There is a fundamental gap in understanding how the islets of Langerhans function in vivo, either in the native environment in the pancreas or after transplantation to treat type 1 diabetes. Most studies on islet function have been performed in vitro, and as a consequence little is known about the role of innervation on islet hormone secretion. The long-term goal of our research is to understand the cell biology of islets of Langerhans in the living organism. The objective of this particular application is to determine the role innervation plays in the secretion of islet hormones using a new technological platform allowing in vivo imaging of vascularized and reinnervated islets after transplantation. In this new technology, islets are transplanted into the anterior chamber of the eye, and their function is recorded locally and systemically after manipulation of the eye's neural input. The central hypothesis is that the autonomic nervous system modulates human islet function by regulating blood flow within the islet. In contrast to mouse islets, human endocrine cells are not affected directly by the autonomic innervation. In the proposed mechanism, autonomic nerve fibers strongly innervate contractile pericytes that work as sphincters to change blood flow locally, thus changing the efficiency of glucose sensing and of hormone release into the circulation. The rationale for the proposed research is that the results will contribute a missing, fundamental element to basic knowledge, without which the biology of human islets cannot be understood. The proposed research is therefore relevant to the mission of the NIH that pertains to the pursuit of fundamental knowledge about the nature and behavior of living systems. Guided by strong preliminary data, this hypothesis will be tested by pursuing three specific aims: 1) Species differences in the innervation patterns of pancreatic islets in vitro;2) Intraocular islet grafts determine their own innervation pattern;and 3) The role of neural input on glucose homeostasis in vivo. Under the first aim, the innervation patterns of islets and the neurotransmitter receptor profiles of the innervated endocrine cell types will be systematically examined in mouse and human islets using immunohistochemistry and imaging of intracellular [Ca2+]. Under the second aim, intraocular human and mouse islet grafts will be compared in terms of immunohistochemical staining patterns and in vivo tracing of autonomic nervous fibers. Under the third aim, local islet cell responses and regulation of glucose homeostasis by mouse and human islet grafts will be challenged by activating the parasympathetic and sympathetic components of the pupillary reflex, by pharmacological blockade, and by selective elimination of the neural input. The proposed work is innovative because it capitalizes on a new technological platform that allows for the first time in vivo imaging the function of innervated human and mouse islet. The proposed research is significant because it is expected to advance and expand current models of the regulation of glucose homeostasis by pancreatic islets.

Public Health Relevance

The proposed work will demonstrate the role of innervation for human islet cell function. It capitalizes on a new technological platform developed by our group allowing for the first time in vivo imaging of innervated human and mouse islets. As a major expected outcome we will obtain a comprehensive picture of islet innervation, which will have a strong impact on current models of islet regulation of glucose homeostasis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK084321-02
Application #
8228052
Study Section
Cellular Aspects of Diabetes and Obesity Study Section (CADO)
Program Officer
Appel, Michael C
Project Start
2011-02-15
Project End
2016-01-31
Budget Start
2012-02-01
Budget End
2013-01-31
Support Year
2
Fiscal Year
2012
Total Cost
$342,720
Indirect Cost
$118,720
Name
University of Miami School of Medicine
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
052780918
City
Coral Gables
State
FL
Country
United States
Zip Code
33146
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Kistler, Andreas D; Caicedo, Alejandro; Abdulreda, Midhat H et al. (2014) In vivo imaging of kidney glomeruli transplanted into the anterior chamber of the mouse eye. Sci Rep 4:3872
Rodriguez-Diaz, Rayner; Caicedo, Alejandro (2014) Neural control of the endocrine pancreas. Best Pract Res Clin Endocrinol Metab 28:745-56
Faleo, Gaetano; Berggren, Per-Olof; Pileggi, Antonello (2014) Intravital imaging of cytotoxic T lymphocytes. Methods Mol Biol 1186:121-9
Molina, Judith; Rodriguez-Diaz, Rayner; Fachado, Alberto et al. (2014) Control of insulin secretion by cholinergic signaling in the human pancreatic islet. Diabetes 63:2714-26
AlmaƧa, Joana; Molina, Judith; Arrojo E Drigo, Rafael et al. (2014) Young capillary vessels rejuvenate aged pancreatic islets. Proc Natl Acad Sci U S A 111:17612-7
Rodriguez-Diaz, Rayner; Menegaz, Danusa; Caicedo, Alejandro (2014) Neurotransmitters act as paracrine signals to regulate insulin secretion from the human pancreatic islet. J Physiol 592:3413-7
Rodriguez-Diaz, Rayner; Caicedo, Alejandro (2013) Novel approaches to studying the role of innervation in the biology of pancreatic islets. Endocrinol Metab Clin North Am 42:39-56
Caicedo, Alejandro (2013) Paracrine and autocrine interactions in the human islet: more than meets the eye. Semin Cell Dev Biol 24:11-21
Rodriguez-Diaz, Rayner; Abdulreda, Midhat H; Formoso, Alexander L et al. (2011) Innervation patterns of autonomic axons in the human endocrine pancreas. Cell Metab 14:45-54

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