Theoretical and Experimental Studies on Plant Light-Dependent Protochlorophyllide Oxidoreductase as a Novel Target for Searching Potential Herbicides.

Herbicide resistance is a prevalent problem that has posed a foremost challenge to crop production worldwide. Light-dependent enzyme NADPH: protochlorophyllide oxidoreductase (LPOR) in plants is a metabolic target that could satisfy this unmet demand. Herein, for the first time, we embarked on proposing a new mode of action of herbicides by performing structure-based virtual screening targeting multiple LPOR binding sites, with the determination of further bioactivity on the lead series. The feasibility of exploiting high selectivity and safety herbicides targeting LPOR was discussed from the perspective of the origin and phylogeny. Besides, we revealed the structural rearrangement and the selection key for NADPH cofactor binding to LPOR. Based on these, multitarget virtual screening was performed and the result identified compounds 2 affording micromolar inhibition, in which the IC50 reached 4.74 µM. Transcriptome analysis revealed that compound 2 induced more genes related to chlorophyll synthesis in Arabidopsis thaliana, especially the LPOR genes. Additionally, we clarified that these compounds binding to the site enhanced the overall stability and local rigidity of the complex systems from molecular dynamics simulation. This study delivers a guideline on how to assess activity-determining features of inhibitors to LPOR and how to translate this knowledge into the design of novel and effective inhibitors against malignant weed that act by targeting LPOR.

Using a Dynamic Hydrophilization Strategy to Achieve Nanodispersion, Full Wetting, and Precise Delivery of Hydrophobic Pesticide.

Various strategies have been developed to improve the applicability of hydrophobic pesticides for better effectiveness in agriculture. However, existing formulations of hydrophobic pesticides still suffer from complicated processing, abused organic solvents, indispensable surfactants, or inescapable ecotoxicity, which strictly limit their applications. Herein, a dynamic covalent bond tailored pesticide (fipronil) amphiphile is constructed to address the above issues, which accomplishes the nanodispersion, full wetting, and precise delivery without organic solvents, surfactants, and materials simultaneously. By introducing a hydrophilic ligand on the hydrophobic fipronil through an imine bond, the cleavable fipronil amphiphile (FPP) exhibits superior water solubility and can even self-assemble into micelles at higher concentrations, which can be directly applied in powder form without organic solvents. Attributed to the suitable hydrophilic/hydrophobic ratio, FPP achieves full wetting and effective deposition on superhydrophobic rice leaves without surfactants. Moreover, benefiting from the unique dynamic nature of the imine bond, FPP maintains good storage stability while sensitively releasing back to fipronil under the humidity and pH trigger, consequently implementing the precise delivery for nontarget Apis cerana and target Chilo suppressalis without materials. To our knowledge, this dynamic covalent bond tailored amphiphile strategy is the first idea that simultaneously takes the dispersibility, wettability, and responsiveness of hydrophobic pesticides into account, providing a possibility to control the entire journey of field application and even promising to be incorporated into the synthesis process, thus paving the way for modern sustainable agriculture.

Investigation on the interaction of pyrethroid pesticides to estrogen receptor alpha through computational and experimental methods.

Pyrethroid insecticides are a group of widely used bio-mimetic synthetic pesticides. However, recent studies reported that they could have an accumulation effect in human which may cause series of health problems. Estrogen receptors (ER) are a class of nuclear receptors that are vital in proper physiological behavior of estrogens. To investigate the reproductive toxicity of pyrethroids, homology modeling, molecular docking, molecular dynamic simulations (MDs) were conducted to explore the interaction between pyrethroids and ERα from atomic scale. The human ERα (2YJA) was selected as a template protein for homology modeling. Then eight typical pyrethroids and positive control estradiol were docked to the modeled protein. The highest scoring bifenthrin and the lowest scoring permethrin were chosen for in-depth analysis. MDs showed that the complex formed by permethrin with ERα had a lower RMSD value and binding free energies compared to bifenthrin. Based on these results from microscopic dimension, exposure experiments were implemented to validate the primary conclusions. VTG concentrations in male zebrafish's blood were significantly higher under permethrin exposure than bifenthrin, suggesting a stronger estrogenic activity and binding propensity. In this regard, the structural characteristics of molecules were analyzed, expecting to provide theoretical references for subsequent drug design and rational drug application.

Role of Thylakoid Lipids in Protochlorophyllide Oxidoreductase Activation: Allosteric Mechanism Elucidated by a Computational Study.

Light-dependent protochlorophyllide oxidoreductase (LPOR) is a chlorophyll synthetase that catalyzes the reduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide) with indispensable roles in regulating photosynthesis processes. A recent study confirmed that thylakoid lipids (TL) were able to allosterically enhance modulator-induced LPOR activation. However, the allosteric modulation mechanism of LPOR by these compounds remains unclear. Herein, we integrated multiple computational approaches to explore the potential cavities in the Arabidopsis thaliana LPOR and an allosteric site around the helix-G region where high affinity for phosphatidyl glycerol (PG) was identified. Adopting accelerated molecular dynamics simulation for different LPOR states, we rigorously analyzed binary LPOR/PG and ternary LPOR/NADPH/PG complexes in terms of their dynamics, energetics, and attainable allosteric regulation. Our findings clarify the experimental observation of increased NADPH binding affinity for LPOR with PGs. Moreover, the simulations indicated that allosteric regulators targeting LPOR favor a mechanism involving lid opening upon binding to an allosteric hinge pocket mechanism. This understanding paves the way for designing novel LPOR activators and expanding the applications of LPOR.

Structure and Function of the Refined C-Terminal Loop in Imidazole Glycerol Phosphate Dehydratase from Different Homologs.

IGPD is an essential metalloenzyme that catalyzes histidine biosynthesis. We found that its C-terminus loop region has a vital role in determining enzyme activity but has been hardly mentioned before. In this work, we focused on the dynamic feature and function of C-Loop in Arabidopsis thaliana and Saccharomyces cerevisiae IGPD (At_IGPD and Sc_IGPD, respectively). Due to the high flexibility of this region, we performed a total of 3.4 µs of accelerated molecular dynamics simulation to enhance sampling. Inhibitor C348 in At-IGPD exhibited instability in the later stage of simulation, while the characteristic sequence in Sc_IGPD reduced solvent interference and significantly restrained the interaction mode. For the C-Loop-assisted ligand-binding process, we proposed a "Lock-Lid" model. Meanwhile, the dissociated ligand in At_IGPD served as a probe, a metastable pocket was determined at the root of C-Loop, and its rationality was proved by theoretical verification and enzyme mutation experiments. This study complemented the important structural features of C-Loop and provided a basis for the design of selective inhibitors. Considering the absence in mammals, we suggested that IGPD could be a promising germicide target.

Study on the binding mechanism of thiamethoxam with three model proteins:spectroscopic studies and theoretical simulations.

As a top-selling neonicotinoid insecticide widely used in the field, thiamethoxam is an environmental pollutant because of the accumulation in ecosystem and has also been reported that it has potential risks to the health of mammals even humans. In order to understand the binding mechanism of thiamethoxam with biological receptors, spectroscopic techniques and theoretical simulations was used to explore the specific interactions between thiamethoxam and proteins. Interestingly, the results indicated that hydrophobic interaction as the main driving force, thiamethoxam formed a single binding site complex with proteins spontaneously, resulting in a decrease in the esterase-like activity of human serum albumin. The results of computer simulation showed that there were hydrophobic, electrostatic and hydrogen bonding interactions between thiamethoxam and receptors. The results of experiment and computer simulation were mutually confirmed, so a model was established for the interaction between the two which uncovered the structural characteristics of the binding site. This research provided new insights for the structure optimization of thiamethoxam, as well as gave an effective reference for evaluating the risk of thiamethoxam systemically in the future.

Identification of novel insect ß-N-acetylhexosaminidase OfHex1 inhibitors based on virtual screening, biological evaluation, and molecular dynamics simulation.

Chitin can be widely found in the fungal cell wall, nematode eggshells, and the exoskeleton of arthropods; however, it is completely absent from higher plants and mammals. The process of chitin degradation is essential for both growth and maturation of insects. Thus, inhibiting chitin degradation is a promising strategy for the control and management of pests. The chitinolytic ß-N-acetyl-D-hexosaminidase OfHex1 of Ostrinia furnacalis (one of the most destructive pests) has been suggested as a potential target for the design of eco-friendly pesticides. This study presents the sequential virtual screening of the ZINC library with 8 million compounds, targeting OfHex1. After confirmation via enzyme inhibition experiments, compound 5 exhibited potential inhibitory activity against OfHex1 with a Ki of 28.9 ± 0.5 µM and significant selectivity (IC50 > 100 µM against HsHexB and hOGA). Molecular dynamics simulations combined with binding free energy and free energy decomposition calculations were conducted to investigate the molecular basis underlying the potency of these inhibitors toward OfHex1. The present work provides useful information for the future rational design of novel and potent OfHex1 inhibitorsCommunicated by Ramaswamy H. Sarma.

Computational and experimental investigations on the interactions of aryloxy-phenoxy-propionate herbicides to estrogen receptor alpha in zebrafish.

When the amount of pesticide exceeds the self-purification ability of the environment, it will be enriched in the human body through the atmosphere, soil, water circulation, etc., threatening human health. Aryloxy-phenoxy-propionate (APP) herbicides are a class of acetyl-CoA carboxylase (ACCase) inhibitor herbicides, widely used in field-weeding of soybean, cabbage, peanut and other crops. However, due to the water circulation, surface runoff and the agronomic practices such as watering irrigation, APP herbicides have the risk of polluting water and destroying the living environment of aquatic organisms. In this paper, a multistep framework combining homology modeling, molecular docking and molecular dynamic simulations were adopted to explore the interactions between APP herbicides and zebrafish estrogen receptor α (ERα) to investigate the estrogenic activities of the herbicides. The structure of zebrafish ERα was modeled by homology modeling, using the human's estrogen receptor α (PDB ID:2YJA) as the template. Then, eight typical APP herbicides were selected to dock with the zebrafish ERα, and it was determined that there were clear interactions between the herbicides and the receptor. The binding patterns of Quizalofop-P-ethyl (QPE), Clodinafop-propargyl (CP) and Haloxyfop-P (HP) with ERα were further investigated by molecular dynamics and binding free energy calculation. The results showed the van der Waals force and electrostatic force were the main driving forces for maintaining the stability of the complex system. In order to verify the theoretical prediction, an exposed experiment was conducted to study the effects of different concentrations of herbicides on VTG level of zebrafish in vivo and the results were consistent with the computational method. The results of this study revealed the mechanism of the action between APP herbicides and zebrafish estrogen receptors, and also provided ideas for optimizing the herbicides.

Development of sodium glucose co-transporter 2 (SGLT2) inhibitors with novel structure by molecular docking and dynamics simulation.

In this study, molecular docking studies were carried out to explore the binding interactions of sodium glucose co-transporter 2 (SGLT2) with its inhibitors. A correlation between the docking scores and the experimental bioactivity was observed (R2 = 0.8368, N = 24). The new inhibitors were designed using the 3D quantitative structure activity relationship (3D-QSAR) method, and the activities were predicted by the docking method. In order to understand the structure-activity correlation of compound 1 m (the highest score of docking) and compound 1 t (the lowest score), we carried out a combined molecular dynamics simulation and MM-GBSA method. It was found that, in the system of SGLT2-1 m, the interaction between Gln271 and Val272 exhibited significant effects, which were absent in the SGLT2-1 t system. This study is expected to shed light on the mechanism of action of compound 1 m, leading to development of active drug candidates targeting SGLT2.

Computational Studies on the Potency and Selectivity of PUGNAc Derivatives Against GH3, GH20, and GH84 ß-N-acetyl-D-hexosaminidases.

ß-N-acetyl-D-hexosaminidases have attracted significant attention due to their crucial role in diverse physiological functions including antibacterial synergists, pathogen defense, virus infection, lysosomal storage, and protein glycosylation. In particular, the GH3 ß-N-acetyl-D-hexosaminidase of V. cholerae (VcNagZ), human GH20 ß-N-acetyl-D-hexosaminidase B (HsHexB), and human GH84 ß-N-acetyl-D-hexosaminidase (hOGA) are three important representative glycosidases. These have been found to be implicated in ß-lactam resistance (VcNagZ), lysosomal storage disorders (HsHexB) and Alzheimer's disease (hOGA). Considering the profound effects of these three enzymes, many small molecule inhibitors with good potency and selectivity have been reported to regulate the corresponding physiological functions. In this paper, the best-known inhibitors PUGNAc and two of its derivatives (N-valeryl-PUGNAc and EtBuPUG) were selected as model compounds and docked into the active pockets of VcNagZ, HsHexB, and hOGA, respectively. Subsequently, molecular dynamics simulations of the nine systems were performed to systematically compare their binding modes from active pocket architecture and individual interactions. Furthermore, the binding free energy and free energy decomposition are calculated using the MM/GBSA methods to predict the binding affinities of enzyme-inhibitor systems and to quantitatively analyze the contribution of each residue. The results show that PUGNAc is deeply-buried in the active pockets of all three enzymes, which indicates its potency (but not selectivity) against VcNagZ, HsHexB, and hOGA. However, EtBuPUG, bearing branched 2-isobutamido, adopted strained conformations and was only located in the active pocket of VcNagZ. It has completely moved out of the pocket of HsHexB and lacks interactions with HsHexB. This indicates why the selectivity of EtBuPUG to VcNagZ/HsHexB is the largest, reaching 968-fold. In addition, the contributions of the catalytic residue Asp253 (VcNagZ), Asp254 (VcNagZ), Asp175 (hOGA), and Asp354 (HsHexB) are important to distinguish the activity and selectivity of these inhibitors. The results of this study provide a helpful structural guideline to promote the development of novel and selective inhibitors against specific ß-N-acetyl-D-hexosaminidases.

Unravelling the binding affinity between model transport protein and a prospective tuberculosis therapeutic agent: a spectroscopic and theoretical simulation exploration.

Haloxyfop was reported to exhibit inhibition effect targeting Mycobacterium tuberculosis and pathogenic parasites. To pave its way for drug development, more research is required to determine the affinities interacting with biological receptors in vivo. In this work, the interactions of Haloxyfop with two model transport proteins were investigated by spectroscopic techniques and theoretical simulation. The interaction mechanism, thermodynamic properties and the impact of Haloxyfop-induced conformational change in serum albumins were revealed by series of fluorescence, UV-Vis absorption and circular dichroic spectroscopy. The specific binding sites were determined by site-competitive replacement experiment. Molecular docking and dynamic simulation provided a visual screening in the microscopic binding mode. The structure of Haloxyfop was roughly divided into three parts that exhibit different covalent interaction affinities. The two isomers of Haloxyfop showed a certain degree of affinity difference. Hydrophobic, polar interaction and π-effect were analyzed in detail, and the surface electrostatic potential energy maps were simulated to provide references. The free energy, calculated by the molecular mechanics-generalized born surface area (MM-GBSA) and molecular mechanics-Poisson Boltzmann surface area (MM-PBSA) methods, was decomposed to per-residues, which intuitively revealed relevant contributions in binding process. The role of water existence was explored through molecular dynamic refinement, and the frontier molecular orbital analysis explored the ionic interaction mechanism in electronic level. In general, multiple chemistry method was adopted to fully unravel the properties of Haloxyfop-binding for the sake of rationalizing the applicability as a therapeutic agent. Communicated by Ramaswamy H. Sarma.

Effects of maternal retinoic acid administration on lung angiogenesis in oligohydramnios-exposed fetal rats.

BACKGROUND: All-trans retinoic acid (ATRA) induces in vitro angiogenesis and vascular endothelial growth factor (VEGF) secretion. Prenatal administration of vitamin A tends to increase the pulmonary and plasma levels of VEGF in the developing mouse. The aims of this study were to examine the effects of maternal retinoic acid treatment on lung VEGF expression and angiogenesis in oligohydramnios-exposed fetal rats. METHODS: On day 16 of gestation, pregnant Sprague-Dawley rats were randomly assigned to either the retinoic acid group (intragastric ATRA at 10 mg/kg body weight) or the vehicle group. We punctured each uterine sac to produce oligohydramnios, and fetuses in the opposite uterine horn served as controls. On day 21 of gestation, the fetuses were delivered by cesarean section. RESULTS: Rats exposed to oligohydramnios exhibited lower lung weights and lung/body weight ratios, and ATRA exhibited no effects on the body or lung weights of oligohydramnios-exposed rats. Lung microvessel density decreased in oligohydramnios-exposed rats of maternal vehicle-treated dams. Microvessel density was comparable between the oligohydramnios + retinoic acid group and the control + retinoic acid group. VEGF expression was comparable among control and oligohydramnios-exposed rats of maternal vehicle- or retinoic acid-treated dams. CONCLUSION: Maternal retinoic acid treatment did not increase lung VEGF expression or enhance lung development in oligohydramnios-exposed fetal rats. These results do not support the use of maternal retinoic acid to prevent oligohydramnios-induced pulmonary hypoplasia in the pseudoglandular stage.

Versatile RBC-derived vesicles as nanoparticle vector of photosensitizers for photodynamic therapy.

Various nanocarriers for photosensitizers have been developed to solve the problems of limiting the clinical utility of photodynamic therapy (PDT); however, to date, no carriers capable of supplying oxygen have been reported. We reported the development of a novel system composed of red blood cell (RBC)-derived vesicles (RDVs) generated by osmotic stress and demonstrated the capacity of RDVs for encapsulating and delivering external cargo into targeted cells due to the cellular uptake of RDVs. In this study, protoporphyrin IX (PpIX)-encapsulated RDVs (PpIX@RDVs) were prepared by the hypotonic incorporation of PpIX into RDVs in an aqueous environment, characterized, and utilized for PDT of cancer. PpIX@RDVs were rapidly uptaken by tumor cells via endocytosis in vitro, and the highly phototoxic effect of PpIX@RDVs was demonstrated upon irradiation. Superoxide anion (O(2)˙) and singlet oxygen ((1)O(2)) were involved in PpIX@RDV-induced cell apoptosis and necrosis. Finally, we demonstrated that RDVs with an oxygen supply capacity have potential as versatile delivery vehicles for efficient PDT.

A two-dimensional coordination polymer containing a two-dimensional zinc-carboxylate layer constructed from helical chains: poly[(µ4-benzene-1,2-dicarboxylato)zinc(II)].

The title compound, [Zn(C(8)H(4)O(4))](n), consists of one Zn(II) cation and one benzene-1,2-dicarboxylate dianion (BDC(2-)) as the building unit. The Zn(II) cation is four-coordinated by four carboxylate O atoms from four dianionic BDC(2-) ligands in a distorted tetrahedral geometry. The Zn(II) cations are linked by the BDC(2-) ligands to generate a structure featuring two-dimensional zinc-carboxylate layers containing left- and right-handed helical chains. The two-dimensional layers are stacked along the a direction. The thermal stability of the title compound has been studied.

Tissue plasminogen activator attenuates ventilator-induced lung injury in rats.

AIM: To test the hypothesis that the tissue plasminogen activator (tPA) may counteract the inhibitory effect of plasminogen activator inhibitors (PAI) and attenuate lung injury in a rat model of ventilator-induced lung injury (VILI). METHODS: Adult male Sprague-Dawley rats were ventilated with a HVZP (high-volume zero PEEP) protocol for 2 h at a tidal volume of 30 mL/kg, a respiratory rate of 25 breaths/min, and an inspired oxygen fraction of 21%. The rats were divided into 3 groups (n=7 for each): HVZP+tPA group receiving tPA (1.25 mg/kg, iv) 15 min before ventilation, HVZP group receiving HVZP+vehicle injection, and a control group receiving no ventilation. After 2 h of ventilation, the rats were killed; blood and lungs were collected for biochemical and histological analyses. RESULTS: HVZP ventilation significantly increased total protein content and the concentration of macrophage inflammatory protein-2 (MIP-2) in the bronchoalveolar lavage fluid (BALF) as well as the lung injury score. Rats that received HVZP ventilation had significantly higher lung PAI-1 mRNA expression, plasma PAI-1 and plasma D-dimer levels than the control animals. tPA treatment significantly reduced the BALF total protein and the lung injury score as compared to the HVZP group. tPA treatment also significantly decreased the plasma D-dimer levels and the HVZP ventilation-induced lung vascular fibrin thrombi. tPA treatment showed no effect on MIP-2 level in BALF. CONCLUSION: These results demonstrate that VILI increases lung PAI-1 mRNA expression, plasma levels of PAI-1 and D-dimers, lung injury score and vascular fibrin deposition. tPA can attenuate VILI by decreasing capillary-alveolar protein leakage as well as local and systemic coagulation as shown by decreased lung vascular fibrin deposition and plasma D-dimers.

Angiotensin II type 1 receptor antagonist attenuates lung fibrosis in hyperoxia-exposed newborn rats.

Bronchopulmonary dysplasia (BPD) remains a major cause of morbidity and mortality during the first year of life, and many infants have significant respiratory problems throughout childhood. Currently no effective therapy is clinically available to prevent the long-term pulmonary sequelae of BPD. Previous research has demonstrated that the renin-angiotensin system is up-regulated in human lung fibroblasts. Angiotensin II type 1 receptor (AT1R) antagonists and AT1R short interfering RNA diminished hyperoxia-increased collagen expression, whereas AT2R antagonists did not have any effects on these hyperoxia-induced changes. The in vivo therapeutic effects of AT1R antagonists on hyperoxia-induced lung fibrosis remain unknown. The present study assessed the effects of an AT1R antagonist (losartan) on preventing hyperoxia-induced lung fibrosis in newborn rats. Rat pups were exposed to 7 days of > 95% O2 and an additional 2 weeks of 60% O2. AT1R antagonist-treated pups were injected intraperitoneally with losartan at a dose of 10 mg/kg/day from postnatal days 1 to 7 and a dose of 5 mg/kg/day from postnatal days 8 to 21. Control group pups were injected with an equal volume of normal saline. AT1R antagonist treatment attenuated the hyperoxia-induced lung fibrosis on postnatal days 7 and 21 and also decreased the hyperoxia-induced expression of extracellular signal-regulated protein kinase and α-smooth muscle actin. AT1R antagonist treatment did not affect body weight or lung weight of the rats. These data suggest that AT1R antagonist may offer a novel therapeutic strategy for preventing hyperoxia-induced lung fibrosis.

Activation of the renin-angiotensin system in hyperoxia-induced lung fibrosis in neonatal rats.

BACKGROUND: Oxygen toxicity plays an important role in lung injury and may lead to bronchopulmonary dysplasia. We previously demonstrated that hyperoxia activated the renin-angiotensin system (RAS) in cultured human fetal lung fibroblasts. OBJECTIVE: To examine whether the upregulation of RAS components is associated with hyperoxia-induced lung fibrosis in neonatal Sprague-Dawley rats. METHODS: Experimental rat pups were exposed to 1 week of >95% O(2) and a further 2 weeks of 60% O(2). Control pups were exposed to room air over the same periods. Lung tissues were taken for biochemical and histochemical assays on postnatal days 7 and 21. RESULTS: Hyperoxia significantly increased total collagen content and the expression of type I collagen and alpha smooth muscle actin when compared to control rats. RAS components including angiotensinogen, angiotensin-converting enzyme, angiotensin II, and angiotensin II type 1 receptor were significantly upregulated by hyperoxia. The results also demonstrated that only the extracellular signal-regulated kinase (ERK) signaling pathway was activated by hyperoxia exposure. p38 mitogen-activated protein kinase and c-Jun N-terminal kinase were not activated. CONCLUSIONS: Local RAS activation is involved in the pathogenesis of hyperoxia-induced lung fibrosis in neonatal rats. ERK phosphorylation might mediate angiotensin II type 1 receptor activation.

Downregulation of caveolin-1 in a murine model of acute allergic airway disease.

BACKGROUND: Airway remodeling refers to the structural changes in the airways of asthma. Caveolin-1 reduces cell growth and negatively regulates smooth muscle cell proliferation. The aim was to investigate lung caveolin-1 status in a murine model of acute allergic airway disease. METHODS: Six- to eight-week-old female BALB/c mice were sensitized by intraperitoneal injections of phosphate-buffered saline or ovalbumin (OVA) and aluminium hydroxide on Days 0 and 14, challenged with aerosolized saline or OVA (1%) on Days 21-25, 28-32, and 35. The mice were killed 1 day after the last OVA/saline challenge. Serum OVA-specific immunoglobulin E (IgE) was measured by enzyme-linked immunosorbent assay. Peribronchial inflammation was quantified by morphometric analysis. Lung caveolin-1 and Type I collagen mRNA expression was determined by real-time reverse-transcription polymerase chain reaction. Total lung collagen was measured using Sircol Assay Kit. RESULTS: Serum OVA-specific IgE levels were significantly elevated in OVA-challenged mice when compared with saline-challenged mice. Percentage of inflammatory cells in the bronchoalveolar lavage was significantly higher in the OVA-challenged animals. The animals' lungs that were sensitized and challenged with OVA contained large numbers of inflammatory cells concentrated near the airways and in the perivascular areas. The thickness of the bronchial epithelial layer and smooth muscle layer and the numbers of total inflammatory cells and eosinophils significantly increased in OVA-challenged mice. Caveolin-1 mRNA expression significantly decreased and Type I collagen mRNA expression significantly increased in the lung tissue of OVA-challenged mice. CONCLUSION: These results suggest that caveolin-1 seems to be involved in the pathogenesis of airway remodeling of acute allergic airway disease.

Maternal baicalin treatment increases fetal lung surfactant phospholipids in rats.

Baicalin is a flavonoid compound purified from the medicinal plant Scutellaria baicalensis Georgi and has been reported to stimulate surfactant protein (SP)-A gene expression in human lung epithelial cell lines (H441). The aims of this study were to determine whether maternal baicalin treatment could increase lung surfactant production and induce lung maturation in fetal rats. This study was performed with timed pregnant Sprague-Dawley rats. One-day baicalin group mothers were injected intraperitoneally with baicalin (5 mg/kg/day) on Day 18 of gestation. Two-day baicalin group mothers were injected intraperitoneally with baicalin (5 mg/kg/day) on Days 17 and 18 of gestation. Control group mothers were injected with vehicle alone on Day 18 of gestation. On Day 19 of gestation, fetuses were delivered by cesarean section. Maternal treatment with 2-day baicalin significantly increased saturated phospholipid when compared with control group and total phospholipid in fetal lung tissue when compared with control and 1-day baicalin groups. Antenatal treatment with 2-day baicalin significantly increased maternal growth hormone when compared with control group. Fetal lung SP-A mRNA expression and maternal serum corticosterone levels were comparable among the three experimental groups. Maternal baicalin treatment increases pulmonary surfactant phospholipids of fetal rat lungs and the improvement was associated with increased maternal serum growth hormone. These results suggest that antenatal baicalin treatment might accelerate fetal rat lung maturation.

The renin-angiotensin system mediates hyperoxia-induced collagen production in human lung fibroblasts.

A high concentration of oxygen can cause lung injury and lead to pulmonary fibrosis. Angiotensin (Ang) II induces human lung fibroblast proliferation and stimulates collagen synthesis. However, the role of the renin-angiotensin system (RAS) in the pathogenesis of hyperoxia-induced collagen production is unclear. The aims of this study were to investigate the effects of hyperoxia on the components of the RAS and collagen expression in human lung fibroblasts (MRC-5). Hyperoxia increased total collagen, collagen type I, and alpha-smooth muscle actin (alpha-SMA) mRNA and protein expression. RAS components and Ang II production were also significantly increased after hyperoxic exposure. Hyperoxia induced Ang II type 1 receptor (AT1R) expression but did not alter AT2R expression, furthermore, silencing of AT1R signaling with small interfering RNA suppressed hyperoxia-induced phosphorylated-ERK (p-ERK) 1/2, alpha-SMA, and collagen type I expression. Ang II increased p-ERK 1/2 and collagen type I expression, and these increases were inhibited by the AT1R inhibitor, losartan, but not by the AT2R inhibitor, PD123319 under both normoxic and hyperoxic conditions. These data suggest Ang II-mediated signaling transduction via AT1R is involved in hyperoxia-induced collagen synthesis in human lung fibroblasts.