Human milk oligosaccharide secretion dynamics during breastfeeding and its antimicrobial role: A systematic review

Table 4 Studies of anti-bacterial effects of human milk oligosaccharides

Ref.	Type of article	Microbes investigated	Types of HMOs	Mechanisms of action	Key findings	Patient population
Morrow et al[76]	Observational study	Campylobacter jejuni, Calicivirus	2′-FL, LNDFH	Inhibits pathogen adhesion by mimicking host glycans; Modulates immune responses, reducing intestinal inflammation	Significant reduction in diarrhea incidence (P = 0.004 for Campylobacterjejuni, P = 0.012 for Calicivirus)	Breastfed human infants
Yu et al[77]	Experimental study	Campylobacter jejuni	2′-FL	Prevents bacterial adhesion to epithelial cells; Suppresses pro-inflammatory cytokines (IL-8, IL-1β)	Colonization reduced by 80% in mouse models; Lowered intestinal inflammation	Mouse model
Facinelli et al[78]	Experimental in vitro study	E. coli, Salmonella fyris	2'-FL, 6'-SL	2'-FL and 6'-SL significantly reduced the adhesion of Escherichia coli to Caco-2 cells at human milk concentrations but no effect on Salmonella fyris	Reducing the adhesion of harmful bacteria like E. coli	Bacterial adhesion to Caco-2 cells (a human intestinal cell line) cultures
Wang et al[79]	Experimental study	E. coli O157: H7	2′-FL	Acts as a soluble decoy receptor; Enhances mucin secretion (MUC2); Promotes microbiota balance	Colonization reduced by > 90% in mouse intestines; Lowered pro-inflammatory cytokines (IL-6, TNF-α)	Mouse model
Lin et al[99]	Experimental study	UPEC	Neutral and sialic acid-rich HMOs	Reduces bacterial internalization into epithelial cells. Suppresses UPEC-induced proinflammatory signaling (MAPK, NF-κB)	Reduced cytotoxicity and improved bladder epithelial integrity; Decreased cell death and detachment	In vitro bladder epithelial cells
Martín-Sosa et al[100]	Experimental study	ETEC, UPEC	Sialylated oligosaccharides	HMOs strongly inhibited hemagglutination mediated by ETEC strains expressing CFA/I and CFA/II. HMOs also inhibited hemagglutination by UPEC strains	The inhibitory capacity was significantly reduced when HMOs were desialylated, highlighting the importance of the sialylated fraction	In vitro
Coppa et al[102]	Experimental study	EPEC, Vibrio cholerae, Salmonella fyris	Acidic, neutral high-molecular-weight, and neutral low-molecular-weight HMOs	Blocks bacterial adhesion to Caco-2 cells by acting as decoy receptors	Acidic HMOs inhibit all three pathogens. Neutral high-molecular-weight HMOs inhibit E. coli and V. cholerae. Neutral low-molecular-weight HMOs inhibit E. coli and S. fyris	In vitro with Caco-2 cells
Newburg et al[103]	Experimental study	E. coli (heat-stable enterotoxin, (ST)	Fucosylated HMOs	Oligosaccharide fraction provided significant protection against the diarrheagenic effects of E. coli heat-ST), while the lactose fraction did not	Among HMOs, the neutral fraction exhibited protective activity, whereas the acidic fraction did not (22% vs 57% mortality, respectively	Suckling mouse model
Noguera-Obenza et al[101]	Observational study	EHEC, EPEC	Not specified; focus on secretory IgA (sIgA) in human milk	Neutralizes bacterial adhesion by targeting virulence antigens (e.g., EspA, EspB, intimin)	sIgA in human milk reduces adhesion of EHEC/EPEC to gut epithelium. - Antibodies are regionally variable and linked to pathogen exposure history	Milk samples from breastfeeding mothers (United States and Mexico)
He et al[109]	Experimental study	AIEC	Exosome-encapsulated HMOs (e.g., 2’-FL, Sialyl lactose)	Modulates immunity by reducing LPS-induced inflammation. Promotes anti-inflammatory macrophage phenotype	Reduced intestinal inflammation and bacterial load in AIEC-infected mice	In vivo murine model
Manthey et al[80]	Experimental study	EPEC	Various HMOs	Blocks bacterial attachment by acting as decoy receptors	Reduced EPEC attachment in vitro; Decreased intestinal colonization in mouse models	In vitro epithelial cells and suckling mice models
Chambers et al[81]	Experimental study	GB. streptococcus	Pooled and single-entity HMOs	Increases cell permeability; Bioorthogonal probes retain activity and identify cellular targets	Up to 90% growth inhibition by pooled HMOs; DFL, LNT-II, and LSTa exhibit significant antibacterial activity (35%-60%)	In vitro GB. streptococcus cultures
Chambers et al[117]	Experimental study	GB. streptococcus	Various HMOs	Increases membrane permeability. Perturbs metabolic pathways, including glycerophospholipid and linoleic acid metabolism	Potentiated trimethoprim activity, reducing MIC by up to 512-fold; Synergistic effects observed in combination therapy	In vitro studies with clinical GB. streptococcus isolates
Ackerman et al[82]	Experimental study	GB. streptococcus	Pooled donor HMOs	Disrupts biofilm formation; Alters bacterial cell arrangement	Donor-specific effects: HMOs from some donors inhibited biofilm production and bacterial growth by 40%; Biofilm structure changes were observed using electron microscopy	In vitro GB. streptococcus cultures from human donors
Lin et al[83]	Experimental study	GB. streptococcus	Neutral (non-sialylated) HMOs	Direct bacteriostatic effect; Neutral HMOs inhibit growth by impairing glycosyltransferase functions; Synergistic effects with antibiotics	Neutral HMOs reduce GB. streptococcus growth by up to 98%; Identified glycosyltransferase (gbs0738) as a target for HMO-mediated inhibition; Synergy observed with vancomycin and ciprofloxacin, significantly lowering the required antibiotic dose	In vitro GB. streptococcus cultures
Moore et al[84]	Experimental study	GB. streptococcus	Purified HMOs	Inhibits biofilm formation in colonizing and invasive strains; Exhibits strain-specific effects based on capsular serotype and sequence type	50% biofilm inhibition for colonizing strains, 45% for invasive strains; Significant inhibition across multiple capsular types (CpsIb, CpsII, etc.); Effective biofilm dismantling of mature biofilms	30 diverse clinical and laboratory strains of GB. streptococcus (in vitro analysis)
Andreas et al[118]	Clinical and experimental study	GB. streptococcus	Specific fucosylated HMOs	Reduces GB. streptococcus colonization in mothers and infants; Acts bacteriostatically, impairing glycosyltransferase-dependent cell proliferation	LNDFHI and related HMOs reduce GB. Streptococcus growth by 50%; Lewis-positive mothers produce HMOs that reduce maternal and infant colonization; Lewis-negative mothers could benefit from synthetic HMO supplementation	Gambian mother-infant pairs and in vitro analysis
Mysore et al[85]	Preclinical study	Helicobacter pylori	38-SL, a natural HMO analog	Inhibits bacterial adhesion to gastric epithelial cells; Acts as a decoy receptor preventing colonization	2 out of 6 animals achieved permanent H. pylori eradication; Safe and showed efficacy in rhesus monkey model; Transient decrease in bacterial load observed in other regimens	H. pylori-positive rhesus monkeys
Parente et al[86]	Double-blind, placebo-controlled clinical trial	Helicobacter pylori	3’SL	3’SL fail to eradicate or suppress H. pylori infection		Adults with dyspepsia and confirmed H. pylori infection
Jantscher-Krenn et al[116]	Experimental study	Entamoeba histolytica	Pooled HMOs	Reduces trophozoite attachment to intestinal epithelium	LNT has significant protection (up to 80%) while fucosylated HMOs are ineffective. GOS completely block E. histolytica attachment and cytotoxicity at 8 mg/mL	In vitro cultures of E. histolytica and human intestinal epithelial HT-29 cells
Nguyen et al[105]	Experimental study	Clostridium difficile, specifically focusing on its toxin A (TcdA) and the carbohydrate binding site (TcdA-f2)	LNFPV & LNH	A mixture of HMOs binds to the carbohydrate binding site of Clostridium difficile toxin A (TcdA-f2) at a concentration of 20 g/mL	LNFPV and LNH demonstrated strong binding with TcdA-f2, exhibiting docking energies of -9.48 kcal/mol and -12.81 kcal/mol, respectively

2'-FL: 2'-Fucosyllactose; 3-FL: 3-Fucosyllactose; 3'-SL: 3'-Sialyllactose; 6'-SL: 6'-Sialyllactose; 38-SL: 38-sialyllactose; AIEC: Adherent-Invasive E. coli; CFAs: Colonization factor antigens; CD4: Cluster of differentiation 4+; CD8: cluster of differentiation 8+; DFL: Difucosyllactose; Escherichia coli: E. coli, EHEC: Enterohemorrhagic E. coli; EPEC: Enteropathogenic E. coli; ETEC: Enterotoxigenic Escherichia coli; GB. streptococcus: Group B streptococci; HBGAs: Histo-blood group antigens; HIEs: Human intestinal enteroids; HMOs: Human milk oligosaccharides; IgA: Immunoglobulin A; IL-1β: Interleukin-1 beta; IL-6: Interleukin-6; IL-8: Interleukin-8; LNFPV: Lacto-N-fucopentaose; LNDFH: Lacto-N-Difucohexaose; LNDFHI: lacto-N-difucohexaose I; LNH: Lacto-N-neohexaose; LNT: Lacto-N-Tetraose; LNT-II: lacto-N-triose II; LPS: Lipopolysaccharides; LSTa: LS-tetrasaccharide a; MIC: Minimum inhibitory concentration; NF-κB: Nuclear factor kappa B; PBMCs: Peripheral blood mononuclear cells; RSV: Respiratory syncytial virus; RV: Rota virus; SA: Sialic acid; TcdA-f2: Clostridium difficile toxin A; Th1: T helper 1; Th2: T helper 2; TNF-α: Tumor necrosis factor; UPEC: Uropathogenic E. coli.