molecular-profiling-invasive-tumor-microenvironment-3-dimensional

Molecular Profiling of the Invasive Tumor Microenvironment in a 3-Dimensional Model of Colorectal Cancer Cells and <em>Ex vivo</em> Fibroblasts

Invading colorectal cancer (CRC) cells have acquired the capacity to break free from their sister cells, infiltrate the stroma, and remodel the ...

University of Southampton School of Medicine

The indigenous bacterial microflora colonize the gut at birth and remain there throughout life. Approximately 10(14) bacteria are present in the ileum and colon and they are clearly immunogenic. The evidence is strong that the vast majority of IgA plasma cells in normal human gut are responding to the antigens of the flora, and although the flora is also responsible for producing the large numbers of T cells which are present in the gut of healthy individuals, the types of T cell response which the flora elicits are less well understood. A major challenge for the immune system is to distinguish between the antigens of the flora and the antigens of pathogens. There is also a growing realization that the normal flora can also influence gene expression in antigen-presenting cells in the gut and so set the context in which T cells respond to food antigen and vaccines.

Microbial-gut interactions in health and disease. Immune responses.

Infection of mice with the intestinal bacterial pathogen Citrobacter rodentium results in colonic mucosal hyperplasia and a local Th1 inflammatory response similar to that seen in mouse models of inflammatory bowel disease. Matrix metalloproteinases (MMPs) have been shown to mediate matrix remodeling and cell migration during tissue injury and repair in the intestine. We have previously shown enhanced pathology in infected TNFRp55-/-, IL-12p40-/-, and IFN-gamma-/- mice, and here we show that this is associated with an increase in stromelysin-1 (MMP3) transcripts in colonic tissues. We have therefore investigated the role of MMP3 in colonic mucosal hyperplasia and the local Th1 responses using MMP3-/- mice. In MMP3-/- mice, similar mucosal thickening was observed after infection as in wild-type (WT) mice. Colonic tissues from MMP3-/- mice showed a compensatory increase in the expression of other MMP transcripts, such as MMP7 and MMP12. However, MMP3-/- mice showed delayed clearance of bacteria and delayed appearance of CD4+ T lymphocytes into intestinal lamina propria. CSFE-labeled mesenteric lymph node CD4+ T lymphocytes from infected WT mice migrated in fewer numbers into the mesenteric lymph nodes and colon of MMP3-/- mice than into those of WT mice. These studies show that mucosal remodeling can occur in the absence of MMP3, but that MMP3 plays a role in the migration of CD4+ T lymphocytes to the intestinal mucosa.

Impaired immunity to intestinal bacterial infection in stromelysin-1 (matrix metalloproteinase-3)-deficient mice.

Citrobacter rodentium is a natural mouse pathogen related to enteropathogenic and enterohemorrhagic Escherichia coli. We have previously utilized bioluminescence imaging (BLI) to determine the in vivo colonization dynamics of C. rodentium. However, due to the oxygen requirement of the bioluminescence system and the colonic localization of C. rodentium, in vivo localization studies were performed using harvested organs. Here, we report the detection of bioluminescent C. rodentium and commensal E. coli during colonization of the gastrointestinal tract in intact living animals. Bioluminescence was dependent on intact blood circulation, suggesting that the colonic environment is not anaerobic but nanaerobic. In addition, BLI revealed that C. rodentium colonizes the rectum, a site previously unreported for this pathogen.

In vivo bioluminescence imaging of the murine pathogen Citrobacter rodentium.

Dendritic cells (DCs) play a crucial role in immune responses by controlling the extent and type of T-cell response to antigen. Celiac disease is a condition in which T-cell immunity to gluten plays an important pathogenic role, yet information on DCs is scant. We examined mucosal DCs in celiac disease in terms of phenotype, activation/maturation state, cytokine production, and function.

Evidence for the role of interferon-alfa production by dendritic cells in the Th1 response in celiac disease.

In both ulcerative colitis (UC) and Crohn's disease (CD) there is a marked increase in mucosal IgG plasma cells (PC), although their precise role is not well established. In this study we isolated gut PCs from patients with IBD and normal controls and analyzed cytokine production, matrix metalloproteinase (MMP)-3 and tissue inhibitor of metalloproteinase (TIMP)-1 production, and PC longevity ex vivo.

Article	Year
Microbial-gut interactions in health and disease. Immune responses. Best practice & research. Clinical gastroenterology\| PubMed ID: 15123069	2004
Impaired immunity to intestinal bacterial infection in stromelysin-1 (matrix metalloproteinase-3)-deficient mice. Journal of immunology (Baltimore, Md. : 1950)\| PubMed ID: 15470062	2004
In vivo bioluminescence imaging of the murine pathogen Citrobacter rodentium. Infection and immunity\| PubMed ID: 16926434	2006
Evidence for the role of interferon-alfa production by dendritic cells in the Th1 response in celiac disease. Gastroenterology\| PubMed ID: 17919493	2007
Matrix metalloproteinase-3 production by gut IgG plasma cells in chronic inflammatory bowel disease. Inflammatory bowel diseases\| PubMed ID: 18022869	2008

Karen M. Pickard

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