IL-23 is a heterodimeric cytokine composed of a p19 subunit and the p40 subunit of IL-12. IL-23 has proinflammatory activity, inducing IL-17 secretion from activated CD4+ T cells and stimulating the proliferation of memory CD4+ T cells. We investigated the pathogenic role of IL-23 in CD4+ T cells in mice lacking the IL-1R antagonist (IL-1Ra−/−), an animal model of spontaneous arthritis. IL-23 was strongly expressed in the inflamed joints of IL-1Ra−/− mice. Recombinant adenovirus expressing mouse IL-23 (rAd/mIL-23) significantly accelerated this joint inflammation and joint destruction. IL-1β further increased the production of IL-23, which induced IL-17 production and OX40 expression in splenic CD4+ T cells of IL-1Ra−/− mice. Blocking IL-23 with anti-p19 Ab abolished the IL-17 production induced by IL-1 in splenocyte cultures. The process of IL-23-induced IL-17 production in CD4+ T cells was mediated via the activation of Jak2, PI3K/Akt, STAT3, and NF-κB, whereas p38 MAPK and AP-1 did not participate in the process. Our data suggest that IL-23 is a link between IL-1 and IL-17. IL-23 seems to be a central proinflammatory cytokine in the pathogenesis of this IL-1Ra−/− model of spontaneous arthritis. Its intracellular signaling pathway could be useful therapeutic targets in the treatment of autoimmune arthritis.

IL-23p19 is over-expressed in RA synovial fibroblasts and IL-17 appears to up-regulate the expression of IL-23p19 in RA synovial fibroblasts via PI3-kinase/Akt, NF-kappaB- and p38-MAPK-mediated pathways. These results suggest that a disruption of interaction between IL-17 and IL-23p19 may provide a new therapeutic approach in the treatment of RA.

Computed tomography (CT) plays an important supplementary role in the evaluation of patients with congenital heart disease (CHD). Fast multisection spiral CT can be used to obtain isotropic volume data, and high-quality two- and three-dimensional multiplanar reformatted images can be created to accurately and systematically delineate the normal and pathologic morphologic features of the cardiovascular system. CT may be technically challenging and demanding in uncooperative young children. However, it can be used to systematically evaluate the aorta, pulmonary artery, pulmonary vein, cardiac chambers and ventriculoarterial connection, relationship between the upper lobe bronchi and pulmonary arteries, coronary artery, valves, systemic veins (superior vena cava, inferior vena cava, hepatic veins), and visceral situs with a step-by-step approach. This approach may be helpful in understanding the anatomy of the cardiovascular system in CHD patients. CT has both advantages and disadvantages in evaluating patients with CHD. Nevertheless, it is useful in this setting, and radiologists who perform CT in young children with CHD should be familiar with the advantages and disadvantages of CT and with the normal anatomy and typical pathologic conditions in affected patients.