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Type I interferon-mediated activation of immune cells can facilitate the generation of productive tumor antigen-specific T cell responses in solid tumors. The cGAS/STING DNA sensing pathway is a critical upstream mediator of type I interferon production and is an important regulator of anti-tumor immunity. Numerous STING pathway agonists are now being tested in clinical trials, but the effectiveness of this approach is not yet clear and a better understanding of the relative importance of this pathway in various tumor settings is needed. We have evaluated syngeneic tumor models with different baseline inflammatory states to determine the contributions of STING activity in both tumor and non-tumor cellular compartments to anti-tumor immune responses. We find that productive anti-tumor immune responses in the poorly immunogenic B16F10 model show a strong dependence on STING expression in non-tumor cells. In the immunogenic MC38 model, constitutive STING activation in tumor cells can partially bypass the requirement for STING-dependent activity from immune cells. Our findings reveal multiple, context-dependent roles for STING activity in the regulation of anti-tumor immunity and the response to immunotherapy. In preclinical models where STING is basally active, checkpoint inhibition is more likely to have a therapeutic effect and removal of STING signaling from either the tumor or the non-tumor compartment has a minimal effect. Removal of STING signaling in both, however, diminishes the efficacy derived from checkpoint therapy. Further work is needed to understand the heterogeneity of STING signaling in patients, both in tumor cells and the tumor microenvironment, and the best means of harnessing this pathway to generate anti-tumor immunity and improve therapeutic outcomes.

BackgroundCheckpoint inhibitors targeting cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) have demonstrated clinical efficacy in advanced melanoma, but only a subset of patients with inflamed tumors are responsive. Talimogene laherparepvec (T-VEC), a modified herpes simplex virus type 1 (HSV-1) expressing granulocyte-macrophage colony-stimulating factor (GM-CSF), is a first-in-class oncolytic immunotherapy approved for the treatment of melanoma and has been shown to inflame the tumor microenvironment. To evaluate the potential and mechanisms of T-VEC to elicit systemic antitumor immunity and overcome resistance to checkpoint inhibitors in murine tumor models, OncoVEXmGM-CSFwas developed similarly to T-VEC, except the human GM-CSF transgene was replaced with murine GM-CSF. Previous work had demonstrated that OncoVEXmGM-CSFgenerated systemic antitumor immunity dependent on CD8+ T cells in an immune checkpoint-sensitive tumor cell model.MethodsA novel B16F10 syngeneic tumor model with both HSV-1−permissive subcutaneous tumors and HSV-1−refractory experimental lung metastasis was used to study the local and systemic effects of OncoVEXmGM-CSFtreatment alone or in combination with checkpoint inhibitors.ResultsIntratumoral injection of OncoVEXmGM-CSFin combination with an anti-CTLA-4 or anti-PD-1 blocking antibody led to increased tumor growth inhibition, a reduction in the number of lung metastases, and prolonged animal survival. OncoVEXmGM-CSFinduced both neoantigen-specific and tumor antigen-specific T-cell responses. Furthermore, cured mice from the combination treatment of OncoVEXmGM-CSFand anti-CTLA-4 antibody rejected tumor rechallenges.ConclusionsThese data support the concept that T-VEC and checkpoint inhibition may be an effective combination to treat patients with advanced melanoma.

Therapeutic approaches are needed to promote T cell-mediated destruction of poorly immunogenic, "cold" tumors typically associated with minimal response to immune checkpoint blockade (ICB) therapy. Bispecific T cell engager (BiTE) molecules induce redirected lysis of cancer cells by polyclonal T cells and have demonstrated promising clinical activity against solid tumors in some patients. However, little is understood about the key factors that govern clinical responses to these therapies. Using an immunocompetent mouse model expressing a humanized CD3e chain (huCD3e mice) and BiTE molecules directed against mouse CD19, mouse CLDN18.2, or human EPCAM antigens, we investigated the pharmacokinetic and pharmacodynamic parameters and immune correlates associated with BiTE efficacy across multiple syngeneic solid-tumor models. These studies demonstrated that pretreatment tumor-associated T cell density is a critical determinant of response to BiTE therapy, identified CD8+ T cells as important targets and mediators of BiTE activity, and revealed an antagonistic role for CD4+ T cells in BiTE efficacy. We also identified therapeutic combinations, including ICB and 4-1BB agonism, that synergized with BiTE treatment in poorly T cell-infiltrated, immunotherapy-refractory tumors. In these models, BiTE efficacy was dependent on local expansion of tumor-associated CD8+ T cells, rather than their recruitment from circulation. Our findings highlight the relative contributions of baseline T cell infiltration, local T cell proliferation, and peripheral T cell trafficking for BiTE molecule-mediated efficacy, identify combination strategies capable of overcoming resistance to BiTE therapy, and have clinical relevance for the development of BiTE and other T cell engager therapies.

Single cell RNAseq analyses were performed on T cells from MC38 and CT26 tumor models. PCA-based sub-clustering and STARTRAC analyses revealed fine-tuned T cell subsets and dynamic in tumor. CCR8 was identified as a novel target on Tregs to synergize with anti–PD-1 for cancer immunotherapy., Single-cell RNA sequencing is a powerful tool to examine cellular heterogeneity, novel markers and target genes, and therapeutic mechanisms in human cancers and animal models. Here, we analyzed single-cell RNA sequencing data of T cells obtained from multiple mouse tumor models by PCA-based subclustering coupled with TCR tracking using the STARTRAC algorithm. This approach revealed various differentiated T cell subsets and activation states, and a correspondence of T cell subsets between human and mouse tumors. STARTRAC analyses demonstrated peripheral T cell subsets that were developmentally connected with tumor-infiltrating CD8+ cells, CD4+ Th1 cells, and T reg cells. In addition, large amounts of paired TCRα/β sequences enabled us to identify a specific enrichment of paired public TCR clones in tumor. Finally, we identified CCR8 as a tumor-associated T reg cell marker that could preferentially deplete tumor-associated T reg cells. We showed that CCR8-depleting antibody treatment provided therapeutic benefit in CT26 tumors and synergized with anti–PD-1 treatment in MC38 and B16F10 tumor models., Graphical Abstract

BackgroundRecent advances in the field of cancer immunotherapy have identified CD8+ T cell responses against tumor-specific mutations as a key driver of tumor regression and overall survival. ADXS-NEO is a personalized Listeria monocytogenes (Lm)-based immunotherapy designed to target a patient’s mutation-derived tumor-specific neoantigens. The objective of this study is to demonstrate the feasibility of using the ADXS-NEO platform to target tumor-specific point mutations and control tumor growth by generating neoantigen-specific T cell responses using a pre-clinical mouse tumor model.MethodsWhole-exome sequencing of the MC38 mouse tumor cell line identified 2870 unique non-synonymous mutations. The netMHCcons algorithm was used to predict 137 potential neoantigens. We validated 20 immunogenic neoantigens either by peptide immunization followed by ELISPOT or by the presence of CD8+ T cells recognizing the neoantigen peptide following checkpoint inhibitor treatment. Two ADXS-NEO vectors were constructed; Lm20, targeting 20 validated immunogenic neoantigens, and Lm19, targeting most of the non-validated NSMs.ResultsBoth Lm19 & Lm20 significantly slowed tumor growth in C57BL/6 mice compared to control. An accumulation of ADXS-NEO-specific TILs was observed in tumor bearing mice treated with either Lm19 or Lm20. Examination of the tumor microenvironment in Lm19 or Lm20 treated mice revealed a decrease in the frequency and absolute number of Tregs, TAMs, MDSCs, and PD1high exhausted CD8+ T cells as well as an increase in the frequency and absolute number of effector CD8+ T cells, relative to control.ConclusionADXS-NEO is a potent immunotherapy capable of driving immune responses against tumor-specific mutations and leading to tumor control in mice.

Inhibitors that block the programmed cell death-1 (PD-1) pathway can potentiate endogenous antitumor immunity and have markedly improved cancer survival rates across a broad range of indications. However, these treatments work for only a minority of patients. The efficacy of anti-PD-1 inhibitors may be extended by cytokines, however, the incorporation of cytokines into therapeutic regimens has significant challenges. In their natural form when administered as recombinant proteins, cytokine treatments are often associated with low response rates. Most cytokines have a short half-life which limits their exposure and efficacy. In addition, cytokines can activate counterregulatory pathways, in the case of immune-potentiating cytokines this can lead to immune suppression and thereby diminish their potential efficacy. Improving the drug-like properties of natural cytokines using protein engineering can yield synthetic cytokines with improved bioavailability and tissue targeting, allowing for enhanced efficacy and reduced off-target effects. Using structure guided engineering we have designed a novel class of antibody-cytokine fusion proteins consisting of a PD-1 targeting antibody fused together with an interleukin-21 (IL-21) cytokine mutein. Our bifunctional fusion proteins can block PD-1/programmed death-ligand 1 (PD-L1) interaction whilst simultaneously delivering IL-21 cytokine to PD-1 expressing T cells. Targeted delivery of IL-21 can improve T cell function in a manner that is superior to anti-PD-1 monotherapy. Fusion of engineered IL-21 variants to anti-PD1 antibodies can improve the drug-like properties of IL-21 cytokine leading to improved cytokine serum half-life allowing for less frequent dosing. In addition, we show that targeted delivery of IL-21 can minimize any potential detrimental effect on local antigen-presenting cells. A highly attenuated IL-21 mutein variant (R9E:R76A) fused to a PD-1 antibody provides protection in a humanized mouse model of cancer that is refractory to anti-PD-1 monotherapy. Collectively, our preclinical data demonstrate that this approach may improve upon and extend the utility of anti-PD-1 therapeutics currently in the clinic.

Bone marrow chimeras represent a key tool employed to understand biological contributions stemming from the hematopoietic versus the stromal compartment. In most institutions, cesium irradiators are used to lethally irradiate recipient animals prior to the injection of donor bone marrow. Cesium irradiators, however, have significant liabilities—including concerns around domestic security. Recently, X-ray irradiators have been implemented as a potential alternative to cesium sources. Only a small number of publications in the literature have attempted to compare these two modalities and, in most cases, the emphasis was on irradiation of human blood productions. We were able to find only a single study that directly compared X-ray and cesium technologies in the generation of murine bone marrow chimeras, a standard laboratory practice. This study focused on chimerism in the blood of recipient animals. In the present study, we begin by comparing cesium and X-ray based sources for irradiation, then transition to using X-ray-based systems for immunology models with an emphasis on immunotherapy of cancer in immunocompetent mouse models—specifically evaluating chimerism in the blood, spleen, and tumor microenvironment. While our data demonstrate that the two platforms are functionally comparable and suggest that X-ray based technology is a suitable alternative to cesium sources. We also highlight a difference in chimerism between the peripheral (blood, spleen) and tumor compartments that is observed using both technologies. While the overall degree of chimerism in the peripheral tissues is very high, the degree of chimerism in the tumor is cell type specific with T and NK cells showing lower chimerism than other cell types.

NF-κB-inducing kinase (NIK) mediates non-canonical NF-κB signaling downstream of multiple TNF family members, including BAFF, TWEAK, CD40, and OX40, which are implicated in the pathogenesis of systemic lupus erythematosus (SLE). Here, we show that experimental lupus in NZB/W F1 mice can be treated with a highly selective and potent NIK small molecule inhibitor. Both in vitro as well as in vivo, NIK inhibition recapitulates the pharmacological effects of BAFF blockade, which is clinically efficacious in SLE. Furthermore, NIK inhibition also affects T cell parameters in the spleen and proinflammatory gene expression in the kidney, which may be attributable to inhibition of OX40 and TWEAK signaling, respectively. As a consequence, NIK inhibition results in improved survival, reduced renal pathology, and lower proteinuria scores. Collectively, our data suggest that NIK inhibition is a potential therapeutic approach for SLE., Clinical trials of BAFF blockade with belimumab have shown partial efficacy for the treatment of systemic lupus erythematosus (SLE), so other therapeutic options are required. Here, the authors present a new small molecule inhibitor that targets NIK with a similar efficacy to BAFF inhibition in two mouse models of SLE.

Oncolytic virotherapy is an emerging treatment modality that may hold promise as a therapeutic option for cancer patients who do not respond to checkpoint inhibitors. Oncolytic viruses preferentially replicate in tumor cells, offer the ability to express transgenes and have been shown to modify the local and distant tumor microenvironments from immunosuppressive to immunostimulatory. We generated HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12, an oncolytic virus based on a modified herpes simplex virus type 1 (HSV-1) designed to selectively replicate in tumors and produce murine FMS-like tyrosine kinase 3 ligand (mFLT3L) to enhance dendritic cell expansion and T cell priming, and murine interleukin-12 (mIL12) to potentiate type I helper and cytotoxic T cell responses. We confirmed the expression and bioactivity of mFLT3L and mIL12 in vitro and evaluated the efficacy of HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 alone and in combination with anti-PD-1 or anti-4-1BB treatment in multiple syngeneic mouse tumor models. Bilateral tumor models were used and only one tumor was treated via intratumoral injection with HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12. Anti-tumor responses were evaluated in the injected tumor (local response), the uninjected tumor (abscopal) and via splenic immune profiling (systemic). HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 treatment alone led to tumor growth inhibition in both treated and contralateral tumors, and a significant increase in overall survival in the A20, Neuro2a and MC38 models. HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 in combination with anti-PD-1 blocking antibody further improved tumor growth inhibition in both treated and contralateral tumors in the MC38 syngeneic model, and significantly increased median overall survival compared to either agent as a monotherapy. In addition, HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 in combination with an agonistic antibody targeting 4-1BB significantly increased overall survival compared to either agent as a monotherapy in the MC38 model. To understand antigen-specific anti-tumor T cell responses, MC38 tumor antigen epitopes were identified by combining exome sequencing and MHC/HLA-binding prediction algorithms. Antigen-specific T cell responses were measured in an IFN-γ ELISPOT assay using splenocytes from treated mice. HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 induced and/or enhanced systemic T cell responses directed against both tumor neoantigens and tumor-associated antigens. Together, these data reveal that treatment with HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 can cause direct tumor lysis and induce an adaptive, systemic T cell-mediated anti-tumor immune response that can be further enhanced by concurrent PD-1 blockade or 4-1BB agonism in multiple syngeneic mouse tumor models. Citation Format: Keegan Cooke, Walter H. Meisen, Petia Mitchell, Juan Estrada, Jinghui Zhan, Jessica Orf, Peng Li, Christina de Zafra, Jing Qing, Jason DeVoss. Oncolytic virus HSV-1/ICP34.5-/ICP47-/mFLT3L/mIL12 promotes systemic anti-tumor responses and cooperates with immuno-modulatory agents in multiple mouse syngeneic tumor models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1586.

Colony-stimulating factor 1 (CSF1) and interleukin 34 (IL34) signal via the CSF1 receptor to regulate macrophage differentiation. Studies in IL34- or CSF1-deficient mice have revealed that IL34 function is limited to the central nervous system and skin during development. However, the roles of IL34 and CSF1 at homeostasis or in the context of inflammatory diseases or cancer in wild-type mice have not been clarified in vivo. By neutralizing CSF1 and/or IL34 in adult mice, we identified that they play important roles in macrophage differentiation, specifically in steady-state microglia, Langerhans cells, and kidney macrophages. In several inflammatory models, neutralization of both CSF1 and IL34 contributed to maximal disease protection. However, in a myeloid cell-rich tumor model, CSF1 but not IL34 was required for tumor-associated macrophage accumulation and immune homeostasis. Analysis of human inflammatory conditions reveals IL34 upregulation that may account for the protection requirement of IL34 blockade. Furthermore, evaluation of IL34 and CSF1 blockade treatment during Listeria infection reveals no substantial safety concerns. Thus, IL34 and CSF1 play non-redundant roles in macrophage differentiation, and therapeutic intervention targeting IL34 and/or CSF1 may provide an effective treatment in macrophage-driven immune-pathologies.

IL-17 has been implicated in the pathogenesis of multiple sclerosis (MS). Here, we show that blockade of IL-17A, but not IL-17F, attenuated experimental autoimmune encephalomyelitis (EAE). We further show that IL-17A levels were elevated in the CSF of relapsing-remitting MS (RRMS) patients and that they correlated with the CSF/serum albumin quotient (Qalb), a measure of blood-brain barrier (BBB) dysfunction. We then demonstrated that the combination of IL-17A and IL-6 reduced the expression of tight junction (TJ)-associated genes and disrupted monolayer integrity in the BBB cell line hCMEC/D3. However, unlike IL-17A, IL-6 in the CSF from RRMS patients did not correlate with Qalb. These data highlight the potential importance of targeting IL-17A in preserving BBB integrity in RRMS.

Necroptosis is a caspase-independent form of cell death that is triggered by activation of the receptor interacting serine/threonine kinase 3 (RIPK3) and phosphorylation of its pseudokinase substrate mixed lineage kinase-like (MLKL), which then translocates to membranes and promotes cell lysis. Activation of RIPK3 is regulated by the kinase RIPK1. Here we analyze the contribution of RIPK1, RIPK3, or MLKL to several mouse disease models. Loss of RIPK3 had no effect on lipopolysaccharide-induced sepsis, dextran sodium sulfate-induced colitis, cerulein-induced pancreatitis, hypoxia-induced cerebral edema, or the major cerebral artery occlusion stroke model. However, kidney ischemia-reperfusion injury, myocardial infarction, and systemic inflammation associated with A20 deficiency or high-dose tumor necrosis factor (TNF) were ameliorated by RIPK3 deficiency. Catalytically inactive RIPK1 was also beneficial in the kidney ischemia-reperfusion injury model, the high-dose TNF model, and in A20(-/-) mice. Interestingly, MLKL deficiency offered less protection in the kidney ischemia-reperfusion injury model and no benefit in A20(-/-) mice, consistent with necroptosis-independent functions for RIPK1 and RIPK3. Combined loss of RIPK3 (or MLKL) and caspase-8 largely prevented the cytokine storm, hypothermia, and morbidity induced by TNF, suggesting that the triggering event in this model is a combination of apoptosis and necroptosis. Tissue-specific RIPK3 deletion identified intestinal epithelial cells as the major target organ. Together these data emphasize that MLKL deficiency rather than RIPK1 inactivation or RIPK3 deficiency must be examined to implicate a role for necroptosis in disease.

The development and success of Blincyto®, a Bi-Specific T cell Engager (BiTE®), to treat acute lymphoblastic leukemia has expanded the class of anticancer immunotherapy agents. BiTE® molecules consist of a single-chain Fc antibody containing tandem single-chain variable fragments (scFv) recognizing the CD3 receptor on T lymphocytes and a tumor-associated antigen and induce redirected T-cell cytotoxicity and tumor cell lysis. Despite the clinically validated efficacy of BiTE® molecules, there has been little elucidation of the parameters governing their in vivo activity. This is due, in part, to a lack of immunocompetent murine tumor models that allow for engagement of endogenous T cells in the context of an intact immune system, which more accurately mimic the human therapeutic setting. We have developed a genetically engineered mouse model (huCD3 mouse) in which a human/mouse chimeric CD3ϵ receptor recognized by BiTE® molecules was engineered into the mouse CD3ϵ genomic locus. Here, we characterize the immune cell distribution of the huCD3 mouse and utilize BiTE® molecules and syngeneic tumor models to elucidate pharmacokinetic, pharmacodynamic, and efficacy relationships in vivo. The peripheral B and T cell distribution profile of huCD3 mice and WT littermates are comparable, but T cells isolated from huCD3 mice express lower levels of. In T cell-dependent cytotoxic (TDCC) assays, an anti-huEpCAM BiTE® molecule exhibited similar potency against MC38 mouse cells expressing human EpCAM co-cultured with T cells from the huCD3 mice or a human donor, if mouse T-cells were preactivated in vitro. In vivo, MC38-huEpCAM tumors grew robustly and anti-huEpCAM BiTEÂ treatment resulted in dose-dependent tumor growth inhibition, with several tumor-free animals at higher doses. Flow cytometry analysis of disaggregated tumors and serum cytokine analysis indicated that BiTE® treatment resulted in T-cell activation and a cytokine response at doses that correlate with tumor regression. In vivo studies were also performed using B16F10-huEPCAM cells, which generate tumors with reduced T-cell infiltration compared to MC38-huEpCAM. Additionally, we used WT mice reconstituted with different ratios of huCD3e and WT bone marrow to investigate the T-cell number requirement for optimal BiTE®-mediated efficacy. We also evaluated the efficacy of an anti-mouse CD19 BiTE® molecule against MC38-CD19 tumor cells to compare the requirements for antitumor efficacy versus normal B-cell depletion in the blood and in lymphoid organs. Finally, we performed a rational combination study using BiTE® molecules and a PD1 inhibitor, demonstrating that this combination can lead to the eradication of poorly T cell-infiltrated solid tumors. These data begin to elucidate the in vivo mechanisms regulating the efficacy of BiTE® molecules under physiologically relevant conditions. This abstract is also being presented as Poster A29. Citation Format: Brian Belmontes, Hong Tan, Wendy Zhong, Danny Chui, Kevin Cook, Sarah O'Brien, Melissa Martin, Brandy Alexander, Jason Eng, John Harrold, Famke Aeffner, Matthew Chun, Alice Bakker, Mercedesz Balazs, Jason DeVoss, Angela Coxon, Jude Canon, Jackson Egen, Olivier Nolan-Stevaux. Assessing in vivo mechanisms regulating the therapeutic activity of bi-specific T-cell engager (BiTE®) molecules in immunocompetent mice expressing a chimeric human/mouse CD3ϵ receptor [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr PR12.

Retinoic acid receptor-related orphan receptor C (RORc, RORγ, or NR1F3) is a nuclear receptor that plays a major role in the production of interleukin (IL)-17. Considerable efforts have been directed toward the discovery of selective RORc inverse agonists as potential treatments of inflammatory diseases such as psoriasis and rheumatoid arthritis. Using the previously reported tertiary sulfonamide 1 as a starting point, we engineered structural modifications that significantly improved human and rat metabolic stabilities while maintaining a potent and highly selective RORc inverse agonist profile. The most advanced δ-sultam compound, GNE-3500 (27, 1-{4-[3-fluoro-4-((3S,6R)-3-methyl-1,1-dioxo-6-phenyl-[1,2]thiazinan-2-ylmethyl)-phenyl]-piperazin-1-yl}-ethanone), possessed favorable RORc cellular potency with 75-fold selectivity for RORc over other ROR family members and >200-fold selectivity over 25 additional nuclear receptors in a cell assay panel. The favorable potency, selectivity, in vitro ADME properties, in vivo PK, and dose-dependent inhibition of IL-17 in a PK/PD model support the evaluation of 27 in preclinical studies.

B7-H4 has been implicated in cancers of the female reproductive system and investigated for its possible use as a biomarker for cancer, but there are no preclinical studies to demonstrate that B7-H4 is a molecular target for therapeutic intervention of cancer. We provide evidence that the prevalence and expression levels of B7-H4 are high in different subtypes of breast cancer and that only a few normal tissues express B7-H4 on the cell membrane. These profiles of low normal expression and upregulation in cancer provide an opportunity for the use of antibody-drug conjugates (ADCs), cytotoxic drugs chemically linked to antibodies, for the treatment of B7-H4 positive cancers. We have developed an ADC specific to B7-H4 that uses a linker drug consisting of a potent antimitotic, monomethyl auristatin E (MMAE), linked to engineered cysteines (THIOMAB) via a protease labile linker. We will refer to ADCs that use the THIOMAB format as TDCs to help distinguish the format from standard MC-vc-MMAE ADCs that are conjugated to the interchain disulfide bonds. Anti-B7-H4 (h1D11)-MC-vc-PAB-MMAE (h1D11 TDC) produced durable tumor regression in cell line and patient-derived xenograft models of triple-negative breast cancer. It also binds rat B7-H4 with similar affinity to human and allowed us to test for target dependent toxicity in rats. We found that our anti-B7-H4 TDC has toxicity findings similar to untargeted TDC. Our results validate B7-H4 as an ADC target for breast cancer and support the possible use of this TDC in the treatment of B7-H4(+) breast cancer.

Mouse models of inflammatory bowel disease are critical for basic and translational research that is advancing the understanding and treatment of this disease. Assessment of these mouse models frequently relies on histologic endpoints. In recent years, whole slide imaging and digital pathology-based image analysis platforms have become increasingly available for implementation into the pathology workflow. These automated image analysis approaches allow for nonbiased quantitative assessment of histologic endpoints. In this study, the authors sought to develop an image analysis workflow using a commercially available image analysis platform that requires minimal training in image analysis or programming, and this workflow was used to score 2 mouse models of colitis that are primarily characterized by immune cell infiltrates in the lamina propria. Although the software was unable to accurately and consistently segment hematoxylin and eosin–stained sections, automated quantification of CD3 immunolabeling resulted in strong correlations with the pathologist’s score in all studies and allowed for the identification of 8 of the 9 differences among treatment groups that were identified by the pathologist. These results demonstrate not only the ability to incorporate solutions based on image analysis into the pathologist’s workflow but also the importance of immunohistochemical or histochemical surrogates for the incorporation of image analysis in histologic assessments.

T-helper type 17 (TH17) cells that produce the cytokines interleukin-17A (IL-17A) and IL-17F are implicated in the pathogenesis of several autoimmune diseases. The differentiation of TH17 cells is regulated by transcription factors such as RORγt, but post-translational mechanisms preventing the rampant production of pro-inflammatory IL-17A have received less attention. Here we show that the deubiquitylating enzyme DUBA is a negative regulator of IL-17A production in T cells. Mice with DUBA-deficient T cells developed exacerbated inflammation in the small intestine after challenge with anti-CD3 antibodies. DUBA interacted with the ubiquitin ligase UBR5, which suppressed DUBA abundance in naive T cells. DUBA accumulated in activated T cells and stabilized UBR5, which then ubiquitylated RORγt in response to TGF-β signalling. Our data identify DUBA as a cell-intrinsic suppressor of IL-17 production.

Herein we report identification of an imidazopyridine class of potent and selective TYK2 inhibitors, exemplified by prototype 6, through constraint of the rotatable amide bond connecting the pyridine and aryl rings of compound 1. Further optimization led to generation of compound 30 that potently inhibits the TYK2 enzyme and the IL-23 pathway in cells, exhibits selectivity against cellular JAK2 activity, and has good pharmacokinetic properties. In mice, compound 30 demonstrated dose-dependent reduction of IL-17 production in a PK/PD model as well as in an imiquimod-induced psoriasis model. In this efficacy model, the IL-17 decrease was accompanied by a reduction of ear thickness indicating the potential of TYK2 inhibition as a therapeutic approach for psoriasis patients.

Tumor progression locus 2 (TPL2; also known as MAP3K8) is a mitogen-activated protein kinase (MAPK) kinase kinase (MAP3K) that phosphorylates the MAPK kinases MEK1 and MEK2 (MEK1/2), which, in turn, activate the MAPKs extracellular signal-regulated kinase 1 (ERK1) and ERK2 (ERK1/2) in macrophages stimulated through the interleukin-1 receptor (IL-1R), Toll-like receptors (TLRs), or the tumor necrosis factor receptor (TNFR). We describe a conserved and critical role for TPL2 in mediating the effector functions of neutrophils through the activation of the p38 MAPK signaling pathway. Gene expression profiling and functional studies of neutrophils and monocytes revealed a MEK1/2-independent branch point downstream of TPL2 in neutrophils. Biochemical analyses identified the MAPK kinases MEK3 and MEK6 and the MAPKs p38α and p38δ as downstream effectors of TPL2 in these cells. Genetic ablation of the catalytic activity of TPL2 or therapeutic intervention with a TPL2-specific inhibitor reduced the production of inflammatory mediators by neutrophils in response to stimulation with the TLR4 agonist lipopolysaccharide (LPS) in vitro, as well as in rodent models of inflammatory disease. Together, these data suggest that TPL2 is a drug target that activates not only MEK1/2-dependent but also MEK3/6-dependent signaling to promote inflammatory responses.

Systemic lupus erythematosus (SLE) is often associated with exaggerated B cell activation promoting plasma cell generation, immune-complex deposition in the kidney, renal infiltration of myeloid cells, and glomerular nephritis. Type-I IFNs amplify these autoimmune processes and promote severe disease. Bruton's tyrosine kinase (Btk) inhibitors are considered novel therapies for SLE. We describe the characterization of a highly selective reversible Btk inhibitor, G-744. G-744 is efficacious, and superior to blocking BAFF and Syk, in ameliorating severe lupus nephritis in both spontaneous and IFNα-accelerated lupus in NZB/W_F1 mice in therapeutic regimens. Selective Btk inhibition ablated plasmablast generation, reduced autoantibodies, and - similar to cyclophosphamide - improved renal pathology in IFNα-accelerated lupus. Employing global transcriptional profiling of spleen and kidney coupled with cross-species human modular repertoire analyses, we identify similarities in the inflammatory process between mice and humans, and we demonstrate that G-744 reduced gene expression signatures essential for splenic B cell terminal differentiation, particularly the secretory pathway, as well as renal transcriptional profiles coupled with myeloid cell-mediated pathology and glomerular plus tubulointerstitial disease in human glomerulonephritis patients. These findings reveal the mechanism through which a selective Btk inhibitor blocks murine autoimmune kidney disease, highlighting pathway activity that may translate to human SLE.

The leucine-rich repeat protein NRROS which resides in the endoplasmic reticulum regulates phagocytic NADPH oxidase, minimizing collateral tissue damage caused by reactive oxygen species during inflammatory processes.

Naik et al. show that the deubiquitinating enzyme Usp9X is a regulator of T cell activation and its loss induces the development of a lupuslike autoimmune disease in mice., The T cell hyperproliferation and autoimmune phenotypes that manifest in mice lacking E3 ubiquitin ligases such as Cbl, ITCH, or GRAIL highlight the importance of ubiquitination for the maintenance of peripheral T cell tolerance. Less is known, however, about the deubiquitinating enzymes that regulate T cell proliferation and effector function. Here, we define a cell intrinsic role for the deubiquitinase Usp9X during proximal TCR signaling. Usp9X-deficient T cells were hypoproliferative, yet mice with T cell–specific Usp9x deletion had elevated numbers of antigen-experienced T cells and expanded PD-1 and OX40-expressing populations consistent with immune hyperactivity. Aged Usp9x KO mice developed lupus-like autoimmunity and lymphoproliferative disease, indicating that ubiquitin ligases and deubiquitinases maintain the delicate balance between effective immunity and self-tolerance.

CD11b(+) dendritic cells (DCs) seem to be specialized for presenting antigens via major histocompatibility (MHC) class II complexes to stimulate helper T cells, but the genetic and regulatory basis for this is not established. Conditional deletion of Irf4 resulted in loss of CD11b(+) DCs, impaired formation of peptide-MHC class II complexes and defective priming of helper T cells but not of cytotoxic T lymphocyte (CTL) responses. Gene expression and chromatin immunoprecipitation followed by deep sequencing (ChIP-Seq) analyses delineated an IRF4-dependent regulatory module that programs enhanced MHC class II antigen presentation. Expression of the transcription factor IRF4 but not of IRF8 restored the ability of IRF4-deficient DCs to efficiently process and present antigen to MHC class II-restricted T cells and promote helper T cell responses. We propose that the evolutionary divergence of IRF4 and IRF8 facilitated the specialization of DC subsets for distinct modes of antigen presentation and priming of helper T cell versus CTL responses.

Animal models of human disease are a critical tool in both basic research and drug development. The results of preclinical efficacy studies often inform progression of therapeutic candidates through the drug development pipeline; however, the extent to which results in inflammatory bowel disease (IBD) models predict human drug response is an ongoing concern. This review discusses how murine models are currently being used in IBD research. We focus on the considerations and caveats for commonly used models in preclinical efficacy studies and discuss the value of models that utilize specific pathogenic pathways of interest rather than model all aspects of human disease.

Herein we report our lead optimization effort to identify potent, selective, and orally bioavailable TYK2 inhibitors, starting with lead molecule 3. We used structure-based design to discover 2,6-dichloro-4-cyanophenyl and (1R,2R)-2-fluorocyclopropylamide modifications, each of which exhibited improved TYK2 potency and JAK1 and JAK2 selectivity relative to 3. Further optimization eventually led to compound 37 that showed good TYK2 enzyme and interleukin-12 (IL-12) cell potency, as well as acceptable cellular JAK1 and JAK2 selectivity and excellent oral exposure in mice. When tested in a mouse IL-12 PK/PD model, compound 37 showed statistically significant knockdown of cytokine interferon-γ (IFNγ), suggesting that selective inhibition of TYK2 kinase activity might be sufficient to block the IL-12 pathway in vivo.

Summary The DSS (dextran sulfate sodium) model of colitis is a mouse model of inflammatory bowel disease. Microscopic symptoms include loss of crypt cells from the gut lining and infiltration of inflammatory cells into the colon. An experienced pathologist requires several hours per study to score histological changes in selected regions of the mouse gut. In order to increase the efficiency of scoring, Definiens Developer software was used to devise an entirely automated method to quantify histological changes in the whole H&E slide. When the algorithm was applied to slides from historical drug-discovery studies, automated scores classified 88% of drug candidates in the same way as pathologists' scores. In addition, another automated image analysis method was developed to quantify colon-infiltrating macrophages, neutrophils, B cells and T cells in immunohistochemical stains of serial sections of the H&E slides. The timing of neutrophil and macrophage infiltration had the highest correlation to pathological changes, whereas T and B cell infiltration occurred later. Thus, automated image analysis enables quantitative comparisons between tissue morphology changes and cell-infiltration dynamics.

Multiple Sclerosis (MS) is a neurodegenerative autoimmune disorder caused by chronic inflammation and demyelination within the central nervous system (CNS). Clinical studies in MS patients have demonstrated efficacy with B cell targeted therapies such as anti-CD20. However, the exact role that B cells play in the disease process is unclear. Activation Induced cytidine deaminase (AID) is an essential enzyme for the processes of antibody affinity maturation and isotype switching. To evaluate the impact of affinity maturation and isotype switching, we have interrogated the effect of AID-deficiency in an animal model of MS. Here, we show that the severity of experimental autoimmune encephalomyelitis (EAE) induced by the extracellular domain of human myelin oligodendrocyte glycoprotein (MOG1-125) is significantly reduced in Aicda deficient mice, which, unlike wild-type mice, lack serum IgG to myelin associated antigens. MOG specific T cell responses are comparable between wild-type and Aicda knockout mice suggesting an active role for antigen experienced B cells. Thus affinity maturation and/or class switching are critical processes in the pathogenesis of EAE.

Loss of function of the nuclear deubiquitinating enzyme BRCA1-associated protein-1 (BAP1) is associated with a wide spectrum of cancers. We report that tamoxifen-induced BAP1 deletion in adult mice resulted in severe thymic atrophy. BAP1 was critical for T cell development at several stages. In the thymus, BAP1 was required for progression through the pre-T cell receptor checkpoint. Peripheral T cells lacking BAP1 demonstrated a defect in homeostatic and antigen-driven expansion. Deletion of BAP1 resulted in suppression of E2F target genes and defects in cell cycle progression, which was dependent on the catalytic activity of BAP1, but did not require its interaction with host cell factor-1 (HCF-1). Loss of BAP1 led to increased monoubiquitination of histone H2A at Lys119 (H2AK119ub) throughout the T cell lineage, in particular in immature thymocytes, but did not alter trimethylation of histone H3 at Lys27 (H3K27me3). Deletion of BAP1 also abrogated B cell development in the bone marrow. Our findings uncover a nonredundant function for BAP1 in maintaining the lymphoid lineage.

SummaryWe introduce neutron-encoded (NeuCode) amino acid labeling of mice as a strategy for multiplexed proteomic analysis in vivo. Using NeuCode, we characterize an inducible knockout mouse model of Bap1, a tumor suppressor and deubiquitinase whose in vivo roles outside of cancer are not well established. NeuCode proteomics revealed altered metabolic pathways following Bap1 deletion, including profound elevation of cholesterol biosynthetic machinery coincident with reduced expression of gluconeogenic and lipid homeostasis proteins in liver. Bap1 loss increased pancreatitis biomarkers and reduced expression of mitochondrial proteins. These alterations accompany a metabolic remodeling with hypoglycemia, hypercholesterolemia, hepatic lipid loss, and acinar cell degeneration. Liver-specific Bap1 null mice present with fully penetrant perinatal lethality, severe hypoglycemia, and hepatic lipid deficiency. This work reveals Bap1 as a metabolic regulator in liver and pancreas, and it establishes NeuCode as a reliable proteomic method for deciphering in vivo biology.

Chronic inflammatory demyelinating polyneuropathy is a debilitating autoimmune disease characterized by peripheral nerve demyelination and dysfunction. How the autoimmune response is initiated, identity of provoking Ags, and pathogenic effector mechanisms are not well defined. The autoimmune regulator (Aire) plays a critical role in central tolerance by promoting thymic expression of self-Ags and deletion of self-reactive T cells. In this study, we used mice with hypomorphic Aire function and two patients with Aire mutations to define how Aire deficiency results in spontaneous autoimmune peripheral neuropathy. Autoimmunity against peripheral nerves in both mice and humans targets myelin protein zero, an Ag for which expression is Aire-regulated in the thymus. Consistent with a defect in thymic tolerance, CD4+ T cells are sufficient to transfer disease in mice and produce IFN-γ in infiltrated peripheral nerves. Our findings suggest that defective Aire-mediated central tolerance to myelin protein zero initiates an autoimmune Th1 effector response toward peripheral nerves.

Dendritic cells promote either immunosuppressive or immunogenic T cell responses, but the transcriptional and epigenetic programs regulating these functions are unclear. Vander Lugt et al. dissect the distinct programs underlying the immunogenic and tolerogenic mature states of dendritic cells in vitro., Dendritic cells (DCs) promote either tolerogenic or immunogenic T cell responses, the latter upon sensing microbes. Using an in vitro system, we analyzed transcriptional determinants that enable mature DCs to direct these opposing T cell outcomes. In the absence of microbial products, the transcription factor interferon regulatory factor 4 (IRF4) promotes regulatory T cell (Treg) generation by enhancing expression of genes required for antigen presentation along with those for T cell tolerance. IRF4-deficient DCs were impaired for Treg generation in vivo. When exposed to microbial stimuli, DCs activated nuclear factor (NF)-κB, which induced expression of a proinflammatory cytokine module that, along with the antigen presentation module, promoted the generation of effector T cells. NF-κB was, however, dispensable for Treg development. Chromatin profiling revealed transcriptional motifs associated with the divergent DC programs. Thus, DCs modulate their ability to prime tolerogenic or immunogenic T cells by expressing a core antigen presentation module that is overlaid by distinctive regulatory modules to promote either tolerance or immunity.

Interleukin-2 (IL-2)-inducible T cell kinase (ITK) mediates T cell receptor (TCR) signaling primarily to stimulate the production of cytokines, such as IL-4, IL-5, and IL-13, from T helper 2 (TH2) cells. Compared to wild-type mice, ITK knockout mice are resistant to asthma and exhibit reduced lung inflammation and decreased amounts of TH2-type cytokines in the bronchoalveolar lavage fluid. We found that a small-molecule selective inhibitor of ITK blocked TCR-mediated signaling in cultured TH2 cells, including the tyrosine phosphorylation of phospholipase C-γ1 (PLC-γ1) and the secretion of IL-2 and TH2-type cytokines. Unexpectedly, inhibition of the kinase activity of ITK during or after antigen rechallenge in an ovalbumin-induced mouse model of asthma failed to reduce airway hyperresponsiveness and inflammation. Rather, in mice, pharmacological inhibition of ITK resulted in T cell hyperplasia and the increased production of TH2-type cytokines. Thus, our studies predict that inhibition of the kinase activity of ITK may not be therapeutic in patients with asthma.

Inactivation of the TNFAIP3 gene, encoding the A20 protein, is associated with critical inflammatory diseases including multiple sclerosis, rheumatoid arthritis and Crohn's disease. However, the role of A20 in attenuating inflammatory signalling is unclear owing to paradoxical in vitro and in vivo findings. Here we utilize genetically engineered mice bearing mutations in the A20 ovarian tumour (OTU)-type deubiquitinase domain or in the zinc finger-4 (ZnF4) ubiquitin-binding motif to investigate these discrepancies. We find that phosphorylation of A20 promotes cleavage of Lys63-linked polyubiquitin chains by the OTU domain and enhances ZnF4-mediated substrate ubiquitination. Additionally, levels of linear ubiquitination dictate whether A20-deficient cells die in response to tumour necrosis factor. Mechanistically, linear ubiquitin chains preserve the architecture of the TNFR1 signalling complex by blocking A20-mediated disassembly of Lys63-linked polyubiquitin scaffolds. Collectively, our studies reveal molecular mechanisms whereby A20 deubiquitinase activity and ubiquitin binding, linear ubiquitination, and cellular kinases cooperate to regulate inflammation and cell death.

Engagement of T cell receptors induces actin rearrangements, which are critical for T cell activation. T cell responses require new actin polymerization, but the significance of higher order actin structures, such as microfilament bundles, is unknown. To determine the role of the actin-bundling protein leukocyte-plastin (L-plastin; LPL) in this process, T cells from LPL−/− mice were studied. LPL−/− T cells were markedly defective in TCR-mediated cytokine production and proliferation. LPL−/− T cells also spread inefficiently on surface with immobilized TCR ligands and formed smaller immunological synapses with APCs, likely due to defective formation of lamellipodia. LPL−/− mice showed delayed rejection of skin allografts after release from immunosuppression. Moreover, LPL−/− mice developed much less severe neurological symptoms in experimental autoimmune encephalomyelitis, which correlated with impaired T cell responses to antigen, manifested by reduced proliferation and production of IFN-γ and IL-17. Thus, LPL-dependent actin bundling facilitates the formation of lamellipodia and normal immunological synapses, and thereby enables T cell activation. This is an author-produced version of a manuscript accepted for publication in The Journal of Immunology (The JI). The American Association of Immunologists, Inc. (AAI), publisher of The JI, holds the copyright to this manuscript. This version of the manuscript has not yet been copyedited or subjected to editorial proofreading by The JI; hence, it may differ from the final version published in The JI (online and in print). AAI (The JI) is not liable for errors or omissions in this author-produced version of the manuscript or in any version derived from it by the U.S. National Institutes of Health or any other third party. The final, citable version of record can be found at www.jimmunol.org.

Introduction: Recent advances in the field of cancer immunotherapy have identified CD8+ T cell responses against tumor-specific neoantigens as a key driver of tumor regression and prolonged survival. ADXS-NEO is a personalized Listeria monocytogenes (Lm)-based immunotherapy designed to generate immune responses against mutation-derived tumor-specific neoantigens. Advaxis' Lm-based immunotherapies consist of live highly-attenuated bacterial vectors that are bioengineered to secrete a fusion protein consisting of a truncated non-hemolytic fragment of listeriolysin O, which has adjuvant properties, and tumor-specific neoantigens that harbor nonsynonymous point mutations (NSMs). The objective of this study is to demonstrate the feasibility of using the ADXS-NEO platform to target tumor-specific point mutations to generate neoantigen-specific T cells and control tumor growth. Results: Whole-exome sequencing of the MC38 mouse tumor cell line identified 2870 unique NSMs. Among these, the IC50 of 138 NSMs were predicted to be less than 500 nM by the netMHCcons algorithm. We evaluated the immunogenicity of 37 NSMs, and found that 12 immunogenic NSMs elicited a CD8+ T cell response following peptide immunization. Moreover, we identified 10 additional immunogenic NSMs in MC38-bearing mice treated with a check point inhibitor. Altogether, we identified 22 immunogenic and 23 non-immunogenic NSMs. Two ADXS-NEO vectors were constructed, Lm-19 & Lm-20, targeting 19 non-immunogenic and 20 immunogenic NSMs respectively. The ability of Lm-19 and Lm-20 to control MC38 tumor growth was evaluated in C57BL/6J mice. We found that both Lm-19 & Lm-20 led to an accumulation of neoantigen-specific CD8+ TILs and significantly slowed tumor growth. Moreover, both Lm-19 and Lm-20 decreased the frequency and absolute number of intratumoral Tregs, TAMs, and MDSCs and increased the frequency and absolute number of effector CD8+ T cells. Interestingly, expression of PD-L1 was decreased in TAMs and MDSCs and the frequency and total number of granzyme A+ CD8+ effector T cells was increased. Furthermore, the proportion of phenotypically exhausted PD-1hiLAG3+ TILs was decreased. Together, these data suggest the tumor microenvironment in mice receiving Lm-19 and Lm-20 becomes more cytotoxic and less suppressive. Conclusion: ADXS-NEO is a potent immunotherapy capable of driving immune responses against tumor-specific mutations and leading to tumor control. The effectiveness of the Lm platform is demonstrated by the generation of neoantigen-specific T cells to peptide sequences that were identified as “non-immunogenic” using a conventional peptide-adjuvant immunization. This study is a clear demonstration that T cell mediated anti-tumor responses can be generated by targeting tumor-derived NSMs with the ADXS-NEO Listeria monocytogenes vector. Citation Format: Brandon Coder, Hyewon Phee, Cristina Mottershead, Dipti Kelkar, Elena Filippova, Xiaoming Ju, Bryan Vander Lugt, Olga Pryshchep, Justin Lesch, Xian Liu, Jason DeVoss, Keegan Cooke, Claret Liu, Jinghui Zhan, Petia Mitchell, Kim Ramos, Daniel O. Villarreal, Jim Johnston, Robert Petit, Michael Princiotta. Neoantigens that fail to elicit measurable T cell responses following peptide immunization can control tumor growth when delivered using a Listeria-based immunotherapy platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-150.

Sjögren’s Syndrome (SS) is a human autoimmune disease characterized by immune-mediated destruction of the lacrimal and salivary glands. In this study, we show that the Aire-deficient mouse represents a new tool to investigate autoimmune dacryoadenitis and keratoconjunctivitis sicca, features of SS. Previous work in the Aire-deficient mouse suggested a role for α-fodrin, a ubiquitous Ag, in the disease process. Using an unbiased biochemical approach, however, we have identified a novel lacrimal gland autoantigen, odorant binding protein 1a, targeted by the autoimmune response. This novel autoantigen is expressed in the thymus in an Aire-dependent manner. The results from our study suggest that defects in central tolerance may contribute to SS and provide a new and clinically relevant model to investigate the pathogenic mechanisms in lacrimal gland autoimmunity and associated ocular surface sequelae.

Summary Inflammatory responses mediated by NOD2 rely on RIP2 kinase and ubiquitin ligase XIAP for the activation of nuclear factor κB (NF-κB), mitogen-activated protein kinases (MAPKs), and cytokine production. Herein, we demonstrate that selective XIAP antagonism blocks NOD2-mediated inflammatory signaling and cytokine production by interfering with XIAP-RIP2 binding, which removes XIAP from its ubiquitination substrate RIP2. We also establish that the kinase activity of RIP2 is dispensable for NOD2 signaling. Rather, the conformation of the RIP2 kinase domain functions to regulate binding to the XIAP-BIR2 domain. Effective RIP2 kinase inhibitors block NOD2 signaling by disrupting RIP2-XIAP interaction. Finally, we identify NOD2 signaling and XIAP-dependent ubiquitination sites on RIP2 and show that mutating these lysine residues adversely affects NOD2 pathway signaling. Overall, these results reveal a critical role for the XIAP-RIP2 interaction in NOD2 inflammatory signaling and provide a molecular basis for the design of innovative therapeutic strategies based on XIAP antagonists and RIP2 kinase inhibitors.

Mutations in the Aire gene result in a clinical phenomenon known as Autoimmune Polyglandular Syndrome (APS) Type I, which classically manifests as a triad of adrenal insufficiency, hypoparathyroidism, and chronic mucocutaneous infections. In addition to this triad, a number of other autoimmune diseases have been observed in APS1 patients including Sjögren’s syndrome, vitiligo, alopecia, uveitis, and others. Aire-deficient mice, the animal model for APS1, have highlighted the role of the thymus in the disease process and demonstrated a failure in central tolerance in aire-deficient mice. However, autoantibodies have been observed against multiple organs in both mice and humans, making it unclear what the specific role of B and T cells are in the pathogenesis of disease. Using the aire-deficient mouse as a preclinical model for APS1, we have investigated the relative contribution of specific lymphocyte populations, with the goal of identifying the cell populations which may be targeted for rational therapeutic design. In this study, we show that T cells are indispensable to the breakdown of self-tolerance, in contrast to B cells which play a more limited role in autoimmunity. Th1 polarized CD4+ T cells, in particular, are major contributors to the autoimmune response. With this knowledge, we go on to use therapies targeted at T cells to investigate their ability to modulate disease in vivo. Depletion of CD4+ T cells using a neutralizing Ab ameliorated the disease process. Thus, therapies targeted specifically at the CD4+ T cell subset may help control autoimmune disease in patients with APS1.

Homozygous loss-of-function mutations in AIRE cause autoimmune polyglandular syndrome type 1 (APS 1), which manifests in a classic triad of hypoparathyroidism, adrenal insufficiency, and candidiasis. Interestingly, a kindred with a specific G228W AIRE variant presented with an autosomal dominant autoimmune phenotype distinct from APS 1. We utilized a novel G228W-knockin mouse model to show that this variant acted in a dominant-negative manner to cause a unique autoimmunity syndrome. In addition, the expression of a large number of Aire-regulated thymic antigens was partially inhibited in these animals, demonstrating the importance of quantitative changes in thymic antigen expression in determining organ-specific autoimmunity. Furthermore, the dominant-negative effect of the G228W variant was exerted through recruitment of WT Aire away from active sites of transcription in the nucleus of medullary thymic epithelial cells in vivo. Together, these results may demonstrate a mechanism by which autoimmune predisposition to phenotypes distinct from APS 1 can be mediated in a dominant-negative fashion by Aire.

SummaryThe blood-brain barrier (BBB) limits brain uptake of therapeutic antibodies. It is believed that the BBB is disrupted in Alzheimer’s disease (AD), potentially increasing drug permeability de facto. Here we compared active versus passive brain uptake of systemically dosed antibodies (anti-transferrin receptor [TfR] bispecific versus control antibody) in mouse models of AD. We first confirmed BBB disruption in a mouse model of multiple sclerosis as a positive control. Importantly, we found that BBB permeability was vastly spared in mouse models of AD, including PS2-APP, Tau transgenics, and APOE4 knockin mice. Brain levels of TfR in mouse models or in human cases of AD resembled controls, suggesting target engagement of TfR bispecific is not limited. Furthermore, infarcts from human AD brain showed similar occurrences compared to age-matched controls. These results question the widely held view that the BBB is largely disrupted in AD, raising concern about assumptions of drug permeability in disease.

Background Idiopathic pulmonary fibrosis (IPF) is associated with aberrant expression of developmental pathways, including Hedgehog (Hh). As Hh signalling contributes to multiple pro-fibrotic processes, Hh inhibition may represent a therapeutic option for IPF. However, no non-invasive biomarkers are available to monitor lung Hh activity. Methods We assessed gene and protein expression in IPF and control lung biopsies, mouse lung, fibroblasts stimulated in vitro with sonic hedgehog (SHh), and plasma in IPF patients versus controls, and cancer patients before and after treatment with vismodegib, a Hh inhibitor. Results Lung tissue from IPF patients exhibited significantly greater expression of Hh-related genes versus controls. The gene most significantly upregulated in both IPF lung biopsies and fibroblasts stimulated in vitro with SHh was CXCL14 , which encodes a soluble secreted chemokine whose expression is inhibited in vitro by the addition of vismodegib. CXCL14 expression was induced by SHh overexpression in mouse lung. Circulating CXCL14 protein levels were significantly higher in plasma from IPF patients than controls. In cancer patients, circulating CXCL14 levels were significantly reduced upon vismodegib treatment. Conclusions CXCL14 is a systemic biomarker that could be used to identify IPF patients with increased Hh pathway activity and monitor the pharmacodynamic effects of Hh antagonist therapy in IPF. Trial registration number Post-results, NCT00968981.

Rheumatoid arthritis (RA) is a chronic debilitating autoimmune disorder characterized by synovitis that leads to cartilage and bone erosion by invading fibrovascular tissue. Mouse models of RA recapitulate many features of the human disease. Despite the availability of medicines that are highly effective in many patient populations, autoimmune diseases (including RA) remain an area of active biomedical research, and consequently mouse models of RA are still extensively used for mechanistic studies and validation of therapeutic targets. This review aims to integrate morphologic features with model biology and cover the key characteristics of the most commonly used induced and spontaneous mouse models of RA. Induced models emphasized in this review include collagen-induced arthritis and antibody-induced arthritis. Collagen-induced arthritis is an example of an active immunization strategy, whereas antibody- induced arthritis models, such as collagen antibody–induced arthritis and K/BxN antibody transfer arthritis, represent examples of passive immunization strategies. The coverage of spontaneous models in this review is focused on the TNFΔ ARE mouse, in which arthritis results from overexpression of TNF-α, a master proinflammatory cytokine that drives disease in many patients.