Susanne M. Cabrera

Islet β-Cell Endoplasmic Reticulum Stress Precedes the Onset of Type 1 Diabetes in the Nonobese Diabetic Mouse Model

Type 1 diabetes is preceded by islet β-cell dysfunction, but the mechanisms leading to β-cell dysfunction have not been rigorously studied. Because immune cell infiltration occurs prior to overt diabetes, we hypothesized that activation of inflammatory cascades and appearance of endoplasmic reticulum (ER) stress in β-cells contributes to insulin secretory defects. Prediabetic nonobese diabetic (NOD) mice and control diabetes-resistant NOD-SCID and CD1 strains were studied for metabolic control and islet function and gene regulation. Prediabetic NOD mice were relatively glucose intolerant and had defective insulin secretion with elevated proinsulin:insulin ratios compared with control strains. Isolated islets from NOD mice displayed age-dependent increases in parameters of ER stress, morphologic alterations in ER structure by electron microscopy, and activation of nuclear factor-κB (NF-κB) target genes. Upon exposure to a mixture of proinflammatory cytokines that mimics the microenvironment of type 1 diabetes, MIN6 β-cells displayed evidence for polyribosomal runoff, a finding consistent with the translational initiation blockade characteristic of ER stress. We conclude that β-cells of prediabetic NOD mice display dysfunction and overt ER stress that may be driven by NF-κB signaling, and strategies that attenuate pathways leading to ER stress may preserve β-cell function in type 1 diabetes.

Molecular signatures differentiate immune states in type 1 diabetic families.

Mechanisms associated with type 1 diabetes (T1D) development remain incompletely defined. Using a sensitive array-based bioassay where patient plasma is used to induce transcriptional responses in healthy leukocytes, we previously reported disease-specific, partially interleukin (IL)-1−dependent signatures associated with preonset and recent onset (RO) T1D relative to unrelated healthy control subjects (uHC). To better understand inherited susceptibility in T1D families, we conducted cross-sectional and longitudinal analyses of healthy autoantibody-negative (AA−) high HLA−risk siblings (HRS) (DR3 and/or DR4) and AA− low HLA−risk siblings (LRS) (non-DR3/non-DR4). Signatures, scored with a novel ontology-based algorithm, and confirmatory studies differentiated the RO T1D, uHC, HRS, and LRS plasma milieus. Relative to uHC, T1D family members exhibited an elevated inflammatory state, consistent with innate receptor ligation that was independent of HLA, AA, or disease status and included elevated plasma IL-1α, IL-12p40, CCL2, CCL3, and CCL4 levels. Longitudinally, signatures of T1D progressors exhibited increasing inflammatory bias. Conversely, HRS possessing decreasing AA titers revealed emergence of an IL-10/transforming growth factor-β−mediated regulatory state that paralleled temporal increases in peripheral activated CD4+/CD45RA−/FoxP3high regulatory T-cell frequencies. In AA− HRS, the familial innate inflammatory state also was temporally supplanted by immunoregulatory processes, suggesting a mechanism underlying the decline in T1D susceptibility with age.

Targeting Regulatory T Cells in the Treatment of Type 1 Diabetes Mellitus

Type 1 diabetes mellitus (T1DM) is a T cell-mediated autoimmune disease resulting in islet β cell destruction, hypoinsulinemia, and severely altered glucose homeostasis. T1DM has classically been attributed to the pathogenic actions of auto-reactive effector T cells(Teffs) on the β cell. Recent literature now suggests that a failure of a second T cell subtype, known as regulatory T cells (Tregs), plays a critical role in the development of T1DM. During immune homeostasis, Tregs counterbalance the actions of autoreactive Teff cells, thereby participating in peripheral tolerance. An imbalance in the activity between Teff and Tregs may be crucial in the breakdown of peripheral tolerance, leading to the development of T1DM. In this review, we summarize our current understanding of Treg function in health and in T1DM, and examine the effect of experimental therapies for T1DM on Treg cell number and function in both mice and humans.

Age of thelarche and menarche in contemporary US females: a cross-sectional analysis

Abstract Aim: A recent secular trend towards earlier thelarche has been suggested. The aim of this study is to examine normative ages of thelarche and menarche in contemporary US females. Methods: Trained physicians documented Tanner breast stage by observation in a cross-sectional cohort. Age of menarche was self-reported. The subjects were healthy female children and adolescents. The mean age of thelarche was determined by probit analysis and the mean age of menarche was determined by using a normal time-to-event model. Results: Mean age of thelarche was 9.7 years among 610 females aged 3.0–17.9 years (70% non-Hispanic Caucasian (NHC), 14% African-Americans, 7% Hispanic, 9% “other”). The mean age of menarche was 12.8 years for NHC, with African-Americans having menarche 0.6 years earlier. Conclusions: Thelarche occurred earlier than recently reported, while age of menarche remained unchanged, this supported a persistent secular trend towards earlier thelarche but stable age of menarche. This suggests that the observed thelarche is gonadotropin-independent or the tempo of pubertal advancement has slowed.

Innate inflammation in type 1 diabetes.

Type 1 diabetes mellitus (T1D) is an autoimmune disease often diagnosed in childhood that results in pancreatic β-cell destruction and life-long insulin dependence. T1D susceptibility involves a complex interplay between genetic and environmental factors and has historically been attributed to adaptive immunity, although there is now increasing evidence for a role of innate inflammation. Here, we review studies that define a heightened age-dependent innate inflammatory state in T1D families that is paralleled with high fidelity by the T1D-susceptible biobreeding rat. Innate inflammation may be driven by changes in interactions between the host and environment, such as through an altered microbiome, intestinal hyperpermeability, or viral exposures. Special focus is put on the temporal measurement of plasma-induced transcriptional signatures of recent-onset T1D patients and their siblings as well as in the biobreeding rat as it defines the natural history of innate inflammation. These sensitive and comprehensive analyses have also revealed that those who successfully managed T1D risk develop an age-dependent immunoregulatory state, providing a possible mechanism for the juvenile nature of T1D. Therapeutic targeting of innate inflammation has been proven effective in preventing and delaying T1D in rat models. Clinical trials of agents that suppress innate inflammation have had more modest success, but efficacy may be improved by the addition of combinatorial approaches that target other aspects of T1D pathogenesis. An understanding of innate inflammation and mechanisms by which this susceptibility is both potentiated and mitigated offers important insight into T1D progression and avenues for therapeutic intervention.

Blood-based signatures in type 1 diabetes

Type 1 diabetes mellitus is one of the most common chronic diseases in childhood. It develops through autoimmune destruction of the pancreatic beta cells and results in lifelong dependence on exogenous insulin. The pathogenesis of type 1 diabetes involves a complex interplay of genetic and environmental factors and has historically been attributed to aberrant adaptive immunity; however, there is increasing evidence for a role of innate inflammation. Over the past decade new methodologies for the analysis of nucleic acid and protein signals have been applied to type 1 diabetes. These studies are providing a new understanding of type 1 diabetes pathogenesis and have the potential to inform the development of new biomarkers for predicting diabetes onset and monitoring therapeutic interventions. In this review we will focus on blood-based signatures in type 1 diabetes, with special attention to both direct transcriptomic analyses of whole blood and immunocyte subsets, as well as plasma/serum-induced transcriptional signatures. Attention will also be given to proteomics, microRNA assays and markers of beta cell death. We will also discuss the results of blood-based profiling in type 1 diabetes within the context of the genetic and environmental factors implicated in the natural history of autoimmune diabetes.

Effects of combination therapy with dipeptidyl peptidase-IV and histone deacetylase inhibitors in the non-obese diabetic mouse model of type 1 diabetes

Type 1 diabetes (T1D) results from T helper type 1 (Th1)‐mediated autoimmune destruction of insulin‐producing β cells. Novel experimental therapies for T1D target immunomodulation, β cell survival and inflammation. We examined combination therapy with the dipeptidyl peptidase‐IV inhibitor MK‐626 and the histone deacetylase inhibitor vorinostat in the non‐obese diabetic (NOD) mouse model of T1D. We hypothesized that combination therapy would ameliorate T1D by providing protection from β cell inflammatory destruction while simultaneously shifting the immune response towards immune‐tolerizing regulatory T cells (Tregs). Although neither mono‐ nor combination therapies with MK‐626 and vorinostat caused disease remission in diabetic NOD mice, the combination of MK‐626 and vorinostat increased β cell area and reduced the mean insulitis score compared to diabetic control mice. In prediabetic NOD mice, MK‐626 monotherapy resulted in improved glucose tolerance, a reduction in mean insulitis score and an increase in pancreatic lymph node Treg percentage, and combination therapy with MK‐626 and vorinostat increased pancreatic lymph node Treg percentage. We conclude that neither single nor combination therapies using MK‐626 and vorinostat induce diabetes remission in NOD mice, but combination therapy appears to have beneficial effects on β cell area, insulitis and Treg populations. Combinations of vorinostat and MK‐626 may serve as beneficial adjunctive therapy in clinical trials for T1D prevention or remission.

Incidence and Characteristics of Pseudoprecocious Puberty Because of Severe Primary Hypothyroidism

Severe primary hypothyroidism is a presumed rare cause of pseudoprecocious puberty (PsPP). Here, we report a 24% incidence of PsPP among 33 children with profound hypothyroidism. Those with PsPP were older and trended toward a higher thyroid stimulating hormone. Increased awareness of PsPP can hasten diagnosis and appropriate treatment.

Interleukin‐1 antagonism moderates the inflammatory state associated with Type 1 diabetes during clinical trials conducted at disease onset

It was hypothesized that IL‐1 antagonism would preserve β‐cell function in new onset Type 1 diabetes (T1D). However, the Anti‐Interleukin‐1 in Diabetes Action (AIDA) and TrialNet Canakinumab (TN‐14) trials failed to show efficacy of IL‐1 receptor antagonist (IL‐1Ra) or canakinumab, as measured by stimulated C‐peptide response. Additional measures are needed to define immune state changes associated with therapeutic responses. Here, we studied these trial participants with plasma‐induced transcriptional analysis. In blinded analyses, 70.2% of AIDA and 68.9% of TN‐14 participants were correctly called to their treatment arm. While the transcriptional signatures from the two trials were distinct, both therapies achieved varying immunomodulation consistent with IL‐1 inhibition. On average, IL‐1 antagonism resulted in modest normalization relative to healthy controls. At endpoint, signatures were quantified using a gene ontology‐based inflammatory index, and an inverse relationship was observed between measured inflammation and stimulated C‐peptide response in IL‐1Ra‐ and canakinumab‐treated patients. Cytokine neutralization studies showed that IL‐1α and IL‐1β additively contribute to the T1D inflammatory state. Finally, analyses of baseline signatures were indicative of later therapeutic response. Despite the absence of clinical efficacy by IL‐1 antagonist therapy, transcriptional analysis detected immunomodulation and may yield new insight when applied to other clinical trials.

Testosterone exposure in childhood: discerning pathology from physiology.

Introduction: Testosterone (T) drives normal male sexual development both in utero and at puberty. Aberrant T exposure manifests as virilization of a female fetus, contrasexual precocity in girls, and isosexual precocity in boys. Evidence of pathologic T exposure warrants a prompt evaluation. Areas covered: The authors introduce the topic of T exposure in children by reviewing its physiology in the fetus and during childhood and adolescence. Pathologic conditions leading to virilization of a female fetus as well as androgen-mediated gonadotropin-independent precocious puberty in both genders are then discussed. The authors finish by noting exogenous T exposure in children and adolescents, focusing specifically on secondary exposure to topical T preparations. Expert opinion: Contrasexual precocity in a girl or sexual precocity in a boy should prompt evaluation for causes of gonadotropin-independent pubertal changes. Initial biochemical evaluation includes a bone age, T, 17-hydroxyprogesterone, androstenedione, dehydroepiandrosterone sulfate (DHEA-S) and high sensitivity gonadotropin levels. The provider must query exposure to topical androgen-containing preparations as unintentional secondary exposure to topical T must be considered. Hyperandrogenism is temporally related to exposure of topical T and removal of exposure results in a marked decrease in serum T as well as resolution or stabilization of the signs and symptoms.