Pediatric Traumatic Brain Injury: An Update on Preclinical Models, Clinical Biomarkers, and the Implications of Cerebrovascular Dysfunction

Landscape of gut mucosal immune cells showed gap of follicular or memory B cells into plasma cells in immunological non-responders

BACKGROUND

The gut is an important site for human immunodeficiency virus (HIV) infection and immune responses. The role of gut mucosal immune cells in immune restoration in patients infected with HIV undergoing antiretroviral therapy remains unclear.

METHODS

Ileocytes, including 54 475 immune cells, were obtained from colonoscopic biopsies of five HIV-negative controls, nine immunological responders (IRs), and three immunological non-responders (INRs) and were analyzed using single-cell RNA sequencing. Immunohistochemical assays were performed for validation. The 16S rRNA gene was amplified using PCR in faecal samples to analyze faecal microbiota. Flow cytometry was used to analyze CD4+ T-cell counts and the activation of T cells.

RESULTS

This study presents a global transcriptomic profile of the gut mucosal immune cells in patients infected with HIV. Compared with the IRs, the INRs exhibited a lower proportion of gut plasma cells, especially the IGKC+IgA+ plasma cell subpopulation. IGKC+IgA+ plasma cells were negatively associated with enriched f. Prevotellaceae the INRs and negatively correlated with the overactivation of T cells, but they were positively correlated with CD4+ T-cell counts. The INRs exhibited a higher proportion of B cells than the IRs. Follicular and memory B cells were significantly higher in the INRs. Reduced potential was observed in the differentiation of follicular or memory B cells into gut plasma cells in INRs. In addition, the receptor-ligand pairs CD74_MIF and CD74_COPA of memory B/ follicular helper T cells were significantly reduced in the INRs, which may hinder the differentiation of memory and follicular B cells into plasma cells.

CONCLUSIONS

Our study shows that plasma cells are dysregulated in INRs and provides an extensive resource for deciphering the immune pathogenesis of HIV in INRs.

KEY POINTS

An investigation was carried out at the single-cell-level to analyze gut mucosal immune cells alterations in PLWH after ART. B cells were significantly increased and plasma cells were significantly decreased in the INRs compared to the IRs and NCs. There are gaps in the transition from gut follicular or memory B cellsinto plasma cells in INRs.

Applying the National Institute on Minority Health and Health Disparities Research Framework to Social Determinants of Health in the Context of Sport-Related Concussion: A Clinical Commentary

Sport-related concussion (SRC) is a prevalent injury. Significant disparities in SRC outcomes exist across racial and ethnic groups. These disparities may be attributed to the unequal distribution of political power (or influence) and resource allocation in various communities, shaping individuals' social determinants of health (SDOH). However, the influence of SDOH on SRC outcomes remains understudied. In this clinical commentary, we use the National Institute on Minority Health and Health Disparities Research Framework and describe how its application can help address gaps in our understanding of SDOH and SRC. This framework provides a comprehensive approach to investigating and addressing health disparities by considering SDOH along multiple levels and domains of influence. Using this framework, athletic trainers can identify areas requiring intervention and better understand how SDOH influence SRC outcomes. This understanding can help athletic trainers develop tailored interventions to promote equitable care for patients with SRC.

Anti-Inflammatory and Cortical Responses after Transcranial Direct Current Stimulation in Disorders of Consciousness: An Exploratory Study

Disorders of consciousness (DoC) due to severe traumatic brain injury (TBI) are associated with severe disability and an alteration of cortical activation, angiogenesis, and inflammation, which are crucial elements for behavioural recovery. This exploratory study aimed to evaluate anti-inflammatory and cortical responses after transcranial direct current stimulation (tDCS) in traumatic prolonged disorders of consciousness. Ten minimally conscious state (MCS) patients underwent ten sessions of anodal tDCS (five sessions/week, two weeks, 40 min/session) on the primary motor cortex bilaterally. Clinical evaluations were performed using the Coma Recovery Scale-Revised (CRS-R) pre- and post-treatment. In contrast, after single and multiple tDCS sessions, the haemodynamic cortical response was obtained with functional near-infrared spectroscopy (fNIRS). Moreover, angiogenesis (angiopoietin-2, BMP9, endoglin, HbEFG, HGF, IL8, Leptin, PLGF, VEGF-A, and VEGF-C) and inflammation (GM-CSF, IFNg, IP10, MCP1, and TNFα) circulating biomarkers were collected. A significant haemodynamic response was observed after a single tDCS session, with an increased activation from 4.4 (3.1-6.1) to 7.6 (2.9-15.7) a.u. (p = 0.035). After ten tDCS sessions, a significant reduction of angiopoietin-2, VEGF-C, and IP-10 was detected. Moreover, a correlation between behavioural (CRS-R), TNFα (r = 0.89; p = 0.007), and IP10 (r = 0.81; p = 0.014) variation was found. In conclusion, a single tDCS session can increase the cortical activation in MCS patients. Moreover, multiple tDCS sessions showed an anti-inflammatory effect related to behavioural improvement.

Acute stress modulates the outcome of traumatic brain injury-associated gene expression and behavioral responses

Psychological stress and traumatic brain injury (TBI) result in long-lasting emotional and behavioral impairments in patients. So far, the interaction of psychological stress with TBI not only in the brain but also in peripheral organs is poorly understood. Herein, the impact of acute stress (AS) occurring immediately before TBI is investigated. For this, a mouse model of restraint stress and TBI was employed, and their influence on behavior and gene expression in brain regions, the hypothalamic-pituitary-adrenal (HPA) axis, and peripheral organs was analyzed. Results demonstrate that, compared to single AS or TBI exposure, mice treated with AS prior to TBI showed sex-specific alterations in body weight, memory function, and locomotion. The induction of immediate early genes (IEGs, e.g., c-Fos) by TBI was modulated by previous AS in several brain regions. Furthermore, IEG upregulation along the HPA axis (e.g., pituitary, adrenal glands) and other peripheral organs (e.g., heart) was modulated by AS-TBI interaction. Proteomics of plasma samples revealed proteins potentially mediating this interaction. Finally, the deletion of Atf3 diminished the TBI-induced induction of IEGs in peripheral organs but left them largely unaltered in the brain. In summary, AS immediately before brain injury affects the brain and, to a strong degree, also responses in peripheral organs.

Do astrocytes act as immune cells after pediatric TBI?

Astrocytes are in contact with the vasculature, neurons, oligodendrocytes and microglia, forming a local network with various functions critical for brain homeostasis. One of the primary responders to brain injury are astrocytes as they detect neuronal and vascular damage, change their phenotype with morphological, proteomic and transcriptomic transformations for an adaptive response. The role of astrocytic responses in brain dysfunction is not fully elucidated in adult, and even less described in the developing brain. Children are vulnerable to traumatic brain injury (TBI), which represents a leading cause of death and disability in the pediatric population. Pediatric brain trauma, even with mild severity, can lead to long-term health complications, such as cognitive impairments, emotional disorders and social dysfunction later in life. To date, the underlying pathophysiology is still not fully understood. In this review, we focus on the astrocytic response in pediatric TBI and propose a potential immune role of the astrocyte in response to trauma. We discuss the contribution of astrocytes in the local inflammatory cascades and secretion of various immunomodulatory factors involved in the recruitment of local microglial cells and peripheral immune cells through cerebral blood vessels. Taken together, we propose that early changes in the astrocytic phenotype can alter normal development of the brain, with long-term consequences on neurological outcomes, as described in preclinical models and patients.

Nutritional Support Following Traumatic Brain Injury: A Comprehensive Review

Traumatic brain injury (TBI) can contribute to extensive dysbiosis of the gastrointestinal system, leading to worsened outcomes. The importance of nutrition in recovery is underappreciated but highly important. In this focused review, we discuss the timing of nutritional interventions with supporting data. We highlight routes of administration that are important given the extent of injury often seen in TBI. The increased energy demands can be met through these approaches. Furthermore, patients need increased vitamins, minerals, and supplements. These interventions are constantly being refined. The current standards are reviewed with an emphasis on evidence-based practices.

Comprehensive Assessment of Mid-Regional Proadrenomedullin, Procalcitonin, Neuron-Specific Enolase and Protein S100 for Predicting Pediatric Severe Trauma Outcomes

The development of multiple organ failure and septic complications increases the cumulative risk of mortality in children with severe injury. Clinically available biochemical markers have shown promise in assessing the severity and predicting the development of complications and outcomes in such cases. This study aimed to determine informative criteria for assessing the severity and outcome prediction of severe injury in children based on levels of mid-regional proadrenomedullin (MR-proADM) procalcitonin (PCT), neuron-specific enolase (NSE), and protein S100. Biomarker levels were measured in 52 children with severe injury (ISS ≥ 16) on the 1st, 3rd, 7th, and 14th days after admission to the ICU. The children were divided into groups based on their favorable (n = 44) or unfavorable (n = 8) outcomes according to the Severe Injury Outcome Scale, as well as their favorable (n = 35) or unfavorable (n = 15) outcomes according to the Glasgow Coma Outcome Scale (GOS). The study also evaluated the significance of biomarker levels in predicting septic complications (with SC (n = 16) and without SC (n = 36)) and diagnosing and stratifying multiple organ failure (with MOF (n = 8) and without MOF (n = 44)). A comprehensive assessment of MR-proADM and PCT provided the highest diagnostic and prognostic efficacy for early diagnosis, risk stratification of multiple organ failure, and outcome prediction in severe injury cases involving children. Additionally, the inclusion of the S100 protein in the study allowed for further assessment of brain damage in cases of traumatic brain injury (TBI), contributing to the overall prognostic model.

Potential Biomarkers in Experimental Animal Models for Traumatic Brain Injury

Traumatic brain injury (TBI) is a complex and multifaceted disorder that has become a significant public health concern worldwide due to its contribution to mortality and morbidity. This condition encompasses a spectrum of injuries, including axonal damage, contusions, edema, and hemorrhage. Unfortunately, specific effective therapeutic interventions to improve patient outcomes following TBI are currently lacking. Various experimental animal models have been developed to mimic TBI and evaluate potential therapeutic agents to address this issue. These models are designed to recapitulate different biomarkers and mechanisms involved in TBI. However, due to the heterogeneous nature of clinical TBI, no single experimental animal model can effectively mimic all aspects of human TBI. Accurate emulation of clinical TBI mechanisms is also tricky due to ethical considerations. Therefore, the continued study of TBI mechanisms and biomarkers, of the duration and severity of brain injury, treatment strategies, and animal model optimization is necessary. This review focuses on the pathophysiology of TBI, available experimental TBI animal models, and the range of biomarkers and detection methods for TBI. Overall, this review highlights the need for further research to improve patient outcomes and reduce the global burden of TBI.

Multimodal Neuromonitoring and Neurocritical Care in Swine to Enhance Translational Relevance in Brain Trauma Research

Neurocritical care significantly impacts outcomes after moderate-to-severe acquired brain injury, but it is rarely applied in preclinical studies. We created a comprehensive neurointensive care unit (neuroICU) for use in swine to account for the influence of neurocritical care, collect clinically relevant monitoring data, and create a paradigm that is capable of validating therapeutics/diagnostics in the unique neurocritical care space. Our multidisciplinary team of neuroscientists, neurointensivists, and veterinarians adapted/optimized the clinical neuroICU (e.g., multimodal neuromonitoring) and critical care pathways (e.g., managing cerebral perfusion pressure with sedation, ventilation, and hypertonic saline) for use in swine. Moreover, this neurocritical care paradigm enabled the first demonstration of an extended preclinical study period for moderate-to-severe traumatic brain injury with coma beyond 8 h. There are many similarities with humans that make swine an ideal model species for brain injury studies, including a large brain mass, gyrencephalic cortex, high white matter volume, and topography of basal cisterns, amongst other critical factors. Here we describe the neurocritical care techniques we developed and the medical management of swine following subarachnoid hemorrhage and traumatic brain injury with coma. Incorporating neurocritical care in swine studies will reduce the translational gap for therapeutics and diagnostics specifically tailored for moderate-to-severe acquired brain injury.

Investigation of clinical findings and CT scan in children with minor head trauma

BACKGROUND

The most common cause of death or severe impairment in children older than one-year-old is traumatic brain injury (TBI). Assessing TBI in children with minor head trauma (MHT) using clinical findings from history-taking and a physical exam is crucial to minimizing unnecessary brain CTs and more accurately predicting TBI. We aimed to evaluate the findings of brain CT scans in children with mild head trauma and their relationship with clinical signs and symptoms to avoid unnecessary interventions in many children with MHT.

METHODS

This cross-sectional-analytical study was performed to evaluate the findings of brain CT scans in children with MHT and their relationship with clinical signs and symptoms that were referred to Poursina Hospital in Rasht in the first half of 2021. Children were divided into two age groups: under two years and 2-12 years, and analyzed separately. Initially, a list containing all demographic information, patients' clinical signs, and symptoms were prepared. The collected data were then analyzed using SPSS software version 26.

RESULTS

According to the results, the mean age of patients was 66.01 months and 88 were boys (56.4%). The most common mechanism of injury was falling from a height. Most patients had isolated head injuries. Among the accompanying injuries, facial injuries were the most common. Among the clinical factors studied, cranial fracture on CT scan and GCS less than 15 were significantly associated with the occurrence of traumatic brain injury on CT scan. In addition, cranial fracture on CT scan, injury severity, and history of vomiting had the highest positive predictive value, respectively.

CONCLUSION

Standard history and clinical examination are sufficient to identify high-risk cases of pediatric head injuries. GCS is the most important risk factor for pediatric MHT. Requesting a CT scan is not recommended without these risk factors.