Serum and synovial fluid concentrations of interleukin-18 and interleukin-20 in patients with osteoarthritis of the knee and their correlation with other markers of inflammation and turnover of joint cartilage

Abstract

Introduction: Osteoarthritis (OA) is the most common degenerative joint disease, and its aetiology is not entirely known. The aim of the study was to evaluate the involvement of interleukin-18 (IL-18) and interleukin-20 (IL-20) in the pathogenesis of knee OA and their correlations with other markers of inflammation and destruction of joint cartilage, as well as clinical and radiological changes. Material and methods: The study included 25 patients with knee OA and a control group. The concentration of IL-18, IL-20, IL-6, MMP-1, MMP-3, COMP, PG-AG, and YKL-40 in serum and synovial fluid (SF) were determined. We also evaluated radiological lesions of the knee joint according to the Kellgren-Lawrence (K-L) scale, and clinical severity of the disease according to Western Ontario and McMaster Universities Osteoarthritis Index (WOM-AC) and Lequesne Index. Results: The concentrations of IL-18 and IL-20 were statistically significantly higher in serum of patients with OA than in the control group (106.00 ±189.76 pg/ml vs. 16.73 ±16.99 pg/ml, p < 0.001, 17.69 ±13.45 pg/ml vs. 9.76 ±9.00 pg/ml, p < 0.014). Serum concentration of IL-18 positively correlated with MMP-3 (R = 0.58; p = 0.006) and YKL-40 (R = 0.48; p = 0.002). The degree of radiological advancement of OA (K-L scale) correlated positively with clinical evaluation (WOMAC, R = 0.74, p ≤ 0.001; Lequesne Index, R = 0.57, p = 0.003). Conclusions: The analysis of ROC curves showed that IL-20 as well as COMP, MMP-3, and YKL-40 may be diagnostic markers of knee OA. The observations indicate that IL-18 potentially mediates mainly in intra-articular processes and IL-20 could be primarily responsible for the systemic inflammatory reaction.

Serum Biomarkers of Inflammation and Turnover of Joint Cartilage Can Help Differentiate Psoriatic Arthritis (PsA) Patients from Osteoarthritis (OA) Patients

“…Our earlier studies confirm the important role these biomarkers play in the etiopathogenesis of both OA and PsA [ 15 , 16 , 17 ]. Our previous observations in OA patients indicate that IL-18 potentially mediates mainly in intra-articular processes and is responsible for the destruction of joint cartilage.…”

“…The concentration of biomarkers responsible for inflammation and destruction of joint cartilage were analysed in the serum of PsA patients, OA patients, and the control group of healthy individuals (HC): interleukin 6 (IL-6), interleukin 18 (IL-18), interleukin 20 (IL-20), matrix metalloproteinases 1 and 3 (MMP-1, MMP-3), cartilage oligomeric matrix protein (COMP), human cartilage glycoprotein (YKL-40), and aggrecan (PG-AG). Our earlier studies and the others confirm the important role these biomarkers may play in the etiopathogenesis of both OA and PsA [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 ]. Determination of the clinical stage of disease expressed on a Kellgren-Lawrence scale, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Index of Severity for Osteoarthritis of the Knee (Lequesne index) for OA patients and Body Surface Area score (BSA), Psoriasis Area and Severity Index (PASI), Dermatology Life Quality Index (DLQI), and the number of painful (TJC) and swollen joints (SJC) for PsA patients was also conducted [ 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

“…The homogeneity of the studied groups indicates that, in case of scanty and uncharacteristic clinical symptoms, the differentiation between the two diseases does not always have to be clear and simple. Our observations, also from previous publications, indicate that the activity of inflammatory processes and destruction of the articular cartilage may be similar in both groups of patients [ 15 , 16 ] and selective consideration of their activity does not allow for differentiation between the two diseases. Only the multivariate logistic regression analysis of the studied biomarkers allowed us to indicate those that distinguish OA from PsA ( Table 2 ).…”

“…Our previous observations in OA patients indicate that IL-18 potentially mediates mainly in intra-articular processes and is responsible for the destruction of joint cartilage. IL-20 could be primarily responsible for the systemic inflammatory reaction [ 16 ]. Those observations have also shown that IL-20, but also COMP, YKL-40, and MMP-3, may be a sensitive marker in the diagnosis of osteoarthritis [ 16 ].…”

“…IL-20 could be primarily responsible for the systemic inflammatory reaction [ 16 ]. Those observations have also shown that IL-20, but also COMP, YKL-40, and MMP-3, may be a sensitive marker in the diagnosis of osteoarthritis [ 16 ]. In turn, our previous studies among patients with PsA indicate the important role of IL-18, COMP, and MMP-3 in the etiopathogenesis of PsA and that these biomarkers may be a sensitive marker of this disease [ 15 , 17 ].…”