Training of Primary Chicken Monocytes Results in Enhanced Pro-inflammatory Responses

Abstract

Beta-glucan-stimulated mammalian macrophages show an increased responsiveness to secondary stimulation in a nonspecific manner. This phenomenon is known as trained innate immunity. Our study aimed to explore training of primary chicken monocytes. We hypothesized that primary chicken monocytes, similar to their mammalian counterparts, can be trained with β-glucan resulting in increased responses of these cells to a secondary stimulus. Primary blood monocytes of white leghorn chickens were primary stimulated with β-glucan microparticulates (M-βG), LPS, recombinant chicken interleukin-4 (IL-4) or combinations of these components for 48 h. On day 6, the primary stimulated cells were secondary stimulated with LPS. Nitric oxide (NO) production levels were measured as an indicator of pro-inflammatory activity. In addition, the cells were analysed by flow cytometry to characterize the population of trained cells and to investigate the expression of surface markers associated with activation. After the secondary LPS stimulation, surface expression of CSF1R and the activation markers CD40 and MHC-II was higher on macrophages that were trained with a combination of M-βG and IL-4 compared to unstimulated cells. This increased expression was paralleled by enhanced NO production. In conclusion, this study showed that trained innate immunity can be induced in primary chicken monocytes with β-glucan, which is in line with previous experiments in mammalian species. Innate immune training may have potential to improve health and vaccination strategies within the poultry sector.

Immunosecurity: immunomodulants enhance immune responses in chickens

“…Simultaneously, the expression of major histocompatibility complex (MHC) class II and CD40, indicating immunological activation, was also upregulated [85]. These results indicate…”

“…Chicken primary monocytes treated with β-glucan exhibited increased production of nitric oxide compared with cells treated with LPS. Simultaneously, the expression of major histocompatibility complex class II and CD40, indicating immunological activation, was also upregulated [ 85 ]. These results indicate that β-glucan can drive the immune system to better deal with invading foreign substances, although further mechanistic studies using in vivo models are necessary to validate metabolic and epigenetic modulations.…”

Transgenerational Effects of Maternal Immune Activation on Specific Antibody Responses in Layer Chickens

“…In recent years much attention has been paid to this concept of trained innate immunity. Studies in a broad variety of animal species, including mammals, birds and fish, have shown that the innate immune system can be trained, indicating the conserved nature of this immune mechanism (30)(31)(32). Trained innate immunity is defined as the activation of the innate immune system resulting in a memory-like enhanced responsiveness to subsequent triggers driven by epigenetic mechanisms and metabolic reprogramming.…”