Dysfunction of inflammation-resolving pathways is associated with exaggerated postoperative cognitive decline in a rat model of the metabolic syndrome

J147 affects cognition and anxiety after surgery in Zucker rats

Vulnerable patients are at risk for neuroinflammation-mediated post-operative complications, including depression (POD) and cognitive dysfunction (POCD). Zucker rats, expressing multiple risk factors for post-operative complications in humans, may provide a clinically relevant model to study pathophysiology and explore potential interventions. J147, a newly developed anti-dementia drug, was shown to prevent POCD in young healthy rats, and improved early post-surgical recovery in Zucker rats. Aim of the present study was to investigate POCD and the therapeutic potential of J147 in male Zucker rats. Risk factors in the Zucker rat strain were evaluated by comparison with lean littermates. Zucker rats were subjected to major abdominal surgery. Acute J147 treatment was provided by a single iv injection (10 mg/kg) at the start of surgery, while chronic J147 treatment was provided in the food (aimed at 30 mg/kg/day), starting one week before surgery and up to end of protocol. Effects on behavior were assessed, and plasma, urine and brain tissue were collected and processed for immunohistochemistry and molecular analyses. Indeed, Zucker rats displayed increased risk factors for POCD, including obesity, high plasma triglycerides, low grade systemic inflammation, impaired spatial learning and decreased neurogenesis. Surgery in Zucker rats reduced exploration and increased anxiety in the Open Field test, impaired short-term spatial memory, induced a shift in circadian rhythm and increased plasma neutrophil gelatinase-associated lipocalin (NGAL), microglia activity in the CA1 and blood brain barrier leakage. Chronic, but not acute J147 treatment reduced anxiety in the Open Field test and protected against the spatial memory decline. Moreover, chronic J147 increased glucose sensitivity. Acute J147 treatment improved long-term spatial memory and reversed the circadian rhythm shift. No anti-inflammatory effects were seen for J147. Although Zucker rats displayed risk factors, surgery did not induce extensive POCD. However, increased anxiety may indicate POD. Treatment with J147 showed positive effects on behavioral and metabolic parameters, but did not affect (neuro)inflammation. The mixed effect of acute and chronic treatment may suggest a combination for optimal treatment.

Leukotriene signaling as molecular correlate for cognitive heterogeneity in aging: an exploratory study

Introduction

Aging is in general associated with a decline in cognitive functions. Looking more closely, there is a huge heterogeneity in the extent of cognitive (dys-)abilities in the aged population. It ranges from the population of resistant, resilient, cognitively unimpaired individuals to patients with severe forms of dementias. Besides the known genetic, environmental and life style factors that shape the cognitive (dys-)abilities in aging, the underlying molecular mechanisms and signals related to cognitive heterogeneity are completely unknown. One putative mechanism underlying cognitive heterogeneity might be neuroinflammation, exerted through microglia, the brain's innate immune cells, as neuroinflammation is central to brain aging and neurodegenerative diseases. Recently, leukotrienes (LTs), i.e., small lipid mediators of inflammation produced by microglia along aging and neurodegeneration, got in the focus of geroscience as they might determine cognitive dysfunctions in aging.

Methods

Here, we analyzed the brain's expression of key components of the LT synthesis pathway, i.e., the expression of 5-lipoxygenase (5-Lox), the key enzyme in LT production, and 5-lipoxygenase-activating protein (FLAP) in young and aged rats. More specifically, we used a cohort of rats, which, although grown up and housed under identical conditions, developed into aged cognitively unimpaired and aged cognitively impaired traits.

Results

Expression of 5-Lox was increased within the brain of aged rats with the highest levels detected in cognitively impaired animals. The number of microglia cells was higher in the aged compared to the young brains with, again, the highest numbers of 5-Lox expressing microglia in the aged cognitively impaired rats. Remarkably, lower cognitive scores in the aged rats associated with higher numbers of 5-Lox positive microglia in the animals. Similar data were obtained for FLAP, at least in the cortex. Our data indicate elevated levels of the LT system in the brain of cognitively impaired animals.

Discussion

We conclude that 5-Lox expressing microglia potentially contribute to the age-related cognitive decline in the brain, while low levels of the LT system might indicate and foster higher cognitive functions and eventually cognitive reserve and resilience in aging.

Metabolic syndrome and the risk of postoperative delirium and postoperative cognitive dysfunction: a multi-centre cohort study

BACKGROUND

Metabolic syndrome and its components are risk factors for cognitive impairment, but their contribution to perioperative neurocognitive disorders is unknown. We examined their associations with the risk of postoperative delirium (POD) and postoperative cognitive dysfunction (POCD) in older patients.

METHODS

In 765 male and female participants aged ≥65 years, we measured preoperative metabolic parameters and screened for POD for 7 days or until discharge. POCD was defined through comparison of cognitive change on six neuropsychological tests with non-surgical controls. Multiple logistic regression analyses examined the association of metabolic parameters with risk of POD and POCD with adjustment for age, sex, and surgery type.

RESULTS

A total of 149 patients (19.5% of 765) developed POD and 53 (10.1% of 520 attendees) had POCD at 3 months. Patients with metabolic syndrome were at 1.85-fold higher risk of POD (95% confidence interval [CI] 1.26-2.70). Each 1 mmol L^-1 higher high-density lipoprotein cholesterol (HDL-C) was associated with a 0.47-fold lower POD risk (95% CI 0.30-0.74). Each 1 kg m^-2 higher body mass index (BMI) was associated with a 1.09-fold higher POCD risk (95% CI 1.02- 1.16).

CONCLUSIONS

Older surgical patients with metabolic syndrome were at increased risk of POD. Only reduced HDL-C was significantly associated with POD. For POCD, a higher preoperative BMI was identified as a risk factor. These findings add to mounting evidence of a distinct epidemiology of POD and POCD. Screening programmes taking advantage of HDL-C and BMI measurements and of metabolic interventions in reducing perioperative neurocognitive disorders should be evaluated.

CLINICAL TRIAL REGISTRATION

NCT02265263.

Age-Related Perioperative Neurocognitive Disorders: Experimental Models and Druggable Targets

With the worldwide increase in life span, surgical patients are becoming older and have a greater propensity for postoperative cognitive impairment, either new onset or through deterioration of an existing condition; in both conditions, knowledge of the patient's preoperative cognitive function and postoperative cognitive trajectory is imperative. We describe the clinical utility of a tablet-based technique for rapid assessment of the memory and attentiveness domains required for executive function. The pathogenic mechanisms for perioperative neurocognitive disorders have been investigated in animal models in which excessive and/or prolonged postoperative neuroinflammation has emerged as a likely contender. The cellular and molecular species involved in postoperative neuroinflammation are the putative targets for future therapeutic interventions that are efficacious and do not interfere with the surgical patient's healing process.

Effect of Preoperative Oral Saline Administration on Postoperative Delirium in Older Persons: A Randomized Controlled Trial

Objective

Postoperative delirium (POD) seriously affects recovery of older persons, increasing their mortality rate after surgery. We aimed to evaluate preoperative oral saline administration on postoperative delirium in older persons undergoing spinal decompression.

Design

A randomised controlled trial in a large tertiary hospital.

Setting and Participants

A total of 76 older persons (≧65 years old) undergoing spinal surgery from May 2020 to January 2021.

Methods

Older persons (65–83 years old) who underwent elective spinal canal decompression were randomly grouped into either the control group (n = 38) or the intervention group (n = 38). The control group was forbidden from drinking 8 hours prior to the operation while the intervention group was administered 5 mL·kg⁻¹ of normal saline 2 hours before anesthesia. Hemodynamic indicators, diagnostic biomarkers, preoperative mini-mental status scores, and intraoperative fluid dynamics were recorded at baseline and at various postoperative timepoints. Subjects were then scored for POD and postoperative pain.

Results

S100β protein was lowered in S₁ (F_S1 = 12.289, P <0.001) and S₂ (F_S2 = 12.440, P <0.001) in the intervention group while mean arterial blood pressure (F_T1= 42.997, P<0.001) and heart rate (F_T1= 8.974, P=0.004) were increased. The Ln c-reactive protein of the intervention group was lowered 1 day postoperatively (F_S2 = 6.305, P = 0.014). The incidence of postoperative delirium in the control group was higher than in the intervention group (27.8% vs 8.3%, χ² = 4.547, P = 0.033).

Conclusion

Preoperative oral saline can reduce the incidence of postoperative delirium in older persons by minimizing perioperative hemodynamic fluctuations and central nervous system damage.

Dexmedetomidine Prevents Cognitive Decline by Enhancing Resolution of High Mobility Group Box 1 Protein-induced Inflammation through a Vagomimetic Action in Mice

BACKGROUND

Inflammation initiated by damage-associated molecular patterns has been implicated for the cognitive decline associated with surgical trauma and serious illness. We determined whether resolution of inflammation mediates dexmedetomidine-induced reduction of damage-associated molecular pattern-induced cognitive decline.

METHODS

Cognitive decline (assessed by trace fear conditioning) was induced with high molecular group box 1 protein, a damage-associated molecular pattern, in mice that also received blockers of neural (vagal) and humoral inflammation-resolving pathways. Systemic and neuroinflammation was assessed by proinflammatory cytokines.

RESULTS

Damage-associated molecular pattern-induced cognitive decline and inflammation (mean ± SD) was reversed by dexmedetomidine (trace fear conditioning: 58.77 ± 8.69% vs. 41.45 ± 7.64%, P < 0.0001; plasma interleukin [IL]-1β: 7.0 ± 2.2 pg/ml vs. 49.8 ± 6.0 pg/ml, P < 0.0001; plasma IL-6: 3.2 ± 1.6 pg/ml vs. 19.5 ± 1.7 pg/ml, P < 0.0001; hippocampal IL-1β: 4.1 ± 3.0 pg/mg vs. 41.6 ± 8.0 pg/mg, P < 0.0001; hippocampal IL-6: 3.4 ± 1.3 pg/mg vs. 16.2 ± 2.7 pg/mg, P < 0.0001). Reversal by dexmedetomidine was prevented by blockade of vagomimetic imidazoline and α7 nicotinic acetylcholine receptors but not by α2 adrenoceptor blockade. Netrin-1, the orchestrator of inflammation-resolution, was upregulated (fold-change) by dexmedetomidine (lung: 1.5 ± 0.1 vs. 0.7 ± 0.1, P < 0.0001; spleen: 1.5 ± 0.2 vs. 0.6 ± 0.2, P < 0.0001), resulting in upregulation of proresolving (lipoxin-A4: 1.7 ± 0.2 vs. 0.9 ± 0.2, P < 0.0001) and downregulation of proinflammatory (leukotriene-B4: 1.0 ± 0.2 vs. 3.0 ± 0.3, P < 0.0001) humoral mediators that was prevented by α7 nicotinic acetylcholine receptor blockade.

CONCLUSIONS

Dexmedetomidine resolves inflammation through vagomimetic (neural) and humoral pathways, thereby preventing damage-associated molecular pattern-mediated cognitive decline.

Neuroinflammation is a putative target for the prevention and treatment of perioperative neurocognitive disorders

INTRODUCTION

The demographics of aging of the surgical population has increased the risk for perioperative neurocognitive disorders in which trauma-induced neuroinflammation plays a pivotal role.

SOURCES OF DATA

After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered.

AREAS OF AGREEMENT

Neuroinflammation is a sine qua non for development of perioperative neurocognitive disorders.

AREAS OF CONTROVERSY

What is the best method for ameliorating trauma-induced neuroinflammation while preserving inflammation-based wound healing.

GROWING POINTS

This review considers how to prepare for and manage the vulnerable elderly surgical patient through the entire spectrum, from preoperative assessment to postoperative period.

AREAS TIMELY FOR DEVELOPING RESEARCH

What are the most effective and safest interventions for preventing and/or reversing Perioperative Neurocognitive Disorders.

Annexin A1 Bioactive Peptide Promotes Resolution of Neuroinflammation in a Rat Model of Exsanguinating Cardiac Arrest Treated by Emergency Preservation and Resuscitation

Neuroinflammation initiated by damage-associated molecular patterns, including high mobility group box 1 protein (HMGB1), has been implicated in adverse neurological outcomes following lethal hemorrhagic shock and polytrauma. Emergency preservation and resuscitation (EPR) is a novel method of resuscitation for victims of exsanguinating cardiac arrest, shown in preclinical studies to improve survival with acceptable neurological recovery. Sirtuin 3 (SIRT3), the primary mitochondrial deacetylase, has emerged as a key regulator of metabolic and energy stress response pathways in the brain and a pharmacological target to induce a neuronal pro-survival phenotype. This study aims to examine whether systemic administration of an Annexin-A1 bioactive peptide (ANXA1sp) could resolve neuroinflammation and induce sirtuin-3 regulated cytoprotective pathways in a novel rat model of exsanguinating cardiac arrest and EPR. Adult male rats underwent hemorrhagic shock and ventricular fibrillation, induction of profound hypothermia, followed by resuscitation and rewarming using cardiopulmonary bypass (EPR). Animals randomly received ANXA1sp (3 mg/kg, in divided doses) or vehicle. Neuroinflammation (HMGB1, TNFα, IL-6, and IL-10 levels), cerebral cell death (TUNEL, caspase-3, pro and antiapoptotic protein levels), and neurologic scores were assessed to evaluate the inflammation resolving effects of ANXA1sp following EPR. Furthermore, western blot analysis and immunohistochemistry were used to interrogate the mechanisms involved. Compared to vehicle controls, ANXA1sp effectively reduced expression of cerebral HMGB1, IL-6, and TNFα and increased IL-10 expression, which were associated with improved neurological scores. ANXA1sp reversed EPR-induced increases in expression of proapoptotic protein Bax and reduction in antiapoptotic protein Bcl-2, with a corresponding decrease in cerebral levels of cleaved caspase-3. Furthermore, ANXA1sp induced autophagic flux (increased LC3II and reduced p62 expression) in the brain. Mechanistically, these findings were accompanied by upregulation of the mitochondrial protein deacetylase Sirtuin-3, and its downstream targets FOXO3a and MnSOD in ANXA1sp-treated animals. Our data provide new evidence that engaging pro-resolving pharmacological strategies such as Annexin-A1 biomimetic peptides can effectively attenuate neuroinflammation and enhance the neuroprotective effects of EPR after exsanguinating cardiac arrest.

The presence of elevated circulating trimethylamine N-oxide exaggerates postoperative cognitive dysfunction in aged rats

Surgical trauma can cause brain oxidative stress and neuroinflammation, leading to postoperative cognitive dysfunction (POCD), especially in the elderly. Additionally, the pre-existing risk factors may enhance POCD. Gut microbiota-derived metabolite trimethylamine N-oxide (TMAO) has recently been shown to contribute to the pathogenesis of many diseases by increasing oxidative stress and inflammation in the peripheral tissues. Here we examined whether the presence of elevated circulating TMAO would influence surgery-induced cognitive decline. Aged rats were treated with vehicle or TMAO for 3 weeks. After two weeks of treatment, these rats underwent sham-operation or laparotomy. One week after surgery, rats underwent laparotomy exhibited hippocampal-dependent cognitive dysfunction as evidenced by reduced contextual freezing time, which was associated with elevated plasma proinflammatory cytokine levels, increased microglia-mediated neuroinflammation and reactive oxygen species (ROS) production in the hippocampus. Treatment with TMAO, which elevated plasma TMAO before and 1 week after surgery, further increased microglia-mediated neuroinflammation and ROS production in the hippocampus, resulting in exaggerated cognitive dysfunction in laparotomy group but not in sham-operation group. Moreover, TMAO treatment decreased expression of antioxidant enzyme methionine sulfoxide reductase (Msr) A in both groups. The results suggest that the presence of elevated circulating TMAO downregulates antioxidant enzyme MsrA in the hippocampus, which may increase the susceptibility to surgery-induced oxidative stress, contributing to exaggerations of neuroinflammation and cognitive decline in aged rats following surgery. Interventions to reduce circulating TMAO in the perioperative period may be a novel strategy to prevent the exaggeration of cognitive decline in elderly patients with high circulating TMAO.

Influence of metabolic syndrome on the relationship between fatty acids and the selected parameters in men with benign prostatic hyperplasia

The purpose of our investigation was to analyze the relationship between the serum levels of fatty acids and their metabolites and the levels of the selected metabolic and hormonal parameters in patients with benign prostatic hyperplasia (BPH) with regard to concomitant metabolic syndrome (MetS). We determined serum concentrations of total (TT) and free testosterone (FT), insulin (I), dehydroepiandrosterone sulphate (DHEAS), luteinizing hormone and insulin-like growth factor 1 (IGF-1) and sex hormone-binding globulin (SHBG). Gas chromatography was performed. The patients differed in terms of hormone levels, but only the differences in SHBG and IGF-1 levels were statistically significant. Analysis of the levels of polysaturated fatty acids in BPH patients showed that MetS contributed to changes in the levels of these acids. We also analyzed the relationship between the levels of fatty acids and diagnostic parameters for MetS. Particular abnormalities were associated with single changes in the levels of fatty acids. In the diabetic patients, changes in the levels of pentadecanoic acid, heptadecanoic acid and cis-11-eicosenoic acid were demonstrated. Our findings indicate the necessity for further investigation concerning the levels of fatty acids and their impact on the development of MetS, as well as the course and clinical picture of BPH.

Effect of parecoxib in the treatment of postoperative cognitive dysfunction: A systematic review and meta-analysis

BACKGROUND

Parecoxib is a selective cyclooxygenase (COX)-2 inhibitor widely used as an analgesia technique in perioperative period for its potent anti-inflammatory and analgesic effects. However, litter is known about its effect on postoperative cognitive dysfunction (POCD). The purpose of this meta-analysis of randomized controlled trials (RCTs) was to evaluate the effect of parecoxib in the treatment of postoperative cognitive dysfunction.

METHODS

We searched PubMed, Cochrane Library and Embase databases for relevant studies up to October 2017. We selected fixed-effect model for analysis of data heterogeneity. Statistical analyses were performed by using Review Manager Version 5.3 for Windows.

RESULTS

Four RCTs with 904 patients that underwent surgical operations were included. The meta-analysis demonstrated parecoxib could significantly decrease the incidence of POCD on postoperative day 1, day 3, day 5, and day 7 when compared with control treatment; IL-6 and S100β concentrations were lower up to postoperative day 2. The consumption of morphine, fentanyl and tramadol in parecoxib groups were lower than control groups.

CONCLUSION

Our meta-analysis suggested that the administration of Parecoxib was effective in treating early POCD within 7 days and reducing IL-6 and S100β concentrations within 2 days after operations. Nevertheless, our current study with some limitations such as the small sample size only provided limited quality of evidence, confirmation from further meta-analysis with large-scale, well-designed RCTs is required.

The Evolving Role of Specialized Pro-resolving Mediators in Modulating Neuroinflammation in Perioperative Neurocognitive Disorders

Surgery can be a life-saving procedure; however, significant complications may occur after routine procedures especially in older and more frail patients. Perioperative neurocognitive disorders (PNDs), including delirium and postoperative cognitive dysfunction, are the most common complications in older adults following common procedures such as orthopedic or cardiac surgery. The consequences of PNDs can be devastating, with longer in-hospital stay, poorer prognosis, and higher mortality rates. Inflammation is gaining considerable interest as a critical driver of cognitive deficits. In this regard, resolution of inflammation, once thought to be a passive process, may provide novel approaches to treat neuroinflammation and PNDs. Herein we review the role for impaired resolution after surgery and the growing role of specialized pro-resolving mediators (SPMs) in regulating postoperative neuroinflammation and neurological complications after surgery.

Tacrine(10)-Hupyridone Prevents Post-operative Cognitive Dysfunction via the Activation of BDNF Pathway and the Inhibition of AChE in Aged Mice

Post-operative cognitive dysfunction (POCD) could cause short-term or long-term cognitive disruption lasting weeks or months after anesthesia and surgery in elderly. However, no effective treatment of POCD is currently available. Previous studies indicated that the enhancement of brain-derived neurotrophic factor (BDNF) expression, and the elevation the cholinergic system, might be effective to prevent POCD. In this study, we have discovered that tacrine(10)-hupyridone (A10E), a novel acetylcholinesterase (AChE) inhibitor derived from tacrine and huperzine A, could prevent surgery-induced short-term and long-term impairments of recognition and spatial cognition, as evidenced by the novel object recognition test and Morris water maze (MWM) tests, in aged mice. Moreover, A10E significantly increased the expression of BDNF and activated the downstream Akt and extracellular regulated kinase (ERK) signaling in the surgery-treated mice. Furthermore, A10E substantially enhanced choline acetyltransferase (ChAT)-positive area and decreased AChE activity, in the hippocampus regions of surgery-treated mice, indicating that A10E could prevent surgery-induced dysfunction of cholinergic system, possibly via increasing the synthesis of acetylcholine and the inhibition of AChE. In conclusion, our results suggested that A10E might prevent POCD via the activation of BDNF pathway and the inhibition of AChE, concurrently, in aged mice. These findings also provided a support that A10E might be developed as a potential drug lead for POCD.

Neurocognitive Function after Cardiac Surgery: From Phenotypes to Mechanisms

For half a century, it has been known that some patients experience neurocognitive dysfunction after cardiac surgery; however, defining its incidence, course, and causes remains challenging and controversial. Various terms have been used to describe neurocognitive dysfunction at different times after cardiac surgery, ranging from "postoperative delirium" to "postoperative cognitive dysfunction or decline." Delirium is a clinical diagnosis included in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). Postoperative cognitive dysfunction is not included in the DSM-5 and has been heterogeneously defined, though a recent international nomenclature effort has proposed standardized definitions for it. Here, the authors discuss pathophysiologic mechanisms that may underlie these complications, review the literature on methods to prevent them, and discuss novel approaches to understand their etiology that may lead to novel treatment strategies. Future studies should measure both delirium and postoperative cognitive dysfunction to help clarify the relationship between these important postoperative complications.

Oxidative stress and mitochondrial dysfunction contributes to postoperative cognitive dysfunction in elderly rats

Postoperative cognitive dysfunction (POCD) is defined by cognitive impairment determined by neuropsychological tests from before to after surgery. Several mechanisms have been proposed in this bidirectional communication between the immune system and the brain after surgery. We aimed at understanding the mechanisms underlying POCD elderly rats in an experimental tibial fracture model. Elderly male Wistar rats were subjected to tibial fracture (TF) model. Control (sham) and fracture (TF) groups were followed to determine nitrite/nitrate concentration; oxidative damage to lipids and proteins; the activity of antioxidant enzymes (superoxide dismutase-SOD and catalase-CAT), mitochondrial respiratory chain enzymes, and creatine kinase (CK); and BDNF levels in the hippocampus and prefrontal cortex (at 24 h and at seven days) and cognitive function through habituation to the open field task and novel object recognition task (only at seven days). TF group presented increased concentration of nitrite/nitrate, hippocampal lipid peroxidation at seven days, protein oxidative damage in the prefrontal cortex and hippocampus at 24 h, decreased antioxidant activity in both structures on the first postoperative day and compromised function of the mitochondrial respiratory chain complexes as well as the CK enzyme. In addition, the levels of BDNF were reduced and memory function was impaired in the TF group. In conclusion, elderly rats submitted to an experimental model of tibial fracture displayed memory impairment accompanied by an increase in oxidative stress, mitochondrial dysfunction and reduced neurotrophin level.

Nicotinic Acetylcholine Receptors in HIV: Possible Roles During HAND and Inflammation

Infection with the human immunodeficiency virus (HIV) remains a threat to global health. Since its discovery, many efforts have been directed at understanding the mechanisms and consequences of infection. Although there have been substantial advances since the advent of antiretroviral therapy, there are still complications that significantly compromise the health of infected patients, particularly, chronic inflammation and HIV-associated neurocognitive disorders (HAND). In this review, a new perspective is addressed in the field of HIV, where the alpha7 nicotinic acetylcholine receptor (α7-nAChR) is the protagonist. We comprehensively discuss the available evidence implicating α7-nAChRs in the context of HIV and provide possible explanations about its role in HAND and inflammation in both the central nervous system and the periphery.

Dexmedetomidine restores septic renal function via promoting inflammation resolution in a rat sepsis model

BACKGROUND

Acute kidney injury occurred after sepsis, resulting in high mortality. This research aims to elucidate the mechanistic effect of DEX on the renal inflammation resolution during sepsis in rats.

METHODS

The rats were randomly divided into a sham group and the other three cecal ligation and puncture (CLP) model groups, based on different treatments: placebo, DEX and 2-adrenergic receptor (AR) inhibitor atipamezole (AT) treatment (DEX + AT) groups. The survival of septic rats within 24 h was recorded. Tissue pathology, plasma IL-1β, IL-6, TNF-α, lipoxygenase-5 and lipoxin A4 were evaluated. Western blotting and immunostaining was used to determine expression of TLR4, IκB, IKK, NF-κB p65 and pp65 in kidney tissue. Then qPCR was used to analyze the mRNA expression of renal α_2A-AR, α_2B-AR and α_2C-AR.

RESULTS

Rat mortality and kidney inflammation were significantly increased in septic rats. Specifically, IL-1β, IL-6 and TNF-α plasma levels, NF-κB activity, and TLR4 expression in rat kidney tissues were increased after CLP. In the DEX treatment group, mortality was reduced, histology changes were minor, and lipoxygenase-5, and lipoxin A4 expression were increased. The expression of IL-1β, IL-6 and TNF-α, NF-κB activity and TLR4 expression in rat kidney tissues were also decreased. These results indicated that DEX treatment alleviates acute kidney injury induced by CLP. However, the effects of DEX were apparently suppressed by atipamezole in the DEX + AT group.

CONCLUSION

The current study demonstrated the protective effect of DEX on CLP-induced kidney injury, which may be effective by attenuating NF-κB pathway activation with lipoxin A4.

Arachidonic acid in health and disease with focus on hypertension and diabetes mellitus: A review

Arachidonic acid (AA 20:4n-6) is an essential component of cell membranes and modulates cell membrane fluidity. AA is metabolized by cyclo-oxygenase (COX), lipoxygenase (LOX) and cytochrome P450 enzymes to form several metabolites that have important biological actions. Of all the actions, role of AA in the regulation of blood pressure and its ability to prevent both type 1 and type 2 diabetes mellitus seems to be interesting. Studies showed that AA and its metabolites especially, lipoxin A4 (LXA4) and epoxyeicosatrienoic acids (EETs), potent anti-inflammatory metabolites, have a crucial role in the pathobiology of hypertension and diabetes mellitus. AA, LXA4 and EETs regulate smooth muscle function and proliferation, voltage gated ion channels, cell membrane fluidity, membrane receptors, G-coupled receptors, PPARs, free radical generation, nitric oxide formation, inflammation, and immune responses that, in turn, participate in the regulation blood pressure and pathogenesis of diabetes mellitus. In this review, role of AA and its metabolites LXA4 and EETs in the pathobiology of hypertension, pre-eclampsia and diabetes mellitus are discussed. Based on several lines of evidences, it is proposed that a combination of aspirin and AA could be of benefit in the prevention and management of hypertension, pre-eclampsia and diabetes mellitus.

Screening of Potential Genes and Transcription Factors of Postoperative Cognitive Dysfunction via Bioinformatics Methods

Background

The aim of this study was to explore the potential genes and transcription factors involved in postoperative cognitive dysfunction (POCD) via bioinformatics analysis.

Material/Methods

GSE95070 miRNA expression profiles were downloaded from Gene Expression Omnibus database, which included five hippocampal tissues from POCD mice and controls. Moreover, the differentially expressed miRNAs (DEMs) between the two groups were identified. In addition, the target genes of DEMs were predicted using Targetscan 7.1, followed by protein-protein interaction (PPI) network construction, functional enrichment analysis, pathway analysis, and prediction of transcription factors (TFs) targeting the potential targets.

Results

A total of eight DEMs were obtained, and 823 target genes were predicted, including 170 POCD-associated genes. Furthermore, potential key genes in the network were remarkably enriched in focal adhesion, protein digestion and absorption, ECM-receptor interaction, and Wnt and MAPK signaling pathways.

Conclusions

Most potential target genes were involved in the regulation of TFs, including LEF1, SP1, and AP4, which may exert strong impact on the development of POCD.

Exercise Prevents Enhanced Postoperative Neuroinflammation and Cognitive Decline and Rectifies the Gut Microbiome in a Rat Model of Metabolic Syndrome

Introduction

Postoperative cognitive decline (PCD) can affect in excess of 10% of surgical patients and can be considerably higher with risk factors including advanced age, perioperative infection, and metabolic conditions such as obesity and insulin resistance. To define underlying pathophysiologic processes, we used animal models including a rat model of metabolic syndrome generated by breeding for a trait of low aerobic exercise tolerance. After 35 generations, the low capacity runner (LCR) rats differ 10-fold in their aerobic exercise capacity from high capacity runner (HCR) rats. The LCR rats respond to surgical procedure with an abnormal phenotype consisting of exaggerated and persistent PCD and failure to resolve neuroinflammation. We determined whether preoperative exercise can rectify the abnormal surgical phenotype.

Materials and methods

Following institutional approval of the protocol each of male LCR and male HCR rats were randomly assigned to four groups and subjected to isoflurane anesthesia and tibia fracture with internal fixation (surgery) or anesthesia alone (sham surgery) and to a preoperative exercise regimen that involved walking for 10 km on a treadmill over 6 weeks (exercise) or being placed on a stationary treadmill (no exercise). Feces were collected before and after exercise for assessment of gut microbiome. Three days following surgery or sham surgery the rats were tested for ability to recall a contextual aversive stimulus in a trace fear conditioning paradigm. Thereafter some rats were euthanized and the hippocampus harvested for analysis of inflammatory mediators. At 3 months, the remainder of the rats were tested for memory recall by the probe test in a Morris Water Maze.

Results

Postoperatively, LCR rats exhibited exaggerated cognitive decline both at 3 days and at 3 months that was prevented by preoperative exercise. Similarly, LCR rats had excessive postoperative neuroinflammation that was normalized by preoperative exercise. Diversity of the gut microbiome in the LCR rats improved after exercise.

Discussion

Preoperative exercise eliminated the metabolic syndrome risk for the abnormal surgical phenotype and was associated with a more diverse gut microbiome. Prehabilitation with exercise should be considered as a possible intervention to prevent exaggerated and persistent PCD in high-risk settings.

Perioperative management of the obese surgical patient

INTRODUCTION

The escalation in the prevalence of obesity throughout the world has led to an upsurge in the number of obese surgical patients to whom perioperative care needs to be delivered.

SOURCES OF DATA

After determining the scope of the review, the authors used PubMed with select phrases encompassing the words in the scope. Both preclinical and clinical reports were considered.

AREAS OF AGREEMENT

There were no controversies regarding preoperative management and the intraoperative care of the obese surgical patient.

AREAS OF CONTROVERSY

Is there a healthy obese state that gives rise to the obesity paradox regarding postoperative complications?

GROWING POINTS

This review considers how to prepare for and manage the obese surgical patient through the entire spectrum, from preoperative assessment to possible postoperative intensive care.

AREAS TIMELY FOR DEVELOPING RESEARCH

What results in an obese patient developing 'unhealthy' obesity?

Post-Operative Cognitive Dysfunction: An exploration of the inflammatory hypothesis and novel therapies

Post-Operative Cognitive Dysfunction (POCD) is a highly prevalent condition with significant clinical, social and financial impacts for patients and their communities. The underlying pathophysiology is becoming increasingly understood, with the role of neuroinflammation and oxidative stress secondary to surgery and anaesthesia strongly implicated. This review aims to describe the putative mechanisms by which surgery-induced inflammation produces cognitive sequelae, with a focus on identifying potential novel therapies based upon their ability to modify these pathways.

Rapamycin increases grip strength and attenuates age-related decline in maximal running distance in old low capacity runner rats

Rapamycin is known to extend lifespan. We conducted a randomized placebo-controlled study of enteric rapamycin-treatment to evaluate its effect on physical function in old low capacity runner (LCR) rats, a rat model selected from diverse genetic background for low intrinsic aerobic exercise capacity without genomic manipulation and characterized by increased complex disease risks and aging phenotypes. The study was performed in 12 male and 16 female LCR rats aged 16-22 months at baseline. The treatment group was fed with rapamycin-containing diet pellets at approximately 2.24mg/kg body weight per day and the placebo group with the same diet without rapamycin for six months. Observation was extended for additional 2 months. Physical function measurements include grip strength measured as maximum tensile force using a rat grip strength meter and maximum running distance (MRD) using rat physical treadmill test. The results showed that rapamycin improved grip strength by 13% (p=.036) and 60% (p<.001) from its baseline in female and male rats, respectively. Rapamycin attenuated MRD decline by 66% (p<.001) and 46% (p=.319) in females and males, respectively. These findings provide initial evidence for beneficial effect of rapamycin on physical functioning in an aging rat model of high disease risks with significant implication in humans.

The Effect of Propofol Versus Isoflurane Anesthesia on Human Cerebrospinal Fluid Markers of Alzheimer's Disease: Results of a Randomized Trial

BACKGROUND

Preclinical studies have found differential effects of isoflurane and propofol on the Alzheimer's disease (AD)-associated markers tau, phosphorylated tau (p-tau) and amyloid-β (Aβ).

OBJECTIVE

We asked whether isoflurane and propofol have differential effects on the tau/Aβ ratio (the primary outcome), and individual AD biomarkers. We also examined whether genetic/intraoperative factors influenced perioperative changes in AD biomarkers.

METHODS

Patients undergoing neurosurgical/otolaryngology procedures requiring lumbar cerebrospinal fluid (CSF) drain placement were prospectively randomized to receive isoflurane (n = 21) or propofol (n = 18) for anesthetic maintenance. We measured perioperative CSF sample AD markers, performed genotyping assays, and examined intraoperative data from the electronic anesthesia record. A repeated measures ANOVA was used to examine changes in AD markers by anesthetic type over time.

RESULTS

The CSF tau/Aβ ratio did not differ between isoflurane- versus propofol-treated patients (p = 1.000). CSF tau/Aβ ratio and tau levels increased 10 and 24 h after drain placement (p = 2.002×10-6 and p = 1.985×10-6, respectively), mean CSF p-tau levels decreased (p = 0.005), and Aβ levels did not change (p = 0.152). There was no interaction between anesthetic treatment and time for any of these biomarkers. None of the examined genetic polymorphisms, including ApoE4, were associated with tau increase (n = 9 polymorphisms, p > 0.05 for all associations).

CONCLUSION

Neurosurgery/otolaryngology procedures are associated with an increase in the CSF tau/Aβ ratio, and this increase was not influenced by anesthetic type. The increased CSF tau/Aβ ratio was largely driven by increases in tau levels. Future work should determine the functional/prognostic significance of these perioperative CSF tau elevations.

Rats bred for low and high running capacity display alterations in peripheral tissues and nerves relevant to neuropathy and pain

INTRODUCTION

Diet and activity are recognized as modulators of nervous system disease, including pain. Studies of exercise consistently reveal a benefit on pain. This study focused on female rats to understand differences related to metabolic status and peripheral nerve function in females.

METHODS

Here, we investigated parameters of peripheral nerve function relevant to pain in rats selectively bred for high (high-capacity runners; HCR) or low endurance exercise capacity (low-capacity runners; LCR) resulting in divergent intrinsic aerobic capacities and susceptibility for metabolic conditions.

RESULTS

LCR female rats have reduced mechanical sensitivity, higher intraepidermal nerve fiber density and TrkA-positive epidermal axons, increased numbers of Langerhans and mast cells in cutaneous tissues, and a higher fat content despite similar overall body weights compared to female HCR rats. Sensory and motor nerve conduction velocities, thermal sensitivity, and mRNA expression of selected genes relevant to peripheral sensation were not different.

CONCLUSIONS

These results suggest that aerobic capacity and metabolic status influence sensory sensitivity and aspects of inflammation in peripheral tissues that could lead to poor responses to tissue damage and painful stimuli. The LCR and HCR rats should prove useful as models to assess how the metabolic status impacts pain.

Microglia mediate postoperative hippocampal inflammation and cognitive decline in mice

Surgery can induce cognitive decline, a risk that increases with advancing age. In rodents, postoperative cognitive decline (POCD) is associated with the inflammatory activation of hippocampal microglia. To examine the role of microglia in POCD, we inhibited the colony-stimulating factor 1 receptor (CSF1R) in adult mice, effectively depleting CNS microglia. Surgical trauma (tibial fracture) reduced the ability of mice to remember a conditioned response learned preoperatively, a deficit more pronounced and persistent in mice with diet-induced obesity (DIO). Whereas microglial depletion by itself did not affect learning or memory, perioperative microglial depletion remarkably protected mice, including those with DIO, from POCD. This protection was associated with reduced hippocampal levels of inflammatory mediators, abrogation of hippocampal recruitment of CCR2⁺ leukocytes, and higher levels of circulating inflammation-resolving factors. Targeting microglia may thus be a viable strategy to mitigate the development of POCD, particularly in those with increased vulnerability.

Combination of aspirin with essential fatty acids is superior to aspirin alone to prevent or ameliorate sepsis or ARDS

It has been suggested that aspirin may be of benefit in treating sepsis and ARDS in view of its ability to block cyclo-oxygenase-1 (COX-1) and COX-2 activities; inhibit nuclear factor kappa B (NF-κB); enhance the production of endothelial nitric oxide (eNO) and lipoxin A4 (LXA4). Our previous studies revealed that plasma phospholipid content of arachidonic acid (AA) and eicosapentaenoic acid (EPA) is low in patients with sepsis. This implies that beneficial actions of aspirin in sepsis and ARDS is unlikely to be obtained in view of deficiency of AA and EPA, the precursors of LXA4 and resolvins respectively that are potent anti-inflammatory compounds and enhancers of eNO generation. In view of this, I propose that a combination of aspirin and AA and EPA (and possibly, docosahexaenoic acid, DHA) is likely to be superior in the management of sepsis and ARDS compared to aspirin alone. This suggestion is supported by the recent observation that trauma patients with uncomplicated recoveries had higher resolvin pathway gene expression and lower gene expression ratios of leukotriene: resolvin pathways.

Obesity and post-operative cognitive dysfunction: a systematic review and meta-analysis

BACKGROUND

Post-operative cognitive dysfunction, a condition distinct from post-operative delirium (POD), occurs frequently after surgery, and is related to dementia and premature death. Obesity increases the risk of late-life cognitive impairment, but little is known about its role in post-operative cognitive dysfunction. We conducted a systematic review and meta-analysis of studies on the association between obesity and risk of post-operative cognitive dysfunction.

METHODS

PubMed and the Cochrane Library were systematically searched. Studies were included if they had prospective designs, reported on human adults undergoing surgery, if cognitive function was measured pre- and post-surgery, if obesity, body mass index (BMI) and/or body weight were ascertained, and if associations with post-operative cognitive dysfunction were reported as relative risks or odds ratios. Underweight, weight loss, and post-operative delirium were not considered.

RESULTS

Inclusion criteria were met by six articles. Samples totaled 1432 older patients (mean age ≥62 years) who were followed up for 24 h to 12 months after surgery. Analysis of studies with obesity defined as a categorical measure found a non-significantly higher risk of post-operative cognitive dysfunction among persons with BMI > 30 kg/m(2) versus ≤30 kg/m(2) (relative risk 1.27; 95% confidence interval 0.95, 1.70; p = 0.10). No such associations were found for studies that analysed BMI or body weight continuously as predictors of post-operative cognitive dysfunction (relative risk 0.98 per kg/m(2) ; 95% confidence interval 0.93, 1.03, p = 0.45; relative risk 0.99 per kg; 95% confidence interval 0.89, 1.09; p = 0.83, respectively).

CONCLUSIONS

Few studies have addressed the topic, and the results of these studies provide only limited support for an increased risk of post-operative cognitive dysfunction in patients who are obese. Further large-scale, prospective investigations are necessary for clarification. Copyright © 2016 John Wiley & Sons, Ltd.

Neural Control of Inflammation: Implications for Perioperative and Critical Care

Inflammation and immunity are regulated by neural reflexes. Recent basic science research has demonstrated that a neural reflex, termed the inflammatory reflex, modulates systemic and regional inflammation in a multiplicity of clinical conditions encountered in perioperative medicine and critical care. In this review, the authors describe the anatomic and physiologic basis of the inflammatory reflex and review the evidence implicating this pathway in the modulation of sepsis, ventilator-induced lung injury, postoperative cognitive dysfunction, myocardial ischemia-reperfusion injury, and traumatic hemorrhage. The authors conclude with a discussion of how these new insights might spawn novel therapeutic strategies for the treatment of inflammatory diseases in the context of perioperative and critical care medicine.

Effect of Ulinastatin in the Treatment of Postperative Cognitive Dysfunction: Review of Current Literature

Background. Ulinastatin, identified as a urinary trypsin inhibitor, has been widely used in patients with inflammatory disorders. However, little is known about its effect on postoperative cognitive dysfunction (POCD). The aim of our current work is to review the current body of literature. Methods. A systematic literature search in PubMed and EMBASE was performed to identify randomized controlled trials. Incidence of POCD, MMSE score, and laboratory indicators (IL-6, TNF-α, CRP, and S100β) were selected as outcomes. Results. Five RCTs involving 461 elderly patients that underwent surgical operations were identified. The meta-analysis suggested no statistical difference of incidence of POCD between ulinastatin and control groups on postoperative day 1; but ulinastatin could significantly decrease the incidence of POCD on postoperative day 3 and day 7 when compared with control treatment. Ulinastatin was effective in improving the MMSE score on day 1, day 3, and day 7 after operation. IL-6 and S100β concentrations were lower up to postoperative day 2. The incidences of postoperative complications in ulinastatin groups were lower than control. Conclusion. Ulinastatin administration was effective in treating early POCD (postoperative day 3 and day 7) and reducing IL-6 and S100β concentrations within two days after operations. Studies with larger-scale and rigorous design are urgently needed.

Postoperative cognitive dysfunction and neuroinflammation; Cardiac surgery and abdominal surgery are not the same

Postoperative cognitive dysfunction (POCD) is a debilitating surgical complication, with cardiac surgery patients at particular risk. To gain insight in the mechanisms underlying the higher incidence of POCD after cardiac versus non-cardiac surgery, systemic and central inflammatory changes, alterations in intraneuronal pathways, and cognitive performance were studied after cardiac and abdominal surgery in rats. Male Wistar rats were subjected to ischemia reperfusion of the upper mesenteric artery (abdominal surgery) or the left coronary artery (cardiac surgery). Control rats remained naïve, received anesthesia only, or received thoracic sham surgery. Rats were subjected to affective and cognitive behavioral tests in postoperative week 2. Plasma concentrations of inflammatory factors, and markers for neuroinflammation (NGAL and microglial activity) and the BDNF pathway (BDNF, p38MAPK and DCX) were determined. Spatial memory was impaired after both abdominal and cardiac surgery, but only cardiac surgery impaired spatial learning and object recognition. While all surgical procedures elicited a pronounced acute systemic inflammatory response, NGAL and TNFα levels were particularly increased after abdominal surgery. Conversely, NGAL in plasma and the paraventricular nucleus of the hypothalamus and microglial activity in hippocampus and prefrontal cortex on postoperative day 14 were increased after cardiac, but not abdominal surgery. Both surgery types induced hippocampal alterations in BDNF signaling. These results suggest that POCD after cardiac surgery, compared to non-cardiac surgery, affects different cognitive domains and hence may be more extended rather than more severe. Moreover, while abdominal surgery effects seem limited to hippocampal brain regions, cardiac surgery seems associated with more wide spread alterations in the brain.

Inflammatory bowel disease as a disorder of an imbalance between pro- and anti-inflammatory molecules and deficiency of resolution bioactive lipids

The inflammatory process seen in inflammatory bowel disease (IBD) is due to excess production of pro-inflammatory cytokines interleukin-1 (IL-1), IL-6, tumor necrosis factor-α (TNF-α), interferons (IFNs), macrophage migration inhibitory factor (MIF), HMGB1 (high mobility group B1) and possibly, a reduction in anti-inflammatory cytokines IL-10, IL-4, and transforming growth factor-β (TGF-β). These pro-inflammatory molecules lead to increased production of reactive oxygen species (ROS) including nitric oxide resulting in target tissue damage. I propose that inadequate production of inflammation resolving molecules lipoxins, resolvins, protectins, maresins and nitrolipids that suppress inflammation, ROS production, enhance wound healing and have cytoprotective properties results in inappropriate inflammation, delay in healing/repair process and so target tissue/organ damage continues in IBD. Hence, suggested therapeutic approach could include administration of stable synthetic analogues of lipoxins, resolvins, protectins, maresins and nitrolipids. This implies that measuring urine, stool and plasma levels of lipoxins, resolvins, protectins, maresins and nitrolipids may be used to detect the onset, progression and response to treatment of IBD.

The α7-nicotinic receptor is upregulated in immune cells from HIV-seropositive women: consequences to the cholinergic anti-inflammatory response

Antiretroviral therapy partially restores the immune system and markedly increases life expectancy of HIV-infected patients. However, antiretroviral therapy does not restore full health. These patients suffer from poorly understood chronic inflammation that causes a number of AIDS and non-AIDS complications. Here we show that chronic inflammation in HIV+ patients may be due to the disruption of the cholinergic anti-inflammatory pathway by HIV envelope protein gp120_IIIB. Our results demonstrate that HIV gp120_IIIB induces α7 nicotinic acetylcholine receptor (α7) upregulation and a paradoxical proinflammatory phenotype in macrophages, as activation of the upregulated α7 is no longer capable of inhibiting the release of proinflammatory cytokines. Our results demonstrate that disruption of the cholinergic-mediated anti-inflammatory response can result from an HIV protein. Collectively, these findings suggest that HIV tampering with a natural strategy to control inflammation could contribute to a crucial, unresolved problem of HIV infection: chronic inflammation.

Inverse Relationship between Serum Lipoxin A4 Level and the Risk of Metabolic Syndrome in a Middle-Aged Chinese Population

Metabolic syndrome (MetS) has been identified to be associated with a state of chronic, low-grade inflammation in adipose tissue. Lipoxins are endogenously generated from arachidonic acid, and exhibit anti-inflammatory actions. Currently, there is no available cohort study identifying the association between serum lipoxins level and MetS. Here we investigate the relationship between serum lipoxin A4 (LXA4) level and the risk of incident MetS in a middle-aged Chinese population. A total 624 participants aged 40–65 years were enrolled at baseline, with 417 (including 333 MetS absence) of them were followed up at 2.5 years. Abdominal visceral fat area (VFA) and abdominal subcutaneous fat area (SFA) were determined using MRI. Serum lipoxin A4 levels were measured by ELISA. At baseline, serum LXA4 levels were significantly correlated with a cluster of traditional MetS risk factors related to obesity (P≤0.05). A higher incidence of new Mets was found in the participants of the lowest tertile of LXA4 levels as compared with that in participants of the highest tertile (P = 0.025). Low serum LXA4 levels [OR 2.607(1.151–5.909), P = 0.022] and high VFA [OR 2.571(1.176–5.620), P = 0.018] were associated with an increased incident Mets, respectively, which remained statistically significant after adjustment for age, gender, current smoking, and alcohol drinking status. Logistic regression analysis suggested a combination of low serum LXA4 levels and high WC/VFA might optimize the prediction of incident Mets in middle-aged Chinese population [OR 4.897/4.967, P = 0.009/0.003]. Decrease in serum LXA4 level and increase in VFA are independent predictors of incident Mets in a population-based cohort, and a combination of them enhances the prognostic value of incident Mets. Taken together, our data suggest that serum LXA4 levels might be useful for early detection and prevention of Mets.

Relation between acute and long-term cognitive decline after surgery: Influence of metabolic syndrome

INTRODUCTION

The relationship between persistent postoperative cognitive decline and the more common acute variety remains unknown; using data acquired in preclinical studies of postoperative cognitive decline we attempted to characterize this relationship.

METHODS

Low capacity runner (LCR) rats, which have all the features of the metabolic syndrome, were compared postoperatively with high capacity runner (HCR) rats for memory, assessed by trace fear conditioning (TFC) on the 7th postoperative day, and learning and memory (probe trial [PT]) assessed by the Morris water-maze (MWM) at 3 months postoperatively. Rate of learning (AL) data from the MWM test, were estimated by non-linear mixed effects modeling. The individual rat's TFC result at postoperative day (POD) 7 was correlated with its AL and PT from the MWM data sets at postoperative day POD 90.

RESULTS

A single exponential decay model best described AL in the MWM with LCR and surgery (LCR-SURG) being the only significant covariates; first order AL rate constant was 0.07 s(-1) in LCR-SURG and 0.16s(-1) in the remaining groups (p<0.05). TFC was significantly correlated with both AL (R=0.74; p<0.0001) and PT (R=0.49; p<0.01).

CONCLUSION

Severity of memory decline at 1 week after surgery presaged long-lasting deteriorations in learning and memory.

Postoperative Cognitive Dysfunction: Minding the Gaps in Our Knowledge of a Common Postoperative Complication in the Elderly

Postoperative cognitive dysfunction (POCD) is a common complication associated with significant morbidity and mortality in elderly patients. There is much interest in and controversy about POCD, reflected partly in the increasing number of articles published on POCD recently. Recent work suggests surgery may also be associated with cognitive improvement in some patients, termed postoperative cognitive improvement (POCI). As the number of surgeries performed worldwide approaches 250 million per year, optimizing postoperative cognitive function and preventing/treating POCD are major public health issues. In this article, we review the literature on POCD and POCI, and discuss current research challenges in this area.

Exaggerated Acute Lung Injury and Impaired Antibacterial Defenses During Staphylococcus aureus Infection in Rats with the Metabolic Syndrome

Rats with Metabolic Syndrome (MetaS) have a dysregulated immune response to the aseptic trauma of surgery. We hypothesized that rats with MetaS would have dysregulated inflammation, increased lung injury, and less effective antibacterial defenses during Staphylococcus (S.) aureus sepsis as compared to rats without MetaS. Low capacity runner (LCR; a model of MetaS) and high capacity runner (HCR) rats were challenged intravenously with S. aureus bacteria. After 48 h, inflammatory mediators and bacteria were quantified in the blood, bronchoalveolar lavage fluid (BALF), and lung homogenates. Lungs were analyzed histologically. BALF protein and lung wet-dry ratios were quantified to assess for vascular leak. Endpoints were compared in infected LCR vs HCR rats. LCR rats had higher blood and lung S. aureus counts, as well as higher levels of IL-6 in plasma, lungs and BALF, MIP-2 in plasma and lung, and IL-17A in lungs. Conversely, LCR rats had lower levels of IL-10 in plasma and lungs. Although lactate levels, and liver and renal function tests were similar between groups, LCR rats had higher BALF protein and lung wet-dry ratios, and more pronounced acute lung injury histologically. During S. aureus bacteremia, as compared with HCR rats, LCR (MetaS) rats have heightened pro-inflammatory responses, accompanied by increased acute lung injury and vascular leak. Notably, despite an augmented pro-inflammatory phenotype, LCR rats have higher bacterial levels in their blood and lungs. The MetaS state may exacerbate lung injury and vascular leak by attenuating the inflammation-resolving response, and by weakening antimicrobial defenses.

Prior infection exacerbates postoperative cognitive dysfunction in aged rats

Older patients may experience persisting postoperative cognitive dysfunction (POCD), which is considered to largely depend on surgery-induced (neuro)inflammation. We hypothesize that inflammatory events before surgery could predispose patients to POCD. When part of our aged rats developed Mycoplasma pulmonis, this presented the unique opportunity to investigate whether a pulmonary infection before surgery influences surgery-induced neuroinflammation and POCD. Male 18-mo-old Wistar rats that had recovered from an active mycoplasma infection (infection) and control rats (healthy) were subjected to abdominal surgery and jugular vein catheterization under general anesthesia (surgery) or remained naïve (control). In postoperative week 2, behavioral tests were performed to assess cognitive performance and exploratory behavior. The acute systemic inflammatory response was investigated by measuring plasma IL-6 and IL-12. In the hippocampus, prefrontal cortex and striatum, microglial activity, neurogenesis, and concentrations of IL-6, IL-12, IL1B, and brain-derived neurotropic factor on postoperative day 14 were determined. Rats still showed signs of increased neuroinflammatory activity, as well as cognitive and behavioral changes, 3 wk after the symptoms of infection had subsided. Rats that had experienced infection before surgery exhibited a more generalized and exacerbated postoperative cognitive impairment compared with healthy surgery rats, as well as a prolonged increase in systemic cytokine levels and increased microglial activation in the hippocampus and prefrontal cortex. These findings support the hypothesis that an infection before surgery under general anesthesia exacerbates POCD. Future studies are necessary to determine whether the found effects are aging specific and to investigate the magnitude and time course of this effect in a controlled manner.

A novel regulator of lung inflammation and immunity: pulmonary parasympathetic inflammatory reflex

In this review, we first analyzed the current status of cholinergic anti-inflammatory pathway and then put forward a novel regulatory machinery-pulmonary parasympathetic inflammatory reflex, which is composed by lung vagal sensors at afferent arm, α7 nAChR (α7 nicotinic acetylcholine receptors)-expressing cells at efferent arm and the brain information integrating center. This modulatory circuit might loop the lungs, immune and nervous systems and play a very important role in regulating lung infection, inflammation and immunity through the neural innervations and signals when the lungs encounter pathogenic challenges.

Vagus nerve through α7 nAChR modulates lung infection and inflammation: models, cells, and signals

Cholinergic anti-inflammatory pathway (CAP) bridges immune and nervous systems and plays pleiotropic roles in modulating inflammation in animal models by targeting different immune, proinflammatory, epithelial, endothelial, stem, and progenitor cells and signaling pathways. Acute lung injury (ALI) is a devastating inflammatory disease. It is pathogenically heterogeneous and involves many cells and signaling pathways. Here, we emphasized the research regarding the modulatory effects of CAP on animal models, cell population, and signaling pathways that involved in the pathogenesis of ALI. By comparing the differential effects of CAP on systemic and pulmonary inflammation, we postulated that a pulmonary parasympathetic inflammatory reflex is formed to sense and respond to pathogens in the lung. Work targeting the formation and function of pulmonary parasympathetic inflammatory reflex would extend our understanding of how vagus nerve senses, recognizes, and fights with pathogens and inflammatory responses.

High-mobility group box 1 protein initiates postoperative cognitive decline by engaging bone marrow-derived macrophages

BACKGROUND

Aseptic trauma engages the innate immune response to trigger a neuroinflammatory reaction that results in postoperative cognitive decline. The authors sought to determine whether high-mobility group box 1 protein (HMGB1), an ubiquitous nucleosomal protein, initiates this process through activation and trafficking of circulating bone marrow-derived macrophages to the brain.

METHODS

The effects of HMGB1 on memory (using trace fear conditioning) were tested in adult C57BL/6J male mice; separate cohorts were tested after bone marrow-derived macrophages were depleted by clodrolip. The effect of anti-HMGB1 neutralizing antibody on the inflammatory and behavioral responses to tibial surgery were investigated.

RESULTS

A single injection of HMGB1 caused memory decline, as evidenced by a decrease in freezing time (52 ± 11% vs. 39 ± 5%; n = 16-17); memory decline was prevented when bone marrow-derived macrophages were depleted (39 ± 5% vs. 50 ± 9%; n = 17). Disabling HMGB1 with a blocking monoclonal antibody, before surgery, reduced postoperative memory decline (52 ± 11% vs. 29 ± 5%; n = 15-16); also, hippocampal expression of monocyte chemotactic protein-1 was prevented by the neutralizing antibody (n = 6). Neither the systemic nor the hippocampal inflammatory responses to surgery occurred in mice pretreated with anti-HMGB1 neutralizing antibody (n = 6).

CONCLUSION

Postoperative neuroinflammation and cognitive decline can be prevented by abrogating the effects of HMGB1. Following the earlier characterization of the resolution of surgery-induced memory decline, the mechanisms of its initiation are now described. Together, these data may be used to preoperatively test the risk to surgical patients for the development of exaggerated and prolonged postoperative memory decline that is reflected in delirium and postoperative cognitive dysfunction, respectively.

Detection of impaired cognitive function in rat with hepatosteatosis model and improving effect of GLP-1 analogs (exenatide) on cognitive function in hepatosteatosis

The aims of the study were to evaluate (1) detection of cognitive function changing in rat with hepatosteatosis model and (2) evaluate the effect of GLP-1 analog (exenatide) on cognitive function in hepatosteatosis. In the study group, 30% fructose was given in nutrition water to perform hepatosteatosis for 8 weeks to 18 male rats. Six male rats were chosen as control group and had normal nutrition. Fructose nutrition group were stratified into 3 groups. In first group (n = 6), intracerebroventricular (ICV) infusion of exenatide (n = 6) was given. ICV infusion of NaCl (n = 6) was given to second group. And also, the third group had no treatment. And also, rats were evaluated for passive avoidance learning (PAL) and liver histopathology. Mean levels of latency time were statistically significantly decreased in rats with hepatosteatosis than those of normal rats (P < 0.00001). However, mean level of latency time in rats with hepatosteatosis treated with ICV exenatide was statistically significantly increased than that of rats treated with ICV NaCl (P < 0.001). Memory performance falls off in rats with hepatosteatosis feeding on fructose (decreased latency time). However, GLP-1 ameliorates cognitive functions (increased latency time) in rats with hepatosteatosis and releated metabolic syndrome.

High inborn aerobic capacity does not protect the heart following myocardial infarction

Maximal oxygen uptake (Vo2max) is a strong prognostic marker for morbidity and mortality, but the cardio-protective effect of high inborn Vo2max remains unresolved. We aimed to investigate whether rats with high inborn Vo2max yield cardio-protection after myocardial infarction (MI) compared with rats with low inborn Vo2max. Rats breed for high capacity of running (HCR) or low capacity of running (LCR) were randomized into HCR-SH (sham), HCR-MI, LCR-SH, and LCR-MI. Vo2max was lower in HCR-MI and LCR-MI compared with respective sham (P < 0.01), supported by a loss in global cardiac function, assessed by echocardiography. Fura 2-AM loaded cardiomyocyte experiments revealed that HCR-MI and LCR-MI decreased cardiomyocyte shortening (39%, and 34% reduction, respectively, both P < 0.01), lowered Ca(2+) transient amplitude (37%, P < 0.01, and 20% reduction, respectively), and reduced sarcoplasmic reticulum (SR) Ca(2+) content (both; 20%, P < 0.01) compared with respective sham. Diastolic Ca(2+) cycling was impaired in HCR-MI and LCR-MI evidenced by prolonged time to 50% Ca(2+) decay that was partly explained by the 47% (P < 0.01) and 44% (P < 0.05) decrease in SR Ca(2+)-ATPase Ca(2+) removal, respectively. SR Ca(2+) leak increased by 177% in HCR-MI (P < 0.01) and 67% in LCR-MI (P < 0.01), which was abolished by inhibition of Ca(2+)/calmodulin-dependent protein kinase II. This study demonstrates that the effect of MI in HCR rats was similar or even more pronounced on cardiac- and cardiomyocyte contractile function, as well as on Ca(2+) handling properties compared with observations in LCR. Thus our data do not support a cardio-protective effect of higher inborn aerobic capacity.