To further elucidate the mechanism by which S100A8/A9 promotes DC activation, DCs treated with or without 4 µg/mL of S100A8/A9 were subjected to transcriptome sequencing analysis. By applying the criteria with a log fold change ≥ 2 and
P < 0.05, significantly upregulated genes in four group of S100A8/A9-treated DCs relative to vehicle-treated DCs were filtered and subjected to a Venn diagram analysis, which revealed that 10 genes (
Cxcl3,
Acod1,
Oasl1,
Rtp4,
Irf7,
Ifit1,
Ifit1bl1,
Il1b,
Phf11a, and
Ifit3b) were upregulated simultaneously (
Figs. 5A,
5B). These 10 genes were imported into the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database (
https://cn.string-db.org/), and the top three hub genes of a protein–protein interaction (PPI) network, including
Rtp4,
Acod1 and
Oasl1, were identified using the cytohubba plug-in for Cytoscape software (
Fig. 5C). Among them,
Acod1 attracted our attention because of its critical role in regulating the antigen priming and effector function of DCs in type 2 airway inflammation.
32 qRT-PCR validation result showed that there was an about twofold increase in mRNA expression of
Acod1 in S100A8/A9-treated DCs (
Fig. 5D). To clarify the role of
Acod1 in the regulation of S100A8/A9 on DC function, we silenced
Acod1 expression with siRNA in DCs prior to stimulation by S100A8/A9.
Figure 5E shows the successful knockdown of
Acod1 by
Acod1-specific siRNA, and
Figures 5F to
5H demonstrate that the upregulation of
Il6 and
Il23a mRNA induced by S100A8/A9, but not
Il1b, was markedly reversed by
Acod1 silencing. These results suggest that
Acod1 is a key molecule mediating the promoting effect of S100A8/A9 on DC function.