Analysis of stress effects on intestinal immunity in piglets

Context and challenges 

Under intensive production conditions, and particularly at weaning, pigs are exposed to numerous stress factors that are thought to facilitate the onset of infectious diseases. In the body, these stress factors mainly activate the hypothalamic-pituitary-adrenal (HPA) and adrenergic axes whose mediators (glucocorticoids and catecholamines) modulate immune responses. The intestinal mucosa constitutes a crucial interface with the external environment. Its integrity relies on tight junctions between epithelial cells as well as on various immunological mechanisms. Early weaning of pigs was shown to increase intestinal epithelial permeability. While this effect appears, at least partly, due to the action of corticoliberin through the activation of receptors expressed locally in the intestine, the pathophysiological mechanisms linking the weaning stress  to intestinal epithelial barrier ‘s breakdown remain largely unknown.

Objectives

In this context, this PhD project aims at studying the effects of stress on intestinal immunity in piglets. The student will first describe the effects of stress mediators on intestinal integrity and modulation of intestinal immunity (objective 1), and then describe the advantages of improved and less stressful weaning conditions on these parameters (objective 2).
Thus, the first objective of the PhD project focuses on in vitro and ex vivo studies using a pig intestinal epithelial cell line and pig intestinal explants to identify the effects of adrenergic and/or cortisol stimulation (mimicking stressful situation), on (1) the metabolism of intestinal epithelial cells, (2) the modulation of local immunity and (3) the tissue cohesion and epithelial barrier’s permeability. The second objective will be implemented in a field-based study performed in pigs and will compare the effects of standard weaning’s conditions with improved ones, more respectful of animal welfare, in terms of stress, health and intestinal barrier integrity in pigs from birth to slaughter.

Species concerned

Partnership

• UMR 1300 BIOEPAR INRAE, Département SA : pig health, anti-infectious immunology
• UMR 1331 TOXALIM INRAE, Département ALIM-H : intestinal explants
• Private partnership: Cooperl, Service Recherche et Développement : knowledge in livestock management