T-cell infiltration, contribution and regulation in the central nervous system post-traumatic injury.

T cells participate in the repair process and immune response in the CNS post-traumatic injury and play both a beneficial and harmful role. Together with nerve cells and other immune cells, they form a microenvironment in the CNS post-traumatic injury. The repair of traumatic CNS injury is a long-term process. T cells contribute to the repair of the injury site to influence the recovery. Recently, with the advance of new techniques, such as mass spectrometry-based flow cytometry, modern live-cell imaging, etc, research focusing on T cells is becoming one of the valuable directions for the future therapy of traumatic CNS injury. In this review, we summarized the infiltration, contribution and regulation of T cells in post-traumatic injury, discussed the clinical significance and predicted the future research direction.

COVID-19 patient transcriptomic and genomic profiling reveals comorbidity interactions with psychiatric disorders.

Psychiatric symptoms are seen in some COVID-19 patients, as direct or indirect sequelae, but it is unclear whether SARS-CoV-2 infection interacts with underlying neuronal or psychiatric susceptibilities. Such interactions might arise from COVID-19 immune responses, from infection of neurons themselves or may reflect social-psychological causes. To clarify this we sought the key gene expression pathways altered in COVID-19 also affected in bipolar disorder, post-traumatic stress disorder (PTSD) and schizophrenia, since this may identify pathways of interaction that could be treatment targets. We performed large scale comparisons of whole transcriptome data and immune factor transcript data in peripheral blood mononuclear cells (PBMC) from COVID-19 patients and patients with psychiatric disorders. We also analysed genome-wide association study (GWAS) data for symptomatic COVID-19 patients, comparing GWAS and whole-genome sequence data from patients with bipolar disorder, PTSD and schizophrenia patients. These studies revealed altered signalling and ontology pathways shared by COVID-19 patients and the three psychiatric disorders. Finally, co-expression and network analyses identified gene clusters common to the conditions. COVID-19 patients had peripheral blood immune system profiles that overlapped with those of patients with psychiatric conditions. From the pathways identified, PTSD profiles were the most highly correlated with COVID-19, perhaps consistent with stress-immune system interactions seen in PTSD. We also revealed common inflammatory pathways that may exacerbate psychiatric disorders, which may support the usage of anti-inflammatory medications in these patients. It also highlights the potential clinical application of multi-level dataset studies in difficult-to-treat psychiatric disorders in this COVID-19 pandemic.

Microglial deletion and inhibition alleviate behavior of post-traumatic stress disorder in mice.

BACKGROUND: Alteration of immune status in the central nervous system (CNS) has been implicated in the development of post-traumatic stress disorder (PTSD). However, the nature of overall changes in brain immunocyte landscape in PTSD condition remains unclear. METHODS: We constructed a mouse PTSD model by electric foot-shocks followed by contextual reminders and verified the PTSD-related symptoms by behavior test (including contextual freezing test, open-field test, and elevated plus maze test). We examined the immunocyte panorama in the brains of the naïve or PTSD mice by using single-cell mass cytometry. Microglia number and morphological changes in the hippocampus, prefrontal cortex, and amygdala were analyzed by histopathological methods. The gene expression changes of those microglia were detected by quantitative real-time PCR. Genetic/pharmacological depletion of microglia or minocycline treatment before foot-shocks exposure was performed to study the role of microglia in PTSD development and progress. RESULTS: We found microglia are the major brain immune cells that respond to PTSD. The number of microglia and ratio of microglia to immunocytes was significantly increased on the fifth day of foot-shock exposure. Furthermore, morphological analysis and gene expression profiling revealed temporal patterns of microglial activation in the hippocampus of the PTSD brains. Importantly, we found that genetic/pharmacological depletion of microglia or minocycline treatment before foot-shock exposure alleviated PTSD-associated anxiety and contextual fear. CONCLUSION: Our results demonstrated a critical role for microglial activation in PTSD development and a potential therapeutic strategy for the clinical treatment of PTSD in the form of microglial inhibition.

High IL-6 in military personnel relates to multiple traumatic brain injuries and post-traumatic stress disorder.

Repetitive traumatic brain injuries (TBIs) among military personnel have been linked to chronic behavioral and neurological symptoms, and poor health outcomes. Repetitive TBIs may impact inflammation, which may offer some explanation of the biological basis of these long-term risks, and may improve the care that is provided to these individuals. This study examines the concentrations of TNFα, IL-6 and IL-10 and associations with behavioral symptoms, including post-traumatic stress disorder symptoms and depression in a cohort of 106 military personnel and Veterans with a history of TBI. Group comparisons conducted for those with repetitive TBIs (> 3; n = 44), to participants with less than three TBIs (n = 29), and controls with no TBIs (n = 33). The primary outcomes were serum levels of inflammatory related proteins TNF-α, IL-6 and IL-10, TBI history, and PTSD symptoms. IL-6 mean concentration was significantly higher in the repetitive TBI group compared to those with 1-2 TBI or no TBI history (p = 0.050). Additionally, for participants with a history of TBI, PTSD symptom severity, specifically, intrusion (p = .006 and p = .007) and avoidance (p = .034 and .009), were significant predictors of higher IL-6 and IL-10 concentrations respectively. These findings suggest that repetitive TBIs concurrent with high PTSD symptoms in military personnel and Veterans are associated with chronic inflammation, and specifically elevated concentrations of IL-6. Examining the changes in inflammatory processes may identify potential therapeutic targets for early intervention after TBI in order to prevent the development of neurological deficits and disorders.

Immediate psychological distress in quarantined patients with COVID-19 and its association with peripheral inflammation: A mixed-method study.

Since the end of 2019, Corona Virus Disease 2019 (COVID-19) has been the cause of a worldwide pandemic. The mental status of patients with COVID-19 who have been quarantined and the interactions between their psychological distress and physiological levels of inflammation have yet to be analyzed. Using a mixed-method triangulation design (QUAN + QUAL), this study investigated and compared the mental status and inflammatory markers of 103 patients who, while hospitalized with mild symptoms, tested positive with COVID-19 and 103 matched controls that were COVID-19 negative. The severity of depression, anxiety, and post-traumatic stress symptoms (PTSS) was measured via an on-line survey. Using a convenience sampling technique, qualitative data were collected until the point of data saturation. In addition, a semi-structured interview was conducted among five patients with COVID-19. Peripheral inflammatory markers were also collected in patients, both at baseline and within ± three days of completing the on-line survey. Results revealed that COVID-19 patients, when compared to non-COVID controls, manifested higher levels of depression (P < 0.001), anxiety (P < 0.001), and post-traumatic stress symptoms (P < 0.001). A gender effect was observed in the score of "Perceived Helplessness", the subscale of PSS-10, with female patients showing higher scores compared to male patients (Z = 2.56, P = 0.010), female (Z = 2.37, P = 0.018) and male controls (Z = 2.87, P = 0.004). Levels of CRP, a peripheral inflammatory indicator, correlated positively with the PHQ-9 total score (R = 0.37, P = 0.003, Spearman's correlation) of patients who presented symptoms of depression. Moreover, the change of CRP level from baseline inversely correlated with the PHQ-9 total score (R = -0.31, P = 0.002), indicative of improvement of depression symptoms. Qualitative analysis revealed similar results with respect to patient reports of negative feelings, including fear, guilt, and helplessness. Stigma and uncertainty of viral disease progression were two main concerns expressed by COVID-19 patients. Our results indicate that significant psychological distress was experienced by hospitalized COVID-19 patients and that levels of depressive features may be related to the inflammation markers in these patients. Thus, we recommend that necessary measures should be provided to address depression and other psychiatric symptoms for COVID-19 patients and attention should be paid to patient perceived stigma and coping strategies when delivering psychological interventions.

PTSD is associated with neuroimmune suppression: evidence from PET imaging and postmortem transcriptomic studies.

Despite well-known peripheral immune activation in posttraumatic stress disorder (PTSD), there are no studies of brain immunologic regulation in individuals with PTSD. [11C]PBR28 Positron Emission Tomography brain imaging of the 18-kDa translocator protein (TSPO), a microglial biomarker, was conducted in 23 individuals with PTSD and 26 healthy individuals-with or without trauma exposure. Prefrontal-limbic TSPO availability in the PTSD group was negatively associated with PTSD symptom severity and was significantly lower than in controls. Higher C-reactive protein levels were also associated with lower prefrontal-limbic TSPO availability and PTSD severity. An independent postmortem study found no differential gene expression in 22 PTSD vs. 22 controls, but showed lower relative expression of TSPO and microglia-associated genes TNFRSF14 and TSPOAP1 in a female PTSD subgroup. These findings suggest that peripheral immune activation in PTSD is associated with deficient brain microglial activation, challenging prevailing hypotheses positing neuroimmune activation as central to stress-related pathophysiology.

Role of enhanced glucocorticoid receptor sensitivity in inflammation in PTSD: insights from computational model for circadian-neuroendocrine-immune interactions.

Although glucocorticoid resistance contributes to increased inflammation, individuals with posttraumatic stress disorder (PTSD) exhibit increased glucocorticoid receptor (GR) sensitivity along with increased inflammation. It is not clear how inflammation coexists with a hyperresponsive hypothalamic-pituitary-adrenal (HPA) axis. To understand this better, we developed and analyzed an integrated mathematical model for the HPA axis and the immune system. We performed mathematical simulations for a dexamethasone (DEX) suppression test and IC50-dexamethasone for cytokine suppression by varying model parameters. The model analysis suggests that increasing the steepness of the dose-response curve for GR activity may reduce anti-inflammatory effects of GRs at the ambient glucocorticoid levels, thereby increasing proinflammatory response. The adaptive response of proinflammatory cytokine-mediated stimulatory effects on the HPA axis is reduced due to dominance of the GR-mediated negative feedback on the HPA axis. To verify these hypotheses, we analyzed the clinical data on neuroendocrine variables and cytokines obtained from war-zone veterans with and without PTSD. We observed significant group differences for cortisol and ACTH suppression tests, proinflammatory cytokines TNFα and IL6, high-sensitivity C-reactive protein, promoter methylation of GR gene, and IC50-DEX for lysozyme suppression. Causal inference modeling revealed significant associations between cortisol suppression and post-DEX cortisol decline, promoter methylation of human GR gene exon 1F (NR3C1-1F), IC50-DEX, and proinflammatory cytokines. We noted significant mediation effects of NR3C1-1F promoter methylation on inflammatory cytokines through changes in GR sensitivity. Our findings suggest that increased GR sensitivity may contribute to increased inflammation; therefore, interventions to restore GR sensitivity may normalize inflammation in PTSD.

Are we facing a crashing wave of neuropsychiatric sequelae of COVID-19? Neuropsychiatric symptoms and potential immunologic mechanisms.

The coronavirus disease 19 (COVID-19) pandemic is a significant psychological stressor in addition to its tremendous impact on every facet of individuals' lives and organizations in virtually all social and economic sectors worldwide. Fear of illness and uncertainty about the future precipitate anxiety- and stress-related disorders, and several groups have rightfully called for the creation and dissemination of robust mental health screening and treatment programs for the general public and front-line healthcare workers. However, in addition to pandemic-associated psychological distress, the direct effects of the virus itself (several acute respiratory syndrome coronavirus; SARS-CoV-2), and the subsequent host immunologic response, on the human central nervous system (CNS) and related outcomes are unknown. We discuss currently available evidence of COVID-19 related neuropsychiatric sequelae while drawing parallels to past viral pandemic-related outcomes. Past pandemics have demonstrated that diverse types of neuropsychiatric symptoms, such as encephalopathy, mood changes, psychosis, neuromuscular dysfunction, or demyelinating processes, may accompany acute viral infection, or may follow infection by weeks, months, or longer in recovered patients. The potential mechanisms are also discussed, including viral and immunological underpinnings. Therefore, prospective neuropsychiatric monitoring of individuals exposed to SARS-CoV-2 at various points in the life course, as well as their neuroimmune status, are needed to fully understand the long-term impact of COVID-19, and to establish a framework for integrating psychoneuroimmunology into epidemiologic studies of pandemics.

Dysregulation of inflammation, neurobiology, and cognitive function in PTSD: an integrative review.

Compelling evidence from animal and human research suggest a strong link between inflammation and posttraumatic stress disorder (PTSD). Furthermore, recent findings support compromised neurocognitive function as a key feature of PTSD, particularly with deficits in attention and processing speed, executive function, and memory. These cognitive domains are supported by brain structures and neural pathways that are disrupted in PTSD and which are implicated in fear learning and extinction processes. The disruption of these supporting structures potentially results from their interaction with inflammation. Thus, the converging evidence supports a model of inflammatory dysregulation and cognitive dysfunction as combined mechanisms underpinning PTSD symptomatology. In this review, we summarize evidence of dysregulated inflammation in PTSD and further explore how the neurobiological underpinnings of PTSD, in the context of fear learning and extinction acquisition and recall, may interact with inflammation. We then present evidence for cognitive dysfunction in PTSD, highlighting findings from human work. Potential therapeutic approaches utilizing novel pharmacological and behavioral interventions that target inflammation and cognition also are discussed.

Proinflammatory status-stratified blood transcriptome profiling of civilian women with PTSD.

Etiology of posttraumatic stress disorder (PTSD) remains largely unknown. Studies have shown that a significant subset of patients with PTSD exhibit increased inflammation, suggesting that the understanding of this disorder could be facilitated by classifying these patients by inflammatory status. Here we performed a microarray-based blood transcriptome analysis on proinflammatory status-stratified Japanese civilian women with PTSD most of whom developed the disorder after experiencing interpersonal violence. By utilizing our previously identified cut-off serum interleukin-6 (IL-6) level that approximately corresponded to the median IL-6 level of our PTSD patients, we classified patients into those with high IL-6 levels and those with normal IL-6 levels (n = 16 for each). Transcriptome profiles of these 2 groups were compared with the profile of 16 age-matched healthy control women. Differentially expressed genes between high IL-6 patients and controls showed significant enrichment in a number of gene ontology terms and pathways primarily involved in immune/inflammatory responses, and their protein-protein interaction network was significantly enriched. In contrast, differentially expressed genes between normal IL-6 patients and controls showed significant enrichment in several gene ontology terms related to ion transport and neural function. The microarray data were confirmed by reverse transcription quantitative PCR. These findings illustrate the heterogeneous molecular mechanisms of PTSD within this relatively homogeneous sample in terms of sex, trauma type, and ethnicity, suggesting that peripheral proinflammatory status such as IL-6 levels could be a useful subtyping marker for this disorder. With further research, it is hoped that our findings will be translated into personalized medicine.

Methylomic profiles reveal sex-specific differences in leukocyte composition associated with post-traumatic stress disorder.

Post-traumatic stress disorder (PTSD) is a debilitating mental disorder precipitated by trauma exposure. However, only some persons exposed to trauma develop PTSD. There are sex differences in risk; twice as many women as men develop a lifetime diagnosis of PTSD. Methylomic profiles derived from peripheral blood are well-suited for investigating PTSD because DNA methylation (DNAm) encodes individual response to trauma and may play a key role in the immune dysregulation characteristic of PTSD pathophysiology. In the current study, we leveraged recent methodological advances to investigate sex-specific differences in DNAm-based leukocyte composition that are associated with lifetime PTSD. We estimated leukocyte composition on a combined methylation array dataset (483 participants, ∼450 k CpG sites) consisting of two civilian cohorts, the Detroit Neighborhood Health Study and Grady Trauma Project. Sex-stratified Mann-Whitney U test and two-way ANCOVA revealed that lifetime PTSD was associated with significantly higher monocyte proportions in males, but not in females (Holm-adjusted p-val < 0.05). No difference in monocyte proportions was observed between current and remitted PTSD cases in males, suggesting that this sex-specific difference may reflect a long-standing trait of lifetime history of PTSD, rather than current state of PTSD. Associations with lifetime PTSD or PTSD status were not observed in any other leukocyte subtype and our finding in monocytes was confirmed using cell estimates based on a different deconvolution algorithm, suggesting that our sex-specific findings are robust across cell estimation approaches. Overall, our main finding of elevated monocyte proportions in males, but not in females with lifetime history of PTSD provides evidence for a sex-specific difference in peripheral blood leukocyte composition that is detectable in methylomic profiles and that may reflect long-standing changes associated with PTSD diagnosis.

Inflammation and post-traumatic stress disorder.

While post-traumatic stress disorder (PTSD) is currently diagnosed based solely on classic psychological and behavioral symptoms, a growing body of evidence has highlighted a link between this disorder and alterations in the immune and inflammatory systems. Epidemiological studies have demonstrated that PTSD is associated with significantly increased rates of physical comorbidities in which immune dysregulation is involved, such as metabolic syndrome, atherosclerotic cardiovascular disease, and autoimmune diseases. In line with this, a number of blood biomarker studies have reported that compared to healthy controls, individuals with PTSD exhibit significantly elevated levels of proinflammatory markers, such as interleukin-1ß, interleukin-6, tumor necrosis factor-α, and C-reactive protein. Moreover, various lines of animal and human research have suggested that inflammation is not only associated with PTSD but also can play an important role in its pathogenesis and pathophysiology. In this review, we first summarize evidence suggestive of increased inflammation in PTSD. We then examine findings that suggest possible mechanisms of inflammation in this disorder in terms of two different but interrelated perspectives: putative causes of increased proinflammatory activities and potential consequences that inflammation generates. Given that there is currently a dearth of treatment options for PTSD, possibilities of new therapeutic approaches using pharmacological and non-pharmacological treatments/interventions that have anti-inflammatory effects are also discussed. Despite the increasing attention given to the inflammatory pathology of PTSD, there remains much to be elucidated, including more detailed mechanisms of inflammation, potential usefulness of inflammatory biomarkers as diagnostic and prognostic markers, and efficacy of novel treatment strategies targeting inflammation.

The ethanolic extract of Aralia continentalis ameliorates cognitive deficits via modifications of BDNF expression and anti-inflammatory effects in a rat model of post-traumatic stress disorder.

BACKGROUND: Post-traumatic stress disorder (PTSD) is a disease associated with that the experience of traumatic stress. The traumatic experience results in the development of a prolonged stress response that causes impaired memory function and increased inflammation in the hippocampus. Currently, antidepressants are the only approved therapy for PTSD. However, the efficacy of antidepressants in the treatment of PTSD is marginal. The ethanol extract of Aralia continentalis (AC) is traditionally used in oriental medicine, and has been showed to possess pharmacological properties, including anti-inflammatory, anti-cancer, anti-atherosclerotic, and anti-diabetic effects. Nevertheless, the effects of AC on cognitive memory and its mechanism of action in PTSD remain unclear. Given the necessity of further treatment options for PTSD, we investigated the effect of AC on the spatial cognitive impairment caused by single prolonged stress (SPS) in a rat model of PTSD. METHODS: Male rats were treated with various intraperitoneal (i.p.) doses of AC for 21 consecutive days after inducing chronic stress with the SPS procedure. RESULTS: Cognitive impairment caused by SPS were inhibited after treatment with 100 mg/kg AC, as measured by the Morris water maze test and an object recognition test. Additionally, AC treatment significantly alleviated memory-related decreases in brain-derived neurotrophic factor (BDNF) mRNA and protein levels in the hippocampus. Our results suggest that AC significantly inhibited the cognitive deficits caused by SPS via increased expression of pro-inflammatory cytokines, including tumor necrosis factor-α and interleukin-6, in the rat brain. CONCLUSIONS: AC reversed the behavioral impairments and inflammation triggered by SPS-derived traumatic stress and should be further evaluated as a potential therapeutic drug for PTSD.

Inflammation as a predictor of disease course in posttraumatic stress disorder and depression: A prospective analysis from the Mind Your Heart Study.

BACKGROUND: Prior research has focused largely on the pro-inflammatory states of PTSD and depression, with few studies evaluating the direction of inflammation's association with these disorders. To clarify whether inflammation plays a role in the development of PTSD or depression, we assessed the predictive value of inflammatory biomarkers on the courses of these conditions in a cohort of Veterans. METHODS: This research was part of the Mind Your Heart Study, a prospective cohort study designed to examine PTSD-related health outcomes. Between 2008 and 2010, 746 San Francisco area Veterans Administration patients were enrolled. At baseline, inflammatory biomarkers were measured from fasting morning venous blood draws, and cortisol and catecholamine levels were measured from 24-hour urine samples. PTSD was diagnosed using the PTSD Checklist at baseline and annual follow-up. Depression was evaluated using the 9-item Patient Health Questionnaire at baseline and follow-up. Ordinal logistic regression models were used to assess the predictive value of baseline biomarker levels on clinically relevant courses of PTSD and depression categorized and ordered as none, resolved, developed, and chronic. RESULTS: After adjustment for age and sex, elevated levels of white blood cell count (OR = 1.27(1.10-1.47), p = 0.001), C-reactive protein (OR = 1.20(1.04-1.39), p = 0.02), fibrinogen (OR = 1.19(1.03-1.38), p = 0.02), and ESR (OR = 1.17(1.00-1.36, p = 0.05), and decreased levels of urine cortisol (OR = 0.84(0.71-0.99), p = 0.04) were significant predictors of poorer courses of PTSD. Elevated levels of WBC count (OR = 1.31(1.14-1.50), p < 0.001), CRP (OR = 1.24(1.07-1.43), p = 0.003), fibrinogen (OR = 1.26(1.09-1.46), p = 0.002), and catecholamines (OR = 1.17(1.01-1.36), p = 0.04) were significant predictors of poorer courses of depression. After additionally controlling for physical activity, elevated WBC count (p = 0.002) and decreased levels of urine cortisol (p = 0.05) remained significant predictors of PTSD course, and elevated WBC count (p = 0.001), CRP (p = 0.03), and fibrinogen (p = 0.02) remained significant predictors of depression course. After adjusting for all significant variables, elevated WBC count (p = 0.02) was a significant predictor of a poorer course of PTSD, and elevated WBC count (p = 0.04) and platelet count (p = 0.03) were significant predictors of a poorer course of depression. CONCLUSIONS: Increased levels of several inflammatory biomarkers were associated with significantly increased odds of clinically worse courses of PTSD and depression. Inflammation may be a target for prevention and treatment of these mental health disorders.

Old Friends, immunoregulation, and stress resilience.

There is a considerable body of evidence indicating that chronic adverse experience, especially chronic psychosocial stress/trauma, represents a major risk factor for the development of many somatic and affective disorders, including inflammatory bowel disease (IBD) and posttraumatic stress disorder (PTSD). However, the mechanisms underlying the development of chronic stress-associated disorders are still in large part unknown, and current treatment and prevention strategies lack efficacy and reliability. A greater understanding of mechanisms involved in the development and persistence of chronic stress-induced disorders may lead to novel approaches to prevention and treatment of these disorders. In this review, we provide evidence indicating that increases in immune (re-)activity and inflammation, potentially promoted by a reduced exposure to immunoregulatory microorganisms ("Old Friends") in today's modern society, may be causal factors in mediating the vulnerability to development and persistence of stress-related pathologies. Moreover, we discuss strategies to increase immunoregulatory processes and attenuate inflammation, as for instance contact with immunoregulatory Old Friends, which appears to be a promising strategy to promote stress resilience and to prevent/treat chronic stress-related disorders.

Posttraumatic stress disorder is associated with enhanced interleukin-6 response to mental stress in subjects with a recent myocardial infarction.

BACKGROUND: Posttraumatic Stress Disorder (PTSD) is prevalent among patients who survived an acute coronary syndrome, and is associated with adverse outcomes, but the mechanisms underlying these associations are unclear. Individuals with PTSD have enhanced sensitivity of the noradrenergic system to stress which may lead to immune activation. We hypothesized that survivors of a myocardial infarction (MI) who have PTSD would show an enhanced inflammatory response to acute psychological stress compared to those without PTSD. METHODS: Individuals with a verified history of MI within 8 months and a clinical diagnosis of current PTSD underwent a mental stress speech task. Inflammatory biomarkers including interleukin-6 (IL-6), high-sensitivity C reactive protein (HsCRP), matrix metallopeptidase 9 (MMP-9), intercellular adhesion molecule (ICAM)-1, vascular cell adhesion molecule (VCAM)-1 and monocyte chemoattractant protein (MCP)-1 were measured at rest and 90 min after mental stress. RESULTS: Among 271 patients in the study (mean age 51 ±â€¯7 years, 50% female, 60% African-American), the prevalence of PTSD was 12%. Mental stress resulted in a significant increase in IL-6, but the increase was more marked in patients with PTSD (126% increase) than those without (63% increase) (p = 0.001). MCP-1 showed a modest increase with stress which was similar in patients with PTSD (9% increase) and without PTSD (6% increase) (p = 0.35). CRP did not increase with stress in either group. CONCLUSION: MI patients with current PTSD exhibit enhanced IL-6 response to psychosocial stress, suggesting a mechanistic link between PTSD and adverse cardiovascular outcomes as well as other diseases associated with inflammation.