Expulsion of Trichuris muris is associated with increased expression of angiogenin 4 in the gut and increased acidity of mucins within the goblet cell

<p>Abstract</p> <p>Background</p> <p><it>Trichuris muris </it>in the mouse is an invaluable model for infection of man with the gastrointestinal nematode <it>Trichuris trichiura</it>. Three <it>T. muris </it>isolates have been studied, the Edinburgh (E), the Japan (J) and the Sobreda (S) isolates. The S isolate survives to chronicity within the C57BL/6 host whereas E and J are expelled prior to reaching fecundity. How the S isolate survives so successfully in its host is unclear.</p> <p>Results</p> <p>Microarray analysis was used as a tool to identify genes whose expression could determine the differences in expulsion kinetics between the E and S <it>T. muris </it>isolates. Clear differences in gene expression profiles were evident as early as day 7 post-infection (p.i.). 43 probe sets associated with immune and defence responses were up-regulated in gut tissue from an E isolate-infected C57BL/6 mouse compared to tissue from an S isolate infection, including the message for the anti-microbial protein, angiogenin 4 (Ang4). This led to the identification of distinct differences in the goblet cell phenotype post-infection with the two isolates.</p> <p>Conclusion</p> <p>Differences in gene expression levels identified between the S and E-infected mice early during infection have furthered our knowledge of how the S isolate persists for longer than the E isolate in the C57BL/6 mouse. Potential new targets for manipulation in order to aid expulsion have been identified. Further we provide evidence for a potential new marker involving the acidity of the mucins within the goblet cell which may predict outcome of infection within days of parasite exposure.</p

The Goblet Cell Is the Cellular Source of the Anti-Microbial Angiogenin 4 in the Large Intestine Post Trichuris muris Infection

Mouse angiogenin 4 (Ang4) has previously been described as a Paneth cell-derived antimicrobial peptide important in epithelial host defence in the small intestine. However, a source for Ang4 in the large intestine, which is devoid of Paneth cells, has not been defined.Analysis was performed on Ang4 expression in colonic tissue by qPCR and immunohistochemistry following infection with the large intestine dwelling helminth parasite Trichuris muris. This demonstrated an increase in expression of the peptide following infection of resistant BALB/c mice. Further, histological analysis of colonic tissue revealed the cellular source of this Ang4 to be goblet cells. To elucidate the mechanism of Ang4 expression immunohistochemistry and qPCR for Ang4 was performed on colonic tissue from T. muris infected mouse mutants. Experiments comparing C3H/HeN and C3H/HeJ mice, which have a natural inactivating mutation of TLR4, revealed that Ang4 expression is TLR4 independent. Subsequent experiments with IL-13 and IL-4 receptor alpha deficient mice demonstrated that goblet cell expression of Ang4 is controlled either directly or indirectly by IL-13.The cellular source of mouse Ang4 in the colon following T. muris infection is the goblet cell and expression is under the control of IL-13

The Innate Immune Responses of Colonic Epithelial Cells to Trichuris muris Are Similar in Mouse Strains That Develop a Type 1 or Type 2 Adaptive Immune Response

Trichuris muris resides in intimate contact with its host, burrowing within cecal epithelial cells. However, whether the enterocyte itself responds innately to T. muris is unknown. This study investigated for the first time whether colonic intestinal epithelial cells (IEC) produce cytokines or chemokines following T. muris infection and whether divergence of the innate response could explain differentially polarized adaptive immune responses in resistant and susceptible mice. Increased expression of mRNA for the proinflammatory cytokines gamma interferon (IFN-γ) and tumor necrosis factor and the chemokine CCL2 (MCP-1) were seen after infection of susceptible and resistant strains, with the only difference in expression being a delayed increase in CCL2 in BALB/c IEC. These increases were ablated in MyD88(−/−) mice, and NF-κB p65 was phosphorylated in response to T. muris excretory/secretory products in the epithelial cell line CMT-93, suggesting involvement of the MyD88-NF-κB signaling pathway in IEC cytokine expression. These data reveal that IEC respond innately to T. muris. However, the minor differences identified between resistant and susceptible mice are unlikely to underlie the subsequent development of a susceptible type 1 (IFN-γ-dominated) or resistant type 2 (interleukin-4 [IL-4]/IL-13-dominated) adaptive immune response

The p36 isoform of BAG-1 is translated by internal ribosome entry following heat shock

BAG-1 (also known as RAP46/HAP46) was originally identified as a 46 kDa protein that bound to and enhanced the anti-apoptotic properties of Bcl-2. BAG-1 exists as three major isoforms (designated p50, p46 and p36 or BAG-1L, BAG-1M and BAG-1S respectively) and one minor isoform (p29), which are translated from a common transcript. The differing amino terminus determines both the intracellular location and the repertoire of binding partners of the isoforms which play different roles in a variety of cellular processes including signal transduction, heat shock, apoptosis and transcription. Although in vitro data suggest that the four BAG-1 isoforms are translated by leaky scanning, the patterns of isoform expression in vivo, especially in transformed cells, do not support this hypothesis. We have performed in vivo analysis of the BAG-1 5' untranslated region and shown that translation initiation of the most highly expressed isoform (p36/BAG-1S) can occur by both internal ribosome entry and cap-dependent scanning. Following heat shock, when there is a downregulation of cap-dependent translation, the expression of the p36 isoform of BAG-1 is maintained by internal ribosome entry

Rapid dendritic cell mobilization to the large intestinal epithelium is associated with resistance to Trichuris muris infection

The large intestine is a major site of infection and disease, yet little is known about how immunity is initiated within this site and the role of dendritic cells (DCs) in this process. We used the well-established model of Trichuris muris infection to investigate the innate response of colonic DCs in mice that are inherently resistant or susceptible to infection. One day postinfection, there was a significant increase in the number of immature colonic DCs in resistant but not susceptible mice. This increase was sustained at day 7 postinfection in resistant mice when the majority of the DCs were mature. There was no increase in DC numbers in susceptible mice until day 13 postinfection. In resistant mice, most colonic DCs were located in or adjacent to the epithelium postinfection. There were also marked differences in the expression of colonic epithelial chemokines in resistant mice and susceptible mice. Resistant mice had significantly increased levels of epithelium-derived CCL2, CCL3, CCL5, and CCL20 compared with susceptible mice. Furthermore, administering neutralizing CCL5 and CCL20 Abs to resistant mice prevented DC recruitment. This study provides clear evidence of differences in the kinetics of DC responses in hosts inherently resistant and susceptible to infection. DC responses in the colon correlate with resistance to infection. Differences in the production of DC chemotactic chemokines by colonic epithelial cells in response to infection in resistant vs susceptible mice may explain the different kinetics of the DC response