Biological Switch Research Articles

Synthetic interleukin 22 (IL-22) signaling reveals biological activity of homodimeric IL-10 receptor 2 and functional cross-talk with the IL-6 receptor gp130

Cytokine signaling is transmitted by cell-surface receptors that function as biological switches controlling mainly immune-related processes. Recently, we have designed synthetic cytokine receptors (SyCyRs) consisting of GFP and mCherry nanobodies fused to transmembrane and intracellular domains of cytokine receptors that phenocopy cytokine signaling induced by nonphysiological homo- and heterodimeric GFP-mCherry ligands. Interleukin 22 (IL-22) signals via both IL-22 receptor α1 (IL-22Rα1) and the common IL-10R2, belongs to the IL-10 cytokine family, and is critically involved in tissue regeneration. Here, IL-22 SyCyRs phenocopied native IL-22 signal transduction, indicated by induction of cytokine-dependent cellular proliferation, signal transduction, and transcriptome analysis. Whereas homodimeric IL-22Rα1 SyCyRs failed to activate signaling, homodimerization of the second IL-22 signaling chain, SyCyR(IL-10R2), which previously was considered not to induce signal transduction, led to induction of signal transduction. Interestingly, the SyCyR(IL-10R2) and SyCyR(IL-22Rα1) constructs could form functional heterodimeric receptor signaling complexes with the synthetic IL-6 receptor chain SyCyR(gp130). In summary, we have demonstrated that IL-22 signaling can be phenocopied by synthetic cytokine receptors, identified a functional IL-10R2 homodimeric receptor complex, and uncovered broad receptor cross-talk of IL-22Rα1 and IL-20R2 with gp130.

Heat Capacity Changes (ΔCp) for Interconversions between Differentially-Ordered DNA States within Physiological Temperature Domains: Implications for Biological Regulatory Switches.

Knowledge of differences in heat capacity changes (ΔCp) between biopolymer states provides essential information about the temperature dependence of the thermodynamic properties of these states, while also revealing insights into the nature of the forces that drive the formation of functional and dysfunctional biopolymer "order." In contrast to proteins, for nucleic acids there is a dearth of direct experimental determination of this information-rich parameter, a deficiency that compromises interpretations of the ever-increasing thermodynamic analyses of nucleic acid properties; particularly as they relate to differential nucleic acid (meta)stability states and their potential biological functions. Here we demonstrate that such heat capacity differences, in fact, exist not only between traditionally measured native to fully unfolded (assumed "random coil") DNA states, but also between competing order-to-order transformations. We illustrate the experimental approach by measuring the heat capacity change between "native"/ordered, sequence homologous, "isomeric" DNA states that differ in conformation but not sequence. Importantly, these heat capacity differences occur within biologically relevant temperature ranges. In short, we describe a new and general method to measure the value of such heat capacity differences anywhere in experimentally accessible conformational and temperature space; in this case, between two metastable bulge loop states, implicated in DNA expansion diseases, and their competing, fully paired, thermodynamically more stable duplex states. This measurement reveals a ΔCp of 61 ± 7 cal molbp -1 K -1. Such heat capacity differences between competing DNA "native" ensemble states must be considered when evaluating equilibria between different DNA "ordered" conformations, including the assessment of the differential stabilizing forces and potential biological functions of competing DNA "structured" motifs.

Kinetic Analysis of the Early Signaling Steps of the Human Chemokine Receptor CXCR4.

G protein–coupled receptors (GPCRs) are biologic switches that transduce extracellular stimuli into intracellular responses in the cell. Temporally resolving GPCR transduction pathways is key to understanding how cell signaling occurs. Here, we investigate the kinetics and dynamics of the activation and early signaling steps of the CXC chemokine receptor (CXCR) 4 in response to its natural ligands CXC chemokine ligand (CXCL) 12 and macrophage migration inhibitory factor (MIF), using Förster resonance energy transfer–based approaches. We show that CXCR4 presents a multifaceted response to CXCL12, with receptor activation (≈0.6 seconds) followed by a rearrangement in the receptor/G protein complex (≈1 seconds), a slower dimer rearrangement (≈1.7 seconds), and prolonged G protein activation (≈4 seconds). In comparison, MIF distinctly modulates every step of the transduction pathway, indicating distinct activation mechanisms and reflecting the different pharmacological properties of these two ligands. Our study also indicates that CXCR4 exhibits some degree of ligand-independent activity, a relevant feature for drug development.SIGNIFICANCE STATEMENTThe CXC chemokine ligand (CXCL) 12/CXC chemokine receptor (CXCR) 4 axis represents a well-established therapeutic target for cancer treatment. We demonstrate that CXCR4 exhibits a multifaceted response that involves dynamic receptor dimer rearrangements and that is kinetically embedded between receptor–G protein complex rearrangements and G protein activation. The alternative endogenous ligand macrophage migration inhibitory factor behaves opposite to CXCL12 in each assay studied and does not lead to G protein activation. This detailed understanding of the receptor activation may aid in the development of more specific drugs against this target.

Use and Switching of Biologic Therapy in Patients with Non-Radiographic Axial Spondyloarthritis: A Patient and Provider Survey in the United States.

IntroductionThe Food and Drug Administration (FDA) approved certolizumab-pegol, the first biologic for the treatment of non-radiographic axial spondyloarthritis (nr-axSpA), for use in the United States (US) in March of 2019. The objective of this study was to investigate biologic use and reasons for switching therapy among patients with nr-axSpA in the US.MethodsThis was a real-world, cross-sectional study of rheumatologists conducted in the US. Data were collected from June to August of 2018 via rheumatologist-completed patient record forms. Data from patients who had a rheumatologist-confirmed diagnosis of nr-axSpA were included in the study. Rheumatologists provided information on current medication use and reasons for switching biologics.ResultsEighty-eight rheumatologists collected data on 495 nr-axSpA patients. Over half of nr-axSpA patients were male (53.3%), with a mean age of 44.2 years, and 69.8% of patients reported working full-time. Of the 495 nr-axSpA patients, 48.1% were receiving a biologic and no conventional synthetic disease-modifying anti-rheumatic drug (csDMARD), 18.4% csDMARD (no biologic), 18.2% non-steroidal anti-inflammatory drug (NSAIDs)/COX-2 (no biologic or csDMARD), 11.5% a biologic and a csDMARD, 2.0% were receiving no therapy, and 1.8% other therapy (no biologic, csDMARD, or NSAID/COX-2). Of 295 patients receiving a biologic, 77.8% were receiving their first, 13.8% their second, and 8.3% their third or more biologic. Of 74 nr-axSpA patients who switched from a previous biologic to their current biologic, rheumatologists reported that 51.4% switched due to condition worsening, 48.6% had a loss of response over time, 27.0% switched due to a lack of pain alleviation, and 25.7% of patients switched because remission was not induced.ConclusionsThis study suggests that around 60% of nr-axSpA patients were receiving biologic therapy prior to the approval of certolizumab pegol. Switching of biologics is frequent in nr-axSpA patients and is usually due to lack of efficacy, loss or response, and effort to accomplish remission.

Sustainability and switching of biologics for psoriasis

<p class="abstract"><strong>Background:</strong> The optimal treatment guidelines for psoriasis using biologics are limited. In addition to this, the administration of the original biologic may be terminated or switched to another biologic due to inefficacy, adverse effects, and economic burden. Our objective is to compare demographic characteristics between switched and non-switched groups and to identify the reason for switching among various original biologics in our setup.</p><p class="abstract"><strong>Methods:</strong> We performed a retrospective cohort analysis of psoriatic patients on biologic treatment. Our analysis involved 42 patients, of which 19 were switched to the second biologic. The demographic characteristics and reason for biologic switching were noted and data analyzed between switched and non-switched groups.<strong></strong></p><p class="abstract"><strong>Results:</strong> First line therapies were infliximab (IFX, n=10), etanercept (ETN, n=21), secukinumab (SEC, n=11) and switching required in 3 (30%), 11 (52%), 5 (45%) patients respectively. The reason for switching, in general, in our setup is inefficacy (n=10; 53%), non-availability (n=8; 42%) and adverse event (n=1; 5%). Small number of patients, single-centre study and retrospective design were the limitations.</p><p class="abstract"><strong>Conclusions:</strong> Infliximab showed the least tendency to switch to the second biologic, however, it had adverse reactions. Inefficacy is the primary cause of switching. To the best of our knowledge, our study on Biologics switching is the first of its kind in the Indian scenario.</p>

Multimerization strategies for efficient production and purification of highly active synthetic cytokine receptor ligands.

Cytokine signaling is transmitted by cell surface receptors which act as natural biological switches to control cellular functions such as immune reactions. Recently, we have designed synthetic cytokine receptors (SyCyRs) consisting of green fluorescent protein (GFP)- and mCherry-nanobodies fused to the transmembrane and intracellular domains of cytokine receptors. Following stimulation with homo- and heterodimeric GFP-mCherry fusion proteins, the resulting receptors phenocopied signaling induced by physiologically occurring cytokines. GFP and mCherry fusion proteins were produced in E. coli or CHO-K1 cells, but the overall yield and stability was low. Therefore, we applied two alternative multimerization strategies and achieved immunoglobulin Fc-mediated dimeric and coiled-coil GCN4pII-mediated trimeric assemblies. GFP- and/or mCherry-Fc homodimers activated synthetic gp130 cytokine receptors, which naturally respond to Interleukin 6 family cytokines. Activation of these synthetic gp130 receptors resulted in STAT3 and ERK phosphorylation and subsequent proliferation of Ba/F3-gp130 cells. Half-maximal effective concentrations (EC50) of 8.1 ng/ml and 0.64 ng/ml were determined for dimeric GFP-Fc and mCherry-Fc, respectively. This is well within the expected EC50 range of the native cytokines. Moreover, we generated tetrameric and hexameric GFP-mCherry-Fc fusion proteins, which were also biologically active. This highlighted the importance of close juxtaposition of two cytokine receptors for efficient receptor activation. Finally, we used a trimeric GCN4pII motif to generate homo-trimeric GFP and mCherry complexes. These synthetic cytokines showed improved EC50 values (GFP3: 0.58 ng/ml; mCherrry3: 0.37 ng/ml), over dimeric Fc fused variants. In conclusion, we successfully generated highly effective and stable multimeric synthetic cytokine receptor ligands for activation of synthetic cytokine receptors.

Frequency of biologic switching and the outcomes of switching in children and young people with juvenile idiopathic arthritis: a national cohort study.

SummaryBackgroundInformation is scarce about biological disease-modifying antirheumatic drug (DMARD) switching patterns in children and young people (aged ≤16 years) with juvenile idiopathic arthritis in an era of many biologic therapies. The best choice of biologic to use if the first biological DMARD is not beneficial also remains unclear. We aimed to quantify and characterise biologic switching patterns in children and young people with juvenile idiopathic arthritis, and to compare the effectiveness of using a second tumour necrosis factor inhibitor (TNFi) versus non-TNF is following failure of a first TNFi biologic in routine clinical practice.MethodsOur study population comprised patients with juvenile idiopathic arthritis who were enrolled in two parallel UK cohort studies (the British Society for Paediatric and Adolescent Rheumatology Etanercept Cohort Study [BSPAR-ETN] and the Biologics for Children with Rheumatic Diseases [BCRD] study) between Jan 1, 2004, and April 11, 2019. Data on disease characteristics and DMARD therapy were collected at the time of initiation of a first biologic, at 6 months, at 1 year, and annually thereafter. Biologic switching patterns were described in all patients who started their first biologic from Jan 1, 2010, onwards. Among patients who started treatment with their first biologic from Jan 1, 2004, onwards, had polyarticular course juvenile idiopathic arthritis (extended oligoarthritis or polyarthritis [positive or negative for rheumatoid factor]), and who had started a second biologic, we assessed changes in outcome variables at 6 months compared with baseline and compared the proportion of patients who achieved an American College of Rheumatology Pediatric (ACR Pedi) 90 response and minimal disease activity at 6 months on the basis of the class of the second biologic (a second TNFi vs non-TNFi biologic). Changes in outcome variables at 6 months were compared using linear regression or logistic regression, adjusted for propensity quintiles to account for confounding by indication. We used multiple imputation to account for missing data.FindingsBetween Jan 1, 2004, and April 11, 2019, 2361 patients were enrolled on initiation of biologic therapy. From Jan 1, 2010, onwards, 1152 patients started their first biologic, most of whom started treatment with TNFis (1050 [91%]). The median follow-up was 2·2 years (IQR 1·1–3·8). During this time, 270 (23%) of 1152 patients started a second biologic, 61 (5%) started a third biologic, and 11 (1%) started a fourth biologic. Among 240 patients with polyarticular-course juvenile idiopathic arthritis, 194 (81%) started a second TNFi and 46 (19%) started a non-TNFi after an initial TNFi had failed. Choice of second treatment (second TNFi vs non-TNFi biologic) did not affect the proportion of patients who achieved an ACR Pedi 90 response (adjusted odds ratio [OR] 2·5, 95% CI 0·8–7·9; p=0·11) or minimal disease activity (adjusted OR 1·6, 95% CI 0·6–3·8; p=0·33).InterpretationFor many children and young people with juvenile idiopathic arthritis, treatment with a first or second biologic is not beneficial. We found no evidence that switching to a second non-TNFi biologic was more beneficial than a second TNFi.FundingVersus Arthritis and The British Society for Rheumatology.

P452 Biologic use patterns and predictors for non-persistence and switching of biologics in patients with inflammatory bowel disease: a nationwide population-based study

Abstract Background Data on real-life patterns of biologic use for inflammatory bowel disease (IBD) are scarce. We aimed to examine the patterns of biologic use and the factors associated with non-persistence and switching of biologics in Korean IBD patients. Methods Using National Health Insurance claims, we collected data on patients who were diagnosed with IBD and exposed to biologics between 2010 and 2016. Results Among 1838 patients with Crohn’s disease (CD), 1237 and 601 started with infliximab and adalimumab, respectively. Among 1125 patients with ulcerative colitis (UC), 774, 294, and 57 initiated infliximab, adalimumab, and golimumab, respectively. Rates of non-persistence and switching were higher in UC than in CD. One- and 3-year non-persistence rates were 14.2% and 26.5% in CD and 35.4% and 53.4% in UC, respectively. One- and 3-year switching rates were 3.7% and 10.1% in CD and 15.6% and 22.0% in UC, respectively. In both CD and UC, infliximab and adalimumab initiators showed similar persistence rates, whereas adalimumab initiators had a higher risk of switching than infliximab initiators. In UC, golimumab initiators had a higher risk of non-persistence and switching than infliximab initiators. Steroid use at biologic initiation was associated with an increased risk of non-persistence and switching in both CD and UC. UC patients who started biologic treatment at tertiary hospitals were more likely to continue treatment than those who started at general hospitals/community hospitals/clinics. Conclusion In real-world clinical practice settings, discontinuation of biologics occurred frequently in IBD patients, and switching of biologics was common in UC patients.

P505 Different failure rates after non-medical switching of 744 patients from adalimumab originator to 2 different adalimumab biosimilars at Cambridge University Hospitals, UK: real-world experience

Abstract Background Biosimilar adalimumab became available in the UK in October 2018, with payers introducing a series of measures to drive the adoption of the ‘best value’ adalimumab.1 Consideration of value should include risk of loss of efficacy and adverse reactions, which might drive further biologic switches or ‘reverse switches’ to originator. Managing potential ‘nocebo effect’ requires high levels of patient engagement, whilst the presence or absence of citrate buffer may affect patient-reported discomfort, hence patient treatment perceptions. Methods Patients were switched to 2 different biosimilar adalimumabs, one buffered with citrate (ADA1) and one in a citrate-free buffer (ADA2). The choice of adalimumab biosimilar was made for clinical and economic reasons. Patients were informed of the switch to either ADA1 or ADA2 in advance via letter and at clinic visits. Patients who reported problems after switching were reviewed. Results A total of 744 patients were switched from originator adalimumab (ADA0) to ADA1 or ADA2. Rheumatology and dermatology patients were switched to ADA1, whilst gastroenterology patients were switched to ADA2, except for those with a latex allergy, where ADA1 was used (or ADA2 in a latex-free syringe). A total of 49 (6.6%) patients reported problems and a further switch of drug was judged necessary in 48 (Table 1). Switch failure was significantly more likely with ADA1 than ADA2 (7.7% vs. 1.8%; p = 0.006). The median time to switch failure was 97 days (range 5–196 days). The commonest reason for switch failure was disease flare (23 patients, 48%), followed by injection site pain or reaction (21 patients, 44%). Disease flare and injection site problems were more likely to be reported with ADA1 than ADA2 (flare: 23/583 vs. 0/161, p = 0.008; injection site pain 20/583 vs. 1/161, p = 0.06). For patients reporting disease flare, clinicians tended to select a reverse switch to ADA0, whilst for those with injection site problems, a further switch to a different biosimilar was the preferred approach; both strategies were effective at recapture. Conclusion In the context of an effective patient communication strategy, adalimumab biosimilar switching was associated with overall low rates of patient-reported problems in a large cohort. Despite an identical communication strategy, significantly higher rates of injection site problems and disease flares were seen between 2 different biosimilars, reflected in a higher need for further switches. These differences may impact the cost-effectiveness of any chosen strategy. Reference

P549 A virtual clinic enhances the quality use of anti-TNF dose intensification and rates of treatment success using a treat-to-target approach compared with standard outpatient care in Crohn’s disease

Abstract Background Virtual clinics (VC) represent a novel model-of-care which promote quality use of biologics and facilitate a treat-to-target (T2T) approach. We aimed to evaluate the clinical and process-driven outcomes of intensified anti-TNF therapy for secondary loss of response (SLoR) in a VC compared with standard outpatient care (SoC). Methods A retrospective multicenter, parallel observational cohort study of patients with Crohn’s disease (CD) who underwent anti-TNF dose intensification to address SLoR with up to 2-years of follow-up was undertaken. Objective assessments of disease activity and anti-TNF trough levels at SLoR then during subsequent 6-month semesters were compared longitudinally between VC and SoC groups. ‘Anti-TNF escalation success’ was the primary endpoint, defined as achieved when two consecutive 6-month semesters of objective assessment demonstrated inactive disease. Dose intensification was defined as ‘appropriate’ if there was both objective evidence of disease activity, plus anti-TNF trough levels at or below the lower limit of the therapeutic range prior to intensification. ‘Treatment escalation failure’ was defined by the occurrence of one or more of biologic switching, discontinuation or further intensification; recommencement of corticosteroids, or IBD-related surgery. Results 149 patients (69 VC vs. 80 SoC) underwent infliximab (n = 94) or adalimumab (n = 55) dose intensification with similar baseline patient, disease and treatment characteristics between cohorts. The median duration of follow-up post dose-intensification was 1.9 and 1.5 years for the SoC and VC cohorts respectively (p = 0.37). There were higher rates of appropriate dose intensification (82.6 vs. 40.0%, p < 0.01) across the VC cohort. Higher proportions of anti-TNF escalation success (60.9 v 35.0%, p < 0.01), biomarker remission (i.e., C-Reactive Protein (<5mg/l) and faecal calprotectin (<150 μg/ml) normalisation, log-rank tests, p = 0.06 and p < 0.01 respectively), tight disease monitoring (84.1 vs. 28.8%, p < 0.01) and de-escalation of intensified therapy (21.3 vs. 10.0%, p = 0.03) were also achieved by the VC cohort following dose-intensification. Conclusion This study favoured a VC-led model of care over standard outpatient-based IBD care in facilitating an effective T2T approach to CD management. A VC model of care improved quality use of intensified anti-TNF therapy through processes that promoted appropriate dose intensification and encouraged more frequent anti-TNF dose de-escalation. Moreover, tight semester-based monitoring using a T2T-based strategy facilitated by the VC was associated with improved treatment outcomes.

Mathematical modelling of a microRNA-regulated gene network in Caenorhabditis elegans.

MicroRNAs are known to regulate gene expression either by repressing translation or by directing sequence-specific degradation of target mRNAs, and are therefore considered to be key regulators of gene expression. A gene-regulatory pathway involving heterochronic genes controls the temporal pattern of Caenorhabditis elegans postembryonic cell lineages. Based on experimental data, we propose and analyze a mathematical model of a gene-regulatory module in this nematode involving two heterochronic genes, lin-14 and lin-28, which are both regulated by lin-4, encoding a microRNA. The conditions under which the model experiences bifurcations are investigated. We determine the parameter regimes for which the system exhibits monostability and bistability, the latter associated with a biological switch. We observe in particular that bistability occurs without co-operativity, in keeping with knowledge about the regulatory behaviour of lin-14 and lin-28. The analytical results are confirmed by numerical simulations that illustrate how the microRNA lin-4 plays a crucial role in determining of the qualitative dynamics of the model.

Severe asthma in the US population and eligibility for mAb therapy

Severe asthma in the US population and eligibility for mAb therapy

Detection of biological switches using the method of Gr\xf6ebner bases

BackgroundBistability and ability to switch between two stable states is the hallmark of cellular responses. Cellular signaling pathways often contain bistable switches that regulate the transmission of the extracellular information to the nucleus where important biological functions are executed.ResultsIn this work we show how the method of Gröebner bases can be used to detect bistability and output switchability. The method of Gröebner bases can be seen as a multivariate, non-linear generalization of the Gaussian elimination for linear systems which conveniently seperates the variables and drastically simplifies the simultaneous solution of polynomial equations. A necessary condition for fixed-point state bistability is for the Gröbner basis to have three distinct solutions for the state. A sufficient condition is provided by the eigenvalues of the local Jacobians. We also introduce the concept of output switchability which is defined as the ability of an output of a bistable system to switch between two different stable steady-state values. It is shown that bistability does not necessarily guarantee switchability of every state variable of the system. We further show that, for a bistable system, the necessary conditions for output switchability can be derived using the Gröebner basis. The theoretical results are incorporated into an analysis procedure and applied to several systems including the AKT (Protein kinase B), RAS (Rat Sarcoma) and MAPK (Mitogen-activated protein kinase) signal transduction pathways. Results demonstrate that the Gröebner bases can be conveniently used to analyze biological switches by simultaneously detecting bistability and output switchability.ConclusionThe Gröebner bases provides a novel methodology to analyze bistability. Results clarify the distinction between bistability and output switchability which is lacking in the literature. We have shown that theoretically, it is possible to have an output subspace of an n-dimensional bistable system where certain variables cannot switch. It is possible to construct such systems as we have done with two reaction networks.

Phase Change Biological Switch: A New Hypothesis on the Mechanism of Cancer Formation

Phase Change Biological Switch: A New Hypothesis on the Mechanism of Cancer Formation

Anti-adalimumab antibodies kinetics: an early guide for juvenile idiopathic arthritis (JIA) switching.

To assess the longitudinal production of anti-adalimumab antibody (AAA) and baseline risk factors for this antibody development in juvenile idiopathic arthritis (JIA) patients initiating adalimumab (ADA). Thirty consecutive JIA patients under ADA therapy were prospectively followed. JIA clinical/laboratorial/treatment data and sera for ADA and AAA assays (ELISA and bridging ELISA) were obtained at baseline (BL), 2 months (2M), 3 months (3M), 6 months (6M), 12 months (12M), and 24 months (24M). Patients with therapy failure requiring ADA withdrawn had their sera evaluated at their last medical visit prior to biologic switch (blinded to ADA and AAA levels). AAA was absent at BL, first detected at 2M after ADA initiation in 2/30 (7%) patients with a significant increase at 3M (10/29 (34%), p = 0.013) and no major change in 6M (11/30 (37%)) and 12M (9/26 (35%)). Of note, at 3M, AAA levels correlated negatively with ADA levels (r = - 0.781, p = 0.0001). Analysis of BL predictors revealed a significantly higher risk of developing AAA in patients with female gender (OR 21; 95% CI 1.08-406.57; p = 0.044), ESR > 30 mm/1st hour (OR 5.44; 95% CI 1.04-28.53; p = 0.045), and leflunomide use (OR 9.33; 95% CI 1.51-57.66; p = 0.016). In contrast, concomitant use of methotrexate was protective for AAA appearance (OR 0.08; 95% CI 0.01-0.53; p = 0.009). After 12M of ADA, 60% of AAA-positive patients required drug switch for drug failure compared with 15% in AAA-negative group (p = 0.03). This study provides novel evidence of AAA production kinetics demonstrating a timely significant increase starting at 3M and stable throughout 24M. We also identified female gender, increased ESR, and leflunomide use as relevant risk factors for AAA production at BL, whereas methotrexate was protective. Early systematic monitoring of AAA at 3M may, therefore, guide drug switching in these patients.Key Points• Anti-adalimumab antibodies (AAA) production kinetics demonstrated a timely significant increase starting at 3M in juvenile idiopathic arthritis (JIA) patients under adalimumab therapy• Female gender, increased ESR, and leflunomide use were identified as relevant risk factors for AAA production in JIA, whereas methotrexate was protective.

PMS64 ASSESSING THE QUALITY OF BIOLOGIC SWITCH DECISIONS IN PSORIATIC ARTHRITIS: VALIDATION OF PASQAL - AN OUTCOMES MEASUREMENT TOOL

Switching between biologics is a recommended strategy for Psoriatic Arthritis (PsA), with the target being remission or low disease activity, and improved disease management. Biologic switch assessment is therefore of utmost relevance in order to maximize outcomes. This study aims to validate an outcomes measurement tool named PASQAL (Psoriatic Arthritis Switch Quality Assessment tooL). PASQAL was recently created to evaluate the quality of biologic switch in PsA patients with peripheral (pPASQAL) and axial (axPASQAL) phenotypes. For PASQAL’s validation, 12 experienced rheumatologists were asked to evaluate and classify the biologic switch of 80 clinical cases (40 with peripheral PsA and 40 with axial PsA). Clinical judgement was defined as the “gold standard” against which the tools’ output was compared. Each clinical case was evaluated by 3 experts and only those with consensual clinical judgement (agreement between at least 2 out of 3 rheumatologists) were included in the validation analysis. The results were used to assess its validity, through sensitivity/specificity analysis, and reliability, through the level of agreement between the tool and the clinical judgement measured by Cohen’s kappa. 75%(30/40) of peripheral PsA and 63%(25/40) of axial PsA switch scenarios reached agreement between rheumatologists and were, therefore, used for PASQAL’s validation. pPASQAL and axPASQAL were more sensitive upon “Good” quality level (92% and 100%), while more specific for the “Insufficient” quality level (97% and 100%). Concerning reliability, good agreement levels were obtained for both tools (k=0.87 pPASQAL;k=0.71 axPASQAL). PASQAL aims for higher standards of care, given that the likelihood of classifying a given switch as “Good” is lower than the rheumatologists’ classification (-25% to -33%). PASQAL’s validation provided evidence regarding tools’ validity and reliability for both phenotypes. These fully developed and validated tools may support rheumatologists in making more informed therapeutic decisions and be used on real-world research.

PBI83 GOLIMUMAB IMPROVES QUALITY OF LIFE AND OTHER PATIENT-REPORTED OUTCOMES IN PATIENTS WITH RHEUMATOID ARTHRITIS, IN REAL-WORLD CONDITIONS

To assess the impact of golimumab on quality-of-life (QoL) and other patient-reported outcomes in patients with rheumatoid arthritis (RA) in real-world settings. GO-Q was an observational, prospective, 12-month study conducted in Greece, in naïve to golimumab patients with moderate-to-severe active RA; patients previously treated with >1 biologic (b)DMARDs or switching anti-TNFs were excluded. Primary endpoint: the impact of golimumab on QoL at 3/6/12 months, by the EQ-5Q-3L questionnaire. Other endpoints assessed the impact of golimumab on disease activity (Disease Activity Score for 28 joints with erythrocyte sedimentation rate [DAS28-ESR]), physical function (Health Assessment Questionnaire–Disability Index [HAQ-DI]), and work productivity/activity impairment (by Work Productivity and Activity Impairment questionnaire [WPAI] for RA), at 3/6/12 months respectively. Non-parametric tests were used for all comparisons. A total of 145 patients were enrolled (age and disease duration [mean±sd]: 54.6±12.2 and 4.6±5.1 years, respectively). At baseline, 78.6% of patients were bDMARD-naïve, 87.6% had received conventional synthetic (cs)DMARDs and 77.2% corticosteroids. During follow-up, golimumab was mostly (99.4%) administered in the 50mg once-monthly dose, plus background csDMARDs. Improvements in EQ-5D-3L UK index scores from baseline to 3/6/12 months were: 0.21±0.24, 0.28±0.25, 0.38±0.30, respectively (p<0.001, all comparisons). DAS28-ESR scores improved from baseline to 3/6/12 months; mean±sd scores were 5.4±0.9, 4.1±1.2, 3.7±1.2 and 3.2±1.1, respectively (p<0.001, all comparisons). Of patients attending the 12-month visit, 27.3% and 54.6% achieved DAS28-ESR<2.6 (remission) and DAS28-ESR≤3.2 (low disease activity). Improvements were observed in HAQ-DI and WPAI scores from baseline to 3/6/12 months (p<0.001, all comparisons). Mean adherence rate to golimumab was 90.3%; non-significant difference in adherence rates for bDMARD-naïve vs. -experienced (p=0.152). Healthcare resources for RA-related reasons were utilised by >93.2% of pts. In real-world settings, patients with RA receiving golimumab over 12 months experienced significant improvements in QoL, physical function and work productivity/activity impairment.

Notch pathway: a bistable inducer of biological noise?

Notch signalling pathway is central to development of metazoans. The pathway codes a binary fate switch. Upon activation, downstream signals contribute to resolution of fate dichotomies such as proliferation/differentiation or sub-lineage differentiation outcome. There is, however, an interesting paradox in the Notch signalling pathway. Despite remarkable predictability of fate outcomes instructed by the Notch pathway, the associated transcriptome is versatile and plastic. This inconsistency suggests the presence of an interface that compiles input from the plastic transcriptome of the Notch pathway but communicates only a binary output in biological decisions. Herein, we address the interface that determines fate outcomes. We provide an alternative hypothesis for the Notch pathway as a biological master switch that operates by induction of genetic noise and bistability in order to facilitate resolution of dichotomous fate outcomes in development.Graphical abstract

Knowledge Objects of Synthetic Biology: From Phase Transitions to the Biological Switch

Following Hans-Jorg Rheinberger’s epistemological concept we show how a generic element of synthetic biology, the “biological switch”, can be integrated into an experimental system. Here synthetic biology is assumed to be a technoscience. Hence, the biological switch becomes a technoscientific research object. Consequently, the experimental system has to be analyzed in a technoscientific experimental setting, showing differences in comparison with the former. To work out the specific properties of the technoscientific experimental system, biological switching behavior (bistability) is compared with the scientific research object laser light in its classical setting. For the analyses, both the laser light and bistability, enabling a biological switch, are considered as epistemic things connected by the same theoretical concept of phase transitions. The so-called Schlogl model is used to model both biological switching behavior and induced emission of radiation and becomes an epistemic thing in itself. It becomes clear that the answer, whether one is dealing with the emission of laser light or with bistable switching behavior, is linked to the perspective taken. The technoscientific orientation towards applications and the development of basic scientific theories require different perspectives on one and the same epistemic thing, here also represented by the model. The research objects of synthetic biology as a technoscience thus also enter into the corresponding experimental systems as techno-epistemic objects. (Please note especially footnote 4 for an explanation and the differentiation of the used notions of “research object”, “knowledge object” or “object of knowledge”, “object of interest” and “epistemic thing” and “techno-epistemic object”. A clarification of the way how these notions are used is essential for further reading.) Their analysis leads to a more complete understanding of what constitutes synthetic biology.

On a Robust, Sensitive Cell-Free Method for Pseudomonas Sensing and Quantification in Microfluidic Templated Hydrogels.

Through the use of droplet microfluidics to integrate cell-free activity into inert hydrogel beads, we have developed a platform that can perform biologically relevant functions without the need for cells. Specifically, cell-free lysates serve a utility in performing cellular functions and providing biologically relevant metabolic products without requiring the optimal biological conditions for cell growth and proliferation. By teasing out specific biological components that enable transcription and translation to occur, these cell-like functions can be reconstituted in vitro without requiring the entire cell and milieu of cellular organelles. This enables the optimization of synthetic biological circuits, either by concentration or logic switches, simply through the addition or removal of genetic components (plasmids, inducers, or repressors) of regulatory elements. Here, we demonstrate an application of cell-free processes that is robust and portable, independent of a substrate, to apply for sensing and reporting functions of a quorum-sensing molecule N-3-oxododecanoyl homoserine lactone (3OC12HSL) found crucial for pathological Pseudomonas aeruginosa infection. We develop an agarose bead platform that is easily adaptable and simply programmable to fit a variety of biological and chemical sensing applications for the utility of ease of delivery and activation in remote environments—even in conditions with very little hydration.