Lectins as Promising Therapeutics for the Prevention and Treatment of HIV and Other Potential Coinfections

Mazalovska, Milena; Kouokam, J. Calvin

Candida normally lives harmless in several locations of the human body, including the skin and mucosal membranes, but can overgrow and cause a disease named candidiasis in the oral cavity, the gastrointestinal tract, and the genitalia [113] . For instance, in immunocompromised individuals the selective loss of Th17 cells with the progression of HIV infection causes the decay of fungal containment [114] . Interestingly, Candida spp. possess -1,2 mannosylated glycoproteins (e.g., Candida mannan) in addition to other sugars on their cell surface [115] . It is estimated that 80-90% of the cell wall protein mass in Candida are mannose residues added by N-glycosylation, O-glycosylation, and/or glycosylphosphatidylinositol (GPI) anchoring [116] . These sugar molecules are employed by the pathogen to initiate infection of the host cells in various mucosal surfaces. However, Candida spp. also adhere to inert abiotic surfaces, including intravascular and urinary catheters, prosthetic cardiac valves, and denture prostheses [117] . Interestingly, Punica granatum produces a chitin-binding lectin (PgTeL), with antifungal activity against Candida albicans and C. krusei, which are commonly found in immunocompromised individuals such as AIDS patients [118] . In addition, low dose of the plant lectin Con A has been shown to protect mice from a lethal dose of C. albicans by producing tumor necrosis factor (TNF ) and activating macrophages, thus increasing the clearance of C. albicans [119] . SteLL, a chitin-binding lectin isolated from the leaves of the plant Schinus terebinthifolius, has shown antifungal activity against C. albicans at a minimal inhibitory concentration (MIC) of 6.5 g/ml [120] . Lectins isolated from legumes have also shown antifungal activity. For instance, ConBr from Canavalia brasiliensis and DvioL isolated from Dioclea violacea have both demonstrated antifungal activity against C. albicans at a MIC of 16 g/ml [121] . Another lectin, CasuL, alters the cell morphology and damages the cell wall in Candida krusei, indicating its potent antifungal properties [111] .