Biology subjects

Morishima, T.

Publications and source records attributed to Morishima, T..

4 recordsLinked to original sources

bioRxiv2025

Skin-derived G-CSF activates pathological granulopoiesis upon psoriasis

Psoriasis is an inflammatory skin disease initiated by environmental triggers and driven by disruption of T cell cytokine network in the cutaneous milieu. The fact that complete resolution of disease by targeting key inflammatory cytokines remains challenging indicates a contribution of other immune cells to the pathogenesis. Here, we study the role of neutrophils in psoriasis, the first-line innate immune defender that is short-lived but mobile and infiltrate into various tissues. We found that upon psoriasis induction, skin-resident endothelial cells are activated to produce G-CSF which activates emergency granulopoiesis in bone marrow and induces cutaneous infiltration and accumulation of neutrophil that are functionally overactive. Depletion of neutrophils or blockage of psoriasis-driven granulopoiesis by respective neutralizing antibodies results in reducing cutaneous neutrophil burden and mitigating psoriasis pathogenesis. This mechanism might be conserved in human psoriasis as confirmed by public RNA-seq database. Our findings uncovered and detailed the pathological crosstalk between skin and BM in psoriatic inflammation, proposing a potential therapeutic approach targeting cross-organ communication.

immunology↗

bioRxiv2023

Mitochondrial translation regulates terminal erythroid differentiation by maintaining iron homeostasis

A lack of the mitochondrial tRNA taurine modifications mediated by mitochondrial tRNA translation optimization 1 (Mto1) was recently shown to induce proteostress in embryonic stem cells. Since erythroid precursors actively synthesize the hemoglobin protein, we hypothesized that Mto1 dysfunctions may result in defective erythropoiesis. Hematopoietic-specific Mto1 conditional knockout (cKO) mice were embryonic lethal due to niche-independent defective terminal erythroid differentiation. Mechanistically, mitochondrial oxidative phosphorylation complex-I was severely defective in the Mto1 cKO fetal liver and this was followed by cytoplasmic iron accumulation. Overloaded cytoplasmic iron promoted heme biosynthesis and enhanced the expression of embryonic hemoglobin proteins, which induced an unfolded protein response via the IRE1-Xbp1 signaling pathway in Mto1 cKO erythroblasts. An iron chelator rescued erythroid terminal differentiation in the Mto1 cKO fetal liver in vitro. The new point of view provided by this novel non-energy-related molecular mechanism may lead to a breakthrough in mitochondrial research.

cell biology↗

bioRxiv2022

Akkermansia Muciniphila induces chronic extramedullary hematopoiesis through cooperative IL-1R and TLR signals

Bacterial infections can activate and mobilize hematopoietic stem and progenitor cells (HSPCs) from the bone marrow (BM) to spleen, which is termed as extramedullary hematopoiesis (EMH). Recent studies suggest that commensal bacteria, particularly the microbiota, regulates not only the host immune system but also hematopoietic homeostasis. However, the impact of gut microbial species on hematopoietic pathology remains largely unknown. Here we found that systemic injection of Akkermansia muciniphila (A. m.), a mucin-degrading bacterium abundantly existing in the human gut rapidly activates BM myelopoiesis, and induces a slow but long-lasting hepato-splenomegaly, characterized by the expansion and differentiation of functional HSPCs, which we termed chronic EMH. Genetic deletion of Toll-like receptor-2 and -4 (TLR2/4) partially diminished A. m.-induced chronic EMH, while additional pharmacological inhibition of the interleukin-1 receptor (IL-1R) completely alleviated splenomegaly and EMH. Our results demonstrate that cooperative IL-1R- and TLR-mediated innate immune signals regulate commensal bacteria-driven EMH, which might be relevant for certain autoimmune disorders. Article SummaryThe aim of our study is to understand how Akkermansia muciniphila (A.m.), one of the major mucin-degrading microbial species in the human gut activate the immune and hematopoietic systems in a mouse model. We found that a single injection of the A.m. membrane fraction can induce long-lasting hepatosplenomegaly with splenic EMH through cooperative IL-1R- and TLR-mediated innate immune signals.

microbiology↗

bioRxiv2021

Hematopoietic stem and progenitor cells integrate Bacteroides-derived innate immune signals to promote gut tissue repair

Bone marrow (BM)-resident hematopoietic stem and progenitor cells (HSPCs) are often activated by bacterial insults to replenish the host hemato-immune system, but how they integrate the associated tissue damage signals to initiate distal tissue repair is largely unknown. Here, we showed that acute gut inflammation expands HSPCs in the BM through GM-CSFR activation, and directs them to inflamed mesenteric lymph nodes for further differentiation into myeloid cells specialized in gut tissue repair. We also identified that this process is exclusively mediated by Bacteroides, a commensal gram-negative bacteria, that activates innate immune signaling. In contrast, chronic gut inflammation reduces HSC potential for hematopoietic reconstitution and immune response against infection. Similarly, microbial signals contribute to aging-associated HSPC expansion. These findings establish a cross-organ communication that promotes tissue regeneration, but if sustained, impairs tissue homeostasis that may be relevant to aging and chronic disorders. SummaryThe infiltrating microbiota Bacteroides upon acute colitis directed MPP migration from the BM to the MLN for their subsequent expansion and differentiation into tissue-repairing Ly6C+/G+ cells, whereas chronic colitis impairs HSC functionality similarly as aging.

pathology↗