Antifungal Effects of Lysozyme and Lactoferrin against Genetically Similar, Sequential Candida albicans Isolates from a Human Immunodeficiency Virus-Infected Southern Chinese Cohort

Abstract

A variety of innate defense factors in saliva such as lysozyme and lactoferrin contribute to mucosal protection and modulate Candida populations in the oral cavity. It is also known that in human immunodeficiency virus (HIV)-infected individuals significant variations in the concentrations of lysozyme and lactoferrin in saliva occur during disease progression. Therefore, the aim of this study was to determine the in vitro susceptibility to human lactoferrin and hen egg white lysozyme of genotypically similar oral Candida albicans isolates obtained from six HIV-infected ethnic Chinese during sequential visits over a 12-month period. The similarity of the genotypes (50 in total) was evaluated using a randomly amplified polymorphic DNA assay. A blastospore viability assay was performed to evaluate the sensitivity of the organisms to lysozyme and lactoferrin. Exposure to physiological concentrations of either lysozyme (30 g/ml) or lactoferrin (20 g/ml) caused a rapid loss of viability among all isolates to a varying extent. None of the sequential C. albicans isolates demonstrated significant differences in sensitivity to either protein from one visit to the next; similar results were noted when the different genotypes from the same individual were compared. On Spearman correlation analysis of two genotypes that were sequentially isolated from a single patient, a significant negative correlation between lysozyme (r ‫؍‬ ؊0.88; P < 0.02) (but not lactoferrin) resistance and the duration of HIV disease was seen. These results imply that a minority of C. albicans isolates that persist intraorally in individuals with HIV disease develop progressive resistance to innate salivary antifungal defenses such as lysozyme, possibly as an adaptive response. However, the vast majority of the Candida isolates appear to succumb to these nonspecific host immune mediators abundantly present in the oral environment.Candida albicans is the main cause of oral candidiasis in patients with human immunodeficiency virus (HIV) infection and AIDS (13, 38). Almost 90% of AIDS patients suffer from oropharyngeal or esophageal candidiasis at some stage of their disease (38). As HIV infection progresses, so does the oral colonization by Candida, and it eventually becomes a permanent oral resident despite prophylactic antifungal therapy (1,36,45). With the development of DNA fingerprinting methods, it is now possible to investigate strain relatedness and emergence of novel strains of C. albicans by sequentially sampling a cohort of individuals either with or without symptomatic oral candidiasis. Several authors have shown that AIDS patients are frequently infected with the same C. albicans strains over recurrent episodes of oral thrush (5, 34, 47, 60), and others have found, for instance in Candida vaginitis, that the same yeast strain may persist through successive episodes of infection (48,49). Although these and other studies have traced the yeast genotypes over multiple infection episodes (29,36,45), not many have investigated the phenotypic attr...

Biofilm-Forming Ability ofCandida albicansIs Unlikely To Contribute to High Levels of Oral Yeast Carriage in Cases of Human Immunodeficiency Virus Infection

“…The C. albicans isolates used in this study included 20 oral isolates from HIV-free individuals and 26 oral isolates from HIV-infected patients. The isolation and identification of Candida from HIV-infected and healthy individuals were performed as described previously (28). All 46 isolates were subcultured from thawed suspensions of pure isolates stored at the Oral Bioscience Laboratory at the Prince Philip Dental Hospital, University of Hong Kong.…”

Immunopathogenesis of Oropharyngeal Candidiasis in Human Immunodeficiency Virus Infection

“…Lysozyme is found at a concentration range of 1.5 to 57 g/ml of saliva (350,419), and its antifungal properties are thought to be mediated by the enzymatic hydrolysis of N-glycosidic linkages in the microbial cell wall and injury to the cytoplasmic membrane following direct cationicprotein binding (279). Interestingly, concentrations of salivary lysozyme are increased in HIV-infected patients with or without oral candidiasis (20,199,274,467), and a trend toward progressive in vitro resistance to lysozyme has been observed in genetically similar, sequential oral C. albicans isolates from patients infected with HIV (379). Because the concentration of lysozyme is increased in HIV-infected patients while the anticandidal activity of saliva is decreased, the contribution of salivary lysozyme to limiting the proliferation of C. albicans in the oral cavity of these patients appears doubtful.…”

“…The predisposition to oral candidiasis in HIV-infected patients is thus not convincingly associated with defective production of lactoferrin. In contrast to lysozyme, serial genotypically identical oral isolates of C. albicans from HIV-infected patients did not develop progressive in vitro resistance to lactoferrin (379). The therapeutic potential of lactoferrin for the treatment of OPC has recently led to the development of mucoadhesive lactoferrin tablets with fungicidal activity against C. albicans and C. glabrata (239).…”

“…Because saliva from HIV-infected patients shows decreased anticandidal activity (258), several investigations have focused on identifying putative defects in salivary antimicrobial proteins which may favor oral candidiasis in HIV infection. Lysozyme and lactoferrin are two major nonimmu-nological antimicrobial proteins in saliva which possess concentration-, time-, and strain-dependent fungicidal activity against C. albicans in vitro (379,466). Lysozyme is found at a concentration range of 1.5 to 57 g/ml of saliva (350,419), and its antifungal properties are thought to be mediated by the enzymatic hydrolysis of N-glycosidic linkages in the microbial cell wall and injury to the cytoplasmic membrane following direct cationicprotein binding (279).…”

Single-Nucleotide Polymorphisms (SNPs) in Human β-Defensin 1: High-Throughput SNP Assays and Association with Candida Carriage in Type I Diabetics and Nondiabetic Controls

“…This phenomenon is also evident in the nondiabetic population, in which some individuals have a greater propensity for fungal infection than others. This variability in pathogenic response may be related to variations in host innate immune defenses such as histatins (36), lactoferrins and lysozyme (32), and defensins. The development of candidal infection is in part determined by the mechanical adhesion of the Candida cells to the epithelium and subsequent colonization.…”