Recombinant human brain natriuretic peptide attenuates trauma-/haemorrhagic shock-induced acute lung injury through inhibiting oxidative stress and the NF-κB-dependent inflammatory/MMP-9 pathway

Recombinant human brain natriuretic peptide attenuates ischemic brain injury in mice by inhibiting oxidative stress and cell apoptosis via activation of PI3K/AKT/Nrf2/HO-1 pathway

Ischemic stroke followed by cerebral artery occlusion is a main cause of chronic disability worldwide. Recombinant human brain natriuretic peptide (rhBNP) has been reported to alleviate sepsis-induced cognitive dysfunction and brain I/R injury. However, the function and molecular mechanisms of rhBNP in ischemic brain injury have not been clarified. For establishment of an animal model of ischemic brain injury, C57BL/6 mice were treated with middle cerebral artery occlusion (MCAO) surgery for 1 h and reperfusion for 24 h. After subcutaneous injection of rhBNP into model mice, neurologic deficits were assessed by evaluating behavior of mice according to Longa scoring system, and TTC staining was utilized to determine the brain infarct size of mice. The levels of oxidative stress markers, superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA), were detected in hippocampal tissues of mice by corresponding kits. Cell apoptosis in hippocampus tissues was examined by TUNEL staining. Protein levels of antioxidant enzymes (HO-1 and NQO1) in cerebral cortex, apoptotic markers (Bax, Bcl-2, and cleaved caspase), and PI3K/AKT pathway-associated factors in hippocampus were tested by western blot analysis. The results revealed that injection of rhBNP decreased neurologic deficit scores, the percent of brain water content, and infarct volume. Additionally, rhBNP downregulated MDA level, upregulated the levels of SOD, CAT, and GSH in hippocampus of mice, and increased protein levels of HO-1 and NQO1 in the cortex. Cell apoptosis in hippocampus tissues of model mice was inhibited by rhBNP which was shown as the reduced TUNEL-positive cells, the decreased Bax, cleaved caspase-3, and cleaved caspase-9 protein levels, and the enhanced Bcl-2 protein level. In addition, rhBNP treatment activated the PI3K/AKT signaling pathway and upregulated the protein levels of HO-1 and NRF2. Overall, rhBNP activates the PI3K/AKT/HO-1/NRF2 pathway to attenuate ischemic brain injury in mice after MCAO by suppression of cell apoptosis and oxidative stress.

κ-Opioid Receptor Agonist U50448H Protects Against Acute Lung Injury in Rats with Cardiopulmonary Bypass via the CAP-NLRP3 Signaling Pathway

Objective. Acute lung injury (ALI) is one of the common and severe complications of cardiopulmonary bypass (CPB), which is the primary cause of death in intensive care units. Nevertheless, there is a lack of effective treatment for ALI secondary to CPB. κ-Opioid receptor (KOR) agonists have been demonstrated to improve lung function after pulmonary hypertension. However, its protective role has been barely reported in CPB-induced acute respiratory distress syndrome (ARDS). Therefore, this research focused on the protective effect of a KOR agonist U50448H on ARDS and investigated its potential relationship with the NOD-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome. Method. Forty-five rats were randomly allocated into Sham, CPB, and U50448 groups (n = 15 rats/group). After a CPB model was successfully established in rats, CPB rats were treated with the KOR agonist U50448H. The values of extravascular lung water (EVLW), alveolar-arterial oxygen tension difference (AaDO2), and respiratory index (RI) were examined, and the lung wet/dry (W/D) weight ratio was also calculated. Western blot (WB) was utilized to measure the expression of MMP-9, GSDMD-C, GSDMD-N, NLRP3, ASC, pro-Caspase-1, pro-IL-1β, and α7-nAChR. The immunofluorescence assay was performed for examining the expression of ROS, F480, iNOS, CD206, and α7-nAChR. Cell apoptosis was detected by the TUNEL assay. ELISA was used to test the level of LPS in serum and the level of MDA, GSH, SOD, TNF-α, IL-4, IL-6, IL-18, and IL-1β in lung tissues. Results. It was observed that the administration of U50448H significantly reduced EVLW values and LPS levels in the lung of rats. Meanwhile, U50448H increased AaDO2 values while decreasing RI values. Moreover, the administration of U50448H alleviated the pathological damage caused by ALI secondary to CPB. U50448H repressed ROS release and oxidative stress responses, as well as lowered LPS levels in plasma and MMP-9 expression in the lung of CPB rats. Furthermore, U50448H facilitated the shift of macrophage phenotype to M2. In addition, U50448H decreased the activity of the CAP-NLRP3 inflammasome and suppressed pyroptosis in pulmonary cells. Conclusion. The KOR agonist U50448H improved lung function and relieved lung injury in CPB rats, accompanied by diminished ROS and MMP-9 levels in lung tissues, promoted macrophage polarization from M1 to M2, and reduced NLRP3 inflammasome activities. These results indicated U50448H as a promising drug for the treatment of ALI secondary to CPB.

A novel protective role of sacubitril/valsartan in cyclophosphamide induced lung injury in rats: impact of miRNA-150-3p on NF-κB/MAPK signaling trajectories

Cyclophosphamide (CP) is a chemotherapeutic agent that induces oxidative stress causing multiple organ damage. Sacubitril/valsartan, is a combined formulation of neprilysin inhibitor (sacubitril) and angiotensin II receptor blocker (valsartan), that induces the protective effect of brain natriuretic peptide. The aim of the current study is to investigate the prophylactic impacts of sacubitril/valsartan versus valsartan against CP-induced lung toxicity in rats. Rats were assigned randomly into 6 groups; control; received corn oil (2 ml/kg/day; p.o. for 6 days), sacubitril/valsartan (30 mg/kg; p.o. for 6 days), valsartan (15 mg/kg; p.o. for 6 days), CP (200 mg/kg; i.p. on day 5), sacubitril/valsartan + CP (30 mg/kg; p.o. for 6 days, 200 mg/kg; i.p. single dose on day 5, respectively), valsartan + CP (15 mg/kg; p.o. for 6 days, 200 mg/kg; i.p. single dose on day 5, respectively). Both sacubitril/valsartan and valsartan produced a significant decrease in the inflammation and fibrosis markers in the BALF, in comparison with the CP group. Both sacubitril/valsartan and valsartan produced an apparent decrease in the relative genes expression of miR-150-3p and NF-κB, as well as a significant decrease in the relative expression of P38 and ERK1/2 MAPKs and an increase in the relative gene expression of Nrf-2, compared to CP group. Intriguingly, sacubitril/valsartan , showed subtle superiority in almost all investigated parameters, compared to valsartan. In conclusion, sacubitril/valsartan effectively abrogated the CP induced lung inflammation and fibrosis, providing a potential promising protection that could be linked to their ability to inhibit miR-150-3p via inhibition of NF-κB and MAPK signaling pathways.

Inflammation and Circulating Natriuretic Peptide Levels

BACKGROUND

NPs (natriuretic peptides) are cardiac-derived hormones that promote natriuresis, diuresis, and vasodilation. Preclinical evidence suggests that nonhemodynamic triggers for NP release exist, with a few studies implicating inflammatory stimuli. We examined the association between inflammation and NP levels in humans.

METHODS

The associations between inflammation and NP levels were examined in 3 independent studies. First, in 5481 MESA (Multi-Ethnic Study of Atherosclerosis) participants, the cross-sectional (exam 1) and longitudinal (exams 1 to 3) associations between circulating IL6 (interleukin-6) and NT-proBNP (N terminal pro B-type natriuretic peptide) levels were examined in multivariable-adjusted models. Second, in a prospective study of 115 healthy individuals, changes in NP levels were quantified following exposure to lipopolysaccharide as an inflammatory stimulus. Third, in 13 435 hospitalized patients, the association between acute inflammatory conditions and circulating NP levels was assessed using multivariable-adjusted models.

RESULTS

At the baseline MESA exam, each 1-unit higher natural log IL6 was associated with 16% higher NT-proBNP level ([95% CI, 10%-22%]; P=0.002). Each 1-unit higher baseline natural log IL6 level also associated with 6% higher NT-proBNP level ([95% CI, 1%-11%]; P=0.02) at 4-year follow-up. In the lipopolysaccharide study, median NT-proBNP levels rose from 21 pg/mL pre-lipopolysaccharide to 54 pg/mL post-lipopolysaccharide, P<0.001. In the hospitalized patient study, acute inflammatory conditions were associated with 36% higher NP levels ([95% CI, 17%-60%]; P<0.001).

CONCLUSIONS

Inflammation appears to be associated with NP release. Interpretation of NP levels should therefore take into account inflammatory conditions.

NF-κB mediates early blood-brain barrier disruption in a rat model of traumatic shock

BACKGROUND

Blood-brain barrier (BBB) disruption is associated with a large number of central nervous system and systemic disorders. The aim of the present study was to investigate the dynamic change of BBB changes during traumatic shock and resuscitation as well as the mechanisms involved.

METHODS

The experiments were performed on male Sprague-Dawley rats anesthetized with pentobarbital sodium. To produce traumatic shock, the rats were subjected to bilateral femoral traumatic fracture and blood withdrawal from the femoral artery to decrease mean arterial pressure (MAP) to 35 mm Hg. Hypovolemic status (at a MAP of 35 to 40 mm Hg) was sustained for 1 hour followed by fluid resuscitation with shed blood and 20 mL/kg of lactated Ringer's solution.

RESULTS

The rats were sacrificed at 1 hour, 2 hours, or 6 hours after fluid resuscitation. Blood-brain barrier permeability studies showed that traumatic shock significantly increased brain water contents and sodium fluorescein leakage, which was aggravated by fluid resuscitation. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analyses revealed that Na-K-Cl cotransporter-1 and vascular endothelial growth factor (VEGF) expression were upregulated in cortical brain tissue of traumatic shock rats, and this change was accompanied by downregulation of occludin and claudin-5. Traumatic shock also significantly increased the protein levels of NF-κB-p65 subunit. Of note, administration of NF-κB inhibitor PDTC effectively attenuated augmentation of the above changes.

CONCLUSION

Our results suggest that traumatic shock is associated with early BBB disruption, and inhibition of NF-κB may be an effective therapeutic strategy in protecting the BBB under traumatic shock conditions.

The Protective Effect of rhBNP on Postresuscitation Myocardial Dysfunction in a Rat Cardiac Arrest Model

PURPOSE

We investigated the protective effects and the underlying mechanisms through which recombinant human brain natriuretic peptide (rhBNP) acts on postresuscitation myocardial dysfunction (PRMD) in the cardiac arrest (CA) model.

METHODS

Ventricular fibrillation was induced and untreated for 6 min. And the time of cardiopulmonary resuscitation was 8 min, after which defibrillation was attempted in this rat model. 24 Sprague Dawley rats (450-550g) were randomized into cardiopulmonary resuscitation (CPR) + rhBNP and CPR + placebo groups after restoration of spontaneous circulation (ROSC). rhBNP was infused at PR 30 min (loading dose: 1.5 µg/kg, 3 min; maintenance dose: 0.01 µg/kg, 3 min; maintenance dose: 0.01 α (TNF-α (TNF-α (TNF-κB (NF-κB (NF.

RESULTS

The administration of rhBNP attenuated the severity of PRMD and myocardial tissue injuries, with improvement of MAP (mean arterial blood pressure), ETCO2 (end-tidal CO2), serum level of NT-proBNP, EF, CO, and MPI values. The serum levels and protein expression levels in myocardial tissue of IL-6 and TNF-α (TNF-κB (NF.

CONCLUSION

Our research demonstrated that the administration of rhBNP attenuated the severity of PRMD and myocardial tissue injuries and increased the 24 h survival rate in this CA model. rhBNP administration also reduced the serum and myocardial tissue levels of IL-6 and TNF-α after ROSC, likely due to the suppression of the TLR4/NF-κB signaling pathway and the regulation of inflammatory mediator secretion.α (TNF-κB (NF.

Ligustrazin increases lung cell autophagy and ameliorates paraquat-induced pulmonary fibrosis by inhibiting PI3K/Akt/mTOR and hedgehog signalling via increasing miR-193a expression

Background

Reactive oxygen species (ROS) levels largely determine pulmonary fibrosis. Antioxidants have been found to ameliorate lung fibrosis after long-term paraquat (PQ) exposure. The effects of antioxidants, however, on the signalling pathways involved in PQ-induced lung fibrosis have not yet been investigated sufficiently. Here, we examined the impacts of ligustrazin on lung fibrosis, in particular ROS-related autophagy and pro-fibrotic signalling pathways, using a murine model of PQ-induced lung fibrosis.

Methods

We explored the effects of microRNA-193 (miR-193a) on Hedgehog (Hh) and PI3K/Akt/mTOR signalling and oxidative stress in lung tissues. Levels of miR-193a, protein kinase B (Akt), phosphoinositide 3-Kinase (PI3K), ceclin1, mammalian target of rapamycin (mTOR), sonic hedgehog (SHH), myosin-like Bcl2 interacting protein (LC3), smoothened (Smo), and glioma-associated oncogene-1 (Gli-1) mRNAs were determined with quantitative real-time PCR. Protein levels of PI3K, p-mTOR, p-Akt, SHH, beclin1, gGli-1, LC3, smo, transforming growth factor-β1 (TGF-β1), mothers against DPP homologue-2 (Smad2), connective tissue growth factor (CTGF), collagen I, collagen III, α-smooth muscle actin (α-SMA) nuclear factor erythroid 2p45-related factor-2 (Nrf2), and p-Smad2 were detected by western blotting. In addition, α-SMA, malondialdehyde, ROS, superoxide dismutase (SOD), oxidised and reduced glutathione, hydroxyproline, and overall collagen levels were identified in lung tissues using immunohistochemistry.

Results

Long-term PQ exposure blocked miR-193a expression, reduced PI3K/Akt/mTOR signalling, increased oxidative stress, inhibited autophagy, increased Hh signalling, and facilitated the formation of pulmonary fibrosis. Ligustrazin blocked PI3K/Akt/mTOR and Hh signalling as well as reduced oxidative stress via increasing miR-193a expression and autophagy, all of which reduced pulmonary fibrosis. These effects of ligustrazin were accompanied by reduced TGF-β1, CTGF, and Collagen I and III expression.

Conclusions

Ligustrazin blocked PQ-induced PI3K/Akt/mTOR and Hh signalling by increasing miR-193a expression, thereby attenuating PQ-induced lung fibrosis.

Brain Natriuretic Peptide-Regulated Expression of Inflammatory Cytokines in Lipopolysaccharide (LPS)-Activated Macrophages via NF-κB and Mitogen Activated Protein Kinase (MAPK) Pathways

Background

This study aimed to investigate the effects of recombinant human brain natriuretic peptide (rhBNP) on IL-6, TNF-α, and IL-10 secretion in LPS-activated RAW 264.7 cells and human peripheral blood mononuclear cells (PBMCs) in vitro and to explore the related signaling pathways of the regulation mechanisms of BNP in systemic inflammatory response syndrome (SIRS).

Material/Methods

MTT assay was used to evaluate the effects of rhBNP on cell viabilities. Lipopolysaccharide (LPS) was used to induce inflammation response. The whole study was divided into 8 groups: Control, low, middle, and high concentrations of rhBNP, LPS, LPS with low, middle, and high concentrations of rhBNP. Levels of IL-6, TNF-α, and IL-10 were evaluated using the Cytometric Bead Array Kit and RT-PCR assay. Western blotting was used to test the effects of rhBNP on inflammation-related NF-κB and MAPK pathways.

Results

Except for the concentrations ≥1.6 ng/mL, all concentrations of rhBNP showed little effect on cell viabilities of RAW264.7 cells and PBMCs after 24 h and 48 h, suggesting a weak cytotoxicity to cells. Expression of IL-6 and TNF-α significantly increased and expression of IL-10 significantly decreased at protein and mRNA levels after LPS treatment, and these effects were strongly inhibited in a dose-dependent manner by pretreatment of rhBNP. Similarly, the LPS-induced increase of NF-κB and MAPK pathway phosphorylation levels were also significantly inhibited by rhBNP.

Conclusions

rhBNP can regulate expression of IL-6, TNF-α, and IL-10 in LPS-activated RAW 264.7 cells and PBMCs through inhibiting NF-κB and MAPK pathways. These results may reveal potential causes of the increase of BNP in SIRS and may provide an experimental basis for treatment of SIRS.

Cardiomyokines from the heart

The heart is regarded as an endocrine organ as well as a pump for circulation, since atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were discovered in cardiomyocytes to be secreted as hormones. Both ANP and BNP bind to their receptors expressed on remote organs, such as kidneys and blood vessels; therefore, the heart controls the circulation by pumping blood and by secreting endocrine peptides. Cardiomyocytes secrete other peptides besides natriuretic peptides. Although most of such cardiomyocyte-derived peptides act on the heart in autocrine/paracrine fashions, several peptides target remote organs. In this review, to overview current knowledge of endocrine properties of the heart, we focus on cardiomyocyte-derived peptides (cardiomyokines) that act on the remote organs as well as the heart. Cardiomyokines act on remote organs to regulate cardiovascular homeostasis, systemic metabolism, and inflammation. Therefore, through its endocrine function, the heart can maintain physiological conditions and prevent organ damage under pathological conditions.

Establishment and evaluation of rat trauma hemorrhagic liver injury model

Trauma hemorrhagic shock is a common and critical disease, which induces multiple organ failure, especially of the liver, when combined with fracture. However, no effective trauma hemorrhagic liver injury model that mimics the real-life condition has been developed so far. This study aims to develop an effective trauma hemorrhagic liver injury model based on a fracture and hemorrhage approach. The levels of the following proteins were determined by the enzyme-linked immunosorbent assay (ELISA) in our fracture and hemorrhage-based model system: serum alanine transaminase (ALT), aspartate aminotransferase (AST), inflammatory cytokines such as interleukin-1β, interleukin-6, and tumor necrosis factor-α, chemokines such as C-C motif ligand 2, C-C motif ligand 5, C-C motif ligand 13, and C-X-C motif ligand 2. Pathological changes in the liver and the numbers of CD45⁺ cells and polymorphic nuclear neutrophils (PMNs) in the liver parenchyma were analyzed by hematoxylin-eosin staining, periodic acid-Schiff staining, and flow cytometry, respectively. As expected, the serum levels of ALT and AST increased significantly with trauma time and peaked at 16 hrs post-trauma. Similarly, the levels of the inflammatory cytokines also increased significantly with trauma time, and peaked after 8 hrs or 16 hrs of trauma. Analysis of hepatic morphology at the time-point when the trauma was inflicted and at later time-points post-trauma, revealed invasion of inflammatory cells, formation of hyperchromatic nuclei, and presence of loose and irregular acinus and vacuolus; the phenotype was most severe at 16 hrs post-trauma. The number of CD45⁺ cells and PMNs increased significantly with trauma time and peaked after 16 hrs of trauma. These observations indicated that the trauma hemorrhagic liver injury model was successfully established and that it could provide an effective system to study the mechanisms of trauma hemorrhagic liver injury.

Perioperative "remote" acute lung injury: recent update

Perioperative acute lung injury (ALI) is a syndrome characterised by hypoxia and chest radiograph changes. It is a serious post-operative complication, associated with considerable mortality and morbidity. In addition to mechanical ventilation, remote organ insult could also trigger systemic responses which induce ALI. Currently, there are limited treatment options available beyond conservative respiratory support. However, increasing understanding of the pathophysiology of ALI and the biochemical pathways involved will aid the development of novel treatments and help to improve patient outcome as well as to reduce cost to the health service. In this review we will discuss the epidemiology of peri-operative ALI; the cellular and molecular mechanisms involved on the pathological process; the clinical considerations in preventing and managing perioperative ALI and the potential future treatment options.

[Pathophysiology of hemorragic shock]

This review addresses the pathophysiology of hemorrhagic shock, a condition produced by rapid and significant loss of intravascular volume, which may lead to hemodynamic instability, decreases in oxygen delivery, decreased tissue perfusion, cellular hypoxia, organ damage, and death. The initial neuroendocrine response is mainly a sympathetic activation. Haemorrhagic shock is associated altered microcirculatory permeability and visceral injury. It is also responsible for a complex inflammatory response associated with hemostasis alteration.

Protective role of nuclear factor erythroid 2-related factor 2 in the hemorrhagic shock-induced inflammatory response

Hemorrhagic shock (HS) following trauma or major surgery significantly contributes to mortality. However, the mechanisms through which HS activates the inflammatory response are not yet fully understood. Nuclear factor-erythroid 2 (NF-E2) p45-related factor-2 (Nrf2), a bZIP transcription factor, is a master regulator of robust cytoprotective defenses. The present study investigated the role of Nrf2 in the pathophysiology of HS. Nrf2 expression in peripheral leukocytes obtained from patients with surgery-associated hemorrhage subjected to resuscitation treatment (termed HS patients) or healthy donors was examined by RT-qPCR. A marked increase in Nrf2 expression was detected in the leukocytes obtained from the HS patients, which indicates a correlation between Nrf2 expression and the development of HS. Wild-type (WT; Nrf2^+/+) and Nrf2-deficient [Nrf2^−/− or Nrf2-knockout (KO)] mice were subjected to surgery to induce HS. Systemic inflammation was significantly elevated in the Nrf2-KO mice compared with the WT mice following HS, as assessed by an increase in serum cytokine levels [interleukin (IL)-6, tumor necrosis factor (TNF)-α and IL-1β], as well as high-mobility group box 1 protein (HMGB1) expression. The Nrf2-KO mice exhibited more severe lung and liver injury following HS as evidenced by increased tissue damage, increased myeloperoxidase (MPO) activity and the increased production of pro-inflammatory cytokines. Additionally, Nrf2 deficiency augmented cytokine production induced by the exposure of peritoneal mouse macrophages to lipopolysaccha-ride (LPS) following HS. Taken together, these results suggest that Nrf2 is a critical host factor which limits immune dysregulation and organ injury following HS.