Serum Biomarkers of a Pro-Neuroinflammatory State May Define the Pre-Operative Risk for Postoperative Delirium in Spine Surgery.

Advances in spine surgery enable technically safe interventions in older patients with disabling spine disease, yet postoperative delirium (POD) poses a serious risk for postoperative recovery. This study investigates biomarkers of pro-neuroinflammatory states that may help objectively define the pre-operative risk for POD. This study enrolled patients aged ≥60 scheduled for elective spine surgery under general anesthesia. Biomarkers for a pro-neuroinflammatory state included S100 calcium-binding protein ß (S100ß), brain-derived neurotrophic factor (BDNF), Gasdermin D, and the soluble ectodomain of the triggering receptor expressed on myeloid cells 2 (sTREM2). Postoperative changes of Interleukin-6 (IL-6), Interleukin-1ß (IL-1ß), and C-reactive protein (CRP) were assessed as markers of systemic inflammation preoperatively, intraoperatively, and early postoperatively (up to 48 h). Patients with POD (n = 19, 75.7 ± 5.8 years) had higher pre-operative levels of sTREM2 (128.2 ± 69.4 pg/mL vs. 97.2 ± 52.0 pg/mL, p = 0.049) and Gasdermin D (2.9 ± 1.6 pg/mL vs. 2.1 ± 1.4 pg/mL, p = 0.29) than those without POD (n = 25, 75.6 ± 5.1 years). STREM2 was additionally a predictor for POD (OR = 1.01/(pg/mL) [1.00-1.03], p = 0.05), moderated by IL-6 (Wald-χ2 = 4.06, p = 0.04). Patients with POD additionally showed a significant increase in IL-6, IL-1ß, and S100ß levels on the first postoperative day. This study identified higher levels of sTREM2 and Gasdermin D as potential markers of a pro-neuroinflammatory state that predisposes to the development of POD. Future studies should confirm these results in a larger cohort and determine their potential as an objective biomarker to inform delirium prevention strategies.

Duration of Surgery and Intraoperative Blood Pressure Management Are Modifiable Risk Factors for Postoperative Neurocognitive Disorders After Spine Surgery: Results of the Prospective CONFESS Study.

STUDY DESIGN: Prospective quasi-experimental observational study. OBJECTIVE: The objective of this study was to evaluate whether duration of surgery is a modifiable risk factor for postoperative delirium (POD) after spine surgery and explore further modifiable risk factors. In addition, we sought to investigate the association between POD and postoperative cognitive dysfunction and persistent neurocognitive disorders. SUMMARY OF BACKGROUND DATA: Advances in spine surgery enable technically safe interventions in elderly patients with disabling spine disease. The occurrence of POD and delayed neurocognitive complications ( e.g. postoperative cognitive dysfunction/persistent neurocognitive disorder) remain a concern since these contribute to inferior functional outcomes and long-term care dependency after spine surgery. MATERIALS AND METHODS: This prospective single-center study recruited patients aged 60 years or above and scheduled for elective spine surgery between February 2018 and March 2020. Functional (Barthel Index, BI) and cognitive outcomes [Consortium to Establish a Registry for Alzheimer's Disease (CERAD) test battery; telephone Montréal Cognitive Assessment] were assessed at baseline, three (V3), and 12 months postoperatively. The primary hypothesis was that the duration of surgery predicts POD. Multivariable predictive models of POD included surgical and anesthesiological parameters. RESULTS: Twenty-two percent of patients developed POD (n=22/99). In a multivariable model, duration of surgery [OR adj =1.61/h (95% CI, 1.20-2.30)], age [OR adj =1.22/yr (95% CI, 1.10-1.36)], and baseline deviations of intraoperative systolic blood pressure [25th percentile: OR adj =0.94/mm Hg (95% CI, 0.89-0.99); 90th percentile: OR adj =1.07/mm Hg (95% CI, 1.01-1.14)] were significantly associated with POD. Postoperative cognitive scores generally improved (V3, ΔCERAD total z -score: 0.22±0.63). However, this positive group effect was counteracted by POD [beta: -0.87 (95% CI, -1.31 to 0.42)], older age [beta: -0.03/yr (95% CI, -0.05 to 0.01)], and lack of functional improvement [ΔBI; beta: -0.04/point (95% CI, -0.06 to 0.02)]. Cognitive scores at twelve months remained inferior in the POD group, adjusted for baseline cognition/age. CONCLUSIONS: This study identified distinct neurocognitive effects after spine surgery, which are influenced by perioperative risk factors. Potential cognitive benefits are counteracted by POD, rendering its prevention critical in an aging population.

Gastrointestinal Hormones in Healthy Adults: Reliability of Repeated Assessments and Interrelations with Eating Habits and Physical Activity.

Background: Gastrointestinal hormones (GIHs) are crucial for the regulation of a variety of physiological functions and have been linked to hunger, satiety, and appetite control. Thus, they might constitute meaningful biomarkers in longitudinal and interventional studies on eating behavior and body weight control. However, little is known about the physiological levels of GIHs, their intra-individual stability over time, and their interaction with other metabolic and lifestyle-related parameters. Therefore, the aim of this pilot study is to investigate the intra-individual stability of GIHs in normal-weight adults over time. Methods: Plasma concentrations of ghrelin, leptin, GLP-1 (glucagon-like-peptide), and PP (pancreatic polypeptide) were assessed by enzyme-linked immunosorbent assay (ELISA) in 17 normal-weight, healthy adults in a longitudinal design at baseline and at follow-up six months later. The reliability of the measurements was estimated using intra-class correlation (ICC). In a second step, we considered the stability of GIH levels after controlling for changes in blood glucose and hemoglobin A1 (HbA1c) as well as self-reported physical activity and dietary habits. Results: We found excellent reliability for ghrelin, good reliability for GLP1 and PP, and moderate reliability for leptin. After considering glucose, HbA1c, physical activity, and dietary habits as co-variates, the reliability of ghrelin, GLP1, and PP did not change significantly; the reliability of leptin changed to poor reliability. Conclusions: The GIHs ghrelin, GLP1, and PP demonstrated good to excellent test-retest reliability in healthy individuals, a finding that was not modified after adjusting for glucose control, physical activity, or dietary habits. Leptin showed only moderate to poor reliability, which might be linked to weight fluctuations, albeit small, between baseline and follow-up assessment in our study sample. Together, these findings support that ghrelin, GLP1, and PP might be further examined as biomarkers in studies on weight control, with GLP1 and PP serving as anorexic markers and ghrelin as an orexigenic marker. Additional reliability studies in obese individuals are necessary to verify or refute our findings for this cohort.

Central Nervous System-Infiltrating T Lymphocytes in Stroke Are Activated via Their TCR (T-Cell Receptor) but Lack CD25 Expression.

Background and Purpose: T lymphocytes contribute to secondary brain damage after stroke. It has not been fully investigated whether this contribution is caused by antigen-specific or antigen-nonspecific activation of T lymphocytes. Lymphocytes from Nur77GFP transgenic mice express a fluorescent protein upon activation via the TCR (T-cell receptor), allowing the differentiation of activation mode in a natural repertoire of immune cells and antigens. Methods: Middle cerebral artery occlusion or sham surgery was performed, and T-lymphocyte activation was analyzed by flow cytometry in the brain, spleen, and blood 16 hours, 2 days, 3 days, 4 days, and 7 days after surgery. Results: Ipsilateral hemispheric T-lymphocyte invasion peaked on day 4 poststroke. Here, we observed PD-1 (programmed cell death protein 1) expression on almost all invading T lymphocytes, while CD25 expression was low. CD25+, CD69+, or PD-1+ T lymphocytes predominantly displayed antigen-specific activation; the opposite was observed for T lymphocytes isolated from the blood. A mixed activation that favored antigen-specific activation was observed in the spleen. PD-1 was upregulated within the brain, whereas CD25 was not. Antigen-specific T lymphocytes home to the brain, while antigen-nonspecifically activated cells remain within the blood. Conclusions: Our data clearly demonstrate antigen-specific activation of T lymphocytes infiltrating ischemic brain lesions in stroke. The high expression of inhibitory PD-1 and low expression of CD25 on activated T lymphocytes in the brain most likely reflect immunosuppressive mechanisms.

The neuroendocrine effects of dehydroepiandrosterone and 17ß-estradiol in the in vitro preterm hyperoxia infant model.

Preterm birth causes neurological deficits. Previously, we demonstrated that fetal zone steroids reduce hyperoxia-mediated cell death in vitro. In immature oligodendrocytes (OLN-93 cells), dehydroepiandrosterone + 17ß-estradiol co-treatment had synergistic beneficial effects while signals were transduced through different receptors. In immature astrocytes (C6 cells), both hormones compete for the same receptor and no synergistic effects were observed. 17ß-estradiol and progesterone drastically decrease while fetal zone steroids, mainly dehydroepiandrosterone, remain persistently high within preterm infants until term. Substitution of 17ß-estradiol and progesterone does not improve neurological outcomes. We investigated the influence of dehydroepiandrosterone, 17ß-estradiol or dehydroepiandrosterone + 17ß-estradiol treatment in C6 or OLN-93 cells on steroid receptor availability and activation of intracellular signaling molecules in hyperoxic cell culture. We sought explanations of the observed synergistic effect in preliminary study. In C6 cells, the generated signaling of dehydroepiandrosterone + 17ß-estradiol treatment has no synergistic effects. The combined effect on this particular pathway does not potentiate cell survival. In OLN-93 cells, we observed significant differences in the early generated signaling of 17ß-estradiol + dehydroepiandrosterone treatment to either 17ß-estradiol dehydroepiandrosterone alone but never to both at the same time. The latter finding needs, therefore, further investigation to explain synergistic effects. Nevertheless, we add insight into the receptor and signaling cascade alterations induced by 17ß-estradiol, dehydroepiandrosterone or 17ß-estradiol + dehydroepiandrosterone treatment of C6 and OLN-93 cells in hyperoxia.

Correction: Evaluating Mechanisms of Postoperative Delirium and Cognitive Dysfunction Following Elective Spine Surgery in Elderly Patients (CONFESS): Protocol for a Prospective Observational Trial.

[This corrects the article DOI: 10.2196/15488.].

Evaluating Mechanisms of Postoperative Delirium and Cognitive Dysfunction Following Elective Spine Surgery in Elderly Patients (CONFESS): Protocol for a Prospective Observational Trial.

BACKGROUND: Elderly people are at particular high risk for postoperative delirium (POD) following spine surgery, which is associated with longer hospital stays, higher costs, risk for delayed complications, long-term care dependency, and cognitive dysfunction (POCD). It is insufficiently understood which mechanisms and risk factors contribute to the development of POD and POCD following these major but plannable surgeries. OBJECTIVE: This study aims to identify modifiable risk factors in spine surgery. A better understanding thereof would help adapt medical management and surgical strategies to individual risk profiles. METHODS: This is a single-center observational study jointly conducted by the departments of neurosurgery, neurology, and anesthesiology at a tertiary care hospital in Germany. All patients aged 60 years and older presenting to the neurosurgery outpatient clinic or ward for elective spine surgery are screened for eligibility. Exclusion criteria include presence of neurodegenerative or history of psychiatric disease and medication with significant central nervous system activity (eg, antidepressants, antipsychotics, sedatives). Surgical and anesthetic procedures including duration of surgery as primary end point of this study are thoroughly documented. All patients are furthermore evaluated for their preoperative cognitive abilities by a number of tests, including the Consortium to Establish a Registry for Alzheimer's Disease Plus test battery. Physical, mental, and social health and well-being are assessed using the Patient-Reported Outcome Measurement Information System Profile 29 and Hospital Anxiety and Depression Scale. Patients additionally receive preoperative cerebrovascular ultrasound and structural and functional brain imaging. The immediate postoperative period includes screening for POD using the Nursing Delirium Screening Scale and validation through Diagnostic and Statistical Manual of Mental Disorders, 5th Edition, criteria. We furthermore investigate markers of (neuro)inflammation (eg, interleukins, C-reactive protein, tumor necrosis factor alpha). Preoperative examinations are repeated 3 months postoperatively to investigate the presence of POCD and its mechanisms. Statistical analyses will compare delirious and nondelirious patients for predictors of immediate (POD) and delayed (POCD) cognitive dysfunction. RESULTS: This is the first study to prospectively evaluate risk factors for POD and POCD in spine surgery. Recruitment is ongoing, and data collection is estimated to be finished with the inclusion of 200 patients by mid-2020. CONCLUSIONS: The identification of mechanisms, possibly common, underlying POD and POCD would be a major step toward defining effective interventional strategies early in or even before the postoperative period, including the adaptation of surgical strategies to individual risk profiles. TRIAL REGISTRATION: ClinicalTrials.gov NCT03486288; https://clinicaltrials.gov/ct2/show/NCT03486288. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/15488.

Protective Effects of Fetal Zone Steroids Are Comparable to Estradiol in Hyperoxia-Induced Cell Death of Immature Glia.

Impaired neurodevelopment in preterm infants is caused by prematurity itself; however, hypoxia/ischemia, inflammation, and hyperoxia contribute to the extent of impairment. Because preterm birth is accompanied by a dramatic decrease in 17ß-estradiol (E2) and progesterone, preliminary clinical studies have been carried out to substitute these steroids in preterm infants; however, they failed to confirm significantly improved neurologic outcomes. We therefore hypothesized that the persistently high postnatal production of fetal zone steroids [mainly dehydroepiandrosterone (DHEA)] until term could interfere with E2-mediated protection. We investigated whether E2 could reduce hyperoxia-mediated apoptosis in three immature glial cell types and detected the involved receptors. Thereafter, we investigated protection by the fetal zone steroids DHEA, 16α-hydroxy-DHEA, and androstenediol. For DHEA, the involved receptors were evaluated. We examined aromatases, which convert fetal zone steroids into more estrogenic compounds. Finally, cotreatment was compared against single hormone treatment to investigate synergism. In all cell types, E2 and fetal zone steroids resulted in significant dose-dependent protection, whereas the mediating receptors differed. The neuroprotection by fetal zone steroids highly depended on the cell type-specific expression of aromatases, the receptor repertoire, and the potency of the fetal zone steroids toward these receptors. No synergism in fetal zone steroid and E2 cotreatment was detected in two of three cell types. Therefore, E2 supplementation may not be beneficial with respect to neuroprotection because fetal zone steroids circulate in persistently high concentrations until term in preterm infants. Hence, a refined experimental model for preterm infants is required to investigate potential treatments.

Reduced Numbers and Impaired Function of Regulatory T Cells in Peripheral Blood of Ischemic Stroke Patients.

BACKGROUND AND PURPOSE: Regulatory T cells (Tregs) have been suggested to modulate stroke-induced immune responses. However, analyses of Tregs in patients and in experimental stroke have yielded contradictory findings. We performed the current study to assess the regulation and function of Tregs in peripheral blood of stroke patients. Age dependent expression of CD39 on Tregs was quantified in mice and men. METHODS: Total FoxP3(+) Tregs and CD39(+)FoxP3(+) Tregs were quantified by flow cytometry in controls and stroke patients on admission and on days 1, 3, 5, and 7 thereafter. Treg function was assessed by quantifying the inhibition of activation-induced expression of CD69 and CD154 on T effector cells (Teffs). RESULTS: Total Tregs accounted for 5.0% of CD4(+) T cells in controls and <2.8% in stroke patients on admission. They remained below control values until day 7. CD39(+) Tregs were most strongly reduced in stroke patients. On day 3 the Treg-mediated inhibition of CD154 upregulation on CD4(+) Teff was impaired in stroke patients. CD39 expression on Treg increased with age in peripheral blood of mice and men. CONCLUSION: We demonstrate a loss of active FoxP3(+)CD39(+) Tregs from stroke patient's peripheral blood. The suppressive Treg function of remaining Tregs is impaired after stroke.

Disrupted Mer receptor tyrosine kinase expression leads to enhanced MZ B-cell responses.

Control of lymphocyte homeostasis is essential to ensure efficient immune responses and to prevent autoimmunity. Splenic marginal zone B cells are important producers of autoantibodies, and are subject to stringent tolerance mechanisms to prevent autoimmunity. In this paper, we explore the role of the Mer tyrosine kinase (Mertk) in regulating autoreactive B cells. This receptor tyrosine kinase serves to bind apoptotic cells, to mediate their phagocytosis, and to regulate subsequent cytokine production. Mice lacking Mertk suffer from impaired apoptotic cell clearance and develop a lupus-like autoimmune syndrome. Here we show that such Mertk-KO mice have expanded numbers of splenic marginal zone B cells. Mertk-KO mice bearing a DNA-specific immunoglobulin heavy-chain transgene (3H9) produced anti-DNA antibodies that appeared to be secreted largely by marginal zone B cells. Finally, Mertk-KO mice developed greater antibody responses after NP-Ficoll immunization than their B6 counterparts. Taken together, our data show that Mertk has a major effect on the development of the marginal zone B-cell compartment. Mertk is also important in establishing DNA-specific B-cell tolerance in 3H9 anti-DNA transgenic mice.

Glatiramer acetate-specific human CD8(+) T cells: increased IL-4 production in multiple sclerosis is reduced by glatiramer acetate treatment.

Glatiramer acetate (GA) is an approved drug for therapy of relapsing remitting MS that acts as a T cell antigen. Here, we report the cloning of HLA restricted, GA-specific human CD8(+) T cells. In addition, we analyzed the cytokine profile of GA-reactive CD8(+) T cell lines. Unexpectedly, IL-4 was increased in untreated MS patients as compared to healthy individuals (p<0.001). In GA-treated patients, however, IL-4 (p<0.001), IL-10 (p<0.001) and TNF-alpha (p<0.001) were decreased. Thus, while GA is known to induce a TH2 bias in CD4(+) T cells, we detected a distinct pattern in GA-reactive CD8(+) T cells.