Peroxidase originates from two main sources in the oral cavity. Salivary peroxidase is synthesized by acinar cells in major salivary glands and myeloperoxidase (MPO) is derived from the neutrophil primary granules. Monocytes also contain MPO in their primary granules, whereas macrophages are known to lack this enzyme (Marodi et al., 1991). These enzymes combine with H2O2 and thiocyanate or iodide ions to produce hypothiocyanate, or hypoiodite, which are powerful oxidizing agents. In the presence of chloride ion, MPO also converts H2O2 into hypochlorous acid and monochloramine, the two potent microbiocidal agents. MPO plays a critical role in the fungicidal activity of PMN in vitro, and phagocytes genetically deficient in MPO fail to kill C. albicans (Lehrer and Cline, 1969). Exogenously supplied MPO also elevates the ability of human macrophages to kill C. albicans (Weber et al., 1987) and activates cytokine secretion and the respiratory burst of these cells (Lefkowitz et al., 1996; Marodi et al., 1998).
Salivary peroxidase has potent fungicidal activity in vitro (Majerus and Courtois, 1992; Bosch et al., 2000). However the role of salivary peroxidase in oral Candida clearance in vivo is unclear since the presence of phosphate at concentrations equivalent to those found in saliva suppresses its fungicidal activity (Lenander-Lumikari, 1992). Human MPO deficiency is the most frequently encountered neutrophilic lysosomal enzyme deficiency. The importance of MPO in clearing Candida infections in vivo has been suggested by case reports, which have demonstrated that patients with this deficiency may develop rapidly disseminated cutaneous C. albicans infection (Nguyen and Katner, 1997). Similarly, patients with hereditary MPO deficiency have an increased susceptibility to oral thrush and invasive oral candidiasis (Okuda et al., 1991), therefore it appears that MPO activity may also play a role in limiting oral infection in vivo.
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The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.