Xin Li, Ph.D.

Xin Li, Ph.D., is an Assistant Professor (tenure-track) in the Department of Pediatrics at UT Southwestern Medical Center, with a secondary appointment in the Department of Immunology. His research interests lie in studying host-microbiota interactions in health and disease. Using innovative techniques in microbiology and immunology, and multiple model organisms (bacteria, fungi, drosophila, mice, and humans), his research aims to investigate the fundamental mechanisms by which gut commensal bacteria and fungi regulate local and systemic inflammatory immune responses.

For his Ph.D., under the mentorship of Dr. Wendy Watford at the University of Georgia, Dr. Li studied the role of Tpl2, a host serine-threonine kinase, in modulating T regulatory and Th17 cell function, identifying a potential therapeutic target for autoimmune disorders. During his postdoctoral training at Weill Cornell Medical College, mentored by Dr. Iliyan Iliev and co-mentored by Dr. David Artis, he focused on the impact of gut commensal fungi on host immune responses. His recent work revealed that fungal sensing by tissue-resident CX3CR1+ mononuclear cells in the gut can influence distal allergic airway disease, with specific immune cells transmitting signals to the lungs, initiating early mechanistic studies for gut-lung immune crosstalk (Li et al., Cell Host and Microbe, 2018; Leonardi, Li et al., Science, 2018). In a recent study (Li et al., Nature, 2022), Dr. Li demonstrated the significance of microbial strain diversity in driving inflammatory immunity. By analyzing diverse fungal strains and their fungal factors, he found that high levels of the fungal candidalysin (a pore-forming toxin) were associated with more severe ulcerative colitis. Replicating these results in murine colitis models, Dr. Li identified a key pore-forming toxin (candidalysin) that mediates niche-specific inflammatory immunity. These findings highlight the importance of personalized approaches in developing microbiome-based therapeutics. In 2023, he joined the faculty at UT Southwestern in the Departments of Pediatrics and Immunology. Dr. Li and his team continue their work studying host-microbe interactions and tissue immunity using multiple model organisms.

His new research directions involve:

i) Identifying novel host factors involved in bacterial and fungal sensing to regulate inflammatory diseases.
ii) Identifying new microbial factors involved in bacterial and fungal sensing to regulate inflammatory diseases. These factors may include pore-forming toxins and other toxins.
iii) Identifying how microbe sensing of host-derived factors in the gut controls microbial commensalism and pathogenicity.
iv) Utilizing fungi as a model system, genetic engineering of microbial effectors to understand how a microbe dictates protective immunity, and pathogenic immunity at tissue barriers.

Contact: xin.li@utsouthwestern.edu