Interaction of Helja Lectib isolatd from Helianthus Annus with Candida Albicans inhibits Phagocytosis and promotes phenotypic maturation in dendritic cells

Background: Helja is a sunflower lectin that recognizes mannose motifs. Candidiasis is a fungal infection caused by Candida spp. that affects immunocompromised individuals. This opportunistic yeast can be recognized by dendritic cells (DCs). The aim of this work is to analyze if the interaction between Helja and Candida albicans (Ca) cell wall could inhibit recognition and phagocytosis by DCs and modulate cell maturation. Methods: Bone marrow dendritic cells (BMDCs) were cultured in RPMI 1640 medium supplemented with FLT3-L. Helja was purified from sunflower seeds with a D-mannose-agarose resin. Phagocytosis assay was evaluated by FACS and Confocal Microscopy. C. albicans (NGY152 strain) were stained with FITC and then incubated with Helja for 45 minutes prior to BMDC stimulation. LPS (100 ng/ml) and 4°C incubation were used as controls. BMDCs phenotype was analyzed by FACS. Results: Confocal images and quantification of labeled-yeast revealed that the preincubation of fungal cells with Helja inhibited recognition by BMDCs and induced a statistically significant reduction on phagocytosis compared to control (n=2, ****p<0.0001 Helja-Ca+LPS-treated BMDCs vs Ca+LPS-treated BMDCs). This observation was confirmed by measuring FITC+ dots in the BMDC gate by FACS analysis (Helja-Ca treated BMDCs -53,7%- vs Ca-treated BMDCs -60.4%). Finally, Ca preincubated with Helja improved the upregulation of MHCII compared to untreated cells or Ca-stimulated BMDCs (n=3 **p<0.01). The same pattern was observed in the co-stimulatory molecule CD86, Helja-Ca treated BMDCs induced a significant increase in the percentage of CD86+ cells (54.1% vs 42.0% observed in Ca-treated BMDCS or 24.0% observed in untreated cells, n=3). Conclusions: These data suggest that the mannose-binding lectin blocks epitopes on Candida cell wall important for DC recognition. However, Helja promotes DCs maturation, a process required to activate adaptive immunity, highlighting its potential biomedical application. Fil: Chop, Maia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata; Argentina Fil: Radicioni, Melisa Belén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; Argentina