The Expression Of HBD-2mRNA And Peptides During Oral Epithelial Cells Infections By Candida Albicans

Background: Humanβ-defensins (HBDs) are a group of small cationic cysteine-rich peptides with a broad-spectrum antimicrobial activity against vast array of oral pathogens including Candida species. They are one of few evolutionarily well-conserved antimicrobial peptides which remain effective in host innate defense. The most intensively investigated HBDs thus far are HBD-1, 2, and 3, which have been detected in the confines of the oral milieu in gingival epithelia, salivary glands, saliva, and gingival crevicular fluid. HBD-1 and 2 are active against Gram-negative bacteria and yeasts, and HBD-3 has potent antimicrobial activities against both Gram-positive and Gram-negative bacteria even at low concentrations. While the antifungal activity of HBDs has been characterized to some extent, the exact role they play in host defense against fungal infection is not well defined. Previous work has shown that the salivary levels of HBD-1 and 2 in patients with oral Candidiasis are lower than in healthy individuals, whereas the HBD-2 peptide expression in human buccal epithelia with candidiasis was greater than in normal buccal epithelia. These reports suggest that HBDs may be involved in the Candida–host interaction in the oral environment.Objective: To analyze the pathogenicity of candida albicans through it adhere to oral epithelial cells. To determine the expression of Human beta Defense 2 (HBD-2) in oral epithelial cells and studied to define the influence of C. albicans infection on their expression. Discuss the roles of HBD-2 to defense against C. albicans infection early and inhibit C. albicans colonize in oral epithelial cells, provide additional evidence for the innate immune function and the molecular mechanism of HBD-2 and provide a new strategy to prevent the oral candidiasis.Methods: Oral squamous cell carcinoma cell lines KB cell as the research object, KB cells was infected with C.albicans for 3, 6, 12, 24 hours, quantity the number of C. albicans cells adhering to the KB cells, observed the C. albicans viability and determine the transformation of C.albicans from blastospores to hyphae; KB cells was infected with blastospores phase, hyphae phase, and inactivated C.albicans for 6, 12, 24 hours, determine the expression of hBD-2mRNA and peptides in each group by enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR), the date was compared with controls.Results: 1. C.albicans begin adhere to KB cell after it was infected, the number of KB cells adhered was increased gradually within 24 hours of infection. 2. The percentage of the hyphal form rose from 23% after a 3h contact to more than 83% after a 24 hours contact. Viability and growth analyses showed that all C.albicans that adhered to KB cells were alive, however, their numbers were significantly reduced, from 1.5×105/cm2 after a 3h infection to around 103/cm2 after a 24 hours infection. 3. HBD-2 was basally expressed in KB cells, After 6 hours of Infection, the expression was no difference (P>0.05) between experiment groups and control group; After 12 hours of infection, the expression was significant upregulation in the blastospores group(93.974±6.426)and hyphae group(72.287±2.839) than the controls (37.380±5.663) (P<0.05), the difference was statistically significant; After 24 hours of infection, the expression of HBD-2 in experiment groups was upregulation compared to the controls(P<0.05), but it begin decrease in the blastospores group(80.851±7.860)and hypha group(63.932±8.070), the blastospores group decrease less than the hyphae group (P<0.05). 4. HBD-2mRNA expression was significantly upregulated in KB cell after 24 hours of infection with the blastospores phase C. albicans(P<0.001), but down-regulated with hyphae phase C. albicans, compared with control(P<0.05), the difference was statistically significant.Conclusion: 1. Oral epithelium appears to be capable of recognizing the invasion of C. albicans at a very early stage of infection and can inhibite the growth and adherence of C. albicans. 2. HBD-2mRNA and peptides was basally expressed in oral epithelial cells. Blastospores, hyphae phase and inactivated C.albicans all can induce the HBD-2mRNA and peptides levels upregulated in oral epithelial cells. 3. The expression of HBD-2 was induced after a certain period of infection with C.albicans, but the expression regressed as hyphal invasion progressed.