Open AccessToll‐like receptor 4 is needed to restrict the invasion of Escherichia coli P4 into mammary gland epithelial cells in a murine model of acute mastitis
Author(s) -
Gonen Erez,
VallonEberhard Alexandra,
Elazar Sharon,
Harmelin Alon,
Brenner Ori,
Rosenshine Ilan,
Jung Steffen,
Shpigel Nahum Y.
Publication year - 2007
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2007.00999.x
Subject(s) - tlr4 , biology , adoptive cell transfer , microbiology and biotechnology , lipopolysaccharide , inflammation , mastitis , toll like receptor , immunology , mammary gland , innate immune system , escherichia coli , immune system , gene , t cell , cancer , genetics , breast cancer , biochemistry
Summary Mastitis, an inflammatory response of the mammary tissue to invading pathogenic bacteria, is a common disease in breast‐feeding women and dairy animals. Escherichia coli is a leading cause of mastitis in dairy animals. During the course of the disease the host mounts a strong inflammatory response, but specific bacterial virulence factors have not yet been identified. Here we report the use of a murine mastitis model to investigate the innate inflammatory reaction of the mammary gland. We show that lipopolysaccharide (LPS) infusion induces mastitis in wild‐type mice (C3H/HeN), but not in mice expressing mutated Toll‐like receptor 4 (TLR4) (C3H/HeJ). The wild‐type phenotype was restored by adoptive transfer of TLR4‐expressing macrophages into the alveolar milk space of C3H/HeJ mice. In contrast to the LPS treatment, infection with E. coli P4 (ECP4) resulted in inflammation even in the absence of LPS/TLR4 signalling, indicating that additional factors play a role in the pathogenesis of the intact bacteria. Furthermore, in the absence of functional TLR4 the infecting ECP4 invade the epithelial cells with high efficiency, forming intracellular microcolonies. However, adoptive transfer with TLR4‐expressing macrophages drastically reduced the epithelial invasion. Taken together, these results indicate that ECP4 has an invasive potential, which is restricted by alveolar macrophages in response to the LPS/TLR4 signalling.