Effect of fatty acids on biofilm formation, oxidative stress and antifungal susceptibility of Candida albicans and Candida dubliniensis
Abstract
English: Candida albicans and C. dubliniensis are commensals of the gastrointestinal and
genitourinary tract in healthy individuals. However, in diseased individuals they can
cause superficial infections to deep seated mycoses. Both species form mycelial
networks called biofilms, and formation of biofilms results in increased resistance
towards antifungal compounds currently in use. Therefore, there is a need for
alternative antifungal compounds such as fatty acids. Research has shown that
supplementation of growth medium with polyunsaturated fatty acids (PUFAs), increased
the unsaturation index and made cells susceptible to lipid peroxidation and cell death.
During this study this phenomenon was evaluated on biofilms of C. albicans and C.
dubliniensis using selected PUFAs. Due to differences in the carbon chain length and
saturation of fatty acids, they interact differently with the cell membrane and will have
different peroxidisability values. The results from the study showed C18:4 n-3 and
C20:5 n-3 were taken in by the cell and resulted in increased unsaturation index. The
results further indicated oxidative stress-induced apoptosis following supplementation
with C18:4 n-3 and C20:5 n-3 in biofilms of both C. albicans and C. dubliniensis. The
induction of apoptosis following supplementation by C18:4 n-3 and C20:5 n-3 was
confirmed by mitochondrial membrane potential assay, Annexin V-FITC staining,
TUNEL assay and DAPI staining. The use of C18:4 n-3 in synergism with amphotericin
B resulted in decreased dosage of the antifungal compound needed to inhibit biofilms of
C. albicans and C. dubliniensis. Afrikaans: Candida albicans en C. dubliniensis is kommensale van die gastro-intestinale en
genitor-urinêre weg van gesonde individue. In siek individue kan hulle egter
oppervlakkige tot sistemiese mikoses veroorsaak. Beide spesies vorm misiliêre
netwerke wat biofilms genome word, en biofilmvorming veroorsaak verhoogde
weerstand teen antifungale middels wat tans in gebruik is. Dus is daar ‘n behoefte aan
alternatiewe antifungale middels soos vetsure. Navorsing het getoon dat byvoeging van
polionversadigde vetsure (PUFAs) tot groeimedia, die onversadigingsindeks verhoog en
selle vatbaar maak vir lipiedperoksidasie en dood. Hierdie verskynsel is gedurende
hierdie studie geëvalueer op biofilms van C. albicans en C. dubliniensis met sekere
PUFAs. As gevolg van die verskille in koolstofkettinglengte en versadiging van vetsure
verskil die interaksies wat hulle met selmembrane het en sal hulle verskillende vlakke
van peroksideerbaarheid hê. Die resultate van hierdie studie het aangetoon dat C18:4
n-3 en C20:5 n-3 deur die selle opgeneem is en ‘n toename in onversadigingsindeks
veroorsaak het. Verder het die reulate getoon dat behandeling van beide C. albicans en
C. dubliniensis biofilms met C18:4 n-3 en C20:5 n-3 gelei het tot oksidatiewe stress
veroorsaakde apoptose. Die induksie van apoptose na behandeling met C18:4 n-3 en
C20:5 n-3 is bevestig met ‘n mitochondriale membraanpotensiaaltoets, Annexin V-FITC
kleuring, TUNEL toets en DAPI kleuring. Die gebruik van C18:4 n-3 in sinergisme met
amfoterisien B het gelei tot ‘n verlaagde dosis van die antifungale middel wat nodig was
om biofilms van C. albicans en C. dubliniensis te inhibeer.