Gut microbiota in patients after surgical treatment for colorectal cancer

Impacts of microplastics on gut health: Current status and future directions

BACKGROUND AND OBJECTIVES

Microplastics are pervasive environmental pollutants, attracting significant concern due to their potential adverse effects on ecosystems and human health. This study hypothesizes that microplastics may significantly impact gastrointestinal (GI) health through various mechanisms. The objective of this systematic review is to explore the effects of microplastics on GI health, focusing on animal models such as mice, fish and earthworms.

METHODS

A systematic review approach was employed, analyzing studies that investigate the impact of microplastics on the gut microbiota, gut barrier integrity and GI inflammation. The review includes a synthesis of findings from multiple animal models.

RESULTS

The review reveals consistent evidence that microplastics can disrupt the gut microbiota, impair the gut barrier, and induce inflammatory responses in the GI tract. Statistical analysis shows a significant correlation between microplastic exposure and GI health deterioration across various animal models.

CONCLUSIONS

The findings underscore the harmful effects of microplastics on GI health, emphasizing the urgent need for policy interventions to reduce plastic pollution. Implementing measures to limit the production and usage of disposable plastics is crucial for mitigating the risks posed by microplastic contamination to promote environmental sustainability and safeguard human well-being.

Gut microbiota alterations in colorectal adenoma-carcinoma sequence based on 16S rRNA gene sequencing: A systematic review and meta-analysis

BACKGROUND

Most sporadic colorectal cancers (CRC) develop through the adenoma-carcinoma sequence. While dysbiosis of the intestinal flora contributes to CRC's pathogenesis, precise microbial taxa closely associated with the colorectal adenoma-carcinoma sequence remain elusive. This meta-analysis aimed to summarize the features of intestinal flora in patients with AD and CRC.

METHODS

PubMed, Embase, Cochrane Library, and Web of Science were searched for case-control studies comparing the relative abundance of gut microbiota in the feces of patients with AD, CRC, and healthy controls (HC) from inception to January 2024. The weighted mean difference (WMD) with a 95 % confidence interval (CI) was used to display the results. The Newcastle-Ottawa Scale (NOS) was used to assess the quality of the entailed literature. Publication bias was evaluated with the Egger's and Begg's tests.

RESULTS

Eleven studies were included, involving 477 CRC patients, 628 AD patients, and 864 healthy controls. Compared with HC, the patients with AD had a significantly lower Chao 1 index (WMD = -30.17, 95 % CI [-41.10, -19.23], P < 0.001) and Shannon index (WMD = -0.11 95 % CI [-0.18, -0.04], P = 0.002). Compared with AD, the CRC patients had a significantly higher Chao1 index (WMD = 22.09, 95 % CI [7.59, 36.00], P = 0.003) and Shannon index (WMD = 0.08, 95 % CI [0.00, 0.15], P = 0.037). Enterobacteriaceae (WMD = 0.03 95 % CI [0.00,0.05], P = 0.047; WMD = 0.02 95 % CI [0.00,0.04], P = 0.027) significantly increased in the order of Control-AD-CRC, while that of Blautia (WMD = -0.00 95 % CI [-0.01, -0.00], P = 0.001; WMD = -0.00 95 % CI [-0.00, -0.00], P = 0.002) was reduced. Compared with HC, the relative abundance of Proteobacteria (WMD = 0.05 95 % CI [0.03,0.07], P < 0.001), Fusobacteria (WMD = 0.02 95 % CI [0.00,0.03], P = 0.042), Streptococcaceae (WMD = 0.03 95 % CI [0.01,0.05], P = 0.017), Prevotellaceae (WMD = 0.02 95 % CI [0.00,0.04], P = 0.040), and Escherichia-Shigella (WMD = 0.06 95 % CI [0.01, 0.11], P = 0.021) was enriched in the CRC group. The relative abundance of Alistipes (WMD = 0.00 95 % CI [0.00,0.01], P = 0.032) and Streptococcus (WMD = 0.00 95 % CI [0.00,0.00], P = 0.001) was increased in the AD vs HC. The relative abundance of Firmicutes (WMD = -0.07 95 % CI [-0.12, -0.03], P = 0.003), Bifidobacteria (WMD = -0.03 95 % CI [-0.05, -0.01], P = 0.016), and Klebsiella (WMD = -0.01 95 % CI [-0.01, -0.00], P = 0.001) was decreased in the CRC vs HC. Compared with AD, the relative abundance of Firmicutes (WMD = -0.04 95 % CI [-0.07, -0.02], P = 0.002), Peptostreptococcaceae (WMD = -0.03 95 % CI [-0.05, -0.00], P = 0.021), Lachnospiraceae (WMD = -0.04 95 % CI [-0.08,-0.00], P = 0.037), Ruminococcaceae (WMD = -0.06 95 % CI [-0.09,-0.03], P < 0.001), Faecalibacterium (WMD = -0.01 95 % CI [-0.02, -0.01], P = 0.001), and Lachnoclostridium (WMD = -0.02 95 % CI [-0.03, -0.00], P = 0.040) was decreased in the CRC group, while Proteobacteria (WMD = 0.04 95 % CI [0.02,0.05], P < 0.001) was increased.

CONCLUSIONS

The dysbiosis characterized by reduced levels of short-chain fatty acid (SCFA)-producing bacteria, decreased anti-inflammatory bacteria, increased pro-inflammatory bacteria, and an elevation of bacteria with cytotoxic effects damaging to DNA may represent the specific microbial signature of colorectal adenoma/carcinoma. Further research is required to elucidate the mechanisms by which gut dysbiosis leads to the progression from AD to CRC and to explore the potential of specific microbiota markers in clinical treatment and non-invasive screening.

Impact of mechanical bowel preparation on the gut microbiome of patients undergoing left-sided colorectal cancer surgery: randomized clinical trial

BACKGROUND

Postoperative complications after colorectal cancer surgery have been linked to the gut microbiome. However, the impact of mechanical bowel preparation using oral preparation agents or rectal enema on postoperative infections remains poorly understood. This study aimed to compare the impact of oral preparation and rectal enema on the gut microbiome and postoperative complications.

METHODS

This open-label pilot RCT was conducted at the National Cancer Institute, Vilnius, Lithuania. Patients with left-side colorectal cancer scheduled for elective resection with primary anastomosis were randomized 1 : 1 to preoperative mechanical bowel preparation with either oral preparation or rectal enema. Stool samples were collected before surgery, and on postoperative day 6 and 30 for 16S rRNA gene sequencing analysis. The primary outcome was difference in β-diversity between groups on postoperative day 6.

RESULTS

Forty participants were randomized to oral preparation (20) or rectal enema (20). The two groups had similar changes in microbiome composition, and there was no difference in β-diversity on postoperative day 6. Postoperative infections occurred in 12 patients (32%), without differences between the study groups. Patients with infections had an increased abundance of bacteria from the Actinomycetaceae family, Actinomyces genus, Sutterella uncultured species, and Enterococcus faecalis species.

CONCLUSION

Mechanical bowel preparation with oral preparation or rectal enema resulted in similar dysbiosis. Patients who experienced postoperative infections exhibited distinct gut microbiome compositions on postoperative day 6, characterized by an increased abundance of bacteria from the Actinomycetaceae family, Actinomyces genus, Sutterella uncultured species, and Enterococcus faecalis species.

REGISTRATION NUMBER

NCT04013841 (http://www.clinicaltrials.gov).

Antibiotic use during radical surgery in stage I-III colorectal cancer: correlation with outcomes?

AIMS

Accumulating evidence indicates that the use of antibiotics (ATBs) in cancer patients is potentially correlated with patient prognosis. Interestingly, the use of these agents is not uncommon in colorectal cancer (CRC) patients during surgery; however, their prognostic value in the clinic has never been addressed.

MATERIALS AND METHODS

Data on ATB use during surgery, including the cumulative defined daily dose (cDDD) and the number of categories, were collected. Differences in the clinical data between the low and high cDDD subgroups and between subgroups with ≤ 4 and >4 categories. Additionally, the disease-free survival (DFS) and overall survival (OS) among these subgroups and the specific categories were compared. Finally, a Cox proportional hazard model was used to validate the risk factors for the outcome.

RESULTS

The number of categories, rather than the cDDD, was a significant predictor of both DFS (P = 0.043) and OS (P = 0.039). Patients with obstruction are more likely to have a high cDDD, whereas older patients are more likely to have multiple categories. There were no significant differences in the DFS (log rank = 1.36, P = 0.244) or OS (log rank = 0.40, P = 0.528) between patients in the low- and high-cDDD subgroups, whereas patients with ≤ 4 categories had superior DFS (log rank = 9.92, P = 0.002) and OS (log rank = 8.30, P = 0.004) compared with those with >4 categories. Specifically, the use of quinolones was harmful to survival (DFS: log rank = 3.67, P = 0.055; OS: log rank = 5.10, P = 0.024), whereas the use of macrolides was beneficial to survival (DFS: log rank = 12.26, P < 0.001; OS: log rank = 9.77, P = 0.002). Finally, the number of categories was identified as an independent risk factor for both DFS (HR = 2.05, 95% CI: 1.35-3.11, P = 0.001) and OS (HR = 1.82, 95% CI: 1.14-2.90, P = 0.012).

CONCLUSIONS

The cDDD of ATBs during surgery in stage I-III CRC patients did not correlate with outcome; however, patients in multiple categories or a specific category are likely to have inferior survival. These results suggest that particular caution should be taken when selecting ATBs for these patients in the clinic.

Gut microbiota characteristics of colorectal cancer patients in Hubei, China, and differences with cohorts from other Chinese regions

The research on the correlation or causality between gut microbiota and the occurrence, development, and treatment of colorectal cancer (CRC) is receiving increasing emphasis. At the same time, the incidence and mortality of colorectal cancer vary among individuals and regions, as does the gut microbiota. In order to gain a better understanding of the characteristics of the gut microbiota in CRC patients and the differences between different regions, we initially compared the gut microbiota of 25 CRC patients and 26 healthy controls in the central region of China (Hubei Province) using 16S rRNA high-throughput sequencing technology. The results showed that Corynebacterium, Enterococcus, Lactobacillus, and Escherichia-Shigella were significantly enriched in CRC patients. In addition, we also compared the potential differences in functional pathways between the CRC group and the healthy control group using PICRUSt's functional prediction analysis. We then analyzed and compared it with five cohort studies from various regions of China, including Central, East, and Northeast China. We found that geographical factors may affect the composition of intestinal microbiota in CRC patients. The composition of intestinal microbiota is crucial information that influences colorectal cancer screening, early detection, and the prediction of CRC treatment outcomes. This emphasizes the importance of conducting research on CRC-related gut microbiota in various regions of China.

Gut Microbial and Associated Metabolite Markers for Colorectal Cancer Diagnosis

Globally, colorectal cancer (CRC) is the second most common cause of mortality worldwide. Considerable evidence indicates that dysbiosis of the gut microbial community and its metabolite secretions play a fundamental role in advanced adenoma (ADA) and CRC development and progression. This study is a systematic review that aims to assess the clinical association between gut microbial markers and/or gut and circulating metabolites with ADA and CRC. Five electronic databases were searched by four independent reviewers. Only controlled trials that compared ADA and/or CRC with healthy control (HC) using either untargeted (16s rRNA gene or whole genome sequencing) or targeted (gene-based real-time PCR) identification methods for gut microbiome profile, or untargeted or targeted metabolite profiling approaches from the gut or serum/plasma, were eligible. Three independent reviewers evaluated the quality of the studies using the Cochrane Handbook for Systematic Reviews of Interventions. Twenty-four studies were eligible. We identified strong evidence of two microbial markers Fusobacterium and Porphyromonas for ADA vs. CRC, and nine microbial markers Lachnospiraceae-Lachnoclostridium, Ruminococcaceae-Ruminococcus, Parvimonas spp., Parvimonas micra, Enterobacteriaceae, Fusobacterium spp., Bacteroides, Peptostreptococcus-Peptostreptococcus stomatis, Clostridia spp.-Clostridium hylemonae, Clostridium symbiosum, and Porphyromonas-Porphyromonas asaccharolytica for CRC vs. HC. The remaining metabolite marker evidence between the various groups, including ADA vs. HC, ADA vs. HC, and CRC vs. HC, was not of sufficient quality to support additional findings. The identified gut microbial markers can be used in a panel for diagnosing ADA and/or CRC. Further research in the metabolite markers area is needed to evaluate the possibility to use in diagnostic or prognostic markers for colorectal cancer.

Indole metabolites and colorectal cancer: Gut microbial tryptophan metabolism, host gut microbiome biomarkers, and potential intervention mechanisms

Tryptophan (Trp) functions in host-disease interactions. Its metabolism is a multi-pathway process. Indole and its derivatives are Trp metabolites unique to the human gut microbiota. Changes in Trp metabolism have also been detected in colorectal cancer (CRC). Here, combined with the existing CRC biomarkers, we ascribed it to the altered bacteria having the indole-producing ability by making a genomic prediction. We also reviewed the anti-inflammatory and possible anti-cancer mechanisms of indoles, including their effects on tumor cells, the ability to repair the gut barrier, regulation of the host immune system, and provide resistance against oxidative stress. Indole and its derivatives, along with related bacteria, could be targeted as auxiliary strategies to restrain cancer development in the future.

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.

Colorectal cancer and gut microbiota studies in China

Colorectal cancer (CRC) is the third most common malignant tumor worldwide. The incidence and mortality rates of CRC have been increasing in China, possibly due to economic development, lifestyle, and dietary changes. Evidence suggests that gut microbiota plays an essential role in the tumorigenesis of CRC. Gut dysbiosis, specific pathogenic microbes, metabolites, virulence factors, and microbial carcinogenic mechanisms contribute to the initiation and progression of CRC. Gut microbiota biomarkers have potential translational applications in CRC screening and early diagnosis. Gut microbiota-related interventions could improve anti-tumor therapy's efficacy and severe intestinal toxic effects. Chinese researchers have made many achievements in the relationship between gut microbiota and CRC, although some challenges remain. This review summarizes the current evidence from China on the role of gut microbiota in CRC, mainly including the gut microbiota characteristics, especially Fusobacterium nucleatum and Parvimonas micra, which have been identified to be enriched in CRC patients; microbial pathogens such as F. nucleatum and enterotoxigenic Bacteroides fragilis, and P. micra, which Chinese scientists have extensively studied; diagnostic biomarkers especially F. nucleatum; therapeutic effects, including microecological agents represented by certain Lactobacillus strains, fecal microbiota transplantation, and traditional Chinese medicines such as Berberine and Curcumin. More efforts should be focused on exploring the underlying mechanisms of microbial pathogenesis of CRC and providing novel gut microbiota-related therapeutic and preventive strategies.

Characteristics of gut microbiota in patients with gastric cancer by surgery, chemotherapy and lymph node metastasis

BACKGROUND

Gastric cancer (GC) is a malignant gastrointestinal tumor that can result in high mortality. Surgery and chemotherapy are often used for the effective treatment of GC. In addition, lymph node metastasis is a significant factor affecting the therapy of GC. Current researches have revealed that gut microbiota has the potential as biomarkers to distinguish healthy people and GC patients. However, the relationship between surgery, chemotherapy, and lymph node metastasis is still unclear.

METHODS

In this study, 16S rRNA sequencing was used to investigate 157 GC fecal samples to identify the role of surgery, chemotherapy, and lymph node metastasis. Immunohistochemical analysis was used to value the expression of Ki67, HER2 in GC patient tissues.

RESULTS

There exist some gut microbiotas which can distinguish surgery from non-surgery GC patients, including Enterococcus, Megasphaera, Corynebacterium, Roseburia, and Lachnospira. Differences between lymph node metastasis and chemotherapy in GC patients are not significant. Moreover, we found the abundance of Blautia, Ruminococcus, Oscillospira were related to the expression of Ki67 and the abundance of Prevotella, Lachnospira, Eubacterium, Desulfovibiro were correlated with the expression of HER2.

CONCLUSIONS

The choice of treatment has a certain impact on the intestinal flora of patients with gastric cancer. Our research shows that surgery has a great effect on the intestinal flora of patients with gastric cancer. However, there were no significant differences in the characteristics of intestinal flora in patients with gastric cancer whether they received chemotherapy or whether they had lymph node metastasis. In addition, the association of gut microbiota with Ki67 and HER2 indicators is expected to provide the possibility of gut microbiota as a tumor prognostic marker.

Nutrition-wide association study of microbiome diversity and composition in colorectal cancer patients

BACKGROUND

The effects of diet on the interaction between microbes and host health have been widely studied. However, its effects on the gut microbiota of patients with colorectal cancer (CRC) have not been elucidated. This study aimed to investigate the association between diet and the overall diversity and different taxa levels of the gut microbiota in CRC patients via the nutrition-wide association approach.

METHODS

This hospital-based study utilized data of 115 CRC patients who underwent CRC surgery in Department of Surgery, Seoul National University Hospital. Spearman correlation analyses were conducted for 216 dietary features and three alpha-diversity indices, Firmicutes/Bacteroidetes ratio, and relative abundance of 439 gut microbial taxonomy. To identify main enterotypes of the gut microbiota, we performed the principal coordinate analysis based on the β-diversity index. Finally, we performed linear regression to examine the association between dietary intake and main microbiome features, and linear discriminant analysis effect size (LEfSe) to identify bacterial taxa phylogenetically enriched in the low and high diet consumption groups.

RESULTS

Several bacteria were enriched in patients with higher consumption of mature pumpkin/pumpkin juice (ρ, 0.31 to 0.41) but lower intake of eggs (ρ, -0.32 to -0.26). We observed negative correlations between Bacteroides fragilis abundance and intake of pork (belly), beef soup with vegetables, animal fat, and fatty acids (ρ, -0.34 to -0.27); an inverse correlation was also observed between Clostridium symbiosum abundance and intake of some fatty acids, amines, and amino acids (ρ, -0.30 to -0.24). Furthermore, high intake of seaweed was associated with a 6% (95% CI, 2% to 11%) and 7% (95% CI, 2% to 11%) lower abundance of Rikenellaceae and Alistipes, respectively, whereas overall beverage consumption was associated with an 10% (95% CI, 2% to 18%) higher abundance of Bacteroidetes, Bacteroidia, and Bacteroidales, compared to that in the low intake group. LEfSe analysis identified phylogenetically enriched taxa associated with the intake of sugars and sweets, legumes, mushrooms, eggs, oils and fats, plant fat, carbohydrates, and monounsaturated fatty acids.

CONCLUSIONS

Our data elucidates the diet-microbe interactions in CRC patients. Additional research is needed to understand the significance of these results in CRC prognosis.

A systematic review of microbial markers for risk prediction of colorectal neoplasia

BACKGROUND

Substantial evidence indicates that dysbiosis of the gut microbial community is associated with colorectal neoplasia. This review aims to systematically summarise the microbial markers associated with colorectal neoplasia and to assess their predictive performance.

METHODS

A comprehensive literature search of MEDLINE and EMBASE databases was performed to identify eligible studies. Observational studies exploring the associations between microbial biomarkers and colorectal neoplasia were included. We also included prediction studies that constructed models using microbial markers to predict CRC and adenomas. Risk of bias for included observational and prediction studies was assessed.

RESULTS

Forty-five studies were included to assess the associations between microbial markers and colorectal neoplasia. Nine faecal microbiotas (i.e., Fusobacterium, Enterococcus, Porphyromonas, Salmonella, Pseudomonas, Peptostreptococcus, Actinomyces, Bifidobacterium and Roseburia), two oral pathogens (i.e., Treponema denticola and Prevotella intermedia) and serum antibody levels response to Streptococcus gallolyticus subspecies gallolyticus were found to be consistently associated with colorectal neoplasia. Thirty studies reported prediction models using microbial markers, and 83.3% of these models had acceptable-to-good discrimination (AUROC > 0.75). The results of predictive performance were promising, but most of the studies were limited to small number of cases (range: 9-485 cases) and lack of independent external validation (76.7%).

CONCLUSIONS

This review provides insight into the evidence supporting the association between different types of microbial species and their predictive value for colorectal neoplasia. Prediction models developed from case-control studies require further external validation in high-quality prospective studies. Further studies should assess the feasibility and impact of incorporating microbial biomarkers in CRC screening programme.

Understanding the Role of the Microbiome in Cancer Diagnostics and Therapeutics by Creating and Utilizing ML Models

Recent studies have highlighted that gut microbiota can alter colorectal cancer susceptibility and progression due to its impact on colorectal carcinogenesis. This work represents a comprehensive technical approach in modeling and interpreting the drug-resistance mechanisms from clinical data for patients diagnosed with colorectal cancer. To accomplish our aim, we developed a methodology based on evaluating high-performance machine learning models where a Python-based random forest classifier provides the best performance metrics, with an overall accuracy of 91.7%. Our approach identified and interpreted the most significant genera in the cases of resistant groups. Thus far, many studies point out the importance of present genera in the microbiome and intend to treat it separately. The symbiotic bacterial analysis generated different sets of joint feature combinations, providing a combined overview of the model’s predictiveness and uncovering additional data correlations where different genera joint impacts support the therapy-resistant effect. This study points out the different perspectives of treatment since our aggregate analysis gives precise results for the genera that are often found together in a resistant group of patients, meaning that resistance is not due to the presence of one pathogenic genus in the patient microbiome, but rather several bacterial genera that live in symbiosis.

Colorectal microbiota after removal of colorectal cancer

The colonic microbiome has been implicated in the pathogenesis of colorectal cancer (CRC) and intestinal microbiome alterations are not confined to the tumour. Since data on whether the microbiome normalises or remains altered after resection of CRC are conflicting, we studied the colonic microbiota of patients after resection of CRC. We profiled the microbiota using 16S rRNA gene amplicon sequencing in colonic biopsies from patients after resection of CRC (n = 63) in comparison with controls (n = 52), subjects with newly diagnosed CRC (n = 93) and polyps (i = 28). The colonic microbiota after surgical resection remained significantly different from that of controls in 65% of patients. Genus-level profiling and beta-diversity confirmed two distinct groups of patients after resection of CRC: one with an abnormal microbiota similar to that of patients with newly diagnosed CRC and another similar to non-CRC controls. Consumption levels of several dietary ingredients and cardiovascular drugs co-varied with differences in microbiota composition suggesting lifestyle factors may modulate differential microbiome trajectories after surgical resection. This study supports investigation of the colonic microbiota as a marker of risk for development of CRC.

Operable hepatitis B virus-related hepatocellular carcinoma: gut microbiota profile of patients at different ages

Background

Age was important prognostic factors for operable hepatocellular carcinoma patients. The aim of the present study was to assess the difference in gut microbiota in patients with operable hepatitis B virus-related hepatocellular carcinoma (HBV-HCC) at different ages ; to investigate the features of the microbiota and its function associated with different ages; to provide a preliminary look at effects of the gut microbiota dimension on prognostic.

Methods

From September 2020 to May 2021, patients with HBV-HCC were able to undergo liver resection and were recruited consecutively and divided into the younger age group (age <45 years) (Y.AG) (n=20), middle age group (age from 45 to 65 years) (M.AG) (n=13) 45–65 years, and older age group (age >65 years) (O.AG) (n=20). The relationships between gut microbiota and different ages were explored using 16S rRNA gene sequencing data. PICRUST2 was used to examine the metagenomic data in PHLF patients. Fisher’s exact and Mann-Whitney U-test were used for the data analysis.

Results

Pairwise comparison between the three groups showed that the α-diversity of Y.AG was significantly higher than that of O.AG (ACE Index, P=0.017; chao1 Index, P=0.031; observed_species Index, P=0.011; and goods_coverage Index, P=0.041). The β-diversity in the 3 groups differed significantly (stress =0.100), while the composition (β-diversity) differed significantly between the Y.AG and the M.AG (stress =0.090), the M.AG and the O.AG (stress =0.095), and the Y.AG and the O.AG (stress =0.099). At the genus level, 7 bacterial genera were significantly enriched in the O.AG compared with the Y.AG, of which Streptococcus, Blautia, Erysipelotrichaceae_UCG-003, and Fusicatenibacter represented the major variances in O.AG microbiomes. Eleven genera were significantly increased in the O.AG, of which Prevotella, Allorhizobium-Neorhizobium-Pararhizobium-Rhizobium, Ruminiclostridium, and Phascolarctobacterium represented the major variances in the O.AG. The Y.AG and the O.AG were predicted by PICRUSt2 analysis, which found 72 pathways related to differential gut microbiome at the genus level. Redundancy analysis showed that 7 environmental factors were significantly correlated with intestinal microorganisms, especially in the Y.AG compared with the O.AG.

Conclusions

Analysis of gut microbiota characteristics in patients of different ages could ultimately contribute to the development of novel avenues for the treatment of HCC at different ages.

Changes of Intestinal Microflora in Colorectal Cancer Patients after Surgical Resection and Chemotherapy

OBJECTIVE

The change of bacterial flora structure in colorectal cancer (CRC) patients after treatment is not clear. The aim of this study was to explore the change and function of intestinal microflora in CRC before and after treatment.

METHOD

The 16S conserved region V3+V4 of intestinal flora obtained from CRC patients was sequenced and analyzed. Alpha and beta diversity indices were used to analyze the abundance and structure of gut flora. FAPROTAX, BugBase, and Tax4Fun software were used to analyze the species phenotypes and Kyoto Encyclopedia of Genes and Genomes Ontology (KO) function pathways.

RESULTS

Total abundance and structure of species in CRC patients were significantly increased compared with healthy people (control group) (P < 0.05), but there was no significant difference between CRC patients before and after treatment (P > 0.05). There was significant difference in relative abundance of bacteria at different levels (phylum, class, order, family, genus, and species) between the CRC group with after operation (CRC_O group) and chemotherapy (CRC_C group) treatment, particularly Prevotellaceae_UCG-001, Akkermansia, Fusicatenibacter, Tyzzerella_4, Megamonas, etc. in genus level. The KO function analysis showed that most of the bacteria with differences were mainly involved in the biosynthesis of lipopolysaccharide (Megamonas, Megasphaera, and Ruminococcus torques_group), protein digestion and absorption, renin-angiotensin system pathway (Akkermansia, Eubacterium_ruminantium_group, and Eubacterium_nodatum_group genus), adipocytokine signaling pathway and peroxisome pathway (Tyzzerella_4, Phascolarctobacterium, Ruminococcus_gnavus_group), and so on.

CONCLUSION

The abundance of intestinal microflora in CRC patients was increased significantly contrasted to healthy people, and surgery and chemotherapy were hard to reduce this phenomenon. Megamonas was involved in lipopolysaccharide biosynthesis and carcinogenesis in colorectal cancer. Surgery and drug treatment did not reduced lipopolysaccharide biosynthesis but increased the number of probiotic Akkermansia population and reduced the pathogenic bacteria Tyzzerella_4, participate in adipocytokine signaling pathway, and affect metabolism.

A comprehensive analysis of the microbiota composition and host driver gene mutations in colorectal cancer

Studies of both, microbiota and target therapy associated with gene mutations in colorectal cancer, (CRC) have attracted increasing attention. However, only a few of them analyzed the combined effects on CRC. we analyzed differences in intestinal microbiota of 44 colorectal cancer patients and 20 healthy controls (HC) using 16S rRNA gene sequencing of fecal samples. For 39 of the CRC patients, targeted Next Generation Sequencing (NGS) was carried out at formalin fixed paraffin embedded (FFPE) samples to identify somatic mutation profiles. Compared to the HC group, the microbial diversity of CRC patients was significantly lower. In the CRC group, we found a microbiome that was significantly enriched for strains of Bifidobacterium, Bacteroides, and Megasphaera whereas in the HC group the abundance of Collinsella, Faecalibacterium, and Agathobacter strains was higher. Among the mutations detected in the CRC group, the APC gene had the highest mutation rate (77%, 30/39). We found that the KRAS mutant type was closely associated with Faecalibacterium, Roseburia, Megamonas, Lachnoclostridium, and Harryflintia. Notably, Spearman correlation analysis showed that KRAS mutations were negatively correlated with the existence of Bifidobacterium and positively correlated with Faecalibacterium. By employing 16S rRNA gene sequencing, we identified more unique features of microbiota profiles in CRC patients. For the first time, our study showed that gene mutations could directly be linked to the microbiota composition of CRC patients. We hypothesize that the effect of a targeted colorectal cancer therapy is also closely related to the colorectal flora, however, this requires further investigation.

Therapeutic methods of gut microbiota modification in colorectal cancer management - fecal microbiota transplantation, prebiotics, probiotics, and synbiotics

The link between gut microbiota and the development of colorectal cancer has been investigated. An imbalance in the gut microbiota promotes the progress of colorectal carcinogenesis via multiple mechanisms, including inflammation, activation of carcinogens, and tumorigenic pathways as well as damaging host DNA. Several therapeutic methods are available with which to alter the composition and the activity of gut microbiota, such as administration of prebiotics, probiotics, and synbiotics; these can confer various benefits for colorectal cancer patients. Nowadays, fecal microbiota transplantation is the most modern way of modulating the gut microbiota. Even though data regarding fecal microbiota transplantation in colorectal cancer patients are still rather limited, it has been approved as a clinical method of treatment-recurrent Clostridium difficile infection, which may also occur in these patients. The major benefits of fecal microbiota transplantation include modulation of immunotherapy efficacy, amelioration of bile acid metabolism, and restoration of intestinal microbial diversity. Nonetheless, more studies are needed to assess the long-term effects of fecal microbiota transplantation. In this review, the impact of gut microbiota on the efficiency of anti-cancer therapy and colorectal cancer patients' overall survival is also discussed.

Intestinal Microbiota in Colorectal Cancer Surgery

The intestinal microbiota consists of numerous microbial species that collectively interact with the host, playing a crucial role in health and disease. Colorectal cancer is well-known to be related to dysbiotic alterations in intestinal microbiota. It is evident that the microbiota is significantly affected by colorectal surgery in combination with the various perioperative interventions, mainly mechanical bowel preparation and antibiotic prophylaxis. The altered postoperative composition of intestinal microbiota could lead to an enhanced virulence, proliferation of pathogens, and diminishment of beneficial microorganisms resulting in severe complications including anastomotic leakage and surgical site infections. Moreover, the intestinal microbiota could be utilized as a possible biomarker in predicting long-term outcomes after surgical CRC treatment. Understanding the underlying mechanisms of these interactions will further support the establishment of genomic mapping of intestinal microbiota in the management of patients undergoing CRC surgery.

Effects of PrObiotics on the Symptoms and Surgical ouTComes after Anterior REsection of Colon Cancer (POSTCARE): A Randomized, Double-Blind, Placebo-Controlled Trial

We investigated microbiota changes following surgical colon cancer resection and evaluate effects of probiotics on microbiota and surgical recovery. This randomized double-blind trial was performed at four medical centers in South Korea. Of 68 patients expected to undergo anterior sigmoid colon cancer resection, 60 were eligible, of whom 29 and 31 received probiotics and placebo, respectively, for four weeks, starting at one week preoperatively. Third- and/or fourth-week information on anterior resection syndrome (ARS), inflammatory markers, and quality of life was obtained. Stool sample analysis was conducted after randomization and bowel preparation and at three and four postoperative weeks. Bacteria were categorized into Set I (with probiotic effects) and II (colon cancer-associated). The probiotic group’s ARS score showed an improving trend (p = 0.063), particularly for flatus control (p = 0.030). Serum zonulin levels significantly decreased with probiotics. Probiotic ingestion resulted in compositional changes in gut microbiota; greater increases and decreases in Set I and II bacteria, respectively, occurred with probiotics. Compositional increase in Set I bacteria was associated with reduced white blood cells, neutrophils, neutrophil-lymphocyte ratio, and zonulin. Bifidobacterium composition was negatively correlated with zonulin levels in the probiotic group. Probiotics improved postoperative flatus control and modified postoperative changes in microbiota and inflammatory markers.

The effect of curative resection on fecal microbiota in patients with colorectal cancer: a prospective pilot study

Purpose

Although many studies have evaluated the association between intestinal microorganisms and the risk of colorectal cancer (CRC), only a few studies have investigated the changes in microorganisms following curative treatment for CRC. The current study analyzed changes in intestinal microbiota following curative surgery in CRC patients.

Methods

Stool samples were collected before and 6 months after surgery, from 11 patients with clinical stage III CRC, who underwent curative surgery between May 2017 and June 2017. Next, 16S rRNA gene sequencing was performed. Operational taxonomic units (OTUs) and alpha diversity were evaluated using the Shannon index. The bacterial compositions of the stools were analyzed according to taxonomic rank at genus and phylum levels.

Results

OTUs and alpha diversity were significantly decreased following surgery (P < 0.001 and P = 0.019, respectively). The compositions of several bacterial taxa changed after surgery. At genus level, proportions of pathogens such as Campylobacter, Fusobacterium, Haemophilus, Porphyromonas, and Prevotella, decreased after surgery (adjusted P < 0.05). At phylum level, the proportion of Fusobacteria decreased after surgery (adjusted P < 0.001).

Conclusion

Significant changes in intestinal microbial communities were noted following curative resection of CRC patients. Especially, decreases in pathogenic bacterial populations, such as Fusobacterium and Prevotella, which are known to be associated with CRC development, were detected even though OTUs and alpha diversity were decreased following curative resection. To determine and validate the clinical significance of these findings, large scale, prospective studies that include cancer prognoses are required.

Gut Microbiota-Based Algorithms in the Prediction of Metachronous Adenoma in Colorectal Cancer Patients Following Surgery

Evaluating the risk of colorectal metachronous adenoma (MA), which is a precancerous lesion, is necessary for metachronous colorectal cancer (CRC) precaution among CRC patients who had underwent surgical removal of their primary tumor. Here, discovery cohort (n = 41) and validation cohort (n = 45) of CRC patients were prospectively enrolled in this study. Mucosal and fecal samples were used for gut microbiota analysis by sequencing the 16S rRNA genes. Significant reduction of microbial diversity was noted in MA (P < 0.001). A signature defined by decreased abundance of eight genera and increased abundance of two genera strongly correlated with MA. The microbiota-based random forest (RF) model, established utilizing Escherichia–Shigella, Acinetobacter together with BMI in combination, achieved AUC values of 0.885 and 0.832 for MA, predicting in discovery and validation cohort, respectively. The RF model was performed as well for fecal and tumor adjacent mucosal samples with an AUC of 0.835 and 0.889, respectively. Gut microbiota profile of MA still existed in post-operative cohort patients, but the RF model could not be performed well on this cohort, with an AUC of 0.61. Finally, we introduced a risk score based on Escherichia–Shigella, Acinetobacter and BMI, and synchronous-adenoma achieved AUC values of 0.94 and 0.835 in discovery and validation cohort, respectively. This study presented a comprehensive landscape of gut microbiota in MA, demonstrated that the gut microbiota-based models and scoring system achieved good ability to predict the risk for developing MA after surgical resection. Our study suggests that gut microbiota is a potential predictive biomarker for MA.

Microbiota-Immune Interaction in the Pathogenesis of Gut-Derived Infection

Gut-derived infection is among the most common complications in patients who underwent severe trauma, serious burn, major surgery, hemorrhagic shock or severe acute pancreatitis (SAP). It could cause sepsis and multiple organ dysfunction syndrome (MODS), which are regarded as a leading cause of mortality in these cases. Gut-derived infection is commonly caused by pathological translocation of intestinal bacteria or endotoxins, resulting from the dysfunction of the gut barrier. In the last decades, the studies regarding to the pathogenesis of gut-derived infection mainly focused on the breakdown of intestinal epithelial tight junction and increased permeability. Limited information is available on the roles of intestinal microbial barrier in the development of gut-derived infection. Recently, advances of next-generation DNA sequencing techniques and its utilization has revolutionized the gut microecology, leading to novel views into the composition of the intestinal microbiota and its connections with multiple diseases. Here, we reviewed the recent progress in the research field of intestinal barrier disruption and gut-derived infection, mainly through the perspectives of the dysbiosis of intestinal microbiota and its interaction with intestinal mucosal immune cells. This review presents novel insights into how the gut microbiota collaborates with mucosal immune cells to involve the development of pathological bacterial translocation. The data might have important implication to better understand the mechanism underlying pathological bacterial translocation, contributing us to develop new strategies for prevention and treatment of gut-derived sepsis.