Cell death mechanisms in Leishmania amazonensis triggered by methylene blue-mediated antiparasitic photodynamic therapy.
Photodiagnosis Photodyn Ther
; 23: 1-8, 2018 Sep.
Article
em En
| MEDLINE
| ID: mdl-29751117
ABSTRACT
Antiparasitic photodynamic therapy (ApPDT) is an emerging approach to manage cutaneous leishmaniasis (CL) since no side effects, contraindications and parasite resistance have been reported. In addition, methylene blue (MB) is a suitable photosensitizer to mediate ApPDT on CL. In this study we aimed to look for the best parameters to eradicate Leishmania amazonensis and investigated the cell death pathways involved in MB-mediated ApPDT. MB uptake by parasites was determined using different MB concentrations (50, 100, 250 and 500⯵M) and incubation times (10, 30 and 60â¯min). L. amazonensis promastigotes were cultured and submitted to ApPDT using different concentrations of MB (50, 100 and 250 µM) combined to a red LED emitting at 645⯱â¯10â¯nm. The pre-irradiation time was 10â¯min. Two optical powers (100â¯mW and 250â¯mW) were tested and cells were exposed to 60 and 300 s of MB-mediated ApPDT delivering energies of 6, 15, 30 and 75â¯J and fluences of 21.2, 53.1, 106.2 and 265.4â¯J/cm2, respectively. Following ApPDT, cells were prepared for flow cytometry and transmission electron microscopy to unravel the mechanisms of cell death. Our results showed the lowest MB concentration (50 µM) and the lowest optical power (100â¯mW) promoted the highest percentage of cell decrease. ApPDT caused alterations on cell membrane permeability as well depolarization of mitochondrial membrane potential. We also observed ultrastructural changes of the parasites such as cell shrinkage, intense vacuolization of the cytoplasm, enlargement of mitochondrion-kinetoplast complex, and small blebs on parasite flagella and cell membrane after MB-mediated ApPDT. Taken together, our findings ratify that ApPDT parameters play a pivotal role in cell susceptibility and suggest that apoptosis is involved in parasite death regardless MB-mediated ApPDT protocol.
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Texto completo:
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Fotoquimioterapia
/
Fármacos Fotossensibilizantes
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Leishmania
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Azul de Metileno
Tipo de estudo:
Guideline
Idioma:
En
Ano de publicação:
2018
Tipo de documento:
Article