Effects of high mobility group box protein-1, interleukin-1β, and interleukin-6 on cartilage matrix metabolism in three-dimensional equine chondrocyte cultures

Abstract

The effects of high mobility group box protein (HMGB)-1, interleukin (IL)-1β, and IL-6 on equine articular chondrocytes were investigated, with emphasis on detecting differences between anatomical sites exposed to different loading in vivo, using three-dimensional (3D) cell cultures established with chondrocytes from dorsal radial facet (DRF, highly loaded) and palmar condyle (PC, less loaded) of the third carpal bone (C3). Expression of important genes involved in cartilage metabolism, presence of glycosaminoglycans and cartilage oligomeric matrix protein (COMP) in pellets, and concentrations of matrix metalloproteinase (MMP)-13 and aggrecan epitope CS 846 were evaluated. Compared to controls, IL-1β treatment increased gene expression of versican, matrix-degrading enzymes, and tissue inhibitor of metalloproteinase (TIMP)-1, and decreased aggrecan and collagen type I and type II expression. In addition, IL-1β-treated pellets showed decreased safranin O staining and increased COMP immunostaining and MMP-13 concentrations in culture supernatants. Effects of IL-6 and HMGB-1 on gene expression were variable, although upregulation of Sry-related high-mobility group box 9 (Sox9) was often present and statistically increased in HMGB-1-treated pellets. Response to cytokines rarely differed between DRF and PC pellets. Thus, site-associated cartilage deterioration in equine carpal osteoarthritis (OA) is not explained by topographically different responses to inflammatory mediators. Differences in gene expressions of structural matrix proteins in untreated DRF and PC pellets were noted in the youngest horses, which may indicate differences in the chondrocytes potential to produce matrix in vivo. Overall, a strong catabolic response was induced by IL-1β, whereas slight anabolic effects were induced by IL-6 and HMGB-1.

Proteomic Analysis of Tendon Extracellular Matrix Reveals Disease Stage-specific Fragmentation and Differential Cleavage of COMP (Cartilage Oligomeric Matrix Protein)

“…However, it was not possible to maintain good cell viability in tendon explants beyond 5 days, which is why this time interval was selected as maximal for this study. The increased release of COMP with IL-1β supports a catabolic role of IL-1β in tendon similar to that reported for cartilage (28, 39, 40), which was further confirmed by the abrogating effects of IL-1Ra. Firocoxib but not Ilomastat inhibited IL-1β-induced COMP release.…”

“…The role of inflammatory cytokines in non-collagenous matrix breakdown has been investigated extensively in cartilage in vitro and in vivo as typified by loss of COMP and proteoglycans (28, 39–42). Whereas tendon and tendon fibroblasts produce and respond to cytokine stimulation (43), their role in the specific cleavage of ECM proteins is less well documented (28, 39, 40).…”

“…The role of inflammatory cytokines in non-collagenous matrix breakdown has been investigated extensively in cartilage in vitro and in vivo as typified by loss of COMP and proteoglycans (28, 39–42). Whereas tendon and tendon fibroblasts produce and respond to cytokine stimulation (43), their role in the specific cleavage of ECM proteins is less well documented (28, 39, 40). The ability to detect specific proteolytic cleavage sites is necessary to understand tendon ECM degradative mechanisms that are disease stage-specific for both targeted therapeutic interventions as well as to identify neo-terminal peptide fragments for developing markers for sub-clinical disease for preventative strategies (41).…”

Effects of cleavage by a disintegrin and metalloproteinase with thrombospondin motifs-4 on gene expression and protein content of versican and aggrecan in the digital laminae of horses with starch gruel–induced laminitis

“…32 Furthermore, exposure of equine articular cartilage to interleukin-1β elicits increases in gene expression of versican but decreases in gene expression of aggrecan. 33 …”

IL‐1β mediating high mobility group box protein‐1 expression in condylar chondrocyte during temporomandibular joint inflammation

“…For decades, HMGB‐1 was believed to be a potential trigger of OA and the role of HMGB‐1 in other synovial joint OA was investigated but not confirmed. For example, HMGB‐1 could induce slight anabolic effects in OA . On the other hand, osteochondral fragments were found to be a source of inflammatory mediators in equine OA, because of the presence of IL‐6 and extracellular HMGB‐1 in the fragment .…”