Marie Allard, Jordan Marchand, Pierre Mormède, Grégoire Mignot, Yvon Billon, Julie Hervé, Elena Terenina, Jean-Marie Bach, Karine Haurogné, Laurence De Beaurepaire, Julien Jacques, Elodie Bacou, Blandine Lieubeau, Immuno-Endocrinologie Cellulaire et Moléculaire (IECM), Ecole Nationale Vétérinaire de Nantes-Université de Nantes (UN)-Institut National de la Recherche Agronomique (INRA), Lipides - Nutrition - Cancer (U866) (LNC), Université de Bourgogne (UB)-Institut National de la Santé et de la Recherche Médicale (INSERM)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement-Ecole Nationale Supérieure de Biologie Appliquée à la Nutrition et à l'Alimentation de Dijon (ENSBANA), HEC Montréal (HEC Montréal), UMR1383, Immuno-Endocrinologie Cellulaire et Moléculaire, Institut National de la Recherche Agronomique (INRA), Génétique Physiologie et Systèmes d'Elevage (GenPhySE ), Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Vétérinaire de Toulouse (ENVT), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-École nationale supérieure agronomique de Toulouse [ENSAT], Génétique Expérimentale en Productions Animales (GEPA), Entrepôts, Représentation et Ingénierie des Connaissances (ERIC), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Université Lumière - Lyon 2 (UL2), Université Bretagne Loire (UBL), Université de Nantes (UN), Ecole Nationale Vétérinaire Agroalimentaire et de l'Alimentation Nantes Atlantique (ONIRIS), UE 1372 Génétique, Expérimentation et Système Innovants, Institut National de la Recherche Agronomique (INRA)-Génétique animale (G.A.)-Physiologie Animale et Systèmes d'Elevage (PHASE), Institut National de la Recherche Agronomique (INRA)-Génétique, Expérimentation et Système Innovants (GenESI), Université Lumière - Lyon 2 (UL2), Institut National de la Recherche Agronomique (INRA)-Université de Nantes (UN)-Ecole Nationale Vétérinaire de Nantes, Université Lumière - Lyon 2 (UL2)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, École nationale supérieure agronomique de Toulouse [ENSAT]-Institut National de la Recherche Agronomique (INRA)-Ecole Nationale Vétérinaire de Toulouse (ENVT), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées, and Génétique, Expérimentation et Système Innovants (GenESI)
Pig husbandry is known as an intensive breeding system, piglets being submitted to multiple stressful events such as early weaning, successive mixing, crowding and shipping. These stressors are thought to impair immune defences and might contribute, at least partly, to the prophylactic use of antibiotics. Robustness was recently defined as the ability of an individual to express a high-production potential in a wide variety of environmental conditions. Increasing robustness thus appears as a valuable option to improve resilience to stressors and could be obtained by selecting piglets upon their adrenocortical activity. In this study, we aimed at depicting the consequences of an acute social stress on the immune capacity of piglets genetically selected upon divergent hypothalamic-pituitary-adrenocortical (HPA) axis activity. For this purpose, we monitored neuroendocrine and immune parameters, in high- (HPA(hi)) and low- (HPAI(lo)) responders to ACTH, just before and immediately after a one-hour mixing with unfamiliar conspecifics. As expected, stressed piglets displayed higher levels of circulating cortisol and norepinephrine. Blood cell count analysis combined to flow cytometry revealed a stress-induced leukocyte mobilization in the bloodstream with a specific recruitment of CD8 alpha(+) lymphocytes. Besides, one-hour mixing decreased LPS-induced IL-8 and TNF alpha secretions in whole-blood assays (WBA) and reduced mononuclear cell phagocytosis. Altogether, our data demonstrate that acute social stress alters immune competence of piglets from both groups, and bring new insights in favour of good farming practices. While for most parameters high- and low-responders to ACTH behaved similarly, HPA(hi) piglets displayed higher number of CD4(+) CD8 alpha(-) T cells, as well as increased cytokine production in WBA (LPS-induced TNFa and PIL-induced IL-8), which could confer them increased resistance to pathogens. Finally, a principal component analysis including all parameters highlighted that overall stress effects were less pronounced on piglets with a strong HPA axis. Thus, selection upon adrenocortical axis activity seems to reduce the magnitude of response to stress and appears as a good tool to increase piglet robustness.