Th17 responses driven via PPAR γ blockade lead to faster recovery from enteroaggregative Escherichia

Washington, C., J. Bassaganya-Riera, M. Viladomiu, M. Pedragosa, R.L. Guerrant, J.K. Roche and R. Hontecillas (2012) Th17 responses driven via PPAR γ blockade lead to faster recovery from enteroaggregative Escherichia coli infection, American Association of Immunologists Annual Meeting, Boston MA

Enteroaggregative Escherichia coli (EAEC) is a recognized cause of enteric disease in diverse clinical settings. Mucosal immunity towards EAEC infections is poorly understood. To better characterize immunoregulatory mechanisms underlying EAEC infections we constructed a computational model mimicking host responses to EAEC at the gut mucosa. Preliminary model calibration efforts demonstrated remarkable fitting to experimental data. Nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) has been targeted to modulate mucosal immune responses to EAEC. Wild type and conditional knockout mice lacking PPARγ in T cells were fed protein-deficient diets at weaning and challenged with 5x10⁹cfu EAEC strain JM221. Quantitative RT-PCR data reveal that administration of GW9662, a potent PPARγ antagonist, for 7 days post infection or the deletion of PPARγ in T cells results in upregulation of pro-inflammatory cytokines including IL-6, TNF-α, and IL-1β when compared to non-treated infected animals. Histological analysis of colons divulges lower leukocyte infiltration and decreased mucosal thickness 14 days following EAEC infection after pharmacological blockade of PPARγ or deletion of PPARγ in T cells. These findings were accompanied by faster clearance of colonic EAEC in tissue-specific PPARγ null mice. In conclusion, we present a fully integrated approach to study host responses to EAEC that provides new insights on the pathogenesis and treatment of enteric infections.