scholarly journals Human IAPP is a driver of painful diabetic peripheral neuropathy

2021 ◽  
Author(s):  
Mohammed M. H. Asiri ◽  
Sabine Versteeg ◽  
Elisabeth M. Brakkee ◽  
J. Henk Coert ◽  
C. Erik Hack ◽  
...  
Keyword(s):  
Peripheral Neuropathy ◽  
Sensory Neurons ◽  
Nerve Fibers ◽  
Elevated Plasma ◽  
Β Cells ◽  
Islet Amyloid ◽  
Painful Diabetic Peripheral Neuropathy ◽  
Intra Epidermal Nerve Fibers

AbstractPeripheral neuropathy is a frequent complication of type 2 diabetes mellitus (T2DM), of which the pathogenesis is not fully understood. We investigated whether human islet amyloid polypeptide (hIAPP), which forms pathogenic aggregates that damage islet β-cells in T2DM, is involved in T2DM-associated peripheral neuropathy. In vitro, hIAPP incubation with sensory neurons reduced neurite outgrowth. Transgenic hIAPP Ob/Ob mice, an established animal model for T2DM, as well as hIAPP mice, which have elevated plasma hIAPP levels but no hyperglycaemia. Both transgenic mice developed peripheral neuropathy as evidenced by pain-associated behavior and reduced intra-epidermal nerve fibers (IENF), suggesting hIAPP is a mediator of diabetic neuropathy. Intraplantar and intravenous hIAPP injection in WT mice induced long-lasting mechanical hypersensitivity and reduced IENF, whereas non-aggregating murine IAPP or mutated hIAPP (Pramlintide) did not have these effects, and were not toxic for cultured sensory neurons. In T2DM patients, significantly more hIAPP oligomers were found in the skin compared to non-T2DM controls. Thus, we provide evidence that hIAPP is toxic to sensory neurons, and mediates peripheral neuropathy in mice. The presence of hIAPP aggregates in skin of humans with T2DM supports the notion that human IAPP is a potential driver of T2DM neuropathy in man.

scholarly journals Amyloid damage to islet β-cells in type 2 diabetes: hypoxia or pseudo-hypoxia?

2019 ◽  
Author(s):  
Vittorio Bellotti ◽  
Alessandra Corazza ◽  
Beatrice Foglia ◽  
Erica Novo ◽  
J. Paul Simons ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Amyloid Deposition ◽  
Β Cells ◽  
Islet Amyloid ◽  
Good Tool ◽  
Amyloid Deposits ◽  
Oxygen Perfusion

ABSTRACTAggregation of islet amyloid polypeptide (IAPP) and amyloid deposition in the islets of Langerhans may significantly contribute to the multifactorial pathogenic mechanisms leading to type 2 diabetes. A direct toxic effect on β-cells of oligomeric IAAP has been demonstrated in in vitro models, but the mechanism operating in vivo is still unclear. Mice models presenting amyloid deposition and glucose intolerance represent a good tool for exploring in vivo a putative mechanism of toxicity directly related to the physical expansion of the extracellular matrix by the amyloid fibrillar aggregates. Based on our hypothesis that deposition of amyloid may influence the oxygen perfusion, we have calculated that the mean distribution of oxygen partial pressure would drop by more than 50 % in the presence of amyloid deposits in the islet. This condition of hypoxia caused by the remodelling of the extracellular space may explain the metabolic abnormalities in the Langerhans islets, otherwise interpreted as pseudo-hypoxic response to IAPP oligomers.

scholarly journals Nerve and Vascular Biomarkers in Skin Biopsies Differentiate Painful From Painless Peripheral Neuropathy in Type 2 Diabetes

2021 ◽  
Vol 2 ◽  
Author(s):  
Pallai Shillo ◽  
Yiangos Yiangou ◽  
Philippe Donatien ◽  
Marni Greig ◽  
Dinesh Selvarajah ◽  
...  
Keyword(s):  
Type 2 Diabetes ◽  
Peripheral Neuropathy ◽  
Blood Vessels ◽  
Diabetic Peripheral Neuropathy ◽  
Nerve Fibers ◽  
Pain Mechanisms ◽  
Painful Diabetic Peripheral Neuropathy ◽  
Skin Biopsies ◽  
Vascular Biomarkers

Painful diabetic peripheral neuropathy can be intractable with a major impact, yet the underlying pain mechanisms remain uncertain. A range of neuronal and vascular biomarkers was investigated in painful diabetic peripheral neuropathy (painful-DPN) and painless-DPN and used to differentiate painful-DPN from painless-DPN. Skin biopsies were collected from 61 patients with type 2 diabetes (T2D), and 19 healthy volunteers (HV). All subjects underwent detailed clinical and neurophysiological assessments. Based on the neuropathy composite score of the lower limbs [NIS(LL)] plus seven tests, the T2D subjects were subsequently divided into three groups: painful-DPN (n = 23), painless-DPN (n = 19), and No-DPN (n = 19). All subjects underwent punch skin biopsy, and immunohistochemistry used to quantify total intraepidermal nerve fibers (IENF) with protein gene product 9.5 (PGP9.5), regenerating nerve fibers with growth-associated protein 43 (GAP43), peptidergic nerve fibers with calcitonin gene-related peptide (CGRP), and blood vessels with von Willebrand Factor (vWF). The results showed that IENF density was severely decreased (p < 0.001) in both DPN groups, with no differences for PGP9.5, GAP43, CGRP, or GAP43/PGP9.5 ratios. There was a significant increase in blood vessel (vWF) density in painless-DPN and No-DPN groups compared to the HV group, but this was markedly greater in the painful-DPN group, and significantly higher than in the painless-DPN group (p < 0.0001). The ratio of sub-epidermal nerve fiber (SENF) density of CGRP:vWF showed a significant decrease in painful-DPN vs. painless-DPN (p = 0.014). In patients with T2D with advanced DPN, increased dermal vasculature and its ratio to nociceptors may differentiate painful-DPN from painless-DPN. We hypothesized that hypoxia-induced increase of blood vessels, which secrete algogenic substances including nerve growth factor (NGF), may expose their associated nociceptor fibers to a relative excess of algogens, thus leading to painful-DPN.

scholarly journals Pancreatic beta-cell granule peptides form heteromolecular complexes which inhibit islet amyloid polypeptide fibril formation

2004 ◽  
Vol 377 (3) ◽  
pp. 709-716 ◽  
Author(s):  
Emma T. A. S. JAIKARAN ◽  
Melanie R. NILSSON ◽  
Anne CLARK
Keyword(s):  
Type 2 Diabetes ◽  
Amyloid Fibrils ◽  
Secretory Granules ◽  
Pancreatic Beta Cell ◽  
Islet Amyloid Polypeptide ◽  
Fibril Formation ◽  
Islet Amyloid ◽  
Β Sheet

Islet amyloid polypeptide (IAPP), or ‘amylin’, is co-stored with insulin in secretory granules of pancreatic islet β-cells. In Type 2 diabetes, IAPP converts into a β-sheet conformation and oligomerizes to form amyloid fibrils and islet deposits. Granule components, including insulin, inhibit spontaneous IAPP fibril formation in vitro. To determine the mechanism of this inhibition, molecular interactions of insulin with human IAPP (hIAPP), rat IAPP (rIAPP) and other peptides were examined using surface plasmon resonance (BIAcore), CD and transmission electron microscopy (EM). hIAPP and rIAPP complexed with insulin, and this reaction was concentration-dependent. rIAPP and insulin, but not pro-insulin, bound to hIAPP. Insulin with a truncated B-chain, to prevent dimerization, also bound hIAPP. In the presence of insulin, hIAPP did not spontaneously develop β-sheet secondary structure or form fibrils. Insulin interacted with pre-formed IAPP fibrils in a regular repeating pattern, as demonstrated by immunoEM, suggesting that the binding sites for insulin remain exposed in hIAPP fibrils. Since rIAPP and hIAPP form complexes with insulin (and each other), this could explain the lack of amyloid fibrils in transgenic mice expressing hIAPP. It is likely that IAPP fibrillogenesis is inhibited in secretory granules (where the hIAPP concentration is in the millimolar range) by heteromolecular complex formation with insulin. Alterations in the proportions of insulin and IAPP in granules could disrupt the stability of the peptide. The increase in the proportion of unprocessed pro-insulin produced in Type 2 diabetes could be a major factor in destabilization of hIAPP and induction of fibril formation.

scholarly journals Teucrium polium: Potential Drug Source for Type 2 Diabetes Mellitus

Biology ◽  
2022 ◽  
Vol 11 (1) ◽  
pp. 128
Author(s):  
Yaser Albadr ◽  
Andrew Crowe ◽  
Rima Caccetta
Keyword(s):  
Diabetes Mellitus ◽  
Type 2 Diabetes ◽  
Type 2 Diabetes Mellitus ◽  
Insulin Secretion ◽  
Β Cells ◽  
Pancreatic Β Cells ◽  
Glucose Levels ◽  
Teucrium Polium

The prevalence of type 2 diabetes mellitus is rising globally and this disease is proposed to be the next pandemic after COVID-19. Although the cause of type 2 diabetes mellitus is unknown, it is believed to involve a complex array of genetic defects that affect metabolic pathways which eventually lead to hyperglycaemia. This hyperglycaemia arises from an inability of the insulin-sensitive cells to sufficiently respond to the secreted insulin, which eventually results in the inadequate secretion of insulin from pancreatic β-cells. Several treatments, utilising a variety of mechanisms, are available for type 2 diabetes mellitus. However, more medications are needed to assist with the optimal management of the different stages of the disease in patients of varying ages with the diverse combinations of other medications co-administered. Throughout modern history, some lead constituents from ancient medicinal plants have been investigated extensively and helped in developing synthetic antidiabetic drugs, such as metformin. Teucrium polium L. (Tp) is a herb that has a folk reputation for its antidiabetic potential. Previous studies indicate that Tp extracts significantly decrease blood glucose levels r and induce insulin secretion from pancreatic β-cells in vitro. Nonetheless, the constituent/s responsible for this action have not yet been elucidated. The effects appear to be, at least in part, attributable to the presence of selected flavonoids (apigenin, quercetin, and rutin). This review aims to examine the reported glucose-lowering effect of the herb, with a keen focus on insulin secretion, specifically related to type 2 diabetes mellitus. An analysis of the contribution of the key constituent flavonoids of Tp extracts will also be discussed.

scholarly journals Translational Control of Glucose-Induced Islet Amyloid Polypeptide Production in Pancreatic Islets

Endocrinology ◽  
2012 ◽  
Vol 153 (5) ◽  
pp. 2082-2087 ◽  
Author(s):  
Cristina Alarcon ◽  
C. Bruce Verchere ◽  
Christopher J. Rhodes
Keyword(s):  
Translational Control ◽  
Islet Amyloid Polypeptide ◽  
Glucose Regulation ◽  
Mrna Levels ◽  
Β Cells ◽  
Islet Amyloid ◽  
Isolated Rat Islets ◽  
Proprotein Processing ◽  
Isolated Rat

Dysfunctional islet amyloid polypeptide (IAPP) biosynthesis and/or processing are thought contribute to formation of islet amyloid in type 2 diabetes. However, it is unclear how normal pro-IAPP biosynthesis and processing are regulated to be able to define such dysfunction. Here, it was found that acute exposure to high glucose concentrations coordinately regulated the biosynthesis of pro-IAPP, proinsulin, and its proprotein convertase PC1/3 in normal isolated rat islets, without affecting their respective mRNA levels. Pro-7B2 biosynthesis, like that of pro-PC2, did not appreciably change, but this was likely due to a much higher expression in pancreatic α-cells masking glucose regulation of their biosynthesis in β-cells. Biosynthesis of pro-SAAS, the putative PC1/3 chaperone, was unaffected by glucose, consistent with its scarce expression in β-cells. We conclude that translational control of pro-IAPP biosynthesis, in parallel to the pro-PC1/3, pro-PC2, and pro-7B2 proprotein-processing endopeptidases/chaperones, is the predominate mechanism to produce IAPP in islet β-cells.

scholarly journals Dynamics of β-cell turnover: evidence for β-cell turnover and regeneration from sources of β-cells other than β-cell replication in the HIP rat

2009 ◽  
Vol 297 (2) ◽  
pp. E323-E330 ◽  
Author(s):  
Erica Manesso ◽  
Gianna M. Toffolo ◽  
Yoshifumi Saisho ◽  
Alexandra E. Butler ◽  
Aleksey V. Matveyenko ◽  
...  
Keyword(s):  
Cell Mass ◽  
Cell Formation ◽  
Cell Regeneration ◽  
Cell Turnover ◽  
Cell Replication ◽  
Wild Type ◽  
Β Cells ◽  
Β Cell ◽  
Islet Amyloid

Type 2 diabetes is characterized by hyperglycemia, a deficit in β-cells, increased β-cell apoptosis, and islet amyloid derived from islet amyloid polypeptide (IAPP). These characteristics are recapitulated in the human IAPP transgenic (HIP) rat. We developed a mathematical model to quantify β-cell turnover and applied it to nondiabetic wild type (WT) vs. HIP rats from age 2 days to 10 mo to establish 1) whether β-cell formation is derived exclusively from β-cell replication, or whether other sources of β-cells (OSB) are present, and 2) to what extent, if any, there is attempted β-cell regeneration in the HIP rat and if this is through β-cell replication or OSB. We conclude that formation and maintenance of adult β-cells depends largely (∼80%) on formation of β-cells independent from β-cell duplication. Moreover, this source adaptively increases in the HIP rat, implying attempted β-cell regeneration that substantially slows loss of β-cell mass.

scholarly journals Transcriptomic Analysis of Human Sensory Neurons in Painful Diabetic Neuropathy Reveals Inflammation and Neuronal Loss

2021 ◽  
Author(s):  
Bradford Hall ◽  
Emma Macdonald ◽  
Margaret Cassidy ◽  
Sijung Yun ◽  
Matthew Sapio ◽  
...  
Keyword(s):  
Neuropathic Pain ◽  
Sensory Neurons ◽  
Molecular Mechanisms ◽  
Neuronal Loss ◽  
Gene Profile ◽  
Painful Neuropathy ◽  
Painful Diabetic Peripheral Neuropathy ◽  
Neuronal Genes ◽  
Transcriptome Analyses

Pathological sensations caused by peripheral painful neuropathy occurring in Type 2 diabetes mellitus (T2DM) are often described as sharp and burning and are commonly spontaneous in origin. Proposed etiologies implicate dysfunction of nociceptive sensory neurons in dorsal root ganglia (DRG) induced by generation of reactive oxygen species, microvascular defects, and ongoing axonal degeneration and regeneration. To investigate the molecular mechanisms contributing to diabetic pain, DRGs were acquired postmortem from patients who had been experiencing painful diabetic peripheral neuropathy (DPN) and subjected to transcriptome analyses to identify genes contributing to pathological processes and neuropathic pain. DPN occurs in distal extremities resulting in the characteristic glove and stocking pattern. Accordingly, the L4 and L5 DRGs, which contain the perikarya of primary afferent neurons innervating the foot, were analyzed from five DPN patients and compared with seven controls. Transcriptome analyses identified 844 differentially expressed genes. We observed increases in levels of inflammation-associated genes from macrophages in DPN patients that may contribute to increased pain hypersensitivity and, conversely, there were frequent decreases in neuronally-related genes. The elevated inflammatory gene profile and the accompanying downregulation of multiple neuronal genes provide new insights into intraganglionic pathology and mechanisms causing neuropathic pain in DPN patients with T2DM.

scholarly journals Tissue factor and Toll-like receptor (TLR)4 in hyperglycaemia-hyperinsulinaemia

2015 ◽  
Vol 113 (04) ◽  
pp. 750-758 ◽  
Author(s):  
Anamika Singh ◽  
Guenther Boden ◽  
A. Koneti Rao
Keyword(s):  
Tissue Factor ◽  
Healthy Subjects ◽  
Toll Like Receptor ◽  
Elevated Plasma ◽  
Type 2 Dm ◽  
Type 1 Dm

SummaryDiabetes mellitus (DM) patients have an increased incidence of cardiovascular events. Blood tissue factor-procoagulant activity (TF-PCA), the initiating mechanism for blood coagulation, is elevated in DM. We have shown that hyperglycaemia (HG), hyperinsulinaemia (HI) and combined HG+HI (induced using 24-hour infusion clamps) increases TF-PCA in healthy and type 2 DM (T2DM) subjects, but not in type 1 DM (T1DM) subjects. The mechanisms for this are unknown. DM patients have elevated plasma lipopolysaccharide (LPS), a toll-like receptor (TLR) 4 ligand. We postulated that TLR4 plays a role in modulating TF levels. We studied the effect of HG+HI on TLR4 and TF-PCA in vivo during 24-hour HG+HI infusion clamps in healthy subjects, and T1DM and T2DM subjects, and in vitro in blood. In vivo, in healthy subjects, 24-hour HG + HI infusion increased TLR4 six-fold, which correlated with TF-PCA (r=0.91, p<0.0001). T2DM patients showed smaller increases in both. In T1DM subjects, TLR4 declined (50%, p<0.05) and correlated with TF-PCA (r=0.55; p<0.05). In vitro, HG (200 mg/dl added glucose) and HI (1-100 nM added insulin) increased TF-PCA in healthy subjects (˜2-fold, 2-4 hours). Insulin inhibited by ~30% LPSinduced increase in TF-PCA and high glucose reversed it. TLR4 levels paralleled TF-PCA (r=0.71, p<0.0001); HG and HI increased TLR4 and insulin inhibited LPS-induced TLR4 increase. This is first evidence that even in healthy subjects, HG of short duration increases TLR4 and TFPCA, key players in inflammation and thrombosis. TLR4-TF interplay is strikingly different in non-diabetic, T1DM and T2DM subjects.

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