Dietary polyunsaturated fatty acids from flaxseed affect immune responses of dairy sheep around parturition

Association of Melatonin Administration in Pregnant Ewes with Growth, Redox Status and Immunity of Their Offspring

Simple Summary

Melatonin is a known antioxidant and anti-inflammatory regime, while in sheep it is broadly used to accelerate the onset of the breeding season. Our recent study showed that melatonin administration during pregnancy in heat-stressed ewes improved fertility rate and number of lambs born per ewe, the redox status of the maternal organism and the produced milk quantity until weaning. In this study, we present the impact of melatonin administration in stressed ewes during pregnancy considering: (a) humoral response of both maternal organism and offspring during the first two days after parturition, (b) chemical composition and antioxidant parameters of colostrum and milk until weaning and (c) redox status of the offspring until weaning. The results indicated that melatonin improved the redox status of the offspring and the quality of colostrum. Moreover, melatonin could be administered as immune-modulatory regime, apart from antioxidant, in prenatally stressed offspring in order to cope with the crucial first days of their life, as the humoral response results suggested.

Abstract

In this study, the effects of melatonin treatment on growth, redox status and immunity in prenatally stressed newborn lambs were evaluated. Thirty-seven newborn lambs were allocated into two groups (melatonin-MEL and control-CON), based on whether their mothers were treated with melatonin implants or not, respectively. All pregnant ewes were exposed to heat stress. The body weight of lambs was recorded at birth (L0), and then on days 15 (L15) and 40 (L40). Redox biomarkers [total antioxidant capacity (TAC), glutathione (GSH), thiobarbituric acid reactive substances (TBARS)] were assayed in blood samples collected from lambs on days L0, L1, L2, L5, L10 and L40. Chemical analysis and antioxidant capacity were evaluated in colostrum and milk samples collected at the same time points with blood samples. Cytokines (IL-1β, IL-6, IL-10, IFN-γ) and immunoglobulin (IgG) were assayed in blood and colostrum samples collected from ewes on days L0 and L1, and in lambs’ blood on days L0, L1 and L2. The results revealed that body weight gain of newborn lambs did not differ between the two groups (p > 0.05). Better redox status was found in MEL lambs until L2, as well as higher antioxidant capacity in the colostrum of MEL ewes compared to CON ones on day L0 (p < 0.05). In MEL ewes’ colostrum, higher protein content was measured on day L0 and higher fat content on L1 compared to CON group (p < 0.05). The highest level of IL-6 was found in MEL ewes on L1, with a concomitant increase of IL-10 level in MEL lambs in comparison to CON lambs on L2. Moreover, CON colostrum resulted in a higher level of IL-10 within time, coupled with an increased level of IgG found in lambs’ plasma on L2 (p = 0.04). This study indicated that melatonin could be administered as antioxidant and immune-modulatory regime in prenatally stressed offspring in order to cope with the crucial first days of their life. This effect of melatonin was also amplified by crosstalk between IL-6, IL-10 and IgG production, resulting in an improved quality of produced milk.

Effects of in vitro exposure of sheep ovarian tissue to zearalenone and matairesinol on preantral follicles

The aim of this study was to evaluate the effect of 1 µmol/l zearalenone (ZEN) and 1 µmol/l matairesinol (MAT), alone or in combination, on the morphology of in vitro-cultured ovarian preantral follicles. Ovaries from four adult sheep were collected at a local slaughterhouse and fragmented, and the ovarian pieces were submitted to in vitro culture for 3 days in the presence or absence of the test compounds. The morphology of primordial and primary follicles was impaired by ZEN. The plant lignan MAT alone did not maintain the morphology of the ovarian follicles; its combination with ZEN counteracted the negative effects observed when follicles were cultured in the presence of the mycotoxin alone. However, MAT was not able to promote the in vitro development of the ovarian follicles.

Transcriptome Adaptation of the Ovine Mammary Gland to Dietary Supplementation of Extruded Linseed

Several dietary strategies were adopted to reduce saturated fatty acids and increase beneficial fatty acids (FA) for human health. Few studies are available about the pathways/genes involved in these processes. Illumina RNA-sequencing was used to investigate changes in the ovine mammary gland transcriptome following supplemental feeding with 20% extruded linseed. Comisana ewes in mid-lactation were fed a control diet for 28 days (control period) followed by supplementation with 20% DM of linseed panel for 28 days (treatment period). Milk production was decreased by 30.46% with linseed supplementation. Moreover, a significant reduction in fat, protein and lactose secretion was also observed. Several unsaturated FAs were increased while short and medium chain saturated FAs were decreased by linseed treatment. Around four thousand (1795 up- and 2133 down-regulated) genes were significantly differentially regulated by linseed supplementation. The main pathways affected by linseed supplementation were those involved in the energy balance of the mammary gland. Principally, the mammary gland of fed linseed sheep showed a reduced abundance of transcripts related to the synthesis of lipids and carbohydrates and oxidative phosphorylation. Our study suggests that the observed decrease in milk saturated FA was correlated to down-regulation of genes in the lipid synthesis and lipid metabolism pathways.

NETosis of Peripheral Neutrophils Isolated From Dairy Cows Fed Olive Pomace

Neutrophils represent primary mobile phagocytes recruited to the site of infection, and their functions are essential to enhance animals' health performance. Neutrophils have an essential role in innate immunity and are able to kill the pathogens via the synthesis of neutrophil extracellular traps (NETs). The objective of the present work was the study of the in vitro NETosis of peripheral neutrophils isolated from dairy cows supplemented with olive pomace. Dairy cows (n = 16) balanced for parity (3.67 ± 1.5 for CON, 3.67 ± 1.9 for OP), milk yield (24.3 ± 4.5 kg d⁻¹for CON and 24.9 ± 1.7 kg d⁻¹ for OP), the number of days in milk (109 ± 83.5 for CON and 196 ± 51 for OP), and body weight (647 ± 44.3 kg for CON and 675 ± 70.7 kg for OP) were divided into two experimental groups fed with a control diet (CON) and supplemented with 6% of olive pomace (OP). Peripheral blood neutrophils were isolated and stimulated in vitro with phorbol-myristate-acetate (PMA) as a marker for activation and reactivity of the neutrophils. After isolation, both the viability and CD11b expression were analyzed by flow cytometry. Both NETosis by neutrophil elastase-DNA complex system and myeloperoxidase (MPO) activity were evaluated by ELISA. The specific antibodies against MPO and citrullination of Histone-H1 were used for investigating NETosis by immunofluorescence microscopy. The neutrophil elastase-DNA complexes produced during NETosis and MPO activity of neutrophil extracts were affected by OP supplementation. Furthermore, results from immunofluorescence analysis of NETosis depicted a similar result found by ELISA showing a higher expression of MPO and citrullination of Histone-H1 in OP than the CON neutrophils. In addition, all data showed that the OP diet resulted in a better response of neutrophils to PMA stimulation than the CON diet, which did not support the neutrophils' responses to PMA stimulation. Our results demonstrated that OP supplementation can enhance the neutrophil function in dairy cows leading to udder defense and inflammation response especially when an immunosuppression state can occur.

Micronutrients and bioactive compounds in the immunological pathways related to SARS-CoV-2 (adults and elderly)

The new coronavirus pandemic is affecting the entire world with more than 25 million confirmed cases in August 2020 according to the World Health Organization. It is known that the virus can affect several tissues and can progress to a respiratory failure in severe cases. To prevent the progression to this stage of the disease and minimize all the damage caused by coronavirus (SARS-CoV-2) the immune system must be in its integrity. A healthy nutritional status are fundamental to efficient immunological protection and consequently a good response to SARS-CoV-2. Micronutrients and bioactive compounds perform functions in immune cells that are extremely essential to stop SARS-CoV-2. Their adequate consumption is part of a non-pharmacological intervention to keep the immune system functioning. This review has as main objective to inform how micronutrients and bioactive compounds could act in the essential immunological pathways could stop SARS-CoV-2, focusing on the functions that have already established in the literature and transposing to this scenario.

Maternal supplementation with fish oil modulates inflammation-related MicroRNAs and genes in suckling lambs

Dietary n-3 long-chain fatty acids (n-3 LCFA) have been shown to modify lipid metabolism and immune function. The objective of this study was to evaluate the effect of periparturient fish oil (FO) supplementation on the inflammation and metabolic health of ewes and their lambs at a molecular level. Prepartum ewes were fed control diet (CON, n = 12) or CON supplemented with 2% DM of calcium soap of FO (n = 12) from 28 days before until 21 days after parturition. The ewes were evaluated for plasma metabolites and milk composition. The experiment was followed by analyzing the relative transcript abundance of circulating microRNAs (miRNAs) in plasma and targeted miRNA/mRNA expression in peripheral blood mononuclear cells (PBMCs) in both ewes and lambs. FO treatment decreased prepartum feed intake (1812 ± 35 vs 1674 ± 33 g/day, P < 0.01), whereas the influence on plasma metabolites was negligible. Dietary FO supplementation decreased milk fat percentage (8.82 ± 0.49 vs 7.03 ± 0.45, P = 0.02) and reduced milk n-6/n-3 (P < 0.05). Also, it altered the expression of plasma-circulating miRNAs in both ewe and lamb (P < 0.05). Furthermore, maternal nutrition of FO downregulated the relative expression of miR-33a and miR-146b and transcript abundance of genes IL-1β (0.41-fold) and NF-κB (0.25-fold) in lambs' PBMC. In conclusion, results showed that FO supplementation starting antepartum affects milk composition and circulating miRNA in dams and the inflammatory markers in lambs delivered by the supplemented ewes. These may provide a strategy to maintain immune balance during gestation and develop the immune system in lambs.

Extracts from Microalga Chlorella sorokiniana Exert an Anti-Proliferative Effect and Modulate Cytokines in Sheep Peripheral Blood Mononuclear Cells

The objective of this experiment was to study the effects of the unsaponified fraction (UP), the acetylated unsaponified fraction (AUP), and the total lipid fraction (TL) extracted and purified from Chlorella sorokiniana (CS) on the proliferation and cytokine profile of sheep peripheral blood mononuclear cells (PBMCs). Cells were cultured with 0.4 mg/mL and 0.8 mg/mL concentrations of each extract (UP, AUP, and TL fractions) and activated with 5 μg/mL concanavalin A (ConA) and 1 μg/mL lipopolysaccharide (LPS) at 37 °C for 24 h. PBMCs cultured with ConA and LPS represented the stimulated cells (SC), and PBMCs without ConA and LPS represented the unstimulated cells (USC). Cell-free supernatants were collected to determine IL-10, IL-1β, and IL-6 secretions; on cells, measurement of proliferation was performed. All the extracts tested significantly decreased the cell proliferation; in particular, the UP fraction at 0.4 mg/mL showed the lowest proliferative response. Furthermore, at 0.8 mg/mL, the UP fraction enhanced IL-10 secretion. On the contrary, the TL fraction at 0.4 mg/mL induced an increase in IL-10, IL-6, and, to a lesser extent, IL-1β secretions by cells. The AUP fraction did not change cytokine secretion. The results demonstrated that CS extracts could be useful ingredients in animal feed in order to minimize the use of antibiotics by modulating cell proliferation and cytokine response.

Phytosterols from Dunaliella tertiolecta Reduce Cell Proliferation in Sheep Fed Flaxseed during Post Partum

The post partum period is characterized by immunosuppression and increased disease susceptibility. Both phytosterols from microalga Dunaniella tertiolecta and dietary supplementation with n-3 polyunsaturated fatty acids (PUFA) influence cell proliferation and cytokine release during inflammation. The objective of this paper was the evaluation of the effects of physterols, extracted and purified from D. tertiolecta, on the in vitro immune responses of ewes supplemented with flaxseed during post partum. Twenty Comisana parturient ewes were divided in two balanced groups, and supplemented with flaxseed (FS, 250 g/day) or fed with a conventional diet (CON). Blood samples (15 mL) were collected for five weeks, starting from lambing, in order to isolate peripheral blood mononuclear cells (PBMC). Stimulated PBMC were treated with a total sterols fraction from D. tertiolecta (TS), a mix of ergosterol and 7-dehydroporiferasterol (purified extract, PE), and a mix of acetylated ergosterol and 7-dehydroporiferasterol (acetylated purified extract, AcPE), extracted and purified from D. tertiolecta at two concentrations (0.4 and 0.8 mg/mL). Results of the experiment demonstrated that n-3 PUFA from flaxseed induced an anti-inflammatory cytokine profile, with an increase of both IL-10, IL-6 and a decrease of IL-1β. TS, PE, and AcPE purified from D. tertiolecta showed an anti-proliferative effect on sheep PBMC regardless their chemical composition and concentration.