NAADP: From Discovery to Mechanism.

Nicotinic acid adenine dinucleotide 2'-phosphate (NAADP) is a naturally occurring nucleotide that has been shown to be involved in the release of Ca2+ from intracellular stores in a wide variety of cell types, tissues and organisms. Current evidence suggests that NAADP may function as a trigger to initiate a Ca2+ signal that is then amplified by other Ca2+ release mechanisms. A fundamental question that remains unanswered is the identity of the NAADP receptor. Our recent studies have identified HN1L/JPT2 as a high affinity NAADP binding protein that is essential for the modulation of Ca2+ channels.

Impaired host defence against Mycobacterium avium in mice with chronic granulomatous disease.

Patients with chronic granulomatous disease (CGD), an inherited disorder of phagocytic cells, often contract recurrent life-threatening bacterial and fungal infections. CGD is considered to arise from a functional defect of the O(2)-generating nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in phagocytes. To determine whether or not NADPH oxidase is crucial to the host defence against Mycobacterium avium, we investigated the response against M. avium using CGD model mice (gp91-phox(-)) of C57BL/6 strain. A tracheal injection of 1 x 10(7) colony-forming units (CFU)/head of M. avium strain FN into the CGD mice resulted in a pulmonary infection, while also increasing the mortality rate. In contrast, normal C57BL/6 mice injected with same dose of the organisms did not develop severe pulmonary infection and were able to survive through 2 months of observation. The macrophages obtained from the CGD mice were observed to have a higher burden of the bacterial growth than macrophages from normal C57BL/6 mice. These results suggest that the defect of the NADPH oxidase function impairs the host defence against M. avium infection.

Redox warfare between airway epithelial cells and Pseudomonas: dual oxidase versus pyocyanin.

The importance of reactive oxygen species-dependent microbial killing by the phagocytic cell NADPH oxidase has been appreciated for some time, although only recently has an appreciation developed for the partnership of lactoperoxidase with related dual oxidases (Duox) within secretions of the airway surface layer. This system produces mild oxidants designed for extracellular killing that are effective against several airway pathogens, including Staphylococcus aureus, Burkholderia cepacia, and Pseudomonas aeruginosa. Establishment of chronic pseudomonas infections involves adaptations to resist oxidant-dependent killing by expression of a redox-active virulence factor, pyocyanin, that competitively inhibits epithelial Duox activity by consuming intracellular NADPH and producing superoxide, thereby inflicting oxidative stress on the host.

A Pck1-directed glycogen metabolic program regulates formation and maintenance of memory CD8+ T cells.

CD8+ memory T (Tm) cells are fundamental for protective immunity against infections and cancers 1-5 . Metabolic activities are crucial in controlling memory T-cell homeostasis, but mechanisms linking metabolic signals to memory formation and survival remain elusive. Here we show that CD8+ Tm cells markedly upregulate cytosolic phosphoenolpyruvate carboxykinase (Pck1), the hub molecule regulating glycolysis, tricarboxylic acid cycle and gluconeogenesis, to increase glycogenesis via gluconeogenesis. The resultant glycogen is then channelled to glycogenolysis to generate glucose-6-phosphate and the subsequent pentose phosphate pathway (PPP) that generates abundant NADPH, ensuring high levels of reduced glutathione in Tm cells. Abrogation of Pck1-glycogen-PPP decreases GSH/GSSG ratios and increases levels of reactive oxygen species (ROS), leading to impairment of CD8+ Tm formation and maintenance. Importantly, this metabolic regulatory mechanism could be readily translated into more efficient T-cell immunotherapy in mouse tumour models.

Antioxidant Protection of NADPH-Depleted Oligodendrocyte Precursor Cells Is Dependent on Supply of Reduced Glutathione.

The pentose phosphate pathway is the main source of NADPH, which by reducing oxidized glutathione, contributes to antioxidant defenses. Although oxidative stress plays a major role in white matter injury, significance of NADPH for oligodendrocyte survival has not been yet investigated. It is reported here that the NADPH antimetabolite 6-amino-NADP (6AN) was cytotoxic to cultured adult rat spinal cord oligodendrocyte precursor cells (OPCs) as well as OPC-derived oligodendrocytes. The 6AN-induced necrosis was preceded by increased production of superoxide, NADPH depletion, and lower supply of reduced glutathione. Moreover, survival of NADPH-depleted OPCs was improved by the antioxidant drug trolox. Such cells were also protected by physiological concentrations of the neurosteroid dehydroepiandrosterone (10(-8) M). The protection by dehydroepiandrosterone was associated with restoration of reduced glutathione, but not NADPH, and was sensitive to inhibition of glutathione synthesis. A similar protective mechanism was engaged by the cAMP activator forskolin or the G protein-coupled estrogen receptor (GPER/GPR30) ligand G1. Finally, treatment with the glutathione precursor N-acetyl cysteine reduced cytotoxicity of 6AN. Taken together, NADPH is critical for survival of OPCs by supporting their antioxidant defenses. Consequently, injury-associated inhibition of the pentose phosphate pathway may be detrimental for the myelination or remyelination potential of the white matter. Conversely, steroid hormones and cAMP activators may promote survival of NADPH-deprived OPCs by increasing a NADPH-independent supply of reduced glutathione. Therefore, maintenance of glutathione homeostasis appears as a critical effector mechanism for OPC protection against NADPH depletion and preservation of the regenerative potential of the injured white matter.

Nucleotide cofactor-binding-domain-specific antibodies show immunologic relatedness among unrelated proteins that bind phosphoryl compounds.

The immunologic relatedness of various cofactor-binding sites of enzymes requiring different nucleotide cofactors was examined. Chicken antibodies specific for NADPH- or CoA-binding domains were raised using an NADPH- or CoA-requiring enzyme as an immunogen. Antibodies specific for either NADPH- or CoA-binding domains were isolated by immunoaffinity chromatography of the respective antisera using unrelated NADPH- or CoA-requiring enzymes as affinity ligands. The reactivities of the NADPH- and CoA-binding-site-specific antibodies with a variety of enzymes that required different cofactors was shown on Western blots of SDS-PAGE of the enzymes. Variable cross-reactivities were observed among all nucleotide-cofactor requiring enzymes with each specific cofactor-domain-antibody population. Numerous proteins not physiologically associated with nucleotide cofactors, including acyl carrier protein, were completely unreactive. Proteins that bound phosphoryl compounds either as substrates or cofactors showed varying degrees of reactivity with each population of specific antibodies. These included aldolase, ribulose-1,5-bisphosphate carboxylase/oxygenase, ribonuclease A, carbonic anhydrase and triosephosphate isomerase. The immunologic cross-reactivity suggested that these proteins share a common structural feature, probably a primary structure epitope, since the proteins had been subjected to denaturing polyacrylamide gel electrophoresis. A candidate for this common structural feature is a glycine-rich sequence comprising a phosphate binding loop.

Specific cell types in cat retina express different forms of glutamic acid decarboxylase.

We studied the expression of glutamate decarboxylase (GAD), GAD65 and GAD67, in cat retina by immunocytochemistry. About 10% of GABAergic amacrine cells express only GAD65 and 30% express only GAD67. Roughly 60% contain both forms of the enzyme, but GAD67 is present only at low levels in the majority of these double-labeled amacrine cells. The staining pattern in the inner plexiform layer (IPL) for the two GAD forms was also different. GAD65 was restricted to strata 1-4, and GAD67 was apparent throughout the IPL but was strongest in strata 1 and 5. This indicates that somas, as well as their processes, are differentially stained for the two forms of GAD. Cell types expressing only GAD65 include interplexiform cells, one type of cone bipolar cell, and at least one type of serotonin-accumulating amacrine cell. Cell types expressing only GAD67 include amacrine cells synthesizing dopamine, amacrine cells synthesizing nitric oxide (NO), and amacrine cells accumulating serotonin. Cholinergic amacrine cells express a low level of both GAD forms. Our findings in the retina are consistent with previous observations in the brain that GAD65 expression is greater in terminals than in somas. In addition, in retina most neurons expressing GAD67 also contain a second neurotransmitter as well as GABA, and they tend to be larger than neurons expressing GAD65. We propose that large cells have a greater demand for GABA than small cells, and thus require the constant, relatively unmodulated level of GABA that is provided by GAD67.

Mesenteric neurons in the adult rat are responsive to ileal treatment with benzalkonium chloride.

The application of a 2 mM solution of the cationic surfactant benzalkonium chloride (BAC) to an ileal segment produced a selective and extensive myenteric denervation. The aim of the present study was to investigate whether such a selective unbalance of the enteric nervous system in the adult rat elicited any plastic response within the mesenteric nervous structures contacting it. Acetylcholinesterase (AChE) staining, beta-nicotinamide adenine dinucleotide (NADH) and beta-nicotinamide adenine dinucleotide phosphate (NADPH) diaphorase histochemistry and glyoxylic acid-induced fluorescence were performed on whole-mount preparations of myenteric plexus and mesenteric nerves. In both control and BAC-treated animals nervous elements were detected along the mesenteric nerves. Although rather similar in position, shape and size, these neurons displayed striking differences with regard to their arrangement and density per nerve. In the controls, few small aggregates of neurons could be detected; more commonly, isolated nerve cell bodies were scattered along the nerve trunks. In the BAC-treated animals, numerous spherical or spindle-shaped clusters of neurons were located along the nerves; the mean neuronal density per nerve displayed a two-five-fold increase over the control values. The observed changes within the mesenteric nerves might be involved in an attempt at reinnervation of the BAC-treated intestinal segments from extra-enteric sources.

Acupuncture decreases nitric oxide synthase expression in periaqueductal gray area of rats with streptozotocin-induced diabetes.

Acupuncture has been used as a clinical treatment in Oriental medicine for various diseases including diabetes mellitus, one of the most common metabolic disorders in humans. In the present study, the effect of acupuncture on the expressions of neuronal nitric oxide synthase (nNOS) and nitric oxide synthase (NOS) in the dorsolateral periaqueductal gray (DL-PAG) area of rats with streptozotocin (STZ)-induced diabetes was investigated via nNOS immunohistochemistry and nicotinamide adenine dinucleotide phosphate-diaphorase histochemistry. Enhanced expression of nNOS and NOS was detected in the DL-PAG of rats with STZ-induced diabetes, and acupunctural treatment at Zusanli acupoint suppressed the diabetes-induced enhancement in the expression of nNOS and NOS. The present results demonstrate that acupuncture is effective in the modulation of the expression of nNOS and NOS in the DL-PAG under diabetic conditions.

Ragweed subpollen particles of respirable size activate human dendritic cells.

Ragweed (Ambrosia artemisiifolia) pollen grains, which are generally considered too large to reach the lower respiratory tract, release subpollen particles (SPPs) of respirable size upon hydration. These SPPs contain allergenic proteins and functional NAD(P)H oxidases. In this study, we examined whether exposure to SPPs initiates the activation of human monocyte-derived dendritic cells (moDCs). We found that treatment with freshly isolated ragweed SPPs increased the intracellular levels of reactive oxygen species (ROS) in moDCs. Phagocytosis of SPPs by moDCs, as demonstrated by confocal laser-scanning microscopy, led to an up-regulation of the cell surface expression of CD40, CD80, CD86, and HLA-DQ and an increase in the production of IL-6, TNF-α, IL-8, and IL-10. Furthermore, SPP-treated moDCs had an increased capacity to stimulate the proliferation of naïve T cells. Co-culture of SPP-treated moDCs with allogeneic CD3(+) pan-T cells resulted in increased secretion of IFN-γ and IL-17 by T cells of both allergic and non-allergic subjects, but induced the production of IL-4 exclusively from the T cells of allergic individuals. Addition of exogenous NADPH further increased, while heat-inactivation or pre-treatment with diphenyleneiodonium (DPI), an inhibitor of NADPH oxidases, strongly diminished, the ability of SPPs to induce phenotypic and functional changes in moDCs, indicating that these processes were mediated, at least partly, by the intrinsic NAD(P)H oxidase activity of SPPs. Collectively, our data suggest that inhaled ragweed SPPs are fully capable of activating dendritic cells (DCs) in the airways and SPPs' NAD(P)H oxidase activity is involved in initiation of adaptive immune responses against innocuous pollen proteins.

The many roles of NOX2 NADPH oxidase-derived ROS in immunity.

Reactive oxygen species (ROS) have long been studied in the context of their direct toxic effects on cells. As a result, ROS have conventionally been thought of as a necessary nuisance to aerobic living. However, in recent years, much work has been done to examine the contribution of ROS to the field of immunity. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases were identified as one of the key sources of ROS in immune cells. The NOX2 NADPH oxidase in particular has been assigned multiple roles, functioning as a source of antimicrobial ROS, an activator of many signaling pathways, a participant in chemotaxis, an immune modulator, and a critical player in the initiation of antigen cross-presentation. Furthermore, recent studies have revealed a novel role for the NOX2 NADPH oxidase in the activation of autophagy, a cellular degradative pathway. Here, we examine these functions of NOX2 NADPH oxidase in immunity.

Chronic granulomatous disease: review of a cohort of egyptian patients

BACKGROUND: Chronic granulomatous disease (CGD) is an inherited disease that results from a defect in the phagocytic cells of the immune system. It is caused by defects in one of the major subunits of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase complex. The clinical presentations of CGD patients are heterogeneous. OBJECTIVES: This is the first report from Egypt discussing clinical and laboratory data of twenty-nine patients (from 26 families) with CGD from a single tertiary referral centre. RESULTS: There were twenty male and nine female patients. The consanguinity rate was 76% (19/25). Their age of diagnosis ranged from 2 to 168 months with a mean of 52.8 months ± 49.6 SD. The most common manifestations were abscesses in 79.3% (deep organ abscesses in 37.9% of patients), followed by pneumonia in 75.8% and gastrointestinal symptoms in 27.5%. Rare but fatal complications were also reported among patients as one patient developed haemophagocytic lymphohistiocytosis (HLH) syndrome. Although X linked-CGD universally constitutes the most common pattern of inheritance; only 6 of our patients 6/25 (24%) belonged to this group with a Stimulation Index (SI) of 1-5, and confirmed by carrier pattern of their mothers. Mothers were not available for testing in four male children. Nineteen patients (76%) had autosomal recessive patterns; ten males and nine females patients based on having abnormal SI, positive history of consanguinity and their mothers showing normal SI. CONCLUSION: Increasing the awareness of physicians about symptoms of CGD may lead to earlier diagnosis of the disease, thus enhancing proper management and better quality of life

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Chemiluminescence: comparison of whole blood with isolated polymorphonuclear leukocytes after major trauma.

INTRODUCTION: Neutrophil (PMN) mediated tissue injury is central to the development of post-traumatic ARDS/MOF. Changes in activity caused by PMN isolation may be avoided by studying respiratory burst activity using whole blood chemiluminescence (WBCL). METHODS: WBCL and PMNCL were measured in 5 normal laboratory volunteers (NLV) and 9 patients sustaining major trauma, within 2 hours of admission. Receptor mediated (STZ) and independent (PMA) activating agents were used. RESULTS: PMA activation confirmed significant priming both in WBCL and PMNCL after major trauma. With STZ, priming was confirmed in the WBCL study, but the trauma patient PMNCL showed no difference in response to those of NLV. Although the study population was small, those patients later developing ARDS demonstrated significantly greater STZ activated WBCL, 8 hours after admission. CONCLUSION: PMN isolation alters behavior in vitro. This may lead to important differences of in vivo PMN function being obscured when studied in the laboratory setting. Further study of CL response and surface receptor expression is clearly warranted, both in WB and PMN preparations.

Glucose deprivation decreases nitric oxide production via NADPH depletion in immunostimulated rat primary astrocytes.

We have previously reported that the production of nitric oxide (NO) in immunostimulated astrocytes was markedly decreased under glucose-deprived conditions. The present study was undertaken to find the contributing factor(s) for the decreased NO production in glucose-deprived immunostimulated astrocytes. NO production in rat primary astrocytes was stimulated for 24-48 h by cotreatment with lipopolysaccharides (1 microg/ml) and interferon-gamma (100 U/ml). Decreased NO production in immunostimulated astrocytes by glucose deprivation was mimicked by the glycolytic inhibitor 2-deoxyglucose and reversed by addition of pyruvate and lactate. Glucose deprivation did not alter the expression of inducible nitric oxide synthase (iNOS) in immunostimulated astrocytes. Addition of beta-NADPH, but not tetrahydrobiopterine, both of which are essential cofactors for NOS function, completely restored the NO production that was decreased in glucose-deprived immunostimulated astrocytes. Glucose deprivation and immunostimulation synergistically reduced intracellular NADPH level in astrocytes. The results indicate that glucose deprivation decreases NO production in immunostimulated astrocytes by depleting intracellular NADPH, a cofactor of iNOS.