Background. Lumbar disc herniation (LDH) is the most common diagnosed degenerative pathology in the lumbar spine. Because of its role in spinal stability there is an increased interest in the role of the Lumbar Multifidus muscle in low back pain research. Despite surgical treatment long-term, disability and pain remain a persistent problem. The aim of the study is to compare side-to-side Lumbar Multifidus muscle fibre characteristics in unilateral LDH patients, and compare both sides to a healthy control group. Methods. Thirty patients (n = 17 men and n = 13 women) scheduled for microdiscectomy for unilateral disc herniation and ten healthy controls (n = 5 men and n = 5 women) were included in this study. Biopsies of the Lumbar Multifidus muscle were analysed by means of immunohistochemistry combined with immunofluorescence microscopy to determine type I and type II muscle fibre type distribution, cross-sectional area, myonuclear-and satellite cell content, inflammation and various indices of muscle fibre capillarisation. Results. The proportion of muscle fibres with centrally located myonuclei, various indicis of muscle fibre capillarisation and pro-and anti-inflammatory cell content were higher in the patients compared with the healthy controls. No differences were observed in type I and type II muscle fibre characteristics between the injured and uninjured side within the LDH patients. Conclusions. This study shows clear differences in Lumbar Multifidus muscle fibre characteristics between LDH patients, irrespective of injured or uninjured side, and healthy controls. Additional studies are warranted to establish the clinical significance of these differences in muscle fibre morphology in LDH compared with healthy controls. Study registration. This trial was registered on ClinicalTrials.gov under the identification number NCT03753711.

BackgroundThere is an unmet need for biomarkers to identify patients with axial spondyloarthritis (axSpA), as clinical manifestations often overlap with other disorders. Previously, we identified immunoglobulin G (IgG) antibodies to 3 Hasselt University (UH)-axSpA peptides which could provide a novel tool for diagnosis of a subset of axSpA patients [1].ObjectivesThe aim of this study was to identify novel IgA antibodies in early axSpA patients and to determine their diagnostic potential in combination with previously determined IgG antibodies against UH-axSpA-IgG antigens.MethodsAn axSpA cDNA phage display library constructed from axSpA hip synovium, was used to screen for novel IgA antibodies in plasma from early axSpA patients. The diagnostic value of these antibodies against novel UH-axSpA-IgA and previously identified UH-axSpA-IgG antigens was determined in two independent axSpA cohorts [UH cohort and the Leuven spondyloarthritis biologics cohort (BIOSPAR)], in healthy controls and in patients with chronic low back pain (CLBP) using ELISA.ResultsWe identified antibodies to 7 novel UH-axSpA-IgA antigens, of which 6 correspond to non-physiological peptides and 1 to the human histone deacetylase 3 (HDAC3) protein. IgA antibodies against 2 of these 7 novel UH-axSpA-IgA antigens and IgG antibodies against 2 of 3 the previously identified antigens were significantly more present in axSpA patients from the UH cohort (18/70, 25.7%) and the (Bio)SPAR cohort (26/164, 15.9%), compared to controls with CLBP (2/66, 3%). Antibodies to this panel of 4 antigens were present in 21.1 % (30/142) of patients with early axSpA from the UH and (Bio)SPAR cohorts. The positive likelihood ratio for confirming early axSpA using antibodies to these 4 UH-axSpA antigens was 7.0. So far, no clinical correlation between the novel identified IgA antibodies and inflammatory bowel disease could be identified.ConclusionScreening an axSpA cDNA phage display library for IgA reactivity resulted in the identification of 7 novel UH-axSpA-IgA antigens, of which 2 show promising biomarker potential for the diagnosis of a subset of axSpA patients, in combination with previously identified UH-axSpA-IgG antigens.Reference[1]Quaden D, Vandormael P, Ruytinx P, Geusens P, Corten K, Vanhoof J, et al. Antibodies Against Three Novel Peptides in Early Axial Spondyloarthritis Patients From Two Independent Cohorts. Arthritis Rheumatol. 2020;72(12):2094-105.Acknowledgements:NIL.Disclosure of InterestsNone Declared.