Distribution, organization and innervation of gastric MALT in conventional piglet

Abstract

Mucosa-associated lymphoid tissue (MALT) is the initial inductive site for mucosal immunity. It is present in the different layers of the mucosal wall and consists of organized lymphoid tissue which may occur as isolated or aggregated lymphoid follicles (LFs) and interfollicular areas. It is present in many organs, including the pig stomach. Gastric MALT has been intensely studied in experimentally infected pigs but few data are available in healthy, non-gnotobiotic or germ-free animals. In the present study we described the gastric MALT in conventional piglets in the cardiac mucosa of the gastric diverticulum, in the pyloric mucosa, and in the sites of transition from cardiac to oxyntic and from cardiac to pyloric mucosa by means of histological and immunohistochemical stains. The majority of LFs were located in the cardiac mucosa and in the transition from the cardiac to the oxyntic mucosa. Here the LFs were mainly located in the submucosa and reached the mucosa; we called these submucosal lymphoid follicles (SLFs). In the pyloric mucosa and in the transition sites from the cardiac to the pyloric mucosa, LFs were located in the mucosa; we called these mucosal lymphoid follicles (MLFs). In SLFs, a compartmental organization of T and B lymphocytes was present; by contrast, in the MLFs, the T and B cells were intermingled, suggesting the possibility of different roles for the two types of follicles. In the epithelium overlying the lymphoid tissue, numerous T lymphocytes and some cells immunoreactive to cytokeratin-18 were observed. Following the application of the fluorescent tracer DiI into the SLFs of the diverticulum, enteric neurones located in the submucosal plexus were labelled, confirming the interplay between the immune and the enteric nervous system.

Effect of fasting and refeeding on expression of genes involved in the gastric nutrient sensing and orexigenic control of pigs

“…The stomach, due to its aggressive secretion and activity, is a relevant stop point along the digestive tract where new molecules formed in the lumen can be detected and can also affect the arrangement of the lower tracts behaviour. Furthermore, the nervous connection mediated by afferent fibres supports the role of the stomach as an energy balance regulator (Mazzoni et al., ).…”

Effect of free thymol on differential gene expression in gastric mucosa of the young pig

“…However, additional activities are emerging, some of which appear to involve other functional districts of the porcine stomach, such as the pyloric mucosa, including taste-sensing (Colombo et al, 2012), translation of chemosensory signals (Mazzoni et al, 2013) and activation of the mucosa-associated lymphoid tissue (Mazzoni et al, 2011).…”

Age-Related Expression of the Polymeric Immunoglobulin Receptor (pIgR) in the Gastric Mucosa of Young Pigs

“…To date, mucosal immune responses in the stomach have been largely neglected, often as they were considered to be of minor importance in relation to gut diseases, due to the inhospitable microbial environment and to the shorter exposure time to the feed, in comparison with other regions of the gastrointestinal tract. There are no previous reports on the expression of pIgR in pigs, however, the occurrence and distribution of lymphoid follicles in functionally different gastric sites in piglets suggested the existence of the basic machinery for adaptive immune response in the stomach [ 10 ]. Since the stomach is the main portal to the intestine and can be reasonably considered as the first line of defense we chose to investigate the role of the porcine stomach in the defense against pathogens.…”