Avian pathogenic Escherichia coli-induced activation of chicken macrophage HD11 cells

Area of Science:

• Immunology
• Veterinary Microbiology

Background:

• Avian pathogenic Escherichia coli (APEC) causes significant respiratory illness in poultry.
• The interaction between APEC and chicken macrophages is not well understood.
• The efficacy of chicken macrophages in combating APEC requires further investigation.

Purpose of the Study:

• To investigate the effect of APEC on chicken macrophage (HD11) activation.
• To determine the influence of temperature on APEC phagocytosis by HD11 cells.
• To characterize the immune response of HD11 cells to APEC infection.

Main Methods:

• Assessing phagocytosis of APEC by HD11 cells at different temperatures (37°C vs 41°C).
• Measuring nitric oxide (NO) production by HD11 cells post-infection.
• Analyzing mRNA expression of key cytokines (IL-8, IL-6, IL-1β, IL-10, IFN-β) using RT-qPCR.
• Comparing HD11 cell responses to live and heat-killed APEC.

Main Results:

• APEC phagocytosis by HD11 cells was more efficient at 41°C compared to 37°C.
• HD11 cells demonstrated the capacity to kill APEC.
• Significant production of nitric oxide (NO) and increased mRNA expression of IL-8, IL-6, IL-1β, and IL-10 were observed.
• IFN-β gene expression remained unchanged.
• The immune response was partially dependent on APEC viability, with reduced cytokine expression upon stimulation with heat-killed APEC.

Conclusions:

• APEC infection induces an effector response in chicken macrophages.
• Enhanced nitric oxide production and cytokine gene expression are key components of this response.
• Temperature plays a role in the efficiency of macrophage phagocytosis of APEC.