Preliminary Study On The Role Of Mannan-binding Lectin In Regulating Dimorphism Switching And Immune Response In Candida Albicans

[Background] Candida albicans (C.albicans) is the most common pathogenic fungal, causes kinds of candidiasis. To research immune reactions towards C.albicans infection has dramatically significance. C.albicans can switching its phenotypic to adapt different environmental conditions, was called dimorphic fungal. Yeast form switching to Hyphal form is associated with its infectious.Mannan binding lectin (MBL) is a plasma protein secreted by liver cells, and was called’a key molecule in the innate immune system. At present, reports about the role of MBL palys in the immune reactions of anti-C.albtcnas mostly concentrated on its function of activating the complement system, and promote cell phagocytosis to C.albicans. However, as a innate immune key molecules, whether there are other effects? Whether it it’s will modulate C.albicans’s morphopathogenic switching? And trigger the immunity to C.albicans? So far, there were no reports in this field, but it has great significance in such a research.[Objectives]1, Analyze the influence to C.albicans dimorphic switching treated by different concentrations of MBL.2. Reveal the mechanism of MBL regulating C.albicans dimorphic switching3. Investigat the immune reaction of Peripheral blood mononuclear cell(PBMC) stimulated by heat-killed C.albicans,which modulated by MBL, on Preliminary level.[Methods]1. Separat and purificat human plasma MBL by affinity chromatography.2. To investigate the influence of dimorphic switching modulated by different concentrations of MBL.3. To investigate the key regulatory gene expression in the pahse of MBL moduate C.albicans dimorphic switching by realtime RT-PCR;4.Separate PBMC by Ficoll density gradient centrifugation.5. ELISA detect role of MBL in C.albicans stimulate PBMC to produce cytokines. [Results]1. MBL suppressed C.albicans yeast form swithing to hyphal form;2. MBL suppressed key regulatory HWP1genes expression in C.albicans dimorphic switching;3. Low concentrations of MBL (physiological concentration) can stimulate PBMC to secrete IFN-γ, TNF-α and IL-6in regulating C.albican, high concentration of MBL (ultra physiological concentration) inhibited the secretion of these cytokines.[Conclusions]1. MBL suppress C.albicansdimorphic switching by down regulate HWP1gene expression;2. MBL has concentration-dependent regulation the cytokine secretion stimulated by C.albicans.And all of these indicate that as a key innate immune molecules, MBL play roles in both C.albicansdimorphic switching and the immune responsestimulated by C.albicans.