PubMed Health⌕ Search

Biomedical subjects

C Boitard

Publications and source records attributed to C Boitard.

At least 19 recordsLinked to original sources
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

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↗
PubMed1998

Identification of mimicry peptides based on sequential motifs of epitopes derived from 65-kDa glutamic acid decarboxylase.

Insulin-dependent diabetes mellitus (IDDM) is an autoimmune disease with a predominantly non-hereditary etiology that results in a destruction of pancreatic beta cells by autoaggressive T lymphocytes. Neither the mechanism of initial stimulation of these T cells nor the nature of the environmental factors implicated in the disease have so far been identified. However, both issues are taken into account by the hypothesis of initial T cell activation by viral or bacterial mimicry peptides with sequence similarities to pancreatic self antigens. We determined sequential epitope motifs to search for mimicry peptides stimulating T cell lines specific for two epitopes derived from the IDDM autoantigen 65-kDa glutamic acid decarboxylase (GAD65). These were GAD65 (88-99), presented by HLA-DRB1*0101, and GAD65 (248-257), presented by HLA-DRB5*0101. T cell stimulation by peptides with substitutions in HLA anchor or T cell contact positions was analyzed to establish degenerate epitope motifs for database searching. Out of 28 tested candidate mimicry peptides derived from bacterial, viral and human proteins, 3 stimulated T cell lines and a T cell clone specific for epitope GAD65 (248-257). Our results demonstrate that mono- and polyclonal GAD65-specific T cells from IDDM patients can be stimulated by viral and bacterial peptides with little apparent sequence homology with autoantigenic epitopes. Moreover, in a synopsis with related published studies, our findings suggest that simple degenerate search motifs comprising principal T cell contacts plus HLA class II binding motifs may suffice to identify most mimicry peptides.

Adult↗
PubMed1998

Low dose linomide in Type I juvenile diabetes of recent onset: a randomised placebo-controlled double blind trial.

The quinoline-3-carboxamide, linomide, protects non-obese diabetic mice from diabetes. The effects of linomide on insulin needs and beta cell function were studied in recent juvenile Type I diabetes in a double-blind trial. Patients with recent onset diabetes were randomly assigned to treatment with a fixed dose of 2.5 mg linomide (42 patients) or placebo (21 patients) for 1 year, in addition to insulin and diet. Glycated haemoglobin was 10-15% lower at 9 months (p = 0.003) and 12 months (p < 0.05) in the linomide group. The insulin dose was 32-40% smaller in the linomide group at 3 (p < 0.03), 6 (p < 0.02), 9 (p < 0.001) and 12 months (p = 0.01). Insulin doses correlated negatively with C peptide values (p = 0.001-0.002). The trend for higher C peptide values in the linomide group did not reach significance. In a post hoc subgroup analysis performed in 40 patients (25 from the linomide group and 15 from the placebo group) who still had detectable residual beta cell function at entry, linomide was associated with 45-59% higher C peptide value at 6 months (p < 0.05), 9 months (p < 0.05) and 12 months (p < 0.05). The main adverse effects of linomide were mild transitory anaemia (45 vs 10% in the linomide and placebo groups), thrombocytopenia (24 vs 10%), and mild joint discomfort (45 vs 5%) with no clinical signs. In conclusion, low-dose linomide reduced the insulin needs in patients with juvenile Type I diabetes of recent onset and improved beta cell function in patients who still had detectable beta cell function at entry. These results support further clinical and experimental studies to define the effects of linomide in Type I diabetes provided the safety of linomide is reliably established.

Adjuvants, Immunologic↗
PubMed1998

Peptide specificity of high-titer anti-glutamic acid decarboxylase (GAD)65 autoantibodies.

To study systematically the linear epitope specificity of anti-glutamic acid decarboxylase (GAD) autoantibodies associated with insulin-dependent diabetes mellitus (IDDM), we produced 93 overlapping 12-residue synthetic peptides derived from the sequence of the human GAD65 protein and covering the entire length of the protein. These peptides were used as antigens in an enzyme immunoassay to screen the sera from 10 IDDM patients, all of which contained at high level autoantibodies directed against GAD65. Three out of ten (30%) IDDM patients had antibodies that reacted with one or more of the synthetic peptides. Two of the peptide-reactive IDDM sera, which also bound denatured recombinant GAD65 on western blots, had the highest titers of anti-GAD antibodies in ELISA assay. Moreover, the anti-GAD antibodies-GAD complexes formed with these sera were characterized by low dissociation rates, indicative of their good stability. A fine specificity analysis, using analogs of antigen peptide 1 (residues 1-12), allowed us to identify the residues at positions 5-9 (GSGFW) as critical for antibody recognition.

Antibody Specificity↗
PubMed1998

Major histocompatibility class II genes polymorphism in insulin dependent diabetes mellitus with or without associated thyroid autoimmunity.

Insulin dependent diabetes mellitus (IDDM) is sometimes associated with extrapancreatic organ-specific autoimmune diseases, but whether this phenotype results from a peculiar genetic profile is still unclear. The allelic distribution of the major histocompatibility complex (MHC) class II genes (HLA-DRB1, DQA1, DQB1 and TAP) was analysed in 143 patients with IDDM alone by comparison with 82 IDDM patients with autoimmune thyroid disease (IDDM/AITD). The frequency of the DQB1*0301 IDDM-protective phenotype seemed to be lower in IDDM than in IDDM/AITD patients (16.8% vs 30.5% respectively, p = 0.02). By contrast, the frequency of the DRB1*04-DQB1*0302 IDDM-predisposing phenotype was higher in IDDM than in IDDM/AITD patients (91.3% vs 76.1% of DR4-positive patients respectively, p = 0.007), but these differences were not significant after correcting the p values, except in the case of the DRB1*0405-DQB1*0302 combination (21.3% vs 2.4% of DR4-positive patients, Pc = 0.05). Furthermore, all differences disappeared when patients were matched for age at IDDM-onset. Our data do not long give support for a particular role of MHC class II genes in favouring the occurrence of thyroid autoimmunity in IDDM patients, but rather suggest that some class II alleles or residues might determine the rapidity of progression to IDDM in genetically susceptible individuals. The involvement of non-MHC genes and/or environmental factors remains to be determined.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1998

HLA class II-associated predisposition to insulin-dependent diabetes mellitus in a Polish population.

Susceptibility and resistance to insulin-dependent diabetes mellitus (IDDM) are strongly associated with alleles of HLA class II DR and DQ genes. We have studied HLA DRB1, DQA1, DQB1 allele and haplotype distribution in 152 IDDM children and 103 unrelated healthy individuals from the region of Lodz in central Poland by the polymerase chain reaction and hybridisation with allele-specific oligonucleotide probes. The DRB1*04 allele showed the strongest association with IDDM in the Polish population (OR = 3.87). The DRB1*03 allele was also associated with predisposition to the disease (OR = 3.25), particularly in DR3/4 heterozygous individuals (OR = 14.47). Among DR4 subtypes, DRB1*0401 was the most frequent both in patients and controls, whereas DRB1*0403 was rarely observed in patients and conferred a significant protection from IDDM. The DRB1*04-DQA1*0301-DQB1*0302 haplotype conferred the highest risk to develop IDDM. The presence of DRB1*0401 on this haplotype reinforced the disease risk whereas DRB1*0403 had a dominant protective effect even in the presence of the predisposing DQB1*0302 allele (OR = 0.24). The DRB1*1501-DQA1*0102-DQB1*0602 haplotype conferred a dominant protective effect (OR = 0.04). The different behaviour of the DRB1*04-DQB1*0302 haplotypes in conferring IDDM risk confirms that DRB1 by itself is strongly associated with IDDM independently from DQB1, with DRB1*0401 being a high frequency/moderate risk allele, and DRB1*0403 a high frequency/low risk allele in the Polish population.

Adolescent↗
PubMed1998

HLA class II allele and haplotype distribution in a population from central Poland.

We have studied the distribution of HLA DRB1, DQA1, DQB1 alleles and haplotypes in a sample of 103 unrelated healthy individuals from the region of Lodz in central Poland by the polymerase chain reaction and hybridization with allele-specific oligonucleotide probes (PCR-SSO). DRB1*0101, DRB1*07, DRB1*1501, DRB1*03 and DRB1*11 were the most frequent alleles at the DRB1 locus. The DRB1*04 group was observed at a high frequency, but only five out of the 19 DR4 subtypes tested were observed. The most frequent was DRB1*0401, followed by DRB1*0403, DRB1*0402, DRB1*0407 and DRB1*0417. Eight DQA1 alleles were found in this Polish population, among which DQA1*0501, DQA1*0101 and DQA1*0102 were the most frequent. At the DQB1 locus 13 alleles were found. Among them, four were present with frequencies above 10%: DQB1*0201, DQB1*0301, DQB1*0501 and DQB1*0602. Our results underline significant differences between the population of central Poland and populations of neighbouring countries such as Germany, Ukraine and the Czech Republic. This study will serve as a reference for further anthropological studies, as well as studies of associations between HLA and disease.

Alleles↗
PubMed1998

Evidence for the presence of insulin-dependent diabetes-associated alleles on the distal part of mouse chromosome 6.

Type 1 diabetes (IDDM) is a complex disorder with multifactorial and polygenic etiology. A genome-wide screen performed in a BC1 cohort of a cross between the nonobese diabetic (NOD) mouse with the diabetes-resistant feral strain PWK detected a major locus contributing to diabetes development on the distal part of chromosome 6. Unlike the majority of other Idd loci identified in intraspecific crosses, susceptibility is associated with the presence of the PWK allele. Genetic linkage analysis of congenic lines segregating PWK chromosome 6 segments in a NOD background confirmed the presence of the Idd locus within this region. The genetic interval defined by analysis of congenic animals showed a peak of significant linkage (P = 0.0005) centered on an approximately 9-cM region lying between D6Mit11 and D6Mit25 genetic markers within distal mouse chromosome 6. [Genetic markers polymorphic between the NOD and PWK strains are available as a supplement at http://www.genome.org]

Alleles↗
PubMed1998

Eating disorders and insulin-dependent diabetes mellitus (IDDM): relationships with glycaemic control and somatic complications.

This study was designed to assess (by means of a diagnostic interview based on DSM-III-R criteria) the prevalence of eating disorders in 69 insulin-dependent diabetic (IDDM) out-patients, and the relationship with somatic risks. We found no cases of anorexia nervosa or bulimia nervosa, current or lifetime, in male patients with IDDM. No female patients with IDDM had anorexia, and 4.8% had current and lifetime bulimia. Eating disorders not otherwise specified (bulimic type) were significantly more frequent in women than in men (lifetime incidence 43% vs. 21%; current incidence 33% vs. 5%), and generally occurred after the onset of IDDM. Self-reports of bulimic behaviours according to the Bulimic Investigatory Test of Edinburgh (BITE) were associated with high levels of glycosylated haemoglobin. There was no association between eating disorders (current or lifetime), with somatic complications being more likely to be explained by a long duration of illness and impaired glycaemic control.

Adult↗