Anti-Inflammatory Effects of OxPAPC Involve Endothelial Cell-Mediated Generation of LXA4

OxPAPC stabilizes liquid-ordered domains in biomimetic membranes

Long-chain polyunsaturated fatty acids (PUFAs) are prone to nonenzymatic oxidation in response to differing environmental stressors and endogenous cellular sources. There is increasing evidence that phospholipids containing oxidized PUFA acyl chains control the inflammatory response. However, the underlying mechanism(s) of action by which oxidized PUFAs exert their functional effects remain unclear. Herein, we tested the hypothesis that replacement of 1-palmitoyl-2-arachidonyl-phosphatidylcholine (PAPC) with oxidized 1-palmitoyl-2-arachidonyl-phosphatidylcholine (oxPAPC) regulates membrane architecture. Specifically, with solid-state 2H NMR of biomimetic membranes, we investigated how substituting oxPAPC for PAPC modulates the molecular organization of liquid-ordered (Lo) domains. 2H NMR spectra for bilayer mixtures of 1,2-dipalmitoylphosphatidylcholine-d62 (an analog of DPPC deuterated throughout sn-1 and -2 chains) and cholesterol to which PAPC or oxPAPC was added revealed that replacing PAPC with oxPAPC disrupted molecular organization, indicating that oxPAPC does not mix favorably in a tightly packed Lo phase. Furthermore, unlike PAPC, adding oxPAPC stabilized 1,2-dipalmitoylphosphatidylcholine-d6-rich/cholesterol-rich Lo domains formed in mixtures with 1,2-dioleoylphosphatidylcholine while decreasing the molecular order within 1,2-dioleoylphosphatidylcholine-rich liquid-disordered regions of the membrane. Collectively, these results suggest a mechanism in which oxPAPC stabilizes Lo domains-by disordering the surrounding liquid-disordered region. Changes in the structure, and thereby functionality, of Lo domains may underly regulation of plasma membrane-based inflammatory signaling by oxPAPC.

Lipoxin A4 methyl ester attenuated ketamine-induced neurotoxicity in SH-SY5Y cells via regulating leptin pathway

Ketamine, the widely used intravenous anesthetic, has been reported to cause neurotoxicity and disturbs normal neurogenesis. However, the efficacy of current treatment strategies targeting ketamine's neurotoxicity remains limited. Lipoxin A4 methyl ester (LXA4 ME) is relatively stable lipoxin analog, which serves an important role in protecting against early brain injury. The purpose of this study was to investigate the protective effect of LXA4 ME on ketamine-caused cytotoxicity in SH-SY5Y cells, as well as the underlying mechanisms. Cell viability, apoptosis and endoplasmic reticulum stress (ER stress) were detected by adopting experimental techniques including CCK-8 assay, flow cytometry, western blotting and transmission electron microscope. Furthermore, examining the expression of leptin and its receptor (LepRb), we also measured the levels of activation of the leptin signaling pathway. Our results showed that LXA4 ME intervention promoted the cell viability, inhibited cell apoptosis, and reduced the expression of ER stress related protein and morphological changes induced by ketamine. In addition, inhibition of leptin signaling pathway caused by ketamine could be reversed by LXA4 ME. However, as the specific inhibitor of leptin pathway, leptin antagonist triple mutant human recombinant (leptin tA) attenuated the cytoprotective effect of LXA4 ME against ketamine-induced neurotoxicity. In conclusion, our findings demonstrated LXA4 ME could exert a neuroprotective effect on ketamine-induced neuronal injury via activation of the leptin signaling pathway.

Lipoxins in the Nervous System: Brighter Prospects for Neuroprotection

Lipoxins (LXs) are generated from arachidonic acid and are involved in the resolution of inflammation and confer protection in a variety of pathological processes. In the nervous system, LXs exert an array of protective effects against neurological diseases, including ischemic or hemorrhagic stroke, neonatal hypoxia-ischemia encephalopathy, brain and spinal cord injury, Alzheimer's disease, multiple sclerosis, and neuropathic pain. Lipoxin administration is a potential therapeutic strategy in neurological diseases due to its notable efficiency and unique superiority regarding safety. Here, we provide an overview of LXs in terms of their synthesis, signaling pathways and neuroprotective evidence. Overall, we believe that, along with advances in lipoxin-related drug design, LXs will bring brighter prospects for neuroprotection.

5-Dodecanolide, a Compound Isolated from Pig Lard, Presents Powerful Anti-Inflammatory Properties

BACKGROUND

Pork lard (PL) is traditionally used as an anti-inflammatory agent. We propose to demonstrate the anti-inflammatory properties of PL, and elucidate which compounds could be responsible for the anti-inflammatory effects.

METHODS

The anti-inflammatory effects of PL were tested in a rat model of zymosan-induced hind paw inflammation. Further, the hydroalcoholic extract from PL was obtained, the composition analyzed, and the anti-inflammatory activity of the extracts and isolated components assayed using immune cells stimulated with lipopolysaccharide (LPS).

RESULTS

Applying the ointment on the inflamed rat feet reduced the foot diameter, foot weight, and activities of antioxidant enzymes and inflammatory markers of circulating neutrophils. The main components of the hydroalcoholic extract were 5-dodecanolide, oleamide, hexadecanoic acid, 9-octadecenoic acid, hexadecanamide, and resolvin D1.

CONCLUSIONS

PL reduces the immune response in an animal model stimulated with zymosan. Hydroalcoholic PL extract and its components (5-Dodecanolide, Oleamide, and Resolvin D1) exerted an anti-inflammatory effect on LPS-stimulated neutrophils and peripheral mononuclear cells reducing the capability to produce TNFα, as well as the activities of antioxidant and pro-inflammatory enzymes. These effects are attributable to 5-dodecanolide, although the effects of this compound alone do not reach the magnitude of the anti-inflammatory effects observed by the complete hydroalcoholic extract.

Lipid Oxidation Products on Inflammation-Mediated Hypertension and Atherosclerosis: A Mini Review

Cardiovascular diseases such as hypertension and atherosclerosis are the common causes of mortality in developed and developing countries. Repeated heating of the dietary oil is a common practice to reduce cost during food preparation. When the cooking oil is heated at high temperatures, production of free radicals augments the oxidative degradation of lipids and depletes the natural antioxidant contents of the cooking oil. Chronic intake of foods prepared using reheated oil could impair antioxidant capacity, leading to oxidative stress and inflammation. This review aims to summarize the current evidence of lipid oxidation products on hypertension and atherosclerosis via inflammatory pathway. In particular, toxic lipid oxidation products such as malondialdehyde and 4-hydroxy-2-nonenal are taken into account. Understanding the signaling pathways underlying the pathology associated with the lipid oxidation-derived aldehydes may be useful to develop therapeutic strategies for the prevention of inflammatory-related cardiovascular complications.

Oxidized phospholipids on alkyl-amide scaffold demonstrate anti-endotoxin and endothelial barrier-protective properties

Oxidized phospholipids (OxPLs) containing enzymatically or non-enzymatically oxidized fatty acids (oxylipins) are increasingly recognized as lipid mediators involved in pathogenesis of diseases. Further understanding of structure-activity relationship and molecular mechanisms activated by OxPLs is hampered by the complexity of synthesis of individual molecular species. Although dozens of individual free oxylipins are commercially available, their attachment to the phospholipid scaffold requires relatively harsh conditions during activation of carboxy-group, which may lead to decomposition of unstable oxylipins. Furthermore, additional protection-deprotection steps are required for oxylipins containing hydroxy-groups. In this work we describe synthesis of OxPLs containing oxylipins bound at the sn-2-position via an amide-bond that is characteristic of sphingophospholipids. Activation of oxylipins and attachment to the phospholipid scaffold are performed under mild conditions and characterized by high yield. Hydroxy-groups of oxylipins do not interfere with reactions and therefore no protection/deprotection steps are needed. In order to prevent oxylipin migration, a fatty acid residue at the sn-1 was bound through an alkyl bond, which is a common bond present in a large proportion of naturally occurring phospholipids. An additional advantage of combining alkyl and amide bonds in a single phospholipid molecule is that both types of bonds are phospholipase A₁/A₂-resistant, which may be expected to improve biological stability of OxPLs and thus simplify analysis of their effects. As proof of principle, several alkyl-amide oxidized phosphatidylcholines (OxPCs) containing either linear or prostane ring oxylipins have been synthesized. Importantly, we show here that alkyl-amide-OxPCs demonstrated biological activities similar to those of di-acyl-OxPCs. Alkyl-amide-OxPCs inhibited pro-inflammatory action of LPS and increased endothelial cellular barrier in vitro and in mouse models. The effects of alkyl-amide and di-acyl-OxPCs developed in a similar range of concentrations. We hypothesize that alkyl-amide-OxPLs may become a useful tool for deeper analysis of the structure-activity relationship of OxPLs.

Endothelial Immunity Trained by Coronavirus Infections, DAMP Stimulations and Regulated by Anti-Oxidant NRF2 May Contribute to Inflammations, Myelopoiesis, COVID-19 Cytokine Storms and Thromboembolism

To characterize transcriptomic changes in endothelial cells (ECs) infected by coronaviruses, and stimulated by DAMPs, the expressions of 1311 innate immune regulatomic genes (IGs) were examined in 28 EC microarray datasets with 7 monocyte datasets as controls. We made the following findings: The majority of IGs are upregulated in the first 12 hours post-infection (PI), and maintained until 48 hours PI in human microvascular EC infected by middle east respiratory syndrome-coronavirus (MERS-CoV) (an EC model for COVID-19). The expressions of IGs are modulated in 21 human EC transcriptomic datasets by various PAMPs/DAMPs, including LPS, LPC, shear stress, hyperlipidemia and oxLDL. Upregulation of many IGs such as nucleic acid sensors are shared between ECs infected by MERS-CoV and those stimulated by PAMPs and DAMPs. Human heart EC and mouse aortic EC express all four types of coronavirus receptors such as ANPEP, CEACAM1, ACE2, DPP4 and virus entry facilitator TMPRSS2 (heart EC); most of coronavirus replication-transcription protein complexes are expressed in HMEC, which contribute to viremia, thromboembolism, and cardiovascular comorbidities of COVID-19. ECs have novel trained immunity (TI), in which subsequent inflammation is enhanced. Upregulated proinflammatory cytokines such as TNFα, IL6, CSF1 and CSF3 and TI marker IL-32 as well as TI metabolic enzymes and epigenetic enzymes indicate TI function in HMEC infected by MERS-CoV, which may drive cytokine storms. Upregulated CSF1 and CSF3 demonstrate a novel function of ECs in promoting myelopoiesis. Mechanistically, the ER stress and ROS, together with decreased mitochondrial OXPHOS complexes, facilitate a proinflammatory response and TI. Additionally, an increase of the regulators of mitotic catastrophe cell death, apoptosis, ferroptosis, inflammasomes-driven pyroptosis in ECs infected with MERS-CoV and the upregulation of pro-thrombogenic factors increase thromboembolism potential. Finally, NRF2-suppressed ROS regulate innate immune responses, TI, thrombosis, EC inflammation and death. These transcriptomic results provide novel insights on the roles of ECs in coronavirus infections such as COVID-19, cardiovascular diseases (CVD), inflammation, transplantation, autoimmune disease and cancers.

From Vietnamese plants to a biflavonoid that relieves inflammation by triggering the lipid mediator class switch to resolution

Chronic inflammation results from excessive pro-inflammatory signaling and the failure to resolve the inflammatory reaction. Lipid mediators orchestrate both the initiation and resolution of inflammation. Switching from pro-inflammatory to pro-resolving lipid mediator biosynthesis is considered as efficient strategy to relieve chronic inflammation, though drug candidates exhibiting such features are unknown. Starting from a library of Vietnamese medical plant extracts, we identified isomers of the biflavanoid 8-methylsocotrin-4'-ol from Dracaena cambodiana, which limit inflammation by targeting 5-lipoxygenase and switching the lipid mediator profile from leukotrienes to specialized pro-resolving mediators (SPM). Elucidation of the absolute configurations of 8-methylsocotrin-4'-ol revealed the 2S,γS-isomer being most active, and molecular docking studies suggest that the compound binds to an allosteric site between the 5-lipoxygenase subdomains. We identified additional subordinate targets within lipid mediator biosynthesis, including microsomal prostaglandin E2 synthase-1. Leukotriene production is efficiently suppressed in activated human neutrophils, macrophages, and blood, while the induction of SPM biosynthesis is restricted to M2 macrophages. The shift from leukotrienes to SPM was also evident in mouse peritonitis in vivo and accompanied by a substantial decrease in immune cell infiltration. In summary, we disclose a promising drug candidate that combines potent 5-lipoxygenase inhibition with the favorable reprogramming of lipid mediator profiles.

Innate Immune Interference Attenuates Inflammation In Bacillus Endophthalmitis

Purpose

To explore the consequences of innate interference on intraocular inflammatory responses during Bacillus endophthalmitis.

Methods

Bacillus endophthalmitis was induced in mice. Innate immune pathway activation was interfered by injecting S layer protein-deficient (∆slpA) B. thuringiensis or by treating wild-type (WT)–infected mice with a TLR2/4 inhibitor (WT+OxPAPC). At 10 hours postinfection, eyes were harvested and RNA was purified. A NanoString murine inflammation panel was used to compare gene expression in WT-infected, WT+OxPAPC, ∆slpA-infected, and uninfected eyes.

Results

In WT-infected eyes, 56% of genes were significantly upregulated compared to uninfected controls. Compared to WT-infected eyes, the expression of 27% and 50% of genes were significantly reduced in WT+OxPAPC and ∆slpA-infected eyes, respectively. Expression of 61 genes that were upregulated in WT-infected eyes was decreased in WT+OxPAPC and ∆slpA-infected eyes. Innate interference resulted in blunted expression of complement factors (C3, Cfb, and C6) and several innate pathway genes (TLRs 2, 4, 6, and 8, MyD88, Nod2, Nlrp3, NF-κB, STAT3, RelA, RelB, and Ptgs2). Innate interference also reduced the expression of several inflammatory cytokines (CSF2, CSF3, IL-6, IL-1β, IL-1α, TNFα, IL-23α, TGFβ1, and IL-12β) and chemokines (CCL2, CCL3, and CXCLs 1, 2, 3, 5, 9, and 10). All of the aforementioned genes were significantly upregulated in WT-infected eyes.

Conclusions

These results suggest that interfering with innate activation significantly reduced the intraocular inflammatory response in Bacillus endophthalmitis. This positive clinical outcome could be a strategy for anti-inflammatory therapy of an infection typically refractory to corticosteroid treatment.

Resveratrol improves Gly-LDL-induced vascular endothelial cell apoptosis, inflammatory factor secretion and oxidative stress by regulating miR-142-3p and regulating SPRED2-mediated autophagy

BACKGROUND

Resveratrol improves cell apoptosis and tissue damage induced by high glucose, but the specific mechanism is unknown.

METHODS

This is a basic research. We performed cell transfection, real-time fluorescence quantitative PCR (qPCR), flow cytometry, immunofluorescence, western blot, enzyme linked immunosorbent assay (ELISA) and cell viability assay to analyze cell viability, cell cycle, cellular oxidative stress, intracellular inflammatory factors and autophagy activities in vitro. Meanwhile, dual luciferase reporter assay was conducted to explore the influence of miR-142-3p and sprouty-related EVH1 domain 2 (SPRED 2) on human glycated low-density lipoprotein (Gly-LDL)-induced vascular endothelial cell apoptosis, inflammatory factor secretion and oxidative stress.

RESULTS

Resveratrol inhibited the expression of miR-142-3p in human umbilical vein endothelial cells (HUVECs) induced by Gly-LDL in a dose-dependent manner, and the overexpression of miR-142-3p reverses the effect of resveratrol on the proliferation, apoptosis, secretion of inflammatory factors, oxidative stress, and autophagy. The dual-luciferase report analysis found a negative regulatory relationship between miR-142-3p and SPRED2. Inhibition of SPRED2 reversed the effects of resveratrol on Gly-LDL-induced HUVECs proliferation, apoptosis, inflammatory factor secretion and oxidative stress, and reversed the effects of resveratrol on Gly-LDL-induced HUVECs autophagy.

CONCLUSION

miR-142-3p promotes the development of diabetes by inhibiting SPRED2-mediated autophagy, including inducing cell apoptosis, aggravating cellular oxidative stress and secretion of inflammatory factors, and resveratrol improves this effect.

Allergen inhalation generates pro-inflammatory oxidised phosphatidylcholine associated with airway dysfunction

Oxidised phosphatidylcholines (OxPCs) are produced under conditions of elevated oxidative stress and can contribute to human disease pathobiology. However, their role in allergic asthma is unexplored. The aim of this study was to characterise the OxPC profile in the airways after allergen challenge of people with airway hyperresponsiveness (AHR) or mild asthma. The capacity of OxPCs to contribute to pathobiology associated with asthma was also to be determined.Using bronchoalveolar lavage fluid from two human cohorts, OxPC species were quantified using ultra-high performance liquid chromatography-tandem mass spectrometry. Murine thin-cut lung slices were used to measure airway narrowing caused by OxPCs. Human airway smooth muscle (HASM) cells were exposed to OxPCs to assess concentration-associated changes in inflammatory phenotype and activation of signalling networks.OxPC profiles in the airways were different between people with and without AHR and correlated with methacholine responsiveness. Exposing patients with mild asthma to allergens produced unique OxPC signatures that associated with the severity of the late asthma response. OxPCs dose-dependently induced 15% airway narrowing in murine thin-cut lung slices. In HASM cells, OxPCs dose-dependently increased the biosynthesis of cyclooxygenase-2, interleukin (IL)-6, IL-8, granulocyte-macrophage colony-stimulating factor and the production of oxylipins via protein kinase C-dependent pathways.Data from human cohorts and primary HASM cell culture show that OxPCs are present in the airways, increase after allergen challenge and correlate with metrics of airway dysfunction. Furthermore, OxPCs may contribute to asthma pathobiology by promoting airway narrowing and inducing a pro-inflammatory phenotype and contraction of airway smooth muscle. OxPCs represent a potential novel target for treating oxidative stress-associated pathobiology in asthma.

The Potential for Phospholipids in the Treatment of Airway Inflammation: An Unexplored Solution

Asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF) are major inflammatory respiratory diseases. Current mainstay therapy for asthma, and chronic obstructive pulmonary disease are corticosteroids, which have well-established side effect profiles. Phospholipids (PLs) are ubiquitous, diverse compounds with varying functions such as their structural role incell membrane, energy storage, and cell signaling.Recent advances in understanding PLs role as inflammatory mediators in the body as well as their widespread long-standing use as carrier molecules in drug delivery demonstrate the potential application of phospholipids in modulating inflammatory conditions. This review briefly explains the main mechanisms of inflammation in chronic respiratory diseases, currentanti-inflammatory treatments and areas of unmet need. The structural features, roles of endogenous and exogenous phospholipids, including their use as pharmaceutical excipients are reviewed. Current research on the immunomodulatory properties of PLs and their potentialapplication in inflammatory diseasesis the major section of this review. Considering the roles of PLs as inflammatory mediators and their safety profile established in pharmaceutical formulations, these small molecules demonstrate great potential as candidates in respiratory inflammation. Future studies need to focus on the immunomodulatory properties and the underlying mechanisms of phospholipids in respiratory inflammatory diseases.

Oxidized Phospholipids in Control of Endothelial Barrier Function: Mechanisms and Implication in Lung Injury

Earlier studies investigating the pathogenesis of chronic vascular inflammation associated with atherosclerosis described pro-inflammatory and vascular barrier disruptive effects of lipid oxidation products accumulated in the sites of vascular lesion and atherosclerotic plaque. However, accumulating evidence including studies from our group suggests potent barrier protective and anti-inflammatory properties of certain oxidized phospholipids (OxPLs) in the lung vascular endothelium. Among these OxPLs, oxidized 1-palmitoyl-2-arachdonyl-sn-glycero-3-phosphocholine (OxPAPC) causes sustained enhancement of lung endothelial cell (EC) basal barrier properties and protects against vascular permeability induced by a wide variety of agonists ranging from bacterial pathogens and their cell wall components, endotoxins, thrombin, mechanical insults, and inflammatory cytokines. On the other hand, truncated OxPLs cause acute endothelial barrier disruption and potentiate inflammation. It appears that multiple signaling mechanisms triggering cytoskeletal remodeling are involved in OxPLs-mediated regulation of EC barrier. The promising vascular barrier protective and anti-inflammatory properties exhibited by OxPAPC and its particular components that have been established in the cellular and animal models of sepsis and acute lung injury has prompted consideration of OxPAPC as a prototype therapeutic molecule. In this review, we will summarize signaling and cytoskeletal mechanisms involved in OxPLs-mediated damage, rescue, and restoration of endothelial barrier in various pathophysiological settings and discuss a future potential of OxPAPC in treating lung disorders associated with endothelial barrier dysfunction.

Ursodeoxycholic acid protects against lung injury induced by fat embolism syndrome

Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is a life‐threatening disease with a high mortality rate, which was a common complication of fat embolism syndrome (FES). Ursodeoxycholic acid (UDCA) has been reported to exert potent anti‐inflammatory effects under various conditions. In vivo, perinephric fat was injected via tail vein to establish a rat FES model, the anti‐inflammatory effects of UDCA on FES‐induced lung injury were investigated through histological examination, ELISA, qRT‐PCR, Western blot and immunofluorescence. In vitro, human lung microvascular endothelial cells (HPMECs) were employed to understand the protective effects of UDCA. The extent of ALI/ARDS was evaluated and validated by reduced PaO₂/FiO₂ ratios, increased lung wet/dry (W/D) ratios and impaired alveolar‐capillary barrier, up‐regulation of ALI‐related proteins in lung tissues (including myeloperoxidase [MPO], vascular cell adhesion molecule 1 [VCAM‐1], intercellular cell adhesion molecule‐1 [ICAM‐1]), elevated protein concentration and increased proinflammatory cytokines levels (TNF‐α and IL‐1β) in bronchoalveolar lavage fluid (BALF). Pre‐treatment with UDCA remarkably alleviated these pathologic and biochemical changes of FES‐induced ALI/ARDS; our data demonstrated that pre‐treatment with UDCA attenuated the pathologic and biochemical changes of FES‐induced ARDS, which provided a possible preventive therapy for lung injury caused by FES.

Insights into the prognosis of lipidomic dysregulation for death risk in patients with coronary artery disease

BACKGROUND

Dyslipidaemia contributes to the progression of coronary artery disease (CAD) toward adverse outcomes. Plasma lipidomic measure may improve the prognostic performances of clinical endpoints of CAD. Our research is designed to identify the correlations between plasma lipid species and the risks of death, major adverse cardiovascular event (MACE) and left ventricular (LV) remodeling in patients with CAD.

METHODS

A total of 1569 Chinese patients with CAD, 1011 single-centre patients as internal training cohort, and 558 multicentre patients as external validation cohort, were enrolled. The concentration of plasma lipids in both cohorts was determined through widely targeted lipidomic profiling. Least absolute shrinkage and selection operator Cox and multivariate Cox regressions were used to develop prognostic models for death and MACE, respectively.

RESULTS

Ten (Cer(d18:1/20:1), Cer(d18:1/24:1), PE(30:2), PE(32:0), PE(32:2), PC(O-38:2), PC(O-36:4), PC(16:1/22:2), LPC(18:2/0:0) and LPE(0:0/24:6)) and two (Cer(d18:1/20:1) and LPC(20:0/0:0)) lipid species were independently related to death and MACE, respectively. Cer(d18:1/20:1) and Cer(d18:1/24:1) were correlated with LV remodeling (P < .05). The lipidic panel incorporating 10 lipid species and two traditional biomarkers for predicting 5-year death risk represented a remarkable higher discrimination than traditional model with increased area under the curve from 76.56 to 83.65%, continuous NRI of 0.634 and IDI of 0.131. Furthermore, the panel was successfully used in differentiating multicentre patients with low, middle, or high risks (P < .0001). Further analysis indicated that the number of double bonds of phosphatidyl choline and the content of carbon atoms of phosphatidyl ethanolamines were negatively associated with death risk.

CONCLUSIONS

Improvement in the prediction of death confirms the effectiveness of plasma lipids as predictors to risk classification in patients with CAD. The association between the structural characteristics of long-chain polyunsaturated fatty acids and death risk highlights the need for mechanistic research that characterizes the role of individual lipid species in disease pathogenesis.

Oxidized Phospholipids in Healthy and Diseased Lung Endothelium

Circulating and cell membrane phospholipids undergo oxidation caused by enzymatic and non-enzymatic mechanisms. As a result, a diverse group of bioactive oxidized phospholipids generated in these conditions have both beneficial and harmful effects on the human body. Increased production of oxidized phospholipid products with deleterious effects is linked to the pathogenesis of various cardiopulmonary disorders such as atherosclerosis, thrombosis, acute lung injury (ALI), and inflammation. It has been determined that the contrasting biological effects of lipid oxidation products are governed by their structural variations. For example, full-length products of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine oxidation (OxPAPC) have prominent endothelial barrier protective and anti-inflammatory activities while most of the truncated oxidized phospholipids induce vascular leak and exacerbate inflammation. The extensive studies from our group and other groups have demonstrated a strong potential of OxPAPC in mitigating a wide range of agonist-induced lung injuries and inflammation in pulmonary endothelial cell culture and rodent models of ALI. Concurrently, elevated levels of truncated oxidized phospholipids are present in aged mice lungs that potentiate the inflammatory agents-induced lung injury. On the other hand, increased levels of full length OxPAPC products accelerate ALI recovery by facilitating production of anti-inflammatory lipid mediator, lipoxin A4, and other molecules with anti-inflammatory properties. These findings suggest that OxPAPC-assisted lipid program switch may be a promising therapeutic strategy for treatment of acute inflammatory syndromes. In this review, we will summarize the vascular-protective and deleterious aspects of oxidized phospholipids and discuss their therapeutic potential including engineering of stable analogs of oxidized phospholipids with improved anti-inflammatory and barrier-protective properties.

Lipoxin A4 reduces house dust mite and TNFα-induced hyperreactivity in the mouse trachea

Lipoxin A₄ (LXA₄) is considered a specialised pro-resolving mediator that decreases inflammation: however, pro-inflammatory effects have been described in the airways. Here, we investigated whether LXA₄ could influence airway hyperreactivity induced in mouse trachea by house dust mite extract (HDM) or TNFα. Intranasal instillation of HDM caused a serotonin (5-HT) mediated airway hyperreactivity ex vivo (E_max: 78.1 ± 16.2 % versus control 12.8 ± 1.0 %) that was reduced by LXA₄ installation one hour prior to HDM (E_max: 49.9 ± 11.4 %). Also, in isolated tracheal segments cultured for four days, HDM induced a hyperreactivity (E_max: 33.2 ± 3.1 % versus control 9.0 ± 0.7 %) that was decreased by LXA₄ (E_max: 18.7 ± 1.5 %). One part of the HDM-induced hyperreactivity could be inhibited by the TNFα-inhibitor etanercept. TNFα-induced upregulation of 5-HT responses (E_max: 51.3 ± 1.2 % versus control 13.9 ± 0.5 %) was decreased by 10-1000 nM LXA₄. In precontracted tracheal segments, LXA₄ had no relaxing effect. Overall, LXA₄ was able to decrease airway hyperreactivity induced by both HDM and TNFα, thus having a sub-acute anti-inflammatory effect in airway inflammation.

Inflammation resolution and specialized pro-resolving lipid mediators in CNS diseases

Introduction: Inflammation resolution induced by specialized pro-resolving lipid mediators (SPMs) is a new concept. The application of SPMs is a promising therapeutic strategy that can potentially supersede anti-inflammatory drugs. Most CNS diseases are associated with hyperreactive inflammatory damage. CNS inflammation causes irreversible neuronal loss and permanent functional impairments. Given the high mortality and morbidity rates, the investigation of therapeutic strategies to ameliorate inflammatory damage is necessary.Areas covered: In this review, we explore inflammation resolution in CNS disorders. We discuss the underlying mechanisms and dynamic changes of SPMs and their precursors in neurological diseases and examine how this can potentially be incorporated into the clinic. References were selected from PubMed; most were published between 2010 and 2019.Expert opinion: Inflammation resolution is a natural process that emerges after acute or chronic inflammation. The evidence that SPMs can effectively ameliorate hyperreactive inflammation, shorten resolution time and accelerate tissue regeneration in CNS disorders. Adjuvants and nanotechnology offer opportunities for SPM drug design; however, more preclinical studies are necessary to investigate basic, critical issues such as safety.

Evaluation of air oxidized PAPC: A multi laboratory study by LC-MS/MS

Oxidized LDL (oxLDL) has been shown to play a crucial role in the onset and development of cardiovascular disorders. The study of oxLDL, as an initiator of inflammatory cascades, led to the discovery of a variety of oxidized phospholipids (oxPLs) responsible for pro-inflammatory actions. Oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC) is frequently used by the scientific community as a representative oxPL mixture to study the biological effects of oxidized lipids, due to the high abundance of PAPC in human tissues and the biological activities of oxidized arachidonic acids derivatives. Most studies focusing on oxPAPC effects rely on in-house prepared mixtures of oxidized species obtained by exposing PAPC to air oxidation. Here, we described a multi-laboratory evaluation of the compounds in oxPAPC by LC-MS/MS, focusing on the identification and relative quantification of the lipid peroxidation products (LPPs) formed. PAPC was air-oxidized in four laboratories using the same protocol for 0, 48, and 72 h. It was possible to identify 55 different LPPs with unique elemental composition and characterize different structural isomeric species within these. The study showed good intra-sample reproducibility and similar qualitative patterns of oxidation, as the most abundant LPPs were essentially the same between the four laboratories. However, there were substantial differences in the extent of oxidation, i.e. the amount of LPPs relative to unmodified PAPC, at specific time points. This shows the importance of characterizing air-oxidized PAPC preparations before using them for testing biological effects of oxidized lipids, and may explain some variability of effects reported in the literature.

RhoGTPase in Vascular Disease

Ras-homologous (Rho)A/Rho-kinase pathway plays an essential role in many cellular functions, including contraction, motility, proliferation, and apoptosis, inflammation, and its excessive activity induces oxidative stress and promotes the development of cardiovascular diseases. Given its role in many physiological and pathological functions, targeting can result in adverse effects and limit its use for therapy. In this review, we have summarized the role of RhoGTPases with an emphasis on RhoA in vascular disease and its impact on endothelial, smooth muscle, and heart and lung fibroblasts. It is clear from the various studies that understanding the regulation of RhoGTPases and their regulators in physiology and pathological conditions is required for effective targeting of Rho.

Detrimental Role of miRNA-144-3p in Intracerebral Hemorrhage Induced Secondary Brain Injury is Mediated by Formyl Peptide Receptor 2 Downregulation Both In Vivo and In Vitro

Although microRNA-144-3p (miRNA-144-3p) has been shown to suppress tumor proliferation and invasion, its function in intracerebral hemorrhage (ICH)-induced secondary brain injury (SBI) remains unclear. Thus, this study was designed to investigate the role of miRNA-144-3p in ICH. To accomplish this, we used adult male Sprague-Dawley rats to establish an in vivo ICH model by injecting autologous blood, while cultured primary rat cortical neurons were exposed to oxyhemoglobin (OxyHb) to mimic ICH in vitro. To examine the role of miRNA-144-3p in ICH-induced SBI, we used an miRNA-144-3p mimic and inhibitor both in vivo and in vitro. Following ICH induction, we found miRNA-144-3p expression to increase. Additionally, we predicted the formyl peptide receptor 2 (FPR2) to be a potential miRNA-144-3p target, which we validated experimentally, with FPR2 expression downregulated when miRNA-144-3p was upregulated. Furthermore, elevated miRNA-144-3p levels aggravated brain edema and neurobehavioral disorders and induced neuronal apoptosis via the downregulation of FPR2 both in vivo and in vitro. We suspected that these beneficial effects provided by FPR2 were associated with the PI3K/AKT pathway. We validated this finding by overexpressing FPR2 while inhibiting PI3K/AKT in vitro and in vivo. In conclusion, miRNA-144-3p aggravated ICH-induced SBI by targeting and downregulating FPR2, thereby contributing to neurological dysfunction and neural apoptosis via PI3K/AKT pathway activation. These findings suggest that inhibiting miRNA-144-3p may offer an effective approach to attenuating brain damage incurred after ICH and a potential therapy to improve ICH-induced SBI.

Role of truncated oxidized phospholipids in acute endothelial barrier dysfunction caused by particulate matter

Particulate matter (PM) air pollution is a global environmental health problem contributing to more severe lung inflammation and injury. However, the molecular and cellular mechanisms of PM-induced exacerbation of lung barrier dysfunction and injury are not well understood. In the current study, we tested a hypothesis that PM exacerbates vascular barrier dysfunction via ROS-induced generation of truncated oxidized phospholipids (Tr-OxPLs). Treatment of human pulmonary endothelial cells with PM caused endothelial cell barrier disruption in a dose-dependent fashion. Biochemical analysis showed destabilization of cell junctions by PM via tyrosine phosphorylation and internalization of VE-cadherin. These events were accompanied by PM-induced generation of Tr-OxPLs, detected by mass spectrometry analysis. Furthermore, purified Tr-OxPLs: POVPC, PGPC and lyso-PC alone, caused a rapid increase in endothelial permeability and augmented pulmonary endothelial barrier dysfunction induced by submaximal doses of PM. In support of a role of TR-OxPLs-dependent mechanism in mediation of PM effects, ectopic expression of intracellular type 2 platelet-activating factor acetylhydrolase (PAFAH2), which specifically hydrolyzes Tr-OxPLs, significantly attenuated PM-induced endothelial hyperpermeability. In summary, this study uncovered a novel mechanism of PM-induced sustained dysfunction of pulmonary endothelial cell barrier which is driven by PM-induced generation of truncated products of phospholipid oxidation causing destabilization of cell junctions.

NRF2 regulates endothelial glycolysis and proliferation with miR-93 and mediates the effects of oxidized phospholipids on endothelial activation

Phospholipids, such as 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (PAPC), are the major components of cell membranes. Their exposure to reactive oxygen species creates oxidized phospholipids, which predispose to the development of chronic inflammatory diseases and metabolic disorders through endothelial activation and dysfunction. Although the effects of oxidized PAPC (oxPAPC) on endothelial cells have been previously studied, the underlying molecular mechanisms evoking biological responses remain largely unknown. Here, we investigated the molecular mechanisms of oxPAPC function with a special emphasis on NRF2-regulated microRNAs (miRNAs) in human umbilical vein endothelial cells (HUVECs) utilizing miRNA profiling, global run-on sequencing (GRO-seq), genome-wide NRF2 binding model, and RNA sequencing (RNA-seq) with miRNA overexpression and silencing. We report that the central regulators of endothelial activity, KLF2 for quiescence, PFKFB3 for glycolysis, and VEGFA, FOXO1 and MYC for growth and proliferation, are regulated by transcription factor NRF2 and the NRF2-regulated miR-106b∼25 cluster member, miR-93, in HUVECs. Mechanistically, oxPAPC was found to induce glycolysis and proliferation NRF2-dependently, and oxPAPC-dependent induction of the miR-106b∼25 cluster was mediated by NRF2. Additionally, several regulatory loops were established between NRF2, miR-93 and the essential regulators of healthy endothelium, collectively implying that NRF2 controls the switch between the quiescent and the proliferative endothelial states together with miR-93.

Injured lung endothelium: mechanisms of self-repair and agonist-assisted recovery (2017 Grover Conference Series)

The lung endothelium is vulnerable to both exogenous and endogenous insults, so a properly coordinated efficient repair system is essential for the timely recovery of the lung after injury. The agents that cause endothelial injury and dysfunction fall into a broad range from mechanical forces such as pathological cyclic stretch and shear stress to bacterial pathogens and their virulent components, vasoactive agonists including thrombin and histamine, metabolic causes including high glucose and oxidized low-density lipoprotein (OxLDL), circulating microparticles, and inflammatory cytokines. The repair mechanisms employed by endothelial cells (EC) can be broadly categorized into three groups: (1) intrinsic mechanism of recovery regulated by the cross-talk between small GTPases as exemplified by Rap1-mediated EC barrier recovery from Rho-mediated thrombin-induced EC hyperpermeability; (2) agonist-assisted recovery facilitated by the activation of Rac and Rap1 with subsequent inhibition of Rho signaling as observed with many barrier protective agonists including oxidized phospholipids, sphingosine 1-phosphate, prostacyclins, and hepatocyte growth factor; and (3) self-recovery of EC by the secretion of growth factors and other pro-survival bioactive compounds including anti-inflammatory molecules such as lipoxins during the resolution of inflammation. In this review, we will discuss the molecular and cellular mechanisms of pulmonary endothelium repair that is critical for the recovery from various forms of lung injuries.

Lipid mediators in the regulation of endothelial barriers

Lipid mediators play a critical role in the development and resolution of vascular endothelial barrier dysfunction caused by various pathologic interventions. The accumulation of excess lipids directly impairs endothelial cell (EC) barrier function that is known to contribute to the development of atherosclerosis and metabolic disorders such as obesity and diabetes as well as chronic inflammation in the vascular endothelium. Certain products of phospholipid oxidation (OxPL) such as fragmented phospholipids generated during oxidative and nitrosative stress show pro-inflammatory potential and cause endothelial barrier dysfunction. In turn, other OxPL products enhance basal EC barrier and exhibit potent barrier-protective effects in pathologic settings of acute vascular leak caused by pro-inflammatory mediators, barrier disruptive agonists and pathologic mechanical stimulation. These beneficial effects were further confirmed in rodent models of lung injury and inflammation. The bioactive oxidized lipid molecules may serve as important therapeutic prototype molecules for future treatment of acute lung injury syndromes associated with endothelial barrier dysfunction and inflammation. This review will summarize recent studies of biological effects exhibited by various groups of lipid mediators with a focus on the role of oxidized phospholipids in control of vascular endothelial barrier, agonist induced EC permeability, inflammation, and barrier recovery related to clinical settings of acute lung injury and inflammatory vascular leak.