Study of T-cell activation in type I diabetic patients and pre-type I diabetic subjects by cytometric analysis: antigen expression defect in vitro

Effect of Epstein-Barr Virus Infection on Selected Immunological Parameters in Children with Type 1 Diabetes

Diabetes mellitus is a group of metabolic disorders with different etiologies, pathogeneses and clinical pictures, characterized by chronic hyperglycemia due to abnormal insulin secretion or action. Type 1 diabetes mellitus is the most common type of diabetes mellitus in children and adolescents, accounting for about 90% of diabetes in the population under the age of 18. The etiopathogenesis of type 1 diabetes is multifactorial. The disease occurs as a result of the interaction of three factors: genetic predisposition, environmental factors and the immune response. Research in recent years has focused on the involvement of Epstein-Barr virus (EBV) in the pathogenesis of type I diabetes. The goals of treating type 1 diabetes include maintaining blood-glucose, fructosamine and glycated hemoglobin (HbA1c) levels; therefore, the main purpose of this study was to evaluate the effect of EBV infection on the activation of selected immune cells, fructosamine levels and HbA1c levels in children with type I diabetes. Based on our study, we found a lower percentage of CD8+ T lymphocytes with expression of the CD69 molecule in patients with anti-VCA antibodies in the IgG class, and a lower percentage of CD8+ T lymphocytes with expression of the CD25+ molecule in patients with anti-EBNA-1 antibodies in the IgG class, which may indicate limited control of the immune system during EBV infection in patients. There was a lower percentage of CD3+CD4+ T lymphocytes secreting IL-4 in the study group, indicating that a deficiency in IL-4 production may be related to the development of type 1 diabetes. There was an increase in the percentage of CD4+CD3+IL-10 lymphocytes in the study group with anti-VCA antibodies present in the IgG class and anti-EBNA-1 antibodies in the IgG class compared to the patients without antibodies. In addition, there was a significant increase in fructosamine levels and higher glycated hemoglobin levels in the study group with antibodies to EBV antigens. In addition, an increase in the percentage of T lymphocytes with a CD4+CD3+IL-17+ phenotype in the patients with anti-VCA IgG antibodies was confirmed, and higher HbA1c levels may suggest that EBV infection is accompanied by an increase in IL-17 secretion.

Genetic and Molecular Basis of QTL of Diabetes in Mouse: Genes and Polymorphisms

A systematic study has been conducted of all available reports in PubMed and OMIM (Online Mendelian Inheritance in Man) to examine the genetic and molecular basis of quantitative genetic loci (QTL) of diabetes with the main focus on genes and polymorphisms. The major question is, What can the QTL tell us? Specifically, we want to know whether those genome regions differ from other regions in terms of genes relevant to diabetes. Which genes are within those QTL regions, and, among them, which genes have already been linked to diabetes? whether more polymorphisms have been associated with diabetes in the QTL regions than in the non-QTL regions.

Our search revealed a total of 9038 genes from 26 type 1 diabetes QTL, which cover 667,096,006 bp of the mouse genomic sequence. On one hand, a large number of candidate genes are in each of these QTL; on the other hand, we found that some obvious candidate genes of QTL have not yet been investigated. Thus, the comprehensive search of candidate genes for known QTL may provide unexpected benefit for identifying QTL genes for diabetes.

Effects of moderate and severe malnutrition in rats on splenic T lymphocyte subsets and activation assessed by flow cytometry

Malnutrition is distributed widely throughout the world and is a particular problem in developing countries. Laboratory animals have been very useful in studying the effects of varying levels of malnutrition because non-nutritional factors that affect humans may be controlled. The objective of the present study was to determine the effects of moderate and severe malnutrition on lymphocyte proportions and activation markers of T cells in experimentally malnourished rats during lactation by flow cytometry. Lower absolute (total) and relative (%) numbers of CD3+ and CD4+ lymphocyte subpopulations were observed in moderately (second degree) and severely (third degree) malnourished rats compared with well-nourished rats (P < 0.05). Both groups of malnourished rats showed a significant decrease in the percentage of CD71+ cells at 24 h post-activation with phytohaemagglutinin (PHA). After 24 h activation of spleen cells with PHA, a lower percentage of CD25+ cells was observed in malnourished than well-nourished rats (P < 0.05). In conclusion, the results of this study indicated an altered expression of CD71 and CD25 during activation of T lymphocytes in malnourished rats and may partially explain increased susceptibility to infection associated with malnutrition. Moreover, these results demonstrated that moderate malnutrition affects the response of T lymphocytes as much as severe malnutrition.

Effect of insulin-dependent diabetes mellitus on response to extracorporeal photopheresis in patients with Sézary syndrome

BACKGROUND

Extracorporeal photopheresis (ECP) has become a primary therapy for selected forms of cutaneous T-cell lymphoma, especially Sézary syndrome. Variability in response of patients with Sézary syndrome to ECP has been reported.

OBJECTIVE

Our purpose was to determine whether underlying medical conditions influence the efficacy of ECP in patients with Sézary syndrome.

METHODS

We retrospectively reviewed the medical records of 55 patients with Sézary syndrome who received ECP between 1987 and 2000. Efficacy criteria included decrease in Sézary cell count, erythroderma, lymphadenopathy, organomegaly, and pruritus.

RESULTS

Thirty-four patients responded well and 10 patients responded partially to ECP; 11 patients had no response. Nine patients with no response to ECP had insulin-dependent diabetes mellitus (IDDM). IDDM was documented in only 2 patients with a good response and in no patients with a partial response to ECP.

CONCLUSION

Patients with Sézary syndrome and IDDM typically respond poorly to the standard ECP treatment regimen.

Specific deficiency of p56lck expression in T lymphocytes from type 1 diabetic patients

Peripheral T lymphocyte activation in response to TCR/CD3 stimulation is reduced in type 1 diabetic patients. To explore the basis of this deficiency, a comprehensive analysis of the signal transduction pathway downstream of the TCR/CD3 complex was performed for a cohort of patients (n = 38). The main result of the study shows that T cell hyporesponsiveness is positively correlated with a reduced amount of p56(lck) in resting T lymphocytes. Upon CD3-mediated activation, this defect leads to a hypophosphorylation of the CD3zeta-chain and few other polypeptides without affecting the recruitment of ZAP70. Other downstream effectors of the TCR/CD3 transduction machinery, such as phosphatidylinositol 3-kinase p85alpha, p59(fyn), linker for activation of T cells (LAT), and phospholipase C-gamma1, are not affected. In some patients, the severity of this phenotypic deficit could be linked to low levels of p56(lck) mRNA and resulted in the failure to efficiently induce the expression of the CD69 early activation marker. We propose that a primary deficiency in human type 1 diabetes is a defect in TCR/CD3-mediated T cell activation due to the abnormal expression of the p56(lck) tyrosine kinase.

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.

Defective activation of p21ras in peripheral blood mononuclear cells from patients with insulin dependent diabetes mellitus

We previously reported that a decreased TCR mediated activity of the GTP-GDP binding p21ras protooncogene is associated with prediabetes in non-obese diabetic (NOD) mice. Furthermore, prevention of autoimmune diabetes is associated with reversal of the p21ras signaling defect in NOD T cells. Based on these animal studies we determined the activation of p21ras in PBMC from patients with Insulin Dependent Diabetes Mellitus (IDDM), Non-Insulin Dependent Diabetes Mellitus (NIDDM) and normal healthy controls. Stimulation by PHA induced a decrease of 3.7 +/- 1.4% and an increase of 2.44 +/- 2.3%, p < 0.02 and 2.6 +/- 1.6%,p < 0.003 in the basal unstimulated p21ras activity in the IDDM, NIDDM and normal control groups, respectively. Expression of p21ras and its regulatory elements, the GTPase activating protein p120ras-GAP and the guanine nucleotide releasing factor (GNRF) hSOS, was comparable in the three groups. The in vitro proliferative response to PHA was comparable in the IDDM and control groups: stimulation index (SI) of 8.6 +/- 2.5 and 9.4 +/- 3.5 respectively, p < 0.44. No correlations were found in the IDDM patients between the degree of p21ras activation and the mitogen induced in vitro proliferative response or the various clinical parameters including age, gender, disease duration, daily insulin requirements and metabolic control. Taken together these data indicate that PBMC from IDDM patients are characterized by a persistent impairment in the activation of their p21ras. They also suggest that p21ras stimulated activity is a sensitive and independent parameter of PBMC activation in these patients.

Multidose streptozotocin induction of diabetes in BALB/cBy mice induces a T cell proliferation defect in thymocytes which is reversible by interleukin-4

Thymic T cell function in streptozotocin-treated (STZ) diabetic mice has been examined. STZ administration suppresses thymic T cell proliferation in response to mitogen stimulation in vitro. Secretion of IL-4 was dramatically reduced; however, secretion of IL-2 or IFN-gamma was not significantly inhibited. RT-PCR analysis of thymocyte RNA revealed that levels of IL-4 mRNA were dramatically decreased in STZ-treated mice. Levels of mRNA encoding IFN-gamma were similar, but the appearance was delayed in thymocytes derived from STZ-treated mice, implying differential regulation of IL-4 and IFN-gamma. Defective thymocyte proliferation was partially restored by exposure to IL-2 in vitro; however, IL-4 completely reversed the STZ-induced defect. Administration in vivo of IL-4 before STZ treatment reversed the STZ-induced thymocyte proliferation defect and prevented both pancreatic islet destruction and hyperglycemia. Thymocyte cell surface differentiation markers were not appreciably different from control mice. Collectively these experiments suggest that STZ treatment of mice reduces expression of IL-4 which is associated with development of autoimmune diabetes.

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.

Increased CD69 and human leukocyte antigen-DR expression on T lymphocytes in insulin-dependent diabetes mellitus of long standing

To better define prevailing activation of circulating T cell subsets in insulin-dependent diabetes mellitus (IDDM) of recent onset (DM; n = 31; median age +/- SD, 28 +/- 6.9 yr) and of long standing (DML; n = 27; age, 33 +/- 10.4 yr; median duration of disease, 105 months), CD4+ and CD8+ T cells were analyzed to determine their naive and memory subsets as well as their expression of human leukocyte antigen (HLA)-DR, interleukin-2 receptor alpha-chain (CD25), and CD69 by three-color flow cytometry. Twenty-six healthy subjects (HS; age, 32.0 +/- 8.2 yr) served as controls. No deviation was seen in either IDDM group compared to HS in CD25 expression on CD4+ or CD8+ cells or in their CD45RA+ or CD45RA- subsets. HLA-DR expression, however, was increased (P < 0.05) in total CD8+ cells and CD45RA+ cells, with CD45RA- CD8+ cells joining the prevailing pattern only in DML. Among CD4+ cells, increased expression of HLA-DR molecules was restricted to total and CD45RA- cells in DML. CD69 expression did not differ between IDDM and HS, but differed between DML (CD4+, CD8+, and CD45RA- CD4+) and DM only. In conclusion, our data demonstrate that HLA-DR expression in IDDM is restricted to memory cells (CD45RA-) among CD4+ cells in DML and is more markedly confined to naive (CD45RA+) than to memory CD8+ cells, whereas the early activation antigen CD69 is more readily expressed in DML than in DM. The observed activation of circulating T cells suggests an ongoing immune process in IDDM both at clinical manifestation and after long duration.

A whole-blood assay for qualitative and semiquantitative measurements of CD69 surface expression on CD4 and CD8 T lymphocytes using flow cytometry

A whole-blood flow cytometry-based assay was utilized to assess CD4 and CD8 T-lymphocyte activation in response to phytohemagglutinin (PHA) stimulation. T-lymphocyte activation was assessed by qualitative (percent CD69) and semiquantitative (anti-CD69 antibody binding capacity) measurements of CD69 surface expression. Whole-blood samples from 21 healthy and 21 human immunodeficiency virus (HIV)-infected (<500 absolute CD4 counts per mm3) individuals were stimulated with 20 microg of PHA per ml for 18 to 24 h. The proportions of activated CD4 and CD8 T lymphocytes expressing CD69 (percent CD69) and the levels of CD69 expression on each T-lymphocyte subset (anti-CD69 antibody binding capacity) were measured. By using this assay system, T-lymphocyte activation was impaired in both CD4 and CD8 T-lymphocyte subsets of HIV-infected individuals. The proportions of CD69-positive CD4 and CD8 T lymphocytes were 43 and 27% lower, respectively, in samples from HIV-infected individuals compared to samples from healthy individuals. Similarly, the levels of CD69 expression on each activated CD4 and CD8 T-lymphocyte subset were 48 and 51% lower, respectively. These results suggest that both qualitative and semiquantitative measurements of CD69 surface expression by flow cytometry can be used to assess T-lymphocyte activation.

In vitro T cell activation in elderly individuals: failure in CD69 and CD71 expression

A large number of T cell dysfunctions have been observed in the elderly. The most widely observed is the inability of these cells to proliferate at a level comparable to T cells from young individuals after stimulation by mitogens. To better characterize T cell impairment, we have focused on the in vitro T cell activation, analyzing by flow cytometry the activation molecules CD69 and CD71 on mitogen-stimulated lymphocytes from young and elderly subjects. The results show that the percentages of CD69+ and CD71 + T cells were significantly decreased in cultures from elderly subjects when compared to values obtained culturing cells from young individuals. The differences observed seem not due to differences in CD4 and CD8 rates in the "old' cells that underwent activation, since, following activation, the pattern of CD4 and CD8 phenotypes was the same in both groups of subjects. Signals from CD69 are relevant in controlling cytokine gene expression because its stimulation leads to interleukin-2 production and increases its receptor expression. The interaction of this cytokine with its cellular receptor is an essential requirement for T lymphocytes to express CD71 and to start proliferation. Thus, a key role in the age-associated impairment of T cell activation could be played by an ineffective modulation of CD69 expression suggesting a defect in the signal transduction pathway of the T cell receptor-CD3 complex in elderly.

Defective expression of the apoptosis-inducing CD95 (Fas/APO-1) molecule on T and B cells in IDDM

Triggering of CD95 (Fas/APO-1) cell surface receptors regulates the elimination of autoreactive T and B lymphocytes through a mechanism of cell suicide called apoptosis. Three different mutations involving CD95 or its ligand are responsible for induction of autoimmunity in susceptible mouse strains. To determine whether a defect involving the CD95 receptor is associated with human insulin-dependent diabetes mellitus (IDDM), we have studied the expression of CD95 on peripheral blood mononuclear cells from IDDM patients at different stages of the disease. Three-colour flow cytometry and mean fluorescence analysis showed that T and B lymphocytes from newly diagnosed IDDM and patients with long-standing disease, and subjects at high risk of developing the disease were highly defective in CD95 expression (p < 0.001), whereas monocytes from all the groups studied expressed normal amounts of CD95 molecules on their cell surface. T-cell subset analysis showed that the impairment of CD95 expression in IDDM patients and high-risk subjects involved both CD3+ CD4+ (p < 0.001) and CD3+ CD8+ cells (p range: < 0.01-0.001), suggesting that this alteration concerns both helper and cytotoxic T cells. Moreover, after activation in vitro with anti-CD3 monoclonal antibody, T cells from newly diagnosed IDDM patients maintained a reduced CD95 expression during the entire cell culture period (24-72 h) in comparison to the control population (p < 0.001). In conclusion, we found a reduced expression of the apoptosis-inducing CD95 receptor on T and B lymphocytes of individuals with clinical and preclinical IDDM. We hypothesize that this defective expression may impair the capacity of autoreactive lymphocytes to undergo CD95-mediated apoptosis, contributing to the lack of control on beta-cell specific B- and T-cell clones.

Low bcl-2 expression and increased spontaneous apoptosis in T-lymphocytes from newly-diagnosed IDDM patients

The bcl-2 gene product has been shown to regulate apoptotic cell death, and its dysregulation has been shown to induce several abnormalities in the immune system. No data exist regarding bcl-2 expression in autoimmune diseases, such as human insulin-dependent diabetes mellitus (IDDM). We investigated bcl-2 protein expression by testing T lymphocytes from 15 newly-diagnosed (< 3 weeks) IDDM patients in comparison to 10 age-matched control subjects. The expression of bcl-2 on CD3+ lymphocyte subsets was investigated after membrane permeabilization by two- or three-colour immunofluorescence. When the percentage and mean fluorescence intensity (MFI) of bcl-2+/CD3+ cells from normal individuals and patients were compared, we found that bcl-2 expression within the CD3+ and CD4+ CD45R0+ T-cell populations was reduced significantly in IDDM patients (46.8 +/- 15.4 vs 79.6 +/- 11.7; 25.7 +/- 3.8 vs 47.15 +/- 5.7, respectively; p < 0.001). To establish whether low bcl-2 expression in T cells from newly-diagnosed patients reflects their susceptibility to death by an apoptotic process, we also evaluated DNA staining with propidium iodide in CD3+ lymphocyte suspension after a (24-72 h) culture period (spontaneous apoptosis). We found that IDDM patients have higher levels of spontaneous apoptosis (mean +/- SEM: 24 h = 4.6 +/- 0.8; 48 h = 9.9 +/- 1; 72 h = 12.8 +/- 1.1) than control subjects (24 h = 1.8 +/- 0.4; 48 h = 4.6 +/- 0.4; 72 h = 5.7 +/- 0.3; p < 0.02-0.001). Our study suggests that recent onset IDDM is characterised by reduced bcl-2 expression, which in turn may be associated with the increased spontaneous apoptosis we observed.

T-cell activation in HLA-B8, DR3-positive individuals. Early antigen expression defect in vitro

The HLA-B8, DR3 haplotype is overrepresented in several autoimmune diseases, implying that genes predisposing to these disorders are linked to this haplotype. In the patients affected by these diseases, as well as in healthy HLA-B8, DR3 individuals, various dysfunctions reflecting an impairment of T-cell activation have been found. To better characterize T-cell impairment of HLA-B8, DR3-positive healthy individuals, we analyzed the surface expression of early (CD69) and late (CD71) activation phenotypes. MNC cultures were stimulated with PHA and used for T-cell phenotyping by flow cytometry analysis. The results showed that the percentage of CD69+ T cells was significantly decreased in MNC from HLA-B8, DR3+ subjects. This defect was detected in cell cultures from all subjects studied, but it attained significance only in females in the early hours after stimulation. The difference in CD69 expression between HLA-B8, DR3-positive individuals and -negative ones was not due to differences in CD4 and CD8 ratios in the HLA-B8, DR3 cells that underwent activation, as following activation the pattern of CD4 and CD8 antigen expression was the same in both groups of subjects. Concerning the late antigen CD71, no significant difference in percentage was observed between T lymphocytes from HLA-B8, DR3+ and HLA-B8, DR3- subjects at all the times studied. The analysis of the requirements for CD69 expression has suggested that sustained PKC activation and an increase of intracellular CA2+ could be responsible for TCR/CD3-mediated CD69 induction. Thus, present data suggest a defect in the signal transduction pathway of the TCR/CD3 complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Defective T cell receptor/CD3 complex signaling in human type I diabetes

The autoimmune process leading to the destruction of pancreatic beta-cells is mediated by T lymphocytes. Peripheral T cells from subjects with preclinical and clinical type I diabetes respond weakly in vitro to lectin stimulation. We, therefore, investigated in a group of newly diagnosed diabetic patients the presence of a defect in the signal transduction pathway of the T cell receptor (TcR)/CD3 complex. Following stimulation with anti-CD3-coupled beads, the proliferative response in diabetic T cells was significantly decreased in comparison with that from normal T cells. Interestingly, addition of either recombinant interleukin (IL)-2 or phorbol 12-myristate 13-acetate to the cell culture was able to completely restore impaired anti-CD3-induced proliferation in diabetic T cells, suggesting the presence of a defect through the TcR/CD3 pathway, located upstream of protein kinase C (PKC) activation and resulting in low IL-2 production and proliferation. Intracellular Ca2+ measurements by Fluo-3 labeling and flow cytometry analysis on diabetic and control T cells after anti-CD3 stimulation gave comparable results, indicating that this defect does not involve events leading to intracellular Ca2+ mobilization. In contrast, anti-CD3 stimulation of diabetic T cells resulted in a marked impairment of PKC translocation and CD69 antigen expression, as assessed by peptide substrate phosphorylation and by flow cytometry analysis, respectively. Taken together, our data clearly show the presence in individuals at the onset of the disease of an in vitro defect in the signal transduction pathway of the TcR/CD3 complex, resulting in ineffective PKC activation which is not able to induce normal IL-2 production and proliferation of diabetic T cells.