IL-12 influence mTOR to modulate CD8+ T cells differentiation through T-bet and eomesodermin in response to invasive pulmonary aspergillosis

Abstract

Objective: To investigate whether mTOR signaling pathway regulate the proliferation and differentiation of CD8+ T cells by transcription factors T-bet and Eomes, and explore the role of IL-12 in this biological procedure. Methods: Aspergillus fumigatus spore suspension nasal inhalation was used to establish the invasive pulmonary aspergillosis (IPA) mouse model. After inoculation, rapamycin (2mg/kg) each day or IL-12 (5ug/kg) every other day was given for 7 days. The blood samples were obtained before the mice sacrificed and lung specimens were taken. Pathological sections were stained with hematoxylin and eosin (HE). The number of CD8+effective memory T cells (Tem) and the expression of IFN-γ, mTOR, ribosomal protein S6 kinase (S6K), T-bet and EOMES were measured by flow cytometry. The levels of IL-6, IL-10 and Galactomannan (GM) were determined by ELISA. Results: After IL-12 treatment, the number of CD8+ Tem and the expression of IFN-γ increased significantly; while quite the opposite results were observed when the mTOR pathway was blocked by rapamycin. The expression of mTOR and S6K as well as the level of IFN-γ of the IL-12 treatment group were significantly higher than those in IPA and IPA + rapamycin groups. In addition, IL-12 promoted increasing T-bet and down regulating Eomes to make the Tem transformation. The final immune effector was high level of inflammatory cytokines (IL-6) and low level of anti-inflammatory factors (IL-10) and this strengthened immune response to the Aspergillus infection. Conclusions: The biological effects of Tem could significantly affect IPA infection host immune regulation, which depended on the activation of mTOR signaling pathway by IL-12.