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C Boitard

Publications and source records attributed to C Boitard.

At least 19 recordsLinked to original sources
PubMed2006

Conditional and specific NF-kappaB blockade protects pancreatic beta cells from diabetogenic agents.

Type 1 diabetes is characterized by the infiltration of inflammatory cells into pancreatic islets of Langerhans, followed by the selective and progressive destruction of insulin-secreting beta cells. Islet-infiltrating leukocytes secrete cytokines such as IL-1beta and IFN-gamma, which contribute to beta cell death. In vitro evidence suggests that cytokine-induced activation of the transcription factor NF-kappaB is an important component of the signal triggering beta cell apoptosis. To study the in vivo role of NF-kappaB in beta cell death, we generated a transgenic mouse line expressing a degradation-resistant NF-kappaB protein inhibitor (DeltaNIkappaBalpha), acting specifically in beta cells, in an inducible and reversible manner, by using the tet-on regulation system. In vitro, islets expressing the DeltaNIkappaBalpha protein were resistant to the deleterious effects of IL-1beta and IFN-gamma, as assessed by reduced NO production and beta-cell apoptosis. This effect was even more striking in vivo, where nearly complete protection against multiple low-dose streptozocin-induced diabetes was observed, with reduced intraislet lymphocytic infiltration. Our results show in vivo that beta cell-specific activation of NF-kappaB is a key event in the progressive loss of beta cells in diabetes. Inhibition of this process could be a potential effective strategy for beta-cell protection.

Active Transport, Cell Nucleus↗
PubMed2005

Breast inflammatory gigantomastia in a context of immune-mediated diseases.

CONTEXT: Localized breast lesions have been described in lupic or diabetic patients. However, the description of breast gigantomastia in women presenting with autoimmune diseases has not been reported. SETTING: The study took place within the Department of Endocrinology and Reproductive Medicine, Necker Hospital, Paris, France. PATIENTS: We describe eight patients with inflammatory gigantomastia, occurring in a context of immune-mediated diseases: myasthenia, chronic arthritis, or thyroiditis. MAIN OUTCOME MEASURES: Together with hormonal, immunological, and breast magnetic resonance imaging (MRI) evaluation, breast histology enabled us to perform immunocytochemical and indirect immunofluorescence studies. Control sera were obtained from patients with (n = 10) and without (n = 7) antinuclear antibodies. RESULTS: Six of the eight patients developed gigantomastia either at puberty or during pregnancy. Neither a hormonal oversecretion nor a specific immunological pattern was observed. All patients except one presented antinuclear antibodies. Histological study revealed a diffuse, stromal hyperplasia and a severe atrophy of the lobules. A rarefaction of adipocytes was also noted, as previously suggested on MRI. There was a perilobular lymphocytic infiltrate made of CD3+ lymphocytes. Study of sera from five of six cases of gigantomastia showed a nuclear immunofluorescence pattern in normal mammary ductal and lobular glandular epithelium, as well as in kidney and intestine epithelial cells. In control sera, a nuclear signal was observed only when antinuclear antibodies were present. CONCLUSIONS: We suggest that breast tissue may be a target tissue in autoimmune diseases, this process being favored by the hormonal milieu. However, the precise mechanism of such association is not individualized. The fact that stromal hyperplasia is the main histological feature justifies the search for the involvement of growth factors in such a process.

Adolescent↗
PubMed2005

Transfer of diabetes from prediabetic NOD mice to NOD-SCID/SCID mice: association with pancreatic insulin content.

Splenocytes from prediabetic female NOD mice can transfer diabetes to NOD-SCID mice. Whereas the kinetics of disease transfer was shown to be a function of the age of donor splenocytes, information is scarce as to how the stage of autoimmune disease, as evaluated by pancreatic insulin content, is related to the diabetogenic potency of splenic T-cells. We therefore determined individual diabetes transfer times after an i. v. injection of splenocytes from prediabetic NOD mice of different ages into female NOD-SCID mice in relation to the diabetes incidence in NOD donor mice and their pancreatic insulin contents. Three groups (n = 8) of NOD mice aged 5, 11, and 17 weeks (wk) underwent splenectomy and hemipancreatectomy. After that, 10x10 (6) splenocytes either pooled from all donor NOD mice of the different age groups or individually from single donor mice were transferred to groups of four 6-week-old NOD-SCID mice, respectively, in two sets of experiments. Insulin was extracted from the resected hemipancreas, and the insulin content was determined by a RIA. Diabetes in the NOD-SCID cohort occurred after a mean time of 126 days after transfer of pooled splenocytes from 5-week-old NODs, after 68 days (transfer from 11-week-old NODs), and after a mean time of 43 days (transfer from 17-week-old NODs, 5 vs. 11 wk: p < 0.02, 11 vs. 17 wk: p < 0.001). Individual time to diabetes positively correlated with diabetes transfer times in NOD-SCID recipients (p < 0.0001) in the 17-week-old NOD mice, confirming previous diabetes transfer studies in hemi-pancreatectomized NOD mice. Furthermore, individual insulin concentrations in 17-week-old NOD mice also positively correlated to diabetes transfer times in recipient mice (p < 0.0001). No such correlations for these parameters were seen for the 5 and 11-week-old NOD mice (time to diabetes: 11 wk, p = 0.14, 5 wk, p = 0.75; insulin content: 11 wk, p = 0.81, 5 wk, p = 0.14). These data suggest that destructive T-cell activity increases during the course of islet autoimmunity. The immune response seems to be programmed for beta-cell destruction just before diabetes onset. This is the only time that pancreatic insulin content predicts the impending onset of diabetes.

Animals↗
PubMed2003

Destruction of conditional insulinoma cell lines in NOD mice: a role for autoimmunity.

AIMS/HYPOTHESIS: betaTC-tet (H2(k)) is a conditional insulinoma cell line derived from transgenic mice expressing a tetracycline-regulated oncogene. Transgenic expression of several proteins implicated in the apoptotic pathways increase the resistance of betaTC-tet cells in vitro. We tested in vivo the sensitivity of the cells to rejection and the protective effect of genetic alterations in NOD mice. METHODS: betaTC-tet cells and genetically engineered lines expressing Bcl-2 (CDM3D), a dominant negative mutant of MyD88 or SOCS-1 were transplanted in diabetic female NOD mice or in male NOD mice with diabetes induced by high-dose streptozotocin. Survival of functional cell grafts in NOD-scid mice was also analyzed after transfer of splenocytes from diabetic NOD mice. Autoreactive T-cell hybridomas and splenocytes from diabetic NOD mice were stimulated by betaTC-tet cells. RESULTS: betaTC-tet cells and genetically engineered cell lines were all similarly rejected in diabetic NOD mice and in NOD-scid mice after splenocyte transfer. In 3- to 6-week-old male NOD mice treated with high-dose streptozotocin, the cells temporarily survived, in contrast with C57BL/6 mice treated with high-dose streptozotocin (indefinite survival) and untreated 3- to 6-week-old male NOD mice (rejection). The protective effect of high-dose streptozotocin was lost in older male NOD mice. betaTC-tet cells did not stimulate autoreactive T-cell hybridomas, but induced IL-2 secretion by splenocytes from diabetic NOD mice. CONCLUSION/INTERPRETATION: The autoimmune process seems to play an important role in the destruction of betaTC-tet cells in NOD mice. Genetic manipulations intended at increasing the resistance of beta cells were inefficient. Similar approaches should be tested in vivo as well as in vitro. High dose streptozotocin influences immune rejection and should be used with caution.

Animals↗
PubMed2003

Alexithymia in insulin-dependent diabetes mellitus is related to depression and not to somatic variables or compliance.

OBJECTIVES: To assess the prevalence of alexithymia in insulin-dependent diabetic mellitus (IDDM) outpatients. To examine whether alexithymia is associated with diabetic somatic variables, depression, and compliance. METHOD: Our sample comprised 69 diabetic outpatients followed in a university hospital. We assessed the prevalence of alexithymia (26-item Toronto Alexithymia Scale, TAS-26) and the relationships among alexithymia, depression (13-item Beck Depression Inventory, BDI-13), somatic diabetic variables (glycosylated hemoglobin, number of mild or severe hypoglycemia, somatic complications), and compliance (observer-rater scale completed by diabetologist). RESULTS: The prevalence of alexithymia in IDDM patients was low (14.4%). Alexithymia and depression, as measured by TAS-26 and BDI-13 scores, respectively, correlated with each other. Alexithymia was not correlated with glycemic control, somatic complications, or compliance. CONCLUSION: In our sample, alexithymia was related to depression and not to somatic factors or compliance.

Adult↗
PubMed2003

Passive transfer of flt-3L-derived dendritic cells delays diabetes development in NOD mice and associates with early production of interleukin (IL)-4 and IL-10 in the spleen of recipient mice.

CD11c+/CD11b+dendritic cells (DC) with high levels of major histocompatibility complex (MHC) class II and co-stimulatory molecules have been derived from spleen cells cultured with granulocyte-macrophage colony stimulating factor (GM-CSF) + flt-3L + interleukin (IL)-6 (flt-3L-DC). Investigating in vivo the function of DC in non-obese diabetic mice (NOD), we showed that a single injection of this in vitro-derived subset of DC prevents the development of diabetes into prediabetic female mice. In contrast, DC derived from bone marrow cells cultured with GM-CSF + IL-4 [bone marrow (BM)-DC] induced no protection. Moreover, protection against diabetes following injection of flt-3L-DC was associated with IL-4 and IL-10 production in the spleen and the pancreatic lymph nodes of recipient mice, indicating that this DC population is able to polarize the immune response towards a Th2 pathway. As we shown previously, NOD BM-DC exhibit an enhanced capacity to produce IL-12p70 in response to lipopolysaccharide (LPS) and anti-CD40 stimulation compared to BM-DC from control mice. In contrast, NOD flt-3L-DC, as their control mouse counterpart, produced no IL-12p70 to these stimuli. Our findings show that a subset of DC, characterized by a mature phenotype and the absence of IL-12p70 production can be derived from NOD mouse spleen favouring IL-4 and IL-10 regulatory responses and protection from diabetes development.

Animals↗
PubMed2002

Insulin secretion in type 2 diabetes: clinical aspects.

Type 2 diabetes is a complex disease that involves insulin secretion abnormalities and defects in the action of insulin on its target tissues. Insulin resistance alone is not sufficient to lead to type 2 diabetes in the absence of a beta-cell defect. Patients with impaired glucose tolerance or in the early stages of type 2 diabetes always present with beta-cell secretion defects. In the early stages of type 2 diabetes, abnormalities in the physiological biphasic insulin secretion are already encountered, with very often a loss of the first phase insulin secretion. In this review, we discuss the methods to evaluate beta-cell function and their limitations, then their relationship with genetic knowledge. Currently, it is still impossible, in the absence of biological parameters characterizing the etiology of type 2 diabetes, to precisely correlate the insulin-secretion tests with the diagnosis of the disease. Autoimmune type 1 diabetes appears a useful model to study type 2 diabetes. The availability of individual genetic mapping will permit a reliable clinical evaluation and interpretation of tests of insulin secretion in the future.

Blood Glucose↗
PubMed2001

Three loci on mouse chromosome 6 influence onset and final incidence of type I diabetes in NOD.C3H congenic strains.

The development of insulin-dependent diabetes mellitus in both human and mouse is dependent on the interaction between genetic and environmental factors. The analysis of newly created NOD.C3H congenic strains for spontaneous and cyclophosphamide-induced diabetes has allowed the definition of three controlling genetic loci on mouse chromosome 6. A NOD-derived susceptibility allele at the Idd6 locus strongly influences the onset of diabetes in spontaneous diabetes. A NOD-derived resistance allele at the Idd19 locus affects the final diabetes incidence observed in both models, while a novel locus, provisionally termed Idd20, appears to control Idd19 in an epistatic manner. Decreased diabetes incidence is observed in CY-induced diabetes when Idd20 is homozygous for the C3H allele, while heterozygosity is associated with an increase in diabetes incidence. The Idd20, Idd19, and Idd6 candidate regions fall respectively within genetically defined intervals of 4, 7, and 4.5 cM on mouse chromosome 6. From our YAC contig, Idd6 would appear to localize within a ca. 1.5-Mb region on distal chromosome 6.

Age Factors↗
PubMed2001

A common stromal cell-derived factor-1 chemokine gene variant is associated with the early onset of type 1 diabetes.

Type 1 diabetes results from the autoimmune destruction of pancreatic beta-cells. Although the disease shows a strong association with HLA class II alleles, other genes may influence the initiation or the rate of progression of the autoimmune process. The recruitment of mononuclear cells within the islets of Langerhans is a critical step in the pathogenesis of the disease. Because chemokines are cytokines that promote migration of mononuclear cells, we hypothesized that polymorphisms in chemokine receptor or chemokine genes, CCR5 and SDF1, may be involved in susceptibility to or clinical expression of type 1 diabetes. The frequencies of the CCR5-delta32 and SDF1-3'A (801G-->A in the 3' untranslated region) variants were similar in 208 unrelated Caucasian patients with type 1 diabetes and in 120 Caucasian control subjects. They were not modified after stratification for the predisposing HLA-DR3 and -DR4 haplotypes. However, the SDF1-3'A variant was strongly associated with early onset (< 15 years) of the disease (odds ratio 2.6, P = 0.0019). On average, the presence of the SDF1-3'A allele was associated with a 5-year reduction in the age at onset of diabetes (P = 0.0067). Our results suggest that stromal cell-derived factor-1 may be implicated in the aggressiveness of the autoimmune process leading to type 1 diabetes. These preliminary data require replication in other populations.

3' Untranslated Regions↗
PubMed2001

Heterogeneity of fetal growth in type 1 diabetic pregnancy.

OBJECTIVE: To investigate the frequency of macrosomia in an homogeneous cohort of type 1 diabetic mothers and to analyze the influence of maternal factors and glycemic control on the incidence of fetal macrosomia. MATERIAL AND METHODS: Fifty-five consecutive type 1 diabetic first-pregnancies were prospectively studied. Macrosomia was defined by a ponderal index above the 90(th) percentile. Venous cord blood levels of insulin, C peptide and leptin were measured at delivery. The influence of HbA1c levels and other maternal variables on the occurrence of macrosomia and on the ponderal index was assessed using a stepwise regression logistic model. RESULTS: The mean (+/- SD) birth weight was 3482 (+/- 497) g at 37.4 +/- 1.0 weeks gestation. Macrosomia occurred in 29 cases (53.7%). Fetal insulin, C peptide and leptin levels were significantly higher in macrosomic than in non macrosomic infants. Maternal age, duration of diabetes, pregravid body mass index, parity, weight gain during pregnancy, presence of a microangiopathy, nephropathy, smoking habits, gestational hypertension or preeclampsia, and HbA1c levels throughout pregnancy did not differed between mothers of macrosomic and non macrosomic infants. In the stepwise analysis none of these covariates was explanatory of the ponderal index. CONCLUSIONS: The frequency of macrosomia remains very high in infants of type 1 diabetic mothers despite a reasonable degree of glycemic control. The variability of the fetal growth response to mild hyperglycemia prompts for the identification of other factors involved in the modulation of fetal growth.

Adult↗
PubMed2000

Oral insulin administration and residual beta-cell function in recent-onset type 1 diabetes: a multicentre randomised controlled trial. Diabète Insuline Orale group.

BACKGROUND: Oral administration of autoantigens can slow the progression of beta-cell destruction in non-obese diabetic mice. We investigated whether oral administration of recombinant human insulin could protect residual beta-cell function in recent-onset type 1 diabetes. METHODS: We enrolled 131 autoantibody-positive diabetic patients aged 7-40 years within 2 weeks of diagnosis (no ketoacidosis at diagnosis, weight loss <10%, polyuria for <6 weeks). They were randomly assigned 2.5 mg or 7.5 mg oral insulin daily or placebo for 1 year, in addition to subcutaneous insulin therapy. Serum C-peptide concentrations were measured in the fasting state and after stimulation, to assess beta-cell function. Autoantibodies to beta-cell antigens were assayed. Analyses were by intention to treat. FINDINGS: Baseline C-peptide and haemoglobin A1c concentrations were similar in the three groups. During follow-up, there were no differences between the groups assigned 2.5 mg or 7.5 mg oral insulin or placebo in subcutaneous insulin requirements, haemoglobin A1c concentrations, or measurements of fasting (mean at 12 months 0.18 [SD 0.17], 0.17 [0.17], and 0.17 [0.12] nmol/L) or stimulated C-peptide concentrations (glucagon-stimulated 0.39 [0.38], 0.37 [0.39], and 0.33 [0.24] nmol/L; meal-stimulated 0.72 [0.60], 0.49 [0.49], and 0.57 [0.51 nmol/L]. Neither age nor C-peptide concentration at entry influenced treatment effects. No differences were seen in the time-course or titres of antibodies to insulin, glutamic acid decarboxylase, or islet antigen 2. INTERPRETATION: At the doses used in this trial, oral administration of insulin initiated at clinical onset of type 1 diabetes did not prevent the deterioration of beta-cell function.

Administration, Oral↗
PubMed2000

Effects of prolonged administration of ultralente insulin on fasting and postbreakfast beta-cell function in normal adults.

Treatment with small doses of subcutaneous insulin is being investigated as a possible approach to prevent type 1 diabetes in humans. The mechanism of prophylactic insulin therapy could involve the inhibition of beta-cell secretory activity and/or the initiation of an active immunoregulatory process. To evaluate the pure metabolic effect of exogenous insulin, the present study assessed whether daily subcutaneous administration of ultralente insulin alters beta-cell function in normal adults. Fourteen healthy adults were randomized to receive 0.2 U/kg x d ultralente insulin (Ultratard; Novo Nordisk, Bagsvaerd, Denmark) or placebo subcutaneously once daily for 30 days. Plasma glucose, C-peptide, and insulin concentrations were measured in the fasting state and 1 hour after a standardized breakfast, during treatment and during a recovery period of 10 days. Insulin administration induced a 15% to 40% decrease of fasting plasma C-peptide. In contrast, postbreakfast plasma C-peptide increased by 40% to 90% in subjects receiving insulin. Fasting and postbreakfast C-peptide concentrations were significantly different between groups during the injection period after adjustment for baseline concentrations (P < .05, ANOVA with repeated measures). These alterations disappeared 3 days after cessation of insulin treatment. The present regimen of exogenous insulin alters endogenous insulin secretion in normal subjects. Instead of the expected beta-cell rest, the effect appeared to be dual, with insulin secretion decreasing in the basal state and increasing after meals.

Adult↗
PubMed2000

Clinical characteristics of type 2 diabetes in patients with mutations of HFE.

Genetic hemochromatosis (GH) is associated with two mutations of the HFE gene (Cys282Tyr and His63Asp). Heterozygosity for GH is associated with a mild increase in iron metabolism parameters, and increased iron stores are associated with abnormal glucose tolerance and decreased insulin sensitivity in the general population. We have previously shown that the frequency of the two HFE mutations is not increased in patients with type 2 diabetes. However, to assess whether the presence of HFE mutations modulates the clinical presentation of type 2 diabetes, we studied the clinical characteristics and iron metabolism indexes according to the presence of the two mutations in 266 patients with type 2 diabetes. The Cys282Tyr mutation and the His63Asp mutation were present in 9. 8% and 26% of the patients, respectively. Serum iron, transferrin saturation and ferritin concentrations were significantly increased in patients expressing either HFE mutations, compared to those without any mutation. There was no difference in the clinical characteristics in the two groups except that obesity was significantly less frequent in the patients with at least one mutation than in those without any mutation (27.6% vs 42.8%, p=0.02). This finding suggests that, in the absence of obesity, HFE mutations, through the insulin resistance associated with the increase in iron stores, may contribute to the onset of type 2 diabetes.

Amino Acid Substitution↗
PubMed1999

T-cell response to proinsulin and insulin in type 1 and pretype 1 diabetes.

Insulin-dependent diabetes mellitus (IDDM) results from the selective destruction of pancreatic beta cells by a T cell-mediated autoimmune process. Insulin and proinsulin are the only known beta cell-specific autoantigens. Using short-term cultures of freshly isolated peripheral blood mononuclear cells, we evaluated T-cell responses to proinsulin and to insulin in IDDM patients and individuals at risk for IDDM. A proliferative T-cell response to proinsulin was observed in only 2 of 26 recent-onset IDDM subjects and 2 of 12 long-standing IDDM subjects and was associated with a proliferative response to insulin. In contrast, 5 of 13 islet cell autoantibody-positive first-degree relatives of IDDM patients showed a proliferative response to proinsulin alone, 3 of 13 to insulin alone, and 1 of 13 to both insulin and proinsulin. Overall, 9 of 13 ICA-positive first-degree relatives responded to either proinsulin or insulin. We observed an inverse relationship between antiinsulin antibodies and T-cell responses to insulin in ICA-positive first-degree relatives but not in long-standing IDDM patients. Our data indicate that proinsulin is a major antigen in IDDM and, further, illustrate the difference between the autoimmune response to insulin and the immune response to exogenous insulin.

Adolescent↗
PubMed1999

Absence of significant Th2 response in diabetes-prone non-obese diabetic (NOD) mice.

Accumulating evidence suggests that Th1 T cells play a pivotal role in the development of autoimmune diabetes. Conversely, promoting a Th2 response inhibits disease progression. However, it has not been determined whether Th2 cells are regulatory T cells that fail at the time of diabetes development in naive non-diabetic NOD mice. Therefore, in order to evaluate cytokine secretion by spleen and islet infiltrating T cells in NOD mice at different stages of the autoimmune process, we developed an ELISPOT assay that detects IL-2, IL-4, and interferon-gamma (IFN-gamma) secretion in vitro at the single-cell level. We showed that, whatever the age considered, IFN-gamma is predominantly secreted, and that no IL-4-secreting cells are detected in the islets of male and female NOD mice. Spleen cells from 8-week-old female NOD mice, which include regulatory suppressor T cells, do not secrete IL-4, either upon presentation of islet cell antigens in vitro, or after transfer in vivo, but do secrete IFN-gamma. IFN-gamma secretion by T cells from diabetic mice results from CD4 but not CD8 T cells in transfer experiments into NOD/severe combined immunodeficient (SCID) recipients. These results suggest that (i) detection of regulatory CD4 T cells in NOD mice is not paralleled by a Th2 response; (ii) beta cell destruction does not depend on a switch from a Th2 to a Th1-type response; and (iii) CD8 T cells do not participate in induction of diabetes by secreting IFN-gamma.

Animals↗