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.

Blood-brain barrier permeability in the ischemic stroke: An update

Stroke is the second leading cause of death globally and the major cause of long-term disability. Among the types of strokes, ischemic stroke, which occurs due to obstruction of blood vessels responsible for cerebral irrigation, is considered the most prevalent, accounting for approximately 86 % of all stroke cases. This interruption of blood supply leads to a critical pathophysiological mechanism, including oxidative stress and neuroinflammation which are responsible for structural alterations of the blood-brain barrier (BBB). The increased BBB permeability associated with cerebral ischemia-reperfusion may contribute to a worse outcome after stroke. Thus, this narrative review aims to update the pathophysiological mechanisms involved in the increase in BBB permeability and to list the possible therapeutic strategies.

The role of intestinal microbiota on pre-eclampsia: Systematic review and meta-analysis

AIM

To investigate differences between gut microbiota diversity and composition of healthy pregnant women and women with pre-eclampsia (PE).

METHODS AND RESULTS

This is a systematic review and meta-analysis of the literature, in which the terms "pre-eclampsia", "gastrointestinal microbiome" and "pregnant women" were used to search MEDLINE (PubMed), BVS (LILACS and others), Embase (Elsevier) and Cochrane Library, including observational studies and case-control that investigated changes in the gut microbiota during pregnancy. Six studies were included, with 479 pregnant women. A significantly lower gut microbiota alpha diversity measured as the Shannon index was found in pregnant women with PE in comparison with healthy controls (SMD: -0.47; 95 %IC: -0.77 to -0.18; P = 0.02; I2 = 0 %; three studies, 179 participants), while no significant differences were found in the relative abundance of Bacteroidetes, Firmicutes, Actinobacteria, and Proteobacteria, despite significant differences reported in the individual studies.

CONCLUSION

Pregnant women with PE have lower gut microbiome diversity, however, there is insufficient evidence to determine whether there are changes in gut microbiota composition.

SIGNIFICANCE AND IMPACT OF THE STUDY

The gut microbiota can be a new treatment target to try to prevent changes in maternal bacterial proportions, aiming to reduce complications during pregnancy.

NLRP3 inflammasome activation increases brain oxidative stress after transient global cerebral ischemia in rats

Pupurpose of the study: Oxidative stress has been reported to be an important mechanism for brain damage following ischemic stroke. Recently, the involvement of cytosolic receptors capable of forming protein complexes called inflammasomes has been demonstrated to perpetuate oxidative stress. Herein, we report the effect of NLRP3 inhibition with MCC950 on brain oxidative stress in an animal model of transient global cerebral ischemia.Materials and methods: Male Wistar rats received an intracerebroventricularly (icv) injection of MCC950 (140 ng/kg) or saline and were subjected to sham procedure or ischemia/reperfusion (I/R). Twenty-four hours after I/R, myeloperoxidase (MPO) activity, nitrite/nitrate (N/N) concentration, lipid peroxidation, protein carbonyls formation, superoxide dismutase (SOD) and catalase (CAT) activity were determined in the prefrontal cortex, hippocampus, cortex, cerebellum and striatum. Results: After I/R, MPO activity increased in the prefrontal cortex, hippocampus, cortex and cerebellum and N/N concentration elevated in the prefrontal cortex, hippocampus and cortex, while MCC950 decreased this level except in hippocampus. After I/R, lipid peroxidation enhanced in the prefrontal cortex and cerebellum and increased the oxidative protein damage in both structures and hippocampus. MCC950 decreased lipid peroxidation in the prefrontal cortex and decreased protein oxidative damage in all brain structures except in the striatum. SOD activity decreased in the cortex after I/R and MCC950 reestablished these levels. CAT activity decreased in the prefrontal cortex, hippocampus and cerebellum after I/R and MCC950 reestablished these levels in the prefrontal cortex.Conclusion: Our data provide novel demonstration that inhibiting NLRP3 activation with MCC950 reduces brain oxidative damage after cerebral I/R in rats.

Folic acid alleviates the blood brain barrier permeability and oxidative stress and prevents cognitive decline in sepsis-surviving rats

Sepsis is a complication of an infection which imbalance the normal regulation of several organ systems, including the central nervous system (CNS). Evidence points towards inflammation and oxidative stress as major steps associated with brain dysfunction in sepsis. Thus, we investigated the folic acid (FA) effect as an important antioxidant compound on acute brain dysfunction in rats and long term cognitive impairment and survival. Wistar rats were subjected to sepsis by cecal ligation and perforation (CLP) or sham (control) and treated orally with FA (10 mg/kg after CLP) or vehicle (veh). Animals were divided into sham + veh, sham + FA, CLP + veh and CLP + FA groups. Twenty-four hours after surgery, the hippocampus and prefrontal cortex were obtained and assayed for levels of blood brain barrier (BBB) permeability, nitrite/nitrate concentration, myeloperoxidase (MPO) activity, thiobarbituric acid reactive species (TBARS) formation and protein carbonyls. Survival was performed during 10 days after surgery and memory was evaluated. FA reduced BBB permeability, MPO activity in hippocampus and pre frontal cortex in 24 h and lipid peroxidation in hippocampus and improves the survival rate after sepsis. Long term cognitive improvement was verified with FA in septic rats compared with CLP + veh. Our data demonstrates that FA reduces the memory impairment in 10 days after sepsis and mortality in part by decreasing BBB permeability and oxidative stress parameters in the brain.

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.

NLRP3 Activation Contributes to Acute Brain Damage Leading to Memory Impairment in Sepsis-Surviving Rats

Sepsis survivors present acute and long-term cognitive impairment and the pathophysiology of neurological dysfunction in sepsis involves microglial activation. Recently, the involvement of cytosolic receptors capable of forming protein complexes called inflammasomes have been demonstrated to perpetuate neuroinflammation. Thus, we investigated the involvement of the NLRP3 inflammasome activation on early and late brain changes in experimental sepsis. Two-month-old male Wistar rats were submitted to the sepsis model by cecal ligation and perforation (CLP group) or laparotomy only (sham group). Immediately after surgery, the animals received saline or NLRP3 inflammasome formation inhibitor (MCC950, 140 ng/kg) intracerebroventricularly. Prefrontal cortex and hippocampus were isolated for cytokine analysis, microglial and astrocyte activation, oxidative stress measurements, nitric oxide formation, and mitochondrial respiratory chain activity at 24 h after CLP. A subset of animals was followed for 10 days for survival assessment, and then behavioral tests were performed. The administration of MCC950 restored the elevation of IL-1β, TNF-α, IL-6, and IL-10 cytokine levels in the hippocampus. NLRP3 receptor levels increased in the prefrontal cortex and hippocampus at 24 h after sepsis, associated with microglial, but not astrocyte, activation. MCC950 reduced oxidative damage to lipids and proteins as well as preserved the activity of the enzyme SOD in the hippocampus. Mitochondrial respiratory chain activity presented variations in both structures studied. MCC950 reduced microglial activation, decreased acute neurochemical and behavioral alteration, and increased survival after experimental sepsis.

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.

Stanniocalcin-1 ameliorates cerebral ischemia by decrease oxidative stress and blood brain barrier permeability

Blood brain barrier (BBB) permeability and oxidative stress have been reported to be important mechanisms for brain damage following ischemic stroke and stanniocalcin-1 (STC-1), a neuroprotective protein, has anti-inflammatory and anti-oxidative stress properties. Herein, we report the effect of STC-1 on BBB permeability and brain oxidative stress after stroke in an animal model. Male Wistar received an intracerebroventricularly injection of human recombinant STC-1 (100 ng/kg) or saline and were subjected to sham procedure or global cerebral ischemia/reperfusion (I/R) model. Six and 24 h after I/R, neurological evaluation was performed; at 24 h brain water content was evaluated in the total brain, and BBB permeability, nitrite/nitrate (N/N) concentration, lipid peroxidation, protein carbonyls formation, superoxide dismutase (SOD) and catalase (CAT) activity were determined in the hippocampus, cortex, prefrontal cortex, striatum and cerebellum. Rats exhibited neurological deficit at 6 and 24 h after I/R and STC-1 reduction at 24 h. After I/R there were an increase of brain water content, BBB permeability in the hippocampus, cortex and pre-frontal cortex and N/N in the hippocampus, and STC-1 decreased this level only in the hippocampus. STC-1 decreased lipid peroxidation in the hippocampus, cortex and prefrontal cortex and protein oxidative damage in the hippocampus and cortex. SOD activity decreased in the hippocampus, cortex and prefrontal cortex after I/R and STC-1 reestablished these levels in the hippocampus and cortex. CAT activity decreased only in the hippocampus and cortex and STC-1 increased the CAT activity in the hippocampus. Our data provide the first experimental demonstration that STC-1 reduced brain dysfunction associated with cerebral I/R in rats, by decreasing BBB permeability and oxidative stress parameters.

Cognitive impairment, blood-brain barrier breakdown, and pro-inflammatory mediators in neonatal Escherichia coli K1 meningitis

Neonatal Escherichia coli meningitis is an important cause of mortality and morbidity in newborns. We evaluated cytokines, oxidative damage/enzymatic defense, BDNF levels, blood-brain barrier (BBB) integrity in the hippocampus of neonatal Wistar rats following E. coli K1 meningitis and subsequent behavioral parameters in adulthood. Neonatal male rats received an intracisternal injection of placebo or E. coli K1 suspension. First: at 6, 12, 24, 48, and 96 h were evaluated cytokines, oxidative damage/enzymatic defense, BDNF levels, and BBB integrity. TNF-α, IL-4, IL-6, IL-10, BDNF, and protein carbonylation were produced mainly in the first 6 to 96 h. Myeloperoxidase, thiobarbituric acid reactive-substances, nitrate/nitrite, and sulfhydryl group were produced at 24 h. Superoxide dismutase decrease in the first 6 h, catalase activity levels did not change and the BBB breakdown at 12 h after meningitis induction. Second: sixty days after meningitis were evaluated behavioural parameters (neonatal rats received antibiotic treatment): habituation to the open-field, step-down inhibitory avoidance, and continuous multiple-trials step down inhibitory avoidance tasks. In the habituation to the open-field and in the step-down inhibitory avoidance tasks there were no differences between training and test session in the meningitis group, demonstrating memory impairment. In the continuous multiple-trials step-down inhibitory avoidance task, there was a significant increase in the number of training trials required to reach the acquisition criterion in the meningitis group when compared to the control group, indicating a learning impairment. Neonatal E. coli K1 meningitis causes learning and memory impairments in adulthood.

Involvement of IL-1β on cognitive impairment after experimental pneumococcal meningitis. (INM1P.432)

Pneumococcal meningitis is associated with high rates of mortality and long-term cognitive impairment. In the current study, we evaluated the effects of an interleukin (IL)-1β receptor antagonist (IL-1Ra) on memory, cytokine, and BDNF levels in experimental pneumococcal meningitis. Adult Wistar rats were divided into four groups: control/saline, control treated with IL-1Ra, meningitis/saline and meningitis treated with IL-1Ra. The animals were killed at 24 h post-infection. In the meningitis/saline group IL-1β and CINC-1 levels increased at 24 h post-infection; however, treatment with IL-1Ra reversed these increases in the hippocampus. In a second experiment, the rats received antibiotic and were subjected to behavioural tasks (open field, step-down inhibitory avoidance and object recognition), cytokine and BDNF levels ten days after meningitis induction. In the open-field task, the meningitis group did not exhibit differences in motor and exploratory activity, indicating habituation memory impairment. The same impairment occurred in the novel object recognition memory and step-down inhibitory avoidance task (aversive memory) in the meningitis group; however, adjuvant treatment with IL-1Ra prevented memory impairment. The IL-4, IL-6, IL-10 and BDNF levels were increased in the meningitis/saline and meningitis/IL-1Ra groups. These findings illustrate a neuroprotective role of IL-1Ra inhibitor and the involvement of IL-1β on cognitive impairment after pneumococcal meningitis.