K Laubner

Human Krüppel-like factor 11 inhibits human proinsulin promoter activity in pancreatic beta cells.

Aims/hypothesisThe Krüppel-like factor 11 (KLF11; TIEG2), a pancreas-enriched Sp1-like transcription factor, is a known negative regulator of pancreatic exocrine cell growth. A recent study indicated KLF11-induced activation of the human proinsulin promoter (hInsP).Materials and methodsWe investigated the functional role of KLF11 in pancreatic beta cells.ResultsEndogenous KLF11 mRNA expression was found in whole rat pancreas, human pancreatic islets and INS-1E beta cells and was profoundly reduced by high glucose in INS-1E. Cotransfections of INS-1E and beta-TC3 beta cells with a human (h)KLF11 expression plasmid and an hInsP-driven reporter plasmid resulted in a substantial dose-dependent and glucose-independent inhibition of proinsulin promoter activity. 5′-deletion of hInsP demonstrated that hKLF11 acts via DNA sequences upstream of −173 and requires the beta cell-specific transcription machinery, since hKLF11-mediated inhibition of promoter activity was abolished in HEK293 cells. Besides a previously described GC box, we further identified a CACCC box within the hInsP, both putative KLF11-binding motifs. Electrophoretic mobility shift analysis (EMSA) verified binding of in vitro translated hKLF11 to the GC box, but neither hKLF11-induced inhibition nor basal hInsP activity was altered by mutation or 5′-deletion of the GC box. In contrast, CACCC box mutation substantially reduced basal promoter activity and partially diminished hKLF11 inhibition, although binding of in vitro translated hKLF11 to the CACCC box could not be verified by EMSA.Conclusions/interpretationIn rodent beta cell lines, we demonstrate hKLF11-overexpression of human proinsulin gene expression and characterise a prominent role for the CACCC box in maintaining basal proinsulin promoter activity.

Protein Phosphatase 1 (PP-1)-Dependent Inhibition of Insulin Secretion by Leptin in INS-1 Pancreatic β-Cells and Human Pancreatic Islets

Leptin inhibits insulin secretion from pancreatic β-cells, and in turn, insulin stimulates leptin biosynthesis and secretion from adipose tissue. Dysfunction of this adipoinsular feedback loop has been proposed to be involved in the development of hyperinsulinemia and type 2 diabetes mellitus. At the molecular level, leptin acts through various pathways, which in combination confer inhibitory effects on insulin biosynthesis and secretion. The aim of this study was to identify molecular mechanisms of leptin action on insulin secretion in pancreatic β-cells. To identify novel leptin-regulated genes, we performed subtraction PCR in INS-1 β-cells. Regulated expression of identified genes was confirmed by RT-PCR and Northern and Western blotting. Furthermore, functional impact on β-cell function was characterized by insulin-secretion assays, intracellular Ca²(+) concentration measurements, and enzyme activity assays. PP-1α, the catalytic subunit of protein phosphatase 1 (PP-1), was identified as a novel gene down-regulated by leptin in INS-1 pancreatic β-cells. Expression of PP-1α was verified in human pancreatic sections. PP-1α mRNA and protein expression is down-regulated by leptin, which culminates in reduction of PP-1 enzyme activity in β-cells. In addition, glucose-induced insulin secretion was inhibited by nuclear inhibitor of PP-1 and calyculin A, which was in part mediated by a reduction of PP-1-dependent calcium influx into INS-1 β-cells. These results identify a novel molecular pathway by which leptin confers inhibitory action on insulin secretion, and impaired PP-1 inhibition by leptin may be involved in dysfunction of the adipoinsular axis during the development of hyperinsulinemia and type 2 diabetes mellitus.

Adherence to clinical care guidelines for cystic fibrosis-related diabetes in 659 German/Austrian patients

BACKGROUND In Germany/Austria, data on medical care for cystic fibrosis-related diabetes (CFRD) is limited. METHODS Anonymized data from 659 CFRD patients were analyzed and compared to the latest ADA/CFF guidelines. RESULTS Specialized diabetes clinics were attended less frequently than recommended (3.1 vs. 4.0 times yearly). 7.9% of patients had a complete profile of examinations: diabetes education (44.9%), HbA1c (88.8%), blood pressure (79.5%), BMI (86.5%), lipid status (37.5%), retinopathy (29.9%), microalbuminuria (33.2%), and self-monitoring of blood glucose (71.6%). HbA1c and blood pressure were measured less frequently than recommended (2.3 and 2.0 vs. 4.0 times yearly). Overall, guidelines were followed more frequently in children than adults. Contrary to recommendations, not all patients were treated with insulin (77.2 vs. 100.0%). Insulin therapy was initiated earlier in children than adults, but there was still a substantial delay (0.9 vs. 2.7years after diagnosis, p<0.001). CONCLUSION In CFRD patients studied, adherence to care guidelines was suboptimal.

Why is insulin pump treatment rarely used in adolescents and young adults with cystic fibrosis-related diabetes?

In type 1 diabetes (T1D), the use of continuous subcutaneous insulin infusion (CSII) has increased steadily in the last years. Compared with conventional insulin injection regimes, major advantages might be a nearly physiological insulin secretion, lower rates of hypoglycemia, higher flexibility in daily life, and increased quality of life. Data on CSII in cystic fibrosis‐related diabetes (CFRD) are scarce.

Human Krüppel-like factor 11 differentially regulates human insulin promoter activity in β-cells and non-β-cells via p300 and PDX1 through the regulatory sites A3 and CACCC box.

Human Krüppel-like factor 11 (hKLF11) has been characterised to both activate and inhibit human insulin promoter (hInsP) activity. Since KLF11 is capable to differentially regulate genes dependent on recruited cofactors, we investigated the effects of hKLF11 on cotransfected hInsP in both β-cells and non-β-cells. hKLF11 protein interacts with hp300 but not with hPDX1. Overexpressed hKLF11 stimulates PDX1-transactivation of hInsP in HEK293 non-β-cells, but confers inhibition in INS-1E β-cells. Both hKLF11 functions can be neutralised by the p300 inhibitor E1A, increased hp300 levels (INS-1E), dominant negative (DN)-PDX1 and by mutation of the PDX1 binding site A3 or the CACCC box. In summary, hKLF11 differentially regulates hInsP activity depending on the molecular context via modulation of p300:PDX1 interactions with the A3 element and CACCC box. We postulate that KLF11 has a role in fine-tuning insulin transcription in certain cellular situations rather than representing a major transcriptional activator or repressor of the insulin gene.

Longitudinal evaluation of efficacy, safety and nutritional status during one-year treatment with the duodenal-jejunal bypass liner

BACKGROUND The endoscopic duodenal-jejunal bypass liner (DJBL) represents a novel temporary endoscopic approach for treatment of obesity-associated type 2 diabetes. Recent results from the German DJBL registry confirmed substantial positive metabolic effects of the DJBL in type 2 diabetes. However, the last Food and Drug Administration trial was stopped due to a high occurrence of hepatic abscesses (3.5%). OBJECTIVES Here, we analyzed time courses of development of co-morbidities, nutritive changes, and occurrence of adverse events during the 1-year treatment phase with the DJBL in the German DJBL registry. METHODS Sixty-six patients from the registry were analyzed for efficacy, safety, and nutritional status. Patient data sets were analyzed at implantation, 3 and 6 months after implantation, and at explantation visits. RESULTS Weight, body mass index, glycated hemoglobin, and low-density lipoprotein cholesterol primarily declined during the first 3 months after implantation, whereas systolic and diastolic blood pressure were predominantly reduced during the second half of the treatment phase. Severe DJBL-associated side effects were mainly documented at the explantation visit (intestinal obstruction [1.7%], dislocation [1.7%], and liver abscess [1.7%]). Measurements of serum concentrations of ferritin, albumin, vitamin B12, folic acid, 25-hydroxyvitamin D3 (25 OH-Vit-D3), and calcium provided suggestive evidence of a possible decrease of nutritional absorption of vitamins and trace elements by the DJBL. CONCLUSIONS The DJBL demonstrates high efficacy with substantial improvement of all parameters of the metabolic syndrome and the potential for reduction of comedications in overweight patients with type 2 diabetes. These registry results are important to optimize recommendations for adaptation of concomitant medication, surveillance of adverse events, nutritional status and supplementation, and adaptation of the implantation period of the DJBL.

17q12 Deletion Syndrome as a rare cause for diabetes mellitus type MODY.

Context Maturity-onset diabetes of the young type 5 (MODY5) is caused by mutations of the hepatocyte nuclear factor 1 homeobox β gene (HNF1B). Although clinical characteristics and therapeutic management of MODY5 are increasingly better defined, adequate consideration of the frequent association of MODY5 with 17q12 deletion syndrome is often missing. Evidence Acquisition We report two cases of patients with 17q12 deletion syndrome who presented to our clinic. Furthermore, we reviewed the existing literature to improve systematic diagnostic and therapeutic approaches. A PubMed search using the terms 17q12 deletion syndrome, diabetes mellitus type MODY5, and/or HNF1B was performed. Evidence Synthesis Three hundred sixty-one cases of postnatal 17q12 deletion syndrome were assessed, and details on clinical manifestations, diagnostic approaches, and therapeutic management were reviewed and compared with the two cases at our clinic. Furthermore, data on pathogenic mechanisms and their clinical implications were evaluated. Conclusion The 17q12 deletion syndrome usually comprises MODY5, structural or functional abnormalities of the kidneys, and neurodevelopmental or neuropsychiatric disorders. A complete deletion of HNF1B can be found in about 50% of patients with MODY5. A wide variety of additional clinical features, including genital and brain malformations, has been reported. Because HNF1B deletions are virtually always part of a 17q12 deletion syndrome and common genetic analyses for evaluation of MODY5 are unable to detect the deletion of a 1.4-Mb chromosomal region, initial attention to the syndromal features at the stage of diagnosis is of considerable importance for establishing correct diagnosis, subsequent therapy, and interdisciplinary patient care.

Mesenchymal stem cell (MSC)-mediated survival of insulin producing pancreatic β-cells during cellular stress involves signalling via Akt and ERK1/2

Mesenchymal stem cells (MSC) are of interest for cell therapy since their secreted factors mediate immunomodulation and support tissue regeneration. This study investigated the direct humoral interactions between MSC and pancreatic β-cells using human telomerase-immortalized MSC (hMSC-TERT) and rat insulinoma-derived INS-1E β-cells. hMSC-TERT supported survival of cocultured INS-1E β-cells during cellular stress by alloxan (ALX) and streptozotocin (STZ), but not in response to IL-1β. Accordingly, hMSC-TERT had no effect on inflammatory cytokine-related signalling via NF-kB and p-JNK but maintained p-Akt and upregulated p-ERK1/2. Inhibition of either p-Akt or p-ERK1/2 did not abolish protection by hMSC-TERT but activated the respective non-inhibited pathway. This suggests that one pathway compensates for the other. Main results were confirmed in mouse islets except hMSC-TERT-mediated upregulation of p-ERK1/2. Therefore, MSC promote β-cell survival by preservation of p-Akt signalling and further involve p-ERK1/2 activation in certain conditions such as loss of p-Akt or insulinoma background.

Comparative efficacy and safety of the duodenal-jejunal bypass liner in obese patients with type 2 diabetes mellitus: A case control study

The duodenal‐jejunal bypass liner (DJBL) is an endoscopic device mimicking surgical duodenal‐jejunal bypass, and is indicated for the treatment of obesity‐associated type 2 diabetes mellitus. This analysis was conducted to evaluate the efficacy and safety of the DJBL in comparison to lifestyle changes and antidiabetic drugs.

Ischemic Duodenal Ulceration after Transarterial Chemoembolization for Hepatocellular Carcinoma: A Case Report

Drug-eluting bead transarterial chemoembolization (DEB-TACE) is a well-established, minimally invasive interventional treatment for nonresectable hepatocellular carcinoma (HCC). Generally, TACE is regarded as safe and effective with a low complication rate. However, remote gastrointestinal ischemia due to the carryover of embolic material into visceral arteries is a rare but serious complication of TACE. In this report, we present a case of duodenal ulceration with contained perforation and severe necrotizing pancreatitis after TACE in a patient with nonresectable HCC and underlying hepatitis C virus associated with Child-Pugh stage B liver cirrhosis. This patient showed, for the first time, complete endoscopic and clinical recovery within 2 months of conservative treatment. Considering the high mortality rate from surgical intervention in all previously reported patients, the significant recovery potential demonstrated by our case suggests conservative treatment with antibiotics and parenteral nutrition combined with close clinical, radiological, and endoscopic monitoring should be considered in all clinically stable patients without signs of peritonism or septic sequelae.