Aspergillus fumigatus conidia upregulates NOD2 protein expression both in vitro and in vivo

Aim： To determine if NOD2 is involved in host recognition of Aspergillus fumigatus （Af） conidia. Methods： An Af conidia pulmonary infection murine model was established by intranasal inoculation of Af conidia suspensions. Protein levels of NOD2 in lung tissue were determined by immunohistochemistry. A549 and phorbol-12-myristate 13-acetate （PMA）-activated THP-1 cell lines were treated with heat-killed Af conidia, then the presence of NOD2 protein in these cell lines was detected by Western blotting. The ability of muramyl dipeptide （MDP） to induce the secretion of TNF-α after incubation with heat- killed Afconidia was measured by enzyme-linked immunosorbent assay. Results： The expression of NOD2 protein in lung tissue increased after Af conidia infection. Heat-killed Afconidia significantly upregulated NOD2 protein expression in A549 cells and PMA-activated THP-1 cells. Additionally, Af conidia in conjuction with MDP, significantly increased the secretion of TNF-α in A549 cells and PMA-activated THP-1 cells. Conclusion： Afconidia upregulates NOD2 protein expression in vitro and in vivo. These findings indicate that NOD2 protein may respond to Afconidia.