Rotavirus (RV) is considered to be the most common cause of gastroenteritis among infants aged less than 5 years old. Human milk bioactive compounds have the ability to modulate the diarrheic process caused by several intestinal pathogens. This study aimed to evaluate the potential protective role of a specific human milk oligosaccharide, 2′-fucosyllactose (2′-FL), a mixture of the prebiotic short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides 9:1 (GOS/FOS) and their combination (2′-FL+GOS/FOS) on RV-induced diarrhea in suckling rats. The nutritional intervention was performed from the second to the sixteenth day of life by oral gavage and on day 5 an RV strain was orally administered to induce infection. Fecal samples were scored daily to assess the clinical pattern of severity, incidence and duration of diarrhea. Blood and tissues were obtained at day 8 and 16 in order to evaluate the effects on the epithelial barrier and the mucosal and systemic immune responses. In the assessment of severity, incidence and duration of diarrhea, both 2′-FL and GOS/FOS displayed a beneficial effect in terms of amelioration. However, the mechanisms involved seemed to differ: 2′-FL displayed a direct ability to promote intestinal maturation and to enhance neonatal immune responses, while GOS/FOS induced an intestinal trophic effect and an RV-blocking action. The combination of 2′-FL and GOS/FOS showed additive effects in some variables. Therefore, it could be a good strategy to add these compounds in combination to infant formulas, to protect against human RV-induced diarrhea in children.

Human milk oligosaccharides are unconjugated complex glycans present in high concentration in human milk that serve as pre-biotics and immunomodulators. They are not primarily absorbed or metabolized by the infant and reach the lower part of the intestinal tract unaltered. One of the main oligosaccharides found in human milk is 2′-fucosyllactose (2′-FL). This study aimed to investigate the effects of daily oral administration of 2′-FL in healthy suckling rats. From days 2 to 16 of life, rats were daily given the oligosaccharide (2′-FL) or vehicle (REF), weighed and their stool characteristics were assessed. On days 8 and 16 of life the morphometry, intestinal architecture, and cytokine release, mesenteric lymph nodes cell composition, plasma immunoglobulin concentrations, fecal microbiota composition, cecal short-chain fatty acids content, and the urinary metabolic profile were assessed. Animals given 2′-FL showed higher plasma IgG and IgA and more T cell subsets in the mesenteric lymph nodes on day 16. Moreover, at intestinal level, villus heights, and areas were increased on day 8. Cecal samples displayed a higher Lactobacillus proportion and a different urinary metabolic profile was observed on day 8, and a higher proportion of butyrate on day 16. In conclusion, supplementation of 2′-FL in early life has a pre-biotic and intestinal trophic effect and promotes maturation of the immune system.

Breast milk components contribute to the infant’s immune development and protection, and among other immune factors, immunoglobulins (Igs) are the most studied. The presence of IgA in milk has been known for a long time; however, less information is available about the presence of other Igs such as IgM, IgG, and their subtypes (IgG1, IgG2, IgG3, and IgG4) or even IgE or IgD. The total Ig concentration and profile will change during the course of lactation; however, there is a great variability among studies due to several variables that limit establishing a clear pattern. In this context, the aim of this review was firstly to shed light on the Ig concentration in breast milk based on scientific evidence and secondly to study the main factors contributing to such variability. A search strategy provided only 75 studies with the prespecified eligibility criteria. The concentrations and proportions found have been established based on the intrinsic factors of the study—such as the sampling time and quantification technique—as well as participant-dependent factors, such as lifestyle and environment. All these factors contribute to the variability of the immunoglobulinome described in the literature and should be carefully addressed for further well-designed studies and data interpretation.