The Intestinal Microbiota in Colorectal Cancer

Synergistic effect of sodium butyrate and oxaliplatin on colorectal cancer

BACKGROUND

Oxaliplatin (OXA) is a chemotherapy agent commonly used in the treatment of colorectal cancer (CRC). Sodium butyrate (NaB) has an antitumor effect.

METHODS

In total, 30 patients in stage III who completed 8 cycles of chemotherapy regimens were recruited for this study. The patients were divided into good and bad groups based on the chemotherapy efficacy. Gas chromatography-mass spectrometry (GC/MS) was used to detect microbial metabolites in stool samples from CRC patients. Cell counting kit-8 (CCK-8), Annexin-V APC/7-AAD double staining, Transwell assays, scratch-wound assays, and EdU assays were used to detect cell proliferation, apoptosis, invasion and migration, respectively. Fluoroelectron microscopy was used to observe the cell structures. To verify the inhibitory effect of NaB and OXA at animal level, a subcutaneous transplanted tumor model was established. Finally, 16S sequencing technology was used to detect intestinal bacteria. GC-MS was used to detect metabolites in mouse stools.

RESULTS

NaB was a differential metabolite that affected the efficacy of OXA. NAB and oxaliplatin can synergically inhibit cell proliferation, migration and invasion, and induce cell apoptosis. Animal experiments confirmed the inhibitory effect of oxaliplatin and sodium butyrate on tumor in mice. In addition, the intestinal microbe detection and microbial metabolite detection in fecal samples from mice showed significant differences between butyrate-producing bacteria and NaB.

CONCLUSION

NaB and OXA can synergistically inhibit the proliferation, invasion and metastasis of CRC cells and promote the apoptosis of CRC cells. NaB, as an OXA synergist, has the potential to become a new clinical adjuvant in CRC chemotherapy.

ACSL4 is essential for radiation-induced intestinal injury by initiating ferroptosis

Lipid peroxidation-induced ferroptosis is a newly recognized type of programmed cell death. With the method of RNA sequencing, we found that irradiation (IR) markedly increased the expression of ferroptosis promotive genes, whereas reduced the expression of ferroptosis suppressive genes in murine intestine tissues, when compared with those of liver and lung tissues. By using ferroptosis inducer RSL-3 and inhibitor liproxstatin-1, we found that ferroptosis is essential for IR-induced intestinal injury. Acyl-CoA Synthetase Long-Chain Family Member 4 (ACSL4) is an important component for ferroptosis execution, and we found that ACSL4 expression was significantly upregulated in irradiated intestine tissues, but not in liver or lung tissues. Antibacterial and antifungal regents reduced the expression of ASCL4 and protected against tissue injury in irradiated intestine tissues. Further studies showed that troglitazone, a ACSL4 inhibitor, succeeded to suppresses intestine lipid peroxidation and tissue damage after IR.

Short- and Long-Term Effects of Different Antibiotics on the Gut Microbiota and Cytokines Level in Mice

BACKGROUND

Antibiotics are the first line of treatment for infectious diseases. However, their overuse can increase the spread of drug-resistant bacteria. The present study analyzed the impact of different types of antibiotics on the gut microbiome and cytokines level of mice.

METHODS

A total of five groups of 8-week-old male BALB/c mice (n = 35) were treated with piperacillin-tazobactam (TZP), ceftriaxone (CRO), tigecycline (TGC), levofloxacin (LEV) or normal saline (Ctrl), respectively, for up to 4 weeks. Fecal samples were analyzed by bacterial 16S rRNA gene sequencing for bacterial identification. Blood samples were used for the determination of 23 serum cytokines using multiplex immunoassay.

RESULTS

Exposure to antibiotics was shown to affect the normal weight gain of mice. Significant changes in gut composition caused by TZP, CRO and TGC treatment included the decreased abundance of Bacteroidetes (p < 0.01), Muribaculaceae (p < 0.01) and Lachnospiraceae (p < 0.01), and the increased abundance of Proteobacteria (p < 0.05), Enterobacteriaceae (including Klebsiella and Enterobacter) (p < 0.01) and Enterococcaceae (including Enterococcus) (p < 0.01). After 4-week treatment, the TZP, CRO and LEV groups had significantly lower concentrations of several serum cytokines. Correlation analysis of the top 30 bacterial genera and cytokines showed that Enterococcus and Klebsiella were strongly positively correlated with tumor necrosis factor-α (TNF-α), interleukins (IL) IL-12p70 and IL-1β. Desulfovibrio, Candidatus Saccharimonas, norank_f__norank_o__Clostridia_UCG-014, Lactobacillus, and Roseburia were strongly negatively correlated with these cytokines.

CONCLUSION

This study demonstrates the effects of various antibiotics on the intestinal microflora and immune status of mice. Compared with TZP, CRO and TGC, LEV had minimal impact on the gut microbiota. In addition to TGC, long-term TZP, CRO and LEV intervention can lead to a decrease in serum cytokine levels, which may depend on the intestinal microflora, antibiotic used and the duration of treatment.

Antibiotic ampicillin induces immune tolerance in renal transplantation by regulating the proportion of intestinal flora in mice

Objectives

There are significant differences in the composition of intestinal flora in renal transplant recipients before and after an operation, which has a great impact on the prognosis of renal transplantation. The purpose of this project is to study the effect of intestinal flora imbalance on renal transplantation.

Methods

The animal model of renal transplantation was established after intestinal flora imbalance (mice pretreated with compound antibiotics), or the animal model of renal transplantation was established after being pretreated with single antibiotics. HE, PAS, and Masson staining was used to detecting the histopathological changes of transplanted renal. The expression of inflammatory factors and infiltration of inflammatory cells of renal tissue were respectively been detected by ELISA kit and flow cytometry.

Results

Antibiotic pretreatment restored weight loss, and decreased serum creatinine level in mice after renal transplantation. The tissue staining, ELISA assay, and flow cytometry data showed that antibiotic pretreatment alleviated injury of the renal allograft, inhibited the inflammatory factors levels, and reduced inflammatory cell infiltration in mice after renal transplantation. Furthermore, single antibiotic, especially ampicillin pretreatment can also play the same role as compound antibiotics, such as restoring weight loss, decreasing serum creatinine level, alleviating renal allograft injury, inhibiting inflammatory factors levels, and reducing inflammatory cell infiltration in mice after renal transplantation.

Conclusions

Antibiotic ampicillin may inhibit inflammatory cell infiltration after renal transplantation by regulating the proportion of intestinal flora in mice, to reduce renal injury and play a role in renal protection.

Assessment of the Gut Microbiota during Juice Fasting with and without Inulin Supplementation: A Feasibility Study in Healthy Volunteers

Prebiotic inulin consumption provides health benefits to the host and has also been associated with a reduction in hunger cravings. We conducted a pilot crossover study to investigate the feasibility of a juice fasting intervention with and without inulin supplementation. We also examined trends of how the microbial community in the human gut adapts to juice fasting as well as to inulin intake during juice fasting. Six healthy volunteers were fasting for three consecutive days consuming a total of 300 kcal daily provided by vegetable juices, framed by two days with a total daily calorie intake of 800 kcal, respectively. During one fasting period, participants consumed additionally 24 g of inulin daily. Stool samples were collected for the analysis of the microbial composition using 16S rRNA gene sequencing. Although no significant uniform changes were observed on the microbiome, quantitative changes in the microbial composition suggest a stronger decrease in alpha-diversity after fasting compared to the fasting intervention with additional inulin intake. The intake of inulin did not affect compliance for the fasting intervention but appeared to increase relative abundance of Bifidobacteria in participants who tolerated it well. Further studies with a larger sample size to overcome inter-individual microbiota differences are warranted to verify our observations.

Fusobacterium nucleatum stimulates cell proliferation and promotes PD-L1 expression via IFIT1-related signal in colorectal cancer

Fusobacterium nucleatum (F. nucleatum) is enriched in colorectal cancer (CRC) tissues and a high amount of F. nucleatum was associated with an immunosuppressive tumor environment. PD-L1 is an important immune checkpoint expressed on tumor cells and promotes tumor immune escape. Whether PD-L1 is regulated by F. nucleatum is still unclear. We demonstrated that F. nucleatum promoted CRC progression and upregulated PD-L1 protein expression in CRC cell lines. Combined m⁶A-seq and RNA-seq identified m⁶A-modified IFIT1 mediating F. nucleatum induced PD-L1 upregulation. IFIT1 mRNA was modified with m⁶A modifications in 3'UTR and the m⁶A levels were altered by F. nucleatum treatment. Our results also indicated that IFIT1 served as a potential oncogene in CRC and regulated PD-L1 protein levels through altering PD-L1 ubiquitination. Clinical CRC data confirmed the correlation among F. nucleatum abundance, IFIT1 and PD-L1 expressions. Our work highlighted the function of F. nucleatum in stimulating PD-L1 expression through m⁶A-modified IFIT1 and provided new aspects for understanding F. nucleatum mediated immune escape.

Effects of gut microbiota on immune responses and immunotherapy in colorectal cancer

Accumulating evidence suggests that gut microbial dysbiosis is implicated in colorectal cancer (CRC) initiation and progression through interaction with host immune system. Given the intimate relationship between the gut microbiota and the antitumor immune responses, the microbiota has proven to be effective targets in modulating immunotherapy responses of preclinical CRC models. However, the proposed putative mechanisms of how these bacteria affect immune responses and immunotherapy efficacy remains obscure. In this review, we summarize recent findings of clinical gut microbial dysbiosis in CRC patients, the reciprocal interactions between gut microbiota and the innate and/or the adaptive immune system, as well as the effect of gut microbiota on immunotherapy response in CRC. Increased understanding of the gut microbiota-immune system interactions will benefit the rational application of microbiota to the clinical promising biomarker or therapeutic strategy as a cancer immunotherapy adjuvant.

Compartmentalization of the host microbiome: how tumor microbiota shapes checkpoint immunotherapy outcome and offers therapeutic prospects

The host microbiome is polymorphic, compartmentalized, and composed of distinctive tissue microbiomes. While research in the field of cancer immunotherapy has provided an improved understanding of the interaction with the gastrointestinal microbiome, the significance of the tumor-associated microbiome has only recently been grasped. This article provides a state-of-the-art review about the tumor-associated microbiome and sheds light on how local tumor microbiota shapes anticancer immunity and influences checkpoint immunotherapy outcome. The direct route of interaction between cancer cells, immune cells, and microbiota in the tumor microenvironment is emphasized and advocates a focus on the tumor-associated microbiome in addition to the spatially separated gut compartment. Since the mechanisms underlying checkpoint immunotherapy modulation by tumor-associated microbiota remain largely elusive, future research should dissect the pathways involved and outline strategies to therapeutically modulate microbes and their products within the tumor microenvironment. A more detailed knowledge about the mechanisms governing the composition and functional quality of the tumor microbiome will improve cancer immunotherapy and advance precision medicine for solid tumors.

Microbe-based therapies for colorectal cancer: Advantages and limitations

Cancer is one of the leading global causes of death in both men and women. Colorectal cancer (CRC) alone accounts for ∼10 % of total new global cases and poses an over 4% lifetime risk of developing cancer. Recent advancements in the field of biotechnology and microbiology concocted novel microbe-based therapies to treat various cancers, including CRC. Microbes have been explored for human use since centuries, especially for the treatment of various ailments. The utility of microbes in cancer therapeutics is widely explored, and various bacteria, fungi, and viruses are currently in use for the development of cancer therapeutics. The human gut hosts about 100 trillion microbes that release their metabolites in active, inactive, or dead conditions. Microbial secondary metabolites, proteins, immunotoxins, and enzymes are used to target cancer cells to induce cell cycle arrest, apoptosis, and death. Various approaches, such as dietary interventions, the use of prebiotics and probiotics, and fecal microbiota transplantation have been used to modulate the gut microbiota in order to prevent or treat CRC pathogenesis. The present review highlights the role of the gut microbiota in CRC precipitation, the potential mechanisms and use of microorganisms as CRC biomarkers, and strategies to modulate microbiota for the prevention and treatment of CRC.

A Screening of Native (Poly)phenols and Gut-Related Metabolites on 3D HCT116 Spheroids Reveals Gut Health Benefits of a Flavan-3-ol Metabolite

SCOPE

Epidemiological evidence suggests that a reduced risk of colorectal cancer (CRC) is correlated with high consumption of fruits and vegetables, which are major sources of fiber and phytochemicals, such as flavan-3-ols. However, it remains unknown how these phytochemicals and their specific gut-related metabolites may alter cancer cell behavior.

METHODS AND RESULTS

A focused screening using native (poly)phenols and gut microbial metabolites (GMMs) on 3D HCT116 spheroids is carried out using a high-throughput imaging approach. Dose-responses, IC50 , and long-term exposure are calculated for the most promising native (poly)phenols and GMMs. As a result, this research shows that (poly)phenol catabolites may play a key role in preventing cancer propagation. Indeed, µM concentration levels of (4R)-5-(3',4'-dihydroxyphenyl)-γ-valerolactone significantly decrease spheroid size at early stages of spheroid aggregation and gene expression of matrix metalloproteinases.

CONCLUSION

A chronic exposure to (4R)-5-(3',4'-dihydroxyphenyl)-γ-valerolactone may lead to a reduced CRC risk. Daily intake of monomeric, oligomeric, and polymeric flavan-3-ols may increase the colonic concentrations of this metabolite, and, in turn, this compound may act locally interacting with intestinal epithelial cells, precancerous and cancer cells.

Commensal microbiota from patients with inflammatory bowel disease produce genotoxic metabolites

Microbiota-derived metabolites that elicit DNA damage can contribute to colorectal cancer (CRC). However, the full spectrum of genotoxic chemicals produced by indigenous gut microbes remains to be defined. We established a pipeline to systematically evaluate the genotoxicity of an extensive collection of gut commensals from inflammatory bowel disease patients. We identified isolates from divergent phylogenies whose metabolites caused DNA damage and discovered a distinctive family of genotoxins-termed the indolimines-produced by the CRC-associated species Morganella morganii. A non-indolimine-producing M. morganii mutant lacked genotoxicity and failed to exacerbate colon tumorigenesis in mice. These studies reveal the existence of a previously unexplored universe of genotoxic small molecules from the microbiome that may affect host biology in homeostasis and disease.

Antitumor effects of polysaccharides from Tetrastigma hemsleyanum Diels et Gilg via regulation of intestinal flora and enhancing immunomodulatory effects in vivo

Tetrastigma hemsleyanum Diels et Gilg is a traditional Chinese herbal medicine with high medicinal value, and antitumor, antioxidant and anti-inflammatory biological activities. However, while several studies have focused on flavonoids in Tetrastigma hemsleyanum tubers, there are few studies on the enhanced immune effect of Tetrastigma hemsleyanum polysaccharides (THP). In this study, we evaluated the antitumor effect of THP in a lung tumor model and explored the mechanism of antitumor activity through intestinal flora. In addition, a cyclophosphamide (CTX)-induced immunosuppression model was used to declare the immunomodulatory effect of THP in the immunosuppressive state induced by antitumor drugs. The results showed that THP increased the content of ileum secreted immunoglobulin A (SIgA) and cecum short-chain fatty acids (SCFAs) and improved microbial community diversity, regulating the relative abundance of dominant microbiota flora from the phylum level to the genus level, and recovering the intestinal microflora disorder caused by tumors. Additionally, THP can increase the organ indices and improve immune organ atrophy. THP can upregulate routine blood counts and stimulate the production of the serum cytokines. THP also promoted the macrophage phagocytic index, NK-cell activation, and complement and immunoglobulin (IgG, IgA, IgM) levels. The detection of Splenic lymphocyte proliferation and T lymphocyte subsets also sideways reflects that THP can restore CTX-induced immune inhibition in mice. In conclusion, this study suggests that THP can effectively achieve the enhanced antitumor effects, regulate gut microbiota and improve the immunosuppression induced by antitumor drugs. Therefore, THP can enhance the immune capacity and provide novel immunomodulatory and antineoplastic adjuvant agents.

Gut Microbiota and Therapy in Metastatic Melanoma: Focus on MAPK Pathway Inhibition

Gut microbiome (GM) and its either pro-tumorigenic or anti-tumorigenic role is intriguing and constitutes an evolving landscape in translational oncology. It has been suggested that these microorganisms may be involved in carcinogenesis, cancer treatment response and resistance, as well as predisposition to adverse effects. In melanoma patients, one of the most immunogenic cancers, immune checkpoint inhibitors (ICI) and MAPK-targeted therapy—BRAF/MEK inhibitors—have revolutionized prognosis, and the study of the microbiome as a modulating factor is thus appealing. Although BRAF/MEK inhibitors constitute one of the main backbones of treatment in melanoma, little is known about their impact on GM and how this might correlate with immune re-induction. On the contrary, ICI and their relationship to GM has become an interesting field of research due to the already-known impact of immunotherapy in modulating the immune system. Immune reprogramming in the tumor microenvironment has been established as one of the main targets of microbiome, since it can induce immunosuppressive phenotypes, promote inflammatory responses or conduct anti-tumor responses. As a result, ongoing clinical trials are evaluating the role of fecal microbiota transplant (FMT), as well as the impact of using dietary supplements, antibiotics and probiotics in the prediction of response to therapy. In this review, we provide an overview of GM’s link to cancer, its relationship with the immune system and how this may impact response to treatments in melanoma patients. We also discuss insights about novel therapeutic approaches including FMT, changes in diet and use of probiotics, prebiotics and symbiotics. Finally, we hypothesize on the possible pathways through which GM may impact anti-tumor efficacy in melanoma patients treated with targeted therapy, an appealing subject of which little is known.

Immunotherapy-based novel nanoparticles in the treatment of gastrointestinal cancer: Trends and challenges

Gastrointestinal cancer (GIC) is the most common cancer with a poor prognosis. Currently, surgery is the main treatment for GIC. However, the high rate of postoperative recurrence leads to a low five-year survival rate. In recent years, immunotherapy has received much attention. As the only immunotherapy drugs approved by the Food and Drug Administration (FDA), immune checkpoint blockade (ICB) drugs have great potential in cancer therapy. Nevertheless, the efficacy of ICB treatment is greatly limited by the low immunogenicity and immunosuppressive microenvironment of GIC. Therefore, the targets of immunotherapy have expanded from ICB to increasing tumor immunogenicity, increasing the recruitment and maturation of immune cells and reducing the proportion of inhibitory immune cells, such as M2-like macrophages, regulatory T cells and myeloid-derived suppressor cells. Moreover, with the development of nanotechnology, a variety of nanoparticles have been approved by the FDA for clinical therapy, so novel nanodrug delivery systems have become a research focus for anticancer therapy. In this review, we summarize recent advances in the application of immunotherapy-based nanoparticles in GICs, such as gastric cancer, hepatocellular carcinoma, colorectal cancer and pancreatic cancer, and described the existing challenges and future trends.

Terbinafine prevents colorectal cancer growth by inducing dNTP starvation and reducing immune suppression

Existing evidence indicates that gut fungal dysbiosis might play a key role in the pathogenesis of colorectal cancer (CRC). We sought to explore whether reversing the fungal dysbiosis by terbinafine, an approved antifungal drug, might inhibit the development of CRC. A population-based study from Sweden identified a total of 185 patients who received terbinafine after their CRC diagnosis and found that they had a decreased risk of death (hazard ratio = 0.50) and metastasis (hazard ratio = 0.44) compared with patients without terbinafine administration. In multiple mouse models of CRC, administration of terbinafine decreased the fungal load, the fungus-induced myeloid-derived suppressor cell (MDSC) expansion, and the tumor burden. Fecal microbiota transplantation from mice without terbinafine treatment reversed MDSC infiltration and partially restored tumor proliferation. Mechanistically, terbinafine directly impaired tumor cell proliferation by reducing the ratio of nicotinamide adenine dinucleotide phosphate (NADP+) to reduced form of nicotinamide adenine dinucleotide phosphate (NADPH), suppressing the activity of glucose-6-phosphate dehydrogenase (G6PD), resulting in nucleotide synthesis disruption, deoxyribonucleotide (dNTP) starvation, and cell-cycle arrest. Collectively, terbinafine can inhibit CRC by reversing fungal dysbiosis, suppressing tumor cell proliferation, inhibiting fungus-induced MDSC infiltration, and restoring antitumor immune response.

Western-Style Diet, pks Island-Carrying Escherichia coli, and Colorectal Cancer: Analyses From Two Large Prospective Cohort Studies

BACKGROUND & AIMS

Evidence supports a carcinogenic role of Escherichia coli carrying the pks island that encodes enzymes for colibactin biosynthesis. We hypothesized that the association of the Western-style diet (rich in red and processed meat) with colorectal cancer incidence might be stronger for tumors containing higher amounts of pks+E coli.

METHODS

Western diet score was calculated using food frequency questionnaire data obtained every 4 years during follow-up of 134,775 participants in 2 United States-wide prospective cohort studies. Using quantitative polymerase chain reaction, we measured pks+E coli DNA in 1175 tumors among 3200 incident colorectal cancer cases that had occurred during the follow-up. We used the 3200 cases and inverse probability weighting (to adjust for selection bias due to tissue availability), integrated in multivariable-adjusted duplication-method Cox proportional hazards regression analyses.

RESULTS

The association of the Western diet score with colorectal cancer incidence was stronger for tumors containing higher levels of pks+E coli (Pheterogeneity = .014). Multivariable-adjusted hazard ratios (with 95% confidence interval) for the highest (vs lowest) tertile of the Western diet score were 3.45 (1.53-7.78) (Ptrend = 0.001) for pks+E coli-high tumors, 1.22 (0.57-2.63) for pks+E coli-low tumors, and 1.10 (0.85-1.42) for pks+E coli-negative tumors. The pks+E coli level was associated with lower disease stage but not with tumor location, microsatellite instability, or BRAF, KRAS, or PIK3CA mutations.

CONCLUSIONS

The Western-style diet is associated with a higher incidence of colorectal cancer containing abundant pks+E coli, supporting a potential link between diet, the intestinal microbiota, and colorectal carcinogenesis.

Portulaca oleracea extract reduces gut microbiota imbalance and inhibits colorectal cancer progression via inactivation of the Wnt/β-catenin signaling pathway

BACKGROUND

Portulaca oleracea is a known medicinal plant with antioxidant, anti-inflammatory, and anticancer activities, and it may also function an important role in colorectal cancer (CRC).

PURPOSE

We probed into study the critical function of Portulaca oleracea extract (POE) in CRC and the related downstream factors.

METHODS

Azoxymethane (AOM) and dextransodiumsulfate (DSS) were used to induce mouse models of CRC, which were then administered different doses of POE to evaluate the therapeutic effects of POE on CRC. Diversity, abundance, and function of gut microbiota were analyzed. Moreover, the potential molecular targets of POE inhibiting CRC development were determined. Expression of c-Myc and cyclin D1 as well as CRC cell proliferation and apoptosis was detected.

RESULTS

POE treatment inhibited AOM/DSS-induced CRC development in mice and ameliorated gut microbial imbalance. Bioinformatic analysis revealed marked differences in the gut microbiota between CRC samples and normal samples and that 20 differential microbiota may be involved in CRC development through the Wnt signaling pathway. Additionally, c-Myc and cyclin D1 were identified to be the key downstream target genes of the Wnt/β-catenin signaling pathway. In vitro data revealed that POE played a suppressive role in the proliferation of CRC cells by reducing the expression of c-Myc and cyclin D1 and inactivating the Wnt/β-catenin signaling pathway.

CONCLUSION

This study underlines that POE reduces gut microbiota imbalance and inhibits CRC development and progression via inactivation of the Wnt/β-catenin signaling pathway and downregulation of c-Myc and cyclin D1 expression, which is expected to be a potential biomarker for CRC.

Rectal Cancer Presenting with Absceding Infection Due to Fusobacterium nucleatum

Intestinal microbiota such as Fusobacterium nucleatum play an important role in the pathogenesis of colorectal cancer. Here, we describe the case of a 47-year-old patient presenting with endophthalmitis and a liver abscess due to Fusobacterium nucleatum that prompted the diagnosis of colorectal cancer as the most likely source of infection. This case highlights that colorectal cancer needs to be considered in patients with systemic infection with Fusobacterium nucleatum and colonoscopy should be performed.

Cholecystectomy promotes the development of colorectal cancer by the alternation of bile acid metabolism and the gut microbiota

The incidence and mortality of colorectal cancer (CRC) have been markedly increasing worldwide, causing a tremendous burden to the healthcare system. Therefore, it is crucial to investigate the risk factors and pathogenesis of CRC. Cholecystectomy is a gold standard procedure for treating symptomatic cholelithiasis and gallstone diseases. The rhythm of bile acids entering the intestine is altered after cholecystectomy, which leads to metabolic disorders. Nonetheless, emerging evidence suggests that cholecystectomy might be associated with the development of CRC. It has been reported that alterations in bile acid metabolism and gut microbiota are the two main reasons. However, the potential mechanisms still need to be elucidated. In this review, we mainly discussed how bile acid metabolism, gut microbiota, and the interaction between the two factors influence the development of CRC. Subsequently, we summarized the underlying mechanisms of the alterations in bile acid metabolism after cholecystectomy including cellular level, molecular level, and signaling pathways. The potential mechanisms of the alterations on gut microbiota contain an imbalance of bile acid metabolism, cellular immune abnormality, acid-base imbalance, activation of cancer-related pathways, and induction of toxin, inflammation, and oxidative stress.

Characteristics of the Gut Bacterial Composition in People of Different Nationalities and Religions

High-throughput sequencing has made it possible to extensively study the human gut microbiota. The links between the human gut microbiome and ethnicity, religion, and race remain rather poorly understood. In this review, data on the relationship between gut microbiota composition and the nationality of people and their religion were generalized. The unique gut microbiome of a healthy European (including Slavic nationality) is characterized by the dominance of the phyla Firmicutes, Bacteroidota, Actinobacteria, Proteobacteria, Fusobacteria, and Verrucomicrobia. Among the African population, the typical members of the microbiota are Bacteroides and Prevotella. The gut microbiome of Asians is very diverse and rich in members of the genera Prevotella, Bacteroides Lactobacillus, Faecalibacterium, Ruminococcus, Subdoligranulum, Coprococcus, Collinsella, Megasphaera, Bifidobacterium, and Phascolarctobacterium. Among Buddhists and Muslims, the Prevotella enterotype is characteristic of the gut microbiome, while other representatives of religions, including Christians, have the Bacteroides enterotype. Most likely, the gut microbiota of people of different nationalities and religions are influenced by food preferences. The review also considers the influences of pathologies such as obesity, Crohn’s disease, cancer, diabetes, etc., on the bacterial composition of the guts of people of different nationalities.

Implication of gut microbiome in immunotherapy for colorectal cancer

Colorectal cancer (CRC) constitutes the third most frequently reported malignancy in the male population and the second most common in women in the last two decades. Colon carcinogenesis is a complex, multifactorial event, resulting from genetic and epigenetic aberrations, the impact of environmental factors, as well as the disturbance of the gut microbial ecosystem. The relationship between the intestinal microbiome and carcinogenesis was relatively undervalued in the last decade. However, its remarkable effect on metabolic and immune functions on the host has been in the spotlight as of recent years. There is a strong relationship between gut microbiome dysbiosis, bowel pathogenicity and responsiveness to anti-cancer treatment; including immunotherapy. Modifications of bacteriome consistency are closely associated with the immunologic response to immunotherapeutic agents. This condition that implies the necessity of gut microbiome manipulation. Thus, creatingan optimal response for CRC patients to immunotherapeutic agents. In this paper, we will review the current literature observing how gut microbiota influence the response of immunotherapy on CRC patients.

Exploring the mechanism of action of Sanzi formula in intervening colorectal adenoma by targeting intestinal flora and intestinal metabolism

Background

Sanzi formula (SZF) is a kind of Chinese herbal compound that has a certain effect on the prevention and treatment of colorectal adenoma (CRA), which can prevent and control the process of CRA-cancer transformation. In this study, we explored the mechanism of action of SZF in anti-CRA using 16S rRNA sequencing and metabolomics technology.

Methods

Mice were randomly divided into three groups: Control group, Apc^min/+ model group, and SZF treatment group. Except for the Control group, which used C57BL/6 J mice, the remaining two groups used Apc^min/+ mice. The Control group and Apc^min/+ model group were treated with ultrapure water by gavage, while the SZF treatment group was treated with SZF for 12 weeks. During this period, the physical changes of mice in each group were observed. The gut microbiota was determined by high-throughput sequencing of the 16S rRNA gene, and LC-ESI-MS/MS was used for colorectal metabolomics analysis.

Results

Sequencing of the 16S rRNA gut flora yielded 10,256 operational taxonomic units and metabolomic analysis obtained a total of 366 differential metabolites. The intestinal flora analysis showed that SZF could improve intestinal flora disorders in Apc^min/+ mice. For instance, beneficial bacteria such as Gastranaerophilales significantly increased and harmful bacteria such as Angelakisella, Dubosiella, Muribaculum, and Erysipelotrichaceae UCG-003 substantially decreased after the SZF intervention. In addition, metabolomic data analysis demonstrated that SZF also improved the colorectal metabolic profile of Apc^min/+ mice. In Apc^min/+ mice, metabolites such as Anserine and Ectoine were typically increased after SZF intervention; in contrast, metabolites such as Taurocholic acid, Taurochenodesoxycholic acid, Hyocholic acid, Cholic acid, and Tauro-alpha-muricholic acid showed noteworthy reductions. Metabolic flora association analysis indicated that 13 differential flora and 11 differential metabolites were associated.

Conclusion

SZF affects the abundance of specific intestinal flora and regulates intestinal flora disorders, improves colorectal-specific metabolites, and ameliorates intestinal metabolic disorders to prevent and treat CRA. Furthermore, the application of intestinal flora and colorectal metabolomics association analysis offers new strategies to reveal the mechanism of action of herbal medicines for the treatment of intestinal diseases.

Bidirectional effects of intestinal microbiota and antibiotics: a new strategy for colorectal cancer treatment and prevention

PURPOSE

Colorectal cancer (CRC) is the third most common cancer worldwide, and its incidence and mortality rates are increasing every year. The intestinal microbiota has been called the "neglected organ" and there is growing evidence that the intestinal microbiota and its metabolites can be used in combination with immunotherapy, radiotherapy and chemotherapy to greatly enhance the treatment of colorectal cancer and to address some of the side effects and adverse effects of these therapies. Antibiotics have great potential to eliminate harmful microbiota, control infection, and reduce colorectal cancer side effects. However, the use of antibiotics has been a highly controversial issue, and numerous retrospective studies have shown that the use of antibiotics affects the effectiveness of treatment (especially immunotherapy). Understanding the bi-directional role of the gut microbiota and antibiotics will further enhance our research into the diagnosis and treatment of cancer.

METHODS

We searched the "PubMed" database and selected the following keywords "intestinal microbiota, antibiotics, treatment, prevention, colorectal cancer". In this review, we discuss the role of the intestinal microbiota in immunotherapy, radiotherapy, chemotherapy, diagnosis, and prevention of CRC. We also conclude that the intestinal microbiota and antibiotics work together to promote the treatment of CRC through a bidirectional effect.

RESULTS

We found that the intestinal microbiota plays a key role in promoting immunotherapy, chemotherapy, radiotherapy, diagnosis and prevention of CRC. In addition, gut microbiota and antibiotic interactions could be a new strategy for CRC treatment.

CONCLUSION

The bi-directional role of the intestinal microbiota and antibiotics plays a key role in the prevention, diagnosis, and treatment of colorectal cancer.

Complement downregulation promotes an inflammatory signature that renders colorectal cancer susceptible to immunotherapy

BACKGROUND AND AIMS

The role of inflammatory immune responses in colorectal cancer (CRC) development and response to therapy is a matter of intense debate. While inflammation is a known driver of CRC, inflammatory immune infiltrates are a positive prognostic factor in CRC and predispose to response to immune checkpoint blockade (ICB) therapy. Unfortunately, over 85% of CRC cases are primarily unresponsive to ICB due to the absence of an immune infiltrate, and even the cases that show an initial immune infiltration can become refractory to ICB. The identification of therapy supportive immune responses in the field has been partially hindered by the sparsity of suitable mouse models to recapitulate the human disease. In this study, we aimed to understand how the dysregulation of the complement anaphylatoxin C3a receptor (C3aR), observed in subsets of patients with CRC, affects the immune responses, the development of CRC, and response to ICB therapy.

METHODS

We use a comprehensive approach encompassing analysis of publicly available human CRC datasets, inflammation-driven and newly generated spontaneous mouse models of CRC, and multiplatform high-dimensional analysis of immune responses using microbiota sequencing, RNA sequencing, and mass cytometry.

RESULTS

We found that patients' regulation of the complement C3aR is associated with epigenetic modifications. Specifically, downregulation of C3ar1 in human CRC promotes a tumor microenvironment characterized by the accumulation of innate and adaptive immune cells that support antitumor immunity. In addition, in vivo studies in our newly generated mouse model revealed that the lack of C3a in the colon activates a microbiota-mediated proinflammatory program which promotes the development of tumors with an immune signature that renders them responsive to the ICB therapy.

CONCLUSIONS

Our findings reveal that C3aR may act as a previously unrecognized checkpoint to enhance antitumor immunity in CRC. C3aR can thus be exploited to overcome ICB resistance in a larger group of patients with CRC.

Lactate: A regulator of immune microenvironment and a clinical prognosis indicator in colorectal cancer

Lactate can play an immunosuppressive role in the tumor microenvironment and promote tumor development by recruiting and inducing the activity of immunosuppressive cells and molecules. High lactate concentrations are important for tumor cell metastasis, angiogenesis, and treatment resistance. With the in-depth studies on tumor metabolism, lactate, one of the key factors involved in glycolysis, has been increasing emerged its characteristic clinical value in colorectal cancer (CRC). In this study, lactate genes were screened based on lactate metabolism pathways. Subsequently, the lactate subtypes were determined by clustering and analysis of the subtypes at all levels, including immune checkpoints, immune infiltration, and clinical characteristics, which revealed the biological significance of lactate metabolism in CRC. Subtype-based differential gene analysis resulted in a lactate score, which stratifies the prognosis of CRC. We discovered that 27 lactate genes and 61 lactate-phenotype genes are associated with immune cell infiltration and have a significant prognostic efficacy. The CRC patients were clustered into four subtypes and five clusters, based on lactate genes and lactate-phenotype genes, respectively. There are significant differences in survival time and activities of hallmark pathways, namely immune-related signatures and chemokines, among these subtypes and clusters. Particularly, cluster 2 and subtype 1 have significantly higher lactate scores than that of the others. In conclusion, lactate score is an independent prognostic factor for cancer that can be used as a clinical guide for predicting CRC progression and as an evaluation factor for the effect of immunotherapy in CRC.

New insights into natural products that target the gut microbiota: Effects on the prevention and treatment of colorectal cancer

Colorectal cancer (CRC) is one of the most common malignant carcinomas. CRC is characterized by asymptomatic onset, and most patients are already in the middle and advanced stages of disease when they are diagnosed. Inflammatory bowel disease (IBD) and the inflammatory-cancer transformation of advanced colorectal adenoma are the main causes of CRC. There is an urgent need for effective prevention and intervention strategies for CRC. In recent years, rapid research progress has increased our understanding of gut microbiota. Meanwhile, with the deepening of research on the pathogenesis of colorectal cancer, gut microbiota has been confirmed to play a direct role in the occurrence and treatment of colorectal cancer. Strategies to regulate the gut microbiota have potential value for application in the prevention and treatment of CRC. Regulation of gut microbiota is one of the important ways for natural products to exert pharmacological effects, especially in the treatment of metabolic diseases and tumours. This review summarizes the role of gut microbiota in colorectal tumorigenesis and the mechanism by which natural products reduce tumorigenesis and improve therapeutic response. We point out that the regulation of gut microbiota by natural products may serve as a potential means of treatment and prevention of CRC.

Limosilactobacillus fermentum-fermented ginseng improved antibiotic-induced diarrhoea and the gut microbiota profiles of rats

AIMS

This study investigated the efficacy of Limosilactobacillus fermentum-fermented ginseng for improving colitis and the gut microbiota profiles in rats and explored the benefits of the L. fermentum fermentation process to ginseng.

METHODS AND RESULTS

Ginseng polysaccharide and ginsenoside from fermented ginseng were analysed by UV and HPLC. Antibiotic-fed rats were treated with fermented ginseng and a L. fermentum-ginseng mixture. Histopathology- and immune-related factors (TNF-α, IL-1β, IL-6 and IL-10) of the colon were assayed by using pathological sections and ELISA. After treatment, fermented ginseng relieved the symptoms of antibiotic-induced diarrhoea and colon inflammation, and the expression of colon immune factors returned to normal. The gut microbial communities were identified by 16S rRNA gene sequencing. The results showed that the alterations in the gut microbiota returned to normal. In addition, the gut microbiota changes were correlated with immune factor expression after treatment. The fermented ginseng had better biological functions than a L. fermentum-ginseng mixture.

CONCLUSIONS

Fermented ginseng can relieve diarrhoea and colon inflammation and restore the gut microbiota to its original state. The process of L. fermentum fermentation can expand the therapeutic use of ginseng.

SIGNIFICANCE AND IMPACT OF THE STUDY

This research suggested the potential function of fermented ginseng to relieve diarrhoea and recover the gut microbiota to a normal level and explored the benefits of the Limosilactobacillus fermentum fermentation process to ginseng.

Comprehensive analysis of triphenyl phosphate: An environmental explanation of colorectal cancer progression

Organophosphate flame retardants (OPFRs) are alternatives to brominated flame retardants (BFRs) and have recently gained wide acceptance in various materials. For the treatment and prevention of diseases, it is also important to clarify the relationship between OPFRs and tumors, despite the fact that OPFRs are less toxic than BFRs. This research used the TCGA and CTD databases for transcriptome profiling and identifying OPFRs-related genes. GO and KEGG analyses suggested that OPFRs may be closely related to colorectal cancer (CRC), and genes correlated with OPFRs were significantly and differently expressed between tumor and normal group. Further, OPFRs-related genes were associated with a good prognosis in CRC patients. The deeper research demonstrated that one of the OPFRs-triphenyl phosphate could significantly increased the viability and proliferation of CRC cell lines compared with the control group. In addition, Our research also found that melatonin at 50 μM could significantly impact CRC cell proliferation and migration ability induced by TPP.

Developing dietary interventions as therapy for cancer

Cancer cells acquire distinct metabolic preferences based on their tissue of origin, genetic alterations and degree of interaction with systemic hormones and metabolites. These adaptations support the increased nutrient demand required for increased growth and proliferation. Diet is the major source of nutrients for tumours, yet dietary interventions lack robust evidence and are rarely prescribed by clinicians for the treatment of cancer. Well-controlled diet studies in patients with cancer are rare, and existing studies have been limited by nonspecific enrolment criteria that inappropriately grouped together subjects with disparate tumour and host metabolic profiles. This imprecision may have masked the efficacy of the intervention for appropriate candidates. Here, we review the metabolic alterations and key vulnerabilities that occur across multiple types of cancer. We describe how these vulnerabilities could potentially be targeted using dietary therapies including energy or macronutrient restriction and intermittent fasting regimens. We also discuss recent trials that highlight how dietary strategies may be combined with pharmacological therapies to treat some cancers, potentially ushering a path towards precision nutrition for cancer.

Correlations between Intestinal Microbiota and Clinical Characteristics in Colorectal Adenoma/Carcinoma

Background

Most of colorectal cancer (CRC) cases are sporadic and develop along the adenoma-carcinoma sequence. Intestinal microbial dysbiosis is involved in the development of colorectal cancer. However, there are still no absolute markers predicting the progression from adenoma to carcinoma.

Aims

To investigate the characteristics of intestinal microbiota in colorectal adenoma and carcinoma patients and the correlations with clinical characteristics.

Methods

Fecal samples were collected from 154 colorectal carcinoma patients (CRC group), 20 colorectal adenoma patients (AD group), and 199 healthy controls (control group). The intestinal microbiota was investigated by 16S rRNA gene sequencing.

Results

Compared to the healthy controls, microbial diversity was dramatically decreased in AD/CRC. At the genus level, Acidaminococcus significantly decreased with the order of control-AD-CRC (P < 0.05). Parvimonas, Peptostreptococcus, Prevotella, Butyricimonas, Alistipes, and Odoribacter were the key genera in the network of colorectal adenoma/carcinoma-associated bacteria. Combination of the top 10 most important species, including Butyricimonas synergistica, Agrobacterium larrymoorei, Bacteroides plebeius, Lachnospiraceae bacterium feline oral taxon 001, Clostridium scindens, Prevotella heparinolytica, bacterium LD2013, Streptococcus mutans, Lachnospiraceae bacterium 19gly4, and Eubacterium hallii, showed the best performance in distinguishing AD patients from CRC (AUC = 85.54%, 95% CI: 78.83%-92.25%). The clinicopathologic features, including age, sex, tumor location, differentiation degree, and TNM stage, were identified to be closely linked to the intestinal microbiome in CRC.

Conclusion

Several intestinal bacteria changed along the adenoma-carcinoma sequence and might be the potential markers for the diagnosis and treatment of colorectal adenoma/carcinoma. Intestinal microbiota characteristics in CRC should account for the host factors.

Intestinal Microbiota in Colorectal Adenoma-Carcinoma Sequence

Background

Most colorectal cancer (CRC) cases are sporadic and develop along the adenoma-carcinoma sequence. Intestinal microbial dysbiosis is involved in the development of colorectal cancer. However, there are still no absolute markers predicting the progression from adenoma to carcinoma. This study aimed to investigate the characteristics of intestinal microbiota in patients with colorectal adenoma and carcinoma and its correlations with clinical characteristics.

Methods

Fecal samples were collected from 154 patients with CRC, 20 patients with colorectal adenoma (AD) and 199 healthy controls. To analyze the differences in the intestinal microbiota, 16S rRNA gene sequencing was conducted.

Results

At the genus level, there were four significantly different genera among the three groups, namely Acidaminococcus, Alloprevotella, Mycoplasma, and Sphingobacterium, while Acidaminococcus significantly decreased with the order of Control-AD-CRC (P < 0.05). In addition, Parvimonas, Peptostreptococcus, Prevotella, Butyricimonas, Alistipes, and Odoribacter were the key genera in the network of colorectal adenoma/carcinoma-associated bacteria. The top 10 most important species, including Butyricimonas synergistica, Agrobacterium larrymoorei, Bacteroides plebeius, Lachnospiraceae bacterium feline oral taxon 001, Clostridium scindens, Prevotella heparinolytica, bacterium LD2013, Streptococcus mutans, Lachnospiraceae bacterium 19gly4, and Eubacterium hallii, showed the best performance in distinguishing AD from CRC (AUC = 85.54%, 95% CI: 78.83–92.25%). The clinicopathologic features, including age, gender, tumor location, differentiation degree, and TNM stage, were identified to be closely linked to the intestinal microbiome in CRC.

Conclusion

Several intestinal bacteria changed along the adenoma-carcinoma sequence and might be the potential markers for the diagnosis and treatment of colorectal adenoma/carcinoma. Intestinal microbiota characteristics in CRC should account for the host factors.

Berberine regulates short-chain fatty acid metabolism and alleviates the colitis-associated colorectal tumorigenesis through remodeling intestinal flora

BACKGROUND

Colitis-associated cancer (CAC) is known to be a complex combination of tumor cells, non-tumor cells and a large intestinal flora. The increasing role of intestinal flora in CAC may represent a new approach to improving CAC treatment. Berberine can reduce colorectal adenoma recurrence and inhibit colorectal carcinogenesis.

PURPOSE

Berberine has demonstrated efficacy for the control and suppression of CAC. Given the low oral absorption into the blood and large intestinal excretion of berberine, intestinal flora may be one of the important targets of berberine inhibiting the occurrence of colorectal cancer (CRC). The purpose of this study was to investigate the effects of berberine on intestinal flora in CAC mice and its ability to remodel intestinal flora to improve short-chain fatty acid metabolism.

STUDY DESIGN AND METHODS

The CAC model in mice was induced by Azoxymethane/Dextran sodium sulfate (AOM/DSS). Berberine was administered daily at doses of 50 and 100 mg/kg, and aspirin was used as the positive control. The effect of berberine on colitis-associated colorectal tumorigenesis was assessed by general imaging, tumor counting, and Ki67 staining. Intestinal flora changes were detected by 16S rDNA sequencing technology. Targeted short-chain fatty acid detection was performed by GC-MS/MS, and Lipopolysaccharide (LPS) levels in feces were quantified with an ELISA kit. The signaling pathway of TLR4/NF-κB P65/IL-6/p-STAT3 was evaluated by Western blotting and immunofluorescence. The expression levels of intestinal barrier functional biomarkers Occludin and ZO-1 were detected by immunohistochemistry. Fecal flora transplantation (FMT) was used to evaluate the effect of intestinal flora in inhibiting inflammatory cancer transformation by berberine.

RESULTS

Berberine reduced the number and load of tumors in CAC mice. Berberine remodeled the composition of pathogenic and beneficial bacteria in mice with colitis-associated colorectal tumorigenesis. Berberine treatment resulted in increases in fecal butyric acid, acetic acid and propionic acid levels, but did not alter isobutyric acid, isovaleric acid, valeric acid and caproic acid. In addition, berberine reduced LPS content in feces in mice with colitis-associated colorectal tumorigenesis. Occludin and ZO-1 were upregulated, and the TLR4/p-NF-κB p65/IL-6/p-STAT3 inflammatory-cancer transformation pathway was inhibited with berberine. The FMT results further verified that the berberine-treated intestinal flora was sufficient to alleviate the occurrence of colonic tumors associated with colitis in mice.

CONCLUSION

Our study showed that berberine alleviated the colitis-associated colorectal tumorigenesis from three equilibrium levels: (1) Pathogenic and beneficial bacteria; (2) Short-chain fatty acids and LPS produced by intestinal flora; and (3) Inflammatory cancer transformation signaling and intestinal barrier function. This study provided a new approach and experimental basis for the application of berberine in the treatment of CAC in clinical practice.

The Tissue-Associated Microbiota in Colorectal Cancer: A Systematic Review

Simple Summary

Growing evidence shows a close relationship between the microbiome and colorectal cancer, but most studies analyze fecal samples. However, solid information on the microbial community that is present locally in the intestinal tumor tissues is lacking. Therefore, the aim of this systematic review was to compile evidence on the relationship between tissue-associated microbiota and colorectal cancer. Among 5080 screened publications, 39 were eligible and included in the analysis. Despite the heterogeneity in methodologies and reporting between studies, 12 groups of bacteria with strong positive and 18 groups of bacteria with strong negative associations with colorectal cancer were identified. Such knowledge may ultimately be used in novel strategies that aim to prevent, detect, and treat colorectal cancer in the upcoming years.

Abstract

The intestinal microbiome is associated with colorectal cancer. Although the mucosal microbiota better represents an individual’s local microbiome, studies on the colorectal cancer microbiota mainly reflect knowledge obtained from fecal samples. This systematic review aimed to summarize the current evidence on the relationship between the mucosal-associated bacterial microbiota and colorectal cancer. Searches were conducted in PubMed and Web of Science databases for publications comparing the mucosal microbiome of colorectal cancer patients with that of healthy controls, or with that of non-cancerous mucosal tissues. The primary outcomes were differences in microbial diversity and taxonomy. The Newcastle-Ottawa Scale was used to assess the quality of the included studies. Of the 5080 studies identified, 39 were eligible and included in the systematic review. No consistent results were identified for the α- and β-diversity, due to high heterogeneity in reporting and to differences in metrics and statistical approaches, limiting study comparability. Qualitative synthesis of microbial taxonomy identified 12 taxa with strong positive and 18 taxa with strong negative associations with colorectal cancer. Fusobacterium, Campylobacter, Parvimonas, Peptostreptococcus, Streptococcus, and Granulicatella were defined as enriched in colorectal cancer. Despite the methodological limitations of the studies, consistent evidence on bacterial taxa associated with colorectal cancer was identified. Prospective studies in large and well-characterized patient populations will be crucial to validate these findings.

B cell-mediated regulatory mechanisms control tumor-promoting intestinal inflammation

Mechanisms underlying tumor-promoting inflammatory processes in colitis-associated colorectal cancer (CAC) remain largely elusive. Here, we provide genetic evidence for distinct B cell-mediated immunoregulatory mechanisms that protect from chronic colitis versus CAC. We demonstrate an inherent capacity of interleukin-10 (IL-10)-producing B cells to differentiate into immunoglobulin A (IgA) plasma cells (PCs) upon Toll-like receptor (TLR) activation. Our data show that B cell-derived IL-10 is essential to limit pathogenic T helper type 1 (Th1)/Th17 T cell responses during chronic colitis, while IgA PCs derived from IL-10⁺ B cells are being implicated in restraining tumorigenesis during CAC. Formation of a tumor-protective intestinal environment was associated with clonal expansion of specific types of colonic IgA PCs and development of an altered microbiota that attenuated CAC. We thus propose that regulatory B cell-mediated immunomodulation entails temporal release of IL-10, which is superseded by the generation of specific IgA affecting the microbial community, thereby controlling chronic inflammation and tumorigenesis in a distinctive but interrelated manner.

The probiotic Lactobacillus rhamnosus GG (LGG) restrains the angiogenic potential of colorectal carcinoma cells by activating a pro-resolving program via formyl peptide receptor 1

Formyl peptide receptors (FPR1, FPR2 and FPR3) are innate immune sensors of pathogen and commensal bacteria and have a role in colonic mucosa homeostasis. We identified FPR1 as a tumour suppressor in gastric cancer cells due to its ability to sustain an inflammation resolution response with antiangiogenic potential. Here, we investigate whether FPR1 exerts similar functions in colorectal carcinoma (CRC) cells. Since it has been shown that the commensal bacterium Lactobacillus rhamnosus GG (LGG) can promote intestinal epithelial homeostasis through FPR1, we explored the possibility that it could induce proresolving and antiangiogenic effects in CRC cells. We demonstrated that pharmacologic inhibition or genetic deletion of FPR1 in CRC cells caused a reduction of proresolving mediators and a consequent upregulation of angiogenic factors. The activation of FPR1 mediates opposite effects. Proresolving, antiangiogenic and homeostatic functions were also observed upon treatment of CRC cells with supernatant of LGG culture, but not of other lactic acid or nonprobiotic bacteria (i.e. Bifidobacterium bifidum or Escherichia coli). These activities of LGG are dependent on FPR1 expression and on the subsequent MAPK signalling activation. Thus, the innate immune receptor FPR1 could be a regulator of the balance between microbiota, inflammation and cancer in CRC models.

Clinical characteristics of peristomal pyoderma gangrenosum: A Single Center Retrospective Observational Study

Peristomal pyoderma gangrenosum (PPG), a variant of pyoderma gangrenosum, occurs adjacent to intestinal or urinary stomas and are typically seen in patients with active inflammatory bowel diseases (IBD). The present study evaluated 14 cases of PPG among 537 patients that had undergone ostomy surgery at Asahikawa Medical University Hospital from January 2017 to December 2021. The incidence of PPG among ostomy cases was calculated as 1.01 per 100-person-years. The median period from ostomy surgery to PPG onset was 192.5 days (36-1224 days). Significant differences in gender and ostomy subtype were observed in patients with PPG compared to all patients that had undergone ostomy surgery. IBD prevalence was comparable between groups. Topical corticosteroids or tacrolimus were sufficient for controlling PPG lesions in all cases other than one case controlled with oral prednisolone administered for a separate condition. Clinicians should be aware of recent developments in IBD therapies that may modify the risk of developing PPG. The present study results add to current knowledge of the pathogenesis of PPG.

Microbiota in Tumors: From Understanding to Application

Microbes with complex functions have been found to be a potential component in tumor microenvironments. Due to their low biomass and other obstacles, intratumor microbiota is poorly understood. Mucosal sites and normal adjacent tissues are important sources of intratumor microbiota, while hematogenous spread also leads to the invasion of microbes. Intratumor microbiota affects the progression of tumors through several mechanisms, such as DNA damage, activation of oncogenic pathways, induction of immunosuppression, and metabolization of drugs. Notably, in different types of tumors, the composition and abundance of intratumor microbiota are highly heterogeneous and may play different roles in the progression of tumors. Because of the concern in this field, several techniques such as omics and immunological methods have been used to study intratumor microbiota. Here, recent progress in this field is reviewed, including the potential sources of intratumor microbiota, their functions and related mechanisms, and their heterogeneity. Techniques that can be used to study intratumor microbiota are also discussed. Moreover, research is summarized into the development of strategies that can be used in antitumor treatment and prospects for possible future research in this field.

Cancer pharmacomicrobiomics: targeting microbiota to optimise cancer therapy outcomes

Despite the promising advances in novel cancer therapy such as immune checkpoint inhibitors (ICIs), limitations including therapeutic resistance and toxicity remain. In recent years, the relationship between gut microbiota and cancer has been extensively studied. Accumulating evidence reveals the role of microbiota in defining cancer therapeutic efficacy and toxicity. Unlike host genetics, microbiota can be easily modified via multiple strategies, including faecal microbiota transplantation (FMT), probiotics and antibiotics. Preclinical studies have identified the mechanisms on how microbes influence cancer treatment outcomes. Clinical trials have also demonstrated the potential of microbiota modulation in cancer treatments. Herein, we review the mechanistic insights of gut microbial interactions with chemotherapy and ICIs, particularly focusing on the interplay between gut bacteria and the pharmacokinetics (eg, metabolism, enzymatic degradation) or pharmacodynamics (eg, immunomodulation) of cancer treatment. The translational potential of basic findings in clinical settings is then explored, including using microbes as predictive biomarkers and microbial modulation by antibiotics, probiotics, prebiotics, dietary modulations and FMT. We further discuss the current limitations of gut microbiota modulation in patients with cancer and suggest essential directions for future study. In the era of personalised medicine, it is crucial to understand the microbiota and its interactions with cancer. Manipulating the gut microbiota to augment cancer therapeutic responses can provide new insights into cancer treatment.

A hands-free stool sampling system for monitoring intestinal health and disease

Analysis of stool offers simple, non-invasive monitoring for many gastrointestinal (GI) diseases and access to the gut microbiome, however adherence to stool sampling protocols remains a major challenge because of the prevalent dislike of handling one's feces. We present a technology that enables individual stool specimen collection from toilet wastewater for fecal protein and molecular assay. Human stool specimens and a benchtop test platform integrated with a commercial toilet were used to demonstrate reliable specimen collection over a wide range of stool consistencies by solid/liquid separation followed by spray-erosion. The obtained fecal suspensions were used to perform occult blood tests for GI cancer screening and for microbiome 16S rRNA analysis. Using occult blood home test kits, we found overall 90% agreement with standard sampling, 96% sensitivity and 86% specificity. Microbiome analysis revealed no significant difference in within-sample species diversity compared to standard sampling and specimen cross-contamination was below the detection limit of the assay. Furthermore, we report on the use of an analogue turbidity sensor to assess in real time loose stools for tracking of diarrhea. Implementation of this technology in residential settings will improve the quality of GI healthcare by facilitating increased adherence to routine stool monitoring.

Gut microbiome in gastrointestinal cancer: a friend or foe?

The impact of the gut microbiome on host health is becoming increasingly recognized. To date, there is growing evidence that the complex characteristics of the microbial community play key roles as potential biomarkers and predictors of responses in cancer therapy. Many studies have shown that altered commensal bacteria lead to cancer susceptibility and progression in diverse pathways. In this review, we critically assess the data for gut microbiota related to gastrointestinal cancer, including esophageal, gastric, pancreatic, colorectal cancer, hepatocellular carcinoma and cholangiocarcinoma. Importantly, the underlying mechanisms of gut microbiota involved in cancer occurrence, prevention and treatment are elucidated. The purpose of this review is to provide novel insights for applying this understanding to the development of new therapeutic strategies in gastrointestinal cancer by targeting the microbial community.

The Emerging Roles of Human Gut Microbiota in Gastrointestinal Cancer

The gut microbiota is composed of a large number of microorganisms with a complex structure. It participates in the decomposition, digestion, and absorption of nutrients; promotes the development of the immune system; inhibits the colonization of pathogens; and thus modulates human health. In particular, the relationship between gut microbiota and gastrointestinal tumor progression has attracted widespread concern. It was found that the gut microbiota can influence gastrointestinal tumor progression in independent ways. Here, we focused on the distribution of gut microbiota in gastrointestinal tumors and further elaborated on the impact of gut microbiota metabolites, especially short-chain fatty acids, on colorectal cancer progression. Additionally, the effects of gut microbiota on gastrointestinal tumor therapy are outlined. Finally, we put forward the possible problems in gut microbiota and the gastrointestinal oncology field and the efforts we need to make.

Gut Microbiota Signatures in Tumor, Para-Cancerous, Normal Mucosa, and Feces in Colorectal Cancer Patients

Background: Association studies have linked microbiome alterations with colorectal cancer (CRC). However, differences in tumor, para-cancerous, normal mucosal, and fecal microbiota remain to be strengthened.

Methods: We performed a study on the ecologically rich and taxonomically diverse of gut microbiota using three types of colorectal mucosa (tumor mucosa, para-cancerous mucosa, normal mucosa) and feces from 98 CRC patients. Additionally, we profiled the microbiota in the fecal occult blood test (FOBT) positive and negative groups at different sampling sites.

Results: We found striking variations between tumor mucosal microbiota and normal mucosal microbiota. However, there was no significant difference between tumor and para-cancerous mucosal microbiota, as well as between para-cancerous and normal mucosal microbiota, revealing that the para-cancerous mucosal microbiota was a transitional state between the tumor and normal mucosal microbiota. And the substantial shifts in the fecal microbiota compared to mucosal microbiota indicated the risk of using fecal microbiota to define mucosal microbiota. A strong correlation between FOBT positive and Fusobacterium was discovered, indicating this adherent-invasive genus was closely related to intestinal bleeding. Furthermore, we identified six key genera, including Fusobacterium, Gemella, Campylobacter, Peptostreptococcus, Alloprevotella, and Parvimonas, which appear to be consistently over-represented in tumor mucosa compared to normal mucosa and/or in mucosa compared to feces.

Conclusion: Compositional alterations in the microbiota existed in three types of colorectal mucosa and feces in CRC patients. Six key genera may contribute to the topographic variances in the microbiota of tumor-bearing colorectum.

High-Fat Diet Enhances the Liver Metastasis Potential of Colorectal Cancer through Microbiota Dysbiosis

Simple Summary

High-fat diet (HFD) is hypothesized to induce gut dysbiosis and promote colorectal cancer (CRC). However, the specific mechanisms involved require investigation. In this study, we established an animal model and utilized 16S sequencing to determine the effects of HFD on gut microbiota, as well as on the colon and liver. Furthermore, due to the abundance of Desulfovibrio (DSV) in the faecal samples of HFD-fed rats and CRC hepatic metastasis patients, we also conducted a DSV gavage animal experiment to determine the role of DSV in CRC development. Our study confirmed that HFD could cause microbiota dysbiosis, especially DSV enrichment, and may promote CRC initiation and metastasis.

Abstract

Obesity, metabolic changes, and intestinal microbiota disruption significantly affect tumorigenesis and metastasis in colorectal cancer (CRC). However, the relationships among these factors remain poorly understood. In this study, we found that a high-fat diet (HFD) promoted gut barrier dysfunction and inflammation in the colorectum and liver. We further investigated gut microbiota changes through 16S rRNA sequencing of faecal samples from HFD-fed rats and CRC hepatic metastasis patients and found an abundance of Desulfovibrio (DSV). DSV could also induce barrier dysfunction in the colorectum and inflammation in the colorectum and liver, suggesting that it contributes to the formation of a microenvironment conducive to CRC tumorigenesis and metastasis. These findings highlight that HFD-induced microbiota dysbiosis, especially DSV abundance, could promote CRC initiation and metastasis.

Prediction of Pathogenic Factors in Dysbiotic Gut Microbiomes of Colorectal Cancer Patients Using Reverse Microbiomics

Background

Gut microbiome plays a crucial role in the formation and progression of colorectal cancer (CRC). To better identify the underlying gene-level pathogenic mechanisms of microbiome-associated CRC, we applied our newly developed Reverse Microbiomics (RM) to predict potential pathogenic factors using the data of microbiomes in CRC patients.

Results

Our literature search first identified 40 bacterial species enriched and 23 species depleted in the guts of CRC patients. These bacteria were systematically modeled and analyzed using the NCBI Taxonomy ontology. Ten species, including 6 enriched species (e.g., Bacteroides fragilis, Fusobacterium nucleatum and Streptococcus equinus) and 4 depleted species (e.g., Bacteroides uniformis and Streptococcus thermophilus) were chosen for follow-up comparative genomics analysis. Vaxign was used to comparatively analyze 47 genome sequences of these ten species. In total 18 autoantigens were predicted to contribute to CRC formation, six of which were reported with experimental evidence to be correlated with drug resistance and/or cell invasiveness of CRC. Interestingly, four human homology proteins (EDK89078.1, EDK87700.1, EDK89777.1, and EDK89145.1) are conserved among all enriched strains. Furthermore, we predicted 76 potential virulence factors without homology to human proteins, including two riboflavin synthase proteins, three ATP-binding cassettes (ABC) transporter protein family proteins, and 12 outer membrane proteins (OMPs). Riboflavin synthase is present in all the enriched strains but not in depleted species. The critical role of riboflavin synthase in CRC development was further identified from its hub role in our STRING-based protein-protein interaction (PPI) network analysis and from the finding of the riboflavin metabolism as the most significantly enriched pathway in our KEGG pathway analysis. A novel model of the CRC pathogenesis involving riboflavin synthase and other related proteins including TpiA and GrxC was further proposed.

Conclusions

The RM strategy was used to predict 18 autoantigens and 76 potential virulence factors from CRC-associated microbiome data. In addition to many of these autoantigens and virulence factors experimentally verified as reported in the literature, our study predicted many new pathogenetic factors and developed a new model of CRC pathogenesis involving the riboflavin synthase from the enriched colorectal bacteria and other associated proteins.

The role of microbiota in colorectal cancer

Cancer is one of the most important causes of death throughout the world, and the mortality rate is increasing significantly due to the aging of the population. One of the most common types of cancer is colorectal cancer (CRC). Human microbial ecosystems use metabolism to make important impacts on the body physiology. An intensive literature review was made to investigate the correlations between human gut microbiota and the incidence of CRC. The results of these studies show that there are differences in the composition of microbiota between CRC patients and normal people and the microorganisms in CRC patients are very different from healthy individuals. Therefore, changes in the microbiome can be used as a biomarker for the early detection of CRC. On the other hand, the intestinal flora is may be act as a powerful weapon against CRC in the future.

Cryptosporidium and colorectal cancer: a review of epidemiology and possible association

Cryptosporidiosis is an important protozoan disease with serious public health implications. The contribution of Cryptosporidium to colorectal cancer is still vaguely studied, but little evidence from experimental and epidemiological studies has suggested a possible association. This review discusses the epidemiology of cryptosporidiosis and colorectal cancer and attempts to unravel the possible link between the two diseases using epidemiological, pathological, molecular, and immunological evidence. The review stressed the need to undertake more studies in this relatively neglected field.