The clinical use of classical glucocorticoids (GC) is narrowed by the many side effects it causes and the resistance to GC observed in some diseases. Since the great majority of GC effects depend on the activation of a glucocorticoid receptor (GR), many research groups had focused to better understand the signaling pathways involving those receptors. Transgenic animal models and genetic modifications of the receptor brought a huge insight into GR mechanisms of action. This in turn opened a new window for the search of selective GR modulators that ideally may have agonistic and antagonistic combined effects and activate one specific signaling pathway, inducing mostly transrepression or transactivation mechanisms. Another important research field concerns to posttranslational modifications that affect the GR and consequently also affect its signaling and function. In this mini review, we discuss many of those aspects of GR signaling, as well as findings like the ligand-independent activation of GR, which add another layer of complexity in GR signaling pathways. Although several recent data have been added to the GR field, much work has yet to be done, especially to find out the biological relevance of those alternative GR signaling pathways. Improving the knowledge about alternative GR signaling pathways and understanding how these pathways intercommunicate and in which situations they are relevant might help to develop new strategies to take benefit of it and to improve GC or other compounds efficacy causing minimal side effects.
Lipoxin A4 (LXA4) is an endogenous lipid mediator with potent anti-inflammatory actions but its role in infectious processes is not well understood. We investigated the involvement of LXA4 and its receptor FPR2/ALX in the septic inflammatory dysregulation. Pneumosepsis was induced in mice by inoculation of Klebsiella pneumoniae. LXA4 levels and FPR2/ALX expression in the infectious focus as well as the effects of treatment with receptor agonists (LXA4 and BML-111) and antagonists (BOC-2 and WRW(4)) in early (1h) and late (24h) sepsis were studied. Sepsis induced an early increase in LXA4, FPR2/ALX lung expression, local and systemic infection and inflammation, and mortality. Treatment with BOC-2 in early sepsis increased leukocyte migration to the focus, and reduced bacterial load and dissemination. Inhibition of 5- and 15-lipoxygenase in early sepsis also increased leukocyte migration. Early treatment with WRW(4) and BOC-2 improved survival. Treatment with authentic LXA4 or BML-111 in early sepsis decreased cell migration and worsened the infection. In late sepsis, treatment with BOC-2 had no effect, but LXA4 improved the survival rate by reducing the excessive inflammatory response, this effect being abolished by pretreatment with BOC-2. Thus, the anti-inflammatory and pro-resolution mediator LXA4 and its receptor FPR2/ALX levels were increased in the early phase of sepsis, contributing to the septic inflammatory dysregulation. In addition, LXA4 has a dual role in sepsis and that its beneficial or harmful effects are critically dependent on the time. Therefore, a proper interference with LXA4 system may be a new therapeutic avenue to treat sepsis.
Sepsis induces increased expression and physical association of nitric oxide synthase 1/soluble guanylate cyclase and a higher production of cyclic guanosine monophosphate that together may help explain sepsis-induced vascular dysfunction. In addition, selective inhibition of nitric oxide synthase 1 restores the responsiveness to vasoconstrictors. Therefore, inhibition of nitric oxide synthase 1 (and possibly soluble guanylate cyclase) may represent a valuable alternative to restore the effectiveness of vasopressor agents during late sepsis.
We investigated long-lasting changes in endothelial and vascular function in adult rat survivors of severe sepsis induced by cecal ligation and puncture (CLP) model. For this, male Wistar rats (200–350 g) had their cecum punctured once (non-transfixing hole) with a 14-gauge needle. Performed in this way, a mortality rate around 30% was achieved in the first 72 h. The survivors, together with age-matched control rats (not subjected to CLP), were maintained in our holding room for 60 days (S60 group) and had the descending thoracic aorta processed for functional, histological, biochemical or molecular analyses. Endothelium-intact aortic rings obtained from sepsis-surviving S60 group displayed increased angiotensin II-induced contraction, accompanied by decreased activity of the endogenous superoxide dismutase, augmented reactive oxygen species generation, and increased levels of tyrosine nitration compared with vessels from control group. The superoxide scavengers superoxide dismutase and tempol, and the antioxidant apocynin, were able to avoid this enhanced contractility to angiotensin II in aortic rings from the S60 group. In addition, aortic rings from the S60 group presented reduced sensitivity to Y-27632, a Rho-kinase (ROCK) inhibitor. Immunoblot analyses revealed augmented RhoA and ROCK II, and high levels of phosphorylation of myosin phosphatase target subunit 1 in vessels from S60 rats. In conclusion, aortic rings from sepsis-surviving rats display endothelial dysfunction mediated by the increased production of reactive oxygen species, which in turn reduces the bioavailability of nitric oxide and increases the formation of peroxynitrite, and enhances RhoA-ROCK-mediated calcium sensitization, leading to augmented contractile responses to angiotensin II. Notably, this is the first study demonstrating long-term dysfunction in the vasculature of sepsis-surviving rats, which take place or remain beyond the acute septic insult.
Background: We hypothesized that one single episode of acute kidney injury (AKI) reduces long-term survival compared with no acute kidney injury (No AKI) following recovery from critical illness. Materials and methods: A prospective cohort of 2,010 patients admitted to the ICU between 2000 and 2009 at a provincial referral hospital was followed to determine whether AKI influences long-term survival. Results: Of the 1,844 eligible patients, 18.4% had AKI stage 1, 12.1% had stage 2, 26.5% had stage 3, and 43.0% had No AKI, using the KDIGO classification. The mean and median follow-up time was 8.1 and 8.7 years. The 28-day, 1-year, 5-year and 10-year survival rates were 59.6%, 44.9%, 37.4%, and 33.4%, in patients with any AKI (stage 1, stage 2, stage 3), which was significantly worse compared with the critically ill patients with no AKI at any time (P < 0.01). The adjusted 10-year mortality risk associated with AKI was 1.44 (95% CI = 1.2 to 1.7) among 28-day survivors. Patients who had mild AKI (stage 1) had significantly worse survival at 28 days, 1 year, 3 years, 5 years and 10 years compared with No AKI (P < 0.01) ( Figure 1A). Patients with sepsis and AKI who survived 28 days had significantly poorer 5-year and 10-year survival compared with nonseptic AKI (P < 0.01) ( Figure 1B). Conclusions: Patients with one episode of mild (stage 1) AKI have significantly lower survival rates over 10 years than critically ill patients without AKI. The causes and mechanisms of this association warrant further careful study. Close medical follow-up of these patients may be warranted and mechanistic research required understanding how AKI influences distant events. P3Heparin-binding protein improves prediction of severe sepsis in the emergency departmentBackground: The early identification of risk of developing severe sepsis in patients with suspected infection remains a difficult challenge. We hypothesized that an elevated plasma level of heparin-binding protein (HBP), a neutrophil-secreted mediator of vascular leakage, would be a predictor of delayed clinical deterioration and progressive organ dysfunction in emergency department (ED) sepsis patients. Materials and methods: A prospective, multicenter study in Sweden and the US was conducted of 763 patients presenting to an ED with a suspected infection and signs of systemic inflammation. Based on recorded clinical and laboratory parameters and final diagnoses, patients were classified into various groups depending on the severity of the infection and inflammatory response. Plasma levels of HBP were measured and compared with levels of other standard sepsis biomarkers including procalcitonin, lactate, WBC, and C-reactive protein.Results: The final diagnoses were severe sepsis with organ failure in 338 patients, nonsevere sepsis without organ failure in 340 patients, and no infection in 85 patients. One-hundred and forty-three patients (19%) presented without signs of severe sepsis, but developed delayed circulatory failure and/or organ dysfunction within 72 hours of enrolment. ...
We hypothesized that changes in vascular reactivity contribute to the high mortality rate among patients discharged after severe sepsis/septic shock. Male Wistar rats were subjected to cecal ligation and puncture to induce sepsis (mortality around 30%) and aortic rings from survived animals were tested at 30 or 60 days after (S30 and S60 groups). The effects of KCl, phenylephrine, angiotensin I, CaCl2, acetylcholine and sodium nitroprusside did not change, but angiotensin II (AII)‐induced constriction was increased by 80% in aortic rings from S60. The removal of endothelium, incubation with L‐NAME (inhibitor of nitric oxide synthase), or inhibition of Rho‐kinase by Y‐27632 did not change the effects of AII in these vessels, which showed increased protein levels of both RhoA and ROCK II. Incubation with apocynin (NADPH oxidase inhibitor), SOD, or tempol (O2‐ scavenger) did not change the effect of AII in control rings, but avoided the increased reactivity to AII in vessels from S60 rats. The endogenous activity of SOD was decreased by 45 ± 3%, while the generation of LOOH and GSH were increased by 41 ± 12% and 98 ± 3.9% in the aorta of S60 rats. A selective fluorescent probe revealed an increased ROS generation (up to 30%) in vessels from S60 rats after stimulation with AII. In conclusion, aortic rings from sepsis‐surviving rats display increased reactivity to AII, which involves augmented activity of ROCK and oxidative stress. Grant Funding Source: Supported by CAPES, CNPq, FAPESC
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