Pten gene deletion in intestinal epithelial cells enhances susceptibility to Salmonella Typhimurium infection in mice

Although phosphatase and tensin homolog (PTEN) is typically considered a tumor-suppressor gene, it was recently suggested that PTEN regulates TLR5-induced immune and inflammatory responses in intestinal epithelial cells (IECs), suggesting an immunomodulatory function of PTEN in the gut. However, this alternative function of PTEN has not yet been evaluated in an in vivo context of protection against enteropathogenic bacteria. To address this, we utilized IEC-restricted Pten knockout (Pten(Delta IEC/Delta IEC)) and fittermate Pten(+/+) mice. These mice were subjected to the streptomycin-pretreated mouse model of Salmonella infection, and subsequently given an oral gavage of a low inoculum (2 x 10(4) CFU) of Salmonella enterica serovar Typhimurium (S. Typhimuritmi). This bacterial infection not only increased the mortality of Pten(Delta IEC/Delta IEC) mice compared to Pten(+/+) mice, but also induced deleterious gastrointestinal inflammation in Pten(Delta IEC/Delta IEC) mice manifested by massive histological damage to the intestinal mucosa. S. Typhimurium infection up regulated pro-inflammatory cytokine production in the intestine of Pten(Delta IEC/Delta IEC) mice compared to controls. Furthermore, bacterial loads were greatly increased in the liver, mesenteric lymph node, and spleen of Pten(Delta IEC/Delta IEC) mice compared to controls. Together, these results suggest that IEC-restricted Pten deficiency renders the host greatly susceptible to Salmonella infection and support an immuneregulatory role of PTEN in the gut.