Kazuki Nagashima (永島 一樹) grew up in Tokyo, Japan. His childhood experience with food allergies drove his interest in the gut immune system and motivated him to go to medical school at the University of Tokyo, where he was inspired by a Clostridium difficile infection caused by dysbiosis of the microbiota.  He was fascinated by the mysterious intestinal ecosystem in which the immune system permits diet and microbiome and eliminates pathogens.

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To learn state-of-art immunology, he started his Ph.D. training in Dr. Hiroshi Takayanagi’s lab at the University of Tokyo. He addressed a longstanding question in the host-microbe interaction – how antigens of the microbiome are recognized by the host's immune system and initiate an IgA response. He discovered a previously uncharacterized mesenchymal cell subset that induces epithelial microfold (M) cells and promotes the antigen-specific IgA response.

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To explore the host-microbiome interaction from a microbial perspective, he joined Michael Fischbach Lab at Stanford University as a postdoc. He developed a technology to understand the “physiological” gut ecosystem at high resolution. He colonized germ-free mice with a complex defined gut community (>100 strains) and profiled T cell responses to each strain individually. His work provides a framework to logically design microbiome therapeutics for systemic disorders.