Effects of S100B neutralization on the long-term cognitive impairment and neuroinflammatory response in an animal model of sepsis

Assessment of the combined utility of S100B, GFAP, and IL-6 in predicting long-term cognitive impairment in survivors of sepsis

OBJECTIVE

The main purpose of this study was to comprehensively investigate the combined utility of S100B, GFAP, and IL-6 as predictors of long-term cognitive impairment in sepsis survivors. Specifically, we aimed to determine whether these biomarkers, either individually or in combination, could effectively predict the occurrence of long-term cognitive impairment in this patient population, and to explore their potential as valuable clinical tools for early detection and intervention.

METHODS

This retrospective study enrolled 114 sepsis patients. Patients were divided into non-cognitive impairment and cognitive impairment groups. Serum biomarker levels were compared, and correlations between biomarkers and cognitive impairment were explored. ROC analysis evaluated the predictive value of S100B, GFAP, and IL-6 levels, and the combined diagnosis of the three biomarkers was studied.

RESULTS

The non-cognitive impairment group had a younger age, higher education level, employment rate, married rate, and presence of family members (p < 0.05). Correlation analysis showed positive correlations between cognitive impairment and CRP, IL-10, S100B, GFAP, and IL-6 (p < 0.05). AUC values of S100B, GFAP, and IL-6 were 0.792, 0.752, and 0.732, respectively, indicating significant predictive value for cognitive impairment. Combined prediction using the three biomarkers had an AUC value of 0.887, with a specificity of 88% and sensitivity of 89%.

CONCLUSION

Long-term cognitive impairment in sepsis survivors is influenced by various cytokines. Significant differences were found in biomarker levels between non-cognitive impairment and cognitive impairment groups. The combined utility of S100B, GFAP, and IL-6 showed significant predictive value for cognitive impairment in survivors of sepsis.

Microglial activation and neuroinflammation in acute and chronic cognitive deficits in sepsis

Sepsis is characterised by dysregulated immune responses to infection, leading to multi-organ dysfunction and high rates of mortality. With increasing survival rates in recent years long-term neurological and psychiatric consequences have become more apparent in survivors. Many patients develop sepsis associated encephalopathy (SAE) which encompasses the profound but usually transient neuropsychiatric syndrome delirium but also new brain injury that emerges in the months and years post-sepsis. It is now clear that systemic inflammatory signals reach the brain during sepsis and that very significant neuroinflammation ensues. The major brain resident immune cell population, the microglia, has been implicated in acute and chronic cognitive dysfunction in animal models of sepsis based on a growing number of studies using bacterial endotoxin and in polymicrobial sepsis models such as cecal ligation and puncture. The current review explores the effects of sepsis on the brain, focussing on how systemic insults translate to microglial activation and neuroinflammation and how this disrupts neuronal function and integrity. We examine what has been demonstrated specifically with respect to microglial activation, revealing robust evidence for a role for neuroinflammation in sepsis-induced brain sequelae but less clear information on the extent of the specific microglial contribution to this, arising from findings using global knockout mice, non-selective drugs and treatments that equally target peripheral and central compartments. There is, nonetheless, clear evidence that microglia do become activated and do contribute to brain consequences of sepsis thus arguing for improved understanding of these neuroinflammatory processes toward the prevention and treatment of sepsis-induced brain dysfunction.

1,25(OH)2D3 supplementation alleviates gut-vascular barrier disruption via inhibition of S100B/ADAM10 pathway

Gut-vascular barrier (GVB) is the second barrier in mucosa to control systemic dissemination of gut bacteria. Severe burns induce enteroglial cells to produce S100B and endothelial cells to generate ADAM10 and cause vitamin D3 insufficiency/deficiency and GVB disruption. It is not clear whether vitamin D3 supplementation attenuates GVB damage via regulation of S100B/ADAM10 pathway. Here, GVB disruption was induced by 30% of total body surface area scalds. Rats were treated with 1,25(OH)2D3 (0.05, 0.5 or 5 μg/kg) or S100B monoclonal antibody (S100BmAb, 10 μg/kg) or GI254023X (ADAM10 inhibitor, 100 mg/kg). Rat enteric glial cell-line CRL2690 and rat intestinal microvascular endothelial cells (RIMECs) were treated with S100B (5 μM) or plus 1,25(OH)2D3 (0.05, 0.5 or 5 μM) or GI254023X (5 μM). S100B, TNF-α, 25(OH)D3 and 1,25(OH)2D3 in serum and gut mucosa were determined by enzyme-linked immunosorbent assay. The endothelial permeability was measured using FITC-dextran 70 kDa. ADAM10 and β-catenin expression was assayed by Western blot. The results showed that 1,25(OH)2D3 and 25(OH)D3 concentration in serum reduced whereas TNF-α and S100B in serum and gut mucosa increased in burned rats. S100BmAb, GI254023X and 1,25(OH)2D3 treatment lowered burns-increased GVB permeability. 1,25(OH)2D3 also decreased S100B concentration in serum and gut mucosa. 1,25(OH)2D3 inhibited S100B release from TNF-α-treated CRL2690 and raised β-catenin while decreasing ADAM10 protein in S100B-treated RIMECs. 1,25(OH)2D3 and GI254023X also decreased the endothelial permeability of S100B-treated RIMECs. Collectively, these findings provide evidence that severe burns lower serum 25(OH)D3 and 1,25(OH)2D3 concentration. 1,25(OH)2D3 supplementation alleviates burns-elicited GVB disruption via inhibition of S100B/ADAM10 signaling.

Effect of high-intensity interval training on self-care and anxiety-like behaviors in naive rats

Self-care behavior covers individual's health, life and well-being to maintain the necessary activities. The aim of this study is to examine the self-care and possible anxiolytic effects of high-intensity interval exercise (HIIT). Eight-week-old Wistar Albino male rats were divided into Control (n = 8), and Exercise (n = 8). Rat exercised for 38 min a day, 5 days a week, for 8 weeks The animals were then subjected to open field test and splash test, and the behaviors were video recorded. Student t test and Shapiro-Wilk test were used as statistical tests. In the exercise group, spray-induced grooming behavior increased significantly in terms of duration and frequency (p < 0.05), but no significant difference was observed in the latency of grooming (p > 0.05). In the open-field test, the total distance traveled, which is a locomotor activity parameter, did not change between the groups. Anxiolytic-like behaviors such as total rearing behavior, unsupported rearing, central time, and central region entries increased remarkably in the exercise group vs. control (p < 0.0001). Freezing as an anxiogenic behavior decreased in the exercise group positively (p < 0.0001). Intermittent high-intensity exercise improved and increased self-care behaviors. Further, the present study shows that HIIT has beneficial effects on different aspects of behaviors such as exploratory behaviors, increasing anxiolytic behaviors, and reducing anxiogenic behavior. The present study is a preclinical study that will pave the way for new studies.

Sepsis sensitizes behavioural amphetamine responses while inducing inflammatory and neurotrophic vulnerability in the cecal ligation and puncture model

The present study aimed to evaluate if sepsis sensitizes behavioural and biochemical responses induced by m-amphetamine. For this, Wistar rats were submitted to the cecal ligation and puncture. After 30 days of cecal ligation and puncture procedure, the animals were submitted to a single intraperitoneal injection of saline or m-amphetamine (.25, .50, or 1.0 mg/kg). Locomotor behaviour was assessed 2 h after the administration. Interleukin (IL)-1β, IL-6, IL-10, tumour necrosis factor-α, dopamine-cAMP-regulated phosphoprotein of 32,000 kDa (DARPP-32) and neuronal calcium sensor (NCS-1) levels were evaluated in the frontal cortex, hippocampus and striatum. Also, brain-derived neurotrophic factor (BDNF), neuronal growth factor and glial-derived neurotrophic factor levels were assessed in the hippocampus. M-amphetamine alone (.25 and 1.0 mg/kg) increased rats' locomotion and exploratory behaviour compared with the Sham + Sal. Animals from the cecal ligation and puncture + m-amphetamine (.5 and/or 1.0 mg/kg) group showed an increase in locomotion, exploratory and risk-like behaviour when compared with the Sham + Saline group and with its respective Sham groups. Cecal ligation and puncture increased interleukin levels compared with the Sham + Sal. However, cecal ligation and puncture animals that received m-amphetamine (1 mg/kg) increased even more, these inflammatory parameters compared with the Sham + Sal and the cecal ligation and puncture + saline group. M-amphetamine at lower doses increased neurotrophic factors, but higher doses decreased these parameters in the brain of cecal ligation and puncture rats. M-amphetamine dose-dependently increased DARPP-32 and NCS-1 levels in cecal ligation and puncture rats in some structures. In conclusion, these results demonstrate that sepsis sensitizes behavioural amphetamine responses while inducing inflammatory and neurotrophic vulnerability in the cecal ligation and puncture model.

Comorbidity Genes of Alzheimer's Disease and Type 2 Diabetes Associated with Memory and Cognitive Function

Alzheimer's disease (AD) and type 2 diabetes mellitus (T2DM) are comorbidities that result from the sharing of common genes. The molecular background of comorbidities can provide clues for the development of treatment and management strategies. Here, the common genes involved in the development of the two diseases and in memory and cognitive function are reviewed. Network clustering based on protein-protein interaction network identified tightly connected gene clusters that have an impact on memory and cognition among the comorbidity genes of AD and T2DM. Genes with functional implications were intensively reviewed and relevant evidence summarized. Gene information will be useful in the discovery of biomarkers and the identification of tentative therapeutic targets for AD and T2DM.

Protective effect of omega-3 polyunsaturated fatty acids on sepsis via the AMPK/mTOR pathway

CONTEXT

Sepsis is a systemic inflammatory response caused by infection, with high morbidity and mortality. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) have reported biological activities.

OBJECTIVE

This study explored the signaling pathways through which ω-3 PUFAs protect against sepsis-induced multiorgan failure.

MATERIALS AND METHODS

Septic Sprague-Dawley (SD) rat model was established by the cecum ligation perforation (CLP) method. Rats were divided into control, sham, model, parenteral ω-3 PUFAs (0.5 g/kg) treatment, ω-3 PUFAs (0.5 g/kg) + AMPK inhibitor Compound C (30 mg/kg) treatment, and ω-3 PUFAs (0.5 g/kg) + mTOR activator MHY1485 (10 mg/kg) treatment groups. The serum inflammatory cytokines were measured using ELISA. Organ damage-related markers cTnI, CK, CK-MB, Cr, BUN, ALT, and AST were measured using an automated chemical analyzer. The AMPK/mTOR pathway in liver, kidney, and myocardial tissues was detected using western blot and qRT-PCR methods.

RESULTS

CLP treatment enhanced the secretion of pro-inflammatory cytokines and multi-organ related markers, along with increased p-AMPK/AMPK ratio (from 0.47 to 0.87) and decreased p-mTOR/mTOR ratio (from 0.33 to 0.12) in rats. The inflammation response and multi-organ injury induced by CLP treatment could be partially counteracted by 0.5 g/kg parenteral ω-3 PUFA treatment. The activated AMPK/mTOR pathway in CLP-induced rats was further promoted. Finally, Compound C and MHY1485 could reverse the effects of parenteral ω-3 PUFA treatment on sepsis rats.

DISCUSSION AND CONCLUSION

ω-3 PUFAs ameliorated sepsis development by activating the AMPK/mTOR pathway, serving as a potent therapeutic agent for sepsis. Further in vivo studies may validate potential clinical use.

Microglial Activation: Key Players in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a common brain dysfunction, which results in severe cognitive and neurological sequelae and an increased mortality rate in patients with sepsis. Depending on the stimulus, microglia (resident macrophages in the brain that are involved in SAE pathology and physiology) can adopt two polarization states (M1/M2), corresponding to altered microglial morphology, gene expression, and function. We systematically described the pathogenesis, morphology, function, and phenotype of microglial activation in SAE and demonstrated that microglia are closely related to SAE occurrence and development, and concomitant cognitive impairment. Finally, some potential therapeutic approaches that can prime microglia and neuroinflammation toward the beneficial restorative microglial phenotype in SAE were outlined.

Indole-3-carbinol mitigates oxidative stress and inhibits inflammation in rat cerebral ischemia/reperfusion model

Ischemia is a significant pathogenetic factor of stroke with very limited treatment options. The objective of our research was to evaluate the protective properties of indole-3-carbinol (I3C) and its effect on redox status parameters, inflammation, and apoptosis intensity in cerebral ischemia/reperfusion injury (CIRI) in rats. I3C administration to CIRI rats decreased levels of oxidative stress markers and improved aerobic metabolism compared to the animals with CIRI. A decrease in myeloperoxidase activity, proinflammatory cytokines mRNA levels, and expression of redox-sensitive factor Nuclear Factor-κB was observed in rats with CIRI that received I3C. I3C-treated rats with pathology showed decreased caspase activity and apoptosis-inducing factor expression, compared to the animals in the CIRI group. Obtained data indicate that I3C has a neuroprotective and anti-ischemic effect in CIRI that may be related to its antioxidant properties and ability to reduce the inflammatory response and apoptosis.

Diagnostic and prognostic value of serum S100B in sepsis-associated encephalopathy: A systematic review and meta-analysis

Background

In sepsis, brain dysfunction is known as Sepsis-associated encephalopathy (SAE), which often results in severe cognitive and neurological sequelae and increases the risk of death. Our systematic review and meta-analysis aimed to explore the diagnostic and prognostic value of serum S100 calcium-binding protein B (S100B) in SAE patients.

Methods

We conducted a systematic search of the databases PubMed, Web of Science, Embase, Cochrane databases, CNKI, VIP, and WFSD from their inception dates until August 20, 2022. A Meta-analysis of the included studies was also performed using Review Manager version 5.4 and Stata16.0.

Results

This meta-analysis included 28 studies with 1401 serum samples from SAE patients and 1591 serum samples from no-encephalopathy septic (NE) patients. The Meta-Analysis showed that individuals with SAE had higher serum S100B level than NE controls (MD, 0.49 [95% CI (0.37)-(0.60), Z =8.29, P < 0.00001]), and the baseline level of serum S100B in septic patients with burn was significantly higher than average (1.96 [95% CI (0.92)-(2.99), Z =3.71, P < 0.0002]) In addition, septic patients with favorable outcomes had lower serum S100B levels than those with unfavorable outcomes (MD, -0.35 [95% CI (-0.50)-(-0.20), Z =4.60, P < 0.00001]).

Conclusion

Our Meta-Analysis indicates that higher serum S100B level in septic patients are moderately associated with SAE and unfavorable outcomes (The outcomes here mainly refer to the mortality). The serum S100B level may be a useful diagnostic and prognostic biomarker of SAE.

Correlation Between Cognitive Impairment and Homocysteine and S100B Protein in Patients with Progressive Ischemic Stroke

PURPOSE

This study aimed to investigate the relationship between cognitive impairment and homocysteine (Hcy) and S100B protein in patients with progressive ischemic stroke (PIS).

PATIENTS AND METHODS

A total of 158 patients with PIS hospitalized in the Department of Neurology in Taixing People's Hospital from January 2020 to March 2022 were enrolled in the study. After 90 days of follow-up, the patients were divided into two groups according to the MoCA score-99 cases with cognitive impairment group (observation group) and 59 cases with cognitive normal group (control group). Causal diagram was drawn to assess the association between risk factors and PIS with observation group. The risk factors indicators of cognitive impairment in patients with PIS were screened. The related predictive indicators were screened by multivariate logistic regression analysis, and Pearson correlation analysis. The predictive value was analyzed by Receiver Operating Characteristic (ROC) curve.

RESULTS

Multivariate logistic regression analysis showed that age, hypertension, lesion position, Hcy and S100B protein were related risk factors for cognitive impairment in patients with PIS. Pearson correlation analysis was conducted between Hcy and S100 B protein and MoCA score, and revealed that Hcy and S100 B protein were negatively correlated with MoCA score. ROC curve analysis showed that the Area Under the Curve (AUC) of S100 B protein and Hcy in identifying cognitive impairment after PIS was 0.709 and 0.673, respectively, and the combined AUC of Hcy and S100B protein in predicting cognitive impairment after PIS was 0.739.

CONCLUSION

Hcy and S100B protein are related risk factors for cognitive impairment in patients with PIS, and may be used as in a prediction model to predict cognitive impairment after PIS in the future.

Receptors for Advanced Glycation End Products (RAGE): Promising Targets Aiming at the Treatment of Neurodegenerative Conditions

Advanced glycation end products (AGEs) are compounds formed after the non-enzymatic addition of reducing sugars to lipids, proteins, and nucleic acids. They are associated with the development of various clinical complications observed in diabetes and cardiovascular diseases, such as retinopathy, nephropathy, diabetic neuropathy, and others. In addition, compelling evidence indicates that these molecules participate in the progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Multiple cellular and molecular alterations triggered by AGEs that could alter homeostasis have been identified. One of the main targets for AGE signaling is the receptor for advanced glycation end-products (RAGE). Importantly, this receptor is the target of not only AGEs, but also amyloid β peptides, HMGB1 (high-mobility group box-1), members of the S100 protein family, and glycosaminoglycans. The activation of this receptor induces intracellular signaling cascades that are involved in pathological processes and cell death. Therefore, RAGE represents a key target for pharmacological interventions in neurodegenerative diseases. This review will discuss the various effects of AGEs and RAGE activation in the pathophysiology of neurodegenerative diseases, as well as the currently available pharmacological tools and promising drug candidates.

Risk of Dementia or Cognitive Impairment in Sepsis Survivals: A Systematic Review and Meta-Analysis

Background

There is growing evidence that sepsis survivors are at increased risk of developing new-onset atrial fibrillation, acute kidney injury, and neurological diseases. However, whether sepsis survivals increase the risk of dementia or cognitive impairment remains to be further explored.

Objective

The objective of this study was to determine whether sepsis survivals increase the risk of dementia or cognitive impairment.

Methods

We searched PubMed, Cochrane Library, Web of Science, and EMBASE databases for cohort studies or case-control studies from their inception to November 5, 2021. The quality of this study was assessed using the Newcastle-Ottawa Quality Assessment Scale (NOS). The Stata software (version 15.1) was used to calculate the odds ratio (OR) of dementia or cognitive impairment in sepsis survivals. Subgroup and sensitivity analyses were performed to assess the source of heterogeneity. Funnel plots and Egger's test were used to detect the publication bias.

Results

Eight studies (i.e., seven cohort studies and one case-control study) involving 891,562 individuals were included. The quality assessment results showed that the average score of NOS was over 7, and the overall quality of the included studies was high. Pooled analyses indicated that sepsis survivals were associated with an increased risk of all-cause dementia (OR = 1.62, 95% CI = 1.23-2.15, I 2 = 96.4%, p = 0.001). However, there was no obvious association between sepsis survivals and the risk of cognitive impairment (OR = 1.77, 95% CI = 0.59-5.32, I 2 = 87.4%, p = 0.306). Subgroup analyses showed that severe sepsis was associated with an increased risk of dementia or cognitive impairment (OR = 1.99, 95% CI = 1.19-3.31, I 2 = 75.3%, p = 0.008); such risk was higher than that of other unspecified types of sepsis (OR = 1.47, 95% CI = 1.04-2.09, I 2 = 97.6%, p = 0.029).

Conclusion

Sepsis survivals are associated with an increased risk of all-cause dementia but not with cognitive impairment. Appropriate management and prevention are essential to preserve the cognitive function of sepsis survivors and reduce the risk of dementia.

Environmental Enrichment Protects Against Sepsis-Associated Encephalopathy-Induced Learning and Memory Deficits by Enhancing the Synthesis and Release of Vasopressin in the Supraoptic Nucleus

Background

As a severe complication of sepsis, sepsis-associated encephalopathy (SAE) usually manifests as impaired learning and memory ability in survivors. Previous studies have reported that environmental enrichment (EE) can increase the learning and memory ability in different brain injury models. However, there has been no research on the possible positive effect of EE on SAE.

Aim

The present study aimed to test the effect of EE on SAE-induced impairment of learning and memory and its related mechanisms.

Methods

A Morris water maze test (MWM) was used to evaluate the learning and memory ability of SAE rats that received EE housing or not. The expression of vasopressin (VP) was assessed using immunofluorescence microscopy and enzyme-linked immunosorbent assays (ELISAs). The synthesis of VP in the supraoptic nucleus (SON) was determined using quantitative real-time reverse transcription-PCR analysis. Moreover, inflammatory markers and brain-derived neurotrophic factor (BDNF) were detected using ELISA.

Results

The results showed that SAE induced a decreased learning and memory ability, while EE reversed this impairment. EE also enhanced the synthesis and secretion of VP in the SON. Blocking the action of VP in the hippocampus interrupted the EE-induced amelioration of learning and memory impairment. Moreover, EE induced changes to the levels of BDNF and cytokines in the hippocampus and these effects were mediated by VP binding to the VP receptor 1a.

Conclusion

Our findings demonstrated that the enhanced synthesis and secretion of VP in the SON are a key determinant responsible for EE-induced alleviation of learning and memory deficits caused by SAE.