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Objective: Infliximab-treated patients with rheumatoid arthritis (RA) may respond insufficiently due to low serum infliximab (sIFX) levels, caused by anti-drug antibodies (ADAs). However, monitoring of sIFX and ADAs is not routinely implemented, and levels for optimal outcome have not been validated. We searched for predictors for sIFX < 0.2 μg/mL and ADA development in a randomized setting. Methods: In the SWEFOT trial, of 128 patients randomized to methotrexate + IFX therapy, 101 had serum samples at 3, 9, and 21 months that were analysed for sIFX [enzyme-linked immunosorbent assay (ELISA)] and ADAs [ELISA, and precipitation and acid dissociation (PandA) when sIFX > 0.2 μg/mL]. The primary and secondary outcome measures were low disease activity [LDA = 28-joint Disease Activity Score (DAS28) ≤ 3.2] and remission (DAS28 < 2.6). Baseline characteristics were assessed as potential predictors of sIFX < 0.2 μg/mL or ADA positivity, using logistic regression. Results: Categorization of sIFX levels into < 0.2, 0.2-2.9, 3.0-7.0, and > 7.0 μg/mL showed a dose-response association with LDA (30%, 64%, 67%, and 79%, respectively, p = 0.008) and remission (10%, 45%, 39%, and 66%, p = 0.004) at trial cessation (21 months). Female patients had sIFX < 0.2 μg/mL more often than males (35% vs 7%, p = 0.006), with a similar trend for rheumatoid factor (RF)-positive vs RF-negative patients (34% vs 16%, p = 0.059). ADA positivity showed similar patterns, also after adjustment for potential confounders (female sex: p = 0.050; RF positivity: p = 0.067). PandA captured four highly ADA-reactive patients with sIFX > 0.2 μg/mL, of whom three were ADA positive at other time-points, all with high DAS28 at follow-up. Conclusion: In early RA patients receiving IFX as a second-line agent, sIFX < 0.2 μg/mL and ADA development were associated with treatment failure and were more common in females, with a similar trend for RF positivity. Our findings support the use of therapeutic drug monitoring, and PandA in ADA-negative non-responders. Trial registration: SWEFOT NCT00764725 ( https://clinicaltrials.gov/ct2/show/NCT00764725 ). [ABSTRACT FROM AUTHOR]

Thang PH, Ruffin N, Brodin D, Rethi B, Cam PD, Hien NT, Lopalco L, Vivar N, Chiodi F (Karolinska Institutet, Stockholm, Sweden; National Institute of Hygiene and Epidemiology, Hanoi, Vietnam; San Raffaele Scientific Institute, Milan, Italy). The role of IL-1β in reduced IL-7 production by stromal and epithelial cells: a model for impaired T-cell numbers in the gut during HIV-1 infection. J Intern Med 2010; 268: 181–193. Objectives. Interleukin (IL)-7 is a key cytokine in T-cell homeostasis. Stromal cells, intestinal epithelial cells and keratinocytes are known to produce this cytokine. The mechanisms and cellular factors regulating IL-7 production are still unclear. We assessed whether IL-1β and interferon (IFN)-γ, cytokines produced during inflammatory conditions, may impact on IL-7 production. Design. We used human intestinal epithelial cells (DLD-1 cell line) and bone marrow stromal cells (HS27 cell line), known to produce IL-7; IL-7 production was evaluated at the mRNA and protein levels. To assess whether treatment of HS27 cells with IL-1β and/or IFN-γ leads to changes in the gene expression of cytokines, Toll-like receptors (TLRs) and chemokines, we analysed gene expression profiles using the whole-genome microarray Human Gene 1.0 ST. Results. We found that IFN-γ enhanced the expression of IL-7 mRNA ( P < 0.001) in both cell lines. IL-1β treatment led to a significant down-regulation ( P < 0.001) of IL-7 mRNA expression in both cell lines. The IL-7 concentration in supernatants collected from treated DLD-1 and HS27 cell cultures reflected the trend of IL-7 mRNA levels. The gene profiles revealed dramatic changes in expression of cytokines and their receptors (IL-7/IL-7Rα; IL-1α,IL-1β/IL-1R1; IFN-γ/IFN-γR1), of IFN regulatory factors (IRF-1 and 2), of TLRs and of important chemo-attractants for T cells. The microarray results were verified by additional methods. Conclusions. Our results are discussed in the setting of inflammation and T-cell survival in the gut compartment during HIV-1 infection where stromal and epithelial cells may produce factors that contribute to impaired IL-7 homeostasis and homing of T cells. [ABSTRACT FROM AUTHOR]