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PHOTODYNAMIC INACTIVATION OF LEISHMANIA BRAZILIENSIS DOUBLY SENSITIZED WITH UROPORPHYRIN AND DIAMINO‑PHTHALOCYANINE ACTIVATES EFFECTOR FUNCTIONS OF MACROPHAGES IN VITRO
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Affilliation
Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil.
Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil.
Chinese University of Hong Kong Shatin, Hong Kong.
Rosalind Franklin University of Medicine & Science. Chicago Medical School. North Chicago, IL, US.
Rosalind Franklin University of Medicine & Science. Chicago Medical School. North Chicago, IL, US.
Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / Instituto de Investigação em Imunologia. São Paulo, SP, Brasil.
Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil.
Chinese University of Hong Kong Shatin, Hong Kong.
Rosalind Franklin University of Medicine & Science. Chicago Medical School. North Chicago, IL, US.
Rosalind Franklin University of Medicine & Science. Chicago Medical School. North Chicago, IL, US.
Fundação Oswaldo Cruz. Instituto Gonçalo Moniz. Salvador, BA, Brasil / Instituto de Investigação em Imunologia. São Paulo, SP, Brasil.
Abstract
Photodynamic inactivation of Leishmania has been shown to render them non-viable, but retain
their immunological activities. Installation of dual photodynamic mechanisms ensures complete
inactivation of species in the Leishmania subgenus, raising the prospect of their safe and effective
application as whole-cell vaccines against leishmaniasis. Here, we report the successful extension of
this approach to L. braziliensis in the Viannia subgenus, viz. genetic engineering of promastigotes
for cytosolic accumulation of UV-sensitive uroporphyrin (URO) and their loading with red light
excitable phthalocyanines (PC) that was cationized by chemical engineering. The transgenic
strategy used previously produced L. braziliensis transfectants, which gave the same phenotype of
aminolevulinate (ALA)-inducible uroporphyria as found in Leishmania subgenus, indicative of presubgenus
evolutionary origin for similar genetic deficiencies in porphyrin/heme biosynthesis. In the
present study, 12 independent clones were obtained and were invariably ALA-responsive, albeit to
different extent for uroporphyrinogenesis and UV-inactivation. In a separate study, L. braziliensis was
also found, like other Leishmania spp., to take up diamino-PC (PC2) for red light inactivation. In vitro
interactions of a highly uroporphyrinogenic clone with primary macrophages were examined with the
intervention of URO/PC2-medated double-photodynamic inactivation to ascertain its complete loss of
viability. Doubly sensitized L. braziliensis transfectants were photo-inactivated before (Strategy #1)
or after (Strategy #2) loading of macrophages. In both cases, macrophages were found to take up L.
braziliensis and degrade them rapidly in contrast to live Leishmania infection. The effector functions
of macrophages became upregulated following their loading with L. braziliensis photodynamically
inactivated by both strategies, including CD86 expression, and IL6 and NO production. This was
in contrast to the immunosuppressive infection of macrophages with live parasites, marked by
IL10 production. The results provide evidence that photodynamically inactivated L. braziliensis are
susceptible to the degradative pathway of macrophages with upregulation of immunity relevant
cytokine and co-stimulatory markers. The relative merits of the two loading strategies with
reference to previous experimental vaccination were discussed in light of the present findings with L.
braziliensis.
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