Endothelin-1 induces neutrophil recruitment in adaptive inflammation via TNFα and CXCL1/CXCR2 in mice

IL-33 supplementation improves uterine artery resistance and maternal hypertension in response to placental ischemia

Preeclampsia (PE), a leading cause of maternal/fetal morbidity and mortality, is a hypertensive pregnancy disorder with end-organ damage that manifests after 20 wk of gestation. PE is characterized by chronic immune activation and endothelial dysfunction. Clinical studies report reduced IL-33 signaling in PE. We use the Reduced Uterine Perfusion Pressure (RUPP) rat model, which mimics many PE characteristics including reduced IL-33, to identify mechanisms mediating PE pathophysiology. We hypothesized that IL-33 supplementation would improve blood pressure (BP), inflammation, and oxidative stress (ROS) during placental ischemia. We implanted intraperitoneal mini-osmotic pumps infusing recombinant rat IL-33 (1 µg/kg/day) into normal pregnant (NP) and RUPP rats from gestation day 14 to 19. We found that IL-33 supplementation in RUPP rats reduces maternal blood pressure and improves the uterine artery resistance index (UARI). In addition to physiological improvements, we found decreased circulating and placental cytolytic Natural Killer cells (cNKs) and decreased circulating, placental, and renal TH17s in IL-33-treated RUPP rats. cNK cell cytotoxic activity also decreased in IL-33-supplemented RUPP rats. Furthermore, renal ROS and placental preproendothelin-1 (PPET-1) decreased in RUPP rats treated with IL-33. These findings demonstrate a role for IL-33 in controlling vascular function and maternal BP during pregnancy by decreasing inflammation, renal ROS, and PPET-1 expression. These data suggest that IL-33 may have therapeutic potential in managing PE.NEW & NOTEWORTHY Though decreased IL-33 signaling has been clinically associated with PE, the mechanisms linking this signaling pathway to overall disease pathophysiology are not well understood. This study provides compelling evidence that mechanistically links reduced IL-33 with the inflammatory response and vascular dysfunction observed in response to placental ischemia, such as in PE. Data presented in this study submit the IL-33 signaling pathway as a possible therapeutic target for the treatment of PE.

Resveratrol improves hepatic ischemia-reperfusion injury by inhibiting neutrophils via the ERK signaling pathway

Hepatic ischemia-reperfusion injury (HIRI) is the main complication and even mortality in the setting of hepatic surgery or transplantation. Inflammation, especially the neutrophil response, plays important roles during the process of HIRI. In this study, we found that resveratrol preintervention ameliorated IRI-induced hepatic injury and neutrophil inflammatory responses in the liver. Moreover, RNA-sequencing analysis showed that resveratrol inhibited the functions of neutrophils, such as survival, cell cycle, migration and chemotaxis, oxidative stress and secretion of proinflammatory cytokines. Resveratrol restrained oxidative stress and the inflammatory response of neutrophils via inhibition of endothelin 1 autocrine signaling by suppressing the ERK signaling pathway. These data provide more evidence for the immunomodulatory role of resveratrol and enrich our understanding of immune strategies to improve HIRI.

DEspRhigh neutrophils are associated with critical illness in COVID-19

SARS-CoV-2 infection results in a spectrum of outcomes from no symptoms to widely varying degrees of illness to death. A better understanding of the immune response to SARS-CoV-2 infection and subsequent, often excessive, inflammation may inform treatment decisions and reveal opportunities for therapy. We studied immune cell subpopulations and their associations with clinical parameters in a cohort of 26 patients with COVID-19. Following informed consent, we collected blood samples from hospitalized patients with COVID-19 within 72 h of admission. Flow cytometry was used to analyze white blood cell subpopulations. Plasma levels of cytokines and chemokines were measured using ELISA. Neutrophils undergoing neutrophil extracellular traps (NET) formation were evaluated in blood smears. We examined the immunophenotype of patients with COVID-19 in comparison to that of SARS-CoV-2 negative controls. A novel subset of pro-inflammatory neutrophils expressing a high level of dual endothelin-1 and VEGF signal peptide-activated receptor (DEspR) at the cell surface was found to be associated with elevated circulating CCL23, increased NETosis, and critical-severity COVID-19 illness. The potential to target this subpopulation of neutrophils to reduce secondary tissue damage caused by SARS-CoV-2 infection warrants further investigation.

Immune Dysfunction in Uremia 2020

Cardiovascular disease and infections are major causes for the high incidence of morbidity and mortality of patients with chronic kidney disease. Both complications are directly or indirectly associated with disturbed functions or altered apoptotic rates of polymorphonuclear leukocytes, monocytes, lymphocytes, and dendritic cells. Normal responses of immune cells can be reduced, leading to infectious diseases or pre-activated/primed, giving rise to inflammation and subsequently to cardiovascular disease. This review summarizes the impact of kidney dysfunction on the immune system. Renal failure results in disturbed renal metabolic activities with reduced renin, erythropoietin, and vitamin D production, which adversely affects the immune system. Decreased kidney function also leads to reduced glomerular filtration and the retention of uremic toxins. A large number of uremic toxins with detrimental effects on immune cells have been identified. Besides small water-soluble and protein-bound compounds originating from the intestinal microbiome, several molecules in the middle molecular range, e.g., immunoglobulin light chains, retinol-binding protein, the neuropeptides Met-enkephalin and neuropeptide Y, endothelin-1, and the adipokines leptin and resistin, adversely affect immune cells. Posttranslational modifications such as carbamoylation, advanced glycation products, and oxidative modifications contribute to uremic toxicity. Furthermore, high-density lipoprotein from uremic patients has an altered protein profile and thereby loses its anti-inflammatory properties.

Quercetin attenuates zymosan-induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by articular lesions, recruitment of inflammatory cells and increased levels of pro-inflammatory cytokine. The intra-articular administration of zymosan is an experimental model that promotes inflammatory parameters resembling RA. Therefore, this model was used to investigate the efficacy of quercetin as a treatment of articular inflammation. Treatment with quercetin dose-dependently reduced zymosan-induced hyperalgesia, articular edema and the recruitment of neutrophils to the knee joint cavity. Histological analysis confirmed that quercetin inhibited zymosan-induced arthritis. The treatment with quercetin also inhibited zymosan-induced depletion of reduced glutathione (GSH) levels, TNFα and IL-1β production, and gp91^phox, prepro-endothelin-1 (preproET-1), and cyclooxygenase-2 mRNA expression. These molecular effects of quercetin were related to the inhibition of the nuclear factor kappa-B and induction of Nuclear factor erythroid 2- related factor (Nrf2)/home oxygenase (HO-1) pathway. Thus, quercetin exerted anti-inflammatory, analgesic and antioxidant effects in experimental arthritis, suggesting quercetin is a possible candidate for arthritis treatment.

Adamdec1, Ednrb and Ptgs1/Cox1, inflammation genes upregulated in the intestinal mucosa of obese rats, are downregulated by three probiotic strains

We have previously reported that administration of Lactobacillus paracasei CNCM I-4034, Bifidobacterium breve CNCM I-4035 and Lactobacillus rhamnosus CNCM I-4036 to obese Zucker-Lepr fa/fa rats attenuates liver steatosis and exerts anti-inflammatory effects. The goal of the present work was to investigate the modulation of gene expression in intestinal mucosa samples of obese Zucker-Lepr fa/fa rats fed the probiotic strains using a DNA microarray and postgenomic techniques. We also measured secretory IgA content in the gut and lipopolysaccharide (LPS)-binding protein (LBP) in serum. Expression of three genes (Adamdec1, Ednrb and Ptgs1/Cox1) was up-regulated in the intestinal mucosa of the obese rats compared with that in the rats when they were still lean. Probiotic administration down-regulated expression of Adamdec1 and Ednrb at the mRNA and protein levels and that of Ptgs1/Cox1 at the mRNA level, and this effect was in part mediated by a decrease in both macrophage and dendritic cell populations. Probiotic treatment also increased secretory IgA content and diminished the LBP concentration. Based on results reported in this work and else where, we propose a possible mechanism of action for these bacterial strains.

The endothelin B receptor plays a crucial role in the adhesion of neutrophils to the endothelium in sickle cell disease

Although the primary origin of sickle cell disease is a hemoglobin disorder, many types of cells contribute considerably to the pathophysiology of the disease. The adhesion of neutrophils to activated endothelium is critical in the pathophysiology of sickle cell disease and targeting neutrophils and their interactions with endothelium represents an important opportunity for the development of new therapeutics. We focused on endothelin-1, a mediator involved in neutrophil activation and recruitment in tissues, and investigated the involvement of the endothelin receptors in the interaction of neutrophils with endothelial cells. We used fluorescence intravital microscopy analyses of the microcirculation in sickle mice and quantitative microfluidic fluorescence microscopy of human blood. Both experiments on the mouse model and patients indicate that blocking endothelin receptors, particularly ET_B receptor, strongly influences neutrophil recruitment under inflammatory conditions in sickle cell disease. We show that human neutrophils have functional ET_B receptors with calcium signaling capability, leading to increased adhesion to the endothelium through effects on both endothelial cells and neutrophils. Intact ET_B function was found to be required for tumor necrosis factor α-dependent upregulation of CD11b on neutrophils. Furthermore, we confirmed that human neutrophils synthesize endothelin-1, which may be involved in autocrine and paracrine pathophysiological actions. Thus, the endothelin-ET_B axis should be considered as a cytokine-like potent pro-inflammatory pathway in sickle cell disease. Blockade of endothelin receptors, including ET_B, may provide major benefits for preventing or treating vaso-occlusive crises in sickle cell patients.

Potential role for ET-2 acting through ETA receptors in experimental colitis in mice

OBJECTIVE AND DESIGN

This study attempted to clarify the roles of endothelins and mechanisms associated with ET_A/ET_B receptors in mouse models of colitis.

MATERIALS AND METHODS

Colitis was induced by intracolonic administration of 2,4,6-trinitrobenzene sulfonic acid (TNBS, 1.5 mg/animal) or dextran sulfate sodium (DSS, 3%). After colitis establishment, mice received Atrasentan (ET_A receptor antagonist, 10 mg/kg), A-192621 (ET_B receptor antagonist, 20 mg/kg) or Dexamethasone (1 mg/kg) and several inflammatory parameters were assessed, as well as mRNA levels for ET-1, ET-2 and ET receptors.

RESULTS

Atrasentan treatment ameliorates TNBS- and DSS-induced colitis. In the TNBS model was observed reduction in macroscopic and microscopic score, colon weight, neutrophil influx, IL-1β, MIP-2 and keratinocyte chemoattractant (KC) levels, inhibition of adhesion molecules expression and restoration of IL-10 levels. However, A192621 treatment did not modify any parameter. ET-1 and ET-2 mRNA was decreased 24 h, but ET-2 mRNA was markedly increased at 48 h after TNBS. ET-2 was able to potentiate LPS-induced KC production in vitro. ET_A and ET_B receptors mRNA were increased at 24, 48 and 72 h after colitis induction.

CONCLUSIONS

Atrasentan treatment was effective in reducing the severity of colitis in DSS- and TNBS-treated mice, suggesting that ET_A receptors might be a potential target for inflammatory bowel diseases.

Differential regulation of oxidative stress and cytokine production by endothelin ETA and ETB receptors in superoxide anion-induced inflammation and pain in mice

The present study investigated whether endothelin-1 acts via ET_A or ET_B receptors to mediate superoxide anion-induced pain and inflammation. Mice were treated with clazosentan (ET_A receptor antagonist) or BQ-788 (ET_B receptor antagonist) prior to stimulation with the superoxide anion donor, KO₂. Intraplantar treatment with 30 nmol of clazosentan or BQ-788 reduced mechanical hyperalgesia (47% and 42%), thermal hyperalgesia (68% and 76%), oedema (50% and 30%); myeloperoxidase activity (64% and 32%), and overt-pain like behaviours, such as paw flinching (42% and 42%) and paw licking (38% and 62%), respectively. Similarly, intraperitoneal treatment with 30 nmol of clazosentan or BQ-788 reduced leukocyte recruitment to the peritoneal cavity (58% and 32%) and abdominal writhing (81% and 77%), respectively. Additionally, intraplantar treatment with clazosentan or BQ-788 decreased spinal (45% and 41%) and peripheral (47% and 47%) superoxide anion production as well as spinal (47% and 47%) and peripheral (33% and 54%) lipid peroxidation, respectively. Intraplantar treatment with clazosentan, but not BQ-788, reduced spinal (71%) and peripheral (51%) interleukin-1 beta as well as spinal (59%) and peripheral (50%) tumor necrosis factor-alpha production. Therefore, the present study unveils the differential mechanisms by which ET-1, acting on ET_A or ET_B receptors, regulates superoxide anion-induced inflammation and pain.

Human Cytomegalovirus Up-Regulates Endothelin Receptor Type B: Implication for Vasculopathies?

Background. Both endothelin receptor type B ([ET_BR], a G protein-coupled receptor that mediates the vascular effects of the potent vasoconstrictor endothelin-1) and human cytomegalovirus ([HCMV], a ubiquitous herpesvirus) have been implicated in the pathogenesis of cardiovascular disease (CVD). The effects of HCMV infection on ET_BR expression are unknown. We hypothesized that HCMV may contribute to the pathogenesis of CVD via ET_BR modulation.

Methods. Human CMV effects on ET_BR were studied in vitro in endothelial cells (ECs) and smooth muscle cells (SMCs) and ex vivo in human carotid plaque tissue specimens. Expression of ET_BR and viral immediate-early were quantified using quantitative polymerase chain reaction. Functional consequences after ET_BR blockade in ECs were examined by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide proliferation, wound healing, tube formation, and flow adhesion assays.

Results. Human CMV is capable of upregulating both ET_BR mRNA and protein expression in ECs and SMCs. The ET_BR was also abundantly expressed in ECs, foam cells, and SMCs, and, more importantly, in HCMV-positive cells in human carotid plaques. Endothelin receptor type B blockade led to decreased proliferation and reduced tumor necrosis factor α-mediated leukocyte recruitment in both uninfected and HCMV-infected ECs. Direct HCMV infection was antimigratory and antiangiogenic in ECs.

Conclusions. Human CMV may contribute to CVD via ET_BR induction.

Bosentan, a mixed endothelin receptor antagonist, inhibits superoxide anion-induced pain and inflammation in mice

Bosentan is a mixed endothelin receptor antagonist widely used to treat patients with pulmonary arterial hypertension, and the emerging literature suggests bosentan as a potent anti-inflammatory drug. Superoxide anion is produced in large amounts during inflammation, stimulates cytokine production, and thus contributes to inflammation and pain. However, it remains to be determined whether endothelin contributes to the inflammatory response triggered by the superoxide anion. The present study investigated the effects of bosentan in a mouse model of inflammation and pain induced by potassium superoxide, a superoxide anion donor. Male Swiss mice were treated with bosentan (10-100 mg/kg) by oral gavage, 1 h before potassium superoxide injection, and the inflammatory response was evaluated locally and at spinal cord (L4-L6) levels. Bosentan (100 mg/kg) inhibited superoxide anion-induced mechanical and thermal hyperalgesia, overt pain-like behavior (abdominal writhings, paw flinching, and licking), paw edema, myeloperoxidase activity (neutrophil marker) in the paw skin, and leukocyte recruitment in the peritoneal cavity. Bosentan also inhibited superoxide anion-induced interleukin-1 beta (IL-1β) and tumor necrosis factor alpha (TNF-α) production, while it enhanced IL-10 production in the paw skin and spinal cord. Bosentan inhibited the reduction of antioxidant capacity (reduced glutathione, ferric reducing antioxidant power, and ABTS radical scavenging ability) induced by the superoxide anion. Finally, we demonstrated that intraplantar injection of potassium superoxide induces the mRNA expression of prepro-endothelin-1 in the paw skin and spinal cord. In conclusion, our results demonstrated that superoxide anion-induced inflammation, pain, cytokine production, and oxidative stress depend on endothelin; therefore, these responses are amenable to bosentan treatment.

IL-33/ST2 signalling contributes to carrageenin-induced innate inflammation and inflammatory pain: role of cytokines, endothelin-1 and prostaglandin E2

BACKGROUND AND PURPOSE

IL-33 signals through ST2 receptors and induces adaptive and innate inflammation. IL-33/ST2 is involved in adaptive inflammation-induced pain. Here, we have investigated the contribution of IL-33/ST2-triggered mechanisms to carrageenin-induced innate inflammation.

EXPERIMENTAL APPROACH

Carrageenin- and IL-33-induced inflammatory responses were assessed in BALB/c- (WT) and ST2-deficient ((-/-) ) mice as follows: oedema (plethysmometer), myeloperoxidase activity (colorimetric assay), mechanical hyperalgesia (electronic version of von Frey filaments), cytokine levels (ELISA), PGE2 (RIA), mRNA expression (quantitative PCR), drug treatments targeting leukocyte recruitment (fucoidin), TNF-α (infliximab), CXCL1 (antibody to CXCL1), IL-1 (IL-1ra), endothelin ETA (clazosentan) and ETB (BQ788) receptors and COX (indomethacin).

KEY RESULTS

Carrageenin injection increased ST2 and IL-33 mRNA expression and IL-33 production in paw skin samples. Carrageenin-induced paw oedema, hyperalgesia and myeloperoxidase activity were reduced in ST2(-/-) compared with WT mice, effects mimicked by IL-33 injection in the paw. Furthermore, IL-33-induced hyperalgesia was reduced by fucoidin suggesting a role for recruited leukocytes in its hyperalgesic effect. IL-33-induced hyperalgesia in naïve mice was reduced by treatments targeting TNF, CXCL1, IL-1, endothelin receptors and COX while carrageenin-induced ST2-dependent TNF-α, CXCL1, IL-1β, IL-10 and PGE2 production and preproET-1 mRNA expression. Combining IL-33 and carrageenin at doses that were ineffective as single treatment induced significant hyperalgesia, oedema, myeloperoxidase activity and cytokine production in a ST2-dependent manner.

CONCLUSIONS AND IMPLICATIONS

IL-33/ST2 signalling triggers the production of inflammatory mediators contributing to carrageenin-induced inflammation. These data reinforces the importance of IL-33/ST2 signalling as a target in innate inflammation and inflammatory pain.

HJP272, a novel endothelin receptor antagonist, attenuates lipopolysaccharide-induced acute lung injury in hamsters

INTRODUCTION

Previous studies from this laboratory indicate that endothelin-1 (ET-1), a potent vasoconstrictor, may play an important role in lipopolysaccharide (LPS)-induced release of neutrophils from the pulmonary microvasculature. To further test this concept, Syrian hamsters were treated with a novel endothelin receptor A (ETA) antagonist (HJP272) prior to intratracheal instillation of LPS.

METHODS

The effect of HJP272 on the LPS-induced inflammatory reaction was determined by measuring: (1) lung histopathological changes, (2) total neutrophils in bronchoalveolar lavage fluid (BALF), (3) expression of tumor necrosis factor receptor 1 (TNFR1) by BALF macrophages, and (4) alveolar septal cell apoptosis.

RESULTS

Treatment with HJP272 significantly reduced each of these parameters during a 24-hr period following LPS instillation, supporting the concept that limiting the activity of ET-1 may reduce the extent of lung injury. This hypothesis was further tested by giving ET-1 prior to LPS instillation, which resulted in a marked enhancement of LPS-induced lung inflammation, as measured by BALF neutrophils and TNFR1-positive macrophages. Furthermore, the increase in neutrophils resulting from treatment with ET-1 was significantly reduced by HJP272, again demonstrating the ability of ETA receptor antagonists to limit the influx of these cells into the lung.

CONCLUSIONS

These findings suggest a potential therapeutic role for these agents in diseases where neutrophils are a significant cause of lung injury, such as bronchopneumonia, respiratory distress syndrome, and chronic obstructive pulmonary disease.

Heparin-binding protein (HBP/CAP37) - a link to endothelin-1 in endotoxemia-induced pulmonary oedema?

BACKGROUND

Vascular leakage and oedema formation are key components in sepsis. In septic patients, plasma levels of the vasoconstrictive and pro-inflammatory peptide endothelin-1 (ET-1) correlate with mortality. During sepsis, neutrophils release heparin-binding protein (HBP) known to increase vascular permeability and to be a promising biomarker of human sepsis. As disruption of ET-signalling in endotoxemia attenuates formation of oedema, we hypothesized that this effect could be related to decreased levels of HBP. To investigate this, we studied the effects of ET-receptor antagonism on plasma HBP and oedema formation in a porcine model of sepsis. In addition, to further characterize a potential endothelin/HBP interaction, we investigated the effects of graded ET-receptor agonist infusions.

METHODS

Sixteen anesthetized pigs were subjected to 5 h of endotoxemia and were randomized to receive either the ET-receptor antagonist tezosentan or vehicle after 2 h. Haemodynamics, gas-exchange and lung water were monitored. In separate experiments, plasma HBP was measured in eight non-endotoxemic animals exposed to graded infusion of ET-1 or sarafotoxin 6c.

RESULTS

Endotoxemia increased plasma ET-1, plasma HBP, and extravascular lung water. Tezosentan-treatment markedly attenuated plasma HBP and extravascular lung water, and these parameters correlated significantly. Tezosentan decreased pulmonary vascular resistance and increased respiratory compliance. In non-endotoxemic pigs graded ET-1 and sarafotoxin 6c infusions caused a dose-dependent increase in plasma HBP.

CONCLUSIONS

ET-receptor antagonism reduces porcine endotoxin-induced pulmonary oedema and plasma levels of the oedema-promoting protein HBP. Moreover, direct ET-receptor stimulation distinctively increases plasma HBP. Together, these results suggest a novel mechanism by which ET-1 contributes to formation of oedema during experimental sepsis.

Targeting endothelin receptors A and B attenuates the inflammatory response and improves locomotor function following spinal cord injury in mice

After spinal cord injury (SCI), the disruption of blood-spinal cord barrier by activation of the endothelin (ET) system is a critical event leading to leukocyte infiltration, inflammatory response and oxidative stress, contributing to neurological disability. In the present study, we showed that blockade of ET receptor A (ETAR) and/or ET receptor B (ETBR) prevented early inflammatory responses directly via the inhibition of neutrophil and monocyte diapedesis and inflammatory mediator production following traumatic SCI in mice. Long-term neurological improvement, based on a series of tests of locomotor performance, occurred only in the spinal cord‑injured mice following blockade of ETAR and ETBR. We also examined the post‑traumatic changes of the micro-environment within the injured spinal cord of mice following blockade of ET receptors. Oxidative stress reflects an imbalance between malondialdehyde and superoxide dismutase in spinal cord‑injured mice treated with vehicle, whereas blockade of ETAR and ETBR reversed the oxidation state imbalance. In addition, hemeoxygenase-1, a protective protease involved in early SCI, was increased in spinal cord‑injured mice following the blockade of ETAR and ETBR, or only ETBR. Matrix metalloproteinase-9, a tissue-destructive protease involved in early damage, was decreased in the injured spinal cord of mice following blockade of ETAR, ETBR or a combination thereof. The findings of the present study therefore suggested an association between ETAR and ETBR in regulating early pathogenesis of SCI and determining the outcomes of long‑term neurological recovery.

Treatment of mice with cromolyn sodium after reperfusion, but not prior to ischemia, attenuates small intestinal ischemia-reperfusion injury

Stabilizing mast cells (MCs) can either inhibit or augment inflammation; however, how improved therapeutic benefits against small intestinal ischemia-reperfusion injury (IIRI) can be achieved by stabilizing MCs remains to be elucidated. The present study was designed to evaluate different treatments with cromolyn sodium (CS, an MC stabilizer), which was administrated either prior to ischemia or after reperfusion. Kunming mice were randomized into a sham-operated group (SH), a sole IIR group (M), in which mice were subjected to 30 min superior mesenteric artery occlusion followed by 3 day or 3 h reperfusion, or IIR, treated with CS 15 min prior to ischemia or 15 min after reperfusion in the PreCr and PostCr groups. The survival rate and Chiu's scores were evaluated. The levels of ET-1, histamine, TNF-α and IL-6, and expression of MC protease 7 (MCP7), MC counts and myeloperoxidase (MPO) activity were quantified. IIR resulted in severe injury as demonstrated by significant increases in mortality and injury score. IIR also led to substantial elevations in the levels of ET-1, histamine, TNF-α and IL-6, expression of MCP7, MC counts and MPO activities (P<0.05, M vs. SH groups). All biochemical changes were markedly reduced in the PostCr group (P<0.05, PostCr vs. M groups), whereas pretreatment of IIR mice with CS prior to ischemia exhibited no changes of ET-1 levels, injury score and inflammation (P>0.05, PreCr vs. M groups). In conclusion, administration of CS after reperfusion, but not prior to ischemia, attenuates IIRI by downregulating ET-1 and suppressing sustained MC activation.

Analgesic activity of piracetam: effect on cytokine production and oxidative stress

Piracetam is a prototype of nootropic drugs used to improve cognitive impairment. However, recent studies suggest that piracetam can have analgesic and anti-inflammatory effects. Inflammatory pain is the result of a process that depends on neutrophil migration, cytokines and prostanoids release and oxidative stress. We analyze whether piracetam has anti-nociceptive effects and its mechanisms. Per oral pretreatment with piracetam reduced in a dose-dependent manner the overt pain-like behavior induced by acetic acid, phenyl-p-benzoquinone, formalin and complete Freund's adjuvant. Piracetam also diminished carrageenin-induced mechanical and thermal hyperalgesia, myeloperoxidase activity, and TNF-α-induced mechanical hyperalgesia. Piracetam presented analgesic effects as post-treatment and local paw treatment. The analgesic mechanisms of piracetam were related to inhibition of carrageenin- and TNF-α-induced production of IL-1β as well as prevention of carrageenin-induced decrease of reduced glutathione, ferric reducing ability and free radical scavenging ability in the paw. These results demonstrate that piracetam presents analgesic activity upon a variety of inflammatory stimuli by a mechanism dependent on inhibition of cytokine production and oxidative stress. Considering its safety and clinical use for cognitive function, it is possible that piracetam represents a novel perspective of analgesic.

Vasoregulatory peptides pro-endothelin-1 and pro-adrenomedullin are associated with metabolic syndrome in the population-based KORA F4 study

BACKGROUND

Metabolic alterations and endothelial dysfunction are interrelated processes in type 2 diabetes (T2D) and metabolic syndrome (MetS) that often develop in parallel. We assessed the association of vasoactive precursor peptides (VPPs) with MetS and T2D.

DESIGN AND METHODS

Plasma levels of C-terminal pro-endothelin-1 (CT-proET-1) and midregional pro-adrenomedullin (MR-proADM) were measured by novel sensitive assays in 1590 participants of the population-based KORA F4 study. The association of the VPPs with T2D, MetS defined by IDF criteria, the components of MetS, and insulin resistance (IR) was assessed in logistic regression models.

RESULTS

Elevated levels of CT-proET-1 and MR-proADM were associated with T2D, MetS, and IR in age- and sex-adjusted models. After adjustment for age, sex, former vascular complications, lifestyle factors, high-sensitive C-reactive protein, and serum creatinine, significant associations with MetS were found for MR-proADM (OR=5.94, 95% CI 3.78-9.33) and CT-proET-1 (OR=5.18, 95% CI 3.48-7.71) (top quartile vs bottom quartile). CT-proET-1 and MR-proADM were strongly associated with all components of MetS as defined by IDF criteria. After multivariable adjustment, association of CT-proET-1 and MR-proADM with pathological glucose tolerance and T2D disappeared and a borderline association with IR was found only for CT-proET-1 (OR=1.34, 95% CI 0.96-1.87).

CONCLUSIONS

We here demonstrate for the first time that plasma levels of both MR-proADM and CT-proET-1 levels are related to MetS and its components, thus suggesting that they possibly have a role as a surrogate biomarker for the disease and its complications.