Regulation of human normal and osteoarthritic chondrocyte interleukin-1 receptor by antirheumatic drugs

Inhibition of protein kinase CK2 facilitates cellular senescence by inhibiting the expression of HO-1 in articular chondrocytes

Protein kinase casein kinase 2 (CK2) is important in the regulation of cell proliferation and death, even under pathological conditions. Previously, we reported that CK2 regulates the expression of heme oxygenase‑1 (HO‑1) in stress‑induced chondrocytes. In the present study, it was shown that CK2 is involved in the dedifferentiation and cellular senescence of chondrocytes. Treatment of primary articular chondrocytes with CK2 inhibitors, 4,5,6,7‑terabromo‑2‑azabenzimidazole (TBB) or 5,6‑dichlorobenzimidazole 1‑β‑D‑ribofuranoside (DRB), induced an increase in senescence‑associated β‑galactosidase (SA‑β‑gal) staining. In addition, TBB reduced the expression of type II collagen and stimulated the accumulation of β‑catenin, phenotypic markers of chondrocyte differentiation and dedifferentiation, respectively. It was also observed that the abrogation of CK2 activity by CK2 small interfering RNA induced phenotypes of chondrocyte senescence. The association between HO‑1 and cellular senescence was also examined in CK2 inhibitor‑treated chondrocytes. Pretreatment with 3‑morpholinosydnonimine hydrochloride, an inducer of the HO‑1 expression, or overexpression of the HO‑1 gene significantly delayed chondrocyte senescence. These results show that CK2 is associated with chondrocyte differentiation and cellular senescence and that this is due to regulation of the expression of HO‑1. Furthermore, the findings suggest that CK2 is crucial as an anti‑aging factor during chondrocyte senescence.

[Muscle, tendon and joint injections : What is the evidence?]

Injections at tendon insertions, in muscles and in joints are an important instrument in the conservative treatment of musculoskeletal diseases, for acute injuries as well as for chronic degenerative diseases. Local anesthetic agents and glucocorticoids are well-established medications; however, severe side effects, such as chondrolysis have sometimes been reported, particularly for local anesthetic agents. In addition platelet rich plasma (PRP) and hyaluronic acid are also widely used; however, the clinical effectiveness has not always been proven. This article gives an overview on the most commonly used medications for injections and the mechanisms of action. The indications for treatment and the evidence for the clinical adminstration of muscle, tendon and joint injections are described based on the currently available literature.

Induction of heme oxygenase‑1 expression protects articular chondrocytes against cilostazol‑induced cellular senescence

Chondrocyte senescence is associated with the aging and degeneration of cartilage, and eventually leads to joint destruction. The aim of this study was to elucidate the mechanisms responsible for the cytoprotective effects of heme oxygenase‑1 (HO‑1) on chondrocytes in cartilage. Chondrocyte senescence was induced using cilostazol and measured using a specific senescence‑associated β‑galactosidase (SA‑β‑gal) staining assay. Cilostazol altered the expression of type Ⅱ collagen and β‑catenin, which are phenotypic markers of the differentiation and dedifferentiation of chondrocytes. Cilostazol also significantly induced HO‑1 expression, and the induction of HO‑1 expression was affected by a significant increase in reactive oxygen species (ROS) production caused by cilostazol treatment. Of note, pre‑treatment with 3‑morpholinosydnonimine hydrochloride (SIN‑1), an inducer of HO‑1 expression, markedly attenuated cilostazol‑induced chondrocyte senescence, and thus, we examined whether HO‑1 directly modulates chondrocyte senescence induced by cilostazol. The upregulation of HO‑1 was found to suppress cilostazol‑induced cellular senescence. In addition, the inhibition of HO‑1 activity with the iron chelator, desferrioxamine (DFO), or HO‑1 siRNA increased cilostazol‑induced chondrocyte senescence. Based on these results, it can be concluded that HO‑1 is associated with the suppression of chondrocyte senescence, and that the enforced overexpression of HO‑1 protects chondrocytes against stress‑induced senescence.

Gait and behavior in an IL1β-mediated model of rat knee arthritis and effects of an IL1 antagonist

Interleukin-1 beta (IL1β) is a proinflammatory cytokine that mediates arthritic pathologies. Our objectives were to evaluate pain and limb dysfunction resulting from IL1β over-expression in the rat knee and to investigate the ability of local IL1 receptor antagonist (IL1Ra) delivery to reverse-associated pathology. IL1β over-expression was induced in the right knees of 30 Wistar rats via intra-articular injection of rat fibroblasts retrovirally infected with human IL1β cDNA. A subset of animals received a 30 µl intra-articular injection of saline or human IL1Ra on day 1 after cell delivery (0.65 µg/µl hIL1Ra, n = 7 per group). Joint swelling, gait, and sensitivity were investigated over 1 week. On day 8, animals were sacrificed and joints were collected for histological evaluation. Joint inflammation and elevated levels of endogenous IL1β were observed in knees receiving IL1β-infected fibroblasts. Asymmetric gaits favoring the affected limb and heightened mechanical sensitivity (allodynia) reflected a unilateral pathology. Histopathology revealed cartilage loss on the femoral groove and condyle of affected joints. Intra-articular IL1Ra injection failed to restore gait and sensitivity to preoperative levels and did not reduce cartilage degeneration observed in histopathology. Joint swelling and degeneration subsequent to IL1β over-expression is associated limb hypersensitivity and gait compensation. Intra-articular IL1Ra delivery did not result in marked improvement for this model; this may be driven by rapid clearance of administered IL1Ra from the joint space. These results motivate work to further investigate the behavioral consequences of monoarticular arthritis and sustained release drug delivery strategies for the joint space.

Clinical benefits of intra-articular anakinra for arthrofibrosis

Postoperative inflammation and stiffness, as well as the struggle to achieve full range of motion (ROM), following knee surgery is a significant clinical challenge. Interleukin-1 is a crucial mediator of the inflammatory response and development of pathological conditions leading to chronic inflammation. We hypothesized that intra-articular injection of intra-articular anakinra, an IL-1 antagonist, would result in sustained improvements of chronic refractory arthrofibrosis and limited arthrofibrosis of the knee joint. We retrospectively reviewed 8 patients who underwent injection of intra-articular anakinra, 200 mg. Four patients (3 women, 1 man) had intra-articular anakinra for treatment of chronic refractory arthrofibrosis, and 4 patients (4 women) had intra-articular anakinra for limited arthrofibrosis. All 4 of the refractory arthrofibrosis patients had failed conservative treatment with intensive physical therapy, corticosteroid injections, and anti-inflammatory medication. Three of the 4 patients had failed a prior manipulation under anesthesia with lysis of adhesions. All 4 reported improvement in ROM (10°-45°) and swelling, with 75% reporting improvement in pain. Seventy-five percent of these patients returned to prior activity level. All 4 of the limited arthrofibrosis also failed similar attempts at conservative treatment, and 2 of the 4 had failed a prior manipulation under anesthesia with lysis of adhesions. After intra-articular anakinra, all 4 reported improvement in ROM (20°-45°) and swelling, with 80% reporting improvement in pain. Seventy-five percent of these patients were able to return to prior activity level. We found intra-articular anakinra to be effective in this small cohort of patients with refractory arthrofibrosis and limited arthrofibrosis.

Acute phase response in patients undergoing lumbar spinal surgery: modulation by perioperative treatment with naproxen and famotidine

In orthopaedic surgery, perioperative administration of non-steroidal anti-inflammatory drugs has been shown to reduce postoperative pain and analgesic consumption. In addition, preoperative administration of ibuprofen has proved to reduce interleukin-6 (IL-6) release, while that of ranitidine reduced postoperative IL-6-induced C-reactive protein synthesis in patients undergoing abdominal surgery. However, it has not been established whether the preoperative administration of both types of drugs may reduced the postoperative inflammatory reaction after instrumented spinal surgery. Accordingly, our objective was to investigate the effects of preoperative treatment with naproxen plus famotidine on the postoperative systemic inflammatory reaction in patients undergoing instrumented lumbar spinal surgery. Forty consecutive patients scheduled for elective instrumented spinal fusion were alternately assigned to receive either naproxen (500 mg/day, p.o.) plus famotidine (40 mg/day, p.o.) for 7 days before operation, or no adjuvant treatment. Haematological parameters, acute phase proteins, complement fractions, immunoglobulins and cytokines were determined 7 days and immediately before surgery, and on days 0, 1, 2 and 7 after surgery. Haematological parameters, clinical data, duration of surgery, blood loss, perioperative blood transfusion and postoperative complications were similar in the two groups, although pretreated patients showed lower increases in body temperature and required less analgesic medication. Compared with preoperative levels, IL-6 levels were significantly increased postoperatively in all patients with no differences between groups. C-reactive protein, alpha(1)-acid-glycoprotein and haptoglobin levels were also significantly increased postoperatively in all patients; however, they were significantly lower in pretreated patients. In conclusion, perioperative treatment with naproxen plus famotidine was well tolerated and reduced the acute phase response after instrumented spinal surgery. However, further research is needed to determine the best dose and timing of preoperative treatment administration, and to correlate these changes with long-term clinical results.

An in vitro screening assay for inhibitors of proinflammatory mediators in herbal extracts using human synoviocyte cultures

Tumor necrosis factor-alpha (TNF-alpha), cyclooxygenase (COX)-2, and prostaglandin (PG)E-2 play a critical role in the pathophysiology of arthritis. Tumor necrosis factor-alpha mediates induction of other cytokines, COX-2, PGs, and metalloproteinases, which leads to cartilage degradation. We developed an in vitro human synoviocyte assay system for screening inhibitors of proinflammatory mediators in herbal extracts. Synoviocytes (5 x 10(5) cells/well) obtained during primary knee replacement from osteoarthritic patients were incubated with: control media alone or ginger extract (hydroxy-methoxy-phenyl compounds [HAPC]: EV.EXT 77), 1 h before activation with 1 ng/ml TNF-alpha, 10 ng/ml interleukin-1beta, or control media alone at 5% carbon dioxide, 37 degrees C. Cell viability, TNF-alpha, COX-2, PGE-2, nuclear factor kappaB (NF-kappaB), and inhibitory subunit I kappa B-alpha (IkappaB-alpha) expression were analyzed by reverse transcriptase-polymerase chain reaction, enzyme-linked immunosorbent assay, electrophoretic mobility shift assay, and Western blots. Ginger extract-HAPC (100 microg/ml) significantly inhibited the activation of TNF-alpha and COX-2 expression in human synoviocytes as well as suppressed production of TNF-alpha and PGE-2. Inhibition of TNF-alpha and COX-2 activation was accompanied by suppression of NF-kappaB and IkappaB-alpha induction. Using our in vitro assay, we discovered that the ginger extract blocks activation of proinflammatory mediators and its transcriptional regulator suggesting its mode of action. These observations indicate that ginger extract-HAPC offers a complementary and alternative approach to modulate the inflammatory process involved in arthritis.

Arthroscopic evaluation of potential structure-modifying drug in osteoarthritis of the knee. A multicenter, randomized, double-blind comparison of tenidap sodium vs piroxicam

OBJECTIVE

To test the hypothesis that tenidap has a structure-modifying effect in human knee osteoarthritis.

DESIGN

STUDY

multicenter, prospective, randomized, double blind, 1 year duration.

PATIENTS

primary painful knee osteoarthritis (ACR criteria) of the medial tibiofemoral compartment, medial joint space width > or =2mm, at least 10% of one cartilage surface of the medial compartment affected by superficial fibrillation or worse at baseline arthroscopy. STUDY MEDICATION: once daily dosage of either tenidap 40 mg, tenidap 120 mg or piroxicam 20mg. STUDY ENDPOINTS: bilateral extended weight-bearing X-rays and knee arthroscopy under local anaesthesia were done at entry and after 1 year. Joint space width was measured in millimeters at the narrowest point of the medial compartment. Chondropathy was scored by using reader's overall assessment (VAS score, 100mm) and Société Française d'Arthroscopie (SFA) score (0-100).

RESULTS

Patients (665) were randomized and 494 completed the study. After 1 year, intra-group radiological changes and radiological difference between both tenidap groups and the piroxicam group did not reach statistical significance. The intra-group arthroscopic deterioration of chondropathy was low, but statistically significant in the three study groups. However, there was no statistically significant difference between both tenidap groups and the piroxicam group.

CONCLUSIONS

This study failed to demonstrate any difference between the treatment arms with regard to the structural progression of medial knee osteoarthritis as measured by radiography and arthroscopy. Arthroscopy did, however, appears to be more sensitive in detecting disease progression than the weight-bearing radiographs with fully extended knees. This study shows that it is possible to complete a large international trial using arthroscopy as an outcome measure of articular cartilage.

Effects of carprofen and dexamethasone on canine chondrocytes in a three-dimensional culture model of osteoarthritis

OBJECTIVE

To determine effects of carprofen and dexamethasone on chondrocytes in a culture model of osteoarthritis (OA).

SAMPLE POPULATION

Chondrocytes isolated from articular cartilage of the humeral head of 5 adult dogs.

PROCEDURE

Chondrocytes were harvested, cultured and subcultured in monolayer, and then cultured in a 3-dimensional (3-D) medium. Cells from each dog were distributed into 6 groups with differing content of liquid medium for each 3-D construct (agarose [AG], AG plus interleukin [IL]-1beta, AG plus carprofen [4 microg/mL], AG plus dexamethasone [1 mg/mL], AG plus IL-1beta [20 ng/mL] plus carprofen [4 microg/mL], and AG plus IL-1beta (20 ng/mL) plus dexamethasone (1 mg/mL). On days 3, 6, 12, and 20 of culture, samples from all groups were collected. Liquid media were assayed for glycosaminoglycan, prostaglandin (PG)E2, matrix metalloprotease (MMP)-3, and MMP-13 concentrations. All 3-D constructs were evaluated for viability, cell morphology, proteoglycan staining, and collagen type-II concentration. Total glycosaminoglycan content in each 3-D construct was quantitated by spectrophotometric assay.

RESULTS

Addition of IL-1beta caused a significant loss of cell viability and matrix production. Addition of carprofen or dexamethasone caused significant decreases in PGE2 in the liquid media, and each was minimally effective in protecting chondrocytes against negative effects of IL-1beta.

CONCLUSIONS AND CLINICAL RELEVANCE

Human recombinant IL-1beta resulted in loss of cell viability, alterations in extracellular matrix components, and production of PG and MMP Carprofen and dexamethasone had little effect on cell and matrix variables but did decrease PGE2 concentrations and primarily affected the inflammatory pathway of osteoarthritis.

Effects of chondroitin sulfate and interleukin-1beta on human chondrocyte cultures exposed to pressurization: a biochemical and morphological study

Objective This study investigated the in vitro effects of chondroitin sulfate (CS) on human articular chondrocytes cultivated in the presence or in the absence of interleukin-1beta (IL-1beta) during 10 days of culture with and without pressurization cycles. Design The effects of CS (10 and 100 microg/ml) with and without IL-1beta were assessed in the culture medium of cells exposed to pressurization cycles in the form of synusoidal waves (minimum pressure 1 Mpa, maximum pressure 5 Mpa) and a frequency of 0.25 Hz for 3 h by immunoenzymatic method on microplates for the quantitative measurement of human proteoglycans (PG). On the 4th and 10th day of culture the cells were used for morphological analysis by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Results The presence of IL-1beta determines a significant decrease in PG concentration measured in the culture medium. When the cells are cultured in the presence of IL-1beta and CS, a statistically significant restoration of PG levels is observed. Under pressurization conditions, we observed that PG concentration in the medium of cells presents a significant increase at baseline conditions, in the presence of IL-1beta+CS10 and IL-1beta+CS100, but not with IL-1beta alone. The results concerning metabolic evaluation are confirmed by the morphologic findings obtained by TEM and SEM. Conclusions These in vitro studies confirm the protective role of CS, which counteracts the IL-1beta induced effects and they confirm the importance of pressure on chondrocyte metabolism and morphology.

Tenidap enhances P2Z/P2X7 receptor signalling in macrophages

Tenidap is an anti-inflammatory drug whose mechanism of action is not fully understood. It has been shown to block plasma membrane anion transport and to decrease release of interleukin-1beta, probably via the inhibition of interleukin-1beta converting enzyme. In the present study we showed that: (a) tenidap increases the sensitivity of mouse macrophages to cytotoxic effects mediated by extracellular ATP; (b) tenidap increases lucifer yellow uptake through the macrophage ATP receptor; (c) pretreatment with oxidised ATP, a blocker of the P2Z/P2X7 receptor, inhibits cytotoxicity and lucifer yellow uptake due to the combined effects of ATP and tenidap; (d) macrophages lacking the P2Z/P2X7 receptor are resistant to the synergistic effect of tenidap and ATP. The results suggest that tenidap synergises with extracellular ATP for activation of the P2Z/P2X7 receptor.

Dedifferentiated chondrocytes cultured in alginate beads: restoration of the differentiated phenotype and of the metabolic responses to interleukin-1beta

Chondrocytes cultivated in monolayer rapidly divide and lose their morphological and biochemical characteristics, whereas they maintain their phenotype for long periods of time when they are cultivated in alginate beads. Because cartilage has a low cellularity and is difficult to obtain in large quantities, the number of available cells often becomes a limiting factor in studies of chondrocyte biology. Therefore, we explored the possibility of restoring the differentiated properties of chondrocytes by cultivating them in alginate beads after two multiplication passages in monolayer. This resulted in the reexpression of the two main markers of differentiated chondrocytes: Aggrecan and type II collagen gene expression was strongly reinduced from day 4 after alginate inclusion and paralleled protein expression. However, 2 weeks were necessary for total suppression of type I and III collagen synthesis, indicators of a modulated phenotype. Interleukin-1beta, a cytokine that is present in the synovial fluid of rheumatoid arthritis patients, induces many metabolic changes on the chondrocyte biology. Compared with cells in primary culture, the production of nitric oxide and 92-kDa gelatinase in response to interleukin-1beta was impaired in cells at passage 2 in monolayer but was fully recovered after their culture in alginate beads for 2 weeks. This suggests that the effects of interleukin-1beta on cartilage depend on the differentiation state of chondrocytes. This makes the culture in alginate beads a relevant model for the study of chondrocyte biology in the presence of interleukin-1beta and other mediators of cartilage destruction in rheumatoid arthritis and osteoarthrosis.

Isolated chondrons: a viable alternative for studies of chondrocyte metabolism in vitro

OBJECTIVE

To develop and test a simple enzymatic procedure for isolating chondrons, which consist of the chondrocytes and their surrounding pericellular microenvironment.

DESIGN

Chondrons were obtained by digesting adult human articular cartilage with a mixture of dispase and collagenase. Chondrons and chondrocytes were cultured in alginate beads, immunofluorescence labeled and examined by confocal microscopy.

RESULTS

Comparison of freshly isolated chondrons with cryostat sections of cartilage revealed that type VI collagen, type II collagen and aggrecan were retained, but fibronectin and a unique chondroitin sulfate epitope recognized by the antibody, 7D4, were lost. Comparison of enzymatic and mechanical homogenization methods revealed subtle changes in chondron morphology and retention of fibronectin in mechanically isolated chondrons. Average yield of enzyme-isolated chondrons was slightly lower than that of chondrocytes isolated by pronase and collagenase digestion, but was much greater than that reported for mechanically isolated chondrons. Enzyme-isolated chondron viability was greater than 80% 1 day after isolation, and continued to be above 80% through 7 weeks of alginate bead culture. Viability of isolated chondrocytes was initially greater than 80% but fell to 60-80% with time in culture. Chondrons and isolated chondrocytes had a similar division rate except osteoarthritic chondrons were significantly slower after 2 weeks in culture. Cell division was more rapid for nonosteoarthritic chondrons than for osteoarthritic ones.

CONCLUSIONS

Enzymatic isolation of chondrons is relatively simple, gives better yield and viability than mechanical isolation, but comparable yield and viability of traditional chondrocyte isolation. Enzymatic chondron isolation allows the effect of the in vivo-formed pericellular matrix on chondrocyte metabolism to be studied in vitro.

Effects of tenidap on the progression of osteoarthritic lesions in a canine experimental model. Suppression of metalloprotease and interleukin-1 activity

OBJECTIVE

To study, in vivo, the therapeutic effectiveness of tenidap, an antirheumatic drug, on the progression of lesions in an experimental osteoarthritis (OA) dog model. The action of tenidap on the activity and expression of metalloproteases in cartilage, as well as on the bioactivity of interleukin-1 (IL-1) in synovial fluid, was determined.

METHODS

The anterior cruciate ligament of the right stifle joint of 20 mongrel dogs was sectioned through a stab wound. Dogs were divided into 3 groups: group I (n = 7) received no treatment, group II (n = 6) was treated with oral omeprazole (20 mg/day), and group III (n = 7) received oral omeprazole (20 mg/day) and a therapeutic dosage of oral tenidap (3 mg/kg twice daily). Four weeks following surgery, the untreated dogs (group I) were killed, and drug treatments were begun for the other dogs (groups II and III). These dogs received medications for 8 weeks (weeks 4-12) and then were killed. Evaluations were made of the incidence and size of osteophytes as well as of the size and grade of cartilage erosions on both the condyles and plateaus. Histologic examination of the severity of the cartilage lesions and synovial inflammation was also performed. Activity levels of collagenase, stromelysin, and gelatinase as well as collagenase-1, collagenase-3, and stromelysin-1 messenger RNA were determined in the cartilage. The level of IL-1 activity in the synovial fluid was also measured.

RESULTS

Among the dogs with OA, lesions were more severe at 12 weeks than at 4 weeks. Group III (tenidap-treated) dogs had a slightly reduced incidence of osteophytes compared with the group II (12-week OA) dogs (71% versus 100%), and the size of the osteophytes was significantly diminished (mean +/- SEM 1.75 +/- 0.69 mm versus 4.38 +/- 0.64 mm). Macroscopically, tenidap decreased the size (condyles 6.00 +/- 2.18 mm2 versus 21.08 +/- 6.70 mm2, plateaus 15.50 +/- 4.77 mm2 versus 35.0 +/- 3.64 mm2) and the grade (condyles 0.57 +/- 0.20 versus 1.17 +/- 0.21, plateaus 1.07 +/- 0.22 versus 2.00 +/- 0.25) of the cartilage lesions compared with the 12-week OA dogs. At the histologic level, the severity of cartilage lesions was also decreased in the tenidap-treated dogs versus the 12-week OA dogs, both on the condyles (3.43 +/- 0.54 versus 5.55 +/- 0.38) and on the plateaus (3.39 +/- 0.35 versus 5.54 +/- 0.60). All 3 OA groups showed a significant and similar level of synovial inflammation. Tenidap markedly decreased collagenase, stromelysin, and gelatinase activity, as well as the level of expression of collagenase-3 in the cartilage. Interestingly, the activity level of IL-1 in synovial fluid was also significantly reduced in the tenidap-treated dogs.

CONCLUSION

Tenidap markedly reduced the severity of OA lesions, indicating the effect of this drug in decreasing the progression of disease. It appears that the drug acts by reducing the activity and/or expression of metalloproteases in cartilage, a process known to play a major role in the pathophysiology of OA lesions. This effect could be mediated by the suppressive effect of tenidap on IL-1 activity.

Action of anti-inflammatory drugs on interleukin-1 beta-mediated glucose uptake by synoviocytes

Synovial cell cultures prepared from samples taken from osteoarthritic and rheumatoid patients were treated with different anti-inflammatory agents (cortisol, indomethacin, ibuprofen and piroxicam) to determine their 'anti-interleukin-1 beta' action, using inhibition of interleukin-1 beta-mediated glucose uptake stimulation as a biological test. Confluent cells were treated for 24 h with different concentrations of these drugs (10(-5), 10(-6) and 10(-7) mol/l) to study their effect on the inflammation process. 6 h before glucose uptake studies, interleukin-1 beta (1 ng/ml) was added. Whereas non-steroid anti-inflammatory agents were inefficient, cortisol inhibited the action of interleukin-1 beta on glucose uptake. In osteoarthritic cells, cortisol, 10(-5) mol/l, reduced interleukin-1 beta-mediated glucose uptake by 27% after a 24-h incubation. In rheumatoid cells, stimulated 2-deoxy-D-glucose uptake was reduced by 40.6%. Results were similar when interleukin-1 beta and cortisol were added simultaneously, 6 h before glucose uptake was measured. This rapid effect of cortisol was protein synthesis-dependent (inhibited by cycloheximide). Cortisol decreased glucose uptake by synoviocytes by acting on basal and interleukin-1 beta-mediated glucose uptake. This effect was more pronounced in rheumatoid synovial cells. The inhibition of interleukin-1 beta-mediated glucose uptake could be proposed as a new model for studying the anti-interleukin-1 beta effects of anti-rheumatic drugs.

Inhibition of eicosanoid release from synovial organ culture by incubation with tepoxalin and its acid metabolite

The pharmacological profile of a novel dual inhibitor, tepoxalin and of its carboxylic acid metabolite on cyclooxygenase and lipoxygenase pathways was evaluated by in vitro incubation with synovial tissue. Tissue specimens obtained at surgery in rheumatoid arthritis (RA, n = 10) or osteoarthritis (OA, n = 11) patients were incubated. Tepoxalin (10(-7), 10(-6), 10(-5) M) decreased eicosanoid release calculated in % of tyrode control for OA: LTC4 to 71-33%, 6-keto-PGF1a to 37-20%, PGE2 to 29-6%. For RA: LTC4 to 56-22%, 6-keto-PGF1a to 43-22%, PGE2 to 57-32%. Similarly, its metabolite (10(-7), 10(-5)M) decreased release in OA: LTC4 to 99 and 60%, PGE2 to 42 and 20%, 6-keto-PGF1a to 54 and 25%. In RA:LTC4 to 81 and 45%, PGE2 to 61 and 30%, 6-keto-PGF1a to 46 and 18%. Significance (P < 0.05) was achieved for all but 1 group (LTC4 metabolite at 10(-7)M vs tyrode). In summary a marked and dose dependent decrease of LT and PG release was obtained when incubating the dual inhibitor tepoxalin and its active carboxylic acid metabolite with synovial tissue at doses expected to be reached in the joint during therapy.

Effects of tenidap on intracellular signal transduction and the induction of proinflammatory cytokines: a review

Tenidap is a novel, once-daily antirheumatic drug which has shown promising results against rheumatoid arthritis in extensive clinical trials. It combines NSAID-like cyclooxygenase inhibition with suppression of the acute phase response. In macrophages, tenidap inhibits the lipopolysaccharide-induced synthesis of interleukins-1 and -6, but it tends to potentiate the lipopolysaccharide-induced synthesis of tumor necrosis factor alpha, due to its cyclooxygenase inhibition. In macrophages, tenidap is a potent inhibitor of zymosan-induced responses, not only the induction of proinflammatory cytokines, but also arachidonate mobilization, protein phosphorylation, and inositol phosphate formation, possibly through interference with the receptor-mediated upregulation of phospholipase C. Tenidap also acts as an intracellular acidifier in many cell types, which may explain at least some of its other effects. Recent studies have indicated that, in addition to modulation of prostanoid and cytokine formation, tenidap has many other effects beneficial in rheumatic disease. It has been shown to inhibit bone resorption, neutrophil adhesion and degranulation, the interleukin-1-induced suppression of glycosaminoglycan synthesis, as well as the production of active metalloproteinases from chondrocytes.

Pharmacological and functional properties of voltage-independent Ca2+ channels

During the last few years, considerable progress has taken place in our knowledge of the molecular and functional properties of the various voltage-independent Ca2+ channels. In addition to the ionotropic receptor-channels (ROCs), that are not discussed in the present review, these channels include the SMOCs, activated via second messengers or other transducing processes directly triggered by receptor activation; and the SOCCs, activated as a consequence of depletion of the rapidly exchanging Ca2+ stores in the cytoplasm. In parallel, a pharmacological approach to the study of these channels has been developed, based primarily on heterogeneous drugs already known for different biological effects, and subsequently recognized as voltage-independent Ca(2+)-channel blockers. From the systematic analysis of the effects of these drugs new information has emerged about SMOCs and SOCCs function. In addition, pharmacological blockade of these channels appears to have beneficial therapeutic effects in pathological conditions such as tumoral cell growth, inflammation and immunity. At the moment the field is rapidly evolving, with major developments expected in the years ahead.

Tenidap, a structurally novel drug for the treatment of arthritis: antiinflammatory and analgesic properties

Tenidap is a new anti-rheumatic agent which has clinical properties characteristic of a disease modifying drug combined with acute antiinflammatory and analgesic activity. This paper details tenidap's cyclooxygenase (COX) inhibitory activity and the resulting pharmacological properties in experimental animals. Tenidap inhibited calcium ionophore-stimulated prostaglandin D2 synthesis by rat basophilic leukemia cells (COX-1) with an IC50 of 20 nM. In two different in vitro human test systems, tenidap inhibited COX-1 activity more potently than COX-2, although the relative potency ratio (COX-1/COX-2) differed markedly between the two systems. Tenidap inhibited the COX pathway when added to human blood in vitro (IC50, 7.8 mu M) and when administered orally to monkeys, rats and dogs (at 5, 2.5 and 10 mg/kg p.o., respectively) and COX activity measured ex vivo in blood collected 2 to 4 hours post dose. After oral administration to rats, tenidap inhibited carrageenan-induced paw edema with an ED50 of 14 mg/kg and inhibited the glucocorticoid-resistant UV erythema in guinea pigs with an ED50 of 1.4 mg/kg. It retained antiinflammatory activity in adrenalectomized rats indicating that this property is independent of adrenal stimulation. Oral administration of tenidap inhibited the development of adjuvant-induced polyarthritis in the rat and exhibited antinociceptive activity in the murine phenylbenzoquinone and rat acetic acid abdominal constriction tests. These data indicate that tenidap is an effective antiinflammatory and analgesic agent in animal models. These cyclooxygenase-dependent pharmacologic activities do not explain tenidap's disease modifying anti-arthritic properties but add a useful symptom modifying component to its clinical profile.

Effects of antirheumatic agents on cytokines

A review of the literature concerning the effects of traditional antirheumatic drugs on cytokines and the cytokine and anticytokine approaches already used in the therapy of rheumatoid arthritis (RA) is presented. Many antirheumatic drugs are capable of cytokine modulation in vitro. Corticosteroids inhibit the transcription of a broad spectrum of genes including those encoding monocyte, T cell-derived cytokines and several hemopoietic growth factors, whereas drugs such as cyclosporin A and D-penicillamine interfere with T cell activation more specifically by suppressing interleukin 2 (IL-2) production. The in vivo effects of drug therapy on cytokines in RA patients are less well established. Gold compounds reduce circulating IL-6 levels and the expression of monocyte-derived cytokines, such as IL-1, tumor necrosis factor (TNF), and IL-6, in the rheumatoid synovium. Decreases in circulating IL-6, soluble IL-2 (sIL-2R), and TNF receptors and in synovial fluid IL-1 levels have been reported with methotrexate. Reductions in circulating IL-6 and sIL-2R concentrations have also been observed with cyclosporin and corticosteroids, whereas azathioprine reduces IL-6 but not sIL-2R. Studies on sulfasalazine are conflicting and the in vivo effects of D-penicillamine and antimalarials have not been studied yet. Interferon gamma therapy is not effective in RA but may prove a useful antifibrotic for systemic sclerosis. Colony stimulating factors improve the granulocytopenia associated with Felty's syndrome or drug toxicities but can induce arthritis flares and should be reserved to treat infectious complications. Promising results are being obtained with selective antagonism of TNF and IL-1 in RA, and combinations of anticytokine strategies with traditional antirheumatic drugs have been already envisaged. These should preferably be based in a broader knowledge of the effects of antirheumatic agents on the cytokine network.

Tenidap, but not nonsteroidal anti-inflammatory drugs, inhibits T-cell proliferation and cytokine induction

T-lymphocytes are involved in the inflammatory response that occurs in affected joints of patients with rheumatoid arthritis (RA). Some second-line disease modifying anti-rheumatic drugs used in the treatment of patients with RA are known to block T-cell activation. The present study assessed whether tenidap, an investigational anti-rheumatic drug, affects in vitro T-cell responses such as proliferation and cytokine production. It was found that tenidap, in contrast to several nonsteroidal anti-inflammatory drugs, inhibits anti-CD3 or IL-2 driven proliferative responses of cloned human T-cells. Furthermore, tenidap was found to inhibit IFN-gamma production as well as the induction of mRNA encoding IFN-gamma or TNF-alpha. The results indicate that tenidap may exert at least part of its anti-inflammatory activity via inhibition of T-cell function and cytokine production.

Innovative treatment approaches for rheumatoid arthritis. New cyclo-oxygenase and cytokine inhibitors

A need remains for the development of more effective therapies for the treatment of rheumatoid arthritis (both NSAIDs and DMARDs). The NSAIDs remain the cornerstone of symptomatic therapy, but concern remains about their safety, potential for the delay in commencing definitive therapy and theoretical pro-inflammatory effects. Each of the NSAIDs reviewed here do provide an advantage over therapies previously available and should prove to be useful additions to the rheumatologists' therapeutic armament.

Reduction of intracellular pH by tenidap. Involvement of cellular anion transporters in the pH change

Tenidap [5-chloro-2,3-dihydro-3-(hydroxy-2-thienylmethylene)-2-oxo-1H- indole-1-carboxamide], a novel antirheumatic agent, produces a rapid and sustained intracellular acidification when applied to cells in culture. To investigate the mechanism by which this change in ionic homeostasis is achieved, the acidification activities of structural analogs of tenidap were determined, and the movements of [14C]tenidap into and out of cells were explored. The acidification activity of tenidap was enhanced by lowering extracellular pH, suggesting that the free acid species was required for this process. Consistent with this requirement, a non-acidic analog of tenidap did not produce a change in intracellular pH (pHi). In contrast, multihalogenated derivatives of tenidap produced greater changes in pHi than did tenidap, and one analog produced a transient acidification from which the cell recovered; this recovery, however, was blocked by an inhibitor of the Na+/H+ antiporter. Fibroblasts incubated with [14C]tenidap achieved within 5 min a level of cell-associated drug that remained constant during longer incubations. Simultaneous addition of the electrogenic ionophore valinomycin or the P-glycoprotein inhibitor 4-(3,4-dihydro-6,7-dimethoxy-2(1H)-isoquinolinyl)-N-[2-(3,4-dimethoxyphe nyl) ethyl]-6,7-dimethoxy-2-quinazolinamine (CP-100,356) caused a time- and concentration-dependent increase in the level of cell-associated [14C]tenidap; other agents tested did not promote this enhanced cellular accumulation. [14C]Tenidap accumulated by fibroblasts in the presence of CP-100,356 subsequently was released when these cells were placed in a tenidap- and CP-100,356-free medium. Importantly, several agents that are known to inhibit anion transport processes, including alpha-cyano-beta-(1-phenylindol-3-yl) acrylate, 5-nitro-2(3-phenylpropylamino)-benzoic acid, and meclofenamic acid, inhibited efflux of [14C]tenidap. In contrast, ethacrynic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid did not impair the efflux process. Likewise, tenidap analogs that produced a sustained intracellular acidification blocked the efflux of [14C]tenidap, but non-acidifying species did not. These data suggest that movements of tenidap into and/or out of cells is a facilitated process subject to pharmacological intervention. Together, the structural selectivity of the acidification response and the evidence of facilitated transport suggest that the pHi modulating activity of tenidap is dependent on its unique physicochemical properties. Due to the dependence of these physicochemical properties on environmental and cellular conditions, in vivo expression of the acidification activity is likely to occur only within restricted environments that favor this tenidap-induced process.

Acute-phase proteins in osteoarthritis

The joint destruction of osteoarthritis (OA) comprises loss of articular cartilage resulting from an imbalance of enzyme-catalized cartilage breakdown and regeneration. OA is thought to derive from defective chondrocyte metabolism and thus to inherently lack the large-scale systemic response that is the hallmark of rheumatoid arthritis (RA). Because of the apparent absence of systemic inflammation in OA, acute-phase response proteins have not been as extensively studied in OA as they have been in RA. The diagnosis of OA almost always involves radiographic assessment of joint damage, which is useful only after the disease process has been underway for several months. Radiographic evaluation cannot give a good assessment of current disease activity and is a relatively insensitive indicator of prognosis. Cartilage breakdown products can potentially serve as direct surrogate markers of OA disease activity, but have not been extensively used because of their limited sensitivity and the technical difficulties associated with their measurement. Markers of disease activity in RA are indirect and are derived from the acute-phase response, a cycle of temporal changes in cellular and metabolic function. The early part of the acute-phase response involves the local action and production of cytokines such as interleukin-1 (IL-1), tumor necrosis factor (TNF-alpha) and IL-6. In the late acute-phase response, these cytokines can effect many systemic changes, including increased production of acute-phase proteins (APP). Three valuable surrogate markers of disease activity in RA are provided by the acute-phase response: the time-honored erythrocyte sedimentation rate (ESR) and the newer APPs C-reactive protein (CRP) and serum amyloid A (SAA). As in RA, the joint destruction of OA involves IL-1, TNF-alpha, and IL-6; however, OA can be viewed as an indolent stimulus of the later (systemic) acute-phase response. Recent studies of the acute-phase response in OA suggest that the concentrations of CRP and SAA are elevated in OA, but to a lesser extent than in RA. In the future, long-term monitoring of CRP concentrations in the blood may permit the earlier detection and more effective treatment of OA.

Tenidap in rheumatoid arthritis. A 24-week double-blind comparison with hydroxychloroquine-plus-piroxicam, and piroxicam alone

OBJECTIVE

To compare the clinical efficacy, effect on serum C-reactive protein (CRP), serum amyloid A (SAA), and plasma interleukin-6 (IL-6) levels, and safety of tenidap with a combination of hydroxychloroquine-plus-piroxicam, and piroxicam alone, in the treatment of rheumatoid arthritis (RA) patients.

METHODS

A double-blind, randomized, multicenter study in which patients with active RA were treated with tenidap 120 mg/day, hydroxychloroquine 400 mg/day and piroxicam 20 mg/day, or piroxicam alone 20 mg/day, for 24 weeks.

RESULTS

At weeks 12 and 24, tenidap produced greater improvements than piroxicam based on 5 primary efficacy parameters; this improvement showed statistical significance in 4 of the 5 measures at week 12, and in 3 of the 5 measures at week 24. Clinical improvements in the hydroxychloroquine-plus-piroxicam-treated with tenidap. Compared with piroxicam, tenidap was associated with significantly greater reductions in serum CRP concentrations at 4, 12, and 24 weeks, and significantly greater reductions in SAA concentrations at weeks 12 and 24. The decrease in SAA concentrations was also significantly greater at weeks 4 and 24 in the tenidap-treated group than in the hydroxychloroquine-plus-piroxicam-treated group. Significant reductions in plasma IL-6 levels were observed at weeks 4, 12, and 24 within the tenidap group, and at week 24 within the hydroxychloroquine-plus-piroxicam-treated group. The overall occurrence of side effects, including gastrointestinal side effects, was similar in all 3 treatment groups. A small proportion of tenidap-treated patients (6.4%) manifested mild, nonprogressive, reversible proteinuria of presumed renal proximal tubular origin, and 3-4% of patients had elevated transaminase levels.

CONCLUSION

In the treatment of patients with RA, tenidap is as effective as the combination of hydroxychloroquine-plus-piroxicam, and is more effective than piroxicam alone; moreover, tenidap's safety profile is comparable to that observed with piroxicam alone, and with hydroxychloroquine-plus-piroxicam. The clinical response observed in this study, as well as the prompt decreases in acute-phase protein levels of CRP and SAA, and in plasma IL-6 levels, suggest that tenidap represents a new type of antiarthritic medication, with properties similar to, but not identical to, a therapeutic combination of a nonsteroidal antiinflammatory drug with disease-modifying antirheumatic drugs.

Effects of tenidap on canine experimental osteoarthritis. I. Morphologic and metalloprotease analysis

OBJECTIVE

To examine the effects of tenidap and diclofenac on osteoarthritic lesions and metalloprotease activity in experimental osteoarthritis (OA).

METHODS

The anterior cruciate ligament of the right stifle joint of 25 mongrel dogs was sectioned by a stab wound. Seven dogs received no treatment, 6 were treated with oral omeprazole (20 mg/day), another 6 were treated with diclofenac (0.25 mg/kg/twice daily) plus omeprazole (20 mg/day), and 6 received oral tenidap (3 mg/kg/twice daily) plus omeprazole (20 mg/day). The dogs received medication for 8 weeks; all dogs were killed at the end of this period. Eight normal dogs were used as controls. Lesions were evaluated macroscopically for the incidence and size of osteophytes and the area and grade of cartilage erosions on the condyles and plateaus, along with histologic evaluation of the severity of the cartilage lesions and synovial inflammation. Stromelysin and collagenase activities and the collagenase messenger RNA (mRNA) level were measured in cartilage and synovial membrane.

RESULTS

Compared with the untreated or omeprazole-treated OA groups, the dogs treated with tenidap exhibited significant reduction in the incidence (P < or = 0.001) and size (P < or = 0.0001) of osteophytes. Tenidap also significantly decreased the size and grade of cartilage macroscopic lesions, as well as the histologic severity of cartilage lesions on both condyles and plateaus. The histologic severity of synovial inflammatory reaction was also significantly reduced (P < or = 0.003) in the tenidap group. Tenidap markedly decreased stromelysin and collagenase activity in both cartilage (stromelysin P < or = 0.003; collagenase P < or = 0.01) and synovial membrane (stromelysin P < or = 0.003; collagenase P < or = 0.005). Moreover, tenidap also decreased the collagenase mRNA level in cartilage (P < or = 0.005) and synovial membrane (P < or = 0.002). Diclofenac slightly reduced the incidence and size of osteophytes and cartilage lesions, but these changes were not statistically significant. Diclofenac had no effect on the severity of synovial inflammation, metalloprotease activity, or collagenase expression.

CONCLUSION

This study showed that tenidap had a more potent anti-osteoarthritic effect than diclofenac in this model. The effect of the drug in suppressing metalloprotease synthesis, a process known to play a major role in the pathophysiology of osteoarthritic lesions, may explain its mechanism of action.

Cytokines in rheumatic diseases

IL-1 and related cytokines have multiple biologic activities relevant to the rheumatic diseases. In addition to mediating inflammatory and immune responses, these proteins regulate many aspects of connective tissue metabolism. The cytokines interact in complex cascades: because of this, and various technical reasons, the exact role of cytokines in the pathogenesis of rheumatic diseases remains uncertain. However, considerable experimental data suggest that the abnormal regulation of cytokines contributes to such siseases as inflammatory arthritis, systemic lupus erythematosus, scleroderma, and dermatomyositis. Animal models of these diseases have contributed to understanding the role of cytokines in pathogenesis. Furthermore, drugs useful in treating these diseases affect cytokine pathways; some cytokines, their antagonists, or related substances have been used therapeutically to treat rheumatic diseases. The therapeutic use of these agents will likely increase as knowledge about the role of cytokines in the pathogenesis of rheumatic diseases expands.