Gut microbiota profiles of treatment-naïve adult acute myeloid leukemia patients with neutropenic fever during intensive chemotherapy

Gut microbiota plays pivotal roles in benign and malignant hematopoiesis

Accumulated evidence emerges that dynamic changes in human gut microbiota and microbial metabolites can alter the ecological balance of symbiotic hosts. The gut microbiota plays a role in various diseases through different mechanisms. More and more attention has been paid to the effects that human microbiota extends beyond the gut. This review summarized the current understanding of the roles that gut microbiota plays in hematopoietic regulation and the occurrence and development of benign and malignant hematologic diseases. The progress of the application of microbiota in treatment was discussed in order to provide new insights into clinical diagnosis and treatment in the future.

Causal Relationship Between Gut Microbiota and Leukemia: Future Perspectives

The gut microbiota plays a crucial role in maintaining homeostasis in the human gastrointestinal tract. Numerous studies have shown a strong association between the gut microbiota and the emergence and progression of various diseases. Leukemia is one of the most common hematologic malignancies. Although standardized protocols and expert consensus have been developed for routine diagnosis and treatment, limitations remain due to individual differences. Nevertheless, a large number of studies have established a link between the gut microbiota and leukemia, with disturbances in the gut microbiota directly or indirectly affecting the development of leukemia. However, the causal relationship between the two remains unclear, and studying and exploring the causal relationship may open up entirely new avenues and protocols for use in the prevention and/or treatment of leukemia, offering new insights into diagnosis and treatment. In this review, the intricate relationship between the gut microbiota and leukemia is explored in depth, including causal associations, metabolite effects, therapeutic applications, and complications. Based on the characteristics of the gut microbiota, the future applications and prospects of gut microbiota are discussed to provide useful information for clinical treatment of leukemia.

Gut microbiome in association with chemotherapy-induced toxicities among patients with breast cancer

BACKGROUND

Little research has focused on the relationship between gut microbiome and chemotherapy-induced toxicity.

METHODS

This prospective study involves 301 patients with breast cancer who had prechemotherapy stool samples collected. Gut microbiome was sequenced by shotgun metagenomics; associations with chemotherapy-induced toxicities during first-line treatment by gut microbial diversity, composition, and metabolic pathways with severe (i.e., grade ≥3) hematological and gastrointestinal toxicities were evaluated via multivariable logistic regression.

RESULTS

High prechemotherapy α-diversity was associated with a significantly reduced risk of both severe hematological toxicity (odds ratio [OR] = 0.94; 95% CI, 0.89-0.99; p = .048) and neutropenia (OR = 0.94; 95% CI, 0.89-0.99; p = .016). A high abundance of phylum Synergistota, class Synergistia, and order Synergistales were significantly associated with a reduced risk of severe neutropenia; conversely, enrichment of phylum Firmicutes C, class Negativicutes, phylum Firmicutes I, and class Bacilli A, order Paenibacillales were significantly associated with an increased risk of severe neutropenia (p range: 0.012-2.32 × 10-3; false discovery rate <0.1). Significant positive associations were also observed between severe nausea/vomiting and high Chao1 indexes, β-diversity (p < .05), 20 species belonging to the family Lachnospiraceae, Oscillospiraceae, and Ruminococcaceae (p value range: 6.14 × 10-3 to 1.33 × 10-5; false discovery rate <0.1), and three metabolic pathways involved in reductive tricarboxylic acid cycle I and cycle II, and an incomplete reductive tricarboxylic acid cycle (p < .01). Conversely, a high abundance of species Odoribacter laneus and the pathway related to the L-proline biosynthesis II were inversely associated with severe nausea/vomiting.

CONCLUSIONS

Our study suggests that gut microbiota may be a potential preventive target to reduce chemotherapy-induced toxicity.

Study of the intestinal microbiota composition and the effect of treatment with intensive chemotherapy in patients recovered from acute leukemia

A dataset comprising metagenomes of outpatients (n = 28) with acute leukemia (AL) and healthy controls (n = 14) was analysed to investigate the associations between gut microbiota composition and metabolic activity and AL. According to the results obtained, no significant differences in the microbial diversity between AL outpatients and healthy controls were found. However, significant differences in the abundance of specific microbial clades of healthy controls and AL outpatients were found. We found some differences at taxa level. The relative abundance of Enterobacteriaceae, Prevotellaceae and Rikenellaceae was increased in AL outpatients, while Bacteirodaceae, Bifidobacteriaceae and Lachnospiraceae was decreased. Interestingly, the abundances of several taxa including Bacteroides and Faecalibacterium species showed variations based on recovery time from the last cycle of chemotherapy. Functional annotation of metagenome-assembled genomes (MAGs) revealed the presence of functional domains corresponding to therapeutic enzymes including L-asparaginase in a wide range of genera including Prevotella, Ruminococcus, Faecalibacterium, Alistipes, Akkermansia. Metabolic network modelling revealed potential symbiotic relationships between Veillonella parvula and Levyella massiliensis and several species found in the microbiota of AL outpatients. These results may contribute to develop strategies for the recovery of microbiota composition profiles in the treatment of patients with AL.

The Role of the Gut Microbiome in Hematological Cancers

Humans are in a complex symbiotic relationship with a wide range of microbial organisms, including bacteria, viruses, and fungi. The evolution and composition of the human microbiome can be an indicator of how it may affect human health and susceptibility to diseases. Microbiome alteration, termed as dysbiosis, has been linked to the pathogenesis and progression of hematological cancers. A variety of mechanisms, including epithelial barrier disruption, local chronic inflammation response trigger, antigen dis-sequestration, and molecular mimicry, have been proposed to be associated with gut microbiota. Dysbiosis may be induced or worsened by cancer therapies (such as chemotherapy and/or hematopoietic stem cell transplantation) or infection. The use of antibiotics during treatment may also promote dysbiosis, with possible long-term consequences. The aim of this review is to provide a succinct summary of the current knowledge describing the role of the microbiome in hematological cancers, as well as its influence on their therapies. Modulation of the gut microbiome, involving modifying the composition of the beneficial microorganisms in the management and treatment of hematological cancers is also discussed. Additionally discussed are the latest developments in modeling approaches and tools used for computational analyses, interpretation and better understanding of the gut microbiome data.

Gut microbiota alterations induced by intensive chemotherapy in acute myeloid leukaemia patients are associated with gut barrier dysfunction and body weight loss

BACKGROUND & AIMS

Acute myeloid leukaemia (AML) chemotherapy has been reported to impact gut microbiota composition. In this study, we investigated using a multi -omics strategy the changes in the gut microbiome induced by AML intense therapy and their association with gut barrier function and cachectic hallmarks.

METHODS

10 AML patients, allocated to standard induction chemotherapy (SIC), were recruited. Samples and data were collected before any therapeutic intervention (T0), at the end of the SIC (T1) and at discharge (T4). Gut microbiota composition and function, markers of inflammation, metabolism, gut barrier function and cachexia, as well as faecal, blood and urine metabolomes were assessed.

RESULTS

AML patients demonstrated decreased appetite, weight loss and muscle wasting during hospitalization, with an incidence of cachexia of 50%. AML intensive treatment transiently impaired the gut barrier function and led to a long-lasting change of gut microbiota composition characterized by an important loss of diversity. Lactobacillaceae and Campylobacter concisus were increased at T1 while Enterococcus faecium and Staphylococcus were increased at T4. Metabolomics analyses revealed a reduction in urinary hippurate and faecal bacterial amino acid metabolites (bAAm) (2-methylbutyrate, isovalerate, phenylacetate). Integration using DIABLO revealed a deep interconnection between all the datasets. Importantly, we identified bacteria which disappearance was associated with impaired gut barrier function (Odoribacter splanchnicus) and body weight loss (Gemmiger formicilis), suggesting these bacteria as actionable targets.

CONCLUSION

AML intensive therapy transiently impairs the gut barrier function while inducing enduring alterations in the composition and metabolic activity of the gut microbiota that associate with body weight loss.

TRIAL REGISTRATION

NCT03881826, https://clinicaltrials.gov/ct2/show/NCT03881826.

Alteration of gut microbiome and correlated amino acid metabolism are associated with acute myelocytic leukemia carcinogenesis

BACKGROUND

The aim of this study is to investigate the profiles of gut microbiota and metabolites in acute myelocytic leukemia (AML) patients treated with/without chemotherapy.

METHODS

Herein, high-throughput 16S rRNA gene sequencing was performed to analysis gut microbiota profiles, and liquid chromatography and mass spectrometry were performed to analysis metabolites profiles. The correlation between gut microbiota biomarkers identified by LEfSe and differentially expressed metabolites were determined by spearman association analysis.

RESULTS

The results showed the distinguished gut microbiota and metabolites profiles between AML patients and control individuals or AML patients treated with chemotherapy. Compared to normal populations, the ratio of Firmicutes to Bacteroidetes was increased at the phylum level than that in AML patients, and LEfSe analysis identified Collinsella and Coriobacteriaceae as biomarkers of AML patients. Differential metabolite analysis indicated that, compared to AML patients, numerous differential amino acids and analogs could be observed in control individuals and AML patients treated with chemotherapy. Interestingly, spearman association analysis demonstrated that plenty of bacteria biomarkers shows statistical correlations with differentially expressed amino acid metabolites. In addition, we found that both Collinsella and Coriobacteriaceae demonstrate remarkable positive correlation with hydroxyprolyl-hydroxyproline, prolyl-tyrosine, and tyrosyl-proline.

CONCLUSION

In conclusion, our present study investigated the role of the gut-microbiome-metabolome axis in AML and revealed the possibility of AML treatment by gut-microbiome-metabolome axis in the further.

Gut microbiota associated with the mitigation effect of synbiotics on adverse events of neoadjuvant chemotherapy in patients with esophageal cancer: A retrospective exploratory study

Introduction. Our synbiotics (Lacticaseibacillus paracasei strain Shirota, Bifidobacterium breve strain Yakult, and galacto-oligosaccharides: LBG) helps mitigate serious adverse events such as febrile neutropenia (FN) and diarrhoea in oesophageal cancer patients receiving neoadjuvant chemotherapy (NAC). Unfortunately, LBG therapy does not benefit all patients.Hypothesis/Gap Statement. Identification of the gut microbiota species involved in adverse events during chemotherapy could help predict the onset of adverse events. Identification of the gut microbiota that influence the efficacy of LBG could also help establish a diagnostic method to identify patients who will respond to LBG before the initiation of therapy.Aim. To identify the gut microbiota involved in adverse events during NAC and that affect the efficacy of LBG therapy.Methodology. This study was ancillary to a parent randomized controlled trial in which 81 oesophageal cancer patients were recruited and administered either prophylactic antibiotics or LBG combined with enteral nutrition (LBG+EN). The study included 73 of 81 patients from whom faecal samples were collected both before and after NAC. The gut microbiota was analysed using 16S rRNA gene amplicon sequencing and compared based on the degree of NAC-associated adverse events. Furthermore, the association between the counts of identified bacteria and adverse events and the mitigation effect of LBG+EN was also analysed.Results. The abundance of Anaerostipes hadrus and Bifidobacterium pseudocatenulatum in patients with no FN or only mild diarrhoea was significantly higher (P<0.05) compared to those with FN or severe diarrhoea. Moreover, subgroup analyses of patients receiving LBG+EN showed that the faecal A. hadrus count before NAC was significantly associated with a risk of developing FN (OR, 0.11; 95 % CI, 0.01-0.60, P=0.019). The faecal A. hadrus count after NAC was positively correlated with intestinal concentrations of acetic acid (P=0.0007) and butyric acid (P=0.00005).Conclusion. Anaerostipes hadrus and B. pseudocatenulatum may be involved in the ameliorating adverse events and can thus be used to identify beforehand patients that would benefit from LBG+EN during NAC. These results also suggest that LBG+EN would be useful in the development of measures to prevent adverse events during NAC.

Gut microbiota in acute leukemia: Current evidence and future directions

Gut microbiota includes a large number of microorganisms inhabiting the human gastrointestinal tract, which show a wide range of physiological functions, including digestion, metabolism, immunity, neural development, etc., and are considered to play an increasingly important role in health and disease. A large number of studies have shown that gut microbiota are closely associated with the onset and development of several diseases. In particular, the interaction between gut microbiota and cancer has recently attracted scholars' attention. Acute leukemia (AL) is a common hematologic malignancy, especially in children. Microbiota can affect hematopoietic function, and the effects of chemotherapy and immunotherapy on AL are noteworthy. The composition and diversity of gut microbiota are important factors that influence and predict the complications and prognosis of AL after chemotherapy or hematopoietic stem cell transplantation. Probiotics, prebiotics, fecal microbiota transplantation, and dietary regulation may reduce side effects of leukemia therapy, improve response to treatment, and improve prognosis. This review concentrated on the role of the gut microbiota in the onset and development of AL, the response and side effects of chemotherapy drugs, infection during treatment, and therapeutic efficacy. According to the characteristics of gut microbes, the applications and prospects of microbial preparations were discussed.

Diet-derived metabolites and mucus link the gut microbiome to fever after cytotoxic cancer treatment

Not all patients with cancer and severe neutropenia develop fever, and the fecal microbiome may play a role. In a single-center study of patients undergoing hematopoietic cell transplant (n = 119), the fecal microbiome was characterized at onset of severe neutropenia. A total of 63 patients (53%) developed a subsequent fever, and their fecal microbiome displayed increased relative abundances of Akkermansia muciniphila, a species of mucin-degrading bacteria (P = 0.006, corrected for multiple comparisons). Two therapies that induce neutropenia, irradiation and melphalan, similarly expanded A. muciniphila and additionally thinned the colonic mucus layer in mice. Caloric restriction of unirradiated mice also expanded A. muciniphila and thinned the colonic mucus layer. Antibiotic treatment to eradicate A. muciniphila before caloric restriction preserved colonic mucus, whereas A. muciniphila reintroduction restored mucus thinning. Caloric restriction of unirradiated mice raised colonic luminal pH and reduced acetate, propionate, and butyrate. Culturing A. muciniphila in vitro with propionate reduced utilization of mucin as well as of fucose. Treating irradiated mice with an antibiotic targeting A. muciniphila or propionate preserved the mucus layer, suppressed translocation of flagellin, reduced inflammatory cytokines in the colon, and improved thermoregulation. These results suggest that diet, metabolites, and colonic mucus link the microbiome to neutropenic fever and may guide future microbiome-based preventive strategies.

Cancer-Associated Microbiota: From Mechanisms of Disease Causation to Microbiota-Centric Anti-Cancer Approaches

Helicobacter pylori infection is the only well-established bacterial cause of cancer. However, due to the integral role of tissue-resident commensals in maintaining tissue-specific immunometabolic homeostasis, accumulated evidence suggests that an imbalance of tissue-resident microbiota that are otherwise considered as commensals, can also promote various types of cancers. Therefore, the present review discusses compelling evidence linking tissue-resident microbiota (especially gut bacteria) with cancer initiation and progression. Experimental evidence supporting the cancer-causing role of gut commensal through the modulation of host-specific processes (e.g., bile acid metabolism, hormonal effects) or by direct DNA damage and toxicity has been discussed. The opportunistic role of commensal through pathoadaptive mutation and overcoming colonization resistance is discussed, and how chronic inflammation triggered by microbiota could be an intermediate in cancer-causing infections has been discussed. Finally, we discuss microbiota-centric strategies, including fecal microbiota transplantation, proven to be beneficial in preventing and treating cancers. Collectively, this review provides a comprehensive understanding of the role of tissue-resident microbiota, their cancer-promoting potentials, and how beneficial bacteria can be used against cancers.

Gut microbiome of healthy people and patients with hematological malignancies in Belarus

Gut microbiota plays an important role in human health and the development of various diseases. We describe the intestinal microbiome of 31 healthy individuals and 29 patients who have hematological malignancies from Belarus. Bacteria that belong to Faecalibacterium, Blautia, Bacteroides, Ruminococcus, Bifidobacterium, Prevotella, Lactobacillus, and Alistipes genera were predominant in the gut of healthy people. Based on the dominant microbiota species, two enterotype-like clusters that are driven by Bacteroides and Blautia, respectively, were identified. A significant decrease in alpha diversity and alterations in the taxonomic composition of the intestinal microbiota were observed in patients with hematological malignancies compared to healthy people. The microbiome of these patients contained a high proportion of Bacteroides, Blautia, Faecalibacterium, Lactobacillus, Prevotella, Alistipes, Enterococcus, Escherichia-Shigella, Ruminococcus gnavus group, Streptococcus, and Roseburia. An increased relative abundance of Bacteroides vulgatus, Ruminococcus torques, Veillonella, Tuzzerella, Sellimonas, and a decreased number of Akkermansia, Coprococcus, Roseburia, Agathobacter, Lachnoclostridium, and Dorea were observed in individuals with hematological malignancies. Generally, the composition of the gut microbiome in patients was more variable than that of healthy individuals, and alterations in the abundance of certain microbial taxa were individually specific.

The importance of microbiota in hematology

Whilst particular infectious bacteria are well-established to be associated with hematological diseases, more recent interest has focused on the entire microbial community of mucosal surfaces. In particular, the link between hematology and the microbiota (defined as the total assemblage of microorganisms in a mucosal environment)/ microbiome (i.e. the entire ecological habitat, including organisms, their genomes and environmental conditions) is becoming more well-known. Dysbiosis, or a change in the microbiome, has been linked to the development of neoplasms, infections, inflammatory illnesses, and immune-mediated disorders, according to growing data. Microbiota may influence distant tumor microenvironment through a variety of methods, including cytokine release control, dendritic cell activation, and T-cell lymphocyte stimulation. There are numerous major implications to study the microbiome in patients with benign and malignant hematologic disorders. In this review, we investigated the structure and function of the microbiome in patients with benign and malignant hematological diseases. Chemotherapy and immunosuppressive agents used in treatment of these benign and malignant hematological diseases may cause or exacerbate dysbiosis and infectious problems. After understanding the importance of microbiota in hematological diseases, we think that use of probiotics and dietary prebiotic substances targeting microbiota modification aiming to improve hematological disease outcomes should be investigated in future studies.

Myelodysplastic Syndromes and Metabolism

Myelodysplastic syndromes (MDS) are acquired clonal stem cell disorders exhibiting ineffective hematopoiesis, dysplastic cell morphology in the bone marrow, and peripheral cytopenia at early stages; while advanced stages carry a high risk for transformation into acute myeloid leukemia (AML). Genetic alterations are integral to the pathogenesis of MDS. However, it remains unclear how these genetic changes in hematopoietic stem and progenitor cells (HSPCs) occur, and how they confer an expansion advantage to the clones carrying them. Recently, inflammatory processes and changes in cellular metabolism of HSPCs and the surrounding bone marrow microenvironment have been associated with an age-related dysfunction of HSPCs and the emergence of genetic aberrations related to clonal hematopoiesis of indeterminate potential (CHIP). The present review highlights the involvement of metabolic and inflammatory pathways in the regulation of HSPC and niche cell function in MDS in comparison to healthy state and discusses how such pathways may be amenable to therapeutic interventions.