S U M M A R Y Leishmania amazonensis, an obligatory intracellular parasite, survives internalization by macrophages, but no information is available on the involvement of microglia. We have investigated microglia-protozoa interactions in mixed glial cultures infected with promastigote forms of L. amazonensis after lipopolysaccharide (LPS) or dexamethasone (DM) treatment. After 2 hr of exposure to parasites in control cultures, there was a small number of infected microglia (1%). Preincubation with LPS or DM led to 14% or 60% of microglial cells with attached parasites, respectively. DM treatment resulted in 39% of microglial cells with internalized parasites (controls or LPS-treated cells had Յ 1%). Scanning electron micrographs showed numerous filopodia in DM-treated cells, whereas these projections were rarely observed in LPS-treated or control cells. DM treatment also affected the intramicroglial survival of Leishmania . In control cultures, internalized parasites, tagged with an anti-lipophosphoglycan (anti-LPG) antibody, showed fragmented DNA [terminal deoxyribonucleotide transferase-mediated dUTP-X nick end labeling (TUNEL ϩ )] after 4 hr of interaction, but changes seemed slightly delayed in DM-treated cultures. After 12 hr, there were no LPG ϩ /TUNEL ϩ profiles in controls, whereas rare LPG ϩ profiles still persisted in DM-treated cells. Our results suggest that microglia are highly effective in the elimination of Leishmania and that the process can be effectively studied by LPG/TUNEL double labeling.
Fibrocytes are important for understanding the progression of many diseases because
they are present in areas where pathogenic lesions are generated. However, the
morphology of fibrocytes and their interactions with parasites are poorly understood.
In this study, we examined the morphology of peripheral blood fibrocytes and their
interactions with Leishmania (L.) amazonensis . Through
ultrastructural analysis, we describe the details of fibrocyte morphology and how
fibrocytes rapidly internalise Leishmania promastigotes. The
parasites differentiated into amastigotes after 2 h in phagolysosomes and the
infection was completely resolved after 72 h. Early in the infection, we found
increased nitric oxide production and large lysosomes with electron-dense material.
These factors may regulate the proliferation and death of the parasites. Because
fibrocytes are present at the infection site and are directly involved in developing
cutaneous leishmaniasis, they are targets for effective, non-toxic cell-based
therapies that control and treat leishmaniasis.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.