Anthrax Vaccination, Gulf War Illness, and Human Leukocyte Antigen (HLA).

We report on a highly significant, positive association between anthrax vaccination and occurrence of Gulf War Illness (GWI) in 111 Gulf War veterans (42 with GWI and 69 controls). GWI was diagnosed in 47.1% of vaccinated veterans but only in 17.2% of non-vaccinated veterans (Pearson χ2 = 7.08, p = 0.008; odds ratio = 3.947; relative risk = 2.617), with 1.6x higher GWI symptom severity in vaccinated veterans (p = 0.007, F-test in analysis of covariance). Next, we tested the hypothesis that the susceptibility to GWI following anthrax vaccination could be due to inability to make antibodies against the anthrax protective antigen (PA), the key protein contained in the vaccine. Since the first step in initiating antibody production would be the binding of PA peptide fragments (typically 15-amino acid long [15-mer]) to peptide-binding motifs of human leukocyte antigen (HLA) Class II molecules, we assessed the binding-motif affinities of such HLA specific molecules to all linear 15-mer peptide fragments of the anthrax PA. We identified a total of 58 HLA Class II alleles carried by the veterans in our sample and found that, of those, 18 (31%) were present in the vaccinated group that did not develop GWI but were absent from the vaccinated group who developed GWI. Remarkably, in silico analyses revealed very high binding affinities of peptide-binding motifs of those 18 HLA alleles with fragments of anthrax vaccine PA, leading to the successful production of anti-PA antibodies. Conversely, the absence of these protective HLA alleles points to a reduced ability to develop antibodies against PA, thus resulting in harmful PA persistence and development of GWI.

The brain landscape of the two-hit model of posttraumatic stress disorder.

The neurophysiological mechanisms underlying the development of posttraumatic stress disorder (PTSD) are poorly understood. Here we test a proposal that PTSD symptoms reflect fixed, highly correlated neural networks resulting from massive engagement of sensory inputs and the sequential involvement of those projections to limbic areas. Three-tesla functional magnetic resonance imaging (fMRI) data were acquired at rest in 15 veterans diagnosed with PTSD and 21 healthy control veterans from which zero-lag cross correlations between 50 brain areas (N = 1,225 pairs) were computed and analyzed. The brain areas were assigned to tiers based on the neurocircuitry of successively converging sensory pathways proposed by Jones and Powell (Jones EG, Powell TP. Brain 93: 793-820, 1970). The primary analyses assessed normalized proportional differences in cross correlation strength within and across tiers in veterans with PTSD and control veterans. Compared with control veterans, cross correlation strength was higher in veterans with PTSD, within and across tiers of areas involved in processing sensory inputs, and systematically increased from sensory processing areas to limbic areas. The functional relevance of this hypercorrelation was further documented by the finding that the severity of self-reported PTSD symptomatology was positively associated with higher neural correlations.NEW & NOTEWORTHY The neurophysiological mechanisms underlying the development of PTSD are poorly understood. Here we document that massive engagement of sensory modalities during trauma exposure leads to fixed, hypercorrelated frontal, parietal, temporal, and limbic networks, reflecting the successive integration of salient sensory inputs along the framework of Jones and Powell.

Anthrax Protective Antigen 63 (PA63): Toxic Effects in Neural Cultures and Role in Gulf War Illness (GWI).

Protective antigen (PA) 63 (PA63) is a protein derived from the PA83 component contained in the anthrax vaccine. The anthrax vaccine ("Biothrax") was administered together with other vaccines to Gulf War veterans, about 35% of whom later developed a multisymptom disease (Gulf War Illness [GWI]), with prominent neurological/cognitive/mood symptoms, among others. The disease has been traditionally attributed to exposures to toxic chemicals during the war but other factors could be involved, including vaccines received. Of these, the anthrax vaccine is the most toxic. Here, we assessed directly the PA63 toxin's harmful effects on cultured neuroblastoma 2A (N2A) cells with respect to cell spreading, process formation, apoptosis, and integrity of cell membrane, cytoskeleton, and mitochondria. We found that, when added in N2A cultures, PA63 toxin led to decreased cell spreading and cell aggregation, leading to apoptosis. The mechanisms of PA63-induced cell damage included compromised cell membrane permeability indicated by enhanced access of propidium iodide in cells. In addition, signaling pathways leading to organization of N2A cytoskeleton were negatively affected, as both actin and microtubular networks were compromised. Finally, the mitochondrial membrane potential was impaired in specific assays. Altogether, these alterations led to apoptosis as a collective toxic effect of PA63 which was substantially reduced by the concomitant addition of specific antibodies against PA63.

Vaccine-Induced Adverse Effects in Cultured Neuroblastoma 2A (N2A) Cells Duplicate Toxicity of Serum from Patients with Gulf War Illness (GWI) and Are Prevented in the Presence of Specific Anti-Vaccine Antibodies.

Gulf War illness (GWI) is a chronic disease of unknown etiology affecting over 200,000 veterans with symptoms including neurocognitive problems. We previously demonstrated GWI serum toxicity on neural cell cultures manifested by compromised neural network function, decreased cell spreading, and enhanced cell apoptosis. These patients lacked six human leukocyte antigen (HLA) class II alleles, resulting in an inability to form antibodies. Therefore, we hypothesized that GWI patients have vaccine-derived, persistent pathogens, which contribute to the development of the disease. Here, we examined whether individual vaccines were toxic in cultured N2A cells. Moreover, we used antibodies against each of the 20 vaccines administered to Gulf War (GW) veterans, to examine the effects of these antibodies on cell spreading and apoptosis in N2A cells. Antibodies against cholera toxin, hepatitis B, hemagglutinin H1N1, H3N2, and B from influenza A and B strains, measles, and Salmonella Typhi polysaccharide Vi had a remarkable protective effect on both cell spreading and apoptosis, whereas none of the other antibodies administered to GW veterans had an effect. The in vitro observed adverse effects of GWI serum may be due in part to vaccine-derived pathogens, antibodies against which had a protective effect in N2A cell cultures.

The effects of human leukocyte antigen DRB1*13 and apolipoprotein E on age-related variability of synchronous neural interactions in healthy women.

BACKGROUND: Age-related brain changes are well-documented and influenced by genetics. Extensive research links apolipoprotein E (apoE) to brain function, with the E4 allele serving as a risk factor for brain disease, including Alzheimer's disease, and the E2 allele conferring protection. Recent evidence also supports protective effects of another gene, human leukocyte antigen (HLA) DRB1*13, on brain disease and age-related brain atrophy in cognitively healthy adults. Here we investigated the effects of apoE and HLA DRB1*13 on brain function by examining changes in neural network properties with age in healthy adults. METHODS: One hundred seventy-eight cognitively healthy women (28-99 y old) underwent a magnetoencephalography scan and provided a blood sample for genetic analysis. Age-related changes in neural network variability in genetic subgroups of DRB1*13 × apoE genotype combinations were assessed using linear regression of network variability against age. FINDINGS: For individuals lacking a DRB1*13 allele and/or carrying an apoE4 allele, network variability increased significantly with age. In contrast, no such increase was observed in the presence of DRB1*13 and/or apoE2. INTERPRETATION: These findings extend previous research documenting the protective effect of DRB1*13 on brain structure to include protection against age-related changes in brain function, and demonstrate similar protective effects on neural network variability for either DRB1*13 or apoE2. These protective effects could be due to reduction or elimination of factors known to disrupt brain function, including neuroinflammation and amyloid beta protein. FUNDING: U.S. Department of Veterans Affairs, and University of Minnesota.

Protective Effect of Human Leukocyte Antigen (HLA) Allele DRB1*13:02 on Age-Related Brain Gray Matter Volume Reduction in Healthy Women.

BACKGROUND: Reduction of brain volume (brain atrophy) during healthy brain aging is well documented and dependent on genetic, lifestyle and environmental factors. Here we investigated the possible dependence of brain gray matter volume reduction in the absence of the Human Leukocyte Antigen (HLA) allele DRB1*13:02 which prevents brain atrophy in Gulf War Illness (James et al., 2017). METHODS: Seventy-one cognitively healthy women (32-69years old) underwent a structural Magnetic Resonance Imaging (sMRI) scan to measure the volumes of total gray matter, cerebrocortical gray matter, and subcortical gray matter. Participants were assigned to two groups, depending on whether they lacked the DRB1*13:02 allele (No DRB1*13:02 group, N=60) or carried the DRB1*13:02 allele (N=11). We assessed the change of brain gray matter volume with age in each group by performing a linear regression where the brain volume (adjusted for total intracranial volume) was the dependent variable and age was the independent variable. FINDINGS: In the No DRB1*13:02 group, the volumes of total gray matter, cerebrocortical gray matter, and subcortical gray matter were reduced highly significantly. In contrast, none of these volumes showed a statistically significant reduction with age in the DRB1*13:02 group. INTERPRETATION: These findings document the protective effect of DRB1*13:02 on age-dependent reduction of brain gray matter in healthy individuals. Since the role of this allele is to connect to matching epitopes of external antigens for the subsequent production of antibodies and elimination of the offending antigen, we hypothesize that its protective effect may be due to the successful elimination of such antigens to which we are exposed during the lifespan, antigens that otherwise would persist causing gradual brain atrophy. In addition, we consider a possible beneficial role of DRB1*13:02 attributed to its binding to cathepsin S, a known harmful substance in brain aging (Wendt et al., 2008). Of course, other factors covarying with the presence of DRB1*13:02 could be involved.

Brain Function in Gulf War Illness (GWI) and Associated Mental Health Comorbidities.

GWI has affected a substantial number of Gulf War (GW) veterans. The disease involves several organ systems among which the brain is most prominent. Neurological, cognitive and mood-related (NCM) symptoms frequently dominate and are at the root of chronic ill-health and disability in veterans suffering from GWI. In addition, such symptoms frequently co-occur with diagnosable mental health disorders, predominantly posttraumatic stress disorder (PTSD). Here we investigated the possibility that increased GWI severity leads, above a threshold, to a diagnosable mental health disorder (excluding psychosis). For this purpose, we used, in separate analyses, symptom severity scores and resting-state brain functional connectivity patterns, as determined by magnetoencephalography (MEG). Two-hundred-thirty GW-era veterans participated in this study. They completed diagnostic interviews to establish the presence of GWI and assess mental health status. This distinguished 3 groups: healthy controls (N = 41), veterans with GWI and no mental illness (GWI group, N = 91), and veterans with both GWI and mental health disorder (GWI+MH, N = 98). For each veteran, symptom severity scores in the 6 GWI domains (fatigue, pain, NCM, skin, gastrointestinal, respiratory) were available as well as 9 summary measures of the distribution of Synchronous Neural Interactions (SNI) derived from the MEG recordings. We tested the hypothesis that, in the presence of GWI, the appearance of a diagnosable mental health disorder may depend on GWI symptom severity. For that purpose, we performed a logistic regression on the GWI population, where the presence (or absence) of the MH disorder was the dependent variable and the age- and gender-adjusted GWI severity in the 6-symptom domains were the predictors. The outcome was the probability that a participant will have MH disorder or not. Similarly, we tested the hypothesis that the presence of the MH disorder can be predicted by the SNI distribution patterns by performing a second logistic regression as above but with the 9 SNI measures as predictors. We found GWI symptom severity differed significantly across groups (GWI+MH > GWI > Control). SNI distributions of the GWI group also differed significantly from the other groups in a systematic hemispheric pattern, such that the presence of GWI involved predominantly the left hemisphere, and presence of mental health disorders involved, in addition, the right hemisphere. Both logistic regressions yielded highly significant outcomes, demonstrating that both GWI symptom severity and SNI distribution measures can predict the presence of MH disorder in GWI. Remarkably, the prediction probabilities for MH presence derived from the symptom-based and SNI-based logistic regressions were positively and highly statistically significantly correlated. Taken together, both objective (neural) and subjective (symptoms) indices suggest that GWI is distinct from healthy controls and varies in severity in a continuum that leads, at the higher end, to a diagnosable MH disorder. The positive correlation between the GWI symptom-based and brain-based predicted classifications provides a key link between GWI symptom severity and synchronous neural interactions in the context of mental illness.

A Two-Hit Model of The Biological Origin of Posttraumatic Stress Disorder (PTSD).

Posttraumatic stress disorder (PTSD) is a debilitating disorder that can develop following exposure to a traumatic event. Although the cause of PTSD is known, the brain mechanisms of its development remain unknown, especially why it arises in some people but not in others. Most of the research on PTSD has dealt with psychological and brain mechanisms underlying its symptomatology, including intrusive memories, fear and avoidance (see ref.1 for a broad coverage of PTSD research)1. Here we focus, instead, on the origin of PTSD, namely on the neural mechanisms underlying its development. Specifically, we propose a two-hit model for PTSD development, with the following components. (a) The 1st hit is a neuroimmune challenge, as a preexisting condition, and the 2nd hit is intense glutamatergic neurotransmission, induced by the traumatic event; (b) the key molecule that mediates the effects of these two hits is intercellular adhesion molecule 5 (ICAM-5) which was found to be differentially expressed in PTSD2. ICAM-5 is activated by neuroimmune challenge3,4 and glutamatergic neurotransmission5,6, it further enhances glutamatergic transmission6, and exerts a potent effect on synapse formation and neural plasticity, in addition to immunoregulatory functions3,4,7; and (c) with respect to the neural network(s) involved, the brain areas most involved are medial temporal cortical areas, and interconnected cortical and subcortical areas8-10. We hypothesize that the net result of intense glutamatergic transmission in those areas induced by a traumatic event in the presence of ongoing neuroimmune challenge leads to increased levels of ICAM-5 which further enhances glutamatergic transmission and thus leads to a state of a neural network with highly correlated neural interactions, as has been observed in functional neuroimaging studies8-10. We assume that such a "locked-in" network underlies the intrusive re-experiencing in PTSD and maintains associated symptomatology, such as fear and avoidance.

Adverse effects of Gulf War Illness (GWI) serum on neural cultures and their prevention by healthy serum.

Gulf War Illness (GWI) is a chronic debilitating disease of unknown etiology that affects the brain and has afflicted many veterans of the 1990-91 Gulf War (GW). Here we tested the hypothesis that brain damage may be caused by circulating harmful substances to which GW veterans were exposed but which could not be eliminated due to lack of specific immunity. We assessed the effects of serum from GWI patients on function and morphology of brain cultures in vitro, including cultures of embryonic mouse brain and neuroblastoma N2A line. Blood serum from GWI and healthy GW veterans was added, alone and in combination, to the culture and its effects on the function and morphology of the culture assessed. Neural network function was assessed using electrophysiological recordings from multielectrode arrays in mouse brain cultures, whereas morphological assessments (neural growth and cell apoptosis) were done in neuroblastoma cultures. In contrast to healthy serum, the addition of GWI serum disrupted neural network communication and caused reduced cell growth and increased apoptosis. All of these detrimental effects were prevented or ameliorated by the concomitant addition of serum from healthy GW veterans. These findings indicate that GWI serum contains neuropathogenic factors that can be neutralized by healthy serum. We hypothesize that these factors are persistent antigens circulating in GWI blood that can be neutralized, possibly by specific antibodies present in the healthy serum, as proposed earlier1.

Human Immunoglobulin G (IgG) Neutralizes Adverse Effects of Gulf War Illness (GWI) Serum in Neural Cultures: Paving the Way to Immunotherapy for GWI.

Gulf War Illness (GWI) is a chronic debilitating disease of unknown etiology that affects the brain and has afflicted many veterans of the 1990-91 Gulf War (GW). We showed recently1 that blood serum from patients suffering from GWI exerts detrimental effects on neural cultures, including reduced growth, increased apoptosis, and disruption of neural network function. Remarkably, these adverse effects were prevented by the concomitant addition to the culture of serum from healthy Gulf War (GW) era veterans. We interpreted those findings1 in the context of our hypothesis that GWI is, at least partly, due to circulating pathogenic persistent antigens2, probably coming from vaccines administered to GW veterans who lacked crucial Human Leukocyte Antigen (HLA) class 2 alleles3 and, therefore, could not make antibodies against those antigens; by contrast, healthy GW veterans who received the same vaccines and possessed HLA protection3 made antibodies that neutralized the various antigens. Thus, we hypothesized that the beneficial effect of the healthy serum on preventing the adverse GWI serum effects was due to the presence of antibodies against the persistent antigens. Here we tested this hypothesis by assessing the effect of pooled human immunoglobulin G (IgG) on ameliorating the GWI adverse effects on neural growth and apoptosis in neuroblastoma N2A cultures. We tested this effect in 14 GWI patients and found that IgG exerted a potent ameliorating effect by inhibiting the reduction in growth and increased apoptosis of GWI serum. These results lend support to our persistent antigen hypothesis1,2 and suggest an immunotherapy approach for treating GWI. This approach is further strengthened by our finding that the severity of GWI neurocognitive/mood (NCM) symptoms was positively correlated with the degree of apoptosis caused by GWI serum on the neural culture, thus validating the relevance of the apoptotic effect to NCM symptomatology. Finally, we used this relation to predict NCM scores based on the reduced apoptosis effected by IgG addition and found a predicted reduction in NCM symptom severity by ~60%. Altogether, these findings point to the possible beneficial use of IgG in treating GWI.

Human Leukocyte Antigen (HLA) and Gulf War Illness (GWI): HLA-DRB1*13:02 Spares Subcortical Atrophy in Gulf War Veterans.

BACKGROUND: Gulf War Illness (GWI) is a multisystem disorder that has affected a substantial number of veterans who served in the 1990-91 Gulf War. The brain is prominently affected, as manifested by the presence of neurological, cognitive and mood symptoms. We reported previously on the protective role of six Human Leukocyte Antigen (HLA) alleles in GWI (Georgopoulos et al., 2016) and their association with regional brain function (James et al., 2016). More recently, we reported on the presence of subcortical brain atrophy in GWI (Christova et al., 2017) and discussed its possible relation to immune mechanisms. Here we focused on one of the six HLA GWI-protective HLA alleles, DRB1*13:02, which has been found to have a protective role in a broad range of autoimmune diseases (Furukawa et al., 2017), and tested its effects on brain volumes. METHODS: Seventy-six Gulf War veterans (55 with GWI and 21 healthy controls) underwent a structural Magnetic Resonance Imaging (sMRI) scan to measure the volumes of 9 subcortical brain regions to assess differences between participants with (N=11) and without (N=65) HLA class II allele DRB1*13:02. FINDINGS: We found that DRB1*13:02 spared subcortical brain atrophy in Gulf War veterans; overall subcortical volume was 6.6% higher in carriers of DRB1*13:02 (P=0.007). The strongest effect was observed in the volume of cerebellar gray matter which was 9.6% higher (P=0.007) in carriers of DRB1*13:02 than in non-carriers. By contrast, DRB1*13:01 had no effect. INTERPRETATION: These findings document the protective effect of DRB1*13:02 on brain atrophy in Gulf War veterans and are in keeping with recent results documenting sharing of brain mechanisms between GWI and other immune-related diseases (Georgopoulos et al., 2017). We hypothesize that the protective role of DRB1*13:02 is due to its successful elimination of external antigens to which Gulf War veterans were exposed, antigens that otherwise would persist causing low-grade inflammation and possibly leading to autoimmunity. FUNDING SOURCE: U.S. Department of Defense (W81XWH-15-1-0520), Department of Veterans Affairs, American Legion Brain Sciences Chair, and University of Minnesota.

Gulf War illness (GWI) as a neuroimmune disease.

Gulf War illness (GWI) is a chronic disease characterized by the involvement of several organs, including the brain (Christova et al., Exp Brain Res doi: 10.1007/s00221-017-5010-8 , 2017). In a previous study (Georgopoulos et al., J Neural Eng 4:349-355, 2015), we identified six protective alleles from Class II human leukocyte antigen (HLA) genes, and more recently, we investigated the brain correlates of this protection (James et al., EBioMedicine 13:72-79, 2016). Those and other studies (Israeli, Lupus, 21:190-194, 2012) suggested an involvement of the immune system in GWI. In a recent study (Engdahl et al., EBioMedicine doi: 10.1016/j.ebiom.2016.08.030 , 2016), we showed that the brain pattern of synchronous neural interactions (SNI; Georgopoulos et al., J Neural Eng 4:349-355, 2007) in GWI is distinctly different from that in healthy controls. Here we focused on the SNI itself, as a basic measure of neural communication (irrespective of specific connections) and compared it between GWI and seven other diseases that cover a broad spectrum of etiology and pathophysiology. Specifically, we sought to determine which, if any, of those diseases might resemble GWI SNI, overall and within the HLA protective domain, and thus gain further knowledge regarding the nature of GWI brain abnormality. We studied a total of 962 participants from a healthy control population (N = 583) and eight different diseases, including GWI (N = 40), schizophrenia (SZ; N = 21), Alzheimer's disease (AD; N = 66), posttraumatic stress disorder (PTSD; N = 159), major depressive disorder (MDD; N = 10), relapsing-remitting multiple sclerosis (RRMS; N = 43), Sjögren's syndrome (SS; N = 32), and rheumatoid arthritis (RA; N = 8). They all underwent a resting-state magnetoencephalographic (MEG) scan to calculate SNIs. Data were analyzed using analysis of covariance (ANCOVA) with disease as fixed factor, and sex and age as covariates. We found that GWI SNIs differed significantly from control SZ, AD, PTSD and MDD but not from RRMS, SS and RA. In addition, we compared GWI to RRMS, SS and RA with respect to SNIs of MEG sensor pairs that were related to the HLA alleles protective for GWI (James et al., EBioMedicine 13:72-79, 2016). We found that GWI SNIs did not differ significantly from any of these three diseases but they did so from control SZ, AD, PTSD and MDD. These findings indicate that (a) GWI brain synchronicity does not differ significantly from that of known immune-related diseases (RRMS, SS, RA), and (b) that this SNI similarity is present within the HLA-related SNIs. In contrast, GWI SNIs differed significantly from those of the other diseases. We conclude that altered brain communication in GWI likely reflects immune-related processes, as postulated previously (James et al., EBioMedicine 13:72-79, 2016). By extension, these findings also indicate that functional brain abnormalities in RRMS, SS and RA might be, in part, due to lack of protective HLA alleles as documented for GWI (Georgopoulos et al., EBioMedicine 3:79-85, 2015).

Subcortical brain atrophy in Gulf War Illness.

Gulf War Illness (GWI) is a multisystem disorder that has affected a substantial number of veterans who served in the 1990-1991 Gulf War. The brain is prominently affected, as manifested by the presence of neurological, cognitive and mood symptoms. Although brain dysfunction in GWI has been well documented (EBioMedicine 12:127-32, 2016), abnormalities in brain structure have been debated. Here we report a substantial (~10%) subcortical brain atrophy in GWI comprising mainly the brainstem, cerebellum and thalamus, and, to a lesser extent, basal ganglia, amygdala and diencephalon. The highest atrophy was observed in the brainstem, followed by left cerebellum and right thalamus, then by right cerebellum and left thalamus. These findings indicate graded atrophy of regions anatomically connected through the brainstem via the crossed superior cerebellar peduncle (left cerebellum â†’ right thalamus, right cerebellum â†’ left thalamus). This distribution of atrophy, together with the observed systematic reduction in volume of other subcortical areas (basal ganglia, amygdala and diencephalon), resemble the distribution of atrophy seen in toxic encephalopathy (Am J Neuroradiol 13:747-760, 1992) caused by a variety of substances, including organic solvents. Given the potential exposure of Gulf War veterans to "a wide range of biological and chemical agents including sand, smoke from oil-well fires, paints, solvents, insecticides, petroleum fuels and their combustion products, organophosphate nerve agents, pyridostigmine bromide, …" (Institute of Medicine National Research Council. Gulf War and Health: Volume 1. Depleted uranium, pyridostigmine bromide, sarin, and vaccines. National Academies Press, Washington DC, 2000), it is reasonable to suppose that such exposures, alone or in combination, could underlie the subcortical atrophy observed.

Apolipoprotein E: the resilience gene.

The apolipoprotein E (apoE) gene has been implicated in various conditions, most notably Alzheimer's disease and coronary artery disease. A predisposing role of the apoE4 isoform and a protective role of apoE2 isoform in those diseases have been documented. Here we investigated the role of apoE in resilience to trauma. Three hundred and forty-three US veterans were genotyped for apoE and were assessed for their lifetime trauma exposure (trauma score, T) and severity of posttraumatic stress disorder symptoms (PCL). The ratio PCL/T indicates sensitivity to trauma; hence, its inverse indicates resilience, R, to trauma. We found a significantly higher resilience in participants with apoE genotype containing the E2 allele (E2/2, E2/3) as compared to participants with the E4 allele (E4/4, E4/3). In addition, when the categorical apoE genotype was reexpressed as the number of cysteine residues per apoE mole (CysR/mole), a highly significant positive association was found between resilience and CysR/mole, such that resilience was systematically higher as the number of CysR/mole increased, from zero CysR/mole in E4/4 to four CysR/mole in E2/2. These findings demonstrate the protective role of the CysR/mole apoE in resilience to trauma: the more CysR/mole, the higher the resilience. Thus, they are in accord with other findings pointing to a generally protective role of increasing number of CysR/mole (from E4/4 to E2/2) in other diseases. However, unlike other conditions (e.g., Alzheimer's disease and coronary artery disease), resilience to trauma is not a disease but an adaptive response to trauma. Therefore, the effects of apoE seem to be more pervasive along the CysR/mole continuum, most probably reflecting underlying effects on brain synchronicity and its variability that we have documented previously (Leuthold et al., Exp Brain Res 226:525-536, 2013).

Brain Correlates of Human Leukocyte Antigen (HLA) Protection in Gulf War Illness (GWI).

BACKGROUND: We recently reported that six alleles from class II genes of the Human Leukocyte Antigen (HLA) confer protection from Gulf War Illness (GWI) (Georgopoulos et al., 2015). The most significant effect is exerted on Neurological-Cognitive-Mood (NCM), Pain, and Fatigue symptoms, such that higher number of copies of the protective alleles are associated with lower symptom severity. Here we tested the hypothesis that this effect is exerted by modulating the strength of neural synchronicity. METHODS: Eighty-one Gulf War veterans (65 with GWI and 16 healthy controls) underwent a magnetoencephalography (MEG) scan to assess the strength of brain synchronicity by computing zero-lag crosscorrelations (and their Fisher z transforms) between prewhitened MEG time series. A high-resolution HLA genotyping determined the number of copies, k, of the 6 protective alleles above in each participant. We tested the hypothesis above by regressing NCM, Pain and Fatigue symptom severity against the interaction term, k×z (HLA-related effect), while including z (non-HLA-related effect), gender and age as covariates. The k×z and z terms assessed HLA- and non-HLA-related effects, respectively, of neural synchronicity on symptom severity. The distributions of these effects in sensor space were visualized using statistical heatmaps. FINDINGS: We found significant, graded HLA- and non-HLA-related effects: (a) NCM>Pain>Fatigue for HLA-related effects, (b) NCM>Fatigue>Pain for non-HLA-related effects, and (c) HLA-related>non-HLA-related effects for all symptoms. These effects had widespread but distinct distributions in sensor space that allowed the orderly separation of the 6 terms (3 symptom domains×2 HLA factors) in a multidimensional plot, where one dimension separated the symptoms and the other the HLA relation. INTERPRETATION: These findings demonstrate the presence of substantial, widespread, distinct and orderly HLA- and non-HLA-related neural influences on NCM, Pain and Fatigue symptom severity in GWI. FUNDING: U.S. Department of Veterans Affairs and University of Minnesota.

A Magnetoencephalographic (MEG) Study of Gulf War Illness (GWI).

BACKGROUND: Gulf War Illness (GWI) has affected many Gulf War veterans. It involves several organs, most notably the brain. Neurological-cognitive-mood-related symptoms frequently dominate and are at the root of chronic ill-health and disability in GWI. Here we investigated the neural mechanisms underlying brain dysfunction in GWI in the absence of mental health disorders. METHODS: Eighty-six veterans completed diagnostic interviews to establish the presence of GWI and assess mental health status. Participants diagnosed with GWI met both Center for Disease Control and Kansas criteria. We studied 46 healthy controls and 40 veterans with GWI without mental illness. They all underwent a resting-state magnetoencephalographic (MEG) scan to assess brain communication based on synchronous neural interactions (SNI; Georgopoulos et al., 2007). FINDINGS: We found substantial differences in SNI between control and GWI groups centered on the cerebellum and frontal cortex. In addition, using the maxima and minima of SNI per sensor as predictors, we successfully classified 94.2% of the 86 participants (95% sensitivity, 93.5% specificity). INTERPRETATION: These findings document distinct differences in brain function between control and GWI in the absence of mental health comorbidities, differences that are excellent predictors of GWI. FUNDING: U.S. Department of Veterans Affairs and University of Minnesota.

Reduced Human Leukocyte Antigen (HLA) Protection in Gulf War Illness (GWI).

BACKGROUND: Gulf War Illness (GWI) is a disease of unknown etiology with symptoms suggesting the involvement of an immune process. Here we tested the hypothesis that Human Leukocyte Antigen (HLA) composition might differ between veterans with and without GWI. METHODS: We identified 144 unique alleles of Class I and II HLA genes in 82 veterans (66 with and 16 without GWI). We tested the hypothesis that a subset of HLA alleles may classify veterans in their respective group using a stepwise linear discriminant analysis. In addition, each participant rated symptom severity in 6 domains according to established GWI criteria, and an overall symptom severity was calculated. FINDINGS: We found 6 Class II alleles that classified participants 84.1% correctly (13/16 control and 56/66 GWI). The number of copies of the 6 alleles was significantly higher in the control group, suggesting a protective role. This was supported by a significant negative dependence of overall symptom severity on the number of allele copies, such that symptom severity was lower in participants with larger numbers of allele copies. INTERPRETATION: These results indicate a reduced HLA protection (i.e. genetic susceptibility) in veterans with GWI. FUNDING: University of Minnesota and U.S. Department of Veterans Affairs.

Pathological personality traits modulate neural interactions.

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), includes an empirically supported dimensional model of personality pathology that is assessed via the Personality Inventory for the DSM-5 (PID-5). Here we used magnetoencephalography (MEG; 248 sensors) to evaluate resting-state neural network properties associated with the five primary DSM-5 maladaptive personality domains (negative affect, detachment, antagonism, disinhibition, and psychoticism) in 150 healthy veterans ("control" group) and 179 veterans with various psychiatric disorders ("psychopathology" group). Since a fundamental network property is the strength of functional connectivity among network elements, we used the absolute value of the pairwise correlation coefficient (aCC) between prewhitened MEG sensor time series as a measure of neural functional connectivity and assessed its relations to the quantitative PID-5 scores in a linear regression model, where the log-transformed aCC was the dependent variable and individual PID scores, age, and gender were the independent variables. The partial regression coefficient (pRC) for a specific PID-5 score in that model provided information concerning the direction (positive, negative) and size (absolute value) of the PID effect on the strength of neural correlations. We found that, overall, PID domains had a negative effect (i.e., negative pRC; decorrelation) on aCC in the control group, but a positive one (i.e., positive pRC; hyper-correlation) in the psychopathology group. This dissociation of PID effects on aCC was especially pronounced for disinhibition, psychoticism, and negative affect. These results document for the first time a fundamental difference in neural-PID relations between control and psychopathology groups.

Diagnosis of posttraumatic stress disorder (PTSD) based on correlations of prewhitened fMRI data: outcomes and areas involved.

Successful diagnosis of PTSD has been achieved using neural correlations from prewhitened magnetoencephalographic (MEG) time series (Georgopoulos et al. in J Neural Eng 7:16011, 2010. doi:10.1088/1741-2560/7/1/016011; James et al. 2015). Here, we show that highly successful classification of PTSD and control subjects can be obtained using neural correlations from prewhitened resting-state fMRI data. All but one PTSD (14/15; sensitivity = 93.3 %) and all but one control (20/21; specificity = 95.2 %) subjects were correctly classified using 15 out of 2701 possible correlations between 74 brain areas. In contrast, correlations of the same but non-prewhitened data yielded chance-level classifications. We conclude that, if properly processed, fMRI has the prospect of aiding significantly in PTSD diagnosis. Twenty-five brain areas were most prominently involved in correct subject classification, including areas from all cortical lobes and the left pallidum.

DSM-5 personality traits discriminate between posttraumatic stress disorder and control groups.

The relevance of personality traits to the study of psychopathology has long been recognized, particularly in terms of understanding patterns of comorbidity. In fact, a multidimensional personality trait model reflecting five higher-order personality dimensions-negative affect, detachment, antagonism, disinhibition, and psychoticism-is included in the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) and represented in the Personality Inventory for DSM-5 (PID-5). However, evaluation of these dimensions and underlying personality facets within clinical samples has been limited. In the present study, we utilized the PID-5 to evaluate the personality profile elevation and composition of 150 control veterans and 35 veterans diagnosed with posttraumatic stress disorder (PTSD). Results indicated that veterans with PTSD endorsed significantly more personality pathology than control veterans, with scores on detachment and psychoticism domains most clearly discriminating between the two groups. When personality domain scores were considered as parts of each subject's personality profile, a slightly different picture emerged. Specifically, the PTSD composition was primarily characterized by detachment and negative affect, followed by disinhibition, psychoticism, and antagonism in that order of relative importance. The profile of the control group was significantly different, mostly accounted for differences in antagonism and psychoticism. Using these complementary analytic strategies, the findings demonstrate the relevance of personality pathology to PTSD, highlight internalizing features of PTSD, and pave the way for future research aimed at evaluating the role of shared maladaptive personality traits in underlying the comorbidity of PTSD and related disorders.