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INTRODUCTION: In order to tackle the pandemic, governments have established various types of advisory boards to provide evidence and recommendations to policy makers. Scientists working on these boards have faced many challenges, including working under significant time constraints to produce 'evidence' as quickly as possible. However, their voices are still largely missing in the discussion. This study explores the views and experiences of scientists working on government advisory boards during the COVID-19 pandemic, with the aim to learn lessons for future pandemic management and preparedness. METHODS: We conducted online video or telephone semi-structured interviews between December 2020 and April 2021 with 21 scientists with an official government advisory role during the COVID-19 pandemic in Belgium, the Netherlands, UK, Sweden and Germany. The interviews were audio-recorded and transcribed and analysed using a combination of inductive and deductive thematic analysis techniques. RESULTS: Scientists viewed the initial focus on biomedically oriented work during the pandemic as somewhat one-dimensional, but also highlighted difficulties of working in an interdisciplinary way. They found it difficult at times to ensure that the evidence is understood and taken on board by governments. They found themselves taking on new roles, the boundaries of which were not clearly defined. Consequently, they were often perceived and treated as a public figure. CONCLUSION: Scientists working on advisory boards in European countries faced similar challenges, highlighting key lessons to be learnt. Future pandemic preparedness efforts should focus on building interdisciplinary collaboration through development of scientists' skills and appropriate infrastructure; ensuring transparency in how boards operate; defining and protecting the boundaries of the scientific advisor role; and supporting scientists to inform the public in the fight against disinformation, while dealing with potential hostile reactions.

Objectives: To better target new vaccines and treatments being developed for respiratory syncytial virus (RSV) and influenza virus (influenza), we studied the association of age with prevalence, diagnostic features and course of illness of these infections in primary care patients. Methods: Secondary analysis of observational data on the aetiology, diagnosis and prognosis in adults presenting to primary care with acute cough in 12 European countries (2007-2010) using regression analyses corrected for clustering of patients within countries. Age groups were 18-59 years, 60-74 years, and 75 years and older (75+). Results: Nasopharyngeal swabs for 144 (4.6%), 169 (5.4%) and 104 (3.4%) out of 3104 patients were polymerase chain reaction (PCR) positive for RSV, influenza A and influenza B, respectively. RSV prevalence in patients 75+ (8.5%) was twice the prevalence in those under 60 years (4.2%). Influenza prevalence was not associated with age. Diagnostic features for these viruses were not associated with age. Symptom duration was associated with age for RSV and influenza B, but not for influenza A. The odds of unresolved symptoms after 28 days were associated with age for RSV only. Illness deterioration was associated with age for RSV, with patients 75+ at increased risk, but not for influenza. Conclusion: In adults presenting to primary care with acute cough, the diagnostic features of RSV or influenza infection are not associated with age. For RSV both the prevalence and illness course are significantly worse at higher age, for influenza only the illness course is. (C) 2020 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. ; RB is funded as a postdoctoral researcher by the Research Foundation -Flanders (FWO). SC, CB, NH, PB and HG are members of the Respiratory Syncytial Virus Consortium in Europe (RESCUE). RESCUE has received funding from the Innovative Medicines Initiative 2 Joint Undertaking under grant agreement no. 116019. NH acknowledges support from the University of Antwerp scientific chair in Evidence-Based Vaccinology, financed in 2009-2020 by a gift from Pfizer and in 2016-2019 from GSK. The GRACE project was funded by the European Community's Sixth Framework Programme (grant agreement 518226). Work in the UK was also supported by the National Institute for Health Research. Work in Barcelona was also supported by 2009 SGR 911 Ciber de Enfermedades Respiratorias (Ciberes CB06/06/0028). Work in Belgium was also supported by the Methusalem financing programme of the Flemish Government and by FWO (G.0274.08N). This work was also supported through the European Science Foundation (ESF), in the framework of the Research Networking Programme TRACE (www.esf.org/trace). ; Bruyndonckx, R (corresponding author), Hasselt Univ, DSI, Martelarenlaan 42, B-3500 Hasselt, Belgium. robin.bruyndonckx@uhasselt.be

Objectives: In order to improve antimicrobial (AM) use, a policy of providing technical and financial support to AM management teams (AMTs) was rolled out in all Belgian hospitals between 2002 and 2008. We aimed to analyse the association of this policy with AM use for the two indications accounting for the largest number of patients receiving AM: prophylaxis for major lower limb orthopaedic surgery and pneumonia. Design, setting, participants: We used patient-level data routinely collected in all Belgian acute care hospitals between 1999 and 2010. We modelled trends for selected quality indicators (QIs) using the year of AMT implementation in each hospital as the main 'change point', with fine-tuned case-mix adjustment. Of all admissions for lower limb orthopaedic surgery, and pneumonia between 1999 and 2010, 90% (325 094) and 95% (327 635), respectively, were found eligible for analyses. Outcomes: The surgery QI was defined as: cefazolin, dose in the expected range, and no use of other AM. For pneumonia, QIs were: ratio of oral/parenteral defined daily doses (DDD, O/P QI), and mean number of DDD minus penicillin, per 100 days of hospitalisation (DDD QI). Results: Between 1999 and 2010, the surgery QI improved from 59% to 71%, the O/P QI from 0.72 to 0.97, and the DDD QI from 96 to 64. Heterogeneity between hospitals was high. Overall, no association was found with the year of implementation of the AMT. Conclusions: Improvements have been observed but could not be related at the national level to the policy under study. However, these results cannot be extrapolated to other QIs for AM use in hospitals. Our findings do not question the need for AMT, nor the need for continuation of AMT funding. Several recommendations can be made in order to make the best of Belgium's unique political and financial commitments in that field. ; This study was funded by the Scientific Institute of Public Health (internal grant, 99 429 Euros, project number W3035.0116.1). Data have been generated as part of the routine work of the Ministry of Health and National Sick Fund. RB acknowledges support from a Methusalem research grant from the Flemish government not specific for this project.

In this paper, we propose a change-point mixed model to assess the change in the trend of outpatient antibiotic use in a Bayesian framework, where the change-points are unknown parameters of the model. Model selection using DIC indicates that the data supports the model with a country-specific change-point. The location of the change-points may be related to points in time where public health strategies aiming at increasing the awareness of the public to a more rational use of antibiotics or targeting to reduce overconsumption of antibiotics were initiated. ; We also gratefully acknowledge support from IAP research Network #P6/03 of the Belgian Government (Belgian Science Policy). The 1997-2005 data collection was funded by a grant from DG SANCO of the European Commission (Grant Agreement 20033211), whereas the 2006-09 data collection was funded by the ECDC (Grant Agreement 2007/001).

Antimicrobial resistance (AMR) is now a global threat. Its emergence rests on antimicrobial overuse in humans and food-producing animals; globalization and suboptimal infection control facilitate its spread. While aggressive measures in some countries have led to the containment of some resistant gram-positive organisms, extensively resistant gram-negative organisms such as carbapenem-resistant enterobacteriaceae and pan-resistant Acinetobacter spp. continue their rapid spread. Please start the sentence as follows: Antimicrobial conservation/stewardship programs have seen some measure of success in reducing antimicrobial overuse in humans, but their reach is limited to acute-care settings in high-income countries. Outside the European Union, there is scant or no oversight of antimicrobial administration to food-producing animals, while evidence mounts that this administration leads directly to resistant human infections. Both horizontal and vertical infection control measures can interrupt transmission among humans, but many of these are costly and essentially limited to high-income countries as well. Novel antimicrobials are urgently needed; in recent decades pharmaceutical companies have largely abandoned antimicrobial discovery and development given their high costs and low yield. Against this backdrop, international and cross-disciplinary collaboration appears to be taking root in earnest, although specific strategies still need defining. Educational programs targeting both antimicrobial prescribers and consumers must be further developed and supported. The general public must continue to be made aware of the current scale of AMR's threat, and must perceive antimicrobials as they are: a non-renewable and endangered resource.

Rapid laboratory diagnosis is critical for treating, managing, and preventing methicillin-resistant Staphylococcus aureus (MRSA) infections. We evaluated and compared the potential for MRSA detection of five chromogenic media, Brilliance MRSA agar (Oxoid), ChromID (bioMerieux), MRSASelect (Bio-Rad), CHROMagar (CHROMagar Microbiology), and BBL-CHROMagar (BD Diagnostics). Media were tested with log serial dilutions (100 to 106 CFU) of pure isolates of MRSA (n = 60), non-MRSA (n = 27), and defined mixtures thereof simulating clinical samples (n = 84). Further evaluations were done on pre-enriched nasal and groin screening swabs (n = 213) from 165 hospitalized patients. Randomized samples were spiral plated on each medium and independently scored by five investigators for characteristic colonies at 24 and 48 h of incubation. Confirmatory testing of up to five putative MRSA colonies recovered from each medium was done. The cumulative average sensitivity with isolates, mixtures, and clinical samples was the highest for Brilliance MRSA agar (97%) and similar for the other four media (>= 92%). The cumulative average specificity was the highest for BBL-CHROMagar (99%), followed by MRSASelect (98%), CHROMagar (97%), ChromID (89%), and Brilliance MRSA agar (86%). All of the media detected MRSA at 10 and 1 CFU, although at these low loads, few MRSA samples harboring SCCmec type III or IV were misinterpreted as non-MRSA by investigators. False-positive results were mainly due to methicillin-resistant S. epidermidis. For an arbitrary MRSA prevalence of 5% and based on patient sample evaluations, the positive predictive values for BBL-CHROMagar and CHROMagar (similar to 84%) were the highest. The negative predictive values of all of the media were >= 92% for MRSA prevalences ranging from 5% to 30%. In conclusion, BBL-CHROMagar and CHROMagar gave the best overall results for detection of MRSA, irrespective of the sample concentration, investigator, or incubation period. ; This work and W. S. are supported by funding from the European Community (MOSAR network contract LSHP-CT-2007-037941). S. M.-K. is funded by the Research Foundation Flanders (FWO-V), Belgium. G. M., M. A., and J. C. A. gratefully acknowledge support from FWO-V, research grant G. 0151.05, and Belgian IUAP/PAI network P6/03, Statistical Techniques and Modelling for Complex Substantive Questions with Complex Data, of the Belgian Government (Belgian Science Policy).

While multiple rodent preclinical studies, and to a lesser extent human clinical trials, claim the feasibility, safety, and potential clinical benefit of cell grafting in the central nervous system (CNS), currently only little convincing knowledge exists regarding the actual fate of the grafted cells and their effect on the surrounding environment (or vice versa). Our preceding studies already indicated that only a minor fraction of the initially grafted cell population survives the grafting process, while the surviving cell population becomes invaded by highly activated microglia/macrophages and surrounded by reactive astrogliosis. In the current study, we further elaborate on early cellular and inflammatory events following syngeneic grafting of eGFP(+) mouse embryonic fibroblasts (mEFs) in the CNS of immunocompetent mice. Based on obtained quantitative histological data, we here propose a detailed mathematically derived working model that sequentially comprises hypoxia-induced apoptosis of grafted mEFs, neutrophil invasion, neoangiogenesis, microglia/macrophage recruitment, astrogliosis, and eventually survival of a limited number of grafted mEFs. Simultaneously, we observed that the cellular events following mEF grafting activates the subventricular zone neural stem and progenitor cell compartment. This proposed model therefore further contributes to our understanding of cell graft-induced cellular responses and will eventually allow for successful manipulation of this intervention. ; This work was supported by research grants G.0136.11 and G.0130.11 (granted to Zwi Berneman, Annemie Van der Linden, and Peter Ponsaerts) of the Fund for Scientific Research-Flanders (FWO-Vlaanderen, Belgium), in part by a Methusalem research grant from the Flemish government (granted to Zwi Berneman and Herman Goossens) and in part by funding received from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement No. 278850 (INMiND; granted to Annemie Van der Linden). Debbie Le Blon holds a Ph.D.-studentship from the Flemish Institute for Science and Technology (IWT-Vlaanderen). Chloe Hoornaert holds a Ph.D.-studentship from the FWO-Vlaanderen. The authors declare no conflict of interest.

Despite long-standing two-dose measles-mumpsrubella (MMR) vaccination, measles outbreaks still occur in highly vaccinated European populations. For instance, large measles outbreaks occurred in France (2008–13), the United Kingdom (2012–13) and the Netherlands (2012). Based on a multicohort model approach, using spatial serological survey data, MMR vaccination coverage data and data on social contacts, we found effective reproduction numbers significantly higher than 1 for measles in Belgium. This indicates that at one of the expected re-introductions, a measles outbreak is likely to spread, especially when it occurs during school term. The predicted average effective reproduction number increased over a 30-year time span from 1.3 to 2.2 and from 1.9 to 3.2 for basic reproduction numbers of 12 and 18, respectively. The expected relative measles incidence was highest in infants under one year of age, in adolescents and young adults. In conclusion, gradually increasing proportions of susceptible adolescents and young adults provide through their highly active social life an avenue for measles to resurge in large outbreaks upon re-introduction in Belgium, especially during school terms. Infants form an important vulnerable group during future measles outbreaks. ; The authors would like to acknowledge the colleagues of the Flemish Agency for Care and Health, the Scientific Institute of Public Health and the measles elimination committee for fruitful discussions related to this research. NH acknowledges support of the University of Antwerp Scientific Chair in Evidence-based Vaccinology sponsored in 2009-2014 by a gift from Pfizer. SA acknowledges support by the Research Fund of Hasselt University (Grant BOF11NI31). ES and HG acknowledge support from a Methusalem research grant from the Flemish government. NG is beneficiary of a postdoctoral grant from the AXA Research Fund. Support from the IAP Research Network P7/06 of the Belgian State (Belgian Science Policy) is gratefully acknowledged. HT and EL are postdoctoral researchers for the Fund of Scientific Research - Flanders (FWO). The computational resources and services used in this work were provided by the Hercules Foundation and the Flemish Government - department EWI.

Although intracerebral transplantation of various fibroblast(-like) cell populations has been shown feasible, little is known about the actual in vivo remodeling of these cellular grafts and their environment. In this study, we aimed to compare the in vitro and in vivo behavior of two phenotypically similar but developmentally distinct fibroblast-like cell populations, namely, mouse embryonic fibroblasts (mEFs) and mouse fetal membrane-derived stromal cells (mFMSCs). While both mEFs and mFMSCs are readily able to reduce TNF-alpha secretion by LPS/IFN-gamma-activated BV-2 microglia, mFMSCs and mEFs display strikingly opposite behavior with regard to VEGF production under normal and inflammatory conditions. Whereas mFMSCs downregulate VEGF production upon coculture with LPS/IFN-gamma-activated BV-2 microglia, mEFs upregulate VEGF production in the presence of LPS/IFN-gamma-activated BV-2 microglia. Subsequently, in vivo grafting of mFMSCs and IDEFs revealed no difference in microglial and astroglial responses toward the cellular grafts. However, mFMSC grafts displayed a lower degree of neoangiogenesis compared to mEF grafts, thereby potentially explaining the lower cell number able to survive in mFMSC grafts. In summary, our results suggest that physiological differences between fibroblast-like cell populations might lie at the basis of variations in histopathological and/or clinical outcome following cell grafting in mouse brain. ; This work was supported by research grants G.0136.11 and G.0130.11 (granted to Z.B. and P.P.) of the Fund for Scientific Research-Flanders (FWO-Vlaanderen, Belgium) and in part by a Methusalem research grant from the Flemish government (granted to Z.B. and H.G.). Nathalie De Vocht and Chloe Hoornaert hold a Ph.D.-studentship from the FWO-Vlaanderen. Debbie Le Blon holds a Ph.D.-studentship from the Flemish Institute for Science and Technology (IWT). The authors declare no conflicts of interest.

Background: The international Innovative Medicines Initiative (IMI) project DRIVE-AB (Driving Reinvestment in Research and Development and Responsible Antibiotic Use) aims to develop a global definition of 'responsible' antibiotic use. Objectives: To identify consensually validated quantity metrics for antibiotic use in the outpatient setting. Methods: First, outpatient quantity metrics (OQMs) were identified by a systematic search of literature and web sites published until 12 December 2014. Identified OQMs were evaluated by a multidisciplinary, international stakeholder panel using a RAND-modified Delphi procedure. Two online questionnaires and a face-to-face meeting between them were conducted to assess OQM relevance for measuring the quantity of antibiotic use on a nine-point Likert scale, to add comments or to propose new metrics. Results: A total of 597 articles were screened, 177 studies met criteria for full-text screening and 138 were finally included. Twenty different OQMs were identified and appraised by 23 stakeholders. During the first survey, 14 OQMs were excluded and 6 qualified for discussion. During the face-to-face meeting, 10 stakeholders retained five OQMs and suggestions were made considering context and combination of metrics. The final set of metrics included defined daily doses, treatments/courses and prescriptions per defined population, treatments/courses and prescriptions per defined number of physician contacts and seasonal variation of total antibiotic use. Conclusions: A small set of consensually validated metrics to assess the quantity of antibiotic use in the outpatient setting was obtained, enabling (inter) national comparisons. The OQMs will help build a global conceptual framework for responsible antibiotic use. ; This work was supported by the Innovative Medicines Initiative (IMI) Joint Undertaking (grant agreement no. 115618-Driving re-investment in R&D and responsible antibiotic use-DRIVE-AB. Resources are composed of financial contribution from the European Union's Seventh Framework Programme (FP7/2007-2013) and European Federation of Pharmaceutical Industries and Associations (EFPIA) in-kind contribution.

The establishment and validation of reliable induced pluripotent stem cell (iPSC)-derived in vitro models to study microglia and monocyte/macrophage immune function holds great potential for fundamental and translational neuro-immunology research. In this study, we first demonstrate that ramified CX(3)CR1(+) iPSC-microglia (cultured within a neural environment) and round-shaped CX(3)CR1(-) iPSC-macrophages can easily be differentiated from newly established murine CX(3)CR1(eGFP/+)CCR2(RFP/+) iPSC lines. Furthermore, we show that obtained murine iPSC-microglia and iPSC-macrophages are distinct cell populations, even though iPSC-macrophages may upregulate CX(3)CR1 expression when cultured within a neural environment. Next, we characterized the phenotypical and functional properties of murine iPSC-microglia and iPSC-macrophages following classical and alternative immune polarisation. While iPSC-macrophages could easily be triggered to adopt a classically-activated or alternatively-activated phenotype following, respectively, lipopolysaccharide + interferon gamma or interleukin 13 (IL13) stimulation, iPSC-microglia and iPSC-macrophages cultured within a neural environment displayed a more moderate activation profile as characterised by the absence of MHCII expression upon classical immune polarisation and the absence of Ym1 expression upon alternative immune polarisation. Finally, extending our preceding in vivo studies, this striking phenotypical divergence was also observed for resident microglia and infiltrating monocytes within highly inflammatory cortical lesions in CX(3)CR1(eGFP/+)CCR2(RFP/+) mice subjected to middle cerebral arterial occlusion (MCAO) stroke and following IL13-mediated therapeutic intervention thereon. In conclusion, our study demonstrates that the applied murine iPSC-microglia and iPSC-macrophage culture models are able to recapitulate in vivo microglia and monocyte/macrophage ontogeny and corresponding phenotypical/functional properties upon classical and alternative immune polarisation, and therefore represent a valuable in vitro platform to further study and modulate microglia and (infiltrating) monocyte immune responses under neuro-inflammatory conditions within a neural environment. ; This work was supported by research grant G091518N (granted to PP) of the Fund for Scientific Research-Flanders (FWO-Vlaanderen, Belgium), by a Methusalem research grant from the Flemish government (granted to HG and ZB), by funding received from the Belgian Charcot Foundation (granted to PP and DLB) and by the ASCID (Antwerp Study Centre for Infectious Diseases). AQ and EL are holders of a PhD studentship from the FWO-Vlaanderen. EVB is holder of a PhD studentship from the University of Antwerp. DLB is holder of a postdoctoral fellowship from the FWO-Vlaanderen. FM is supported by the Penis 2016 from the Health Department of Generalitat de Catalunya. Research in the Pasque lab is supported by the Research Foundation - Flanders (FWO) (Odysseus Return Grant G0F7716N, to V.P.), the KU Leuven Research Fund (BOFZAP starting grant StG/15/021BF to V.P. Cl grant C14/16/077 to V.P. and Project financing).

The establishment and validation of reliable induced pluripotent stem cell (iPSC)-derived in vitro models to study microglia and monocyte/macrophage immune function holds great potential for fundamental and translational neuro-immunology research. In this study, we first demonstrate that ramified CXCR1 iPSC-microglia (cultured within a neural environment) and round-shaped CXCR1 iPSC-macrophages can easily be differentiated from newly established murine CXCR1CCR2 iPSC lines. Furthermore, we show that obtained murine iPSC-microglia and iPSC-macrophages are distinct cell populations, even though iPSC-macrophages may upregulate CXCR1 expression when cultured within a neural environment. Next, we characterized the phenotypical and functional properties of murine iPSC-microglia and iPSC-macrophages following classical and alternative immune polarisation. While iPSC-macrophages could easily be triggered to adopt a classically-activated or alternatively-activated phenotype following, respectively, lipopolysaccharide + interferon γ or interleukin 13 (IL13) stimulation, iPSC-microglia and iPSC-macrophages cultured within a neural environment displayed a more moderate activation profile as characterised by the absence of MHCII expression upon classical immune polarisation and the absence of Ym1 expression upon alternative immune polarisation. Finally, extending our preceding in vivo studies, this striking phenotypical divergence was also observed for resident microglia and infiltrating monocytes within highly inflammatory cortical lesions in CXCR1CCR2 mice subjected to middle cerebral arterial occlusion (MCAO) stroke and following IL13-mediated therapeutic intervention thereon. In conclusion, our study demonstrates that the applied murine iPSC-microglia and iPSC-macrophage culture models are able to recapitulate in vivo microglia and monocyte/macrophage ontogeny and corresponding phenotypical/functional properties upon classical and alternative immune polarisation, and therefore represent a valuable in vitro platform to further study and modulate microglia and (infiltrating) monocyte immune responses under neuro-inflammatory conditions within a neural environment. ; This work was supported by research grant G091518N (granted to PP) of the Fund for Scientific Research-Flanders (FWO-Vlaanderen, Belgium), by a Methusalem research grant from the Flemish government (granted to HG and ZB), by funding received from the Belgian Charcot Foundation (granted to PP and DLB) and by the ASCID (Antwerp Study Centre for Infectious Diseases). AQ and EL are holders of a PhD studentship from the FWO-Vlaanderen. EVB is holder of a PhD studentship from the University of Antwerp. DLB is holder of a postdoctoral fellowship from the FWO-Vlaanderen. FM is supported by the Peris 2016 from the Health Department of Generalitat de Catalunya. Research in the Pasque lab is supported by the Research Foundation – Flanders (FWO) (Odysseus Return Grant G0F7716N, to V.P.), the KU Leuven Research Fund (BOFZAP starting grant StG/15/021BF to V.P. C1 grant C14/16/077 to V.P. and Project financing).

[Introduction] The rapid worldwide spread of carbapenem-resistant Enterobacteriaceae (CRE) constitutes a major challenge. The aim of the EUropean prospective cohort study on Enterobacteriaceae showing REsistance to CArbapenems (EURECA), which is part of the Innovative Medicines Initiative Joint Undertaking (IMI JU) funded COMBACTE-CARE project, is to investigate risk factors for and outcome determinants of CRE infections to inform randomised clinical trial designs and to provide a historical cohort that could eventually be used for future comparisons with new drugs targeting CRE. ; [Methods] A multicentre (50 sites), multinational (11 European countries), analytical observational project was designed, comprising 3 studies. The aims of study 1 (a prospective cohort study) include characterising the features, clinical management and outcomes of hospitalised patients with intra-abdominal infection, pneumonia, complicated urinary tract infections and bloodstream infections caused by CRE (202 patients in each group). The main outcomes will be 30-day all-cause mortality and clinical response. Study 2 (a nested case–control study) will identify the risk factors for target infections caused by CRE; 248 selected patients from study 1 will be matched with patients with carbapenem-susceptible Enterobacteriaceae (1:1) and with hospitalised patients (1:3) and will provide a historical cohort of patients with CRE infections. Study 3 (a matched cohort study) will follow patients in study 2 in order to assess mortality, length of stay and hospital costs associated with CRE. All patients will be followed for 30 days. Different, up-to-date statistical methods will be applied to come to unbiased estimates for all 3 studies. ; [Ethics and dissemination] Before-study sites will be initiated, approval will be sought from appropriate regulatory agencies and local Ethics Committees of Research or Institutional Review Boards (IRBs) to conduct the study in accordance with regulatory requirements. This is an observational study and therefore no intervention in the diagnosis, management or treatment of the patients will be required on behalf of the investigation. Any formal presentation or publication of data collected from this study will be considered as a joint publication by the participating physician(s) and will follow the recommendations of the International Committee of Medical Journal Editors (ICMJE) for authorship. ; [Trial registration number] NCT02709408. ; The EURECA project is funded by the Innovative Medicine Initiative (IMI), European Union's Seventh Framework Programme (FP7/2007–2013) and EFPIA companies' in-kind contribution (COMBACTE-CARE, grant agreement 115 620). JR-B and AP received funding for research from the Spanish Network for Research in Infectious Diseases (REIPI RD12/0015 and RD16/2016), Instituto de Salud Carlos III, MInisterio de Economía y Competitivad, co-financed by the European Development Regional Fund 'A Way to Achieve Europe' ERDF; BG-G is the recipient of a Río Hortega grant from Instituto de Salud Carlos III (CM 15/00265). ; Peer reviewed

Detrimental inflammatory responses in the central nervous system are a hallmark of various brain injuries and diseases. With this study we provide evidence that lentiviral vector-mediated expression of the immune-modulating cytokine interleukin 13 (IL-13) induces an alternative activation program in both microglia and macrophages conferring protection against severe oligodendrocyte loss and demyelination in the cuprizone mouse model for multiple sclerosis (MS). First, IL-13 mediated modulation of cuprizone induced lesions was monitored using T-2-weighted magnetic resonance imaging and magnetization transfer imaging, and further correlated with quantitative histological analyses for inflammatory cell influx, oligodendrocyte death, and demyelination. Second, following IL-13 immune gene therapy in cuprizone-treated eGFP(+) bone marrow chimeric mice, we provide evidence that IL-13 directs the polarization of both brain-resident microglia and infiltrating macrophages towards an alternatively activated phenotype, thereby promoting the conversion of a pro-inflammatory environment toward an anti-inflammatory environment, as further evidenced by gene expression analyses. Finally, we show that IL-13 immune gene therapy is also able to limit lesion severity in a pre-existing inflammatory environment. In conclusion, these results highlight the potential of IL-13 to modulate microglia/macrophage responses and to improve disease outcome in a mouse model for MS. ; This work was supported by research grants G.0136.11 (granted to PP, AVDL and ZB), G.0130.11 (granted to PP, AVDL and ZB) and G.0834.11 (granted to PP and SH) of the Fund for Scientific Research-Flanders (FWO-Vlaanderen, Belgium), in part by a Methusalem research grant from the Flemish government (granted to HG), in part by funding received from the European Union's Seventh Framework Programme (FP7/2007-2013) under grant agreement 278850 (INMiND) (granted to AVdL and AMP), in part by the Brainpath project (MSCA IAPP project granted to AVdL) and in part by funding received from the Belgian Charcot Foundation (granted to PP and AVdL). DLB, DS and CG hold a PhD-studentship from the Flemish Institute for Science and Technology (IWT-Vlaanderen). NDV and CH hold a PhD-studentship from the FWO-Vlaanderen. FK and JP hold a post-doctoral fellowship from the FWO-Vlaanderen.

Transplantation of mesenchymal stem cells (MSCs) into injured or diseased tissuefor the in situ delivery of a wide variety of MSC-secreted therapeutic proteinsis an emerging approach for the modulation of the clinical course of several diseases and traumata. From an emergency point-of-view, allogeneic MSCs have numerous advantages over patient-specific autologous MSCs since off-the-shelf cell preparations could be readily available for instant therapeutic intervention following acute injury. Although we confirmed the in vitro immunomodulatory capacity of allogeneic MSCs on antigen-presenting cells with standard coculture experiments, allogeneic MSC grafts were irrevocably rejected by the host's immune system upon either intramuscular or intracerebral transplantation. In an attempt to modulate MSC allograft rejection in vivo, we transduced MSCs with an interleukin-13 (IL13)-expressing lentiviral vector. Our data clearly indicate that prolonged survival of IL13-expressing allogeneic MSC grafts in muscle tissue coincided with the induction of an alternatively activated macrophage phenotype in vivo and a reduced number of alloantigen-reactive IFN- and/or IL2-producing CD8(+) T cells compared to nonmodified allografts. Similarly, intracerebral IL13-expressing MSC allografts also exhibited prolonged survival and induction of an alternatively activated macrophage phenotype, although a peripheral T cell component was absent. In summary, this study demonstrates that both innate and adaptive immune responses are effectively modulated in vivo by locally secreted IL13, ultimately resulting in prolonged MSC allograft survival in both muscle and brain tissue. ; We thank A. Liston and S. Humblet-Baron (VIB Translational Immunology Lab, KU Leuven, Belgium) for sharing their optimized staining protocols for intracellular cytokine analysis by flow cytometry. This work was supported by research grants G.0130.11 and G.0136.11 (granted to A.V.d.L., Z.N.B. and P.P.), G.0131.11 (granted to Z.N.B. and P.P.), G.0834.11 (granted to S.H. and P.P.) and G.0851.11 (granted to C.V. and Z.N.B.) of the Research Foundation Flanders (FWO Vlaanderen, Belgium) and in part by a Methusalem research grant from the Flemish government (granted to H.G.). C.J.H. and E.Lu. hold a PhD studentship from the FWO Vlaanderen. C.G. and D.L.B. hold a PhD studentship from the Flemish Institute for Science and Technology (IWT Vlaanderen).