Antigen specificity in canine autoimmune haemolytic anaemia

RNA sequencing of whole blood in dogs with primary immune-mediated hemolytic anemia (IMHA) reveals novel insights into disease pathogenesis

Immune-mediated hemolytic anemia (IMHA) is a life-threatening autoimmune disorder characterized by a self-mediated attack on circulating red blood cells. The disease occurs naturally in both dogs and humans, but is significantly more prevalent in dogs. Because of its shared features across species, dogs offer a naturally occurring model for studying IMHA in people. In this study, we used RNA sequencing of whole blood from treatment-naïve dogs to study transcriptome-wide changes in gene expression in newly diagnosed animals compared to healthy controls. We found many overexpressed genes in pathways related to neutrophil function, coagulation, and hematopoiesis. In particular, the most highly overexpressed gene in cases was a phospholipase scramblase, which mediates the externalization of phosphatidylserine from the inner to the outer leaflet of cell membranes. This family of genes has been shown to be critically important for programmed cell death of erythrocytes as well as the initiation of the clotting cascade. Unexpectedly, we found marked underexpression of many genes related to lymphocyte function. We also identified groups of genes that are highly associated with the inflammatory response and red blood cell regeneration in affected dogs. We did not find any genes that distinguished dogs that lived vs. those that died at 30 days following diagnosis, nor did we find any relevant genomic signatures of microbial organisms in the blood of affected animals. Future studies are warranted to validate these findings and assess their implication in developing novel therapeutic approaches for dogs and humans with IMHA.

Clinical, hemato-biochemical alterations and oxidant-antioxidant biomarkers in Babesia-infected calves

Babesia is one of the main causes of anemia in cattle, a lot of elucidations have been suggested to explain its pathogenesis. This study was designed to investigate clinical, hemato-biochemical and oxidant/antioxidant status and its relation with the resultant anemia in Babesia-infected calves. Seventeen (17) native breed calves were involved in this study, clinical signs and microscopic findings were recorded, also blood samples were taken to investigate hematologic changes, serum biochemical variations and oxidative stress biomarkers. The most commonly observed clinical signs were fever, emaciation, depression, icterus and hemoglobinuria. Significant reduction in PCV, HB, RBCs, MCHC, Total protein, and albumin along with significant increase in MCV, WBCs, monocytes and BUN were the most consistent hemato-biochemical changes. Oxidant/antioxidant and trace mineral assessment showed significant reduction in Superoxide dismutase “SOD”, Glutathione peroxidase “GPx”, Zn, Cu along with significant increase in malondialdehyde (MDA) activities. In the current investigation, oxidant/antioxidant imbalance along with the synchronized alterations in antioxidant trace minerals was detected in Babesia-infected calves. These findings support notion that Babesia infection associated with oxidative stress and this process may be linked to the resultant anemia.

Evaluation of a DLA-79 allele associated with multiple immune-mediated diseases in dogs

Immune-mediated diseases are common and life-threatening disorders in dogs. Many canine immune-mediated diseases have strong breed predispositions and are believed to be inherited. However, the genetic mutations that cause these diseases are mostly unknown. As many immune-mediated diseases in humans share polymorphisms among a common set of genes, we conducted a candidate gene study of 15 of these genes across four immune-mediated diseases (immune-mediated hemolytic anemia, immune-mediated thrombocytopenia, immune-mediated polyarthritis (IMPA), and atopic dermatitis) in 195 affected and 206 unaffected dogs to assess whether causative or predictive polymorphisms might exist in similar genes in dogs. We demonstrate a strong association (Fisher's exact p = 0.0004 for allelic association, p = 0.0035 for genotypic association) between two polymorphic positions (10 bp apart) in exon 2 of one allele in DLA-79, DLA-79*001:02, and multiple immune-mediated diseases. The frequency of this allele was significantly higher in dogs with immune-mediated disease than in control dogs (0.21 vs. 0.12) and ranged from 0.28 in dogs with IMPA to 0.15 in dogs with atopic dermatitis. This allele has two non-synonymous substitutions (compared with the reference allele, DLA-79*001:01), resulting in F33L and N37D amino acid changes. These mutations occur in the peptide-binding pocket of the protein, and based upon our computational modeling studies, are likely to affect critical interactions with the peptide N-terminus. Further studies are warranted to confirm these findings more broadly and to determine the specific mechanism by which the identified variants alter canine immune system function.

Analysis of DLA-DQB1 and polymorphisms in CTLA4 in Cocker spaniels affected with immune-mediated haemolytic anaemia

BACKGROUND

Cocker spaniels are predisposed to immune-mediated haemolytic anaemia (IMHA), suggesting that genetic factors influence disease susceptibility. Dog leukocyte antigen (DLA) class II genes encode major histocompatibility complex (MHC) molecules that are involved in antigen presentation to CD4(+) T cells. Several DLA haplotypes have been associated with autoimmune disease, including IMHA, in dogs, and breed specific differences have been identified. Cytotoxic T lymphocyte antigen 4 (CTLA4) is a critical molecule involved in the regulation of T-cell responses. Single nucleotide polymorphisms (SNPs) in the CTLA4 promoter have been shown to be associated with several autoimmune diseases in humans and more recently with diabetes mellitus and hypoadrenocorticism in dogs. The aim of the present study was to investigate whether DLA-DQB1 alleles or CTLA4 promoter variability are associated with risk of IMHA in Cocker spaniels.

RESULTS

There were a restricted number of DLA-DQB1 alleles identified, with a high prevalence of DLA-DQB1*007:01 in both groups. A high prevalence of DLA-DQB1 homozygosity was identified, although there was no significant difference between IMHA cases and controls. CTLA4 promoter haplotype diversity was limited in Cocker spaniels, with all dogs expressing at least one copy of haplotype 8. There was no significant difference comparing haplotypes in the IMHA affected group versus control group (p = 0.23). Homozygosity for haplotype 8 was common in Cocker spaniels with IMHA (27/29; 93 %) and in controls (52/63; 83 %), with no statistically significant difference in prevalence between the two groups (p = 0.22).

CONCLUSIONS

DLA-DQB1 allele and CTLA4 promoter haplotype were not found to be significantly associated with IMHA in Cocker spaniels. Homozygosity for DLA-DQB1*007:01 and the presence of CTLA4 haplotype 8 in Cocker spaniels might increase overall susceptibility to IMHA in this breed, with other genetic and environmental factors involved in disease expression and progression.

Clinical, Hematologic, and Molecular Findings in Naturally Occurring Babesia canis vogeli in Egyptian Dogs

Background. Canine babesiosis is a clinically important hemoprotozoan parasite affecting dogs. The goal of this present study was to determine the clinical symptoms and to establish its hematological and microscopic detection and compare it with the PCR findings attained from dogs infected with Babesia canis vogeli. Methodology/Principal Findings. 13-PCR confirmed Babesia-infected dogs were examined; seminested PCR was used to discover the precise type of Babesia and Babesia canis vogeli was the only subspecies detected. The most consistent clinical signs were elevated rectal temperature and a pale mucous membrane. Thrombocytopenia, monocytosis, and lymphocytosis, along with a significant reduction in red cell parameters, were the most commonly recorded hematologic alterations. Microscopic examination revealed the presence of typical large merozoites and trophozoites of B. canis in the ratio 76.92%. Conclusions/Significance. The presumptive diagnosis of canine babesiosis should be based on a fever and anemia, while thrombocytopenia is considered the hallmark of the disease; microscopic examination may not be very revealing in the detection at low parasitemia, but it remains the most rapid confirmatory method. Seminested PCR turned out to be a sensitive and accurate method for diagnosis; during the process of differentiation between Babesia subspecies, only B. canis subsp. vogeli was detected.

Comparative analysis of canine monocyte- and bone-marrow-derived dendritic cells

Dendritic cells (DC) represent a heterogeneous cell family of major importance for innate immune responses against pathogens and antigen presentation during infection, cancer, allergy and autoimmunity. The aim of the present study was to characterize canine DC generated in vitro with respect to their phenotype, responsiveness to toll-like receptor (TLR) ligands and T-cell stimulatory capacity. DC were derived from monocytes (MoDC) and from bone marrow hematopoietic cells cultured with either Flt3-ligand (FL-BMDC) or with GM-CSF (GM-BMDC). All three methods generated cells with typical DC morphology that expressed CD1c, CD11c and CD14, similar to macrophages. However, CD40 was only found on DC, CD206 on MΦ and BMDC, but not on monocytes and MoDC. CD1c was not found on monocytes but on all in vitro differentiated cells. FL-BMDC and GM-BMDC were partially positive for CD4 and CD8. CD45RA was expressed on a subset of FL-BMDC but not on MoDC and GM-BMDC. MoDC and FL-DC responded well to TLR ligands including poly-IC (TLR2), Pam3Cys (TLR3), LPS (TLR4) and imiquimod (TLR7) by up-regulating MHC II and CD86. The generated DC and MΦ showed a stimulatory capacity for lymphocytes, which increased upon maturation with LPS. Taken together, our results are the basis for further characterization of canine DC subsets with respect to their role in inflammation and immune responses.

Hematological changes during the course of canine babesiosis caused by large Babesia in domestic dogs in Warsaw (Poland)

In the presented study we evaluated the hematological changes in samples of blood obtained from 248 dogs naturally infected with large Babesia. The evaluation included red blood cell count, hemoglobin concentration, hematocrit, mean corpuscular volume (MCV), mean corpuscular hemoglobin concentration (MCHC), leucocyte counts, thrombocyte counts, mean platelet volume (MPV), morphology of erythrocytes and leucogram. The most common disorders in affected dogs were thrombocytopenia and anisocytosis. The count of erythrocytes below reference values was detected in 26.2% of dogs and 31.4% of affected animals presented hematocrit below the reference values. Hemoglobin concentration below the reference values was noted in 29% of dogs, an increase of MCHC above normal values was detected in 21% of examinated dogs and MCV below normal values was recognized in 2% of dogs. 60.5% of dogs presented anisocytosis, 25% poikilocytosis, 23.8% polychromasia, 19.7% hypochromia and 4.4% erythroblastosis. Thrombocytopenia was detected in 99.5% of dogs, but only 15.3% of examined animals showed increase of MPV, which suggests a response of the bone marrow. 36.3% of dogs had neutropenia, and 21.8% presented a left shift, 14.9% had the lymphocytosis and 7.2% lymphopenia.

Association of a common dog leucocyte antigen class II haplotype with canine primary immune-mediated haemolytic anaemia

Immune-mediated haemolytic anaemia (IMHA) is the commonest immune-mediated disease of the dog, representing a major health concern to this species. The aim of this investigation was to determine whether genetic susceptibility to IMHA is associated with genes of the canine major histocompatibility complex (MHC; dog leucocyte antigen system, DLA). Samples were collected from 108 dogs with primary idiopathic, Coombs' positive IMHA. This diseased population was subdivided on the basis of Coombs' test results into two groups: 1) dogs with dominant warm-reactive immunoglobulin (Ig) G haemagglutinins and (2) dogs with an additional or dominant cold-reactive IgM haemagglutinin. The DLA class II alleles and haplotypes of the diseased population were characterised, and these data were compared with those derived from a breed-matched control cohort and a much larger group of DLA-typed dogs. Two haplotypes were increased in the patient group: DLA-DRB1*00601/DQA1*005011/DQB1*00701 (in the group with warm-reactive IgG haemagglutinins only) and DLA-DRB1*015/DQA1*00601/DQB1*00301 (in both groups, but more so in the group with cold-reactive IgM haemagglutinins). One haplotype, DLA-DRB1*001/DQA1*00101/DQB1*00201, was decreased in the total patient group, but this decrease was limited to the warm-reactive IgG haemagglutinins group, and it was actually increased in the cold-reactive IgM haemagglutinins group. A second haplotype, DLA-DRB1*015/DQA1*00601/DQB1*02301, was also decreased in the total patient group, and this decrease was found in both subgroups. In addition, all haplotypes carrying DLA-DRB1*001 were significantly increased in the cold-reactive IgM haemagglutinins group. When the overall patient group was divided on the basis of individual breeds with more than six animals represented, each of the haplotypes could be shown to be implicated in one of the breeds. Thus, it was apparent that different breeds had different MHC associations with canine IMHA, which is similar to the observation that different human ethnic groups can have different HLA associations with the same immune-mediated disease.

Prevalence of Mycoplasma haemofelis, 'Candidatus Mycoplasma haemominutum', Bartonella species, Ehrlichia species, and Anaplasma phagocytophilum DNA in the blood of cats with anemia

Hemoplasmas are known causes of anemia in some cats and some Bartonella species have been associated with anemia in people and in dogs. In this retrospective study, we used polymerase chain reaction (PCR) assays to determine the prevalence rates of Mycoplasma haemofelis, ‘Candidatus M haemominutum’, A phagocytophilum, Ehrlichia species, and Bartonella species DNA in the blood of cats with anemia and a control group of healthy cats. DNA of the organisms was amplified from 22 of 89 cats with anemia (24.7%) and 20 of 87 healthy cats (23.0%). DNA of a hemoplasma was amplified from 18 of 89 cats with anemia (20.2%) and 13 of 87 healthy cats (14.9%); DNA of a Bartonella species was amplified from five of 89 cats with anemia (5.6%) and seven of 87 healthy cats (8.0%). There were no statistically significant differences detected between groups.

Functional canine dendritic cells can be generated in vitro from peripheral blood mononuclear cells and contain a cytoplasmic ultrastructural marker

For physiological and practical reasons the dog is a large animal model used increasingly to study the pathogenesis of human diseases and new therapeutic approaches, in particular for immune disorders. However, some immunological resources are lacking in this model, especially concerning dendritic cells. The aim of our study was to develop an efficient method to generate dendritic cells (DC) in vitro from dog peripheral blood mononuclear cells (PBMC) and to characterize their functional, structural and ultrastructural properties. PBMC were cultured in vitro with IL-4 and GM-CSF. After 1 week of culture, a great proportion of non-adherent cells displayed typical cytoplasmic processes, as evidenced both by optical and electron microscopy. Cytometric analysis revealed the presence of 41.7+/-24.6% CD14+ cells expressing both CD11c and MHC class II molecules. Allogeneic mixed lymphocyte reactions confirmed the ability of these cultures to stimulate the proliferation of allogeneic lymphocytes as already reported as a characteristic of DC in other species. In addition, we describe for the first time the presence in canine DC of cytoplasmic periodic microstructures (PMS) that could represent ultrastructural markers of canine DC. In conclusion, our study provides an easy method to generate DC from PBMC in sufficient numbers for immunological in vitro investigations in dogs, a pre-clinical model for many human diseases.

Flow cytometric evaluation of bound IgG on erythrocytes of anaemic dogs

The detection of red blood cell (RBC)-bound immunoglobulins in case of anaemia with the direct agglutination test (DAT or Coombs test) has been reported to be of low sensitivity. We therefore tested the applicability of flow cytometry for the detection of canine IgG on RBC using two different IgG-specific secondary reagents: goat-anti-dog IgG (GalphaD-IgG) and rabbit-anti-dog IgG (RalphaD-IgG). Membrane staining RBC samples were performed at 4 degrees C. Comparisons of agglutination test at 37 degrees C and 4 degrees C showed, that binding of the secondary antibodies at 4 degrees C was more sensitive compared to agglutination at 37 degrees C and the two antisera differed considerable in their agglutination activity. Binding of GalphaD-IgG and RalphaD-IgG to RBC of healthy dogs (n=15) was low and mean fluorescence intensities were taken to calculate thresholds above which RBC of patients were judged positive. As in agglutination tests, both secondary antisera displayed considerable differences (concentration-dependent binding and histogram profiles) after flow cytometric analysis. Using flow cytometry, with GalphaD-IgG 8 of 17 agglutination-negative patients were positive and RalphaD-IgG was positive with 3 of 3 agglutination-negative RBC samples. Thus, flow cytometric analysis of proved to be a sensitive technique, detecting RBC-bound canine IgG of DAT-negative patients. The results of both techniques, however, are significantly influenced by the used IgG-specific polyclonal reagents.

Importance of blood groups and blood group antibodies in companion animals

Dogs, cats, birds, and ferrets are popular companion animals. Because these pets are considered by many to be family members, they are provided high-quality veterinary medical care, including blood transfusions. This article reviews the current status of blood groups in dogs, cats, birds, and ferrets and discusses the impact of blood groups on veterinary transfusion medicine. One blood group with 3 types has been described in the cat, whereas multiple blood groups have been described in the dog. Only rudimentary knowledge exists regarding pet bird blood groups, and, to date, the ferret appears to be unique because no blood groups have been described. Antibodies against blood group antigens also play a role in animal blood transfusions. Cats have naturally occurring alloantibodies; however, dogs do not appear to have clinically significant naturally occurring alloantibodies. Understanding the issues related to blood groups and blood group antibodies in companion animals will also benefit those using these species as research models for human diseases.

Application of a direct flow cytometric erythrocyte immunofluorescence assay in dogs with immune-mediated hemolytic anemia and comparison to the direct antiglobulin test

A direct flow cytometric erythrocyte immunofluorescence assay (FC) was developed and compared with the direct antiglobulin test (DAT) for detection of erythrocyte-bound immunoglobulin (IgG and IgM) and complement (C3) in dogs with immune-mediated hemolytic anemia (IMHA). Tests were performed on erythrocytes from 13 healthy nonanemic dogs and from 13 anemic dogs with IMHA. The FC and DAT were negative for erythrocyte-bound immunoglobulin in all healthy dogs. The FC was negative for erythrocyte-bound C3 in 12 healthy dogs and positive in 1 healthy dog, and the DAT was negative for C3 in all healthy dogs. Of the 13 IMHA dogs tested for erythrocyte-bound IgG, 12 were positive using the FC and 7 were positive using the DAT. Sensitivity for the detection of erythrocyte-bound IgG in the 26 dogs was 92% for FC and 53% for DAT. Specificity for detection of erythrocyte bound IgG for FC and DAT was 100%. The addition of IgM and/ or C3 did not increase the sensitivity for FC or DAT. In this group of dogs, the FC provided a more rapid, cost-effective, sensitive, objective method to quantitate erythrocyte-bound immunoglobulin and/or complement compared with the currently used DAT.