OBJECTIVETo examine the expression of nucleotide-binding oligomerization domain 1 (NOD1), nuclear factor-kappa B (NF-κB) and human beta-defensins in candidal albicans leukoplakia and to investigate the effect of candida albicans infection on key proteins in NOD1 signaling pathway and the expression of human beta-defensin.

METHODSForty cases of oral leukoplakia samples were collected and stained by hematoxylin-eosin staining, periodic acid-Schiff staining, silver staining and immunohistochemical methods. Nineteen samples were positive with these four methods and judged as candidal albicans leukoplakia, and the other twenty- one samples judged as leukoplakia without candidal albicans infection. Western blotting was used to detect the expressions of NOD1 and NF-κB in these forty samples. In addition, the immunohistochemical method was adopted to investigate the relationship between NOD1, NF-κB, human beta-defensin 1, 2, 3 expressions and candida albicans.

RESULTSThe positive rate of candida albicans in oral leukoplakia was 48% (19/40). The expressions of NOD1 and NF-κB in the candida albicans leukoplakia were lower than that in leukoplakia without candida albicans infection. The mean optical density value of NOD1, NF-κB, human beta-defensin 1, 2, 3 in candidal albicans leukoplakia were 0.25 ± 0.01, 0.30 ± 0.02, 0.35 ± 0.02, 0.42 ± 0.03, 0.36 ± 0.02 respectively, which were significantly lower than that in leukoplakia without candida albicans infection (0.31 ± 0.02, 0.47 ± 0.03, 0.42 ± 0.02, 0.53 ± 0.04, 0.47 ± 0.03) (P < 0.05).

CONCLUSIONSBy inhibiting the NOD1 signaling pathway, candida albicans infection may reduce the expression level of human beta-defensin 1, 2, 3 in oral leukoplakia.