Thymus transcriptome reveals novel pathways in response to avian pathogenic Escherichia coli infection

Abstract

Avian pathogenic Escherichia coli (APEC) can cause significant morbidity in chickens. The thymus provides the essential environment for T cell development; however, the thymus transcriptome has not been examined for gene expression in response to APEC infection. An improved understanding of the host genomic response to APEC infection could inform future breeding programs for disease resistance and APEC control. We therefore analyzed the transcriptome of the thymus of birds challenged with APEC, contrasting susceptible and resistant phenotypes. Thousands of genes were differentially expressed in birds of the 5-day post infection (dpi) challenged-susceptible group vs. 5 dpi non-challenged, in 5 dpi challenged-susceptible vs. 5 dpi challenged-resistant birds, as well as in 5 dpi vs. one dpi challenged-susceptible birds. The Toll-like receptor signaling pathway was the major innate immune response for birds to respond to APEC infection. Moreover, lysosome and cell adhesion molecules pathways were common mechanisms for chicken response to APEC infection. The T-cell receptor signaling pathway, cell cycle, and p53 signaling pathways were significantly activated in resistant birds to resist APEC infection. These results provide a comprehensive assessment of global gene networks and biological functionalities of differentially expressed genes in the thymus under APEC infection. These findings provide novel insights into key molecular genetic mechanisms that differentiate host resistance from susceptibility in this primary lymphoid tissue, the thymus.

Selective breeding on natural antibodies in chickens

“…Possible differences in APEC resistance, in this relatively short-time experiment, might be distinguished in innate immunity differences, and protective effects of NAb level (selection) might not have been apparent yet. Several transcriptomic papers of the Lamont-group indicate a major role of innate immunity on APEC resistance/susceptibility: for example, TLR, and TLR pathway expressions were significantly different in (relatively) resistant chickens compared to susceptible chickens in the spleen, blood leukocytes, bone marrow, and the thymus (Sandford et al, 2011;Sandford et al, 2012;Sun et al, 2015a;Sun et al, 2016a;Sun et al, 2016b), except for the bursa (Sun et al, 2015b). The associated TLR1A variants present in the NAb selection lines can be of major influence on APEC resistance in our selection lines.…”

Gallus gallus domesticus: immune system and its potential for generationof immunobiologics

“…The avian and mammal immune systems are organized into groups of immune cells, such as the T cells and B cells, and are homed into organized lymphoid tissues, which are strategically positioned to protect the host (BOeHM et al, 2012;ROSTaMI et al, 2018). Functionally, the lymphoid tissue has been classified into the primary lymphoid tissue, such as the thymus and bursa of fabricius, and the secondary lymphoid tissue, such as the spleen (figure 1) (MadeJ et al, 2015;SuN et al, 2016;IfRaH et al, 2017).…”

“…The hens' primary lymphoid tissue includes the thymus and bursa of fabricius (BOeHM et al, 2012). The thymus is located at the ventral neck region and the bursa of fabricius is reported at the top of the cloacal region (SuN et al, 2016;IfRaH et al, 2017). Primary lymphoid tissue works by selecting lymphocytes such as the T cells (thymus-dependent cells) and the B cells (bursa of fabricius-selected cells) for an appropriate immune response and avoiding autoimmunity (SuN et al, 2016;IfRaH et al, 2017).…”

“…The thymus is located at the ventral neck region and the bursa of fabricius is reported at the top of the cloacal region (SuN et al, 2016;IfRaH et al, 2017). Primary lymphoid tissue works by selecting lymphocytes such as the T cells (thymus-dependent cells) and the B cells (bursa of fabricius-selected cells) for an appropriate immune response and avoiding autoimmunity (SuN et al, 2016;IfRaH et al, 2017). The T and B cell precursors are generated by the lymphoid stem cells in the bone marrow (BOeHM et al, 2012).…”

Novel MicroRNA Involved in Host Response to Avian Pathogenic Escherichia coli Identified by Deep Sequencing and Integration Analysis

“…In chicken spleen, 1,101 and 1,723 differentially expressed genes (DEGs) were found between an APEC-infected group showing severe pathology and a noninfected group at 1 day and 5 days postinfection, respectively (10). Also in other immune-related tissues such as bone marrow, bursa, and thymus, large numbers of significantly differentially expressed genes were detected between susceptible and resistant birds (13–15). These genes promoted the inflammation process mainly through several pathways, such as the Toll-like receptor, Jak-STAT, NOD-like receptor, p53, and cytokine signaling pathways (9–14, 16).…”