Zinc (Zn) deficiency has emerged as a growing public health problem. In fact, an estimated 17% of the global
population is deficient. Animal studies have demonstrated that even marginal zinc deprivation leads to
significantly impairs physiological functions. This is especially true in the gut where zinc is required to maintain
intestinal homeostasis. Zn deficiency-mediated loss of intestinal homeostasis and microbial dysbiosis have
recently been proposed as major mechanistic pathways for the development and severity of inflammatory bowel
disease (IBD). Specifically, Zn deficiency is common in patients with IBD with a prevalence ranging from 15% to
40%, likely due to diet deficits and increased intestinal loss. In addition, a common genetic variant of the Zn
transporter ZIP8 (rs13107325; A391T) has been associated with an increased risk of Crohn’s disease. In the
context of gastrointestinal health, it is also notable that zinc is also an essential nutrient for bacteria. As such,
commensals must compete for and scavenge zinc from their host, which likely further effects the host’s ability to
acquire adequate levels of zinc. Bacteria utilize numerous strategies to acquire metal, such as the secretion of
small molecules known as metallophores (i.e., siderophores and zincophores). Overgrowth of pathobionts, which
express high levels of metallophores, is hypothesized to be one mechanism by which the microbiota contributes
to IBD pathogenesis. In this application, we propose a new paradigm in which bacterial metallophore production
is a key mechanistic pathway leading to accelerated IBD disease severity/inflammation. Specifically, we
hypothesize that IBD disease status is associated with a unique subset of microbial metallophores and further
hypothesize that IBD-associated metallophores exacerbate disease severity. Four key findings support this
hypothesis: First, humans with the A391T allele have and increased prevalence of IBD and have significantly
altered intestinal microbial communities. Second, Zip8 393T-KI mice have increased susceptibility to chemically
induced colitis. Third, microbial metallophores are associated with the development of adherent-invasive
Escherichia coli (AIEC)-mediated colitis. Fourth, a novel class of zinc transporters (zincophores) are produced
by a wide-range of known gastrointestinal bacterial species many of which are over-represented in IBD dysbiosis.
To test our hypothesis that bacterial zincophore production is a key mechanistic pathway leading to increased
IBD disease severity, we propose three research Aims: Aim 1 will establish cross-talk between host genetics,
gut microbial composition, bacterial metallophores, and dietary Zn levels as a link to IBD severity. Aim 2 will
determine and characterize the effects of bacterial metallophores on intestinal epithelial health. Aim 3 will seek
to validate the association of bacterial metallophores with IBD disease using a well characterized IBD biobank.
