Investigating the development of Peyer’s patches and the transcriptome of M cells in chickens
View/ Open
Zeinali LathoriS_2023.pdf (11.44Mb)
Date
15/05/2023Item status
Restricted AccessEmbargo end date
15/05/2024Author
Zeinali Lathori, Safieh
Metadata
Abstract
Considering the approximately 8 billion world population in 2022 and its
predicted growth rate of 1.1% per year, there is an increasing demand for
food for this growing population. Poultry products such as meat and eggs are
excellent sources of protein. Thus, the poultry industry has grown rapidly to
meet the global demand for food. Poultry producing sectors heavily rely on
vaccination to prevent poultry diseases, maintain welfare, and minimise the
risk of disease outbreaks. Applying vaccines through mucosal surfaces such
as drinking water and spray is a common approach on an industrial scale.
Understanding the mechanisms by which vaccines are taken up at mucosal
surfaces and induce immune responses will help improve vaccine design and
targeting.
Mucosal surfaces are protected by the immune responses that are generated
by mucosa-associated lymphoid tissues (MALT). Peyer’s patches (PP) are
the important parts of MALT which are located in the small intestine. PP are
overlaid by follicle-associated epithelium (FAE) containing specialised
epithelial cells called M cells that sample gut contents and deliver them to the
underlying immune cells to induce antigen-specific immune responses. A
better understanding of PP development could contribute to vaccination
strategies in the poultry industry. In addition, the functional characteristics of
M cells, i.e., translocating antigens across the epithelium to the gut-resident
immune system, can be exploited for mucosal vaccine delivery. In chickens,
developmental studies of PP has been hampered since chicken PP are not
macroscopically as nodular as their mammalian counterparts. Furthermore,
there is limited research on the immunobiology and the development of
chicken intestinal M cells due to the lack of appropriate M cell-associated
markers. Using CSF1R-eGFP reporter transgenic chickens, PP are
detectable under the whole-mount microscope as PP contain the
aggregations of CSF1R+ cells. Moreover, in these chickens, it was
demonstrated that along with mononuclear phagocytes, M cells in the bursa
of Fabricius, large intestine, and lung express CSF1R. Therefore, this thesis
aimed to study the development of chicken PP and to identify the gene
expression profile of chicken bursal M cells using CSF1R-eGFP reporter
transgenic chickens, as well as to develop an in vitro model that facilitates
chicken intestinal M cell studies. Using RNA sequencing (RNA-seq) analysis
of isolated bursal M cells, M cell-associated genes were determined and
used to detect M cells in the small intestine and in vitro models.
The spatiotemporal development of chicken PP was studied to examine the
hypothesis that the organogenesis of all PP initiates during embryonic
development and continues post-hatch. The results demonstrated that
chicken PP anlagen are present at predetermined locations at embryonic day
18 (ED18) and their development and expansion continue post-hatch. The
distribution and location of up to 7 PP were discovered in the chicken small
intestine and PP structure was observed in 2- and 8-week-old chickens
based on the germinal centre formation and the reduction of goblet cells in
the overlying epithelium through histology.
In this thesis, it was hypothesised that M cell-associated gene signatures are
conserved between mice and chickens and between M cells located in
different parts of the chicken MALT. In contrast to the intestine, where finding
a location with a high density of M cells is hard, FAE covering bursal follicles
are enriched with M cells. Accordingly, using CSF1R-eGFP reporter
transgenic chickens, the gene expression profile of bursal M cells was
identified, from which shared M cell-associated genes between mice and
chickens and chicken-specific M cell-associated genes were determined. The
functional enrichment analysis of upregulated genes in bursal M cells
indicated the association of these genes with translocating antigens and
macromolecules, aligned with the function of M cells. This study also
proposed putative cytokines involved in bursal M cell development and
confirmed the protein expression of allograft inflammatory factor 1-like
(AIF1L), SRY-box transcription factor 8 (SOX8) and Ets transcription factor
PU.1 in bursal M cells. In addition, the co-localisation of SOX8 and CSF1ReGFP
was demonstrated in the bursa of Fabricius, caecal tonsil, and lung,
but not in the small intestinal PP.
In mammals, intestinal M cells are derived from crypt-based stem cells that
are induced by the cytokine receptor activator of the nuclear factor-κB ligand
(RANKL). Applying RANKL to 2D and 3D intestinal organoids or enteroids
induces M cell differentiation and the expression of M cell-associated genes.
This study investigated whether the differentiation of intestinal M cells is
induced by adding recombinant chicken RANKL to chicken 2D and 3D
enteroids, similar to mammalian M cell models. Both the apical and
basolateral application of RANKL did not consistently increase the
expression of chicken M cell-associated gene signatures in 2D and 3D
enteroids derived from ED18 villi. These observations may be linked to the
embryonic origin of the chicken enteroids or the possible requirement of
additional cytokines to induce chicken M cells in vitro.
In summary, this thesis has provided a better insight into PP distribution and
development from ED18 to 8-week-old chickens that can be implemented in
future research on intestinal mucosal immunity and in ovo or post-hatch
vaccine targeting. Moreover, the RNA-seq and protein expression analysis in
this study offer a valuable resource to better understand the molecular
immunobiology, cellular development, and function of chicken M cells and to
identify potential surface receptors for M cell-targeted vaccine strategy.
Related items
Showing items related by title, author, creator and subject.
-
Acid and alkaline phosphomonoesterases in normal and tumour-bearing chickens, and in certain spontaneous, virus associated and chemically induced chicken tumours: a histochemical and biochemical study
Yuan, Chang-Kuo (The University of Edinburgh, 1950)1. Eighteen different tissues from normal 6 -week -old chickens and various tissues from tumour-bearing chickens were studied both histochemically and biochemically for the distribution and content of the acid and ... -
Genetic studies of incubation behaviour and morphological traits in chickens
Basheer, Atia (The University of Edinburgh, 2013)Finding the genes that underlie variation in production and developmental traits has important economic applications. Incubation behaviour represents a loss of production in conventional breeds of chicken adapted ... -
Hormonal basis of decreased growth rate in broiler chickens exposed to high environmental temperatures
Kan, Peixiang (The University of Edinburgh, 1994)Broiler chickens and other meat animals grow very slowly at high ambient temperatures (such as those experienced in tropical and subtropical countries), and also exhibit a high mortality rate under these conditions. ...