Effect of dietary Spirulina (Arthrospira platensis) on the intestinal function of post-weaned piglet: An approach combining proteomics, metabolomics and histological studies.

The effect of dietary Spirulina (Arthrospira platensis) and CAZyme supplementation was assessed on the gut of weaned piglets, using an integrated NMR-metabolomics approach combined with Tandem Mass Tag labelled proteomics. Thirty weaned male piglets were assigned to one of the three following diets (n = 10): cereal and soybean meal basal diet (Control), basal diet with 10% Spirulina inclusion (SP) and SP diet supplemented with 0.01% lysozyme (SP + L). The experiment lasted 4 weeks and, upon slaughter, small intestine samples were collected for histological, metabolomic and proteomic analysis. No significant differences were found for the histology and metabolomics analysis between the three experimental groups. Lactate, glutamate, glycine and myo-inositol were the most abundant metabolites. Proteomics results showed 1502 proteins identified in the intestine tissue. A total of 23, 78, 27 differentially abundant proteins were detected respectively for the SP vs. Control, SP + L vs. Control and SP + L vs. SP comparisons. The incorporation of Spirulina and supplementation of lysozyme in the piglet's diets is associated to intestinal proteomic changes. These include increased protein synthesis and abundance of contractile apparatus proteins, related with increased nutrient availability, which has beneficial (increased glucose uptake) and detrimental (increased digesta viscosity) metabolic effects. SIGNIFICANCE: The use of conventional feedstuffs becomes increasingly prohibitive due to its environmental toll. To increase the sustainability of the livestock sector, novel feedstuffs such as microalgae need to be considered. However, its recalcitrant cell wall has antinutritional effects that can inhibit high dietary inclusion levels. The supplementation with CAZymes is a possible solution to this issue. The small intestine is a central piece in monogastric digestion and of particular importance for the weaned piglet. Studying the effect of dietary Spirulina and CAZyme supplementation on its histomorphology, metabolome and proteome allows studying relevant physiological adaptations to these diets.

Influence of dietary Spirulina inclusion and lysozyme supplementation on the longissimus lumborum muscle proteome of newly weaned piglets.

Arthrospira platensis (Spirulina) is a microalga with a high content of crude protein. It has a recalcitrant cell wall that limits the accessibility of the animal endogenous enzymes to its intracellular nutrients. Enzymatic supplementation aiming to degrade cell walls could benefit microalgae digestibility. The objective of this study was to evaluate the impact of dietary Spirulina and lysozyme supplementation over the muscle proteome of piglets during the post-weaning stage. Thirty piglets were randomly distributed among three diets: control (no microalga), SP (10% Spirulina) and SP + L (10% Spirulina +0.01% lysozyme). After 4 weeks, they were sacrificed and samples of the longissimus lumborum muscle were taken. The muscle proteome was analysed using a Tandem Mass Tag (TMT)-based quantitative approach. A total of 832 proteins were identified. Three comparisons were computed: SP vs Ctrl, SP + L vs Ctrl and SP + L vs SP. They had ten, four and twelve differentially abundant proteins. Glycogen metabolism and nutrient reserves utilization are increased in the SP piglets. Structural muscle protein synthesis increased, causing higher energy requirements in SP + L piglets. Our results demonstrate the usefulness of proteomics to disclose the effect of dietary microalgae, whilst unveiling putative mechanisms derived from lysozyme supplementation. Data available via ProteomeXchange with identifier PXD024083. SIGNIFICANCE: Spirulina, a microalga, is an alternative to conventional crops which could enhance the environmental sustainability of animal production. Due to its recalcitrant cell wall, its use requires additional measures to prevent anti-nutritional effects on the feeding of piglets in the post-weaning period, during which they endure post-weaning stress. One of such measures could be CAZyme supplementation to help degrade the cell wall during digestion. Muscle proteomics provides insightful data on the effect of dietary microalgae and enzyme activity on piglet metabolism.

Metabolome and proteome changes in skeletal muscle and blood of pre-weaning calves fed leucine and threonine supplemented diets.

In pre-weaning calves, both leucine and threonine play important roles in growth and muscle metabolism. In this study, metabolomics, proteomics and clinical chemistry were used to assess the effects of leucine and threonine supplementation added to milk replacer on 14 newborn Holstein male calves: 7 were fed a control diet (Ctrl) and 7 were fed the Ctrl diet supplemented with 0.3% leucine and 0.3% threonine (LT) from 5.6 days of age to 53.6 days. At this time, blood and semitendinosus muscle biopsies were collected for analysis. Integrated metabolomics and proteomics showed that branched-chain amino acids (BCAA) degradation and mitochondrial oxidative metabolism (citrate cycle and respiratory chain) were the main activated pathways in muscle because of the supplementation. BCAA derivatives and metabolites related to lipid mobilization showed the major changes. The deleterious effects of activated oxidative phosphorylation were balanced by the upregulation of antioxidant proteins. An increase in protein synthesis was indicated by elevated aminoacyl-tRNA biosynthesis and increased S6 ribosomal protein phosphorylation in skeletal muscle. In conclusion, LT group showed greater BCAA availability and mitochondrial oxidative activity; as the muscle cells undergo greater aerobic metabolism, antioxidant defenses were activated to compensate for possible cell damage. Data are available via ProteomeXchange (PXD016098). SIGNIFICANCE: Leucine and threonine are essential amino acids for the pre-weaning calf, being of high importance for growth. In this study, we found that leucine and threonine supplementation of milk replacer to feed pre-weaning calves led to differences in the proteome, metabolome and clinical chemistry analytes in skeletal muscle and plasma, albeit no differences in productive performance were recorded. This study extends our understanding on the metabolism in dairy calves and helps optimizing their nutritional status.

High-throughput proteomics and the fight against pathogens.

Pathogens pose a major threat to human and animal welfare. Understanding the interspecies host-pathogen protein-protein interactions could lead to the development of novel strategies to combat infectious diseases through the rapid development of new therapeutics. The first step in understanding the host-pathogen crosstalk is to identify interacting proteins in order to define crucial hot-spots in the host-pathogen interactome, such as the proposed pharmaceutical targets by means of high-throughput proteomic methodologies. In order to obtain holistic insight into the inter- and intra-species bimolecular interactions, apart from the proteomic approach, sophisticated in silico modeling is used to correlate the obtained large data sets with other omics data and clinical outcomes. Since the main focus in this area has been directed towards human medicine, it is time to extrapolate the existing expertise to a new emerging field: the 'systems veterinary medicine'. Therefore, this review addresses high-throughput mass spectrometry-based technology for monitoring protein-protein interactions in vitro and in vivo and discusses pathogen cultivation, model host cells and available bioinformatic tools employed in vaccine development.