Increased expression of fractalkine and its receptor CX3CR1 in canine inflammatory bowel disease and their possible role in recruitment of intraepithelial lymphocytes

The role of endoplasmic reticulum stress in regulation of intestinal barrier and inflammatory bowel disease

Inflammatory bowel disease (IBD) is a chronic inflammatory disease involving the digestive tract, characterized by abdominal pain, diarrhea, rectal bleeding, and so on, which can make patients physically weakened and live difficultly. Although IBD has been recognized for many years, the pathogenesis of IBD has not yet been established and damage to intestinal barrier is thought to be closely associated with IBD. Intestinal barrier is an innate barrier that maintains the homeostasis of the intestinal environment and impedes pathogenic bacteria and toxins, and the endoplasmic reticulum (ER) has recently been found to be involved in maintaining the integrity of intestinal barrier. Endoplasmic reticulum stress (ERS) is a status of endoplasmic reticulum damaged when unfolded or misfolded proteins accumulate in excess of the degradation systematic clearance limit of the misfolded proteins. The regulation of ERS on protein folding synthesis and maintenance of cellular homeostasis is an important factor in influencing the integrity of the intestinal barrier. This paper mainly discusses the relationship between ERS and the intestinal barrier, aiming to understand the regulatory role of ERS on the intestinal barrier and the mechanism and to improve new solutions and notions for the treatment or prevention of IBD.

Plasma amino acid profiles in dogs with inflammatory bowel disease

BACKGROUND

Lymphocytic-plasmacytic enteritis is the common form of idiopathic inflammatory bowel disease (IBD) in dogs. In human IBD, disturbances of amino acid metabolism have been demonstrated to be involved in the pathophysiology of IBD. Therefore, plasma amino acid profile might represent a novel marker of human IBD.

OBJECTIVES

To determine the plasma amino acid profiles of dogs with IBD and its usefulness as a novel marker of IBD in dogs.

ANIMALS

Fasting blood plasma was obtained from 10 dogs with IBD and 12 healthy dogs.

METHODS

All IBD dogs were prospectively included in this study, and heparinized blood samples were collected. The plasma concentrations of 21 amino acids were determined using the ninhydrin method. The relationships among the plasma amino acid concentrations and plasma C-reactive protein (CRP) concentration, canine chronic enteropathy clinical activity index (CCECAI), and overall World Small Animal Veterinary Association (WSAVA) score were investigated.

RESULTS

Median concentration (nmol/mL) of methionine [46.2; range, 30.0-59.3], proline [119.4; range, 76.7-189.2], serine [115.1; range, 61.4-155.9], and tryptophan [17.4; range, 11.9-56.3]) were significantly lower than in control dogs [62.6; range, 51.0-83.6, 199.1; range, 132.5-376.7, 164.3; range, 124.7-222.9, and 68.3; range, 35.7-94.8, respectively]. A negative correlation was identified between the plasma serine concentration and CCECAI (r _s = -.67, P = .03), but there were no correlations between plasma amino acid concentrations and CRP concentration or overall WSAVA score.

CONCLUSIONS AND CLINICAL IMPORTANCE

Plasma serine concentration might represent a novel maker of IBD in dogs.

Comprehensive gene expression analysis of canine invasive urothelial bladder carcinoma by RNA-Seq

BACKGROUND

Invasive urothelial carcinoma (iUC) is a major cause of death in humans, and approximately 165,000 individuals succumb to this cancer annually worldwide. Comparative oncology using relevant animal models is necessary to improve our understanding of progression, diagnosis, and treatment of iUC. Companion canines are a preferred animal model of iUC due to spontaneous tumor development and similarity to human disease in terms of histopathology, metastatic behavior, and treatment response. However, the comprehensive molecular characterization of canine iUC is not well documented. In this study, we performed transcriptome analysis of tissue samples from canine iUC and normal bladders using an RNA sequencing (RNA-Seq) approach to identify key molecular pathways in canine iUC.

METHODS

Total RNA was extracted from bladder tissues of 11 dogs with iUC and five healthy dogs, and RNA-Seq was conducted. Ingenuity Pathway Analysis (IPA) was used to assign differentially expressed genes to known upstream regulators and functional networks.

RESULTS

Differential gene expression analysis of the RNA-Seq data revealed 2531 differentially expressed genes, comprising 1007 upregulated and 1524 downregulated genes, in canine iUC. IPA revealed that the most activated upstream regulator was PTGER2 (encoding the prostaglandin E₂ receptor EP2), which is consistent with the therapeutic efficiency of cyclooxygenase inhibitors in canine iUC. Similar to human iUC, canine iUC exhibited upregulated ERBB2 and downregulated TP53 pathways. Biological functions associated with cancer, cell proliferation, and leukocyte migration were predicted to be activated, while muscle functions were predicted to be inhibited, indicating muscle-invasive tumor property.

CONCLUSIONS

Our data confirmed similarities in gene expression patterns between canine and human iUC and identified potential therapeutic targets (PTGER2, ERBB2, CCND1, Vegf, and EGFR), suggesting the value of naturally occurring canine iUC as a relevant animal model for human iUC.

Immunophenotype of Peripheral Blood Lymphocytes in Dogs with Inflammatory Bowel Disease

Background

Inflammatory bowel disease (IBD) is common in dogs. Despite the known importance of intestinal lymphocytes in its pathogenesis, little is known about the role of peripheral blood lymphocytes (PBLs) in IBD.

Objectives

The aims of this study were (1) comparison of PBLs analyzed by flow cytometry (FCM) in IBD dogs and healthy controls and (2) comparison of PBLs in IBD dogs at the time of diagnosis and in dogs in clinical remission.

Animals

Whole blood samples of 19 IBD dogs at the time of diagnosis and blood samples of 6 dogs in clinical remission were collected. Ten healthy dogs served as controls.

Methods

In this prospective observational study, PBLs were analyzed with multicolor FCM by staining with a panel of anticanine and cross‐reactive monoclonal antibodies against T‐ and B‐cell differentiation antigens, including CD45, CD3, CD4, CD8α, CD8β, TCRαβ, TCRγδ, CD79αcy, and CD21.

Results

The IBD patients’ PBLs had significantly decreased percentages of TCRγδ⁺ T lymphocytes (median: healthy dogs, 3.32; IBD dogs, 0.97; P = 0.03) and CD21⁺ B cells (median: healthy dogs, 27.61; IBD dogs, 17.26; P = 0.04). There were no significant differences in PBLs between pretreatment and follow‐up samples.

Conclusions and Clinical Importance

The differences between PBLs in healthy and IBD dogs analyzed by FCM indicate an imbalance of lymphocytes with different immunologic functions and emphasize the potential value of this technique in a larger cohort of dogs. The PBLs did not differ between IBD dogs before treatment and clinically well‐controlled dogs after treatment.

Endoscopic Cytology for the Diagnosis of Chronic Enteritis and Intestinal Lymphoma in Dogs

Although cytology is a rapid diagnostic procedure in dogs, the cytologic criteria of endoscopic biopsies for chronic enteritis and intestinal lymphoma are not well defined. An immediate diagnosis using cytology would benefit patients by enabling prompt initiation of therapy. The objective of this study was to investigate the correlation between the results of endoscopic cytology and histopathology. In this study, 167 dogs with clinical signs of chronic gastrointestinal disease were included. On the basis of histopathology, the following diagnoses were determined: lymphocytic-plasmacytic enteritis in 93 dogs; eosinophilic enteritis in 5 dogs; small cell intestinal lymphoma in 45 dogs; and large cell intestinal lymphoma in 24 dogs. Two clinical pathologists retrospectively evaluated the endoscopic cytology of squash-smear preparations. The cytologic diagnoses of inflammation, small cell lymphoma, and large cell lymphoma were based on the severity of lymphocyte infiltration, the size of infiltrated lymphocytes, and eosinophil/mast cell infiltration. The clinical severity score was significantly increased along with the degree of lymphocyte infiltration evaluated by cytology. The cytologic diagnosis was in complete agreement with the histopathologic diagnosis in 136 of 167 (81.4%) cases. For the differentiation between enteritis and lymphoma, endoscopic cytology had a sensitivity of 98.6%, a specificity of 73.5%, a positive predictive value of 72.3%, and a negative predictive value of 98.6%. The log-rank test and Cox regression analysis showed that the results of cytology predicted the prognosis. These results suggest that endoscopic cytology is a useful technique to aid diagnosis of intestinal inflammation and lymphoma in dogs.

Changes in Foxp3-Positive Regulatory T Cell Number in the Intestine of Dogs With Idiopathic Inflammatory Bowel Disease and Intestinal Lymphoma

Although regulatory T cells (Tregs) play an integral role in immunologic tolerance and the maintenance of intestinal homeostasis, their involvement in canine gastrointestinal diseases, including idiopathic inflammatory bowel disease (IBD) and intestinal lymphoma, remains unclear. Here we show altered numbers of forkhead box P3 (Foxp3)-positive Tregs in the intestine of dogs with IBD and intestinal lymphoma. IBD was diagnosed in 48 dogs; small cell intestinal lymphoma was diagnosed in 46 dogs; large cell intestinal lymphoma was diagnosed in 30 dogs; and 25 healthy beagles were used as normal controls. Foxp3-positive Tregs in the duodenal mucosa were examined by immunohistochemistry and immunofluorescence. Duodenal expression of interleukin-10 mRNA was quantified by real-time reverse transcription polymerase chain reaction. The number of Foxp3-positive lamina propria cells and the expression of interleukin-10 mRNA were significantly lower in dogs with IBD than in healthy dogs and dogs with intestinal lymphoma. The number of Foxp3-positive intraepithelial cells was higher in dogs with small cell intestinal lymphoma. Some large cell intestinal lymphoma cases had high numbers of Foxp3-positive cells, but the increase was not statistically significant. Double-labeling immunofluorescence showed that CD3-positive granzyme B-negative helper T cells expressed Foxp3. In small cell intestinal lymphoma cases, the overall survival of dogs with a high Treg density was significantly worse than that of dogs with a normal Treg density. These results suggest that a change in the number of Foxp3-positive Tregs contributes to the pathogenesis of canine IBD and intestinal lymphoma by disrupting mucosal tolerance and suppressing antitumor immunity, respectively.

Phenotypic characterization of canine intestinal intraepithelial lymphocytes in dogs with inflammatory bowel disease

Background

Many dogs suffering from inflammatory bowel disease (IBD) are presented to veterinary clinics. These patients are diagnosed based on a history of chronic gastrointestinal signs and biopsy‐confirmed histopathologic intestinal inflammation. Intestinal intraepithelial lymphocytes (IEL) are part of the first line of defense in the gastrointestinal immune system. Alterations in IEL subsets may play a role in the pathogenesis of IBD.

Hypothesis

The aim of this study was to characterize the phenotypes of IEL in dogs with IBD compared with healthy control dogs.

Animals

Intestinal intraepithelial lymphocytes subpopulations of control dogs (n = 5) obtained from endoscopic biopsies (EB) were compared to those obtained from full thickness biopsies (FTB) on the same day. In addition, the phenotypes of IEL from FTB of control dogs (n = 10) were compared with EB of IBD dogs (n = 10). Each participant was scored clinically using the canine inflammatory bowel disease activity index (CIBDAI), and all samples were graded histopathologically. Three‐color flow cytometry of isolated IEL was performed using monoclonal antibodies against T‐ and B‐lymphocyte subpopulations.

Results

No significant differences in the composition of IEL subpopulations were found in control dogs based on method of biopsy. The IBD dogs had significantly higher CIBDAI and histopathologic scores compared with control dogs and their IEL contained a significantly higher frequency TCRγδ T‐cells.

Conclusions and Clinical Importance

Endoscopic biopsies provide suitable samples for 3‐color flow cytometry when studying canine intestinal IEL and IBD patients show significant changes of major T‐cell subsets compared to healthy control dogs.

CX3CR1(+) B cells show immune suppressor properties

The immune regulatory functions of B cells are not fully understood yet. The present study aims to characterize a subtype of B cells that expresses CX3CR1. In this study, peripheral blood samples were collected from patients with food allergies and healthy subjects. Peripheral B cells were analyzed by flow cytometry. T cell proliferation was assessed by carboxyfluorescein succinimidyl ester dilution assay. The results showed that the CX3CR1(+) B cells were detected in the peripheral blood samples of healthy subjects and were significantly less in patients with food allergies. CX3CR1(+) B cells expressed high levels of TGF-β and integrin αvβ6. CX3CR1(+) B cells could efficiently suppress other effector CD4(+) T cell activation. We conclude that human peripheral CX3CR1(+) B cells have immune suppressor properties.

Intestinal protease-activated receptor-2 and fecal serine protease activity are increased in canine inflammatory bowel disease and may contribute to intestinal cytokine expression

Serine proteases elicit cellular responses via protease-activated receptor-2 (PAR-2) which is known to regulate inflammation and the immune response. Although the gastrointestinal tract is exposed to large amounts of proteolytic enzymes, the role of PAR-2 in canine inflammatory bowel disease (IBD) remains unclear. The objective of this study was to investigate the effects of PAR-2 activation on inflammatory cytokine/chemokine gene expression in canine intestine and the expression of intestinal PAR-2 and fecal serine protease activity in dogs with IBD. Duodenal biopsies from healthy dogs were cultured and treated ex vivo with trypsin or PAR-2 agonist peptide, and inflammatory cytokine/chemokine gene expression in the tissues was then quantified by real-time PCR. PAR-2 mRNA and protein expression levels in the duodenal mucosa were examined by real-time PCR and immunohistochemistry, respectively. Fecal serine protease activity was determined by azocasein assay. In ex vivo-cultured duodenum, trypsin and PAR-2 agonist peptide induced significant up-regulation of mRNA expression levels of interleukin-1 β (IL-1β), IL-8, mucosae-associated epithelial chemokine (MEC) and fractalkine, and this up-regulation was inhibited by a serine protease inhibitor. Duodenal PAR-2 mRNA and protein expression levels were higher in dogs with IBD than in healthy control dogs. Fecal serine protease activity was significantly elevated in dogs with IBD, and the level of activity correlated positively with the clinical severity score. These results suggest that PAR-2 may contribute to the pathogenesis of canine IBD by inducing expression of inflammatory mediators in response to luminal serine proteases.

Decreased immunoglobulin A concentrations in feces, duodenum, and peripheral blood mononuclear cells of dogs with inflammatory bowel disease

BACKGROUND

Although immunoglobulin A (IgA) plays a key role in regulating gut homeostasis, its role in canine inflammatory bowel disease (IBD) is unknown.

HYPOTHESIS

IgA expression may be altered in dogs with IBD, unlike that observed in healthy dogs and dogs with other gastrointestinal diseases.

ANIMALS

Thirty-seven dogs with IBD, 10 dogs with intestinal lymphoma, and 20 healthy dogs.

METHODS

Prospective study. IgA and IgG concentrations in serum, feces, and duodenal samples were measured by ELISA. IgA(+) cells in duodenal lamina propria and IgA(+) CD21(+) peripheral blood mononuclear cells (PBMCs) were examined by immunohistochemistry and flow cytometry, respectively. Duodenal expression of the IgA-inducing cytokine transforming growth factor β (TGF-β), B cell activating factor (BAFF), and a proliferation-inducing ligand (APRIL) was quantified by real-time RT-PCR.

RESULTS

Compared to healthy dogs, dogs with IBD had significantly decreased concentrations of IgA in fecal and duodenal samples. The number of IgA(+) CD21(+) PBMCs and IgA(+) cells in duodenal lamina propria was significantly lower in dogs with IBD than in healthy dogs or dogs with intestinal lymphoma. Duodenal BAFF and APRIL mRNA expression was significantly higher in IBD dogs than in the healthy controls. Duodenal TGF-β mRNA expression was significantly lower in dogs with IBD than in healthy dogs and dogs with intestinal lymphoma.

CONCLUSIONS AND CLINICAL IMPORTANCE

IBD dogs have decreased IgA concentrations in feces and duodenum and fewer IgA(+) PBMCs, which might contribute to development of chronic enteritis in dogs with IBD.

Safety and tolerability of Lactobacillus reuteri DSM 17938 and effects on biomarkers in healthy adults: results from a randomized masked trial. PLoS One. 2012;7:e43910. [PMID: 22970150 PMCID: PMC3435331 DOI: 10.1371/journal.pone.0043910]

Background

There are few carefully-designed studies investigating the safety of individual probiotics approved under Investigational New Drug policies.

Objectives

The primary aim of this prospective, double-blind placebo-controlled trial was to investigate if daily treatment of adults with Lactobacillus reuteri DSM 17938 (LR) for 2 months is safe and well-tolerated. Our secondary aim was to determine if LR treatment has immune effects as determined by regulatory T cell percentages, expression of toll-like receptors (TLR)-2 and −4 on circulating peripheral blood mononuclear cells (PMBCs), cytokine expression by stimulated PBMC, and intestinal inflammation as measured by fecal calprotectin.

Methods

Forty healthy adults were randomized to a daily dose of 5×10⁸ CFUs of LR (n = 30) or placebo (n = 10) for 2 months. Participants completed a daily diary card and had 7 clinic visits during treatment and observation.

Results

There were no severe adverse events (SAEs) and no significant differences in adverse events (AEs). There were no differences in PBMC subclasses, TLRs, or cytokine expression after treatment. The probiotic-treated group had a significantly higher fecal calprotectin level than the placebo group after 2 months of treatment: 50 µg/g (IQR 24–127 µg/g) vs. 17 µg/g (IQR 11–26 µg/g), p = 0.03, although values remained in the normal clinical range (0–162.9 µg/g). LR vials retained >10⁸ CFUs viable organisms/ml.

Conclusions

LR is safe and well tolerated in adults, without significant changes in immunologic markers. There was a small but significant increase in fecal calprotectin, perhaps indicating some element of immune recognition at the intestinal level.

Trial Registration

Clinical Trials.gov NCT00922727