Pro-inflammatory and anti-inflammatory cytokines as candidate markers in the diagnosis and assessment of Crohn's disease activity

Introduction: We evaluated the diagnostic characteristics of interleukin (IL)-12, interferon (IFN)-gamma, IL-10 and IL-19 in the diagnosis and assessment of Crohn's disease (CD) activity. Material and methods: We studied 49 CD patients assigned to the active (33 patients) and inactive (16 patients) disease subgroups and 31 healthy controls. Serum cytokines were measured using ELISA. Cytokine levels and their multiplication results were compared between the groups and their diagnostic characteristics were assessed. Results: The levels of the studied cytokines except IL-10 and their multiplication results were significantly higher in CD patients than in controls (p < 0.0001-0.007) and in patients with active than inactive disease (p < 0.0001-0.023). In the diagnosis of CD, the [CRP] x [IL-19] and [IL-6] x [IFN-gamma] results had a specificity of 0.96, positive predictive value (PPV) of 0.97 and positive likelihood ratio (LR+) of 15.0 and 15.5, respectively, while serum IL-19 and the [IL-6] x [IL-12] and IFN-gamma] x [IL-12] results had a sensitivity of 0.9-0.96, negative PV (NPV) of 0.75-0.86 and negative LR (LR-) of 0.09-0.18. The area under the ROC curve (AUC) for these markers was 0.776-0.807. In the diagnosis of active CD, the [CRP] x [IL-10] and [CRP] x [IL-19] results had a specificity of 0.98, PPV of 0.96, LR+ of 33.4 and 30.5, and AUC of 0.896 and 0.895, respectively. Serum IFN-gamma and the [CRP] x [IFN-gamma], [CRP] x [IL-12] and [IFN-gamma] x [IL-19] results had diagnostic sensitivity of 0.77-0.94, NPV of 0.86-0.93, LR-of 0.11-0.24 and AUC of 0.781-0.904. Conclusions: Serum IFN-gamma, IL-19 and some of the results of the studied cytokine levels' multiplication showed promising diagnostic performance in the diagnosis of CD and its active form, which requires further validation.