Organic Selenium Increased Gilts Antioxidant Capacity, Immune Function, and Changed Intestinal Microbiota

Abstract

Selenium is an indispensable essential micronutrient for humans and animals, and it can affect biological functions by combining into selenoproteins. The purpose of this study was to investigate the effects of 2-hydroxy-4-methylselenobutanoic acid (HMSeBA) on the antioxidant performance, immune function, and intestinal microbiota composition of gilts. From weaning to the 19th day after the second estrus, 36 gilts (Duroc × Landrace × Yorkshire) were assigned to three treatments: control group, sodium selenite group (0.3 mg Se/kg Na₂SeO₃), and HMSeBA group (0.3 mg Se/kg HMSeBA). Dietary supplementation with HMSeBA improved the gilts tissue selenium content (except in the thymus) and selenoprotein P (SelP1) concentration when compared to the Na₂SeO₃ or control group. Compared with the control group, the antioxidant enzyme activity in the tissues from gilts in the HMSeBA group was increased, and the concentration of malondialdehyde in the colon had a decreasing trend (p = 0.07). Gilts in the HMSeBA supplemented group had upregulated gene expression of GPX2, GPX4, and SelX in spleen tissue, TrxR1 in thymus; GPX1 and SelX in duodenum, GPX3 and SEPHS2 in jejunum, and GPX1 in the ileum tissues (p < 0.05). In addition, compared with the control group, the expression of interleukin-1β (IL-1β), interleukin-6 (IL-6), interleukin-8 (IL-8), and monocyte chemotactic protein-1 (MCP-1) in the liver, spleen, thymus, duodenum, ileum, and jejunum of gilts in the HMSeBA group were downregulated (p < 0.05), while the expression of interleukin-10 (IL-10) and transforming growth factor-β (TGF-β) in the liver, thymus, jejunum, and ileum were upregulated (p < 0.05). Compared with the control group and the Na₂SeO₃ group, HMSeBA had increased concentration of serum cytokines interleukin-2 (IL-2) and immunoglobulin G (IgG; p < 0.05), increased concentration of intestinal immunoglobulin A (sIgA; p < 0.05), and decreased concentration of serum IL-6 (p < 0.05). Dietary supplementation with HMSeBA also increased the abundance of intestinal bacteria (Ruminococcaceae and Phascolarctobacterium; p < 0.05) and selectively inhibited the abundance of some bacteria (Parabacteroides and Prevotellaceae; p < 0.05). In short, HMSeBA improves the antioxidant performance and immune function of gilts, and changed the structure of the intestinal microflora. And this study provided data support for the application of HMSeBA in gilt and even pig production.

Keywords: 2-hydroxy-4-methylselenobutanoic acid; antioxidant capacity; gilts; immune function; intestinal microbiota.

Figure 1

The effect of HMSeBA on the expression of selenoprotein related genes in spleen (A) and thymus (B) of gilts. n = 5 in each group. Data were shown as means ± SE. n = 5 in each group. Control, basal diet; Na₂SeO₃, 0.3 mg Se/kg Na₂SeO₃; HMSeBA, 0.3 mg Se/kg HMSeBA. ^a,b,cMean values within a row with different superscript letters were significantly different (p < 0.05). SelP1, selenoprotein P; GPX, glutathione peroxidase; TrxR, thioredoxin reductase; SelK, selenoprotein K; SelS, selenoprotein S; SelX, selenoprotein X; SEPHS2, selenophosphate synthetase 2.

Figure 2

The effect of HMSeBA on the expression of selenoprotein related genes in duodenum (A), jejunum (B), and ileum (C) of gilts. n = 5 in each group. Data were shown as means ± SE. n = 5 in each group. Control, basal diet; Na₂SeO₃, 0.3 mg Se/kg Na₂SeO₃; HMSeBA, 0.3 mg Se/kg HMSeBA. ^a,b,cMean values within a row with different superscript letters were significantly different (p < 0.05). SelP1, selenoprotein P; GPX, glutathione peroxidase; TrxR, thioredoxin reductase; SelK, selenoprotein K; SelS, selenoprotein S; SelX, selenoprotein X; SEPHS2, selenophosphate synthetase 2.

Figure 3

The effect of HMSeBA on the expression of related cytokines in the liver (A), spleen (B), and thymus (C) of gilts. n = 5 in each group. Data were shown as means ± SE. n = 5 in each group. Control, basal diet; Na₂SeO₃, 0.3 mg Se/kg Na₂SeO₃; HMSeBA, 0.3 mg Se/kg HMSeBA. ^a,b,cMean values within a row with different superscript letters were significantly different (p < 0.05). IL-1β, interleukin-1β; IL-6, interleukin-6; IL-8, interleukin-8; IL-10, interleukin-10; TNF-α, tumor necrosis factor-α; TGF-β, transforming growth factor-β; IFN-β, interferon-β; ICAM-1, intercellular cell adhesion molecule-1; MCP-1, monocyte chemotactic protein-1; INOS-2, inducible nitric oxide synthase-2.

Figure 4

The effect of HMSeBA on the expression of related cytokines in duodenum (A), jejunum (B), and ileum (C) of gilts. n = 5 in each group. Data were shown as means ± SE. n = 5 in each group. Control, basal diet; Na₂SeO₃, 0.3 mg Se/kg Na₂SeO₃; HMSeBA, 0.3 mg Se/kg HMSeBA. ^a,b,cMean values within a row with different superscript letters were significantly different (p < 0.05). IL-1β, interleukin-1β; IL-6, interleukin-6; IL-8, interleukin-8; IL-10, interleukin-10; TNF-α, tumor necrosis factor-α; TGF-β, transforming growth factor-β; IFN-β, interferon-β; ICAM-1, intercellular cell adhesion molecule-1; MCP-1, monocyte chemotactic protein-1; INOS-2, inducible nitric oxide synthase-2.

Figure 5

Heat map of correlation analysis between serum cytokines and microorganisms at the phylum level. S.IL2: serum IL-2; S.IL6: serum IL-6; S.TNF: serum TNF-α. n = 5. Spearman diagram showed that the ordinate was environmental factor information, and the abscess was species information. The value corresponding to the middle heat map was Spearman correlation coefficient r, which was between −1 and 1. r < 0 was negative correlation, r> was positive correlation, and the marker * indicated p < 0.05 for significance test.

Figure 6

Heat map of correlation analysis between serum cytokines and microorganisms at the genus level. S.IL2: serum IL-2; S.IL6: serum IL-6 S.TNF: serum TNF-α. n = 5. Spearman diagram showed that the ordinate was environmental factor information, and the abscess was species information. The value corresponding to the middle heat map was Spearman correlation coefficient r, which was between −1 and 1. r < 0 was negative correlation, r> was positive correlation, and the marker * indicated p < 0.05 for significance test.