Geological Field Trips

This field trip guide organized in the framework of the Goldschmidt Conference 2013, held in Florence from August 25 to 30, 2013, is here presented. The two-days field trip, shows some of the many geological, naturalistic and cultural features in the Fiorano area (Modena), in which history, geology and passion for Ferrari come together in a perfect marriage. The first excursion day is dedicated to visit the Natural Reserve of Salse di Nirano, where the mud volcanoes, produced by the cold mud, salt water and hydrocarbons - mainly methane- can be observed. The second day is devoted to visit the Ferrari Museum and goes on at the Spezzano Castle, hosting the Ceramics Museum. Clays are, in fact, abundant in the hilly margin, where they form badlands, characteristic narrow crests washed out by running waters. In the Castle there is also a Balsamic Vinegar producing Consortium, it’s a peculiar and typical product of Modena province. The itinerary ends with the tour to Enzo Ferrari’s Birthplace at Modena

The Role of Dipeptidyl Peptidase – 4 Inhibitors in Diabetic Kidney Disease

Despite major advances in the understanding of the molecular mechanisms that underpin the development of diabetic kidney disease, current best practice still leaves a significant proportion of patients with end stage kidney disease requiring renal replacement therapy. This is on a background of an increasing diabetes epidemic worldwide. Although kidney failure is a major cause of morbidity the main cause of death remains cardiovascular in nature. Hence diabetic therapies which are both cardio-renal protective seem the logical way forward. In this review we discuss the dipeptidyl peptidase 4 inhibitors which are glucose lowering agents used clinically and their role in diabetic kidney disease with specific focus on renoprotection and surrogate markers of cardiovascular disease. We highlight the novel pleiotropic effects of dipeptidyl peptidase 4 that make it an attractive additional target to combat the fibrotic and inflammatory pathways in diabetic kidney disease and also discuss the current literature on the cardiovascular safety profile of dipeptidyl peptidase 4 inhibitors. Clearly these observed renoprotective effects will need to be confirmed by clinical trials to determine whether they translate into beneficial effects to patients with diabetes

Role of Toll-like receptors in diabetic nephropathy

Abstract Diabetic nephropathy is the leading cause of kidney failure and its increasing prevalence and incidence has imposed global socio-economic stress on healthcare systems worldwide. Although historically considered a metabolic disorder, recent studies have established that inflammatory responses are central to the pathogenesis of diabetic nephropathy. TLRs (Toll-like receptors) are a family of pattern recognition receptors responsible for the initiation of inflammatory and immune responses. The regulation of TLR2 and TLR4 have been implicated in the pathogenesis of various kidney diseases, and emerging evidence shows their involvement in the perpetuation of inflammation in the diabetic kidney. The present review focuses on the relative contributions of TLR2 and TLR4 in recognizing endogenous ligands relevant to diabetic nephropathy and their subsequent activation of NF-κB (nuclear factor κB), which results in the synthesis and secretion of pro-inflammatory cytokines and chemokines. Moreover, we discuss the pro-inflammatory signalling pathways of TLR2 and TLR4, in which their interruption or blockade may prove to be important therapeutic targets, potentially translated into clinical treatments for diabetic nephropathy. Currently, inhibitors to TLR2 and TLR4 are undergoing clinical trials in various inflammatory models of disease, but none in patients with diabetic nephropathy. Given the existing literature, there is a fundamental necessity to undertake trials in patients with diabetic nephropathy with a focus on renal end points

The Dipeptidyl Peptidase-4 Inhibitor Linagliptin Preserves Endothelial Function in Mesenteric Arteries from Type 1 Diabetic Rats without Decreasing Plasma Glucose.

The aim of the study was to investigate the effect of the DPP-4 inhibitor linagliptin on the mechanism(s) of endothelium-dependent relaxation in mesenteric arteries from STZ-induced diabetic rats. Both normal and diabetic animals received linagliptin (2 mg/kg) daily by oral gavage for a period of 4 weeks. To measure superoxide generation in mesenteric arteries, lucigenin-enhanced chemiluminescence was used. ACh-induced relaxation of mesenteric arteries was assessed using organ bath techniques and Western blotting was used to investigate protein expression. Pharmacological tools (1 μM TRAM-34, 1 μM apamin, 100 nM Ibtx, 100 μM L-NNA, 10 μM ODQ) were used to distinguish between NO and EDH-mediated relaxation. Linagliptin did not affect plasma glucose, but did decrease vascular superoxide levels. Diabetes reduced responses to ACh but did not affect endothelium-independent responses to SNP. Linagliptin improved endothelial function indicated by a significant increase in responses to ACh. Diabetes impaired the contribution of both nitric oxide (NO) and endothelium-dependent hyperpolarization (EDH) to endothelium-dependent relaxation and linagliptin treatment significantly enhanced the contribution of both relaxing factors. Western blotting demonstrated that diabetes also increased expression of Nox2 and decreased expression and dimerization of endothelial NO synthase, effects that were reversed by linagliptin. These findings demonstrate treatment of type 1 diabetic rats with linagliptin significantly reduced vascular superoxide levels and preserved both NO and EDH-mediated relaxation indicating that linagliptin can improve endothelial function in diabetes independently of any glucose lowering activity

Linagliptin Limits High Glucose Induced Conversion of Latent to Active TGFß through Interaction with CIM6PR and Limits Renal Tubulointerstitial Fibronectin.

In addition to lowering blood glucose in patients with type 2 diabetes mellitus, dipeptidyl peptidase 4 (DPP4) inhibitors have been shown to be antifibrotic. We have previously shown that cation independent mannose-6-phosphate receptor (CIM6PR) facilitates the conversion of latent to active transforming growth factor β1 (GFß1) in renal proximal tubular cells (PTCs) and linagliptin (a DPP4 inhibitor) reduced this conversion with downstream reduction in fibronectin transcription.We wanted to demonstrate that linagliptin reduces high glucose induced interaction between membrane bound DPP4 and CIM6PR in vitro and demonstrate reduction in active TGFß mediated downstream effects in a rodent model of type 1 diabetic nephropathy independent of high glycaemic levels.We used human kidney 2 (HK2) cells and endothelial nitric oxide synthase knock out mice to explore the mechanism and antifibrotic potential of linagliptin independent of glucose lowering. Using a proximity ligation assay, we show that CIM6PR and DPP4 interaction was increased by high glucose and reduced by linagliptin and excess mannose-6-phosphate (M6P) confirming that linagliptin is operating through an M6P-dependent mechanism. In vivo studies confirmed these TGFß1 pathway related changes and showed reduced fibronectin, phosphorylated smad2 and phosphorylated smad2/3 (pSmad2/3) with an associated trend towards reduction in tubular atrophy, which was independent of glucose lowering. No reduction in albuminuria, glomerulosclerotic index or cortical collagen deposition was observed.Linagliptin inhibits activation of TGFß1 through a M6P dependent mechanism. However this in isolation is not sufficient to reverse the multifactorial nature of diabetic nephropathy

The role of TLR2 and 4-mediated inflammatory pathways in endothelial cells exposed to high glucose.

Postprandial hyperglycemia induces inflammation and endothelial dysfunction resulting in vascular complications in patients with diabetes. Toll-like receptors (TLRs) are central to the regulation of inflammatory responses through activation of nuclear factor-kappa B (NF-ĸB). This study examined the role of TLR2 and 4 in regulating inflammation and endothelial dysfunction when exposed to fluctuating glucose concentrations. HMEC-1 cells (a human microvascular endothelial cell line) were exposed to control (5 mM), 30 mM (high), fluctuating (5/30 mM) and 11.2 mM glucose (approximate glycaemic criteria for the diagnosis of diabetes mellitus) for 72 h. Cells were assessed for TLR2, 4, high mobility group box -1 (HMGB1), NF-ĸB, monocyte chemoattractant protein-1 (MCP-1), interleukin-8 (IL-8), intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1). Fluctuating glucose concentrations maximally upregulated TLR4 but not TLR2 expression with increased NF-ĸB activation, IL-8 and ICAM-1 expression. HMGB1 was increased in the supernatants of cells exposed to 30 mM and 11.2 mM glucose compared to control. The addition of recombinant HMGB1 induced NF-ĸB activation and synthesis of proinflammatory cytokines and chemokines, which were prevented by TLR2 or 4 signalling inhibition. An additive effect when both TLR2 and 4 signalling pathways were inhibited was observed. However, only inhibition of TLR4 signalling suppressed the synthesis of MCP-1, IL-8 and ICAM-1. In vivo, streptozotocin-induced diabetic mice exhibited an increase in glomerular ICAM-1 which was not evident in TLR2(-/-) or TLR4(-/-) diabetic mice. Collectively, our results suggest that targeting the signalling pathway of TLR2 and 4 may be of therapeutic benefit in attenuating vascular inflammation in diabetic microangiopathy

Cumulative concentration-response curves to ACh (a), SNP (b), and basal NO release (c) in endothelium-intact mesenteric arteries.

<p>In each group (a, b), mesenteric arteries were prcontracted with PE to a similar levels: (a) normal 66±2, normal+linagliptin 64±1, diabetic 65±1, diabetic+linagliptin 66±1, (b) normal 64±1, normal+linagliptin 64±1, diabetic 61±6, diabetic+linagliptin 66±1%KPSS, n = 7–10 experiments. Results are shown as mean±SEM. **P<0.01, ***P<0.001 See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143941#pone.0143941.t002" target="_blank">Table 2</a> or results section for pEC₅₀ and R_max values derived from this data.</p

ROS measurement in intact mesenteric arteries.

<p>NADPH activity was elevated in diabetic mesenteric arteries and this was attenuated by linagliptin treatment or by DPI (5 μM), a flavoprotein inhibitor that inhibits NADPH oxidase. Results are shown as mean±SEM. n = 7–10 experiments. *P<0.05 vs normal, ^#P<0.05 vs diabetic.</p

Relative contribution of NO and EDH to endothelium-dependent relaxation.

<p>NO and EDH-mediated relaxation in isolated mesenteric arteries from normal (a), diabetic (b), normal+linagliptin (c), diabetic+linagliptin (d) rats. In each group of experiments, arteries were precontracted with PE to similar levels: 63±2 (a), 65±0.6 (b), 65±1 (c), 63±1 (d) %KPSS, n = 8–9 experiments. Results are shown as mean±SEM. See <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0143941#pone.0143941.t002" target="_blank">Table 2</a> for pEC₅₀ and R_max values derived from this data. *P<0.05 vs normal.</p