Safety evaluation of 3'-siallylactose sodium salt supplementation on growth and clinical parameters in neonatal piglets

The human milk oligosaccharide 3'sialyllactose reduces low-grade inflammation and atherosclerosis development in mice

Macrophages contribute to the induction and resolution of inflammation and play a central role in chronic low-grade inflammation in cardiovascular diseases caused by atherosclerosis. Human milk oligosaccharides (HMOs) are complex unconjugated glycans unique to human milk that benefit infant health and act as innate immune modulators. Here, we identify the HMO 3'sialyllactose (3'SL) as a natural inhibitor of TLR4-induced low-grade inflammation in macrophages and endothelium. Transcriptome analysis in macrophages revealed that 3'SL attenuates mRNA levels of a selected set of inflammatory genes and promotes the activity of liver X receptor (LXR) and sterol regulatory element binding protein-1 (SREBP1). These acute antiinflammatory effects of 3'SL were associated with reduced histone H3K27 acetylation at a subset of LPS-inducible enhancers distinguished by preferential enrichment for CCCTC-binding factor (CTCF), IFN regulatory factor 2 (IRF2), B cell lymphoma 6 (BCL6), and other transcription factor recognition motifs. In a murine atherosclerosis model, both s.c. and oral administration of 3'SL significantly reduced atherosclerosis development and the associated inflammation. This study provides evidence that 3'SL attenuates inflammation by a transcriptional mechanism to reduce atherosclerosis development in the context of cardiovascular disease.

Effects of 3'-Sialyllactose on Symptom Improvement in Patients with Knee Osteoarthritis: A Randomized Pilot Study

Background/Objectives: 3'-Sialyllactose (3'-SL), a human milk oligosaccharide, has anti-inflammatory effects and is demonstrated to have protective effects against osteoarthritis (OA) in vitro and in vivo. However, this hypothesis remains to be investigated in a clinical setting. Herein, we investigated the effects of 3'-SL on pain and physical function in patients with knee OA. Methods: Sixty patients with knee OA with Kellgren and Lawrence grades (KL-grades) 1-4 and Korean Western Ontario and McMaster Universities Osteoarthritis Index (KWOMAC) scores ≥30 were randomly assigned to the placebo (n = 20), 3'-SL 200 mg (n = 20), and 3'-SL 600 mg (n = 20) groups. For 12 weeks, 3'-SL or placebo was administered to patients once a day. Clinical efficacy was evaluated using a visual analog scale (VAS) for pain and KWOMAC for physical function at baseline and at 6 and 12 weeks. Adverse effects were assessed for 12 weeks. Results: Significant reductions in VAS and KWOMAC scores were observed at 12 weeks compared with the baseline in the 3'-SL group. No severe adverse effects were observed over 12 weeks. Conclusions: 3'-SL reduced pain in patients with knee OA, improved daily life movements, and was safe, suggesting that 3'-SL might be an effective treatment for knee OA without severe side effects.

Potential biological functions and future perspectives of sialylated milk oligosaccharides

Sialyllactoses (SLs) primarily include sialylated human milk oligosaccharides (HMOs) and bovine milk oligosaccharides (BMOs). First, the safety assessment of 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL) revealed low toxicity in various animal models and human participants. SLs constitute a unique milk component, highlighting the essential nutrients and bioactive components crucial for infant development, along with numerous associated health benefits for various diseases. This review explores the safety, biosynthesis, and potential biological effects of SLs, with a specific focus on their influence across various physiological systems, including the gastrointestinal system, immune disorders, rare genetic disorders (such as GNE myopathy), cancers, neurological disorders, cardiovascular diseases, diverse cancers, and viral infections, thus indicating their therapeutic potential.

More than nutrition: Therapeutic potential and mechanism of human milk oligosaccharides against necrotizing enterocolitis

Human milk is the most valuable source of nutrition for infants. The structure and function of human milk oligosaccharides (HMOs), which are key components of human milk, have long been attracting particular research interest. Several recent studies have found HMOs to be efficacious in the prevention and treatment of necrotizing enterocolitis (NEC). Additionally, they could be developed in the future as non-invasive predictive markers for NEC. Based on previous findings and the well-defined functions of HMOs, we summarize potential protective mechanisms of HMOs against neonatal NEC, which include: modulating signal receptor function, promoting intestinal epithelial cell proliferation, reducing apoptosis, restoring intestinal blood perfusion, regulating microbial prosperity, and alleviating intestinal inflammation. HMOs supplementation has been demonstrated to be protective against NEC in both animal studies and clinical observations. This calls for mass production and use of HMOs in infant formula, necessitating more research into the safety of industrially produced HMOs and the appropriate dosage in infant formula.

Dietary supplementation of 3'-sialyllactose or 6'-sialyllactose elicits minimal influence on cognitive and brain development in growing pigs

Sialylated human milk oligosaccharides (HMO), such as 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL), are abundant throughout lactation and at much higher concentrations than are present in bovine milk or infant formulas. Previous studies have suggested that sialylated HMO may have neurocognitive benefits in early life. Recent research has focused on infant formula supplementation with key nutrients and bioactives to narrow the developmental gap between formula-fed and breastfed infants. Herein, we investigated the impact of supplemental 3'-SL or 6'-SL on cognitive and brain development at two time-points [postnatal days (PND) 33 and 61]. Two-day-old piglets (N = 75) were randomly assigned to commercial milk replacer ad libitum without or with 3'-SL or 6'-SL (added in a powdered form at a rate of 0.2673% on an as-is weight basis). Cognitive development was assessed via novel object recognition and results were not significant at both time-points (p > 0.05). Magnetic resonance imaging was used to assess structural brain development. Results varied between scan type, diet, and time-point. A main effect of diet was observed for absolute volume of white matter and 9 other regions of interest (ROI), as well as for relative volume of the pons on PND 30 (p < 0.05). Similar effects were observed on PND 58. Diffusion tensor imaging indicated minimal differences on PND 30 (p > 0.05). However, several dietary differences across the diffusion outcomes were observed on PND 58 (p < 0.05) indicating dietary impacts on brain microstructure. Minimal dietary differences were observed from myelin water fraction imaging at either time-point. Overall, sialyllactose supplementation had no effects on learning and memory as assessed by novel object recognition, but may influence temporally-dependent aspects of brain development.

Determining the safety and efficacy of dietary supplementation with 3'-sialyllactose or 6'-sialyllactose on growth, tolerance, and brain sialic acid concentrations

Sialylated oligosaccharides, including 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL), comprise a large portion of human milk and have been known to support development over the first year of life. While research has investigated the impact of early-life supplementation, longer-term supplementation remains relatively unexplored. Consequently, the following study assesses the impact of supplementation of either 3'-SL or 6'-SL on growth performance, tolerance, and brain sialic acid concentrations. Two-day-old piglets (n = 75) were randomly assigned to a commercial milk replacer ad libitum without or with 3'-SL or 6'-SL (added at 0.2673% on an as-is basis). Daily body weight and feed disappearance were recorded to assess growth performance and tolerance. Pigs were euthanized for sample collection on postnatal day 33 (n = 30) or 61 (n = 33), respectively. Across growth performance, clinical chemistry and hematology, histomorphology, and sialic acid quantification, dietary differences were largely unremarkable at either time-point. Overall, SA was well-tolerated both short-term and long-term.

Recent progress on health effects and biosynthesis of two key sialylated human milk oligosaccharides, 3'-sialyllactose and 6'-sialyllactose

Human milk oligosaccharides (HMOs), the third major solid component in breast milk, are recognized as the first prebiotics for health benefits in infants. Sialylated HMOs are an important type of HMOs, accounting for approximately 13% of total HMOs. 3'-Sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL) are two simplest sialylated HMOs. Both SLs display promising prebiotic effects, especially in promoting the proliferation of bifidobacteria and shaping the gut microbiota. SLs exhibit several health effects, including antiadhesive antimicrobial ability, antiviral activity, prevention of necrotizing enterocolitis, immunomodulatory activity, regulation of intestinal epithelial cell response, promotion of brain development, and cognition improvement. Both SLs have been approved as "Generally Recognized as Safe" by the American Food and Drug Administration and are commercially added to infant formula. The biosynthesis of SLs using enzymatic or microbial approaches has been widely studied. The enzymatic synthesis of SLs can be realized by two types of enzymes, sialidases with trans-sialidase activity and sialyltransferases. Microbial synthesis can be achieved by the multiple recombinant bacteria in one-pot reaction, which express the enzymes involved in SL synthesis pathways separately or in combination, or by metabolically engineered strains in a fermentation process. In this article, the physiological properties of 3'-SL and 6'-SL are summarized in detail and the biosynthesis of these SLs via enzymatic and microbial synthesis is comprehensively reviewed.

Efficient Production of a Functional Human Milk Oligosaccharide 3'-Sialyllactose in Genetically Engineered Escherichia coli

3'-Sialyllactose (3'-SL) is one of the most important and simplest sialylated human milk oligosaccharides. In this study, a plasmid-based pathway optimization along with chromosomal integration strategies was applied for 3'-SL production. Specifically, the precursor CMP-Neu5Ac synthesis pathway genes and α2,3-sialyltransferase-encoding gene were introduced into Escherichia coli BL21(DE3)ΔlacZ to realize 3'-SL synthesis. Genes nanA and nanK involved in Neu5Ac catabolism were further deleted to reduce the metabolic flux of competitive pathway. Several α2,3-sialyltransferases from different species were selected to evaluate the sialylation effect. The precursor pools were balanced and improved by optimizing key enzyme expression involved in the UDP-GlcNAc and CMP-Neu5Ac synthesis pathway. Finally, an additional α2,3-sialyltransferase expression cassette was integrated into chromosome to maximize 3'-SL synthesis, and 4.5 g/L extracellular 3'-SL was produced at a shake-flask level. The extracellular 3'-SL concentration was raised to 23.1 g/L in a 5 L bioreactor fermentation, which represents the highest extracellular value ever reported.

Evaluation of the Safety of a Plant-Based Infant Formula Containing Almonds and Buckwheat in a Neonatal Piglet Model

A randomized neonatal piglet trial was conducted to evaluate the safety and the effects of a plant-based formula containing almonds and buckwheat as the main ingredients on growth and plasma parameters. From postnatal day (PND) 2 to 21, the piglets were fed a dairy-based milk formula (Similac Advance) or a plant-based formula (Else Nutrition) and all piglets were euthanized at day 21. No diarrhea was observed after PND 8 and all the piglets completed the trial. Body growth, kcal intake, the complete plasma count parameters and hematological parameters were within the reference range in both groups. Organ growth and development was similar between the two groups. Plasma glucose was higher in the dairy-based-fed piglets relative to the plant-based at 2 weeks of age. Liver function biomarkers levels were greater in the plasma of the plant-based compared to the dairy-based fed group. In addition, calcium levels were higher in the plant-based fed piglets at 1 week of age. Thus, the plant-based formula tested in this study was well tolerated by the piglets and supported similar growth compared to dairy-based milk formula. Therefore, the results support the safety of the tested plant-based infant formula during the neonatal period in comparison to the dairy-based formula fed group.

Randomized, triple-blind, placebo-controlled study to evaluate the safety of 6'-Sialyllactose in healthy adults

Sialyllactoses (SL) are an abundant component of human milk. There have been many studies on the biological effects of SL in humans. SL can be produced using an economical method of enzyme synthesis. Although the European Food Safety Authority has published the human safety and appropriate intake dose of 6'-SL sodium salt as a novel food, it has suggested that the appropriate dose for particular medical purposes be judged on a case-by-case basis. Also, as revealed in the same report, there are no data on toxicity when 6'-SL is used in human intervention. However, clinical studies have only confirmed the safety of 3'-SL for therapeutic intervention in humans, and the safety for therapeutic use of 6'-SL, which is more abundant than 3'-SL in human milk, has not been confirmed. In this study, to determine the safety of 6'-SL use in humans, participants were randomly assigned to the placebo (maltodextrin) and 6'-SL groups, and then 3 g of powder was orally administered twice a day for 12 weeks. There were no serious adverse reactions, such as life-threatening complications requiring hospitalization, causing disability, or causing deformity during the use of 6'-SL. There were no clinically significant differences among the baseline, sixth, and twelfth week clinical chemistry tests, such as aspartate aminotransferase, alanine aminotransferase, and creatinine. Most of the adverse reactions were gastrointestinal problems such as diarrhea, abdominal discomfort, and bloating, with no significant difference in the proportions between the placebo and 6'-SL groups. These results support the safety of the 6'-SL for human use.

Anti-Angiogenic Property of Free Human Oligosaccharides

Angiogenesis, a fundamental process in human physiology and pathology, has attracted considerable attention owing to its potential as a therapeutic strategy. Vascular endothelial growth factor (VEGF) and its receptor (VEGFR) are deemed major mediators of angiogenesis. To date, inhibition of the VEGF-A/VEGFR-2 axis has been an effective strategy employed in the development of anticancer drugs. However, some limitations, such as low efficacy and side effects, need to be addressed. Several drug candidates have been discovered, including small molecule compounds, recombinant proteins, and oligosaccharides. In this review, we focus on human oligosaccharides as modulators of angiogenesis. In particular, sialylated human milk oligosaccharides (HMOs) play a significant role in the inhibition of VEGFR-2-mediated angiogenesis. We discuss the structural features concerning the interaction between sialylated HMOs and VEGFR-2 as a molecular mechanism of anti-angiogenesis modulation and its effectiveness in vivo experiments. In the current state, extensive clinical trials are required to develop a novel VEGFR-2 inhibitor from sialylated HMOs.

Role of Human Milk Bioactives on Infants' Gut and Immune Health

Exclusive human milk feeding of the newborn is recommended during the first 6 months of life to promote optimal health outcomes during early life and beyond. Human milk contains a variety of bioactive factors such as hormones, cytokines, leukocytes, immunoglobulins, lactoferrin, lysozyme, stem cells, human milk oligosaccharides (HMOs), microbiota, and microRNAs. Recent findings highlighted the potential importance of adding HMOs into infant formula for their roles in enhancing host defense mechanisms in neonates. Therefore, understanding the roles of human milk bioactive factors on immune function is critical to build the scientific evidence base around breastfeeding recommendations, and to enhance positive health outcomes in formula fed infants through modifications to formulas. However, there are still knowledge gaps concerning the roles of different milk components, the interactions between the different components, and the mechanisms behind health outcomes are poorly understood. This review aims to show the current knowledge about HMOs, milk microbiota, immunoglobulins, lactoferrin, and milk microRNAs (miRNAs) and how these could have similar mechanisms of regulating gut and microbiota function. It will also highlight the knowledge gaps for future research.

A safety evaluation of mixed human milk oligosaccharides in neonatal farm piglets

Human Milk Oligosaccharides (HMOs) are the third most abundant, solid component of human milk after lactose and fat. As novel processes are developed to cost-effectively produce commercial volumes of these oligosaccharides, they are becoming more common components of infant formulas worldwide. The study evaluated the safety of a novel mixture of HMOs in a neonatal piglet model with the objective of identifying potential effects during the sensitive, preweaning developmental stage of life. The mixture of HMOs (HMO MIX 1) was composed of 2′-fucosyllactose (2′-FL), 3-fucosyllactose (3-FL), lacto-N-tetraose (LNT), 3′-sialyllactose (3′-SL), and 6′-sialyllactose (6′-SL), and was administered to 2-day old piglets at either 5.75 or 8.0 g/L for a period of 21 days. Piglets in the 5.75 and 8.0 g/L HMO MIX 1 dosing groups did not exhibit differences in body weight, food consumption, or feed efficiency. Analysis of clinical chemistry parameters on Study Day 7 and Study Day 21 did not demonstrate any effects that could be attributed to HMO MIX 1, nor were there any findings in organ weight, macroscopic, or microscopic inspection of tissues that could be attributed to this oligosaccharide blend. Therefore, since administration of HMO MIX 1 in a liquid diet up to 8.0 g/L resulted in no toxicologically-relevant effects in comparison with animals fed a control diet, this study supports the safety of this ingredient for addition to infant formula products.

Evaluation of 6'-Sialyllactose Sodium Salt Supplementation to Formula on Growth and Clinical Parameters in Neonatal Piglets

Oligosaccharides are complex, non-digestible glycans found in large abundance in human milk. The abundance and the profile of bovine milk oligosaccharides and bovine milk based in infant formula differ from those in human milk. Recently, some human milk oligosaccharides (HMOs) have been supplemented to infant formula, however, not all forms have been available in large scale. The objective of the study was to investigate the dose-dependent effects of an enzymatically-synthesized 6′-sialyllactose (6′-SL) sodium salt supplemented to swine milk replacer on growth, hematological parameters, and organ microscopic assessment in our pre-clinical neonatal pig model. Two-day-old male and female pigs (n = 47) were provided one of four experimental diets for 21 days. Diets were formulated to contain 0 (CON), 300 (LOW), 600 (MOD), or 1200 (HIGH) mg/L of 6′-SL sodium salt. On days 8 and 22, samples were collected for hematological and histological analyses. Supplemental 6′-SL sodium salt at all doses supported growth and development comparable to those observed in control animals. In addition, serum chemistries, hematology, and organ microscopic structure were unaffected by 6′-SL (p > 0.05). Thus, addition of enzymatically-synthesized 6′-SL to a milk replacer formula supported growth and clinical outcomes similar to the control formula in the neonatal piglet.

A safety evaluation of mixed human milk oligosaccharides in rats

Human milk oligosaccharides (HMOs) are indigestible carbohydrates representing the third largest fraction of solutes in human breastmilk. They provide valuable prebiotic and anti-pathogenic functions in breastfed infants, but are not yet included in most infant formula products. Recent biotechnological advances now facilitate large-scale production of HMOs, providing infant formula manufacturers with the ability to supplement their products with HMOs to mimic human breastmilk. Although the safety of individual HMOs has been confirmed in preclinical toxicological studies, the safety of HMO mixtures has not been tested. We therefore performed bacterial reverse mutation and in vitro micronucleus tests and conducted a repeated-dose oral toxicity study in rats with a mixture of five HMOs (HMO MIX I), containing 2'-fucosyllactose (2'-FL), 3-fucosyllactose (3-FL), lacto-N-tetraose (LNT), 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL). HMO MIX I was not genotoxic and did not induce adverse effects in the repeated dose study. The no-observed-adverse-effect-level (NOAEL) for HMO MIX I in this study is 10% in the diet (equivalent to 5.67 g HMO MIX I/kg bw/day for males and 6.97 g HMO MIX I/kg bw/day for females). Our results provide strong evidence for the safety of HMO MIX I in infant products and general foods.