This study aimed to define the histopathology of degenerated humeral head cartilage and synovial inflammation of the glenohumeral joint in patients with omarthrosis (OmA) and cuff tear arthropathy (CTA). Additionally, the potential of immunohistochemical tissue biomarkers in reflecting the degeneration status of humeral head cartilage was evaluated. Specimens of the humeral head and synovial tissue from 12 patients with OmA, seven patients with CTA, and four body donors were processed histologically for examination using different histopathological scores. Osteochondral sections were immunohistochemically stained for collagen type I, collagen type II, collagen neoepitope C1,2C, collagen type X, and osteocalcin, prior to semiquantitative analysis. Matrix metalloproteinase (MMP)-1, MMP-3, and MMP-13 levels were analyzed in synovial fluid using enzyme-linked immunosorbent assay (ELISA).Aims
Methods
Intervertebral disc (IVD) degeneration is responsible for severe clinical symptoms including chronic back pain. Galectins are a family of carbohydrate-binding proteins, some of which can induce functional disease markers in IVD cells and other musculoskeletal diseases. Galectins −4 and −8 were shown to trigger disease-promoting activity in chondrocytes but their effects on IVD cells have not been investigated yet. This study elucidates the role of galectin-4 and −8 in IVD degeneration. Immunohistochemical evidence for the presence of galectin-4 and −8 in the IVD was comparatively provided in specimens of 36 patients with spondylochondrosis, spondylolisthesis, or spinal deformity. Confocal microscopy revealed co-localization of galectin-4 and −8 in chondrocyte clusters of degenerated cartilage. The immunohistochemical presence of galectin-4 correlated with histopathological and clinical degeneration scores of patients, whereas galectin-8 did not show significant correlations. The specimens were separated into annulus fibrosus (AF), nucleus pulposus (NP) and endplate, which was confirmed histologically. Separate cell cultures of AF and NP (n=20) were established and characterized using cell type-specific markers. Potential binding sites for galectins including sialylated N-glycans and LacdiNAc structures were determined in AF and NP cells using LC/ESI-MS-MS. To assess galectin functions, cell cultures were treated with recombinant galectin-4 or −8, in comparison to IL-1β, and analyzed using RT-qPCR and In-cell Western blot. In vitro, both galectins triggered the induction of functional disease markers (CXCL8 and MMP3) on mRNA level and activated the nuclear factor-kB pathway. NP cells were significantly more responsive to galectin-8 and Il-1β than AF cells. Phosphorylation of p-65 was time-dependently induced by both galectins in both cell types to a comparable extent. Taken together, this study provides evidence for a functional role of glycobiological processes in IVD degeneration and highlights galectin-4 and −8 as regulators of pro-inflammatory and degrative processes in AF and NP cells.
