Radiological and clinical results of longterm treatment of rheumatoid arthritis with methotrexate and azathioprine.

OBJECTIVE: To study whether the reported superior effect of methotrexate (MTX) compared to azathioprine (AZA) in retarding radiologic progression after one year in rheumatoid arthritis was sustained at 2 and 4 years. METHODS: All 64 patients enrolled in the original randomized double blind study were invited for an open extension of followup to 4 years including 4-monthly clinical and laboratory assessments and radiographs of hands, wrists, and feet at 2 and 4 years. RESULTS: After 4 years, 18 patients (58%) from the MTX group and 7 patients (21%) from the AZA group continued the initial study drug. During followup more patients (n = 21) switched from AZA to MTX than vice versa (n = 5). In an intention-to-treat analysis improvement of clinical and laboratory variables at 4 years was more pronounced in the MTX group. Mean radiologic scores increased in both treatment groups during followup. According to an intention-to-treat analysis increase in erosion score at one and 2 years in the MTX group was significantly lower than in the AZA group: after one year MTX group 1.8 versus AZA group 5.3 (p = 0.002); after 2 years MTX 3.5 versus AZA 6.5 (p = 0.05). After 4 years there was a trend toward less progression in the MTX group: MTX 6.8 versus AZA 10.8 (p = 0.09). For the total score, progression in the MTX group was less after one and 2 years. After 4 years marked radiologic progression was observed more often in the AZA group. CONCLUSION: Drug continuation after 4 years of followup was better for MTX than for AZA. In an intention-to-treat analysis the beneficial effect of MTX on radiologic progression compared with AZA was sustained after 2 years of followup. Thereafter differences between treatment groups leveled off, probably mainly due to the greater number of switches from AZA to MTX than vice versa.

Reduced purine 5'-nucleotidase activity in lymphocytes of patients with systemic lupus erythematosus: results of a pilot study.

OBJECTIVE: To investigate purine metabolism in patients with systemic lupus erythematosus (SLE) for possible abnormalities that might be related to their overall impaired immune function. METHODS: This pilot study included 17 patients with SLE (2 men, 15 women). Enzyme activities of the purine enzymes 5'-nucleotidase (5'NT), purine nucleoside phosphorylase (PNP), and hypoxanthine-guanine-phosphoribosyltransferase (HGPRT) were measured in peripheral blood mononuclear cells (PBMC) and also in fractions of T cells (differentiation antigen CD3+) (n = 12) and B cells (CD19+) (n = 9). The activity of the thiopurine enzyme thiopurine-methyltransferase (TPMT) was measured in red cell lysate. Routine blood tests and indices of disease activity were measured as well. Results were compared with those of healthy volunteers. RESULTS: Compared with their controls, the female SLE patients had a more than 50% reduced activity of 5'NT in the T cell fraction (p = 0.001) and in PBMC (p < 0.000). 5'NT activity was also lower in B cells, but this was not statistically significant. Enzyme activities did not correlate with indices of disease activity, disease duration or the B cell/T cell ratio and no influence of medication was found. CONCLUSION: Reduced lymphocyte 5'NT activity is a novel finding in SLE. These results indicate that purine metabolism in SLE may be disturbed. Consequences of a low 5'NT activity may be an intracellular accumulation of (deoxy)purine nucleotides and a reduction of adenosine production. It is hypothesised that these factors may play a part in the overall impaired immune function and in the chronicity of inflammation in SLE.

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.

Molecular heterogeneity of second and fourth components of complement and their genes in systemic sclerosis and association of HLA alleles A1, B8 and DR3 with limited and DR5 with diffuse systemic sclerosis.

Deficiency of the complement component C4 at the functional, protein and gene level and deficiency of complement component C2 at the functional level were investigated and HLA analysis was performed on patients with limited and diffuse systemic sclerosis (SSc). One of the patients with limited SSc (n = 15) had subnormal C4, 1 subnormal C2 and 1 subnormal C4 and C2 activities; the latter patient had HLA alleles A11;B35;Dw1 associated with type II C2 deficiency and therefore most likely had a defect at the C2 locus. One of the patients with diffuse SSC (n = 12) had subnormal C4 and 1 subnormal C4 and C2 activities. C2 deficiencies in patients other than the one with the haplotype associated with C2 deficiency appeared not to be determined by the gene at the C2 locus. The incidence of partial C2 deficiency in a normal Caucasian population is reported to be 16 in 10,000, and that of partial C4 deficiency also appears to be very low. The percentages of C4A*Q0 and C4B*Q0 alleles in normal controls (n = 45) were within the reported range. Seven patients with limited SSc (n = 14) had one or two C4A*Q0 alleles and 2 with diffuse SSc (n = 13) had one C4A*Q0 allele. Thus, the incidence of C4A*Q0 was higher than normal in limited SSc and within the normal range in diffuse SSc. The two-sided Fisher's exact test applied on these data revealed that the association of C4A*Q0 with limited SSc did not reach a significant level (p = 0.10). Two of the 3 patients with limited SSc, who had two C4A*Q0 alleles, carried a heterozygous C4A-21-hydroxylase A (OHA) gene segment deletion as detected by Southern blotting. There was no correlation between the subnormal activity of C4 and the occurrence of one or two C4A*Q0 (and C4A-21-OHA segment deletion). HLA alleles A1, B8 and DR3 (p = 0.002) were associated with limited SSc (n = 23) and DR5(w11) (p = 0.018) with diffuse SSc (n = 17).

Purine enzyme activities in recent onset rheumatoid arthritis: are there differences between patients and healthy controls?

OBJECTIVE: Purine enzyme activities may predict the effectiveness of azathioprine treatment and be associated with increased deaths from infectious diseases. In rheumatoid arthritis, patients show variable responses to azathioprine and a higher percentage of death is caused by infections. The aim of the study was to investigate possible rheumatoid arthritis associated abnormalities of purine enzyme activities by measuring several of these enzymes in patients with recent onset rheumatoid arthritis before treatment with disease modifying antirheumatic drugs or prednisone. METHODS: 23 patients with recent onset rheumatoid arthritis and 28 healthy controls were studied. Activities of the enzymes 5'-nucleotidase, purine nucleoside phosphorylase (PNP), hypoxanthine guanine phosphoribosyltransferase (HGPRT), and thiopurine methyltransferase (TPMT) were measured. Assessment of disease activity and blood sampling for routine measurements and HLA typing were done simultaneously. RESULTS: Purine enzyme activities did not differ between patients and healthy controls. Enzyme activities had no significant relations with indices of disease activity or rheumatoid factor titre or with the rheumatoid arthritis associated HLA types. Activity of 5'nucleotidase decreased with age (P < or = 0.05) and was lower by about 27% (P = 0.007) in males than in females. CONCLUSIONS: In rheumatoid arthritis patients, neither the variability in azathioprine effectiveness nor the increased death rate from infections can be explained by pre-existing abnormalities in the activities of the purine enzymes 5'-nucleotidase, PNP, HGPRT, or TPMT at an early stage of the disease, before disease modifying antirheumatic drugs or prednisone treatment. Besides adjustment for age, results of studies involving purine 5' nucleotidase activity should also be adjusted for sex.

Comparison of methotrexate with placebo in the treatment of systemic sclerosis: a 24 week randomized double-blind trial, followed by a 24 week observational trial.

In this study, methotrexate (MTX) was compared with placebo in the treatment of systemic sclerosis (scleroderma, SSc) in a 24 week randomized double-blind trial, followed by an observational trial of 24 weeks duration. Twenty-nine scleroderma patients were allocated to receive weekly injections of either 15 mg MTX or placebo. Patients who responded favourably after 24 weeks continued with the same regimen for a further 24 weeks; those who showed a poor response on placebo were allocated to further treatment with 15 mg MTX weekly, and those who responded poorly to treatment with 15 mg MTX had their doses increased to 25 mg. A favourable response was defined as an improvement of total skin score (TSS) by > or = 30%, of single breath diffusion capacity (DLCO) by > or = 15%, or of the score on a visual analogue scale of general well-being (VAS) by > or = 30%, provided that such improvements were not accompanied by persistent digital ulcerations or worsening of DLCO > or = 15%. Seventeen patients were allocated to MTX treatment and 12 to treatment with placebo. After 24 weeks, a significantly larger number of patients receiving MTX (n = 8, 53%) who completed the first 24 weeks of the study had responded favourably compared to patients receiving placebo (n = 1, 10%, P = 0.03). Comparison of separate variables between the two treatment groups by intention-to-treat analysis at week 24 showed improvement in the MTX group of TSS (P = 0.06) and creatinine clearance (P = 0.07). At week 48, 13 patients received MTX from the start of the study and nine during 24 weeks. From these 22 patients, 15(68%) responded favourably and compared with the start of the study they showed significant improvement of TSS (P = 0.04), VAS (P = 0.02), grip strength of the right hand (P = 0.02) and ESR (P = 0.01). Although the number of patients enrolled in this study is small, these results suggest that in a group of patients with active systemic sclerosis, low-dose MTX seems to be more effective than placebo according to pre-defined response criteria.

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.

Effect of methotrexate alone or in combination with sulphasalazine on the production and circulating concentrations of cytokines and their antagonists. Longitudinal evaluation in patients with rheumatoid arthritis.

In a recent study from our group, the combination of methotrexate and sulphasalazine (MTX + SASP) seemed superior to MTX alone in the treatment of rheumatoid arthritis (RA). To assess the impact of these therapies on the cytokine cascade, the in vitro production and circulating concentrations of several cytokines and endogenous cytokine antagonists were measured in 30 healthy controls and longitudinally in a subset of 26 patients enrolled in this study. Compared to controls, RA patients had significantly higher circulating concentrations of interleukin-6 (IL-6), soluble receptors for tumour necrosis factor (sTNFR), soluble receptors for interleukin-2 (sIL-2R) and interleukin-1 receptor antagonists (IL-1RA), and their peripheral blood mononuclear cells (PBMNC) showed a higher spontaneous production of interleukin-1 beta (IL-1 beta), tumour necrosis factor alpha (TNF alpha) and IL-1RA (both secreted and cell-associated) and a higher stimulated production of cell-associated TNF alpha, IL-1RA and (to a lesser extent) IL-1 beta. Treatment with MTX alone (n = 12) or combined with SASP (n = 14), resulted in significant reductions of circulating IL-6 and sIL-2R but did not alter IL-1 beta, TNF alpha or IL-1RA concentrations. Decreases in circulating levels of sTNFR and in the in vitro production of cell-associated IL-1 beta and IL-1RA after stimulation were only observed in patients treated with MTX + SASP. The concentrations of IL-1RA and sTNFR in the circulation exceeded moderately those of IL-1 beta and TNF alpha but this is probably insufficient to block IL-1 and TNF alpha activity. In conclusion, therapy with MTX alone or with SASP modulates IL-6 and sIL-2R concentrations in RA. Decreased production of IL-1 beta and IL-1RA and circulating sTNFR levels were only observed during therapy with MTX + SASP. Whether this relates to the better clinical effect observed with the combination therapy remains to be investigated. Circulating levels of IL-6, sIL-2R and sTNFR seem useful markers of disease activity in RA.

Infections during low-dose methotrexate treatment in rheumatoid arthritis.

We studied the infection rate in patients with rheumatoid arthritis (RA) treated with low-dose methotrexate (MTX) in a 6-year open prospective study and in a 12-month randomized double blind trial comparing MTX with azathioprine (AZA) that was followed by a 3-year open prospective study. The literature on infections during low dose MTX in RA was reviewed. We also did a search for therapy-related opportunistic infections in RA and in MTX-treated psoriasis and psoriatic arthropathy patients. In our studies the infection rate during MTX treatment was higher in severe RA than in moderate RA. In severe RA there were often 2 infections simultaneously. The majority of the infections occurred in the first 1.5 years of treatment. There was no difference in the infection rate of MTX and AZA in the comparative trial. In the literature the infection rate was highest in short-term double-blind studies. Opportunistic infections are increasingly reported in RA treated with MTX and rarely with AZA, cyclosporine A, and cyclophosphamide or in MTX treated psoriasis and psoriatic arthropathy. In RA it appears that the initial period of treatment with MTX is the most vulnerable phase for infections, with the exception of opportunistic infections, which are not limited to a certain treatment period. Probably there are more MTX-associated infections in severe RA than in moderate RA.

Purine enzyme activities in peripheral blood mononuclear cells: comparison of a new non-radiochemical high-performance liquid chromatography procedure and a radiochemical thin-layer chromatography procedure.

Purine enzyme activities are usually assayed by radiochemical procedures and often TLC is part of the separation method. In screening patients with rheumatic diseases, these procedures have shown disadvantages like a relatively large coefficient of variation (C.V.) and time-instability. We describe a non-radiochemical reversed-phase HPLC micro-method with UV detection for measurement of activities of purine 5'-nucleotidase (5'NT; EC 3.1.3.5), purine nucleoside phosphorylase (PNP; EC 2.4.2.1) and hypoxanthine guanine phosphoribosyltransferase (HGPRT; EC 2.4.2.8) in human peripheral blood mononuclear cells (PBMC). The HPLC procedure is compared with the radiochemical TLC procedure by testing both with a 5'NT and a PNP assay. Reproducibility is tested with 14 healthy controls in each procedure. Short-term and long-term time-stability is tested by comparing enzyme activities measured immediately after preparation of the PBMC (week 0) with those found after freezing and storage at -20 degrees C for a maximum of 10 weeks. The HPLC procedure is preferable to the radiochemical TLC procedure because it shows significantly better reproducibility and better time-stability and in addition is non-radiochemical and less time-consuming.

Azathioprine-related bone marrow toxicity and low activities of purine enzymes in patients with rheumatoid arthritis.

OBJECTIVE: Azathioprine (AZA) metabolism largely parallels the endogenous purine pathways. To date, thiopurine methyltransferase (TPMT) deficiency has been reported as a cause of AZA-related bone marrow toxicity in 1 patient with rheumatoid arthritis (RA). We therefore studied purine enzyme activities in 3 patients with RA who experienced AZA-related bone marrow toxicity. METHODS: Lymphocyte activity of purine nucleoside phosphorylase and 5'-nucleotidase (5NT) and erythrocyte activity of TPMT, key enzymes in thiopurine catabolism, were measured in 3 RA patients who had experienced AZA-related bone marrow toxicity and in 16 RA patients without signs of toxicity despite at least 6 months of treatment with AZA. RESULTS: Two patients with AZA-related bone marrow toxicity were found to have a TPMT deficiency, 1 partial and 1 total. In the third patient, 5NT activity was found to be well below the lowest level observed in the control subjects. CONCLUSION: All 3 patients with severe AZA-related bone marrow toxicity had abnormal purine enzyme activities. Deficiency of purine enzymes, including TPMT and 5NT, may be a cause of AZA-related bone marrow toxicity in patients with RA.

Purine enzymes in rheumatoid arthritis. A clue to the prediction of the response to azathioprine? Review and hypothesis.

Azathioprine (AZA), a purine analog, is an effective agent in the treatment of rheumatoid arthritis (RA), but variability of response and sometimes life-threatening side effects limit its use (1). The metabolism of AZA parallels the endogenous purine pathways. In this paper we review some general aspects of purine and thiopurine metabolism, their relation with various disease states and current knowledge of the influence of purine enzymes on the effects of AZA treatment. We suggest that intracellular purine enzyme activities determine the response to AZA treatment in patients with RA, and that a role for purine enzyme activities in the ethiopathogenesis of RA should be considered.

Antiperinuclear factor and disease activity in rheumatoid arthritis. Longitudinal evaluation during methotrexate and azathioprine therapy.

OBJECTIVE: To study the correlation between antiperinuclear factor (APF) titer and disease activity variables in patients with rheumatoid arthritis (RA) treated with methotrexate (MTX) or azathioprine (AZA) and to investigate whether changes are dependent on the drug used. METHODS: Serial measurements of APF titers (2-fold dilutions) and disease activity variables in a 48-week double blind trial comparing MTX and AZA in 64 patients with RA. APF titers at baseline and during followup, and correlations between APF titers and disease activity variables and their changes from baseline were studied in the patient group as a whole and in the 2 treatment groups. RESULTS: The prevalence of the APF at baseline in the MTX group and in the AZA group with undiluted serum was 15/31 (48%) and 19/33 (58%), respectively. With serum diluted 1:10 this was about 25% higher. The APF titer ranged from 1/10 to 1/640. No sustained changes in APF titers were observed during followup. Statistically significant correlations were found between APF titers and 2 of the 4 disease activity variables, as well as for their changes from baseline at some time points and were most pronounced in the AZA group. However, no consistent correlation between APF titers and disease activity variables could be established. APF changed from negative to positive during followup in 4 patients (6.3%) and from positive to negative in 4 (6.3%). Changes in APF titer between 2 consecutive measuring points did not exceed 2 dilution steps. CONCLUSION: The APF titer showed no sustained change during the followup period. There was no consistent correlation between APF titer and disease activity variables. We conclude that serial measurements of the APF in longitudinal studies do not give additional information.