Neutrophil function and glutathione-peroxidase (GSH-px) activity in healthy individuals after treatment with N-acetyl-L-cysteine

Effects of N-Acetyl-L-Cystein Antioxidant on Ex Vivo Culture of Vitrified Premature Mouse Ovarian Tissue

Optimization of practical ways to obtain mature follicles from cryopreserved ovarian tissues, especially in patients suffering from ovarian dysfunction, is very important. In vitro ovarian tissue culture allows faster screening of follicle development and reduces follicle isolation damage. During ovarian tissue culture, controlling oxidative stress is critical to support better follicular development and less damage. Immature Naval Medical Research Institute (NMRI) mouse ovaries (8-days-old) were randomly distributed into four cultured groups; non-vitrified, vitrified, non-vitrified N-acetyl-L-cysteine (NAC)⁺, and vitrified NAC⁺. Ovaries of vitrified groups along with non-vitrified ovaries were cultured on agar gel in the presence or absence of NAC for 5 days. Afterward, morphological evaluations, mRNA expressions of Gdf9, Bmp6, Lif, Amh, Bax, and Bcl2 genes, malondialdehyde, and total antioxidant capacities were compared between four groups at the first and last day of culture. Good preservation of tissue integrity and an increase of follicular development were observed in all groups. In addition, the expression of Gdf9, Lif, Bax, and Bcl2 genes were increased and Amh was decreased in groups cultured in the presence of NAC compared to groups cultured without NAC. Although total antioxidant capacity was not significantly different between the experimental groups, the lipid peroxidation and apoptotic index were significantly reduced in the presence of NAC. Thus, it appears that NAC antioxidant acts as a contributory factor for the ex vivo culture of ovarian tissue and reduces oxidative stress, apoptotic index, and improves follicular development, especially in non-vitrified groups.

Preventing the development of severe COVID-19 by modifying immunothrombosis

BACKGROUND

COVID-19-associated acute respiratory distress syndrome (ARDS) is associated with significant morbidity and high levels of mortality. This paper describes the processes involved in the pathophysiology of COVID-19 from the initial infection and subsequent destruction of type II alveolar epithelial cells by SARS-CoV-2 and culminating in the development of ARDS.

MAIN BODY

The activation of alveolar cells and alveolar macrophages leads to the release of large quantities of proinflammatory cytokines and chemokines and their translocation into the pulmonary vasculature. The presence of these inflammatory mediators in the vascular compartment leads to the activation of vascular endothelial cells platelets and neutrophils and the subsequent formation of platelet neutrophil complexes. These complexes in concert with activated endothelial cells interact to create a state of immunothrombosis. The consequence of immunothrombosis include hypercoagulation, accelerating inflammation, fibrin deposition, migration of neutrophil extracellular traps (NETs) producing neutrophils into the alveolar apace, activation of the NLRP3 inflammazome, increased alveolar macrophage destruction and massive tissue damage by pyroptosis and necroptosis Therapeutic combinations aimed at ameliorating immunothrombosis and preventing the development of severe COVID-19 are discussed in detail.

Intermittent Hypoxia Affects the Spontaneous Differentiation In Vitro of Human Neutrophils into Long-Lived Giant Phagocytes

Previously we identified, for the first time, a new small-size subset of neutrophil-derived giant phagocytes (Gϕ) which spontaneously develop in vitro without additional growth factors or cytokines. Gϕ are CD66b(+)/CD63(+)/MPO(+)/LC3B(+) and are characterized by extended lifespan, large phagolysosomes, active phagocytosis, and reactive oxygen species (ROS) production, and autophagy largely controls their formation. Hypoxia, and particularly hypoxia/reoxygenation, is a prominent feature of many pathological processes. Herein we investigated Gϕ formation by applying various hypoxic conditions. Chronic intermittent hypoxia (IH) (29 cycles/day for 5 days) completely abolished Gϕ formation, while acute IH had dose-dependent effects. Exposure to 24 h (56 IH cycles) decreased their size, yield, phagocytic ability, autophagy, mitophagy, and gp91-phox/p22-phox expression, whereas under 24 h sustained hypoxia (SH) the size and expression of LC3B and gp91-phox/p22-phox resembled Gϕ formed in normoxia. Diphenyl iodide (DPI), a NADPH oxidase inhibitor, as well as the PI3K/Akt and autophagy inhibitor LY294002 abolished Gϕ formation at all oxygen conditions. However, the potent antioxidant, N-acetylcysteine (NAC) abrogated the effects of IH by inducing large CD66b(+)/LC3B(+) Gϕ and increased both NADPH oxidase expression and phagocytosis. These findings suggest that NADPH oxidase, autophagy, and the PI3K/Akt pathway are involved in Gϕ development.

Antioxidant and anti-inflammatory efficacy of NAC in the treatment of COPD: discordant in vitro and in vivo dose-effects: a review

In order to develop efficient therapeutic regimes for chronic obstructive pulmonary disease (COPD), N-acetylcysteine (NAC) has been tested as a medication which can suppress various pathogenic processes in this disease. Besides its well-known and efficient mucolytic action, NAC meets these needs by virtue of its antioxidant and anti-inflammatory modes of action. NAC is a thiol compound which by providing sulfhydryl groups, can act both as a precursor of reduced glutathione and as a direct ROS scavenger, hence regulating the redox status in the cells. In this way it can interfere with several signaling pathways that play a role in regulating apoptosis, angiogenesis, cell growth and arrest and inflammatory response. Overall, the antioxidant effects of NAC are well documented in in vivo and in vitro studies. It successfully inhibits oxidative stress at both high and low concentrations, under acute (in vitro) and chronic administration (in vivo). With regard to its anti-inflammatory action, in contrast, the effects of NAC differ in vivo and in vitro and are highly dose-dependent. In the in vitro settings anti-inflammatory effects are seen at high but not at low concentrations. On the other hand, some long-term effectiveness is reported in several in vivo studies even at low dosages. Increasing the dose seems to improve NAC bioavailability and may also consolidate some of its effects. In this way, the effects that are observed in the clinical and in vivo studies do not always reflect the success of the in vitro experiments. Furthermore, the results obtained with healthy volunteers do not always provide incontrovertible proof of its usefulness in COPD especially when number of exacerbations and changes in lung function are chosen as the primary outcomes. Despite these considerations and in view of the present lack of effective therapies to inhibit disease progression in COPD, NAC and its derivatives, because of their multiple molecular modes of action, remain promising medication once doses and route of administration are optimized.

Role of N-acetylcysteine in the management of COPD

The importance of the underlying local and systemic oxidative stress and inflammation in chronic obstructive pulmonary disease (COPD) has long been established. In view of the lack of therapy that might inhibit the progress of the disease, there is an urgent need for a successful therapeutic approach that, through affecting the pathological processes, will influence the subsequent issues in COPD management such as lung function, airway clearance, dyspnoea, exacerbation, and quality of life. N-acetylcysteine (NAC) is a mucolytic and antioxidant drug that may also influence several inflammatory pathways. It provides the sulfhydryl groups and acts both as a precursor of reduced glutathione and as a direct reactive oxygen species (ROS) scavenger, hence regulating the redox status in the cells. The changed redox status may, in turn, influence the inflammation-controlling pathways. Moreover, as a mucolytic drug, it may, by means of decreasing viscosity of the sputum, clean the bronchi leading to a decrease in dyspnoea and improved lung function. Nevertheless, as successful as it is in the in vitro studies and in vivo studies with high dosage, its actions at the dosages used in COPD management are debatable. It seems to influence exacerbation rate and limit the number of hospitalization days, however, with little or no influence on the lung function parameters. Despite these considerations and in view of the present lack of effective therapies to inhibit disease progression in COPD, NAC and its derivatives with their multiple molecular modes of action remain promising medication once doses and route of administration are optimized.

ROS generated by pollen NADPH oxidase provide a signal that augments antigen-induced allergic airway inflammation

Pollen exposure induces allergic airway inflammation in sensitized subjects. The role of antigenic pollen proteins in the induction of allergic airway inflammation is well characterized, but the contribution of other constituents in pollen grains to this process is unknown. Here we show that pollen grains and their extracts contain intrinsic NADPH oxidases. The pollen NADPH oxidases rapidly increased the levels of ROS in lung epithelium as well as the amount of oxidized glutathione (GSSG) and 4-hydroxynonenal (4-HNE) in airway-lining fluid. These oxidases, as well as products of oxidative stress (such as GSSG and 4-HNE) generated by these enzymes, induced neutrophil recruitment to the airways independent of the adaptive immune response. Removal of pollen NADPH oxidase activity from the challenge material reduced antigen-induced allergic airway inflammation, the number of mucin-containing cells in airway epithelium, and antigen-specific IgE levels in sensitized mice. Furthermore, challenge with Amb a 1, the major antigen in ragweed pollen extract that does not possess NADPH oxidase activity, induced low-grade allergic airway inflammation. Addition of GSSG or 4-HNE to Amb a 1 challenge material boosted allergic airway inflammation. We propose that oxidative stress generated by pollen NADPH oxidases (signal 1) augments allergic airway inflammation induced by pollen antigen (signal 2).

Effect of N-acetyl-cysteine on the hypoxic ventilatory response and erythropoietin production: linkage between plasma thiol redox state and O(2) chemosensitivity

Oxygen-sensing chemoreceptors contribute significantly to the regulation of the respiratory drive and arterial PO(2) levels. The hypoxic ventilatory response (HVR) decreases strongly with age and is modulated by prolonged hypoxia and physical exercise. Several earlier studies indicated that the regulation of the ventilatory response and erythropoietin (EPO) production by the respective oxygen sensors involves redox-sensitive signaling pathways, which are triggered by the O(2)-dependent production of reactive oxygen species. The hypothesis that HVR and EPO production are modulated by thiol compounds or changes in the plasma thiol-disulfide redox state (REDST) was investigated. It was demonstrated that both responses are enhanced by oral treatment with N-acetyl-cysteine (NAC) and that HVR is correlated with plasma thiol level and REDST. Results suggest the possibility that age-related changes in plasma REDST may account for the age-related changes in HVR.

N-acetylcysteine reduces respiratory burst but augments neutrophil phagocytosis in intensive care unit patients

OBJECTIVE

The antioxidant N-acetylcysteine (NAC) has been shown to attenuate septic tissue injury. To evaluate whether NAC affects host defense mechanisms in critically ill patients, thus predisposing to increased risk of infection, the current study focuses on neutrophil phagocytotic and burst activity after treatment with NAC.

DESIGN

Prospective, randomized, clinical trial.

SETTING

Twelve-bed operative intensive care unit in a university hospital.

PATIENTS

Thirty patients diagnosed with sepsis/systemic inflammatory response syndrome, or multiple trauma.

INTERVENTIONS

Patients were randomly assigned to receive either NAC (n = 15) for 4 days in increasing dosages (day 1: 6 g; day 2: 12 g; days 3 and 4: 18 g) or a mucolytic basis dosage of NAC (3 x 300 mg/day [control]; n = 15), respectively.

MEASUREMENTS AND MAIN RESULTS

Blood samples were taken before NAC high-dose infusion (day 1), after increasing doses of NAC (days 3 and 5) and 4 days after the last high-dose treatment (day 8). Neutrophil oxidative burst activity after stimulation with Escherichia coli and polymorphonuclear phagocytosis were determined in a flow cytometric assay. Baseline values of polymorphonuclear functions were comparable in both groups. NAC high-dose treatment resulted in a significantly improved phagocytosis activity compared with control patients. In contrast to this, polymorphonuclear burst activity was significantly reduced in the NAC high-dose treated group on day 3.

CONCLUSION

These findings suggest that infusion of NAC in high doses affects granulocyte functions in critically ill patients. Antimicrobial host defense requires the effective sequence of cell adhesion, phagocytosis, and bactericidal respiratory burst. The enhanced phagocytotic activity might be a compensatory mechanism in states of impaired respiratory burst to maintain tissue sterility. For certain mechanisms of disease, the effects observed might be favorable (e.g., ischemia/reperfusion, endothelial cell activation), for others (infection) this might be detrimental.

Effects in vitro of several antioxidants on the natural killer function of aging mice

The aim of the present work is to study the change with aging in the effect in vitro of several antioxidants: thiazolidine-4-carboxylic acid or thioproline, N-acetylcysteine (NAC), ascorbic acid (AA), and alpha-tocopherol (vitamin E, VE) on the natural killer (NK) activity in mononuclear cells from axillary nodes, spleen, thymus and peritoneal leukocytes from BALB/c male mice. Young (8+/-2 weeks), adult (24+/-2 weeks). mature (48+/-2 weeks), and old (72+/-2 weeks) animals were studied. A nonradioactive cytotoxic assay with cells from the murine lymphoma YAC-1 as target cells and a relation effector cells/target cells of 10/1 were used. The concentrations of the different antioxidants were: 1 mM for thioproline and N-acetylcysteine and 5 microM for ascorbic acid and alpha-tocopherol, which induced a maximum effect in our previous dose-response experiments. The results show that, in general, the above antioxidants cause an enhancement of the NK activity at all ages studied, this stimulation being higher with thioproline and N-acetylcysteine than with ascorbic acid and alpha-tocopherol. The effects were similar for the three lymphoid organs and the peritoneum. This stimulation of the NK activity by antioxidants is an important favorable response, especially in old mice, in which age results in a decrease in NK function and, therefore, in a higher incidence of neoplasia.

Changes in several functions of murine peritoneal macrophages by N-acetylcysteine and thioproline ingestion. Comparative effect between two strains of mice

The administration of the thiol compounds, N-acetylcysteine (NAC) and in particular thioproline (thiazolidine-4-carboxylic acid) at 0.1% w/w concentration in the diet, improves lymphocyte functions in old female Swiss mice, as has been shown in our previous studies. In the present work, adult mice from two different strains, namely BALB/c (an inbred strain) and OF1-Swiss (noninbred strain), were fed a diet supplemented with the above dose of each thiol compound jointly for five weeks. At 28 weeks of age, peritoneal cell suspensions were obtained and different steps of the phagocytic process, the most representative activity of macrophages, as well as interleukin-1beta (IL-1beta) production, were studied. Thus, adherence to substrate, mobility directed to a chemoattractant gradient (chemotaxis), ingestion of inert particles and superoxide anion production were analysed. The results show that diet supplementation with NAC plus thioproline increased all macrophage functions studied with the exception of superoxide anion production, which was decreased. These effects were more evident in macrophages from Swiss mice, whereas in BALB/c mice the stimulation of phagocytosis and IL-1beta production was lower and no differences were seen after treatment in adherence and superoxide anion production. These data suggest that immune function can be improved in adult mice by administration of the above thiol compounds, especially in the noninbred strain of OF1-Swiss mice.