Immune-mediated hematological disease in dogs is associated with alterations of the fecal microbiota: a pilot study

BACKGROUND

The dog is the most popular companion animal and is a valuable large animal model for several human diseases. Canine immune-mediated hematological diseases, including immune-mediated hemolytic anemia (IMHA) and immune thrombocytopenia (ITP), share many features in common with autoimmune hematological diseases of humans. The gut microbiome has been linked to systemic illness, but few studies have evaluated its association with immune-mediated hematological disease. To address this knowledge gap, 16S rRNA gene sequencing was used to profile the fecal microbiota of dogs with spontaneous IMHA and ITP at presentation and following successful treatment. In total, 21 affected and 13 healthy control dogs were included in the study.

RESULTS

IMHA/ITP is associated with remodeling of fecal microbiota, marked by decreased relative abundance of the spirochete Treponema spp., increased relative abundance of the pathobionts Clostridium septicum and Escherichia coli, and increased overall microbial diversity. Logistic regression analysis demonstrated that Treponema spp. were associated with decreased risk of IMHA/ITP (odds ratio [OR] 0.24-0.34), while Ruminococcaceae UCG-009 and Christensenellaceae R-7 group were associated with increased risk of disease (OR = 6.84 [95% CI 2-32.74] and 8.36 [95% CI 1.85-71.88] respectively).

CONCLUSIONS

This study demonstrates an association of immune-mediated hematological diseases in dogs with fecal dysbiosis, and points to specific bacterial genera as biomarkers of disease. Microbes identified as positive or negative risk factors for IMHA/ITP represent an area for future research as potential targets for new diagnostic assays and/or therapeutic applications.

Exploring the role of immune checkpoint inhibitors in the etiology of myasthenia gravis and Lambert-Eaton myasthenic syndrome: A systematic review

Background

While immune checkpoint inhibitors (ICIs) have been revolutionary in the treatment of cancer, their administration has been associated with a variety of immune-related adverse events (irAEs), including myasthenia gravis (MG), and Lambert-Eaton myasthenic syndrome (LEMS).

Objective

To provide a comprehensive synthesis of the evidence supporting an etiological role for ICIs in MG and LEMS in patients with no prior history of autoimmune disease.

Hypothesis

ICIs may trigger MG and LEMS in patients with no prior susceptibility to autoimmune disease.

Methods

Relevant primary research on Medline was interrogated using a series of search algorithms. Search terms were constructed based on the PICOS tool endorsed by the Cochrane Collaboration, which describes population, intervention, comparison, outcomes, and study design. Papers were screened according to inclusion and exclusion criteria. Additional papers were retrieved from the reference lists of screened papers. Each paper included in the qualitative synthesis was assigned an integrated metric of evidence (IME) value, ranging from 0 to 7, based on study design, quality of data, likelihood of a causal link between the immune checkpoint inhibitor(s) and MG/LEMS, confidence of MG/LEMS diagnosis, and the number of patients treated with an ICI prior to MG/LEMS diagnosis.

Results

Ninety-four papers describing at least one patient treated with ICI(s) prior to the onset of MG and/or LEMS were documented. Overall evidence for a causal link between ICI administration and MG/LEMS was low, with a median IME value of 2.88 (range 2.05-6.61).

Conclusions

There is a paucity of evidence in support of an etiological relationship between ICIs and MG/LEMS, due largely to the lack of mechanistic studies and/or prospective clinical trials with relevant study endpoints. The current literature is dominated by case reports and retrospective cohort studies, which inherently yield only low-level evidence, supporting the need for further work in this area. A role of ICIs in the etiology of MG/LEMS remains plausible, arguing for continued vigilance for irAEs in patients treated with these drugs. We argue that there is a need for future mechanistic, high quality, large-scale studies specifically investigating the possible etiological role of ICIs in MG/LEMS.

Systemic immunosuppression promotes survival and integration of subretinally implanted human ESC-derived photoreceptor precursors in dogs

Regenerative therapies aimed at replacing photoreceptors are a promising approach for the treatment of otherwise incurable causes of blindness. However, such therapies still face significant hurdles, including the need to improve subretinal delivery and long-term survival rate of transplanted cells, and promote sufficient integration into the host retina. Here, we successfully delivered in vitro-derived human photoreceptor precursor cells (PRPCs; also known as immature photoreceptors) to the subretinal space of seven normal and three rcd1/PDE6B mutant dogs with advanced inherited retinal degeneration. Notably, while these xenografts were rejected in dogs that were not immunosuppressed, transplants in most dogs receiving systemic immunosuppression survived up to 3–5 months postinjection. Moreover, differentiation of donor PRPCs into photoreceptors with synaptic pedicle-like structures that established contact with second-order neurons was enhanced in rcd1/PDE6B mutant dogs. Together, our findings set the stage for evaluating functional vision restoration following photoreceptor replacement in canine models of inherited retinal degeneration.

•

In vivo multimodal imaging identified early signs of transplant rejection

•

Systemic immunosuppression was necessary for long-term survival of xenotransplants

•

Human donor photoreceptors integrated and differentiated mostly into M/L cones

•

A degenerating retinal environment enhances structural synaptogenesis in PRPCs

Clinical efficacy of prebiotics and glycosaminoglycans versus placebo In dogs with food responsive enteropathy receiving a hydrolyzed diet: A pilot study

Induction of remission is easily achieved with dietary treatment in dogs diagnosed with Food Responsive Chronic Diarrhea (FRD). Administration of prebiotics and glycosaminoglycans (GAGs) may improve epithelial cell integrity and therefore be useful as adjunct treatment. This study evaluated whether the relapse rate of FRD dogs that are switched back to a normal diet can be influenced using supplemental treatment with prebiotics and GAGs. A randomized, controlled clinical trial (RCCT) was performed in dogs diagnosed with FRD. Dogs were diagnosed based on clinical exclusion diagnosis, endoscopic biopsies showing predominantly lymphoplasmacytic infiltration, and response to dietary treatment. Dogs were randomized to be fed a combination of prebiotics and GAGs (group 1) or placebo (group 2) in addition to a hydrolyzed diet. At week 10, a second endoscopy was performed and dogs were switched back to normal diet. Relapse rate was monitored every 2 weeks after that until week 18. Statistical analysis was performed for each outcome (Canine Chronic Enteropathy Clinical Activity Index (CCECAI), clinicopathological data, endoscopic scoring, mWSAVA histological scoring index (mWSAVA), and number of relapses following switch to normal diet) using a linear mixed effects model for group comparison. Time, group, and their interactions were included as a fixed effect, whereas each dog was treated as a random effect. Of the 35 dogs enrolled into the clinical trial, 10 in each group reached the point of second endoscopy. A total of 13 dogs (n = 8 in group 1 and n = 5 in group 2) reached the trial endpoint of 18 weeks. After switching back to normal diet, none of the dogs in either group relapsed. No significant differences were found over time or between groups for CCECAI, endoscopy scoring and histological scoring. Although there was a clinical worsening in the placebo group after switching back to the original diet, this was not statistically significant (CCECAI p = 0.58). Post-hoc power calculation revealed that 63 dogs per group would have been needed to detect statistically significant differences in CIBDAI between treatment groups. Standard dietary treatment induced rapid clinical response in all cases, however, additional supplementation with prebiotics and GAGs did not significantly improve clinical outcome within 4 months after switching back to normal diet. Since there are very few RCCT published in CE in dogs, this pilot study provides important power analyses for planning of further studies.

Clinical features and outcome of acquired myasthenia gravis in 94 dogs

Background

Factors known to be associated with outcome of acquired myasthenia gravis (MG) in dogs are limited.

Hypothesis/Objectives

Of dogs with MG, advancing age and comorbid neoplasia are associated with poor long‐term prognosis and low rates of remission.

Animals

Ninety‐four client‐owned dogs with MG diagnosed by acetylcholine receptor antibody (AChR Ab) assay between 2001 and 2019 from a university clinic and 3 private clinics in the United States.

Methods

Cases were retrospectively evaluated and data were collected to determine clinical signs, treatment, and response to therapy defined by means of a clinical scoring rubric. Immunological remission was defined as a return of the AChR Ab concentration to <0.6 nmol/L. Multivariable binary logistic regression analysis was used to identify clinical criteria predicting remission.

Results

An anticholinesterase drug was used to treat 90/94 (96%) dogs, which in 63/94 (67%) was the sole treatment; other drugs included immune modulators. Clinical remission (lack of clinical signs ≥4 weeks after treatment cessation) was observed in 29 (31% [95% confidence interval (CI): 22.4‐40.8%]) dogs, clinical response (lack of clinical signs on treatment) in 14 (15% [95% CI: 9.0‐23.6%]) dogs, clinical improvement (on treatment) in 24 (26% [95% CI: 17.8‐35.2%]) dogs, and no clinical improvement in 27 (29% [95% CI: 20.5‐38.6%]) dogs. Immunological remission was observed in 27/46 (59%) dogs, with clinical remission in all 27. Younger age (P = .04) and comorbid endocrine disease (P = .04) were associated with clinical remission. Initial AChR Ab concentration (P = .02) and regurgitation (P = .04) were negatively associated with clinical remission.

Conclusions and Clinical Importance

Clinical remission in MG is less likely in older dogs and dogs presenting with regurgitation or high initial AChR Ab concentration, but more likely in younger dogs and dogs with comorbid endocrine disease.

A Systematic Review of the Potential Implication of Infectious Agents in Myasthenia Gravis

Background: Myasthenia gravis (MG) is an autoimmune disorder of unknown etiology in most patients, in which autoantibodies target components of neuromuscular junctions and impair nerve to muscle transmission.

Objective: To provide a synthesis of the evidence examining infectious agents associated with the onset of MG.

Hypothesis: We hypothesized that microbes play a pathogenic role in the initiation of MG. For clinical cases, the onset of clinical signs is used as a proxy for the true onset of autoimmunity.

Methods: We searched PubMed and Web of Science. Papers captured through database searching (n = 827) were assessed, yielding a total of 42 publications meeting the inclusion and exclusion criteria. An additional 6 papers were retrieved from the reference lists of relevant articles. For each pathogen, an integrated metric of evidence (IME) value, from minus 8 to plus 8, was computed based on study design, quality of data, confidence of infectious disease diagnosis, likelihood of a causal link between the pathogen and MG, confidence of MG diagnosis, and the number of infected patients. Negative IME values corresponded to studies providing evidence against a role for microbes as triggers of MG.

Results: One hundred and sixty-nine myasthenic patients infected with 21 different pathogens were documented. Epstein-Barr virus (median = 4.71), human papillomavirus (median = 4.35), and poliovirus (median = 4.29) demonstrated the highest IME values. The total median IME was 2.63 (mean = 2.53; range −3.79–5.25), suggesting a general lack of evidence for a causal link.

Conclusions: There was a notable absence of mechanistic studies designed to answer this question directly. The question of the pathogenic contribution of microbes to MG remains open.

The impact of alfaxalone, propofol and ketamine on canine peripheral blood lymphocyte cytotoxicity in vitro

Anesthetics may worsen the outcome of patients undergoing oncologic surgery via immune suppression. This study examines the impact of propofol, ketamine, and alfaxalone on canine peripheral blood lymphocyte (PBL) cytotoxic function in vitro. PBLs isolated from healthy canine blood were cultured in the presence or absence of alfaxalone, propofol, ketamine, their carrier solutions or dexamethasone as a positive control for 20 h. There was a decrease in cytotoxicity in PBLs exposed to dexamethasone and propofol carrier compared to the control as assessed by means of a chromium-based cytotoxicity assay. The PBLs exposed to propofol carrier also showed lower cytotoxicity compared to propofol. No other significant differences were observed. Therefore, the documented effects of these anesthetics in vivo may be caused by an indirect mechanism. The lipid emulsion's significant decrease in PBL cytotoxicity may have implications for critically ill patients on total parenteral nutrition.

Pharmacokinetics and Pharmacodynamics of Immediate- and Modified-Release Mycophenolic Acid Preparations in Healthy Beagle Dogs

Background: Mycophenolic acid (MPA) is a broad-acting immunomodulating agent that may be therapeutically beneficial for the treatment of immune-mediated diseases in canine patients.

Objectives: To determine the suppressive effects of MPA on T-cell proliferation, and to assess the feasibility of a canine-specific q24 h modified-release MPA formulation (OKV-1001b).

Animals: Fifteen healthy purpose-bred male beagle dogs.

Methods: Two nearly identical open-label fifteen-day studies were conducted in which dogs were randomized to receive mycophenolate mofetil (MMF; 10 mg/kg q12h), or two doses of OKV-1001b (270 mg and 180 mg; q24h). Serial pharmacokinetic (PK) and pharmacodynamic (PD) samples were collected on Days 1, 8, and 15. MPA plasma concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), while an ex vivo T-cell proliferation assay assessed PD effects. Dogs were continuously monitored for evidence of side effects and gastrointestinal tolerability.

Results: MPA induced inhibition of T-cell proliferation was observed following administration of all MPA preparations in a clear concentration-dependent manner. The PK/PD relationship was maintained across all days and time-points. Data generated herein suggest that MPA plasma concentrations above 600 ng/mL achieve at least 50% inhibition of T-cell proliferation.

Conclusions and Clinical Importance: MPA holds therapeutic potential for treating dogs with immune-mediated disease, but clinical trials will be necessary to determine its safety and efficacy in naturally occurring disease. Likewise, q24h oral modified release MPA preparations that maintain MPA plasma concentrations between 600 and 1,000 ng/mL are warranted for further studies in client-owned dogs.

Immunoregulatory Cells in Myasthenia Gravis

Myasthenia gravis (MG) is a T cell-dependent, B-cell mediated autoimmune disease caused by antibodies against the nicotinic acetylcholine receptor or other components of the post-synaptic muscle endplate at the neuromuscular junction. These specific antibodies serve as excellent biomarkers for diagnosis, but do not adequately substitute for clinical evaluations to predict disease severity or treatment response. Several immunoregulatory cell populations are implicated in the pathogenesis of MG. The immunophenotype of these populations has been well-characterized in human peripheral blood. CD4⁺FoxP3⁺ regulatory T cells (Tregs) are functionally defective in MG, but there is a lack of consensus on whether they show numerical perturbations. Myeloid-derived suppressor cells (MDSCs) have also been explored in the context of MG. Adoptive transfer of CD4⁺FoxP3⁺ Tregs or MDSCs suppresses ongoing experimental autoimmune MG (EAMG), a rodent model of MG, suggesting a protective role of both populations in this disease. An imbalance between follicular Tregs and follicular T helper cells is found in untreated MG patients, correlating with disease manifestations. There is an inverse correlation between the frequency of circulating IL-10–producing B cells and clinical status in MG patients. Taken together, both functional and numerical defects in various populations of immunoregulatory cells in EAMG and human MG have been demonstrated, but how they relate to pathogenesis and whether these cells can serve as biomarkers of disease activity in humans deserve further exploration.

Myeloid-derived suppressor cell and regulatory T cell frequencies in canine myasthenia gravis: A pilot study

Myasthenia gravis (MG) is a T cell-dependent, B cell-mediated autoimmune disease. Little is known about its cellular pathogenesis in dogs. This study provides the first preliminary assessment of the frequency of myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs) in the peripheral blood of dogs with seropositive generalized MG. No alteration in frequency of either MDSCs or Tregs in dogs with MG was observed when compared to those in either seronegative dogs with diagnoses other than MG, or healthy dogs. A longitudinal study in three dogs with MG revealed no correlation between the relative numbers of either population and the clinical course of disease. Neither the frequency of MDSCs nor of Tregs showed a correlation with anti-AChR antibody titer in dogs with MG. These findings suggest that aberrations in the frequency of either immunosuppressive population do not occur in MG, but they need to be validated in large-scale prospective studies.

Treatment With Hydrolyzed Diet Supplemented With Prebiotics and Glycosaminoglycans Alters Lipid Metabolism in Canine Inflammatory Bowel Disease

Canine inflammatory bowel disease (IBD) is a chronic, immunologically mediated intestinal disorder, resulting from the complex interaction of genetic, environmental and immune factors. Hydrolyzed diets are used in dogs with food-responsive diarrhea (FRD) to reduce adverse responses to immunostimulatory proteins. Prebiotics (PRBs) and glycosaminoglycans (GAGs) have previously been demonstrated to show anti-inflammatory activity in the intestinal mucosa. Notably, hydrolyzed diets combined with the administration of PRBs and GAGs offer a promising approach for the treatment of canine IBD. Our aim was to investigate the effects of hydrolyzed diet and GAG+PRB co-treatment on the serum metabolomic profile of IBD dogs. Dogs with IBD randomly received either hydrolyzed diet supplemented with GAGs and PRBs (treatment 1) or hydrolyzed diet alone (treatment 2) for 10 weeks. A targeted metabolomics approach using mass spectrometry was performed to quantify changes in the serum metabolome before and after treatment and between treatment 1 and 2. Principal component analysis (PCA), partial least squares-discriminant analysis (PLS-DA), hierarchical cluster analysis (HCA) and univariate statistics were used to identify differences between the treatment groups. PCA, PLS-DA, and HCA showed a clear clustering of IBD dogs before and after hydrolyzed diet, indicating that the treatment impacted the serum metabolome. Univariate analysis revealed that most of the altered metabolites were involved in lipid metabolism. The most impacted lipid classes were components of cell membranes, including glycerophospholipids, sphingolipids, and di- and triglycerides. In addition, changes in serum metabolites after GAG+PRB co-treatment suggested a possible additional beneficial effect on the lipid metabolism in IBD dogs. In conclusion, the present study showed a significant increase in metabolites that protect gut cell membrane integrity in response to hydrolyzed diet alone or in combination with GAG+PRB co-treatment. Administration of such treatment over 70 days improved selected serum biomarkers of canine IBD, possibly indicating improved intestinal membrane integrity.

Loss of Phosphatidylinositol 3-Kinase Activity in Regulatory T Cells Leads to Neuronal Inflammation

Class I PI3K enzymes are critical for the maintenance of effective immunity. In T cells, PI3Kα and PI3Kδ are activated by the TCR and costimulatory receptors, whereas PI3Kγ is activated by G protein-coupled chemokine receptors. PI3Kδ is a key regulator of regulatory T (Treg) cell function. PI3K isoform-selective inhibitors are in development for the treatment of diseases associated with immune dysregulation, including chronic inflammatory conditions, cancer, and autoimmune diseases. Idelalisib (PI3Kδ), alpelisib (PI3Kα), duvelisib (PI3Kδ/γ), and copanlisib (pan-PI3K) have recently been approved for use in cancer treatment. Although effective, these therapies often have severe side effects associated with immune dysregulation and, in particular, loss of Treg cells. Therefore, it is important to gain a better understanding of the relative contribution of different PI3K isoforms under homeostatic and inflammatory conditions. Experimental autoimmune encephalitis is a mouse model of T cell-driven CNS inflammation, in which Treg cells play a key protective role. In this study, we show that PI3Kδ is required to maintain normal Treg cell development and phenotype under homeostatic conditions but that loss of PI3Kδ alone in Treg cells does not lead to autoimmunity. However, combined loss of PI3Kα and PI3Kδ signaling resulted in increased experimental autoimmune encephalitis disease severity. Moreover, mice lacking PI3Kα and PI3Kδ in Treg cells developed spontaneous peripheral nerve inflammation. These results show a key role for PI3K signaling in Treg cell-mediated protection against CNS inflammation.

Gene Expression Profiling of B Cell Lymphoma in Dogs Reveals Dichotomous Metabolic Signatures Distinguished by Oxidative Phosphorylation

Gene expression profiling has revealed molecular heterogeneity of diffuse large B cell lymphoma (DLBCL) in both humans and dogs. Two DLBCL subtypes based on cell of origin are generally recognized, germinal center B (GCB)-like and activated B cell (ABC)-like. A pilot study to characterize the transcriptomic phenotype of 11 dogs with multicentric BCL yielded two molecular subtypes distinguished on the basis of genes important in oxidative phosphorylation. We propose a metabolic classification of canine BCL that transcends cell of origin and shows parallels to a similar molecular phenotype in human DLBCL. We thus confirm the validity of this classification scheme across widely divergent mammalian taxa and add to the growing body of literature suggesting cellular and molecular similarities between human and canine non-Hodgkin lymphoma. Our data support a One Health approach to the study of DLBCL, including the advancement of novel therapies of relevance to both canine and human health.

Bacterial Killing Activity of Polymorphonuclear Myeloid-Derived Suppressor Cells Isolated From Tumor-Bearing Dogs

Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are implicated in the progression and outcome of a variety of pathological states, from cancer to infection. Our previous work has identified three antimicrobial peptides differentially expressed by PMN-MDSCs compared to conventional neutrophils isolated from dogs, mice, and human patients with cancer. We therefore hypothesized that PMN-MDSCs in dogs with cancer possess antimicrobial activity. In the current work, we observed that exposure of PMN-MDSCs to Gram-negative bacteria (Escherichia coli) increased the expression of reactive oxygen species by the PMN-MDSCs, indicating that they are capable of initiating an anti-microbial response. Electron microscopy revealed that the PMN-MDSCs phagocytosed Gram-negative and Gram-positive (Staphylococcus aureus) bacterial species. Lysis of bacteria within some of the PMN-MDSCs suggested bactericidal activity, which was confirmed by the recovery of significantly lower numbers of bacteria of both species following exposure to PMN-MDSCs isolated from tumor-bearing dogs. Our data therefore indicate that PMN-MDSCs isolated from dogs with cancer, in common with PMNs, have phagocytic and bactericidal activity. This nexus of immunosuppressive and antimicrobial activity reveals a hitherto unrecognized function of MDSCs.

Phenotypic characterisation of regulatory T cells in dogs reveals signature transcripts conserved in humans and mice

Regulatory T cells (Tregs) are a double-edged regulator of the immune system. Aberrations of Tregs correlate with pathogenesis of inflammatory, autoimmune and neoplastic disorders. Phenotypically and functionally distinct subsets of Tregs have been identified in humans and mice on the basis of their extensive portfolios of monoclonal antibodies (mAb) against Treg surface antigens. As an important veterinary species, dogs are increasingly recognised as an excellent model for many human diseases. However, insightful study of canine Tregs has been restrained by the limited availability of mAb. We therefore set out to characterise CD4⁺CD25^high T cells isolated ex vivo from healthy dogs and showed that they possess a regulatory phenotype, function, and transcriptomic signature that resembles those of human and murine Tregs. By launching a cross-species comparison, we unveiled a conserved transcriptomic signature of Tregs and identified that transcript hip1 may have implications in Treg function.

Randomised controlled trial of fractionated and unfractionated prednisolone regimens for dogs with immune-mediated haemolytic anaemia

METHODS

A randomised non-blinded non-inferiority trial was conducted to determine whether treatment with an unfractionated regimen of oral prednisolone was inferior to a fractionated regimen for dogs with primary immune-mediated haemolytic anaemia. Dogs received the same total daily dose of prednisolone as unfractionated (group 1, starting at 4 mg/kg orally once daily) or fractionated (group 2, starting at 2 mg/kg orally twice daily) doses. Questionnaires were administered to owners to assess adverse effects and quality of life (QoL). End points included survival to eight weeks, and changes in QoL and clinicopathological parameters over time.

RESULTS

Thirty-nine dogs were enrolled in the study, of which 5 were withdrawn and 17 were assigned to each group. The number of cases recruited was insufficient to determine whether unfractionated treatment was inferior to fractionated. Total serum bilirubin decreased more rapidly in dogs in group 2, whereas polydipsia improved more rapidly in group 1. Blood pressure and score for polyuria were higher in dogs in group 2 over time, whereas lymphocyte concentration was lower.

CONCLUSION

Administration of the same total daily dose of prednisolone as an unfractionated dose resulted in fewer adverse effects but the effect on survival could not be assessed in this study.

ACVIM consensus statement on the treatment of immune-mediated hemolytic anemia in dogs

Immune‐mediated hemolytic anemia (IMHA) causes severe anemia in dogs and is associated with considerable morbidity and mortality. Treatment with various immunosuppressive and antithrombotic drugs has been described anecdotally and in previous studies, but little consensus exists among veterinarians as to the optimal regimen to employ and maintain after diagnosis of the disease. To address this inconsistency and provide evidence‐based guidelines for treatment of IMHA in dogs, we identified and extracted data from studies published in the veterinary literature. We developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria, explanation of treatment regimens, and validity of statistical methods. In combination with our clinical experience and comparable guidelines for humans afflicted with autoimmune hemolytic anemia, we used the conclusions of this process to make a set of clinical recommendations regarding treatment of IMHA in dogs, which we refined subsequently by conducting several iterations of Delphi review. Additionally, we considered emerging treatments for IMHA in dogs and highlighted areas deserving of future research. Comments were solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted for publication. The resulting document is intended to provide clinical guidelines for management of IMHA in dogs. These guidelines should be implemented pragmatically, with consideration of animal, owner, and veterinary factors that may vary among cases.

ACVIM consensus statement on the diagnosis of immune-mediated hemolytic anemia in dogs and cats

Immune-mediated hemolytic anemia (IMHA) is an important cause of morbidity and mortality in dogs. IMHA also occurs in cats, although less commonly. IMHA is considered secondary when it can be attributed to an underlying disease, and as primary (idiopathic) if no cause is found. Eliminating diseases that cause IMHA may attenuate or stop immune-mediated erythrocyte destruction, and adverse consequences of long-term immunosuppressive treatment can be avoided. Infections, cancer, drugs, vaccines, and inflammatory processes may be underlying causes of IMHA. Evidence for these comorbidities has not been systematically evaluated, rendering evidence-based decisions difficult. We identified and extracted data from studies published in the veterinary literature and developed a novel tool for evaluation of evidence quality, using it to assess study design, diagnostic criteria for IMHA, comorbidities, and causality. Succinct evidence summary statements were written, along with screening recommendations. Statements were refined by conducting 3 iterations of Delphi review with panel and task force members. Commentary was solicited from several professional bodies to maximize clinical applicability before the recommendations were submitted. The resulting document is intended to provide clinical guidelines for diagnosis of, and underlying disease screening for, IMHA in dogs and cats. These should be implemented with consideration of animal, owner, and geographical factors.

Mycophenolic acid in patients with immune-mediated inflammatory diseases: From humans to dogs

Mycophenolic acid (MPA), a noncompetitive, selective and reversible inhibitor of inosine 5'-monophosphate dehydrogenase (IMPDH), is an immunosuppressive agent that has a long history in medicine. Mechanistically, the inhibition of IMPDH leads to the selective and eventual arrest of T- and B-lymphocyte proliferation. Mycophenolate mofetil (MMF), the first MPA-based product to receive marketing approval over two decades ago, was originally indicated for the prophylaxis of organ rejection in human transplant patients. Given its broad immunosuppressive properties and ability to selectively inhibit lymphocyte division and effector functions, the clinical utility of MPA was subsequently explored in a host of autoimmune diseases. Human clinical studies have shown MPA to be safe and effective and support its off-label administration for immune-mediated diseases such as lupus, myasthenia gravis and atopic dermatitis. MMF became generically available in the United States in 2008, and its clinical utility is increasingly being explored as a treatment option for dogs with immune-mediated diseases. This review summarizes the available literature for MPA pharmacokinetics and pharmacodynamics, and the current status of MPA as a treatment for client-owned dogs diagnosed with immune-mediated diseases.

Companion animals in comparative oncology: One Medicine in action

Comparative oncology is poised to have a far-reaching impact on both animals and human beings with cancer. The field is gaining momentum and has repeatedly proven its utility in various aspects of oncology, including study of the genetics, development, progression, immunology and therapy of cancer. Companion animals provide many advantages over both traditional rodent models and human beings for studying cancer biology and accelerating the development of novel anti-cancer therapies. In this review, several examples of the ability of companion animals with spontaneous cancers to fill a unique niche in the field of oncology are discussed. In addition, potential caveats of the use of companion animals in research are reviewed, as well as ethical considerations and efforts to standardize veterinary clinical trials.

Immunohistochemical characterization of feline lymphoplasmacytic anterior uveitis

OBJECTIVE

To characterize the immune cells present in different forms of feline anterior uveitis.

SAMPLES

Eyes were obtained from 49 cats diagnosed with chronic idiopathic lymphoplasmacytic anterior uveitis, 7 cats with feline infectious peritonitis (FIP), and 9 cats euthanized for nonocular disease.

METHODS

H&E sections were scored on the level of infiltrate in the anterior uvea. Immunohistochemistry was performed for FoxP3, CD3, and IL-17A, and positive cells were quantified in multiple images of each sample. A generalized estimating equation tested for an association between the level of inflammation and the prevalence of these cell types.

RESULTS

Cells stained positive for IL-17A in idiopathic uveitis but not in FIP samples. We found significantly fewer FoxP3⁺ and CD3⁺ cells in low-grade compared with high-grade inflammation in idiopathic uveitis or FIP samples (P values all <.005), but no difference between FIP and high-grade samples.

CONCLUSIONS

Idiopathic, but not FIP-associated, uveitis appears to have Th17 cell involvement. The numbers of FoxP3⁺ and CD3⁺ T-cells present appear directly correlated; thus, the severity of disease does not appear directly determined by the numbers of regulatory cells.

Diagnosis of anaplastic large-cell lymphoma in a dog using CD30 immunohistochemistry

Anaplastic large-cell lymphoma or null-cell lymphoma is a clinical entity reported in people, classified according to the unique appearance of large pleomorphic cells that express CD30. Null-cell lymphoma has also been described in dogs when neither CD3 nor CD79α is expressed by the tumor. We describe a case of lymphoma in the dog in which neoplastic cells did not express routine B- or T-lymphocyte markers on flow cytometry or immunohistochemistry; however, cells immunohistochemically labeled for CD30. The dog in our case died 5 mo after initial presentation, confirming a poor prognosis. Identification of further similar cases in dogs would provide additional prognostic information for this subset of lymphomas. CD30 may also serve as a potential therapeutic target in anaplastic large-cell lymphomas.

Characterization of Paroxysmal Gluten-Sensitive Dyskinesia in Border Terriers Using Serological Markers

BACKGROUND

Paroxysmal gluten-sensitive dyskinesia (PGSD) in border terriers (BTs) results from an immunologic response directed against transglutaminase (TG)2 and gliadin. Recent evidence suggests that PGSD is only one aspect of a range of possible manifestations of gluten sensitivity in the breed.

HYPOTHESIS/OBJECTIVES

Gluten sensitivity in BTs is a heterogeneous disease process with a diverse clinical spectrum; to characterize the phenotype of PGSD using TG2 and gliadin autoantibodies as diagnostic markers.

ANIMALS

One hundred twenty-eight client-owned BTs with various disorders.

METHODS

Prospective study. BTs with paroxysmal episodes and a normal interictal examination were phenotyped using footage of a representative episode and assigned to 3 groups: idiopathic epilepsy (IE), paroxysmal dyskinesia (PD), or other. Owners of each dog completed a questionnaire to obtain information regarding clinical signs. Healthy BTs formed a control group. Serum antibodies against TG2 and AGA were measured in all dogs.

RESULTS

One hundred twenty-eight BTs were enrolled; 45 with PD, 28 with IE, 35 with other conditions, and 20 controls. Three overlapping phenotypes were identified; PD, signs suggestive of gastrointestinal disease, and dermatopathy. AGA-IgG concentrations were increased in PD, compared with IE (P = 0.012), controls (P < 0.0001) and other (P = 0.018) conditions. Anti-canine TG2-IgA concentrations were increased in PD, compared with IE (P < 0.0001), controls (P < 0.0001) and other (P = 0.012) conditions. Serological markers are highly specific for PGSD but lack sensitivity.

CONCLUSIONS

PGSD appears part of a syndrome of gluten intolerance consisting of episodes of transient dyskinesia, signs suggestive of gastrointestinal disease, and dermatological hypersensitivity.

Prognostic significance of clinical presentation, induction and rescue treatment in 42 cases of canine centroblastic diffuse large B-cell multicentric lymphoma in the United Kingdom

Canine lymphoma is a heterogeneous group of diseases and many previous studies have evaluated the response of a mixed population of lymphoma cases to one specific treatment protocol. The aim of this retrospective study was to describe the outcome and prognostic factors in 42 cases of multicentric centroblastic diffuse large B-cell lymphoma treated with either a COP-type (35%) or CHOP-type (64%) induction chemotherapy. The objective response rate to induction therapy was 94%; entire dogs had a greater rate of complete vs partial remissions than neutered dogs (P = .017). Median progression-free survival for the first remission (PFS1) was 182 days; absence of anaemia at diagnosis (P = .002) and pretreatment neutrophil:lymphocyte ratio (NLR) below 9.44 (P = .015) were independently predictive of longer PFS1. Fifty-eight percent of dogs received rescue protocols with an objective response rate of 81%; 31% of dogs received further rescue protocols (up to a total of 5) and the median number of protocols administered were 2. Median overall survival (OS) was 322 days, the 1-year survival rate was 38% and the 2-year survival rate was 9%. Lymphocyte:monocyte ratio above 1.43 (P = .031), NLR below 11.44 (P = .009), the combination of induction and rescue therapy (P = .030) and the total number of doxorubicin doses used (P = .002) were independently predictive of longer OS. Use of a COP-type protocol induction compared with CHOP did not undermine OS providing doxorubicin was used as rescue therapy.

Serum anti-Müllerian hormone concentrations before and after treatment of an ovarian granulosa cell tumour in a cat

Case summary

A 15-year-old female cat was presented for investigation of progressive behavioural changes, polyuria, polydipsia and periuria. An ovarian granulosa cell tumour was identified and the cat underwent therapeutic ovariohysterectomy (OHE). The cat’s clinical signs resolved, but 6 months later it was diagnosed as having an anaplastic astrocytoma and was euthanased. Serum anti-Müllerian hormone (AMH) concentration prior to OHE was increased vs a control group of entire and neutered female cats. Following OHE, serum AMH concentration decreased to <1% of the original value.

Relevance and novel information

Serum AMH measurement may represent a novel diagnostic and monitoring tool for functional ovarian neoplasms in cats.

MicroRNAs regulate T-cell production of interleukin-9 and identify hypoxia-inducible factor-2α as an important regulator of T helper 9 and regulatory T-cell differentiation

MicroRNAs (miRNAs) regulate many aspects of helper T cell (Th) development and function. Here we found that they are required for the suppression of interleukin-9 (IL-9) expression in Th9 cells and other Th subsets. Two highly related miRNAs (miR-15b and miR-16) that we previously found to play an important role in regulatory T (Treg) cell differentiation were capable of suppressing IL-9 expression when they were over-expressed in Th9 cells. We used these miRNAs as tools to identify novel regulators of IL-9 expression and found that they could regulate the expression of Epas1, which encodes hypoxia-inducible factor (HIF)-2α. HIF proteins regulate metabolic pathway usage that is important in determining appropriate Th differentiation. The related protein, HIF-1α enhances Th17 differentiation and inhibits Treg cell differentiation. Here we found that HIF-2α was required for IL-9 expression in Th9 cells, but its expression was not sufficient in other Th subsets. Furthermore, HIF-2α suppressed Treg cell differentiation like HIF-1α, demonstrating both similar and distinct roles of the HIF proteins in Th differentiation and adding a further dimension to their function. Ironically, even though miR-15b and miR-16 suppressed HIF-2α expression in Treg cells, inhibiting their function in Treg cells did not lead to an increase in IL-9 expression. Therefore, the physiologically relevant miRNAs that regulate IL-9 expression in Treg cells and other subsets remain unknown. Nevertheless, the analysis of miR-15b and miR-16 function led to the discovery of the importance of HIF-2α so this work demonstrated the utility of studying miRNA function to identify novel regulatory pathways in helper T-cell development.

Characterisation of the Immunophenotype of Dogs with Primary Immune-Mediated Haemolytic Anaemia

Background

Immune-mediated haemolytic anaemia (IMHA) is reported to be the most common autoimmune disease of dogs, resulting in significant morbidity and mortality in affected animals. Haemolysis is caused by the action of autoantibodies, but the immunological changes that result in their production have not been elucidated.

Aims

To investigate the frequency of regulatory T cells (Tregs) and other lymphocyte subsets and to measure serum concentrations of cytokines and peripheral blood mononuclear cell expression of cytokine genes in dogs with IMHA, healthy dogs and dogs with inflammatory diseases.

Animals

19 dogs with primary IMHA, 22 dogs with inflammatory diseases and 32 healthy control dogs.

Methods

Residual EDTA-anti-coagulated blood samples were stained with fluorophore-conjugated monoclonal antibodies and analysed by flow cytometry to identify Tregs and other lymphocyte subsets. Total RNA was also extracted from peripheral blood mononuclear cells to investigate cytokine gene expression, and concentrations of serum cytokines (interleukins 2, 6 10, CXCL-8 and tumour necrosis factor α) were measured using enhanced chemiluminescent assays. Principal component analysis was used to investigate latent variables that might explain variability in the entire dataset.

Results

There was no difference in the frequency or absolute numbers of Tregs among groups, nor in the proportions of other lymphocyte subsets. The concentrations of pro-inflammatory cytokines were greater in dogs with IMHA compared to healthy controls, but the concentration of IL-10 and the expression of cytokine genes did not differ between groups. Principal component analysis identified four components that explained the majority of the variability in the dataset, which seemed to correspond to different aspects of the immune response.

Conclusions

The immunophenotype of dogs with IMHA differed from that of dogs with inflammatory diseases and from healthy control dogs; some of these changes could suggest abnormalities in peripheral tolerance that permit development of autoimmune disease. The frequency of Tregs did not differ between groups, suggesting that deficiency in the number of these cells is not responsible for development of IMHA.

Retroviral Transduction of Helper T Cells as a Genetic Approach to Study Mechanisms Controlling their Differentiation and Function

Helper T cell development and function must be tightly regulated to induce an appropriate immune response that eliminates specific pathogens yet prevents autoimmunity. Many approaches involving different model organisms have been utilized to understand the mechanisms controlling helper T cell development and function. However, studies using mouse models have proven to be highly informative due to the availability of genetic, cellular, and biochemical systems. One genetic approach in mice used by many labs involves retroviral transduction of primary helper T cells. This is a powerful approach due to its relative ease, making it accessible to almost any laboratory with basic skills in molecular biology and immunology. Therefore, multiple genes in wild type or mutant forms can readily be tested for function in helper T cells to understand their importance and mechanisms of action. We have optimized this approach and describe here the protocols for production of high titer retroviruses, isolation of primary murine helper T cells, and their transduction by retroviruses and differentiation toward the different helper subsets. Finally, the use of this approach is described in uncovering mechanisms utilized by microRNAs (miRNAs) to regulate pathways controlling helper T cell development and function.

Quantitative Expression and Co-Localization of Wnt Signalling Related Proteins in Feline Squamous Cell Carcinoma

Feline oral squamous cell carcinoma (FOSCC) is an aggressive neoplasm in cats. Little is known about the possible molecular mechanisms that may be involved in the initiation, maintenance and progression of FOSCC. Wnt signalling is critical in development and disease, including many mammalian cancers. In this study, we have investigated the expression of Wnt signalling related proteins using quantitative immunohistochemical techniques on tissue arrays. We constructed tissue arrays with 58 individual replicate tissue samples. We tested for the expression of four key Wnt/ß-catenin transcription targets, namely Cyclin D1 (CCND1 or CD1), FRA1, c-Myc and MMP7. All antibodies showed cross reactivity in feline tissue except MMP7. Quantitative immunohistochemical analysis of single proteins (expressed as area fraction / amount of tissue for normal vs tumor, mean ± SE) showed that the expression of CD1 (3.9 ± 0.5 vs 12.2 ± 0.9), FRA1 (5.5 ± 0.6 vs 16.8 ± 1.1) and c-Myc (5.4 ± 0.5 vs 12.5 ± 0.9) was increased in FOSCC tissue by 2.3 to 3 fold compared to normal controls (p<0.0001). By using a multilabel, quantitative fluorophore technique we further investigated if the co-localization of these proteins (all transcription factors) with each other and in the nucleus (stained with 4',6-diamidino-2-phenylindole, DAPI) was altered in FOSCC compared to normal tissue. The global intersection coefficients, a measure of the proximity of two fluorophore labeled entities, showed that there was a significant change (p < 0.01) in the co-localization for all permutations (e.g. CD1/FRA1 etc), except for the nuclear localization of CD1. Our results show that putative targets of Wnt signalling transcription are up-regulated in FOSCC with alterations in the co-localization of these proteins and could serve as a useful marker for the disease.

European canine lymphoma network consensus recommendations for reporting flow cytometry in canine hematopoietic neoplasms

BACKGROUND

Flow cytometry (FC) is assuming increasing importance in diagnosis in veterinary oncology. The European Canine Lymphoma Network (ECLN) is an international cooperation of different institutions working on canine lymphoma diagnosis and therapy. The ECLN panel of experts on FC has defined the issue of reporting FC on canine lymphoma and leukemia as their first hot topic, since a standardized report that includes all the important information is still lacking in veterinary medicine.

METHODS

The flow cytometry panel of the ECLN started a consensus initiative using the Delphi approach. Clinicians were considered the main target of FC reports. A panel of experts in FC was interrogated about the important information needed from a report.

RESULTS

Using the feedback from clinicians and subsequent discussion, a list of information to be included in the report was made, with four different levels of recommendation. The final report should include both a quantitative part and a qualitative or descriptive part with interpretation of the salient results. Other items discussed included the necessity of reporting data regarding the quality of samples, use of absolute numbers of positive cells, cutoff values, the intensity of fluorescence, and possible aberrant patterns of antigen expression useful from a clinical point of view.

CONCLUSION

The consensus initiative is a first step toward standardization of diagnostic approach to canine hematopoietic neoplasms among different institutions and countries. This harmonization will improve communication and patient care and also facilitate the multicenter studies necessary to further our knowledge of canine hematopoietic neoplasms. © 2016 International Clinical Cytometry Society.

Complications of Percutaneous Endoscopic Gastrostomy in Dogs and Cats Receiving Corticosteroid Treatment

BACKGROUND

Corticosteroid treatment is commonly required in veterinary patients for treatment of inflammatory, immune-mediated, neurologic, and neoplastic diseases, which also may require assisted enteral nutrition via percutaneous endoscopic gastrostomy (PEG).

OBJECTIVE

To evaluate complications associated with PEG use in dogs and cats receiving corticosteroid treatment.

ANIMALS

Forty-two animals were included in the study: 12 dogs and 2 cats in the steroid group and 26 dogs and 2 cats in the control group.

METHODS

Medical records, between January 2006 and March 2015, were reviewed. Patients were included if the PEG tube was in use for at least 24 hours and if complete medical records were available. Patients were assigned to the control group if they were not treated with corticosteroids during PEG use or to the steroid group if they had received corticosteroids during PEG tube use. Complications were classified as minor, moderate, and major in severity. Maximum severity complication rate was compared between groups.

RESULTS

The general prevalence of complications was found to be similar between groups (P = .306), but in the steroid group, 43% of the cases developed a major severity complication compared with 18% of the control group (P = .054).

CONCLUSION AND CLINICAL IMPORTANCE

Owners of dogs and cats receiving corticosteroids, in which PEG is planned, should be counseled about possible complications beyond those associated with PEG tube usage alone.

Missed, Not Missing: Phylogenomic Evidence for the Existence of Avian FoxP3

The Forkhead box transcription factor FoxP3 is pivotal to the development and function of regulatory T cells (Tregs), which make a major contribution to peripheral tolerance. FoxP3 is believed to perform a regulatory role in all the vertebrate species in which it has been detected. The prevailing view is that FoxP3 is absent in birds and that avian Tregs rely on alternative developmental and suppressive pathways. Prompted by the automated annotation of foxp3 in the ground tit (Parus humilis) genome, we have questioned this assumption. Our analysis of all available avian genomes has revealed that the foxp3 locus is missing, incomplete or of poor quality in the relevant genomic assemblies for nearly all avian species. Nevertheless, in two species, the peregrine falcon (Falco peregrinus) and the saker falcon (F. cherrug), there is compelling evidence for the existence of exons showing synteny with foxp3 in the ground tit. A broader phylogenomic analysis has shown that FoxP3 sequences from these three species are similar to crocodilian sequences, the closest living relatives of birds. In both birds and crocodilians, we have also identified a highly proline-enriched region at the N terminus of FoxP3, a region previously identified only in mammals.

Serum Biochemical Phenotypes in the Domestic Dog

The serum or plasma biochemical profile is essential in the diagnosis and monitoring of systemic disease in veterinary medicine, but current reference intervals typically take no account of breed-specific differences. Breed-specific hematological phenotypes have been documented in the domestic dog, but little has been published on serum biochemical phenotypes in this species. Serum biochemical profiles of dogs in which all measurements fell within the existing reference intervals were retrieved from a large veterinary database. Serum biochemical profiles from 3045 dogs were retrieved, of which 1495 had an accompanying normal glucose concentration. Sixty pure breeds plus a mixed breed control group were represented by at least 10 individuals. All analytes, except for sodium, chloride and glucose, showed variation with age. Total protein, globulin, potassium, chloride, creatinine, cholesterol, total bilirubin, ALT, CK, amylase, and lipase varied between sexes. Neutering status significantly impacted all analytes except albumin, sodium, calcium, urea, and glucose. Principal component analysis of serum biochemical data revealed 36 pure breeds with distinctive phenotypes. Furthermore, comparative analysis identified 23 breeds with significant differences from the mixed breed group in all biochemical analytes except urea and glucose. Eighteen breeds were identified by both principal component and comparative analysis. Tentative reference intervals were generated for breeds with a distinctive phenotype identified by comparative analysis and represented by at least 120 individuals. This is the first large-scale analysis of breed-specific serum biochemical phenotypes in the domestic dog and highlights potential genetic components of biochemical traits in this species.

Cytological Findings of 140 Bile Samples from Dogs and Cats and Associated Clinical Pathological Data

Background

Cholecystocentesis can be part of the diagnostic workup of hepatobiliary disease in small animals, but literature on cytological evaluation of bile is scant.

Objectives

To determine the diagnostic utility of cytological assessment of bile aspirates.

Animals

Fifty‐six and 78 client‐owned dogs and cats, respectively, with bile collected by cholecystocentesis and submitted to our diagnostic laboratory between 1999 and 2014.

Methods

Retrospective study describing cytological findings of bile, concurrent bacterial culture results, hematological and serum biochemical data, gallbladder biopsy results, as well as final diagnosis and complications after cholecystocentesis.

Results

Infectious agents were found in 30% of canine and 22% of feline bile aspirates, and inflammation in 5% and 19% respectively. Presence of microorganisms was more often detected on cytological examination (24%) than by culture (21%). The most common bacterial isolates were Escherichia coli and Enterococcus spp., isolated from 14.8% and 6.7% of cultured samples respectively. Only increased canine pancreatic lipase immunoreactivity concentration (cPLI) was significantly associated with the presence of microorganisms, inflammatory cells, or both in bile. Clinically relevant complications of cholecystocentesis occurred in 2 dogs. The majority of the animals undergoing cholecystocentesis suffered from hepatic, pancreatic, gastrointestinal disease, or a combination thereof.

Conclusions and Clinical Importance

Cytological examination of bile is inexpensive and straightforward, and yields diagnostically relevant information that precedes and complements bacterial culture.

MicroRNA-15b/16 Enhances the Induction of Regulatory T Cells by Regulating the Expression of Rictor and mTOR

CD4(+) regulatory T cells (Tregs) are essential for controlling immune responses and preventing autoimmunity. Their development requires regulation of gene expression by microRNAs (miRNAs). To understand miRNA function in Treg development, we searched for important miRNAs and their relevant target genes. Of the more abundantly expressed miRNAs in Tregs, only miR-15b/16, miR-24, and miR-29a impacted the production of in vitro-induced Tregs (iTregs) in overexpression and blocking experiments. miRNA mimics for these significantly enhanced the induction of iTregs in Dicer(-/-) CD4(+) T cells. Furthermore, the overexpression of miR-15b/16 in conventional CD4(+) T cells adoptively transferred into Rag2(-/-) mice increased the in vivo development of peripheral Tregs and diminished the severity of autoimmune colitis. In searching for targets of miR-15b/16, we observed that the mammalian target of rapamycin (mTOR) signaling pathway was enhanced in Dicer(-/-) CD4(+) T cells, and its pharmacological inhibition restored induction of iTregs. Suppression of mTOR signaling is essential for induction of iTregs from naive CD4(+) T cells, and the mTORC2 component, Rictor, contained a functional target site for miR-15b/16. Rictor was more abundantly expressed in Dicer(-/-) T cells as was mTOR, and their expression was downregulated by the overexpression of miR-15b/16. This led to a reduction in mTOR signaling, as measured by phosphorylation of the downstream target, ribosomal protein S6. Finally, knockdown of Rictor by small interfering RNAs enhanced Treg induction in Dicer(-/-) CD4(+) T cells. Therefore, an important mechanism of miRNA regulation of Treg development is through regulation of the mTOR signaling pathway.

The Clinical and Serological Effect of a Gluten-Free Diet in Border Terriers with Epileptoid Cramping Syndrome

Background

Canine epileptoid cramping syndrome (CECS) is a paroxysmal movement disorder of Border Terriers (BTs). These dogs might respond to a gluten‐free diet.

Objectives

The objective of this study was to examine the clinical and serological effect of a gluten‐free diet in BTs with CECS.

Animals

Six client‐owned BTs with clinically confirmed CECS.

Methods

Dogs were prospectively recruited that had at least a 6‐month history of CECS based on the observed phenomenology (using video) and had exhibited at least 2 separate episodes on different days. Dogs were tested for anti‐transglutaminase 2 (TG2 IgA) and anti‐gliadin (AGA IgG) antibodies in the serum at presentation, and 3, 6, and 9 months after the introduction of a gluten‐free diet. Duodenal biopsies were performed in 1 dog.

Results

Serum TG2 IgA titers were increased in 6/6 BTs (P = .006) and AGA IgG titers were increased in 5/6 BTs at presentation compared to those of controls (P = .018). After 9 months, there was clinical and serological improvement in all BTs with CECS strictly adhering to a gluten‐free diet (5/5). One dog had persistently increased antibody titers. This dog scavenged horse manure. On the strict introduction of a gluten‐free diet this dog also had an improved clinical and serological response. The diet‐associated improvement was reversible in 2 dogs on completion of the study, both of which suffered a relapse of CECS on the re‐introduction of gluten.

Conclusions

Canine epileptoid cramping syndrome in BTs is a gluten‐sensitive movement disorder triggered and perpetuated by gluten and thus responsive to a gluten‐free diet.

Histologic and clinical features of primary and secondary vasculitis

Inflammation of the blood vessel wall has been reported infrequently in dogs, and it may occur without apparent cause (primary vasculitis) or as a pathologic reaction to a range of initiating insults (secondary vasculitis). The aims of our study were to report histologic, clinical, and survival data from a large series of cases with primary and secondary vasculitis, and to compare the clinical parameters and outcome data between groups. Clinical data was collected retrospectively from the medical records of 42 client-owned dogs with a histologic diagnosis of primary or secondary vasculitis, and follow-up information was obtained. Cases were grouped according to clinical and histologic descriptors, and biochemical, hematologic, and survival data was compared between groups. Several forms of primary vasculitis were observed, and vascular inflammation was observed in conjunction with numerous other diseases. Female dogs were more likely to develop primary vasculitis, and serum globulin concentration was greater in dogs with primary vasculitis compared to those with underlying disease. All dogs with primary vasculitis of the central nervous system died or were euthanized shortly after presentation, but other forms of primary vasculitis could be managed effectively. In conclusion, presentation of clinical cases in this series was variable, and there did not appear to be well-defined vasculitic syndromes as described in people.

A prospective, randomized, blinded, placebo-controlled pilot study on the effect of Enterococcus faecium on clinical activity and intestinal gene expression in canine food-responsive chronic enteropathy

Background

Canine chronic enteropathies (CE) are believed to be caused by an aberrant immune response towards the intestinal microbiome. Administration of probiotics can alleviate colitis in people. In vitro effects of the probiotic Enterococcus faecium NCIMB 10415 E1707 (EF) previously have been evaluated using canine cells (e.g., whole blood, intestinal biopsies), but data on in vivo efficacy are lacking.

Hypothesis/Objectives

Administration of EF to dogs with food‐responsive CE will improve clinical outcome and decrease the intestinal inflammatory profile.

Animals

Dogs diagnosed with CE were prospectively recruited to receive a hydrolyzed elimination diet plus either a synbiotic product containing EF or placebo for 6 weeks. Both veterinary staff and owners were blinded to the treatment.

Methods

Clinical severity index (CCECAI), clinicopathological data and gene expression using intestinal biopsies (TLR2/4/5/9, IL‐17A, IL‐22, IL‐23p19, RORC, IL‐2, IL‐12p35, TNFα, IL‐4, IFNy, IL‐10, TGFβ, IL‐1β, IL‐18, NLRP3, casp‐1, TFF1, TFF3 and PPARy) before and after 6 weeks of treatment were analyzed using linear mixed modeling.

Results

Of the 45 cases recruited, 12 finished the clinical trial. Seven received the synbiotic and 5 the placebo product. There was no difference between groups or treatments regarding clinical efficacy, histology scores or expression of any of the investigated genes.

Conclusions and clinical importance

Standard dietary treatment induced rapid clinical response in all cases. Because the study was underpowered, it was not possible to determine whether or not EF had an additional effect within the time period of 6 weeks.

Dissecting the regulatory microenvironment of a large animal model of non-Hodgkin lymphoma: evidence of a negative prognostic impact of FOXP3+ T cells in canine B cell lymphoma

The cancer microenvironment plays a pivotal role in oncogenesis, containing a number of regulatory cells that attenuate the anti-neoplastic immune response. While the negative prognostic impact of regulatory T cells (Tregs) in the context of most solid tissue tumors is well established, their role in lymphoid malignancies remains unclear. T cells expressing FOXP3 and Helios were documented in the fine needle aspirates of affected lymph nodes of dogs with spontaneous multicentric B cell lymphoma (BCL), proposed to be a model for human non-Hodgkin lymphoma. Multivariable analysis revealed that the frequency of lymph node FOXP3⁺ T cells was an independent negative prognostic factor, impacting both progression-free survival (hazard ratio 1.10; p = 0.01) and overall survival (hazard ratio 1.61; p = 0.01) when comparing dogs showing higher than the median FOXP3 expression with those showing the median value of FOXP3 expression or less. Taken together, these data suggest the existence of a population of Tregs operational in canine multicentric BCL that resembles thymic Tregs, which we speculate are co-opted by the tumor from the periphery. We suggest that canine multicentric BCL represents a robust large animal model of human diffuse large BCL, showing clinical, cytological and immunophenotypic similarities with the disease in man, allowing comparative studies of immunoregulatory mechanisms.

Food-specific serum IgE and IgG reactivity in dogs with and without skin disease: lack of correlation between laboratories

BACKGROUND

Despite conflicting data on their utility and no reports on interlaboratory reproducibility, serum food-specific antibodies are commonly assayed in first-opinion canine practice.

HYPOTHESIS/OBJECTIVES

To determine both the variability of test results between two laboratories and the frequencies and magnitudes of food reactivity in dogs of different disease status.

ANIMALS

Sera were obtained from eight dogs with cutaneous adverse food reaction (Group A), 22 with nonfood-induced atopic dermatitis (Group B), 30 with an allergic/inflammatory phenotype (Group C), 12 with miscellaneous skin diseases (Group D) and nine healthy dogs (Group E).

METHODS

Paired sera were submitted to two laboratories (A and B) for assays of food-specific IgE and IgG antibodies.

RESULTS

Numbers of positive IgE and IgG tests determined by each laboratory in Groups A, B, D and E were comparable (Group C not included). Significant differences in the magnitude of IgE reactivity between groups for each allergen were seen only for lamb (Laboratory A, P = 0.003); lamb reactivity in Group D exceeded Group E (P = 0.004) but was comparable between all other groups. Agreement (kappa statistic) between the two laboratories' tests was 'moderate' for one antigen (potato IgE), 'fair' for four (corn IgE, rice IgE and IgG and soya bean IgG), 'slight' for eight (six IgE and two IgG) and 'less than chance' for the remaining six antigens (three IgE and three IgG).

CONCLUSIONS AND CLINICAL IMPORTANCE

These laboratories' tests appear to have dubious predictive clinical utility because they neither correlate nor distinguish between dogs of different disease status.

Reduced regulatory T cell diversity in NOD mice is linked to early events in the thymus

The thymic natural regulatory T cell (Treg) compartment of NOD mice is unusual in having reduced TCR diversity despite normal cellularity. In this study, we show that this phenotype is attributable to perturbations in early and late stages of thymocyte development and is controlled, at least in part, by the NOD Idd9 region on chromosome 4. Progression from double negative 1 to double negative 2 stage thymocytes in NOD mice is inefficient; however, this defect is compensated by increased proliferation of natural Tregs (nTregs) within the single positive CD4 thymocyte compartment, accounting for recovery of cellularity accompanied by loss of TCR diversity. This region also underlies the known attenuation of ERK-MAPK signaling, which may preferentially disadvantage nTreg selection. Interestingly, the same genetic region also regulates the rate of thymic involution that is accelerated in NOD mice. These findings highlight further complexity in the control of nTreg repertoire diversity.

Sialoadhesin ligand expression identifies a subset of CD4+Foxp3- T cells with a distinct activation and glycosylation profile

Sialoadhesin (Sn) is a sialic acid-binding Ig-like lectin expressed selectively on macrophage subsets. In a model of experimental autoimmune encephalomyelitis, Sn interacted with sialylated ligands expressed selectively on CD4(+)Foxp3(+) regulatory T cells (Tregs) and inhibited their proliferation. In this study, we examined the induction of Sn ligands (SnL) on all splenic CD4(+) T cells following in vitro activation. Most CD4(+) Tregs strongly upregulated SnL, whereas only a small subset of ~20% CD4(+)Foxp3(-) T cells (effector T cells [Teffs]) upregulated SnL. SnL(+) Teffs displayed higher levels of activation markers CD25 and CD69, exhibited increased proliferation, and produced higher amounts of IL-2 and IFN-γ than corresponding SnL(-) Teffs. Coculture of activated Teffs with Sn(+) macrophages or Sn(+) Chinese hamster ovary cells resulted in increased cell death, suggesting a regulatory role for Sn-SnL interactions. The key importance of α2,3-sialylation in SnL expression was demonstrated by increased binding of α2,3-linkage-specific Maackia amurensis lectin, increased expression of α2,3-sialyltransferase ST3GalVI, and loss of SnL following treatment with an α2,3-linkage-specific sialidase. The induction of SnL on activated CD4(+) T cells was dependent on N-glycan rather than O-glycan biosynthesis and independent of the mucin-like molecules CD43 and P-selectin glycoprotein ligand-1, previously implicated in Sn interactions. Induction of ligands on CD4(+)Foxp3(-) Teffs was also observed in vivo using the New Zealand Black × New Zealand White F1 murine model of spontaneous lupus and SnL levels on Teffs correlated strongly with the degree of proteinuria. Collectively, these data indicate that SnL is a novel marker of activated CD4(+) Teffs that are implicated in the pathogenesis of autoimmune diseases.

Mesenchymal stromal cells and regulatory T cells: the Yin and Yang of peripheral tolerance?

In recent years, mesenchymal stromal cells (MSCs) and regulatory T cells (Tregs) have both garnered significant interest from immunologists worldwide, not least because of the potential application of both cell types in the treatment of many chronic inflammatory and autoimmune diseases. Although both MSCs and Tregs can be considered immunosuppressive in their own right, the induction of Tregs by activated MSCs is now a well-publicised phenomenon; however, only recently have the mechanisms involved in this induction started to become clear. Indeed, it is becoming increasingly apparent that there exists a complex interplay between the two lineages leading to this potent inhibition of the host immune response. Cell contact, soluble mediators-including prostaglandin E(2) and transforming growth factor β-and indirect induction via manipulation of other antigen-presenting cells all appear to have vital roles in the interactions between MSCs and Tregs. Much still remains to be discovered before we have a full understanding of this important aspect of the immune response, but there have already been a multitude of clinical trials suggesting that MSC/Treg therapies could offer significant benefits in the treatment of both autoimmune disease and graft versus host disease. Although these therapies are still in their infancy, the synergy between MSCs and Tregs will undoubtedly yield future breakthroughs in the treatment of many debilitating conditions and usher in a new wave of targeted, cell-based therapeutics.

Does the PI3K pathway promote or antagonize regulatory T cell development and function?

Regulatory T cells (Tregs) prevent autoimmunity and inflammation by suppressing the activation of other T cells and antigen presenting cells. The role of phosphoinositide 3-kinase (PI3K) signaling in Treg is controversial. Some studies suggest that inhibition of the PI3K pathway is essential for the development of Tregs whereas other studies have shown reduced Treg numbers and function when PI3K activity is suppressed. Here we attempt to reconcile the different studies that have explored PI3K and the downstream effectors Akt, Foxo, and mTOR in regulatory T cell development and function and discuss the implications for health and therapeutic intervention.

Pten loss in CD4 T cells enhances their helper function but does not lead to autoimmunity or lymphoma

PTEN, one of the most commonly mutated or lost tumor suppressors in human cancers, antagonizes signaling by the PI3K pathway. Mice with thymocyte-specific deletion of Pten rapidly develop peripheral lymphomas and autoimmunity, which may be caused by failed negative selection of thymocytes or from dysregulation of postthymic T cells. We induced conditional deletion of Pten from CD4 Th cells using a Cre knocked into the Tnfrsf4 (OX40) locus to generate OX40(Cre)Pten(f) mice. Pten-deficient Th cells proliferated more and produced greater concentrations of cytokines. The OX40(Cre)Pten(f) mice had a general increase in the number of lymphocytes in the lymph nodes, but not in the spleen. When transferred into wild-type (WT) mice, Pten-deficient Th cells enhanced anti-Listeria responses and the clearance of tumors under conditions in which WT T cells had no effect. Moreover, inflammatory responses were exaggerated and resolved later in OX40(Cre)Pten(f) mice than in WT mice. However, in contrast with models of thymocyte-specific Pten deletion, lymphomas and autoimmunity were not observed, even in older OX40(Cre)Pten(f) mice. Hence loss of Pten enhances Th cell function without obvious deleterious effects.

The immunopathology of sepsis: pathogen recognition, systemic inflammation, the compensatory anti-inflammatory response, and regulatory T cells

Sepsis, the systemic inflammatory response to infection, represents the major cause of death in critically ill veterinary patients. Whereas important advances in our understanding of the pathophysiology of this syndrome have been made, much remains to be elucidated. There is general agreement on the key interaction between pathogen‐associated molecular patterns and cells of the innate immune system, and the amplification of the host response generated by pro‐inflammatory cytokines. More recently, the concept of immunoparalysis in sepsis has also been advanced, together with an increasing recognition of the interplay between regulatory T cells and the innate immune response. However, the heterogeneous nature of this syndrome and the difficulty of modeling it in vitro or in vivo has both frustrated the advancement of new therapies and emphasized the continuing importance of patient‐based clinical research in this area of human and veterinary medicine.