Jin Wan

New insights into the role of chitosan oligosaccharide in enhancing growth performance, antioxidant capacity, immunity and intestinal development of weaned pigs

Chitosan oligosaccharide (COS), an oligomer of D-glucosamine, is a vital growth stimulant in the pig industry. However, the mechanisms by which COS mediates pig growth are not fully understood. Therefore, we further investigated how COS supplementation affects pig growth. A total of 32 Landrace × Yorkshire weaned pigs were randomly divided into a control group (basal diet without COS supplementation) and a COS group (100 mg COS per kg basal diet). The pigs that ingested COS for 21 days were associated with a higher (P < 0.05) average daily body weight gain compared to those in the control group. Relative to the control group, the apparent digestibility of crude protein, ash, fat, dry matter and gross energy were markedly elevated (P < 0.05) upon COS supplementation. COS supplementation not only increased (P < 0.05) the activities of superoxide dismutase, catalase and total antioxidant capacity but also elevated (P < 0.05) interleukin-6, tumour necrosis factor-α and immunoglobulin G concentrations in the serum. Moreover, the serum malondialdehyde concentration was decreased (P < 0.05) 26.59% by COS ingestion. COS supplementation also significantly enhanced (P < 0.05) secretory immunoglobulin A content, villus height and digestive enzyme activities (maltase, lactase and sucrase) in the small intestine. Intriguingly, dietary COS supplementation up-regulated (P < 0.05) the tight junction protein claudin-1 (CLDN-1) and occludin (OCLN) mRNA abundance, as well as the Na+–glucose co-transporter 1 (SGLT1) mRNA abundance in the jejunum. Importantly, COS not only increased (P < 0.05) the Bifidobacterium populations in the ileum but also decreased (P < 0.05) the total bacteria and Escherichia coli populations in the caecum and colon. Together, these results suggest that COS supplementation can accelerate weaned pig growth through enhancing antioxidant and immune properties, as well as intestinal development.

Expression of a Tandemly Arrayed Plectasin Gene from Pseudoplectania nigrella in Pichia pastoris and its Antimicrobial Activity.

In recent years, various naturally occurring defence peptides such as plectasin have attracted considerable research interest because they could serve as alternatives to antibiotics. However, the production of plectasin from natural microorganisms is still not commercially feasible because of its low expression levels and weak stability. A tandemly arrayed plectasin gene (1,002 bp) from Pseudoplectania nigrella was generated using the isoschizomer construction method, and was inserted into the pPICZαA vector and expressed in Pichia pastoris. The selected P. pastoris strain yielded 143 μg/ml recombinant plectasin (Ple) under the control of the methanol-inducible alcohol oxidase 1 (AOX1) promoter. Ple was estimated by SDS-PAGE to be 41 kDa. In vitro studies have shown that Ple efficiently inhibited the growth of several gram-positive bacteria such as Streptococcus suis and Staphylococcus aureus. S. suis is the most sensitive bacterial species to Ple, with a minimum inhibitory concentration (MIC) of 4 μg/ml. Importantly, Ple exhibited resistance to pepsin but it was quite sensitive to trypsin and maintained antimicrobial activity over a wide pH range (pH 2.0 to 10.0). P. pastoris offers an attractive system for the cost-effective production of Ple. The antimicrobial activity of Ple suggested that it could be a potential alternative to antibiotics against S. suis and S. aureus infections.

Dietary chitosan oligosaccharide supplementation improves foetal survival and reproductive performance in multiparous sows

Chitosan oligosaccharide (COS), a partially hydrolysed product of chitosan, has various important biological activities. In the present study, we explored the effects of dietary COS supplementation on the reproductive performance and gene expression of certain biochemical markers in the placenta and foetus of sows. Fifty-two Yorkshire multiparous sows were randomly allocated into two groups after mating (n = 26) and fed either with a corn–soybean basal diet (CON) or the basal diet supplemented with 100 mg kg−1 COS (COS). We show that COS supplementation significantly enhanced (P < 0.05) the foetal survival rate and size (crown-to-rump length) after 35 days of gestation. COS supplementation also significantly elevated (P < 0.05) the number of viable piglets born per litter and the average weights for piglets born alive. Interestingly, COS supplementation not only elevated (P < 0.05) serum leptin and immunoglobulin (IgG, IgA, and IgM) concentrations but also increased (P < 0.05) the total antioxidant capacity (T-AOC) at 35 days of gestation. Moreover, the serum leptin and IgG concentrations were higher (P < 0.05) in COS than in the CON group at 85 days of gestation. Importantly, dietary COS supplementation not only up-regulated (P < 0.05) the expression levels of leptin and VEGFA in the placenta but also elevated (P < 0.05) the expression of critical foetal development-related genes (STAT3, TGF-β, and FGFR2) in the foetus at 35 days of gestation. Collectively, these results furthered our understanding of the mechanisms underlying the beneficial effects of COS on foetal development and reproductive performance in pregnant sows.

Alginic acid oligosaccharide accelerates weaned pig growth through regulating antioxidant capacity, immunity and intestinal development

Alginic acid oligosaccharide (ALGO) is the lyase–lysate of alginic acid, which is a naturally occurring anionic polysaccharide isolated from the cell walls of seaweed. In the present study, we fully characterised the effects of dietary ALGO supplementation on certain parameters of weaned pigs. In a 21-day experiment, 16 Landrace × Yorkshire weaned pigs were divided into two groups (n = 8) and fed either with a corn–soybean basal diet (CON) or a basal diet supplemented with 100 mg kg−1 ALGO. We show that dietary ALGO supplementation markedly enhanced (P < 0.05) the average daily body weight gain (ADG) of weaned pigs over the experimental periods. ALGO supplementation not only elevated (P < 0.05) the concentrations of IL-10, IgG and IgA but also increased (P < 0.05) the activities of superoxide dismutase (SOD), catalase (CAT) and total antioxidant capacity (T-AOC) in the serum. Moreover, the concentration of serum malonic dialdehyde (MDA) was lower (P < 0.05) in the ALGO group than in the CON group. ALGO supplementation also significantly enhanced (P < 0.05) secretory immunoglobulin A (sIgA) content, villus height and disaccharidase activities (lactase and sucrase) in the small intestine. Interestingly, dietary ALGO supplementation up-regulated (P < 0.05) the expression levels of tight junction protein occludin (OCLN) and zonula occludens 1 (ZO-1) in the small intestine. Importantly, ALGO not only increased (P < 0.05) the populations of Bifidobacterium and Lactobacillus but also decreased (P < 0.05) the populations of total bacteria and Escherichia coli in the intestine. Overall, the positive effects of ALGO on the growth performance, antioxidant capacity, immunity and intestinal development in weaned pigs suggest that ALGO could serve as an attractive bioactive feed additive in the pig industry, which may be beneficial to human health.

Amniotic fluid metabolomics and biochemistry analysis provides novel insights into the diet-regulated foetal growth in a pig model

Foetal loss and intrauterine growth restriction are major problems in mammals, but there are few effective ways in preventing it. Intriguingly, chitosan oligosaccharide (COS), a biomaterial derived from chitosan, can promote foetal survival and growth. Therefore, we have investigated how COS affects foetal survival and growth in a pig model. Fifty-two sows were divided into two treatment groups (n = 26) and fed either solely a control diet or a control diet that includes 100 mg/kg COS. Amniotic fluid and foetus samples from six sows that were of average body weight in each group were collected on gestation day 35. We applied a 1H NMR-based metabolomics approach combined with biochemistry analysis to track the changes that occurred in the amniotic fluid of pregnant sows after COS intervention. Maternal COS inclusion had enhanced (P < 0.05) the foetal survival rate and size at 35 days. COS supplementation had both increased (P < 0.05) SOD, CAT and T-AOC activities and elevated (P < 0.05) IL-10, IgG and IgM concentrations in the amniotic fluid. Moreover, COS had affected (P < 0.05) the amniotic fluid’s lysine, citrate, glucose and hypoxanthine levels. Overall, COS inclusion induced amniotic fluid antioxidant status and metabolic profiles modifications characterising improvements in foetal survival and growth in a pig model.

Effect of dietary chitosan oligosaccharide supplementation on the pig ovary transcriptome

Fecundity improvement is one of the most important economic traits for the swine industry as it significantly increases production efficiency. Intriguingly, chitosan oligosaccharide (COS), a biomaterial with an active amino group, could promote sow reproductive performance. Therefore, we investigated the effects of dietary COS supplementation on the gene expression differences in the ovaries of sows using the RNA-Seq method. This analysis obtained 13 960 051 and 14 564 863 clean reads in control ovary and COS ovary libraries, respectively. A total of 486 differentially expressed genes (DEGs) were thereby identified (FDR ≤ 0.001, |log2 ratio| ≥ 1). There were 234 up-regulated and 252 down-regulated genes in the COS ovary samples compared with the control ovary samples. A large number of these DEGs were involved in the terms cellular process, cell & cell part and binding. Furthermore, pathway analysis indicated that these DEGs were significantly enriched in 34 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, including cell cycle, progesterone-mediated oocyte maturation, metabolic pathways, oocyte meiosis, and hematopoietic cell lineage among others. These results provided the molecular mechanisms of using COS feed additive for improving sow litter size and prolificacy.

Alginate oligosaccharide enhances intestinal integrity of weaned pigs through altering intestinal inflammatory responses and antioxidant status

Alginate oligosaccharide (AOS), prepared from depolymerised alginate, a natural polysaccharide occurring in the cell walls of brown algae, provides beneficial effects for intestinal health. However, the underlying mechanisms by which AOS supplementation maintains the intestinal integrity of weaned pigs remain obscure. Here, we aimed to determine how AOS modulates the intestinal integrity of weaned pigs. Twenty-four weaned pigs were assigned to two treatments: a control group (basal diet) and an AOS group (the basal diet supplemented with 100 mg kg−1 AOS). On day 15, eight pigs per treatment were randomly selected and sacrificed for serum and intestinal samples. We observed that AOS supplementation enhanced the intestinal integrity, as evidenced by the increased (P < 0.05) intestinal occludin protein abundance. Compared to the control group, AOS ingestion both elevated (P < 0.05) the jejunal and ileal catalase activity and decreased (P < 0.05) the duodenal and jejunal tumour necrosis factor-α concentration and mast cell tryptase expression. Furthermore, AOS down-regulated (P < 0.05) the duodenal toll-like receptor 4 (TLR4) and its down-stream signals, myeloid differentiation factor 88 (MyD88), interleukin-1 receptor-associated kinase 1 (IRAK1) and tumour necrosis factor receptor-associated factor 6 (TRAF6) mRNA levels, as well as jejunal nucleotide-binding oligomerisation domain protein 1 (NOD1) and its adaptor molecule, receptor-interacting serine/threonine-protein kinase 2 (RIPK2), mRNA levels. Additionally, phospho-nuclear factor-κB (p-NF-κB) p65 protein abundance in the duodenum and jejunum was down-regulated (P < 0.05) following AOS supplementation. According to the above results, the enhanced intestinal integrity in AOS-supplemented pigs appears to be associated with the elevated antioxidant capacity and the reduced mast cell degranulation, as well as the inhibited pro-inflammatory cytokines production via inhibiting the TLR4/NF-κB and NOD1/NF-κB signalling pathways.

Maternal chitosan oligosaccharide supplementation during late gestation and lactation affects offspring growth

Abstract Chitosan oligosaccharide (COS), a natural compound derived from chitin, has growth promotion property. However, the nature of the relationship between maternal COS supplementation and offspring growth is not yet understood. Therefore, we intended to determine the effects of maternal COS supplementation in late gestation and lactation on the offspring growth performance. Twenty-four pregnant Yorkshire sows were distributed into two equal groups (n = 12) and fed either with a basal diet (control group) or a basal diet containing 100 mg/kg COS, from gestation day 85 until lactation day 21. Serum samples were collected from six sows of average body weight, from each group on farrowing day (lactation day 1) and lactation day 21, whereas colostrum and milk samples were respectively obtained on lactation days 1 and 21. We found that maternal COS supplementation significantly increased (p < .05) the average piglet weaning weight per litter. Supplementation of COS in the sow diet elevated (p < .05) the serum interleukin-10, immunoglobulin A (IgA) and IgM concentrations, as well as total antioxidant capacity. Moreover, higher (p < .05) colostrum IgM and milk lactose contents were simultaneously observed in COS-treated sows compared to the control sows. In summary, COS supplementation during late gestation and lactation can boost antioxidant capacity and humoural immunity of sows, and contributes to improving colostrum and milk quality, ultimately, enhancing the offspring growth performance.

Alginate oligosaccharide alleviates enterotoxigenic Escherichia coli-induced intestinal mucosal disruption in weaned pigs

Alginate oligosaccharide (AOS) is a non-toxic, non-immunogenic, non-carcinogenic and biodegradable product generated by depolymerisation of alginate, and exhibits various salutary properties. The present study was designed to evaluate whether AOS supplementation could attenuate enterotoxigenic Escherichia coli (ETEC)-induced intestinal mucosal injury in weaned pigs. Twenty-four weaned pigs were randomly assigned to three treatments: (1) non-challenged control; (2) ETEC-challenged control; and (3) ETEC challenge + AOS treatment (100 mg kg-1). On day 12, pigs in the non-challenged group were orally infused with sterilised Luria-Bertani culture while pigs in other groups were orally infused with ETEC (2.6 × 1011 colony-forming units). At 3 days after the challenge, all pigs were orally administered d-xylose at 0.1 g per kg body weight and then euthanised 1 h later to obtain serum and intestinal mucosa samples. Our results showed that ETEC infection both reduced (P < 0.05) the villus height and proportion of epithelial cells in the S phase and elevated (P < 0.05) the percentage of total apoptotic epithelial cells in the jejunum and ileum; these deleterious effects caused by ETEC were alleviated (P < 0.05) by supplemental AOS. Meanwhile, AOS ingestion attenuated (P < 0.05) not only the up-regulated tumour necrosis factor receptor 1 (TNFR1), cysteinyl aspartate-specific protease-3 (caspase-3), -8 and -9 transcriptions, as well as the enhanced caspase activities (caspase-3, -8 and -9), but also the down-regulated cyclin E1 and cyclin-dependent kinase 2 (CDK2) transcriptions in jejunal and ileal mucosae, caused by the ETEC challenge. In conclusion, it is possible that the protective effects of AOS against ETEC-induced intestinal mucosal disruption in weaned pigs are associated with the restrained enterocyte death, by reducing both mitochondria-dependent and TNFR1-dependent apoptosis and the accelerated enterocyte proliferation, via enhancing the cyclin E-CDK2 complex formation.