Immunomodulation by diet : individual differences in sensitivity in layer hens

Enhancing relevant immunity of production animals to achieve more robust animals is receiving more and more attention. Several epidemics have hit production animals recently and with devastating consequences, but enhancing diseases resistance increasingly provides new opportunities. Furthermore, welfare and health of production animals is becoming a more and more consumer driven topic. Several routes are being used to approach the possibility of enhancing immunity such as selective breeding, enriched and altered housing conditions, vaccination programs, diet supplementation with immune stimulating components, and other management procedures. Disease susceptibility has been shown to be related to stress reactivity, which in turn is related to differences in HPA axis reactivity. Interestingly, independent of selection criteria used, the extremes of various selection procedures result in a recurrent dichotomy in HPA axis reactivity, either being hyperresponsive or hyporesponsive to stress. Animals with a hyperresponsive HPA axis show greater environmental sensitivity, while the hyporeactive animals are more intrinsically regulated. Often, research on immunomodulation is performed with compromised animals and/or exaggerated supplementation of dietary components in one generation of animals, but epigenetics by definition seems to be the mechanism for mothers to prepare their offspring for the environment they will be born into. Enhancing immunity through normal diet in uncompromised animals is rarely investigated, let alone over generations. In this thesis the aim was to induce immunomodulation through diet in selection lines of chicken that have previously been selected on their antibody response to sheep red blood cells over two generations of chicken. First, potential HPA axis differences were examined in these selection lines to establish their environmental sensitivity, whereafter immunomodulation through normal diet was investigated in humoral and cellular parameters of immunity. As humoral immunocompentence was not easily modulated, an immune trigger was used to detect potential differences in humoral reactivity. The selection lines showed differential sensitivity to immunomodulation by diet in both generations, suggesting that adaptation to environmental factors may be a line-specific (genetically based) process, with differential neuroendocrine regulation. Most interestingly, the second generation showed effects of the diets in all the selection lines, albeit in different manners. It is concluded that normal diet can cause immunomodulation, mainly in animals with hyper HPA axis reactivity, and that introducing such practices may be more beneficial when mothers are treated, as all offspring showed immunomodulation, irrespective of selection line. While genetic background and/or epigenetic processes on neuroendocrine and immune regulation of the individual form the framework wherein individual immunomodulation by diet can take place, environmental conditions determine if the modulation is beneficial or not. <br/

Stress induced polarization of immune-neuroendocrine phenotypes in Gallus gallus

Immune-neuroendocrine phenotypes (INPs) stand for population subgroups differing in immune-neuroendocrine interactions. While mammalian INPs have been characterized thoroughly in rats and humans, avian INPs were only recently described in Coturnix coturnix (quail). To assess the scope of this biological phenomenon, herein we characterized INPs in Gallus gallus (a domestic hen strain submitted to a very long history of strong selective breeding pressure) and evaluated whether a social chronic stress challenge modulates the individuals’ interplay affecting the INP subsets and distribution. Evaluating plasmatic basal corticosterone, interferon-γ and interleukin-4 concentrations, innate/acquired leukocyte ratio, PHA-P skin-swelling and induced antibody responses, two opposite INP profiles were found: LEWIS-like (15% of the population) and FISCHER-like (16%) hens. After chronic stress, an increment of about 12% in each polarized INP frequency was found at expenses of a reduction in the number of birds with intermediate responses. Results show that polarized INPs are also a phenomenon occurring in hens. The observed inter-individual variation suggest that, even after a considerable selection process, the population is still well prepared to deal with a variety of immune-neuroendocrine challenges. Stress promoted disruptive effects, leading to a more balanced INPs distribution, which represents a new substrate for challenging situations.Fil: Nazar, Franco Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Estevez, Inma. Centro de Investigación. Neiker - Tecnalia; EspañaFil: Correa, Silvia Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Córdoba. Centro de Investigaciones en Bioquímica Clínica e Inmunología; ArgentinaFil: Marin, Raul Hector. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; Argentin

Chicken lines selected for their primary antibody response to sheep red blood cells show differential hypothalamic-pituitary-adrenal axis responsiveness to mild stressors

The interaction between the neuroendocrine system and the immune system is well established and supports their mutually affecting relationship. Many animal selection lines have been created according to individual behavioral or neuroendocrine responses to stress. Here we present 2 chicken lines selected for 25 generations for their primary antibody response to immunization with SRBC, as well as the control line from the same parental strain. In the first experiment, the blood-sampling procedure caused a mild stress response, with the expected increase in plasma corticosterone levels. In a second experiment, group housing caused the expected increase in corticosterone levels. In both experiments, the hens of the low line showed the greatest increase in corticosterone levels to our 2 mild stressors. Our results show that birds selected throughout 25 generations for an immune parameter show different HPA axis responsivenes

Chicken lines divergently selected for antibody responses to sheep red blood cells show line-specific differences in sensitivity to immunomodulation by diet. Part I: Humoral parameters

Individual differences in nutrient sensitivity have been suggested to be related with differences in stress sensitivity. Here we used layer hens divergently selected for high and low specific antibody responses to SRBC (i.e., low line hens and high line hens), reflecting a genetically based differential immune competence. The parental line of these hens was randomly bred as the control line and was used as well. Recently, we showed that these selection lines differ in their stress reactivity; the low line birds show a higher hypothalamic-pituitary-adrenal (HPA) axis reactivity. To examine maternal effects and neonatal nutritional exposure on nutrient sensitivity, we studied 2 subsequent generations. This also created the opportunity to examine egg production in these birds. The 3 lines were fed 2 different nutritionally complete layer feeds for a period of 22 wk in the first generation. The second generation was fed from hatch with the experimental diets. At several time intervals, parameters reflecting humoral immunity were determined such as specific antibody to Newcastle disease and infectious bursal disease vaccines; levels of natural antibodies binding lipopolysaccharide, lipoteichoic acid, and keyhole limpet hemocyanin; and classical and alternative complement activity. The most pronounced dietary-induced effects were found in the low line birds of the first generation: specific antibody titers to Newcastle disease vaccine were significantly elevated by 1 of the 2 diets. In the second generation, significant differences were found in lipoteichoic acid natural antibodies of the control and low line hens. At the end of the observation period of egg parameters, a significant difference in egg weight was found in birds of the high line. Our results suggest that nutritional differences have immunomodulatory effects on innate and adaptive humoral immune parameters in birds with high HPA axis reactivity and affect egg production in birds with low HPA axis reactivit

Sensitivity of innate and adaptive cellular immune parameters of poultry to minor macro- and micronutrient differences in two nutritionally complete layer feeds

Comparable diets were found to modulate levels of specific and natural humoral immunity in different manners over two generations of genetically selected hens for a high or low Ab response. These diets were based on ingredients that were grown organically (diet A) or conventionally (diet B). Here we report the effects of these diets on cellular immune parameters such as monocyte reactivity measured by NO production, proliferation of whole blood leucocytes and PBMC with the T- and B-cell mitogens, ConA and LPS respectively. Furthermore we measured the in vitro modulatory effects of water soluble extracts of the two diets on T-cell proliferation of whole blood cultures. In both generations a feed change enhanced monocyte reactivity in all birds with the high line birds being most sensitive. Whole blood assays showed the most pronounced diet effects on T-cell reactivity. The low line birds of the first generation showed the greatest effect, but in the second generation all lines were affected by the diets. In the PBMC the greatest effects were found in the control values, with the effects differing in each generation. The present results together with the results found in the whole blood cultures, suggest dietary effects on the intrinsic reactivity of peripheral lymphocytes as well as in vivo effects, the first with quickly measurable effects and the last activity reflected in our later measurements. These results suggest that a feed change with only minor nutritional differences will induce immunomodulatory effects, and each diet has a unique effect on cellular parameters of innate and adaptive immunity