Background Maternal breast milk (MBM) is enriched in microRNAs, factors that regulate protein translation throughout the human body. MBM from mothers of term and preterm infants differ in nutrient, hormone, and bioactive factor composition, but the microRNA differences between these groups have not been compared. We hypothesized that gestational age at delivery influences microRNA in MBM, particularly microRNAs involved in immunologic and metabolic regulation. Methods MBM from mothers of premature infants (pMBM) obtained 3–4 weeks post-delivery was compared with MBM from mothers of term infants obtained at birth (tColostrum) and 3–4 weeks post-delivery (tMBM). The microRNA profile in lipid and skim fractions of each sample was evaluated with high-throughput sequencing. Results The expression profiles of nine microRNAs in lipid and skim pMBM differed from tMBM. Gene targets of these microRNAs were functionally related to elemental metabolism and lipid biosynthesis. The microRNA profile of tColostrum was also distinct from pMBM, but clustered closely with tMBM. Twenty-one microRNAs correlated with gestational age demonstrated limited relationships with method of delivery, but not other maternal infant factors. Conclusion Premature delivery results in a unique MBM microRNA profile with metabolic targets. This suggests preterm milk may have adaptive functions for growth in premature infants.

Background & AimsDefects in Paneth cell (PC) function are associated with microbial dysbiosis and intestinal inflammation. PC granules contain antimicrobial peptides, cytokines, and substantial stores of zinc (Zn). We hypothesized that Zn, transported into the granule through the Zn transporter (ZnT)2, is critical for signature PC functions.MethodsZnT2 was localized to PC granules using immunofluorescence and sucrose gradient fractionation in wild-type (wt) mice, and consequences of ZnT2 loss were characterized in ZnT2 knockout (ZnT2ko) mice. Terminal ilea were harvested for immunofluorescence, electron microscopy, and fluorescent imaging with the Zn reporter Zinpyr-1. Alterations in fecal microbiota were characterized using 16s ribosomal RNA sequencing. PC degranulation, bacterial translocation, cytokine response to Escherichia coli endotoxin lipopolysaccharide, crypt viability after exposure to the oxidant monochloramine (NH2Cl), and bactericidal activity of luminal contents of terminal ilea against enteropathogenic E coli were assessed.ResultsZnT2 was localized to the membrane of PC granules. In ZnT2ko mice, spontaneous degranulation was observed more frequently than among wt mice. Secretory granules were hypodense with less active lysozyme, and there was evidence of autophagosome accumulation and granule degradation in PCs from ZnT2ko mice. Gut microbiota of ZnT2ko mice were enriched in Bacteroidales S24-7 and relatively depleted of species commonly found in wt mice. Evidence of PC dysfunction in ZnT2ko mice included impaired granule secretion and increased inflammatory response to lipopolysaccharide, less bactericidal activity, and greater susceptibility to cell death from NH2Cl.ConclusionsZnT2 is critical for Zn import into PC granules, and the inability to import Zn leads to profound defects in PC function and uncoordinated granule secretion.

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Previous studies have shown that dendritic cells (DC) pulsed with T27K, an antigenic preparation derived from spherules (of Coccidioides posadasii), activate peripheral blood mononuclear cells (PBMC) from nonimmune subjects as well as from patients with disseminated coccidioidomycosis. In this study, we have assessed the interaction between human DC and C. posadasii spherules in order to better understand the initial response between Coccidioides and the human host. Whole autoclaved spherules induced lymphocyte transformation in PBMC obtained from immune but not from nonimmune donors. Immature DC (iDC) bound fluorescein isothiocyanate-labeled spherules in a time-and temperature-dependent manner. This binding was blocked by the addition of mannan, suggesting mannose receptor involvement in the DC-Coccidioides interaction. Binding was subsequently associated with ingestion and intracellular processing of spherules. Coculturing of spherules with iDC was associated with the development of mature DC that were morphologically, phenotypically, and functionally similar to those induced by tumor necrosis factor alpha and prostaglandin E 2 . Finally, spherules incubated with iDC induced activation of PBMC from nonimmune donors. These data indicate that human DC are capable of binding, internalizing, and presenting antigens from Coccidioides spherules and suggest that DC may play a critical early role in the formation of a cellular immune response in human coccidioidomycosis.

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Scope Greater than 68% of young infants are exposed to dietary zinc (Zn) levels that are higher than the Tolerable Upper Intake Limit. However, the consequences of excess dietary Zn during early life on intestinal function and host–microbe interactions are unknown. Methods and Results Neonatal mice are gavaged with 100 Zn µg d–1 from postnatal day (PN) 2 through PN10 and indices of intestinal function and host–microbe interactions are compared to unsupplemented mice. Excess dietary Zn causes oxidative stress, increases goblet cell number and mucus production, and are associated with increased intestinal permeability and systemic inflammation. Over 900 genes are differentially expressed; 413 genes display a fold‐change >1.60. The Gene Ontology Biological processes most significantly affected include biological adhesion, the immune system, metabolic processes, and response to stimulus. Key genes most highly and significantly upregulated include ALDH2, MT1, TMEM6, CDK20, and COX62b, while CALU, ST3GAL4, CRTC2, SLC28A2, and COMMA1 are downregulated. These changes are associated with a microbiome enriched in pathogenic taxa including Pseudomonadales and Campylobacter, and greater expression of bacterial stress response genes. Conclusion Excess dietary Zn may have unforeseen influences on epithelial signaling pathways, barrier function, and luminal ecology in the intestine that may have long‐term consequences on intestinal health.

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