The effects of monoclonal antibodies against iC3b receptors in mice with experimentally induced disseminated candidiasis

Immunotherapy against Systemic Fungal Infections Based on Monoclonal Antibodies

The increasing incidence in systemic fungal infections in humans has increased focus for the development of fungal vaccines and use of monoclonal antibodies. Invasive mycoses are generally difficult to treat, as most occur in vulnerable individuals, with compromised innate and adaptive immune responses. Mortality rates in the setting of our current antifungal drugs remain excessively high. Moreover, systemic mycoses require prolonged durations of antifungal treatment and side effects frequently occur, particularly drug-induced liver and/or kidney injury. The use of monoclonal antibodies with or without concomitant administration of antifungal drugs emerges as a potentially efficient treatment modality to improve outcomes and reduce chemotherapy toxicities. In this review, we focus on the use of monoclonal antibodies with experimental evidence on the reduction of fungal burden and prolongation of survival in in vivo disease models. Presently, there are no licensed monoclonal antibodies for use in the treatment of systemic mycoses, although the potential of such a vaccine is very high as indicated by the substantial promising results from several experimental models.

Candida species adhesion to oral epithelium: factors involved and experimental methodology used

Due to the increasing prevalence and emergence of Non-Candida albicans Candida (NCAC) species, especially in immunosupressed patients, it is becoming urgent to deepen the current knowledge about virulence factors of these species. Adhesion of cells to epithelium is considered one of the major virulence factors of Candida species. However, relatively little is known concerning the adhesion mechanisms of NCAC species to epithelium, as well as about the factors affecting the adhesion process. This review focuses both the mechanisms that regulate the adhesion interactions and the factors involved and the description of the experimental methodology that has been used to perform the adhesion assays.

Oral colonization by Candida albicans

Candida albicans is a commensal yeast normally present in small numbers in the oral flora of a large proportion of humans. Colonization of the oral cavity by C. albicans involves the acquisition and maintenance of a stable yeast population. Micro-organisms are continually being removed from the oral cavity by host clearance mechanisms, and so, in order to survive and inhabit this eco-system, C. albicans cells have to adhere and replicate. The oral cavity presents many niches for C. albicans colonization, and the yeast is able to adhere to a plethora of ligands. These include epithelial and bacterial cell-surface molecules, extracellular matrix proteins, and dental acrylic. In addition, saliva molecules, including basic proline-rich proteins, adsorbed to many oral surfaces promote C. albicans adherence. Several adhesins present in the C. albicans cell wall have now been partially characterized. Adherence involves lectin, protein-protein, and hydrophobic interactions. As C. albicans cells evade host defenses and colonize new environments by penetrating tissues, they are exposed to new adherence receptors and respond by expressing alternative adhesins. The relatively small number of commensal Candida cells in the oral flora raises the possibility that strategies can be devised to prevent oral colonization and infection. However, the variety of oral niches and the complex adherence mechanisms of the yeast mean that such a goal will remain elusive until more is known about the contribution of each mechanism to colonization.

The influence of subinhibitory concentrations of conventional and experimental antifungal drugs on the expression of the iC3b binding protein in Candida albicans strains during filamentation

The influence of six antifungal agents on the expression of the fungal iC3b binding protein was studied in germ-tubes and the mycelial form of several Candida albicans strains. All antifungal agents inhibited not only the yeast-mycelial transformation, but also the formation of rosettes consisting of complement-coated sheep erythrocytes (EAiC3b) bound to the mycelial form of C. albicans. Immunofluorescence as well as ELISA, employing the monoclonal antibody OKM-1 which recognizes the alpha chain of human CR3 and which cross-reacts with the fungal iC3b binding protein, revealed that subinhibitory concentrations of 0.1 mg l(-1) (which did not affect the growth of either germ-tubes or the mycelial form of C. albicans) inhibited the expression of the iC3b binding protein, while lower concentrations (0.01 mg l(-1)) allowed a comparable and sometimes even slightly higher expression of this protein, in comparison with the untreated control. However, treatment with antifungal agents apparently did not lead to a major cleavage of the protein. The dependence of the amount of the iC3b binding protein expressed on the concentration of added antifungal drugs and on the morphological forms of individual C. albicans isolates suggests a drug dependent influence on the expression of this protein and a possible association with the changing virulence of C. albicans strains during antifungal therapy.