Glycemic control with insulin attenuates sepsis-associated encephalopathy by inhibiting glial activation via the suppression of the nuclear factor kappa B and mitogen-activated protein kinase signaling pathways in septic rats

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 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.

Mechanisms of Insulin Signaling as a Potential Therapeutic Method in Intestinal Diseases

Gastrointestinal diseases are becoming a growing public health problem. One of them is inflammatory bowel disease (IBD), which includes ulcerative colitis (UC) and Crohn's disease (CD). The incidence of IBD is increasing in developing countries and declining in developed countries, affecting people of all ages. Researchers have been exploring new treatment options including insulin signaling pathways in the inflammation of the gastrointestinal tract. It seems that a better understanding of the mechanism of IGF-1, GLP-1 and TL1A on the gut microbiota and inflammation may provide new advances in future therapeutic strategies for patients with IBD, but also other intestinal diseases. This review aims to synthesize insights into the effects of GLP, IGF and anti-TL1A on inflammation and the gut microbiota, which may enable their future use in therapy for people with intestinal diseases.

Orexin-A Attenuates the Inflammatory Response in Sepsis-Associated Encephalopathy by Modulating Oxidative Stress and Inhibiting the ERK/NF-κB Signaling Pathway in Microglia and Astrocytes

BACKGROUND

Oxidative stress-induced inflammation is a major pathogenic mechanism in sepsis-associated encephalopathy (SAE). We hypothesized that regulation of reactive oxygen species (ROS) by the neuropeptide orexin-A could prevent SAE-induced oxidative stress and inflammation. Therefore, the aim of this study was to investigate the effects of orexin-A on oxidative stress and inflammation in SAE in mice.

METHODS

Adult male mice were treated with orexin-A (250 μg/kg, intranasal administration) to establish a cecal ligation perforation (CLP) model. We performed behavioral tests, observed neuronal damage in the hippocampal region, measured the levels of ROS, NOX2, and observed the structure of mitochondria by transmission electron microscopy. We then examined the inflammatory factors TNF-α and IL-1β, the activation of microglia and astrocytes, the expression of ERK/NF-κB, C3, and S100A10, and the presence of A1 type astrocytes and A2 type astrocytes.

RESULTS

Orexin-A treatment improved cognitive performance in CLP-induced SAE mice, attenuated neuronal apoptosis in the hippocampal region, ameliorated ROS levels and the extent of mitochondrial damage, and reduced protein expression of NOX2 in hippocampal tissue. In addition, orexin-A treatment significantly reduced microglia and astrocyte activation, inhibited the levels of P-ERK and NF-κB, and reduced the release of IL-1β and TNF-α, which were significantly increased after CLP. Finally, Orexin-A treatment significantly decreased the number of C3/glial fibrillary acidic protein (GFAP)-positive cells and increased the number of S100A10/GFAP-positive cells.

CONCLUSION

Our data suggest that orexin-A reduces ROS expression by inhibiting CLP-induced NOX2 production, thereby attenuating mitochondrial damage and neuronal apoptosis. Its inhibition of microglial and A1-type astrocyte activation and inflammation was associated with the ERK/NF-κB pathway. These suggest that orexin-A may reduce cognitive impairment in SAE by reducing oxidative stress-induced inflammation.

miR-193b-3p/ PGC-1α pathway regulates an insulin dependent anti-inflammatory response in Parkinson's disease

It has been shown that many miRNAs, including miR-193b-3p, are differentially expressed in Parkinson's disease (PD). Dysregulation of miR-193b-3p/PGC-1α axis may alter homeostasis in cells and can induce an inflammatory response commonly accompanied by metabolic disturbances. The aim of the present study is to investigate if dysregulation of the miR-193-3p/PGC-1α axis may contribute to the pathological changes observed in the PD brain. Brain tissue were obtained from middle frontal gyrus of non-demented controls and individuals with a PD diagnosis. RT-qPCR was used to determine the expression of miR-193b-3p and in situ hybridization (ISH) and immunological analysis were employed to establish the cellular distribution of miR-193b-3p. Functional assays were performed using SH-SY5Y cells, including transfection and knock-down of miR-193b-3p. We found significantly lower expression of miR-193b-3p in the early stages of PD (PD4) which increased throughout disease progression. Furthermore, altered expression of PGC-1α suggested a direct inhibitory effect of miR-193b-3p in the brain of individuals with PD. Moreover, we observed changes in expression of insulin after transfection of SH-SY5Y cells with miR-193b-3p, which led to dysregulation in the expression of several pro- or anti - inflammatory genes. Our findings indicate that the miR-193b-3p/PGC-1α axis is involved in the regulation of insulin signaling. This regulation is crucial, since insulin induced inflammatory response may serve as a protective mechanism during acute situations but potentially evolve into a pathological process in chronic conditions. This novel regulatory mechanism may represent an interesting therapeutic target with potential benefits for various neurodegenerative diseases.

Therapeutic effects of orexin-A in sepsis-associated encephalopathy in mice

BACKGROUND

Sepsis-associated encephalopathy (SAE) causes acute and long-term cognitive deficits. However, information on the prevention and treatment of cognitive dysfunction after sepsis is limited. The neuropeptide orexin-A (OXA) has been shown to play a protective role against neurological diseases by modulating the inflammatory response through the activation of OXR1 and OXR2 receptors. However, the role of OXA in mediating the neuroprotective effects of SAE has not yet been reported.

METHODS

A mouse model of SAE was induced using cecal ligation perforation (CLP) and treated via intranasal administration of exogenous OXA after surgery. Mouse survival, in addition to cognitive and anxiety behaviors, were assessed. Changes in neurons, cerebral edema, blood-brain barrier (BBB) permeability, and brain ultrastructure were monitored. Levels of pro-inflammatory factors (IL-1β, TNF-α) and microglial activation were also measured. The underlying molecular mechanisms were investigated by proteomics analysis and western blotting.

RESULTS

Intranasal OXA treatment reduced mortality, ameliorated cognitive and emotional deficits, and attenuated cerebral edema, BBB disruption, and ultrastructural brain damage in mice. In addition, OXA significantly reduced the expression of the pro-inflammatory factors IL-1β and TNF-α, and inhibited microglial activation. In addition, OXA downregulated the expression of the Rras and RAS proteins, and reduced the phosphorylation of P-38 and JNK, thus inhibiting activation of the MAPK pathway. JNJ-10,397,049 (an OXR2 blocker) reversed the effect of OXA, whereas SB-334,867 (an OXR1 blocker) did not.

CONCLUSION

This study demonstrated that the intranasal administration of moderate amounts of OXA protects the BBB and inhibits the activation of the OXR2/RAS/MAPK pathway to attenuate the outcome of SAE, suggesting that OXA may be a promising therapeutic approach for the management of SAE.

Down-regulating nuclear factor of activated T cells 1 alleviates cognitive deficits in a mouse model of sepsis-associated encephalopathy, possibly by stimulating hippocampal neurogenesis

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis, and has been associated with increased morbidity and mortality. Nuclear factor of activated T cells (NFATs) 1, a transcriptional factor that regulates T cell development, activation and differentiation, has been implicated in neuronal plasticity. Here we examined the potential role of NFAT1 in sepsis-associated encephalopathy in mice. Adult male C57BL/6J mice received intracerebroventricular injections of short interfering RNA against NFAT1 or sex-determining region Y-box 2 (SOX2), or a scrambled control siRNA prior to cecal ligation and perforation (CLP). A group of mice receiving sham surgery were included as an additional control. CLP increased escape latency and decreased the number of crossings into, and total time spent within, the target quadrant in the Morris water maze test. CLP also decreased the freezing time in context-dependent, but not context-independent, fear conditioning test. Knockdown of either NFAT1 or SOX2 attenuated these behavioral deficits. NFAT1 knockdown also attenuated CLP-induced upregulation of SOX2, increased the numbers of nestin-positive cells and newborn astrocytes, reduced the number of immature newborn neurons, and promoted the G1 to S transition of neural stem cells in hippocampus. These findings suggest that NFAT1 may contribute to sepsis-induced behavioral deficits, possibly by promoting SOX2 signaling and neurogenesis.

S100A9 exerts insulin-independent antidiabetic and anti-inflammatory effects

Type 1 diabetes mellitus (T1DM) is characterized by insulin deficiency leading to hyperglycemia and several metabolic defects. Insulin therapy remains the cornerstone of T1DM management, yet it increases the risk of life-threatening hypoglycemia and the development of major comorbidities. Here, we report an insulin signaling-independent pathway able to improve glycemic control in T1DM rodents. Co-treatment with recombinant S100 calcium-binding protein A9 (S100A9) enabled increased adherence to glycemic targets with half as much insulin and without causing hypoglycemia. Mechanistically, we demonstrate that the hyperglycemia-suppressing action of S100A9 is due to a Toll-like receptor 4-dependent increase in glucose uptake in specific skeletal muscles (i.e., soleus and diaphragm). In addition, we found that T1DM mice have abnormal systemic inflammation, which is resolved by S100A9 therapy alone (or in combination with low insulin), hence uncovering a potent anti-inflammatory action of S100A9 in T1DM. In summary, our findings reveal the S100A9-TLR4 skeletal muscle axis as a promising therapeutic target for improving T1DM treatment.

Molecular Mechanisms for the Vicious Cycle between Insulin Resistance and the Inflammatory Response in Obesity

The comprehensive anabolic effects of insulin throughout the body, in addition to the control of glycemia, include ensuring lipid homeostasis and anti-inflammatory modulation, especially in adipose tissue (AT). The prevalence of obesity, defined as a body mass index (BMI) ≥ 30 kg/m², has been increasing worldwide on a pandemic scale with accompanying syndemic health problems, including glucose intolerance, insulin resistance (IR), and diabetes. Impaired tissue sensitivity to insulin or IR paradoxically leads to diseases with an inflammatory component despite hyperinsulinemia. Therefore, an excess of visceral AT in obesity initiates chronic low-grade inflammatory conditions that interfere with insulin signaling via insulin receptors (INSRs). Moreover, in response to IR, hyperglycemia itself stimulates a primarily defensive inflammatory response associated with the subsequent release of numerous inflammatory cytokines and a real threat of organ function deterioration. In this review, all components of this vicious cycle are characterized with particular emphasis on the interplay between insulin signaling and both the innate and adaptive immune responses related to obesity. Increased visceral AT accumulation in obesity should be considered the main environmental factor responsible for the disruption in the epigenetic regulatory mechanisms in the immune system, resulting in autoimmunity and inflammation.

High Glucose Promotes Inflammation and Weakens Placental Defenses against E. coli and S. agalactiae Infection: Protective Role of Insulin and Metformin

Placentas from gestational diabetes mellitus (GDM) patients undergo significant metabolic and immunologic adaptations due to hyperglycemia, which results in an exacerbated synthesis of proinflammatory cytokines and an increased risk for infections. Insulin or metformin are clinically indicated for the treatment of GDM; however, there is limited information about the immunomodulatory activity of these drugs in the human placenta, especially in the context of maternal infections. Our objective was to study the role of insulin and metformin in the placental inflammatory response and innate defense against common etiopathological agents of pregnancy bacterial infections, such as E. coli and S. agalactiae, in a hyperglycemic environment. Term placental explants were cultivated with glucose (10 and 50 mM), insulin (50–500 nM) or metformin (125–500 µM) for 48 h, and then they were challenged with live bacteria (1 × 105 CFU/mL). We evaluated the inflammatory cytokine secretion, beta defensins production, bacterial count and bacterial tissue invasiveness after 4–8 h of infection. Our results showed that a GDM-associated hyperglycemic environment induced an inflammatory response and a decreased beta defensins synthesis unable to restrain bacterial infection. Notably, both insulin and metformin exerted anti-inflammatory effects under hyperglycemic infectious and non-infectious scenarios. Moreover, both drugs fortified placental barrier defenses, resulting in reduced E. coli counts, as well as decreased S. agalactiae and E. coli invasiveness of placental villous trees. Remarkably, the double challenge of high glucose and infection provoked a pathogen-specific attenuated placental inflammatory response in the hyperglycemic condition, mainly denoted by reduced TNF-α and IL-6 secretion after S. agalactiae infection and by IL-1β after E. coli infection. Altogether, these results suggest that metabolically uncontrolled GDM mothers develop diverse immune placental alterations, which may help to explain their increased vulnerability to bacterial pathogens.

Electroacupuncture Alleviates Neuroinflammation by Inhibiting the HMGB1 Signaling Pathway in Rats with Sepsis-Associated Encephalopathy

Sepsis-Associated Encephalopathy (SAE) is common in sepsis patients, with high mortality rates. It is believed that neuroinflammation is an important mechanism involved in SAE. High mobility group box 1 protein (HMGB1), as a late pro-inflammatory factor, is significantly increased during sepsis in different brain regions, including the hippocampus. HMGB1 causes neuroinflammation and cognitive impairment through direct binding to advanced glycation end products (RAGE) and Toll-like receptor 4 (TLR4). Electroacupuncture (EA) at Baihui (GV20) and Zusanli (ST36) is beneficial for neurological diseases and experimental sepsis. Our study used EA to treat SAE induced by lipopolysaccharide (LPS) in male Sprague-Dawley rats. The Y maze test was performed to assess working memory. Immunofluorescence (IF) and Western blotting (WB) were used to determine neuroinflammation and the HMGB1 signaling pathway. Results showed that EA could improve working memory impairment in rats with SAE. EA alleviated neuroinflammation by downregulating the hippocampus's HMGB1/TLR4 and HMGB1/RAGE signaling, reducing the levels of pro-inflammatory factors, and relieving microglial and astrocyte activation. However, EA did not affect the tight junctions' expression of the blood-brain barrier (BBB) in the hippocampus.

The interplay between oral microbes and immune responses

Oral microbes play a critical role in maintaining oral homeostasis. Microbial dysbiosis promotes disease pathogenesis through several mechanisms. Recent studies have revealed that microbial imbalance and sustained inflammation are involved in disease progression. The adverse interaction triggered by a host immune response to microorganisms can lead to oral and systemic diseases. Here, we reviewed how oral microbes communicate with hosts during the development of local and distant inflammation. Elucidation of these processes may reveal future directions in this field and the potential targets of novel biological therapies for oral and systemic diseases.

Machine learning for early prediction of sepsis-associated acute brain injury

Background

Sepsis-associated encephalopathy (SAE) is defined as diffuse brain dysfunction associated with sepsis and leads to a high mortality rate. We aimed to develop and validate an optimal machine-learning model based on clinical features for early predicting sepsis-associated acute brain injury.

Methods

We analyzed adult patients with sepsis from the Medical Information Mart for Intensive Care (MIMIC III) clinical database. Candidate models were trained using random forest, support vector machine (SVM), decision tree classifier, gradients boosting machine (GBM), multiple layer perception (MLP), extreme gradient boosting (XGBoost), light gradients boosting machine (LGBM) and a conventional logistic regression model. These methods were applied to develop and validate the optimal model based on its accuracy and area under curve (AUC).

Results

In total, 12,460 patients with sepsis met inclusion criteria, and 6,284 (50.4%) patients suffered from sepsis-associated acute brain injury. Compared other models, the LGBM model achieved the best performance. The AUC for both train set and test set indicated excellent validity (Trainset AUC 0.91, Testset AUC 0.87). Feature importance analysis showed that glucose, age, mean arterial pressure, heart rate, hemoglobin, and length of ICU stay were the top 6 important clinical factors to predict occurrence of sepsis-associated acute brain injury.

Conclusion

Almost half of patients admitted to ICU with sepsis had sepsis-associated acute brain injury. The LGBM model better identify patients with sepsis-associated acute brain injury than did other machine-learning models. Glucose, age, and mean arterial pressure were the three most important clinical factors to predict occurrence of sepsis-associated acute brain injury.

The Many Faces of Astrocytes in the Septic Brain

Sepsis is a life-threatening organ dysfunction that is caused by a dysregulated host response to infection. Surviving patients have cognitive and memory damage that started during sepsis. These neurologic damages have been associated with increased BBB permeability and microglial activation. However, a few discrete studies have seen over the years pointing to the potential role of astrocytes in the pathophysiology of neurological damage after sepsis. The purpose of this article is to review information on the potential role of astrocytes during sepsis, as well as to provoke further studies in this area. These published articles show astrocytic activation after sepsis; they also evidence the release of inflammatory mediators by these cells. In this sense, the role of astrocytes should be better elucidated during sepsis progression.

Reprogramming Macrophage Metabolism and its Effect on NLRP3 Inflammasome Activation in Sepsis

Sepsis, the most common life-threatening multi-organ dysfunction syndrome secondary to infection, lacks specific therapeutic strategy due to the limited understanding of underlying mechanisms. It is currently believed that inflammasomes play critical roles in the development of sepsis, among which NLRP3 inflammasome is involved to most extent. Recent studies have revealed that dramatic reprogramming of macrophage metabolism is commonly occurred in sepsis, and this dysregulation is closely related with the activation of NLRP3 inflammasome. In view of the fact that increasing evidence demonstrates the mechanism of metabolism reprogramming regulating NLRP3 activation in macrophages, the key enzymes and metabolites participated in this regulation should be clearer for better interpreting the relationship of NLRP3 inflammasome and sepsis. In this review, we thus summarized the detail mechanism of the metabolic reprogramming process and its important role in the NLRP3 inflammasome activation of macrophages in sepsis. This mechanism summarization will reveal the applicational potential of metabolic regulatory molecules in the treatment of sepsis.

Correlation Analysis of Blood Glucose Level with Inflammatory Response and Immune Indicators in Patients with Sepsis

Objective

To analyze the correlation of blood glucose level with inflammatory response and immune indicators in patients with sepsis.

Methods

Between February 2019 and February 2021, 30 sepsis patients and 30 sepsis patients complicated with diabetes mellitus admitted to our hospital were recruited and assigned to either the experimental group (sepsis patients) or the observation group (sepsis patients with diabetes mellitus). Another 30 healthy subjects in the same period were included as the control group. The levels of IL-6, TNF-α, IL-1β, CD4+, and CD8+ in the three groups of patients were compared to analyze the correlation of blood glucose levels with inflammatory response and immune indicators in patients with sepsis. The difference of counting data was analyzed using the chi-square test, and the difference of measurement data was analyzed using the t-test.

Results

The control group showed the lowest levels of IL-6 at 14.32 ± 4.98 pg/ml, followed by 18.33 ± 3.27 pg/ml in the experimental group and then 22.64 ± 5.16 pg/ml in the observation group (P < 0.05). The levels of other inflammatory factors including TNF-α and IL-1β were the lowest in the control group, followed by the experimental group, and then the observation group (P < 0.05). The lowest immune function indicator CD4+ and CD8+ levels were found in the observation group, followed by the experimental group, and then the control group (P < 0.05). The blood glucose level of patients with sepsis was positively correlated with the levels of IL-6, TNF-α, and IL-1β and was negatively correlated with the levels of CD4+/CD8+. The higher the blood glucose, the lower the number of immune cells.

Conclusion

The blood glucose level of patients with sepsis is positively correlated with inflammatory response and negatively with immune indicators. An increased blood sugar level is associated with aggravated inflammatory responses and a decreased number of immune cells, which provides a reference for the disease severity assessment and treatment of patients with sepsis.

VIP alleviates sepsis-induced cognitive dysfunction as the TLR-4/NF-κB signaling pathway is inhibited in the hippocampus of rats

Cognitive dysfunction caused by sepsis-associated encephalopathy (SAE) is still poorly understood. It is reported that vasoactive intestinal peptide (VIP) exerts its anti-inflammatory effects in multiple diseases, while its biological function in SAE remains unclear. We aimed to figure out whether VIP has influence on sepsis-induced neuroinflammation and cognitive dysfunction. To induce sepsis, rats were subjected to cecal ligation and puncture (CLP) operation. Morris water maze test and fear conditioning test were conducted to reveal cognitive dysfunctions. TUNEL assay was performed to evaluate apoptosis. We found out that the expression of VIP was downregulated in the hippocampus of septic rats. VIP was verified to attenuate sepsis-induced memory impairment following CLP. Additionally, we examined apoptosis and inflammation in rats' hippocampus. It is worth noting that VIP inhibited the apoptosis in the hippocampus and reduced the productions of proinflammatory cytokines TNF-α, IL-6 and IL-1β. Furthermore, our data confirmed that VIP was involved in regulating the TLR-4/NF-κB signaling. In conclusion, VIP inhibited neuroinflammation and cognitive impairment in hippocampus of septic rats through the TLR-4/NF-κB signaling pathway.

Blood-Brain Barrier Disruption by Lipopolysaccharide and Sepsis-Associated Encephalopathy

As a complex multicellular structure of the vascular system at the central nervous system (CNS), the blood-brain barrier (BBB) separates the CNS from the system circulation and regulates the influx and efflux of substances to maintain the steady-state environment of the CNS. Lipopolysaccharide (LPS), the cell wall component of Gram-negative bacteria, can damage the barrier function of BBB and further promote the occurrence and development of sepsis-associated encephalopathy (SAE). Here, we conduct a literature review of the direct and indirect damage mechanisms of LPS to BBB and the relationship between these processes and SAE. We believe that after LPS destroys BBB, a large number of inflammatory factors and neurotoxins will enter and damage the brain tissue, which will activate brain immune cells to mediate inflammatory response and in turn further destroys BBB. This vicious circle will ultimately lead to the progression of SAE. Finally, we present a succinct overview of the treatment of SAE by restoring the BBB barrier function and summarize novel opportunities in controlling the progression of SAE by targeting the BBB.

Infection and Immunometabolism in the Central Nervous System: A Possible Mechanistic Link Between Metabolic Imbalance and Dementia

Metabolic syndromes are frequently associated with dementia, suggesting that the dysregulation of energy metabolism can increase the risk of neurodegeneration and cognitive impairment. In addition, growing evidence suggests the link between infections and brain disorders, including Alzheimer's disease. The immune system and energy metabolism are in an intricate relationship. Infection triggers immune responses, which are accompanied by imbalance in cellular and organismal energy metabolism, while metabolic disorders can lead to immune dysregulation and higher infection susceptibility. In the brain, the activities of brain-resident immune cells, including microglia, are associated with their metabolic signatures, which may be affected by central nervous system (CNS) infection. Conversely, metabolic dysregulation can compromise innate immunity in the brain, leading to enhanced CNS infection susceptibility. Thus, infection and metabolic imbalance can be intertwined to each other in the etiology of brain disorders, including dementia. Insulin and leptin play pivotal roles in the regulation of immunometabolism in the CNS and periphery, and dysfunction of these signaling pathways are associated with cognitive impairment. Meanwhile, infectious complications are often comorbid with diabetes and obesity, which are characterized by insulin resistance and leptin signaling deficiency. Examples include human immunodeficiency virus (HIV) infection and periodontal disease caused by an oral pathogen Porphyromonas gingivalis. This review explores potential interactions between infectious agents and insulin and leptin signaling pathways, and discuss possible mechanisms underlying the relationship between infection, metabolic dysregulation, and brain disorders, particularly focusing on the roles of insulin and leptin.

Comprehensive analysis of mRNAs, lncRNAs and circRNAs in the early phase of microglial activation

Sepsis-associated encephalopathy (SAE) is a common complication of sepsis that may seriously affect the prognosis and quality of life of patients with sepsis. Microglial activation is vital to the neuroinflammation and the pathology of SAE. In the present study, in vitro cultured BV-2 microglial cells stimulated with lipopolysaccharide (LPS) were employed as a model of microglia activation. The altered profiles of long noncoding (lnc)RNAs, circular (circ)RNAs and mRNAs in BV-2 cells after 4 h of LPS exposure were arrayed by using the Agilent competing endogenous (ce)RNA Microarray Chip. Using fold change >2 and P<0.05 as the cutoff criteria, 1,135 mRNAs and 2,488 lncRNAs were determined to be upregulated and 630 mRNAs and 744 lncRNAs to be downregulated. The number of differentially expressed circRNAs was lower, with 140 upregulated and 123 downregulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of DE mRNAs suggested that inflammatory responses, as well as lipid metabolism, were involved in microglial activation. Furthermore, analyses of ceRNA networks of the lncRNA-miRNA-mRNA or circRNA-miRNA-mRNA interrelations were performed. The present study revealed a multitude of novel candidate mRNAs, lncRNAs and circRNAs involved in microglial activation, which may improve the current knowledge on neuroinflammation and provide potential therapeutic targets for SAE.

Insulin Reduces Inflammation by Regulating the Activation of the NLRP3 Inflammasome

The NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is the platform for IL-1β maturation, aimed at mediating a rapid immune response against danger signals which must be tightly regulated. Insulin is well known as the critical hormone in the maintenance of glucose in physiologic response. Previous studies have proved insulin has the anti-inflammatory effect but the molecular mechanism of immunomodulation provided by insulin is not clear so far. Here we investigated whether insulin reduces inflammation by regulating the NLRP3 inflammasome. In the present study, we used LPS and ATP to induce the intracellular formation of the NLRP3 inflammasome. Insulin inhibited the secretion of IL-1β by preventing the assembly of the ASC in THP-1 cells and human CD14⁺ monocyte-derived macrophages. The phosphorylation status of Syk, p38 mitogen−activated protein kinase (MAPK) and ASC were altered by insulin. These effects were attenuated in THP-1 cells transfected with small interfering RNA targeting insulin receptors. In vivo, administration of glucose–insulin–potassium reduced serum IL-1β level, intestinal ASC speck formation, local macrophage infiltration and alleviated intestinal injury in mice exposed to LPS. Insulin may play an immunomodulatory role in anti-inflammation by regulating the NLRP3 inflammasome.

Sepsis-associated encephalopathy and septic encephalitis: an update

INTRODUCTION

Sepsis-associated encephalopathy (SAE) and septic encephalitis (SE) are associated with increased mortality, long-term cognitive impairment, and focal neurological deficits.

AREAS COVERED

The PUBMED database was searched 2016-2020. The clinical manifestation of SAE is delirium, SE additionally is characterized by focal neurological symptoms. SAE is caused by inflammation with endothelial/microglial activation, increase of permeability of the blood-brain-barrier, hypoxia, imbalance of neurotransmitters, glial activation, axonal, and neuronal loss. Septic-embolic (SEE) and septic-metastatic encephalitis (SME) are characterized by focal ischemia (SEE) and small abscesses (SME). The continuum between SAE, SME, and SEE is documented by imaging techniques and autopsies. The backbone of treatment is rapid optimum antibiotic therapy. Experimental approaches focus on modulation of inflammation, stabilization of the blood-brain barrier, and restoration of membrane/mitochondrial function.

EXPERT OPINION

The most promising diagnostic approaches are new imaging techniques. The most important measure to fight delirium remains establishment of daily structure and adequate sensory stimuli. Dexmedetomidine and melatonin appear to reduce the frequency of delirium, their efficacy in SAE and SE remains to be established. Drugs already licensed for other indications or available as food supplements which may be effective in SAE are statins, L-DOPA/benserazide, β-hydroxybutyrate, palmitoylethanolamide, and tetracyclines or other bactericidal non-lytic antibiotics.