Wendy M. Blumenschein

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.

Interleukin-23-Independent IL-17 Production Regulates Intestinal Epithelial Permeability

Whether interleukin-17A (IL-17A) has pathogenic and/or protective roles in the gut mucosa is controversial and few studies have analyzed specific cell populations for protective functions within the inflamed colonic tissue. Here we have provided evidence for IL-17A-dependent regulation of the tight junction protein occludin during epithelial injury that limits excessive permeability and maintains barrier integrity. Analysis of epithelial cells showed that in the absence of signaling via the IL-17 receptor adaptor protein Act-1, the protective effect of IL-17A was abrogated and inflammation was enhanced. We have demonstrated that after acute intestinal injury, IL-23R(+) γδ T cells in the colonic lamina propria were the primary producers of early, gut-protective IL-17A, and this production of IL-17A was IL-23 independent, leaving protective IL-17 intact in the absence of IL-23. These results suggest that IL-17-producing γδ T cells are important for the maintenance and protection of epithelial barriers in the intestinal mucosa.

Foxp3+ Regulatory T Cells Promote T Helper 17 Cell Development In Vivo through Regulation of Interleukin-2

T helper 17 (Th17) cell development is driven by cytokines including transforming growth factor-β (TGF-β), interleukin-6 (IL-6), IL-1, and IL-23. Regulatory T (Treg) cells can provide the TGF-β inxa0vitro, but their role inxa0vivo remains unclear, particularly because Treg cells inhibit inflammation in many models of Th17 cell-associated autoimmunity. We used mice expressing Diphtheria toxin receptor under control of the Foxp3 promoter to deplete Foxp3(+) Treg cells in adult mice during inxa0vivo Th17 cell priming. Treg cell depletion resulted in a reduced frequency of antigen-specific IL-17 producers in draining lymph nodes and blood, correlating with reduced inflammatory skin responses. In contrast, Treg cells did not promote IL-17 secretion after initial activation stages. Treg cell production of TGF-β was not required for Th17 cell promotion, and neither was suppression of Th1 cell-associated cytokines. Rather, regulation of IL-2 availability and resultant signaling through CD25 by Treg cells was found to play an important role.

Interleukin-23-Induced Transcription Factor Blimp-1 Promotes Pathogenicity of T Helper 17 Cells

Interleukin-23 (IL-23) is a pro-inflammatory cytokine required for the pathogenicity of T helper 17 (Th17) cells but the molecular mechanisms governing this process remain unclear. We identified the transcription factor Blimp-1 (Prdm1) as a key IL-23-induced factor that drove the inflammatory function of Th17 cells. In contrast to thymic deletion of Blimp-1, which causes Txa0cell development defects and spontaneous autoimmunity, peripheral deletion of this transcription factor resulted in reduced Th17 activation and reduced severity of autoimmune encephalomyelitis. Furthermore, genome-wide occupancy and overexpression studies in Th17 cells revealed that Blimp-1 co-localized with transcription factors RORγt, STAT-3, and p300 at the Il23r, Il17a/f, and Csf2 cytokine loci to enhance their expression. Blimp-1 also directly bound to and repressed cytokine loci Il2 and Bcl6. Taken together, our results demonstrate that Blimp-1 is an essential transcription factor downstream of IL-23 that acts in concert with RORγt to activate the Th17 inflammatory program.

Autoimmune Memory T Helper 17 Cell Function and Expansion Are Dependent on Interleukin-23

Interleukin-23 (IL-23) is essential for the differentiation of pathogenic effector T helper 17 (Th17) cells, but its role in memory Th17 cell responses is unclear. Using the experimental autoimmune encephalomyelitis (EAE) model, we report that memory Th17 cells rapidly expanded in response to rechallenge and migrated to the CNS in high numbers, resulting in earlier onset and increased severity of clinical disease. Memory Th17 cells were generated from IL-17+ and RORγt+ precursors, and the stability of the Th17 cell phenotype depended on the amount of time allowed for the primary response. IL-23 was required for this enhanced recall response. IL-23 receptor blockade did not directly impact IL-17 production, but did impair the subsequent proliferation and generation of effectors coexpressing the Th1 cell-specific transcription factor T-bet. In addition, many genes required for cell-cycle progression were downregulated in Th17 cells that lacked IL-23 signaling, showing that a major mechanism for IL-23 in primary and memory Th17 cell responses operates via regulation of proliferation-associated pathways.

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

IL-17A gene transfer induces bone loss and epidermal hyperplasia associated with psoriatic arthritis

BACKGROUNDnPsoriatic arthritis (PsA) is a chronic inflammatory disease characterised by clinical features that include bone loss and epidermal hyperplasia. Aberrant cytokine expression has been linked to joint and skin pathology; however, it is unclear which cytokines are critical for disease initiation. Interleukin 17A (IL-17A) participates in many pathological immune responses; however, its role in PsA has not been fully elucidated.nnnOBJECTIVEnTo determine the role of IL-17A in epidermal hyperplasia and bone destruction associated with psoriatic arthritis.nnnDESIGNnAn in vivo gene transfer approach was used to investigate the role of IL-17A in animal models of inflammatory (collagen-induced arthritis) and non-inflammatory (receptor activator of NF-κB ligand (RANKL)-gene transfer) bone loss.nnnRESULTSnIL-17A gene transfer induced the expansion of IL-17RA(+)CD11b(+)Gr1(low) osteoclast precursors and a concomitant elevation of biomarkers indicative of bone resorption. This occurred at a time preceding noticeable joint inflammation, suggesting that IL-17A is critical for the induction of pathological bone resorption through direct activation of osteoclast precursors. Moreover, IL-17A induced a second myeloid population CD11b(+)Gr1(high) neutrophil-like cells, which was associated with cutaneous pathology including epidermal hyperplasia, parakeratosis and Munros microabscesses formation.nnnCONCLUSIONSnCollectively, these data support that IL-17A can play a key role in the pathogenesis of inflammation-associated arthritis and/or skin disease, as observed in PsA.

T-cell infiltration and clonality correlate with programmed cell death protein 1 and programmed death-ligand 1 expression in patients with soft tissue sarcomas

Patients with metastatic sarcomas have poor outcomes and although the disease may be amenable to immunotherapies, information regarding the immunologic profiles of soft tissue sarcoma (STS) subtypes is limited.

Pembrolizumab in patients with thymic carcinoma: a single-arm, single-centre, phase 2 study

BACKGROUNDnTreatment options are limited for patients with thymic carcinoma. These aggressive tumours are not typically associated with paraneoplastic autoimmune disorders, and strong PD-L1 expression has been reported in thymic epithelial tumours. We aimed to assess the activity of pembrolizumab, a monoclonal antibody that targets PD-1, in patients with advanced thymic carcinoma.nnnMETHODSnWe completed a single-arm phase 2 study of pembrolizumab in patients with recurrent thymic carcinoma who had progressed after at least one line of chemotherapy. This was a single-centre study performed at Lombardi Comprehensive Cancer Center, Georgetown University, Washington, DC, USA. Key inclusion criteria were an Eastern Cooperative Oncology Group performance status of 0-2, no history of autoimmune disease or other malignancy requiring treatment or laboratory abnormality, and adequate organ function. Patients received 200 mg of pembrolizumab every 3 weeks for up to 2 years. The primary objective of the study was the proportion of patients who had achieved a response assessed with Response Evaluation Criteria in Solid Tumors version 1.1. Analysis was per protocol, in all eligible patients. The study is registered with ClinicalTrials.gov, number NCT02364076, and is closed to accrual; we report the final analysis.nnnFINDINGSn41 patients were enrolled from March 12, 2015, to Dec 16, 2016, of whom 40 were eligible and evaluable and one was excluded because of elevated liver enzymes at screening. The median follow-up was 20 months (IQR 14-26). The proportion of patients who achieved a response was 22·5% (95% CI 10·8-38·5); one (3%) patient achieved a complete response, eight (20%) patients achieved partial responses, and 21 (53%) patients achieved stable disease. The most common grade 3 or 4 adverse events were increased aspartate aminotransferase and alanine aminotransferase (five [13%] patients each). Six (15%) patients developed severe autoimmune toxicity, including two (5%) patients with myocarditis. There were 17 deaths at the time of analysis, but no deaths due to toxicity.nnnINTERPRETATIONnPembrolizumab is a promising treatment option in patients with thymic carcinoma. Because severe autoimmune disorders are more frequent in thymic carcinoma than in other tumour types, careful monitoring is essential.nnnFUNDINGnMerck & Co.

A colitogenic memory CD4+ T cell population mediates gastrointestinal graft-versus-host disease

Damage to the gastrointestinal tract is a major cause of morbidity and mortality in graft-versus-host disease (GVHD) and is attributable to T cell-mediated inflammation. In this work, we identified a unique CD4+ T cell population that constitutively expresses the β2 integrin CD11c and displays a biased central memory phenotype and memory T cell transcriptional profile, innate-like properties, and increased expression of the gut-homing molecules α4β7 and CCR9. Using several complementary murine GVHD models, we determined that adoptive transfer and early accumulation of β2 integrin-expressing CD4+ T cells in the gastrointestinal tract initiated Th1-mediated proinflammatory cytokine production, augmented pathological damage in the colon, and increased mortality. The pathogenic effect of this CD4+ T cell population critically depended on coexpression of the IL-23 receptor, which was required for maximal inflammatory effects. Non-Foxp3-expressing CD4+ T cells produced IL-10, which regulated colonic inflammation and attenuated lethality in the absence of functional CD4+Foxp3+ T cells. Thus, the coordinate expression of CD11c and the IL-23 receptor defines an IL-10-regulated, colitogenic memory CD4+ T cell subset that is poised to initiate inflammation when there is loss of tolerance and breakdown of mucosal barriers.