The Study On Binding Of Human Fibronectin To Aspergillus Fumigatus Conidia

Aspergillus fumigatus is a saprophytic fungus with a world wide distribution and is sometimes recognized as an opportunistic pathogen .Its rate of pathogentic is only lower than Candid albicans in opportunistic pathogen infenction in immunocompromised patients. Aspergillosis prevalence has inceased markedly over the past 30 years.lt has become mainly fatal complications in the numerbers of immunocompromised persons.If not treated , the mortalityof invasive aspergillosis is nearly 100%, and the overall success rate of antifungal therapy is only 34%. New strategies for the prevention and treament of invasive aspergillosis are therefore urgentlyneeded. In the past studied show that metallo proteinases and Arginne protease is the most pathogenic for humans, however, Recertly studies show that in vitro, conidia of A. fumigatus are able to adhere to host cell and mucosal surface is a primary and crucial step in the establishment of infention. The fibronectin is candidates for mediating adherence of conidia to the basement membranes and the extraollular matix.Objective: our studies attempt to gain a better insight into the possible association between the fibronectin and conidia of A.fumigatus and to probe into the realation between the conidia ofA.fumigatus. Its surface receptors and its pathogentic ability, so that finding out the pathogenical mechamisms of conidia of A.fumigatu. Methodes: The studies were divided into two parts: in vivo and in vitro study.The in vivo study was conducted by establishing rat model of acute primary pulmonary aspergillosis get ride of surface recepters with pretretment of the conidia by trypsin to observe the pathogentic of conidia of A. fumigatus in the organs of rats.The in vitro study , Binding of fibronectin to the surface of conidia was examined by immunofluoresence confocal microscopy; morphology of resting and swelling occurred phases were examined by scanning electron microscopy and transmission electron microscopy. The charateristies of fibronectin binding to A.fumigatus conidia were further investigated by flow cytornetry; Flow cytometry was used to determine the apoptosis peak of remove conidia surface receptors with different trypsin concentrations after so that to observe conidia viability.Resultes:(1)Treatment of the conidia by trypsin revealed a marked reducation in the intensity of the binding, suggesting the proteinaceous nature of the fungal receptors. (2)Flow cytometry confirmed that binding of fibronectin to conidia was closedependentand and saturable (P<0.05)(3)The path fluorescent pattern that was readily discernible in the three-dimensional.(4)By the Scanning electron microsopy found that the cell wall surface of resting conidia revealed a characteristic echinulations rodlet pattern of the protrusions. During swelling, the echinulations rodlet layer progressivelydisintegrated Swollen conidia had almost completely shed their outer layer after 4hr incubation in medium 1640+1 %BSA. They then appeared surround by a smooth cell wall layer covered by some strands of fibrillar material, swelling of conidia to germinate tube after 6hr. Unmasking to observed the inner wall by the transmission electron microscope. (5)Without appear apoptosis peak with different trypsin concentrationstreated.(6)Under given conditions conidia concentrations will not lead to heathly SD rats illness, however, it will lead to illness under in immunocompromised patients.Conidia of A. fumiatus can causes some damage of heat, liver, lung and kidney of rats.Conclusion: (1)A. fumigatus resting conidia express high level of which radilabelled fibronectin ligamds-receptors on their surface. Fibronectin binding appeared homogeneronsly distributal over the external echinulations rodlet layer of reting conidia.(2)Binding of fibronectin to conidia was close dependent and saturable. (3)the development of an A. fumigatus infection is thought to be dependent on the adhesion of Aspergillus conidia to host cells and to extracellular matrix. (4)Capability of infection closely...