Soluble Low-density Lipoprotein Receptor-related Protein 1 in Juvenile Idiopathic Arthritis

Objective This study aimed to expand knowledge about soluble low-density lipoprotein receptor-related protein 1(sLRP1) in juvenile idiopathic arthritis (JIA) by determining associations of sLRP1 levels in non-systemic JIA patients with clinical and inflammatory biomarker indicators of disease activity. Methods Plasma sLRP1 and 46 inflammation-related biomarkers were measured at enrollment and six months later in a cohort of 96 newly diagnosed Canadian non-systemic JIA patients. Relationships between sLRP1 levels and indicators of disease activity and biomarker levels were analyzed at both visits. Results At enrollment, sLRP1 levels correlated negatively with age and active joint counts. Children showed significantly higher levels of sLRP1 than adolescents (mean ranks: 60.7 and 47.8, respectively; p=0.032). Participants with four or fewer active joints compared to those with five or more active joints, had significantly higher sLRP1 levels (mean ranks: 60.6, and 44.7, respectively; p=0.007). At enrollment, considering the entire cohort, sLRP1 correlated negatively with the number of active joints (r=-0.235; p=0.017). In the entire cohort, sLRP1 levels at enrollment and six months after correlated with 13 and six pro-and anti-inflammatory biomarkers, respectively. In JIA categories, sLRP1 correlations with inflammatory markers were significant in rheumatoid factor negative polyarticular JIA, oligoarticular JIA, enthesitis related arthritis, and psoriatic arthritis at enrollment. Higher sLRP1 levels at enrollment increased the likelihood of absence of active joints 6 months later. Conclusion Plasma sLRP1 levels correlate with clinical and biomarker indicators of short-term improvement in JIA disease activity supporting sLRP1 as an upstream biomarker of potential utility for assessing JIA disease activity and outcome prediction.