Different serum levels of interleukin-23 in patients affected by peripheral arterial disease

Abstract

Recently, we demonstrated the involvement of interleukin (IL)-23 in peripheral arterial disease (PAD). IL-23 is mainly involved in the generation of a new subset of effector T cells (Th17) that could be characterised by the ability to produce a unique set of inflammatory cytokines, such as IL-17A, IL-17F, IL-6 and tumour necrosis factor-a, that play an important role in vascular inflammation. We showed that serum levels of this cytokine are higher in three times in connection with surgical treatment (T0: 24 h before, T1: 24 h after, T2: five days after) in patients with lower extremity PAD stage IV compared to controls. Afterwards, we retrospectively analysed whether IL23 has a univocal behaviour in PAD patients or is influenced by its initial values. Therefore, we divided the 29 patients of the previous study into two subgroups: group A (14 patients) with IL-23 levels at T0 8 pg/ml. The cut-off value was established following the controls mean value (8.08 8.62 pg/ml). Data were presented as mean standard deviation (SD). Differences between two paired groups were analysed by the Wilcoxon test and between more than two paired groups by Friedman test. Relationship between variables was evaluated with the ANOVA linear regression which identified the dependent variable in IL-23 and the independent variables in parameters such as age, sex, allergy, smoking, diabetes, hypertension, ischemic heart disease, autoimmune diseases, chronic renal failure and dialysis and use of drugs. Statistical significance was set at p< 0.05. IL-23 serum levels in group A at three times (T01⁄4 3.65 2.23 pg/ml; T11⁄4 6.05 2.5 pg/ml; T21⁄4 8.22 2.77 pg/ml) (Figure 1) showed a statistically significant progressive increase (p< 0.0001) that we did not find in group B (T01⁄4 27.20 26.14 pg/ml; T11⁄4 25.49 30.37 pg/ml; T21⁄4 21.44 21.49 pg/ml; p1⁄4 0.627) (Figure 2). Specifically in group A, both between T0-T1 and T1-T2, the IL-23 serum levels increased in 13 of 14 patients (p1⁄4 0.001 and p1⁄4 0.003, respectively). In group B, both between T0-T1 and T1-T2, the IL-23 serum levels increased in seven of 15 patients (p1⁄4 0.650 and p1⁄4 0.496, respectively). Using ANOVA linear regression, we did not find a relationship between IL-23 serum levels and parameters such as age, sex, allergy, smoking, diabetes, hypertension, ischemic heart disease, autoimmune diseases, chronic renal failure and dialysis. It was also evaluated whether the use of drugs could influence IL-23 serum levels. The linear regression showed no relationship. In another study, Jiang et al. reported increased serum IL-23 levels in patients with Behcet disease after cataract surgery; the cytokine levels did not consistently change in a control group of uncomplicated cataract patients after surgery. The authors hypothesised an underlying inflammation and immune hypersensitivity reaction in patients with Behcet disease that is provoked by the cataract trauma. Our study shows that the increasing IL-23 levels after surgery is influenced by initial levels of this