Chemokine Expression Patterns Differ within Anatomically Distinct Regions of the Genital Tract duringChlamydia trachomatisInfection

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Abstract
Untreated infections with Chlamydia trachomatis commonly result in ascending infection to fallopian tubes and subsequent immune-mediated tubal pathology in females. The proposed immune-mediated injury may be associated with the increased recruitment of CD4 cells to the upper genital tract (GT) (oviducts) in comparison to the lower GT (cervix) during infection, as shown in animal models. To understand the mechanisms responsible for this biased recruitment of CD4 cells within the GT, we characterized chemokine expression patterns in the upper and lower GTs in mice during infection with the murine pneumonitis biovar of Chlamydia trachomatis. Enzyme-linked immunosorbent assays of supernatants from GT homogenates revealed that the levels of the Th1-associated chemokines CXCL9 (monokine induced by gamma interferon), CXCL10 (interferon-inducible protein 10), and CCL5 (RANTES) were significantly higher in the upper GT than in the lower GT after infection, while the CCL3 (macrophage inflammatory protein 1α) level was not increased. In contrast, the level of chemokine CCL11 (eotaxin) was significantly elevated in the lower GT later in the course of infection. Increased levels of mRNA confirmed the selective differences in chemokine expression within the upper and lower GTs. The increased levels of Th1-inducible chemokines in the upper GT were not due to differences in the magnitude of infection or progesterone pretreatment. These data demonstrate that the upper and lower regions of the GT respond differently to Chlamydia infection.