Background Genomic medicine has paved the way for identifying biomarkers and therapeutically actionable targets for complex diseases, but is complicated by the involvement of thousands of variably expressed genes across multiple cell types. Single-cell RNA-sequencing study (scRNA-seq) allows the characterization of such complex changes in whole organs. Methods The study is based on applying network tools to organize and analyze scRNA-seq data from a mouse model of arthritis and human rheumatoid arthritis, in order to find diagnostic biomarkers and therapeutic targets. Diagnostic validation studies were performed using expression profiling data and potential protein biomarkers from prospective clinical studies of 13 diseases. A candidate drug was examined by a treatment study of a mouse model of arthritis, using phenotypic, immunohistochemical, and cellular analyses as read-outs. Results We performed the first systematic analysis of pathways, potential biomarkers, and drug targets in scRNA-seq data from a complex disease, starting with inflamed joints and lymph nodes from a mouse model of arthritis. We found the involvement of hundreds of pathways, biomarkers, and drug targets that differed greatly between cell types. Analyses of scRNA-seq and GWAS data from human rheumatoid arthritis (RA) supported a similar dispersion of pathogenic mechanisms in different cell types. Thus, systems-level approaches to prioritize biomarkers and drugs are needed. Here, we present a prioritization strategy that is based on constructing network models of disease-associated cell types and interactions using scRNA-seq data from our mouse model of arthritis, as well as human RA, which we term multicellular disease models (MCDMs). We find that the network centrality of MCDM cell types correlates with the enrichment of genes harboring genetic variants associated with RA and thus could potentially be used to prioritize cell types and genes for diagnostics and therapeutics. We validated this hypothesis in a large-scale study of patients with 13 different autoimmune, allergic, infectious, malignant, endocrine, metabolic, and cardiovascular diseases, as well as a therapeutic study of the mouse arthritis model. Conclusions Overall, our results support that our strategy has the potential to help prioritize diagnostic and therapeutic targets in human disease. Electronic supplementary material The online version of this article (10.1186/s13073-019-0657-3) contains supplementary material, which is available to authorized users.

SHS is a valid, reliable and responsive HRQoL instrument also in patients with CD. It is easily completed by the patient and requires no further calculation by the investigator. SHS gives a comprehensive overview of the main aspects of the patient's subjective health perception and is a useful tool in both clinical practice and clinical studies.

The Swedish version of RFIPC exhibited an adequate psychometric performance in CD patients, but was less sensitive to change in disease activity. The patients were more concerned about complications and achievement than intimacy and stigmatization. The strongest predictors of more worry were active disease, female gender and higher BMI.

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This study characterized the burden of CD in a large population-based cohort. CD had higher impact on HRQL, compared with UC. Women with CD had worse outcome in subjective health status, but not in objective assessment of disease activity. Women also had higher rates of sickness, disability pension and single living. The mechanism underlying the sex-related inequalities in outcome for CD warrants further elucidation.