title: Elevated levels of serum MRP8/14 in ankylosing spondylitis: associated with peripheral arthritis and active disease.
abstract: Monocytes of patients with ankylosing spondylitis (AS) have toll-like receptor 4 (TLR4) overexpression on their monocytes. Myeloid-related protein (MRP) 8/14 protein complexes are calcium-binding proteins, which act as endogenous ligands to TLR4. Thus, we studied the levels of MRP8/14 in adult AS patients. MRP8/14 levels were assessed in 99 adult AS patients satisfying Assessments in Ankylosing Spondylitis International Society 2010 criteria and 71 healthy controls by ELISA. Patient disease parameters like patient and physician global assessment, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), swollen and tender joint count, entheseal count by Maastricht enthesitis index, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) were also recorded. Levels were reassessed in 23 patients after 2-5 months of treatment with NSAIDs. All values are in median (IQR). The serum MRP8/14 levels in patients [34.1 (17.94-264.58) μg/ml] were significantly higher than in healthy controls [4.94 (IQR 3.01-8.32) μg/ml (p < 0.0001)]. Patients with peripheral arthritis (n = 50) had higher levels than those with pure axial disease (n = 49) [40.63 (IQR 28.41-73.15) μg/ml vs. 23.72 (11.04-61.55) μg/ml; p = 0.012]. Levels of MRP8/14 correlated with AS Disease Activity Score (DAS)-CRP (r = 0.23, 95%CI = 0.038-0.422, p = 0.02) and CRP (r = 0.28, 95%CI = 0.081-0.45, p = 0.01), and the correlation was better in early disease [≤5 years disease duration; r = 0.40, p = 0.007 and r = 0.57, p = <0.0001, respectively]. Baseline levels were higher in treatment responders than in non-responders [51.17 vs. 32.22 μg/ml; p = 0.02]. Change in MRP8/14 levels correlated with change in BASDAI and ASDAS-CRP (r = 0.489, p = 0.018 and r = 0·498, p = 0.016, respectively). MRP8/14 levels may be used as a biomarker for activity, peripheral arthritis, and response to therapy.
authors.affiliation: Department of Clinical Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, India.
authors.forename: Latika
authors.initials: L
authors.lastname: Gupta
authors.affiliation: Department of Clinical Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, India.
authors.forename: Shruti
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Department of Clinical Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Agarwal
authors.affiliation: Department of Clinical Immunology, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, 226014, India. amita@sgpgi.ac.in.
authors.forename: Amita
authors.initials: A
authors.lastname: Aggarwal
mesh_terms: D000293:Adolescent; D000328:Adult; D001168:Arthritis / Q000097:blood* / Q000150:complications; D015415:Biomarkers / Q000097:blood; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000737:chemistry; D040501:Calgranulin A / Q000097:blood*; D040502:Calgranulin B / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007113:Immunity, Innate; D007249:Inflammation; D008297:Male; D008875:Middle Aged; D025242:Spondylarthropathies / Q000097:blood; D013167:Spondylitis, Ankylosing / Q000097:blood* / Q000150:complications; D055815:Young Adult
chemical_list: D015415:Biomarkers; D040501:Calgranulin A; D040502:Calgranulin B; D002097:C-Reactive Protein
keywords: Endogenous ligands; Innate immunity; Spondyloarthropathy; TLR4