Correlation of Acute Phase Inflammatory and Oxidative Markers With Long-term Cognitive Impairment in Sepsis Survivors Rats

Cannabidiol effect on long-term brain alterations in septic rats: Involvement of PPARγ activation

Sepsis is a life-threatening condition induced by a deregulated host response to infection. Post-sepsis injury includes long-term cognitive impairment, whose neurobiological mechanisms and effective treatment remain unknown. The present study was designed to determine the potential effects of cannabidiol (CBD) in a sepsis-associated encephalopathy (SAE) model and explore if peroxisome proliferator activated receptor gamma (PPARγ) is the putative mechanism underpinning the beneficial effects. SAE was induced in Wistar rats by cecal ligation and puncture (CLP) or sham (control). CLP rats received vehicle, CBD (10 mg/kg), PPARγ inhibitor (GW9662 - 1 mg/kg), or GW9662 (1 mg/kg) + CBD (10 mg/kg) intraperitoneally for ten days. During this period, the survival rate was recorded, and at the end of 10 days, a memory test was performed, and the prefrontal cortex and hippocampus were removed to verify brain-derived neurotrophic factor (BDNF), cytokines (IL-1β, IL-6 and IL-10), myeloperoxidase activity, nitrite nitrate concentration, and lipid and protein carbonylation and catalase activity. Septic rats presented cognitive decline and an increase in mortality following CLP. Only CBD alone improved the cognitive impairment, which was accompanied by restoration of BDNF, reduced neuroinflammation, and oxidative stress, mainly in the hippocampus. This study shows that CLP induces an increase in brain damage and CBD has neuroprotective effects on memory impairment and neurotrophins, as well as against neuroinflammation and oxidative stress, and is mediated by PPARγ activation.

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.

Potential of piperine for neuroprotection in sepsis-associated encephalopathy

AIMS

Sepsis-associated encephalopathy (SAE) is a common complication that increases mortality and leads to long-term cognitive impairment in sepsis survivors. However, no specific or effective therapy has been identified for this complication. Piperine is an alkaloid known for its anti-inflammatory, antioxidant, and neuroprotective properties, which are important characteristics for treatment of SAE. The objective of this study was to evaluate the neuroprotective effect of piperine on SAE in C57BL/6 mice that underwent cecum ligation and perforation surgery (CLP).

MAIN METHODS

C57BL/6 male mice were randomly assigned to groups that underwent SHAM surgery or CLP. Mice in the CLP group were treated with piperine at doses of 20 or 40 mg/kg for short- (5 days) or long-term (10 days) periods after CLP.

KEY FINDINGS

Our results revealed that untreated septic animals exhibited increased concentrations of IL-6, TNF, VEGF, MMP-9, TBARS, and NLRP3, and decreased levels of BDNF, sulfhydryl groups, and catalase in the short term. Additionally, the levels of carbonylated proteins and degenerated neuronal cells were increased at both time points. Furthermore, short-term and visuospatial memories were impaired. Piperine treatment reduced MMP-9 activity in the short term and decreased the levels of carbonylated proteins and degenerated neuronal cells in the long term. It also lowered IL-6 and TBARS levels at both time points evaluated. Moreover, piperine increased short-term catalase and long-term BDNF factor levels and improved memory at both time points.

SIGNIFICANCE

In conclusion, our data demonstrate that piperine exerts a neuroprotective effect on SAE in animals that have undergone CLP.

The effect of modafinil on passive avoidance memory, brain level of BDNF and oxidative stress markers in sepsis survivor rats

Propose/aim of study: Modafinil (MD) is a psychostimulant drug used off-label and cognitive dysfunction may be a significant emerging treatment target for this drug. The objective of this study was to evaluate the effect of MD on the neurochemical parameters and memory impairment of rats submitted to sepsis by cecal ligation and perforation (CLP).Material and method: Male Wistar rats (250-350g) were submitted to CLP, or sham as control, and divided into the sham + water, sham + MD (300 mg/kg), CLP + water, and CLP + MD (300 mg/kg) groups. Ten days after the administration of MD and CLP, the rats were submitted to a memory test by passive avoidance apparatus being sacrificed. The nitrite and nitrate (N/N) concentration, myeloperoxidase (MPO) and catalase (CAT) activity, lipid and protein oxidative damage, and brain-derived neurotrophic factor (BDNF) levels were measured in the prefrontal cortex and hippocampus.Results: The passive avoidance test verified an increase in the latency time compared training and test section in the groups sham + water and CLP + MD. Decreased N/N concentration and MPO activity were verified in the prefrontal cortex of rats submitted to CLP and MD treatment, as well as reduced protein and lipid oxidative damage in the hippocampus, which was accompanied by increased CAT activity and BDNF levels.Conclusion: Our data indicate the role of MD in attenuating oxidative stress parameters, the alteration of BDNF, and an improvement in memory impairment in rats ten days after induction of sepsis.

Diabetes Exacerbates Sepsis-Induced Neuroinflammation and Brain Mitochondrial Dysfunction

Sepsis is a life-threatening organ dysfunction, which demands notable attention for its treatment, especially in view of the involvement of immunodepressed patients, as the case of patients with diabetes mellitus (DM), who constitute a population susceptible to develop infections. Thus, considering this endocrine pathology as an implicatory role on the immune system, the aim of this study was to show the relationship between this disease and sepsis on neuroinflammatory and neurochemical parameters. Levels of IL-6, IL-10, brain-derived neurotrophic factor (BDNF), nerve growth factor (NGF), and mitochondrial respiratory chain complexes were evaluated in the hippocampus and prefrontal cortex 24 h after sepsis by cecal ligation and perforation (CLP) in Wistar rats induced to type 1 diabetes by alloxan (150 mg/kg). It was verified that diabetes implied immune function after 24 h of sepsis, since it contributed to the increase of the inflammatory process with higher production of IL-6 and decreased levels of IL-10 only in the hippocampus. In the same brain area, a several decrease in NGF level and activity of complexes I and II of the mitochondrial respiratory chain were observed. Thus, diabetes exacerbates neuroinflammation and results in mitochondrial impairment and downregulation of NGF level in the hippocampus after sepsis.

Systemic Response to Infection Induces Long-Term Cognitive Decline: Neuroinflammation and Oxidative Stress as Therapeutical Targets

In response to pathogens or damage signs, the immune system is activated in order to eliminate the noxious stimuli. The inflammatory response to infectious diseases induces systemic events, including cytokine storm phenomenon, vascular dysfunction, and coagulopathy, that can lead to multiple-organ dysfunction. The central nervous system (CNS) is one of the major organs affected, and symptoms such as sickness behavior (depression and fever, among others), or even delirium, can be observed due to activation of endothelial and glial cells, leading to neuroinflammation. Several reports have been shown that, due to CNS alterations caused by neuroinflammation, some sequels can be developed in special cognitive decline. There is still no any treatment to avoid cognitive impairment, especially those developed due to systemic infectious diseases, but preclinical and clinical trials have pointed out controlling neuroinflammatory events to avoid the development of this sequel. In this minireview, we point to the possible mechanisms that triggers long-term cognitive decline, proposing the acute neuroinflammatory events as a potential therapeutical target to treat this sequel that has been associated to several infectious diseases, such as malaria, sepsis, and, more recently, the new SARS-Cov2 infection.

Cytokines in the Brain and Neuroinflammation: We Didn’t Starve the Fire!

In spite of the brain-protecting tissues of the skull, meninges, and blood-brain barrier, some forms of injury to or infection of the CNS can give rise to cerebral cytokine production and action and result in drastic changes in brain function and behavior. Interestingly, peripheral infection-induced systemic inflammation can also be accompanied by increased cerebral cytokine production. Furthermore, it has been recently proposed that some forms of psychological stress may have similar CNS effects. Different conditions of cerebral cytokine production and action will be reviewed here against the background of neuroinflammation. Within this context, it is important to both deepen our understanding along already taken paths as well as to explore new ways in which neural functioning can be modified by cytokines. This, in turn, should enable us to put forward different modes of cerebral cytokine production and action in relation to distinct forms of neuroinflammation.

The Protective Effect of PK-11195 on Cognitive Impairment in Rats Survived of Polymicrobial Sepsis

Sepsis is an organ dysfunction caused by a host's unregulated response to infection, causing long-term brain dysfunction with microglial activation, the release of inflammatory components, and mitochondrial changes. Neuroinflammation can increase the expression of the 18-kD translocator protein (TSPO) in the mitochondria, leading to the activation of the microglia and the release of inflammatory components. The antagonist PK-11195 can modulate TSPO and reduce microglial activation and cognitive damage presented in an animal model of sepsis. The aim of this was to evaluate the effects of PK-11195 on long-term brain inflammation and cognitive impairment in an animal model of sepsis. Wistar rats, 60 days old, were submitted to cecal ligation and puncture (CLP) surgery, divided into groups control/saline, control/PK-11195, sepsis/saline, and sepsis/PK-11195. Immediately after surgery, the antagonist PK-11195 was administered at a dose of 3 mg/kg. Ten days after CLP surgery, the animals were submitted to behavioral tests and determination of brain inflammatory parameters. The sepsis/saline group presented cognitive damage. However, there was damage prevention in animals that received PK-11195. Besides, the sepsis increased the levels of cytokines and M1 microglia markers and caused oxidative damage. However, PK-11195 had the potential to decrease inflammation. These events show that the modulation of neuroinflammation during sepsis by PK-11195, possibly related to changes in TSPO, improves mitochondrial function in the animals' brains. In conclusion, the antagonist PK-11195 attenuated brain inflammation and prevented cognitive impairment in animals subjected to sepsis.

Stanniocalcin 1 Inhibits the Inflammatory Response in Microglia and Protects Against Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy is a serious consequence of sepsis, triggered by the host response against an infectious agent, that can lead to brain damage and cognitive impairment. Several mechanisms have been proposed in this bidirectional communication between the immune system and the brain after sepsis as neuroinflammation, oxidative stress, and mitochondrial dysfunction. Stanniocalcin-1 (STC-1), an endogen neuroprotective protein, acts as an anti-inflammatory and suppresses superoxide generation through induction of uncoupling proteins (UCPs) in the mitochondria. Here, we demonstrated a protective role of STC-1 on inflammatory responses in vitro, in activated microglia stimulated with LPS, and on neuroinflammation, oxidative stress, and mitochondrial function in the hippocampus of rats subjected to an animal model of sepsis by cecal ligation and puncture (CLP), as well the consequences on long-term memory. Recombinant human STC-1 (rhSTC1) suppressed the pro-inflammatory cytokine production in LPS-stimulated microglia without changing the UCP-2 expression. Besides, rhSTC1 injected into the cisterna magna decreased acute hippocampal inflammation and oxidative stress and increased the activity of complex I and II activity of mitochondrial respiratory chain and creatine kinase at 24 h after sepsis. rhSTC1 was effective in preventing long-term cognitive impairment after CLP. In conclusion, rhSTC1 confers significant neuroprotection by inhibiting the inflammatory response in microglia and protecting against sepsis-associated encephalopathy in rats.

Probiotics Exert Protective Effect against Sepsis-Induced Cognitive Impairment by Reversing Gut Microbiota Abnormalities

Recent evidence has revealed that probiotics could affect neurodevelopment and cognitive function via regulating gut microbiota. However, the role of probiotics in sepsis-associated encephalopathy (SAE) remained unclear. This study was conducted to assess the effects and therapeutic mechanisms of probiotic Clostridium butyricum (Cb) against SAE in mice. The SAE model mouse was induced by cecal ligation and puncture (CLP) and was given by intragastric administration with Cb for 1 month. A series of behavioral tests, including neurological severity score, tail suspension test, and elevated maze test, were used to assess cognitive impairment. Nissl staining and Fluoro-Jade C (FJC) staining were used to assess neuronal injury. Microglia activation, the release of neuroinflammatory cytokines, and the levels of ionized calcium-binding adapter molecule 1 (Iba-1) and brain-derived neurotrophic factor (BDNF) in the brain were determined. The compositions of the gut microbiota were detected by 16S rRNA sequencing. Our results revealed that Cb significantly attenuated cognitive impairment and neuronal damage. Moreover, Cb significantly inhibited excessive activation of microglia, decreased Iba-1 level, and increased BDNF level in the SAE mice. In addition, Cb improved gut microbiota dysbiosis of SAE mice. These findings revealed that Cb exerted anti-inflammatory effects and improved cognitive impairment in SAE mice, and their neuroprotective mechanisms might be mediated by regulating gut microbiota.

What animal models can tell us about long-term cognitive dysfunction following sepsis: A systematic review

Survivors of sepsis often develop long-term cognitive impairments. This review aimed at exploring the results of the behavioral tools and tests which have been used to evaluate cognitive dysfunction in different animal models of sepsis. Two independent investigators searched for sepsis- and cognition-related keywords. 6323 publications were found, of which 355 were selected based on their title, and 226 of these were chosen based on manuscript review. LPS was used to induce sepsis in 171 studies, while CLP was used in 55 studies. Inhibitory avoidance was the most widely used method for assessing aversive memory, followed by fear conditioning and continuous multi-trial inhibitory avoidance. With regard to non-aversive memory, most studies used the water maze, open-field, object recognition, Y-maze, plus maze, and radial maze tests. Both CLP and LPS models of sepsis were effective in inducing short- and long-term behavioral impairment. Our findings help elucidate the mechanisms involved in the pathophysiology of sepsis-induced cognitive changes, as well as the available methods and tests used to study this in animal models.

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

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

Sepsis and Cerebral Dysfunction: BBB Damage, Neuroinflammation, Oxidative Stress, Apoptosis and Autophagy as Key Mediators and the Potential Therapeutic Approaches

Sepsis-associated cerebral dysfunction is complex pathophysiology, generated from primary infections that are developed elsewhere in the body. The neonates, elderly population and chronically ill and long-term hospitalized patients are predominantly vulnerable to sepsis and related cerebral damage. Generally, electrophysiological recordings, severity and sedation scales, computerized imaging and spectroscopy techniques are used for its detection and diagnosis. About the underlying mechanisms, enhanced blood-brain barrier permeability and metalloprotease activity, tight junction protein loss and endothelial cell degeneration promote the influx of inflammatory and toxic mediators into the brain, triggering cerebrovascular damage. An altered neutrophil count and phenotype further dysregulate the normal neuroimmune responses and neuroendocrine stability via modulated activation of protein kinase C-delta, nuclear factor kappa-B and sphingolipid signaling. Glial activation, together with pro-inflammatory cytokines and chemokines and the Toll-like receptor, destabilize the immune system. Moreover, superoxides and hydroperoxides generate oxidative stress and perturb mitochondrial dynamics and ATP synthesis, propagating neuronal injury cycle. Activated mitochondrial apoptotic pathway, characterized by increased caspase-3 and caspase-9 cleavage and Bax/Bcl2 ratio in the hippocampal and cortical neurons, stimulate neurocognitive impairments. Additionally, altered LC3-II/I and P62/SQSTM1, p-mTOR, p-AMPK1 and p-ULK1 levels and dysregulated autophagosome-lysosome fusion decrease neuronal and glial energy homeostasis. The therapies and procedures for attenuating sepsis-induced brain damage include early resuscitation, cerebral blood flow autoregulation, implantable electric vagus nerve stimulation, antioxidants, statins, glucocorticoids, neuroimmune axis modulators and PKCδ inhibitors. The current review enumerates the pathophysiology of sepsis-induced brain damage, its diagnosis, the role of critical inducers and mediators and, ultimately, therapeutic measures attenuating cerebrovascular degeneration.

Modulation of microglial phenotypes improves sepsis-induced hippocampus-dependent cognitive impairments and decreases brain inflammation in an animal model of sepsis

BACKGROUND

In order to modulate microglial phenotypes in vivo, M1 microglia were depleted by administration of gadolinium chloride and the expression of M2 microglia was induced by IL-4 administration in an animal model of sepsis to better characterize the role of microglial phenotypes in sepsis-induced brain dysfunction.

METHODS

Wistar rats were submitted to sham or cecal ligation and perforation (CLP) and treated with IL-4 or GdCl3. Animals were submitted to behavioral tests 10 days after surgery. In a separated cohort of animals at 24 h, 3 and 10 days after surgery, hippocampus was removed and cytokine levels, M1/M2 markers and CKIP-1 levels were determined.

RESULTS

Modulation of microglia by IL-4 and GdCl3 was associated with an improvement in long-term cognitive impairment. When treated with IL-4 and GdCl3, the reduction of pro-inflammatory cytokines was apparent in almost all analyzed time points. Additionally, CD11b and iNOS were increased after CLP at all time points, and both IL-4 and GdCl3 treatments were able to reverse this. There was a significant decrease in CD11b gene expression in the CLP+GdCl3 group. IL-4 treatment was able to decrease iNOS expression after sepsis. Furthermore, there was an increase of CKIP-1 in the hippocampus of GdCl3 and IL-4 treated animals 10 days after CLP induction.

CONCLUSIONS

GdCl3 and IL-4 are able to manipulate microglial phenotype in an animal models of sepsis, by increasing the polarization toward an M2 phenotype IL-4 and GdCl3 treatment was associated with decreased brain inflammation and functional recovery.

Qiang Xin 1 Formula Suppresses Excessive Pro-Inflammatory Cytokine Responses and Microglia Activation to Prevent Cognitive Impairment and Emotional Dysfunctions in Experimental Sepsis

Sepsis commonly leads to acute and long-term cognitive and affective impairments which are associated with increased mortality in patients. Neuroinflammation characterized by excessive cytokine release and immune cell activation underlies the behavioral changes associated with sepsis. We previously reported that the administration of a traditional Chinese herbal Qiang Xin 1 (QX1) formula improves survival in septic mice. This study was performed to better understand the effects and the mechanisms of QX1 formula treatment on behavioral changes in a preclinical septic model induced by cecal ligation and puncture. Oral administration of QX1 formula significantly improved survival, alleviated overall cognitive impairment and emotional dysfunction as assessed by the Morris water maze, novel object recognition testing, elevated plus maze and open field testing in septic mice. QX1 formula administration dramatically inhibited short and long-term excessive pro-inflammatory cytokine production both peripherally and centrally, and was accompanied by diminished microglial activation in septic mice. Biological processes including synaptic transmission, microglia cell activation, cytokine production, microglia cell polarization, as well as inflammatory responses related to signaling pathways including the MAPK signaling pathway and the NF-κB signaling pathway were altered prominently by QX1 formula treatment in the hippocampus of septic mice. In addition, QX1 formula administration decreased the expression of the M1 phenotype microglia gene markers such as Cd32, Socs3, and Cd68, while up-regulated M2 phenotype marker genes including Myc, Arg-1, and Cd206 as revealed by microarray analysis and Real-time PCR. In conclusion, QX1 formula administration attenuates cognitive deficits, emotional dysfunction, and reduces neuroinflammatory responses to improve survival in septic mice. Diminished microglial activation and altered microglial polarization are involved in the neuroprotective mechanism of QX1 formula.

Sickness Behavior Score Is Associated with Neuroinflammation and Late Behavioral Changes in Polymicrobial Sepsis Animal Model

The use of reliable scores is a constant development in critical illness. According to Sepsis-3 consensus, the use of Sequential Organ Failure Assessment (SOFA) score of 2 or more is associated with a higher mortality of sepsis patients. In experimental research, due murine animal model limitations, the use of a score systems can be an alternative to assess sepsis severity. In this work, we suggest a sickness behavior score (SBS) that uses physiological variables to assess sepsis severity and mortality. Animals were evaluated daily by the presence of six indicators of sickness behavior: temperature alteration, preference of water/sucrose, liquid intake, food intake, body weight, and movimentation. Male adult Wistar rats were evaluated daily after sepsis induction by cecal ligation and puncture (CLP) or laparotomy only (sham) for determination of SBS. Oxidative stress, IL-6, and HPA axis markers (corticosterone and adrenal gland weight) were evaluated 24 h after CLP to determine the correlation with the acute SBS and neuroinflammation. Also, BDNF and four cognitive behavioral tests were correlated with the chronic SBS, i.e., sum of 8 days after surgery. In result, septic rats presented higher SBS than sham animals. Sepsis severity markers were associated with acute and chronic SBS. Also, SBS was negative correlated with the cognitive tests. In conclusion, SBS shows to be reliable score to predict sepsis severity and mortality. The use of score system provides the analysis of global sickness behavior, beyond evaluation of each parameter individually.

Characterization and modulation of microglial phenotypes in an animal model of severe sepsis

We aim to characterize the kinetics of early and late microglial phenotypes after systemic inflammation in an animal model of severe sepsis and the effects of minocycline on these phenotypes. Rats were subjected to CLP, and some animals were treated with minocycline (10 ug/kg) by i.c.v. administration. Animals were killed 24 hours, 5, 10 and 30 days after sepsis induction, and serum and hippocampus were collected for subsequent analyses. Real‐time PCR was performed for M1 and M2 markers. TNF‐α, IL‐1β, IL‐6, IL‐10, CCL‐22 and nitrite/nitrate levels were measured. Immunofluorescence for IBA‐1, CD11b and arginase was also performed. We demonstrated that early after sepsis, there was a preponderant up‐regulation of M1 markers, and this was not switched to M2 phenotype markers later on. We found that up‐regulation of both M1 and M2 markers co‐existed up to 30 days after sepsis induction. In addition, minocycline induced a down‐regulation, predominantly, of M1 markers. Our results suggest early activation of M1 microglia that is followed by an overlap of both M1 and M2 phenotypes and that the beneficial effects of minocycline on sepsis‐associated brain dysfunction may be related to its effects predominantly on the M1 phenotype.

Age and Sex Influence the Hippocampal Response and Recovery Following Sepsis

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

Fish oil-rich lipid emulsion modulates neuroinflammation and prevents long-term cognitive dysfunction after sepsis

OBJECTIVES

Sepsis is a severe organic dysfunction caused by an infection that affects the normal regulation of several organ systems, including the central nervous system. Inflammation and oxidative stress play crucial roles in the development of brain dysfunction in sepsis. The aim of this study was to determine the effect of a fish oil (FO)-55-enriched lipid emulsion as an important anti-inflammatory compound on brain dysfunction in septic rats.

METHODS

Wistar rats were subjected to sepsis by cecal ligation and perforation (CLP) or sham (control) and treated orally with FO (600 µL/kg after CLP) or vehicle (saline; sal). Animals were divided into sham+sal, sham+FO, CLP+sal and CLP+FO groups. At 24 h and 10 d after surgery, the hippocampus, prefrontal cortex, and total cortex were obtained and assayed for levels of interleukin (IL)-1β and IL-10, blood-brain barrier permeability, nitrite/nitrate concentration, myeloperoxidase activity, thiobarbituric acid reactive species formation, protein carbonyls, superoxide dismutase and catalase activity, and brain-derived neurotrophic factor levels. Behavioral tasks were performed 10 d after surgery.

RESULTS

FO reduced BBB permeability in the prefrontal cortex and total cortex of septic rats, decreased IL-1β levels and protein carbonylation in all brain structures, and diminished myeloperoxidase activity in the hippocampus and prefrontal cortex. FO enhanced brain-derived neurotrophic factor levels in the hippocampus and prefrontal cortex and prevented cognitive impairment.

CONCLUSIONS

FO diminishes the negative effect of polymicrobial sepsis in the rat brain by reducing inflammatory and oxidative stress markers.

Long-Term Cognitive Outcomes After Sepsis: a Translational Systematic Review

Sepsis is systemic inflammatory response syndrome with a life-threatening organ dysfunction that is caused by an unbalanced host immune response in an attempt to eliminate invasive microorganisms. We posed questions, "Does sepsis survivor patients have increased risk of neuropsychiatric manifestations?" and "What is the mechanism by which sepsis induces long-term neurological sequelae, particularly substantial cognitive function decline in survivor patients and in pre-clinical sepsis models?" The studies were identified by searching PubMed/MEDLINE (National Library of Medicine), PsycINFO, EMBASE (Ovid), LILACS (Latin American and Caribbean Health Sciences Literature), IBECS (Bibliographical Index in Spanish in Health Sciences), and Web of Science databases for peer-reviewed journals that were published until January 2018. A total of 3555 papers were included in the primary screening. After that, 130 articles were selected for the study. A number of pre-clinical studies have shown an auto amplification of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β, and IL-6 in the first few hours after sepsis induction, also increased blood-brain barrier permeability, elevated levels of matrix metalloproteinases, increased levels of damage-associated molecular patterns were demonstrated. In addition, the rodents presented long-term cognitive impairment in different behavioral tasks that were prevented by blocking the mechanism of action of these inflammatory mediators. Clinical studies have showed that sepsis survivors presented increased bodily symptoms such as fatigue, pain, visual disturbances, gastrointestinal problems, and neuropsychiatric problems compared to before sepsis. Sepsis leaves the survivors with an aftermath of physiological, neuropsychiatric, and functional impairment. Systematic review registration: CRD42017071755.

CD40-CD40 Ligand Pathway is a Major Component of Acute Neuroinflammation and Contributes to Long-term Cognitive Dysfunction after Sepsis

Sepsis-associated encephalopathy (SAE) is associated with an increased rate of morbidity and mortality. It is not understood what the exact mechanism is for the brain dysfunction that occurs in septic patients, but brain inflammation and oxidative stress are a possible theory. Such events can occur through the alteration of molecules that perpetuate the inflammatory response. Thus, it is possible to postulate that CD40 may be involved in this process. The aim of this work is to evaluate the role of CD40-CD40L pathway activation in brain dysfunction associated with sepsis in an animal model. Microglia activation induces the upregulation of CD40-CD40L, both in vitro and in vivo. The inhibition of microglia activation decreases levels of CD40-CD40L in the brain and decreases brain inflammation, oxidative damage and blood brain barrier dysfunction. Despite this, anti-CD40 treatment does not improve mortality in this model. However, it is able to improve long-term cognitive impairment in sepsis survivors. In conclusion, there is a major involvement of the CD40-CD40L signaling pathway in long-term brain dysfunction in an animal model of sepsis.

The role of microglia activation in the development of sepsis-induced long-term cognitive impairment

Oxidative stress and inflammation is likely to be a major step in the development of sepsis-associated encephalopathy (SAE) and long-term cognitive impairment. To date, it is not known whether brain inflammation and oxidative damage are a direct consequence of systemic inflammation or whether these events are driven by brain resident cells, such as microglia. Therefore, the aim of this study is to evaluate the effect of minocycline on behavioral and neuroinflammatory parameters in rats submitted to sepsis. Male Wistar rats were subjected to sepsis by cecal ligation and puncture (CLP). The animals were divided into sham-operated (Sham+control), sham-operated plus minocycline (sham+MIN), CLP (CLP+control) and CLP plus minocycline (CLP+MIN) (100 μg/kg, administered as a single intracerebroventricular (ICV) injection). Some animals were killed 24h after surgery to assess the breakdown of the blood brain barrier, cytokine levels, oxidative damage to lipids (TBARS) and proteins in the hippocampus. Some animals were allowed to recover for 10 days when step-down inhibitory avoidance and open-field tasks were performed. Treatment with minocycline prevented an increase in markers of oxidative damage and inflammation in the hippocampus after sepsis. This was associated with an improvement in long-term cognitive performance. In conclusion, we demonstrated that the inhibition of the microglia by an ICV injection of minocycline was able to decrease acute brain oxidative damage and inflammation as well as long-term cognitive impairment in sepsis survivors.