Faecal microbiota transplantation protects against radiation-induced toxicity

Bacterial supplementation in mitigation of radiation-induced gastrointestinal damage

Pelvic irradiation, a crucial treatment for pelvic malignancies, is associated with the risk of gastrointestinal (GI) damage due to the high proliferation rate of epithelial cells. The radiosensitive gastrointestinal tract acts as a dose-limiting organ. High doses of ionizing radiation can cause inflammation and rupture of mucosal barriers and can also lead to intestinal fibrosis. Intestinal damage can cause acute to chronic complications, reducing patients' quality of life. The gut microbiota plays a vital role in maintaining gut health, and any changes in the gut microbial composition can worsen damage, emphasizing the importance of therapies that target and sustain the gut microbiota during radiotherapy. One potential strategy to prevent radiation-induced GI damage is to use bacterial supplements. Research suggests that probiotic supplementation may alleviate radiation-induced gastrointestinal damage, maintaining intestinal morphology and decreasing epithelial injury in cancer patients. The observed protective effects occur through various mechanisms, including antioxidant activities, modulation of the immune response, and preservation of gut barrier function. To optimize probiotic therapies, it is imperative to elucidate these mechanisms. The efficiency of probiotics as radioprotectors is highly dependent on the time and dose of administration, and their interaction with the host immune system is a key facet of their therapeutic potential. This review explores the potential benefits of bacterial supplementation in mitigating radiation-induced GI damage and the underlying mechanism. This highlights the need for further research to establish standardized protocols and refine probiotic supplementation strategies, underscoring the potential for enhancing therapeutic outcomes in patients undergoing pelvic radiotherapy.

Probiotic Consortia Protect the Intestine Against Radiation Injury by Improving Intestinal Epithelial Homeostasis

PURPOSE

Radiation-induced intestinal injury (RIII) commonly occur during abdominal-pelvic cancer radiation therapy; however, no effective prophylactic or therapeutic agents are available to manage RIII currently. This study aimed to clarify the potential of probiotic consortium supplementation in alleviating RIII.

METHODS AND MATERIALS

Male C57BL/6J mice were orally administered a probiotic mixture comprising Bifidobacterium longum BL21, Lactobacillus paracasei LC86, and Lactobacillus plantarum Lp90 for 30 days before exposure to 13 Gy of whole abdominal irradiation. The survival rates, clinical scores, and histologic changes in the intestines of mice were assessed. The impacts of probiotic consortium treatment on intestinal stem cell proliferation, differentiation, and epithelial barrier function; oxidative stress; and inflammatory cytokines were evaluated. A comprehensive examination of the gut microbiota composition was conducted through 16S rRNA sequencing, while changes in metabolites were identified using liquid chromatography-mass spectrometry.

RESULTS

The probiotic consortium alleviated RIII, as reflected by increased survival rates, improved clinical scores, and mitigated mucosal injury. The probiotic consortium treatment exhibited enhanced therapeutic effects at the histologic level compared with individual probiotic strains, although there was no corresponding improvement in survival rates and colon length. Moreover, the probiotic consortium stimulated intestinal stem cell proliferation and differentiation, enhanced the integrity of the intestinal epithelial barrier, and regulated redox imbalance and inflammatory responses in irradiated mice. Notably, the treatment induced a restructuring of the gut microbiota composition, particularly enriching short-chain fatty acid-producing bacteria. Metabolomic analysis revealed distinctive metabolic changes associated with the probiotic consortium, including elevated levels of anti-inflammatory and antiradiation metabolites.

CONCLUSIONS

The probiotic consortium attenuated RIII by modulating the gut microbiota and metabolites, improving inflammatory symptoms, and regulating oxidative stress. These findings provide new insights into the maintenance of intestinal health with probiotic consortium supplementation and will facilitate the development of probiotic-based therapeutic strategies for RIII in clinical practice.

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.

Nutrition Intervention and Microbiome Modulation in the Management of Breast Cancer

Breast cancer (BC) is one of the most common cancers worldwide and a leading cause of cancer-related deaths among women. The escalating incidence of BC underscores the necessity of multi-level treatment. BC is a complex and heterogeneous disease involving many genetic, lifestyle, and environmental factors. Growing evidence suggests that nutrition intervention is an evolving effective prevention and treatment strategy for BC. In addition, the human microbiota, particularly the gut microbiota, is now widely recognized as a significant player contributing to health or disease status. It is also associated with the risk and development of BC. This review will focus on nutrition intervention in BC, including dietary patterns, bioactive compounds, and nutrients that affect BC prevention and therapeutic responses in both animal and human studies. Additionally, this paper examines the impacts of these nutrition interventions on modulating the composition and functionality of the gut microbiome, highlighting the microbiome-mediated mechanisms in BC. The combination treatment of nutrition factors and microbes is also discussed. Insights from this review paper emphasize the necessity of comprehensive BC management that focuses on the nutrition-microbiome axis.

Beyond the Gut: The intratumoral microbiome's influence on tumorigenesis and treatment response

The intratumoral microbiome (TM) refers to the microorganisms in the tumor tissues, including bacteria, fungi, viruses, and so on, and is distinct from the gut microbiome and circulating microbiota. TM is strongly associated with tumorigenesis, progression, metastasis, and response to therapy. This paper highlights the current status of TM. Tract sources, adjacent normal tissue, circulatory system, and concomitant tumor co-metastasis are the main origin of TM. The advanced techniques in TM analysis are comprehensively summarized. Besides, TM is involved in tumor progression through several mechanisms, including DNA damage, activation of oncogenic signaling pathways (phosphoinositide 3-kinase [PI3K], signal transducer and activator of transcription [STAT], WNT/β-catenin, and extracellular regulated protein kinases [ERK]), influence of cytokines and induce inflammatory responses, and interaction with the tumor microenvironment (anti-tumor immunity, pro-tumor immunity, and microbial-derived metabolites). Moreover, promising directions of TM in tumor therapy include immunotherapy, chemotherapy, radiotherapy, the application of probiotics/prebiotics/synbiotics, fecal microbiome transplantation, engineered microbiota, phage therapy, and oncolytic virus therapy. The inherent challenges of clinical application are also summarized. This review provides a comprehensive landscape for analyzing TM, especially the TM-related mechanisms and TM-based treatment in cancer.

A gut microbial metabolite cocktail fights against obesity through modulating the gut microbiota and hepatic leptin signaling

BACKGROUND

Excessive body weight and obesity elevate the risk of chronic non-communicable diseases. The judicious application of the gut microbiome, encompassing both microorganisms and their derived compounds, holds considerable promise in the treatment of obesity.

RESULTS

In this study, we showed that a cocktail of gut microbiota-derived metabolites, comprising indole 3-propionic acid (IPA), sodium butyrate (SB) and valeric acid (VA), alleviated various symptoms of obesity in both male and female mice subjected to a high-fat diet (HFD). The 16S ribosomal RNA (rRNA) sequencing revealed that administering the cocktail via oral gavage retained the gut microbiota composition in obese mice. Fecal microbiota transplantation using cocktail-treated mice as donors mitigated the obesity phenotype of HFD-fed mice. Transcriptomic sequencing analysis showed that the cocktail preserved the gene expression profile of hepatic tissues in obese mice, especially up-regulated the expression level of leptin receptor. Gene delivery via in vivo fluid dynamics further validated that the anti-obesity efficacy of the cocktail was dependent on leptin signaling at least partly. The cocktail also inhibited the expression of appetite stimulators in hypothalamus. Together, the metabolite cocktail combated adiposity by retaining the gut microbiota configuration and activating the hepatic leptin signaling pathway.

CONCLUSIONS

Our findings provide a sophisticated regulatory network between the gut microbiome and host, and highlight a cocktail of gut microbiota-derived metabolites, including IPA, SB, and VA, might be a prospective intervention for anti-obesity in a preclinical setting. © 2024 Society of Chemical Industry.

Microbiome in radiotherapy: an emerging approach to enhance treatment efficacy and reduce tissue injury

Radiotherapy is a widely used cancer treatment that utilizes powerful radiation to destroy cancer cells and shrink tumors. While radiation can be beneficial, it can also harm the healthy tissues surrounding the tumor. Recent research indicates that the microbiota, the collection of microorganisms in our body, may play a role in influencing the effectiveness and side effects of radiation therapy. Studies have shown that specific species of bacteria living in the stomach can influence the immune system's response to radiation, potentially increasing the effectiveness of treatment. Additionally, the microbiota may contribute to adverse effects like radiation-induced diarrhea. A potential strategy to enhance radiotherapy outcomes and capitalize on the microbiome involves using probiotics. Probiotics are living microorganisms that offer health benefits when consumed in sufficient quantities. Several studies have indicated that probiotics have the potential to alter the composition of the gut microbiota, resulting in an enhanced immune response to radiation therapy and consequently improving the efficacy of the treatment. It is important to note that radiation can disrupt the natural balance of gut bacteria, resulting in increased intestinal permeability and inflammatory conditions. These disruptions can lead to adverse effects such as diarrhea and damage to the intestinal lining. The emerging field of radiotherapy microbiome research offers a promising avenue for optimizing cancer treatment outcomes. This paper aims to provide an overview of the human microbiome and its role in augmenting radiation effectiveness while minimizing damage.

Early and long-term responses of intestinal microbiota and metabolites to 131I treatment in differentiated thyroid cancer patients

BACKGROUND

Multiple high doses of 131I therapy in patients with differentiated thyroid cancer (DTC) might disrupt the balance of gut microbiota and metabolites. This study aimed to investigate the alterations of intestinal bacteria and metabolism over two courses of 131I therapy, explore the interactions, and construct diagnostic models reflecting enteric microecology based on 131I therapy.

METHODS

A total of 81 patients were recruited for the first 131I therapy (131I-1st), among whom 16 received a second course (131I-2nd) after half a year. Fecal samples were collected 1 day before (Pre-131I-1st/2nd) and 3 days after (Post-131I-1st/2nd) 131I therapy for microbiome (16S rRNA gene sequencing) and metabolomic (LC-MS/MS) analyses.

RESULTS

A total of six microbial genera and 11 fecal metabolites enriched in three pathways were identified to show significant differences between Pre-131I-1st and other groups throughout the two courses of 131I treatment. In the Post-131I-1st group, the beneficial bacteria Bifidobacterium, Lachnoclostridium, uncultured_bacterium_f_Lachnospiraceae, and Lachnospiraceae_UCG004 were abundant and the radiation-sensitive pathways of linoleic acid (LA), arachidonic acid, and tryptophan metabolism were inhibited compared with the Pre-131I-1st group. Compared with the Pre-131I-1st group, the Pre-131I-2nd group exhibited a reduced diversity of flora and differentially expressed metabolites, with a low abundance of beneficial bacteria and dysregulated radiation-sensitive pathways. However, less significant differences in microbiota and metabolites were found between the Pre/Post-131I-2nd groups compared with those between the Pre/Post-131I-1st groups. A complex co-occurrence was observed between 6 genera and 11 metabolites, with Lachnoclostridium, Lachnospiraceae_UCG004, Escherichia-Shigella, and LA-related metabolites contributing the most. Furthermore, combined diagnostic models of charactered bacteria and metabolites answered well in the early, long-term, and dose-dependent responses for 131I therapy.

CONCLUSIONS

Different stages of 131I therapy exert various effects on gut microecology, which play an essential role in regulating radiotoxicity and predicting the therapeutic response.

Investigating the effects of radiation, T cell depletion, and bone marrow transplantation on murine gut microbiota

Microbiome research has gained much attention in recent years as the importance of gut microbiota in regulating host health becomes increasingly evident. However, the impact of radiation on the microbiota in the murine bone marrow transplantation model is still poorly understood. In this paper, we present key findings from our study on how radiation, followed by bone marrow transplantation with or without T cell depletion, impacts the microbiota in the ileum and caecum. Our findings show that radiation has different effects on the microbiota of the two intestinal regions, with the caecum showing increased interindividual variation, suggesting an impaired ability of the host to regulate microbial symbionts, consistent with the Anna Karenina principle. Additionally, we observed changes in the ileum composition, including an increase in bacterial taxa that are important modulators of host health, such as Akkermansia and Faecalibaculum. In contrast, radiation in the caecum was associated with an increased abundance of several common commensal taxa in the gut, including Lachnospiraceae and Bacteroides. Finally, we found that high doses of radiation had more substantial effects on the caecal microbiota of the T-cell-depleted group than that of the non-T-cell-depleted group. Overall, our results contribute to a better understanding of the complex relationship between radiation and the gut microbiota in the context of bone marrow transplantation and highlight the importance of considering different intestinal regions when studying microbiome responses to environmental stressors.

REGγ Mitigates Radiation-Induced Enteritis by Preserving Mucin Secretion and Sustaining Microbiome Homeostasis

Radiation-induced enteritis, a significant concern in abdominal radiation therapy, is associated closely with gut microbiota dysbiosis. The mucus layer plays a pivotal role in preventing the translocation of commensal and pathogenic microbes. Although significant expression of REGγ in intestinal epithelial cells is well established, its role in modulating the mucus layer and gut microbiota remains unknown. The current study revealed notable changes in gut microorganisms and metabolites in irradiated mice lacking REGγ, as compared to wild-type mice. Concomitant with gut microbiota dysbiosis, REGγ deficiency facilitated the infiltration of neutrophils and macrophages, thereby exacerbating intestinal inflammation after irradiation. Furthermore, fluorescence in situ hybridization assays unveiled an augmented proximity of bacteria to intestinal epithelial cells in REGγ knockout mice after irradiation. Mechanistically, deficiency of REGγ led to diminished goblet cell populations and reduced expression of key goblet cell markers, Muc2 and Tff3, observed in both murine models, minigut organoid systems and human intestinal goblet cells, indicating the intrinsic role of REGγ within goblet cells. Interestingly, although administration of broad-spectrum antibiotics did not alter the goblet cell numbers or mucin 2 (MUC2) secretion, it effectively attenuated inflammation levels in the ileum of irradiated REGγ absent mice, bringing them down to the wild-type levels. Collectively, these findings highlight the contribution of REGγ in counteracting radiation-triggered microbial imbalances and cell-autonomous regulation of mucin secretion.

Fecal Microbiota Transplantation Repairs Radiation Enteritis Through Modulating the Gut Microbiota-Mediated Tryptophan Metabolism

Radiation enteritis is a common complication of abdominal and pelvic radiotherapy. Several previous studies showed that fecal microbiota transplantation (FMT) could alleviate radiation enteritis. In this study, we investigated the efficacy of FMT in alleviating radiation enteritis and explored the mechanisms by multi-omics approaches. Briefly, C57BL/6J mice were subjected to 9 Gy irradiation to the localized abdominal field, and randomized received FMT from healthy donor mice or saline. H&E staining of harvested small intestine showed FMT decreased epithelial injury. Radiation-induced microbiota dysbiosis, characterized by a decrease in beneficial bacteria Lactobacillaceae and Lachnospiraceae, while these bacteria were restored by FMT. Fecal metabolomics analysis revealed that FMT modulated metabolic dysregulation. Two tryptophan pathway metabolites, indole-3-acetaldehyde and N-Acetyl-5-hydroxytryptamine were decreased after irradiation, whereas these metabolites showed a pronounced recovery in mice receiving FMT. Proteomics analysis of small intestine indicated that radiation enteritis triggered immune-inflammatory responses, which were potentially mitigated by FMT. In 21 patients receiving pelvic radiotherapy for cervical cancer, those who developed enteritis (n = 15) had higher abundance in Lachnospiraceae. Moreover, Indole-3-acetaldehyde was reduced after irradiation. These findings provide insights into the therapeutic effects of FMT in radiation enteritis and highlight Lachnospiraceae and the tryptophan metabolite, Indole-3-acetaldehyde may protect against radiation enteritis.

Butyrate acts as a positive allosteric modulator of the 5-HT transporter to decrease availability of 5-HT in the ileum

BACKGROUND AND PURPOSE

Radiation therapy-induced gastrointestinal distress is partly associated with the elimination of gut microbiota. The effectiveness of 5-HT receptor antagonists to treat radiation therapy-induced emesis implies a pathophysiological role of 5-HT. Peripheral 5-HT is derived from intestinal epithelium. We have investigated the role of gut microbiota in regulating intestinal 5-HT availability.

EXPERIMENTAL APPROACH

A radiation therapy murine model accompanied by faecal microbiota transplantation from donors fed different diets was investigated, and mouse ileal organoids were used for mechanistic studies. The clinical relevance was validated by a small-scale human study.

KEY RESULTS

Short-term high-fat diet (HFD) induced gut bacteria to produce butyrate. Irradiated mice receiving HFD-induced microbiome had the lowest ileal levels of 5-HT, compared with other recipients. Treatment with butyrate increased 5-HT uptake in mouse ileal organoids, assayed by the real-time tracking of a fluorescent substrate for monoamine transporters. Silencing the 5-HT transporter (SERT) in the organoids abolished butyrate-stimulated 5-HT uptake. The competitive tests using different types of selective 5-HT reuptake inhibitors suggested that butyrate acted as a positive allosteric modulator of SERT. In human gut microbiota, butyrate production was associated with the interconversion between acetate and butyrate. Faecal contents of both acetate and butyrate were negatively associated with serum 5-HT, but only butyrate was positively correlated with body mass index in humans.

CONCLUSION AND IMPLICATIONS

Short-term HFD may be beneficial for alleviating gastrointestinal reactions by increasing butyrate to suppress local 5-HT levels and providing energy to cancer patients given radiation therapy.

The Importance of Microbiota and Fecal Microbiota Transplantation in Pancreatic Disorders

The role of the intestinal microbiota in the diagnosis and treatment of pancreatic diseases is increasingly significant. Consequently, fecal microbiota transplantation (FMT) is emerging as a promising therapeutic avenue for various pancreatic disorders, including cancer, pancreatitis, and type 1 diabetes (T1D). This innovative procedure entails transferring gut microbiota from healthy donors to individuals affected by pancreatic ailments with the potential to restore intestinal balance and alleviate associated symptoms. FMT represents a pioneering approach to improve patient outcomes in pancreatic diseases, offering tailored treatments customized to individual microbiomes and specific conditions. Recent research highlights the therapeutic benefits of targeting the gut microbiota for personalized interventions in pancreatic disorders. However, a comprehensive understanding of the intricate interplay between gut microbiota and pancreatic physiology warrants further investigation. The necessity for additional studies and research endeavors remains crucial, especially in elucidating both adult and pediatric cases affected by pathological pancreatic conditions.

Emerging clinical relevance of microbiome in cancer: promising biomarkers and therapeutic targets

The profound influence of microbiota in cancer initiation and progression has been under the spotlight for years, leading to numerous researches on cancer microbiome entering clinical evaluation. As promising biomarkers and therapeutic targets, the critical involvement of microbiota in cancer clinical practice has been increasingly appreciated. Here, recent progress in this field is reviewed. We describe the potential of tumor-associated microbiota as effective diagnostic and prognostic biomarkers, respectively. In addition, we highlight the relationship between microbiota and the therapeutic efficacy, toxicity, or side effects of commonly utilized treatments for cancer, including chemotherapy, radiotherapy, and immunotherapy. Given that microbial factors influence the cancer treatment outcome, we further summarize some dominating microbial interventions and discuss the hidden risks of these strategies. This review aims to provide an overview of the applications and advancements of microbes in cancer clinical relevance.

The implication of microbiome in lungs cancer: mechanisms and strategies of cancer growth, diagnosis and therapy

Available evidence illustrates that microbiome is a promising target for the study of growth, diagnosis and therapy of various types of cancer. Lung cancer is a leading cause of cancer death worldwide. The relationship of microbiota and their products with diverse pathologic conditions has been getting large attention. The novel research suggests that the microbiome plays an important role in the growth and progression of lung cancer. The lung microbiome plays a crucial role in maintaining mucosal immunity and synchronizing the stability between tolerance and inflammation. Alteration in microbiome is identified as a critical player in the progression of lung cancer and negatively impacts the patient. Studies suggest that healthy microbiome is essential for effective therapy. Various clinical trials and research are focusing on enhancing the treatment efficacy by altering the microbiome. The regulation of microbiota will provide innovative and promising treatment strategies for the maintenance of host homeostasis and the prevention of lung cancer in lung cancer patients. In the current review article, we presented the latest progress about the involvement of microbiome in the growth and diagnosis of lung cancer. Furthermore, we also assessed the therapeutic status of the microbiome for the management and treatment of lung cancer.

Roseburia intestinalis sensitizes colorectal cancer to radiotherapy through the butyrate/OR51E1/RALB axis

The radioresistant signature of colorectal cancer (CRC) hampers the clinical utility of radiotherapy. Here, we find that fecal microbiota transplantation (FMT) potentiates the tumoricidal effects of radiation and degrades the intertwined adverse events in azoxymethane (AOM)/dextran sodium sulfate (DSS)-induced CRC mice. FMT cumulates Roseburia intestinalis (R. intestinalis) in the gastrointestinal tract. Oral gavage of R. intestinalis assembles at the CRC site and synthetizes butyrate, sensitizing CRC to radiation and alleviating intestinal toxicity in primary and CRC hepatic metastasis mouse models. R. intestinalis-derived butyrate activates OR51E1, a G-protein-coupled receptor overexpressing in patients with rectal cancer, facilitating radiogenic autophagy in CRC cells. OR51E1 shows a positive correlation with RALB in clinical rectal cancer tissues and CRC mouse model. Blockage of OR51E1/RALB signaling restrains butyrate-elicited autophagy in irradiated CRC cells. Our findings highlight that the gut commensal bacteria R. intestinalis motivates radiation-induced autophagy to accelerate CRC cell death through the butyrate/OR51E1/RALB axis and provide a promising radiosensitizer for CRC in a pre-clinical setting.

Exploring the Role of Inulin in Targeting the Gut Microbiota: An Innovative Strategy for Alleviating Colonic Fibrosis Induced By Irradiation

The use of radiation therapy to treat pelvic and abdominal cancers can lead to the development of either acute or chronic radiation enteropathy. Radiation-induced chronic colonic fibrosis is a common gastrointestinal disorder resulting from the above radiation therapy. In this study, we establish the efficacy of inulin supplements in safeguarding against colonic fibrosis caused by irradiation therapy. Studies have demonstrated that inulin supplements enhance the proliferation of bacteria responsible to produce short-chain fatty acids (SCFAs) and elevate the levels of SCFAs in feces. In a mouse model of chronic radiation enteropathy, the transplantation of gut microbiota and its metabolites from feces of inulin-treated mice were found to reduce colonic fibrosis in validation experiments. Administering inulin-derived metabolites from gut microbiota led to a notable decrease in the expression of genes linked to fibrosis and collagen production in mouse embryonic fibroblast cell line NIH/3T3. In the cell line, inulin-derived metabolites also suppressed the expression of genes linked to the extracellular matrix synthesis pathway. The results indicate a novel and practical approach to safeguarding against chronic radiation-induced colonic fibrosis.

Role of the gut microbiota in tumorigenesis and treatment

The gut microbiota is a crucial component of the intricate microecosystem within the human body that engages in interactions with the host and influences various physiological processes and pathological conditions. In recent years, the association between dysbiosis of the gut microbiota and tumorigenesis has garnered increasing attention, as it is recognized as a hallmark of cancer within the scientific community. However, only a few microorganisms have been identified as potential drivers of tumorigenesis, and enhancing the molecular understanding of this process has substantial scientific importance and clinical relevance for cancer treatment. In this review, we delineate the impact of the gut microbiota on tumorigenesis and treatment in multiple types of cancer while also analyzing the associated molecular mechanisms. Moreover, we discuss the utility of gut microbiota data in cancer diagnosis and patient stratification. We further outline current research on harnessing microorganisms for cancer treatment while also analyzing the prospects and challenges associated with this approach.

Dysbiosis of gut microbiota and metabolites is associated with radiation-induced colorectal fibrosis and is restored by adipose-derived mesenchymal stem cell therapy

AIMS

This study aimed to investigate the effects of adipose-derived mesenchymal stem cells (ADSCs) on radiation-induced colorectal fibrosis (RICF) along with the associated dysbiosis of gut microbiota and metabolites.

MAIN METHODS

Fecal microbiota were assessed through 16S rRNA gene sequencing, and the fecal metabolome was characterized using liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry. The correlation between microbiota and metabolome data was explored.

KEY FINDINGS

ADSC injection demonstrated a significant restoration of radiation-induced intestinal damage in vivo. At the phylum level, irradiated rats exhibited an increase in Bacteroidota and Campilobacterota, and a decrease in Firmicutes and Desulfobacterota, contrasting with the ADSC treatment group. Metabolomic analysis revealed 72 differently expressed metabolites (DEMs) from gas chromatography-mass spectrometry and 284 DEMs from liquid chromatography-mass spectrometry in the radiation group compared to the blank group. In the ADSC treatment group versus the radiation group, 36 DEMs from gas chromatography-mass spectrometry and 341 DEMs from liquid chromatography-mass spectrometry were identified. KEGG enrichment analysis implicated pathways such as steroid hormone biosynthesis, gap junction, primary bile acid biosynthesis, citrate cycle, cAMP signaling pathway, and alanine, aspartate, and glutamate metabolism during RICF progression and after treated with ADSCs. Correlation analysis highlighted the role of ADSCs in modulating the metabolic process of Camelledionol in fecal Bacteroides.

SIGNIFICANCE

These findings underscore the potential of ADSCs in reversing dysbiosis and restoring normal colonic flora in the context of RICF, offering valuable insights for therapeutic interventions targeting radiation-induced complications.

Targeting the gut microbiota to enhance the antitumor efficacy and attenuate the toxicity of CAR-T cell therapy: a new hope?

Chimeric antigen receptor (CAR) -T cell therapy has achieved tremendous efficacy in the treatment of hematologic malignancies and represents a promising treatment regimen for cancer. Despite the striking response in patients with hematologic malignancies, most patients with solid tumors treated with CAR-T cells have a low response rate and experience major adverse effects, which indicates the need for biomarkers that can predict and improve clinical outcomes with future CAR-T cell treatments. Recently, the role of the gut microbiota in cancer therapy has been established, and growing evidence has suggested that gut microbiota signatures may be harnessed to personally predict therapeutic response or adverse effects in optimizing CAR-T cell therapy. In this review, we discuss current understanding of CAR-T cell therapy and the gut microbiota, and the interplay between the gut microbiota and CAR-T cell therapy. Above all, we highlight potential strategies and challenges in harnessing the gut microbiota as a predictor and modifier of CAR-T cell therapy efficacy while attenuating toxicity.

Border Control: The Role of the Microbiome in Regulating Epithelial Barrier Function

The gut mucosal epithelium is one of the largest organs in the body and plays a critical role in regulating the crosstalk between the resident microbiome and the host. To this effect, the tight control of what is permitted through this barrier is of high importance. There should be restricted passage of harmful microorganisms and antigens while at the same time allowing the absorption of nutrients and water. An increased gut permeability, or "leaky gut", has been associated with a variety of diseases ranging from infections, metabolic diseases, and inflammatory and autoimmune diseases to neurological conditions. Several factors can affect gut permeability, including cytokines, dietary components, and the gut microbiome. Here, we discuss how the gut microbiome impacts the permeability of the gut epithelial barrier and how this can be harnessed for therapeutic purposes.

Nocardia rubra cell-wall skeleton mitigates whole abdominal irradiation-induced intestinal injury via regulating macrophage function

Background

Ionizing radiation (IR)-induced intestinal injury is a major side effect and dose-limiting toxicity in patients receiving radiotherapy. There is an urgent need to identify an effective and safe radioprotectant to reduce radiation-induced intestinal injury. Immunoregulation is considered an effective strategy against IR-induced injury. The purpose of this article was to investigate the protective effect of Nocardia rubra cell wall skeleton (Nr-CWS), an immunomodulator, on radiation-induced intestinal damage and to explore its potential mechanism.

Methods

C57BL/6 J male mice exposed to 12 Gy whole abdominal irradiation (WAI) were examined for survival rate, morphology and function of the intestine and spleen, as well as the gut microbiota, to comprehensively evaluate the therapeutic effects of Nr-CWS on radiation-induced intestinal and splenetic injury. To further elucidate the underlying mechanisms of Nr-CWS-mediated intestinal protection, macrophages were depleted by clodronate liposomes to determine whether Nr-CWS-induced radioprotection is macrophage dependent, and the function of peritoneal macrophages stimulated by Nr-CWS was detected in vitro.

Results

Our data showed that Nr-CWS promoted the recovery of intestinal barrier function, enhanced leucine-rich repeat-containing G protein-coupled receptor 5+ intestinal stem cell survival and the regeneration of intestinal epithelial cells, maintained intestinal flora homeostasis, protected spleen morphology and function, and improved the outcome of mice exposed to 12 Gy WAI. Mechanistic studies indicated that Nr-CWS recruited macrophages to reduce WAI-induced intestinal damage. Moreover, macrophage depletion by clodronate liposomes blocked Nr-CWS-induced radioprotection. In vitro, we found that Nr-CWS activated the nuclear factor kappa-B signaling pathway and promoted the phagocytosis and migration ability of peritoneal macrophages.

Conclusions

Our study suggests the therapeutic effect of Nr-CWS on radiation-induced intestinal injury, and provides possible therapeutic strategy and potential preventive and therapeutic drugs to alleviate it.

The role of the gut microbiome in gastrointestinal cancers

The gut microbiota present in the human digestive system is incredibly varied and is home to trillions of microorganisms. The gut microbiome is shaped at birth, while numerous genetic, dietary, and environmental variables primarily influence the microbiome composition. The importance of gut microbiota on host health is becoming more widely acknowledged. Digestion, intestinal permeability, and immunological and metabolism responses can all be affected by changes in the composition and function of the gut microbiota. There is mounting evidence that the microbial population's complex traits are important biomarkers and indicators of patient outcomes in cancer and its therapies. Numerous studies have demonstrated that changed commensal gut microorganisms contribute to the development and spread of cancer through various routes. Despite the ongoing controversy surrounding the gut microbiome and gastrointestinal cancer, accumulating evidence points to a potentially far more intricate connection than a simple cause-and-effect relationship. SIMPLE SUMMARY: Due to their high frequency and fatality rate, gastrointestinal cancers are regarded as a severe public health issue with complex medical and economic burdens. The gut microbiota may directly or indirectly interact with existing therapies like immunotherapy and chemotherapy, affecting how well a treatment works. The gut microbiome influences the immune response's activity, function, and development. Generally, certain gut bacteria impact the antitumor actions during cancer by creating particular metabolites or triggering T-cell responses. Yet, certain bacterial species have been found to promote cellular proliferation and metastasis in cancer, and comprehending these interactions in the context of cancer may help identify possible treatment targets. Notwithstanding the improvements in the field, additional research is still required to comprehend the underlying processes, examine the effects on existing therapies, and pinpoint certain bacteria and immune cells that can cause this interaction.

Indole-3-carboxaldehyde ameliorates ionizing radiation-induced hematopoietic injury by enhancing hematopoietic stem and progenitor cell quiescence

Indole-3-carboxaldehyde (I3A), one of tryptophan metabolites derived from gut microbiota, extends the lifespan of mice after high-dose ionizing radiation exposure. Persistent myelosuppression is the most common and fatal complication for victims of nuclear accidents and patients undergoing radiotherapy, with few therapeutic options available. However, whether and how I3A protects ionizing radiation-induced hematopoietic toxicity remain unknown. In this study, we demonstrated that I3A treatment effectively ameliorated radiation-induced hematopoietic injury through accelerating peripheral blood cells recovery, promoting bone marrow cellularity restoration and enhancing functional HSPC regeneration. Additionally, I3A also suppressed intracellular reactive oxygen species production and inhibited apoptosis in irradiated HSPCs. Mechanistically, I3A treatment significantly increased HSPC quiescence, thus conferring HSPCs with resistance against radiation injury. Finally, I3A treatment could improve survival of lethally irradiated mice. Taken together, our data suggest that I3A acts as a gut microbiota-derived paracrine factor that regulates HSPC regeneration and may serve as a promising therapeutic agent for ionizing radiation-induced myelosuppression.

Radiation enteropathy-related depression: A neglectable course of disease by gut bacterial dysbiosis

Radiation enteropathy (RE) is common in patients treated with radiotherapy for pelvic-abdominal cancers. Accumulating data indicate that gut commensal bacteria determine intestinal radiosensitivity. Radiotherapy can result in gut bacterial dysbiosis. Gut bacterial dysbiosis contributes to the pathogenesis of RE. Mild to moderate depressive symptoms can be observed in patients with RE in clinical settings; however, the rate of these symptoms has not been reported. Studies have demonstrated that gut bacterial dysbiosis induces depression. In the state of comorbidity, RE and depression may be understood as local and abscopal manifestations of gut bacterial disorders. The ability of comorbid depression to worsen inflammatory bowel disease (IBD) has long been demonstrated and is associated with dysfunction of cholinergic neural anti-inflammatory pathways. There is a lack of direct evidence for RE comorbid with depression. It is widely accepted that RE shares similar pathophysiologic mechanisms with IBD. Therefore, we may be able to draw on the findings of the relationship between IBD and depression. This review will explore the relationship between gut bacteria, RE, and depression in light of the available evidence and indicate a method for investigating the mechanisms of RE combined with depression. We will also describe new developments in the treatment of RE with probiotics, prebiotics, and fecal microbial transplantation.

Radiation injury and gut microbiota-based treatment

The exposure to either medical sources or accidental radiation can cause varying degrees of radiation injury (RI). RI is a common disease involving multiple human body parts and organs, yet effective treatments are currently limited. Accumulating evidence suggests gut microbiota are closely associated with the development and prevention of various RI. This article summarizes 10 common types of RI and their possible mechanisms. It also highlights the changes and potential microbiota-based treatments for RI, including probiotics, metabolites, and microbiota transplantation. Additionally, a 5P-Framework is proposed to provide a comprehensive strategy for managing RI.

Enteric α-Defensin Contributes to Recovery of Radiation-Induced Intestinal Injury by Modulating Gut Microbiota and Fecal Metabolites

The effect of ionizing radiation on the gastrointestinal tract is a common complication of abdominal and pelvic radiotherapy. However, the pathological features of radiation enteropathy and its effective medical intervention regimen is still a global challenge. Here, we explored the role and mechanism of enteric alpha-defensins (EαDs) in protecting against radiation enteropathy. To address this, we utilized EαDs-deficiency mice, in which the matrix metallopeptidase 7 to activate Paneth cell α-defensins was knockout (KO) mice, and the complementary wild-type (WT) control mice for this study. Remarkably, the KO mice were more susceptible to 5.0 Gy total-body irradiation, resulting in worse clinic scores and lower survival rate, compared with the wild-type mice. Histological examination indicated that the KO mice were subjected to slow recovery of intestinal villus and mucosa function, characterized by the reduced expression of TFF3, Glut1 and Muc2. In addition, compared with the wild-type controls, the KO mice experienced serious inflammation response in intestinal tissue, indicated by the remarkably increased expression level of IL-1β, IL-6 and IL-12. Using high-throughput sequencing analysis, we found that the intestinal bacterial community of the KO mice was more prone to dysbiosis than that of the WT mice, with significantly increased abundance of opportunistic pathogenic bacteria, such as Streptococcus sp. and Escherichia-Shigella sp., whereas remarkably decreased probiotics harboring Lactobacillus sp., Desulfovibrio sp. etc. Fecal metabolomics analysis indicated that the relative abundance of 31 metabolites arose significantly different between WT and KO mice on day 10 after radiation exposure. A subset of differential metabolites to regulate host metabolism and immunity, such as acetic acid, acetate, butanoic acid, was negatively correlated with the alteration of gut microbiota in the irradiated KO mice. This study provides new insight into EαDs contribution to the recovery of radiation-induced intestinal damage, and suggests a potential novel target to prevent the adverse effects of radiotherapy.

Fecal bacteria-free filtrate transplantation is proved as an effective way for the recovery of radiation-induced individuals in mice

Background

Ionizing radiation can cause intestinal microecological dysbiosis, resulting in changes in the composition and function of gut microbiota. Altered gut microbiota is closely related to the development and progression of radiation-induced intestinal damage. Although microbiota-oriented therapeutic options such as fecal microbiota transplantation (FMT) have shown some efficacy in treating radiation toxicity, safety concerns endure. Therefore, fecal bacteria-free filtrate transplantation (FFT), which has the potential to become a possible alternative therapy, is well worth investigating. Herein, we performed FFT in a mouse model of radiation exposure and monitored its effects on radiation damage phenotypes, gut microbiota, and metabolomic profiles to assess the effectiveness of FFT as an alternative therapy to FMT safety concerns.

Results

FFT treatment conferred radioprotection against radiation-induced toxicity, representing as better intestinal integrity, robust proinflammatory and anti-inflammatory cytokines homeostasis, and accompanied by significant shifts in gut microbiome. The bacterial compartment of recipients following FFT was characterized by an enrichment of radioprotective microorganisms (members of family Lachnospiraceae). Furthermore, metabolome data revealed increased levels of microbially generated short-chain fatty acids (SCFAs) in the feces of FFT mice.

Conclusions

FFT improves radiation-induced intestinal microecological dysbiosis by reshaping intestinal mucosal barrier function, gut microbiota configurations, and host metabolic profiles, highlighting FFT regimen as a promising safe alternative therapy for FMT is effective in the treatment of radiation intestinal injury.

Echinacoside inhibits colorectal cancer metastasis via modulating the gut microbiota and suppressing the PI3K/AKT signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Echinacoside (ECH) is the dominant phenylethanoid glycoside-structured compound identified from our developed herbal formula Huangci granule, which has been previously reported to inhibit the invasion and metastasis of CRC and prolong patients' disease-free survival duration. Though ECH has inhibitory activity against aggressive colorectal cancer (CRC) cells, its anti-metastasis effect in vivo and the action mechanism is undetermined. Given that ECH has an extremely low bioavailability and gut microbiota drives the CRC progression, we hypothesized that ECH could inhibit metastatic CRC by targeting the gut microbiome.

AIM OF THE STUDY

The purpose of this study was to investigate the impact of ECH on colorectal cancer liver metastasis in vivo and its potential mechanisms.

MATERIALS AND METHODS

An intrasplenic injection-induced liver metastatic model was established to examine the efficiency of ECH on tumor metastasis in vivo. Fecal microbiota from the model group and the ECH group were separately transplanted into pseudo-sterile CRLM mice in order to verify the role of gut flora in the ECH anti-metastatic effect. The 16S rRNA gene sequence was applied to analyze the structure and composition of the gut microbiota after ECH intervention, and the effect of ECH on short-chain fatty acid (SCFAs)-producing bacteria growth was proven by anaerobic culturing in vitro. GC-MS was applied to quantitatively analyze the serum SCFAs levels in mice. RNA-seq was performed to detect the gene changes involving tumor-promoting signaling pathway.

RESULTS

ECH inhibited CRC metastasis in a dose-dependent manner in the metastatic colorectal cancer (mCRC) mouse model. Manipulation of gut bacteria in the mCRC mouse model further proved that SCFA-generating gut bacteria played an indispensable role in mediating the antimetastatic action of ECH. Under an anaerobic condition, ECH benefited SCFA-producing microbiota without affecting the total bacterial load, presenting a dose-dependent promotion on the growth of a butyrate producer, Faecalibacterium prausnitzii (F.p). Furthermore, ECH-reshaped or F.p-colonized microbiota with a high butyrate-producing capability inhibited liver metastasis by suppressing PI3K/AKT signaling and reversing the epithelial-mesenchymal transition (EMT) process, whereas this anti-metastatic ability was abrogated by the butyrate synthase inhibitor heptanoyl-CoA.

CONCLUSION

This study demonstrated that ECH exhibits oral anti-metastatic efficacy by facilitating butyrate-producing gut bacteria, which downregulates PI3K/AKT signaling and EMT. It hints at a novel role for ECH in CRC therapy.

Microbiome in Cancer Development and Treatment

Targeting the microbiome, microbiota-derived metabolites, and related pathways represents a significant challenge in oncology. Microbiome analyses have confirmed the negative impact of cancer treatment on gut homeostasis, resulting in acute dysbiosis and severe complications, including massive inflammatory immune response, mucosal barrier disruption, and bacterial translocation across the gut epithelium. Moreover, recent studies revealed the relationship between an imbalance in the gut microbiome and treatment-related toxicity. In this review, we provide current insights into the role of the microbiome in tumor development and the impact of gut and tumor microbiomes on chemo- and immunotherapy efficacy, as well as treatment-induced late effects, including cognitive impairment and cardiotoxicity. As discussed, microbiota modulation via probiotic supplementation and fecal microbiota transplantation represents a new trend in cancer patient care, aiming to increase bacterial diversity, alleviate acute and long-term treatment-induced toxicity, and improve the response to various treatment modalities. However, a more detailed understanding of the complex relationship between the microbiome and host can significantly contribute to integrating a microbiome-based approach into clinical practice. Determination of causal correlations might lead to the identification of clinically relevant diagnostic and prognostic microbial biomarkers. Notably, restoration of intestinal homeostasis could contribute to optimizing treatment efficacy and improving cancer patient outcomes.

Gut microbiota in cancer: insights on microbial metabolites and therapeutic strategies

In recent years, the role of gut microbiota in cancer treatment has attracted substantial attention. It is now well established that gut microbiota and its metabolites significantly contribute to the incidence, treatment, and prognosis of various cancers. This review provides a comprehensive review on the pivotal role of gut microbiota and their metabolites in cancer initiation and progression. Furthermore, it evaluates the impact of gut microbiota on the efficacy and associated side effects of anticancer therapies, including radiotherapy, chemotherapy, and immunotherapy, thus emphasizing the clinical importance of gut microbiota reconstitution in cancer treatment.

Radiation-Induced Intestinal Injury: Injury Mechanism and Potential Treatment Strategies

Radiation-induced intestinal injury (RIII) is one of the most common intestinal complications caused by radiotherapy for pelvic and abdominal tumors and it seriously affects the quality of life of patients. However, the treatment of acute RIII is essentially symptomatic and nutritional support treatment and an ideal means of prevention and treatment is lacking. Researchers have conducted studies at the cellular and animal levels and found that some chemical or biological agents have good therapeutic effects on RIII and may be used as potential candidates for clinical treatment. This article reviews the injury mechanism and potential treatment strategies based on cellular and animal experiments to provide new ideas for the diagnosis and treatment of RIII in clinical settings.

Microbiota in cancer: molecular mechanisms and therapeutic interventions

The diverse bacterial populations within the symbiotic microbiota play a pivotal role in both health and disease. Microbiota modulates critical aspects of tumor biology including cell proliferation, invasion, and metastasis. This regulation occurs through mechanisms like enhancing genomic damage, hindering gene repair, activating aberrant cell signaling pathways, influencing tumor cell metabolism, promoting revascularization, and remodeling the tumor immune microenvironment. These microbiota-mediated effects significantly impact overall survival and the recurrence of tumors after surgery by affecting the efficacy of chemoradiotherapy. Moreover, leveraging the microbiota for the development of biovectors, probiotics, prebiotics, and synbiotics, in addition to utilizing antibiotics, dietary adjustments, defensins, oncolytic virotherapy, and fecal microbiota transplantation, offers promising alternatives for cancer treatment. Nonetheless, due to the extensive and diverse nature of the microbiota, along with tumor heterogeneity, the molecular mechanisms underlying the role of microbiota in cancer remain a subject of intense debate. In this context, we refocus on various cancers, delving into the molecular signaling pathways associated with the microbiota and its derivatives, the reshaping of the tumor microenvironmental matrix, and the impact on tolerance to tumor treatments such as chemotherapy and radiotherapy. This exploration aims to shed light on novel perspectives and potential applications in the field.

Single-cell RNA sequencing of intestinal crypts reveals vital events in damage repair and the double-edged sword effect of the Wnt3/β-catenin pathway in irradiated mice

In this study, we executed single-cell RNA sequencing of intestinal crypts. We analyzed the differentially expressed genes (DEGs) at different time points (the first, third, and fifth days) after 13 Gy and 15 Gy abdominal body radiation (ABR) exposure and then executed gene ontology (GO) enrichment analysis, RNA velocity analysis, cell communication analysis, and ligand‒receptor interaction analysis to explore the vital events in damage repair and the multiple effects of the Wnt3/β-catenin pathway on irradiated mice. Results from bioinformatics analysis were confirmed by a series of biological experiments. Results showed that the antibacterial response is a vital event during the damage response process after 13 Gy ABR exposure; ionizing radiation (IR) induced high heterogeneity in the transient amplification (TA) cluster, which may differentiate into mature cells and stem cells in irradiated small intestine (SI) crypts. Conducting an enrichment analysis of the DEGs between mice exposed to 13 Gy and 15 Gy ABR, we concluded that the Wnt3/β-catenin and MIF-CD74/CD44 signaling pathways may contribute to 15 Gy ABR-induced mouse death. Wnt3/β-catenin promotes the recovery of irradiated SI stem/progenitor cells, which may trigger macrophage migration inhibitory factor (MIF) release to further repair IR-induced SI injury; however, with the increase in radiation dose, activation of CD44 on macrophages provides the receptor for MIF signal transduction, initiating the inflammatory cascade response and ultimately causing a cytokine release syndrome. In contrast to previous research, we confirmed that inhibition of the Wnt3/β-catenin pathway or blockade of CD44 on the second day after 15 Gy ABR may significantly protect against ABR-induced death. This study indicates that the Wnt3/β-catenin pathway plays multiple roles in damage repair after IR exposure; we also propose a novel point that the interaction between intestinal crypt stem cells (ISCs) and macrophages through the MIF-CD74/CD44 axis may exacerbate SI damage in irradiated mice.

Akkermansia muciniphila protects the intestine from irradiation-induced injury by secretion of propionic acid

Intestinal dysbiosis frequently occurs in abdominal radiotherapy and contributes to irradiation (IR)-induced intestinal damage and inflammation. Akkermansia muciniphila (A. muciniphila) is a recently characterized probiotic, which is critical for maintaining the dynamics of the intestinal mucus layer and preserving intestinal microbiota homeostasis. However, the role of A. muciniphila in the alleviation of radiation enteritis remains unknown. In this study, we reported that the abundance of A. muciniphila was markedly reduced in the intestines of mice exposed to abdominal IR and in the feces of patients who received abdominal radiotherapy. Abundance of A. muciniphila in feces of radiotherapy patients was negatively correlated with the duration of diarrhea in patients. Administration of A. muciniphila substantially mitigated IR-induced intestinal damage and prevented mouse death. Analyzing the metabolic products of A. muciniphila revealed that propionic acid, a short-chain fatty acid secreted by the microbe, mediated the radioprotective effect. We further demonstrated that propionic acid bound to G-protein coupled receptor 43 (GRP43) on the surface of intestinal epithelia and increased histone acetylation and hence enhanced the expression of tight junction proteins occludin and ZO-1 and elevated the level of mucins, leading to enhanced integrity of intestinal epithelial barrier and reduced radiation-induced intestinal damage. Metformin, a first-line agent for the treatment of type II diabetes, promoted intestinal epithelial barrier integrity and reduced radiation intestinal damage through increasing the abundance of A. muciniphila. Together, our results demonstrated that A. muciniphila plays a critical role in the reduction of abdominal IR-induced intestinal damage. Application of probiotics or their regulators, such as metformin, could be an effective treatment for the protection of radiation exposure-damaged intestine.

The Role of Long Noncoding RNAs in Intestinal Health and Diseases: A Focus on the Intestinal Barrier

The gut is the body's largest immune organ, and the intestinal barrier prevents harmful substances such as bacteria and toxins from passing through the gastrointestinal mucosa. Intestinal barrier dysfunction is closely associated with various diseases. However, there are currently no FDA-approved therapies targeting the intestinal epithelial barriers. Long noncoding RNAs (lncRNAs), a class of RNA transcripts with a length of more than 200 nucleotides and no coding capacity, are essential for the development and regulation of a variety of biological processes and diseases. lncRNAs are involved in the intestinal barrier function and homeostasis maintenance. This article reviews the emerging role of lncRNAs in the intestinal barrier and highlights the potential applications of lncRNAs in the treatment of various intestinal diseases by reviewing the literature on cells, animal models, and clinical patients. The aim is to explore potential lncRNAs involved in the intestinal barrier and provide new ideas for the diagnosis and treatment of intestinal barrier damage-associated diseases in the clinical setting.

Dissecting the role of the gut microbiome and fecal microbiota transplantation in radio- and immunotherapy treatment of colorectal cancer

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers and poses a major burden on the human health worldwide. At the moment, treatment of CRC consists of surgery in combination with (neo)adjuvant chemotherapy and/or radiotherapy. More recently, immune checkpoint blockers (ICBs) have also been approved for CRC treatment. In addition, recent studies have shown that radiotherapy and ICBs act synergistically, with radiotherapy stimulating the immune system that is activated by ICBs. However, both treatments are also associated with severe toxicity and efficacy issues, which can lead to temporary or permanent discontinuation of these treatment programs. There's growing evidence pointing to the gut microbiome playing a role in these issues. Some microorganisms seem to contribute to radiotherapy-associated toxicity and hinder ICB efficacy, while others seem to reduce radiotherapy-associated toxicity or enhance ICB efficacy. Consequently, fecal microbiota transplantation (FMT) has been applied to reduce radio- and immunotherapy-related toxicity and enhance their efficacies. Here, we have reviewed the currently available preclinical and clinical data in CRC treatment, with a focus on how the gut microbiome influences radio- and immunotherapy toxicity and efficacy and if these treatments could benefit from FMT.

Visual analysis of colorectal cancer and gut microbiota: A bibliometric analysis from 2002 to 2022

A growing number of studies have shown that gut microbiota (GM) plays an essential role in the occurrence and development of colorectal cancer (CRC). The current body of research exploring the relationship between CRC and GM is vast. Nevertheless, bibliometric studies in this area have not yet been reported. This study aimed to explore the hotspots and frontiers of research on GM and CRC in the past 20 years, which may provide a reference for researchers in this field. The Web of Science Core Collection database was searched for publications on CRC and GM from 2002 to 2022. The scientometric softwares CiteSpace and VOSviewer were used to visually analyze the countries, institutions, authors, journals, and keywords involved in the literature. Keywords co-occurrence, cluster, and burst analysis were utilized to further explore the current state and development trends of research on GM and CRC. A total of 2158 publications were included in this study, with a noticeably rising annual publication trend. The majority of these papers are from 80 nations, primarily China and the USA. J Yu was the most active author and WS Garrett has the highest citation. Among all institutions, Shanghai Jiao Tong University has the largest number of papers. Most of the publications were published in the International Journal of Molecular Sciences, with Science being the most frequently cited journal. The 4 main clusters mainly involved probiotics, inflammation, molecular mechanisms, and research methods. Current research hotspots included "Fusobacterium nucleatum," "Escherichia coli," etc. Newly emerging research has focused predominantly on immune response, gene expression, and recent strategies for the treatment of CRC with GM. The relationship between GM and CRC will continue to be a hot research area. Changes in the composition of GM in patients with CRC, the potential molecular mechanisms as well as probiotics and natural products used in the treatment of CRC have been the focus of current research and hotspots for future studies.

Modulating the gut microbiota by probiotics, prebiotics, postbiotics, and fecal microbiota transplantation: An emerging trend in cancer patient care

Treatment resistance, together with acute and late adverse effects, represents critical issues in the management of cancer patients. Promising results from preclinical and clinical research underline the emerging trend of a microbiome-based approach in oncology. Favorable bacterial species and higher gut diversity are associated with increased treatment efficacy, mainly in chemo- and immunotherapy. On the other hand, alterations in the composition and activity of gut microbial communities are linked to intestinal dysbiosis and contribute to high treatment-induced toxicity. In this Review, we provide an overview of studies concerning gut microbiota modulation in patients with solid and hematologic malignancies with a focus on probiotics, prebiotics, postbiotics, and fecal microbiota transplantation. Targeting the gut microbiome might bring clinical benefits and improve patient outcomes. However, a deeper understanding of mechanisms and large clinical trials concerning microbiome and immunological profiling is warranted to identify safe and effective ways to incorporate microbiota-based interventions in routine clinical practice.

Exploring the complex role of gut microbiome in the development of precision medicine strategies for targeting microbial imbalance-induced colon cancer

The gut microbiome has been increasingly recognized as a key player in the development and progression of colon cancer. Alterations in the gut microbiota, known as dysbiosis, can lead to a variety of medical issues. Microbial adaptation through signals and small molecules can enhance pathogen colonization and modulate host immunity, significantly impacting disease progression. Quorum sensing peptides and molecules have been linked to the progression of colon cancer. Various interventions, such as fecal microbiota transplantation, probiotics, prebiotics, synbiotics, and antibiotics, have been used to reverse dysbiosis with mixed results and potential side effects. Thus, a personalized approach to treatment selection based on patient characteristics, such as individual gut microbiota manipulation, is necessary to prevent and treat diseases like colon cancer. With advances in metagenomic sequencing and other omics technologies, there has been a growing interest in developing precision medicine strategies for microbial imbalance-induced colon cancer. This review serves as a comprehensive synthesis of current knowledge on the gut microbiome involvement in colon cancer. By exploring the potential of utilizing the gut microbiome as a target for precision medicine, this review underscores the exciting opportunities that lie ahead. Although challenges exist, the integration of microbiome data into precision medicine approaches has the potential to revolutionize the management of colon cancer, providing patients with more personalized and effective treatment options.

The tremendous clinical potential of the microbiota in the treatment of breast cancer: the next frontier

Although significant advances have been made in the diagnosis and treatment of breast cancer (BC) in recent years, BC remains the most common cancer in women and one of the main causes of death among women worldwide. Currently, more than half of BC patients have no known risk factors, emphasizing the significance of identifying more tumor-related factors. Therefore, we urgently need to find new therapeutic strategies to improve prognosis. Increasing evidence demonstrates that the microbiota is present in a wider range of cancers beyond colorectal cancer. BC and breast tissues also have different types of microbiotas that play a key role in carcinogenesis and in modulating the efficacy of anticancer treatment, for instance, chemotherapy, radiotherapy, and immunotherapy. In recent years, studies have confirmed that the microbiota can be an important factor directly and/or indirectly affecting the occurrence, metastasis and treatment of BC by regulating different biological processes, such as estrogen metabolism, DNA damage, and bacterial metabolite production. Here, we review the different microbiota-focused studies associated with BC and explore the mechanisms of action of the microbiota in BC initiation and metastasis and its application in various therapeutic strategies. We found that the microbiota has vital clinical value in the diagnosis and treatment of BC and could be used as a biomarker for prognosis prediction. Therefore, modulation of the gut microbiota and its metabolites might be a potential target for prevention or therapy in BC.

Immune Dysfunction from Radiation Exposure

The hematopoietic system is highly sensitive to ionizing radiation. Damage to the immune system may result in opportunistic infections and hemorrhage, which could lead to mortality. Inflammation triggered by tissue damage can also lead to additional local or widespread tissue damage. The immune system is responsible for tissue repair and restoration, which is made more challenging when it is in the process of self-recovery. Because of these challenges, the Radiation and Nuclear Countermeasures Program (RNCP) and the Basic Immunology Branch (BIB) under the Division of Allergy, Immunology, and Transplantation (DAIT) within the National Institute of Allergy and Infectious Diseases (NIAID), along with partners from the Biomedical Advanced Research and Development Authority (BARDA), and the Radiation Injury Treatment Network (RITN) sponsored a two-day meeting titled Immune Dysfunction from Radiation Exposure held on September 9-10, 2020. The intent was to discuss the manifestations and mechanisms of radiation-induced immune dysfunction in people and animals, identify knowledge gaps, and discuss possible treatments to restore immune function and enhance tissue repair after irradiation.

The gut microbiome changes in wild type and IL-18 knockout mice after 9.0 Gy total body irradiation

BACKGROUND

Recent studies have shown that gut microbiome plays important roles in response to radiation exposure. IL-18, an inflammatory cytokine, is highly elevated in mice, mini-pigs and nonhuman primates after radiation exposure. Blocking IL-18 using its endogenous binding protein (IL-18BP) increases mice survival after radiation exposure by decreasing bone marrow interferon-gamma levels.

METHODS

To further characterize the roles of IL-18 in response to radiation, both wild type and IL-18 knockout (IL-18 KO) mice were exposed to 9.0 Gy total body irradiation (TBI). The 30-day survival result demonstrated that IL-18 KO mice were significantly more resistant to radiation compared to the wild type mice (p < 0.0001). Mouse faecal samples were collected at pre-radiation (d0), d1, d3, d7, d14, d21 and d29 after radiation exposure. Microbiome profiling was performed on the faecal samples using 16S and ITS sequencing technology.

RESULTS

Data analysis showed that there was significant difference in the bacterial microbiome between wild type and IL-18 KO mice. Cohousing of wild type and IL-18 KO mice decreased the bacterial microbiome difference between the two genotypes. Much fewer bacterial genera were significantly changed in wild type mice than the IL-18 KO mice after radiation exposure. The different composition of the IL-18 KO mice and wild type mice persisted even after radiation exposure. Bacterial genera that significantly correlated with other genera were identified in the IL-18 KO and wild type mice. The metabolic pathways that differentially expressed in both genotypes were identified. The animal bacterial microbiome data could be used to predict the animal's radiation status. The fungal microbiome had no significant difference regarding genotype or time after radiation exposure.

CONCLUSION

The current study helps understand the gut microbiome in different genetic backgrounds and its temporal changes after radiation exposure. Our data provide insight into the mechanisms underlying radiation-induced toxicity and help identify bacteria important in response to radiation.

Marasmius androsaceus mitigates depression-exacerbated intestinal radiation injuries through reprogramming hippocampal miRNA expression

INTRODUCTION

Cancer patients commonly experience high levels of psychological stress, which poses significant risks to their well-being. Radiotherapy is a primary treatment modality for cancer; however, it often leads to intestinal injuries in these patients. Nevertheless, the impact of mental stress on radiotherapy-intertwined complications remains unclear.

METHODS

To induce intestinal injury, we employed total abdominal irradiation in our experimental model. We conducted high-throughput sequencing to analyze the expression profile of miRNAs in the hippocampus.

RESULTS

We observed that mice with depression exhibited more severe intestinal injuries following total abdominal irradiation. Remarkably, oral administration of Marasmius androsaceus not only alleviated the depressive phenotype but also mitigated radiation-induced intestinal toxicity. Notably, this radioprotective effect was not observed in mice without depression. Depression disrupted the hippocampal miRNA expression profile in mice subjected to local irradiation of the abdomen, leading to the accumulation of miR-139-5p and miR-184-3p in the hippocampus, serum, and small intestine tissues. However, treatment with Marasmius androsaceus reprogrammed the miRNA expression signature in mice with depression. Furthermore, intravenous injection of antagomirs targeting miR-139-5p and miR-184-3p ameliorated depression, up-regulated Spn expression, reduced radiation enteritis, and improved the integrity of the small intestine in irradiated mice.

CONCLUSION

Our findings demonstrate the efficacy of Marasmius androsaceus, a small mushroom, in alleviating depression-aggravated intestinal toxicity following radiotherapy by reprogramming hippocampal miRNA expression.

Mitigative and anti-inflammatory effects of Trichostatin A against radiation-induced gastrointestinal toxicity and gut microbiota alteration in mice

PURPOSE

Radiation-induced gastrointestinal injury (RIGI) is a serious side effect of abdominal and pelvic radiotherapy, which often limits the treatment of gastrointestinal and gynaecological cancers. RIGI is also observed during accidental radiological or nuclear scenarios with no approved agents available till date to prevent or mitigate RIGI in humans. Trichostatin A (TSA), an epigenetic modulator, has been currently in clinical trials for cancer treatment and is also well known for its antibiotic and antifungal properties.

METHODS

In this study, partial body (abdominal) irradiation mice model was used to investigate the mitigative effect of TSA against gastrointestinal toxicity caused by gamma radiation. Mice were checked for alterations in mean body weight, diarrheal incidence, disease activity index and survival against 15 Gy radiation. Structural abnormalities in intestine and changes in microbiota composition were studied by histopathology and 16S rRNA sequencing of fecal samples respectively. Immunoblotting and biochemical assays were performed to check protein nitrosylation, expression of inflammatory mediators, infiltration of inflammatory cells and changes in pro-inflammatory cytokine.

RESULTS

TSA administration to C57Bl/6 mice improved radiation induced mean body weight loss, maintained better health score, reduced disease activity index and promoted survival. The 16S rRNA sequencing of fecal DNA demonstrated that TSA influenced the fecal microbiota dynamics with significant alterations in the Firmicutes/Bacteriodetes ratio. TSA effectively mitigated intestinal injury, down-regulated NF-κB, Cox-2, iNOS expression, inhibited PGE2 and protein nitrosylation levels in irradiated intestine. The upregulation of NLRP3-inflammasome complex and infiltrations of inflammatory cells in the inflamed intestine were also prevented by TSA. Subsequently, the myeloperoxidase activity in intestine alongwith serum IL-18 levels was found reduced.

CONCLUSION

These findings provide evidence that TSA inhibits inflammatory mediators, alleviates gut dysbiosis, and promotes structural restoration of the irradiated intestine. TSA, therefore, can be considered as a potential agent for mitigation of RIGI in humans.

[Relationship between chronic radiation enteritis of cervical cancer and gut microbiota]

OBJECTIVE

To explore the relationship between gut microbiota and chronic radiation enteritis of cervical cancer patients.

METHODS

Fecal samples were collected from 34 patients with cervical cancer who had received radiotherapy for at least 6 months but less than 2 years. The patients were divi-ded into mild toxicity group (mild, M) with no symptoms or mild symptoms and severe toxicity group (severe, S) with severe symptoms by clinical diagnosis of radiation enteritis, modified inflammatory bo-wel disease questionnaire (IBDQ) and Vaizey questionnaire. DNA extracted from fecal samples was sequenced and analyzed by 16S rRNA sequencing method. The analysis indexes included α-diversity, β-diversity, taxonomic composition analysis, taxonomic hierarchy tree and linear discriminant analysis (LDA) effect size (LEfSe).

RESULTS

From the perspective of species diversity, most indices of α diversity in group M were higher than those in group S. Although there was no significant difference, it also indicated a correlation between low species diversity and severity of intestinal symptoms to some extent. There was also a significant difference in the distribution of β diversity between the two groups, indicating that the microbial characteristics were different between the two groups. From the perspective of species composition, the M group had higher Firmicutes [66.5% (M) vs. 56.0% (S)] and lower Proteobacteria [4.1% (M) vs. 13.9% (S)] than the S group at the level of phyla. At the level of genus, there were also significant differences between the two groups: Shigella [2.7% (M) vs. 8.5% (S)], Faeca-libacterium [7.0% (M) vs. 2.7% (S)], Lachnospiraceae_Clostridium [1.3% (M) vs. 4.7% (S)]. Through LEfSe also found some species with statistically significant differences between the two groups. The abundance of Peptoniphilus, Azospirillum and Actinomyces in group M was significantly higher, while the abundance of Veillonellaceae, Rhodobacteraceae, and Rhodobacterales in group S was significantly higher. The taxonomic hierarchy tree also intuitively showed the difference in species composition between the two groups at each taxonomic level in space.

CONCLUSION

The severity of chronic radiation enteritis of cervical cancer is closely related to the characteristics and composition of gut microbiota.

Paneth cell dysfunction in radiation injury and radio-mitigation by human α-defensin 5

Introduction

The mechanism underlying radiation-induced gut microbiota dysbiosis is undefined. This study examined the effect of radiation on the intestinal Paneth cell α-defensin expression and its impact on microbiota composition and mucosal tissue injury and evaluated the radio-mitigative effect of human α-defensin 5 (HD5).

Methods

Adult mice were subjected to total body irradiation, and Paneth cell α-defensin expression was evaluated by measuring α-defensin mRNA by RT-PCR and α-defensin peptide levels by mass spectrometry. Vascular-to-luminal flux of FITC-inulin was measured to evaluate intestinal mucosal permeability and endotoxemia by measuring plasma lipopolysaccharide. HD5 was administered in a liquid diet 24 hours before or after irradiation. Gut microbiota was analyzed by 16S rRNA sequencing. Intestinal epithelial junctions were analyzed by immunofluorescence confocal microscopy and mucosal inflammatory response by cytokine expression. Systemic inflammation was evaluated by measuring plasma cytokine levels.

Results

Ionizing radiation reduced the Paneth cell α-defensin expression and depleted α-defensin peptides in the intestinal lumen. α-Defensin down-regulation was associated with the time-dependent alteration of gut microbiota composition, increased gut permeability, and endotoxemia. Administration of human α-defensin 5 (HD5) in the diet 24 hours before irradiation (prophylactic) significantly blocked radiation-induced gut microbiota dysbiosis, disruption of intestinal epithelial tight junction and adherens junction, mucosal barrier dysfunction, and mucosal inflammatory response. HD5, administered 24 hours after irradiation (treatment), reversed radiation-induced microbiota dysbiosis, tight junction and adherens junction disruption, and barrier dysfunction. Furthermore, HD5 treatment also prevents and reverses radiation-induced endotoxemia and systemic inflammation.

Conclusion

These data demonstrate that radiation induces Paneth cell dysfunction in the intestine, and HD5 feeding prevents and mitigates radiation-induced intestinal mucosal injury, endotoxemia, and systemic inflammation.

Gut microbiota controlling radiation-induced enteritis and intestinal regeneration

Cancer remains the second leading cause of mortality, with nearly 10 million deaths worldwide in 2020. In many cases, radiotherapy is used for its anticancer effects. However, radiation causes healthy tissue toxicity as a side effect. In intra-abdominal and pelvic malignancies, the healthy bowel is inevitably included in the radiation field, causing radiation-induced enteritis and dramatically affecting the gut microbiome. This condition is associated with significant morbidity and mortality that impairs cancer patients' and survivors' quality of life. This Review provides a critical overview of the main drivers in modulating the gut microenvironment in homeostasis, disease, and injury, focusing on gut microbial metabolites and microorganisms that influence epithelial regeneration upon radiation injury.

Cracking Brain Diseases from Gut Microbes-Mediated Metabolites for Precise Treatment

The gut-brain axis has been a subject of significant interest in recent years. Understanding the link between the gut and brain axis is crucial for the treatment of disorders. Here, the intricate components and unique relationship between gut microbiota-derived metabolites and the brain are explained in detail. Additionally, the association between gut microbiota-derived metabolites and the integrity of the blood-brain barrier and brain health is emphasized. Meanwhile, gut microbiota-derived metabolites with their recent applications, challenges and opportunities their pathways on different disease treatment are focus discussed. The prospective strategy of gut microbiota-derived metabolites potential applies to the brain disease treatments, such as Parkinson's disease and Alzheimer's disease, is proposed. This review provides a broad perspective on gut microbiota-derived metabolites characteristics facilitate understand the connection between gut and brain and pave the way for the development of a new medication delivery system for gut microbiota-derived metabolites.

Research progress and treatment of radiation enteritis and gut microbiota

Radiation enteritis is a kind of intestinal radiation injury in patients with pelvic and retroperitoneal malignancies after radiotherapy, and its occurrence and development process are very complicated. At present, studies have confirmed that intestinal microecological imbalance is an important factor in the formation of this disease. Abdominal radiation causes changes in the composition of the flora and a decrease in its diversity, which is mainly manifested by a decrease in beneficial bacterial species such as Lactobacilli and Bifidobacteria. Intestinal dysbacteriosis aggravates radiation enteritis, weakens the function of the intestinal epithelial barrier, and promotes the expression of inflammatory factors, thereby aggravating the occurrence of enteritis. Given the role of the microbiome in radiation enteritis, we suggest that the gut microbiota may be a potential biomarker for the disease. Treatment methods such as probiotics, antibiotics, and fecal microbiota transplantation are ways to correct the microbiota and may be an effective way to prevent and treat radiation enteritis. Based on a review of the relevant literature, this paper reviews the mechanism and treatment of intestinal microbes in radiation enteritis.