A new model for studying eosinophil migration across cultured intestinal epithelial monolayers

Therapeutic efficacy and mechanism of water-soluble extracts of Banxiaxiexin decoction on BALB/c mice with oxazolone-induced colitis

The aim of the present study was to investigate the therapeutic effects of water-soluble extracts of Banxiaxiexin decoction, a classical traditional Chinese medicine formulation, on BALB/c mice with experimentally induced ulcerative colitis (UC). Water-soluble extracts of Banxiaxiexin decoction were intragastrically administered to BALB/c mice with oxazolone (OXA)-induced colitis. Sulfasalazine (SASP) was administered intragastrically to OXA-treated mice to establish the SASP group (positive control). Following drug administration, the disease activity index (DAI) and the histopathological inflammation score were recorded. In addition, the expression levels of interleukin (IL)-5 and IL-13 mRNA in the colonic tissue were determined by fluorescent quantitative polymerase chain reaction. The DAI and histopathological inflammation score of the model group were significantly greater compared with those of the control group, and the mRNA expression levels of IL-5 and IL-13 in the colonic tissue were also significantly higher in the model group compared with those in the control group. The intragastric administration of water-soluble extracts of Banxiaxiexin decoction significantly lowered the DAI and histopathological inflammation score. The mRNA expression levels of IL-5 and IL-13 in the colonic tissue were also significantly lowered. The therapeutic effect of Banxiaxiexin decoction was found to be comparable to that of SASP. In conclusion, the results from the present study demonstrate that water-soluble extracts of the traditional Chinese medicine formulation Banxiaxiexin decoction have a therapeutic effect on BALB/c mice with OXA-induced colitis.

Functional consequences of prolactin signalling in endothelial cells: a potential link with angiogenesis in pathophysiology?

Prolactin is best known as the polypeptide anterior pituitary hormone, which regulates the development of the mammary gland. However, it became clear over the last decade that prolactin contributes to a broad range of pathologies, including breast cancer. Prolactin is also involved in angiogenesis via the release of pro-angiogenic factors by leukocytes and epithelial cells. However, whether prolactin also influences endothelial cells, and whether there are functional consequences of prolactin-induced signalling in the perspective of angiogenesis, remains so far elusive. In the present study, we show that prolactin induces phosphorylation of ERK1/2 and STAT5 and induces tube formation of endothelial cells on Matrigel. These effects are blocked by a specific prolactin receptor antagonist, del1-9-G129R-hPRL. Moreover, in an in vivo model of the chorioallantoic membrane of the chicken embryo, prolactin enhances vessel density and the tortuosity of the vasculature and pillar formation, which are hallmarks of intussusceptive angiogenesis. Interestingly, while prolactin has only little effect on endothelial cell proliferation, it markedly stimulates endothelial cell migration. Again, migration was reverted by del1-9-G129R-hPRL, indicating a direct effect of prolactin on its receptor. Immunohistochemistry and spectral imaging revealed that the prolactin receptor is present in the microvasculature of human breast carcinoma tissue. Altogether, these results suggest that prolactin may directly stimulate angiogenesis, which could be one of the mechanisms by which prolactin contributes to breast cancer progression, thereby providing a potential tool for intervention.

Chemoattractant-induced signaling via the Ras-ERK and PI3K-Akt networks, along with leukotriene C4 release, is dependent on the tyrosine kinase Lyn in IL-5- and IL-3-primed human blood eosinophils

Human blood eosinophils exhibit a hyperactive phenotype in response to chemotactic factors after cell "priming" with IL-5 family cytokines. Earlier work has identified ERK1/2 as molecular markers for IL-5 priming, and in this article, we show that IL-3, a member of the IL-5 family, also augments fMLP-stimulated ERK1/2 phosphorylation in primary eosinophils. Besides ERK1/2, we also observed an enhancement of chemotactic factor-induced Akt phosphorylation after IL-5 priming of human blood eosinophils. Administration of a peptide antagonist that targets the Src family member Lyn before cytokine (IL-5/IL-3) priming of blood eosinophils inhibited the synergistic increase of fMLP-induced activation of Ras, ERK1/2 and Akt, as well as the release of the proinflammatory factor leukotriene C(4). In this study, we also examined a human eosinophil-like cell line HL-60 clone-15 and observed that these cells exhibited significant surface expression of IL-3Rs and GM-CSFRs, as well as ERK1/2 phosphorylation in response to the addition of IL-5 family cytokines or the chemotactic factors fMLP, CCL5, and CCL11. Consistent with the surface profile of IL-5 family receptors, HL-60 clone-15 recapitulated the enhanced fMLP-induced ERK1/2 phosphorylation observed in primary blood eosinophils after priming with IL-3/GM-CSF, and small interfering RNA-mediated knockdown of Lyn expression completely abolished the synergistic effects of IL-3 priming on fMLP-induced ERK1/2 phosphorylation. Altogether, our data demonstrate a central role for Lyn in the mechanisms of IL-5 family priming and suggest that Lyn contributes to the upregulation of the Ras-ERK1/2 and PI3K-Akt cascades, as well as the increased leukotriene C(4) release observed in response to fMLP in "primed" eosinophils.

Exacerbation of oxazolone colitis by infection with the helminth Hymenolepis diminuta: involvement of IL-5 and eosinophils

Substantial data show that infection with helminth parasites ameliorates colitis; however, oxazolone-induced colitis is exaggerated in mice infected with the tapeworm, Hymenolepis diminuta. We tested the hypothesis that the IL-5 response to helminth infection enhances the severity of oxazolone-induced colitis. Mice were infected with H. diminuta and 8 days later were treated with oxazolone ± anti-IL-5 antibodies. Colitis was assessed 72 hours postoxazolone treatment by disease activity scores, myeloperoxidase activity, and histopathology. Other mice received injections of a replication-deficient adenovirus that carried the IL-5 (Ad.IL-5) gene or a control adenovirus (Ad.delete) ± oxazolone. The effect of H. diminuta+oxazolone in CCL11/CCL22 (eotaxin-1 and 2) knockout (KO) mice was determined. Helminth infection and Ad.IL-5 treatment increased IL-5 and eosinophil numbers. In vivo neutralization of IL-5 significantly reduced the severity of colitis in H. diminuta+oxazolone-treated mice, and H. diminuta did not exaggerate oxazolone-induced colitis in CCL11/CCL22 KO mice. Mice receiving Ad.IL-5 only had no colitis, while oxazolone-induced colitis was more severe in animals cotreated with Ad.IL-5 (Ad.delete + oxazolone was not significantly different from oxazolone only). Thus, while there is much to be gleaned about antiinflammatory mechanisms from rodent-helminth model systems, these data illustrate the caveat that infection with helminth parasites as a therapy could be contraindicated in patients with eosinophilia or elevated IL-5 unless coupled to appropriate measures to block IL-5 and/or eosinophil activity.

Coagulation factor Xa inhibits cancer cell migration via protease-activated receptor-1 activation

Cell migration is critically important in (patho)physiological processes. The metastatic potential of cancer cells partly depends on activation of the coagulation cascade. The aim of the present study was to determine whether coagulation factor X (FXa) can regulate the migration and invasion of cancer cells. Quite unexpectedly, we found that FXa markedly diminished the migration of different cancer cell lines of various origins (breast, lung and colon cancer cells). We showed that FXa mediated inhibition of cancer cell migration was specific, as it was inhibited by TAP (a specific FXa inhibitor) but not by Hirudin (a specific thrombin inhibitor). Moreover, the FXa effect was dose dependent, with a maximal inhibitory effect reached at 0.75 U/ml FXa (corresponding to 130.5 nM). Next, we determined that FXa acted via protease-activated receptor (PAR)-1-dependent signaling, and PAR-1 desensitization, as well as knocking-down PAR-1 expression, abolished the FXa effects. Finally, we showed that Gialpha was not involved in FXa mediated inhibition of cell migration as its effects were not reverted by pertussis toxin. These results suggest that, beyond its role in blood coagulation, FXa plays a key role in cancer cell migration. They also shed light on an unexpected role of PAR-1, which appears to be a Janus-like receptor in cancer cell biology.

Gastroduodenal diseases of childhood

PURPOSE OF REVIEW

This paper will review new developments in the etiology and management of gastric and duodenal diseases affecting children.

RECENT FINDINGS

Despite dropping prevalence rates in developed nations, most new Helicobacter pylori infections are primarily acquired during childhood. Resistance to standard triple therapy and falling eradication rates are increasing problems for clinicians, necessitating the study of alternative treatment strategies. Eosinophilic diseases of the gastrointestinal tract are being increasingly recognized. Although population-based epidemiology and the natural history of eosinophilic diseases are not yet fully characterized, biologic therapies are in development for the treatment of these chronic, often refractory, conditions. A recent US National Institutes of Health celiac disease consensus conference suggested that infants' diet constituents and timing of solid food introduction are potential environmental influences in the development of celiac disease.

SUMMARY

New methods of diagnosis and treatment are greatly impacting care of pediatric patients with gastric and duodenal diseases. Less invasive but highly accurate tools for diagnosis are becoming better validated. Early diagnosis and effective intervention in most gastroduodenal disorders of childhood can alter natural history and improve overall quality of life.

Role of selectins in the intestinal epithelial migration of eosinophils

Understanding the mechanisms by which eosinophils migrate into and across the intestinal epithelium can provide alternative therapeutic targets for conditions characterized by eosinophilic cryptitis and crypt abscesses. Eosinophil migration is dependent on adhesion molecules such as selectins. Human eosinophils express L-selectin and P-selectin counterligand P-selectin glycoprotein ligand-1 (PSGL-1). The tetrasaccharide sialyl Lewis(x) (sLe(x)) binds to all three selectins, so compounds that mimic sLe(x), such as TBC1269, are potential antagonists. We hypothesized that eosinophils migrate from the basolateral to the apical surface of intestinal epithelium through the orchestrated effects of selectins. TBC1269 was added to fluorescently labeled HL-60 clone 15 eosinophils as well as human blood eosinophils, in incremental amounts. Subsequently, blocking antibodies toward L-selectin and PSGL-1 were used in a similar manner. HL-60 eosinophils were allowed to migrate into T-84 monolayers. The number of migrated HL-60 cells was calculated by comparing fluorescence with known cell densities. HL-60 and human eosinophils that were undergoing migration were significantly lower in the presence of TBC1269. This effect was concentration dependent, and near complete inhibition of migration was seen at a TBC1269 concentration of 10 mg/mL. In addition, HL-60 eosinophil migration was significantly lower in the presence of the blocking antibodies to PSGL-1 and L-selectin (39.2 and 51.6% inhibition, respectively). Simultaneous blocking of PSGL-1 and L-selectin resulted in inhibition of 76.0% of the migration. The results of this study suggest a major role for selectins in the intestinal epithelial migration of differentiated eosinophils. sLe(x), L-selectin, and the P-selectin counterligand PSGL-1 can be potential therapeutic targets.

Neutrophil differentiated HL-60 cells model Mac-1 (CD11b/CD18)-independent neutrophil transepithelial migration

During active intestinal inflammation granulocytes accumulate in the lumen of the gut where they damage the epithelium through the release of various products such as reactive oxygen species and proteolytic enzymes. Previously, using function blocking monoclonal antibodies, we showed that neutrophil migration across intestinal epithelial monolayers in response to various chemoattractants was partially beta(2) integrin Mac-1 (CD11b/CD18)-independent. Here, we show that treating neutrophils with intact monoclonal antibody (mAb) to CD18 activates the cells to express more CD11b. Thus our goal now was to determine whether neutrophil Mac-1-independent transepithelial migration proceeds independently of prior cell activation through Mac-1. We took two approaches, one using blocking Fab' fragments of mAb to CD18 and the second was to develop a neutrophil differentiated HL-60 cell line which is Mac-1 deficient to further study neutrophil/epithelial cell interaction. Anti-CD18 Fab' minimally activated neutrophils but inhibited approximately 75% of transepithelial migration to fMLP while having a minimal effect (</=25% inhibition) on the migration to C5a. Upon incubation with dimethylsulphoxide, HL-60 cells differentiated and up-regulated CD11b expression and migrated to C5a and n-formyl methionyl leucyl phenylalanine in a similar manner to peripheral blood neutrophils. In contrast, CD11b expression was minimal on HL-60 cells differentiated with dibutytyl cAMP to a neutrophil-like phenotype. These cells, however, readily migrated across both intestinal and lung epithelial monolayers in response to C5a. We conclude that Mac-1-independent transepithelial migration does not require prior activation of cells via Mac-1 ligation because HL-60 cells lacking Mac-1 (CD11b/CD18) expression migrate effectively. HL-60 cells differentiated with dbcAMP should greatly assist in the search for the Mac-1-independent ligands for neutrophil migration across epithelium.

The pathobiology of eosinophilic gastroenteritis of childhood: is it really the eosinophil, allergic mediated, or something else?

Over the past decade clinicians have witnessed a dramatic rise in the prevalence of eosinophilic gastrointestinal diseases. Diverse symptoms, a broad range of endoscopic findings, and varying histopathologic features pose several questions: Do eosinophils represent an allergic response? What mechanisms drive eosinophils to specific mucosal targets? How do eosinophils affect the gastrointestinal tissues? Recent clinical and basic studies are investigating the pathogenesis of eosinophilic gastrointestinal diseases. This review highlights the literature concerning the mechanisms that govern these diseases, with a specific focus on diseases of gastrointestinal columnar epithelia (eosinophilic gastroenteritis and eosinophilic colitis). The roles of specific chemokines, such as eotaxin, and the data supporting the involvement of eosinophil granule proteins in disease states, are discussed.