Esen Sefik, PhD

Dr. Esen Sefik is an assistant professor in the Department of Immunobiology at Yale University School of Medicine. She received her B.S. from Yale College and her PhD from Harvard University.

During her doctoral training, she explored host-microbe interactions from a tolerogenic perspective, focusing on maintaining tissue-level homeostasis. To investigate how microbiota aid the maturation of the host immune system, she conducted a pioneering large-scale screen. This involved colonizing germ-free mice with individual bacterial strains. Through focused analysis, she uncovered microbiota-dependent transcriptional control mechanisms affecting Foxp3+ regulatory T cells and IL17-producing T cells. Her findings challenged earlier research on Rorγ and Foxp3, suggesting a collaborative rather than competitive regulation, facilitated by microbiota.

During her postdoctoral training, Dr. Sefik used humanized mice to model human-microbe interactions in chronic infectious and inflammatory diseases. She modeled severe COVID-19 in humanized mice, which exhibited persistent lung pathology similar to that in human patients. Mechanistic studies of this model revealed a cascade of events highlighting the unique contributions of human immune cells, particularly macrophages, to lung pathology. These mice also proved to be excellent models for studying fibrotic diseases with microbial etiology.

Various immune and non-immune cells interact to form a coherent system in tissues. Dr. Sefik is interest in how this system fails during chronic infections. Her work emphasizes the delicate balance maintained by host-microbe interactions, a balance critical for immune system development yet vulnerable to the ravages of chronic inflammatory stimuli. Her goal is to continue elucidating these complex biological mechanisms, contributing to our collective knowledge and the potential for therapeutic advancements.