Norepinephrine induces alveolar epithelial apoptosis mediated by alpha-, beta-, and angiotensin receptor activation

α 2 -ADRENORECEPTOR ANTAGONIST AMELIORATES SEPSIS-ASSOCIATED PULMONARY FIBROSIS BY SUPPRESSING NOREPINEPHRINE-MEDIATED FIBROBLAST DIFFERENTIATION VIA INHIBITING PKC ACTIVATION

ABSTRACT

Pulmonary fibrosis is an important factor affecting the prognosis of severe septic patients with acute lung injury. The objective of this study was to explore the effect of norepinephrine (NE) and α 2 -adrenoreceptor (AR) on sepsis-associated pulmonary fibrosis and the mechanism underlying these effects. We found pulmonary fibrotic changes, and increased NE production and α 2A -AR expression in the pulmonary tissue of mice subjected to cecal ligation and puncture surgery. Reserpine and yohimbine alleviated pulmonary fibrosis in mice with sepsis by exhausting NE derived from the lung's adrenergic nerve and blocking α 2 -AR, respectively. There was no significant difference in the expression of the three α 1 -AR subtypes. The effect of NE on promoting pulmonary fibroblast differentiation in vitro was suppressed by yohimbine. Both the protein and mRNA expression levels of α 2A -AR were increased in pulmonary fibroblasts treated with LPS. Clonidine, a selective α 2 -AR agonist, enhanced LPS-induced differentiation in pulmonary fibroblasts, as indicated by the increase in α-smooth muscle actin and collagen I/III, which was mitigated by inhibiting PKC and p38. Further in vivo results indicated that yohimbine alleviated pulmonary fibrosis and inhibited the phosphorylation of PKC, p38, and Smad2/3 in lung tissue of mice exposed to LPS for 4 weeks. Clonidine showed the opposite effect to yohimbine, which aggravated LPS-induced pulmonary fibrosis. These findings demonstrated that the sepsis-induced increase in NE promoted fibroblast differentiation via activating α 2 -AR. Blockage of α 2 -AR effectively ameliorated sepsis-associated pulmonary fibrosis by abolishing NE-induced lung fibroblast differentiation and inhibiting the PKC-p38-Smad2/3 pathway.

Norepinephrine promotes neuronal apoptosis of hippocampal HT22 cells by up-regulating the expression of long non-coding RNA MALAT1

Stress is ever present in our modern, performance-oriented and demanding society, which causes adverse stress reactions of the body and affects health seriously. Chronic stress has been recognized as a significant risk factor leading to cognitive impairment, but the underlying mechanism is far from fully understood. Norepinephrine (NE), a pivotal stress-induced hormone, has been found to induce cell apoptosis. However, the function and the key downstream mediator of NE on the regulation of hippocampal neurons still need further exploration. In this study, we explored the role of NE in neuronal apoptosis and its association with MALAT1. Flow cytometry assay and automated western bot assay were carried out to evaluate the cell apoptosis. The data showed that the rate of apoptosis rate and the levels of apoptotic proteins (cleaved-Caspase3 and cleaved-PARP) were significantly increased in HT22 cells after a high dose of NE treatment, suggesting a facilitative role of NE on hippocampal neuronal apoptosis. Besides, a high level of NE up-regulated the expression of MALAT1 in HT22 cells. Then, a lentivirus expressing MALAT1 shRNA was constructed to investigate the role of MALAT1 in cell apoptosis and the results revealed that MALAT1 depletion decreased the cell apoptosis. Moreover, the knockdown of MALAT1 abolished the discrepancy in apoptosis between NE-treated cells and control cells. In conclusion, a high level of the stress-induced hormone NE promoted apoptosis of hippocampal neurons by elevating the expression of MALAT1. Our findings provide new experimental data supporting the epigenetic mechanisms in the regulation of stress response and may provide a potential therapeutic target for stress-related cognition dysfunction.

Neuroimmune Interactions in the Gut and Their Significance for Intestinal Immunity

Inflammatory bowel diseases (IBD) have a complex, multifactorial pathophysiology with an unmet need for effective treatment. This calls for novel strategies to improve disease outcome and quality of life for patients. Increasing evidence suggests that autonomic nerves and neurotransmitters, as well as neuropeptides, modulate the intestinal immune system, and thereby regulate the intestinal inflammatory processes. Although the autonomic nervous system is classically divided in a sympathetic and parasympathetic branch, both play a pivotal role in the crosstalk with the immune system, with the enteric nervous system acting as a potential interface. Pilot clinical trials that employ vagus nerve stimulation to reduce inflammation are met with promising results. In this paper, we review current knowledge on the innervation of the gut, the potential of cholinergic and adrenergic systems to modulate intestinal immunity, and comment on ongoing developments in clinical trials.

Effect of lipopolysaccharide on angiotensin II type 1 receptor expression and function in human pulmonary microvascular endothelial cells

Lipopolysaccharides (LPSs) are an important initiation factor in acute respiratory distress syndrome. The aim of the present study was to investigate the effect of LPSs on the regulation of angiotensin II (Ang II) receptors in human pulmonary microvascular endothelial cells (HPMECs). HPMECs were treated with 0, 50, 100 or 200 ng/ml LPS and incubated for 4, 8, 12 or 16 h. The expression of Ang II type 1 receptor (AT1R) and Ang II type 2 receptor (AT2R) was determined using reverse transcription‑polymerase chain reaction and western blot analysis. The affinity to Ang II was measured using a radioligand binding assay. No AT2R expression was detected with or without LPS administration in HPMECs, and LPS treatment increased the expression level of AT1R. A time‑dependent increase of AT1R transcription was observed in the 50 ng/ml group, while in the 100 and 200 ng/ml groups, the AT1R mRNA levels reached peak values at 4 h and remained unchanged. The protein level of AT1R increased significantly in a dose‑dependent manner for each incubation time period. A time‑dependent increase in the protein level was observed in the 50 and 100 ng/ml groups. As for the 200 ng/ml group, the level of AT1R reached a peak value at 8 h. Maximal binding (Bmax) significantly increased following LPS treatment and Bmax of the 50 ng/ml group exhibited a time‑dependent increase. The Bmax of the 100 and 200 ng/ml groups reached peak values at 12 and 8 h, respectively, and decreased thereafter. The dissociation constant remained unchanged following LPS treatment. Thus, treatment with LPS increased AT1R expression and its Bmax to Ang II in HPMECs, however, did not alter the affinity of AT1R to Ang II.

The effects of salbutamol on epithelial ion channels depend on the etiology of acute respiratory distress syndrome but not the route of administration

Introduction

We investigated the effects of intravenous and intratracheal administration of salbutamol on lung morphology and function, expression of ion channels, aquaporin, and markers of inflammation, apoptosis, and alveolar epithelial/endothelial cell damage in experimental pulmonary (p) and extrapulmonary (exp) mild acute respiratory distress syndrome (ARDS).

Methods

In this prospective randomized controlled experimental study, 56 male Wistar rats were randomly assigned to mild ARDS induced by either intratracheal (n = 28, ARDSp) or intraperitoneal (n = 28, ARDSexp) administration of E. coli lipopolysaccharide. Four animals with no lung injury served as controls (NI). After 24 hours, animals were anesthetized, mechanically ventilated in pressure-controlled mode with low tidal volume (6 mL/kg), and randomly assigned to receive salbutamol (SALB) or saline 0.9% (CTRL), intravenously (i.v., 10 μg/kg/h) or intratracheally (bolus, 25 μg). Salbutamol doses were targeted at an increase of ≈ 20% in heart rate. Hemodynamics, lung mechanics, and arterial blood gases were measured before and after (at 30 and 60 min) salbutamol administration. At the end of the experiment, lungs were extracted for analysis of lung histology and molecular biology analysis. Values are expressed as mean ± standard deviation, and fold changes relative to NI, CTRL vs. SALB.

Results

The gene expression of ion channels and aquaporin was increased in mild ARDSp, but not ARDSexp. In ARDSp, intravenous salbutamol resulted in higher gene expression of alveolar epithelial sodium channel (0.20 ± 0.07 vs. 0.68 ± 0.24, p < 0.001), aquaporin-1 (0.44 ± 0.09 vs. 0.96 ± 0.12, p < 0.001) aquaporin-3 (0.31 ± 0.12 vs. 0.93 ± 0.20, p < 0.001), and Na-K-ATPase-α (0.39 ± 0.08 vs. 0.92 ± 0.12, p < 0.001), whereas intratracheal salbutamol increased the gene expression of aquaporin-1 (0.46 ± 0.11 vs. 0.92 ± 0.06, p < 0.001) and Na-K-ATPase-α (0.32 ± 0.07 vs. 0.58 ± 0.15, p < 0.001). In ARDSexp, the gene expression of ion channels and aquaporin was not influenced by salbutamol. Morphological and functional variables and edema formation were not affected by salbutamol in any of the ARDS groups, regardless of the route of administration.

Conclusion

Salbutamol administration increased the expression of alveolar epithelial ion channels and aquaporin in mild ARDSp, but not ARDSexp, with no effects on lung morphology and function or edema formation. These results may contribute to explain the negative effects of β2-agonists on clinical outcome in ARDS.

Preclinical modeling of a phase 0 clinical trial: qualification of a pharmacodynamic assay of poly (ADP-ribose) polymerase in tumor biopsies of mouse xenografts

PURPOSE

The National Cancer Institute has completed a first-in-human clinical pharmacodynamic trial of the targeted agent ABT-888, a poly (ADP-ribose) polymerase (PARP) inhibitor, under the auspices of the U.S. Food and Drug Administration's Exploratory Investigational New Drug Application. Performance of the study design, needle biopsy procedure, and validated pharmacodynamic assay were evaluated in human tumor xenograft models.

EXPERIMENTAL DESIGN

A validated ELISA was used to quantify PAR, a product of the PARP 1/2 enzyme activity. Sampling variability from tumor heterogeneity was determined by comparing PAR content in multiple tumors, and in different areas of the same tumor in a particular animal, collected under anesthesia by needle biopsy or resection before and after administration of nontoxic doses of ABT-888. The degree of PARP inhibition following single-dose treatment was evaluated in the time frame anticipated for biopsy in humans.

RESULTS

Sampling variability around the mean (approximately 50%) for untreated and vehicle-treated animals was random and due to specimen heterogeneity. PAR levels in initial and repeat tumor biopsies, separated by 1 week, were not altered by the stress induced by daily handling of the animals. A single ABT-888 dose (3 or 12.5 mg/kg) reduced intratumor PAR levels by >95%. ABT-888 (1.56-25 mg/kg) significantly decreased PAR levels at 2 h post-dosing.

CONCLUSION

The detailed methodologies developed for this study facilitated the design of a phase 0, first-in-human clinical trial of ABT-888 and could serve as a model for developing proof-of-principle clinical trials of molecularly targeted anticancer agents.

Neurotransmission and cancer: implications for prevention and therapy

Published evidence compiled in this review supports the hypothesis that the development, progression, and responsiveness to prevention and therapy of the most common human cancers is strongly influenced, if not entirely orchestrated, by an imbalance in stimulatory and inhibitory neurotransmission. The neurotransmitters acetylcholine, adrenaline, and noradrenaline of the autonomic nervous system act as powerful upstream regulators that orchestrate numerous cell and tissue functions, by releasing growth factors, angiogenesis factors and metastasis factors, arachidonic acid, proinflammatory cytokines, and local neurotransmitters from cancer cells and their microenvironment. In addition, they modulate proliferation, apoptosis, angiogenesis, and metastasis of cancer directly by intracellular signaling downstream of neurotransmitter receptors. Nicotine and the tobacco-specific nitrosamines have the documented ability to hyperstimulate neurotransmission by both branches of the autonomic nervous system. The expression and function of these neurotransmitter pathways are cell type specific. Lifestyle, diet, diseases, stress, and pharmacological treatments modulate the expression and responsiveness of neurotransmitter pathways. Current preclinical testing systems fail to incorporate the modulating effects of neurotransmission on the responsiveness to anticancer agents and should be amended accordingly. The neurotransmitter gamma-aminobutyric acid has a strong inhibitory function on sympathicus-driven cancers whereas stimulators of cyclic adenosine monophosphate/protein kinase A signaling have strong inhibitory function on parasympathicus-driven cancers. Marker-guided restoration of the physiological balance in stimulatory and inhibitory neurotransmission represents a promising and hitherto neglected strategy for the prevention and therapy of neurotransmitter-responsive cancers.

Preponderance of sensory versus sympathetic nerve fibers and increased cellularity in the infrapatellar fat pad in anterior knee pain patients after primary arthroplasty

Sensory nerve fibers transmit pain perception and secrete pro-inflammatory substance P (SP). Sympathetic nerve fibers secrete anti-inflammatory norepinephrine and endogenous opioids, which inhibit pain perception in a bidirectional crosstalk with sensory fibers. In patients with anterior knee pain after primary arthroplasty of the knee (AKP), this study investigated in parallel the innervation of the infrapatellar fat pad by sensory and sympathetic nerve fibers. A total of 32 patients with osteoarthritis (OA) of the knee (n = 10), AKP after primary knee joint replacement (n = 7), and OA of the hip (n = 15) were included. Sensory nerve fibers were semiquantitatively detected by immunohistochemistry against SP, and sympathetic nerve fibers were stained with an antibody against tyrosine hydroxylase. Cellular density of the tissue was investigated by counting cell nuclei. The density of sympathetic nerve fibers in the fat tissue was similar in knee OA as compared to AKP. In the fat tissue, density of sensory substance P-positive nerve fibers was higher in AKP than in knee OA, which was not observed in the fibrosis capsule of the fat pad. The preponderance of sensory over sympathetic nerve fibers was accompanied by an increased cellular density in fat tissue in patients with AKP compared to knee OA. A positive correlation existed between cellularity and sensory nerve fiber density in fat tissue. This study revealed a preponderance of sensory over sympathetic innervation in the infrapatellar fat pad in AKP after primary arthroplasty of the knee, which possibly leads to aggravation and continuation of AKP and local inflammation.

Fas-induced apoptosis is a feature of progressive diabetic nephropathy in transgenic (mRen-2)27 rats: Attenuation with renin-angiotensin blockade

BACKGROUND AND AIM

Tubular atrophy is a major feature of most renal diseases and is closely associated with the loss of renal function. The present study sought to investigate whether Fas/FasL-induced tubular epithelial cell apoptosis was a feature of experimental diabetic nephropathy. The effects of renoprotective therapy with blockade of the renin-angiotensin (RAS) system were also examined.

METHOD

Six-week-old female Ren-2 rats were injected with streptozotocin and maintained diabetic for 12 weeks. Further groups of diabetic rats were treated with the angiotensin-converting enzyme inhibitor, perindopril, for 12 weeks.

RESULTS

Widespread apoptosis, identified by using mediated Terminal dUTP nick-end labelling (TUNEL) staining was noted in the tubules of diabetic Ren-2 rats. These changes were associated with an increase in both Fas mRNA and Fas L (ligand) within the tubules (P < 0.01). Treatment of diabetic Ren-2 rats with perindopril (6 mg/kg per day) reduced the apoptosis to control levels and was associated with a reduction in Fas mRNA and Fas L protein (P < 0.05).

CONCLUSION

In conclusion, Fas/Fas L-induced tubular apoptosis is a feature of diabetic Ren-2 rats and is attenuated by the blockade of the RAS.

Bench-to-bedside review: beta2-Agonists and the acute respiratory distress syndrome

The acute respiratory distress syndrome (ARDS) is a devastating constellation of clinical, radiological and pathological signs characterized by failure of gas exchange and refractory hypoxia. Despite nearly 30 years of research, no specific pharmacological therapy has yet proven to be efficacious in manipulating the pathophysiological processes that underlie this condition. Several in vitro and in vivo animal or human studies suggest a potential role for β₂-agonists in the treatment of ARDS. These agents have been shown to reduce pulmonary neutrophil sequestration and activation, accelerate alveolar fluid clearance, enhance surfactant secretion, and modulate the inflammatory and coagulation cascades. They are also used widely in clinical practice and are well tolerated in critically ill patients. The present review examines the evidence supporting a role for β₂-agonists as a specific pharmacological intervention in patients with ARDS.

Apoptosis in lung fibrosis and repair

Cell death by apoptosis has fundamental significance in both normal lung homeostasis and a variety of pathologic processes, and for this reason apoptosis in the lung is a rapidly growing area of investigation. Evidence from human lung biopsy specimens and from animal models of lung fibrosis points to important roles for apoptosis in both the pathogenesis and resolution of fibrotic lesions. As more evidence accumulates, the more apparent becomes the paucity of information on the regulation of this mode of cell death in the many different cell types of the lung parenchyma. This discussion will review the current state of knowledge regarding the roles of apoptosis in lung fibrosis and will focus on its role in pathogenesis.