Common messenger molecules and cell types demonstrating neuroendocrine-immune interactions in the chicken

The aim of this study was to identify common messenger molecules used in both the immune and the neuroendocrine systems in birds, and to shed light on a cell type within the bursa of Fabricius that has historically been postulated as a potential neuroendocrine-immune link, the bursal secretory dendritic-like cells (BSDC). An immunocytochemical approach was used to identify neuroendocrine cell populations in the thymus, pituitary and bursa of Fabricius in the chicken. Molecular confirmation of the neuroendocrine cell marker, chromogranin A (CgA) in the thymus tissue of the chicken was reported. Previously the serine protease inhibitor, ovoinhibitor, was localized in bursal follicles, specifically the cortico-medullary border region. The presence of ovoinhibitor was identified and confirmed in the chicken pituitary by this study. Continued focus on the neuroendocrine-immune interactions in chicken immune tissue narrowed the study around the BSDC population. The BSDC are a component of the stromal, non-lymphoid cellular environment of the bursa of Fabricius and are thought to play a role in B-cell maturation and differentiation. They are located mainly along the cortico-medullary border of the bursal follicles in the same area as the majority of the ovoinhibitor-positive cell population. During attempts to isolate the BSDC population by flow cytometry and laser capture microdissection, a cell culture method was developed that enriched the BSDC population by 10-fold. This enriched population was used to evaluate protein product secretion following lipopolysaccharide (LPS) challenge and compared to in vivo challenge with live Salmonella. For the first time, up-regulation of the pro-inflammatory cytokine IL-12 was documented in the chicken following in vivo challenge. In addition, the gene expression of serine protease inhibitors was markedly decreased in the adherent cell population following LPS stimulation. As a result of this research a novel method for the enrichment of an adherent population, including the BSDC, was developed, providing a valuable tool for the analysis of this population during immune stimulation.