Negative association between neurovascular coupling and cortical gray matter volume during the lifespan

Recent studies have established the moment-to-moment turnover of the blood-oxygen-level-dependent signal (TBOLD) at resting state as a key measure of local cortical brain function. Here, we sought to extend that line of research by evaluating TBOLD in 70 cortical areas with respect to corresponding brain volume, age, and sex across the lifespan in 1,344 healthy participants including 633 from the Human Connectome Project (HCP)-Development cohort (294 males and 339 females, age range 8-21 yr) and 711 healthy participants from HCP-Aging cohort (316 males and 395 females, 36-90 yr old). In both groups, we found that 1) TBOLD increased with age, 2) volume decreased with age, and 3) TBOLD and volume were highly significantly negatively correlated, independent of age. The inverse association between TBOLD and volume was documented in nearly all 70 brain areas and for both sexes, with slightly stronger associations documented for males. The strong correspondence between TBOLD and volume across age and sex suggests a common influence such as chronic neuroinflammation contributing to reduced cortical volume and increased TBOLD across the lifespan.NEW & NOTEWORTHY We report a significant negative association between resting functional magnetic resonance imaging (fMRI) blood-oxygen-level-dependent (BOLD) signal turnover (TBOLD) and cortical gray matter volume across the lifespan, such that TBOLD increased whereas volume decreased. We attribute this association to a hypothesized chronic, low-grade neuroinflammation, probably induced by various neurotropic pathogens, including human herpes viruses known to be dormant in the brain in a latent state and reactivated by stress, fever, and various environmental exposures, such as ultraviolet light.

Anthrax Vaccines in the 21st Century

Vaccination against Bacillus anthracis is the best preventive measure against the development of deadly anthrax disease in the event of exposure to anthrax either as a bioweapon or in its naturally occurring form. Anthrax vaccines, however, have historically been plagued with controversy, particularly related to their safety. Fortunately, recent improvements in anthrax vaccines have been shown to confer protection with reduced short-term safety concerns, although questions about long-term safety remain. Here, we (a) review recent and ongoing advances in anthrax vaccine development, (b) emphasize the need for thorough characterization of current (and future) vaccines, (c) bring to focus the importance of host immunogenetics as the ultimate determinant of successful antibody production and protection, and (d) discuss the need for the systematic, active, and targeted monitoring of vaccine recipients for possible Chronic Multisymptom Illness (CMI).

Association between brain cancer immunogenetic profile and in silico immunogenicities of 11 viruses

Several viruses including human herpes viruses (HHVs), human polyomavirus JCV, and human papilloma virus (HPV) have been implicated in brain cancer, albeit inconsistently. Since human leukocyte antigen (HLA) is centrally involved in the human immune response to viruses and has been implicated in brain cancer, we evaluated in silico the immunogenicity between 69 Class I HLA alleles with epitopes of proteins of 9 HHVs, JCV, and HPV with respect to a population-based HLA-brain cancer profile. We found that immunogenicity varied widely across HLA alleles with HLA-C alleles exhibiting the highest immunogenicity, and that immunogenicity scores were negatively associated with the population-based HLA-brain cancer profile, particularly for JCV, HHV6A, HHV5, HHV3, HHV8, and HHV7. Consistent with the role of HLA in foreign antigen elimination, the findings suggest that viruses with proteins of high HLA immunogenicity are eliminated more effectively and, consequently, less likely to cause brain cancer; conversely, the absence of highly immunogenic HLA may allow the viral antigens to persist, contributing to cancer.

Positive Association Between the Immunogenetic Human Leukocyte Antigen (HLA) Profiles of Multiple Sclerosis and Brain Cancer

Previous research has documented elevated risk of brain cancer in patients with multiple sclerosis (MS). Separately, human leukocyte antigen (HLA) has been implicated in protection or susceptibility for both conditions. The aim of the current study was to assess a possible role of shared immunogenetic influence on risk of MS and brain cancer. We first identified an immunogenetic profile for each condition based on the covariance between the population frequency of 127 high-resolution HLA alleles and the population prevalence of each condition in 14 Continental Western European countries and then evaluated the correspondence between MS and brain cancer immunogenetic profiles. Also, since each individual carries 12 HLA alleles (2 × 6 genes), we estimated HLA protection and susceptibility for MS and brain cancer at the individual level. We found that the immunogenetic profiles of MS and brain cancer were highly correlated overall (P < .001) and across all 6 HLA genes with the strongest association observed for DRB1, followed by DQB1 and HLA-A. These findings of immunogenetic overlap between MS and brain cancer are discussed in light of the role of HLA in the immune system response to viruses and other foreign antigens.

Changes of gray matter volumes of subcortical regions across the lifespan: a Human Connectome Project study

We assessed changes in gray matter volume (GMV) of nine subcortical regions (accumbens, amygdala, brainstem, caudate, cerebellar cortex, pallidum, putamen, thalamus, and ventral diencephalon) across the lifespan in a large sample of participants in the Human Connectome Project (n = 2,458, 5-90 yr old, 1,113 males and 1,345 females). 3T MRI data were acquired using a harmonized protocol and were processed in an identical way for all brains. GMVs of individual regions were adjusted for estimated total intracranial volume and regressed against age. We found highly statistically significant changes in GMV with age (P < 0.001) that were distinct among areas and mostly consistent between sexes, as follows. 1) The GMVs of accumbens, caudate, putamen, and cerebellum decreased with age in a linear fashion. The rate of decrease was steeper in males than in females for all regions. 2) The GMVs of the amygdala, pallidum, thalamus, ventral diencephalon, and brainstem changed with age in a quadratic fashion, i.e., increasing first and decreasing afterward. The estimated age at the peak (vertex) of the parabola was 51.8 yr for the brainstem and 28.0-37.9 yr for the other regions. The peak occurred earlier in males than in females, by an average of 8 yr, with the exception of the brainstem, where the age at the peak was very similar in both sexes. These results confirm previous findings and offer new insights into region-specific age-related changes in subcortical brain GMVs.NEW & NOTEWORTHY We report mixed effects of age on subcortical grey matter volume (GMV) during lifespan (n = 2458, 5-90 yr old, 1113 male, 1345 female). Striatal and cerebellar GMVs decreased linearly with age, more steeply in males. In contrast, GMVs of the amygdala, pallidum, thalamus, ventral diencephalon, and brainstem changed in a quadratic fashion, increasing first and decreasing afterward, with males peaking earlier than females in all regions but the brainstem where they peaked at nearly the same time.

Negative association between multiple sclerosis immunogenetic profile and in silico immunogenicities of 12 viruses

Human Leukocyte Antigen (HLA) is involved in both multiple sclerosis (MS) and immune response to viruses. Here we investigated the virus-HLA immunogenicity (V-HLA) of 12 viruses implicated in MS with respect to 17 HLA Class I alleles positively associated to MS prevalence in 14 European countries. Overall, higher V-HLA immunogenicity was associated with smaller MS-HLA effect, with human herpes virus 3 (HHV3), JC human polyoma virus (JCV), HHV1, HHV4, HHV7, HHV5 showing the strongest association, followed by HHV8, HHV6A, and HHV6B (moderate association), and human endogenous retrovirus (HERV-W), HHV2, and human papilloma virus (HPV) (weakest association). These findings suggest that viruses with proteins of high HLA immunogenicity are eliminated more effectively and, consequently, less likely to be involved in MS.

Changes of cortical gray matter volume during development: A Human Connectome Project study

We assessed changes in gray matter volume of 35 cerebrocortical regions in a large sample of participants in the Human Connectome Project-Development (n=649, 6-21 y old, 299 males and 350 females). The same protocol for MRI data acquisition and processing was employed for all brains. Volumes of individual areas were adjusted for estimated total intracranial volume and linearly regressed against age. We found changes of volume with age that were distinct among areas and consistent between sexes, as follows. (a) The overall cortical volume decreased significantly with age; (b) the volumes of 30/35 areas also decreased significantly with age; (c) the volumes of the hippocampal cortex (hippocampus, parahippocampal, and entorhinal) and that of pericalcarine cortex did not show significant age-related changes; and (d) the volume of the temporal pole increased significantly with age. The rates of volume reduction with age did not differ significantly between the two sexes, except for areas of the parietal lobe where males showed statistically significantly higher volume reduction with age than females. These results, obtained from a large sample of male and female participants, and acquired and processed in the same way, confirm previous findings, offer new insights into region-specific age-related changes in cortical brain volume, and are discussed in the context of the hypothesis that reduction in cortical volume may be partly due to a background, low-grade chronic neuroinflammation inflicted by common viruses residing latently in the brain, notably viruses of the human herpes family.

Risk assessment of substance use disorders based on the human leukocyte antigen (HLA)

Substance use disorders (SUDs) are common and costly conditions that are partially attributable to genetic factors. In light of immune system influences on neural and behavioral aspects of addiction, the present study evaluated the influence of genes involved in the human immune response, human leukocyte antigen (HLA), on SUDs. We used an immunogenetic epidemiological approach to evaluate associations between the population frequencies of 127 HLA alleles and the population prevalences of six SUDs (alcohol, amphetamine, cannabis, cocaine, opioid, and "other" dependence) in 14 countries of Continental Western Europe to identify immunogenetic profiles of each SUD and evaluate their associations. The findings revealed two primary groupings of SUDs based on their immunogenetic profiles: one group comprised cannabis and cocaine, whereas the other group comprised alcohol, amphetamines, opioids, and "other" dependence. Since each individual possesses 12 HLA alleles, the population HLA-SUD scores were subsequently used to estimate individual risk for each SUD. Overall, the findings highlight similarities and differences in immunogenetic profiles of SUDs that may influence the prevalence and co-occurrence of problematic SUDs and may contribute to assessment of SUD risk of an individual on the basis of their HLA genetic makeup.

Melanoma and Human Leukocyte Antigen (HLA): Immunogenicity of 69 HLA Class I Alleles With 11 Antigens Expressed in Melanoma Tumors

Host immunogenetics play a critical role in the human immune response to melanoma, influencing both melanoma prevalence and immunotherapy outcomes. Beneficial outcomes that stimulate T cell response hinge on binding affinity and immunogenicity of human leukocyte antigen (HLA) with melanoma antigen epitopes. Here, we use an in silico approach to characterize binding affinity and immunogenicity of 69 HLA Class I human leukocyte antigen alleles to epitopes of 11 known melanoma antigens. The findings document a significant proportion of positively immunogenic epitope-allele combinations, with the highest proportions of positive immunogenicity found for the Q13072/BAGE1 melanoma antigen and alleles of the HLA B and C genes. The findings are discussed in terms of a personalized precision HLA-mediated adjunct to immune checkpoint blockade immunotherapy to maximize tumor elimination.

Differential reduction of gray matter volume with age in 35 cortical areas in men (more) and women (less)

It is known that brain volume decreases with age. Here, we assessed the rate of this decrease in gray matter volume of 35 cortical regions in a large sample of healthy participants (n = 712, age range 36-90 yr) of the Human Connectome Project-Aging. We evaluated the difference in this rate between men (n = 316) and women (n = 396) and found that the volumes of cortical areas decreased by an average of 5.25%/decade, with the highest rate of decrease observed in the rostral anterior cingulate cortex (7.28%/decade). The rate of decrease was higher in men than in women in general and in 30/35 (85.7%) areas in particular, involving most prominently the cingulate lobe. These findings could serve as a normative reference for clinical conditions that manifest with abnormal brain atrophy.NEW & NOTEWORTHY This study showed an overall decrease of cortical gray matter with age but with different rates of volume reduction in different areas, with smaller decrease rates in women than in men. The highest volume reduction rate was observed for the rostral anterior cingulate cortex, an area linked to depression. These findings could serve as a normative reference for clinical conditions that manifest with abnormal brain atrophy.

Dependence of cognitive ability on synchronous neural interactions determined by magnetoencephalography (MEG)

Previous studies have shown that synchronous neural interactions (SNI) underlying healthy brain function can be readily distinguished from neural anomalies associated with diseases including dementia; however, it is imperative to identify biomarkers that facilitate early identification of individuals at risk for cognitive decline prior to the onset of clinical symptoms. Here we evaluated whether variation in brain activity, measured directly with magnetoencephalography, corresponds with subtle differences in cognitive performance in cognitively healthy women. A total of 251 women (age range 24-102 y) who performed above established cutoffs on the Montreal Cognitive Assessment (MoCA) also underwent a task-free magnetoencephalography scan from which SNI were computed. The results demonstrated that increased SNI was significantly associated with decreased cognitive performance (, controlling for age. Compared to the lowest performers with normal cognition (MoCA = 26), SNI of the highest performers (MoCA = 30) was associated with decorrelation primarily in the right anterior temporal cortex region, with additional (weaker) foci in the left anterior temporal cortex, right posterior temporal cortex, and cerebellum. These findings highlight the relevance of neural network decorrelation on cognitive functioning and suggest that subtle increases in SNI may presage future cognitive impairment.

Immunogenetic Profiles and Associations of Breast, Cervical, Ovarian, and Uterine Cancers

It is increasingly recognized that the human immune response influences cancer risk, progression, and survival; consequently, there is growing interest in the role of human leukocyte antigen (HLA), genes that play a critical role in initiating the immune response, on cancer. Recent evidence documented clustering of cancers based on immunogenetic profiles such that breast and ovarian cancers clustered together as did uterine and cervical cancers. Here we extend that line of research to evaluate the HLA profile of those 4 cancers and their associations. Specifically, we evaluated the associations between the frequencies of 127 HLA alleles and the population prevalences of breast, ovarian, cervical, and uterine cancer in 14 countries in Continental Western Europe. Factor analysis and hierarchical clustering were used to evaluate groupings of cancers based on their immunogenetic profiles. The results documented highly similar immunogenetic profiles for breast and ovarian cancers that were characterized predominantly by protective HLA effects. In addition, highly similar immunogenetic profiles for cervical and uterine cancers were observed that were, conversely, characterized by susceptibility effects. In light of the role of HLA in host immune system protection against non-self antigens, these findings suggest that certain cancers may be associated with similar contributory factors such as viral oncoproteins or neoantigens.

Human Leukocyte Antigen (HLA) Modulates the Dependence on Age of the Variability of Synchronous Neural Interactions

Recent evidence documented a protective effect of Class II human leukocyte antigen (HLA) DRB1*13 on brain health across the lifespan including evidence of reduced neural network variability relative to non-carriers. Here, in an extension of those findings, we evaluated the influence of a large number of Class I and Class II HLA alleles on aging-related changes in neural network variability. Cognitively healthy women (N = 178) ranging in age from 28 to 99 years old underwent a magnetoencephalography scan from which neural network variability was calculated and provided a blood sample from which HLA and apolipoprotein E (ApoE) genotype were determined. The primary analyses assessed the dependence of network variability on age in carriers of a specific HLA allele compared to non-carriers. Effects were considered protective if there was a significant increase of network variability with age in the absence of a given HLA allele but not in its presence, and were considered to confer susceptibility if the converse was documented; HLA alleles that did not influence the dependence of network variability on age in their presence or absence were considered neutral. Of 50 alleles investigated, 22 were found to be protective, 7 were found to confer susceptibility, and 21 were neutral. The frequencies of those 50 alleles were not associated significantly with ApoE genotype. The findings, which document the influence of HLA on age-related brain changes and highlight the role of HLA in healthy brain function, are discussed in terms of the role of HLA in the human immune response to foreign antigens.

Schizophrenia, Human Leukocyte Antigen (HLA), and Herpes Viruses: Immunogenetic Associations at the Population Level

Several factors have been implicated in schizophrenia (SZ), including human herpes viruses (HHV) and the adaptive immunity Human Leukocyte Antigen (HLA) genes. Here we investigated these issues in 2 complementary ways. In one analysis, we evaluated SZ-HLA and HHV-HLA associations at the level of a single allele by computing (a) a SZ-HLA protection/susceptibility (P/S) score based on the covariance between SZ and 127 HLA allele prevalences in 14 European countries, (b) estimating in silico HHV-HLA best binding affinities for the 9 HHV strains, and (c) evaluating the dependence of P/S score on HHV-HLA binding affinities. These analyses yielded (a) a set of 127 SZ-HLA P/S scores, varying by >200× (maximum/minimum), which could not be accounted for by chance, (b) a set of 127 alleles × 9 HHV best-estimated affinities, varying by >600×, and (c) a set of correlations between SZ-HLA P/S scores and HHV-HLA binding which indicated a prominent role of HHV1. In a subsequent analysis, we extended these findings to the individual person by taking into account the fact that every individual carries 12 HLA alleles and computed (a) the average SZ-HLA P/S scores of 12 randomly chosen alleles (2 per gene), an indicator of HLA-based SZ P/S for an individual, and (b) the average of the corresponding HHV estimated affinities for those alleles, an indicator of overall effectiveness of HHV-HLA binding. We found (a) that HLA protection for SZ was significantly more prominent than susceptibility, and (b) that protective SZ-HLA scores were associated with higher HHV-HLA binding affinities, indicating that HLA binding and subsequent elimination of several HHV strains may confer protection against schizophrenia.

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.

Heritability of brain neurovascular coupling

The moment-to-moment variation of neurovascular coupling in the brain was determined by computing the moment-to-moment turnover of the blood-oxygen-level-dependent signal (TBOLD) at resting state. Here we show that 1) TBOLD is heritable, 2) its heritability estimates are highly correlated between left and right hemispheres, and 3) the degree of its heritability is determined, in part, by the anatomical proximity of the brain areas involved. We also show that the regional distribution of TBOLD in the cortex is significantly associated with that of the vesicular acetylcholine transporter. These findings establish that TBOLD as a key heritable measure of local cortical brain function captured by neurovascular coupling.NEW & NOTEWORTHY Here we show that the sample-to-sample turnover of the resting state fMRI blood-oxygen-level-dependent turnover (TBOLD) is heritable, the left and right hemisphere TBOLD heritabilities are highly correlated, and TBOLD heritability varies among cortical areas. Moreover, we documented that TBOLD is associated with the regional cortical distribution of the vesicular acetylcholine transporter.

Reply to the Letter to the Editor by Sipila, Jussi

This a Reply to the Letter to the Editor by Sipila, Jussi regarding our article titled: James LM, Georgopoulos AP. High Correlations Among Worldwide Prevalences of Dementias, Parkinson’s Disease, Multiple Sclerosis, and Motor Neuron Diseases Indicate Common Causative Factors. Neurosci Insights. 2022 Aug 8;17:26331055221117598. doi: 10.1177/26331055221117598.

The dynamic shaping of local cortical circuitry by sex and age, and its relation to Pattern Comparison Processing Speed

Previous resting-state functional magnetic resonance imaging (fMRI) studies have shown that the strength of local neural interactions decreases with distance. Here we extend that line of research to evaluate effects of sex and age on local cortical circuitry in 6 cortical areas (superior frontal, precentral, postcentral, superior parietal, inferior parietal, lateral occipital) using data acquired from 1,054 healthy young adults who participated in the Human Connectome Project. We confirmed previous findings that the strength of zero-lag correlations between prewhitened, resting-state, blood level oxygenation-dependent (BOLD) fMRI time series decreased with distance locally, and documented that the rate of decrease with distance ("spatial steepness") (a) was progressively lower from anterior to posterior areas, (b) was greater in women, especially in anterior areas, (c) increased with age, particularly for women, (d) was significantly correlated with percent inhibition, and (e) was positively and highly significantly correlated with pattern comparison processing speed (PCPS). A hierarchical tree clustering analysis of this dependence of PCPS on spatial steepness revealed a differential organization in processing that information between the two hemispheres, namely a more independent vs. a more integrative processing in the left and right hemispheres, respectively. These findings document sex and age differences in dynamic local cortical interactions, and provide evidence that spatial sharpening of these interactions may underlie cognitive processing speed differently organized in the two hemispheres.

MEG neural signature of sexual trauma in women veterans with PTSD

Previous research has documented the utility of synchronous neural interactions (SNI) in classifying women veterans with and without posttraumatic stress disorder (PTSD) and other trauma-related outcomes based on functional connectivity using magnetoencephalography (MEG). Here, we extend that line of research to evaluate trauma-specific PTSD neural signatures with MEG in women veterans. Participants completed diagnostic interviews and underwent a task-free MEG scan from which SNI was computed. Thirty-five women veterans were diagnosed with PTSD due to sexual trauma and sixteen with PTSD due to non-sexual trauma. Strength of SNI was compared in women with and without sexual trauma, and linear discriminant analysis was used to classify the brain patterns of women with PTSD due to sexual trauma and non-sexual trauma. Comparison of SNI strength between the two groups revealed widespread hypercorrelation in women with sexual trauma relative to those without sexual trauma. Furthermore, using SNI, the brains of participants were classified as sexual trauma or non-sexual trauma with 100% accuracy. These findings bolster evidence supporting the utility of task-free SNI and suggest that neural signatures of PTSD are trauma-specific.

BOLD turnover in task-free state: variation among brain areas and effects of age and human leukocyte antigen (HLA) DRB1*13

Blood oxygen level dependent (BOLD) signal in functional magnetic resonance imaging (fMRI) is frequently used as a proxy for underlying neural activity. Although this is a plausible assumption for experiments where a task is performed, it may not hold to the same degree for conditions of fMRI recording in a task-free, "resting" state where neural synaptic events are weak and, hence, neurovascular coupling and endothelial vascular factors become more prominent (Hillman Annu Rev Neurosci 37:161-181, 2014, 10.1146/annurev-neuro-071013-014111). Here we investigated the magnitude of change of BOLD in consecutive samples over the acquisition time period (turnover of BOLD, "TBOLD") by first-order differencing of single-voxel BOLD time series acquired in 70 areas of the cerebral cortex of 57 cognitively healthy women in a task-free resting state. More specifically, we evaluated (a) the variation of TBOLD among different cortical areas, (b) its dependence on age, and (c) its dependence on the presence (or absence) of the neuroprotective Human Leukocyte Antigen (HLA) gene DRB1*13 (DRB1*13:02 and DRB1*13:01). We found that TBOLD (a) varied substantially by 2.2 × among cortical areas, being highest in parahippocampal and entorhinal areas and lowest in parietal-occipital areas, (b) was significantly reduced in DRB1*13 carriers across cortical areas (from ~ 15% reduction in orbitofrontal cortex to 2% reduction in cuneus), and (c) increased with age in noncarriers of DRB1*13 but decreased with age in DRB1*13 carriers. These findings document significant dependencies of TBOLD on cortical area location, HLA DRB1*13 and age.

SARS-CoV-2 in silico binding affinity to human leukocyte antigen (HLA) Class II molecules predicts vaccine effectiveness across variants of concern (VOC)

There is widespread concern about the clinical effectiveness of current vaccines in preventing Covid-19 caused by SARS-CoV-2 Variants of Concern (Williams in Lancet Respir Med 29:333-335, 2021; Hayawi in Vaccines 9:1305, 2021), including those identified at present (Alpha, Beta, Gamma, Delta, Omicron) and possibly new ones arising in the future. It would be valuable to be able to predict vaccine effectiveness for any variant. Here we offer such an estimate of predicted vaccine effectiveness for any SARS-CoV-2 variant based on the amount of overlap of in silico high binding affinity of the variant and Wildtype spike glycoproteins to a pool of frequent Human Leukocyte Antigen Class II molecules which are necessary for initiating antibody production (Blum et al. in Annu Rev Immunol 31:443-473, 2013). The predictive model was strong (r = 0.910) and statistically significant (P = 0.013).

Immunogenetic clustering of 30 cancers

Human leukocyte antigen (HLA) genes have been implicated in cancer risk and shared heritability of different types of cancer. In this immunogenetic epidemiological study we first computed a Cancer-HLA profile for 30 cancer types characterized by the correlation between the prevalence of each cancer and the population frequency of 127 HLA alleles, and then used multidimensional scaling to evaluate the possible clustering of those Cancer-HLA associations. The results indicated the presence of three clusters, broadly reflecting digestive-skin-cervical cancers, reproductive and endocrine systems cancers, and brain and androgen-associated cancers. The clustering of cancer types documented here is discussed in terms of mechanisms underlying shared Cancer-HLA associations.

Orexin enhances neuronal synchronization in adult rat hypothalamic culture: a model to study hypothalamic function

The regulation of sleep/wake behavior and energy homeostasis is maintained in part by the hypothalamic neuropeptide orexin A (OXA, hypocretin). Reduction in orexin signaling is associated with sleep disorders and obesity, whereas higher lateral hypothalamic (LH) orexin signaling and sensitivity promotes obesity resistance. Similarly, dysregulation of hypothalamic neural networks is associated with onset of age-related diseases, including obesity and several neurological diseases. Despite the association of obesity and aging, and that adult populations are the target for the majority of pharmaceutical and obesity studies, conventional models for neuronal networks utilize embryonic neural cultures rather than adult neurons. Synchronous activity describes correlated changes in neuronal activity between neurons and is a feature of normal brain function, and is a measure of functional connectivity and final output from a given neural structure. Earlier studies show alterations in hypothalamic synchronicity following behavioral perturbations in embryonic neurons obtained from obesity-resistant rats and following application of orexin onto embryonic hypothalamic cultures. Synchronous network dynamics in adult hypothalamic neurons remain largely undescribed. To address this, we established an adult rat hypothalamic culture in multi-electrode-array (MEA) dishes and recorded the field potentials. Then we studied the effect of exogenous orexin on network synchronization of these adult hypothalamic cultures. In addition, we studied the wake promoting effects of orexin in vivo when directly injected into the lateral hypothalamus (LH). Our results showed that the adult hypothalamic cultures are viable for nearly 3 mo in vitro, good quality MEA recordings can be obtained from these cultures in vitro, and finally, that cultured adult hypothalamus is responsive to orexin. These results support that adult rat hypothalamic cultures could be used as a model to study the neural mechanisms underlying obesity. In addition, LH administration of OXA enhanced wakefulness in rats, indicating that OXA enhances wakefulness partly by promoting neural synchrony in the hypothalamus.NEW & NOTEWORTHY This study, for the first time, demonstrates that adult hypothalamic cultures are viable in vitro for a prolonged duration and are electrophysiologically active. In addition, the study shows that orexin enhances neural synchronization in adult hypothalamic cultures.

Classification of posttraumatic stress disorder and related outcomes in women veterans using magnetoencephalography

Women veterans represent a unique population whose experiences and neurobiology differ from that of their male counterparts. Thus, while previous research has demonstrated the utility of synchronous neural interactions (SNI) as a biomarker of posttraumatic stress disorder (PTSD) in male veterans, the utility of SNI as a biomarker of PTSD in women veterans is unclear. Here we extend that line of research to evaluate classification of women veterans with and without PTSD and other trauma-related outcomes based on functional connectivity using magnetoencephalography (MEG). A total of 121 U.S. women veterans completed diagnostic interviews and underwent a task-free MEG scan from which SNI was computed. Linear discriminant analysis was used to classify PTSD and control groups according to SNI. That discriminant function was then used to classify each individual in the partial recovery and full recovery diagnostic groups as PTSD or control. All individuals were classified correctly (100% accuracy) according to their SNI in their PTSD and control groups. Seventy-seven percent of the full recovery group and 69% of the partial recovery group were classified as control. Individual staging in PTSD recovery was captured by the Mahalanobis D² distances from the center of the control and PTSD centroid clusters. These findings provide compelling evidence supporting the utility of task-free SNI as a biomarker of PTSD and related outcomes in women veterans.

At the Root of 3 “Long” Diseases: Persistent Antigens Inflicting Chronic Damage on the Brain and Other Organs in Gulf War Illness, Long-COVID-19, and Chronic Fatigue Syndrome

Several foreign antigens such as those derived from viruses and bacteria have been linked to long-term deleterious effects on the brain and other organs; yet, health outcomes subsequent to foreign antigen exposure vary depending in large part on the host’s immune system, in general, and on human leukocyte antigen (HLA) composition, in particular. Here we first provide a brief description of 3 conditions characterized by persistent long-term symptoms, namely long-COVID-19, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and Gulf War Illness (GWI), followed by a brief overview of the role of HLA in the immune response to foreign antigens. We then discuss our Persistent Antigen (PA) hypothesis and highlight associations between antigen persistence due to HLA-antigen incongruence and chronic health conditions in general and the 3 “long” diseases above in particular. This review is not intended to cover the breadth and depth of symptomatology of those diseases but is specifically focused on the hypothesis that the presence of persistent antigens underlies their pathogenesis.

High Correlations Among Worldwide Prevalences of Dementias, Parkinson’s Disease, Multiple Sclerosis, and Motor Neuron Diseases Indicate Common Causative Factors

Dementia, Parkinson’s disease, multiple sclerosis, and motor neuron diseases cause significant disability and mortality worldwide. Although the etiology of these diseases is unknown, highly correlated disease prevalences would indicate the involvement of common etiologic factors. Here we used published epidemiological data in 195 countries worldwide to investigate the possible intercorrelations among the prevalences of these diseases. All analyses were carried out using nonparametric statistics on rank-transformed data to assure the robustness of the results. We found that all 6 pairwise correlations among the prevalences of the 4 diseases were very high (>.9, P < .001). A factor analysis (FA) yielded only a single component which comprised all 4 disease prevalences and explained 96.3% of the variance. These findings indicate common etiologic factor(s). Next, we quantified the contribution of 3 country-specific factors (population size, life expectancy, latitude) to the common grouping of prevalences by estimating the reduction in total FA variance explained when the effect of these factors was eliminated by using the prevalence residuals from a linear regression where theses factor were covariates. FA of these residuals yielded again only a single component comprising all 4 diseases which explained 71.5% of the variance, indicating that the combined contribution of population size, life expectancy and latitude accounted for 96.3% − 71.5% = 24.8% of the FA variance explained. The fact that the 3 country-specific factors above accounted for only 24.8% of the FA variance explained by the original (ranked) disease prevalences, in the presence still of a single grouping factor, strongly indicates the operation of other unknown factors jointly contributing to the pathogenesis of the 4 diseases. We discuss various possible factors involved, with an emphasis on biologic pathogens (viruses, bacteria) which have been implicated in the pathogenesis of these diseases in previous studies.

Behavioral-genetic associations in the Human Connectome Project

The Human Connectome Project (HCP) provides a rich dataset of quantitative and domain-specific behavioral measures from twins and extensive family structures. This makes the dataset a unique and a valuable resource to investigate heritability and determine individual differences. Using a set of measures of behavioral domains (motor, emotion, personality, sensory, and cognition), we estimated the intraclass correlations (ICCs) and heritability of 56 behavioral measures for 4 genetically identified groups of participants: monozygotic (MZ) twins, dizygotic (DZ) twins, non-twin siblings (SB), and unrelated individuals (NR). The ICCs range varied among behavioral domains but systematically so among the four genetic groups. We found the same rank order of ICCs, from the highest values for MZ twins, statistically significantly smaller for the DZ twins and sibling group (compared to MZ), and close to zero for NR. The mean heritability values of the five behavioral domains were: cognition h² = 0.405, emotion h² = 0.316, motor h² = 0.138, personality h² = 0.444, and sensory h² = 0.193. These domains share overlapping brain networks. The heritability of motor domain was significantly smaller than cognitive, personality, and emotion domains. These findings provide new insight into the effect of genetics on the various diverse behavioral measures.

In silico assessment of binding affinities of three dementia-protective Human Leukocyte Antigen (HLA) alleles to nine human herpes virus antigens

BACKGROUND

Human herpes viruses (HHV) have been implicated in dementia. Class II Human Leukocyte Antigens (HLA) play a critical role in host protection from foreign antigens including herpes viruses through stimulating antibody production against them. In the present study we investigated the in silico binding affinity of 9 H HV to three Class II HLA alleles that have been found to protect against dementia: DRB1*01:01, DRB1*13:02, and DRB1*15:01.

METHODS

A sliding window approach was used to partition the amino acid sequences of surface glycoproteins from HHV 1-8 into subsequences. The binding affinity of the HHV subsequences to Class II HLA surface receptor proteins was predicted using the Sturniolo method in the Immune Epitope Database and reported as a percentile rank. The binding affinity of HHV subsequences to protective alleles was compared to that of three dementia-neutral Class II HLA alleles: DRB1*03:01, DRB1*07:01, and DRB1*08:01.

FINDINGS

Binding affinity varied widely for each HLA allele, HHV type, and HHV subsequence. The protective alleles had significantly higher binding affinity that than the neutral alleles. The largest differences in binding affinity between the protective and neutral alleles was shown for HHV-6A and HHV-6B, which had the best overall binding affinity with the protective alleles.

INTERPRETATION

The dementia protection conferred by the three protective HLA alleles investigated here is related to their superior ability to bind and successfully eliminate HHV epitopes - in particular, HHV6 - that could otherwise cause dementia if they persisted.

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.

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.

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.

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.

Invariant and heritable local cortical organization as revealed by fMRI

Neural interactions in local cortical networks critically depend on the distance between interacting elements: the shorter the distance, the stronger the interactions. Here we quantified these interactions in six cortical areas of 854 individuals, including monozygotic and dizygotic twins, nontwin siblings, and nonrelated individuals. We found that the strength of zero-lag correlation between prewhitened, resting-state, blood level oxygenation-dependent functional magnetic resonance imaging time series decreased with distance as a power law. The rate of decrease, b, varied among individuals by ~1.9×, was highly correlated between hemispheres, but differed among areas (by ~1.2×) in a systematic fashion, becoming progressively less steep from frontal to occipital areas. With respect to twin status, b was significantly correlated between monozygotic twins, less so between dizygotic twins or nontwin siblings, and not at all in nonrelated individuals. These results quantify the lawful, distance-related cortical interactions and demonstrate, for the first time, the heritability of their power law. NEW & NOTEWORTHY Local cortical circuitry involves orderly neuronal interactions. A key feature of these interactions is that they are stronger the closer the interacting neurons. Here we quantified this crucial dependence of neural interactions on distance with functional magnetic resonance imaging and found that the strength of interactions decreases with distance as a power law that is very similar in all cortical lobes and heritable. These findings identify an invariant and heritable property of local cortical organization.

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.

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.

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 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.

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Subcortical brain atrophy is spared in Gulf War veterans with DRB1*13:02 allele and unaffected by the DRB1*13:01 allele.

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The strongest protective effect of the DRB1*13:02 allele was observed for cerebellar gray matter volume.

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No significant effects were observed at the DRB1*13 gene level, highlighting the importance of 4-digit HLA protein level.

Gulf War Illness (GWI) is a chronic, debilitating disorder that prominently involves the brain and is characterized, in particular, by subcortical brain atrophy. Protective effects of specific Human Leukocyte Antigen (HLA) Class II alleles on GWI have been observed, suggesting immune system involvement in GWI. Here we evaluated protective effects of DRB1*13:02 on subcortical brain volume in Gulf War veterans. The results demonstrate a protective effect of DRB1*13:02 on brain atrophy, with a marked effect on cerebellar gray matter volume. Given the goal of HLA Class II alleles is to eliminate pathogens by producing antibodies against them, the present study provides compelling insights into the likely role of persistent, pathogenic antigens resulting from the absence of DRB1*13:02 in those with GWI.

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).

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.

Cortical miscommunication after prenatal exposure to alcohol

We report on the effects of prenatal alcohol exposure on resting-state brain activity as measured by magnetoencephalography (MEG). We studied 37 subjects diagnosed with fetal alcohol spectrum disorder in one of three categories: fetal alcohol syndrome, partial fetal alcohol syndrome, and alcohol-related neurodevelopmental disorder. For each subject, the MEG signal was recorded for 60 s during rest while subjects lay supine. Using time series analysis, we calculated the synchronous neural interactions for all pair-wise combinations of 248 MEG sensors resulting in 30,628 partial correlations for each subject. We found significant differences from control subjects in 6.19 % of the partial zero-lag crosscorrelations (synchronous neural interactions; Georgopoulos et al. in J Neural Eng 4:349-355, 2007), with these differences localized in the right posterior frontal, right parietal, and left parietal/posterior frontal regions. These results show that MEG can detect functional brain differences in the individuals affected by prenatal exposure to alcohol. Furthermore, these differences may serve as a biomarker for future studies linking symptoms and signs to specific brain areas. This may lead to new insights into the neuropathology of fetal alcohol spectrum disorders.

The Number of Cysteine Residues per Mole in Apolipoprotein E Is Associated With the Severity of PTSD Re-Experiencing Symptoms

Apolipoprotien E (ApoE) is involved in critical neural functions and is associated with various neuropsychiatric disorders. ApoE exists in three isoforms that differ in the number of cysteine residues per mole (CysR/mole). This study evaluated associations between this informative ordinal biochemical scale (CysR/mole) and symptom severity in veterans with posttraumatic stress disorder (PTSD) or subthreshold PTSD. Results demonstrated a significant negative relationship between the CysR/mole and severity of PTSD re-experiencing symptoms, adjusted for trauma. The findings suggest a genetic influence on PTSD symptomatology and dovetail with recent advances regarding the molecular mechanisms underlying the differential effects of ApoE in the brain.

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.

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Differences in Human Leukocyte Antigen distinguished veterans with Gulf War Illness (GWI) from healthy Gulf War era veterans.

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Veterans with GWI show genetic susceptibility which is associated with increased severity of hallmark symptoms of GWI.

A large number of Gulf War veterans suffer from diffuse and debilitating symptoms that resemble altered immune functioning. This study evaluated whether the Human Leukocyte Antigen (HLA) gene, which is central to immune functioning, differs between veterans with GWI and unaffected Gulf War veterans. The findings highlight robust differences in HLA composition between the two groups and suggest that veterans with GWI are characterized by genetic susceptibility that confers risk for typical GWI symptoms. These findings provide compelling genetic evidence of immune dysfunction in GWI.