Respiratory burst in neutrophils from asthmatic patients

Gallic Acid Protects from Sepsis-Induced Acute Lung Injury

Sepsis, a leading global cause of morbidity and mortality, involves multiple organ dysfunction syndromes driven by free radical-mediated processes. Uncontrolled inflammation in early sepsis stages can lead to acute lung injury (ALI). Activated leukocytes generate reactive oxygen species, contributing to sepsis development. Gallic acid, a phenolic compound, is known for its antimicrobial properties. This study aims to observe gallic acid's protective and restorative effect on the lungs in an experimental sepsis model. Male Wistar albino rats were subjected to a feces intraperitoneal injection procedure (FIP) to induce sepsis. Four groups were formed: normal control, FIP alone, FIP with saline, and FIP with gallic acid. Gallic acid was administered intraperitoneally at 20 mg/kg/day. Blood samples were collected for biochemical analysis, and computed tomography assessed lung tissue histopathologically and radiologically. Gallic acid significantly decreased malondialdehyde, IL-6, IL-1β, TNF-α, CRP levels, oxidative stress, and inflammation indicators. Lactic acid levels decreased, suggesting improved tissue oxygenation. Histopathological examinations revealed reduced lung damage in the gallic-acid-treated group. Computed tomography confirmed lower lung density, indicating less severe inflammation. Arterial blood gas analysis demonstrated improved oxygenation in gallic-acid-treated rats. Gallic acid exhibited anti-inflammatory and antioxidant effects, reducing markers of systemic inflammation and oxidative stress. The findings support its potential to protect against ALI during sepsis. Comparable studies underline gallic acid's anti-inflammatory properties in different tissues. Early administration of gallic acid in sepsis models demonstrated protective effects against ALI, emphasizing its potential as an adjunct therapy to mitigate adverse outcomes. The study proposes gallic acid to reduce mortality rates and decrease the need for mechanical ventilation during sepsis-induced ALI.

Regulation and directed inhibition of ECP production by human neutrophils

Background

Neutrophils are involved in the pathophysiology of allergic asthma, where the Eosinophil Cationic Protein (ECP) is a critical inflammatory mediator. Although ECP production is attributed to eosinophils, we reported that ECP is also present in neutrophils from allergic patients where, in contrast to eosinophils, it is produced in an IgE-dependent manner. Given the key role of ECP in asthma, we investigated the molecular mechanisms involved in ECP production as well as the effects induced by agonists and widely used clinical approaches. We also analyzed the correlation between ECP production and lung function.

Methods

Neutrophils from allergic asthmatic patients were challenged with allergens, alone or in combination with cytokines, in the presence of cell-signaling inhibitors and clinical drugs. We analyzed ECP levels by ELISA and confocal microscopy. Lung function was assessed by spirometry.

Results

IgE-mediated ECP release is dependent on phosphoinositide 3-kinase, the extracellular signal-regulated kinase (ERK1/2) and the production of reactive oxygen species by NADPH-oxidase. Calcineurin phosphatase and the transcription factor NFAT are also involved. ECP release is enhanced by the cytokines interleukin (IL)-5 and granulocyte macrophage-colony stimulating factor, and inhibited by interferon-γ, IL-10, clinical drugs (formoterol, tiotropium and budesonide) and allergen-specific IT. We also found an inverse correlation between asthma severity and ECP levels.

Conclusions

Our results suggest the molecular pathways involved in ECP production and potential therapeutic targets. We also provide a new method to evaluate disease severity in asthmatic patients based on the quantification of in vitro ECP production by peripheral neutrophils.

Targeted inhibition of allergen-induced histamine production by neutrophils

Histamine is a critical inflammatory mediator in allergic diseases. We showed in a previous work that neutrophils from allergic patients produce histamine in response to allergens to which the patients were sensitized. Here, we investigate the molecular mechanisms involved in this process using peripheral blood neutrophils. We challenged these cells in vitro with allergens and analyzed histamine release in the culture supernatants. We also explored the effect of common therapeutic drugs that ameliorate allergic symptoms, as well as allergen-specific immunotherapy. Additionally, we examined the expression of histidine decarboxylase and diamine oxidase, critical enzymes in the metabolism of histamine, under allergen challenge. We show that allergen-induced histamine release is dependent on the activation of the phosphoinositide 3-kinase, mitogen-activated protein kinase p38, and extracellular signal-regulated kinase 1/2 signaling pathways. We also found a contribution of the phosphatase calcineurin to lesser extent. Anti-histamines, glucocorticoids, anti-M3-muscarinic receptor antagonists, and mainly β₂ -receptor agonists abolished the allergen-dependent histamine release. Interestingly, allergen-specific immunotherapy canceled the histamine release through the downregulation of histidine decarboxylase expression. Our observations describe novel molecular mechanisms involved in the allergen-dependent histamine release by human neutrophils and provide new targets to inhibit histamine production.

The peripheral blood inflammatory patterns in the control levels of asthma in children

OBJECTIVE

Asthma is the most common chronic inflammatory disease of childhood, but there are no useful and easily accessible laboratory tests routinely used in the diagnosis and follow-up of this disease in children. Therefore, this study aimed to investigate the roles of white blood cell (WBC) count, platelet count, mean platelet volume (MPV), and eosinophil percentage as full blood count inflammatory markers in evaluating the control level and follow-up of asthma in the pediatric age group.

METHODS

A retrospective review of patient records and files of 3,580 patients diagnosed with asthma at the University of Health Sciences in Ankara, Turkey was performed. Patients who met inclusion/exclusion criteria were divided into two groups based on the asthma control level: controlled and uncontrolled. Laboratory data were compared according to the asthma control levels, drug use status, and atopy status of the patients.

RESULTS

A total of 348 patients between 4 and 18 years of age, who were followed-up with the diagnosis of asthma, were included in this study. A significant difference was found between the controlled and uncontrolled groups of asthma patients in terms of the eosinophil percentage (mean ± SD, respectively; 3.493 ± 2.24; 4.992 ± 3.43; p = .003). When patients were grouped according to their asthma control levels and atopy status, only the eosinophil percentages were different in the logistic regression analysis (odds ratio = 1.276, 95% confidence interval = 1.113-1.462).

CONCLUSION

Our study showed that the percentage of eosinophils can be used as an asthma control parameter, but additional prospective studies would be desirable to confirm our results.

Modeling the pasture-associated severe equine asthma bronchoalveolar lavage fluid proteome identifies molecular events mediating neutrophilic airway inflammation

Background: Pasture-associated severe equine asthma is a warm season, environmentally-induced respiratory disease characterized by reversible airway obstruction, persistent and non-specific airway hyper-responsiveness, and chronic neutrophilic airway inflammation. During seasonal exacerbation, signs vary from mild to life-threatening episodes of wheezing, coughing, and chronic debilitating labored breathing.

Purpose: In human asthma, neutrophilic airway inflammation is associated with more severe and steroid-refractory asthma phenotypes, highlighting a need to decipher the mechanistic basis of this disease characteristic. We hypothesize that the collective biological activities of proteins in bronchoalveolar lavage fluid (BALF) of horses with pasture-associated severe asthma predict changes in neutrophil functions that contribute to airway neutrophilic inflammation.

Methods: Using shotgun proteomics, we identified 1,003 unique proteins in cell-free BALF from six horses experiencing asthma exacerbation and six control herdmates. Contributions of each protein to ten neutrophil functions were modeled using manual biocuration to determine each protein’s net effect on the respective neutrophil functions.

Results: A total of 417 proteins were unique to asthmatic horses, 472 proteins were unique to control horses (p<0.05), and 114 proteins were common in both groups. Proteins whose biological activities are responsible for increasing neutrophil migration, chemotaxis, cell spreading, transmigration, and infiltration, which would collectively bring neutrophils to airways, were over-represented in the BALF of asthmatic relative to control horses. By contrast, proteins whose biological activities support neutrophil activation, adhesion, phagocytosis, respiratory burst, and apoptosis, which would collectively shorten neutrophil lifespan, were under-represented in BALF of asthmatic relative to control horses. Interaction networks generated using Ingenuity^® Pathways Analysis further support the results of our biocuration.

Conclusion: Congruent with our hypothesis, the collective biological functions represented in differentially expressed proteins of BALF from horses with pasture-associated severe asthma support neutrophilic airway inflammation. This illustrates the utility of systems modeling to organize functional genomics data in a manner that characterizes complex molecular events associated with clinically relevant disease.

Accelerated reactivity of blood granulocytes in patients with atopic bronchial asthma out of exacerbation

Reactive oxygen species (ROS) are important in bronchial asthma (BA) pathogenesis owing to accumulation of activated granulocytes in the lungs. But the ROS-producing activity of the cells is insufficiently understood in the blood of BA patients. This study analyzes the kinetics of phagocyte respiratory burst in the blood to improve the methods of BA patients monitoring. Patients with atopic BA out of exacerbation (n=60) and healthy controls (n=43) were recruited. The time-course of respiratory response to opsonized zymosan (OZ) was recorded in the whole blood using luminol-dependent chemiluminescence (CL), and its activation kinetics (lag-time, rate, amplitude, ROS production) was calculated. The discriminative power of ROS generation kinetics was defined by Receiver Operating Characteristic (ROC) curve analysis. Standard physiological respiratory parameters of patients did not differ from the controls. More rapid response to OZ was recorded in BA patient samples versus the controls. The primed state of phagocytes in the blood of BA patients was corroborated by significant weakening formyl peptide priming effect. The adhesion of granulocytes to cultured human endothelial cells was two-fold higher in BA patients versus controls. ROC curve analysis exhibited good discriminative effectiveness of the CL kinetics to compare BA individuals with the controls. The highest power (86% sensitivity and 90% specificity) was achieved at a linear combination of the parameters. We assume that the assessment of phagocyte reactivity based on the analysis of the response kinetic profile is a good test for monitoring of the state in BA patients.

Neutrophils in asthma--a review

Asthma is a chronic inflammatory disease, with an array of cells involved in the pathogenesis of the disease. The role of neutrophils in the development of bronchial asthma is found to be complex, as they may trigger activation of immunocompetent cells and are a potent source of free oxygen radicals and enzymes participating in airway remodeling. The review highlights the role of neutrophils in bronchial asthma.

Prophylactic antioxidant potential of gallic Acid in murine model of sepsis

Present study is to investigate the effect of Gallic acid pretreatment on survival of septic animals and oxidative stress in different organs like lungs, liver, kidney, spleen, and vascular dysfunction of mice. Sepsis was induced by cecal ligation and puncture (CLP) in healthy adult male albino mice (25–30 g) and was divided into 3 groups each consisting of 6 animals, that is, sham-operated (SO group (Group I), SO + sepsis (Group II), and Gallic acid + sepsis (Group III)). Group III animals were pretreated with Gallic acid at the dose rate of 20 mg/kg body weight for 2 days before induction of sepsis. Animals were sacrificed on 8th day and the tissue samples were obtained for further investigation on lipid peroxidation (LPO), malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione reductase (GSH). Gallic acid pretreatment significant (P < 0.05) reduces kidney, spleen, liver, and lungs' malondialdehyde level in septic mice. However, it fails to improve reduced glutathione level in all given organs, while, Gallic acid pretreated mice showed significant improvement in SOD activity of kidney and spleen when compared to septic mice. Finally, the beneficial effects of Gallic acid pretreatment in sepsis are evident from the observations that Gallic acid partially restored SOD and catalase activity and completely reversed lipid peroxidation. Further studies are required to find out the possible mechanisms underlying the beneficial effects of Gallic acid on large population.

Effects of diphenyl diselenide on oxidative stress induced by sepsis in rats

Sepsis is a potentially deadly complication that can be caused by different factors. Actually, it is known that oxidative stress is involved in the pathogenesis of sepsis. Thus, the aim of this study was to evaluate the effect of diphenyl diselenide (PhSe)(2), an emergent compound, on oxidative stress parameters induced by sepsis in rats. Animals were pre-injected with (PhSe)(2) or vehicle. Twenty-four hours later, sepsis was induced by cecal ligation puncture (CLP). After 12 h, liver was taken for thiobarbituric acid reactive species (TBARS) measurement, δ-aminolevunic acid dehydratase (δ-ALA-D), Cu/Zn superoxide dismutase (Cu/Zn SOD) and catalase (CAT) activities assay. The sepsis increased TBARS, inhibited δ-ALA-D, activated Cu/Zn SOD and had a tendency to decrease CAT activity. However, (PhSe)(2) prevented the TBARS formation, but did not prevent the inhibition of δ-ALA-D activity in the animals with damage. Thus, this study showed that (PhSe)(2) partially prevents the oxidative stress induced by sepsis, indicating the potential of this compound as a treatment for this pathology. Nevertheless, more tests should be performed to confirm the hypothesis suggested here.

The tripeptide feG regulates the production of intracellular reactive oxygen species by neutrophils

BACKGROUND

The D-isomeric form of the tripeptide FEG (feG) is a potent anti-inflammatory agent that suppresses type I hypersensitivity (IgE-mediated allergic) reactions in several animal species. One of feG's primary actions is to inhibit leukocyte activation resulting in loss of their adhesive and migratory properties. Since activation of neutrophils is often associated with an increase in respiratory burst with the generation of reactive oxygen species (ROS), we examined the effect of feG on the respiratory burst in neutrophils of antigen-sensitized rats. A role for protein kinase C (PKC) in the actions of feG was evaluated by using selective isoform inhibitors for PKC.

RESULTS

At 18 h after antigen (ovalbumin) challenge of sensitized Sprague-Dawley rats a pronounced neutrophilia occurred; a response that was reduced in animals treated with feG (100 microg/kg). With antigen-challenged animals the protein kinase C (PKC) activator, PMA, significantly increased intracellular ROS of circulating neutrophils, as determined by flow cytometry using the fluorescent probe dihydrorhodamine-123. This increase was prevented by treatment with feG at the time of antigen challenge. The inhibitor of PKCdelta, rottlerin, which effectively prevented intracellular ROS production by circulating neutrophils of animals receiving a naïve antigen, failed to inhibit PMA-stimulated ROS production if the animals were challenged with antigen. feG treatment, however, re-established the inhibitory effects of the PKCdelta inhibitor on intracellular ROS production. The extracellular release of superoxide anion, evaluated by measuring the oxidative reduction of cytochrome C, was neither modified by antigen challenge nor feG treatment. However, hispidin, an inhibitor of PKCbeta, inhibited the release of superoxide anion from circulating leukocytes in all groups of animals. feG prevented the increased expression of the beta1-integrin CD49d on the circulating neutrophils elicited by antigen challenge.

CONCLUSION

feG reduces the capacity of circulating neutrophils to generate intracellular ROS consequent to an allergic reaction by preventing the deregulation of PKCdelta. This action of feG may be related to the reduction in antigen-induced up-regulation of CD49d expression on circulating neutrophils.

Superoxide release and cellular gluthatione peroxidase activity in leukocytes from children with persistent asthma

Asthma is an inflammatory condition characterized by the involvement of several mediators, including reactive oxygen species. The aim of the present study was to investigate the superoxide release and cellular glutathione peroxidase (cGPx) activity in peripheral blood granulocytes and monocytes from children and adolescents with atopic asthma. Forty-four patients were selected and classified as having intermittent or persistent asthma (mild, moderate or severe). The spontaneous or phorbol myristate acetate (PMA, 30 nM)-induced superoxide release by granulocytes and monocytes was determined at 0, 5, 15, and 25 min. cGPx activity was assayed spectrophotometrically. The spontaneous superoxide release by granulocytes from patients with mild (N = 15), moderate (N = 12) or severe (N = 6) asthma was higher at 25 min compared to healthy individuals (N = 28, P < 0.05, Duncan test). The PMA-induced superoxide release by granulocytes from patients with moderate (N = 12) or severe (N = 6) asthma was higher at 15 and 25 min compared to healthy individuals (N = 28, P < 0.05 in both times of incubation, Duncan test). The spontaneous or PMA-induced superoxide release by monocytes from asthmatic patients was similar to healthy individuals (P > 0.05 in all times of incubation, Duncan test). cGPx activity of granulocytes and monocytes from patients with persistent asthma (N = 20) was also similar to healthy individuals (N = 10, P > 0.05, Kruskal-Wallis test). We conclude that, under specific circumstances, granulocytes from children with persistent asthma present a higher respiratory burst activity compared to healthy individuals. These findings indicate a risk of oxidative stress, phagocyte auto-oxidation, and the subsequent release of intracellular toxic oxidants and enzymes, leading to additional inflammation and lung damage in asthmatic children.

Human neutrophils synthesize IL-8 in an IgE-mediated activation

It has been demonstrated that neutrophils are responsible for the release of large amounts of the inflammatory chemokine interleukin-8 (IL-8), associated with inflammation. To further define the mechanisms implicated, we have analyzed the response of human neutrophils from allergic patients to specific antigens or challenge with anti-immunoglobulin (Ig)E antibodies. Neutrophils showed a dose- and time-dependent production of IL-8. The release of the cytokine was parallel to expression of IL-8 mRNA analyzed by the polymerase chain reaction. This expression was transient-it occurred after 3 h of anti-IgE treatment and was maintained for 18 h. Trifluoperazine, EGTA, reduced nicotinamide adenine dinucleotide phosphate-oxidase inhibitors, and reactive oxygen species (ROS) scavengers inhibited IL-8 production, indicating a critical dependence of calcium and oxidative stress. Moreover, an inhibitory effect of cyclosporin A, an immunosuppressor that inhibits calcineurin activity, on IL-8 release and IL-8 mRNA expression was observed. This is the first evidence of the involvement of ROS and calcium/calcineurin in IgE-dependent IL-8 production. These findings open new perspectives into the functional role of neutrophils in IgE-associated diseases.