Estradiol required for immune response to pathogens

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If the Stealth bacteria hypothesis in autoimmune disease is correct this could explain the prevalance in women as they age.Lynn

Estradiol Is Required for a Proper Immune Response to Bacterial and Viral Pathogens in the Female Brain 1

Geneviève Soucy*, Guy Boivin, Fernand Labrie* and Serge Rivest2,*

* Laboratory of Molecular Endocrinology and

Infectious Diseases, Centre Hospitalier de l'Université Laval Research

Center and Department of Anatomy and Physiology, Université Laval,

Québec City, Québec, Canada

Although the neuroprotective effects of estrogens are well recognized, the exact mechanisms involved in the ability of these sex steroids to protect the cerebral tissue still remain unclear. We tested in our study the hypothesis that estradiol (E2) modulates the innate immune response and expression of genes encoding proteins that a provide survival signal to neurons during infection. Mice received a single systemic or cerebral injection of LPS to trigger a robust but transient inflammatory reaction in the brain. The endotoxin increased transcriptional activation of genes encoding TLR2, TNF-, and IL-12 in microglial cells. Expression of these transcripts was largely inhibited in the brain of ovariectomized mice at time 24 h postchallenge. E2 replacement therapy totally rescued the ability of the endotoxin to trigger microglial cells and these permissive effects of E2 are mediated via the estrogen receptor (ER). Indeed, ER-deficient mice exhibited an inappropriate reaction to LPS when compared with ER-deficient and wild-type mice. This defective innate immune response was also associated with a widespread viral replication and neurodegeneration in ovariectomized mice inoculated intranasally with HSV-2. These data provide evidence that interaction of E2 with their nuclear ER plays a critical role in the control of cytokines involved in the transfer from the innate to adaptive immunity. This transfer is deviant in mice lacking E2, which allows pathogens to hide from immune surveillance and exacerbates neuronal damages during viral encephalitis.