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Abstract Purpose  Previous positron emission tomography (PET) studies have shown increased 2-deoxy-2-[18F]fluoro-d-glucose (FDG) uptake in joints of patients with osteoarthritis (OA) and inflamed joints of patients with rheumatoid arthritis (RA). This study compares FDG uptake in joints of RA and OA patients and FDG-uptake with clinical signs of inflammation. Procedures  FDG-PET scans of hands and wrists were performed in patients with RA and primary OA. PET data were compared with clinical data. Results  29% of RA joints and 6% of OA joints showed elevated FDG-uptake. The level of uptake in PET-positive OA joints was not significantly different from that in RA joints. The majority of PET results of RA joints corresponded with clinical findings. Clinical synovitis was found some OA joints with FDG-uptake. Conclusions  FDG-uptake was observed in the majority of clinically inflamed RA joints and in a few OA joints with no significant difference in uptake level. The latter may be due to secondary synovitis. [ABSTRACT FROM AUTHOR]

Background: The efficacy and safety of bimekizumab (BKZ), an inhibitor of interleukin (IL)-17F in addition to IL-17A, has been established in axial spondyloarthritis (axSpA). Early assessment of new bone formation is possible using 18 F-fluoride positron emission tomography-computerised tomography (PET-CT) imaging to quantitatively monitor osteoblastic activity., Objectives: This exploratory study, initiated before phase IIb/III studies, assessed the efficacy and safety of BKZ in patients with radiographic (r-)axSpA and its effect on new bone formation., Design: Patients were randomised 2:1 to BKZ 160 mg every 2 weeks (Q2W; Weeks 0-10) then 320 mg Q4W (Weeks 12-44), or the reference drug: certolizumab pegol (CZP) 400 mg Q2W (Weeks 0-4), then 200 mg Q2W (Weeks 6-10), 400 mg Q4W (Weeks 12-44)., Methods: Primary (Axial Spondyloarthritis Disease Activity Score (ASDAS) change from baseline (CfB)) and secondary endpoints (ASDAS-ID, ASDAS-MI) were assessed at Week 12. PET-positive axSpA lesion counts and osteoblastic activity quantification (mean SUV auc ) were performed at baseline and Weeks 12 and 48 in the sacroiliac joints and spine (PET-CT substudy; not powered to evaluate differences)., Results: In total, 76 patients were randomised; 26/76 entered the PET-CT substudy. At Week 12, the mean ASDAS CfB with BKZ was -2.1 (CZP: -1.8); ASDAS-ID and ASDAS-MI were achieved by 23.9% (11/46) (CZP: 20.8% (5/24)) and 60.9% (28/46) (CZP: 45.8% (11/24)) patients. Across treatments, clinical efficacy was maintained or increased further at Week 48. In the PET-CT substudy, the total number of PET-positive axSpA lesions and mean SUV auc were substantially reduced from baseline at Week 12 with BKZ and CZP, with reductions maintained or further reduced at Week 48. Treatments were well tolerated with no new safety signals., Conclusion: Dual inhibition of IL-17A and IL-17F with BKZ resulted in improved clinical outcomes and reduced osteoblastic activity in patients with r-axSpA, suggesting the potential of BKZ to reduce disease activity and new bone formation within 12 weeks of treatment. CZP findings were consistent with previous data. No new safety signals were identified., Trial Registration: ClinicalTrials.gov, NCT03215277 (https://clinicaltrials.gov/study/NCT03215277)., Competing Interests: X.B.: Speakers bureau from AbbVie, BMS, Chugai, Eli Lilly, Galapagos, MSD, Novartis, Pfizer, UCB; paid instructor for AbbVie, BMS, Chugai, Eli Lilly, Galapagos, MSD, Novartis, Pfizer, UCB; consultant of AbbVie, BMS, Chugai, Eli Lilly, Galapagos, Gilead, Novartis, Pfizer, UCB; grant/research support from: Novartis, UCB; J.d.J.: Employee of Teva Pharmaceuticals since May 2023; D.P.: Speaker for AbbVie, BMS, Eli Lilly, MSD, Novartis, Pfizer and UCB; consultant for AbbVie, Biocad, Eli Lilly, Gilead, GSK, MSD, MoonLake, Novartis, Pfizer, Samsung Bioepis and UCB; grant/research support from: AbbVie, Lilly, MSD, Novartis and Pfizer; G.J.C.Z.: No potential conflicts of interest declared; R.H.: No potential conflicts of interest declared; S.G., S.S., L.I., J.M., R.P.M., T.V. and N.d.P.: Employees of UCB; A.e.B. and D.B.: Former employees of UCB; M.O.: Employee and stockholder of UCB; C.v.d.L.: Consultant or advisor for Lilly, Galapagos, GSK, UCB; research support from AbbVie, GSK, Novartis, Pfizer, UCB., (© The Author(s), 2024.)

Macrophages constitute important immune cell targets of the antifolate methotrexate (MTX) in autoimmune diseases, including rheumatoid arthritis. Regulation of folate/MTX metabolism remains poorly understood upon pro-inflammatory (M1-type/GM-CSF-polarized) and anti-inflammatory (M2-type/M-CSF-polarized) macrophages. MTX activity strictly relies on the folylpolyglutamate synthetase (FPGS) dependent intracellular conversion and hence retention to MTX-polyglutamate (MTX-PG) forms. Here, we determined FPGS pre-mRNA splicing, FPGS enzyme activity and MTX-polyglutamylation in human monocyte-derived M1- and M2-macrophages exposed to 50 nmol/L MTX ex vivo. Moreover, RNA-sequencing analysis was used to investigate global splicing profiles and differential gene expression in monocytic and MTX-exposed macrophages. Monocytes displayed six-eight-fold higher ratios of alternatively-spliced/wild type FPGS transcripts than M1- and M2-macrophages. These ratios were inversely associated with a six-ten-fold increase in FPGS activity in M1- and M2-macrophages versus monocytes. Total MTX-PG accumulation was four-fold higher in M1- versus M2-macrophages. Differential splicing after MTX-exposure was particularly apparent in M2-macrophages for histone methylation/modification genes. MTX predominantly induced differential gene expression in M1-macrophages, involving folate metabolic pathway genes, signaling pathways, chemokines/cytokines and energy metabolism. Collectively, macrophage polarization-related differences in folate/MTX metabolism and downstream pathways at the level of pre-mRNA splicing and gene expression may account for variable accumulation of MTX-PGs, hence possibly impacting MTX treatment efficacy.

Objective: To determine whether macrophage positron emission tomography (PET)/computed tomography (CT) imaging using ( R )-[ 11 C]PK11195 at 0 and 2 weeks is associated with clinical response at 13 weeks in patients with early rheumatoid arthritis (RA)., Methods: Whole-body ( R )-[ 11 C]PK11195 PET/CT scans were performed at baseline and after 2 weeks of COBRA-light (combination therapy of methotrexate and prednisone) treatment in 35 patients with clinically active early RA. Clinical assessment (Disease Activity Score of 44 joints (DAS44)) was performed at 0, 2 and 13 weeks of treatment. PET/CT scans were assessed visually by two blinded, experienced readers, and by calculating standardised uptake values (SUVs) for shoulders, elbows, hips, knees, and hand and feet joints. Clinical and PET variables were compared using (multivariate) linear regression., Results: 18 males and 17 females were included (baseline DAS44=3.2 ± 1.0). 171 out of 1470 joints were visually PET positive at baseline, decreasing to 100 joints after 2 weeks. In general, small feet joints showed the highest uptake at baseline, and the largest decrease after 2 weeks (Δ 0-2 ). Neither baseline nor Δ 0-2 PET measures correlated with DAS44 at 13 weeks. However, at 2 weeks, average SUV of the feet significantly correlated with DAS44 at 13 weeks (R 2 =0.14, p=0.04). In a multivariable model, DAS44 and average SUV of the feet at 2 weeks showed substantial combined predictive value (combined R 2 =0.297, p<0.01)., Conclusion: Quantitative macrophage PET assessment of feet joints, together with DAS44, after 2 weeks of COBRA light treatment in patients with early RA correlates with clinical response after 3 months of treatment., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Objective: RA is associated with higher risk of cardiovascular (CV) disease. Ongoing systemic inflammation is presumed to accelerate atherosclerosis by increasing inflammation in the arterial wall. However, evidence supporting this hypothesis is limited. We aimed to investigate arterial wall inflammation in RA vs OA, and its association with markers of inflammation and CV risk factors., Methods: 18-fluorodeoxyglucose PET combined with CT (18F-FDG-PET/CT) was performed in RA (n = 61) and OA (n = 28) to investigate inflammatory activity in the wall of large arteries. Secondary analyses were performed in patients with early untreated RA (n = 30), and established RA, active under DMARD treatment (n = 31) vs OA., Results: Patients with RA had significantly higher 18F-FDG uptake in the wall of the carotid arteries (beta 0.27, 95%CI 0.11-0.44, P <0.01) and the aorta (beta 0.47, 95%CI 0.17-0.76, P <0.01) when compared with OA, which persisted after adjustment for traditional CV risk factors. Patients with early RA had the highest 18F-FDG uptake, followed by patients with established RA and OA respectively. Higher ESR and DAS of 28 joints values were associated with higher 18F-FDG uptake in all arterial segments., Conclusion: Patients with RA have increased 18F-FDG uptake in the arterial wall compared with patients with OA, as a possible marker of early atherosclerosis. Furthermore, a higher level of clinical disease activity and circulating inflammatory markers was associated with higher arterial 18F-FDG uptake, which may support a role of arterial wall inflammation in the pathogenesis of vascular complications in patients with RA., (© The Author(s) 2021. Published by Oxford University Press on behalf of the British Society for Rheumatology.)

Objective: To investigate the efficacy of 16-week treatment with etanercept (ETN) in patients with suspected nonradiographic axial spondyloarthritis (SpA)., Methods: Tumor necrosis factor inhibitor-naive patients with inflammatory back pain with at least 2 SpA features and high disease activity (Bath Ankylosing Spondylitis Disease Activity Index score ≥4), without the requirement of a positive finding on magnetic resonance imaging (MRI) of the sacroiliac (SI) joint and/or elevated C-reactive protein (CRP) level, were randomized (1:1) to receive ETN (n = 40) or placebo (n = 40) for 16 weeks and subsequently were followed up for a further 8 weeks (to 24 weeks from baseline) without study medication. The primary end point was the Assessment of SpondyloArthritis international Society 20 (ASAS20) response at 16 weeks. Secondary end points included the Ankylosing Spondylitis Disease Activity Score (ASDAS) and changes in disease parameters, including the Bath Ankylosing Spondylitis Metrology Index (BASMI), CRP level, erythrocyte sedimentation rate (ESR), and Spondyloarthritis Research Consortium of Canada index scores (MRI of the SI joint), after 16 and 24 weeks., Results: Patient characteristics at baseline were comparable between the ETN and placebo groups. At 16 weeks, there was no significant difference in the percentage of patients exhibiting ASAS20 response between the ETN group (6 patients [16.7%]) and the placebo group (4 patients [11.1%]) (relative risk 0.7 [95% confidence interval 0.2-2.2], P = 0.5). Only the ESR showed more improvement in the ETN group compared to the placebo group at 16 weeks (decreases of 2.2 mm/hour and 1.4 mm/hour, respectively), but the difference did not reach statistical significance. Between 16 and 24 weeks, without study medication, the BASMI, CRP level, and ESR had worsened to a greater extent in the ETN group compared to the placebo group, with the difference being significant for the CRP level., Conclusion: This study shows that in patients with suspected nonradiographic axial SpA with high disease activity but without the requirement of a positive finding on SI joint MRI and/or elevated CRP level, treatment with ETN is not effective., (© 2020 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology.)

Background: Folylpolyglutamate synthetase (FPGS) is a crucial enzyme in both cellular folate homeostasis and the intracellular retention of folate analogue drugs such as methotrexate (MTX), which is commonly used for the treatment of (pediatric) leukemia and the anchor drug in rheumatoid arthritis (RA) treatment. To date, assessment of FPGS catalytic activity relies on assays using radioactive substrates that are labor-intensive and require relatively large numbers of cells. Here, we describe a nonradioactive, ultra-high-performance liquid chromatography-tandem mass spectrometer (UHPLC-MS/MS)-based method allowing for sensitive and accurate measurements of FPGS activity in low cell numbers (ie, 1-2 × 10) of biological specimens, including leukemic blast cells of acute lymphoblastic leukemia patients and peripheral blood mononuclear cells of patients with RA., Methods: The UHPLC-MS/MS assay was validated with 2 CCRF-CEM human leukemia cells, one proficient and one deficient in FPGS activity. Linearity of time and protein input were tested by measuring FPGS activity at 30-180 minutes of incubation time and 10-300 mcg protein extract. In addition, FPGS enzyme kinetic parameters were assessed., Results: The FPGS enzymatic assay showed a linear relation between FPGS activity and protein input (R ≥ 0.989) as well as incubation time (R ≥ 0.996). Moreover, the UHPLC-MS/MS method also allowed for evaluation of FPGS enzyme kinetic parameters revealing Km values for the substrates MTX and L-glutamic acid of 64 µmol/L and 2.2 mmol/L, respectively. The mean FPGS activity of acute lymphoblastic leukemia blast cells (n = 4) was 3-fold higher than that of CCRF-CEM cells and 44-fold and 88-fold higher than that of peripheral blood mononuclear cells from MTX-naive (n = 9) and MTX-treated RA patients (n = 6), respectively., Conclusions: Collectively, given its sensitivity with low cell numbers and avoidance of radioactive substrates, UHPLC-MS/MS-based analysis of FPGS activity may be eligible for routine therapeutic drug monitoring of MTX in RA and leukemia for therapy (non)response evaluations.

Background: B cells are key players in the pathogenesis of rheumatoid arthritis (RA). Although successful in 50-60% of patients with RA, anti-B-cell therapy given as rituximab could be more efficient by identifying potential responders prior to treatment. Positron emission tomography (PET) using radiolabeled rituximab for B-cell imaging might provide the means to fulfil this unmet clinical need. The objective of this study was to investigate the association between biodistribution of zirconium-89 ( 89 Zr)-rituximab on PET-computed tomography (CT) and clinical response in patients with RA., Methods: We included 20 patients with RA who were starting rituximab treatment. At the first intravenous (i.v.) therapeutic dose, patients were also injected with 89 Zr-rituximab, followed by PET-CT. European League Against Rheumatism (EULAR) response criteria were applied to determine response at week 24. PET-CT was analyzed visually and quantitatively. Lymph node (LN) biopsies were performed at 0 and 4 weeks to correlate B-cell counts with imaging data., Results: PET-positive hand joints (range 1-20) were observed in 18/20 patients. Responders had significantly higher 89 Zr-rituximab uptake in PET-positive hand joints than non-responders (median target-to-background (T/B)) ratios (IQR) were 6.2 (4.0-8.8) vs. 3.1 (2.2-3.9), p = 0.02). At T/B ≥4.0, positive and negative predictive values for clinical response were respectively 90% and 75%. Quantitative 89 Zr-rituximab hand joint uptake on PET correlated inversely with CD22 + B-cell count in LN tissue at 4 weeks of treatment (r = 0.6, p = 0.05). In addition, the CD22 + B-cell count in LN correlated positively with quantitative LN PET data at baseline, supporting the specificity of B-cell imaging on PET., Conclusions: Non-invasive B-cell imaging by 89 Zr-rituximab PET-CT has promising clinical value to select RA responders to rituximab at baseline. 89 Zr-rituximab PET-CT may also hold promise for monitoring anti-B-cell therapies in other B-cell driven autoimmune diseases, such as systemic lupus erythematosus and Sjögren's disease.

The diagnosis of inflammatory processes is an important goal in medicine. In some cases the diagnosis is easy, based on the clinical history and the physical examination of the patient. Other cases are more difficult to diagnose because they are asymptomatic or with non-specific symptoms. Thus, several imaging techniques have been developed for the diagnosis of inflammatory processes, from the simple X-ray to the more sophisticated computerised tomography, magnetic resonance imaging and nuclear medicine scan. They provide different information and their role in different diseases will be discussed in this review with particular emphasis on the expanding field of the use of radiolabelled cytokines for imaging infection/inflammation. So far, IL-1, IL-1ra, IL-2, IL-6, IL-8, IL-10, IL-12 p40, G-CSF, IFN-gamma and EGF have been radiolabelled for in vivo targetting of different leukocyte subsets with promising results for their clinical use., (Copyright 2000 Academic Press.)