Meningeal B Cell Clusters Correlate with Submeningeal Pathology in a Natural Model of Multiple Sclerosis.

Multiple sclerosis (MS) is an idiopathic demyelinating disease in which meningeal inflammation correlates with accelerated disease progression. The study of meningeal inflammation in MS has been limited because of constrained access to MS brain/spinal cord specimens and the lack of experimental models recapitulating progressive MS. Unlike induced models, a spontaneously occurring model would offer a unique opportunity to understand MS immunopathogenesis and provide a compelling framework for translational research. We propose granulomatous meningoencephalomyelitis (GME) as a natural model to study neuropathological aspects of MS. GME is an idiopathic, progressive neuroinflammatory disease of young dogs with a female bias. In the GME cases examined in this study, the meninges displayed focal and disseminated leptomeningeal enhancement on magnetic resonance imaging, which correlated with heavy leptomeningeal lymphocytic infiltration. These leptomeningeal infiltrates resembled tertiary lymphoid organs containing large B cell clusters that included few proliferating Ki67+ cells, plasma cells, follicular dendritic/reticular cells, and germinal center B cell-like cells. These B cell collections were confined in a specialized network of collagen fibers associated with the expression of the lympho-organogenic chemokines CXCL13 and CCL21. Although neuroparenchymal perivascular infiltrates contained B cells, they lacked the immune signature of aggregates in the meningeal compartment. Finally, meningeal B cell accumulation correlated significantly with cortical demyelination reflecting neuropathological similarities to MS. Hence, during chronic neuroinflammation, the meningeal microenvironment sustains B cell accumulation that is accompanied by underlying neuroparenchymal injury, indicating GME as a novel, naturally occurring model to study compartmentalized neuroinflammation and the associated pathology thought to contribute to progressive MS.

Krabbe disease successfully treated via monotherapy of intrathecal gene therapy.

Globoid cell leukodystrophy (GLD; Krabbe disease) is a progressive, incurable neurodegenerative disease caused by deficient activity of the hydrolytic enzyme galactosylceramidase (GALC). The ensuing cytotoxic accumulation of psychosine results in diffuse central and peripheral nervous system (CNS, PNS) demyelination. Presymptomatic hematopoietic stem cell transplantation (HSCT) is the only treatment for infantile-onset GLD; however, clinical outcomes of HSCT recipients often remain poor, and procedure-related morbidity is high. There are no effective therapies for symptomatic patients. Herein, we demonstrate in the naturally occurring canine model of GLD that presymptomatic monotherapy with intrathecal AAV9 encoding canine GALC administered into the cisterna magna increased GALC enzyme activity, normalized psychosine concentration, improved myelination, and attenuated inflammation in both the CNS and PNS. Moreover, AAV-mediated therapy successfully prevented clinical neurological dysfunction, allowing treated dogs to live beyond 2.5 years of age, more than 7 times longer than untreated dogs. Furthermore, we found that a 5-fold lower dose resulted in an attenuated form of disease, indicating that sufficient dosing is critical. Finally, postsymptomatic therapy with high-dose AAV9 also significantly extended lifespan, signifying a treatment option for patients for whom HSCT is not applicable. If translatable to patients, these findings would improve the outcomes of patients treated either pre- or postsymptomatically.

AAVrh10 Gene Therapy Ameliorates Central and Peripheral Nervous System Disease in Canine Globoid Cell Leukodystrophy (Krabbe Disease).

Globoid cell leukodystrophy (GLD), or Krabbe disease, is an inherited, neurologic disorder that results from deficiency of a lysosomal enzyme, galactosylceramidase. Most commonly, deficits of galactosylceramidase result in widespread central and peripheral nervous system demyelination and death in affected infants typically by 2 years of age. Hematopoietic stem-cell transplantation is the current standard of care in children diagnosed prior to symptom onset. However, disease correction is incomplete. Herein, the first adeno-associated virus (AAV) gene therapy experiments are presented in a naturally occurring canine model of GLD that closely recapitulates the clinical disease progression, neuropathological alterations, and biochemical abnormalities observed in human patients. Adapted from studies in twitcher mice, GLD dogs were treated by combination intravenous and intracerebroventricular injections of AAVrh10 to target both the peripheral and central nervous systems. Combination of intravenous and intracerebroventricular AAV gene therapy had a clear dose response and resulted in delayed onset of clinical signs, extended life-span, correction of biochemical defects, and attenuation of neuropathology. For the first time, therapeutic effect has been established in the canine model of GLD by targeting both peripheral and central nervous system impairments with potential clinical implications for GLD patients.

LC3 Immunostaining in the Inferior Olivary Nuclei of Cats With Niemann-Pick Disease Type C1 Is Associated With Patterned Purkinje Cell Loss.

The feline model of Niemann-Pick disease, type C1 (NPC1) recapitulates the clinical, neuropathological, and biochemical abnormalities present in children with NPC1. The hallmarks of disease are the lysosomal storage of unesterified cholesterol and multiple sphingolipids in neurons, and the spatial and temporal distribution of Purkinje cell death. In feline NPC1 brain, microtubule-associated protein 1 light chain 3 (LC3) accumulations, indicating autophagosomes, were found within axons and presynaptic terminals. High densities of accumulated LC3 were seen in subdivisions of the inferior olive, which project to cerebellar regions that show the most Purkinje cell loss, suggesting that autophagic abnormalities in specific climbing fibers may contribute to the spatial pattern of Purkinje cell loss seen. Biweekly intrathecal administration of 2-hydroxypropyl-beta cyclodextrin (HPßCD) ameliorated neurological dysfunction, reduced cholesterol and sphingolipid accumulation, and increased lifespan in NPC1 cats. LC3 pathology was reduced in treated animals suggesting that HPßCD administration also ameliorates autophagic abnormalities. This study is the first to (i) identify specific brain regions exhibiting autophagic abnormalities in any species with NPC1, (ii) provide evidence of differential vulnerability among discrete brain nuclei and pathways, and (iii) show the amelioration of these abnormalities in NPC1 cats treated with HPßCD.

Clinical, electrophysiological, and biochemical markers of peripheral and central nervous system disease in canine globoid cell leukodystrophy (Krabbe's disease).

Globoid cell leukodystrophy (GLD), or Krabbe's disease, is a debilitating and always fatal pediatric neurodegenerative disease caused by a mutation in the gene encoding the hydrolytic enzyme galactosylceramidase (GALC). In the absence of GALC, progressive loss of myelin and accumulation of a neurotoxic substrate lead to incapacitating loss of motor and cognitive function and death, typically by 2 years of age. Currently, there is no cure. Recent convincing evidence of the therapeutic potential of combining gene and cell therapies in the murine model of GLD has accelerated the requirement for validated markers of disease to evaluate therapeutic efficacy. Here we demonstrate clinically relevant and quantifiable measures of central (CNS) and peripheral (PNS) nervous system disease progression in the naturally occurring canine model of GLD. As measured by brainstem auditory-evoked response testing, GLD dogs demonstrated a significant increase in I-V interpeak latency and hearing threshold at all time points. Motor nerve conduction velocities (NCVs) in GLD dogs were significantly lower than normal by 12-16 weeks of age, and sensory NCV was significantly lower than normal by 8-12 weeks of age, serving as a sensitive indicator of peripheral nerve dysfunction. Post-mortem histological evaluations confirmed neuroimaging and electrodiagnostic assessments and detailed loss of myelin and accumulation of storage product in the CNS and the PNS. Additionally, cerebrospinal fluid psychosine concentrations were significantly elevated in GLD dogs, demonstrating potential as a biochemical marker of disease. These data demonstrate that CNS and PNS disease progression can be quantified over time in the canine model of GLD with tools identical to those used to assess human patients. © 2016 Wiley Periodicals, Inc.

Intracisternal cyclodextrin prevents cerebellar dysfunction and Purkinje cell death in feline Niemann-Pick type C1 disease.

Niemann-Pick type C1 (NPC) disease is a lysosomal storage disease caused by mutations in the NPC1 gene, leading to an increase in unesterified cholesterol and several sphingolipids, and resulting in hepatic disease and progressive neurological disease. We show that subcutaneous administration of the pharmaceutical excipient 2-hydroxypropyl-ß-cyclodextrin (HPßCD) to cats with NPC disease ameliorated hepatic disease, but doses sufficient to reduce neurological disease resulted in pulmonary toxicity. However, direct administration of HPßCD into the cisterna magna of presymptomatic cats with NPC disease prevented the onset of cerebellar dysfunction for greater than a year and resulted in a reduction in Purkinje cell loss and near-normal concentrations of cholesterol and sphingolipids. Moreover, administration of intracisternal HPßCD to NPC cats with ongoing cerebellar dysfunction slowed disease progression, increased survival time, and decreased the accumulation of brain gangliosides. An increase in hearing threshold was identified as a potential adverse effect. These studies in a feline animal model have provided critical data on efficacy and safety of drug administration directly into the central nervous system that will be important for advancing HPßCD into clinical trials.

Type III collagen modulates fracture callus bone formation and early remodeling.

Type III collagen (Col3) has been proposed to play a key role in tissue repair based upon its temporospatial expression during the healing process of many tissues, including bone. Given our previous finding that Col3 regulates the quality of cutaneous repair, as well as our recent data supporting its role in regulating osteoblast differentiation and trabecular bone quantity, we hypothesized that mice with diminished Col3 expression would exhibit altered long-bone fracture healing. To determine the role of Col3 in bone repair, young adult wild-type (Col3+/+) and haploinsufficent (Col3+/-) mice underwent bilateral tibial fractures. Healing was assessed 7, 14, 21, and 28 days following fracture utilizing microcomputed tomography (microCT), immunohistochemistry, and histomorphometry. MicroCT analysis revealed a small but significant increase in bone volume fraction in Col3+/- mice at day 21. However, histological analysis revealed that Col3+/- mice have less bone within the callus at days 21 and 28, which is consistent with the established role for Col3 in osteogenesis. Finally, a reduction in fracture callus osteoclastic activity in Col3+/- mice suggests Col3 also modulates callus remodeling. Although Col3 haploinsufficiency affected biological aspects of bone repair, it did not affect the regain of mechanical function in the young mice that were evaluated in this study. These findings provide evidence for a modulatory role for Col3 in fracture repair and support further investigations into its role in impaired bone healing.

Neurogenesis in the lamprey central nervous system following spinal cord transection.

After spinal cord transection, lampreys recover functionally and axons regenerate. It is not known whether this is accompanied by neurogenesis. Previous studies suggested a baseline level of nonneuronal cell proliferation in the spinal cord and rhombencephalon (where most supraspinal projecting neurons are located). To determine whether cell proliferation increases after injury and whether this includes neurogenesis, larval lampreys were spinally transected and injected with 5-bromo-2&prime-deoxyuridine (BrdU) at 0-3 weeks posttransection. Labeled cells were counted in the lesion site, within 0.5 mm rostral and caudal to the lesion, and in the rhombencephalon. One group of animals was processed in the winter and a second group was processed in the summer. The number of labeled cells was greater in winter than in summer. The lesion site had the most BrdU labeling at all times, correlating with an increase in the number of cells. In the adjacent spinal cord, the percentage of BrdU labeling was higher in the ependymal than in nonependymal regions. This was also true in the rhombencephalon but only in summer. In winter, BrdU labeling was seen primarily in the subventricular and peripheral zones. Some BrdU-labeled cells were also double labeled by antibodies to glial-specific (antikeratin) as well as neuron-specific (anti-Hu) antigens, indicating that both gliogenesis and neurogenesis occurred after spinal cord transection. However, the new neurons were restricted to the ependymal zone, were never labeled by antineurofilament antibodies, and never migrated away from the ependyma even at 5 weeks after BrdU injection. They would appear to be cerebrospinal fluid-contacting neurons.

Alternatively activated macrophage-derived RELM-{alpha} is a negative regulator of type 2 inflammation in the lung.

Differentiation and recruitment of alternatively activated macrophages (AAMacs) are hallmarks of several inflammatory conditions associated with infection, allergy, diabetes, and cancer. AAMacs are defined by the expression of Arginase 1, chitinase-like molecules, and resistin-like molecule (RELM) alpha/FIZZ1; however, the influence of these molecules on the development, progression, or resolution of inflammatory diseases is unknown. We describe the generation of RELM-alpha-deficient (Retnla(-/-)) mice and use a model of T helper type 2 (Th2) cytokine-dependent lung inflammation to identify an immunoregulatory role for RELM-alpha. After challenge with Schistosoma mansoni (Sm) eggs, Retnla(-/-) mice developed exacerbated lung inflammation compared with their wild-type counterparts, characterized by excessive pulmonary vascularization, increased size of egg-induced granulomas, and elevated fibrosis. Associated with increased disease severity, Sm egg-challenged Retnla(-/-) mice exhibited elevated expression of pathogen-specific CD4(+) T cell-derived Th2 cytokines. Consistent with immunoregulatory properties, recombinant RELM-alpha could bind to macrophages and effector CD4(+) Th2 cells and inhibited Th2 cytokine production in a Bruton's tyrosine kinase-dependent manner. Additionally, Retnla(-/-) AAMacs promoted exaggerated antigen-specific Th2 cell differentiation. Collectively, these data identify a previously unrecognized role for AAMac-derived RELM-alpha in limiting the pathogenesis of Th2 cytokine-mediated pulmonary inflammation, in part through the regulation of CD4(+) T cell responses.

Evidence for the epithelial to mesenchymal transition in biliary atresia fibrosis.

The epithelial to mesenchymal transition has recently been implicated as a source of fibrogenic myofibroblasts in organ fibrosis, particularly in the kidney. There is as yet minimal evidence for the epithelial to mesenchymal transition in the liver. We hypothesized that this process in biliary epithelial cells plays an important role in biliary fibrosis and might be found in patients with especially rapid forms, such as is seen in biliary atresia. We therefore obtained liver tissue from patients with biliary atresia as well as a variety of other pediatric and adult liver diseases. Tissues were immunostained with antibodies against the biliary epithelial cell marker CK19 as well as with antibodies against proteins characteristically expressed by cells undergoing the epithelial to mesenchymal transition, including fibroblast-specific protein 1, the collagen chaperone heat shock protein 47, the intermediate filament protein vimentin, and the transcription factor Snail. The degree of colocalization was quantified using a multispectral imaging system. We observed significant colocalization between CK19 and other markers of the epithelial to mesenchymal transition in biliary atresia as well as other liver diseases associated with significant bile ductular proliferation, including primary biliary cirrhosis. There was minimal colocalization seen in healthy adult and pediatric livers, or in livers not also demonstrating bile ductular proliferation. Multispectral imaging confirmed significant colocalization of the different markers in biliary atresia. In conclusion, we present significant histologic evidence suggesting that the epithelial to mesenchymal transition occurs in human liver fibrosis, particularly in diseases such as biliary atresia and primary biliary cirrhosis with prominent bile ductular proliferation.

RELMbeta/FIZZ2 is a goblet cell-specific immune-effector molecule in the gastrointestinal tract.

Gastrointestinal (GI) nematode infections are an important public health and economic concern. Experimental studies have shown that resistance to infection requires CD4(+) T helper type 2 (Th2) cytokine responses characterized by the production of IL-4 and IL-13. However, despite >30 years of research, it is unclear how the immune system mediates the expulsion of worms from the GI tract. Here, we demonstrate that a recently described intestinal goblet cell-specific protein, RELMbeta/FIZZ2, is induced after exposure to three phylogenetically distinct GI nematode pathogens. Maximal expression of RELMbeta was coincident with the production of Th2 cytokines and host protective immunity, whereas production of the Th1 cytokine, IFN-gamma, inhibited RELMbeta expression and led to chronic infection. Furthermore, whereas induction of RELMbeta was equivalent in nematode-infected wild-type and IL-4-deficient mice, IL-4 receptor-deficient mice showed minimal RELMbeta induction and developed persistent infections, demonstrating a direct role for IL-13 in optimal expression of RELMbeta. Finally, we show that RELMbeta binds to components of the nematode chemosensory apparatus and inhibits chemotaxic function of a parasitic nematode in vitro. Together, these results suggest that intestinal goblet cell-derived RELMbeta may be a novel Th2 cytokine-induced immune-effector molecule in resistance to GI nematode infection.

Complex regulation of the lactase-phlorizin hydrolase promoter by GATA-4.

Lactase-phlorizin hydrolase (LPH), a marker of intestinal differentiation, is expressed in absorptive enterocytes on small intestinal villi in a tightly regulated pattern along the proximal-distal axis. The LPH promoter contains binding sites that mediate activation by members of the GATA-4, -5, and -6 subfamily, but little is known about their individual contribution to LPH regulation in vivo. Here, we show that GATA-4 is the principal GATA factor from adult mouse intestinal epithelial cells that binds to the mouse LPH promoter, and its expression is highly correlated with that of LPH mRNA in jejunum and ileum. GATA-4 cooperates with hepatocyte nuclear factor (HNF)-1alpha to synergistically activate the LPH promoter by a mechanism identical to that previously characterized for GATA-5/HNF-1alpha, requiring physical association between GATA-4 and HNF-1alpha and intact HNF-1 binding sites on the LPH promoter. GATA-4 also activates the LPH promoter independently of HNF-1alpha, in contrast to GATA-5, which is unable to activate the LPH promoter in the absence of HNF-1alpha. GATA-4-specific activation requires intact GATA binding sites on the LPH promoter and was mapped by domain-swapping experiments to the zinc finger and basic regions. However, the difference in the capacity between GATA-4 and GATA-5 to activate the LPH promoter was not due to a difference in affinity for binding to GATA binding sites on the LPH promoter. These data indicate that GATA-4 is a key regulator of LPH gene expression that may function through an evolutionarily conserved mechanism involving cooperativity with an HNF-1alpha and/or a GATA-specific pathway independent of HNF-1alpha.

Homozygous loss of menin is well tolerated in liver, a tissue not affected in MEN1.

Most tumor suppressor genes show a widespread pattern of expression, yet individuals with germline, heterozygous loss of function of such genes develop tumors in a restricted set of tissues. This paradox has generated a multitude of speculative hypotheses. The gene for multiple endocrine neoplasia type I (MEN1) encodes a ubiquitously expressed tumor suppressor of unknown function called menin. Humans and mice with germline, heterozygous loss-of-function mutations in the MEN1 gene almost always develop at least one endocrine tumor by late adulthood, and examination of those tumors invariably reveals loss of the wild-type allele. To investigate the paradox of tissue-specific tumor phenotype in MEN1, mice homozygous for an Men1 gene with exons 3-8 flanked by loxP sites were bred to transgenic mice expressing cre from the albumin promoter. This strategy allowed us to generate mice with homozygous deletion of the Men1 gene in liver, a tissue not normally predisposed to developing tumors in humans or mice with heterozygous MEN1 loss-of-function mutations. Livers that were completely null for menin expression appeared entirely normal and remained tumor free until late adulthood. These results argue against certain hypotheses previously proposed for the tissue specificity of tumor suppressor genes and provide insights to the mechanism of tissue specificity in MEN1.

Cell proliferation in the lamprey central nervous system.

After spinal cord transection, axons regenerate both in larval and adult lampreys. It is not known to what degree cells proliferate, even in the uninjured animal. Therefore, we have determined the prevalence of mitosis in the lamprey central nervous system (CNS). Bromodeoxyuridine (BrdU) was injected and incorporated for 4 hours into 2- to 5-year-old larvae, animals undergoing metamorphosis, and young adults. Labeled cells were counted in the rhombencephalon (where most supraspinal projecting neurons are located) and spinal cord. A mitotic index (MI) was calculated as the percentage of nuclei that were labeled. There was a seasonal variation in mitotic activity, with higher MIs occurring in summer. Within the summer, there was an additional transient spike in mitosis, especially in the rhombencephalon. There was no correlation between age and MI within the range of developmental stages examined. Baseline MIs in the rhombencephalon and spinal cord were approximately 0.15% and 0.20%, respectively. In most animals, the highest mitotic rates in both the rhombencephalon and spinal cord were seen in the ependyma, but many labeled cells were found in nonependymal regions as well. During the summer spike, almost all of the additional mitosis in the rhombencephalon was in the ependyma, but this finding was not true in the spinal cord. Many BrdU-labeled cells in the spinal cord and rhombencephalon were also stained by monoclonal antibodies specific for lamprey glial keratin but were never labeled by anti-neurofilament antibodies. These results suggest that (1) neurogenesis is uncommon in the lamprey CNS; (2) during most of the year, baseline gliogenesis occurs mainly in the ependyma with substantial contribution by nonependymal areas. During the summer, a spike of mitotic activity occurs in the ependyma of the rhombencephalon and throughout the spinal cord.

Of mice and MEN1: Insulinomas in a conditional mouse knockout.

Patients with multiple endocrine neoplasia type 1 (MEN1) develop multiple endocrine tumors, primarily affecting the parathyroid, pituitary, and endocrine pancreas, due to the inactivation of the MEN1 gene. A conditional mouse model was developed to evaluate the loss of the mouse homolog, Men1, in the pancreatic beta cell. Men1 in these mice contains exons 3 to 8 flanked by loxP sites, such that, when the mice are crossed to transgenic mice expressing cre from the rat insulin promoter (RIP-cre), exons 3 to 8 are deleted in beta cells. By 60 weeks of age, >80% of mice homozygous for the floxed Men1 gene and expressing RIP-cre develop multiple pancreatic islet adenomas. The formation of adenomas results in elevated serum insulin levels and decreased blood glucose levels. The delay in tumor appearance, even with early loss of both copies of Men1, implies that additional somatic events are required for adenoma formation in beta cells. Comparative genomic hybridization of beta cell tumor DNA from these mice reveals duplication of chromosome 11, potentially revealing regions of interest with respect to tumorigenesis.

A novel colonic repressor element regulates intestinal gene expression by interacting with Cux/CDP.

Intestinal gene regulation involves mechanisms that direct temporal expression along the vertical and horizontal axes of the alimentary tract. Sucrase-isomaltase (SI), the product of an enterocyte-specific gene, exhibits a complex pattern of expression. Generation of transgenic mice with a mutated SI transgene showed involvement of an overlapping CDP (CCAAT displacement protein)-GATA element in colonic repression of SI throughout postnatal intestinal development. We define this element as CRESIP (colon-repressive element of the SI promoter). Cux/CDP interacts with SI and represses SI promoter activity in a CRESIP-dependent manner. Cux/CDP homozygous mutant mice displayed increased expression of SI mRNA during early postnatal development. Our results demonstrate that an intestinal gene can be repressed in the distal gut and identify Cux/CDP as a regulator of this repression during development.

Hepatocyte nuclear factor-1 alpha, GATA-4, and caudal related homeodomain protein Cdx2 interact functionally to modulate intestinal gene transcription. Implication for the developmental regulation of the sucrase-isomaltase gene.

Sucrase-isomaltase (SI), an intestine-specific gene, is induced in the differentiated small intestinal villous epithelium during the suckling-weaning transition in mice. We have previously identified cis-acting elements within a short evolutionarily conserved SI promoter. However, the nature and profile of expression of the interacting proteins have not been fully characterized during this developmental transition. Herein, we show that hepatocyte nuclear factor-1 alpha (HNF-1 alpha), GATA-4, and caudal related homeodomain proteins Cdx2 and Cdx1 are the primary transcription factors from the adult mouse intestinal epithelium to interact with the SIF3, GATA, and SIF1 elements of the SI promoter. We wanted to study whether HNF-1 alpha, GATA-4, and Cdx2 can cooperate in the regulation of SI gene expression. Immunolocalization experiments revealed that HNF-1 alpha is detected in rare epithelial cells of suckling mice and becomes progressively more expressed in the villous epithelial cells during the suckling-weaning transition. GATA-4 protein is expressed exclusively in villous differentiated epithelial cells of the proximal small intestine, decreases in expression in the ileum, and becomes undetectable in the colon. HNF-1 alpha, GATA-4, and Cdx2 interact in vitro and in vivo. These factors activate SI promoter activity in cotransfection experiments where GATA-4 requires the presence of both HNF-1 alpha and Cdx2. These findings imply a combinatory role of HNF-1 alpha, Cdx2, and GATA-4 for the time- and position-dependent regulation of SI transcription during development.

Anatomic and functional characteristics of the rat ileal pouch.

BACKGROUND: The definitive operation for chronic ulcerative colitis (UC) and familial adenomatous polyposis is total proctocolectomy with ileal pouch-anal anastomosis (IPAA). Mild inflammation (pouchitis) is omnipresent in pouches and becomes severe in 50% of UC patients with IPAA. The etiology of pouchitis is likely due to combined genetic, microbial, and immunologic factors. Epithelial cell exposure to surgical trauma and/or to changes in intestinal bacterial composition may account for the inflammatory infiltrate. Progress in understanding pouchitis is restricted by the lack of suitable animal models. METHODS: An ileal pouch-rectal anastomosis [IPRA] in rats was developed to reproduce a model of human IPAA and clinical, gross and histologic criteria were determined. RESULTS: Many shared features with human ileal pouch were observed. CONCLUSION: IPRA is an important in vivo model to study mechanisms of repair, defense and immunity that may contribute to pouchitis.

Cdx2 ectopic expression induces gastric intestinal metaplasia in transgenic mice.

BACKGROUND & AIMS: Intestinal-type gastric cancer is often preceded by intestinal metaplasia in humans. The genetic events responsible for the transdifferentiation that occurs in intestinal metaplasia are not well understood. Cdx2, a transcription factor whose expression is normally limited to the intestine, has been detected in gastric intestinal metaplasia. Cdx2 induces differentiation of intestinal epithelial cells in vitro; therefore, we sought to establish whether a causal relationship exists between Cdx2 activation and intestinal metaplasia. METHODS: Cdx2 expression was directed to the gastric mucosa in transgenic mice using cis-regulatory elements of Foxa3 (Hnf3gamma). Transgenic mice were analyzed for histologic and gene expression changes. RESULTS: Histologic examination of the gastric mucosa of the Foxa3/Cdx2 mice revealed the presence of alcian blue-positive intestinal-type goblet cells, a hallmark of intestinal metaplasia. In addition, Cdx2 induced the expression of intestine-specific genes. CONCLUSIONS: Gastric expression of Cdx2 alone was sufficient to induce intestinal metaplasia in mice. These mice represent a powerful tool to investigate the molecular mechanisms that promote intestinal metaplasia. Moreover, as gastric cancer in humans is often preceded by intestinal metaplasia, the phenotype described here strongly suggests involvement of Cdx2 in the initiation of the process leading to intestinal neoplasia of the gastric mucosa.