Theodore Steiner

 
Prospective Graduate Students / Postdocs

This faculty member is currently not actively recruiting graduate students or Postdoctoral Fellows, but might consider co-supervision together with another faculty member.

Professor

Research Classification

Cell Signaling and Infectious and Immune Diseases
Cell Therapy of Infectious and Immune Diseases
Gastrointestinal Pathologies
Infectious Diseases

Research Interests

intestinal immunology
Innate immunity
gastrointestinal infections

Relevant Degree Programs

 

Biography

The human gut is a very complex system that affects many areas of health. For the gut to work normally, there must be coordination between the immune system, nervous system, and multiple different cell types that line the gut and help it to process and absorb food while fighting infections. The gut also carries a huge number of microbes that play important roles in maintaining its functions. My work focuses on the way that the intestinal immune system functions to fight infections while maintaining normal relationships with the "good" bacteria that normally live in the gut.

Research Methodology

mouse colitis models
Flow cytometry
Intestinal microbiome

Graduate Student Supervision

Doctoral Student Supervision (Jan 2008 - May 2019)
Immune regulation of autoinflammation caused by cellular stress (2015)

During chronic inflammation and tissue injuries, various danger-associated molecules can be released and are able to potentiate inflammation and T cell responses. Among the many possible danger signals, I focused on studying high concentrations of extracellular ATP since it has been implicated in a variety of autoinflammatory diseases. ATP activates the inflammasome in macrophages, stimulates dendritic cell (DC) maturation, and inhibits regulatory T cell (Treg) function. However, how ATP regulates Toll-like receptor (TLR) responses in intestinal epithelial cells (IECs), which represent the front line of enteric defense, remains unclear. Therefore, I examined how ATP modulates TLR responses in IECs and found that it enhanced the response of IECs to a TLR1/2 ligand Pam₃CSK₄ primarily through the P2X7 purinergic receptor, leading to increased DC maturation and antigen-specific T cell proliferation. Furthermore, intra-rectal delivery of ATP lowered the activation threshold of epithelial cells to endogenous TLR ligands, making IECs more prone to immune activation. Since ATP is an important molecule that can potentiate inflammatory responses, the second aim of the study was to investigate if Tregs, including Foxp3+ Tregs and IL-10 producing Tr1 cells, can regulate ATP induced inflammasome activation and IL-1β production. I found that Tr1 cells inhibited the production of Il1b mRNA, inflammasome-mediated activation of caspase-1, and secretion of mature IL-1β, in an IL-10 dependent manner. Surprisingly, Foxp3+ Tregs, despite the production of IL-10, failed to inhibit IL-1β production. The important role of IL-10 in regulating inflammasome activation was further illustrated in the monosodium urate induced peritonitis model, where IL-10R-deficient mice had an increased influx of peritoneal neutrophils compared to wild type mice. Moreover, IL-1β production from macrophages derived from Nlrp3A350V knock-in mice, which carry a mutation found in cryopyrin associated periodic syndrome patients, was suppressed by Tr1 cells, but not Foxp3+ Tregs. Using an adoptive transfer model, I found Tr1 cells can protect against weight loss in mice expressing a gain-of-function mutation in NLRP3. Collectively, these data demonstrated the complex regulation of host response to cellular stress signal ATP, and that IL-10 producing Tr1 cells may have unique therapeutic effects in controlling ATP-mediated inflammasome activation via IL-10-mediated suppression.

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Publications

Current Students & Alumni

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