Association of serum angiopoietin-like proteins types 2, 3 and 4 with clinical manifestations of osteoarthritis

Hyperactivity of angiopoietin-like proteins (ANGPTL) involved in persistence of chronic inflammation may lead to progression of different arthropathies. The purpose of the study was to evaluate interrelations between serum angiopoietin-like proteins types 2, 3 and 4 with clinical and laboratory characteristics of osteoarthritis (ОА) and comorbid conditions. We have examined 42 OA patients (females, 78.6%; aged 59.2±8.7 years; mean disease duration of 8.9±5.5 years) More severe joint damage (assessed as radiological stage) was accompanied by an increased levels of ANGPTL type 4 (p = 0.014). The group of OA patients with synovitis had significantly higher rates of type 2 and type 4 ANGPTL than patients without synovitis (p = 0.039 and p = 0.021, respectively). The content of type 4 ANGPTL was also significantly higher in patients with increased values of ESR and C-reactive protein (CRP) (p = 0.018). The associated co-morbidities in OA patients were as follows: obesity (40.5%), arterial hypertension (AH) (38%) and features of metabolic syndrome (MetS) (31%). The levels of type 3 ANGPTL in patients with MetS was higher than in OA patients without MetS (p = 0.024). The levels of type 4 ANGPTL in obese patients was higher than in OA patients with normal body weight (p = 0.027), and the contents of type 3 ANGPTL in this group did not reach the level of statistical significance (p = 0.052). The dispersion analysis also showed a significant effect of obesity degree on the level of type 4 ANGPTL (p = 0.034). The levels of ANGPTL types 2, 3 and 4 did not differ between the groups of OA patients with/without AH (p = 0.11, p = 0.055 and p = 0.09, respectively). However, when comparing patients with different degrees of AH, the difference in ANGPTL type 3 levels reached the level of statistical significance (p = 0.049). In summary, ANGPTLs showed different dependence on the comorbid background in patients with OA: type 2 ANGPTL is associated with inflammatory processes in joints; type 3 ANGPTL correlates with presence of MetS and severity of AH. Type 4 ANGPTL is associated with obesity, inflammation and severity of joint damage.