Imbalance of the interleukin 2 system in children with IDDM

Association between IgE-mediated allergies and diabetes mellitus type 1 in children and adolescents

BACKGROUND

Type 1 diabetes mellitus (T1DM) is characterized by an immunological reaction that is dominated by type-1 T helper (Th1) cells, whereas immunoglobulin E (IgE)-mediated allergies are associated with Th2 cell. According to the Th1/Th2-hypothesis, the immune system is said to either develop into the direction of Th1 or Th2 cells. This would mean that a child developing T1DM is unlikely to develop an IgE-mediated allergy and vice versa.

OBJECTIVE

The aim of the study was to investigate the association between the prevalence of T1DM and IgE-mediated allergies.

METHODS

We designed a prospective case control study with 94 children and adolescents with T1DM and 188 age- and sex-matched control children. The basis of our investigations was a questionnaire concerning the family and children's history as to the presence of IgE-mediated allergies. Moreover, the following blood investigations were done: total serum IgE, specific IgE antibodies to major inhalant allergens, and a multiplex cytokine analysis measuring levels of specific cytokines representing either Th1- or Th2- cytokines.

RESULTS

Children with T1DM reported the presence of IgE-mediated allergies significantly more often than children of the control group. Children with T1DM had significantly higher tumor necrosis factor alpha (TNFα) levels than healthy controls. Levels of interleukin-2 (IL-2) and IL-6 were higher in the groups of children with the presence of a personal history of allergies, regardless of the presence of T1DM.

CONCLUSIONS

Our results suggest that T1DM is associated with a higher risk of a self-reported presence of IgE-mediated allergies and that the Th1/Th2-hypothesis may be an oversimplification.

No alterations in the frequency of FOXP3+ regulatory T-cells in type 1 diabetes

Regulatory T-cells (Tregs) play a critical role in maintaining dominant peripheral tolerance. Previous characterizations of Tregs in type 1 diabetes have used antibodies against CD4 and alpha-chain of the interleukin-2 receptor complex (CD25). This report extends those investigations by the addition of a more lineage-specific marker for Tregs, transcription factor forkhead box P3 (FOXP3), in subjects with type 1 diabetes, their first-degree relatives, and healthy control subjects. With inclusion of this marker, two predominant populations of CD4(+)CD25(+) T-cells were identified: CD4(+)CD25(+)FOXP3(+) as well as CD4(+)FOXP3(-) T-cells expressing low levels of CD25 (CD4(+)CD25(LOW)FOXP3(-)). In all study groups, the frequency of CD4(+)CD25(+)FOXP3(+) cells was age independent, whereas CD4(+)CD25(LOW)FOXP3(-) cell frequencies strongly associated with age. In terms of additional markers for delineating cells of Treg lineage, FOXP3(+) cells were CD127(-) to CD127(LOW) whereas CD25(+) cells were less restricted in their expression of this marker, with CD127 expressed across a continuum of levels. Importantly, no differences were observed in the frequency of CD4(+)CD25(+)FOXP3(+) T-cells in individuals with or at varying degrees of risk for type 1 diabetes. These investigations suggest that altered peripheral blood frequencies of Tregs, as defined by the expression of FOXP3, are not specifically associated with type 1 diabetes and continue to highlight age as an important variable in analysis of immune regulation.

Serum IL-1beta, IL-2, and IL-6 in insulin-dependent diabetic children

Insulin-dependent diabetes mellitus (IDDM) is a chronic disease characterized by T-cell-dependent autoimmune destruction of the insulin-producing β cells in the pancreatic islets of Langerhans, resulting in an absolute lack of insulin. T cells are activated in response to islet-dominant autoantigens, the result being the development of IDDM. Insulin is one of the islet autoantigens responsible for the activation of T-lymphocyte functions, inflammatory cytokine production, and development of IDDM. The aim of this study was to investigate serum concentrations of interleukin (IL)-1β, IL-2, IL-6, and tumor necrosis factor (TNF)-α in children IDDM. The study population consisted of 27 children with IDDM and 25 healthy controls. Children with IDDM were divided into three subgroups: (1) previously diagnosed patients (long standing IDDM) (n : 15), (2) newly diagnosed patients with diabetic ketoacidosis (before treatment) (n : 12), and (3) newly diagnosed patients with diabetic ketoacidosis (after treatment for two weeks) (n : 12). In all stages of diabetes higher levels of IL-1β and TNF- α and lower levels of IL-2 and IL-6 were detected. Our data about elevated serum IL-1β, TNF- α and decreased IL-2, IL-6 levels in newly diagnosed IDDM patients in comparison with longer standing cases supports an activation of systemic inflammatory process during early phases of IDDM which may be indicative of an ongoing β-cell destruction. Persistence of significant difference between the cases with IDDM monitored for a long time and controls in terms of IL-1β, IL-2, IL-6, and TNF-α supports continuous activation during the late stages of diabetes.

Altered natural killer cells in type 1 diabetic patients

Evidence from animal models suggests that natural killer (NK) cells can be important players in the development of type 1 diabetes, although data in humans are still sparse. We studied the frequency and activation state of blood NK cells at different stages of human type 1 diabetes, and whether genetic or phenotypic NK cell peculiarities could be associated with an early onset of diabetes. The onset period is marked by a slight reduction in blood NK cells, but these are unusually activated in some patients (gamma-interferon expression). This activation status does not correlate, however, with a particularly young age at onset. In contrast, NK cells in patients with long-standing type 1 diabetes had a markedly lower expression of p30/p46 NK-activating receptor molecules compared with those of control subjects. A slightly decreased expression of NKG2D in all type 1 diabetic patients relative to control subjects was observed, independent of the duration of disease, parallel to prior observations in the NOD mouse. Finally, type 1 diabetic patients had an increased frequency of KIR gene haplotypes that include the activating KIR2DS3 gene, with a genetic interaction between the KIR and HLA complexes. The reduced activation of NK cells in individuals with long-standing type 1 diabetes would seem to be a consequence rather than a cause, but other peculiarities may relate to type 1 diabetes pathogenesis.

Prevalence of peripheral neuropathy in type 2 diabetic patients attending a diabetes center in Turkey

The aim of this study was to determine the prevalence and risk factors for neuropathy in type 2 diabetic patients attending a major Turkish diabetes center. Eight hundred and sixty-six consecutive type 2 diabetic patients were included in the study. A single observer performed biothesiometry studies on these patients. The presence of diabetic neuropathy was investigated using neurological symptom scale (NSS) and neurological disability score (NDS) performed. Neuropathy was determined with standardized neurological examinations and defined as the presence of abnormal NSS and NDS together with abnormal sensory or motor signs and symptoms as well as decreased great toe vibration perception. Overall, 60% (n = 520) of the patients were diagnosed as having neuropathy. The prevalence of neuropathy increased with age (p < 0.001) and duration of diabetes (p < 0.001). Multiple logistic regression analysis revealed the duration of diabetes (p < 0.001) and HbA1c levels (p < 0.001) as the risk factors for neuropathy. The overall prevalence of neuropathy in Turkish type 2 diabetic population was 60%. Age, duration of diabetes, and poor glycemic control were considered to be the risk factors for neuropathy.

Independent involvement of CD8+ CD25+ cells and thyroid autoantibodies in disease severity of Hashimoto's disease

Hashimoto's disease (HD) is well known as an autoimmune thyroid disease caused by the destruction of the thyroid follicles, and can be diagnosed in the subclinical stage with thyroid-specific autoantibodies. However, some patients with HD develop hypothyroidism and are treated with thyroxine (severe HD), but most do not throughout their lives (mild HD). To clarify the immunologic differences between these two groups of patients with HD, we examined serum thyroid autoantibodies (antithyroid peroxidase antibodies and antithyroglobulin antibodies), CD4+ CD25+ cells that contain regulatory T cells and activated helper T cells, and CD8+ CD25+ cells that are activated cytotoxic T cells. There was no significant difference in CD4+ CD25+ cells between these HD groups, although the proportion of CD25+ cells within CD4+ cells increased in both groups as compared to normal controls. The serum titers of the thyroid autoantibodies and the proportion of CD25+ cells within CD8+ cells were higher in patients with severe HD than in those with mild HD. There was no correlation between these two parameters, and a two-dimensional analysis with these parameters differentiated these two groups of patients with HD more clearly. These results indicate that both thyroid autoantibodies and CD8+ CD25+ cells are independently involved in the disease severity of HD and CD4+ CD25+ cells are not related to the severity of HD.

Constitutive impaired TCR/CD3-mediated activation of T cells in IDDM patients co-exist with normal co-stimulation pathways

IDDM is a T cell-mediated autoimmune disease which is paradoxically associated with T cell functional deficiencies. The proliferative response of PBMC under CD3-, Vbeta2-, Vbeta8- and Vbeta7-stimulation was investigated in IDDM and NIDDM patients, non-diabetic first-degree relatives and control subjects. Despite normal surface expression of the TCR/CD3 complex, the TCR/CD3-mediated proliferation of PBMC from IDDM patients was significantly impaired compared to control subjects (P<0.05). This defect was specific for the autoimmune disease, constitutive and not linked to the class II MHC genotype, to metabolic disturbances or to presence of specific autoantibodies. Inefficient activation of T cells was not related to a lower capacity of CD28 to transduce co-stimulative signals because proliferative responses under CD2/CD28 stimulations were similar in IDDM and control groups. The IL-2/IL-2 receptor system was functional because unstimulated PBMC proliferated in response to increasing amounts of IL-2. Nevertheless, despite normal expression of CD25, addition of IL-2 did not normalize the proliferative defect linked to IDDM. In conclusion, excluding a faulty co-stimulation pathway, these results are in favour of a constitutive defect in the CD3/TCR transduction machinery, increasing sensitivity to apoptosis or anergy in T cells from IDDM patients.

Decreased secretion of Th2 cytokines precedes Up-regulated and delayed secretion of Th1 cytokines in activated peripheral blood mononuclear cells from patients with insulin-dependent diabetes mellitus

Recent evidence suggests that autoimmune animal diabetes is associated with an imbalance between the Th1 and Th2 arms of the cellular immune system. However, limited data is available regarding the Th1/Th2 imbalance in human Insulin dependent diabetes mellitus (IDDM) patients. Therefore, we examined the peak levels, secretory pattern and total cytokine production (calculated as the area under the curve, AUC) of the Th1 cytokines, IL-2 and IFN-gamma, and Th2 cytokines, IL-4 and IL-10, from stimulated peripheral blood mononuclear cells, from 17 IDDM patients and 24 normal controls. In contrast to controls, diabetic patients were characterized by an early, uniformly low secretion of Th2 cytokines, followed by a late increased secretion of Th1 cytokines. This resulted in significant differences in secretory patterns of IFN-gammaIL-2, IL-4 and IL-10 between the two groups; P<0.001, P<0.005, P<0.005 and P<0.001, respectively. No correlation was found in the diabetic patients between any profiles of the cytokines and their various clinical parameters, including age, gender, disease duration, insulin requirements or glycated hemoglobin levels. In conclusion, our data provides the first comprehensive evidence for an independent and persistent impairment of both Th1 and Th2 cytokine secretory patterns in IDDM patients.

Peripheral T-cell activation in non-segmental vitiligo

Vitiligo is a hypopigmentary dermatosis of probable autoimmune origin. Previously reported aberrations in peripheral blood mononuclear cells (PBMC), especially T cells and T cell subsets, have been inconsistent. Lymphocyte subpopulations were examined using flow cytometry and monoclonal antibodies against CD4, CD8, CD20, CD25, CD45RA, and HLA-DR in 34 patients with non-segmental vitiligo. Twelve patients had not received any previous treatment and 22 had previously received at least one course of PUVA therapy that was discontinued at least four months prior to our study. Compared to matched controls, we found significant increases in CD25 and HLA-DR in vitiligo patients (p = 0.000). An inverse correlation was observed between HLA-DR and patient status with regard to treatment (p = 0.001). These results suggest a role for T cells in the pathogenesis of vitiligo and imply that previous PUVA therapy may be reflected by an alteration in circulating DR +ve cells.