Postoperative Complications Are Associated with Long-Term Changes in the Gut Microbiota Following Colorectal Cancer Surgery

Intestinal dysbiosis as an intraoperative predictor of septic complications: evidence from human surgical cohorts and preclinical models of peritoneal sepsis

Major surgery exposes the intestinal microbiota to inflammatory and antibiotic stressors, which alter the microbiota composition of the intestinal lumen and fecal contents. However, it is not sufficiently understood, if such dysbiosis develops already during surgery and if alterations in microbiota may be the cause of surgical complications. End-of-surgery composition of the microbiota in the rectum was assessed in 41 patients undergoing either rectal or duodenopancreatic resection and was compared to baseline before surgery using 16S-rRNA sequencing. A subset of patients developed severe dysbiosis at the end of surgery, which was characterized by an overgrowth of the Proteobacteria phylum that includes the facultative pathogen E. coli. To test if dysbiosis impacts on surgical outcomes, dysbiosis was modeled in mice by a single oral administration of vancomycin prior to cecal ligation and puncture. Dysbiosis was associated with impaired post-surgical survival, dysregulation of the host's immune response, elevated bacterial virulence and reduced bacterial metabolism of carbon sources. In conclusion, dysbiosis can be detected already at the end of surgery in a fraction of patients undergoing major surgery. Modelling surgery-associated dysbiosis in mice using single-shot administration of vancomycin induced dysbiosis and resulted in elevated mortality.

Diet-induced shifts in the gut microbiota influence anastomotic healing in a murine model of colonic surgery

Host diet and gut microbiota interact to contribute to perioperative complications, including anastomotic leak (AL). Using a murine surgical model of colonic anastomosis, we investigated how diet and fecal microbial transplantation (FMT) impacted the intestinal microbiota and if a predictive signature for AL could be determined. We hypothesized that a Western diet (WD) would impact gut microbial composition and that the resulting dysbiosis would correlate with increased rates of AL, while FMT from healthy, lean diet (LD) donors would reduce the risk of AL. Furthermore, we predicted that surgical outcomes would allow for the development of a microbial preclinical translational tool to identify AL. Here, we show that AL is associated with a dysbiotic microbial community characterized by increased levels of Bacteroides and Akkermansia. We identified several key taxa that were associated with leak formation, and developed an index based on the ratio of bacteria associated with the absence and presence of leak. We also highlight a modifiable connection between diet, microbiota, and anastomotic healing, potentially paving the way for perioperative modulation by microbiota-targeted therapeutics to reduce AL.

Effect of preoperative immunonutrition on fecal microbiota in colon cancer patients: a secondary analysis of a randomized controlled trial

BACKGROUND/OBJECTIVES

This study aimed to evaluate the effect of preoperative immunonutrition on the composition of fecal microbiota following a colon cancer surgery.

MATERIALS/METHODS

This study was a secondary analysis of a randomized controlled trial assessing the impact of preoperative immunonutrition on the postoperative outcomes of colon cancer surgery. Patients with primary colon cancer were enrolled and randomly assigned to receive additional preoperative immunonutrition or a normal diet alone. Oral nutritional supplementation (400 mL/day) with arginine and ω-3 fatty acids were administered to patients in the immunonutrition group for 7 days prior to surgery. Thirty-two fecal samples were collected from 16 patients in each group, and the composition of fecal microbiota was compared between the 2 groups.

RESULTS

At the phylum level, no significant difference was observed in the composition of microbiota between the 2 groups (Firmicutes, 69.1% vs. 67.5%, P = 0.624; Bacteroidetes, 19.3% vs. 18.1%, P = 0.663; Actinobacteria, 6.7% vs. 10.6%, P = 0.080). The Firmicutes/Bacteroidetes ratio (4.43 ± 2.32 vs. 4.55 ± 2.51, P = 0.897) was also similar between the 2 groups. At the genus level, the proportions of beneficial bacteria such as Faecalibacterium spp. (8.1% vs. 6.4%, P = 0.328) and Prevotella spp. (6.9% vs. 4.8%, P = 0.331) were higher, while that of Clostridium spp. was lower (0.5% vs. 1.2%, P = 0.121) in the immunonutrition group, but the difference was not significant.

CONCLUSIONS

Immunonutrition showed no significant association with the composition of fecal microbiota. The relationship between immunonutrition and the fecal microbiota should be investigated further in large-scale studies.

The implication of gut microbiota in recovery from gastrointestinal surgery

Recovery from gastrointestinal (GI) surgery is often interrupted by the unpredictable occurrence of postoperative complications, including infections, anastomotic leak, GI dysmotility, malabsorption, cancer development, and cancer recurrence, in which the implication of gut microbiota is beginning to emerge. Gut microbiota can be imbalanced before surgery due to the underlying disease and its treatment. The immediate preparations for GI surgery, including fasting, mechanical bowel cleaning, and antibiotic intervention, disrupt gut microbiota. Surgical removal of GI segments also perturbs gut microbiota due to GI tract reconstruction and epithelial barrier destruction. In return, the altered gut microbiota contributes to the occurrence of postoperative complications. Therefore, understanding how to balance the gut microbiota during the perioperative period is important for surgeons. We aim to overview the current knowledge to investigate the role of gut microbiota in recovery from GI surgery, focusing on the crosstalk between gut microbiota and host in the pathogenesis of postoperative complications. A comprehensive understanding of the postoperative response of the GI tract to the altered gut microbiota provides valuable cues for surgeons to preserve the beneficial functions and suppress the adverse effects of gut microbiota, which will help to enhance recovery from GI surgery.

Gut microbiome is associated with metabolic syndrome accompanied by elevated gamma-glutamyl transpeptidase in men

It is predicted that by 2035, metabolic syndrome (MS) will be found in nearly more than half of our adult population, seriously affecting the health of our body. MS is usually accompanied by the occurrence of abnormal liver enzymes, such as elevated gamma-glutamyl transpeptidase (GGT). More and more studies have shown that the gut microbiota is involved in MS; however, the correlation between gut microbiota and MS with elevated GGT has not been studied comprehensively. Especially, there are few reports about its role in the physical examination of the population of men with MS and elevated GGT. By using the whole-genome shotgun sequencing technology, we conducted a genome-wide association study of the gut microbiome in 66 participants diagnosed as having MS accompanied by high levels of GGT (case group) and 66 participants with only MS and normal GGT level (control group). We found that the number of gut microbial species was reduced in participants in the case group compared to that of the control group. The overall microbial composition between the two groups is of significant difference. The gut microbiota in the case group is characterized by increased levels of “harmful bacteria” such as Megamonas hypermegale, Megamonas funiformis, Megamonas unclassified, Klebsiella pneumoniae, and Fusobacterium mortiferum and decreased levels of “beneficial bacteria” such as Faecalibacterium prausnitzii, Eubacterium eligens, Bifidobacterium longum, Bifidobacterium pseudocatenulatum, Bacteroides dorei, and Alistipes putredinis. Moreover, the pathways of POLYAMSYN-PWY, ARG+POLYAMINE-SYN, PWY-6305, and GOLPDLCAT-PWY were also increased in the case group, which may play a role in the elevation of GGT by producing amine, polyamine, putrescine, and endogenous alcohol. Taken together, there are apparent changes in the composition of the gut microbiome in men with MS and abnormal GGT levels, and it is high time to discover specific gut microbiome as a potential therapeutic target in that population. More in-depth studies of relevant mechanism could offer some new methods for the treatment of MS with elevated GGT.

Current Insights: The Impact of Gut Microbiota on Postoperative Complications in Visceral Surgery-A Narrative Review

Postoperative complications are a major problem occurring in up to 50% of patients undergoing major abdominal surgery. Occurrence of postoperative complications is associated with a significantly higher morbidity and mortality in affected patients. The most common postoperative complications are caused by an infectious genesis and include anastomotic leakage in case of gastrointestinal anastomosis and surgical site infections. Recent research highlighted the importance of gut microbiota in health and disease. It is plausible that the gut microbiota also plays a pivotal role in the development of postoperative complications. This narrative review critically summarizes results of recent research in this particular field. The review evaluates the role of gut microbiota alteration in postoperative complications, including postoperative ileus, anastomotic leakage, and surgical site infections in visceral surgery. We tried to put a special focus on a potential diagnostic value of pre- and post-operative gut microbiota sampling showing that recent data are inhomogeneous to identify a high-risk microbial profile for development of postoperative complications.

The Association of Gut Microbiota and Complications in Gastrointestinal-Cancer Therapies

The therapy of gastrointestinal carcinomas includes surgery, chemo- or immunotherapy, and radiation with diverse complications such as surgical-site infection and enteritis. In recent years, the microbiome’s influence on different diseases and complications has been studied in more detail using methods such as next-generation sequencing. Due to the relatively simple collectivisation, the gut microbiome is the best-studied so far. While certain bacteria are sometimes associated with one particular complication, it is often just the loss of alpha diversity linked together. Among others, a strong influence of Fusobacterium nucleatum on the effectiveness of chemotherapies is demonstrated. External factors such as diet or specific medications can also predispose to dysbiosis and lead to complications. In addition, there are attempts to treat developed dysbiosis, such as faecal microbiota transplant or probiotics. In the future, the underlying microbiome should be investigated in more detail for a better understanding of the precipitating factors of a complication with specific therapeutic options.

SYNPO2 suppresses hypoxia-induced proliferation and migration of colorectal cancer cells by regulating YAP-KLF5 axis

Colorectal cancer (CRC) is one of the most common tumors that has a high incidence worldwide. Targeted therapy for CRC has received much attention recently. It is still necessary to develop novel and promising therapeutic targets to improve the prognosis. SYNPO2, also known as synapsopoprotein 2 or myopod, encodes actin binding proteins and has been characterized as a tumor suppressor for aggressive cancers. SYNPO2 has been reported to inhibit the activity of YAP/TAZ. However, whether SYNPO2 could regulate the progression of CRC through the YAP/YAZ signaling pathway remains unclear. Herein, it was found that the expression of SYNPO2 was low in hypoxia-exposed CRC cells, consistent with the data from TCGA database. SYNPO2 inhibited the growth of CRC cells upon hypoxia treatment and promoted the cell apoptosis. Additionally, SYNPO2 inhibited the migration and epithelial-mesenchymal transformation (EMT) CRC cell upon hypoxia treatment. Mechanically, the results demonstrated that SYNPO2 suppressed hypoxia-induced progression of CRC by regulating YAP-Kruppel like factor 5 (KLF5) axis. Therefore, SYNPO2 can serve as a promising therapeutic target for CRC treatment.