immunology of infectious and parasitic diseases - XXXVII Congress ...

DIVERGENT OUTCOMES OF THE INTERACTION BETWEEN
MACROPHAGES AND Trichophyton rubrum CONIDIA
FÁBIO SEITI YAMADA YOSHIKAWA (IC)
ALMEIDA (1)
(1) ; SANDRO ROGÉRIO DE
(1) Department of Clinical and Toxicological Analysis, Faculty of
Pharmaceutical Sciences, University of São Paulo
Introduction: Trichophyton rubrum is the main etiological agent of
dermatophytosis - superficial fungal infections of the skin, hair or nails - in
humans. T.rubrum infections are inflammatory, chronic and refractory to most
available treatment schemes. Unrevealing the immunopathological mechanism
behind this mycosis may display new pharmacological targets and help to
design more efficient and safer therapeutic approaches. The aim of this study
was to evaluate the response of different macrophage models to T.rubrum
conidia.
Methods and Results: Thioglycollate-elicited peritoneal macrophages (PM)
and bone marrow-derived macrophages (BMMs) from C57BL/6 mice were
incubated with T.rubrum conidia (MOI 1) for 4, 6, 8 and 10 hours. BMMs were
primed with LPS (1µg/mL) overnight (BMMov) or 30 minutes (BMM30) before
conidia addition. Phagocytosis was observed under optical microscopy. Fungal
viability was assessed by colony forming units (CFU) assay. The supernatants
were collected for cytokine measurements by ELISA. Statistical significance
was determined by Two-Way ANOVA and Bonferroni posttest. All macrophage
populations were able to phagocytose T.rubrum conidia, but, in BMM30
population, conidia could turn into hyphae, growing inside the cells and ending
by disrupting them. On the other side, PMs and BMMov kept the dermatophyte
on it conidial form, without hyphae growth, but conidia were viable even after 10
hours as showed by CFU assay (log CFU: 4h 1,91±0,09; 6h 1,89±0,28; 8h
1,74±0,21; 10h 1,61±0,2). In addition, IL-1β, an inflammatory cytokine produced
by the inflammasome in response to the activation of cytosolic receptors (Nodlike
receptors), was significantly detected only in BMM30 (4h: 44,7±14,0 pg/mL)
while neither PMs nor BMMov produced significant amounts of the cytokine in
response to the infection.
Conclusion: Results showed that macrophages efficiently phagocytosed but
did not eliminate the fungus. Even though activated macrophages could resist
to fungal growth, they showed a fungistatical, but not fungicidal, activity.
Furthermore, IL-1β seemed to be dependent on hyphae growth, perhaps
because NLRs are intracellular receptors which could only come into contact
with fungal determinants through hyphae growth in the cytosol.
Financial Support: FAPESP