Related Experiment Video
Updated: Jun 9, 2026
08:31
Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition
Published on: October 3, 2018
A potential role for indoleamine 2,3-dioxygenase (IDO) in Rhodococcus equi infection.
M C Heller1, C P Drew, K A Jackson
1Dept. of Veterinary Medicine and Epidemiology, University of California Davis, One Shields Ave., Davis, CA 95616, USA. mcheller@ucdavis.edu
Veterinary Immunology and Immunopathology
|August 27, 2010
Summary
Indoleamine 2,3-dioxygenase (IDO) dampens inflammation during Rhodococcus equi infection by reducing regulatory T cells. IDO deficiency in mice led to increased liver inflammation and decreased TGFβ and FOXP3 expression.
Area of Science:
- Immunology
- Microbiology
- Pathogenesis
Background:
- Rhodococcus equi is a pathogen affecting foals and immunocompromised individuals.
- The bacterium infects macrophages and dendritic cells (DC).
- Indoleamine 2,3-dioxygenase (IDO) is upregulated during R. equi infection.
Purpose of the Study:
- To assess the role of IDO in R. equi infection.
- To investigate the immune-regulatory function of IDO in R. equi pathogenesis.
Main Methods:
- Assessed R. equi growth requirement for tryptophan.
- Inhibited IDO pharmacologically in equine macrophages.
- Infected IDO-deficient and control mice with R. equi.
- Analyzed bacterial counts, inflammation scores, and gene expression (IFNγ, TNFα, IL-4, IL-6, IL-10, IL-12, IL-23, FoxP3, TGFβ).
Main Results:
- R. equi growth did not require tryptophan; IDO inhibition did not affect intracellular proliferation.
- IDO-deficient mice showed no difference in bacterial load but had higher liver inflammation at 6 days post-infection.
- IDO deficiency led to decreased TGFβ and FOXP3 expression and fewer FOXP3+ regulatory T cells in the liver.
Conclusions:
- IDO expression by macrophages and DC dampens the inflammatory response to R. equi infection in mice.
- IDO plays a role in immune regulation during R. equi infection, potentially by influencing regulatory T cell populations.
Related Concept Videos
01:28Gene Regulation in Microbial Communities: Quorum Sensing
Quorum sensing is a mechanism of bacterial communication that enables coordinated gene expression in response to changes in population density. This facilitates collective behaviors that enhance survival, resource acquisition, and ecological adaptation. This process relies on small signaling molecules called autoinducers that accumulate as bacterial populations grow. When a critical threshold concentration of autoinducers is reached, bacterial cells collectively modify gene expression,...
02:32Exon Recombination
The evolution of new genes is critical for speciation. Exon recombination, also known as exon shuffling or domain shuffling, is an important means of new gene formation. It is observed across vertebrates, invertebrates, and in some plants such as potatoes and sunflowers. During exon recombination, exons from the same or different genes recombine and produce new exon-intron combinations, which might evolve into new genes.
Exon shuffling follows “splice frame rules.” Each exon has three reading...
Exon shuffling follows “splice frame rules.” Each exon has three reading...
01:31Regulation of the Unfolded Protein Response
Inositol-requiring kinase one or IRE1 is the most conserved eukaryotic unfolded protein response (UPR) receptor. It is a type I transmembrane protein kinase receptor with a distinctive site-specific RNase activity. As the binding mechanics of the misfolded proteins with the N-terminal domain of IRE-1 are unclear, three binding models — direct, indirect, and allosteric -- are proposed for receptor activation. Nevertheless, it is known that once a misfolded protein associates with IRE1, it...
01:30Bacterial Signaling
Bacterial signaling can occur within bacteria (intracellular) or between bacteria (intercellular). At times, a group of bacteria behaves like a community. To achieve this, they engage in quorum sensing, the perception of higher cell density that causes changes in gene expression. Quorum sensing involves both extracellular and intracellular signaling. The signaling cascade starts with a molecule called an autoinducer (AI). Individual bacteria produce AIs that move out of the bacterial cell...
01:28Regulation of Bacterial Virulence
Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
01:26Bacterial Meningitis II: Pathophysiology
Bacterial meningitis typically begins when pathogens such as Neisseria meningitidis and Streptococcus pneumoniae colonize the nasopharynx and invade the bloodstream. This process is facilitated by bacterial virulence factors, such as polysaccharide capsules, which resist phagocytosis and complement-mediated killing. Less commonly, bacteria reach the central nervous system via contiguous spread from infections like otitis media or sinusitis, through congenital or acquired dural defects, or...