Ectophosphatase activity in Candida albicans influences fungal adhesion: study between HIV-positive and HIV-negative isolates.
OBJECTIVE
This study describes the expression of acidic ectophosphatase activity on twenty isolates of C. albicans from oral cavities of HIV-infected children (HIV+) and compares them with fifteen isolates from HIV-negative children (HIV-), as well as the fungal adhesion to epithelial cells and medical records.


METHODS
The activities were measured in intact cells grown in BHI medium for 48 h at 37 degrees C. Phosphatase activity was assayed at pH 5.5 using 4-methylumbelliferyl phosphate. Yeast adhesion was measured using the MA 104 epithelial cell line.


RESULTS
Mean values of ectophosphatase activity were 610.27 +/- 166.36 and 241.25 +/- 78.96 picomoles 4-methylumbelliferone/h/10(7) cells for HIV+ and HIV- group, respectively (P = 0.049). No correlation between C. albicans enzyme activity from HIV children with viral load and CD4 percentual was observed. Yeasts with high enzyme activity, isolated from HIV+ children showed greater adherence than yeasts with basal levels of ectophosphatases from HIV- (Spearman correlation, r = 0.8). Surface phosphatase activity was apparently involved in the adhesion to host cells, as the enhanced attachment of C. albicans to host epithelial cells was reversed by pretreatment of yeast with sodium orthovanadate (1 mM), an acid phosphatase inhibitor.


CONCLUSIONS
These results show that C. albicans from HIV+ has an ectophosphatase activity significantly higher than the other isolates. Yeasts expressing higher levels of surface phosphatase activity showed greater adhesion to epithelial cells. So, the activity of acidic surface phosphatases on these cells may contribute to the early mechanisms required for disease establishment.
Portela
M B
MB
Departamento de Odontopediatria e Ortodontia, Faculdade de Odontologia, UFRJ, Brazil.
Kneipp
L F
LF
Ribeiro de Souza
I P
IP
Holandino
C
C
Alviano
C S
CS
Meyer-Fernandes
J R
JR
de Araújo Soares
R M
RM
D000135:Acid Phosphatase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000818:Animals; D018791:CD4 Lymphocyte Count; D002176:Candida albicans / Q000201:enzymology*; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002648:Child; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000382:microbiology; D006678:HIV / Q000302:isolation & purification; D018023:HIV Seronegativity; D006679:HIV Seropositivity / Q000382:microbiology* / Q000821:virology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D006923:Hymecromone / Q000031:analogs & derivatives; D007202:Indicators and Reagents; D009061:Mouth Mucosa / Q000382:microbiology / Q000473:pathology; D014638:Vanadates / Q000494:pharmacology; D019562:Viral Load
D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; C005359:4-methylumbelliferyl phosphate; D006923:Hymecromone; D014638:Vanadates; D000135:Acid Phosphatase