Systemic inflammation induces apoptosis with variable vulnerability of different brain regions

Risk factors associated with cognitive impairment in patients after pediatric liver transplantation

Data on cognitive function after pLT are rare, particularly regarding children with cognitive impairment. From 2016 to 2018, we evaluated cognitive function in 36 patients after pLT aged 6-17 years with the WISC IV (at least 1 year after transplantation) and analyzed potential risk factors for cognitive impairment (IQ < 70) by means of retrospective medical data (peri-, intra-, and post-operative factors, and donor and specific organ data of the primary liver transplant) on an exploratory base. At a median age of 9.6 years (range = 6-16.9), 22% of patients were cognitive impaired (IQ < 70; including five untestable patients with severe cognitive impairment). Children tested with the WISC IV scored within the lower normal range but differed significantly from normal population. Strongest associations showed infections at pLT, development of severe sepsis requiring intensive care within the first 6 months after pLT, neurological complications within the first 10 days and the occurrence of CPR during or after pLT, and as early laboratory variables pH value on day 0 after pLT. In our analysis, neither intraoperative factors nor donor-specific factors seemed to influence cognitive outcome. In our small cohort, medical complications before and after pLT but not transplantation itself had an influence on cognitive outcome. As such, children experiencing medical problems before and in the early post-operative phase after pLT should be closely evaluated in larger samples regarding their neurological and psychomotor development during vulnerable phases and should receive early educational support to improve long-term cognitive function.

mTOR inhibition as a possible pharmacological target in the management of systemic inflammatory response and associated neuroinflammation by lipopolysaccharide challenge in rats

Neuroinflammation plays a critical role during sepsis triggered by microglial activation. Mammalian target of rapamycin (mTOR) has gained attraction in neuroinflammation, however, the mechanism remains unclear. Our goal was to assess the effects of mTOR inhibition by rapamycin on inflammation, microglial activation, oxidative stress, and apoptosis associated with the changes in the inhibitor-κB (IκB)-α/nuclear factor-κB (NF-κB)/hypoxia-inducible factor-1α (HIF-1α) pathway activity following a systemic challenge with lipopolysaccharide (LPS). Rats received saline (10 mL/kg), LPS (10 mg/kg), and (or) rapamycin (1 mg/kg) intraperitoneally. Inhibition of mTOR by rapamycin blocked phosphorylated form of ribosomal protein S6, NF-κB p65 activity by increasing degradation of IκB-α in parallel with HIF-1α expression increased by LPS in the kidney, heart, lung, and brain tissues. Rapamycin attenuated the increment in the expression of tumor necrosis factor-α and interleukin-1β, the inducible nitric oxide synthase, gp91^phox, and p47^phox in addition to nitrite levels elicited by LPS in tissues or sera. Concomitantly, rapamycin treatment reduced microglial activation, brain expression of caspase-3, and Bcl-2-associated X protein while it increased expression of B cell lymphoma 2 induced by LPS. Overall, this study supports the hypothesis that mTOR contributes to the detrimental effect of LPS-induced systemic inflammatory response associated with neuroinflammation via IκB-α/NF-κB/HIF-1α signaling pathway.

Aging and Microglial Response following Systemic Stimulation with Escherichia coli in Mice

Systemic infection is an important risk factor for the development cognitive impairment and neurodegeneration in older people. Animal experiments show that systemic challenges with live bacteria cause a neuro-inflammatory response, but the effect of age on this response in these models is unknown. Young (2 months) and middle-aged mice (13-14 months) were intraperitoneally challenged with live Escherichia coli (E. coli) or saline. The mice were sacrificed at 2, 3 and 7 days after inoculation; for all time points, the mice were treated with ceftriaxone (an antimicrobial drug) at 12 and 24 h after inoculation. Microglial response was monitored by immunohistochemical staining with an ionized calcium-binding adaptor molecule 1 (Iba-1) antibody and flow cytometry, and inflammatory response by mRNA expression of pro- and anti-inflammatory mediators. We observed an increased microglial cell number and moderate morphologically activated microglial cells in middle-aged mice, as compared to young mice, after intraperitoneal challenge with live E. coli. Flow cytometry of microglial cells showed higher CD45 and CD11b expressions in middle-aged infected mice compared to young infected mice. The brain expression levels of pro-inflammatory genes were higher in middle-aged than in young infected mice, while middle-aged infected mice had similar expression levels of these genes in the systemic compartment. We conclude that systemic challenge with live bacteria causes an age-dependent neuro-inflammatory and microglial response. Our data show signs of an age-dependent disconnection of the inflammatory transcriptional signature between the brain and the systemic compartment.

Sepsis-Associated Encephalopathy: from Pathophysiology to Progress in Experimental Studies

Sepsis is an organ dysfunction caused by an uncontrolled inflammatory response from the host to an infection. Sepsis is the main cause of morbidity and mortality in intensive care units (ICU) worldwide. One of the first organs to suffer from injuries resulting from sepsis is the brain. The central nervous system (CNS) is particularly vulnerable to damage, mediated by inflammatory and oxidative processes, which can cause the sepsis-associated encephalopathy (SAE), being reported in up to 70% of septic patients. This review aims to bring a summary of the main pathophysiological changes and dysfunctions in SAE, and the main focuses of current experimental studies for new treatments and therapies. The pathophysiology of SAE is complex and multifactorial, combining intertwined processes, and is promoted by countless alterations and dysfunctions resulting from sepsis, such as inflammation, neuroinflammation, oxidative stress, reduced brain metabolism, and injuries to the integrity of the blood-brain barrier (BBB). The treatment is limited once its cause is not completely understood. The patient's sedation is far to provide an adequate treatment to this complex condition. Studies and experimental advances are important for a better understanding of its pathophysiology and for the development of new treatments, medicines, and therapies for the treatment of SAE and to reduce its effects during and after sepsis.

The Synaptic Dysregulation in Adolescent Rats Exposed to Maternal Immune Activation

Maternal immune activation (MIA) is a risk factor for neurodevelopmental disorders in offspring, but the pathomechanism is largely unknown. The aim of our study was to analyse the molecular mechanisms contributing to synaptic alterations in hippocampi of adolescent rats exposed prenatally to MIA. MIA was evoked in pregnant female rats by i.p. administration of lipopolysaccharide at gestation day 9.5. Hippocampi of offspring (52-53-days-old rats) were analysed using transmission electron microscopy (TEM), qPCR and Western blotting. Moreover, mitochondrial membrane potential, activity of respiratory complexes, and changes in glutathione system were measured. It was found that MIA induced changes in hippocampi morphology, especially in the ultrastructure of synapses, including synaptic mitochondria, which were accompanied by impairment of mitochondrial electron transport chain and decreased mitochondrial membrane potential. These phenomena were in agreement with increased generation of reactive oxygen species, which was evidenced by a decreased reduced/oxidised glutathione ratio and an increased level of dichlorofluorescein (DCF) oxidation. Activation of cyclin-dependent kinase 5, and phosphorylation of glycogen synthase kinase 3β on Ser9 occurred, leading to its inhibition and, accordingly, to hypophosphorylation of microtubule associated protein tau (MAPT). Abnormal phosphorylation and dysfunction of MAPT, the manager of the neuronal cytoskeleton, harmonised with changes in synaptic proteins. In conclusion, this is the first study demonstrating widespread synaptic changes in hippocampi of adolescent offspring prenatally exposed to MIA.

Effect of atorvastatin on delirium status of patients in the intensive care unit: a randomized controlled trial

INTRODUCTION

Delirium is one of the most prevalent complications in intensive care unit (ICU) patients, which is related to worse clinical outcomes including a longer ICU stay, longer duration of mechanical ventilation, higher mortality rates and increased risk of cognitive impairment. Observational studies have suggested that statins might have a positive effect on delirium status of hospitalized patients. To date, there has been no trial assessing the effect of atorvastatin on delirium status in critically ill patients. Thus, the aim of the current study was to determine the efficacy of atorvastatin on delirium status of patients in the ICU.

METHODS

In this randomized, double-blind and controlled trial, a total of 90 patients in the general ICU who had delirium for at least 2 days were randomly divided into atorvastatin (40 mg/day) (n = 40) and control (n = 50) groups. Delirium status of the patients was determined twice a day at 10:00 a.m. and 18:00 p.m. using the Richmond Agitation-Sedation Scale (RASS).

RESULTS

Administration 40 mg/day of atorvastatin significantly reduced the mean RASS score and increased delirium-free days at both morning and afternoon time points compared to the control group (p < 0.05).

CONCLUSIONS

Administration of atorvastatin had a significant positive effect on delirium status in patients admitted to the ICU.

Isoflurane reduces septic neuron injury by HO‑1‑mediated abatement of inflammation and apoptosis

Sepsis-associated encephalopathy (SAE) frequently occurs in critically ill patients with severe systemic infections. Subanesthetic isoflurane (0.7% ISO) possesses anti-inflammatory, antioxidant and anti-apoptotic properties against a number of human diseases, including brain injury. The activation of heme oxygenase-1 (HO-1) impedes inflammation, oxidation and apoptosis, thus alleviating sepsis-induced brain damage. However, whether 0.7% ISO affords protection against septic neuronal injury involving HO-1 activation is unclear. The present study aimed to investigate the neuroprotective effects of 0.7% ISO and its potential underlying mechanisms in SAE using a mouse model established by cecal ligation and puncture (CLP). The results indicated that the expression and activity of HO-1 in the mouse hippocampus were increased by CLP, and further enhanced by ISO. ISO reduced the death rate, brain water content and blood-brain barrier disruption, but improved the learning and memory functions of CLP-treated mice. ISO significantly decreased the production of pro-inflammatory cytokines and the levels of oxidative indictors in the serum and hippocampus, as well as the number of apoptotic neurons and the expression of pro-apoptotic proteins in the hippocampus. Inversely, anti-inflammatory factors, antioxidative enzymes and anti-apoptotic proteins were markedly increased by ISO administration. However, the neuroprotective effects of ISO were abolished by a HO-1 inhibitor. Overall, these findings suggested that 0.7% ISO alleviated SAE via its anti-inflammatory, antioxidative and anti-apoptotic properties, which involved the activated form of HO-1.

Experimental lung injury induces cerebral cytokine mRNA production in pigs

Background

Acute respiratory distress syndrome (ARDS) is an important disease with a high incidence among patients admitted to intensive care units. Over the last decades, the survival of critically ill patients has improved; however, cognitive deficits are among the long-term sequelae. We hypothesize that acute lung injury leads to upregulation of cerebral cytokine synthesis.

Methods

After approval of the institutional and animal care committee, 20 male pigs were randomized to one of three groups: (1) Lung injury by oleic acid injection (OAI), (2) ventilation only (CTR) or (3) untreated. We compared neuronal numbers, proportion of neurons with markers for apoptosis, activation state of Iba-1 stained microglia cells and cerebral mRNA levels of different cytokines between the groups 18 hours after onset of lung injury.

Results

We found an increase in hippocampal TNFalpha (p < 0.05) and IL-6 (p < 0.05) messenger RNA (mRNA) in the OAI compared to untreated group as well as higher hippocampal IL-6 mRNA compared to control (p < 0.05). IL-8 and IL-1beta mRNA showed no differences between the groups. We found histologic markers for beginning apoptosis in OAI compared to untreated (p < 0.05) and more active microglia cells in OAI and CTR compared to untreated (p < 0.001 each).

Conclusion

Hippocampal cytokine transcription increases within 18 hours after the induction of acute lung injury with histological evidence of neuronal damage. It remains to be elucidated if increased cytokine mRNA synthesis plays a role in the cognitive decline observed in survivors of ARDS.

Acute Systemic Inflammatory Response Alters Transcription Profile of Genes Related to Immune Response and Ca2+ Homeostasis in Hippocampus; Relevance to Neurodegenerative Disorders

Acute systemic inflammatory response (SIR) triggers an alteration in the transcription of brain genes related to neuroinflammation, oxidative stress and cells death. These changes are also characteristic for Alzheimer’s disease (AD) neuropathology. Our aim was to evaluate gene expression patterns in the mouse hippocampus (MH) by using microarray technology 12 and 96 h after SIR evoked by lipopolysaccharide (LPS). The results were compared with microarray analysis of human postmortem hippocampal AD tissues. It was found that 12 h after LPS administration the expression of 231 genes in MH was significantly altered (FC > 2.0); however, after 96 h only the S100a8 gene encoding calgranulin A was activated (FC = 2.9). Gene ontology enrichment analysis demonstrated the alteration of gene expression related mostly to the immune-response including the gene Lcn2 for Lipocalin 2 (FC = 237.8), involved in glia neurotoxicity. The expression of genes coding proteins involved in epigenetic regulation, histone deacetylases (Hdac4,5,8,9,11) and bromo- and extraterminal domain protein Brd3 were downregulated; however, Brd2 was found to be upregulated. Remarkably, the significant increase in expression of Lcn2, S100a8, S100a9 and also Saa3 and Ch25h, was found in AD brains suggesting that early changes of immune-response genes evoked by mild SIR could be crucial in AD pathogenesis.

Aging influences in the blood-brain barrier permeability and cerebral oxidative stress in sepsis

Sepsis is a set of serious manifestations throughout the body produced by an infection, leading to changes that compromise cellular homeostasis and can result in dysfunction of the central nervous system. The elderly have a higher risk of developing sepsis than younger peoples. Under the influence of inflammatory mediators and oxidizing agents released in the periphery as a result of the infectious stimulus, changes occur in the blood-brain barrier (BBB) permeability, with neutrophil infiltration, the passage of toxic compounds, activation of microglia and production of reactive species that results in potentiation of neuroimmune response, with the progression of neuronal damage and neuroinflammation. The objective of this study is to compare BBB permeability and the development of oxidative stress in the hippocampus and prefrontal cortex of young and old rats submitted to polymicrobial sepsis induction. Male Wistar rats grouped into sham (60d), sham (210d), cecal ligation and perforation (CLP) (60d) and CLP (210d) with n = 16 per experimental group were evaluated using the CLP technique to induce sepsis. The brain regions were collected at 24 h after sepsis induction to determine BBB permeability, myeloperoxidase (MPO) activity as marker of neutrophil activation, nitrite/nitrate (N/N) levels as marker of reactive nitrogen species, thiobarbituric acid reactive substances as marker of lipid peroxidation, protein carbonylation as marker of protein oxidation, and activity of antioxidant enzyme catalase (CAT). There was an increase in the BBB permeability in the CLP groups, and this was enhanced with aging in both brain region. MPO activity in the brain regions increased in the CLP groups, along with a hippocampal increase in the CLP 210d group compared to the 60d group. The concentration of N/N in the brain region was increased in the CLP groups. The damage to lipids and proteins in the two structures was enhanced in the CLP groups, while only lipid peroxidation was higher in the prefrontal cortex of the CLP 210d group compared to the 60d. CAT activity in the hippocampus was decreased in both CLP groups, and this was also influenced by age, whereas in the prefrontal cortex there was only a decrease in CAT in the CLP 60d group compared to the sham 60d. These findings indicate that aging potentiated BBB permeability in sepsis, which possibly triggered an increase in neutrophil infiltration and, consequently, an increase in oxidative stress.

S100A9 Upregulation Contributes to Learning and Memory Impairments by Promoting Microglia M1 Polarization in Sepsis Survivor Mice

Sepsis-associated encephalopathy (SAE) is a clinical syndrome of brain dysfunction secondary to sepsis, which is characterized by long-term neurocognitive deficits such as memory, attention, and executive dysfunction. However, the mechanisms underlying SAE remain unclear. By using transcriptome sequencing approach, we showed that hippocampal S100A9 was significantly increased in sepsis induced by cecal ligation and puncture (CLP) or lipopolysaccharide (LPS) challenge. Thus, we used S100A9 inhibitor Paquinimod to study the role of S100A9 in cognitive impairments in CLP-induced and LPS-induced mice models of SAE. Sepsis survivor mice underwent behavioral tests or the hippocampal tissues subjected to Western blotting, real-time quantitative PCR, and immunohistochemistry. Our results showed that CLP-induced and LPS-induced memory impairments were accompanied with increased expressions of hippocampal microglia Iba1 and CD86 (M1 markers), but reduced expression of Arg1 (M2 marker). Notably, S100A9 inhibition significantly improved the survival rate and learning and memory impairments in sepsis survivors, with a shift from M1 to M2 phenotype. Taken together, our study suggests that S100A9 upregulation might contribute to learning and memory impairments by promoting microglia M1 polarization in sepsis survivors, whereas S100A9 inhibition might provide a potential therapeutic target for SAE.

Endoplasmic reticulum stress regulates cell injury in lipopolysaccharide-induced nerve cells

OBJECTIVE

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis, and excessive endoplasmic reticulum (ER) stress is closely correlated with the cell injury caused by sepsis. This study aimed to analyze the possible role of ER stress in SAE cell models.

METHODS

PC12 and MES23.5 cells were treated with increasing concentrations of lipopolysaccharides (LPS). The Cell Counting Kit-8 assay was used to detect cell viability and terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining was performed to assess cell apoptosis. In addition, the protein expression levels of ER stress markers [GRP78, CHOP, inositol-requiring enzyme 1 (IRE1), and PKR-like ER kinase (PERK)] and apoptosis-related proteins (Bax, Bcl-2, caspase-3, and cleaved caspase-3) were analyzed using western blotting.

RESULTS

LPS treatment activated ER stress markers in both the PC12 and MES23.5 cells. The overexpression of GRP78 significantly reduced cell viability and enhanced cell apoptosis in a time-dependent manner. An ER stress inhibitor, 4-PBA, significantly enhanced cell viability and inhibited the cell apoptosis induced by LPS. Therefore, an enhanced unfolded protein response (UPR) and UPR suppression may regulate cell apoptosis.

CONCLUSIONS

UPR was shown to be involved in regulating LPS-induced neuron injury. UPR could be a potential therapeutic target in SAE.

Inflammation Induced by Natural Neuronal Death and LPS Regulates Neural Progenitor Cell Proliferation in the Healthy Adult Brain

Inflammation is typically considered a negative response to injury or insult; however, recent advances demonstrate that inflammatory cells regulate development, plasticity, and homeostasis through anticytotoxic, progenerative responses. Here, we extend analyses of neuroinflammation to natural neurodegenerative and homeostatic states by exploiting seasonal plasticity in cytoarchitecture of the avian telencephalic song control nucleus, high vocal center [HVC (proper name)], in the songbird Gambel's white-crowned sparrow (Zonotrichia leucophrys gambelii). We report that local injection of the endotoxin lipopolysaccharide into HVC of birds in both breeding (high circulating testosterone level) and nonbreeding (low circulating testosterone level) conditions increased neural progenitor cell proliferation in the nearby but distinct ventricular zone. Additionally, we found that oral administration of the anti-inflammatory drug minocycline during seasonal regression of HVC reduced microglia activation in HVC and prevented the normal proliferative response in the ventricular zone to apoptosis in HVC. Our results suggest that local neuroinflammation positively regulates neural progenitor cell proliferation and, in turn, contributes to the previously described repatterning of HVC cytoarchitecture following seasonally induced neuronal loss.

Metformin Attenuates Brain Injury by Inhibiting Inflammation and Regulating Tight Junction Proteins in Septic Rats

OBJECTIVE

Metformin has a potent inhibitory activity against inflammation and oxidative stress, which inevitably occur in sepsis-associated encephalopathy (SAE). The precise mechanisms underlying neuroprotective effects of metformin in SAE, are still unclear. In the present work, the protective effect of metformin on SAE using cecal ligation and puncture (CLP) model of sepsis, was assessed.

MATERIALS AND METHODS

In this experimental study, CLP procedure was performed in Wistar rats and 50 mg/kg metformin was administered immediately. Specific markers of sepsis severity, inflammation, blood brain barrier (BBB) dysfunction, and brain injury, were investigated. Specific assay kits and real-time polymerase chain reaction (RT-PCR) were used. Histopathological assessment was also carried out.

RESULTS

Treatment with metformin decreased murine sepsis score (MSS), lactate, platelet lymphocyte ratio (PLR), and high mobility group box (HMGB1) levels. The expression levels of claudin 3 (Cldn3) and claudin 5 (Cldn5) were increased following treatment with metformin. Metformin decreased the expression of S100b, neuron specific enolase (Nse), and glial fibrillary acidic protein (Gfap).

CONCLUSION

Our study suggests that metformin may inhibit inflammation and increase tight junction protein expressions which may improve BBB function and attenuate CLP-induced brain injury. Hence, the potential beneficial effects of metformin in sepsis, should be considered in future.

Simvastatin Prevents Long-Term Cognitive Deficits in Sepsis Survivor Rats by Reducing Neuroinflammation and Neurodegeneration

Sepsis-associated encephalopathy causes brain dysfunction that can result in cognitive impairments in sepsis survivor patients. In previous work, we showed that simvastatin attenuated oxidative stress in brain structures related to memory in septic rats. However, there is still a need to evaluate the long-term impact of simvastatin administration on brain neurodegenerative processes and cognitive damage in sepsis survivors. Here, we investigated the possible neuroprotective role of simvastatin in neuroinflammation, and neurodegeneration conditions of brain structures related to memory in rats at 10 days after sepsis survival. Male Wistar rats (250-300 g) were submitted to cecal ligation and puncture (CLP, n = 42) or remained as non-manipulated (naïve, n = 30). Both groups were treated (before and after the surgery) by gavage with simvastatin (20 mg/kg) or an equivalent volume of saline and observed for 10 days. Simvastatin-treated rats that survived to sepsis showed a reduction in the levels of nitrate, IL1-β, and IL-6 and an increase in Bcl-2 protein expression in the prefrontal cortex and hippocampus, and synaptophysin only in the hippocampus. Immunofluorescence revealed a reduction of glial activation, neurodegeneration, apoptosis, and amyloid aggregates confirmed by quantification of GFAP, Iba-1, phospho Ser₃₉₆-tau, total tau, cleaved caspase-3, and thioflavin-S in the prefrontal cortex and hippocampus. In addition, treated animals presented better performance in tasks involving habituation memory, discriminative, and aversive memory. These results suggest that statins exert a neuroprotective role by upregulation of the Bcl-2 and gliosis reduction, which may prevent the cognitive deficit observed in sepsis survivor animals.

Vancomycin Is Protective in a Neonatal Mouse Model of Staphylococcus epidermidis-Potentiated Hypoxic-Ischemic Brain Injury

Infection is correlated with increased risk of neurodevelopmental sequelae in preterm infants. In modeling neonatal brain injury, Toll-like receptor agonists have often been used to mimic infections and induce inflammation. Using the most common cause of bacteremia in preterm infants, Staphylococcus epidermidis, we present a more clinically relevant neonatal mouse model that addresses the combined effects of bacterial infection together with subsequent hypoxic-ischemic brain insult. Currently, there is no neuroprotective treatment for the preterm population. Hence, we tested the neuroprotective effects of vancomycin with and without adjunct therapy using the anti-inflammatory agent pentoxifylline. We characterized the effects of S. epidermidis infection on the inflammatory response in the periphery and the brain, as well as the physiological changes in the central nervous system that might affect neurodevelopmental outcomes. Intraperitoneal injection of postnatal day 4 mice with a live clinical isolate of S. epidermidis led to bacteremia and induction of proinflammatory cytokines in the blood, as well as transient elevations of neutrophil and monocyte chemotactic cytokines and caspase 3 activity in the brain. When hypoxia-ischemia was induced postinfection, more severe brain damage was observed in infected animals than in saline-injected controls. This infection-induced inflammation and potentiated brain injury was inoculum dose dependent and was alleviated by the antibiotic vancomycin. Pentoxifylline did not provide any additional neuroprotective effect. Thus, we show for the first time that live S. epidermidis potentiates hypoxic-ischemic preterm brain injury and that peripheral inhibition of inflammation with antibiotics, such as vancomycin, reduces the extent of brain injury.

Demarcation of Sepsis-Induced Peripheral and Central Acidosis with pH (Low) Insertion Cycle Peptide

Acidosis is a key driver for many diseases, including cancer, sepsis, and stroke. The spatiotemporal dynamics of dysregulated pH across disease remain elusive, and current diagnostic strategies do not provide localization of pH alterations. We sought to explore if PET imaging using hydrophobic cyclic peptides that partition into the cellular membrane at low extracellular pH (denoted as pH [low] insertion cycles, or pHLIC) can permit accurate in vivo visualization of acidosis. Methods: Acid-sensitive cyclic peptide c[E₄W₅C] pHLIC was conjugated to bifunctional maleimide-NO2A and radiolabeled with ⁶⁴Cu (half-life, 12.7 h). C57BL/6J mice were administered lipopolysaccharide (15 mg/kg) or saline (vehicle) and serially imaged with [⁶⁴Cu]Cu-c[E₄W₅C] over 24 h. Ex vivo autoradiography was performed on resected brain slices and subsequently stained with cresyl violet to enable high-resolution spatial analysis of tracer accumulation. A non-pH-sensitive cell-penetrating control peptide (c[R₄W₅C]) was used to confirm specificity of [⁶⁴Cu]Cu-c[E₄W₅C]. CD11b (macrophage/microglia) and TMEM119 (microglia) immunostaining was performed to correlate extent of neuroinflammation with [⁶⁴Cu]Cu-c[E₄W₅C] PET signal. Results: [⁶⁴Cu]Cu-c[E₄W₅C] radiochemical yield and purity were more than 95% and more than 99%, respectively, with molar activity of more than 0.925 MBq/nmol. Significantly increased [⁶⁴Cu]Cu-c[E₄W₅C] uptake was observed in lipopolysaccharide-treated mice (vs. vehicle) within peripheral tissues, including blood, lungs, liver, and small intestines (P < 0.001-0.05). Additionally, there was significantly increased [⁶⁴Cu]Cu-c[E₄W₅C] uptake in the brains of lipopolysaccharide-treated animals. Autoradiography confirmed increased uptake in the cerebellum, cortex, hippocampus, striatum, and hypothalamus of lipopolysaccharide-treated mice (vs. vehicle). Immunohistochemical analysis revealed microglial or macrophage infiltration, suggesting activation in brain regions containing increased tracer uptake. [⁶⁴Cu]Cu-c[R₄W₅C] demonstrated significantly reduced uptake in the brain and periphery of lipopolysaccharide mice compared with the acid-mediated [⁶⁴Cu]Cu-c[E₄W₅C] tracer. Conclusion: Here, we demonstrate that a pH-sensitive PET tracer specifically detects acidosis in regions associated with sepsis-driven proinflammatory responses. This study suggests that [⁶⁴Cu]Cu-pHLIC is a valuable tool to noninvasively assess acidosis associated with both central and peripheral innate immune activation.

Vasopressor Therapy and the Brain: Dark Side of the Moon

Sepsis, a leading cause of morbidity and mortality, is caused by a deregulated host response to pathogens, and subsequent life-threatening organ dysfunctions. All major systems, including the cardiovascular, respiratory, renal, hepatic, hematological, and the neurological system may be affected by sepsis. Sepsis associated neurological dysfunction is triggered by multiple factors including neuro-inflammation, excitotoxicity, and ischemia. Ischemia results from reduced cerebral blood flow, caused by extreme variations of blood pressure, occlusion of cerebral vessels, or more subtle defects of the microcirculation. International guidelines comprehensively describe the initial hemodynamic management of sepsis, revolving around the normalization of systemic hemodynamics and of arterial lactate. By contrast, the management of sepsis patients suffering from brain dysfunction is poorly detailed, the only salient point being mentioned is that sedation and analgesia should be optimized. However, sepsis and the hemodynamic consequences thereof as well as vasopressors may have severe untoward neurological consequences. The current review describes the general neurological complications, as well as the consequences of vasopressor therapy on the brain and its circulation and addresses methods for cerebral monitoring during sepsis.

Postseptic Cognitive Impairment and Expression of APOE in Peripheral Blood: The Cognition After SepsiS (CASS) Observational Pilot Study

BACKGROUND

Cognitive impairment after sepsis is an important clinical problem. Determinants of postseptic cognitive impairment are not well understood. We thus undertook a systems biology approach to exploring a possible role for apolipoprotein E (APOE) in postseptic cognitive impairment.

DESIGN

Prospective, observational cohort.

SETTING

Intermountain Medical Center, a tertiary referral center in Utah.

PATIENTS/PARTICIPANTS

Patients with sepsis admitted to study intensive care units.

INTERVENTIONS

None.

METHODS

We obtained peripheral blood for deep sequencing of RNA and followed up survivors at 6 months with a battery of cognitive instruments. We defined cognitive impairment based on the 6-month Hayling test of executive function. In our primary analysis, we employed weighted network analysis. Secondarily, we compared variation in gene expression between patients with normal versus impaired cognition.

MEASUREMENTS AND MAIN RESULTS

We enrolled 40 patients, of whom 34 were follow-up eligible and 31 (91%) completed follow-up; 1 patient's RNA sample was degraded-the final analytic cohort was 30 patients. Mean Hayling test score was 5.8 (standard deviation 1.1), which represented 20% with impaired executive function. The network module containing APOE was dominated by low-expression genes, with no association on primary analysis (P = .8). Secondary analyses suggested several potential lines of future investigation, including oxidative stress.

CONCLUSIONS

In this prospective pilot cohort, executive dysfunction affected 1 in 5 survivors of sepsis. The APOE gene was sparsely transcribed in peripheral leukocytes and not associated with cognitive impairment. Future lines of research are suggested.

Agomelatine could prevent brain and cerebellum injury against LPS-induced neuroinflammation in rats

Sepsis, systemic hyper-inflammatory immune response, causes the increase of morbidity and mortality rates due to multi-organ diseases such as neurotoxicity. Lipopolysaccharide (LPS) induces inflammation, oxidative stress and apoptosis to cause brain damage. We aimed to evaluate the antioxidant, anti-inflammatory and antiapoptotic effects of Agomelatine (AGM) on LPS induced brain damage via NF-kB signaling. Twenty-four animals were divided into three groups as control, LPS (5 mg/kg) and LPS + AGM (20 mg/kg). Six hours after the all administrations, rats were sacrificed, brain tissues were collected for biochemical, histopathological and immunohistochemical analysis. In LPS group; total oxidant status (TOS), OSI index, Caspase-8 (Cas-8), NF-kß levels increased and Total antioxidant status (TAS) levels decreased biochemically and Cas-8, haptoglobin and IL-10 expressions increased and sirtuin-1 (SIRT-1) levels decreased immunohistochemically. AGM treatment reversed these parameters except haptoglobin levels in hippocampus and SIRT-1 levels in cerebellum. Besides, AGM treatment blocked the phosphorylation of NF-kB biochemically and ameliorated increased the levels of hyperemia, edema and degenerative changes histopathologically. In conclusion, AGM enhanced SIRT-1 levels to negatively regulate the transcription and activation of p-NF-kB/p65 which caused to ameliorate inflammation, oxidative stress and apoptosis.

Kaolin-induced hydrocephalus causes acetylcholinesterase activity dysfunction following hypothalamic damage in infant rats

In hydrocephalus, the progressive accumulation of cerebrospinal fluid (CSF) causes dilatation of the lateral ventricles affecting the third ventricle and diencephalic structures such as the hypothalamus. These structures play a key role in the regulation of several neurovegetative functions by the production of the hormones. Since endocrine disturbances are commonly observed in hydrocephalic children, we investigated the impact of progressive ventricular dilation on the hypothalamus of infant rats submitted to kaolin-induced hydrocephalus. Seven-day-old infant rats were submitted to hydrocephalus induction by kaolin 20% injection method. After 14 days, the animals were decapitated and brain was collected to analyze mitochondrial function, neuronal activity by acetylcholinesterase (AChE) enzyme, oxidative damage, glial activation, and, neurotransmission-related proteins and anti-apoptotic processes in the hypothalamus. The hydrocephalic animals showed reduction in respiratory rates in the States of phosphorylation (P < 0.01) and non-phosphorylation (P < 0.05); increase in AChE activity in both the cytosol (P < 0.05) and the membrane (P < 0.01); decrease in synaptophysin (P < 0.05) and Bcl-2 (P < 0.05) contents and; increase in protein carbonyl (P < 0.01), GFAP (P < 0.01) and Iba-1 (P < 0.05) levels. The results demonstrate that ventricular dilation causes hypothalamic damage characterized by cholinergic dysfunction and suggests further investigation of the synthesis and secretion of hormones to generate new approaches and to assist in the treatment of hydrocephalic patients with hormonal alterations.

Long-term cognitive impairment after acute respiratory distress syndrome: a review of clinical impact and pathophysiological mechanisms

Acute respiratory distress syndrome (ARDS) survivors experience a high prevalence of cognitive impairment with concomitantly impaired functional status and quality of life, often persisting months after hospital discharge. In this review, we explore the pathophysiological mechanisms underlying cognitive impairment following ARDS, the interrelations between mechanisms and risk factors, and interventions that may mitigate the risk of cognitive impairment. Risk factors for cognitive decline following ARDS include pre-existing cognitive impairment, neurological injury, delirium, mechanical ventilation, prolonged exposure to sedating medications, sepsis, systemic inflammation, and environmental factors in the intensive care unit, which can co-occur synergistically in various combinations. Detection and characterization of pre-existing cognitive impairment imparts challenges in clinical management and longitudinal outcome study enrollment. Patients with brain injury who experience ARDS constitute a distinct population with a particular combination of risk factors and pathophysiological mechanisms: considerations raised by brain injury include neurogenic pulmonary edema, differences in sympathetic activation and cholinergic transmission, effects of positive end-expiratory pressure on cerebral microcirculation and intracranial pressure, and sensitivity to vasopressor use and volume status. The blood-brain barrier represents a physiological interface at which multiple mechanisms of cognitive impairment interact, as acute blood-brain barrier weakening from mechanical ventilation and systemic inflammation can compound existing chronic blood-brain barrier dysfunction from Alzheimer’s-type pathophysiology, rendering the brain vulnerable to both amyloid-beta accumulation and cytokine-mediated hippocampal damage. Although some contributory elements, such as the presenting brain injury or pre-existing cognitive impairment, may be irreversible, interventions such as minimizing mechanical ventilation tidal volume, minimizing duration of exposure to sedating medications, maintaining hemodynamic stability, optimizing fluid balance, and implementing bundles to enhance patient care help dramatically to reduce duration of delirium and may help prevent acquisition of long-term cognitive impairment.

Neutrophil-Derived Microvesicle Induced Dysfunction of Brain Microvascular Endothelial Cells In Vitro

The blood-brain barrier (BBB), composed of brain microvascular endothelial cells (BMEC) that are tightly linked by tight junction (TJ) proteins, restricts the movement of molecules between the periphery and the central nervous system. Elevated systemic levels of neutrophils have been detected in patients with altered BBB function, but the role of neutrophils in BMEC dysfunction is unknown. Neutrophils are key players of the immune response and, when activated, produce neutrophil-derived microvesicles (NMV). NMV have been shown to impact the integrity of endothelial cells throughout the body and we hypothesize that NMV released from circulating neutrophils interact with BMEC and induce endothelial cell dysfunction. Therefore, the current study investigated the interaction of NMV with human BMEC and determined whether they altered gene expression and function in vitro. Using flow cytometry and confocal imaging, NMV were shown to be internalized by the human cerebral microvascular endothelial cell line hCMEC/D3 via a variety of energy-dependent mechanisms, including endocytosis and macropinocytosis. The internalization of NMV significantly altered the transcriptomic profile of hCMEC/D3, specifically inducing the dysregulation of genes associated with TJ, ubiquitin-mediated proteolysis and vesicular transport. Functional studies confirmed NMV significantly increased permeability and decreased the transendothelial electrical resistance (TEER) of a confluent monolayer of hCMEC/D3. These findings indicate that NMV interact with and affect gene expression of BMEC as well as impacting their integrity. We conclude that NMV may play an important role in modulating the permeability of BBB during an infection.

A single systemic inflammatory insult causes acute motor deficits and accelerates disease progression in a mouse model of human tauopathy

Introduction

Neuroinflammation, which contributes to neurodegeneration, is a consistent hallmark of dementia. Emerging evidence suggests that systemic inflammation also contributes to disease progression.

Methods

The ability of systemically administered lipopolysaccharide (LPS - 500 μg/kg) to effect acute and chronic behavioural changes in C57BL/6 and P301S tauopathy mice was assessed. Markers of pathology were assessed in the brain and spinal cord.

Results

P301S mice display regional microgliosis. Systemic LPS treatment induced exaggerated acute sickness behaviour and motor dysfunction in P301S mice compared with wild-type controls and advanced the onset and accelerated chronic decline. LPS treatment was associated with increased tau pathology 24 hours after LPS injection and spinal cord microgliosis at the end stage.

Discussion

This is the first demonstration that a single systemic inflammatory episode causes exaggerated acute functional impairments and accelerates the long-term trajectory of functional decline associated with neurodegeneration in a mouse model of human tauopathy. The findings have relevance to management of human dementias.

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P301S microgliosis is regional; activation occurs in the spinal cord but not in the cortex.

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Systemic LPS injection caused acute neurological deficits in P301S mice.

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This was associated with increased tau pathology 24 hours after LPS injection.

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This was independent of microglial priming as measured by IL-1β hyperexpression.

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LPS injection advanced the onset of chronic decline in P301S mice.

Recombinant CC16 regulates inflammation, oxidative stress, apoptosis and autophagy via the inhibition of the p38MAPK signaling pathway in the brain of neonatal rats with sepsis

Sepsis has a high in clinic neonatal mortality. Moreover, a considerable number of children's brains remain affected even after the treatment of sepsis and it often leaves sequelae. Therefore, early intervention for sepsis is of considerable significance. Recent studies have shown that Club cell protein (CC16) is closely related to the p38 mitogen-activated protein kinase (MAPK) signaling pathway, which can regulate inflammation, oxidative stress, apoptosis, and autophagy during sepsis. Thus, we analyzed the neuroprotective effect of recombinant CC16 (rCC16) in a neonatal sepsis rat model. For the first time, we found that the p38MAPK signaling pathway was activated in neonatal brain tissue of rats with sepsis, and the CC16 levels decreased significantly. Secondly, after the rCC16 interference, the occurrence of inflammation, oxidative stress and apoptosis were subsequently reversed, and autophagy was further stimulated. Finally, through further intervention using the p38MAPK signaling pathway inhibitor, SB203580, or its agonist, anisomycin, we confirmed that rCC16 reduced rat mortality and improve general conditions. Simultaneously, it had also neuroprotective effect. Its mechanism could be related to oxidative stress, inflammation, and apoptosis reduced and autophagy activated by rCC16 inhibiting the p38MAPK signaling pathway. Taken together, these findings provide insight into the pathogenesis, prevention, and treatment of sepsis via the activity of rCC16.

Systemic inflammation impairs microglial Aβ clearance through NLRP3 inflammasome

Alzheimer's disease is the most prevalent type of dementia and is caused by the deposition of extracellular amyloid‐beta and abnormal tau phosphorylation. Neuroinflammation has emerged as an additional pathological component. Microglia, representing the brain's major innate immune cells, play an important role during Alzheimer's. Once activated, microglia show changes in their morphology, characterized by a retraction of cell processes. Systemic inflammation is known to increase the risk for cognitive decline in human neurogenerative diseases including Alzheimer's. Here, we assess for the first time microglial changes upon a peripheral immune challenge in the context of aging and Alzheimer's in vivo, using 2‐photon laser scanning microscopy. Microglia were monitored at 2 and 10 days post‐challenge by lipopolysaccharide. Microglia exhibited a reduction in the number of branches and the area covered at 2 days, a phenomenon that resolved at 10 days. Systemic inflammation reduced microglial clearance of amyloid‐beta in APP/PS1 mice. NLRP3 inflammasome knockout blocked many of the observed microglial changes upon lipopolysaccharide, including alterations in microglial morphology and amyloid pathology. NLRP3 inhibition may thus represent a novel therapeutic target that may protect the brain from toxic peripheral inflammation during systemic infection.

Activation of β2-Adrenoceptor Attenuates Sepsis-Induced Hippocampus-Dependent Cognitive Impairments by Reversing Neuroinflammation and Synaptic Abnormalities

Sepsis-associated encephalopathy induces cognitive dysfunction via mechanisms that commonly involve neuroinflammation and synaptic plasticity impairment of the hippocampus. The β2-adrenoceptor (β2-AR) is a G-protein coupled receptor that regulates immune response and synaptic plasticity, whereas its dysfunction has been implicated in various neurodegenerative diseases. Thus, we hypothesized abnormal β2-AR signaling is involved in sepsis-induced cognitive impairment. In the present study, C57BL/6 mice were subjected to cecal ligation and puncture (CLP) to mimic the clinical human sepsis-associated encephalopathy. The levels of hippocampal β2-AR, proinflammatory cytokines tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), IL-6, cAMP-response element binding protein (CREB), brain derived neurotrophic factor (BDNF), post-synaptic density protein 95 (PSD95), and NMDA receptor 2 B subtypes (GluN2B) were determined at 6, 12, 24 h and 7 and 16 days after CLP. For the interventional study, mice were treated with β2-AR agonist clenbuterol in two ways: early treatment (immediately following CLP) and delayed treatment (on the 8th day following CLP). Neurobehavioral performances were assessed by open field and fear conditioning tests. Here, we found that hippocampal β2-AR expression was significantly decreased starting from 12 h and persisted until 16 days following CLP. Besides, sepsis mice also exhibited increasing neuroinflammation, down-regulated CREB/BDNF, decreasing PSD95 and GluN2B expression, and displayed hippocampus-dependent cognitive impairments. Notably, early clenbuterol treatment alleviated sepsis-induced cognitive deficits by polarizing microglia toward an anti-inflammatory phenotype, reducing proinflammatory cytokines including IL-1β, TNF-α, and up-regulating CREB/BDNF, PSD95, and GluN2B. Intriguingly, delayed clenbuterol treatment also improved cognitive impairments by normalization of hippocampal CREB/BDNF, PSD95, and GluN2B. In summary, our results support the beneficial effects of both early and delayed clenbuterol treatment, which suggests that activation of β2-AR has a translational value in sepsis-associated organ dysfunction including cognitive impairments.

Age and Sex Influence the Hippocampal Response and Recovery Following Sepsis

Although in-hospital mortality rates for sepsis have decreased, survivors often experience lasting physical and cognitive deficits. Moreover, older adults are more vulnerable to long-term complications associated with sepsis. We employed a murine model to examine the influence of age and sex on the brain’s response and recovery following sepsis. Young (~ 4 months) and old (~ 20 months) mice (C57BL/6) of both sexes underwent cecal ligation and puncture (CLP) with restraint stress. The hippocampal transcriptome was examined in age- and sex-matched controls at 1 and 4 days post-CLP. In general, immune- and stress-related genes increased, while neuronal, synaptic, and glial genes decreased 1 day after CLP-induced sepsis. However, specific age and sex differences were observed for the initial responsiveness to sepsis as well as the rate of recovery examined on day 4. Young females exhibited a muted transcriptional response relative to young males and old females. Old females exhibited a robust shift in gene transcription on day 1, and while most genes recovered, genes linked to neurogenesis and myelination continued to be downregulated by day 4. In contrast, old males exhibited a more delayed or prolonged response to sepsis, such that neuronal and synaptic genes continued to decrease while immune response genes continued to increase on day 4. These results suggest that aging is associated with delayed recovery from sepsis, which is particularly evident in males.

Targeting the Blood-Brain Barrier to Prevent Sepsis-Associated Cognitive Impairment

Sepsis is a systemic inflammatory disease resulting from an infection. This disorder affects 750 000 people annually in the United States and has a 62% rehospitalization rate. Septic symptoms range from typical flu-like symptoms (eg, headache, fever) to a multifactorial syndrome known as sepsis-associated encephalopathy (SAE). Patients with SAE exhibit an acute altered mental status and often have higher mortality and morbidity. In addition, many sepsis survivors are also burdened with long-term cognitive impairment. The mechanisms through which sepsis initiates SAE and promotes long-term cognitive impairment in septic survivors are poorly understood. Due to its unique role as an interface between the brain and the periphery, numerous studies support a regulatory role for the blood-brain barrier (BBB) in the progression of acute and chronic brain dysfunction. In this review, we discuss the current body of literature which supports the BBB as a nexus which integrates signals from the brain and the periphery in sepsis. We highlight key insights on the mechanisms that contribute to the BBB's role in sepsis which include neuroinflammation, increased barrier permeability, immune cell infiltration, mitochondrial dysfunction, and a potential barrier role for tissue non-specific alkaline phosphatase (TNAP). Finally, we address current drug treatments (eg, antimicrobials and intravenous immunoglobulins) for sepsis and their potential outcomes on brain function. A comprehensive understanding of these mechanisms may enable clinicians to target specific aspects of BBB function as a therapeutic tool to limit long-term cognitive impairment in sepsis survivors.

Astroglia in Sepsis Associated Encephalopathy

Cellular pathophysiology of sepsis associated encephalopathy (SAE) remains poorly characterised. Brain pathology in SAE, which is manifested by impaired perception, consciousness and cognition, results from multifactorial events, including high levels of systemic cytokines, microbial components and endotoxins, which all damage the brain barriers, instigate neuroinflammation and cause homeostatic failure. Astrocytes, being the principal homeostatic cells of the central nervous system contribute to the brain defence against infection. Forming multifunctional anatomical barriers, astroglial cells maintain brain-systemic interfaces and restrict the damage to the nervous tissue. Astrocytes detect, produce and integrate inflammatory signals between immune cells and cells of brain parenchyma, thus regulating brain immune response. In SAE astrocytes are present in both reactive and astrogliopathic states; balance between these states define evolution of pathology and neurological outcomes. In humans pathophysiology of SAE is complicated by frequent presence of comorbidities, as well as age-related remodelling of the brain tissue with senescence of astroglia; these confounding factors further impact upon SAE progression and neurological deficits.

Brain grey matter volume reduction and anxiety-like behavior in lipopolysaccharide-induced chronic pulmonary inflammation rats: A structural MRI study with histological validation

While there have been multiple fMRI studies into the brain functional changes after acutely stimulated peripheral infection, knowledge for the effect of chronic peripheral infection on whole brain morphology is still quite limited. The present study was designed to investigate the brain structural and emotional changes after peripheral local infection initiated chronic systemic inflammation and the relationship between circulating inflammatory markers and brain grey matter. Specifically, in-vivo T2-weighted MRI was performed on rats with lipopolysaccharide (LPS)-induced chronic pulmonary inflammation (CPI) and those without. Grey matter volume was quantified using diffeomorphic anatomical registration through exponentiated lie (DARTEL) enhanced voxel-based morphometry followed by between-group comparison. Open field experiment was conducted to test the potential anxiety-like behaviors after CPI, along with the ELISA estimated inflammatory markers were correlated to grey matter volume. Guided by image findings, we undertook a focused histological investigation with immunefluorescence and Nissl staining. A widespread decrease of grey matter volume in CPI-model rats was revealed. 8 of the 12 measured inflammatory markers presented differential neuroanatomical correlation patterns with three of the pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and CRP being the most notable. Lower grey matter volumes in some of the inflammatory markers related regions (amygdala, CA2 and cingulate cortex) were associated with more-severe anxiety-like behaviors. Furthermore, grey matter volumes in amygdala and CA3 were correlated negatively with the expressions of glial proteins (S100β and Nogo-A), while the grey matter volume in hypo-thalamus was changing positively with neural cell area. Overall, the neuroanatomical association patterns and the histopathology underpinning the MRI observations we demonstrated here would probably serve as one explanation for the cerebral and emotional deficits presented in the patients with CPI, which would furthermore yield new insights into the adverse effects the many other systemic inflammation and inflammatory autoimmune diseases would pose on brain morphology.

Lung-Specific Extracellular Superoxide Dismutase Improves Cognition of Adult Mice Exposed to Neonatal Hyperoxia

Lung and brain development is often altered in infants born preterm and exposed to excess oxygen, and this can lead to impaired lung function and neurocognitive abilities later in life. Oxygen-derived reactive oxygen species and the ensuing inflammatory response are believed to be an underlying cause of disease because over-expression of some anti-oxidant enzymes is protective in animal models. For example, neurodevelopment is preserved in mice that ubiquitously express human extracellular superoxide dismutase (EC-SOD) under control of an actin promoter. Similarly, oxygen-dependent changes in lung development are attenuated in transgenic Sftpc^EC−SOD mice that over-express EC-SOD in pulmonary alveolar epithelial type II cells. But whether anti-oxidants targeted to the lung provide protection to other organs, such as the brain is not known. Here, we use transgenic Sftpc^EC−SOD mice to investigate whether lung-specific expression of EC-SOD also preserves neurodevelopment following exposure to neonatal hyperoxia. Wild type and Sftpc^EC−SOD transgenic mice were exposed to room air or 100% oxygen between postnatal days 0–4. At 8 weeks of age, we investigated neurocognitive function as defined by novel object recognition, pathologic changes in hippocampal neurons, and microglial cell activation. Neonatal hyperoxia impaired novel object recognition memory in adult female but not male mice. Behavioral deficits were associated with microglial activation, CA1 neuron nuclear contraction, and fiber sprouting within the hilus of the dentate gyrus (DG). Over-expression of EC-SOD in the lung preserved novel object recognition and reduced the observed changes in neuronal nuclear size and myelin basic protein fiber density. It had no effect on the extent of microglial activation in the hippocampus. These findings demonstrate pulmonary expression of EC-SOD preserves short-term memory in adult female mice exposed to neonatal hyperoxia, thus suggesting anti-oxidants designed to alleviate oxygen-induced lung disease such as in preterm infants may also be neuroprotective.

The Role of Perioperative Statin Use in the Prevention of Delirium After Total Knee Replacement Under Spinal Anesthesia

BACKGROUND

The relationship between statin use and incidence of postoperative delirium (POD) is controversial. We investigated the association between perioperative statin use and occurrence of delirium after total knee arthroplasty (TKA) under spinal anesthesia.

METHODS

We retrospectively reviewed the electronic medical records of patients who underwent TKA under spinal anesthesia at a single tertiary care hospital between January 2005 and October 2017. POD incidence was recorded for patients who received statins continuously from 1 month before surgery until discharge and for patients who did not receive any statins. Univariable and multivariable logistic regression analyses were conducted to investigate an association between occurrence of POD and perioperative statin use.

RESULTS

In total, 6020 procedures were included, and 992 (16.4%) were associated with perioperative statin use. POD was confirmed for 304 (5.0%) procedures. The statin group showed a 1.7% significant lower incidence (P = .017) of POD (35/992, 3.5%) than the no statin group (1420/5,028, 5.4%). In multivariable logistic regression analysis, the POD incidence in the statin group was 34% lower than that in the no statin group (odds ratio [OR] 0.66, 95% confidence interval [CI] 0.45-0.97, P = .036]. Moreover, the POD incidence was decreased by 37% (OR 0.63, 95% CI 0.40-0.99, P = .047) and 79% (OR 0.21, 95% CI 0.05-0.88, P = .033) respectively, when atorvastatin and simvastatin were administered.

CONCLUSION

Continuous perioperative statin use may be associated with a significantly lower risk of delirium after TKA under spinal anesthesia; simvastatin was the most effective statin for POD prevention.

Preventing Postoperative Delirium After Major Noncardiac Thoracic Surgery-A Randomized Clinical Trial

OBJECTIVES

To assess the efficacy of haloperidol in reducing postoperative delirium in individuals undergoing thoracic surgery.

DESIGN

Randomized double-blind placebo-controlled trial.

SETTING

Surgical intensive care unit (ICU) of tertiary care center.

PARTICIPANTS

Individuals undergoing thoracic surgery (N=135).

INTERVENTION

Low-dose intravenous haloperidol (0.5 mg three times daily for a total of 11 doses) administered postoperatively.

MEASUREMENTS

The primary outcome was delirium incidence during hospitalization. Secondary outcomes were time to delirium, delirium duration, delirium severity, and ICU and hospital length of stay. Delirium was assessed using the Confusion Assessment Method for the ICU and delirium severity using the Delirium Rating Scale-Revised.

RESULTS

Sixty-eight participants were randomized to receive haloperidol and 67 placebo. No significant differences were observed between those receiving haloperidol and those receiving placebo in incident delirium (n=15 (22.1%) vs n=19 (28.4%); p = .43), time to delirium (p = .43), delirium duration (median 1 day, interquartile range (IQR) 1-2 days vs median 1 day, IQR 1-2 days; p = .71), delirium severity, ICU length of stay (median 2.2 days, IQR 1-3.3 days vs median 2.3 days, IQR 1-4 days; p = .29), or hospital length of stay (median 10 days, IQR 8-11.5 days vs median 10 days, IQR 8-12 days; p = .41). In the esophagectomy subgroup (n = 84), the haloperidol group was less likely to experience incident delirium (n=10 (23.8%) vs n=17 (40.5%); p = .16). There were no differences in time to delirium (p = .14), delirium duration (median 1 day, IQR 1-2 days vs median 1 day, IQR 1-2 days; p = .71), delirium severity, or hospital length of stay (median 11 days, IQR 10-12 days vs median days 11, IQR 10-15 days; p = .26). ICU length of stay was significantly shorter in the haloperidol group (median 2.8 days, IQR 1.1-3.8 days vs median 3.1 days, IQR 2.1-5.1 days; p = .03). Safety events were comparable between the groups.

CONCLUSION

Low-dose postoperative haloperidol did not reduce delirium in individuals undergoing thoracic surgery but may be efficacious in those undergoing esophagectomy. J Am Geriatr Soc 66:2289-2297, 2018.

Astrocytes: Heterogeneous and Dynamic Phenotypes in Neurodegeneration and Innate Immunity

Astrocytes are the most numerous cell type in the brain and perform several essential functions in supporting neuronal metabolism and actively participating in neural circuit and behavioral function. They also have essential roles as innate immune cells in responding to local neuropathology, and the manner in which they respond to brain injury and degeneration is the subject of increasing attention in neuroscience. Although activated astrocytes have long been thought of as a relatively homogenous population, which alter their phenotype in a relatively stereotyped way upon central nervous system injury, the last decade has revealed substantial heterogeneity in the basal state and significant heterogeneity of phenotype during reactive astrocytosis. Thus, phenotypic diversity occurs at two distinct levels: that determined by regionality and development and that determined by temporally dynamic changes to the environment of astrocytes during pathology. These inflammatory and pathological states shape the phenotype of these cells, with different consequences for destruction or recovery of the local tissue, and thus elucidating these phenotypic changes has significant therapeutic implications. In this review, we will focus on the phenotypic heterogeneity of astrocytes in health and disease and their propensity to change that phenotype upon subsequent stimuli.

Solid peripheral tumor leads to systemic inflammation, astrocyte activation and signs of behavioral despair in mice

Prevalence of depression is higher in patients with cancer than in the general population. Sustained systemic inflammation has been associated with depressive behavior and it has been reported that depressed patients commonly display alterations in their immune system. We previously showed that cancer in mice induces a systemic environment that promotes neutrophil activation and leukocytosis. We thus hypothesized that the peripheral systemic response to a solid tumor leads to endothelial activation, which may promote inflammatory changes in the brain with behavioral consequences. Using the Lewis lung carcinoma (LLC) model, we show that tumor growth induces a progressive increase in peripheral inflammation as observed by elevated interleukin-6 (IL-6). In behavioral studies, tumor-bearing mice showed no sign of motor, coordination or short term working memory deficits as assessed by rotarod, balance-beam, and novel object recognition tests. However, there was an impairment in the grip strength test and interestingly, an anxious and despair-like phenotype in the elevated plus-maze, and tail suspension tests, respectively. Immunostaining of perfused brains revealed fibrin accumulation in the vasculature with some leakage into the parenchyma, a process known to activate endothelial cells. Taken together, our results suggest that the inflamed and prothrombotic systemic environment created by the growth of a peripherally-located solid tumor induces endothelial activation, accumulation of fibrin in the brain and astrocyte activation, perhaps leading to depressive-like behavior.

Sevoflurane attenuates systemic inflammation compared with propofol, but does not modulate neuro-inflammation: A laboratory rat study

BACKGROUND

Septic encephalopathy is believed to be a result of neuro-inflammation possibly triggered by endotoxins, such as lipopolysaccharides (LPS). Modulation of the immune system is a property of volatile anaesthetics.

OBJECTIVE

We aimed to investigate the systemic and cerebral inflammatory response in a LPS-induced sepsis model in rats. We compared two different sedation strategies, intravenous propofol and the volatile anaesthetic sevoflurane, with the hypothesis that the latter may attenuate neuro-inflammatory processes.

DESIGN

Laboratory rat study.

SETTING

Basic research laboratories at the University Hospital Zurich and University Zurich Irchel between August 2014 and June 2016.

PATIENTS

A total of 32 adult male Wistar rats.

INTERVENTIONS

After tracheotomy and mechanical ventilation, the anaesthetised rats were monitored before sepsis was induced by using intravenous LPS or phosphate-buffered saline as control. Rats were sedated with propofol (10 mg kg h) or sevoflurane (2 vol%) continuously for 12 h.

MAIN OUTCOME MEASURES

Systemic inflammatory markers such as cytokine-induced neutrophil chemo-attractant protein 1, monocyte chemo-tactic protein-1 and IL-6 were determined. The same cytokines were measured in brain tissue. Cellular response in the brain was assessed by defining neutrophil accumulation with myeloperoxidase and also activation of microglia with ionised calcium-binding adaptor molecule-1 and astrocytes with glial fibrillary acidic protein. Finally, brain injury was determined.

RESULTS

Animals were haemodynamically stable in both sedation groups treated with LPS. Blood cytokine peak values were lower in the sevoflurane-LPS compared with propofol-LPS animals. In brain tissue of LPS animals, chemoattractant protein-1 was the only significantly increased cytokine (P = 0.003), however with no significance between propofol and sevoflurane. After LPS challenge, cerebral accumulation of neutrophils was observed. Microglia activation was pronounced in the hippocampus of animals treated with LPS (P = 0.006). LPS induced prominent astrogliosis (P < 0.001). There was no significant difference in microglia or astrocyte activation or apoptosis in the brain between sevoflurane and propofol.

CONCLUSION

We have shown that systemic attenuation of inflammation by the volatile anaesthetic sevoflurane did not translate into attenuated neuro-inflammation in this LPS-induced inflammation model.

TRIAL REGISTRATION

Animal approval No. 134/2014, Veterinäramt Zürich.

BML-111 Reduces Neuroinflammation and Cognitive Impairment in Mice With Sepsis via the SIRT1/NF-κB Signaling Pathway

Sepsis is a life-threatening state of organ dysfunction caused by infection and which can induce severe neurological disorders that lead to neuroinflammation and cognitive impairment. Inflammation has been reported to cause neuronal apoptosis in sepsis, which can finally lead to cognitive impairment. Previous studies have suggested that BML-111 can exhibit anti-inflammatory and proresolution activities. Additionally, silent information regulator 1 (SIRT1) can inhibit the NF-κB signaling pathway in an inflammation state. However, the role of the SIRT1/NF-κB signaling pathway in the protective effects of BML-111 against sepsis-induced neuroinflammation and cognitive impairment remains unclear. This study aimed to determine the effects of BML-111 on neuroinflammation and cognitive impairment induced by sepsis. Male C57BL/6J mice were subjected to cecal ligation and puncture (CLP) or a sham operation. BML-111 was administered via intracerebroventricular injection (0.1 mg/kg) immediately after CLP. Boc-2 (50 μg/kg) was administered intracerebroventricularly 30 min before CLP, and EX527 (10 μg) was administered every 2 days for a total of three times before CLP, also intracerebroventricularly. Some of the surviving mice underwent open-field, novel-object-recognition, and fear-conditioning behavioral tests at 7 days after surgery. Some of the other surviving mice were killed at 24 h after surgery to assess synaptic damage (PSD95 and Synapsin1), markers of inflammation [tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1β], cytoplasmic p65, nuclear p65, Ac- NF-κB and SIRT1. At 48 h after CLP, TUNEL and glia-activation by immunofluorescence investigations were performed on a separate cohort of surviving animals. The results suggested that sepsis resulted in cognitive impairment, which was accompanied by the decreased the expression of PSD95 and Synapsin1, increased amount of TUNEL-positive cells and the activation of glias, increased production of TNF-α and IL-1β, increased expression of nuclear p65, Ac- NF-κB, and decreased expression of SIRT1 and cytoplasmic p65. It is especially notable that these abnormalities could be reduced by BML-111 treatment. EX527, an SIRT1 inhibitor, abolished the effects of BML-111. These results demonstrate that BML-111 can reduce the neuroinflammation and cognitive impairment induced by sepsis via SIRT/NF-κB signaling pathway.

Sevoflurane exerts brain-protective effects against sepsis-associated encephalopathy and memory impairment through caspase 3/9 and Bax/Bcl signaling pathway in a rat model of sepsis

Objective We compared the effects of sevoflurane and isoflurane on systemic inflammation, sepsis-associated encephalopathy, and memory impairment in a rat sepsis model of cecal ligation and puncture (CLP)-induced polymicrobial peritonitis. Methods Twenty-four rats were assigned to sham, CLP, CLP + sevoflurane, and CLP + isoflurane groups. At 72 hours after CLP, the rats underwent behavior tests. Serum cytokines were evaluated. Brain tissue samples were collected for determination of glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase; the wet/dry weight ratio; myeloperoxidase (MPO) and malondialdehyde (MDA); apoptotic gene release; and histologic examinations. Results The MPO level, wet/dry weight ratio, and histopathology scores were lower and the Bcl2a1 and Bcl2l2 expressions were upregulated in both the CLP + sevoflurane and CLP + isoflurane groups compared with the CLP group. The interleukin-6, interleukin-1β, MDA, and caspase 3, 8, and 9 levels were lower; the GPX, SOD, Bax, Bcl2, and Bclx levels were higher; and non-associative and aversive memory were improved in the CLP + sevoflurane group compared with the CLP + isoflurane group. Conclusion Sevoflurane decreased apoptosis and oxidative injury and improved memory in this experimental rat model of CLP. Sevoflurane sedation may protect against brain injury and memory impairment in septic patients.

Parkinson disease-induced upregulation of apoptotic mediators could be attenuated in the skeletal muscle following chronic exercise training

BACKGROUND

We have shown elevated levels of p53 and active caspase-3 in gastrocnemius skeletal muscle with Parkinson's disease (PD). The main aim of this study is to examine the impact of endurance exercise training on the expression of p53 and active caspase-3 in the skeletal muscle of mouse with induced Parkinsonism.

METHODS

Sedentary control (SC), sedentary Parkinson diseased (SPD), and exercised Parkinson diseased (EPD) groups were formed; each consisting of 10 randomly selected normal albino mice. Chronic Parkinson disease was induced in the SPD and EPD animals using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid (MPTP/p). The expression of p53 and active caspase-3 was investigated, using immunohistochemistry, in the gastrocnemius muscle in each animal group.

RESULTS

Both p53 and active caspase-3 expression was significantly (p value < 0.05) reduced in the PD gastrocnemius skeletal muscle following endurance exercise training.

CONCLUSION

Our present data suggest that chronic exercise training reduced Parkinson disease-induced upregulation of p53 and active caspase-3 in gastrocnemius skeletal muscle. Thus, our study suggests that inhibiting p53 and/or active caspase-3 may be considered as a therapeutic approach to ameliorate PD skeletal muscle abnormalities.

Redox Signaling in Neurotransmission and Cognition During Aging

SIGNIFICANCE

Oxidative stress increases in the brain with aging and neurodegenerative diseases. Previous work emphasized irreversible oxidative damage in relation to cognitive impairment. This research has evolved to consider a continuum of alterations, from redox signaling to oxidative damage, which provides a basis for understanding the onset and progression of cognitive impairment. This review provides an update on research linking redox signaling to altered function of neural circuits involved in information processing and memory. Recent Advances: Starting in middle age, redox signaling triggers changes in nervous system physiology described as senescent physiology. Hippocampal senescent physiology involves decreased cell excitability, altered synaptic plasticity, and decreased synaptic transmission. Recent studies indicate N-methyl-d-aspartate and ryanodine receptors and Ca²⁺ signaling molecules as molecular substrates of redox-mediated senescent physiology.

CRITICAL ISSUES

We review redox homeostasis mechanisms and consider the chemical character of reactive oxygen and nitrogen species and their role in regulating different transmitter systems. In this regard, senescent physiology may represent the co-opting of pathways normally responsible for feedback regulation of synaptic transmission. Furthermore, differences across transmitter systems may underlie differential vulnerability of brain regions and neuronal circuits to aging and disease.

FUTURE DIRECTIONS

It will be important to identify the intrinsic mechanisms for the shift in oxidative/reductive processes. Intrinsic mechanism will depend on the transmitter system, oxidative stressors, and expression/activity of antioxidant enzymes. In addition, it will be important to identify how intrinsic processes interact with other aging factors, including changes in inflammatory or hormonal signals. Antioxid. Redox Signal. 28, 1724-1745.

Minocycline Prevents the Impairment of Hippocampal Long-Term Potentiation in the Septic Mouse

Sepsis-associated encephalopathy is a major complication during sepsis, and an effective treatment remains unknown. Although minocycline (MINO) has neuroprotective effects and is an attractive candidate for treating sepsis-associated encephalopathy, the effect of MINO on synaptic plasticity during sepsis is still unclear. In the present study, we investigated the effects of MINO on long-term potentiation (LTP) in the hippocampus in a cecal ligation and puncture (CLP) mouse model. We divided mice into four groups; sham + vehicle, sham + MINO (60 mg/kg, i.p. for 3 consecutive days before slice preparation), CLP + vehicle, and CLP + MINO. We tested LTP in the CA1 region of the hippocampus, using slices taken 24 h after surgery. Because MINO is also anti-inflammatory, LTP was analyzed following 30 min of IL-1 receptor antagonist (IL-1ra) perfusion. The endotoxin level in the blood was increased at 24 h after CLP operations regardless of MINO administrations, and LTP in the CLP + vehicle group mice was severely impaired (P < 0.05). High doses of MINO prevented the LTP impairment during sepsis in the CLP + MINO group. Interleukin (IL)-1ra administration ameliorated LTP impairment only in the CLP + vehicle group (P < 0.05); it had no additional effects on LTP in the CLP + MINO group. In conclusion, we have provided the first evidence that MINO prevents impaired LTP related to sepsis-induced encephalopathy in the mouse hippocampus, and that mechanisms associated with IL-1 receptor activity may be involved.

Improving Recovery and Outcomes Every Day after the ICU (IMPROVE): study protocol for a randomized controlled trial

Background

Delirium affects nearly 70% of older adults hospitalized in the intensive care unit (ICU), and many of those will be left with persistent cognitive impairment or dementia. There are no effective and scalable recovery models to remediate ICU-acquired cognitive impairment and its attendant elevated risk for dementia or Alzheimer disease (AD). The Improving Recovery and Outcomes Every Day after the ICU (IMPROVE) trial is an ongoing clinical trial which evaluates the efficacy of a combined physical exercise and cognitive training on cognitive function among ICU survivors 50 years and older who experienced delirium during an ICU stay. This article describes the study protocol for IMPROVE.

Methods

IMPROVE is a four-arm, randomized controlled trial. Subjects will be randomized to one of four arms: cognitive training and physical exercise; cognitive control and physical exercise; cognitive training and physical exercise control; and cognitive control and physical exercise control. Facilitators administer the physical exercise and exercise control interventions in individual and small group formats by using Internet-enabled videoconference. Cognitive training and control interventions are also facilitator led using Posit Science, Inc. online modules delivered in individual and small group format directly into the participants’ homes. Subjects complete cognitive assessment, mood questionnaires, physical performance batteries, and quality of life scales at baseline, 3, and 6 months. Blood samples will also be taken at baseline and 3 months to measure pro-inflammatory cytokines and acute-phase reactants; neurotrophic factors; and markers of glial dysfunction and astrocyte activation.

Discussion

This study is the first clinical trial to examine the efficacy of combined physical and cognitive exercise on cognitive function in older ICU survivors with delirium. The results will provide information about potential synergistic effects of a combined intervention on a range of outcomes and mechanisms of action.

Trial registration

ClinicalTrials.gov, NCT03095417. Registered on 23 March 2017. Last updated on 15 May 2017.

Electronic supplementary material

The online version of this article (10.1186/s13063-018-2569-8) contains supplementary material, which is available to authorized users.

The influence of immunological stressors on traumatic brain injury

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide, and typically involves a robust immune response. Although a great deal of preclinical research has been conducted to identify an effective treatment, all phase III clinical trials have been unsuccessful to date. These translational shortcomings are in part due to a failure to recognize and account for the heterogeneity of TBI, including how extracranial factors can influence the aftermath of TBI. For example, most preclinical studies have utilized isolated TBI models in young adult males, while clinical trials typically involve highly heterogeneous patient populations (e.g., different mechanisms of injury, a range of ages, presence of polytrauma or infection). This paper will review the current, albeit limited literature related to how TBI is affected by common concomitant immunological stressors. In particular, discussion will focus on whether extracranial trauma (i.e., polytrauma), infection, and age/immunosenescence can influence TBI pathophysiology, and thereby may result in a different brain injury than what would have occurred in an isolated TBI. It is concluded that these immunological stressors are all likely to be TBI modifiers that should be further studied and could impact translational treatment strategies.

Revisiting the systemic lipopolysaccharide mediated neuroinflammation: Appraising the effect of l-cysteine mediated hydrogen sulphide on it

The present research was ventured to examine the effect of l-cysteine on neuro-inflammation persuaded by peripheral lipopolysaccharides (LPS, 125 μg/kg, i.p.) administration. No behavioral, biochemical, and inflammatory abnormality was perceived in the brain tissues of experimental animals after LPS administration. l-cysteine precipitated marginal symptoms of toxicity in the brain tissue. Similar pattern of wholesome effect of LPS were perceived when evaluated through the brain tissue fatty acid profile, histopathologically and NF-ĸBP65 protein expression. LPS was unsuccessful to alter the levels of hydrogen sulphide (H₂S), cyclooxygenase (COX) and lipoxygenase (LOX) enzyme in brain tissue. LPS afforded significant peripheral toxicity, when figured out through inflammatory markers (COX, LOX), gaseous signaling molecules nitric oxide (NO), H₂S, liver toxicity (SGOT, SGPT), and inflammatory transcription factor (NF-ĸBP65) and l-cysteine also provided a momentous protection against the same as well. The study inculcated two major finding, firstly LPS (i.p.) cannot impart inflammatory changes to brain and secondly, l-cysteine can afford peripheral protection against deleterious effect of LPS (i.p.)