Relation between serum IL-17 level and risk of osteoporotic fracture in premenopausal rheumatoid arthritis patients: Clinical, radiological and laboratory studies

Is interleukin-17 implicated in early knee osteoarthritis pathogenesis as in rheumatoid arthritis?

Background

Interleukin-17 (IL-17) is a cytokine that promotes activation of multiple catabolic pathways resulting in cartilage and tissue damage. It has features making it increasingly attractive as a biological marker, especially in rheumatoid arthritis (RA) and osteoarthritis (OA). However, its expression is heterogeneous; not all patients’ exhibit high IL-17 levels, and its level along the disease course is still challenging to predict.

Aim of the work

The objectives of this study were to compare serum IL-17 levels in patients with early knee OA and in RA patients, to determine its correlation with disease activity in RA and to determine if it is correlated with functional scores in both RA and OA.

Subjects and methods

Twenty early knee OA patients (32.7 ± 3.7) years were included. Diagnosis of early OA was based on Luyten et al. 2012 early knee OA classification (early OA 2012). This study also included 25 RA patients aged 32.8 ± 5.1 years, and the diagnosis was according to 2010 ACR-EULAR classification criteria for RA. The current work also included a control group of 20 healthy volunteers aged 31.9 ± 3.2 years. The serum IL-17 level was assessed by using the ELISA technique.

Results

Serum IL-17 level was significantly high in early knee OA patients (5.2 pg/ml) and was significantly higher in RA patients (5.9 pg/ml) compared to the control group (4.9 pg/ml) (P < 0.001).

Conclusions

The increased serum IL-17 level in patients with early knee OA suggests its pathogenic role in the disease. Serum IL-17 positive correlation with the severity of knee OA-related pain proposes that it may be a potential marker to target for early treatment of knee OA-related pain.

Serum interleukin-17 and estradiol levels in postmenopausal women in relation to osteoporosis

Background

In post-menopausal women, estrogen deficiency leads to instability between bone formation and resorption which is regulated by osteoclastogenic cytokines leading to resorption. Interleukin-17 (IL-17) a proinflammatory cytokine has been found as an important regulator of osteoclast-genesis induced by estrogen deficiency in favor of bone loss in animal studies.

The study aimed to evaluate levels of IL-17 and estrogen (E2) in relation to bone mineral density (BMD) and risk of fracture in postmenopausal women with and without osteoporosis.

Results

IL-17 levels were significantly higher and E2 levels were significantly lower in the osteoporotic group compared to the non-osteoporotic group (P value ≤ 0.01). There was a highly significant difference in DEXA score and FRAX index between two groups: with higher values of FRAX and lower values of DEXA score among osteoporotic group (P value ≤ 0.01). IL-17 was inversely correlated to estrogen level and highly significant negative correlation with DEXA as well as a highly significant positive one with FRAX index. IL-17 serum level was able to diagnose osteoporosis at a cutoff level of > 80 pg/mL with 100% sensitivity, 100% specificity, 100% positive predictive value (PPV), and 100% negative predictive value (NPV).

Conclusions

Serum IL-17 was significantly elevated in osteoporotic postmenopausal women when compared to healthy postmenopausal ones and was inversely correlated with estrogen level and DEXA.