BackgroundAdvances in immunotherapy by blocking TNF have remarkably improved treatment outcomes for rheumatoid arthritis (RA) patients. Although treatment specifically targets TNF-α, the downstream mechanisms of immune suppression are not completely understood, and the reason for the reduced efficacy in a significant fraction of patients remains unclear. Hence this study was designed to detect biomarkers and expression signatures of response to TNF inhibition.MethodsIn this study, we included 39 female patients diagnosed with RA who were non-responders to methotrexate treatment. The blood samples were collected before anti-TNF treatment initiation, and three months into treatment. The clinical evaluations were performed based on European League Against Rheumatism (EULAR) and classified 23 patients as responders and 16 as non-responders after three months following the initiation of anti-TNF treatment. We investigated differences in gene expression in peripheral blood mononuclear cells (PBMCs), the proportion of cell types and cell phenotypes in peripheral blood using flow cytometry, the level of proteins in serum, as well as clinical and demographic factors.ResultsWe performed analyses to identify differences between responders and non-responders at both time points (before and after treatment initiation) as well as to detect the changes induced during the treatment using transcriptomics, flow cytometry and proteomics data. The gene expression analysis before treatment revealed notably a higher expression of EPPK1 and BCL6-AS1 in future responders. We further detected suppression of genes and proteins during treatment, most notably a suppression of expression of the gene, T-cell inhibitor CHI3L1 and its protein YKL-40 measured from flow cytometry. We identified an increase in the proportion of T- and B cells, whereas the proportion of granulocytes was suppressed during treatment in responders. Finally, our machine learning models mainly based on transcriptomics data showed high predictive utility (ROC AUC ± SEM: 0.81 ± 0.17) in classifying response before anti-TNF treatment initiation.ConclusionsOur comprehensive analyses resulted in several useful insights regarding the transcriptional and translational regulations of anti-TNF treatment in RA patients. The study reports first transcriptomics analysis using RNA sequencing of isolated PBMCs from anti-TNF naïve and anti-TNF treated RA patients to study biomarkers and predict anti-TNF response.