The gut microbiome protects genetically predisposed mice against leukemia
Ontology highlight
ABSTRACT: We used microarrays to investigate gene expression changes in leukemic cells from Pax5+/- mice treated with antibiotics. Precursor B cell acute lymphoblastic leukemia (pB-ALL), the most common type of childhood leukemia, is frequently characterized by the cooperation of a genetic predisposition acquired in utero and secondary oncogenic events taking place only in a fraction of predisposed children after birth. Although predisposition can be detected at birth, it is currently unknown which factors determine the development of overt leukemia in genetic carriers and how this can be potentially prevented. Experimental studies have shown that infectious stimuli promote disease onset in genetically predisposed mice. Here, we analyzed the impact of the microbiome on leukemogenesis in a mouse model (Pax5+/- mice) that faithfully mimicks genetic predisposition and leukemogenesis of human pB-ALL related to the synergy of genetic predisposition and exposure to a natural infectious environment. Employing 16S rRNA sequencing and machine learning we can accurately predict a distinct gut microbiome which is determined by a specific constitutional genetic variant. Deprivation of the gut microbiome by antibiotic treatment enhanced pB-ALL development in Pax5+/- predisposed (63% vs. 22%) but not in wildtype mice (0%). This finding was observed in the presence but also -to a lesser extent- in the absence of a natural, infectious environment (48%). The composition of the gut microbiome constitutes a biomarker signature and allows to identify specifically those Pax5+/- mice that developed leukemia. This indicates that the gut microbiome can be used to identify carriers at risk to develop leukemia and to reduce this risk by early-life interventions.
Project description:In our model the newborns of asthmatic mother mice or of mothers exposed to air pollutant particles are born with a predisposition to asthma. Gut microbiome of these pups is altered, and the transplant of the pups’ microbiome (GMT) has conferred the asthma predisposition to naïve recipients. We hypothesized that bacteria alter metabolomic profile in the gut, which polarizes the dendritic cells (DC) in the recipient by affecting epigenetic regulation in these key decision-maker cells. Here we examined DNA methylation profiles in the recipient host’s DCs to test the prediction that GMT confers alterations in DNA methylation (not seen with sterilized GMT).
Project description:We used microarrays to analyze gene expression changes in leukemic bone marrow cells from Pax5+/- and WT mice, comparing them with preleukemic bone marrow precursor B cells from both genotypes. All mice were exposed to a single low-dose irradiation (2 Gy). PAX5 is a master regulator of B-cell development, and germline mutations in PAX5 predispose individuals to B-cell acute lymphoblastic leukemia (B-ALL). While PAX5 alterations are a hallmark of B-ALL, the mechanisms linking inherited susceptibility to leukemic transformation remain poorly understood. Here, we provide in vivo genetic evidence demonstrating that reduced Pax5 dosage increases sensitivity to DNA damage, acting as a key factor in B-ALL initiation. Using a mouse model of Pax5 heterozygosity, we show that exposure to a single low-dose irradiation (2 Gy) significantly accelerates leukemia onset, establishing a direct link between genetic predisposition and environmental stress. Notably, the resulting murine B-ALLs closely resemble the human disease, exhibiting complete Pax5 loss, CD19 downregulation, and a high incidence of DNA double-strand breaks. Mechanistically, we identify Pax5 as a regulator of p53-mediated DNA damage responses in preleukemic B cells, highlighting its role beyond lineage specification. These findings provide a mechanistic framework for the interplay between PAX5 deficiency, genomic instability, and environmental factors in early B-ALL development, uncovering new potential vulnerabilities for therapeutic intervention.
Project description:We used microarrays to investigate gene expression changes in bone marrow B220+ cells from Pax5+/- and wild-type mice after ruxolitinib treatment during 2 weeks. Preventing development of B cell acute lymphoblastic leukemia (B-ALL), a disease with devastating effects in children, is a longstanding and unsolved challenge in medicine. In humans and mice, germline alterations in the Pax5 gene can lead to B-ALL. Preclinical studies have shown that this malignant transformation only occurs under an immune stress through the accumulation of secondary mutations in the JAK/STAT pathway. Here we describe that transient oral administration of ruxolitinib, a drug targeting the JAK/STAT pathway, can mitigate the risk of B-ALL in Pax5+/- mice. Although exposure to infection strongly potentiates leukemogenesis, the development of B-ALL was significantly impeded by transient in vivo treatment of Pax5+/- mice with ruxolitinib early in life (p-value=0.0332). These findings provided the first in vivo evidence for an effective preventive strategy for B-ALL development in genetically predisposed mice.
Project description:It is well-established that women are disproportionately affected by Alzheimer’s disease (AD). The mechanisms underlying this sex-specific disparity are not fully understood, but several factors that are often associated-including interactions of sex hormones, genetic factors, and the gut microbiome-likely contribute to the disease's etiology. Here, we have examined the role of sex hormones and the gut microbiome in mediating A amyloidosis and neuroinflammation in APPPS1-21 mice. We report that postnatal gut microbiome perturbation in female APPPS1-21 mice leads to an elevation in levels of circulating estradiol. Early stage ovariectomy (OVX) leads to a reduction of plasma estradiol that is correlated with a significant alteration of gut microbiome composition and reduction in A pathology. On the other hand, supplementation of OVX-treated animals with estradiol restores A burden and influences gut microbiome composition. The reduction of A pathology with OVX is paralleled by diminished levels of plaque-associated MGnD-type microglia while estradiol supplementation of OVX-treated animals leads to a restoration of activated microglia around plaques. In summary, our investigation elucidates the complex interplay between sex-specific hormonal modulations, gut microbiome dynamics, metabolic perturbations, and microglial functionality in the pathogenesis of Alzheimer's disease.
Project description:Autism spectrum disorder (ASD) is a heterogenous neurodevelopmental disorder with complex pathophysiology including both genetic and environmental factors. Recent evidence demonstrates the gut microbiome and its resultant metabolome can influence brain and behavior and have been implicated in ASD. To investigate gene by microbiome interactions in a model for genetic risk of ASD, we utilize mutant mice carrying a deletion of the ASD-associated Shank3 gene (Shank3KO). Shank3KO have altered microbiome composition and function at baseline in addition to social deficits. Further depletion of the microbiome with antibiotics exacerbates social deficits in Shank3KO, and results in transcriptional changes in the frontal cortex. Supplementation with the microbial metabolite acetate leads to reversal of social behavioral phenotypes even in mice with a depleted microbiome, and significantly alters transcriptional regulation in the prefrontal cortex. These results suggest a key role for the gut microbiome and the neuroactive metabolite acetate in regulating ASD-like behaviors.
Project description:We used microarrays to investigate gene expression changes in healthy and leukemic cells from Pax5+/- and IL6+/-;Pax5+/- mice in CF and SPF housing conditions. PAX5 is one of the most frequently mutated genes in B-cell acute lymphoblastic leukemia (B-ALL), and children with inherited preleukemic PAX5 mutations are at a higher risk of developing the disease. Abnormal profiles of inflammatory markers can be detected in neonatal blood spot samples of children who later developed B-cell precursor B-ALL. However, how inflammatory signals contribute to B-ALL development is unclear. Here, we demonstrate that Pax5 loss results in the enhanced production of the inflammatory cytokine interleukin-6 (IL-6), which appears to act in an autocrine fashion to promote leukemia growth. In vivo genetic downregulation of IL-6 in Pax5 mutant mice retards B-cell leukemogenesis. In vivo pharmacologic inhibition of IL-6 with a neutralizing IL-6 antibody in Pax5 mutant mice with B-ALL clears leukemic cells. This exciting novel IL 6 signaling paradigm identified in mice was also substantiated in humans. Altogether, our studies establish aberrant IL6 expression caused by Pax5 loss as a hallmark of Pax5-dependent B-ALL and the IL6 as a therapeutic vulnerability for B-ALL characterized by PAX5 loss.
Project description:The transcription factors EBF1 and PAX5 are frequently mutated in B cell acute lymphoblastic leukemia (B-ALL). We demonstrate that Pax5+/- x Ebf1+/- compound heterozygous mice develop leukemia with high penetrance. Similar results were seen in Pax5+/- x Ikzf1+/- and Ebf1+/- x Ikzf1+/- mice for B-ALL, or in Tcf7+/- x Ikzf1+/- mice for T cell leukemia. To identify genetic defects that cooperate with Pax5 and Ebf1 compound heterozygosity to initiate leukemia, we carried out a Sleeping Beauty transposon screen. This screen identified a number of cooperating partners including gain-of-function mutations in Stat5 (~65%) and Jak1 (~68%), as well as loss-of-function mutations in Cblb (61%) and Myb (32%). These findings highlight the key role of JAK/STAT5 signaling in cooperating with Pax5 and Ebf1 compound haploinsufficiency to drive B cell transformation. Moreover, these studies pointed to unexpected roles for loss of function mutations in Cblb and Myb in B cell transformation. Subsequent RNA-Seq studies on WT, Pax5+/-, Ebf1+/-, Pax5+/- x Ebf1+/- pre-leukemic, Pax5+/- x Ebf1+/- leukemic cells and Pax5+/- x Ebf1+/- Sleeping Beauty leukemic cells demonstrated upregulation of a PDK1>SGK3>MYC pathway; treatment of Pax5+/- x Ebf1+/- leukemias with PDK1 specific inhibitors blocked their proliferation in vitro. Finally, we identified conserved transcriptional variation in a subset of genes between human leukemias and our mouse B-ALL models. Thus, compound haploinsufficiency for B cell transcription factors likely plays a critical role in transformation of human B cells and suggest that newly developed PDK1 inhibitors may be effective for treating patients characterized by such defects.
Project description:The transcription factors EBF1 and PAX5 are frequently mutated in B cell acute lymphoblastic leukemia (B-ALL). We demonstrate that Pax5+/- x Ebf1+/- compound heterozygous mice develop leukemia with high penetrance. Similar results were seen in Pax5+/- x Ikzf1+/- and Ebf1+/- x Ikzf1+/- mice for B-ALL, or in Tcf7+/- x Ikzf1+/- mice for T cell leukemia. To identify genetic defects that cooperate with Pax5 and Ebf1 compound heterozygosity to initiate leukemia, we carried out a Sleeping Beauty transposon screen. This screen identified a number of cooperating partners including gain-of-function mutations in Stat5 (~65%) and Jak1 (~68%), as well as loss-of-function mutations in Cblb (61%) and Myb (32%). These findings highlight the key role of JAK/STAT5 signaling in cooperating with Pax5 and Ebf1 compound haploinsufficiency to drive B cell transformation. Moreover, these studies pointed to unexpected roles for loss of function mutations in Cblb and Myb in B cell transformation. Subsequent RNA-Seq studies on WT, Pax5+/-, Ebf1+/-, Pax5+/- x Ebf1+/- pre-leukemic, Pax5+/- x Ebf1+/- leukemic cells and Pax5+/- x Ebf1+/- Sleeping Beauty leukemic cells demonstrated upregulation of a PDK1>SGK3>MYC pathway; treatment of Pax5+/- x Ebf1+/- leukemias with PDK1 specific inhibitors blocked their proliferation in vitro. Finally, we identified conserved transcriptional variation in a subset of genes between human leukemias and our mouse B-ALL models. Thus, compound haploinsufficiency for B cell transcription factors likely plays a critical role in transformation of human B cells and suggest that newly developed PDK1 inhibitors may be effective for treating patients characterized by such defects.
Project description:Cognitive impairment (CI) is a prevalent neurological condition characterized deficient attention, causal reasoning, learning and/or memory. Many genetic and environmental factors increase risk for CI, and the gut microbiome is increasingly implicated. However, the identity of gut microbes associated with CI risk, their effects on CI, and their mechanisms of action remain unclear. Here we examine the gut microbiome in response to restricted diet and intermittent hypoxia, known environmental risk factors for CI. Modeling the environmental factors together in mice potentiates CI and alters the gut microbiota. Depleting the microbiome by antibiotic treatment or germ-free rearing prevents the adverse effects of environmental risk on CI, whereas transplantation of the risk-associated microbiome into naïve mice confers CI. Parallel sequencing and gnotobiotic approaches identify the pathobiont Bilophila wadsworthia as enriched by the environmental risk factors for CI and as sufficient to induce CI. Consistent with CI-related behavioral abnormalities, B. wadsworthia and the risk-associated microbiome disrupt hippocampal activity, neurogenesis and gene expression. The CI induced by B. wadsworthia and by environmental risk factors is associated with microbiome-dependent increases in intestinal IFNy-producing Th1 cells. Inhibiting Th1 cells abrogates the adverse effects of both B. wadsworthia and environmental risk factors on CI. Together, these findings identify select gut bacteria that contribute to environmental risk for CI in mice by promoting inflammation and hippocampal dysfunction.