A new insight into acute lymphoblastic leukemia in children: influences of changed intestinal microfloras

Microbiome and pediatric leukemia, diabetes, and allergies: Systematic review and meta-analysis

BACKGROUND

Despite the different pathologies and genetic susceptibilities of childhood ALL, T1DM and allergies, these conditions share epidemiological risk factors related to timing of infectious exposures and acquisition of the gut microbiome in infancy. We have assessed whether lower microbiome diversity (Shannon Index) and shared genus/species profiles are associated with pediatric ALL, allergies, and T1DM.

METHODS AND FINDINGS

Literature search was performed using PubMed, Embase, Cochrane, and Web of Science databases. Case-control, meta-analyses, and cohort studies were considered for inclusion. Inclusion criteria: (i) subjects age 1-18 years at diagnosis, (ii) reports effect of microbiome measured prior to/at time of diagnosis/first intervention (iii) outcome of ALL, allergies, asthma, or T1DM, (iv) English text. Exclusion criteria: (i) age < 1 or >18 years at diagnosis, (ii) Down Syndrome-associated ALL, (iii) non-English text, (iv) reviews, pre-print, or abstracts, (v) heavily biased studies. Abstract and full text screening were performed by two independent reviewers. Data extraction was performed by one reviewer following PRISMA guidelines. Data were pooled using a random-effects model. Eighty-eight studies were included in the analysis, with seventy-seven in the qualitative analysis and 54 in the meta-analysis. Cases were found to have lower alpha-diversity than controls in ALL (SMD:-0.78, 95%CI:-1.21, -0.34), T1DM (SMD:-1.26, 95%CI:-3.49, 0.96), eczema (SMD:-0.34, 95%CI:-0.56, -0.12), atopy (SMD:-0.06, 95%CI:-0.34, 0.22), asthma (SMD:-0.37, 95%CI:-1.16, 0.42), and food allergy (SMD:-0.11, 95%CI:-0.63, 0.41).

CONCLUSIONS

These results highlight similarities in the microbiome diversity and composition of children with ALL, T1DM, and allergies. This is compatible with a common risk factor related to immune priming in infancy and highlights the gut microbiome as a potentially modifiable risk factor and preventative strategy for these childhood diseases.

Changes in Vitamin D and Gut Microbiota in Pediatric Hematopoietic Stem Cell Transplantation Patients with Bloodstream Infections

BACKGROUND

Vitamin D (VD) and gut microbiota (GM) are important variables in pediatric hematopoietic stem cell transplantation (HSCT) recipients with bloodstream infections (BSI). Both VD and GM play significant roles in immune regulation and in maintaining intestinal barrier function.

METHODS

This prospective case-control study included 48 consecutive pediatric patients who underwent HSCT, as well as 20 healthy children from the community. Plasma samples were collected pre- and post-HSCT, together with post-HSCT fecal samples. Serum 25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) were measured using chemiluminescence and enzyme linked immunosorbent assay, respectively. GM was analyzed by 16S rDNA next generation sequencing.

RESULTS

The incidence of BSI in pediatric HSCT recipients was 33.3% (16/48). No significant differences in serum 25(OH)D or 1,25(OH)2D3 levels were observed between the BSI and non-BSI groups either before or after transplantation, or with the healthy control group. The α-diversity of GM in BSI and non-BSI patients was significantly lower than in healthy subjects. Proteobacteria were significantly more abundant in BSI patients than in non-BSI patients (p = 0.0434) or healthy controls (p = 0.0193). Pediatric HSCT patients showed significantly higher levels of Staphylococcus (p < 0.001), Pseudomonas (p < 0.001), Enterococcus (p < 0.001), Clostridium innocuum (p = 0.0175) and Enterobacter (p = 0.0394) compared to the controls, whereas the levels of Firmicutes (p = 0.009), Actinobacteria (p < 0.001), Bifidobacterium (p < 0.001) and Faecalibacterium (p < 0.001) were significantly lower. β-diversity analysis revealed significant population differences between the three groups.

CONCLUSIONS

These results indicate there is no practical value in monitoring VD in HSCT patients. During HSCT and BSI, the GM experiences a loss of probiotics and an increase in potential pathogens.

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.

Microbial metagenomic shifts in children with acute lymphoblastic leukaemia during induction therapy and predictive biomarkers for infection

BACKGROUND

Emerging evidence has indicated a link between the gut microbiota and acute lymphoblastic leukaemia (ALL). However, the acute changes in gut microbiota during chemotherapy and the predictive value of baseline gut microbiota in infectious complication remain largely unknown.

METHODS

Faecal samples (n = 126) from children with ALL (n = 49) undergoing induction chemotherapy were collected at three timepoints, i.e., initiation of chemotherapy (baseline, T0), 7 days (T1) and 33 days (T2) after initiation of chemotherapy. Gut microbiome profile was performed via metagenomic shotgun sequencing. The bioBakery3 pipeline (Kneaddata, Metaphlan 3 and HUMAnN) was performed to assign taxonomy and functional annotations. Gut microbiome at T0 were used to predict infection during chemotherapy.

RESULTS

The microbial diversities and composition changed significantly during chemotherapy, with Escherichia coli, Klebsiella pneumoniae and Bifidobacterium longum being the most prominent species. The microbial metabolic pathways were also significantly altered during chemotherapy, including the pathway of pyruvate fermentation to acetate and lactate, and assimilatory sulfate reduction pathway. The receiver operating characteristic (ROC) models based on Bifidobacterium longum at T0 could predict infectious complications during the first month of chemotherapy with the area under the curve (AUC) of 0.720.

CONCLUSIONS

Our study provides new insights into the acute changes in microbial and functional characteristics in children with ALL during chemotherapy. The baseline gut microbiota could be potential biomarkers for infections during chemotherapy.

TRIAL REGISTRATION

The study was approved by the Ethics Committee of Zhujiang Hospital, Southern Medical University (2021-KY-171-01) and registered on http://www.chictr.org.cn (ChiCTR2200065406, Registration Date: November 4, 2022).

Cancer invasion and anaerobic bacteria: new insights into mechanisms

There is growing evidence that altered microbiota abundance of a range of specific anaerobic bacteria are associated with cancer, including Peptoniphilus spp., Porphyromonas spp., Fusobacterium spp., Fenollaria spp., Prevotella spp., Sneathia spp., Veillonella spp. and Anaerococcus spp. linked to multiple cancer types. In this review we explore these pathogenic associations. The mechanisms by which bacteria are known or predicted to interact with human cells are reviewed and we present an overview of the interlinked mechanisms and hypotheses of how multiple intracellular anaerobic bacterial pathogens may act together to cause host cell and tissue microenvironment changes associated with carcinogenesis and cancer cell invasion. These include combined effects on changes in cell signalling, DNA damage, cellular metabolism and immune evasion. Strategies for early detection and eradication of anaerobic cancer-associated bacterial pathogens that may prevent cancer progression are proposed.

The Gut Microbiome and Acute Leukemia: Implications for Early Diagnostic and New Therapies

Acute leukemia (AL), one of the hematological malignancies, shows high heterogeneity. Tremendous progresses are achieved in treating AL with novel targeted drugs and allogeneic hematopoietic stem cell transplantation, there are numerous issues including pathogenesis, early diagnosis, and therapeutic efficacy of AL to be solved. In recent years, an increasing number of studies regarding microbiome have shed more lights on the role of gut microbiota in promoting AL progression. Mechanisms related to the role of gut microbiota in enhancing AL genesis are summarized in the present work, especially on critical pathways like leaky gut, bacterial dysbiosis, microorganism-related molecular patterns, and bacterial metabolites, resulting in AL development. Additionally, the potential of gut microbiota as the biomarker for early AL diagnosis is discussed. It also outlooks therapies targeting gut microbiota for preventing AL development.

Advances in the role of gut microbiota in the regulation of the tumor microenvironment (Review)

As a protector of human health, the gut microbiota plays an important role in the development of the immune system during childhood, and the regulation of dietary habits, metabolism and immune system during adulthood. Dysregulated gut flora is not pathogenic, but it can weaken the protective effect of the immune system and cause various diseases. The tumor microenvironment is a physiological environment formed during tumor growth, which provides nutrients and growth factors necessary for tumor growth. As an important factor affecting the tumor microenvironment, the intestinal microflora affects the development of tumors through the mechanisms of gut and microflora metabolites, gene toxins and signaling pathways. The present article aimed to review the components and mechanisms of action, clinical applications, and biological targets of gut microbiota in the regulation of the tumor microenvironment. The present review provides novel insights for the future use of intestinal flora, to regulate the tumor microenvironment, to intervene in the occurrence, development, treatment and prognosis of tumors.

Gut microbiome immaturity and childhood acute lymphoblastic leukaemia

Acute lymphoblastic leukaemia (ALL) is the most common cancer of childhood. Here, we map emerging evidence suggesting that children with ALL at the time of diagnosis may have a delayed maturation of the gut microbiome compared with healthy children. This finding may be associated with early-life epidemiological factors previously identified as risk indicators for childhood ALL, including caesarean section birth, diminished breast feeding and paucity of social contacts. The consistently observed deficiency in short-chain fatty-acid-producing bacterial taxa in children with ALL has the potential to promote dysregulated immune responses and to, ultimately, increase the risk of transformation of preleukaemic clones in response to common infectious triggers. These data endorse the concept that a microbiome deficit in early life may contribute to the development of the major subtypes of childhood ALL and encourage the notion of risk-reducing microbiome-targeted intervention in the future.

Integration analysis of tumor metagenome and peripheral immunity data of diffuse large-B cell lymphoma

Background/purpose

It has been demonstrated that gut microbes are closely associated with the pathogenesis of lymphoma, but the gut microbe landscape and its association with immune cells in diffuse large B-cell lymphoma (DLBCL) remain largely unknown. In this study, we explored the associations between gut microbiota, clinical features and peripheral blood immune cell subtypes in DLBCL.

Method

A total of 87 newly diagnosed DLBCL adults were enrolled in this study. The peripheral blood samples were collected from all patients and then submitted to immune cell subtyping using full-spectral flow cytometry. Metagenomic sequencing was applied to assess the microbiota landscape of 69 of 87 newly diagnosed DLBCL patients. The microbiotas and peripheral blood immune cell subsets with significant differences between different National Comprehensive Center Network-International Prognostic Indexes (NCCN-IPIs) (low-risk, low-intermediate-risk, intermediate-high-risk, high-risk) groups were screened.

Results

A total of 10 bacterial phyla, 31 orders and 455 bacteria species were identified in 69 patients with newly diagnosed DLBCL. The abundances of 6 bacteria, including Blautia sp.CAG 257, Actinomyces sp.S6 Spd3, Streptococcus parasanguinis, Bacteroides salyersiae, Enterococcus faecalls and Streptococcus salivarius were significantly different between the low-risk, low-intermediate-risk, intermediate-high-risk and high-risk groups, among which Streptococcus parasanguinis and Streptococcus salivarius were markedly accumulated in the high-risk group. The different bacteria species were mostly enriched in the Pyridoxal 5'-phosphate biosynthesis I pathway. In addition, we found that 2 of the 6 bacteria showed close associations with the different immune cell subtypes which were also identified from different NCCN-IPIs. In detail, the abundance of Bacteroides salyersiae was negatively correlated with Treg cells, CD38+ nonrescue exhausted T cells, nature killer 3 cells and CD38+CD8+ effector memory T cells, while the abundance of Streptococcus parasanguinis was negatively correlated with HLA-DR+ NK cells, CD4+ Treg cells, HLA-DR+ NKT cells and HLA-DR+CD94+CD159c+ NKT cells.

Conclusion

This study first reveals the gut microbiota landscape of patients with newly diagnosed DLBCL and highlights the association between the gut microbiota and immunity, which may provide a new idea for the prognosis assessment and treatment of DLBCL.

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.

[Changes of intestinal flora in children with acute lymphoblastic leukemia before and after chemotherapy]

OBJECTIVES

To examine the changes of intestinal flora in children newly diagnosed with acute lymphoblastic leukemia (ALL) and the influence of chemotherapy on intestinal flora.

METHODS

Fecal samples were collected from 40 children newly diagnosed with ALL before chemotherapy and at 2 weeks, 1 month, and 2 months after chemotherapy. Ten healthy children served as the control group. 16S rDNA sequencing and analysis were performed to compare the differences in intestinal flora between the ALL and control groups and children with ALL before and after chemotherapy.

RESULTS

The ALL group had a significant reduction in the abundance of intestinal flora at 1 and 2 months after chemotherapy, with a significant reduction compared with the control group (P<0.05). Compared with the control group, the ALL group had a significant reduction in the diversity of intestinal flora before and after chemotherapy (P<0.05). At the phylum level, compared with the control group, the ALL group had a significant reduction in the relative abundance of Actinobacteria at 2 weeks, 1 month, and 2 months after chemotherapy (P<0.05) and a significant increase in the relative abundance of Proteobacteria at 1 and 2 months after chemotherapy (P<0.05). At the genus level, compared with the control group, the ALL group had a significant reduction in the relative abundance of Bifidobacterium at 2 weeks, 1 month, and 2 months after chemotherapy (P<0.05); the relative abundance of Klebsiella in the ALL group was significantly higher than that in the control group at 1 and 2 months after chemotherapy and showed a significant increase at 1 month after chemotherapy (P<0.05); the relative abundance of Faecalibacterium in the ALL group was significantly lower than that in the control group before and after chemotherapy and showed a significant reduction at 2 weeks and 1 month after chemotherapy (P<0.05). The relative abundance of Enterococcus increased significantly at 1 and 2 months after chemotherapy in the ALL group (P<0.05), and was significantly higher than that in the control group (P<0.05).

CONCLUSIONS

The diversity of intestinal flora in children with ALL is significantly lower than that in healthy children. Chemotherapy significantly reduces the abundance of intestinal flora and can reduce the abundance of some probiotic bacteria (Bifidobacterium and Faecalibacterium) and increase the abundance of pathogenic bacteria (Klebsiella and Enterococcus) in children with ALL.

Antibiotics in early life and childhood pre-B-ALL. Reasons to analyze a possible new piece in the puzzle

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer with precursor B-cell ALL (pB-ALL) accounting for ~ 85% of the cases. Childhood pB-ALL development is influenced by genetic susceptibility and host immune responses. The role of the intestinal microbiome in leukemogenesis is gaining increasing attention since Vicente-Dueñas' seminal work demonstrated that the gut microbiome is distinct in mice genetically predisposed to ALL and that the alteration of this microbiome by antibiotics is able to trigger pB-ALL in Pax5 heterozygous mice in the absence of infectious stimuli. In this review we provide an overview on novel insights on the role of the microbiome in normal and preleukemic hematopoiesis, inflammation, the effect of dysbiosis on hematopoietic stem cells and the emerging importance of the innate immune responses in the conversion from preleukemic to leukemic state in childhood ALL. Since antibiotics, which represent one of the most widely used medical interventions, alter the gut microbial composition and can cause a state of dysbiosis, this raises exciting epidemiological questions regarding the implications for antibiotic use in early life, especially in infants with a a preleukemic "first hit". Sheading light through a rigorous study on this piece of the puzzle may have broad implications for clinical practice.

Ursolic acid restores sensitivity to gemcitabine through the RAGE/NF-κB/MDR1 axis in pancreatic cancer cells and in a mouse xenograft model

Gemcitabine (GEM) is a first-line drug for pancreatic cancer therapy, but GEM resistance is easily developed in patients. Growing evidence suggests that cancer chemoprevention and suppression are highly associated with dietary phytochemical and microbiota composition. Ursolic acid (UA) has anti-inflammatory and anticancer effects; however, its role in improving cancer drug resistance in vivo remains unclear. In this study, the aim was to explore the role of UA in managing drug resistance-associated molecular mechanisms and the influence of gut microbiota. The in vitro results showed that receptor for advanced glycation end products (RAGE), nuclear factor kappa B p65 (NF-κB/p65), and multidrug resistance protein 1 (MDR1) protein levels were significantly increased in GEM-resistant pancreatic cancer cells (named MIA PaCa-2 GEMR) compared to MIA PaCa-2 cells. Downregulation of RAGE, pP65, and MDR1 protein expression not only was observed following UA treatment but also was seen in MIA PaCa-2 GEMR cells after transfection with a RAGE siRNA. Remarkably, the enhanced effects of UA coupled with GEM administration dramatically suppressed the RAGE/NF-κB/MDR1 cascade and consequently inhibited subcutaneous tumor growth. Moreover, UA could increase alpha diversity and regulate the composition of gut microbiota, especially in Ruminiclostridium 6. Taken together, these results provide the first direct evidence of MDR1 attenuation and chemosensitivity enhancement through inhibition of the RAGE/NF-κB signaling pathway in vitro and in vivo, implying that UA may be used as an adjuvant for the treatment of pancreatic cancer in the future.

Oral Microbiome Signatures in Hematological Cancers Reveal Predominance of Actinomyces and Rothia Species

The endogenous microbiome of healthy individuals in oral cavities is diverse, representing over 700 bacterial species. Imbalance in oral and gut microbiome composition and associated gene expression has been linked to different forms of hematological (blood) cancers. Our objective is to compare oral microbiome profiles of patients with blood cancers (BC group: N = 39 patients, n = 124 oral samples) to those of healthy control subjects (HC group: N = 27 subjects, n = 100 oral samples). Saliva samples and swabs of buccal mucosa, supragingival plaque, and tongue were collected from blood cancer patients and healthy controls. Next-generation sequencing (16S-rRNA gene V3-V4 region) was used to determine the relative abundance of bacterial taxa present at the genus and species levels. Differences in oral microbiome beta-diversity were determined using multivariate permutational analysis of variance (PERMANOVA). Linear discriminant analysis (LDA) effect size (LEfSe) analysis was performed to identify differentiating bacterial taxa in pairwise comparisons. The PATRIC_v3.6.7 online tool was used to determine the predominance of potential pathogenicity in the BC group. The oral microbiome beta-diversities of the BC and HC groups differed and corresponded to a reduced alpha-diversity in the BC group. LEfSe analysis showed significant LDA scores for Actinomyces and Rothia spp., differentiating the BC group from the HC group. In silico analysis using PATRIC_v3.6.7 demonstrated that the groups of bacteria possessing traits of "antibiotic resistance", "oral pathogen", and "virulence" was enriched in the BC group. Although 56% of the BC patients received antibiotics within two weeks of the oral bacterial sampling, Actinomyces genus remained the top differentiating feature in the BC group regardless of the administration of antibiotics, while Rothia dentocariosa was detected as the top differentiating feature in the BC patients who did not receive antibiotics, but not in those who received antibiotics. Further investigation is needed to better understand the interactions of certain oral species with the host immune system to better characterize clinically relevant associations with hematological cancers.