Rozich, I. | Search bioRxiv

bioRxiv2022

Modulation of adaptive immune responses by Akkermansia muciniphila is restricted to an early life window in NOD mice

Early life microbiota drive immune system development and influence risk for immune dysfunction later in life, including the development of type 1 diabetes (T1D). Which specific early-life microbes modulate diabetes risk and the timing of these critical interactions are not well understood. To address this gap in knowledge, we screened for microbes that induce systemic IgG1 responses in young NOD mice. We isolated a strain of Akkermansia muciniphila that potently induces systemic IgG1 antibodies and peripheral regulatory T cells (pTregs). Since this mucus-degrading commensal protects NOD mice from T1D and is associated with lower risk of developing T1D in children, we investigated how A. muciniphila impacts early-life host-commensal interactions using gnotobiotic NOD mice colonized with a defined 9-member bacterial consortium that models the early life microbiome. We find that A. muciniphila potently induces pTregs and enhances antibody responses to other commensal microbes. Remarkably, these effects only occur when A. muciniphila colonizes NOD mice prior to weaning, establishing that the specific window of exposure to A. muciniphila shapes adaptive immune system development in diabetes-susceptible NOD mice. This time dependence provides important evidence that early-life exposure may enhance microbiota-based therapies to prevent T1D. One Sentence SummaryAkkermansia muciniphila induces peripheral Tregs and enhances antibody responses to itself and other commensals during an early life window.

immunology↗

bioRxiv2020

Single-cell multi-omics reveals elevated plasticity and stem-cell-like blasts relevant to the poor prognosis of KMT2A-rearranged leukemia

Infant ALL is a devastating malignancy caused by rearrangements of the KMT2A gene (KMT2A-r) in approximately 70% of patients. The outcome is dismal and younger age at diagnosis is associated with increased risk of relapse. To discover age-specific differences and critical drivers that mediate the poor outcome in KMT2A-r ALL, we subjected KMT2A-r leukemias and normal hematopoietic cells from patients of different ages to multi-omic single cell analysis using scRNA-Seq, scATAC-Seq and snmC-Seq2. We uncovered the following critical new insights: Leukemia cells from infants younger than 6 months have a greatly increased lineage plasticity and contain a hematopoietic stem and progenitor-like (HSPC-like) population compared to older infants. We identified an immunosuppressive signaling circuit between the HSPC-like blasts and cytotoxic lymphocytes in younger patients. Both observations offer a compelling explanation for the ability of leukemias in young infants to evade chemotherapy and immune mediated control. Our analysis also revealed pre-existing lymphomyeloid primed progenitor and myeloid blasts at initial diagnosis of B-ALL. Tracking of leukemic clones in two patients whose leukemia underwent a lineage switch documented the evolution of such clones into frank AML. These findings provide critical insights into KMT2A-r ALL and have potential clinical implications for targeted inhibitors or multi-target immunotherapy approaches. Beyond infant ALL, our study demonstrates the power of single cell multi-omics to detect tumor intrinsic and extrinsic factors affecting rare but critical subpopulations within a malignant population that ultimately determines patient outcome.

cancer biology↗