Link N suppresses interleukin-1β-induced biological effects on human osteoarthritic cartilage

Abstract

Osteoarthritis (OA) is a disease of diarthrodial joints associated with extracellular matrix proteolytic degradation under inflammatory conditions, pain and disability. Currently, there is no therapy to prevent, reverse or modulate the disease course. The present study aimed at evaluating the regenerative potential of Link N (LN) in human OA cartilage in an inflammatory milieu and determining if it could affect pain-related behaviour in a knee OA mouse injury model. Osteo-chondro OA explants and OA chondrocytes were treated with LN in the presence of interleukin-1β (IL-1β) to simulate an osteoarthritic environment. Quantitative von Frey polymerase chain reaction and Western blotting were performed to determine the effect of LN on matrix protein synthesis, catabolic enzymes, cytokines and nerve growth factor expression. Partial medial meniscectomy (PMM) was performed on the knee of C57BL/6 mice and, 12 weeks post-surgery, mice were given a 5 µg intra-articular injection of LN or phosphate-buffered saline. A von Frey test was conducted over 24 h to measure the mechanical allodynia in the hind paw. LN modulated proteoglycan and collagen synthesis in human OA cartilage through inhibition of IL-1βinduced biological effects. LN also supressed IL-1β-induced upregulation of cartilage-degrading enzymes and inflammatory molecules in OA chondrocytes. Upon investigation of the canonical signalling pathways IL-1β and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), LN resulted to significantly inhibit NF-κB activation in a dose-dependent manner. In addition, LN suppressed mechanical allodynia in an OA PMM mouse model. Results supported the concept that LN administration could have therapeutic potential in OA.

Chitosan-based hydrogels supplemented with gelatine and Link N enhance extracellular matrix deposition by encapsulated cells in a degenerative intervertebral disc environment

“…This finding was in an agreement with earlier data (Alaqeel et al, 2020) showing that LN can restore GAG production to healthy control levels in human osteoarthritic cartilage when exposed to IL-1β, an inflammatory cytokine known for its catabolic activities in cartilage and IVD (Masuda and An, 2004;Yang et al, 2015). The strong effect of LN observed in these conditions could be partly explained by the fact that LN inhibits IL-1β signalling pathways (Alaqeel et al, 2020). Interestingly, the study's findings demonstrated that in a degenerative medium, the level of GAG achieved with LN reached similar levels to those observed with TGF-β.…”

“…Data indicated that, under conditions mimicking the degenerative disc environment, LN induced a strong increase in GAG production by NP cells. This finding was in an agreement with earlier data (Alaqeel et al, 2020) showing that LN can restore GAG production to healthy control levels in human osteoarthritic cartilage when exposed to IL-1β, an inflammatory cytokine known for its catabolic activities in cartilage and IVD (Masuda and An, 2004;Yang et al, 2015). The strong effect of LN observed in these conditions could be partly explained by the fact that LN inhibits IL-1β signalling pathways (Alaqeel et al, 2020).…”

“…The authors reported that this may be related to the low-grade of cartilage pathology occurring at this site in the model. This observation raises the possibility that LN exerts its influence once matrix degradation exceeds turnover (Alaqeel et al, 2020;Antoniou et al, 2019). In contrast, TGF-β increased GAG production in both normal and degenerative conditions.…”

Link N as a therapeutic agent for discogenic pain

“…Another mechanism by which Link N may be inhibiting the induction of NTs by inflammatory cytokines in IVD cells is by decreasing cytokine signaling pathway. In our unpublished work, human chondrocytes coexposed to IL‐1β and Link N demonstrated a reduced activation of nuclear factor‐κB when compared to chondrocytes treated with IL‐1β alone . Since the IL‐1β signaling pathway is important in mediating NTs upregulation, factors that inhibit IL‐1β receptor signaling (ie, IL‐1 receptor antagonist) may play a role in regulating the pathogenesis of degenerative IVD disease.…”

Osteoarthritis: Novel Molecular Mechanisms Increase Our Understanding of the Disease Pathology

“…Link protein is a glycoprotein that interacts with and connects hyaluronic acid and aggrecan, and thus stabilizes the cartilage ECM. Recent studies have demonstrated that a short N-terminal fragment has anabolic functions, promotes matrix production and decreases the activity of catabolic enzymes, including MMPs, in degenerating intervertebral discs [ 87 ] but also human OA cartilage [ 88 ]. The fragmentation of the perifibrillar proteoglycans decorin, biglycan, lumican and keratocan is elevated in degenerating human meniscus, knee and hip articular cartilages compared with age-matched macroscopically normal and control tissues [ 89 ].…”