Maternal Neu5Ac Supplementation During Pregnancy Improves Offspring Learning and Memory Ability in Rats

Characterization of Bifidobacterium bifidum growth and metabolism on whey protein phospholipid concentrate

Whey protein phospholipid concentrate (WPPC) is a co-product generated during the manufacture of whey protein isolate. Whey protein phospholipid concentrate is depleted of simple sugars but contains numerous glycoconjugates embedded in the milk fat globule membrane, suggesting this fraction may serve as a carbon source for growth of bifidobacteria commonly enriched in breastfed infants. In this work, we demonstrate that WPPC can serve as a sole carbon source for the growth of Bifidobacterium bifidum, a species common to the breastfed infant and routinely used as a probiotic. Growth on WPPC fractions resulted in expression of key extracellular glycosyl hydrolases in B. bifidum associated with the catabolism of glycoproteins. Interestingly, this included induction of fucosidase genes in B. bifidum linked to catabolism of fucosylated human milk oligosaccharides even though the WPPC glycan possesses little fucose. Additional growth studies revealed that WPPC-glycan components N-acetylglucosamine or N-acetylgalactosamine were required for pre-activation of B. bifidum toward rapid growth on fucosylated human milk oligosaccharides. Growth on WPPC fractions also resulted in expression of extracellular sialidases in B. bifidum which promoted a consistent release of sialic acid, a well-known component of bovine milk oligosaccharides and glycoconjugates with potential effects on gut microbial ecology and host cognition. These studies suggest WPPC may serve as a promising bioactive component to facilitate probiotic activity for use in infant formulas and other synbiotic applications.

Efficacy of sialic acid supplementation in early life in autism model rats

Autism spectrum disorder (ASD) is a set of heterogeneous neurodevelopmental conditions, the etiology of which remains elusive. Sialic acid (SA) is an essential nutrient for nervous system development, and previous studies reported that the levels of SA were decreased in the blood and saliva of ASD children. However, it is not clear whether SA supplementation can alleviate behavioral problems in autism. We administered SA intervention in the VPA-induced autism model rats, evaluated behavior performance, and measured the levels of Gne and St8sia2 genes, BDNF and anti-GM1. At the same time, untargeted metabolomics was used to characterize the metabolites. It was found that the stereotypical behaviors, social preference and cognitive function were improved after SA supplementation. Additionally, the number of hippocampal neurons was increased, and the shape was normalized. Moreover, 94 differentially abundant metabolites were identified between the high dose SA and VPA groups. These changes in metabolites were correlated with pyrimidine metabolism, lysine degradation metabolism, biosynthesis of amino acids, mineral absorption, protein digestion and absorption, galactose metabolism, phenylalanine, tyrosine and tryptophan biosynthesis and phenylalanine metabolism. In conclusion, SA could ameliorate ASD-like phenotypes and change metabolites in autistic animals, which suggests that it may be a therapeutic approach for ASD.

Inactivation of the CMAH gene and deficiency of Neu5Gc play a role in human brain evolution

During human evolution, some genes were lost or silenced from the genome of hominins. These missing genes might be the key to the evolution of humans' unique cognitive skills. An inactivation mutation in CMP-N-acetylneuraminic acid hydroxylase (CMAH) was the result of natural selection. The inactivation of CMAH protected our ancestors from some pathogens and reduced the level of N-glycolylneuraminic acid (Neu5Gc) in brain tissue. Interestingly, the low level of Neu5Gc promoted the development of brain tissue, which may have played a role in human evolution. As a xenoantigen, Neu5Gc may have been involved in brain evolution by affecting neural conduction, neuronal development, and aging.

Siglecs-mediated immune regulation in neurological disorders

The surfaces of various immune cells are rich in glycan chains, including the sialic-acid-binding immunoglobulin-like lectins (Siglecs) family. As an emerging glyco-immune checkpoint, Siglecs have the ability to bind and interact with various glycoproteins, thereby eliciting a series of downstream reactions to modulate the immune response. The impact of Siglecs has been extensively studied in tumor immunotherapy. However, research in neurological disorders and neurological diseases is very limited, and therapeutic options involving Siglecs need further exploration. Siglecs play a crucial role in the development, homeostasis, and repair processes of the nervous system, especially in degenerative diseases. This review summarizes studies on the immunomodulatory role mediated by Siglecs expressed on different immune cells in various neurological disorders, elucidates how dysregulated sialic acid contributes to several psychiatric disorders, and discusses the progress and limitations of research on the treatment of neurological disorders.

Role and Mechanism of Sialic Acid in Alleviating Acute Lung Injury through In Vivo and In Vitro Models

Excessive inflammatory reactions are the most important pathological injury factor in acute lung injury (ALI). Our recent study found that sialic acid had an anti-colitis effect. In this study, the effect of sialic acid (SA) on acute lung inflammation was investigated. A lipopolysaccharide (LPS)-induced ALI animal model and LPS-stimulated HUVEC cell model were used to evaluate the anti-inflammatory effect of SA and study its molecular mechanisms. Compared with the LPS group, the lung index of the SA group decreased from 0.79 ± 0.05% to 0.58 ± 0.06% (LPS + 50 SA) and 0.62 ± 0.02% (LPS + 100 SA), with p < 0.01, suggesting that SA could improve the pulmonary edema of mice and alleviate LPS-induced lung injury. Transcriptome research identified 26 upregulated genes and 25 downregulated genes involved in the protection of SA against ALI. These genes are mainly related to the MAPK and NF-κB signaling pathways. Our study also proved that SA markedly downregulated the expression of inflammatory factors and blocked the JNK/p38/PPAR-γ/NF-κB pathway. Meanwhile, SA treatment also upregulated the expression of HO-1 and NQO1 in ALI mice. In vitro, SA obviously repressed the expressions of inflammatory cytokines and the JNK/p38-NF-κB/AP-1 pathway. SA also regulated the expression of oxidative stress-related genes through the Nrf2 pathway. Taken together, SA exhibits a protective role by modulating the anti-inflammatory and anti-oxidation pathways in ALI, and it may be a promising candidate for functional foods to prevent ALI.

Sialic acid in human milk and infant formulas in China: concentration, distribution and type

This study compared the concentrations, types and distributions of sialic acid (SA) in human milk at different stages of the postnatal period with those in a range of infant formulas. Breast milk from mothers of healthy, full-term and exclusively breastfed infants was collected on the 2nd (n 246), 7th (n 135), 30th (n 85) and 90th (n 48) day after birth. The SA profiles of human milk, including their distribution, were analysed and compared with twenty-four different infant formulas. Outcome of this observational study was the result of natural exposure. Only SA of type Neu5Ac was detected in human milk. Total SA concentrations were highest in colostrum and reduced significantly over the next 3 months. Approximately 68·7–76·1 % of all SA in human milk were bound to oligosaccharides. Two types of SA, Neu5Ac and Neu5Gc, have been detected in infant formulas. Most SA was present in infant formulas combined with protein. Breastfed infants could receive more SA than formula-fed infants with the same energy intake. Overall, human milk is a preferable source of SA than infant formulas in terms of total SA content, dynamics, distribution and type. These SA profiles in the natural state are worth to be considered by the production of formulas because they may have a great effect on infant nutrition and development.

Insights into the Structure, Metabolism, Biological Functions and Molecular Mechanisms of Sialic Acid: A Review

Sialic acid (SA) is a kind of functional monosaccharide which exists widely in edible bird's nest (EBN), milk, meat, mucous membrane surface, etc. SA is an important functional component in promoting brain development, anti-oxidation, anti-inflammation, anti-virus, anti-tumor and immune regulation. The intestinal mucosa covers the microbial community that has a significant impact on health. In the gut, SA can also regulate gut microbiota and metabolites, participating in different biological functions. The structure, source and physiological functions of SA were reviewed in this paper. The biological functions of SA through regulating key signaling pathways and target genes were discussed. In summary, SA can modulate gut microbiota and metabolites, which affect gene expressions and exert its biological activities. It is helpful to provide scientific reference for the further investigation of SA in the functional foods.

Recent advances on N-acetylneuraminic acid: Physiological roles, applications, and biosynthesis

N-Acetylneuraminic acid (Neu5Ac), the most common type of Sia, generally acts as the terminal sugar in cell surface glycans, glycoconjugates, oligosaccharides, lipo-oligosaccharides, and polysaccharides, thus exerting numerous physiological functions. The extensive applications of Neu5Ac in the food, cosmetic, and pharmaceutical industries make large-scale production of this chemical desirable. Biosynthesis which is associated with important application potential and environmental friendliness has become an indispensable approach for large-scale synthesis of Neu5Ac. In this review, the physiological roles of Neu5Ac was first summarized in detail. Second, the safety evaluation, regulatory status, and applications of Neu5Ac were discussed. Third, enzyme-catalyzed preparation, whole-cell biocatalysis, and microbial de novo synthesis of Neu5Ac were comprehensively reviewed. In addition, we discussed the main challenges of Neu5Ac de novo biosynthesis, such as screening and engineering of key enzymes, identifying exporters of intermediates and Neu5Ac, and balancing cell growth and biosynthesis. The corresponding strategies and systematic strategies were proposed to overcome these challenges and facilitate Neu5Ac industrial-scale production.

Myristic acid alleviates hippocampal aging correlated with GABAergic signaling

Previous studies have shown that myristic acid (MA), a saturated fatty acid, could promote the proliferation and differentiation of neural stem cells in vitro. However, the effect of MA on hippocampal neurons aging has not been reported in vivo. Here we employed 22-month-old naturally aged C57BL/6 mice to evaluate the effect and mechanism of MA on hippocampal aging. First, we examined a decreased exploration and spatial memory ability in aging mice using the open field test and Morris water maze. Consistently, aging mice showed degenerative hippocampal histomorphology by H&amp;E and Nissl staining. In terms of mechanism, imbalance of GABRB2 and GABRA2 expression in aging mice might be involved in hippocampus aging by mRNA high throughput sequencing (mRNA-seq) and immunohistochemistry (IHC) validation. Then, we revealed that MA alleviated the damage of exploration and spatial memory ability and ameliorated degeneration and aging of hippocampal neurons. Meanwhile, MA downregulated GABRB2 and upregulated GABRA2 expression, indicating MA might alleviate hippocampal aging correlated with GABAergic signaling. In conclusion, our findings revealed MA alleviated hippocampal aging correlated with GABAergic signaling, which might provide insight into the treatment of aging-associated diseases.

Maternal Serum and Placental Metabolomes in Association with Prenatal Phthalate Exposure and Neurodevelopmental Outcomes in the MARBLES Cohort

Prenatal exposure to phthalates, a family of endocrine-disrupting plasticizers, is associated with disruption of maternal metabolism and impaired neurodevelopment. We investigated associations between prenatal phthalate exposure and alterations of both the maternal third trimester serum metabolome and the placental metabolome at birth, and associations of these with child neurodevelopmental outcomes using data and samples from the Markers of Autism Risk in Babies Learning Early Signs (MARBLES) cohort. The third trimester serum (n = 106) and placental (n = 132) metabolomes were investigated using 1H nuclear magnetic resonance spectroscopy. Children were assessed clinically for autism spectrum disorder (ASD) and cognitive development. Although none of the urinary phthalate metabolite concentrations were associated with maternal serum metabolites after adjustment for covariates, mixture analysis using quantile g-computation revealed alterations in placental metabolites with increasing concentrations of phthalate metabolites that included reduced concentrations of 2-hydoxybutyrate, carnitine, O-acetylcarnitine, glucitol, and N-acetylneuraminate. Child neurodevelopmental outcome was not associated with the third trimester serum metabolome, but it was correlated with the placental metabolome in male children only. Maternal phthalate exposure during pregnancy is associated with differences in the placental metabolome at delivery, and the placental metabolome is associated with neurodevelopmental outcomes in males in a cohort with high familial ASD risk.

Concentration and distribution of sialic acid in human milk and its correlation with dietary intake

Purpose

This study evaluates the content, distribution, and changing trend of sialic acid in human milk and the correlation between dietary intake of sialic acid and that in human milk.

Methods

The study included 33 mothers of full-term and exclusively breastfed infants. At least 2 ml of milk was collected on the 3rd, 8th, 30th, and 90th day after delivery, and 24-h diet recalls of the lactating mothers were obtained each time. The correlation of human milk sialic acid concentration with lactating women's dietary sialic acid intake during lactation was analyzed by statistical analysis software SPSS.

Results

The average concentration of sialic acid in colostrum, transition, and 1 and 3 months were 1,670.74 ± 94.53, 1,272.19 ± 128.74, 541.64 ± 55.2, and 297.65 ± 20.78 mg/L, respectively. The total sialic acid concentration in colostrum was about 5.6 times higher than that at 3 months (P < 0.001). The average dietary sialic acid intake of lactating mothers on the 2nd, 7th, 30th, and 90th day after delivery were 106.06 ± 7.51, 127.64 ± 8.61, 120.34 ± 10.21, and 95.40 ± 6.34 mg/day, respectively. The intake of sialic acid was relatively high on the 7th day, and there was no significant difference in dietary intake of sialic acid on different days (P < 0.05). In addition, there was no correlation between the intake of dietary sialic acid and the content of total sialic acid and various forms of sialic acid in milk (P < 0.05).

Conclusion

During the lactation period, the distribution of sialic acid in breast milk is relatively stable and its content fluctuates greatly, which may not be affected by the mother's diet, but mainly depends on the self-regulation oft physiological needs.