Predictive and Preventive Potential of Preoperative Gut Microbiota in Chronic Postoperative Pain in Breast Cancer Survivors

Guideline for designing microbiome studies in neoplastic diseases

Oncobiosis has emerged as a key contributor to the development, and modulator of the treatment efficacy of cancer. Hereby, we review the modalities through which the oncobiome can support the progression of tumors, and the emerging therapeutic opportunities they present. The review highlights the inherent challenges and limitations faced in sampling and accurately characterizing oncobiome. Additionally, the review underscores the critical need for the standardization of microbial analysis techniques and the consistent reporting of microbiome data. We provide a suggested metadata set that should accompany microbiome datasets from oncological settings so that studies remain comparable and decipherable.

Gut Microbiota and Probiotics in Perioperative Management: A Narrative Review

The human gut is the abode of several complex and diverse microbes. It is a fact that the human brain is interconnected with the spinal cord and sense organs; however, there is also a possibility of a connection between the brain and the gut microbiome. The human gut can be altered in various ways, the principal method being the intake of prebiotics, probiotics and synbiotics. Can this alteration in the gut microbiome be clinically utilised in the perioperative period? We conducted a literature search related to this topic using databases and search engines (Medical Literature Analysis and Retrieval System Online {MEDLINE}, Embase, Scopus, PubMed and Google Scholar). The search revealed some preclinical and clinical studies in animals and humans that demonstrate the alteration of the gut microbiome with the use of anxiolysis, probiotics/prebiotics and other perioperative factors including opioids, anaesthetics and perioperative stress. The significant effects of this alteration have been seen on preoperative anxiety and postoperative delirium/cognitive dysfunction/pain. These effects are described in this narrative review, which opens up newer vistas for high-quality research related to the gut microbiome, gut-brain axis, the related signaling pathways and their clinical application in the perioperative period.

Gut microbiota promotes pain chronicity in Myosin1A deficient male mice

Chronic pain is a heavily debilitating condition and a huge socio-economic burden, with no efficient treatment. Over the past decade, the gut microbiota has emerged as an important regulator of nervous system's health and disease states. Yet, its contribution to the pathogenesis of chronic somatic pain remains poorly documented. Here, we report that male but not female mice lacking Myosin1a (KO) raised under single genotype housing conditions (KO-SGH) are predisposed to develop chronic pain in response to a peripheral tissue injury. We further underscore the potential of MYO1A loss-of-function to alter the composition of the gut microbiota and uncover a functional connection between the vulnerability to chronic pain and the dysbiotic gut microbiota of KO-SGH males. As such, parental antibiotic treatment modifies gut microbiota composition and completely rescues the injury-induced pain chronicity in male KO-SGH offspring. Furthermore, in KO-SGH males, this dysbiosis is accompanied by a transcriptomic activation signature in the dorsal root ganglia (DRG) macrophage compartment, in response to tissue injury. We identify CD206+CD163- and CD206+CD163+ as the main subsets of DRG resident macrophages and show that both are long-lived and self-maintained and exhibit the capacity to monitor the vasculature. Consistently, in vivo depletion of DRG macrophages rescues KO-SGH males from injury-induced chronic pain underscoring a deleterious role for DRG macrophages in a Myo1a-loss-of function context. Together, our findings reveal gene-sex-microbiota interactions in determining the predisposition to injury-induced chronic pain and point-out DRG macrophages as potential effector cells.

Chronic pain and complex regional pain syndrome are associated with alterations to the intestinal microbiota in both humans and mice. An observational cross-sectional study

Objective

This study aimed to evaluate pain metrics and gut microbiota differences from human subjects with complex regional pain syndrome (CRPS) compared to cohabitants (HHC) and non-cohabitating (biobank) controls. In addition, we aimed evaluate longitudinal changes of gut microbiota using a mouse model of acute and chronic CRPS.

Methods

In an observational, cross-sectional study, 25 patients with CRPS and 24 household controls (HHC) were recruited, completed pain questionnaires, and submitted stool samples. 23 biobank stool samples were matched to the CRPS group. Additionally, longitudinal stool samples were collected from a mouse model of acute and chronic CRPS. 16S rRNA gene sequencing analysis was performed on all samples.

Results

A diagnosis of CRPS is associated with higher pain, increased pain interference, and decreased physical and social function when compared to HHC. Interestingly, 46% of HHC reported significant daily pain. In the households where HHC were also suffering from pain, there was decreased bacterial richness and diversity when compared to households wherein only the participant with CRPS suffered from pain. Furthermore, when comparing households where the HHC had significant pain, CRPS was clinically more severe. In the mouse model of CRPS, we observed decreased bacterial richness and diversity when compared to non-cohabitating littermate controls.

Conclusions

Both humans living in chronic pain households and mice shared distinct taxa over the time course of disease and pain chronicity. These findings suggest that microbiota changes seen in CRPS as well as in a mouse model of CRPS may reflect pain chronicity and may indicate that pain alone can contribute to microbiota dysbiosis. The trial was registered at ClinicalTrials.gov (NCT03612193).

Preoperative resting-state microstate as a marker for chronic pain after breast cancer surgery

INTRODUCTION

Chronic postoperative pain poses challenges, emphasizing the importance of accurately predicting pain in advance. Generally, pain perception is associated with the temporal dynamics of the brain, which can be represented by microstates. Specifically, microstates are transient and patterned brain topographies formed by temporally overlapping and spatially synchronized oscillatory activities. Consequently, by characterizing brain activity, microstates offer valuable insights into pain perception.

METHODS

In this prospective study, 66 female patients undergoing breast cancer surgery were included. Their preoperative resting-state electroencephalography (EEG) was recorded. Preoperative resting-state EEG was recorded and four specific brain microstates (labeled as A, B, C, and D) were extracted. Temporal characteristics were then analyzed from these microstates. Patients were classified into two groups based on their Numerical Rating Scale (NRS) scores at three months postoperatively. Those with NRS scores ranging from 4 to 10 were classified as the high pain group, while patients with NRS ranging from 0 to 3 were classified as the lowpain group. Statistical analyses were performed to compare the microstate characteristics between these two groups.

RESULTS

Twenty-one patients (32%) were classified as the high pain group and forty-five (68%) as the low-pain group. The occurrence and coverage of microstate C were significantly higher in the high pain group. Additionally, there were significant differences in the microstates transitions between the two groups. Furthermore, the study revealed a positive correlation between the coverage of microstate C and the NRS.

CONCLUSIONS

Preoperative resting-state microstate features have shown correlations with postoperative pain. This study presents a novel and advanced perspective on the potential of microstates as a marker for postoperative pain.

Global Trends in Research of Pain-Gut-Microbiota Relationship and How Nutrition Can Modulate This Link

INTRODUCTION

The link between gut microbiota and chronic painful conditions has recently gained attention. Nutrition, as a common intervention in daily life and medical practice, is closely related to microbiota and pain. However, no published bibliometric reports have analyzed the scientific literature concerning the link.

METHODS AND RESULTS

We used bibliometrics to identify the characteristics of the global scientific output over the past 20 years. We also aimed to capture and describe how nutrition can modulate the abovementioned link. Relevant papers were searched in the Web of Science database. All necessary publication and citation data were acquired and exported to Bibliometrix for further analyses. The keywords mentioned were illustrated using visualization maps. In total, 1551 papers shed light on the relationship from 2003 to 2022. However, only 122 papers discussed how nutritional interventions can modulate this link. The citations and attention were concentrated on the gut microbiota, pain, and probiotics in terms of the pain-gut relationship. Nutritional status has gained attention in motor themes of a thematic map.

CONCLUSIONS

This bibliometric analysis was applied to identify the scientific literature linking gut microbiota, chronic painful conditions, and nutrition, revealing the popular research topics and authors, scientific institutions, countries, and journals in this field. This study enriches the evidence moving boundaries of microbiota medicine as a clinical medicine.

Preoperative frailty assessment could be a predictive factor for the prognosis of elderly patients undergoing coronary artery bypass grafting: a retrospective case-control study

BACKGROUND

Frailty has been considered to be associated with major mortality and increased length of stay after cardiac surgery. This study aimed to explore the predictive potential of frailty assessment in the prognosis of elderly patients undergoing bypass surgery.

METHODS

This study assessed the preoperative frailty according to the Fried's frailty phenotype, and included 150 frail and 150 non-frail elderly patients (≥ 65 y) who underwent bypass surgery. The present study evaluated the prognosis of elderly patients based on sequential organ failure assessment (SOFA) score, and collected clinical indicators to construct logistic regression models with the prognosis as the dependent variable, to explore the potential predictive ability of preoperative frailty. Moreover, this study focused on the complications and analyzed the relationship between preoperative frailty and postoperative complications.

RESULTS

In the present study, 244 patients were divided into the favorable prognosis group and 56 patients were divided into the unfavorable prognosis group. Logistic regression analysis showed that increased myoglobin and high cardiac function classification were independent risk factors for unfavorable prognosis in elderly patients undergoing bypass surgery. The discrimination of the clinical prediction model was determined by the receiver operating characteristic (ROC) curve, and the area under curve (AUC) was 0.928. After adding preoperative frailty assessment, the AUC was improved to 0.939. This study found a significant correlation between preoperative frailty and postoperative complications, mainly in the circulatory system.

CONCLUSION

Preoperative frailty assessment could be a predictive factor for the prognosis of elderly patients undergoing coronary artery bypass grafting. According to our study, frailty assessment and appropriate intervention before bypass surgery may be beneficial to the enhanced recovery after cardiac surgery.

TRIAL REGISTRATION

The clinical study was approved by the Medical Ethics Committee of The First Affiliated Hospital of Nanjing Medical University (2021-SR-393). All patients signed an informed consent form.

The gut microbiota in breast cancer development and treatment: The good, the bad, and the useful!

Regardless of the global progress in early diagnosis and novel therapeutic regimens, breast carcinoma poses a devastating threat, and the advances are somewhat marred by high mortality rates. Breast cancer risk prediction models based on the known risk factors are extremely useful, but a large number of breast cancers develop in women with no/low known risk. The gut microbiome exerts a profound impact on the host health and physiology and has emerged as a pivotal frontier in breast cancer pathogenesis. Progress in metagenomic analysis has enabled the identification of specific changes in the host microbial signature. In this review, we discuss the microbial and metabolomic changes associated with breast cancer initiation and metastatic progression. We summarize the bidirectional impact of various breast cancer-related therapies on gut microbiota and vice-versa. Finally, we discuss the strategies to modulate the gut microbiota toward a more favorable state that confers anticancer effects.

Gut Microbiome in Anesthesiology and Pain Medicine

The gut microbiome plays critical roles in human health and disease. Recent studies suggest it may also be associated with chronic pain and postoperative pain outcomes. In animal models, the composition of the gut microbiome changes after general anesthesia and affects the host response to medications, including anesthetics and opioids. In humans, the gut microbiome is associated with the development of postoperative pain and neurocognitive disorders. Additionally, the composition of the gut microbiome has been associated with pain conditions including visceral pain, nociplastic pain, complex regional pain syndrome, and headaches, partly through altered concentration of circulating bacterial-derived metabolites. Furthermore, animal studies demonstrate the critical role of the gut microbiome in neuropathic pain via immunomodulatory mechanisms. This article reviews basic concepts of the human gut microbiome and its interactions with the host and provide a comprehensive overview of the evidence linking the gut microbiome to anesthesiology, critical care, and pain medicine.