Guts! Dietary modulation of innate defense

Necrotizing enterocolitis (NEC) is the most common gastro-intestinal emergency in the neonatal intensive care. The incidence of NEC ranges from 0.3 to 2.4 infants per 1000 live births, with nearly 70% of cases occurring in infants born at less than 36 weeks of gestation. The incidence of NEC varies, affecting 2-5% of all premature infants.[1] The overall mortality for NEC ranges from 10% to 50%.[2] Despite optimal medical and surgical management of NEC, infants that recover from the disease suffer from substantial morbidity, such as intestinal obstruction as a consequence of scarring, liver failure due to a prolonged requirement for total parenteral nutrition, short bowel syndrome with intestinal failure and associated nutritional deficiencies, and associated defects in growth and development.[3-4] Length of hospital stay in infants with surgical NEC and medically treated NEC exceeds those of controls by 60 days and 22 days respectively. Based on length of stay, the estimated total hospital charges for infants with surgical NEC in the USA averaged $186 200 in excess of those for controls and$73 700 more for infants with medical NEC. The yearly additional hospital charges for NEC were $216 666 per survivor.[5] Hence, NEC is a significant and growing health concern for prematurely born infants. The costs in the Netherlands are not exactly known, but will not be very different. As the number of preterm births has almost doubled over the past two decades in the Netherlands (Perinatale Registratie Nederland) and the United States (National Vital Statistics Report 2003), this burden will continue to increase. In addition, recently the national policy has changed into a more liberal approach to the lower limit of viability. More very immature infants (from a gestational age of 24 weeks onwards) will be given a chance to survive, with consequently more risk of developing NEC

Mucin Muc2 Deficiency and Weaning Influences the Expression of the Innate Defense Genes Reg3β, Reg3γ and Angiogenin-4

Background Mucin Muc2 is the structural component of the intestinal mucus layer. Absence of Muc2 leads to loss of this layer allowing direct bacterial-epithelial interactions. We hypothesized that absence of the mucus layer leads to increased expression of innate defense peptides. Specifically, we aimed to study the consequence of Muc2 deficiency (Muc2-/-) on the expression of regenerating islet-derived protein 3 beta (Reg3ß), regenerating islet-derived protein 3 gamma (Reg3¿), and angiogenin-4 (Ang4) in the intestine shortly before and after weaning. Methods Intestinal tissues of Muc2-/- and wild-type (WT) mice were collected at postnatal day 14 (P14, i.e. pre-weaning) and P28 (i.e. post-weaning). Reg3ß, Reg3¿, and Ang4 expression was studied by quantitative real-time PCR, Western-blot, in situ hybridization, and immunohistochemistry. Results Reg3ß and Reg3¿ were expressed by diverging epithelial cell types; namely enterocytes, Paneth cells, and goblet cells. Additionally, Ang4 expression was confined to Paneth cells and goblet cells. Expression of Reg3ß, Reg3¿, and Ang4 differed between WT and Muc2-/- mice before and after weaning. Interestingly, absence of Muc2 strongly increased Reg3ß and Reg3¿ expression in the small intestine and colon. Finally, morphological signs of colitis were only observed in the distal colon of Muc2-/- mice at P28, where and when expression levels of Reg3ß, Reg3¿, and Ang4 were the lowest. Conclusions Expression of Reg3 proteins and Ang4 by goblet cells point to an important role for goblet cells in innate defense. Absence of Muc2 results in up-regulation of Reg3ß and Reg3¿ expression, suggesting altered bacterial-epithelial signaling and an innate defense response in Muc2-/- mice. The inverse correlation between colitis development and Reg3ß, Reg3¿, and Ang4 expression levels might point toward a role for these innate defense peptides in regulating intestinal inflammatio

Virological and immunological correlates of HIV posttreatment control after temporal antiretroviral therapy during acute HIV infection

Objective:People with HIV rarely control viral replication after cessation of antiretroviral therapy (ART). We present a person with HIV with extraordinary posttreatment control (PTC) for over 23 years after temporary ART during acute HIV infection (AHI) leading to a new insight in factors contributing to PTC.Design/methods:Viral reservoir was determined by HIV qPCR, Intact Proviral DNA Assay, and quantitative viral outgrowth assay. Viral replication kinetics were determined in autologous and donor PBMC. IgG levels directed against HIV envelope and neutralizing antibodies were measured. Immune phenotyping of T cells and HIV-specific T-cell responses were analyzed by flow cytometry.Results:The case presented with AHI and a plasma viral load of 2.7 million copies/ml. ART was initiated 2 weeks after diagnosis and interrupted after 26 months. Replicating virus was isolated shortly after start ART. At 18 years after treatment interruption, HIV-DNA in CD4+T cells and low levels of HIV-RNA in plasma (<5 copies/ml) were detectable. Stable HIV envelope glycoprotein-directed IgG was present during follow-up, but lacked neutralizing activity. Strong antiviral CD8+T-cell responses, in particular targeting HIV-gag, were detected during 25 years follow-up. Moreover, we found a P255A mutation in an HLA-B∗44 : 02 restricted gag-epitope, which was associated with decreased replication.Conclusion:We describe an exceptional case of PTC, which is likely associated with sustained potent gag-specific CD8+T-cell responses in combination with a replication attenuating escape mutation in gag. Understanding the initiation and preservation of the HIV-specific T-cell responses could guide the development of strategies to induce HIV control

Cloning, annotation and developmental expression of the chicken intestinal MUC2 gene

Intestinal mucin 2 (MUC2) encodes a heavily glycosylated, gel-forming mucin, which creates an important protective mucosal layer along the gastrointestinal tract in humans and other species. This first line of defense guards against attacks from microorganisms and is integral to the innate immune system. As a first step towards characterizing the innate immune response of MUC2 in different species, we report the cloning of a full-length, 11,359 bp chicken MUC2cDNA, and describe the genomic organization and functional annotation of this complex, 74.5 kb locus. MUC2 contains 64 exons and demonstrates distinct spatiotemporal expression profiles throughout development in the gastrointestinal tract; expression increases with gestational age and from anterior to posterior along the gut. The chicken protein has a similar domain organization as the human orthologue, with a signal peptide and several von Willebrand domains in the N-terminus and the characteristic cystine knot at the C-terminus. The PTS domain of the chicken MUC2 protein spans ~1600 amino acids and is interspersed with four CysD motifs. However, the PTS domain in the chicken diverges significantly from the human orthologue; although the chicken domain is shorter, the repetitive unit is 69 amino acids in length, which is three times longer than the human. The amino acid composition shows very little similarity to the human motif, which potentially contributes to differences in the innate immune response between species, as glycosylation across this rapidly evolving domain provides much of the musical barrier. Future studies of the function of MUC2 in the innate immune response system in chicken could provide an important model organism to increase our understanding of the biological significance of MUC2 in host defense and highlight the potential of the chicken for creating new immune-based therapies

The microbiome and regulation of mucosal immunity

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106849/1/imm12231.pd

High-level integration of murine intestinal transcriptomics data highlights the importance of the complement system in mucosal homeostasis.

BACKGROUND: The mammalian intestine is a complex biological system that exhibits functional plasticity in its response to diverse stimuli to maintain homeostasis. To improve our understanding of this plasticity, we performed a high-level data integration of 14 whole-genome transcriptomics datasets from samples of intestinal mouse mucosa. We used the tool Centrality based Pathway Analysis (CePa), along with information from the Reactome database. RESULTS: The results show an integrated response of the mouse intestinal mucosa to challenges with agents introduced orally that were expected to perturb homeostasis. We observed that a common set of pathways respond to different stimuli, of which the most reactive was the Regulation of Complement Cascade pathway. Altered expression of the Regulation of Complement Cascade pathway was verified in mouse organoids challenged with different stimuli in vitro. CONCLUSIONS: Results of the integrated transcriptomics analysis and data driven experiment suggest an important role of epithelial production of complement and host complement defence factors in the maintenance of homeostasis

Impact of high fat diets, prebiotics and probiotics on gut microbiota and immune function, with relevance to elderly populations

According to WHO, the number of people over 60 years of age is set to rise to 2 billion by 2050. Dysbiosis of microbial composition and impaired immune function have been observed in elderly persons compared to younger adults. As a result, the aging population has a higher disease risk than other age groups. In addition, high fat intakes have been observed to exert negative effects on microbial composition and immune function in murine studies. Elderly people have higher fat intakes than recommended levels, and this may make them more vulnerable to disease risk. Therefore, the impact of high fat consumption on elderly populations may be of relevance. Prebiotics and probiotics have been shown to have positive effects on microbiota composition and immune function in the elderly. This review describes aged-related changes in gut microbiome of elderly persons. It will also summarise studies concerning the impact of prebiotics, probiotics and high fat diets on microbiota composition and immune function