Trace Element Deficiency in Axial Spondyloarthritis and Psoriatic Arthritis in Relation to Markers of Inflammation and Remission.

Selenium (Se) is an essential micronutrient for antioxidant defense. Selenoproteins are involved in metabolic and signaling pathways of autoimmune and autoinflammatory diseases. Copper (Cu) and zinc (Zn) are integral components of key enzymes and regulatory proteins. Trace element (TE) dysregulations have potential relevance as disease biomarkers. In this study, we compare TE status and TE profiles between patients with axial spondyloarthritis (axSpA) and psoriatic arthritis (PsA), and relate the results to markers of inflammation, remission, and healthy controls. Serum TE was measured using total reflection X-ray fluorescence. The Se transporter SELENOP and extracellular glutathione peroxidase (GPx3) were determined by ELISA and enzymatic assay, respectively. Both groups of patients (axSpA; n = 84, and PsA; n = 76) displayed TE deficiency compared to healthy European adults. Serum Cu, Se, Zn, SELENOP, and GPx3 levels were not different between the groups. The serum Cu and Cu-Zn ratio correlated positively with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). An inverse correlation of serum Se, Zn, and SELENOP with CRP was observed in axSpA, but not in PsA. On average, all TE, including the inflammation-responsive Cu levels, were below reference ranges, indicating a TE deficiency in both groups. Increasing CRP was associated with low SELENOP levels, suggesting personalized Se substitution as indicated to maintain systemic Se supply and protect from ferroptotic cell loss under inflammatory conditions.