On the importance of the stress mediators in the control of immunity

En élevage intensif, les porcs sont exposés à de nombreux facteurs de stress qui pourraient favoriser la survenue d’infections et contribuer à l’utilisation massive d’antibiotiques. Les facteurs de stress activent principalement l’axe hypothalamo-hypophyso-surrénalien et l’axe sympatho-adréno-médullaire qui contribuent au retour à l’état d’équilibre. Les médiateurs de ces deux axes, les glucocorticoïdes et les catécholamines, peuvent moduler les réponses immunitaires d’un individu. Dans ce contexte, les objectifs de ma thèse étaient de décrire (i) les effets d’un stress social aigu chez des porcelets forts et faibles répondeurs à une stimulation à l’ACTH sur des paramètres immunitaires et (ii) les effets des catécholamines sur les macrophages porcins. Un mélange de loge durant 1h avec des congénères non familiers induit une mobilisation leucocytaire mais altère la plupart des fonctions immunitaires analysées. Si la majorité des paramètres immunitaires testés ne diffère pas entre les porcelets des 2 groupes, les porcelets avec un axe corticotrope fort semblent plus résilients au stress ce qui encourage à poursuivre cette stratégie de sélection génétique pour produire des porcs robustes. Les effets des catécholamines sur les macrophages ont ensuite été étudiés plus spécifiquement in vitro. L’activation du récepteur β2-adrénergique affecte la sécrétion de cytokines pro-inflammatoires induite par le LPS et diminue l’expression des marqueurs pro-inflammatoires par les macrophages. L’ensemble des résultats obtenus avec des approches in vivo et in vitro devrait permettre une meilleure compréhension des relations entre stress et immunité chez le porc.In intensive husbandry, pigs are exposed to multiple stressful events, which are thought to impair immune defences and may contribute to the prophylactic use of antibiotics. Stressors mainly activate hypothalamo-pituitary-adrenocortical (HPA) and sympatho-adreno-medullar axes, which both contribute to restore homeostasis. Glucocorticoids and catecholamines are mediators of these two pathways and may modulate immune responses. In this context, my PhD project aimed (i) to describe acute social stress effects on immune traits in piglets high and low responders to ACTH stimulation and (ii) to analyze catecholamine effects on porcine macrophages in vitro. One-hour mixing with unfamiliar conspecifics increases leucocyte mobilization and affects most of tested immune functions. Although most immune parameters do not differ between piglets from both groups, stress effects were less pronounced in piglets with a strong HPA axis. Thus, selecting piglets with a strong HPA axis seems a valuable tool to produce robust animals. Catecholamine effects were then more specifically studied on macrophages in vitro. β2-adrenergic receptor activation affects LPS-induced pro-inflammatory cytokine secretion and decreases pro-inflammatory marker expression in porcine macrophages. Altogether these data obtained using in vivo and in vitro experiments should allow a better understanding of the relationships between stress and immunity in pigs

Myostatin deficiency is associated with an increase in number of total axons and motor axons innervating mouse tibialis anterior muscle

Contact: [email protected] audienceINTRODUCTION: Myostatin (Mstn) is a secreted protein that acts as a negative regulator of skeletal muscle mass. However, a critical evaluation of neuromuscular aspects of hypertrophied muscles induced by Mstn deficiency has not been done. METHODS: We compared the tibialis anterior musclenerve interrelationships in wild-type and Mstn-null mice of both genders by immunohistochemical analyses, which allowed us to count the number of total axons and motor axons and estimate the size of motor units and the innervation ratio of the tibialis anterior muscle (TAm). RESULTS: There was an increase in the number of total axons and motor axons, and higher values in both the motor unit size and the innervation ratio of Mstn-null TAm compared with those of wild-type TAm. CONCLUSIONS: We found that myostatin is involved either directly in the control of neuromuscular interrelationships or indirectly through its effect on muscle size

Dietary Oxidative Distress: A Review of Nutritional Challenges as Models for Poultry, Swine and Fish

The redox system is essential for maintaining cellular homeostasis. When redox homeostasis is disrupted through an increase of reactive oxygen species or a decrease of antioxidants, oxidative distress occurs resulting in multiple tissue and systemic responses and damage. Poultry, swine and fish, raised in commercial conditions, are exposed to different stressors that can affect their productivity. Some dietary stressors can generate oxidative distress and alter the health status and subsequent productive performance of commercial farm animals. For several years, researchers used different dietary stressors to describe the multiple and detrimental effects of oxidative distress in animals. Some of these dietary challenge models, including oxidized fats and oils, exposure to excess heavy metals, soybean meal, protein or amino acids, and feeding diets contaminated with mycotoxins are discussed in this review. A better understanding of the oxidative distress mechanisms associated with dietary stressors allows for improved understanding and evaluation of feed additives as mitigators of oxidative distress

beta 2-adrenoreceptor stimulation dampens the LPS-induced M1 polarization in pig macrophages

The cross-talk between sympatho-adreno-medullar axis and innate immunity players was mainly studied in rodents. In intensive husbandry, pigs are exposed to multiple stressors inducing repeated releases of catecholamines that bind to adrenoreceptors (AR) on target cells. Among adrenoreceptors, the (beta 2-AR is largely expressed by immune cells including macrophages. We report herein on the effects of catecholamines, through (beta 2-AR stimulation, on pig macrophage functions activated by LPS. beta 2-AR stimulation of porcine macrophages prevented the LPS-induced increase in TINF alpha and IL-8 secretion while increasing IL-10 secretion. In contrast, treatment with a beta 2-agonist had no effect on anti-microbial functions. Lastly, beta 2-AR stimulation of macrophages reduced the expression of genes up regulated by LPS. Altogether, we demonstrated that (beta 2-AR stimulation of porcine macrophages prevented polarization towards a pro-inflammatory phenotype. Since porcine macrophages are a suitable model for human macrophages, our results might be relevant to appreciate catecholamine effects on human macrophages

Beta 2-adrenergic stimulation of dendritic cells favors IL-10 secretion by CD4(+) T cells

Adrenergic receptor agonists and antagonists are extensively used as drugs in medicine for a broad spectrum of indications. We examined the consequences of beta 2-adrenergic stimulation of murine dendritic cells (DCs) on CD4(+) T cell activation. We demonstrated in vitro that treatment of LPS-matured DCs with the beta 2-agonist salbutamol reduced their ability to trigger OT-II T cell proliferation specific for ovalbumin antigen. Salbutamol also induced a decrease in MHC class II molecule expression by DC through Gi protein activation. Co-culture of CD4(+) T cells with salbutamol-conditioned mature DC impaired TNF alpha and IL-6 secretion while preserving IL-10 production by T cells. Using a vaccination protocol in mice, we showed that salbutamol favored IL-10-producing CD4(+) T cells. None of these effects was observed when working with beta 2-adrenoreceptor deficient mice. Finally, we suggest that beta 2-adrenergic stimulation of DC could be an interesting way to shape CD4(+) T cell responses for the purposes of immunotherapy

beta 2-adrenoreceptor stimulation dampens the LPS-induced M1 polarization in pig macrophages

The cross-talk between sympatho-adreno-medullar axis and innate immunity players was mainly studied in rodents. In intensive husbandry, pigs are exposed to multiple stressors inducing repeated releases of catecholamines that bind to adrenoreceptors (AR) on target cells. Among adrenoreceptors, the (beta 2-AR is largely expressed by immune cells including macrophages. We report herein on the effects of catecholamines, through (beta 2-AR stimulation, on pig macrophage functions activated by LPS. beta 2-AR stimulation of porcine macrophages prevented the LPS-induced increase in TINF alpha and IL-8 secretion while increasing IL-10 secretion. In contrast, treatment with a beta 2-agonist had no effect on anti-microbial functions. Lastly, beta 2-AR stimulation of macrophages reduced the expression of genes up regulated by LPS. Altogether, we demonstrated that (beta 2-AR stimulation of porcine macrophages prevented polarization towards a pro-inflammatory phenotype. Since porcine macrophages are a suitable model for human macrophages, our results might be relevant to appreciate catecholamine effects on human macrophages

Effects of divergent selection upon adrenocortical activity on immune traits in pig

Abstract Background The sustainability of farming and animal welfare requires the reconsideration of current selection schemes. In particular, implementation of new selection criteria related to animal health and welfare should help to produce more robust animals and to reduce anti-microbial use. The hypothalamo-pituitary-adrenocortical (HPA) axis plays a major role in metabolic regulation and adaptation processes and its activity is strongly influenced by genetic factors. A positive association between HPA axis activity and robustness was recently described. To explore whether selecting pigs upon HPA axis activity could increase their robustness, a divergent selection experiment was carried out in the Large White pig breed. This allowed the generation of low (HPAlo) and high (HPAhi) responders to adrenocorticotropic hormone administration. Results In this study, we compared 23 hematologic and immune parameters of 6-week-old, HPAlo and HPAhi piglets and analysed their response to a low dose of lipopolysaccharide (LPS) two weeks later. At six weeks of age, HPAhi piglets displayed greater red blood cell and leucocyte number including CD8α+ γδ cells, cytotoxic T lymphocytes, naive T helper (Th) cells and B lymphocytes as compared to HPAlo individuals. The ability of blood cells to secrete TNFα in response to LPS ex vivo was higher for HPAhi pigs. At week eight, the inflammatory response to the LPS in vivo challenge was poorly affected by the HPA axis activity. Conclusions Divergent selection upon HPA axis activity modulated hematologic and immune parameters in 6-week-old pigs, which may confer an advantage to HPAhi pigs at weaning. However, HPAlo and HPAhi piglets did not exhibit major differences in the parameters analysed two weeks later, i. e. in 8-week-old pigs. In conclusion, chronic exposure to high cortisol levels in HPAhi pigs does not negatively impact immunity

DDR1 and DDR2 physical interaction leads to signaling interconnection but with possible distinct functions

<p>Discoidin domain receptors 1 and 2 (DDR1 and DDR2) are members of the tyrosine kinase receptors activated after binding with collagen. DDRs are implicated in numerous physiological and pathological functions such as proliferation, adhesion and migration. Little is known about the expression of the two receptors in normal and cancer cells and most of studies focus only on one receptor. Western blot analysis of DDR1 and DDR2 expression in different tumor cell lines shows an absence of high co-expression of the two receptors suggesting a deleterious effect of their presence at high amount. To study the consequences of high DDR1 and DDR2 co-expression in cells, we over-express the two receptors in HEK 293T cells and compare biological effects to HEK cells over-expressing DDR1 or DDR2. To distinguish between the intracellular dependent and independent activities of the two receptors we over-express an intracellular truncated dominant-negative DDR1 or DDR2 protein (DDR1DN and DDR2DN). No major differences of Erk or Jak2 activation are found after collagen I stimulation, nevertheless Erk activation is higher in cells co-expressing DDR1 and DDR2. DDR1 increases cell proliferation but co-expression of DDR1 and DDR2 is inhibitory. DDR1 but not DDR2 is implicated in cell adhesion to a collagen I matrix. DDR1, and DDR1 and DDR2 co-expression inhibit cell migration. Moreover a DDR1/DDR2 physical interaction is found by co-immunoprecipitation assays. Taken together, our results show a deleterious effect of high co-expression of DDR1 and DDR2 and a physical interaction between the two receptors.</p

Extracellular hemoglobin combined with an O 2 ‐generating material overcomes O 2 limitation in the bioartificial pancreas: Extracellular hemoglobin combined with an O-2-generating material overcomes O-2 limitation in the bioartificial pancreas

ISI Document Delivery No.: HR1SX Times Cited: 1 Cited Reference Count: 61 Moure, Anne Bacou, Elodie Bosch, Steffi Jegou, Dominique Salama, Apolline Riochet, David Gauthier, Olivier Blancho, Gilles Soulillou, Jean-Paul Poncelet, Denis Olmos, Eric Bach, Jean-Marie Mosser, Mathilde Bosch, Steffi/A-1557-2009 Bosch, Steffi/0000-0002-0995-2775; Moure, Anne/0000-0002-1891-3698 Agence Nationale de la Recherche (ECTIS IHU program, France) [ANR-10-IBHU-005]; Pays de la Loire Region (Xenothera program, Nantes, France) [2011-1296]; University of Nantes (Interdisciplinary program, Nantes, France) [2017-2203] Agence Nationale de la Recherche (ECTIS IHU program, France), Grant/Award Number: ANR-10-IBHU-005; Pays de la Loire Region (Xenothera program, Nantes, France), Grant/Award Number: 2011-1296; University of Nantes (Interdisciplinary program, Nantes, France), Grant/Award Number: 2017-2203 1 4 15 Wiley Hoboken 1097-0290International audienceThe bioartificial pancreas encapsulating pancreatic islets in immunoprotective hydrogel is a promising therapy for Type 1 diabetes. As pancreatic islets are highly metabolically active and exquisitely sensitive to hypoxia, maintaining O-2 supply after transplantation remains a major challenge. In this study, we address the O-2 limitation by combining silicone-encapsulated CaO2 (silicone-CaO2) to generate O-2 with an extracellular hemoglobin O-2-carrier coencapsulated with islets. We showed that the hemoglobin improved by 37% the O-2-diffusivity through an alginate hydrogel and displayed antioxidant properties neutralizing deleterious reactive O-2 species produced by silicone-CaO2. While the hemoglobin alone failed to maintain alginate macroencapsulated neonate pig islets under hypoxia, silicone-CaO2 alone or combined to the hemoglobin restored islet viability and insulin secretion and prevented proinflammatory metabolism (PTGS2 expression). Interestingly, the combination took the advantages of the two individual strategies, improved neonate pig islet viability and insulin secretion in normoxia, and VEGF secretion and PDK1 normalization in hypoxia. Moreover, we confirmed the specific benefits of the combination compared to silicone-CaO2 alone on murine pseudo-islet viability in normoxia and hypoxia. For the first time, our results show the interest of combining an O-2 provider with hemoglobin as an effective strategy to overcome O-2 limitations in tissue engineering

Acute social stress-induced immunomodulation in pigs high and low responders to ACTH

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