Reduced thiopurine methyltransferase activity and development of side effects of azathioprine treatment in patients with rheumatoid arthritis.

OBJECTIVE: To investigate thiopurine enzyme activities for their possible value in predicting the development of azathioprine (AZA)-related toxicity in patients with rheumatoid arthritis (RA). METHODS: Patients with longstanding RA (n = 33) were enrolled in a study of treatment with AZA. Before the initiation of AZA treatment and at months 1 and 6 of treatment, we measured activities of the purine key enzymes hypoxanthine guanine phosphoribosyltransferase, 5'-nucleotidase, purine nucleoside phosphorylase, and thiopurine methyltransferase (TPMT). Controls included patients with early RA (n = 24) and healthy volunteers (n = 42). RESULTS: Fourteen of the 33 patients rapidly developed severe side effects, most frequently gastrointestinal (GI) intolerance. Compared with the other groups, the group with adverse effects had significantly lower TPMT activities (P = 0.004). Seven of 8 patients with reduced ("intermediate") baseline TPMT levels developed toxicity, resulting in a significant relationship (P = 0.005) between toxicity and "intermediate" TPMT activity. Compared with "high" activity, baseline intermediate TPMT activity gave a relative risk of 3.1 (95% confidence interval 1.6-6.2) for the development of severe toxicity with AZA treatment. CONCLUSION: In RA patients, inherited intermediate TPMT activity seems predictive for the development of severe side effects of AZA. Clinicians should consider measuring TPMT prior to treatment initiation to improve the safety of AZA use. We hypothesize that GI intolerance may also be related to a thiopurine metabolic imbalance.

The moderate intestinal side effects of auranofin do not require prophylactic therapy with a bulkforming agent. Dutch Ridaura Study Group.

Incidences of diarrhoea and loose stools are reported up to 50% in patients starting treatment with auranofin. Moreover, +/-4% of patients discontinue treatment because of severe diarrhoea. We investigated whether a water binding agent would diminish the incidence of loose stools and diarrhoea. Endpoints were the patient's general impression of the quality of stools and a daily assessment of stool's frequency/consistency and adverse events. Secondly, some disease activity parameters were used to evaluate whether the bulkforming agent influences the efficacy of auranofin. In this study 269 patients suffering from Rheumatoid Arthritis (RA) were treated with auranofin 6 mgr daily for a period of six months. Simultaneously the patients were randomly treated with either a bulkforming agent (Volcolon: psyllium fibres) or placebo. Results show a 15% incidence of loose stools and diarrhoea during treatment with auranofin. During the treatment period the patients' general impression of defecation consistency showed a shift to softer types. The changes in defecation consistency was not significantly different between groups (Intention-to-treat analysis: C2=4.01; p=0.13). Also, the percentage of patients experiencing episodes of diarrhoea (reported as an adverse experience) was not different (14% of the patients treated with bulkformer versus 15% with placebo). During the first month 7% (n=5) of placebo treated patients reported short episodes of watery stools versus none in the bulkformer treated group. The percentage of days with loose or watery stools, reported on the diary cards, was consistently lower in bulkformer treated patients. Both groups improved equally with respect to disease activity parameters. Sixty-eight percent of patients continued auranofin treatment after the study period. In conclusion, these data do not support adjuvant therapy with a bulkforming agent on initiation of auranofin therapy. The overall low incidence of loose stools and diarrhoea suggests that a dose increase to 9 mgr daily is an option to enhance the efficacy of auranofin treatment.

Methotrexate versus azathioprine in the treatment of rheumatoid arthritis. A forty-eight-week randomized, double-blind trial.

We conducted a double-blind, randomized trial comparing azathioprine (AZA) and methotrexate (MTX) in the treatment of patients with rheumatoid arthritis in whom parenteral gold and/or D-penicillamine treatment had been unsuccessful. Patients were randomly assigned to receive either AZA (100 mg daily) or oral MTX (7.5 mg weekly). After 8 weeks, the dosage was increased depending on the clinical improvement. Sixty-four patients were followed up for 48 weeks (33 AZA, 31 MTX). Comparison of values at week 24 with baseline values revealed significant improvement in 12 of 13 disease variables in the MTX group and in 6 of 13 in the AZA group. Comparison between the 2 treatment groups at 24 weeks, by area-under-the-curve analysis, showed significantly more improvement in the MTX group in terms of the swollen joint count, pain score, erythrocyte sedimentation rate, C-reactive protein level, hemoglobin level, thrombocyte level, and disease activity score. A significant overall clinical improvement (disease activity score) was found in 7 of 20 patients treated with AZA and 18 of 30 patients treated with MTX after 24 weeks of therapy, and in 6 of 12 AZA-treated patients and 19 of 25 MTX-treated patients after 48 weeks. The number of withdrawals due to side effects was significantly higher in the AZA group. After 48 weeks, only 12 patients from the AZA group (36%), but 25 from the MTX group (81%), were still using the initial drug. These results demonstrate MTX to be superior to AZA in the treatment of rheumatoid arthritis, with a more rapid clinical improvement which is sustained after 1 year, accompanied by a lower rate of serious adverse reactions.

Cricoarytenoid arthritis may be a case of emergency.

Cricoarytenoid arthritis is a frequent complication of rheumatoid arthritis. In most cases it is an insidious, progressive disorder which does not produce early symptoms. A bilateral fixation can lead to a considerable stenosis; exertional dyspnoea, however, may not be noted because mobility of most patients is restricted. We report a case of severely symptomatic cricoarytenoid arthritis in a women known to have myasthenia gravis and rheumatoid arthritis. Initially exacerbation of the myasthenia gravis, leading to severe inspiratory insuffiency was suspected. On indirect laryngoscopy, however, the correct diagnosis was made. Early diagnosis might have prevented an emergency in our patient.

99mTc-pertechnetate uptake measurement in the rabbit knee-joint. II. Kinetics of 99mTcO-4 in normal and arthritic rabbit knee-joints.

The kinetics of 99mTechnetium pertechnetate (99mTcO-4) in the rabbit knee-joint were studied by external counting of the radio-isotope after intravenous injection. We studied joints with antigen-induced arthritis in the acute and chronic phase of joint inflammation as well as non-inflamed joints. In both inflamed and non-inflamed joints, a rapid increase in radioactivity was followed by a plateau lasting for at least one hour. The time needed to reach 95% of the plateau count rate (tp) was significantly increased in inflamed as compared with non-inflamed knee-joints. Moreover, tp values were significantly higher in acutely than in chronically inflamed joints. No correlation was found between 99mTcO1 uptake and tp values. The study of kinetics of 99mTcO-4 in the rabbit knee-joint provides information additional to quantitation of inflammation by 99mTcO-1 uptake measurements, since kinetic data characterize the type of joint inflammation.

Antigen handling in antigen-induced arthritis in mice: an autoradiographic and immunofluorescence study using whole joint sections.

Antigen localization after intraarticular antigen injection was studied in immune and nonimmune mice using autoradiographic and immunofluorescence techniques on whole joint sections. After intraarticular injection of radiolabeled methylated bovine serum albumin (125I-mBSA) in immune mice, labeling in the synovium and synovial exudate diminished rapidly, apart from some deposits in fibrinlike material present in the joint cavity. Long-term antigen retention was found in avascular and hypovascular structures lining the joint cavity, albeit not along the whole surface; eg, labeling remained present at the edges of the femoral condyle hyaline cartilage but not at the central weight-bearing region; long-term retention at ligaments was only found at the insertion sites. Immunofluorescence data in immune animals showed antigen retention together with the presence of immunoglobulins and complement, indicating that antigen is retained at least in part in the form of immune complexes. Nonimmune mice showed even higher long-term antigen retention than immune animals, probably related to physico-chemical properties of the antigen enabling nonimmune binding to articular structures, but also indicating that the presence of joint inflammation in the immune animals enhances antigen clearance. Histologic examination of the ligaments and patellar cartilage of immune mice did reveal that long-term antigen retention was not anatomically related to nearby inflammation or to local tissue damage. The importance of long-term antigen retention for the chronicity of arthritis may lie in the leakage of small amounts of this antigen to joint compartments where it does behave as an inflammatory stimulus; it may further be that it renders the joint a specifically hypersensitive area.

Antigen-induced arthritis: inflammation and antigen handling after two different doses of intra-articularly injected antigen.

We studied (i) the inflammatory response induced by intra-articular (i.a.) injection of 2.5 and 0.5 mg 125I-labelled bovine serum albumin (125I-BSA) into the paired knee joints of rabbits immunized with BSA in Freund's complete adjuvant, and (ii) handling of these different doses of antigen by means of regular external radioactivity measurements. The joint inflammation was quantified by 99mTechnetium pertechnetate uptake measurements. More severe arthritis was seen in the 2.5 mg BSA-injected than in the paired 0.5 mg BSA-injected knee, both in the early and in the late phase of antigen-induced arthritis. External radioactivity measurements showed enhanced disappearance of radioactivity from the 2.5 mg 125I-BSA challenged knee joint, resulting in lower percentual retention of the dose injected than in the 0.5 mg injected knee joint. However the calculated absolute amount of long term retained BSA in the 2.5 mg BSA injected knee, 4 weeks after i.a. injection, was still about 2.8 times the quantity of BSA retained in the 0.5 mg BSA-injected paired knee joint. These data indicate that the severity of both the early and late phase of antigen-induced arthritis is i.a. antigen dose-dependent and, in addition, suggest that handling of i.a. antigen depends in part on the severity of joint inflammation.

Side-effects of azathioprine treatment in rheumatoid arthritis: analysis of 10 years of experience.

Our experience with azathioprine in the treatment of rheumatoid arthritis covers ten years, during which 91 rheumatoid patients (66 female and 25 male) received this drug, with a median treatment period of 36 months. Total follow-up experience, during and after treatment, was 399 person years. Twelve patients died. The principal causes of death were malignant neoplasm (six patients) and cardiovascular diseases (three patients). The mortality in our patients was compared to that of the general Dutch population by the Standardised Mortality Ratio (SMR). In the male patient group a significant excess of both total mortality and mortality from malignancy was observed. The female patients showed no differences from the general population. In this follow-up study, no lymphoreticular tumours occurred during or after azathioprine therapy.

Antigen induced arthritis: antigen handling and chronicity of joint inflammation.

Data are summarized on antigen handling by the joint and the relevance of antigen retention for the chronicity of joint inflammation. Antigen retention may occur at collagenous structures of the joint, when antibodies are present in these tissues or simply when the charge of an antigen favours nonimmune binding at the highly charged collagenous tissues. Antigen retention will change with alterations in antibody load and fixed charge density of these tissues. Longterm retained antigen seems not inflammatory at the retention sites, but its importance for the chronicity of joint inflammation may lie in the continuous leakage of small amounts to other compartments, where it does behave as an inflammatory stimulus, thereby rendering the joint specifically hypersensitive to antigen. Such a joint reacts to minute amounts of antigen in the circulation leading to exacerbation of smouldering joint inflammation.

Antigen handling in antigen-induced joint inflammation: kinetics of a second intra-articularly injected dose of antigen in an already established antigen-induced joint inflammation.

The fate of a second intra-articularly (i.a.) injected dose of bovine serum albumin (BSA) in an already established BSA-induced knee-joint inflammation was compared with that of a paired first arthritis-inducing injection of the same dose of BSA into the contralateral knee of immunized rabbits. External counting of i.a. radiolabelled BSA indicated more rapid initial elimination but approximately two-fold increase in long-term retention of BSA after a second i.a. injection as compared with a first one. Direct counting of dissected joint structures confirmed these data and localized the retained BSA predominantly in hyaline articular cartilage, menisci and ligaments, both after a first and after a second injection. Since the protocol used in these studies per se excluded systemic factors as possible determinants of the difference in antigen retention observed, local alterations in the already inflamed joint caused this difference. Control studies indicated that both humoral immune factors and non-specific inflammatory changes within the chronically inflamed joint determine the phenomenon. Local alterations in an immune-induced chronically-inflamed joint increase its antigen-binding capacity, a mechanism of possible relevance to the chronic course and the occurrence of exacerbations characteristic of some forms of human arthritis.

Antigen-induced and zymosan-induced arthritis in mice: studies on in vivo cartilage proteoglycan synthesis and chondrocyte death.

The influence of joint inflammation on patellar hyaline articular cartilage was studied in mice. Antigen-induced and zymosan-induced arthritis were used as models for immunologically and non-immunologically induced joint inflammation. The contribution of newly formed proteoglycan to the cartilage proteoglycan content, as measured by labelling of the cartilage after i.v. administration of 35S-sulphate, was decreased in parallel with the severity of inflammation during both zymosan-induced and antigen-induced arthritis. The decreased 35S content of the cartilage was due to inhibition of synthesis rather than breakdown of newly synthesized proteoglycan, since no accelerated release of 35S from arthritic cartilage could be demonstrated in vitro. Antigen-induced arthritis was associated with progressive chondrocyte damage. Loss of chondrocytes was consistently found in the central part of the patella, without nearby presence of pannus. It would appear that, in addition to enzymatic breakdown of cartilage, other phenomena are important in cartilage destruction: inhibition of proteoglycan synthesis and chondrocyte death, apparently unrelated to pannus formation.

Antigen-induced arthritis: inflammation and antigen handling.

Data are summarized indicating that the degree and duration of antigen induced arthritis (AIA) influences handling of intra-articular (i.a.) antigen. Long term antigen retention was less in chronic as compared with transient joint inflammation, whereas i.a. antigen was cleared more rapidly from the joint in severe than in moderate AIA. In addition, the presence of ungoing AIA enhances initial elimination of i.a. injected antigen from the joint.

99mTc-pertechnetate uptake measurement in the rabbit knee-joint.

We studied 99mTc- pertechnetate (TcO4) uptake measurements in rabbit knee joints. Results in non-inflamed rabbit knee joints indicated that the difference between paired measurements of both knees (R-L difference) was an accurate measure, independent of age and weight. In the early phase of unilateral antigen-induced arthritis, there was a particularly close correlation between R-L difference values and clinical scores of inflammation, reflecting an acute type of inflammation. Data obtained after the early phase of arthritis suggested that R-L difference measurements provide a more sensitive measure of inflammation than clinical scores. 99mTcO4 uptake measurements can reliably be used to detect and quantitate joint inflammation in animals as small as rabbits.

Proliferative lesion of arthritis: a target for therapy?

The term proliferative lesion refers to the increase in the amount of connective tissue and in the number of small blood vessels and mesenchymal cells with both phagocytic and synthetic functions, characterizing the rheumatoid synovium. This type of lesion is probably responsible for most of the joint destruction and synovial tissue fibrosis seen in this disease. In vitro data indicate that not only factors inducing bone resorption, for instance osteoclast activating factor and prostoglandins, but also connective tissue-degrading enzymes, can be produced locally in the joint, which suggests that these factors play a role in the destruction of articular structures. D-Penicillamine suppresses the immuno-inflammatory process of rheumatoid arthritis, which indirectly may lead to a depression of the stimuli perpetuating the proliferative lesion. As yet, there are no unequivocal clinical data indicating that D-Penicillamine has a direct suppressive effect on the proliferative lesion.