Objectives
Autoantibody-responses rise years before onset of inflammatory arthritis (IA) and are stable during transitioning from clinically suspect arthralgia (CSA) to IA. Cytokine and chemokine levels also rise years before IA-onset. However, the course in the at-risk stage of CSA during progression to disease or non-progression is unknown. To increase understanding of processes mediating disease development, we studied the course of cytokine, chemokine and related receptors gene expression in CSA-patients during progression to IA, and in CSA-patients who ultimately did not develop IA.
Methods
Whole-blood RNA-expression of 37 inflammatory cytokines/chemokines/related receptors was determined by dual-colour reverse-transcription multiplex ligation-dependent probe amplification, in paired samples of CSA-patients at CSA-onset and either at IA-development or after 24-months without IA-development. ACPA-positive and ACPA-negative CSA-patients developing IA were compared at CSA-onset and during progression to IA. Generalised estimating equations tested changes over time. A false discovery rate approach was applied.
Results
None of the cytokines/chemokine genes significantly changed in expression between CSA-onset and IA-development. In CSA-patients without IA-development, G-CSF expression decreased (p= 0.001), whereas CCR6 and TNIP1 expression increased (p< 0.001, p= 0.002, respectively) over a 2-year period. Expression levels in ACPA-positive and ACPA-negative CSA-patients who developed IA were similar.
Conclusion
Whole-blood gene expression of assessed cytokines/chemokines/related receptors did not change significantly from CSA to IA-development. This suggests that changes in expression of these molecules may not be related to the final process of developing chronicity and may have occurred preceding CSA-onset. Changes in gene expression in CSA-patients without IA-development may provide clues for processes related to resolution.