Contribution of alveolar type II cell-derived cyclooxygenase-2 to basal airway function, lung inflammation, and lung fibrosis

Effects of sEH inhibition on the eicosanoid and cytokine storms in SARS-CoV-2-infected mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection involves an initial viral infection phase followed by a host-response phase that includes an eicosanoid and cytokine storm, lung inflammation and respiratory failure. While vaccination and early anti-viral therapies are effective in preventing or limiting the pathogenic host response, this latter phase is poorly understood with no highly effective treatment options. Inhibitors of soluble epoxide hydrolase (sEH) increase levels of anti-inflammatory molecules called epoxyeicosatrienoic acids (EETs). This study aimed to investigate the impact of sEH inhibition on the host response to SARS-CoV-2 infection in a mouse model with human angiotensin-converting enzyme 2 (ACE2) expression. Mice were infected with SARS-CoV-2 and treated with either vehicle or the sEH inhibitor 1-trifluoromethoxyphenyl-3-(1-propionylpiperidin-4-yl) urea (TPPU). At day 5 post-infection, SARS-CoV-2 induced weight loss, clinical signs, a cytokine storm, an eicosanoid storm, and severe lung inflammation with ~50% mortality on days 6-8 post-infection. SARS-CoV-2 infection induced lung expression of phospholipase A2 (PLA2), cyclooxygenase (COX) and lipoxygenase (LOX) pathway genes, while suppressing expression of most cytochrome P450 genes. Treatment with the sEH inhibitor TPPU delayed weight loss but did not alter clinical signs, lung cytokine expression or overall survival of infected mice. Interestingly, TPPU treatment significantly reversed the eicosanoid storm and attenuated viral-induced elevation of 39 fatty acids and oxylipins from COX, LOX and P450 pathways, which suggests the effects at the level of PLA2 activation. The suppression of the eicosanoid storm by TPPU without corresponding changes in lung cytokines, lung inflammation or mortality reveals a surprising dissociation between systemic oxylipin and cytokine signaling pathways during SARS-CoV-2 infection and suggests that the cytokine storm is primarily responsible for morbidity and mortality in this animal model.

Zingiber officinale-Derived Extracellular Vesicles Attenuate Bleomycin-Induced Pulmonary Fibrosis Trough Antioxidant, Anti-Inflammatory and Protease Activity in a Mouse Model

Idiopathic pulmonary fibrosis (IPF) is the most frequent and severe idiopathic interstitial pneumonia. It is a chronic and progressive disease with a poor prognosis and is a major cause of morbidity and mortality. This disease has no cure; therefore, there is a clinical need to search for alternative treatments with greater efficacy. In this study, we aimed to evaluate the effect of extracellular vesicles (EVs) from Zingiber officinale (EVZO) in a murine model of bleomycin (BLM)-induced IPF administered through an osmotic minipump. EVZO had an average size of 373 nm and a spherical morphology, as identified by scanning electron microscopy. Label-free proteomic analysis of EVZOs was performed by liquid chromatography coupled to mass spectrometry, and 20 proteins were identified. In addition, we demonstrated the protease activity of EVZO by gelatin-degrading zymography assay and the superoxide dismutase (SOD) activity of EVZO by an enzymatic assay. In the BLM-induced IPF mouse model, nasal administration of 50 μg of EVZO induced recovery of alveolar space size and decreased cellular infiltrate, collagen deposition, and expression of α-SMA-positive cells. Additionally, EVZO inhibited inflammatory markers such as iNOS and COX-2, lipid peroxidation, and apoptotic cells. These results show that EVZO may represent a novel natural delivery mechanism to treat IPF.

Unravelling the Therapeutic Potential of Nano-Delivered Functional Foods in Chronic Respiratory Diseases

Chronic inflammation of the respiratory tract is one of the most concerning public health issues, as it can lead to chronic respiratory diseases (CRDs), some of which are more detrimental than others. Chronic respiratory diseases include chronic obstructive pulmonary disease (COPD), asthma, lung cancer, and pulmonary fibrosis. The conventional drug therapies for the management and treatment of CRDs only address the symptoms and fail to reverse or recover the chronic-inflammation-mediated structural and functional damage of the respiratory tract. In addition, the low efficacy and adverse effects of these drugs have directed the attention of researchers towards nutraceuticals in search of potential treatment strategies that can not only ameliorate CRD symptoms but also can repair and reverse inflammatory damage. Hence, there is a growing interest toward investigating the medicinal benefits of nutraceuticals, such as rutin, curcumin, zerumbone, and others. Nutraceuticals carry many nutritional and therapeutic properties, including anti-inflammatory, antioxidant, anticancer, antidiabetic, and anti-obesity properties, and usually do not have as many adverse effects, as they are naturally sourced. Recently, the use of nanoparticles has also been increasingly studied for the nano drug delivery of these nutraceuticals. The discrete size of nanoparticles holds great potential for the level of permeability that can be achieved when transporting these nutraceutical compounds. This review is aimed to provide an understanding of the use of nutraceuticals in combination with nanoparticles against CRDs and their mechanisms involved in slowing down or reversing the progression of CRDs by inhibiting pro-inflammatory signaling pathways.

Vitamin E relieves chronic obstructive pulmonary disease by inhibiting COX2-mediated p-STAT3 nuclear translocation through the EGFR/MAPK signaling pathway

Patients with chronic obstructive pulmonary disease (COPD) are characterized by an imbalance between oxidant enzymes and antioxidant enzymes. In the present study, we explored the protective effect of vitamin E on COPD and the underlying mechanisms. Targets of vitamin E were predicted by bioinformatics analysis. After establishing cigarette smoke (CS)-induced COPD rats, the expression levels of epidermal growth factor receptor (EGFR), cyclooxygenase 2 (COX2), and transcriptional activity of signal transducer and activator of transcription 3 (STAT3) were measured. Additionally, the effects of vitamin E on CS-induced COPD were explored by assessing inflammation, the reactive oxygen species (ROS), the activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA), viability of human bronchial epithelioid (HBE) cells, and the expression of EGFR/MAPK pathway-related factors after loss- and gain- function assays. Vitamin E alleviated COPD. Vitamin E inhibited MAPK signaling pathway through decreasing EGFR expression. Additionally, vitamin E suppressed CS-induced HBE cell damage. Functionally, vitamin E attenuated CS-induced inflammation, apoptosis, and ROS by inhibiting the EGFR/MAPK axis, thereby inhibiting COX2-mediated p-STAT3 nuclear translocation. Moreover, overexpression of COX2 attenuated the protective effect of vitamin E on COPD rats. The present study shows that vitamin E inhibits the expression of COX2 by negatively regulating the EGFR/MAPK pathway, thereby inhibiting the translocation of phosphorylated STAT3 to the nucleus and relieving COPD.

Poldip2/Nox4 Mediates Lipopolysaccharide-Induced Oxidative Stress and Inflammation in Human Lung Epithelial Cells

NADPH oxidase 4 (Nox4) is an important source of reactive oxygen species (ROS) production, and its expression is increased in lipopolysaccharide- (LPS-) stimulated lung epithelial cells. Polymerase δ-interacting protein 2 (Poldip2) has been proved to bind Nox4 and participates in oxidative stress and inflammation. However, the role of Poldip2/Nox4 in LPS-induced oxidative stress and inflammation in lung epithelial cells remains unclear. Cell viability was measured via MTT assays. The expression of Poldip2, Nox4, heme oxygenase-1 (HO-1), cyclooxygenase-2 (COX-2), AKT, and p-AKT was detected by Western blotting and/or immunofluorescence. Poldip2 and Nox4 interaction was analyzed via coimmunoprecipitation (Co-IP) assay. NADPH enzymatic activity and production of ROS, prostaglandin E2 (PGE2), tumor necrosis factor-α (TNF-α), and interleukin-1β (IL-1β) were assessed simultaneously. The small interfering RNA (siRNA) or plasmid targeting Nox4 was used to downregulate or upregulate Nox4, and the lentiviral vector encoding Poldip2 was used to downregulate or upregulate Poldip2. The present study demonstrated that LPS stimulation significantly increased the protein levels of Poldip2 and Nox4 and proved that Poldip2 interacted with Nox4 proved by Co-IP. Importantly, Poldip2 acted as an upstream regulator of Nox4. The increased expression of Nox4 and COX-2; NADPH enzymatic activity; production of ROS, PGE2, TNF-α, and IL-1β; and decreased HO-1 expression were significantly suppressed by lentiviral Poldip2 shRNA downregulation but were increased by lentiviral upregulation of Poldip2. Furthermore, inhibiting of PI3K-AKT signaling notably attenuated LPS-induced Poldip2/Nox4 activation. Our study demonstrated that Poldip2 mediates LPS-induced oxidative stress and inflammation via interaction with Nox4 and was regulated by the PI3K-AKT signaling. Targeting Poldip2 could be a beneficial therapeutic strategy for the treatment of ALI.

Network pharmacology-based strategy to investigate the active ingredients and molecular mechanisms of Scutellaria Barbata D. Don against radiation pneumonitis

INTRODUCTION

Herbal medicines combined with radiotherapy significantly reduced the incidence of radiation pneumonitis (RP), and the Scutellaria barbata D. Don (SBD) is a perennial herb that has been reported to protect against radiation-induced pneumonitis. However, the exact molecular mechanism is not known. The objective of this research was to investigate the against radiation pneumonitis ingredients and their functional mechanisms in SBD.

METHODS

Based on the network pharmacology approaches, we collected active ingredients and target genes in SBD against RP through Traditional Chinese Medicine System Pharmacology (TCMSP) Database, and the "Herb-Ingredients-Target Genes-Disease" Network was constructed by using of Cytoscape. STRING analysis was performed to reveal the protein-protein interactions, and then we applied enrichment analysis on these target proteins, gene function, and pathways.

RESULTS

A total of 18 ingredients in SBD regulate 65 RP related target proteins, which show that quercetin, luteolin, baicalein, wogonin may be the key active ingredients, while IL6, AKT1, VEGFA, MMP9, CCL2, prostaglandin-endoperoxide synthase 2 (PTGS2) (cyclooxygenase-2 [COX-2]), CXCL8, IL1B, mitogen-activated protein kinase (MAPK1), and IL10 were identified as critical targets. Besides, the results of Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that predicted targets of SBD are mostly associated with the pathological process of oxidative stress and inflammation. AGE- Receptor of Advanced Glycation Endproducts (RAGE) signaling pathway in diabetic complications, IL-17 signaling pathway, hypoxia-inducible factor-1 (HIF-1) signaling pathway, NF-kappa B signaling pathway might serve as the principal pathways for RP treatment.

CONCLUSION

In our study, the pharmacological and molecular mechanism of SBD against RP was predicted from a holistic perspective, and the results provided theoretical guidance for researchers to explore the mechanism in further research.

Mesenchymal Stem Cell-Derived Exosomes Ameliorate Dermal Fibrosis in a Murine Model of Bleomycin-Induced Scleroderma

Mesenchymal stem cells (MSCs) have become a promising therapeutic strategy for scleroderma. Exosomes derived from MSCs (MSC-exosomes) possess functional properties similar to those of their source cells. In this study, we aimed to explore the potential role of MSC-exosomes in the treatment of scleroderma. MSC-exosomes were isolated from human umbilical cords through ultracentrifugation and characterized. An experimental fibrosis model was established in BALB/c mice by a subcutaneous injection of bleomycin, followed by treatment with MSC-exosomes or MSC infusions once a week for a total of four doses. Using hematoxylin and eosin and Masson's trichrome staining and immunohistochemistry, hydroxyproline content, and quantitative real-time polymerase chain reaction analyses, we investigated the effects of MSC-exosomes on dermal fibrosis and explored the underlying mechanism. MSC-exosome treatment restored the dermal architecture, reduced dermal thickness, and partially increased subcutaneous adipose tissue thickness. In addition, MSC-exosomes inhibited the expression of collagen (COL)-I, COL-III, and α-smooth muscle actin. The transforming growth factor (TGF)-β/Smad signaling pathway was also suppressed in MSC-exosome-treated mice. Taken together, our results suggest that MSC-exosomes can attenuate myofibroblast activation and collagen deposition in dermal fibrosis by downregulating the TGF-β/Smad signaling pathway. Therefore, the use of MSC-exosomes may be a potential therapeutic approach for the treatment of scleroderma.

DNA Methylation in Pulmonary Fibrosis

DNA methylations, including global methylation pattern and specific gene methylation, are associated with pathogenesis and progress of pulmonary fibrosis. This chapter illustrates alteration of DNA methylation in pulmonary fibrosis as a predictive or prognostic factor. Treatment with the DNA methylation inhibitors will be an emerging anti-fibrosis therapy, although we are still in the pre-clinical stage of using epigenetic markers as potential targets for biomarkers and therapeutic interventions.

Natural Sesquiterpene Lactones in the Prevention and Treatment of Inflammatory Disorders and cancer: A Systematic Study of this Emerging Therapeutic Approach based on Chemical and Pharmacological Aspect

Background and Introduction:

Sesquiterpene lactones are a class of secondary metabolite that contains sesquiterpenoids and lactone ring as pharmacophore moiety. A large group of bioactive secondary metabolites such as phytopharmaceuticals belong to this category. From the Asteraceae family-based medicinal plants, more than 5,000 sesquiterpene lactones have been reported so far. Sesquiterpene lactone-based pharmacophore moieties hold promise for broad-spectrum biological activities against cancer, inflammation, parasitic, bacterial, fungal, viral infection and other functional disorders. Moreover, these moiety based phytocompounds have been highlighted with a new dimension in the natural drug discovery program worldwide after the 2015 Medicine Nobel Prize achieved by the Artemisinin researchers.

Objective:

These bitter substances often contain an α, β-unsaturated-γ-lactone as a major structural backbone, which in recent studies has been explored to be associated with anti-tumor, cytotoxic, and anti-inflammatory action. Recently, the use of sesquiterpene lactones as phytomedicine has been increased. This study will review the prospect of sesquiterpene lactones against inflammation and cancer.

Methods:

Hence, we emphasized on the different features of this moiety by incorporating its structural diversity on biological activities to explore structure-activity relationships (SAR) against inflammation and cancer.

Results:

How the dual mode of action such as anti-inflammatory and anti-cancer has been exhibitedby these phytopharmaceuticals will be forecasted in this study. Furthermore, the correlation of anti-inflammatory and anti-cancer activity executed by the sesquiterpene lactones for fruitful phytotherapy will also be revealed in the present review in the milieu of pharmacophore activity relation and pharmacodynamics study as well.

Conclusion:

So, these metabolites are paramount in phytopharmacological aspects. The present discussion on the future prospect of this moiety based on the reported literature could be a guide for anti-inflammatory and anti-cancer drug discovery programs for the upcoming researchers.

Exosomes: Carriers of Pro-Fibrotic Signals and Therapeutic Targets in Fibrosis

Exosomes are nano-sized extracellular vesicles that are released by a variety of cells. Exosomes contain cargo from cells they derived, including lipids, proteins and nucleic acids. The bilayer lipid membrane structure of exosomes protects these contents from degradation, allowing them for intercellular communication. The role of exosomes in fibrotic diseases is increasingly being valued. Exosomes, as carriers of profibrotic signals, are involved in the development of fibrotic diseases, and also regulate fibrosis by transmitting signals that inhibit fibrosis or inflammation. Exosomes mobilize and activate a range of effector cells by targeted delivery of bioactive information. Exosomes can also reflect the condition of cells, tissues and organisms, and thus become potential biomarkers of fibrotic diseases. Exosomes from bone marrow stem cells support biological signaling that regulates and inhibits fibrosis and thus initially used in the treatment of fibrotic diseases. This article briefly summarizes the role of exosomes in the pathogenesis and treatment of fibrotic diseases and raises some issues that remain to be resolved.

Inhibiting eicosanoid degradation exerts antifibrotic effects in a pulmonary fibrosis mouse model and human tissue

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a disease with high 5-year mortality and few therapeutic options. Prostaglandin (PG) E₂ exhibits antifibrotic properties and is reduced in bronchoalveolar lavage from patients with IPF. 15-Prostaglandin dehydrogenase (15-PGDH) is the key enzyme in PGE₂ metabolism under the control of TGF-β and microRNA 218.

OBJECTIVE

We sought to investigate the expression of 15-PGDH in IPF and the therapeutic potential of a specific inhibitor of this enzyme in a mouse model and human tissue.

METHODS

In vitro studies, including fibrocyte differentiation, regulation of 15-PGDH, RT-PCR, and Western blot, were performed using peripheral blood from healthy donors and patients with IPF and A549 cells. Immunohistochemistry, immunofluorescence, 15-PGDH activity assays, and in situ hybridization as well as ex vivo IPF tissue culture experiments were done using healthy donor and IPF lungs. Therapeutic effects of 15-PGDH inhibition were studied in the bleomycin mouse model of pulmonary fibrosis.

RESULTS

We demonstrate that 15-PGDH shows areas of increased expression in patients with IPF. Inhibition of this enzyme increases PGE₂ levels and reduces collagen production in IPF precision cut lung slices and in the bleomycin model. Inhibitor-treated mice show amelioration of lung function, decreased alveolar epithelial cell apoptosis, and fibroblast proliferation. Pulmonary fibrocyte accumulation is also decreased by inhibitor treatment in mice, similar to PGE₂ that inhibits fibrocyte differentiation from blood of healthy donors and patients with IPF. Finally, microRNA 218-5p, which is downregulated in patients with IPF, suppressed 15-PGDH expression in vivo and in vitro.

CONCLUSIONS

These findings highlight the role of 15-PGDH in IPF and suggest 15-PGDH inhibition as a promising therapeutic approach.

Novel insights into the role of LRRC8A in ameliorating alveolar fluid clearance in LPS induced acute lung injury

Leucine-rich repeat-containing 8A (LRRC8A) protein was recently identified as an essential component of volume-regulated anion channel which plays a central role in maintaining cell volume. The aim of this study was to elucidate the role of LRRC8A in alveolar fluid clearance (AFC) and the effect of inflammatory cytokines on LRRC8A and the underlying mechanism. Lipopolysaccharide (LPS) was used to generate a rat acute lung injury model. The results showed that the concentrations of IL-1β, TNF-α and IL-6 in bronchoalveolar lavage fluid increased significantly, but the expression of LRRC8A in the lung tissue decreased dramatically in the acute lung injury group followed by a decline in the AFC rate. Additionally, LRRC8A knockdown reduced AFC in normal rats. However, specific overexpression of LRRC8A in the lung could increase AFC. Furthermore, we observed the effects of LPS, IL-1β, TNF-α and IL-6 on the LRRC8A current in alveolar type II (ATII) cells, and IL-1β showed the greatest inhibition among them, which was involved in phospho-p38 activation. Overall, LRRC8A plays an essential role in the progression of AFC in LPS-induced acute lung injury, and chronic treatment with IL-1β or TNF-α could inhibit the function of LRRC8A in ATII cells by targeting phospho-p38. All of the findings suggested that LRRC8A could be a new partner in AFC and a potential target for the treatment of acute lung injury.

Zinc and iron complexes of oleanolic acid, (OA) attenuate allergic airway inflammation in rats

Oleanolic acid (OA) is a hydroxyl pentacyclic triterpene acid (HTAs) used in various ailments. Inflammatory diseases may be profoundly influenced by iron (Fe) and zinc (Zn) status. We studied the anti-asthmatic effects of two metal complexes (Fe and Zn) of OA in the ovalbumin (OVA)-induced rat model. Delayed type hypersensitivity (DTH) was measured. Total and differential leucocyte count was done in blood as well as bronchoalveolar lavage fluid (BALF). The mRNA expression levels of pro-inflammatory cytokines were measured in lung tissue by reverse transcription polymerase chain reaction. The levels of cyclooxygenase-2 (COX-2), immunoglobulin E (IgE) and 5-lipoxygenase (5-LOX) were estimated by enzyme linked immunosorbent assay. Splenocyte proliferation was performed through BrdU uptake method and nitric oxide levels were measured by colorimetric assay kit. The acute toxicity study was also done for the complexes. The asthmatic group developed allergic airway inflammation shown by increased DTH and inflammatory markers in blood and BALF. OA + Fe and OA + Zn displayed significant decrease in DTH, NO, expression of IL-4, 5, 13, 17, toll-like receptor-2, nuclear factor-kappa B and tumor necrosis factor-α; serum IgE, COX-2, and 5-LOX. The metal complexes also attenuated OVA-stimulated splenocyte proliferation. While no hepatotoxic or nephrotoxic potential was shown by OA + Fe and OA + Zn. Our findings indicate that both OA + Fe and OA + Zn possess significant anti-asthmatic effect which may be ascribed to its immunomodulatory and anti-inflammatory features.

Protective Role of Surfactant Protein-D Against Lung Injury and Oxidative Stress Induced by Nitrogen Mustard

Nitrogen mustard (NM) is a vesicant known to cause acute pulmonary injury which progresses to fibrosis. Macrophages contribute to both of these pathologies. Surfactant protein (SP)-D is a pulmonary collectin that suppresses lung macrophage activity. Herein, we analyzed the effects of loss of SP-D on NM-induced macrophage activation and lung toxicity. Wild-type (WT) and SP-D-/- mice were treated intratracheally with PBS or NM (0.08 mg/kg). Bronchoalveolar lavage (BAL) fluid and tissue were collected 14 days later. In WT mice, NM caused an increase in total SP-D levels in BAL; multiple lower molecular weight forms of SP-D were also identified, consistent with lung injury and oxidative stress. Flow cytometric analysis of BAL cells from NM treated WT mice revealed the presence of proinflammatory and anti-inflammatory macrophages. Whereas loss of SP-D had no effect on numbers of these cells, their activation state, as measured by proinflammatory (iNOS, MMP-9), and anti-inflammatory (MR-1, Ym-1) protein expression, was amplified. Loss of SP-D also exacerbated NM-induced oxidative stress and alveolar epithelial injury, as reflected by increases in heme oxygenase-1 expression, and BAL cell and protein content. This was correlated with alterations in pulmonary mechanics. In NM-treated SP-D-/-, but not WT mice, there was evidence of edema, epithelial hypertrophy and hyperplasia, bronchiectasis, and fibrosis, as well as increases in BAL phospholipid content. These data demonstrate that activated lung macrophages play a role in NM-induced lung injury and oxidative stress. Elucidating mechanisms regulating macrophage activity may be important in developing therapeutics to treat mustard-induced lung injury.

The PGI2 Analog Cicaprost Inhibits IL-33-Induced Th2 Responses, IL-2 Production, and CD25 Expression in Mouse CD4+ T Cells

IL-33 has pleiotropic functions in immune responses and promotes the development of allergic diseases and asthma. IL-33 induces Th2 differentiation and enhances type 2 cytokine production by CD4⁺ T cells. However, the regulation of IL-33-driven type 2 cytokine responses is not fully defined. In this study, we investigated the effect of PGI₂, a lipid mediator formed in the cyclooxygenase pathway of arachidonic acid metabolism, on naive CD4⁺ T cell activation, proliferation, and differentiation by IL-33. Using wild-type and PGI₂ receptor (IP) knockout mice, we found that the PGI₂ analog cicaprost dose-dependently inhibited IL-33-driven IL-4, IL-5, and IL-13 production by CD4⁺ T cells in an IP-specific manner. In addition, cicaprost inhibited IL-33-driven IL-2 production and CD25 expression by CD4⁺ T cells. Furthermore, IP knockout mice had increased IL-5 and IL-13 responses of CD4⁺ T cells to Alternaria sensitization and challenge in mouse lungs. Because IL-33 is critical for Alternaria-induced type 2 responses, these data suggest that PGI₂ not only inhibits IL-33-stimulated CD4⁺ Th2 cell responses in vitro but also suppresses IL-33-induced Th2 responses caused by protease-containing allergens in vivo.

Methods and practices to diversify cell-based products

Medicinal signaling cell (MSC)-based products represent emerging treatments in various therapeutic areas including cardiometabolic, inflammation, autoimmunity, orthopedics, wound healing and oncology. Exploring innovation beyond minimally manipulated plastic-adherent ex vivo expanded allogeneic MSCs enables product delineation. Product delineation is on the critical path to maximize clinical benefits and market access. An innovation framework is presented here along various innovation dimensions comprising composition-of-matter by means of positive cell surface markers, formulation varying for example the cell dose or the preservation mode and medium, manufacturing to adapt the secretome of MSCs to the condition of interest, the mode of delivery and corresponding delivery devices, as well as molecular engineering and biomarkers. The rationale of the innovation space thus described applies generally to all cell-based therapies.

Niacin ameliorates ulcerative colitis via prostaglandin D2-mediated D prostanoid receptor 1 activation

Niacin, as an antidyslipidemic drug, elicits a strong flushing response by release of prostaglandin (PG) D₂. However, whether niacin is beneficial for inflammatory bowel disease (IBD) remains unclear. Here, we observed niacin administration‐enhanced PGD₂ production in colon tissues in dextran sulfate sodium (DSS)‐challenged mice, and protected mice against DSS or 2,4,6‐trinitrobenzene sulfonic acid (TNBS)‐induced colitis in D prostanoid receptor 1 (DP1)‐dependent manner. Specific ablation of DP1 receptor in vascular endothelial cells, colonic epithelium, and myeloid cells augmented DSS/TNBS‐induced colitis in mice through increasing vascular permeability, promoting apoptosis of epithelial cells, and stimulating pro‐inflammatory cytokine secretion of macrophages, respectively. Niacin treatment improved vascular permeability, reduced apoptotic epithelial cells, promoted epithelial cell update, and suppressed pro‐inflammatory gene expression of macrophages. Moreover, treatment with niacin‐containing retention enema effectively promoted UC clinical remission and mucosal healing in patients with moderately active disease. Therefore, niacin displayed multiple beneficial effects on DSS/TNBS‐induced colitis in mice by activation of PGD₂/DP1 axis. The potential efficacy of niacin in management of IBD warrants further investigation.

The Role of PGE2 in Alveolar Epithelial and Lung Microvascular Endothelial Crosstalk

Disruption of the blood-air barrier, which is formed by lung microvascular endothelial and alveolar epithelial cells, is a hallmark of acute lung injury. It was shown that alveolar epithelial cells release an unidentified soluble factor that enhances the barrier function of lung microvascular endothelial cells. In this study we reveal that primarily prostaglandin (PG) E₂ accounts for this endothelial barrier-promoting activity. Conditioned media from alveolar epithelial cells (primary ATI-like cells) collected from BALB/c mice and A549 cells increased the electrical resistance of pulmonary human microvascular endothelial cells, respectively. This effect was reversed by pretreating alveolar epithelial cells with a cyclooxygenase-2 inhibitor or by blockade of EP4 receptors on endothelial cells, and in A549 cells also by blocking the sphingosine-1-phosphate₁ receptor. Cyclooxygenase-2 was constitutively expressed in A549 cells and in primary ATI-like cells, and was upregulated by lipopolysaccharide treatment. This was accompanied by enhanced PGE₂ secretion into conditioned media. Therefore, we conclude that epithelium-derived PGE₂ is a key regulator of endothelial barrier integrity via EP4 receptors under physiologic and inflammatory conditions. Given that pharmacologic treatment options are still unavailable for diseases with compromised air-blood barrier, like acute lung injury, our data thus support the therapeutic potential of selective EP4 receptor agonists.

Nuclear factor-kappa B influences early phase of compensatory lung growth after pneumonectomy in mice

Background

Compensatory lung growth (CLG) is a well-established lung regeneration model. However, the sequential mechanisms, including unknown molecular triggers or regulators, remain unclear. Nuclear factor- kappa B (NF-κB) is known to be essential for inflammation and tissue regeneration; therefore, we investigated the role of NF-κB in CLG.

Methods

C57BL/6 J mice underwent either a left pneumonectomy or a thoracotomy (n = 77). Gene microarray analysis was performed to detect genes that were upregulated at 12 h after pneumonectomy. NF-κB protein expression was examined by immunohistochemistry and Western blot. To investigate the influence of NF-κB on CLG, either an NF-κB inhibitor SN50 or saline was administered following pneumonectomy and the degree of CLG was evaluated in each group by measuring the lung dry weight index (LDWI) and the mean linear intercept.

Results

Gene microarray analysis identified 11 genes that were significantly but transiently increased at 12 h after pneumonectomy. Among the 11 genes, NF-κB was selected based on its reported functions. Western blot analysis showed that NF-κB protein expression after pneumonectomy was significantly higher at 12 h compared to 48 h. Additionally, NF-κB protein expression at 12 h after pneumonectomy was significantly higher than at both 12 and 48 h after thoracotomy (p < 0.029 for all). NF-κB protein expression, evaluated through immunohistochemistry, was expressed mainly in type 2 alveolar epithelial cells and was significant increased 12 h after pneumonectomy compared to 48 h after pneumonectomy and both 12 and 48 h after thoracotomy (p < 0.001 for all). SN50 administration following pneumonectomy induced a significant decrease in NF-κB expression (p = 0.004) and LDWI compared to the vehicle administration (p = 0.009).

Conclusions

This is the first report demonstrating that NF-κB signaling may play a key role in CLG. Given its pathway is crucial in tissue regeneration of various organs, NF-κB may shed light on identification of molecular triggers or clinically usable key regulators of CLG.

Parecoxib reduced ventilation induced lung injury in acute respiratory distress syndrome

Background

Cyclooxygenase-2 (COX-2) contributes to ventilation induced lung injury (VILI) and acute respiratory distress syndrome (ARDS). The objective of present study was to observe the therapeutic effect of parecoxib on VILI in ARDS.

Methods

In this parallel controlled study performed at Harbin Medical University, China between January 2016 and March 2016, 24 rats were randomly allocated into sham group (S), volume ventilation group/ARDS (VA), parecoxib/volume ventilation group/ARDS (PVA). Rats in the S group only received anesthesia; rats in the VA and PVA group received intravenous injection of endotoxin to induce ARDS, and then received ventilation. Rats in the VA and PVA groups were treated with intravenous injection of saline or parecoxib. The ratio of arterial oxygen pressure to fractional inspired oxygen (PaO₂/FiO₂), the wet to dry weight ratio of lung tissue, inflammatory factors in serum and bronchoalveolar lavage fluid (BALF), and histopathologic analyses of lung tissue were examined. In addition, survival was calculated at 24 h after VILI.

Results

Compared to the VA group, in the PVA group, PaO₂/FiO₂ was significantly increased; lung tissue wet to dry weight ratio; macrophage and neutrophil counts, total protein and neutrophil elastase levels in BALF; tumor necrosis factor-α, interleukin-1β, and prostaglandin E₂ levels in BALF and serum; and myeloperoxidase (MPO) activity, malondialdehyde levels, and Bax and COX-2 protein levels in lung tissue were significantly decreased, while Bcl-2 protein levels were significantly increased. Lung histopathogical changes and apoptosis were reduced by parecpxib in the PVA group. Survival was increased in the PVA group.

Conclusions

Parecoxib improves gas exchange and epithelial permeability, decreases edema, reduces local and systemic inflammation, ameliorates lung injury and apoptosis, and increases survival in a rat model of VILI.

World Trade Center (WTC) dust exposure in mice is associated with inflammation, oxidative stress and epigenetic changes in the lung

Exposure to World Trade Center (WTC) dust has been linked to respiratory disease in humans. In the present studies we developed a rodent model of WTC dust exposure to analyze lung oxidative stress and inflammation, with the goal of elucidating potential epigenetic mechanisms underlying these responses. Exposure of mice to WTC dust (20μg, i.t.) was associated with upregulation of heme oxygenase-1 and cyclooxygenase-2 within 3days, a response which persisted for at least 21days. Whereas matrix metalloproteinase was upregulated 7days post-WTC dust exposure, IL-6RA1 was increased at 21days; conversely, expression of mannose receptor, a scavenger receptor important in particle clearance, decreased. After WTC dust exposure, increases in methylation of histone H3 lysine K4 at 3days, lysine K27 at 7days and lysine K36, were observed in the lung, along with hypermethylation of Line-1 element at 21days. Alterations in pulmonary mechanics were also observed following WTC dust exposure. Thus, 3days post-exposure, lung resistance and tissue damping were decreased. In contrast at 21days, lung resistance, central airway resistance, tissue damping and tissue elastance were increased. These data demonstrate that WTC dust-induced inflammation and oxidative stress are associated with epigenetic modifications in the lung and altered pulmonary mechanics. These changes may contribute to the development of WTC dust pathologies.