Each unique parameterization of the model specifies one ‘virtual NOD mouse’, and each virtual mouse is validated by extensive comparisons of simulated responses against published data (see below). This approach focuses on finding BGJ398 purchase biologically feasible parameterizations that reproduce critical behaviours, rather than on exact characterization of numerous difficult-to-measure parameters. In support

of our approach focusing on behavioural validation and prediction, a recent analysis of 17 other systems biology models, some with more than 200 parameters, suggests that attention to predictive accuracy, rather than parametric precision, is critical and can provide scientific value in areas where biological relationships are characterized incompletely [3]. Other models of type 1 diabetes have provided valuable insight into disease pathogenesis or health care optimization (e.g. [4–9]). As this model was designed to support drug development, it differs from existing models in the following areas. First, our model includes multiple contributors to the pathogenic process in order to support physiologically based representation of a diverse

GSK1120212 cell line set of therapeutic strategies. Second, we model multiple disease stages, tracking autoimmune pathogenesis from initiation through diabetes onset in order to investigate relative efficacy associated with interventions applied at different disease stages. It should be noted that the focus of our model (and most corresponding NOD mouse research) is on disease prevention or remission, not disease management. Finally, our model represents the physiologically based interactions leading to destruction of β cells, differentiating it from Archimedes, another large-scale diabetes model which Wilson disease protein includes detailed representation of metabolic responses, health care and complications, but in which disease results from a mathematical combination of epidemiological factors [8]. This paper is a biology-focused description of the Type 1 Diabetes PhysioLab platform intended

to introduce the model at a level of detail appropriate for understanding its research applications. Due to its size, a full mathematical description of the entire platform is not reasonable within the body of text. However, to illustrate our modelling approach, the equations, assumptions and data sources for a key module, islet CD8+ T lymphocytes, are summarized in Appendix S1, along with textual explanations. Further, the full model is available freely online as a downloadable file, including all equations, parameters, references, documentation, simulated intervention experiments reproducing published protocols and their associated simulation results (Appendix S2). We applied a top-down, outcomes-focused approach in developing the Type 1 Diabetes PhysioLab platform.