Abstract
The aim of the study was to assess serum levels of interleukin (IL)-18 and IL-10 in systemic lupus erythematosus (SLE) patients and their relationship with disease activity. Thirty patients with SLE and 20 healthy controls were investigated in this study. The serum IL-18 and IL-10 levels were determined using enzyme-linked immunosorbent assay and their correlations with the disease activity were measured using the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), and laboratory parameters, including erythrocyte sedimentation rate, anti-ds DNA antibody, complement 3, and complement 4 levels were analyzed. The serum IL-18 and serum IL-10 levels were significantly higher (mean values 1770.2 ± 360.4 and 842.65 ± 315.37 pg/ml for IL-18 and IL-10, respectively) in SLE patients compared with the controls (110.65 ± 30.37 vs. 76 ± 14.2 pg/ml, respectively, P < 0.001). The increase in serum levels of IL-18 and IL-10 directly and significantly correlated with each other (r = 0.404, P = 0.037). Furthermore, such an increase in the levels of these two cytokines showed a highly significant positive correlation with the SLEDAI scores and anti-ds DNA in the studied patients (P < 0.001). The circulating IL-18 and IL-10 concentrations were significantly elevated in SLE patients and correlated with the SLEDAI score. The study emphasized that there exists an upregulated proinflammatory as well as anti-inflammatory responses in patients with active SLE; however, the anti-inflammatory response is not enough to suppress the active disease. Identifying the exact contribution of the currently studied cytokines might provide future insights for targeted therapeutic strategies in SLE.
Highlights
Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the production of a large quantity of autoreactive antibodies and the formation of immune complexes causing tissue and organ damage [1]
The current research aimed to assess the relationship between SLE disease activity in a population of Egyptian patients in terms of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score and two of the most pathogenetically significant cytokines that have attracted researchers, IL18 and IL-10; in addition, the study tried to explore the possible influence of the serologic profile and the results of the inflammatory biomarkers on the level of these two cytokines
Results of the current study are in agreement with those obtained by Esfandiari et al [33], Wong et al [37], as well as Amerio et al [38], where the researchers illustrated a significant elevation in IL-18 concentration in patients with SLE compared with controls (P < 0.001), which correlated with the SLEDAI activity score in their patients population [39]
Summary
Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by the production of a large quantity of autoreactive antibodies and the formation of immune complexes causing tissue and organ damage [1]. Studies in animal models of SLE suggested that in SLE there is an alteration in Th1 and/ or Th2 lymphocyte function resulting in an enhanced production of cytokines that upregulate autoantibody production by B cells. In murine models of SLE, an altered production of both Th1 (such as IFN-γ, IL-18, and IL-2) and Th2 (such as IL-4 and IL-10) cytokines has been reported [6]. IL-18 acts as a Th1 cytokine, as it promotes both proliferation of Th1 lymphocytes and IFN-production by these cells [7]. IL-18 shares functional similarities with IL-12, which induces the production of IL-18 by activation of natural killer (NK) cells and cytotoxic T lymphocytes [8]
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