Rodriguez-Camejo, C. | Search bioRxiv

bioRxiv2025

Links Between Gut Microbiota of Uruguayan Infants, Breast Milk Composition, and Maternal Factors During Exclusive Breastfeeding

BackgroundGiven the links between early gut microbiota, breastfeeding, and maternal physiology, we characterized the intestinal microbiota of infants during exclusive breastfeeding (mean=5.4 months), examining its associations with breastmilk composition, fecal IgA, and maternal factors in Uruguayan primiparous mothers, with vaginal (V, n=20) or cesarean-section delivery (CS, n=14). MethodsWe analyzed fecal microbiota via 16S rRNA V4 sequencing and quantified stool IgA, breastmilk components (antibodies, hormones, macronutrients) using ELISA and standard biochemical methods. ResultsPrincipal Coordinates Analysis showed separation by delivery mode (PCo1:44.6%, PCo2:14.2%). Samples of CS-group displayed lower relative abundance (RA %) of Bacteroidetes/Firmicutes ratio, higher RA of Proteobacteria (50.7%vs35.5%), and decreased Bacteroides (2.5%vs31.8%) than V-group. Biochemical parameters didnt differ between groups. In the V-group, milk and fecal IgA correlated (r=+0.47), as did Bifidobacterium RA with milk IgA (r=+0.47). Fat content was associated with different microbial taxa in both groups. Only in CS-group milk carbohydrates correlated with Bifidobacterium (r=-0.679) and maternal stress with Flavonifractor in CS-group (r=+0.461). ConclusionResults indicate delivery mode can exert persistent impact on infant gut microbiota until the introduction of complementary feeding. Differences in correlation patterns between groups suggest distinct regulatory mechanisms of microbiota, possibly linked to physiological processes that differ according to delivery mode. ImpactO_LIThis is the first study to assess the gut microbiota composition of exclusively breastfed infants born to Uruguayan mothers, in parallel with analyses of breast milk composition and maternal perceived stress C_LIO_LIThe mode of delivery was associated with differences in gut microbiota composition at a mean age of 5.4 months. C_LIO_LIDifferent associations between milk composition and maternal perceived stress with predominant microbial taxa were found according to the type of delivery. C_LIO_LIThese findings provide a basis for studies on microbiota regulatory mechanisms influenced by maternal physiology according to delivery mode C_LI

genomics↗

bioRxiv2025

Differential effects of postpartum sleep restriction on maternal and offspring immunity in the rat

Backgroundsleep disturbances can trigger a wide range of physiological consequences, affecting hormonal regulation, metabolism, cognitive function, and immune responses. Human mothers worldwide frequently experience sleep restriction and fragmentation, a pattern also observed in other mammalian mothers, such as rats. These alterations may add to sleep disturbances unrelated to motherhood. Considering this, we wondered about the impact of sleep restriction in postpartum mother rats on their immunological status. Furthermore, given that early-life experiences can shape the immune system and that even subtle parental changes can influence offspring development, we hypothesized that maternal sleep loss might also exert detrimental effects on the pups. In this study, we investigated the effects of acute and chronic maternal sleep restriction during the postpartum period on immune parameters in both mother rats and their offspring by analyzing antibody titers and systemic inflammation. Methodsmother rats were surgically implanted with electrodes for polysomnographic recordings and for sleep deprivation (deep electrodes targeting the mesopontine wake-promoting area). From postpartum day 5 to day 9, lactating dams were randomly assigned to one of three groups: chronic sleep restriction (CSR; 6 h of sleep deprivation per day for five consecutive days), acute sleep restriction (ASR; 6 h of sleep deprivation only on postpartum day 9), or control (undisturbed). On postpartum day 9, mothers were milked, and blood samples from both mothers and pups were subsequently collected. ELISA assays quantified IL-17A, IL-6, IgG, and IgG2a in maternal serum; IgG and IgG2a in milk; and IgG in pup serum. Hematological parameters, including leukocyte profiles, were also assessed in peripheral blood of dams and pups. Resultsmaternal immune parameters analyzed remained unaffected by sleep restriction. IgG levels were lower in male pups from mothers subjected to ASR (5560 {+/-} 734 {micro}g/mL) compared with the control group (8666 {+/-} 463 {micro}g/mL; p = 0.025), whereas female pups showed no significant changes. Additionally, both female (4.10 {+/-} 0.58) and male (3.81 {+/-} 0.42) pups from dams subjected to CSR exhibited higher absolute lymphocytes counts relative to the control group (females: 2.28 {+/-} 0.25, p = 0.004; males: 2.44 {+/-} 0.25; p = 0.029). ConclusionsChronic and acute maternal sleep restriction had distinct impacts on offspring immunity, altering serum antibody and leukocyte profiles, while leaving maternal parameters unaffected. These results indicate that maternal sleep loss can influence the offspring even in the absence of detectable maternal immune alterations, with male pups being especially susceptible.

immunology↗