An autologous colonic organoid-derived monolayer model to study immune: bacterial interactions in Crohn's disease patients.

Objectives: Crohn's disease (CD) initiation and pathogenesis are believed to involve an environmental trigger in a genetically susceptible person that results in an immune response against commensal gut bacteria, leading to a compromised intestinal epithelial barrier and a cycle of inflammation. However, it has been difficult to study the contribution of all factors together in a physiologically relevant model and in a heterogenous patient population.

Methods: We developed an autologous colonic monolayer model that incorporated the immune response from the same donor and a commensal bacteria, .

Intestinal Organoids as a Tool for Inflammatory Bowel Disease Research.

Inflammatory Bowel Diseases (IBD) are difficult to model as freshly acquired tissues are short-lived, provide data as a snapshot in time, and are not always accessible. Many patients with IBD are non-responders to first-line treatments, and responders are prone to developing resistance to treatment over time-resulting in reduced patient quality of life, increased time to remission, and potential relapse. IBD is heterogenous and we are yet to fully understand the mechanisms of disease; thus, our ability to diagnose and prescribe optimal treatment remains ineffective.

The JAK-Inhibitor Tofacitinib Rescues Human Intestinal Epithelial Cells and Colonoids from Cytokine-Induced Barrier Dysfunction.

Background: Alterations to epithelial tight junctions can compromise the ability of the epithelium to act as a barrier between luminal contents and the underlying tissues, thereby increasing intestinal permeability, an early critical event in inflammatory bowel disease (IBD). Tofacitinib (Xeljanz), an orally administered pan-Janus kinase (JAK) inhibitor, was recently approved for the treatment of moderate to severe ulcerative colitis. Nevertheless, the effects of tofacitinib on intestinal epithelial cell functions are largely unknown.

cAMP-dependent secretagogues stimulate the NaHCO cotransporter in the villous epithelium of the brushtail possum, Trichosurus vulpecula.

In the ileum of the brushtail possum, Trichosurus vulpecula, fluid secretion appears to be driven by electrogenic HCO secretion. Consistent with this, the cystic fibrosis transmembrane conductance regulator is expressed in the apical membrane of the ileal epithelial cells and the pancreatic or secretory variant of the NaHCO cotransporter in the basolateral membrane. This suggests that in the possum ileum, electrogenic HCO secretion is driven by basolateral NaHCO cotransporter (NBC) activity.

Distinct immune signatures in the colon of Crohn's disease and ankylosing spondylitis patients in the absence of inflammation.

Crohn's disease (CD) is an inflammatory bowel disease characterized by patchy inflammation of the gastrointestinal tract. Ankylosing spondylitis (AS) is primarily characterized by inflammation of the lower vertebral column, and many patients with AS present with inflammatory gut symptoms. Genome-wide association studies have highlighted significant overlap in short nucleotide polymorphisms for both diseases.

Aggravation of Established Colitis in Specific Pathogen-free IL-10 Knockout Mice by Restraint Stress Is Not Mediated by Increased Colonic Permeability.

Background: Pathogenic mechanisms responsible for the undulating symptom pattern, or indeed causative agents for the development, of inflammatory bowel diseases [IBD] are largely unknown. Many physicians and most patients are convinced that stress affects the course of IBD. As with most factors that contribute to IBD, it is unclear whether stress merely exacerbates established disease or indeed contributes to the development of disease.

Glucose transport into everted sacs of the small intestine of mice.

The Na(+)-glucose cotransporter is a key transport protein that is responsible for absorbing Na(+) and glucose from the luminal contents of the small intestine and reabsorption by the proximal straight tubule of the nephron. Robert K. Crane originally described the cellular model of absorption of Na(+) and glucose by a "cotransport process" in 1960.

Is the north to south gradient in inflammatory bowel disease a global phenomenon?

Inflammatory bowel diseases (IBDs), such as Crohn's disease and ulcerative colitis, are multifactorial diseases that result from an overly aggressive immune response towards an environmental trigger in a genetically susceptible host. Much has been learned about susceptibility genes; however, environmental triggers are still largely unknown. In the 1990s, a large study from Europe suggested a north-south gradient regarding the incidence of IBD; however, this was never shown convincingly for the USA.

CFTR is restricted to a small population of high expresser cells that provide a forskolin-sensitive transepithelial Cl- conductance in the proximal colon of the possum, Trichosurus vulpecula.

The cystic fibrosis transmembrane conductance regulator (CFTR) is central to anion secretion in both the possum and eutherian small intestine. Here, we investigated its role in the possum proximal colon, which has novel transport properties compared with the eutherian proximal colon. Despite considerable CFTR expression, high doses of the CFTR activator forskolin (EC(50)≈10 μmol l(-1)) were required for a modest, CFTR-dependent increase in short-circuit current (I(sc)) in the proximal colon.

Probiotics decreased the bioavailability of the bile acid analog, monoketocholic acid, when coadministered with gliclazide, in healthy but not diabetic rats.

In recent studies we showed that gliclazide has no hypoglycemic effect on type 1 diabetic (T1D) rats while MKC does, and their combination exerted a better hypoglycemic effect than MKC alone. We also showed that the most hypoglycemic effect was noticed when T1D rats were treated with probiotics then gavaged with MKC + gliclazide (blood glucose decreased from 24 ± 3 to 10 ± 2 mmol/l). The aim of this study is to investigate the influence of probiotics on MKC pharmacokinetics when coadministered with gliclazide, in T1D rats.

The distribution and expression of CFTR restricts electrogenic anion secretion to the ileum of the brushtail possum, Trichosurus vulpecula.

In eutherian mammals, fluid secretion is essential for intestinal function. This is driven by electrogenic Cl(-) secretion, which involves a NaK2Cl cotransporter (NKCC1) in the enterocyte basolateral membrane and the cystic fibrosis transmembrane conductance regulator (CFTR) in the apical membrane. However, in the possum ileum, NKCC1 expression is low and secretagogues stimulate electrogenic HCO(3)(-) secretion driven by a basolateral NaHCO(3) cotransporter (pNBCe1).

COMMD1 downregulates the epithelial sodium channel through Nedd4-2.

The epithelial sodium channel (ENaC) is important for the long-term control of Na(+) homeostasis and blood pressure. Our previous studies demonstrated that Copper Metabolism Murr1 Domain-containing protein 1 (COMMD1; previously known as Murr1), a protein involved in copper metabolism, inhibited amiloride-sensitive current in Xenopus laevis oocytes expressing ENaC (J Biol Chem 279: 5429, 2004). In this study, we report that COMMD1 inhibits amiloride-sensitive current in mammalian epithelial cells expressing ENaC, that the COMM domain of COMMD1 is sufficient for this effect, and that knockdown of COMMD1 increases amiloride-sensitive current.

Ricin as a weapon of mass terror--separating fact from fiction.

In recent years there has been an increased concern regarding the potential use of chemical and biological weapons for mass urban terror. In particular, there are concerns that ricin could be employed as such an agent. This has been reinforced by recent high profile cases involving ricin, and its use during the cold war to assassinate a high profile communist dissident.

Secretagogues stimulate electrogenic HCO3- secretion in the ileum of the brushtail possum, Trichosurus vulpecula: evidence for the role of a Na+/HCO3- cotransporter.

Fluid secretion is essential for intestinal function and, in eutherian mammals, is driven by electrogenic Cl(-) transport, which is dependent upon a bumetanide-sensitive, basolateral Na(+)/K(+)/2 Cl(-) cotransporter, NKCC1. However, ileal secretion in the brushtail possum, a marsupial, involves a fundamentally different process, since NKCC1 expression is low in this tissue and the secretagogue-induced short circuit current (I(sc)) is insensitive to bumetanide. In view of these differences we have investigated the basis of the secretory response of the possum ileum.

Electrogenic Cl(-) secretion does not occur in the ileum of the Australian common brushtail possum, Trichosurus vulpecula, due to low levels of expression of the NaK2Cl cotransporter, NKCC1.

The colon of the brushtail possum does not have an electrogenic secretory response. Given the functional significance of electrogenic Cl(-) secretion in the intestine of eutherian mammals, we have investigated the secretory response in the small intestine of this marsupial. In the Ussing chamber cAMP-dependent secretagogues stimulated a sustained increase in ileal short-circuit current (Isc), whereas Ca(2+)-dependent secretagogues induced a transient increase.

Gliclazide reduces MKC intestinal transport in healthy but not diabetic rats.

The aim is to investigate the influence of the antidiabetic drug gliclazide on the ileal permeation of the semisynthetic bile acid, MKC, in tissues from healthy and diabetic rats. Sixteen Wistar rats (350 +/- 50 g) were randomly allocated into four groups (4 rats per group, 8 chambers per rat, i.e.

Influence of the semisynthetic bile acid (MKC) on the ileal permeation of gliclazide in healthy and diabetic rats.

The aim of this study is to investigate how the semisynthetic bile acid; 3alpha,7alpha-dihydroxy-12-keto-5beta-cholanate, also known as 12-monoketocholic acid (MKC) influences the ileal permeation of the antidiabetic drug gliclazide in healthy and diabetic rats. Male Wistar rats were divided into 10 groups (n = 32), of which 5 comprised healthy rats (1 to 5) and 5 diabetic rats (6 to 10). Group 1 was used to measure the permeation of gliclazide (200 microg/ml) alone (control) while in groups 2 to 5 gliclazide permeation was measured in the presence of MKC (50 microg/ml), glibenclamide (100 mug/ml), rifampicin (100 mug/ml) and verapamil (30 microg/ml), respectively, using Ussing chambers.

Probiotic treatment reduces blood glucose levels and increases systemic absorption of gliclazide in diabetic rats.

The action of gliclazide, a sulphonylurea with beneficial extrapancreatic effects in diabetes, may be enhanced by administering probiotics. The aim of this study was to investigate the influence of probiotics on gliclazide pharmacokinetics and the effect of both probiotics and gliclazide on blood glucose levels in healthy and diabetic rats. Male Wistar rats (2 to 3 months, weight 350 +/- 50 g) were randomly allocated to 4 groups (n =10), two of which were treated with alloxan i.

Probiotic Pre-treatment Reduces Gliclazide Permeation (ex vivo) in Healthy Rats but Increases It in Diabetic Rats to the Level Seen in Untreated Healthy Rats.

AIM: To investigate the influence of probiotic pre-treatment on the permeation of the antidiabetic drug gliclazide in healthy and diabetic rats. METHODS: Wistar rats (age 2-3 months, weight 350 +/- 50 g) were randomly allocated into one of 4 groups (N = 16 each group): healthy control, healthy probiotic, diabetic control, and diabetic probiotic. Probiotics (75 mg/kg, equal quantities of Lactobacillus acidophilus, Bifidobacterium lactis, and Lactobacillus rhamnosus) were administered twice a day for three days to the appropriate groups after diabetes had been induced with alloxan i.

Methoxsalen stimulates electrogenic Cl- secretion in the mouse jejunum.

We used the short-circuit current (I(sc)) and patch-clamp techniques to investigate the effects of methoxsalen (MTX) on the electrogenic Cl- secretion of the mouse jejunum. MTX stimulated a sustained increase in Isc that was dose dependent. Bumetanide inhibited MTX-stimulated Isc in a dose-dependent manner consistent with activation of Cl- secretion.

Isocratic liquid chromatographic assay for monitoring the degradation of luteinizing hormone releasing hormone by extracts from the gastrointestinal tract of possums.

A simple HPLC method to separate human luteinizing hormone releasing hormone (LHRH) from its metabolites using an isocratic elution is described. Intact LHRH and five metabolites were separated in 11.4 min.