NADPH oxidase limits innate immune responses in the lungs in mice

Gastric Aspiration and Its Role in Airway Inflammation

Gastro-Oesophageal Reflux (GOR) has been associated with chronic airway diseases while the passage of foreign matter into airways and lungs through aspiration has the potential to initiate a wide spectrum of pulmonary disorders. The clinical syndrome resulting from such aspiration will depend both on the quantity and nature of the aspirate as well as the individual host response. Aspiration of gastric fluids may cause damage to airway epithelium, not only because acidity is toxic to bronchial epithelial cells but also due to the effect of digestive enzymes such as pepsin and bile salts. Experimental models have shown that direct instillation of these factors to airways epithelia cause damage with a consequential inflammatory response. The pathophysiology of these responses is gradually being dissected, with better understanding of acute gastric aspiration injury, a major cause of acute lung injury, providing opportunities for therapeutic intervention and potentially, ultimately, improved understanding of the chronic airway response to aspiration. Ultimately, clarification of the inflammatory pathways which are related to micro-aspiration via pepsin and bile acid salts may eventually progress to pharmacological intervention and surgical studies to assess the clinical benefits of such therapies in driving symptom improvement or reducing disease progression.

Myeloid-derived suppressor cells in ovarian cancer: friend or foe?

Although previous decades contributed to major progress in targeted therapy of many malignancies, the treatment of gynaecological cancers remains a challenging task. In the evidence of rising cancer mortality, the search for new methods of treatment is a dire need. Exploring the mechanisms of interaction between tumour cells and host immune response may allow the introduction of new, effective therapies – not as toxic and far more efficient than conventional methods of cancer treatment. Epithelial ovarian cancer (EOC) is typically diagnosed at advanced stages. Its incidence and mortality rate is high. Powerful diagnostic tools for this kind of cancer are still under investigation. Multiple mechanisms existing in the ovarian tumour network create a specific immunosuppressive microenvironment, in which accumulation of myeloid-derived suppressor cells (MDSCs) may be a critical component for diagnosis and treatment. This review attempts to verify current knowledge on the role of MDSCs in EOC.

Signaling at the Crossroads: Matrix-Derived Proteoglycan and Reactive Oxygen Species Signaling

SIGNIFICANCE

Proteoglycans (PGs), besides their structural contribution, have emerged as dynamic components that mediate a multitude of cellular events. The various roles of PGs are attributed to their structure, spatial localization, and ability to act as ligands and receptors. Reactive oxygen species (ROS) are small mediators that are generated in physiological and pathological conditions. Besides their reactivity and ability to induce oxidative stress, a growing body of data suggests that ROS signaling is more relevant than direct radical damage in development of human pathologies. Recent Advances: Cell surface transmembrane PGs (syndecans, cluster of differentiation 44) represent receptors in diverse and complex transduction networks, which involve redox signaling with implications in cancer, fibrosis, renal dysfunction, or Alzheimer's disease. Through NADPH oxidase (NOX)-dependent ROS, the extracellular PG, hyaluronan is involved in osteoclastogenesis and cancer. The ROS sources, NOX1 and NOX4, increase biglycan-induced inflammation, while NOX2 is a negative regulator.

CRITICAL ISSUES

The complexity of the mechanisms that bring ROS into the light of PG biology might be the foundation of a new research area with significant promise for understanding health and disease. Important aspects need to be investigated in PG/ROS signaling: the discovery of specific targets of ROS, the precise ROS-induced chemical modifications of these targets, and the study of their pathological relevance.

FUTURE DIRECTIONS

As we become more and more aware of the interactions between PG and ROS signaling underlying intracellular communication and cell fate decisions, it is quite conceivable that this field will allow to identify new therapeutic targets.-Antioxid. Redox Signal. 27, 855-873.

Role of gp91phox in hepatic macrophage programming and alcoholic liver disease

Hepatic macrophages (MΦs) are important in the development and progression of alcoholic liver disease (ALD). This study investigates the role of gp91phox (nicotinamide adenine dinucleotide phosphate oxidase 2) in the severity of ALD and specifically in regulating hepatic MΦ efferocytic capability and the subsequent reprogramming associated with resolution of inflammation. After 4 weeks of ethanol feeding, more severe ALD developed in gp91phox-/- mice than in wild-type (WT) C57Bl/6J mice, evidenced by increased liver injury and inflammation. This phenomenon was not sex dependent, and thus the majority of experiments were performed with female mice. While total hepatic MΦ numbers did not differ between genotypes, hepatic infiltrating MΦs (IMs) were slightly more numerous in gp91phox-/- mice, and both IMs and resident Kupffer cells displayed enhanced proinflammatory and reduced tissue-restorative programming compared with these cells from WT mice. The ratio of proinflammatory IMs with higher expression of Ly6C (Ly6Chi) to anti-inflammatory IMs with lower expression of Ly6C (Ly6Clow) was significantly higher in gp91phox-/- mice compared to WT mice. Greater numbers of apoptotic cells accumulated in the liver of gp91phox-/- mice compared to WT mice, and receptors for binding and engulfing apoptotic cells were expressed at much lower levels on both Kupffer cells and IMs of gp91phox-/- mice. Interactions with apoptotic cells (binding and engulfment) in vitro were significantly fewer for gp91phox-/- MΦs than for WT MΦs, resulting in diminished expression of tissue restorative mediators by hepatic MΦs of gp91phox-/- mice. Conclusion: gp91phox plays a critical role in the differentiation of proinflammatory hepatic MΦs to a tissue-restorative phenotype, likely through programming for efferocytosis, and thereby lessens the severity of ALD. These findings enhance our understanding of the tissue environmental cues that regulate MΦ phenotypes. This knowledge could help in designing MΦ-targeting strategies to prevent and treat ALD. (Hepatology Communications 2017;1:765-779).

Successful hepatectomy for hepatic abscess with chronic granulomatous disease: a case report

BACKGROUND

Chronic granulomatous disease (CGD), a rare inherited disorder, is characterized by impaired ability of phagocytic cells to kill certain bacteria and fungi. Although liver abscess is a common manifestation of CGD, its optimal management in these patients is unknown. Here, we present a case of successful hepatectomy for hepatic abscess in a patient with CGD.

CASE PRESENTATION

An adolescent patient with previously diagnosed CGD presented to the pediatrics department of our institution with fever. Blood tests showed high concentrations of inflammatory markers. A computed tomography (CT) scan showed a multilocular mass measuring 52 mm × 34 mm in hepatic segment 4 (S4). Blood cultures were negative. Despite administration of antibiotics and γ-globulin, his fever and high concentrations of inflammatory markers persisted and the mass did not change on CT scan images. Because the medications had proved ineffective and percutaneous drainage would have been difficult because of the honeycombing in the abscess, we performed hepatic S4a + S5 anatomic resection and cholecystectomy. Culture of the excised specimen was negative. The patient's postoperative course was uneventful. On day 62, CT showed no abscess around the resection stump. On day 81, he was transferred to undergo bone marrow transplantation.

CONCLUSIONS

Surgical treatment for hepatic abscess can be effective when medical treatment has failed.

NADPH oxidase-mediated redox signaling promotes oxidative stress resistance and longevity through memo-1 in C. elegans

Transient increases in mitochondrially-derived reactive oxygen species (ROS) activate an adaptive stress response to promote longevity. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases produce ROS locally in response to various stimuli, and thereby regulate many cellular processes, but their role in aging remains unexplored. Here, we identified the C. elegans orthologue of mammalian mediator of ErbB2-driven cell motility, MEMO-1, as a protein that inhibits BLI-3/NADPH oxidase. MEMO-1 is complexed with RHO-1/RhoA/GTPase and loss of memo-1 results in an enhanced interaction of RHO-1 with BLI-3/NADPH oxidase, thereby stimulating ROS production that signal via p38 MAP kinase to the transcription factor SKN-1/NRF1,2,3 to promote stress resistance and longevity. Either loss of memo-1 or increasing BLI-3/NADPH oxidase activity by overexpression is sufficient to increase lifespan. Together, these findings demonstrate that NADPH oxidase-induced redox signaling initiates a transcriptional response that protects the cell and organism, and can promote both stress resistance and longevity.

DOI:http://dx.doi.org/10.7554/eLife.19493.001

ROS Signaling in the Pathogenesis of Acute Lung Injury (ALI) and Acute Respiratory Distress Syndrome (ARDS)

The generation of reactive oxygen species (ROS) plays an important role for the maintenance of cellular processes and functions in the body. However, the excessive generation of oxygen radicals under pathological conditions such as acute lung injury (ALI) and its most severe form acute respiratory distress syndrome (ARDS) leads to increased endothelial permeability. Within this hallmark of ALI and ARDS, vascular microvessels lose their junctional integrity and show increased myosin contractions that promote the migration of polymorphonuclear leukocytes (PMNs) and the transition of solutes and fluids in the alveolar lumen. These processes all have a redox component, and this chapter focuses on the role played by ROS during the development of ALI/ARDS. We discuss the origins of ROS within the cell, cellular defense mechanisms against oxidative damage, the role of ROS in the development of endothelial permeability, and potential therapies targeted at oxidative stress.

Mammalian target of rapamycin inhibition counterbalances the inflammatory status of immune cells in patients with chronic granulomatous disease

BACKGROUND

Chronic granulomatous disease (CGD) is a primary immunodeficiency caused by defective production of reactive oxygen species in phagocytic cells that results in life-threatening infections and severe inflammatory manifestations. The treatment of inflammatory manifestations remains challenging because it can be associated with an increased risk of infections. Previous studies have shown that phagocytes from patients with CGD display a defect in autophagy and a reactive oxygen species-independent activation of the inflammasome.

OBJECTIVE

Because the intersections between autophagy and the inflammasome have been observed in patients with various diseases and microbial infections, we investigated the possible benefit of restoring the autophagy defect through rapamycin, a potent autophagy inducer, in the setting of CGD.

METHODS

We studied 15 patients given a diagnosis of CGD and followed in our institution. All patients were free of any active infection at the time of the study.

RESULTS

We show that patients with CGD present a consistent inflammatory phenotype defined by (1) increased nonclassical and intermediate monocytes, (2) a proinflammatory state of mononuclear phagocytes with increased IL-1β and TNF-α content, (3) a T_H17 bias of CD4⁺ T cells, (4) and an increase in IL-17A-secreting neutrophil numbers. We document the reversion of CGD inflammatory status by the mammalian target of rapamycin inhibitor rapamycin on the different immune cell subsets. We also provide evidence for the enhancement of rapamycin's inhibitory effect on IL-1β secretion by the IL-1 receptor antagonist anakinra in phagocytes of patients with CGD.

CONCLUSION

Altogether, these data open new therapeutic approaches for CGD-related inflammatory manifestations.

Nrf2 Modulates Host Defense during Streptococcus pneumoniae Pneumonia in Mice

Nrf2 regulates the transcriptional response to oxidative stress. These studies tested the role of Nrf2 during Streptococcus pneumoniae pneumonia and identified Nrf2-dependent genes and pathways in lung tissue and in recruited neutrophils. Nrf2 null and wild type (WT) mice were studied at 6 and 24 h after instillation of S. pneumoniae or PBS. At 6 h, fewer neutrophils were recruited and the number of bacteria remaining in the lungs tended to be less (p = 0.06) in the Nrf2 null compared with WT mice. In uninfected lungs, 53 genes were already differentially expressed in Nrf2 null compared with WT mouse lungs, and gene sets involved in phagocytosis, Fc receptor function, complement, and Ig regulation are enhanced in PBS-treated Nrf2 null gene profiles compared with those of WT mice. These results suggest that initial host defense is enhanced in Nrf2 null mice, resulting in less recruitment of neutrophils. At 24 h, neutrophil recruitment was greater. The percentages of early apoptotic and late apoptotic/necrotic neutrophils were similar. At increasing inoculum numbers, mortality rates strikingly increased from 15 to 31 and 100% in Nrf2 null mice, whereas all WT mice survived, and Nrf2 null mice had a defect in clearance, particularly at the intermediate dose. The mortality was due to enhanced lung injury and greater systemic response. Gene profiling identified differentially regulated genes and pathways in neutrophils and lung tissue, including those involved in redox stress response, metabolism, inflammation, immunoregulatory pathways, and tissue repair, providing insight into the mechanisms for the greater tissue damage and increased neutrophil accumulation.

Nox2-derived oxidative stress results in inefficacy of antibiotics against post-influenza S. aureus pneumonia

Phagocyte oxidative burst is the primary source of lethal lung injury during influenza and MRSA coinfection.

Clinical post-influenza Staphylococcus aureus pneumonia is characterized by extensive lung inflammation associated with severe morbidity and mortality even after appropriate antibiotic treatment. In this study, we show that antibiotics rescue nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (Nox2)–deficient mice but fail to fully protect WT animals from influenza and S. aureus coinfection. Further experiments indicate that the inefficacy of antibiotics against coinfection is attributable to oxidative stress–associated inflammatory lung injury. However, Nox2-induced lung damage during coinfection was not associated with aggravated inflammatory cytokine response or cell infiltration but rather caused by reduced survival of myeloid cells. Specifically, oxidative stress increased necrotic death of inflammatory cells, thereby resulting in lethal damage to surrounding tissue. Collectively, our results demonstrate that influenza infection disrupts the delicate balance between Nox2-dependent antibacterial immunity and inflammation. This disruption leads to not only increased susceptibility to S. aureus infection, but also extensive lung damage. Importantly, we show that combination treatment of antibiotic and NADPH oxidase inhibitor significantly improved animal survival from coinfection. These findings suggest that treatment strategies that target both bacteria and oxidative stress will significantly benefit patients with influenza-complicated S. aureus pneumonia.

NOX2-dependent regulation of inflammation

NADPH oxidase (NOX) isoforms together have multiple functions that are important for normal physiology and have been implicated in the pathogenesis of a broad range of diseases, including atherosclerosis, cancer and neurodegenerative diseases. The phagocyte NADPH oxidase (NOX2) is critical for antimicrobial host defence. Chronic granulomatous disease (CGD) is an inherited disorder of NOX2 characterized by severe life-threatening bacterial and fungal infections and by excessive inflammation, including Crohn's-like inflammatory bowel disease (IBD). NOX2 defends against microbes through the direct antimicrobial activity of reactive oxidants and through activation of granular proteases and generation of neutrophil extracellular traps (NETs). NETosis involves the breakdown of cell membranes and extracellular release of chromatin and neutrophil granular constituents that target extracellular pathogens. Although the immediate effects of oxidant generation and NETosis are predicted to be injurious, NOX2, in several contexts, limits inflammation and injury by modulation of key signalling pathways that affect neutrophil accumulation and clearance. NOX2 also plays a role in antigen presentation and regulation of adaptive immunity. Specific NOX2-activated pathways such as nuclear factor erythroid 2-related factor 2 (Nrf2), a transcriptional factor that induces antioxidative and cytoprotective responses, may be important therapeutic targets for CGD and, more broadly, diseases associated with excessive inflammation and injury.

Chronic granulomatous disease

INTRODUCTION

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by recurrent, life-threatening bacterial and fungal infections of the skin, the airways, the lymph nodes, the liver, the brain and the bones. Frequently found pathogens are Staphylococcus aureus, Aspergillus species, Klebsiella species, Burkholderia cepacia, Serratia marcescens and Salmonella species.

SOURCES OF DATA

CGD is a rare (∼1:250 000 individuals) disease caused by mutations in any one of the five components of the NADPH oxidase in phagocytic leucocytes. This enzyme generates superoxide and is essential for intracellular killing of pathogens by phagocytes.

AREAS OF AGREEMENT

CGD patients suffer not only from life-threatening infections, but also from excessive inflammatory reactions.

AREAS OF CONTROVERSY

Neither the cause of these inflammatory reactions nor the way to treat them is clear.

AREAS TIMELY FOR DEVELOPING RESEARCH

Patient selection for and timing of bone marrow transplantation along with gene therapy.

Chronic granulomatous disease: Clinical, molecular, and therapeutic aspects

Chronic granulomatous disease (CGD) is a rare primary immunodeficiency caused by defects in the genes encoding any of the NADPH oxidase components responsible for the respiratory burst of phagocytic leukocytes. CGD is a genetically heterogeneous disease with an X-linked recessive (XR-CGD) form caused by mutations in the CYBB gene encoding the gp91(phox) protein, and an autosomal recessive (AR-CGD) form caused by mutations in the CYBA, NCF1, NCF2, or NCF4 genes encoding p22(phox) , p47(phox) , p67(phox) , and p40(phox) , respectively. Patients suffering from this disease are susceptible to severe life-threatening bacterial and fungal infections and excessive inflammation characterized by granuloma formation in any organ, for instance, the gastrointestinal and genitourinary tract. An early diagnosis of and the prompt treatment for these conditions are crucial for an optimal outcome of affected patients. To prevent infections, CGD patients should receive lifelong antibiotics and antifungal prophylaxis. These two measures, as well as newer more effective antimicrobials, have significantly modified the natural history of CGD, resulting in a remarkable change in overall survival, which is now around 90%, reaching well into adulthood. At present, hematopoietic stem cell transplantation (HSCT) is the only definitive treatment that can cure CGD and reverse organ dysfunction. Timing, donor selection, and conditioning regimens remain the key points of this therapy. In recent years, gene therapy (GT) for XR-CGD has been proposed as an alternative to HSCT for CGD patients without a matched donor. After the failure of the first trials performed with retroviral vectors, some groups have proposed the use of regulated SIN-lentiviral vectors targeting gp91(phox) expression in myeloid cells to increase the safety and efficacy of the GT protocols.

Accumulation of isolevuglandin-modified protein in normal and fibrotic lung

Protein lysine modification by γ-ketoaldehyde isomers derived from arachidonic acid, termed isolevuglandins (IsoLGs), is emerging as a mechanistic link between pathogenic reactive oxygen species and disease progression. However, the questions of whether covalent modification of proteins by IsoLGs are subject to genetic regulation and the identity of IsoLG-modified proteins remain unclear. Herein we show that Nrf2 and Nox2 are key regulators of IsoLG modification in pulmonary tissue and report on the identity of proteins analyzed by LC-MS following immunoaffinity purification of IsoLG-modified proteins. Gene ontology analysis revealed that proteins in numerous cellular pathways are susceptible to IsoLG modification. Although cells tolerate basal levels of modification, exceeding them induces apoptosis. We found prominent modification in a murine model of radiation-induced pulmonary fibrosis and in idiopathic pulmonary fibrosis, two diseases considered to be promoted by gene-regulated oxidant stress. Based on these results we hypothesize that IsoLG modification is a hitherto unrecognized sequelae that contributes to radiation-induced pulmonary injury and IPF.

Serum opsonin ficolin-A enhances host-fungal interactions and modulates cytokine expression from human monocyte-derived macrophages and neutrophils following Aspergillus fumigatus challenge

Invasive aspergillosis is a devastating invasive fungal disease associated with a high mortality rate in the immunocompromised, such as leukaemia patients, transplant patients and those with HIV/AIDS. The rodent serum orthologue of human L-ficolin, ficolin-A, can bind to and opsonize Aspergillus fumigatus, the pathogen that causes invasive aspergillosis, and may participate in fungal defence. Using human monocyte-derived macrophages and neutrophils isolated from healthy donors, we investigated conidial association and fungal viability by flow cytometry and microscopy. Additionally, cytokine production was measured via cytometric bead arrays. Ficolin-A opsonization was observed to significantly enhance association of conidia, while also inhibiting hyphal growth and contributing to increased fungal killing following incubation with monocyte-derived macrophages and neutrophils. Additionally, ficolin-A opsonization was capable of manifesting a decrease in IL-8, IL-1β, IL-6, IL-10 and TNF-α production from MDM and IL-1β, IL-6 and TNF-α from neutrophils 24 h post-infection. In conclusion, rodent ficolin-A is functionally comparable to human L-ficolin and is capable of modulating the innate immune response to A. fumigatus, down-regulating cytokine production and could play an important role in airway immunity.

Anti-TNF certolizumab pegol induces antioxidant response in human monocytes via reverse signaling

BACKGROUND

Anti TNF drugs have been widely used in rheumatoid arthritis (RA) but only 70 to 80 % of patients respond to this therapy. Exploring the mode of action of anti-TNF drugs remains important in order to improve the efficiency of the treatment and enhance our knowledge of inflammation. TNF-α exists as classical soluble cytokine as well as transmembrane protein (tmTNF-α). Evidence suggests that tmTNF-α can induce reverse signaling. In the present study, we have explored consequences of reverse signaling in human monocytes using certolizumab pegol (CZP).

METHODS

Monocytes were purified from healthy blood donors and were incubated with CZP. Nuclear translocation of Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) was evaluated by wide-field microscopy and cell fractionation. Heme oxygenase 1 (HO-1) was assessed by RT-qPCR and western blot. Monocytes were stimulated with lipopolysaccharide (LPS). IL-1β was quantitated by RT-qPCR. Reactive oxygen species (ROS) were evaluated by flow cytometry using the H2DCFDA fluorescent marker.

RESULTS

CZP induced rapid minimal ROS production and Nrf2 nuclear translocation. This was followed by HO-1 mRNA and protein production. IL-1β induction by LPS was inhibited at the mRNA and protein level. At a later time-point, CZP was able to counteract the strong production of ROS induced by LPS. Reverse signaling was suggested by short kinetics of Nrf2 translocation, extensive washing of CZP and the use of anti-TNF-Rs antibodies.

CONCLUSION

Our data suggest a novel mechanism of ROS modulation by CZP. This observation sheds new light on the function of reverse signaling and on potential mechanisms of action of anti-TNF drugs.

Hyperinflammation in patients with chronic granulomatous disease leads to impairment of hematopoietic stem cell functions

BACKGROUND

Defects in phagocytic nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) function cause chronic granulomatous disease (CGD), a primary immunodeficiency characterized by dysfunctional microbicidal activity and chronic inflammation.

OBJECTIVE

We sought to study the effect of chronic inflammation on the hematopoietic compartment in patients and mice with X-linked chronic granulomatous disease (X-CGD).

METHODS

We used immunostaining and functional analyses to study the hematopoietic compartment in patients with CGD.

RESULTS

An analysis of bone marrow cells from patients and mice with X-CGD revealed a dysregulated hematopoiesis characterized by increased numbers of hematopoietic progenitor cells (HPCs) at the expense of repopulating hematopoietic stem cells (HSCs). In patients with X-CGD, there was a clear reduction in the proportion of HSCs in bone marrow and peripheral blood, and they were also more rapidly exhausted after in vitro culture. In mice with X-CGD, increased cycling of HSCs, expansion of HPCs, and impaired long-term engraftment capacity were found to be associated with high concentrations of proinflammatory cytokines, including IL-1β. Treatment of wild-type mice with IL-1β induced enhanced cell-cycle entry of HSCs, expansion of HPCs, and defects in long-term engraftment, mimicking the effects observed in mice with X-CGD. Inhibition of cytokine signaling in mice with X-CGD reduced HPC numbers but had only minor effects on the repopulating ability of HSCs.

CONCLUSIONS

Persistent chronic inflammation in patients with CGD is associated with hematopoietic proliferative stress, leading to a decrease in the functional activity of HSCs. Our observations have clinical implications for the development of successful autologous cell therapy approaches.

Impaired RASGRF1/ERK-mediated GM-CSF response characterizes CARD9 deficiency in French-Canadians

BACKGROUND

Caspase recruitment domain-containing protein 9 (CARD9) deficiency is an autosomal recessive primary immunodeficiency conferring human susceptibility to invasive fungal disease, including spontaneous central nervous system candidiasis (sCNSc). However, clinical characterization of sCNSc is variable, hindering its recognition. Furthermore, an in-depth understanding of the bases for this susceptibility has remained elusive.

OBJECTIVES

We sought to comprehensively characterize sCNSc and to dissect the mechanisms by which a hypomorphic CARD9 mutation causes susceptibility to Candida species.

METHODS

We describe the clinical and radiologic findings of sCNSc caused by CARD9 deficiency in a French-Canadian cohort. We performed genetic, cellular, and molecular analyses to further decipher its pathophysiology.

RESULTS

In our French-Canadian series (n = 4) sCNSc had onset in adulthood (median, 38 years) and was often misinterpreted radiologically as brain malignancies; 1 patient had additional novel features (eg, endophthalmitis and osteomyelitis). CARD9 deficiency resulted from a hypomorphic p.Y91H mutation and allelic imbalance established in this population through founder effects. We demonstrate a consistent cellular phenotype of impaired GM-CSF responses. The ability of CARD9 to complex with B-cell CLL/lymphoma 10 (BCL10) and mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) is intact in our series, arguing against its involvement in susceptibility to fungi. Instead, we show that the p.Y91H mutation impairs the ability of CARD9 to complex with Ras protein-specific guanine nucleotide-releasing factor 1 (RASGRF1), leading to impaired activation of nuclear factor κB and extracellular signal-regulated kinase (ERK) in monocytes and subsequent GM-CSF responses. Successful treatment of a second patient with adjunctive GM-CSF bolsters the clinical relevance of these findings.

CONCLUSIONS

Hypomorphic CARD9 deficiency caused by p.Y91H results in adult-onset disease with variable penetrance and expressivity. Our findings establish the CARD9/RASGRF1/ERK/GM-CSF axis as critical to the pathophysiology of sCNSc.

The Fungal Exopolysaccharide Galactosaminogalactan Mediates Virulence by Enhancing Resistance to Neutrophil Extracellular Traps

Of the over 250 Aspergillus species, Aspergillus fumigatus accounts for up to 80% of invasive human infections. A. fumigatus produces galactosaminogalactan (GAG), an exopolysaccharide composed of galactose and N-acetyl-galactosamine (GalNAc) that mediates adherence and is required for full virulence. Less pathogenic Aspergillus species were found to produce GAG with a lower GalNAc content than A. fumigatus and expressed minimal amounts of cell wall-bound GAG. Increasing the GalNAc content of GAG of the minimally pathogenic A. nidulans, either through overexpression of the A. nidulans epimerase UgeB or by heterologous expression of the A. fumigatus epimerase Uge3 increased the amount of cell wall bound GAG, augmented adherence in vitro and enhanced virulence in corticosteroid-treated mice to levels similar to A. fumigatus. The enhanced virulence of the overexpression strain of A. nidulans was associated with increased resistance to NADPH oxidase-dependent neutrophil extracellular traps (NETs) in vitro, and was not observed in neutropenic mice or mice deficient in NADPH-oxidase that are unable to form NETs. Collectively, these data suggest that cell wall-bound GAG enhances virulence through mediating resistance to NETs.

The ubiquitous mold A. fumigatus is isolated in over 80% of all patients with invasive aspergillosis (IA). A. nidulans is a relatively non-pathogenic species that rarely causes IA except in patients with chronic granulomatous disease (CGD), a hereditary disease characterized by impaired neutrophil function due to mutations in the NADPH oxidase complex. Here, we demonstrate that one factor underlying the differences in the intrinsic virulence between A. fumigatus and A. nidulans is the amount of the exopolysaccharide galactosaminogalactan that is associated with the cell wall of these species. A. fumigatus produces higher amounts of cell wall-associated galactosaminogalactan and is more resistant than A. nidulans to neutrophil killing by NADPH-oxidase dependent extracellular traps (NETs). Increasing cell wall-associated galactosaminogalactan in A. nidulans enhanced resistance to NETs and increased the virulence of this species to the same level as A. fumigatus in mice with intact NET formation. Collectively, these data suggest that A. nidulans is more sensitive than A. fumigatus to NADPH-oxidase dependent NETosis due to lower levels of cell wall-associated GAG.

Targeted endothelial nanomedicine for common acute pathological conditions

Endothelium, a thin monolayer of specialized cells lining the lumen of blood vessels is the key regulatory interface between blood and tissues. Endothelial abnormalities are implicated in many diseases, including common acute conditions with high morbidity and mortality lacking therapy, in part because drugs and drug carriers have no natural endothelial affinity. Precise endothelial drug delivery may improve management of these conditions. Using ligands of molecules exposed to the bloodstream on the endothelial surface enables design of diverse targeted endothelial nanomedicine agents. Target molecules and binding epitopes must be accessible to drug carriers, carriers must be free of harmful effects, and targeting should provide desirable sub-cellular addressing of the drug cargo. The roster of current candidate target molecules for endothelial nanomedicine includes peptidases and other enzymes, cell adhesion molecules and integrins, localized in different domains of the endothelial plasmalemma and differentially distributed throughout the vasculature. Endowing carriers with an affinity to specific endothelial epitopes enables an unprecedented level of precision of control of drug delivery: binding to selected endothelial cell phenotypes, cellular addressing and duration of therapeutic effects. Features of nanocarrier design such as choice of epitope and ligand control delivery and effect of targeted endothelial nanomedicine agents. Pathological factors modulate endothelial targeting and uptake of nanocarriers. Selection of optimal binding sites and design features of nanocarriers are key controllable factors that can be iteratively engineered based on their performance from in vitro to pre-clinical in vivo experimental models. Targeted endothelial nanomedicine agents provide antioxidant, anti-inflammatory and other therapeutic effects unattainable by non-targeted counterparts in animal models of common acute severe human disease conditions. The results of animal studies provide the basis for the challenging translation endothelial nanomedicine into the clinical domain.

Dual oxidase 2 is essential for house dust mite-induced pro-inflammatory cytokine production in human keratinocytes

House dust mites (HDMs) are known to trigger chronic inflammation through Toll-like receptors (TLRs) and their signalling cascades. In this study, we found that TLR2 ligation by HDMs induced the activation of dual oxidase 2 (Duox2) and nuclear factor-κB (NF-κB), leading to the production of pro-inflammatory cytokines in human keratinocytes. Stimulation of human keratinocytes with HDMs resulted in increases in interleukin-8 (IL-8) and chemokine (C-C motif) ligand 20 (CCL20) levels. However, pro-inflammatory cytokine production was abolished in keratinocytes transfected with TLR2 siRNA, indicating that HDM-induced cytokine production was mediated via TLR2 signalling. We also examined the function of Duox1/2 isozymes, which are primarily expressed in keratinocytes, in HDM-mediated pro-inflammatory cytokine production. Human keratinocytes transfected with control siRNA or Duox1 siRNA showed no inhibition of IL-8 or CCL20 production in response to HDMs, whereas the silencing of Duox2 expression resulted in a failure to induce cytokine production. Moreover, the phosphorylation and nuclear localization of RelA/p65, a component of NF-κB, were induced by HDMs in human keratinocytes. Transfection of human keratinocytes with TLR2 siRNA or Duox2 siRNA resulted in the complete abolishment of RelA/p65 nuclear localization in response to HDMs. Taken together, these results indicate that the HDM-dependent TLR2-Duox2 signalling axis indeed promotes NF-κB activation, which induces IL-8 and CCL20 production and mediates epidermal keratinocyte inflammation.

Pharmacological Potential of NOX2 Agonists in Inflammatory Conditions

SIGNIFICANCE

New insights into the role of reactive oxygen species (ROS) show that activators of the phagocyte NADPH oxidase 2 (NOX2) complex have the potential to be therapeutic in autoimmune and inflammatory conditions. It is, however, essential to elucidate the consequence of targeting the NOX2 complex, as it might lead to different outcomes depending on disease context and specificity, dose, and timing of ROS production.

RECENT ADVANCES

Increasing evidence is suggesting that the role of the NOX2 complex is far more complex than previously anticipated. In addition to the well-described antimicrobial response, ROS also have immune and inflammatory regulatory effects. Compounds increasing NOX2-dependent ROS production have been shown to be effective both in preventing and in treating inflammatory manifestations in animal models of autoimmune diseases. Altogether, these results suggest the possibility of activating the NOX2 complex for the treatment of autoimmune inflammatory diseases while restoring and maintaining a balanced ROS regulation.

CRITICAL ISSUES

The complexity of the NOX system and the derived ROS is important and must be considered when designing the programs for the development of NOX2-activating drugs, as well as for validation of selected hits, to successfully identify substances effective in treating inflammatory and autoimmune conditions. In addition, it is important to consider the complex downstream immunological effects and safety for drugs that increase the production of ROS.

FUTURE DIRECTIONS

There is a strong potential for the development of ROS-inducing drugs, targeting the NOX2 complex, which are effective and safe, for the treatment of inflammatory autoimmune disorders. In such drug development, one must carefully investigate the pharmaceutical properties, including both efficacy and safety of the drugs. In addition, the immunological pathways of this new treatment strategy need careful examination.

NOX Modifiers-Just a Step Away from Application in the Therapy of Airway Inflammation?

SIGNIFICANCE

NADPH oxidase (NOX) enzymes, which are widely expressed in different airway cell types, not only contribute to the maintenance of physiological processes in the airways but also participate in the pathogenesis of many acute and chronic diseases. Therefore, the understanding of NOX isoform regulation, expression, and the manner of their potent inhibition might lead to effective therapeutic approaches.

RECENT ADVANCES

The study of the role of NADPH oxidases family in airway physiology and pathophysiology should be considered as a work in progress. While key questions still remain unresolved, there is significant progress in terms of our understanding of NOX importance in airway diseases as well as a more efficient way of using NOX modifiers in human settings.

CRITICAL ISSUES

Agents that modify the activity of NADPH enzyme components would be considered useful tools in the treatment of various airway diseases. Nevertheless, profound knowledge of airway pathology, as well as the mechanisms of NOX regulation is needed to develop potent but safe NOX modifiers.

FUTURE DIRECTIONS

Many compounds seem to be promising candidates for development into useful therapeutic agents, but their clinical potential is yet to be demonstrated. Further analysis of basic mechanisms in human settings, high-throughput compound scanning, clinical trials with new and existing molecules, and the development of new drug delivery approaches are the main directions of future studies on NOX modifiers. In this article, we discuss the current knowledge with regard to NOX isoform expression and regulation in airway inflammatory diseases as well as the aptitudes and therapeutic potential of NOX modifiers.

The serum opsonin L-ficolin is detected in lungs of human transplant recipients following fungal infections and modulates inflammation and killing of Aspergillus fumigatus

BACKGROUND

Invasive aspergillosis (IA) is a life-threatening systemic fungal infection in immunocompromised individuals that is caused by Aspergillus fumigatus. The human serum opsonin, L-ficolin, has been observed to recognize A. fumigatus and could participate in fungal defense.

METHODS

Using lung epithelial cells, primary human monocyte-derived macrophages (MDMs), and neutrophils from healthy donors, we assessed phagocytosis and killing of L-ficolin-opsonized live A. fumigatus conidia by flow cytometry and microscopy. Additionally, cytokines were measured by cytometric bead array, and L-ficolin was measured in bronchoalveolar lavage (BAL) fluid from lung transplant recipients by enzyme-linked immunosorbent assay.

RESULTS

L-ficolin opsonization increased conidial uptake and enhanced killing of A. fumigatus by MDMs and neutrophils. Opsonization was also shown to manifest an increase in interleukin 8 release from A549 lung epithelial cells but decreased interleukin 1β, interleukin 6, interleukin 8, interleukin 10, and tumor necrosis factor α release from MDMs and neutrophils 24 hours after infection. The concentration of L-ficolin in BAL fluid from patients with fungal infection was significantly higher than that for control subjects (P = .00087), and receiving operating characteristic curve analysis highlighted the diagnostic potential of L-ficolin for lung infection (area under the curve, 0.842; P < .0001).

CONCLUSIONS

L-ficolin modulates the immune response to A. fumigatus. Additionally, for the first time, L-ficolin has been demonstrated to be present in human lungs.

Immunosuppressive potential of bardoxolone methyl using a modified murine local lymph node assay (LLNA)

2-Cyano-3, 12-dioxooleana-1, 9-dien-28-oic acid methyl ester (CDDO-Me; bardoxolone methyl) is one of the synthetic oleanane triterpenoids (SOs). It is known that it is the strongest Nrf2/ARE signaling inducer of SOs and slightly inhibits immune response. Little was known about the immunomodulatory action of CDDO-Me in vivo. We assessed its immunosuppressive potential by using the modified mouse lymph node assay (LLNA) including immunosuppression-related gene expression analysis. In the modified LLNA, CDDO-Me showed a significant decrease in lymph node weight and changes in expressions of the immunosuppression-related genes, Zfp459 and Fmo2. It has been already reported that a decrease in lymph node weight was induced by several types of immunosuppressive chemicals such as calcineurin inhibitors, antimetabolites, steroids, and alkylators. In addition, changes in Zfp459 and Fmo2 expression was reported in response after only treatment of antimetabolites. From these results, CDDO-Me is considered to have an immunosuppressive action and similar mechanism to antimetabolites.

The innate immune response to Aspergillus fumigatus at the alveolar surface

Aspergillus fumigatus is an ubiquitous, saprophytic mould that forms and releases airborne conidia which are inhaled by humans on a daily basis. When the immune system is compromised (e.g. immunosuppressive therapy prior to organ transplantation) or there is pre-existing pulmonary malfunction (e.g. asthma, cystic fibrosis, TB lesions), A. fumigatus exploits weaknesses in the host defenses which can result in the development of saphrophytic, allergic or invasive aspergillosis. If not effectively eliminated by the innate immune response, conidia germinate and form invasive hyphae which can penetrate pulmonary tissues. The innate immune response to A. fumigatus is stage-specific and various components of the host's defenses are recruited to challenge the different cellular forms of the pathogen. In immunocompetent hosts, anatomical barriers (e.g. the mucociliary elevator) and professional phagocytes such as alveolar macrophages (AM) and neutrophils prevent the development of aspergillosis by inhibiting the growth of conidia and hyphae. The recognition of inhaled conidia by AM leads to the intracellular degradation of the spores and the secretion of proinflammatory mediators which recruit neutrophils to assist in fungal clearance. During the later stages of infection, dendritic cells activate a protective A. fumigatus-specific adaptive immune response which is driven by Th1 CD4(+) T cells.

Neutrophils: Between host defence, immune modulation, and tissue injury

Neutrophils, the most abundant human immune cells, are rapidly recruited to sites of infection, where they fulfill their life-saving antimicrobial functions. While traditionally regarded as short-lived phagocytes, recent findings on long-term survival, neutrophil extracellular trap (NET) formation, heterogeneity and plasticity, suppressive functions, and tissue injury have expanded our understanding of their diverse role in infection and inflammation. This review summarises our current understanding of neutrophils in host-pathogen interactions and disease involvement, illustrating the versatility and plasticity of the neutrophil, moving between host defence, immune modulation, and tissue damage.

Nrf2 regulates ROS production by mitochondria and NADPH oxidase

Background

Nuclear factor (erythroid-derived 2) factor 2 (Nrf2) is a crucial transcription factor mediating protection against oxidants. Nrf2 is negatively regulated by cytoplasmic Kelch-like ECH associated protein 1 (Keap1) thereby providing inducible antioxidant defence. Antioxidant properties of Nrf2 are thought to be mainly exerted by stimulating transcription of antioxidant proteins, whereas its effects on ROS production within the cell are uncertain.

Methods

Live cell imaging and qPCR in brain hippocampal glio-neuronal cultures and explants slice cultures with graded expression of Nrf2, i.e. Nrf2-knockout (Nrf2-KO), wild-type (WT), and Keap1-knockdown (Keap1-KD).

Results

We here show that ROS production in Nrf2-KO cells and tissues is increased compared to their WT counterparts. Mitochondrial ROS production is regulated by the Keap1–Nrf2 pathway by controlling mitochondrial bioenergetics. Surprisingly, Keap1-KD cells and tissues also showed higher rates of ROS production when compared to WT, although with a smaller magnitude. Analysis of the mRNA expression levels of the two NOX isoforms implicated in brain pathology showed, that NOX2 is dramatically upregulated under conditions of Nrf2 deficiency, whereas NOX4 is upregulated when Nrf2 is constitutively activated (Keap1-KD) to a degree which paralleled the increases in ROS production.

Conclusions

These observations suggest that the Keap1–Nrf2 pathway regulates both mitochondrial and cytosolic ROS production through NADPH oxidase.

General significance

Findings supports a key role of the Keap1–Nrf2 pathway in redox homeostasis within the cell.

•

We studied ROS production/NADPH oxidase expression in Nrf2-KO and Keap1-KD cells.

•

ROS production is increased in Nrf2-KO and Keap1-KD neurons when compared to WT.

•

NOX2/NOX4 mRNA in Nrf2-KO and Keap1-KD paralleled these changes.

Advances in the diagnosis and treatment of chronic granulomatous disease

PURPOSE OF REVIEW

Chronic granulomatous disease (CGD), characterized 50 years ago as a primary immunodeficiency disorder of phagocytic cells (resulting in failure to kill a defined spectrum of bacteria and fungi and in concomitant chronic granulomatous inflammation) now comprises five genetic defects impairing one of the five subunits of phagocyte NADPH oxidase (Phox). Phox normally generates reactive oxygen species (ROS) engaged in intracellular and extracellular host defence and resolving accompanying inflammatory processes. 'Fatal' granulomatous disease has now changed into a chronic inflammatory condition with a median survival of 35 years and is now of interest to both paediatricians and internists. Clinical vigilance and expert knowledge are needed for early recognition and tailored treatment of this relatively rare genetic disorder.

RECENT FINDINGS

Infections by unanticipated pathogens and noncirrhotic portal hypertension need to be recognized as new CGD manifestations. Adult-onset CGD too is increasingly observed even in the elderly. Conservative treatment of fungal infections needs close monitoring due to the spread of azole resistance following extensive use of azoles in agriculture. Curative haematopoietic stem cell transplantation (HSCT) in early childhood has expanded with impressive results following use of matched, unrelated or cord blood donors and of a reduced intensity conditioning (RIC) regimen. Gene therapy, however, still has major limitations, remaining experimental.

SUMMARY

CGD is more prevalent than initially believed with a birth prevalence of 1: 120 000. As patients are increasingly diagnosed around the world and grow older, further manifestations of CGD are expected. While fungal infections have lost some threat, therapeutic research focuses on two other important aims: pharmacologic cure of chronic inflammation and long-term cure of CGD by gene therapy.

Interstitial lung disease with multiple microgranulomas in chronic granulomatous disease

BACKGROUND

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease that is characterized by susceptibility to bacterial and fungal infections. CGD patients also suffer from immune regulatory disorders, such as CGD-associated bowel inflammation with granuloma, which could be caused by excessive inflammation without demonstrable infection.

PURPOSE

We investigated the clinical manifestation of interstitial lung disease (ILD) resulting from excessive inflammation in X-linked CGD patients.

METHODS

Pulmonary CT images and testing of serum KL-6 levels were performed to assess ILD in the patients. For this study, patients with pulmonary lesions due to demonstrable infections were excluded from among ILD patients.

RESULTS

Among 33 CGD patients, four developed ILD; they had increased reticulo-nodular opacities on CT images and elevated serum KL-6 levels. Histopathological examinations revealed multiple homogeneous microgranulomas in the lesions of inflammatory cell infiltration. Mononuclear cells obtained from their pulmonary lesions produced higher amounts of inflammatory cytokines than the peripheral blood mononuclear cells of CGD patients, suggesting that the only infiltrating cells in the pulmonary lesions were activated and produced large amounts of inflammatory cytokines in ILD patients. Interestingly, an anti-inflammatory drug, such as a corticosteroid or thalidomide, but not anti-bacterial or anti-fungal drugs, improved CT image findings and reduced their KL-6 levels.

CONCLUSIONS

CGD patients' daily exposures to inhaled antigens may induce excessive reactions with the production of inflammatory cytokines leading to the development of ILD with multiple microgranulomas, which could be due to an inadequate production of reactive oxygen species in CGD.

NADPH oxidase deficiency exacerbates angiotensin II-induced abdominal aortic aneurysms in mice

OBJECTIVE

Although nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2) is reportedly essential for phagocyte host defenses, it has been found to aggravate atherosclerosis in apolipoprotein E (Apoe)-null mice through excess production of superoxide. We therefore assessed the role of NOX2 in an experimental model of abdominal aortic aneurysm (AAA) and assessed the mechanism of NOX2 action in AAA.

APPROACH AND RESULTS

AAA was induced in low-density lipoprotein receptor-null (Ldlr(-/-)) mice by infusing angiotensin II. Nox2 expression was elevated in the abdominal aortae of these mice during infusion of angiotensin II, with enhanced Nox2 expression mainly because of the recruitment of NOX2-enriched macrophages into AAA lesions. Unexpectedly, systemic Nox2 deficiency promoted AAA development but reduced the level of reactive oxygen species in AAA lesions. Nox2 deficiency stimulated macrophage conversion toward the M1 subset, enhancing expression of interleukin (IL)-1β and matrix metalloproteinase-9/12 mRNA. Administration of neutralizing antibody against IL-1β abolished AAA development in Nox2-deficient mice. Bone marrow transplantation experiments revealed that AAA aggravation by Nox2 deficiency is because of bone marrow-derived cells. Isolated bone marrow-derived macrophages from Nox2-null mice could not generate reactive oxygen species. In contrast, IL-1β expression in peritoneal and bone marrow-derived macrophages, but not in peritoneal neutrophils, was substantially enhanced by Nox2 deficiency. Pharmacological inhibition of Janus kinase/signal transducers and activators of transcription signaling inhibited excess IL-1β expression in Nox2-deficient macrophages, whereas matrix metalloproteinase-9 secretion was constitutively stimulated via nuclear factor-κB signals.

CONCLUSIONS

Nox2 deficiency enhances macrophage secretion of IL-1β and matrix metalloproteinase-9, disrupting tissue-remodeling functions in AAA lesions. These actions are unfavorable if NOX2 is to serve as a molecular target for AAA.

Phagocyte NADPH oxidase restrains the inflammasome in ANCA-induced GN

ANCA-activated phagocytes cause vasculitis and necrotizing crescentic GN (NCGN). ANCA-induced phagocyte NADPH oxidase (Phox) may contribute by generating tissue-damaging reactive oxygen species. We tested an alternative hypothesis, in which Phox restrains inflammation by downregulating caspase-1, thereby reducing IL-1β generation and limiting NCGN. In an antimyeloperoxidase (anti-MPO) antibody-mediated disease model, mice transplanted with either gp91(phox)-deficient or p47(phox)-deficient bone marrow showed accelerated disease with increased crescents, necrosis, glomerular monocytes, and renal IL-1β levels compared with mice transplanted with wild-type bone marrow. IL-1β receptor blockade abrogated aggravated NCGN in gp91(phox)-deficient mice. In vitro, challenge with anti-MPO antibody strongly enhanced caspase-1 activity and IL-1β generation in gp91(phox)-deficient and p47(phox)-deficient monocytes compared with wild-type monocytes. This enhanced IL-1β generation was abrogated when caspase-1 was blocked. ANCA-induced superoxide and IL-1β generation were inversely related in human monocytes. Furthermore, transplantation of gp91(phox)/caspase-1 double-deficient bone marrow rescued the accelerated NCGN phenotype in gp91(phox) bone marrow-deficient mice. These results suggest that Phox-generated reactive oxygen species downregulate caspase-1, thereby keeping the inflammasome in check and limiting ANCA-induced inflammation. IL-1 receptor blockade may provide a promising strategy in NCGN, whereas our data question the benefit of antioxidants.

The complex roles of NADPH oxidases in fungal infection

NADPH oxidases play key roles in immunity and inflammation that go beyond the production of microbicidal reactive oxygen species (ROS). The past decade has brought a new appreciation for the diversity of roles played by ROS in signalling associated with inflammation and immunity. NADPH oxidase activity affects disease outcome during infections by human pathogenic fungi, an important group of emerging and opportunistic pathogens that includes Candida, Aspergillus and Cryptococcus species. Here we review how alternative roles of NADPH oxidase activity impact fungal infection and how ROS signalling affects fungal physiology. Particular attention is paid to roles for NADPH oxidase in immune migration, immunoregulation in pulmonary infection, neutrophil extracellular trap formation, autophagy and inflammasome activity. These recent advances highlight the power and versatility of spatiotemporally controlled redox regulation in the context of infection, and point to a need to understand the molecular consequences of NADPH oxidase activity in the cell.

Siglec-E promotes β2-integrin-dependent NADPH oxidase activation to suppress neutrophil recruitment to the lung

Siglec-E is a sialic acid-binding Ig-like lectin expressed on murine myeloid cells. It has recently been shown to function as a negative regulator of β2-integrin-dependent neutrophil recruitment to the lung following exposure to lipopolysaccharide (LPS). Here, we demonstrate that siglec-E promoted neutrophil production of reactive oxygen species (ROS) following CD11b β2-integrin ligation with fibrinogen in a sialic acid-dependent manner, but it had no effect on ROS triggered by a variety of other stimulants. Siglec-E promotion of ROS was likely mediated via Akt activation, because siglec-E-deficient neutrophils plated on fibrinogen exhibited reduced phosphorylation of Akt, and the Akt inhibitor, MK2206, blocked fibrinogen-induced ROS. In vivo imaging showed that siglec-E also promoted ROS in acutely inflamed lungs following exposure of mice to LPS. Importantly, siglec-E-promoted ROS were required for its inhibitory function, as the NADPH oxidase inhibitor, apocynin, reversed the siglec-E-mediated suppression of neutrophil recruitment and blocked neutrophil ROS production in vitro. Taken together, these results demonstrate that siglec-E functions as an inhibitory receptor of neutrophils via positive regulation of NADPH oxidase activation and ROS production. Our findings have implications for the inhibitory role of siglec-9 on human neutrophils in sepsis and acute lung injury.

NOX2 protects against progressive lung injury and multiple organ dysfunction syndrome

Systemic inflammatory response syndrome (SIRS) is a common clinical condition in patients in intensive care units that can lead to complications, including multiple organ dysfunction syndrome (MODS). MODS carries a high mortality rate, and it is unclear why some patients resolve SIRS, whereas others develop MODS. Although oxidant stress has been implicated in the development of MODS, several recent studies have demonstrated a requirement for NADPH oxidase 2 (NOX2)-derived oxidants in limiting inflammation. We recently demonstrated that NOX2 protects against lung injury and mortality in a murine model of SIRS. In the present study, we investigated the role of NOX2-derived oxidants in the progression from SIRS to MODS. Using a murine model of sterile systemic inflammation, we observed significantly greater illness and subacute mortality in gp91(phox-/y) (NOX2-deficient) mice compared with wild-type mice. Cellular analysis revealed continued neutrophil recruitment to the peritoneum and lungs of the NOX2-deficient mice and altered activation states of both neutrophils and macrophages. Histological examination showed multiple organ pathology indicative of MODS in the NOX2-deficient mice, and several inflammatory cytokines were elevated in lungs of the NOX2-deficient mice. Overall, these data suggest that NOX2 function protects against the development of MODS and is required for normal resolution of systemic inflammation.

TNFR1/phox interaction and TNFR1 mitochondrial translocation Thwart silica-induced pulmonary fibrosis

Macrophages play a fundamental role in innate immunity and the pathogenesis of silicosis. Phagocytosis of silica particles is associated with the generation of reactive oxygen species (ROS), secretion of cytokines, such as TNF, and cell death that contribute to silica-induced lung disease. In macrophages, ROS production is executed primarily by activation of the NADPH oxidase (Phox) and by generation of mitochondrial ROS (mtROS); however, the relative contribution is unclear, and the effects on macrophage function and fate are unknown. In this study, we used primary human and mouse macrophages (C57BL/6, BALB/c, and p47(phox-/-)) and macrophage cell lines (RAW 264.7 and IC21) to investigate the contribution of Phox and mtROS to silica-induced lung injury. We demonstrate that reduced p47(phox) expression in IC21 macrophages is linked to enhanced mtROS generation, cardiolipin oxidation, and accumulation of cardiolipin hydrolysis products, culminating in cell death. mtROS production is also observed in p47(phox-/-) macrophages, and p47(phox-/-) mice exhibit increased inflammation and fibrosis in the lung following silica exposure. Silica induces interaction between TNFR1 and Phox in RAW 264.7 macrophages. Moreover, TNFR1 expression in mitochondria decreased mtROS production and increased RAW 264.7 macrophage survival to silica. These results identify TNFR1/Phox interaction as a key event in the pathogenesis of silicosis that prevents mtROS formation and reduces macrophage apoptosis.

Redox-mediated signal transduction by cardiovascular Nox NADPH oxidases

The only known function of the Nox family of NADPH oxidases is the production of reactive oxygen species (ROS). Some Nox enzymes show high tissue-specific expression and the ROS locally produced are required for synthesis of hormones or tissue components. In the cardiovascular system, Nox enzymes are low abundant and function as redox-modulators. By reacting with thiols, nitric oxide (NO) or trace metals, Nox-derived ROS elicit a plethora of cellular responses required for physiological growth factor signaling and the induction and adaptation to pathological processes. The interactions of Nox-derived ROS with signaling elements in the cardiovascular system are highly diverse and will be detailed in this article, which is part of a Special Issue entitled "Redox Signalling in the Cardiovascular System".

NADPH oxidase promotes neutrophil extracellular trap formation in pulmonary aspergillosis

NADPH oxidase is a crucial enzyme in antimicrobial host defense and in regulating inflammation. Chronic granulomatous disease (CGD) is an inherited disorder of NADPH oxidase in which phagocytes are defective in generation of reactive oxidant intermediates. Aspergillus species are ubiquitous, filamentous fungi, which can cause invasive aspergillosis, a major cause of morbidity and mortality in CGD, reflecting the critical role for NADPH oxidase in antifungal host defense. Activation of NADPH oxidase in neutrophils can be coupled to the release of proteins and chromatin that comingle in neutrophil extracellular traps (NETs), which can augment extracellular antimicrobial host defense. NETosis can be driven by NADPH oxidase-dependent and -independent pathways. We therefore undertook an analysis of whether NADPH oxidase was required for NETosis in Aspergillus fumigatus pneumonia. Oropharyngeal instillation of live Aspergillus hyphae induced neutrophilic pneumonitis in both wild-type and NADPH oxidase-deficient (p47(phox-/-)) mice which had resolved in wild-type mice by day 5 but progressed in p47(phox-/-) mice. NETs, identified by immunostaining, were observed in lungs of wild-type mice but were absent in p47(phox-/-) mice. Using bona fide NETs and nuclear chromatin decondensation as an early NETosis marker, we found that NETosis required a functional NADPH oxidase in vivo and ex vivo. In addition, NADPH oxidase increased the proportion of apoptotic neutrophils. Together, our results show that NADPH oxidase is required for pulmonary clearance of Aspergillus hyphae and generation of NETs in vivo. We speculate that dual modulation of NETosis and apoptosis by NADPH oxidase enhances antifungal host defense and promotes resolution of inflammation upon infection clearance.

CaMKII is essential for the proasthmatic effects of oxidation

Increased reactive oxygen species (ROS) contribute to asthma, but little is known about the molecular mechanisms connecting increased ROS with characteristic features of asthma. We show that enhanced oxidative activation of the Ca(2+)/calmodulin-dependent protein kinase (ox-CaMKII) in bronchial epithelium positively correlates with asthma severity and that epithelial ox-CaMKII increases in response to inhaled allergens in patients. We used mouse models of allergic airway disease induced by ovalbumin (OVA) or Aspergillus fumigatus (Asp) and found that bronchial epithelial ox-CaMKII was required to increase a ROS- and picrotoxin-sensitive Cl(-) current (ICl) and MUC5AC expression, upstream events in asthma progression. Allergen challenge increased epithelial ROS by activating NADPH oxidases. Mice lacking functional NADPH oxidases due to knockout of p47 and mice with epithelial-targeted transgenic expression of a CaMKII inhibitory peptide or wild-type mice treated with inhaled KN-93, an experimental small-molecule CaMKII antagonist, were protected against increases in ICl, MUC5AC expression, and airway hyperreactivity to inhaled methacholine. Our findings support the view that CaMKII is a ROS-responsive, pluripotent proasthmatic signal and provide proof-of-concept evidence that CaMKII is a therapeutic target in asthma.

A subanesthetic dose of isoflurane during postconditioning ameliorates zymosan-induced neutrophil inflammation lung injury and mortality in mice

Anesthetic isoflurane (ISO) has immunomodulatory effects. In the present study, we investigated whether a subanesthetic dose of ISO (0.7%) protected against zymosan (ZY) induced inflammatory responses in the murine lung and isolated neutrophils. At 1 and 6 hrs after ZY administration intraperitoneally, ISO was inhaled for 1 hr, and 24 hrs later, lung inflammation and injury were assessed. We found that ISO improved the survival rate of mice and mitigated lung injury as characterized by the histopathology, wet-to-dry weight ratio, protein leakage, and lung function index. ISO significantly attenuated ZY-induced lung neutrophil recruitment and inflammation. This was suggested by the downregulation of (a) endothelial adhesion molecule expression and myeloperoxidase (MPO) activity in lung tissue and polymorphonuclear neutrophils (b) chemokines, and (c) proinflammatory cytokines in BALF. Furthermore, ZY-induced nuclear translocation and DNA-binding activity of NF- κ B p65 were also reduced by ISO. ISO treatment inhibited iNOS expression and activity, as well as subsequent nitric oxide generation. Consistent with these in vivo observations, in vitro studies confirmed that ISO blocked NF- κ B and iNOS activation in primary mouse neutrophils challenged by ZY. These results provide evidence that 0.7% ISO ameliorates inflammatory responses in ZY-treated mouse lung and primary neutrophils.

Deficiency of gp91phox inhibits allergic airway inflammation

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, a multienzyme complex, is the major source for production of reactive oxygen species (ROS). ROS are increased in allergic diseases, such as asthma, but the role of ROS in disease pathogenesis remains uncertain. We hypothesized that mice unable to generate ROS via the NADPH oxidase pathway would have decreased allergic airway inflammation. To test this hypothesis, we studied gp91phox(-/-) mice in a model of allergic airway inflammation after sensitization and challenge with ovalbumin. Serum, bronchoalveolar lavage fluid, and lungs were then examined for evidence of allergic inflammation. We found that mice lacking a functional NADPH oxidase complex had significantly decreased ROS production and allergic airway inflammation, compared with wild-type (WT) control animals. To determine the mechanism by which allergic inflammation was inhibited by gp91phox deficiency, we cultured bone marrow-derived dendritic cells from WT and gp91phox(-/-) mice and activated them with LPS. IL-12 expression was significantly increased in the gp91phox(-/-) bone marrow-derived dendritic cells, suggesting that the cytokine profile produced in the absence of gp91phox enhanced the conditions leading to T helper (Th) type 1 differentiation, while inhibiting Th2 polarization. Splenocytes from sensitized gp91phox(-/-) animals produced significantly less IL-13 in response to ovalbumin challenge in vitro compared with splenocytes from sensitized WT mice, suggesting that NADPH oxidase promotes allergic sensitization. In contrast, inflammatory cytokines produced by T cells cultured from WT and gp91phox(-/-) mice under Th0, Th1, Th2, and Th17 conditions were not significantly different. This study demonstrates the importance of NADPH oxidase activity and ROS production in a murine model of asthma.

Targeted Drug Delivery to Endothelial Adhesion Molecules

Endothelial cells represent important targets for therapeutic and diagnostic interventions in many cardiovascular, pulmonary, neurological, inflammatory, and metabolic diseases. Targeted delivery of drugs (especially potent and labile biotherapeutics that require specific subcellular addressing) and imaging probes to endothelium holds promise to improve management of these maladies. In order to achieve this goal, drug cargoes or their carriers including liposomes and polymeric nanoparticles are chemically conjugated or fused using recombinant techniques with affinity ligands of endothelial surface molecules. Cell adhesion molecules, constitutively expressed on the endothelial surface and exposed on the surface of pathologically altered endothelium—selectins, VCAM-1, PECAM-1, and ICAM-1—represent good determinants for such a delivery. In particular, PECAM-1 and ICAM-1 meet criteria of accessibility, safety, and relevance to the (patho)physiological context of treatment of inflammation, ischemia, and thrombosis and offer a unique combination of targeting options including surface anchoring as well as intra- and transcellular targeting, modulated by parameters of the design of drug delivery system and local biological factors including flow and endothelial phenotype. This review includes analysis of these factors and examples of targeting selected classes of therapeutics showing promising results in animal studies, supporting translational potential of these interventions.

IL-17C expression in nasal epithelial cells of chronic rhinosinusitis with nasal polyposis

Interleukin 17C (IL-17C) is a functionally distinct member of the IL-17 family that is selectively induced in epithelia by bacterial challenge and inflammatory stimuli. The goal of this study was to explore the expression of IL-17C in nasal epithelial cells and their role in the pathogenesis of chronic rhinosinusitis with nasal polyposis (CRSwNPs). IL-17C expression was detected using immunohistochemistry (IHC) of the epithelial cell layers and using the western blot assay on whole tissue homogenates from control subjects (n = 10) and CRSwNP patients [10 non-eosinophilic polyps and 10 eosinophilic polyps (EPs)]. Expression of IL-17C and P47-phox were evaluated in the human nasal epithelial cells (RPMI-2650 cells) after treatment with staphylococcal enterotoxin B (SEB) and pretreatment with reactive oxygen species (ROS) scavenger, N-acetyl L-cysteine (NAC). Finally, IL-17C expression was demonstrated in eosinophilic rhinosinusitis murine model using IHC. Epithelial expression of IL-17C was higher in nasal polyps (especially in EPs) compared to control mucosa. SEB increased the expression of IL-17C and P47-phox in RPMI-2650 cells. SEB-induced expressions of both IL-17C and P47-phox were significantly decreased in NAC-pretreated cells. Epithelial expression of IL-17C was significantly higher in experimental mice compared to control mice. SEB-induced IL-17C expression in nasal epithelial cells is mediated by ROS production. This pathway may be associated with the pathogenesis of CRSwNP, especially eosinophilic nasal polyps.

Myeloid-derived suppressor cells modulate immune responses independently of NADPH oxidase in the ovarian tumor microenvironment in mice

The phagocyte NADPH oxidase generates superoxide anion and downstream reactive oxidant intermediates in response to infectious threat, and is a critical mediator of antimicrobial host defense and inflammatory responses. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of immature myeloid cells that are recruited by cancer cells, accumulate locally and systemically in advanced cancer, and can abrogate anti-tumor immunity. Prior studies have implicated the phagocyte NADPH oxidase as being an important component promoting MDSC accumulation and immunosuppression in cancer. We therefore used engineered NADPH oxidase-deficient (p47 (phox-/-)) mice to delineate the role of this enzyme complex in MDSC accumulation and function in a syngeneic mouse model of epithelial ovarian cancer. We found that the presence of NADPH oxidase did not affect tumor progression. The accumulation of MDSCs locally and systemically was similar in tumor-bearing wild-type (WT) and p47 (phox-/-) mice. Although MDSCs from tumor-bearing WT mice had functional NADPH oxidase, the suppressive effect of MDSCs on ex vivo stimulated T cell proliferation was NADPH oxidase-independent. In contrast to other tumor-bearing mouse models, our results show that MDSC accumulation and immunosuppression in syngeneic epithelial ovarian cancer is NADPH oxidase-independent. We speculate that factors inherent to the tumor, tumor microenvironment, or both determine the specific requirement for NADPH oxidase in MDSC accumulation and function.

Pulmonary manifestations of chronic granulomatous disease

Chronic granulomatous disease (CGD) is an inherited disorder, characterized by defects in superoxide-generating NADPH oxidase of phagocytes. The genetic defects in CGD induce failure to activate the respiratory burst in the phagocytes, leading to severe recurrent infections and unexplained prolonged inflammatory reactions that may produce granulomatous lesions. A noble advance in curative therapy for CGD is hematopoietic stem cell transplantation. Since the most common site of involvement in CGD is the lung, the pulmonologists (pediatrics or adult) may be among the first to recognize the pattern of infection, inflammation and granuloma formation, leading to diagnosis of CGD. Pulmonologists need to be aware of different lung manifestations of CGD.

Crohn's as an immune deficiency: from apparent paradox to evolving paradigm

Crohn's disease is often considered an autoimmune condition, based on the observations of a histopathological inflammatory process in the absence of identifiable causal microorganism(s) and that immune-modulating therapeutics result in diminished host-directed inflammatory pathology. However, the evidence for a self-targeted immune response is unproven; thus, the instigating and perpetuating forces that drive this chronic inflammation remain unknown. In recent years, a convergence of findings from different fields of investigation has led to a new paradigm, where Crohn's disease appears to be the consequence of an intrinsic innate immune deficiency. While genomic/postgenomic studies and functional immunologic investigations offer a common perspective, critical details of the processes involved require further elaboration. In this review, we place this new model in the context of the emerging literature on non-HIV immune deficiencies, to compare and contrast what is known about proven intrinsic (primary) immune deficiencies to the nascent understanding of Crohn's disease. We then re-evaluate postgenomic research, looking at the functional importance of Crohn's disease-associated mutations and polymorphisms, to delineate points of consensus and issues requiring further study. We ask whether the immunologic profile can guide predictions as to which microbial triggers could exploit these defects and thereby initiate and/or perpetuate chronic enteritis. Finally, we outline potential clinical implications of this model, from immunologic assessment of patients to the selection of therapeutic interventions.