Potential Value of Matrix Metalloproteinase-13 as a Biomarker for Osteoarthritis

Catabolic mediators from TLR2-mediated proteoglycan aggrecan peptide-stimulated chondrocytes are reduced by Lactobacillus-conditioned media

In osteoarthritis (OA), extracellular matrix (ECM) digestion by cartilage-degrading enzymes drives cartilage destruction and generates ECM fragments, such as proteoglycan aggrecan (PG) peptides. PG peptides have been shown to induce immunological functions of chondrocytes. However, the role of PG peptides in stimulating catabolic mediators from chondrocytes has not been investigated. Therefore, we aim to determine the effects and its mechanism by which PG peptides induce chondrocytes to produce catabolic mediators in OA. Human chondrocytes were stimulated with IFNγ and various PG peptides either (i) with or (ii) without TLR2 blockade or (iii) with Lactobacillus species-conditioned medium (LCM), a genus of bacteria with anti-inflammatory properties. Transcriptomic analysis, cartilage-degrading enzyme production and TLR2-intracellular signaling activation were investigated. Chondrocytes treated with PG peptides p16-31 and p263-280 increased expression levels of genes associated with chondrocyte hypertrophy, cartilage degradation and proteolytic enzyme production. TLR2 downstream signaling proteins (STAT3, IkBα and MAPK9) were significantly phosphorylated in p263-280 peptide-stimulated chondrocytes. MMP-1 and ADAMTS-4 were significantly reduced in p263-280 peptides-treated condition with TLR2 blockade or LCM treatment. Phosphorylation levels of IkBa, ERK1/2 and MAPK9 were significantly decreased with TLR2 blockade, but only phosphorylation levels of MAPK9 was significantly decreased with LCM treatment. Our study showed that PG peptide stimulation via TLR2 induced cartilage-degrading enzyme production via activation of MAPK, NFκB and STAT3 pathways.

On-demand release of a selective MMP-13 blocker from an enzyme-responsive injectable hydrogel protects cartilage from degenerative progression in osteoarthritis

In osteoarthritis (OA), the degradation of cartilage is primarily driven by matrix metalloprotease-13 (MMP-13). Hence, the inhibition of MMP-13 has emerged as an attractive target for OA treatment. Among the various approaches that are being explored for MMP-13 regulation, blocking of the enzyme with specific binding molecules appears to be a more promising strategy for preventing cartilage degeneration. To enhance effectiveness and ensure patient compliance, it is preferable for the binding molecule to exhibit sustained activity when administered directly into the joint. Herein, we present an enzyme-responsive hydrogel that was designed to exhibit on-demand, the sustained release of BI-4394, a potent and highly selective MMP-13 blocker. The stable and compatible hydrogel was prepared using triglycerol monostearate. The efficacy of the hydrogel to prevent cartilage damage was assessed in a rat model of OA induced by anterior cruciate ligament transection (ACLT). The results revealed that in comparison to the rats administrated weekly with intra-articular BI-4394, the hydrogel implanted rats had reduced levels of inflammation and bone erosion. In comparison to untreated control, the cartilage in animals administered with BI-4394/hydrogel exhibited significant levels of collagen-2 and aggrecan along with reduced MMP-13. Overall, this study confirmed the potential of BI-4394 delivery using an enzyme-responsive hydrogel as a promising treatment option to treat the early stages of OA by preventing further cartilage degradation.

Does Chronic Pancreatitis in Growing Pigs Lead to Articular Cartilage Degradation and Alterations in Subchondral Bone?

Chronic pancreatitis (CP), a progressive inflammatory disease, poses diagnostic challenges due to its initially asymptomatic nature. While CP's impact on exocrine and endocrine functions is well-recognized, its potential influence on other body systems, particularly in young individuals, remains underexplored. This study investigates the hypothesis that CP in growing pigs leads to alterations in articular cartilage and subchondral bone, potentially contributing to osteoarthritis (OA) development. Utilizing a pig model of cerulein-induced CP, we examined the structural and compositional changes in subchondral bone, articular cartilage, and synovial fluid. Histological analyses, including Picrosirius Red and Safranin-O staining, were employed alongside immuno-histochemistry and Western blotting techniques. Our findings reveal significant changes in the subchondral bone, including reduced bone volume and alterations in collagen fiber composition. Articular cartilage in CP pigs exhibited decreased proteoglycan content and alterations in key proteins such as MMP-13 and TGF-β1, indicative of early cartilage degradation. These changes suggest a link between CP and musculoskeletal alterations, underscoring the need for further research into CP's systemic effects. Our study provides foundational insights into the relationship between CP and skeletal health, potentially guiding future pediatric healthcare strategies for early CP diagnosis and management.

The Value of the Monocyte to High-Density Lipoprotein Cholesterol Ratio in Assessing the Severity of Knee Osteoarthritis: A Retrospective Single Center Cohort Study

Background

Inflammatory responses and metabolic abnormalities play essential roles in the pathophysiology of osteoarthritis (OA). Our study aimed to evaluate the association between monocyte-to-high density lipoprotein-cholesterol ratio (MHR) and OA and compared it with other systemic inflammatory markers.

Methods

This study recruited 323 OA cases and age- and sex-matched 283 control participants during the same period. Demographic, clinical, and imaging data and laboratory indicators were obtained from participants' records. Systemic inflammatory markers were calculated for both cohorts. The diagnostic effectiveness of each index for distinguishing patients with OA was analyzed using receiver operating characteristic (ROC) curves. Spearman's method and ordered logistic regression were used to analyze the association between each indicator and Kellgren and Lawrence (KL) grade.

Results

MHR was significantly higher (0.38±0.18 vs 0.25±0.07, p < 0.0001) in OA patients than healthy controls. MHR had the largest area under the ROC curve for predicting OA. Analysis of ordered logistic regression indicated that MHR was a risk factor for OA radiological severity. Spearman correlation analysis indicated that MHR significantly correlates with the KL grade. Moreover, MHR was significantly higher in early stage patients than in healthy controls.

Conclusion

These results suggest that an elevated MHR could reflect knee OA severity and might be a useful marker for diagnosis and monitoring of OA.

Molecular Assessment of Healthy Pathological Articular Cartilages in Physically Active People: A Scoping Review

Physiological aging triggers a cascade of negative effects on the human body and the human joint is only one of the several compartments affected by this irreversible and natural process. Osteoarthritis and cartilage degeneration can cause pain and disability; therefore, identifying the molecular processes underlying these phenomena and the biomarkers produced during physical activity is of critical importance. In the present review, the main goal was to identify and discuss the articular cartilage biomarkers analyzed in studies in which physical or sports activities were adopted and eventually to propose a standard operating procedure for the assessment. Articles collected from Pubmed, Web of Science, and Scopus were scrutinized to detect reliable cartilage biomarkers. The principal articular cartilage biomarkers detected in these studies were cartilage oligomeric matrix protein, matrix metalloproteinases, interleukins, and carboxy-terminal telopeptide. The articular cartilage biomarkers identified in this scoping review may aid in a better comprehension of where research on the topic is heading and offer a viable instrument for streamlining investigations on cartilage biomarker discovery.

Bioinformatics-Led Discovery of Osteoarthritis Biomarkers and Inflammatory Infiltrates

The molecular mechanisms of osteoarthritis, the most common chronic disease, remain unexplained. This study aimed to use bioinformatic methods to identify the key biomarkers and immune infiltration in osteoarthritis. Gene expression profiles (GSE55235, GSE55457, GSE77298, and GSE82107) were selected from the Gene Expression Omnibus database. A protein-protein interaction network was created, and functional enrichment analysis and genomic enrichment analysis were performed using the Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genome (KEGG) databases. Immune cell infiltration between osteoarthritic tissues and control tissues was analyzed using the CIBERSORT method. Identify immune patterns using the ConsensusClusterPlus package in R software using a consistent clustering approach. Molecular biological investigations were performed to discover the important genes in cartilage cells. A total of 105 differentially expressed genes were identified. Differentially expressed genes were enriched in immunological response, chemokine-mediated signaling pathway, and inflammatory response revealed by the analysis of GO and KEGG databases. Two distinct immune patterns (ClusterA and ClusterB) were identified using the ConsensusClusterPlus. Cluster A patients had significantly lower resting dendritic cells, M2 macrophages, resting mast cells, activated natural killer cells and regulatory T cells than Cluster B patients. The expression levels of TCA1, TLR7, MMP9, CXCL10, CXCL13, HLA-DRA, and ADIPOQSPP1 were significantly higher in the IL-1β-induced group than in the osteoarthritis group in an in vitro qPCR experiment. Explaining the differences in immune infiltration between osteoarthritic tissues and normal tissues will contribute to the understanding of the development of osteoarthritis.