Background/Purpose:

We have shown that therapeutic response in juvenile idiopathic arthritis (JIA) is a non-linear process invloving reorganization of gene expression networks. However, our earlier studies were performed on whole blood and neutrophils. Detailed descriptions of the lymphoid compartment have not been published.  We undertook this study to gain a better understanding of treatment response in JIA using transcriptome analysis of peripheral blood CD4+ T cells.

Methods:

This was a cross-sectional study of children with polyarticular, RF-negative JIA, who ranged in age from 5-13 years.  Subjects included 12 patients with active disease on therapy with methotrexate (MTX) and etanercept (ADT), 10 patients also on MTX and etanercept who met crieria for clinical remission on medication (CRM),and 10 healthy control children (HC).   CD4+ T cells were obtained from peripheral blood by positive selection and RNA purified and cDNA libraries prepared using conventional appproaches. Libraries were sequenced using 100 base pair (bp) paired-end reads on the Illumina HiSeq 2500 platform. We used standard statistical approaches to identify differentially expressed genes, and gene ontology (GO) analysis to identify common functional properties among groups of differentially expressed genes.   

Results: We identified 4062 genes that were differentially expressed between ADT and HC, 3454 genes that demonstrated expression differences between ADT and CRM, and 22 genes that were expressed differently between HC and CRM. These findings differ from what we have seen in neutrophils, where transcriptional profiles of children who have achieved CRM differ significantly from those of HC.  We next plotted all differentially expressed genes called between any pair of sample groups and used k-means clustering  to group genes into gene clusters.  We identified 5 distinct subgroups, representing different cellular functions. Cluster 1, which was characterized by increased expression in HC and CRM compared to ADT, was involved in metabolic processes. Clusters 2 and 4, representing genes that showed higher expression in the ADT group compared the HC and CRM groups, were enriched for genes involved in transcription and translation, indicating that in the active disease state, CD4+T-cells were more active in their transcriptional and translational processes. Cluster 3, which was characterized by higher expression in HC samples compared to CRM or ADT samples, was enriched for genes involved in immune activation and may represent genes that are suppressed by treatment.  Cluster 5 contained genes that showed a wide variety of expression patterns across the samples but show a general increase in expression in the ADT samples compared to the CRM and HC samples; this cluster was represented by genes involved in RNA processing and RNA metabolism. 

Conclusion:

CD4+ T cells undergo significant re-organization of their transcriptional repertoires over the course of therapy. This re-organization involves fundamental cellular processes such as metabolism and the processing of RNA transcripts.  Further research to determine whether these changes are necessary for or merely associated with therapeutic response is warranted.  

Fig1-2

« Back to 2019 ACR/ARP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/transcriptomic-responses-in-cd4-t-cells-during-successful-therapy-for-juvenile-idiopathic-arthritis/