Characterization of resident lymphocytes in human pancreatic islets.

The current view of type 1 diabetes (T1D) is that it is an immune-mediated disease where lymphocytes infiltrate the pancreatic islets, promote killing of beta cells and cause overt diabetes. Although tissue resident immune cells have been demonstrated in several organs, the composition of lymphocytes in human healthy pancreatic islets have been scarcely studied. Here we aimed to investigate the phenotype of immune cells associated with human islets of non-diabetic organ donors. A flow cytometry analysis of isolated islets from perfused pancreases (n = 38) was employed to identify alpha, beta, T, natural killer (NK) and B cells. Moreover, the expression of insulin and glucagon transcripts was evaluated by RNA sequencing. Up to 80% of the lymphocytes were CD3+ T cells with a remarkable bias towards CD8+ cells. Central memory and effector memory phenotypes dominated within the CD8+ and CD4+ T cells and most CD8+ T cells were positive for CD69 and up to 50-70% for CD103, both markers of resident memory cells. The frequency of B and NK cells was low in most islet preparations (12 and 3% of CD45+ cells, respectively), and the frequency of alpha and beta cells varied between donors and correlated clearly with insulin and glucagon mRNA expression. In conclusion, we demonstrated the predominance of canonical tissue resident memory CD8+ T cells associated with human islets. We believe that these results are important to understand more clearly the immunobiology of human islets and the disease-related phenotypes observed in diabetes.

Altered regulatory T cell phenotype in latent autoimmune diabetes of the adults (LADA).

Latent autoimmune diabetes of the adults (LADA) accounts for up to 12% of all patients with diabetes. Initially the disease resembles type 2 diabetes (T2D); however, the typical presence of ß cell autoantibodies indicates an autoimmune basis of LADA. While dysfunctional regulatory T cells (Tregs ) have been implicated in autoimmune diabetes, these cells have been scarcely studied in LADA. The aim of this study was to investigate the frequency and phenotype of circulating Tregs in LADA patients early during disease progression. Flow cytometric analysis was performed on whole blood and peripheral mononuclear cells (PBMC) from patients diagnosed with LADA prior to insulin deficiency (n = 39) and from healthy volunteers (n = 20). Overall, we found the frequency and activation status of peripheral putative Tregs to be altered in LADA patients compared to healthy controls. While total T cells and CD4(+) T cells expressing high levels of CD25 (CD4(+) CD25(hi) ) were unchanged, the frequency and total numbers of CD4(+) T cells expressing an intermediate level of CD25 (CD4(+) CD25(int) ) were decreased in LADA patients. Interestingly, the expression of the Treg -specific marker forkhead box protein 3 (FoxP3), as well as the activation and memory makers CD69, cytotoxic T lymphocyte associated antigen 4 (CTLA-4), CCR4 and CD45RO were increased in CD4(+) CD25(+) T cells of the patients. Our data depict phenotypical changes in T cells of LADA patients that may reflect a derangement in peripheral immune regulation contributing to the slow process leading to insulin-dependent diabetes in these patients.

Immunological alteration and changes of gut microbiota after dextran sulfate sodium (DSS) administration in mice.

Ulcerative colitis (UC) is characterized by chronic inflammation of the colonic mucosa. Administration of dextran sulfate sodium (DSS) to animals is a frequently used model to mimic human colitis. Deregulation of the immune response to the enteric microflora or pathogens as well as increased intestinal permeability have been proposed as disease-driving mechanisms. To enlarge the understanding of the pathogenesis, we have studied the effect of DSS on the immune system and gut microbiota in mice. Intestinal inflammation was verified through histological evaluation and myeloperoxidase activity. Immunological changes were assessed by flow cytometry in spleen, Peyer's patches and mesenteric lymph nodes and through multiplex cytokine profiling. In addition, quantification of the total amount of bacteria on colonic mucosa as well as the total amount of lactobacilli, Akkermansia, Desulfovibrio and Enterobacteriaceae was performed by the use of quantitative PCR. Diversity and community structure were analysed by terminal restriction fragment length polymorphism (T-RFLP) patterns, and principal component analysis was utilized on immunological and T-RFLP patterns. DSS-induced colitis show clinical and histological similarities to UC. The composition of the colonic microflora was profoundly changed and correlated with several alterations of the immune system. The results demonstrate a relationship between multiple immunological changes and alterations of the gut microbiota after DSS administration. These data highlight and improve the definition of the immunological basis of the disease and suggest a role for dysregulation of the gut microbiota in the pathogenesis of colitis.

Antibiotic treatment of pregnant non-obese diabetic mice leads to altered gut microbiota and intestinal immunological changes in the offspring.

The intestinal microbiota is important for tolerance induction through mucosal immunological responses. The composition of the gut microbiota of an infant is affected by environmental factors such as diet, disease and antibiotic treatment. However, already in utero, these environmental factors can affect the immunological development of the foetus and influence the future gut microbiota of the infant. To investigate the effects of antibiotic treatment of pregnant mothers on the offspring's gut microbiome and diabetes development, we treated non-obese diabetic (NOD) mice with a cocktail of antibiotics during gestation and the composition of the gut microbiota, diabetes incidence and major gut-related T lymphocyte populations were investigated in the offspring. We observed a persistent reduction in the general diversity of the gut microbiota in the offspring from NOD mothers treated with antibiotics during gestation compared with offspring from control mothers. In addition, by clustering the present bacterial taxa with principal component analysis, we found a differential clustering of gut microbiota in the offspring from NOD mothers treated with antibiotics during gestation compared with offspring from control mothers. Offspring from NOD mothers treated with antibiotics during gestation also showed some immunological alterations in the gut immune system, which could be related to the diversity of the gut microbiome and influence modulation of diabetes development at 20 weeks. Our data point out maternal derangement of the intestinal microbiota as a potential environmental risk factor for T1D development.

Comparison of cryopreservation methods on T-cell responses to islet and control antigens from type 1 diabetic patients and controls.

BACKGROUND: Type 1 diabetes (T1D) is a cell-mediated autoimmune disease characterized by destruction of the pancreatic islet cells. The use of cryopreserved cells is preferable to the use of freshly isolated cells to monitor clinical trials to decrease assay and laboratory variability. METHODS: The T-Cell Workshop Committee of the Immunology of Diabetes Society compared two widely accepted T-cell freezing protocols (warm and cold) to freshly isolated peripheral blood mononuclear cells from patients with T1D and controls in terms of recovery, viability, cell subset composition, and performance in functional assays currently in use in T1D-related research. Nine laboratories participated in the study with four different functional assays included. RESULTS: The cold freezing method yielded higher recovery and viability compared with the warm freezing method. Irrespective of freezing protocol, B cells and CD8+ T cells were enriched, monocyte fraction decreased, and islet antigen-reactive responses were lower in frozen versus fresh cells. However, these results need to take in to account that the overall response to islet autoantigens was low in some assays. CONCLUSIONS: In the current study, none of the tested T-cell functional assays performed well using frozen samples. More research is required to identify a freezing method and a T-cell functional assay that will produce responses in patients with T1D comparable to responses using fresh peripheral blood mononuclear cells.

Maternal autoimmune thyroid disease and the fetal immune system.

OBJECTIVE: Several studies indicate that in utero exposure to maternal autoimmune diseases and transplacental passage of autoantibodies affect the risk of autoimmunity in the offspring, e. g., maternally derived GAD65 autoantibody correlates with decreased risk of type 1 diabetes, whereas thyroid peroxidase autoantibody (TPOAb) positivity at birth is associated with increased incidence of autoimmune thyroid disease later in life. The aim of this study was to identify immunological changes in children born to mothers with thyroid autoimmunity that may be related to in utero exposure to autoantibodies. DESIGN AND METHOD: Open label prospective analysis of cord blood lymphocytes and serum cytokines by Flow Cytometry in children born to mothers with autoimmune thyroiditis (AIT) (n=31) and to healthy mothers (n=76) and titers of thyroid autoantibodies were determined in cord blood and in maternal peripheral blood at delivery. RESULTS: We found an increase (almost 30%) in the frequency of cord blood natural killer (NK) cells (p=0.0016) and a minor increase in the subset of T cells expressing NK markers (p=0.028), in children born to AIT mothers. There were no detectable differences in the phenotype or frequency of cord blood memory/activated T cells, including CD4 (+)CD25 (+) T cells, between the 2 groups. The levels of pro-inflammatory cytokines TNF-α, IL-10, IL-12p70, IFN-γ and IL-1ß were significantly decreased in offspring of AIT mothers as compared to healthy controls. CONCLUSIONS: Maternal thyroid autoimmunity and transplacental passage of autoantibodies against thyroid antigens may affect the generation or expansion of cells with NK activity and the secretion of inflammatory cytokines.

Isolation and preservation of peripheral blood mononuclear cells for analysis of islet antigen-reactive T cell responses: position statement of the T-Cell Workshop Committee of the Immunology of Diabetes Society.

Autoimmune T cell responses directed against insulin-producing ß cells are central to the pathogenesis of type 1 diabetes (T1D). Detection of such responses is therefore critical to provide novel biomarkers for T1D 'immune staging' and to understand the mechanisms underlying the disease. While different T cell assays are being developed for these purposes, it is important to optimize and standardize methods for processing human blood samples for these assays. To this end, we review data relevant to critical parameters in peripheral blood mononuclear cell (PBMC) isolation, (cryo)preservation, distribution and usage for detecting antigen-specific T cell responses. Based on these data, we propose recommendations on processing blood samples for T cell assays and identify gaps in knowledge that need to be addressed. These recommendations may be relevant not only for the analysis of T cell responses in autoimmune disease, but also in cancer and infectious disease, particularly in the context of clinical trials.

Current approaches to measuring human islet-antigen specific T cell function in type 1 diabetes.

Type 1 diabetes (T1D) is an autoimmune disease caused by the T cell-mediated destruction of the pancreatic insulin-producing beta cells. Currently there are no widely accepted and standardized assays available to analyse the function of autoreactive T cells involved in T1D. The development of such an assay would greatly aid efforts to understand the pathogenesis of T1D and is also urgently required to guide the development of antigen-based therapies intended to prevent, or cure, T1D. Here we describe some of the assays used currently to detect autoreactive T cells in human blood and review critically their strengths and weaknesses. The challenges and future prospects for the T cell assays are discussed.

Changes in GAD65Ab-specific antiidiotypic antibody levels correlate with changes in C-peptide levels and progression to islet cell autoimmunity.

CONTEXT: The previously reported absence of 65-kDa glutamate decarboxylase antibody (GAD65Ab)-specific antiidiotypic antibodies (anti-Id) in type 1 diabetes (T1D) patients at clinical onset could be due to an inability to mount an antibody response to GAD65Ab or a longitudinal decline in anti-Id levels. OBJECTIVE AND DESIGN: We investigated anti-Id levels in longitudinal samples obtained from T1D patients (n = 41) (clinical diagnosis - 12 months), and latent autoimmune diabetes in adults (LADA) patients (n = 32) who received alum-formulated human recombinant GAD65 (baseline - 12 months). We also determined anti-Id levels in a small cohort of Type 2 diabetes patients during their development of autoimmune T cell responses. RESULTS: At clinical onset T1D patients presented no or low anti-Id levels. However, 22/41 T1D patients showed ≥50% increase in GAD65Ab-specific anti-Id levels during follow-up; peaking at 3 (n = 1), 6 (n = 10), 9 (n = 10), or 12 (n = 1) months. Increasing anti-Id levels marked patients who experienced a temporary increase in C-peptide levels. Anti-Id levels correlated significantly with glycated hemoglobin and C-peptide levels at 6 and 9 months (P values ranged from <0.001 to <0.05). In LADA patients receiving placebo, anti-Id levels declined in seven of nine patients, whereas four of five patients receiving 20 µg alum-formulated human recombinant GAD65 showed increasing anti-Id levels. Changes in anti-Id and C-peptide levels closely correlated (P < 0.0001). The significant decline in anti-Id levels (P = 0.03) in T2D patients developing T cell autoimmune responses supports our hypothesis that declining anti-Id levels are associated with developing islet autoimmunity. CONCLUSIONS: The close association between GAD65Ab-specific anti-Id levels and ß-cell function may provide a novel marker for the progression of autoimmune diabetes.

Altered natural killer (NK) cell frequency and phenotype in latent autoimmune diabetes in adults (LADA) prior to insulin deficiency.

Approximately 10% of the patients diagnosed with type 2 diabetes (T2D) have detectable serum levels of glutamic acid decarboxylase 65 autoantibodies (GADA). These patients usually progress to insulin dependency within a few years, and are classified as being latent autoimmune diabetes in adults (LADA). A decrease in the frequency of peripheral blood natural killer (NK) cells has been reported recently in recent-onset T1D and in high-risk individuals prior to the clinical onset. As NK cells in LADA patients have been investigated scarcely, the aim of this study was to use multicolour flow cytometry to define possible deficiencies or abnormalities in the frequency or activation state of NK cells in LADA patients prior to insulin dependency. All patients were GADA-positive and metabolically compensated, but none were insulin-dependent at the time blood samples were taken. LADA patients exhibited a significant decrease in NK cell frequency in peripheral blood compared to healthy individuals (P=0.0018), as reported previously for recent-onset T1D patients. Interestingly, NKG2D expression was increased significantly (P<0.0001), whereas killer cell immunoglobulin-like receptor (KIR)3DL1 expression was decreased (P<0.0001) within the NK cell population. These observations highlight a defect in both frequency and activation status of NK cells in LADA patients and suggest that this immunological alteration may contribute to the development of autoimmune diabetes by affecting peripheral tolerance. Indeed, recent evidence has demonstrated a regulatory function for NK cells in autoimmunity. Moreover, the decrease in NK cell number concords with observations obtained in recent-onset T1D, implying that similar immunological dysfunctions may contribute to the progression of both LADA and T1D.

Temporal trends of HLA genotype frequencies of type 1 diabetes patients in Sweden from 1986 to 2005 suggest altered risk.

The aim of this study was to compare the frequency of human leukocyte antigen (HLA) genotypes in 1-18-year-old patients with type 1 diabetes newly diagnosed in 1986-1987 (n = 430), 1996-2000 (n = 342) and in 2003-2005 (n = 171). We tested the hypothesis that the HLA DQ genotype distribution changes over time. Swedish type 1 diabetes patients and controls were typed for HLA using polymerase chain reaction amplification and allele specific probes for DQ A1* and B1* alleles. The most common type 1 diabetes HLA DQA1*-B1*genotype 0501-0201/0301-0302 was 36% (153/430) in 1986-1987 and 37% (127/342) in 1996-2000, but decreased to 19% (33/171) in 2003-2005 (P \ 0.0001). The 0501-0201/0501-0201 genotype increased from 1% in 1986-1987 to 7% in 1996-2000 (P = 0.0047) and to 5% in 2003-2005 (P > 0.05). This study in 1-18-year-old Swedish type 1 diabetes patients supports the notion that there is a temporal change in HLA risk.

Regulatory T cell-associated activity in photopheresis-induced immune tolerance in recent onset type 1 diabetes children.

Extracorporeal photochemotherapy (ECP) has demonstrated immunological effects. The proposed cytotoxic lymphocyte antigen 4 (CTLA-4) involvement, together with forkhead box P3 (FoxP3) and transforming growth factor (TGF)-beta are associated with regulatory T cell activity. The aim of the study was to evaluate the regulatory T cell-associated effect of ECP in recent onset type 1 diabetic (T1D) children. Children (n = 20) with T1D received photopheresis 8-methoxypsoralen + ECP or placebo + shampheresis. Peripheral blood mononuclear cells (PBMC) collected pretreatment (day 1) and post-treatment (day 90) were stimulated with phytohaemagglutinin (PHA) and T1D-associated glutamic acid decarboxylase 65 (GAD(65)) peptide a.a. 247-279. CTLA-4, sCTLA-4, FoxP3 and TGF-beta mRNA transcription was quantified. Photopheresis-treated individuals' relative mRNA expression was generally maintained during the course of the study. Placebo individuals increased in spontaneous CTLA-4 mRNA (P < 0.05) but decreased in expression after stimulation with GAD(65)-peptide (P < 0.05) and PHA (P < 0.05). Spontaneous TGF-beta (P < 0.05) increased whereas PHA- (P < 0.01) and GAD(65)-peptide (P < 0.01)-induced TGF-beta expression decreased in the placebo group, whereas it was maintained in the treated group. Without intervention, expression of CTLA-4 and TGF-beta, stimulated with PHA and GAD(65) peptide, decreased with time, with a parallel reduction of GAD(65)-peptide and PHA-stimulated TGF-beta expression. These parameters were counteracted by ECP. In conclusion, our results indicate that ECP maintains regulatory T cell-associated activity in recent-onset T1D.

Evidence for de novo expression of thymic insulin by peripheral bone marrow-derived cells.

Thymic expression of insulin has been suggested to play a major role in negative selection of autoreactive T cells and tolerance induction against pancreatic beta cells. Furthermore, the expression of insulin in peripheral antigen-presenting cells (APC) has been clearly demonstrated but whether thymic negative selection and tolerance induction also depends on peripheral influx of self-antigens (Ag) remains to be conclusively demonstrated. In this study, we wanted to test whether peripheral influx of insulin expressing cells might contribute to negative selection. In order to address this question, we used mice deficient in the Ins1 and Ins2 genes. Embryonic thymi either deficient in both insulin genes or expressing Ins2 were dissected and transplanted under the kidney capsule of athymic nude mice recipients. After indicated time points, grafted thymi were removed and analysed for insulin re-expression and for the emergence of autoreactive T cells. The analysis revealed a re-expression of Ins2 in grafted insulin deficient thymi suggesting that self-Ag expression in the thymus is not only intrinsically regulated but peripheral influx of APC capable of expressing insulin might contribute to thymic selection and tolerance induction.

Cord blood islet autoantibodies and seasonal association with the type 1 diabetes high-risk genotype.

OBJECTIVE: Human leukocyte antigen DQ (HLA-DQ) genetic factors and islet autoantibodies are strongly associated with type 1 diabetes (T1D) and are currently used to predict T1D. This study examined whether islet autoantibodies in the cord blood of newborns to nondiabetic mothers were associated with the (T1D) high-risk genotype HLA-DQ2/8, gestational infections or both. STUDY DESIGN: Cord blood samples were taken from 33 683 newborns and used for HLA typing and analyses of islet autoantibodies. Parents completed questionnaires when the child was 2 months of age. RESULT: The prevalence of newborn islet autoantibodies consistently varied with season over 4 years (P<0.0001); lowest in first quarter (1.2%) and highest in third (2.4%). Cord blood islet autoantibodies were associated with HLA-DQ2/8 in the second (OR, 2.30; P=0.02), third (OR, 2.12; P=0.008) and fourth quarters (OR, 2.49; P=0.007), but not in the first (OR, 1.13). Reported gastroenteritis was additionally associated with islet autoantibodies in the third quarter (OR, 1.80, P=0.04). CONCLUSION: An association between HLA and islet autoimmunity may depend on environmental exposure during pregnancy. Follow-up of mothers and children will determine risk of T1D.

Inflammation at birth and the insulin-like growth factor system in very preterm infants.

BACKGROUND: Foetal inflammation is associated with an increased risk of brain damage in preterm infants whereas IGF-I is essential for cerebral development and exhibits anti-apoptotic properties. AIM: To assess levels of IGF-I and IGF binding proteins at very preterm birth and to evaluate their relationship with foetal pro-inflammation and cerebral damage. METHODS: Levels of IGF-I, IGF binding protein 3 (IGFBP-3), high- (hp) and low-phosphorylated (lp) IGFBP-1 in cord blood and neonatal blood at 72 h after delivery were analysed in relation to levels of cytokines and cerebral damage as detected by ultrasound in 74 inborn infants [mean gestational age (GA) 27.1 weeks]. Evaluation was performed separately according to birth weight for GA. RESULTS: In cord blood of infants appropriate for gestational age (AGA) higher levels of IL-6 and IL-8 were associated with lower IGF-I (r =-0.38, p = 0.008 and r =-0.36, p = 0.014). Higher levels of IL-6, IL-8 and TNF-alpha were associated with both higher levels of lpIGFBP-1 (r = 0.54, p < 0.001, r = 0.50, p < 0.001 and r = 0.13, p = 0.012, respectively) and hpIGFBP-1 (r = 0.55, p < 0.001, r = 0.45, p = 0.002 and r = 0.32, p = 0.026, respectively). Infants with intraventricular haemorrhage grade III (n = 5) had higher levels of lp/hpIGFBP-1 in cord blood (p = 0.001 and 0.002, respectively). CONCLUSION: Pro-inflammation at birth is associated with changes in the IGF-system. This may be of importance for development of brain damage in preterm infants.

GAD65 autoantibody epitopes in adult patients with latent autoimmune diabetes following GAD65 vaccination.

AIMS: Subcutaneous injection of recombinant human GAD65 (rhGAD65) in patients with latent autoimmune diabetes in adults (LADA) correlates with an increase in C-peptide levels. In this study we analysed the effect of rhGAD65 administration on the GAD65-specific autoimmune response. METHODS: Longitudinal serum samples obtained from LADA patients (n = 47) who received 4, 20, 100 or 500 microg alum-formulated rhGAD65 or placebo by subcutaneous injection twice (4 weeks apart) were analysed for their epitope recognition using GAD65-specific recombinant Fab and GAD65/67 fusion proteins. RESULTS: Overall, minor changes in the epitope pattern were observed using either approach. Only in the 500-microg dosage group was an increase in GAD65Ab level associated with a significant increase in the binding to a conformational epitope located at the middle part of GAD65. CONCLUSIONS: Our data suggest that the apparent beneficial effects of 20 microg alum-formulated recombinant human GAD65 is not explained by changes in the GAD65Ab epitope pattern.

Evidence for immunological priming and increased frequency of CD4+ CD25+ cord blood T cells in children born to mothers with type 1 diabetes.

Maternal transmission of islet autoantibodies to children born to mothers with type 1 diabetes (T1D) has been shown to protect from autoantibodies and diabetes development later in life. However, the factors conferring disease protection are poorly understood. The aim of this study was to evaluate comparatively proinflammatory cytokines, autoantibodies and lymphocyte subsets in cord blood (CB) of children born to mothers with either T1D (n = 13), gestational diabetes (GDM) (n = 32) or healthy mothers (n = 81) in relation to transplacental passage of autoantibodies. The results are consistent with early priming of the fetal immune system only in children born to mothers with T1D. Levels of interleukin (IL)-1beta (P = 0.022), tumour necrosis factor (TNF)-alpha (P = 0.002) and IL-8 (P = 0.0012), as well as the frequency of CD4(+) CD25(+) T cells (P < 0.01) were significantly increased, and the increased levels correlated positively with anti-GAD65 autoantibody (GADA) levels. Moreover, CD4(+) CD25(+) T cells of children born to T1D mothers exhibited a more pronounced memory phenotype with increased CCR4 expression and down-regulation of CD62L. These data suggest that early activation of the fetal immune system as a consequence of maternal autoimmunity and transplacental passage of GADA may influence the generation and expansion of fetal regulatory T cells. This might induce an early antigen-specific immunological tolerance that could protect against T1D later in life.

The -374 T/A polymorphism in the gene encoding RAGE is associated with diabetic nephropathy and retinopathy in type 1 diabetic patients.

AIMS/HYPOTHESIS: The receptor for AGE (RAGE) is considered to be mainly an intracellular signal-transducer or pro-inflammatory peptide of possible importance for inflammation and autoimmune diseases. Our aim was to study whether the -374 T/A polymorphism in the gene encoding RAGE (AGER) is associated with diabetes type and presence of diabetic complications. METHODS: The AGER -374 T/A polymorphism was genotyped in 867 type 1 diabetic patients, 2,467 type 2 diabetic patients and 205 non-diabetic control subjects of Scandinavian origin. RESULTS: AGER polymorphism was related to different HLA-DQB1 genotypes and the presence of diabetic complications. Type 1 diabetic patients had a higher frequency of the AGER -374 A/A or T/A genotypes than type 2 diabetic patients (51.1 vs 44.9%, p=0.002) and control subjects (51.1 vs 47.6%, p=0.0006). The RAGE -374 T/A polymorphism was associated with HLA-DQB1 genotypes; patients with HLA risk genotypes had a higher frequency of the A/A or T/A genotypes than patients with other HLA-DQB1 genotypes (60.3 vs 40.3%, p<0.000001). In type 1 diabetic patients, the frequency of the A/A or T/A genotypes was higher in patients with diabetic nephropathy than without (61.1 vs 46.8%, p=0.006) and with sight-threatening retinopathy than without (56.1 vs 47.6%, p=0.03). In type 2 diabetic patients with HbA(1c) values below the median, the T/T genotype was more frequent in patients with diabetic nephropathy than without (54.3 vs 38.2%, p=0.02). CONCLUSIONS/INTERPRETATION: Our results show an association between the AGER -374 T/A polymorphism and type 1 diabetes. This association was HLA-DQB1-dependent. The polymorphism was associated with diabetic nephropathy in both type 1 and type 2 diabetes, in an HbA(1c)-dependent manner in the latter group, and also with sight-threatening retinopathy in type 1 diabetic patients.

Reduction of tissue transglutaminase autoantibody levels by gluten-free diet is associated with changes in subsets of peripheral blood lymphocytes in children with newly diagnosed coeliac disease.

Tissue transglutaminase (tTG) autoantibodies decline after gluten-free diet in patients with coeliac disease. We tested the hypothesis that gluten-free diet-induced change in tTG autoantibody levels affects subsets of peripheral blood lymphocytes. Peripheral blood was obtained from 20 children with biopsy-proven active coeliac disease. Gluten-free diet was initiated and the children examined again after three and six months. tTG autoantibodies were measured in radioligand binding assays and lymphocyte subsets by flow cytometry. IgA-tTG levels at diagnosis, 2204 U/ml (median, range 113-24990), were reduced over six months to 76 U/ml (median, range 1-1261) (P < 0.001). At six months, 12/20 (60%) children had reduced their IgA-tTG levels to < 100 U/ml and these children showed a decrease in B cells (mean change -3.8%, P = 0.014), CD4+ T cells (mean -4.32%, P = 0.011) and CD4+ T cells expressing CD25high (mean change -0.62%, P = 0.036). In contrast, the CD4+CD25(high)CCR4+ T cell population increased during the same period (mean change 11.5%, P = 0.0036). The decline in IgA-tTG levels correlated to the decrease in B cells (r = 0.56, P = 0.01), CD4+ T cells (r = 0.66, P = 0.004) as well as CD4+CD25high T cells (r = 0.59, P = 0.01). A negative correlation was found between the decline in IgA-tTG and CD4+CD25high T cells expressing CD45RO (r = -0.49, P = 0.03) and CCR4 (r = -0.54, P = 0.01). This is the first observational study on the effect of gluten-free diet on concurrent changes of tTG autoantibodies and specific peripheral blood lymphocyte subsets. Our data suggest that flow cytometry may be a useful complement to tTG autoantibodies when studying the effects of gluten-free diet in children with coeliac disease.

Characterization of a naturally occurring mutation (L107I) in the HNF1 alpha (MODY3) gene.

AIMS/HYPOTHESIS: Maturity onset diabetes of the young type 3 (MODY3) is a monogenic form of diabetes mellitus caused by mutations in the gene encoding for hepatocyte nuclear factor 1 alpha, HNF1 alpha. In this study we have examined the in vivo and in vitro effects of a mutation (L107I) outside the DNA binding and dimerization domains in the N terminal part of the HNF1 alpha gene. METHODS: Beta-cell function of the affected family members was assessed by an oral glucose tolerance test. Functional tests were carried out to explain the role of the mutation in vitro by transcriptional activity assay, Western blotting, DNA-binding assays and subcellular localization experiments. RESULTS: Affected family members showed an 86% decreased insulin response to glucose when compared to age-matched healthy control subjects. In vitro the mutation showed a 79% decrease in transcriptional activity as compared to wild type HNF1 alpha in HeLa cells lacking HNF1 alpha. The transcriptional activity was not suppressed when the mutant was co-expressed with wild type HNF1 alpha suggesting that the decreased activity was not mediated by a dominant negative mechanism. The L107I/HNF1alpha protein showed normal nuclear targeting but impaired binding to an HNF1 alpha consensus sequence. CONCLUSION/INTERPRETATION: Our results suggest that the L107I substitution represents a MODY3 mutation which impairs beta-cell function by a loss-of-function mechanism.