R J van de Stadt

Evaluation of bone mineral density, bone metabolism, osteoprotegerin and receptor activator of the NFκB ligand serum levels during treatment with infliximab in patients with rheumatoid arthritis

Objectives: To examine whether treatment with anti-tumour necrosis factor (TNF) α prevents loss of bone mineral density (BMD) at the spine and hip (generalised) and in the hands (local) of patients with rheumatoid arthritis, and to study the changes in markers of bone metabolism, including receptor activator of the NFκB ligand (RANKL) and osteoprotegerin (OPG), during anti-TNF treatment. Patients and methods: 102 patients with active rheumatoid arthritis, who were treated with infliximab during 1 year, were included in this open cohort study. The BMD of the spine and hip (dual x ray absorptiometry) and hands dual x ray radiogrammetry was measured before the start of treatment and after 1 year. Changes in osteocalcin formation, β-isomerised carboxy terminal telopeptide of type 1 collagen (β-CTx, resorption), RANKL and OPG were determined at 0, 14, 30 and 46 weeks. Results: The BMD of the spine and hip was unchanged during treatment with infliximab, whereas BMD of the hand decreased significantly by 0.8% (p<0.01). The BMD of the hip in patients with a good European League Against Rheumatism response showed a favourable change compared with patients not achieving such a response. Serum β-CTx and RANKL were both considerably decreased compared with baseline at all time points. The decrease in β-CTx was associated with the decrease in Disease Activity Score of 28 joints and C reactive protein during the 0–14 weeks interval. Conclusion: In patients with rheumatoid arthritis treated with infliximab, spine and hip bone loss is arrested, whereas metacarpal cortical hand bone loss is not stopped. The outcome of the study also supports a relationship between clinical response, in terms of reduced inflammatory activity, and changes in bone loss of the spine, hip and hands.

Lipids and inflammation: serial measurements of the lipid profile of blood donors who later developed rheumatoid arthritis.

Background: Rheumatoid arthritis is characterised by inflammation and an increased cardiovascular risk. It was recently shown that active early rheumatoid arthritis is associated with dyslipidaemia, which may partially explain the enhanced cardiovascular risk. However, it is unknown when this dyslipidaemia starts. Objective: To investigate the progression of the lipid profile over time and the influence of inflammatory parameters on this lipid profile, in people who later developed rheumatoid arthritis. Methods: Levels of total cholesterol, high-density lipoprotein cholesterol (HDLc), triglycerides, apolipoprotein AI (apo AI), apolipoprotein B (apo B) and lipoprotein(a) (Lp(a)) were determined in 1078 stored, deep-frozen, serial blood bank samples, collected between 1984 and 1999, of 79 blood donors who later developed rheumatoid arthritis. These samples were compared with 1071 control samples of unselected blood donors, matched for age, sex and storage time. Results: Samples of patients who later developed rheumatoid arthritis showed, on average, 4% higher total cholesterol, 9% lower HDLc, 17% higher triglyceride and 6% higher apo B levels than matched controls (p⩽0.05). The magnitude of the differences in lipid levels between groups, explained by C reactive protein (CRP), was limited. For example, only 3.6% of the difference in HDLc levels between the groups was explained by the CRP concentrations. Conclusion: Patients who later develop rheumatoid arthritis have a considerably more atherogenic lipid profile than matched blood donors at least 10 years before onset of symptoms. As inflammation only marginally explains the differences between the two groups, a modulating effect of lipids on inflammatory processes is hypothesised.

The interaction between the mitochondrial ATPase (F1) and the ATPase inhibitor

1. The naturally occurring mitochondrial ATPase inhibitor inhibits the mitochondrial ATPase (F1) non-competitively. 2. The interaction between inhibitor and inhibitor-depleted F1 or submitochondrial particles is diminished when the ratio of ATP/ADP is low or when energy is generated by substrate oxidation. 3. The dissociation of the inhibitor from coupled Mg-ATP particles is promoted when substrates are being oxidized. This results in the appearance of a large uncoupler-stimulated ATPase activity. Activation of the uncoupler-stimulated ATPase activity is also achieved by incubation of the particles with ADP. 4. The ATPase activity of Mg-ATP particles is determined by the turnover capacity of F1. When endogenous inhibitor is removed, energy dissipation becomes the rate-limiting step. This energy dissipation can be activated by an uncoupler. 5. Evidence is presented for the existence of a non-inhibited intermediate F1-inhibitor complex.

Tight binding of adenine nucleotides to beef-heart mitochondrial ATPase

Abstract Mitochondrial ATPase (F1) isolated from beef heart contains 5 moles of tightly bound adenine nucleotide per mole of enzyme—3 moles ATP and 2 moles ADP. These are retained after repeated precipitation of the enzyme with (NH4)2SO4 and are only partially removed by treating the enzyme with activated charcoal or filtering through Sephadex. Cold denaturation, however, causes complete release of the adenine nucleotides from the protein. The exchange of the bound nucleotides with added nucleotides is slow.

Simultaneous development of acute phase response and autoantibodies in preclinical rheumatoid arthritis

Objective: To investigate the temporal relationship between onset of inflammation (as measured by secretory phospholipase A2 (sPLA2) and C reactive protein (CRP)) and the presence of autoantibodies (IgM rheumatoid factor (IgM RF) and antibodies against citrullinated peptides (anti-CCP)) in the preclinical phase of rheumatoid arthritis (RA). Methods: For 79 patients with RA who had been blood donors before the onset of disease, a median of 13 serum samples per patient was available. sPLA2 was measured in patient and matched control samples and related to previous CRP, IgM RF, and anti-CCP measurements. The temporal relationship between the increased markers of inflammation and autoantibodies was analysed with time lag analysis. Results: IgM RF and anti-CCP concentrations were significantly associated (p<0.001) with concentrations of sPLA2, CRP, and the combination of sPLA2 and CRP at the same time point. However, we found no stronger association between the two autoantibody tests and the three inflammation measures 1, 2, and 3 years before or after a time point than for measurements at the same time, in the whole group or in subgroups of IgM RF and anti-CCP positive patients. Conclusion: Both the acute phase response and autoantibody formation often develop years before the first symptoms of RA occur, and these phenomena are probably closely connected in time.

Improvement of Lipid Profile Is Accompanied by Atheroprotective Alterations in High-Density Lipoprotein Composition Upon Tumor Necrosis Factor Blockade A Prospective Cohort Study in Ankylosing Spondylitis

OBJECTIVE Cardiovascular mortality is increased in ankylosing spondylitis (AS), and inflammation plays an important role. Inflammation deteriorates the lipid profile and alters high-density lipoprotein cholesterol (HDL-c) composition, reflected by increased concentrations of serum amyloid A (SAA) within the particle. Anti-tumor necrosis factor (anti-TNF) treatment may improve these parameters. We therefore undertook the present study to investigate the effects of etanercept on lipid profile and HDL composition in AS. METHODS In 92 AS patients, lipid levels and their association with the inflammation markers C-reactive protein (CRP), erythrocyte sedimentation rate, and SAA were evaluated serially during 3 months of etanercept treatment. HDL composition and its relationship to inflammation markers was determined in a subgroup of patients, using surface-enhanced laser desorption/ionization time-of-flight analysis. RESULTS With anti-TNF treatment, levels of all parameters of inflammation decreased significantly, whereas total cholesterol, HDL-c, and apolipoprotein A-I (Apo A-I) levels increased significantly. This resulted in a better total cholesterol:HDL-c ratio (from 3.9 to 3.7) (although the difference was not statistically significant), and an improved Apo B:Apo A-I ratio, which decreased by 7.5% over time (P=0.008). In general, increases in levels of all lipid parameters were associated with reductions in inflammatory activity. In addition, SAA was present at high levels within HDL particles from AS patients with increased CRP levels and disappeared during treatment, in parallel with declining plasma levels of SAA. CONCLUSION Our results show for the first time that during anti-TNF therapy for AS, along with favorable changes in the lipid profile, HDL composition is actually altered whereby SAA disappears from the HDL particle, increasing its atheroprotective ability. These findings demonstrate the importance of understanding the role of functional characteristics of HDL-c in cardiovascular diseases related to chronic inflammatory conditions.

Changes in lipid profile during infliximab and corticosteroid treatment in rheumatoid arthritis

Objective: To evaluate the effects of infliximab and corticosteroid treatment on the lipid profile in patients with active rheumatoid arthritis (RA). Methods: Infliximab infusions were given at weeks 0, 2, 6 and then every 8 weeks. Before each infusion, disease activity parameters (Disease Activity Index 28-Joint Score (DAS28)) C reactive protein (CRP) and lipid levels (total cholesterol, high-density lipoprotein (HDL)-cholesterol, triglycerides, apolipoprotein A1 (apo A1) and apolipoprotein B) were measured in 80 consecutive patients with RA, who completed the study period of 48 weeks. Longitudinal analyses were used to investigate (1) the course of lipid levels over a period of time and (2) the relationship between lipids, prednisone dose and disease activity. Results: Infliximab treatment causes a significant reduction in disease activity and a concomitant decrease in prednisone dose. Although they initially improved significantly, all lipid levels had returned to baseline levels after 48 weeks, except for apo A1. Longitudinal analyses revealed significant yet opposite associations between lipid levels and disease activity and between lipid levels and prednisone dose. DAS28 improvement by 1 point was associated with an increase of 0.016 mmol/l (0.618 mg/dl) total cholesterol and 0.045 mmol/l (1.737 mg/dl) HDL-cholesterol. Reduction of 10 mg prednisone was associated with a decrease of 0.04 mmol/l (1.544 mg/dl) total cholesterol and 0.16 mmol/l (6.177 mg/dl) HDL-cholesterol. Conclusion: Overall, no changes in serum lipid levels were observed after 48 weeks of infliximab treatment. The initial beneficial effects of infliximab on the lipid profile, by means of a reduction of disease activity, are attenuated by a concomitant decrease in prednisone dose.

Increased disease activity is associated with a deteriorated lipid profile in patients with ankylosing spondylitis.

Background: Cardiovascular mortality is increased in patients with ankylosing spondylitis. A possible explanation might be a more prevalent atherogenic lipid profile in patients with ankylosing spondylitis than in the general population. It has been postulated that inflammation deteriorates the lipid profile, thereby increasing cardiovascular risk. Objective: To explore the association between disease activity and lipid profile in patients with ankylosing spondylitis. Methods: Disease activity parameters for ankylosing spondylitis and lipid levels (total cholesterol, high-density lipoprotein cholesterol (HDLc) and triglycerides) were measured in 45 patients with ankylosing spondylitis for 6 months after starting treatment with leflunomide or placebo. Findings in this treatment group were compared with those in 10 patients with ankylosing spondylitis treated with etanercept. A specialised regression model, adjusting for repeated measurements, age and sex, was used to assess the influence of the disease activity variables on the lipid levels. Results: Multilevel regression analyses showed significant associations between disease activity parameters and lipid levels—for instance, an increase of 30 mm at the end of the first hour in erythrocyte sedimentation rate was associated with a decrease of about 6% in total cholesterol level and a decrease of about 11% in HDLc levels. Similar significant associations were found between other disease activity parameters and lipid levels. Conclusion: Increase in disease activity was associated with decreases in lipid levels. The decrease in HDLc levels tended to be almost twice as large as the decrease in total cholesterol levels, resulting in a more atherogenic lipid profile. Hence, effective treatment of disease activity in patients with ankylosing spondylitis may lower the cardiovascular risk by improving the lipid profile.

Effect of dexamethasone on autoantibody levels and arthritis development in patients with arthralgia: a randomised trial

Background Rheumatoid arthritis is characterised by antibodies to citrullinated proteins (ACPA) and rheumatoid factor (RF) in the preclinical phase. Objective To determine whether an intervention aimed at decreasing autoantibody levels in people at risk may be effective in preventing progression to arthritis. Methods 83 patients with arthralgia positive for ACPA or IgM-RF were randomly allocated to intramuscular injections of 100 mg dexamethasone or placebo at baseline and 6 weeks. The primary end point was a 50% antibody reduction or normalisation at 6 months. Results The primary end point was reached in one patient in each group. Patients treated with dexamethasone had reductions of antibody levels after 1 month (ACPA 222% and IgM-RF 214%), which persisted at 6 months for ACPA. During a median follow-up of 26 months, arthritis development in both groups was similar (20% vs 21%). Conclusion In autoantibody-positive patients with arthralgia, dexamethasone treatment decreases ACPA and IgM-RF levels, but does not prevent arthritis development. Trial registration number: ISRCTN73232918.

The equilibrium between the mitochondrial ATPase (F1) and its natural inhibitor in submitochondrial particles.

Abstract 1. The reversible equilibrium between the mitochondrial ATPase (F 1 ) and its naturally occurring inhibitor in Mg-ATP submitochondrial particles has been studied under different conditions. 2. High ionic strength favours dissociation of the ATPase inhibitor as tested by ATPase and ATP-driven transhydrogenase activities. 3. Dissociation of the ATPase inhibitor results in an increased maximal velocity of the ATPase activity measured in the presence of uncoupler and an increased affinity for adenine nucleotides, in particular for ATP. 4. Association of the ATPase inhibitor with inhibitor-depleted Mg-ATP particles causes a slowing of the initial rate of succinate oxidation. 5. The antibiotic aurovertin stimulates the ATPase activity of Mg-ATP particles preinculbated in the presence of a supply of oxidative energy. Bound aurovertin impedes the association of inhibitor-deficient particles with ATPase inhibitor. 6. The fluorescence of aurovertin bound to inhibitor-containing particles is much less than that of aurovertin bound to inhibitor-depleted particles. 7. The oligomycin-sensitivity-conferring protein, added either alone or in the presence or absence of membranous components of the ATPase complex, has little or no effect on the fluorescence of the F 1 -aurovertin complex. 8. It is suggested that the ATPase inhibitor brings F 1 in a conformation denoted ∗F 1 that binds aurovertin with a low quantum yield, a decreased affinity and an increased binding capacity.