Essential role of nuclear factor-kappaB for NADPH oxidase activity in normal and anhidrotic ectodermal dysplasia leukocytes

Vinblastine resets tumor-associated macrophages toward M1 phenotype and promotes antitumor immune response

BACKGROUND

Massive tumor-associated macrophage (TAM) infiltration is observed in many tumors, which usually display the immune-suppressive M2-like phenotype but can also be converted to an M1-like antitumor phenotype due to their high degree of plasticity. The macrophage polarization state is associated with changes in cell shape, macrophage morphology is associated with activation status. M1 macrophages appeared large and rounded, while M2 macrophages were stretched and elongated cells. Manipulating cell morphology has been shown to affect the polarization state of macrophages. The shape of the cell is largely dependent on cytoskeletal proteins, especially, microtubules. As a microtubule-targetting drug, vinblastine (VBL) has been used in chemotherapy. However, no study to date has explored the effect of VBL on TAM shape changes and its role in tumor immune response.

METHOD

We used fluorescent staining of the cytoskeleton and quantitative analysis to reveal the morphological differences between M0, M1, M2, TAM and VBL-treated TAM. Flow cytometry was used to confirm the polarization states of these macrophages using a cell surface marker-based classification. In vivo antibody depletion experiments in tumor mouse models were performed to test whether macrophages and CD8+ T cell populations were required for the antitumor effect of VBL. VBL and anti-PD-1 combination therapy was then investigated in comparison with monotherapy. RNA-seq of TAM of treated and untreated with VBL was performed to explore the changes in pathway activities. siRNA mediated knockdown experiments were performed to verify the target pathway that was affected by VBL treatment.

RESULTS

Here, we showed that VBL, an antineoplastic agent that destabilizes microtubule, drove macrophage polarization into the M1-like phenotype both in vitro and in tumor models. The antitumor effect of VBL was attenuated in the absence of macrophages or CD8+ T cells. Mechanistically, VBL induces the activation of NF-κB and Cyba-dependent reactive oxygen species generation, thus polarizing TAMs to the M1 phenotype. In parallel, VBL promotes the nuclear translocation of transcription factor EB, inducing lysosome biogenesis and a dramatic increase in phagocytic activity in macrophages.

CONCLUSIONS

This study explored whether manipulating cellular morphology affects macrophage polarization and consequently induces an antitumor response. Our data reveal a previously unrecognized antitumor mechanism of VBL and suggest a drug repurposing strategy combining VBL with immune checkpoint inhibitors to improve malignant tumor immunotherapy.

The role of mitochondrial ROS in antibacterial immunity

Reactive oxygen species (ROS) are essential participants of various innate immune cell responses against microorganisms and are also involved in many cellular regulatory pathways. It was believed that the main pool of ROS in the innate immune cells is generated by the NADPH oxidase enzymatic complex. However, it was discovered recently that mitochondrial ROS (mtROS) are equally important for the functioning of the immune system. mtROS play an important role in the development of the antimicrobial innate immune responses. The present mini-review summarizes the most recent data on the role of mtROS in the antibacterial immunity. The principles of mtROS formation and possible mechanisms of their generation under the activation of innate immunity are highlighted in this review. We also speculate on the possibilities of using activators of mtROS production in clinical practice.

Regulation of CYBB Gene Expression in Human Phagocytes by a Distant Upstream NF-κB Binding Site

The human CYBB gene encodes the gp91-phox component of the phagocyte oxidase enzyme complex, which is responsible for generating superoxide and other downstream reactive oxygen species essential to microbial killing. In the present study, we have identified by sequence analysis a putative NF-κB binding site in a DNase I hypersensitive site, termed HS-II, located in the distant 5' flanking region of the CYBB gene. Electrophoretic mobility assays showed binding of the sequence element by recombinant NF-κB protein p50 and by proteins in nuclear extract from the HL-60 myeloid leukemia cell line corresponding to p50 and to p50/p65 heterodimers. Chromatin immunoprecipitation demonstrated NF-κB binding to the site in intact HL-60 cells. Chromosome conformation capture (3C) assays demonstrated physical interaction between the NF-κB binding site and the CYBB promoter region. Inhibition of NF-κB activity by salicylate reduced CYBB expression in peripheral blood neutrophils and differentiated U937 monocytic leukemia cells. U937 cells transfected with a mutant inhibitor of κB "super-repressor" showed markedly diminished CYBB expression. Luciferase reporter analysis of the NF-κB site linked to the CYBB 5' flanking promoter region revealed enhanced expression, augmented by treatment with interferon-γ. These studies indicate a role for this distant, 15 kb upstream, binding site in NF-κB regulation of the CYBB gene, an essential component of phagocyte-mediated host defense.

Regulating effect of activated NF-κB on edema induced by traumatic brain injury of rats

OBJECTIVE

To observe the effect of nuclear transcription factor-κB (NF-κB) on cerebral edema in rats with traumatic brain injury (TBI).

METHODS

Male SD rats with fluid percussion injury (FPI) were selected. After separation and culture, rats' astrocytes all suffered FPI. The expression of NF-κB and the water content were detected at the animal and cellular levels, while the activity of NOX was evaluated at the cellular level.

RESULTS

According to the results, the positive expression of NF-κB and expression of mRNA were significantly increased and the water content was increased for rats after TBI, while NF-κB inhibitor BAY11-7082 could significantly reduce the effect of TBI. 1 and 3 h after FPI of astrocytes, the activation of NF-κB was increased and BAY 11-7082 could significantly improve the injury-induced swelling of astrocytes. After the injury of astrocytes, the activity of NOX was also increased, while BAY 11-7082 could reduce the activity of NOX.

CONCLUSIONS

The results show that the activation of NF-κB in astrocytes is a key factor in the process of cerebral edema after TBI of rats.

Activation of NF-κB mediates astrocyte swelling and brain edema in traumatic brain injury

Brain edema and associated increased intracranial pressure are major consequences of traumatic brain injury (TBI). While astrocyte swelling (cytotoxic edema) represents a major component of the brain edema in the early phase of TBI, its mechanisms are unclear. One factor known to be activated by trauma is nuclear factor-κB (NF-κB). Because this factor has been implicated in the mechanism of cell swelling/brain edema in other neurological conditions, we examined whether NF-κB might also be involved in the mediation of post-traumatic astrocyte swelling/brain edema. Here we show an increase in NF-κB activation in cultured astrocytes at 1 and 3 h after trauma (fluid percussion injury, FPI), and that BAY 11-7082, an inhibitor of NF-κB, significantly blocked the trauma-induced astrocyte swelling. Increased activities of nicotinamide adenine dinucleotide phosphate-oxidase and the Na(+), K(+), 2Cl(-) cotransporter were also observed in cultured astrocytes after trauma, and BAY 11-7082 reduced these effects. We also examined the role of NF-κB in the mechanism of cell swelling by using astrocyte cultures derived from transgenic (Tg) mice with a functional inactivation of astrocytic NF-κB. Exposure of cultured astrocytes from wild-type mice to in vitro trauma (3 h) caused a significant increase in cell swelling. By contrast, traumatized astrocyte cultures derived from NF-κB Tg mice showed no swelling. We also found increased astrocytic NF-κB activation and brain water content in rats after FPI, while BAY 11-7082 significantly reduced such effects. Our findings strongly suggest that activation of astrocytic NF-κB represents a key element in the process by which cytotoxic brain edema occurs after TBI.

Pediatric allergy and immunology in Brazil

The subspecialty of pediatric allergy and immunology in Brazil is in its early years and progressing steadily. This review highlights the research developed in the past years aiming to show the characteristics of allergic and immunologic diseases in this vast country. Epidemiologic studies demonstrated the high prevalence of asthma in infants, children, and adolescents. Mortality rates and average annual variation of asthma hospitalization have reduced in all pediatric age groups. Indoor aeroallergen exposure is excessively high and contributes to the high rates of allergy sensitization. Prevalence of food allergy has increased to epidemic levels. Foods (35%), insect stings (30%), and drugs (23%) are the main etiological agents of anaphylaxis in children and adolescents. Molecular diagnosis of primary immunodeficiencies (PID) showed a high incidence of fungal infections including paracoccidioidomycosis in X-linked hyper-IgM syndrome, and the occurrence of BCG adverse reactions or other mycobacterial infections in patients with chronic granulomatous disease. Education in pediatric allergy and immunology is deficient for medical students, but residency programs are effective in training internists and pediatricians for the practice of allergy. The field of PID requires further training. Last, this review is a tribute to Prof. Dr. Charles Naspitz, one of the pioneers of our specialty in Brazil.

BAY 41-2272, a soluble guanylate cyclase agonist, activates human mononuclear phagocytes

BACKGROUND AND PURPOSE

Phagocyte function is critical for host defense against infections. Defects in phagocytic function lead to several primary immunodeficiencies characterized by early onset of recurrent and severe infections. In this work, we further investigated the effects of BAY 41-2272, a soluble guanylate cyclase (sGC) agonist, on the activation of human peripheral blood monocytes (PBM) and THP-1 cells.

EXPERIMENTAL APPROACH

THP-1 cells and PBM viability was evaluated by methylthiazoletetrazolium assay; reactive oxygen species production by lucigenin chemiluminescence; gene and protein expression of NAPDH oxidase components by qRT-PCR and Western blot analysis, respectively; phagocytosis and microbicidal activity by co-incubation, respectively, with zymosan and Escherichia coli; and cytokine release by elisa.

KEY RESULTS

BAY 41-2272, compared with the untreated group, increased spreading of monocytes by at least 35%, superoxide production by at least 50%, and gp91(PHOX) and p67(PHOX) gene expression 20 to 40 times, in both PBM and THP-1 cells. BAY 41-2272 also augmented phagocytosis of zymosan particles threefold compared with control, doubled microbicidal activity against E. coli and enhanced the release of TNF-α and IL-12p70 by both PBM and THP-1 cells. Finally, by inhibiting sGC with ODQ, we showed that BAY 41-2272-induced superoxide production and phagocytosis is not dependent exclusively on sGC activation.

CONCLUSIONS AND IMPLICATIONS

In addition to its ability to induce vasorelaxation and its potential application for therapy of vascular diseases, BAY 41-2272 was shown to activate human mononuclear phagocytes. Hence, it is a novel pro-inflammatory drug that may be useful for controlling infections in the immunocompromised host.

Regulation of innate immunity by NADPH oxidase

NADPH oxidase is a critical regulator of both antimicrobial host defense and inflammation. Activated in nature by microbes and microbial-derived products, the phagocyte NADPH oxidase is rapidly assembled, and generates reactive oxidant intermediates (ROIs) in response to infectious threat. Chronic granulomatous disease (CGD) is an inherited disorder of the NADPH oxidase characterized by recurrent and severe bacterial and fungal infections, and pathology related to excessive inflammation. Studies in CGD patients and CGD mouse models indicate that NADPH oxidase plays a key role in modulating inflammation and injury that is distinct from its antimicrobial function. The mechanisms by which NADPH oxidase mediates killing of pathogens and regulation of inflammation have broad relevance to our understanding of normal physiological immune responses and pathological states, such as acute lung injury and bacterial or fungal infections.

Regulation of NADPH oxidase gene expression with PKA and cytokine IL-4 in neurons and microglia

Neuronal excitation is mediated by the activation of NMDA receptor and associated with the formation of reactive oxygen species due to the activation of NADPH oxidase complex proteins. The activation of Gs protein coupled receptors (GPCRs) induces neuronal activation in the cAMP-dependent protein kinase A (PKA)-mediated signal cascade and regulates NADPH oxidase activity. However, it is unknown whether PKA regulates NADPH oxidase gene expression in neurons and microglia. In the present research, the NADPH oxidase gene expression was studied in rat cortical neurons and microglia in vitro. Purified microglial cells were identified with OX-42 antibody and they also expressed apolipoprotein E (ApoE). The time-dependent effect of cytokine interleukin-4 (IL-4) (20 ng/ml) in NADPH oxidase gene expression was studied in microglial cells. The levels of mRNA were determined by quantitative RT-PCR. The expression of NOX1, NOX2, and NCF2 was upregulated after IL-4 treatment for 4 h, but it was downregulated after 8-24 h. The expression of NCF1 was suppressed during any time of cytokine effect. IL-4 upregulated arginase1 (Arg1) and serine racemase1 (SRR1) gene expressions in microglia. Amyloid beta (Ab) suppressed NOX2, NCF1, and NCF2 gene expressions and upregulated glutamate cystine transporter (xCT), although IL-4 attenuated the effect of Ab (500 μM) in the upregulation of xCT gene expression. The activation of PKA with agonist dibutyryl cAMP (dbcAMP) (100 μM) induced the upregulation of Arg1 gene expression in microglia involving in the process of microglial activation. The transcription of NOX1, NOX2, and NCF1 was suppressed in microglial cells after dbcAMP treatment within 24 h. Neurons were identified with the microtubule-associated protein tau. The uniform distribution of tau along axons was established in normal neurons. Tau protein was redistributed after PKA agonist dbcAMP treatment for 24 h. L-glutamate (50 μM) caused the apoptotic processes and the accumulation of tau in the soma of neurons and along axons. The activation of PKA for 24 h induced the transcriptional upregulation of NOX1 and NCF1 in cortical neurons. However, L-glutamate suppressed NOX1 gene expression in neurons. These data demonstrate that the effects of IL-4 and dbcAMP are similar in the regulation of SRR1, Arg1, and NADPH oxidase complex gene expressions in neurons and microglia. IL-4 prevents glutamate release from microglia suppressing xCT expression induced by Ab. These findings suggest that the activation of GPCR in PKA-mediated pathway leads to transcriptional regulation of NADPH oxidase complex. The modulation of GPCR activation may inhibit the oxidative stress in neurons.

Advances in primary immunodeficiency diseases in Latin America: epidemiology, research, and perspectives

Primary immunodeficiencies (PIDs) are genetic disorders of the immune system comprising many different phenotypes. Although previously considered rare, recent advances in their clinical, epidemiological, and molecular definitions are revealing how much we still need to learn about them. For example, geographical and ethnic variations as well as the impact of certain practices influence their frequency and presentation, making it necessary to consider their study in terms of regions. The Latin American Society for Immunodeficiencies was established as an organization dedicated to provide scientific support for basic and clinical research and to develop tools and educational resources to promote awareness in the medical community. Initiatives such as these are positively influencing the way PIDs are tackled in these countries, as shown by recent reports and publications. This paper provides a historical compilation and a current view of the many issues faced by scientists studying these diseases in these countries, highlighting the diverse scientific contributions and offering a promising perspective for the further developments in this field in Latin America.

The human NADPH oxidase: primary and secondary defects impairing the respiratory burst function and the microbicidal ability of phagocytes

Phagocytes, such as granulocytes and monocytes/macrophages, contain a membrane-associated NADPH oxidase that produces superoxide leading to other reactive oxygen species with microbicidal, tumoricidal and inflammatory activities. Primary defects in oxidase activity in chronic granulomatous disease (CGD) lead to severe, life-threatening infections that demonstrate the importance of the oxygen-dependent microbicidal system in host defence. Other immunological disturbances may secondarily affect the NADPH oxidase system, impair the microbicidal activity of phagocytes and predispose the host to recurrent infections. This article reviews the primary defects of the human NADPH oxidase leading to classical CGD, and more recently discovered immunological defects secondarily affecting phagocyte respiratory burst function and resulting in primary immunodeficiencies with varied phenotypes, including susceptibilities to pyogenic or mycobacterial infections.

NAD(P)H oxidase participates in the palmitate-induced superoxide production and insulin secretion by rat pancreatic islets

Nicotinamide adenine dinucleotide phosphate [NAD(P)H] oxidase complex has been shown to be involved in the process of glucose-stimulated insulin secretion (GSIS). In this study, we examined the effect of palmitic acid on superoxide production and insulin secretion by rat pancreatic islets and the mechanism involved. Rat pancreatic islets were incubated during 1 h with 1 mM palmitate, 1% fatty acid free-albumin, 5.6 or 10 mM glucose and in the presence of inhibitors of NAD(P)H oxidase (DPI--diphenyleneiodonium), PKC (calphostin C) and carnitine palmitoyl transferase-I (CPT-I) (etomoxir). Superoxide content was determined by hydroethidine assays. Palmitate increased superoxide production in the presence of 5.6 and 10 mM glucose. This effect was dependent on activation of PKC and NAD(P)H oxidase. Palmitic acid oxidation was demonstrated to contribute for the fatty acid induction of superoxide production in the presence of 5.6 mM glucose. In fact, palmitate caused p47(PHOX) translocation to plasma membrane, as shown by immunohistochemistry. Exposure to palmitate for 1 h up-regulated the protein content of p47(PHOX) and the mRNA levels of p22(PHOX), gp91(PHOX), p47(PHOX), proinsulin and the G protein-coupled receptor 40 (GPR40). Fatty acid stimulation of insulin secretion in the presence of high glucose concentration was reduced by inhibition of NAD(P)H oxidase activity. In conclusion, NAD(P)H oxidase is an important source of superoxide in pancreatic islets and the activity of NAD(P)H oxidase is involved in the control of insulin secretion by palmitate.

NF-κB in the mechanism of brain edema in acute liver failure: studies in transgenic mice

Astrocyte swelling and brain edema are major complications of the acute form of hepatic encephalopathy (acute liver failure, ALF). While elevated brain ammonia level is a well-known etiological factor in ALF, the mechanism by which ammonia brings about astrocyte swelling is not well understood. We recently found that astrocyte cultures exposed to ammonia activated nuclear factor-κB (NF-κB), and that pharmacological inhibition of such activation led to a reduction in astrocyte swelling. Although these findings suggest the involvement of NF-κB in astrocyte swelling in vitro, it is not known whether NF-κB contributes to the development of brain edema in ALF in vivo. Furthermore, pharmacological agents used to inhibit NF-κB may have non-specific effects. Accordingly, we used transgenic (Tg) mice that have a functional inactivation of astrocytic NF-κB and examined whether these mice are resistant to ALF-associated brain edema. ALF was induced in mice by treatment with the hepatotoxin thioacetamide (TAA). Wild type (WT) mice treated with TAA showed a significant increase in brain water content (1.65%) along with prominent astrocyte swelling and spongiosis of the neuropil, consistent with the presence of cytotoxic edema. These changes were not observed in Tg mice treated with TAA. Additionally, WT mice with ALF showed an increase in inducible nitric oxide synthase (iNOS) immunoreactivity in astrocytes from WT mice treated with TAA (iNOS is known to be activated by NF-κB and to contribute to cell swelling). By contrast, Tg mice treated with TAA did not exhibit brain edema, histological changes nor an increase in iNOS immunoreactivity. We also examined astrocytes cultures derived from Tg mice to determine whether these cells exhibit a lesser degree of swelling and cytopathological changes following exposure to ammonia. Astrocyte cultures derived from Tg mice showed no cell swelling nor morphological abnormalities when exposed to ammonia for 24h. By contrast, ammonia significantly increased cell swelling (31.7%) in cultured astrocytes from WT mice and displayed cytological abnormalities. Moreover, we observed a lesser increment in iNOS and NADPH oxidase activity (the latter is also known to be activated by NF-κB and to contribute to astrocyte swelling) in astrocyte cultures from Tg mice treated with ammonia, as compared to ammonia-treated WT mice astrocytes. These findings strongly suggest that activation of NF-κB is a critical factor in the development of astrocyte swelling/brain edema in ALF.

Polymorphonuclear cell priming associated with NF-kB activation in patients with severe injury is partially dependent on macrophage migration inhibitory factor

BACKGROUND

Severe trauma may induce alternations of cytokine response and polymorphonuclear cell (PMN) activity in patients. This study investigated the correlation of plasma migration inhibitory factor (MIF) level and PMN activation after severe injury, and their relationship with clinical outcomes.

STUDY DESIGN

A prospective observational study was performed at the emergency department and intensive care unit of a university hospital. Thirty-two severe blunt trauma patients (Injury Severity Score greater than 16) with systemic inflammatory response syndrome (SIRS) were enrolled. Age- and gender-matched healthy persons were the controls. Patient blood samples were obtained within 24 hours of and at 72 hours after injury. PMNs were isolated and measured for NF-kBp65 translocation and respiratory burst. Plasma MIF, tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-8, and IL-10 concentrations were measured. Control PMNs were incubated with patient plasma preincubated with anti-MIF antibody or anti-IL-6 antibody; cytokine blockade effects were evaluated.

RESULTS

Twelve patients developed organ failure. Compared with patients without organ failure, patients with organ failure had lower blood pressure and a higher base deficit on admission, higher NF-kBp65 translocation and respiratory burst of PMNs, and higher plasma MIF (968 ± 246 pg/mL vs 564 ± 299 pg/mL) and IL-6 (202 ± 91 pg/mL vs 119 ± 84 pg/mL) levels within 24 hours after injury. Plasma MIF had significant positive correlation with NF-kB translocation of PMNs within 24 hours of incurring trauma (R = 0.668). The presence of anti-MIF antibody in patients' plasma obtained within 24 hours, but not at 72 hours, after injury could significantly partially block the NF-kBp65 translocation and respiratory activity of PMNs in the controls.

CONCLUSIONS

An early increase of plasma MIF associates with NF-kB translocation and respiratory burst in PMNs of severe trauma patients and correlates with higher morbidity. MIF is one of the important factors responsible for early PMN activation and may provide a target of immunomodulation after injury.

Persistent systemic inflammation and atypical enterocolitis in patients with NEMO syndrome

The NEMO syndrome is a primary immunodeficiency with immune and non-immune manifestations. The immune deficiency is heterogeneous showing defects in humoral, innate, and cell-mediated immunity. While the clinical aspects of the immunodeficiency are increasingly well understood, little is known about autoimmune manifestations in NEMO patients. We therefore sought to examine serologic markers of systemic inflammation and intestinal pathology in a kindred of patients with the NEMO syndrome. We observed persistent elevation of erythrocyte sedimentation rates in five patients, and two were symptomatic, with a chronic but atypical enterocolitis. Though pathologic lesions in these two patients were consistent with acute inflammation, sustained clinical improvement was only achieved with systemic and/or topical glucocorticoid therapy. Our data suggest that some patients with the NEMO syndrome exhibit persistent elevation of inflammatory markers similar to systemic autoimmune diseases and may subsequently develop an atypical enterocolitis.