A Hemoglobinopathy That Produces an Array of Different Hemoglobin A1c Values.

Hemoglobin A1c (HbA1c) refers to non-enzymatically glycated hemoglobin and reflects the patient's glycemic status over approximately 3 months. An elevated HbA1c over 6.5% National Glycohemoglobin Standardization Program (NGSP) (48 mmol/mol the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC)) can be used to diagnose diabetes mellitus. In our laboratory, HbA1c is determined by ion-exchange chromatography which has the advantage of detecting common Hb variants such as Hb S, C, E and D without adversely affecting the HbA1c determination. Certain homozygous or compound heterozygous hemoglobinopathies such as homozygous sickle disease and Hb SC disease can significantly lower the HbA1c by reducing red cell lifespan. Occasionally however, rare and mostly benign hemoglobinopathies can interfere with this technique resulting in an apparent elevation of HbA1c in an otherwise non-diabetic patient. In this report, we describe such a hemoglobinopathy termed Hb Wayne that resulted in a significant HbA1c elevation in a normoglycemic individual. HbA1c was determined by multiple methods including immunoassay, a modified capillary electrophoresis and an alternative ion-exchange system. These techniques yielded significantly lower A1c results, more in keeping with the patient's clinical background. The alternative ion-exchange system resulted in a low A1c that was qualified by warning flags on the chromatogram that indicated the result was not reportable. The hemoglobinopathy in question, Hb Wayne, is a frameshift mutation in the alpha globin gene that results in an extended alpha globin polypeptide that can form two variants Hb Wayne I and Wayne II. Hb Wayne is a clinically silent asymptomatic disorder with no hematologic consequences. The artifactual elevation of HbA1c is, in contrast, very significant because it may result in a misdiagnosis of diabetes mellitus leading to unnecessary treatment. In this report, we compare our findings with other descriptions of Hb Wayne in the literature and corroborate a number of previous observations and conclusions.

Impaired islet function and normal exocrine enzyme secretion occur with low inter-regional variation in type 1 diabetes.

Histopathological heterogeneity in the human pancreas is well documented; however, functional evidence at the tissue level is scarce. Herein, we investigate in situ glucose-stimulated islet and carbachol-stimulated acinar cell secretion across the pancreas head (PH), body (PB), and tail (PT) regions in donors without diabetes (ND; n = 15), positive for one islet autoantibody (1AAb+; n = 7), and with type 1 diabetes (T1D; <14 months duration, n = 5). Insulin, glucagon, pancreatic amylase, lipase, and trypsinogen secretion along with 3D tissue morphometrical features are comparable across regions in ND. In T1D, insulin secretion and beta-cell volume are significantly reduced within all regions, while glucagon and enzymes are unaltered. Beta-cell volume is lower despite normal insulin secretion in 1AAb+, resulting in increased volume-adjusted insulin secretion versus ND. Islet and acinar cell secretion in 1AAb+ are consistent across the PH, PB, and PT. This study supports low inter-regional variation in pancreas slice function and, potentially, increased metabolic demand in 1AAb+.

Serum from pregnant donors induces human beta cell proliferation.

Pancreatic beta cells are among the slowest replicating cells in the human body and have not been observed to increase in number except during the fetal and neonatal period, in cases of obesity, during puberty, as well as during pregnancy. Pregnancy is associated with increased beta cell mass to meet heightened insulin demands. This phenomenon raises the intriguing possibility that factors present in the serum of pregnant individuals may stimulate beta cell proliferation and offer insights into expansion of the beta cell mass for treatment and prevention of diabetes. The primary objective of this study was to test the hypothesis that serum from pregnant donors contains bioactive factors capable of inducing human beta cell proliferation. An immortalized human beta cell line with protracted replication (EndoC-ßH1) was cultured in media supplemented with serum from pregnant and non-pregnant female and male donors and assessed for differences in proliferation. This experiment was followed by assessment of proliferation of primary human beta cells. Sera from five out of six pregnant donors induced a significant increase in the proliferation rate of EndoC-ßH1 cells. Pooled serum from the cohort of pregnant donors also increased the rate of proliferation in primary human beta cells. This study demonstrates that serum from pregnant donors stimulates human beta cell proliferation. These findings suggest the existence of pregnancy-associated factors that can offer novel avenues for beta cell regeneration and diabetes prevention strategies. Further research is warranted to elucidate the specific factors responsible for this effect.

An antigen-specific immunotherapeutic, AKS-107, deletes insulin-specific B cells and prevents murine autoimmune diabetes.

Introduction: The antigen-presenting cell function of insulin-reactive B cells promotes type 1 diabetes (T1D) in non-obese diabetic (NOD) mice by stimulating pathogenic T cells leading to destruction of insulin-producing ß-cells of pancreatic islets. Methods/Results: To target insulin-reactive B cells, AKS-107, a human IgG1 Fc molecule fused with human insulin A and B chains, was engineered to retain conformational insulin epitopes that bound mouse and human B cell receptors but prevented binding to the insulin metabolic receptor. AKS-107 Fc-mediated deletion of insulin-reactive B cells was demonstrated via ex vivo and in vivo experiments with insulin-reactive B cell receptor transgenic mouse strains, VH125Tg/NOD and Tg125(H+L)/NOD. As an additional immune tolerance feature, the Y16A mutation of the insulin B(9-23) dominant T cell epitope was engineered into AKS-107 to suppress activation of insulin-specific T cells. In mice and non-human primates, AKS-107 was well-tolerated, non-immunogenic, did not cause hypoglycemia even at high doses, and showed an expectedly protracted pharmacokinetic profile. AKS-107 reproducibly prevented spontaneous diabetes from developing in NOD and VH125Tg/NOD mice that persisted for months after cessation of treatment, demonstrating durable immune tolerance. Discussion: These preclinical outcomes position AKS-107 for clinical development in T1D prevention settings.

Impaired islet function with normal exocrine enzyme secretion is consistent across the head, body, and tail pancreas regions in type 1 diabetes.

Histopathological heterogeneity in human pancreas has been well documented; however, functional evidence at the tissue level is scarce. Herein we investigated in situ glucose-stimulated islet and carbachol-stimulated acinar cell secretion across the pancreas head (PH), body (PB), and tail (PT) regions in no diabetes (ND, n=15), single islet autoantibody-positive (1AAb+, n=7), and type 1 diabetes donors (T1D, <14 months duration, n=5). Insulin, glucagon, pancreatic amylase, lipase, and trypsinogen secretion along with 3D tissue morphometrical features were comparable across the regions in ND. In T1D, insulin secretion and beta-cell volume were significantly reduced within all regions, while glucagon and enzymes were unaltered. Beta-cell volume was lower despite normal insulin secretion in 1AAb+, resulting in increased volume-adjusted insulin secretion versus ND. Islet and acinar cell secretion in 1AAb+ were consistent across PH, PB and PT. This study supports low inter-regional variation in pancreas slice function and potentially, increased metabolic demand in 1AAb+.

DNA Methylation-Based Assessment of Cell Composition in Human Pancreas and Islets.

Assessment of pancreas cell type composition is crucial to the understanding of the genesis of diabetes. Current approaches use immunodetection of protein markers, for example, insulin as a marker of ß-cells. A major limitation of these methods is that protein content varies in physiological and pathological conditions, complicating the extrapolation to actual cell number. Here, we demonstrate the use of cell type-specific DNA methylation markers for determining the fraction of specific cell types in human islet and pancreas specimens. We identified genomic loci that are uniquely demethylated in specific pancreatic cell types and applied targeted PCR to assess the methylation status of these loci in tissue samples, enabling inference of cell type composition. In islet preparations, normalization of insulin secretion to ß-cell DNA revealed similar ß-cell function in pre-type 1 diabetes (T1D), T1D, and type 2 diabetes (T2D), which was significantly lower than in donors without diabetes. In histological pancreas specimens from recent-onset T1D, this assay showed ß-cell fraction within the normal range, suggesting a significant contribution of ß-cell dysfunction. In T2D pancreata, we observed increased α-cell fraction and normal ß-cell fraction. Methylation-based analysis provides an accurate molecular alternative to immune detection of cell types in the human pancreas, with utility in the interpretation of insulin secretion assays and the assessment of pancreas cell composition in health and disease.

Low-Dose Antithymocyte Globulin: A Pragmatic Approach to Treating Stage 2 Type 1 Diabetes.

OBJECTIVE: Low-dose antithymocyte globulin (ATG) (2.5 mg/kg) preserves C-peptide and reduces HbA1c in new-onset stage 3 type 1 diabetes, yet efficacy in delaying progression from stage 2 to stage 3 has not been evaluated. RESEARCH DESIGN AND METHODS: Children (n = 6) aged 5-14 years with stage 2 type 1 diabetes received off-label, low-dose ATG. HbA1c, C-peptide, continuous glucose monitoring, insulin requirements, and side effects were followed for 18-48 months. RESULTS: Three subjects (50%) remained diabetes free after 1.5, 3, and 4 years of follow-up, while three developed stage 3 within 1-2 months after therapy. Eighteen months posttreatment, even disease progressors demonstrated near-normal HbA1c (5.1% [32 mmol/mol], 5.6% [38 mmol/mol], and 5.3% [34 mmol/mol]), time in range (93%, 88%, and 98%), low insulin requirements (0.17, 0.18, and 0.34 units/kg/day), and robust C-peptide 90 min after mixed meal (1.3 ng/dL, 2.3 ng/dL, and 1.4 ng/dL). CONCLUSIONS: These observations support additional prospective studies evaluating ATG in stage 2 type 1 diabetes.