Highlights d Gut-to-brain propagation of pathologic a-synuclein via the vagus nerve causes PD d Dopamine neurons degenerate in the pathologic a-synuclein gut-to-brain model of PD d Gut injection of pathologic a-synuclein causes PD-like motor and non-motor symptoms d PD-like pathology and symptoms require endogenous a-synuclein

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Background-Cellular changes associated with diabetic and idiopathic gastroparesis are not well described.Aim-Describe histologic abnormalities in gastroparesis and compare findings in idiopathic versus diabetic gastroparesis.Methods-Full thickness gastric body biopsies were obtained from 40 gastroparetics (20 diabetic) and matched controls. Sections were stained for H&E and trichrome, and immunolabeled with antibodies against PGP 9.5, nNOS, VIP, substance P and tyrosine hydroxylase to quantify nerves, S100β for glia, Kit for interstitial cells of Cajal (ICC), CD45 and CD68, for immune cells and smoothelin for smooth muscle cells. Tissue was also examined by transmission electron microscopy (TEM).Results-Histological abnormalities were found in 83% of patients. Most common defects were loss of ICC with remaining ICC showing injury, an abnormal immune infiltrate containing macrophages, and decreased nerve fibers. On light microscopy, no significant differences were found between diabetic and idiopathic gastroparesis with the exception of nNOS expression which was decreased in more idiopathic gastroparetics (40%) compared to diabetic (20%) patients by visual grading. On electron microscopy, a markedly increased connective tissue stroma was present in both disorders.Conclusion-This study suggests that on full thickness biopsies, cellular abnormalities are found in the majority of patients with gastroparesis. Most common findings were loss of Kit expression suggesting loss of ICC and an increase in CD45 and CD68 immunoreactivity. These findings suggest that examination of tissue can lead to valuable insights into the pathophysiology of these disorders and offers hope that new therapeutic targets can be found.

1 The effectiveness of antimuscarinic agents in the treatment of the overactive bladder (OAB) syndrome is thought to arise through blockade of bladder muscarinic receptors located on detrusor smooth muscle cells, as well as on nondetrusor structures. 2 Muscarinic M 3 receptors are primarily responsible for detrusor contraction. Limited evidence exists to suggest that M 2 receptors may have a role in mediating indirect contractions and/or inhibition of detrusor relaxation. In addition, there is evidence that muscarinic receptors located in the urothelium/suburothelium and on afferent nerves may contribute to the pathophysiology of OAB. Blockade of these receptors may also contribute to the clinical efficacy of antimuscarinic agents. 3 Although the role of muscarinic receptors in the bladder, other than M 3 receptors, remains unclear, their role in other body systems is becoming increasingly well established, with emerging evidence supporting a wide range of diverse functions. Blockade of these functions by muscarinic receptor antagonists can lead to similarly diverse adverse effects associated with antimuscarinic treatment, with the range of effects observed varying according to the different receptor subtypes affected. 4 This review explores the evolving understanding of muscarinic receptor functions throughout the body, with particular focus on the bladder, gastrointestinal tract, eye, heart, brain and salivary glands, and the implications for drugs used to treat OAB. The key factors that might determine the ideal antimuscarinic drug for treatment of OAB are also discussed. Further research is needed to show whether the M 3 selective receptor antagonists have any advantage over less selective drugs, in leading to fewer adverse events.

Inflammatory Bowel Disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract for which there are few safe and effective therapeutic options for long-term treatment and disease maintenance. In this study, we applied a computational approach to discover novel drug therapies for IBD in silico using publicly available molecular data measuring gene expression in IBD samples and 164 small-molecule drug compounds. Among the top compounds predicted to be therapeutic for IBD by our approach were prednisolone, a corticosteroid known to treat IBD, and topiramate, an anticonvulsant drug not previously described to demonstrate efficacy for IBD or any related disorders of inflammation or the gastrointestinal tract. We experimentally validated our topiramate prediction in vivo using a trinitrobenzenesulfonic acid (TNBS) induced rodent model of IBD. The experimental results demonstrate that oral administration of topiramate is able to significantly reduce gross pathological signs and microscopic damage in primary affected colon tissue in a TNBS-induced rodent model of IBD. These finding suggest that topiramate might serve as a novel therapeutic option for IBD in humans, and support the use of public molecular data and computational approaches to discover novel therapeutic options for IBD.

Populations of interstitial cells of Cajal (ICC) are altered in several gastrointestinal neuromuscular disorders. ICC are identified typically by ultrastructure and expression of Kit (CD117), a protein that is also expressed on mast cells. No other molecular marker currently exists to independently identify ICC. The expression of ANO1 (DOG1, TMEM16A), a Ca(2+)-activated Cl(-) channel, in gastrointestinal stromal tumors suggests it may be useful as an ICC marker. The aims of this study were therefore to determine the distribution of Ano1 immunoreactivity compared with Kit and to establish whether Ano1 is a reliable marker for human and mouse ICC. Expression of Ano1 in human and mouse stomach, small intestine, and colon was investigated by immunofluorescence labeling using antibodies to Ano1 alone and in combination with antibodies to Kit. Colocalization of immunoreactivity was demonstrated by epifluorescence and confocal microscopy. In the muscularis propria, Ano1 immunoreactivity was restricted to cells with the morphology and distribution of ICC. All Ano1-positive cells in the muscularis propria were also Kit positive. Kit-expressing mast cells were not Ano1 positive. Some non-ICC in the mucosa and submucosa of human tissues were Ano1 positive but Kit negative. A few (3.2%) Ano1-positive cells in the human gastric muscularis propria were labeled weakly for Kit. Ano1 labels all classes of ICC and represents a highly specific marker for studying the distribution of ICC in mouse and human tissues with an advantage over Kit since it does not label mast cells.

Background & Aims Diet has major effects on the intestinal microbiota, but the exact mechanisms that alter complex microbial communities have been difficult to elucidate. In addition to the direct influence that diet exerts on microbes, changes in microbiota composition and function can alter host functions such as gastrointestinal (GI) transit time, which in turn can further affect the microbiota. Methods We investigated the relationships among diet, GI motility, and the intestinal microbiota using mice that are germ-free (GF) or humanized (ex-GF mice colonized with human fecal microbiota). Results Analysis of gut motility revealed that humanized mice fed a standard polysaccharide-rich diet had faster GI transit and increased colonic contractility compared with GF mice. Humanized mice with faster transit due to administration of polyethylene glycol or a nonfermentable cellulose-based diet had similar changes in gut microbiota composition, indicating that diet can modify GI transit, which then affects the composition of the microbial community. However, altered transit in mice fed a diet of fermentable fructooligosaccharide indicates that diet can change gut microbial function, which can affect GI transit. Conclusions Based on studies in humanized mice, diet can affect GI transit through microbiota-dependent or microbiota-independent pathways, depending on the type of dietary change. The effect of the microbiota on transit largely depends on the amount and type (fermentable vs non-fermentable) of polysaccharides present in the diet. These results have implications for disorders that affect GI transit and gut microbial communities, including irritable bowel syndrome and inflammatory bowel disease.

Background & Aims As in other tumor types, progression of pancreatic cancer may require a functionally unique population of cancer stem cells. Although such cells have been identified in many invasive cancers, is not clear whether they emerge during early or late stages of tumorigenesis. Using mouse models and human pancreatic cancer cell lines, we investigated whether pre-invasive pancreatic neoplasia contains a subpopulation of cells with distinct morphologies and cancer stem cell-like properties. Methods Pancreatic tissue samples were collected from the KCPdx1, KPCPdx1, and KCiMist1 mouse models of pancreatic intraepithelial neoplasia (PanIN) and analyzed by confocal and electron microscopy, lineage tracing, and fluorescence-activated cell sorting. Subpopulations of human PDAC cells were similarly analyzed and also used in cDNA microarray analyses. Results The microtubule regulator DCLK1 marked a morphologically distinct and functionally unique population of pancreatic cancer-initiating cells. These cells displayed morphologic and molecular features of gastrointestinal tuft cells. Cells that expressed DCLK1 also expressed high levels of ATAT1, HES1, HEY1, IGF1R, and ABL1, and manipulation of these pathways in PDAC cell lines inhibited their clonogenic potential. Pharmacologic inhibition of γ–secretase activity reduced the abundance of these cells in murine PanIN, in a manner that correlated with inhibition of PanIN progression. Conclusions Human PDAC cells and pancreatic neoplasms in mice contain morphologically and functionally distinct subpopulations that have cancer stem cell-like properties. These populations can be identified at the earliest stages of pancreatic tumorigenesis, and provide new cellular and molecular targets for pancreatic cancer treatment and/or chemoprevention.