PU.1-CD23 signaling mediates pulmonary innate immunity against Aspergillus fumigatus infection by driving inflammatory response.

Background: Aspergillosis is a common cause of morbidity and mortality in immunocompromised populations. PU.1 is critical for innate immunity against Aspergillus fumigatus (AF) in macrophages. However, the molecular mechanism underlying PU.1 mediating immunity against AF infection in human alveolar macrophages (AMs) is still unclear.

Methods: In this study, we detected the expressions of PU.1, CD23, p-ERK, CCL20 and IL-8 and key inflammatory markers IL-1β, IL-6, TNF-α and IL-12 in human THP-1-derived macrophages (HTMs) or PU.1/CD23-overexpressed immunodeficient mice with AF infection. Moreover, we examined these expressions in PU.1-overexpressed/interfered HTMs. Additionally, we detected the phagocytosis of macrophages against AF infection with altered PU.1 expression. Dual luciferase, ChIP and EMSAs were performed to detect the interaction of PU.1 and CD23. And we invested the histological changes in mouse lung tissues transfected with PU.1/CD23-expressing adenoviruses in AF infection.

Results: The results showed that the expressions of PU.1, CD23, p-ERK, CCL20, IL-8, IL-1β, IL-6, TNF-α and IL-12 increased significantly with AF infection, and PU.1 regulated the later 8 gene expressions in HTMs. Moreover, CD23 was directly activated by PU.1, and overexpression of CD23 in PU.1-interfered HTMs upregulated IL-1β, IL-6, TNF-α and IL-12 levels which were downregulated by PU.1 interference. PU.1 overexpression strengthened the phagocytosis of the HTMs against AF. And injection of PU.1/CD23-expressing adenoviruses attenuated pathological defects in immunodeficient mouse lung tissues with AF infection. Adenovirus (Ad)-PU.1 increased the CD23, p-ERK, CCL20, IL-8 levels.

Conclusions: Our study concluded that PU.1-CD23 signaling mediates innate immunity against AF in lungs through regulating inflammatory response. Therefore, PU.1-CD23 may be a new anti-aspergillosis therapeutic for the treatment of invasive aspergillosis with the deepening of gene therapy and its wide application in the clinic.