Intestinal ischemia/reperfusion enhances microglial activation and induces cerebral injury and memory dysfunction in rats

Muscle-derived factor alleviated cognitive impairment caused by intestinal ischemia-reperfusion

Intestinal ischemia/reperfusion (II/R) is a common and grave clinical event, with high morbidity and mortality which can cause cerebral dysfunctions. There are no ideal prevention and treatment measures yet. The present study aimed to determine whether muscle-derived factors can alleviate gut-associated cerebral dysfunctions (GACD) following II/R. We measured the tibialis anterior muscle thickness and irisin levels in patients with and without cognitive dysfunction following cardiopulmonary bypass surgery, calculating the correlation between irisin and cognitive impairment. We found that this protective effect is related to muscle-derived irisin. To elucidate the role of irisin in improving GACD, we knocked out FNDC5 to deplete endogenous irisin and supplemented exogenous irisin. Mechanistic insights into irisin's effects on GACD were investigated using in vivo and in vitro models, incorporating techniques such as transmission electron microscopy, protein docking analysis, gene overexpression, and western blotting. FNDC5/irisin deficiency aggravated cognitive impairments, the pro-inflammation microglia activation, oxidative injury, inflammatory response, neuronal apoptosis and ferroptosis, while recombinant FNDC5/irisin reversed the above changes leading to neurostructural and cognition recovery. Mechanistically, thioredoxin-interacting protein (TXNIP) was activated in the II/R-related neuropathology and was deteriorated in FNDC5/irisin knockout mice. Our results highlight the potential of FNDC5/irisin to slow GACD, providing new insights and potential therapeutic strategies for the prevention and treatment of GACD.

Beyond organ isolation: The bidirectional crosstalk between cerebral and intestinal ischemia-reperfusion injury via microbiota-gut-brain axis

Ischemia-reperfusion injury (IRI) represents a pathophysiological phenomenon of profound clinical relevance that poses considerable threats to patient safety. IRI may manifest in a variety of clinical contexts including, but not limited to, sepsis, organ transplantation, shock, myocardial infarction, cerebral ischemia, and stroke. Critically, IRI exhibits complex interactions across different organs, with effects that surpass mere localized tissue damage. These impacts can amplify damage to both adjacent and remote organs through pathways such as the gut-brain axis and the gut-lung axis, facilitated by intricate signaling mechanisms. Noteworthy is the interaction between gut IRI and brain IRI, which involves sophisticated neuroendocrine, systemic, and immune mechanisms coordinated through the microbiome-gut-brain axis. This review seeks to delve into the intricate interactions between gut and brain IRI, viewed through the lens of the microbiota-gut-brain axis. It aims to assess its translational potential in clinical settings, provide a theoretical foundation for developing relevant therapeutic strategies, and pinpoint novel directions for research.

Assessing the impact of gut microbiota and metabolic products on acute lung injury following intestinal ischemia-reperfusion injury: harmful or helpful?

Ischemia-reperfusion injury (IRI) is a common and clinically significant form of tissue damage encountered in medical practice. This pathological process has been thoroughly investigated across a variety of clinical settings, including, but not limited to, sepsis, organ transplantation, shock, myocardial infarction, cerebral ischemia, and stroke. Intestinal IRI, in particular, is increasingly recognized as a significant clinical entity due to marked changes in the gut microbiota and their metabolic products, often described as the body's "second genome." These changes in intestinal IRI lead to profound alterations in the gut microbiota and their metabolic outputs, impacting not only the pathology of intestinal IRI itself but also influencing the function of other organs through various mechanisms. Notable among these are brain, liver, and kidney injuries, with acute lung injury being especially significant. This review seeks to explore in depth the roles and mechanisms of the gut microbiota and their metabolic products in the progression of acute lung injury initiated by intestinal IRI, aiming to provide a theoretical basis and directions for future research into the treatment of related conditions.

Huangqin decoction attenuates spared nerve injury (SNI)-induced neuropathic pain by modulating microglial M1/M2 polarization partially mediated by intestinal nicotinamide metabolism

BACKGROUND

The incidence of neuropathic pain is progressively increasing over time. The activation of M1-type microglia plays a crucial role in the initiation and progression of neuropathic pain. Huangqin Decoction (HQD) is traditionally used to alleviate dysentery and abdominal pain. However, it remains unclear whether HQD can effectively mitigate neuropathic pain and the underlying mechanisms.

PURPOSE

The present study aims to investigate the impact of HQD on neuropathic pain induced by spared nerve injury (SNI) in mice, and to elucidate whether the analgesic effect of HQD is associated with microglia polarization.

METHODS

The analgesic effect of HQD on SNI mice was investigated through assessments of mechanical pain threshold, thermal pain threshold, cold pain threshold, and motor ability. We elucidated the molecular mechanisms of HQD in alleviating SNI-induced neuropathic pain by focusing on microglia polarization and intestinal metabolite abnormalities. The expression levels of markers associated with microglia polarization (Iba-1, CD68, CD206, iNOS) was detected by immunofluorescence and Western blot, and the levels of inflammatory factors (IL-4, IL-10, IL-6, TNF-α) were assessed by ELISA. UPLC-QTOF-MS metabolomics was utilized to identify differential metabolites in the intestines of SNI mice. We screened the differential metabolites related to microglial polarization by correlation analysis, subsequently nicotinamide was selected for validation in LPS-induced BV-2 cells.

RESULTS

Our findings demonstrated that HQD (20 g/kg) significantly enhanced the mechanical pain threshold, thermal pain threshold, and cold pain threshold, and protected the injured DRG neurons of SNI mice. Moreover, HQD (20 g/kg) obviously suppressed the expression of microglia M1 polarization markers (Iba-1, CD68, iNOS, IL-6, TNF-α), and promoted the expression of microglia M2 polarization markers (CD206, IL-10, IL-4) in the spinal cord of SNI mice. Additionally, HQD (20 g/kg) prominently ameliorated intestinal barrier damage by upregulating Claudin 1 and Occludin expression in the colon of SNI mice. Furthermore, HQD (20 g/kg) rectified 19 metabolite abnormalities in the intestine. Notably, nicotinamide (100 μM), an amide derivative with anti-inflammatory property, effectively suppresses microglia activation and polarization in LPS-induced BV-2 cells by downregulating IL-6 level and CD68 expression while upregulating IL-4 level and CD206 expression.

CONCLUSION

In summary, HQD alleviates neuropathic pain in SNI mice by regulating the activation and polarization of microglia, partially mediated through intestinal nicotinamide metabolism.

EFFECTS OF HYPERBARIC OXYGEN THERAPY ON INTESTINAL ISCHEMIA-REPERFUSION AND ITS MECHANISM

ABSTRACT

Ischemia can cause reversible or irreversible cell or tissue damage, and reperfusion after ischemia not only has no therapeutic effect but also aggravates cell damage. Notably, gut tissue is highly susceptible to ischemia-reperfusion (IR) injury under many adverse health conditions. Intestinal IR (IIR) is an important pathophysiological process in critical clinical diseases. Therefore, it is necessary to identify better therapeutic methods for relieving intestinal ischemia and hypoxia. Hyperbaric oxygenation refers to the intermittent inhalation of 100% oxygen in an environment greater than 1 atm pressure, which can better increase the oxygen level in the tissue and change the inflammatory pathway. Currently, it can have a positive effect on hypoxia and ischemic diseases. Related studies have suggested that hyperbaric oxygen can significantly reduce ischemia-hypoxic injury to the brain, spinal cord, kidney, and myocardium. This article reviews the pathogenesis of IR and the current treatment measures, and further points out that hyperbaric oxygen has a better effect in IR. We found that not only improved hypoxia but also regulated IR induced injury in a certain way. From the perspective of clinical application, these changes and the application of hyperbaric oxygen therapy have important implications for treatment, especially IIR.

Communication Regarding the Myocardial Ischemia/Reperfusion and Cognitive Impairment: A Narrative Literature Review

Coronary artery disease is a prevalent ischemic disease that results in insufficient blood supply to the heart muscle due to narrowing or occlusion of the coronary arteries. Various reperfusion strategies, including pharmacological thrombolysis and percutaneous coronary intervention, have been developed to enhance blood flow restoration. However, these interventions can lead to myocardial ischemia/reperfusion injury (MI/RI), which can cause unpredictable complications. Recent research has highlighted a compelling association between MI/RI and cognitive function, revealing pathophysiological mechanisms that may explain altered brain cognition. Manifestations in the brain following MI/RI exhibit pathological features resembling those observed in Alzheimer's disease (AD), implying a potential link between MI/RI and the development of AD. The pro-inflammatory state following MI/RI may induce neuroinflammation via systemic inflammation, while impaired cardiac function can result in cerebral under-perfusion. This review delves into the role of extracellular vesicles in transporting deleterious substances from the heart to the brain during conditions of MI/RI, potentially contributing to impaired cognition. Addressing the cognitive consequence of MI/RI, the review also emphasizes potential neuroprotective interventions and pharmacological treatments within the MI/RI model. In conclusion, the review underscores the significant impact of MI/RI on cognitive function, summarizes potential mechanisms of cardio-cerebral communication in the context of MI/RI, and offers ideas and insights for the prevention and treatment of cognitive dysfunction following MI/RI.

Stimulator of interferon genes (STING): Key therapeutic targets in ischemia/reperfusion injury

The Stimulator of Interferon Genes (STING) is predominantly expressed in immune cells, including macrophages, natural killer cells, dendritic cells, and T cells, functioning as a pattern recognition receptor. STING activation upon detecting cytosolic DNA released from damaged cells initiates downstream pathways, leading to the production of inflammatory cytokines such as IFNs, IL-6, and TNF-α. Dysregulated STING activation has been implicated in inflammatory and metabolic diseases. Ischemia/reperfusion injury (I/RI) is common in stroke, acute myocardial infarction, organ transplantation, and surgeries for certain end-stage diseases. Recent studies suggest that STING could be a novel therapeutic target for I/RI treatment. In this review, we provide a concise overview of the cGAS-STING signaling pathway's general functions and summarize STING's role in I/RI across various organs, including the heart, liver, kidney, and lung. Moreover, we explore potential therapeutic approaches for I/RI by targeting STING.

Protective and therapeutic potential of melatonin against intestinal diseases: updated review of current data based on molecular mechanisms

INTRODUCTION

Intestinal diseases, a leading global cause of mortality and morbidity, carry a substantial socioeconomic burden. Small and large intestines play pivotal roles in gastrointestinal physiology and food digestion. Pathological conditions, such as gut dysbiosis, inflammation, cancer, therapy-related complications, ulcers, and ischemia, necessitate the urgent exploration of safe and effective complementary therapeutic strategies for optimal intestinal health.

AREAS COVERED

This article evaluates the potential therapeutic effects of melatonin, a molecule with a wide range of physiological actions, on intestinal diseases including inflammatory bowel disease, irritable bowel syndrome, colon cancer, gastric/duodenal ulcers and other intestinal disorders.

EXPERT OPINION

Due to anti-inflammatory and antioxidant properties as well as various biological actions, melatonin could be a therapeutic option for improving digestive disorders. However, more researches are needed to fully understand the potential benefits and risks of using melatonin for digestive disorders.

Tissue-derived extracellular vesicles: Isolation, purification, and multiple roles in normal and tumor tissues

Extracellular vesicles (EVs) are particles released from cells, and their lipid bilayer membrane encloses large amounts of bioactive molecules that endow EVs with intercellular or inter-tissue communicational abilities. Tissue-derived extracellular vesicles (Ti-EVs) are EVs directly separated from the interstitial space of tissue. They could better reflect the actual physiological or pathological state of the tissue microenvironment compared with cell line-derived EVs and biofluid EVs, indicating their potential roles in elucidating the underlying mechanism of pathogenesis and guiding the diagnosis, therapeutic targeting, and cell-free treatment of diseases. However, there have been a relatively limited number of investigations of Ti-EVs. In this review, we have summarized general procedures for Ti-EVs isolation, as well as some caveats with respect to operations after the isolation step, such as purification and storage. In addition, we have also briefly concluded the current research trends on EVs from various normal and tumor tissues, aiming to cast new light on the future research direction of Ti-EVs.

Gut-Derived Exosomes Induce Liver Injury After Intestinal Ischemia/Reperfusion by Promoting Hepatic Macrophage Polarization

Liver injury induced by intestinal ischemia/reperfusion (I/R) is accompanied by the polarization of Kupffer cells, which are specialized macrophages located in the liver. However, the causes of hepatic macrophage polarization after intestinal I/R remain unknown. This study investigated whether gut-derived exosomes contribute to the pathogenesis of liver injury triggered by intestinal I/R in a murine model and explored the underlying mechanisms. Intestinal I/R models were established by temporally clamping the superior mesenteric arteries of mice. Exosomes were isolated from the intestinal tissue of mice that underwent intestinal I/R or sham surgery according to a centrifugation-based protocol. Exosomes were co-cultured with RAW 264.7 macrophages or injected intravenously in mice. Liposomal clodronate was administered intraperitoneally to deplete the macrophages. Macrophage polarization was determined by flow cytometry, immunohistochemistry, and quantitative polymerase chain reaction. Liver injury was assessed by histological morphology and increased serum aspartate aminotransferase and alanine aminotransferase levels. Exosomes from mice intestines subjected to I/R (IR-Exo) promoted macrophage activation in vitro. Intravenous injection of IR-Exo caused hepatic M1 macrophage polarization and led to liver injury in mice. Depleting macrophages ameliorated liver injury caused by intestinal I/R or the injection of IR-Exo. Furthermore, inhibiting exosome release improved intestinal injury, liver function, and survival rates of mice subjected to intestinal I/R. Our study provides evidence that gut-derived exosomes induce liver injury after intestinal I/R by promoting hepatic M1 macrophage polarization. Inhibition of exosome secretion could be a therapeutic target for preventing hepatic impairment after intestinal I/R.

The role of AMPK-Sirt1-autophagy pathway in the intestinal protection process by propofol against regional ischemia/reperfusion injury in rats

Intestinal ischemia/reperfusion (II/R) is a clinical event associated with high morbidity and mortality. AMP-activated protein kinase (AMPK), a central cellular energy sensor, is associated with oxidative stress and inflammation. However, whether the AMPK is involved in the II/R-induced intestinal injury and the underlying mechanism is yet to be elucidated. Propofol has a protective effect on organs; yet, its specific mechanism of action remains unclear. This study explored the role of the AMPK-Sirt1-autophagy pathway in intestinal injury, and whether propofol could reduce intestinal injury and investigated the mechanisms in a rat model of II/R injury as well as a cell model (IEC-6 cells) of hypoxia/reoxygenation (H/R). Propofol, AMPK agonist (AICAR) and AMPK inhibitor (Compound C) were then administered, respectively. The histopathological changes, cell viability and apoptosis were detected. Furthermore, the levels of proinflammatory factors, the activities of oxidative stress, diamine oxidase, and signaling pathway were also analyzed. The results demonstrated that the AMPK-Sirt1-autophagy pathway of intestine was activated after II/R or H/R. Propofol could further activate the pathway, which reduced intestinal injury, inhibited apoptosis, reversed inflammation and oxidative stress, and improved the 24-hour survival rate in II/R rats in vivo, and attenuated H/R-induced IEC-6 cell injury, oxidative stress, and apoptosis in vitro, as fine as changes in AICAR treatment. Compound C abrogated the protective effect of propofol on II/R and H/R-induced injury. These results suggested a crucial effect of AMPK on the mechanism of intestinal injury and might provide a new insight into the mechanism of propofol reducing II/R injury.

Contribution of P2X purinergic receptor in cerebral ischemia injury

The development of cerebral ischemia involves brain damage and abnormal changes in brain function, which can cause neurosensory and motor dysfunction, and bring serious consequences to patients. P2X purinergic receptors are expressed in nerve cells and immune cells, and are mainly expressed in microglia. The P2X4 and P2X7 receptors in the P2X purinergic receptors play a significant role in regulating the activity of microglia. Moreover, ATP-P2X purine information transmission is involved in the progression of neurological diseases, including the release of pro-inflammatory factors, driving factors and cytokines after cerebral ischemia injury, inducing inflammation, and aggravating cerebral ischemia injury. P2X receptors activation can mediate the information exchange between microglia and neurons, induce neuronal apoptosis, and aggravate neurological dysfunction after cerebral ischemia. However, inhibiting the activation of P2X receptors, reducing their expression, inhibiting the activation of microglia, and has the effect of protecting nerve function. In this paper, we discussed the relationship between P2X receptors and nervous system function and the role of microglia activation inducing cerebral ischemia injury. Additionally, we explored the potential role of P2X receptors in the progression of cerebral ischemic injury and their potential pharmacological targets for the treatment of cerebral ischemic injury.

Peripheral interleukin-6-associated microglial QUIN elevation in basolateral amygdala contributed to cognitive dysfunction in a mouse model of postoperative delirium

BACKGROUND

Developing effective approaches for postoperative delirium has been hampered due to the lack of a pathophysiologically similar animal model to offer insights into the pathogenesis. The study, therefore, aimed to develop a delirium-like mouse model and explore the underlying mechanism.

METHODS

The three cycles of 10-min clamp following 5-min reopening of the superior mesenteric artery (SMA) were performed in adult male C57BL/6 mice to induce a delirium-like phenotype. Composite Z score calculated based on the results of Open Field, Y Maze and Buried Food Tests was employed to assess the delirium phenotype in mice. Microglia activities were monitored by immunofluorescence staining and comprehensive morphological analysis. Systemic administration of minocycline (MINO), IL-6 antibody or IL-6 neutralizing antibody, was applied to manipulate microglia. The expressions of Indoleamine 2,3-dioxygenase-1 (IDO-1) and quinolinic acid (QUIN) were examined by RT-PCR and High-Performance Liquid Chromatography/Mass Spectrometry, respectively. Cytokines were measured using fluorescence activated cell sorting method.

RESULTS

The repeated ischemia/reperfusion (I/R) surgery caused significant anxiety (P < 0.05) and cognition decline in working memory and orientation (P < 0.05) in mice at postoperative 24 h. The composite Z score, indicating an overall disturbance of brain function, fluctuated over 24 h after I/R surgery (P < 0.001). Immunofluorescent staining showed that the percentage of microglia in the basolateral amygdala (BLA) (P < 0.05) was reactivated after I/R surgery and was negatively correlated with dwell time at Y maze (R = -0.759, P = 0.035). Inhibiting microglia activities by MINO reduced QUIN productions (P < 0.01) that improved cognitive deficits (P < 0.05). The peripheral IL-6 might cause IL-6 elevation in the BLA. Systemic administration of IL-6 antibodies suppressed I/R-induced IL-6 elevations (P < 0.05), microglial reactivations (P < 0.05), IDO-1 expressions (P < 0.01), and neuroactive metabolite QUIN productions (P < 0.05) in the BLA, resulting in a recovery of cognitive deficits (P < 0.05). Injection of IL-6 exerted opposite effects.

CONCLUSION

The repeated intestinal I/R surgery-induced mouse model is a simple and reproducible one of postoperative delirium. Peripheral IL-6-associated microglial QUIN elevations in the BLA contributed to cognitive dysfunction in the model of postoperative delirium.

Dexmedetomidine Ameliorated Cognitive Dysfunction Induced by Intestinal Ischemia Reperfusion in Mice with Possible Relation to the Anti-inflammatory Effect Through the Locus Coeruleus Norepinephrine System

Cognitive impairment is a common central nervous system complication that occurs following surgery or organs damage outside the nervous system. Neuroinflammation plays a key role in the molecular mechanisms of cognitive impairment. Dexmedetomidine alleviates neuroinflammation and reduces cognitive dysfunction incidence; however, the mechanism by which dexmedetomidine alleviates cognitive dysfunction remains unclear. This study evaluated the effect of dexmedetomidine on attenuation of early cognitive impairment induced by intestinal ischemia–reperfusion in mice and examined whether the locus coeruleus norepinephrine (LCNE) system participates in the anti-inflammatory effect of dexmedetomidine. The superior mesenteric artery was clamped for 45 min to induce intestinal ischemia reperfusion injury. Dexmedetomidine alone or combined with DSP-4, a selective locus coeruleus noradrenergic neurotoxin, was used for pretreatment. Postoperative cognition was assessed using the Morris water maze. Serum and hippocampal levels of IL-1β, TNF-α, norepinephrine (NE), and malondialdehyde (MDA) were assessed by enzyme-linked immunosorbent assay. Immunofluorescence, immunohistochemistry, and hematoxylin and eosin staining were used to evaluate the expression of tyrosine hydroxylase (TH) in the locus coeruleus, hippocampal microglia, and intestinal injury. Pretreatment with dexmedetomidine alleviated intestinal injury and decreased the serum and hippocampal levels of NE, IL-1β, TNF-α, and MDA at 24 h after intestinal ischemia reperfusion, decreased TH-positive neurons in the locus coeruleus, and ameliorated cognitive impairment. Similarly, DSP-4 pre-treatment alleviated neuroinflammation and improved cognitive function. Furthermore, α2-adrenergic receptor antagonist atipamezole or yohimbine administration diminished the neuroprotective effects and improved cognitive function with dexmedetomidine. Therefore, dexmedetomidine attenuated early cognitive dysfunction induced by intestinal ischemia–reperfusion injury in mice, which may be related to its anti-inflammatory effects through the LCNE system.

Thioredoxin-Interacting Protein (TXNIP) Knockdown Protects against Sepsis-Induced Brain Injury and Cognitive Decline in Mice by Suppressing Oxidative Stress and Neuroinflammation

Sepsis-associated encephalopathy (SAE) is linked to increased morbidity and mortality rates in patients with sepsis. Increased cytokine production and neuronal apoptosis are implicated in the pathogenesis of the SAE. Neuroinflammation plays a major role in sepsis-induced brain injury. Thioredoxin-interacting protein (TXNIP), an inhibitor of thioredoxin, is associated with oxidative stress and inflammation. However, whether the TXNIP is involved in the sepsis-induced brain injury and the underlying mechanism is yet to be elucidated. Therefore, the present study was aimed at elucidating the effects of TXNIP knockdown on sepsis-induced brain injury and cognitive decline in mice. Lipopolysaccharide (LPS) was injected intraperitoneally to induce sepsis brain injury in mice. The virus-carrying control or TXNIP shRNA was injected into the lateral ventricle of the brain 4 weeks before the LPS treatment. The histological changes in the hippocampal tissues, encephaledema, and cognitive function were detected, respectively. Also, the 7-day survival rate was recorded. Furthermore, the alterations in microglial activity, oxidative response, proinflammatory factors, apoptosis, protein levels (TXNIP and NLRP3 inflammasome), and apoptosis were examined in the hippocampal tissues. The results demonstrated that the TXNIP and NLRP3 inflammasome expression levels were increased at 6, 12, and 24 h post-LPS injection. TXNIP knockdown dramatically ameliorated the 7-day survival rate, cognitive decline, brain damage, neuronal apoptosis, and the brain water content, inhibited the activation of microglia, downregulated the NLRP3/caspase-1 signaling pathway, and reduced the oxidative stress and the neuroinflammatory cytokine levels at 24 h post-LPS injection. These results suggested a crucial effect of TXNIP knockdown on the mechanism of brain injury and cognitive decline in sepsis mice via suppressing oxidative stress and neuroinflammation. Thus, TXNIP might be a potential therapeutic target for SAE patients.

Lactobacillus murinus alleviate intestinal ischemia/reperfusion injury through promoting the release of interleukin-10 from M2 macrophages via Toll-like receptor 2 signaling

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury has high morbidity and mortality rates. Gut microbiota is a potential key factor affecting intestinal I/R injury. Populations exhibit different sensitivities to intestinal I/R injury; however, whether this interpopulation difference is related to variation in gut microbiota is unclear. Here, to elucidate the interaction between the gut microbiome and intestinal I/R injury, we performed 16S DNA sequencing on the preoperative feces of C57BL/6 mice and fecal microbiota transplantation (FMT) experiments in germ-free mice. The transwell co-culture system of small intestinal organoids extracted from control mice and macrophages extracted from control mice or Toll-like receptor 2 (TLR2)-deficient mice or interleukin-10 (IL-10)-deficient mice were established separately to explore the potential mechanism of reducing intestinal I/R injury.

RESULTS

Intestinal I/R-sensitive (Sen) and intestinal I/R-resistant (Res) mice were first defined according to different survival outcomes of mice suffering from intestinal I/R. Fecal microbiota composition and diversity prior to intestinal ischemia differed between Sen and Res mice. The relative abundance of Lactobacillus murinus (L. murinus) at the species level was drastically higher in Res than that in Sen mice. Clinically, the abundance of L. murinus in preoperative feces of patients undergoing cardiopulmonary bypass surgery was closely related to the degree of intestinal I/R injury after surgery. Treatment with L. murinus significantly prevented intestinal I/R-induced intestinal injury and improved mouse survival, which depended on macrophages involvement. Further, in vitro experiments indicated that promoting the release of IL-10 from macrophages through TLR2 may be a potential mechanism for L. murinus to reduce intestinal I/R injury.

CONCLUSION

The gut microbiome is involved in the postoperative outcome of intestinal I/R. Lactobacillus murinus alleviates mice intestinal I/R injury through macrophages, and promoting the release of IL-10 from macrophages through TLR2 may be a potential mechanism for L. murinus to reduce intestinal I/R injury. This study revealed a novel mechanism of intestinal I/R injury and a new therapeutic strategy for clinical practice. Video Abstract.

Autophagy-lysosome dysfunction is involved in gastric ischemia-reperfusion injury by promoting microglial activation in the paraventricular nucleus

The hypothalamic paraventricular nucleus (PVN) is a specific center in the brain that regulates gastric mucosal injury following gastric ischemia-reperfusion (GI-R) injury. This study aimed to investigate whether autophagy-lysosome dysfunction in the PVN tissues of GI-R rats is involved in the gastric injury, and the underlying molecular mechanisms. The rat model of GI-R was established by clamping the celiac artery for 30 min and reperfusion for different hours (1, 3, and 6 h). The gastric injury was evaluated by hematoxylin and eosin staining of the stomach and the gastric mucosal index. The autophagy-lysosome dysfunction in the PVN was evaluated by the protein levels of LC3 II and Beclin-1 (markers for autophagosome activity) and the activity of acid phosphatase (a representative lysosomal enzyme). Immunohistochemical staining of ionized calcium-binding adaptor molecule 1 in the PVN was performed to evaluate microglial activation. Reactive oxygen species (ROS) content and phosphorylated γ-aminobutyric acid B receptor (p-GABA_B R) expression in the PVN were also examined. The results revealed that, in GI-R rats, the shorter the reperfusion duration, the more severe the gastric mucosal damage. The autophagy-lysosome dysfunction exhibited by GI-R rats further enhanced microglial activation, ROS production, p-GABA_B R expression, and gastric injury. In addition, activating microglial cells increased ROS production, p-GABA_B R expression, and gastric injury in GI-R rats, while inhibiting microglial activation resulted in the opposite results. Taken together, autophagy-lysosome dysfunction induced by GI-R aggravated the gastric injury by inducing microglia activation.

Dexmedetomidine inhibits mitochondria damage and apoptosis of enteric glial cells in experimental intestinal ischemia/reperfusion injury via SIRT3-dependent PINK1/HDAC3/p53 pathway

BACKGROUND

Intestinal ischemia/reperfusion (I/R) injury commonly occurs during perioperative periods, resulting in high morbidity and mortality on a global scale. Dexmedetomidine (Dex) is a selective α2-agonist that is frequently applied during perioperative periods for its analgesia effect; however, its ability to provide protection against intestinal I/R injury and underlying molecular mechanisms remain unclear.

METHODS

To fill this gap, the protection of Dex against I/R injury was examined in a rat model of intestinal I/R injury and in an inflammation cell model, which was induced by tumor necrosis factor-alpha (TNF-α) plus interferon-gamma (IFN-γ) stimulation.

RESULTS

Our data demonstrated that Dex had protective effects against intestinal I/R injury in rats. Dex was also found to promote mitophagy and inhibit apoptosis of enteric glial cells (EGCs) in the inflammation cell model. PINK1 downregulated p53 expression by promoting the phosphorylation of HDAC3. Further studies revealed that Dex provided protection against experimentally induced intestinal I/R injury in rats, while enhancing mitophagy, and suppressing apoptosis of EGCs through SIRT3-mediated PINK1/HDAC3/p53 pathway in the inflammation cell model.

CONCLUSION

Hence, these findings provide evidence supporting the protective effect of Dex against intestinal I/R injury and its underlying mechanism involving the SIRT3/PINK1/HDAC3/p53 axis.

Neurodevelopmental outcome of patients with congenital gastrointestinal malformations: a systematic review and meta-analysis

AIM

Children with congenital gastrointestinal malformations may be at risk of neurodevelopmental impairment due to challenges to the developing brain, including perioperative haemodynamic changes, exposure to anaesthetics and postoperative inflammatory influences. This study aggregates existing evidence on neurodevelopmental outcome in these patients using meta-analysis.

METHOD

PubMed, Embase and Web of Science were searched for peer-reviewed articles published until October 2019. Out of the 5316 unique articles that were identified, 47 studies met the inclusion criteria and were included. Standardised mean differences (Cohen's d) between cognitive, motor and language outcome of patients with congenital gastrointestinal malformations and normative data (39 studies) or the studies' control group (8 studies) were aggregated across studies using random-effects meta-analysis. The value of (clinical) moderators was studied using meta-regression and diagnostic subgroups were compared.

RESULTS

The 47 included studies encompassed 62 cohorts, representing 2312 patients. Children with congenital gastrointestinal malformations had small-sized cognitive impairment (d=-0.435, p<0.001; 95% CI -0.567 to -0.302), medium-sized motor impairment (d=-0.610, p<0.001; 95% CI -0.769 to -0.451) and medium-sized language impairment (d=-0.670, p<0.001; 95% CI -0.914 to -0.425). Patients with short bowel syndrome had worse motor outcome. Neurodevelopmental outcome was related to the number of surgeries and length of total hospital stay, while no relations were observed with gestational age, birth weight, age and sex.

INTERPRETATION

This study shows that children with congenital gastrointestinal malformations exhibit impairments in neurodevelopmental outcome, highlighting the need for routine screening of neurodevelopment during follow-up.

Gut-Derived Exosomes Mediate Memory Impairment After Intestinal Ischemia/Reperfusion via Activating Microglia

Intestinal ischemia/reperfusion is a grave condition with high morbidity and mortality in perioperative and critical care settings and causes multiple organ injuries beyond the intestine, including brain injury. Exosomes act as intercellular communication carriers by the transmission of their cargo to recipient cells. Here, we investigate whether exosomes derived from the intestine contribute to brain injury after intestinal ischemia/reperfusion via interacting with microglia in the brain. Intestinal ischemia/reperfusion was established in male C57/BL mice by clamping the superior mesenteric artery for 30 min followed by reperfusion. The sham surgery including laparotomy and isolation of the superior mesenteric artery without occlusion was performed as control. Male C57 mouse was intracerebral ventricular injected with intestinal exosomes from mice of intestinal ischemia/reperfusion or sham surgery. Primary microglia were cocultured with intestinal exosomes; HT-22 cells were treated with intestinal exosomes or microglia conditioned media. Intestinal ischemia/reperfusion-induced microglial activation, neuronal loss, synaptic stability decline, and cognitive deficit. Intracerebral ventricular injection of intestinal exosomes from intestinal ischemia/reperfusion mice causes microglial activation, neuronal loss, synaptic stability decline, and cognitive impairment. Microglia can incorporate intestinal exosomes both in vivo and in vitro. Microglia activated by intestinal exosomes increases neuron apoptotic rate and decreases synaptic stability. This study indicates that intestinal exosomes mediate memory impairment after intestinal ischemia/reperfusion via activating microglia. Inhibiting exosome secretion or suppressing microglial activation can be a therapeutic target to prevent memorial impairment after intestinal ischemia/reperfusion.

Sesamin Protects against and Ameliorates Rat Intestinal Ischemia/Reperfusion Injury with Involvement of Activating Nrf2/HO-1/NQO1 Signaling Pathway

Intestinal ischemia-reperfusion (I/R) may induce cell/tissue injuries, leading to multiple organ failure. Based on our preexperiments, we proposed that sesamin could protect against and ameliorate intestinal I/R injuries and related disorders with involvement of activating Nrf2 signaling pathway. This proposal was evaluated using SD intestinal I/R injury rats in vivo and hypoxia/reoxygenation- (H/R-) injured rat small intestinal crypt epithelial cell line (IEC-6 cells) in vitro. Sesamin significantly alleviated I/R-induced intestinal histopathological injuries and significantly reduced serum biochemical indicators ALT and AST, alleviating I/R-induced intestinal injury in rats. Sesamin also significantly reversed I/R-increased TNF-α, IL-6, IL-1β, and MPO activity in serum and MDA in tissues and I/R-decreased GSH in tissues and SOD in both tissues and IEC-6 cells, indicating its anti-inflammatory and antioxidative stress effects. Further, sesamin significantly decreased TUNEL-positive cells, downregulated the increased Bax and caspase-3 protein expression, upregulated the decreased protein expression of Bcl-2 in I/R-injured intestinal tissues, and significantly reversed H/R-reduced IEC-6 cell viability as well as reduced the number of apoptotic cells among H/R-injured IEC-6 cell, showing antiapoptotic effects. Activation of Nrf2 is known to ameliorate tissue/cell injuries. Consistent with sesamin-induced ameliorations of both intestinal I/R injuries and H/R injuries, transfection of Nrf2 cDNA significantly upregulated the expression of Nrf2, HO-1, and NQO1, respectively. On the contrary, either Nrf2 inhibitor (ML385) or Nrf2 siRNA transfection significantly decreased the expression of these proteins. Our results suggest that activation of the Nrf2/HO-1/NQO1 signaling pathway is involved in sesamin-induced anti-inflammatory, antioxidative, and antiapoptotic effects in protection against and amelioration of intestinal I/R injuries.

Tofacitinib protects intestinal epithelial cells against oxygen-glucose deprivation/reoxygenation injury by inhibiting the JAK/STAT3 signaling pathway

The present study aimed to investigate the role and potential mechanism of action of tofacitinib (Tofa) in intestinal ischemia/reperfusion (I/R) injury. The normal rat small intestine epithelial cell line, IEC-6, was used to establish an I/R injury model by inducing oxygen-glucose deprivation/reoxygenation (OGD/R). Cells were divided into the following five groups: Control, OGD/R, OGD/R with 50, 100 and 200 nM Tofa. Following Tofa administration, cell viability was measured using Cell Counting Kit-8 assay and a lactate dehydrogenase detection kit. The expression levels of cell apoptosis-related proteins, Bcl-2, cleaved-caspase-3 and cleaved-caspase-9 were detected using western blot analysis. Additionally, the levels of oxidative stress-related markers, such as reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD), and inflammatory cytokines, TNF-α, IL-6 and IL-1β were assessed using the colorimetric method. Western blot analysis was also used to measure the expression levels of the Janus kinase (JAK)/STAT3 signaling pathway-related proteins, including phosphorylated (p)-JAK1, p-JAK3 and p-STAT3. Subsequently, colivelin, an agonist of the JAK/STAT3 pathway, was used to investigate whether the effects of Tofa on intestinal I/R injury were mediated by this signaling pathway. The results showed that Tofa dose-dependently elevated cell viability compared with that in the OGD/R group. By contrast, Tofa attenuated cell apoptosis, which was coupled with upregulated Bcl-2 expression, downregulated cleaved-caspase-3 and downregulated cleaved-caspase-9 levels, in OGD/R-induced IEC-6 cells. Furthermore, the contents of ROS and MDA were significantly increased following exposure to OGD/R, which were accompanied by the decreased activity of SOD. These effects were reversed following cell treatment with Tofa. Consistently, Tofa intervention reduced the secretion levels of TNF-α, IL-6 and IL-1β in a dose-dependent manner. Additionally, Tofa markedly downregulated the phosphorylation levels of JAK1, JAK3 and STAT3 in OGD/R-induced IEC-6 cells. However, treatment with colivelin markedly reversed the inhibitory effects of Tofa on cell viability, cell apoptosis, oxidative stress and inflammation. Overall, the findings of the present study suggested that Tofa could protect against intestinal I/R injury by inhibiting the JAK/STAT3 signaling pathway, which may hold promise as a therapeutic agent for intestinal I/R injury.

Circulating HMGB1 is elevated in veterans with Gulf War Illness and triggers the persistent pro-inflammatory microglia phenotype in male C57Bl/6J mice

Gulf War Illness (GWI) is a chronic, multi-symptom peripheral and CNS condition with persistent microglial dysregulation, but the mechanisms driving the continuous neuroimmune pathology are poorly understood. The alarmin HMGB1 is an autocrine and paracrine pro-inflammatory signal, but the role of circulating HMGB1 in persistent neuroinflammation and GWI remains largely unknown. Using the LPS model of the persistent microglial pro-inflammatory response, male C57Bl/6J mice injected with LPS (5 mg/kg IP) exhibited persistent changes in microglia morphology and elevated pro-inflammatory markers in the hippocampus, cortex, and midbrain 7 days after LPS injection, while the peripheral immune response had resolved. Ex vivo serum analysis revealed an augmented pro-inflammatory response to LPS when microglia cells were cultured with the 7-day LPS serum, indicating the presence of bioactive circulating factors that prime the microglial pro-inflammatory response. Elevated circulating HMGB1 levels were identified in the mouse serum 7 days after LPS administration and in the serum of veterans with GWI. Tail vein injection of rHMGB1 in male C57Bl/6 J mice elevated TNFα mRNA levels in the liver, hippocampus, and cortex, demonstrating HMGB1-induced peripheral and CNS effects. Microglia isolated at 7 days after LPS injection revealed a unique transcriptional profile of 17 genes when compared to the acute 3 H LPS response, 6 of which were also upregulated in the midbrain by rHMGB1, highlighting a distinct signature of the persistent pro-inflammatory microglia phenotype. These findings indicate that circulating HMGB1 is elevated in GWI, regulates the microglial neuroimmune response, and drives chronic neuroinflammation that persists long after the initial instigating peripheral stimulus.

Dexmedetomidine alleviates neuroinflammation, restores sleep disorders and neurobehavioral abnormalities in rats with minimal hepatic encephalopathy

The occurrence and progress of minimal hepatic encephalopathy (MHE) is closely related to the inflammatory response; however, inflammation contributes to behavioral abnormalities and sleep disorders. Dexmedetomidine has anti-inflammatory effects against various diseases. Whether dexmedetomidine improves MHE and the underlying mechanism is yet unclear. The present study aimed to explore the effects of dexmedetomidine on sleep structure, neurobehavior, and brain morphology of MHE rats and investigate its underlying mechanism. A rat MHE model was established by intraperitoneal injection of thioacetamide (TAA). Dexmedetomidine or yohimbine was administered intraperitoneally to investigate the role of α2 adrenoreceptor in the protection conferred by dexmedetomidine. The 24-h sleep, neurobehavioral changes, the liver function, blood ammonia and morphological changes of the liver and brain were assessed. Also, the microglia, astrocytes, neurons, the expression of pro-inflammatory factors (IL-1β, TNF-α, IL-18), and NLRP3 inflammasomes were detected. The results showed that marked sleep disorders, cognitive impairment, anxiety, abnormal liver function and pathological damage of liver and brain were detected in the MHE rats. The microglia in the prefrontal cortex was highly activated along with the increased expression of pro-inflammatory factors and NLRP3 inflammasomes. Interestingly, dexmedetomidine improved above indicators, however, yohimbine significantly abolished the protection of dexmedetomidine. These findings showed that dexmedetomidine restored the changes in the sleep disorders and neurobehavior in rats and reduced brain damage. The mechanism might be partially related to the activation of α2 adrenergic receptors, reduction of neuroinflammatory response, and inhibition of the activation of microglia and NLRP3/Caspase1 signaling pathway.

Intestinal ischemic reperfusion injury: Recommended rats model and comprehensive review for protective strategies

Intestinal ischemic reperfusion injury (IIRI) is a life-threatening condition with high morbidity and mortality in the clinic. IIRI was induced by intestinal ischemic diseases such as, small bowel transplantation, aortic aneurysm surgery, and strangulated hernias. Although related mechanisms have not been fully elucidated, during the last decade, researches have demonstrated that many factors are crucial in the pathological process, including oxidative stress (OS), epithelial barrier function disorder, and so on. Rats model, as the most applied animal IIRI model, provides specific targets for researches and therapeutic strategies. Moreover, various treatment strategies such as, anti-oxidative stress, anti-apoptosis, and anti-inflammation, have shown promising effects in alleviating IIRI. However, current researches cannot solve the clinical problems of IIRI, and specific treatment strategies are still needed to be exploited. This review focuses on a recommended experimental IIRI rat model and understanding of the involved mechanisms such as, OS, gut bacteria translocation, apoptosis, and necroptosis, aim at providing novel ideas for therapeutic strategies of IIRI.

Microarray Profiling and Functional Identification of LncRNA in Mice Intestinal Mucosa Following Intestinal Ischemia/Reperfusion

BACKGROUND

Intestinal ischemia-reperfusion (I/R) injury is a common clinical event with high mortality, but its mechanism is elusive. Although long noncoding RNAs (lncRNAs) have recently emerged as critical molecules in I/R damage in other organs, the changes in their expression and potential roles in intestinal I/R remain unclear.

METHODS

The expression profiles of both lncRNAs and mRNAs in mouse intestinal mucosa after intestinal I/R were explored by a microarray approach, and their biological functions were elucidated by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Then, some lncRNAs were further verified by qRT-PCR. Based on the coding-noncoding gene coexpression (CNC) network analyses, the role of lncRNA AK089510 in intestinal I/R-induced intestinal mucosa apoptosis was investigated by knockdown assay in vitro.

RESULTS

A total of 3602 aberrantly expressed lncRNAs (1503 upregulated and 2099 downregulated) and 3158 mRNAs (1528 upregulated and 1630 downregulated) were identified. The dysregulated transcripts were enriched in the lipid metabolic process, apoptotic process, reactive oxygen species metabolic process, MAPK, TNF, ErbB, mTOR, and FoxO signaling pathways, and so on. The overexpression of lncRNA AK089510 was validated by qRT-PCR, and the CNC analysis revealed its target mRNAs. AK089510-siRNA reduced Casp6 and Casp7 expression and suppressed intestinal epithelial cell apoptosis after oxygen-glucose deprivation treatment.

CONCLUSIONS

Our study revealed the lncRNA and mRNA expression patterns in mouse intestinal mucosa after intestinal I/R and predicted their potential functions and pathways. We identified AK089510 as a novel lncRNA involved in the apoptosis of intestinal mucosa, advancing our understanding of the molecular mechanisms of intestinal I/R injury.

Selective brain cooling achieves peripheral organs protection in hemorrhagic shock resuscitation via preserving the integrity of the brain-gut axis

Background: Although whole-body cooling has been reported to improve the ischemic/reperfusion injury in hemorrhagic shock (HS) resuscitation, it is limited by its adverse reactions following therapeutic hypothermia. HS affects the experimental and clinical bowel disorders via activation of the brain-gut axis. It is unknown whether selective brain cooling achieves beneficial effects in HS resuscitation via preserving the integrity of the brain-gut axis. Methods: Male Sprague-Dawley rats were bled to hypovolemic HS and resuscitated with blood transfusion followed by retrograde jugular vein flush (RJVF) with 4 °C or 36 °C normal saline. The mean arterial blood pressure, cerebral blood flow, and brain and core temperature were measured. The integrity of intestinal tight junction proteins and permeability, blood pro-inflammatory cytokines, and multiple organs damage score were determined. Results: Following blood transfusion resuscitation, HS rats displayed gut barrier disruption, increased blood levels of pro-inflammatory cytokines, and peripheral vital organ injuries. Intrajugular-based infusion cooled the brain robustly with a minimal effect on body temperature. This brain cooling significantly reduced the HS resuscitation-induced gut disruption, systemic inflammation, and peripheral vital organ injuries in rats. Conclusion: Resuscitation with selective brain cooling achieves peripheral vital organs protection in hemorrhagic shock resuscitation via preserving the integrity of the brain-gut axis.

MiR-23a-5p exacerbates intestinal ischemia-reperfusion injury by promoting oxidative stress via targeting PPAR alpha

MiR-23a-5p is involved in the occurrence and development of some serious diseases, but its effects on intestinal ischemia-reperfusion (II/R) injury is unclear. In this research, the hypoxia/reoxygenation (H/R) model on IEC-6 cells and II/R model in mice were used. The data showed that the ROS level in model group was significantly increased compared with control group. The level of intestinal MPO was increased and serum SOD was decreased in mice compared with sham group. Moreover, the expression levels of miR-23a-5p in model groups were obviously increased in vitro and in vivo, while the expression levels of PPARα, FOXO3α, PGC-1α, Nrf2, CAT, NQO1, HO-1 and SOD2 were significantly decreased. The double luciferase reporter gene assay showed that there was binding site between miR-23a-5p and PPARα. When miR-23a-5p was inhibited or PPARα gene was overexpressed, H/R-caused cell damage was alleviated and ROS level was decreased compared with NC group. PPARα expression level was increased, accompanied by the increased levels of FOXO3α, PGC-1α, Nrf2, CAT, NQO1, HO-1 and SOD2. After enhancing miR-23a-5p expression or silencing PPARα gene, H/R-caused cell damage was further aggravated compared with NC group, and ROS level was increased associated with the decreased levels of FOXO3α, PGC-1α, Nrf2, CAT, NQO1, HO-1 and SOD2. Our study demonstrated that miR-23a-5p exacerbated II/R injury by promoting oxidative stress via targeting PPARα, which should be considered as one new drug target to treat II/R injury.

Ischemia/reperfusion injured intestinal epithelial cells cause cortical neuron death by releasing exosomal microRNAs associated with apoptosis, necroptosis, and pyroptosis

To date, there is no good evidence that intestine epithelial cells (IEC) affected by ischemia/reperfusion (I/R) injury are able to cause cortical neuron injury directly. Additionally, it remains unclear whether the neuronal damage caused by I/R injured IEC can be affected by therapeutic hypothermia (TH, 32 °C). To address these questions, we performed an oxygen–glucose deprivation (OGD) affected IEC-6-primary cortical neuron coculture system under normothermia (37 °C) or TH (32 °C) conditions. It was found that OGD caused hyperpermeability in IEC-6 cell monolayers. OGD-preconditioned IEC-6 cells caused cortical neuronal death (e.g., decreased cell viability), synaptotoxicity, and neuronal apoptosis (evidenced by increased caspase-3 expression and the number of TUNEL-positive cells), necroptosis (evidenced by increased receptor-interacting serine/threonine-protein kinase-1 [RIPK1], RIPK3 and mixed lineage kinase domain-like pseudokinase [MLKL] expression), and pyroptosis (evidenced by an increase in caspase-1, gasdermin D [GSDMD], IL-1β, IL-18, the apoptosis-associated speck-like protein containing a caspase recruitment domain [ASC], and nucleotide oligomerization domain [NOD]-like receptor [NLRP]-1 expression). TH did not affect the intestinal epithelial hyperpermeability but did attenuate OGD-induced neuronal death and synaptotoxicity. We also performed quantitative real-time PCR to quantify the genes encoding 84 exosomal microRNAs in the medium of the control-IEC-6, the control-neuron, the OGD-IEC-6 at 37 °C, the OGD-IEC-6 at 32 °C, the neuron cocultured with OGD-IEC-6 at 37 °C, and the neurons cocultured with OGD-IEC-6 at 32 °C. We found that the control IEC-6 cell s or cortical neurons are able to secrete a basal level of exosomal miRNAs in their medium. OGD significantly up-regulated the basal level of each parameter for IEC-6 cells. As compared to those of the OGD-IEC-6 cells or the control neurons, the OGD-IEC-6 cocultured neurons had significantly higher levels of 19 exosomal miRNAs related to apoptosis, necroptosis, and/or pyroptosis events. Our results identify that I/R injured intestinal epithelium cells can induce cortical neuron death via releasing paracrine mediators such as exosomal miRNAs associated with apoptosis, necroptosis, and/or pyroptosis, which can be counteracted by TH.

Melatonin alleviates intestinal injury, neuroinflammation and cognitive dysfunction caused by intestinal ischemia/reperfusion

Intestinal ischemia/reperfusion (I/R) can cause multiple organ damage with extremely high morbidity and mortality. Melatonin has anti-inflammatory, anti-oxidative and anti-apoptotic effects against various diseases. This study aimed to explore whether melatonin had a protective effect against intestinal I/R-induced neuroinflammation and cognitive dysfunction, and investigate its potential mechanisms. In this study, melatonin was administered to the rats with intestinal I/R, then histological changes in intestine and brain (frontal cortex and hippocampal CA1 area) tissues and cognitive function were detected, respectively. The encephaledema and blood-brain barrier (BBB) permeability were observed. Moreover, the alterations of proinflammatory factors (tumor necrosis factor-α, interleukin-6 and interleukin-1β), oxidative response (malondialdehyde, superoxide dismutase, and reactive oxygen species), apoptosis and proteins associated with inflammation,including Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (Myd88) and phosphorylated nuclear factor kappa beta (NF-κB), and apoptosis (cleaved caspase-3) in brain tissues were examined. Furthermore, the expressions of TLR4, Myd88, and microglial activity were observed by multiple immunofluorescence staining. The results showed that intestinal I/R-induced abnormal neurobehavior and cerebral damage were ameliorated after melatonin treatment, which were demonstrated by improved cognitive dysfunction and aggravated histology. Furthermore, melatonin decreased the levels of proinflammatory factors and oxidative stress in plasma, intestine and brain tissues, attenuated apoptotic cell, and inhibited the expressions of related proteins and the immunoreactivity of TLR4 or Myd88 in microglia in brain tissues. These findings showed that melatonin might relieve neuroinflammation and cognitive dysfunction caused by intestinal I/R, which could be, at least partially, related to the inhibition of the TLR4/Myd88 signaling in microglia.

Hydrogen-Rich Saline Attenuates Acute Lung Injury Induced by Limb Ischemia/Reperfusion via Down-Regulating Chemerin and NLRP3 in Rats

Limb ischemia/reperfusion (LI/R) injury is associated with high morbidity and mortality. The hypothesis of this study is that hydrogen-rich solution could attenuateacute lung injury and improve mortality via chemerin and NLRP3 after LI/R in rats. A rat model of LI/R was performed by clamping the bilateral femoral arteries for 3 h followed by reperfusion. Hydrogen-rich saline (HRS) was administered intraperitoneally (10 mL/kg or 2.5 mL/kg) when the atraumatic micro clips were released. The rats were euthanized at 2 h after reperfusion and then the arterial blood and lung specimens were harvested for further analyses. Meanwhile, survival rate was observed. The results showed that HRS improved the survival rate and attenuated pulmonary edema, injury, and apoptosis. HRS also decreased the levels of tumor necrosis factor-α, interleukin-6, myeloperoxidase and malondialdehyde, and increased the activity of superoxide dismutase in serum and lung after the LI/R event. HRS downregulated the expression of chemerin and NLRP3 in lung. The study demonstrated that chemerin and NLRP3 could serve as important response factors that were involved in the lung injury following LI/R. HRS could significantly attenuate LI/R-mediated acute lung injury, at least in part, by inhibiting the activated chemerin/NLRP3 signaling pathway.

Amelioration of Coagulation Disorders and Inflammation by Hydrogen-Rich Solution Reduces Intestinal Ischemia/Reperfusion Injury in Rats through NF-κB/NLRP3 Pathway

Intestinal ischemia/reperfusion (I/R) injury often causes inflammatory responses and coagulation disorders, which is further promoting the deterioration of the disease. Hydrogen has anti-inflammatory, antioxidative, and antiapoptotic properties against various diseases. However, the effect of hydrogen on coagulation dysfunction after intestinal I/R and the underlying mechanism remains unclear. The purpose of this study was to explore whether hydrogen-rich solution (HRS) could attenuate coagulation disorders and inflammation to improve intestinal injury and poor survival following intestinal I/R. The rat model of intestinal I/R injury was established by clamping the superior mesenteric artery for 90 min and reperfusion for 2 h. HRS (10 or 20 mL/kg) or 20 mL/kg 0.9% normal saline was intravenously injected at 10 min before reperfusion, respectively. The samples were harvested at 2 h after reperfusion for further analyses. Moreover, the survival rate was observed for 24 h. The results showed that HRS improved the survival rate and alleviated serum diamine oxidase activities, intestinal injury, edema, and apoptosis. Interestingly, HRS markedly improved intestinal I/R-mediated coagulation disorders as evidenced by abnormal conventional indicators of coagulation and thromboelastography. Additionally, HRS attenuated inflammatory responses and the elevated tissue factor (TF) and inhibited nuclear factor kappa beta (NF-κB) and nucleotide binding and oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation in peripheral blood mononuclear cells. Moreover, inflammatory factors and myeloperoxidase were closely associated with TF level. This study thus emphasized upon the amelioration of coagulation disorders and inflammation by HRS as a mechanism to improve intestinal I/R-induced intestinal injury and poor survival, which might be partially related to inhibition of NF-κB/NLRP3 pathway.

Enhanced Effect of IL-1β-Activated Adipose-Derived MSCs (ADMSCs) on Repair of Intestinal Ischemia-Reperfusion Injury via COX-2-PGE2 Signaling

Adipose-derived mesenchymal stem cells (ADMSCs) have been used for treating tissue injury, and preactivation enhances their therapeutic effect. This study is aimed at investigating the therapeutic effect of activated ADMSCs by IL-1β on the intestinal ischaemia-reperfusion (IR) injury and exploring potential mechanisms. ADMSCs were pretreated with IL-1β in vitro, and activation of ADMSCs was assessed by α-SMA and COX-2 expressions and secretary function. Activated ADMSCs was transplanted into IR-injured intestine in a mouse model, and therapeutic effect was evaluated. In addition, to explore underlying mechanisms, COX-2 expression was silenced to investigate its role in activated ADMSCs for treatment of intestinal IR injury. When ADMSCs were pretreated with 50 ng/ml IL-1β for 24 hr, expressions of α-SMA and COX-2 were significantly upregulated, and secretions of PGE₂, SDF-1, and VEGF were increased. When COX-2 was silenced, the effect of IL-1β treatment was abolished. Activated ADMSCs with IL-1β significantly suppressed inflammation and apoptosis and enhanced healing of intestinal IR injury in mice, and these effects were impaired by COX-2 silencing. The results of RNA sequencing suggested that compared with the IR injury group activated ADMSCs induced alterations in mRNA expression and suppressed the activation of the NF-κB-P65, MAPK-ERK1/2, and PI3K-AKT pathways induced by intestinal IR injury, whereas silencing COX-2 impaired the suppressive effect of activated ADMSCs on these pathway activations induced by IR injury. These data suggested that IL-1β pretreatment enhanced the therapeutic effect of ADMSCs on intestinal IR injury repairing via activating ADMSC COX-2-PGE₂ signaling axis and via suppressing the NF-κB-P65, MAPK-ERK1/2, and PI3K-AKT pathways in the intestinal IR-injured tissue.

Isolation of extracellular vesicles from intestinal tissue in a mouse model of intestinal ischemia/reperfusion injury

Extracellular vesicles (EVs) are small membranous particles that contribute to intercellular communications. Separating EVs from tissue is still a technical challenge. Here, we present a rigorous method for extracting EVs from intestinal tissue in a mouse intestinal ischemia/reperfusion (I/R) model, and for analyzing their miRNA content. The isolated EVs show a typical cup shape with a size peak of 120-130 nm in diameter, confirmed by TEM and NTA. They also express EV markers such as CD9, CD63, CD81, Tsg101 and Alix. Real-time qPCR confirmed that these pellets contain miRNAs related to I/R injury. Our study presents a practical way to isolate EVs from intestinal tissue which is suitable for downstream applications such as miRNA analysis, and provides a novel method for investigating the mechanism of intestinal I/R injury.

Exosomes Mediate Hippocampal and Cortical Neuronal Injury Induced by Hepatic Ischemia-Reperfusion Injury through Activating Pyroptosis in Rats

Background

The neuronal injury and cognitive dysfunction after liver transplantation have severe effects on the prognosis and life quality of patients. Accumulating evidence suggests that both exosomes and pyroptosis could participate in hepatic ischemia-reperfusion injury (HIRI) and play key roles in neuronal death. However, the link between exosomes and neuronal pyroptosis in HIRI awaits further investigation.

Methods

After establishing the HIRI rat models, we primarily studied the role of pyroptosis in hippocampal and cortical neuron injury through detecting NOD-like receptor protein 3 (NLRP3), pro-caspase-1, cleaved-caspase-1, apoptosis-associated speck-like protein containing CARD (ASC), gasdermin D (GSDMD), interleukin-1beta (IL-1β), and interleukin-18 (IL-18) expressions with western blotting, immunohistochemical staining, and enzyme-linked immunosorbent assay (ELISA). Then, we intravenously injected normal male rats with exosomes isolated from the sera of HIRI-challenged rats and pretreated rats with MCC950, a specific inhibitor of NLRP3, and carried out the same assay. We also detected the levels of reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA) in the hippocampal and cortical tissues.

Results

The results indicated that NLRP3 inflammasome and caspase-1-dependent pyroptosis were activated in the hippocampus and cortex of HIRI rats. Furthermore, serum-derived exosomes from HIRI-challenged rats not only had the ability to cross the blood-brain barrier (BBB) but also had the similar effects on neuronal pyroptosis. Moreover, ROS and MDA productions were induced in the HIRI and exosome-challenged groups. In addition, to some degree, MCC950 could alleviate HIRI-mediated hippocampal and cortical neuronal pyroptosis.

Conclusion

This study experimentally demonstrated that circulating exosomes play a critical role in HIRI-mediated hippocampal and cortical injury through regulating neuronal pyroptosis.

Intestinal and Limb Ischemic Preconditioning Provides a Combined Protective Effect in the Late Phase, But not in the Early Phase, Against Intestinal Injury Induced by Intestinal Ischemia-Reperfusion in Rats

Intestinal ischemia/reperfusion (I/R) injury is associated with high morbidity and mortality. This study aimed to compare the protective efficacy of intestinal ischemic preconditioning (IIPC) and limb ischemic preconditioning (LIPC) against intestinal I/R injury and investigate their combined protective effect and the underlying mechanism. Male Sprague-Dawley rats were pretreated with IIPC, LIPC, or IIPC plus LIPC (combined), and intestinal I/R or sham operation was performed. The animals were sacrificed at 2 and 24 h after reperfusion and then blood and tissue samples were harvested for further analyses. In additional groups of animals, a 7-day survival study was conducted. The results showed that ischemic preconditioning (IPC) improved the survival rate and attenuated intestinal edema, injury, and apoptosis. IPC decreased the levels of tumor necrosis factor-α, interleukin -6, malondialdehyde and myeloperoxidase, and increased the activity of superoxide dismutase in serum and intestine after the I/R event. IPC downregulated the expression of Toll-like receptor-4 (TLR4) and nuclear factor-kappa B (NF-κB). The effect of combined pretreatment was better than that of single pretreatment in the late phase (24 h), but not in the early phase (2 h). The study demonstrated that IPC could significantly attenuate intestinal injury induced by intestinal I/R via inhibiting inflammation, oxidative stress, and apoptosis. IIPC and LIPC conferred no synergy in protecting I/R-induced intestinal injury in the early phase, but combined preconditioning had clearly stronger protection in the late phase, which was associated with the inhibition of the activated TLR4/NF-κB signaling pathway. It suggested that LIPC or combined preconditioning could potentially be applied in the clinical settings of surgical patient care.

Irisin Contributes to the Hepatoprotection of Dexmedetomidine during Intestinal Ischemia/Reperfusion

Intestinal ischemia/reperfusion (I/R), which is associated with high morbidity and mortality, is also accompanied with abnormal energy metabolism and liver injury. Irisin, a novel exercise-induced hormone, can regulate adipose browning and thermogenesis. The following study investigated the potential role of dexmedetomidine in liver injury during intestinal I/R in rats. Adult male Sprague-Dawley rats underwent occlusion of the superior mesenteric artery for 90 min followed by 2 h of reperfusion. Dexmedetomidine or irisin-neutralizing antibody was intravenously administered for 1 h before surgery. The results demonstrated that severe intestine and liver injuries occurred during intestinal I/R as evidenced by pathological scores and an apparent increase in serum diamine oxidase (DAO), aspartate aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) levels. In addition, the hepatic irisin, cleaved caspase-3, Bax, and NLRP3 inflammasome components (including NLRP3, ASC, and caspase-1), protein expressions, apoptotic index, reactive oxygen species (ROS), malondialdehyde (MDA), myeloperoxidase (MPO), tumor necrosis factor- (TNF-) α, and interleukin- (IL-) 6 levels increased; however, the serum irisin level and hepatic Bcl-2 protein expression and superoxide dismutase (SOD) activity decreased after intestinal I/R. Interestingly, dexmedetomidine could reduce the above listed changes and increase the irisin levels in plasma and the liver in I/R rats. Dexmedetomidine-mediated protective effects on liver injury and NLRP3 inflammasome activation during intestinal I/R were partially abrogated via irisin-neutralizing antibody treatment. The results suggest that irisin might contribute to the hepatoprotection of dexmedetomidine during intestinal ischemia/reperfusion.

Ginsenoside Rb1 attenuates intestinal ischemia/reperfusion‑induced inflammation and oxidative stress via activation of the PI3K/Akt/Nrf2 signaling pathway

Ginsenoside Rb1 (GRb1), one of the major active saponins isolated from ginseng, has recently been reported to protect various organs against ischemia/reperfusion (IR) injury; however, the mechanisms underlying these protective effects following intestinal IR (IIR) remain unclear. The present study aimed to evaluate the effects of GRb1 on IIR injury and determine the mechanisms involved in these effects. Sprague Dawley rats were subjected to 75 min of superior mesenteric artery occlusion, followed by 3 h of reperfusion. GRb1 (15 mg/kg) was administered intraperitoneally 1 h prior to the induction of IIR, with or without intravenous administration of Wortmannin [WM; a phosphoinositide 3-kinase (PI3K) inhibitor, 0.6 mg/kg]. The degree of intestinal injury and oxidative stress-induced damage was determined by histopathologic evaluation and measurement of the serum activity levels of D-lactate, diamine oxidase and endotoxin, and the levels of malondialdehyde (MDA), superoxide dismutase (SOD) and 8-iso-prostaglandin F_2α (8-iso-PGF_2α). The protein expression levels of p85, phosphorylated (p)-p85, protein kinase B (Akt), p-Akt and nuclear factor erythroid 2-related factor 2 (Nrf2) were determined via western blotting, and the concentrations of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β and IL-6 were measured via ELISA. It was revealed that IIR led to severe intestinal injury (as determined by significant increases in intestinal Chiu scores), which was accompanied with disruptions in the integrity of the intestinal mucosal barrier. IIR also increased the expression levels of TNF-α, IL-1β, IL-6, MDA and 8-iso-PGF_2α in the intestine, and decreased those of SOD. GRb1 reduced intestinal histological injury, and suppressed inflammatory responses and oxidative stress. Additionally, the protective effects of GRb1 were eliminated by WM. These findings indicated that GRb1 may ameliorate IIR injury by activating the PI3K/protein kinase B/Nrf2 pathway.

Targeting intestinal epithelial cell-programmed necrosis alleviates tissue injury after intestinal ischemia/reperfusion in rats

BACKGROUND

Intestinal dysfunction, especially acute pathologies linked to intestinal ischemia/reperfusion (I/R) injury, is profoundly affected by inflammation and improper execution of cell death. Few studies have examined the efficacy of combined strategies in regulated intestinal epithelial necrosis after intestinal I/R. Here, we evaluated the functional interaction between poly (adenosine diphosphate-ribose) polymerase 1 (PARP-1)-induced parthanatos and receptor-interacting protein 1/3 (RIP1/3) kinase-induced necroptosis in the pathophysiological course of acute ischemic intestinal injury.

METHODS

Anesthetized adult male Sprague-Dawley rats were subjected to superior mesenteric artery occlusion consisting of 1.5 h of ischemia and 6 h of reperfusion. The PARP-1-specific inhibitor PJ34 (10 mg/kg) and the RIP1-specific inhibitor Necrostatin-1 (1 mg/kg) were intraperitoneally administered 30 min before the induction of ischemia.

RESULTS

Intestinal I/R was found to result in PARP-1 activation and RIP1/3-mediated necrosome formation. PJ34 or Necrostatin-1 treatment significantly improved the mucosal injury, while the combined inhibition of PARP-1 and RIP1/3 conferred optimal protection of the intestine. Meanwhile, results from terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling assay showed a decrease in intestinal epithelial cell death. Interestingly, we further showed that PARP-1 might act as a downstream signaling molecule of RIP1 in the process of I/R-induced intestinal injury and that the RIP1/PARP-1-dependent cell death signaling pathway functioned independently of caspase 3 inhibition.

CONCLUSIONS

The results of our study provide a molecular basis for combination therapy that targets both pathways of regulated necrosis (parthanatos and necroptosis), to treat acute intestinal I/R-induced intestinal epithelial barrier disruption.

Outdoor Ambient Air Pollution and Neurodegenerative Diseases: the Neuroinflammation Hypothesis

PURPOSE OF REVIEW

Accumulating research indicates that ambient outdoor air pollution impacts the brain and may affect neurodegenerative diseases, yet the potential underlying mechanisms are poorly understood.

RECENT FINDINGS

The neuroinflammation hypothesis holds that elevation of cytokines and reactive oxygen species in the brain mediates the deleterious effects of urban air pollution on the central nervous system (CNS). Studies in human and animal research document that neuroinflammation occurs in response to several inhaled pollutants. Microglia are a prominent source of cytokines and reactive oxygen species in the brain, implicated in the progressive neuron damage in diverse neurodegenerative diseases, and activated by inhaled components of urban air pollution through both direct and indirect pathways. The MAC1-NOX2 pathway has been identified as a mechanism through which microglia respond to different forms of air pollution, suggesting a potential common deleterious pathway. Multiple direct and indirect pathways in response to air pollution exposure likely interact in concert to exert CNS effects.

MicroRNA-378 protects against intestinal ischemia/reperfusion injury via a mechanism involving the inhibition of intestinal mucosal cell apoptosis

Intestinal ischemia/reperfusion (I/R) injury remains a major clinical event and contributes to high morbidity and mortality rates, but the underlying mechanisms remain elusive. Recent studies have demonstrated that microRNAs (miRNAs) have important roles in organ I/R injury, but the changes and potential roles of miRNAs in intestinal I/R-induced intestinal injury are unclear. This study was designed to analyze the miRNA expression profiles in intestinal mucosa after I/R injury and to explore the role of target miRNA during this process. Using miRNA microarray analysis, we found changes of 19 miRNAs from the expression profile of miRNAs in a mouse model of intestinal I/R and further verified them by RT-qPCR. Here, we report that miR-378 is one of the markedly decreased miRNAs and found the putative target mRNA that is linked to cell death after applying the TargetScan, miRanda, CLIP-Seq and miRDB prediction algorithms. Our results show that the overexpression of miR-378 significantly ameliorated intestinal tissue damage in wild-type and transgenic mice and oxygen glucose deprivation/reperfusion-challenged IEC-6 cell injury. Moreover, miR-378 overexpression reduced intestinal epithelial cell apoptosis in both in vivo and in vitro ischemic models and attenuated cleaved caspase-3 expression. Collectively, our results revealed that the suppression of caspase-3 activation by miRNA-378 overexpression may be involved in the protective effects of intestinal ischemic damage. MiRNA-378 may serve as a key regulator and therapeutic target in intestinal I/R injury.

PKCζ phosphorylates TRAF2 to protect against intestinal ischemia-reperfusion-induced injury

Intestinal ischemia-reperfusion (I/R) is a common clinical problem that occurs during various clinical pathological processes. Excessive apoptosis has an indispensable role in intestinal I/R injury. Tumor necrosis factor receptor-associated factor 2 (TRAF2) and PKCζ have an essential role in apoptosis. Here, we aimed to investigate the effects of PKCζ and TRAF2 and to explore the correlation between PKCζ and TRAF2 in intestinal I/R injury. Mice were subjected to intestinal I/R injury in vivo. In vitro experiments were conducted by treating Caco-2 cells with hypoxia/reoxygenation (H/R) stimulation to simulate intestinal I/R. Intestinal tissue samples and Caco-2 cells were examined using various approaches. Intestinal I/R induced the membrane translocation and phosphorylation of PKCζ. Pretreatment with the PKCζ activator phosphatidylcholine remarkably attenuated gut injury by suppressing apoptosis. H/R induced PKCζ to combine with TRAF2, which was phosphorylated by PKCζ at Ser⁵⁵, but not at Ser¹¹, under intestinal I/R or H/R conditions. In addition, TRAF2 Ser⁵⁵ phosphorylation increased cell survival by inhibiting cell apoptosis in the H/R model. Mechanistically, TRAF2 Ser⁵⁵ phosphorylation promoted NF-κB activation but suppressed c-Jun activation in Caco-2 cells under H/R conditions. The results of this study demonstrate that the PKCζ/TRAF2 pathway represents a novel protective mechanism against intestinal I/R injury. Therefore, the PKCζ/TRAF2 pathway is a novel target for potential treatments of intestinal I/R injury-related diseases.

Necroptosis is a key mediator of enterocytes loss in intestinal ischaemia/reperfusion injury

Cell death is an important biological process that is believed to have a central role in intestinal ischaemia/reperfusion (I/R) injury. While the apoptosis inhibition is pivotal in preventing intestinal I/R, how necrotic cell death is regulated remains unknown. Necroptosis represents a newly discovered form of programmed cell death that combines the features of both apoptosis and necrosis, and it has been implicated in the development of a range of inflammatory diseases. Here, we show that receptor-interacting protein 1/3 (RIP1/3) kinase and mixed lineage kinase domain-like protein recruitment mediates necroptosis in a rat model of ischaemic intestinal injury in vivo. Furthermore, necroptosis was specifically blocked by the RIP1 kinase inhibitor necrostatin-1. In addition, the combined treatment of necrostatin-1 and the pan-caspase inhibitor Z-VAD acted synergistically to protect against intestinal I/R injury, and these two pathways can be converted to one another when one is inhibited. In vitro, necrostatin-1 pre-treatment reduced the necroptotic death of oxygen-glucose deprivation challenged intestinal epithelial cell-6 cells, which in turn dampened the production of pro-inflammatory cytokines (tumour necrosis factor-α and interleukin-1β), and suppressed high-mobility group box-1 (HMGB1) translocation from the nucleus to the cytoplasm and the subsequent release of HMGB1 into the supernatant, thus decreasing the activation of Toll-like receptor 4 and the receptor for advanced glycation end products. Collectively, our study reveals a robust RIP1/RIP3-dependent necroptosis pathway in intestinal I/R-induced intestinal injury in vivo and in vitro and suggests that the HMGB1 signalling is highly involved in this process, making it a novel therapeutic target for acute ischaemic intestinal injury.

Salvianolic Acids for Injection (SAFI) suppresses inflammatory responses in activated microglia to attenuate brain damage in focal cerebral ischemia

BACKGROUND

Inflammatory reactions induced by microglia in the brain play crucial roles in ischemia/reperfusion (I/R) cerebral injuries. Microglia activation has been shown to be closely related to TLR4/NF-κB signal pathways. Salvianolic acids for injection (SAFI) have been used in clinical practice to treat ischemic stroke with reported neuroprotective effects; however, the underlying mechanisms are still uncertain.

OBJECTIVE AND METHODS

First, we studied the effect of SAFI on inflammatory responses in LPS-stimulated BV-2 microglia. Then, to discover whether the beneficial in vitro effects of SAFI lead to in vivo therapeutic effects, an MCAO (Middle cerebral artery occlusion) rat model was further employed to elucidate the probable mechanism of SAFI in treating ischemic stroke. Rats in the SAFI group were given SAFI (23 or 46mg/kg) before I/R injury.

RESULTS

The results showed that SAFI treatment significantly decreased neuroinflammation and the infarction volume compared with the vehicle group. Activation of microglia cells was reduced, and TLR4/NF-κB signals, which were markedly inhibited by SAFI treatment in ischemic hemisphere, were accompanied by reduced expression and release of cytokines IL-1β and IL-6.

CONCLUSION

This study provides evidence that SAFI effectively protects the brain after cerebral ischemia, which may be caused by attenuating inflammation in microglia.

p-JAK2 plays a key role in catalpol-induced protection against rat intestinal ischemia/reperfusion injury

Catalpol attenuated rat intestinal I/R injury by decreasing mitochondria-mediated apoptosis through blocking the JAK2/STAT3 signaling pathwayviaselective inhibition of p-JAK2.

Combined Hemorrhagic Shock and Unilateral Common Carotid Occlusion Induces Neurological Injury in Adult Male Rats

Background: Clinical assessment reveals that patients after surgery of cardiopulmonary bypass or coronary bypass experience postoperative cognitive dysfunction. This study aimed to investigate whether resuscitation after a hemorrhagic shock (HS) and/or mild cerebral ischemia caused by a unilateral common carotid artery occlusion (UCCAO) can cause brain injury and concomitant neurological dysfunction, and explore the potential mechanisms. Methods: Blood withdrawal (6 mL/100 g body weight) for 60 min through the right jugular vein catheter-induced an HS. Immediately after the termination of HS, we reinfused the initially shed blood volumes to restore and maintain the mean arterial blood pressure (MABP) to the original value during the 30-min resuscitation. A cooling water blanket used to induce whole body cooling for 30 min after the end of resuscitation. Results: An UCCAO caused a slight cerebral ischemia (cerebral blood flow [CBF] 70%) without hypotension (MABP 85 mmHg), systemic inflammation, multiple organs injuries, or neurological injury. An HS caused a moderate cerebral ischemia (52% of the original CBF levels), a moderate hypotension (MABP downed to 22 mmHg), systemic inflammation, and peripheral organs injuries. However, combined an UCCAO and an HS caused a severe cerebral ischemia (18% of the original CBF levels), a moderate hypotension (MABP downed to 17 mmHg), systemic inflammation, peripheral organs damage, and neurological injury, which can be attenuated by whole body cooling. Conclusions: When combined with an HS, an UCCAO is associated with ischemic neuronal injury in the ipsilateral hemisphere of adult rat brain, which can be attenuated by therapeutic hypothermia. A resuscitation from an HS regards as a reperfusion insult which may induce neurological injury in patients with an UCCAO disease.

Characterization of 11C-GSK1482160 for Targeting the P2X7 Receptor as a Biomarker for Neuroinflammation

The purinergic receptor subtype 7 (P2X7R) represents a novel molecular target for imaging neuroinflammation via PET. GSK1482160, a potent P2X7R antagonist, has high receptor affinity, high blood-brain barrier penetration, and the ability to be radiolabeled with ¹¹C. We report the initial physical and biologic characterization of this novel ligand. Methods:¹¹C-GSK1482160 was synthesized according to published methods. Cell density studies were performed on human embryonic kidney cell lines expressing human P2X7R (HEK293-hP2X7R) and underwent Western blotting, an immunofluorescence assay, and radioimmunohistochemistry analysis using P2X7R polyclonal antibodies. Receptor density and binding potential were determined by saturation and association-disassociation kinetics, respectively. Peak immune response to lipopolysaccharide treatment in mice was determined in time course studies and analyzed via Iba1 and P2X7R Western blotting and Iba1 immunohistochemistry. Whole-animal biodistribution studies were performed on saline- or lipopolysaccharide-treated mice at 15, 30, and 60 min after radiotracer administration. Dynamic in vivo PET/CT was performed on the mice at 72 h after administration of saline, lipopolysaccharide, or lipopolysaccharide + blocking, and 2-compartment, 5-parameter tracer kinetic modeling of brain regions was performed. Results: P2X7R changed linearly with concentrations or cell numbers. For high-specific-activity ¹¹C-GSK1482160, receptor density and K_d were 1.15 ± 0.12 nM and 3.03 ± 0.10 pmol/mg, respectively, in HEK293-hP2X7R membranes. Association constant k_on, dissociation constant k_off, and binding potential (k_on/k_off) in HEK293-hP2X7R cells were 0.2312 ± 0.01542 min^-1⋅nM^-1, 0.2547 ± 0.0155 min^-1, and 1.0277 ± 0.207, respectively. Whole-brain Iba1 expression in lipopolysaccharide-treated mice peaked by 72 h on immunohistochemistry, and Western blot analysis of P2X7R for saline- and lipopolysaccharide-treated brain sections showed a respective 1.8- and 1.7-fold increase in signal enhancement at 72 h. Biodistribution of ¹¹C-GSK1482160 in saline- and lipopolysaccharide-treated mice at 72 h was statistically significant across all tissues studied. In vivo dynamic ¹¹C-GSK1482160 PET/CT of mice at 72 h after administration of saline, lipopolysaccharide, or lipopolysaccharide + blocking showed a 3.2-fold increase and 97% blocking by 30 min. The total distribution volumes for multiple cortical regions and the hippocampus showed statistically significant increases and were blocked by an excess of authentic standard GSK1482160. Conclusion: The current study provides compelling data that support the suitability of ¹¹C-GSK1482160 as a radioligand targeting P2X7R, a biomarker of neuroinflammation.