Intestinal microbiota regulates tryptophan metabolism following oral infection with Toxoplasma gondii
Liliane M Dos Santos1, Alessandra G Commodaro2, Alicia R R Vasquez1
1Departamento de Bioquímica e Imunologia, Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, Brazil.
Introduction:
The intestinal microbiota plays an important role in modulating host immune responses. Oral Toxoplasma gondii infection can promote intestinal inflammation in certain mice strains. The IDO-AhR axis may control tryptophan (Trp) metabolism constituting an important immune regulatory mechanism in inflammatory settings.
Aims:
In the present study, we investigated the role of the intestinal microbiota on Trp metabolism during oral infection with T gondii.
Methods And Results:
Mice were treated with antibiotics for four weeks and then infected with T gondii by gavage. Histopathology and immune responses were evaluated 8 days after infection. We found that depletion of intestinal microbiota by antibiotics contributed to resistance against T gondii infection and led to reduced expression of AhR on dendritic and Treg cells. Mice depleted of Gram-negative bacteria presented higher levels of systemic Trp, downregulation of AhR expression and increased resistance to infection whereas depletion of Gram-positive bacteria did not affect susceptibility or expression of AhR on immune cells.
Conclusion:
Our findings indicate that the intestinal microbiota can control Trp availability and provide a link between the AhR pathway and host-microbiota interaction in acute infection with T gondii.
