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Abstract Peyer's patches are known as the immune sensors of the intestine because of their ability to transport luminal antigens. The objective of this study was both to assess the prenatal and postnatal development of sheep ileal Peyer's patches with respect to histomorphology, distribution of CD4+ and CD8+ cells, and localization of proliferating and apoptotic cells, and to examine the morphology of M cells and expression of CK18 in follicle associated epithelium (FAE). We also hypothesized that CK18 could be a potential marker for M cell. Peyer's patches completed their histomorphological development in prenatal period and involuted in the postnatal period. The distribution of the CD4+ and CD8+ cells was similar in the last trimester of pregnancy (days 120–150) and the postnatal period, but differed in the early stages of foetal development (days 70–120). In the prenatal period, the follicular area displayed high levels of proliferation and apoptosis. We observed CK18 immunoreaction only in FAE. While M cells were devoid of microfolds in the early stages of the prenatal period, these cells acquired a prismatic shape and bore distinct apical microfolds in the late prenatal period and postnatal period. As a result, it was determined that, in sheep, the development of the ileal Peyer's patches occurred in the prenatal period, independent of exogenous antigenic stimulation, and in association with high levels of lymphopoiesis and apoptosis in the follicles. We found, for the first time, that CK18 is a novel and reliable marker for FAE in sheep ileal Peyer's patches. We suggest that CK18 positive cells in FAE are M cells. [ABSTRACT FROM AUTHOR]

Fetal alcohol spectrum disorders (FASD) are associated with social interaction behavior and gastrointestinal (GI) abnormalities. These abnormal behaviors and GI abnormalities overlap with autism spectrum disorder (ASD). We investigated the effect of fetal alcohol exposure (FAE) on social interaction deficits (hallmark of autism) in mice. Evidence indicates that exogenous lipopolysaccharide (LPS) administration during gestation induces autism-like behavior in the offspring. LPS regulates the expression of genes underlying differentiation, immune function, myelination, and synaptogenesis in fetal brain by the LPS receptor, TLR-4-dependent mechanism. In this study, we evaluated the role of TLR-4 in FAE-induced social behavior deficit. WT and TLR4-/- pregnant mice were fed Lieber-DeCarli liquid diet with or without ethanol. The control group was pair-fed with an isocaloric diet. Social behavior was tested in the adult offspring at postnatal day 60. Frontal cortex mRNA expression of autistic candidate genes (Ube3a, Gabrb3, Mecp2) and inflammatory cytokine genes (IL-1β, IL-6, TNF-α) were measured by RT-qPCR. Adult male offspring of ethanol-fed WT dams showed low birth weight compared to offspring of pair-fed WT dams. However, their body weights at adulthood were greater compared to the body weights of offspring of pair-fed WT dams. There were no body weight differences in offspring of TLR4-/- dams. Social interaction deficit was observed only in male offspring of ethanol-fed WT dams, but it was not observed in both male and female offspring of ethanol-fed TLR4-/- dams. Expressions of autism candidate genes, Gabrb3 and Ube3a, were elevated, while that of the Mecp2 gene was suppressed in the frontal cortex of male, but not female, offspring of ethanol-fed WT mice. The expressions of inflammatory cytokine genes, IL-1β, IL-6, and TNF-α, were also significantly increased in the frontal cortex of male, but not female, offspring of ethanol-fed dams. The changes in the expression of autistic and cytokine genes were unaffected in the offspring of ethanol-fed TLR4-/- dams. These data also indicate that TLR4 mediates FAE-induced changes in social interactions and gene expression in brain, suggesting that ethanol-induced LPS absorption from the maternal gut may be involved in gene expression changes in the fetal brain. [ABSTRACT FROM AUTHOR]

Abstract: M cells are located in the follicle associated epithelium (FAE) of Peyer''s patches (PPs) in the small intestine, where they mediate the uptake and transcytosis of luminal antigens to the underlying lymphoid tissue. Toll-like receptors (TLRs) have emerged as key mediators in the innate immune response by recognising pathogen associated molecular patterns (PAMPs) expressed by microorganisms. TLRs have previously been shown to be differentially expressed in the gastrointestinal tract. In this study PP were harvested from BALB/c mice. Ulex europaeus agglutinin 1 (UAE-1) positive M cells were isolated from FAE and the expression of TLR1–9 transcripts in M cells, FAE and villus epithelium (VE) was compared by quantitative real-time PCR. Transcripts for TLR1, TLR2 and TLR4 were found to be expressed at a high level in M cells in comparison to VE, with no transcripts being detected in the FAE. TLR3 and TLR6 were not found to be expressed in M cells or in the FAE. TLR5 and TLR7 were found to be expressed at a higher level in FAE compared to M cells. TLR9, which recognises unmethylated CpG DNA of bacteria and viruses and TLR8, which recognises ssRNA, were found to be preferentially expressed in M cells compared to FAE and VE. [Copyright &y& Elsevier]

Abstract: The precise distribution and expression of Toll-like receptor (TLR) 9 in gut-associated lymphoid tissues (GALTs) has not been elucidated. In this study, we investigated the expression pattern of TLR9 in adult and neonatal swine GALTs by real-time quantitative PCR, western blot, confocal laser microscopy and flow cytometric analysis. The swine TLR9 gene was preferentially expressed in adult Peyer''s patches (Pps) and mesenteric lymph nodes (MLNs), which contained approximately three times higher TLR9 than the spleen. Other tissues exhibited only weak expression of TLR9. In neonatal swine, elevated expression of TLR9 was detected only in MLNs. We firstly showed that highly expressive (TLR9+) cells were formed in Pps and MLNs. In addition, TLR9+ cells were present not only in immune cells such as dendritic cells and B cells but also in follicle-associated epithelia (FAE) including membranous cells (M cells) in Pps. These results suggest that Pps and MLNs provide the host defense with the ability to respond to a variety of bioactive oligonucleotides (ODNs) from bacteria at a conductive site of initial immune responses. [Copyright &y& Elsevier]