Abnormal expression of CEACAM6 is observed at the apical surface of the ileal epithelium in Crohn's disease (CD) patients, and CD ileal lesions are colonized by pathogenic adherent-invasive Escherichia coli (AIEC). We investigated the ability of AIEC reference strain LF82 to colonize the intestinal mucosa and to induce inflammation in CEABAC10 transgenic mice expressing human CEACAMs. AIEC LF82 virulent bacteria, but not nonpathogenic E. coli K-12, were able to persist in the gut of CEABAC10 transgenic mice and to induce severe colitis with reduced survival rate, marked weight loss, increased rectal bleeding, presence of erosive lesions, mucosal inflammation, and increased proinflammatory cytokine expression. The colitis depended on type 1 pili expression by AIEC bacteria and on intestinal CEACAM expression because no sign of colitis was observed in transgenic mice infected with type 1 pili–negative LF82-ΔfimH isogenic mutant or in wild-type mice infected with AIEC LF82 bacteria. These findings strongly support the hypothesis that in CD patients having an abnormal intestinal expression of CEACAM6, AIEC bacteria via type 1 pili expression can colonize the intestinal mucosa and induce gut inflammation. Thus, targeting AIEC adhesion to gut mucosa represents a new strategy for clinicians to prevent and/or to treat ileal CD.

Infectious complications resulting from resection of colorectal cancer (CRC) elevates the risk of cancer recurrence and metastasis, but the reason for this risk relationship is unknown. Defining the mechanisms responsible may offer opportunities to improve outcomes in a majority of patients whose tumors are resected as part of their therapy. The complex formed between Toll receptor TLR4 and myeloid differentiation factor MD2 defines a major cell surface receptor for lipopolysaccharide (LPS), a gram-negative bacterial antigen that has been implicated in infectious complications after CRC resection. As the TLR4/MD2 complex is expressed on CRC cells, we hypothesized that LPS may promote liver metastasis in CRC by stimulating TLR4 signaling. In support of this hypothesis, we report here that LPS enhances liver metastasis of human CRC cells that express TLR4/MD2 after intrasplenic graft of immunocompromised nude mice. Compared with TLR4 nonexpressing, nonmetastatic CRC cells, we observed increased in vitro adherence to different extracellular matrices and human umbilical vein endothelial cells (HUVEC). Furthermore, we observed an increased likelihood of in vivo capture within hepatic sinusoids after LPS treatment. No differences were apparent in phosphorylation of p38 and MAPK isoforms, but in metastatic CRC cells expressing surface TLR4 treatment with LPS increased Ser473 phosphorylation of AKT kinase. We showed that enhanced adherence elicited by LPS in these cells could be blocked at three different levels, using Eritoran (TLR4 small molecule antagonist), PI-103 (PI3K inhibitor), or anti-b1 integrin blocking antibodies. Taken together, the results indicate that stimulation of the TLR4/MD2 complex by LPS activates PI3K/AKT signaling and promotes downstream b1 integrin function, thereby increasing the adhesiveness and metastatic capacity of CRC cells. Our findings suggest that inhibiting LPS-induced TLR4 signaling could improve therapeutic outcomes by preventing cancer metastasis during the perioperative period of CRC resection. Cancer Res; 71(5); 1989-98. Ó2011 AACR.

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Many novel cancer therapies, including immunotherapy and gene therapy, are specifically targeted to tumor-associated molecules, among which carcinoembryonic antigen (CEA) represents a popular example. Discrepancies between preclinical experimental data in animal models and clinical outcome in terms of therapeutic response and toxicity, however, often arise. Preclinical testing can be compromised by the lack of CEA and other closely related human CEA family members in rodents, which lack analogous genes for most human CEA family members. Here, we report the construction of a transgenic mouse with a 187-kb human bacterial artificial chromosome (CEABAC) that contains part of the human CEA family gene cluster including complete human CEA (CEACAM5), CEACAM3, CEACAM6, and CEACAM7 genes. The spatiotemporal expression pattern of these genes in the CEABAC mice was found to be remarkably similar to that of humans. This novel mouse will ensure better assessment than previously utilized models for the preclinical testing of CEA-targeted therapies and perhaps allow the testing of CEACAM6, which is overexpressed in many solid tumors and leukemias, as a therapeutic target. Moreover, expression of CEA family genes in gastrointestinal, breast, hematopoietic, urogenital, and respiratory systems could facilitate other clinical applications, such as the development of therapeutic agents against Neisseria gonorrhoeae infections, which use CEA family members as major receptors.

An overwhelming neutrophil-driven response causes both acute symptoms and the lasting sequelae that result from infection with Neisseria gonorrhoeae. Neutrophils undergo an aggressive opsonin-independent response to N. gonorrhoeae, driven by the innate decoy receptor CEACAM3. CEACAM3 is exclusively expressed by human neutrophils, and drives a potent binding, phagocytic engulfment and oxidative killing of Opa-expressing bacteria. In this study, we sought to explore the contribution of neutrophils to the pathogenic inflammatory process that typifies gonorrhea. Genome-wide microarray and biochemical profiling of gonococcal-infected neutrophils revealed that CEACAM3 engagement triggers a Syk-, PKCδ- and Tak1-dependent signaling cascade that results in the activation of an NF-κB-dependent transcriptional response, with consequent production of pro-inflammatory cytokines. Using an in vivo model of N. gonorrhoeae infection, we show that human CEACAM-expressing neutrophils have heightened migration toward the site of the infection where they may be further activated upon Opa-dependent binding. Together, this study establishes that the role of CEACAM3 is not restricted to the direct opsonin-independent killing by neutrophils, since it also drives the vigorous inflammatory response that typifies gonorrhea. By carrying the potential to mobilize increasing numbers of neutrophils, CEACAM3 thereby represents the tipping point between protective and pathogenic outcomes of N. gonorrhoeae infection.