Serum biomarkers and their relationship to axial spondyloarthritis associated with inflammatory bowel diseases.

Spondyloarthritis (SpA) constitute a group of chronic inflammatory immune-mediated rheumatic diseases characterized by genetic, clinical, and radiological features. Recent efforts have concentrated on identifying biomarkers linked to axial SpA associated with inflammatory bowel disease (IBD), offering predictive insights into disease onset, activity, and progression. Genetically, the significance of the HLA-B27 antigen is notably diminished in ankylosing spondylitis (AS) associated with IBD, but is heightened in concurrent sacroiliitis. Similarly, certain polymorphisms of endoplasmic reticulum aminopeptidase (ERAP-1) appear to be involved. Carriage of variant NOD2/CARD15 polymorphisms has been demonstrated to correlate with the risk of subclinical intestinal inflammation in AS. Biomarkers indicative of pro-inflammatory activity, including C-reactive protein (CRP) along with erythrocyte sedimentation rate (ESR), are among the consistent predictive biomarkers of disease progression. Nevertheless, these markers are not without limitations and exhibit relatively low sensitivity. Other promising markers encompass IL-6, serum calprotectin (s-CLP), serum amyloid (SAA), as well as biomarkers regulating bone formation such as metalloproteinase-3 (MMP-3) and Dickkopf-related protein 1 (DKK-1). Additional candidate indicators of structural changes in SpA patients include matrix metalloproteinase-3 (MMP-3), vascular endothelial growth factor (VEGF), tenascin C (TNC), and CD74 IgG. Fecal caprotein (f-CLP) levels over long-term follow-up of AS patients have demonstrated predictive value in anticipating the development of IBD. Serologic antibodies characteristic of IBD (ASCA, ANCA) have also been compared; however, results exhibit variability. In this review, we will focus on biomarkers associated with both axial SpA and idiopathic intestinal inflammation, notably enteropathic spondyloarthritis.

Elevated Tenascin-C Serum Levels in Patients With Axial Spondyloarthritis.

This study aimed to examine serum tenascin C (TNC) in different subsets of axial spondyloarthritis (axSpA) patients. Sixty-one patients fulfilling the Assessment of SpondyloArthritis international Society classification criteria for axSpA and 20 healthy subjects (HS) were included in study. Based on imaging, patients were classified as non-radiographic (n=16) and radiographic (n=45) axSpA. TNC serum levels were determined by ELISA. Disease-related factors including the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) and C-reactive protein (CRP) levels, were determined. TNC levels were elevated in axSpA patients [535.3 (457.7-677.2) ng/ml] compared to HS [432.1 (329.1-565.9) ng/ml, p=0.007]. Dividing axSpA into radiographic and non-radiographic subsets, the difference in TNC was observed between the radiographic subset and HS [535.3 (434.5-677.2) vs. 432.1 (329.1-565.9) ng/ml, p=0.022]. TNC levels did not correlate with disease activity measures (serum CRP or BASDAI). Nevertheless, the weak correlation of TNC levels with different disease stages (r=0.25, p=0.025) was found, with the highest levels in patients with syndesmophytes. TNC levels are elevated across various subsets of axSpA, and although not related to systemic disease activity, TNC levels might reflect chronic structural spinal changes in axSpA patients. However, its specific role in bone metabolism should be elucidated in further studies.