Protective effects of growth hormone - releasing hormone antagonists in the lungs of septic mice.

Growth hormone-releasing hormone antagonists (GHRHAnt) have been associated with antitumor and antioxidative activities. The present study investigates for the first time the effects of those compounds towards pro-inflammatory cytokine expression in a murine model of cecal ligation and puncture (CLP) - induced sepsis. The results indicate that GHRHAnt JV-1-36 significantly suppressed IL-1α, IL-6, and pSTAT3 activation in septic lungs. Moreover, GHRHAnt treatment reduced bronchoalveolar lavage fluid (BALF) protein concentration, suggesting a protective effect of that compound in sepsis-induced lung edema. Based on those findings, it is suggested that GHRHAnt may represent an exciting new therapeutic possibility in sepsis-induced endotoxemia and lung injury.

Protective Activities of Growth Hormone-Releasing Hormone Antagonists against Toxin-Induced Endothelial Injury.

GHRH regulates the secretion of GH from the anterior pituitary gland, previously associated with cancer progression and inflammation. An emerging body of evidence suggests that GHRHAnt support endothelial barrier function, but the mechanisms mediating these events are not completely understood. In the present study, it is demonstrated that the GHRHAnt JV-1-36 counteracts barrier dysfunction due to LPS or LTA treatment in HUVECs, utilizing the Dextran-FITC assay. Moreover, it is shown in BPAECs that these bacterial toxins increase ROS generation, and that this effect is counteracted by JV-1-36, which reinstates the redox balance. The possible involvement of NEK2 in the beneficial activities of GHRHAnt in IFN-γ- and LPS-triggered hyperpermeability was also assessed, since that kinase is involved in inflammatory responses. NEK2 was increased in the inflamed cells, and JV-1-36 counteracted those endothelial events. Our data support the beneficial effects of GHRHAnt in toxin-induced endothelial injury.

NEK-mediated barrier regulation.

Endothelial dysfunction has been associated with devastating outcomes which can eventually lead to permanent disability and death. Elucidation of the meticulously devised network orchestrating endothelial responses, provides information to develop new therapies towards endothelial-related disorders. NEK kinases - which have been involved in the development of human disease - promote vascular leak; suggesting the possibility that their inhibition may ameliorate medical conditions related to barrier derangement.

Involvement of NEK2 and NEK9 in LPS - induced endothelial barrier dysfunction.

Endothelial hyperpermeability is the hallmark of severe lung injury, including acute respiratory distress syndrome. Despite the fact that Never In Mitosis A (NIMA)-related kinase 2 (NEK2) and NEK9 mediate fundamental cellular processes, our knowledge on their role in barrier function is limited. Herein we show that NEK2 and NEK9 inhibition suppresses LPS-induced paracellular hyperpermeability and myosin light chain 2 activation in endothelial cells. Moreover, the expression levels of both kinases were elevated in inflamed mouse lungs. Based on those findings, we raise the possibility that NEK2 and NEK9 may serve as novel therapeutic targets in lung inflammatory disease.

Growth hormone-releasing hormone antagonists counteract interferon-γ - induced barrier dysfunction in bovine and human endothelial cells.

GHRH regulates the secretion of GH from the anterior pituitary gland. An emerging body of evidence suggests that the activities of that neuropeptide are not limited to the GH/IGF-I axis, but they expand towards the mediation of inflammatory processes. GHRHAnt were developed to oppose the activities of GHRH in malignancies, and have been associated with strong anti-inflammatory and anti-oxidative effects in a diverse variety of tissues, including the lungs. In the present study we report that GHRHAnt oppose interferon-γ - induced paracellular hyperpermeability and reactive oxygen species generation in bovine and human pulmonary endothelial cells; and suppress interferon-γ - triggered STAT3, cofilin and ERK1/2 activation. Our observations substantiate previous findings on the protective effects of GHRHAnt in endothelial inflammation and barrier break-down.

Pneumonic Injury and Repair: A Synopsis.

It has been my great pleasure to have joined forces with Pharmaceutical's editorial team in order to organize and publish a Special Issue on "Lung Injury and Repair" [...].

Ceapin-A7 potentiates lipopolysaccharide-induced endothelial injury.

Barrier dysfunction is the hallmark of severe lung injury, including acute respiratory distress syndrome. Efficient medical countermeasures to counteract endothelial hyperpermeability do not exist, hence the mortality rates of disorders related to barrier abnormalities are unacceptable high. The unfolded protein response is a highly conserved mechanism, which aims to support the cells against endoplasmic reticulum stress, and ATF6 is a protein sensor that triggers its activation. In the current study, we investigate the effects of ATF6 suppression in LPS-induced endothelial inflammation. Our observations suggest that Ceapin-A7, which is an ATF6 suppressor, potentiates LPS-induced STAT3 and JAK2 activation. Hence ATF6 activation may serve as a new therapeutic possibility toward diseases related to barrier dysfunction.

Unfolded protein response suppression potentiates LPS-induced barrier dysfunction and inflammation in bovine pulmonary artery endothelial cells.

The development of novel strategies to counteract diseases related to barrier dysfunction is a priority, since sepsis and acute respiratory distress syndrome are still associated with high mortality rates. In the present study, we focus on the effects of the unfolded protein response suppressor (UPR) 4-Phenylbutyrate (4-PBA) in Lipopolysaccharides (LPS)-induced endothelial injury, to investigate the effects of that compound in the corresponding damage. 4-PBA suppressed binding immunoglobulin protein (BiP) - a UPR activation marker - and potentiated LPS - induced signal transducer and activator of transcription 3 (STAT3) and extracellular signal­regulated protein kinase (ERK) 1/2 activation. In addition to those effects, 4-PBA enhanced paracellular hyperpermeability in inflamed bovine pulmonary endothelial cells, and did not affect cell viability in moderate concentrations. Our observations suggest that UPR suppression due to 4-PBA augments LPS-induced endothelial injury, as well as the corresponding barrier disruption.

Growth hormone-releasing hormone antagonists counteract hydrogen peroxide - induced paracellular hyperpermeability in endothelial cells.

Growth Hormone-Releasing Hormone (GHRH) is a hypothalamic peptide which regulates the release of Growth Hormone from the anterior pituitary gland, and has been involved in inflammatory processes. On the other hand, GHRH antagonists (GHRHAnt) were developed to counteract those effects. Herein we demonstrate for the first time that GHRHAnt can suppress hydrogen peroxide (H2O2) - induced paracellular hyperpermeability in bovine pulmonary artery endothelial cells. Increased production of reactive oxygen species (ROS) and barrier dysfunction have been associated with the development of potentially lethal disorders, including sepsis and acute respiratory distress syndrome (ARDS). Our study supports the protective actions of GHRHAnt in the impaired endothelium, and suggests that those compounds represent an exciting therapeutic possibility towards lung inflammatory disease.

Growth hormone-releasing hormone antagonists protect against hydrochloric acid-induced endothelial injury in vitro.

Growth hormone-releasing hormone (GHRH) regulates the synthesis of growth hormone from the anterior pituitary gland, and it is involved in inflammatory responses. On the other hand, GHRH antagonists (GHRHAnt) exhibit the opposite effects, resulting in endothelial barrier enhancement. Exposure to hydrochloric acid (HCL) is associated with acute and chronic lung injury. In this study, we investigate the effects of GHRHAnt in HCL-induced endothelial barrier dysfunction, utilizing commercially available bovine pulmonary artery endothelial cells (BPAEC). Cell viability was measured by utilizing 3-(4,5-dimethylthiazol2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay. Moreover, fluorescein isothiocyanate (FITC)-dextran was used to assess barrier function. Our observations suggest that GHRHAnt exert protective effects against HCL-induced endothelial breakdown, since those peptides counteract HCL-triggered paracellular hyperpermeability. Based on those findings, we propose that GHRHAnt represent a new therapeutic approach towards HCL-induced endothelial injury.

Protective effects of GHRH antagonists against hydrogen peroxide-induced lung endothelial barrier disruption.

PURPOSE: Growth hormone-releasing hormone (GHRH) is a hypothalamic hormone, which regulates growth hormone release from the anterior pituitary gland. GHRH antagonists (GHRHAnt) are anticancer agents, which also exert robust anti-inflammatory activities in malignancies. GHRHAnt exhibit anti-oxidative and anti-inflammatory effects in vascular endothelial cells, indicating their potential use against disorders related to barrier dysfunction (e.g. sepsis). Herein, we aim to investigate the effects of GHRHAnt against lung endothelial hyperpermeability. METHODS: The in vitro effects of GHRHAnt in H2O2-induced endothelial barrier dysfunction were investigated in bovine pulmonary artery endothelial cells (BPAEC). Electric cell-substrate impedance sensing (ECIS) was utilized to measure transendothelial resistance, an indicator of barrier function. RESULTS: Our results demonstrate that GHRHAnt protect against H2O2-induced endothelial barrier disruption via P53 and cofilin modulation. Both proteins are crucial modulators of vascular integrity. Moreover, GHRHAnt prevent H2O2 - induced decrease in transendothelial resistance. CONCLUSIONS: GHRHAnt represent a promising therapeutic intervention towards diseases related to lung endothelial hyperpermeability, such as acute respiratory distress syndrome - related or not to COVID-19 - and sepsis. Targeted medicine for those potentially lethal disorders does not exist.

Growth Hormone-Releasing Hormone in Endothelial Inflammation.

The discovery of hypothalamic hormones propelled exciting advances in pharmacotherapy and improved life quality worldwide. Growth hormone-releasing hormone (GHRH) is a crucial element in homeostasis maintenance, and regulates the release of growth hormone from the anterior pituitary gland. Accumulating evidence suggests that this neuropeptide can also promote malignancies, as well as inflammation. Our review is focused on the role of that 44 - amino acid peptide (GHRH) and its antagonists in inflammation and vascular function, summarizing recent findings in the corresponding field. Preclinical studies demonstrate the protective role of GHRH antagonists against endothelial barrier dysfunction, suggesting that the development of those peptides may lead to new therapies against pathologies related to vascular remodeling (eg, sepsis, acute respiratory distress syndrome). Targeted therapies for those diseases do not exist.

Growth Hormone-Releasing Hormone Antagonist JV-1-36 Suppresses Reactive Oxygen Species Generation in A549 Lung Cancer Cells.

Growth hormone-releasing hormone (GHRH) and its receptors are expressed in a variety of human cancers, and have been involved in malignancies. GHRH antagonists (GHRHAnt) were developed to suppress tumor progression and metastasis. Previous studies demonstrate the involvement of reactive oxygen species (ROS) in cancer progression. Herein, we investigate the effect of a commercially available GHRH antagonist, namely JV-1-36, in the redox status of the A549 human cancer cell line. Our results suggest that this peptide significantly reduces ROS production in those cells in a time-dependent manner and counteracts H2O2-induced ROS. Our study supports the anti-oxidative effects of JV-1-36 and contributes in our knowledge towards the in vitro effects of GHRHAnt in cancers.

Activating transcription factor 6 protects against endothelial barrier dysfunction.

BACKGROUND: Endothelial hyperpermeability is associated with sepsis and acute respiratory distress syndrome (ARDS). The identification of molecular pathways involved in barrier dysfunction; may reveal promising therapeutic targets to combat ARDS. Unfolded protein response (UPR) is a highly conserved molecular pathway, which ameliorates endoplasmic reticulum stress. The present work focuses on the effects of ATF6, which is a UPR sensor, in lipopolysaccharides (LPS)-induced endothelial hyperpermeability. METHODS: The in vitro effects of AA147 and Ceapin-A7 in LPS-induced endothelial barrier dysfunction were investigated in bovine pulmonary artery endothelial cells (BPAEC). Small interfering (si) RNA was utilized to "silence" ATF6, and electric cell-substrate impedance sensing (ECIS) measured transendothelial resistance. Fluorescein isothiocyanate (FITC)-dextran assay was utilized to assess paracellular permeability. Protein expression levels were evaluated with Western blotting, and cell viability with MTT assay. RESULTS: We demonstrated that AA147 prevents LPS-induced barrier disruption by counteracting Cofilin and myosin light chain 2 (MLC2) activation, as well as VE-Cadherin phosphorylation. Moreover, this ATF6 inducer opposed LPS-triggered decrease in transendothelial resistance (TEER), as well as LPS-induced paracellular hyperpermeability. On the other hand, ATF6 suppression due to Ceapin-A7 or small interfering RNA exerted the opposite effects, and potentiated LPS-induced endothelial barrier disruption. Moderate concentrations of both ATF6 modulators did not affect cell viability. CONCLUSIONS: ATF6 activation protects against endothelial barrier function, suggesting that this UPR sensor may serve as a therapeutic target for sepsis and ARDS.

P53 in endothelial function and unfolded protein response regulation.

Vascular barrier dysfunction due to endothelial hyperpermeability has been associated with the pathophysiology of sepsis and severe lung injury, which may inflict acute respiratory distress syndrome (ARDS). Our group is focused on the mechanisms operating towards the regulation of endothelial permeability, to contribute in the development of efficient and targeted countermeasures against ARDS. Unfortunately, the number of ARDS-related deaths in the intensive care units has dramatically increased during the COVID-19 era. The findings described herein inform the corresponding scientific and medical community on the relation of P53 and stress responses in barrier function.

Unfolded protein response in endothelial injury.

Endothelial barrier dysfunction is associated with sepsis and lung injury, both direct and indirect. We discuss the involvement of unfolded protein response in the protective effects of heat shock protein 90 inhibitors and growth hormone releasing hormone antagonists in the vascular barrier, to reveal new possibilities in acute respiratory distress syndrome treatment.

Hsp90 inhibition protects brain endothelial cells against LPS-induced injury.

Dysfunction of the blood-brain barrier (BBB) endothelium increases infiltration of lymphocytes and innate immune cells in the brain, leading to the development of neurological disorders. Heat shock protein 90 (Hsp90) inhibitors are anti-inflammatory agents and P53 inducers, which reduce the production of reactive oxygen species (ROS) in a diverse variety of human tissues. In this study, we investigate the effects of those compounds in LPS-induced brain endothelial inflammation, by utilizing human cerebral microvascular endothelial cells (hCMEC/D3). Our results suggest that Hsp90 inhibitors suppress inflammation by inhibiting the LPS-induced signal transducer and activator of transcription 3 (STAT3); and P38 activation. Moreover, those compounds reduce the P53 suppressors murine double minute 2 (MDM2) and murine double minute 4 (MDM4). Immunoglobulin heavy chain binding protein/glucose-regulated protein 78 (BiP/Grp78)-a key element of endothelial barrier integrity-was also increased by Hsp90 inhibition. Hence, we conclude that application of Hsp90 inhibitors in diseases related to BBB dysfunction may deliver a novel therapeutic possibility in the affected population.