Effect of Anesthesia/Surgery on Gut Microbiota and Fecal Metabolites and Their Relationship With Cognitive Dysfunction

Short-Chain Fatty Acids Alleviate Perioperative Neurocognitive Disorders Through BDNF/PI3K/Akt Pathway in Middle-Aged Rats

Perioperative neurocognitive disorders (PND), characterized by persistent cognitive impairment lasting from days to years, present substantial clinical challenges in elderly surgical populations, profoundly compromising functional independence, quality of life, and long-term prognosis. We aimed to investigate the effects of short-chain fatty acids (SCFAs) treatment on PND via mediating Brain-derived neurotrophic factor (BDNF)/Phosphatidylinositol3-kinase (PI3K)/Protein kinase B (Akt) pathway. Using 16S rDNA sequencing targeting the V3-V4 hypervariable regions, we first demonstrated significant gut microbiota dysbiosis in PND model rats, accompanied by altered SCFAs profiles. Subsequent fecal microbiota transplantation (FMT) experiments established causal relationships between PND-associated microbial alterations and spatial cognitive deficits. Mechanistically, SCFAs supplementation attenuated neuronal damage and restored synaptic plasticity, as evidenced by Nissl staining quantification (reduced chromatolysis), TUNEL assay (decreased apoptosis rate), and immunohistochemical analysis (upregulated NeuN expression). Molecular investigations revealed that SCFAs-mediated cognitive improvement involved BDNF upregulation and subsequent PI3K/Akt pathway activation, ultimately enhancing neuronal survival and synaptic integrity. Notably, PND animals exhibited characteristic neuropathological features including synaptic density reduction (PSD-95 downregulation), neuroinflammation amplification (IL-6 elevation), and apoptosis activation-all significantly reversed by SCFA intervention. Our findings establish a novel gut-brain axis mechanism wherein microbiota-derived SCFAs may exert neuroprotection through BDNF-dependent PI3K/Akt signaling, and offer potential therapeutic strategies for PND management.

Probiotics as a possible novel therapeutic option to mitigate perioperative neurocognitive disorders: A review exploring the latest research findings

Perioperative neurocognitive disorders (PND) refer to a constellation of symptoms that primarily affect the elderly and typically manifest as common complications after exposure to surgery and anesthesia. PND is associated with high morbidity, mortality, and progression to neurodegenerative diseases, thus exerting significant financial strains on families as well as the healthcare system. Given that an ageing global population is an inevitable trend and, with the latest advances in the healthcare system, an ever-growing number of elderly people present for surgery and anesthesia, PND is of prominent concern. The two-way communication between the intestinal flora and the brain, also known as the microbiota-gut-brain axis, plays an important role in central nervous system development, and multiple studies have highlighted the influence exerted by gut microbiome in both health and disease. Pertinent studies have corroborated the fact that anesthesia and surgery disrupt the harmony of the gut ecology, which sets off a cascade of events that initiate neuroinflammation, eventually leading to PND. Probiotics, which are live microorganisms that promote the host's health, have been shown as a viable option to restore or minimise the disruption of gut flora. Evidence exists that probiotics exhibit immunomodulatory and anti-inflammatory benefits. Given the effectiveness of probiotics in reducing neuroinflammation, research has also focused on their impact on the development of PND. This review aims to compile the data from relevant clinical trials focusing on the influence of probiotics on PND to determine whether the derived findings might be applied for the prevention and treatment of PND.

Short chain fatty acids mediates complement C1q pathway alleviation of perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PND) is one of the most common postoperative complications, which can lead to a harmful impact on self-dependence, longer hospital stays, increased medical costs, morbidity, and mortality amongst older adults. Microglia can modulate synapse elimination involved in the complement component protein 1q (C1q) pathway to induce cognitive dysfunction, which is significantly improved by short chain fatty acids (SCFAs) treatment. Here we investigate the effects of SCFAs treatment on PND via mediating C1q complement pathway. High-throughput sequencing of 16S rDNA from fecal samples of male SD rats was applied to assess the changes in gut microbiota. Fecal microbiota transplantation (FMT) was performed to investigate whether gut microbiota from PND rats could alter cognitive impairment. The blood from the rat tail vein was collected to measure the SCFAs concentrations. Hippocampal and brain tissue samples were obtained to perform Western blots, Golgi and immunofluorescence staining. Primary microglia treated with SCFAs or Histone deacetylase inhibitor were cultured to measure microglial activation states and the expression of acetylated histone. The 16S rDNA sequencing results showed that PND rats had the significant changes in the species diversity of the gut microbiota and the metabolite of specifc species. Gut microbiota from PND rats could alter spatial learning and memory, and meanwhile, the changed SCFAs concentrations in plasma were involved. The synapse elimination in PND rats was strikingly reversed by SCFAs treatment involved in modulation complement C1q via suppressing neuroinflammation. This suggests that a link between gut microbiota dysbiosis and cognitive function impairment is involved in synapse elimination via mediating complement C1q pathway. SCFAs treatment can alleviate PND, the mechanisms of which may be associated with regulating complement C1q pathway.

Alterations in gut microbiota and metabolites contribute to postoperative sleep disturbances

BACKGROUND

The composition of the intestinal flora and the resulting metabolites affect patients' sleep after surgery.

METHODS

We intended to elucidate the mechanisms by which disordered intestinal flora modulate the pathophysiology of postoperative sleep disturbances in hosts. In this study, we explored the impacts of anesthesia, surgery, and postoperative sleep duration on the fecal microbiota and metabolites of individuals classified postprocedurally as poor sleepers (PS) and good sleepers (GS), as diagnosed by the bispectral index. We also performed fecal microbiota transplantation in pseudo-germ-free (PGF) rats and applied Western blotting, immunohistochemistry, and gut permeability analyses to identify the potential mechanism of its effect.

RESULTS

Research finding shows the PS group had significantly higher postoperative stool levels of the metabolites tryptophan and kynurenine than the GS group. PGF rats that received gut microbiota from PSs exhibited less rapid eye movement (REM) sleep than those that received GS microbiota (GS-PGF: 11.4% ± 1.6%, PS-PGF: 4.8% ± 2.0%, p < 0.001). Measurement of 5-hydroxytryptophan (5-HTP) levels in the stool, serum, and prefrontal cortex (PFC) indicated that altered 5-HTP levels, including reduced levels in the PFC, caused sleep loss in PGF rats transplanted with PS gut flora. Through the brain-gut axis, the inactivity of tryptophan hydroxylase 1 (TPH1) and TPH2 in the colon and PFC, respectively, caused a loss of REM sleep in PGF rats and decreased the 5-HTP level in the PFC.

CONCLUSIONS

These findings indicate that postoperative gut dysbiosis and defective 5-HTP metabolism may cause postoperative sleep disturbances. Clinicians and sleep researchers may gain new insights from this study.

Exploring the associations of gut microbiota with inflammatory and the early hematoma expansion in intracerebral hemorrhage: from change to potential therapeutic objectives

Background

Although a great deal of research has explored the possibility of a systemic inflammatory response and dysbiosis of the gut microbiota after an intracerebral hemorrhage (ICH), the relationships between gut microbiota and blood inflammatory indicators as well as their role in the hematoma expansion following an early-stage mild-to-moderate ICH (emICH) remain unknown. This study analyzes these changes and associations in order to predict and prevent hematoma expansion after emICH.

Methods

The study included 100 participants, with 70 individuals diagnosed with emICH (30 with hematoma expansion and 40 without hematoma expansion, referred to as the HE and NE groups) and 30 healthy controls matched in terms of age and gender (HC). We used 16S rRNA gene sequencing to explore the gut microbial structure and its underlying associations with blood inflammatory parameters in the HE group.

Results

Our findings showed a significant decrease in the diversity and even distribution of microorganisms in the HE group when compared to the HC and NE groups. The composition of the gut microbiota experienced notable alterations in the emICH group, especially in HE. These changes included a rise in the number of gram-negative pro-inflammatory bacteria and a decline in the level of probiotics. Furthermore, we observed strong positive connections between bacteria enriched in the HE group and levels of systemic inflammation. Several microbial biomarkers (e.g. Escherichia_Shigella, Enterobacter, and Porphyromonas) were revealed in disparateiating HE from HC and NE. Analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) exposed disturbances in essential physiological pathways, especially those related to inflammation (such as the Toll-like receptor signaling pathway), in the HE group.

Conclusions

Our exploration indicated that individuals with emICH, especially those with HE, demonstrate notably different host-microbe interactions when compared to healthy individuals. We deduced that emICH could rapidly trigger the dysbiosis of intestinal flora, and the disturbed microbiota could, in turn, exacerbate inflammatory response and increase the risk of hematoma expansion. Our comprehensive research revealed the potential of intestinal flora as a potent diagnostic tool, emphasizing its significance as a preventive target for HE.

The Role of the Intestinal Flora and Its Derivatives in Neurocognitive Disorders: A Narrative Review from Surgical Perspective

Perioperative neurocognitive dysfunction is a significant concern for population health, impacting postoperative recovery and increasing the financial burden on patients. With an increasing number of surgical procedures being performed, the prevention and management of perioperative neurocognitive dysfunction have garnered significant attention. While factors such as age, lifestyle, genetics, and education are known to influence the development of cognitive dysfunction, recent research has highlighted the role of the gut microbiota in neurological health. An increased abundance of pro-inflammatory gut microbiota can trigger and worsen neuroinflammation, neuronal cell damage, and impaired cellular autophagy. Moreover, the inflammation-promoting gut microbiota can disrupt immune function, impair neuroautophagy, and affect the production and circulation of extracellular vesicles and neurotransmitters. These factors collectively play a role in the onset and advancement of cognitive impairment. This narrative review delves into the molecular mechanisms through which gut microbiota and their derivatives contribute to cognitive impairment, focusing on the impact of anesthesia surgery, changes in gut microbial populations, and perioperative cognitive impairment associations. The study suggests that alterations in the abundance of various bacterial species and their metabolites pre- and post-surgery may be linked to postoperative cognitive impairment. Furthermore, the potential of probiotics or prebiotics in addressing cognitive impairment is discussed, offering a promising avenue for investigating the treatment of perioperative neurocognitive disorders.

Nonselective beta blockade enhances gut microbiome diversity in a rodent model of trauma, hemorrhage, and chronic stress

BACKGROUND

Traumatic injury leads to gut dysbiosis with changes in microbiome diversity and conversion toward a "pathobiome" signature characterized by a selective overabundance of pathogenic bacteria. The use of non-selective beta antagonism in trauma patients has been established as a useful adjunct to reduce systemic inflammation. We sought to investigate whether beta-adrenergic blockade following trauma would prevent the conversion of microbiome to a "pathobiome" phenotype.

METHODS

Sprague-Dawley rats (n = 6-8/group) were subjected to routine daily handling (naïve), lung contusion with hemorrhagic shock (LCHS), or LCHS with daily chronic stress (LCHS/CS), each with or without administration of intraperitoneal propranolol (BB) (10 mg/kg/day). Fecal microbiome was measured on Days 0, 7, and 14 using high-throughput 16S rRNA sequencing and QIIME2 bioinformatics analyses. Alpha- and beta-diversity and microbiome composition were assessed with significance defined as * p < 0.05.

RESULTS

Use of propranolol following LCHS or LCHS/CS demonstrated a significant increase in the number of bacterial species (Chao1 index), as well as overall richness and evenness (Shannon index) compared with their untreated counterparts at Day 7. By Day 14, these differences were no longer apparent between BB and untreated groups subjected to LCHS/CS. There was an abundance of commensal bacteria such as Oscillospiraceae and Clostridia in LCHS and LCHS/CS treated with BB after 7 days which persisted at 14 days.

CONCLUSION

These findings suggest a role for beta-antagonism in altering the diversity of the gut microbiome and the need for further studies to elucidate the cellular and molecular mechanisms underlying this intriguing connection of microbiome with trauma and beta-blockade.

Current Progress on Postoperative Cognitive Dysfunction: An Update

Postoperative cognitive dysfunction (POCD) represents a significant clinical concern, particularly among elderly surgical patients. It is characterized by a decline in cognitive performance, affecting memory, attention, coordination, orientation, verbal fluency, and executive function. This decline in cognitive abilities leads to longer hospital stays and increased mortality. This review provides a comprehensive overview of the current progress in understanding the relevant pathogenic factors, possible pathogenic mechanisms, diagnosing, prevention and treatment of POCD, as well as suggesting future research directions. It discusses neuronal damage, susceptible genes, central cholinergic system, central nervous system (CNS) inflammation, stress response and glucocorticoids, and oxidative stress in the development of POCD, aiming to uncover the pathological mechanism and develop effective treatment strategies for POCD.

Alterations in hippocampal somatostatin interneurons, GABAergic metabolism, and ASL perfusion in an aged male mouse model of POCD aggravated by sleep fragmentation

Sleep fragmentation (SF) is increasingly recognized as a contributing factor to postoperative cognitive dysfunction (POCD). Given the critical roles of somatostatin (SST) interneurons, associated gamma-aminobutyric acid (GABA)ergic neurotransmitters, and hippocampal perfusion in sleep-related cognition, this study examined changes in these mechanisms in preoperative SF affecting POCD induced by anesthesia/surgery in aged male mice. The Morris water maze (MWM), novel object recognition (NOR), and Y maze tests were utilized to evaluate POCD. Arterial spin labeling (ASL) was employed to measure hippocampal regional cerebral blood flow (rCBF). In vitro assays quantified the levels of GABAergic metabolites-such as SST, neuropeptide Y (NPY), glutamic acid decarboxylase 1 (GAD1), vesicular GABA transporter (VGAT), and GABA and the distribution of SST interneurons in the hippocampus through enzyme-linked immunosorbent assay and immunofluorescence. Preoperative 24-h SF exacerbated anesthesia/surgery-induced spatial memory impairments observed in the MWM, NOR, and Y maze tests. Preoperative 24-h SF significantly increased the number of SST interneurons in hippocampal CA1, elevated hippocampal levels of SST, NPY, GAD1, and GABA, and reduced the rCBF. Preoperative SF aggravated POCD in aged male mice, with an increased number of SST interneurons in hippocampal CA1, elevated hippocampal GABAergic metabolites, and a further reduction in rCBF.

Dysbiosis of the gut microbiota in glioblastoma patients and potential biomarkers for risk assessment

BACKGROUND

The significant death rate of glioblastoma is well-known around the world. The link between gut microbiota and glioma is becoming more studied. The goal of this study was to look at the relationships between intestinal flora and glioblastoma, and to provide a new perspective for the diagnosis as well as treatment of glioblastoma.

METHODS

Fecal samples from 80 participants with glioblastoma (n = 40) and healthy individuals (n = 40) in this study were collected as well as analyzed utilizing 16S rRNA gene amplicon sequencing in order to characterize the gut microbial community.

RESULTS

Each group has its own microbial community, and the microbial environment of glioblastoma patients had lower richness and evenness. The structure of gut microbiota community in glioblastoma patients showed profound changes, which includes the increase of pathogens in Fusobacteria and Bacteroidetes, and the reduction of probiotic bacteria in Firmicutes, Actinobacteria and Verrucomicrobia. Meanwhile, the significant correlations and clustering of OTUS (operational taxonomic units) in glioblastoma patients were discovered, and a biomarker panel (Fusobacterium, Escherichia/Shigella, Ruminococcus gnavus group, Lachnospira, Akkermansia, Parasutterella) had been used to discriminate the patients with glioblastoma from the healthy subjects (AUC: 0.80). Furthermore, the glioblastoma group exhibited multiple disturbed pathways through KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis, particularly in genetic information processing. Moreover, the prediction of phenotypic characteristics of microbiome proposed that the glioblastoma patients might have more Gram-negative bacteria and opportunistic pathogens than the healthy controls.

CONCLUSIONS

When compared to healthy people, glioblastoma sufferers have a different host-microbe interaction. Furthermore, certain types of intestinal flora could be regarded as biomarkers and drug targets for the diagnosis as well as treatment of glioblastomas.

Electroacupuncture remodels gut microbiota and metabolites in mice with perioperative neurocognitive impairment

Gut microbiota and metabolites are considered key factors in the pathogenesis of perioperative neurocognitive disorders (PND), and the brain-gut axis may be a promising target for PND treatment. Electroacupuncture has been shown to improve a wide range of neurological disorders and to restore function to the gastrointestinal tract. Thus, we hypothesized whether electroacupuncture could remodel gut microbiota and neuroinflammation induced by anesthesia/surgery. First, we observed electroacupuncture at acupoints GV20, LI4 and PC6 significantly improved memory in behavioral tests. Next, we found electroacupuncture decreased the levels of inflammatory factors (NSE, S-100β, IL-6, etc.) in the hippocampus, indicating that nerve inflammation was blocked by electroacupuncture. Furthermore, via 16S rRNA sequence analysis and LC-MS analysis, the gut microbiota and its metabolites were appropriately restored after electroacupuncture treatment. Additionally, we further confirmed the restorative effect of electroacupuncture on PND by fecal transplantation. In conclusion, the role of electroacupuncture in improving cognitive function and protecting neurons may be related to the modulation of gut microbiota and their metabolite dysregulation, thereby inhibiting neuroinflammation in PND mice.

Acute emergence of the intestinal pathobiome after postinjury pneumonia

BACKGROUND

Previous preclinical studies have demonstrated sex-specific alterations in the gut microbiome following traumatic injury or sepsis alone; however, the impact of host sex on dysbiosis in the setting of postinjury sepsis acutely is unknown. We hypothesized that multicompartmental injury with subsequent pneumonia would result in host sex-specific dysbiosis.

METHODS

Male and proestrus female Sprague-Dawley rats (n = 8/group) were subjected to either multicompartmental trauma (PT) (lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofracture), PT plus 2-hour daily restraint stress (PT/RS), PT with postinjury day 1 Pseudomonas aeruginosa pneumonia (PT-PNA), PT/RS with pneumonia (PT/RS-PNA), or naive controls. Fecal microbiome was measured on days 0 and 2 using high-throughput 16S rRNA sequencing and Quantitative Insights Into Microbial Ecology 2 bioinformatics analyses. Microbial α-diversity was assessed using Chao1 (number of different unique species) and Shannon (species richness and evenness) indices. β-diversity was assessed using principal coordinate analysis. Significance was defined as p < 0.05.

RESULTS

All groups had drastic declines in the Chao1 (α-diversity) index compared with naive controls ( p < 0.05). Groups PT-PNA and PT/RS-PNA resulted in different β-diversity arrays compared with uninfected counterparts (PT, PT/RS) ( p = 0.001). Postinjury sepsis cohorts showed a loss of commensal bacteria along with emergence of pathogenic bacteria, with blooms of Proteus in PT-PNA and Escherichia-Shigella group in PT/RS-PNA compared with other cohorts. At day 2, PT-PNA resulted in β-diversity, which was unique between males and females ( p = 0.004). Microbiome composition in PT-PNA males was dominated by Anaerostipes and Parasuterella , whereas females had increased Barnesiella and Oscillibacter . The PT/RS males had an abundance of Gastranaerophilales and Muribaculaceae .

CONCLUSION

Multicompartmental trauma complicated by sepsis significantly diminishes diversity and alters microbial composition toward a severely dysbiotic state early after injury, which varies between males and females. These findings highlight the role of sex in postinjury sepsis and the pathobiome, which may influence outcomes after severe trauma and sepsis.

Deciphering the dual role of N-methyl-D-Aspartate receptor in postoperative cognitive dysfunction: A comprehensive review

Postoperative cognitive dysfunction (POCD) is a common complication following surgery, adversely impacting patients' recovery, increasing the risk of negative outcomes, prolonged hospitalization, and higher mortality rates. The N-methyl-D-aspartate (NMDA) receptor, crucial for learning, memory, and synaptic plasticity, plays a significant role in the development of POCD. Various perioperative factors, including age and anesthetic use, can reduce NMDA receptor function, while surgical stress, inflammation, and pain may lead to its excessive activation. This review consolidates preclinical and clinical research to explore the intricate relationship between perioperative factors affecting NMDA receptor functionality and the onset of POCD. It discusses the influence of aging, anesthetic administration, perioperative injury, pain, and inflammation on the NMDA receptor-related pathophysiology of POCD. The comprehensive analysis presented aims to identify effective treatment targets for POCD, contributing to the improvement of patient outcomes post-surgery.

Murine cartilage microbial DNA deposition occurs rapidly following the introduction of a gut microbiome and changes with obesity, aging, and knee osteoarthritis

Cartilage microbial DNA patterns have been recently characterized in osteoarthritis (OA). The objectives of this study were to evaluate the gut origins of cartilage microbial DNA, to characterize cartilage microbial changes with age, obesity, and OA in mice, and correlate these to gut microbiome changes. We used 16S rRNA sequencing performed longitudinally on articular knee cartilage from germ-free (GF) mice following oral microbiome inoculation and cartilage and cecal samples from young and old wild-type mice with/without high-fat diet-induced obesity (HFD) and with/without OA induced by destabilization of the medial meniscus (DMM) to evaluate gut and cartilage microbiota. Microbial diversity was assessed, groups compared, and functional metagenomic profiles reconstructed. Findings were confirmed in an independent cohort by clade-specific qPCR. We found that cartilage microbial patterns developed at 48 h and later timepoints following oral microbiome inoculation of GF mice. Alpha diversity was increased in SPF mouse cartilage samples with age (P = 0.013), HFD (P = 5.6E-4), and OA (P = 0.029) but decreased in cecal samples with age (P = 0.014) and HFD (P = 1.5E-9). Numerous clades were altered with aging, HFD, and OA, including increases in Verrucomicrobia in both cartilage and cecal samples. Functional analysis suggested changes in dihydroorotase, glutamate-5-semialdehyde dehydrogenase, glutamate-5-kinase, and phosphoribosylamine-glycine ligase, in both cecum and cartilage, with aging, HFD, and OA. In conclusion, cartilage microbial DNA patterns develop rapidly after the introduction of a gut microbiome and change in concert with the gut microbiome during aging, HFD, and OA in mice. DMM-induced OA causes shifts in both cartilage and cecal microbiome patterns independent of other factors.

The involvement of the gut microbiota in postoperative cognitive dysfunction based on integrated metagenomic and metabolomics analysis

IMPORTANCE

As the population ages and medical technology advances, anesthesia procedures for elderly patients are becoming more common, leading to an increased prevalence of postoperative cognitive dysfunction. However, the etiology and correlation between the gut microbiota and cognitive dysfunction are poorly understood, and research in this area is limited. In this study, mice with postoperative cognitive dysfunction were found to have reduced levels of fatty acid production and anti-inflammatory flora in the gut, and Bacteroides was associated with increased depression, leading to cognitive dysfunction and depression. Furthermore, more specific microbial species were identified in the disease model, suggesting that modulation of host metabolism through gut microbes may be a potential avenue for preventing postoperative cognitive dysfunction.

Electroacupuncture modulates gut microbiota in mice: A potential target in postoperative cognitive dysfunction

The detailed mechanism of inflammation in postoperative cognitive dysfunction (POCD) is unclear. This study aimed to determine whether electroacupuncture (EA) ameliorates POCD by modulating gut microbial dysbiosis. Compared to the control group, mice in the EA group were treated at the acupoints Zusanli (ST36), Quchi (L111), Baihui (GV20), and Dazhui (GV14) 1 week before appendectomy. Novel object recognition and the Morris water maze tests were used to assess learning and spatial reference memory deficits, whereas hippocampus samples and stool samples were collected for central inflammatory tests and 16S-rRNA sequencing of intestinal flora, respectively. In amyloid precursor protein/presenilin 1 (APP/PS1) mice, EA enhanced spatial memory and learning deficits. The fecal microbial community was altered in APP/PS1 mice in the absence of EA following surgery. Among them, Coprococcus and Bacteroidetes were more abundant in the EA groups than in the control groups; however, Actinobacteriota, Helicobacteraceae, and Escherichia/shigella constitute the minor bacterial colonization in the EA groups. Furthermore, we found a significant negative correlation between Firmicutes and escape latency (Pearson correlation coefficient - 0.551, p < 0.01) and positive correlation between Proteobacteria and escape latency (Pearson correlation coefficient 0.462, p < 0.05). Electron microscopy revealed signs of blood-brain barrier (BBB) impairments and immunofluorescence images showed glial cells activated in the hippocampus of APP/PS mice without EA, and serum diamine oxidase levels were increased in these mice; whereas EA treatment significantly relieved the above pathological changes. Our findings implied that EA decreases hippocampal inflammation of APP/PS1 by upregulating benificial  gut microbiota, reducing BBB and intestinal barrier dysfunction, thus alleviates postoperative cognitive dysfunction. This may provide a novel target in POCD management.

Sex-specific intestinal dysbiosis persists after multicompartmental injury

BACKGROUND

Preclinical studies of the gut microbiome after severe traumatic injury have demonstrated severe dysbiosis in males, with sex-specific microbial differences up to 2 days after injury. However, the impact of host sex on injury-driven dysbiosis over time remains unknown. We hypothesized that sex-specific differences in intestinal microbiome diversity and composition after traumatic injury with and without stress would persist after 7 days.

METHODS

Male and proestrus female Sprague-Dawley rats (n = 8/group) were subjected to either polytrauma (lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofractures), polytrauma plus chronic restraint stress, or naïve controls. The fecal microbiome was measured on days 0, 3, and 7 using 16S rRNA sequencing and Quantitative Insights into Microbial Ecology bioinformatics analyses. Microbial alpha-diversity (Chao1 and Shannon indices) and beta-diversity were assessed. Analyses were performed in GraphPad and "R," with significance defined as P < .05.

RESULTS

Polytrauma and polytrauma plus chronic restraint stress reduced alpha-diversity (Chao1, Shannon) within 3 days postinjury, which persisted up to day 7 in both sexes; polytrauma and polytrauma plus chronic restraint stress females had significantly decreased Chao1 compared to male counterparts at day 7 (P = .02). At day 7, the microbiome composition in polytrauma females had higher proportion of Mucispirillum, whereas polytrauma plus chronic restraint stress males demonstrated elevated abundance of Ruminococcus and Akkermansia.

CONCLUSION

Multicompartmental trauma induces intestinal dysbiosis that is sex-specific with persistence of decreased diversity and unique "pathobiome" signatures in females after 1 week. These findings underline sex as an important biological variable that may influence variable host-specific responses and outcomes after severe trauma and critical illness. This underscores the need to consider precision medicine strategies to ameliorate these outcomes.

Immunonutrients and intestinal microbiota: a gap in the literature

The human intestinal microbiota is composed of a wide variety of microorganisms that play an important role in intestinal permeability, digestion, and especially, in the maturation of host's immune system. At the same time, effectiveness of immunomodulatory nutrients is known, especially in situations of stress and in strengthening body's defenses. However, the influence of the use of immunonutrients on microbiota's composition and variability is still poorly investigated. Studies indicate that the use of immunomodulators such as omega 3, glutamine, and arginine, can play a role in its modulation, through the immunological enhancement of the hosts. Therefore, this article sought to concentrate the latest evidence on the influence of the use of the main immunonutrients used in clinical practice on human gut microbiota, and their potential benefits.

Multicompartmental traumatic injury induces sex-specific alterations in the gut microbiome

BACKGROUND

Previous preclinical studies have demonstrated an altered gut microbiome after traumatic injury; however, the impact of sex on dysbiosis remains unknown. We hypothesized that the "pathobiome" phenotype induced by multicompartmental injuries and chronic stress is host sex specific with unique microbiome signatures.

METHODS

Male and proestrus female Sprague-Dawley rats (n = 8/group) aged 9 weeks to 11 weeks were subjected to either multicompartmental injury (PT) (lung contusion, hemorrhagic shock, cecectomy, bifemoral pseudofractures), PT plus 2 hours daily chronic restraint stress (PT/CS) or naive controls. Fecal microbiome was measured on Days 0 and 2 using high-throughput 16S rRNA sequencing and Quantitative Insights Into Microbial Ecology bioinformatics analyses. Microbial alpha-diversity was assessed using Chao1 (number of different unique species) and Shannon (species richness and evenness) indices. Beta-diversity was assessed using principle coordinate analysis. Intestinal permeability was evaluated by plasma occludin and lipopolysaccharide binding protein. Histologic evaluation of ileum and colon tissues was scored for injury by a blinded pathologist. Analyses were performed in GraphPad and R, with significance defined as p < 0.05 between males versus females.

RESULTS

At baseline, females had significantly elevated alpha-diversity (Chao1, Shannon indices) compared with males ( p < 0.05) which was no longer present 2 days postinjury in PT and PT/CS. Beta-diversity also differed significantly between males and females after PT ( p = 0.01). At Day 2, the microbial composition in PT/CS females was dominated by Bifidobacterium , whereas PT males demonstrated elevated levels of Roseburia ( p < 0.01). The PT/CS males had significantly elevated ileum injury scores compared with females ( p = 0.0002). Plasma occludin was higher in PT males compared with females ( p = 0.004); plasma lipopolysaccharide binding protein was elevated in PT/CS males ( p = 0.03).

CONCLUSION

Multicompartmental trauma induces significant alterations in microbiome diversity and taxa, but these signatures differ by host sex. These findings suggest that sex is an important biological variable that may influence outcomes after severe trauma and critical illness.

Alterations of gut microbiome following gastrointestinal surgical procedures and their potential complications

Intestinal microorganisms play a crucial role in shaping the host immunity and maintaining homeostasis. Nevertheless, alterations in gut bacterial composition may occur and these alterations have been linked with the pathogenesis of several diseases. In surgical practice, studies revealed that the microbiome of patients undergoing surgery changes and several post-operative complications seem to be associated with the gut microbiota composition. In this review, we aim to provide an overview of gut microbiota (GM) in surgical disease. We refer to several studies which describe alterations of GM in patients undergoing different types of surgery, we focus on the impacts of peri-operative interventions on GM and the role of GM in development of post-operative complications, such as anastomotic leak. The review aims to enhance comprehension regarding the correlation between GM and surgical procedures based in the current knowledge. However, preoperative and postoperative synthesis of GM needs to be further examined in future studies, so that GM-targeted measures could be assessed and the different surgery complications could be reduced.

The possible role of gut microbiota dysbiosis in the pathophysiology of delirium in older persons

Delirium is a clinical syndrome characterized by an acute change in attention, awareness and cognition with fluctuating course, frequently observed in older patients during hospitalization for acute medical illness or after surgery. Its pathogenesis is multifactorial and still not completely understood, but there is general consensus on the fact that it results from the interaction between an underlying predisposition, such as neurodegenerative diseases, and an acute stressor acting as a trigger, such as infection or anesthesia. Alterations in brain insulin sensitivity and metabolic function, increased blood-brain barrier permeability, neurotransmitter imbalances, abnormal microglial activation and neuroinflammation have all been involved in the pathophysiology of delirium. Interestingly, all these mechanisms can be regulated by the gut microbiota, as demonstrated in experimental studies investigating the microbiota-gut-brain axis in dementia. Aging is also associated with profound changes in gut microbiota composition and functions, which can influence several aspects of disease pathophysiology in the host. This review provides an overview of the emerging evidence linking age-related gut microbiota dysbiosis with delirium, opening new perspectives for the microbiota as a possible target of interventions aimed at delirium prevention and treatment.

Microbiome Contributions to Health

The human microbiome is vast and is present in spaces previously thought to be sterile such as the lungs. A healthy microbiome is diverse and functions in an adaptive way to support local as well as organism health and function. Furthermore, a normal microbiome is essential for normal immune system development rendering the array of microbes that live in and on the human body key components of homeostasis. A wide array of clinical conditions and interventions including anesthesia, analgesia, and surgical intervention may derange the human microbiome in a maladaptive fashion with bacterial responses spanning decreased diversity to transformation to a pathogenic phenotype. Herein, we explore the normal microbiome of the skin, gastrointestinal tract, and the lungs as prototype sites to describe the influence of the microbiomes in each of those locations on health, and how care may derange those relations.

The NLRP3 inflammasome is a potential mechanism and therapeutic target for perioperative neurocognitive disorders

Perioperative neurocognitive disorders (PNDs) are frequent complications associated with cognitive impairment during the perioperative period, including acute postoperative delirium and long-lasting postoperative cognitive dysfunction. There are some risk factors for PNDs, such as age, surgical trauma, anesthetics, and the health of the patient, but the underlying mechanism has not been fully elucidated. Pyroptosis is a form of programmed cell death that is mediated by the gasdermin protein and is involved in cognitive dysfunction disorders. The canonical pathway induced by nucleotide oligomerization domain (NOD)-, leucine-rich repeat (LRR)- and pyrin domain-containing protein 3 (NLRP3) inflammasomes contributes to PNDs, which suggests that targeting NLRP3 inflammasomes may be an effective strategy for the treatment of PNDs. Therefore, inhibiting upstream activators and blocking the assembly of the NLRP3 inflammasome may attenuate PNDs. The present review summarizes recent studies and systematically describes the pathogenesis of NLRP3 activation and regulation and potential therapeutics targeting NLRP3 inflammasomes in PNDs patients.

Multicompartmental traumatic injury and the microbiome: Shift to a pathobiome

BACKGROUND

Previous animal models have demonstrated altered gut microbiome after mild traumatic injury; however, the impact of injury severity and critical illness is unknown. We hypothesized that a rodent model of severe multicompartmental injuries and chronic stress would demonstrate microbiome alterations toward a "pathobiome" characterized by an overabundance of pathogenic organisms, which would persist 1 week after injury.

METHODS

Male Sprague-Dawley rats (n = 8 per group) were subjected to either multiple injuries (PT) (lung contusion, hemorrhagic shock, cecectomy, and bifemoral pseudofractures), PT plus daily chronic restraint stress for 2 hours (PT/CS), or naive controls. Fecal microbiome was measured on days 0, 3, and 7 using high-throughput 16S rRNA sequencing and Quantitative Insights Into Microbial Ecology 2 bioinformatics analysis. Microbial α diversity was assessed using Chao1 and Shannon indices, and β diversity with principle coordinate analysis. Intestinal permeability was evaluated by plasma occludin; ileum and descending colon tissues were reviewed for injury. Analyses were performed in GraphPad (GraphPad Software, La Jolla, CA) and R (R Foundation for Statistical Computing, Vienna, Austria), with significance defined as p < 0.05.

RESULTS

There were significant alterations in β diversity at day 3 and between all groups. By day 3, both PT and PT/CS demonstrated significantly depleted bacterial diversity (Chao1) ( p = 0.01 and p = 0.001, respectively) versus naive, which persisted up to day 7 in PT/CS only ( p = 0.001). Anaerostipes and Rothia dominated PT and Lactobacillus bloomed in PT/CS cohorts by day 7. Plasma occludin was significantly elevated in PT/CS compared with naive ( p = 0.04), and descending colon of both PT and PT/CS showed significantly higher injury compared with naive ( p = 0.005, p = 0.006).

CONCLUSIONS

Multiple injuries with and without chronic stress induces significant alterations in microbiome diversity and composition within 3 days; these changes are more prominent and persist for 1 week postinjury with stress. This rapid and persistent transition to a "pathobiome" phenotype represents a critical phenomenon that may influence outcomes after severe trauma and critical illness.

Liuwei Dihuang formula ameliorates chronic stress-induced emotional and cognitive impairments in mice by elevating hippocampal O-GlcNAc modification

A substantial body of evidence has indicated that intracerebral O-linked N-acetyl-β-D-glucosamine (O-GlcNAc), a generalized post-translational modification, was emerging as an effective regulator of stress-induced emotional and cognitive impairments. Our previous studies showed that the Liuwei Dihuang formula (LW) significantly improved the emotional and cognitive dysfunctions in various types of stress mouse models. In the current study, we sought to determine the effects of LW on intracerebral O-GlcNAc levels in chronic unpredictable mild stress (CUMS) mice. The dynamic behavioral tests showed that anxiety- and depression-like behaviors and object recognition memory of CUMS mice were improved in a dose-dependent manner after LW treatment. Moreover, linear discriminate analysis (LEfSe) of genera abundance revealed a significant difference in microbiome among the study groups. LW showed a great impact on the relative abundance of these gut microbiota in CUMS mice and reinstated them to control mouse levels. We found that LW potentially altered the Uridine diphosphate-N-acetylglucosamine (UDP-GlcNAc) biosynthesis process, and the abundance of O-GlcNAcase (OGA) and O-GlcNAc transferase (OGT) in CUMS mice, which was inferred using PICRUSt analysis. We further verified advantageous changes in hippocampal O-GlcNAc modification of CUMS mice following LW administration, as well as changes in the levels of OGA and OGT. In summary, LW intervention increased the levels of hippocampal O-GlcNAc modification and ameliorated the emotional and cognitive impairments induced by chronic stress in CUMS mice. LW therefore could be considered a potential prophylactic and therapeutic agent for chronic stress.

Decoding the contributions of gut microbiota and cerebral metabolism in acute liver injury mice with and without cognitive dysfunction

AIMS

Patients with acute liver injury (ALI) can develop cognitive dysfunction (CD). The study investigated the role of gut microbiota and cerebral metabolism in ALI mice with and without CD.

METHODS

Male C57BL/6 mice that received thioacetamide were classified into ALI mice with (susceptible) or without (unsusceptible) CD-like phenotypes by hierarchical cluster analysis of behavior. The role of gut microbiota was investigated by 16S ribosomal RNA gene sequencing and feces microbiota transplantation (FMT). ¹ H-[¹³ C] NMR and electrophysiology were used to detect the changes in cerebral neurotransmitter metabolic and synaptic transition in neurons or astrocytes.

RESULTS

Apromixlay 55% (11/20) of mice developed CD and FMT from the susceptible group transmitted CD to gut microbiota-depleted mice. Alloprevotella was enriched in the susceptible group. GABA production was decreased in the frontal cortex, while hippocampal glutamine was increased in the susceptible group. Altered Escherichia. Shigella and Alloprevotella were correlated with behaviors and cerebral metabolic kinetics and identified as good predictors of ALI-induced CD. The frequencies of both miniature inhibitory and excitatory postsynaptic currents in hippocampal CA1 and prefrontal cortex were decreased in the susceptible group.

CONCLUSION

Altered transmitter metabolism and synaptic transmission in the hippocampus and prefrontal cortex and gut microbiota disturbance may lead to ALI-induced CD.

Research progress on molecular mechanisms of general anesthetic-induced neurotoxicity and cognitive impairment in the developing brain

General anesthetics-induced neurotoxicity and cognitive impairment in developing brains have become one of the current research hotspots in the medical science community. The underlying mechanisms are complex and involve various related molecular signaling pathways, cell mediators, autophagy, and other pathological processes. However, few drugs can be directly used to treat neurotoxicity and cognitive impairment caused by general anesthetics in clinical practice. This article reviews the molecular mechanism of general anesthesia-induced neurotoxicity and cognitive impairment in the neonatal brain after surgery in the hope of providing critical references for the treatments of clinical diseases.

Postoperative Delirium in Neurosurgical Patients: Recent Insights into the Pathogenesis

Postoperative delirium (POD) is a complication characterized by disturbances in attention, awareness, and cognitive function that occur shortly after surgery or emergence from anesthesia. Since it occurs prevalently in neurosurgical patients and poses great threats to the well-being of patients, much emphasis is placed on POD in neurosurgical units. However, there are intricate theories about its pathogenesis and limited pharmacological interventions for POD. In this study, we review the recent insights into its pathogenesis, mainly based on studies within five years, and the five dominant pathological theories that account for the development of POD, with the intention of furthering our understanding and boosting its clinical management.

Effects of Early Antiretroviral Therapy on the Composition and Diversity of the Fecal Microbiome of SIV-infected Rhesus Macaques (Macaca mulatta)

HIV-infected people develop reproducible disruptions in their gastrointestinal microbiota. Despite the suppression of HIV viremia via long-term antiretroviral therapy (ART), alterations still occur in gut microbial diversity and the commensal microbiota. Mounting evidence suggests these microbial changes lead to the development of gut dysbiosis-persistent inflammation that damages the gut mucosa-and correlate with various immune defects. In this study, we examined how early ART intervention influences microbial diversity in SIV-infected rhesus macaques. Using 16S rRNA sequencing, we defined the fecal microbiome in macaques given daily ART beginning on either 3 or 7 d after SIV infection (dpi) and characterized changes in composition, α diversity, and β diversity from before infection through 112 dpi. The dominant phyla in the fecal samples before infection were Bacteroidetes, Firmicutes, Spirochaetes, and Proteobacteria. After SIV infection and ART, the relative abundance of Firmicutes and Bacteroidetes did not change significantly. Significant reductions in α diversity occurred across time when ART was initiated at 3 dpi but not at 7 dpi. Principal coordinate analysis of samples revealed a divergence in β diversity in both treatment groups after SIV infection, with significant differences depending on the timing of ART administration. These results indicate that although administration of ART at 3 or 7 dpi did not substantially alter fecal microbial composition, the timing of early ART measurably altered phylogenetic diversity.

Preoperative Intestinal Microbiome and Metabolome in Elderly Patients with Delayed Neurocognitive Recovery

BACKGROUND

Delayed neurocognitive recovery (dNCR) is a common complication of the central nervous system in elderly patients. Currently, it is not clear whether the occurrence of dNCR is associated with the intestinal microbiota and its related metabolites. This study investigated the preoperative intestinal microflora and faecal metabolites of dNCR patients.

METHODS

Twenty-two elderly urological patients were divided into a dNCR group (D group) and a non-dNCR group (ND group) according to the postoperative Mini-Mental State Examination (MMSE) score on the first and third day after surgery. A postoperative MMSE score ≤ 2 points compared with the preoperative score was considered evidence of dNCR. We used a comprehensive method that combined 16S rRNA gene sequencing and untargeted metabolomics to study the preoperative intestinal microflora and faecal metabolites of the two groups, and conducted correlation analysis between them.

RESULTS

Compared with the D group, the microbial community in the ND group was more abundant. At the family level, the ND group was significantly enriched in Lachnospiraceae, Peptostreptococcaceae and Muribaculaceae. At the genus level, the faecal microbiota of the ND group was differentially enriched in Agathobacter, Dorea, Fusicatenibacter, Coprococcus_2 and Romboutsia while that of the D group was differentially enriched in Anaerofilum. Untargeted metabolomics revealed significant differences in eight different metabolites between the two groups, including ribose, ethanol, leucine, maltose, pentadecanoic acid, malonic acid 1,3,4-dihydroxybenzoic acid and 3-hydroxypalmitic acid. In addition, differential metabolites were associated with the abundance of specific bacteria.

CONCLUSIONS

The occurrence of dNCR may be associated with the intestinal flora and its related metabolite composition of patients before surgery.

A multi-omics analysis for the prediction of neurocognitive disorders risk among the elderly in Macao

BACKGROUND

Due to the increasing ageing population, neurocognitive disorders (NCDs) have been a global public health issue, and its prevention and early diagnosis are crucial. Our previous study demonstrated that there is a significant correlation between specific populations and NCDs, but the biological characteristics of the vulnerable group predispose to NCDs are unclear. The purpose of this study is to investigate the predictors for the vulnerable group by a multi-omics analysis.

METHODS

Multi-omics approaches, including metagenomics, metabolomic and proteomic, were used to detect gut microbiota, faecal metabolites and urine exosome of 8 normal controls and 13 vulnerable elders after a rigorous screening of 400 elders in Macao. The multi-omics data were analysed using R and Bioconductor. The two-sided Wilcoxon's rank-sum test, Kruskal-Wallis rank sum test and the linear discriminant analysis effective size were applied to investigate characterized features. Moreover, a 2-year follow-up was conducted to evaluate cognitive function change of the elderly.

RESULTS

Compared with the control elders, the metagenomics of gut microbiota showed that Ruminococcus gnavus, Lachnospira eligens, Escherichia coli and Desulfovibrio piger were increased significantly in the vulnerable group. Carboxylates, like alpha-ketoglutaric acid and d-saccharic acid, and levels of vitamins had obvious differences in the faecal metabolites. There was a distinct decrease in the expression of eukaryotic translation initiation factor 2 subunit 1 (eIF2α) and amine oxidase A (MAO-A) according to the proteomic results of the urine exosomes. Moreover, the compound annual growth rate of neurocognitive scores was notably decreased in vulnerable elders.

CONCLUSIONS

The multi-omics characteristics of disturbed glyoxylate and dicarboxylate metabolism (bacteria), vitamin digestion and absorption and tricarboxylic acid cycle in vulnerable elders can serve as predictors of NCDs risk among the elderly of Macao. Intervention with them may be effective therapeutic approaches for NCDs, and the underlying mechanisms merit further exploration.

Gut Microbiome Signatures Are Predictive of Cognitive Impairment in Hypertension Patients—A Cohort Study

Growing evidence has demonstrated that hypertension was associated with dysbiosis of intestinal flora. Since intestinal microbes could critically regulate neurofunction via the intestinal–brain axis, the study aimed to reveal the role and prediction value of intestinal flora alteration in hypertension-associated cognitive impairment. A cohort of 97 participants included 63 hypertension patients and 34 healthy controls. The structure of intestinal flora was analyzed by V3–V4 16S rRNA amplicon sequencing. The cognitive function was assessed using the Montreal Cognitive Assessment (MoCA) scale, and 31 patients were considered to have cognitive impairment (MoCA &lt; 26). Patients with cognitive impairment had considerable alterations in intestinal flora structure, composition, and function compared with normal-cognitive patients. In particular, the abundance of LPS-containing taxa (Proteobacteria, Gammaproteobacteria, Enterobacterales, Enterobacteriaceae, and Escherichia–Shigella) and SCFA-producing taxon (Prevotella) significantly changed in cognition-impaired patients. Tax4Fun predication results showed downregulation of glycan biosynthesis and metabolism in hypertension patients with cognitive impairment. Additionally, the pathway was demonstrated to be significantly correlated with LPS-containing taxa (Proteobacteria, Gammaproteobacteria, Enterobacterales, Enterobacteriaceae, and Escherichia–Shigella) and SCFA-producing taxon Prevotella. Furthermore, the taxa-based multiple joint prediction model (9×) was demonstrated to have excellent diagnostic potential for cognitive impairment of hypertension patients (AUC = 0.944). The current study revealed the involvement of intestinal microbiota dysbiosis in cognition-impaired hypertension patients and provided an objective predictive index for this cognition disorder.

Neuroinflammation as the Underlying Mechanism of Postoperative Cognitive Dysfunction and Therapeutic Strategies

Postoperative cognitive dysfunction (POCD) is a common neurological complication following surgery and general anesthesia, especially in elderly patients. Severe cases delay patient discharge, affect the patient’s quality of life after surgery, and are heavy burdens to society. In addition, as the population ages, surgery is increasingly used for older patients and those with higher prevalences of complications. This trend presents a huge challenge to the current healthcare system. Although studies on POCD are ongoing, the underlying pathogenesis is still unclear due to conflicting results and lack of evidence. According to existing studies, the occurrence and development of POCD are related to multiple factors. Among them, the pathogenesis of neuroinflammation in POCD has become a focus of research in recent years, and many clinical and preclinical studies have confirmed the correlation between neuroinflammation and POCD. In this article, we reviewed how central nervous system inflammation occurred, and how it could lead to POCD with changes in peripheral circulation and the pathological pathways between peripheral circulation and the central nervous system (CNS). Furthermore, we proposed some potential therapeutic targets, diagnosis and treatment strategies at the cellular and molecular levels, and clinical applications. The goal of this article was to provide a better perspective for understanding the occurrence of POCD, its development, and preventive strategies to help manage these vulnerable geriatric patients.

General anesthesia bullies the gut: a toxic relationship with dysbiosis and cognitive dysfunction

Perioperative neurocognitive disorder (PND) is a common surgery outcome affecting up to a third of the elderly patients, and it is associated with high morbidity and increased risk for Alzheimer's disease development. PND is characterized by cognitive impairment that can manifest acutely in the form of postoperative delirium (POD) or after hospital discharge as postoperative cognitive dysfunction (POCD). Although POD and POCD are clinically distinct, their development seems to be mediated by a systemic inflammatory reaction triggered by surgical trauma that leads to dysfunction of the blood-brain barrier and facilitates the occurrence of neuroinflammation. Recent studies have suggested that the gut microbiota composition may play a pivotal role in the PND development by modulating the risk of neuroinflammation establishment. In fact, modulation of gut microbiome composition with pre- and probiotics seems to be effective for the prevention and treatment of PND in animals. Interestingly, general anesthetics seem to have major responsibility on the gut microbiota composition changes following surgery and, consequently, can be an important element in the process of PND initiation. This concept represents an important milestone for the understanding of PND pathogenesis and may unveil new opportunities for the development of preventive or mitigatory strategies against the development of these conditions. The aim of this review is to discuss how anesthetics used in general anesthesia can interact and alter the gut microbiome composition and contribute to PND development by favoring the emergence of neuroinflammation.