Serum lubricin levels in patients with juvenile idiopathic arthritis

Abstract

Objectives: Lubricin, encoded by the proteoglycan 4 (PRG4) gene, is mainly responsible for lubricating joints. However, there is expanding evidence on its involvement in inflammatory pathways. Juvenile idiopathic arthritis (JIA) is a heterogeneous group of chronic arthritides with an unknown origin in children aged below 16 years. It is characterized by chronic joint inflammation, including synovial inflammation, and may result in cartilage destruction. We aimed to determine whether serum lubricin levels are affected in JIA patients. Material and methods: This cross-sectional study included children diagnosed with JIA and 28 healthy controls. The patients were divided into two groups according to the presence of remission at the time of study. Lubricin protein analysis was performed by the enzyme-linked immunosorbent assay method. Serum samples were obtained at the study enrollment, and lubricin levels were measured once, and compared between JIA patients and healthy controls, and between JIA patients with active disease and remission. Results: The study included 52 JIA patients (28 female, 24 male) and 28 healthy controls (18 female, 10 males). The mean age at study enrollment was 11.66 ±4.41 years and 12.72 ±4.52 years in the JIA patient and control groups, respectively. Although median serum lubricin level did not differ between JIA patients (median: 0.66 ng/μl, range: 0.02-3.85 ng/μl) and healthy controls (median: 0.52 ng/μl, range: 0.06-3.84 ng/μl), it was statistically significantly higher in patients with active disease (median: 1.58 ng/μ, range: 0.08-3.85 ng/μl) than both patients in remission (median: 0.57 ng/μl, range: 0.02-3.57 ng/μl) and healthy controls. A low degree positive correlation was also found between serum lubricin levels and erythroid sedimentation rate of the JIA patients (r = 0.383 and p = 0.011). Conclusions: This is the first study investigating serum lubricin levels in JIA patients, and we found elevated serum lubricin levels in JIA patients with active disease. Further studies are needed to clarify our results.

Plasma proteome profiling of healthy subjects undergoing bed rest reveals unloading‐dependent changes linked to muscle atrophy

“…Proteoglycan 4 (PRG4)/lubricin is a cartilage protein whose serum abundance increases in patients with active inflammatory cartilage disease. 29 We detected a minor increase in the plasma abundance of PRG4 during bed rest, but a significant twofold decrease 2 days after reloading. Lumican, a protein enriched in the extracellular matrix of articular cartilage, was more abundant at BR0 than at both BR10 and BR5, as we could Figure 4 Common features of muscle atrophy in bed rest and cancer cachexia.…”

“…It will be of interest to test Teneurin 4 as a readout for NMJ instability. Proteoglycan 4 (PRG4)/lubricin is a cartilage protein whose serum abundance increases in patients with active inflammatory cartilage disease 29 . We detected a minor increase in the plasma abundance of PRG4 during bed rest, but a significant twofold decrease 2 days after reloading.…”

Mass Spectrometry-Compatible Elution Technique Enables an Improved Mucin-Selective Enrichment Strategy to Probe the Mucinome

“…Additionally, SF is relatively invasive to obtain; a serum-based sequencing method could be beneficial to developing diagnostic tools for OA/RA patients. However, while lubricin is present at 5–7 μg/mL in SF, it is much less abundant in the serum (0.5–1.4 μg/mL); thus, enrichment is necessary. , …”

“…However, while lubricin is present at 5−7 μg/mL in SF, it is much less abundant in the serum (0.5−1.4 μg/mL); thus, enrichment is necessary. 23,24 We reasoned that our optimized StcE E447D enrichment procedure could allow for glycoproteomic mapping of lubricin from the human serum. To do so, 2.5 mg of the human serum was reacted with StcE E447D -conjugated beads and eluted with SDC.…”

Optimized mucin-selective enrichment strategy to probe the mucinome

“…However, while lubricin is present at 5-7 µg/mL in SF, it is much less abundant in serum (0.5-1.4 µg/mL), thus enrichment is necessary. 24,25 We reasoned that our optimized StcE E447D enrichment procedure could allow for the glycoproteomic mapping of lubricin from human serum. To do so, 2.5 mg of human serum was reacted with StcE E447D -conjugated beads and eluted with SDC.…”