Competition for essential nutrients and/or release of toxic metabolites are mechanisms highly conserved in both bacteria and higher organisms as innate defense systems from external pathogens. One such mechanism is based on the activation of indoleamine 2,3-dioxygenase (IDO), an enzyme that catalyzes the catabolism of the essential amino acid tryptophan (rev. in 1). By depleting tryptophan, IDO...

Purpose: Cyclooxygenase-2 (COX-2) and its metabolite, PGE2 affect multiple tumorigenesis, including angiogenesis, invasion, and tumor-induced immune suppression. Their overexpression is association with impaired immune cell function in many tumors. Indoleamine 2,3-dioxygenase (IDO) is an emerging immuno-regulatory enzyme that can catalyze the initial rate-limiting step in tryptophan catabolism,...

Materials and methods Patients (n = 16) with septic shock had IDO activity assessed (expressed as the ratio of Kyn to Trp) and the severity of their hypotension determined (expressed by inotrope requirement) during the course of illness. Normal and blood pressure-matched controls were also studied. Septic shock was induced in wild type and IDO-/mice, and the effect of 1-methyl-tryptophan (1 MT,...

The exclusive ability of dendritic cells (DCs) to stimulate primary and secondary immune responses favors the use of antigen-loaded human monocyte-derived DCs (MoDCs) in vaccinations against tumors. Previous studies demonstrated that PGE(2) is fundamental during MoDC maturation to facilitate migration toward lymph node-derived chemokines. A recent study challenged the use of PGE(2), as PGE(2) i...

Dendritic cell-derived indoleamine 2,3-dioxygenase (IDO) suppresses naive T cell proliferation and induces their apoptosis by catalyzing tryptophan, and hence is essential for the maintenance of peripheral tolerance. However, it is not known whether memory T cells are subject to the regulation by IDO-mediated tryptophan catabolism, as memory T cells respond more rapidly and vigorously than thei...

OBJECTIVE In this study, we sought to better understand the immunoregulatory function of stem cells derived from human exfoliated deciduous teeth (SHED). We studied the role of the interferon gamma (IFN-γ)-indoleamine 2,3-dioxygenase (IDO)-axis in immunoregulation of SHED compared to bone marrow derived mesenchymal stem cells (BMMSCs) under the same conditions. MATERIALS AND METHODS In this c...

Initially, indoleamine-2,3-dioxygenase (IDO) has been introduced as a bactericidal effector mechanism and has been linked to T-cell immunosuppression and tolerance. In recent years, evidence has been accumulated that IDO also plays an important role during viral infections including HIV, influenza, and hepatitis B and C. Moreover, novel aspects about the role of IDO in bacterial infections and ...

Uropathogenic Escherichia coli (UPEC) are the chief cause of urinary tract infections. Although neutrophilic inflammation is a hallmark of disease, previous data indicate that UPEC promotes local dampening of host innate immune responses. Here, we show that UPEC attenuates innate responses to epithelial infection by inducing expression of indoleamine 2,3-dioxygenase (IDO), a host enzyme with pr...

In the present study, we examined the role of indoleamine 2,3-dioxygenase (IDO) in the development of CCl4-induced hepatic fibrosis. The liver fibrosis induced by repetitive administration with CCl4 was aggravated in IDO-KO mice compared to WT mice. In IDO-KO mice treated with CCl4, the number of several inflammatory cells and the expression of pro-inflammatory cytokines increased in the liver....

Tryptophan catabolism via the kynurenine pathway is dependent on the enzyme Indoleamine 2,3-dioxygenase (IDO). Expression of IDO is upregulated in a number of inflammatory settings such as wounding and infection, and the resulting local tryptophan depletion may inhibit the replication of intracellular pathogens. Indo gene expression is upregulated in the gut during chronic infection with the mo...