CANDY has completed its first Periodic Report and its has been approved by our EIC-Project Office. Please find here the publishable summary of the first 18 months of our exciting project.
Summary of the context and overall objectives
Between 50 to 75 million children and adults in Europe suffer from early onset neurodevelopmental disorders. These disorders include autism, attention-deficit hyperactivity disorder, Intellectual Disability and language disorders, and pose an enormous burden for patients and their families, and for society as a whole. This burden is due to the high prevalence, the overlap of these disorders with each other, and the frequent combination with somatic diseases such as epilepsy, allergies, immune and gastrointestinal diseases, and visual and auditory handicaps. Patients with these disorders die on average 20 years earlier than individuals in the general population.
State-of-the-art clinical care is able to manage clinical symptoms, prevent further complications and improve outcome in some patients. The main problem however is that there are no curative treatments for these disorders, and that our understanding of the underpinning pathophysiology is still only fragmentary.
The overall goal of CANDY is to improve the understanding of the crosstalk between genetics, the immune system, and the bacteria in the gut (microbiome), and thereby provide a compelling novel conceptual framework to understand the pathophysiology of neurodevelopmental disorders. The more specific aims are 1) Elucidate the causal mechanisms that underlie these disorders and the combination with somatic disease, 2) Deliver novel biomarkers to guide early diagnosis and prevention, stratification and/or treatment monitoring, 3) Propose and lay the groundwork for new strategies for prevention and treatment of neurodevelopmental disorders,and epilepsy, and 4) Open-up new avenues for research.
Work performed within the first 18 month
In workpackage 1 we have performed assessments of sensory processing and behavioural phenotypes and EEG assessments in the NRXN1 and SHANK3 genetic mouse models at various development stages, and performed behavioural profiling of PTCHD1 knock-out mice. We collected tissue samples and blood from early postnatal and late developmental stages for further immune profiling. We found that the NRXN1 and SHANK3 models reveal different trajectories of sensory information processing deficits, which provides a basis to establish readouts for pathogenic pathways. The PTCHD1 knock-out model showed altered behaviour but normal sterol levels in the brain as well as in blood samples.
In workpackage 2 we have made significant progress in the preparations of the development of the translational test battery for mice, including ethical permission, import of the SHANK3 knockout mice, breeding, protocol development and sample collection for ex vivo analyses of the glutamatergic system and immune signalling. To integrate behavioural and physiological measurements, we have started a market search for the best suitable telemetry system to measure physiology. Given the restrictions on experimental work in humans due to the COVID-19 pandemic, we have created online versions of the preschool and school going task batteries. Psychometric properties of the tests were quite good. The social habituation task that has been implemented represents the first truly translational measure of social reward sensitivity based on a paradigm successfully used in rodents.
In workpackage 3 we have prepared, finalized and sent the SOPs for the management of the biological material (blood, feces). Serum samples from the two-hit mouse model and the PTCHD1-KO mouse model have evaluated for the following immune factors: INFγ, IL-1β, IL-2, IL-4, IL-5, IL-6, KC/GRO, IL12p70, TNFα. We have also started the assessments of the immune markers of the LEAP study.
Concerning workpackage 4 we have extended the existing protocol for the Preschool Imaging Project (PIP) with the measures and participants (with ADHD, ID and epilepsy) for CANDY, and ethics approval has been obtained at each study centre. We also created SOPs for data collection of these measures, and trained researchers on relevant clinical instruments. Magnetic Resonance Spectroscopy (MRS) was added to the standard preschool protocol and pilot data has been successfully acquired at each site. Recruitment and in-person assessment was affected by considerable restrictions and lockdowns due to the COVID-19 pandemic. Nevertheless, recruitment and assessment of ADHD and ID participant has started in each site.
For workpackage 5 we have completed the ethics protocol for the multiplex study and all sites have sent it to their ethical boards. Paris sites already have the ethics approval and recruited 5 MPX families. All additional sites have already identified/preselected multiplex families that meet all inclusion criteria, as a contingency measure. These families will be enrolled in the project as soon as the ethics committees gave their authorizations. The pipelines for variant calling and validation are ready. We made an operative list of genes associated with NDDs, and conducted a large-scale study on more than 13,000 individuals with ASD and 210,000 undiagnosed individuals. We were able to provide a gene-level map of the prevalence of loss of function (LoF) variants affecting 220 genes robustly associated with ASD.
In workpackage 6 we have adapted the AIMS-2-TRIALS database to enable the centralization of CANDY data, for all the domains (behavioral, neuroimaging, genetics, clinical), both raw and processed. It ensures the whole data cycle from data collection to data reuse as described in the FAIR principles.
For workpackage 7 we have formed an Impact and Dissemination Board (IDB) and compiled a Communication and Dissemination Plan, and organized several webinars amongst others one on Open Science, and master classes. A public project website is online and is running smoothly.
Workpackage 8 has developed a Data Management Plan, collected statements from the Data Protection Officers (DPO) of the sites, and set-up an Internet-based discussion forum.
Progress beyond the state of the art, expected results until the end of the project and potential impacts
The intended and expected impact of CANDY is to give new directions for clinical research to improve prevention, diagnosis, prognosis, therapy development, and management of neurodevelopmental disorders and their co- and multimorbidities such as epilepsy. Research in CANDY will lay the ground work for prevention of early maternal immune-activation, for new intervention strategies (immune-modulation/stem-cells, or probiotics, nutrition; and/or identify new druggable targets) for neurodevelopmental disorders. We will identify developmental windows of opportunity for these interventions, and provide clinical recommendations for (early) diagnosis, preventions and treatment of NDDs and their somatic multimorbidities.
Whenever relevant, identified biomarkers can be used for more accurate and earlier diagnosis, prognosis as well as monitoring of patients’ condition. We will deliver and test biomarkers (genetic/immunogenetic, immune-related, microbiome, as well as eye-tracking, neurocognition and neuroimaging) for (early) diagnostic, predictive, mechanistic and stratification purposes, and build prediction models for risk and onset of epilepsy) or gastro-intestinal or (auto)immune diseases in patients with neurodevelopmental disorders from preschool to adult age.
Figure 1: Overview of the experimental procedures for translational test battery for mice
As part of the “Horizon 2020” programme, the European Commission is funding the five-year CANDY research project with a total of six million Euro under grant agreement No. 847818.