Immunological interactions between 2 common pathogens, Th1-inducing protozoan Toxoplasma gondii and the Th2-inducing helminth Fasciola hepatica

Miller, Catherine M.D., Smith, Nicholas C., Ikin, Rowan J., Boulter, Nicola R., Dalton, John P., and Donnelly, Shelia (2009) Immunological interactions between 2 common pathogens, Th1-inducing protozoan Toxoplasma gondii and the Th2-inducing helminth Fasciola hepatica. PLoS ONE, 4 (5). e5692. pp. 1-10.

[img]
Preview
PDF (Published Version) - Published Version
Available under License Creative Commons Attribution.

Download (568kB)
View at Publisher Website: http://dx.doi.org/10.1371/journal.pone.0...
 
32
86


Abstract

Background: The nature of the immune response to infection is dependent on the type of infecting organism. Intracellular organisms such as Toxoplasma gondii stimulate a Th1-driven response associated with production of IL-12, IFN-γ, nitric oxide and IgG2a antibodies and classical activation of macrophages. In contrast, extracellular helminths such as Fasciola hepatica induce Th2 responses characterised by the production of IL-4, IL-5, IL-10 and IgG1 antibodies and alternative activation of macrophages. As co-infections with these types of parasites commonly exist in the field it is relevant to examine how the various facets of the immune responses induced by each may influence or counter-regulate that of the other.

Principal Findings: Regardless, of whether F. hepatica infection preceded or succeeded T. gondii infection, there was little impact on the production of the Th1 cytokines IL-12, IFN-γ or on the development of classically-activated macrophages induced by T. gondii. By contrast, the production of helminth-specific Th2 cytokines, such as IL-4 and IL-5, was suppressed by infection with T. gondii. Additionally, the recruitment and alternative activation of macrophages by F. hepatica was blocked or reversed by subsequent infection with T. gondii. The clinical symptoms of toxoplasmosis and the survival rate of infected mice were not significantly altered by the helminth.

Conclusions: Despite previous studies showing that F. hepatica suppressed the classical activation of macrophages and the Th1-driven responses of mice to bystander microbial infection, as well as reduced their ability to reject these, here we found that the potent immune responses to T. gondii were capable of suppressing the responses to helminth infection. Clearly, the outcome of particular infections in polyparasitoses depends on the means and potency by which each pathogen controls the immune response.

Item ID: 26389
Item Type: Article (Research - C1)
ISSN: 1932-6203
Additional Information:

© 2009 Miller et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Date Deposited: 22 May 2013 02:35
FoR Codes: 07 AGRICULTURAL AND VETERINARY SCIENCES > 0707 Veterinary Sciences > 070708 Veterinary Parasitology @ 20%
11 MEDICAL AND HEALTH SCIENCES > 1107 Immunology > 110707 Innate Immunity @ 40%
11 MEDICAL AND HEALTH SCIENCES > 1108 Medical Microbiology > 110803 Medical Parasitology @ 40%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970106 Expanding Knowledge in the Biological Sciences @ 50%
92 HEALTH > 9201 Clinical Health (Organs, Diseases and Abnormal Conditions) > 920109 Infectious Diseases @ 50%
Downloads: Total: 86
Last 12 Months: 27
More Statistics

Actions (Repository Staff Only)

Item Control Page Item Control Page