Platelet-derived exosomes from septic shock patients induce myocardial dysfunction

Abstract\ud \ud \ud \ud Introduction\ud \ud Mechanisms underlying inotropic failure in septic shock are incompletely understood. We previously identified the presence of exosomes in the plasma of septic shock patients. These exosomes are released mainly by platelets, produce superoxide, and induce apoptosis in vascular cells by a redox-dependent pathway. We hypothesized that circulating platelet-derived exosomes could contribute to inotropic dysfunction of sepsis.\ud \ud \ud \ud Methods\ud \ud We collected blood samples from 55 patients with septic shock and 12 healthy volunteers for exosome separation. Exosomes from septic patients and healthy individuals were investigated concerning their myocardial depressant effect in isolated heart and papillary muscle preparations.\ud \ud \ud \ud Results\ud \ud Exosomes from the plasma of septic patients significantly decreased positive and negative derivatives of left ventricular pressure in isolated rabbit hearts or developed tension and its first positive derivative in papillary muscles. Exosomes from healthy individuals decreased these variables non-significantly. In hearts from rabbits previously exposed to endotoxin, septic exosomes decreased positive and negative derivatives of ventricular pressure. This negative inotropic effect was fully reversible upon withdrawal of exosomes. Nitric oxide (NO) production from exosomes derived from septic shock patients was demonstrated by fluorescence. Also, there was an increase in myocardial nitrate content after exposure to septic exosomes.\ud \ud \ud \ud Conclusion\ud \ud Circulating platelet-derived exosomes from septic patients induced myocardial dysfunction in isolated heart and papillary muscle preparations, a phenomenon enhanced by previous in vivo exposure to lipopolysaccharide. The generation of NO by septic exosomes and the increased myocardial nitrate content after incubation with exosomes from septic patients suggest an NO-dependent mechanism that may contribute to myocardial dysfunction of sepsis.This work received financial support from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP).This work received financial support from Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Efeito da solução hipertônica de NaCl 7,5% na resposta inflamatória em modelo de choque hipovolêmico*

A solução hipertônica de cloreto de sódio 7,5% (SSH) é eficaz em restaurar os parâmetros hemodinâmicos e reduzir a inflamação em modelos experimentais de choque hemorrágico. Assim, foi nosso objetivo investigar a ação da SSH sobre os mecanismos envolvidos na lesão de isquemia e reperfusão (I/R) em um modelo de choque hemorrágico controlado. Ratos Wistar (280-350 g) foram submetidos à hemorragia controlada, mantendo-se a pressão arterial média em 40 mmHg por 1 h. Após esse período, os animais foram randomizados e receberam SSH (4 ml/kg) ou solução salina isotônica (SSI-34 ml/kg). Não foram observadas diferenças na resposta hemodinâmica nos dois grupos. Também não foram observadas diferenças na geração espécies reativas de oxigênio (medida indiretamente pela concentração de malondialdeído) ou das citocinas IL-6 e IL-10 (medidas por ELISA). A análise histológica qualitativa dos pulmões mostrou que os animais do grupo SSH apresentaram um menor influxo tecidual de neutrófilos. Esses animais também mostraram maior expressão de proteínas do choque térmico 70 (HSP70). Assim, concluímos que o tratamento do choque hemorrágico com SSH pode diminuir o processo inflamatório pulmonar e aumentar a proteção celular, devido ao aumento da expressão de HSP70.Hypertonic saline solution (HSS - NaCl 7,5%) was shown to restore hemodynamic parameters in hemorrhagic shock and to decrease the inflammation triggered by ischemia reperfusion injury (I/R). Therefore, our objective was to investigate the effects of HSS on the mechanisms involved in I/R, in an experimental model of controled hemorrhagic shock. Wistar rats (280-350 g) were submitted to controled bleeding, keeping the mean arterial pressure around 40 mmHg, for 1 hour. After that, rats were randomized and treated with HSS (4 ml/kg)or normal saline (ISS) (34 ml/kg). There were no differences in hemodynamic parameters between the two groups for at least 2 h after shock. No difference either was observed in reactive oxygen species generation (measured indirectly by malondialdehyde concentration)or cytokines (IL-6 and IL-10) production (measured by ELISA). Qualitative analysis of lung tissue showed a smaller neutrophil infiltrate in animals that received HSS. Also, the animals in the HSS group showed an increased expression of heat shock protein 70 (HSP70). Therefore,we conclude that treatment of hemorrhagic shock with hypertonic saline solution can decrease pulmonary inflammation and increase cellular protection by up-regulating HSP70 expression

The Central Nervous System as Target for Antihypertensive Actions of a Proline-Rich Peptide from Bothrops jararaca Venom

Pyroglutamyl proline-rich oligopeptides, present in the venom of the pit viper Bothrops jararaca (Bj-PROs), are the first described naturally occurring inhibitors of the angiotensin I-converting enzyme (ACE). the inhibition of ACE by the decapeptide Bj-PRO-10c (<ENWPHPQIPP) and other Bj-PROs was classically used to explain the pharmacological effects of these venom peptides in mammals resulting in a decrease of blood pressure. Recent studies, however, suggest that ACE inhibition alone is not sufficient for explaining the antihypertensive actions exerted by these peptides. in this study, we show that intracerebroventricular injection of Bj-PRO-10c induced a significant reduction of mean arterial pressure (MAP) together with a decrease of heart rate (HR) in spontaneously hypertensive rats, indicating that Bj-PRO-10c may act on the central nervous system. in agreement with its supposed neuronal action, this peptide dose-dependently evoked elevations of intracellular calcium concentration ([Ca(2+)](i)) in primary culture from postnatal rat brain. the N-terminal sequence of the peptide was not essential for induction of calcium fluxes, while any changes of C-terminal Pro or Ile residues affected Bj-PRO-10c's activity. Using calcium imaging by confocal microscopy and fluorescence imaging plate reader analysis, we have characterized Bj-PRO-10c-induced [Ca(2+)](i) transients in rat brain cells as being independent from bradykinin-mediated effects and ACE inhibition. Bj-PRO-10c induced pertussis toxin-sensitive G(i/o)-protein activity mediated through a yet unknown receptor, influx and liberation of calcium from intracellular stores, as well as reduction of intracellular cAMP levels. Bj-PRO-10c promoted glutamate and GABA release that may be responsible for its antihypertensive activity and its effect on HR. (C) 2010 International Society for Advancement of CytometryFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Univ São Paulo, Inst Quim, Dept Bioquim, BR-05508900 São Paulo, BrazilInst Butantan, Ctr Appl Toxinol CAT CEPID, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pharmacol, São Paulo, BrazilUniv São Paulo, ESALQ, Dept Ciencias Biol, Lab Bioquim Peptideos & Prot, BR-05508900 São Paulo, BrazilInst Butantan, Lab Bioquim & Biofis, São Paulo, BrazilUniv São Paulo, Dept Dev & Cell Biol, BR-05508900 São Paulo, BrazilUniversidade Federal de São Paulo, Dept Pharmacol, São Paulo, BrazilWeb of Scienc

Brain nitric oxide production by a proline-rich decapeptide from Bothrops jararaca venom improves baroreflex sensitivity of spontaneously hypertensive rats

Baroreflex sensitivity is disturbed in many people with cardiovascular diseases such as hypertension. Brain deficiency of nitric oxide (NO), which is synthesized by NO synthase (NOS) in the citrulline-NO cycle (with argininosuccinate synthase (ASS) activity being the rate-limiting step), contributes to impaired baroreflex. We recently showed that a decapeptide isolated from Bothrops jararaca snake venom, denoted Bj-PRO-10c, exerts powerful and sustained antihypertensive activity. Bj-PRO-10c promoted vasodilatation dependent on the positive modulation of ASS activity and NO production in the endothelium, and also acted on the central nervous system, inducing the release of GABA and glutamate, two important neurotransmitters in the regulation of autonomic systems. We evaluated baroreflex function using the regression line obtained by the best-fit points of measured heart rate (HR) and mean arterial pressure (MAP) data from spontaneously hypertensive rats (SHRs) treated with Bj-PRO-10c. We also investigated molecular mechanisms involved in this effect, both in vitro and in vivo. Bj-PRO-10c mediated an increase in baroreflex sensitivity and a decrease in MAP and HR. The effects exerted by the peptide include an increase in the gene expression of endothelial NOS and ASS. Bj-PRO-10c-induced NO production depended on intracellular calcium fluxes and the activation of a G(i/o)-protein-coupled metabotropic receptor. Bj-PRO-10c induced NO production and the gene expression of ASS and endothelial NOS in the brains of SHRs, thereby improving baroreflex sensitivity. Bj-PRO-10c may reveal novel approaches for treating diseases with impaired baroreflex function. Hypertension Research (2010) 33, 1283-1288; doi: 10.1038/hr.2010.208Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq), BrazilCNP

Exosomes exhibit intrinsic nitric oxide (NO) production and induce myocardial NO production

<p><b>Copyright information:</b></p><p>Taken from "Platelet-derived exosomes from septic shock patients induce myocardial dysfunction"</p><p>http://ccforum.com/content/11/6/R120</p><p>Critical Care 2007;11(6):R120-R120.</p><p>Published online 8 Nov 2007</p><p>PMCID:PMC2246209.</p><p></p> 4,5-diaminofluorescein-2 (DAF-2) fluorescence (an index of NO production) by exosomes from septic shock patients and healthy volunteers. Data are mean ± standard error of the mean (SEM) of six experiments with exosomes from healthy volunteers and septic patients. *< 0.05 versus healthy; < 0.05 versus baseline healthy; < 0.05 versus baseline septic (one-way analysis of variance, Student-Newman-Keuls test). Black bars: baseline septic and healthy exosomes; gray bars: septic and healthy exosomes + superoxide dismutase (SOD) (250 IU/mL); white bars: septic and healthy exosomes + N(G)-nitro-L-arginine methyl ester (L-NAME) (100 μM). Myocardial nitrate content of hearts exposed for 45 minutes to exosomes from septic patients or healthy volunteers. Data are mean ± SEM of four experiments for exosomes of septic patients and healthy volunteers. *< 0.05 versus healthy (test). RFU, relative fluorescence unit

Effect of exosomes on left ventricular pressure in isolated rabbit heart preparations

<p><b>Copyright information:</b></p><p>Taken from "Platelet-derived exosomes from septic shock patients induce myocardial dysfunction"</p><p>http://ccforum.com/content/11/6/R120</p><p>Critical Care 2007;11(6):R120-R120.</p><p>Published online 8 Nov 2007</p><p>PMCID:PMC2246209.</p><p></p> Time course of positive and negative derivatives of left ventricular pressure after infusion of exosomes from septic patients and healthy volunteers. Data are mean ± standard error of the mean of nine experiments for exosomes derived from septic patients and five experiments for exosomes from healthy individuals. *< 0.05 versus baseline; < 0.05 versus 20 minutes (analysis of variance two-way, Tukey test). +dP/dt, maximal positive derivative of left ventricular pressure; -dP/dt, maximal negative derivative of left ventricular pressure

Neotropical freshwater fisheries : A dataset of occurrence and abundance of freshwater fishes in the Neotropics

The Neotropical region hosts 4225 freshwater fish species, ranking first among the world's most diverse regions for freshwater fishes. Our NEOTROPICAL FRESHWATER FISHES data set is the first to produce a large-scale Neotropical freshwater fish inventory, covering the entire Neotropical region from Mexico and the Caribbean in the north to the southern limits in Argentina, Paraguay, Chile, and Uruguay. We compiled 185,787 distribution records, with unique georeferenced coordinates, for the 4225 species, represented by occurrence and abundance data. The number of species for the most numerous orders are as follows: Characiformes (1289), Siluriformes (1384), Cichliformes (354), Cyprinodontiformes (245), and Gymnotiformes (135). The most recorded species was the characid Astyanax fasciatus (4696 records). We registered 116,802 distribution records for native species, compared to 1802 distribution records for nonnative species. The main aim of the NEOTROPICAL FRESHWATER FISHES data set was to make these occurrence and abundance data accessible for international researchers to develop ecological and macroecological studies, from local to regional scales, with focal fish species, families, or orders. We anticipate that the NEOTROPICAL FRESHWATER FISHES data set will be valuable for studies on a wide range of ecological processes, such as trophic cascades, fishery pressure, the effects of habitat loss and fragmentation, and the impacts of species invasion and climate change. There are no copyright restrictions on the data, and please cite this data paper when using the data in publications