Stress and immunity in poultry: light management and nanotechnology as effective immune enhancers to fight stress

Abstract

The poultry industry plays a significant role in boosting the economy of several countries, particularly developing countries, and acts as a good, cheap, and affordable source of animal protein. A stress-free environment is the main target in poultry production. There are several stressors, such as cold stress, heat stress, high stocking density, and diseases that can affect birds and cause several deleterious changes. Stress reduces feed intake and growth, as well as impairs immune response and function, resulting in high disease susceptibility. These effects are correlated with higher corticosteroid levels that modulate several immune pathways such as cytokine-cytokine receptor interaction and Toll-like receptor signaling along with induction of excessive production of reactive oxygen species (ROS) and thus oxidative stress. Several approaches have been considered to boost bird immunity to overcome stress-associated effects. Of these, dietary supplementation of certain nutrients and management modifications, such as light management, are commonly considered. Dietary supplementations improve bird immunity by improving the development of lymphoid tissues and triggering beneficial immune modulators and responses. Since nano-minerals have higher bioavailability compared to inorganic or organic forms, they are highly recommended to be included in the bird's diet during stress. Additionally, light management is considered a cheap and safe approach to control stress. Changing light from continuous to intermittent and using monochromatic light instead of the normal light improve bird performance and health. Such changes in light management are associated with a reduction of ROS production and increased antioxidant production. In this review, we discuss the impact of stress on the immune system of birds and the transcriptome of oxidative stress and immune-related genes, in addition, how nano-minerals supplementations and light system modulate or mitigate stress-associated effects.

Keywords: Immune stimulant; Immunity; Light management; Nanoparticles; Poultry; Stress.

Fig. 1

Stress-associated modulation of the hypothalamic-pituitary-adrenal axis and immune response by the central nervous system. Stress triggers a series of hormonal releases. For example, the stress-associated increased level of corticosteroids induces several immune pathways (e.g., cytokine-cytokine receptor interaction and the Toll-like receptor signaling pathways). Together, these reactions lead to impaired immune function and high levels of immune mediators such as interleukins. ACTH, adrenocorticotropic hormone; CRH, corticotropin-releasing hormone; GH, growth hormone; IFN, interferon; IL, interleukin; PRL, prolactin; TGFβ4, transforming growth factor beta 4. (Figure created using BioRender.com)

Fig. 2

Induction of oxidative stress by, e.g., cold or heat stressors. Oxidative stress triggers Nrf2/ARE signaling and NF-κB and eventually induces antioxidant protein expression and inflammatory response and apoptosis. ARE, antioxidant response element; BAX, BCL2 associated X; CASP8, caspase-8; CAT, catalase; G6PD, glucose 6 phosphate dehydrogenase; GCLC and GCLM, glutamate cysteine ligase catalytic and regulatory subunits; GPx, glutathione peroxidase-1; GST, glutathione S-transferase; HO-1, heme oxygenase-1; HSP, heat shock proteins; IFN, interferon; IL, interleukin; iNOS, inducible nitric oxide synthase; Keap1, Kelch-like ECH-associated protein 1; NF-κB, nuclear factor kappa light-chain enhancer of activated B cells; NQO-1, NAD(P)H quinone oxidoreductase-1; Nrf2, Nuclear factor erythroid 2 (NF-E2)-related factor 2; PGES, prostaglandin E synthase; ROS, reactive oxygen species; sMaf, small musculoaponeurotic fibrosarcoma; SOD, superoxide dismutase; TGF1β, transforming growth factor beta 1; UDPGT, uridine diphosphate glucuronosyltransferase