Robert A. Kastelein

Cutting Edge: A Critical Functional Role for IL-23 in Psoriasis

Interleukin-23 is a key cytokine involved in the generation of Th17 effector cells. Clinical efficacy of an anti-p40 mAb blocking both IL-12 and IL-23 and disease association with single nucleotide polymorphisms in the IL23R gene raise the question of a functional role of IL-23 in psoriasis. In this study, we provide a comprehensive analysis of IL-23 and its receptor in psoriasis and demonstrate its functional importance in a disease-relevant model system. The expression of IL-23 and its receptor was increased in the tissues of patients with psoriasis. Injection of a mAb specifically neutralizing human IL-23 showed IL-23–dependent inhibition of psoriasis development comparable to the use of anti-TNF blockers in a clinically relevant xenotransplant mouse model of psoriasis. Together, our results identify a critical functional role for IL-23 in psoriasis and provide the rationale for new treatment strategies in chronic epithelial inflammatory disorders.

Biomarkers of Therapeutic Response in the IL-23 Pathway in Inflammatory Bowel Disease.

OBJECTIVES:Interleukin-23 (IL-23) has emerged as a new therapeutic target for the treatment of inflammatory bowel disease (IBD). As biomarkers of disease state and treatment efficacy are becoming increasingly important in drug development, we sought to identify efficacy biomarkers for anti-IL-23 therapy in Crohns disease (CD).METHODS:Candidate IL-23 biomarkers, downstream of IL-23 signaling, were identified using shotgun proteomic analysis of feces and colon lavages obtained from a short-term mouse IBD model (anti-CD40 Rag2−/−) treated preventively with monoclonal antibodies (mAbs) to the IL-23 receptor (IL-23R). The biomarkers were then measured in an IBD T-cell transfer model treated therapeutically with a mAb to IL-23 (p19), confirming their association with IBD. To assess the clinical relevance of these markers, we assessed their concentrations in clinical serum, colon tissue, and feces from CD patients.RESULTS:We identified 57 proteins up or downregulated in diseased animals that returned to control values when the mice were treated with mAbs to IL-23R. Among those, S100A8, S100A9, regenerating protein 3β (REG), REG3γ, lipocalin 2 (LCN2), deleted in malignant tumor 1 (DMBT1), and macrophage migration inhibitory factor (MIF) mRNA levels correlated with disease score and dose titration of mAbs to IL-23R or IL-23(p19). All biomarkers, except DMBT1, were also downregulated after therapeutic administration of mAbs to IL-23(p19) in a T-cell transfer IBD mouse model. In sera from CD patients, we confirmed a significant upregulation of S100A8/A9 (43%), MIF (138%), pancreatitis-associated protein (PAP, human homolog of REG3β/γ; 49%), LCN2 (520%), and CCL20 (1280%), compared with control samples, as well as a significant upregulation of S100A8/A9 (887%), PAP (401%), and LCN2 (783%) in human feces from CD patients compared with normal controls.CONCLUSIONS:These studies identify multiple protein biomarkers downstream of IL-23 that could be valuable tools to assess the efficacy of this new therapeutic agent.Clinical and Translational Gastroenterology (2012) 3, e10; doi:10.1038/ctg.2012.2; published online 16 February 2012

Interleukin 23 is critical in the pathogenesis of spondyloarthropathy and acts on a novel population of interleukin 23R+entheseal resident cells

Abstract Spondyloarthropathy is characterised by inflammation, bone erosion, and new bone formation at the entheseal insertions of tendons and ligaments to bone. Lack of understanding of the underlying mechanisms that drive entheseal disease has seriously inhibited design of therapeutics. Although anti-tumour necrosis factor (TNF) therapy reduces signs and symptoms of inflammation, residual inflammation continues and bone growth is not inhibited. This suggests that TNF is not the optimum target to modify entheseal disease. We previously demonstrated that interleukin (IL) 23 is pivotal in autoimmune inflammation. Recently, genetic variants in the IL-23 receptor (IL23R) have been associated with development of spondyloarthropathy. Moreover, HLA-B27 (present in 90% of patients with ankylosing spondylitis) as well as associated bowel inflammation have been shown to induce IL-23 expression. However, the site and mechanism of action of IL23 are unknown and the reason why such dysregulation of IL23 is associated with inflammation specifically at the enthesis has been inexplicable. We now demonstrate that the entheses and aortic root contain a novel population of resident IL23R+ T cells, which allow the tissue to rapidly respond to IL23. Intravital microscopy reveals that these cells display an extremely restricted entheseal localisation and are absent from synovium and tendon proper. The cells express the molecule PLZF, which allows them to respond to cytokines extremely rapidly, and indeed entheses respond within hours to IL23 in vitro. Moreover, IL-23 expression in vivo in mice is sufficient by itself to rapidly induce the hallmark features of spondyloarthropathy with development of exceedingly specific enthesitis, aortitis, and typical bone erosion and new bone formation. The highly restricted distribution of IL23R+ cells provides the fundamental basis for the anatomical localisation of inflammation observed in spondyloarthropathy, as well as allowing a unified understanding of the genetic associations. These findings suggest that neutralisation of IL23 may be a truly disease modifying therapeutic approach. Funding Merck.