Modeling psychiatric disorders: from genomic findings to cellular phenotypes

Major programs in psychiatric genetics have identified 4150 risk loci for psychiatric disorders. These loci converge on a small number of functional pathways, which span conventional diagnostic criteria, suggesting a partly common biology underlying schizophrenia, autism and other psychiatric disorders. Nevertheless, the cellular phenotypes that capture the fundamental features of psychiatric disorders have not yet been determined. Recent advances in genetics and stem cell biology offer new prospects for cell-based modeling of psychiatric disorders. The advent of cell reprogramming and induced pluripotent stem cells (iPSC) provides an opportunity to translate genetic findings into patient-specific in vitro models. iPSC technology is less than a decade old but holds great promise for bridging the gaps between patients, genetics and biology. Despite many obvious advantages, iPSC studies still present multiple challenges. In this expert review, we critically review the challenges for modeling of psychiatric disorders, potential solutions and how iPSC technology can be used to develop an analytical framework for the evaluation and therapeutic manipulation of fundamental disease processes

The Relation of P300 Latency to Reaction Time as Function of Expectancy

This chapter discusses the relation of P300 latency to reaction time as a function of expectancy. The amplitude of the P300 component of the event-related potential (ERP) is inversely related to the subjective probability, or “expectancy,” for a task-relevant event. The assertion that P300 reflects the timing of stimulus evaluation has sometimes been interpreted as implying that P300 latency is positively correlated with reaction time (RT). The finding that, under certain conditions, P300 and RT is dissociated need not, however, cast doubt on the validity of P300 latency as a measure of processing time. Data showing dissociation may be reconciled by noting that the subject\u27s response is only one of many possible consequences of stimulus presentation, rather than the end point of information processing activities invoked by a stimulus. It is thus plausible to expect P300 latency to be determined by one subset of the processes invoked by a stimulus and RT to be determined by another. Since stimuli may initiate multiple, parallel processes, the relative timing of P300 and RT would then depend on the degree of overlap between the processes of stimulus evaluation and response selection

A Preclinical Model of Malignant Peripheral Nerve Sheath Tumor-like Melanoma Is Characterized by Infiltrating Mast Cells

Human melanomas exhibit considerable genetic, pathologic, and microenvironmental heterogeneity. Genetically engineered mice have successfully been used to model the genomic aberrations contributing to melanoma pathogenesis, but their ability to recapitulate the phenotypic variability of human disease and the complex interactions with the immune system have not been addressed. Here, we report the unexpected finding that immune cell-poor pigmented and immune cell-rich amelanotic melanomas developed simultaneously in Cdk4R24C-mutant mice upon melanocyte-specific conditional activation of oncogenic BrafV600E and a single application of the carcinogen 7,12-dimethylbenz(a) anthracene. Interestingly, amelanotic melanomas showed morphologic and molecular features of malignant peripheral nerve sheath tumors (MPNST). A bioinformatic cross-species comparison using a gene expression signature of MPNST-like mouse melanomas identified a subset of human melanomas with a similar histomorphology. Furthermore, this subset of human melanomas was found to be highly associated with a mast cell gene signature, and accordingly, mouse MPNST-like melanomas were also extensively infiltrated by mast cells and expressed mast cell chemoattractants similar to human counterparts. A transplantable mouse MPNST-like melanoma cell line recapitulated mast cell recruitment in syngeneic mice, demonstrating that this cell state can directly reconstitute the histomorphologic and microenvironmental features of primary MPNST-like melanomas. Our study emphasizes the importance of reciprocal, phenotype-dependent melanoma-immune cell interactions and highlights a critical role for mast cells in a subset of melanomas. Moreover, our BrafV600E-Cdk4R24C model represents an attractive system for the development of therapeutic approaches that can target the heterogeneous tumor microenvironment characteristic of human melanomas. (C) 2015 AACR

Combined immunotherapy with nivolumab and ipilimumab with and without local therapy in patients with melanoma brain metastasis: a DeCOG* study in 380 patients

BackgroundNivolumab combined with ipilimumab have shown activity in melanoma brain metastasis (MBM). However, in most of the clinical trials investigating immunotherapy in this subgroup, patients with symptomatic MBM and/or prior local brain radiotherapy were excluded. We studied the efficacy of nivolumab plus ipilimumab alone or in combination with local therapies regardless of treatment line in patients with asymptomatic and symptomatic MBM.MethodsPatients with MBM treated with nivolumab plus ipilimumab in 23 German Skin Cancer Centers between April 2015 and October 2018 were investigated. Overall survival (OS) was evaluated by Kaplan-Meier estimator and univariate and multivariate Cox proportional hazard analyses were performed to determine prognostic factors associated with OS.ResultsThree hundred and eighty patients were included in this study and 31% had symptomatic MBM (60/193 with data available) at the time of start nivolumab plus ipilimumab. The median follow-up was 18 months and the 2 years and 3 years OS rates were 41% and 30%, respectively. We identified the following independently significant prognostic factors for OS: elevated serum lactate dehydrogenase and protein S100B levels, number of MBM and Eastern Cooperative Oncology Group performance status. In these patients treated with checkpoint inhibition first-line or later, in the subgroup of patients with BRAFV600-mutated melanoma we found no differences in terms of OS when receiving first-line either BRAF and MEK inhibitors or nivolumab plus ipilimumab (p=0.085). In BRAF wild-type patients treated with nivolumab plus ipilimumab in first-line or later there was also no difference in OS (p=0.996). Local therapy with stereotactic radiosurgery or surgery led to an improvement in OS compared with not receiving local therapy (p=0.009), regardless of the timepoint of the local therapy. Receiving combined immunotherapy for MBM in first-line or at a later time point made no difference in terms of OS in this study population (p=0.119).ConclusionImmunotherapy with nivolumab plus ipilimumab, particularly in combination with stereotactic radiosurgery or surgery improves OS in asymptomatic and symptomatic MBM

Amplification of N-Myc is associated with a T-cell-poor microenvironment in metastatic neuroblastoma restraining interferon pathway activity and chemokine expression

Immune checkpoint inhibitors have significantly improved the treatment of several cancers. T-cell infiltration and the number of neoantigens caused by tumor-specific mutations are correlated to favorable responses in cancers with a high mutation load. Accordingly, checkpoint immunotherapy is thought to be less effective in tumors with low mutation frequencies such as neuroblastoma, a neuroendocrine tumor of early childhood with poor outcome of the high-risk disease group. However, spontaneous regressions and paraneoplastic syndromes seen in neuroblastoma patients suggest substantial immunogenicity. Using an integrative transcriptomic approach, we investigated the molecular characteristics of T-cell infiltration in primary neuroblastomas as an indicator of pre-existing immune responses and potential responsiveness to checkpoint inhibition. Here, we report that a T-cell-poor microenvironment in primary metastatic neuroblastomas is associated with genomic amplification of the MYCN (N-Myc) proto-oncogene. These tumors exhibited lower interferon pathway activity and chemokine expression in line with reduced immune cell infiltration. Importantly, we identified a global role for N-Myc in the suppression of interferon and pro-inflammatory pathways in human and murine neuroblastoma cell lines. N-Myc depletion potently enhanced targeted interferon pathway activation by a small molecule agonist of the cGAS-STING innate immune pathway. This promoted chemokine expression including Cxcl10 and T-cell recruitment in microfluidics migration assays. Hence, our data suggest N-Myc inhibition plus targeted IFN activation as adjuvant strategy to enforce cytotoxic T-cell recruitment in MYCN-amplified neuroblastomas

A key role of GARP in the immune suppressive tumor microenvironment

In melanoma patients, one of the main reasons for tumor immune escape and therapy failure is the immunosuppressive tumor microenvironment. Herein, suppressive immune cells and inhibitory factors secreted by the tumor itself play a central role. In the present study we show that the Treg activation marker GARP (glycoprotein A repetitions predominant), known to induce peripheral tolerance in a TGF-β dependent way, is also expressed on human primary melanoma. Interestingly, membrane bound GARP is shed from the surface of both, activated Treg and melanoma cells, and, in its soluble form (sGARP), not only induces peripheral Treg but also a tumor associated (M2) macrophage phenotype. Notably, proliferation of cytotoxic T cells and their effector function is inhibited in the presence of sGARP. GARP expression on Treg and melanoma cells is significantly decreased in the presence of agents such as IFN-α, thus explaining at least in part a novel mechanism of action of this adjuvant therapy. In conclusion, GARP in its soluble and membrane bound form contributes to peripheral tolerance in a multipronged way, potentiates the immunosuppressive tumor microenvironment and thus acts as a negative regulator in melanoma patients. Therefore, it may qualify as a promising target and a new checkpoint for cancer immunotherapy

Loss-of-function mutations in the filaggrin gene and alopecia areata: Strong risk factor for a severe course of disease in patients comorbid for atopic disease

Alopecia areata (AA) is a common dermatological disease, which affects nearly 2% of the general population. Association of AA with atopic disease has been repeatedly reported. Loss-of-function mutations in the filaggrin gene (FLG) may be considered as promising candidates in AA, as they have been observed to be a strong risk factor in atopic dermatitis. The FLG mutations R501X and 2282del4 were genotyped in a large sample of AA patients (n=449) and controls (n=473). Although no significant association was observed in the patient sample overall, FLG mutations were significantly associated with the presence of atopic dermatitis among AA patients. Furthermore, the presence of FLG mutations had a strong impact on the clinical course of AA in comorbid patients. For example, 19 of the 22 mutation carriers among AA patients with atopic dermatitis showed a severe form of the disease ( P 0.003; odds ratio ( OR) 5.47 ( 95% confidence interval (CI): 1.59-18.76)). In conclusion, our data suggest that when AA occurs in conjunction with FLG-associated atopic disorder, the clinical presentation of AA may be more severe

Adoptive T Cell Therapy Targeting Different Gene Products Reveals Diverse and Context-Dependent Immune Evasion in Melanoma

Tumor immune escape limits durable responses to T cell therapy. Here, we examined how regulation and function of gene products that provide the target epitopes for CD8(+) T cell anti-tumor immunity influence therapeutic efficacy and resistance. We used a CRISPR-Cas9-based method (CRISPitope) in syngeneic melanoma models to fuse the same model CD8(+) T cell epitope to the C-termini of different endogenous gene products. Targeting melanosomal proteins or oncogenic CDK4(R24C )(Cyclin-dependent kinase 4) by adoptive cell transfer (ACT) of the same epitope-specific CD8(+) T cells revealed diverse genetic and non-genetic immune escape mechanisms. ACT directed against melanosomal proteins, but not CDK4(R24C), promoted melanoma dedifferentiation, and increased myeloid cell infiltration. CDK4(R24C) antigen persistence was associated with an interferon-high and T-cell-rich tumor microenvironment, allowing for immune checkpoint inhibition as salvage therapy. Thus, the choice of target antigen determines the phenotype and immune contexture of recurrent melanomas, with implications to the design of cancer immunotherapies

RIG-I activation induces the release of extracellular vesicles with antitumor activity

Activation of the innate immune receptor retinoic acid-inducible gene I (RIG-I) by its specific ligand 5-triphosphate-RNA (3pRNA) triggers antitumor immunity predominantly via NK cell activation and direct apoptosis induction in tumor cells. However, how NK cells are mobilized to attack the tumor cells remains elusive. Here, we show that RIG-I activation induced the secretion of extracellular vesicles (EVs) from melanoma cells, which by themselves revealed antitumor activity in vitro and in vivo. RIG-I-induced EVs from melanoma cells exhibited an increased expression of the NKp30-ligand (BAG6, BAT3) on their surface triggering NK cell-mediated lysis of melanoma cells via activation of the cytotoxicity NK cell-receptor NKp30. Moreover, systemic administration of RIG-I-induced melanoma-EVs showed a potent antitumor activity in a melanoma mouse model in vivo. In conclusion, our data establish a new RIG-I-dependent pathway leading to NK cell-mediated tumor cell killing

MAPK signaling and inflammation link melanoma phenotype switching to induction of CD73 during immunotherapy

Evolution of tumor cell phenotypes promotes heterogeneity and therapy resistance. Here we found that induction of CD73, the enzyme that generates immunosuppressive adenosine, is linked to melanoma phenotype switching. Activating MAPK mutations and growth factors drove CD73 expression, which marked both nascent and full activation of a mesenchymal-like melanoma cell state program. Proinflammatory cytokines like TNF alpha cooperated with MAPK signaling through the c-Jun/AP-1 transcription factor complex to activate CD73 transcription by binding to an intronic enhancer. In a mouse model of T-cell immunotherapy, CD73 was induced in relapse melanomas, which acquired a mesenchymal-like phenotype. We also detected CD73 upregulation in melanoma patients progressing under adoptive T-cell transfer or immune checkpoint blockade, arguing for an adaptive resistance mechanism. Our work substantiates CD73 as a target to combine with current immunotherapies, but its dynamic regulation suggests limited value of CD73 pretreatment expression as a biomarker to stratify melanoma patients. (C) 2017 AACR