NADPH oxidase activation in neutrophils: Role of the phosphorylation of its subunits

Coronin 1a-mediated F-actin disassembly controls effector function in murine neutrophils

The double-edged role of neutrophils in effective host defense and harmful pathology is an emerging topic in clinical research. Neutrophils release highly potent antimicrobial granule compounds and reactive oxygen species (ROS) that can also be detrimental to the host and promote inflammatory diseases and cancer. Here we show that disassembly of F-actin greatly facilitates ROS production and degranulation in neutrophils. Utilizing neutrophils from Coronin 1a (Coro1a)-deficient mice, our data reveal that the actin-regulatory protein Coro1a controls this spatial F-actin deconstruction and concomitantly forms a signaling complex with Rac-GTPases, thereby promoting activation and translocation of Rac to the membrane during neutrophil activation. This functional activity of Coro1a was critical for neutrophil granule exocytosis and the activation of the NADPH oxidase complex. Consistent with these findings, impaired ROS production in Coro1a-deficient neutrophils was rescued by pharmacological promotion of actin depolymerization or activation of Rac. Together, our findings suggest that the Coro1a/Rac signaling hub acts as a central regulatory element that coordinates actin cytoskeletal reorganization required for the execution of neutrophil effector functions. Since Coro1a is highly conserved between mice and humans and associated with human immunodeficiency, our results are also relevant for human biomedical studies.

Discovery of a novel C2-functionalized chromen-4-one scaffold for the development of p38α MAPK signaling inhibitors to mitigate neutrophilic inflammatory responses

Neutrophil dysregulation is implicated in a spectrum of inflammatory pathologies, suggesting the potential for targeting neutrophilic hyperactivation as a pharmacological strategy to manage inflammatory disorders. Building upon prior research where 2-thiolphenoxychromone derivatives were found to inhibit neutrophilic generation of superoxide anions, this study focused on exploring the structure-activity relationship (SAR) of different C2 bridging moieties and anti-inflammatory effects using bioisosteric replacements and scaffold-hopping approaches. Among various chemotypes, the N-(4-oxo-4H-chromen-2-yl)benzenesulfonamide derivatives emerged as robust inhibitors of both superoxide anion generation and elastase release from fMLF-activated human neutrophils, with IC50 values in the single-digit micromolar range. Leveraging a forward pharmacology approach through computational prediction, compound 15b, a representative within this active molecular class, was discovered to exert these anti-inflammatory functions by blocking the p38α mitogen-activated protein kinase (MAPK) signaling cascade. This responded to a significant reduction in p38α MAPK and its downstream MK2 phosphorylation in activated neutrophils treated with 15b, with no apparent impact on extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and protein kinase B (AKT) phosphorylation levels. Additionally, this molecule exhibited inhibitory potential on intracellular reactive oxygen species (ROS) production, granule exocytosis, and chemotactic responses. Collectively, this study provides a novel skeleton for the development of inhibitors targeting the p38α MAPK pathway to mitigate neutrophilic inflammation.

Investigating neutrophil responses to stimuli: Comparative analysis of reactive species-dependent and independent mechanisms

Neutrophils play a critical role in immune response, using mechanisms as degranulation, phagocytosis, and the release of extracellular DNA together with microbicidal proteins, the so-called neutrophil extracellular traps (NETs), to combat pathogens. Multiple mechanisms might be involved in neutrophil's response to stimuli, but the biochemical characterization of each different pathway is still lacking. In this study, we used superoxide measurements, live-imaging microscopy and high-resolution proteomics to provide a thorough biochemical characterization of the neutrophil's response following activation by two well-known stimuli, namely phorbol-12-myristate-13-acetate (PMA), and ionomycin, a calcium ionophore. Our results demonstrated that although both stimuli induce extracellular DNA release, signals and mediators released by activated cells before this final event were distinct. Thus, PMA-treated neutrophils induce superoxide production, and degranulation of proteins from all granules, especially those derived from secretory vesicles and tertiary granules. On the other hand, ionomycin-treated neutrophils do not stimulate superoxide generation, but induce extensive protein citrullination (also known as arginine deimination), particularly modifying proteins related to actin cytoskeleton organization, nucleus stability, and the NADPH oxidase complex. Interestingly, many of the citrullinated proteins detected in this work were also found to act as autoantigens in autoimmune diseases such as rheumatoid arthritis. These striking differences show neutrophils' response to PMA and ionomycin are two distinct biochemical processes that point towards neutrophils diversification and plasticity responding to the environment. It also provides implications for understanding neutrophil-driven microbial response and potential roles in autoimmune diseases.

The Warburg effect: The hacked mitochondrial-nuclear communication in cancer

Mitochondrial-nuclear communication is vital for maintaining cellular homeostasis. This communication begins with mitochondria sensing environmental cues and transmitting signals to the nucleus through the retrograde cascade, involving metabolic signals such as substrates for epigenetic modifications, ATP and AMP levels, calcium flux, etc. These signals inform the nucleus about the cell's metabolic state, remodel epigenome and regulate gene expression, and modulate mitochondrial function and dynamics through the anterograde feedback cascade to control cell fate and physiology. Disruption of this communication can lead to cellular dysfunction and disease progression, particularly in cancer. The Warburg effect is the metabolic hallmark of cancer, characterized by disruption of mitochondrial respiration and increased lactate generation from glycolysis. This metabolic reprogramming rewires retrograde signaling, leading to epigenetic changes and dedifferentiation, further reprogramming mitochondrial function and promoting carcinogenesis. Understanding these processes and their link to tumorigenesis is crucial for uncovering tumorigenesis mechanisms. Therapeutic strategies targeting these disrupted pathways, including metabolic and epigenetic components, provide promising avenues for cancer treatment.

NQO1-Responsive Prodrug for in Cellulo Release of Cytochalasin B as Cancer Cell-Targeted Migrastatic

Migrastatic drugs targeting cell motility and suppressing invasiveness of solid tumors, have the potential to bring about a paradigm shift in the treatment of solid cancer. Cytochalasin B (CB) is a potent migrastatic compound, but its clinical use is limited by poor selectivity. Here, a NQO1-responsive prodrug, BQTML-CB is developed, synthesized in three steps from cytochalasin B derived from Preussia similis G22. BQTML-CB is selectively activated in NQO1-positive cancer cells, releasing active CB. In vitro, BQTML-CB significantly inhibits proliferation and migration in NQO1-positive U-2OS cells, causing actin disruption and cytokinesis abnormalities, while sparing NQO1-negative B16-F1 cells. The prodrug shows reduced effects on human neutrophils, indicating reduced immunosuppressive activity of BQTML-CB compared to CB. Co-culture studies reveal a beneficial bystander effect, as cleaved CB diffused into adjacent NQO1-deficient cells. These findings support BQTML-CB as a cancer-targeted prodrug with selective antiproliferative and migrastatic properties, highlighting the potential of C7-OH-modified cytochalasans in cancer therapy.

The Role of NADPH Oxidase 2 in Leukocytes

NADPH oxidase (NOX) family members are major resources of intracellular reactive oxygen species (ROS). In the immune system, ROS derived from phagocytic NOX (NOX2) participate in both pathogen clearance and signaling transduction. The role of NOX2 in neutrophils and macrophages has been well studied as mutations in NOX2 subunits cause chronic granulomas disease (CGD). NOX2 is expressed across a wide range of immune cells and recent reports have demonstrated that NOX2-derived ROS play important roles in other immune cells during an immune response. In this review, we summarize current knowledge of functions of NADPH oxidase 2 in each subset of leukocytes, as well as associations of NOX2 deficiency with diseases associated specifically with autoimmunity and immune deficiency. We also discuss important knowledge gaps as well as potential future directions for NOX2 research.

Candida albicans aspartyl protease (Sap6) inhibits neutrophil function via a "Trojan horse" mechanism

Candida albicans, a prevalent fungal pathogen, employs aspartyl proteases such as Sap6 to evade immune defenses, challenging our understanding of host‒pathogen interactions. This research examined the impact of Sap6 on neutrophil responses, which are crucial for innate immunity. Employing flow cytometry and fluorescence microscopy, we explored how Sap6 affects neutrophil functions, particularly by focusing on reactive oxygen species (ROS) production, neutrophil extracellular traps release (NETosis), and apoptosis. Our findings revealed Sap6's unique ability to bind and internalize in neutrophils, significantly attenuating ROS production through proteolytic damage to NADPH oxidase, resulting in blocking the ROS-dependent NETosis pathway. This disruption in neutrophil functions by Sap6 suggested the presence of a 'Trojan horse' mechanism by C. albicans. This mechanism reveals a sophisticated immune evasion strategy, shedding light on fungal pathogenicity and host immune interactions. Understanding fungal proteases in immune modulation could inspire new therapeutic approaches for fungal infections.

Bacterial small molecule metabolites implicated in gastrointestinal cancer development

Numerous associations have been identified between cancer and the composition and function of the human microbiome. As cancer remains the second leading global cause of mortality, investigating the carcinogenic contributions of microbiome members could advance our understanding of cancer risk and support potential therapeutic interventions. Although fluctuations in bacterial species have been associated with cancer progression, studying their small molecule metabolites offers one avenue to establish support for causal relationships and the molecular mechanisms governing host-microorganism interactions. In this Review, we explore the expanding repertoire of small molecule metabolites and their mechanisms implicated in the risk of developing gastrointestinal cancers.

The association between NADPH oxidase (NOX) polymorphisms with immunohistochemistry and survival in diffuse large B cell lymphoma patients

The purpose of this study was to comprehensively analyze the prediction role of NADPH oxidase (NOX)-related polymorphisms (NCF4: rs1883112, CYBA: rs4673, RAC2: rs13058338) and immunohistochemical indices on survival in diffuse large B-cell lymphoma (DLBCL).The impact of NOX polymorphisms were evaluated in 335 DLBCL patients treated with R (rituximab)-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisone) from Harbin Medical University Cancer Hospital. We also collected information on their immunohistochemical expression and clinical outcomes.Among the patients treated with R-CHOP therapy, the patients with CyclinD1 (+) had significantly shorter progression-free survival (PFS) (p = 0.001) and event-free survival (EFS) (p < 0.001) than CyclinD1 (-) patients. Among patients received CHOP therapy, PFS was significantly longer in CD20 (+) patients (p = 0.011) than in CD20(-) patients. Among the patients treated with R-CHOP therapy, the PFS (p = 0.020) and EFS (p < 0.001) of patients with NCF4 rs1883112 AA/AG genotype were significantly longer than the patients with GG genotype. Patients treated with R-CHOP therapy and with RAC2 rs13058338 AA/AT genotype were more likely to have grade III or higher myelosuppression compared to patients with TT genotype (p = 0.027). Patients treated with CHOP therapy and with RAC2 rs13058338 AA/AT genotype were more likely to have grade III or higher systemic adverse events (p = 0.029). Cox regression analysis showed that NCF4 rs1883112 GG genotype and CyclinD1 (+) were the factors contributing to the poor outcomes in DLBCL patients treated with R-CHOP therapy.In conclusion, the results suggested that the NCF4 rs1883112 G allele may be a poor prognostic biomarker, especially for the DLBCL patients with CD3(-), CD5 (-), CD10 (-), Bcl-2 (+), Bcl-6 (+) or Ki-67(%) < 80%.

Modulating Phosphorylation by Proximity-Inducing Modalities for Cancer Therapy

Abnormal phosphorylation of proteins can lead to various diseases, particularly cancer. Therefore, the development of small molecules for precise regulation of protein phosphorylation holds great potential for drug design. While the traditional kinase/phosphatase small-molecule modulators have shown some success, achieving precise phosphorylation regulation has proven to be challenging. The emergence of heterobifunctional molecules, such as phosphorylation-inducing chimeric small molecules (PHICSs) and phosphatase recruiting chimeras (PHORCs), with proximity-inducing modalities is expected to lead to a breakthrough by specifically recruiting kinase or phosphatase to the protein of interest. Herein, we summarize the drug targets with aberrant phosphorylation in cancer and underscore the potential of correcting phosphorylation in cancer therapy. Through reported cases of heterobifunctional molecules targeting phosphorylation regulation, we highlight the current design strategies and features of these molecules. We also provide a systematic elaboration of the link between aberrantly phosphorylated targets and cancer as well as the existing challenges and future research directions for developing heterobifunctional molecular drugs for phosphorylation regulation.

Standardization of the use of opsonized zymosan as stimulus in the 1,2,3-dihydrorhodamine technique for the assessment of neutrophil respiratory burst

Introduction

Chronic granulomatous disease is a defect in phagocytosis due to deficiency of gp91phox, p22phox, p47phox, p40phox, and p67phox (classic form of the disease). Recently, EROS and p40phox deficiency were described as responsible for the non-classical form of the disease. The 1,2,3-dihydrorhodamine oxidation technique, with phorbol-12-myristate-13-acetate as a stimulus, is performed to diagnose the classic chronic granulomatous disease. However, oxidation mediated by EROS and p40phox requires stimuli such as zymosan, Escherichia coli, or Staphylococcus aureus.

Objective

To optimize the 1,2,3-dihydrorhodamine technique using zymosan to assess neutrophil respiratory burst and detect the non-classical chronic granulomatous disease.

Materials and method

Blood was obtained from five healthy subjects after the signature of the informed consent. The 1,2,3-dihydrorhodamine technique was performed with phorbol-12-myristate-13-acetate as control and different quantities of opsonized zymosan (150, 100, 50, 20, and 10 μg). We obtained through flow cytometry the mean fluorescence intensity of rhodamine 1,2,3 oxidated in the neutrophil population and calculated the oxidation index. The Kolmogorov-Smirnov test, ANOVA, and Tukey’s post-hoc analysis were used. We considered a p value ≤ 0.05 as statistically significant.

Results

The phorbol-12-myristate-13-acetate increased the rhodamine 1,2,3 mean fluorescence intensity in healthy subjects. Among the different zymosan conditions tested, we selected 50 μg as the optimal and reproducible amount in all controls according to the statistical analysis and cytometric findings.

Conclusions

We present the optimization of the 1,2,3-dihydrorhodamine technique using zymosan. We propose its implementation in clinical diagnostic laboratories to expand the diagnosis of chronic granulomatous disease.

Complement component 5a receptor 1 and leukotriene B4 receptor 1 regulate neutrophil extracellular trap (NET) formation through Rap1a/B-Raf/ERK signaling pathway and their deficiency in term low birth weight newborns leads to deficient NETosis

BACKGROUND

Neutrophil extracellular traps (NETs) being one of the predominant activities of neutrophils has become its key defense mechanism owing to its extensive role in inflammation and infection. However, the mechanisms regulating NET formation or NETosis still remains to be better understood. Our earlier whole genome transcriptomic data revealed two G-protein couple receptors (GPCRs) - complement component 5a receptor 1 (C5aR1) and leukotriene B4 receptor 1 (LTB4R1) were downregulated in term low birth weight (tLBW) newborns with deficient NET formation abilities. Neutrophils employ C5aR1 and LTB4R1 for mediating their immune responses, inflammation and antimicrobial activity. Hence, this study was aimed to explore the role of two GPCRs, C5aR1 and LTB4R1 including their downstream signaling molecules in NETs induction and regulation.

METHODS

The validation of the transcriptomic data for C5aR1 and LTB4R1 was done using quantitative real time PCR. Pharmacological inhibition of C5aR1 and LTB4R1 using W-54011 and LY223982 on neutrophils of adults and newborns' was done to study their impact on NETosis. Extracellular DNA release, Reactive oxygen species (ROS) generation, expression of NET proteins, and signaling molecules downstream to C5aR1 and LTB4R1 were quantified using plate reader based assay, immunofluorescence, and western blotting. Myeloperoxidase (MPO)-DNA quantified by flow cytometry. Knockdown studies using siRNA against C5aR1 and LTB4R1 were done in HL-60 cells derived surrogate neutrophils and expression of downstream molecules of the two GPCRs, C5aR1 and LTB4R1 signaling axis along with NET proteins was quantified by western blotting.

RESULTS

The expression of C5aR1 and LTB4R1, extracellular DNA, ROS and NET associated proteins (NE, CitH3, PAD4 and MPO) was notably increased upon NET induction in healthy adults and normal birth weight (NBW) newborns' neutrophils. Pharmacological inhibition of these two GPCRs led to substantial reduction in NETosis, extracellular DNA, ROS generation, and expression of NET associated proteins like CitH3, NE, PAD4, MPO along with downstream signaling molecules Rap1a, B-Raf and pERK. Our observations suggest a precise role of C5aR1 and LTB4R1 on induction of NETs via Rap1a/B-Raf/ERK signaling axis.

CONCLUSION

The C5aR1 and LTB4R1 signaling via Rap1a/B-Raf/ERK axis acts as a signal-relay mechanism to regulate NET formation in neutrophils. Further, C5aR1 and LTB4R1 signaling cascade along with NET-associated proteins are remarkably downregulated in tLBW newborns' neutrophils leading to impaired NETosis in them. Therefore, C5aR1 and LTB4R1 and their signaling molecules could provide an effective therapeutic target for compromised NETosis like tLBW newborns.

Opuntia ficus-indica cladodes extract inhibits human neutrophil pro-inflammatory functions and protects rats from acetic acid-induced ulcerative colitis

The increased production of reactive oxygen species (ROS) by human neutrophils can lead to oxidative imbalances and several diseases, such as inflammatory bowel disease (IBD). Opuntia ficus-indica (O. ficus-indica) is rich in bioactive substances with anti-inflammatory properties. This study aimed to identify the bioactive compounds present in aqueous cladodes extract (ACE) of O. ficus-indica using high-performance liquid chromatography (HPLC) and to test its effects on human neutrophil inflammatory functions and on ulcerative colitis (UC) induced by acetic acid (Aa) in rats. ROS production and degranulation by neutrophils were assessed by luminol-amplified chemiluminescence, enzymatic techniques, and western blotting. In vivo, the experiment involved seven groups of rats: a negative control group (NaCl), the acetic acid group (Aa), and groups treated with oral sulfasalazine (150 mg/kg) or various doses of ACE for 7 days. Colonic lesions were induced by an intra-rectal Aa injection, and inflammation was assessed. HPLC analysis identified gallic acid, catechin, caffeic acid, and ferulic acid as major compounds in ACE. In vitro, ACE inhibited neutrophil ROS production, including superoxide anion produced by NADPH oxidase, and significantly reduced myeloperoxidase activity and neutrophil degranulation. In vivo, ACE protected rats from Aa-induced histopathological damage of the colonic mucosa, significantly increased catalase, superoxide dismutase and reduced glutathione levels, and significantly suppressed the increases of plasma cytokines (TNF-α and IL-1β) observed in the Aa group. In conclusion, O. ficus-indica ACE has significant anti-inflammatory properties by restoring oxidative balance, indicating that it could be a potential source of therapeutic agents for inflammatory diseases, particularly UC.

NCF-1 plays a pivotal role in the survival of adenocarcinoma cells of pancreatic and gastric origins

Reactive oxygen species (ROS) play a pivotal biological role in cells, with ROS function differing depending on cellular conditions and the extracellular environment. Notably, ROS act as cytotoxic factors to eliminate infectious pathogens or promote cell death under cellular stress, while also facilitating cell growth (via ROS-sensing pathways) by modifying gene expression. Among ROS-related genes, neutrophil cytosolic factor-1 (NCF-1; p47phox) was identified as a ROS generator in neutrophils. This product is a subunit of a cytosolic NADPH oxidase complex activated in response to pathogens such as bacteria and viruses. NCF-1 has been examined primarily in terms of ROS-production pathways in macrophages and neutrophils; however, the expression of this protein and its biological role in cancer cells remain unclear. Here, we report expression of NCF-1 in pancreatic and gastric cancers, and demonstrate its biological significance in these tumor cells. Abundant expression of NCF-1 was observed in pancreatic adenocarcinoma (PDAC) lines and in patient tissues, as well as in gastric adenocarcinomas. Accumulation of the protein was also detected in the invasive/metastatic foci of these tumors. Unexpectedly, BxPC-3 underwent apoptotic cell death when transfected with a small interfering RNA (siRNA) specific to NCF-1, whereas the cells treated with a control siRNA proliferated in a time-dependent manner. A similar phenomenon was observed in HSC-58, a poorly differentiated gastric adenocarcinoma line. Consequently, the tumor cells highly expressing NCF-1 obtained coincident accumulation of ROS and reduced glutathione (GSH) with expression of glutathione peroxidase 4 (GPX4), a quencher involved in ferroptosis. Unlike the conventional role of ROS as a representative cytotoxic factor, these findings suggest that NCF-1-mediated ROS generation may be required for expansive growth of PDAC and gastric cancers.

Signaling by neutrophil G protein-coupled receptors that regulate the release of superoxide anions

In human peripheral blood, the neutrophil granulocytes (neutrophils) are the most abundant white blood cells. These professional phagocytes are rapidly recruited from the bloodstream to inflamed tissues by chemotactic factors that signal danger. Neutrophils, which express many receptors that are members of the large family of G protein-coupled receptors (GPCRs), are critical for the elimination of pathogens and inflammatory insults, as well as for the resolution of inflammation leading to tissue repair. Danger signaling molecular patterns such as the N-formylated peptides that are formed during bacterial and mitochondrial protein synthesis and recognized by formyl peptide receptors (FPRs) and free fatty acids recognized by free fatty acid receptors (FFARs) regulate neutrophil functions. Short peptides and short-chain fatty acids activate FPR1 and FFA2R, respectively, while longer peptides and fatty acids activate FPR2 and GPR84, respectively. The activation profiles of these receptors include the release of reactive oxygen species (ROS) generated by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Activation of the oxidase and the production of ROS are processes that are regulated by proinflammatory mediators, including tumor necrosis factor α and granulocyte/macrophage colony-stimulating factor. The receptors have signaling and functional similarities, although there are also important differences, not only between the two closely related neutrophil FPRs, but also between the FPRs and the FFARs. In neutrophils, these receptors never walk alone, and additional mechanistic insights into the regulation of the GPCRs and the novel regulatory mechanisms underlying the activation of NADPH oxidase advance our understanding of the role of receptor transactivation in the regulation of inflammatory reactions.

Insights into Alkaline Phosphatase Anti-Inflammatory Mechanisms

BACKGROUND

The endogenous ecto-enzyme and exogenously administered alkaline phosphatase (ALP) have been evidenced to significantly attenuate inflammatory conditions, including Toll-like receptor 4 (TLR4)-related signaling and cytokine overexpression, barrier tissue dysfunction and oxidative stress, and metabolic syndrome and insulin resistance, in experimental models of colitis, liver failure, and renal and cardiac ischemia-reperfusion injury. This suggests multiple mechanisms of ALP anti-inflammatory action that remain to be fully elucidated.

METHODS

Recent studies have contributed to a deeper comprehension of the role played by ALP in immune metabolism. This review outlines the established effects of ALP on lipopolysaccharide (LPS)-induced inflammation, including the neutralization of LPS and the modulation of purinergic signaling.

RESULTS

The additional mechanisms of anti-inflammatory activity of ALP observed in different pathologies are proposed.

CONCLUSIONS

The anti-inflammatory pathways of ALP may include a scavenger receptor (CD36)-mediated activation of β-oxidation and oxidative phosphorylation, caveolin-dependent endocytosis, and selective autophagy-dependent degradation.

Evaluation of Bioactive Compounds, Antioxidant Capacity, and Anti-Inflammatory Effects of Lipophilic and Hydrophilic Extracts of the Pericarp of Passiflora tripartita var. mollissima at Two Stages of Ripening

Chronic disease inflammation requires safe complementary treatments. The pericarp of Passiflora tripartita var. mollissima (PTM) contains potential anti-inflammatory metabolites. This study aimed to evaluate the bioactive components, antioxidant capacity, and anti-inflammatory effects of PTM extracts at two ripening stages. The bioactive compounds in the hydrophilic and lipophilic extracts of mature and green pericarps were identified by GC-MS and UV-VIS, while the antioxidant capacity was measured by free radical reduction. Anti-inflammatory effects were tested using a rat paw edema model with carrageenan-induced edema, indomethacin, or PTM extracts (100, 250, and 500 mg/kg). The effect of mature hydrophilic extract was further evaluated in an air pouch model, where rats received the placebo, carrageenan, indomethacin, or the extract (500 and 1000 mg/kg). Leukocytes, cytokines, and markers of oxidative stress were evaluated. The results showed the presence of organic compounds, total phenols, and flavonoids. The mature hydrophilic extract exhibited the highest antioxidant activity. At 500 mg/kg, it reduced edema, leukocyte migration, and levels of IL-1β, IL-6, and TNF-α while managing oxidative stress and preventing histological damage. In conclusion, PTM contains bioactive compounds with potential pharmacological properties. The hydrophilic extract of the mature pericarp, at a dose of 500 mg/kg, exhibits an enhanced antioxidant and anti-inflammatory effect.

Leucine restriction ameliorates Fusobacterium nucleatum-driven malignant progression and radioresistance in nasopharyngeal carcinoma

Radiotherapy resistance is the main cause of treatment failure among patients with nasopharyngeal carcinoma (NPC). Recently, increasing evidence has linked the presence of intratumoral Fusobacterium nucleatum (Fn) with the malignant progression and therapeutic resistance of multiple tumor types, but its influence on NPC has remained largely unknown. We found that Fn is prevalent in the tumor tissue of patients with NPC and is associated with radioresistance. Fn invaded and proliferated inside NPC cells and aggravated tumor progression. Mechanistically, Fn slowed mitochondrial dysfunction by promoting mitochondrial fusion and decreasing ROS generation, preventing radiation-induced oxidative damage. Fn inhibited PANoptosis by the SLC7A5/leucine-mTORC1 axis during irradiation stress, thus promoting radioresistance. Treatment with the mitochondria-targeted antibiotics or dietary restriction of leucine reduced intratumoral Fn load, resensitizing tumors to radiotherapy in vivo. These findings demonstrate that Fn has the potential to be a predictive marker for radioresistance and to help guide individualized treatment for patients with NPC.

Infected wound repair correlates with collagen I induction and NOX2 activation by cold atmospheric plasma

Cold atmospheric plasma (CAP) is a promising complement to tissue repair and regenerative medicine approaches. CAP has therapeutic potential in infected cutaneous wounds by mechanisms which remain enigmatic. Here, CAP is shown to activate phagocyte NADPH oxidase complex NOX2. CAP induced increased intracellular reactive oxygen species, alleviated by NOX2 inhibitors. Genetic and pharmacological inhibitions of NOX2 in macrophages and bioengineered skin infected with Staphylococcus aureus and treated with CAP reduced intracellular oxidants and increased bacterial survival. CAP triggered Rac activation and phosphorylation of p40phox and p47phox required for NOX2 assembly and activity. Furthermore, CAP induced collagen I expression by fibroblasts. Infection and healing kinetics showed that murine skin wounds infected with S. aureus and treated with CAP are characterized by decreased bacterial burden, increased length of neoepidermis and extracellular matrix formation. Collectively, our findings identify mechanisms triggered by CAP that subdue infection and result in enhanced repair following skin injury.

The peptidyl-prolyl isomerase Pin1 controls GM-CSF-induced priming of NADPH oxidase in human neutrophils and priming at inflammatory sites

The production of superoxide anions and other reactive oxygen species (ROS) by neutrophils is necessary for host defense against microbes. However, excessive ROS production can induce cell damage that participates in the inflammatory response. Superoxide anions are produced by the phagocyte NADPH oxidase, a multicomponent enzyme system consisting of two transmembrane proteins (gp91phox/NOX2 and p22phox) and four soluble cytosolic proteins (p40phox, p47phox, p67phox and the small G proteins Rac1/2). Stimulation of neutrophils by various agonists, such as the bacterial peptide formyl-Met-Leu-Phe (fMLF), induces NADPH oxidase activation and superoxide production, a process that is enhanced by the pro-inflammatory cytokines such as GM-CSF. The pathways involved in this GM-CSF-induced up-regulation or priming are not fully understood. Here we show that GM-CSF induces the activation of the prolyl cis/trans isomerase Pin1 in human neutrophils. Juglone and PiB, two selective Pin1 inhibitors, were able to block GM-CSF-induced priming of ROS production by human neutrophils. Interestingly, GM-CSF induced Pin1 binding to phosphorylated p47phox at Ser345. Neutrophils isolated from synovial fluid of patients with rheumatoid arthritis are known to be primed. Here we show that Pin1 activity was also increased in these neutrophils and that Pin1 inhibitors effectively inhibited ROS hyperproduction by the same cells. These results suggest that the prolyl cis/trans isomerase Pin1 may control GM-CSF-induced priming of ROS production by neutrophils and priming of neutrophils in synovial fluid of rheumatoid arthritis patients. Pharmacological targeting of Pin1 may be a valuable approach to the treatment of inflammation.

The emerging role of neutrophil extracellular traps in ulcerative colitis

Ulcerative colitis (UC) is characterized by chronic non-recessive inflammation of the intestinal mucosa involving both innate and adaptive immune responses. Currently, new targeted therapies are urgently needed for UC, and neutrophil extracellular traps (NETs) are new therapeutic options. NETs are DNA-based networks released from neutrophils into the extracellular space after stimulation, in which a variety of granule proteins, proteolytic enzymes, antibacterial peptides, histones, and other network structures are embedded. With the deepening of the studies on NETs, their regulatory role in the development of autoimmune and autoinflammatory diseases has received extensive attention in recent years. Increasing evidence indicates that excess NETs exacerbate the inflammatory response in UC, disrupting the structure and function of the intestinal mucosal barrier and increasing the risk of thrombosis. Although NETs are usually assigned a deleterious role in promoting the pathological process of UC, they also appear to have a protective role in some models. Despite such progress, comprehensive reviews describing the therapeutic promise of NETs in UC remain limited. In this review, we discuss the latest evidence for the formation and degradation of NETs, focusing on their double-edged role in UC. Finally, the potential implications of NETs as therapeutic targets for UC will be discussed. This review aims to provide novel insights into the pathogenesis and therapeutic options for UC.

Neutrophil extracellular traps in cancer

Neutrophil extracellular traps (NETs), which consist of chromatin DNA studded with granule proteins, are released by neutrophils in response to both infectious and sterile inflammation. Beyond the canonical role in defense against pathogens, the extrusion of NETs also contributes to the initiation, metastasis, and therapeutic response of malignant diseases. Recently, NETs have been implicated in the development and therapeutic responses of various types of tumors. Although extensive work regarding inflammation in tumors has been reported, a comprehensive summary of how these web-like extracellular structures initiate and propagate tumor progression under the specific microenvironment is lacking. In this review, we demonstrate the initiators and related signaling pathways that trigger NETs formation in cancers. Additionally, this review will outline the current molecular mechanisms and regulatory networks of NETs during dormant cancer cells awakening, circulating tumor cells (CTCs) extravasation, and metastatic recurrence of cancer. This is followed by a perspective on the current and potential clinical potential of NETs as therapeutic targets in the treatment of both local and metastatic disease, including the improvement of the efficacy of existing therapies.

NETosis of psoriasis: a critical step in amplifying the inflammatory response

NETosis, a regulated form of neutrophil death, is crucial for host defense against pathogens. However, the release of neutrophil extracellular traps (NETs) during NETosis can have detrimental effects on surrounding tissues and contribute to the pro-inflammatory response, in addition to their role in controlling microbes. Although it is well-established that the IL-23-Th17 axis plays a key role in the pathogenesis of psoriasis, emerging evidence suggests that psoriasis, as an autoinflammatory disease, is also associated with NETosis. The purpose of this review is to provide a comprehensive understanding of the mechanisms underlying NETosis in psoriasis. It will cover topics such as the formation of NETs, immune cells involved in NETosis, and potential biomarkers as prognostic/predicting factors in psoriasis. By analyzing the intricate relationship between NETosis and psoriasis, this review also aims to identify novel possibilities targeting NETosis for the treatment of psoriasis.

Drug repurposing of cyclin-dependent kinase inhibitors for neutrophilic acute respiratory distress syndrome and psoriasis

BACKGROUND

Neutrophilic inflammation, characterized by dysregulated neutrophil activation, triggers a variety of inflammatory responses such as chemotactic infiltration, oxidative bursts, degranulation, neutrophil extracellular traps (NETs) formation, and delayed turnover. This type of inflammation is pivotal in the pathogenesis of acute respiratory distress syndrome (ARDS) and psoriasis. Despite current treatments, managing neutrophil-associated inflammatory symptoms remains a significant challenge.

AIM OF REVIEW

This review emphasizes the role of cyclin-dependent kinases (CDKs) in neutrophil activation and inflammation. It aims to highlight the therapeutic potential of repurposing CDK inhibitors to manage neutrophilic inflammation, particularly in ARDS and psoriasis. Additionally, it discusses the necessary precautions for the clinical application of these inhibitors due to potential off-target effects and the need for dose optimization.

KEY SCIENTIFIC CONCEPTS OF REVIEW

CDKs regulate key neutrophilic functions, including chemotactic responses, degranulation, NET formation, and apoptosis. Repurposing CDK inhibitors, originally developed for cancer treatment, shows promise in controlling neutrophilic inflammation. Clinical anticancer drugs, palbociclib and ribociclib, have demonstrated efficacy in treating neutrophilic ARDS and psoriasis by targeting off-label pathways, phosphoinositide 3-kinase (PI3K) and phosphodiesterase 4 (PDE4), respectively. While CDK inhibitors offer promising therapeutic benefits, their clinical repurposing requires careful consideration of off-target effects and dose optimization. Further exploration and clinical trials are necessary to ensure their safety and efficacy in treating inflammatory conditions.

Diagnosis of Chronic Granulomatous Disease: Strengths and Challenges in the Genomic Era

Chronic granulomatous disease (CGD) is a group of rare primary inborn errors of immunity characterised by a defect in the phagocyte respiratory burst, which leads to severe and life-threatening infective and inflammatory complications. Despite recent advances in our understanding of the genetic and molecular pathophysiology of X-linked and autosomal recessive CGD, and growth in the availability of functional and genetic testing, there remain significant barriers to early and accurate diagnosis. In the current review, we provide an up-to-date summary of CGD pathophysiology, underpinning current methods of diagnostic testing for CGD and closely related disorders. We present an overview of the benefits of early diagnosis and when to suspect and test for CGD. We discuss current and historical methods for functional testing of NADPH oxidase activity, as well as assays for measuring protein expression of NADPH oxidase subunits. Lastly, we focus on genetic and genomic methods employed to diagnose CGD, including gene-targeted panels, comprehensive genomic testing and ancillary methods. Throughout, we highlight general limitations of testing, and caveats specific to interpretation of results in the context of CGD and related disorders, and provide an outlook for newborn screening and the future.

High salt intake and HIV infection on endothelial glycocalyx shedding in salt-sensitive hypertension

The endothelial glycocalyx is closely associated with various physiological and pathophysiological events. Significant modification of the endothelial glycocalyx is an early process in the pathogenesis of cardiovascular disease. High dietary salt and HIV infection damages the endothelial glycocalyx causing endothelial dysfunction and increasing the risk for salt-sensitive hypertension and cardiovascular disease. The two factors, HIV infection and dietary salt are critical independent predictors of hypertension and cardiovascular disease and often synergize to exacerbate and accelerate disease pathogenesis. Salt-sensitive hypertension is more common among people living with HIV and is associated with risk for cardiovascular disease, stroke, heart attack and even death. However, the underlying mechanisms linking endothelial glycocalyx damage to dietary salt and HIV infection are lacking. Yet, both HIV infection/treatment and dietary salt are closely linked to endothelial glycocalyx damage and development of salt-sensitive hypertension. Moreover, the majority of individuals globally, consume more salt than is recommended and the burden of HIV especially in sub-Sahara Africa is disproportionately high. In this review, we have discussed the missing link between high salt and endothelial glycocalyx shedding in the pathogenesis of salt-sensitive hypertension. We have further elaborated the role played by HIV infection and treatment in modifying endothelial glycocalyx integrity to contribute to the development of hypertension and cardiovascular disease.

Clinical and molecular significance of flow cytometric analysis for reactive oxygen species production and residual p67phox expression in p67phox-deficient chronic granulomatous disease

Chronic granulomatous disease (CGD) is a primary immunodeficiency disease caused by molecular defects in nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. p67phox-CGD is an autosomal recessive CGD, which is caused by a defect in the cytosolic components of NADPH oxidase, p67phox, encoded by NCF2. We previously established a flow cytometric analysis for p67phox expression, which allows accurate assessment of residual protein expression in p67phox-CGD. We evaluated the correlation between oxidase function and p67phox expression, and assessed the relevancy to genotypes and clinical phenotypes in 11 patients with p67phox-CGD. Reactive oxygen species (ROS) production by granulocytes was evaluated using dihydrorhodamine-1,2,3 (DHR) assays. p67phox expression was evaluated in the monocyte population. DHR activity and p67phox expression were significantly correlated (r = 0.718, p < 0.0162). Additionally, DHR activity and p67phox expression were significantly higher in patients carrying one missense variant in combination with one nonsense or frameshift variant in the NCF2 gene than in patients with only null variants. The available clinical parameters of our patients (i.e., age at disease onset, number of infectious episodes, and each infection complication) were not linked with DHR activity or p67phox expression levels. In summary, our flow cytometric analysis revealed a significant correlation between residual ROS production and p67phox expression. More deleterious NCF2 genotypes were associated with lower levels of DHR activity and p67phox expression. DHR assays and protein expression analysis by using flow cytometry may be relevant strategies for predicting the genotypes of p67phox-CGD.

PTP1B phosphatase dampens iPSC-derived neutrophil motility and antimicrobial function

Neutrophils are rapidly recruited to sites of infection and are critical for pathogen clearance. Therapeutic use of primary neutrophils has been limited, as they have a short lifespan and are not amenable to genetic manipulation. Human induced pluripotent stem cells (iPSCs) can provide a robust source of neutrophils for infusion and are genetically tractable. However, current work has indicated that dampened intracellular signaling limits iPSC-derived neutrophil (iNeutrophil) cellular activation and antimicrobial response. Here, we show that protein tyrosine phosphatase 1B (PTP1B) inhibits intracellular signaling and dampens iNeutrophil effector function. Deletion of the PTP1B phosphatase increased PI3K and ERK signaling and was associated with increased F-actin polymerization, cell migration, and phagocytosis. In contrast, other effector functions like NETosis and reactive oxygen species production were reduced. PTP1B-deficient neutrophils were more responsive to Aspergillus fumigatus and displayed rapid recruitment and control of hyphal growth. Accordingly, depletion of PTP1B increased production of inflammatory factors including the neutrophil chemokine interleukin-8. Taken together, these findings suggest that PTP1B limits iNeutrophil motility and antimicrobial function.

Phagosomal granulocytic ROS in septic patients induce the bacterial SOS response

Septic patients with worst clinical prognosis have increased circulating immature granulocytes (IG), displaying limited phagocytosis and reactive oxygen species (ROS) production. Here, we developed an ex vivo model of incubation of human granulocytes, from septic patients or healthy donors, with Escherichia coli. We showed that the ROS production in Sepsis-IG is lower due to decreased activation and protein expression of the NADPH oxidase complex. We also demonstrated that the low level of ROS production and lower phagocytosis of IG in sepsis induce the bacterial SOS response, leading to the expression of the SOS-regulated quinolone resistance gene qnrB2. Without antimicrobial pressure, the sepsis immune response alone may promote antibiotic resistance expression.

Necroptosis and immune infiltration in hypertrophic cardiomyopathy: novel insights from bioinformatics analyses

Background

Hypertrophic Cardiomyopathy (HCM), a widespread genetic heart disorder, is largely associated with sudden cardiac fatality. Necroptosis, an emerging type of programmed cell death, plays a fundamental role in several cardiovascular diseases.

Aim

This research utilized bioinformatics analysis to investigate necroptosis's implication in HCM.

Methods

The study retrieved RNA sequencing datasets GSE130036 and GSE141910 from the Gene Expression Omnibus (GEO) database. It detected necroptosis-linked differentially expressed genes (NRDEGs) by reviewing both the gene set for necroptosis and the differently expressed genes (DEGs). The enriched signaling pathway of HCM was assessed using GSEA, while common DEGs were studied through Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Concurrently, the Protein-Protein Interaction network (PPI) proved useful for identifying central genes. CIBERSORT facilitated evaluating the correlation between distinct immune cell-type prevalence and NRDEGs by analyzing immune infiltration patterns. Lastly, GSE141910 dataset validated the expression ranks of NRDEGs and immune-cell penetration.

Results

The investigation disclosed significant enrichment and activation of the necroptosis pathway in HCM specimens. Seventeen diverse genes, including CYBB, BCL2, and JAK2 among others, were identified in the process. PPI network scrutiny classified nine of these genes as central genes. Results from GO and KEGG enrichment analyses showed substantial connections of these genes to pathways pertaining to the HIF-1 signaling track, necroptosis, and NOD-like receptor signaling process. Moreover, an imbalance in M2 macrophage cells in HCM samples was observed. Finally, CYBB, BCL2, and JAK2 emerged as vital genes and were validated using the GSE141910 dataset.

Conclusion

These results indicate necroptosis as a probable underlying factor in HCM, with immune cell infiltration playing a part. Additionally, CYBB, BCL2, JAK2 could act as potential biomarkers for recognizing HCM. This information forms crucial insights into the basic mechanisms of HCM and could enhance its diagnosis and management.

The role of neutrophils and neutrophil extracellular traps (NETs) in stages, outcomes and pregnancy complications

Neutrophils are the main components of innate immunity to eliminate infectious pathogens. Neutrophils play a role in several stages of the reproductive cycle, and their presence in the female reproductive system is highly regulated, so their function may change during pregnancy. Emerging evidence suggests that neutrophils are important at all stages of pregnancy, from implantation, placentation, and connective tissue regeneration to birth, as well as birth itself. Neutrophil extracellular traps (NETs) are defined as extracellular strands of unfolded DNA together with histone complexes and neutrophil granule proteins. NET formation is a new mechanism of these cells for their defense function. These strands containing DNA and antimicrobial peptides were initially recognized as one of the defense mechanisms of neutrophils, but later it was explained that they are involved in a variety of non-infectious diseases. Since the source of inflammation and tissue damage is the irregular activity of neutrophils, it is not surprising that NETosis are associated with a number of inflammatory conditions and diseases. The overexpression of NET components or non-principled NET clearance is associated with the risk of production and activation of autoantibodies, which results in participation in autoinflammatory and autoimmune disorders (SLE, RA), fibrosis, sepsis and other disorders such as vascular diseases, for example, thrombosis and atherosclerosis. Recent published articles have shown the role of neutrophils and extracellular traps (NETs) in pregnancy, childbirth and pregnancy-related diseases. The aim of this study was to identify and investigate the role of neutrophils and neutrophil extracellular traps (NETs) in the stages of pregnancy, as well as the complications caused by these cells.

Expression and secretion of galectin-12 in the context of neutrophilic differentiation of human promyeloblastic HL-60 cells

Galectin-12 is a tissue-specific galectin that has been largely defined by its role in the regulation of adipocyte differentiation and lipogenesis. This study aimed to evaluate the role of galectin-12 in the differentiation and polarization of neutrophils within a model of acute myeloid leukemia HL-60 cells. All-trans retinoic acid and dimethyl sulfoxide were used to induce differentiation of HL-60 cells which led to the generation of two phenotypes of neutrophil-like cells with opposite changes in galectin-12 gene (LGALS12) expression and different functional responses to N-formyl- l-methionyl- l-leucyl- l-phenylalanine. These phenotypes showed significant differences of differentially expressed genes on a global scale based on bioinformatics analysis of available Gene Expression Omnibus (GEO) data sets. We also demonstrated that HL-60 cells could secrete and accumulate galectin-12 in cell culture medium under normal growth conditions. This secretion was found to be entirely inhibited upon neutrophilic differentiation and was accompanied by an increase in intracellular lipid droplet content and significant enrichment of 22 lipid gene ontology terms related to lipid metabolism in differentiated cells. These findings suggest that galectin-12 could serve as a marker of neutrophilic plasticity or polarization into different phenotypes and that galectin-12 secretion may be influenced by lipid droplet biogenesis.

Circ_005077 accelerates myocardial lipotoxicity induced by high-fat diet via CyPA/p47PHOX mediated ferroptosis

The long-term high-fat diet (HFD) can cause myocardial lipotoxicity, which is characterized pathologically by myocardial hypertrophy, fibrosis, and remodeling and clinically by cardiac dysfunction and heart failure in patients with obesity and diabetes. Circular RNAs (circRNAs), a novel class of noncoding RNA characterized by a ring formation through covalent bonds, play a critical role in various cardiovascular diseases. However, few studies have been conducted to investigate the role and mechanism of circRNA in myocardial lipotoxicity. Here, we found that circ_005077, formed by exon 2-4 of Crmp1, was significantly upregulated in the myocardium of an HFD-fed rat. Furthermore, we identified circ_005077 as a novel ferroptosis-related regulator that plays a role in palmitic acid (PA) and HFD-induced myocardial lipotoxicity in vitro and in vivo. Mechanically, circ_005077 interacted with Cyclophilin A (CyPA) and inhibited its degradation via the ubiquitination proteasome system (UBS), thus promoting the interaction between CyPA and p47phox to enhance the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase responsible for ROS generation, subsequently inducing ferroptosis. Therefore, our results provide new insights into the mechanisms of myocardial lipotoxicity, potentially leading to the identification of a novel therapeutic target for the treatment of myocardial lipotoxicity in the future.

Changed regulation of granulocyte NADPH oxidase activity in the mouse model of obesity-induced type 2 diabetes mellitus

NADPH oxidase is a target of hyperglycemia in type 2 diabetes mellitus (T2DM), which causes dysregulation of enzyme. Alterations in regulation of NADPH oxidase activity mediated receptor and non-receptor signaling in bone marrow granulocytes of mice with obesity-induced T2DM were studied. The animals fed high fat diet (516 kcal/100 g) for 16 weeks. NADPH oxidase-related generation of reactive species (RS) at normo- and hyperthermia was estimated using chemiluminescent analysis. The redox status of the cells was assessed by Redox Sensor Red CC-1. Baseline biochemical indicators in blood (glucose, cholesterol, HDL and LDL levels) were significant higher in T2DM mice versus controls. Using specific inhibitors, signaling mediated by formyl peptide receptors (FPRs) to NADPH oxidase was shown to involve PLC, PKC, cytochrome p450 in both control and T2DM groups and PLA2 in controls. In T2DM regulation of NADPH oxidase activity via mFpr1, a high-affinity receptors, occurred with a significant increase of the role of PKC isoforms and suppression of PLA2 participation. Significant differences between this regulation via mFpr2, low-affinity receptors, were not found. Non-receptor activation of NADPH oxidase with ionomycin (Ca2+ ionophore) or phorbol ester (direct activator of PKC isoforms) did not revealed differences in the kinetic parameters between groups at 37 °C and 40 °C. When these agents were used together (synergistic effect), lower sensitivity of cells to ionophore was observed in T2DM at both temperatures. Redox status in responses to opsonized zymosan was higher in T2DM mice at 37 °C and similar to control levels at 40 °C. ROC-analysis identified Tmax, RS production and effect of opsonized zymosan as the most significant predictors for discriminating between groups. It was concluded that Ca2+-dependent/PKC-mediated regulation of NADPH oxidase activity was altered in BM granulocytes from diabetic mice.

Neutrophil Extracellular DNA Traps in Response to Infection or Inflammation, and the Roles of Platelet Interactions

Neutrophils present the host's first line of defense against bacterial infections. These immune effector cells are mobilized rapidly to destroy invading pathogens by (a) reactive oxygen species (ROS)-mediated oxidative bursts and (b) via phagocytosis. In addition, their antimicrobial service is capped via a distinct cell death mechanism, by the release of their own decondensed nuclear DNA, supplemented with a variety of embedded proteins and enzymes. The extracellular DNA meshwork ensnares the pathogenic bacteria and neutralizes them. Such neutrophil extracellular DNA traps (NETs) have the potential to trigger a hemostatic response to pathogenic infections. The web-like chromatin serves as a prothrombotic scaffold for platelet adhesion and activation. What is less obvious is that platelets can also be involved during the initial release of NETs, forming heterotypic interactions with neutrophils and facilitating their responses to pathogens. Together, the platelet and neutrophil responses can effectively localize an infection until it is cleared. However, not all microbial infections are easily cleared. Certain pathogenic organisms may trigger dysregulated platelet-neutrophil interactions, with a potential to subsequently propagate thromboinflammatory processes. These may also include the release of some NETs. Therefore, in order to make rational intervention easier, further elucidation of platelet, neutrophil, and pathogen interactions is still needed.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

Differential superoxide production in phosphorylated neuronal nitric oxide synthase mu and alpha variants

Neuronal nitric oxide synthase (nNOS) is regulated by phosphorylation in vivo, yet the underlying biochemical mechanisms remain unclear, primarily due to difficulty in obtaining milligram quantities of phosphorylated nNOS protein; detailed spectroscopic and rapid kinetics investigations require purified protein samples at a concentration in the range of hundreds microM. Moreover, the functional diversity of the nNOS isoform is linked to its splice variants. Also of note is that determination of protein phosphorylation stoichiometry remains as a challenge. To address these issues, this study first expanded a recent genetic code expansion approach to produce phosphorylated rat nNOSμ and nNOSα holoproteins through site-specific incorporation of phosphoserine (pSer) at residues 1446 and 1412, respectively; this site is at the C-terminal tail region, a NOS-unique regulatory element. A quantitative mass spectrometric approach was then developed in-house to analyze unphosphorylated peptides in phosphatase-treated and -untreated phospho-nNOS proteins. The observed pSer-incorporation efficiency consistently exceeded 80%, showing high pSer-incorporation efficiency. Notably, EPR spin trapping results demonstrate that under l-arginine-depleted conditions, pSer1412 nNOSα presented a significant reduction in superoxide generation, whereas pSer1446 nNOSμ exhibited the opposite effect, compared to their unphosphorylated counterparts. This suggests that phosphorylation at the C-terminal tail has a regulatory effect on nNOS uncoupling that may differ between variant forms. Furthermore, the methodologies for incorporating pSer into large, complex protein and quantifying the percentage of phosphorylation in recombinant purified protein should be applicable to other protein systems.

Neutrophil extracellular traps and neutrophilic dermatosis: an update review

Neutrophils have both antimicrobial ability and pathogenic effect in the immune system, neutrophil extracellular traps (NETs) formation is one of the representative behaviors of their dual role. NETs formation was triggered by pathogen-related components and pathogen non-related proteins as cytokines to exert its effector functions. Recent studies indicate that the pathogenicity of NETs contributed to several skin diseases such as psoriasis, Stevens-Johnson syndrome, toxic epidermal necrolysis, and neutrophilic dermatosis. Especially in neutrophilic dermatosis, a heterogeneous group of inflammatory skin disorders characterized with sterile neutrophilic infiltrate on dermis, NETs formation was reported as the way of participation of neutrophils in the pathogenesis of these diseases. In this review, we describe the different processes of NETs formation, then summarized the most recent updates about the pathogenesis of neutrophilic dermatosis and the participation of NETs, including pyoderma gangrenosum and PAPA syndrome, Behçet syndrome, hidradenitis suppurativa, Sweet Syndrome, pustular dermatosis and other neutrophilic dermatosis. Furthermore, we discuss the link between NETs formation and the development of neutrophilic dermatosis.

IL-13 neutralization attenuates carotid artery intimal hyperplasia and increases endothelial cell migration via modulating the JAK-1/STAT-3 signaling pathway

The aim of this study was to investigate how the concentration of interleukin-13 (IL-13) affects the regulation of endothelial cell migration after injury. The incubation of recombinant human interleukin-13 (rhIL-13) strongly increased the content of reactive oxygen species (ROS) in HUVECs via the JAK-1/STAT-3/NOX-4 signaling pathway. Antagonizing the high intracellular ROS that was induced by rhIL-13 promoted the migration of HUVECs. Furthermore, IL-13 neutralization not only inhibited intimal hyperplasia, but also promoted the migration of endothelial cells (ECs) after injury. The results suggest that IL-13 inhibition is a potential means of stimulating endothelial cells recovery after injury. Therefore, the attenuation of IL-13 activation may have therapeutic value for vascular disease.

Biofilms in Periprosthetic Orthopedic Infections Seen through the Eyes of Neutrophils: How Can We Help Neutrophils?

Despite advancements in our knowledge of neutrophil responses to planktonic bacteria during acute inflammation, much remains to be elucidated on how neutrophils deal with bacterial biofilms in implant infections. Further complexity transpires from the emerging findings on the role that biomaterials play in conditioning bacterial adhesion, the variety of biofilm matrices, and the insidious measures that biofilm bacteria devise against neutrophils. Thus, grasping the entirety of neutrophil-biofilm interactions occurring in periprosthetic tissues is a difficult goal. The bactericidal weapons of neutrophils consist of the following: ready-to-use antibacterial proteins and enzymes stored in granules; NADPH oxidase-derived reactive oxygen species (ROS); and net-like structures of DNA, histones, and granule proteins, which neutrophils extrude to extracellularly trap pathogens (the so-called NETs: an allusive acronym for "neutrophil extracellular traps"). Neutrophils are bactericidal (and therefore defensive) cells endowed with a rich offensive armamentarium through which, if frustrated in their attempts to engulf and phagocytose biofilms, they can trigger the destruction of periprosthetic bone. This study speculates on how neutrophils interact with biofilms in the dramatic scenario of implant infections, also considering the implications of this interaction in view of the design of new therapeutic strategies and functionalized biomaterials, to help neutrophils in their arduous task of managing biofilms.

Independent and Interactive Roles of Immunity and Metabolism in Aortic Dissection

Aortic dissection (AD) is a cardiovascular disease that seriously endangers the lives of patients. The mortality rate of this disease is high, and the incidence is increasing annually, but the pathogenesis of AD is complicated. In recent years, an increasing number of studies have shown that immune cell infiltration in the media and adventitia of the aorta is a novel hallmark of AD. These cells contribute to changes in the immune microenvironment, which can affect their own metabolism and that of parenchymal cells in the aortic wall, which are essential factors that induce degeneration and remodeling of the vascular wall and play important roles in the formation and development of AD. Accordingly, this review focuses on the independent and interactive roles of immunity and metabolism in AD to provide further insights into the pathogenesis, novel ideas for diagnosis and new strategies for treatment or early prevention of AD.

Mitochondrial dysfunction as a possible trigger of neuroinflammation at post-traumatic stress disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a neuropsychiatric disorder that occurs in approximately 15% of people as a result of some traumatic events. The main symptoms are re-experiencing and avoidance of everything related to this event and hyperarousal. The main component of the pathophysiology of PTSD is an imbalance in the functioning of the hypothalamic-pituitary-adrenal axis (HPA) and development of neuroinflammation. In parallel with this, mitochondrial dysfunction is observed, as in many other diseases. In this review, we focus on the question how mitochondria may be involved in the development of neuroinflammation and its maintaining at PTSD. First, we describe the differences in the operation of the neuro-endocrine system during stress versus PTSD. We then show changes in the activity/expression of mitochondrial proteins in PTSD and how they can affect the levels of hormones involved in PTSD development, as well as how mitochondrial damage/pathogen-associated molecule patterns (DAMPs/PAMPs) trigger development of inflammation. In addition, we examine the possibility of treating PTSD-related inflammation using mitochondria as a target.

Role of Mitochondria in the Regulation of Effector Functions of Granulocytes

Granulocytes (neutrophils, eosinophils, and basophils) are the most abundant circulating cells in the innate immune system. Circulating granulocytes, primarily neutrophils, can cross the endothelial barrier and activate various effector mechanisms to combat invasive pathogens. Eosinophils and basophils also play an important role in allergic reactions and antiparasitic defense. Granulocytes also regulate the immune response, wound healing, and tissue repair by releasing of various cytokines and lipid mediators. The effector mechanisms of granulocytes include the production of reactive oxygen species (ROS), degranulation, phagocytosis, and the formation of DNA-containing extracellular traps. Although all granulocytes are primarily glycolytic and have only a small number of mitochondria, a growing body of evidence suggests that mitochondria are involved in all effector functions as well as in the production of cytokines and lipid mediators and in apoptosis. It has been shown that the production of mitochondrial ROS controls signaling pathways that mediate the activation of granulocytes by various stimuli. In this review, we will briefly discuss the data on the role of mitochondria in the regulation of effector and other functions of granulocytes.

Morphology of Neutrophils during Their Activation and NETosis: Atomic Force Microscopy Study

Confocal microscopy and fluorescence staining of cellular structures are commonly used to study neutrophil activation and NETosis. However, they do not reveal the specific characteristics of the neutrophil membrane surface, its nanostructure, and morphology. The aim of this study was to reveal the topography and nanosurface characteristics of neutrophils during activation and NETosis using atomic force microscopy (AFM). We showed the main stages of neutrophil activation and NETosis, which include control cell spreading, cell fragment formation, fusion of nuclear segments, membrane disruption, release of neutrophil extracellular traps (NETs), and final cell disintegration. Changes in neutrophil membrane nanosurface parameters during activation and NETosis were quantified. It was shown that with increasing activation time there was a decrease in the spectral intensity of the spatial periods. Exposure to the activator A23187 resulted in an increase in the number and average size of cell fragments over time. Exposure to the activators A23187 and PMA (phorbol 12-myristate 13-acetate) caused the same pattern of cell transformation from spherical cells with segmented nuclei to disrupted cells with NET release. A23187 induced NETosis earlier than PMA, but PMA resulted in more cells with NETosis at the end of the specified time interval (180 min). In our study, we used AFM as the main research tool. Confocal laser-scanning microscopy (CLSM) images are provided for identification and detailed analysis of the phenomena studied. In this way, we exploited the advantages of both techniques.

Neutrophil reactive oxygen formation, bacterial infections and mortality in malnourished hemodialysis patients: Evaluation of clinical outcomes

INTRODUCTION

Patients with end stage kidney disease undergoing maintenance hemodialysis (MHD) are prone to malnutrition and infections.

OBJECTIVE

The objective of this study was to evaluate the effect of polymorphonuclear (PMN) cell dysfunction on clinical outcomes of MHD patients, in association with nutritional status.

METHODS

This prospective study investigated 39 MHD patients by evaluating the oxidative activity of their PMN cells using Phorbol 12-Myristate-13-Acetate (PMA) stimulation. Blood samples were taken from each participant at dialysis initiation. Demographics, laboratory data, and clinical outcomes during a 24-month follow-up period were obtained from electronic medical records.

RESULTS

Phagocytic activity was described in percentiles of mean fluorescence intensity (MFI) of PMA levels. There were no differences in comorbidities between patients with low or high MFI-PMA percentiles. Patients in the lowest (25th) MFI-PMA percentile (N = 10) had poorer nutritional status and more frequent severe infections compared to the other 29 patients (4.3 ± 3.4 events versus 2 ± 2.2 events, p = 0.017). Furthermore, they had more frequent hospitalizations (>3) due to infections (70% versus 41%, p = 0.073) and their mortality rate was higher (80% versus 31%, p = 0.007). The odds ratio for all-cause mortality was 8.85. In multivariate analysis, the MFI-PMA percentile and ischemic heart disease were the strongest predictors of all-cause mortality (p = 0.02 and p = 0.005, respectively).

CONCLUSIONS

Low MFI-PMA levels were associated with poor nutritional status and adverse clinical outcomes and might serve as a prognostic biomarker, predicting severe infections and mortality among malnourished MHD patients.

Fast and furious: The neutrophil and its armamentarium in health and disease

Neutrophils are powerful effector cells leading the first wave of acute host-protective responses. These innate leukocytes are endowed with oxidative and nonoxidative defence mechanisms, and play well-established roles in fighting invading pathogens. With microbicidal weaponry largely devoid of specificity and an all-too-well recognized toxicity potential, collateral damage may occur in neutrophil-rich diseases. However, emerging evidence suggests that neutrophils are more versatile, heterogeneous, and sophisticated cells than initially thought. At the crossroads of innate and adaptive immunity, neutrophils demonstrate their multifaceted functions in infectious and noninfectious pathologies including cancer, autoinflammation, and autoimmune diseases. Here, we discuss the kinetics of neutrophils and their products of activation from bench to bedside during health and disease, and provide an overview of the versatile functions of neutrophils as key modulators of immune responses and physiological processes. We focus specifically on those activities and concepts that have been validated with primary human cells.

Cross-Talk of NADPH Oxidases and Inflammation in Obesity

Obesity is a major risk factor for cardiovascular and metabolic diseases. Multiple experimental and clinical studies have shown increased oxidative stress and inflammation linked to obesity. NADPH oxidases are major sources of reactive oxygen species in the cardiovascular system and in metabolically active cells and organs. An impaired balance due to the increased formation of reactive oxygen species and a reduced antioxidative capacity contributes to the pathophysiology of cardiovascular and metabolic diseases and is linked to inflammation as a major pathomechanism in cardiometabolic diseases. Non-alcoholic fatty liver disease is particularly characterized by increased oxidative stress and inflammation. In recent years, COVID-19 infections have also increased oxidative stress and inflammation in infected cells and tissues. Increasing evidence supports the idea of an increased risk for severe clinical complications of cardiometabolic diseases after COVID-19. In this review, we discuss the role of oxidative stress and inflammation in experimental models and clinical studies of obesity, cardiovascular diseases, COVID-19 infections and potential therapeutic strategies.

The metabolic function of pyruvate kinase M2 regulates reactive oxygen species production and microbial killing by neutrophils

Neutrophils rely predominantly on glycolytic metabolism for their biological functions, including reactive oxygen species (ROS) production. Although pyruvate kinase M2 (PKM2) is a glycolytic enzyme known to be involved in metabolic reprogramming and gene transcription in many immune cell types, its role in neutrophils remains poorly understood. Here, we report that PKM2 regulates ROS production and microbial killing by neutrophils. Zymosan-activated neutrophils showed increased cytoplasmic expression of PKM2. Pharmacological inhibition or genetic deficiency of PKM2 in neutrophils reduced ROS production and Staphylococcus aureus killing in vitro. In addition, this also resulted in phosphoenolpyruvate (PEP) accumulation and decreased dihydroxyacetone phosphate (DHAP) production, which is required for de novo synthesis of diacylglycerol (DAG) from glycolysis. In vivo, PKM2 deficiency in myeloid cells impaired the control of infection with Staphylococcus aureus. Our results fill the gap in the current knowledge of the importance of lower glycolysis for ROS production in neutrophils, highlighting the role of PKM2 in regulating the DHAP and DAG synthesis to promote ROS production in neutrophils.

Polymorphism in neutrophil cytosolic factor 4 (NCF4) of dairy cows had mastitis in previous lactations, and the relationship with the respiratory burst

Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase), as a key factor in innate immunity, consists of several components, one of them is p40phox which is encoded by neutrophil cytosolic factor 4 (NCF4). Respiratory burst and reactive oxygen species (ROS) production are antimicrobial mechanisms associated with NADPH oxidase. This study evaluated the effects of g.18174 A > G and g.18270C > T single-nucleotide polymorphisms (SNP) in NCF4 on bovine mastitis and the respiratory burst capacity of neutrophils. SNPs of 160 dairy cattle were determined using a novel PCR-RFLP protocol by employing restriction enzymes, MboI and FokI. Also, the flow cytometry measured respiratory burst in 82 blood samples. Our results indicated that only g.18174 A > G SNP reduced the respiratory burst capacity. However, both SNPs were not significantly correlated with clinical mastitis. We concluded that g.18174 A > G decreases the function of NADPH oxidase. However, both SNPs were not significantly correlated with clinical mastitis.

Moonlighting chromatin: when DNA escapes nuclear control

Extracellular chromatin, for example in the form of neutrophil extracellular traps (NETs), is an important element that propels the pathological progression of a plethora of diseases. DNA drives the interferon system, serves as autoantigen, and forms the extracellular scaffold for proteins of the innate immune system. An insufficient clearance of extruded chromatin after the release of DNA from the nucleus into the extracellular milieu can perform a secret task of moonlighting in immune-inflammatory and occlusive disorders. Here, we discuss (I) the cellular events involved in the extracellular release of chromatin and NET formation, (II) the devastating consequence of a dysregulated NET formation, and (III) the imbalance between NET formation and clearance. We include the role of NET formation in the occlusion of vessels and ducts, in lung disease, in autoimmune diseases, in chronic oral disorders, in cancer, in the formation of adhesions, and in traumatic spinal cord injury. To develop effective therapies, it is of utmost importance to target pathways that cause decondensation of chromatin during exaggerated NET formation and aggregation. Alternatively, therapies that support the clearance of extracellular chromatin are conceivable.