Acute Respiratory Distress Syndrome In Rats Research Articles

High Expression of CXCL10/CXCR3 in Ventilator-Induced Lung Injury Caused by High Mechanical Power.

Background The energy delivered by a ventilator to the respiratory system in one minute is defined as mechanical power (MP). However, the effect of ventilator-induced lung injury (VILI) in patients suffering from acute respiratory distress syndrome (ARDS) is still unknown. Our previous studies revealed that CXCL10 may be a potential biomarker of lung injury in ARDS. Therefore, the aim of this study was to compare the lung injury of rats and patients under different MP conditions to explore the involvement of CXCL10 and its receptor CXCR3 in VILI. Methods Patients were divided into the high mechanical power group (HMPp group) and low mechanical power group (LMPp group), while rats were assigned to the high mechanical power group (HMPr group), medium mechanical power group (MMPr group), and low mechanical power group (LMPr group). CXCL10 and CXCR3 plasma content in ARDS patients and rats under ventilation at different MP was measured, as well as their protein and mRNA expression in rat lungs. Results CXCL10 and CXCR3 content in the plasma of ARDS patients in the HMPp was significantly higher than that in the LMPp. The increase of MP during mechanical ventilation in the rats gradually increased lung damage, and CXCL10 and CXCR3 levels in rat plasma gradually increased with the increase of MP. CXCL10 and CXCR3 protein and mRNA expression in the HMPr group and MMPr group was significantly higher than that in the LMPr group (P < 0.05). More mast cells were present in the trachea, bronchus, blood vessels, and lymphatic system in the rat lungs of the HMPr group, and the number of mast cells in the HMPr group (13.32 ± 3.27) was significantly higher than that in the LMPr group (3.25 ± 0.29) (P < 0.05). Conclusion The higher the MP, the more severe the lung injury, and the higher the CXCL10/CXCR3 expression. Therefore, CXCL10/CXCR3 might participate in VILI by mediating mast cell chemotaxis.

Annexin A1 peptide Ac2-26 mitigates ventilator-induced lung injury in acute respiratory distress syndrome rats and partly depended on the endothelial nitric oxide synthase pathway.

Although mechanical ventilation is an essential support for acute respiratory distress syndrome (ARDS), ventilation also leads to ventilator-induced lung injury (VILI). This study aimed to estimate the effect and mechanism of Annexin A1 peptide (Ac2-26) on VILI in ARDS rats. Thirty-two rats were randomized into the sham (S), mechanical ventilation (V), mechanical ventilation/Ac2-26 (VA), and mechanical ventilation/Ac2-26/L-NIO (VAL) groups. The S group only received anesthesia, and the other three groups received endotoxin and then ventilation for 4 h. Rats in the V, VA and VAL groups received saline, Ac2-26, and A c2-26/N5-(1-iminoethyl)-l-ornithine (L-NIO), respectively. All indexes deteriorated in the V, VA and VAL groups compared with the S group. Compared with V group, the PaO2/FiO2 ratio was increased, but the wet-to-dry weight ratio and protein levels in bronchoalveolar lavage fluid were decreased in the VA group. The inflammatory cells and proinflammatory factors were reduced by Ac2-26. The oxidative stress response, lung injury and apoptosis were also decreased by Ac2-26 compared to V group. All improvements of Ac2-26 were partly reversed by L-NIO. Ac2-26 mitigates VILI in ARDS rats and partly depended on the endothelial nitric oxide synthase pathway.

Extraction of baicalin from Scutellaria baicalensis Georgi and its alleviative effect on acute respiratory distress syndrome in rats

In this study baicalin was extracted from Scutellaria baicalensis Georgi and applied to alleviate the acute respiratory distress syndrome (ARDS) in rats. The baicalin with 89.53% purity was successfully extracted from Scutellaria baicalensis Georgi. Sixty-five rats were randomly divided into control, model and low-, middle- and high-dose baicalin groups. The oleic acid-induced ARDS model was established in model and baicalin groups. The low-, middle- and high-dose baicalin groups were treated with 100, 200 and 400 mg/kg baicalin, respectively. After 3 h from treatment, compared with model group, in baicalin groups the arterial oxygen partial pressure and oxygenation index were obviously enhanced, the left lung ratio wet weight to dry weight and number of neutrophil, total protein content, tumor necrosis factor α, interleukin 1β and interleukin 6 levels in bronchoalveolar lavage fluid were significantly decreased, and the lung tissue high-mobility group box-1 (HMGB1) and nuclear factor kappa B (NF-κB) p65 protein expression levels were significantly decreased. In conclusion, baicalin may alleviate the ARDS in rats by reducing the inflammatory response via inhibiting the HMGB1/NF-κB signal pathway.

Xuebijing Injection Ameliorates H2S-Induced Acute Respiratory Distress Syndrome by Promoting Claudin-5 Expression.

To investigate the protective effects and underlying mechanisms of Xuebijing Injection (XBJ) on the lung endothelial barrier in hydrogen sulfide (H2S)-induced acute respiratory distress syndrome (ARDS). Sprague-Dawley rats were exposed to H2S (300 ppm) to establish ARDS model, while human pulmonary microvascular endothelial cells (HPMECs) were incubated with NaHS (a H2S donor, 500 µmol/L) to establish cell model. H2S and XBJ were concurrently administered to the rat and cell models. Lung hematoxylin and eosin staining, immunohistochemistry, transmission electron microscopy and wet/dry ratio measurement were used to confirm ARDS induced by H2S in vivo. The expression levels of claudin-5, phosphorylated protein kinase B (p-AKT)/t-AKT and p-forkhead box transcription factor O1 (FoxO1)/t-FoxO1 in vivo and in vitro were also assessed. Paracellular permeability and transepithelial electrical resistance (TEER) were measured to evaluate endothelial barrier function in the cell model. The morphological investigation showed that XBJ attenuated H2S-induced ARDS in rats. XBJ significantly ameliorated both the reduction in TEER and the increased paracellular permeability observed in NaHS-treated HPMECs (P<0.05). The protective effects of XBJ were blocked by LY294002, a phosphatidylinositol 3-kinase (PI3K)/AKT/FoxO1 pathway antagonist (P<0.05). Furthermore, XBJ promoted the expression of claudin-5 and increased the levels of p-AKT and p-FoxO1 in vivo and in vitro (P<0.05). XBJ ameliorated H2S-induced ARDS by promoting claudin-5 expression via the PI3K/AKT/FoxO1 signaling pathway.

Pro-Resolving Mediator Resolvin E1 Restores Alveolar Fluid Clearance in Acute Respiratory Distress Syndrome.

Acute respiratory distress syndrome (ARDS) is a life-threatening condition characterized by increased permeability of the alveolar-capillary barrier and impaired alveolar fluid clearance. Resolvin E1 (RvE1) is a specialized pro-resolving mediator derived endogenously from omega-3-polyunsaturated fatty acids. RvE1 (10 μg/kg i.v.) was injected to rats 6 h post-lipopolysaccharide (LPS) (14 mg/kg) induction. After another 3 h, alveolar fluid clearance was measured in live rats (n = 8-9). The primary Type II alveolar epithelial cell was isolated and treated by LPS (1 μg/mL) with or without RvE1 (250 nM). The expression of epithelial sodium channel (ENaC), Na+/K+-ATPase (NKA), AKT, serum- and glucocorticoid-induced kinase 1 (SGK1), and Nedd4-2 were detected. RvE1 improved survival rate (30% vs. 70%, P = 0.048), increased the clearance of alveolar fluid (13.34% vs. 18.73%, P < 0.001), reduced lung wet-dry weight ratio (5.01 vs. 4.63, P < 0.001), mitigated lung injury scores (13.38 vs. 7.0, P < 0.05) and inflammation in LPS-induced ARDS in rats. RvE1 upregulated alveolar ENaC and NKA expression in vivo and in vitro. In addition, RvE1 significantly increased the expression of phosphorylated AKT, SGK1, and phosphorylated Nedd4-2 in LPS-stimulated primary alveolar type II cells. The effects of RvE1 were abrogated by blocking phosphatidylinositide3'-kinase (PI3K) and SGK1 with LY294002 and GSK650394, respectively. In summary, RvE1 upregulated ENaC and NKA expression by activating PI3K/AKT/SGK1 pathway to promote alveolar fluid clearance, suggesting that RvE1 may be a potentially effective drug for ARDS treatment.

Establishment of a venovenous extracorporeal membrane oxygenation in a rat model of acute respiratory distress syndrome.

Venovenous extracorporeal membrane oxygenation (VV ECMO) is now considered a reasonable option to salvage acute respiratory distress syndrome (ARDS). However, we lack a rodent model for experimental studies. This study was undertaken to establish an animal model of VV ECMO in ARDS rats. A total of 18 Sprague-Dawley (SD) rats (350 ± 50 g) were used in this study. Using a rat model of oleic acid (OA)-induced ARDS, VV ECMO was established through cavoatrial cannulation of the right jugular vein for venous drainage and venous reinfusion with a specially designed three-cavity catheter. Continuous arterial pressure monitoring was implemented by using a catheter through cannulation of the right femoral artery. The central temperature was monitored with a rectal probe. Arterial blood gas monitoring was implemented by a blood gas analyzer at three-time points: at baseline, 1-hour (after OA modeling), and 3.5-hour (after VV ECMO support). Lung tissue and bronchoalveolar lavage fluid were harvested respectively for protein concentration and pulmonary histologic evaluation to confirm the alleviation of lung injury during VV ECMO. Following ARDS induced by OA, ten rats were successfully established on VV ECMO without failure and survived the ECMO procedure. VV ECMO alleviated lung injury and restored adequate circulation for the return of lung function and oxygenation. VV ECMO was associated with decreased lung injury score, wet/dry weight ratio, and fluid leakage into airspaces. We have established a reliable, economical, and functioning ARDS rat model of VV ECMO.

Mechanosensitive Piezo1 channel activation promotes ventilator-induced lung injury via disruption of endothelial junctions in ARDS rats

ObjectiveThis study aimed to investigate the role of endothelial Piezo1 in mediating ventilator-induced lung injury secondary to acute respiratory distress syndrome (ARDS). MethodsRats and lung endothelial cells (ECs) were transfected with Piezo1 shRNA (shPiezo1) and Piezo1 siRNA, respectively, to knock down Piezo1. Intratracheal instillation or incubation with lipopolysaccharide (LPS) was used to establish an ARDS model, and high tidal volume (HVT) ventilation or 20% cyclic stretch (CS) was administered to simulate a two-hit injury. Lung injury, alterations in lung endothelial barrier, disruption of adherens junctions (AJs), and Ca2+ influx were assessed. ResultsLung vascular hyperpermeability was further increased in ARDS rats following HVT ventilation, which was abrogated in shPiezo1-treated rats. 20% CS led to severer rupture of AJs following LPS stimulation as indicated by immunofluorescence staining. The internalization and degradation of VE-cadherin were blocked by knockdown of Piezo1. Additionally, 20% CS induced Piezo1 activation, manifesting as elevated intracellular Ca2+ concentration in LPS-treated ECs, and subsequently increased calcium-dependent calpain activity. Pharmacological inhibition of calpain or Piezo1 knockdown prevented the loss of VE-cadherin, p120-catenin, and β-catenin in ARDS rats undergoing HVT ventilation and LPS-treated ECs exposed to 20% CS. ConclusionExcessive mechanical stretch during ARDS induces the activation of Piezo1 channel and its downstream target, calpain, via Ca2+ influx. This results in the disassembly of endothelial AJs and further facilitates lung endothelial barrier breakdown and vascular hyperpermeability.

Effects of different concentrations of mesenchymal stem cells treatment on LPS-induced acute respiratory distress syndrome rat model

Purpose This study was prospectively designed to investigate the effects of different concentrations of mesenchymal stem cells treatment on respiratory mechanics, oxygenation, hemodynamics and inflammatory response in LPS-induced acute respiratory distress syndrome (ARDS) rat model. Methods: One hundred and twenty six LPS-induced ARDS model rats (weighted 200-220 g) were randomly divided into three groups: 1) Control group (N = 42); 2) low-dose hUC-MSC treatment group (MSC group 1, 1x107 cell/kg, N = 42); 3) high-dose hUC-MSC treatment group (MSC group 2, 2x107 cell/kg, N = 42), sham operation group as healthy group (N = 15). The rats were observed closely for 24 hours after hUC-MSC treatment, and the survival rate was calculated. At 24 hours, all rats were tested for hemodynamics, blood gas analysis, heart, lung, liver and kidney functions, inflammatory factors detection in blood samples and broncho-alveolar lavage fluid (BALF). The lung tissue of the rats was collected for HE staining analysis. Results: After LPS injection, ARDS was obvious in all LPS-infused rat groups, consistent with severe acute lung injury and high death rate. However, compared with the control group, a single intravenous injection hUC-MSC at dose of 1 × 107 cells/kg (low dose group) and 2 × 107 cells/kg (high dose group) reduced the mortality of rats with LPS-induced ARDS, as well as improving the lung function, increased the arterial oxygen pressure, improved the heart function, and reduced the levels of inflammatory factors including IL-1β, IL-6, and TNF-α. In addition, the high dose MSC group showed better lung injury therapeutic effects than the low dose MSC group. Data from this study demonstrated that injection of hUC-MSC had a significant therapeutic effect in treating the rat model of LPS-induced ARDS and multiple organ function injury.

Silencing of long noncoding RNA H19 alleviates pulmonary injury, inflammation, and fibrosis of acute respiratory distress syndrome through regulating the microRNA-423-5p/FOXA1 axis

Purpose This study aimed to explore the regulatory effects and mechanisms of long noncoding RNA H19 (H19) on pulmonary injury, inflammation, and fibrosis of acute respiratory distress syndrome (ARDS). Materials and Methods A rat model of ARDS was established by intratracheal instillation of 2 mg/kg lipopolysaccharide (LPS). qRT-PCR was performed to detect the expression of H19, miR-423-5p, tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, monocyte chemoattractant protein (MCP)-1, and vascular endothelial growth factor (VEGF). Histology score was assessed by hematoxylin-eosin (HE) staining. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of proinflammatory cytokines and the content of VEGF in bronchoalveolar lavage fluid (BALF). The lung fibrosis was evaluated using western blot and Masson’s trichrome staining. Dual-luciferase reporter gene assay was used for confirming the relationship between miR-423-5p and H19/FOXA1 in alveolar macrophage cells (MH-S) and alveolar epithelial cells (MLE-12). The regulatory effects of H19/miR-423-5p/FOXA1 axis on the inflammation and fibrosis were further analyzed in LPS-induced MH-S cells. Results The expression of H19 and FOXA1 was significantly up-regulated, while the expression of miR-423-5p was down-regulated in LPS-induced ARDS rats. Silencing of H19 decreased the mRNA expression of TNF-α, IL-1β, IL-6, MCP-1, and VEGF, the contents of TNF-α, IL-1β, IL-6, and VEGF in BALF, and histology score in LPS-induced ARDS rats. H19 knockdown also reduced the fibrosis scores and the protein expression of vimentin and α-SMA, and elevated the protein expression of E-cadherin in LPS-induced ARDS rats. Furthermore, silencing of miR-423-5p and overexpression of FOXA1 reversed the inhibitory effects of si-H19 on the inflammation and fibrosis of LPS-induced MH-S cells. Conclusions Silencing of H19 relieved the pulmonary injury, inflammation and fibrosis of LPS-induced ARDS in rats. Silencing of H19 also alleviated the inflammation and fibrosis of LPS-induced MH-S cells through regulating the miR-423-5p/FOXA1 axis.

Effects of mechanical ventilation with different tidal volumes on right ventricular hemodynamics in acute respiratory distress syndrome rats

To explore the effect of different tidal volumes (VT) on the hemodynamics of right heart in acute respiratory distress syndrome (ARDS) rats induced by oleic acid (OA). Sixty adult male Sprague-Dawley (SD) rats were divided into control group (n = 20), ARDS model group (n = 20), low VT (LVT) group (n = 10) and high VT (HVT) group (n = 10) by random number table. ARDS model was reproduced by injecting OA 0.15 mL/kg through a jugular vein. The control group was given the same amount of normal saline. The success of modeling was judged by the oxygenation index (PaO2/FiO2) 2 hours after modeling, at the same time, the lung tissues were collected, the wet/dry weight (W/D) ratio was determined, and the lung histopathological changes were measured by lung injury score. The rats in the LVT group and HVT group were given mechanical ventilation with VT of 6 mL/kg or 20 mL/kg for 4 hours, respectively at 2 hours after modeling. The rats in the control group and the ARDS model group maintained spontaneous breathing. After mechanical ventilation for 4 hours, the heart rate (HR), right ventricular systolic pressure (RVSP), the maximum rate of rising of right ventricular pressure (dp/dt max), and the blood pressure (BP) were measured. Meanwhile, arterial blood samples were collected for blood gas analysis, including pH value, arterial partial pressure of oxygen (PaO2), arterial partial pressure of carbon dioxide (PaCO2) and PaO2/FiO2. The rats in the ARDS model group showed symptoms of respiratory distress 1 hour after modeling, and the lung tissue samples showed obvious patchy bleeding 2 hours after modeling, while the control group showed no such changes. The PaO2/FiO2 in the ARDS model group was significantly lower than that in the control group [mmHg (1 mmHg = 0.133 kPa): 294.3±5.9 vs. 459.0±4.4, P < 0.01], and the lung W/D ratio and lung injury score were significantly higher (lung W/D ratio: 8.24±0.25 vs. 4.48±0.13, lung injury score: 0.60±0.03 vs. 0.12±0.02, both P < 0.01). It indicated that ARDS model was successfully reproduced. The arterial blood gas analysis and hemodynamic parameters of the ARDS model group were significantly worse than those of the control group. After 4-hour mechanical ventilation, the blood gas parameters of the LVT group were better than those of the ARDS model group and the HVT group [pH value: 7.36±0.02 vs. 7.24±0.02, 7.13±0.01; PaO2 (mmHg): 92.4±2.1 vs. 61.8±2.3, 76.6±2.2; PaCO2 (mmHg): 49.6±1.7 vs. 61.8±1.8, 33.6±1.3; PaO2/FiO2 (mmHg): 440.0±10.2 vs. 274.3±21.4, 364.7±10.5; all P < 0.05]. HR, BP and dp/dt max in the LVT group were significantly higher than those in the ARDS model group and the HVT group [HR (bpm): 346.9±5.4 vs. 302.3±10.1, 265.5±12.2; BP (mmHg): 125.4±2.2 vs. 110.0±2.5, 89.2±2.8; dp/dt max (mmHg/s): 1 393.3±30.3 vs. 1 236.4±20.5, 896.1±19.5; all P < 0.05], and RVSP was significantly lower than that in the ARDS model group and the HVT group (mmHg: 31.3±0.4 vs. 34.0±1.0, 38.8±0.9, both P < 0.05). Mechanical ventilation with low VT can improve the hemodynamic parameters of the right ventricle and protect the function of the right heart in ARDS rats.

Ac2-26 mitigated acute respiratory distress syndrome rats via formyl peptide receptor pathway

Background Acute respiratory distress syndrome (ARDS) is characterized by severe local and systemic inflammation. Ac2-26, an Annexin A1 Peptide, can reduce the lung injury induced by reperfusion via the inhibition of inflammation. The present study aims to evaluate the effect and mechanism of Ac2-26 in ARDS. Methods Thirty-two rats were anaesthetized and randomized into four groups: sham (S), ARDS (A), ARDS/Ac2-26 (AA), and ARDS/Ac2-26/BOC-2 (AAB) groups. Rats in the S group received saline for intratracheal instillation, while rats in the other three groups received endotoxin for intratracheal instillation, in order to prepare the ARDS and inject the saline, Ac2-26, and Ac2-26 combined with BOC-2. After 24 h, the PaO2/FiO2 ratio was calculated. The lung tissue wet-to-dry weight ratio and the protein level in bronchoalveolar lavage fluid (BALF) were tested. Then, the cytokines in BALF and serum, and the inflammatory cells in BALF were investigated. Afterwards, the oxidative stress response and histological injury was evaluated. Subsequently, the epithelium was cultured and analyzed to estimate the effect of Ac2-26 on apoptosis. Results Compared to the S group, all indexes worsened in the A, AA, and AAB groups. Furthermore, compared to the S group, Ac2-26 significantly improved the lung injury and alveolar-capillary permeability, and inhibited the oxidative stress response. In addition, Ac2-26 reduced the local and systemic inflammation through the regulation of pro- and anti-inflammatory cytokines, and the decrease in inflammatory cells in BALF. Moreover, Ac2-26 inhibited the epithelium apoptosis induced by LPS through the modulation of apoptosis-regulated proteins. The protective effect of Ac2-26 on ARDS was partially reversed by the FPR inhibitor, BOC-2. Conclusion Ac2-26 reduced the lung injury induced by LPS, promoted alveolar-capillary permeability, ameliorated the local and systemic inflammation, and inhibited the oxidative stress response and apoptosis. The protection of Ac2-26 on ARDS was mainly dependent on the FPR pathway.

Colchicine reduces lung injury in experimental acute respiratory distress syndrome.

The acute respiratory distress syndrome (ARDS) is characterized by intense dysregulated inflammation leading to acute lung injury (ALI) and respiratory failure. There are no effective pharmacologic therapies for ARDS. Colchicine is a low-cost, widely available drug, effective in the treatment of inflammatory conditions. We studied the effects of colchicine pre-treatment on oleic acid-induced ARDS in rats. Rats were treated with colchicine (1 mg/kg) or placebo for three days prior to intravenous oleic acid-induced ALI (150 mg/kg). Four hours later they were studied and compared to a sham group. Colchicine reduced the area of histological lung injury by 61%, reduced lung edema, and markedly improved oxygenation by increasing PaO2/FiO2 from 66 ± 13 mmHg (mean ± SEM) to 246 ± 45 mmHg compared to 380 ± 18 mmHg in sham animals. Colchicine also reduced PaCO2 and respiratory acidosis. Lung neutrophil recruitment, assessed by myeloperoxidase immunostaining, was greatly increased after injury from 1.16 ± 0.19% to 8.86 ± 0.66% and significantly reduced by colchicine to 5.95 ± 1.13%. Increased lung NETosis was also reduced by therapy. Circulating leukocytosis after ALI was not reduced by colchicine therapy, but neutrophils reactivity and CD4 and CD8 cell surface expression on lymphocyte populations were restored. Colchicine reduces ALI and respiratory failure in experimental ARDS in relation with reduced lung neutrophil recruitment and reduced circulating leukocyte activation. This study supports the clinical development of colchicine for the prevention of ARDS in conditions causing ALI.

Effect of SIS3 on Extracellular Matrix Remodeling and Repair in a Lipopolysaccharide-Induced ARDS Rat Model.

The remodeling of the extracellular matrix (ECM) in the parenchyma plays an important role in the development of acute respiratory distress syndrome (ARDS), a disease characterized by lung injury. Although it is clear that TGF-β1 can modulate the expression of the extracellular matrix (ECM) through intracellular signaling molecules such as Smad3, its role as a therapeutic target against ARDS remains unknown. In this study, a rat model was established to mimic ARDS via intratracheal instillation of lipopolysaccharide (LPS). A selective inhibitor of Smad3 (SIS3) was intraperitoneally injected into the disease model, while phosphate-buffered saline (PBS) was used in the control group. Animal tissues were then evaluated using histological analysis, immunohistochemistry, RT-qPCR, ELISA, and western blotting. LPS was found to stimulate the expression of RAGE, TGF-β1, MMP2, and MMP9 in the rat model. Moreover, treatment with SIS3 was observed to reverse the expression of these molecules. In addition, pretreatment with SIS3 was shown to partially inhibit the phosphorylation of Smad3 and alleviate symptoms including lung injury and pulmonary edema. These findings indicate that SIS3, or the blocking of TGF-β/Smad3 pathways, could influence remodeling of the ECM and this may serve as a therapeutic strategy against ARDS.

The protective effects of C16 peptide and angiopoietin-1 compound in lipopolysaccharide-induced acute respiratory distress syndrome.

C16 peptide and angiopoietin-1 (Ang-1) have been found to have anti-inflammatory activity in various inflammation-related diseases. However, their combined role in acute respiratory distress syndrome (ARDS) has not been investigated yet. The objective of this study was to investigate the effects of C16 peptide and Ang-1 in combination with lipopolysaccharide (LPS)-induced inflammatory insult in vitro and in vivo. Human pulmonary microvascular endothelial cells and human pulmonary alveolar epithelial cells were used as cell culture systems, and an ARDS rodent model was used for in vivo studies. Our results demonstrated that C16 and Ang-1 in combination significantly suppressed inflammatory cell transmigration by 33% in comparison with the vehicle alone, and decreased the lung tissue wet-to-dry lung weight ratio to a maximum of 1.53, compared to 3.55 in the vehicle group in ARDS rats. Moreover, C + A treatment reduced the histology injury score to 60% of the vehicle control, enhanced arterial oxygen saturation (SO2), decreased arterial carbon dioxide partial pressure (PCO2), and increased oxygen partial pressure (PO2) in ARDS rats, while also improving the survival rate from 47% (7/15) to 80% (12/15) and diminishing fibrosis, necrosis, and apoptosis in lung tissue. Furthermore, when C + A therapy was administered 4 h following LPS injection, the treatment showed significant alleviating effects on pulmonary inflammatory cell infiltration 24 h postinsult. In conclusion, our in vitro and in vivo studies show that C16 and Ang-1 exert protective effects against LPS-induced inflammatory insult. C16 and Ang-1 hold promise as a novel agent against LPS-induced ARDS. Further studies are needed to determine the potential for C16 and Ang-1 in combination in treating inflammatory lung diseases.

Moderate Fever Cycles as a Potential Mechanism to Protect the Respiratory System in COVID-19 Patients.

Mortality in COVID-19 patients predominantly results from an acute respiratory distress syndrome (ARDS), in which lungs alveolar cells undergo programmed cell death. Mortality in a sepsis-induced ARDS rat model is reduced by adenovirus over-expression of the HSP70 chaperone. A natural rise of body temperature during mild fever can naturally accumulate high cellular levels of HSP70 that can arrest apoptosis and protect alveolar lung cells from inflammatory damages. However, beyond 1–2 h of fever, no HSP70 is being further produced and a decreased in body temperature required to the restore cell's ability to produce more HSP70 in a subsequent fever cycle. We suggest that antipyretics may be beneficial in COVID-19 patients subsequent to several hours of mild (<38.8°C) advantageous fever, allowing lung cells to accumulate protective HSP70 against damages from the inflammatory response to the virus SARS-CoV-2. With age, the ability to develop fever and accumulate HSP70 decreases. This could be ameliorated, when advisable to do so, by thermotherapies and/or physical training.

Alleviation of Lipopolysaccharide-Induced Acute Respiratory Distress Syndrome in Rats by Yiqi Huayu Jiedu Decoction: A Tandem Mass Tag-Based Proteomics Study.

BackgroundTo study the effect of Yiqi Huayu Jiedu Decoction (YQHYJD) on protein expression in the lung tissue of acute respiratory distress syndrome (ARDS) rats and to explore the underlying molecular therapeutic mechanism of YQHYJD.MethodsSprague Dawley rats were administered with YQHYJD by oral gavage for 1 week. The rats were injected with lipopolysaccharide (LPS) to induce ARDS. The lung injury was assessed pathologically. Differentially expressed proteins (DEPs) were screened by quantitative proteomics and analyzed using bioinformatic tools, such as Metascape and Kyoto Encyclopedia of Genes and Genomes (KEGG) mapper. DEPs were verified by parallel reaction monitoring (PRM).ResultsYQHYJD alleviated the LPS-induced pathological damage of lung tissue in rats. There were 134 DEPs among the YQHYJD treatment and model groups. The Genomes pathway analyses revealed that the DEPs were closely related to immune system pathway. The mass spectrometry analysis revealed that YQHYJD exhibits a protective effect on lung tissue by significantly upregulating hematopoietic cell kinase (Hck), phospholipid phosphatase 3 (Plpp3), myristoylated-alanine rich C-kinase substrate (Marcks), and Actin-related protein 2/3 complex subunit 2 (Arpc2), which are related to Fc gamma receptor-mediated phagocytosis pathway.ConclusionYQHYJD can alleviate the lung injury of ARDS rats by regulating the Fc gamma receptor-mediated phagocytosis pathway, which is related to immune system.

Natural and engineered chemokine (C-X-C motif) receptor 4 agonists prevent acute respiratory distress syndrome after lung ischemia\u2013reperfusion injury and hemorrhage

We compared therapeutic properties of natural and engineered chemokine (C-X-C motif) receptor 4 (CXCR4) agonists in a rat acute respiratory distress syndrome (ARDS) model utilizing the PaO2/FiO2-ratio as a clinically relevant primary outcome criterion. Ventilated rats underwent unilateral lung ischemia from t = 0–70 min plus hemorrhage to a mean arterial blood pressure (MAP) of 30 mmHg from t = 40–70 min, followed by reperfusion/fluid resuscitation until t = 300 min. Natural CXCR4 agonists (CXCL12, ubiquitin) and engineered CXCL12 variants (CXCL121, CXCL22, CXCL12K27A/R41A/R47A, CXCL12 (3–68)) were administered within 5 min of fluid resuscitation. Animals treated with vehicle or CXCL12 (3–68) reached criteria for mild and moderate ARDS between t = 90–120 min and t = 120–180 min, respectively, and remained in moderate ARDS until t = 300 min. Ubiquitin, CXCL12, CXCL121 and CXCL122 prevented ARDS development. Potencies of CXCL12/CXCL121/CXCL122 were higher than the potency of ubiquitin. CXCL12K27A/R41A/R47A was inefficacious. CXCL121 > CXCL12 stabilized MAP and reduced fluid requirements. CXCR4 agonists at doses that preserved lung function reduced histological injury of the post-ischemic lung and reduced mortality from 55 to 9%. Our findings suggest that CXCR4 protein agonists prevent development of ARDS and reduce mortality in a rat model, and that development of new engineered protein therapeutics with improved pharmacological properties for ARDS is possible.

Coronavirus Disease 2019 and Hypertension: The Role of Angiotensin-Converting Enzyme 2 and the Renin-Angiotensin System.

Hypertension emerged from early reports as a potential risk factor for worse outcomes for persons with coronavirus disease 2019 (COVID-19). Among the putative links between hypertension and COVID-19 is a key counter-regulatory component of the renin-angiotensin system (RAS): angiotensin-converting enzyme 2 (ACE2). ACE2 facilitates entry of severe acute respiratory syndrome coronavirus 2, the virus responsible for COVID-19, into host cells. Because RAS inhibitors have been suggested to increase ACE2 expression, health-care providers and patients have grappled with the decision of whether to discontinue these medications during the COVID-19 pandemic. However, experimental models of analogous viral pneumonias suggest RAS inhibitors may exert protective effects against acute lung injury. We review how RAS and ACE2 biology may affect outcomes in COVID-19 through pulmonary and other systemic effects. In addition, we briefly detail the data for and against continuation of RAS inhibitors in persons with COVID-19 and summarize the current consensus recommendations from select specialty organizations.

α2A -AR antagonism by BRL-44408 maleate attenuates acute lung injury in rats with downregulation of ERK1/2, p38MAPK, and p65 pathway.

Acute respiratory distress syndrome (ARDS), characterized by acute hypoxic respiratory dysfunction or failure, is a manifestation of multiple organ failure in the lung, and the most common risk factor is sepsis. We previously showed that blocking α2 -adrenoceptor (α2 -AR) could attenuate lung injury induced by endotoxin in rats. α2A -adrenoceptor (α2A -AR), a subtype of α2 -AR plays a key role in inflammatory diseases, but the mechanism remains unknown. Here, we explored the effect of BRL-44408 maleate (BRL), a specific α2A -AR antagonist, on cecal ligation puncture (CLP)-induced ARDS in rats and the underlying mechanism. Preadministration of BRL-44408 maleate significantly alleviated CLP-induced histological injury, macrophage infiltration, inflammatory response, and wet/dry ratio in lung tissue. However, there was no statistical difference in survival rate between the CLP and CLP+BRL groups. Extracellular regulated protein kinase (ERK1/2), p38MAPK, and p65 were activated in the CLP group, and BRL-44408 maleate inhibited the activation of these signal molecules, c-Jun N-terminal kinase (JNK) and protein kinase A (PKA) showed no changes in activation between these two groups. BRL-44408 maleate decreased lipopolysaccharide (LPS)-induced expression of cytokines in NR8383 rat alveolar macrophages and reduced phosphorylation of ERK1/2, p38MAPK, and p65. JNK and PKA were not influenced by LPS. Together, these findings suggest that antagonism of α2A -AR improves CLP-induced acute lung injury and involves the downregulation of ERK1/2, p38MAPK, and p65 pathway independent of the activation of JNK and PKA.

Electroacupuncture Pretreatment Alleviates LPS-Induced Acute Respiratory Distress Syndrome via Regulating the PPAR Gamma/NF-Kappa B Signaling Pathway.

Electroacupuncture (EA) is reported to possess anti-inflammatory properties and has beneficial effects on acute respiratory distress syndrome (ARDS). However, the underlying mechanisms of the effects of EA on ARDS remain unclear. This study aims to investigate the protective effect of EA on LPS-induced ARDS. In this study, Sprague-Dawley male rats were treated with EA at Hegu (LI4) for 45 minutes before LPS instillation (0.4 mg/kg, 100 ul). H&E staining, wet-to-dry weight (W/D) ratio, PaO2, and protein content in BALF were employed to determine the function of lung tissues. Inflammatory cytokines in serum and BALF were detected by enzyme-linked immunoassay assay (ELISA). The levels of oxidative stress markers were detected to determine the oxidative stress status. Cell apoptosis was observed by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and western blot. Here, we found that EA pretreatment effectively alleviated lung pathological damage. Moreover, EA suppressed the oxidative stress damage by upregulating glutathione and superoxide dismutase and downregulating malondialdehyde. EA pretreatment also regulated apoptosis-related proteins, such as Bax and Bcl-2. We found that peroxisome proliferators-activated receptors γ (PPARγ) play a critical role during ARDS, EA up-regulated the expression of PPARγ, which inhibited the activation of nuclear factor-kappa B (NF-κB) and decreased the inflammatory cytokines (interleukin-1β, interleukin-6, and tumor necrosis factor-α). When rats were treated with GW9662, a selective PPARγ antagonist, these effects of EA were reversed. Our study demonstrated that EA pretreatment had a beneficial effect on LPS-induced ARDS in rats by anti-inflammatory, antioxidative, and antiapoptotic properties which was regulated via PPARγ/NF-κB signaling pathway.