Title

Involvement of gonadal steroids and gamma interferon in sex differences in response to blood-stage malaria infection

Document Type

Journal Article

Publication Date

6-1-2006

Journal

Infection and Immunity

Volume

74

Issue

6

DOI

10.1128/IAI.00008-06

Abstract

To examine the hormonal and immunological mechanisms that mediate sex differences in susceptibility to malaria infection, intact and gonadectomized (gdx) C57BL/6 mice were inoculated with Plasmodium chabaudi AS-infected erythrocytes, and the responses to infection were monitored. In addition to reduced mortality, intact females recovered from infection-induced weigh loss and anemia faster than intact males. Expression microarrays and real-time reverse transcription-PCR revealed that gonadally intact females exhibited higher expression of interleukin-10 (IL-10), IL-15Rα, IL-12Rβ, Gadd45γ, gamma interferon (IFN-γ), CCL3, CXCL10, CCR5, and several IFN-inducible genes in white blood cells and produced more IFN-γ than did intact males and gdx females, with these differences being most pronounced during peak parasitemia. Intact females also had higher anti-P. chabaudi immunoglobulin G (IgG) and IgG1 responses than either intact males or gdx females. To further examine the effector mechanisms mediating sex differences in response P. chabaudi infection, responses to infection were compared among male and female wild-type (WT), T-cell-deficient (TCRβδ-/-), B-cell-deflcient (μMT), combined T- and B-cell-deficient (RAG1), and IFN-γ knockout (IFN-γ-/-) mice. Males were 3.5 times more likely to die from malaria infection than females, with these differences being most pronounced among TCRβδ-/-, μMT, and RAG1 mice. Male mice also exhibited more severe weight loss, anemia, and hypothermia, and higher peak parasitemia than females during infection, with WT, RAG1, TCRβδ-/-, and μMT mice exhibiting the most pronounced sexual dimorphism. The absence of IFN-γ reduced the sex difference in mortality and was more detrimental to females than males. These data suggest that differential transcription and translation of IFN-γ, that is influenced by estrogens, may mediate sex differences in response to malaria. Copyright © 2006, American Society for Microbiology. All Rights Reserved.

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