Apoptosis Of Human Neutrophils Research Articles

Caffeic acid modulates activation of neutrophils and attenuates sepsis-induced organ injury by inhibiting 5-LOX/LTB4 pathway

BackgroundSepsis is a critical systemic inflammatory syndrome which usually leads to multiple organ dysfunction. Caffeic acid (CA), a phenolic compound derived from various plants, has been proved to be essential in neuroprotection, but its role in septic organ damage is unclear. This research aimed to investigate whether CA protects against organ injury in a mouse model of cecal ligation and puncture (CLP). MethodsCA (30 mg/kg) or vehicle was administered by intraperitoneal injection immediately after CLP. The samples of blood, lungs, and livers were collected 24 h later. Organ injury was assessed by histopathological examination (HE staining), neutrophil infiltration (myeloperoxidase fluorescence), oxidative stress levels (MDA, SOD, HO-1), and inflammatory cytokines (TNF-α, IL-1β, and IL-6) release in lung and liver tissues. Neutrophil extracellular trap (NET) formation was analyzed by immunofluorescence. In vitro experiments were performed to investigate the potential mechanisms of CA using small interfering RNA (siRNA) techniques in neutrophils, and the effect of CA on neutrophil apoptosis was analyzed by flow cytometry. ResultsResults showed that CA treatment improved the 7-day survival rate and attenuated the histopathological injury in the lung and liver of CLP mice. CA significantly reduced neutrophil infiltration in the lungs and livers of CLP mice. TNF-α, IL-1β, IL-6 and LTB4 were reduced in serum, lung, and liver of CA-treated CLP mice, and phosphorylation of MAPK (p38, ERK, JNK) and p65 NF-κB was inhibited in lungs and livers. CA treatment further increased HO-1 levels and enhanced superoxide dismutase (SOD) activity, but reduced malondialdehyde (MDA) levels and NET formation. Similarly, in vitro experiments showed that CA treatment and 5-LOX siRNA interference inhibited inflammatory activation and NET release in neutrophils, suppressed MAPK and NF-κB phosphorylation in LPS-treated neutrophils, and decreased LTB4 and cfDNA levels. Flow cytometric analysis revealed that CA treatment reversed LPS-mediated delayed apoptosis in human neutrophils, and Western blot also indicated that CA treatment inhibited Bcl-2 expression but increased Bax expression. CA treatment did not induce further changes in neutrophil apoptosis, inflammatory activation, and NET release when 5-LOX was knocked down by siRNA interference. ConclusionsCA has a protective effect on lung and liver injury in a murine model of sepsis, which may be related to inhibition of the 5-LOX/LTB4 pathway.

The effect of local anaesthetics on apoptosis and NETosis of human neutrophils in vitro: comparison between lidocaine and ropivacaine

There are immunological consequences to the method by which neutrophils undergo cell death. Neutrophil apoptosis, called silent death, leads to the resolution of inflammation, while NETosis deepens and prolongs the inflammatory response and is associated with a worse prognosis of severe infections, e.g., sepsis. Besides nociceptive inhibition, local anaesthetics modulate leukocyte functions, even at low, clinically relevant concentrations. There is currently no data on ropivacaine NETosis, and this study aimed to evaluate the impact of clinical concentrations of ropivacaine (0.0007, 0.007 and 1.4 mmol/L) and lidocaine (0.002, 0.02 and 4 mmol/L) on apoptosis and NETosis of adult peripheral blood neutrophils after 2 h of incubation. Neutrophil identification, apoptosis and NETosis were evaluated by flow cytometry using forward and side scatter characteristics and fluorescent labelling: CD15 for neutrophils identification; Annexin V and propidium iodide for apoptosis and citrullinated histone H3 and myeloperoxidase for NETosis. Lidocaine (4 mmol/L) and ropivacaine (1.4 mmol/L) induced early apoptosis in resting but not in stimulated neutrophils. Low doses of ropivacaine (0.0007 and 0.007 mmol/L) decreased the number of late apoptotic neutrophils, and the lowest dose slightly increased their viability. None of the drugs induced NETosis in resting neutrophils but decreased NETosis at clinical concentrations compared to PMA-stimulated 4 mM lidocaine, PMA-stimulated control, and 1.4 mM ropivacaine. The effect of lidocaine and ropivacaine on apoptosis and NETosis depended on neutrophil stimulation and drug concentrations. Ropivacaine tends to be cytoprotective at concentrations observed in plasma under local anaesthesia. Lidocaine enhanced NETosis at high concentration only in stimulated neutrophils. Thus, both drugs have the ability to change the course of inflammation.

A novel phosphocholine-mimetic inhibits a pro-inflammatory conformational change in C-reactive protein.

C-reactive protein (CRP) is an early-stage acute phase protein and highly upregulated in response to inflammatory reactions. We recently identified a novel mechanism that leads to a conformational change from the native, functionally relatively inert, pentameric CRP (pCRP) structure to a pentameric CRP intermediate (pCRP*) and ultimately to the monomeric CRP (mCRP) form, both exhibiting highly pro-inflammatory effects. This transition in the inflammatory profile of CRP is mediated by binding of pCRP to activated/damaged cell membranes via exposed phosphocholine lipid head groups. We designed a tool compound as a low molecular weight CRP inhibitor using the structure of phosphocholine as a template. X-ray crystallography revealed specific binding to the phosphocholine binding pockets of pCRP. We provide invitro and invivo proof-of-concept data demonstrating that the low molecular weight tool compound inhibits CRP-driven exacerbation of local inflammatory responses, while potentially preserving pathogen-defense functions of CRP. The inhibition of the conformational change generating pro-inflammatory CRP isoforms via phosphocholine-mimicking compounds represents a promising, potentially broadly applicable anti-inflammatory therapy.

Wogonin attenuates neutrophilic inflammation and airway smooth muscle proliferation through inducing caspase-dependent apoptosis and inhibiting MAPK/Akt signaling in allergic airways.

Severe neutrophilic asthma is often characterized by persistent airway inflammation and irreversible airway remodeling, which are overstimulated by the high-mobility group box protein 1 (HMGB1). Although wogonin, an O-methylated flavone, has been widely used to treat inflammatory and allergic diseases, its therapeutic effects and potential mechanisms on severe neutrophilic asthma remain elusive. To evaluate whether wogonin alleviates airway neutrophilia through inducing neutrophil apoptosis and attenuates airway smooth muscle cells (ASMCs) proliferation and migration. The effect of wogonin on reducing neutrophilic airway inflammation, including neutrophil infiltration and inflammatory mediators, was examined in a mouse model of severe neutrophilic asthma sensitized with ovalbumin and lipopolysaccharide. Also, the effect of wogonin on inducing human neutrophil apoptosis was manifested using cellular morphology, flow cytometry, and caspase inhibition assays. Furthermore, the effect of wogonin on inhibiting HMGB1-mediated ASMCs proliferation and migration was determined. Wogonin reduced the frequency of neutrophils and inhibited the production of multiple inflammatory mediators, including ovalbumin-specific IgE, tumor necrosis factor-α, interleukin-6, and HMGB1, in bronchoalveolar lavage fluid and lung tissues of the neutrophilic asthmatic mouse model. These data strongly support a significantly suppressed neutrophilic airway inflammation, functionally consistent to the relieved airway hyperresponsiveness by wogonin in vivo. Wogonin induced human neutrophil apoptosis in a dose-dependent manner by activating caspase-8 and caspase-3 in vitro. Wogonin pretreatment abolished HMGB1-induced ASMCs proliferation and migration, which can be explained by the inhibition of phosphorylation in the mitogen-activated protein kinase (MAPK) /Akt singling pathways. Our findings demonstrate that wogonin augments caspase-dependent apoptosis in neutrophils to alleviate neutrophilic inflammatory responses and regulates intracellular signaling to inhibit HMGB1-mediated ASMCs activation, providing a promising therapeutic agent for severe neutrophilic asthma.

Chlamydia psittaci inhibits apoptosis of human neutrophils by activating P2X7 receptor expression

This study tested the hypothesis that Chlamydia psittaci (C. psittaci) survives and multiplies in human neutrophils by activating P2X7, a nonselective cationic channel receptor expressed constitutively on the surface of these cells. Findings illustrated that P2X7 receptor expression was enhanced in C. psittaci-infected neutrophils. C. psittaci was able to inhibite spontaneous apoptosis of neutrophils through mitochondrial-induced ATP release and IL-8 production. Importantly, inhibiting ATP activation of the P2X7 receptor with AZ10606120 promotes apoptosis, while stimulating P2X7 receptor expression with BzATP delayed spontaneous apoptosis of human neutrophils, suggesting that C. psittaci inhibits apoptosis of human neutrophils by activating P2X7 receptor. This study reveals new insights into the survival advantages of the latent persistent state of C. psittaci and the mechanism by which it evades the innate immune response.

Interferon-β regulates proresolving lipids to promote the resolution of acute airway inflammation.

Aberrant immune responses, including hyperresponsiveness to Toll-like receptor (TLR) ligands, underlie acute respiratory distress syndrome (ARDS). Type I interferons confer antiviral activities and could also regulate the inflammatory response, whereas little is known about their actions to resolve aberrant inflammation. Here we report that interferon-β (IFN-β) exerts partially overlapping, but also cooperative actions with aspirin-triggered 15-epi-lipoxin A4 (15-epi-LXA4) and 17-epi-resolvin D1 to counter TLR9-generated cues to regulate neutrophil apoptosis and phagocytosis in human neutrophils. In mice, TLR9 activation impairs bacterial clearance, prolongs Escherichia coli-evoked lung injury, and suppresses production of IFN-β and the proresolving lipid mediators 15-epi-LXA4 and resolvin D1 (RvD1) in the lung. Neutralization of endogenous IFN-β delays pulmonary clearance of E. coli and aggravates mucosal injury. Conversely, treatment of mice with IFN-β accelerates clearance of bacteria, restores neutrophil phagocytosis, promotes neutrophil apoptosis and efferocytosis, and accelerates resolution of airway inflammation with concomitant increases in 15-epi-LXA4 and RvD1 production in the lungs. Pharmacological blockade of the lipoxin receptor ALX/FPR2 partially prevents IFN-β-mediated resolution. These findings point to a pivotal role of IFN-β in orchestrating timely resolution of neutrophil and TLR9 activation-driven airway inflammation and uncover an IFN-β-initiated resolution program, activation of an ALX/FPR2-centered, proresolving lipids-mediated circuit, for ARDS.

Treponema pallidum delays the apoptosis of human polymorphonuclear neutrophils through the intrinsic and extrinsic pathways

Treponema pallidum is a “stealth pathogen” responsible for infectious sexually transmitted diseases. Although neutrophils are usually present in skin lesions of early syphilis, the role of these cells in T. pallidum infection has barely been investigated. Neutrophils are short-lived cells that undergo constitutive apoptosis, and phagocytosis usually accelerates this process. Here, we demonstrated that human polymorphonuclear neutrophils (hPMNs) could phagocytose T. pallidum in vitro. An unexpected discovery was that T. pallidum inhibited hPMNs apoptosis markedly in an opsonin-independent manner. Furthermore, this phenomenon was not affected by bacterial viability, as detected by annexin V, morphology studies, and TUNEL staining. Exploration of the underlying mechanism showed that expression of the cleaved forms of caspase-3, −8, and −9 and effector caspase activity were diminished significantly in T. pallidum-infected hPMNs. T. pallidum also impaired staurosporine- and anti-Fas-induced signaling for neutrophil apoptosis. Of note, these effects were accompanied by inducing the autocrine production of the anti-apoptotic cytokine IL-8. Taken together, our data revealed that T. pallidum could inhibit the apoptosis of hPMNs through intrinsic and extrinsic pathways and provide new insights for understanding the pathogenicity mechanisms of T. pallidum.

Effect of Xenon on Proinflammatory Activation and Apoptosis of Human Neutrophils Under Ex Vivo Conditions

Background. The syndrome of systemic inflammatory response, which underlies the damaging effect of factors of infectious and non-infectious genesis, may cause multiple organ failure. The degree of its severity is determined, among other things, by the activation of neutrophils. The paper highlights new mechanisms of the anti-inflammatory action of the inhalation anesthetic xenon, mediated by a decrease in the ability of neutrophils to pro-inflammatory response.Aim of study. To evaluate the effect of xenon on the activation of human neutrophils under ex vivo conditions.Material AND methods. We studied the effect of xenon inhalation on reduction of the ability of neutrophils to be activated proinflammatory by reduced expression of adhesion molecules CD11b and CD66b on the surface of neutrophils and on the phosphorylation of proinflammatory kinases: ERK 1/2 and kinase — p38 in neutrophils of healthy volunteers.Results. The use of xenon at a dose of 30 vol. % within 60 minutes in healthy volunteers statistically significantly reduces the ability of neutrophils to proinflammatory activation. The addition of lipopolysaccharide (LPS) to the incubation medium of neutrophils causes their pronounced activation, statistically significantly increasing the phosphorylation of key proinflammatory neutrophil kinases ERK1/2 and kinase p38. Inhalation of xenon in volunteers (30% within 60 minutes) has a pronounced anti-inflammatory effect on LPS-stimulated neutrophils, decreasing their activation by inhibiting pro-inflammatory kinase ERK1/2 and pro-inflammatory MAP kinase p38.Conclusion. The actual study, performed on isolated neutrophils from volunteers who underwent xenon inhalation, revealed the anti-inflammatory properties of the inert gas xenon, which, in our opinion, may have a direct relationship to the identification of the mechanism of its neuroprotective properties. Thus, the research results available today suggest that xenon has a pronounced pleiotropic mechanism of brain protection. This is a partial blockade of NMDA receptors, and phosphorylation of the enzyme glycogen synthase-3β, and limitation of the inflammatory activation of neutrophils.Findings. Inhalation of xenon in volunteers (30% within 60 minutes) has a pronounced anti-inflammatory effect on neutrophils stimulated by lipopolysaccharides, decreasing their activation by inhibiting proinflammatory ERK 1/2 kinase and proinflammatory MAP kinase p38, as well as reducing the expression of markers of activation and degranulation CD11b and CD66b on the surface of neutrophils. Stimulation by lipopolysaccharides statistically significantly reduces spontaneous apoptosis of neutrophils, while xenon increases the ability of neutrophils to apoptosis, which is likely to contribute to the resolution of inflammation.

BCL-XL antagonism selectively reduces neutrophil life span within inflamed tissues without causing neutropenia

Neutrophils help to clear pathogens and cellular debris, but can also cause collateral damage within inflamed tissues. Prolonged neutrophil residency within an inflammatory niche can exacerbate tissue pathology. Using both genetic and pharmacological approaches, we show that BCL-XL is required for the persistence of neutrophils within inflammatory sites in mice. We demonstrate that a selective BCL-XL inhibitor (A-1331852) has therapeutic potential by causing apoptosis in inflammatory human neutrophils ex vivo. Moreover, in murine models of acute and chronic inflammatory disease, it reduced inflammatory neutrophil numbers and ameliorated tissue pathology. In contrast, there was minimal effect on circulating neutrophils. Thus, we show a differential survival requirement in activated neutrophils for BCL-XL and reveal a new therapeutic approach to neutrophil-mediated diseases.

CD300a contributes to the resolution of articular inflammation triggered by MSU crystals by controlling neutrophil apoptosis.

Gout is an inflammatory disease triggered by deposition of monosodium urate (MSU) crystals in the joints, resulting in high neutrophil influx and pain. Here, we studied the role of the inhibitory receptor CD300a in the resolution process in a murine model of gout. We found increased CD300a expression on neutrophils emigrated to the joint. When compared to WT mice, CD300a-/- mice had persistent neutrophil influx till 24hr after MSU injection. This was associated with increased concentration of IL-1β and greater tissue damage in the joints of CD300a-/- mice. There was an increase in the percentage of apoptotic neutrophils in the synovial lavage of WT mice, as compared to CD300a-/- mice. This difference was reflected in the decline of efferocytic events in the synovial cavity of CD300a-/- mice 24hr after MSU injection. A CD300a agonistic antibody was shown, for the first time, to increase apoptosis of human neutrophils, and this was associated with cleavage of caspase-8. In conclusion, our results reveal an important role of CD300a in the control of leucocyte infiltration, IL-1β production and caspase-8cleavage in neutrophils, contributing to the resolution of inflammation triggered by MSU injection.

Upregulated PD-L1 delays human neutrophil apoptosis and promotes lung injury in an experimental mouse model of sepsis

AbstractPD-L1 is a ligand for PD-1, and its expression has been shown to be upregulated in neutrophils harvested from septic patients. However, the effect of PD-L1 on neutrophil survival and sepsis-induced lung injury remains largely unknown. In this study, PD-L1 expression correlated negatively with rates of apoptosis in human neutrophils harvested from patients with sepsis. Coimmunoprecipitation assays on control neutrophils challenged with interferon-γ and LPS showed that PD-L1 complexes with the p85 subunit of phosphatidyl 3-kinase (PI3K) to activate AKT-dependent survival signaling. Conditional CRE/LoxP deletion of neutrophil PD-L1 in vivo further protected against lung injury and reduced neutrophil lung infiltration in a cecal ligation and puncture (CLP) experimental sepsis animal model. Compared with wild-type animals, PD-L1–deficient animals presented lower levels of plasma tumor necrosis factor-α and interleukin-6 (IL-6) and higher levels of IL-10 after CLP, and reduced 7-day mortality in CLP PD-L1–knockout animals. Taken together, our data suggest that increased PD-L1 expression on human neutrophils delays cellular apoptosis by triggering PI3K–dependent AKT phosphorylation to drive lung injury and increase mortality during clinical and experimental sepsis.

Sialic acid-binding immunoglobulin-like lectin 9 as a potential therapeutic target for chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) has become the third-leading cause of death worldwide, which is a severe economic burden to the healthcare system. Chronic bronchitis is the most common condition that contributes to COPD, both locally and systemically. Neutrophilic inflammation predominates in the COPD airway wall and lumen. Logically, repression of neutrophilia is an essential fashion to COPD treatment. However, currently available anti-neutrophilic therapies provide little benefit in COPD patients and may have serious side effects. Thus, there is an urgent need to explore an effective and safe anti-neutrophilic approach that might delay progression of the disease. Sialic acid-binding immunoglobulin-like lectin (Siglec)-9 is a member of the Siglec cell surface immunoglobulin family. It is noteworthy that Siglec-9 is highly expressed on human neutrophils and monocytes. Ligation of Siglec-9 by chemical compounds or synthetic ligands induced apoptosis and autophagic-like cell death in human neutrophils. Furthermore, administration of antibody to Siglec-E, mouse functional ortholog of Siglec-9, restrained recruitment and activation of neutrophils in mouse models of airway inflammation in vivo. Given the critical role that neutrophils play in chronic bronchitis and emphysema, targeting Siglec-9 could be beneficial for the treatment of COPD, asthma, fibrosis, and related chronic inflammatory lung diseases.

Влияние хлорида лития на активацию нейтрофилов при развитии синдрома системного воспалительного ответа у пациентов после операций на сердце с использованием аппарата искусственного кровообращения

Цель исследования - изучение in vitro действия хлорида лития на активность нейтрофилов человека при действии сывороток пациентов с синдромом системного воспалительного ответа, развившемся после операций на сердце с искусственным кровообращением. Методика. Исследование проводили in vitro на нейтрофилах, выделенных из крови 6 здоровых доноров. Нейтрофилы активировали при помощи сыворотки пациентов с синдромом системного воспалительного ответа (ССВО), перенесших операции на сердце с искусственным кровообращением (ИК). Активность нейтрофилов оценивали с использованием флуоресцентных антител к маркерам дегрануляции CD11b и CD66b. Уровень апоптоза и некроза нейтрофилов оценивали через 22 ч после выделения из крови здоровых доноров; количественная оценка была проведена с использованием аннексина V и иодистого пропидия на проточном цитофлуориметре. Интактные и активированные нейтрофилы обрабатывали раствором хлорида лития в концентрациях 0,3; 3,0 и 9,0 мМ. Результаты. Инкубация нейтрофилов с сывороткой крови пациентов с ССВО после операций на сердце с ИК увеличивала экспрессию CD11b в 1,5 раза и экспрессию CD66b в 1,4 раза в сравнении с экспрессией на интактных нейтрофилах. Инкубация нейтрофилов с сывороткой крови пациентов с ССВО и раствором хлорида лития в концентрациях 3,0 и 9,0 мМ приводило к статистически значимому снижению уровня экспрессии CD11b CD66b на поверхности нейтрофилов в сравнении с активированными контрольными. Установлено, что хлорид лития в концентрациях 3,0 и 9,0 мМ возвращал уровни экспрессии CD11b и CD66b на активированных нейтрофилах к уровню экспрессии на интактных нейтрофилах. В концентрации 0,3 мМ хлорид лития, используемый при инкубации с активированными нейтрофилами, не вызывал значимого снижения экспрессии CD11b и CD66b относительно контрольных активированных нейтрофилов. Экспрессия CD11b и CD66b на активированных нейтрофилах при их инкубации с хлоридом лития в концентрации 0,3 мМ была значимо выше относительно экспрессии данных молекул на интактных нейтрофилах. Сыворотка пациентов с развившемся ССВО снижала спонтанный апоптоз нейтрофилов, а раствор хлорида лития в концентрации 3,0 или 9,0 мМ, добавленный в среду инкубации, увеличивал способность нейтрофилов к спонтанному апоптозу. Заключение. Хлорид лития оказывал противовоспалительный эффект снижал дегрануляцию и активацию нйтрофилов посредством уменьшения уровня экспрессии молекул CD11b и CD66b на поверхности нейтрофилов, которые предварительно были активированы сыворотками пациентов с ССВО. В концентрации 3,0 мМ и выше хлорид лития индуцировал спонтанный апоптоз нейтрофилов, активированных сыворотками пациентов с ССВО после операций на сердце с ИК. The aim of this work was to study the anti-inflammatory effect of lithium chloride on human neutrophils in vitro under the action of the serum of patients with systemic inflammatory response syndrome (SIRS), which developed after on-pump cardiac surgery. Methods. The study was performed on neutrophils isolated from the blood of five healthy donors, which was activated using serum from patients with SIRS. Neutrophil activity was assessed using fluorescent antibodies to CD11b and CD66b degranulation markers. The level of apoptosis and necrosis of human neutrophils was evaluated 22 hours after isolation. Quantification was performed using annexin V and propidium iodide on a flow cytometer. Intact and activated neutrophils were treated with 0.3, 3.0 аnd 9.0 mM lithium chlorides. Results. Incubation of neutrophils with the blood serum of patients with SIRS after on-pump cardiac surgery increased the expression of CD11b by 1.5 times and the expression of CD66b by 1.4 times compared to expression on intact neutrophils. Incubation of neutrophils with blood serum of patients with SIRS and 3.0 and 9.0 mM lithium chloride solutions led to a statistically significant decrease in the level of expression of CD11b CD66b on the surface of neutrophils in comparison with control activated neutrophils. It was found that 3.0 and 9.0 mM lithium chloride solutions returned the expression levels of CD11b and CD66b on activated neutrophils to the expression level on intact neutrophils. 0.3 mM of lithium chloride, used during incubation with activated neutrophils, did not cause a significant decrease in the expression of CD11b and CD66b relative to control activated neutrophils. The expression of CD11b and CD66b on activated neutrophils during their incubation with 0.3 mM of lithium chloride was significantly higher relative to the expression of these molecules on intact neutrophils. The serum of patients with advanced SIRS decreased the ability of neutrophils to spontaneous apoptosis. 3.0 or 9.0 mM lithium chloride solutions added to the incubation medium increased the ability of neutrophils to spontaneous apoptosis. Conclusion. Lithium chloride reduced the degranulation and activation of neutrophils by reducing the expression level of CD11b and CD66b molecules on the surface of neutrophils that were previously activated by the serum of patients with SIRS. This effect determines the anti-inflammatory influence of lithium chloride. Lithium chloride at 3.0 mM and higher induced spontaneous apoptosis of neutrophils activated by the serum of patients with SIRS after on-pump cardiac surgery.

The Effect of Lithium Chloride on Neutrophil Activation on Exposure to Serum of Patients with Septic Shock

The aim of the study: to examine the anti-inflammatory effect of lithium chloride by exposing the human neutrophils to serum of patients with septic shockin vitro.Material and methods. The study was carried out on neutrophils extracted from the blood of 6 healthy donors, which were activated with serum from patients with septic shock. The neutrophil activity was evaluated with fluorescent antibodies to the CD11b and CD66b markers of degranulation. The level of human neutrophil apoptosis and necrosis was assessed 22 hours after extraction; quantitative assessment was made using annexin V and propidium iodide with flow cytofluorimetry. Intact and activated neutrophils were treated with 0.3, 3.0 and 9.0 mmol lithium chloride solution.Results. The level of CD11b expression on the surface of intact neutrophils (healthy donors) was 3434.50 [3311.0-3799.0] arbitrary fluorescence units (AFU). Incubation of neutrophils with serum of patients with septic shock increased CD11b expression 2.5 times to 8589.0 [7279.0-11258.0] AFU (P=0.005) vs intact leukocytes, and increased CD66b expression 2.7 times up to 27 600.0 [22 999.0-28 989.0] AFU ((P=0.005) vs intact neutrophils. Lithium chloride in concentrations of 0.3, 3.0 and 9.0 mmol in a dose-dependent manner reduced the level of expression of CD11b and CD66b molecules on the surface of activated neutrophils. Septic serum reduced spontaneous neutrophil apoptosis, and 3.0 mmol and higher lithium chloride solution induced spontaneous neutrophil apoptosis.Conclusion. Lithium chloride reduces the activation of neutrophils preactivated by serum of patients with septic shock, reduces expression of CD11b and CD66b molecules on the neutrophil surface, inhibiting the process of their activation (degranulation). Lithium chloride in concentration of 3.0 mmol and higher is able to induce spontaneous apoptosis of neutrophils activated by serum of patients with septic shock.

Evaluation of the anti-inflammatory effects of synthesised tanshinone I and isotanshinone I analogues in zebrafish.

During inflammation, dysregulated neutrophil behaviour can play a major role in a range of chronic inflammatory diseases, for many of which current treatments are generally ineffective. Recently, specific naturally occurring tanshinones have shown promising anti-inflammatory effects by targeting neutrophils in vivo, yet such tanshinones, and moreover, their isomeric isotanshinone counterparts, are still a largely underexplored class of compounds, both in terms of synthesis and biological effects. To explore the anti-inflammatory effects of isotanshinones, and the tanshinones more generally, a series of substituted tanshinone and isotanshinone analogues was synthesised, alongside other structurally similar molecules. Evaluation of these using a transgenic zebrafish model of neutrophilic inflammation revealed differential anti-inflammatory profiles in vivo, with a number of compounds exhibiting promising effects. Several compounds reduce initial neutrophil recruitment and/or promote resolution of neutrophilic inflammation, of which two also result in increased apoptosis of human neutrophils. In particular, the methoxy-substituted tanshinone 39 specifically accelerates resolution of inflammation without affecting the recruitment of neutrophils to inflammatory sites, making this a particularly attractive candidate for potential pro-resolution therapeutics, as well as a possible lead for future development of functionalised tanshinones as molecular tools and/or chemical probes. The structurally related β-lapachones promote neutrophil recruitment but do not affect resolution. We also observed notable differences in toxicity profiles between compound classes. Overall, we provide new insights into the in vivo anti-inflammatory activities of several novel tanshinones, isotanshinones, and structurally related compounds.

Inhibition of ErbB kinase signalling promotes resolution of neutrophilic inflammation.

Neutrophilic inflammation with prolonged neutrophil survival is common to many inflammatory conditions, including chronic obstructive pulmonary disease (COPD). There are few specific therapies that reverse neutrophilic inflammation, but uncovering mechanisms regulating neutrophil survival is likely to identify novel therapeutic targets. Screening of 367 kinase inhibitors in human neutrophils and a zebrafish tail fin injury model identified ErbBs as common targets of compounds that accelerated inflammation resolution. The ErbB inhibitors gefitinib, CP-724714, erbstatin and tyrphostin AG825 significantly accelerated apoptosis of human neutrophils, including neutrophils from people with COPD. Neutrophil apoptosis was also increased in Tyrphostin AG825 treated-zebrafish in vivo. Tyrphostin AG825 decreased peritoneal inflammation in zymosan-treated mice, and increased lung neutrophil apoptosis and macrophage efferocytosis in a murine acute lung injury model. Tyrphostin AG825 and knockdown of egfra and erbb2 by CRISPR/Cas9 reduced inflammation in zebrafish. Our work shows that inhibitors of ErbB kinases have therapeutic potential in neutrophilic inflammatory disease.

ROCK Inhibition Drives Resolution of Acute Inflammation by Enhancing Neutrophil Apoptosis.

Uncontrolled inflammation leads to tissue damage and it is central for the development of chronic inflammatory diseases and autoimmunity. An acute inflammatory response is finely regulated by the action of anti-inflammatory and pro-resolutive mediators, culminating in the resolution of inflammation and restoration of homeostasis. There are few studies investigating intracellular signaling pathways associated with the resolution of inflammation. Here, we investigate the role of Rho-associated kinase (ROCK), a serine/threonine kinase, in a model of self-resolving neutrophilic inflammatory. We show that ROCK activity, evaluated by P-MYPT-1 kinetics, was higher during the peak of lipopolysaccharide-induced neutrophil influx in the pleural cavity of mice. ROCK inhibition by treatment with Y-27632 decreased the accumulation of neutrophils in the pleural cavity and was associated with an increase in apoptotic events and efferocytosis, as evaluated by an in vivo assay. In a model of gout, treatment with Y-27632 reduced neutrophil accumulation, IL-1β levels and hypernociception in the joint. These were associated with reduced MYPT and IκBα phosphorylation levels and increased apoptosis. Finally, inhibition of ROCK activity also induced apoptosis in human neutrophils and destabilized cytoskeleton, extending the observed effects to human cells. Taken together, these data show that inhibition of the ROCK pathway might represent a potential therapeutic target for neutrophilic inflammatory diseases.

Inhibition of the sphingosine-1-phosphate pathway promotes the resolution of neutrophilic inflammation.

Sphingosine-1-phosphate (S1P) is an important sphingolipid derived from plasma membrane and has a known role in productive phase of inflammation, but its role in neutrophil survival and resolution phase of inflammation is unknown. Here, we investigated the effects of inhibition of S1P receptors and the blockade of S1P synthesis in BALB/c mice and human neutrophils. S1P and S1PR1-3 receptors expression were increased in cells from the pleural cavity stimulated with LPS. Using different antagonists of S1PRs and inhibitors of different steps of the metabolic pathway of S1P production, we show that S1P and its receptors are involved in regulating neutrophil survival and resolution of inflammation in the pleural cavity. Given the role of the S1P-S1PR axis in resolution of inflammation, we sought to identify whether blockade at different levels of the sphingosine-1-phosphate synthesis pathway could affect neutrophil survival in vitro. Inhibitors of the S1P pathway were also able to induce human neutrophil apoptosis. In addition, blockade of S1P synthesis or its receptor facilitated the efferocytosis of apoptotic neutrophil. Taken together, our data demonstrate a fundamental role for S1P in regulating the outcome of inflammatory responses, and position S1P-S1PR axis as a potential target for treatment of neutrophilic inflammation.

The influence of melatonin on apoptosis of human neutrophils

Aim: Melatonin (Mel) besides its main role in circadian and seasonal rhythm coordination, plays a role in immunoregulation and inflammatory responses. The melatonin’s ability to modulate apoptosis is one of its important roles related to its effect on immune system but the exact effect of its action and the mechanisms of apoptosis control by melatonin remain still unclear. The goal of our study was to examine the involvement of melatonin in the apoptosis of human neutrophils in vitro and possible mechanisms of this action. Material/Methods: We measured the effect of melatonin on the spontaneous and TNF-α-induced apoptosis of human neutrophils using propidium iodide and Annexin-V and on caspase-3 activation, apoptosis-related surface antigen expressions, intracellular reactive oxygen species (ROS) generation and cytochrome c release using flow cytometry and commercial reagents. Results: Melatonin does not affect spontaneous apoptosis of human neutrophils and mitochondrial cytochrome c release but protects the cells from the significant rise of TNF-α-induced apoptosis and cytochrome c release. Intracellular ROS generation in PMA-stimulated neutrophils did not change after the influence of melatonin but the significant drop of ROS generation in neutrophils stimulated with TNF- α was upregulated to the control level after preincubation of the neutrophils with melatonin. Melatonin did not change significantly Fas, Fas-L and active caspase-3 expressions in neutrophils. Conclusions: Melatonin does not affect the spontaneous apoptosis, however, inhibits TNF-α-induced apoptosis of human neutrophils. Our findings suggest that the intrinsic pathway of the process is a result of the melatonin induced mitochondrial alterations.

Effects of endotoxin/lipopolysaccharide on early apoptosis of human neutrophil through PIM3

Objective: To explore the effects of endotoxin/lipopolysaccharide (LPS) on early apoptosis of human neutrophil through PIM3. Methods: Venous blood samples were collected from a healthy adult volunteer to isolate neutrophils. The neutrophils were divided into control group, LPS group, and LPS+ PIM447 group according to the random number table. No treatment was given to the cells in control group. The cells in LPS group underwent LPS stimulation (1 μL, 1 μg/mL). The cells in LPS+ PIM447 group underwent PIM447 (1 μL, final amount-of-substance concentration of 5 μmol/L) intervention 30 min before having the same LPS stimulation as that in LPS group. After conventional culture for 1 h, the early cell apoptosis rate was determined with flow cytometer; the generation level of reactive oxygen species (ROS) was assessed with dihydrogenrhodamine 123 fluorescent probe staining method; and the level of PIM3 was detected by Western blotting. After conventional culture for 2 h, the cell chemotaxis distance was measured by agarose chemotaxis cell model. The sample numbers of each group in the 4 experiments were all 5. Data were processed with one-way analysis of variance and Student-Newman-Keuls test. Results: (1) The early apoptosis rate of cells in LPS group [(0.891±0.012)%] was close to that in control group [(1.351±0.183)%, P>0.05)]. The early apoptosis rate of cells in LPS+ PIM447 group [(82.057±0.121)%] was higher than that in LPS group (P<0.01). (2) The cell chemotaxis distance of cells in LPS group [(984±5) μm] was significantly shorter than that in control group [(2 241±7) μm, P<0.01]. The cell chemotaxis distance of cells in LPS+ PIM447 group [(1 785±11) μm]was significantly longer than that in LPS group (P<0.05). (3) The generation level of ROS in cells of LPS group was significantly higher than that in control group (P<0.05). The generation level of ROS in cells of LPS+ PIM447 group was significantly lower than that in LPS group (P<0.05). (4) The expression level of PIM3 in cells of LPS group (1.297±0.015) was significantly higher than that in control group (0.789±0.021, P<0.05). The expression level of PIM3 in cells of LPS+ PIM447 group (0.731±0.011) was significantly lower than that in LPS group (P<0.05). Conclusions: LPS stimulation can reduce the early apoptosis of human neutrophils. Pre-intervention with PIM447 can significantly increase the early apoptosis of neutrophils after LPS stimulation, recover the chemotaxis, and inhibit the production of ROS. The mechanism may be related to LPS promoting the expression of PIM3.