Increased Treg cells and expression of CD39/CD73 during listeriosis in aging mice

Foodborne Listeria monocytogenes (LM) is a cause of serious illness u0026 death in the elderly. Aging is associated with increased susceptibility to pathogens. We investigated the cause of this increased susceptibility of aging mice to LM infection using an oral model. Young u0026 old C57BL/6 mice were gavaged with murinized LM and T-helper (Th) cell responses were evaluated. After infection, tissues were examined for bacterial burden u0026 histology. Isolated splenocytes were analyzed for intracellular Th1/Th2 cytokine expression (TNF-α, IL-10 and IFN-γ) u0026 distribution of Treg (CD4 + CD25 h ) u0026 Th17 cells before u0026 after infection. The expression of adenosine producing enzymes, CD39/CD73, in Th cells was analyzed by FACS u0026 qRT-PCR. Old LM-infected mice lost more body-weight u0026 had a higher bacterial burden in the liver/spleen than young-infected mice. Uninfected old mice showed a higher baseline proinflammatory response when compared to young control mice. After infection, the proinflammatory cytokine, IFN-g, was higher in young mice as compared to old mice. An increase in Th-17 cells was observed in the older mice before u0026 after infection. Increased levels of IL-10 u0026 Treg cells were observed in older mice after infection. Higher expression of CD39/CD73 was observed in the Th cells of the older mice u0026 the Treg expression of CD39 doubled after infection, suggesting increased production of adenosine, an anti-inflammatory mediator. Increased LM infection in aging mice is associated with reduced IFN-g response u0026 increased anti-inflammatory responses from Treg cells with high expression of CD39 in splenocytes. Increased accumulation of splenic Th17 cells in LM-infected old mice can further contribute to increased inflammation leading to LM pathogenesis.