The Effect And Molecule Mechanism Of Cofilin On Aspergillus Fumigatus Internalization Into Alveolar Epithelial Cell

Background and objectives Invasive pulmonary aspergillosis is the most common invasive fungal infection. The incidence and mortality of the disease remain high, hence the research on its pathogenesis has significance importance. The internalization of Aspergillus fumigatus into alveolar epithelial cells (AECs) is tightly controlled by host cellular actin dynamics, which requires close modulation of ADF (actin depolymerizing factor)/cofilin family. However, the role of cofilin on A. fumigatus internalization into AECs remains unclear.Methods 1) The immunofluorescence staining was used to observe the rearrangement of cell actin cytoskeleton and the distribution of p-cofilin during the internalization of A. fumigatus into A549 cells.2) Western blot was used to detect the expression of cofilin/p-cofilin proteins.3) RT-PCR was used to detect the expression of cofilin mRNA.4) And he nystatin protection method was used to analyses the internalization of A. fumigatus into A549 cells.Results 1) Here we demonstrated that once germinated, A. fumigatus conidia were able to induce phosphorylation of cofilin in A549 cells at early stage of internalization.2) The modulation of cofilin activity by overexpression, knockdown, or mutation of cofilin gene in A549 cells decreased the efficacy of A. fumigatus internalization. Breaking the balance of cofilin phosphorylation cycle by LIM kinases inhibitor or overexpression of slingshot phosphatases could also impede A. fumigatus intemalization.3) Either C. botulimun C3 transferase (specific inhibitor to RhoA) or Y27632 (specific inhibitor to ROCK) could reduce the intemalization of A. fumigatus and the level of phosphorylated-cofilin. β-1,3-glucan, the major content of conidial cell wall and its receptor, dectin-1 on host cells seemed not related to cofilin phosphorylation during A. fumigatus infection.Conclusion These results indicated that cofilin might be involved in modulation of A. fumigatus internalization into type Ⅱ alveolar epithelial cells through RhoA-ROCK-LIM kinases pathway.