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

A new perspective of frozen shoulder pathology; the interplay between the brain and the immune system

Frozen shoulder (FS), also known as adhesive capsulitis of the shoulder (FS), is a fibrotic inflammatory process of unknown etiology whose main symptoms are pain, stiffness and the loss of joint mobility. These symptoms may be associated with pathologies such as diabetes, Dupuytren's syndrome and the prevalence of today's sedentary lifestyle. This literature review provides an overview of the epidemiology and pathogenesis of this pathology, as well as the mechanisms of lowgrade chronic inflammation and infection, insulin resistance, and omics-science associated with it. We also propose a new hypothesis related to the possibility that the GABAergic system could play a decisive role in the development of frozen shoulder and that therefore diabetes type 1, endocrinological autoimmune disorders and frozen shoulder are connected by the same pathophysiological mechanisms. If that is true, the combined presence of psycho-emotional stress factors and pathogenic immune challenges could be the main causes of frozen shoulder syndrome. Finally, we propose a series of possible intervention strategies based on a multifactorial etiological and mechanistic concept.

Novel STAT3 variant causing infantile-onset autoimmune disease

Signal transducer and activator of transcription 3 (STAT3) is a member of the STAT protein family implicated in the development of infantile-onset multisystem autoimmune disease. STAT3-related autoimmune disease is characterized by multiorgan autoimmunity, lymphoproliferative disease, and recurrent infections. The presentation is variable, with some patients also developing neonatal diabetes mellitus and interstitial lung disease. Gain-of-function variants in the Src homology 2 domain, leading to autophosphorylation and activation of STAT3, have been previously reported in patients with disease. Here, we report a patient with a novel missense variant, p.Glu616Ala, in STAT3 presenting with infantile-onset multisystem autoimmune disease.

Autoimmune Encephalitis With Autoimmune Diabetes: A Case of Horror Autotoxicus

Diagnosing autoimmune encephalitis relies on clinical, radiological, and serological studies. Several autoantibodies have been implicated and recognized, with dozens of potential targets identified in the past 20 years. Despite that progress, some patients with encephalitis present a diagnostic dilemma with a seronegative status. The presence of other autoimmune diseases in a patient with encephalitis should provide a clue to the autoimmune nature of a developing neurological syndrome (cognitive, psychiatric, behavioral, and catatonia). In this report, we describe the case of a young man with type 1 diabetes mellitus who was diagnosed with seronegative autoimmune encephalitis after presenting with catatonia. We describe the lengthy clinical course, the various therapeutic trials, and his clinical outcome and response to B-cell depleting agent. This study also discusses the potential pathophysiologic pathways, providing a rationale for the diagnostic workup and therapeutic options for autoimmune encephalopathy in this case presentation.

Stiff person syndrome spectrum disorders; more than meets the eye

Stiff person syndrome spectrum disorders (SPSD) are a group of rare neuroimmunological disorders that often include painful spasms and rigidity. However, patients have highly heterogeneous signs and symptoms which may reflect different mechanistic disease processes. Understanding subsets of patients based on clinical phenotype may be important for prognosis and guiding treatment. The goal of this review is to provide updates on SPSD and its expanding clinical spectrum, prognostic markers, and treatment considerations. Further, we describe the current understanding in immunopathogenesis and highlight gaps in our knowledge appropriate for future research directions. Examples of revised diagnostic criteria for SPSD based on phenotype are also presented.

Alternating exosomes and their mimetics as an emergent strategy for targeted cancer therapy

Exosomes, a subtype of the class of extracellular vesicles and nano-sized particles, have a specific membrane structure that makes them an alternative proposition to combat with cancer through slight modification. As constituents of all most all the primary body fluids, exosomes establish the status of intercellular communication. Exosomes have specific proteins/mRNAs and miRNAs which serve as biomarkers, imparting a prognostic tool in clinical and disease pathologies. They have efficient intrinsic targeting potential and efficacy. Engineered exosomes are employed to deliver therapeutic cargos to the targeted tumor cell or the recipient. Exosomes from cancer cells bring about changes in fibroblast via TGFβ/Smad pathway, augmenting the tumor growth. These extracellular vesicles are multidimensional in terms of the functions that they perform. We herein discuss the uptake and biogenesis of exosomes, their role in various facets of cancer studies, cell-to-cell communication and modification for therapeutic and diagnostic use.

The relationship between GAD65 autoantibody and the risk of T1DM onset

Objectives

Type 1 diabetes mellitus (T1DM) is a well-known autoimmune disease, characterized by β-cell destruction in pancreas islet cells, which results insulin deficiency and subsequent hyperglycemic sequelae. While there is screening for type 2 DM that leads to better glycemic control and outcome, the majority of T1DM patients are diagnosed when much of the pancreatic cells and their function are disturbed. The aim of this article is to present an overview of the effective factors in the positivity of Glutamic acid decarboxylase antibody )GADA( and identifying the high-risk individuals for T1DM.

Methods

We searched English literature available at National Library of Medicine via PubMed, and Google Scholar through December 2020. Finally, 79 papers have been included in the study. Studies were summarized based on the number of positive autoantibodies and onset of T1DM over time and GADA correlation with different variables.

Conclusions

GADA is an easy marker to measure that can be detected many months prior to the clinical presentation and remains positive even after early childhood.

Preventing type 1 diabetes development and preserving beta-cell function

PURPOSE OF REVIEW

Type 1 diabetes (T1D) is the most common chronic disease of childhood presenting a significant burden, both in terms of day-to-day medical management and lifelong care. Studies aligned with diverse strategies to prevent or modify the course of T1D are reviewed.

RECENT FINDINGS

The diagnosis of T1D precedes the classic clinical presentation when insulin dependence develops. With an increased understanding of the pathophysiology of the autoimmune process leading to T1D, treatment strategies to prevent the development of autoimmunity and/or modify the immune response have been trialed in persons at risk for developing the disease. Interventions prior to insulin dependence or very early after clinical diagnosis show some promise both in preventing disease onset and prolonging beta-cell insulin production.

SUMMARY

Significant progress has been made in the treatment of T1D. However, suboptimal glycemic control remains a challenge impacting overall health and quality of life for patients with this chronic disease. Although physicians and basic sciences investigators continue to pursue the prevention of the autoimmune process, the advent of disease-modifying agents is a promising strategy. Further studies are needed to ensure that insulin preservation can be achieved longer term.

Peptide Antibody Reactivity to Homologous Regions in Glutamate Decarboxylase Isoforms and Coxsackievirus B4 P2C

Two isoforms of the glutamate decarboxylase (GAD) enzyme exist, GAD65 and GAD67, which are associated with type 1 diabetes (T1D) and stiff-person syndrome (SPS), respectively. Interestingly, it has been reported that T1D patients seldom develop SPS, whereas patients with SPS occasionally develop T1D. In addition, coxsackievirus B4 (CVB4) has previously been proposed to be involved in the onset of T1D through molecular mimicry. On this basis, we aimed to examine antibody cross-reactivity between a specific region of GAD65 and GAD67, which has high sequence homology to the nonstructural P2C protein of CVB4 to determine potential correlations at antibody level. Monoclonal peptide antibodies generated in mice specific for a region with high similarity in all three proteins were screened for reactivity along with human sera in immunoassays. In total, six antibodies were generated. Two of the antibodies reacted to both GAD isoforms. However, none of the antibodies were cross-reactive to CVB, suggesting that antibody cross-reactivity between GAD65 and CVB, and GAD67 and CVB may not contribute to the onset of T1D and SPS, respectively.

Similarities between bacterial GAD and human GAD65: Implications in gut mediated autoimmune type 1 diabetes

A variety of islet autoantibodies (AAbs) can predict and possibly dictate eventual type 1 diabetes (T1D) diagnosis. Upwards of 75% of those with T1D are positive for AAbs against glutamic acid decarboxylase (GAD65 or GAD), a producer of gamma-aminobutyric acid (GABA) in human pancreatic beta cells. Interestingly, bacterial populations within the human gut also express GAD and produce GABA. Evidence suggests that dysbiosis of the microbiome may correlate with T1D pathogenesis and physiology. Therefore, autoimmune linkages between the gut microbiome and islets susceptible to autoimmune attack need to be further elucidated. Utilizing in silico analyses, we show that 25 GAD sequences from human gut bacterial sources show sequence and motif similarities to human beta cell GAD65. Our motif analyses determined that most gut GAD sequences contain the pyroxical dependent decarboxylase (PDD) domain of human GAD65, which is important for its enzymatic activity. Additionally, we showed overlap with known human GAD65 T cell receptor epitopes, which may implicate the immune destruction of beta cells. Thus, we propose a physiological hypothesis in which changes in the gut microbiome in those with T1D result in a release of bacterial GAD, thus causing miseducation of the host immune system. Due to the notable similarities we found between human and bacterial GAD, these deputized immune cells may then target human beta cells leading to the development of T1D.

The early detection of type 1 diabetes mellitus and latent autoimmune diabetes in adults (LADA) through rapid test reverse-flow immunochromatography for glutamic acid decarboxylase 65 kDa (GAD65)

Background

Diabetes mellitus (DM) is a chronic and costly disease that has become a primary concern worldwide. Type 1 diabetes mellitus is categorized as an autoimmune disease, which results in islet cell apoptosis and insulin-dependent. GAD₆₅ is known as a potential marker of impaired pancreatic β cell function that appears in the initial phase of type 1 DM and latent autoimmune diabetes in adults (LADA). This study aimed to develop a novel rapid test of anti-GAD₆₅ autoantibodies in human serum samples.

Methods

We have developed a rapid test for anti-GAD65 autoantibodies in this assay based on the reverse-flow immunochromatography method. Human recombinant-protein antigen for GAD₆₅ was attached as the control line over the nitrocellulose membrane. On the other side, the goat anti-mouse immunoglobulin G (IgG) was coated on the same membrane as a control line. The positive result for GAD₆₅ was confirmed by a colloidal gold signal on the strip. Our novel assay analyzed 276 healthy subjects and 51 type 1 diabetes individuals serum samples from several ethnicities in Indonesia for this study.

Results

Among the 276 healthy samples, 225 samples were identified as positive for anti-GAD₆₅ autoantibodies, while 51 samples were negative. Interestingly, the positive results for anti-GAD₆₅ autoantibodies were linear to the decreasing of high-density lipoprotein (HDL) levels and inversely associated with triglyceride levels. A significant correlation with age was observed in all groups. The sensitivity and specificity test proved that this kit has higher accuracy (AUC value = 0.960).

Conclusion

The significant advantages of our rapid test for anti-GAD₆₅ autoantibodies provide higher sensitivity, specificity, and stability compared to previous commercial kits. Therefore, it could be proposed as the future clinical diagnostic kit for patient management of type 1 DM.

An atypical presentation of type 1 diabetes

Type 1 and type 2 diabetes have been described historically as occurring in distinct patient populations; however, atypical demographics are becoming more frequent as the prevalence of diabetes increases, crossing boundaries of ages. Some of these cases can be challenging to diagnose clinically as the patient symptomatology and progression can differ from the standard features of type 1 and 2 diabetes. Our case is an example of a patient whose type 1 diabetes presented atypically with characteristics often associated with type 2 diabetes. Patient presentations such as this are uncommon, with our patient having presented with the “textbook” characteristics of type 2 diabetes. When first diagnosed with diabetes mellitus type 2, the patient was 60 years old, had a BMI around 30 and experienced a gradual onset of symptoms over the course of several months. At the age of 64, the patient tested positive for GAD65 autoantibodies following a year of declining glycemic control and was re-evaluated and classified as a type 1 diabetes patient. Subsequent insulin injections resolved his diabetes-related complications which included polyuria, weakness and weight loss and improved his glycemic control. This case provides an example of an unusual clinical presentation of type 1 diabetes and serves to raise awareness for atypical presentations of diabetes to improve accurate classifications at earlier stages.

Hyperosmolar Hyperglycaemic State and Diabetic Ketoacidosis in Nivolumab-Induced Insulin-Dependent Diabetes Mellitus

Nivolumab is a monoclonal antibody directed against programmed cell death-1 receptor. It has an increasing application in the treatment of various advanced metastatic cancers. The incidence of autoimmune side effects associated with such agents is expected to increase. New-onset autoimmune diabetes mellitus associated with immune checkpoint inhibitor treatment is rare, occurring in less than 1% of patients. Nivolumab-induced diabetes often presents as diabetic ketoacidosis, which could be life-threatening if not recognized and treated promptly. We present the case of a patient who developed severe diabetic ketoacidosis concomitant with hyperosmolar hyperglycaemic state (HHS) after receiving nivolumab for metastatic testicular lymphoma. Pre-nivolumab blood glucose levels were normal, apart from transient hyperglycaemia related to steroids as part of the chemotherapy protocol. The diagnosis was confirmed with extremely low C-peptide in the clinic.

LEARNING POINTS

Checkpoint inhibitor-associated diabetes can present abruptly with life-threatening complications.Most patients require multiple daily injections of insulin upon discharge.Cessation of checkpoint inhibitor therapy does not revert diabetes.

Glutamic acid decarboxylase 65-positive autoimmune encephalitis presenting with gelastic seizure, responsive to steroid: A case report

BACKGROUND

Anti-glutamic acid decarboxylase (GAD) antibody is known to cause several autoimmune-related situations. The most known relationship is that it may cause type I diabetes. In addition, it was also reported to result in several neurologic syndromes including stiff person syndrome, cerebellar ataxia, and autoimmune encephalitis. Decades ago, isolated epilepsy associated with anti-GAD antibody was first reported. Recently, the association between temporal lobe epilepsy and anti-GAD antibody has been discussed. Currently, with improvements in examination technique, many more autoimmune-related disorders can be diagnosed and treated easier than in the past.

CASE SUMMARY

A 44-year-old female Asian with a history of end-stage renal disease (without diabetes mellitus) under hemodialysis presented with diffuse abdominal pain. The initial diagnosis was peritonitis complicated with sepsis and paralytic ileus. Her peritonitis was treated and she recovered well, but seizure attack was noticed during hospitalization. The clinical impression was gelastic seizure with the presentation of frequent smiling, head turned to the right side, and eyes staring without focus; the duration was about 5–10 s. Temporal lobe epilepsy was recorded through electroencephalogram, and she was later diagnosed with anti-GAD65 antibody positive autoimmune encephalitis. Her seizure was treated initially with several anticonvulsants but with poor response. However, she showed excellent response to intravenous methylprednisolone pulse therapy. Her consciousness returned to normal, and no more seizures were recorded after 5 d of intravenous methylprednisolone treatment.

CONCLUSION

In any case presenting with new-onset epilepsy, in addition to performing routine brain imaging to exclude structural lesion and cerebrospinal fluid studies to exclude common etiologies of infection and inflammation, checking the autoimmune profile has to be considered. In the practice of modern medicine, autoimmune-related disorders are relatively treatable and should not be missed.

Oxidative Stress in Autoimmune Diseases: An Under Dealt Malice

Oxidative stress is the off-balance of antioxidants and free radicals. All kinds of diseases and disorders give rise to oxidative damage including autoimmune diseases. An autoimmune disorder is a pathological condition characterized by the breakdown of self-tolerance of the immune system in the body. Immunological processes against tissues and organs lead to enhanced oxidative stress and, in turn, misbalance of oxidative stress aggravates the pathobiology of the disease. Highly reactive nature of free radicals, for example hydroxyl and superoxide ions, alters DNA, protein, and lipids in the body which augment the pathologic processes of diseases. The damaged biomolecules are responsible for systemic complications and secondary disease co-morbidities. In this review, we discuss the role of oxidative stress in some incapacitating autoimmune diseases like Rheumatoid arthritis, Systemic Lupus Erythematosus, Type 1 Diabetes, and Multiple Sclerosis. Oxidative stress plays a central and course defining role in these diseases and it has become a necessity to study the pathological mechanism involved in oxidative stress to better understand and offer treatment holistically. Presently there are no clinically available parameters for measurement and treatment of pathological oxidative stress, therefore it requires intensive research. Probably, in the future, the discovery of easily detectable markers of oxidative stress can aid in the diagnosis, prognosis, and treatment of progressively destructive autoimmune diseases.

Prevention strategies for type 1 diabetes: a story of promising efforts and unmet expectations

A number of studies have investigated primary and secondary prevention strategies for type 1 diabetes (T1D), since early interventions might improve long-term outcomes through the amelioration of immune processes and the preservation of beta-cell mass. Primary prevention trials focus on genetically at-risk individuals prior to the appearance of autoimmunity, whereas secondary prevention trials aim to halt the progression of complete beta-cell destruction in subjects with established islet autoimmunity (IA). Different approaches have been tested so far, focusing on both pharmaceutical (insulin and monoclonal antibodies) and non-pharmaceutical (vitamin D, omega-3 fatty acids, probiotics, and nicotinamide) interventions, as well as on environmental factors that are believed to trigger autoimmunity in T1D (cow's milk, gluten, and bovine insulin). Albeit certain strategies have displayed efficacy in reducing IA development rates, most efforts have been unsuccessful in preventing the onset of the disease in high-risk individuals. Moreover, significant heterogeneity in study designs, included populations, and explored outcomes renders the interpretation of study results challenging. The aim of this narrative review is to present and critically evaluate primary and secondary prevention strategies for T1D, seeking to fill existing knowledge gaps and providing insight into future directions.

Immunomodulatory potential of anti-idiotypic antibodies for the treatment of autoimmune diseases

The immune system is a complex network of specialized cells and organs that recognises and reacts against foreign pathogens while remaining unresponsive to host tissues. This ability to self-tolerate is known as immunological tolerance. Autoimmune disease occurs when the immune system fails to differentiate between self and non-self antigens and releases autoantibodies to attack our own cells. Anti-idiotypic (anti-ID) antibodies are important in maintaining a balanced idiotypic regulatory network by neutralising and inhibiting the secretion of autoantibodies. Recently, anti-ID antibodies have been advanced as an alternative form of immunotherapy as they can specifically target autoantibodies, cause less toxicity and side effects, and could provide long-lasting immunity. This review article discusses the immunomodulatory potential of anti-ID antibodies for the treatment of autoimmune diseases.

The immune system protects the body against infections and diseases, such as by producing antibodies. Usually, these antibodies only attack pathogens, leaving healthy cells unharmed. However, autoimmune disease may develop when the immune system mistakenly recognises part of the body as foreign and produces antibodies to attack them. Antibodies that attack our own cells are called autoantibodies. Anti-idiotypic antibodies could be utilized to stop autoantibodies from attacking self cells with minimal side effects and long-lasting immunity. This review discusses anti-idiotypic antibodies usage as an alternative form of immunotherapy to inhibit autoantibodies in autoimmune disease.

RORγt Inhibitor-SR1001 Halts Retinal Inflammation, Capillary Degeneration, and the Progression of Diabetic Retinopathy

Diabetic retinopathy is a diabetes-mediated retinal microvascular disease that is the leading cause of blindness in the working-age population worldwide. Interleukin (IL)-17A is an inflammatory cytokine that has been previously shown to play a pivotal role in the promotion and progression of diabetic retinopathy. Retinoic acid-related orphan receptor gammaT (RORγt) is a ligand-dependent transcription factor that mediates IL-17A production. However, the role of RORγt in diabetes-mediated retinal inflammation and capillary degeneration, as well as its potential therapeutic attributes for diabetic retinopathy has not yet been determined. In the current study, we examined retinal inflammation and vascular pathology in streptozotocin-induced diabetic mice. We found RORγt expressing cells in the retinal vasculature of diabetic mice. Further, diabetes-mediated retinal inflammation, oxidative stress, and retinal endothelial cell death were all significantly lower in RORγt-/- mice. Finally, when a RORγt small molecule inhibitor (SR1001) was subcutaneously injected into diabetic mice, retinal inflammation and capillary degeneration were ameliorated. These findings establish a pathologic role for RORγt in the onset of diabetic retinopathy and identify a potentially novel therapeutic for this blinding disease.

Geographic location determines beta-cell autoimmunity among adult Ghanaians: Findings from the RODAM study

Introduction

Beta‐cell autoantibodies are established markers of autoimmunity, which we compared between Ghanaian adults with or without diabetes, living in rural and urban Ghana and in three European cities.

Methods

In the multicenter cross‐sectional Research on Obesity and Diabetes among African Migrants (RODAM) study (N = 5898), we quantified autoantibodies against glutamic acid decarboxylase (GAD65Ab) by radioligand binding assay (RBA) and established cut‐offs for positivity by displacement analysis. In a subsample, we performed RBA for zinc transporter‐8 autoantibodies (ZnT8Ab). Associations of environmental, sociodemographic, and clinical factors with GAD65Ab were calculated.

Results

In this study population (age: 46.1 ± 11.9 years; female: 62%; Ghana‐rural: 1111; Ghana‐urban: 1455; Europe: 3332), 9.2% had diabetes with adult‐onset. GAD65Ab concentrations were the highest in Ghana‐rural (32.4; 10.8‐71.3 U/mL), followed by Ghana‐urban (26.0; 12.3‐49.1 U/mL) and Europe (11.9; 3.0‐22.8 U/mL) with no differences between European cities. These distributions were similar for ZnT8Ab. Current fever, history of fever, and higher concentrations of liver enzymes marginally explained site‐specific GAD65Ab concentrations. GAD65Ab positivity was as frequent in diabetes as in nondiabetes (5.4% vs 6.1%; P = .25). This was also true for ZnT8Ab positivity.

Conclusion

Geographic location determines the occurrence of GAD65Ab and ZnT8Ab more than the diabetes status. Beta‐cell autoimmunity may not be feasible to differentiate diabetes subgroups in this population.

Uncommon Presentations of Diabetes: Zebras in the Herd

The majority of patients with diabetes are diagnosed as having either type 1 or type 2 diabetes. However, when encountered in clinical practice, some patients may not match the classic diagnostic criteria or expected clinical presentation for either type of the disease. Latent autoimmune, ketosis-prone, and monogenic diabetes are nonclassical forms of diabetes that are often misdiagnosed as either type 1 or type 2 diabetes. Recognizing the distinguishing clinical characteristics and understanding the diagnostic criteria for each will lead to appropriate treatment, facilitate personalized medicine, and improve patient outcomes.

Human Leukocyte Antigen (HLA) and Islet Autoantibodies Are Tools to Characterize Type 1 Diabetes in Arab Countries: Emphasis on Kuwait

The incidence rate of type 1 diabetes in Kuwait had been increasing exponentially and has doubled in children ≤ 14 years old within almost two decades. Therefore, there is a dire need for a careful systematic familial cohort study. Several immunogenetic factors affect the pathogenesis of the disease. The human leukocyte antigen (HLA) accounts for the major genetic susceptibility to the disease. The triggering agents initiate disease onset by type 1 destruction of pancreatic β-cells. Both HLA and anti-islet antibodies can be used to characterize, predict susceptibility to the disease, innovate, or delay the β-cell destruction. Evidence from prospective longitudinal studies suggested that the underlying disease process represents a continuum that begins before the symptoms are clinically evident. Autoimmunity of the functional pancreatic β-cells results in symptomatic type 1 diabetes and lifelong insulin dependence. The autoantibodies against glutamic acid decarboxylase (GADA), insulinoma antigen-2 (IA-2A), insulin (IAA), and zinc transporter-8 (ZnT-8A) comprise the most reliable biomarkers for type 1 diabetes in both children and adults. Although Kuwait is the second among the top 10 countries with a high incidence rate of type 1 diabetes, there have been no proper diagnostic and prediction tools as per the World Health Organization. The Kuwaiti Type 1 Diabetes Study (KADS) was initiated to understand the disease pathogenesis as well as the HLA and anti-islet autoantibody profile of type 1 diabetes in Kuwait. Understanding the disease sequela in a homogenous gene pool and highly consanguineous population of Kuwaitis could help solve the challenges and pathogenesis, as well as hasten the prevention, of type 1 diabetes.

[Features of the development of latent autoimmune diabetes in adults (LADA)]

The study of the sociomedical problems of diabetes mellitus led to the discovery of latent autoimmune diabetes in adults (LADA), a special form of the disease. The slow onset of the disease, the clinical signs of type 2 diabetes mellitus concurrent with the autoantibody pancreatic β-cell destruction mechanism that is characteristic of type 1 diabetes. Genetic factors play an important role in the genesis of the disease. Insulitis concurrent with intact or hypertrophic islets of the gland originally develops morphologically. Subsequently, the phenomena of islet atrophy and sclerosis are progressive. The disease is typical for young people (generally those aged 25-35 years) with normal body mass index, low blood C-peptide levels, with antibodies against β-cells, primarily to glutamate decarboxylase, being detected. Insulin preparations should be used to treat these patients.

Fine Mapping of Glutamate Decarboxylase 65 Epitopes Reveals Dependency on Hydrophobic Amino Acids for Specific Interactions

Characterization of multiple antibody epitopes has revealed the necessity of specific groups of amino acid residues for reactivity. This applies to the majority of antibody-antigen interactions, where especially charged and hydrophilic amino acids have been reported to be essential for antibody reactivity. This study describes thorough characterization of glutamic acid decarboxylase (GAD) 65 antigenic epitopes, an immunodominant autoantigen in type 1 diabetes (T1D). As linear epitopes are sparsely described for GAD65 in T1D, we aimed to identify and thoroughly characterize two GAD65 antibodies using immunoassays. A monoclonal antibody recognized an epitope in the N-terminal domain of GAD65, ⁸FWSFGSE¹⁴, whereas a polyclonal antibody recognized two continuous epitopes in the C-terminal domain, corresponding to amino acids ⁵¹⁴RTLED⁵¹⁸ and ⁵⁴⁹PLGDKVNF⁵⁵⁶. Hydrophobic amino acids were essential for antibody reactivity, which was verified by competitive inhibition assays. Moreover, the epitopes were located in flexible linker regions and turn structures. These findings confirm the versatile nature of antibody-antigen interactions and describe potential continuous epitopes related to T1D, which predominantly have been proposed to be of discontinuous nature.

A Systematic Review of Childhood Diabetes Research in the Middle East Region

Background: Diabetes mellitus (DM) is a common chronic disorder in children and is caused by absolute or relative insulin deficiency, with or without insulin resistance. There are several different forms of childhood DM. Children can suffer from neonatal diabetes mellitus (NDM), type 1 diabetes (T1DM), type 2 diabetes (T2DM), Maturity Onset Diabetes of the Young (MODY), autoimmune monogenic, mitochondrial, syndromic and as yet unclassified forms of DM. The Middle East has one of the highest incidences of several types of DM in children; however, it is unclear whether pediatric diabetes is an active area of research in the Middle East and if ongoing, which research areas are of priority for DM in children. Objectives: To review the literature on childhood DM related to research in the Middle East, summarize results, identify opportunities for research and make observations and recommendations for collaborative studies in pediatric DM. Methods: We conducted a thorough and systematic literature review by adhering to a list recommended by PRISMA. We retrieved original papers written in English that focus on childhood DM research, using electronic bibliographic databases containing publications from the year 2000 until October 2018. For our final assessment, we retrieved 429 full-text articles and selected 95 articles, based on our inclusion and exclusion criteria. Results: Our literature review suggests that childhood DM research undertaken in the Middle East has focused mainly on reporting retrospective review of case notes, a few prospective case studies, systemic reviews, questionnaire-based studies, and case reports. These reported studies have focused mostly on the incidence/prevalence of different types of DM in childhood. No studies report on the establishment of National Childhood Diabetes Registries. There is a lack of consolidated studies focusing on national epidemiology data of different types of childhood DM (such as NDM, T1DM, T2DM, MODY, and syndromic forms) and no studies reporting on clinical trials in children with DM. Conclusions: Investing in and funding basic and translational childhood diabetes research and encouraging collaborative studies, will bring enormous benefits financially, economically, and socially for the whole of the Middle East region.

Glial fibrillary acidic protein (GFAP) is a novel biomarker for the prediction of autoimmune diabetes

Glial fibrillary acidic protein (GFAP) is expressed in peri-islet Schwann cells, as well as in glia cells, and has been reported to be an autoantigen candidate for type 1 diabetes mellitus (T1DM). We confirmed that the production of the autoantibodies GFAP and glutamic acid decarboxylase 65 (GAD65) was increased and inversely correlated with the concentration of secreted C peptide in female nonobese diabetic mice (T1DM model). Importantly, the development of T1DM in female nonobese diabetic mice at 30 wk of age was predicted by the positive GFAP autoantibody titer at 17 wk. The production of GFAP and GAD65 autoantibodies was also increased in KK-A^y mice [type 2 diabetes mellitus (T2DM) model]. In patients with diabetes mellitus, GFAP autoantibody levels were increased in patients with either T1DM or T2DM, and were significantly associated with GAD65 autoantibodies but not zinc transporter 8 autoantibodies. Furthermore, we identified a B-cell epitope of GFAP corresponding to the GFAP autoantibody in both mice and patients with diabetes. Thus, these results indicate that autoantibodies against GFAP could serve as a predictive marker for the development of overt autoimmune diabetes.-Pang, Z., Kushiyama, A., Sun, J., Kikuchi, T., Yamazaki, H., Iwamoto, Y., Koriyama, H., Yoshida, S., Shimamura, M., Higuchi, M., Kawano, T., Takami, Y., Rakugi, H., Morishita, R., Nakagumi, H. Glial fibrillary acidic protein (GFAP) is a novel biomarker for the prediction of autoimmune diabetes.

Approach to the Management of Autoimmunity in Primary Immunodeficiency

Primary immunodeficiency diseases (PIDs) consist of a genetically heterogeneous group of immune disorders that affect distinct elements of the immune system. PID patients are more prone to infections and non-infectious complications, particularly autoimmunity. The concomitance of immunodeficiency and autoimmunity appears to be paradoxical and leads to difficulty in the management of autoimmune complications in PID patients. Therefore, management of autoimmunity in patients with PID requires special considerations because dysregulations and dysfunctions of the immune system along with persistent inflammation impair the process of diagnosis and treatment.

Challenges of LADA Diagnosis and Treatment: Lessons From 2 Case Reports

Latent autoimmune diabetes in adults (LADA) is a subtype of autoimmune diabetes, which shares characteristics of both Type 1 and 2 diabetes (T1D and T2D), and for this reason, it is often confused with other types of diabetes, misdiagnosed, and inappropriately treated. Two cases were presented (41-year-old and 50-year-old females), one occasionally diagnosed during routine health checkup, the other one identified as having T2D, and as far as misclassified and not optimally treated. Now, after approximately 9 months of LADA diagnosis, the first patient has an optimal metabolic control while maintaining the values of glycated hemoglobin to around 7% with small doses of analogue insulin (lispro 4-6 UI) before meals and long acting insulin (glargine 4-6 UI) at bedtime. The second patient, after approximately 2 years from the LADA diagnosis, has an optimal metabolic control, with maintenance of glycated hemoglobin to around 6.5%, and stable C-peptide level (around 1.5 ng/mL), only with dietary and exercise habits. To avoid misclassification, any patient who does not fit the typical T2D profile, or with poor glycemic control, and who does not follow the expected clinical course, as become insulin dependent sooner than expected, should be investigated to exclude LADA. To define the best therapeutic approach, each patient must be evaluated and therapy tailored on his/her specific profile, considering as very low insulin doses may be effective to maintain a successful metabolic control and the only dietary approach may be sufficient until the insulin-secretory capacity remains good.

Correlations of Clusters of Non-Convulsive Seizure and Magnetic Resonance Imaging in a Case With GAD65-Positive Autoimmune Limbic Encephalitis

With the increased availability of laboratory tests, glutamic acid decarboxylase (GAD) antibody-positive limbic encephalitis has become an emerging diagnosis. The myriad symptoms of limbic encephalitis make the diagnosis challenging. Symptoms range from seizures, memory loss, dementia, confusion, to psychosis. We present a case of a 21-year-old female with GAD65 antibody-positive limbic encephalitis. The case is unique because the clinical course suggests that non-convulsive seizures are the major cause of this patient’s clinical manifestations. The following is the thesis: systemic autoimmune disease, associated with the GAD65 antibody, gives rise to seizures, in particular, non-convulsive seizures. Temporal lobes happen to be the most susceptible sites to develop seizures. The greater part of these seizures can be non-convulsive and hard to recognize without electroencephalogram (EEG) monitoring. The variable symptoms mirror the severity and locations of these seizures. The magnetic resonance imaging (MRI) signal abnormities in the bilateral hippocampus, fornix, and mammillary body correlate with the density of these seizures in the similar manner, which suggests it is secondary to post-ictal edema.

Diabetes-related autoantibodies in diabetic gastroparesis

BACKGROUND

Detection of islet autoantibodies [anti-glutamic acid decarboxylase antibody (GADA), anti-islet cell antibody (ICA), anti-insulin antibody (IAA)] in patients with diabetes usually indicates an autoimmune origin, suggesting type 1 diabetes (T1DM). The aim of our study was to determine whether islet autoantibodies are present in patients with diabetic gastroparesis and whether they associate with delayed gastric emptying, severity of GI symptoms, or diagnosed type of diabetes.

METHODS

Patients with diabetic gastroparesis completed: (1) Demographic Questionnaire assessing type of diabetes, associated symptoms and control of glucose and (2) Patient Assessment of GI Symptoms assessing symptoms severity. Blood was drawn for GADA, anti-islet cell ICA-IAA, and Hgb-A1c. Medical records were reviewed for gastric emptying tests and to confirm type of diabetes.

RESULTS

Sixteen patients (12 T1DM; 4 diagnosed T2DM) with diabetic gastroparesis were evaluated. Six of the 16 patients tested positive for GADA, but none were positive for either ICA or IAA. Five of 12 T1DM patients had positive GADA, compared to one of four diagnosed as T2DM. The presence of antibodies was associated with the age of onset of gastroparesis symptoms, but not related to gastric emptying delay, symptom severity, HBA1c levels, or age.

CONCLUSIONS

This pilot study demonstrated that of the three tested antibodies in long-term diabetic gastroparesis patients, GADA was the most prevalent positive antibody with no detection of ICA or IAA. Positive GADA was seen in 42 % of T1DM compared to 25 % of phenotypic T2DM. However, the presence of antibody was not associated with severity of gastric emptying or GI symptoms. Thus, detection of an autoimmune form of diabetes, primarily T1DM, should be investigated using GADA.

Advances in our understanding of the pathophysiology of Type 1 diabetes: lessons from the NOD mouse

T1D (Type 1 diabetes) is an autoimmune disease caused by the immune-mediated destruction of pancreatic β-cells. Studies in T1D patients have been limited by the availability of pancreatic samples, a protracted pre-diabetic phase and limitations in markers that reflect β-cell mass and function. The NOD (non-obese diabetic) mouse is currently the best available animal model of T1D, since it develops disease spontaneously and shares many genetic and immunopathogenic features with human T1D. Consequently, the NOD mouse has been extensively studied and has made a tremendous contribution to our understanding of human T1D. The present review summarizes the key lessons from NOD mouse studies concerning the genetic susceptibility, aetiology and immunopathogenic mechanisms that contribute to autoimmune destruction of β-cells. Finally, we summarize the potential and limitations of immunotherapeutic strategies, successful in NOD mice, now being trialled in T1D patients and individuals at risk of developing T1D.