Innate Immune Recognition, Integrated Stress Response, Infection, and Tumorigenesis.

Engagement of PRRs in recognition of PAMPs or DAMPs is one of the processes that initiates cellular stress. These sensors are involved in signaling pathways leading to induction of innate immune processes. Signaling initiated by PRRs is associated with the activation of MyD88-dependent signaling pathways and myddosome formation. MyD88 downstream signaling depends upon the context of signaling initiation, the cell (sub)type and the microenvironment of signal initiation. Recognition of PAMPs or DAMPs through PRRs activates the cellular autonomous defence mechanism, which orchestrates the cell responses to resolve specific insults at the single cell level. In general, stressed endoplasmic reticulum is directly linked with the induction of autophagy and initiation of mitochondrial stress. These processes are regulated by the release of Ca2+ from ER stores accepted by mitochondria, which respond through membrane depolarization and the production of reactive oxygen species generating signals leading to inflammasome activation. In parallel, signaling from PRRs initiates the accumulation of misfolded or inappropriately post-translationally modified proteins in the ER and triggers a group of conserved emergency rescue pathways known as unfolded protein response. The cell-autonomous effector mechanisms have evolutionarily ancient roots and were gradually specialized for the defence of specific cell (sub)types. All of these processes are common to the innate immune recognition of microbial pathogens and tumorigenesis as well. PRRs are active in both cases. Downstream are activated signaling pathways initiated by myddosomes, translated by the cellular autonomous defence mechanism, and finalized by inflammasomes.

Lectin microarray profiling demonstrates equivalent global glycosylation for whey protein ingredients enriched with α-lactalbumin and milk fat globule membrane.

Human milk fat globule membrane (MFGM) and whey proteins are nutritionally and functionally valuable, with many beneficial bioactivities associated with their glycosylation. However glycosylation of milk components other than free milk oligosaccharides are underinvestigated. Whey protein concentrate (WPC) ingredients with various enrichments or depletions are used in infant formula (IF) formulations to contribute to human milk equivalence and bioactivity benefits, but their overall or global glycosylation has not been compared. We compared the global glycosylation of commercial WPC ingredients for use in various IF formulations; two MFGM-enriched WPC ingredients (high fat HF1 and lower fat HF2), an α-lactalbumin-enriched WPC (WPC Lac) which has α-lactalbumin concentration closer to human milk and significantly less ß-lactoglobulin which is not present in human milk, and two base WPC ingredients (WPC 80 and WPC 35) using lectin microarray profiling. WPC Lac and WPC HF1 glycosylation were highly similar to each other and both somewhat similar to WPC 35, while WPC HF2 was more similar to the base WPC 80 ingredient. N-linked glycosylation analysis demonstrated that WPC HF1 and WPC Lac were qualitatively most similar to one another, with WPC 80 and WPC 35 having similar structures, confirming lectin microarray profiling as a valuable method to compare global glycosylation. Thus WPC Lac may be a valuable ingredient for providing equivalent glycosylation to MFGM supplementation.

Transcriptomic Analysis of Glycosylation and Neuroregulatory Pathways in Rodent Models in Response to Psychedelic Molecules.

The potential for psychedelic molecules in impacting cognitive flexibility has long been supported and acknowledged across scientific reports. In the current study, an approach leveraging knowledge-based gene-set information analysis has been adopted to explore the potential impact of psychedelic molecules on both glycosylation, (a post-translational modifications (PTM)) and on neuro-regulatory pathways. Though limitations and restrictions rise from the scarcity of publicly available 'omics' data, targeted analysis enabled us to identify a number of key glycogenes (Hexb, Hs6st2, Col9a2, B3gat2, Mgat5, Bgn) involved the structural organization of extracellular matrix and neuroprotective factors (Kl, Pomc, Oxt, Gal, Avp, Cartpt) which play vital roles in neuron protection, development as well as synaptic stability. In response to psychedelic molecules, we found that these genes and associated pathways are transcriptional altered in rodent models. The approach used indicates the potential to exploit existing datasets for hypothesis generation and testing for the molecular processes which play a role in the physiological response to psychedelic molecule effects. These reported findings, which focused on alterations in glycogenes and neuro-regulatory factors may provide a novel range of biomarkers to track the beneficial, as well as potential toxicological effects of psychedelic molecules.

Systematic review of topical interventions for the management of odour in patients with chronic or malignant fungating wounds.

Chronic wounds adversely affect the quality of life of individuals and odour is a well-recognised associated factor. Odour can affect sleep, well-being, social interactions, diet and potentially wound healing. This systematic review aims to examine the effectiveness of topical interventions in the management of odour associated with chronic and malignant fungating wounds. A systematic review guided by PRISMA recommendations of randomised controlled trials where odour intensity/odour is the primary outcome was undertaken. Inclusion criteria were adults (18 years and over) with chronic venous, arterial, diabetic or pressure ulcers or with malignant fungating wounds where odour has been managed through topical application of pharmacological/non-pharmacological agents. Searches were conducted in CENTRAL, CINAHL, EMBASE, MEDLINE, Scopus, and Web of Science. Eligibility screening, risk of bias assessment and data extraction was completed by authors working independently. Searches retrieved 171 titles and abstracts (157 post de-duplication). Thirteen studies were retained for full text review of which five (n = 137 individuals) examining the following treatments remained: metronidazole (n = 4), silver (n = 1). Meta-analysis was not possible but individual studies suggest improved outcomes (i.e., reduced odour) using metronidazole. Treatment options to manage wound odour are limited and hampered by lack of clinical trials, small sample sizes, and absence of standardised outcomes and consistent measurement. Whereas metronidazole and silver may have a role in controlling wound odour, robust and well-designed interventions with rigorous procedures and standardised odour outcomes are necessary to evaluate their contribution.

Maximum depth sequencing reveals an ON/OFF replication slippage switch and apparent in vivo selection for bifidobacterial pilus expression.

The human gut microbiome, of which the genus Bifidobacterium is a prevalent and abundant member, is thought to sustain and enhance human health. Several surface-exposed structures, including so-called sortase-dependent pili, represent important bifidobacterial gut colonization factors. Here we show that expression of two sortase-dependent pilus clusters of the prototype Bifidobacterium breve UCC2003 depends on replication slippage at an intragenic G-tract, equivalents of which are present in various members of the Bifidobacterium genus. The nature and extent of this slippage is modulated by the host environment. Involvement of such sortase-dependent pilus clusters in microbe-host interactions, including bacterial attachment to the gut epithelial cells, has been shown previously and is corroborated here for one case. Using a Maximum Depth Sequencing strategy aimed at excluding PCR and sequencing errors introduced by DNA polymerase reagents, specific G-tract sequences in B. breve UCC2003 reveal a range of G-tract lengths whose plasticity within the population is functionally utilized. Interestingly, replication slippage is shown to be modulated under in vivo conditions in a murine model. This in vivo modulation causes an enrichment of a G-tract length which appears to allow biosynthesis of these sortase-dependent pili. This work provides the first example of productive replication slippage influenced by in vivo conditions. It highlights the potential for microdiversity generation in "beneficial" gut commensals.

Gastrointestinal Symptoms in Autism Spectrum Disorder: A Systematic Review.

This systematic review aims to offer an updated understanding of the relationship between gastrointestinal symptoms (GIS) and autism spectrum disorder (ASD) in children and adolescents. The databases PsycINFO, Medline, Cinahl, and ERIC were searched using keywords, and relevant literature was hand-searched. Papers (n = 3319) were systematically screened and deemed eligible if they were empirical studies published in English since 2014 and measured the GIS of individuals with ASD who were under 18 years old. Thirty studies were included in the final review. The study findings were synthesized under eight themes, including the prevalence and nature of GIS and their relationship with developmental regression, language and communication, ASD severity, challenging behavior, comorbid psychopathology, sleep problems, and sensory issues. The review found that GIS were common and that there was contradictory evidence concerning their relationship with co-occurring conditions. It also identified evidence of some causal relationships that support the existence of the gut-immune-brain pathways. Future research needs to use large prospective designs and objective and standardized GIS measurements to provide a nuanced understanding of GIS in the context of ASD.

Mucin Purification and Printing Natural Mucin Microarrays.

Mucin glycosylation is the key facilitator of microbial attachment and nutrition and it varies according to biological location, health and disease status, microbiome composition, infection, and multiple other factors. Mucin glycans have also been reported to attenuate pathogen virulence and mediate biofilm dispersal. With the labor intensive and time-consuming purification required for natural mucins and their low quantitative yield from biological sources, natural mucin microarrays provide a convenient and multiplexed platform to study mucin glycosylation and interactions. In this chapter we describe the purification of natural mucins, using sputum as an example biological source, and the printing of natural mucin microarrays.

Ascaris lumbricoides and ticks associated with sensitization to galactose α1,3-galactose and elicitation of the alpha-gal syndrome.

BACKGROUND: IgE to galactose alpha-1,3 galactose (alpha-gal) causes alpha-gal syndrome (delayed anaphylaxis after ingestion of mammalian meat). Development of sensitization has been attributed to tick bites; however, the possible role of other parasites has not been well studied. OBJECTIVE: Our aims were to assess the presence, relative abundances, and site of localization of alpha-gal-containing proteins in common ectoparasites and endoparasites endemic in an area of high prevalence of alpha-gal syndrome, as well as to investigate the ability of ascaris antigens to elicit a reaction in a humanized rat basophil in vitro sensitization model. METHODS: Levels of total IgE, Ascaris-specific IgE, and alpha-gal IgE were measured in sera from patients with challenge-proven alpha-gal syndrome and from controls without allergy. The presence, concentration, and localization of alpha-gal in parasites were assessed by ELISA, Western blotting, and immunohistochemistry. The ability of Ascaris lumbricoides antigen to elicit IgE-dependent reactivity was demonstrated by using the RS-ATL8 basophil reporter system. RESULTS: Alpha-gal IgE level correlated with A lumbricoides-specific IgE level. Alpha-gal protein at 70 to 130 kDa was detected in A lumbricoides at concentrations higher than those found in Rhipicephalus evertsi and Amblyomma hebraeum ticks. Immunohistochemistry was used to localize alpha-gal in tick salivary acini and the helminth gut. Non-alpha-gal-containing A lumbricoides antigens activated RS-ATL8 basophils primed with serum from subjects with alpha-gal syndrome. CONCLUSION: We demonstrated the presence, relative abundances, and site of localization of alpha-gal-containing proteins in parasites. The activation of RS-ATL8 IgE reporter cells primed with serum from subjects with alpha-gal syndrome on exposure to non-alpha-gal-containing A lumbricoides proteins indicates a possible role of exposure to A lumbricoides in alpha-gal sensitization and clinical reactivity.

Correction: Examination of oestrus-dependent alterations of bovine cervico-vaginal mucus glycosylation for potential as optimum fertilisation indicators.

Correction for 'Examination of oestrus-dependent alterations of bovine cervico-vaginal mucus glycosylation for potential as optimum fertilisation indicators' by Marie Le Berre et al., Mol. Omics, 2021, 17, 338-346, DOI: 10.1039/D0MO00193G.

An integrative network analysis framework for identifying molecular functions in complex disorders examining major depressive disorder as a test case.

In addition to the psychological depressive phenotype, major depressive disorder (MDD) patients are also associated with underlying immune dysregulation that correlates with metabolic syndrome prevalent in depressive patients. A robust integrative analysis of biological pathways underlying the dysregulated neural connectivity and systemic inflammatory response will provide implications in the development of effective strategies for the diagnosis, management and the alleviation of associated comorbidities. In the current study, focusing on MDD, we explored an integrative network analysis methodology to analyze transcriptomic data combined with the meta-analysis of biomarker data available throughout public databases and published scientific peer-reviewed articles. Detailed gene set enrichment analysis and complex protein-protein, gene regulatory and biochemical pathway analysis has been undertaken to identify the functional significance and potential biomarker utility of differentially regulated genes, proteins and metabolite markers. This integrative analysis method provides insights into the molecular mechanisms along with key glycosylation dysregulation underlying altered neutrophil-platelet activation and dysregulated neuronal survival maintenance and synaptic functioning. Highlighting the significant gap that exists in the current literature, the network analysis framework proposed reduces the impact of data gaps and permits the identification of key molecular signatures underlying complex disorders with multiple etiologies such as within MDD and presents multiple treatment options to address their molecular dysfunction.

Burkholderia cenocepacia BCAM2418-induced antibody inhibits bacterial adhesion, confers protection to infection and enables identification of host glycans as adhesin targets.

Trimeric Autotransporter Adhesins (TAA) found in Gram-negative bacteria play a key role in virulence. This is the case of Burkholderia cepacia complex (Bcc), a group of related bacteria able to cause infections in patients with cystic fibrosis. These bacteria use TAAs, among other virulence factors, to bind to host protein receptors and their carbohydrate ligands. Blocking such contacts is an attractive approach to inhibit Bcc infections. In this study, using an antibody produced against the TAA BCAM2418 from the epidemic strain Burkholderia cenocepacia K56-2, we were able to uncover its roles as an adhesin and the type of host glycan structures that serve as recognition targets. The neutralisation of BCAM2418 was found to cause a reduction in the adhesion of the bacteria to bronchial cells and mucins. Moreover, in vivo studies have shown that the anti-BCAM2418 antibody exerted an inhibitory effect during infection in Galleria mellonella. Finally, inferred by glycan arrays, we were able to predict for the first time, host glycan epitopes for a TAA. We show that BCAM2418 favoured binding to 3'sialyl-3-fucosyllactose, histo-blood group A, α-(1,2)-linked Fuc-containing structures, Lewis structures and GM1 gangliosides. In addition, the glycan microarrays demonstrated similar specificities of Burkholderia species for their most intensely binding carbohydrates.

Examination of oestrus-dependent alterations of bovine cervico-vaginal mucus glycosylation for potential as optimum fertilisation indicators.

Oestrus is the period in the sexual cycle of female mammals where they become most receptive to mating and are most fertile. Efficient detection of oestrus is a key component in successful reproductive livestock management programmes. Oestrus detection in cattle is most often performed by visual observation, such as mounting behaviour and standing heat, to facilitate more successful prediction of optimal time points for artificial insemination. This time-consuming method requires a skilled, diligent observer. Biological measurements using easily accessible biomolecules in the cervico-vaginal mucus could provide an alternative strategy to physical methods of oestrus detection, providing an inexpensive means of rapidly and accurately assessing the onset of oestrus. In this study, glycosylation changes in cervico-vaginal mucus from three heifers following oestrus induction were investigated as a proof of concept to assess whether potential glycosylation-based trends could be useful for oestrus stage indication. Mucus collected at different time points following oestrus induction was immobilised in a microarray format and its glycosylation interrogated with a panel of fluorescently labelled lectins, carbohydrate-binding proteins with different specificities. Individual animal-specific glycosylation patterns were observed, however each pattern followed a similar trend around oestrus. This unique oestrus-associated glycosylation was identified by a combination of relative binding of the lectins SNA-I and WFA for each animal. This alteration in cervico-vaginal mucus glycosylation could potentially be exploited in future to more accurately identify optimal fertilisation intervention points compared to visual signs. More effective oestrus biomarkers will lead to more successful livestock reproductive programmes, decreasing costs and animal stress.

Transcriptomic Analysis of Respiratory Tissue and Cell Line Models to Examine Glycosylation Machinery during SARS-CoV-2 Infection.

Glycosylation, being the most abundant post-translational modification, plays a profound role affecting expression, localization and function of proteins and macromolecules in immune response to infection. Presented are the findings of a transcriptomic analysis performed using high-throughput functional genomics data from public repository to examine the altered transcription of the human glycosylation machinery in response to SARS-CoV-2 stimulus and infection. In addition to the conventional in silico functional enrichment analysis methods we also present results from the manual analysis of biomedical literature databases to bring about the biological significance of glycans and glycan-binding proteins in modulating the host immune response during SARS-CoV-2 infection. Our analysis revealed key immunomodulatory lectins, proteoglycans and glycan epitopes implicated in exerting both negative and positive downstream inflammatory signaling pathways, in addition to its vital role as adhesion receptors for SARS-CoV-2 pathogen. A hypothetical correlation of the differentially expressed human glycogenes with the altered host inflammatory response and the cytokine storm-generated in response to SARS-CoV-2 pathogen is proposed. These markers can provide novel insights into the diverse roles and functioning of glycosylation pathways modulated by SARS-CoV-2, provide avenues of stratification, treatment, and targeted approaches for COVID-19 immunity and other viral infectious agents.

Genome, Environment, Microbiome and Metabolome in Autism (GEMMA) Study Design: Biomarkers Identification for Precision Treatment and Primary Prevention of Autism Spectrum Disorders by an Integrated Multi-Omics Systems Biology Approach.

Autism Spectrum Disorder (ASD) affects approximately 1 child in 54, with a 35-fold increase since 1960. Selected studies suggest that part of the recent increase in prevalence is likely attributable to an improved awareness and recognition, and changes in clinical practice or service availability. However, this is not sufficient to explain this epidemiological phenomenon. Research points to a possible link between ASD and intestinal microbiota because many children with ASD display gastro-intestinal problems. Current large-scale datasets of ASD are limited in their ability to provide mechanistic insight into ASD because they are predominantly cross-sectional studies that do not allow evaluation of perspective associations between early life microbiota composition/function and later ASD diagnoses. Here we describe GEMMA (Genome, Environment, Microbiome and Metabolome in Autism), a prospective study supported by the European Commission, that follows at-risk infants from birth to identify potential biomarker predictors of ASD development followed by validation on large multi-omics datasets. The project includes clinical (observational and interventional trials) and pre-clinical studies in humanized murine models (fecal transfer from ASD probands) and in vitro colon models. This will support the progress of a microbiome-wide association study (of human participants) to identify prognostic microbiome signatures and metabolic pathways underlying mechanisms for ASD progression and severity and potential treatment response.

Correction: Smac mimetic suppresses tunicamycin-induced apoptosis via resolution of ER stress.

Since online publication of this article, the authors noticed that Fig. 3b does not show the correct graph for Bortezomib. The corrected graph for Fig. 3b is provided below. This unintentional mistake does not alter the conclusions of the study. The authors apologise for any inconvenience caused.

Fasciola hepatica Extracellular Vesicles isolated from excretory-secretory products using a gravity flow method modulate dendritic cell phenotype and activity.

Parasite-released extracellular vesicles (EVs) deliver signals to the host immune system that are critical to maintaining the long-term relationship between parasite and host. In the present study, total EVs (FhEVs) released in vitro by adults of the helminth parasite Fasciola hepatica were isolated using a recently described gravity flow method that protects their structural integrity. The FhEVs molecular cargo was defined using proteomic analysis and their surface topology characterised by glycan microarrays. The proteomic analysis identified 618 proteins, 121 of which contained putative N-linked glycosylation sites while 132 proteins contained putative O-linked glycosylation sites. Glycan arrays revealed surface-exposed glycans with a high affinity for mannose-binding lectins indicating the predominance of oligo mannose-rich glycoproteins, as well as other glycans with a high affinity for complex-type N-glycans. When added to bone-marrow derived dendritic cells isolated FhEV induced a novel phenotype that was categorised by the secretion of low levels of TNF, enhanced expression of cell surface markers (CD80, CD86, CD40, OX40L, and SIGNR1) and elevation of intracellular markers (SOCS1 and SOCS3). When FhEV-stimulated BMDCs were introduced into OT-II mice by adoptive transfer, IL-2 secretion from skin draining lymph nodes and spleen cells was inhibited in response to both specific and non-specific antigen stimulation. Immunisation of mice with a suspension of FhEV did not elicit significant immune responses; however, in the presence of alum, FhEVs induced a mixed Th1/Th2 immune response with high antigen specific antibody titres. Thus, we have demonstrated that FhEVs induce a unique phentotype in DC capable of suppressing IL-2 secretion from T-cells. Our studies add to the growing immuno-proteomic database that will be an important source for the discovery of future parasite vaccines and immunotherapeutic biologicals.

Effects of Exogenous Dietary Advanced Glycation End Products on the Cross-Talk Mechanisms Linking Microbiota to Metabolic Inflammation.

Heat-processed diets contain high amounts of advanced glycation end products (AGEs). Here we explore the impact of an AGE-enriched diet on markers of metabolic and inflammatory disorders as well as on gut microbiota composition and plasma proteins glycosylation pattern. C57BL/6 mice were allocated into control diet (CD, n = 15) and AGE-enriched diet (AGE-D, n = 15) for 22 weeks. AGE-D was prepared replacing casein by methylglyoxal hydroimidazolone-modified casein. AGE-D evoked increased insulin and a significant reduction of GIP/GLP-1 incretins and ghrelin plasma levels, altered glucose tolerance, and impaired insulin signaling transduction in the skeletal muscle. Moreover, AGE-D modified the systemic glycosylation profile, as analyzed by lectin microarray, and increased Nε-carboxymethyllysine immunoreactivity and AGEs receptor levels in ileum and submandibular glands. These effects were associated to increased systemic levels of cytokines and impaired gut microbial composition and homeostasis. Significant correlations were recorded between changes in bacterial population and in incretins and inflammatory markers levels. Overall, our data indicates that chronic exposure to dietary AGEs lead to a significant unbalance in incretins axis, markers of metabolic inflammation, and a reshape of both the intestinal microbiota and plasma protein glycosylation profile, suggesting intriguing pathological mechanisms underlying AGEs-induced metabolic derangements.

A Whey Fraction Rich in Immunoglobulin G Combined with Bifidobacterium longum subsp. infantis ATCC 15697 Exhibits Synergistic Effects against Campylobacter jejuni.

Evidence that whey proteins and peptides have health benefits beyond basic infant nutrition has increased dramatically in recent years. Previously, we demonstrated that a whey-derived immunoglobulin G-enriched powder (IGEP) enhanced adhesion of Bifidobacterium longum subsp. infantis ATCC 15697 (B. infantis) to HT-29 cells. In this study, we investigated the synergistic effect of IGEP-treated B. infantis on preventing the attachment of highly invasive Campylobacter jejuni 81-176 (C. jejuni) to intestinal HT-29 cells. The combination decreased the adherence of C. jejuni to the HT-29 cells by an average of 48% compared to the control (non-IGEP-treated B. infantis). We also confirmed that treatment of IGEP with sodium metaperiodate, which disables the biological recognition of the conjugated oligosaccharides, reduced adhesion of B. infantis to the intestinal cells. Thus, glycosylation of the IGEP components may be important in enhancing B. infantis adhesion. Interestingly, an increased adhesion phenotype was not observed when B. infantis was treated with bovine serum-derived IgG, suggesting that bioactivity was unique to milk-derived immunoglobulin-rich powders. Notably, IGEP did not induce growth of B. infantis within a 24 hours incubation period, as demonstrated by growth curves and metabolite analysis. The current study provides insight into the functionality of bovine whey components and highlights their potential in positively impacting the development of a healthy microbiota.

Bifidobacterium longum subsp. infantis ATCC 15697 and Goat Milk Oligosaccharides Show Synergism In Vitro as Anti-Infectives against Campylobacter jejuni.

Bifidobacteria are known to inhibit, compete with and displace the adhesion of pathogens to human intestinal cells. Previously, we demonstrated that goat milk oligosaccharides (GMO) increased the attachment of Bifidobacterium longum subsp. infantis ATCC 15697 to intestinal cells in vitro. In this study, we aimed to exploit this effect as a mechanism for inhibiting pathogen association with intestinal cells. We examined the synergistic effect of GMO-treated B. infantis on preventing the attachment of a highly invasive strain of Campylobacter jejuni to intestinal HT-29 cells. The combination decreased the adherence of C. jejuni to the HT-29 cells by an average of 42% compared to the control (non-GMO treated B. infantis). Increasing the incubation time of the GMO with the Bifidobacterium strain resulted in the strain metabolizing the GMO, correlating with a subsequent 104% increase in growth over a 24 h period when compared to the control. Metabolite analysis in the 24 h period also revealed increased production of acetate, lactate, formate and ethanol by GMO-treated B. infantis. Statistically significant changes in the GMO profile were also demonstrated over the 24 h period, indicating that the strain was digesting certain structures within the pool such as lactose, lacto-N-neotetraose, lacto-N-neohexaose 3'-sialyllactose, 6'-sialyllactose, sialyllacto-N-neotetraose c and disialyllactose. It may be that early exposure to GMO modulates the adhesion of B. infantis while carbohydrate utilisation becomes more important after the bacteria have transiently colonised the host cells in adequate numbers. This study builds a strong case for the use of synbiotics that incorporate oligosaccharides sourced from goat's milk and probiotic bifidobacteria in functional foods, particularly considering the growing popularity of formulas based on goat milk.

Symposium review: Dairy-derived oligosaccharides-Their influence on host-microbe interactions in the gastrointestinal tract of infants.

Oligosaccharides are the third most abundant component in human milk. It is widely accepted that they play several important protective, physiological, and biological roles, including selective growth stimulation of beneficial gut microbiota, inhibition of pathogen adhesion, and immune modulation. However, until recently, very few commercial products on the market have capitalized on these functions. This is mainly because the quantities of human milk oligosaccharides required for clinical trials have been unavailable. Recently, clinical studies have tested the potential beneficial effects of feeding infants formula containing 2'-fucosyllactose, which is the most abundant oligosaccharide in human milk. These studies have opened this field for further well-designed studies, which are required to fully understand the role of human milk oligosaccharides. However, one of the most striking features of human milk is its diversity of oligosaccharides, with over 200 identified to date. It may be that a mixture of oligosaccharides is even more beneficial to infants than a single structure. For this reason, the milk of domestic animals has become a focal point in recent years as an alternative source of complex oligosaccharides with associated biological activity. This review will focus specifically on free oligosaccharides found in bovine and caprine milk and the biological roles associated with such structures. These dairy streams are ideal sources of oligosaccharides, given their wide availability and use in so many regularly consumed dairy products. The aim of this review was to provide an overview of research into the functional role of bovine and caprine milk oligosaccharides in host-microbial interactions in the gut and provide current knowledge related to the isolation of oligosaccharides as ingredients for incorporation in functional or medical foods.