Fetal and neonatal exposure to the mycotoxin zearalenone induces phenotypic alterations in adult rat mammary gland.

Zearalenone is a mycotoxin that is widespread in cereal food. We questioned whether this mycotoxin, administered during known critical exposure periods such as the fetal period and the first days of life, at doses compatible with mean daily intake in humans, could have an effect on mammary gland development in rodents. Wistar female rats were exposed to zearalenone (0.2 µg/kg to 5mg/kg) during the last 14 days of fetal life and the first 5 post-natal days (PND). The mammary tissue was examined for development and maturation by morphologic analyses and immunochemistry. At PND 30, the mean length of terminal buds was significantly enhanced in all of the zearalenone-exposed females (p<0.05). The mammary tissue, as evaluated by scoring of tissue slides, was significantly more differentiated in the 1mg/kg treated group than in controls (p<0.05). At PND 180, mammary tissue was more differentiated in all of the zearalenone treated groups (p<0.05). At six months, 4 of 18 females exposed to 5mg/kg of zearalenone presented mammary hyperplasia lesions. The induction of phenotypic alterations by zearalenone administered in utero and in the neonatal period at doses as low as 0.2 µg/kg suggests that zearalenone could contribute to the induction of breast endocrine disorders.

Mammary transmission of caprine arthritis encephalitis virus: a 3D model for in vitro study.

Transmission of Caprine Arthritis Encephalitis virus (CAEV) from the mother to offspring is principally mediated by infected cells from colostrum and milk. The infection of the dam is often sub-clinical, and results in increased cellularity of milk, sometimes exacerbated by bacterial co-infections. Although monocytes are the major viral host cells, several other cell types, including epithelial mammary cells, fibroblasts and endothelial cells show low levels of in vivo infection. In vitro, however, all phenotypes of mammary gland cells are individually highly sensitive to CAEV infection. This suggests that local mechanisms act to control viral expression. Our goal is to analyse the mechanisms regulating local virus infection, including the physiological status of the mammary gland and bacterial co-infections. In this work, we present the development of a model for the in vitro reconstitution of mammary gland tissue using 3D cultures in Matrigel. Mononuclear cells from the blood are added to the 3D cultures in vitro. In these experimental conditions, the mammary cells spontaneously organize into mammospheres. Blood leucocytes migrate into the culture gel, and localize particularly at the periphery of the mammospheres. Mammospheres were susceptible to infection in vitro by CAEV, as shown by a cytopathic effect and expression of late CAEV antigen p30. This model will allow the in vitro study of virus expression, transfer of infection to mammary gland cells and interactions between the mammary gland cells, infected monocytes and immunocompetent cells. It will allow the study of mechanisms participating in the control of passage of pathogens into milk, according to the physiological and CAEV-infection status of the animal, microenvironment and the presence of bacterial co-infections.

In vitro infection of aortic endothelial cells by caprine arthritis encephalitis virus enhances in vitro transmigration of peripheral blood leukocytes and modulates their phenotypic expression.

Infection of goats by caprine arthritis-encephalitis virus (CAEV) provides a convenient example of the infiltration of various tissues by leukocytes following a natural lentiviral infection. This event is important in determining organ susceptibility and local immunity. Caprine vascular endothelial cells are susceptible to infection by CAEV in vitro, so we have investigated the consequences of this infection on the transmigration of uninfected leukocytes in an in vitro model. After in vitro infection by CAEV or stimulation by TNFalpha, the endothelial cells allowed the passage of tenfold more leukocytes from uninfected donors than did the uninfected endothelial cells. The transmigrating leukocytes were enriched in CD8+ lymphocytes, and the leukocytes appeared to have been activated during transmigration, as demonstrated by their expression of IL2R, MHC class II antigens and gamma-delta T-lymphocyte markers. CD4+, CD8+ and B-lymphocytes all proliferated in culture after transmigration. These results suggest that any possible infection or specific stimulation of endothelia in an infected animal could profoundly influence the choice of target organs and could activate the cells involved in local mucosal immune responses.