Systematic functional analysis of Leishmania protein kinases identifies regulators of differentiation or survival

Differentiation between distinct stages is fundamental for the life cycle of intracellular protozoan parasites and for transmission between hosts, requiring stringent spatial and temporal regulation. Here, we apply kinome-wide gene deletion and gene tagging in Leishmania mexicana promastigotes to define protein kinases with life cycle transition roles. Whilst 162 are dispensable, 44 protein kinase genes are refractory to deletion in promastigotes and are likely core genes required for parasite replication. Phenotyping of pooled gene deletion mutants using bar-seq and projection pursuit clustering reveal functional phenotypic groups of protein kinases involved in differentiation from metacyclic promastigote to amastigote, growth and survival in macrophages and mice, colonisation of the sand fly and motility. This unbiased interrogation of protein kinase function in Leishmania allows targeted investigation of organelle-associated signalling pathways required for successful intracellular parasitism.

Cholesterol 25-hydroxylase (CH25H) as a promoter of adipose tissue inflammation in obesity and diabetes

Objective

Expansion of visceral adipose tissue (VAT) and metabolic inflammation are consequences of obesity and associated with type 2 diabetes (T2DM). Metabolically activated adipose tissue macrophages (ATMs) undergo qualitative and quantitative changes that influence their inflammatory responses. How these cells contribute to insulin resistance (IR) in humans is not well understood. Cholesterol 25-Hydroxylase (CH25H) converts cholesterol into 25-Hydroxycholesterol (25-HC), an oxysterol that modulates immune responses. Using human and murine models, we investigated the role of CH25H in metabolic inflammation.

Methods

We performed transcriptomic (RNASeq) analysis on the human whole AT biopsies and sorted ATMs from obese non-diabetic (NDM) and obese diabetic (DM) subjects to inquire if CH25H was increased in DM. We challenged mice lacking Ch25h with a high-fat diet (HFD) to characterize their metabolic and immunologic profiling. Ch25h KO mice and human adipose tissue biopsies from NDM and DM subjects were analyzed. LC-MS was conducted to measure 25-HC level in AT. In vitro analysis permitted us to investigate the effect of 25-HC on cytokine expression.

Results

In our RNASeq analysis of human visceral and subcutaneous biopsies, gene pathways related to inflammation were increased in obese DM vs. non-DM subjects that included CH25H. CH25H was enriched in the stromal vascular fraction of human adipose tissue and highly expressed in CD206⁺ human ATMs by flow cytometry analysis. We measured the levels of the oxysterols, 25-HC and 7α25diHC, in human visceral adipose tissue samples and showed a correlation between BMI and 25-HC. Using mouse models of diet-induced obesity (DIO), we found that HFD-induced Ch25h expression in eWAT and increased levels of 25-HC in AT. On HFD, Ch25h KO mice became obese but exhibited reduced plasma insulin levels, improved insulin action, and decreased ectopic lipid deposit. Improved insulin sensitivity in Ch25h KO mice was due to attenuation of CD11c⁺ adipose tissue macrophage infiltration in eWAT. Finally, by testing AT explants, bone marrow-derived macrophages (BMDMs) and SVF cells from Ch25h deficient mice, we observed that 25-HC is required for the expression of pro-inflammatory genes. 25-HC was also able to induce inflammatory genes in preadipocytes.

Conclusions

Our data suggest a critical role for CH25H/25-HC in the progression of meta-inflammation and insulin resistance in obese humans and mouse models of obesity. In response to obesogenic stimuli, CH25H/25-HC could exert a pro-inflammatory role.

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CH25H upregulation in visceral adipose tissue is associated with diabetes in humans.

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ATMs are the primary site of CH25H expression in humans and mice.

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DIO in mice activates Ch25h expression and 25-HC production in visceral adipose tissue.

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Obese Ch25h KO mice have improved insulin sensitivity due to attenuated adipose tissue inflammation.

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In response to inflammatory stimuli, Ch25h/25-HC potentiates myeloid activation.

Pre-frailty factors in community-dwelling 40-75 year olds: opportunities for successful ageing

BACKGROUND

There is little known about pre-frailty attributes or when changes which contribute to frailty might be detectable and amenable to change. This study explores pre-frailty and frailty in independent community-dwelling adults aged 40-75 years.

METHODS

Participants were recruited through local council networks, a national bank and one university in Adelaide, Australia. Fried frailty phenotype scores were calculated from measures of unintentional weight loss, exhaustion, low physical activity levels, poor hand grip strength and slow walking speed. Participants were identified as not frail (no phenotypes), pre-frail (one or two phenotypes) or frail (three or more phenotypes). Factor analysis was applied to binary forms of 25 published frailty measures Differences were tested in mean factor scores between the three Fried frailty phenotypes and ROC curves estimated predictive capacity of factors.

RESULTS

Of 656 participants (67% female; mean age 59.9 years, SD 10.6) 59.2% were classified as not frail, 39.0% pre-frail and 1.8% frail. There were no gender or age differences. Seven frailty factors were identified, incorporating all 25 frailty measures. Factors 1 and 7 significantly predicted progression from not-frail to pre-frail (Factor 1 AUC 0.64 (95%CI 0.60-0.68, combined dynamic trunk stability and lower limb functional strength, balance, foot sensation, hearing, lean muscle mass and low BMI; Factor 7 AUC 0.55 (95%CI 0.52-0.59) comprising continence and nutrition. Factors 3 and 4 significantly predicted progression from pre-frail to frail (Factor 3 AUC 0.65 (95% CI 0.59-0.70)), combining living alone, sleep quality, depression and anxiety, and lung function; Factor 4 AUC 0.60 (95%CI 0.54-0.66) comprising perceived exertion on exercise, and falls history.

CONCLUSIONS

This research identified pre-frailty and frailty states in people aged in their 40s and 50s. Pre-frailty in body systems performance can be detected by a range of mutable measures, and interventions to prevent progression to frailty could be commenced from the fourth decade of life.

Abstract A08: Human preadipocytes promote pancreatic cancer cellular growth in a diabetes-specific manner

Objective: Type 2 diabetes mellitus (DM) is a known risk factor for pancreatic ductal adenocarcinoma (PDAC), but the mechanisms underlying this association remain poorly understood. Multiple reports implicate adipocytes and preadipocytes as putative promoters of PDAC in humans and mice. To test whether preadipocytes regulate PDAC tumorigenic functions in the context of DM, we explored the effects of conditioned media (CM) prepared from preadipocytes from nondiabetic (NDM) and DM patients on PDAC cells.

Methods: Preadipocytes were isolated from omental adipose tissue obtained from NDM and DM patients undergoing bariatric surgery. Serum-free conditioned media was prepared from these preadipocytes cultured in vitro for 72 hours. Sphere assays using T3M4 and Capan1 PDAC lines were performed in the presence or absence of conditioned media, and sphere surface area was measured over 2-3 weeks. Modifications of the sphere assays, including boiling of conditioned media as well as addition of neutralizing antibodies or recombinant proteins, were implemented. A proteome profiler array was used to identify differences in cytokine composition between CM from DM and NDM. A phospho-kinome array was used to identify differentially activated signaling pathways when PDAC cells were treated with NDM and DM conditioned media.

Results: Conditioned media from human DM preadipocytes, compared to media from NDM preadipocytes, increased PDAC cell sphere surface area in both T3M4 and Capan1 cell lines. Sphere surface area correlated directly with hemoglobin A1c (HbA1c) but not sex or body mass index of the human subjects from which preadipocytes were derived. Boiling of preadipocyte supernatants abrogated their pro-growth effects. Proteome profiler array analysis identified different proteins that were differentially expressed by DM and NDM preadipocytes, among which chitinase-3-like protein 1 (CHI3L1) and interleukin-6 (IL-6) were increased over 2-fold in DM relative to NDM preadipocyte supernatants. Neutralizing antibody to human CHI3L1 and IL-6 attenuated the increase in PDAC sphere surface area in response to DM preadipocyte conditioned media in a dose-dependent manner. Recombinant human CHI3L1 and IL-6 enhanced the growth of PDAC cells when they were exposed to NDM conditioned media. Phospho-kinome analysis demonstrated that treatment of PDAC cells with DM-derived conditioned media increased activation of inflammation-associated signal transduction pathways.

Conclusions: Preadipocyte-PDAC cell crosstalk regulates PDAC cell growth in a DM-specific and CHI3L1 and IL-6-dependent manner. These results suggest that the positive clinical correlation between DM and PDAC may be mediated by preadipocytes expressing higher levels of CHI3L1 and IL-6. Preadipocytes CHI3L1 and IL-6 represent targets for further research directed towards developing novel therapies for PDAC based on manipulation of the tumor microenvironment.

Citation Format: Lawrence Delrosario, Carmen Flesher, Nicki Baker, Jenny Lazarus, Mirna Perusina-Lanfranca, Robert O'Rourke, Timothy Frankel. Human preadipocytes promote pancreatic cancer cellular growth in a diabetes-specific manner [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr A08.

Health assessments and screening tools for adults experiencing homelessness: a systematic review

Background

Homelessness is increasing globally. It results in poorer physical and mental health than age matched people living in permanent housing. Better information on the health needs of people experiencing homelessness is needed to inform effective resourcing, planning and service delivery by government and care organisations.

The aim of this review was to identify assessment tools that are valid, reliable and appropriate to measure the health status of people who are homeless.

Methods

Data sources: A systematic literature search was conducted in PubMed (and Medline), PsychInfo, Scopus, CINAHL and ERIC from database inception until September 2018. Key words used were homeless, homelessness, homeless persons, vagrancy, health status, health, health issues, health assessment and health screening. The protocol was registered with PROSPERO. The National Health and Medical Research Council of Australia (NHMRC) hierarchy of evidence was applied; methodological quality of included articles was assessed using the McMaster critical appraisal tools and psychometric properties of the tools were appraised using the International Centre for Allied Health Evidence Ready Reckoner.

Results

Diverse tools and measures (N = 71) were administered within, and across the reviewed studies (N = 37), with the main focus being on general health, oral health and nutrition. Eleven assessment tools in 13 studies had evidence of appropriate psychometric testing for the target population in domains of quality of life and health status, injury, substance use, mental health, psychological and cognitive function. Methodological quality of articles and tools were assessed as moderate to good. No validated tools were identified to assess oral health, chronic conditions, anthropometry, demography, nutrition, continence, functional decline and frailty, or vision and hearing. However, assessments of physical constructs (such as oral health, anthropometry, vision and hearing) could be applied to homeless people on a presumption of validity, because the constructs would be measured with clinical indicators in the same manner as people living in permanent dwellings.

Conclusions

This review highlighted the need to develop consistent and comprehensive health assessment tools validated with, and tailored for, adults experiencing homelessness.

Electronic supplementary material

The online version of this article (10.1186/s12889-019-7234-y) contains supplementary material, which is available to authorized users.

Smoking in pregnancy is a key factor for sudden infant death among Māori

AIM

To examine the sudden unexpected death in infancy (SUDI) disparity between Māori and non-Māori in New Zealand.

METHODS

A nationwide prospective case-control study ran from March 2012 to February 2015. Exposure to established SUDI risk factors was analysed to investigate the disparity experienced by Māori. Infant ethnicity was based on mother's ethnicity. Māori ethnicity was prioritised. Non-Māori includes Pacific, Asian, NZ European and Other.

RESULTS

There were 137 cases and 649 controls. The Māori SUDI rate was 1.41/1000 live births compared to 0.53/1000 for non-Māori. Parents/caregivers of 132 cases (96%) and 258 controls (40%) were interviewed. Smoking in pregnancy was associated with an equally increased SUDI risk for Māori (adjusted OR = 8.11, 95% CI = 2.64, 24.93) and non-Māori (aOR = 5.09, 95% CI = 1.79, 14.47), as was bed-sharing (aOR = 3.66, 95% CI = 1.49, 9.00 vs aOR = 11.20, 95% CI = 3.46, 36.29). Bed-sharing prevalence was similar; however, more Māori controls smoked during pregnancy (46.7%) than non-Māori (22.8%). The main contributor relating to increased SUDI risk for Māori/non-Māori infants is the combination of smoking in pregnancy and bed sharing.

CONCLUSION

The association between known SUDI risk factors, including bed sharing and/or smoking in pregnancy and SUDI risk, is the same regardless of ethnicity. Māori infants are exposed more frequently to both behaviours because of the higher Māori smoking rate.

Evaluation of androgen assay results using a curated Hershberger database

A set of 39 reference chemicals with reproducible androgen pathway effects in vivo, identified in the companion manuscript [1], were used to interrogate the performance of the ToxCast/Tox 21 androgen receptor (AR) model based on 11 high throughput assays. Cytotoxicity data and specificity confirmation assays were used to distinguish assay loss-of-function from true antagonistic signaling suppression. Overall agreement was 66% (19/29), with ten additional inconclusive chemicals. Most discrepancies were explained using in vitro to in vivo extrapolation to estimate equivalent administered doses. The AR model had 100% positive predictive value for the in vivo response, i.e. there were no false positives, and chemicals with conclusive AR model results (agonist or antagonist) were consistently positive in vivo. Considering the lack of reproducibility of the in vivo Hershberger assay, the in vitro AR model may better predict specific AR interaction and can rapidly and cost-effectively screen thousands of chemicals without using animals.

Development of a curated Hershberger database

A systematic literature review was conducted to identify Hershberger bioassays for ∼3200 chemicals including those used to validate the OECD/US EPA guideline assay, US EPA's chemicals screened for endocrine activity, and the library of chemicals run in US EPA 's ToxCast in vitro assays. For 134 chemicals that met pre-defined criteria, experimental results were extracted into a database used to characterize uncertainty in results and evaluate the concordance of the Hershberger assay with other in vivo rodent studies that measure androgen-responsive endpoints. Of 25 chemicals tested in >1 Hershberger study, 28% had disagreements between studies (i.e. ≥1 positive and ≥1 negative study), and of the 65 chemicals tested in Hershberger studies and other in vivo studies with androgen-responsive endpoints, 43% indicated disagreements, though in some cases these may be explained by differences in study designs or physiology of the animal model. Ultimately, 49 chemicals were identified with reproducible androgen pathway responses confirmed in ≥2 in vivo rodent studies that could be considered reference chemicals useful for validating alternative methods.

The continued emergence of hantaviruses: isolation of a Seoul virus implicated in human disease, United Kingdom, October 2012

Following a suspected case of hantavirus in a patientsuffering from acute kidney injury, rodents fromthe patient’s property in Yorkshire and the Humber,United Kingdom (UK) were screened for hantaviruses.Hantavirus RNA was detected via RT-PCR in two Rattusnorvegicus. Complete sequencing and phylogeneticanalysis established the virus as a Seoul hantavirus,which we have provisionally designated as strainHumber. This is the first hantavirus isolated from wildrodents in the UK and confirms the presence of a pathogenicSeoul virus in Europe.

The continued emergence of hantaviruses: isolation of a Seoul virus implicated in human disease, United Kingdom, October 2012

Binary file ES_Abstracts_Final_ECDC.txt matches

Method for assessing IFN-γ responses in guinea pigs during TB vaccine trials

AIMS

We sought to develop a new method that enables the assessment of the immune response of guinea pigs during TB vaccine evaluation studies, without the need to cull or anaesthetize animals.

METHOD AND RESULTS

Guinea pigs were vaccinated with five different formulations of oral BCG. One week prior to challenge with Mycobacterium bovis, blood (50-200 μl) was taken from the ears of vaccinated subjects. Host RNA was isolated and amplified following antigenic restimulation of PBMCs for 24 h with 30 μg of bovine PPD. The up- or down-regulation of γ-interferon (IFN-γ), a key cytokine involved in protection against tuberculosis, was assessed using real-time PCR. The relative expression of prechallenge IFN-γ mRNA in the vaccinated groups (n=5) correlated (P<0·001) with protection against M. bovis challenge.

CONCLUSION

We have demonstrated that it is possible to take blood samples and track IFN-γ responses in guinea pigs that then go on to be exposed to M. bovis, thus providing prechallenge vaccine uptake information.

SIGNIFICANCE AND IMPACT OF THE STUDY

This methodology will also be applicable for tracking the immune responses of vaccinated guinea pigs over time that then go on to be challenged with M. tuberculosis during human TB vaccine evaluation studies.

Polychlorinated biphenyl 77 augments angiotensin II-induced atherosclerosis and abdominal aortic aneurysms in male apolipoprotein E deficient mice

Infusion of angiotensin II (AngII) to hyperlipidemic mice augments atherosclerosis and causes formation of abdominal aortic aneurysms (AAAs). Each of these AngII-induced vascular pathologies exhibit pronounced inflammation. Previous studies demonstrated that coplanar polychlorinated biphenyls (PCBs) promote inflammation in endothelial cells and adipocytes, two cell types implicated in AngII-induced vascular pathologies. The purpose of this study was to test the hypothesis that administration of PCB77 to male apolipoprotein E (ApoE) -/- mice promotes AngII-induced atherosclerosis and AAA formation. Male ApoE-/- mice were administered vehicle or PCB77 (49 mg/kg, i.p.) during week 1 and 4 (2 divided doses/week) of AngII infusion. Body weights and total serum cholesterol concentrations were not influenced by administration of PCB77. Systolic blood pressure was increased in AngII-infused mice administered PCB77 compared to vehicle (156±6 vs 137±5 mmHg, respectively). The percentage of aortic arch covered by atherosclerotic lesions was increased in AngII-infused mice administered PCB77 compared to vehicle (2.0±0.4 vs 0.9±0.1%, respectively). Lumen diameters of abdominal aortas determined by in vivo ultrasound and external diameters of excised suprarenal aortas were increased in AngII-infused mice administered PCB77 compared to vehicle. In addition, AAA incidence increased from 47 to 85% in AngII-infused mice administered PCB77. Adipose tissue in close proximity to AAAs from mice administered PCB77 exhibited increased mRNA abundance of proinflammatory cytokines and elevated expression of components of the renin-angiotensin system (angiotensinogen, angiotensin type 1a receptor (AT1aR)). These results demonstrate that PCB77 augments AngII-induced atherosclerosis and AAA formation.

Multiple Biomarker Expression in Circulating Tumor Cells (CTCs) from Metastatic Breast Cancer (MBC) Patients (Pts)

Background: Numeration of CTCs from MBC pts is predictive of outcome. Quantitative changes in CTC-s are currently tested for their potential to monitor therapy (Rx). Biomarker characterization of CTCs may be a useful adjunctive guide for Rx selection. Method: At the COHCC between 5/1/2008 and 4/31/09, consecutively treated pts with newly diagnosed/or progressing MBC were accrued. Blood samples (10-40 ml) were procured prior to or during systemic Rx, and were sent to PARC for analysis. A novel high-speed scanning instrument located CTCs from cytokeratin (CK) labeling enabling high resolution images to be selectively acquired using digital microscopy. From these images, CTCs were identified by CK, DAPI (nuclear marker) and CD45, and protein expression levels were determined for HER2, ER, ERCC1 and EGFR. Cell lines with expression of each marker were used for normalization of the cell intensities, and a scoring system was used to account for relative number and expression levels of markers on the CTCs. Results: Of 21pts tested 81% were found to have detectable CTCs. CTCs were further analyzed from 13 such pts, some of whom had multiple specimens. Expression of EGFR and ERCC1 were detected in 77% and 92% of specimens tested. Expression of HER2 was detected in 47% and ER in 91% in samples tested. Discordance rates for the expression of the above 4 markers on the primary tumors vs. CTC were measured either before, during systemic treatment, or at progression on therapy. We observed significant discordance rates for all markers tested:ER 36%; ERCC1:20%; EGFR:60%; and HER2: 50%, respectively. Conclusions: Multiplex tumor marker testing of CTCs from pts with MBC is feasible. Following additional validation of expression patterns and the high discordance rates observed between CTCs and primary or metastatic tumor sites, prospective trials incorporating CTC expression into personalized treatment strategies may be justified.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3007.

Barriers to Treatment in Patients with Locally Advanced and Inflammatory Breast Cancer

Background: Breast cancer in the United States will affect approximately one in eight women. Despite a decrease in breast cancer mortality due to increased awareness and more effective screening, many patients still present for treatment after extended delays in diagnosis, resulting in large tumor size, locally advanced disease, inflammatory features, and greater likelihood of regional and distant metastasis. The purpose of this study was to identify reasons why patients may encounter delays in obtaining a diagnosis, seeking medical care, and initiating treatment once symptoms appear.Methods: From 12/2006 through 5/2009, a questionnaire was administered to thirty-four consecutive patients who presented to our institution with histologically-verified stage III breast cancer who had experienced a 3-month or greater delay in diagnosis and initiation of treatment from time of onset of symptoms. The 39-item Likert-scale questionnaire was developed to explore perceived barriers. Responses were rated on a scale of "Strongly Agree" through "Strongly Disagree," relative to the barriers presented.Results: The median age of patients who completed the questionnaire was 52 years (range, 30 to 78 years). Of these, there were 29.4% White/Non-Hispanic, 52.9% White/Hispanic, 11.8% Black and 5.9% Asians. For 73.5% of patients, the diagnosis of breast cancer was made at an outside institution. Most of the participants were diagnosed with locally advanced infiltrating ductal carcinoma (82.4%) and 8.8% were diagnosed with inflammatory breast cancer. Barriers to treatment were divided into the following categories:Patient barriers: The most commonly reported barrier among respondants was "waiting for the scheduled visit to get results." (47.1% with a response of Agree or Strongly Agree) However, 35.2% of patients did not seek treatment because they were concerned about losing their breast. More than a third of patients delayed care because of perception that their breast symptoms were due to infection, muscle strain, or related to their menstrual cycle (35.3%). For 27.6% of respondants, no care was sought because of perception that their breast symptoms would resolve with time. Other barriers, such as access to transportation,, inconvenient physician office hours, child care problems and inability to take time off from work, continued to be present but were not as frequently reported (less than 20%).Physician barriers: Approximately one fourth of women reported that their physician of initial contact, did not believe that their breast lump/symptom was related to cancer (23.5%).System barriers: Among systems barriers, "delay in scheduling diagnostic tests" remained the most prevalent barrier to breast cancer treatment (38.2%).Conclusion: We observed substantial delays between symptom presentation and diagnosis in patients who came to seek therapy at a tertiary comprehensive cancer center (City Of Hope National Medical Center) in Southern California. Patients and physicians need to be educated on the importance of timely diagnostic tests and follow-up visits. In addition, studies are needed to better identify predictive factors for women at risk for encountering barriers to healthcare so that for these subpopulations, interventions can be implemented to reduce breast cancer morbidity and mortality.

Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 3084.

A chemiluminescence nanosensor to monitor lipid peroxidation

Coumarin C343 (C(16)H(15)NO(4)), a dye used to enhance the weak chemiluminescence associated with lipid peroxidation, was conjugated to silica nanoparticles and entrapped in a sol-gel matrix to produce a nanosensor capable of enhancing low-level chemiluminescence by approximately 100%.

Slc11a1 (formerly NRAMP1) gene modulates both acute inflammatory reactions and pristane-induced arthritis in mice

Mice selected for the maximum acute inflammatory reaction (AIRmax) are highly susceptible to pristane-induced arthritis (PIA), whereas mice selected for the minimum response (AIRmin) are resistant. These lines show distinct patterns of leukocyte infiltration and R and S allele frequency disequilibrium of the solute carrier family 11a member 1 (Slc11a1) gene. In order to study the interactions of the Slc11a1 R and S alleles with the inflammation modulating Quantitative Trait Loci (QTL) during PIA development, homozygous AIRmax(RR), AIRmax(SS), AIRmin(RR) and AIRmin(SS) lines were produced by genotype-assisted breedings. These mice received two intraperitoneal injections of 0.5 ml pristane at 60-day intervals, and the subsequent development of arthritis was assessed for 210 days. Cytokine-secreting cell profiles were investigated using enzyme-linked immunospot. Arthritis incidence in AIRmax(RR) mice reached 29%, whereas PIA incidence in AIRmax(SS) mice was 70% by day 180. AIRmin(RR) mice were resistant, whereas 13.3% of AIRmin(SS) mice became arthritic. The presence of the defective S allele also increased arthritis severity, although acute inflammation was higher in mice bearing the R allele. A predominant Th0/Th2-type response in Slc11a1(SS) mice was observed. These results indicate that Slc11a1 is a strong candidate for the QTL modulating acute inflammation and for PIA.

GAD1 (2q31.1), which encodes glutamic acid decarboxylase (GAD67), is associated with childhood-onset schizophrenia and cortical gray matter volume loss

Postmortem brain studies have shown deficits in the cortical gamma-aminobutyric acid (GABA) system in schizophrenic individuals. Expression studies have shown a decrease in the major GABA-synthesizing enzyme (glutamic acid decarboxylase (GAD67) mRNA levels in neurons in dorsolateral prefrontal cortex in schizophrenics relative to controls. In the present study, SNPs in and around the GAD1 gene, which encodes the protein GAD67, were tested on a rare, severely ill group of children and adolescents with childhood-onset schizophrenia (COS) (n=72), in a family-based association analysis. Compared to adult-onset samples, the COS sample has evidence for more salient familial, and perhaps genetic, risk factors for schizophrenia, as well as evidence for frontal cortical hypofunction, and greater decline in cortical gray matter volume on anatomic brain MRI scans during adolescence. We performed family-based TDT and haplotype association analyses of the clinical phenotype, as well as association analyses with endophenotypes using the QTDT program. Three adjacent SNPs in the 5' upstream region of GAD1 showed a positive pairwise association with illness in these families (P=0.022-0.057). Significant transmission distortion of 4-SNP haplotypes was also observed (P=0.003-0.008). Quantitative trait TDT analyses showed an intriguing association between several SNPs and increased rate of frontal gray matter loss. These observations, when taken together with the positive results reported recently in two independent adult-onset schizophrenia pedigree samples, suggest that the gene encoding GAD67 may be a common risk factor for schizophrenia.