised lung gas volume (ELGV) measurements were used as an index of in vivo airway obstruction. No differences in ELGV dose-response curves to LTD4 were seen in A23187- and vehicle-exposed animals. A23187 exposure produced small increases in both histamine and PAF sensitivity. However, A23187 caused a much more pronounced leftward shift in the dose-response to substance P. Coadministration of the neutral endopeptidase inhibitor, thiorphan, did not reduce the A23187-related airway responses to substance P. Histologic evaluation of A23187-treated lungs revealed peribronchiolar inflammation, bronchiolar epithelial injury, and mild alveolitis. We conclude that A23187 treatment produces differential airway responses to bronchoactive agents, with a preferential sensitization to substance P.

Hepatocellular proliferation in ibuprofen-treated mice

Female B6C3F1 mice were treated with ibuprofen for 2 wk or 90 days to monitor effects on hepatocellular proliferation during acute and subchronic exposure. Proliferation was assessed by bromodeoxyuridine labeling. Mice treated with 100, 200, or 400 mg/kg ibuprofen for 2 wk had significantly increased liver weights. A dose-related increase in the number of labeled hepatocytes per 1,000 hepatocytes suggested that the weight increases were in part a result of hepatocellular proliferation. Hepatocellular hypertrophy also contributed to the increased liver size as indicated by decreases in the number of hepatocytes per high power field. Ultrastructural evaluation indicated that hepatocyte peroxisome size increased significantly in treated mice. Mice treated with 100 or 200 mg/kg ibuprofen for 90 days and given bromodeoxyuridine during the last 2 wk of ibuprofen exposure had statistically significant increases in relative liver weights. However, the number of labeled hepatocytes per 1,000 hepatocytes was not increased, and there was no evidence of hepatocellular hypertrophy. Mice given 200 mg/kg ibuprofen for 90 days had significantly decreased serum triglycerides. These findings indicate that ibuprofen treatment of mice results in hepatomegaly characterized by hepatocellular hypertrophy and hyperplasia. Peroxisomal changes may be contributory to the pathogenesis of this lesion.

Pharmacological and histological examinations of regional differences of guinea-pig lung: a role of pleural surface smooth muscle in lung strip contraction

1. Parenchymal lung strip preparations have been widely used as an in vitro model of peripheral airway smooth muscle. The present study examined functional responses of 4 consecutive guinea-pig lung parenchymal strips isolated from the central region (segment 1) to the distal edge (segment 4) of the lower lung lobe. The middle two segments were designated as segments 2 and 3. 2. Lung segments 1 and 4 exhibited significantly greater contraction than the other 2 segments to KCl when responses were expressed as mg force per mg tissue weight. Contractile responses to bronchospastic agents including histamine, carbachol, endothelin-1, leukotrienes (LT) B4 and D4, and the thromboxane A2-mimetic U46619 demonstrated no significant difference in EC50 values among the 4 lung segments. 3. Contractile responses of segments 1 and 4 to antigen-challenge (ovalbumin), ionophore A23187 and substance P were significantly greater than the other 2 segments with respect to either sensitivity or maximum responsiveness. 4. U46619-induced contractions of the 4 lung segments were relaxed in similar manner by papaverine and theophylline up to 100%, salbutamol up to 80%, and sodium nitroprusside by only 20%. In contrast, sodium nitroprusside markedly reversed U46619-induced contraction of pulmonary arterial rings and bronchial rings. 5. Histological studies identified 2-4 layers of smooth muscle cells underlying the lung pleural surface. Mast cells were prominent in this area. Moreover, morphometric studies showed that segment 4 possessed the least amount of smooth muscle structures from bronchial/bronchiolar wall and vasculatures as compared to the other 3 segments, and a significant difference in this respect was evident between segment 1 and segment 4.6. Since lung segments 1 and 4 are covered with larger surface area of lung pleura, the present results suggest that the significantly greater intrinsic contractile responses of segments 1 and 4 are associated with the presence of increased lung pleural surface possibly together with more mast cells. Thus, a primary contribution to the net contraction of the lung parenchymal strips may be smooth muscle from the lung pleura, alveolar ducts and interstitial contractile cells rather than from bronchi/bronchioles and microvasculatures.

Correlation of anti-inflammatory activity with peak tissue rather than peak plasma levels of BF389

BF389 (Biofor 389) is a potent anti-inflammatory agent in various animal models including adjuvant and type II collagen arthritis in rats. In vitro assays indicate that this compound is a mixed inhibitor of arachidonic acid metabolism. The compound was evaluated for effects on the acute inflammatory response in the carrageenan paw edema assay in rats using a standard protocol in which the animals were given single or multiple (daily for 5 days) p.o. doses of the compound. Carrageenan was injected into the footpad of each animal 1 hr after dosing and volumes of both hind paws were determined 3 hr later. Basal serum prostaglandin (PG) E2 levels and PGE2 levels in arachidonate-stimulated blood from these same animals also were measured. No anti-inflammatory activity was observed in BF389-treated rats despite the occurrence of profound suppression of basal and stimulated PGE2 production. Animals treated with conventional nonsteroidal anti-inflammatory drugs in this assay had both suppressed PGE2 production and significant anti-inflammatory activity. In another study, groups of rats were given p.o. doses of 1, 10, 100 or 250 mg/kg of BF389 for 5 days in order to determine peak concentrations, T1/2s and total areas under the plasma (tissue) drug concentration curves in plasma and paws. Peak plasma concentrations occurred 2 to 4 hr postdosing and the half-life was 8 to 15 hr over the 1- to 250-mg/kg/day dose range. Peak paw concentrations occurred 6 to 12 hr postdosing and the levels were 9- to 14-fold greater in the paw than in the plasma.(ABSTRACT TRUNCATED AT 250 WORDS)