Effects of Platelet Agonists and Priming on the Formation of Platelet Populations

Platelets from healthy donors display heterogeneity in responsiveness to agonists. The response thresholds of platelets are controlled by multiple bioactive molecules, acting as negatively or positively priming substances. Higher circulating levels of priming substances adenosine and succinate, as well as the occurrence of hypercoagulability, have been described for patients with ischaemic heart disease. Here, we present an improved methodology of flow cytometric analyses of platelet activation and the characterisation of platelet populations following activation and priming by automated clustering analysis.Platelets were treated with adenosine, succinate, or coagulated plasma before stimulation with CRP-XL, 2-MeSADP, or TRAP6 and labelled for activated integrin αIIbβ3 (PAC1), CD62P, TLT1, CD63, and GPIX. The Super-Enhanced Dmax subtraction algorithm and 2% marker (quadrant) setting were applied to identify populations, which were further defined by state-of-the-art clustering techniques (tSNE, FlowSOM).Following activation, five platelet populations were identified: resting, aggregating (PAC1 + ), secreting (α- and dense-granules; CD62P + , TLT1 + , CD63 + ), aggregating plus α-granule secreting (PAC1 + , CD62P + , TLT1 + ), and fully active platelet populations. The type of agonist determined the distribution of platelet populations. Adenosine in a dose-dependent way suppressed the fraction of fully activated platelets (TRAP6 > 2-MeSADP > CRP-XL), whereas succinate and coagulated plasma increased this fraction (CRP-XL > TRAP6 > 2-MeSADP). Interestingly, a subset of platelets showed a constant response (aggregating, secreting, or aggregating plus α-granule secreting), which was hardly affected by the stimulus strength or priming substances.

Environment dependent benefits of individual differences in the recruitment behaviour of honey bees

Inter-individual differences in behaviour within the members of a social group can affect the group's productivity. In eusocial insects, individual differences amongst workers in a colony play a central role division of labour and task allocation. Extensive empirical and theoretical work has highlighted variation in response thresholds as a proximate mechanism underlying individual behavioural differences and hence division of labour. However, other response parameters, like response probability and intensity, can affect these differences. In this study, we first extended a previously published agent-based model on honey bee foraging to understand the relative importance of response (dance) probability and response (dance) intensity in the task of recruitment. Comparing variation obtained from the simulations with previously published empirical data, we found that response intensity plays a more important role than probability in producing consistent inter-individual differences in recruitment behaviour. We then explored the benefits provided by this individual variation in recruitment behaviour to the colony's collective foraging effort under different environmental conditions. Our results revealed that individual variation leads to a greater energetic yield per forager, but only when food is abundant. Our study highlights the need to consider all response parameters while studying division of labour and adds to the growing body of evidence linking individual variation in behavioural responses to the success of social groups.

eABR THR Estimation Using High-Rate Multi-Pulse Stimulation in Cochlear Implant Users

We estimated the electrically-evoked auditory brainstem response thresholds (eABR THRs) in response to multi-pulses with high burst rate of 10,000 pulses-per-second (pps). Growth functions of wave eV amplitudes, root mean square (RMS) values, peak of phase-locking value (PLV), and the lowest valid data point (LVDP) were calculated in 1-, 2-, 4-, 8-, and 16-pulses conditions. The growth functions were then fitted and extrapolated with linear and exponential functions to find eABR THRs. The estimated THRs were compared to psychophysical THRs determined for multi-pulse conditions as well as to the clinical THRs measured behaviorally at the rate of 1,000 pps. The growth functions of features showed shallower growth slopes when the number of pulses increased. eABR THRs estimated in 4-, 8-, and 16-pulses conditions were closer to the clinical THRs, when compared to 1- and 2-pulses conditions. However, the smallest difference between estimated eABR THRs and clinical THRs was not always achieved from the same number of pulses. The smallest absolute difference of 30.3 μA was found for the linear fittings on growth functions of eABR RMS values in 4-pulses condition. Pearson’s correlation coefficients (PCCs) between eABR THRs and psychophysical THRs were significant and relatively large in all but 16-pulses conditions. The PCCs between eABR THRs and clinical THRs, however, were smaller and in less cases significant. Results of this study showed that eABRs to multi-pulse stimulation could, to some extent, represent clinical stimulation paradigms, and thus in comparison to single pulses, could estimate clinical THRs with smaller errors.

An oxytocin/vasopressin-related neuropeptide modulates social foraging behavior in the clonal raider ant

Oxytocin/vasopressin-related neuropeptides are highly conserved and play major roles in regulating social behavior across vertebrates. However, whether their insect orthologue, inotocin, regulates the behavior of social groups remains unknown. Here, we show that in the clonal raider ant Ooceraea biroi, individuals that perform tasks outside the nest have higher levels of inotocin in their brains than individuals of the same age that remain inside the nest. We also show that older ants, which spend more time outside the nest, have higher inotocin levels than younger ants. Inotocin thus correlates with the propensity to perform tasks outside the nest. Additionally, increasing inotocin pharmacologically increases the tendency of ants to leave the nest. However, this effect is contingent on age and social context. Pharmacologically treated older ants have a higher propensity to leave the nest only in the presence of larvae, whereas younger ants seem to do so only in the presence of pupae. Our results suggest that inotocin signaling plays an important role in modulating behaviors that correlate with age, such as social foraging, possibly by modulating behavioral response thresholds to specific social cues. Inotocin signaling thereby likely contributes to behavioral individuality and division of labor in ant societies.

AB0558 CLINICAL EFFECTIVENESS AND SAFETY OF ADALIMUMAB VERSUS NON-BIOLOGIC THERAPY IN PSORIATIC ARTHRITIS PATIENTS OVER 24 MONTHS – RESULTS OF THE COMPLETE-PsA CANADIAN OBSERVATIONAL STUDY

Background:COMPLETE-PsA was an observational study of biologic-naïve Canadian adults with active psoriatic arthritis (PsA) treated with adalimumab or non-biologic disease-modifying anti-rheumatic drugs (nbDMARD) after switch from initial therapy.Objectives:The aim of this analysis was to assess the 24-month clinical effectiveness and safety of adalimumab vs. nbDMARD in the treatment of PsA in a real-life setting.Methods:Eligible patients were biologic naïve adults, with active PsA who required change in their treatment regimen due to inadequate response or intolerance, per the judgment of the treating physician. Patients were enrolled between July/2011 and December/2017 and followed for up to 24 months. Patients were treated as per routine care. The primary endpoint, change in DAS-28 to month 24, was assessed with baseline-adjusted multivariable models and the least square mean (LSM) estimates were generated; Physician’s Global Assessment of disease activity (PGA, 100mm VAS) was assessed using similar methodology. Probability of achieving the following therapeutic response thresholds was ascertained and odds ratios (ORs) were generated: 50%/70% improvement in the American College of Rheumatology criteria (ACR50/ACR70), DAS-28<3.2 (low disease activity or remission; LDA/remission), DAS-28<2.6 (remission), modified minimal disease activity (mMDA: achievement of 5/7 of: TJC and SJC ≤1 each, BSA ≤3%, pain ≤15 (VAS, mm), Patient Global Assessment [PtGA] ≤20, HAQ-DI ≤0.5, and no enthesitis), and psoriasis (PsO) BSA <3%.Results:A total of 277 adalimumab and 148 nbDMARD- treated patients were included as part of the intent-to-treat population. Baseline methotrexate was reported by 61.7% and 81.1% of adalimumab and nbDMARD-treated patients, respectively. PsO BSA at baseline was predominantly <3% for both adalimumab (60.2%) and nbDMARD (64.6%) patients. Adalimumab-treated patients reported significantly (p<0.05) higher mean (SD) disease activity for both DAS-28 [4.8 (1.2) vs. 4.3 (1.1)] and PGA [59.4 (19.5) vs. 51.0 (21.8) mm] at baseline.For the primary endpoint, baseline-adjusted month 24 DAS-28 levels were significantly lower for adalimumab vs. nbDMARD patients [LSM (95%CI): 2.4 (2.2-2.6) vs. 3.0 (2.7-3.3); p=0.037]. In addition, rapid and sustained reductions in DAS-28 were observed for adalimumab-treatment patients, with overall treatment effect significant (p<0.001) in favor of adalimumab [estimate (95%CI): -1.1 (-1.4, -0.7)]; similar results were observed for PGA [-12.9 (-1.7, -8.0)]. Adalimumab-treated patients were at significantly higher (p<0.001) odds of attaining therapeutic response thresholds compared to DMARD-treated patients, specifically: DAS-28 LDA/remission [OR (95%CI): 4.5 (2.8, 7.3)] or remission [OR (95% CI): 4.1 (2.7-6.3)], ACR50 [OR (95% CI): 3.0 (2.0-4.6)], ACR70 [OR (95% CI): 3.1 (2.0-4.9)], mMDA [OR (95% CI): 2.4 (1.6-3.6)], and PsO BSA <3% [OR (95% CI): 2.2 (1.2-3.7)].Overall, 32 (10.7%) of adalimumab-treated patients reported 86 AEs, the most common related to infections [16 events in 10 (3.3%) patients].Conclusion:Real-world treatment with adalimumab was more effective in improving disease activity and psoriasis severity, over 24 months when compared to nbDMARDs and was associated with significantly greater likelihood of achieving minimal disease activity. Observed AEs were consistent with the established safety profile of adalimumab.Disclosure of Interests:Majed Khraishi Speakers bureau: Speaker for AbbVie, Consultant of: Consultant for AbbVie, Grant/research support from: Principal Investigator for AbbVie, Jacqueline Stewart Speakers bureau: Speaker for Abbvie, Janssen, and Johnson & Johnson, Consultant of: Advisory Board Consultant for AbbVie, Amgen, Celgene, Merck, Novartis, Pfizer, and Sanofi-Genzyme;, Grant/research support from: Participated in research with AbbVie, Bristol Myers Squibb, Janssen, and Roche, Yatish Setty Consultant of: Advisory Board meetings with AbbVie and Janssen, Marie-Claude Laliberté Employee of: Employee of AbbVie, Louis Bessette Speakers bureau: Speaker for Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Celgene, Lilly, Novartis, Gilead, Sandoz, and Fresenius Kabi, Consultant of: Consultant for Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Celgene, Lilly, Novartis, Gilead, Sandoz, Samsung Bioepis, and Fresenius Kabi, Grant/research support from: Investigator for Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Celgene, Sanofi, Lilly, Novartis, and Gilead.

OP0143 IMPACT OF ADALIMUMAB VERSUS NON-BIOLOGIC THERAPY ON DISEASE ACTIVITY AND PATIENT-REPORTED OUTCOMES IN ANKYLOSING SPONDYLITIS OVER 24 MONTHS – RESULTS OF THE COMPLETE-AS CANADIAN OBSERVATIONAL STUDY

Background:COMPLETE-AS was an observational study among Canadian biologic-naïve adults with active ankylosing spondylitis (AS) treated with either adalimumab or subsequent non-biologic disease-modifying anti-rheumatic drugs and/or non-steroidal anti-inflammatory drugs (nbDMARD/NSAID) after having switched from initial treatment with a preceding nbDMARD and/or NSAID due to lack of response or intolerance, as per treating physician judgement.Objectives:To assess the impact of adalimumab on disease activity and patient-reported outcomes among adalimumab- vs. nbDMARD/NSAID-treated patients over 24 months.Methods:Patients were enrolled between July 2011 and December 2017 and followed for up to 24 months. Treatment was per routine care and all analyses were perfomed using the intent-to-treat (ITT) approach. Between-group differences for change in patient-reported disease activity (BASDAI), morning stiffness (minutes/day), functional limitation (BASFI), quality of life (QoL: SF-12), depression (BDI-II), and work productivity (WLQ) were assessed with repeated measures models for overall treatment effect; baseline-adjusted estimates (least square means [LSM]) for each visit were produced. Achievement of, and time to the following endpoints were assessed: 50% improvement from baseline in BASDAI (BASDAI50); minimum clinically important improvements (MCIIs) in BASDAI (Δ≥1.1); BASFI (Δ≥0.6); SF-12 physical component score (PCS; Δ≥4.4) and mental component score (MCS; Δ≥3.1); and low disease activity for BASDAI (<4) and BASFI (<3.8).Results:A total of 452 adalimumab-treated patients and 187 nbDMARD/NSAID-treated patients were enrolled in the study and included in the analyses. At baseline, mean (SD) BASDAI [6.4 (1.8) vs. 5.0 (1.8); p<0.001] and BASFI [5.5 (2.4) vs. 3.7 (2.4)] were however significantly (p<0.001) higher among adalimumab-treated patients compared to nbDMARD/NSAID-treated patients, respectively.Over 24 months, adalimumab-treated patients had significantly lower overall BASDAI scores compared to nbDMARD/NSAID-treated patients [estimate (95% CI): -0.7 (-1.2, -0.3); p=0.007]. BASFI scores were also significantly lower among adalimumab-treated patients over the course of the study [estimate (95% CI): -0.4 (-0.8, 0.0); p=0.013]. Both groups had statistically comparable outcomes for morning stiffness, BDI-II, WLQ, and SF-12.Adalimumab-treated patients were also at significantly higher odds of achieving therapeutic response thresholds, including BASDAI50 [OR (95% CI): 1.7 (1.2-2.3)], BASDAI<4 [1.8 (1.2-2.7)], MCII for BASDAI [1.9 (13.-2.9)], and MCII for BASFI [1.6 (1.1-1.2)]. Time to achievement of each threshold was significantly shorter among adalimumab-treated patients for BASDAI50 [HR (95% CI): 1.8 (1.1-2.8)], BASDAI<4 [1.7 (1.6-3.6)], and MCII for BASDAI [1.5 (1.0-2.3)]. Time to achievement of MCII for BASFI was not statistically different between groups; for BASFI<3.8 and MCII for both SF-12 PCS and MCS, both odds of, and time to achievement, were also statistically comparable.At month 24, baseline-adjusted BASDAI and BASFI was comparable (p>0.05): LSM (95%CI) 3.5 (3.3, 3.8) vs. 3.6 (3.2-4.0), and 2.9 (2.6-3.1) vs. 3.3 (2.9-3.7), respectively, for adalimumab-treated vs. nbDMARD/NSAID-treated patients.Conclusion:Among Canadian patients with active AS, adalimumab-treated patients reported a greater overall reduction in disease burden related to both self-reported disease activity and functional capacity compared to nbDMARD/NSAID-treated patients, along with higher odds and shorter time to achieving therapeutic response thresholds. Despite the overall beneficial effects observed with adalimumab, residual disease burden, however, is observed for Canadian AS patients even after 24 months of treatment.Acknowledgements:The authors wish to acknowledge JSS Medical Research for their contribution to the statistical analysis, medical writing, and editorial support during the preparation of this abstract. AbbVie provided funding to JSS Medical Research for this work.Disclosure of Interests:Louis Bessette Speakers bureau: Speaker for Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Celgene, Lilly, Novartis, Gilead, Sandoz, Fresenius Kabi, Consultant of: Consultant for Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Celgene, Lilly, Novartis, Gilead, Sandoz, Samsung Bioepis, Fresenius Kabi, Grant/research support from: Investigator for Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Celgene, Sanofi, Lilly, Novartis, Gilead, Andrew Chow Speakers bureau: Speaker for AbbVie, BMS, Janssen, Pfizer, Consultant of: Consultant for AbbVie, Amgen, BMS, Celgene, Janssen, Lilly, Merck, Novartis, Pfizer, Roche, Grant/research support from: Investigator for AbbVie, Amgen, BMS, Celgene, Janssen, Lilly, Merck, Novartis, Pfizer, Roche, Viktoria Pavlova Speakers bureau: Speaker for Amgen, Abbvie, BMS, Jenssen, Lilly, Merk, Novartis, Roche, UCB, and Pfizer, Consultant of: Consultant for Amgen, Abbvie, BMS, Jenssen, Lilly, Merk, Novartis, Roche, UCB, and Pfizer, Grant/research support from: Investigator for Janssen, UCB, Abbvie, and Pfizer; and received research grants from UCB, Marie-Claude Laliberté Employee of: Employee of AbbVie, Majed Khraishi Speakers bureau: Speaker for AbbVie, Consultant of: Consultant for AbbVie, Grant/research support from: Principal Investigator for AbbVie

Calibration of cell-intrinsic interleukin-2 response thresholds guides design of a regulatory T cell biased agonist

Interleukin-2 is a pleiotropic cytokine that mediates both pro- and anti-inflammatory functions. Immune cells naturally differ in their sensitivity to IL-2 due to cell type and activation state-dependent expression of receptors and signaling pathway components. To probe differences in IL-2 signaling across cell types, we used structure-based design to create and profile a series of IL-2 variants with the capacity to titrate maximum signal strength in fine increments. One of these partial agonists, IL-2-REH, specifically expanded Foxp3+ regulatory T cells with reduced activity on CD8+ T cells due to cell type-intrinsic differences in IL-2 signaling. IL-2-REH elicited cell type-dependent differences in gene expression and provided mixed therapeutic results: showing benefit in the in vivo mouse dextran sulfate sodium (DSS) model of colitis, but no therapeutic efficacy in a transfer colitis model. Our findings show that cytokine partial agonists can be used to calibrate intrinsic differences in response thresholds across responding cell types to narrow pleiotropic actions, which may be generalizable to other cytokine and growth factor systems.