Preoperative Status of Gut Microbiota Predicts Postoperative Delirium in Patients With Gastric Cancer

Sodium Butyrate Ameliorates Postoperative Delirium by Regulating Gut Microbiota Dysbiosis to Inhibit Astrocyte Activation in Aged Mice

Postoperative delirium (POD) is a common complication in elderly surgical patients, with limited targeted interventions due to incomplete understanding of its pathophysiological mechanisms. Central nervous system (CNS) inflammation, involving glial cell activation, particularly astrocytes, is considered crucial in POD development. Butyrate, a four-carbon fatty acid, has shown protective effects in CNS diseases, but its potential in mitigating POD remains unclear. This study aimed to investigate the impact of sodium butyrate on POD in aged mice. Behavioral tests, including open field, Y maze, and food burying tests, demonstrated that sodium butyrate preconditioning ameliorated laparotomy-induced delirium in aged mice. Pre-treatment with sodium butyrate inhibited astrocyte activation in the hippocampus, reduced interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) expression levels, and protected hippocampal neurons. Furthermore, the study revealed a connection between gut microbiota regulation and central neuroprotective effects mediated by astrocyte activation inhibition. Sodium butyrate improved the intestinal morphological barrier by rebalancing gut microbiota, inhibiting Proteobacteria and Actinobacteria, reducing Allobaculum and Bacteroides abundance, and increasing Oscillospira abundance. This regulation decreased gut permeability, limiting the entry of toxic substances into the bloodstream, thereby reducing inflammation spread and astrocyte overactivation, leading to central anti-inflammatory effects. In conclusion, sodium butyrate may ameliorate POD by inhibiting astrocyte-mediated neuroinflammation through gut microbiota rebalancing.

Preoperative gut microbiota of POCD patients induces pre- and postoperative cognitive impairment and systemic inflammation in rats

BACKGROUND

Postoperative cognitive dysfunction (POCD) is common following surgery in elderly patients. The role of the preoperative gut microbiota in POCD has attracted increasing attention, but the potential underlying mechanisms remain unclear. This research aimed to investigate the impact of the preoperative gut microbiota on POCD.

METHODS

Herein, we analyzed the preoperative gut microbiota of POCD patients through a prospective specimen collection and retrospective blinded evaluation study. Then, we transferred the preoperative gut microbiota of POCD patients to antibiotic-treated rats and established POCD model by abdominal surgery to explore the impact of the preoperative gut microbiota on pre- and postoperative cognitive function and systemic inflammation. The gut microbiota was analyzed using 16S rRNA sequencing analysis. The Morris water maze test was performed to evaluate learning and memory abilities. The inflammatory cytokines TNF-α, IL-1β and IL-6 in the serum and hippocampus were measured by ELISA. Microglia were examined by immunofluorescence staining for Iba-1.

RESULTS

Based on the decrease in the postoperative MMSE score, 24 patients were identified as having POCD and were matched with 24 control patients. Compared with control patients, POCD patients exhibited higher BMI and lower preoperative MMSE score. The preoperative gut microbiota of POCD patients had lower bacterial richness but a larger distribution, decreased abundance of Firmicutes and increased abundance of Proteobacteria than did that of control patients. Compared with rats that received preoperative fecal samples of control patients, rats that received preoperative fecal samples of POCD patients presented an increased abundance of Desulfobacterota, decreased cognitive function, increased levels of TNF-α and IL-1β in the serum, increased levels of TNF-α and greater microglial activation in the hippocampus. Additionally, correlation analysis revealed a positive association between the abundance of Desulfobacterota and the level of serum TNF-α in rats. Then, we performed abdominal surgery to investigate the impact of the preoperative gut microbiota on postoperative conditions, and the surgery did indeed cause POCD and inflammatory response. Notably, compared with rats that received preoperative fecal samples of control patients, rats that received preoperative fecal samples of POCD patients displayed exacerbated cognitive impairment; increased levels of TNF-α, IL-1β and IL-6 in the serum and hippocampus; and increased activation of microglia in the hippocampus.

CONCLUSIONS

Our findings suggest that the preoperative gut microbiota of POCD patients can induce preoperative and aggravate postoperative cognitive impairment and systemic inflammation in rats. Modulating inflammation by targeting the gut microbiota might be a promising approach for preventing POCD.

The role of gut microbiota in chronic restraint stress-induced cognitive deficits in mice

BACKGROUND

Chronic stress induces cognitive deficits. There is a well-established connection between the enteric and central nervous systems through the microbiota-gut-brain (MGB) axis. However, the effects of the gut microbiota on cognitive deficits remain unclear. The present study aimed to elucidate the microbiota composition in cognitive deficits and explore its potential in predicting chronic stress-induced cognitive deficits.

METHODS

Mice were randomly divided into control and chronic restraint stress (CRS) groups. The mice subjected to CRS were further divided into cognitive deficit (CRS-CD) and non-cognitive deficit (CRS-NCD) groups using hierarchical cluster analysis of novel object recognition test results. The composition and diversity of the gut microbiota were analyzed.

RESULTS

After being subjected to chronic restraint distress, the CRS-CD mice travelled shorter movement distances (p = 0.034 vs. CRS-NCD; p < 0.001 vs. control) and had a lower recognition index than the CRS-NCD (p < 0.0001 vs. CRS-NCD; p < 0.0001 vs. control) and control mice. The results revealed that 5 gut bacteria at genus levels were significantly different in the fecal samples of mice in the three groups. Further analyses demonstrated that Muricomes were not only significantly enriched in the CRS-CD group but also correlated with a decreased cognitive index. The area under the receiver operating curve of Muricomes for CRS-induced cognitive deficits was 0.96.

CONCLUSIONS

Our study indicates that the composition of the gut microbiota is involved in the development of cognitive deficits induced by chronic restraint stress. Further analysis revealed that Muricomes have the potential to predict the development of chronic stress-induced cognitive deficits in mice.

Postoperative Delirium and Neurocognitive Disorders: Updates for Providers Caring for Cancer Patients

PURPOSE OF REVIEW

To provide up to date information on postoperative delirium and neurocognitive disorders in surgical cancer patients.

RECENT FINDINGS

Established risk factors such as age, psychosocial factors, comorbidities, frailty and preexisting cognitive decline continue to exhibit associations with perioperative neurocognitive disorders (PND); novel risk factors identified recently include microbiome composition and vitamin D deficiency. Prevention measures include cognitive prehabilitation, perioperative geriatric assessment and multidisciplinary care, dexmedetomidine and multimodal analgesic techniques. Studies investigating ciprofol, remimazolam, esketamine, ramelteon and suvorexant have shown encouraging results. Controversy remains regarding the use of inhalational versus intravenous general anesthesia. Innovative approaches to address PND are a rapidly developing area of research, but more studies are needed to identify effective prevention and management interventions. Despite challenges and controversy in the field, implementation of best practice can reduce the detrimental impact of PND on patients, caregivers, and society at large.

Exploring Causal Links Between Gut Microbiota and Geriatric Syndromes: A Two-Sample Mendelian Randomization Analysis

Background: Both observational studies and clinical trials have demonstrated a link between the gut microbiota and the geriatric syndrome. Nevertheless, the exact nature of this relationship, particularly concerning causality, remains elusive. Mendelian randomization (MR) is a method of inference based on genetic variation to assess the causal relationship between an exposure and an outcome. In this study, we conducted a two-sample Mendelian randomization (TSMR) study to fully reveal the potential genetic causal effects of gut microbiota on geriatric syndromes. Methods: This study used data from genome wide association studies (GWAS) to investigate causal relationships between the gut microbiota and geriatric syndromes, including frailty, Parkinson's disease (PD), delirium, insomnia, and depression. The primary causal relationships were evaluated using the inverse-variance weighted method, MR Egger, simple mode, weighted mode and weighted median. To assess the robustness of the results, horizontal pleiotropy was examined through MR-Egger intercept and MR-presso methods. Heterogeneity was assessed using Cochran's Q test, and sensitivity was evaluated via the leave-one-out method. Results: We identified 41 probable causal relationships between gut microbiota and five geriatric syndrome-associated illnesses using the inverse-variance weighted method. Frailty showed five positive and two negative causal relationships, while PD revealed three positive and four negative causal connections. Delirium showed three positive and two negative causal relationships. Similarly, insomnia demonstrated nine positive and two negative causal connections, while depression presented nine positive and two negative causal relationships. Conclusions: Using the TSMR method and data from the public GWAS database and, we observed associations between specific microbiota groups and geriatric syndromes. These findings suggest a potential role of gut microbiota in the development of geriatric syndromes, providing valuable insights for further research into the causal relationship between gut microbiota and these syndromes.

Postoperative Delirium and the Older Adult: Untangling the Confusion

Postoperative delirium is one of the most prevalent postoperative complications, affecting mostly older adults. Its incidence is expected to rise because of surgical advances, shifting demographics, and increased life expectancy. Although an acute alteration in brain function, postoperative delirium is associated with adverse outcomes, including progressive cognitive decline and dementia, that place significant burdens on patients' lives and healthcare systems. This has prompted efforts to understand the mechanisms of postoperative delirium to provide effective prevention and treatment. There are multiple mechanisms involved in the etiology of postoperative delirium that share similarities with the physiological changes associated with the aging brain. In addition, older patients often have multiple comorbidities including increased cognitive impairment that is also implicated in the genesis of delirium. These tangled connections pinpointed a shift toward creation of a holistic model of the pathophysiology of postoperative delirium. Scientific advancements integrating clinical risk factors, possible postoperative delirium biomarkers, genetic features, digital platforms, and other biotechnical and information technological innovations, will become available in the near future. Advances in artificial intelligence, for example, will aggregate cognitive testing platforms with patient-specific postoperative delirium risk stratification studies, panels of serum and cerebrospinal fluid molecules, electroencephalogram signatures, and gut microbiome features, along with the integration of novel polygenetic variants of sleep and cognition. These advances will allow for the enrollment of high-risk patients into prevention programs and help uncover new pharmacologic targets.

Causal relationships between gut microbiota, immune cell, and Non-small cell lung cancer: a two-step, two-sample Mendelian randomization study

Background: Regulating the immune system is a crucial measure of gut microbiota (GM) that influences the development of diseases. The causal role of GM on Non-small cell lung cancer (NSCLC) and whether it can be mediated by immune cells is still unknown. Methods: We performed a two-step, two-sample Mendelian randomization study with an Inverse variance weighted (IVW) approach to investigate the causal role of GM on NSCLC and the mediation effect of immune cells between the association of GM and NSCLC. Results: MR analyses determined the protective effects of 6 genera on NSCLC (Bacteroides, Roseburia, Alistipes, Methanobrevibacter, Ruminococcus gauvreauii group, and Peptococcus). In addition, 38 immune cell traits were suggestively associated with NSCLC. Of note, the mediation MR illustrated the causal role of Genus-Peptococcus on NSCLC (Total effect IVW: OR = 0.790, 95% CI [0.657, 0.950], P = 0.012) was to a large proportion mediated by CD45 on HLA DR+ CD4+ in TBNK panel (-034 (95% CI [-0.070, -0.005]; P = 0.037), accounting for 14.4% of Total effect). Conclusion: The study suggested a causal relationship between GM and NSCLC, which may be mediated by immune cells.

Comparison of Helicobacter pylori positive and negative gastric cancer via multi-omics analysis

IMPORTANCE

This is the first clinical research to systematically expound the difference between gastric cancer (GC) individuals with Helicobacter pylori and GC individuals without H. pylori from the perspective of multi-omics. This clinical study identified significant genes, microbes, and fecal metabolites, which exhibited nice power for differentiating GC individuals with H. pylori infection from GC individuals without H. pylori infection. This study provides a crucial basis for a better understanding of eradication therapy among the GC population.

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.

The association between gut microbiota and postoperative delirium in patients

Postoperative delirium is a common postoperative complication in older patients, and its pathogenesis and biomarkers remain largely undetermined. The gut microbiota has been shown to regulate brain function, and therefore, it is vital to explore the association between gut microbiota and postoperative delirium. Of 220 patients (65 years old or older) who had a knee replacement, hip replacement, or laminectomy under general or spinal anesthesia, 86 participants were included in the data analysis. The incidence (primary outcome) and severity of postoperative delirium were assessed for two days. Fecal swabs were collected from participants immediately after surgery. The 16S rRNA gene sequencing was used to assess gut microbiota. Principal component analyses along with a literature review were used to identify plausible gut microbiota, and three gut bacteria were further studied for their associations with postoperative delirium. Of the 86 participants [age 71.0 (69.0-76.0, 25-75% percentile of quartile), 53% female], 10 (12%) developed postoperative delirium. Postoperative gut bacteria Parabacteroides distasonis was associated with postoperative delirium after adjusting for age and sex (Odds Ratio [OR] 2.13, 95% Confidence Interval (CI): 1.09-4.17, P = 0.026). The association between delirium and both Prevotella (OR: 0.59, 95% CI: 0.33-1.04, P = 0.067) and Collinsella (OR: 0.57, 95% CI: 0.27-1.24, P = 0.158) did not meet statistical significance. These findings suggest that there may be an association between postoperative gut microbiota, specifically Parabacteroides distasonis, and postoperative delirium. However, further research is needed to confirm these findings and better understand the gut-brain axis's role in postoperative outcomes.

The association between gut microbiota and postoperative delirium in patients

Postoperative delirium is one of the most common postoperative complications in older patients. Its pathogenesis and biomarkers, however, remain largely undetermined. Majority of human microbiota is gut microbiota and gut microbiota has been shown to regulate brain function. Therefore, this study aimed to determine the association between gut microbiota and postoperative delirium in patients. Of 220 patients (65 years old or older) who had a knee replacement, hip replacement, or laminectomy under general or spinal anesthesia, 86 participants were included in the data analysis. The incidence (primary outcome) and severity of postoperative delirium was assessed for two days. Fecal swabs were collected from participants immediately after surgery. The 16S rRNA gene sequencing was used to assess gut microbiota. Using principal component analyses along with a literature review to identify biologically plausible mechanisms, and three bacterials were studied for their associations with postoperative delirium. Of the 86 participants [age 71.0 (69.0-76.0, 25%-75% percentile of quartile), 53% female], ten (12%) developed postoperative delirium. Postoperative gut bacteria Parabacteroides distasonis (Odds Ratio [OR] 2.13, 95% Confidence Interval (CI): 1.09-4.17, P = 0.026) was associated with postoperative delirium after adjusting for age and sex. The association between delirium and both Prevotella (OR: 0.59, 95% CI: 0.33-1.04, P = 0.067) and Collinsella (OR: 0.57, 95% CI: 0.27-1.24, P = 0.158) did not meet statistical significance. These findings suggest that postoperative gut microbiota (e.g., Parabacteroides distasonis ) may serve as biomarkers in the pathogenesis of postoperative delirium, pending confirmative studies.

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.