Epitope analysis of GAD65 autoantibodies in adult-onset type 1 diabetes and latent autoimmune diabetes in adults with thyroid autoimmunity

Bivalent GAD autoantibody ELISA improves clinical utility and risk prediction for adult autoimmune diabetes

AIM/INTRODUCTION

To investigate the differences in the clinical significance and glutamic acid decarboxylase autoantibody (GADA) affinity between RIA (RIA-GADA) and ELISA (ELISA-GADA) in patients with type 1 diabetes.

METHODS

A total of 415 patients with type 1 diabetes were enrolled, including 199 acute-onset type 1 diabetes, 168 slowly progressive type 1 diabetes (SPIDDM), and 48 fulminant type 1 diabetes. GADA affinity was measured by a competitive binding experiment using unlabeled recombinant human GAD65 protein, and the diagnostic performance of both assays and the relationship between GADA affinity and the decline of fasting C-peptide (F-CPR) were examined.

RESULTS

While the ELISA-GADA displayed a higher sensitivity than the RIA method in diagnosing type 1 diabetes in acute-onset patients, about 40% of SPIDDM patients with low-titer RIA-GADA were determined as negative by the ELISA method. Patients with type 1 diabetes with RIA-GADA alone had an older age of onset, less diabetic ketoacidosis, a higher BMI, and a higher F-CPR compared with patients positive for both RIA-GADA and ELISA-GADA. Additionally, 36% of RIA-GADA-positive patients had low-affinity GADA (<10¹⁰  L/mol), which was significantly higher than in the ELISA-GADA-positive patients (4%, P < 0.0001). Furthermore, over a 3 year monitoring period, F-CPR levels decreased in ELISA-GADA-positive SPIDDM, whereas it was maintained in patients with RIA-GADA alone, regardless of GADA affinity.

CONCLUSIONS

These results suggest that bivalent ELISA for GADA is superior to the RIA method in diagnosing type 1 diabetes. Moreover, the diagnostic superiority of the ELISA-GADA made possible the concurrent identification of SPIDDM patients at high-risk of early progression, and allowed for more accurate clinical diagnosis and management.

Diagnostic Dilemmas and Current Treatment Approaches in Latent Onset Autoimmune Diabetes in Adults: A Concise Review

Latent Onset Autoimmune Diabetes in Adults (LADA) is an autoimmune disorder between T1DM and T2DM and is often misdiagnosed as T2DM due to its late-onset. The disease is characterized by β-cell failure and slow progression to insulin dependence. Early diagnosis is significant in limiting disease progression. C-peptide levels and autoantibodies against β-cells are the most critical diagnostic biomarkers in LADA. The review aims to provide an overview of the biomarkers used to diagnose LADA, and the following treatment approaches. We have summarized LADA's pathophysiology and the autoantibodies involved in the condition, diagnostic approaches, and challenges. There are clear shortcomings concerning the feasibility of autoantibody testing. Finally, we have explored the treatment strategies involved in the management of LADA. In conclusion, the usual management includes treatment with metformin and the addition of low doses of insulin. Newer oral hypoglycaemic agents, such as GLP-1RA and DPP-4 inhibitors, have been brought into use. Since the disease is not entirely understood at the research level and in clinical practice, we hope to encourage further research in this field to assess its prevalence. Large randomized controlled trials are required to compare the efficacy of different available treatment options.

Diabetic ketoacidosis as first presentation of latent autoimmune diabetes in adults in a patient with hashitoxicosis as first presentation of Hashimoto's thyroiditis: a case report

Background

Latent autoimmune diabetes in adults is an infrequent form of autoimmune diabetes mellitus, while Hashimoto’s thyroiditis, the most common thyroid disease in adults, rarely manifests as thyrotoxicosis. The concurrent initial presentation of these two autoimmune disorders is extremely rare.

Case presentation

A 29-year-old male of Albanian descent presented after being hospitalized owing to diabetic ketoacidosis. The diagnosis of type 1 diabetes mellitus was placed, and intensified insulin therapy was initiated. Medical history was not of significance except a 5 kg weight loss within 2 months. The patient presented with recurrent episodes of hypoglycemia, and the doses of preprandial and basal insulin were reduced. The differential diagnosis included type 1 diabetes mellitus “honeymoon” period or another type of diabetes mellitus. His serological tests only revealed positive autoantibodies against glutamic acid decarboxylase 65 and C-peptide. The diagnosis leaned toward latent autoimmune diabetes in adults, and the therapeutic approach involved cessation of preprandial insulin therapy, regulation, and subsequent discontinuation of basal insulin and introduction of metformin. Two years later, basal insulin was reintroduced along with a glucagon-like peptide-receptor agonist and metformin. Further physical examination during the initial visit disclosed upper limb tremor, lid lag, excessive sweating, increased sensitivity to heat, and tachycardia. Laboratory tests were indicative of hashitoxicosis (suppressed level of thyroid-stimulating hormone, high levels of total and free thyroid hormones, positive anti-thyroglobulin and anti-thyroid peroxidase, and negative anti-thyroid-stimulating hormone receptor). Thyroid-stimulating hormone level was spontaneously restored, but an increase was observed during follow-up. Levothyroxine was administrated for 2 years until the patient had normal thyroid function.

Conclusions

The prevalence of thyroid autoantibodies in patients with latent autoimmune diabetes in adults ranges from 20% to 30%. This correlation can be attributed to genetic involvement as well as disorders of immune tolerance to autoantigens. Hence, this report gives prominence to the holistic approach and consideration of comorbidities in patients with diabetes mellitus.

GAD65 Antibody Epitopes and Genetic Background in Latent Autoimmune Diabetes in Youth (LADY)

Epitope-specific GAD65Abs and HLA-DR-DQ gene assays help improve the value of risk stratification in autoimmune diabetes mellitus and protect islet function. Identification and early intervention are important for latent autoimmune diabetes in youth (LADY). The aims of this study were to investigate 1) the frequencies of the epitope-specific GAD65Abs and HLA-DR-DQ genes in LADY and 2) the association between HLA-DR-DQ genes and epitope-specific GAD65Abs. Higher frequencies of GAD65-CAb and multiepitope GAD65Abs were observed in young type 1 diabetes, LADY, and old type 1 diabetes subjects than those in latent autoimmune diabetes in adult (LADA) patients. The frequencies of the specific susceptible HLA haplotype DR3, total susceptible HLA haplotypes, and high-risk genotypes were higher in type 1 diabetes and LADY patients than those in LADA patients. In contrast, type 1 diabetes and LADY patients had lower frequencies of low/no genetic risk genotypes (DRX/X) than those of LADA patients. Logistic regression analysis suggested that the susceptible HLA haplotypes were risk factors for glutamic acid decarboxylase antibody (GADA) multiepitope positivity in autoimmune diabetes mellitus. LADY may be more severe than LADA, and LADY seemed to be a transitional type of type 1 diabetes and LADA. GADA epitope and HLA-DR-DQ gene assays are important for risk stratification in autoimmune diabetes mellitus and protection of islet function.

Latent Autoimmune Diabetes in Adults (LADA): From Immunopathogenesis to Immunotherapy

Latent autoimmune diabetes in adults (LADA) is a type of diabetes characterized by slow autoimmune damage of pancreatic β cells without insulin treatment in the early clinical stage. There are differences between LADA and classical type 1 diabetes (T1D) and type 2 diabetes (T2D) in genetic background, autoimmune response, rate of islet function decline, clinical metabolic characteristics, and so on. The disease progression and drug response of patients with LADA are closely related to the level of islet autoimmunity, thus exploring the pathogenesis of LADA is of great significance for its prevention and treatment. Previous studies reported that adaptive immunity and innate immunity play a critical role in the etiology of LADA. Recent studies have shown that the intestinal microbiota which impacts host immunity hugely, participates in the pathogenesis of LADA. In addition, the progression of autoimmune pancreatic β cell destruction in LADA is slower than in classical T1D, providing a wider window of opportunities for intervention. Therefore, therapies including antidiabetic drugs with immune-regulation effects and immunomodulators could contribute to promising interventions for LADA. We also shed light on potential interventions targeting the gut microbiota and gut-associated immunity, which may be envisaged to halt or delay the process of autoimmunity in LADA.

rs3806265 and rs4612666 of the NLRP3 Gene Are Associated With the Titer of Glutamic Acid Decarboxylase Antibody in Type 1 Diabetes

BACKGROUND AND AIMS

The NLRP3 gene is reportedly associated with several autoimmune diseases. However, in the Chinese Han population, whether NLRP3 polymorphisms are associated with type 1 diabetes (T1D) is unclear. Therefore, this study examined the associations of rs3806265 and rs4612666 of the NLRP3 gene with T1D susceptibility and the clinical characteristics of Chinese Han T1D patients.

METHODS

In total, 510 classic T1D patients and 531 healthy controls from the Chinese Han population were recruited for a case-control study. rs3806265 and rs4612666 of the NLRP3 gene were genotyped by MassARRAY. Logistic regression analysis and the chi-square test were used to compare the distributions of the alleles and genotypes of rs3806265 and rs4612666. The relationships between rs3806265 and rs4612666 and the clinical characteristics of T1D patients were analyzed by Kruskal-Wallis one-way ANOVA. Student's t test was used to analyze normally distributed data. Bonferroni correction was used for multiple comparisons.

RESULTS

1) rs3806265 was associated with glutamic acid decarboxylase antibody (GADA) titers (P = 0.02), and patients with the CC genotype had higher GADA titers than patients with the TT genotype. 2) rs4612666 was also associated with GADA titers (P=0.041). Compared with patients with the CC genotype, patients with the TT genotype had higher GADA titers. 3) rs3806265 and rs4612666 of the NLRP3 gene were not significantly associated with T1D susceptibility under different genetic models.

CONCLUSION

rs3806265 and rs4612666 of the NLRP3 gene were significantly associated with GADA titers in Chinese Han T1D patients.

The polymorphism of the CARD8 inflammasome-related gene is associated with glutamic-acid-decarboxylase-antibody positivity in patients with type 1 diabetes mellitus

Background

This study sought to examine the correlation between 2 single-nucleotide polymorphisms (SNPs; rs10403848 and rs2043211) in the caspase recruitment domain-containing protein 8 (CARD8) gene and the risks and clinical features of patients with type 1 diabetes mellitus (T1DM) in the Han Chinese population.

Methods

A case-control study involving the Han Chinese population was designed, and individuals diagnosed with classical T1DM and healthy controls were enrolled in this study. MassARRAY genotyped the SNPs of rs10403848 and rs2043211. Logistic regression and chi-square analyses were conducted to compare the allele distributions and genotypes of the T1DM and healthy control participants. A Kruskal-Wallis 1-way analysis of variance was used to perform the genotype-phenotype analysis for the T1DM patients.

Results

In total, 510 participants with classical T1DM and 531 sex-matched healthy control participants participated in this study. The CARD8 SNP of rs2043211 was significantly associated with the rate of glutamic-acid-decarboxylase-antibody (GADA) positivity among T1DM patients (P=0.021). However, no significant differences in the distributions of alleles or the genotypes of rs10403848 and rs2043211 were observed between the case and control groups, and these 2 SNPs were not associated with T1DM under various inheritance models.

Conclusions

The rs10403848 and rs2043211 polymorphisms of CARD8 were not associated with susceptibility to T1DM. However, rs2043211 was found to be correlated with GADA positivity in participants with T1DM.

Islet Autoantibodies in the Patients with Sjogren's Syndrome and Thyroid Disease and Risk of Progression to Latent Autoimmune Diabetes in Adults: A Case Series

The glutamic acid decarboxylase 65 antibody (GAD65-Ab) is an autoimmune marker in some diseases such as diabetes or autoimmune disorders of the central nervous system such as stiff-man syndrome. It can appear with other pancreatic autoantibodies, such as insulin autoantibodies (IAA), presenting as early signs of pancreatic islet β-cells impairing, and play roles in the pathogenesis of type1 diabetes (T1D) and latent autoimmune diabetes in adults (LADA). Positive GAD65-Ab is rarely observed in insulin-dependent diabetic patients with other acquired autoimmune diseases, such as Sjogren's syndrome (SS). Besides, LADA revealed by islet autoantibodies such as GAD65-Ab can also be complicated with Hashimoto's thyroiditis (HT), another autoimmune thyroid disease. To date, whether GAD65-Ab positive in patients with autoimmune diseases predicts the onset or progression to T1D or LADA remains unknown. Herein, two unique cases of middle-aged Chinese Han women free from diabetes for three years are described despite their blood tests persistently testing positive for GAD65-Ab or IAA. Both patients suffered from HT and SS. Follow-up OGTTs (oral glucose tolerance test) for three years revealed that the patients had a well-controlled glycemic level and normal pancreatic function. However, one of the patients had a temporary increase of postprandial glucose after a short-term loss of diet control. The presence of auto-immune antibodies in these patients had little impact on glucose tolerance or insulin secretion in 3 years. The study postulate that both the primary immune injury caused by serum GAD65-Ab positive, an autoimmune marker, and increased body weight contribute to the progression of LADA.

Clinical characteristics of GAD 65-associated autoimmune encephalitis

OBJECTIVES

To examine the clinical characteristics of autoimmune encephalitis associated with the glutamate decarboxylase 65 (GAD 65) antibody.

MATERIALS AND METHODS

Medical records of all patients that diagnosed with GAD 65 antibody-associated encephalitis were retrospectively analyzed. Data regarding demographics and symptoms, neurological signs, laboratory and imaging results, treatment and prognosis were collected.

RESULTS

We collected a total of seven patients, mainly young or middle-aged women with a subacute or chronic course. The main clinical symptoms mainly included chronic epilepsy, cerebellar ataxia, stiff-person syndrome, and limbic encephalitis. Three of seven (43%) patients had high CSF (cerebrospinal fluid) protein levels. Oligoclonal IgG bands (including IgG 1) and 24 hours intrathecal synthesis of IgG were detected in CSF and serum in six patients, five patients (83%) reported increased distribution of oligoclonal IgG bands (including IgG 1) and 24 hours intrathecal synthesis of IgG in serum and CSF. And six of seven patients (86%) had abnormal thyroid function or were positive for thyroid antibodies. By electroencephalogram examination, sharp or slow waves in the temporal region were often observed for six of seven patients (86%). Abnormal imaging signals (six of seven patients, 86%) of the temporal lobe and hippocampus were detected by brain magnetic resonance imaging, and decreased metabolism of the temporal lobe was detected by positron emission tomography/computed tomography (six of six patients, 100%). These patients were mainly treated with corticosteroid and gamma globulin. The clinical symptoms of the patients were alleviated.

CONCLUSIONS

The course of GAD 65 antibody-associated encephalitis is longer than other autoimmune encephalitides. The clinical symptoms of GAD 65 autoimmune encephalitis mainly manifested as chronic epilepsy, cerebellar ataxia, stiff-person syndrome, and limbic encephalitis, and combined with or without thyroid autoimmune diseases, type 1 diabetes, and thymoma. A comprehensive understanding of the disease is a way to prevent misdiagnosis and delayed treatment.

Clinical and genetic characteristics of people with type 1 diabetes who have discrepancies in titers of anti-glutamic acid decarboxylase antibody measured by radioimmunoassay and enzyme-linked immunosorbent assay

AIMS/INTRODUCTION

The aim of the present study was to compare the clinical and genetic characteristics between people with type 1 diabetes who were positive and negative for autoantibodies against glutamic acid decarboxylase (GADA) measured by enzyme-linked immunosorbent assay (ELISA) with low-titer GADA measured by radioimmunoassay.

MATERIALS AND METHODS

Among Japanese people with type 1 diabetes in whom GADA were measured by both ELISA and radioimmunoassay, those who had low titers of GADA measured by radioimmunoassay (1.5-10 U/mL), regardless of positivity for GADA measured by ELISA, were studied. There were 65 participants with acute-onset type 1 diabetes and 30 participants with slowly progressive insulin-dependent diabetes mellitus. Clinical characteristics and human leukocyte antigen types were compared in ELISA-positive (≥5 U/mL) and ELISA-negative participants. Endogenous insulin secretion was evaluated by C-peptide index.

RESULTS

Among participants with slowly progressive insulin-dependent diabetes mellitus, postprandial C-peptide index was significantly higher in ELISA-negative participants than in ELISA-positive participants (r = 0.619, P = 0.002). Among 52 participants whose human leukocyte antigen typing was carried out, all of the participants with slowly progressive insulin-dependent diabetes mellitus who had DRB1*09:01 were positive by GADA-ELISA (P = 0.021). In acute-onset type 1 diabetes participants, there were no significant differences for the C-peptide index and human leukocyte antigen genotypes.

CONCLUSIONS

The difference in the positivity for GADA-ELISA might reflect cytotoxicity toward pancreatic β-cells and preservation of endogenous insulin secretion in people with slowly progressive insulin-dependent diabetes mellitus. We also suggest that the difference in the GADA-ELISA-specific epitope depends on the human leukocyte antigen genotype.

Polymorphisms of the NLRC4 Gene are Associated with the Onset Age, Positive Rate of GADA and 2-h Postprandial C-Peptide in Patients with Type 1 Diabetes

PURPOSE

The purpose of this study was to clarify the association between the NLRC4 gene and the susceptibility and clinical characteristics of type 1 diabetes (T1D) in a Chinese Han population.

PATIENTS AND METHODS

A case-control study was performed in a Chinese Han population including 510 classical T1D patients and 531 healthy controls. rs212704 and rs385076 of the NLRC4 gene were genotyped by MassARRAY. The frequency distributions of alleles and genotypes of polymorphisms in the NLRC4 gene were compared by logistic regression and the chi-square test. The relationships between the polymorphisms of the NLRC4 gene and various clinical characteristics were analyzed by Kruskal-Wallis one-way ANOVA. The statistical power was calculated by Quanto software.

RESULTS

1) rs385076 of the NLRC4 gene was significantly correlated with the onset age of T1D patients and the positive rate of GADA. The relationship between rs212704 and 2-h postprandial C-peptide was statistically significant. 2) There was no significant difference in the frequency distributions of the genotypes and alleles of rs212704 and rs385076 between T1D patients and controls. 3) rs212704 and rs385076 were not correlated with T1D susceptibility under different genetic models.

CONCLUSION

rs212704 was associated with 2-h postprandial C-peptide, while rs385076 of the NLRC4 gene was associated with the onset age and positive rate of GADA in patients with T1D.

Past, present and future of latent autoimmune diabetes in adults

Latent autoimmune diabetes in adults (LADA) is the most common form of autoimmune diabetes diagnosed in adults. Similar to type 1 diabetes, the prevalence of LADA is impacted by ethnicity and geography. LADA is characterized by β cell loss due to autoimmunity and insulin resistance and has highly heterogeneous clinical features, autoimmunity, and genetics in a glutamic acid decarboxylase antibody (GADA) titre-dependent manner, suggesting LADA is part of a continuum spectrum between type 1 and type 2 diabetes. Although LADA is the most frequent form of autoimmune diabetes diagnosed in adults, clinical trials involving LADA are scarce. Here we review the recent advancements in LADA epidemiology, clinical features, pathogenesis, and interventions. We also highlight the environmental factors that are thought to play an important role in addition to genetics in the pathogenesis of LADA. In the future, high-throughput molecular profiles might shed light on the nature of LADA among the wide spectrum of diabetes and offer new opportunities to identify novel LADA-specific biomarkers.

Clinical manifestation and islet β-cell function of a subtype of latent autoimmune diabetes in adults (LADA): positive for T cell responses in phenotypic type 2 diabetes

AIMS

To investigate the possibility of identifying a subtype of latent autoimmune diabetes in adults (LADA), T-LADA (T cell responses-positive and autoantibody-negative) from patients with phenotypic type 2 diabetes (T2D) by enzyme-linked immunospot (ELISPOT).

METHODS

Eighty-two patients with phenotypic T2D were studied. Autoantibodies against glutamic acid decarboxylase (GAD), insulinoma-associated protein-2 and zinc transporter 8 were measured by radioligand assay. Thirty-nine Ab⁺ and 43 Ab^- patients with phenotypic T2D were enrolled for T cell assay of responses to GAD65 and C-peptide antigen by ELISPOT.

RESULTS

(1) Eleven of 43 Ab^- participants with phenotypic T2D were demonstrated interferon (IFN)-γ secreting T cells by ELISPOT, while 13 of 39 Ab⁺ patients with phenotypic T2D were positive for T cells responses to islet antigens. (2) The onset ages of T cell⁺ people with phenotypic T2D were younger than that of T cell^- individuals (42.7 ± 9.3 vs. 48.2 ± 10.2 years, P = 0.025). Moreover, T cell⁺ patients with T2D displayed a significantly lower fasting C-peptide (FCP) compared with T cell^- participants [0.28 (0.02-0.84) vs. 0.42 (0.05-1.26) nmol/L, P = 0.013]. (3) Ab^-T⁺ group had a significantly lower FCP compared with Ab^-T^- group [0.31 (0.13-0.84) vs. 0.51 (0.07-1.26) nmol/L, P = 0.023].

CONCLUSIONS

By measuring T cell responses to islet antigens in patients with phenotypic T2D, we identified a specific subtype of LADA who may be associated with worse basal β-cell function than classic T2D (Ab^-T^-).

Slowly Progressive Type 1 Diabetes Mellitus: Current Knowledge And Future Perspectives

Slowly progressive type 1 insulin-dependent diabetes mellitus (SPIDDM), sometimes referred to as latent autoimmune diabetes in adults (LADA), is a heterogeneous disease that is often confused with type 1 and type 2 diabetes. As a result, there were few diagnostic criteria for this disorder until 2012, when the Japan Diabetes Society established criteria that could be used in clinical practice. A primary question is whether pathologic markers for type 1 or type 2 diabetes are present in the pancreas of patients with SPIDDM, because the phenotype of SPIDDM is similar to both type 1 and type 2 diabetes. Recent studies clarified pathologic findings in the pancreas of patients with SPIDDM, which included T-cell-mediated insulitis, a marker of type 1 diabetes; pseudoatrophic islets (islets specifically devoid of beta cells), another hallmark of type 1 diabetes; and a lack of amylin (ie, islet amyloid polypeptide) deposition to the islet cells, a pathologic marker of type 2 diabetes. In terms of preventing the loss of beta-cell function in patients with SPIDDM, several studies have shown that some drugs, including dipeptidyl peptidase-4 inhibitors, are effective. There is an increased need for early diagnosis of SPIDDM to preserve beta-cell function. This review presents updated findings on the pathogenesis and immunologic findings of the affected pancreas, diagnostic markers, risk factors for progression of beta-cell dysfunction, epidemiology, clinical features, diagnostic strategies, prevention strategies, and clinical options for patients with SPIDDM.

Autoimmune Diseases in Children and Adults With Type 1 Diabetes From the T1D Exchange Clinic Registry

BACKGROUND AND AIMS

Type 1 diabetes (T1D) is associated with other autoimmune diseases (AIDs), but the prevalence and associated predictive factors for these comorbidities of T1D across all age groups have not been fully characterized.

MATERIALS AND METHODS

Data obtained from 25 759 participants with T1D enrolled in the T1D Exchange Registry were used to analyze the types and frequency of AIDs as well as their relationships to gender, age, and race/ethnicity. Diagnoses of autoimmune diseases, represented as ordinal categories (0, 1, 2, 3, or more AIDs) were obtained from medical records of Exchange Registry participants.

RESULTS

Among the 25 759 T1D Exchange participants, 50% were female, 82% non-Hispanic white, mean age was 23.0 ± 16.9 years and mean duration of diabetes was 11 years. Of these participants, 6876 (27%) were diagnosed with at least one AID. Frequency of two or more AIDs increased from 4.3% in participants aged younger than 13 years to 10.4% in those aged 50 years or older. The most common AIDs were thyroid (6097, 24%), gastrointestinal (1530, 6%), and collagen vascular diseases (432, 2%). Addison's disease was rare (75, 0.3%). The prevalence of one or more AIDs was increased in females and non-Hispanic whites and with older age.

CONCLUSIONS

In the T1D Exchange Clinic Registry, a diagnosis of one or more AIDs in addition to T1D is common, particularly in women, non-Hispanic whites, and older individuals. Results of this study have implications for both primary care and endocrine practice and will allow clinicians to better anticipate and manage the additional AIDs that develop in patients with T1D.

Persistence of glutamic acid decarboxylase antibody (GADA) is associated with clinical characteristics of latent autoimmune diabetes in adults: a prospective study with 3-year follow-up

BACKGROUND

Latent autoimmune diabetes in adults (LADA) is a form of autoimmune diabetes with heterogeneous features. This study aimed to investigate the persistent status of glutamic acid decarboxylase antibody (GADA) in patients with LADA and its association with clinical characteristics.

METHODS

This 3-year follow-up study enrolled 107 LADA and 40 type 2 diabetes mellitus (T2DM) patients from October 2005 to December 2013. GADA titer, epitopes, and clinical characteristics (including fasting C-peptide and HbA1c ) in LADA patients were assayed annually. The human leukocyte antigen DQ (HLA-DQ) genotypes were also analysed. The relationship between the persistence of GADA and the clinical characteristics was investigated in LADA patients.

RESULTS

After 3-year follow-up, 36.5% (39/107) LADA patients remained GADA positive (persistently positive group), 19.6% (21/107) patients fluctuated positively and negatively (fluctuating group), and 43.9% (47/107) patients became GADA negative, among which 61.7% (29/47) seroconversions occurred within 6 months of follow-up (transiently positive group). The GADA persistently positive group possessed higher titer of GADA than transiently positive group and fluctuant group (all p = 0.000), higher reactivities to middle and C-terminal regions of GAD65 than those in transiently positive group (p = 0.001 and p = 0.000, respectively), and lower baseline fasting C-peptide level than T2DM patients and transiently positive group [415(31-1862) vs 620(220-1658) pmol/L, p = 0.014; and 415(31-1862) vs 705(64-1541) pmol/L, p = 0.017, respectively]. The GADA transiently positive group retained a higher HbA1c level when compared with T2DM patients (p = 0.023). In addition, the three LADA groups shared similar frequencies of HLA-DQ susceptible haplotypes that were higher as compared with T2DM. The GADA persistently positive group had a higher annual declining rate in fasting C-peptide than T2DM patients [-14%(-174-33%) vs -1%(-27-28%), p = 0.007].

CONCLUSION

The LADA patients with GADA transient positivity account for a large proportion, whose clinical characteristics and HLA-DQ haplotypes are different from those of T2DM. The patients with high titer GADA and reactivities to GADA65 middle and C-terminal regions showed a persistent GADA positivity, in which a worse baseline and accelerated decline of β-cell function need early intervention in the practice. Copyright © 2016 John Wiley & Sons, Ltd.

The association of cytotoxic T-lymphocyte antigen-4 + 49A/G and CT60 polymorphisms with type 1 diabetes and latent autoimmune diabetes in Chinese adults

OBJECTIVE

The aim of this study was to investigate the association of cytotoxic T-lymphocyte antigen-4 (CTLA-4) + 49A/G and CT60 polymorphisms with latent autoimmune diabetes in adults (LADA) and the genetic differences between LADA, type 1 diabetes (T1DM), and type 2 diabetes (T2DM) in a Chinese population.

SUBJECTS

A total of 231 LADA, 402 T1DM, and 330 T2DM patients as well as 482 nondiabetic controls were recruited in the study.

METHODS

CTLA-4 + 49A/G and CT60 polymorphisms were analyzed by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). The level of glutamic acid decarboxylase antibodies (GADAs) was detected by a radioligand binding assay.

RESULTS

The CTLA-4 + 49A/G risk genotype GG was most frequent in T1DM patients (45.3%), followed by LADA patients (44.2%) and T2DM patients (38.8%). Significantly higher frequencies of the risk genotype GG were observed in the T1DM (OR = 1.532, 95% CI 1.168-2.010, P = 0.002) and LADA patients (OR = 1.464, 95% CI 1.063-2.017, P = 0.019). The frequencies of the CTLA-4 CT60 risk genotype GG were 65.2, 61.9, 58.5, and 56.4% in the T1DM, LADA, T2DM, and control groups, respectively. The CTLA-4 CT60 GG risk genotypes were only associated with T1DM (OR = 1.445, 95% CI 1.1-1.898, P = 0.008). Compared with controls, patients having a high titer of GADA (GADA ≥ 180 IU/ml) had higher frequencies of the GG risk genotype of CTLA-4 + 49 A/G (49.4% vs. 35.1% OR = 1.807, 95% CI 1.125-2.903, P = 0.014), but there was no difference between patients having a low titer of GADA and controls.

CONCLUSION

The CTLA-4 + 49 A/G polymorphism confers genetic susceptibility to LADA and T1DM, while the CTLA-4 CT60 polymorphism is only associated with T1DM in Chinese population. The CTLA-4 + 49 A/G genotype distribution in LADA is associated with the GADA level.

The association of PTPN22 rs2476601 polymorphism and CTLA-4 rs231775 polymorphism with LADA risks: a systematic review and meta-analysis

Although the polymorphisms of PTPN22 and the variants of CTLA-4 have been reported to be the susceptibility genes, which increased risk of latent autoimmune diabetes in adults (LADA), the results remained inconclusive. The aim of this meta-analysis was to evaluate the association between the polymorphisms of two genes and LADA. We performed a systematic review by identifying relevant studies and applied meta-analysis to pool gene effects. Data from ten studies published between 2001 and 2013 were pooled for two polymorphisms: rs2476601 in the PTPN22 gene and rs231775 in the CTLA-4 gene. Data extraction and assessments for risk of bias were independently performed by two reviewers. Fixed-effect model and random-effect model were used to pool the odds ratios; meanwhile, heterogeneity test, publication bias and sensitive analysis were explored. The minor T allele at rs2476601 and the minor G at rs231775 carried estimated relative risks (odds ratio) of 1.52 (95 % CI 1.29-1.79) and 1.39 (95 % CI 1.11-1.74), respectively. These alleles contributed to an absolute lowering of the risk of all LADA by 4.88 and 14.93 % when individuals do not carry these alleles. The estimated lambdas were 0.49 and 0.63, suggesting a codominant model of effects was most likely for two genes. In summary, our systematic review has demonstrated that PTPN22 rs2476601 and CTLA-4 rs231775 are potential risk factors for LADA. An updated meta-analysis is required when more studies are published to increase the power of these polymorphisms and LADA.

A novel mutation in autoimmune regulator gene causes autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy

BACKGROUND

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED) is a rare autosomal recessive disease due to mutations in the autoimmune regulator (AIRE) gene, which encodes a transcription factor that induces the expression of peripheral tissue-specific antigens in medullary thymic epithelial cells.

AIM

The purpose of this study was to identify the underlying genetic cause in a Chinese family diagnosed with APECED.

METHOD

Peripheral blood samples were collected from family members. All exons of the AIRE gene and adjacent exon-intron sequences were amplified by PCR and subsequently sequenced. The functional consequence of the mutations was analyzed by cell transfection and in vitro assays.

RESULTS

A novel c.483_484insC mutation in exon 4 was identified, which resulted in a frame shift predicted to generate a truncated protein containing the first 163 AIRE amino acids followed by 52 aberrant amino acids. Confocal immunofluorescence microscopy of COS-7 cells transfected with wild-type and mutant AIRE constructs showed that wild-type AIRE protein was localized mainly in the nucleus, while mutant AIRE was localized mainly in the cytoplasm. A luciferase reporter assay showed that the identified mutation dramatically inhibited the transactivation activity of AIRE in vitro.

CONCLUSION

We identified a novel AIRE mutation which alters the intracellular location and transcription activity of AIRE, and has implications in the pathogenesis of APECED.

Latent autoimmune diabetes in adults in Asians: similarities and differences between East and West

Latent autoimmune diabetes in adults (LADA) is a form of autoimmune diabetes with features of both type 1 and type 2 diabetes and in the middle of the diabetes spectrum. Scientists clash on the question of whether this type of diabetes is a unique diabetes subtype. Multicenter studies have been performed in different countries, including the Korea National Diabetes Program (KNDP) collaboratory group, the Ehime study in Japan, the Not Insulin-Requiring Autoimmune Diabetes (NIRAD) study in Italy, the Nord-Trøndelag Health (HUNT) study in Norway, the UK Prospective Diabetes Study (UKPDS) in the UK, the Action LADA study in Europe and the LADA China study in China. These studies found universal immunogenetic effects associated with LADA, but with some ethnic differences. Herein we summarize those multicenter studies and compare the ethnic similarities and differences between East and West from epidemiological, clinical, immune, and genetic viewpoints.

Autoantibodies to CCL3 are of low sensitivity and specificity for the diagnosis of type 1 diabetes

Type 1 diabetes (T1D) is a T cell-dependent tissue-specific autoimmune disease, characterized by the selective destruction of the β cells of the pancreatic islets of Langerhans. Recently, contradictory findings have been reported about the relationship of autoantibodies to CC chemokine 3 (CCL3) and T1D, which need to be confirmed by more investigations in larger cohorts. The aim of our research was to investigate whether autoantibodies to CCL3 are useful markers for T1D in a large cohort of Chinese patients. We analyzed autoantibodies to CCL3, glutamic acid decarboxylase(GADA), insulinoma-associated protein-2 (IA-2A), and zinc transporter-8 (ZnT8A) by a radioimmunoprecipitation assay in 290 T1D subjects, 200 subjects with type 2 diabetes (T2D), 210 subjects with other diseases, and 178 healthy control subjects. Results showed that the frequencies of autoantibodies to CCL3 in subjects with T1D, T2D, and healthy control subjects were similar [3.10% (9/290), 2.50% (5/200), and 0.56% (1/178), respectively, P = 0.189]. Autoantibodies to CCL3 were not significantly different between T1D patients with or without GADA, IA-2A, or ZnT8A antibodies (2.7% vs. 3.9%, P = 0.725). In contrast, patients with systemic lupus erythematosus and rheumatoid arthritis showed higher positivity for autoantibodies to CCL3 than healthy control subjects [15.6% (5/32) and 12.5% (8/64) vs. 0.56% (1/178), all P = 0.000], and higher titer of autoantibodies to CCL3 than T1D patients (median 0.9633 and 0.4095 vs. 0.0873, P = 0.012 and P = 0.034, respectively). We conclude that autoantibodies to CCL3 are of low sensitivity and specificity for T1D and cannot be used in the diagnosis of T1D.

Long-lasting remission of type 1 diabetes following treatment with topiramate for generalized seizures

We report a case of unusually long-lasting remission of type 1 diabetes (T1D). The patient, a Caucasian man, at the age of 43 years developed a ketotic diabetes, classified as type 1 based on clinical presentation and positivity for islet autoantibodies. Shortly after diabetes onset, oral topiramate was added to preexisting valproic acid for generalized seizures and maintained thereafter. Initial intensive insulin treatment was rapidly reduced to low doses (3 Units/day) maintained for a long time and then discontinued at month 55; fasting glucose and glycosylated hemoglobin were basically normalized at 58 months. An oral glucose tolerance test performed at month 53 showed an impaired fasting glucose (6.0 mmol/l) and a value slightly above the threshold for the diagnosis of diabetes at 2 h (11.2 mmol/l). We hypothesize that this unusually prolonged preservation of β-cell function might be ascribed to the concomitant therapy with topiramate, an antiepileptic agent with demonstrated efficacy as antidiabetic in type 2 diabetes (T2D). Topiramate should be further investigated as candidate agent for the preservation of β-cell function also in T1D.

No signs of progressive beta cell damage during 20 years of prospective follow-up of autoantibody-negative diabetes

Both type 1 and type 2 diabetes are considered to be associated with different degrees of progressive beta cell damage. However, few long-term studies have been made. Our aim was to study the clinical course of 20 years of diabetes disease, including diabetes progression, comorbidity, and mortality in a prospectively studied cohort of consecutively diagnosed diabetic patients. Among all 233 patients diagnosed with diabetes during 1985-1987 in Malmö, Sweden, 50 of 118 surviving patients were followed-up after 20 years. The age at diagnose was 42.3 ± 23.1 and 57.5 ± 13.6 years for antibody-positive and antibody-negative patients, respectively. HbA1c and plasma lipids were analyzed with regard to metabolic control. Islet antibody-negative patients at diagnosis had highly preserved C-peptide levels after 20 years in contrast to antibody-positive patients (antibody negative: C-peptide 0 years 0.78 ± 0.47 and 20 years 0.70 ± 0.46 (nmol/l), P = 0.51 and antibody positive: C-peptide 0 years 0.33 ± 0.35 and 20 years 0.10 ± 0.18; P < 0.001. Islet antibodies but not age, BMI, or C-peptide at diagnosis were predictors of C-peptide levels at 20 years when analyzed by logistic regression (P < 0.05). HbA1c did not differ between the groups after 20 years. The 20-year mortality was higher among antibody-negative patients, dependent on the higher age at diagnosis in this group (number of deaths: antibody positive: 18 of 56 vs. antibody negative: 109 of 188, P < 0.001). Of the deceased, 79% had died from diseases or complications that may be associated with diabetes. We found no progressive beta cell damage in autoantibody-negative diabetes at a 20-year follow-up of the clinical course of diabetes.

GAD65 autoantibodies and its role as biomarker of Type 1 diabetes and Latent Autoimmune Diabetes in Adults (LADA)

One of the hallmarks of autoimmune diabetes is the presence of adaptive responses directed to neuroendocrine proteins. One of these proteins is glutamic acid decarboxylase (GAD). While GAD is widely distributed in neuroendocrine tissues, its specific significance in diabetes has paralleled the advances in understanding humoral and cellular immunity in Type 1 diabetes (T1D) and in a subset of Type 2 diabetes (T2D), going from the seminal discoveries of islet autoantibodies to the development and standardization of bioassays as diagnostic tools, to studies on the structure of GAD and its antigenic determinants. GAD65 autoantibodies can accurately predict T1D development in combination with other surrogate humoral biomarkers and they are considered the most sensitive and specific biomarker which identifies a subset of clinically diagnosed T2D termed Latent Autoimmune Diabetes in Adults (LADA). We and others provided evidence indicating that GAD65 autoantibody detection should be part of the diagnostic assessment for clinically diagnosed T2DM mainly because it predicts the rate of progression to insulin requirement in patients affected by LADA. More recently GAD has been used as a "tolerogenic vaccine" to preserve beta cell function in autoimmune diabetes. While the results of Phase III clinical trials did not substantiate the earlier promise of Phase I and II trials, there are still many unanswered questions and approaches that need to be investigated in the applications of GAD in the therapy of T1D and LADA.