Association Between Inflammatory Markers and Cognitive Outcome in Patients with Acute Brain Dysfunction Due to Sepsis

Clinical value of serum neuron-specific enolase in sepsis-associated encephalopathy: a systematic review and meta-analysis

OBJECTIVE

This study aimed to investigate the serum levels of neuron-specific enolase (NSE) in sepsis-associated encephalopathy (SAE) and perform a meta-analysis to assess the diagnostic and prognostic potential of serum NSE in SAE patients.

METHODS

We searched English and Chinese databases for studies related to SAE that reported serum NSE levels until November 2023. We extracted information from these studies including the first author and year of publication, the number of samples, the gender and age of patients, the collection time of blood samples in patients, the assay method of serum NSE, the study methods, and the levels of serum NSE with units of ng/mL. The quality assessment of diagnostic accuracy studies 2 (QUADAS-2) tool was used to evaluate the study quality. A meta-analysis was performed using Review Manager version 5.3, employing either a random effects model or a fixed effects model.

RESULTS

A total of 17 studies were included in the final meta-analysis, including 682 SAE patients and 946 NE patients. The meta-analysis demonstrated significantly higher serum NSE levels in SAE patients compared to NE patients (Z = 5.97, P < 0.001, MD = 7.79, 95%CI 5.23-10.34), irrespective of the method used for serum NSE detection (Z = 6.15, P < 0.001, mean difference [MD] = 7.75, 95%CI 5.28-10.22) and the study methods (Z = 5.97, P < 0.001, MD = 7.79, 95%CI 5.23-10.34). Furthermore, sepsis patients with a favorable outcome showed significantly lower levels of serum NSE compared to those with an unfavorable outcome (death or adverse neurological outcomes) (Z = 5.44, P < 0.001, MD = - 5.34, 95%CI - 7.26-3.42).

CONCLUSION

The Serum level of NSE in SAE patients was significantly higher than that in septic patients without encephalopathy. The higher the serum NSE level in SAE patients, the higher their mortality rate and incidence of adverse neurological outcomes.

Combining biomarkers of BNIP3 L, S100B, NSE, and accessible measures to predict sepsis-associated encephalopathy: a prospective observational study

BACKGROUND

Accurate identification of delirium in sepsis patients is crucial for guiding clinical diagnosis and treatment. However, there are no accurate biomarkers and indicators at present. We aimed to identify which combinations of cognitive impairment-related biomarkers and other easily accessible assessments best predict delirium in sepsis patients.

METHODS

One hundred and one sepsis patients were enrolled in a prospective study cohort. S100B, NSE, and BNIP3 L biomarkers were detected in plasma and cerebrospinal fluid and patients' optic nerve sheath diameter (ONSD). The optimal biomarkers identified by Logistic regression are combined with other factors such as ONSD to filter out the perfect model to predict delirium in sepsis patients through Logistic regression, Naïve Bayes, decision tree, and neural network models.

MAIN RESULTS

Among all biomarkers, compared with BNIP3 L (AUC = .706, 95% CI = .597-.815) and NSE (AUC = .711, 95% CI = .609-.813) in cerebrospinal fluid, plasma S100B (AUC = .729, 95% CI = .626-.832) had the best discrimination performance for delirium in sepsis patients. Logistic regression analysis showed that the combination of cerebrospinal fluid BNIP3 L with plasma S100B, ONSD, neutrophils, and age provided the best discrimination to cognitive impairment in sepsis patients (accuracy = .901, specificity = .923, sensitivity = .911), which was better than Naïve Bayes, decision tree, and neural network models. Neutrophils, ONSD, and cerebrospinal fluid BNIP3 L were consistently the major contributors in a few models.

CONCLUSIONS

The logistic regression showed that the combination model was strongly correlated with cognitive dysfunction in sepsis patients.

Use of the MicroSiM (µSiM) Barrier Tissue Platform for Modeling the Blood-Brain Barrier

The microSiM (µSiM) is a membrane-based culture platform for modeling the blood-brain barrier (BBB). Unlike conventional membrane-based platforms, the µSiM provides experimentalists with new capabilities, including live cell imaging, unhindered paracrine signaling between 'blood' and 'brain' chambers, and the ability to directly image immunofluorescence without the need for the extraction/remounting of membranes. Here we demonstrate the basic use of the platform to establish monoculture (endothelial cells) and co-culture (endothelial cells and pericytes) models of the BBB using ultrathin nanoporous silicon-nitride membranes. We demonstrate compatibility with both primary cell cultures and human induced pluripotent stem cell (hiPSC) cultures. We provide methods for qualitative analysis of BBB models via immunofluorescence staining and demonstrate the use of the µSiM for the quantitative assessment of barrier function in a small molecule permeability assay. The methods provided should enable users to establish their barrier models on the platform, advancing the use of tissue chip technology for studying human tissues.

Septic encephalopathy in the elderly - biomarkers of potential clinical utility

Next to acute sickness behavior, septic encephalopathy is the most frequent involvement of the brain during infection. It is characterized by a cross-talk of pro-inflammatory cells across the blood-brain barrier, by microglial activation and leukocyte migration, but not by the entry of infecting organisms into the brain tissue. Septic encephalopathy is very frequent in older persons because of their limited cognitive reserve. The predominant clinical manifestation is delirium, whereas focal neurological signs and symptoms are absent. Electroencephalography is a very sensitive method to detect functional abnormalities, but these abnormalities are not specific for septic encephalopathy and of limited prognostic value. Routine cerebral imaging by computer tomography usually fails to visualize the subtle abnormalities produced by septic involvement of the brain. Magnetic resonance imaging is by far more sensitive to detect vasogenic edema, diffuse axonal injury or small ischemic lesions. Routine laboratory parameters most suitable to monitor sepsis, but not specific for septic encephalopathy, are C-reactive protein and procalcitonin. The additional measurement of interleukin (IL)-6, IL-8, IL-10 and tumor necrosis factor-α increases the accuracy to predict delirium and an unfavorable outcome. The most promising laboratory parameters to quantify neuronal and axonal injury caused by septic encephalopathy are neurofilament light chains (NfL) and S100B protein. Neuron-specific enolase (NSE) plasma concentrations are strongly influenced by hemolysis. We propose to determine NSE only in non-hemolytic plasma or serum samples for the estimation of outcome in septic encephalopathy.

Correlation between neutrophil/lymphocyte ratio, platelet/lymphocyte ratio and postoperative cognitive dysfunction in elderly patients with esophageal cancer

The present study intends to investigate the correlation between neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR) and postoperative cognitive dysfunction (POCD) in elderly patients with esophageal cancer. Elderly patients >65 years old with esophageal cancer in our department from October 2017 to June 2021 were included in the study. The cognitive function of the patients was assessed by the mini-mental state examination (MMSE) Scale at 1day, 3 days, and 7days after surgery. POCD was considered when the scores were <27 points, and the remaining patients were included in the control group. A total of 104 elderly patients with esophageal cancer were included in this study, and 24 patients developed POCD, with an incidence of 23.1%. The expression of NLR and PLR in both 2 groups was increased on the 1st postoperative day compared with that before surgery. There was no significant difference in the expression of NLR and PLR between the 2 groups before operation, but the expression of both in the POCD group was significantly higher than that in the control group after operation (P < .05). Logistic regression analysis showed that smoking, postoperative NLR and postoperative PLR were independent risk factors for POCD. Spearman test showed that NLR was negatively correlated with MMSE scores at postoperative 1 day and 3 days (P < .05), while PLR was negatively correlated with MMSE scores at postoperative 1 day, 3 days and 7 days (P < .05). The Area Under receiver operating characteristic curve (AUC) of postoperative NLR for predicting POCD in elderly patients with esophageal cancer was 0.656, and the AUC of postoperative PLR was 0.722. After combination of NLR and PLR, the AUC increased to 0.803 with the sensitivity of 66.7% and specificity of 82.5%. The expression level of postoperative NLR and PLR in elderly patients with esophageal cancer combined with POCD is significantly increased, which is associated with postoperative cognitive impairment. Moreover, the combination of NLR and PLR has a good predictive ability for POCD, which could be used as a potential biomarker for early diagnosis of POCD.

What's new on septic encephalopathy? Ten things you need to know

Sepsis associated encephalopathy (SAE) is a frequent complication of sepsis and is associated with a higher risk of short-term mortality and long-term cognitive impairment. The EEG is a sensitive complement of the clinical examination that can also detect and quantify encephalopathy and identify features with prognostic value, such as lack of reactivity. Moreover, despite their effect on outcome is still debated, the EEG is the only tool to detect non-convulsive seizures which can occur in a septic setting. Understanding the pathophysiology of SAE is fundamental to define potential therapeutic targets. Neuroinflammation plays an important role in the development of SAE and many blood and imaging biomarkers have recently shown a promising ability to distinguish SAE form non-SAE patient. In recent years, some interesting mediators of inflammation were successfully targeted in animal models, with a significant reduction in the neuroinflammation and in sepsis-induced cognitive decline. However, the complexity of the host response to sepsis currently limits the use of immunomodulation therapies in humans. Alteration in regulatory systems of cerebral blood flow, namely cerebral autoregulation (CA) and neurovascular coupling, contribute to SAE development. Nowadays, clinicians have access to different tools to assess them at the bedside and CA-based blood pressure protocols should be implemented to optimize cerebral perfusion. Its inauspicious consequences, its complex physiopathology and the lack of efficacious treatment make of SAE a highly active research subject.

Cerebral Blood Flow Alterations in Sepsis-Associated Encephalopathy: A Prospective Observational Study

BACKGROUND

The timely recognition of sepsis-associated encephalopathy (SAE) remains a challenge. This study aimed to observe the CBF changes via TCD during sepsis and explore their possible predictive value in SAE.

METHODS

In this prospective observational study, septic patients were enrolled and classified according to the diagnosis of SAE into two groups: SAE group and non-SAE group. Then SAE patients were further divided into subgroup A (the type with agitation) and subgroup B (the type with depressed consciousness) based on their clinical manifestations. The clinical profiles and TCD parameters within 24 hours of onset were compared between groups and subgroups.

RESULTS

Exactly 198 septic patients were enrolled including 65 patients in SAE group (36 male/29 female with a median age of 70) and 133 patients in non-SAE group (75 male/58 female with a median age of 67). Significant elevated peak-systolic velocity (VS; 107 [69-138] cm/s vs 85 [69-101] cm/s, P = .002) of the left middle cerebral artery (MCA) and pulsatility index (PI; left: 0.99 [0.81-1.34] vs 0.89 [0.76-1.00], P < .001; right: 0.99 [0.77-1.21] vs 0.88 [0.78-1.03], P = .007) of bilateral MCAs were found in SAE group compared with non-SAE group. In subgroup analysis, subgroup A (the type with agitation) showed significantly increased VS/VM/VD and lower PI/RI of bilateral MCAs compared with subgroup B (the type with depressed consciousness). The cerebral blood flow volume of subgroup A were obviously higher than subgroup B [858.7 (729.1,876.9) mL/s vs 380.9 (373.3,447.4) mL/s, P < .001].

CONCLUSIONS

This study confirmed the abnormal CBF among SAE and found different types of CBF alterations were related to different clinical features. VS and PI might help clinicians to early identify different types of SAE.

Complement and Coagulation System Crosstalk in Synaptic and Neural Conduction in the Central and Peripheral Nervous Systems

Complement and coagulation are both key systems that defend the body from harm. They share multiple features and are similarly activated. They each play individual roles in the systemic circulation in physiology and pathophysiology, with significant crosstalk between them. Components from both systems are mapped to important structures in the central nervous system (CNS) and peripheral nervous system (PNS). Complement and coagulation participate in critical functions in neuronal development and synaptic plasticity. During pathophysiological states, complement and coagulation factors are upregulated and can modulate synaptic transmission and neuronal conduction. This review summarizes the current evidence regarding the roles of the complement system and the coagulation cascade in the CNS and PNS. Possible crosstalk between the two systems regarding neuroinflammatory-related effects on synaptic transmission and neuronal conduction is explored. Novel treatment based on the modulation of crosstalk between complement and coagulation may perhaps help to alleviate neuroinflammatory effects in diseased states of the CNS and PNS.

Sepsis and Cognitive Assessment

Sepsis disproportionally affects people over the age of 65, and with an exponentially increasing older population, sepsis poses additional risks for cognitive decline. This review summarizes published literature for (1) authorship qualification; (2) the type of cognitive domains most often assessed; (3) timelines for cognitive assessment; (4) the control group and analysis approach, and (5) sociodemographic reporting. Using key terms, a PubMed database review from January 2000 to January 2021 identified 3050 articles, and 234 qualified as full text reviews with 18 ultimately retained as summaries. More than half (61%) included an author with an expert in cognitive assessment. Seven (39%) relied on cognitive screening tools for assessment with the remaining using a combination of standard neuropsychological measures. Cognitive domains typically assessed were declarative memory, attention and working memory, processing speed, and executive function. Analytically, 35% reported on education, and 17% included baseline (pre-sepsis) data. Eight (44%) included a non-sepsis peer group. No study considered sex or race/diversity in the statistical model, and only five studies reported on race/ethnicity, with Caucasians making up the majority (74%). Of the articles with neuropsychological measures, researchers report acute with cognitive improvement over time for sepsis survivors. The findings suggest avenues for future study designs.

Neuroinflammation in Sepsis: Molecular Pathways of Microglia Activation

Frequently underestimated, encephalopathy or delirium are common neurological manifestations associated with sepsis. Brain dysfunction occurs in up to 80% of cases and is directly associated with increased mortality and long-term neurocognitive consequences. Although the central nervous system (CNS) has been classically viewed as an immune-privileged system, neuroinflammation is emerging as a central mechanism of brain dysfunction in sepsis. Microglial cells are major players in this setting. Here, we aimed to discuss the current knowledge on how the brain is affected by peripheral immune activation in sepsis and the role of microglia in these processes. This review focused on the molecular pathways of microglial activity in sepsis, its regulatory mechanisms, and their interaction with other CNS cells, especially with neuronal cells and circuits.

Brain Volume Changes in Patients with Acute Brain Dysfunction Due to Sepsis

BACKGROUND

Sepsis-induced brain dysfunction (SIBD) is often encountered in sepsis patients and is related to increased morbidity. No specific tests are available for SIBD, and neuroimaging findings are often normal. In this study, our aim was to analyze the diagnostic value of volumetric analysis of the brain structures and to find out its significance as a prognostic measure.

METHODS

In this prospective observational study, brain magnetic resonance imaging (MRI) sections of 25 consecutively enrolled SIBD patients (17 with encephalopathy and 8 with coma) and 22 healthy controls underwent volumetric evaluation by an automated segmentation method.

RESULTS

Ten SIBD patients had normal MRI, and 15 patients showed brain lesions or atrophy. The most prominent volume reduction was found in cerebral and cerebellar white matter, cerebral cortex, hippocampus, and amygdala, whereas deep gray matter regions and cerebellar cortex were relatively less affected. SIBD patients with normal MRI showed significantly reduced volumes in hippocampus and cerebral white matter. Caudate nuclei, putamen, and thalamus showed lower volume values in non-survivor SIBD patients, and left putamen and right thalamus showed a more pronounced volume reduction in coma patients.

CONCLUSIONS

Volumetric analysis of the brain appears to be a sensitive measure of volumetric changes in SIBD. Volume reduction in specific deep gray matter regions might be an indicator of unfavorable outcome.

Amitriptyline Reduces Sepsis-Induced Brain Damage Through TrkA Signaling Pathway

Sepsis can induce acute and chronic changes in the central nervous system termed sepsis-associated encephalopathy (SAE). Not only cognitive deficits but also anxiety, depression, and post-traumatic stress disorder are common in severe sepsis survivors. In this study, we demonstrated that amitriptyline, a classic tricyclic antidepressant, reduced sepsis-induced brain damage through the tropomyosin receptor kinase A (TrkA) signaling pathway. Amitriptyline ameliorated neuronal loss assessed by Nissl staining in a mouse cecal ligation and puncture (CLP)-induced sepsis model. Furthermore, amitriptyline reduced early gliosis assessed by immunofluorescence and late cognitive deficits assessed by the Morris water maze (MWM) test. Moreover, amitriptyline treatment attenuated oxidative stress indicated by less superoxide dismutase (SOD) and catalase (CAT) activity consumption and malondialdehyde (MDA) accumulation. Interestingly, those protective effects of amitriptyline could be abolished by GW441756, a TrkA signaling pathway inhibitor. Immunoblot directly showed that TrkA signaling pathway-associated proteins, such as Akt and GSK3β, were involved in the neuroprotective effects of amitriptyline. Thus, amitriptyline appears to be an encouraging candidate to treat cognitive deficits and depression after severe sepsis.

Staphylococcus epidermidis Sensitizes Perinatal Hypoxic-Ischemic Brain Injury in Male but Not Female Mice

Background: Staphylococcus epidermidis is the most common nosocomial infection and the predominant pathogen in late-onset sepsis in preterm infants. Infection and inflammation are linked to neurological and developmental sequelae and bacterial infections increase the vulnerability of the brain to hypoxia-ischemia (HI). We thus tested the hypothesis that S. epidermidis exacerbates HI neuropathology in neonatal mice. Methods: Male and female C57Bl/6 mice were injected intraperitoneally with sterile saline or 3.5 × 10⁷ colony-forming units of S. epidermidis on postnatal day (PND) 4 and then subjected to HI on PND5 (24 h after injection) or PND9 (5 d after injection) by left carotid artery ligation and exposure to 10% O₂. White and gray matter injury was assessed on PND14-16. In an additional group of animals, the plasma, brain, and liver were collected on PND5 or PND9 after infection to evaluate cytokine and chemokine profiles, C5a levels and C5 signaling. Results: HI induced 24 h after injection of S. epidermidis resulted in greater gray and white matter injury compared to saline injected controls in males, but not in females. Specifically, males demonstrated increased gray matter injury in the cortex and striatum, and white matter loss in the subcortical region, hippocampal fimbria and striatum. In contrast, there was no potentiation of brain injury when HI occurred 5 d after infection in either sex. In the plasma, S. epidermidis-injected mice demonstrated increased levels of pro- and anti-inflammatory cytokines and chemokines and a reduction of C5a at 24 h, but not 5 d after infection. Brain CCL2 levels were increased in both sexes 24 h after infection, but increased only in males at 5 d post infection. Conclusion: Ongoing S. epidermidis infection combined with neonatal HI increases the vulnerability of the developing brain in male but not in female mice. These sex-dependent effects were to a large extent independent of expression of systemic cytokines or brain CCL2 expression. Overall, we provide new insights into how systemic S. epidermidis infection affects the developing brain and show that the time interval between infection and HI is a critical sensitizing factor in males.

Posterior Reversible Encephalopathy Syndrome and Septic Encephalopathy: Neuroimaging, Inflammation and Neurodegeneration Findings

Posterior reversible encephalopathy syndrome (PRES) is known to be associated with septic encephalopathy. The pathophysiology of septic encephalopathy is thought to involve inflammatory immune response pathways. We are reporting a patient with septic encephalopathy and PRES with well documented inflammatory biomarkers and neuroradiological findings.

The Impact of Prophylactic Lacosamide on LPS-Induced Neuroinflammation in Aged Rats

Sepsis-induced central nervous system damage is called sepsis-associated encephalopathy (SAE). In addition to neuroinflammation, oxidative stress and apoptosis act in the development of SAE. In the current study, we evaluated the protective effects of lacosamide (LCM) on neuroinflammation induced by lipopolysaccharide (LPS). Twenty-four Wistar albino rats were divided into 3 groups as controls, LPS group (5 mg/kg i.p.), and LPS plus LCM group (5 mg/kg i.p and 40 mg/kg i.p, respectively). In the rat brain, LPS-induced tissue damage was revealed histopathologically as hyperemia and microhemorrhages. LCM pretreatment ameliorated these histopathological changes. LPS decreased brain TAS levels and significantly increased MDA, CRP, HSP, IL-1β, and TNF-α expressions in the cortex, hippocampus, and cerebellum. Western analysis revealed increased brain tissue levels of TNF-α, NF-Kβ, and caspase-3 following LPS. Prophylactic LCM treatment reversed these parameters including oxidative stress, inflammation, and apoptosis in the cortex, hippocampus, and cerebellum.

Diagnosing acute brain dysfunction due to sepsis

Developments in the management of critically ill patients suffering organ dysfunctions have demonstrated that brain is the prominent organ to be effected during critical illness. Acute brain dysfunction due to pathologic neuroinflammatory processes associated with sepsis is commonly seen and related to morbidity and mortality in the ICU treatment. Studies reported that survivors of sepsis may suffer long-term cognitive dysfunction that affects quality of life. However, there are no specific approaches to diagnose acute brain dysfunction in the early phase to target protective measures. In recent years, imaging methods and biomarkers are the most important issues of studies. This review will address the current diagnostic approaches to acute brain dysfunction related to sepsis.