Proinsulin c-peptide exerts beneficial effects in endotoxic shock in mice

Vish, Michael; Mangeshkar, Prajakta; Piraino, Giovanna; Denenberg, Alvin; Hake, Paul W.; O’Connor, Michael; Zingarelli, Basilia

doi:10.1097/01.ccm.0000260245.61343.b3

Cited by 35 publications

(54 citation statements)

References 47 publications

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“…Overall, these data seem to point to an anti-inflammatory effect of C-peptide on the endothelium, especially in conditions of insult. This hypothesis is supported by recent in vivo data showing that survival rates of mice following endotoxic shock is improved after C-peptide administration [37]. In these mice, plasma levels of the pro-inflammatory cytokines TNF-α and MCP-1 were also decreased, suggesting a decreased generalised inflammatory response [37].…”

Section: Discussionsupporting

confidence: 73%

Human C-peptide antagonises high glucose-induced endothelial dysfunction through the nuclear factor-κB pathway

et al. 2008

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Aims/hypothesis Endothelial dysfunction in diabetes is predominantly caused by hyperglycaemia leading to vascular complications through overproduction of oxidative stress and activation of the transcription factor nuclear factor-κB (NF-κB). Many studies have suggested that decreased circulating levels of C-peptide may play a role in diabetic vascular dysfunction. To date, the possible effects of C-peptide on endothelial cells and intracellular signalling pathways are largely unknown. We therefore investigated the effect of C-peptide on several biochemical markers of endothelial dysfunction in vitro. To gain insights into potential intracellular signalling pathways affected by C-peptide, we tested NF-κB activation, since it is known that inflammation, secondary to oxidative stress, is a key component of vascular complications and NF-κB is a redox-dependent transcription factor. Methods Human aortic endothelial cells (HAEC) were exposed to 25 mmol/l glucose in the presence of C-peptide (0.5 nmol/l) for 24 h and tested for expression of the gene encoding vascular cell adhesion molecule-1 (VCAM-1) by RT-PCR and flow cytometry. Secretion of IL-8 and monocyte chemoattractant protein-1 (MCP-1) was measured by ELISA. NF-κB activation was analysed by immunoblotting and ELISA. Results Physiological concentrations of C-peptide affect high glucose-induced endothelial dysfunction by: (1) decreasing VCAM-1 expression and U-937 cell adherence to HAEC; (2) reducing secretion of IL-8 and MCP-1; and (3) suppressing NF-κB activation. Conclusions/interpretation During hyperglycaemia, Cpeptide directly affects VCAM-1 expression and both MCP-1 and IL-8 HAEC secretion by reducing NF-κB activation. These effects suggest a physiological anti-inflammatory (and potentially anti-atherogenic) activity of C-peptide on endothelial cells.

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Section: Discussionsupporting

confidence: 73%

Human C-peptide antagonises high glucose-induced endothelial dysfunction through the nuclear factor-κB pathway

et al. 2008

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“…Our results provide a mechanism through which a decrease in PPARγ in sepsis may be partially explained and are consistent with previous results demonstrated in endotoxic shock (19). We hypothesized that posttranslational modifications, including phosphorylation of PPARγ by ERK1/2, may alter PPARγ in a model of polymicrobial sepsis.…”

Section: R E S E a R C H A R T I C L E M O L M Esupporting

confidence: 80%

“…An alternative mechanism resulting in decreased nuclear PPARγ expression and activity could occur through direct interaction of nuclear PPARγ with MEKs, resulting in the nuclear export of PPARγ, thereby preventing its nuclear activation (22). Thus, it is possible that during the inflammatory process, alteration of protein conformation by posttranslational mechanisms may affect the expression of the receptor (19).…”

Section: R E S E a R C H A R T I C L E M O L M Ementioning

confidence: 99%

Phosphorylation of Extracellular Signal-Regulated Kinase (ERK)-1/2 Is Associated with the Downregulation of Peroxisome Proliferator-Activated Receptor (PPAR)-γ during Polymicrobial Sepsis

Kaplan

Hake

Denenberg

et al. 2010

Mol Med

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Peroxisome proliferator-activated receptor (PPAR)-γ is a ligand-activated transcription factor and regulates inflammation. Posttranslational modifications regulate the function of PPARγ, potentially affecting inflammation. PPARγ contains a mitogen-activated protein kinase (MAPK) site, and phosphorylation by extracellular signal-regulated kinase (ERK)-1/2 leads to inhibition of PPARγ. This study investigated the kinetics of PPARγ expression and activation in parenchymal and immune cells in sepsis using the MAPK/ERK kinase (MEK)-1 inhibitor, an upstream kinase of ERK1/2. Adult male Sprague Dawley rats were subjected to polymicrobial sepsis by cecal ligation and puncture. Rats received intraperitoneal injection of vehicle or the MEK1 inhibitor PD98059 (5 mg/kg) 30 min before cecal ligation and puncture. Rats were euthanized at 0, 1, 3, 6 and 18 h after cecal ligation and puncture. Control animals used were animals at time 0 h. Lung, plasma and peripheral blood mononuclear cells (PBMCs) were collected for biochemical assays. In vehicle-treated rats, polymicrobial sepsis resulted in significant lung injury. In the lung and PBMCs, nuclear levels of PPARγ were decreased and associated with an increase in phosphorylated PPARγ and phosphorylated ERK1/2 levels. Treatment with the MEK1 inhibitor increased the antiinflammatory plasma adipokine adiponectin, restored PPARγ expression in PBMCs and lung, and decreased lung injury. The inflammatory effects of sepsis cause changes in PPARγ expression and activation, in part, because of phosphorylation of PPARγ by ERK1/2. This phosphorylation can be reversed by ERK1/2 inhibition, thereby improving lung injury.

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“…Once secreted into the bloodstream, Cpeptide circulates at low nanomolar concentrations in healthy individuals, but it is absent in most patients with type 1 diabetes [1]. In recent years, C-peptide has been shown to exert insulin-independent biological effects on a variety of cells, where it affects the activation of several intracellular pathways, such as, but not limited to, those involved in cellular proliferation and inflammation [2][3][4]. Importantly, C-peptide has been demonstrated to be beneficial when administered as replacement therapy to type 1 diabetes patients who suffer from some diabetic complications [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

C-peptide is internalised in human endothelial and vascular smooth muscle cells via early endosomes

et al. 2009

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Aims/hypothesis There is increasing evidence that Cpeptide exerts intracellular effects in a variety of cells and could be beneficial in patients with type 1 diabetes. Exactly how C-peptide achieves these effects, however, is unknown. Recent reports showed that C-peptide internalised in the cytoplasm of HEK-293 and Swiss 3T3 cells, where it was not degraded for at least 1 h after uptake. In this study, we investigated the hypothesis that C-peptide is internalised via an endocytic pathway and traffics to classic endocytic organelles, such as endosomes and lysosomes. Methods We studied the internalisation of C-peptide in vascular endothelial and smooth muscle cells, two relevant targets of Cpeptide activity, by using Alexa Fluor-labelled C-peptide probes in living cells and immunohistochemistry employing confocal laser-scanning microscopy. To examine trafficking to subcellular compartments, we used fluorescent constructs tagged to RAB5A, member RAS oncogene family (RAB5A) to identify early endosomes, or to lysosomal-associated membrane protein 1 (LAMP1) to identify lysosomes.Results C-peptide internalised in the cytoplasm of cells within punctate structures identified as early endosomes. Internalisation was clearly detectable after 10 min of incubation and was blocked at 4°C as well as with excess of unlabelled C-peptide. A minor fraction of vesicles, which increased with culture time, co-localised with lysosomes. Uptake of C-peptide was reduced by monodansylcadaverine, a pharmacological compound that blocks clathrin-mediated endocytosis, and by nocodazole, which disrupts microtubule assembly. Conclusions/interpretation C-peptide internalises in the cytoplasm of cells by endocytosis, as demonstrated by its localisation in early endosomes. Endosomes might represent a signalling station, through which C-peptide might achieve its cellular effects.

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Proinsulin c-peptide exerts beneficial effects in endotoxic shock in mice

Abstract: Our data show that c-peptide has beneficial effects in endotoxic shock, and this therapeutic effect is associated with activation of proliferator-activated receptor-gamma.

Cited by 35 publications

References 47 publications

Human C-peptide antagonises high glucose-induced endothelial dysfunction through the nuclear factor-κB pathway

Human C-peptide antagonises high glucose-induced endothelial dysfunction through the nuclear factor-κB pathway

Phosphorylation of Extracellular Signal-Regulated Kinase (ERK)-1/2 Is Associated with the Downregulation of Peroxisome Proliferator-Activated Receptor (PPAR)-γ during Polymicrobial Sepsis

C-peptide is internalised in human endothelial and vascular smooth muscle cells via early endosomes

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