Search

Primary cilia are specialized cell-surface organelles that mediate sensory perception and, in contrast to motile cilia and flagella, are thought to lack motility function. Here, we show that primary cilia in human and mouse pancreatic islets exhibit movement that is required for glucose-dependent insulin secretion. Islet primary cilia contain motor proteins conserved from those found in classic motile cilia, and their three-dimensional motion is dynein-driven and dependent on adenosine 5′-triphosphate and glucose metabolism. Inhibition of cilia motion blocks beta cell calcium influx and insulin secretion. Human beta cells have enriched ciliary gene expression, and motile cilia genes are altered in type 2 diabetes. Our findings redefine primary cilia as dynamic structures having both sensory and motile function and establish that pancreatic islet cilia movement plays a regulatory role in insulin secretion.

AimsSpatially-organised increases in cytosolic Ca2+within pancreatic beta cells in the pancreatic islet underlie the stimulation of insulin secretion by high glucose. Recent data have revealed the existence of subpopulations of beta cells including “leaders” which initiate Ca2+waves. Whether leader cells possess unique molecular features, or localisation, is unknown.Main methodsHigh speed confocal Ca2+imaging was used to identify leader cells and connectivity analysis, running under MATLAB and Python, to identify highly connected “hub” cells. To explore transcriptomic differences between beta cell sub-groups, individual leaders or followers were labelled by photo-activation of the cryptic fluorescent protein PA-mCherry and subjected to single cell RNA sequencing (“Flash-Seq”).Key findingsDistinct Ca2+wave types were identified in individual islets, with leader cells present in 73 % (28 of 38 islets imaged). Scale-free, power law-adherent behaviour was also observed in 29% of islets, though “hub” cells in these islets did not overlap with leaders. Transcripts differentially expressed (295; padjvsfollower cells. Leader cells were also located significantly closer to delta cells in Euclidian space than were follower cells.SignificanceThe existence of both a discrete transcriptome and unique localisation implies a role for these features in defining the specialized function of leaders. Specifically, these data raise the possibility of altered signalling from delta cells towards somatostatin receptors present on leader cell cilia.

Significance The primary cilium is a small subcompartment of the cell but has powerful influence on pancreatic islet function. In this study, we find a critical role for cilia in regulating β-cell function and energy metabolism. Importantly, the deletion of β-cell cilia disrupts intercellular communication and leads to islet dysfunction and diabetes, as seen in a number of human ciliopathy syndromes. These results should help elucidate pathophysiology of human ciliopathy and aid the development of pharmacologic agents targeting primary cilia that may lead to a more effective treatment for human diabetes., Pancreatic islets regulate glucose homeostasis through coordinated actions of hormone-secreting cells. What underlies the function of the islet as a unit is the close approximation and communication among heterogeneous cell populations, but the structural mediators of islet cellular cross talk remain incompletely characterized. We generated mice specifically lacking β-cell primary cilia, a cellular organelle that has been implicated in regulating insulin secretion, and found that the β-cell cilia are required for glucose sensing, calcium influx, insulin secretion, and cross regulation of α- and δ-cells. Protein expression profiling in islets confirms perturbation in these cellular processes and reveals additional targets of cilia-dependent signaling. At the organism level, the deletion of β-cell cilia disrupts circulating hormone levels, impairs glucose homeostasis and fuel usage, and leads to the development of diabetes. Together, these findings demonstrate that primary cilia not only orchestrate β-cell–intrinsic activity but also mediate cross talk both within the islet and from islets to other metabolic tissues, thus providing a unique role of cilia in nutrient metabolism and insight into the pathophysiology of diabetes.

AIMS: Spatially-organized increases in cytosolic Ca2+ within pancreatic beta cells in the pancreatic islet underlie the stimulation of insulin secretion by high glucose. Recent data have revealed the existence of subpopulations of beta cells including "leaders" which initiate Ca2+ waves. Whether leader cells possess unique molecular features, or localisation, is unknown. MAIN METHODS: High speed confocal Ca2+ imaging was used to identify leader cells and connectivity analysis, running under MATLAB and Python, to identify highly connected "hub" cells. To explore transcriptomic differences between beta cell sub-groups, individual leaders or followers were labelled by photo-activation of the cryptic fluorescent protein PA-mCherry and subjected to single cell RNA sequencing ("Flash-Seq"). KEY FINDINGS: Distinct Ca2+ wave types were identified in individual islets, with leader cells present in 73 % (28 of 38 islets imaged). Scale-free, power law-adherent behaviour was also observed in 29 % of islets, though "hub" cells in these islets did not overlap with leaders. Transcripts differentially expressed (295; padj

Primary cilia are specialized cell-surface organelles that mediate sensory perception and, in contrast to motile cilia and flagella, are thought to lack motility function. Here we show that primary cilia in pancreatic beta cells exhibit movement that is required for glucose-dependent insulin secretion. Beta cell cilia contain motor proteins conserved from those found in classic motile cilia, and their 3D motion is dynein-driven and dependent on ATP and glucose metabolism. Inhibition of cilia motion blocks beta cell calcium influx and insulin secretion. Beta cells from humans with type 2 diabetes have altered expression of cilia motility genes. Our findings redefine primary cilia as dynamic structures possessing both sensory and motile function and establish that pancreatic beta cell cilia movement plays a critical role in controlling insulin secretion.

Maintenance of functional β‐cell mass is critical to preventing diabetes, but the physiological mechanisms that cause β‐cell populations to thrive or fail in the context of obesity are unknown. High fat‐fed SM/J mice spontaneously transition from hyperglycemic‐obese to normoglycemic‐obese with age, providing a unique opportunity to study β‐cell adaptation. Here, we characterize insulin homeostasis, islet morphology, and β‐cell function during SM/J’s diabetic remission. As they resolve hyperglycemia, obese SM/J mice dramatically increase circulating and pancreatic insulin levels while improving insulin sensitivity. Immunostaining of pancreatic sections reveals that obese SM/J mice selectively increase β‐cell mass but not α‐cell mass. Obese SM/J mice do not show elevated β‐cell mitotic index, but rather elevated α‐cell mitotic index. Functional assessment of isolated islets reveals that obese SM/J mice increase glucose‐stimulated insulin secretion, decrease basal insulin secretion, and increase islet insulin content. These results establish that β‐cell mass expansion and improved β‐cell function underlie the resolution of hyperglycemia, indicating that obese SM/J mice are a valuable tool for exploring how functional β‐cell mass can be recovered in the context of obesity., High fat‐fed SM/J mice spontaneously transition from hyperglycemic‐obese to normoglycemic‐obese with age, providing a unique opportunity to study β‐cell adaptation. Here we characterize insulin homeostasis, islet morphology, and β‐cell function during SM/J's diabetic remission.

Maintenance of functional β-cell mass is critical to preventing diabetes, but the physiological mechanisms that cause β-cell populations to thrive or fail in the context of obesity are unknown. High fat-fed SM/J mice spontaneously transition from hyperglycemic-obese to normoglycemic-obese with age, providing a unique opportunity to study β-cell adaptation. Here, we characterize insulin homeostasis, islet morphology, and β-cell function during SM/J’s diabetic remission. As they resolve hyperglycemia, obese SM/J mice dramatically increase circulating and pancreatic insulin levels while improving insulin sensitivity. Immunostaining of pancreatic sections reveals that obese SM/J mice selectively increase β-cell mass but not α-cell mass. Obese SM/J mice do not show elevated β-cell mitotic index, but rather elevated α-cell mitotic index. Functional assessment of isolated islets reveals that obese SM/J mice increase glucose stimulated insulin secretion, decrease basal insulin secretion, and increase islet insulin content. These results establish that β-cell mass expansion and improved β-cell function underlie the resolution of hyperglycemia, indicating that obese SM/J mice are a valuable tool for exploring how functional β-cell mass can be recovered in the context of obesity.

The islet of Langerhans plays a key role in glucose homeostasis through regulated secretion of the hormones insulin and glucagon. Islet research has focused on the insulin-secreting β-cells, even though aberrant glucagon secretion from α-cells also contributes to the etiology of diabetes. Despite its importance, the mechanisms controlling glucagon secretion remain controversial. Proper α-cell function requires the islet milieu, where β- and δ-cells drive and constrain α-cell dynamics. The response of glucagon to glucose is similar between isolated islets and that measured in vivo, so it appears that the glucose dependence requires only islet-intrinsic factors and not input from blood flow or the nervous system. Elevated intracellular free Ca(2+) is needed for α-cell exocytosis, but interpreting Ca(2+) data is tricky since it is heterogeneous among α-cells at all physiological glucose levels. Total Ca(2+) activity in α-cells increases slightly with glucose, so Ca(2+)may serve a permissive, rather than regulatory, role in glucagon secretion. On the other hand, cAMP is a more promising candidate for controlling glucagon secretion and is itself driven by paracrine signaling from β- and δ-cells. Another pathway, juxtacrine signaling through the α-cell EphA receptors, stimulated by β-cell ephrin ligands, leads to a tonic inhibition of glucagon secretion. We discuss potential combinations of Ca(2+), cAMP, paracrine and juxtacrine factors in the regulation of glucagon secretion, focusing on recent data in the literature that might unify the field towards a quantitative understanding of α-cell function.

Pernicious anemia (PA) develops from atrophic gastritis due to autoimmune destruction of parietal cells and results in achlorhydria, vitamin B12 and iron deficiencies, anemia, neurologic deficits, and premalignant and malignant stomach lesions. We report the presentation, diagnosis and gastric complications of PA in patients from an endocrinology practice.Thirty-four patients (31 female, 3 male) with PA who underwent esophagogastroduodenoscopy (EGD) or gastrectomy were identified. Pertinent clinical, laboratory, and pathology findings were reviewed and summarized.The mean age of patients was 58.6 ± 14.2 years; the onset of PA was age 50.2 ± 15.3 years. Anemia reflected vitamin B12 and/or iron deficiencies. Parietal cell antibodies (PCA) were detected in 97% of patients, and intrinsic factor blocking antibody (IFBA) was found in 52%. Fasting gastrin and chromogranin A levels were elevated (1,518.0 ± 1,588.3 pg/mL, and 504.9.1 ± 1,524.9 ng/mL respectively). Autoimmune or immunologic diseases (AIDs) were present in 32/34 patients. Stomach pathology showed premalignant or malignant lesions in 26 patients, including gastric neuroendocrine tumors (GNETs) in 6 and adenocarcinoma in 1. One patient presented with neurologic symptoms and subacute combined degeneration of the posterior column of the spinal cord.PA should be suspected in patients with unexplained anemia or neurologic symptoms. The diagnosis of PA relies on fasting gastrin and gastric auto-antibody testing, in addition to hematologic evaluation. EGD with measurement of gastric pH and biopsies of the fundus and antrum identifies patients with achlorhydria, atrophic gastritis, and premalignant and malignant stomach lesions. EGD surveillance of patients with high-risk stomach lesions is recommended.AID = autoimmune or immunologic disease; EGD = esophagogastroduodenoscopy; GNET = gastric neuroendocrine tumor; IFBA = intrinsic factor blocking antibody; PA = pernicious anemia; PCA = parietal cell antibody; T1D = type 1 diabetes.

Background The prevalence of systemic rheumatic diseases (SRDs) in T1DM has not been described. Method This observational study compares SRD prevalence across age, race, and gender in 1,212 adults with T1DM. Findings There is an age-dependent enrichment of SRDs in women with T1DM: 9.2% prevalence in women overall and 14% in women over age 50. Conclusion Clinicians taking care of older women with T1DM should monitor for these SRDs.

BACKGROUND. The cytokine IL-7 is critical for T cell development and function. We performed a Phase Ib study in patients with type 1 diabetes (T1D) to evaluate how blockade of IL-7 would affect immune cells and relevant clinical responses. METHODS. Thirty-seven subjects with T1D received s.c. RN168, a monoclonal antibody that blocks the IL -7 receptor α (IL7Rα) in a dose-escalating study. RESULTS. Between 90% and 100% IL-7R occupancy and near-complete inhibition of pSTAT5 was observed at doses of RN168 1 mg/kg every other week (Q2wk) and greater. There was a significant decline in CD4(+) and CD8(+) effector and central memory T cells and CD4(+) naive cells, but there were fewer effects on CD8(+) naive T cells. The ratios of Tregs to CD4(+) or CD8(+) effector and central memory T cells versus baseline were increased. RNA sequencing analysis showed downmodulation of genes associated with activation, survival, and differentiation of T cells. Expression of the antiapoptotic protein Bcl-2 was reduced. The majority of treatment-emergent adverse events (TEAEs) were mild and not treatment related. Four subjects became anti–EBV IgG(+) after RN168, and 2 had symptoms of active infection. The immunologic response to tetanus toxoid was preserved at doses of 1 and 3 mg/kg Q2wk but reduced at higher doses. CONCLUSIONS. This trial shows that, at dosages of 1–3 mg/kg, RN168 selectively inhibits the survival and activity of memory T cells while preserving naive T cells and Tregs. These immunologic effects may serve to eliminate pathologic T cells in autoimmune diseases. TRIAL REGISTRATION. NCT02038764. FUNDING. Pfizer Inc.

OBJECTIVE Type 1 diabetes (T1DM) is associated with other autoimmune diseases (AIDs), which may have serious health consequences. The epidemiology of AIDs in T1DM is not well defined in adults with T1DM. In this cross-sectional cohort study, we sought to characterize the incident ages and prevalence of AIDs in adults with T1DM across a wide age spectrum. RESEARCH DESIGN AND METHODS A total of 1,212 adults seen at the Washington University Diabetes Center from 2011 to 2018 provided informed consent for the collection of their age, sex, race, and disease onset data. We performed paired association analyses based on age at onset of T1DM. Multivariate logistic regression was used to evaluate the independent effects of sex, race, T1DM age of onset, and T1DM duration on the prevalence of an additional AID. RESULTS Mean ± SD age of T1DM onset was 21.2 ± 14.4 years. AID incidence and prevalence increased with age. Female sex strongly predicted AID risk. The most prevalent T1DM-associated AIDs were thyroid disease, collagen vascular diseases, and pernicious anemia. T1DM age of onset and T1DM duration predicted AID risk. Patients with late-onset T1DM after 30 years of age had higher risks of developing additional AIDs compared with patients with younger T1DM onset. CONCLUSIONS The prevalence of AIDs in patients with T1DM increases with age and female sex. Later onset of T1DM is an independent and significant risk factor for developing additional AIDs. Individuals who are diagnosed with T1DM at older ages, particularly women, should be monitored for other autoimmune conditions.

Objective: To determine the distribution of age of onset of T1DM in an adult cohort of patients with T1DM. Methods: T1DM patients from an adult academic diabetes center provided informed consent, completed a questionnaire and gave permission for medical record review. Demographics included age, gender and race. T1DM diagnosis was confirmed by history, occurrence of DKA, C-peptide and/or positive T1DM autoantibodies. Patients with diabetes due to pancreatic disease, chemotherapy, genetic syndromes or unclear etiology were not included. Results: Of the 1167 confirmed cases of T1DM, 563 (48.2%) were male and 604 (51.8%) were female; 107 (9.2%) were African-American and 1060 (90.8%) were Caucasian or other (30 years in 278 (23.8%). Males and females age at onset of T1DM ≥18 years were 53.1% and 48.3% respectively, NS (p=0.11). African-Americans and non-African-Americans diagnosed with T1DM at ≥18 years: 52.3% and 50.5% respectively, NS (p=0.71). In a subset of patients with current age ≥30 (n=971), the mean age of onset of T1DM was 23.2+/-14.8 years. Conclusion: In this cohort of adults with T1DM, over half of all patients were diagnosed at age ≥18 years, and 23.8% at age >30 years. This trend was consistent across race and gender and more pronounced in the subset with age ≥30 years. These findings challenge historical data that the mean age of onset of T1DM is in childhood. The strength of this dataset is accuracy of age of onset and diagnosis. The major limitation is that it is not population based. Because the reported age at onset of T1DM is highly dependent on the age of the cohort studied, epidemiologic studies of T1DM should include the entire age spectrum. Better awareness of T1DM in adults is needed to provide appropriate medical management and to ensure patient safety. Disclosure M. Salam: None. Y. Bao: None. C.J. Herrick: Stock/Shareholder; Spouse/Partner; Cardinal Health. J.B. McGill: Research Support; Self; AstraZeneca. Consultant; Self; Boehringer Ingelheim GmbH. Speaker's Bureau; Self; Aegerion Pharmaceuticals. Consultant; Self; Bayer AG, Dexcom, Inc., Intarcia Therapeutics, Inc.. Speaker's Bureau; Self; Janssen Pharmaceuticals, Inc., MannKind Corporation. Research Support; Self; Novartis Pharmaceuticals Corporation. Consultant; Self; Novo Nordisk A/S. J. Hughes: None.

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.

Objective Acquired clitoromegaly is rare and may result from hormonal and nonhormonal causes, and evaluation of the pregnant patient with clitoromegaly invokes a specific set of differential diagnoses. Methods Case report. Results We describe the case of a young woman with pregnancy-associated clitoral enlargement whose hormonal evaluation proved negative. Further investigation concluded that an epidermoid cyst was the culprit of her pseudoclitoromegaly. The patient underwent successful surgical resection and has had no recurrence at her subsequent pregnancy. Conclusion We review the differential diagnosis of clitoromegaly, including hormonal and nonhormonal causes, with focus on the evaluation of pregnancy-associated clitoromegaly.

Objective: Granulomatosis with polyangiitis (GPA), also known as Wegener's granulomatosis, is an autoimmune disease characterized by inflammation of blood vessels most often seen in the upper respiratory tract, lungs, kidneys, and skin. Central nervous system (CNS) involvement of GPA is rare, particularly in the pituitary, and can be difficult to treat.Methods: Case report.Results: We present a 30-year-old woman with pituitary and ocular GPA, whose unusually recalcitrant disease led to the development of pan-hypopituitarism and near-total vision loss. After failing multiple systemic immunosuppressants, she was ultimately treated with the novel immunomodulatory agent rituximab together with pulse corticosteroids, which achieved a gratifying response.Conclusion: Pituitary and optic chiasm involvement is a rare complication of GPA. We believe this case illustrates the complexity of management of pituitary GPA and provides insight into the potential utility of the biologic agent rituximab in this disease.

Context Moyamoya syndrome is an idiopathic brain vasculopathy characterized by stenosis of major intracranial arteries. It often presents in patients with type 1 diabetes or thyroid disease and may have an autoimmune etiology. Moyamoya-related stroke poses a diagnostic challenge as initial symptoms and deficits vary greatly from classic ischemic stroke to encephalopathy, psychiatric, or seizure disorder. Case description We report 4 patients with type 1 diabetes and other autoimmune diseases who developed moyamoya-related stroke at a young age. Despite having long-term diabetes, these patients exhibited no evidence of dyslipidemia or other typical risk factors for atherosclerosis which might contribute to premature stroke. Three of the four patients underwent revascularization surgery while one patient received conservative management. All patients had improved neurologic function after treatment, some with residual deficits. Conclusion We highlight the importance of recognizing moyamoya syndrome in patients with pre-existing autoimmune diseases such as type 1 diabetes, as prompt diagnosis and treatment can have major impact on patient outcome and quality of life.

Beta cells from nondiabetic mice transfer secretory vesicles to phagocytic cells. The passage was shown in culture studies where the transfer was probed with CD4 T cells reactive to insulin peptides. Two sets of vesicles were transferred, one containing insulin and another containing catabolites of insulin. The passage required live beta cells in a close cell contact interaction with the phagocytes. It was increased by high glucose concentration and required mobilization of intracellular Ca2+. Live images of beta cell-phagocyte interactions documented the intimacy of the membrane contact and the passage of the granules. The passage was found in beta cells isolated from islets of young nonobese diabetic (NOD) mice and nondiabetic mice as well as from nondiabetic humans. Ultrastructural analysis showed intraislet phagocytes containing vesicles having the distinct morphology of dense-core granules. These findings document a process whereby the contents of secretory granules become available to the immune system.

The convergence of multiple paracrine, juxtacrine, and intracellular signals is necessary to achieve proper glucagon secretion from the α-cells of the pancreatic islet. Elevated or dysregulated secretion of glucagon severely impairs the glycemic control of diabetic patients. Thus it is important to clarify how all these stimuli co-operate and interact to stimulate and or inhibit glucagon secretion. Using hyperspectral fluorescence microscopy, we measure the effect of glucagon modulators, insulin, somatostatin, and ephrins simultaneously on the activity of two second messengers, calcium and cyclic adenosine monophosphate (cAMP), in islet cells. We target genetically encoded biosensors to the cytoplasm, to the plasma membrane or to the nucleus. We hypothesize that in response to different stimuli, second messengers’ activities change differently in various cell compartments. Individual stimuli or their combination result in various patterns of activities, which we can use to improve our current mathematical model of glucose-inhibited glucagon secretion. These studies utilize both cell line models and primary cultured islet cells. This combination of specimens allows us to determine the conditions under which we can rely on cell lines to mimic intact islets hormone output. Having a reliable cell model for glucagon secretion form α-cells will be very beneficial for drug screening studies.

Type 1 diabetes is caused by autoimmune-mediated β cell destruction leading to insulin deficiency. The histone deacetylase SIRT1 plays an essential role in modulating several age-related diseases. Here we describe a family carrying a mutation in the SIRT1 gene, in which all five affected members developed an autoimmune disorder: four developed type 1 diabetes, and one developed ulcerative colitis. Initially, a 26-year-old man was diagnosed with the typical features of type 1 diabetes, including lean body mass, autoantibodies, T cell reactivity to β cell antigens, and a rapid dependence on insulin. Direct and exome sequencing identified the presence of a T-to-C exchange in exon 1 of SIRT1, corresponding to a leucine-to-proline mutation at residue 107. Expression of SIRT1-L107P in insulin-producing cells resulted in overproduction of nitric oxide, cytokines, and chemokines. These observations identify a role for SIRT1 in human autoimmunity and unveil a monogenic form of type 1 diabetes.