AG Pädiatrische Diabetologie der DDG
16:05 Uhr
Immunologie des Typ-1-Diabets: Was man heute weiß
16:25 Uhr
Impfungen und Typ-1-Diabetes: Trigger oder Schutz?
16:45 Uhr
Screening auf Typ-1-Diabets: Die Grundlage für eine frühzeitige Intervention
17:05 Uhr
FV 20:
Reduced hepatocellular lipid content before diabetes manifestation in a model of accelerated type 1 diabetes
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Autor:innen:
C. Wessel (Düsseldorf, DE)
M. Rothe (Düsseldorf, DE)
J. Hwang (Düsseldorf, DE)
M. Roden (Düsseldorf, DE)
V. Burkart (Düsseldorf, DE)
Background/Aims: Toll-like-receptor 4-deficient (TLR4-/-) non-obese diabetic (NOD) mice exhibit accelerated development of autoimmune insulin-deficient diabetes, which is accompanied by impaired glucose- and lipid metabolism before the age of diabetes manifestation. As hepatic lipid metabolism plays a central role in the regulation of whole-body energy homeostasis, we hypothesized, that accelerated diabetes development in NOD-TLR4-/- mice associates with impaired lipid homeostasis in the liver before diabetes onset.
Methods: Hepatocellular lipid (HCL) contents were determined by 1H magnetic resonance (MR) spectroscopy in female normoglycemic TLR4-expressing (NOD-TLR4+/+) and TLR4-deficient (NOD-TLR4-/-) NOD-mice (age: 70-90 days). Liver volume was quantified by MR imaging. Free fatty acid (FFA) concentrations in plasma were determined photometrically. During an intraperitoneal glucose tolerance test (ipGTT), plasma insulin concentrations were detected by ELISA. Expression of fatty acid receptors (CD36, FFAR2) was analyzed in liver tissue by western-blotting.
Results: Compared to NOD-TLR4+/+, NOD-TLR4-/- mice had higher plasma FFA concentrations (0.52±0.05 vs. 0.75±0.04 mmol/l; p < 0.01), but 43% lower insulin concentrations 15 minutes after ipGTT initiation (p < 0.05). NOD-TLR4-/- and NOD-TLR4+/+ mice showed comparable liver weight (1.14±0.03 vs. 1.15±0.03 g) and volume (1.02±0.05 vs. 1.11±0.04 ml). However, NOD-TLR4-/- mice showed lower HCL contents than NOD-TLR4+/+ mice (2.4±0.3 vs. 4.2±0.7%; p < 0.05). CD36 and FFAR2 in liver showed similar expression levels in NOD-TLR4-/- (2.27±0.30; 0.45±0.10 relative expression) and NOD-TLR4+/+ mice (2.17±0.52; 0.42±0.09 relative expression).
Conclusion: The reduction of HCL content preceding the manifestation of accelerated insulin-deficient diabetes in NOD-TLR4-/- mice could result from lower rates of insulin-mediated triglyceride synthesis or increased lipolysis.
17:15 Uhr
FV 21:
Parallel multi-parametric monitoring of single pancreatic islets in a microfluidic Organ-on-Chip system made from glass.
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Autor:innen:
T. Schulze (Braunschweig, DE)
K. Mattern (Braunschweig, DE)
A. Dietzel (Braunschweig, DE)
I. Rustenbeck (Braunschweig, DE)
Background and aims: Obtaining reproducible and reliable data from small amounts of tissue is still a major problem in basic and preclinical research on pancreatic islets. Here, we demonstrate an islet-on-chip system made from glass for parallel multi-parametric measurements of single pancreatic islets to overcome this challenge.
Materials and Methods: The chip was made from glass by femtosecond laser ablation and subsequent surface smoothing. The flow dynamics were characterized by simulation and by measuring washout-kinetics of fluorescent dyes. NAD(P)H-, FAD- autofluorescence and Cal 630 fluorescence (cytosolic Ca2+ concentration = [Ca2+]i) of NMRI mouse islets were simultaneously measured in five independent experiments by live cell imaging. Insulin content of fractionated efflux was measured by ultrasensitive ELISA.
Results: The islet-on-chip system had the size of a microscope slide and contained five independent parallel channels, each with a well of 500 µm depth to hold a single islet. An aperture above the well permitted loading and unloading of the islet. Fluorescence washout-kinetics confirmed the uniformity of channels and wells. Islets were well retained at perfusion velocities of 40 µl/min and responded to 25 mM glucose with increased insulin secretion, increased levels of NAD(P)H and FADH2 and an oscillatory pattern of [Ca2+]i. 40 mM KCl markedly increased insulin secretion and [Ca2+]i, but caused only a minor increase of NAD(P)H and FADH2.
Conclusion: The present microfluidic islet-on-chip system with a parallel independent channel design permits robust multi-parametric characterization of individual islet function. Thus, throughput, precision and coherence are increased as compared to conventional perifusion systems.