Stimulation of Pro-inflammatory Cytokines in Mixed Cultures of Peripheral Blood Mononuclear Cells and Anaerobic Bacteria.

In the last couple of decades, much progress has been made in studying bacteria living in humans. However, there is much more to learn about bacteria immune cell interactions. Here, we show that anaerobic bacteria do not grow when cultured overnight with human cells under atmospheric air. Air contains about 18% oxygen, which inhibits the growth of these bacteria while supporting the cultivation of human cells. The bacteria cultured with human peripheral blood mononuclear cells (PBMCs) inflamed with phytohemagglutinin (PHA) greatly increased the production of proinflammatory cytokines like tumor necrosis factor-alpha (TNFα) while inhibiting the production of monocyte chemoattractant protein-1 (MCP-1), an important chemokine.

Brief Report: Low Rates of Herpesvirus Detection in Blood of Individuals with Autism Spectrum Disorder and Controls.

Previous research indicates that infection, especially from viruses in the family Herpesviridae, may play a role in the etiology of some cases of autism spectrum disorder (ASD). Using a case-control design and the polymerase chain reaction with site-specific primers, we screened newborn and childhood blood samples for the presence of eight human herpesviruses. Herpesvirus DNA was detected in 4 of 225 ASD individuals and 2 of 235 controls, with the most frequently detected virus being HHV-6B. Although this study does not detect a significant ASD-Herpesviridae association, it is limited by the use of site-specific primers. We suggest that new techniques using bioinformatics to search next-generation sequencing databases will be more revealing of possible ASD-virus associations.

Direct analysis - no sample preparation - of bioavailable cortisol in human plasma by weak affinity chromatography (WAC).

Pre-analytical treatment of blood plasma is a time consuming and often rate limiting step in the workflow of LC/MS analysis. We present in this pilot study a new approach for quantitative LC/MS based on weak affinity chromatography (WAC) of crude plasma. The steroid hormone cortisol was selected as a clinically relevant biomarker, as it currently requires extensive pre-analytical preparation. A WAC unit with saturating, immobilized albumin as a prototypic weak binder was used in combination with an ion-funnel MS/MS detector to perform zonal affinity chromatography of cortisol directly from a plasma sample, followed by quantitative multiple reaction monitoring (MRM). This procedure also allowed us to determine the amount of bioavailable cortisol in the clinical plasma sample which is of significant therapeutic interest. This WAC-MS approach showed an excellent correlation (R2=0.86 (P<0.0001 (highly significant); n=60) with a state-of-the-art, clinical competitive immunoassay procedure for plasma cortisol analysis. With integration of WAC into LC/MS workflow, it may be possible to both accelerate and improve assay performance by eliminating the sample extraction step. Preliminary data with other steroid hormones indicate that WAC-MS can be applied to various biomolecules using a plasma transport protein such as albumin.

Independent Maternal and Fetal Genetic Effects on Midgestational Circulating Levels of Environmental Pollutants.

Maternal exposure to environmental pollutants could affect fetal brain development and increase autism spectrum disorder (ASD) risk in conjunction with differential genetic susceptibility. Organohalogen congeners measured in maternal midpregnancy blood samples have recently shown significant, but negative associations with offspring ASD outcome. We report the first large-scale maternal and fetal genetic study of the midpregnancy serum levels of a set of 21 organohalogens in a subset of 790 genotyped women and 764 children collected in California by the Early Markers for Autism (EMA) Project. Levels of PCB (polychlorinated biphenyl) and PBDE (polybrominated diphenyl ether) congeners showed high maternal and fetal estimated SNP-based heritability (h2g ) accounting for 39-99% of the total variance. Genome-wide association analyses identified significant maternal loci for p,p'-DDE (P = 7.8 × 10-11) in the CYP2B6 gene and for BDE-28 (P = 3.2 × 10-8) near the SH3GL2 gene, both involved in xenobiotic and lipid metabolism. Fetal genetic loci contributed to the levels of BDE-100 (P = 4.6 × 10-8) and PCB187 (P = 2.8 × 10-8), near the potential metabolic genes LOXHD1 and PTPRD, previously implicated in neurodevelopment. Negative associations were observed for BDE-100, BDE153, and the sum of PBDEs with ASD, partly explained by genome-wide additive genetic effects that predicted PBDE levels. Our results support genetic control of midgestational biomarkers for environmental exposures by nonoverlapping maternal and fetal genetic determinants, suggesting that future studies of environmental risk factors should take genetic variation into consideration. The independent influence of fetal genetics supports previous hypotheses that fetal genotypes expressed in placenta can influence maternal physiology and the transplacental transfer of organohalogens.

Common Genetic Variants Found in HLA and KIR Immune Genes in Autism Spectrum Disorder.

The "common variant-common disease" hypothesis was proposed to explain diseases with strong inheritance. This model suggests that a genetic disease is the result of the combination of several common genetic variants. Common genetic variants are described as a 5% frequency differential between diseased vs. matched control populations. This theory was recently supported by an epidemiology paper stating that about 50% of genetic risk for autism resides in common variants. However, rare variants, rather than common variants, have been found in numerous genome wide genetic studies and many have concluded that the "common variant-common disease" hypothesis is incorrect. One interpretation is that rare variants are major contributors to genetic diseases and autism involves the interaction of many rare variants, especially in the brain. It is obvious there is much yet to be learned about autism genetics. Evidence has been mounting over the years indicating immune involvement in autism, particularly the HLA genes on chromosome 6 and KIR genes on chromosome 19. These two large multigene complexes have important immune functions and have been shown to interact to eliminate unwanted virally infected and malignant cells. HLA proteins have important functions in antigen presentation in adaptive immunity and specific epitopes on HLA class I proteins act as cognate ligands for KIR receptors in innate immunity. Data suggests that HLA alleles and KIR activating genes/haplotypes are common variants in different autism populations. For example, class I allele (HLA-A2 and HLA-G 14 bp-indel) frequencies are significantly increased by more than 5% over control populations (Table 2). The HLA-DR4 Class II and shared epitope frequencies are significantly above the control populations (Table 2). Three activating KIR genes: 3DS1, 2DS1, and 2DS2 have increased frequencies of 15, 22, and 14% in autism populations, respectively. There is a 6% increase in total activating KIR genes in autism over control subjects. And, more importantly there is a 12% increase in activating KIR genes and their cognate HLA alleles over control populations (Torres et al., 2012a). These data suggest the interaction of HLA ligand/KIR receptor pairs encoded on two different chromosomes is more significant as a ligand/receptor complex than separately in autism.

Prenatal and Newborn Immunoglobulin Levels from Mother-Child Pairs and Risk of Autism Spectrum Disorders.

BACKGROUND: An etiological role for immune factors operating during early brain development in children with autism spectrum disorders (ASD) has not yet been established. A major obstacle has been the lack of early biologic specimens that can be linked to later diagnosis. In a prior study, we found lower risk of ASD associated with higher levels of maternally-derived total IgG and Toxoplasmosis gondii (Toxo) IgG in newborn blood spot specimens from children later diagnosed with ASD compared to population controls. METHODS: We obtained maternal mid-gestational serum specimens and newborn screening blood spots from the California Genetics Disease Screening Program (GDSP) for linked mother-baby pairs for 84 children with ASD and 49 children with developmental delay but not ASD (DD) identified from California Department of Developmental Services records and for 159 population controls sampled from birth certificates.Immunoglobulin levels in maternal and newborn specimens were measured by solid phase immunoassays and analyzed in logistic regression models for total IgG, total IgM, and Toxo IgG, and, for maternal specimens only, Toxo IgM. Correlations between maternal and newborn ranked values were evaluated. RESULTS: In both maternal and newborn specimens, we found significantly lower risk of ASD associated with higher levels of Toxo IgG. In addition, point estimates for all comparisons were < 1.0 suggesting an overall pattern of lower immunoglobulin levels associated with higher ASD risk but most did not reach statistical significance. We did not find differences in maternal or newborn specimens comparing children with DD to controls. DISCUSSION: These results are consistent with evidence from our prior study and other published reports indicating that immune factors during early neurodevelopment may be etiologically relevant to ASD. Lowered immunoglobulin levels may represent suboptimal function of the maternal immune system or reduced maternal exposure to common infectious agents. CONCLUSION: Patterns seen in these selected immunoglobulins may provide clues to mechanisms of early abnormalities in neurodevelopment contributing to ASD. We recommend further study of immunoglobulin profiles in larger samples of linked mother-baby pairs to evaluate possible etiologic relevance.

A genome-wide survey of transgenerational genetic effects in autism.

Effects of parental genotype or parent-offspring genetic interaction are well established in model organisms for a variety of traits. However, these transgenerational genetic models are rarely studied in humans. We have utilized an autism case-control study with 735 mother-child pairs to perform genome-wide screening for maternal genetic effects and maternal-offspring genetic interaction. We used simple models of single locus parent-child interaction and identified suggestive results (P<10(-4)) that cannot be explained by main effects, but no genome-wide significant signals. Some of these maternal and maternal-child associations were in or adjacent to autism candidate genes including: PCDH9, FOXP1, GABRB3, NRXN1, RELN, MACROD2, FHIT, RORA, CNTN4, CNTNAP2, FAM135B, LAMA1, NFIA, NLGN4X, RAPGEF4, and SDK1. We attempted validation of potential autism association under maternal-specific models using maternal-paternal comparison in family-based GWAS datasets. Our results suggest that further study of parental genetic effects and parent-child interaction in autism is warranted.

Genetic risk factors for perinatal arterial ischemic stroke.

The cause of perinatal arterial ischemic stroke is unknown in most cases. We explored whether genetic polymorphisms modify the risk of perinatal arterial ischemic stroke. In a population-based case-control study of 1997-2002 births at Kaiser Permanente Northern California, we identified 13 white infants with perinatal arterial ischemic stroke. Control subjects included 86 randomly selected white infants. We genotyped polymorphisms in nine genes involved in inflammation, thrombosis, or lipid metabolism previously linked with stroke, and compared genotype frequencies in case and control individuals. We tested several polymorphisms: tumor necrosis factor-α -308, interleukin-6, lymphotoxin A, factor V Leiden, methyltetrahydrofolate reductase 1298 and 667, prothrombin 20210, and apolipoprotein E ε2 and ε4 alleles. Patients with perinatal arterial ischemic stroke were more likely than control subjects to demonstrate at least one apolipoprotein E ε4 allele (54% vs 25%, P = 0.03). More patients with perinatal arterial ischemic stroke carried two ε4 alleles than did control subjects (15% vs 2%, P = 0.09), although this finding lacked statistical significance. Proinflammatory and prothrombotic polymorphisms were not associated with perinatal arterial ischemic stroke. The apolipoprotein E polymorphism may confer genetic susceptibility for perinatal arterial ischemic stroke. Larger population-based studies are required to confirm this finding.

Activating killer-cell immunoglobulin-like receptors (KIR) and their cognate HLA ligands are significantly increased in autism.

Killer-cell immunoglobulin-like receptor (KIR) proteins are expressed on natural killer (NK) cells and appear important in innate and adaptive immunity. There are about 14 KIR genes on chromosome 19q13.4, composed of those that inhibit and those that activate NK cell killing. Haplotypes have different combinations of these genes meaning that not all genes are present in a subject. There are two main classes of cognate human leukocyte antigen (HLA) ligands (HLA-Bw4 and HLA-C1/C2) that bind to the inhibitory/activating receptors. As a general rule, the inhibitory state is maintained except when virally infected or tumor cells are encountered; however, both increased activation and inhibition states have been associated with susceptibility and protection against numerous disease states including cancer, arthritis, and psoriasis. Utilizing DNA from 158 Caucasian subjects with autism and 176 KIR control subjects we show for the first time a highly significant increase in four activating KIR genes (2DS5, 3DS1, 2DS1 and 2DS4) as measured by chi square values and odds ratios. In addition, our data suggests a highly significant increase in the activating KIR gene 2DS1 and its cognate HLA-C2 ligand (2DS1+C2; p = 0.00003 [Odds ratio = 2.87]). This information ties together two major immune gene complexes, the human leukocyte complex and the leukocyte receptor complex, and may partially explain immune abnormalities observed in many subjects with autism.

HLA Immune Function Genes in Autism.

The human leukocyte antigen (HLA) genes on chromosome 6 are instrumental in many innate and adaptive immune responses. The HLA genes/haplotypes can also be involved in immune dysfunction and autoimmune diseases. It is now becoming apparent that many of the non-antigen-presenting HLA genes make significant contributions to autoimmune diseases. Interestingly, it has been reported that autism subjects often have associations with HLA genes/haplotypes, suggesting an underlying dysregulation of the immune system mediated by HLA genes. Genetic studies have only succeeded in identifying autism-causing genes in a small number of subjects suggesting that the genome has not been adequately interrogated. Close examination of the HLA region in autism has been relatively ignored, largely due to extraordinary genetic complexity. It is our proposition that genetic polymorphisms in the HLA region, especially in the non-antigen-presenting regions, may be important in the etiology of autism in certain subjects.

California Very Preterm Birth Study: design and characteristics of the population- and biospecimen bank-based nested case-control study.

Very preterm birth (VPTB) is a leading cause of infant mortality, morbidity and racial disparity in the US. The underlying causes of VPTB are multiple and poorly understood. The California Very Preterm Birth Study was conducted to discover maternal and infant genetic and environmental factors associated with VPTB. This paper describes the study design, population, data and specimen collection, laboratory methods and characteristics of the study population. Using a large, population-based cohort created through record linkage of livebirths delivered from 2000 to 2007 in five counties of southern California, and existing data and banked specimens from statewide prenatal and newborn screening, 1100 VPTB cases and 796 control mother-infant pairs were selected for study (385/200 White, 385/253 Hispanic and 330/343 Black cases/controls, respectively). Medical record abstraction of cases was conducted at over 50 hospitals to identify spontaneous VPTB, improve accuracy of gestational age, obtain relevant clinical data and exclude cases that did not meet eligibility criteria. VPTB was defined as birth at <32 weeks in Whites and Hispanics and <34 weeks in Blacks. Approximately 55% of all VPTBs were spontaneous and 45% had medical indications or other exclusions. Of the spontaneous VPTBs, approximately 41% were reported to have chorioamnionitis. While the current focus of the California Very Preterm Birth Study is to assess the role of candidate genetic markers on spontaneous VPTB, its design enables the pursuit of other research opportunities to identify social, clinical and biological determinants of different types of VPTB with the ultimate aim of reducing infant mortality, morbidity and racial disparities in these health outcomes in the US and elsewhere.

Candidate genes and risk for CP: a population-based study.

Studies suggest that genetic polymorphisms may increase an individual's susceptibility to CP. Most findings have yet to be corroborated in an independent cohort. This case-control study is nested within all 334,333 infants ≥36 wk gestation born at Kaiser Permanente Medical Care Program, 1991-2002. We included only non-Hispanic whites who had a neonatal blood sample available. Case patients (n = 138) were identified from medical records to have spastic or dyskinetic CP. Controls (n = 165) were randomly selected from the population. We genotyped polymorphisms previously associated with CP: inducible NOS (iNOS)-231, apolipoprotein E (apoE) ε2 and ε4 alleles, TNF-α-308, IL-8 -251, lymphotoxin 60, endothelial NOS -922, endothelial protein C receptor 219, mannose-binding lectin 54 and 52, factor V Leiden, methyltetrahydrofolate reductase 1298 and 667, prothrombin 20210, and platelet activator inhibitor 11053. Similar to previous reports, the iNOS-231 T allele (25.7 versus 18.9%, p = 0.04) and the apoE ε4 allele (19.3 versus 13.2%, p = 0.04) were more common in patients with CP than in controls. However, there was no statistically significant association between any genetic polymorphism and CP after correction for multiple comparisons.

Autism spectrum disorders are associated with an elevated autoantibody response to tissue transglutaminase-2.

We report that a significant number of autistic children have serum levels of IgA antibodies above normal to the enzyme tissue transglutaminase II (TG2), and that expression of these antibodies to TG2 is linked to the (HLA)-DR3, DQ2 and DR7, DQ2 haplotypes. TG2 is expressed in the brain, where it has been shown to be important in cell adhesion and synaptic stabilization. Thus, these children appear to constitute a subpopulation of autistic children who fall within the autism disease spectrum, and for whom autoimmunity may represent a significant etiological component of their autism.

Interleukin-6 genotype and risk for cerebral palsy in term and near-term infants.

OBJECTIVE: Chorioamnionitis is associated with increased risk for cerebral palsy (CP) in term infants. A functional polymorphism in the interleukin-6 (IL-6) gene has been implicated in newborn brain injury. We studied whether the IL-6 -174 G/C polymorphism confers increased risk for CP in term infants. METHODS: This population-based case-control study included 334,333 live-born infants born at >or=36 weeks gestation within Kaiser Permanente Medical Care Program from 1991 to 2002. Case patients (n = 250) were identified from electronic records and confirmed by chart review, and comprised all infants with spastic or dyskinetic CP not caused by developmental abnormalities who had a neonatal blood specimen available for study. Control patients (n = 305) were randomly selected from the study population. RESULTS: Compared with genotype GG, the less common CC genotype was associated with increased risk for overall CP (odds ratio [OR], 2.6; 95% confidence interval [CI], 1.5-4.6), quadriparetic CP (OR, 4.1; 95% CI, 1.8-9.3), and hemiparetic CP (OR, 2.7; 95% CI, 1.3-5.7), after controlling for race. The C allele conferred increased risk for CP in both recessive and additive genetic models. In multivariate analysis controlling for race, independent risk factors for CP included CC genotype compared with GG (OR, 2.4; 95% CI, 1.3-4.4), clinical chorioamnionitis (OR, 4.6; 95% CI, 2.1-10.4), maternal age >or= 35 (OR, 2.6; 95% CI, 1.6-4.1), and male sex (OR, 1.6; 95% CI, 1.1-2.4). INTERPRETATION: Our data suggest that a functional polymorphism in the IL-6 gene is a risk factor for CP among term and near-term infants.

C4B null alleles are not associated with genetic polymorphisms in the adjacent gene CYP21A2 in autism.

BACKGROUND: Research indicates that the etiology of autism has a strong genetic component, yet so far the search for genes that contribute to the disorder, including several whole genome scans, has led to few consistent findings. However, three studies indicate that the complement C4B gene null allele (i.e. the missing or nonfunctional C4B gene) is significantly more frequent in individuals with autism. Due to the close proximity of the CYP21A2 gene to the C4B locus (3 kb) it was decided to examine samples from autistic subjects, including many with known C4B null alleles for common CYP21A2 mutations. METHODS: Samples from subjects diagnosed with autism and non-autistic controls (controls) previously typed for C4B null alleles were studied. Allele specific polymerase chain reaction (PCR) methods were used to determine 8 of the most common CYP21A2 genetic mutations, known to completely or partially inhibit 21-hydroxylase, the enzyme encoded by the CYP21A2 gene. RESULTS: Although the combined autism and control study subjects had 50 C4B null alleles only 15 CYP21A2 mutations were detected in over 2250 genotypes. Eight mutations were detected in the autistic samples and 7 in the controls. The frequency of CYP21A2 mutations was similar between the autism and control samples. Only one individual (autistic) carried a chromosome containing both C4B null allele and CYP21A2 mutations.

Effects of cidofovir treatment on cytokine induction in murine models of cowpox and vaccinia virus infection.

Cytokine profiles during cowpox and vaccinia (WR strain) virus infections were characterized in intranasal (i.n.) and intraperitoneal (i.p.) models in BALB/c mice. The time-course of induction and effects of cidofovir treatment on interferon (IFN)-gamma, IFN-gamma inducible protein (IP)-10, interleukin (IL)-6, and monocyte chemoattractant protein (MCP)-1 were determined. The four mouse infection models have distinct patterns of cytokine induction. Cowpox virus i.p. and vaccinia virus i.n. infections showed increased induction throughout the time studied. Cowpox virus i.n. infection resulted in delayed induction of IFN-gamma and IP-10. Cytokine levels were fairly constant during vaccinia virus i.p. infections. Cidofovir treatment (100mg/kg/day i.p. for 2 days) significantly suppressed certain cytokine (IFN- gamma, IL-6, IL-10, IL-11, IP-10, LIF, MCP-1, MCP-3, MCP-5, MIP-1 gamma, and TIMP-1) levels to near normal relative to uninfected animals, as well as prevented mortality and reduced virus titers significantly. Characterization of cytokine responses has implications for understanding the immune responses and pathogeneses of viral infections in these mouse models.

The association and linkage of the HLA-A2 class I allele with autism.

Previous research has revealed associations between autism and immune genes located in the human leukocyte antigen (HLA). To better understand which HLA genetic loci may be associated with autism, we compared the class I HLA-A and -B alleles in autistic probands with case control subjects from Caucasian families. The frequency of HLA-A2 alleles was significantly increased in autistic subjects compared with normal allelic frequencies from the National Marrow Donors Program (NMDP) (p = 0.0043 after allelic correction). The transmission disequilibrium test for the A2 allele revealed an increased frequency of inheritance for autistic children (p = 0.033). There were no significant associations of autism with HLA-B alleles; however, the A2-B44 and A2-B51 haplotypes were two times more frequent in autistic subjects. The association and linkage of the class I HLA-A2 allele with autism suggests its involvement in the etiology of autism. Possible roles are discussed for the HLA-A2 association in the presentation of microbial antigen within the central nervous system and/or in the establishment of synaptic and neuronal circuits in the developing brain.

Is fever suppression involved in the etiology of autism and neurodevelopmental disorders?

BACKGROUND: There appears to be a significant increase in the prevalence rate of autism. Reasons for the increase are unknown, however, there is a substantial body of evidence that suggests the etiology involves infections of the pregnant mother or of a young child. Most infections result in fever that is routinely controlled with antipyretics such as acetaminophen. The blocking of fever inhibits processes that evolved over millions of years to protect against microbial attack. Immune mechanisms in the central nervous system are part of this protective process. HYPOTHESIS: The blockage of fever with antipyretics interferes with normal immunological development in the brain leading to neurodevelopmental disorders such as autism in certain genetically and immunologically disposed individuals. TESTING THE HYPOTHESIS: Epidemiological studies to determine associations between the use of antipyretics and neurodevelopmental disorders should be undertaken. Biochemical tests will involve the examination of fluids/serum by mass spectrometry and the determination of cytokine/chemokine levels in serum and cell culture fluids after stimulation with fever-inducing molecules from bacteria, viruses and yeast. Postmortem brain can be examined by immunohistochemistry or other methods such as fluorescent in situ hybridization (FISH) to determine altered expression levels of chemokines/cytokines and other molecules. IMPLICATIONS OF THE HYPOTHESIS: 1) The use of antipyretics during pregnancy or in young children may be reserved for more severe fevers. 2) The perplexing genetic findings in autism may be better understood by categorizing genes along functional pathways. 3) New treatments based on immune, cell, pharmacological or even heat therapies may be developed.

The transmission disequilibrium test suggests that HLA-DR4 and DR13 are linked to autism spectrum disorder.

We have evaluated possible contributions of HLA-DRB1 alleles to autism spectrum disorder (ASD) in 103 families of Caucasian descent. The DR4 allele occurred more often in probands than controls (0.007), whereas the DR13,14 alleles occurred less often in probands than controls (p = 0.003). The transmission disequilibrium test (TDT) indicated that the ASD probands inherited the DR4 allele more frequently than expected (p = 0.026) from the fathers. The TDT also revealed that fewer DR13 alleles than expected were inherited from the mother by ASD probands (p = 0.006). We conclude that the TDT results suggest that DR4 and DR13 are linked to ASD. Reasons for the parental inheritance of specific alleles are poorly understood but coincide with current genetic research noting possible parent-of-origin effects in autism.