Changes in peripheral lymphocyte subsets in the type 1 diabetic dogs treated with insulin injections

Lymphocyte immunophenotyping in dogs with lymphopenia of common causes

Lymphocyte immunophenotyping can be useful for evaluating immune competence and predicting the disease prognosis. It is essential to gain knowledge about canine lymphocyte immunophenotypes in various conditions. The study deals with the characteristics of lymphopenia in dogs, with an emphasis on lymphocyte immunophenotyping by flow cytometry. Blood samples from 44 dogs with lymphopenia were included in the study. All lymphopenias sent from veterinary clinics to the diagnostic laboratory were analyzed. The hematological and biochemical abnormalities were investigated, as well as the effect of the age. Lymphopenias were classified according to the level of C-reactive protein (CRP). The percentage of T cells, B cells, T_h cells and T_c cells, and T/B and T_h/T_c ratios were determined by flow cytometry. Lymphopenias often occurred in dogs over 7 years of age (79.5 %). The most common were postoperative lymphopenia (31.8 %) and inflammatory diseases (29.5 %), most commonly affecting the gastrointestinal tract. Frequent abnormalities were monocytosis (56.8 %), increased CRP (72.7 %) and decreased albumin/globulin ratio (50.0 %). The percentage of T_h lymphocytes was significantly lower in the group with elevated CRP than in the group with basal CRP (P = 0.0329). A negative correlation was found between the level of CRP and the percentage of T_h lymphocytes (r = -0.3278, P = 0.0390). This study provided new insights into the appearance, incidence and classification of canine lymphopenia.

A variable CD3⁺ T-cell frequency in peripheral blood lymphocytes associated with type 1 diabetes mellitus development in the LEW.1AR1-iddm rat

Purpose

The LEW.1AR1-iddm rat is an animal model of human type 1 diabetes mellitus (T1DM), which arose through a spontaneous mutation within the MHC-congenic inbred strain LEW.1AR1 (RT1^r2). In contrast to the diabetes-resistant LEW.1AR1 background strain in LEW.1AR1-iddm rats a highly variable T-cell frequency could be observed in peripheral blood lymphocytes (PBLs).

Methods

In this study we therefore characterised the T-cell repertoire within the PBLs of the two strains by flow cytometry analysis and identified the CD3⁺ T-cell phenotype and its possible linkage to diabetes susceptibility. To map loci conferring susceptibility to variable CD3⁺ T-cell frequency, backcross strains (N2) were generated with the genetically divergent BN and PAR rats for microsatellite analysis.

Results

The LEW.1AR1-iddm rat strain was characterised by a higher variability of CD3⁺ T-cells in PBLs along with a slightly decreased mean value compared to the LEW.1AR1 background strain. The reason for this reduction was a decrease in the CD4⁺ T-cell count while the CD8⁺ T-cell proportion remained unchanged. However, both T-cell subpopulations showed a high variability. This resulted in a lower CD4⁺/CD8⁺ T-cell ratio than in LEW.1AR1 rats. Like LEW.1AR1-iddm rats all animals of the backcross populations, N2 BN and N2 PAR rats, also showed large variations of the CD3⁺ T-cell frequency. The phenotype of variable CD3⁺ T-cell frequency mapped to the telomeric region of chromosome 1 (RNO1), which is identical with the already known Iddm8 diabetes susceptibility region. The data indicate that a variable CD3⁺ T-cell frequency in PBLs is genetically linked to diabetes susceptibility in the LEW.1AR1-iddm rat.

Conclusion

The T-cell variability in PBLs could be related to the previously reported imbalance between regulatory and effector T-cell populations which results in beta-cell autoimmunity. Since similar T-cell phenotypes have also been described in human T1DM the identification of the functional role of the observed variable CD3⁺ T-cell frequency may help to understand the mechanisms of autoimmunity in T1DM.

Successful intensive insulin treatment of type 1 diabetic dogs leads to restoration of peripheral leukocyte insulin signaling gene expression and enzyme activities

The purpose of this study was to investigate whether intensive insulin treatment of dogs suffering from type 1 diabetes mellitus, resulting in tight glycemic control, could be reflected by changes in peripheral leukocyte metabolism. Specifically, plasma metabolites and enzyme activities were assessed. In addition, quantitative RT-PCR was used to determine changes in insulin signaling gene (insulin receptor substrate (IRS)-1, IRS-2 and phosphatidylinositol 3-kinase (PI3-K) P85alpha) mRNA levels in peripheral leukocytes. Lastly, leukocyte enzymes involved in cellular energy metabolism were examined for changes in glucose utilization. Our results indicated that intensive insulin treatment was successful in type 1 DM dogs, leading to tight glycemic control. The mean glucose concentration and glycated albumin percentage significantly decreased to 156 mg/dl and 15.6%, respectively, following treatment. In peripheral leukocytes, the IRS-2 and PI3-K p85alpha mRNA levels significantly increased, and a significant increase in pyruvate kinase and pyruvate carboxylase activity, two enzymes involved in cellular energy metabolism, was also observed post treatment. Therefore, the observed changes in insulin signaling pathway activity and cellular energy metabolism enzyme activity in peripheral leukocytes are considered to be characteristics of amelioration of glucose metabolism by insulin action. As such, peripheral leukocytes are sufficiently sensitive to monitor for improving glycemic control during intensive insulin treatment of type 1 DM dogs. Blood cells such as leukocytes are much more readily available than muscle or adipose tissue for studies in dogs.

Assessing the immune state of dogs suffering from pituitary gland dependent hyperadrenocorticism by determining changes in peripheral lymphocyte subsets

In order to evaluate the immune state of dogs suffering from pituitary-dependent hyperadrenocorticism (PDH), peripheral lymphocyte subsets were examined. Twenty seven PDH dogs and eight healthy control dogs were used in the current study. Eight healthy dogs served as the control group. Twenty seven PDH dogs were categorized into 4 groups based on their post serum cortisol concentrations by ACTH stimulation test: 2-5, excellent control (n = 8); 5-20, fair control (n = 7); >20, poor control (n = 4); and untreated (n = 8). Cell counts were executed with white blood cells (WBC), lymphocytes, CD3(+) (T lymphocytes), CD4(+) (Helper T lymphocytes), CD8(+) (Cytotoxic T lymphocytes), CD21(+) (B lymphocytes) cells in addition to calculating CD4(+)/CD8(+) ratio. Results indicated a significant difference in lymphocyte numbers and lymphocyte subset populations (CD3(+), CD4(+), CD8(+), and CD21(+) cells) between PDH and control dogs. Moreover, comparison of the PDH groups (excellent control; fair control; poor control; untreated) demonstrated that all groups had a significant decrease in lymphocytes numbers (CD3(+), CD4(+) and CD21(+) cell counts) as compared to control group. Meanwhile, no significant differences were observed in WBC counts and CD4(+)/CD8(+) ratio between groups. Furthermore, lymphocyte subset distribution in excellent control PDH dogs without concurrent disease (n = 4) better resembled that of control dogs as compared to PDH dogs with concurrent disease (n = 4). PDH dogs may be suffering from an immuno-depressed state as evidenced by significant differences in lymphocyte subset populations. Furthermore, treatment of both PDH and concurrent disease might improve lymphocyte subset distribution.

Neutrophil response of anaerobic jump trained diabetic rats

This paper investigated the effect of jump training on blood biochemical parameters and neutrophil responses of diabetic rats. Male Wistar rats were divided into control, trained, diabetic and trained-diabetic groups. Diabetes was induced by i.v. injection of streptozotocin. Jump training consisted of six sets of ten jumps in water with overload of 50% of body mass with 1-min of resting, four times per week during 6 weeks. Plasma glucose, lactate, triacylglycerol and total cholesterol concentrations, differential leukocyte count, phagocytosis and anion superoxide production by neutrophils were evaluated. Diabetes caused hyperglycemia, hypertriacylglycerolemia, and body weight loss. Physical training reversed hypertriacylglycerolemia. Jump training increased phagocytosis and anion superoxide production by blood neutrophils from trained and trained-diabetic rats. Neutrophilia and lymphocytopenia occur in diabetic and trained-diabetic rats. Anaerobic jump training in diabetic rats reduced hypertriacylglycerolemia and increased neutrophil anion superoxide production. Phagocytosis was not altered in trained-diabetic rats.