Timothy Hand, PhD

  • Associate Professor, Department of Pediatrics
  • Mellon Scholar, Richard King Mellon Institute for Pediatric Research
  • Associate Professor, Department of Immunology
  • Member, Graduate Program in Microbiology and Immunology (PMI)

Education & Training

  • PhD, Yale University, 2009
  • Hon.B.Sc., University of Toronto, 2002

Research Interests

We now understand that humans exist as a combination of host cells and a vast consortium of bacteria, viruses and fungi, called the microbiota, that overwhelm the host both in terms of cell number and genetic information. The adaptive immune system has evolved alongside the microbiota and the cardinal feature of adaptive immunity, immune memory, may be an effort to ‘remember’ previous responses and shape subsequent host – microbial interactions. Such memory responses and protections can even be extended into children via the provision of antibodies in utero and maternal milk. Maintaining ‘friendly’ relations with the microbiota is a particular problem for the immune system because of the huge number of bacteria present that can be inflammatory depending upon the context within which they are experienced.
We are particularly interested in how the immune system deals with newly colonizing bacteria, as colonization events are dangerous for the host, since too little immune response can lead to infection but too much can contribute to autoinflammation. Our group hopes to identify the factors derived from host genetics, the environment (diet, infection etc.) and the microbiota that shape host colonization. Our hope is that this work will help us understand the root causes of diseases that are characterized by a disrupted relationship between the immune system and the microbiota, such as Necrotizing Enterocolitis, Crohn’s Disease, Colorectal cancer and Environmental Enteric Dysfunction. 
Current Projects:

  • Host-microbiome interaction during neonatal bacterial colonization 
  • Characterization of memory T cell populations from the GI tract
  • Regulation of microbiota-specific effector/memory T cells
  • Role of diet in intestinal immunity and health
  • Role of microbiota-specific T cells in the development of colon cancer


Gopalakrishna KP, Macadangdang BR, Rogers MB, Tometich JT, Firek BA, Baker R, Ji J, Burr AHP, Ma C, Good M, Morowitz MJ and Hand TW. 2019. Maternal IgA protects against the development of necrotizing enterocolitis in preterm infants. Nat Med. 25: 1110-1115. 
Chiaranunt P, Tometich JT, Ji J and Hand TW. 2018. T cell proliferation and colitis is initiated by defined intestinal microbes. J Immunol. 201: 243-250.
Hand TW*, Vujkovic-Cvijin I, Ridaura VK and Belkaid Y. 2016. Linking the microbota, chronic disease and the immune system. Trends Endocrinol Metab. 27: 831-843. *Corresponding author
Hand TW. 2016. The role of the microbiota in shaping infectious immunity. Trends Immunol. 37: 647-658.

Fonseca DM*, Hand TW*, Han S-J, Byrd AL, Gerner MY, Glatman Zaretsky A, Harrison OJ, Ortiz AM, Quinones M, Trinchieri G, Brenchley JM, Brodsky IE, Germain RN, Randolph GJ and Belkaid Y. 2015. Microbiota-dependent sequelae of acute infection compromise tissue-specific immunity. Cell. 163: 354-366. *These authors contributed equally to this work.