Overview
The aim of this study is to investigate the serum levels of lysyl hydroxylase, lysyl oxidase, and the lysyl oxidase-like enzymes in patients with different stages of knee osteoarthritis and to compare these findings with those of healthy control subjects.
Description
Osteoarthritis (OA) is a chronic degenerative disease affecting synovial joints, characterized by structural abnormalities of the hyaline articular cartilage, subchondral bone loss, increased synovial vascularity, tissue hypertrophy, and ligament or tendon instability. These changes lead to pain, swelling, and reduced range of motion. The pathogenesis of OA involves inflammation, genetic predisposition, mechanical stress, biochemical alterations, and environmental factors, all of which disrupt the balance between cartilage synthesis and degradation.
The extracellular matrix (ECM) of articular cartilage is composed mainly of collagen, proteoglycans, and non-collagenous proteins, providing biomechanical strength and resilience. Collagen cross-linking, which stabilizes the ECM, depends on post-translational modifications regulated by specific enzymes such as lysyl hydroxylase and lysyl oxidase.
Lysyl hydroxylases catalyze the hydroxylation of lysine residues to hydroxylysine, a key step in collagen cross-link formation. Lysyl oxidase (LOX) and its related isoenzymes (LOXL1-4) are copper-dependent amine oxidases that mediate oxidative deamination of lysine and hydroxylysine residues, forming aldehydes that initiate covalent cross-links between collagen and elastin molecules. Proper LOX activity is crucial for maintaining the mechanical integrity of cartilage, while dysregulation of LOX family enzymes may contribute to matrix fragility and degeneration.
The expression and activity of LOX family enzymes in OA cartilage appear to vary by disease stage. LOXL2 and LOXL3 have been implicated in both anabolic and catabolic responses, suggesting complex regulatory roles. Understanding these enzyme dynamics may provide insights into the pathophysiology of OA and identify potential biomarkers or therapeutic targets.
The present study aims to evaluate serum levels of lysyl hydroxylase, lysyl oxidase, and LOXL1-4 in patients with different stages of knee osteoarthritis and compare them with healthy control subjects.
Eligibility
Inclusion Criteria:
- Female participants aged between 40 and 70 years.
- Diagnosed with knee osteoarthritis according to clinical and radiographic criteria, and presenting to the Department of Physical Medicine and Rehabilitation, Afyonkarahisar Health Sciences University (AFSU).
- Body Mass Index (BMI) between 18.5 and 40 kg/m².
Exclusion Criteria:
- Presence of metabolic diseases or severe comorbidities, including uncontrolled diabetes mellitus, chronic kidney disease (GFR \< 60 mL/min/1.73 m²), liver failure, malignancy, severe cardiovascular disease, chronic respiratory disorders, or chronic intestinal diseases.
- Any inflammatory arthritis or other rheumatologic disease with related signs or symptoms.
- History of knee trauma involving cruciate ligaments or menisci within the past 3 months.
- Secondary osteoarthritis due to other joint disorders such as septic arthritis, avascular necrosis, or Paget's disease.
- History of previous knee surgery.
- Recent intra-articular injection to the knee joint within the last 3 months.
