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T cell receptor (TCR) signal strength is a key determinant of T cell responses. We developed a cancer mouse model in which tumor-specific CD8 T cells (TST cells) encounter tumor antigens with varying TCR signal strength. High-signal-strength interactions caused TST cells to up-regulate inhibitory receptors (IRs), lose effector function, and establish a dysfunction-associated molecular program. TST cells undergoing low-signal-strength interactions also up-regulated IRs, including PD1, but retained a cell-intrinsic functional state. Surprisingly, neither high- nor low-signal-strength interactions led to tumor control in vivo, revealing two distinct mechanisms by which PD1hi TST cells permit tumor escape; high signal strength drives dysfunction, while low signal strength results in functional inertness, where the signal strength is too low to mediate effective cancer cell killing by functional TST cells. CRISPR-Cas9–mediated fine-tuning of signal strength to an intermediate range improved anti-tumor activity in vivo. Our study defines the role of TCR signal strength in TST cell function, with important implications for T cell–based cancer immunotherapies.

A large-scale mathematical model, the Entelos Rheumatoid Arthritis (RA) PhysioLab platform, has been developed to describe the inflammatory and erosive processes in afflicted joints of people suffering from RA. The platform represents the life cycle of inflammatory cells, endothelium, synovial fibroblasts, and chondrocytes, as well as their products and interactions. The interplay between these processes culminates in clinically relevant measures for inflammation and erosion. The simulation model is deterministic, which allows tracing back the mechanism of action for a particular simulation result. Different patient phenotypes are represented by different virtual patients. The RA PhysioLab platform has been used to systematically and quantitatively study the predicted therapeutic effect of modulating several molecular targets, which resulted in a ranking of putative drug targets and a workflow to confirm the simulations experimentally. In addition, critical pathways were identified that drive the predicted disease outcome. Within these pathways, targets were identified from public literature that were not previously associated with arthritis. The model provides insights into the biology of RA and can be used as a platform for hypothesis-driven research. Case studies of therapies directed against IL-12 and IL-15 illustrate the approach, with emphasis on the analysis of system dynamics.

IntroductionReceptor activator of nuclear factor kappa B ligand (RANKL) is a key regulator of bone metabolism. Anti-citrullinated protein antibodies (ACPA) have been suggested to cause bone destruction by osteoclast activation. We investigated the relationship between RANKL and ACPA in patients with early untreated rheumatoid arthritis (RA).MethodsPatients with newly diagnosed untreated RA (n = 183) were analyzed at baseline and 3 months after initiating methotrexate (MTX) treatment. Serum RANKL (total RANKL), ACPA (anti-CCP2) and ACPA specificities (anti-citrullinated (cit)-vimentin, anti-cit-enolase and anti-cit-fibrinogen) were determined by enzyme-linked immunosorbent assay (ELISA). Synovial RANKL expression was evaluated by immunohistochemistry in a small group of patients (n = 15). The relationship between anti-cit-vim antibodies and bone destruction was further validated in 1116 RA patients included in the EIRA cohort. Pearson’s chi-square test, Wilcoxon rank sum test, Wilcoxon signed rank test and linear regression models were used.ResultsSerum RANKL concentration was significantly higher (p <0.05) in ACPA-positive (median: 689 pmol/L, IQR 342–1253) compared with ACPA-negative (median: 159 pmol/L, IQR 96–243) patients and this difference was also seen for synovial RANKL expression. Serum RANKL associated with ACPA (p <0.05) and bone erosions in rheumatoid factor (RF)-negative patients (n = 59). Among ACPA specificites, anti-cit-vimentin (amino acids 60–75) was associated with higher RANKL concentration and higher prevalence of bone erosion (p <0.05). Significant reductions in both serum RANKL and ACPA levels were observed after 3 months of MTX treatment (p <0.05).ConclusionsRANKL was elevated in ACPA-positive and in anti-cit-vimentin-positive patients with early untreated RA and associated with bone erosions. These findings give further support for an early direct pathogenic link between ACPA and bone destruction in RA.

A B lymphocyte that produces the immunoglobulin heavy (H) chain mu may switch to the production of another heavy chain class: gamma, epsilon, or alpha. Since the new heavy chain retains the original variable (V) region, antigenic specificity is maintained. The switch is accompanied by a large deletion of DNA at the heavy chain locus. To explain how this deletion is generated, three models have been proposed: recombination between homologs, unequal sister chromatid exchange, and looping out and deletion. While none of the predicted recombination products of the first two models have been found, both by-products of looping out--inversions and circular DNA--have been isolated. Thus looping out and deletion appears to be the appropriate model to explain the genetic events leading to the immunoglobulin heavy chain class switch. One requirement for switching may be transcription of the constant (C) region to which the cell switches. The switch rearrangement is catalyzed by a switch recombinase, and the isolation of the components of this putative enzyme system is in progress. Although the switch deletion is an accepted fact, the discussion is enlivened by scenarios for switching without DNA rearrangement; such suggestions include processing at the RNA level and trans-splicing.

Early changes in MBDA score were associated with clinical remission based on DAS28-CRP at 6 months. In anti-CCP-positive patients, a non-high baseline MBDA score (≤ 44) had a clinical value by predicting very low risk of radiographic progression at 12 months.

CYP1 determines the expression of several genes whose transcription is heme-dependent in yeast. It exerts regulatory functions even in the absence of heme, usually considered to be its effector. It mediates both positive and negative effects, depending on the target gene and on the redox state of the cell. In the presence of heme, it binds through a cysteine-rich domain in which a histidine residue occupies the position of the sixth and essential cysteine of the otherwise classical zinc cluster DNA-binding domain exemplified by GAL4. We constructed specific missense mutations in the potential CYP1 zinc cluster domain by site-directed mutagenesis and looked for regulatory effects of the mutated proteins under specific physiological conditions. We show that CYP1 does belong to the zinc cluster regulatory family since a sixth essential cysteine residue is indeed present, albeit at a modified position when compared to the consensus sequence. We also show that the amino acid preceding the first cysteine residue of the DNA-binding domain critically affects the efficiency of regulation both in the presence and in the absence of heme: mutations known to affect DNA binding under heme-sufficient conditions also affect regulation under heme-deficient conditions. We therefore surmise that regulation under heme-deficient conditions is dependent upon DNA binding.

Objectives. To assess the ability of a multi-biomarker disease activity (MBDA) score to track clinical response in patients with rheumatoid arthritis (RA) treated with diff erent TNF inhibitors. Methods. The study included 147 patients who had received adalimumab, etanercept, or infl iximab for a year or more, during routine clinical care at the University Hospital of Occupational and Environmental Health, Japan. MBDA scores and clinical measures of disease activity were evaluated at baseline and, after 24 weeks ( N ϭ 84) and 52 weeks of treatment. Relationships between the changes ( ∆ ) in MBDA score and changes in clinical measures or EULAR response categories were evaluated. Results. The median disease activity was 5.7 by DAS28-ESR and 64 by MBDA score at baseline, and decreased signifi cantly with treatment. ∆ MBDA scores over 1 year correlated with ∆ DAS28-ESR ( r ϭ 0.48) and ∆ DAS28-CRP ( r ϭ 0.46). Linear relationships between ∆ MBDA scores and ∆ DAS28-ESR or ∆ DAS28-CRP were not signifi cantly diff erent between TNF inhibitors. The MBDA scores declined signifi cantly more in good responders (median change: Ϫ 29) than moderate ( -21), and more in moderate than in non-responders ( ϩ 2), by the EULAR criteria. Conclusions . MBDA scores tracked disease activity and treatment response in patients with RA treated with three TNF inhibitors. The relationships between ∆ MBDA scores and ∆ DAS28-ESR or ∆ DAS28-CRP were consistent across the three TNF inhibitor groups.