Microbiome, Diet, Gastrointestinal Disease and Dysbiosis

Intestinal microbiota is the set of microorganisms (bacteria, fungi, archaea, protozoa, and viruses) present inside the gut; bacteria are of fundamental importance because they help maintain gut homeostasis by competing with pathogens, by regulating energy metabolism and also producing immunomodulatory substrates such as short-chain fatty acids (i.e. acetate, propionate, butyrate). Shifts in microbial communities are due to disease, drug administration, diet, etc., and in recent years, the study of gut microbiome (DNA-based techniques) has better defined/characterized this relationship in many cases. The link between microbiome (dysbiosis) and health and disease is very complex and still far to be completely understood. We wanted to underline the importance of diet in modulating gut microbiome, possibly a useful tool also in term of disease prevention, and of microbial-microbial signaling. Even more we wanted to stress that it will be fundamental to better characterize dysbiosis, cause this may guide treatment decisions

Cholestyramine treatment in two dogs with presumptive bile acid diarrhoea: a case report

Background: In people, bile acid diarrhoea is a prevalent complication of Crohn’s disease and diarrhoea- associated irritable bowel syndrome. Affected patients typically respond to bile acid sequestrants, such as cholestyramine, but human gastroenterologists often fail to recognize bile acid diarrhoea. Consequently, bile acid diarrhoea is regarded as an underrecognized and undertreated condition in human medicine. Due to lack of diagnostic tools, clinical response to bile acid sequestrants is often used to confirm a diagnosis of bile acid diarrhoea in people. Several recent studies have shown that bile acid dysmetabolism also occurs in dogs with chronic enteropathies. It has further been shown that dogs with chronic enteropathies have significantly decreased expression of a bile acid transport protein in the ileum compared to healthy dogs, which correlates with faecal bile acid dysmetabolism. Consequently, in spite of the lack of reports in the literature, bile acid diarrhoea is likely to exist in dogs as well. Case descriptions: Two dogs, an 8-year old Rottweiler and a 4.5-year old Siberian Husky were evaluated for chronic watery diarrhoea. Neither dog responded to dietary trials, probiotics, cyclosporine, faecal microbial transplantations or metronidazole. One of the dogs responded to high daily doses of corticosteroids, which were however associated with unacceptable side effects. The other dog was refractory to all standard treatment protocols, including cyclosporine and corticosteroids. Since none of the dogs responded satisfactorily to standard treatment or modulation of the intestinal microbiome, a suspicion of possible bile acid diarrhoea was raised. Treatment with cholestyramine, a bile acid sequestrant was initiated and resulted in marked improvement of faecal consistency, frequency of defecation and activity level in both dogs. Conclusion: This report presents two dogs with presumed bile acid diarrhoea that were successfully treated with cholestyramine. Therefore, bile acid diarrhoea should be considered as a possible diagnosis in dogs with treatment-refractory chronic diarrhoea. Keywords: Bile acids, Diarrhoea, Dog, CholestyraminePeer reviewe

Assessment of the canine intestinal microflora using molecular methods and serum markers

Previous studies examining the canine intestinal microflora have focused on cultivation of bacteria from intestinal content. Recently, it has been recognized that the majority of bacteria cannot be identified using standard culture techniques. The aim of this study was to describe the composition and dynamics of the canine intestinal microflora using molecular methods based on identification of the 16S ribosomal DNA (16S rDNA) and to evaluate the clinical use of a 13C-glycocholic acid blood test (13CGCBT) as a serum marker for small intestinal bacterial biomass. Intestinal content was obtained from healthy dogs and the microflora was characterized in different compartments of each dog by denaturing gradient gel electrophoresis (DGGE) and comparative 16S rDNA analysis. A 13C-glycocholic acid blood test (13C-GCBT) was developed as a marker for small intestinal bacterial biomass and the influence of tylosin administration on the 13C-GCBT, serum concentrations of cobalamin, folate, and unconjugated cholic acid (SUCA) was evaluated. There was marked variation in DGGE profiles between individual dogs and also between different intestinal compartments within dogs. DGGE profiles from duodenal juice samples collected endoscopically at different time-points varied within individuals, possibly due to variations over time or a slight variation in sampling location. Direct sequencing revealed 106 individual 16S rDNA sequences. Forty-two sequences showed less than 98% similarity to described sequences in public databases and may constitute previously uncharacterized bacterial species. Serum folate concentrations, SUCA, and the cumulative percent dose/min of 13C administered as 13C-glycocholic acid (CUMPCD) increased significantly following tylosin administration (p<0.01). The results indicate that dogs have a complex intestinal microflora with marked differences between individual dogs. Different intestinal compartments appear to host a unique microflora and the assessment of a fecal sample does not yield accurate information about the composition of the microflora in proximal compartments of the gut. The intestine harbors many previously uncharacterized bacterial species. The clinical significance of these uncharacterized intestinal bacterial species needs to be further investigated in dogs with gastrointestinal disease. Increased serum folate, SUCA, and CUMPCD in the 13C-GCBT suggest that, in the dogs described here, tylosin administration increased the biomass of organisms carrying out these metabolic functions

Small hiatal hernia as a risk factor of atrial fibrillation

Purpose: Hiatal hernia (HH) is considered a risk factor of atrial fibrillation (AF). The aim of this study was to evaluate HH in computed tomography (CT) images in patients awaiting ablation due to atrial fibrillation, and to look for a correlation between HH in patients without AF and with AF. Material and methods: This study included 441 patients divided in two groups: 207 patients subjected to computed tomography before ablation procedure due to atrial fibrillation and 234 patients as the control group, who underwent CT scans to rule out coronary disease (no AF in history). Results: Small HH, e.g. under or equal to 2 cm, are associated with a higher risk of AF compared to the control group, which was not observed for bigger HH. Conclusions: The presence of small HH may be a risk factor of AF

Whole carcass diets: a role for fibre in gastrointestinal health of cheetahs?

This study was undertaken to test the hypothesis that altered podocyte slit protein nephrin distribution is associated with disturbed polarity protein expressions in podocytes from preeclampsia (PE). We examined expressions and distributions of nephrin, podoplanin, polarity protein partitioning defective-3 (PARD-3), and PARD-6 in podocytes from PE. Podocyte cell line (AB 8/13 cells) was used as control. Podocytes were found in all severe PE cases. In contrast, no podocyte was found in the samples from normal pregnancies and mild PE. Compared to control cells, nephrin, PARD-3 and PARD-6 expressions were reduced or lost in podocytes from severe PE. Podoplanin was expressed in podocyte surface membrane on control cells but reduced in podocytes from PE. These findings indicate that loss of slit protein nephrin and polarity protein PARD-3 and PARD-6 on foot processes could explain for podocyte detachment from glomerular basement membrane and lead to podocyte shedding in PE. © The Author(s) 2011.link_to_subscribed_fulltex

Understanding the canine intestinal microbiota and its modification by pro-, pre- and synbiotics – what is the evidence?

Interest in the composition of the intestinal microbiota and possibilities of its therapeutic modifications has soared over the last decade and more detailed knowledge specific to the canine microbiota at different mucosal sites including the gut is available. Probiotics, prebiotics or their combination (synbiotics) are a way of modifying the intestinal microbiota and exert effects on the host immune response. Probiotics are proposed to exert their beneficial effects through various pathways, for example production of antimicrobial peptides, enhancing growth of favourable endogenous microorganisms, competition for epithelial colonisation sites and immune-modulatory functions. Despite widespread use of pro-, pre- and synbiotics, scientific evidence of their beneficial effects in different conditions of the dog is scarce. Specific effects of different strains, their combination or their potential side-effects have not been evaluated sufficiently. In some instances, in vitro results have been promising, but could not be transferred consistently into in vivo situations. Specific canine gastrointestinal (GI) diseases or conditions where probiotics would be beneficial, their most appropriate dosage and application have not been assessed extensively. This review summarises the current knowledge of the intestinal microbiome composition in the dog and evaluates the evidence for probiotic use in canine GI diseases to date. It wishes to provide veterinarians with evidence-based information on when and why these products could be useful in preventing or treating canine GI conditions. It also outlines knowledge about safety and approval of commercial probiotic products, and the potential use of faecal microbial transplantation, as they are related to the topic of probiotic usage

INTESTINAL MICROBIOTA IN LYMPHOMA: A COMPARISON IN HEALTY DOGS AND DOGS WITH NON HODGKIN LYMPHOMA

Background and objectives Animal models play a key role in understanding the importance of gut microbiome in immune development and composition as well as to reinforce the relationship between the microbiota and health and disease. Intestinal bacteria have been implicated in several types of cancer. Regardless, microbes influence immune cells directly, indirectly, or both, and increased lymphocyte proliferation can lead to a higher chance of aberrant DNA replication. This particularly occurs with some B lymphocytes which are innately vulnerable to genetic instability and activation. Methods We analyzed the microbiome (by using 16S rRNA gene sequencing and qPCR assays) of naturally voided fecal samples from 12 healthy and 12 Non Hodgkin Lymphoma (NHL) dogs in order to evaluate the microbiota composition using a dysbiosis index. An index value greater than 2 indicates dysbiosis, while below 0 indicates normal microbiota. Results. Significant differences were observed when comparing the fecal microbiota structure of all healthy dogs vs NHL dogs (ANOSIM; P&lt;0.05). Specifically, differences were observed for Faecalibacterium (P&lt;0.001) with concentrations higher in healthy vs NHL dogs. The dysbiosis index was significantly lower (p=0.007) in healthy vs NHL dogs (mean, SD: H2.6, 2.0 vs 1.7, 3.2), respectively. Conclusion Interestingly, lower levels of Fecalibacterium prausnitzii were recently found in humans with some chronic colonic conditions as well as colorectal cancer (P &lt; 0.001) compared with healthy subjects. This study showed that NHL have a increased dysbiosis index, indicating dysbiosis. Animal models of cancer can be critical in order to demonstrate a link between the microbiome and carcinogenesis

Fecal microbiota differences in Non-Hodgkin Lymphoma (NHL) affected dogs: preliminary results.

Animal models play an essential role in understanding the importance of gut microbiome in immune development and composition, and play a key role to reinforce the relationship between the microbiome and health and disease [3]. Non-Hodgkin Lymphoma (NHL) is the most common hematopoietic malignancy in dogs, caused by clonal proliferation of lymphocytes in solid organs [2]. Whether microbes influence immune cells directly, indirectly, or both, increased lymphocyte proliferation can lead to a higher chance of aberrant DNA replication, particularly in some B lymphocytes which are innately vulnerable to genetic instability and activation. Oxidative stress caused by intestinal microbiota, either directly or indirectly through the immune system, can also affect tumorigenesis, thus, the microbiota can affect several pathways associated with lymphomagenesis [4]. The optimal responses to cancer therapy require an intact commensal microbiota that mediates its effects, by modulating myeloid derived cell functions in the tumour microenvironment [1]. In our study design we analysed the microbiome (by using 16S rRNA gene 454-pyrosequencing and qPCR assays) of naturally voided fecal samples from 6 healthy dogs, 8 NHL dogs before and 4 NHL (of the eight) dogs after induction phase of chemotherapy (cyclophosphamide, vincristine, and prednisolone) plus probiotics (Sivoy TM). Several statistical significances were observed compared the fecal microbiome of healthy dogs vsNHL dogs before chemotherapy. In particular, differences were observed for Bifidobacteria (p=0.0001), Lactobacillus (p=0.0001), Faecalibacterium (p=0.0005), Bacteroidetes (p=0.0480), and Fusobacterium (p=0.0025), which concentrations were higher in healthy dogs compared to NHL dogs. On the contrary, the concentration of Clostridium perfrigens was greater in NHL dogs compared to healthy dogs (p=0.0326). No statistical differences for total bacteria, Escherichia coli, Blautia, and Ruminococcaceae were found. Microbiome shift (total bacteria, Bifidobacteria, Lactobacillus, Faecalibacterium, Bacteroidetes, Fusobacterium, Escherichia coli, Blautia, Ruminococcaceae, and Clostridium perfrigens) of fecal samples were also compared before and after induction phase of chemotherapy plus probiotics (Sivoy TM probiotic mix Slab51, containing 8 strains of lactic acid bacteria and bifidobacteria dosed at 200 billion per stick) but no statistical significance was found. In order to understand microbiome’s changes in NHL affected dogs treated with standard protocol plus probiotics, a larger number of stool samples before and after treatment, from a greater number of animals, should be investigated. The fact that an increased number of lymphomas are becoming associated with bacterial infections underscores the need for more studies involving microbes and lymphoma and about the use of probiotics to restore normal microbiota in affected dogs

Salmonella Typhimurium and Multidirectional Communication in the Gut

The mammalian digestive tract is home to trillions of microbes, including bacteria, archaea, protozoa, fungi and viruses. In monogastric mammals the stomach and small intestine harbor diverse bacterial populations but are typically less populated than the colon. The gut bacterial community (microbiota hereafter) varies widely among different host species and individuals within a species. It is influenced by season of the year, age of the host, stress and disease. Ideally, the host and microbiota benefit each other. The host provides nutrients to the microbiota and the microbiota assists the host with digestion and nutrient metabolism. The resident microbiota competes with pathogens for space and nutrients and, through this competition, protects the host in a phenomenon called colonization resistance. The microbiota participates in development of the host immune system, particularly regulation of autoimmunity and mucosal immune response. The microbiota also shapes gut-brain communication and host responses to stress; and, indeed, the microbiota is a newly recognized endocrine organ within mammalian hosts.Salmonella enterica serovar Typhimurium (S. Typhimurium hereafter) is a food-borne pathogen which adapts to and alters the gastrointestinal (GI) environment. In the GI tract, S. Typhimurium competes with the microbiota for nutrients and overcomes colonization resistance to establish infection. To do this, S. Typhimurium uses multiple defense mechanisms to resist environmental stressors, like the acidic pH of the stomach, and virulence mechanisms which allow it to invade the intestinal epithelium and disseminate throughout the host. To coordinate gene expression and disrupt signaling within the microbiota and between host and microbiota, S. Typhimurium employs its own chemical signaling and may regulate host hormone metabolism.This review will discuss the multidirectional interaction between S. Typhimurium, host and microbiota as well as mechanisms that allow S. Typhimurium to succeed in the gut