Mitochondrial dysfunction is associated with long-term cognitive impairment in an animal sepsis model

Abstract Background: Several different mechanisms have been proposed to explain long-term cognitive impairment in sepsis survivors. The role of persisting mitochondrial dysfunction is not known. We thus sought to determine whether stimulation of mitochondrial dynamics improves mitochondrial function and long-term cognitive impairment in an experimental model of sepsis. Methods: Sepsis was induced in adult Wistar rats by cecal ligation and perforation (CLP). Animals received intracerebroventricular injections of either rosiglitazone (biogenesis activator), rilmenidine, rapamycin (autophagy activators), or n-saline (sham control) once a day on days 7–9 after the septic insult. Cognitive impairment was assessed by inhibitory avoidance and object recognition tests. Animals were killed 24 h, 3 and 10 days after sepsis with the hippocampus and prefrontal cortex removed to determine mitochondrial function. Results: Sepsis was associated with both acute (24 h) and late (10 days) brain mitochondrial dysfunction. Markers of mitochondrial biogenesis, autophagy and mitophagy were not up-regulated during these time points. Activation of biogenesis (rosiglitazone) or autophagy (rapamycin and rilmenidine) improved brain ATP levels and ex vivo oxygen consumption and the long-term cognitive impairment observed in sepsis survivors. Conclusion: Long-term impairment of brain function is temporally related to mitochondrial dysfunction. Activators of autophagy and mitochondrial biogenesis could rescue animals from cognitive impairment.

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Interleukin-1β mediates alterations in mitochondrial fusion/fission proteins and memory impairment induced by amyloid-β oligomers

Journal of Neuroinflammation ◽

10.1186/s12974-021-02099-x ◽

2021 ◽

Vol 18 (1) ◽

Author(s):

Andre F. Batista ◽

Tayná Rody ◽

Leticia Forny-Germano ◽

Suzana Cerdeiro ◽

Maria Bellio ◽

...

Keyword(s):

Cognitive Impairment ◽

Mitochondrial Dysfunction ◽

Memory Impairment ◽

Mitochondrial Dynamics ◽

Interleukin 1 ◽

Amyloid Β ◽

Mitochondrial Fusion ◽

Synapse Loss ◽

Cynomolgus Macaques ◽

The Impact

Abstract Background The lack of effective treatments for Alzheimer’s disease (AD) reflects an incomplete understanding of disease mechanisms. Alterations in proteins involved in mitochondrial dynamics, an essential process for mitochondrial integrity and function, have been reported in AD brains. Impaired mitochondrial dynamics causes mitochondrial dysfunction and has been associated with cognitive impairment in AD. Here, we investigated a possible link between pro-inflammatory interleukin-1 (IL-1), mitochondrial dysfunction, and cognitive impairment in AD models. Methods We exposed primary hippocampal cell cultures to amyloid-β oligomers (AβOs) and carried out AβO infusions into the lateral cerebral ventricle of cynomolgus macaques to assess the impact of AβOs on proteins that regulate mitochondrial dynamics. Where indicated, primary cultures were pre-treated with mitochondrial division inhibitor 1 (mdivi-1), or with anakinra, a recombinant interleukin-1 receptor (IL-1R) antagonist used in the treatment of rheumatoid arthritis. Cognitive impairment was investigated in C57BL/6 mice that received an intracerebroventricular (i.c.v.) infusion of AβOs in the presence or absence of mdivi-1. To assess the role of interleukin-1 beta (IL-1β) in AβO-induced alterations in mitochondrial proteins and memory impairment, interleukin receptor-1 knockout (Il1r1−/−) mice received an i.c.v. infusion of AβOs. Results We report that anakinra prevented AβO-induced alteration in mitochondrial dynamics proteins in primary hippocampal cultures. Altered levels of proteins involved in mitochondrial fusion and fission were observed in the brains of cynomolgus macaques that received i.c.v. infusions of AβOs. The mitochondrial fission inhibitor, mdivi-1, alleviated synapse loss and cognitive impairment induced by AβOs in mice. In addition, AβOs failed to cause alterations in expression of mitochondrial dynamics proteins or memory impairment in Il1r1−/− mice. Conclusion These findings indicate that IL-1β mediates the impact of AβOs on proteins involved in mitochondrial dynamics and that strategies aimed to prevent pathological alterations in those proteins may counteract synapse loss and cognitive impairment in AD.

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DNA Methylation of PGC-1α Is Associated With Elevated mtDNA Copy Number and Altered Urinary Metabolites in Autism Spectrum Disorder

Frontiers in Cell and Developmental Biology ◽

10.3389/fcell.2021.696428 ◽

2021 ◽

Vol 9 ◽

Author(s):

Sophia Bam ◽

Erin Buchanan ◽

Caitlyn Mahony ◽

Colleen O’Ryan

Keyword(s):

Autism Spectrum Disorder ◽

Dna Methylation ◽

Mitochondrial Dysfunction ◽

Mitochondrial Biogenesis ◽

Mitochondrial Function ◽

Copy Number ◽

Autism Spectrum ◽

Differential Methylation ◽

Mtdna Copy Number ◽

Key Genes

Autism spectrum disorder (ASD) is a complex disorder that is underpinned by numerous dysregulated biological pathways, including pathways that affect mitochondrial function. Epigenetic mechanisms contribute to this dysregulation and DNA methylation is an important factor in the etiology of ASD. We measured DNA methylation of peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α), as well as five genes involved in regulating mitochondrial homeostasis to examine mitochondrial dysfunction in an ASD cohort of South African children. Using targeted Next Generation bisulfite sequencing, we found differential methylation (p < 0.05) at six key genes converging on mitochondrial biogenesis, fission and fusion in ASD, namely PGC-1α, STOML2, MFN2, FIS1, OPA1, and GABPA. PGC-1α, the transcriptional regulator of biogenesis, was significantly hypermethylated at eight CpG sites in the gene promoter, one of which contained a putative binding site for CAMP response binding element 1 (CREB1) (p = 1 × 10–6). Mitochondrial DNA (mtDNA) copy number, a marker of mitochondrial function, was elevated (p = 0.002) in ASD compared to controls and correlated significantly with DNA methylation at the PGC-1α promoter and there was a positive correlation between methylation at PGC-1α CpG#1 and mtDNA copy number (Spearman’s r = 0.2, n = 49, p = 0.04) in ASD. Furthermore, DNA methylation at PGC-1α CpG#1 and mtDNA copy number correlated significantly (p < 0.05) with levels of urinary organic acids associated with mitochondrial dysfunction, oxidative stress, and neuroendocrinology. Our data show differential methylation in ASD at six key genes converging on PGC-1α-dependent regulation of mitochondrial biogenesis and function. We demonstrate that methylation at the PGC-1α promoter is associated with elevated mtDNA copy number and metabolomic evidence of mitochondrial dysfunction in ASD. This highlights an unexplored role for DNA methylation in regulating specific pathways involved in mitochondrial biogenesis, fission and fusion contributing to mitochondrial dysfunction in ASD.

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Neural stem cells traffic functional mitochondria via extracellular vesicles to correct mitochondrial dysfunction in target cells

10.1101/2020.01.29.923441 ◽

2020 ◽

Author(s):

Luca Peruzzotti-Jametti ◽

Joshua D. Bernstock ◽

Giulia Manferrari ◽

Rebecca Rogall ◽

Erika Fernandez-Vizarra ◽

...

Keyword(s):

Multiple Sclerosis ◽

Stem Cell ◽

Mitochondrial Dysfunction ◽

Extracellular Vesicles ◽

Mitochondrial Function ◽

Mitochondrial Dynamics ◽

Mononuclear Phagocytes ◽

Host Cells ◽

Target Cells ◽

Therapeutic Effects

AbstractNeural stem cell (NSC) transplantation induces recovery in animal models of central nervous system (CNS) diseases. Although the replacement of lost endogenous cells was originally proposed as the primary healing mechanism of NSC grafts, it is now clear that transplanted NSCs operate via multiple mechanisms, including the horizontal exchange of therapeutic cargoes to host cells via extracellular vesicles (EVs).EVs are membrane particles trafficking nucleic acids, proteins, metabolites and metabolic enzymes, lipids and entire organelles. However, the function and the contribution of these cargoes to the broad therapeutic effects of NSCs is yet to be fully understood. Mitochondrial dysfunction is an established feature of several inflammatory and degenerative CNS disorders, most of which are potentially treatable with exogenous stem cell therapeutics.Herein we investigated the hypothesis that NSCs release and traffic functional mitochondria via EVs to restore mitochondrial function in target cells.Untargeted proteomics revealed a significant enrichment of mitochondrial proteins spontaneously released by NSCs in EVs. Morphological and functional analyses confirmed the presence of ultrastructurally intact mitochondria within EVs (Mito-EVs) with conserved membrane potential and respiration. We found that the transfer of Mito-EVs to mtDNA-deficient L929 Rho0 cells rescued mitochondrial function and increased Rho0 cell survival. Furthermore, the incorporation of Mito-EVs into inflammatory professional phagocytes restored normal mitochondrial dynamics and cellular metabolism and reduced the expression of pro-inflammatory markers in target cells. When transplanted in an animal model of multiple sclerosis, exogenous NSCs actively transferred mitochondria to mononuclear phagocytes and induced a significant amelioration of clinical deficits.Our data provide the first evidence that NSCs deliver functional mitochondria to target cells via Mito-EVs, paving the way for the development of novel (a)cellular approaches aimed at restoring mitochondrial dysfunction not only in multiple sclerosis, but also in degenerative neurological diseases.

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Abstract P608: Obesity Induced Hypertension Exacerbated Through Upregulation Of Renal Naci Cotransporter, Reversed By Increasing Pgc-1α-ho-1 Gene Expression To Restore Mitochondrial Function

Hypertension ◽

10.1161/hyp.68.suppl_1.p608 ◽

2016 ◽

Vol 68 (suppl_1) ◽

Author(s):

David Bamshad ◽

Jian Cao ◽

Joseph Schragenheim ◽

Charles T Stier ◽

Nader G Abraham

Keyword(s):

Mitochondrial Dysfunction ◽

Mitochondrial Biogenesis ◽

Mitochondrial Function ◽

Sodium Excretion ◽

Leptin Receptor ◽

Insulin Receptors ◽

Urinary Sodium Excretion ◽

Induced Hypertension ◽

Group A ◽

Group B

Introduction: Hypertension caused by chronic obesity as a result of high calorie food intake or in leptin receptor deficient db/db mice may be linked to mitochondrial dysfunction. Previously we and others have shown that an epoxyeicosatrienoic acid agonist (EET-A), reduced adiposity and ROS resulting in normalization of BP by unknown mechanisms. We hypothesize that EET-A will attenuate BP by restoring mitochondrial function through increasing the PGC-1α-HO-1 axis and increasing urinary sodium excretion by downregulating NCC channels. Methods: Db/db mice at 16-wks of age were divided into 3 treatment groups and for an additional 16-wks received: A) control, B) EET-A 1.5mg/100g BW i.p. 2x/week and C) EET-A and lentiviral (Ln)- PGC-1α shRNA (to suppress PGC-1α protein). Oxygen consumption (VO 2 ), visceral fat and blood glucose were determined. Additionally, renal tissues were harvested to measure the type 2 Na-K-Cl cotransporters (NKCC2), epithelial Na channels- (ENaC), NaCl cotransporters (NCC), PGC-1α, HO-1, insulin receptors, and mitochondrial biogenesis markers. Results: At the conclusion of 32 weeks: Group A, developed hypertension and presented with decreased urinary Na excretion, decreased VO 2 , decreased downstream PGC-1α signaling, and mitochondrial dysfunction. There were increased levels of NCCs but not of NKCC2s or ENaCs. Renal PGC-1α, HO-1, pAMPK, and mitochondrial fusion protein Mfn 1/2, and Opa1 were decreased, p<0.05. Group B, exhibited restoration of renal levels of PGC-1α, HO-1, pAMPK, and mitochondrial biogenesis proteins Mfn 1/2 and Opa1. NCC expression was reduced and was associated with an increase in urinary Na excretion; (p<0.05). The beneficial effect of EET-A observed in group B was suppressed in group C using Ln- PGC-1α shRNA which suppressed PGC-1α expression in renal tissue > 50% and was accompanied by the onset of even more severe suppression of urinary Na excretion than in Group A. Conclusion: Treatment of obese mice with EET-agonists leads to the recruitment of PGC-1α-HO-1 which enhances mitochondrial function and induces the downregulation of NCC channels and increased sodium excretion. EET may serve as a powerful therapeutic agent for the treatment of obesity induced hypertension.

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Mitochondrial Quality Control Mechanisms and the PHB (Prohibitin) Complex

Cells ◽

10.3390/cells7120238 ◽

2018 ◽

Vol 7 (12) ◽

pp. 238 ◽

Cited By ~ 16

Author(s):

Blanca Hernando-Rodríguez ◽

Marta Artal-Sanz

Keyword(s):

Quality Control ◽

Mitochondrial Biogenesis ◽

Mitochondrial Function ◽

Stress Responses ◽

Membrane Lipids ◽

Mitochondrial Dynamics ◽

Mitochondrial Gene ◽

Control Mechanisms ◽

Mitochondrial Homeostasis ◽

Mitochondrial Functions

Mitochondrial functions are essential for life, critical for development, maintenance of stem cells, adaptation to physiological changes, responses to stress, and aging. The complexity of mitochondrial biogenesis requires coordinated nuclear and mitochondrial gene expression, owing to the need of stoichiometrically assemble the oxidative phosphorylation (OXPHOS) system for ATP production. It requires, in addition, the import of a large number of proteins from the cytosol to keep optimal mitochondrial function and metabolism. Moreover, mitochondria require lipid supply for membrane biogenesis, while it is itself essential for the synthesis of membrane lipids. To achieve mitochondrial homeostasis, multiple mechanisms of quality control have evolved to ensure that mitochondrial function meets cell, tissue, and organismal demands. Herein, we give an overview of mitochondrial mechanisms that are activated in response to stress, including mitochondrial dynamics, mitophagy and the mitochondrial unfolded protein response (UPRmt). We then discuss the role of these stress responses in aging, with particular focus on Caenorhabditis elegans. Finally, we review observations that point to the mitochondrial prohibitin (PHB) complex as a key player in mitochondrial homeostasis, being essential for mitochondrial biogenesis and degradation, and responding to mitochondrial stress. Understanding how mitochondria responds to stress and how such responses are regulated is pivotal to combat aging and disease.

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Targeting the Blood-Brain Barrier to Prevent Sepsis-Associated Cognitive Impairment

Journal of Central Nervous System Disease ◽

10.1177/1179573519840652 ◽

2019 ◽

Vol 11 ◽

pp. 117957351984065 ◽

Cited By ~ 23

Author(s):

Divine C Nwafor ◽

Allison L Brichacek ◽

Afroz S Mohammad ◽

Jessica Griffith ◽

Brandon P Lucke-Wold ◽

...

Keyword(s):

Cognitive Impairment ◽

Blood Brain Barrier ◽

Immune Cell ◽

The United States ◽

Brain Barrier ◽

Blood Brain ◽

Systemic Inflammatory Disease ◽

Sepsis Survivors ◽

The Brain

Sepsis is a systemic inflammatory disease resulting from an infection. This disorder affects 750 000 people annually in the United States and has a 62% rehospitalization rate. Septic symptoms range from typical flu-like symptoms (eg, headache, fever) to a multifactorial syndrome known as sepsis-associated encephalopathy (SAE). Patients with SAE exhibit an acute altered mental status and often have higher mortality and morbidity. In addition, many sepsis survivors are also burdened with long-term cognitive impairment. The mechanisms through which sepsis initiates SAE and promotes long-term cognitive impairment in septic survivors are poorly understood. Due to its unique role as an interface between the brain and the periphery, numerous studies support a regulatory role for the blood-brain barrier (BBB) in the progression of acute and chronic brain dysfunction. In this review, we discuss the current body of literature which supports the BBB as a nexus which integrates signals from the brain and the periphery in sepsis. We highlight key insights on the mechanisms that contribute to the BBB’s role in sepsis which include neuroinflammation, increased barrier permeability, immune cell infiltration, mitochondrial dysfunction, and a potential barrier role for tissue non-specific alkaline phosphatase (TNAP). Finally, we address current drug treatments (eg, antimicrobials and intravenous immunoglobulins) for sepsis and their potential outcomes on brain function. A comprehensive understanding of these mechanisms may enable clinicians to target specific aspects of BBB function as a therapeutic tool to limit long-term cognitive impairment in sepsis survivors.

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Protective effects of a natural product, curcumin, against amyloid β induced mitochondrial and synaptic toxicities in Alzheimer's disease

Journal of Investigative Medicine ◽

10.1136/jim-2016-000240 ◽

2016 ◽

Vol 64 (8) ◽

pp. 1220-1234 ◽

Cited By ~ 57

Author(s):

P Hemachandra Reddy ◽

Maria Manczak ◽

Xiangling Yin ◽

Mary Catharine Grady ◽

Andrew Mitchell ◽

...

Keyword(s):

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Cell Viability ◽

Natural Product ◽

Mitochondrial Biogenesis ◽

Mitochondrial Function ◽

Mitochondrial Dynamics ◽

Amyloid Β ◽

Synaptic Activity ◽

Protective Effects

The purpose of our study was to investigate the protective effects of a natural product—‘curcumin’— in Alzheimer's disease (AD)-like neurons. Although much research has been done in AD, very little has been reported on the effects of curcumin on mitochondrial biogenesis, dynamics, function and synaptic activities. Therefore, the present study investigated the protective effects against amyloid β (Aβ) induced mitochondrial and synaptic toxicities. Using human neuroblastoma (SHSY5Y) cells, curcumin and Aβ, we studied the protective effects of curcumin against Aβ. Further, we also studied preventive (curcumin+Aβ) and intervention (Aβ+curcumin) effects of curcumin against Aβ in SHSY5Y cells. Using real time RT-PCR, immunoblotting and immunofluorescence analysis, we measured mRNA and protein levels of mitochondrial dynamics, mitochondrial biogenesis and synaptic genes. We also assessed mitochondrial function by measuring hydrogen peroxide, lipid peroxidation, cytochrome oxidase activity and mitochondrial ATP. Cell viability was studied using the MTT assay. Aβ was found to impair mitochondrial dynamics, reduce mitochondrial biogenesis and decrease synaptic activity and mitochondrial function. In contrast, curcumin enhanced mitochondrial fusion activity and reduced fission machinery, and increased biogenesis and synaptic proteins. Mitochondrial function and cell viability were elevated in curcumin treated cells. Interestingly, curcumin pre- and post-treated cells incubated with Aβ showed reduced mitochondrial dysfunction, and maintained cell viability and mitochondrial dynamics, mitochondrial biogenesis and synaptic activity. Further, the protective effects of curcumin were stronger in pretreated SHSY5Y cells than in post-treated cells, indicating that curcumin works better in prevention than treatment in AD-like neurons. Our findings suggest that curcumin is a promising drug molecule to treat AD patients.

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Estrogen Deficiency Induces Mitochondrial Damage Prior to Emergence of Cognitive Deficits in a Postmenopausal Mouse Model

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.713819 ◽

2021 ◽

Vol 13 ◽

Author(s):

Wei Zhao ◽

Yue Hou ◽

Xinxin Song ◽

Lei Wang ◽

Fangfang Zhang ◽

...

Keyword(s):

Mouse Model ◽

Mitochondrial Biogenesis ◽

Cognitive Deficits ◽

Mitochondrial Function ◽

Mitochondrial Dynamics ◽

Immunofluorescence Assay ◽

Estrogen Deficiency ◽

Mitochondrial Damage ◽

Menopausal Women ◽

The Impact

Background: Estrogen deficiency contributes to the development of Alzheimer’s disease (AD) in menopausal women. In the current study, we examined the impact of estrogen deficiency on mitochondrial function and cognition using a postmenopausal mouse model.Methods: Bilateral ovariectomy was conducted in adult females C57BL/6J. Cognitive function was examined using the Morris water maze (MWM) test at 2 weeks, 1, 2, and 3 months after ovariectomy. Neurodegeneration was assessed using an immunofluorescence assay of microtubule-associated protein 2 (MAP2) in the hippocampus and immunoblotting against postsynaptic density-95 (PSD95). Mitochondrial function in the hippocampus was assessed using immunoblotting for NDUFB8, SDHB, UQCRC2, MTCO1, and ATP5A1. Mitochondrial biogenesis was examined using immunoblotting for PGC-1α, NRF1, and mtTFA. Mitochondrion fission was assessed with immunoblotting for Drp1, whereas mitochondrion fusion was analyzed with immunoblotting for OPA1 and Mfn2. Mitophagy was examined with immunoblotting for PINK1 and LC3B. Mice receiving sham surgery were used as controls.Results: Ovariectomy resulted in significant learning and memory deficits in the MWM test at 3 months, but not at any earlier time points. At 2 weeks after ovariectomy, levels of Drp1 phosphorylated at Ser637 decreased in the hippocampus. At 1 month after ovariectomy, hippocampal levels of NDUFB8, SDHB, PGC-1α, mtTFA, OPA1, and Mfn2 were significantly reduced. At 2 months after ovariectomy, hippocampal levels of MAP2, PSD95, MTCO1, NRF1, and Pink1 were also reduced. At 3 months, levels of LC3B-II were reduced.Conclusions: The cognitive decline associated with estrogen deficiency is preceded by mitochondrial dysfunction, abnormal mitochondrial biogenesis, irregular mitochondrial dynamics, and decreased mitophagy. Thus, mitochondrial damage may contribute to cognitive impairment associated with estrogen deficiency.

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Mitochondrial Dysfunction and Oxidative Stress in Alzheimer’s Disease

Frontiers in Aging Neuroscience ◽

10.3389/fnagi.2021.617588 ◽

2021 ◽

Vol 13 ◽

Cited By ~ 1

Author(s):

Afzal Misrani ◽

Sidra Tabassum ◽

Li Yang

Keyword(s):

Oxidative Stress ◽

Alzheimer’S Disease ◽

Alzheimer's Disease ◽

Mitochondrial Dysfunction ◽

Mitochondrial Function ◽

Mitochondrial Dynamics ◽

Mitochondrial Morphology ◽

Therapeutic Approaches ◽

The Impact ◽

And Oxidative Stress

Mitochondria play a pivotal role in bioenergetics and respiratory functions, which are essential for the numerous biochemical processes underpinning cell viability. Mitochondrial morphology changes rapidly in response to external insults and changes in metabolic status via fission and fusion processes (so-called mitochondrial dynamics) that maintain mitochondrial quality and homeostasis. Damaged mitochondria are removed by a process known as mitophagy, which involves their degradation by a specific autophagosomal pathway. Over the last few years, remarkable efforts have been made to investigate the impact on the pathogenesis of Alzheimer’s disease (AD) of various forms of mitochondrial dysfunction, such as excessive reactive oxygen species (ROS) production, mitochondrial Ca2+ dyshomeostasis, loss of ATP, and defects in mitochondrial dynamics and transport, and mitophagy. Recent research suggests that restoration of mitochondrial function by physical exercise, an antioxidant diet, or therapeutic approaches can delay the onset and slow the progression of AD. In this review, we focus on recent progress that highlights the crucial role of alterations in mitochondrial function and oxidative stress in the pathogenesis of AD, emphasizing a framework of existing and potential therapeutic approaches.

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INT-777 Improves Cognitive Impairment after Sepsis by Attenuating Neuroinflammation Through the TGR5/cAMP/PKA/CREB Signaling Axis in Rats

10.21203/rs.3.rs-36666/v1 ◽

2020 ◽

Author(s):

Peng Jin ◽

Shuixiang Deng ◽

Mi Tian ◽

Pengju Wei ◽

Yao Wang ◽

...

Keyword(s):

Cognitive Impairment ◽

Survival Rate ◽

Cell Activation ◽

Cecal Ligation ◽

Clinical Score ◽

Inflammatory Factors ◽

Experimental Sepsis ◽

Sprague Dawley ◽

Neuroprotective Effects ◽

Sepsis Survivors

Abstract Background: Sepsis survivors are left with significant cognitive and behavioral impairments after discharge, but research on the relevant mechanisms and interventions remains lacking. TGR5 plays a neuroprotective role in many neurologic disease models through different mechanisms. To date, no studies have assessed the effects of TGR5 on neuroinflammation or cognitive or behavioral changes in sepsis models.Methods: A total of 267 eight-week-old male Sprague-Dawley rats were used in this study. Sepsis was induced by cecal ligation and puncture (CLP). All animals received volume resuscitation. The rats were given TGR5 CRISPR oligonucleotide intracerebroventricularly 48 hours before CLP surgery. INT-777 was administered intranasally 1 hour after CLP, and the cAMP inhibitor SQ22536 was administered intracerebroventricularly 1 hour after CLP. Survival rate, bodyweight change, clinical score, neurobehavioral tests, western blot, and immunofluorescence staining were performed. The cognitive function of rats was measured by Morris water maze during 15-20 days after CLP.Results: The expression of TGR5 in the rat hippocampus was upregulated and peaked at 3 days after CLP. The survival rate of rats after CLP was less than 50%, and the growth rate in terms of weight was significantly decreased, while these changes were not improved by INT-777 treatment. However, INT-777 treatment reduced the clinical scores of rats at 24 hours after CLP. On day 15 and later, the surviving mice completed a series of behavioral tests. CLP rats showed spatial and memory deficits and anxiety-like behaviors, and INT-777 treatment significantly improved these effects. Mechanistically, immunofluorescence analysis showed that INT-777 treatment reduced the number of microglia in the hippocampus, neutrophil infiltration and the expression of inflammatory factors after CLP in rats. Moreover, INT-777 treatment significantly increased the expression of TGR5, cAMP, p-PKA, and p-CREB and downregulated the expression of IL-1β, IL-6 and TNF-α. CRISPR-mediated TGR5 knockdown and SQ22536 treatment abolished the neuroprotective effects of TGR5 activation after CLP.Conclusion: This study demonstrates that INT-777 treatment reduced neuroinflammation and microglial cell activation, and then improved cognitive impairment in the experimental sepsis rats. TGR5 has translational potential as a therapeutic target to improve neurological outcomes in sepsis survivors.

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