Background: A substantial proportion of patients with rheumatoid arthritis (RA) do not respond, or lose initial response, to adalimumab treatment. One explanation for non-response is that patients develop antiadalimumab antibodies. Objectives: To evaluate the incidence of formation of antibody against adalimumab and the association with serum adalimumab concentrations and clinical response. Methods: In a cohort of 121 consecutive patients with RA treated with adalimumab, serum adalimumab concentrations and antibodies against adalimumab were measured together with clinical response variables before and up to 28 weeks after the start of treatment. Results: Anti-adalimumab antibodies were detected in 21 patients (17%) during 28 weeks of treatment. EULAR non-responders had antibodies significantly more often than good responders (34% vs 5%; p = 0.032). Patients with antibodies showed less improvement in disease activity (mean (SD) delta DAS28 0.65 (1.35)) than patients without antibodies (mean delta DAS28 1.70 (1.35)) (p = 0.001). Patients with antibodies during follow-up had lower serum adalimumab concentrations at 28 weeks than patients without antibodies (median 1.2 mg/l, range 0.0-5.6 vs median 11.0 mg/l, range 2.0-33.0, respectively; p,0.001). Good responders had higher serum adalimumab concentrations than moderate responders (p = 0.021) and non-responders (p = 0.001). Concomitant methotrexate use was lower in the group with antiadalimumab antibodies (52%) than in the group without antibodies (84%) (p = 0.003). Conclusions: Serum antibodies against adalimumab are associated with lower serum adalimumab concentrations and non-response to adalimumab treatment.

Objective:To investigate the synovial tissue in patients with rheumatoid arthritis (RA) treated with rituximab and to identify possible predictors of clinical response.Methods:A total of 24 patients with RA underwent synovial biopsy before, 4 and 16 weeks after initiation of rituximab treatment (without peri-infusional corticosteroids to prevent bias). Immunohistochemical analysis was performed and stained sections were analysed by digital image analysis. Linear regression analysis was used to identify predictors of clinical response.Results:The 28-joint Disease Activity Score (DAS28) was unaltered at 4 weeks, but significantly reduced at 16 and 24 weeks. Serum levels of IgM-rheumatoid factor (RF) decreased significantly at 24 weeks and anti-citrullinated peptide antibody (ACPA) levels at 36 weeks. Peripheral blood B cells were depleted at 4 weeks and started to return at 24 weeks. Synovial B cells were significantly decreased at 4 weeks, but were not completely depleted in all patients; there was a further reduction at 16 weeks in some patients. We found a significant decrease in macrophages at 4 weeks, which was more pronounced at 16 weeks. At that timepoint, T cells were also significantly decreased. The reduction of plasma cells predicted clinical improvement at 24 weeks.Conclusions:The results support the view that B cells orchestrate local cellular infiltration. The kinetics of the serological as well as the tissue response in clinical responders are consistent with the notion that rituximab exerts its effects in part by an indirect effect on plasma cells associated with autoantibody production, which could help explain the delayed response after rituximab treatment.Trial registration number: ISRCTN05568900.

The IFN type I signature defines a subgroup of patients with RA, with a distinct biomolecular phenotype, characterised by increased activity of the innate defence system, coagulation and complement cascades, and fatty acid metabolism.

Switchers with anti-infliximab antibodies more often develop antibodies against adalimumab than anti-TNF naive patients. Response to adalimumab was limited in switchers without anti-infliximab antibodies, which raises the question whether a second anti-TNF treatment should be offered to patients with RA for whom an initial treatment with an anti-TNF blocker fails, in the absence of anti-biological antibodies.

Objective. To study the specific effects of rituximab treatment on the synovium in patients with rheumatoid arthritis (RA) early after initiation of treatment.Methods. Seventeen RA patients underwent an arthroscopic synovial biopsy procedure directly before and 1 month after receiving 2 infusions of the chimeric anti-CD20 monoclonal antibody rituximab (1,000 mg on days 1 and 15; both without methylprednisolone premedication). Immunohistochemical analysis was performed to characterize the cell infiltrate. Stained tissue sections were analyzed by digital image analysis. Statistical analysis was performed using Wilcoxon's signed rank test. Conclusion. Rituximab treatment leads to a rapid and significant decrease in synovial B cell numbers, but not in all patients. Whether the variable tissue response is related to the clinical response over time remains to be clarified. Results. No significant change in the Disease

Objective. Adipose tissue has immunomodulating effects in rheumatoid arthritis (RA), although the exact role is, at present, unclear. The purpose of this study was to determine whether body mass index (BMI) affects response to infliximab in RA patients investigated prospectively.Methods. In 89 patients with active RA, the BMI was calculated before initiation of infliximab treatment (3 mg/kg intravenously). After 16 weeks of treatment, changes in disease activity were assessed with the Disease Activity Score in 28 joints (DAS28).Results. The mean ؎ SD BMI was 26 ؎ 5 kg/m 2 (range 17-42). The BMI correlated positively with the DAS28 at baseline (r ‫؍‬ 0.34, P ‫؍‬ 0.001). Since selection of study patients according to DAS28 values could influence the clinical response to tumor necrosis factor (TNF) blockade due to regression to the mean because the clinical response is itself based on the change in the DAS28 values, analysis of covariance was used to correct for the baseline DAS28. A highly significant, negative association between the BMI and the absolute decrease in the DAS28 after 16 weeks (P ‫؍‬ 0.001) was found also when adjusted for anti-citrullinated protein antibodies. Conclusion.Although the infliximab dosage is based on body weight, RA patients with a high BMI responded less well to infliximab, a finding that held true when adjusted for the baseline DAS28 or anticitrullinated protein antibody status. These results support the notion that adipose tissue may be involved in the pathophysiology of RA and could have implications for other immune-mediated inflammatory conditions treated with TNF antagonists.

Objective. To investigate the relationship between lymphoid neogenesis in the synovium of patients with rheumatoid arthritis (RA) and characteristics of inflammation and disease severity.Methods. Arthroscopic synovial biopsy was performed in 103 patients with active RA (Disease Activity Score 28-joint assessment >3.2) who had not received treatment with biologic agents. Sections were stained and assessed by digital image analysis. Lymphocyte aggregates were counted and graded for size (1-3). Synovial lymphoid neogenesis was defined as the presence of grade 2 or 3 aggregates and subclassified based on the presence of follicular dendritic cells (FDCs).Results. Lymphoid neogenesis was present in 31% of the RA synovial tissues, whereas an additional 25% contained only grade 1 aggregates. FDCs were present in 28% of the samples with lymphoid neogenesis, corresponding to 8% of the total RA cohort. Histologically, synovia with lymphoid neogenesis showed increased infiltration by T and B lymphocytes, plasma cells, and macrophages, and increased expression of tumor necrosis factor ␣ and lymphotoxin ␤ compared with samples without lymphoid neogenesis. Patients with lymphoid neogenesis also had higher C-reactive protein levels, erythrocyte sedimentation rates, and leukocyte and thrombocyte counts, but exhibited no increase in the severity of clinical signs and symptoms. Of importance, there was no relationship between the presence of lymphoid neogenesis and IgM rheumatoid factor or anti-citrullinated protein antibodies. The presence of lymphocyte aggregates with FDCs did not define a specific clinical phenotype compared with lymphocyte aggregates without FDCs.Conclusion. These findings indicate that synovial lymphoid neogenesis is associated with more severe synovial and systemic inflammation, but this is not confined to a specific clinical subset of RA.

Objective:To determine whether the heterogeneous clinical response to tumour necrosis factor (TNF)α blocking therapy in rheumatoid arthritis (RA) can be predicted by TNFα expression in the synovium before initiation of treatment.Methods:Prior to initiation of infliximab treatment, arthroscopic synovial tissue biopsies were obtained from 143 patients with active RA. At week 16, clinical response was evaluated using the 28-joint Disease Activity Score (DAS28). Immunohistochemistry was used to analyse the cell infiltrate as well as the expression of various cytokines, adhesion molecules and growth factors. Stained sections were evaluated by digital image analysis. Student t tests were used to compare responders (decrease in DAS28 ⩾1.2) with non-responders (decrease in DAS28 <1.2) and multivariable regression was used to identify the independent predictors of clinical response.Results:Synovial tissue analysis confirmed our hypothesis that the baseline level of TNFα expression is a significant predictor of response to TNFα blocking therapy. TNFα expression in the intimal lining layer and synovial sublining were significantly higher in responders than in non-responders (p = 0.047 and p = 0.008, respectively). The numbers of macrophages, macrophage subsets and T cells (all able to produce TNFα) were also significantly higher in responders than in non-responders. The expression of interleukin (IL)1β, IL6, IL18, IL10, E-selectin, intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1, vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) was not associated with response to anti-TNFα treatment.Conclusion:The effects of TNFα blockade are in part dependent on synovial TNFα expression and infiltration by TNFα producing inflammatory cells. Clinical response cannot be predicted completely, indicating involvement of other as yet unknown mechanisms.