engleski

Immunohistopathological study of Listeria monocytogenes infection in pregnant mice

Listeria monocytogenes is a gram-positive, facultative intracellular pathogen that can cause severe food born infections in humans and animals. Pregnant women, neonates, the elderly, and debilitated or immunocompromised patients in general are predominantly affected, although the disease can also develop in normal individuals. Using a murine model of pregnancy-associated listeriosis we have done a careful analysis of the host immune response to L. monocytogenes infection. We studied the kinetics of bacterial clearance, histopathological changes in maternal and fetal tissues, as well as, cytokine/chemokine pattern during the course of L. monocytogenes infection. Pregnant BALB/c mice challanged intravenously (i.v.) showed failure of maternal anti-listerial immune response at the systemic (significantly reduced serum IFN-gamma levels) and local level (reduced expression of proinflammatory cytokines and chemokines in the liver tissue) leading to devastating necrotizing hemorrhagic hepatitis. The insufficient maternal immune response also facilitated listerial multiplication in the placenta and, ultimately, in the fetus. Placental infection was characterized by large, hemorrhagic necrosis and numerous bacterial clusters. However, the inflammatory reaction was confined to single granulocytes, while T cells and other cellular elements necessary for effective antilisterial defence were absent. During the course of infection, TNF-alpha and occasionally, IFN-gamma were transcribed in placental tissue. Increased levels of these anti-listerial cytokines were not sufficient to control bacterial growth, but may eventually contribute to spontaneous fetal loss and poor pregnancy outcome.

Listeria; pregnant mice; placental infection

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