Modificações morfológicas placentárias durante a infecção aguda por Leishmania amazonensis em modelo murino

Abstract

Leishmaniasis is considered a public health problem, and according to the World Health Organization (WHO), an estimated 350 million people are susceptible to the infection, which most frequently affects populations with socioeconomic vulnerability. In Brazil, 15,484 cases were confirmed in 2019. The immune system is directly related to defense against infectious agents. During pregnancy, this system undergoes adaptations to allow fetal tolerance and a good mother/fetus relationship, and these changes are crucial for the immunological response to intracellular parasites such as protozoa of the genus Leishmania. The placenta's primary function during pregnancy is to promote and enable fetal growth. Therefore, understanding placental morphological changes and placental efficiency in cases of acute infection by Leishmania amazonensis is relevant. Given the above, the objective of the present study was to analyze the possible influences of acute infection by Leishmania amazonensis on pregnancy in BALB/c mice, evaluating placental efficiency and its morphometric and morphological changes. Ten isogenic BALB/c mice, female and male, aged between 6 and 21 weeks, provided by the Animal Experimentation Maintenance Center (CMAE), were used. After mating between isogenic BALB/c mice, the pregnant females were randomly divided into control and infection groups. The infection group was inoculated with 105 amastigotes in the plantar pad of the left hind paw. The present study showed no change in fetal body mass (g), fetal absorptions, or the number of fetuses between the infected group and the control group, which is different from what was previously observed by other authors. However, when analyzing the mass (g) and placental efficiency, it was shown that the mass of the infected placenta decreased in the control group, and the placental efficiency of the infected group increased. A significant increase in neutrophils was identified in the placentas of the infected animals. The disorganization of the placental structures, evidenced when evaluated by microscopy, revealing modifications in the labyrinth and in the junctional zone, promoted changes in the placenta to maintain its function, with no fetal impairment when comparing the infected and control groups. The present findings contribute to disseminating knowledge about the triad of pregnancy, leishmaniasis infection, and the health of those involved, as they indicated a decrease in the mass and an increase in placental efficiency secondary to the infection. Furthermore, it revealed a difference in the total area, decidua, and junctional zone, all of which were lower in the infected group, and a significantly higher number of neutrophils in the histological image of this group than the control.