A Biomedical Knowledge Graph System to Propose Mechanistic Hypotheses for Real-world Environmental Health Observations: Application (Preprint)
BACKGROUND Knowledge graphs are a common form of knowledge representation in biomedicine and many other fields. We developed an open biomedical knowledge graph–based system termed Reasoning Over Biomedical Objects linked in Knowledge Oriented Pathways, or ROBOKOP. ROBOKOP consists of both a front-end user interface and a back-end knowledge graph. The ROBOKOP user interface allows users to posit questions and explore answer subgraphs. Users can also posit questions through direct Cypher query of the underlying knowledge graph, which currently contains roughly 6M nodes or biomedical entities and 140M edges or predicates describing the relationship between nodes, drawn from >30 curated data sources. OBJECTIVE We aimed to apply ROBOKOP to survey data on workplace exposures and immune-medicated diseases from the Environmental Polymorphisms Registry (EPR) within the National Institute of Environmental Health Sciences. METHODS We analyzed EPR survey data focused on immune-mediated diseases and identified 45 associations between chemical workplace exposures and immune-mediated diseases, as self-reported by study participants (N = 4574), with 20 associations significant at P < .05 after a false discovery rate connection. We then used ROBOKOP to: (1) validate the associations by determining whether plausible connections exist within the ROBOKOP knowledge graph; and (2) propose biological mechanisms that might explain them and serve as hypotheses for subsequent testing. We highlight three exemplar associations: carbon monoxide – multiple sclerosis; ammonia – asthma; and isopropanol – allergic disease. RESULTS ROBOKOP successfully returned answer sets for three queries that were posed in the context of the driving examples. The answer sets included potential intermediary genes, as well as supporting evidence that might explain the observed associations. CONCLUSIONS We demonstrate a real-world application of ROBOKOP to generate mechanistic hypotheses for associations between chemical workplace exposure and immune-mediates diseases. We expect that ROBOKOP will find broad application across many biomedical fields and other scientific disciplines due to its generalizability, speed to discovery and generation of mechanistic hypotheses, and open nature.