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Author Spotlight: Achieving High-Purity In Vitro Differentiation of Th17 Cells Using Cytokine Concentration Modulation
Published on: October 25, 2024
Glaesserella parasuis induces IL-17 production might through PKC-ERK/MAPK and IκB/NF-κB signaling pathways
Xinyi He1, Xin Song1, Hui Cao1
1College of Animal and Veterinary Sciences, Southwest Minzu University, Chengdu 610041, China.
Abstract:
In our previous study, the outer membrane protein P2 of Glaesserella parasuis (G. parasuis) induced the production of interleukin-17A (IL-17A) in host cells. However, how the G. parasuis infection produces IL-17A in the host is unknown. In this study, at 48 hpi in piglets, the proportion of Th17 cells in the peripheral blood significantly increased as determined by flow cytometry, but the overall proportion was low. IL-17 mRNA and protein levels significantly increased in the lungs and spleens of infected piglets. Histopathological examination staining, immunohistochemistry and viability counts, revealed that IL-17 expression might be positively correlated with bacterial content and the degree of pathological injury in lung and spleen tissues. Furthermore, when infected with the G. parasuis Nagasaki strain compared with avirulent strain C5, the primary porcine alveolar macrophages (PAMs) significantly produced IL-17 in a time-dose dependent manner. In addition, we demonstrated that PKC, MEK and NF-κB signaling pathways were essential for G. parasuis-induced IL-17 production because the addition of corresponding inhibitors dramatically reduced IL-17 mRNA production. The phosphorylation levels of PKC, ERK1/2 and IκB in G. parasuis-infected primary PAMs also increased significantly as the infection dose increased as assessed by western blotting. Thus, these finding imply that IL-17 induced by G. parasuis infection is dependent on activation of PKC-ERK/MAPK and IκB/NF-κB signaling pathways.
Insights
Glaesserella parasuis infection significantly increases interleukin-17A (IL-17A) in piglets, particularly in lungs and spleens. This response is mediated by the activation of PKC-ERK/MAPK and IκB/NF-κB signaling pathways in macrophages.
Area of Science:
- Veterinary Immunology
- Bacterial Pathogenesis
- Host-Pathogen Interactions
Background:
- Previous studies identified the outer membrane protein P2 of Glaesserella parasuis (G. parasuis) as an inducer of interleukin-17A (IL-17A).
- The precise mechanisms by which G. parasuis infection leads to IL-17A production in the host remained unclear.
Purpose of the Study:
- To investigate the role of IL-17A in G. parasuis infection in piglets.
- To elucidate the signaling pathways involved in G. parasuis-induced IL-17A production.
Main Methods:
- Flow cytometry to assess Th17 cell proportions in peripheral blood.
- Measurement of IL-17 mRNA and protein levels in lung and spleen tissues.
- Histopathological examination, immunohistochemistry, and viability counts.
- Infection of primary porcine alveolar macrophages (PAMs) with different G. parasuis strains.
- Western blotting to analyze signaling pathway activation (PKC, ERK1/2, IκB).
- Use of specific pathway inhibitors (PKC, MEK, NF-κB).
Main Results:
- A significant increase in IL-17 mRNA and protein levels was observed in the lungs and spleens of infected piglets.
- IL-17 expression correlated positively with bacterial load and pathological damage in tissues.
- Primary PAMs produced significantly more IL-17 in a time- and dose-dependent manner when infected with virulent G. parasuis strains.
- PKC, MEK, and NF-κB signaling pathways were identified as essential for G. parasuis-induced IL-17 production, as evidenced by reduced IL-17 mRNA levels upon inhibitor treatment.
- Increased phosphorylation of PKC, ERK1/2, and IκB was observed in infected PAMs.
Conclusions:
- G. parasuis infection triggers IL-17 production in piglets, primarily in the respiratory tract and spleen.
- The activation of the PKC-ERK/MAPK and IκB/NF-κB signaling pathways is crucial for G. parasuis-induced IL-17 production.
- IL-17 expression is linked to bacterial burden and disease severity in G. parasuis infections.
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