The sandfly Lutzomyia longipalpis LL5 embryonic cell line has active Toll and Imd pathways and shows immune responses to bacteria, yeast and Leishmania.
BACKGROUND
Lutzomyia longipalpis is the main vector of visceral leishmaniasis in Latin America. Sandfly immune responses are poorly understood. In previous work we showed that these vector insects respond to bacterial infections by modulating a defensin gene expression and activate the Imd pathway in response to Leishmania infection. Aspects of innate immune pathways in insects (including mosquito vectors of human diseases) have been revealed by studying insect cell lines, and we have previously demonstrated antiviral responses in the L. longipalpis embryonic cell line LL5.


METHODS
The expression patterns of antimicrobial peptides (AMPs) and transcription factors were evaluated after silencing the repressors of the Toll pathway (cactus) and Imd pathway (caspar). AMPs and transcription factor expression patterns were also evaluated after challenge with heat-killed bacteria, heat-killed yeast, or live Leishmania.


RESULTS
These studies showed that LL5 cells have active Toll and Imd pathways, since they displayed an increased expression of AMP genes following silencing of the repressors cactus and caspar, respectively. These pathways were also activated by challenges with bacteria, yeast and Leishmania infantum chagasi.


CONCLUSIONS
We demonstrated that L. longipalpis LL5 embryonic cells respond to immune stimuli and are therefore a good model to study the immunological pathways of this important vector of leishmaniasis.
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil.
Bruno
B
Tinoco-Nunes
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil.
Erich Loza
EL
Telleria
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil.
Monique
M
da Silva-Neves
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil.
Christiane
C
Marques
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil.
Daisy Aline
DA
Azevedo-Brito
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil.
André Nóbrega
AN
Pitaluga
Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz - Fiocruz, Av. Brasil 4365, 21045-900, Rio de Janeiro, RJ, Brazil. ytraub@ioc.fiocruz.br.
Yara Maria
YM
Traub-Csekö
D000818:Animals; D001419:Bacteria / Q000276:immunology*; D002460:Cell Line; D006801:Humans; D019476:Insect Proteins / Q000235:genetics / Q000276:immunology*; D007303:Insect Vectors / Q000196:embryology / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D018314:Leishmania infantum / Q000276:immunology* / Q000502:physiology; D007898:Leishmaniasis, Visceral; D011576:Psychodidae / Q000196:embryology / Q000276:immunology* / Q000382:microbiology / Q000469:parasitology; D051193:Toll-Like Receptors / Q000235:genetics / Q000276:immunology*; D015003:Yeasts / Q000276:immunology* / Q000502:physiology
D019476:Insect Proteins; D051193:Toll-Like Receptors
Antimicrobial peptides; Embryonic cell line LL5; Imd pathway; Innate immune response; Lutzomyia longipalpis; Toll pathway