P20 Interleukins as potential factors in assessing the disease activity in systemic lupus erythematosus

Objective Our study aimed to identify correlations concerning the controversial relationship between serum interleukin (IL)-17A and IL-6 levels and their associations with SLE activity and organ involvement. Methods We conducted a prospective cohort study of SLE patients between July and November 2022. Serum concentrations of IL-17A and IL-6 were determined with ELISA method. The disease activity was assessed using SLEDAI. Results We included 88 SLE patients (89.77% women, mean age 51.16 ± 15.37 years-old) with mean disease duration of 10.01 ± 9.36 years; 19.32% had active disease (SLEDAI≥6), while 80.68% had inactive disease. Hematological (68.18%), cutaneous (55.68%), and articular (50%) were the most common manifestations, whereas hypertension (38.64%), osteoporosis (25%) and osteoarthritis (22.73%) were the most prevalent comorbidities. The most frequently reported symptoms were joint pain (76.14%), fatigue (26.14%), xerophthalmia and xerostomia (20.45%). Analysis of the overall group identified mean serum values of 6.32 ± 2.70 pg/ml for IL-17A and 7.46 ± 6.73 pg/ml for IL-6. Mean serum values of IL-6 were higher among patients with active disease (7.30 ± 6.75 pg/ml vs. 8.15 ± 6.80 pg/ml, p = 0.093). In the case of IL-17A, no statistically significant differences were reported depending on disease activity. Interestingly, mean value for IL-6 was higher in male patients (6.87 ± 5.79 pg/ml vs. 12.59 ± 11.50 pg/ml, p = 0,028). We demonstrated a positive correlation between IL-6 and renal involvement (mean serum value for IL-6 of 7.13 ± 4.87 pg/ml) vs. non-renal involvement (7.54 ± 7.11 pg/ml), with statistically significant value. The ROC analysis showed that IL-6 has predictive value for renal involvement in SLE patients (area under the curve = 0.701, p = 0.012, 95% confidence interval 0.551–0.852). A cut-off value of 5.26 has a sensitivity of 68.8% and a specificity of 70% for predicting renal damage in SLE patients (figure 1). No significant statistical difference was identified in IL-17A levels regarding renal involvement. Conclusions Our findings indicate that serum IL-6 is a promising target for renal involvement. Circulating IL-17A showed no positive relationship with SLE activity. Further investigations are needed to determine their sensitivity and specificity as biomarkers of disease activity.