Human Milk Oligosaccharide 2′-Fucosyllactose Reduces Neurodegeneration in Stroke Brain

Influence of microbially fermented 2´-fucosyllactose on neuronal-like cell activity in an in vitro co-culture system

Scope

2´-Fucosyllactose (2´-FL), the most abundant oligosaccharide in human milk, plays an important role in numerous biological functions, including improved learning. It is not clear, however, whether 2´-FL or a cleavage product could influence neuronal cell activity. Thus, we investigated the effects of 2´-FL, its monosaccharide fucose (Fuc), and microbial fermented 2´-FL and Fuc on the parameters of neuronal cell activity in an intestinal-neuronal transwell co-culture system in vitro.

Methods

Native 13C-labeled 2´-FL and 13C-Fuc or their metabolites, fermented with Bifidobacterium (B.) longum ssp. infantis and B. breve, which were taken from the lag-, log- and stationary (stat-) growth phases of batch cultures, were applied to the apical compartment of the co-culture system with Caco-2 cells representing the intestinal layer and all-trans-retinoic acid-differentiated SH-SY5Y (SH-SY5YATRA) cells mimicking neuronal-like cells. After 3 h of incubation, the culture medium in the basal compartment was monitored for 13C enrichment by using elemental analysis isotope-ratio mass spectrometry (EA-IRMS) and effects on cell viability, plasma, and mitochondrial membrane potential. The neurotransmitter activation (BDNF, GABA, choline, and glutamate) of SH-SY5YATRA cells was also determined. Furthermore, these effects were also measured by the direct application of 13C-2´-FL and 13C-Fuc to SH-SY5YATRA cells.

Results

While no effects on neuronal-like cell activities were observed after intact 2´-FL or Fuc was incubated with SH-SY5YATRA cells, supernatants from the stat-growth phase of 2´-FL, fermented by B. longum ssp. infantis alone and together with B. breve, significantly induced BDNF release from SH-SY5YATRA cells. No such effects were found for 2´-FL, Fuc, or their fermentation products from B. breve. The BDNF release occurred from an enhanced vesicular release, which was confirmed by the use of the Ca2+-channel blocker verapamil. Concomitant with this event, 13C enrichment was also observed in the basal compartment when supernatants from the stat-growth phase of fermentation by B. longum ssp. infantis alone or together with B. breve were used.

Conclusion

The results obtained in this study suggest that microbial products of 2´-FL rather than the oligosaccharide itself may influence neuronal cell activities.

Efficient production of 2'-fucosyllactose from fructose through metabolically engineered recombinant Escherichia coli

BACKGROUND

The biosynthesis of human milk oligosaccharides (HMOs) using several microbial systems has garnered considerable interest for their value in pharmaceutics and food industries. 2'-Fucosyllactose (2'-FL), the most abundant oligosaccharide in HMOs, is usually produced using chemical synthesis with a complex and toxic process. Recombinant E. coli strains have been constructed by metabolic engineering strategies to produce 2'-FL, but the low stoichiometric yields (2'-FL/glucose or glycerol) are still far from meeting the requirements of industrial production. The sufficient carbon flux for 2'-FL biosynthesis is a major challenge. As such, it is of great significance for the construction of recombinant strains with a high stoichiometric yield.

RESULTS

In the present study, we designed a 2'-FL biosynthesis pathway from fructose with a theoretical stoichiometric yield of 0.5 mol 2'-FL/mol fructose. The biosynthesis of 2'-FL involves five key enzymes: phosphomannomutase (ManB), mannose-1-phosphate guanylytransferase (ManC), GDP-D-mannose 4,6-dehydratase (Gmd), and GDP-L-fucose synthase (WcaG), and α-1,2-fucosyltransferase (FucT). Based on starting strain SG104, we constructed a series of metabolically engineered E. coli strains by deleting the key genes pfkA, pfkB and pgi, and replacing the original promoter of lacY. The co-expression systems for ManB, ManC, Gmd, WcaG, and FucT were optimized, and nine FucT enzymes were screened to improve the stoichiometric yields of 2'-FL. Furthermore, the gene gapA was regulated to further enhance 2'-FL production, and the highest stoichiometric yield (0.498 mol 2'-FL/mol fructose) was achieved by using recombinant strain RFL38 (SG104ΔpfkAΔpfkBΔpgi119-lacYΔwcaF::119-gmd-wcaG-manC-manB, 119-AGGAGGAGG-gapA, harboring plasmid P30). In the scaled-up reaction, 41.6 g/L (85.2 mM) 2'-FL was produced by a fed-batch bioconversion, corresponding to a stoichiometric yield of 0.482 mol 2'-FL/mol fructose and 0.986 mol 2'-FL/mol lactose.

CONCLUSIONS

The biosynthesis of 2'-FL using recombinant E. coli from fructose was optimized by metabolic engineering strategies. This is the first time to realize the biological production of 2'-FL production from fructose with high stoichiometric yields. This study also provides an important reference to obtain a suitable distribution of carbon flux between 2'-FL synthesis and glycolysis.

Transplantation of Exosomes Derived From Human Wharton's Jelly Mesenchymal Stromal Cells Enhances Functional Improvement in Stroke Rats

Cerebral ischemic stroke is a major cerebrovascular disease and the leading cause of adult disability. We and others previously demonstrated that transplantation of human Wharton's jelly mesenchymal stromal cells (WJ-MSCs) attenuated neuronal damage and promoted functional improvement in stroke animals. This study aimed to investigate the protective effects of human WJ-MSC exosome (Exo) transplant in cellular and rat models of cerebral stroke. Administration of Exo significantly antagonized glutamate-mediated neuronal loss and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-X nick end labeling (TUNEL) in rat primary cortical neuronal cultures. Adult male rats underwent a 60-min middle cerebral artery occlusion (MCAo); Exo or vehicle was injected through the tail vein 5-10 min after the MCAo. Two days later, the rats underwent a series of behavioral tests. Stroke rats receiving Exo developed a significant improvement in locomotor function and forelimb strength while reductions in body asymmetry and Bederson's neurological score. After the behavioral test, brain tissues were harvested for histological and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analyses. Animals receiving Exo had less infarction volume, measured by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Transplantation of Exo increased the expression of protective neurotrophic factors (BMP7, GDNF) and anti-apoptotic factors (Bcl2, Bcl-xL) in the ischemic brain. These findings suggest that early post-treatment with WJ-MSC Exo, given non-invasively through the vein, improved functional recovery and reduced brain damage in the stroke brain.

Inhibition of GPR17/ID2 Axis Improve Remyelination and Cognitive Recovery after SAH by Mediating OPC Differentiation in Rat Model

Myelin sheath injury contributes to cognitive deficits following subarachnoid hemorrhage (SAH). G protein-coupled receptor 17 (GPR17), a membrane receptor, negatively regulates oligodendrocyte precursor cell (OPC) differentiation in both developmental and pathological contexts. Nonetheless, GPR17's role in modulating OPC differentiation, facilitating remyelination post SAH, and its interaction with downstream molecules remain elusive. In a rat SAH model induced by arterial puncture, OPCs expressing GPR17 proliferated prominently by day 14 post-onset, coinciding with compromised myelin sheath integrity and cognitive deficits. Selective Gpr17 knockdown in oligodendrocytes (OLs) via adeno-associated virus (AAV) administration revealed that reduced GPR17 levels promoted OPC differentiation, restored myelin sheath integrity, and improved cognitive deficits by day 14 post-SAH. Moreover, GPR17 knockdown attenuated the elevated expression of the inhibitor of DNA binding 2 (ID2) post-SAH, suggesting a GPR17-ID2 regulatory axis. Bi-directional modulation of ID2 expression in OLs using AAV unveiled that elevated ID2 counteracted the restorative effects of GPR17 knockdown. This resulted in hindered differentiation, exacerbated myelin sheath impairment, and worsened cognitive deficits. These findings highlight the pivotal roles of GPR17 and ID2 in governing OPC differentiation and axonal remyelination post-SAH. This study positions GPR17 as a potential therapeutic target for SAH intervention. The interplay between GPR17 and ID2 introduces a novel avenue for ameliorating cognitive deficits post-SAH.

Review on the Impact of Milk Oligosaccharides on the Brain and Neurocognitive Development in Early Life

Milk Oligosaccharides (MOS), a group of complex carbohydrates found in human and bovine milk, have emerged as potential modulators of optimal brain development for early life. This review provides a comprehensive investigation of the impact of milk oligosaccharides on brain and neurocognitive development of early life by synthesizing current literature from preclinical models and human observational studies. The literature search was conducted in the PubMed search engine, and the inclusion eligibility was evaluated by three reviewers. Overall, we identified 26 articles for analysis. While the literature supports the crucial roles of fucosylated and sialylated milk oligosaccharides in learning, memory, executive functioning, and brain structural development, limitations were identified. In preclinical models, the supplementation of only the most abundant MOS might overlook the complexity of naturally occurring MOS compositions. Similarly, accurately quantifying MOS intake in human studies is challenging due to potential confounding effects such as formula feeding. Mechanistically, MOS is thought to impact neurodevelopment through modulation of the microbiota and enhancement of neuronal signaling. However, further advancement in our understanding necessitates clinical randomized-controlled trials to elucidate the specific mechanisms and long-term implications of milk oligosaccharides exposure. Understanding the interplay between milk oligosaccharides and cognition may contribute to early nutrition strategies for optimal cognitive outcomes in children.

Herbal formula PM012 induces neuroprotection in stroke brain

Stroke is a major cause of long-term disability world-wide. Limited pharmacological therapy has been used in stroke patients. Previous studies indicated that herb formula PM012 is neuroprotective against neurotoxin trimethyltin in rat brain, and improved learning and memory in animal models of Alzheimer's disease. Its action in stroke has not been reported. This study aims to determine PM012-mediated neural protection in cellular and animal models of stroke. Glutamate-mediated neuronal loss and apoptosis were examined in rat primary cortical neuronal cultures. Cultured cells were overexpressed with a Ca++ probe (gCaMP5) by AAV1 and were used to examine Ca++ influx (Ca++i). Adult rats received PM012 before transient middle cerebral artery occlusion (MCAo). Brain tissues were collected for infarction and qRTPCR analysis. In rat primary cortical neuronal cultures, PM012 significantly antagonized glutamate-mediated TUNEL and neuronal loss, as well as NMDA-mediated Ca++i. PM012 significantly reduced brain infarction and improved locomotor activity in stroke rats. PM012 attenuated the expression of IBA1, IL6, and CD86, while upregulated CD206 in the infarcted cortex. ATF6, Bip, CHOP, IRE1, and PERK were significantly down-regulated by PM012. Using HPLC, two potential bioactive molecules, paeoniflorin and 5-hydroxymethylfurfural, were identified in the PM012 extract. Taken together, our data suggest that PM012 is neuroprotective against stroke. The mechanisms of action involve inhibition of Ca++i, inflammation, and apoptosis.

Effects of Human Milk Oligosaccharides in Infant Health Based on Gut Microbiota Alteration

The primary active components of breast milk are human milk oligosaccharides (HMOs). HMOs provide many benefits to infants, including regulating their metabolism, immune system, and brain development. Recent studies have emphasized that HMOs act as prebiotics by the metabolism of intestinal microorganisms to produce short-chain fatty acids, which are crucial for infant development. In addition, HMOs with different structural characteristics can form different microbial compositions. HMOs-induced predominant microbes, including Bifidobacterium infantis, B. bifidum, B. breve, and B. longum, and their metabolites demonstrated pertinent health-promoting properties. Meanwhile, HMOs could also directly reduce the occurrence of diseases through the effects of preventing pathogen infection. In this review, we address the probable function of HMOs inside the HMOs-gut microbiota-infant network, by describing the physiological functions of HMOs and the implications of diet on the HMOs-gut microbiota-infant network.

Comparison of Different Labeling Techniques for the LC-MS Profiling of Human Milk Oligosaccharides

Human milk oligosaccharides (HMOs) exhibit various biological activities for infants, such as serving as prebiotics, blocking pathogens, and aiding in brain development. HMOs are a complex mixture of hetero-oligosaccharides that are generally highly branched, containing multiple structural isomers and no intrinsic chromophores, presenting a challenge to both their resolution and quantitative detection. While liquid chromatography-mass spectrometry (LC-MS) has become the primary strategy for analysis of various compounds, the very polar and chromophore-free properties of native glycans hinder their separation in LC and ionization in MS. Various labeling approaches have been developed to achieve separation of glycans with higher resolution and greater sensitivity of detection. Here, we compared five commonly used labeling techniques [by 2-aminobenzamide, 2-aminopyridine, 2-aminobenzoic acid (2-AA), 2,6-diaminopyridine, and 1-phenyl-3-methyl-5-pyrazolone] for analyzing HMOs specifically under hydrophilic-interaction chromatography-mass spectrometry (HILIC-MS) conditions. The 2-AA labeling showed the most consistent deprotonated molecular ions, the enhanced sensitivity with the least structural selectivity, and the sequencing-informative tandem MS fragmentation spectra for the widest range of HMOs; therefore, this labeling technique was selected for further optimization under the porous graphitized carbon chromatography-mass spectrometry (PGC-MS) conditions. The combination strategy of 2-AA labeling and PGC-MS techniques provided online decontamination (removal of excess 2-AA, salts, and lactose) and resolute detection of many HMOs, enabling us to characterize the profiles of complicated HMO mixtures comprehensively in a simple protocol.

Human Milk Oligosaccharide 2'-Fucosyllactose Induces Neuroprotection from Intracerebral Hemorrhage Stroke

Intracerebral hemorrhage (ICH) occurs when brain blood vessels rupture, causing inflammation and cell death. 2-Fucosyllactose (2FL), a human milk oligosaccharide, has potent antiapoptotic and anti-inflammatory effects. The purpose of this study was to examine the protective effect of 2FL in cellular and rodent models of ICH. Hemin was added to a primary rat cortical neuronal and BV2 microglia coculture to simulate ICH in vitro. IBA1 and MAP2 immunoreactivities were used to determine inflammation and neuronal survival. Hemin significantly increased IBA1, while it reduced MAP2 immunoreactivity. 2FL significantly antagonized both responses. The protective effect of 2FL was next examined in a rat ICH model. Intracerebral administration of type VII collagenase reduced open-field locomotor activity. Early post-treatment with 2FL significantly improved locomotor activity. Brain tissues were collected for immunohistochemistry and qRT-PCR analysis. 2FL reduced IBA1 and CD4 immunoreactivity in the lesioned striatum. 2FL downregulated the expression of ER stress markers (PERK and CHOP), while it upregulated M2 macrophage markers (CD206 and TGFβ) in the lesioned brain. Taken together, our data support that 2FL has a neuroprotective effect against ICH through the inhibition of neuroinflammation and ER stress. 2FL may have clinical implications for the treatment of ICH.

The Mean of Milk: A Review of Human Milk Oligosaccharide Concentrations throughout Lactation

Human milk oligosaccharides (HMOs) are non-digestible and structurally diverse complex carbohydrates that are highly abundant in human milk. To date, more than 200 different HMO structures have been identified. Their concentrations in human milk vary according to various factors such as lactation period, mother’s genetic secretor status, and length of gestation (term or preterm). The objective of this review is to assess and rank HMO concentrations from healthy mothers throughout lactation at a global level. To this aim, published data from pooled (secretor and non-secretor) human milk samples were used. When samples were reported as secretor or non-secretor, means were converted to a pooled level, using the reported mean of approximately 80/20% secretor/non-secretor frequency in the global population. This approach provides an estimate of HMO concentrations in the milk of an average, healthy mother independent of secretor status. Mean concentrations of HMOs were extracted and categorized by pre-defined lactation periods of colostrum (0–5 days), transitional milk (6–14 days), mature milk (15–90 days), and late milk (>90 days). Further categorizations were made by gestational length at birth, mother’s ethnicity, and analytical methodology. Data were excluded if they were from preterm milk, unknown sample size and mothers with any known disease status. A total of 57 peer-reviewed articles reporting individual HMO concentrations published between 1996 and 2020 were included in the review. Pooled HMO means reported from 31 countries were analyzed. In addition to individual HMO concentrations, 12 articles reporting total HMO concentrations were also analyzed as a basis for relative HMO abundance. Total HMOs were found as 17.7 g/L in colostrum, 13.3 g/L in transitional milk, and 11.3 g/L in mature milk. The results show that HMO concentrations differ largely for each individual HMO and vary with lactation stages. For instance, while 2′-FL significantly decreased from colostrum (3.18 g/L ± 0.9) to late milk (1.64 g/L ± 0.67), 3-FL showed a significant increase from colostrum (0.37 g/L ± 0.1) to late milk (0.92 g/L ± 0.5). Although pooled human milk contains a diverse HMO profile with more than 200 structures identified, the top 10 individual HMOs make up over 70% of total HMO concentration. In mature pooled human milk, the top 15 HMOs in decreasing order of magnitude are 2′-FL, LNDFH-I (DFLNT), LNFP-I, LNFP-II, LNT, 3-FL, 6′-SL, DSLNT, LNnT, DFL (LDFT), FDS-LNH, LNFP-III, 3′-SL, LST c, and TF-LNH.

Dietary nutrition for neurological disease therapy: Current status and future directions

Adequate food intake and relative abundance of dietary nutrients have undisputed effects on the brain function. There is now substantial evidence that dietary nutrition aids in the prevention and remediation of neurologic symptoms in diverse pathological conditions. The newly described influences of dietary factors on the alterations of mitochondrial dysfunction, epigenetic modification and neuroinflammation are important mechanisms that are responsible for the action of nutrients on the brain health. In this review, we discuss the state of evidence supporting that distinct dietary interventions including dietary supplement and dietary restriction have the ability to tackle neurological disorders using Alzheimer's disease, Parkinson's disease, stroke, epilepsy, traumatic brain injury, amyotrophic lateral sclerosis, Huntington's disease and multiple sclerosis as examples. Additionally, it is also highlighting that diverse potential mechanisms such as metabolic control, epigenetic modification, neuroinflammation and gut-brain axis are of utmost importance for nutrient supply to the risk of neurologic condition and therapeutic response. Finally, we also highlight the novel concept that dietary nutrient intervention reshapes metabolism-epigenetics-immunity cycle to remediate brain dysfunction. Targeting metabolism-epigenetics-immunity network will delineate a new blueprint for combating neurological weaknesses.

In Love with Shaping You-Influential Factors on the Breast Milk Content of Human Milk Oligosaccharides and Their Decisive Roles for Neonatal Development

Human milk oligosaccharides (HMOs) are structurally versatile sugar molecules constituting the third major group of soluble components in human breast milk. Based on the disaccharide lactose, the mammary glands of future and lactating mothers produce a few hundreds of different HMOs implicating that their overall anabolism utilizes rather high amounts of energy. At first sight, it therefore seems contradictory that these sugars are indigestible for infants raising the question of why such an energy-intensive molecular class evolved. However, in-depth analysis of their molecular modes of action reveals that Mother Nature created HMOs for neonatal development, protection and promotion of health. This is not solely facilitated by HMOs in their indigestible form but also by catabolites that are generated by microbial metabolism in the neonatal gut additionally qualifying HMOs as natural prebiotics. This narrative review elucidates factors influencing the HMO composition as well as physiological roles of HMOs on their way through the infant body and within the gut, where a major portion of HMOs faces microbial catabolism. Concurrently, this work summarizes in vitro, preclinical and observational as well as interventional clinical studies that analyzed potential health effects that have been demonstrated by or were related to either human milk-derived or synthetic HMOs or HMO fractions.