Simultaneous recording of calcium transients and reactive oxygen intermediates of human polymorphonuclear granulocytes in response to formyl-Met-Leu-Phe and the environmental agent sulfite

Physiological roles of hydrogen sulfide in mammalian cells, tissues and organs

H2S belongs to the class of molecules known as gasotransmitters, which also includes nitric oxide (NO) and carbon monoxide (CO). Three enzymes are recognized as endogenous sources of H2S in various cells and tissues: cystathionine g-lyase (CSE), cystathionine β-synthase (CBS) and 3-mercaptopyruvate sulfurtransferase (3-MST). The current article reviews the regulation of these enzymes as well as the pathways of their enzymatic and non-enzymatic degradation and elimination. The multiple interactions of H2S with other labile endogenous molecules (e.g. NO) and reactive oxygen species are also outlined. The various biological targets and signaling pathways are discussed, with special reference to H2S and oxidative posttranscriptional modification of proteins, the effect of H2S on channels and intracellular second messenger pathways, the regulation of gene transcription and translation and the regulation of cellular bioenergetics and metabolism. The pharmacological and molecular tools currently available to study H2S physiology are also reviewed, including their utility and limitations. In subsequent sections, the role of H2S in the regulation of various physiological and cellular functions is reviewed. The physiological role of H2S in various cell types and organ systems are overviewed. Finally, the role of H2S in the regulation of various organ functions is discussed as well as the characteristic bell-shaped biphasic effects of H2S. In addition, key pathophysiological aspects, debated areas, and future research and translational areas are identified A wide array of significant roles of H2S in the physiological regulation of all organ functions emerges from this review.

Exogenous sulphide donors modify the gene expression patterns of Atlantic salmon nasal leukocytes

Hydrogen sulphide (H₂S) is a known mediator of immunity, but the regulatory function of its exogenous form is not well understood in fish particularly in the mucosa. Here we report transcriptomic changes in the nasal leukocytes of Atlantic salmon (Salmo salar) following exposure to two forms of H₂S donors - the salt sodium hydrosulfide (NaHS) and the organic analogue morpholin-4-ium 4-methoxyphenyl (morpholino) phosphinodithioate (GYY4137). Nasal leukocytes were exposed to three concentrations (1, 10 and 100 μM) of either of the two H₂S forms for 24 h before the cells were checked for viability and collected for microarray analysis. Though cellular viability was minimally affected by the exposure to two H₂S donors, GYY4137-exposed cells exhibited reduced viability compared with the NaHS group at the highest dose. The H₂S-induced transcriptomic changes in the nasal leukocytes were concentration-dependent regardless of the sulphide forms. However, a larger number of differentially expressed genes (DEGs) were identified in the NaHS-exposed versus GYY4137-exposed groups across concentrations. In all comparisons, at least 53% of the DEGs identified were significantly upregulated. Gene ontology (GO) terms enriched in the lists of upregulated DEGs at higher concentrations included ferric iron binding. A comparison of the two H₂S forms showed a clear grouping of different GO terms relative to concentrations. Pathway enrichment analysis revealed a significant influence in VEGF ligand-receptor interactions, oxidative stress, innate and adaptive immunity, and interleukin signalling especially at higher concentrations. Congruence analysis demonstrated that there were 16 GO terms overlapping; of these, 12 were upregulated by both sulphide donors including several involving iron binding and transport. The study offers the first molecular insights into how fish nasal leukocytes respond to exogenous H₂S, and the results will be vital in resolving the regulatory function of H₂S on mucosal immunity in fish.

Hydrogen sulfide: An endogenous regulator of the immune system

Hydrogen sulfide (H₂S) is now recognized as an endogenous signaling gasotransmitter in mammals. It is produced by mammalian cells and tissues by various enzymes - predominantly cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE) and 3-mercaptopyruvate sulfurtransferase (3-MST) - but part of the H₂S is produced by the intestinal microbiota (colonic H₂S-producing bacteria). Here we summarize the available information on the production and functional role of H₂S in the various cell types typically associated with innate immunity (neutrophils, macrophages, dendritic cells, natural killer cells, mast cells, basophils, eosinophils) and adaptive immunity (T and B lymphocytes) under normal conditions and as it relates to the development of various inflammatory and immune diseases. Special attention is paid to the physiological and the pathophysiological aspects of the oral cavity and the colon, where the immune cells and the parenchymal cells are exposed to a special "H₂S environment" due to bacterial H₂S production. H₂S has many cellular and molecular targets. Immune cells are "surrounded" by a "cloud" of H₂S, as a result of endogenous H₂S production and exogenous production from the surrounding parenchymal cells, which, in turn, importantly regulates their viability and function. Downregulation of endogenous H₂S producing enzymes in various diseases, or genetic defects in H₂S biosynthetic enzyme systems either lead to the development of spontaneous autoimmune disease or accelerate the onset and worsen the severity of various immune-mediated diseases (e.g. autoimmune rheumatoid arthritis or asthma). Low, regulated amounts of H₂S, when therapeutically delivered by small molecule donors, improve the function of various immune cells, and protect them against dysfunction induced by various noxious stimuli (e.g. reactive oxygen species or oxidized LDL). These effects of H₂S contribute to the maintenance of immune functions, can stimulate antimicrobial defenses and can exert anti-inflammatory therapeutic effects in various diseases.

Dinucleoside polyphosphates: newly detected uraemic compounds with an impact on leucocyte oxidative burst

BACKGROUND

Dinucleoside polyphosphates (Np(n)N) have pathophysiologic roles in cardiovascular disease and are newly detected uraemic retention solutes. They were retrieved in human plasma, tissues and cells. Although their impact on several cell systems involved in vascular damage (endothelium, smooth muscle cells and thrombocytes) has been evaluated, their effect on different types of leucocytes has never been studied.

METHODS

This study evaluates, for the first time, the impact of Np(n)N on monocyte, granulocyte and lymphocyte oxidative burst activity at baseline and after stimulation with N-formyl-methionine-leucine-phenylalanine (fMLP) and phorbol 12-myristate 13-acetate (PMA) in whole blood. Diadenosine triphosphate (Ap(3)A) to diadenosine hexaphosphate (Ap(6)A) were tested to investigate the effect of the number of phosphate groups on reactive oxygen species (ROS) production. The effect of the type of nucleoside was evaluated by comparing adenosine guanosine tetraphosphate, diguanosine tetraphosphate, uridine adenosine tetraphosphate (Up(4)A) and diadenosine tetraphosphate (Ap(4)A).

RESULTS

This study demonstrated that lymphocytes are especially susceptible to intracellular diadenosine polyphosphates. Depending on the phosphate chain length, different effects were observed. At baseline and with fMLP, Ap(4)A, Ap(5)A and Ap(6)A enhanced lymphocyted-free radical production. In addition, Ap(3)A, Ap(4)A and Ap(5)A increased PMA-stimulated ROS production in lymphocytes. Monocytes and granulocytes parallel the lymphocyte response albeit with an inhibition of Ap(6)A on granulocytes. Considering Np(n)N with four phosphate groups, Up(4)A showed the most important stimulatory effects on monocytes and Ap(4)A on lymphocytes.

CONCLUSIONS

Np(n)N mainly have a leucocyte-activating impact, most significant for Ap(4)A, considering phosphate chain length, and for Up(4)A, considering the type of nucleosides. These results suggest that the pro-inflammatory effects of Np(n)N can contribute to the development of atherosclerosis, probably in the early stages of chronic kidney disease, but their chemical composition affects their activity.

Flow cytometric calcium flux assay: evaluation of cytoplasmic calcium kinetics in whole blood leukocytes

In leukocytes, as in many other cell types, cytoplasmic calcium ([Ca(2+)](i)) changes play a key role in a series of pathways leading to activation. Here we describe a flow cytometric method allowing the simultaneous kinetic analysis of changes in [Ca(2+)](i) in the three types of leukocytes, i.e. monocytes, granulocytes and lymphocytes. Heparinised whole blood was diluted in phosphate buffered saline with Ca(2+) and 1 mM sodium pyruvate and incubated with the Ca(2+) indicator fluo3-acetoxymethyl ester. Leukocytes were identified by labelling with the phycoerythrin-conjugated antibody against CD45, the leukocyte common antigen. Resuspension of the cells in PBS with or without Ca(2+) allowed us to detect the origin of Ca(2+) changes. During flow cytometric analysis only CD45-positive cells were counted and monocytes, granulocytes and lymphocytes were evaluated separately. Baseline fluorescence of the fluo3-Ca(2+)-complex was determined and changes in [Ca(2+)](i) after stimulation with the calcium ionophore A23187 or the chemotactic peptide N-formyl-methionyl-leucyl-phenylalanine (fMLP) were recorded over a time period of 150 s. Stimulation with A23187 resulted in a rise in [Ca(2+)](i) in all three leukocyte subpopulations. This rise was sustained in the presence of extracellular Ca(2+) (Ca(2+)(ex)) but had a transient character in the absence of Ca(2+)(ex). For fMLP, [Ca(2+)](i) changes occurred only in monocytes and granulocytes and were transient irrespective of the presence or absence of Ca(2+)(ex). In conclusion, the present method is a simple, fast and easy tool to analyse in vitro [Ca(2+)](i) changes over time in leukocytes under physiologically relevant conditions, without the need for their isolation or the lysis of erythrocytes. The whole blood approach allows a continuous interaction between the different leukocyte subpopulations and other blood components and a minimum of preparative manipulations avoids artefactual activation of the cells. A distinction can be made between Ca(2+) release from the intracellular stores and the entry of Ca(2+) from outside the cell. The approach allows to evaluate the effect of various agonists on [Ca(2+)](i) changes in leukocytes, with physiological, patho-physiological or therapeutic purposes.

Ceruloplasmin, copper, selenium, iron, zinc, and manganese levels in normal and sulfite oxidase deficient rat plasma: effects of sulfite exposure

A noticeable effect of sulfite treatment was observed on the plasma ceruloplasmin ferroxidase activity of rats with normal sulfite oxidase activity when compared to normal controls. The plasma levels of selenium, iron, and zinc were unaffected by sulfite in normal and sulfite oxidase (SOX)-deficient rats. While plasma level of Mn was decreasing, plasma Cu level increased in SOX-deficient rats. Treating SOX-deficient groups with sulfite did not alter plasma level of Mn but made plasma level of Cu back to its normal level. This is the first evidence that Cu and Mn status were affected in experimental sulfite oxidase deficiency induced by low molybdenum diet with tungsten addition deserving further research to determine the underlying mechanisms of these observations in experimental sulfite oxidase deficiency.

Circulating CD10-/CD16low neutrophils provide a quantitative index of active bone marrow neutrophil release

Circulating neutrophil phenotype and function are altered during neutrophilia associated with acute inflammatory states, however, the contribution of bone marrow neutrophil release to these changes has been difficult to quantify in humans. Accelerated release of neutrophils, with potentially distinct attributes, from the bone marrow and their dilution within the circulating pool may produce these apparent changes. Unfortunately selective analysis of these newly emergent neutrophils is difficult given their morphologic similarity to those already in the circulation and the coincident effect of soluble inflammatory mediators on circulating neutrophil phenotype and function. Using whole blood flow cytometry and cardiac surgery as an inflammatory stimulus, we demonstrate the emergence of a unique subpopulation of circulating neutrophils characterised as CD10(-)/CD16(low), indicative of active bone marrow neutrophil release peri-operatively. CD10(-)/CD16(low) neutrophils emerge at the same operative stages as band forms and a left shift, yet represent over 40% of circulating neutrophils postoperatively, and generate a greater stimulus-induced [Ca(2+)](i) flux than their CD10(+) counterparts. We conclude that CD10(-)/CD16(low) neutrophils represent a significant proportion of the circulating pool after cardiac surgery and that bone marrow release, a major contributor to neutrophilia, influences the phenotype and functional activity of circulating neutrophils following this acute inflammatory stimulus.

Effect of sulfite on macrophage functions of normal and sulfite oxidase-deficient rats

Sulfite has both an endogenous and an exogenous provenance in the mammalian tissues. The aim of the present study was to assess the effect of sulfite on macrophages functions in normal or sulfite oxidase deficient rats. Rats were divided into eight groups; (1) control group, (2) sulfite group (the rats received sodium meta bi-sulfite (25 mg/kg) in drinking water for 6 weeks), (3) vitamin E group (the rats received Vit E (50 mg/kg) by gavage for 6 weeks), (4) sulfite group+Vit E, (5)sulfite oxidase deficient group (the rats received high-W/Mo-deficient diet. The activity of sulfite oxidase was reduced in rats maintained on the high-W/Mo-deficient diet during the first 21 days of treatment. After the sulfite-oxidase deficiency, the rats continued to receive high-W/Mo-deficient diet for 6 weeks.), (6) sulfite+sulfite oxidase deficient group, (7) Vit E+sulfite oxidase deficient group, and (8) sulfite+Vit E+sulfite oxidase deficient group. Sulfite caused a significant increase in phagocytic and chemotactic activities of peritoneal macrophages. In sulfite-oxidase deficient rats, the increase in phagocytic and chemotactic activities in peritoneal macrophages after sulfite intake was found more than the control rats. Vit E supplementation prevented sulfite induced increase in macrophages functions. These results show that the macrophage functions are sensitive to sulfite intake. The effect of sulfite on macrophage functions may be related to reactive oxygen species. Because Vit E administration was able to modulate significantly sulfite-induced changes in the functions of peritoneal macrophages.

Quantification of temporary and permanent subpopulations of bull sperm by an optimized SYBR-14/propidium iodide assay

BACKGROUND

The quality of bull sperm is a key factor in the field of controlled reproduction. Viability-testing is an important aspect of sperm quality definition, especially after cryopreservation where multiple factors such as handling, freeze-thaw cycle, and preservation media, have an impact on the metabolic and functional state of sperm cells.

METHODS

We investigated the commonly used SYBR-14/propidium iodide (PI) assay to obtain functional information about sperm-dye and dye-dye interactions. After optimizing filter settings, dye concentrations and incubation times we used these dyes for an interruption free flow cytometric kinetic analysis of a mixture of viable and dead bovine sperm.

RESULTS

For the sensitivity of this method and the separation of the different cellular subpopulations fluorescence quenching of SYBR-14 by PI is mainly responsible. Together with a spectral overlap of the two emission spectra of about 5%, even for a wavelength greater than 700 nm, this quenching effect has to be taken into account for a quantitative understanding of the observed fluorescence intensity signals. The fraction of a temporary "intermediate" population to be observed between the viable and dead cells in an SYBR-14/PI-dot-plot diagram becomes greater after stress on the sperm cells caused by cryopreservation. The temporary fraction of "intermediate" cells is maximal at about 6 min after staining and disappears after about 15 min by shifting towards the dead sperm population. The estimation of this "intermediate" population may be a good indicator for handling and storage induced detrimental effects on bovine sperm cells.

CONCLUSION

The SYBR-14/PI assay is a fast, reliable and sensitive method to assess the membrane integrity of bull sperm and to separate viable, dead, and "intermediate" sperm subpopulations.