Therapeutic effects of paeoniflorin on irritable bowel syndrome in rats.

BACKGROUND: Irritable bowel syndrome (IBS) is a functional bowel disorder (FBD). OBJECTIVES: To assess the therapeutic effects of paeoniflorin (PF) on IBS in rats. METHOD: Sixty male Sprague-Dawley rats were randomly divided into normal, model, positive drug, low-dose PF, medium-dose PF and high-dose PF groups (n = 10). After gavage for 2 consecutive weeks, the effect of PF on abdominal pain symptoms was assessed based on the abdominal withdrawal reflex (AWR) score, fecal water content and pathological changes in colon tissues. D-lactate, interleukin-1ß (IL-1ß), transforming growth factor-ß (TGF-ß) and tumor necrosis factor-α (TNF-α) were detected by enzyme-linked immunosorbent assay, and phosphorylated nuclear factor kappa B (p-NF-κB) p65 was detected by Western blotting. The abundance and diversity changes of intestinal flora were explored using 16S ribosomal RNA sequencing. RESULT: In PF groups, the mucosal morphology of colon tissues was intact, and the glands were arranged neatly and structured clearly, without obvious inflammatory cell infiltration. Compared with the model group, PF groups had significantly elevated pain threshold, and mRNA and protein levels of zonula occludens-1 (ZO-1) and occludin, decreased AWR score at 20 mmHg pressure, fecal water content, mRNA levels of IL-1ß, TGF-ß, and TNF-α, protein level of p-NF-κB p65 and level of serum D-lactate, and reduced levels of serum IL-1ß, TGF-ß, and TNF-α (p < 0.05, p < 0.01). PF groups had higher abundance of Lactobacillus, Akkermansia, Alistipes, and Bacteroides, but lower abundance of Desulfovibrio, Parasutterella, and Enterococcus than those of the model group. CONCLUSIONS: PF exerts therapeutic effects on IBS in rats probably by regulating the intestinal flora, and then up-regulating the expressions of ZO-1 and occludin in colon tissue while down-regulating the levels of IL-1ß, TGF-ß, TNF-α, D-lactate and p-NF-κB p65.

Enterocolic increase of cannabinoid receptor type 1 and type 2 and clinical improvement after probiotic administration in dogs with chronic signs of colonic dysmotility without mucosal inflammatory changes.

BACKGROUND: Colonic dysmotility in dogs can cause different GI signs. Sometimes, histology of enterocolic biopsies does not reveal inflammatory infiltrates or mucosal lesions that are typically associated with clinical disease activity. It is speculated that, similarly to humans, colonic dysmotility may be anxiety-based, although recent data demonstrate that irritable bowel syndrome (IBS) could result from acute infectious enteritis. Specific Lactobacillus spp. strains administered orally in humans induced the expression of µ-opioid and cannabinoid receptors in mucosal enterocytes, modulating intestinal morphine-like analgesic functions. We investigated the potential association of GI signs caused by colonic dysmotility and mucosal expression of cannabinoid receptors in intestinal epithelial cells and the number of mucosal mast cells. METHODS: Ten to 15 endoscopic biopsies were collected from colonic mucosa of 20 dogs diagnosed with dysmotility disturbances before and after probiotic (Slab51 bacterial blend; Sivoy® ) administration (3-month period). Number and distribution of mast cells (MCs), and cannabinoid receptor type 1 (CB1) and type 2 (CB2) were evaluated by immunohistochemistry and PCR. Results were compared to data obtained from five clinically healthy dogs (archive samples). KEY RESULTS: Decreased numbers of MCs (P < .0001) and increased CB1- and CB2-positive epithelial cells (P < .0001) in diseased dogs were positively associated with post-treatment CCECAI scores (P < .0001). CONCLUSIONS AND INFERENCES: Our results suggest that probiotic administration can reduce signs of colonic dysmotility, possibly due to microbiota modulation and epithelial cell receptor-mediated signaling in intestinal mucosa.

Relationship of the mucosal microbiota to gastrointestinal inflammation and small cell intestinal lymphoma in cats.

BACKGROUND: The gastrointestinal (GI) microbiota in healthy cats is altered in IBD. Little research has been performed to identify whether specific bacterial groups are associated with small cell GI lymphoma (LSA). HYPOTHESIS: Mucosal bacteria, including Enterobacteriaceae and Fusobacterium spp., are abundant in intestinal biopsies of cats with small cell GI LSA compared to cats with IBD. ANIMALS: Fourteen cats with IBD and 14 cats with small cell GI LSA. METHODS: Retrospective case control study. A search of the medical records was performed to identify cats diagnosed with IBD and with GI LSA. Bacterial groups identified by FISH in GI biopsies were compared between cohorts and correlated to CD11b+ and NF-κB expression. RESULTS: Fusobacterium spp. (median; IQR bacteria/region) were higher in cats with small cell GI LSA in ileal (527; 455.5 - 661.5; P = .046) and colonic (404.5; 328.8 - 455.5; P = .016) adherent mucus, and combined colonic compartments (free mucus, adherent mucus, attaching to epithelium) (8; 0 - 336; P = .017) compared to cats with IBD (ileum: 67; 31.5 - 259; colon: 142.5; 82.3 - 434.5; combined: 3; 0 - 34). Bacteroides spp. were higher in ileal adherent mucus (P = .036) and 3 combined ileal compartments (P = .034) of cats with small cell GI LSA. There were significant correlations between Fusobacterium spp. totals and CD11b+ cell (P = .009; rs .476) and NF-κB expression (P = .004; rs .523). CONCLUSIONS: The bacterial alterations appreciated might be influential in development of small cell GI LSA, and should drive further studies to elucidate the effects of microbial-mediated inflammation on GI cancer progression.

Is irritable bowel syndrome also present in dogs?

Irritable bowel syndrome (IBS) in humans is described as the recurrent presence of gastrointestinal signs, without gross histopathologic evidence of inflammation and of other morphologic lesions; however, it is a syndrome not unanimously defined in veterinary medicine. There is some evidence that dysmotility could be related to stressors in some dogs that present with clinical signs (e.g. chronic idiopathic large-bowel diarrhea) that share overlapping aspects with human IBS. The authors hypothesize that an IBS-like condition, similar to that described in humans, might also be present in dogs. Nevertheless, the diagnostic path for canine IBS needs to be further elucidated and its pathogenesis better defined for a more rational therapeutic approach.

Expression of serotonin, chromogranin-A, serotonin receptor-2B, tryptophan hydroxylase-1, and serotonin reuptake transporter in the intestine of dogs with chronic enteropathy.

Serotonin regulates many intestinal motor and sensory functions. Altered serotonergic metabolism has been described in human gastrointestinal diseases. The objective of our study was to compare expression of several components of the serotonergic system [serotonin (5-HT), serotonin reuptake transporter protein (SERT), tryptophan hydroxylase-1 (TPH-1), 5-HT receptor2B (5-HT2B)] and the enterochromaffin cell marker chromogranin-A (CgA) in the intestinal mucosa between dogs with chronic enteropathy and healthy controls. Serotonin and CgA expression were determined by immunohistochemistry using banked and prospectively obtained, paraffin-embedded canine gastrointestinal biopsies (n = 11), and compared to a control group of canine small intestinal sections (n = 10). Expression of SERT, TPH-1, and 5-HT2B were determined via real-time reverse transcription (qRT)-PCR using prospectively collected endoscopic duodenal biopsies (n = 10) and compared to an additional control group of control duodenal biopsies (n = 8, control group 2) showing no evidence of intestinal inflammation. Dogs with chronic enteropathies showed strong staining for both 5-HT and CgA. Mean positive cells per high power field (HPF) were significantly increased for both compounds in dogs with chronic enteropathies (p < 0.001 for 5-HT; p < 0.05 for CgA). The number of 5-HT-positive and CgA-positive cells/HPF showed significant correlation in the entire group of dogs, including both diseased and healthy individuals (Pearson r(2) = 0.2433, p = 0.016). No significant differences were observed for SERT, TPH-1, or 5-HT2B expression; however, dogs with chronic enteropathy showed greater variability in expression of TPH-1 and 5-HT2B We conclude that components of the neuroendocrine system show altered expression in the intestinal mucosa of dogs with chronic enteropathy. These changes may contribute to nociception and clinical signs in these patients.

Expression of reference genes and T helper 17 associated cytokine genes in the equine intestinal tract.

There is accumulating evidence for the involvement of pro-inflammatory cytokines associated with a T helper 17 response in intestinal disorders such as inflammatory bowel disease (IBD) in humans. The involvement of interleukin (IL)-17 or IL-23 in equine IBD has not been studied and most gene expression studies in the equine intestine have been limited to the use of a single non-validated reference gene. In this study, expression of the reference gene candidates ß2 microglobulin (ß2M), glyceraldehyde 3-phosphate dehydrogenase (GAPDH), histone H2A type 1, hypoxanthine-guanine phosphoribosyltransferase (HPRT), 60S ribosomal protein L32 (RPL32), succinate dehydrogenase complex subunit A (SDHA) and transferrin receptor 1 protein coding (TFRC)in the equine intestine was evaluated by quantitative PCR. Three to four reference genes were adequate for normalisation of gene expression in the healthy duodenum, mid-jejunum, colon and rectum, although each segment required a unique combination of reference genes. No combination of the evaluated genes was optimal for the caecum and ileum. Another combination of reference genes (GAPDH, HPRT, RPL32 and SDHA) was optimal for normalisation of rectal samples from healthy and IBD-affected horses, indicating that reference genes should be re-evaluated if material from diseased specimens is analysed. Basal expression of IL-12p40, IL-17A and IL-23p19 was detected in each segment, which will enable gene expression studies of these cytokines by relative quantification.

Do horses suffer from irritable bowel syndrome?

Irritable bowel syndrome (IBS) in man is not a single entity but has several causes. One of the most common forms has similarities with colic and laminitis in horses. Undigested food residues may pass from the small intestine into the colon where bacterial fermentation produces chemicals that lead to disease. In horses the consequences may be disastrous, but in healthy humans such malabsorption may not be harmful. After events such as bacterial gastroenteritis or antibiotic treatment, an imbalance of the colonic microflora with overgrowth of facultative anaerobes may arise, leading to malfermentation and IBS. It is not known whether such subtle changes may likewise be present in the microflora of horses who are susceptible to colic and laminitis. Metabolomic studies of urine and faeces may provide a suitable way forward to identify such changes in the horse's gut and thus help to identify more accurately those at risk and to provide opportunities for the development of improved treatment.

Characterization of mast cell numbers and subtypes in biopsies from the gastrointestinal tract of dogs with lymphocytic-plasmacytic or eosinophilic gastroenterocolitis.

It has been suggested but not proven that hypersensitivity type I reactions are involved in the pathogenesis of canine inflammatory bowel disease (IBD). The main effector cells in type I hypersensitivity reactions are mast cells (MCs). Canine MCs, as human MCs, can be subdivided into three subtypes according to their content of mast cell-specific proteases: tryptase (MCT), chymase (MCC), or tryptase and chymase bearing MCs (MCTC). In this study, numbers and subsets of mast cells were investigated in biopsies from the gastrointestinal tract of dogs with histopathologically confirmed lymphocytic-plasmacytic enteritis (LPE) (n=4), lymphocytic-plasmacytic colitis (LPC) (n=1) and eosinophilic gastroenterocolitis (EGE) (n=11). Paraffin sections of formalin-fixed samples from the stomach, small intestine (duodenum, jejunum, ileum) and colon were stained by using a metachromatic staining method (kresylecht-violet; KEV) and a combined enzyme histochemical and immunohistochemical technique for chymase and tryptase. Additionally, immunohistochemistry with antibodies against T cells (CD3), macrophages (myeloid/histiocyte antigen) and IgA, IgG and IgM bearing cells was conducted. Quantitative evaluation of mast cells and semiquantitative scoring of immunohistochemically stained cells were performed. Between the two histopathologically defined groups clear differences concerning mast cell numbers were detected. In most affected intestinal tissue locations of dogs with LPE/LPC a decrease in metachromatically (kresylecht-violet) stained granule-containing MCs and immunohistochemically stained MCT,C,TC was found. This reduction could be due to mast cell degranulation, a T helper cell 1 dominated reaction pattern or a "thinning out" due to increasing T cells, IgA and IgG bearing cells. Dogs with EGE displayed higher variability in mast cell numbers but most of the affected large and small intestinal locations had increased numbers of MCs. In these cases, T cells, IgA bearing cells and macrophages also increased. Increased numbers of MCs and eosinophils seen in the intestinal mucosa of dogs with EGE could indicate the presence of a type I hypersensitivity reaction (T helper cell 2 pattern) in response to dietary antigens. Changes in cell numbers occurred also in unaffected locations of dogs with LPE/LPC and EGE which showed reduced MCT,C,TC, increased KEV positive cells and partially increased leucocytes and macrophages.

Acute colitis induction by oil of mustard results in later development of an IBS-like accelerated upper GI transit in mice.

Oil of mustard (OM) is a potent neuronal activator that promotes allodynia and hyperalgesia within minutes of application. In this study, OM was used to induce an acute colitis. We also investigated whether intracolonic OM-induced inflammation alters gastrointestinal (GI) function over a longer time frame as a model of postinflammatory irritable bowel syndrome (PI-IBS). Mice given a single administration of 0.5% OM developed a severe colitis that peaked at day 3, was reduced at day 7, and was absent by day 14. At the peak response, there was body weight loss, colon shrinkage, thickening and weight increases, distension of the proximal colon, and diarrhea. Macroscopic inspection of the distal colon revealed a discontinuous pattern of inflammatory damage and occasional transmural ulceration. Histological examination showed loss of epithelium, an inflammatory infiltrate, destruction of mucosal architecture, edema, and loss of circular smooth muscle architecture. OM administration increased transit of a carmine dye bolus from 58% of the total length of the upper GI tract in untreated age-matched controls to as high as 74% when tested at day 28 post-OM. Mice in the latter group demonstrated a significantly more sensitive response to inhibition of upper GI transit by the mu-opioid receptor agonist loperamide compared with normal mice. OM induces a rapid, acute, and transient colitis and, in the longer term, functional changes in motility that are observed when there is no gross inflammation and thereby is a model of functional bowel disorders that mimic aspects of PI-IBS in humans.

Antinociceptive property of tegaserod in a rat model of chronic visceral hypersensitivity.

OBJECTIVE: To establish a model of chronic visceral hypersensitivity in rats and to investigate the effect of tegaserod, a partial 5-hydroxytryptamine-4 receptor agonist, on visceral hypersensitivity. METHODS: Neonate Sprague-Dawley rats at 8-21 days after birth underwent colorectal distension once daily. Adult rats aged 8-10 postnatal weeks underwent colorectal distension and the abdominal withdrawal reflex (AWR) during the distension was determined. The AWR score was recorded before and after intraperitoneal administration of either tegaserod (treatment group: 0.3 mg/kg) or vehicle (control group). RESULTS: Changes in the AWR score were dependent on the pressure intensity of the colorectal distension (P < 0.01). At pressures of 40, 60 and 80 mmHg, the AWR scores in the model rats with visceral hypersensitivity were significantly higher than those recorded in the control group (1.95 +/- 0.16 vs 1.35 +/- 0.15, 2.82 +/- 0.12 vs 2.17 +/- 0.13, 3.20 +/- 0.14 vs 2.59 +/- 0.14, P < 0.01). Compared with the controls, tegaserod significantly decreased the AWR scores at the distension pressures of 40, 60 and 80 mmHg (1.95 +/- 0.50 vs 1.32 +/- 0.55, 3.05 +/- 0.48 vs 2.32 +/- 0.54, 3.25 +/- 0.63 vs 2.77 +/- 0.51, P < 0.05). CONCLUSIONS: Adult rats can develop chronic visceral hypersensitivity after transient colorectal mechanical irritation during their postnatal period. Tegaserod increases the pain threshold to noxious stimuli, suggesting an antinociceptive property in its effect on visceral hypersensitivity.