Investigating 7,8-Dihydroxyflavone to combat maternal immune activation effects on offspring gene expression and behaviour.

Infection during pregnancy is a substantial risk factor for the unborn child to develop autism or schizophrenia later in life, and is thought to be driven by maternal immune activation (MIA). MIA can be modelled by exposing pregnant mice to Polyinosinic: polycytidylic acid (Poly-I:C), a viral mimetic that induces an immune response and recapitulates in the offspring many neurochemical features of ASD and schizophrenia, including altered BDNF-TrkB signalling and disruptions to excitatory/inhibitory balance. Therefore, we hypothesised that a BDNF mimetic, 7,8-Dihydroxyflavone (7,8-DHF), administered prophylactically to the dam may prevent the neurobehavioural sequelae of disruptions induced by MIA. Dams were treated with 7,8-DHF in the drinking water (0.08 mg/ML) from gestational day (GD) 9-20 and were exposed to Poly-I:C at GD17 (20 mg/kg, i.p.). Foetal brains were collected 6 h post Poly-I:C exposure for RT-qPCR analysis of BDNF, cytokine, GABAergic and glutamatergic gene targets. A second adult cohort were tested in a battery of behavioural tests relevant to schizophrenia and the prefrontal cortex and ventral hippocampus dissected for RT-qPCR analysis. Foetal brains exposed to Poly-I:C showed increased IL-6, but reduced expression of Ntrk2 and multiple GABAergic and glutamatergic markers. Anxiety-like behaviour was observed in adult offspring prenatally exposed to poly-I:C, which was accompanied by altered expression of Gria2 in the prefrontal cortex and Gria4 in the ventral hippocampus. While 7-8 DHF normalised the expression of some glutamatergic (Grm5) and GABAergic (Gabra1) genes in Poly-I:C exposed offspring, it also led to substantial alterations in offspring not exposed to Poly-I:C. Furthermore, mice exposed to 7,8-DHF prenatally showed increased pre-pulse inhibition and reduced working memory in adulthood. These data advance understanding of how 7,8-DHF and MIA prenatal exposure impacts genes critical to excitatory/inhibitory pathways and related behaviour.

The impact of maternal immune activation on GABAergic interneuron development: A systematic review of rodent studies and their translational implications.

Mothers exposed to infections during pregnancy disproportionally birth children who develop autism and schizophrenia, disorders associated with altered GABAergic function. The maternal immune activation (MIA) model recapitulates this risk factor, with many studies also reporting disruptions to GABAergic interneuron expression, protein, cellular density and function. However, it is unclear if there are species, sex, age, region, or GABAergic subtype specific vulnerabilities to MIA. Furthermore, to fully comprehend the impact of MIA on the GABAergic system a synthesised account of molecular, cellular, electrophysiological and behavioural findings was required. To this end we conducted a systematic review of GABAergic interneuron changes in the MIA model, focusing on the prefrontal cortex and hippocampus. We reviewed 102 articles that revealed robust changes in a number of GABAergic markers that present as gestationally-specific, region-specific and sometimes sex-specific. Disruptions to GABAergic markers coincided with distinct behavioural phenotypes, including memory, sensorimotor gating, anxiety, and sociability. Findings suggest the MIA model is a valid tool for testing novel therapeutics designed to recover GABAergic function and associated behaviour.

Maternal selenium dietary supplementation alters sociability and reinforcement learning deficits induced by in utero exposure to maternal immune activation in mice.

Maternal immune activation (MIA) during pregnancy increases the risk for the unborn foetus to develop neurodevelopmental conditions such as autism spectrum disorder and schizophrenia later in life. MIA mouse models recapitulate behavioural and biological phenotypes relevant to both conditions, and are valuable models to test novel treatment approaches. Selenium (Se) has potent anti-inflammatory properties suggesting it may be an effective prophylactic treatment against MIA. The aim of this study was to determine if Se supplementation during pregnancy can prevent adverse effects of MIA on offspring brain and behaviour in a mouse model. Selenium was administered via drinking water (1.5 ppm) to pregnant dams from gestational day (GD) 9 to birth, and MIA was induced at GD17 using polyinosinic:polycytidylic acid (poly-I:C, 20 mg/kg via intraperitoneal injection). Foetal placenta and brain cytokine levels were assessed using a Luminex assay and brain elemental nutrients assessed using inductively coupled plasma- mass spectrometry. Adult offspring were behaviourally assessed using a reinforcement learning paradigm, the three-chamber sociability test and the open field test. MIA elevated placental IL-1ß and IL-17, and Se supplementation successfully prevented this elevation. MIA caused an increase in foetal brain calcium, which was prevented by Se supplement. MIA caused in offspring a female-specific reduction in sociability, which was recovered by Se, and a male-specific reduction in social memory, which was not recovered by Se. Exposure to poly-I:C or selenium, but not both, reduced performance in the reinforcement learning task. Computational modelling indicated that this was predominantly due to increased exploratory behaviour, rather than reduced rate of learning the location of the food reward. This study demonstrates that while Se may be beneficial in ameliorating sociability deficits caused by MIA, it may have negative effects in other behavioural domains. Caution in the use of Se supplementation during pregnancy is therefore warranted.

TrkB agonist 7,8-dihydroxyflavone reverses an induced prepulse inhibition deficit selectively in maternal immune activation offspring: implications for schizophrenia.

Reduced brain-derived neurotrophic factor (BDNF) signalling has been implicated in schizophrenia endophenotypes, including deficits in prepulse inhibition (PPI). Maternal immune activation (MIA) is a widely used neurodevelopmental animal model for schizophrenia but it is unclear if BDNF and its receptor, tropomyosin receptor kinase B (TrkB), are involved in PPI regulation in this model. Pregnant Long Evans rats were treated with the viral mimetic, polyinosinic-polycytidylic acid (poly I:C; 4 mg/kg i.v.), and nine male offspring from these dams were compared in adulthood to 11 male Long Evans controls. Offspring underwent PPI testing following injection with the TrkB agonist, 7,8-dihydroxyflavone (7,8-DHF) (10 mg/kg i.p.), with or without the dopamine receptor agonist, apomorphine (APO; 1 mg/kg s.c.), or the dopamine releasing drug, methamphetamine (METH; 2 mg/kg s.c.). Acute administration of APO and METH caused the expected significant reduction of PPI. Acute administration of 7,8-DHF did not alter PPI on its own; however, it significantly reversed the effect of APO on PPI in poly I:C rats, but not in controls. A similar trend was observed in combination with METH. Western blot analysis of frontal cortex revealed significantly increased levels of BDNF protein, but not TrkB or phosphorylated TrkB/TrkB levels, in poly I:C rats. These findings suggest that, selectively in MIA offspring, 7,8-DHF has the ability to reverse PPI deficits caused by dopaminergic stimulation. This effect could be associated with increased BDNF expression in the frontal cortex. These data suggest that targeting BDNF signalling may have therapeutic potential for the treatment of certain symptoms of schizophrenia.

Maternal immune activation targeted to a window of parvalbumin interneuron development improves spatial working memory: Implications for autism.

Maternal immune activation (MIA) increases risk for neuropsychiatric disorders such as autism spectrum disorder (ASD) in offspring later in life through unknown causal mechanisms. Growing evidence implicates parvalbumin-containing GABAergic interneurons as a key target in rodent MIA models. We targeted a specific neurodevelopmental window of parvalbumin interneurons in a mouse MIA model to examine effects on spatial working memory, a key domain in ASD that can manifest as either impairments or improvements both clinically and in animal models. Pregnant dams received three consecutive intraperitoneal injections of Polyinosinic:polycytidylic acid (poly(I:C), 5 mg/kg) at gestational days 13, 14 and 15. Spatial working memory was assessed in young adult offspring using touchscreen operant chambers and the Trial-Unique Non-matching to Location (TUNL) task. Anxiety, novelty seeking and short-term memory were assessed using Elevated Plus Maze (EPM) and Y-maze novelty preference tasks. Fluorescent immunohistochemistry was used to assess hippocampal parvalbumin cell density, intensity and co-expression with perineuronal nets. qPCR was used to assess the expression of putatively implicated gene pathways. MIA targeting a window of parvalbumin interneuron development increased spatial working memory performance on the TUNL touchscreen task which was not influenced by anxiety or novelty seeking behaviour. The model reduced fetal mRNA levels of Gad1 and adult hippocampal mRNA levels of Pvalb and the distribution of low intensity parvalbumin interneurons was altered. We speculate a specific timing window for parvalbumin interneuron development underpins the apparently paradoxical improved spatial working memory phenotype found both across several rodent models of autism and clinically in ASD.

Pan-Cancer Landscape Analysis Reveals Recurrent KMT2A-MAML2 Gene Fusion in Aggressive Histologic Subtypes of Thymoma.

PURPOSE: Thymomas are epithelial neoplasms that represent the most common thymic tumors in adults. These tumors have been shown to harbor a relatively low mutational burden. As a result, there is a lack of genetic alterations that may be used prognostically or targeted therapeutically for this disease. Here, we describe a recurrent gene rearrangement in type B2 + B3 thymomas. PATIENTS AND METHODS: A single index case of thymoma was evaluated by an RNA-based solid fusion assay. Separately, tissues from 255,008 unique advanced cancers, including 242 thymomas, were sequenced by hybrid capture-based next-generation DNA sequencing/comprehensive genomic profiling of 186 to 406 genes, including lysine methyltransferase 2A (KMT2A) rearrangements, and a portion were evaluated for RNA of 265 genes. We characterized molecular and clinicopathologic features of the pertinent fusion-positive patient cases. RESULTS: We identified 11 patients with thymomas harboring a gene fusion of KMT2A and mastermind-like transcriptional coactivator 2 (MAML2). Fusion breakpoints were identified between exon 8, 9, 10, or 11 of KMT2A and exon 2 of MAML2. Fifty-five percent were men, with a median age of 48 years at surgery (range, 29-69 years). Concurrent genomic alterations were infrequent. The 11 thymomas were of B2 or B3 type histology, with 1 case showing foci of thymic carcinoma. The frequency of KMT2A-MAML2 fusion was 4% of all thymomas (10 of 242) and 6% of thymomas of B2 or B3 histology (10 of 169). CONCLUSION: KMT2A-MAML2 represents the first recurrent fusion described in type B thymoma. The fusion seems to be specific to type B2 and B3 thymomas, the most aggressive histologic subtypes. The identification of this fusion offers insights into the biology of thymoma and may have clinical relevance for patients with disease refractory to conventional therapeutic modalities.

CYLD-mutant cylindroma-like basaloid carcinoma of the anus: a genetically and morphologically distinct class of HPV-related anal carcinoma.

Rare reports of anal carcinoma (AC) describe histologic resemblance to cutaneous cylindroma, but mutations in the tumor suppressor CYLD, the gene responsible for familial and sporadic cylindromas, have not been systematically investigated in AC. Here, we investigate CYLD-mutant AC, focusing on molecular correlates of distinct histopathology. Comprehensive genomic profiling (hybrid-capture-based DNA sequencing) was performed on 574 ACs, of which 75 unique cases (13%) harbored a CYLD mutation. Clinical data, pathology reports, and histopathology were reviewed for each CYLD-mutant case. The spectrum of CYLD mutations included truncating (n = 50; 67%), homozygous deletion (n = 10; 13%), missense (n = 16; 21%), and splice-site (n = 3; 4%) events. Compared with CYLD-wildtype AC (n = 499), CYLD-mutant ACs were significantly enriched for females (88% vs. 67%, p = 0.0001), slightly younger (median age 59 vs. 61 years, p = 0.047), and included near-universal detection of high-risk HPV sequences (97% vs. 88%, p = 0.014), predominantly HPV16 (96%). The CYLD-mutant cohort also showed significantly lower tumor mutational burden (TMB; median 2.6 vs. 5.2 mut/Mb, p < 0.00001) and less frequent alterations in PIK3CA (13% vs. 31%, p = 0.0015). On histopathologic examination, 73% of CYLD-mutant AC (55/75 cases) showed a striking cylindroma-like histomorphology, composed of aggregates of basaloid cells surrounded by thickened basement membranes and containing characteristic hyaline globules, while only 8% of CYLD-wildtype tumors (n = 34/409) contained cylindroma-like hyaline globules (p < 0.0001). CYLD-mutant carcinomas with cylindroma-like histomorphology (n = 55) showed significantly lower TMB compared with CYLD-mutant cases showing basaloid histology without the distinctive hyaline globules (n = 14) (median 1.7 vs. 4.4 mut/Mb, p = 0.0058). Only five CYLD-mutant cases (7%) showed nonbasaloid conventional squamous cell carcinoma histology (median TMB = 5.2 mut/Mb), and a single CYLD-mutant case showed transitional cell carcinoma-like histology. Within our cohort of ACs, CYLD mutations characterize a surprisingly large subset (13%), with distinct clinical and genomic features and, predominantly, a striking cylindroma-like histopathology, representing a genotype-phenotype correlation which may assist in classification of AC.

The maternal immune activation model uncovers a role for the Arx gene in GABAergic dysfunction in schizophrenia.

A hallmark feature of schizophrenia is altered high frequency neural oscillations, including reduced auditory-evoked gamma oscillatory power, which is underpinned by parvalbumin (PV) interneuron dysfunction. Maternal immune activation (MIA) in rodents models an environmental risk factor for schizophrenia and recapitulates these PV interneuron changes. This study sought to link reduced PV expression in the MIA model with alterations to auditory-evoked gamma oscillations and transcript expression. We further aligned transcriptional findings from the animal model with human genome sequencing data. We show that MIA, induced by the viral mimetic, poly-I:C in C57Bl/6 mice, caused in adult offspring reduced auditory-evoked gamma and theta oscillatory power paralleled by reduced PV protein levels. We then showed the Arx gene, critical to healthy neurodevelopment of PV interneurons, is reduced in the forebrain of MIA exposed mice. Finally, in a whole-genome sequenced patient cohort, we identified a novel missense mutation of ARX in a patient with schizophrenia and in the Psychiatric Genomics Consortium 2 cohort, a nominal association of proximal ARX SNPs with the disorder. This suggests MIA, as a risk factor for schizophrenia, may be influencing Arx expression to induce the GABAergic dysfunction seen in schizophrenia and that the ARX gene may play a role in the prenatal origins of schizophrenia pathophysiology.