Gene expression of Toll-like receptors, cytokines and a nuclear factor and cytokine secretion in DH82 canine macrophage cells infected with Brucella canis.

Canine brucellosis caused by Brucella canis infection occurs mainly in dogs, and is a zoonotic disease that also has the possibility of infection in humans. Many studies have been conducted to understand the immunopathological mechanism of B. canis infection. However, the precise immune mechanism remains to be elucidated because compared to other Brucella spp., B. canis has different immune evasion mechanisms. In this study, gene expression levels of Toll-like receptors (TLRs) and TLR-associated molecules and cytokine production were analyzed to figure out the roles of immune-related host factors in B. canis infection. Time-dependent gene expression of TLRs (1-10) and TLR-related molecules (TNF-α, IL-5, IL-23, CCL4, CD40 and NFκ-B) and release of Th1, Th2 and Th17-related cytokines (IFN-γ, IL-1ß, IL-4, IL-6, IL-10 and IL-17A) were investigated in DH82 canine macrophages infected with B. canis. Time-dependent induction of TLRs 3, 7 and 8 was observed, and TLR 7 had the highest expression level (p <0.05). The expression levels of all TLR-related genes were significantly increased after infection. In particular, the expression of the CCL4 and IL-23 genes was highly induced. The amounts of IL-1ß, IL-6 and IL-10 were significantly increased by B. canis infection, but the amounts of IL-4 and IL-17A were not. The production of IL-1ß and IL-6 was the highest at 24 hr after B. canis infection (p <0.05). This study demonstrates that TLRs 3, 7 and 8 are prominent sites of to immune response induction with the production of related cytokines and a nuclear factor in DH82 cells infected with B. canis. These results suggest a sequential immune mechanism of B. canis infection, involving TLRs, cytokines and their associated factors.

Global Gene Networks in 3D4/31 Porcine Alveolar Macrophages Treated with Antigenic Epitopes of Actinobacillus pleuropneumoniae ApxIA, IIA, and IVA.

Actinobacillus pleuropneumoniae (App) is the causative agent of porcine pleuropneumonia. Although App produces several virulence factors, Apx toxins, the primary App virulence factors, have been the focus of numerous studies. However, the host response against the Apx toxins has not been elucidated at the transcriptomic level. Therefore, in this study, we examined the response of an immortalized porcine alveolar macrophage cell line (IPAM 3D4/31) to four antigenic epitopes of the App exotoxins, ApxIA, IIA and IVA. The antigenic epitopes of the Apx toxins (ApxIA Ct, ApxIIA Nt, ApxIVA C1 and ApxIV C2) were determined by an in-silico antigenicity prediction analysis. Gene expression in IPAMs was analyzed by RNA-Seq after treatment with the four proteins for 24 h. A total of 15,269 DEGs were observed to be associated with cellular and metabolic processes in the GO category Biological Process and nuclear receptors and apoptosis signaling in IPA analyses. These DEGs were also related to M2 macrophage polarization and apoptosis in IPAMs. These host transcriptional analyses present novel global gene networks of the host response to treatment with Apx toxins.