Purpose: Recent clinical trials and animal models demonstrated that immune checkpoint blockade enhanced effector cell responses and tumor rejection; however, further development and improvement of cancer immunotherapy is necessary for more favorable objective responses. In this study, we examined the effect of IL18 on the antitumor effect of immune checkpoint inhibitors. Experimental Design: We examined the effect of IL18 on the peritoneal dissemination of CT-26 cells or tail vein injection metastasis of B16/F10 cells using antiprogrammed death-1 ligand-1 (αPD-L1) and/or anti-CTL–associated antigen-4 (αCTLA-4) mAbs. Result: Massive ascites developed after intraperitoneal inoculation of CT-26, resulting in animal death within 30 days. Treatment of mice with αPD-L1 and/or αCTLA-4 significantly prolonged their survival, and a combination of the antibodies and IL18 provided a much greater therapeutic benefit. The combination modality led to the accumulation of precursor of mature natural killer (pre-mNK) cells in the peritoneal cavity together with increased CD8+ T and decreased CD4+CD25+Foxp3+ T cells. Depletion of the pre-mNK cells abrogated the therapeutic effects and increased the number of CD4+CD25+Foxp3+ T cells. The combination treatment also suppressed tail vein injection metastasis of B16/F10 cells. Conclusions: The results demonstrated that IL18 enhanced therapeutic effects of immune checkpoint blockade against peritoneal dissemination of carcinoma or tail vein injection metastasis of melanoma through accumulation of pre-mNK cells, memory-type CD8+ T cells, and suppression of CD4+CD25+Foxp3+ T cells. A combination of immune checkpoint inhibitors with IL18 may give a suggestion to the development of next-generation cancer immunotherapy. Clin Cancer Res; 22(12); 2969–80. ©2016 AACR.

Spontaneously hypertensive rats (SHR) and stroke-prone SHR (SHRSP) are frequently used as model rats not only in studies of essential hypertension and stroke, but also in studies of attention deficit hyperactivity disorder (ADHD). Normotensive Wistar-Kyoto rats (WKY) are normally used as controls in these studies. In this study, using these rats, we aimed to identify the genes causing hypertension and stroke, as well as the genes involved in ADHD. Since adrenal gland products can directly influence cardiovascular, endocrine and sympathetic nervous system functions, gene expression profiles in the adrenal glands of the 3 rat strains were examined using genome-wide microarray technology when the rats were 3 and 6 weeks of age, a period in which the rats are considered to be in a pre-hypertensive state. Gene expression profiles were compared between SHR and WKY and between SHRSP and SHR. A total of 353 genes showing more than a 4-fold increase or less than a 4-fold decrease in expression were isolated and candidate genes were selected as significantly enriched genes. SHR-specific genes isolated when the rats were 3 weeks of age contained 12 enriched genes related to transcriptional regulatory activity and those isolated when the rats were 6 weeks of age contained 6 enriched genes related to the regulation of blood pressure. SHRSP-specific genes isolated when the rats were 3 weeks of age contained 4 enriched genes related to the regulation of blood pressure and those isolated when the rats were 6 weeks of age contained 4 enriched genes related to the response to steroid hormone stimulus. Ingenuity pathway analysis of enriched SHR-specific genes revealed that 2 transcriptional regulators, cAMP responsive element modulator (Crem) and Fos-like antigen 1 (Fosl1), interact with blood pressure-regulating genes, such as neurotensin (Nts), apelin (Apln) and epoxide hydrolase 2, cytoplasmic (Ephx2). Similar analyses of SHRSP-specific genes revealed that angiotensinogen (Agt), one of the blood pressure-regulating genes, plays pivotal roles among SHRSP-specific genes. Moreover, genes associated with ADHD, such as low density lipoprotein receptor (Ldlr) and Crem, are discussed.

Increased levels of lactate, an end-product of glycolysis, have been proposed as a potential surrogate marker for metabolic changes during neuronal excitation. These changes in lactate levels can result in decreased brain pH, which has been implicated in patients with various neuropsychiatric disorders. We previously demonstrated that such alterations are commonly observed in five mouse models of schizophrenia, bipolar disorder, and autism, suggesting a shared endophenotype among these disorders rather than mere artifacts due to medications or agonal state. However, there is still limited research on this phenomenon in animal models, leaving its generality across other disease animal models uncertain. Moreover, the association between changes in brain lactate levels and specific behavioral abnormalities remains unclear. To address these gaps, the International Brain pH Project Consortium investigated brain pH and lactate levels in 109 strains/conditions of 2294 animals with genetic and other experimental manipulations relevant to neuropsychiatric disorders. Systematic analysis revealed that decreased brain pH and increased lactate levels were common features observed in multiple models of depression, epilepsy, Alzheimer’s disease, and some additional schizophrenia models. While certain autism models also exhibited decreased pH and increased lactate levels, others showed the opposite pattern, potentially reflecting subpopulations within the autism spectrum. Furthermore, utilizing large-scale behavioral test battery, a multivariate cross-validated prediction analysis demonstrated that poor working memory performance was predominantly associated with increased brain lactate levels. Importantly, this association was confirmed in an independent cohort of animal models. Collectively, these findings suggest that altered brain pH and lactate levels, which could be attributed to dysregulated excitation/inhibition balance, may serve as transdiagnostic endophenotypes of debilitating neuropsychiatric disorders characterized by cognitive impairment, irrespective of their beneficial or detrimental nature.

Major depressive disorder (MDD) is a common psychiatric disorder that involves marked disabilities in global functioning, anorexia, and severe medical comorbidities. MDD is associated with not only psychological and sociocultural problems, but also pervasive physical dysfunctions such as metabolic, neurobiological and immunological abnormalities. Nevertheless, the mechanisms underlying the interactions between these factors have yet to be determined in detail. The aim of the present study was to identify the molecular mechanisms responsible for the interactions between MDD and dysregulation of physiological homeostasis, including immunological function as well as lipid metabolism, coagulation, and hormonal activity in the brain. We generated depression-like behavior in mice using chronic mild stress (CMS) as a model of depression. We compared the gene expression profiles in the prefrontal cortex (PFC) of CMS and control mice using microarrays. We subsequently categorized genes using two web-based bioinformatics applications: Ingenuity Pathway Analysis and The Database for Annotation, Visualization, and Integrated Discovery. We then confirmed significant group-differences by analyzing mRNA and protein expression levels not only in the PFC, but also in the thalamus and hippocampus. These web tools revealed that hepatocyte nuclear factor 4 alpha (Hnf4a) may exert direct effects on various genes specifically associated with amine synthesis, such as genes involved in serotonin metabolism and related immunological functions. Moreover, these genes may influence lipid metabolism, coagulation, and hormonal activity. We also confirmed the significant effects of Hnf4a on both mRNA and protein expression levels in the brain. These results suggest that Hnf4a may have a critical influence on physiological homeostasis under depressive states, and may be associated with the mechanisms responsible for the interactions between MDD and the dysregulation of physiological homeostasis in humans.

Interleukin 18 (IL18) was originally identified as an inflammation-induced cytokine that is secreted by immune cells. An increasing number of studies have focused on its non-immunological functions, with demonstrated functions for IL18 in energy homeostasis and neural stability. IL18 is reportedly required for lipid metabolism in the liver and brown adipose tissue. Furthermore, IL18 (Il18) deficiency in mice leads to mitochondrial dysfunction in hippocampal cells, resulting in depressive-like symptoms and cognitive impairment. Microarray analyses of Il18^−/− mice have revealed a set of genes with differential expression in liver, brown adipose tissue, and brain; however, the impact of IL18 deficiency in these tissues remains uncertain. In this review article, we discuss these genes, with a focus on their relationships with the phenotypic disease traits of Il18^−/− mice.