Identifying genetic determinants of inflammatory pain in mice using a large-scale gene-targeted screen.

ABSTRACT: Identifying the genetic determinants of pain is a scientific imperative given the magnitude of the global health burden that pain causes. Here, we report a genetic screen for nociception, performed under the auspices of the International Mouse Phenotyping Consortium. A biased set of 110 single-gene knockout mouse strains was screened for 1 or more nociception and hypersensitivity assays, including chemical nociception (formalin) and mechanical and thermal nociception (von Frey filaments and Hargreaves tests, respectively), with or without an inflammatory agent (complete Freund's adjuvant). We identified 13 single-gene knockout strains with altered nocifensive behavior in 1 or more assays. All these novel mouse models are openly available to the scientific community to study gene function. Two of the 13 genes (Gria1 and Htr3a) have been previously reported with nociception-related phenotypes in genetically engineered mouse strains and represent useful benchmarking standards. One of the 13 genes (Cnrip1) is known from human studies to play a role in pain modulation and the knockout mouse reported herein can be used to explore this function further. The remaining 10 genes (Abhd13, Alg6, BC048562, Cgnl1, Cp, Mmp16, Oxa1l, Tecpr2, Trim14, and Trim2) reveal novel pathways involved in nociception and may provide new knowledge to better understand genetic mechanisms of inflammatory pain and to serve as models for therapeutic target validation and drug development.

Cross-Species Analyses Identify Dlgap2 as a Regulator of Age-Related Cognitive Decline and Alzheimer's Dementia.

Genetic mechanisms underlying age-related cognitive decline and dementia remain poorly understood. Here, we take advantage of the Diversity Outbred mouse population to utilize quantitative trait loci mapping and identify Dlgap2 as a positional candidate responsible for modifying working memory decline. To evaluate the translational relevance of this finding, we utilize longitudinal cognitive measures from human patients, RNA expression from post-mortem brain tissue, data from a genome-wide association study (GWAS) of Alzheimer's dementia (AD), and GWAS results in African Americans. We find an association between Dlgap2 and AD phenotypes at the variant, gene and protein expression, and methylation levels. Lower cortical DLGAP2 expression is observed in AD and is associated with more plaques and tangles at autopsy and faster cognitive decline. Results will inform future studies aimed at investigating the cross-species role of Dlgap2 in regulating cognitive decline and highlight the benefit of using genetically diverse mice to prioritize novel candidates.

T Cells from NOD-PerIg Mice Target Both Pancreatic and Neuronal Tissue.

It has become increasingly appreciated that autoimmune responses against neuronal components play an important role in type 1 diabetes (T1D) pathogenesis. In fact, a large proportion of islet-infiltrating B lymphocytes in the NOD mouse model of T1D produce Abs directed against the neuronal type III intermediate filament protein peripherin. NOD-PerIg mice are a previously developed BCR-transgenic model in which virtually all B lymphocytes express the H and L chain Ig molecules from the intra-islet-derived anti-peripherin-reactive hybridoma H280. NOD-PerIg mice have accelerated T1D development, and PerIg B lymphocytes actively proliferate within islets and expand cognitively interactive pathogenic T cells from a pool of naive precursors. We now report adoptively transferred T cells or whole splenocytes from NOD-PerIg mice expectedly induce T1D in NOD.scid recipients but, depending on the kinetics of disease development, can also elicit a peripheral neuritis (with secondary myositis). This neuritis was predominantly composed of CD4+ and CD8+ T cells. Ab depletion studies showed neuritis still developed in the absence of NOD-PerIg CD8+ T cells but required CD4+ T cells. Surprisingly, sciatic nerve-infiltrating CD4+ cells had an expansion of IFN-γ- and TNF-α- double-negative cells compared with those within both islets and spleen. Nerve and islet-infiltrating CD4+ T cells also differed by expression patterns of CD95, PD-1, and Tim-3. Further studies found transitory early B lymphocyte depletion delayed T1D onset in a portion of NOD-PerIg mice, allowing them to survive long enough to develop neuritis outside of the transfer setting. Together, this study presents a new model of peripherin-reactive B lymphocyte-dependent autoimmune neuritis.

Functional rescue in a mouse model of congenital muscular dystrophy with megaconial myopathy.

Congenital muscular dystrophy with megaconial myopathy (MDCMC) is an autosomal recessive disorder characterized by progressive muscle weakness and wasting. The observation of megamitochondria in skeletal muscle biopsies is exclusive to this type of MD. The disease is caused by loss of function mutations in the choline kinase beta (CHKB) gene which results in dysfunction of the Kennedy pathway for the synthesis of phosphatidylcholine. We have previously reported a rostrocaudal MD (rmd) mouse with a deletion in the Chkb gene resulting in an MDCMC-like phenotype, and we used this mouse to test gene therapy strategies for the rescue and alleviation of the dystrophic phenotype. Introduction of a muscle-specific Chkb transgene completely rescues motor and behavioral function in the rmd mouse model, confirming the cell-autonomous nature of the disease. Intramuscular gene therapy post-disease onset using an adeno-associated viral 6 (AAV6) vector carrying a functional copy of Chkb is also capable of rescuing the dystrophy phenotype. In addition, we examined the ability of choline kinase alpha (Chka), a gene paralog of Chkb, to improve dystrophic phenotypes when upregulated in skeletal muscles of rmd mutant mice using a similar AAV6 vector. The sum of our results in a preclinical model of disease suggest that replacement of the Chkb gene or upregulation of endogenous Chka could serve as potential lines of therapy for MDCMC patients.

Assessing Healthspan and Lifespan Measures in Aging Mice: Optimization of Testing Protocols, Replicability, and Rater Reliability.

The relationship between chronological age (lifespan) and biological age (healthspan) varies amongst individuals. Understanding the normal trajectory and characteristic traits of aging mice throughout their lifespan is important for selecting the most reliable and reproducible measures to test hypotheses. The protocols herein describe assays used for aging studies at The Jackson Laboratory's Mouse Neurobehavioral Phenotyping Facility and include assessments of frailty, cognition, and sensory (hearing, vision, olfaction), motor, and fine motor function that can be used for assessing phenotypes in aged mice across their lifespan as well as provide guidance for setting up and validating these behavioral measures. Researchers aiming to study aging phenotypes require access to aged mice as a reference when initiating these types of studies in order to observe normal aging characteristics that cannot be observed in young adult mouse populations. © 2018 by John Wiley & Sons, Inc.

Biallelic mutations in the ferredoxin reductase gene cause novel mitochondriopathy with optic atrophy.

Iron-sulfur (Fe-S) clusters are ubiquitous cofactors essential to various cellular processes, including mitochondrial respiration, DNA repair, and iron homeostasis. A steadily increasing number of disorders are being associated with disrupted biogenesis of Fe-S clusters. Here, we conducted whole-exome sequencing of patients with optic atrophy and other neurological signs of mitochondriopathy and identified 17 individuals from 13 unrelated families with recessive mutations in FDXR, encoding the mitochondrial membrane-associated flavoprotein ferrodoxin reductase required for electron transport from NADPH to cytochrome P450. In vitro enzymatic assays in patient fibroblast cells showed deficient ferredoxin NADP reductase activity and mitochondrial dysfunction evidenced by low oxygen consumption rates (OCRs), complex activities, ATP production and increased reactive oxygen species (ROS). Such defects were rescued by overexpression of wild-type FDXR. Moreover, we found that mice carrying a spontaneous mutation allelic to the most common mutation found in patients displayed progressive gait abnormalities and vision loss, in addition to biochemical defects consistent with the major clinical features of the disease. Taken together, these data provide the first demonstration that germline, hypomorphic mutations in FDXR cause a novel mitochondriopathy and optic atrophy in humans.

Political rhetoric from Canada can inform healthy public policy argumentation.

Household food insecurity (HFI), insufficient income to obtain adequate food, is a growing problem in Canada and other Organisation of economic cooperation and development (OECD) countries. Government political orientations impact health policies and outcomes. We critically examined Canadian political rhetoric around HFI from 1995 to 2012 as a means to support effective healthy public policy argumentation. We analysed a data set comprised of Hansard extracts on HFI from the legislative debates of the Canadian federal and three provincial governments, using thematic coding guided by interpretivist theories of policy. Extracts were examined for content, jurisdiction, the political affiliation of the legislator speaking and governing status. Members of non-governing, or 'opposition' parties, dominated the rhetoric. A central hunger-as-poverty theme was used by legislators across the political spectrum, both in government and in opposition. Legislators differed in terms of policy approach around how income should flow to citizens facing HFI: income intervention on the left, pragmatism in the centre, reliance on markets on the right. This analysis is a case-example from Canada and caution must be exercised in terms of the generalizability of findings across jurisdictions. Despite this limitation, our findings can help healthy public policy advocates in designing and communicating HFI policy interventions in OECD countries with a similar left-right spectrum. First, even with a divisive health policy issue such as actions to address HFI, core themes around poverty are widely understood. Secondly, the non-polarizing centrist, pragmatist, approach may be strategically valuable. Thirdly, it is important to treat the rhetoric of opposition members differently from that of government members.

Reprint of "Biological motion perception links diverse facets of theory of mind during middle childhood".

Two cornerstones of social development-social perception and theory of mind-undergo brain and behavioral changes during middle childhood, but the link between these developing domains is unclear. One theoretical perspective argues that these skills represent domain-specific areas of social development, whereas other perspectives suggest that both skills may reflect a more integrated social system. Given recent evidence from adults that these superficially different domains may be related, the current study examined the developmental relation between these social processes in 52 children aged 7 to 12years. Controlling for age and IQ, social perception (perception of biological motion in noise) was significantly correlated with two measures of theory of mind: one in which children made mental state inferences based on photographs of the eye region of the face and another in which children made mental state inferences based on stories. Social perception, however, was not correlated with children's ability to make physical inferences from stories about people. Furthermore, the mental state inference tasks were not correlated with each other, suggesting a role for social perception in linking various facets of theory of mind.

Biological motion perception links diverse facets of theory of mind during middle childhood.

Two cornerstones of social development--social perception and theory of mind--undergo brain and behavioral changes during middle childhood, but the link between these developing domains is unclear. One theoretical perspective argues that these skills represent domain-specific areas of social development, whereas other perspectives suggest that both skills may reflect a more integrated social system. Given recent evidence from adults that these superficially different domains may be related, the current study examined the developmental relation between these social processes in 52 children aged 7 to 12 years. Controlling for age and IQ, social perception (perception of biological motion in noise) was significantly correlated with two measures of theory of mind: one in which children made mental state inferences based on photographs of the eye region of the face and another in which children made mental state inferences based on stories. Social perception, however, was not correlated with children's ability to make physical inferences from stories about people. Furthermore, the mental state inference tasks were not correlated with each other, suggesting a role for social perception in linking various facets of theory of mind.

Aging Research Using Mouse Models.

Despite the dramatic increase in human lifespan over the past century, there remains pronounced variability in "health-span," or the period of time in which one is generally healthy and free of disease. Much of the variability in health-span and lifespan is thought to be genetic in origin. Understanding the genetic mechanisms of aging and identifying ways to boost longevity is a primary goal in aging research. Here, we describe a pipeline of phenotypic assays for assessing mouse models of aging. This pipeline includes behavior/cognition testing, body composition analysis, and tests of kidney function, hematopoiesis, and immune function, as well as physical parameters. We also describe study design methods for assessing lifespan and health-span, and other important considerations when conducting aging research in the laboratory mouse. The tools and assays provided can assist researchers with understanding the correlative relationships between age-associated phenotypes and, ultimately, the role of specific genes in the aging process.

Sex and strain influence attribution of incentive salience to reward cues in mice.

The propensity to attribute incentive salience to reward cues, measured by Pavlovian sign-tracking, is strongly associated with addiction-related traits including cocaine self-administration, impulsivity, novelty reactivity, and novelty preference. Despite its critical role in addiction, the genetic underpinnings of incentive salience attribution and its relationship to drug addiction are unknown. Mouse genetics can be a powerful means to discover genetic mechanisms underlying this relationship. However, feasibility of genetic dissection of sign-tracking in mice is unknown as only a single study limited to male C57BL/6J mice has rigorously examined this behavior, and limited sign-tracking was observed. Highly diverse mouse populations such as the Collaborative Cross (CC) and Diversity Outbred population (DO) possess a greater range of behavioral and genetic variation than conventional laboratory strains. In the present study, we evaluated sign-tracking and the related phenotype goal-tracking in mice of both sexes from five inbred CC and DO founder strains. Male CAST/EiJ mice exhibited robust sign-tracking; male NOD, male C57BL/6J, and female A/J mice also exhibited significant sign-tracking. Male and female mice from all strains exhibited significant goal-tracking, and significant strain and sex differences were observed. Sign-tracking in males was genetically correlated with exploration of a novel environment, and heritability of sign-tracking and goal-tracking ranged from .32 to .41. These data highlight the importance of considering genetic diversity when evaluating the occurrence of specific behavioral traits in the laboratory mouse and demonstrate that the CC and DO mouse populations can be used to discover mechanisms underlying genetic relationships among sign-tracking and addiction-related behaviors.

Dissociating the Neural Correlates of Experiencing and Imagining Affective Touch.

This functional magnetic resonance imaging (fMRI) study examined experiencing and imagining gentle arm and palm touch to determine whether these processes activate overlapping or distinct brain regions. Although past research shows brain responses to experiencing and viewing touch, this study investigates neural processing of touch absent of visual stimulation. C-tactile (CT) nerves, present in hairy skin, respond specifically to caress-like touch. CT-targeted touch activates "social brain" regions including insula, right posterior superior temporal sulcus, amygdala, temporal poles, and orbitofrontal cortex ( McGlone et al. 2012). We addressed whether activations reflect sensory input-driven mechanisms, cognitive-based mechanisms, or both. We identified a functional dissociation between insula regions. Posterior insula responded during experienced touch. Anterior insula responded during both experienced and imagined touch. To isolate stimulus-independent mechanisms recruited during physical experience of CT-targeted touch, we identified regions active to experiencing and imagining such touch. These included amygdala and temporal pole. We posit that the dissociation of insula function suggests posterior and anterior insula involvement in distinct yet interacting processes: coding physical stimulation and affective interpretation of touch. Regions active during experiencing and imagining CT-targeted touch are associated with social processes indicating that imagining touch conjures affective aspects of experiencing such touch.

Tracking the Neurodevelopmental Correlates of Mental State Inference in Early Childhood.

Between ages 4 and 6, children become better at inferring what others are thinking and feeling. However, the neural correlates of these advances are understudied. The current study investigated the relation between performance on a face-based mental state inference task and white matter characteristics. Two tracts of interest, the uncinate fasciculus (UF) and inferior longitudinal fasciculus, were analyzed due to their involvement in social-emotional and face processing, respectively. Findings demonstrate a significant relation between fractional anisotropy in the UF and task performance in 4- but not 6-year-old children. Findings have implications for typical and atypical populations.

Improvements in social and adaptive functioning following short-duration PRT program: a clinical replication.

Pivotal Response Treatment (PRT) is an empirically validated behavioral treatment for individuals with autism spectrum disorders (ASD). The purpose of the current study was to assess the efficacy of PRT for ten cognitively-able preschool-aged children with ASD in the context of a short-duration (4-month) treatment model. Most research on PRT used individual behavioral goals as outcome measures, but the current study utilized standardized assessments of broader-based social communication and adaptive skills. The children made substantial gains; however, magnitude and consistency of response across measures were variable. The results provide additional support for the efficacy of PRT as well as evidence for improvements in higher-order social communication and adaptive skill development within the context of a short-duration PRT model.

fNIRS detects temporal lobe response to affective touch.

Touch plays a crucial role in social-emotional development. Slow, gentle touch applied to hairy skin is processed by C-tactile (CT) nerve fibers. Furthermore, 'social brain' regions, such as the posterior superior temporal sulcus (pSTS) have been shown to process CT-targeted touch. Research on the development of these neural mechanisms is scant, yet such knowledge may inform our understanding of the critical role of touch in development and its dysfunction in disorders involving sensory issues, such as autism. The aim of this study was to validate the ability of functional near-infrared spectroscopy (fNIRS), an imaging technique well-suited for use with infants, to measure temporal lobe responses to CT-targeted touch. Healthy adults received brushing to the right forearm (CT) and palm (non-CT) separately, in a block design procedure. We found significant activation in right pSTS and dorsolateral prefrontal cortex to arm > palm touch. In addition, individual differences in autistic traits were related to the magnitude of peak activation within pSTS. These findings demonstrate that fNIRS can detect brain responses to CT-targeted touch and lay the foundation for future work with infant populations that will characterize the development of brain mechanisms for processing CT-targeted touch in typical and atypical populations.

Brain mechanisms of plasticity in response to treatments for core deficits in autism.

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by social communication impairments and repetitive behaviors. Although the prevalence of ASD is estimated at 1 in 88, understanding of the neural mechanisms underlying the disorder is still emerging. Regions including the amygdala, superior temporal sulcus, orbitofrontal cortex, fusiform gyrus, medial prefrontal cortex, and insula have been implicated in social processing. Neuroimaging studies have demonstrated both anatomical and functional differences in these areas of the brain in individuals with ASD when compared to controls; however, research on the neural basis for response to treatment in ASD is limited. Results of the three studies that have examined the neural mechanisms underlying treatment response are promising; following treatment, the brains of individuals with ASD seem to "normalize," responding more similarly to those of typically developing individuals. The research in this area is in its early stages, and thus a focused effort examining the neural basis of treatment response in ASD is crucial.

Food insecurity, childhood illness and maternal emotional distress in Ethiopia.

OBJECTIVE: The relationship between food insecurity, maternal emotional distress and childhood morbidity in resource-poor settings is not well clarified. The present study aimed to assess independent associations between household food insecurity and childhood morbidity and potential modifications by maternal emotional distress. DESIGN: A cross-sectional survey. A food security scale was used to assess household food insecurity; maternal reports were used to assess recent childhood illness; and the Hopkins Symptom Checklist was used to assess symptoms of emotional distress among mothers. SETTING: The Oromia Region, Ethiopia (rural area). SUBJECTS: A total of 936 mother-child pairs. RESULTS: Of 936 children assessed, 22·4% had experienced diarrhoea, 20·7% had cough and 21·5% had fever in the 2 weeks preceding the interview. Household food insecurity was reported by 39% of mothers. Greater food insecurity and greater maternal emotional distress were each independently associated with higher prevalence of cough and fever. Among mothers with low emotional distress, food insecurity was associated with a 2·3 times greater odds of diarrhoea in their children. CONCLUSIONS: Household food insecurity may increase the risk of childhood illness in rural Ethiopia, and children having mothers with greater emotional distress may be at highest risk. These findings highlight the importance of strengthening policy initiatives aimed at reducing the high prevalence of food insecurity and emotional distress in Ethiopia.