Chicken immunoregulatory Ig-like receptor families: an overview and expression details on ggTREM-A1.

Paired immunoregulatory receptors facilitate the coordination of the immune response at the cellular level. In recent years, our group characterized chicken homologues to mammalian immunoregulatory Ig-like receptor families. The first part of this review focuses on the current progress on chicken immunoregulatory Ig-like receptor families. One of these receptors is gallus gallus TREM-A1, which was described as the only member of the chicken TREM family with activating potential. The second part of this review presents a study initiated to further characterize ggTREM-A1 expression. For this purpose we established real-time RT-PCR and generated a specific mab to analyze the expression profile of ggTREM-A1 on mRNA and protein level, respectively. GgTREM-A1 mRNA was predominantly expressed in macrophages, but was also detected in brain, bone marrow, bursa, thymus, spleen and PBMC. Analyzing ggTREM-A1 surface expression by mab staining validated the expression on macrophages. Additionally, we showed high expression on blood monocytes, heterophils and NK cells and on monocytes isolated from bone marrow. Moreover, we detected ggTREM-A1 protein also on thrombocytes, B and T cell subsets, but antigen expression seemed to be lower and more variable in these cells. Immunohistochemistry of chicken brain tissue, combining ggTREM-A1 mab and various markers specific for various brain cell subsets showed expression of ggTREM-A1 on microglial cells, but also on neurons, astrocytes and oligodendrocytes. In conclusion, ggTREM-A1 is expressed on a variety of cells, relevant for the immune system, possibly combining physiological function of different mammalian TREM.

Effects of polyunsaturated fatty acids on isolated canine peripheral blood mononuclear cells and cytokine expression (IL-4, IFN-gamma, TGF-beta) in healthy and atopic dogs.

Polyunsaturated fatty acids (PUFA) have been used to treat dogs with atopic dermatitis but the mechanism of action has not been well understood. The aim of this study was to evaluate the in vitro influence of PUFA on canine peripheral blood mononuclear cells (PBMC). PBMC isolated from eleven dogs with atopic dermatitis and eleven healthy control dogs were stimulated with concanavalin A and Dermatophagoides farinae extract in the presence of linoleic acid (LA), gamma-linolenic acid (GLA), alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA)/docosahexaenoic acid (DHA) and GLA/EPA/DHA. Subsequently, quantitative polymerase chain reaction (qPCR) for interferon (IFN)-gamma, interleukin (IL)-4 and transforming growth factor (TGF)-beta m-RNA was performed. In the presence of concanavalin A, only PBMC of healthy dogs showed a gradual reduction in proliferation index from incubation without PUFA to incubation with ALA, EPA/DHA and GLA/EPA/DHA, respectively. A similar reduction was seen in normal and in atopic dogs in the presence of D. farinae allergen after incubation with ALA, EPA/DHA and GLA/EPA/DHA. In both groups IL-4 and IFN-gamma but not TGF-beta gene transcription was upregulated, when cells were incubated with D. farinae. Allergen-induced upregulation was not influenced by incubation with PUFA. These findings suggest that PUFA are able to influence proliferation of peripheral blood mononuclear cells in healthy and atopic dogs but do not seem to influence gene transcription of IL-4, IFN-gamma and TGF-beta.