Background Breast milk is considered the optimal source of nutrition for infants, providing comprehensive immune protection. Research indicates that breastfed infants exhibit significantly lower rates of viral infection. Human milk oligosaccharides (HMOs), the primary bioactive nutrients in breast milk, not only support gut and brain development but also directly modulate immune responses as prebiotics, anti-adhesives, and antimicrobial agents. This study investigated the effects of adding the HMO 2′-FL to infant formula on the immune function of healthy term infants. Study Design and Methods This study enrolled 424 healthy full-term infants. From day 5 postnatal until 4 months of age, infants were assigned to three groups: a control group (fed formula containing galacto-oligosaccharides GOS), an experimental group (fed formula containing GOS and varying doses of 2′-FL), and a breastfed group. Blood samples were collected at 6 weeks of age to analyse cytokine levels. At study completion, infant urine, faeces, blood, and maternal breast milk samples were obtained. Analyses included plasma, urine, and breast milk 2′-FL concentrations; faecal immunoglobulins; microbiota composition; and gastrointestinal health biomarkers. This paper focuses on blood sample analyses. Key Findings 1. 2'-FL regulates pro-inflammatory cytokine levels and enhances immune function Analysis of pro-inflammatory cytokine levels revealed that infants fed with 2'-FL-fortified formula exhibited cytokine profiles and concentrations more closely aligned with the breastfed group, showing significant divergence from the control group. Moderate pro-inflammatory factors bolster immune function, whereas excessive pro-inflammatory cytokines constitute the fundamental cause of compromised skin barrier integrity and elevated incidence of cutaneous inflammation. Figure 1: Plasma cell inflammatory cytokine concentrations in 6-week-old infants 2. 2'-FL modulates innate immune responses through antigen presentation Pro-inflammatory cytokines are secreted by antigen-presenting cells. These cells are capable of phagocytosing, processing, and presenting antigens to T cells, thereby stimulating T cell activation and proliferation. Experimental results indicate that infants in the 2′-FL group exhibited higher proportions of both CD4+ and CD8+ T cells in their blood compared to the control group. CD4+ cells stimulate the activation of other immune cells, enhancing the immune response, whilst CD8+ cells directly govern cellular immune mechanisms, eliminating infected or abnormal cells. Figure 2: Proportion of T cells in peripheral blood of 6-week-old infants 3. 2'-FL promotes apoptosis and modulates immune responses Apoptosis plays a crucial role in immune regulation. On the one hand, apoptotic cells stimulate macrophages to phagocytose and clear dead cells, thereby enhancing their ability to eliminate pathogens. On the other hand, apoptosis also suppresses the secretion of pro-inflammatory cytokines (such as TNF-α), thereby mitigating inflammatory responses and tissue damage. Experimental results indicate that 2'-FL significantly increased the proportion of apoptotic activated CD8+ T cells, bringing their levels closer to those observed in the breastfed group. Notably, within CD8+ T cells and their subsets, the proportion of the CD8HiCD4Lo subset was significantly higher in the 2'-FL group compared to the control group. Figure 3: Apoptosis in blood samples from 6-week-old infants after 48 hours Discussion and Outlook This study confirms that supplementing infant formula with a single HMO (2′-FL) effectively enhances infants' immune function. By modulating innate and adaptive immune responses, 2′-FL not only improves the immune cytokine profile, bringing it closer to that of the breastfed group, but also regulates immune responses by promoting immune cell apoptosis. These findings indicate that 2′-FL holds significant potential for strengthening and supporting infant immune regulation. The research provides scientific rationale for applying 2′-FL in infant immune health, while opening new avenues for developing HMO-based immune-enhancing functional foods. Future applications of 2′-FL hold promising prospects in preventing and ameliorating human immune-related diseases. Reference [1] Goehring K C, Marriage B J, Oliver J S, et al. Similar to those who are breastfed, infants fed a formula containing 2′-fucosyllactose have lower inflammatory cytokines in a randomized controlled trial[J]. The Journal of nutrition, 2016, 146(12): 2559-2566.

Background Food allergy is a common condition caused by an excessive immune system response, potentially leading to gastrointestinal disorders and systemic allergic reactions. Research indicates that cow's milk allergy (CMA) ranks among the most prevalent food allergies in infants and young children, primarily triggered by allergens such as β-lactoglobulin (β-LG) in milk proteins. Exposure to β-LG induces inflammation and mast cell degranulation (excessive chemical release causing allergic reactions). Human milk oligosaccharides (HMOs), particularly 2′-fucosyllactose (2′-FL), have been demonstrated to strengthen the intestinal barrier and counteract allergic responses by regulating gut microbiota and immune factors. This study investigates the regulatory pathways and potential mechanisms of 2′-FL in modulating food allergic reactions. Study Design and Methods A β-lactoglobulin (β-LG)-induced mouse food allergy model was employed, with mice dividedcontrol, allergic, HMO control, and 2′-FL treatment groups at varying doses. The alleviation effect of 2′-FL on food allergy was assessed by measuring pro-inflammatory cytokine levels and observing mast cell degranulation. Additionally, cellular experiments investigated 2′-FL's effects on the TLR4/NF-κB signalling pathway. This pathway is a key regulator of inflammation; its abnormal activation can trigger robust immune responses. To further elucidate the mechanism of action, the study also analysed the pivotal role of miR-146a (an RNA molecule regulating inflammation) in this process. Key Findings Oral administration of 2′-FL effectively suppressed pro-inflammatory cytokine production and ameliorated β-LG-induced food allergy reactions. In vitro results further confirmed that the mechanism involves 2′-FL regulating miR-146a expression to inhibit the TLR4/NF-κB signalling pathway, thereby reducing inflammatory cytokine expression and mitigating inflammatory responses, effectively alleviating food allergy symptoms. 2′-FL significantly alleviates inflammation induced by food allergy Compared with the allergy group, supplementation with 2′-FL markedly reduced mast cell infiltration and inflammatory symptoms associated with allergic reactions. The most pronounced alleviation was observed in the high-dose group. Figure 1: 2′-FL alleviates inflammatory symptoms in β-LG-induced allergic mice 2′-FL effectively alleviates allergic inflammatory responses by reducing concentrations of inflammatory cytokines. Intervention with 2′-FL significantly decreased serum concentrations of the inflammatory cytokines TNF-α, IL-4, and IL-6, alongside their mRNA expression within colonic tissue, with the most pronounced effects observed in the high-dose group. This demonstrates that 2′-FL can effectively mitigate allergic inflammatory responses. Figure 2: 2′-FL reduces the expression of inflammatory cytokines By modulating the activity of inflammatory signalling pathways, 2′-FL inhibits the expression of genes associated with allergic inflammation. In cellular experiments, 2′-FL reduced the expression levels of inflammation-related genes and proteins by suppressing the activity of TLR4 and NF-κB. TLR4 and NF-κB serve as pivotal switches for immune cells to detect danger signals, and their excessive activation amplifies immune responses. Figure 3: Effect of 2′-FL on the TLR4/NF-κB signalling pathway in β-LG-induced cells 2′-FL activates the expression of inflammation-associated RNA molecules, thereby reducing the activity of inflammatory signalling pathways. Research has further revealed that miR-146a serves as a key regulator in the inhibition of the TLR4/NF-κB signalling pathway by 2′-FL. Overexpression of miR-146a enhances the anti-inflammatory effects of 2′-FL, whereas its suppression attenuates this action, indicating its pivotal role in immune regulation. Figure 4: Effect of 2′-FL on miR-146a expression in cells Discussion and Outlook This study confirms that 2′-FL effectively alleviates β-lactoglobulin-induced allergic reactions by regulating the miR-146a-mediated TLR4/NF-κB inflammatory signalling pathway. 2′-FL not only reduces allergy-related inflammatory mediators but also significantly diminishes the occurrence of allergic symptoms by modulating immune system balance. This research provides scientific rationale for the application of 2′-FL in anti-allergy interventions and offers new directions for developing HMO-based functional foods with anti-allergic properties. Future studies suggest 2′-FL holds promising prospects for broader applications in the prevention and treatment of human allergic diseases. Reference [1] Li A, Li Y, Zhang X, et al. The human milk oligosaccharide 2′-fucosyllactose attenuates β-lactoglobulin–induced food allergy through the miR-146a–mediated toll-like receptor 4/nuclear factor-κB signaling pathway[J]. Journal of dairy science, 2021, 104(10): 10473-10484.

Background Inflammatory bowel disease (IBD) is a chronic condition characterised by persistent intestinal inflammation, with colitis being one of its most prevalent manifestations. Research indicates that IBD development is frequently associated with gut microbiota dysbiosis and immune system hyperreactivity. 2′-Fucosyllactose (2′-FL), a key component of human milk oligosaccharides (HMOs), contributes to establishing a healthy gut microbiota and modulating immune responses. This study aims to evaluate the efficacy of 2′-FL in alleviating colitis and explore its potential for improving IBD-related symptoms. Study Design and Methods A DSS (d-starch sulphate) induced colitis mouse model was employed, with mice dividedcontrol, low-dose 2′-FL, high-dose 2′-FL, and other groups. The efficacy of 2′-FL in alleviating IBD-related symptoms was evaluated by recording indicators such as body weight and disease activity index (DAI). Furthermore, 16S rDNA sequencing was employed to analyse changes in the gut microbiota, and alterations in serum inflammatory marker levels were detected to gain further insightthe anti-inflammatory mechanisms of 2′-FL. Key Findings 1. 2′-FL alleviates colitis disease symptoms Compared to the control group with DSS-induced colitis, mice treated with 2′-FL exhibited a lower proportion of weight loss attributable to disease and significantly reduced disease activity index (DAI) scores. This indicates that 2′-FL effectively mitigates intestinal inflammatory symptoms, with the most pronounced effect observed in the high-dose group. Figure 1: Effect of 2′-FL on colitis symptoms in a mouse model of 3% DSS-induced colitis 2. 2′-FL improves gut microbiota balance and metabolism 16S rDNA sequencing revealed that 2′-FL significantly restored the balance of gut microbiota disrupted by DSS-induced dysbiosis, increasing the proportion of beneficial bacteria such as Lactobacillus. Furthermore, 2′-FL promoted the production of beneficial bacterial metabolites known as short-chain fatty acids (SCFAs). These metabolites not only aid in maintaining intestinal barrier function but also exert anti-inflammatory effects. Figure 2: Comparison of gut microbial communities across different groups Figure 3: Heatmap of Spearman correlations between gut microbiota and SCFAs 3. 2′-FL Modulates Inflammatory Cytokine Levels Serum analysis revealed that 2′-FL effectively reduced levels of the pro-inflammatory cytokines TNF-α and IL-6 in colitis-affected mice, while simultaneously increasing expression of the anti-inflammatory cytokine IL-10, thereby diminishing the inflammatory response. Figure 4: Effect of 2′-FL on Serum Levels of Inflammatory Markers Discussion and Outlook This study has demonstrated the beneficial effects of 2′-FL in alleviating inflammatory bowel disease (IBD). 2′-FL not only supports gut health by improving the gut microbiota and promoting the production of beneficial metabolites, but also significantly reduces intestinal inflammation by regulating immune responses through balancing pro-inflammatory and anti-inflammatory factors. Future research may further explore the clinical application potential of 2′-FL in IBD patients and investigate its role in other intestinal disorders and immune health management, particularly its potential in promoting gut health and immunomodulation. Reference [1] Li A, Ni W, Li Y, et al. Effect of 2′-fucosyllactose supplementation on intestinal flora in mice with intestinal inflammatory diseases[J]. International Dairy Journal, 2020, 110: 104797.  

Background Skin inflammations such as psoriasis are caused by excessive proliferation of skin cells and persistent inflammatory responses triggered by immune system dysregulation. Research indicates that 2′-fucosyllactose (2′-FL), a key oligosaccharide in human milk, alleviates symptoms of skin inflammations like psoriasis by modulating relevant immune responses. This study explores the potential mechanisms by which 2′-FL inhibits psoriasis-like skin inflammation, offering novel insights for alleviating such conditions. Study Design and Methods A psoriasis mouse model induced by imiquimod (IMQ) was employed. Six-week-old female mice were dividedgroups receiving dietary interventions with varying concentrations of 2′-FL (0.25%–5%). Skin inflammation severity was assessed using the Psoriasis Area and Severity Index (PAS). To elucidate the specific regulatory mechanisms of 2′-FL on psoriasiform skin inflammation, the study analysed the proportion of Th17 cells—inflammatory cells associated with psoriasis—via flow cytometry and Western blot techniques. It further examined alterations in STAT3, a key signalling pathway regulating Th17 cells, and the expression of RORyt, a crucial transcription factor influencing Th17 cell differentiation. Key Findings Th17 cells and their associated pro-inflammatory cytokines exert a pivotal influence in the pathogenesis of psoriasis. 2′-FL significantly suppressed cutaneous inflammation by modulating STAT3—a key signalling pathway in immune response and inflammatory regulation—and RORyt, a crucial transcription factor governing Th17 cell differentiation. 2′-FL markedly ameliorates psoriasiform skin inflammation Mice treated with 2′-FL exhibited significantly improved skin inflammation, with marked reductions in erythema, scaling, and skin thickness, alongside a significant decrease in PAS scores. This demonstrates 2′-FL's efficacy in alleviating cutaneous inflammatory responses. Figure 1: Mice treated with 2′-FL exhibit a reduced inflammatory response to IMQ 2′-FL effectively reduced skin inflammation by decreasing the expression of Th17 cells and their associated pro-inflammatory factors. Further analysis revealed that the proportion of Th17 cells in mice treated with 2′-FL was significantly reduced, with a corresponding decrease in the expression of related pro-inflammatory factors such as IL-17 and IL-22, thereby effectively mitigating the skin inflammatory response. Figure 2: 2′-FL reduced the mRNA expression of Th17-associated cytokines in skin lesions of IMQ-treated mice. 2′-FL reduces the expression of Th17 cells and their associated pro-inflammatory cytokines by modulating the STAT3 signalling pathway and the cellular transcription factor RORyt. Further research has elucidated the specific mechanism by which 2′-FL inhibits Th17 cells. By suppressing the phosphorylation of the STAT3 signalling pathway and the expression of the cellular transcription factor RORyt, 2′-FL effectively prevents the excessive differentiation and activation of Th17 cells, thereby inhibiting inflammatory responses. Figure 3: 2′-FL reduced STAT3 phosphorylation and the relative mRNA expression levels of RORγt in skin lesions of IMQ-treated mice. Discussion and Outlook This study demonstrates that 2′-FL exerts a significant inhibitory effect on cutaneous inflammation. By modulating STAT3—a key signalling pathway in immune responses and inflammatory regulation—and RORγt—a crucial transcription factor in Th17 cell differentiation—2′-FL reduces the expression of inflammatory Th17 cells and their associated pro-inflammatory mediators. This effectively suppresses the progression of psoriatic symptoms, offering novel therapeutic insights for psoriasis and other inflammatory skin conditions. Future research may further explore the application potential of 2′-FL in human immune-mediated skin disorders, particularly its role in the long-term management of chronic inflammatory and autoimmune conditions. Reference [1] Lei K, Wang D, Lin L, et al. 2′-fucosyllactose inhibits imiquimod-induced psoriasis in mice by regulating Th17 cell response via the STAT3 signaling pathway[J]. International Immunopharmacology, 2020, 85: 106659.

Background Vaccination is pivotal in enhancing human resistance to infectious diseases. However, infants, young children, and other immunocompromised individuals often struggle to generate sufficient antibodies post-vaccination, thereby compromising the vaccine's intended protective efficacy. 2′-Fucosyllactose (2′-FL), a key oligosaccharide in human milk, possesses immune-enhancing properties and can bolster vaccine protection by stimulating the immune system. Study Design and Methods This study employed an influenza vaccination model. Six-week-old female mice were dividedgroups and administered dietary interventions with varying concentrations of 2′-FL (0.25%–5%) prior to vaccination. To evaluate 2′-FL's impact on immune function, assessments were conducted on delayed-type hypersensitivity (DTH), serum immunoglobulin (IgG1 and IgG2a) levels, B-cell activation, and T-cell proliferation. DTH represents a reaction occurring within days of vaccination, reflecting the body's defensive capacity against specific antigens. Higher serum immunoglobulin levels (IgG1 and IgG2a) typically indicate stronger humoral immunity. B-cell activation and T-cell proliferation, meanwhile, reflect the immune system's active response to the vaccine. Key Findings 1. 2′-FL Enhances DTH Immune Response Dietary 2′-FL significantly amplified the DTH response in mice, indicating markedly enhanced immune defence against specific antigens. The intensity of the DTH response correspondingly increased with rising 2′-FL concentrations, demonstrating that 2′-FL effectively promotes the immune system's defensive capabilities. Figure 1: Effects of 2′-FL dietary intervention on vaccine-specific delayed-type hypersensitivity (DTH) 2. 2′-FL elevates immunoglobulin levels Research indicates that serum levels of immunoglobulins IgG1 and IgG2a were significantly elevated in mice treated with 2′-FL. These immunoglobulins constitute vaccine-induced specific antibodies, and their increase signifies enhanced humoral immunity. Figure 2: Effect of 2′-FL dietary intervention on antibody levels in serum collected on day 31 3. 2′-FL promotes B-cell activation Flow cytometry analysis revealed significantly heightened levels of B-cell activation in the spleen and mesenteric lymph nodes of mice administered 2′-FL. This indicates enhanced antibody production capacity, facilitating more effective neutralisation of invading pathogens. Figure 3: Flow cytometric analysis of B-cell subsets in spleen and mesenteric lymph nodes (MLN) collected on day 31 following 2′-FL dietary intervention. 4. 2′-FL Promotes T-Cell Proliferation Research has demonstrated that 2′-FL significantly enhances the proliferation of both CD4+ and CD8+ T cells, thereby strengthening the protective function of vaccine-specific cellular immunity. The increase in CD4+ T cells aids in activating other immune cells, while CD8+ T cells are responsible for directly attacking infected cells. This indicates that 2′-FL plays a positive role in enhancing overall immune function. Figure 4: Percentage of CD4+ and CD8+ T cells proliferating following re-stimulation in vitro of bone marrow dendritic cells (BMDCs) loaded with influenza virus Discussion and Outlook This study demonstrates that 2′-FL exhibits significant efficacy in enhancing vaccine immunogenicity. This is manifested through enhanced DTH responses, markedly elevated serum immunoglobulin levels (IgG1 and IgG2a), increased B-cell activity, and T-cell proliferation. These findings indicate that 2′-FL effectively boosts both humoral and cellular immunity, providing a theoretical foundation for its potential application as an immunostimulant in infant formula. Future research may further explore the potential application of 2′-FL in human vaccination programmes and evaluate its long-term benefits in neonatal immune development, particularly its role in promoting immunological health. Reference [1] Xiao L, Leusink-Muis T, Kettelarij N, et al. Human milk oligosaccharide 2′-fucosyllactose improves innate and adaptive immunity in an influenza-specific murine vaccination model[J]. Frontiers in immunology, 2018, 9: 452.

Background Allergic reactions have exhibited a marked global increase in recent years, particularly among infants and young children, leading to serious health concerns. Existing treatments primarily focus on allergen avoidance and managing acute allergic reactions, with a lack of effective long-term relief strategies. Human milk oligosaccharides (HMOs), as natural constituents of breast milk, not only function as prebiotics but also demonstrate direct immunomodulatory capabilities. Among these, 2′-fucosyllactose (2′-FL) stands as one of the most crucial components, offering renewed hope in this field through its potential application in alleviating allergic symptoms. This paper will focus on the immunomodulatory effects of 2′-FL in allergic reactions and its potential clinical applications. Research Design and Methods This study employed an ovalbumin (OVA)-sensitised mouse model to evaluate the efficacy of 2′-FL in alleviating allergic symptoms. Mice were treated with oral 2′-FL and subjected to OVA challenge to induce allergic reactions. The study primarily observed the effects of 2′-FL on allergic symptoms such as diarrhoea and body temperature changes, while simultaneously measuring serum levels of mast cell proteinase-1 (mMCP-1). mMCP-1 serves as a marker for mast cell activation, with elevated levels indicating more severe allergic reactions. Furthermore, the study investigated 2′-FL's effects on regulatory T cells (Tregs), which control immune responses by suppressing excessive immune reactions and preventing inflammation and allergic reactions. Key Findings 1. 2′-FL significantly alleviates allergic symptoms Experimental results indicate that 2′-FL treatment markedly reduced diarrhoea symptoms in allergic mice and effectively suppressed hypothermia. Compared to untreated mice, those administered oral 2′-FL exhibited significantly diminished allergic responses, demonstrating the compound's pronounced efficacy in alleviating allergic symptoms. Figure 1: Effects of daily oral administration of 2′-FL on diarrhoea severity (A) and rectal temperature (B) following repeated ovalbumin (OVA) challenge. 2. 2′-FL Inhibits Mast Cell Activation Research further indicates that 2′-FL significantly reduces serum levels of mast cell protease-1 (mMCP-1). Mast cells serve as pivotal effector cells in allergic reactions; by inhibiting mast cell degranulation, 2′-FL diminishes the release of allergic mediators, thereby alleviating allergic symptoms. Figure 2: Effect of daily oral administration of 2′-FL on serum mast cell protease-1 (mMCP-1) levels following repeated ovalbumin (OVA) challenge 3. 2′-FL increases the proportion of regulatory T cells The findings further indicate that 2′-FL treatment significantly increased the proportion of regulatory T cells within the Peyer's patches of mice, particularly those secreting the anti-inflammatory cytokine IL-10. These T cells are capable of suppressing allergic reactions by secreting anti-inflammatory factors, further elucidating the immunomodulatory effects of 2′-FL. Figure 3: Effect of daily oral administration of 2′-FL on IL-10 cell populations in Peyer's patches Discussion and Outlook This study demonstrates that 2′-FL plays a significant role in alleviating allergic reactions, not only reducing acute allergic symptoms but also preventing their onset by modulating the immune system, inhibiting mast cell activation, and increasing the proportion of regulatory T cells. Future investigations may explore its potential in early intervention strategies, such as incorporating 2′-FLinfant formula to foster a more robust immune system and reduce allergy incidence. As research progresses, 2′-FL holds promise as a pivotal component in allergy prevention and treatment, offering expanded possibilities for managing allergies in infants, young children, and adults alike. Reference [1] Castillo‐Courtade L, Han S, Lee S, et al. Attenuation of food allergy symptoms following treatment with human milk oligosaccharides in a mouse model[J]. Allergy, 2015, 70(9): 1091-1102.