In vivo measurement of intragastric pressure with a rubber balloon in the anesthetized rat.

The protocols described in this unit are designed to measure the intragastric pressure in anesthetized rats by a water-filled low-compliance rubber balloon. The balloon is introduced into the stomach either orally (by passing the balloon down the esophagus) or directly via a small incision of the fundus after laparotomy. The effects of both stimulatory (e.g., carbachol) and inhibitory (e.g., oxymetazoline) agents can be evaluated on the gastric tone and phasic contractions. The model allows the evaluation of dose-response curves and also the time-course of the effects. Furthermore, by combining centrally or peripherally acting agents the site of action can also be determined. Curr. Protoc. Toxicol. 57:21.12.1-21.12.11. (c) 2013 by John Wiley & Sons, Inc

Role of cannabinoids in gastrointestinal mucosal defense and inflammation.

Modulating the activity of the endocannabinoid system influences various gastrointestinal physiological and pathophysiological processes, and cannabinoid receptors as well as regulatory enzymes responsible for the synthesis or degradation of endocannabinoids represent potential targets to reduce the development of gastrointestinal mucosal lesions, hemorrhage and inflammation. Direct activation of CB1 receptors by plant-derived, endogenous or synthetic cannabinoids effectively reduces both gastric acid secretion and gastric motor activity, and decreases the formation of gastric mucosal lesions induced by stress, pylorus ligation, nonsteroidal anti-inflammatory drugs (NSAIDs) or alcohol, partly by peripheral, partly by central mechanisms. Similarly, indirect activation of cannabinoid receptors through elevation of endocannabinoid levels by globally acting or peripherally restricted inhibitors of their metabolizing enzymes (FAAH, MAGL) or by inhibitors of their cellular uptake reduced the gastric mucosal lesions induced by NSAIDs in a CB1 receptor-dependent fashion. Dual inhibition of FAAH and cyclooxygenase induced protection against both NSAID-induced gastrointestinal damage and intestinal inflammation. Moreover, in intestinal inflammation direct or indirect activation of CB1 and CB2 receptors exerts also multiple beneficial effects. Namely, activation of both CB receptors was shown to ameliorate intestinal inflammation in various murine colitis models, to decrease visceral hypersensitivity and abdominal pain, as well as to reduce colitis-associated hypermotility and diarrhea. In addition, CB1 receptors suppress secretory processes and also modulate intestinal epithelial barrier functions. Thus, experimental data suggest that the endocannabinoid system represents a promising target in the treatment of inflammatory bowel diseases, and this assumption is also confirmed by preliminary clinical studies

Gut inflammation: current update on pathophysiology, molecular mechanism and pharmacological treatment modalities

Inflammatory bowel disease (IBD) is a chronic and relapsing inflammatory condition of the gastrointestinal tract. The two main forms of IBD are Crohn's disease and ulcerative colitis. According to the recent concept the disease is caused by a combination of factors, including genetics, immune dysregulation, barrier dysfunction and the change in microbial flora. Environmental factors, such as changes in diet, antibiotic use, smoking or improved domestic hygiene (e.g. eradication of intestinal helminths) probably contribute to the development and increased prevalence of IBD. Dysregulation of mucosal immunity in IBD causes an overproduction of inflammatory cytokines which resulted in uncontrolled intestinal inflammation. Based on extensive research over the last decade, besides the conventional therapy, there are several novel pathways and specific targets, on which focus new therapeutics. New therapeutics aim 1./ to correct genetic susceptibility by stimulating NOD2 expression, TLR3 signaling or inhibition of TLR4 pathway, 2./ to restore the immune dysregulation by inhibition of pro-inflammatory cytokines (TNF-α, IL-6, IL-13, IL-17, IL-18, IL-21), Th1 polarisation (IL-2, IL-12, IL-23, IFN-γ ), T-cell activation, leukocyte adhesion, as well as by immunostimulation (GM-CSF, G-CSF) and anti-inflammatory cytokines (IL-10, IL-11, IFN-β-1a), 3./ to restore mucosal barrier function and stimulate mucosal healing by different growth factors, such as GH, EGF, KGF, TGF-β, VEGF, 4./ to restore the normal bacterial flora by antibiotics, probiotics. However, in spite of these numerous potential targets, the true value and clinical significance of most of the new biologics and molecules are not clear yet

Comparative in vivo analysis of recombinant type II feline coronaviruses with truncated and completed ORF3 region.

Our previous in vitro comparative study on a feline coronavirus (FCoV) pair, differing only in the intactness of their ORF3abc regions, showed that the truncated ORF3abc plays an important role in the efficient macrophage/monocyte tropism of type II feline infectious peritonitis virus (FIPV). In the present study, we describe a challenge experiment with the same recombinant FCoVs in order to gain data on the in vivo characteristics on these viruses. While parent virus FIPV DF-2 developed feline infectious peritonitis in all the infected cats, its recombinant virus PBFIPV-DF-2, differing only in seven nucleotides, proved to be surprisingly low virulent, although caused an acute febrile episode similarly to the original FIPV DF-2. PBFIPV-DF-2 infection induced significantly lower virus neutralization titers than its parent virus, and lacked the second phase of viremia and development of fatal course of the disease. The recombinant PBFIPV-DF-2-R3i with completed ORF3abc gained biological properties that differentiate between the feline enteric coronavirus (FECV) and FIPV biotypes such as intensive replication in the gut, absence of viremia and weak or no serological response. Using reverse genetic approaches our study is the first experimental proof that ORF3abc is indeed responsible for the restriction of FECV replication to the intestine in vivo

Recombinant feline coronaviruses as vaccine candidates confer protection in SPF but not in conventional cats.

Feline infectious peritonitis virus (FIPV) is a major pathogen of Felidae. Despite the extensive efforts taken in the past decades, development of the "ideal" live attenuated FIPV vaccine was not successful yet. In the present study, we provide data of immunisation experiments with a recombinant FCoV pair differing only in the truncation (PBFIPV-DF-2) or completion (PBFIPV-DF-2-R3i) of their ORF3abc regions. In our previous in vivo studies, these viruses proved to show the characters of low virulent or avirulent FCoV phenotypes, respectively. Therefore, we hypothesised the ability of these viruses, as possible vaccine candidates, in conferring protection in specific pathogen free (SPF) Domestic Shorthair as well as in conventional purebred British Shorthair cats. In SPF cats, after two oronasal and two intramuscular vaccinations with two weeks intervals, both vaccine candidates provided 100% protection against lethal homologous challenge with the highly virulent FIPV DF-2 strain. In contrast, the conventional purebred British Shorthair cats did not develop protection when they were immunised with the same vaccination regimes. In these groups 100% of the PBFIPV-DF-2-R3i immunised animals developed antibody-dependent enhancement (ADE). Prolonged survival was observed in 40% of the animals, while 60% showed fulminant disease course. Genetic and more probably immunological differences between the SPF and non-SPF purebred kittens can explain the different outcome of the vaccination experiment. Our data highlight the diverse immune responses between SPF and conventional cats and suggest a decisive role of previous infection by heterologous causative agents in the outcome of the vaccination against FIP

Immunological and biochemical characterisation of 7ap, a short protein translated from an alternative frame of ORF7 of PRRSV

Sequence analysis revealed a short alternative open reading frame (ORF) named ORF7a within the nucleocapsid gene of genetically divergent porcine reproductive and respiratory syndrome virus (PRRSV) genomes. Alignment of the corresponding protein sequences (named 7ap) revealed substantial heterogeneity among 7aps of different genotypes, though all of them are predicted to be positively charged. Green fluorescent protein and FLAG fusion constructs of ORF7a of the HU-14432/2011 PRRSV demonstrated that 7ap is expressed. 7ap of HU- 14432/2011 (Hu7ap) was synthesised chemically, and ELISA experiments revealed that Hu7ap binds strongly to mammalian IgGs. Protein-protein gel retardation assays and complement fixation inhibition suggest that 7aps bind to the CH2 domain of the IgG(Fc) fragment. Cellular localisation and immunological characteristics of PRRSV 7ap may indicate multiple functions including nuclear and cytoplasmic over-tuning of normal cellular processes and immunosuppression

Characterisation of the nucleic acid binding features of the PRRSV 7ap and its ability to induce antinuclear antibodies

A short alternative open reading frame named ORF7a has recently been discovered within the nucleocapsid gene of the porcine reproductive and respiratory syndrome virus (PRRSV) genome. Proteins (7ap) translated from the ORF7a of two divergent strains — a type I and a type II — are able to completely reduce the motility of nucleic acids at relatively high molar charge ratios in gel retardation assays indicating strong dsDNA- and ssRNA-binding capability. Conserved RNA- and DNA-binding properties suggest that nucleic acid binding is a functional property of the divergent 7aps, and not an arbitrary consequence of their net positive charge. Sera from Hu7ap-immunised pigs and mice did not react with Hu7ap or Hu7ap-GFP; however, antinuclear antibodies were detected in the sera of the immunised animals, suggesting an ability of Hu7ap to interact with or mimic autoantigenic macromolecules

Full-length genome sequence analysis of a Hungarian Porcine Reproductive and Respiratory Syndrome Virus isolated from severe respiratory disease

The authors report the isolation of a Type 1 PRRSV strain from a clinical outbreak of severe respiratory problems and high fever. Next generation sequencing was used to determine the complete genome sequence of the isolate (9625/2012). The virus belongs to a new branch within subtype 1, clade D, containing mostly Spanish sequences and shows highest similarity to PRRSV Olot/1991 and to the Amervac vaccine strain. SimPlot analysis performed with the available full-length genome sequences indicates no evidences of recombination. Mutation analysis of 9625/2012 and the most related strains revealed high proportion of amino acid substitutions in the putative neutralizing epitopes, suggesting an important role of the selective immune pressure in the evolution of PRRSV 9625/2012

Cellular localisation of the proteins of region 3 of feline enteric coronavirus

Feline enteric coronaviruses have three open reading frames (ORFs) in region 3 (3a, 3b, and 3c). All three ORFs were expressed with C-terminal eGFP and 3xFLAG tags in different cell lines and their localisation was determined. ORF 3a is predicted to contain DNA-binding and transcription activator domains, and it is localised in the nucleus and in the cytoplasm. ORF 3b is also predicted to contain DNA-binding and activator domains, and was found to localise in the mitochondrion. Besides that, in some of the non-infected and FIPV-infected cells nucleolar, perinuclear or nuclear membrane accumulation of the eGFP-tagged 3b was observed. The exact compartmental localisation of ORF 3c is yet to be determined. However, based on our co-localisation studies 3c does not seem to be localised in the ER-Golgi network, ERGIC or peroxisomes. The expression of 3c-eGFP is clearly cell type dependent, it is more stable in MARC 145 cells than in Fcwf-4 or CrFK cells, which might reflect in vivo stability differences of 3c in natural target cells (enterocytes vs. monocytes/macrophages)