The Comparison of Defensin Susceptibility and Protease Producibility between Candida Species

*1469 The Comparison of Defensin Susceptibility and Protease Producibility between Candida Species*
T. OHSHIMA¹, K. KOYAMA¹, E. NISHIMURA², J. WANG¹, and N. MAEDA¹, ¹Tsurumi University, Sch. Dental Med., Dept. Oral Microbiology, Yokohama, Japan, ²Research Institute, Morinaga & Co., Ltd, Japan Objectives:The defensins have been well known as antimicrobial peptides and important factors in innate immunity. In this study, we investigated the susceptibilities of each Candida species to human a defensin (HNP) and bdefensin (hBD), which are detected in oral cavity. Also the susceptibilities were compared with their biological properties including protease production (secreted aspartic protease) and cell surface hydrophobicity. Methods:The susceptibility of Candida to defensins was determined by means of radial diffusion assay. The proteinase activity was detected by measuring digested free peptides using BSA as a substrate. Hydrophobicity was assayed as reported previously (Sweet et al., FEMS Microbiol. Lett., 48; 159-163, 1987). Results:C. albicans was not sensitive to hBD-1, but was highly sensitive to HNP-1 and hBD-2. However, under the protease producing condition, the HNP-1 activity was drastically diminished, but hBD-2 was not. Furthermore, we compared the susceptibility of clinical strains of C. albicans. The isolats from HIV positive patients showed slightly lower susceptibility to HNP-1 and hBD-2 than isolates from normal elementary school students, while the producing ability of acidic protease in HIV isolate groups was slightly higher. In comparison, the susceptibilities of other five Candida species to HNP-1 and hBD-2 were classified into 3 groups, namely high, intermediate and low or negative. Their susceptibility depended on the environmental pH, however, their correlation to protease production or cell surface hydrophobicity was not clear. Conclusion:It was predicted the hBD-1, which is constitutively expressed, can not suppress Candida on the surface of oral mucosa, but Candida once begins to enter the tissue, the host seems to resist by the infection-induced hBD-2. HNP-1 also seemed to eliminate Candida on oral mucosa under the absence of protease.
Seq #137 - Defensins 3:45 PM-5:00 PM, Thursday, 7 March 2002 San Diego Convention Center Exhibit Hall C
Back to the Microbiology / Immunology and Infection Control Program Back to the IADR/AADR/CADR 80th General Session (March 6-9, 2002)
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