Long-term changes of Th17 and regulatory T cells in peripheral blood of dogs with spinal cord injury after intervertebral disc herniation

BACKGROUND

Intervertebral disc herniation (IVDH) is one of the most common causes of spinal cord injury (SCI) in dogs. As a result of acute SCI, a complex inflammatory response occurs in the spinal cord. Th17 cells (Th17) produce pro-inflammatory cytokines, while regulatory T cells (Treg) have opposite effects producing anti-inflammatory cytokines. Therefore, the aim of this study was to determine whether Th17- and Treg cells are involved in the pathogenesis of SCI or whether cellular changes occur due to coexisting inflammatory diseases. We hypothesized that chronic alterations in the Th17/Treg ratio are associated with a worse outcome after SCI.

METHODS

Twenty-six paretic or plegic dogs with IVDH with and without coexisting inflammatory disease were investigated in the acute stage of the disease and after recovery of SCI. In addition, a healthy control group was included (n = 14). Quantification of Th17 and Treg cells, from peripheral blood samples, was performed by multicolor flow cytometry and IL17 was measured using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

After recovery significantly higher levels of Th17 (p = 0.0265) and Treg cells (p = 0.00025) were detected compared to acute IVDH but Th17/Treg ratio did not differ significantly. Recovered dogs and the control group did not differ significantly from each other. No association between an imbalance in the ratio and neurologic severity or underlying inflammatory diseases was found.

CONCLUSION

This study demonstrated that altered Th17 and Treg levels in peripheral blood are altered in the acute stage of IVDH, preexisting inflammatory diseases seem not to influence these cell populations. Th17 and Treg cells could be considered when evaluating new treatment strategies for SCI.

Interleukin 10 and transforming growth factor-beta 1 plasma levels in atopic dogs before and during immunotherapy

BACKGROUND

Human studies suggest that the cytokines, interleukin 10 (IL-10) and transforming growth factor-beta 1 (TGF-ß1) may play an important role in allergen-specific immunotherapy (ASIT). However, there is little known about the function of these cytokines in atopic dogs. This study compared the plasma levels of IL-10 and TGF-ß1 in atopic and control dogs and investigated their changes during different ASIT approaches.

METHODS

A total of 54 atopic and 32 control dogs were included. Immunotherapy was performed in 30 atopic dogs. The dogs undergoing immunotherapy were allocated to four groups of different ASIT approaches (namely subcutaneous, intralymphatic, sublingual ASIT and subcutaneous ASIT with recombinant allergens). Blood samples were collected at four timepoints throughout the one year of ASIT. Canine atopic dermatitis extent and severity index, pruritus visual analogue scale and medication score were recorded at each timepoint. Commercially available ELISA kits were used to quantify IL-10 and TGF-ß1 in plasma.

RESULTS

There was no significant difference in IL-10 and TGF-ß1 between atopic and control dogs. The IL-10 levels were significantly increased in the intralymphatic group at the end of the study. No significant differences were found in the other groups for both IL-10 and TGF-ß1.

CONCLUSION

The findings of this work suggest that IL-10 and TGF-ß1 cannot be used to monitor the course of the disease during ASIT.

Regulatory T cells promote alloengraftment in a model of late-gestation in utero hematopoietic cell transplantation

In utero hematopoietic cell transplantation (IUHCT) has the potential to cure congenital hematologic disorders including sickle cell disease. However, the window of opportunity for IUHCT closes with the acquisition of T-cell immunity, beginning at approximately 14 weeks gestation, posing significant technical challenges and excluding from treatment fetuses evaluated after the first trimester. Here we report that regulatory T cells can promote alloengraftment and preserve allograft tolerance after the acquisition of T-cell immunity in a mouse model of late-gestation IUHCT. We show that allografts enriched with regulatory T cells harvested from either IUHCT-tolerant or naive mice engraft at 20 days post coitum (DPC) with equal frequency to unenriched allografts transplanted at 14 DPC. Long-term, multilineage donor cell chimerism was achieved in the absence of graft-versus-host disease or mortality. Decreased alloreactivity among recipient T cells was observed consistent with donor-specific tolerance. These findings suggest that donor graft enrichment with regulatory T cells could be used to successfully perform IUHCT later in gestation.

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+CD25high 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.

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.

Immunological and angiogenic markers during metronomic temozolomide and cyclophosphamide in canine cancer patients

Metronomic chemotherapy stimulates the immune response via depletion of regulatory T cells (Tregs) and suppresses angiogenesis by modulating the secretion of thrombospondin-1 (TSP-1) and vascular endothelial growth factor (VEGF). In this study, blood was collected from 10 healthy dogs and from 30 canine cancer patients before and 2 and 4 weeks after treatment with metronomic temozolomide (6.6 mg m^-2 ), cyclophosphamide (12.5 mg m^-2 ) or cyclophosphamide and temozolomide. The percentage of circulating CD25⁺ Foxp3⁺ CD4⁺ Tregs and the plasma levels of TSP-1 and VEGF were measured. There was a significant difference in the percentage of Tregs between cancer patients and healthy dogs. A significant decrease in Tregs was noted in patients treated with metronomic cyclophosphamide and the combination. Treatment with temozolomide had no effect on the percentage of Tregs. TSP-1 and VEGF levels were, respectively, significantly lower and higher in cancer patients than in healthy dogs, but they were not influenced by any of the studied metronomic treatment regimens.

Regulatory T cells in dogs with multicentric lymphoma: peripheral blood quantification at diagnosis and after initial stage chemotherapy

Lymphoma is the most common hematopoietic malignancy in dogs and one of the most frequent among all neoplastic diseases in this species. It can occur in several anatomical locations with distinct histological and immunophenotypes. Depending on the host immune response towards the tumor, prognosis information could be collected. Because its well established immunosuppressant, antitumor activity, the function of regulatory T cells (Tregs) in canine neoplasias has been investigated. In this study, we sought to quantify, using flow cytometry, the Tregs subpopulation in peripheral blood of healthy dogs (10) and in those diagnosed with type-B (14) and type-T (8) multicentric lymphoma before (at diagnosis) and after the first cycle (5-week) of 19-week Madison-Wisconsin (MW) protocol of chemotherapy. Our results indicated that dogs with lymphoma showed higher percentage of Tregs (18,84±2,56) when compared to healthy dogs (4,70±0,50) (P<0,01). In addition, 5-week chemotherapy treatment reduced the Tregs subpopulation (7,54±1,08) to levels similar to control (4,70±0,50) (P>0,05). There was no difference in Tregs percentage between B-type (17,45±2,77) and T-type (21,27±5,27) lymphoma (P>0,05). With this, we conclude that canine lymphoma increases Tregs in the peripheral blood and the MW protocol of chemotherapy reduces this cell subpopulation to control values.

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

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