Respiratory burst function of ovine neutrophils

Lung Microbiome as a Treatable Trait in Chronic Respiratory Disorders

Once thought to be a sterile environment, it is now established that lungs are populated by various microorganisms that participate in maintaining lung function and play an important role in shaping lung immune surveillance. Although our comprehension of the molecular and metabolic interactions between microbes and lung cells is still in its infancy, any event causing a persistent qualitative or quantitative variation in the composition of lung microbiome, termed "dysbiosis", has been virtually associated with many respiratory diseases. A deep understanding of the composition and function of the "healthy" lung microbiota and how dysbiosis can cause or participate in disease progression will be pivotal in finding specific therapies aimed at preventing diseases and restoring lung function. Here, we review lung microbiome dysbiosis in different lung pathologies and the mechanisms by which these bacteria can cause or contribute to the severity of the disease. Furthermore, we describe how different respiratory disorders can be caused by the same pathogen, and that the real pathogenetic mechanism is not only dependent by the presence and amount of the main pathogen but can be shaped by the interaction it can build with other bacteria, fungi, and viruses present in the lung. Understanding the nature of this bacteria crosstalk could further our understanding of each respiratory disease leading to the development of new therapeutic strategies.

A review of chemical warfare agents linked to respiratory and neurological effects experienced in Gulf War Illness

Over 40% of veterans from the Persian Gulf War (GW) (1990-1991) suffer from Gulf War Illness (GWI). Thirty years since the GW, the exposure and mechanism contributing to GWI remain unclear. One possible exposure that has been attributed to GWI are chemical warfare agents (CWAs). While there are treatments for isolated symptoms of GWI, the number of respiratory and cognitive/neurological issues continues to rise with minimum treatment options. This issue does not only affect veterans of the GW, importantly these chronic multisymptom illnesses (CMIs) are also growing amongst veterans who have served in the Afghanistan-Iraq war. What both wars have in common are their regions and inhaled exposures. In this review, we will describe the CWA exposures, such as sarin, cyclosarin, and mustard gas in both wars and discuss the various respiratory and neurocognitive issues experienced by veterans. We will bridge the respiratory and neurological symptoms experienced to the various potential mechanisms described for each CWA provided with the most up-to-date models and hypotheses.

Effect of hydrogen peroxide on the oxidative burst of neutrophils in pigs and ruminants

Background and Aim

Neutrophils represent between 20% and 75% of white blood cells in animals and play a key role in an effective immune response. The generation of reactive oxygen species (ROS) is commonly referred to as an oxidative burst and is crucial under healthy and disease conditions. Interestingly, ROS are emerging as regulators of several neutrophil functions, including their oxidative burst. The present study aimed to investigate the effect of hydrogen peroxide on the oxidative burst of neutrophils, collected from domestic animal species (namely, pig, cattle, and sheep), and exposed to different stimuli.

Materials and Methods

A total of 65 slaughtered animals were included in the present study: Twenty-two pigs, 21 cattle, and 22 sheep. Blood samples were collected at bleeding and neutrophils were then purified using ad hoc developed and species-specific protocols. Neutrophils were treated with hydrogen peroxide at micromolar-to-millimolar concentrations, alone, or combined with other stimuli (i.e., opsonized yeasts, and phorbol 12-myristate 13-acetate). The generation of ROS was evaluated using a luminol-derived chemiluminescence (CL) assay. For each animal species, data were aggregated and reported as mean area under curve±standard deviation. Finally, data were statistically analyzed by one-way ANOVA, followed by Tukey's post hoc test.

Results

Exposure of bovine and ovine neutrophils to hydrogen peroxide alone resulted in a dose-dependent enhancement of the CL response, which was significantly stronger at its highest concentration and proved particularly prominent in sheep. Opsonized yeasts and phorbol 12-myristate 13-acetate both proved capable of stimulating the generation of ROS in all animal species under study. Hydrogen peroxide negatively modulated the oxidative burst of neutrophils after exposure to those stimuli, observed response patterns varying between pigs and ruminants. Porcine neutrophils, pre-exposed to micromolar concentrations of hydrogen peroxide, showed a decreased CL response only to opsonized yeasts. Conversely, pre-exposure to hydrogen peroxide reduced the CL response of ruminant neutrophils both to yeasts and phorbol 12-myristate 13-acetate, the effect being most prominent at 1 mM concentration.

Conclusion

These results indicate that hydrogen peroxide is capable of modulating the oxidative bursts of neutrophils in a species-specific and dose-dependent manner, substantial differences existing between pigs and ruminants. Further investigation is required to fully comprehend such modulation, which is crucial for the proper management of the generation of ROS under healthy and disease conditions.

What Is the Evolutionary Fingerprint in Neutrophil Granulocytes?

Over the years of evolution, thousands of different animal species have evolved. All these species require an immune system to defend themselves against invading pathogens. Nevertheless, the immune systems of different species are obviously counteracting against the same pathogen with different efficiency. Therefore, the question arises if the process that was leading to the clades of vertebrates in the animal kingdom-namely mammals, birds, amphibians, reptiles, and fish-was also leading to different functions of immune cells. One cell type of the innate immune system that is transmigrating as first line of defense in infected tissue and counteracts against pathogens is the neutrophil granulocyte. During the host-pathogen interaction they can undergo phagocytosis, apoptosis, degranulation, and form neutrophil extracellular traps (NETs). In this review, we summarize a wide spectrum of information about neutrophils in humans and animals, with a focus on vertebrates. Special attention is kept on the development, morphology, composition, and functions of these cells, but also on dysfunctions and options for cell culture or storage.

Sevoflurane modulates the release of reactive oxygen species, myeloperoxidase, and elastase in human whole blood: Effects of different stimuli on neutrophil response to volatile anesthetic in vitro

Volatile anesthetics have been shown to modulate polymorphonuclear neutrophil (PMN) functions. The aim of this study was to examine the impact of clinically relevant concentrations of sevoflurane (SEVO), a volatile anesthetic, on the release of reactive oxygen species (ROS), myeloperoxidase (MPO), and elastase (EL) from human activated PMNs. For this purpose, samples of whole blood were collected from healthy volunteers and exposed in vitro to 2.3% or 4.6% SEVO in air. To assess for a stimulus-dependent effect of the volatile anesthetic, PMNs were activated using different validated protocols. Artificial stimulation of neutrophils involved either a combination of cytochalasin B (CB) and N-formyl-methionyl-leucyl-phenylalanine (fMLP) or phorbol 12-myristate 13-acetate (PMA). In addition, a combination of lipopolysaccharide (LPS) and tumor necrosis factor alpha (TNF-α) was also tested as a natural activation mean of PMNs. The production of ROS by PMNs was assessed by L-012 chemiluminescence. Total MPO and EL released in supernatant were measured by enzyme-linked immunosorbent assay (ELISA). Furthermore, degranulation of the active fraction of MPO was also measured by specific immunological extraction followed by enzymatic detection (SIEFED). Overall, SEVO enhanced the release of ROS, MPO, and EL following artificial stimulation of PMNs but the volatile anesthetic inhibited the degranulation of active MPO and EL after neutrophil exposure to LPS and TNF-α. This study highlighted that the effect of SEVO on activated PMNs is dependent on the conditions of cell stimulation. These properties should be taken into consideration in future studies investigating immunomodulatory effects of volatile anesthetics.

The GRIM-19 plays a vital role in shrimps' responses to Vibrio alginolyticus

GRIM-19 (gene associated with retinoid-interferon-induced mortality 19), a novel cell death regulatory gene, plays important roles in cell apoptosis, mitochondrial respiratory chain and immune response. It has been reported to interact physically with STAT3 and inhibit STAT3-dependent signal transduction. In this study, a new GRIM-19 gene, which is a 789-bp gene encoding a 149 amino acids protein, is identified and characterized from Litopenaeus vannamei. The tissue distribution patterns showed that LvGRIM-19 was widely expressed in all examined tissues, with the highest expression in muscle. Quantitative real-time PCR revealed that LvGRIM-19 was down-regulated in hepatopancreas after infection with the Vibrio alginolyticus. Knockdown of LvGRIM-19 by RNA interference resulted in a lower mortality of L. vannamei under V. alginolyticus infection, as well as an enhancement in the protein expression of STAT gene and JAK gene. V. alginolyticus infection caused an increase apoptotic cell ratio and ROS production of L. vannamei, while LvGRIM-19 silenced shrimps showed significantly lower than GFP group. Our results suggest that the GRIM-19 plays a vital role in shrimps' responses to V. alginolyticus. Interferenced LvGRIM-19 treatment during V. alginolyticus infection could increase 12 h survival rate, which might indicated that LvGRIM-19 is closely related to death of shrimps.

Novel 24-h ovine model of brain death to study the profile of the endothelin axis during cardiopulmonary injury

BACKGROUND

Upregulation of the endothelin axis has been observed in pulmonary tissue after brain death, contributing to primary graft dysfunction and ischaemia reperfusion injury. The current study aimed to develop a novel, 24-h, clinically relevant, ovine model of brain death to investigate the profile of the endothelin axis during brain death-associated cardiopulmonary injury. We hypothesised that brain death in sheep would also result in demonstrable injury to other transplantable organs.

METHODS

Twelve merino cross ewes were randomised into two groups. Following induction of general anaesthesia and placement of invasive monitoring, brain death was induced in six animals by inflation of an extradural catheter. All animals were supported in an intensive care unit environment for 24 h. Animal management reflected current human donor management, including administration of vasopressors, inotropes and hormone resuscitation therapy. Activation of the endothelin axis and transplantable organ injury were assessed using ELISA, immunohistochemistry and standard biochemical markers.

RESULTS

All animals were successfully supported for 24 h. ELISA suggested early endothelin-1 and big endothelin-1 release, peaking 1 and 6 h after BD, respectively, but there was no difference at 24 h. Immunohistochemistry confirmed the presence of the endothelin axis in pulmonary tissue. Brain dead animals demonstrated tachycardia and hypertension, followed by haemodynamic collapse, typified by a reduction in systemic vascular resistance to 46 ± 1 % of baseline. Mean pulmonary artery pressure rose to 186 ± 20 % of baseline at induction and remained elevated throughout the protocol, reaching 25 ± 2.2 mmHg at 24 h. Right ventricular stroke work increased 25.9 % above baseline by 24 h. Systemic markers of cardiac and hepatocellular injury were significantly elevated, with no evidence of renal dysfunction.

CONCLUSIONS

This novel, clinically relevant, ovine model of brain death demonstrated that increased pulmonary artery pressures are observed after brain death. This may contribute to right ventricular dysfunction and pulmonary injury. The development of this model will allow for further investigation of therapeutic strategies to minimise the deleterious effects of brain death on potentially transplantable organs.

Optimal management of the critically ill: anaesthesia, monitoring, data capture, and point-of-care technological practices in ovine models of critical care

Animal models of critical illness are vital in biomedical research. They provide possibilities for the investigation of pathophysiological processes that may not otherwise be possible in humans. In order to be clinically applicable, the model should simulate the critical care situation realistically, including anaesthesia, monitoring, sampling, utilising appropriate personnel skill mix, and therapeutic interventions. There are limited data documenting the constitution of ideal technologically advanced large animal critical care practices and all the processes of the animal model. In this paper, we describe the procedure of animal preparation, anaesthesia induction and maintenance, physiologic monitoring, data capture, point-of-care technology, and animal aftercare that has been successfully used to study several novel ovine models of critical illness. The relevant investigations are on respiratory failure due to smoke inhalation, transfusion related acute lung injury, endotoxin-induced proteogenomic alterations, haemorrhagic shock, septic shock, brain death, cerebral microcirculation, and artificial heart studies. We have demonstrated the functionality of monitoring practices during anaesthesia required to provide a platform for undertaking systematic investigations in complex ovine models of critical illness.

TAT-SNAP-23 treatment inhibits the priming of neutrophil functions contributing to shock and/or sepsis-induced extra-pulmonary acute lung injury

Respiratory burst function of neutrophils is thought to play a pivotal role in the development of pathologies such as indirect (extra-pulmonary) acute lung injury (iALI), as well as sepsis. The current study was conducted to determine the effect of an HIV transactivator of transcription (TAT)-fusion protein containing a soluble N-ethylmaleimide-sensitive factor attachment protein receptor domain from synaptosome-associated protein-23 (SNAP-23) on the shock/sepsis- and sepsis-enhanced neutrophil burst capacity using the clinical relevant two-hit iALI mouse model and the classical cecal ligation and puncture (CLP) septic model. TAT-SNAP-23 significantly decreased the blood neutrophil respiratory burst in vitro, and also in vivo in CLP and hemorrhaged mice. We found that the neutrophil influx to the lung tissue, as measured by myeloperoxidase levels and neutrophil-specific esterase(+) cells, was also decreased in the TAT-SNAP-23-treated group. Consistent with this, treatment of TAT-SNAP-23 significantly reduced the disruption of lung tissue architecture and protein concentration of bronchoalveolar lavage fluid in iALI mice compared with vehicle-treated iALI mice. In addition, although TAT-SNAP-23 did not alter the extent of local cytokine/chemokine expression, the in vitro migration capacity of neutrophils was blunted from septic and hemorrhagic mice. These data support our hypothesis that TAT-SNAP-23 reduces neutrophil dysfunction in iALI and sepsis by inhibiting neutrophil respiratory burst.

Design and synthesis of tryptophan containing dipeptide derivatives as formyl peptide receptor 1 antagonist

Our previous studies identified an Fmoc-(S,R)-tryptophan-containing dipeptide derivative, 1, which selectively inhibited neutrophil elastase release induced by formyl-L-methionyl-L-leucyl-L-phenylalanine (FMLP) in human neutrophils. In an attempt to improve pharmacological activity, a series of tryptophan-containing dipeptides were synthesized and their pharmacological activities were investigated in human neutrophils. Of these, five compounds 3, 6, 19a, 24a, and 24b exhibited potent and dual inhibitory effects on FMLP-induced superoxide anion (O2˙(-)) generation and neutrophil elastase release in neutrophils with IC50 values of 0.23/0.60, 1.88/2.47, 1.87/3.60, 0.12/0.37, and 1.32/1.03 μM, respectively. Further studies indicated that inhibition of superoxide production in human neutrophils by these dipeptides was associated with the selective inhibition of formyl peptide receptor 1 (FPR1). Furthermore, the results of structure-activity relationship studies concluded that the fragment N-benzoyl-Trp-Phe-OMe (3) was most suitable as a core structure for interaction with FPR1, and may be approved as a lead for the development of new drugs in the treatment of neutrophilic inflammatory diseases. As some of the synthesized compounds exhibited separable conformational isomers, and showed diverse bioactivities, the conformation analysis of these compounds is also discussed herein.

Coefficient of energy balance: effective tool for early differential diagnosis of CNS diseases

Urgent examination of cerebrospinal fluid (CSF) provides immediate important information about the character of central nervous system (CNS) impairment. Although this examination includes energy parameters such as glucose and lactate concentrations, it does not commonly use Coefficient of Energy Balance (CEB). In this study, we focused on CEB because it enables more exact assessment of actual energy state in the CSF compartment than glucose and lactate alone. CEB informs about the actual functioning condition of present cells, and it does not require any other analysis or costs. Using Kruskal-Wallis ANOVA, we examined a large CSF sample (n = 8183) and we compared CEB values among groups with different cytological syndromes. We found a statistically significant difference of CEB between the group with granulocyte pleocytosis and the control group. These results indicate a high degree of anaerobic metabolism caused by the oxidative burst of neutrophils. Similarly, we found a statistically significant difference of CEB between the control group and groups with tumorous oligocytosis plus pleocytosis and monocyte pleocytosis. This difference can be attributed to the oxidative burst of macrophages. Our findings suggest that CEB combined with CSF cytology has a great importance for diagnosis, differential diagnosis, and early therapy of CNS diseases.

Is hyperoxaemia helping or hurting patients during extracorporeal membrane oxygenation? Review of a complex problem

Extracorporeal membrane oxygenation (ECMO) facilitates organ support in patients with refractory cardiorespiratory failure whilst disease-modifying treatments can be administered. Improvements to the ECMO process have resulted in its increased utilisation. However, iatrogenic injuries remain, with bleeding and thrombosis the most significant concerns. Many factors contribute to the formation of thrombi, with the hyperoxaemia experienced during ECMO a potential contributor. Outside of ECMO, emerging evidence associates hyperoxaemia with increased mortality. Currently, no universal definition of hyperoxaemia exists, a gap in clinical standards that may impact patient outcomes. Hyperoxaemia has the potential to induce platelet activation, aggregation and, subsequently, thrombosis through markedly increasing the production of reactive oxygen species. There are minimal data in the current literature that explore the relationship between ECMO-induced hyperoxaemia and the production of reactive oxygen species – a putative link towards pathology. Furthermore, there is limited research directly linking hyperoxaemia and platelet activation. These are areas that warrant investigation as definitive data regarding the nascence of these pathological processes may delineate and define the relative risk of supranormal oxygen tension. These data could then assist in defining optimal oxygenation practice, reducing the risks associated with extracorporeal support.

A novel in vivo ovine model of transfusion-related acute lung injury (TRALI)

BACKGROUND AND OBJECTIVES

Even with the introduction of specific risk-reduction strategies, transfusion-related acute lung injury (TRALI) continues to be a leading cause of transfusion-related morbidity and mortality. Existing small animal models have not yet investigated TRALI resulting from the infusion of heat-treated supernatant from whole blood platelet concentrates. In this study, our objective was the development of a novel in vivo two-event model of TRALI in sheep.

MATERIALS AND METHODS

Lipopolysaccharide (LPS; 15 μg/kg) as a first event, modelled clinical infection. Transfusion (estimated at 10% of total blood volume) of heat-treated pooled supernatant from date-of-expire human whole blood platelet concentrates (d5-PLT-S/N) was used as a second event. TRALI was defined by both hypoxaemia that developed either during the transfusion or within two hours of its completion and post-mortem histological evidence of pulmonary oedema.

RESULTS

LPS infusion did not cause lung injury itself, but did result in decreased circulating levels of lymphocytes and neutrophils with evidence of the latter becoming sequestered in the lungs. Sheep that received LPS (first event) followed by d5-PLT-S/N (second event) displayed decreased pulmonary compliance, decreased end tidal CO(2) and increased arterial partial pressure of CO(2) relative to control sheep, and 80% of these sheep developed TRALI.

CONCLUSIONS

This novel ovine two-event TRALI model presents a new tool for the investigation of TRALI pathogenesis. It represents the first description of an in vivo large animal model of TRALI and the first description of TRALI caused by transfusion with heat-treated pooled supernatant from human whole blood platelet concentrates.