Clinical disease activity is associated with anxiety and depressive symptoms in adolescents and young adults with inflammatory bowel disease.

BACKGROUND: Youths with inflammatory bowel disease (IBD) are at risk for developing anxiety and depressive symptoms with a reported 20%-50% prevalence rate. AIMS: This prospective study aimed to: (1) describe the prevalence and severity of anxiety and depressive symptoms in a large Dutch cohort of young IBD patients, and (2) identify demographic and clinical risk factors for anxiety and depression. METHODS: IBD patients (n = 374; 10-25 years) were screened for anxiety, depression and quality of life using validated age-specific questionnaires. Patients with elevated scores for anxiety and/or depressive symptoms received a diagnostic interview assessing psychiatric disorders. Demographic and clinical characteristics were retrieved from medical charts. Multiple logistic regression analysis was performed to identify risk factors for anxiety and/or depression. RESULTS: Patients (mean age 18.9 years, 44.1% male, Crohn's disease 60.4%) had disease in remission (75.4%), or mild, moderate and severe clinical disease activity in, respectively, 19.8%, 2.7% and 2.1%. Mild anxiety/depressive symptoms were present in 35.2% and severe symptoms in 12.4% of patients. Elevated symptoms of either anxiety (28.3%), depression (2.9%) or both (15.8%) were found and did not differ between adolescents (10-17 years) and young adults (18-25 years). Active disease significantly predicted depressive symptoms (odds ratio (OR): 4.6 [95% confidence interval [CI]: 2.4-8.8], P < 0.001). Female gender (OR: 1.7 [95% CI: 1.1-2.7]), active disease (OR: 1.9 [95% CI: 1.1-3.2]) and a shorter disease duration (OR: 1.3 [95% CI: 0.6-1.0) (all P < 0.025) significantly predicted anxiety and/or depressive symptoms. CONCLUSIONS: Considering the high prevalence of anxiety and depressive symptoms, psychological screening is recommended in young IBD patients. Screening facilitates early recognition and psychological treatment. Female patients and patients with active disease are the most vulnerable.

Differential roles of interleukin-18 (IL-18) and IL12 for induction of gamma interferon by staphylococcal cell wall components and superantigens.

The roles of endogenous cytokines induced by either intact staphylococcal microorganisms or staphylococcal exotoxins were examined using human whole-blood cultures. To accomplish this, interleukin-18 binding protein (IL-18BP) and tumor necrosis factor binding protein (TNFbp) were used to neutralize IL-18 and TNF, respectively, whereas an anti-IL-12 monoclonal antibody was used to neutralize IL-12 and the IL-1 receptor antagonist (IL-1Ra) was used to block IL-1 receptors. Heat-killed Staphylococcus epidermidis and Staphylococcus aureus, as well as the staphylococcal superantigens toxic shock syndrome toxin-1 (TSST-1) and staphylococcus enterotoxin B (SEB) induced gamma interferon (IFN-gamma) production. Staphylococcus spp.-induced production of IFN-gamma required the presence of endogenous IL-18, IL-12, and TNF. In contrast, TSST-1-induced IFN-gamma was not significantly reduced in the presence of IL-18BP, anti-IL-12 antibodies, IL-1Ra, or anti-TNFbp. SEB-induced IFN-gamma was significantly inhibited only by anti-IL-12 antibodies, indicating that endogenous IL-18, IL-1, and TNF are not required for SEB-induced IFN-gamma. In conclusion, the mechanisms of IFN-gamma stimulation by intact staphylococcal microorganisms and by exotoxins differ, and this is likely due to the different receptors which are triggered on the cell membranes. In contrast to its role in the interactions between staphylococci and host cells, IL-18 does not appear to play a major role in superantigen-induced IFN-gamma.

Functional reconstitution and regulation of IL-18 activity by the IL-18R beta chain.

IL-18 and IL-12 are major IFN-gamma-inducing cytokines but the unique synergism of IL-18 and IL-12 remains unclear. In the human NK cell line NKO, IL-18R alpha, and IL-18R beta are expressed constitutively but IL-18 did not induce IFN-gamma unless IL-12 was present. COS-1 fibroblasts, which produce the chemokine IL-8 when stimulated by IL-1 beta or TNF-alpha, do not respond to IL-18, despite abundant expression of the IL-18R alpha chain. COS-1 cells lack expression of the IL-18R beta chain. The IL-18R beta cDNA was cloned from a human T-B lymphoblast cDNA library and COS-1 cells were transiently transfected with the IL-18R beta chain and a luciferase reporter. In transfected COS-1 cells, IL-18 induced IL-8 and luciferase in the absence of IL-12 and independently of IL-1 and TNF. Ab against the IL-18R alpha chain, however, prevented IL-18 responsiveness in COS-1 cells transfected with the IL-18R beta chain, suggesting that both chains be functional. In NKO cells and PBMC, IL-12 increased steady-state mRNA levels of IL-18R alpha and IL-18R beta; the production of IFN-gamma corresponded to IL-12-induced IL-18R alpha and IL-18R beta chains. We conclude that functional reconstitution of the IL-18R beta chain is essential for IL-12-independent proinflammatory activity of IL-18-induced IL-8 in fibroblasts. The synergism of IL-18 plus IL-12 for IFN-gamma production is, in part, due to IL-12 up-regulation of both IL-18R alpha and IL-18R beta chains, although postreceptor events likely contribute to IFN-gamma production.

Neutralization of IL-18 reduces neutrophil tissue accumulation and protects mice against lethal Escherichia coli and Salmonella typhimurium endotoxemia.

In addition to stimulating IFN-gamma synthesis, IL-18 also possesses inflammatory effects by inducing synthesis of the proinflammatory cytokines TNF and IL-1beta and the chemokines IL-8 and macrophage inflammatory protein-1alpha. We hypothesized that neutralization of IL-18 would have a beneficial effect in lethal endotoxemia in mice. IL-1beta converting enzyme (ICE)-deficient mice, lacking the ability to process mature IL-18 and IL-1beta, were completely resistant to lethal endotoxemia induced by LPS derived from either Escherichia coli or Salmonella typhimurium. In contrast, both wild-type and IL-1beta-/- mice were equally susceptible to the lethal effects of LPS, implicating that absence of mature IL-18 or IFN-gamma but not IL-1beta in ICE-/- mice is responsible for this resistance. However, IFN-gamma-deficient mice were not resistant to S. typhimurium LPS, suggesting an IFN-gamma-independent role for IL-18. Anti-IL-18 Abs protected mice against a lethal injection of either LPS. Anti-IL-18 treatment also reduced neutrophil accumulation in liver and lungs. The increased survival was accompanied by decreased levels of IFN-gamma and macrophage inflammatory protein-2 in anti-IL-18-treated animals challenged with E. coli LPS, whereas IFN-gamma and TNF concentrations were decreased in treated mice challenged with S. typhimurium. In conclusion, neutralization of IL-18 during lethal endotoxemia protects mice against lethal effects of LPS. This protection is partly mediated through inhibition of IFN-gamma production, but mechanisms involving decreased neutrophil-mediated tissue damage due to the reduction of either chemokines (E. coli LPS) or TNF (S. typhimurium LPS) synthesis by anti-IL-18 treatment may also be involved.