Association between enthesitis/dactylitis resolution and patient-reported outcomes in guselkumab-treated patients with psoriatic arthritis.

OBJECTIVES: To evaluate the association between enthesitis resolution (ER) and dactylitis resolution (DR) and meaningful improvements in patient-reported outcomes (PROs) among biologic-naïve patients with PsA receiving guselkumab in the DISCOVER-2 study. METHODS: Enthesitis and dactylitis, characteristic lesions of PsA, were evaluated by independent assessors using the Leeds Enthesitis Index (range, 0-6) and Dactylitis Severity Score (range, 0-60). Proportions of patients with ER or DR (score = 0) among those with score > 0 at baseline were determined at weeks 24, 52, and 100. PROs included: fatigue (Functional Assessment of Chronic Illness Therapy-Fatigue [FACIT-Fatigue]), pain (0-100 visual analog scale), physical function (Health Assessment Questionnaire-Disability Index [HAQ-DI]), and health-related quality of life (36-item Short-Form Health Survey physical/mental component summary [SF-36 PCS/MCS]). Meaningful responses were defined as: improvements of ≥ 4 for FACIT-Fatigue, ≥ 0.35 for HAQ-DI, and ≥ 5 for SF-36 PCS/MCS and absolute scores of ≤ 15 for minimal pain and ≤ 0.5 for normalized HAQ-DI. Associations between ER/DR status and PRO response status were tested using a Chi-square test. RESULTS: Guselkumab-treated patients with ER were more likely than those without ER to achieve minimal pain (p < 0.001), normalized HAQ-DI (p < 0.001), and PCS response (p < 0.05) at weeks 24, 52, and 100. Patients with DR were more likely than those without DR to achieve FACIT-Fatigue response at week 24 and week 52 (both p ≤ 0.01) and minimal pain at week 24 and normalized HAQ-DI at week 52 (both p ≤ 0.03). CONCLUSION: In biologic-naïve patients with active PsA treated with guselkumab, achieving ER or DR was associated with durable improvements in selected PROs, including those of high importance to patients. TRIAL REGISTRATION: ClinicalTrials.gov ( https://clinicaltrials.gov ) NCT03158285; Registered: May 16, 2017. Key Points • At week 100, 65% and 76% of guselkumab-treated patients achieved enthesitis and dactylitis resolution (ER/DR). • Achieving ER was associated with achieving DR and vice versa through the end of study. • Achieving ER or DR was associated with durable and meaningful improvements in selected patient-reported outcomes.

The IL-17 Family of Cytokines in Health and Disease.

The interleukin 17 (IL-17) family of cytokines contains 6 structurally related cytokines, IL-17A through IL-17F. IL-17A, the prototypical member of this family, just passed the 25th anniversary of its discovery. Although less is known about IL-17B-F, IL-17A (commonly known as IL-17) has received much attention for its pro-inflammatory role in autoimmune disease. Over the past decade, however, it has become clear that the functions of IL-17 are far more nuanced than simply turning on inflammation. Accumulating evidence indicates that IL-17 has important context- and tissue-dependent roles in maintaining health during response to injury, physiological stress, and infection. Here, we discuss the functions of the IL-17 family, with a focus on the balance between the pathogenic and protective roles of IL-17 in cancer and autoimmune disease, including results of therapeutic blockade and novel aspects of IL-17 signal transduction regulation.

LAG3+ Regulatory T Cells Restrain Interleukin-23-Producing CX3CR1+ Gut-Resident Macrophages during Group 3 Innate Lymphoid Cell-Driven Colitis.

Interleukin-22 (IL-22)-producing group 3 innate lymphoid cells (ILC3) maintains gut homeostasis but can also promote inflammatory bowel disease (IBD). The regulation of ILC3-dependent colitis remains to be elucidated. Here we show that Foxp3+ regulatory T cells (Treg cells) prevented ILC3-mediated colitis in an IL-10-independent manner. Treg cells inhibited IL-23 and IL-1ß production from intestinal-resident CX3CR1+ macrophages but not CD103+ dendritic cells. Moreover, Treg cells restrained ILC3 production of IL-22 through suppression of CX3CR1+ macrophage production of IL-23 and IL-1ß. This suppression was contact dependent and was mediated by latent activation gene-3 (LAG-3)-an immune checkpoint receptor-expressed on Treg cells. Engagement of LAG-3 on MHC class II drove profound immunosuppression of CX3CR1+ tissue-resident macrophages. Our study reveals that the health of the intestinal mucosa is maintained by an axis driven by Treg cells communication with resident macrophages that withhold inflammatory stimuli required for ILC3 function.

GITR Agonism Enhances Cellular Metabolism to Support CD8+ T-cell Proliferation and Effector Cytokine Production in a Mouse Tumor Model.

GITR is a costimulatory receptor currently undergoing phase I clinical trials. Efficacy of anti-GITR therapy in syngeneic mouse models requires regulatory T-cell depletion and CD8+ T-cell costimulation. It is increasingly appreciated that immune cell proliferation and function are dependent on cellular metabolism. Enhancement of diverse metabolic pathways leads to different immune cell fates. Little is known about the metabolic effects of GITR agonism; thus, we investigated whether costimulation via GITR altered CD8+ T-cell metabolism. We found activated, GITR-treated CD8+ T cells upregulated nutrient uptake, lipid stores, glycolysis, and oxygen consumption rate (OCR) in vitro Using MEK, PI3Kδ, and metabolic inhibitors, we show increased metabolism is required, but not sufficient, for GITR antibody (DTA-1)-induced cellular proliferation and IFNγ production. In an in vitro model of PD-L1-induced CD8+ T-cell suppression, GITR agonism alone rescued cellular metabolism and proliferation, but not IFNγ production; however, DTA-1 in combination with anti-PD-1 treatment increased IFNγ production. In the MC38 mouse tumor model, GITR agonism significantly increased OCR and IFNγ and granzyme gene expression in both tumor and draining lymph node (DLN) CD8+ T cells ex vivo, as well as basal glycolysis in DLN and spare glycolytic capacity in tumor CD8+ T cells. DLN in GITR-treated mice showed significant upregulation of proliferative gene expression compared with controls. These data show that GITR agonism increases metabolism to support CD8+ T-cell proliferation and effector function in vivo, and that understanding the mechanism of action of agonistic GITR antibodies is crucial to devising effective combination therapies. Cancer Immunol Res; 6(10); 1199-211. ©2018 AACR.

Experimental Lung Metastases in Mice Are More Effectively Inhibited by Blockade of IL23R than IL23.

Tumor-induced immunosuppression is mediated through various mechanisms including engagement of immune checkpoint receptors on effector cells, function of immunoregulatory cells such as regulatory T cells and myeloid-derived suppressor cells, and deployment of immunosuppressive cytokines such as TGFß and IL10. IL23 is a cytokine that negatively affects antitumor immunity. In this study, we investigated whether IL23-deficient (IL23p19-/-) and IL23R-deficient (IL23R-/-) mice phenocopied each other, with respect to their tumor control. We found that IL23R-/- mice had significantly fewer lung metastases compared with IL23p19-/- mice across three different experimental lung metastasis models (B16F10, LWT1, and RM-1). Similarly, IL23R blocking antibodies were more effective than antibodies neutralizing IL23 in suppressing experimental lung metastases. The antimetastatic activity of anti-IL23R was dependent on NK cells and IFNγ but independent of CD8+ T cells, CD4+ T cells, activating Fc receptors, and IL12. Furthermore, our data suggest this increased antitumor efficacy was due to an increase in the proportion of IFNγ-producing NK cells in the lungs of B16F10 tumor-bearing mice. Anti-IL23R, but not anti-IL23p19, partially suppressed lung metastases in tumor-bearing mice neutralized for IL12p40. Collectively, our data imply that IL23R has tumor-promoting effects that are partially independent of IL23p19. Blocking IL23R may be more effective than neutralizing IL23 in the suppression of tumor metastases. Cancer Immunol Res; 6(8); 978-87. ©2018 AACR.

Dual Roles for Regulatory T-cell Depletion and Costimulatory Signaling in Agonistic GITR Targeting for Tumor Immunotherapy.

Agonistic monoclonal antibodies (mAb) targeting the T-cell receptor coregulatory molecule GITR exert potent therapeutic activities in preclinical tumor models. Although anti-GITR mAb are thought to act by depleting and destabilizing the intratumoral T regulatory cell (Treg) population, the precise mechanism of action is obscure. Here, we addressed this issue using a Treg fate-mapping approach, which revealed that Treg loss was primarily due to cell depletion, with minimal evidence of Treg conversion to a non-Foxp3-expressing population. Further characterization of persisting Tregs following anti-GITR mAb treatment showed that a highly activated subpopulation of CD44hiICOShi intratumoral Tregs were preferentially targeted for elimination, with the remaining Tregs exhibiting a less suppressive phenotype. With these changes in the Treg population, intratumoral CD8+ T cells acquired a more functional phenotype characterized by downregulation of the exhaustion markers PD-1 and LAG-3. This reversal of CD8+ T-cell exhaustion was dependent on both agonistic GITR signaling and Treg depletion, as neither mechanism by itself could fully rescue the exhaustion phenotype. Tests of anti-human GITR antibody MK-4166 in a humanized mouse model of cancer mimicked many of the effects of anti-mouse GITR mAb in syngeneic tumor models, decreasing both Treg numbers and immune suppressor phenotype while enhancing effector responsiveness. Overall, our results show how anti-GITR mAb shifts Treg populations to enable immune attack on tumors, with clinical implications for molecular markers to modify emerging treatments. Cancer Res; 77(5); 1108-18. ©2016 AACR.

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 ß2 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 α4ß7 and CCR9. Using several complementary murine GVHD models, we determined that adoptive transfer and early accumulation of ß2 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.

IL-17A-producing CD30(+) Vδ1 T cells drive inflammation-induced cancer progression.

Although it has been suspected that inflammation is associated with increased tumor metastasis, the exact type of immune response required to initiate cancer progression and metastasis remains unknown. In this study, by using an in vivo tumor progression model in which low tumorigenic cancer cells acquire malignant metastatic phenotype after exposure to inflammation, we found that IL-17A is a critical cue for escalating cancer cell malignancy. We further demonstrated that the length of exposure to an inflammatory microenvironment could be associated with acquiring greater tumorigenicity and that IL-17A was critical for amplifying such local inflammation, as observed in the production of IL-1ß and neutrophil infiltration following the cross-talk between cancer and host stromal cells. We further determined that γδT cells expressing Vδ1 semi-invariant TCR initiate cancer-promoting inflammation by producing IL-17A in an MyD88/IL-23-dependent manner. Finally, we identified CD30 as a key molecule in the inflammatory function of Vδ1T cells and the blockade of this pathway targeted this cancer immune-escalation process. Collectively, these results reveal the importance of IL-17A-producing CD30(+) Vδ1T cells in triggering inflammation and orchestrating a microenvironment leading to cancer progression.

Cutting Edge: CLEC5A Mediates Macrophage Function and Chronic Obstructive Pulmonary Disease Pathologies.

Chronic obstructive pulmonary disease (COPD) is a devastating disease with no effective therapies. We investigated the role of the C-type lectin receptor, CLEC5A, in macrophage activation and pulmonary pathogenesis in a mouse model of COPD. We demonstrate that CLEC5A is expressed on alveolar macrophages in mice exposed long-term to cigarette smoke (CS), as well as in human smokers. We also show that CLEC5A-mediated activation of macrophages enhanced cytokine elaboration alone, as well as in combination with LPS or GM-CSF in CS-exposed mice. Furthermore, usingClec5a-deficient mice, we demonstrate that CS-induced macrophage responsiveness is mediated by CLEC5A, and CLEC5A is required for the development of inflammation, proinflammatory cytokine expression, and airspace enlargement. These findings suggest a novel mechanism that promotes airway inflammation and pathologies in response to CS exposure and identifies CLEC5A as a novel target for the therapeutic control of COPD pathogenesis.

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.

IL-12 and IL-23 cytokines: from discovery to targeted therapies for immune-mediated inflammatory diseases.

The cytokine interleukin-12 (IL-12) was thought to have a central role in T cell-mediated responses in inflammation for more than a decade after it was first identified. Discovery of the cytokine IL-23, which shares a common p40 subunit with IL-12, prompted efforts to clarify the relative contribution of these two cytokines in immune regulation. Ustekinumab, a therapeutic agent targeting both cytokines, was recently approved to treat psoriasis and psoriatic arthritis, and related agents are in clinical testing for a variety of inflammatory disorders. Here we discuss the therapeutic rationale for targeting these cytokines, the unintended consequences for host defense and tumor surveillance and potential ways in which these therapies can be applied to treat additional immune disorders.

IL-23-mediated mononuclear phagocyte crosstalk protects mice from Citrobacter rodentium-induced colon immunopathology.

Gut homeostasis and mucosal immune defense rely on the differential contributions of dendritic cells (DC) and macrophages. Here we show that colonic CX3CR1(+) mononuclear phagocytes are critical inducers of the innate response to Citrobacter rodentium infection. Specifically, the absence of IL-23 expression in macrophages or CD11b(+) DC results in the impairment of IL-22 production and in acute lethality. Highlighting immunopathology as a death cause, infected animals are rescued by the neutralization of IL-12 or IFNγ. Moreover, mice are also protected when the CD103(+) CD11b(-) DC compartment is rendered deficient for IL-12 production. We show that IL-12 production by colonic CD103(+) CD11b(-) DC is repressed by IL-23. Collectively, in addition to its role in inducing IL-22 production, macrophage-derived or CD103(-) CD11b(+) DC-derived IL-23 is required to negatively control the otherwise deleterious production of IL-12 by CD103(+) CD11b(-) DC. Impairment of this critical mononuclear phagocyte crosstalk results in the generation of IFNγ-producing former TH17 cells and fatal immunopathology.

The IL-23-IL-17 immune axis: from mechanisms to therapeutic testing.

Following the discovery of T helper 17 (TH17) cells, the past decade has witnessed a major revision of the TH subset paradigm and substantial progress has been made in deciphering the molecular mechanisms of T cell lineage commitment and function. In this Review, we focus on the recent advances that have been made regarding the transcriptional control of TH17 cell plasticity and stability, as well as the effector functions of TH17 cells, and we highlight the mechanisms of IL-17 signalling in mesenchymal and barrier epithelial tissues. We also discuss the emerging clinical data showing that IL-17-specific and IL-23-specific antibody treatments are remarkably effective for treating many immune-mediated inflammatory diseases.

Th17 cell development: from the cradle to the grave.

T cells surviving the clonal selection process emigrate from the thymus to the periphery as immature naive T cells. In the periphery, upon activation under specific cytokine milieus, naive T cells adopt specific effector phenotypes, e.g. T-helper 1 (Th1), Th2, or Th17, and acquire diverse functions to control a myriad of pathogens, tissue injuries, and other immunological insults. Interleukin-23 (IL-23) is one of the key cytokines that shapes the development and function of Th17 cells with characteristic expression of retinoic acid receptor-related orphan receptor γ-t (RORγt), IL-17, IL-22, and granulocyte macrophage colony-stimulating factor (GM-CSF). More recently, emerging data suggest that IL-23 also promotes development of 'natural Th17' (nTh17) cells that arise from the thymus, analogous to natural regulatory T cells (nTreg). We are just beginning to understand the unique thymic developmental path of nTh17 cells, which are distinct from antigen-experienced memory Th17 cells. In this review, we explore the differentiation and function of inducible, natural, and memory Th17 subsets, which encompass a broad range of immune functions while maintaining tissue hemostasis, and highlight the participation of IL-23 during the life cycle of Th17 cells.

Epithelial cell-derived IL-25, but not Th17 cell-derived IL-17 or IL-17F, is crucial for murine asthma.

IL-17A, IL-17F, and IL-25 are ligands for IL-17RA. In the current study, we demonstrated that IL-25-deficient mice-but not IL-17A-, IL-17F-, IL-17A/F-, IL-23p19-, or retinoic acid-related orphan receptor (ROR)-γt-deficient mice-showed significant suppression of 1) the number of eosinophils and the levels of proinflammatory mediators in bronchoalveolar lavage fluids, 2) airway hyperresponsiveness to methacholine, and 3) OVA-specific IgG1 and IgE levels in the serum during OVA-induced Th2-type/eosinophilic airway inflammation. The IL-25 deficiency did not affect lung dendritic cell migration or Ag-specific memory-Th2 cell expansion during Ag sensitization. Adoptive transfer of T cells, mast cells, or bone marrow cells from IL-25-deficient mice revealed that induction of Th2-type/eosinophilic airway inflammation was dependent on activation of lung epithelial cells and eosinophils by IL-25 produced by airway structural cells such as epithelial cells but not by such hematopoietic stem-cell-origin immune cells as T cells and mast cells. Therefore, airway structural cell-derived IL-25-rather than Th17 cell-derived IL-17A and IL-17F-is responsible for induction of local inflammation by promoting activation of lung epithelial cells and eosinophils in the elicitation phase of Th2-type/eosinophilic airway inflammation. It is not required for Ag-specific Th2 cell differentiation in the sensitization phase.

The myeloid receptor PILRß mediates the balance of inflammatory responses through regulation of IL-27 production.

Paired immunoglobulin-like receptors beta, PILRß, and alpha, PILRα, are related to the Siglec family of receptors and are expressed primarily on cells of the myeloid lineage. PILRß is a DAP12 binding partner expressed on both human and mouse myeloid cells. The potential ligand, CD99, is found on many cell types, such as epithelial cells where it plays a role in migration of immune cells to sites of inflammation. Pilrb deficient mice were challenged with the parasite Toxoplasma gondii in two different models of infection induced inflammation; one involving the establishment of chronic encephalitis and a second mimicking inflammatory bowel disease in order to understand the potential role of this receptor in persistent inflammatory responses. It was found that in the absence of activating signals from PILRß, antigen-presenting cells (APCs) produced increased amounts of IL-27, p28 and promoted IL-10 production in effector T cells. The sustained production of IL-27 led ultimately to enhanced survival after challenge due to dampened immune pathology in the gut. Similar protection was also observed in the CNS during chronic T. gondii infection after i.p. challenge again providing evidence that PILRß is important for regulating aberrant inflammatory responses.

Activation of MDL-1 (CLEC5A) on immature myeloid cells triggers lethal shock in mice.

Systemic inflammatory response syndrome (SIRS) is a potentially lethal condition, as it can progress to shock, multi-organ failure, and death. It can be triggered by infection, tissue damage, or hemorrhage. The role of tissue injury in the progression from SIRS to shock is incompletely understood. Here, we show that treatment of mice with concanavalin A (ConA) to induce liver injury triggered a G-CSF-dependent hepatic infiltration of CD11b+Gr-1+Ly6G+Ly6C+ immature myeloid cells that expressed the orphan receptor myeloid DAP12-associated lectin-1 (MDL-1; also known as CLEC5A). Activation of MDL-1 using dengue virus or an agonist MDL-1-specific antibody in the ConA-treated mice resulted in shock. The MDL-1+ cells were pathogenic, and in vivo depletion of MDL-1+ cells provided protection. Triggering MDL-1 on these cells induced production of NO and TNF-α, which were found to be elevated in the serum of treated mice and required for MDL-1-induced shock. Surprisingly, MDL-1-induced NO and TNF-α production required eNOS but not iNOS. Activation of DAP12, DAP10, Syk, PI3K, and Akt was critical for MDL-1-induced shock. In addition, Akt physically interacted with and activated eNOS. Therefore, triggering of MDL-1 on immature myeloid cells and production of NO and TNF-α may play a critical role in the pathogenesis of shock. Targeting the MDL-1/Syk/PI3K/Akt/eNOS pathway represents a potential new therapeutic strategy to prevent the progression of SIRS to shock.

Generation of pathogenic T(H)17 cells in the absence of TGF-ß signalling.

CD4(+) T-helper cells that selectively produce interleukin (IL)-17 (T(H)17), are critical for host defence and autoimmunity. Although crucial for T(H)17 cells in vivo, IL-23 has been thought to be incapable of driving initial differentiation. Rather, IL-6 and transforming growth factor (TGF)-ß1 have been proposed to be the factors responsible for initiating specification. Here we show that T(H)17 differentiation can occur in the absence of TGF-ß signalling. Neither IL-6 nor IL-23 alone efficiently generated T(H)17 cells; however, these cytokines in combination with IL-1ß effectively induced IL-17 production in naive precursors, independently of TGF-ß. Epigenetic modification of the Il17a, Il17f and Rorc promoters proceeded without TGF-ß1, allowing the generation of cells that co-expressed RORγt (encoded by Rorc) and T-bet. T-bet(+)RORγt(+) T(H)17 cells are generated in vivo during experimental allergic encephalomyelitis, and adoptively transferred T(H)17 cells generated with IL-23 without TGF-ß1 were pathogenic in this disease model. These data indicate an alternative mode for T(H)17 differentiation. Consistent with genetic data linking IL23R with autoimmunity, our findings re-emphasize the importance of IL-23 and therefore may have therapeutic implications.